Guidelines for Air Emission Regulation
6. Energy plants
6.1 Introduction
The emission limit values featured in this section apply to all plants that produce power and heat. For example, a plant in which a substance is dried or concentrated by using flue gas as the source of energy, but where there is no contact between the gas and the substance/material being dried/concentrated, is considered an energy plant.
The main fuels used at energy plants in Denmark are natural gas, light fuel oil, coal, and heavy fuel oil. Renewable fuels such as biogas, straw, and wood are also used. Dust is emitted from these plants in the form of soot, oil coke, NOX, etc., and polluting components arising from impurities in the fuel. Examples of such impurities are sulphur, chlorine, and fluorine, as well as ashes containing heavy metals such as nickel, vanadium, etc.
Rules regarding the maximum sulphur content of fuels have been stipulated in order to limit emissions of SO2. These rules can be found in the Statutory Order on limitation of sulphur content in fuel for heating and transport55 and the Statutory Order on limitation of sulphur content in certain liquid fuels56.
Emissions of sulphur dioxide are normally proportional to the sulphur content of the relevant fuel. In such cases, 0.02 kg SO2 is emitted per kilo fuel used per percentage point sulphur.
Except in cases where special plants have been established to clean flue gas, emissions correspond to the content of the relevant substances in the fuel concerned. Please note, however, that some of the substances emitted into the atmosphere are also bound in cinders and ashes to a lesser extent.
It is important that all energy plants are constructed, maintained and adjusted so that the inevitable pollution of the air is reduced to a minimum. The fact that there is some correlation between the concepts of minimum pollution and maximum energy efficiency provides a double incentive to reduce pollution from energy plants.
If a energy plant has equipment for flue-gas purification or abatement, such equipment should be sufficiently effective to ensure that terms regarding emission limit values included in an approval can be met throughout the energy plant’s entire life cycle and under all normal operating conditions. This means that purification or abatement equipment at energy plants should be designed for emissions that are significantly lower than the limit values.
This section features special emission limit values from energy plants. The mass flow limits and emission limit values laid down in these Guidelines apply to all substances that are not expressly specified in connection with each item (energy plant). The C-values apply to all substances. Only in exceptional cases will it be necessary to stipulate emission limit values other than those specified for each fuel type below.
The emission limit values for NOX in this chapter apply to all NOX converted into NO2.
For combustion plants with two-channel burners and modulating burners, outlet heights are calculated at various loads. The load resulting in the highest outlet must be chosen.
Please note that the physical conditions mentioned below, e.g. calorific values, may change if the chemical composition of the fuel is changed.
6.2 Natural gas, LPG, and biogas
6.2.1 General information
Calorific value for natural gas:
| Lower calorific value: | approximately 48.6 MJ/kg or |
| approximately 39.3 MJ/normal m3. |
|
| Upper calorific value: | approximately 56 MJ/kg. |
When natural gas is burned, approximately 57 g CO2 /MJ is formed. When LPG is
burned, approximately 65 g CO2/MJ is formed.
When 1 kg natural gas57 is burned, the following approximate quantity of flue gas is formed:
Equations 9 and 10
where % O2 denotes O2 content in the flue gas, expressed as a percentage by volume. |
6.2.2 Gas motors and gas turbines using natural gas
Emissions from such plants are regulated in accordance with Statutory Order No. 720 of 5 October 1998 on the limitation of emissions of nitrogen oxides, unburned carbon hydrides and carbon monoxide from gas motors and gas turbines.
From 1 July 2003, an emission limit for formaldehyde of 10 mg/normal m3 at 5 % O2 at an efficiency (in electricity production) of 30 per cent also applies to gas motors with a total input effect of 5 MW or more. This limit value is adjusted upwards or downwards in equal proportion to the electricity efficiency.
The emission of formaldehyde from gas turbines is significantly below this limit value, and so there is no need to set an emission limit value for gas turbines.
The outlet height is determined by means of an OML calculation.
6.2.3 Combustion plants with an input effect of less than 120 kW
An input effect of 120 kW corresponds to consumption of approximately 8.6 kg natural gas per hour.
The stack must be constructed in accordance with current regulations on gas and building construction.
