Steam boilers
AssigneeFoster Wheeler Energy Corporation
InventorsRobert L. J. Hayden, Alan Bell
Life of this patent
Estimating the term…
Abstract
There is always a danger of slagging on and/or corrosion of the tubes of the highest temperature superheater bank and, if present, reheater bank when burning heavy bunker fuel oil. Therefore a clean fuel burning furnace is provided which is separate from the heavy bunker fuel oil burning furnace and only the combustion gases from burning the clean fuel are used to heat the highest temperature superheater bank and, if present, reheater bank. The clean fuel is preferably provided by a gasifier in which a portion of the heavy bunker fuel oil is pre-combusted to give a clean combustible fuel gas.
Claims10
A steam boiler comprising:
- a heavy oil burning furnace,
- a separate clean fuel burning furnace,
- a first pass through which combustion gases from said heavy oil burning furnace travel,
- a second pass through which combustion gases from said clean fuel burning furnace travel, and
- a superheater tube bank, chosen from a single superheater tube bank and a finishing or highest temperature superheater tube bank, positioned in said second pass and swept by combustion gases from said clean fuel burning furnace.
A steam boiler comprising:
- a heavy oil burning furnace,
- a separate clean fuel burning furnace,
- a common flue,
- a first pass through which combustion gases from said heavy oil burning furnace travel to said flue,
- a second pass through which combusion gases from said clean fuel burning furnace travel to said flue,
- a superheater tube bank chosen from a single superheater tube bank and a finishing or highest temperature superheater tube bank, positioned in said second pass,
- a reheater tube bank, chosen from a single reheater tube bank and a finishing or highest temperature reheater tube bank, positioned in said second pass following said superheater tube bank and also swept by combustion gases from said clean fuel burning furnace, and
- heating elements optionally including at least one lower temperature superheater tube bank and at least one lower temperature reheater tube bank positioned in said first pass and swept by combustion gases from said heavy oil burning furnace.
A steam boiler comprising:
- a heavy oil burning furnace,
- a separate clean fuel burning furnace,
- a common flue,
- a gas pass for combustion products from said clean fuel burning furnace leading to said common flue,
- a high temperature superheater tube bank in said gas pass,
- a high temperature reheater tube bank following said high temperature superheater tube bank in said gas pass,
- a pair of parallel gas passes for combustion products from said heavy oil burning furnace, at least one lower temperature superheater tube bank positioned in one of said parallel gas passes,
- at least one lower temperature reheater tube bank positioned in one of said pair of parallel gas passes,
- an economiser tube bank positioned in one of said pair of parallel gas passes,
- communication ports between said passes at intermediate positions along their lengths, and
- means for supplying a flow of cooling air over each reheater tube bank when there is no steam flow through the reheater tubes, all of the combustion gases and the cooling air then being directed to flow over said economiser tube bank.
Dependencies are inferred from the claim text.