REFERENCE METHOD European Council of Vinyl Manufacturers

Transcription

1 REFERENCE METHOD European Council of Vinyl Manufacturers Identification, measurement and control of fugitive emissions from process equipment leaks, rev. 2 O/Ref.: Member of the SNC-Lavalin Group

2 TABLE OF CONTENTS 1. DEFINITIONS OBJECTIVES SCOPE OF APPLICATION ECVM PERFORMANCE GUIDELINES APPLICABLE FOR VCM AND EDC Leak Level Definition Leak Rate Measurement Frequency Repair and Maintenance Non-Accessible Equipment METHOD OF ASSESSMENT Principle of the Method Inventory of Sources Targeted Equipment Database Screening Measurements of Process Equipment TYPICAL REPORTS GENERATED Leaking Equipment Report Emission Report REFERENCE DOCUMENTS RESOURCES PERSONS FIGURES Figure 5-1 : P&IDs Review and Points Numbering... 6 Figure 5-2 : Database Elaboration (example using DÉFI Software)... 8 Figure 5-3 : Measurement of VOC Emissions... 9 Figure 5-3 : Application of Response Factor and Correlation Equation APPENDICES Appendix A: Appendix B: Appendix C: Appendix D: Appendix E: Example of a leak report Example of emission reports Implementing a leak detection and repair program Final ECVM correlation curves Response factors and speciation ECVM Reference Method i

3 1. DEFINITIONS Actual concentration True concentration of the chemical compound or mix of chemical compounds around a monitored process equipment Calibration gas The VOC substance used to adjust the instrument meter reading to a known value. The calibration gas is usually the reference compound at predefined concentration ECVM European Council of Vinyl Manufacturers EDC Ethylene dichloride (12-dichloroethane) Fugitive emissions Emissions of volatile organic compounds into the environment resulting from a gradual loss of tightness from process equipment designed to contain an enclosed fluid (gaseous or liquid), basically caused by a difference of pressure and a resulting leak; they are expressed in g per hour per source or in kg per year per site Gas phase Process fluid that is in the gaseous state at operating conditions. Inaccessible equipment Equipment that for purpose of monitoring is more than 2 meters above a permanently accessible support surface or equipment that is unsafe to monitor, which could expose monitoring personnel to imminent hazard from temperature, pressure, at risk concentration or equipment not accessible because cover protected or insulated. LDAR Leak Detection and Repair Program: inspection and maintenance program with the aim to identify, measure and control fugitive emissions by repairing leaking equipment. Leak level (or threshold concentration) Leak rate or leakage percentage Light liquid phase Mass emission rate Monitoring frequency Open ended line (or valve) PVC Reference gas Response factor Screening value above which equipment is identified as a «leaker», and action is to be initiated in order to control the fugitive emission. Percentage of leaking equipment over the total population of similar equipment, which have been measured. Process phase for light liquid substance(s) of which at least 10% weight of the constituent substance(s) have a vapour pressure greater than 0.3 kpa at 20ºC. Mass flow of fugitive emission expressed in g per hour per source. Period of time after which an equipment must be verified for process leak A valve, except safety relief valves, having one side of the valve seat in contact with process fluid and one side open to the atmosphere, either directly or through open piping Polyvinyl chloride. Substance used for the calibration of the monitoring instrument Mathematical ratio of the actual concentration divided by ECVM Reference Method 1

4 Similar equipment the unadjusted screening value. Represent the correction factor to convert a reading obtained with an analyzer calibrated with a reference gas different from the substance or mix of substances being monitored Equipment that can be grouped in the same category for the use of correlation equations, based on similar results of bagging measurements; similar equipment can be further grouped in several families for maintenance and follow up purposes. Speciation The identification of each of the chemical species in a VOC emission Unadjusted screening value Concentration of volatile organic compound measured close around equipment as determined by a monitoring instrument, calibrated with a reference gas, according to a defined protocol. VCM Vinyl chloride monomer. VOC Volatile organic compound, which has at standard conditions at 20 C a vapour pressure of 0.3 kpa or more, as for example EDC and VCM. ECVM Reference Method 2

