Abstract: The present invention relates to a process and an apparatus for steam cracking a mixture of hydrocarbons comprising passing steam and the mixture of hydrocarbons through at least one heated cracking tube. The process is characterised in that it is controlled by analyzing the mixture of hydrocarbons fed to the cracking tube with an infrared spectrophotometer to determine the absorbances at a number n of wavelengths in the range 0.8 to 2.6 microns and by using the results of this absorbance to determine one or more values V of steam cracking process conditions which will achieve a desired value P of the space time yield of one or more products of the steam cracking reaction.

Abstract: The rate at which an oxygen-containing gas stream is admixed with hydrocarbons and hydrogen upstream of a catalytic hydrogen oxidation zone is controlled on the basis of temperature differentials across the oxidation zone and an upstream catalytic dehydrogenation zone. This control overrides the normal control mode based upon the outlet temperature of the oxidation zone effluent stream, which is the inlet temperature to a subsequent bed of hydrocarbon conversion catalyst. The control method can be used to apply oxidative reheat technology to a variety of processes.

Abstract: A process control technique for upgrading C.sub.3 -C.sub.4 hydrocarbon feed containing olefins to produce heavier liquid hydrocarbons comprising converting a major portion of C.sub.3 -C.sub.4 olefins in an oligomerization zone by contacting a shape selective medium pore zeolite catalyst at elevated temperature and pressure to make distillate and olefinic gasoline. The oligomerization stage effluent is fractionated to provide distillate and gasoline product and a C.sub.3 -C.sub.4 intermediate stream containing isobutane and unconverted propene and butylene. The C.sub.3 -C.sub.4 intermediate stream is combined under control with a portion of C.sub.3 -C.sub.4 feed and further converting the combined streams in an alkylation zone to make heavier paraffinic hydrocarbons. The olefin feed may be produced by catalytically converting methanol or similar oxygenated hydrocarbons in a known process.

Abstract: The method is particularly adapted for controlling the molecular weight of a product output from a polybutene reactor. The method includes the steps of: deriving from the operating parameter of a polybutene reactor system a formula which correlates molecular weight as determined by product viscosity or other parameters of the product output with operating variables such as temperature of the reactor and concentration of isobutylene in the reactor, which concentration can be controlled by the amount of catalyst, e.g.

Abstract: A control system is provided for an olefins upgrading plant wherein catalytic reactor effluent is separated to recover heavy, intermediate and light hydrocarbon streams. An improved liquid recycle system includes a level control technique for diverting a portion of a separator overhead vapor stream. Recycle flow rate may be determined by reactor temperature differential in a series of adiabatic catalytic reactors.

Abstract: A reactor bed, particularly one designed for converting alcohols to gasoline, is provided with a section downstream of the catalyst bed filled with high heat capacity thermal absorptive material. When the circulation of recycled gas to the system is temporarily suspended automatic valves terminate the injection of alcohol feedstock and begin the injection of inert gases such as methane into the system, thereby avoiding the formation of a hot spot which would subsequently damage the catalyst and equipment downstream.

Abstract: The flow rate of a diluent fluid, such as steam, hydrogen or methane, to a cracking furnace is controlled so as to maintain a desired outlet velocity for the effluent flowing from the cracking furnace or to maintain a desired residence time for the feed stream in the cracking furnace. Feed forward control for the flow rate of the diluent fluid is provided by using an empirical model of the cracking furnace to predict either the outlet velocity or the residence time based on measured system parameters. Feedback control for the flow rate of the diluent fluid is provided by calculating the actual outlet velocity or actual residence time based on measured system parameters. The measured outlet velocity or residence time is utilized to bias or correct the predicted outlet velocity or residence time to provide a corrected prediction of the outlet or residence time.