Method and system for cooling hot gases by water injection

Abstract

Hot gas, produced in a thermal reactor ( 1 ), can be cooled in a cylindrical cooling reactor ( 4 ) by leading the gas tangentially into the evaporative cooler through and inlet duct ( 2 ) whereby the gas perform a rotary movement in the evaporative cooler, and by injection water droplets into the gas at one or more injection zones ( 3 ) in such an amount and in such a way that the gas temperature due to water evaporation is reduced to below 400° C. The dry cooled gas can now leave the reactor through the outlet duct ( 5 ) and be cleaned for particles in a dry filter ( 7 ) and energy can be recovered in a condensing unit ( 8 ). Hereby, a compact cooling, cleaning and energy recovery system is obtained, which is cheap and simple and has low maintenance costs, and which moreover has a high efficiency degree and good environmental qualities. The method can be used for a broad spectrum of fuels and conversion technologies.

1 . A method for cooling hot gases produced in a thermal reactor, said method comprising:
 leading of the hot gas into a cylindrical evaporative cooler with a height/diameter ratio of less than 5 in one or more tangential gas channel inlets with such a velocity that so as to carry out produce a rotary movement in the cylindrical evaporative cooler, and   injecting water in the hot gas at one or more injection zones, in such amount and droplet sizes that the water droplets fully evaporate inside the evaporative cooler.   
     
     
         2 - 10 . (canceled) 
     
     
         11 . The method according to  claim 1 , wherein after injection of water in the hot gas at one or more injection zones in such an amount and droplet sizes that the water droplets fully evaporate inside the cooler and the cooled gas leaves the evaporative cooler through a gas channel placed tangential on the cooler. 
     
     
         12 . The method according to  claim 1 , wherein the injected water is atomised into fine droplets by pressurized water, air, or gas. 
     
     
         13 . The method according to  claim 1 , wherein the cooled gas passes through a condensing heat exchanger unit and at least some of the water vapor is condensed. 
     
     
         14 . The method according to  claim 1 , wherein the water is tap water, process water, or condensate developed elsewhere in the thermal reactor. 
     
     
         15 . The method according to  claim 1 , further comprising removing particles from the bottom of the evaporative cooler. 
     
     
         16 . The method according to  claim 1 , wherein impurities in the cooled gas from the evaporative cooler are removed using a cyclone, a bag house filter, an electrostatic filter or other filter. 
     
     
         17 . The method according to  claim 1 , wherein a chemical agent is injected before, in, or after the evaporative cooler and before the filter so as to improve the cleaning of the gas. 
     
     
         18 . The method according to  claim 1 , wherein the temperature of the gas in an inlet duct is between 300° C.-1500° C. and the outlet temperature of the gas in an exit duct is between 100° C.-400° C. 
     
     
         19 . The method according to  claim 1 , wherein the gas velocity in an inlet or an the outlet exceeds 5 m/s. 
     
     
         20 . A system for cooling hot gases, said system comprising:
 an inlet duct for a hot gas, placed tangentially on a vertical cylindrical evaporative cooler, having at least one water injection device configured to inject water into the hot gas, on top of the evaporative cooler and   an outlet duct.   
     
     
         21 . The system according to  claim 11 , further comprising a means for controlling the water injection into the gas so as to reduce the temperature of the gas to below 400° C. 
     
     
         22 . The system according to  claim 11 , further comprising a gas cleaning unit in the form of a bag filter, electro filter, cyclone, or scrubber. 
     
     
         23 . The system according to  claim 11 , wherein a condensing heat exchanger unit is connected to a gas duct, wherein at least some of the gas contents of water vapor is condensed, and the condensing heat is utilized for heating of a stream of fluid. 
     
     
         24 . The system according to  claim 11 , wherein a water nozzle is placed centrally on the evaporative cooler end cover or on an armature at or after a tangential gas channel inlet. 
     
     
         25 . The system according to  claim 11 , wherein said system is a thermal reactor, which is a gasification reactor, a combustion reactor or part of an industrial process.