5 2. OBJECTIVES This reference method is dedicated to give guidance for ECVM plants (VCM/EDC/PVC manufacturing units) in the identification, measurement and control of fugitive emissions from equipment leaks. The main objective is to reduce the fugitive emissions of VOCs and to carry on improvement in all aspects of health, safety and environment at reasonable cost. The second objective is to prepare annual emission reports based on a common reference method. 3. SCOPE OF APPLICATION The reference method and the correlation equations are intended to be used for the quantitative determination of fugitive emission in VCM and PVC process units involved in the ECVM survey (reference 1 and 2) and process units using the same design standards and specifications for equipment and applying the similar maintenance programs. The quantitative assessment is limited to process lines and equipment containing 10 % by volume of VOC or more. A detailed list of targeted categories of similar equipment and exemptions is defined in 5.3. Remark (a) The assessment of fugitive emissions from process units located inside enclosed and ventilated buildings, obtained by multiplying the average concentration measured continuously by a network of chromatographs in several representative points by the flow rate of ventilation is considered by the ECVM as a valid reference method for the purpose of quantification as an alternative to the point screening method described here. (b) The detection of fugitive leaks in the process units in open air trough periodic walkaround by operators equipped with portable detectors close to locations where leaks are likely to occur (valves arrangements, pumps areas, etc.) is also considered by the ECVM as an efficient method to identify and reduce the most significant fugitive emissions to an acceptable level, but not enabling a quantitative assessment nor accurate evaluation of the performances according to the categories of equipment. (c) The classical methods for leak detection already applied during assembly and building of units after maintenance (soap solutions methods, pneumatic testing and hydraulic testing) are also valid to detect the most important leaks, without enabling a quantitative assessment nor an identification of small leaks. In all aforementioned methods, in case of leak detection or increase of measured concentration inside enclosed areas, the qualitative search at points for the immediate identification of the source of the leak and the repair (see 2(d)) are also part of the management for the control of fugitive emissions. ECVM Reference Method 3

6 ECVM considers that those methods are complementary and that their simultaneous implementation justifies a targeted monitoring frequency according to level of performance (see 4(b)). 4. ECVM PERFORMANCE GUIDELINES APPLICABLE FOR VCM AND EDC Note: other performance guidelines could be defined for other VOC, according to their economical value, environmental impact or effect on the health. 4.1 Leak Level Definition A threshold leak level is defined as the detection of a VOC concentration of ppmv or more at the emission source using an appropriate hydrocarbon analyzer according to the measurement protocol of section Leak Rate The leak rate should not be more than 2% for any group of similar equipment monitored inside a process unit. 4.3 Measurement Frequency Monitor all accessible equipment at least one time in order to have a complete inventory of equipment and to assess the leak rate of similar equipment. Define a targeted measurement frequency according to leak rate established in previous monitoring campaigns: - If leak rate < 2 %: monitor similar equipment on a statistical mode in each family, so that each equipment is verified within a defined period of time. - If leak rate > 2 %: monitor on a systematic way all equipment of the family within a defined period of time, for example, 1-3 years. - If leak rate > 5 %: carry out an investigation in order to explain the repeated leaking causes and to reduce them on an appropriate way; document the conclusions. Monitor any equipment after repair. 4.4 Repair and Maintenance The repair of leaks found during monitoring should be completed within short term appropriate time schedule unless a plant shutdown is required or the number of equipment requiring repair is beyond capability of the maintenance resources: in both cases, a record of these exceptions and when they are corrected should be maintained. Equipment that cannot be repaired without a unit shutdown will be identified and the repairs will be planned for the next shutdown. ECVM Reference Method 4

