RU194072U1 - APPARATUS FOR PUNCHING THE CARRIER OF THE ISOMERIZATION CATALYST - Google Patents

Abstract

The apparatus for calcining carriers of C-fraction isomerization catalysts and carriers of other isomerization catalysts has at least five separate thermal zones — preheating, drying, heating, calcining, cooling, separated by internal devices, the internal devices being a complex of transfer pipes providing movement the carrier between the zones under the influence of gravity and preventing the preferred flow of the coolant gas from one zone to another, and each zone is warm New processing of granular material has an individual input and output coolant. Precise temperature control in the thermal zones is carried out by mixing the heat carrier gas and the diluent gas entering the input of each zone. The temperature difference in the heat treatment zones is provided at a level of no more than 5 ° C. The distribution of the gaseous coolant in the volume of the carrier of the isomerization catalyst is carried out due to the gas distribution device, which is a horizontally arranged system of conical hollow channels penetrating the carrier layer. The apparatus contains internal devices separating the heat treatment zones of the granular isomerization catalyst carrier and consisting of a distribution plate formed by gas-tight funnel-shaped segments overlapping the cavity of the cylindrical casing in cross section. 5 cp crystals, 1 tablet, 2 ave., 4 ill.

Description

The technical solution relates to the production technology of carriers of C ₇ fraction isomerization catalysts and carriers of other isomerization catalysts, in particular, to the design and functioning features of a continuous shaft drying and calcining apparatus with a dense dispersed layer of granular material moving under gravity, preferably an isomerization catalyst carrier in accordance with with patent No. 2401162 describing a method for preparing a carrier for a light benz isomerization catalyst other fractions, including aluminum oxides, zirconium, characterized in that the carrier further comprises tungsten oxide and optionally titanium oxide and / or manganese oxide, and is a composition of oxides: aAl ₂ O ₃ ⋅ bZrO ₂ ⋅ cWO ₃ ⋅ dMO ₂ , where M - Ti, and / or Mn; a = 0.05-0.3; b = 0.6-0.9; s = 0.005-0.15; d = 0 or d = 0.001-0.015; a a + b + c + d = 1.

The working volume of the continuous shaft mine described in this patent is divided into at least 4 zones, in a preferred embodiment of the invention, into 5 zones, characterized by heat treatment conditions and residence time of the granular material. The separation of zones in accordance with the utility model is carried out using internal devices of a special design that impede the preferred penetration of the coolant from one zone to another, as well as by organizing an individual input of the coolant into each zone, which facilitates a clear separation of the heat treatment of granular material into zones and achieve the required quality indicators of calcined granular material. To ensure the required thermal regime in each zone of the shaft furnace according to the present invention, the use of a heat carrier gas with temperature control at the entrance to the zone due to mixing with a diluent gas in a certain proportion is provided.

The calcination stage is an important operation of the catalyst carrier production technology, since at this stage, as a result of phase, polymorphic and chemical transformations, the necessary carrier structure is formed, which determines its physicochemical properties and subsequently the catalytic activity and performance of the final catalyst.

The vast majority of isomerization catalyst supports are metal oxides, semimetals and their combinations (alumina, zirconia, silica gels, zeolites, etc.) having many polymorphic modifications. The main influence on the formation of the carrier in one or another structural modification is exerted by the heat treatment mode. In this regard, precise control of the drying and calcining temperatures allows achieving the required physicochemical characteristics of the isomerization catalyst carrier. A particular influence on the physicochemical characteristics of the isomerization catalyst carrier is exerted by the uniformity of heating, namely, providing a temperature difference in the layer of granular material of not more than 5 ° C.

The final heat treatment of the isomerization catalyst carrier is carried out in a calcining apparatus, often including a drying step. There are various types of drying and calcining apparatuses that differ in design (mine, drum, tunnel), the principle of operation (continuous or periodic operation). Mine-type drying and calcining apparatuses are simple and reliable in operation, as well as a reduced load on the carrier granules in comparison with other similar apparatuses, which allows to reduce the formation of substandard product in the form of dust and crumbs.