6.2.4 Combustion plants with a total input effect of 120 kW or more, but less than 5 MW
Before purchasing new equipment, the installation should make sure that such equipment complies with the following emission limit values:
| NOX measured58 as NO2 | = | 65 mg/normal m3 dry flue gas at 10 per cent O2. |
| CO | = | 75 mg/normal m3 dry flue gas at 10 per cent O2. |
For existing plants, up to 125 mg NOX/normal m3 dry flue gas at 10 per cent O2, measured as NO2, is acceptable.
Outlet heights are determined in accordance with current regulations on gas and construction or by means of an OML calculation.
An input effect of 5 MW corresponds to the consumption of approximately 360 kg natural gas per hour.
6.2.5 Combustion plants with a total input effect of 5 MW or more, but less than 50 MW
These plants should comply with the following emission limit values:
| NOX measured as NO2 | = | 65 mg/normal m3 dry flue gas at 10 per cent O2. |
| CO | = | 75 mg/normal m3 dry flue gas at 10 per cent O2. |
For existing plants, the environmental authorities may accept up to 125 mg NOX/normal m3 dry flue gas at 10 per cent O2 measured as NO2, if it turns out that the emission limit value must be relaxed.
The outlet height is determined by means of an OML calculation.
An input effect of 50 MW corresponds to the consumption of approximately 3.6 tonnes natural gas per hour.
Example:
Determining the emission limit value and outlet height for gas-fired plants
with an input effect of 5 MW or more, but less than 50 MW
A plant states that the emission of NOX from their boiler plant, which uses natural gas, will be less than 50 mg/normal m3. It is stated that 90 per cent of the emitted quantity of NOX is NO by weight. The rest is NO2. The approving authority approves the plant and sets a emission limit value of 65 mg NOX measured as NO2 pr. normal m3, which is the emission limit for NOX. The outlet height is determined on the basis of the assumption that half of the 65 mg NOX per normal m3 consists of NO2, see section 3.2.5.2. |
6.2.6 Combustion plants with an input effect of 50 MW or more
More detailed provisions on plants with an input effect of 50 MW or more are given in Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
For older plants, which do not fall within the scope of this Statutory Order, the various emission limits, inspection measures, etc., are set according to the BAT principle on the basis of a specific assessment, see chapter 1.
The outlet height is determined by means of an OML calculation.
6.2.7 Inspection
For gas-fired plants with an input effect of 5-30 MW, performance inspections should be used to verify compliance with the limit values for NOX and CO.
Gas-fired plants with an input effect of more than 30 MW should be fitted with measurement and regulation equipment for oxygen (O2) to control the burning process. Such plants should also be fitted with AMS equipment for NOX. In addition to this, performance inspections should be used to verify compliance with the limit value for CO.
If an emission limit value of formaldehyde is set, performance inspections should be used to verify compliance with this limit value.
For plants with an input effect of 50 MW or more, refer to Statutory Order No. 689 of 15 October
1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides, and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
6.3 Light fuel oil
6.3.1 General information
Calorific value:
| Lower calorific value: | approximately 43 MJ/kg. |
| Upper calorific value: | approximately 45 MJ/kg. |
When light fuel oil is burned, approximately 74 g CO2 /MJ is formed.
When 1 kg light fuel oil is burned, the following approximate quantity of flue gas is formed:
Equations 11 and 12
 where % O2 denotes the O2 content in flue gas, expressed as a percentage by volume. |
No emission limit values for sulphur dioxide have been given for plants that burn light fuel oil, as such emissions are proportional to the sulphur content in the oil used. A total of 0.02 kg SO2 is emitted per kg oil used per percentage point sulphur.
Rapeseed oil that has been produced specifically for burning and which is of a quality corresponding to that of light fuel oil may be burned under the rules set up in this section.
Oil combustion plants that are mainly used for domestic heating fall within the scope of the Ministry of Environment and Energy Statutory Order No. 785 of 21 August 2000 on the inspection measurement, adjustment and purification or abatement of oil combustion plants.
6.3.2 Input effect less than 120 kW
No actual emission limit values have been set for these plants.
The stack must be constructed in accordance with current building regulations.
An input effect of 120 kW corresponds to consumption of approximately 10 kg light fuel oil per hour.