7 4.5 Non-Accessible Equipment The number of non-accessible equipment should be limited (typically < 20 % of similar equipment); an estimate of fugitive emissions from that equipment shall however be included in the annual emission report (see 6.2). 5. METHOD OF ASSESSMENT 5.1 Principle of the Method Fugitive emission losses from process equipment are identified and quantified by following these steps (see appendix C for extended description of the complete procedure): Achieve complete equipment inventory (accessible and inaccessible equipment). Measure accessible equipment by screening as per EPA Method 21 (section 5.5). Report leaks for equipment with a leak leak level threshold. Repair leaks by routine maintenance for leak > leak level threshold; if leak persists, repair again the leak if > ppm. Establish a yearly emission report about fugitive emissions by using the ECVM correlation equations and all (unadjusted) screening values. These equations relate the actual concentrations (obtained by multiplying the unadjusted screening values with the appropriate response factors) to mass emission rates that have been established for European VCM/EDC/PVC plant process equipment. Correlations have been developed for several categories of similar equipment by bagging equipment to measure mass emissions of organic compound. 5.2 Inventory of Sources The approach is to develop the inventory of emission sources. All the points are identified from the list of equipment and process and instrumentation diagrams (P&IDs). All the lines and equipment that are in service with > 10 % VOC at standard temperature and pressure are targeted by the inventory. See Figure 5.1. ECVM Reference Method 5

8 Figure 5-1 : P&IDs Review and Points Numbering 5.3 Targeted Equipment The type of similar equipment which constitutes categories of sources for fugitive emissions and which have to be considered in the inventory count are: Ball valves LL and G Globe valves LL and G Gate valves LL and G Eccentric plug rotary valves LL and G Plug valves LL and G Other valves, like butterfly, plunger, diaphragm valves, etc. Rotating equipment (pump seals, compressor seals, blowers) Pressure relief valves LL and G Equipment and piping flanges and connectors (LL and G) Open ended lines LL and G Sampling connections Valves in service with gas (G) and light liquid (LL) are identified separately because the emission correlation curves are dependent on the volatility. Equipment of all sizes and all diameters should be considered in the inventory since experience has shown that leaks can occur for any equipment size. Equipment that is inaccessible for monitoring must still be included in the database. The software used to manage the data has to estimate all non-monitored equipment using statistical results of monitored equipment during the first inventory by type of equipment and service. ECVM Reference Method 6

9 Exemptions Equipment in vacuum service (internal pressure 95 kpa) for > 90% of the time. Process streams containing > 90 % (volume based) non-organic compounds (i.e. steam, hydrogen, nitrogen, air, etc.). Lines of small diameter for instrument connections can be excluded from a systematic inventory and screening measurement if a low leak rate can be demonstrated by preliminary appropriate checks; it is however recommended to include them in the assessment of the total emission and in reports. Other channeled and diffuse emission sources (i.e. emissions released through stacks or emissions from open sewer, open water surfaces, open equipment, etc) are not covered by this program. 5.4 Database To include inventoried emission sources, a database is developed. The database has to include the following fields (see figure 5.2): Process area Source identification number P&ID number Process type (like PVC-suspension, PVC-emulsion, VCM, EDC) Stream composition in % (ex.: VCM 100 %, VCM: water 90:10 %) Phase (gas, light liquid) Number of hours of operation under positive pressure per year Equipment category (see 5.3) And may include the additional fields: Operating temperature (optional); Operating pressure (optional); Process line number Piping size (optional). Note that the chemical compositions entered in the database for each process line will allow for the determination of the response factors of the process stream. The chemical compositions also allow for the evaluation of total VOC emissions and specific compound emissions for source points associated to a given process stream. The methodologies for the determination of the response factors for a given chemical stream and for the evaluation of the emissions are presented briefly in appendix E. ECVM Reference Method 7

