Patent ID: 6030493
Filing Date: 2000-02-29
Classification: D21C,Y02P

Abstract:
Process for recovering chemicals and energy from spent liquor obtained during paper pulp production comprising:gasifying spent liquor in a first gasification reactor under a first pressure and a first temperature to produce a first smelt and a first combustion gas having a first concentration of process chemicals;dissolving said first smelt in a first aqueous liquid in a first quench vessel to produce a first liquor having a first concentration of process chemicals, wherein said first quench vessel containing a first dip tube connected to said first gasification reactor, said first dip tube opening into said quench vessel above a pool of said first aqueous liquid, whereby contact between said combustion gas and said first aqueous liquid in said pool is substantially avoided;gasifying spent liquor in a second gasification reactor under a second temperature and a second pressure to produce a second smelt and a second combustion gas having a second concentration of process chemicals;dissolving said second smelt in a second aqueous liquid in a second quench vessel to produce a second liquor having a second concentration of process chemicals, wherein at least one of said first temperature or first pressure is selected to be different from said second temperature or second pressure such that at least one of said first concentration of process chemicals in said first combustion gas or said first liquor being different from said second concentration of process chemicals in said second combustion gas or said second liquor;recovering at least one process chemical from said first liquor, said first combustion gas, said second liquor, or said second combustion gas; andsupplying at least a portion of said recovered process chemical to a gasification reactor or quench vessel different from the gasification reactor which originated the process chemical.