GB1031717A - Improvements in and relating to the hydrogenation of hydrocarbon oils - Google Patents

Abstract

In a continuous process for the vapour phase hydrogenation of a hydrocarbon distillate oil comprising aliphatic constituents to obtain gaseous paraffinic hydrocarbons, wherein the oil vapour and a gas comprising hydrogen are continuously introduced into a thermallyinsulated reaction chamber so constructed as to define an endless path along which gas can circulate within the chamber, the oil vapour is reacted exothermically with hydrogen in the chamber at 600 DEG to 800 DEG C. at a pressure of at least 5 atmospheres gauge, gaseous products are continuously withdrawn from the chamber, the reactants are introduced in the form of at least one jet through orifice means into the reaction chamber to cause a substantial body of gas comprising reactants and products to circulate continuously around the said endless path, and the reactants are preheated to an extent such as to maintain a reaction temperature which is uniform throughout the reaction chamber except in the vicinity of the orifice means. Preferably, the reaction takes place at 700-800 DEG C. and 20 to 50 atmospheres gauge. The hydrogenating gas may be substantially wholly hydrogen but may also contain carbon monoxide or carbon dioxide, these mixtures being obtained by the reaction of coal coke or hydrocarbons with steam. The rate of deposition of carbon can be markedly decreased by incorporating steam into the hydrogenating gas, e.g. 10%. The expression "hydrocarbon distillate oils comprising aliphatic constituents" is used to refer to distillates consisting wholly or predominantly of hydrocarbons of which the aliphatic constituents are hydrocarbons or are the side chains of alkylated aromatic hydrocarbons. The term hydrocarbons includes both unsubstituted hydrocarbons and hydroxy substitution products of hydrocarbons, the hydroxyl groups of which are split off during the reaction. The hydrocarbon distillate oils may be petroleum distillates having boiling points in the range 160-360 DEG C., advantageusly light distillates having boiling points of from 70 DEG to 200 DEG C. Specified hydrocarbons are kerosene, butane, propane and coal tar distillates, e.g. creosote oils. To maintain the desired reaction temperature the oil vapour and hydrogenating gas are preheated to temperatures within the range 350 DEG to 550 DEG C. The ability of the gases to circulate in the reaction chamber is specified in terms of the recirculation ratio which is at least 3:1. The recirculation ratio is defined as the ratio of the volume of gas circulating within the reaction chamber to the volume of gas withdrawn from said chamber during one complete period of circulatory motion. In further preferred embodiments, 2 to 8 gallons of light distillate (measured as liquid distillate) are introduced with each 1000 cubic feet (measured at S.T.P.) of hydrogen in the hydrogenating gas, the temperature within the chamber, except in the vicinity of the inlet orifice is uniform to within \sB10 DEG C. and the velocity of introduction of the reactants is from 100 to 2,000 feet per second. As indicated in the Figure (not shown), hot hydrogenating gas is introduced into a reaction chamber until the temperature reaches 600 DEG C. at 25 atmospheres gauge. Oil vapour is then mixed with the hydrogenating gas and the composition of the mixture controlled to maintain the chamber temperature at 750 DEG C. The reaction gases circulate and products are taken off through an outlet. On analysis, the products contained a gaseous fraction, having 35% hydrogen, 49.3% methane, and 12.8% ethane, and a condensate containing benzene, toluene, naphthalene and higher aromatic hydrocarbons.