10 Figure 5-2 : Database Elaboration (example using DÉFI 1 Software) 5.5 Screening Measurements of Process Equipment Fugitive emissions of VOC are monitored using Environmental Protection Agency (EPA) Method 21 entitled Determination of Volatile Organic Compound Leaks (see Figures 5.3 and 5.4). IMPORTANT REMARK: EPA Method 21 is intended to identify, locate and assess leaks levels but not to quantify mass emission rates from individual sources. Dedicated ECVM s correlation equations (see Appendix D) are therefore required to link the screening value and the emission rate from an equipment. Measurement routes are established using the equipment and component inventory as per the routing manual. During each measurement period (by shift or by day), the operators carry out the following activities: 01 Calibration of the flame ionization detector (minimum of two, preferably at the beginning and at the middle of the route) and maintenance of the analyzer. 02 Up-loading the measurement route from computer s or any other database. 03 Measurement of the background concentration in each section of the plant in order to subtract this value from the results stored in memory. 04 In situ measurements of the VOC concentrations for each emission point in accordance with the EPA method 21 guidelines. 05 Transfer (by downloading) of the measurement results (unadjusted screening value for each equipment) from the instruments data logger to the database. 06 Print/forward leak report on a regular basis to maintenance personnel to schedule equipment repair. 1 US Patent #6,415,979BI ECVM Reference Method 8

11 Figure 5-3 : Measurement of VOC Emissions VOC leaks are measured using a portable ionization analyzer equipped with a data logger. The analyser s VOC measurement range varies from around 0.5 to ppm in equivalent CH 4, thus allowing the unadjusted screening value to be established and the leaks to be identified. Response factors specific to the analyser are given by the manufacturers to transform the measurements results from equivalent CH 4 to COV. ECVM Reference Method 9

12 Figure 5-4 : Application of Response Factor and Correlation Equation CORRELATION EQUATION Analyser s response factor ppm CH 4 equivalent Correlation equation Emission kg/h Total VOC = (RF X SV) determined by bagging SNC LAVALIN Environment ECVM Reference Method 10

13 Calibration is to be done with the use of span gases at certified concentration. The portable analyser used in Europe must be approved for use in explosible area zones according to CENELEC Gas Group II C, Zone 1 and Zone 2, thus ensuring safe operation in petrochemical environment. 6. TYPICAL REPORTS GENERATED 6.1 Leaking Equipment Report A leak report is given to the maintenance team after each period of measurements. This report contains the information that will enable to retrace the leaks that were found and make the repairs (see Appendix A for an example of leak report generated by computer and dedicated database). 6.2 Emission Report An emission report summarizes the information obtained during the measurement program (see Appendix B for an example of an emission report). The fugitive emission report gives an annual mass emission rate for total VOCs and should be able to provide an annual mass emission rate for all the substances included in the database. The chemical compositions of the process streams must be included in the database to speciate the emissions per chemical. The results are given in kg of chemical emitted by year. The report will include for each category of equipment: Number of sources measured. Mass emission from all equipment measured. Number equipment and equipment with leaks. Estimate of non-accessible equipment. Number of equipment repaired or replaced. Estimate of mass emission for repaired equipment, before and after repair. Proportion of emission from each category of equipment. Estimate of emission from equipment not measured (including non accessible equipment) is made preferably based on mass emissions rate obtained form the first inventory for this category of equipment or either on average unadjusted screening values of the random sampling. These reports can be generated automatically by any software using the ECVM s correlation equations for VCM/EDC/PVC production plants. 7. REFERENCE DOCUMENTS Environmental Code of Practice for the Measurement and Control of Fugitive VOC Emissions from Equipment Leaks, Canadian Council of Ministers of the Environment (CCME), PN 1106, October 1993 ECVM Reference Method 11