6.3.3 Total input effect of 120 kW or more, but less than 5 MW
Prior to purchasing new equipment, all installations should ensure that such equipment complies with the following emission limit values:
NOX measured as NO2 = 110 mg/normal m3 dry flue gas at
10 per cent O2.
CO = 100 mg/normal m3 dry flue gas at 10 per cent O2.
For existing plants, the environmental authorities may accept up to 250 mg NOX/normal m3 dry flue gas at 10 per cent O2 measured as NO2 if it turns out that the emission limit value must be relaxed.
The outlet height is determined by means of an OML calculation.
An input effect of 5 MW corresponds to the consumption of approximately 440 kg light fuel oil per hour.
6.3.4 Total input effect of 5 MW or more, but less than 50 MW
These plants should comply with the following emission limit values:
| Dust | = 30 mg/normal m3 dry flue gas at 10 per cent O2. |
| NOX measured as NO2 | = 110 mg/normal m3 dry flue gas at 10 per cent O2. |
| CO | = 100 mg/normal m3 dry flue gas at 10 per cent O2. |
For existing plants, the environmental authorities may accept up to 250 mg NOX/normal
m3 dry flue gas at 10 per cent O2, measured as NO2, if it
turns out that it is necessary to relax the emission limit value.
The outlet height is determined by means of an OML calculation.
An input effect of 50 MW corresponds to the consumption of approximately 4.2 tonnes light fuel oil per hour.
6.3.5 Total input effect of 50 MW or more
More detailed provisions on light fuel oil fired plants with an input effect of 50 MW or more are given in Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
For older plants, which do not fall within the scope of this Statutory Order, the various emission limits, inspection measures, etc., are set according to the BAT principle on the basis of a specific assessment, see chapter 1.
The outlet height is determined by means of an OML calculation.
6.3.6 Inspection
For light fuel oil fired plants with an input effect of 5-30 MW, compliance with the limit values for NOX and CO should be checked by means of performance inspection.
Light fuel oil fired plants with an input effect of more than 30 MW should be fitted with measurement and regulation equipment for oxygen (O2) to control the combustion process, and with AMS equipment for NOX. In addition to this, performance inspections should be used to verify compliance with the limit value for CO.
For plants with an input effect of 50 MW or more, refer to Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
6.4 Heavy fuel oil
This section applies to plants that burn heavy fuel oil, orimulsion, and fuels of similar quality.
6.4.1 General information about heavy fuel oil
Calorific value:
Lower calorific value: approximately 41 MJ/kg.
Upper calorific value: approximately 43 MJ/kg.
When heavy fuel oil is burned, approximately 78 g CO2 /MJ is formed.
When 1 kg heavy fuel oil is burned, the following approximate quantity of flue gas is formed:
Equations 13 and 14
where % O2 denotes O2 content in the flue gas, expressed as a percentage by volume. |
6.4.2 Total input effect of 2 MW or more, but less than 50 MW
Heavy fuel oil, orimulsion, and other fuels of similar quality may not be used in burners with an input effect of less than 2 MW.
The following emission limit values apply to these plants:
| Dust | = 100 mg/normal m3 dry flue gas at 10 per cent O2. |
| NOX measured as NO2 | = 300 mg/normal m3 dry flue gas at 10 per cent O2. |
| CO | = 100 mg/normal m3 dry flue gas at 10 per cent O2. |
| Hg | = 0.1 mg/normal m3 dry flue gas at 10 per cent O2. |
| Cd | = 0.1 mg/normal m3 dry flue gas at 10 per cent O2. |
| The sum (S )
of: |
|
| Ni | |
| V | |
| Cr | |
| Cu | |
| Pb | = 5 mg/normal m3 dry flue gas at 10 per cent O2. |
The SO2 emission depends on the sulphur content of the relevant fuel. The
maximum sulphur content in heavy fuel oil is regulated in the Statutory Order on the
limitation of sulphur contents in fuel for heating and transport59
and the Statutory Order on the limitation of the sulphur content in certain liquid fuels60. As a result, no emission limit value for SO2
is given.
If a supplier of heavy fuel oil guarantees compliance with the above limit values for heavy metals (on the basis of the composition of the heavy fuel oil), there is no need to stipulate further requirements on such substances.
For existing plants, emission limit values are determined on the basis of emission measurements and an assessment of the possibilities for reducing emissions of NOX.
