Abstract: An early meltdown process of wax sweating is provided which enhances the efficiency, quality, product yield, and throughput of wax. In the early meltdown process, slack wax is crystallized. The crystallized wax is then sweated while simultaneously draining the liquid drippings from the sweating oven. The congealing point of the liquid drippings are monitored. When the congealing point of the liquid drippings indicate that the melting temperature of the desired wax product has been obtained, sweating and drainage are stopped, and the remaining solid bed of wax in the sweating oven is rapidly melted and subsequently upgraded.

Abstract: An apparatus for the catalytic cracking of hydrocarbon feedstocks with reaction temperature control is provided which includes an upward-flow or downward-flow cracking column, means for feeding said column under pressure with a hydrocarbon feedstock and with particles of a regenerated cracking catalyst, at least one means for injection of an auxiliary fluid downstream of the zone in said column where the hydrocarbon feedstock and the regenerated catalyst particles are contacted with each other, to reduce the temperature of the reaction zone situated directly downstream thereof, means for separating the products of the cracked feedstock and the spent catalyst particles, at least one stripping means, at least one unit for regeneration of the catalyst by combustion of the coke deposited thereon and means for recycling the regenerated catalyst to said feeding means.

Abstract: A process is disclosed for controlling movement of a vertically movable plug valve with respect to a bottom open end of a riser conduit of a catalytic conversion apparatus during startup and shutdown. The method involves sensing the pressure between the communicating surfaces of the plug valve and the riser conduit as the riser conduit expands or contracts due to thermal changes experienced during startup and shutdown. When the riser conduit expands and causes the pressure to exceed a preselected range, the position of the plug valve with respect to the riser conduit is lowered to reduce the pressure to within the range. When the riser conduit contracts and causes the pressure to fall below the preselected range, the position of the plug valve with respect to the riser conduit is raised to prevent catalyst flow through the valve.

Abstract: A computer system for a zone fired furnace generates a plurality of temperature set point signals for a plurality of furnace zones. The set point signals are derived from a master controller acting on the measured temperature of fluid that is heated in the plurality of furnace zones and then combined to form a heated stream. The master signal, which is a velocity type signal, is provided to a plurality of zone control stations corresponding to the plurality of furnace zones. Each zone control station integrates the master signal, and then biases the master signal for use as a zone temperature set point. The zone control station can be used to bias the individual coils so as to balance the temperature of the coils with respect to each other, or to intentionally unbalance one or more coils, as desired, so as to improve furnace operations.

Abstract: An improved method for producing a hydrotreated oil from a naphthenic feed is described. The process comprises passing the naphthenic feed through the multistage hydrotreating process with intermediate removal of hydrogen sulfide and/or ammonia.

Abstract: A cooling fluid is utilized to withdraw heat from a KOH treater. The passing of the cooling fluid in heat exchange with the KOH treater is controlled so as to maintain desired operating pressures and also substantially maximize heat transfer. Bypassing of the feed around the KOH treater is utilized only if sufficient cooling cannot be provided to prevent a temperature runaway.

Abstract: A countercurrent technique is disclosed for contacting liquid and gas reactants in a fixed porous catalyst bed. The reactants are maintained as a multiphase mixture in the catalyst bed. Upwardly flowing dispersed gas is disengaged from liquid feedstock above the catalyst bed, while controlling froth level.

Abstract: An effective, efficient and safe method is provided to accurately determine the amount of catalyst in an ebullated bed reactor without depressurizing the reactor or exposing the hydrocarbon in the reactors to oxidizing, flammable, or explosive conditions. Measurements are made automatically by density detectors and pressure sensors along with other equipment.

Abstract: A temperature control process is disclosed for a hydrocarbon conversion process wherein a feedstock is heated in a furnace and is partly converting in a first reactor, the effluent from the first reactor is cooled in a first heat exchanger and by adding a quench, then the cooled effluent is converted in a second reactor, and the effluent from the second reactor is cooled in a second heat exchanger. Part of the pre-furnace feedstock is used as coolant for the two heat exchangers, the amount of coolant being controlled by a first bypass valve for a line bypassing both heat exchangers and by a second bypass valve for a line bypassing only the second heat exchanger. The inlet temperature for the second reactor is controlled while maximizing the pre-furnace feedstock temperature by adjusting the valve for quench and the two bypass valves.

Abstract: In a fractional distillation process, the operation of a reflux pump in the process is enhanced by providing that liquid discharged from the reflux pump is returned directly to the reflux pump suction during the periods when the liquid reflux supply from the fractional distillation process is not sufficient to keep the reflux pump in constant operation.

