FI82890B - Method for maintaining essentially continuously upward directed flow during transport of solid material - Google Patents

Description

1 82890

This invention relates to the field of solids flow and process control. More specifically, it relates to the control of gas flow through zones containing solid particulate matter and to the control of the internal pressure in these zones when solid matter is transferred between zones. The specific use relates to a catalyst treatment system for use in mobile bed hydrocarbon conversion processes, including catalytic reforming.

U.S. Patent 2,851,401 is believed to be the most relevant literature reference. This patent deals with the transfer of solid particulate matter from one location to another, but does not contain any information regarding the maintenance of gas flow through said locations or the maintenance of pressures at said locations, nor does it advise the use of the gas pipes of this invention. U.S. Patent 2,851,402 provides information on solids transfer utilizing the teachings of U.S. Patent 2,851,401.

An important application of this invention relates to a catalyst used in hydrocarbon conversion processes. U.S. Patents 2,423,411, 2,531,365, 2,854,156, 2,854,161 and 2,985,324 are examples of literature references in which catalysts for a hydrocarbon process are transferred and treated.

For further information on catalytic reforming and catalyst regeneration, which is the subject of the detailed example presented herein, U.S. Patents 3,647,680 and 3,692,496 may be consulted.

There are many chemical processes where it is necessary to contact the gas and the solid particulate matter or solids or particles. Often chemical 2,82890 reactions as well as physical phenomena occur during such contact. In most cases, the gas and solids must be in contact for a certain minimum time and the desired chemical or physical reaction or change will not occur or will be incomplete if the contact time is shorter. In some cases, there is a maximum contact time beyond which suboptimal or undesirable results are obtained. It is highly desirable to perform the gas-solid contact processes in a continuous or semi-continuous manner instead of a batch operation.

The contact zone is usually maintained at some kind of contact gas overpressure (above the atmosphere). Particles must be fed in and removed from the pressurized zone without losing contact gas to the atmosphere. It is often necessary to maintain the pressure inside the contact zone at a certain value or in a certain range. The pressure in the contact zone may be higher than the zone from which the particles are fed into the contact zone. Feeding solids into the zone against high pressure causes numerous problems. When using such:. equipment other than screw conveyors or sector valves, contact between the equipment and solids breaks down solid particles by breaking them into smaller particles and causes wear of the equipment. It is difficult to maintain an effective seal to prevent escape from the contact zone and the maintenance costs of the equipment are high. These problems increase when solids or gas or both are at high temperatures. Pressure lock systems with shut-off valves through which solids pass have been the preferred method of feeding solids into the pressurized zone, but the valves are a constant subject of maintenance. The system using the valves is briefly described below.

The aforementioned U.S. Patent 2,851,401 describes problems associated with the transfer of solids and advises the transfer of solids without the use of mechanical equipment that is prone to wear or that breaks down solids. However, this patent No. 3,82890 does not address various aspects of gas flow, such as those mentioned above. Likewise, it is often desirable to maintain a constant gas flow, even when the solids flow is batch-like. The use of a continuous gas flow allows better control of the contact time and promotes the normal chemical or physical process by constantly supplying fresh gas to the solids. In some cases, it is very important to bring the incoming solids into immediate contact with the fresh gas, i.e., a gas that has not yet been in significant contact with the solids.

The present invention is useful in the implementation of numerous processes, and in particular in the implementation of hydrocarbon conversion processes, such as catalytic reforming, which is the subject of the detailed example set forth below. Another process in which this invention can be utilized is the conversion of light paraffins to light olefins. For example, this catalytic dehydrogenation process converts propane to propylene. In another catalytic hydrocarbon conversion process, light paraffins and / or olefins are processed to obtain aromatics and hydrogen. This invention is useful in regenerating the catalyst used in these processes. An example of a process other than the conversion of hydrocarbons to which this invention is applicable is the treatment of a gas stream to remove a component by contacting it with particulate solids, such as removing sulfur dioxide from a flue gas stream by passing flue gas through a layer containing a sulfur dioxide acceptor such as copper alumina spheres. However, a preferred use of this invention is in hydrocarbon conversion processes, and in particular in moving bed catalytic reforming.

The present invention comprises a method and apparatus for maintaining a substantially continuous gas flow upward through the lower zone and then through the upper zone over a range of previously observed flow rates while moving particles downward from the upper zone to the lower zone.

