DE1025837B - Fluidized bed process with reciprocal conveyance of solid particles in a fluidized state between two reaction vessels or a reaction vessel and a regenerator and device for carrying out the process - Google Patents

Description

GERMAN

The invention relates to a method and a device for circulating fluidized solid particles and their promotion in the state of a relatively dense solid suspension between two containers in a cycle process.

In fluidized bed processes, solid particles of small grain size are formed by an upwardly flowing Gas suspended in a reaction vessel to form a relatively dense fluidized bed in order to to form a fluidized bed of relatively high density solid particles. The fluidized bed if it does not fill the entire container, it has a clearly defined surface a liquid level above which some particles are usually entrained by the rising gas a thinned layer of relatively low solids concentration form.

The fluidized bed technology is particularly advantageous in those processes in which the solid particles conveyed back and forth between reaction vessels continuously or according to a cycle v / earths, which are subjected to different pressure and reaction conditions. The purpose the conveyance of solid particles from one vessel to the other and back is often a matter of heat the particles in a container in order to then heat the fluidized solid suspension in transfer the other container. In other cases, especially in the catalytic cracking process with Fluidized bed, catalyst particles are transferred from a reactor to a regenerator, in which the activity of the Catalyst is recovered, and then conveyed back to the reactor. In still other procedures the fluidized solid particles can form a substance that reacts during of the company has to be used up and refilled.

The driving force for the circulation of the finely divided solid particles between the two containers usually forms the "hydrostatic" pressure, which is fluidized by a relatively dense one Solid particle column is generated in a standpipe. The particles are from the bottom of the Standpipe withdrawn into a conveying gas, in which it is in the form of a dilute suspension of low density be conveyed upwards into the other container. The speed at which the fluidized particles withdrawn from the standpipe is usually done by attached to the bottom of the standpipe Regulated slide valves.

The driving force available to move the solid particles from one container to another is limited in the common fluidized bed processes. An extension of the standpipe for elevation the driving force generally requires one

Fluidized bed process

with mutual funding

of solid particles

in a fluidized state

between two reaction vessels

or a reaction vessel

and a regenerator

and device for implementation

of the procedure

Applicant:

GuIf Research & Development Company, Pittsburgh, Pa. (V. St. A.)

Representative: Dr.-Ing. B. Bloch, patent attorney,
Berlin-Wilmersdorf, Ballenstedter Str. 17

Claimed priority:
V. St. v. America December 29, 1053

Joel Herman Hirsch and Jerry McAfee,

Oakmont, Pa. (V. St. A.),
have been named as inventors

Arrangement of the device at a considerable height above the ground in order to really get the driving force noticeably increase. An increase in the driving force by increasing the density of the fluidized solids in the standpipe is also limited. Usually a swirl gas is placed at the bottom of the standpipe introduced to maintain the fluidized bed, which naturally increases the density of the fluidized Reduced suspension in the standpipe. Attempts to use what is available for conveying fluidized solid particles Driving force by means of mechanical conveying devices, such as screws or screw conveyors, increase is due to the wear and tear of the mechanical conveyors and the very large conveyors required not been very successful.

The limited driving force available for conveying the particles has a strong one Limitation of the permissible operating conditions in many fluidized bed processes result. One at times Disturbance of the operating conditions in a reaction vessel can be sufficient to

709 909/378

layer results in an excessively long contact time of the hydrocarbons with the catalyst particles excessive cracking of the hydrocarbons to reduce the yield 5 due to the formation of very large amounts of coke and gas. For explanation, below is an example Embodiment of the invention as applied to the hydrodesulfurization of residual petroleum oils described.

In Fig. 1, a reactor consisting of two reaction vessels 10 a and 10 b is shown. The two reaction vessels are arranged parallel to one another with regard to the flow of the reactants and the catalyst; they are similar units and

open with their upper end into a vessel 16 of relatively large diameter, the construction of which a load corresponding to the operating pressures of the reactors 10a and 10 & permits.

Inside the vessel 16 is a separator 18 at its upper end for the separation of entrained Catalyst particles attached from the gaseous reaction products, which is immediately associated with an ab-

processing of solid particles and entrained gases in processes and arrangements that are not for a flow reversal are intended to reverse. In some cases a reversal of the Lead to the formation of explosive gas mixtures in one or both reaction vessels.

