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1.0 Introduction

The purpose of Guideline A-14: Guideline for the Control of Air Emissions from Small Wood-Fired Combustors (< 3 MW) is to establish the minimum expectations necessary to control air emissions from small wood-fired combustors with a nominal load heat input capacity of less than 3 megawatts (MW) in Ontario. This guideline complements Guideline A-13: Guideline for the Control of Air Emissions from Large Wood-Fired Combustors (≥ 3 MW). Together, these two air quality guidelines serve to replace the Interim Design and Review Guidelines for Wood Fired Combustors published by the Ministry in 1990.

The intended audience for this guideline includes persons applying for an environmental compliance approval (ECA) under section 20.2 of the Environmental Protection Act, R.S.O. 1990 (the “EPA”), persons that own or operate small wood-fired combustors, and manufacturers and distributors of small wood-fired combustors.

The intended audience for this guideline does not include a person engaging in the installation, use, operation, replacement or modification a small wood-fired combustor where that activity is a prescribed activity for the purposes of section 20.21 (1) of the EPA. Persons engaging in prescribed activities that involve the use of a small wood-fired combustor are referred to O. Reg. 01/17 “Registrations under Part II.2 of the Act – Activities Requiring Assessment of Air Emissions” made under the EPA and the EASR publication, in particular chapters 1 and 5 of the EASR publication.

During the review of an application for an ECA and when considering issuing an order, the Directorfootnote 1 considers the requirements set out in relevant regulations as well as all applicable Ontario Ministry of the Environment and Climate Change (Ministry) guidelines and policies. To the extent that this document sets out that something is “required” or “shall” be done or sets out a “requirement” or “limit”, it does so only to identify minimum expectations, the application of which remain subject to the discretion of the Director. The expectations set out in this guideline are compulsory to the extent that they are contained in conditions of an ECA or other legally binding instrument, such as an order. Information pertaining to the ECA process is provided in Appendix D.

As a complement to the minimum expectations for small wood-fired combustors set out in this guideline, additional technical information is provided in Appendix E. This information could be considered before purchasing a small wood-fired combustor.

While every effort has been made to ensure the accuracy of the information contained in this guideline, it should not be construed as legal advice. In the event of a conflict with requirements of the EPA, O. Reg. 419/05 or any other regulation, the legislative requirements shall determine the appropriate approach.

2.0 Definitions and Abbreviations

The following definitions apply for the purposes of this guideline:

air pollution control equipment
means equipment that is designed to decrease emissions to the air of one or more contaminants that are present in the flue gas stream
CAN/CSA-ISO 17225-2:15
means the standard CAN/CSA-ISO 17725-2:15, published by the Canada National Standard/Canadian Standards – International Organization for Standardization on March 1, 2015 and entitled “Solid biofuels – Fuel specifications and classes - Part 2: Graded Wood pellets”
CAN/CSA-ISO 17225-3:15
means the standard CAN/CSA-ISO 17725-3:15, published by the Canada National Standard/Canadian Standards – International Organization for Standardization on March 1, 2015 and entitled “Solid biofuels – Fuel specifications and classes - Part 3: Graded Wood briquettes”
CAN/CSA-ISO 17225-4:15
means the standard CAN/CSA-ISO 17225-4:15, published by the Canada National Standard/Canadian Standards – International Organization for Standardization on March 1, 2015 and entitled “Solid Biofuels – Fuel specifications and classes – Part 4: Graded wood chips”
certified small wood-fired combustor

means a small wood-fired combustor that meets the following criteria:

  1. Subject to paragraphs 2 and 3, the combustor meets the requirements of EN 303-5 (2012).
  2. The combustor is designed to meet the Class 5 thermal efficiency and carbon monoxide requirements set out in EN 303-5 (2012) at nominal load and partial load heat output capacity operating conditions.
  3. The combustor is designed, taking into account any air pollution control equipment specified by the manufacturer, to meet at least one of Class 3, 4 or 5 for dust (particulate matter) as set out in EN 303-5 (2012) at nominal load and partial load heat output capacity operating conditions.

  4. The criteria set out in paragraphs 1 to 3 must be confirmed by a person who,

    1. does not own, operate, sell or manufacture the small wood-fired combustor, and
    2. meets the EN ISO/IEC 17025 requirements for testing as described in EN 303-5 (2012);
combustor
means a device in which combustible material is oxidized resulting in release of heat and products of combustion
commissioning period
means the 90-day period following the first start-up of a small wood-fired combustor
cyclone
means a piece of air pollution control equipment that uses centrifugal force to separate particulate matter from the flue gas
ECA
means environmental compliance approval, as defined in subsection 1(1) of the Environmental Protection Act
EN 303-5 (2012)
means European Standard EN 303-5, published by the European Committee for Standardization in June, 2012 and entitled “Heating boilers – Part 5: Heating boilers for solid fuels, manually and automatically stoked, nominal heat output of up to 500 kW – Terminology, requirements, testing and marking”
existing small wood-fired combustor

means a non-reassessed small wood-fired combustor,

  1. that was installed on or before January 31, 2017, or
  2. for which an application for an ECA was made on or before January 31, 2017;
existing ECA
means an Environmental Compliance Approval issued by the Director for a small wood-fired combustor on or before January 31, 2017
flue gas
means a gas that is generated from a combustion process
furnace
means a part of a combustor where combustion takes place and may be comprised of primary, secondary and tertiary combustion chambers
Guideline A-13
means Guideline for the Control of Air Emissions from Large Wood-Fired Combustors (≥ 3 MW) published by the Ministry in January 2015 (as amended)
higher heating value
means the amount of heat released during the complete combustion of a unit quantity of fuel and includes the latent heat of vapourization of the water vapour formed by the combustion
mg/Rm3
means milligrams per cubic metre at reference conditions
Minister
means the Minister of the Environment and Climate Change or such other member of the Executive Council as may be assigned the administration of the Environmental Protection Act, R.S.O. 1990 under the Executive Council Act
Ministry
means the ministry of the Minister
moisture content
means the total moisture content of a sample of wood fuel, as-fired, reported on a wet basis as a percentage
MW
means megawatt and is equal to 3,600 megaJoules per hour
new small wood-fired combustor
means a small wood-fired combustor, the installation of which began after January 31, 2017 and in in respect of which, no application for an ECA was made on or before January 31, 2017
nominal load heat input capacity
means the design capacity of a small wood-fired combustor to combust a maximum amount of wood fuel based on the physical design of the small wood-fired combustor and is calculated by multiplying the mass flow rate of the wood fuel by the higher heating value of the wood fuel
nominal load heat output capacity
means the maximum continuous usable heat output as determined by the nominal load heat input capacity and design of the heat exchanger
oxygen lambda sensor
means a device that continuously measures the concentration of oxygen in the flue gas on a wet basis and uses the resulting measurement as an input to the oxygen trim system
oxygen trim system
means the components of a small wood-fired combustor that dynamically control the excess oxygen level in the flue gas through the use of an oxygen lambda sensor
partial load heat input capacity
means the design capacity of a small wood-fired combustor to combust a minimum amount of wood fuel based on the physical design of the small wood-fired combustor, for which air emissions can be reliably measured at steady state conditions, and is calculated by multiplying the mass flow rate of the wood fuel by the higher heating value of the wood fuel
partial load heat output capacity
means the minimum continuous usable heat output as determined by the partial load heat input capacity and design of the heat exchanger
particulate matter
means particulate matter in the flue gas downstream of any air pollution control equipment, prior to discharge to the air, that has an aerodynamic diameter of less than 44 microns
reassessed small wood-fired combustor
means an existing small wood-fired combustor at a facility for which an application for an ECA in respect to an activity engaged in at the facility has been made after January 31, 2017
record
includes a written procedure, a measurement result, a written notification, a table, a report, a document, electronic data, a written practice, and an update to any of the preceding
reference conditions
mean conditions at which the temperature is 25 degrees Celsius and the pressure is 101.3 kilopascals
small wood-fired combustor

means a wood-fired combustor that has,

  1. a nominal load heat input capacity of less than three megawatts, and
  2. a nominal load heat output capacity of greater than 50 kilowatts;
thermal efficiency
means the ratio of the delivered useful heat output to the heat input as derived from the wood fuel, expressed as a percentage
uncertified small wood-fired combustor
means a small wood-fired combustor that does not meet the requirements set out in the definition of a “certified small wood-fired combustor”
ungraded wood material
means woody biomass that has not been processed into a wood briquette, wood pellet or wood chip
wood briquette
means a densified wood fuel with a diameter of more than 25 millimetres produced by compressing woody biomass as defined by CAN/CSA-ISO 17225-3:15
wood chip
means a piece of wood within a defined size range, cut or chipped from a larger piece of wood as defined by CAN/CSA-ISO 17225-4:15
wood-fired combustor
means a combustion source designed to burn wood fuel and does not include a wood-fuel gasifier connected to an internal combustion engine
wood pellet
means a densified wood fuel made by compressing woody biomass into a cylindrical form as defined by CAN/CSA-ISO 17225-2:15

