CHALLENGE
 SPM levels of all the Units were much higher than the standard norms.
 Degradation in the performance of ESP’...
CAUSE & EFFECT
MATERIAL
MACHINE
METHODSMEN
High Ash
High resistivity
Distribution screen
Electrode alignment
PF Coal/Ash g...
ALTERNATIVES CONSIDERED
a. Continue to run with present ESPs with ammonia dosing:
This option was investigated but was not...
CONCEPT OF HYBRID ESP’s
 ESP-FF hybrid precipitator is a combination of ESP & Fabric filter
 It has an advantage of both...
HYBRID ESP- THE PROJECT
 VAL-CPP has undergone Bag filter modification in a phased manner
 Last two fields of ESP were r...
HYBRID ESP- THE PROJECT
 Project Zero date – Nov-2011
 Manpower involved in each unit is around 300
 123 m3 of concrete...
HYBRID ESP- AFTER COMMISSIONING
 Fabric filter system is fitted with high temperature bags -
Polyphenylenesulphide (PPS) ...
HYBRID ESP- PERFORMANCE
 Reductions in SPM < 40 mg/Nm3
 Improvement in collection efficiency and stable operation of ESP...
HYBRID ESP - PERFORMANCE
127
111
99 92
81
71 66
55
47 41 45
24 22 20 23 25 26 28 24 26
0
40
80
120
160
200
Nov-11 Dec-11 J...
HYBRID ESP – ASH REMOVAL SYSTEM
 Fiber filter always adopts differential pressure control mode for cleaning
the ash
 Dif...
HYBRID ESP – OPERATION
 Amount of moist, acid and sticky dust collected on the filter bags during
the start-up phase to b...
HYBRID ESP – MAINTENANCE
 Regular checking of differential pressure of dust collector.
 Monitoring of gas flow.
 Checki...
THANK YOU
Hybrid ESP Project
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Hybrid ESP Project

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Hybrid ESP Project

  1. 1. CHALLENGE  SPM levels of all the Units were much higher than the standard norms.  Degradation in the performance of ESP’s.  Chances of enforcement of norms of emissions less than 50 mg/Nm3.  Characteristics of coal and ash not consistent with the design.  Requirement of frequent maintenance of ESP’s.  Reduction in the collection efficiency of ESP’s. HIGH EMISSIONS
  2. 2. CAUSE & EFFECT MATERIAL MACHINE METHODSMEN High Ash High resistivity Distribution screen Electrode alignment PF Coal/Ash grain size Ash Evacuation Control of O2 Uniform coal feeding Conveying air flow/pressure Rapping cyclesTemp monitoring ESP Controllers Slurry disposal/SILO level control Maintenance practices Ash evacuation cycle timing Size of Fields SPM around 100 mg/Nm3 High flue gas volume Transformer sizing High SCC
  3. 3. ALTERNATIVES CONSIDERED a. Continue to run with present ESPs with ammonia dosing: This option was investigated but was not viable due to PCB standards, which may be even reduced in near future. b. Going for dual conditioning system Ammonia & SO3 to reduce emission below 50 mg/Nm3. This option was investigated and evaluated, and trials were taken with the test kit for ammonia dosing. This option was financially not viable. c. Retrofit the ESP and install a fabric filter plant with high temperature bags: After comparing this option with the other options and evaluating the economic benefits of each, it was found that this was both economically and strategically, the most feasible option
  4. 4. CONCEPT OF HYBRID ESP’s  ESP-FF hybrid precipitator is a combination of ESP & Fabric filter  It has an advantage of both ESP & Fabric filter  Gases are separated from dispersed particles by passing it through fabric medium  Particles that are not able to penetrate will remain on the surface of medium so called “Filter cake”  90% dust collection is done by ESP fields rest by bag filters
  5. 5. HYBRID ESP- THE PROJECT  VAL-CPP has undergone Bag filter modification in a phased manner  Last two fields of ESP were removed and bag filter was installed  Modification completed for all the 9 units.  EPC contractor – SEPCO
  6. 6. HYBRID ESP- THE PROJECT  Project Zero date – Nov-2011  Manpower involved in each unit is around 300  123 m3 of concrete is installed  454 tones of steel erection  Timely completion of the project as per schedule.
  7. 7. HYBRID ESP- AFTER COMMISSIONING  Fabric filter system is fitted with high temperature bags - Polyphenylenesulphide (PPS) were considered taking the worst scenario  Low temperature bags - Polyacrylonitrile (PAN) may also be used  The performance of the plant is good with emission values consistently below the 50mg/Nm3 Filter Plant Type : Pulse Jet Filtration Velocity : 1.04 m/min Bag Material : PPS (PTFE Impregnation Treatment) Bag Quantity : 5002 Bag Specification : Dia 130 X 8065 Injection Pressure : 0.25 -0.35 MPa
  8. 8. HYBRID ESP- PERFORMANCE  Reductions in SPM < 40 mg/Nm3  Improvement in collection efficiency and stable operation of ESP’s.  Reduction in energy consumption of ESP’s.  Increase in life of bag filters due to small pressure difference across filter bags.  Maintenance friendly.  OPTIPOW pulse valve adopted to guarantee high efficiency and for. stable and reliable ash removal  The operation of the equipment is controlled by PLC through the temperature, pressure differential pressure, current, voltage and the travel feedback signal
  9. 9. HYBRID ESP - PERFORMANCE 127 111 99 92 81 71 66 55 47 41 45 24 22 20 23 25 26 28 24 26 0 40 80 120 160 200 Nov-11 Dec-11 Jan-12 Feb-12 Mar-12 Apr-12 May-12 Jun-12 Jul-12 Aug-12 Sep-12 Oct-12 Nov-12 Dec-12 Jan-13 Feb-13 Mar-13 Apr-13 May-13 Jun-13 Average SPM Average SPM Before After
  10. 10. HYBRID ESP – ASH REMOVAL SYSTEM  Fiber filter always adopts differential pressure control mode for cleaning the ash  Differential pressure of dust collector is the enhancer of ash removal from bag filters  Ash removal will not stop until differential pressure of bag filter drops below the set value when the differential pressure of the dust collector surpasses a setting value, PLC will transmit a signal to the pulse controller, then the pulse valve will open, the compressed air in the air tank will instantly release and enter into the filter bag. The dust cake accumulated on the outside will break and get loose and then drop into dust hopper when the filter bag expands
  11. 11. HYBRID ESP – OPERATION  Amount of moist, acid and sticky dust collected on the filter bags during the start-up phase to be minimized  The FF shall not be connected to the flue gas stream until coal starts to be fired in the boiler and the thermal power achieves 80% above the total thermal power  The flue gas temperature ought to be at least 20℃ above the acid dew point Main monitoring Screen
  12. 12. HYBRID ESP – MAINTENANCE  Regular checking of differential pressure of dust collector.  Monitoring of gas flow.  Checking the compressed air of pulse cleaning dust collector  Checking nozzle compartments and dust hopper for dust accumulations  When about 10% of the bags in a compartment have been blocked, all damaged bags shall be replaced
  13. 13. THANK YOU
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