Control air emissions from large wood-fired combustors

1. Purpose and introduction

The purpose of Guideline A-13: Guideline for Control of Air Emissions from Large Wood-Fired Combustors (≥ 3 MW) is to provide guidance to applicants applying for an Environmental Compliance Approval (ECA) under section 20.2 of the Environmental Protection Act (EPA) for large wood-fired combustors with a heat input capacity of 3 megawatts or greater.

This guideline will set out minimum expected requirements that the director may apply when exercising his or her discretion while considering applications on a case-by-case basis. 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 expected requirements, the application of which remain subject to the discretion of the director.

During the review of an application for an ECA, the director under section 20.3 of the Act considers the requirements set out in relevant regulations as well as all applicable Ontario Ministry of the Environment, Conservation and Parks (ministry) guidelines and policies. With this in mind, applicants for ECAs for large wood-fired combustors should review this guideline with care while preparing their applications and supporting information for consideration by the director.

In addition, this guideline may provide guidance to persons operating large wood-fired combustors in Ontario, as the requirements in this document may be incorporated into abatement or enforcement tools, where appropriate.

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The requirements of this guideline are compulsory to the extent that they are contained in conditions of an ECA issued under section 20.3 of the Act or other legally binding instrument.

Finally, 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 identified in the Environmental Protection Act or Ontario Regulation 419/05, the legislative requirements shall determine the appropriate approach.

2. Definitions and abbreviations

The following definitions apply for the purposes of this guideline.

Air pollution control equipment

Equipment that is designed to decrease emissions to the atmosphere of one or more contaminants that are present in the flue gas stream.

Act

The Environmental Protection Act, RSO 1990, c E.19.

Combustion air

Air that is conveyed into the combustor to provide oxygen for the combustion process.

Combustor

A device in which combustible material is oxidized resulting in release of heat and products of combustion and includes a furnace section and a heat exchanger section downstream of the furnace.

Commissioning period

The 90-day period following the first start-up of a new or significantly modified large wood-fired combustor.

Dioxins, furans and dioxin-like PCBs

The same meaning as in subsection 1(1) of Ontario Regulation 419/05 and is calculated in accordance with subsection 1(2.02) of Ontario Regulation 419/05, as amended.

Director

Director appointed under section 20.3 of the Environmental Protection Act or other director that issues a legally binding instrument.

District manager

In respect to the facility, the district manager of the local ministry office located closest to the facility.

ECA

Environmental Compliance Approval, as defined in subsection 1(1) of the Ontario Environmental Protection Act R.S.O. 1990, as amended.

Electrostatic precipitator

A device which removes dust or other finely divided particles from a gas by charging the particles inductively with an electric field then attracting them to highly charged collector plates.

Existing large wood-fired combustor

A large wood-fired combustor that has not undergone a significant modification and meets one of the following criteria:

1. construction of the large wood-fired combustor was completed or began on or before January 1, 2015
2. an application was made on or before January 1, 2015, for an environmental compliance approval in respect of the large wood-fired combustor.

Fabric filter

A device that uses fabric bags or cartridge filters to remove particulate from a gaseous stream prior to its discharge of the gaseous stream into the air.

Flue gas

A gas that is generated by a combustion process.

Furnace

The part of a combustor where combustion takes place.

Furnace volume

The volume is calculated from the top of the wood pile or the top operating burner level to the furnace exit.

Guideline

Guideline A-13: Guideline for Control of Air Emissions from Large Wood-Fired Combustors (≥ 3 MW) published by the ministry in January 2015, as amended.

Heat input capacity

The ability of a large wood-fired combustor to combust a maximum amount of fuel based on the physical design of the large wood-fired combustor and is calculated by multiplying the flow rate of the fuel by the higher heating value of the fuel.

Higher heating value

The amount of heat released during the complete combustion of a unit quantity of fuel. In contrast, the net or lower heating value is obtained by subtracting the latent heat of vapourization of the water vapour formed by the combustion.

Hogged wood fuel

An unprocessed mix of coarse chips of bark and wood fibre generated by grinding or chipping action.

Large wood-fired combustor

A combustor that has a heat input capacity of at least three megawatts and that is designed to burn wood fuel. Refer to section 3.0 for information on the applicability of this guideline to large wood-fired combustors that may burn municipal waste.

mg/Rm³

Milligrams per reference cubic metre at reference conditions.

Ministry

The ministry of the Government of Ontario responsible for the Act and its regulations and includes all officials, employees or other persons acting on its behalf.

Municipal waste

Has the same meaning as in Ontario Regulation 347 R.R.O. 1990, as amended.

MW

Megawatt, a unit of power equal to 1 million joules per second. One megawatt sustained for 1 hour corresponds to 3600 megajoules of energy.