Outlet heights are determined by means of OML calculations.
6.4.3 Total input effect of 50 MW or more
An input effect of 50 MW corresponds to a consumption of 4.4 tonnes heavy fuel oil per hour.
For more detailed provisions on plants with an input effect of 50 MW or more, refer to Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
In addition to these requirements, all plants should comply with the following emission limit values:
Hg = 0.1 mg/normal m3 dry flue gas at 10 per cent O2.
Cd = 0.1 mg/normal m3 dry flue gas at 10 per cent O2.
| The sum (S )
of: |
|
| Ni | |
| V | |
| Cr | |
| Cu | |
| Pb | = 5 mg/normal m3 dry flue gas at 10 per cent O2. |
If a supplier of heavy fuel oil guarantees compliance with the above limit values for
heavy metals (on the basis of the composition of the heavy fuel oil), there is no need to
stipulate further requirements on such substances.
For older plants, which do not fall within the scope of this Statutory Order, the various emission limits, inspection measures, etc., are set according to the BAT principle on the basis of a specific assessment, see chapter 1.
The outlet height is determined by means of an OML calculation.
6.4.4 Inspection
For heavy fuel oil fired plants with an input effect of 5-30 MW, compliance with the limit values for NOX and CO should be checked by means of performance inspection.
Fuel-oil-fired plants with an input effect of more than 30 MW should be fitted with measurement and regulation equipment for oxygen (O2) to control the combustion process. Such plants should also be fitted with AMS equipment for NOX. In addition to this, performance inspections should be used to verify compliance with the limit value for CO.
Heavy fuel oil fired plants with an input effect of over 50 MW should be fitted with AMS sampling apparatus for dust, SO2, NOX, and O2. Compliance with the emission limit values for the heavy metals specified here should be checked by means of performance inspection at least twice a year.
For more detailed provisions on plants with an input effect of 50 MW or more, refer to Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
Emissions of metals may often be calculated on the basis of the metal content in the relevant fuel. In many cases, such calculations are sufficiently accurate to replace emission measurement.
6.5 Waste oil
Waste oil or oil waste is hazardous waste, but falls outside the scope of the regulations on incineration of hazardous waste, as specified in the Ministry of Environment and Energy Statutory Order No. 660 on the approval, etc., of plants incinerating hazardous waste, see Section 1 (5), 1st clause of this Order. Incineration of oil waste falls within the scope of special provisions; see Section 57 and Appendix 11 of the Ministry of Environment and Energy Statutory Order No. 619 of 27 June 2000 on Waste (the Waste Order). Waste oil may only be incinerated at plants with a thermal output of more than 1 MW.
Outlet heights are determined by means of an OML calculation.
6.5.1 Inspection
Appendix 11 of the Statutory Order on Waste states that it should be possible to provide documentation of compliance with the emission limit values, either by means of calculations or emission measurements.
Measurements of emissions should be carried out by means of performance inspection.
Waste oil fired plants with an input effect of more than 5 MW should be fitted with measurement and regulation equipment for oxygen (O2) to control the incineration process. In addition to this, plants with an input effect of more than 30 MW should also be fitted with AMS equipment for NOX.
Waste oil fired plants with an input effect of more than 50 MW should be fitted with AMS equipment for dust, SO2, NOX, and O2. As regards the substances specified in Appendix 11 of the Statutory Order on Waste, the emission limit values should be checked by means of performance inspection.
6.6 Coal
This section includes plants that burn coal, pet-coke, and lignite or other fuels of similar quality.
6.6.1 General information
Calorific value for coal:
Lower calorific value: approximately 25 MJ/kg.
Upper calorific value: approximately 26 MJ/kg.
When coal is burned, approximately 95 g CO2 /MJ is formed.
When 1 kg coal is burned, the following approximate quantity of flue gas is formed:
Equations 15 and 16
where % O2 denotes O2 content in the flue gas, expressed as a percentage by volume. |
Coal, petcoke, and lignite should not be used in new plants with an input effect of less than 5 MW.
6.6.2 Total input effect of 5 MW or more, but less than 50 MW
An input effect of 5 MW corresponds to a consumption of approximately 720 kg of coal per hour.