A known method of calcining a catalyst for the oxidation of sulfur dioxide in a shaft furnace (copyright certificate No. 978914). In accordance with the invention, the granular catalyst is calcined in a stream of gaseous heat carrier with a temperature of 590-600 ° C under a pressure of 1.2-1.5 atm. Obtained by burning a gas-air mixture. The shaft furnace is divided into a drying zone and a calcination zone, with each zone having independent fresh input and output of spent heat carrier, due to which separation of the heat treatment conditions of the catalyst into zones is achieved. A design feature of the shaft furnace described in the method is the organization of the introduction of coolant gas into the calcined catalyst layer at an angle of 45-50 ° through the distribution grid, which contributes to the uniform distribution of the coolant gas in the catalyst layer and to improve the uniformity of calcination. The process at a temperature of 590-600 ° C, a pressure of 1.2-1.5 atm. and the flow of coolant at an angle of 45-50 ° can significantly reduce the duration of calcination of the catalyst, increase the strength of the granules and increase the activity of the catalyst.

The disadvantage of the invention is the absence of a stage of pre-heating of the catalyst before the stages of drying and calcination, which leads to a toughening of the thermal treatment of the catalyst due to the increase in heat stroke, leading to the destruction of the granular material, as well as the conditional separation of the zones of heat treatment, which does not allow to clearly separate the heat treatment of the catalyst and ensure uniform heating of the catalyst layer.

In another invention (patent number SU 1366830 A1) describes the device and principle of operation of a shaft furnace for the production of catalyst carriers containing burnable pore-forming additives. According to the invention, the shaft furnace is divided into 6 zones, 2 of which are intended to create favorable conditions for burning the burn-out component, and 4 zones, respectively, for heating, calcining, holding and cooling the carrier. The pore-forming additives burning chamber is located obliquely and connected to the preheating chamber following it and a chimney that discharges gas from adjacent zones, thereby preventing gas flows from mixing in the zones and contributing to the separation of the temperature regimes of the burning zone and the heating zone.

From the copyright certificate No. SU 141171, a multi-zone shaft furnace design is known containing heating, calcining and cooling zones located in one common shaft having by-pass channels that allow controlling the supply of flue gases to the calcining zone, thereby achieving the possibility of adjusting the temperature in the calcining zone.

The temperature in the calcination zone is controlled by changing the gas flow through the bypass pipes heating the granular material heating zone, and therefore the change in the flue gas flow through the calcining zone will entail a change in the temperature regime of the heating zone.

The disadvantage of the design of the shaft furnace described in the patent is the high mutual dependence of the thermal conditions of the heating and calcining zones and, as a consequence, the inability to ensure the constancy of the temperature regime in the zones and uniform heating of the dense layer of granular carrier.

Also known is the invention (copyright certificate No. SU 1712754 A1) relating to the technique of carrying out thermal processes in moving dispersed media, mainly granular catalysts and their supports, providing an increase in the uniformity of processing of the calcined material due to the organization of many local alternating gas flows that improve heat transfer in the layer. The described effect is achieved due to the formation of thermal pressure by two electric heaters located in the walls of the shaft and inside the axial tubular insert and the formation of pulsating gas movement in the working volume of the shaft furnace by means of a pulsator pump.

The disadvantages of the known device is the insufficiently effective output of gaseous products of calcination of the catalyst carrier due to the lack of gas flow through the layers of granular material. The internal volume of the shaft furnace is conditionally divided into 3 zones: heating, heat treatment and cooling. In this regard, it is not possible to independently control the temperature in the zones and ensure uniform heating of the carrier layer.

Closest to the proposed invention is the copyright certificate SU 392315 A1, relating to the technique of firing polydisperse materials, which is a shaft furnace divided by gratings into two heating zones, a firing zone and a cooling zone, as well as including a hot cyclone. In accordance with the invention, the heating zone is separated from the burning zone by a blank partition. The calcined material is moved from the heating zone to the firing zone using an external transfer pipe. The polydisperse material is heated by burning hydrocarbon gas supplied to burners installed on the grill of the firing zone, bordering the cooling zone. Gas from the calcination zone then enters a hot cyclone, where entrained particles of polydisperse material are released. The gas exiting the hot cyclone passes through two zones of heating the polydisperse material in series and then leaves the furnace.

