Guidelines for Air Emission Regulation
5. Terms and inspection rules
5.1 Introduction
In this chapter, section 5.2 describes the various types of terms and how they should be set up. The terms addressed are operating terms, emission terms, and inspection terms.
Three different types of terms require inspection of emissions:
 | Emission terms, where inspection is carried out as performance inspection. |
| Emission terms, where inspection is carried out by means of an Automatic Measurement System (AMS). |
| Emission terms, where inspection is carried out as random testing. |
For the purposes of these Guidelines, "performance inspection" means emission measurement carried out at intervals, e.g. once a year, where 3 samples are taken, each with a duration of one hour (or a different period of time, depending on the measurements or operating circumstances).
"AMS inspection" means continual emission measurement carried out over a relatively long period of time, typically throughout the plant’s life cycle.
"Random tests" means emission measurement carried out at intervals, such as 6 times a year.
Section 5.3 addresses inspection rules for inspection of operation and emissions. Section 5.3.3 describes the scope of emission inspection, both in the main text and in a diagram.
Section 5.4 describes when the emission limit values are complied with.
Section 5.5 shows examples of formulated terms.
This chapter may be used when deciding on terms and when setting inspection rules in an environmental approval or order. It may also be useful with regard to plans to change the terms or inspection provisions laid down in an environmental approval or order.
5.1.1 Definition of self-inspection
Self-inspection is defined as inspection paid for by the installation and either carried out by external laboratories or by in-house staff. This provides installations with the opportunity to take faster action to remedy excessive emissions. Such inspection may be combined successfully with an environmental management system. Measurements carried out by external laboratories should be carried out as accredited measurements. It is recommended that major installations which carry out self-inspection themselves on a regular basis consider applying for accreditation to carry out emission measurement whenever legislation allows for such accreditation.
The Danish EPA advocates inspection of air pollution from installations to be carried out via self-inspection.
5.2 Terms
5.2.1 General issues
Terms in approvals and orders should be clear and unambiguous, and it should be possible to carry out inspections to determine compliance with such terms without expending unreasonable resources.
Terms should be followed up by inspection in order to confirm compliance. The scope of such inspection should be adjusted to reflect the potential environmental impact.
5.2.2 Types of terms
The objective of terms for air pollution is to ensure that such pollution is kept below a specific limit.
These terms may be presented in various ways:
Operating terms
Operating terms are requirements that affect the design and operation of installations and have an impact on air pollution from such installations. Such requirements might involve the maximum capacity of the power plant or the use of specific raw materials.
Emission terms
Emission terms are requirements for air quantities and the concentration of substances emitted by installations, or requirements regarding maximum hourly emissions.
Terms for outlet heights
The objective of terms specifying outlet heights is to ensure compliance with the C-values.
The final part of this chapter features draft terms.
5.2.3 Operating terms
The objective of operating terms is to limit emissions of pollutants, e.g. by ensuring that purification or abatement equipment at installations is always working optimally.
As regards purification or abatement equipment, these terms might entail regular inspection and the setting of acceptable limits for e.g.:
| Visual inspection of bag filters. |
| Measuring flow and pH at scrubbers and wet filters. |
| Operating temperatures in connection with thermal or catalytic combustion. |
| Deposits in cyclones. |
| Leaks and corrosion. |
Such inspection should be followed up, so that all faults are corrected and repaired as soon as the acceptable limits are exceeded.
Naturally, such monitoring requires instruments, indicators, inspection hatches, sampling ports, etc., necessary for inspection. If necessary, the approval must stipulate appropriate terms to ensure that such equipment is available and that all indicators and instrument displays are easily accessible and easy to read. These terms may stipulate that such displays must be situated in a control room or at the operating staff’s usual place of work.
As a rule, purification or abatement plants should not be bypassed50. In some situations, however, purification or abatement plants may be bypassed for technical reasons.
For example,
| bypassing bag filters may be necessary when the flue gas temperature is too low during start-up (below the dew point), or |
| in connection with accidents involving thermal or catalytic combustion plant. |
The bypass period should be as short as possible and must not lead to unacceptable environmental impacts. The terms should state the acceptable extent of such bypass periods and how they should be registered.
