Process for recovering energy from a combustible gas

A process for recovering energy from a combustible gas, generated by the partial oxidation of cellulose waste liquor in a gas generator operating in a temperature range of 600.degree.-1500.degree. C. and a pressure in the range of about 1-100 bar, cooling and cleaning said combustible gas by direct contact with an aqueous liquid in a first zone, thereby dissolving inorganic sodium components, forming an alkaline liquor, which liquor is withdrawn from the system for preparation of cooking liquor, discharging said combustible gas from said first zone and passing said combustible gas to fuel a gas turbine plant, thereby contacting at least part of said combustible gas with one of water and steam and burning said combustible gas in the presence of an oxygen containing gas, the improvement comprising the steps of:

• (1) cooling the combustible gas stream leaving said first zone by passing said gas stream to at least one heat exchange zone, where the gas is cooled by heat exchange with at least one coolant to a temperature in the range of 30.degree.-180.degree. C.;
• (2) compressing air to a predetermined pressure;
• (3) bleeding compressed air from the compressed air stream for use as oxidant in the gas generator;
• and
• (4) extracting heat gas from gas turbine exhaust by indirect heat transfer to said combustible gas.