Reformed gas as fuel for primary reformer during startup

Abstract

The present invention provides a method and apparatus for recovery of reformed gas produced in a methanol plant during startup. In one aspect, the method for recovery of a reformed gas produced in a methanol plant during startup comprising: a) decreasing the temperature of the methanol plant reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to remove at least some of the water from the reformed gas; and b) using the water removed reformed gas as fuel in a steam reformer.

1 . A method for recovery of a reformed gas produced in a methanol plant during startup comprising:
 a) decreasing the temperature of the methanol plant reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to remove at least some of the water from the reformed gas; and   b) using the water removed reformed gas as fuel in a steam reformer.   
     
     
         2 . The method of  claim 1 , wherein the reformed gas comprises hydrogen is present in an amount ranging from 50 wt % to 92.9 wt % hydrogen based on the total weight of the reformed gas; water is present in an amount ranging from 0 wt % to 2.5 wt % based on the total weight of the reformed gas; nitrogen is present in an amount ranging from 0.1 wt % to 5 wt % based on the total weight of the reformed gas; carbon monoxide is present in an amount ranging from 5 wt % to 20 wt % based on the total weight of the reformed gas; carbon dioxide is present in an amount ranging from 1 wt % to 15 wt % based on the total weight of the reformed gas; and methane is present in an amount ranging from 1 wt % to 8 wt % based on the total weight of the reformed gas. 
     
     
         3 . The method of  claim 1 , wherein the decreased temperature of the reformed gas is about 80° C. to 100° C. 
     
     
         4 . The method of  claim 1  wherein from about 55% to about 99% of the water in the reformed gas is removed. 
     
     
         5 . The method of  claim 1 , wherein removing water from the reformed gas comprises decreasing the temperature of the reformed gas to cool the reformed gas and drying the cooled reformed gas. 
     
     
         6 . The method of  claim 1 , wherein the reformed gas is cooled by passing through a heat exchanger. 
     
     
         7 . The method of  claim 1 , wherein the reformed gas is dried by passing through a separator. 
     
     
         8 . The method of  claim 1 , wherein the reformed gas is further dried by passing through a filter. 
     
     
         9 . The method of  claim 18 , wherein the duty for the heat exchanger ranges from 4.2×10 6  KJ/hr to 6.5×10 6  KJ/hr and the amount of water removed from the reformed gas ranges from 55% to 99%. 
     
     
         10 . The method of  claim 1 , wherein the water removed reformed gas is recycled to a point before entry of natural gas in the methanol plant. 
     
     
         11 . The method of  claim 1 , further comprising adding natural gas to the reformed gas after removing water. 
     
     
         12 . The method of  claim 1 , wherein about 399,300 kg/25 hours of natural gas is added per about 1,339,307 kg/25 hours of reformed gas during plant startup. 
     
     
         13 . The method of  claim 1 , wherein the total amount of natural gas saved by use of reformed gas as fuel is about 6132 MMNTU/25 hrs. 
     
     
         14 . The method of  claim 1 , wherein
 flow of reformed gas ranges from 18448 kg/hr to 84596 kg/hr.   
     
     
         15 . An apparatus for recovery of a reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, where the reformed gas is produced in a methanol plant during startup comprising:
 a closed loop line from a reformed gas flare stack line to a fuel line for a steam reformer;   wherein the closed loop line comprises a heat exchanger; and   wherein the heat exchanger cools the reformed gas.   
     
     
         16 . The apparatus of  claim 15 , wherein the closed loop line cools and dries the reformed gas. 
     
     
         17 . The apparatus of  claim 15 , wherein the loop line further comprises a separator and a filter wherein the separator, or the filter, or the combination thereof, removes from 55% to 99% of the water from the reformed gas. 
     
     
         18 . The apparatus of  claim 15 , wherein downstream of the heat exchanger, the apparatus further comprises a mixer, wherein the mixer adds natural gas to the reformed gas. 
     
     
         19 . A method for recovery of a reformed gas produced in a methanol plant during startup comprising:
 a) decreasing the temperature of the methanol plant reformed gas comprising (1) water in an amount no greater than 2.5 wt %, based on the total weight of the reformed gas, (2) methane in an amount that ranges from 1 wt % to 8 wt %, based on the total weight of the reformed gas, (3) hydrogen, (4) nitrogen, (5) carbon dioxide, and (6) carbon monoxide, to a temperature of about 80° C. to 100° C. to remove at least some of the water from the reformed gas; and   b) using the water removed reformed gas as fuel in a steam reformer;   wherein the reformed gas comprises hydrogen is present in an amount ranging from 50 wt % to 92.9 wt % hydrogen based on the total weight of the reformed gas; water is present in an amount ranging from 0 wt % to 2.5 wt % based on the total weight of the reformed gas; nitrogen is present in an amount ranging from 0.1 wt % to 5 wt % based on the total weight of the reformed gas; carbon monoxide is present in an amount ranging from 5 wt % to 20 wt % based on the total weight of the reformed gas; carbon dioxide is present in an amount ranging from 1 wt % to 15 wt % based on the total weight of the reformed gas; and methane is present in an amount ranging from 1 wt % to 8 wt % based on the total weight of the reformed gas.