Methods and systems for cooling hot particulates

Abstract

A system for cooling particulates includes a gasifier, a particulate cooler, an elongated shell, a shell side particulate inlet, a tube side fluid inlet, a tube bundle, a coolant outlet, one or more upper aeration nozzles, and one or more lower aeration nozzles. The tube bundle has a plurality of tubulars. The upper aeration nozzles are located within the shell and direct a first aeration gas toward the tube bundle and the lower aeration nozzles are disposed on a sidewall or a narrowing member or the shell and direct a second aeration gas toward a particulate outlet. A related method uses the described system.

What is claimed is: 
     
         1 . A system for cooling particulates, comprising:
 a gasifier in fluid communication with a raw syngas line;   a particulate removal system in fluid communication with the raw syngas line and a particulate line; and
 a particulate cooler in fluid communication with the particulate line, the particulate cooler comprising: 
 elongated shell having a first end, a second end, and one or more sidewalls; 
 a shell side particulate inlet in fluid communication with particulate line and disposed in the one or more sidewalls for receiving particulates; 
 a shell side particulate outlet disposed adjacent the second end for discharging cooled particulates, wherein a narrowing member is situated between the second end and the particulate outlet; 
 a tube side fluid inlet adjacent the first end for receiving a coolant; 
 a tube bundle comprising a plurality of tubulars, wherein the tubulars each have an open first end secured to a first tube sheet and a closed second end, and wherein an inner conduit is concentrically placed within each of the tubulars, the inner conduit having an open first end secured to a second tube sheet and an open second end disposed adjacent to the closed second end; 
   a coolant outlet disposed in the one or more sidewalls between the first tube sheet and the second tube sheet for discharging heated coolant and a coolant inlet disposed adjacent to the first end for receiving coolant;   one or more upper aeration nozzles located within the shell directing a first aeration gas is directed toward the tube bundle; and   one or more lower aeration nozzles disposed on a sidewall of the narrowing member directing a second aeration gas toward the particulate outlet.   
     
     
         2 . The system of  claim 1 , further comprising:
 an aeration gas vent line disposed on the one or more sidewalls at a location between the particulate inlet and the first end of the shell;   a control valve disposed on the aeration gas vent line and coupled to a first pressure sensor disposed on the one or more sidewalls at a height of the aeration gas vent line; and   a second pressure sensor disposed on the one or more sidewalls adjacent the particulate inlet.   
     
     
         3 . The system of  claim 2 , wherein the tube bundle includes: at least one grid guide aligning the tube bundle, at least one guide member supporting the at least one grid guide, and at least one sacrificial bar shielding at least some of the tube bundle from direct contact with the particulates, and wherein the first tube sheet supports the at least one grid guide, the at least one guide member, and the at least one sacrificial bar. 
     
     
         4 . The system of  claim 3 , wherein: at least a proximal end of the tubulars is positioned above the first tube sheet, the first tube sheet is secured to an inner surface of the shell and forms a fluid tight seal with a shell interior and the coolant outlet, and the second tube sheet is secured to the inner surface of the shell and a fluid tight seal with the coolant inlet and the coolant outlet. 
     
     
         5 . The system of  claim 4 , wherein: the at least one guide grid has a plurality of bars and a banding bar connected to an outer edge of each of the plurality of bars, the banding bar forming a circumference around the plurality of bars and maintaining the plurality of bars in a grid pattern. 
     
     
         6 . The system of  claim 1 , further comprising at least one aeration centralizer projecting from the one or more upper aeration nozzles, the at least one aeration centralizer connected to the one or more sidewalls of the shell. 
     
     
         7 . A method for cooling particulates, comprising:
 introducing particulates to a heat exchanger, the heat exchanger comprising:
 a gasifier in fluid communication with a raw syngas line; 
 a particulate removal system in fluid communication with the raw syngas line and a particulate line, and 
 a particulate cooler in fluid communication with the particulate line, the particulate cooler comprising:
 elongated shell having a first end, a second end, and one or more sidewalls; 
 a shell side particulate inlet in fluid communication with particulate line and disposed in the one or more sidewalls for receiving particulates; 
 a shell side particulate outlet disposed adjacent the second end for discharging cooled particulates, wherein a narrowing member is situated between the second end and the particulate outlet; 
 a tube side fluid inlet adjacent the first end for receiving a coolant; 
 a tube bundle comprising a plurality of tubulars, wherein the tubulars each have an open first end secured to a first tube sheet and a closed second end, and wherein an inner conduit is concentrically placed within each of the tubulars, the inner conduit having an open first end secured to a second tube sheet and an open second end disposed adjacent to the closed second end; 
 a coolant outlet disposed in the one or more sidewalls between the first tube sheet and the second tube sheet for discharging heated coolant and a coolant inlet disposed adjacent to the first end for receiving coolant; 
 one or more upper aeration nozzles located within the shell directing a first aeration gas is directed toward the tube bundle; and 
 one or more lower aeration nozzles disposed on a sidewall of the narrowing member directing a second aeration gas toward the particulate outlet; 
 
   flowing the particulates through the shell and contacting at least a portion of the particulates with the tube bundle;   recovering a heated coolant from the coolant outlet; and   recovering cooled particulates from the particulate outlet.   
     
     
         8 . The method of  claim 7 , wherein the particulates comprise fine ash, coarse ash, or a combination thereof. 
     
     
         9 . The method of  claim 7 , wherein the particulates entering the heat exchanger are at temperatures ranging from about 400° C. to about 1,400° C. 
     
     
         10 . The method of  claim 7 , wherein the cooled particulates recovered from the particulate outlet are at temperatures ranging from about 100° C. to about 240° C. 
     
     
         11 . The method of  claim 7 , wherein the particulates have a residence time in the heat exchanger ranging from about 10 s to about 1800 s. 
     
     
         12 . The method of  claim 7 , further comprising:
 forming a dilute phase and a dense phase of the particulates in the shell side of the shell;   selecting a desired height of the dense phase;   determining a pressure differential between the dilute phase and the dense phase; and   adjusting a valve to maintain a desired pressure differential and the desired height of the dense phase.   
     
     
         13 . The method of  claim 12 , wherein the particulate inlet is closer to the closed second end of the tubulars than to the first open end of the tubulars, and wherein the dilute phase occupies at least 30% of an interior height of the shell. 
     
     
         14 . The method of  claim 8 , further comprising venting the first aeration gas via an aeration gas vent line disposed on the one or more sidewalls and above the particulate inlet, wherein the aeration gas vent line comprises a control valve coupled to a first pressure sensor disposed on the one or more sidewalls at the height of the aeration gas vent line and a second pressure sensor disposed on the one or more sidewalls at the height of the particulate inlet. 
     
     
         15 . The method of  claim 14 , wherein a dense fluidized bed of particulates is formed between the second end of the shell and the distal ends of the plurality of tubulars and a dilute bed of particulates is formed between a surface of the dense fluidized bed and the first end of the shell. 
     
     
         16 . The method of  claim 15 , further comprising adjusting a height of the surface of the dense fluidized bed of particulates by controlling a flow rate of the first aeration gas, adjusting a position of the control valve, or a combination thereof.