Abstract: A system for automatically levelling a vehicle, such as a recreational vehicle, relative to gravity includes a plurality of extensible jacks, preferably hydraulic, disposed at strategic positions on the vehicle underside. Switches sense the downward tilting of the vehicle relative to gravity at the strategic positions and produce signals to operate the jacks in accordance with such tilting. Before the jacks are extended, air bags in the vehicle are deflated. When the hydraulic pressure in a hydraulic circuit exceeds a first value, the jacks are extended in a particular sequence depending upon the particular directions in which the vehicle is tilted relative to gravity. A delay is preferably provided between the operations of each jack and the next jack in the sequence to eliminate transients in the next jack operation. When the vehicle has been levelled, jacks not previously extended are extended until they engage the ground with a second pressure less than the first pressure.

Abstract: A computer control system for automatically optimizing the temperature of the feed supplied to a distillation column from a fuel fired preheat furnace, wherein the furnace temperature is manipulated in response to a measured ratio of distillate flow (D) from the tower to fuel flow (F) to the furnace. The D/F ratio is maximized by periodically comparing the present value of D/F to the previous value and incrementally increasing the furnace temperature as long as the D/F ratio increases. When no change is detected or the D/F ratio starts to decrease the furnace temperature is incrementally decreased until the D/F ratio again increases and reverses the control action once more.

Abstract: A method of feeding a mixture of fluidized solids, such as cracking catalyst, and a fluidized feed material to be contacted therewith, such as a hydrocarbon feedstock to be cracked, into a contacting zone. In another aspect, method and apparatus useful in starting up a catalytic cracking unit are disclosed.

Abstract: Cut point is controlled in a distillation process by monitoring the partial pressure in a stripper.

Abstract: For parallel heat exchangers, one using a more preferred heat exchange medium as a heat exchange source and another using a less preferred heat exchange medium, maximum use of the more preferred heat exchange medium is used prior to use of the less preferred heat exchange medium in achieving a desired total heat exchange through the parallel heat exchange system. In employing such a heat exchange system in a cracking process it is combined with individual control of flows of feed fluid and diluent fluid to a plurality of individual cracking tubes in a cracking furnace to maintain a desired mass flow of feed fluid and ratio of mass diluent fluid to steam fluid to each such cracking tube.

Abstract: An improved distillation process and apparatus are provided whereby liquid product recovery other than bottom product is maximized and feed stream heating is minimized. Inert gas streams combined with the feed stream and introduced into the distillation tower are controlled whereby feed stream heater residence time and partial pressures of feed stream components are minimized. The temperature of the combined inert gas-feed stream exiting the feed stream heater is controlled at a minimum temperature by establishing signals representative of overflash, bottom product specification and other conditions and comparing such signals whereby the signal which represents the lowest heater outlet temperature is utilized for controlling the heater operation.

Abstract: Temperature is controlled in a hydrogenation reactor without changing the flow rate of feed into the reactor to maintain a pre-determined temperature in the reactor. In one embodiment, the firing rate of a fuel fired furnace for heating feed to the reactor is controlled in response to the temperature sensed in the reactor to maintain a pre-determined temperature. In another embodiment, the flow rate of a quenching stream for cooling feed to the reactor is controlled in response to temperature sensed in the reactor to maintain a pre-determined temperature in the reactor.

Abstract: A delayed coker control system wherein the hydrocarbon feed flows to the coker furnace is automatically limited to the lowest of the maximum allowable flows to avoid furnace zone flooding, an air-limited furnace and overfilling of the coke drum in the cycle time. Flows among the separate furance zones are adjusted to balance heat loads on each stream and to redistribute excess flow to non-flooding zones.

Abstract: In an expanded bed reactor, the expansion of the bed is automatically controlled by automatically changing the rate of speed of a recycle pump for the reactor. The bed is preferably provided with both high and low level bed detectors, and a further detector for determining abnormally high levels.

Abstract: A continuous process and system is provided for a petroleum oil in a multi-phase fixed bed catalytic reactor column comprising methods and means for:feeding the oil and a reactant gas at production flow rates above a first bed of porous solid catalyst particles under conversion conditions for cocurrent downward flow therethrough, collecting and withdrawing the treated oil from the first bed and redistributing at least a portion of the treated oil to at least one succeeding catalyst bed while permitting the gaseous phase to flow directly to the succeeding lower catalyst bed, recycling a quantity of treated oil collected below a catalyst bed and reapplying the treated oil at a preceding redistribution zone above the bed from which treated oil is collected, whereby the total of oil production flow rate and recycled treated oil flow rate is maintained at a predetermined minimum sufficient to effect uniform catalyst wetting. This technique is useful for hydrodewaxing of oils over zeolite catalysts.

