Combustion air preheating
AssigneeThe M. W. Kellogg Company
InventorsThomas A. Wells, William C. Petterson
Life of this patent
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Abstract
Combustion air for steam cracking furnaces is preheated by indirect heat exchange with medium pressure and low pressure steam that has been expanded through steam turbines from high pressure steam produced in the hot section of an ethylene production plant.
Claims6
In a process for steam cracking hydrocarbons to cracked gases in a tubular furnace heated by burning a mixture of fuel and combustion air and subsequently quenching the cracked gases wherein waste heat is recovered in the form of high pressure steam and wherein the combustion air is preheated prior to introduction into the furnace, the improvement which comprises:
- (a) superheating the high pressure steam and expanding at least a portion of the superheated high pressure steam through a first turbine to produce shaft work and superheated medium pressure steam at a temperature between 260.degree. and 465.degree. C.;
- (b) expanding at least a portion of the superheated medium pressure steam through a second turbine to produce shaft work and low pressure steam at a temperature between 120.degree. and 325.degree. C.;
- and
- (c) preheating the combustion air by indirect heat exchange with at least a portion of the superheated medium pressure steam and at least a portion of the low pressure steam.
Dependencies are inferred from the claim text.