14 ECVM-Specific Correlation Equations, Final Report, European Council of Vinyl Manufacturers, September 2004, SNC Lavalin Environment Protocol for Equipment Leak Emissions Estimates, EPA-453/R , US Environmental Protection Agency, 1995 Reference Method 21, Code of Federal Regulations, Title 40, Part 60, Appendix A., Determination of Volatile Organic Compound Leaks. Washington DC. US Government Printing Office, RESOURCES PERSONS Mr. Roger Liégeois Competence Centre for Health, Safety, Environment (CC-HSE) Solvay S.A. rue de Ransbeek 310 B-1120 Brussels Belgium Telephone: Fax: Mr. Jean-Luc Allard SNC-Lavalin Environment Inc. 2271, Fernand-Lafontaine Blvd. Longueuil, Quebec Canada J4G 2R7 Telephone: 1 (450) Fax: 1 (450) jeanluc.allard@snclavalin.com ECVM Reference Method 12

15 Appendix A Example of a Leak Report SITE YYY FUGITIVE EMISSION OF VOC author AAA UNIT PVC-S abc ANNUAL LEAK REPORT date : 01-févr-00 YEAR 1999 approved : BBB date : 10-févr-00 EQUIPMENT INVENTORY LEAK STATUS EMISSION not inspected total inventory inspected without leak with leak leak rate repaired leak leaks to be repaired units n n n n % n n kg/y agitator % flange % open end line % valve % pump % PSV % TOTAL % leak level definition : 1000 not inspected equipment : 8% minimal specified composition % : 10 points included all ECVM Reference Method

16 Appendix B Example of Emission Reports SITE YYY FUGITIVE EMISSION OF VOC author AAA UNIT PVC-S abc ANNUAL EMISSION ESTIMATE date : 01-Feb-00 YEAR 1999 approved : BBB date : 10-Feb-00 EQUIPMENT SCREENING RESULTS EMISSION phase measured estimated average factor reference factor stream factor kg/y n n - - g/h.source g/h.source h/y agitator gas 5 0 0, ,473 0,016 4, flange gas , ,816 0,020 0, light liquid , ,816 0,035 0, open end line light liquid , ,53 0,053 0, valve gas , ,554 0,028 0, light liquid , ,585 0,028 0, pump light liquid , ,47 0,099 4, relief valve gas+ligh liq , ,47 0,187 0, TOTAL leak level definition : 1000 reference to ECVM correlation curves and emission factors minimal specified composition % : 10 proportion of estimated emissions 10,6% points included all average factor : relates to the average of the results obtained from all measurements by screening and corresponding mass emission values derived from correlation equations for each equipment monitored reference factor : relates to the emission factor obtained for that category of equipment during the first inventory (obtained from ECVM survey or from the site first inventory) and applied to equipment which have not been measured (not accessible or not ECVM Reference Method

17 Appendix C Implementing a Leak Detection and Repair Program ECVM Reference Method

18 Implementing a Leak Detection and Repair Program 01 Arrange safety training of personnel that will work on plant site. 02 Organize a visit of the plant site. 03 Collect the information on the plant and process: drawings, Process and Instrument Diagrams (P&ID), Process and Flow Diagrams (PFD), equipment layout, equipment list, process line operation time, etc. 04 Identify, on the drawings, the process lines that will be included in the program. 05 Validate, on-site, the drawings used. Make necessary corrections and updates. 06 Identify, on the drawings, each potential fugitive emission source. 07 List these sources in an appropriate database by giving them a unique identification or tag number. Ideally, the link between the database and an analyzer should be possible. 08 Include, for each point in the database, mandatory information to eventually calculate emissions: type of equipment, phase of process line and hours of operation of the process line. 09 Include for each point in the database other information: P&IDs number, characteristics of the point, description, process line number, composition of the process line, temperature and pressure of the process line, etc. (optional). 10 Choose a method to identify, on site, every point that will be measured (barcodes, pictures, drawings, etc.). 11 Prepare the measurement routes, carefully minimizing time loss. 12 Make necessary acquisition of calibration gases and hydrogen (if using an FID detector) for the analyzer. 13 Calibrate the analyzer each day (see analyzer manual). 14 Upload the measurement route into the portable analyzer. 15 Measure the potential fugitive emission sources using a portable ionization analyzer equipped with a data acquisition instrument. The analyzer should be chosen depending on the types of gases in the process lines. The analyzer should be approved by Cenelec Gas Group II C, Zone 1 and Zone 2, thus ensuring safe operation within petrochemical environment. The analyzer should also allow precise characterization of emission standards. 16 Download the measurements into database. 17 Generate the leak report. Leak reports should be given to the maintenance personnel. ECVM Reference Method