New large wood-fired combustor

A wood-fired combustor, the construction of which began after January 1, 2015 and no application was made on or before that date for an ECA in respect of the large wood-fired combustor.

Record

A written procedure, measurement result, written notification, table, report, document, written practice, or an update to any of the preceding.

Reference conditions

Defined as a temperature of 25 degrees Celsius and a pressure of 101.3 kilopascals.

Residence time

The average amount of time that a gas spends in a furnace and is calculated by dividing the furnace volume by the volumetric flow rate of the gas going through the furnace.

Shut-down

An operating condition during which the operation of a source of contaminant is decreased from normal operating conditions to an inoperative state.

Significant modification

A modification that meets all the following requirements:

• increased the intensity (that is, increased the mass of emissions per unit heat input capacity) of emissions of suspended particulate matter or benzo[a]pyrene:
• increased the heat input capacity of the large wood-fired combustor
• resulted in the large wood-fired combustor having a heat input capacity of greater than 20 MW
• began after July 1, 2016, and no application was made on or before that date with respect to the modification

Significantly modified large wood-fired combustor

A large wood-fired combustor that has undergone a significant modification.

Start-up

An operating condition during which the operation of a source of contaminant is increased from an inoperative state to normal operating conditions.

Suspended particulate matter

Particulate matter that has an aerodynamic diameter of less than 44 microns.

Suspension firing

A process that combusts small fuel particles (for example, less than 4mm in size) in which the fuel and supporting air is introduced into the furnace via dedicated burners mounted on the furnace walls or corners.

Wet scrubber

A device that is used to separate and collect gaseous, liquid and particulate pollutants from a gas stream into a water-based solution.

Woodchip

A piece of wood of a defined size, cut or chipped from a larger piece of wood.

Wood fuel

Fuel comprising one or more of the following materials: hogged wood fuel, wood chips, wood pellets, bark, sawdust, woodwaste, cellulosic plant material, paper and paper sludge.

Wood pellet

A pellet made from wood fuel or woodwaste.

Woodwaste

Has the same meaning as in Ontario Regulation 347 R.R.O. 1990, as amended.

In this guideline, a reference to:

• a percentage by weight, as fired
  is a reference to a percentage that is calculated based on the weight of the fuel as it is introduced to a large wood-fired combustor
• concentration
  is a reference to a concentration by volume, on a dry basis, corrected to 11% oxygen-dry in the flue gas
• percentage of oxygen
  is a reference to percentage oxygen by volume on a dry basis

3. Applicability

The purpose of this guideline is to promote the minimization of air pollution from large wood-fired combustors as defined in this guideline. This guideline will set out requirements that may be considered as conditions in an ECA or as part of other legally binding instruments such as orders.

Recall that, by definition, a large wood-fired combustor must be designed to burn wood fuel. Combustors that burn fuel other than wood fuel are governed by rules other than this guideline. In particular, it should be noted that a large wood-fired combustor that burns waste that is predominantly wood but that does not meet the definition of woodwaste is expected to be controlled, designed and operated in accordance with Guideline A-7: Air Pollution Control, Design and Operation Guidelines for Municipal Waste Thermal Treatment Facilities, October 2010, as may be amended from time to time.

The recommendations in this guideline vary according to 3 types of large wood-fired combustors:

1. existing large wood-fired combustors
2. significantly modified large wood-fired combustors
3. new large wood-fired combustors

It should be noted that several of the suggested requirements phase in over time for existing and significantly modified large wood-fired combustors. The timing for such requirements will be set out in the relevant sections and is summarized in the table in Appendix A. Proponents of ECA applications may also request that the phased-in requirements become applicable earlier than the dates outlined in this guideline.

Where this guideline indicates that a requirement has phased in and may be considered in reviewing an ECA application for a particular type of large wood-fired combustor, the requirement may also be considered as a condition in another legal instrument (for example, an order) ^{footnote 1[1]}.

4. Design and operating requirements for large wood-fired combustors

This section includes minimum design and operating requirements that will be considered when reviewing ECA applications for new, significantly modified, and existing large wood-fired combustors. Having regard to these considerations while reviewing an ECA application for a large wood-fired combustor will help ensure effective/complete combustion of the wood fuel (for example, minimize excessive concentrations/variation in carbon monoxide (CO) levels) and minimize the emission of unburned hydrocarbons including polyaromatic hydrocarbons such as benzo[a]pyrene.

4.1 Design and expected performance information

This section recommends that information on the design and expected performance of a large wood-fired combustor be submitted as part of an ECA application. The submission of this information will assist the director in assessing whether the large wood-fired combustor is capable of meeting the guideline requirements.

