Scrubber bypass system

• US 4,245,569 A
• Filed: 03/26/1979
• Issued: 01/20/1981
• Est. Priority Date: 03/26/1979
• Status: Expired due to Term

• Current Assignee: Combustion Engineering Incorporated (ABB Limited)
• Original Assignee: Combustion Engineering Incorporated (ABB Limited)
• Inventors: Fallon, George W. III
• Primary Examiner(s): Favors, Edward G.
• Application Number:
  US06/023,872
• Time in Patent Office: 666 Days
• Field of Search: 110/203, 110/215, 110/163, 110/162, 110/344, 110/345, 432/72, 432/66, 266/146, 266/159
• US Class Current: 110/215
• CPC Class Codes: F23J 15/04 using washing fluids scrubbers for removing solids only F23J15/022

Abstract

A scrubber bypass damper comprises a plate pivotally-mounted to a shaft running across the bypass duct transverse to gas flow. The damper plate self-actuates and rotates about the shaft in response to any pressure differential established across it. A scrubber booster fan is disposed in the main flue at a location downstream of the scrubber and upstream of the outlet of the scrubber bypass into the main flue. When the scrubber is in operation, the pressure rise imparted to the flue gas by the scrubber booster fan is adjusted to keep the damper plate disposed transverse to gas flow through the bypass duct thereby preventing gas flow therethrough. When the scrubber is taken out-of-service, the booster fan is shutdown and the damper plate self-actuates, opening in response to pressure forces exerted on it by the induced draft fan, thus preventing over-pressurization of the furnace.

Claims

1. In an apparatus having a furnace, a stack for venting combustion products formed in said furnace to the atmosphere, a main flue for conveying the combustion products away from the furnace to the stack, a first fan disposed in said main flue between the furnace and the stack, a scrubber for removing pollutants from the combustion products, the scrubber disposed in said main flue between said first fan and the stack, and means located in said main flue at the inlet of the scrubber for controlling the flow of the combustion products through the scrubber;

a scrubber bypass system comprising;

a. a second fan disposed in said main flue between the scrubber and said stack;

b. means operatively associated with said second fan for modulating the pressure rise imparted to the combustion products by said second fan;

c. a bypass duct having an inlet opening into said main flue at a location between said first fan and said means for controlling the flow of the combustion products through the scrubber and an outlet opening into said main flue at a location between said second fan and the stack, said bypass duct thereby providing a flow path for passing the combustion products around the scrubber; and

d. means disposed in said bypass duct for controlling the flow of combustion products through said bypass duct, said means being self-actuating in response to the pressure differential between the static pressure of the combustion products in said main flue at the inlet of said bypass duct and the static pressure of the combustion products in said main flue of the outlet of said bypass duct.

2. An apparatus as recited in claim 1 wherein said means disposed in said bypass duct for controlling the flow of combustion products through said bypass duct provides an essentially gas-tight barrier across said bypass duct when the static pressure of the combustion products in said main flue at the outlet of said bypass duct is equal to the static pressure of the combustion products in said main flue at the inlet of said bypass duct.

3. An apparatus as recited in claim 2 wherein:

a. said bypass duct has a horizontally orientated run therein; and

b. said means for controlling the flow of combustion products through said bypass duct comprises;

a shaft transversely disposed across the roof of the horizontally orientated span of said bypass duct, said shaft being free to rotate about its axis; and

a plate mounted to and suspended from said shaft, said plate suitably adapted to provide an essentially gas-tight barrier when disposed vertically downward across said bypass duct.

4. An apparatus as recited in claim 3 further comprising means operatively associated with said shaft for indicating the angular displacement from vertical of said plate.

5. An apparatus as recited in claim 2 wherein:

a. said bypass duct has a vertically orientated run therein; and

b. said means for controlling the flow of combustion products through said bypass duct comprises;

a shaft horizontally disposed across the vertically orientated span of said bypass duct so as to define in a horizontal plate through said shaft a first and a second flow area on opposite sides of said shaft, said shaft being free to rotate about its axis; and

a counterweighted plate mounted to said shaft, said plate suitably adapted to provide an essentially gas-tight barrier when disposed horizontally across said bypass duct.

6. An apparatus as recited in claim 5 further comprising means operatively associated with said shaft for indicating the angular displacement from horizontal of said counterweighted plate.