Jacketed firetube system for a process vessel

Abstract

A jacketed firetube system for use in a process vessel such as a heater or heater/treater has a jacket which extends along the firetube, at a flame inlet end. The jacket can be external to the firetube or internal to the firetube. A heat transfer fluid is circulated along the firetube between the jacket and the firetube for recovering heat from the firetube and reducing the firetube's temperature. The recovered heat is reintroduced into the system.

1 . A method for recovering heat from a firetube immersed in a process fluid in a process vessel, for heating the process fluid, the method comprising:
 circulating a cool heat transfer fluid in a circulation circuit in thermal communication with and extending along at least a portion of the firetube and therewith, for recovering heat from the firetube for heating the heat transfer fluid therein; and thereafter   transferring the heat from the heated, heat transfer fluid to the process fluid.   
     
     
         2 . The method of  claim 1  comprising:
 circulating the cool heat transfer fluid along at least a portion of an external surface of the firetube for recovering heat from the firetube for heating the heat transfer fluid. 
 
     
     
         3 . The method of  claim 1  comprising:
 circulating the cool heat transfer fluid along at least a portion of an internal surface of the firetube for recovering heat from a flame therein for heating the heat transfer fluid and the at least a portion of the internal surface of the firetube. 
 
     
     
         4 . The method of  claim 1  further comprising:
 regulating the circulation of the heat transfer fluid in response to the temperature in the firetube. 
 
     
     
         5 . The method of  claim 1  wherein the heat transfer fluid compatible with the process fluid; and further comprising:
 mixing the heated, compatible heat exchange fluid with the process fluid in the vessel for recovering the heat therefrom. 
 
     
     
         6 . The method of  claim 5  comprising:
 introducing the heated, compatible heat exchange fluid to a feed stream of process fluid for mixing with the process fluid in the vessel. 
 
     
     
         7 . The method of  claim 5  wherein the compatible heat transfer fluid is a product fluid produced by the process vessel, the method further comprising:
 flowing a slipstream of the product fluid from the process vessel through the circulation circuit. 
 
     
     
         8 . The method of  claim 5  wherein the compatible heat transfer fluid is a product fluid produced by the process vessel, the method further comprising:
 flowing a slipstream of the product fluid from the process vessel through the circulation circuit; and 
 introducing the heated, product fluid from the circulation circuit to a feed stream of process fluid for mixing with the process fluid in the vessel. 
 
     
     
         9 . The method of  claim 1  wherein the heat transfer fluid is a product fluid produced by the process vessel, the method further comprising:
 flowing a slipstream of the product fluid from the process vessel through the circulation circuit; and 
 introducing the heated, product fluid from the circulation circuit to a feed stream of process fluid for mixing with the process fluid in the vessel. 
 
     
     
         10 . The method of  claim 1  wherein the heat transfer fluid is incompatible with the process fluid, further comprising:
 flowing the heated, incompatible heat transfer fluid to a heat exchanger for recovering heat therefrom; and 
 transferring the heat recovered by the heat exchanger to the process fluid in the vessel. 
 
     
     
         11 . The method of  claim 10  further comprising:
 flowing a feed stream of process fluid through the heat exchanger for transferring the heat to the process fluid in the vessel. 
 
     
     
         12 . The method of  claim 10  wherein the incompatible heat transfer fluid is glycol. 
     
     
         13 . A jacketed firetube system for transferring heat from a firetube to a process fluid in a process vessel, the firetube adapted for connection to a burner at a first burner end and a vent stack at a second outlet end and having a passageway therebetween for directing hot gases from the burner to the vent stack, the firetube being immersed in the process fluid, the system comprising:
 a circulation circuit extending along at least a portion of the firetube for circulating a heat transfer fluid therein, the circulation circuit comprising:
 a tubular jacket, extending along the firetube from the first burner end along at least a portion thereof, the jacket in thermal communication therewith and defining a circulation space therebetween; 
 an inlet to the jacket for delivering cool, heat transfer fluid to the circulation space; and 
 an outlet from the jacket for discharging heated, heat transfer fluid therefrom, 
   wherein the heat transfer fluid is circulated through the circulation space for recovering at least a portion of the heat from the firetube.   
     
     
         14 . The jacketed firetube system of  claim 13 , wherein the jacket is external to the at least a portion of the firetube. 
     
     
         15 . The jacketed firetube system of  claim 13 , wherein the jacket is internal to the at least a portion of the firetube. 
     
     
         16 . The jacketed firetube system of  claim 13  wherein the tubular jacket extends along the at least a portion of the firetube that has a surface temperature detrimental to the process fluid. 
     
     
         17 . The jacketed firetube system of  claim 13  wherein the heat transfer fluid is compatible with the process fluid, the system further comprising:
 a fluid connection between the jacket outlet and the process vessel for flowing the heated, heat transfer fluid discharged from the jacket outlet for mixing with the process fluid in the vessel for recovering the heat therefrom. 
 
     
     
         18 . The jacketed firetube system of  claim 17  wherein the heat transfer fluid compatible with the process fluid is the vessel's product fluid. 
     
     
         19 . The jacketed firetube system of  claim 18  further comprising:
 a fluid connection between the process vessel and the jacket inlet for delivering the product fluid to the circulation space. 
 
     
     
         20 . The jacketed firetube system of  claim 13  wherein the vessel further comprises a feed inlet, the system further comprising:
 a fluid connection between the jacket outlet and the feed inlet for delivering the heated heat transfer fluid thereto. 
 
     
     
         21 . The jacketed firetube system of  claim 13  wherein the heat transfer fluid is incompatible with the process fluid, the system further comprising:
 a heat exchanger for flowing the heated, heat transfer fluid and a feed stream of the process fluid therethrough for transferring the heat from the heat transfer fluid to the process fluid in the vessel. 
 
     
     
         22 . The jacketed firetube system of  claim 21  wherein the heat transfer fluid is glycol. 
     
     
         23 . The jacketed firetube system of  claim 14  wherein the firetube further comprises:
 a plurality of thermal conducting passageways for circulating fluid therethrough, each thermal conducting passageway extending generally upwardly from a fluid inlet at a portion of the jacket below the firetube to a fluid outlet at a portion of the jacket above the firetube and having a thermal conductive wall extending through the firetube for conducting heat from the hot gases to the heat transfer fluid circulating therethrough. 
 
     
     
         24 . The jacketed firetube system of  claim 14  wherein the jacket further comprises:
 a plurality of thermal conducting passageways for circulating fluid therethrough, each thermal conducting passageway extending generally upwardly from a fluid inlet at a portion of the vessel below the jacket to a fluid outlet at a portion of the vessel above the jacket and having a thermal conductive wall extending through the jacket for conducting heat to the process fluid. 
 
     
     
         25 . A method for retrofitting a firetube for transferring heat from a firetube to a process fluid in a process vessel, the firetube adapted for connection to a burner at a first burner end and a vent stack at a second outlet end and having a passageway therebetween for directing hot gases from the burner to the vent stack, the method comprising:
 inserting an insert into the first end in thermal communication with and extending along at least a portion of the firetube for forming a circulation circuit for circulating a cool heat transfer fluid therethrough for recovering at least a portion of the heat from the firetube for heating the heat transfer fluid therein.