Cooling screen with variable tube diameter for high gasifier power

Abstract

A liquid-cooled cooling screen for an entrained-flow gasifier for gasification of fuels in dust or liquid form using a gasifier agent containing free oxygen, at pressures between atmospheric pressure and 8 MPa and gasification temperatures between 1200 and 1900° C. The liquid-cooled cooling screen of which the cooling pipes in the central cylindrical section have thinner walls than the cooling pipes in the lower and upper conical sections. A cooling screen design has sufficient strength under high pressure difference over the cooling screen wall, a pipe wall thickness which ensures reliable operation of the cooling screen and high heat throughput, and pressure equalization between the cooling screen gap and the reaction chamber under all operating circumstances.

1 . An entrained-flow gasifier for the gasification of fuels in dust or liquid form using a free oxygen-containing gasifying agent at pressures between atmospheric pressure and 8 MPa and at gasification temperatures between 1200 and 1900° C., comprising:
 a reaction chamber connected to a quenching chamber arranged therebelow via a guide pipe in a pressure shell, 
 a cooling screen, wherein the reaction chamber is delimited by the cooling screen, 
 a gasification burner configured to be arranged at the upper end of the reaction chamber, 
 wherein a cooling screen gap between the cooling screen and pressure shell is flushed with an inert gas, 
 wherein the cooling screen is configured by the winding of a number of cooling screen tubes through which a cooling liquid flows, 
 wherein the cooling screen has a tapering conical cooling screen portion at the upper end, a tapering conical cooling screen portion at the lower end and a central cylindrical cooling screen portion therebetween, 
 wherein the cooling screen tubes are configured as a thick-walled cooling screen tube in the region of the lower and the upper cooling screen portion and as a thin-walled cooling screen tube in the region of the central cooling screen portion. 
 
     
     
         2 . The entrained-flow gasifier as claimed in  claim 1 ,
 wherein a setting angle of the conical cooling screen portion has an angle of 35° to 60°.   
     
     
         3 . The entrained-flow gasifier as claimed in  claim 1 ,
 wherein the cooling screen is supported by feet which are each fixedly connected to at least three tube windings of the conical cooling screen portion at the lower end and to three tube windings in the cylindrical cooling screen portion situated thereabove.   
     
     
         4 . The entrained-flow gasifier as claimed in  claim 1 ,
 wherein an outside diameter of the cooling screen tube is constant and the transition from the thick-walled cooling screen tube to the thin-walled cooling screen tube is configured to be smooth in an inner part of the cooling screen tube.   
     
     
         5 . The entrained-flow gasifier as claimed in  claim 3 ,
 wherein the transition from the thick-walled cooling screen tube to the thin-walled cooling screen tube is arranged in a horizontal direction between the feet, and at least one thick-walled cooling screen tube is arranged above the foot in a vertical direction.   
     
     
         6 . The entrained-flow gasifier as claimed in  claim 1 ,
 wherein the thick-walled cooling screen tube is continued into the cylindrical cooling screen portion to such an extent that at least one cooling screen tube achieves half a revolution in the cylindrical cooling screen portion.   
     
     
         7 . The entrained-flow gasifier as claimed in  claim 1 ,
 wherein the cooling screen is configured with a plurality of tubes which are wound in parallel.   
     
     
         8 . The entrained-flow gasifier as claimed in  claim 1 ,
 wherein flushing and pressure-equalizing tubes are arranged at an upper end of the cooling screen.   
     
     
         9 . The entrained-flow gasifier as claimed in  claim 8 ,
 wherein the flushing and pressure-equalizing tubes bear on bearing plates and the remaining gap is sealed with fiber mats.   
     
     
         10 . The entrained-flow gasifier as claimed in  claim 9 ,
 wherein each bearing plate is connected to a cooling screen tube.   
     
     
         11 . The entrained-flow gasifier as claimed in  claim 7 ,
 wherein the cooling screen is configured with eight tubes which are wound in parallel.