Quenching system and process for a quenching system for cooling cracked gas from a cracked gas furnace

Abstract

A quenching system and process cool cracked gas from a cracked gas furnace using different raw materials. A cracked gas furnace, a primary quench exchanger and a secondary quench exchanger are connected in series. A transfer line exchanger for a cooling medium of a gas mixture and steam TLE-G/G is arranged and configured as a secondary quench exchanger connected in series to the primary quench exchanger via a gas transfer line. The TLE-G/G has a feed line conveying the cooling medium. The TLE-G/G is connected via a return line to the cracked gas furnace for returning cooling medium preheated in the TLE-G/G. The TLE-G/G is equipped with a pipeline outputting cracked gas that has been cooled down to temperatures ranging from 450° C. to 300° C. for further processing. A compensator is provided at the upper end of the TLE-G/G behind the cracked gas inlet header.

What is claimed is: 
     
         1 . A quenching system for cooling cracked gas from a cracked gas furnace using different raw materials, the quenching system comprising:
 a cracked gas furnace;   a primary quench exchanger;   a secondary quench exchanger, the primary quench exchanger and the secondary quench exchanger being connected in series, wherein a transfer line exchanger, for a cooling medium comprised of a gas mixture and steam, is arranged and configured as a secondary quench exchanger;   a gas transfer line, wherein the transfer line exchanger is connected in series to the primary quench exchanger via the gas transfer line;   a feed line conveying the cooling medium, comprised of a gas mixture and steam, wherein the feed line is arranged at the transfer line exchanger, at a lower part of the transfer line exchanger, with the transfer line exchanger oriented vertically, in front of an outlet header of the transfer line exchanger;   a return line connecting the transfer line exchanger to the cracked gas furnace for returning cooling medium preheated in the transfer line exchanger to the cracked gas furnace;   a pipeline of the transfer line exchanger for forwarding cracked gas that has been cooled down to temperatures ranging from 450° C. to 300° C. for further processing; and   a compensator, which is provided at an upper end of the transfer line exchanger, with the transfer line exchanger oriented vertically, behind a cracked gas inlet header of the transfer line exchanger.   
     
     
         2 . A quenching system in accordance with  claim 1 ,
 wherein a gas inlet pipe of the feed line of the cooling medium is arranged at a jacket of the transfer line exchanger,   wherein baffles are mounted in the jacket space of the transfer line exchanger such that the cooling medium is guided alternately by 180° around an outside of a tube bundle of the transfer line exchanger during the counterflow process around the baffles of the transfer line exchanger,   wherein a gas outlet pipe of the return line of the preheated cooling medium is arranged at the jacket of the transfer line exchanger at an upper end of the inlet header exchanger, with the transfer line exchanger oriented vertically, and   wherein segments free from tube bundles are provided in the jacket space of the transfer line exchanger in areas of the baffles.   
     
     
         3 . A quenching system in accordance with  claim 2 , wherein a size of the segment free from tube bundles, through which free flow is possible, is dimensioned to be between 10% and 20% of a cross-sectional area of an internal diameter of the jacket of the transfer line exchanger. 
     
     
         4 . A quenching system in accordance with  claim 2 ,
 wherein the bundle tubes of the tube bundle of the transfer line exchanger are arranged in a triangular configuration for a flow of a cooling medium, and   wherein a side length of the triangle of the triangular configuration is 1.2 times to 1.3 times that of a tube diameter of the tubes of the tube bundle.   
     
     
         5 . A quenching system in accordance with  claim 1 , wherein the compensator compensates for different thermal expansions between a bundle tubes and a jacket of the transfer line exchanger and is installed around the jacket of the transfer line exchanger at the upper end, with the transfer line exchanger oriented vertically, behind the inlet header of the cracked gas from the transfer line exchanger. 
     
     
         6 . A quenching system in accordance with  claim 1 , wherein cleaning pipes are arranged adjacent to a tube sheet of the cracked gas outlet header exchanger, with the transfer line exchanger oriented vertically, in the area of a jacket space of the transfer line exchanger. 
     