Operating terms may be requirements regarding the preparation of an operating log, detailing e.g. the raw materials used, operating temperatures, operating failures and breakdowns, etc. There should also be terms demanding that logs are kept of faults, errors, or accidents on the installation itself (both process and purification or abatement equipment) or during operation.
The operating log and any operation instructions must be available to the supervising authorities upon request. The operating log must be stored at the installation for a specific period of time, for example three years.
5.2.4 Emission and inspection terms
The objective of emission terms is to establish limits for concentrations of the pollution and air quantity emitted. The emission limit value is set:
| as specified in chapter 3, and |
| on the basis of an assessment of the potential performance of an effective and affordable purification or abatement installation of the relevant type. |
Along with terms on maximum air quantities per time unit and outlet height, the emission terms will ensure that concentrations in the surroundings do not exceed the C-value.
As a minimum, emission terms should meet the following requirements:
| They should establish relevant limit values for pollutants. |
| They should establish clear limits and inspection methods. |
| It must be possible to check compliance with such terms without the need for using excessive resources. |
There are three different types of inspection procedures:
Performance inspection
Performance inspection is used at installations with significant pollution (i.e. where the mass flow limit has been exceeded, but where the AMS inspection limit has not).
AMS51 inspection
AMS inspection is used at installations with very significant air pollution (i.e. where the AMS inspection limit has been exceeded), see section 5.3.3.3.
Random testing
Random testing is used at installations with very significant air pollution, where it is not technically or financially feasible to use AMS inspection.
The following issues should always be taken into consideration when setting up emission terms:
| the pollutant (see section 5.2.4.1), |
| the emission limit value (see section 5.2.4.2), |
| the inspection period (see section 5.2.4.3 and section 5.3), |
| the measurement period (see section 5.2.4.4 and section 5.3), |
| the number of individual measurements (see section 5.2.4.5), |
| the operating circumstances during measurement (see section 5.2.4.6), |
| the method of measurement (see section 5.2.4.7), |
| the detection limit (see section 5.2.4.8). |
For AMS inspections, steps should also be taken to ensure:
| that sufficient information on the quality of instruments is available (through tests on sensitivity, zero-point operation, measurement uncertainty, time constant), or that the instrument is approved by the supervisory authority before use, |
| that instruments are installed correctly at the measuring point, |
| that the instrument is serviced and maintained on a regular basis by qualified personnel in accordance with the manufacturer’s recommendations, |
| that the instrument is calibrated regularly, either by the installation itself or by an accredited laboratory, e.g. by means of parallel measurements once a year, |
| that measurement data are stored on a suitable medium and processed for subsequent use by the supervisory authorities. All measurement data should be stored for at least three years, |
| that measurement data are available, in a suitable form, to the operating personnel at their usual workplace via online systems. |
The pollutant may be a chemical substance or a substance group, or pollution may be described in terms of a particular property (such as odour or biological activity).
The term used should state whether there are one or several states (e.g. both gas and particle phase), whether one or more elements are included in calculations for all compounds, etc., and whether the limit values apply, for example, to the sum of specific compounds.
5.2.4.2 The emission limit value
The emission limit value is a limit value for the maximum pollution. This pollution may be stated as mg pollutant/normal m3 from a specific outlet measured at a maximum air flux. The emission limit value must be stated clearly and unambiguously and must include a specific measurement unit and reference condition. For more information on reference conditions, see section 3.1.2.
The inspection period is the period in which emissions are inspected. The length of these inspection periods is usually:
| three hours for performance inspections, |
| one month for AMS inspections, and |
| one year for random tests. |
The inspection period should be sufficiently long to facilitate assessment of a representative part of the emission; i.e. long enough to ensure that random short-term high or low values do not influence the assessment significantly. At the same time, the inspection period should be short enough to make it possible to decide whether the term is complied with within a reasonable period of time.
The measurement period is the period used for each measurement. This applies to both manual and continual measurements. Terms should always include a specification of the measurement period.
Performance inspections normally have a measurement period of one hour or more, depending on what is being measured. If, for example, performance inspection is carried out by means of instruments that register data continuously, the measurement period is usually set at one hour. As a point of departure, performance inspection is carried out once a year, but the intervals between inspections may be longer or shorter, depending on specific assessment of the relevant situation.
