what are the types of metals and alloys needed for the construction of the different parts?
See https://en.wikipedia.org/wiki/Electrostatic_precipitator and perhaps find one or more manufacturers on line who might share this information, some of which may be proprietary.
https://en.wikipedia.org/wiki/Electrostatic_precipitator
Dear Nishtha
In case of dry and non-corrosive the ESP material of construction is carbon steel, it is depends upon Temperature gas composition wet or dry.
Most ESPs are constructed of carbon steel having Carbon 0.3 to 0.6 %.
When the stream is highly corrosive, more corrosion resistant materials such as stainless steel the composition as following
SS 304
Cr-18-20%, Ni-10-10%,Mn-2.0 %, Si-1.0%, C-0.08,
SS 304L
Cr-18-20%, Ni-8-12%, Mn-2.0%,. Si-1.0%, C-0.03%
The outer sheet or casing wall is usually made of low-carbon or mild-grade steel
CONTAINS CARBON 0.3 TO 0.6%
The wires are usually made from high-carbon steel
CONTAINS 0.6% TO 1.7% CARBON
The plates are generally made of carbon steel. However, plates are occasionally made of stainless steel or alloy steel for special flue-gas stream conditions where corrosion of carbon steel plates would occur.
Regards
Prem Baboo
This technology is getting replaced now by bag filters. Bag filters are much better from separation efficiency and operation cost. The only disadvantage of it is the limited operating temperature < 220 oC.
Dear Nishtha,
I am assuming that you are talking about dry ESP's. The comments above are correct. I have had to replace the internals of a unit after it overheated (>550degC).
For wet ESP's (WESP's) the situation is generally different. Here the intent is to remove fume in the range of 0.2 microns diameter. Frequently it is acid gas and any condensate will be acidic. In this case there are a number of options. Generally the WESP comprises tubes with central electrodes. The electrodes are of a high quality alloy such as Hastelloy and frequently they are rigid rods rather than ropes. The are also normally made to have high points to aid with the electrical discharge. The tubes are more frequently plastic or composite though I am old enough to have worked on a unit built out of lead! A tiny water spray is introduced to the gas stream. It gets ionised and is pulled to the wall forming a film. It is the film that provides the conductivity on the plastic wall.
Ibrahim,
Bagfilters have issues all of their own. If you are prepared to spend the money up front on a modern dry ESP, you can install two, three or even four ionising stages getting dust limits down to the 15mg/Nm3 range. And, you can do it at temperature. Bags are great at low temperature but are an ongoing maintenance expense.
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