Method and apparatus for a constant steam generation from the waste heat of an alkane dehydrogenation

Abstract

The invention relates to a process and a device for an as constant as possible supply of steam flow from an alkane dehydrogenation, the process being carried out by passing a hydrocarbonaceous gas through reaction tubes loadable with a catalyst, and the reaction tubes, which are sealed towards the outside, running through a heating chamber which is heatable by means of burners, and the catalyst being regenerated for the reaction in a cyclic operating mode, in which the reaction is endothermic and the regeneration of the catalyst non-endothermic, and the capacity of the main burners is reduced during the regeneration of the catalyst, in which auxiliary burners, which serve to keep up the production of hot flue gas during the regeneration of the catalyst, are installed at the inlet of the flue gas duct to produce additional hot flue gas which is used for generating an as constant as possible amount of steam from the waste heat of the process.

1 .- 11 . (canceled) 
     
     
         12 . A process for the generation of a constant amount of steam for the waste heat of an alkane dehydrogenation process, comprising:
 arranging a fixed-bed catalyst in one or more reaction tubes and carrying out therein an endothermic reaction by passing a reaction gas mixture through the reaction tube(s);   heating the reaction tube(s) from the outside by combustion of a fuel gas in a heating chamber housing the reaction tubes, forming a flue gas stream;   performing the reaction in the reaction tube(s) in a temporally cyclic operating mode, a period of time not used for the reaction being used for the regeneration of the catalyst by passing an oxygen-containing gas, water vapour-containing gas, or mixture thereof across the catalyst, and   utilizing the flue gas stream for steam generation by a steam generator having a heat exchange surface; and   increasing the quantity of the flue gas stream which contacts the heat exchange surface of the steam generator during regeneration by activating at least one auxiliary burner installed in the flue gas stream behind the reaction tubes to be heated, this burner producing a flue gas stream which does not contact the reaction tubes.   
     
     
         13 . The process of  claim 12 , wherein the auxiliary burner(s) are used to increase the temperature of the flue gas stream on the heat exchange surfaces of the steam generator during the regeneration. 
     
     
         14 . The process of  claim 12 , wherein the auxiliary burners are equipped with a control device and the flue gas duct which is heated by means of the auxiliary burner is provided with a temperature measuring device to control the auxiliary burners by means of the temperature in the flue gas duct. 
     
     
         15 . The process of  claim 12 , wherein the auxiliary burners are equipped with a control device and the steam generators which are heated by the auxiliary burner are equipped with a steam flow meter to control the auxiliary burners by the amount of produced steam. 
     
     
         16 . The process of  claim 12 , wherein the endothermic process with the catalyst to be regenerated is an alkane dehydrogenation process in which an alkane is converted into an alkene by the release of hydrogen. 
     
     
         17 . The process of  claim 12 , wherein the endothermic process with the catalyst to be regenerated is an alkane dehydrogenation process in which an alkane is converted into an alkene by the release of hydrogen and the hydrogen is oxidised in a subsequent process step in which a further dehydrogenation of not yet converted alkane is achieved. 
     
     
         18 . A facility for the generation of a constant amount of steam from the waste heat of an alkane dehydrogenation process, comprising:
 a reactor with heating chamber for carrying out an endothermic reaction with integrated reaction tubes which are loaded with a catalyst;   an inlet for a reaction gas and an outlet for a product gas in the reaction tubes;   one or more main burners which do not contact the catalyst or the reaction gas and which heat the reaction tubes in the heating chamber from the outside;   a flue gas duct at the end of the heating chamber and one or more steam generator(s) in the flue gas duct; and   one or more auxiliary burner(s) installed in the inlet of the flue gas duct in the flue gas stream behind the reaction tubes and upstream of the entry into the steam generator or generators.   
     
     
         19 . The facility of  claim 18 , wherein the auxiliary burner(s) are equipped with an ignition device. 
     
     
         20 . The facility of  claim 18 , wherein the auxiliary burner(s) are equipped with a control device which serves to control the capacity of the auxiliary burner(s). 
     
     
         21 . The facility of  claim 18 , wherein the flue gas duct is equipped with a device for measuring the flue gas temperature in the flue gas duct, by which the capacity of the auxiliary burner(s) is controlled. 
     
     
         22 . The facility of  claim 18 , wherein the steam generators which are heated by the auxiliary burner(s) are equipped with a steam flow meter to control the capacity of the auxiliary burner(s).