Optimized reactor centerpipe

Abstract

A method of increasing aromatic yield, or hydrogen yield, or reformate octane, or combinations thereof for a selected set of operating conditions in a reforming process is described. The process uses a centerpipe having a top connection section, a bottom connection section, and an intermediate connection section in which the diameter of the intermediate section is less than a diameter of the top connection section, or the bottom connection section, or both. This arrangement can be present in one or more of the reforming reactors in the reforming reaction zone. A method of optimizing the diameter of the intermediate section is also described.

1 . A method of increasing aromatic yield, or hydrogen yield, or reformate octane, or combinations thereof for a selected set of operating conditions in a reforming process comprising:
 providing a feed to a reforming reaction zone comprising at least two reforming reactors, the first reforming reactor comprising a first shell, a first centerpipe positioned in the first shell, and a first catalyst disposed between the first shell and the first centerpipe, the first centerpipe having a first top connection section having a first top diameter, a first bottom connection section having a first bottom diameter, and a first intermediate section having a first intermediate diameter, the first intermediate section comprising first openings sized to permit a flow of feed and to prevent a flow of the first catalyst, and the second reforming reactor comprising a second shell, a second centerpipe positioned in the second shell, and a second catalyst disposed between the second shell and the second centerpipe, the second centerpipe having a second top connection section having a second top diameter, a second bottom connection section having a second bottom diameter, and a second intermediate section comprising second openings sized to permit a flow of feed and to prevent a flow of the second catalyst, the second intermediate section having a second intermediate diameter less than the second top diameter, or the second bottom diameter, or both of the second centerpipe, wherein the second intermediate diameter of the second intermediate section is less than a first intermediate diameter of the first intermediate section, wherein a diameter of the first shell does not change and a diameter of the second shell does not change, and wherein a reactor tangent length of the first shell does not change and a reactor tangent length of the second shell does not change;   passing the feed through the first and second catalyst in the first and second reactors forming a reaction product; and   removing the reaction product from the reforming reaction zone.   
     
     
         2 . The method of  claim 1  wherein the second centerpipe replaces a centerpipe in an existing reforming reactor comprising a top connection section, a bottom connection section, and an intermediate section, wherein a diameter of the top connection section, the bottom connection section, and the intermediate section of the existing reforming reactor are the same. 
     
     
         3 . The method of  claim 1  wherein the first top diameter and the first bottom diameter of the first reforming reactor are the same as the second top diameter and the second bottom diameter of the second reforming reactor. 
     
     
         4 . The method of  claim 1  wherein a ratio of the second intermediate diameter of the second intermediate section to the first intermediate diameter of the first intermediate section is in a range of 0.6 to 0.95. 
     
     
         5 . The method of  claim 1  wherein a difference between the first intermediate diameter of the first intermediate section of the first reforming reactor and the second intermediate diameter of the second intermediate section of the second reforming reactor is in a range of 1 in to 20 in, and wherein the first intermediate diameter of the first intermediate section is larger than the second intermediate diameter of the second intermediate section. 
     
     
         6 . The method of  claim 1  wherein the first or second centerpipe or both of the reforming reaction zone replace a first or second existing centerpipe or both in an existing reforming reaction zone comprising at least two reforming reactors, the first or second centerpipe or both in the existing reforming reactor comprising a first or second existing top connection section having a first or second existing top diameter, a first or second existing bottom connection section having a first or second existing bottom diameter, and a first or second intermediate section having a first or second existing intermediate diameter, wherein a ratio of the first or second intermediate diameter of the first or second replacement intermediate section of the reforming reaction zone to the first or second existing intermediate diameter of the intermediate section of the first or second existing centerpipe or both in the existing reforming reactor is in a range of 0.6 to 0.95. 
     
     
         7 . The method of  claim 1  wherein the first top diameter, the first bottom diameter, and first intermediate diameter of the first reforming reactor are the same. 
     
     
         8 . The method of  claim 1  wherein the first reforming reactor further comprises a first scallop comprising a front face, a back face, and opposing sides, the first scallop positioned between first shell and the first centerpipe wherein the first catalyst is disposed between the front face of the first scallop and the first centerpipe; or wherein the second reforming reactor further comprises a second scallop comprising a front face, a back face, and opposing sides, the second scallop positioned between second shell and the second centerpipe wherein the second catalyst is disposed between the front face of the second scallop and the second centerpipe; or both. 
     
