CS268679B2 - Apparatus for maintaining a continuous flow of gas flow - Google Patents

Abstract

The device consists of an upper zone, a lower zone and a zone forming a closing hopper, which is located between the upper and lower zones. Between the upper zone and the zone forming the closing hopper is located a transport pipe for transporting particles with a constriction in its lower parts connecting the lower part of the upper zone with the upper part of the zone forming the closing hopper. Between this zone and the lower zone is a lower transport pipe for transporting particles with a constriction in its lower part connecting the lower part of the zone forming the closing hopper with the upper part of the lower zone. The upper zone and the zone forming the closing hopper are connected by an upper gas pipe, and this zone and the lower zone are connected by a lower gas pipe. The device includes a level signal element, the sensor of which is located in the zone forming the closing hopper for detecting the filling level in this zone, and a control element for receiving a signal determining the filling level from the level signal element and for inducing a signal to open and close the upper closing valve and the lower closing valve.

Description

The invention relates to a device for maintaining a continuous flow of a gas stream in an upward direction through the lower zone and then through the upper zone while simultaneously transporting particles downward from the upper zone to the lower zone, without contact of these particles with the transport means and without significantly affecting the internal pressure in the upper and lower zones. The device according to the invention is particularly useful for the regeneration of catalysts.

As far as the prior art is concerned, the closest solution to similar types of devices can be found in United States Patent No. 2,851,401 (author Payne). This patent describes a device in which solid particulate material is transported from one location to another, but unlike the present invention, this cited patent does not contain any information regarding maintaining a gas flow through said locations or maintaining a pressure in those locations between which said material is transported, nor does this cited patent contain any information regarding the use of gas pipes, which are used in the present invention. In another United States Patent No. 3,851,402 (author Haddad) a further description regarding the transport of solid material can be found, and this patent is based on the aforementioned Payne Patent No. 2,851,401.

One possible application of the apparatus of the present invention is in the field of hydrocarbon conversion. Examples of methods for transporting and handling catalysts used in hydrocarbon conversion include those disclosed in U.S. Patents Nos. 2,423,411 to Simpson, 2,531,356 to Simpson et al., 2,854,156 to Payne, 2,854,161 to Payne, and 2,985,324 to Balentine.

Further information regarding catalytic reforming and catalyst regeneration processes, which may be considered a more general example of the above process, can be found in U.S. Patent No. 3,647,680 to Greenwood et al. and U.S. Patent No. 3,692,496 to Greenwood et al.

There are many chemical processes in which it is necessary to bring a gas and a solid particulate substance or substances or various particles into contact. During this contact, chemical reactions and also physical phenomena very often occur. In most cases, it is necessary to bring the gas and the solids into contact for a minimum time interval, and if this contact is carried out for a shorter time interval, then the desired chemical or physical reaction or change does not occur or this reaction or chemical change does not take place completely.

In some cases, there is a maximum time interval for which the contact is carried out, beyond which less than optimal results or even undesirable results are obtained. In carrying out these processes, it is very advantageous to carry out the contacting of the gas and solid in a continuous manner or in a semi-continuous manner, which is preferable to the batch method.

The zone in which the gas and solid are contacted is usually maintained at a certain pressure (this pressure is higher than atmospheric), which is created by the pressure of the gas supplied for contacting. The solid particles must be supplied to this pressure zone and removed from this zone in such a way as to avoid losses of the gas supplied for contacting to the surrounding atmosphere. Furthermore, in carrying out these processes, it is often necessary to maintain the internal pressure in the contact zone at a certain value or within a certain range. The pressure in the contact zone may be higher than the pressure maintained at the point from which the solids are supplied to the contact zone. Feeding solids into a zone that has a higher pressure causes numerous problems. In the case where such devices as a screw conveyor or a star hopper or various valves are used, then there is contact between the device and the solid particles, whereby the solid material is degraded, in which the solid material particles are crushed into even smaller particles, and the device is also worn out. In carrying out these procedures, it is also very difficult to achieve effective sealing of the contact zone in order to prevent gas leakage from this contact zone,

OS 268 679 B2 . c whereby the costs of the equipment are also very high. These problems are further compounded in cases where the solids and the gas are both in a state of elevated temperature. Up to now, in the implementation of these processes, pressure closing systems based on a two-position valve have been used in a preferred embodiment, through which the solid is guided, and this solid is then introduced into the pressure zone; however, these two-position valves are a very expensive element of these systems. Systems that use these valves and other other valves will be described in the following.

United States Patent δ. 2,851,401, cited above, addresses the problem of transporting solids, and addresses the transport of solids without the use of mechanical equipment that could wear out or degrade the solids. However, on the other hand, this patent does not address the various aspects related to gas conduction mentioned above. It should also be noted that it is often desired to maintain a continuous gas flow even though the solids flow is batch. By using a continuous gas flow, better control and regulation of the time interval between the contact of the two substances can be achieved, and usually this continuous gas flow promotes chemical or physical processes that occur due to the constant presence of fresh gas and solids. In some cases, it is very important to immediately contact the supplied solid with fresh gas, that is, with gas that has not yet been substantially contacted with the solid.