For AMS inspections, the shortest theoretical measurement period will depend on the time constant of the instrument used. This time constant is usually less than one minute. In practice, the measurement period is set at one hour, which provides good time for a suitable statistical basis. AMS inspections are carried out on a continuous basis.
Random tests usually have a measurement period of one hour or more, depending on what is being measured. If, for example, random testing is carried out by means of instruments that register data continuously, the measurement period is usually set at one hour. Random tests are carried out regularly each year, but the number of samples taken varies, as specified in section 5.4.3.
It is recommended that the same one-hour measurement period is used for performance, AMS, and random tests alike. Any deviations from this measurement period should be based on special conditions in the process or in the method of measurement that favour a shorter or longer measurement period.
The measurement period may also be set at a period other than one hour if specified in international provisions, such as EU Directives.
5.2.4.5 Number of individual measurements
Inspection terms should state how many individual measurements should be taken. An individual measurement is a quantitative measurement to determine the emission over the measurement period.
Performance inspection is carried out by taking at least three individual measurements, each lasting one hour.
Automatic measuring and registering instruments are used for AMS inspections, and measurement is carried out all the time. If the measurement period is set at one hour, this means that 720 measurements will be carried out during a single month if the installation is operated around the clock. Otherwise the measurements are only carried out when the installation is operating and emissions occur.
Random tests are carried out on six randomly chosen days a year (the installation must be operating on these days). At least two individual measurements must be carried out each day.
Overview of inspection period, measurement period, and number of measurements
Inspection type |
Inspection period |
Measurement period |
Number of individual measurements |
Performance inspection |
E.g. 3 hours |
E.g. 1 hour |
3 per inspection measurement |
AMS inspection |
1 month |
1 hour |
Continuous |
Random testing |
1 year |
E.g. 1 hour |
2 per sample |
In connection with performance inspections, the term should clearly state at what type and level of production measurements should be carried out.
If emissions vary during operation, steps should be taken to ensure that measurements are carried out while emissions are at their maximum level. Emission terms apply to those periods where the installation is operating – i.e. when emissions occur. This means that non-active periods are not included. If the installation is operated for less than one hour at a time, the relevant operating period is used as the averaging time.
The operating circumstances influence the relevant emission limit value.
The inspection terms should state the method of measurement to be used. Chapter 8 features methods of sampling and analysis which may be used when setting up these terms. If the measurements must be accredited, steps should be taken to ensure that accredited laboratories are, in fact, available for the method chosen. The inspection term should be phrased so that it is possible to use other measurement methods of a similar quality, if the installation can justify it.
The detection limit should normally be less than 10% of the emission limit value inspected. If the emission limit value applies to the sum of several substances, measurement results below the detection limit are not included in calculations.
5.2.5 Terms for outlet heights
The objective of the terms for outlet heights is to ensure compliance with the C-values. Outlet heights are calculated by means of the OML model.
At installations with few outlets, the terms will usually require specific outlet heights in order to ensure that the C-value is complied with when the emission limit value is met.
At installations with many outlets, it may be fair to impose terms regarding compliance with C-values as such a procedure will enable the installation to make its own decisions on distribution of outlet heights and purification or abatement, if applicable. Emission limit values must still be set in such cases.
5.3 Type and scope of inspection
Inspections of compliance with terms imposed on plants require inspection terms that specify when it can be said that a given term is complied with or exceeded.
Three different types of inspection are used:
| inspections of operation, see section 5.3.1, |
| inspections of emissions, see sections 5.3.2 and 5.4, |
| inspections of outlet heights, see section 5.4.4. |
Inspections of operation are carried out by monitoring the relevant process or plant. Inspections of emissions are carried out by measuring or calculating the relevant emission.
5.3.1 Inspections of operation
The installation must carry out inspections of operation by monitoring the relevant processes and plants in accordance with the terms set. The operating terms are deemed to be complied with when the operating log has been correctly kept and the terms set up for the operation observed.
5.3.2 Inspection of emissions
Inspection of emissions may be carried out by measuring – if necessary by calculating – the relevant emission. All measurements must be carried out in accordance with the relevant emission terms.