The following information should be submitted in an ECA application made in respect of a new or significantly modified large wood-fired combustor:

• a tabulated summary of the design and expected performance of the large wood-fired combustor
• a side-sectional schematic of the combustor including an illustration of the method of introduction of wood fuel to the furnace (for example, fluidized bed, travelling grate, burner etc.) identification of points of introduction of combustion air; and furnace dimensions used to estimate furnace volume
• a tabulated summary of the characteristics of the wood fuel (including wood fuel sizing, moisture content and any relevant information on mixed fuel usage)
• a tabulated summary of the design and expected performance of the air pollution control equipment associated with the large wood-fired combustor

It is recommended that ECAs for new or significantly modified large wood-fired combustors contain a condition requiring that the following operating data be made available, upon request by the district manager, to the ministry:^{footnote 2[2]}

• flue gas temperature leaving the combustor (that is, downstream of the heat exchanger or where measured)
• percent by volume (dry) excess oxygen in the flue gas
• percent by volume (dry) carbon monoxide in the flue gas

The operating data can be compared with the original design information and will assist in ensuring that the large wood-fired combustor is operating as intended.

For more detail with respect to the above-noted submission requirements, refer to tables B-1, B-2, B-3 and B-4 in Appendix B of this guideline.

4.2 General design and operating parameters

4.2.1 Furnace residence time and furnace exit flue gas temperature for new large wood-fired combustors

Minimum design and operating parameters for residence time, combustion temperature and combustion air distribution are recommended to provide guidance to proponents designing large wood-fired combustors to ensure that the design will achieve high combustion efficiencies.

It is expected that detailed engineering drawings, specifications and calculations be submitted to the ministry in support of ECA applications for new large wood-fired combustors. The submission is not expected to include final “construction” drawings, but it should include details necessary to:

• verify residence time estimates
• identify points where combustion air is introduced
• indicate monitoring locations for key parameters including, temperature, oxygen, carbon monoxide and opacity (as required)

To promote good combustion, it is recommended that a new large wood-fired combustor be designed to operate in a manner that ensures the flue gas in the furnace (as measured at the furnace exit) attains a temperature of at least 1000 degrees Celsius for a residence time of at least 1 second. The origin of this time-temperature window shall be taken as the lowest point of fuel delivery into the furnace.

Operating at lower furnace exit flue gas temperature may also be acceptable as long as all the following requirements are met:

• the unit is designed to achieve a minimum combustion temperature of 1000 degrees Celsius for a residence time of at least 1 second
• the CO and O₂ requirements (refer to section 8.3) are maintained
• the temperature measurements (refer to section 8.3) provide evidence that intended operating temperatures within the furnace are being maintained

Other combinations of these design criteria (for example, lower design temperature but longer residence time) may also be considered as long as all other conditions of the guideline are met. Proposals for technologies that deviate from the recommended combustor residence time or furnace exit temperature are expected to include detailed justification for any alternative designs. Additional testing and long-term monitoring may be required to verify the performance of the alternative designs. Table 4-1, below, provides a matrix combination of alternate minimum design combustion temperatures and residence times that would likely be found acceptable by the ministry.

Special case – fluidized bed designs: In fluidized/bubbling/circulating bed technology the wood fuel is introduced into a medium, such as sand, that can improve combustion dynamics (for example, improved temperature homogeneity and mixing of the fuel with combustion air). This technology generally operates at lower design combustion temperatures as a means to preserve system components and in recognition of the improved combustion dynamics. It is recommended that new large wood-fired combustors, that employ a fluidized bed technology, be designed to achieve a minimum combustion temperature of 800 degrees Celsius for a minimum residence time of 1 second.

4.2.2 Combustion air requirements

It is recommended that combustion air systems for all large wood-fired combustors be designed and operated to achieve the following:

• A large wood-fired combustor should be designed to ensure that the air distribution within the large wood-fired combustor can be controlled. Ideally, control systems shall have the capability of adjusting the distribution of combustion air in order to provide adequate mixing of the gases and the desired level of residual oxygen in the exhaust gases under all load conditions.
• A large wood-fired combustor should be designed such that the amount of combustion air entering the combustor can be controlled to ensure that an oxygen level in the flue gas is not less than 4% by volume on a dry basis on a 3-hour rolling average basis.

Special case – suspension burners: In the case of large wood-fired combustors employing suspension burners for sawdust or similar wood fuel comprised of small particles, the design and operating levels of combustion air should be maintained such that the percent oxygen in the flue gas is not less than 1.5% by volume on a dry basis on a rolling 3-hour average basis.

4.2.3 Requirements for fuel management ^{footnote 3[3]}

Fuel quality is a critical component for ensuring efficient combustion. In order to ensure that fuels being supplied to the large wood-fired combustor are appropriate and are managed in a manner that maintains the quality and characteristics of the fuel, facilities would be expected to prepare, implement and maintain a formal fuel management plan.