3.0 Applicability

This guideline applies to small wood-fired combustors that are designed to burn wood fuel set out in this guideline (i.e., wood pellets, wood briquettes or wood chipsfootnote 2) rated to a nominal load heat input capacity of less than 3 MW and a nominal load heat output capacity of greater than 50 kW. This guideline does not apply to a combustor that burns ungraded wood fuel or fuel other than wood fuel (e.g. agricultural sourced biomass). Please refer to Guideline A-13 (Guideline for the Control of Air Emissions from Large Wood-Fired Combustors ≥ 3 MW) for the Ministry’s expectations regarding wood-fired combustors that use ungraded wood material or up to 7.5% municipal waste (that is predominantly wood) material as a fuel.

Certain expectations set out in this guideline vary according to whether the small wood-fired combustor is: (i) a new small wood-fired combustor; (ii) a reassessed small wood-fired combustor; or (iii) an existing small wood- fired combustor. Unless exempt from section 9 of the EPA, it is an offence under the EPA to operate a small wood-fired combustor without an ECA and an application for an ECA should be made forthwith. It should be noted that the following are the ministry’s expectations with respect to such an ECA application:

  1. If the operation of the small wood-fired combustor commenced before January 31, 2017, it is expected that the person will follow the expectations set out for a reassessed small wood-fired combustor.
  2. If the operation of the small wood-fired combustor commenced after January 31, 2017, it is expected that the person will follow the expectations set out for a new small wood-fired combustor.

This guideline also distinguishes between small wood-fired combustors that are certified (i.e. have been independently tested and have documentation to demonstrate compliance with European Standard EN 303-5 (2012), including Class 5 for thermal efficiency and carbon monoxide emissions and either Class 3, 4 or 5 for dust) and those that are uncertified. A certified small wood-fired combustor will be considered uncertified if it is modified to be equipped with a direct contact heat exchanger (e.g., direct contact grain dryer).

The expectations set out in this guideline for certified small wood-fired combustors also apply to a small wood-fired combustor that meets the following criteria:

  • If a small wood-fired combustor has a nominal load heat output capacity of more than 500 kW, it meets all four of the criteria of the definition of “certified small wood-fired combustor” other than having a nominal load heat output capacity of less than or equal to 500 kW (note that EN 303-5 (2012) is limited to nominal load heat output capacity of up to 500 kW), and
  • If the small wood-fired combustor has a non-contact air-to-air heat exchanger, the small wood-fired combustor meets the criteria set out in paragraph 1 of the definition of “certified small wood-fired combustor” and meets the criteria set out in paragraph 2 with respect to carbon monoxide and meets the criteria set out in paragraphs 3 and 4 of that definition.

4.0 Wood Fuel Parameters

A small wood-fired combustor is expected to use the wood fuel that the manufacturer designed it to use, subject to the specifications outlined below.

4.1 Wood Fuel Specifications

New and Reassessed Small Wood-Fired Combustors

A new or reassessed small wood-fired combustor is expected to use wood fuel that meets one or more of the following specifications:

Wood pellets:

  1. CAN/CSA-ISO 17225-2:15: Type A1, A2 or B graded wood pellets for commercial and residential applications (ISO 17225-2 has superseded EN 14961-2);
  2. Pellet Fuels Institute: premium or standard grade as set out in the document entitled “Pellet Fuels Institute Standard Specifications for Residential/Commercial Densified Fuel”, published by the Pellet Fuels Institute in July 2015.

Wood chips:

  1. moisture content is 50% or less, and
  2. CAN/CSA-ISO 17225-4:15: Type A1, A2, B1 or B2 graded wood chips (ISO 17225-4 has superseded EN 14961-4).

Wood briquettes:

  1. CAN/CSA-ISO 17225-3:15: Type A1, A2 or B

For wood chips, the expectation of the 50% or less moisture content will begin on January 31, 2017, but the specification set out in clause ii will be considered voluntary until January 31, 2027 after which compliance with the specification will be expected. Refer to Appendix F for more detailed descriptions of the above-noted wood fuel specifications.

Please note that a person responsible for a small wood-fired combustor that seeks to use a form of wood fuel other than wood briquettes, wood pellets or wood chips, when applying for an ECA on or after January 31, 2017, is expected to meet the requirements of Guideline A-13.

Existing Small Wood-Fired Combustors

For an existing small wood-fired combustor, it is considered good practice to use a wood fuel quality specification that optimizes combustion efficiency and minimizes air emissions. Using the wood fuel types described above is a recommended best practice.

4.2 Automated Wood Fuel Feed Systems for New and Reassessed Small Wood-Fired Combustors

An automated wood fuel feed system inserts wood fuel into a combustor furnace under the control of a computational algorithm that operates in conjunction with the oxygen trim system. Such a system is anticipated to assist in ensuring consistently effective combustion, as compared with manually fed systems.

Automated wood fuel feed systems have start-up and shut down procedures that control the timing sequence and amount of combustion air and wood fuel fed into the combustor. Having these procedures incorporated into the system assists in minimizing air emissions by limiting the time for start-up and shut down as compared with manually operated systems.

Accordingly, new and reassessed small wood-fired combustors are expected to have an automated wood feed system that includes automated start-up and shutdown procedures.

4.3 Wood Fuel Management

Wood fuel quality is a critical parameter for ensuring efficient combustion and thereby minimizing air emissions. In order to ensure that each type of wood fuel being supplied to a small wood-fired combustor is of satisfactory quality and is managed in a manner that maintains the quality and characteristics of the fuel, it is expected that the person responsible for a small wood-fired combustor prepare, implement and maintain a Wood Fuel Management Plan.

New and Reassessed Small Wood-Fired Combustors

A Wood Fuel Management Plan for a new or reassessed small wood-fired combustor is expected to have the following elements:

  1. A list of the type of each wood fuel that may be stored at the facility with the intent to be burned in the small wood-fired combustor (e.g., wood briquettes, wood chips, wood pellets) and which specification in Chapter 4.1 best describes the wood fuel.
  2. A procedure to document the quantity of wood fuel purchased by the facility and the source from which it was purchased, and, if applicable, the quantity of wood fuel generated at the facility.
  3. A procedure to document how each wood fuel, wood fuel storage area and wood fuel handling and conveyance system at the facility is inspected on a regular basis.
  4. A procedure to ensure that wood fuel that is not considered acceptable for combustion at the facility is removed from the facility immediately or stored separately from the wood fuel storage until it can be removed from the facility in a timely manner. The quantity of wood fuel rejected and the reasons for the rejection should be documented.
  5. A procedure to document what steps have been taken to ascertain wood fuel quality. Such steps may include laboratory testing, documentation of third party certification provided to the wood fuel supplier, and on-site testing.
  6. An indication of the maximum time that each wood fuel may be stored at the facility. This maximum storage duration is intended to prevent degradation of the wood fuel before it is used as a fuel.