Who carries out inspection of emissions?
| The installation may let an accredited laboratory carry out performance inspections or random tests. |
| The installation may carry out performance inspections, AMS measurements or random tests itself. |
| The emission may be calculated by means of mass balances, production data, or similar data. |
Large-scale installations carrying out self-inspection on a regular basis should consider applying for accreditation to carry out emission measurements if current legislation allows for this. Measurements should be carried out as specified in chapter 8.
5.3.3 Type and scope of inspection of emissions
Figure 5
shows the scope of inspection of emissions.
The use of the various types of terms depends on the significance of the emissions. The installations are divided into the following categories:
5.3.3.1 Installations with less significant air pollution
Installations with less significant air pollution are installations where the mass flow (substance quantities prior to purification or abatement) is less than the mass flow limit. In such cases, emission measurements are usually not required, and inspection can be limited to an effective inspection of operation. However, emission measurements may also be required in order to document that the mass flow remains below the mass flow limit, as well as to determine the maximum hourly emission where this cannot be done by means of calculations.
5.3.3.2 Installations with significant air pollution
Installations with significant air pollution are installations where the mass flow (substance quantities prior to purification or abatement) exceeds the mass flow limit, but remains below the AMS inspection limit specified in section 5.3.3.3.
When issuing approvals to such installations, requirements should be made that inspections of compliance with the operating provisions that are significant to limiting air pollution should be carried out daily, or even more regularly. This must also apply to inspections to verify that all significant measures designed to limit pollution function correctly. There should also be requirements stipulating that emission measurements, usually in the form of performance inspection, must be carried out once a year if an emission limit has been specified. However, if the result of a performance inspection shows a value of less than 60 per cent of the emission limit value, such measurements need only be carried out every second year.
Performance inspection for dioxins and furans should be carried out for all outlets with a mass flow (substance quantity prior to purification or abatement) greater than 0.1 mg dioxins and furan/hr, measured as mg I-TEQ.
At normal operating circumstances, at least two (parallel or serial) individual samples must be taken for dioxin analysis twice a year for new installations and once a year hereafter, if the emission limit value is complied with. If the emission complies with the relevant requirements over a period of two years, measurements may be carried out at even greater intervals. The measurement period for individual samples must be 6-8 hours in order to ensure a sufficiently low detection limit.
5.3.3.3 Installations with very significant air pollution
Installations with very significant air pollution are defined as installations where the mass flow (substance quantities prior to purification or abatement) for each outlet exceeds the AMS inspection limits, as specified below. AMS for measurement of the relevant emissions should be mandatory for such installations.
5.3.3.3.1 AMS inspection limits for gaseous substances
Any outlet (individual outlet) with a mass flow (substance quantity prior to purification or abatement) greater than
| 200 kg/hrSO2, |
| 25 kg/hr organic substances, measured as TOC, |
| 200 kg/hrNOX, measured as NO2, |
| 2 kg/hr group 1 substance, |
should be fitted with AMS for measurement of the relevant substances.
5.3.3.3.2 AMS inspection limits for particles, etc.
Any outlet (individual outlet) with a mass flow (substance quantity prior to purification or abatement) greater than 2 kg/hr of the substances specified below52 should be fitted with AMS for measurement of the installation’s emissions of:
| group 1 substances, |
| lead and lead compounds, measured as lead, |
| copper and copper compounds, measured as copper, |
| mercury and mercury compounds, measured as mercury, |
| tellurium and tellurium compounds, measured as tellurium, |
| thallium and thallium compounds, measured as thallium, |
| vanadium and vanadium compounds, measured as vanadium. |
Any outlet (individual outlet) with a mass flow (substance quantity prior to purification or abatement) greater than 200 kg particles/hr (other than those specified above) should be fitted with AMS for measurement of the installation’s particle emissions.
Random tests are used in situations where use of AMS is impossible.
5.4 When are the terms complied with?
What follows are descriptions of when terms are complied with. Such information should be included directly in terms in approvals and orders, as this will help avoid problems regarding the burden of proof in any subsequent legal action.
5.4.1 Performance inspection
The emission terms are complied with when the arithmetical average value of all individual measurements carried out during the performance inspection is less than or equal to the required value.