In the process of reforming a hydrocarbon feedstock, such as a naphtha fraction obtained from crude oil, platinum group metal catalysts supported on alumina are used, and these processes are well known in the art. Briefly, the naphtha feedstock is mixed with hydrogen and then contacted with a catalyst in a reaction zone under reforming conditions including temperature and pressure suitable for converting at least a portion of the naphtha feedstock to products with a higher octane rating. After a certain period of time in this process, the used catalyst must be regenerated, that is, the catalyst must be restored to its original quality. By this restoration of the original quality of the catalyst is meant such a treatment of the catalyst that its activity and stability are restored to such an extent that the catalyst is suitable for catalyzing reforming reactions. This regeneration consists of several different processing steps.* One of these steps involves contacting the catalyst with a reducing gas containing hydrogen to effect a reduction reaction. Basic information on the implementation of the catalyst reforming and regeneration process can be found in the above-cited United States Patents Nos. 3,647,680 (Greenwood et al.) and 3,692,496 (Greenwood et al.).

In many modern catalytic reforming processes, the catalyst is passed through a regeneration vessel continuously or semi-continuously, and it is also possible to use a series of regeneration vessels in which the various stages forming a regeneration cycle are carried out. Due to the well-known difficulties associated with the transport of solids from place to place, which have been described above, it is very difficult to achieve a truly continuous process in practical conditions. In the catalyst regeneration process according to the above-mentioned United States patents, the author of which is Greenwood, semi-continuous movement of the catalyst is used at certain points, while a continuous process is used at other points in the regeneration vessel or vessels. By said semi-continuous movement of the catalyst is meant the repeated movement of relatively small amounts of catalyst in narrowly defined spaces in a certain time. For example, it can be stated that one batch of catalyst is removed from the vessel every two minutes. If the supply of material in the vessel is sufficiently large, then this movement approaches the continuous character of the catalyst transport. Further information regarding the performance of regeneration procedures need not be provided, as this information is readily available from numerous sources, such as the aforementioned United States patents,

CS 268 679 B2 3 by Greenwood, and the presentation of this additional information is not necessary in explaining the invention.

The object of the present invention is to develop a device for maintaining a continuous upward flow of a gas stream through a lower zone and then an upper zone while simultaneously transporting particles downward from the upper zone to the lower zone, which avoids the use of moving means or mechanical devices to maintain a continuous gas flow.

It is also an object of the present invention to avoid the use of expensive and complex means for maintaining a continuous gas flow in the device.

Another object of the invention is to develop a device in which particle transport would be achieved without significantly affecting the internal pressure in the upper and lower zones.

The essence of the device for maintaining a continuous flow of gas in the upward direction through the lower zone and then the upper zone while simultaneously transporting particles downward from the upper zone to the lower zone, without contact of these particles with the means of transport and without influencing the internal pressure in the upper and lower zones, consists, according to the invention, in that it consists of an upper zone containing particles, a lower zone also containing particles and a zone forming a closing hopper, located between the upper zone and the lower zone. A gas pipeline is introduced into the lower zone for continuous gas supply to the lower zone. Between the upper zone and the zone forming the closing hopper, an upper transport pipeline is located, provided in its lower part with a constriction and connecting the lower part of the upper zone with the upper part of the zone forming the closing hopper, where between the zone forming the closing hopper and the lower zone, a lower transport pipeline is located, on the lower part of which a constriction is formed, and connecting the lower part of the zone forming the closing hopper with the upper part of the lower zone. The upper zone and the zone forming the closing hopper are connected by an upper gas pipe in which the upper closing valve is included, and the zone forming the closing hopper and the lower zone are connected by a lower gas pipe in which the lower closing valve is located, and further, in the zone forming the closing hopper, a sensor of the level signal member is located, connected to the regulating member for receiving a signal from the level signal member and further connected to the upper closing valve and the lower closing valve.

The advantages of the device according to the invention lie in the possibility of controlling the gas flow between the individual zones containing solid particulate material and in the possibility of controlling the internal pressure in these zones through which the solid particulate material is transported. The device does not use any mechanical means that would cause the solid particulate material being processed to be pulverized and therefore these parts cannot be damaged. The device is particularly suitable for processing solid catalytic parts or for regenerating these catalytic materials.

In the apparatus of the present invention, it is possible to maintain a substantially continuous flow of gas in an upward direction through the lower zone and then through the upper zone within a predetermined flow rate range while simultaneously transporting a portion downward from said upper zone to said lower zone.

The lower zone is at a higher pressure than the upper zone, and both of these internal pressures in said zones can be varied as desired. In the practical implementation of the process in the apparatus according to the invention, in which solid particulate material or gas is processed, said particles are guided through the upper zone and the lower zone. Either both zones or one zone may serve mainly for contacting the gas and particles, or one zone may be used mainly for storing the material and for feeding this material into the processing process.

