Patent GB-716814-A (GB)
Title: Improvements in or relating to pyrolytic process for endothermically altering a gaseous material
IPC: B01J8/02
Filed: 1952-03-06
Abstract: <PICT:0716814/IV (b)/1> Gaseous or vaporous materials are endothermically altered in a process comprising alternate endothermic alteration and heating phases in which the heat for the endothermic alteration is generated by combustion of a combustible material during a heating phase and in which during an endothermic alteration phase the gaseous or vaporous material is passed through straight channels in a first heat storage mass which is progressively hotter in the direction of flow, thereby to preheat the material to the required endothermic alteration temperature and then through an endothermic alteration zone, the resulting products being quenched by passage through the straight channels of a second heat storage mass which is progressively cooler in the direction of flow of the products.  In a heating phase a flammable mixture of a combustible gas or vapour (for example a heating gas, ammonia or sulphur vapour) is preheated by passage through one of the heat storage masses of at least one component of the flammable mixture and the combustion is completed in the endothermic alteration zone and finally the hot combustion products are passed through the other of the heat storage masses.  The direction of flow of the gases or vapours through the heat storage masses and the endothermic alteration zone during both phases is periodically reversed and the flow in a heating phase may be in a direction opposite to the direction of flow during the succeeding endothermic alteration phase.  Preferably the direction of flow during each phase of each succeeding cycle is in an opposite direction to the flow during the corresponding phase in the preceding cycle.  The process may be applied to the production of low molecular weight hydrocarbons or petroleum hydrocarbons; dehydrogenation products from dehydrogenatable compounds, such as olefins and acetylene from low molecular weight saturated hydrocarbons; aromatic hydrocarbons such as benzene from paraffinic hydrocarbons (including cycloparaffins); isomerization products from hydrocarbons, for example isobutane from butane; dehydration products from alcohols, for example, ethylene from ethyl alcohol; cracked low molecular weight hydrocarbons from high molecular weight hydrocarbons capable of being cracked and carbon black from hydrocarbons.  The temperature of the endothermic alteration zone may be from about 1600 DEG  C. to 500 DEG  C. according to the endothermic alteration to be carried out.  The process may be carried out at atmospheric pressure, for example in the production of olefins or heating gases, at sub-atmospheric pressures of about 0.8-0.2 atmospheres absolute, for example in the production of heating gases rich in unsaturated hydrocarbons, olefins from low molecular weight hydrocarbons, and acetylene from saturated hydrocarbons, or at superatmospheric pressures of up to 5 atmospheres, for example in the production of higher olefins or aromatic hydrocarbons.  Diluents may be added to the gaseous or vaporous material being endothermically altered.  Thus steam may be used in the production of acetylene, olefins, heating gas and aromatic hydrocarbons and in dehydrogenation.  Apparatus for carrying out the process comprises a chamber 1 containing two heat storage masses 2 and 3, which may be of alundum, separated by a division wall 5 and having channels 4 which communicate at their upper ends with an endothermic alteration zone 8 and at their lower ends with chambers 6 or 7, each of which has a gas inlet or outlet pipe.  A heating gas may be admitted to the zone 8 by a pipe 9 for combustion therein to raise the temperature of the apparatus before commencing operation proper, the products of combustion flowing through the heat storage masses in parallel. Pipes and valves are also provided to supply the various gases or vapours for both phases and to enable the necessary alterations in the direction of flow to be made.  In a modification the two heat storage vessels may be disposed in line with each other and are separated by the endothermic alteration zone.  In a further modification a mixing chamber may be provided in the heat storage masses adjacent to the endothermic alteration zone and gases or vapours may be admitted to each of the mixing chambers other than from the channels of the heat storage masses.  Specifications 697,108, [Group XIII], 699,318, [Group XII], and 705,393 are referred to.ALSO:<PICT:0716814/III/1> Gaseous or vaporous materials are endothermically altered in a process comprising alternate endothermic alteration and heating phases in which the heat for the endothermic alteration is generated by combustion of a combustible material during a heating phase and in which during an endothermic alteration phase the gaseous or vaporous material is passed through straight channels in a first heat storage mass which is progressively hotter in the direction of flow thereby to preheat the material to the required endothermic alteration temperature and then through an endothermic alteration zone, the resulting products being quenched by passage through the straight channels of a second heat storage mass which is progressively cooler in the direction of flow of the products.  In a heating phase a flammable mixture of a combustible gas or vapour (for example a heating gas, ammonia or sulphur vapour) is preheated by passage through one of the heat storage masses of at least one component of the flammable mixture and the combustion is completed in the endothermic alteration zone and finally the hot combustion products are passed through the other of the heat storage masses.  The direction of flow of the gases or vapours through the heat storage masses and the endothermic alteration zone during both phases is periodically reversed and the flow in a heating phase may be in a direction opposite to the direction of flow during the succeeding endothermic alteration phase.  Preferably the direction of flow during each phase of each succeeding cycle is in an opposite direction to the flow during the corresponding phase in the preceding cycle.  The process may be applied to the production of heating gas from natural gas, low molecular weight hydrocarbons or petroleum hydrocarbons; dehydrogenation products from dehydrogenatable compounds, such as olefins and acetylene from low molecular weight saturated hydrocarbons; aromatic hydrocarbons such as benzene from paraffinic hydrocarbons (including cycloparaffins); isomerization products from hydrocarbons, for example isobutane from butane; hydrogen cyanide from hydrocarbons and ammonia, nitric oxide from air; dehydration products from alcohols; for example ethylene from ethyl alcohol; hydrazine from ammonia; hydrogen from hydrocarbons; cracked low molecular weight hydrocarbons from high molecular weight hydrocarbons capable of being cracked and carbon black from hydrocarbons.  The temperature of the endothermic alteration zone may be from about 1600 DEG  C. to 500 DEG  C. according to the endothermic alteration to be carried out.  The process may be carried out at atmospheric pressure, for example in the production of olefins or heating gases, at subatmospheric pressures of about 0.8-0.2 atmospheres absolute, for example in the production of heating gases rich in unsaturated hydrocarbons, olefins from low molecular weight hydrocarbons, hydrazine from ammonia and acetylene from saturated hydrocarbons, or at superatmospheric pressures of up to 5 atmospheres, for example in the production of higher olefins or aromatic hydrocarbons.  Diluents may be added to the gaseous or vaporous material being endothermically altered.  Thus steam may be used in the production of acetylene, olefins, heating gas and aromatic hydrocarbons and in dehydrogenation, while hydrogen may be added during the production of hydrogen, hydrazine or carbon black. Apparatus for carrying out the process comprises a chamber 1 containing two heat storage masses 2 and 3, which may be of alundum, separated by a division wall 5 and having channels 4 which communicate at their upper ends with an endothermic alteration zone 8 and at their lower ends with chambers 6 or 7 each of which has a gas inlet or outlet pipe.  A heating gas may be admitted to the zone 8 by a pipe 9 for combustion therein to raise the temperature of the apparatus before commencing operation proper the products of combustion flowing through the heat storage masses in parallel. Pipes and valves are also provided to supply the various gases or vapours for both phases and to enable the necessary alterations in the direction of flow to be made.  In a modification the two heat storage vessels may be disposed in line with each other and are separated by the endothermic alteration zone.  In a further modification a mixing chamber may be provided in the heat storage masses adjacent to the endothermic alteration zone and gases or vapours may be admitted to each of the mixing chambers other than from the channels of the heat storage masses.  Specifications 697,108, [Group XIII], 699,318, [Group XII], and 705,393 are referred to.