5.4.2 AMS inspection
The emission terms are complied with when the arithmetical average value of all individual measurements carried out during the inspection period (one calendar month) is less than or equal to the required value.
5.4.2.1 Inspection rules for individual measurements
If an individual measurement exceeds the emission limit value by a factor of three or more, the supervisory authority must be notified. At the same time, an account must be given of the reason behind this breach and of the measures taken, or about to be taken, in order to prevent future problems. In addition to this, intensified monitoring of the equipment designed to limit pollution must be carried out. This must be done in consultation with the supervising authority.
5.4.3 Random testing
In random testing, a number of samples are taken at intervals during the inspection period. In principle, these samples must be taken on six randomly selected operating days during a single year. A single sample comprises two individual measurements, each lasting one hour. The result of such a sample is the average value of these two measurements.
5.4.3.1 Inspection rule for random testing
The assessment of whether the required value is complied with is carried out in accordance with the following principles:
| K is the required value, |
| M1 is the inspection-limit value for the emission measured, |
| M2 is the inspection-limit value for the number of samples, |
| M is the average value of all samples taken during the inspection period, and |
| N is the number of samples taken. |
On this basis, it is possible to establish the following two rules for whether the required value is complied with, and whether the number of samples taken is adequate:
The limit value (K) is complied with if M (the measured value) is less than the inspection limit value for the emission measured. The inspection limit value (M1) is calculated as follows:
Equation 7
M1 = K x 37 where q (the geometric dispersion) is calculated as follows:
Mi is the result of the individual samples. |
5.4.3.3 The random sample rule
The number of samples taken is sufficiently large if M is less than the inspection limit value for the number of samples (M2), which is calculated as follows:
Equation 8
M2 = 2 x K x 19-q |
If this is not the case, the number of samples taken during the next inspection period must be increased by three.
The terms of both rules must be met in order to comply with the required value.
If the terms of the rule on limit values are not met, but the sample rule is complied with, the limit value is considered exceeded.
If neither the limit value rule nor the sample rule are met, the number of samples taken during the next inspection period should be increased, and measures should be taken to reduce emissions of the relevant parameter.
If the limit value rule is met, while the sample rule is not, this should lead to an increase in the number of samples taken during the next inspection period as well as increased inspection (inspection of operation) of the equipment designed to limit pollution.
If the results of at least two inspection periods show that the emissions measured amount to less than 50 per cent of the required values, the number of samples taken per inspection period may be reduced from six to four. If this pattern is repeated, the number of samples taken may be reduced further, from four to two, and finally to a single annual performance inspection. If the required value is exceeded, the number of samples to be taken each year will return to six.
5.4.3.4 Inspection rules for individual measurements
If an individual measurement exceeds the emission limit value by a factor of three or more, the supervisory authority must be notified. At the same time, an account must be given of the reason behind this breach and of the measures taken, or about to be taken, in order to prevent future problems. In addition to this, intensified monitoring of the equipment designed to limit pollution must be carried out. This must be done in consultation with the supervising authority.
Example of the application of this inspection rule
Terms: The emission of cadmium from the installation outlet, measured as an annual mean value determined by means of random testing, must not exceed 100 µg/normal m³. Data:
Exponent:
q = 0.077 Inspection limits: M1 = 100 x 370.077 = 132.1 µg/normal m³ M2 = 2 x 100 x 190-0.077 = 159 µg/normal m³ Mean value: M = A/N = 792/6 = 132 µg/normal m³ Conclusion: M less than M1? Yes, 132 is less than 132.1: the emission
is approved. |
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5.4.4 Inspection of outlet height
The authority may request documentation for the height of the outlet.
5.4.5 Inspection of absolute filters
Absolute filters should always be checked for leaks after installation and repairs.
Absolute filters should not be inspected during normal operation. Inspections are carried out on demand, and must always be carried out when the filter has been removed, adjusted, or repaired. The filter must always, however, be inspected at least once a year.
The most widely used test method is a leak test (e.g. ASME N510 and DS/EN
1822/4 and 5). The leak should not exceed 0.03 per cent for particles with a size of 0.3 mm.
The separation efficiency of 99.97 per cent for 0.3 m m particles is tested by the manufacturer after production. For example, such a test may be carried out in accordance with DS/EN 1822/1-3.
