High intensity ionization-electrostatic precipitation system for particle removal and method of operation

Claim 2

In a method for removing fine particles from a feed stream in which the particles in the feed gas stream are charged in a single high intensity ionization step and the charged particles are thereafter collected in a downstream plate-wire electrode type electrostatic precipitation step: the improvement comprising first passing the fine particle--containing feed gas stream through an upstream plate-wire electrode type electrostatic precipitation step prior to said charging at the same gas velocity as the downstream electrostatic precipitation step with the upstream particle collection area A I in said upstream plate-wire electrode type electrostatic precipitation step and the downstream particle collection area A D in said downstream plate-wire electrode type electrostatic precipitation step and X the fraction of the arithmetic sum A T of A I and A D which is represented by A I , all in accordance with the following formulas: A.sub.I =A.sub.T times X where A I =the upstream particle collection area A T =the arithmetic sum of upstream plus downstream particle collection areas A I and A D X=K(1-2/C) 1 .35 C=-1n (1-η o ) η o =the nominal operating efficiency of the upstream and downstream plate-wire electrode type electrostatic precipitation absent the high intensity ionization and being between 0.95 and 0.98, and K=between 0.92η o 11 and (8.21-7.34 η o )/η o 7 .5.

Claim 3

A method according to claim 1 in which the upstream particle collection area A I is between 0.25 and 0.41 of the total particle collection area A T .

Claim 4

A method according to claim 2 in which the particles are fly ash, the nominal operating efficiency η o of the upstream and downstream precipitators is 0.95, and the upstream particle collection area A I is 0.29 of the total particle collection area A T .

Claim 5

A method according to claim 3 in which the particles are fly ash, the nominal operating efficiency η o of the upstream and downstream precipitations is 0.98, and the upstream particle collection area is 0.39 of the total particle collection area A T .

Claim 6

A method according to claim 2 in which the particles are fly ash, the nominal operating efficiency η o of the upstream and downstream precipitators is 0.96, and the upstream particle collection area is 0.31 of the total particle collection area A T .

Claim 7

Method according to claim 1 in which the particles are fly ash and the nominal operating efficiency η o of the upstream and downstream electrostatic precipitation is between 0.965 and 0.98.

Claim 8

Apparatus for removing fine particles from a gas stream comprising: (a) a first upstream electrostatic precipitator of parallelly spaced plates having an upstream particle collection area A I , a multiplicity of wires equally spaced between each pair of adjacent plates and positioned at intervals in the longitudinal flow direction from a gas inlet end to a gas discharge end and oriented with the wire length nominal to the direction of gas flow, and means for establishing an electric field between such first upstream plates and wires; (b) a high intensity ionizer in flow communication with the gas discharge end of said first electrostatic precipitator (a) comprising a multiplicity of tubular Venturi means as anodes each aligned with the throat section thereof adjacent the first electrostatic precipitator. A disc-shaped member as a cathode positioned within each tubular Venturi means, and means for establishing a high intensity electric field between each of said tubular Venturi means and said disc-shaped member; (c) at least a second downstream electrostatic precipitator in flow communication with the gas discharge end of said high intensity ionizer (b) having substantially the same flow cross-sectional area as said first electrostatic precipitator comprising parallelly spaced plates having a downstream particle collection area A D , a multiplicity of wires equally spaced between each pair of adjacent plates in parallel alignment to each other and positioned at intervals in the longitudinal flow direction from a gas inlet end to a gas discharge end and oriented with the wire length normal to the direction of gas flow, and means for establishing an electric field between such second downstream plates and wires; with (d) the upstream particle collector area A I , the downstream particle collection area A D being constructed and the high intensity ionizer being positioned with X the fraction of the arithmetic sum A T of A I and A D which is represented by A I , all in accordance with the following formulas: A.sub.I =A.sub.T times X where A I =the upstream particle collection area A T =the arithmetric sum of upstream plus downstream particle collection areas A I and A D X=K(1-2/C) 1 .35 C=-ln(1=η o ) η o =the nominal operating efficiency of the upstream and downstream type electrostatic precipitators (a) and (c) absent the high intensity ionizer (b) and between 0.95 and 0.98, and K=between 0.92 η o 11 and (8.21-7.34 η o )/η o 7 .5 (e) housing means for enclosing said upstream electrostatic precipitator array (a), said high intensity ionizer (b), and said downstream electrostatic precipitator (c).

Claim 9

Apparatus for removing fine particles from a gas stream comprising: (a) a first upstream electrostatic precipitator of parallelly spaced plates having an upstream particle collection area A I , a multiplicity of wires equally spaced between each pair of adjacent plates and positioned at intervals in the longitudinal flow direction from a gas inlet end to a gas discharge end and oriented with the wire length nominal to the direction of gas flow, and means for establishing an electric field between such first upstream plates and wires; (b) a high intensity ionizer in flow communication with the gas discharge end of said first electrostatic precipitator (a) comprising a multiplicity of tubular Venturi means as anodes each aligned with the throat section thereof adjacent the first electrostatic precipitator. A disc-shaped member as a cathode positioned within each tubular Venturi means, and means for establishing a high intensity electric field between each of said tubular Venturi means and said disc-shaped member; (c) at least a second downstream electrostatic precipitator in flow communication with the gas discharge end of said high intensity ionizer (b) having substantially the same flow cross-sectional area as said first electrostatic precipitator comprising parallelly spaced plates having a downstream particle collection area A D , a multiplicity of wires equally spaced between each pair of adjacent plates in parallel alignment to each other and positioned at intervals in the longitudinal flow direction from a gas inlet end to a gas discharge end and oriented with the wire length normal to the direction of gas flow, and means for establishing an electric field between such second downstream plates and wires; with (d) the upstream particle collector area A I , the downstream particle collection area A D being constructed and the high intensity ionizer being positioned with X the fraction of the arithmetic sum A T of A I and A D which is represented by A I , all in accordance with the following formulas: A.sub.I =A.sub.T times X where A I =the upstream particle collection area A T =the arithmetric sum of upstream plus downstream particle collection areas A I and A D X=K(1-2/C) 1 .35 C=-ln(1=η o ) η o =the nominal operating efficiency of the upstream and downstream type electrostatic precipitators (a) and (c) absent the high intensity ionizer (b) and between 0.95 and 0.98, and K=between 0.92 η o 11 and (8.21-7.34 η o )/η o 7 .5 (e) housing means for enclosing said upstream electrostatic precipitator array (a), said high intensity ionizer (b), and said downstream electrostatic precipitator (c).

Claim 10

Apparatus according to claim 7 in which the upstream particle collection area A I is between 0.25 and 0.41 of the total particle collection area A T .