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The lower zone has a higher internal pressure than the upper zone and the internal pressures can be changed independently. The particles are passed through the upper and lower zones during the implementation of the process by which the particles or gas are treated. Either or both zones may be used primarily for the gas and particle contact operation, or the other zone may be used primarily for storage and supply purposes.

It is an object of the present invention to avoid the use of mobile mechanical equipment in contact with particles.

It is also an object of the present invention to avoid the use of expensive and complex control instrumentation to maintain gas flow.

Another object is to provide a method and apparatus for performing particle transfer without substantially affecting the pressures within the upper and lower zones.

In a general embodiment, the present invention is a method in which (a) a gas is introduced into a lower zone, after which the gas passes from a lower zone to a hopper zone through a lower particle transfer tube communicating through the lower zone and the shutter zone an upper particle transfer conduit communicates sulkusuppilovyöhykkeeseen and the upper zone and wherein the upper zone of the lower part, the upper particle transfer conduit, sulkusuppilovyöhykkeen lower portion and the lower particle transfer pipe are fulfilled without interruption in the particles and wherein the particles in the flow downstream through the upper particle transfer conduit sulkusuppiloon is turned off when the level of sulkusuppilovyöhykkeessä particles have an upper particle in the region of the lower end of the transfer tube; • (b) simultaneously with step (a), gas is introduced from the barrier funnel zone to the upper zone by means of an upper gas pipe communicating with these zones and substantially equalizing the pressure therebetween; 5 82890 (c) raising the pressure inside the hopper zone to a value substantially equal to the pressure in the lower zone when the hopper zone is to be emptied, stopping the flow of gas through the upper gas pipe through them and directing gas from the lower zone to the lower zone. particles flowing downward through the lower particle transfer tube to the lower zone and causing the gas to flow from the hopper zone to the upper zone by the upper particle transfer tube, at a gas velocity that prevents the flow of particles downward through the upper particle transfer tube; and (d) stopping the gas flow through the lower gas pipe when the level of particles in the closure funnel zone drops to a predetermined low level point and at the same time causing a gas flow from the upper gas pipe to dissipate and a hopper zone, the particle flow continuing until the level of particles in the hopper zone rises to the region of the lower end of the upper particle transfer tube.

In another embodiment of the method of the present invention: (a) gas is continuously introduced into the lower zone; (b) passing gas upward from the lower zone to the barrier zone through a lower particle transfer tube communicating with the lower zone and the barrier zone at a velocity that prevents the flow of particles downwardly through the lower particle transfer tube; and substantially equalizes the pressure therebetween, which allows the particles to flow from the upper zone down to the closure funnel zone through the upper particle transfer tube communicating with the upper zone and the closure funnel zone; gas flow through the upper gas pipe, causing the gas to flow from the shut-off pilot zone the upper zone, the upper particle transfer tube to a gas rate which prevents downward flow of particles through the upper particle transfer conduit; (d) introducing gas from the lower zone into the hopper zone by a lower gas pipe communicating with these zones and substantially equalizing the pressure therebetween, causing the particles to flow downward through the lower particle transfer pipe to the lower zone; (e) stopping the gas flow through the lower gas pipe when the particle level in the hopper zone drops to a predetermined low level point and at the same time providing a gas flow through the upper gas pipe, re-establishing the gas flow causes the particles to flow from the upper particle transfer tube into the hopper zone.

Apparatus for carrying out a general embodiment of the present invention comprises: (a) an upper particulate zone maintained at a first variable pressure; (b) a lower particulate zone maintained at a second variable pressure that is independently higher than said first pressure; (c) a closure funnel zone located below the upper zone and above the lower zone; (d) means for continuously supplying gas to the lower zone; (e) an upper particle transfer tube in communication with the upper zone and the hopper zone; (f) a lower particle transfer tube communicating with the barrier funnel zone and the lower zone; ·; (g) an upper gas pipe and a shut-off valve in said pipe in communication with the upper zone and ** the shut-off hopper zone; 1 82890 (h) a lower gas pipe and a shut-off valve in said pipe communicating with the shut-off hopper zone and the lower zone; (i) means for generating a signal initiating the transfer of particles out of the upper zone and transmitting said start signal; (j) means for identifying the level of particles in the barrier zone and transmitting the signal when said level is at a predetermined low point; and (k) means for adjusting the position of said shut-off valves so that one of the valves is axial when the other is closed such that the gas flow path to the lower zone comprises either a lower particle transfer tube and an upper gas tube or an upper line transfer tube and a lower end and said start signal such that (i) upon receiving said start signal, the lower gas line shutoff valve opens to allow particulate flow from the downcomer zone through the lower particle transfer tube to the upstream of the downcomer, and the upper gas line shutoff valve is provided; and (ii) upon receipt of said level signal, the shut-off valve of the lower gas pipe closes, causing the gas to flow upward. through the particulate transfer tube at a rate that prevents particles from flowing downward through the lower particulate transfer tube, and the shut-off valve in the upper gas tube opens, allowing particles to flow from the upper zone through the upper particulate transfer tube to the hopper zone.

