What are the types of:
• The structural design and operation of the discharge electrodes (rigid-frame, wires or plate)
• collection electrodes (tubular or plate)
• The method of charging (single-stage or two-stage)
• The temperature of operation (cold-side or hot-side)
• The method of particle removal from collection surfaces (wet or dry) ?
The answer is provided point wise as per the question:
1.The emitting electrodes are stainless steel spiral wires of 2 to 3 mm diameter subjected to 35 to 70 KV DC voltage suspended across the flue gas path about 13 metre high.
2. The collecting electrodes are plate type and grounded of same height as the discharge electrodes.
3. Single stage charging through a PLC system for charging and rapping mechanism to dislodge collected fly ash from the collecting plates at regular interval.
4.Operating range 130 to 150 degree Celsius.
5.Collected in dry state from ESP hoppers but latter out side the ESP the ash is mixed with water to finally discharge in a flow able slurry form.
Thanks R.S.Muduli.
Bhubaneswar/INDIA. Ex.AGM/NTPC Limited
The answer is provided point wise as per the question:
1.The emitting electrodes are stainless steel spiral wires of 2 to 3 mm diameter subjected to 35 to 70 KV DC voltage suspended across the flue gas path about 13 metre high.
2. The collecting electrodes are plate type and grounded of same height as the discharge electrodes.
3. Single stage charging through a PLC system for charging and rapping mechanism to dislodge collected fly ash from the collecting plates at regular interval.
4.Operating range 130 to 150 degree Celsius.
5.Collected in dry state from ESP hoppers but latter out side the ESP the ash is mixed with water to finally discharge in a flow able slurry form.
Thanks R.S.Muduli.
Bhubaneswar/INDIA. Ex.AGM/NTPC Limited
Radhashyam provided you a good answer. I try to expand it.
All kinds of discharge electrodes have been tried and AFAIK in large thermal power plants practically only different types of wires are used
In small scale tubular has been used, but AFAIK in large thermal power plants practically only plate types is used
Charging is much trickier question as the higher charge you can maintain the higher is the collection efficiency. All manufacturers have their own software that optimizes charging.
In large thermal power plants the operating temperature is 100 - 250 oC. One can build hot ESPs that operate around 400 - 450 oC the main problem is cost and materials. Higher than that one would need to start cooling which would really add cost. One can easily build and operate ESP at cold state, but in large thermal power plants you would have acidic dew point and then water dew point causing corrosion.
Most current ESPs have some corrosion problems.
Practically all ESPs in large thermal power plants have dry surfaces. Wet works, but there is evaporation.
Industrial precipitators are housed in large size closed space where the dust particles are ionised and attracted to a positively charged technically earthed collecting plates. The plates are intermittently tapped through rapping hammers for continuous dust precipitation on collecting plates. Fly ash from flue gas are separated in coal fired thermal power plants in this type of ESP.
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