The director may consider imposing a condition in an ECA related to a large wood-fired combustor that would require the following information to be included in a wood fuel management plan:

1. A list of the types of wood fuel that may be stored at the facility.
2. For each type of wood fuel listed in item 1, an identification of parameters that will demonstrate the storage quality of the wood fuel, including size and moisture content.
3. For each parameter identified under item 2, a determination of a range of values within which the wood fuel will be considered of acceptable quality for storage at the facility.
4. A procedure to ensure that the wood fuel is tested to ensure that the value for each parameter identified under item 2 is within the range determined under item 3 for the parameter.
5. A procedure to ensure the wood fuel is inspected on a regular basis and that the inspection includes an inspection of the pile and of the feed system.
6. A procedure to ensure that wood fuel not considered acceptable for storage at the facility is rejected and not stored at the facility.
7. An indication of the maximum time that a wood fuel may be stored at the facility.
8. A pile turn-over procedure to ensure that wood fuel that has been at the facility longest is used first.
9. A procedure to ensure that records are prepared and retained at the facility that set out:
   1. the quantity of wood fuel purchased by the facility and the source from which it was purchased
   2. the quantity of wood fuel generated at the facility
   3. the quantity of wood fuel rejected for storage at the facility, in accordance with paragraph 6, and the reasons for the rejection

4.2.4 Exemptions during start-ups and shut-downs

The director may consider clarifying in an ECA related to a large wood-fired combustor that certain requirements (for example, the requirements in sections 5,6 and 7, inclusive) of this guideline do not apply during the following periods:

1. the commissioning period of the large wood-fired combustor
2. the period during which the large wood-fired combustor is starting up or shutting down if the following is met:
   1. the shut-down does not last for more than 6 hours
   2. the start-up does not last for more than 24 hours
   3. the start-up or shut-down is conducted according to a written plan that minimizes discharges into the air during the period of start-up or shut-down

However, all measurements required by Continuous in-stack monitoring (section 8.2) and Continuous flue gas monitoring (section 8.3) are expected to be recorded during the start-up and shut-down period.

5. Flue gas concentration requirements

This section of the guideline sets out limits that are intended to ensure good combustion conditions.

5.1 Carbon monoxide, flue gas limit

Table 5-1 sets out limits for the concentration of carbon monoxide at the exit of a large wood-fired combustor (or at a location approved by the director).

5.2 Notification of exceedances and record keeping

It is recommended that the director consider imposing the following requirements in conditions of an ECA related to a large wood-fired combustor:

• Notification of Exceedances: conditions that require the owner and operator of a large wood-fired combustor to ensure that the local district manager is notified, no later than five days in writing (via email or letter) of any exceedance of the carbon monoxide limits outlined in table 5-1. If notification is required to be given, it is recommended that a condition of the ECA require that the following information, as it relates to the period of exceedance, be recorded:
  • the type of wood being processed
  • the moisture content of the material
  • continuous emission monitor data
  • a description of actions taken to mitigate and reduce the carbon monoxide emissions

This section is not applicable if a facility is operating under a written abatement plan for carbon monoxide per section 5.3 of this guideline.

• Record keeping: conditions that require the owner and operator of a large wood-fired combustor to maintain records that contain the above-noted information for any exceedance of the carbon monoxide limits outlined in table 5-1. The records should be in electronic format and retained for a period of not less than 3 years. Refer to section 9 for additional record-keeping requirements related to combustor performance.

The director may consider allowing, at the discretion of a ministry district manager, to use a general plan of notification from the facility to address multiple exceedances of the applicable limit for carbon monoxide in the flue gas.

5.3 Written abatement plan for carbon monoxide

It is recommended that the director consider imposing the following requirements in conditions of an ECA related to a large wood-fired combustor:

• Abatement plan development and implementation: If there is information that indicates that the carbon monoxide in the flue gas of a large wood-fired combustor is exceeding the applicable limit set out in table 5-1 of this guideline, the owner and operator shall ensure that a written abatement plan that includes steps to be taken in order to prevent discharges of carbon monoxide from exceeding the concentration limit set out in section 5.1 of this guideline is developed and implemented.
• The director may consider allowing, at the discretion of a ministry district manager, to use a common written abatement plan to address multiple exceedances of the applicable limit for carbon monoxide in the flue gas.

6. Tune-ups of the wood-fired combustor every 2 years

It is recommended that the director consider imposing an ECA condition to require a tune-up of a large wood-fired combustor once in every 2-year period. The purpose of a combustor tune-up is to assist in achieving effective combustion. A tune-up includes an assessment of combustor operation, such as the relationship between continuous measurements of carbon monoxide and controlling the amount of combustion air introduced to the combustor, and may result in adjustment of key operating set-points (for example, oxygen in the flue gas).