Figure 1 is a schematic representation of an embodiment of the present invention showing an upper zone, a hopper zone and a lower zone, each zone contained in a separate vessel; Figure 2 is a schematic representation illustrating the zones of Figure 1 in a common vessel and illustrating three steps in a five-stage cycle; implementation of the β 82890 form. Figures 2A, 2B and 2C illustrate steps 1, 3 and 5 of the cycle, respectively.

In order to facilitate the understanding of the principles of the invention, reference is now made to the embodiments shown in the drawings, and a specific exemplary process for a specific language is used to describe it. The use of these embodiments and this example is not intended to limit the scope of the invention in any way. The drawings show only those components which are necessary to illustrate the invention, the use of the required additional means being well within the scope of the art.

Reformation of hydrocarbon feedstocks, such as petroleum-derived naphtha, using a catalyst formed by a platinum group metal and alumina, is a well-known process in the art. Briefly, hydrogen is mixed with the naphtha feedstock and contacted with the catalyst in the reaction zone under temperature and pressure reforming conditions to effect at least partial refining of the naphtha feedstock to products having improved octane number. After a certain period of use, the catalyst used in the process must be regenerated, i.e. it must be treated to return it to a satisfactory level of activity and stability in order to catalyze the reforming reactions. Regeneration consists of several different process steps. In one step, the catalyst is contacted with a reducing gas consisting of hydrogen to carry out a reduction reaction. The aforementioned U.S. Patents 3,647,680 and 3,692,496 can be consulted for background information regarding reforming and catalyst regeneration.

‘In many modern catalytic reforming processes. . the catalyst is moved continuously or semi-continuously through a regeneration vessel or through a series of regeneration vessels in which the various steps of the regeneration cycle are performed. Due to the well-known difficulties associated with moving solids from one location to another mentioned above, true continuous processing is difficult to achieve. The catalytic regeneration process of the aforementioned U.S. Patents 3,627,680 and 3,692,496 discloses the use of semi-continuous transfer of catalysts at certain points and continuous transfer at other points in the regeneration vessel or vessels. Semi-continuous motion refers to the repetitive transfer of a relatively small amount of catalyst at adjacent times. For example, one catalyst charge can be transferred out of the vessel every other minute. If the warehouse in question. the vessel is large enough, the motion is approximately reminiscent of a continuous transfer of catalyst. This principle is used in this invention. It is not necessary to provide additional information on regeneration processes, as it is readily available from various sources, such as the aforementioned U.S. Patents 3,647,680 and 3,692,496, and is not required to understand this invention.

The following is a description of the embodiment of the invention shown in Figure 1 using a language specific to the reforming process described above. The catalyst particles accumulate in the vessel 10, or upper zone 10 of the bottom part arises from the top in the direction of arrow as shown. In this zone, that part of the catalyst regeneration cycle known as reduction takes place. The high temperature gas consisting of hydrogen is contacted with the catalyst particles in the upper zone 10 to perform the reduction.

It is very important to maintain an uninterrupted flow of gas through the reduction zone. If the flow were to be interrupted for some time, the reduction of the catalyst would not take place properly with the consequence that its ability to catalyze the reforming reactions would be severely impaired. Likewise, if the reduction gas flow is large enough to fluidize or partially fluidize the catalyst, the catalyst is subject to physical damage.

After the catalyst is reduced in the upper zone 10, it is transferred to the lower zone 12, which acts as a catalyst retention space flowing through the regeneration equipment and also performs an isolation function as the catalyst is fed to the pneumatic conveying means to transfer the catalyst to the reforming reactor. The lower zone 12 is at a higher pressure than the upper zone 10. The upper zone could be maintained at, for example, a nominal pressure of 34.5 kPa and allowed to vary between 13.8 and 55.2 kPa, while the nominal pressure of the lower zone could be 241.3 kPa with a normal range of 206. 9 - 275.8 kPa. Thus, the pressure difference between the upper and lower zones could range from 151.7 to 262 kPa. However, the present invention could be used when the pressure difference between the zones is much larger or much smaller. It can be between 0.7 and 689.5 or 1379 kPa or higher.