5.5 Examples of terms
5.5.1 Example A. Installation with less significant air pollution
An installation uses paint that contains toluene. The surface treatment process used at this installation leads to the following emission of toluene: Toluene is emitted from outlet A, and the installation states that the mass flow of toluene over a single shift is approximately 2,000 g/hr. The air quantity in the outlet is estimated at approximately 4,000 normal m³/hr on the basis of information about the ventilation system. This means that the emission concentration, without purification or abatement, is approximately 500 mg/normal m³.
According to chapter 3, the mass flow limit for toluene is 6,250 g/hr.
As the mass flow is below the mass flow limit, the installation does not have to carry out any purification or abatement, and inspection can be carried out on the basis of operating terms.
The outlet height is determined on the basis of the maximum emission concentration of toluene over an hour. This value has been set at 1,000 mg/normal m³ on the basis of the consumption pattern for toluene during a single shift and the C-value for toluene, which is set at 0.4 mg/m³.
As the dispersion coefficient is 2,775 m³/s and this figure is greater than 250 m³/s, the installation has carried out an OML calculation to determine that the outlet must be at least 10 m above ground level.
Terms for air pollution from the installation and the inspection hereof are as follows:
Outlet height and operating terms
|
5.5.2 Example B. Installation with significant air pollution
An iron foundry emits sand dust from two outlets due to sand mixing and knocking-out castings: outlet 1(sand mixing) emits an air quantity of 40,000 normal m3/hr, and outlet 2 (knocking out) emits an air quantity of 17,000 normal m3/hr.
The emission concentration of the air prior to purification or abatement in the two outlets is between 300 and 1,000 mg dust/normal m3.
Calculations show that the total mass flow of the installation from the two outlets is approximately 50 kg/hr on average over 7 hours.
The dust in the outlets is considered to be total dust, i.e. dust that contains particles larger and smaller than 10 µm.
The dust belongs under table 9 of these Guidelines, "Other dust", with a mass flow limit of 5 kg/hr and an emission limit value of 10 mg/normal m3.
As the installation’s mass flow of sand is greater than the mass flow limit for other dust (5 kg/hr), and as the emission concentration in the two outlets for other dust is greater than the emission limit value for other dust, purification or abatement is necessary. This may be carried out by means of bag filters, etc.
The AMS inspection limit for dust is 200 kg/hr.
As the AMS inspection limit for dust has not been exceeded, there is no need to use AMS.
The terms for air pollution from the installation and inspection hereof are as follows:
Outlet No. |
Pollutant |
Air quantity
normal m3/hr |
Emission limit value
mg/normal m3 |
Outlet height, metres |
No. 1 |
Sand dust |
40,000 |
10 |
X |
No. 2 |
17,000 |
10 |
Y |
The emission limit values apply to both outlets (1 and 2).
Outlet No. 1 must be at least X m above ground level.
Outlet No. 2 must be at least Y m above ground level.
The sampling points in the outlets must be designed in accordance with guidelines in chapter 8 of the Danish EPA Guidelines for Air Emission Regulation. Documentation hereof must be submitted to the approving authority.
Inspection
Operating instructions for the filters must be available in the immediate vicinity of the filters. Operation and inspection of the bag filters must be carried out in accordance with the manufacturer’s operating instructions. A weekly log must be kept of the inspection of filters to check that the bag filters are not worn out. Any operating disruptions, breakdowns, and other relevant information must be recorded in the log, stating the date, year, and possibly time.
The log must be available for inspection by the supervising authority and must be stored at the installation for at least three years.
Not later than three months after the receipt of this approval, the installation must carry out an accredited performance inspection of outlets 1 and 2 in order to document compliance with the emission limit value. Each performance measurement must include at least three individual measurements, each lasting approximately one hour. This measurement must include measurement of the relevant air quantity.
When this has been completed, performance measurements must be carried out at least once a year. However, if the result of a performance measurement is less than 60 per cent of the emission limit value, such measurements need only be carried out every second year.
The following method of measurement53 must be used:
Substance |
Method of measurement |
Dust |
VDI 2066/7 |
Deviations from this method of measurement must be duly justified and approved by the approving authority.