  7. If a facility uses wood chips, a procedure to,

    1. document the wood chip pile turn-over to ensure that the wood chips that have been at the facility for the longest are used first, and
    2. ensure that the wood chips fed into the small wood-fired combustor are delivered from either a heated indoor wood chip storage facility sufficient to store a minimum of 1.5 days of wood chip fuel supply at nominal load heat input capacity or unheated indoor storage facility sufficient to store a minimum of three days of wood chip fuel supply at nominal load heat input capacity. The wood chips may be delivered either directly from the indoor storage facility to the combustor if both are housed in one structure, or indirectly from the storage facility into the combustor fuel hopper through a conveyance system if housed in separate structures.
  8. If a facility uses wood pellets or wood briquettes, a procedure to ensure that the wood pellets and wood briquettes are covered by a weather proof enclosure.

Existing Small Wood-Fired Combustors

The Ministry considers it a best practice for a Wood Fuel Management Plan pertaining to an existing small wood-fired combustor to have the elements described above.

5.0 Combustor Design and Performance

This guideline distinguishes between small wood-fired combustors that are certified or uncertified. Note that the expectations set out in this guideline for certified small wood-fired combustors apply to a wood combustor that is described in Chapter 3.0 “Applicability”. Emission conversion and calculations are provided in Appendix C.

5.1 Design of New Small Wood-Fired Combustors

A new small wood-fired combustor is expected to have the following design elements:

  1. The small wood-fired combustor is to have a multi-zone air control combustion process that includes the following elements (optional elements are noted as “good practice”):

    1. The multi-zone air control combustion process is to have a primary combustion zone with a fuel bed and is to introduce primary combustion air. The primary combustion zone is to be designed to facilitate the drying and gasification of the wood fuel. It is also to be designed to ensure that solid fixed carbon is combusted with minimal carry-over of particulate matter.
    2. The multi-zone air control combustion process is to have a secondary combustion zone and is to introduce secondary combustion air. The secondary combustion zone is to be designed to achieve complete combustion of the volatized gases and any combustible particles that may be carried over from the primary combustion zone.
    3. The multi-zone air control combustion process is to have an automated bottom ash removal system.
    4. It is considered good practice for the multi-zone air control combustion process to have an automated fly ash removal system in the heat exchanger.
    5. It is considered good practice for the multi-zone air control combustion process to have a tertiary combustion zone to introduce tertiary combustion air to complete the combustion of volatilized gases.
    6. It is considered good practice for the multi-zone air control combustion process to have a flue gas recirculation system that directs a portion of the flue gases from the outlet of the induced draft fan back into the combustion air injection points.
  2. The small wood-fired combustor is to have an oxygen trim system including an oxygen lambda sensor to regulate the supply of combustion air to the primary, secondary, and, where applicable, tertiary combustion zones.
  3. The small wood-fired combustor is to use a variable speed electric fan as the induced draft fan to maintain a minimum negative static pressure in the combustion zones.
  4. The small wood-fired combustor is to have a monitor that measures the static pressure in the furnace or an alarm that signals when the static pressure in the furnace is positive.
  5. The small wood-fired combustor is to be designed to operate in a manner that results in the concentration of particulate matter in the flue gas of the discharge stack of a small wood-fired combustor, downstream of any air pollution control equipment being less than 75 mg/Rm3 at 11% oxygen (dry basis). The person responsible for the small wood-fired combustor is expected to obtain documentation from the manufacturer confirming that the small wood-fired combustor (and its air pollution control equipment as described below) is capable of achieving this emission level.

  6. The small wood-fired combustor is expected to have the following air pollution control equipment:

    • If the combustor is a certifiedfootnote 3 small wood-fired combustor:

      • Where a certified small wood-fired combustor is certified to EN 303-5 (2012) Class 3 for dust,

        • if air pollution control equipment is not required to meet Class 3 dust emission level in EN 303-5 (2012), add air pollution control equipment capable of reducing the emissions of suspended particulate matter to the air by at least 50% when the small wood-fired combustor is operating at nominal load heat input capacity.
        • if air pollution control equipment is required to meet Class 3 dust emission level in EN 303-5 (2012), add an additional piece of air pollution control equipment capable of reducing the emissions of suspended particulate matter to the air by at least 50% when the small wood- fired combustor is operating at nominal load heat input capacity.
      • Where a certified small wood-fired combustor is certified to EN 303-5 (2012) Class 4 or 5 for dust, air pollution control equipment specified by the manufacturer, if necessary, to meet the Class 4 or 5 certification emission level for dust.
    • If the combustor is an uncertified small wood-fired combustor, air pollution control equipment capable of reducing the emissions of suspended particulate matter to the air by at least 50% when the small wood-fired combustor is operating at nominal load heat input capacity.
  7. The small wood-fired combustor is to be designed so that it is capable of measuring the process control parameters set out in Chapter 7.1.

5.2 Operation of New Small Wood-Fired Combustors

A new small wood-fired combustor is expected to operate at a load that is within an operating range specified by the manufacturer (i.e., at a load that is above the partial load and below the nominal load). Similarly a new small wood-fired combustor is expected to operate at wood fuel feed rates specified by the manufacturer and operate within the range of thermal efficiencies specified by the manufacturer. These three parameters are to be documented by the person responsible for the small wood-fired combustor, based on information received from the manufacturer.

For a certifiedfootnote 4 new small wood-fired combustor the partial load heat output capacity is typically 30% of the nominal load heat output capacity, as described in EN 303-5 (2012), and third party certification emission testing for partial load is typically conducted at 30% of the nominal load heat output capacity.

However, for an uncertified new small wood-fired combustor, the person responsible for the small wood-fired combustor must document, based on information received from the manufacturer, the partial load heat input and output capacity as a percentage of the corresponding nominal load heat input and output capacity. The person responsible for the small wood-fired combustor is expected to have a written record of the partial load heat input and output capacity specifications.

It is important to note that a new small wood-fired combustor is not to operate “in idle mode” below the partial load heat input and output capacity - it is expected to operate at or above the partial load heat input and output capacity or otherwise be shut down.

As well, a new small wood-fired combustor is expected to operate in manner that ensures that the static pressure in the furnace is negative. Ensuring the furnace is drafting air and, therefore, is negatively pressurized will prevent the migration of flue gases into the structure housing the small wood-fired combustor.

It is expected that any air pollution control equipment required to be installed as a component of the small wood-fired combustor as described in Chapter 5.1 will operate at all times while the small wood-fired combustor is operational.

5.3 Flue Gas Concentration Limitsfootnote 5

New Small Wood-Fired Combustors

The concentration of carbon monoxide in the flue gas of a new small wood-fired combustor is expected to be less than 400 parts per million by volume (ppmv) at 11% oxygen on a dry basis and reference conditions averaged over a 24-hour calendar day. When calculating the daily average carbon monoxide concentration, a person may omit up to 120 non-consecutive minutes of carbon monoxide measurements while the small wood-fired combustor is operational. As well, a person may omit any carbon monoxide measurements taken after the induced draft fan shuts off following the shutdown of a small wood-fired combustor. Records of the measurements (including those that were omitted) are to be kept at the facility for a minimum of 12 months from the date the measurement was taken (see also Chapter 7).

The concentration of oxygen in the flue gas of a new small wood-fired combustor is expected to be at least 6% by volume on a dry basis at reference conditions block-averaged over a one-hour period. Note however, that the concentration of oxygen in the flue gas of a certifiedfootnote 6 new small wood-fired combustor is expected to be at least 5.5% by volume on a wet basis averaged over a one-hour period as measured by the oxygen lambda sensor. Note that a dry oxygen measurement is not required because a continuous carbon monoxide monitor is not required for certified new small wood-fired combustors (See Chapter 7.2).

Reassessed and Existing Small Wood-Fired Combustors

It is expected that a person responsible for a reassessed or existing small wood-fired combustor will meet the flue gas carbon monoxide and oxygen limits set out in their ECA. Note that the ministry will have regard to the limits for carbon monoxide and oxygen set out above in issuing or amending ECAs after January 31, 2017. It is also expected that a person responsible for a reassessed or existing small wood-fired combustor will operate in a manner that results in the concentration of particulate matter in the flue gas of the discharge stack of a small wood-fired combustor, downstream of any air pollution control equipment meeting the limit set out in their ECA. Similarly, the ministry will have regard to a concentration limit of less than 90 mg/Rm3 at 11% oxygen (dry basis) for particulate matter with respect ECAs issued or amended after January 31, 2017.