A disadvantage of the invention is the burning of hydrocarbon gas directly at the entrance to the firing zone, and therefore the range and accuracy of temperature control of the calcination of the material are reduced, as well as the uniformity of heating of the catalyst carrier. In addition to this, it is not possible to control the temperature of the flue gases at the entrance to different heating zones.

A common drawback of the described examples is the lack of technical ability to precisely control the heat treatment of granular material over temperature zones, as well as the lack of control of the uniformity of heating of the calcined support, which during calcination makes it difficult to form a porous structure with desired properties and to produce a high-quality carrier.

In the process of heat treatment of the isomerization catalyst carrier, the most important role is played by the temperature regime of drying and calcination, the composition of the gas phase in each zone, and the length of the catalyst carrier in the temperature zones.

The studies of the authors of the present invention have established the influence of the uniformity of the temperature field of the catalyst carrier layer in the heat treatment zones of the drying-calcining apparatus and the accuracy of temperature control on the structure characteristics and physical properties of the isomerization catalyst carrier.

The technical problem solved by this technical solution is to create conditions for the heat treatment of the granules of the isomerization catalyst carrier, ensuring the production of the isomerization catalyst carrier with a given structure and physical properties.

The technical result in relation to the device is to create a drying and calcining apparatus of a mine type of continuous operation, including at least the stages of preheating, drying, heating, calcining and cooling, the distinctive features of which are the special design of internal devices that allows for the efficient separation of the zones of heat treatment of the carrier catalyst, as well as the distribution system of the coolant gas in the layer of the processed granular material, -governing differential temperature to provide a layer of not more than 5 ° C and not create an obstacle movement granular material vertically downward under gravity.

The optimal result of processing the isomerization catalyst carrier is achieved by using:

- internal devices separating the heat treatment zones of the granular isomerization catalyst carrier and consisting of a distribution plate formed by gas-tight funnel-shaped segments overlapping the cavity of the cylindrical casing in cross section;

- transfer pipes connected to the lower ends of the funnel-shaped segments and providing flow of the granular carrier between the heat treatment zones vertically downward by gravity, as well as preventing the predominant penetration of coolant gases from one zone to another;

- a gas distribution system consisting of a distribution chamber and a gas distribution device that provides for the formation of a uniform flow of a heat carrier gas of a given temperature through a cylindrical dense layer of isomerization catalyst carrier.

A general view of the proposed installation is shown in FIG. 1, where the following notation is used.

1 - Distribution plate;

2 - Transfer pipes;

3 - gas distribution device;

4 - distribution chamber;

5 - refrigerator;

6 - Unloading device;

7 - Cylindrical shell

8 - A shell of a square section;

9 - Connecting section;

10 - The union for loading a product;

11 - The union for unloading a product;

12 - The union for the entrance of the heat carrier with a temperature of 50-300 ° C;

13 - The union for the entrance of the heat carrier with a temperature of 100-400 °;

14 - The union for the entrance of the heat carrier with a temperature of 350-700 ° C;

15 - The union for the entrance of the heat carrier with a temperature of 400-850 ° C;

16 - The union for the exit of the coolant from the heating zone;

17 - Fitting for the exit of the coolant from the drying zone;

18 - Connection for the exit of the coolant from the heating zone;

19 - Fitting for the exit of the coolant from the calcination zone;

20 - Fitting for air inlet into the refrigerator;

21 - The union for an exit of air from the refrigerator;

22 - The union for the thermocouple;

23 - The union for air inlet;

24 - receiving hopper;

25 - Heat carrier gas;

26 - Gas diluent;

27 - Exhaust gas from the heating zone;

28 - Waste gas from the drying zone;

29 - Waste gas from the heating zone;

30 - Exhaust gas from the calcination zone;

31 - Coolant;

32 - Spent cooling agent.

In general terms, the present utility model describes a device that allows for multi-stage sequential heat treatment of a pre-dried granular isomerization catalyst support, which is an elongated cylindrical column divided in height into 5 thermal zones:

- preheating zone;

- drying zone;

- heating zone;

- calcination zone;

- cooling zone.