It is recommended that the director consider imposing, in conditions of an ECA related to a large wood-fired combustor, that a report of each biennial tune-up be retained for a minimum of 5 years and be made available for review by ministry staff upon request.

For more detail with respect to suggested combustor tune-up requirements refer to table B-4 in Appendix B of this document.

7. In-stack concentration limits

7.1 Suspended Particulate Matter

Special case — direct contact wood-fired dryers: The above-noted suspended particulate matter emission limits are not applicable for ECA applications that include direct contact wood-fired dryers: for these units, only the suspended particulate matter point of impingement standard in Ontario Regulation 419/05 applies.

7.2 Nitrogen oxides (NOx)

When reviewing an ECA application with respect to a new large wood-fired combustor that has a heat input capacity of at least 100 MW, it is recommended that the director consider imposing an in-stack limit to ensure that the concentration of nitrogen oxide does not exceed 198 mg/Rm³ corrected to 11% oxygen — dry on a 24-hour rolling average basis.

7.3 Total dioxins, furans and dioxin-like PCBs (toxic equivalency)

Recall that, in general, this guideline only applies to large wood-fired combustor that burn wood fuel. For details refer to section 3. Despite this general premise, a director may wish to rely on elements of this guideline when reviewing an ECA application that relates to a large wood-fired combustor that may burn municipal waste that is predominantly wood (but does not meet the definition of woodwaste) in combination with wood fuel. It is recommended that this guideline only apply to situations where such waste comprises no more than 7.5% by weight, as fired, of the total fuel burned.

If the director decides to rely on elements of this guideline when reviewing an ECA application with respect to a large wood-fired combustor that meets the description above, it is recommended that the director consider imposing an in-stack limit to ensure that the concentration of total dioxins, furans and dioxin-like PCBs (toxic equivalency) do not exceed 80 picograms per reference cubic metre (80 pg/Rm³), corrected to 11% oxygen — dry content. It is recommended that compliance with this limit be determined through ministry validated stack testing. The toxic equivalent concentration shall be determined based upon the WHO 2005 toxic equivalency factors (TEFs) presented in Appendix D.

8. Monitoring requirements

8.1 Periodic in-stack concentration monitoring

It is recommended that the director consider imposing monitoring conditions in ECAs that relate to any large wood-fired combustor (existing, significantly modified or new) that burns only wood fuel. In particular, it is recommended that the conditions require the following parameters to be measured:

• SPM: Stack testing requirement, at an operating condition that will result in maximum emissions, for suspended particulate matter first within 12 months of commencement of operations and thereafter every 4 years.
• BaP: Stack testing for benzo[a]pyrene shall also be conducted first within 12 months of commencement of operation and thereafter every 4 years.

If the director is reviewing an ECA application with respect to a large wood-fired combustor that may burn municipal waste that is predominantly wood, but does not meet the definition of woodwaste, in combination with wood fuel where such waste does not comprise more than 7.5% by weight, as fired, of the total fuel burned, it is recommended that a condition to complete annual stack testing for the following parameters be considered:

• suspended particulate matter
• benzo[a]pyrene
• total dioxins, furans and dioxin-like PCBs (reported as toxic equivalency)
• any metals that may be present in the wood either due to treatment, intentional addition or as a result of contamination

The director may impose a condition in the ECA requiring that all stack tests be validated by the ministry and stack test reports be submitted to the ministry within 4 months of the completion of the stack test.

8.2 Continuous in-stack monitoring

The director may consider imposing a condition in an ECA requiring that in-stack opacity be continuously monitored and recorded (where measurements are taken on a minute-by-minute), if the application for the ECA relates to a large wood-fired combustor that meets the following criteria:

• the large wood-fired combustor is a new or significantly modified large wood-fired combustor
• the large wood-fired combustor has a heat input capacity of at least 50 MW
• no wet scrubber is associated with the large wood-fired combustor
• the large wood-fired combustor is not used as a direct contact dryer

Particle counting devices, such as some bag leakage detection devices installed downstream of a fabric filter air pollution control device, can be proposed as an alternative to the above-suggested condition.

In addition, it is recommended that new large wood-fired combustor having a heat input capacity of at least 100 MW, be equipped with devices to continuously monitor and record nitrogen oxides.

Reporting of opacity exceedances shall be in accordance with the requirements of Ontario Regulation 419/05. For more information on opacity exceedances, please refer to the Technical Methods for Opacity under Ontario Regulation 419/05 Technical Bulletin.

All continuous emission monitoring devices and sampling locations must be approved by the ministry (for example, during the ministry review of an application for an ECA approval). In summary, it is recommended that the director impose conditions on ECAs which indicate that proponents submit (to the manager of Technology Standards Section, Technical Assessments and Standards Development Branch) a plan for the approved installation, operation and maintenance of the above-noted continuous in-stack monitoring devices.

