System and method for continuous slag handling with direct cooling

Abstract

A system includes a quench chamber configured to continuously receive a mixture of a gas and slag, and a downstream end portion coupled to the quench chamber. The quench chamber includes a quench sump configured to continuously separate the gas from the slag in the mixture via a quench liquid. The downstream end portion is configured to continuously convey a slag slurry to a depressurization system. The downstream end portion includes a cooling system configured to directly cool the slag slurry with a cooling fluid, and the slag slurry includes the separated slag and at least a portion of the cooling fluid

1 . A system comprising:
 a quench chamber configured to continuously receive a mixture of a gas and slag, wherein the quench chamber comprises a quench sump configured to continuously separate the gas from the slag in the mixture via a quench liquid; and   a downstream end portion coupled to the quench chamber, wherein the downstream end portion is configured to continuously convey a slag slurry to a depressurization system, the downstream end portion comprises a cooling system configured to directly cool the slag slurry with a cooling fluid, and the slag slurry comprises the separated slag and at least a portion of the cooling fluid.   
     
     
         2 . The system of  claim 1 , comprising one or more slag crushers configured to receive the slag slurry. 
     
     
         3 . The system of  claim 2 , wherein the cooling system is disposed at least partially between a first slag crusher of the one or more slag crushers and a second slag crusher of the one or more slag crushers. 
     
     
         4 . The system of  claim 2 , wherein the cooling system is disposed at least partially upstream of the one or more slag crushers. 
     
     
         5 . The system of  claim 1 , comprising a slag crusher coupled to the downstream end portion. 
     
     
         6 . The system of  claim 1 , comprising a reactor coupled to the quench chamber, wherein the reactor is configured to react a carbonaceous feedstock to generate the gas and the slag. 
     
     
         7 . The system of  claim 1 , wherein the cooling system comprises one or more nozzles configured to dispense the cooling fluid directly into the slag slurry. 
     
     
         8 . The system of  claim 1 , wherein the cooling system comprises a plurality of nozzle sets configured to dispense the cooling fluid, wherein each nozzle set comprises one or more nozzles, and each of the one or more nozzles is configured to dispense the cooling fluid at a different angle than another of the one or more nozzles of the respective nozzle set, at a different axial position than another of the one or more nozzles of the respective nozzle set, at a different circumferential position than another of the one or more nozzles of the respective nozzle set, or any combination thereof. 
     
     
         9 . The system of  claim 1 , wherein the cooling system is configured to cool the slag to less than approximately 70 degrees C. 
     
     
         10 . A system comprising:
 a gasifier configured to react a carbonaceous feedstock into a mixture of a gas and slag, wherein the gasifier comprises:
 a quench sump configured to continuously separate the gas from the slag in the mixture via a quench liquid, wherein the quench liquid is configured to flow through the quench sump at a first flow rate; and 
 a downstream end portion of the gasifier comprises a cooling system, wherein the downstream end portion is configured to continuously convey a slag slurry to a depressurization system at a third flow rate approximately 15 percent or less of the first flow rate, the downstream end portion is configured to add a cooling fluid at a second flow rate to cool the slag slurry, and the slag slurry comprises the slag and the cooling fluid; and 
 a controller configured to control the second flow rate. 
   
     
     
         11 . The system of  claim 10 , comprising one or more slag crushers configured to continuously receive the slag slurry. 
     
     
         12 . The system of  claim 10 , comprising the depressurization system coupled to the downstream end portion, wherein the depressurization system comprises one or more orifice plates, one or more let down valves, one or more expansion turbines, one or more centrifugal pumps, or any combination thereof. 
     
     
         13 . The system of  claim 12 , wherein the controller is configured to control the second flow rate based at least in part on a desired flow rate of the depressurization system. 
     
     
         14 . The system of  claim 10 , wherein the cooling system is configured to directly cool the slag slurry to reduce vaporization of the slag slurry upon depressurization in the depressurization system. 
     
     
         15 . The system of  claim 10 , comprising a plurality of sensors configured to provide feedback to the controller, wherein the feedback comprises temperature data, pressure data, flow data, or viscosity data, or any combination thereof. 
     
     
         16 . The system of  claim 10 , wherein the slag comprises less than approximately 5 percent of the quench liquid. 
     
     
         17 . A method, comprising:
 separating slag from a gas, wherein a temperature of the slag is greater than approximately 175 degrees C.;   dispensing a cooling fluid into a downstream end portion of a gasifier, wherein the cooling fluid is configured to decrease the temperature of the slag to less than approximately 70 degrees C.;   forming a cooled slag slurry from the slag and the cooling fluid; and   conveying the cooled slag slurry substantially continuously through an exit of the downstream end portion.   
     
     
         18 . The method of  claim 17 , wherein forming the cooled slag slurry comprises crushing the slag into a plurality of particles with one or more slag crushers. 
     
     
         19 . The method of  claim 18 , wherein the cooling fluid is dispensed upstream, downstream, or between the one or more slag crushers. 
     
     
         20 . The method of  claim 18 , wherein separating the slag from the gas comprises supplying a quench liquid at a first flow rate, wherein the cooling fluid is dispensed at a second flow rate, and the second flow rate is less than approximately 15 percent of the first flow rate.