Use of a mixture of carbon dioxide and nitrogen as an inerting and flow medium in powder injection systems for pulverized coal gasification under pressure

Abstract

A powder injection system for use in pulverized coal gasification under pressure is provided. The powder injection system includes a reservoir for stocking the pulverized coal, a plurality of power injection tubes and a metering unit. A mixture of nitrogen and carbon dioxide is fed to the components that are at operating pressure, namely the powder injection tube and the metering unit, as the inerting and flow medium or fluidizing medium. The nitrogen and carbon dioxide mixture-carrying components are heated in such a manner that the temperature is above the threshold of the diphase range. A method is also provided. The method allows reduction of the nitrogen content in the product gas, which nitrogen is caused by the powder injection system, especially when used in pulverized coal gasification under pressure to produce a synthesis gas for the production of different hydrocarbons.

1 .- 4 . (canceled) 
   
   
       5 . A method for operating a powder injection system for a pulverized coal gasification under pressure, comprising:
 applying an ambient pressure to a reservoir which supplies the pulverized coal;   applying a high operating pressure to a plurality of powder injection tubes and to a metering vessel which heats up the reservoir;   feeding heated nitrogen to the reservoir as an inerting and dispersal medium;   feeding a nitrogen and carbon dioxide mixture to a powder injection transfer tube as an inerting and flow medium; and   feeding the nitrogen and carbon dioxide mixture to the metering vessel as a fluidization medium.   
   
   
       6 . The method as claimed in  claim 5 , wherein the supplied nitrogen and carbon dioxide mixture is heated up to a temperature above a threshold to a two-phase region at a high process pressure in a high-pressure region of the powder injection system. 
   
   
       7 . A method as claimed in  claim 5 , wherein a nitrogen and carbon dioxide mixture ratio is dimensioned according to a highest permitted proportion of nitrogen at a flow control unit to a reactor in accordance with a highest permissible injection of nitrogen in a product gas of a gasification system. 
   
   
       8 . The method as claimed in  claim 5 , wherein the high operating pressure is 40 bar. 
   
   
       9 . The method as claimed in  claim 5 , wherein the nitrogen and carbon dioxide mixture is used as an injection gas and introduced into a plurality of powder flow lines. 
   
   
       10 . The method as claimed in  claim 5 , wherein the nitrogen and carbon dioxide mixture ratio is 75/25. 
   
   
       11 . The method as claimed in  claim 5 , wherein the nitrogen and carbon dioxide mixture ratio is 60/40. 
   
   
       12 . The method as claimed in  claim 5 , wherein the nitrogen and carbon dioxide mixture ratio is 50/50. 
   
   
       13 . The method as claimed in  claim 5 , wherein the nitrogen and carbon dioxide mixture ratio is 40/60. 
   
   
       14 . The method as claimed in  claim 5 , wherein the nitrogen and carbon dioxide mixture ratio is 25/75. 
   
   
       15 . An arrangement for a powder injection for pulverized coal gasification under pressure, comprising:
 a reservoir to which an ambient pressure is applied, the reservoir supplies the pulverized coal;   an injection tube to which a high operating pressure may be applied;   a metering vessel to which a high operating pressure may be applied,   wherein when the high operating pressure is applied to the metering vessel, the reservoir is heated up,   wherein heated nitrogen is fed to the reservoir as an inerting and loosening medium,   wherein a nitrogen and carbon dioxide mixture is fed to the powder injection transfer tube as an inerting and flow medium, and   wherein the nitrogen and carbon dioxide mixture is fed to the metering vessel as a fluidization medium.   
   
   
       16 . The arrangement as claimed in  claim 15 , wherein the supplied nitrogen and carbon dioxide mixture is heated up to a temperature above a threshold to a two-phase region at a high process pressure in a high-pressure region of the powder injection system. 
   
   
       17 . The arrangement as claimed in  claim 15 , wherein a nitrogen and carbon dioxide mixture ratio is dimensioned according to a highest permitted proportion of nitrogen at a flow control unit to a reactor in accordance with a highest permissible injection of nitrogen in a product gas of a gasification system. 
   
   
       18 . The arrangement as claimed in  claim 15 , wherein the high operating pressure is 40 bar. 
   
   
       19 . The arrangement as claimed in  claim 15 , wherein the nitrogen and carbon dioxide mixture is used as an injection gas and introduced into a plurality of powder flow lines. 
   
   
       20 . The arrangement as claimed in  claim 15 , wherein the nitrogen and carbon dioxide mixture ratio is 75/25. 
   
   
       21 . The arrangement as claimed in  claim 15 , wherein the nitrogen and carbon dioxide mixture ratio is 60/40. 
   
   
       22 . The arrangement as claimed in  claim 15 , wherein the nitrogen and carbon dioxide mixture ratio is 50/50. 
   
   
       23 . The arrangement as claimed in  claim 15 , wherein the nitrogen and carbon dioxide mixture ratio is 40/60. 
   
   
       24 . The arrangement as claimed in  claim 15 , wherein the nitrogen and carbon dioxide mixture ratio is 25/75.