8.3 Continuous flue gas monitoring

It is recommended that the director consider imposing, in an ECA that relates to any large wood-fired combustor, a requirement to continuously monitor and record the following parameters:

• The undiluted percentage of oxygen by volume, on a dry basis, in the flue gas leaving the combustor (measured and recorded in dry flue gas; or in wet flue gas and converted and recorded on a dry basis).
• The undiluted concentration of carbon monoxide in the dry flue gas leaving the combustor (measured and recorded in dry flue gas; or in wet flue gas and converted and recorded on a dry basis). It is recommended that the measurements of oxygen and carbon monoxide are conducted at the same location.
• The temperature of the flue gas leaving the combustor (downstream of the heat exchanger or boiler-bank). This temperature measurement can then be compared to design and expected performance information, from the manufacturer, for heat exchanger exit temperature and furnace exit temperature.

All continuous emission monitoring devices and sampling locations must be approved by the ministry. In summary, it is recommended that the director impose conditions on ECAs which indicate that proponents submit (to the manager of Technology Standards Section, Technical Assessments and Standards Development Branch) a plan for the approved installation, operation and maintenance of the above-noted continuous in-stack monitoring devices.

Special case – direct contact or indirect contact wood-fired dryers: The director may consider alternative approaches (for example, periodic stack testing of carbon monoxide) for continuous measurement of oxygen and/or carbon monoxide and/or temperature in the flue gas where it can be demonstrated that the presence of excessive amounts of wood fibre in the flue gas of a direct contact or indirect contact dryer may result in unreasonable challenges to the operation and maintenance of these continuous monitors.

Note: For clarity, the oxygen, carbon monoxide and temperature monitors may be installed either downstream of the furnace or downstream of the combustor’s main heat exchanger. The oxygen and carbon monoxide monitors may also be installed downstream of an economizer type heat exchanger (which is sometimes included downstream of the combustor’s main heat exchanger) but it is not recommended that the oxygen and carbon monoxide monitors be installed downstream of an air heater because ambient air in-leakage can occur through an air heater.

9. Summary reports on combustor performance, updated every 2 years

• It is recommended that the director require in a condition of an ECA that the owner and operator of a large wood-fired combustor ensure that records are prepared at least once in every 2-year period. The records should summarize the relevant requirements imposed on the large wood-fired combustor and should include, as applicable, the records described below.
• For each parameter where, in section 8 of this guideline, testing or continuous monitoring is recommended, the following statistical information:
  • the maximum measurement taken over the 2-year period
  • the minimum measurement taken over the 2-year period
  • the average measurement taken over the 2-year period.
• A record of all notices required to be given under section 5.2 of this guideline during the 2-year period.
• The dates during the 2-year period when start-up or shut-down of a large wood-fired combustor occurred ^{footnote 7[7]}.
• A record of approved fuel management procedures required by section 4.2.3 of this guideline and details of instances where these were not followed.
• For each air pollution device associated with a large wood-fired combustor, the dates during the 2-year period when the device did not operate.
• A record of the results from the biennial tune-up required under section 6 of this guideline.

Appendix A

Appendix B

Note: R means reference conditions (25 °C and 101.3 kPa)

Table B-4: Combustor tune-ups every 2 years

Adherence to manufacturer’s specifications and directions and to safety requirements takes precedence over the combustor tune-up requirements outlined below. An inspection and preventative maintenance program that is consistent with professional’s recommendations should also be implemented.

Physical inspection of the following:

• fuel handling equipment
• fuel distribution equipment
• air dampers
• air measurement devices
• grates or burners

Review of equipment performance:

• CO and O₂ data
• airflow data
• steam flow to bark data
• air to fuel ratio data and verify operating within design criteria
• CEM (O₂, CO) calibration data and performance

Conduct combustion test:

• visual observation of combustion
• monitor and adjust excess air ratio
• monitor oxygen and CO data

Note: The source of a professional’s recommendations mentioned should be one the following documents:

• the manufacturer’s operating manual
• a letter from the manufacturer, specifying the recommended inspection or maintenance
• a letter from a professional engineer who has experience with the technology specifying recommended inspection or maintenance practices and the rationale for the specification

Appendix C

Emission conversions and calculations

Reference: Perry’s Chemical’s Engineer Handbook (50^th 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 (for example, 1 MM Btu = 1 million Btu).
2. M = 1 million in metric units (for example, 1 MW = 1 megawatt or 1 million watts).
3. G = 1 billion in metric units (for example, 1 GJ = 1 billion Joules).

Table C-2: Emission conversions

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

   Emission Concentration (mg/m³) = 21.9 × [ppmv] × (MW/(1.8x×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 (for example, % oxygen and/or % carbon dioxide) as the measured concentration (ppmv).