6.0 Installation and Source Testing

6.1 Installation Test for New Small Wood-Fired Combustors

During the 90-day period following the first start-up of a new small wood-fired combustor it is expected that an installation test be performed to ensure the small wood-fired combustor was installed and is operating according to the manufacturer’s design. As part of the installation test, the person responsible for the small wood-fired combustor is to ensure that a technician trained by the manufacturer inspects how the small wood-fired combustor was installed and observes the operation of the small wood-fired combustor to determine if any problems occur. The person responsible for the small wood-fired combustor is to ensure that the technician corrects any problems and is to document the work done by the technician upon successful completion of the installation test.

When performing the installation test, it is expected that the person responsible for the small wood-fired combustor ensures that the technician determines if the performance monitoring equipment (as described in Chapter 7) is functioning properly. The monitoring equipment is to be assessed for a minimum of three continuous hours at each of the following operating conditions: (i) at nominal load heat input and output capacity and (ii) at partial load heat input and output capacity. The data generated by the process monitoring devices described in Chapter 7.1 are expected to be recorded as part of the installation test. This test is intended to ensure the satisfactory performance of the performance monitoring equipment and to demonstrate that the equipment is ready to operate at steady state conditions for subsequent source testing as described in Chapter 6.2 below.

The installation test is to be performed for each type of wood fuel that is intended to be used in the small wood-fired combustor (i.e., wood pellets, wood chips and/or wood briquettes). For a small wood-fired combustor that may use wood pellets or wood briquettes, the installation test is to be performed using wood pellets or wood briquettes with the highest ash content that may be used in the small wood-fired combustor. For a small wood-fired combustor that may use wood chips, the installation test is to be performed using wood chips with the highest moisture content and ash content that may be used in the small wood-fired combustor.

As part of the installation test, the person responsible for the small wood-fired combustor must ensure that the technician uses a calibrated portable combustion gas analyzer to measure and record carbon monoxide and oxygen emission levels in the flue gas for each three-hour period concurrent with the assessment of the performance monitoring equipment at nominal load and partial load heat input and output capacity. As such, it is recommended that all new small wood-fired combustors have readily accessible emission testing ports to allow for the use of a calibrated portable combustion gas analyzer.

It is expected that the concentration of carbon monoxide measured during the installation testing be: (i) less than 100 ppmv at 11% oxygen for nominal load heat input and output capacity, and (ii) less than 200 ppmv at 11% oxygen for partial load heat input and output capacity. It is expected that the concentration of oxygen in the flue gas measured during installation testing be at least 5.5% by volume.

The person responsible for the small wood-fired combustor is to ensure that the technician compares the measurement results to the limits set out above and any other applicable limits (e.g. in an ECA). The person responsible for the small wood-fired combustor is to ensure that the technician makes any necessary adjustments or repairs to ensure that the measurement results are compliant with the limits set out above. If the small wood-fired combustor has a continuous carbon monoxide or oxygen monitor, the person responsible for the small wood-fired combustor must ensure that the technician compares the measurement results of the portable combustion gas analyzer to the measurements of the continuous monitor.

The person responsible for the small wood-fired combustor is to ensure that the technician reviews and correlates the results of the measurements described above from the process monitoring devices and combustion gas analyzer, subject to any adjustments or repairs, to determine if the small wood-fired combustor is performing well in accordance with the manufacturer’s recommendations.

It is expected that the person responsible for the small wood-fired combustor will document the results of an installation test and that a report be prepared and retained at the facility for a period of five years after the date on which the small wood-fired combustor ceases to be used at the facility. The report shall include the calibration records of the portable combustion gas analyzer.

6.2 Source Testing for Small Wood-Fired Combustors

In this guideline, a source test generally means the measurement of carbon monoxide, oxygen and particulate matter in the flue gas of the discharge stack of a small wood-fired combustor, downstream of any air pollution control equipment.

A source test is to be performed for each type of wood fuel that is intended to be used in the small wood-fired combustor at the facility (i.e., wood pellets, wood chips and/or wood briquettes). For a small wood-fired combustor that may use wood pellets or wood briquettes, the source test is to be performed using wood pellets or wood briquettes with the highest ash content that may be used in the small wood-fired combustor. For a small wood-fired combustor that may use wood chips, the source test is to be performed using wood chips with the highest moisture content and ash content that may be used in the small wood-fired combustor.

The source test report is to include a summary of the process control monitoring data described in Chapter 7 that was measured during the source test.

New Small Wood-Fired Combustors

A source test is expected to be performed no later than six months after the completion of an installation test with respect to a new small wood-fired combustor.

The source test is to measure particulate matter, carbon monoxide and oxygen in the flue gas of the new small wood-fired combustor. These parameters are to be measured at both nominal load heat input and output capacity and partial load heat input and output capacityfootnote 7; however, a certified new small wood-fired combustor need only measure carbon monoxide and oxygen at nominal load heat input and output capacity and partial load heat input and output capacity.

It is expected that the concentration of particulate matter, as measured in the flue gas after the air pollution control equipment during source testing, be less than 75 mg/Rm3 at 11% oxygen (dry basis) averaged over a period determined in accordance with the Ontario Source Testing Code.

It is expected that the concentration of carbon monoxide measured during source testing be: (i) less than 100 ppmv at 11% oxygen on a dry basis and reference conditions averaged over a one-hour period for nominal load heat input and output capacity, and (ii) less than 200 ppmv at 11% oxygen on a dry basis and reference conditions averaged over a one-hour period for partial load heat input and output capacity.

It is expected that the concentration of oxygen in the flue gas measured during source testing be at least 6% by volume on a dry basis and reference conditions averaged over a one-hour period. Note that measuring the concentration of oxygen on a dry basis enables the oxygen correction of the carbon monoxide measurements. The dry oxygen level determined during source testing must be measured separately from the wet oxygen level determined by the oxygen lambda sensor.

If a new small wood-fired combustor undergoes a significant modification, it is expected that the person responsible for the small wood-fired combustor would seek an amendment to the ECA, after which another source test will be completed according to the requirements set out in the ECA.

Reassessed and Existing Small Wood-Fired Combustors

Source testing at nominal load heat input and output capacity operating conditions is expected to be performed, in accordance with the terms and conditions of an ECA. Note that for ECAs issued or amended after January 31, 2017, the ministry will have regard to the following expectations:

  1. if it has been five years (or more) since the last source test was conducted for the small wood-fired combustor at the time when it is reassessed, source testing may be required no later than six months after the issuance of an ECA pertaining to the reassessed combustor, or
  2. if the small wood-fired combustor has been modified in such a way that it no longer conforms to the existing ECA conditions and requires an amendment to the ECA (e.g., change induced draft fan size, flow or pressure ratings, change wood fuel type and associated feed system), source testing may be required no later than six months after the commissioning period of the modified combustor, or
  3. with respect to an application for an ECA with respect to an existing small wood-fired combustor that has been operating without an ECA, where one is required, source testing is expected to be performed no later than six months after the issuance of an ECA pertaining to the existing small wood- fired combustor.

It is expected that the concentration of particulate matter in the flue gas measured downstream of any air pollution control equipment during source testing be less than 90 mg/Rm3 at 11% oxygen (dry basis) averaged over a period determined in accordance with the Ontario Source Testing Code.

It is expected that the concentration of carbon monoxide measured during source testing be less than 100 ppmv at 11% oxygen on a dry basis and reference conditions averaged over a one-hour period.

It is expected that the concentration of oxygen in the flue gas measured during source testing be at least 6% by volume on a dry basis and reference conditions averaged over a one-hour period.

A summary of the source testing expectations are provided in Appendix A.

7.0 Performance Monitoring

7.1 Process Control Monitoring for Small Wood-Fired Combustors

New Small Wood-Fired Combustors

The Ministry expects that certain process control parameters will be monitored and recorded while a new small wood-fired combustor is operating. For the purposes of data recording, the process control monitors should measure and record for a minimum of two hours after a shutdown procedure has commenced.