The device according to the invention in its general embodiment therefore consists of the following parts:

- an upper zone which is filled with particles, this zone being maintained at an independently variable pressure,

EN 268 679 B2

- a lower zone, which is also filled with particles, this zone also being maintained at an independently variable second pressure which is higher than said pressure in the upper zone,

- a zone forming a closing hopper, which is located below the upper zone and above the lower zone,

- means for continuously supplying gas to the lower zone,

- an upper transport pipe for transporting particles, which is located between the upper zone and the zone forming the closing hopper, < * a lower transport pipe for transporting particles, which is located between the zone comprising the closing hopper and the lower zone,

- an upper gas pipe and a shut-off valve located in this pipe, said pipe being located between the upper zone and the zone forming the shut-off hopper,

- a lower gas pipe and a shut-off valve located in this pipe, said pipe being located between the zone forming the shut-off hopper and the lower zone,

- means for generating a signal that initiates the transport of particles from the upper zone and means for transmitting this initiation signal,

- means for sensing the level of particles in the zone forming the closing hopper and for transmitting a signal when said level is at a predetermined lower level, and

- means for regulating the position of said shut-off valves.

The position of these valves is regulated in such a way that one valve is open while the other valves are closed, so that the gas passage that is supplied to the lower zone of the device includes either the lower transport pipe for transporting particles and the upper gas pipe or the upper transport pipe for transporting particles and the lower gas pipe, the means for regulating the position being adjustable according to said level signal and according to said initiation signal.

After the said initiation signal is transmitted, the lower gas line shut-off valve is opened, thereby allowing the particles from the zone forming the shut-off hopper to flow through the lower particle transport pipe to the lower zone, and the upper pipe shut-off valve is closed, thereby allowing the gas to flow upwardly through the upper particle transport pipe. This gas has a flow rate such that it prevents the particles from flowing downwardly through the upper particle transport pipe.

After the level signal is converted, the lower gas line shut-off valve is closed, allowing gas to flow upward through the lower particle transport line at a rate that prevents the flow of U-particles downward through the lower particle transport line, and the upper gas line shut-off valve is opened, allowing particles to flow from the upper zone through the upper particle transport line to the zone forming the closing hopper.

In general, the processing in the apparatus according to the invention can be described as follows. Gas is supplied to the lower zone, passing upwards from the lower zone to the closure hopper zone via a lower particle transport pipe which is located between the lower zone and the closure hopper zone. The flow rate of this gas stream prevents particles from falling downwards through this lower particle transport pipe. The lower part of the upper zone, the upper particle transport pipe, the lower part of the closure hopper zone and the lower particle transport pipe are filled with particles, this filling being uninterrupted, and in the case where the level of particles in the closure hopper zone is in the lower limit region of the upper particle transport pipe, then the flow of particles downwards through the upper particle transport pipe into the closure hopper is prevented.

CS 26Θ 679 B2 5 hoppers.

At the same time, gas is led from the zone forming the closing hopper to the upper zone via an upper gas line which connects both of these zones and which essentially equalizes the pressure differences between these zones.

In the event that the zone formed by the closing hopper is emptied, whereby the gas flow through the upper gas line is stopped and the gas is led from the lower zone to the zone forming the closing hopper via the lower gas line which connects both these zones and which essentially equalizes the pressure differences between these zones, then the internal pressure in the zone forming the closing hopper is increased to a value substantially corresponding to the pressure in the lower zone, thereby achieving a downward flow of particles through the lower particle transport line to the lower zone. Furthermore, the gas flow from the zone forming the closing hopper to the upper zone is adjusted via the upper particle transport line, the gas flow rate being so great as to prevent the particles from flowing downward through the upper particle transport line*

When the level of particles in the zone forming the closing hopper drops to a predetermined lower level, the gas flow through the lower gas pipe is stopped and the gas flow through the upper gas pipe is resumed, thereby causing the flow of particles from the lower transport pipe for transporting particles to the lower zone to cease and at the same time causing the particles to flow from the upper transport pipe for transporting particles to the zone forming the closing hopper, and this flow of particles continues until the level of particles in the zone forming the closing hopper reaches the lower boundary region of the upper transport pipe for transporting particles.

The accompanying drawings show an apparatus for carrying out a process for processing solid particulate material while maintaining a continuous upward flow of gas through the lower zone and then the upper zone, while simultaneously transporting the solid particles downward from the upper zone to the lower zone. Fig. 1 shows a schematic representation of a device according to the invention, which is formed by an upper zone, a zone forming a closing hopper and a lower zone, each of these zones being formed by a separate vessel. Fig. 2 shows a schematic representation of the individual zones according to Fig. 1, which are located in a single vessel, and this figure shows three stages of a five-stage cycle, which together form the entire processing process carried out in this device according to the invention. Individual Figs. 2A, 2B and 2C show the first, third and fifth stages of this cycle.