An input effect of 50 MW corresponds to a consumption of approximately 7.2 tonnes of coal per hour.
The following emission limit values apply to these plants:
| Dust | = 100 mg/normal m3 dry flue gas at 10 per cent O2. |
| NOX measured as NO2 | = 200 mg/normal m3 dry flue gas at 10 per cent O2. |
| CO | = 100 mg/normal m3 dry flue gas at 10 per cent O2. |
| Hg | = 0.1 mg/normal m3 dry flue gas at 10 per cent O2. |
| Cd | = 0.1 mg/normal m3 dry flue gas at 10 per cent O2. |
| HCl | = 10 mg/normal m3 dry flue gas at 10 per cent O2. |
| The sum (S
) of: |
|
| Ni | |
| V | |
| Cr | |
| Cu | |
| Pb | = 5 mg/normal m3 dry flue gas at 10 per cent O2. |
If a supplier of coal guarantees compliance with the above limit values for heavy metals
(on the basis of the composition of the coal in question), there is no need to stipulate
further requirements in connection with such substances.
The SO2 emission depends on the sulphur content of the relevant coals. The maximum sulphur content in coal and petcoke is regulated in the Statutory Order on the limitation of sulphur contents in fuel for heating and transport61. As a result, no emission limit value for SO2 is given.
The emission limit value of NOX for existing plants is determined on the basis of emission measurements and an assessment of the possibilities for reducing NOX emissions. For existing plants that are also used for the removal of noxious substances, the limit for NOX emissions should be determined on the basis of a specific assessment.
Outlet heights are determined by means of an OML calculation.
6.6.3 Input effect of 50 MW or moreFor more detailed provisions on plants with an input effect of 50 MW or more, refer to Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
In addition to these requirements, all plants should comply with the following emission limit values:
| HCl | = 10 mg/normal m3 dry flue gas at 10 per cent O2. |
| HF | = 1.0 mg/normal m3 dry flue gas at 10 per cent O2. |
| Hg | = 0.1 mg/normal m3 dry flue gas at 10 per cent O2. |
| Cd | = 0.1 mg/normal m3 dry flue gas at 10 per cent O2. |
| The sum (S )
of: |
|
| Ni | |
| V | |
| Cr | |
| Cu | |
| Pb | = 5 mg/normal m3 dry flue gas at 10 per cent O2. |
If a supplier of coal guarantees compliance with the above limit values for heavy metals
(on the basis of the composition of the coal in question), there is no need to stipulate
further requirements on such substances.
For older plants, which do not fall within the scope of the Statutory Order, emission limits, inspection, etc., is determined on the basis of specific assessment by means of the BAT principle. See chapter 1.
Outlet height is determined by means of an OML calculation.
6.6.4 Inspection
If limit values for heavy metals have been set for installations using coal-fired plants, performance inspections should be carried out to check compliance with the emission limit value for the heavy metals specified.
Coal-fired plants with an input effect of more than 5 MW should be fitted with automatic measuring equipment for measurement and registration of dust emissions in accordance with the principle of opacity or methods of similar quality. They should also be fitted with sampling apparatus and regulation equipment for O2 in order to control the burning process.
Coal-fired plants with an input effect of 5-30 MW should be monitored by means of performance inspections in order to verify compliance with the limit value for NOX. Plants with an input effect greater than 30 MW should also be fitted with AMS equipment for measurement of NOX.
Coal-fired plants with an input effect of over 50 MW should be fitted with AMS equipment for dust, SO2, NOX, and O2. The emission limit value for heavy metals specified should be monitored by means of performance inspection.
For plants with an input effect of 50 MW or more, please see Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
Emissions of metals may often be calculated on the basis of the metal content in the relevant fuel. In many cases, such calculations are sufficiently accurate to replace emission measurement.
6.7 Wood
This section addresses combustion plants using wood and waste wood complying with the purity requirements specified in the Statutory Order on biomass waste62.
6.7.1 General information
The calorific value depends on the water content. The calorific value for wood containing 25 per cent water is approximately 13.7 MJ/kg.