The Ministry expects the following parameters to be measured continuously and that the measurements be block-averaged over every five minute period:

  1. The concentration of oxygen in the flue gas as measured by the oxygen lambda sensor (% by volume on a wet basis)
  2. An induced draft fan parameter (e.g., fan speed or % of maximum)
  3. A fuel input or energy output parameter (e.g., % of nominal load to ensure that the small wood-fired combustor does not operate below the partial load heat input capacity – see Chapter 5.2)
  4. The flue gas temperature.

The Ministry expects that each measurement be recorded and retained at the facility for at least 12 months from the date the measurement was taken.

Reassessed and Existing Small Wood-Fired Combustors

The Ministry considers it a best practice for a reassessed or existing small wood-fired combustor to have process control monitoring as described above.

7.2 Flue Gas Monitoring for Small Wood-Fired Combustors

New Small Wood-Fired Combustors

A new small wood-fired combustor is to be equipped with a monitor that continuously measures and records the concentration of carbon monoxide and oxygen in the flue gas. Note that such monitoring is not expected if the new small wood-fired combustor is certified.

In particular, it is expected that the following parameters be measured continuously and that the measurements be block-averaged over every five minute period:

  1. The undiluted concentration of carbon monoxide, reported on a dry basis and corrected to 11 % oxygen and reference conditions, in the flue gas.
  2. The undiluted percentage of oxygen by volume, reported on a dry basis and reference conditions, in the flue gas.

For new uncertified small wood-fired combustors, it is recommended that the measurements of oxygen and carbon monoxide are conducted at the same location and that the carbon monoxide monitor be configured as a dual range application with automatic range change capabilities to accurately measure emissions during both start-up and shut down operations as well as normal operations.

The process control monitoring data is intended to assist in interpreting this flue gas emission monitoring data. As such, it is expected that the times and dates for each monitor and data recording system (for both flue gas and process control monitors) be synchronized to within one minute of each other.

The Ministry expects that each carbon monoxide and oxygen measurement be recorded and retained at the facility for at least 12 months from the date the measurement was taken.

Prior to installing a new uncertified small wood-fired combustor, it is strongly recommended that a person submit a plan for the installation, operation and maintenance of the above-noted continuous flue gas monitoring devices to the Manager of Technology Standards Section, Standards Development Branch at the Ministry.

Reassessed and Existing Small Wood-Fired Combustors

The Ministry expects that a person responsible for a reassessed or existing small wood-fired combustor will comply with the terms and conditions of their ECA with regards to flue gas monitoring. Note that for ECAs issued or amended after January 31, 2017, the ministry will have regard to the expectation that a small wood-fired combustor be equipped with a monitor that continuously measures and records the concentration of carbon monoxide, oxygen and temperature in the flue gas. The Ministry also expects that each carbon monoxide, oxygen and temperature measurement be recorded and retained at the facility for at least 12 months from the date the measurement was taken.

7.3 Routine Inspections or Remote Connection

New and Reassessed Small Wood-Fired Combustors

To minimize the potential for operational malfunction of a small wood-fired combustor and associated air emissions, it is expected that new and reassessed small wood-fired combustors be (i) inspected regularly or (ii) equipped with a remote connection.

If the small wood-fired combustor is to be inspected regularly, it is expected that the routine physical inspections be performed at least once per week in accordance with recommendations of the manufacturer by a person who has received training for the purposes of conducting such inspections. The Ministry expects the results of each inspection to be recorded and maintenance activities to be performed as needed.

If a small wood-fired combustor is to be equipped with a remote connection, it is expected that the small wood-fired combustor be equipped with a 24-hour per day remote connection to either a designated facility staff member or service contractor. The remote connection should communicate error or fault alarms, messages and notifications from the facility in the event of a malfunction to enable a response in a timely manner to trouble-shoot and correct the malfunction by either attending to the combustor in person or engaging in two-way communication remotely with the combustor. The Ministry expects the results of each remote communication to be recorded and maintenance activities to be performed as needed.

Existing Small Wood-Fired Combustors

The Ministry considers it a best practice to adopt a routine inspection program or remote connection as described above for existing small wood-fired combustors.

8.0 Performance Assessment

New and Reassessed Small Wood-Fired Combustors

The Ministry expects that the person responsible for the small wood-fired combustor will ensure that a technician who is competent in heating, ventilation, and air conditioning (HVAC) technologies conducts a performance assessment at least once per year with respect to a new or reassessed small wood-fired combustor. The performance assessment is expected to include the following actions:

  1. Inspection of the following items while the small wood-fired combustor is not operating,

    1. fuel conveyance and handling equipment (e.g., is the wood fuel conveyance equipment visibly damaged?),
    2. indoor wood fuel storage area (e.g., is the indoor wood fuel storage area dry or is there evidence of water leaking in from the outdoors?),
    3. heat exchanger, air pollution control equipment, combustion air and flue gas ductwork (e.g., are the heat exchanger tubes free of corrosion and fly ash deposits, and is the ductwork free from leakage due to rust or holes?),
    4. fans and dampers (e.g., are any of the fans or dampers visibly damaged?),
    5. continuous monitoring devices (e.g., is the oxygen lambda sensor installed correctly or has it been removed?),
    6. combustion chamber air injection nozzles, grates and refractory (e.g., is there surplus bottom ash on the grate that has not been removed in a timely manner?), and
    7. bottom ash and fly ash (e.g., does the bottom ash contain a significant amount of blackened fuel particles that still have a recognizable shape because they did not burn completely?).
  2. While the small wood-fired combustor is operating at or between nominal and partial heat load, measure the carbon monoxide and oxygen emission levels in the flue gas of the small wood-fired combustor over at least a 30-minute period using a calibrated portable combustion gas analyser and record the levels of those parameters.

  3. Complete any necessary adjustments or repairs to ensure that the measurements obtained in accordance with paragraph 2 indicate the following concentrations:

    1. the concentration of carbon monoxide averaged over the test period described in paragraph 2 is less than 100 parts per million by volume (ppmv) corrected to 11 % oxygen, and
    2. the concentration of oxygen averaged over the test period described in paragraph 2 is at least 5.5% by volume.

  4. Determine if the small wood-fired combustor is performing well by reviewing:

    1. the results of the measurements required by paragraph 2, subject to any necessary adjustments or repairs, and correlating those results with the results of the measurements obtained in accordance with Chapter 7.1 over the same period;
    2. the maintenance, inspection and calibration records for each piece of continuous monitoring equipment mentioned in Chapter 7.1.

If the determination described by paragraph 4 above indicates that the small wood-fired combustor is not performing well, the person responsible for the small wood-fired combustor must ensure that necessary adjustments or repairs are made in a manner that will ensure the small wood-fired combustor is operating in accordance with the manufacturer’s recommendations and the requirements of any conditions of an ECA or other legally binding instrument.

For greater certainty, the actions described above do not replace any inspection or preventative maintenance program recommended by the manufacturer and such recommendations are expected to be implemented in addition to the actions described above. Also, the actions expected to be performed while the small wood-fired combustor is operating can be performed on a different day than the actions expected to be performed while the small wood-fired combustor is not operating, within the same year.

The person responsible for the small wood-fired combustor is expected to ensure that a record of the results of each performance assessment is created and retained for a five-year period after the record is completed. A record created is expected to include the date on which the performance assessment is performed, the observed conditions of the items to be inspected while the small wood-fired combustor is not operating, the measurements made while the small wood-fired combustor is operating, a summary of the determination made as to whether the small wood-fired combustor is performing well and a description of any adjustments or repairs made to correct the small wood-fired combustor so that it does perform well.

Existing Small Wood-Fired Combustors

The Ministry considers it a best practice to perform performance assessments for existing small wood-fired combustors as described above.