The container-shaped closure funnel 11 is used to transfer the catalyst from zone 10 to zone 12. The catalyst passes from zone 10 to the closure funnel 11 through the upper particle transfer tube 11. through a transfer tube 16 sealingly extending into sub-zone 12. As discussed below, extension of tube 16 to sub-zone 12 is not required; although a certain minimum pipe length is required, it may be outside the vessels ::. Extension of the tube 15 into the hopper 11 is not necessary when using a means for monitoring the particle level at a high position in the hopper 11, but is required when no upper level instrumentation is used. Such top-level instrumentation is not shown in Figure 1, as it is not necessary for the embodiment described therein, but is described below.

The general prior art procedure is to place the valves between the three vessels of the tubes 15 and 16 so that the closure funnel 11 can be alternately filled with catalyst from the upper zone 10 keeping the valve in the tube 16 closed, and then discharged into the lower zone 12 with the valve in the tube 15 closed. However, as mentioned above, it is highly desirable to avoid the use of mobile equipment, including valves, in catalyst particle transfer paths.

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The reduction gas enters the lower zone 12 through the pipe 20.

Valve 21 regulates the amount of gas flowing into the lower zone 12; this flow rate can be varied independently of the invention by means of adjusting the pressure in the lower zone 12 (not shown). For example, the pressure in the lower zone 12 could be varied in a previously established range according to the signals received from the above-mentioned pneumatic conveying means.

Gas may flow from the lower zone 12 to the upper zone 10 on either of the two alternative routes, where the hopper zone is part of both routes. The second gas flow path comprises a pipe 16, a shut-off funnel 11 and an upper gas pipe 13. The second flow path comprises a lower gas pipe 14, a shut-off funnel 11 and a pipe 15. Since the catalyst fills the bottom of the vessel 10 and the gas enters above the catalyst level, it is necessary to use means for conducting the gas downward and distributing it so that contact between the gas and the catalyst occurs. This is accomplished by a cylindrical septum 30 that is smaller in diameter than the upper vessel 10 and positioned centrally therein to form an annular space. The upper part of the annular space is closed from the gas flow by means of an annular horizontal plate. The open center of the annular plate allows the flow of catalyst and gas. The gas coming from the tube 13 into the annular space must therefore flow downwards to the bottom of the cylindrical partition wall 30 and turn 180 ° to flow upwards through the catalyst.

The internal pressure in the upper zone 10 is independently controlled by a device not shown in the drawing. For example, the upper zone 10 could be connected by a pipe to another vessel used in the catalytic reforming, so that the pressure in the upper zone depends on the vessel pressure and varies with it.

A low level switch 17 is located in the hopper 11 to detect when the catalyst level in the hopper zone is at a predetermined low level and to transmit a signal to the controller i2 82890 22. The controller 22 controls the positions of the valves 18 and 19, which are double acting valves in this embodiment of the invention.

The controller 22 also includes a timer that generates or causes to generate a cycle start signal at a frequency determined by adjusting the timer. The cycle start signal causes valves 18 and 19 to move to the beginning of the particle transfer cycle as described below.

The following description is presented with reference to both Figures 1 and 2.

The above description of Figure 1 also applies to Figure 2. It can be seen that the same reference numerals used in Figure 1 also appear in Figure 2, where applicable. Certain points have been omitted from Figure 2 to simplify the drawing, such as control 22 and valve 21, but must be understood that these points are necessary for the operation of the embodiment of Figure 2. In Figure 2, which shows the preferred arrangement, the three zones of Figure 1 are arranged in one container instead of separate containers. In Figure 1, the lower gas pipe 14 communicates with the lower zone 12 and the shut-off funnel 11 and the upper gas pipe 13 communicates with the shut-off funnel 11 and the upper: zone 10. In Figure 2, the gas pipes are shown having a common part 26. Thus, in Figure 2, the lower pipe 14 includes a part reference numeral 26 and the upper tube 13 includes a part indicated by reference numeral 26.