The device according to the invention and the processing method in this device will be explained in detail with the help of these drawings, while in this description the terminology "tabulating" will be used to one of the possible exemplary processing methods in which this device according to the invention is used. The presentation of this exemplary embodiment of the device according to the invention does not limit the scope of the invention in any way. The figures show only the elements and features that are necessary to illustrate this device according to the invention, while the use of other necessary means is generally known to those skilled in the art.

In the following, with the aid of Figure 1, an apparatus for carrying out the catalyst regeneration process which has been detailed in the prior art section will be illustrated, the terminology used specifically relating to the reforming process and from which the catalyst to be regenerated also originates. The catalyst particles are collected in the lower space of a vessel, which vessel forms an upper zone 10. These catalyst particles are fed into this zone from above, as shown by the arrow. In this zone, a part of the catalytic regeneration cycle takes place which is referred to as catalyst reduction. In this upper zone 10, a gas containing hydrogen and having a high pressure is brought into contact with the catalyst particles in order to carry out the reduction of these catalyst particles.

At this stage, it is very important to maintain an uninterrupted gas flow through this reducing valve.

CS 268 679 82 nou. If this gas flow is interrupted for any period of time, then the reduction of the catalyst is not achieved to a sufficient extent, which is reflected in the fact that the ability of this catalyst to catalyze the reforming reaction is significantly impaired. It should also be noted that in the case where the flow rate of the reducing gas is excessively high, then the catalyst is brought into a fluid state or into a partially fluid state, in which state this catalyst is subjected to physical damage.

After the reduction of the catalyst in the upper zone 10, the catalyst is transferred to the lower zone 12, which serves as a retention proctor for the catalyst passing through the regeneration device, and this upper zone also has an insulating function, since it protects the catalyst before it is fed as a coated material by means of pneumatic conveying means serving to transport the catalyst to the reforming catalyst. This lower zone 12 operates at a higher pressure than the upper zone 10. For example, it is possible to consider that the upper zone can be maintained at a nominal pressure of 34.5 kPa gauge, while the pressure value in this upper zone can vary in the range from 13.8 to 55.2 kPa gauge, while the nominal pressure in the lower zone can be 241.3 kPa gauge, while this pressure usually varies in the range from 206.9 to 275.8 kPa gauge. From the above, it follows that the pressure difference between the upper and lower zones can range from 151.7 kPa to 262 kPa. However, it is obvious that the process according to the above description can be carried out with a pressure difference between the two zones much larger or much smaller than the exemplary range. For example, it can be stated that this pressure difference can range from 0.7 to 689m5 kPa up to 1379 kPa or even higher values.

To transport the catalyst from the upper zone 10 to the lower zone 12, a zone 11 forming a closing hopper is used. The catalyst is discharged from the upper zone 10 to the zone 11 forming a closing hopper by means of an upper transport pipe 15 for transporting particles, this pipe being sealed in a flange in the upper part of the zone 11 forming a closing hopper and passing into this zone 11 forming a closing hopper. The catalyst is then further guided from the zone 11 forming a closing hopper to the lower zone 12 by means of a lower transport pipe 16 for transporting particles, which passes into the lower zone 12, this pipe being sealed at the point of passage into this zone. As will be explained further in the text, this passage of the lower transport pipe 16 into the lower zone 12 is not necessary, and in cases where a minimum length of this pipe is required, this pipe can then be arranged outside the said vessels. In the case where means for monitoring the level of particles are arranged at the upper level in the zone 11 forming the closing hopper, then the passage of the upper transport pipe 15 into the zone 11 forming the closing hopper is not necessary, however, in the case where these means for monitoring the level of particles in the upper space are not applied, then this passage of the transport pipe 15 into the zone 11 is necessary. In the attached Fig. 1, this equipment for monitoring the level in the upper space of the zone 11 forming the closing hopper is not shown, because it is not necessary from the point of view of the description of the embodiment shown in Fig. 1, however, the function of these means will be described further.

A commonly used feature according to the prior art in these embodiments is the placement of valves in the pipes 15 and 16, which are arranged between the three vessels, so that the zone 11 forming the closing hopper can alternatively be filled with catalyst from the upper zone 10 with the valve in the pipe 16 closed, while the catalyst can be further discharged to the lower zone 12 with the valve in the pipe 15 closed. However, as already mentioned above, it is highly suitable and in practice preferable to carry out the transport and guidance of catalytic particles without the use of a device with moving parts.

The reducing gas enters the lower zone 12 via a line 20. The amount of gas supplied to the lower zone 12 is controlled by a valve 21. This gas flow rate can be independently varied during this process by means of a pressure control means in the lower zone 12 (not shown). For example, the pressure in the lower zone 12 can be adjusted to move within a predetermined range, depending on a signal derived from the above-mentioned pneumatic conveying means.

