Feed ratio control for hter

Abstract

A method for designing the construction of a Heat Exchange Reformer (HER) to minimise metal dusting, and a method for improved thermal control in a Heat Exchange Reformer (HER). By analysis of various parameters related to a Main Reforming Unit (MRU) and a Heat Exchange Reformer (HER), improved thermal control and reduced metal dusting is achieved.

1 . A method for designing the construction of a Heat Exchange Reformer (HER) to minimise metal dusting, said HER being part of a synthesis gas production unit, said synthesis gas production unit comprising a Main Reforming Unit (MRU) and a Heat Exchange Reformer (HER), wherein the effluent from the MRU is arranged so as to provide heat to the HER, and wherein a hydrocarbon feedstock is arranged so as to pass in parallel through both the MRU and the HER, thus providing:
 a. an MRU hydrocarbon feed having an MRU steam-to-carbon ratio (MRU S/C ), an effluent outlet temperature (T MRU ) and a MRU hydrocarbon flow rate (F MRU ) and   b. an HER hydrocarbon feed having an HER steam-to-carbon ratio (HER S/C ) and an HER hydrocarbon flow rate (F HER ), said method comprising;
 determining how the temperature profile within the HER varies with the distance from the inlet of the HER as a function of the ratio of F HER /F MRU , the MRU outlet temperature (T MRU ), the MRU steam-to-carbon ratio (MRU S/C ), the HER steam-to-carbon ratio (HER S/C ) and the total hydrocarbon flow rate (F MRU +F HER ); 
 from said temperature profile, determining a distance (A) from the inlet of the HER at which metal dusting is not significant; 
 at a distance greater than said distance (A) from the inlet of the HER, constructing the HER from a first metal has a higher resistance to metal dusting; and 
 at a distance less than said distance (A) from the inlet of the HER, constructing the HER from a second metal which has a lower resistance to metal dusting than said first metal. 
   
     
     
         2 - 5 . (canceled) 
     
     
         6 . The method according to  claim 1 , wherein the HER is a bayonet-type HER or a double-tube type HER. 
     
     
         7 . A method according to  claim 1 , wherein said method comprises decreasing the ratio of F HER /F MRU . 
     
     
         8 . A method according to  claim 1 , wherein the MRU provides synthesis gas to a hydrogen plant, ammonia plant, methanol plant and/or synfuel plant. 
     
     
         9 . A method according to  claim 1 , wherein the MSR is selected from a tubular reformer, an air-blown secondary reformer, an oxygen-blown secondary reformer and an autothermal reformer. 
     
     
         10 . A method according to  claim 1 , wherein the effluent from the MRU is arranged to flow co-current or counter-current with the HER hydrocarbon feed in the HER. 
     
     
         11 . A method according to  claim 1 , wherein the hydrocarbon feedstock comprises natural gas, LPG, naphtha, reformulated gasoline (RFG) or a mixture of LPG and naphtha. 
     
     
         12 . A method according to  claim 1 , wherein said synthesis gas production unit further includes a pre-reformer arranged upstream the MRU and/or the HER. 
     
     
         13 . Use of a method according to  claim 6 , for reduced metal dusting in the HER.