Patent GB-705393-A (GB)
Title: Regenerative process and apparatus for chemically endothermically altering a gaseousmaterial
IPC: C10G9/26
Filed: 1951-03-16
Abstract: <PICT:0705393/IV (b)/1> In a continuous cyclic regenerative process for chemically endothermically altering a combustible gaseous material such as a hydrocarbon or a mixture of a hydrocarbon and ammonia, a mixture of the gaseous material and a gas containing free-oxygen is preheated to a temperature at which it is chemically endothermically altered by linearly flowing the gases through uniformly distributed channels having a maximum cross-sectional dimension of 0.75 in. in a first regenerative refractory mass which is progressively hotter in the direction of flow of the gases and then by burning a portion of the preheated mixture and further chemically endothermically altered in a zone intermediate between the first regenerative mass and a second similar regenerative mass, the amount of free oxygen in the mixture being controlled to supply all the heat for the process, finally the gaseous products from the intermediate zone are cooled by passing them through the channels of the second regenerative mass which is progressively cooler in the direction of flow of the gases, the direction of flow of the gases being continuously reversed at predetermined intervals.  The channels in the regenerating masses are preferably of circular cross-section and arranged in staggered rows and are between 4-15 feet in length. The volume of the intermediate zone is not greater than about 60 per cent. of the combined volume of the channels in both regenerative masses.  The process may be operated at atmospheric pressure or at pressures above or below atmospheric and the times of residence of the materials being altered in the various parts of the apparatus are varied according to the nature of the starting material, the products desired and the operating pressure.  The process may be used to produce a fuel gas or gases containing a high proportion of unsaturated hydrocarbons, for example olefines or acetylene, from hydrocarbons such as propane, ethane and natural gas or hydrocyanic acid from a mixture of a hydrocarbon and ammonia.  In using the apparatus shown in Fig. 1 to produce a fuel gas, a mixture of propane and air in non-combustible proportions of approximately 1:2 is passed through lines 20, 23, 21, 17, 15, valve 14, lines 13 and 11 into the channels 4 of a heated mass of refractory material 3, for example made of alundum, and is thereby heated sufficiently to partly crack the hydrocarbon to form a combustible mixture which passes into a zone 8 where limited combustion ensues and further cracking of the hydrocarbon is effected.  The hot gases from the zone 8 pass into a second refractory mass 2 where they give up their sensible heat to the refractory material and leave the chamber by lines 10 and 24, valve 26, lines 27, 29, 33, 35 and 32.  The direction of flow of the gases is reversed at 1 minute intervals by operation of 3-way valves 14 and 26.  The maximum temperature of the refractory masses 2 and 3 is controlled at between 800-900 DEG C. and the initial heating up of the apparatus is effected by introducing combustible material and air into the zone 8 through line 9, the waste gases being withdrawn through lines 37 and 36, valves 16 and 28 being closed.  The apparatus may be worked under increased or reduced pressure by use of pumps 19 and 31 and partial closing of valves 16 and 28.  When used at atmospheric pressures the residence times of the gases in the refractory masses 2 and 3 should not exceed about 0.3 seconds and are preferably between 0.05-0.10 seconds. The residence time of the gases in the zone 8 should not exceed 0.05 seconds and is preferably between 0.01-0.03 seconds.  These residence times are suitable for the production of heating gases, lower olefinic hydrocarbons and the like.  When, however, it is desired to produce acetylene a very short residence time is necessary, preferably below 0.01 seconds, and the pressure is reduced to between 0.2 atmospheres absolute and 0.8 atmospheres absolute.  For the production of higher liquid olefinic hydrocarbons longer residence times at super-atmospheric pressures are employed and at a pressure of two atmospheres the residence times may be as high as 0.3 seconds.  The above stated residence times may be reduced by one half when oxygen is employed in place of air.ALSO:<PICT:0705393/III/1> In a continuous cyclic regenerative process for chemically endothermically altering a combustible gaseous material such as a hydrocarbon or a mixture of a hydrocarbon and ammonia, a mixture of the gaseous material and a gas containing free oxygen is preheated to a temperature at which it is chemically endothermically altered by linearly flowing the gases through uniformly distributed channels having a maximum cross-sectional dimension of 0.75 inches in a first regenerative refractory mass which is progressively hotter in the direction of flow of the gases and then by burning a portion of the preheated mixture it is further chemically endothermically altered in a zone intermediate between the first regenerative mass and a second similar regenerative mass, the amount of free oxygen in the mixture being controlled to supply all the heat for the process, finally the gaseous products from the intermediate zone are cooled by passing them through the channels of the second regenerative mass which is progressively cooler in the direction of the flow of the gases, the direction of flow of the gases being continuously reversed at predetermined intervals.  The channels in the regenerative masses are preferably of circular cross-section and arranged in staggered rows and are between 4-15 feet in length. The volume of the intermediate zone is not greater than about 60 per cent. of the combined volume of the channels in both regenerative masses.  The process may be operated at atmospheric pressure or at pressures above or below atmospheric and the times of residence of the material being altered in the various parts of the apparatus are varied according to the nature of the starting material, the products desired and the operating pressure.  The process may be used to produce a fuel gas or gases containing a high proportion of unsaturated hydrocarbons, for example olefines or acetylene, from hydrocarbons such as propane, ethane and natural gas or hydrocyanic acid from a mixture of a hydrocarbon and ammonia.  In using the apparatus shown in Fig. 1 to produce a fuel gas, a mixture of propane and air in non-combustible proportions of approximately 1 : 2 is passed through lines 20, 23, 21, 17, 15, valve 14, lines 13 and 11 into the channels 4 of a heated mass of refractory material 3, for example made of alundum, and is thereby heated sufficiently to partly crack the hydrocarbon to form a combustible mixture which passes into a zone 8 where limited combustion ensues and further cracking of the hydrocarbon is effected.  The hot gases from the zone 8 pass into a second refractory mass 2 where they give up their sensible heat to the refractory material and leave the chamber by lines 10 and 24, valve 26, lines 27, 29, 33, 35 and 32.  The direction of flow of the gases is reversed at one minute intervals by operation of 3-way valves 14 and 26.  The maximum temperature of the refractory masses 2 and 3 is controlled at between 800-900 DEG  C. and the p  initial heating up of the apparatus is effected by introducing combustible material and air into the zone 8 through line 9, the waste gases being withdrawn through lines 37 and 36, valves 16 and 28 being closed.  The apparatus may be worked under increased or reduced pressure by use of pumps 19 and 31 and partial closing of valves 16 and 28.  When used at atmospheric pressures the residence times of the gases in the refractory masses 2 and 3 should not exceed about 0.3 seconds and are preferably between 0.05-0.10 seconds.  The residence time of the gases in the zone 8 should not exceed 0.05 seconds and is preferably between 0.01-0.03 seconds.  These residence times are suitable for the production of heating gases and the like but when the apparatus is employed for producing hydrocyanic acid by opposing a mixture of a hydrocarbon such as natural gas and ammonia to a very high temperature very short residence times are required and the pressure is reduced to between 0.2 atmospheres absolute and 0.8 atmospheres absolute.  For example with a pressure of one-third atmosphere absolute the residence times in the refractory masses 2 and 3 and the zone 8 are reduced to below 0.01 seconds.  The use of pure oxygen in place of air in the process enables the residence times to be reduced by about one half.