Method and apparatus for shielding cooling tubes in a radiant syngas cooler

Abstract

Methods and a system for shielding cooling tubes in a radiant syngas cooler. The heat shields may prevent direct contact between heated syngas and the cooling tubes. The heat shield may be mounted to a header that also attaches to the cooling tubes. The heat shield may also be separated from the cooling tubes or, alternatively, the heat shield may be coated onto the cooling tubes. Furthermore, prolonged exposure to the heated syngas may corrode the heat shield.

1 . A system, comprising:
 a syngas cooler heat shield sized to shield one or more cooling tubes in a syngas cooler from direct exposure to a heated flow of syngas from a gasifier.   
     
     
         2 . The system of  claim 1 , comprising the one or more cooling tubes, wherein the syngas cooler heat shield resists temperatures up to at least approximately 2000° Fahrenheit for a first time of at least greater than approximately one minute, and 2800° Fahrenheit for a second time of at least greater than approximately one hour. 
     
     
         3 . The system of  claim 1 , comprising the one or more cooling tubes, wherein the syngas cooler heat shield extends from an upstream end portion of the cooling tubes in a downstream direction of the heated flow. 
     
     
         4 . The system of  claim 1 , comprising the one or more cooling tubes, wherein the syngas cooler heat shield is coated directly onto the one or more cooling tubes. 
     
     
         5 . The system of  claim 1 , comprising the one or more cooling tubes, wherein the syngas cooler heat shield has a limited lifetime based at least partially on a corrosion rate when exposed to the heated flow from the gasifier, and the syngas cooler heat shield is configured to be replaced or supplemented by deposits onto the cooling tubes as a result of operation of the radiant syngas cooler. 
     
     
         6 . The system of  claim 1 , comprising the one or more cooling tubes, wherein the syngas cooler heat shield is disposed between the heated flow of syngas passing through an inner circumference of the syngas cooler heat shield and the cooling tubes disposed about an outer circumference of the syngas cooler heat shield. 
     
     
         7 . The system of  claim 1 , wherein the heat shield has a limited lifetime based at least partially on a corrosion rate, and the heat shield is configured to corrode by heat, sulfur, or chlorides, or any combination thereof. 
     
     
         8 . The system of  claim 1 , wherein the heat shield is sized at a thickness that decreases in a downstream direction in the gasifier. 
     
     
         9 . A system, comprising:
 a gasification cooling system comprising:   a heat exchanger comprising a coolant circuit and a gas passage, wherein the gas passage comprises an inlet, an outlet, and an expanded portion between the inlet and the outlet in an axial direction of the heat exchanger, and the coolant circuit comprises coolant tubes disposed along the gas passage between the inlet and the outlet; and   a syngas cooler heat shield extending partially along a length of the coolant tubes, wherein the syngas cooler heat shield is sized to shield the cooling tubes from direct exposure to a heated flow of syngas from a gasifier.   
     
     
         10 . The system of  claim 9 , wherein the syngas cooler heat shield comprises a protective coating directly on the coolant tubes. 
     
     
         11 . The system of  claim 10 , wherein the protective coating comprises a ceramic material or a ceramic matrix composite material. 
     
     
         12 . The system of  claim 10 , wherein the protective coating has a thickness that decreases in a downstream direction from the inlet toward the outlet. 
     
     
         13 . The system of  claim 9 , wherein the syngas cooler heat shield comprises an annular sleeve separate from the tubes. 
     
     
         14 . The system of  claim 13 , comprising a header coupled to the coolant tubes, wherein the header is disposed in the gas passage between the inlet and the expanded portion in a radial direction of the heat exchanger; 
     
     
         15 . The system of  claim 14 , wherein the annular sleeve hangs from the header between the inlet and the expanded portion. 
     
     
         16 . The system of  claim 15 , wherein the annular sleeve comprises a ceramic, a ceramic matrix composite, a metal, a cermet, or a combination thereof. 
     
     
         17 . The system of  claim 9 , wherein the syngas cooler heat shield has a limited lifetime based at least partially on a corrosion rate, and the heat shield is configured to corrode by heat, sulfur, or chlorides, or any combination thereof. 
     
     
         18 . A system, comprising:
 coolant tubes configured to be disposed along a gas passage of a heat exchanger; and   a syngas cooler heat shield extending partially along a length of the coolant tubes, wherein the heat shield is sized to shield the cooling tubes from direct exposure to a heated flow of syngas from a gasifier.   
     
     
         19 . The system of  claim 18 , wherein the syngas cooler heat shield is coated directly onto the one or more cooling tubes at a thickness that decreases along the length of the coolant tubes. 
     
     
         20 . The system of  claim 18 , wherein the syngas cooler heat shield has a limited lifetime based at least partially on a corrosion rate, wherein the syngas cooler heat shield is configured to be replaced or supplemented by deposits onto the cooling tubes as a result of operation of gasifier, wherein the heat shield is configured to corrode by heat, sulfur, or chlorides, or any combination thereof.