The invention now relates to a fluidized bed process and a device suitable therefor, in which
fluidized, suspended in a first reaction gas
Solid particles in a relatively dense vortex 10
layer continuously from one vessel through one
Reaction container are circulated and back into the vessel in which the first reaction gases
are separated from the solid particles. As a result of the parallel connection, the conveyance of the fluidized solid particles from the 15 corresponds to a one vessel in a second reaction vessel or a umpteenth reaction vessel of larger diameter. In a regenerator, in which the solid particles are suspended in some cases, for example at high pressures, the second reaction gas is carried out through reactions, the structural change in the direction of the pressure difference can be achieved by using several small reactances between the vessel and the second reaction - 20 gates achieved instead of a single reactor with a large through-tank, so that a circulating current is created between the knife or, instead of the two reactors shown, two reaction tanks. be simplified.

Fig. 1 is a schematic flow diagram of a process Each of the two reactors 10 α and 10 b is on

driving for hydrodesulfurization of petroleum back its lower end with a feed line 12 standing oils according to one embodiment of the invention and at its upper end with a discharge manure; line 14 provided. The discharge lines 14

Figure 2 is a schematic flow diagram according to another embodiment of the invention.

The invention can be used in fluidized bed processes in which solid particles
Circulating current from a reaction vessel into a
others are convicted, regardless of whether
the solid particles serve as reactants, as catalysts or only as heat carriers. The method according to the invention is particularly applicable to duct 20 communicating through which the actions under high pressures are significant. In the case of reaction products from the vessel 16 in a very small number of high-pressure processes, the pressure difference shown in the extraction or processing system between the two containers will only be drawn off to a very small extent. The separated catalyst percentage of the total pressure in the container particles will advance down into one in the vessel 16. Changes in the total pressure in a 4 ° lying fluidized bed of relatively high density of the reaction vessel by a very small percentage are fed back through a dip tube 21, which then extends downwards from the percentage of the lower end of the separator 18, the pressure difference between the two vessels A pressure control valve 22 in the discharge line 20 sequence and make a sufficiently precise regulation allows a regulation of the flow velocities of the flow velocities between the two 45 speed through this pipeline and thus a Rege-container difficult. development of the pressure in the vessel 16 and in the reactors

The solid particles of the fluidized bed can be 10 α and 10 b.

typically up to a particle size of 1000 microns. From the bottom of the vessel 16 there is a stand. It is usually up to 200 microns. Down the pipe 24, in which the circulation particles, for example either as finely milled 5 ° through the reactors 10 a and 10 & coming catalylene powder or in the form of microscopic satellite particles, collect. A catalyst circulation tube spheres may be present within the 26 connecting the lower end of the standpipe 24 with the reaction vessel by means of ascending reaction - the lower end of the feed lines 12. The or fluidizing gases to a relatively tight circulation tube 26 is suspended in the vicinity of its lower end and in the fluidized bed Disabled state 55 divided into two arms marked 26 α and 26 b , the deposition held. The density of the compact we- to introduce the catalyst into the reactor belschicht can vary within wide limits, they serve 10 α or 10 b. The slide 28 α and 28 b depends on the flow rate of the vortex equip the control of the flow rate gases and the specific gravity of the fluidized catalyst particles used by the two solid particles. For fluidized bed Krackkata- 60 arms 26 α and 26 b.

lysatonen, the density of the compact eddies in the lower ends of the two supply layers is usually in the range between 240 and 560 kg / cbm. Lines 12 opens into a line 30 for supply The invention is particularly useful for processes involving the charging of residual hydrocarbon oils, suitable in which a fluidized bed is more constant through which the back height to be hydrodesulfurized it is asked for. In some processes, 65 standing oils are introduced into the device. One an excessive contact time with the catalyst hydrogen supply line 32 also terminates in the fluidized bed to a reduction in the output in the lower ends of the two supply lines booty, to favor undesired secondary 12. The turbulence of the fluidized catalyst reactions or both. In the case of the catalytic particles in the circulation line 26 and in the standpipe Cracking of hydrocarbons in a vortex 70 24 is achieved by introducing a fluidizing gas,

preferably of hydrogen, through the pipelines 34 α, 346 and 36 reached.

