GB855764A - Process of and regenerative furnace for the pyrolysis of an in-gas containing a desired hydrocarbon - Google Patents

Abstract

<PICT:0855764/IV(b)/1> <PICT:0855764/IV(b)/2> <PICT:0855764/IV(b)/3> <PICT:0855764/IV(b)/4> In the cracking of hydrocarbons, e.g. to produce ethylene or acetylene, in a regenerative furnace having first and second regenerative masses with a space between, the major proportion of the combined total sensible heat required to heat the in-gas containing the hydrocarbon and the total reaction heat necessary to crack the hydrocarbon is transferred to the in-gas from the first mass through which it passes, the second mass supplying only a minor proportion. Preferably three masses are used as shown in Fig. 1. In operation the masses are first heated conventionally and then alternate heat and make steps are carried out. In a heat step air is passed into end space 9 and through mass 4 thereby heating the air and cooling the mass while fuel is fed into the space 6, preferably at supersonic speed. The fuel is ignited by the heated air and the combustion products pass through mass 5, space 8 and mass 7 heating the masses to cracking temperature. The hydrocarbon to be cracked, e.g. gas, oil or other petroleum liquid is vaporised and mixed with superheated steam and passed in the opposite direction i.e. first through masses 7 and 5. Since mass 7 is larger than mass 5, preferably four times the length, the spaces being about half the length of the centre mass, the major proportion of heat is transferred to the in-gas from mass 7, but preferably the temperature drops in the two masses should be about equal. The gas is then quenched in the cold mass 4. These two operations are then repeated with opposite directions of flow. In order to ensure that the flow of gases through each mass and each space is quite constant there are arranged flow restricting means 128, 129, and 130 in the apertures of the masses and baffles 104, 105, in the spaces (Fig. 9). The flow restricting means shown more clearly in Fig. 19 are arranged to be at about the hottest point in each mass during the heat step so that carbon deposits are readily burned off. The baffles comprise several baffles 104 and 105 arranged alternately and have interlocking projections and grooves 120. The size of the baffles is such that the free cross-sectional area is the same as the total cross-sectional area of the apertures in the masses. The checkers used to build the mass preferably have "steps" in the faces so that they interlock as shown in Fig. 12 to aid in construction and for rigidity. The grooves should form about 25% of the total cross-sectional area of each checker.ALSO:In the cracking of hydrocarbons to produce gases in a regenerative furnace having first and second regenerative masses with a space between, the major proportion of the combined total sensible heat required to heat the in-gas containing the hydrocarbon and the total reaction heat necessary to crack the hydrocarbon is transferred to the in-gas from the first mass through which it passes, the second mass supplying only a minor proportion. Preferably three masses are used as shown in Fig. 1. In operation the masses are first heated conventionally and then alternate heat and make steps are carried out. In a heat step air is passed into end space 9 and through mass 4 thereby heating the air and cooling the mass while fuel is fed into the space 6, preferably at supersonic speed. The fuel is ignited <PICT:0855764/III/1> <PICT:0855764/III/2> <PICT:0855764/III/3> <PICT:0855764/III/4> by the heated air and the combustion products pass through mass 5, space 8 and mass 7 heating the masses to cracking temperature. The hydrocarbon to be cracked, e.g. gas, oil or other petroleum liquid is vaporized and mixed with superheated steam and passed in the opposite direction, i.e. first through masses 7 and 5. Since mass 7 is larger than mass 5, preferably four times the length, the spaces being about half the length of the centre mass, the major proportion of heat is transferred to the in-gas from mass 7, but preferably the temperature drops in the two masses should be about equal. The gas is then quenched in the cold mass 4. These two operations are then repeated with opposite directions of flow. In order to ensure that the flow of gases through each mass and each space is quite constant there are arranged flow restricting means 128, 129, and 130 in the apertures of the masses and baffles 104, 105, in the spaces (Fig. 9). The flow restricting means shown more clearly in Fig. 19 are arranged to be at about the hottest point in each mass during the heat step so that carbon desposits are readily burned off. The baffles comprise several baffles 104 and 105 arranged alternately and have interlocking projections and grooves 120. The size of the baffles is such that the free cross-sectional area is the same as the total cross-sectional area of the apertures in the masses. The checkers used to build the mass preferably have "steps" in the faces so that they interlock as shown in Fig. 12 to aid in construction and for rigidity. The grooves should form about 25% of the total cross-sectional area of each checker.