EN 268 679 82 7

The gas can flow from the lower zone 12 to the upper zone 10 via one or two flow paths, with the zone 11 forming the closing hopper forming part of each of these paths. One of these gas flow paths is formed by the lower transport pipe 16 for transporting particles, the zone 11 forming the closing hopper and the upper gas pipe 13. The second flow path includes the lower gas pipe 14, the zone 11 forming the closing hopper and the upper transport pipe 15 for transporting particles. With regard to the above-mentioned first conduit or gas path, in which the catalyst fills the lower part of the upper zone 10 and the gas enters above the level of the catalyst in this vessel, it is necessary to provide means in this upper zone 10 for conducting the gas downwardly in this zone and for distributing this gas in such a way that contact between the gas and the catalyst in this zone occurs. This is achieved by means of a cylindrical baffle 30 having a smaller diameter than the diameter of the upper zone 10, said baffle being positioned coaxially within said vessel and forming an annular space. The upper end of said annular space is closed by means of an annular horizontal plate, so that no gas can pass therethrough. The open central region of the annular baffle allows the flow of catalyst and gas. The gas which enters said annular space via the pipe 13 must therefore flow downwards into the lower part of said cylindrical baffle 30 and then turns by 180° and flows in an upward direction through the catalyst.

The internal pressure in the upper zone 10 is independently controlled by means not shown in the figure. For example, the upper zone 10 may be connected by piping to another vessel used in the catalytic reforming process, such that the pressure in the upper zone is dependent on and varies with the pressure in that vessel.

The lower level switch 17 is located in the zone 11 forming the closing hopper in order to signal the moment when the catalyst level in the zone 11 forming the closing hopper is at a predetermined lower level, and to transmit this signal to the control member 22. By means of this control member 22, the position of the closing valves 18 and 19 is adjusted, whereby in this embodiment according to the invention two-position valves are used. The control member 22 also includes a timer which generates or causes to be generated a cyclic initiation signal with a frequency determined by the setting of the timer. This cyclic initiation signal controls the valves 18 and 19 in order to start the particle transport cycle, as will be explained in detail in the longer text.

The following description applies to both Fig. 1 and Fig. 2. The above description relating to Fig. 1 can also be applied to Fig. 2. It is clear from a comparison of the two figures that the same reference numerals have been used for the same parts in Fig. 1 and Fig. ^2. In Fig. 2, some elements of the system have been omitted for the purpose of simplifying the figure, such as the control member 22 and the valve 21, although it should be noted that these elements are necessary for carrying out the process of Fig. 2. In Fig. 2, which represents a preferred embodiment of the device according to the invention, the three zones of Fig. 1 are located in a single vessel, in contrast to Fig. 1, where these three zones are formed by three separate vessels. In Fig. 1, the lower gas line 14 is arranged between the lower zone 12 and the zone 11 forming the closing hopper, and the upper gas line 13 is arranged between the zone 11 forming the closing hopper and the upper zone 10. In Fig. 2, these gas lines are shown as a common part 26. It follows that in Fig. 2, the lower gas line 14 includes a part designated by the reference numeral 26 and the upper gas line 13 also includes a part designated by the reference numeral 26.

The transport of catalyst particles from the upper zone 10, representing the reaction zone, to the lower zone 12 without the use of valves, while maintaining the gas flow through the three zones, can be carried out using the five-stage cycle illustrated below. Three of these five stages are shown in Fig. 2. One cycle involves the transport of one batch of catalyst particles from the upper zone to the lower zone. Fig. 2A illustrates the first stage of this cycle, with the device in the so-called holding or preparation phase. Zone 11

CS 268 679 B2 forming the closing hopper is at this stage stretched to its maximum capacity by the catalyst. In the upper zone 10 forming the reduction zone there is a supply of catalyst, which catalyst remains in this zone until a suitable degree of reduction is reached. The upper transport pipe 15 for transporting particles and the lower transport pipe 16 for transporting particles are filled with catalyst, so that in this state there is no discontinuity in the mass of catalytic particles which fill the lower part of the upper zone 10, the upper transport pipe 15, the lower part of the zone 11 forming the closing hopper, and the lower transport pipe 16. The supply of catalyst in the upper zone 10 is supplemented by catalyst from the area of the regeneration device which is located above the upper zone (not shown). This figure shows the accumulation of catalyst in the lower zone 12.

During the first stage of the regeneration cycle, gas is conducted from the lower zone 12 to the zone 11 forming the closure hopper via the lower transport line 16. The pressure difference between the lower zone and the zone forming the closure hopper may, for example, range from 0.7 to 689.5 kPa or this pressure difference may be even greater, with the lower value of this pressure difference typically being greater than 34.5 kPa. The downward flow of catalyst particles from the zone 11 forming the closing hopper to the lower zone 12 is prevented at this stage of the process by the upward flow of gas through the lower transport pipe 16. At a high upward flow rate of gas and a relatively small height of the catalyst above the upper transport pipe 16, the catalyst particles in the lower transport pipe 16 are forced upward into the zone 11 forming the closing hopper, which causes a large increase in the gas flow and partial fluidization of the catalyst in the zone 11 forming the closing hopper. In the arrangement of the device as shown in the figure, a minimum length of the pipe 16 and at the same time a minimum height of the bed of particles immediately above this pipe must be created, with respect to the maximum necessary or required gas flow rate through the pipe 16. In the arrangement of the device, in which the said length of the pipe 16 and the height of the said bed are above this minimum level, the minimum required gas flow rate and the pressure difference between the two zones must be taken into account. For a given pressure difference, the longer the pipe, the lower the gas flow rate. In order to increase the gas flow rate for a given pipe length and a given pressure difference, it is possible to increase the diameter of the pipes.