When 1 kg wood is burned, the following approximate quantity of flue gas is formed:
Equations 17 and 18
where % O2 denotes O2 content in the flue gas, expressed as a percentage by volume. |
6.7.2 Wood-fired stoves
If a stove causes significant pollution or significant environmental nuisance, the local authorities may order the owner to reduce such pollution. This is laid down in Section 42 (1) of the Environmental Protection Act, and applies regardless of whether the stove in question is located within a residential area or an industrial area, and whether it belongs to a company or to a private individual.
Information on the use of stoves is available in the leaflet "Før du fyrer løs" ["Before you light up"] from the Danish EPA, and in the leaflet "Korrekt fyring. Sådan udnyttes brændslet bedre" ["How to make the most of your fuel"] from the Danish Ministry of Housing and Urban Affairs. Unfortunately, these leaflets are only available in Danish.
Please note that only unadulterated wood may be used in stoves. This means that stoves may not be used to burn waste such as painted wood, impregnated wood, chipboard, MDF boards, or other types of household waste. Newspapers may, however, be used to light fires.
Please note that orders issued pursuant to Section 42 of the Environmental Protection Act relating to fixed, non-commercial facilities cannot be appealed to any other administrative authority. This is specified in Section 19 of Statutory Order No. 366 of 10 May 1992 on non-commercial animal husbandry, unhygienic conditions, etc.
6.7.3 Input effect of 120 kW or more, but less than 1 MW
Before purchasing new plants of this type, all installations should make sure that they comply with the following emission limit values:
| Dust | = 300 mg/normal m3 dry flue gas at 10 per cent O2. |
| CO | = 500 mg/normal m3 dry flue gas at 10 per cent O2. |
Outlet heights are determined by means of an OML calculation.
6.7.4 Total input effect of 1 MW or more, but less than 50 MW
The following emission limit values apply to these plants:
| Dust | = 40 mg/normal m3 dry flue gas at 10 per cent O2.63 |
| NOX measured as NO2 | = 300 mg/normal m3 dry flue gas at 10 per cent O2.64 |
| CO | = 625 mg/normal m3 dry flue gas at 10 per cent O2. |
If, for example, condensing equipment is used, the emission limit value for dust may be
relaxed to 100 mg/normal m3 dry flue gas at 10 per cent O2.
Outlet heights are determined by means of an OML calculation.
6.7.5 Input effect of 50 MW or more
Plants using wood and with an input effect of 50 MW or more fall within the scope of Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
For older plants, which do not fall within the scope of this Statutory Order, the various emission limits, inspection measures, etc., must be set according to the BAT principle on the basis of a specific assessment, see chapter 1.
Outlet heights are determined by means of an OML calculation.
6.7.6 Inspection
For wood-fired plants with an input effect greater than 1 MW but less than 5 MW, performance inspection should be carried out to verify compliance with the emission limit values.
Wood-fired plants with an input effect of 5 MW or more should be fitted with automatic measuring equipment for measurement and registration of:
 | Dust emissions in accordance with the principle of opacity or methods of a corresponding quality, and |
| CO emissions. |
For wood-fired plants with an input effect of 5-30 MW, compliance with the limit value for NOX should be checked by means of performance inspection.
Wood-fired plants with an input effect of more than 1 MW should be fitted with measurement and regulation equipment for oxygen (O2) to control the burning process. In addition to this, plants with an input effect of more than 30 MW should also be fitted with AMS equipment for NOX.
Wood-fired plants with an input effect of more than 50 MW should be fitted with measuring equipment for CO, dust, NOX, and O2.
For plants with an input effect of 50 MW or more, please see Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
6.8 Straw
6.8.1 General information
The Statutory Order on biomass65 includes more detailed information on which types of straw may be used as a fuel.
Calorific value: 14.5 MJ/kg.
When 1 kg straw is burned, the following approximate quantity of flue gas is formed:
Equations 19 and 20
where % O2 denotes the O2 content in the flue gas, expressed as a percentage by volume. |
6.8.2 Total input effect of 1 MW or more, but less than 50 MW
The following emission limit values apply to these plants:
| Dust | = 40 mg/normal m3 dry flue gas at 10 per cent O2. |
| NOX measured as NO2 | = 300 mg/normal m3 dry flue gas at 10 per cent O2.66 |
| CO | = 625 mg/normal m3 dry flue gas at 10 per cent O2. |
These figures are hourly mean values and must not be exceeded after ten minutes from
firing.