The transfer of catalyst particles from the reduction zone 10 to the lower zone without the use of valves while maintaining the gas flow through the zones can be accomplished in a five-phase cycle. Three of these five steps are shown in Figure 2. One cycle of cycle results in the transfer of a single particle charge from the upper zone to the lower zone. Figure 2A shows step 1 of the cycle, in which the apparatus is in the hold or standby position. The closure funnel 11 is filled with catalyst to its maximum capacity. Reduction zone 10 has a catalyst. a stock that remains in the zone long enough to achieve the appropriate reduction. Tubes 15 and 16 are filled with catalyst so that there is no discontinuity in the catalyst mass in the lower part of the reduction zone 10, 82890, in the upper transfer tube 15, in the lower part of the hopper zone 11 and in the lower transfer tube 16. The stock in the upper zone 10 is replenished with catalyst from the part of the regeneration plant located above the upper zone (not shown). Catalyst accumulation in sub-zone 12 is shown.

The gas passes from the lower zone 12 to the shut-off funnel 11 through the lower transfer pipe 16 during step 1. The pressure difference between the lower and closing hopper zones can be 0.7-689.5 kPa or more, with the lower value usually exceeding 34.5 kPa. The flow of particles downward from the hopper zone 11 to the lower zone 12 is currently represented by the upward flow of gas through the lower transfer tube 16. At a high gas flow rate upwards and at a relatively shallow depth of catalyst above the upper transfer tube, the particles in the tube 15 can be pushed upwards into zone 11, causing a large increase in gas flow and partial fluidization of the catalyst in zone 11. The design of the equipment must specify the minimum length of the pipe 16 and the minimum depth of the particle layer immediately above it based on the expected or required maximum gas flow through the pipe 16. When establishing this length as well as the depth above the minimum value, it is necessary to consider the required minimum gas flow and the pressure difference between the zones. The longer the pipe at a given pressure difference, the lower the gas flow. The diameter of the pipe can be increased to increase the gas flow by a given pipe length and pressure difference.

The flow of catalyst from the upper zone 10 to the hopper zone 11 does not currently occur (step 1) due to the level of particles in the hopper zone 11 being in the region of the end of the upper transfer tube 15; reference numeral 27 indicates the head area. It can be seen that in order for the catalyst to flow out of the tube 15 (Figure 2A) in the region of the end of the tube and outside the tube, the catalyst must be displaced. Sufficient force to carry out the displacement is not available in this situation and the level never rises above the head area.

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In stage 2 of the cycle (not shown), which may be called the pressurization stage, the valve 18 is closed and the valve 19 in the lower gas pipe 14 is open. This leads to equalization of the pressure between the hopper zone and the lower zone; thus, the pressure inside the hopper zone increases at this stage so that it becomes higher than the pressure inside the upper zone. At the end of the pressurization of the hopper zone, the cycle proceeds to step 3.

Figure 2B shows the latter part of step 3 of the cycle, in which the level of catalyst in the hopper zone 11 is close to its normal lower point. Step 3 is referred to as the "empty" portion of the cycle in which the closure funnel is emptied of catalyst. The flow of solids from the upper zone to the hopper zone is blocked by the upward flow of gas through the upper transfer tube 15 in the same manner as described above for the tube 16. The level of particles in the shut-off funnel zone decreases as solids flow out of the pipe 16 into the lower zone 12. During this time, the gas entering through the pipe 20 flows through the lower gas pipe 14 and the valve 19 into the shut-off funnel zone. The pressures in the lower zone and the hopper zone are substantially the same at this time (step 3), although naturally a small pressure difference exists due to the flow through the pipe 14.

It can be seen that the gas flow path in steps 2 and 3 is different from in step 1, but that no gas flow interruption occurs in the transition from step 1 to step 2. Arrows 28 indicate the gas flow path in step 1 and arrows 29 indicate gas flow in step 3. It may be desirable to program a slight delay 18 closure phase! 2 at the beginning, which is a class of a few seconds or less. This would ensure that if the valve 19 were to open relatively slowly, no significant transient flow disturbance would occur; due to the operation of the valve.

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When the level in the hopper zone 11 drops to a predetermined lower point, step 4, the pressure release is initiated. The lower stage switch 17 detects the absence of particles at said lower point as soon as the particle level drops to this point and immediately sends a signal to the regulator 22. The regulator 22 causes the valve 19 to close and the valve 18 open, thus releasing pressure from the hopper zone 11 and changing gas flow paths in step 1. Step 4 ends when the pressure in the hopper zone becomes substantially equal to the pressure in the upper zone. In step 5, the catalyst enters the hopper zone through line 15. Step 5 differs from step 1 in that the hopper 11 is full during step 1 and no catalyst flow occurs in step 1. During step 5, catalyst flows from the upper zone 10 to the hopper zone 11 until the level rises to the upper transfer tube 15 end, which terminates the cycle and returns represents step 1.