The flow of catalyst from the upper zone 10 to the zone 11 forming the closing hopper in this stage does not occur (first stage) due to the fact that the level of particles in the zone 11 forming the closing hopper is at the level of the boundary region of the upper transport pipe 15. The reference numeral 27 indicates the boundary region or boundary level. It is clear from the illustration in this figure that in order for the catalyst to flow out of the pipe 15 (see FIG. 2A), this catalyst must be dispersed from this pipe at the level of the boundary region 27 and distributed outside this pipe. In this situation, it is not possible to use sufficient force to carry out this dispersion and distribution of the catalyst and therefore* in this embodiment the catalyst level never rises above the level of the boundary region 27, which was specified above.

During the second stage of this cycle (not shown), which may be referred to as the compression stage, the upper shut-off valve 18 is closed and the valve 19 in the lower gas line 14 is opened. This measure results in equalization of pressure between the zone 11 forming the closing hopper and the lower zone. In this stage, the internal pressure in the zone 11 forming the closing hopper is therefore increased, so that this pressure reaches a value higher than the internal pressure in the upper zone. After the pressurization of the zone forming the closing hopper is completed, the third stage of this cycle is initiated.

Figure 2B shows the later course of this third stage of the entire cycle, at which point the catalyst level in the zone 11 forming the closing hopper has now reached its normal lower level. This third stage can be referred to as the emptying phase of this cycle, at which point the catalyst is emptied from the closing hopper. The flow of solids from the upper zone to the zone 11 forming the closing hopper is prevented by the flow of gas in an ascending direction through the upper transport pipe 15, this situation

CS 268 679 82 ce It is the same as was stated in connection with the lower transport pipe 16. The level of catalyst particles in the zone 11 forming the closing hopper decreases as the solid particles flow through the lower transport pipe 16 into the lower zone 12. During this time interval, the gas that enters the bottom of the zone 12 via the pipe 20 flows through the lower gas pipe 14 through the lower shut-off valve 19 and is introduced into the zone 11 forming the closing hopper. During this time interval (third stage), the pressure in the lower zone and the pressure in the zone forming the closing hopper are essentially the same, although a small pressure difference may exist due to the gas flow through the lower pipe 14. .

From the above it is clear that the gas flow path during the execution of the second stage and the third stage is different from the gas flow path during the execution of the first stage, but in no case does this gas flow path occur, which would be caused by the transition from the first stage to the second stage. Arrows 28 indicate the gas flow path during the execution of the first stage and arrows 29 show the gas flow path during the execution of the third stage. It is also possible to program, if necessary, a slight delay in the closing of the upper shut-off valve 18 at the start of the execution of the second stage in an interval of several seconds or less. If at the same time a relatively slow opening of the lower valve 19 is ensured, then this measure will ensure that there are no significant transient disturbances in the flow (shock disturbances in the flow) due to manipulation of the valves.

When the level of catalyst particles in the zone 11 forming the closing hopper drops below a predetermined lower level, the fourth stage, referred to as depressurization, begins. As soon as the level of catalyst particles drops below a predetermined level, the lower level signal member 17 registers the absence of particles at this level, which represents the lower level of the closing hopper, and immediately transmits this signal to the control member 22. With the help of the control member 22, the lower shut-off valve 19 is closed and the upper valve 18 is opened, whereby the zone 11 forming the closing hopper is depressurized and the gas flow path changes so that it now coincides with the path during the first stage, the fourth stage ending when the pressure in the zone formed by the closing hopper is substantially equivalent to the pressure in the upper zone. In the fifth stage, the catalyst is fed into the zone formed by the closing hopper via the pipe 15. The fifth stage differs from the first stage in that during the first stage, the zone 11 forming the closing hopper is full and no catalyst flow occurs in this first stage either. During the fifth stage, the catalyst flows from the upper zone 10 into the zone 11 forming the closing hopper until the particle level reaches the limit level of the upper transport pipe 15, which completes this cycle and the process state returns to the holding phase represented by the first stage.

This five-stage cycle is repeated continuously during normal operation. For example, it may be assumed that the transport of one batch of catalyst from the upper zone 10 to the lower zone 12 may take approximately 50 seconds. The desired cycle repetition rate can be set by means of the control element 22, which is usually done manually, and a signal can be sent to initiate the entire cycle, i.e. to set the valves 18 and 19, so that the second stage can be started. In practical implementation of the process as described above, the maximum cycle repetition rate for a 50-second cycle is approximately once every 60 seconds. If the volume of the zone forming the closing hopper given by the normal maximum capacity range (the level at the boundary level given by the pipe 15) and the lower level signal element is taken as one unit volume, then the catalyst transport rate corresponds to a value of one unit volume per minute. When half the transport speed of this maximum value is required, this means that the control member 22 is set to start a new cycle every two minutes.

