Method and Apparatus for Waste Heat Recovery and Emission Reduction
AssigneePreferred Utilities Manufacturing Corporation
InventorsDaniel P Wallace, Jianhui Hong, Charles A White, III, David G Bohn
Life of this patent
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Abstract
The current invention discloses a method and apparatus for production of hot water or steam in a 4-pass firetube boiler. A waste heat stream is passed through the first and second passes of the boiler, and then routed into a furnace tube (which is the third pass of the boiler) to help suppress the flame temperature and NOx emissions from the burner. The flue gas from the third pass is then passed through the fourth pass of the boiler to transfer the heat energy to the water in the boiler.
Claims19
A method of producing hot water or steam in a four-pass firetube boiler, comprising the steps of,
- a) producing a waste heat stream in a combustion process separate and independent of said boiler;
- b) passing a first portion of said waste heat stream through a first and second passes of firetubes of said boiler to recovery heat energy;
- c) supplying a fuel and a combustion air stream to a burner to produce a flame in a furnace tube of said boiler, said furnace tube forming the third pass of said boiler;
- d) routing said first portion of said waste heat stream to said burner to reduce flame temperature and NOx emissions from said flame;
- e) producing a flue gas from said flame in said furnace tube;
- f) passing said flue gas through a fourth pass of said boiler, wherein said fourth pass comprises a plurality of firetubes;
- g) routing said flue gas to the exhaust outlet of said boiler.
An apparatus for producing hot water or steam, said apparatus comprising
- 1) a 4-pass firetube boiler comprising
- 1a) a shell substantially cylindrical in shape, having a front end and a back end;
- 1b) a front tube sheet and at least one back tube sheet;
- 1c) a furnace tube and a plurality of firetubes positioned inside the shell and substantially extending the length of the shell from the front end to the back end, said furnace tube forms a third pass, said firetubes form a first and second passes and a fourth pass in said boiler, wherein said first pass comprises a firetube and allows a first portion of a waste heat stream to flow in the direction from the front end to the back end;
- said second pass comprises a plurality of firetubes and allows said first portion of said waste heat stream to flow in the direction from the back end to the front end;
- said third pass allows a flue gas to be produced within and to flow in the direction from the front end to the back end;
- and said fourth pass comprises a plurality of firetubes and allows said flue gas to flow in the direction from the back end to the front end;
- 1d) water in a lower part of a void space defined within the boundaries of said shell, said front and back tube sheets, said furnace tube and firetubes up to a desired water level, leaving an upper part of said void space for collecting water vapor or steam.
- 2) a burner affixed to the front end of said boiler producing a flame in said furnace tube, comprising a. a supply of fuel with means of flow control and safety shutoff;
- b. a supply of combustion air with means of flow control;
- c. means for ignition;
- d. means for detecting the presence of said flame;
- wherein said first portion of said waste heat stream passes through said first and second passes of said boiler to transfer heat energy to the water in said boiler, and is then routed to said burner to reduce temperature of said flame and to reduce NOx emissions from said flue gas.
Dependencies are inferred from the claim text.