2. Converting from parts per million by volume of a gaseous contaminant to pounds per cubic foot at the same conditions:

   Emission Concentration (pounds/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 (pounds/ft³) is on the same dry or wet basis and at the same flue gas conditions (for example, % oxygen and/or % carbon dioxide) as the measured concentration (ppmv).

3. 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) = 
   [pounds/Scf] × (35.315/2.2046) × (1E6) × (20+273)/(25+273) 
   Therefore, Emission Concentration (mg/Rm³) = [pounds/Scf] × (1.575E7) 

   Notes:

   1. Standard conditions (with respect to standard cubic foot 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 (for example, % oxygen and/or % carbon dioxide) as the measured concentration (pounds/Scf).

4. 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 Concentration_B = [Original Concentration]_A × (20.9 − %O_2B)/ (20.9 − %O_2A)

   %O_2B = percent, by volume-dry, oxygen at the new concentration 
   %O_2A = percent, 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

5. 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 Concentration_B = [Original Concentration]_A × (%CO_2B)/(%CO_2A)

   
   %CO_2B = percent, by volume-dry, carbon dioxide at the new concentration 
   %CO_2A = percent, 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

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

   Emission Concentration_B = [Original Concentration]_A × (T_A+273)/(T_B+273)

   T_B = Temperature, in °C, at the new concentration 
   T_A = 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.

7. 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 (%O_2d) 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 (that is, 20 °C) and 760 mm Hg (that is, 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:

   C_d = [Emission Factor in pounds per million Btu] × [(20.9 - %O_2d)/(20.9 × F_d)]

   • C_d: contaminant concentration, dry basis, pounds per standard cubic foot
   • %O_2d: percent by volume oxygen, dry basis, that corresponds to the contaminant concentration, C_d
   • F_d: Fuel factor (volumes of combustion components per unit heat content)

   F_d = [1E6] × [3.64×(%H) + 1.53x(%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:

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

   C_d in mg/Rm³ = [C_d 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.

Note: The above fuel factors (F_d) 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 of sulphur dioxide removal efficiency and particulate matter, sulfur dioxide and nitrogen oxide emission rates

Appendix D

Application of the air standard for dioxins, furans, and dioxin-like PCBs requires the calculation of the total toxicity equivalent (TEQ) concentration contributed by all dioxin-like compounds in the mixture. This is a legal requirement set out in section 1 (2.0.2) and Schedule 8 of Ontario Regulation 419/05 and is similarly applicable to this guideline (when municipal waste is co-fired with wood).

Table D-1 below lists 29 specific dioxins, furans, and dioxin-like PCBs (along with the corresponding WHO2005 toxic equivalency factors (TEFs)) to which the new standards would apply. The following formula should be used in order to meet the requirement in the regulation of calculating the total concentration of dioxins, furans and dioxin-like PCBs:

• A = Σ(B × C), where,
• A = the amount (or concentration) of total dioxins, furans and dioxin-like PCBs in TEQ
• B = the amount (or concentration) of each dioxin-like compound listed in table 2
• C = the corresponding TEF for each dioxin-like compound listed in table 2

For the purpose of calculating the total TEQ concentration for a mixture of dioxin-like compounds, a value of half the minimum detection limit (MDL) should be substituted for concentrations less than the MDL.

The above-noted table includes a list of specific types of dioxins, furans and dioxin-like polychlorinated biphenyl compounds and a factor, published by the World Health Organization (WHO) that identifies the relative toxicity of each chemical compound that is identified in the table.

Appendix E

Interpretative examples for identifying significant modifications

Definition of existing large wood-fired combustor: means a large wood-fired combustor that has not undergone a significant modification and either of the following are true:

• construction of the large wood-fired combustor was completed or began on or before  January 1, 2015
• an application was made on or before January 1, 2015, for an ECA in respect of the large wood-fired combustor

Note: The requirements of this guideline will necessarily be triggered for new and significantly modified large wood-fired combustors because of the need for such combustors to obtain an ECA. However, to be clear, the requirements will not apply to an existing large wood-fired combustor unless such a combustor is the subject of an ECA application or other legal instrument (for example, order).

Example 1 – Existing large wood-fired combustor:

A facility has been operating a wood-fired combustor with a heat input capacity of 150MW for many years.

The requirements of this guideline are intended to be applicable to any wood-fired combustors having heat inputs equal to or greater than 3 MW and only intended to be applicable to existing large wood-fired combustors (refer to the above-noted definition for existing large wood-fired combustors), under one or more of the following circumstances:

1. the existing large wood-fired combustor is under-going significant modifications (refer to definition for significantly modified large wood-fired combustor, below)
2. the existing large wood-fired combustor is part of an application for ECA (for example, as part of a request for a site-wide or comprehensive ECA)
3. in the event that the ministry has issued an order, that includes some or all of the requirements in this guideline, with respect to an existing large wood-fired combustor

Definition of significantly modified large wood-fired combustor:

"Significant modification" a modification that.