     
         9 . The method of  claim 1  wherein a layer of the first intermediate section of the first centerpipe has a non-uniform pattern of the first openings, or a layer of the second intermediate section of the second centerpipe has a non-uniform pattern of the second openings, or both. 
     
     
         10 . The method of  claim 9  wherein the nonuniform pattern of the first openings comprises an area of the first openings near the bottom of the centerpipe less than an area of the first openings near the top of the centerpipe; or the nonuniform pattern of the second openings comprises an area of the second openings near the bottom of the centerpipe less than an area of the second openings near the top of the centerpipe; or both. 
     
     
         11 . The method of  claim 1  wherein the reforming reaction zone comprises at least one additional reforming reactor comprising at least one additional shell, at least one additional centerpipe positioned in the at least one additional shell, and at least one additional catalyst disposed between the at least one additional shell and the at least one additional centerpipe, the at least one additional centerpipe having a top connection section having an additional top diameter, a bottom connection section having an additional bottom diameter, and an intermediate section having an additional intermediate diameter, the intermediate section of the at least one additional reforming reactor comprising additional openings sized to permit the flow of feed and to prevent the flow of the at least one additional catalyst, the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor being less than the first top diameter, or the first bottom diameter, or both of the intermediate section of the at least one additional reforming reactor, wherein the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor is less than the first intermediate diameter of the first intermediate section, or the second intermediate diameter of the second intermediate section, or both, wherein a diameter of the at least one additional shell does not change, and wherein a reactor tangent length of the at least one additional shell does not change. 
     
     
         12 . The method of  claim 1  further comprising optimizing the aromatic yield by determining an optimized centerpipe diameter:
 1) reducing the second intermediate diameter of the second centerpipe by a selected amount of the first intermediate diameter of the first centerpipe; 
 2) calculating an increased catalyst volume in the second reforming reactor based on the reduced second intermediate diameter of the second centerpipe; 
 3) determining an aromatic yield increase based on the increased catalyst volume, a previous operating reactor pressure at the original reactor inlet temperature using a catalytic yield performance prediction model; 
 4) calculating a revised reactor pressure based on the reduced second intermediate diameter of the second centerpipe; 
 5) determining a new aromatic yield increase based on the increased catalyst volume and the revised reactor pressure using a catalytic yield performance prediction model; 
 6) comparing the new aromatic yield increase with a previous aromatic yield increase;
 a) if the new aromatic yield increase is less than the previous aromatic yield increase, select the second intermediate diameter of the second centerpipe to be the first intermediate diameter of the first centerpipe minus the selected amount; 
 b) if the new aromatic yield increase is greater than the previous aromatic yield increase, return to step 1) and increase the selected amount of the first intermediate diameter of the first centerpipe. 
 
 
     
     
         13 . A method of increasing aromatic yield, or hydrogen yield, or reformate octane, or combinations thereof for a selected set of operating conditions in a reforming process comprising:
 providing a feed to a reforming reaction zone comprising at least two reforming reactors, the first reforming reactor comprising a first shell, a first scallop, and a first centerpipe, the first scallop comprising a front face, a back face, and opposing sides, the first scallop positioned between first shell and the first centerpipe, and a first catalyst disposed between the first scallop and the first centerpipe, the first centerpipe having a first top connection section having a first top diameter, a first bottom connection section having a first bottom diameter, and a first intermediate section having a first intermediate diameter, the first intermediate section comprising first openings sized to permit a flow of feed and to prevent a flow of the first catalyst, and the second reforming reactor comprising a second shell, a second scallop, and a second centerpipe, the second scallop comprising a front face a back face, and opposing sides, the second scallop positioned between the second shell and the second centerpipe, and a second catalyst disposed between the second scallop and the second centerpipe, the second centerpipe having a second top connection section having a second top diameter, a second bottom connection section having a second bottom diameter, and a second intermediate section comprising second openings sized to permit a flow of feed and to prevent a flow of the second catalyst, the second intermediate section having a second intermediate diameter less than the second top diameter, or the second bottom diameter, or both of the second centerpipe, wherein the second intermediate diameter of the second intermediate section is less than a first intermediate diameter of the first intermediate section, wherein a diameter of the first shell does not change and a diameter of the second shell does not change, and wherein a reactor tangent length of the first shell does not change, and a reactor tangent length of the second shell does not change, and wherein a ratio of the second intermediate diameter of the second intermediate section to the first intermediate diameter of the first intermediate section is in a range of 0.6 to 0.95;   passing the feed through the first and second catalyst in the first and second reactors forming a reaction product; and   removing the reaction product from the reforming reaction zone.   
     