19 18 Repair leaking equipment within a reasonable period. 19 Follow-up on the monitored leaks to confirm repairs as described in Generate annual emission reports after the measurement campaign is over. 21 Analyze the data and decide when the next monitoring round should be performed based on those results (see ECVM performance guidelines). 22 Decide on required or appropriate monitoring frequency of the various families of equipment based on the results of the analysis. ECVM Reference Method

20 Appendix D ECVM Correlation Curves ECVM Reference Method

21 ECVM Correlation Curves for EDC/VCM/PVC Units: Final Edition August 2004 Mass Emission = alpha x (actual concentration) beta For measured (uncorrected) concentration between 1 and ppmv Alpha Beta All flanges 1 LL+G All valves 2 G LL Relief valve LL+G Rotating Equipment LL+G Open end line G + LL including self-contained check valves 2 excluding self-contained check valves and relief valves For a source with a measured (uncorrected) concentration is below 1 ppmv, the previous correlation equations should not be used. The following default zero emission factors should be used instead, by equipment type. Equipment Phase Default zero value (kg/h-source) All valves 1 Light liquid + gas Flanges & check valves Light liquid + gas Open-ended lines Light liquid + gas As valves Rotating equipments Light liquid + gas excluding self-contained check valves and relief valves For a source with a measured (uncorrected) concentration above ppmv, the previous correlation equations should not be used. The following pegged value emission factors should be used instead, by equipment type. Equipment Phase ppmv pegged value (kg/h-source) All valves 1 Light liquid All valves 1 Gas Flanges & check valves Light liquid + gas Open-ended lines Light liquid + gas Rotating equipments Light liquid + gas excluding self-contained check valves and relief valves ECVM Reference Method

22 Appendix E Response factors and chemical speciation ECVM Reference Method

23 Response factors and chemical speciation The response factor is the mathematical ratio of the actual concentration divided by the unadjusted screening value. It represents the correction factor to convert a reading obtained with an analyzer calibrated with a reference gas different from the substance or mix of substances being monitored. It is expressed as follow: Response factor = actual concentration / screening value (unadjusted) Response factors are specific to a model of analyzer and are defined experimentally by the manufacturers for 500 and ppmv of actual concentration. The associated screening values are the unadjusted screening value equivalent to each of the two actual concentration of 500 and ppmv for which the response factors are defined. They are obtained by reversing the equation previously mentioned: Associated unadjusted screening value = actual concentration / Response factor A linear interpolation is performed between the two associated screening values to estimate the response factor at any given (unadjusted) screening value. According to section of the USEPA protocol, no extrapolation can be done to obtain response factors beyond the endpoints. The response factors specified by the manufacturers for the endpoints (500 and ppmv) were used to correct unadjusted screening values outside of the interpolation range. In case of a mixture of substances, the response factors (for both 500 and ppmv) can be calculated for that mixture, according to the method established by the EPA. The equation used is as follow: Re sponse factor mix 1 xi RFi Where xi is the molar fraction of compound i and RFi is the response factor of compound i; specific to the analyzer used. The mass emissions evaluated by the correlation equations are nominally expressed according to the reference gas used for the calibration of the analyzer (ex.: equivalent methane). If chemical-specific response factors are used, this mass emission can therefore be expressed in term of total VOC emissions. The next refinement is the inclusion of the chemical composition of each process stream. The chemical compositions are actually required for the accurate determination of response factors as seen in the equation above. The chemical compositions (percentage of all constituents in a process stream) are then used to perform the breakdown of the total VOC emissions and obtained emissions by chemical. ECVM Reference Method