9.0 Documentation

This chapter sets out the information that is expected to be submitted in an ECA application and, with respect to a new small wood-fired combustor, documented prior to the installation of a new small wood-fired combustor. The following information on wood fuel parameters, combustor design and performance will assist the Director in assessing whether the small wood-fired combustor meets the expectations set out in this guideline (where applicable):

  1. A tabulated summary of the types and specifications of wood fuels that are proposed to be stored and intended to be used at the facility (see expectations set out in Chapter 4.1).
  2. A tabulated summary of the design, operating and performance monitoring aspects of the small wood-fired combustor and air pollution control equipment (see expectations set out in Chapters 5 and 7).
  3. A side-sectional schematic of the combustor including an illustration of the automated method of introduction of wood fuel into the furnace that meets the expectations set out in Chapter 4.2; the combustion zones (e.g., primary, secondary) and identification of points of introduction of combustion air and, where applicable, flue gas recirculation air (see expectations set out in Chapter 5).

  4. A copy of the original equipment manufacturers combustor design and operating documentationfootnote 8 that includes the following information (where available):

    1. The make and model number and nominal load heat input and output capacity and other related design features such as the air pollution control equipment (e.g., cyclone).
    2. The partial load heat input and output capacity as a % of the nominal load heat input and output capacity.
    3. The types of wood fuels capable of being used in the unit, including wood briquettes, pellets and/or chips with a provision for wood chip units that the maximum fuel moisture content is 50%.
    4. A description of the automated start-up and shutdown procedures.
    5. A description of the combustion process control parameters outlined in Chapter 7.1, including the data acquisition system capabilities.
    6. Specifications for the oxygen lambda sensor.
    7. The design operating range for excess oxygen in the flue gas and how the oxygen trim system maintains the excess oxygen at the desired level.
    8. Recommendations for operator training, routine visual inspections, remote connections and monitoring, preventative maintenance plans, spare parts, trouble-shooting, operational adjustment either on-site or remotely and periodic combustor cleaning, maintenance and tune ups.

  5. A tabulated summary of the expected air emission performance of the small wood-fired combustor for both nominal load and partial load heat input and output operating conditions (see expectations set out in Chapters 5.2 and 5.3), that includes the following information:

    1. Range of anticipated 1-hour block average oxygen concentrations (% by volume, dry and wet basis) in the flue gas and typical set-point for each wood fuel proposed for use at the facility.
    2. Maximum anticipated 24-hour daily average carbon monoxide concentration (ppmv, dry basis at 11% oxygen and reference conditions) in the flue gas.
    3. Maximum anticipated flue gas concentration of particulate matter (mg/Rm3 at 11% oxygen, dry basis) measured at a point after any air pollution control equipment.

  6. Air emission documentation that validates the above-noted maximum anticipated outlet concentrations of carbon monoxide and particulate matter for the small wood-fired combustor and air pollution control equipment that is to be included in the application for ECA. In particular:

    1. For a certifiedfootnote 9 small wood-fired combustor at least one of the following is considered acceptable if it identifies the emissions of dust (particulate matter) and demonstrates compliance with the requirements of EN 303-5 (2012) Class 5 for thermal efficiency and carbon monoxide as well as Class 3, 4 or 5 for dust at both nominal load and partial load heat input and output capacity operating conditions:

      1. the manufacturer’s guaranteed emission limits,
      2. a copy of an independent testing agency’s report.
    2. For an uncertified small wood-fired combustor, an air emission test report from an operating small wood-fired combustor in another jurisdiction that has been accepted by an environmental regulatory agency (e.g., an American State or Canadian Provincial regulator) is preferred over published emission factors. Emission data at nominal load heat input and output capacity is expected and emission data at partial load heat input and output capacity is also desired where available.
  7. Documentation summarizing the proposed continuous flue gas monitoring devices, installation location, operation and maintenance for uncertified small wood-fired combustors (see expectations set out in Chapter 7.3).

Refer to Table A-1 in Appendix A for a summary of the expectations for new and reassessed small wood-fired combustors. Table A-1 includes related notes to distinguish expectations based on certification status. Refer also to Table B-1 in Appendix B for an example of a format that would assist in providing the above-listed information.

Appendix A: Tabulated Summary of Guideline A-14 Expectations

A person responsible for a small wood-fired combustor that has an ECA must meet the requirements set out in the ECA. For existing small wood-fired combustors that have an ECA the items listed in Table A-1 under the column entitled “Reassessed” are considered best practices. Please refer to the notes below Table A-1 with regards to distinguishing expectations for certified new small wood-fired combustors.

Table A-1: Summary of Expectations for Small Wood-Fired Combustors
Parameter Guideline A-14 Expectations
(New)		 Guideline A-14 Expectations
(Reassessed)
Wood Fuel    
1. Select wood fuel specifications Yes Yes
2. Develop wood fuel management plan Yes Yes
3. Automated start-up, shut down and feed system Yes Yes
Design Parameters    
4. Nominal load heat input capacity <3 MW <3 MW
5. Partial load heat input capacity (% of nominal load) As provided by the manufacturerA N/A
6. Air Pollution Control Equipment YesE N/A
7. Multi-zone air control with oxygen trim system Yes N/A
8. Maximum particulate matter in the flue gas, downstream of any air pollution control equipment D < 75 mg/Rm3 < 90 mg/Rm3F
Flue Gas Limits    
9. Minimum oxygen (1-hour block average) > 6.0% dry basisB > 6.0% dry basis
10. Maximum carbon monoxide (daily average)D < 400 ppmv < 400 ppmv
11. Installation Test Yes N/A
Source Testing Objectives    
12. Particulate Matter – nominal loadD < 75 mg/Rm3C < 90 mg/Rm3
13. Particulate Matter – partial loadD < 75 mg/Rm3C N/A
14. Carbon Monoxide – nominal load (1-hour average)D < 100 ppmv < 100 ppmv
15. Carbon Monoxide – partial load (1-hour average)D < 200 ppmv N/A
16. Minimum oxygen (1-hour average) > 6.0% dry basis > 6.0% dry basis
Performance Monitoring    
17. Oxygen lambda sensor (% by volume, wet basis) Yes Best Practice
18. Induced draft fan parameter Yes Best Practice
19. Fuel input or energy output (% of nominal load) Yes Best Practice
20. Flue gas temperature Yes Yes
21. Carbon monoxide (ppmv)D YesC Yes
22. Oxygen (% by volume, dry basis) YesC Yes
23. Retain performance monitoring data for at least 12 months (maximum 5-minute block averaging) Yes Yes
Inspection and Maintenance    
24. Routine inspection log and/or remote connection Yes Yes
25. Performance assessment Yes Yes

Notes:

A The partial load heat capacity for a new certified small wood-fired combustors is typically tested at 30%.

B The minimum excess oxygen (1-hour block average) for a new certified small wood-fired combustor may be 5.5% on a wet basis as recorded by the oxygen lambda sensor.

C Not applicable for a new certified small wood-fired combustor.

D Corrected to 11% oxygen, dry basis, reference conditions.

E Refer to Chapter 5.1 (f) for details of air pollution control equipment expectations, depending on the EN 303-5 (2012) Class 3, 4 or 5 rating for dust (particulate matter) and whether air pollution control equipment is required to meet the dust Class rating as specified by the manufacturer.

F This limit for particulate matter is a flue gas limit for reassessed small wood-fired combustors, not a design parameter, but it is shown here for ease of comparison with new small wood-fired combustors.

Appendix B: Tabulated Summary of Documentation Expectations

Download Table B-1: Summary of Documentation Expectations regarding Combustor Design and Performance

Appendix C: Emission Conversions and Calculations

Table C-1: Conversion Between Imperial and Metric Systems
From To Multiply by
Btu J 1055.1
Btu/hr kJ/hr 1.0551
Btu/hr W 0.29307
MM Btu/hr MW 0.29307
Pounds-mass Kilograms 0.45359

References: Perry’s Chemical’s Engineer Handbook (50th Anniversary Edition, 1984) Table 1-6, pages 1-15 to 1-17.

Notes:

  1. MM = 1 million in US customary units and Imperial British Units (e.g., 1 MM Btu = 1 million Btu).
  2. M = 1 million in metric units (e.g., 1 MW = 1 megawatt or 1 million watts).
  3. G = 1 billion in metric units (e.g., 1 GJ = 1 billion Joules).