This five-phase cycle is normally repeated continuously. For example, it may take about 50 seconds to transfer one catalyst charge from the upper zone 10 to the lower zone 12. The controller 22 is capable of accepting the desired cycle repetition rate, which is usually set manually, and transmitting a signal to initiate the cycle, i.e. valves 18 and 19. 2. In practice, the maximum playback speed of a cycle for a cycle of 50 seconds would be about once every 60 seconds. The catalyst transfer rate would then be if the volume of the hopper zone between the normal maximum capacity (level in the region of the 15 ends of the tube) and the lower level switch was one volume unit, one volume unit per minute. A transfer rate of half this maximum would require the controller 22 to initiate a new cycle every two minutes.

The controller 22 serves as a means for receiving a level signal from the low level switch 17, as a means for adjusting the positions of the shut-off valves 18 and 19, and as a means for the user to set the repetition rate of the 16 82890 cycle. There are many different types of devices capable of performing the functions of the controller 22, such as process control computers and programmable controllers. These tasks can also be performed by a cycle timer to generate signals to initiate the cycle, and by a flip-flop control device that responds to the low level switch 17 to generate signals to initiate phase 4.

The lengths of the tubes 15 and 16 are quite important for the operation of the system, as described above. The magnitude of the allowable pressure difference between the zones depends mainly on the length of the particle column with the given transfer tube diameter and particle type between the zones. The length of the particle column between the zones is defined as the length of the layer depth of the transfer tube plus the particles in the zone above it, such that the lowest point of the particle layer is at the bottom of the conical portion of the zone.

If the pressure difference is too large, the catalyst will be blown out of the transfer tube and into the zone above it.

When the pressure in the zone was increased in the experimental study, the blow-out was indicated by a loud noise and could be clearly detected in the zone above the transfer tube. If the pressure difference between the zones is too small, the gas flow rate is too small, leading to poor catalyst regeneration. The catalyst-y droplet through which the gas flows upwards can be viewed as flow resistance; the flow rate through such a resistor or restrictor varies with the pressure drop across the restrictor.

In a typical design situation, the pressure difference across the hopper is known, as it is normally determined independently by factors that are not dependent on the hopper system.

Thus, the starting point for the design is the given pressures of the upper and lower zone pressure ranges. The required maximum and minimum gas flow rates are also known as determined by the process. The length of the catalyst column and the diameter of the particle transfer tube are then considered. A balance between length and diameter is required to achieve the desired gas i7 82890 velocity at the same time as the desired instantaneous particle flow rate. Decreasing the length while other factors remain constant or increasing the diameter while other factors remain constant will result in blow-out if taken too far. Another important feature in the design is the length of all the components that make up the total column height of the particles. The gas flow through the transfer tube requires a significantly greater pressure drop per unit length than the same gas flow through the particle layer immediately above the transfer tube. It should also be noted that the gas flow rate through the particle layer must always be less than the rate that causes the particles to float. Those skilled in the art can now evaluate the interaction of the variables and how to adjust each to obtain the appropriate structure. The principles of solids flow are familiar to those skilled in the art and need not be described here. For further information regarding solids flow in connection with this invention, the aforementioned U.S. Patent 2,851,401 may be consulted, although it does not relate to gas flow.

It should be noted that it is common practice in the design of solid flow systems to perform experiments to determine the flow properties of the particular solid in question.

It can be seen that the design of the system of the present invention requires careful calculations. Once the internal pressures in the upper and lower zones, the minimum and maximum gas flow rates required by the process, the gas and particle types, and the required range of particle transfer rates are given, the system designer must carefully select the size of the hopper zone, especially the normal minimum and maximum volume depth above the transfer tube, diameter of the transfer tubes, and lengths of the transfer tubes. Naturally, the designer must choose other parameters, such as the size of the gas tube, but these are the most important.

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It will be readily apparent with reference to Figure 2 and the flow paths indicated by the successive arrows 28, 29 and 32 in Figures 2A, 2B and 2C that the two alternating flow paths between the outlet of the pipe 20 and the top of the upper zone 10 contain substantially the same pressure drop at each time. The pressure drop of the gas flowing through the catalyst in large parts of the apparatus is small compared to the pressure drop of the gas flowing in the transfer pipes.

The apparatus of the present invention can be used as a solids flow control device for the entire process, as the particle flow rate from the upper zone to the lower zone can be varied, as described above.