Abstract: A method and apparatus for passivating the adverse catalytic effects of metal contaminated hydrocarbon feedstocks is described. The method is directed at the use of control means to regulate the residence time of the catalyst in the passivation zone and to regulate the reducing gas flow rate to the passivation zone.

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: Disclosed is a method and apparatus for feeding catalyst, oil and steam into a fluid catalytic cracking (FCC) riser. Oil passes through respective oil lines into a multiplicity of upwardly extending nozzles located at a lower portion of the riser, while steam passes through respective steam lines into the nozzles where it blends with the oil, with the combined oil and steam mixture being fed through the nozzles into the riser. Each oil line and steam line is provided with a valve to separately control oil and steam flow rates, respectively, in each of the nozzles to obtain a substantially constant catalyst to oil ratio across a horizontal cross-section of the riser. The substantially constant catalyst to oil ratio is represented by a substantially isothermal temperature profile across the horizontal riser cross-section, which is detected by measuring the temperature at various points along the horizontal cross-section.

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: In a two-stage hydrofining process, hydrogen is utilized as a quench fluid to reduce the temperature of the effluent withdrawn from the hydrodemetallization stage prior to providing such effluent to the hydrodesulfurization stage and the flow of such hydrogen is controlled so as to maintain a desired temperature for the feed to the hydrodesulfurization stage. Also, the flow of fuel to a furnace is controlled so as to maintain a desired temperature for the feed to the hydrodemetallization stage and hydrogen flow rates are manipulated throughout the process so as to maintain desired hydrogen concentrations throughout the hydrofining process.

Abstract: The temperature of a crude oil provided from a crude oil preheat furnace to a crude tower is substantially minimized by controlling such temperature so as to maintain a desired minimum overflash flow in the crude tower. Also, the temperature of each of the individual coils in the preheat furnace are balanced with respect to each other. Such minimization and balancing results in substantially optimal utilization of the fuel provided to the preheat furnace which results in considerable economic savings with respect to the operation of the preheat furnace.

Abstract: Method of operation for a continuous countercurrent extraction zone, to which a charge mixture stream and a solvent stream are continuously supplied and from which an extract stream and a raffinate stream are continuously withdrawn. In one embodiment, the method comprises establishing a recycle stream consisting of a portion of the light phase stream withdrawn from the column, combining the recycle stream with the charge mixture stream, and controlling the streams flowing to and from the column. The combined feed stream to the extraction zone is controlled at a constant flow rate and recycle flow has preference over charge mixture flow, thereby causing charge stream flow to vary inversely with recycle flow. An important feature of the invention resides in adjustment of composition of this total combined feed stream to the extraction zone in order to deal with fluctuations in other parameters.

Abstract: The Reid Vapor Pressure of a hydrocarbon mixture consisting essentially of hydrocarbons selected from the same series is determined based on the actual temperature and vapor pressure of the hydrocarbon mixture. The thus determined Reid Vapor Pressure may be compared to a set point for the Reid Vapor Pressure with the results of the comparison being utilized to maintain the actual Reid Vapor Pressure substantially equal to the desired Reid Vapor Pressure.

Abstract: A process and apparatus for the cooling of hot fluidized solid particles such as catalyst of an FCC petroleum refining process. The particles flow downward from a first dense phase fluidized bed into a cooling chamber and contact the shell side of a vertically oriented shell and tube heat exchanger where cooling occurs via indirect heat exchange with a cooling medium circulating in the tubes. The extent of cooling is controlled by the varying of the heat transfer coefficient between the tubes and particles in the heat exchanger. The coefficient is varied by changing the quantity of fluidizing gas fed to the fluidized bed in the heat exchanger. The heat exchanger is located within a lower portion of the cooling chamber totally below the particle inlet and outlet conduits. The heat exchanger can therefore be removed from service and protected by being buried under unfluidized relatively cool catalyst. The fluidizing gas supports combustion within a lower combustion zone.

Abstract: Method and apparatus are provided for maintaining a substantially continuous gas flow through particulate solids in two zones. The solids are moved from a low pressure zone to a high pressure zone by means of a valveless lock hopper system. Maintenance of gas flow while simultaneously transferring particles between zones is accomplished without the use of moving equipment such as valves. The invention is particularly applicable in the regeneration of catalyst used in hydrocarbon conversion processes such as catalytic reforming.