Table C-2: Emission Conversions

a. Converting from parts per million by volume of a gaseous contaminant to milligrams per cubic metre at the same condition

Emission Concentration (mg/m3) = 21.9 × [ppmv] × [MW ⁄ (1.8 × T + 492)]

T is the temperature in °C, of the flue gases that corresponds to the (ppmv) measurement
MW = Molecular Weight of contaminant

Note: In the above-noted formula, the converted emission concentration (mg/m3) is on the same dry or wet basis and at the same flue gas conditions (e.g., % oxygen and/or % carbon dioxide) as the measured concentration (ppmv).

b. Converting from parts per million by volume of a gaseous contaminant to pounds per cubic foot at the same Conditions

Emission Concentration (lbs/ft3) = [ppmv] × {(1.369 × MW) ⁄ [1E6 × (T + 460)]}

T is the temperature in °F, of the flue gases that corresponds to the (ppmv) measurement
MW = Molecular Weight of contaminant

Note: In the above-noted formula, the converted emission concentration (lbs/ft3) is on the same dry or wet basis and at the same flue gas conditions (e.g., % oxygen and/or % carbon dioxide) as the measured concentration (ppmv).

c. Converting from pounds per standard cubic foot of a gaseous contaminant to milligrams per reference cubic metre at the same oxygen level and same wet/dry basis

Emission Concentration (mg/Rm3) = [lbs/Scf] × (35.315 ⁄ 2.2046) × (1E6) × (20 + 273) ⁄ (25 + 273)

Therefore, Emission Concentration (mg/Rm3) = [lbs/Scf] × (1.575E7)

Notes:

  1. Standard conditions (with respect to “standard ft3“ or Scf) are at 68 °F or 20 °C and reference conditions (with respect to Rm3) are at 25 °C.
  2. In the above-noted formula, the converted emission concentration (mg/Rm3) is on the same dry or wet basis and at the same flue gas conditions (e.g., % oxygen and/or % carbon dioxide) as the measured concentration (pounds/Scf).

d. Converting a measured concentration from one level of volumetric percentage of oxygen-dry in flue gas to a different volumetric percentage of oxygen in flue gas

Emission ConcentrationB = [Original Concentration]A × [(20.9 − %O2B) ⁄ (20.9 − %O2A)]

%O2B = %, by volume-dry, oxygen at the new concentration
%O2A = %, by volume-dry, oxygen at the original concentration

Example: converting 80 ppmv (dry) at 3% oxygen-dry to a concentration at 11% oxygen-dry:

Emission concentration at 11% oxygen = (80 ppmv-dry) × [(20.9 − 11) ⁄ (20.9 − 3)] = 44 ppmv-dry

e. Converting a measured concentration from one level of volumetric percentage of carbon dioxide-dry in flue gas to a different volumetric percentage of carbon dioxide in flue gas

Emission ConcentrationB = [Original Concentration]A × [(%CO2B) ÷ (%CO2A)]

%CO2B = %, by volume-dry, carbon dioxide at the new concentration
%CO2A = %, by volume-dry, carbon dioxide at the original concentration

Example: converting 100 ppmv-dry at 10% by volume-dry carbon dioxide to a concentration at 12% carbon dioxide:

Emission concentration at 12% carbon dioxide = (100 ppmv-dry) × [(12) ⁄ (10)] = 120 ppmv-dry

f. Converting a measured concentration (in mg/m3) from one flue gas temperature to another

Emission ConcentrationB = [Original Concentration]A × [(TA + 273) ⁄ (TB + 273)]

TB = Temperature, in °C, at the new concentration
TA = Temperature, in °C, at the original concentration

Example: converting 10 mg/m3 at 0 °C to a concentration at 25 °C

Emission Concentration at 25 °C = (10 mg/m3) × [(0 + 273) ⁄ (25 + 273)] = 9.2 mg/m3

Note: There is no need for a temperature correction for a concentration in ppmv because both the numerator and denominator are volume-based.

g. Converting from pounds per million Btu (a common emission factor metric used in the United States) to milligrams per reference cubic metre

When measurements of contaminant concentration (Fd) and oxygen (%O2d) are both on a dry basis, then the following conversion formula can be used:

Note: This involves the following two step conversion process:

  1. First, converting from pounds per million Btu to pounds per standard cubic foot where standard conditions are defined as 68 °F (i.e., 20 °C) and 760 mm Hg (i.e., 101.3 kPa);
  2. Second converting pounds per standard cubic foot to milligrams per Reference cubic metre where, for the purposes of this document, reference temperature and pressure are defined as 25 °C and 101.3 kPa.
Step 1: Convert pounds per million Btu to pounds per standard cubic foot

Cd = [Emission Factor in pounds per million Btu] × [(20.9 − %O2d) ⁄ (20.9 × Fd)]

  • Cd: contaminant concentration, dry basis, pounds per standard cubic foot
  • %O2d: % by volume oxygen, dry basis, that corresponds to the contaminant concentration, Cd

  • Fd: Fuel factor (volumes of combustion components per unit heat content)

    Fd = {[1E6] × [3.64 × (%H) + 1.53 × (%C) + 0.57 × (%S) + 0.14 × (%N) − 0.46 × (%O)]} ⁄ HHV

    %H: percent by weight hydrogen (as-fired, from ultimate analysis of fuel)
    %C: percent by weight carbon (as fired, from ultimate analysis of fuel)
    %S: percent by weight sulphur (as fired, from ultimate analysis of fuel)
    %N: percent by weight nitrogen (as fired, from ultimate analysis of fuel)
    %O: percent by weight oxygen (as fired, from ultimate analysis of fuel)
    HHV: Higher heating value of fuel, as fired, Btu/lb

Step 2: Convert pounds per standard cubic foot to milligrams per reference cubic metre

Cd in mg/Rm3 = [Cd in lb/Scf] × (35.315 ⁄ 2.2046) × (1E6) × (273 + 20) ⁄ (273 + 25)

Cd in mg/Rm3 = [Cd in lb/Scf] × (1.575E7)

Where, standard conditions (with respect to Scf) are at 68 °F or 20 °C and reference conditions (with respect to Rm3) are at 25 °C.

Table C-3: Summary Table of Typical Fuel Factors (Fd):

Fuel Type Fd
(dry Scf/MMBtu heat input)
Coal: Anthracite 10,100
Coal: Bituminous 9,780
Coal: Lignite 9,860
Oil 9,190
Gas (natural gas, propane, butane) 8,710
Wood 9,240
Wood Bark 9,600
Municipal Solid Waste 9,570

Note: The above fuel factors (Fd) are determined at standard conditions:
20 °C (68 °F) and 101.3 kPa (760 mm Hg)

Reference for Fuel Factor Conversion Information and Typical Fuel Factors:

US EPA, Method 19 – Determination of Sulphur Dioxide Removal Efficiency and Particulate Matter, Sulfur Dioxide and Nitrogen Oxide Emission Rates

Appendix D: Information Pertaining to Environmental Compliance Approvals Process

The websites listed below may contain information that may assist proponents to develop a small wood-fired combustor project in Ontario.

Environmental Compliance Approval in Ontario

Guide to applying for Environmental Compliance Approval

Checklist for technical requirements for a complete Environmental Compliance Approval submission

Guideline A-10: Procedure for preparing an Emission Summary and Dispersion Modelling (ESDM) report

Guideline A-11: Air dispersion modelling guideline for Ontario

Acoustic Assessment Report checklist

Appendix E: Additional Technical Information

During the development of this guideline, a significant amount of technical information was reviewed that was not used to develop regulatory instruments but may improve project performance if considered before purchasing a small wood-fired combustor. The additional technical information is summarized below for information purposes and may assist a person considering the use of a small wood-fired combustor. The rationale document prepared to accompany this guideline also contains a significant amount of technical and jurisdictional information that may be informative.