The vessel 16 is equipped with a second standpipe 38, which is used to collect and receive Catalyst particles are used, which are transferred into a second reaction vessel serving as a regenerator 40 should be. The regenerator 40 is at its lower end for introducing an oxygen-containing one Gas with a supply line 42 and at its upper end with a discharge line 44 provided for the exhaust gases. A pressure regulating valve 46 in the exhaust line 44 regulates the flow rate of the exhaust gas through the exhaust line and thus the pressure in the regenerator 40.

The pressure control valve 46 is actuated by a pressure difference regulator 47, which through a line 49 is connected to the vessel 16 and through a line 51 to the regenerator 40 to the pressure difference between the regenerator 40 and the vessel 16 to regulate. The pressure differential controller 47 is in turn operated by a timer 48 to control the direction of the pressure differential.

A separator 50 is fitted in the regenerator 40, the outlet side of which connects directly to the exhaust pipe 44 is connected. A dip tube 52 extends downward from the lower end of the separator 50 in a relatively dense fluidized bed in the regenerator 40, in order to be separated from the exhaust gases flowing off To recirculate catalyst particles. The regenerator 40 can be provided with an insert 53 through which the catalyst particles discharged from the regenerator flow off.

During the operation of the arrangement shown, a relatively dense fluidized bed is created of solid particles in the lower region of both regenerator 40 and vessel 16. The normal upper boundary surface of the fluidized bed in the regenerator 40 is 54, which in the Vessel 16 denoted by 56.

From the lower end of the insert 53 in the regenerator 40, a first conveying pipe 58 leads to the vessel 16. The Conveyor pipe 56 preferably opens into the vessel 16 below the upper level 56 of the fluidized bed. A slide 60 in the delivery pipe 58 in the vicinity of the regenerator 40 allows complete shut-off of the delivery pipe 58. A second delivery pipe 59 extends from the lower end of the standpipe 38 of the Vessel 16 to the regenerator 40 and opens into the fluidized bed in the regenerator. A slide 62 in Conveyor pipe 59 allows this pipe connection to be completely closed.

In addition to the valve 60, a pipe 64 for supplying fluidizing gas opens into the first conveying pipe 58, while a similar fluidizing gas line 66 opens into the second conveying pipe 59 next to the valve 62. The fluidizing gas lines 64 and 66 are equipped with control valves 68 and 70, respectively, to control the flow of the To regulate vortex gas in the delivery tubes 58 and 59. Both the sliders 60, 62, 68 and 70 as well the pressure differential controller 47 are connected to the timer 48 and are controlled by this according to the desired Operation plan actuated to determine the speed and direction of flow of fluidized To regulate solid particles between the vessel 16 and the regenerator 40.

During operation, fluidized beds are relatively high in the vessel 16 and in the regenerator 40 high density from any hydrogenation catalyst suitable for the hydrogenation of petroleum hydrocarbons maintain. The catalyst particles should generally have a diameter of up to up to 1000 microns, most conveniently up to 200 microns.

A residual oil, either alone or mixed with other feeds, such as fuel oil, is introduced into the feed lines 12 through the pipeline 30, where it is mixed with catalyst particles from the circulation line 26 and with hydrogen from the pipeline 32. Any raw material suitable for hydrodesulfurization can be used as the feed, for example a crude oil, a topped crude oil or a gas oil. Despite the high boiling point of the residual hydrocarbons, the high catalyst-oil ratio, the high temperature and the presence of hydrogen, a fluidized bed of relatively high density is formed, which flows through the supply lines 12, the reactors 10 a and 10 b and the discharge pipes 14 flows upwards. The relatively compact suspension of reaction products and catalyst particles overflows from the discharge lines 14 into the vessel 16, the diameter of which is sufficient for the gaseous reaction products to separate from the catalyst particles. The reaction products continue to sweep up through the separator 18, in which entrained catalyst particles are separated, and then through the discharge line 20 and the valve 22 to product preparation or storage facilities, not shown. The catalyst separated from the reaction products in the vessel 16 falls into the fluidized bed of this vessel and enters the standpipe 24, from which it is continuously withdrawn and again circulated through the circulation lines 26 and the reactors 10 α and 10 b .