Abstract: A technique, including an apparatus, for automatically regenerating a catalyst used in a process for obtaining a product in an exit stream from a raw material in a feed stream of a reactor, comprises determining the concentration of raw material in the feed and exit stream and obtaining a value for the catalyst selectivity as a function of the difference between the concentrations. When a selected selectivity is reached, which is indicative of the need for the catalyst to be regenerated, regenerator equipment is activated for regenerating the catalyst in the reactor. To continue the process, the feed stream is transferred to an auxiliary reactor during regeneration of the primary reactor, which contains regenerated or fresh catalyst.

Abstract: A desired separation between sidedraw product streams withdrawn from a fractional distillation column is maintained by controlling the flow rate of the external reflux associated with a particular sidedraw product stream in response to the output signal from a temperature controller which is reset by an internal reflux controller. Such cascade control improves the stability of a fractionation process and provides for good control of the separation between sidedraw product streams.

Abstract: In a fractional distillation process in which a sidedraw product stream is withdrawn from the fractional distillation column, the flow rate of the overhead product stream is controlled so as to increase the flow of the upper external reflux so as to drop as much as possible of the overhead product into the sidedraw product stream. However, valve position control is utilized to override the control of the flow of the overhead product stream, which is being controlled so as to substantially maximize the flow of the sidedraw product stream, if the valve controlling the flow of the upper external reflux approaches fully open such that control of the liquid level in the overhead accumulator associated with the fractional distillation process is not lost.

Abstract: There is disclosed a system for measuring and controlling the concentration of hydrogen in hydrogen recycle processes used in oil refineries and petrochemical plants. The system is intended to reduce the amount of hydrogen and hydrocarbon vapor circulating in such systems, thus reducing the quantity of utilities needed to operate such systems. Specifically, there is a savings of compressor power and fuel required for heating. The system is dependent on the recognition that a decrease in cooling medium temperature results in an increase in hydrogen flow, which can be decreased to the minimum permissible without endangering catalyst activity and stability and product yield if hydrogen concentration is monitored, and that partial pressure is the key parameter.

Abstract: A method for decreasing the external energy input to a fractionation system is disclosed. The method utilizes a compression zone communicating with either the overhead fraction or the bottoms fraction from a fractionation zone. The method is directed at regulating the rate of energy addition and/or removal to the fractionation zone by at least one of the fractions returned to the fractionation zone to maintain the separated fractions within the desired limits.

Abstract: Process and apparatus are provided for the recovery of low, medium and high boiling components from feed streams containing same wherein reboiler fouling, gumming and the like are minimized, via the control of fractionator reboiler temperatures.

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: 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: There is disclosed a system for measuring and controlling the concentration of hydrogen in hydrogen recycle processes used in oil refineries and petrochemical plants. The system is intended to permit reduction in hydrogen use in hydrogen-consuming hydrogen recycle processes. The system is dependent on the recognition that a decrease in cooling medium temperature results in an increase in vent gas flow, which can be decreased to the minimum permissible without endangering catalyst activity and stability and product yield if hydrogen concentration is monitored, and that partial pressure is the key parameter.

Abstract: Spent catalyst is continuously regenerated in a fluid catalytic cracking system by forcing air to flow through such a catalyst bed to burn carbonaceous material from it and to heat such catalyst for fluid catalytic contact with a hydrocarbon feed stream in a reactor transfer line or riser.The combustion of carbonaceous material is optimized by controlling the rate of air flow through the bed, supported on an open grid having openings which are substantially larger than the average diameter of the catalyst particles. This assures even air flow throughout the bed. Such air flow is optimized by collecting catalyst that may backflow under low flow conditions from below one of the lowest grid openings. The particles are withdrawn from a collector in a minor portion of the air flowing to the catalyst bed. The presence of catalyst is detected either by direct observation or by temperature measurement.

Abstract: A method for improving fluidization of a particulate material flowing through a fluid conductor is provided by controlling the rate of addition of fluid, such as aerating gas or steam at a plurality of spaced apart locations along the conduit. The composition and rate of flow of the fluidized particles, is controlled by positioning a source of penetrative radiation such as neutrons, gamma rays, or X-rays at any location along the conduit so that the radiation traverses the fluidized particulate material flowing therein. A radiation detector is positioned opposite the source so that radiation absorbed in the conduit by the fluidized mixture may be measured as an electrical quantity. This electrical quantity may represent the total number of gamma rays of a preselected energy interacting with a detector in a given time interval or the average number of all gamma rays generating electrical pulses by interaction with the radiation detector.

Abstract: In a fractional distillation process in which a compressor is used to supply heat to the fractional distillation process, a plurality of signals representative of a plurality of speeds of the compressor, required to prevent various process constraints from being violated or maintain various desired process oprating conditions respectively, are compared. The signal representative of the highest compressor speed is utilized to control the compressor. In this manner, the compressor is run at the minimum speed required to satisfy the various process constraints and maintain the desired process operating conditions.