The control member 22 functions as a means for receiving the level signal from the lower level signal member 17, as a means for controlling the position of the shut-off valves 18 and 19, and as a means for setting the rate of repetition of the cycles. There are many different types of apparatus capable of performing the functions of this repw

CS 268 679 B2 of the lower level signal element 22, such as, for example, operational control computer systems or programmable controllers. It is also possible to provide for the performance of these functions by means of a cycle timer which provides signals for starting the cycle, and by means of a toggle switch controller which provides a response to the signal of the lower level signal element 17 for starting the fourth stage.

The length of the pipes 15 and 16 is very important from the point of view of the operation of the entire device, as already explained above. The range of permissible pressure difference between the zones depends mainly on the length of the particle column between the zones for a given diameter of the transport pipe and for a given type of particles. The length of the particle column between the individual zones can be defined as the length of the transport pipe plus the height of the particle bed above this transport pipe in a given zone, with the lowest point of the particle bed being at the bottom of the conical section of the given zone. In the case where the pressure difference is too large, the catalyst is carried from the transport pipe to the zone which is situated above this pipe. When verifying the processing procedure in the device according to the invention, a loud sound associated with particle entrainment was observed in experimental trials when increasing the pressure in a given zone, and this particle entrainment into the zone, which is located above this transport pipe, can also be easily detected visually. In cases where the pressure difference between the individual zones is too small, the gas flow rate is also small, which will result in poor catalyst regeneration. The catalyst column, through which the gas flows upward, can be considered as a resistance to flow, and the gas flow rate changes according to the pressure loss along this restriction due to this resistance or restriction.

In any design of such a device, the pressure difference across the closing hopper is usually known, since this value is usually independently determined by factors that have no relation to the system forming the closing hopper. So from the above it is clear that the starting point in the design of the said system are the values of the pressures of the pressure ranges in the upper zone and in the lower zone. The required maximum and minimum gas flow rates upward through the given zones and the required particle transport rate are also known, since these values are given by the process being carried out. According to these values, the length of the catalyst column and the diameter of the particle transport pipe are then designed. Furthermore, it is necessary to choose a balanced ratio between the length and diameter of this pipe in order to achieve the required gas flow rate simultaneously with the required instantaneous particle flow rate. Shortening the length while keeping other factors constant or increasing the diameter while keeping other factors constant will result in particle entrainment, if the change in these characteristic quantities is made to an excessive extent. Another very important feature in designing the apparatus according to the present invention is the length of each of the components which make up the total height of the particle column. The flow of gas through the transport pipe requires a considerably greater pressure difference per unit length than is the case for the same flow of particles immediately above the transport pipe. It should also be noted that the flow rate of the gas through the bed of particles must always be lower than the flow rate of the gas which causes the particles to fluidize. It will be very easy for those skilled in the art to select a mutually balanced ratio of all the variables and a way to adjust these variables to achieve good operation of the system. The principles by which the flow of solid particles is governed are sufficiently well known to those skilled in the art from the prior art that it is not necessary to discuss these factors here. Further information concerning the flow of solid particles can be found in United States Patent No. 2,851,401, which has already been cited above. However, this patent does not address gas flow. It should also be noted that in general, in the practical design of systems using solid particle flow, control experiments are performed to determine the flow characteristics of the particular solid particles used.

From the above it is evident that careful calculations must be made when designing the device according to the invention. At given internal pressures in the upper zone and in the lower zone, at given minimum and maximum gas flow rates, which are determined by the given process

CS 268 679 B2 sem, given the characterization of the gas and particles used and given the required particle transport speed within a certain range, it is necessary to carefully select the size of the zone forming the closing hopper when designing the said system, in particular the normal minimum and maximum volume that the given particles fill, the height of the bed in the zone forming the closing hopper above the transport pipe, the diameter of the transport pipes and the lengths of these transport pipes. It is obvious that there are also other parameters that must be determined when designing the device according to the said invention, such as the size of the gas pipe, and these parameters are the most important.

It is readily apparent from the illustration in Fig. 2 and from the indicated flow paths indicated by arrows 28, 29 and 32 in Figs. 2A, 2B and 2C, that both alternative flow paths occurring between the outlet of the conduit 20 and the top of the upper zone 10 result in substantially the same pressure drop at any time during the process. The pressure drop of the gas flowing through the catalyst in the large diameter areas of the apparatus is small compared to the pressure drop of the gas flowing through the transport conduits.

The device according to the invention can be characterized as a device with a controlled flow of solid particles at any time and place, since the flow rate of particles from the upper zone to the lower zone varies, as already mentioned above.