• increased the intensity (that is, increased the mass of emissions per unit heat input capacity) of emissions of suspended particulate matter or benzo[a]pyrene
• increased the heat input capacity of the large wood-fired combustor
• resulted in the large wood-fired combustor having a heat input capacity of greater than 20 MW
• began after July 1, 2016 and no application was made on or before that date with respect to the modification;

"Significantly modified large wood-fired combustor" a large wood-fired combustor that has undergone a significant modification

Example 2:

A wood-fired combustor with a heat input capacity of 50 MW is proposed to be modified to increase its capacity by 50% (that is, increase by 25 MW). It is also estimated that the mass emission rate (for example, grams per second) of suspended particulate matter and/or benzo[a]pyrene will not increase, as a result of the proposed modifications, by more than 50%. The submission includes the following information to support the estimate that there will be no increase in the intensity of emissions of particulate nor benzo[a]pyrene:

• The modification proposal demonstrates that the current or modified particulate emission control equipment is capable of managing the increased inlet emissions of particulate such that any increase in outlet emissions is no greater than, proportionally, than the increase in heat input capacity for the modified combustor.
• There are enhancements to the current combustion control system that are designed to limit the emission of carbon monoxide and polyaromatic hydrocarbons (such as benzo[a]pyrene).

The large wood-fired combustor described above may not be a "significantly modified large wood-fired combustor"; assuming that the supporting technical information is sufficient to support the contention of no increase in the intensity of neither suspended particulate matter nor benzo[a]pyrene.

Example 3:

A wood-fired combustor with a heat input capacity of 15 MW is proposed to be modified to increase its capacity by 200% (that is, increase by 30 MW to 45 MW). It is also estimated that the emissions of suspended particulate matter and/or benzo[a]pyrene will not increase, as a result of the proposed modifications, by more than 100%. The submission includes the following information to support the estimate that there will be no increase in the intensity of emissions of particulate nor benzo[a]pyrene:

• The modification proposal demonstrates that the current or modified particulate emission control equipment is capable of managing the increased inlet emissions of particulate such that any increase in outlet emissions is no greater than, proportionally, than the increase in heat input capacity for the modified combustor.
• There are enhancements to the current combustion control system that are designed to limit the emission of carbon monoxide and polyaromatic hydrocarbons (such as benzo[a]pyrene).

Although the current combustor is less than 20 MW, the proposed modified unit is a large wood-fired combustor that has a heat input capacity of greater than 20 MW and it may be reasonable to assess against the definition for “significantly modified large wood-fired combustor”. However, the large wood-fired combustor described above may not be a "significantly modified large wood-fired combustor"; assuming that the supporting technical information is sufficient to support the contention of no increase in the intensity of either suspended particulate matter or benzo[a]pyrene.

Example 4:

A wood-fired combustor with a heat input capacity of 50 MW is proposed to be modified to increase its capacity by 50% (that is, increase of 25 MW). It is also estimated that the emissions of suspended particulate matter and/or benzo[a]pyrene will not increase, as a result of the proposed modifications, by more than 50%. The submission is deemed by the ministry technical reviewer to not include sufficient information to support the contention of no increase in the intensity of emissions.

The proponent will either have to provide sufficient information to support the contention of no increase in the intensity of emissions or the project may be assessed by the ministry reviewer as if the definition for significantly modified large wood-fired combustor is applicable.

Example 5:

The ministry has received a proposal, in 2025 for the capacity de-rating of a significantly modified wood-fired combustor (modified in, say, 2017) from 30 MW to 10 MW.

In this example, the general intent is that the guideline requirements that are applicable to significantly modified large wood-fired combustors would continue to apply, even after the capacity de-rating. The intent is that when an existing large wood-fired combustor undergoes a significant modification, it no longer meets the definition of an “existing large wood-fired combustor” and thus would continue to be treated as a significantly modified large wood-fired combustor. However, the director may use discretion to consider whether or not to continue to apply the guideline requirements for a significantly modified large wood-fired combustor on a site-specific basis.

Example 6:

A new large wood-fired combustor has a heat input capacity of 10 MW and undergoes a modification in 2025 to be a 30 MW large wood-fired combustor and, in this example, there is an increase in the intensity of air emissions of suspended particulate matter as a result of the proposed modifications.

In this example the modification in 2025 is, by definition, a significant modification, according to the guideline definition of significant modifications, and the requirements in the guideline for significantly modified large wood-fired combustors become applicable after the 2025 modifications (for example, the emissions limit for suspended particulate matter would be reduced from 50 to 25 mg/Rm³). As accordingly, it should be noted that it is possible for a new large wood-fired combustor to become a significantly modified large wood-fired combustor.