     
         14 . The method of  claim 13  wherein the second centerpipe replaces a centerpipe in an existing reforming reactor comprising a top connection section, a bottom connection section, and an intermediate section, wherein a diameter of the top connection section, the bottom connection section, and the intermediate section of the existing reforming reactor are the same. 
     
     
         15 . The method of  claim 13  wherein the first top diameter and the first bottom diameter of the first reforming reactor are the same as the second top diameter and the second bottom diameter of the second reforming reactor. 
     
     
         16 . The method of  claim 13  wherein a difference between the first intermediate diameter of the first intermediate section of the first reforming reactor and the second intermediate diameter of the second intermediate section of the second reforming reactor is in a range of 1 in to 20 in, and wherein the first intermediate diameter of the first intermediate section is larger than the second intermediate diameter of the second intermediate section. 
     
     
         17 . The method of  claim 1  wherein the first or second centerpipe or both of the reforming reaction zone replace a first or second existing centerpipe or both in an existing reforming reaction zone comprising at least two reforming reactors, the first or second centerpipe or both in the existing reforming reactor comprising a first or second existing top connection section having a first or second existing top diameter, a first or second existing bottom connection section having a first or second existing bottom diameter, and a first or second intermediate section having a first or second existing intermediate diameter, wherein a ratio of the first or second intermediate diameter of the first or second replacement intermediate section of the reforming reaction zone to the first or second existing intermediate diameter of the intermediate section of the first or second existing centerpipe or both in the existing reforming reactor is in a range of 0.6 to 0.95. 
     
     
         18 . The method of  claim 13  wherein a layer of the first intermediate section of the first centerpipe has a non-uniform pattern of the first openings, or a layer of the second intermediate section of the second centerpipe has a non-uniform pattern of the second openings, or both; and wherein the nonuniform pattern of the first openings comprises an area of the first openings near the bottom of the centerpipe less than an area of the first openings near the top of the centerpipe; or the nonuniform pattern of the second openings comprises an area of the second openings near the bottom of the centerpipe less than an area of the second openings near the top of the centerpipe; or both. 
     
     
         19 . The method of  claim 13  wherein the reforming reaction zone comprises at least one additional reforming reactor comprising at least one additional shell, at least one additional scallop, the at least one additional scallop comprising a front face, a back face, and opposing sides, the at least one additional scallop positioned between the at least one addition shell and the at least one additional centerpipe, and at least one additional catalyst disposed between the at least one additional scallop and the at least one additional centerpipe, the at least one additional centerpipe having a top connection section having an additional top diameter, a bottom connection section having an additional bottom diameter, and an intermediate section having an additional intermediate diameter, the intermediate section of the at least one additional reforming reactor comprising additional openings sized to permit the flow of feed and to prevent the flow of the at least one additional catalyst, the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor being less than the first top diameter, or the first bottom diameter, or both of the intermediate section of the at least one additional reforming reactor, wherein the additional intermediate diameter of the intermediate section of the at least one additional reforming reactor is less than the first intermediate diameter of the first intermediate section, or the second intermediate diameter of the second intermediate section, or both, wherein a diameter of the at least one additional shell does not change, and wherein a reactor tangent length of the at least one additional shell does not change. 
     
     
         20 . The method of  claim 13  further comprising optimizing the aromatic yield by determining an optimized centerpipe diameter:
 1) reducing the second intermediate diameter of the second centerpipe by a selected amount of the first intermediate diameter of the first centerpipe; 
 2) calculating an increased catalyst volume in the second reforming reactor based on the reduced second intermediate diameter of the second centerpipe; 
 3) determining an aromatic yield increase based on the increased catalyst volume, a previous operating reactor pressure at the original reactor inlet temperature using a catalytic yield performance prediction model; 
 4) calculating a revised reactor pressure based on the reduced second intermediate diameter of the second centerpipe; 
 5) determining a new aromatic yield increase based on the increased catalyst volume and the revised reactor pressure using a catalytic yield performance prediction model; 
 6) comparing the new aromatic yield increase with a previous aromatic yield increase;
 a) if the new aromatic yield increase is less than the previous aromatic yield increase, select the second intermediate diameter of the second centerpipe to be the first intermediate diameter of the first centerpipe minus the selected amount; 
 b) if the new aromatic yield increase is greater than the previous aromatic yield increase, return to step 1) and increase the selected amount of the first intermediate diameter of the first centerpipe.