During hydrodesulfurization, the reactors 10a and 10 & are kept at a temperature in the range between 400 and 510 ° C., with suitable preheating of the residual oil introduced into the device and heating of the catalyst particles in the regenerator. The reactors are kept at a pressure in the range between 17.5 and 140 kg / cm ² , preferably in the range from 35 to 70 kg / cm ² . The catalyst to oil weight ratio in the reactors is maintained in the range of 10: 1 to 25: 1 and the linear velocity of the gases upwardly through the reactors is about 1.5 to 91.4 cm / sec. The hydrogen is introduced into the reactors in an amount of 175 to 3500 cbm per 1000 liters of feed.

The constant circulation of the catalyst from the vessel 16 through the reactors 10 a and 10 & leads to contamination of the catalyst by the deposition of carbon on the catalyst particles. Therefore, a portion of this catalyst is periodically transferred to the regenerator 40, in which the Carbon is burned off the catalyst particles and the catalyst is heated up as a result. That is achieved by the action of the timer 48 on the pressure differential controller 47, which opens the valve 46, in order to increase the flow through the exhaust line 44 and thereby the pressure in the regenerator 40 to lower. When the pressure in the regenerator 40 falls below the pressure in the vessel 16, the timer opens 48 the slide valve 62 and the fluidizing gas valve 70, so that catalyst particles through the second Flow delivery tube 59 into the regenerator 40. Before this period of operation, the timer 48 has the Slide valve 60 and valve 68 in gas supply line 64 are closed.

The promotion of the catalyst in the form of a relatively dense fluidized suspension from the Vessel 16 in regenerator 40 allows transfer large amounts of catalyst at low flow rates and low pressure drop. Since the slide valve 62 is usually kept wide open during delivery, none occurs significant throttling through the valve, so that the abrasion and the pressure drop in the valve are low.

The continued conveyance of catalyst particles from the vessel 16 through the conveying tubes 59 into the Regenerator 40 leads to a drop in the catalyst level in vessel 16. Since the catalyst and the re-

Catalyst flow between the vessel 16 and the regenerator follows, to which a recovery of Catalyst from the regenerator 40 into the vessel 16 is connected. The timer 48 can also respond to an Ar-5 by way of example, a flow of particles between the regenerator and the vessel at all times 16 allowed in both directions. However, it is a feature of the invention that the fluidized Catalyst parts only flow in one direction ίο between the regenerator and the vessel. It In addition to the device described, other known regulating devices for pressure control can also be used Find application.