Due to the risk of nuisance caused by smoke, it is recommended that new plants should be 200 m or more from the nearest dwelling.
The outlet height is determined by means of an OML calculation.
6.8.3 Input effect of 50 MW or more
Straw-fired plants with an input effect of 50 MW or more fall within the scope of Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
For older plants, which do not fall within the scope of this Statutory Order, the various emission limits, inspection measures, etc., are set according to the BAT principle on the basis of a specific assessment, see chapter 1.
The outlet height is determined by means of an OML calculation.
6.8.4 Inspection
For straw-fired plants with an input effect greater than 1 MW but less than 5 MW, performance inspection should be carried out to verify compliance with the emission limit values.
Straw-fired plants with an input effect of 5 MW or more should be fitted with automatic measuring equipment for measurement and registration of:
| Dust emissions in accordance with the principle of opacity or methods of a corresponding quality, and |
| CO emissions. |
For straw-fired plants with an input effect of 5-30 MW, compliance with the limit value for NOX should be checked by means of performance inspection.
Straw-fired plants with an input effect of more than 1 MW should be fitted with measurement and regulation equipment for oxygen (O2) to control the combustion process. In addition to this, plants with an input effect of more than 30 MW should also be fitted with AMS equipment for NOX.
Straw-fired plants with an input effect greater than 50 MW should be fitted with measuring equipment for CO, dust, NOX, and O2.
For plants with an input effect of 50 MW or more, refer to Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
6.9 Biomass waste
6.9.1 General information
Statutory Order No. 638 of 3 July 1997 on biomass waste and its Annex provide more detail on the types of biomass waste accepted for use as fuel.
6.9.2 Input effect of 120 kW or more but less than 1 MW
Before purchasing new plants, all installations should make sure that such plants comply with the following emission limit values:
| Dust | = 300 mg/normal m3 dry flue gas at 10 per cent O2. |
| CO | = 500 mg/normal m3 dry flue gas at 10 per cent O2. |
The outlet height is determined by means of an OML calculation.
6.9.3 Total input effect of 1 MW or more, but less than 50 MW
The following emission limit values apply to these plants:
| Dust | = 40 mg/normal m3 dry flue gas at 10 per cent O2. |
| NOX measured as NO2 | = 300 mg/normal m3 dry flue gas at 10 per cent O2.67 |
| CO | = 625 mg/normal m3 dry flue gas at 10 per cent O2. |
The outlet height is determined by means of an OML calculation.
6.9.4 Input effect of 50 MW or more
Plants with an input effect of 50 MW or more fall within the scope of Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
For older plants, which do not fall within the scope of this Statutory Order, the various emission limits, inspection measures, etc., must be set according to the BAT principle on the basis of a specific assessment, see chapter 1.
Outlet heights are determined by means of an OML calculation.
6.9.5 Inspection
For biomass-fired plants with an input effect greater than 1 MW, but less than 5 MW, performance inspection should be carried out to verify compliance with the emission limit values.
Biomass-fired plants with an input effect of 5 MW or more should be fitted with automatic measuring equipment for measurement and registration of:
| Dust emissions in accordance with the principle of opacity or methods of a corresponding quality, and |
| CO emissions. |
For biomass-fired plants with an input effect of 5-30 MW, compliance with the limit value for NOX should be checked by means of performance inspection.
Biomass-fired plants with an input effect of more than 1 MW should be fitted with measurement and regulation equipment for oxygen (O2) to control the combustion process. In addition to this, plants with an input effect of more than 30 MW should also be fitted with AMS equipment for NOX.
Biomass-fired plants with an input effect greater than 50 MW should be fitted with measuring equipment for CO, dust, NOX, and O2.
For plants with an input effect of 50 MW or more, refer to Statutory Order No. 689 of 15 October 1990 on the limitation of emissions of sulphur dioxide, nitrogen oxides and dust from large combustion plants, as amended by Statutory Order No. 518 of 20 June 1995.
6.10 Waste incineration plants
As regards waste incineration plants, a distinction is made between plants burning hazardous waste, and plants that burn household waste, commercial waste, etc.
Plants burning hazardous waste are regulated in Statutory Order No. 660 of 11 August 1997 on the approval, etc., of plants burning hazardous waste.