It is necessary that the lower end of the particle transfer tube have a smaller cross-sectional area; this is called contraction. For example, in the case of a round tube, the inside diameter of the head may be smaller than the rest of the tube, as shown in Figure 2A by reference numeral 27. The purpose of the contraction is to keep the particle transfer tube full of particles when the pressures in the zones to which the transfer tube is connected are approximately the same. When the pressures are not equal and the gas flows upwards, the particles remain in the tube due to the appropriate choice of the length and size of the tubes 15 and 16 to set the length of the particle column between the zones and thus to prevent blowing out as described above. Without shrinkage, the particles passing through the tube are in a dilute phase, and when a pressure difference between the zones is achieved, the tube is partially filled with particles, which invalidates the invention.

In another embodiment of the present invention, the upper level sensor may be used to limit the level of particles in the hopper zone to a point below the end region of the upper particle transfer tube. When the top-level point is adjustable within a certain range, the size of each transferred bet can be adjusted. When the shut-off hopper zone reaches the upper level point, the upper level sensor provides a signal to the controller 22 and the controller i9 82890 22 closes the upper gas pipe shut-off valve, also leaving the lower pipe shut-off valve in the closed position. The gas path between the upper and lower zones then comprises both an upper and a lower particle transfer tube, so that the flow of particles in each tube is blocked. In this case, when it is desired to start the cycle from this holding position, which comprises two closed shut-off valves, the shut-off valve of the lower gas pipe is opened to start the emptying phase of the shut-off funnel.

The reason for using an upper level instrument instead of allowing the particle level to rise in the lower end region of the upper particle transfer tube is that in this situation the gas flowing up the tube tends to mix the particles in the lower end region. This mixture can cause physical damage to the particles. Another method that has been proposed to solve this problem, if any, is to use a torn section of pipe at the lower end of the pipe. All or part of the gas would then flow through the perforations, thus bypassing the catalyst and without causing agitation. The level of the catalyst would not rise above the lower end of the perforated part of the tube.

Claims (6)

