GB282541A - A process of obtaining volatile hydrocarbons such as gasoline, benzene or other hydro-carbon oils contained in natural gas, coal gas, water gas, air or other gaseous mixtures, and apparatus therefor - Google Patents

Abstract

282,541. Okochi, M. Nov. 12, 1926. Gases, separating mixtures of.-In the recovery of volatile hydrocarbons such as gasolene, ben. zene, naphthalene, &c., from natural gas, coal gas, water gas, air, &c., adsorption or absorption by means of silica gel, charcoal, fullers earth, &c., is effected at a low temperature and at either atmospheric or higher pressure, cooling being effected by sudden expansion of the previously compressed crude gas. Another part of the compressed gas may be employed for cooling a condenser in which the adsorbed substances are recovered after distillation from a second adsorption tower used alternately with the first. In one arrangement of plant, there are three paths for crude gas entering either adsorption tower 7 or 7'. A part of the crude gas from a pipe. I enters a compressor 2, and is then divided, one portion passing through a cooler 3, valve 5, and expansion valve 6 to the adsorption tower 7, while the remainder, after passage through a cooler 3<1>, enters through an expansion valve 13<1> into a coil 14<1> within a condenser 27<1> receiving the vapour distilled from the second adsorption tower 7<1>; from the coil 14<1> the gas is conveyed to the first tower 7. A third portion of the crude gas passes through a valve 12 to the adsorption tower 7 either directly or through a compressor working at a lower pressure than the compressor 2; in the latter case the outlet valves from the tower 7 are partially closed so as to maintain the pressure. This uncooled gas serves to regulate the temperature in the tower 7. From the adsorption tower 7 the gas passes to a fan 10 and storage vessel 11. In the regeneration stage, gas is circulated by a fan 17 through a heater 21, the adsorption tower 7', a water cooler 26<1>, and the condenser 27<1> cooled by expansion of gas as above referred to. A valve 25<1> is provided in series with the coolers 26<1>, 27<1> and another valve 29<1> controls a by-pass to the coolers. For rapid heating of the tower 7<1> the valve 29<1> is opened and the valve 25<1> is nearly closed. When regeneration is complete, the adsorbtion tower 7' may be cooled by closing valve 29<1> and cutting the heater 21 out of the circuit by means of valves 19, 20. After this cooling the tower 7' is again ready for adsorption. One or more traps may be provided for water or volatile substances condensing from the crude gas after compressing and cooling. It is stated that the cooling of the condenser 27<1> is enhanced by re-evaporation of volatile hydrocarbons condensing from the crude gas in the coil 14<1>. In another example, four adsorption towers are employed in rotation, two being connected in series as regards the crude gas, while a third is being cooled by circulation of gas through a fall and additional water-cooler, and the fourth tower is treated for removal of adsorbed material by means of an arrangement of a fan, a heater, coolers, and by-pass valves analogous to the parts 17, 21, 26<1>, 27<1>, &c. shown. in Fig. 1. The triple flow of the crude gas through the compressor, cooling coils, and direct path to the towers is also analogous to that described with reference to the first form. When only three adsorption towers are provided, each is subjected in turn to adsorbing, heating, and cooling steps. Additional cooling may be effected by means of a part of the treated gas in which a water spray has been evaporated.