  1. Reference documents such as “Biomass Heating Project Analysis Chapter” (RetSCREEN®), “Biomass Heating” (CIBSE AM15:2014), “Emission Controls for Small Wood-Fired Boilers” (RSG Inc./BERC, May 2010) and “Particulate Matter Emissions-Control Options for Wood Boiler Systems” (BERC, 2011) are freely accessible on the internet.
  2. Where available, wood fuel with independent, third-party certification is preferred. Retaining documentation from a wood fuel supplier demonstrating compliance with a fuel standard is one approach to complying with this guideline.
  3. A project proponent should assess the availability of wood fuel and associated quantity and quality guarantees in their area. For example, having more than one wood fuel supplier within 100 km of a project site would be considered prudent if a facility does not produce its own wood fuel.
  4. For facilities seeking to use wood chips as a fuel, it is recommended that an on-site testing capability be developed to measure the moisture content of the wood chips on a periodic basis. The purpose of developing this capability is based on the fact that wood fuel moisture can be lost during sample storage and transit before analysis at an off-site laboratory and the moisture content no longer represents the “as fired” reported basis. The most widely used approach in Europe consists of using an aluminum foil pan, small oven and scale. Retaining documentation of periodic on-site wood fuel moisture tests is one approach to complying with this guideline. Refer to “Procedure to Measure Wood Fuel Moisture Content” below for a description of a procedure used to measure the moisture content of wood fuel prepared by FPInnovation.
  5. Wood chips that have been dried or “seasoned” to a moisture content of 25 to 35% typically have better combustion properties as compared with wet or “green” wood chips at 50% moisture content.
  6. A small wood-fired combustor designed to burn 50% moisture content wood chips may be able to burn lower moisture content wood chips with high efficiency but a combustor designed to burn 35% moisture content wood chips may encounter operational difficulties if 50% moisture content wood chips are used as a fuel.
  7. A combustor designed with automated continuous de-ashing is preferred, as compared with automated batch de-ashing designs, as they don’t require the combustor to temporarily cease operating to open the grate(s) to discharge the bottom ash. The automated batch de-ashing designs may emit increased levels of carbon monoxide when the grate(s) are open.
  8. To accommodate the installation of appropriate emission testing port(s) the minimum exhaust stack inner diameter should be no less than 0.15 m and a minimum diameter of 0.20 m is preferred. The Ontario Source Testing Code (June 2010, as amended) contains information pertaining to the design configuration of emission testing ports as a component of an exhaust stack.
  9. When performing a site acceptance test or tune-up, using a portable hand held combustion gas analyzer that has been designed for solid fuel burning devices is important due to the presence of particulate matter. An example of this type of analyzer is the Testo 380 that has been designed specifically to accommodate particulate matter in the flue gas.
  10. Air emissions from small wood-fired combustors can increase at partial load operation and during start-up and shut down conditions. As such, it is desirable to maintain steady state operation at or near the nominal load heat input capacity as much of the time as possible. To achieve this objective, the heating system design of a facility should be considered beyond just the small wood-fired combustor. A heating system design should include a description of how the integrated heating system components at the facility are designed to operate to meet the peak heat load as well as non-peak heat loads. This could be achieved by dividing the peak heat load into two small wood-fired combustors and/or using other devices that operate in conjunction with the small wood-fired combustor(s), such as a thermal storage tank, an auxiliary heating system and/or a peaking heating system. The description should include the estimated peak heat load served by the small wood-fired combustor(s) and the estimated monthly design heat loads to demonstrate how the small wood-fired combustor(s) is/are anticipated to modulate between nominal and partial loads or otherwise be shut down when the thermal storage tank is full or when the auxiliary heating system is operating.
  11. Certifiedfootnote 10 small wood-fired combustors are tested at partial load, which typically represents 30% of the nominal load according to EN 303-5 (2012). This emission data is informative because small wood-fired combustors used for comfort heating in a building will typically experience variable heat load demand and should be able to modulate the heat input capacity between nominal and partial load without creating significant increases in air emissions.

Procedure to Measure Wood Fuel Moisture Content

Objective: to find the moisture content percentage mc (%) (% by weight, wet basis) of a biomass sample.

Work space: This procedure should be performed in laboratory conditions.

Material and equipment:

  • Digital scale with a capacity of at least 2,000 grams and accuracy of 0.1 gram (from $350)
  • Forced air convection oven (from $700)
  • Clean sample weighing tray, able to hold at least 300 grams of biomass
  • 6 litres (> 1 kg) of biomass sample (3 replicates of at least 300 grams each)

Procedures:

Step 1
Follow the procedures for Separating Biomass Samples to separate 3 replicates of at least 300 grams each from 1 sample of at least 1 kg of biomass.

Step 2
Weigh the empty sample tray and record its weight (tare) mt.

Step 3
Load the material of a replicate into a weighing tray. Weigh the loaded tray and record the weight mwet.

Step 4
Load the tray into the oven and set to 105°C. Keep the tray in the oven until constant mass is obtainedfootnote 11.

Step 5
Weigh the loaded tray and record the weight of the dry material mdry.

Step 6
Calculate moisture content mc (%) according to the following formula:
mc (%) = [(mwet − mdry) ⁄ (mwet − mt)] × 100

Step 7
Analyze the 3 replicates and report the average.

Appendix F: Summary of Wood Fuel Specifications and NRCan Bulletins

Wood Pellets

Standards

CAN/CSA-ISO 17225-2:15, as amended

Solid biofuels – Fuel Specifications and classes – Part 2: Graded wood pellets – standard must be purchased.

This standard is a voluntary National Standard of Canada that is produced by the CSA Group. The standard was adopted without modification from the International Organization for Standardization’s Standard 17225- 2:2014, first edition 2014-05-01. It is intended to be used in conjunction with CAN/CSA-ISO 17225-1:15 (as amended), Solid biofuels - Fuel specifications and classes – Part 1: General requirements (adopted from ISO 17225-1:2014).

Accessed through the CSA Group’s website (accessed November 2015).

United States Pellet Fuels Institute (PFI) Standards Program

PFI is a non-profit North American trade association that represents the densified biomass fuel industry. The PFI Standards Program is available for voluntary use in Canada. It is a third party accredited program that provides specifications for residential and commercial-grade fuel.

Documents that outline the PFI Standards Program can be accessed through the PFI website (accessed November 2015)

Certification Systems

The Wood Pellet Association of Canada (WPAC) is the Canadian Licensor for the ENplus wood pellet certification system. The CANplus wood pellet trademark is owned by WPAC and was launched in 2013. The CANplus system is to certify wood pellets developed in Canada. Third party certification is recognized in Canada, the United States and Europe.

Details of each certification system are summarized in handbooks which can be accessed through WPAC's website (accessed November 2015).

Wood Chips

Standards

CAN/CSA-ISO 17225-4:15, as amended

Solid biofuels - Fuel specifications and classes - Part 4: Graded wood chips – standard must be purchased.

This standard is a voluntary National Standard of Canada that is produced by the CSA Group. It is an adoption without modification of the identically titled International Organization for Standardization’s Standard 17225-4, first edition, 2014-05-01. It is intended to be used in conjunction with CAN/CSA-ISO 17225-1:15 (as amended), Solid biofuels - Fuel specifications and classes – Part 1: General requirements (adopted from ISO 17225-1:2014).

Accessed through the CSA Group’s website (accessed November 2015).

Wood Briquettes

Standard

CAN/CSA-ISO 17225-3:15, as amended

Solid biofuels - Fuel specifications and classes - Part 3: Graded wood briquettes – standard must be purchased.

This standard is a voluntary National Standard of Canada that is produced by the CSA Group. It is an adoption without modification of the identically titled International Organization for Standardization’s Standard 17225-4, first edition, 2014-05-01. It is intended to be used in conjunction with CAN/CSA-ISO 17225-1:15 (as amended), Solid biofuels - Fuel specifications and classes – Part 1: General requirements (adopted from ISO 17225-1:2014). Requires payment.

Accessed through the CSA Group’s website (accessed November 2015).

Natural Resources Canada Solid Biofuels Bulletins

The NRCan bulletins are available through the NRCan website (accessed October 2016).