The conveyance of particles from the vessel 16 into the reaction gases when they enter via the discharge generator is usually followed by a flow in the opposite direction, lines 14 into the vessel 16 separated from one another so that the flow of the catalyst particles is alternating and the catalyst particles enter the vortex. In some cases, however, it may be desirable to have the layer of the container falling while the reaction value is, the conveyance of the catalyst between gases flowing to the discharge line 20, changing the vessel 16 and the regenerator into several abutments of the position of the upper level 56 of the vortex- 20 cuts to subdivide, which by repeatedly opening the layer essentially has no effect on the loading and closing of the slide valves 60 or 62 without the duration of the catalyst's contact with the coals Desired amount of catalyst from 40 can be achieved. It will be appreciated that more than the vessel 16 has been fed into the regenerator 40 by the number of catalyst bursts of a transfer, the timer 48 actuates the valve 62 to interrupt the same amount of catalyst particles during a catalyst flow through the feed tube 59. Oxygen-containing gas flowing up from the supply line 42 through the regenerator and the catalyst particles flow in each case abrator 40 alternately from the regenerator 40 to the vessel 16 and adds the carbon-containing deposits and back from the vessel 16 to the Regenerator 40 generates the catalyst as a result. The Regenerator The period of operation of the timer 48 for the Um-40 is normally maintained at a temperature in reverse of the flow of the fluidized catalyst range between 425 and 700 ° C. The temperature particles depend on the permissible changes in the temperature. In this range, by diluting the operating properties or the reaction conditions, air used as the oxygen-containing gas with inert particles can be used in the reactors. These depend on gases, such as exhaust gases or steam, are controlled in turn on the type of fluidized bed process or by heat exchange, for example by means of a reaction carried out, for example on the speed of the bed in a catalytic of a suitable heat exchanger in the fluidized bed process. Contamination of the catalyst. If the reaction occurs after a certain period of time, the length of which is strongly endothermic or strongly exothermic, or if the type of device used in each case depends, the timer 48 activates the pressure differential regulator 47, the catalyst becomes largely and quickly contaminated, as in the case of catalytic crackers Control valve 46 partially closes, driving, so the working cycle will be short, and in order to immediately reduce the outflow of the exhaust gases through which there must be large total amounts of particles between the exhaust pipe 44 and thus the pressure in the 45 vessel 16 and the regenerator 40 who-regenerator 40 increase. When the pressure in speech. If the speed of the impurity generator 40 exceeds the pressure in the vessel 16, the catalyst or the heat requirement of the reaction, the timer 48 opens the slide valve 60 and this is as low as the described hydrodesulfurie fluidizing gas control valve 68 and closes the fluidizing process, the total production can to catalyst control valve 70 to fluidized catalyst particles from 50 sator between the vessel 16 and the regenerator 40 to the regenerator 40 through the insert 53 and the low and the duty cycle accordingly long. Conveying pipe 58 into the vessel 16. In the embodiment of the tile shown in FIG. 2, the device remains in this position for a period of time; The ured catalyst in the vessel 16 is sufficient, then 55 lower end of a standpipe 86, from which the valve 60 can be closed and the arrangement in the lower end of the vessel 84 is returned to the starting position. Nor- supply line 88 is connected to reactor 80, in order to occasionally introduce a purge gas into the lower end of the insert 53 through the fluidized solid particles and the standpipe 38 in order to circulate the reactor in a similar manner as in the case of the adhering substances from the catalyst particles 60 embodiment according to Fig. 1 has been described to wash out before entering the conveyor pipes. is. The vessel 84 is provided with a separator 90 for the hydrodesulfurization in the reactors 10 and α
10 b and the regeneration in the regenerator 40 takes place
without interruption, regardless of the effect
of the timer 48 to promote catalyst 65
between the vessel 16 and the regenerator 40.

The mode of operation of the timer has been described for a method in which, after promotion
of catalyst from vessel 16 into the regenerator

a period of regeneration with no fluidizing gas supplied at the same time.

Separation of solid particles from the reaction products discharged through a pipe 92 connected.

The feed processed in the process is fed through a feed line 88 Feed line 94 introduced into the reactor. The swirling of the solid particles in the standpipe 86 takes place by means of a through pipes 96 and 98

A regenerator 100 is provided at its lower end with a reaction gas supply line 102 and at its upper end with a discharge line 104 for the reaction products. A separator 106 in the regenerator 100 serves to separate entrained solid particles from the reaction products and return them to the fluidized bed in the regenerator.

The regenerator and the vessel 84 are connected by means of a conveying pipe 106 which opens into the two containers below the upper level of the solid-state fluidized beds. A baffle plate 108 is positioned in front of the opening of the conveying pipe 106 in the regenerator 100 and delimits a shaft 110 leading upwards from the opening of the conveying pipe into the regenerator. A similar baffle plate 112 forms a similar shaft 114 in the vessel 84. A fluidizing gas is introduced into the shafts 110 and 114 through pipes 116 and 118 , respectively.

The regulating device for controlling the pressure in the device is similar to that described in connection with FIG. The pressure in the vessel 84 and in the reactor 80 is regulated by means of a valve 120 in the pipeline 92. The pressure in the regenerator 100 is controlled by a valve 122 in the conduit 104 which is actuated by a pressure differential regulator 126 connected to the vessel 84 and the regenerator 100. A timer 128 in turn actuates the differential pressure controller in accordance with the desired operating schedule.