In order to carry out the processing procedure in this device according to the invention, it is necessary that the lower end of the transport pipe section has a smaller cross-sectional area for the flow of particles than the cross-sectional area of the remaining part of the pipe, this measure being referred to as a restriction. For example, it can be noted that in the case of a circular pipe, the internal diameter of the end of the pipe is smaller than the remaining part of the pipe, as is shown in Fig. 2A by reference numeral 27 indicating the boundary region. The purpose of this restriction is to keep the transport pipe filled with particles in the phase when the pressures in the zones between which this transport pipe is arranged are approximately equal. In the case where the pressures between the zones are not equal and the gas flows upwards, then the particles remain in the transport pipe, which is achieved by a suitable free length and diameter of the pipes 15 and 16, this solution adjusting the length of the particle column between the individual zones and preventing particle drift, as already mentioned above. In cases where this restriction is not implemented, the particles carried through the transport pipeline occur in a diluted phase, and when the pressure difference between the given zones is established, the transport pipeline is only partially filled with particles, which disrupts the course of the processing procedure in this device.

In an alternative embodiment of the device according to the invention, it is possible to use a high-positioned level sensor with which it is possible to reduce the level of particles in the zone 11 forming the closing hopper to a level that lies below the boundary area 27 of the upper transport pipe -15 for transporting. part^ifij. In cases where it is possible to adjust the position of this high-positioned level sensor within a certain range, it is possible to change the volume of the batch that is transported in the given device in this way. At the moment when the level of particles in the zone 11 forming the closing hopper reaches this high-positioned level, said high-positioned level sensor sends a signal to the control member 22 and this control member 22 closes the blocking valve 18 of the upper gas pipe 13, while the blocking valve 19 of the lower pipe 14 also remains closed. The gas flow path between the upper and lower zones then includes the upper transport pipe and the lower transport pipe, and the flow of particles through these two pipes stops. In the next phase, when it is necessary to start the work cycle after this holding stage, in which both blocking valves are closed, the blocking valve of the lower gas line is opened, thus starting the stage of emptying the closing hopper.

The reason for using this high level sensor instead of allowing the particle level to rise to the lower boundary area of the upper particle transport pipe is that the gas flowing upward into the pipe tends to stir the particles in the lower boundary area. This stirring of the particles can cause physical damage to them. Another way to solve this problem, if it occurs.

CS 268 679 B2 is to provide the lower end of this transport pipe with perforations. All or part of this gas will then flow through this perforation, thereby bypassing this portion of the catalyst and preventing mixing of the catalyst particles. The level of the catalyst particles cannot rise above the lower end of the perforated part of the pipe.

The device according to the invention can be used in practice for carrying out the most diverse processes, and in particular it can be used in hydrocarbon conversion processes, such as catalytic reforming, which has already been described in detail, in particular for the conversion of light paraffins into light olefins. With the help of this catalytic dehydrogenation treatment, it is possible, for example, to convert propane into propylene. In a further process of hydrocarbon conversion in the presence of a catalyst, it is possible to process light paraffins and/or olefins into aromatic hydrocarbons and hydrogen. The device according to the invention can be used for regenerating the catalyst that was used in the above-mentioned processes. As an example of a process other than a hydrocarbon conversion process for which the apparatus of the invention may be used, mention may be made of the treatment of a gas stream to remove a component by contacting the gas stream with a particulate solid material, such as the removal of sulfur dioxide from a flue gas stream by passing the flue gas stream through a bed containing a substance that binds sulfur dioxide, such as aluminum oxide containing copper in the form of spheres. However, the apparatus of the invention is preferably used in hydrocarbon conversion processes, and in particular in catalytic reforming processes, which are carried out in a moving bed.

Claims (1)

SUBJECT OF THE INVENTION Device for maintaining a continuous flow of gas in an upward direction through the lower zone and then the upper zone while simultaneously transporting particles downward from the upper zone to the lower zone, without contact of these particles with the means of transport and without influencing the internal pressure in the upper and lower zones, characterized in that it consists of an upper zone (10) containing particles, a lower zone (12) containing particles, and a zone (11) forming a closing hopper, located between the upper zone (10) and the lower zone (12), wherein a gas pipe (20) is introduced into the lower zone (12) for continuous supply of gas to the lower zone (12), between the upper zone (10) and the zone (11) forming the closing hopper there is placed an upper transport pipe (15), provided in its lower part with a constriction connecting the lower part of the upper zone (10) with the upper part of the zone (11) forming the closing hopper, where between the zone (11) forming the closing The hopper and the lower zone (12) are provided with a lower transport pipe (16), the lower part of which is narrowed, and connects the lower part of the zone (11) forming the closing hopper with the upper part of the lower zone (12), the upper zone (10) and the zone (11) forming the closing hopper being connected by an upper gas pipe (13), in which the upper .closing valve*”(-t^y»8SBWUť (11) forming the closing hopper and the lower zone (12) are connected by a lower gas pipe (14), in which the lower closing valve (19) is provided, and further in the zone (11) forming the closing hopper there is provided a sensor of the level signal member (17) connected to the regulating member (22) for receiving a signal from the level signal member (17) and further connected to the upper closing valve (18) and the lower closing valve (19)