Inspection rules for performance inspection
The emission limit value is complied with when the arithmetic average of the three (or the relevant number) measurements carried out during the inspection period is less than or equal to the limit value. The inspection period is the total measurement period.
Operating terms must also be set.
5.5.3 Example C. Installation with very significant air pollution
An installation manufactures a number of organic coarse chemicals and organic intermediates for other chemical industries. These products are used as raw materials and intermediates by manufacturers in the pharmaceuticals sector.
Sulphur dioxide (SO2) is emitted through the installation outlet P. The installation states that the mass flow of sulphur dioxide is approximately 300 kg/hr, and that the air quantity in the outlet is approximately 1,000 normal m³ /hr. The concentration prior to purification or abatement is approximately 300 g/normal m³.
According to chapter 3 of these Guidelines, the mass flow limit for SO2 is 5,000 g/hr. The emission limit value for SO2 is 400 mg/normal m³.
According to section 5.3.3.3, the AMS inspection limit for SO2 is 200 kg/hr.
As the installation’s mass flow of SO2 is greater than the mass flow limit for SO2, and as the emission of SO2 is greater than the emission limit value, purification or abatement must be carried out in order to ensure compliance with the emission limit value for SO2.
As the installation’s mass flow of SO2 is greater than the AMS inspection limit, the emissions must be inspected by means of AMS.
The outlet height has been determined by means of an OML calculation on the basis of the relevant limit value for emissions and the maximum air quantity, and has been set at Z m above ground level.
The terms for air pollution from the installation and the inspection hereof are as follows:
Emission limit value applying to outlet P:
Parameter |
Emission limit value |
Outlet height, calculated using metres |
SO2 |
400 |
Z |
| The discharges from outlet P must be at least Z m above ground level. |
| The air quantity in outlet P must never exceed 1,200 normal m³/hr. |
| The purification or abatement plant must always be operating during production. |
Inspection
Instruments and software (methods of analysis) intended for use in AMS measurements for SO2 must be approved by the supervisory authority before use. The instruments must be installed correctly at the point of measurement, and must be serviced and maintained regularly by qualified staff in accordance with the manufacturer’s directions. The procedures for operation and maintenance of equipment must be available in a manual.
The air quantity must be checked when the plant is established.
The operating instructions must be available in the immediate vicinity of the equipment.
The measurement instruments must be calibrated in accordance with the manufacturer’s directions. In addition to this, parallel measurements must be carried out in the form of performance inspection. The first of these measurements must be carried out no later than two months after the installation begins operation, and once every year after that. These inspections must be carried out by an accredited laboratory.
The following method of measurement must be used54:
Substance |
Method of measurement for AMS |
SO2 |
DS/ISO 7935 |
Deviations from this method of measurement must be duly justified and approved by the approving authority.
The sampling points in the outlets must be designed in accordance with the guidelines featured in chapter 8.
All measurement data from the AMS measurements in outlet P must be continually displayed on-screen and recorded. It must also be possible to have hourly and daily values displayed on-screen. All measurement data must be stored for at least three years and must be presented to the supervising authority upon request.
Inspection rules for AMS measurements
The emission limit value is complied with when the arithmetic average of all one-hour measurements taken during the inspection period is less than or equal to the limit value. The inspection period is one calendar month. Periods without any emission of the relevant substance must not be included in the inspection period.
If a single one-hour measurement exceeds the emission limit value by a factor of 3 or more, the supervising authority must be notified. At the same time, an account must be given of the reason behind this breach and of the measures taken, or about to be taken, in order to prevent future problems. In addition to this, intensified monitoring of the equipment designed to limit pollution must be carried out. This must be done in consultation with the supervising authority.
Furthermore, operating terms must be set.
| 50 | "Bypass" means that the polluted air is led around the purification or abatement installation. |
| 51 | The letters AMS form an acronym for Automatic Measuring System. An AMS system uses fixed measuring equipment to measure and record emissions. A CEN standard establishing performance requirements for AMS systems is currently being prepared. See also section 5.3.3.3. |
| 52 | Both in particle form and gaseous form |
| 53 | This method is recommended in the list of methods in chapter 8. |
| 54 | See the list of methods in chapter 8. |