However, incineration of oil waste, which is also a hazardous waste, does not fall within the scope of Statutory Order No. 660/1997. Instead, such incineration falls within the scope of special provisions, see Appendix 11 in Statutory Order No. 619 of 27 June 2000 on waste. Oil waste may only be incinerated at plants with a thermal output of more than 1 MW. See also section 6.5.
More detailed rules on plants incinerating non-hazardous waste are laid down in Statutory Order No. 41 of 14 January 1997 on waste incineration plants68 and in the Danish EPA Guidelines No. 2/1993 on the limitation of pollution from incineration plants.
Outlet heights are determined by means of an OML calculation.
6.10.1 Inspection
The Statutory Orders specified above feature inspection regulations for the incineration of waste.
6.11 Calorific value, conversion factors, NOX, methods of measurement, etc.
6.11.1 Calorific value
The calorific value is a measure for the amount of heat released upon combustion. A distinction is made between the concepts "lower" and "upper" calorific value. The lower (effective) calorific value describes the quantity of heat which is usually utilised by an energy plant. The upper (calorimetric) calorific value includes the heat that is released from condensation of flue-gas content of steam (water vapour).
The calorific value for each type of fuel is specified under the heading "General information" in each section.
6.11.2 Conversion from ppm to mg/normal m2
| 1 ppm SO2 = 2.93 mg/normal m3 SO2 at 0° C and 101.3 kPa. |
| 1 ppm NO = 1.34 mg/normal m3 NO at 0° C and 101.3 kPa. |
| 1 ppm NO2 = 2.05 mg/normal m3 NO2 at 0° C and 101.3 kPa. |
| 1 ppm CO = 1.25 mg/normal m3 CO at 0° C and 101.3 kPa. |
| 1 ppm CO2 = 1.98 mg/normal m3 CO2 at 0° C and 101.3 kPa. |
6.11.3 NOX
NOX is the name used for the sum of the following nitrogen oxides: nitrogen monoxide (NO) and nitrogen dioxide (NO2).
When determining emissions of NOX, all NOX must be converted into NO2. In practice, emissions of NO and NOX are measured in ppm. The resultant values are totalled, and the sum is converted into mg/normal m3 NO2 by means of the conversion factor for NO2.
See also the example of a conversion from NOX to NO2 in section 3.2.5.2.
When standard fuels are burned, the resultant NOX comprises approximately 10 per cent NO2 and 90 per cent NO.
This does not apply to gas motors69, which generate significantly more NO2.
6.11.4 Measurements and methods of measurement
Measurements should generally be carried out by installations or persons with the appropriate accreditation; see section 5.3.2 for more details. Chapter 8 describes methods of measurement and sample extraction.
| 55 | Statutory Order No. 901 of 31 October 1994. |
| 56 | Statutory Order No. 580 of 22 June 2000 |
| 57 | Natural gas has a bulk density of approximately 0.8 kg/normal m3. |
| 58 | See the example in section 3.2.5.2 on conversion of NOX into NO2 |
| 59 | No. 901 of 31 October 1994. |
| 60 | No. 580 of 22 June 2000. |
| 61 | No. 901 of 31 October 1994. |
| 62 | Statutory Order No. 638 of 3 July 1997 on biomass waste. |
| 63 | As a point of departure, this also applies to condensing wood-fired plants and plants without dust filters. |
| 64 | This only applies to plants with an input effect of 5 MW or more. When firing with wood chips with high bark content and a large proportion of needles, the emission limit value may be raised to 400 mg/normal m3 |
| 65 | Statutory Order No. 638 of 3 July 1997 on biomass waste. |
| 66 | This only applies to plants with an input effect of 5 MW or more. |
| 67 | This only applies to plants with an input effect of 5 MW or more. When firing with wood chips with high bark content and a large proportion of needles, the emission limit value may be raised to 400 mg/normal m3 |
| 68 | See Directive 2000/76/EC on waste incineration. This Directive addresses both hazardous and non-hazardous waste. There will be consultation on a Statutory Order. |
| 69 | For gas motors, please contact the Danish Gas Technology Centre (DGC), Dr.
Neergaards Vej 5A, 2970 Hørsholm. Tel.: (+45) 45 76 60 44. www.dgc.dk. |