In operation, a pressure drop from vessel 84 to regenerator 100 causes fluidized solids to flow down through well 114, through conveyor tube 106 and then up through well 110 into regenerator 100. When the direction of the pressure drop is reversed under the action of the timer , the fluidized solid particles are conveyed through the conveying pipe 106 into the vessel 84. Meanwhile, fluidized solid particles are continuously circulated through the reactor 80 while keeping the contact time of solid particles and reaction gases constant. The reversal of the direction of the pressure gradient and its regulation are achieved by the action of the timer and the pressure difference regulator 126.

Some of the solid particles used in the reaction can also be placed in a separate reaction vessel for treatment with other reaction gases and back again. The Ver- drive enables a high pressure difference to be achieved to promote the catalyst particles in the or from the second reaction vessel while avoiding the disadvantages associated with the application very long standpipes or mechanical solids handling devices are connected.

Claims (5)

Claims: 60 1. Fluidized bed process with reciprocal promotion of solid particles in a fluidized state between two reaction vessels or a reaction vessel and a regenerator while keeping the fluidized bed height constant in the reaction vessels, characterized in that the solid particles are continuously circulated from the reaction vessel (10 a, 10 b, 80) through an intermediate vessel (16, 84) under the same pressure with downwardly leading connecting pipes (24, 26) are circulated back into the first reaction vessel and the conveyance of solid particles from the circulation system into the second vessel (40, 100) and back through one or two Pipelines (58, 59) which connect the vessel (16, 84) to the second container, the direction and flow rate of the fluidized particles being controlled by regulating the pressure in the second container. 2. The method according to claim 1, characterized in that the delivery and return between the vessel (16, 84) and the second container (40, 100) takes place through two separate pipes, each provided with a shut-off valve, at the same time as the pressure increase in the second Container the valve in the line for the flow from the second container into the vessel is automatically opened and the valve in the opposite line is closed and the valves are automatically reversed when the pressure drops. 3. The method according to claim 1, characterized in that the pressure in the circulation system from the first reaction vessel (10 a, 10 b, 80), vessel (16, 84) and standpipe (24, 26) kept constant during all operating periods and the promotion exclusively 'Is regulated by changing the pressure in the second container (40, 100). 4. Apparatus for performing the method according to claim 1 with two reaction vessels and an automatically operating control device composed of a timer and differential pressure regulator for regulating the pressure gradient between the two reaction vessels, characterized in that the upper end of the first reaction vessel (10 1) between. 80) with a separating vessel (16 or 84) of relatively large diameter and a standpipe (24, 26 or 86) leading down from the bottom of the vessel are connected to the lower end of the reaction vessel to form a circle, which is connected to a pipeline at the foot of the standpipe (30, 32 or 94) for supplying the reactants and equipped at the top of the vessel with a valve-controlled pipeline (20 or 92) for withdrawing the reaction products and the vessel (16 or 84) via a delivery line (58, 59 or 106) is connected to the second reaction container (40 or 100), the gas discharge line (44 or 104) of which is also equipped with a valve, the pressure differential regulator (47 or 12) alternating the valve in the exhaust line of the second reaction container Actuated increase or decrease in the pressure in the second reaction vessel above or below the pressure in the first reaction vessel. 5. Apparatus according to claim 4, characterized in that the delivery line between the Vessel (16) and the second reaction vessel (40) are two provided with valves (60 and 62) Pipelines (58 and 59) consists of which the conveyance from the vessel to the second reaction vessel serving pipe (59) is connected to a second shortened standpipe (38) of the vessel, while the return line (58) directly from the fluidized bed of the second reaction vessel leads into the fluidized bed of the vessel, and the pressure differential regulator except with the valve (46) in the exhaust pipe of the 709 909/373 second reaction vessel is also in working connection with these valves (60 and 62) and this depending on the pressure vessel between the two reaction vessels operated in such a way that when the pressure in the second reaction vessel increases, the return line (58) and the line are opened (59) closed, when the pressure drops below the pressure of the vessel, the line (59) opens and the line (58) is closed. References considered: U.S. Patent Nos. 2,581,670, 2,601,676. A priority document was displayed when the registration was announced. 1 sheet of drawings