A method for maintaining a substantially continuous upstream gas flow through a high pressure lower zone and then through a low pressure upper zone, in which particles are continuously added while the particles are transferred down-saturated from the upper zone to the lower zone. barrier funnel zone which is continuously poured open and joined to the upper zone by means of an upper particle guide tube and to the lower zone by means of a lower particle guide tube, characterized in that in the process (a) a gas is conducted to the lower zone, after which the gas is upstream from the lower zone to the barrier funnel zone through the lower particle guide tube at a rate that prevents the flow of particles downstream through the lower particle transfer tube while the gas is led from the barrier funnel zone to the upper zone by means of the upper gas tube substantially equalizes the pressure therebetween and the particles a is allowed to fill the lower portion of the upper zone, the upper particle casing, its lower portion of the barrier funnel zone, and the lower particle casing until the flow of particles through the upper particle casing to the barrier funnel is prevented within the lower area of the barrel, where the particles the upper particle guide tube; (b) raising the internal pressure of the barrier funnel zone to a value substantially equal to the pressure of the lower zone, by stopping the gas flow through the upper gas tube and by passing the gas from the lower zone to the barrier funnel zone by means of the lower gas tube; which joins these zones and substantially equalizes the pressure therebetween and causes the particles to flow downwardly through the lower particle guide tube to the lower zone and allows the gas to flow from the barrier funnel zone to the upper zone by means of the upper particle guide tube, which flushes the gas through the upper particle guide tube; and (c) the gas flow through the lower gas pipe is stopped as the level of the particles in the blocking funnel zone drops to a predetermined low point, and at the same time the gas flow, determined at step (a), begins, which causes the particle flow from the lower particle feed tube to the stop and allow the particles to flow from the Upper Particle Liner to the Funnel Zone. 2. A method according to claim 1, characterized in that the cycle comprising steps (a) - (c) is repeated continuously at a sufficient speed to achieve the desired transfer rate of the particles from the upper zone to the lower zone. A method according to claim 1 for maintaining a substantially continuous gas flow through a lower particle-containing zone and then through an Upper particle-containing zone having a predetermined flow rate range at the same time as the particles are transferred downstream from the lower zone to the upper zone. the lower zone exhibits a higher internal pressure than the upper zone and the particles are passed through the upper and lower zone during the process of treating particles and gases, characterized in that in said method: (a) a gas is continuously fed to the lower zone ; (b) the gas is fed upstream from the lower zone into a barrier funnel zone through a lower particle guide tube connected to the lower zone and to the barrier funnel zone at a rate that prevents the flow of particles downstream through the lower particle guide tube and simultaneously the gas is fed from the lower funnel zone the zone by means of the Upper gas tube which joins these zones and substantially equalizes the pressure therebetween and allows the particles to flow from the Upper Zone down to the barrier funnel zone through the Upper Particle Liner which joins the upper zone and barrier; (c) as the level of the particles contained in the barrier funnel zone rises to a predetermined high point, the internal pressure in the barrier funnel zone is increased by stopping the gas flow through the upper gas tube, causing the gas to flow from the barrier funnel zone to the upper zone. 82890 the particle casing at a gas velocity which prevents the flow of particles downstream through the upper particle casing; (d) thereafter, the gas is conducted from the lower zone to the barrier funnel zone by means of the lower gas tube which is associated with these zones and substantially equalizes the pressure therebetween, causing the particles to flow downwardly through the lower particle guide tube to the lower zone; and (e) the gas flow through the lower gas pipe is stopped as the level of the particles in the blocking funnel zone drops to a predetermined low point, and at the same time a gas flow through the Upper gas pipe is caused, which in turn stabilizes the gas flow form of the step (b) and decreases the flow of the particles. the particle guide tube moves to the lower zone to stop and causes the particles to flow from the upper particle guide tube into the blocking funnel zone. Method according to claim 3, characterized in that the cycle comprising the steps (b) - (e) is repeated continuously at a sufficient rate to achieve the desired particle transfer rate from the upper zone to the lower zone. 5. Device for maintaining a substantially continuous gas flow up through a lower zone and then through an Upper zone with a predetermined flow rate range while transferring particles downward from the upper zone to the lower zone without allowing the particles to come into contact with the movable zone. the device and without substantially operating on the internal pressures of the upper and lower zones such that the particles are passed through the upper and lower zones simultaneously with the process of processing particles or gases, characterized in that said device comprises: (a) an upper particle containing zone (10) which is poured into a first pressure which can be independently changed; (b) a lower particle-containing zone (12) which is poured into a second pressure which can be independently altered and which is higher than said first pressure; (c) a barrier funnel zone (11) located below the upper zone and above the lower zone; (d) means (20) for continuously feeding the gas into the lower zone; (e) an Upper particle guide tube (15), the lower end of which has a restriction and which is joined to the Upper zone and the blocking funnel zone; (f) a lower particle guide tube (16), the lower end of which exhibits a restriction and which is joined to the blocking funnel zone and the lower zone; (g) an Upper gas pipe (13) and an Upper closing valve (18) present in said pipe, which pipe is connected to the Upper zone and the blocking funnel zone; (h) a lower gas pipe (14) and a lower closing valve (19) present in said pipe, which is connected to the blocking funnel zone and to the lower zone; (i) a control device (22) for initiating the filling funnel filling by opening said upper closing valve and by closing said lower closing valve, for sensing when the level of the particles within the blocking funnel when the desired high value, initiating the discharge of the particles from the freezing zone to the lower zone by closing the upper closing valve and by opening the lower closing valve, to detect when the level of the particles within the blocking funnel zone drops to the predetermined position value and initiating the filling of the blocking funnel zone again. Device according to claim 5, characterized in that said control device comprises: (a) means for generating a signal which initiates the transmission of the particles from the upper zone (10) and for transmitting said triggering signal, (b) means ( 17) to sense the level of the particles within the blocking funnel zone (11) and to transmit the signal where said level is at a predetermined low point; and (c) means for controlling the positions of said closing valves (18, 19) such that one valve is open where the other valve is closed so that the flow path of the gas fed adjacent the lower zone comprises either: the lower particle guide tube (16) and the upper gas tube (13) or upper particle guide tube (15) and the lower gas tube (14), each position control means responds to said level signal and to said triggering signal so that (1) upon receiving the said shut-off valve opens the shut-off valve in the lower gas pipe and allows the particles to flow from the barrier funnel zone through the lower particle transfer tube to the lower zone, and the shut-off valve in the upper gas pipe closes and allows the gas to flow upwardly through the upper pipe through the upper pipe. the flow of particles downstream through the Upper Particle Guide tube, and (ii) upon receipt of said level the valve closes the shut-off valve in the lower gas pipe, which allows the gas to flow up through the lower particle casing at a rate that prevents the flow of particles down through the lower particle casing, and the shut-off valve in the upper gas pipe opens the outer casing and allows the particles to flow. the particle guide tube to the blocking funnel zone.