Energy recovery
AssigneeImperial Chemical Industries PLC
InventorAlwyn Pinto
Life of this patent
Estimating the term…
Abstract
Energy is recovered from low calorific value gas by means of a gas turbine. Heat is recovered from the turbine exhaust by indirect heat exchange with water. The resultant hot water is used to saturate the fuel and, optionally, also the combustion air, and/or to aid regeneration of an absorbent used in a wet process to remove carbon dioxide from the gas prior to combustion. Preferably the low calorific value gas is waste gas from a PSA process used to remove impurities in the production of a hydrogen-containing gas stream from a raw gas made by primary/secondary steam reforming a hydrocarbon feedstock at superatmospheric pressure and the turbine drives the secondary reformer air compressor.
Claims13
A process for the recovery of energy by the production of shaft power from a fuel gas comprising:
- carbon dioxide;
- and
- at least one combustible gas selected from:
- methane;
- hydrogen;
- and
- carbon monoxide;
- said fuel gas having a composition such that its calorific value is below 1100 BTU/scf (41 MJ.m.sup.-3) and containing at least 20% by volume of carbon dioxide;
- said process comprising:
- (a) contacting said gas with an aqueous solution of an absorbent for carbon dioxide, whereby carbon dioxide is absorbed from said gas into said absorbent solution and the resultant carbon dioxide depleted gas is saturated with water vapor;
- (b) separating the saturated carbon dioxide-depleted gas from said absorbent, so as to give a saturated carbon dioxide depleted gas having a calorific value of 15 to 1100 BTU/scf (0.6 to 41 MJ.m.sup.-3);
- (c) regenerating said absorbent by heating, and returning the regenerated absorbent to step (a);
- (d) compressing air in a compressor;
- (e) combusting said carbon dioxide-depleted gas with said compressed air in a combustion zone;
- (f) expanding the resultant combustion products in an expander driving said compressor and producing the shaft power;
- and
- (g) recovering heat from the turbine exhaust gas by indirect heat exchange and using said recovered heat to heat the absorbent in the regeneration thereof.
Dependencies are inferred from the claim text.