Pyrolysis furnace with new type radiant tubes arrangement and method of its operation and usage

Abstract

The present invention provides a pyrolysis furnace with new type radiant tubes arrangement and method of its operation and usage. The first pass tubes and second pass tubes of radiant tubes of pyrolysis furnace according to the present invention are located at two parallel planes respectively, the projection of second pass tube of radiant tubes in each group is corresponding to the center location of projection connecting line of two first pass tubes adjacent therewith. The present invention can also employ top burners and bottom burners; the inlet of crossover section is located at middle-upper portion of radiant section wall. The present invention has the feature of uniform heat conduction, high effectiveness, flexible and simple operation and control, and small investment, it is suitable for cracking reaction of hydrocarbons feedstock.

What we claim is  
     
         1 . A pyrolysis furnace with new type radiant tubes arrangement, comprising: 
 a) vertically arranged radiant section ( 3 ), in which burners and multiple groups of radiant tubes ( 7 ) are arranged for high temperature cracking hydrocarbons feedstock;    b) vertically arranged convection section ( 2 ), located above the radiant section and axially shifted therewith, in said convection section multiple groups of convection tubes ( 1 ) are arranged for preheating the hydrocarbons feedstock;    c) horizontally arranged crossover section ( 6 ), connected between said radiant section ( 3 ) and said convection section ( 2 );    characterized in that, 
 said multiple groups radiant tubes ( 7 ) are two pass tubes with different diameters, the first pass tubes and second pass tubes in various groups are located at two parallel planes, and the projection of each second pass tube is corresponding to the center location of the projection connecting line, of the two first pass tubes adjacent therewith, the structure of each first pass tube and second pass tube is the same.  
   
     
     
         2 . The pyrolysis furnace according to  claim 1 , wherein said radiant tubes ( 7 ) are type  2 - 1  of two pass branched tubes with different diameters.  
     
     
         3 . The pyrolysis furnace according to  claim 1 , wherein said radiant tubes ( 7 ) are type  4 - 1  of two pass branched tubes with different diameters.  
     
     
         4 . The pyrolysis furnace according to  claim 1 , wherein said radiant tubes. ( 7 ) are type  1 - 1  of two pass non-branched tubes with different diameters.  
     
     
         5 . The pyrolysis furnace according to claims  1 - 4 , wherein the distance between two adjacent radiant tubes ( 7 ) is 1.8-6.0 times of outer diameter of radiant tubes at the same plane.  
     
     
         6 . The pyrolysis furnace according to claims  1 - 4 , wherein the distance between two adjacent radiant tubes ( 7 ) is 1.8˜4.2 times of outer diameter of radiant tubes at the same plane.  
     
     
         7 . The pyrolysis furnace according to claims  1 - 4 , wherein the distance between two adjacent radiant tubes ( 7 ) is 2.0˜2.8 times of outer diameter of radiant tubes at the same plane.  
     
     
         8 . The pyrolysis furnace according to claims  1 - 4 , wherein the distance between the planes where said first pass tubes and second pass tubes in every group of radiant tubes ( 7 ) are respectively located is 100-600 mm.  
     
     
         9 . The pyrolysis furnace according to claims  1 - 4 , wherein the distance between the planes where said first pass tubes and second pass tubes in every group of radiant tubes ( 7 ) are respectively located is 200-500 mm.  
     
     
         10 . The pyrolysis furnace according to claims  1 - 4 , wherein the distance between the planes where said first pass tubes and second pass tubes in every group of radiant tubes ( 7 ) are respectively located is 300-400 mm.  
     
     
         11 . The pyrolysis furnace according to  claim 1 , wherein bottom burners ( 8 ) and top burners ( 9 ) are simultaneously arranged in said radiant section ( 3 ), more over, said crossover section ( 6 ) is extended out from a middle-upper portion of sidewall of radiant section ( 3 ) and connected to bottom portion of convection section ( 2 ).  
     
     
         12 . The pyrolysis furnace according to  claim 11 , wherein the top wall of said cross over section ( 6 ) is located under the top wall of said radiant section ( 3 ), its distance H is determined by the top/bottom burners ( 9 , 8 ) heat supply ratio R, when R varies in a range of 1:9˜7:3, H is 10%˜50% of total height of radiant section ( 3 ).  
     
     
         13 . The pyrolysis furnace according to  claim 11 , wherein when R varies in a range of 2:8˜6:4, H is 10%˜40% of total height of radiant section ( 3 ).  
     
     
         14 . The pyrolysis furnace according to  claim 11 , wherein when R varies in a range of 2.5:7.5-5:5, H is 15%-40% of total height of radiant section ( 3 ).  
     
     
         15 . The pyrolysis furnace according to  claim 11 , wherein when R varies in a range of 3:7˜4:6, H is 20%˜40% of total height of radiant section ( 3 ).  
     
     
         16 . The pyrolysis furnace according to  claim 11 , wherein the number of said bottom burners ( 8 ) is equal to the number of said top burners ( 9 ), the top or bottom burners are arranged symmetrically about centerline of top or bottom portions and corresponding to one another at top or bottom portion respectively.  
     
     
         17 . A method of high temperature cracking hydrocarbons feedstock by means of a pyrolysis furnace according to any one of claims  1 - 16 , comprising: 
 at convection section ( 2 ), preheating the hydrocarbons feedstock in radiant tubes ( 1 ), utilizing fuel gas of crossover section, came from radiant section ( 3 ); at radiant section ( 3 ), high temperature cracking the preheated hydrocarbons feedstock in radiant tubes ( 7 ), utilizing the heat supplied by top burners ( 9 ) and bottom burners ( 8 ); wherein maintaining the heat supplied by bottom burners ( 8 ) constant, by means of regulating the heat supplied by top burners ( 9 ) so as to satisfy the temperature requirement for cracking different hydrocarbons feedstock.    
     
     
         18 . The use of pyrolysis furnace according to any one of claims  1 - 16  for high temperature cracking Hydrocarbons.