     
         7 . A quenching system in accordance with  claim 6 ,
 wherein the cleaning pipes comprise two to four closable cleaning pipes with a diameter of 200 mm to 500 mm each that are provided in the area of the jacket space of the transfer line exchanger,   wherein the cleaning pipes are mounted at a distance of 100 mm to 200 mm from the lower tube sheet.   
     
     
         8 . A quenching system in accordance with  claim 1 , wherein according to a predefined level of contamination due to coke deposits in the case of a horizontally oriented transfer line exchanger, two to four cleaning pipes each, with a diameter of 200 mm to 500 mm, are provided lengthwise in the lower area of the jacket space. 
     
     
         9 . A process for a quenching system for cooling cracked gas from a cracked gas furnace using different raw materials, the quenching system comprising a cracked gas furnace, a primary quench exchanger and a secondary quench exchanger, which are connected in series, the process comprising:
 arranging and configuring a transfer line exchanger, for a cooling medium comprised of a gas mixture and steam, as the secondary quench exchanger;   connecting the transfer line exchanger in series to the primary quench exchanger via a gas transfer line;   with a feed line, conveying the cooling medium, comprised of a gas mixture and steam, wherein the feed line is arranged at the transfer line exchanger at a lower part in front of an outlet header, with the transfer line exchanger oriented vertically;   connecting the transfer line exchanger via a return line to the cracked gas furnace for returning cooling medium preheated in the transfer line exchanger;   providing the transfer line exchanger with a pipeline for forwarding cracked gas that has been cooled down to temperatures ranging from 450° C. to 300° C. for further processing; and   providing a compensator at an upper end of the transfer line exchanger, behind the cracked gas inlet header.   
     
     
         10 . A process for a quenching system in accordance with  claim 9 ,
 wherein a gas inlet pipe of the feed line of the cooling medium is arranged at a jacket of the transfer line exchanger,   wherein a plurality of baffles are mounted in a jacket space of the transfer line exchanger, wherein the number of baffles depends on and is to be determined by a respective predefined load,   wherein the cooling medium is guided alternately by 180° around the outside of a tubes bundle during a counterflow process around the baffles of the transfer line exchanger,   wherein a gas outlet pipe for the return line of the preheated cooling medium is arranged at the jacket of the transfer line exchanger at the upper end in front of the inlet header exchanger, with the transfer line exchanger oriented vertically, and   wherein segments free from tube bundles are provided in the jacket space of the transfer line exchanger in areas of the baffles.   
     
     
         11 . A process for a quenching system in accordance with  claim 10 , wherein the size of the segment, through which free flow is possible, is dimensioned to be between 10% and 20% of the cross-sectional area of the internal diameter of the jacket of the transfer line exchanger. 
     
     
         12 . A process for a quenching system in accordance with  claim 10 ,
 wherein the bundle tubes of the transfer line exchanger are arranged in a triangular configuration for a flow of a cooling medium, and   wherein a side length of a triangle of the triangular configuration is 1.2 times to 1.3 times that of a tube diameter of the bundle tubes.   
     
     
         13 . A process for a quenching system in accordance with  claim 9 , wherein the compensator is configured to compensate different thermal stresses between bundle tubes and a jacket of the transfer line exchanger and is installed around the jacket of the transfer line exchanger at the upper end behind the inlet header of the cracked gas from the transfer line exchanger. 
     
     
         14 . A process for a quenching system in accordance with  claim 9 , wherein cleaning pipes are arranged adjacent to a tube sheet of the cracked gas outlet header, with the transfer line exchanger oriented vertically, in an area of a jacket space of the transfer line exchanger. 
     
     
         15 . A process for a quenching system in accordance with  claim 14 ,
 wherein the cleaning pipes comprise two to four closable cleaning pipes with a diameter of 200 mm to 500 mm each, which are provided in the area of the jacket space of the transfer line exchanger, and   wherein the cleaning pipes are mounted at a distance of 100 mm to 200 mm from the lower tube sheet of the outlet header of the transfer line exchanger.   
     
     
         16 . A process for a quenching system in accordance with  claim 9 , wherein according to a predefined level of contamination due to coke deposits, with the transfer line exchanger oriented horizontally, two to four cleaning pipes each, having a diameter of 200 mm to 500 mm, are provided lengthwise in the lower area of the jacket space.