Abstract: A process vessel which contains a control system for maintaining average pressure drop across gas discharge nozzles above a minimum valve to prevent the occurrence of inactive nozzles, said nozzles comprising part of a distributor which is used to distribute gas across the lower portion of the processing vessel, wherein the control system comprises:(a) means for establishing a flow signal representative of the rate of flow of gas in said pipeline supplying the gas to said distributor;(b) means for establishing a temperature signal representative of the temperature of the gas flowing in said distributor;(c) means for establishing a pressure signal representative of the pressure of the gas flowing in said distributor;(d) computing means for calculating the average pressure drop across said nozzles using said flow, pressure, and temperature signals and appropriate constant parameters and equations;(e) means for comparing said average pressure drop across said nozzles with a minimum value, generating a correction

Abstract: A fractional distillation process, in which the flow rate of the external reflux is utilized to control the bottoms product composition, is controlled so as to maintain a desired bottoms product composition to the extent that maintaining the desired bottoms product composition does not cause a process constraint to be violated. A plurality of actual process conditions are compared to process constraints for those process conditions to determine if the flow rate of the external reflux should remain the same, be increased by an incremental amount or be decreased by an incremental amount. The order of the comparison of process constraints to actual process conditions is such that the most important comparison will control the external reflux flow rate if that comparison indicates that a process constraint has been violated.

Abstract: A desired cloud point temperature for a side draw product stream from a fractional distillation column is maintained at a desired level by comparing a calculated actual cloud point temperature, which is updated periodically by a cloud point measurement, to a desired cloud point temperature with results of the comparison being utilized to control the flow rate of the side draw product stream so as to maintain the actual cloud point temperature of the side draw product stream substantially equal to the desired cloud point temperature. Use of the calculated cloud point temperature provides a means by which continuous control of the actual cloud point temperature of the side draw product stream can be maintained.

Abstract: The heat to a feed in a distillation operation is controlled in response to the amount of liquid in a liquid condensate collection means.

Abstract: There is disclosed a system for measuring and controlling the concentration of hydrogen in hydrogen-consuming hydrogen recycle processes used in oil refineries and petrochemical plants. The system is intended to reduce utilities and hydrogen usage by means of adjusting vent gas flow and the quantity of hydrogen and hydrocarbon vapor circulating to obtain the operating parameters which yield minimum cost. Specifically there can be a savings of compressor power, fuel required for heating, and hydrogen. The system is dependent on the recognition that a decrease in cooling medium temperature results in an increase in hydrogen flow, which can be decreased to the minimum permissible without endangering catalyst activity and stability and product yield if hydrogen concentration is monitored, that partial pressure is the key parameter, and that it is advantageous to optimize.

Abstract: A control system is disclosed for modifying the flow of hydrogen in a hydrocarbonaceous apparatus wherein a charge stock and a vaporous hydrocarbon-hydrogen recycle are charged to a reaction zone to convert the hydrocarbons and produce a reaction zone effluent conduit which is cooled to provide, via a gas-liquid separation zone, a liquid hydrocarbon product stream and the vaporous hydrocarbon-hydrogen recycle stream, the latter being returned to charge stock admixture by a compressor. The control system senses the partial pressure of hydrogen, compares that value to a previously determined value and develops a signal correlative thereto, which is transmitted to a regulater that controls the quantity of vaporous hydrocarbon-hydrogen stream recycled to admixture with the charge stock. In a hydrogen consuming process, the hydrogen partial pressure is sensed downstream of the reactor while in the hydrogen producing process, the hydrogen partial pressure is sensed in the inlet to the reaction zone.

Abstract: A control system is disclosed for modifying the flow of hydrogen recycle gas to a reaction apparatus which includes the admixture of a hydrocarbon charge stock with a recycle hydrogen-hydrocarbon stream and passage of the same to a hydrocarbon reaction zone to convert the hydrocarbons to a product effluent stream that is cooled to form a separated, via a separation zone, liquid product stream (withdrawn from the process) and a vaporous hydrogen-hydrocarbon stream, which is divided into the hydrogen-hydrocarbon recycle stream and a hydrogen-hydrocarbon vent stream. The recycle stream is returned to admixture with the hydrocarbon charge stock by a compressor while the vent stream conduit, in connection with the recycle conduit, has a controllable flow restriction device.

Abstract: Where gas flows through distribution nozzles and then up through a liquid or a bed of particles contained in a processing vessel, the method and apparatus of this invention can be used to maintain a minimum average pressure drop across the nozzles, thus preventing the occurrence of inactive nozzles and the consequences thereof.