THE SOURCE TESTING ASSOCIATION ANNUAL GUIDE 2011


specification. This is typically done by: a an engineering inspection of the bagfilter to confirm that the bagfilter is operating correctly


b by checking the output from the leak instrument to ensure there are no dust peaks on bag cleaning which are out of the ordinary (i.e. different than those associated with other bag rows being cleaned).


This enables the base level of the instrument to be set correctly. Service engineer carrying out filter laek monitor health check


ensures the cost of the calibration is not wasted and the resulting results are valid. The tests performed to ensure an instrument is prepared for correlation testing against isokinetic sampling or configuration is referred to as: n A functionality test for QAL1 and quantitative CEMs n An instrument health check for filter leak monitors and Gross Filter failure detectors


These checks form the fundamental first part of any calibration or configuration procedure


The calibration procedure applied to the particulate monitor depends on the type of monitoring to be performed by the instrument.


1 If the instrument is to be used for EN-14181 reporting (e.g. WID or LCPD plant), quantitative (e.g. Part A or Part B processes) or qualita- tive monitoring (e.g. Part B processes) then the instrument response must be correlated to the results of multiple isokinetic gravimetric samples according to the standard reference method (SRM) which is typically EN-13284-1. n The number of samples taken and the quality of the results defines the type of calibration that is applied to the instrument. n Typically 5 or 3 SRM samples are taken since dust levels from


In both cases the zero of the instrument should be checked since the calibration line or filter leak response curve often uses the zero condition as a calibration point. Since it is often difficult to create zero dust conditions at the time of calibration this is often done by reviewing historical data when the plant is known to be off (nights or weekends) and/or creating a zero condition with a simulated reference material.


Bagfilter after which filter leak monitor is installed


many plant using bagfilters are relatively constant and the SRM results form a calibration cluster


n In instances where dust levels are highly variable, up to 15 calibration points are taken.


n Guidance to the number of samples to be taken for different conditions


is given document RM-QG6.


n Even when instruments are to be set up in indicative mode (i.e. to report mg/m3 as an approximate level) it is good practice to take three samples so that any random errors in sampling are exposed as outliers.


2 If the instrument is to be used as a filter leak monitor then the instrument trend output range and alarm levels are configured once it has been established that the bagfilter is working according to


Type of monitoring


Table 3: Options for continuous monitoring of particulate for part A and B processes Capability of instrument


Tests required on intial set up of instrument


Monitoring to satisfy EN-14181


Quantative measurement


Qualitative measurement


Filter leak monitoring


Indirect monitoring


QAL 1 certified instrument e.g. Class 1 MCERTS


Instrument capable of being calibrated for a specific application e.g. Class 1 or 2 MCERTS


Instrument capable of being calibrated for a specific application e.g. Class 1 or 2 MCERTS


Filter leak monitor with trend output eg Class 3 MCERTS


Parameter with a credible relationship between what is being monitored and a failure condition.


Gross filter failure detection


Instrument designed to detect large increases in emissions


12 Source Testing Association Annual Guide 2011


Instrument functionality test 5/15 point


calibration (see RM-QG-6)


Instrument functionality test 3/5 point calibration (see RM-QG-6)


Set up and 3 point approximate calibration


Set up and set reference Set up


Instrument functionality test 3/5 point calibration (AST) (see RM-QG-6)


Instrument functionality test 3/5 point calibration (see RM-QG-6)


Instrument health check Instrument health check Instrument health check in the Environment Agency’s guidance


Guidance on the calibration procedures for different types of continu- ous monitoring is provided in table 3 below.


Instrument maintenance


Particulate instruments are no different than any other type of electro- mechanical/optical equipment in that they require routine service, especially as they are exposed to the aggressive and dust contaminat- ing conditions of flue gas. It is standard practice (through regulatory requirements and manufacturers’ guidance) for an annual inspection of the instrument to be conducted and this may be more frequent depending on the complexity and operating principles of the instru- ment. Manufacturers of instruments are best consulted for guidance on preventative maintenance requirements to ensure reliable operation from an instrument in a specific application.


Instrument images reproduced with kind permission of Land Instruments International, PCME, Codel International and Durag


Annual tests required 3 yearly tests required


Instrument functionality test 3/5 point calibration (AST) (see RM-QG-6)


Instrument functionality test 3/5 point calibration (see RM-QG-6)


Health check 3 point calibration


Instrument health check Set reference


Health check Set up


What can be recorded from instrument


mg/m3 over time


mg/m3 over time


mg/m3 (approx) over time


Trend of plant operation over time


Trend of plant operation over time


Instrument health check Set up and set alarm


Incidence of gross failure


What functionality enables alarm levels to be set to detect


% of ELV % of ELV Approx % of ELV


Change in plant operation causing a defined factor increase in emissions


Changes in plant operation


Other


performance requirements


95% availability (valid reading at least 95% of time)


95% availability (see above)


95% availability (see above)


95% availability (see above)


95% availability (see above)


Note: eg Water level in wet scrubber or ph in wet scrubber but NOT differential pressure (dp) across a bag filter (dp measures filter blinding but does not change with holes in filters) Set up and set alarm


Catastophic failure of filter


95% availability (see above)


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