In a preferred embodiment of the method, said thermal zones differ in height and operating conditions. The separation of the specified heat treatment zones of the carrier is carried out using internal devices, which are a set of transfer pipes that ensure the movement of the carrier between the zones under the action of gravity and prevent the preferred flow of heat carrier gas from one zone to another.

Each of these thermal zones is equipped with an independent inlet and outlet of a heat carrier gas and a gas distribution system to create a unique thermal and gas-dynamic treatment regime for a dense layer of granular material, which allows to ultimately obtain an isomerization catalyst carrier that meets the required characteristics.

In a preferred embodiment of the method, the heat carrier gas is introduced through the nozzle of the distribution chamber connected to the gas distribution device located in the carrier layer and which is a horizontally arranged system of conical hollow channels providing uniform effective axial introduction of the coolant into the granular material layer.

The cooling zone of the granular carrier is equipped with a heat exchanger, with the help of which the granular carrier is effectively cooled to the temperature necessary for the unloading and packing operation.

In FIG. 1 shows a diagram of a drying and calcining apparatus.

In Fig.2 shows a horizontal section of the drying zone of the drying and calcining apparatus (Fig. 1).

In FIG. 3 shows a vertical section of the drying and heating zones of the drying-calcining apparatus (Fig. 1).

In FIG. 4 shows a horizontal section of the cooling zone of a drying and calcining apparatus (Fig. 1).

The figure 1 presents a diagram of a technological apparatus (device) intended for carrying out operations of drying and calcining a carrier of an isomerization catalyst in accordance with the proposed technical solution. The main element of the shaft furnace is a welded cylindrical casing, in which there are heating, drying, heating and calcining zones. The zones are separated from each other by internal devices consisting of a distribution plate 1 and transfer pipes 2. The segment of the shaft furnace, representing the cooling zone, is combined with the cylindrical part of the apparatus by the connecting section 9 and is made in the form of a shell of square section 8 with the air cooler 5 placed inside the tube bundle .

In accordance with the scheme, the pre-dried granules of the isomerization catalyst carrier are introduced into the upper section of the drying and calcining apparatus 7 through the nozzle 10. The internal device of the apparatus 7 is arranged in such a way as to ensure a continuous flow of the granular carrier down through the entire volume.

In a preferred embodiment of the invention, the material to be processed falls on the distribution plate 1 of the receiving hopper 24, which communicates with the pre-heating zone by a plurality of transfer pipes 2, providing uniform movement and distribution of the granules of the processed material. Next, the carrier of the isomerization catalyst leaves the outlet openings of the transfer pipes 2 and enters the free volume of the preheating zone, in which a continuous cylindrical layer of granular carrier is formed. The temperature in each zone is controlled by four thermocouples 22 located in the layer of granular material

In the preheating zone, the carrier granules are subjected to heat treatment at a temperature of 50-300 ° C with a heat carrier gas 25, the temperature of which is controlled by mixing with a diluent gas 26. The moisture content in the carrier gas 25 is from 100 to 15000 ppm, in a preferred an embodiment of the invention is from 7000 to 12000. The moisture content in the diluent gas 26 is from 10 to 10,000 ppm, in a preferred embodiment of the invention is from 3,000 to 8,000. The heat carrier gas passes axially from the cylindrical layer of the catalyst support. The heat carrier gas is introduced into the preheating zone through the nozzle 12 connected to the distribution chamber 4 and the gas distribution device 3, which is a system of channels located in the volume of the granular carrier and ensuring uniform distribution of the gas flow in the layer. The temperature difference in the dense layer of the granular support of the isomerization catalyst is controlled and is not more than 5 ° C. The spent heat carrier gas 27 after contact with the particles of the granular carrier in a dense layer passes to the upper part of the preheating zone, not filled with granular material, and then leaves the apparatus through the nozzle 16.

The preheating zone from below is limited by a distribution plate 1, which forms the carrier flow through the transfer pipes 2, which ensure a uniform continuous flow of the isomerization catalyst carrier between the zones and prevent the predominant transfer of heat carrier gases from one zone to another. The pre-heated catalyst carrier by means of movement along the transfer pipes 2 under the action of gravity then enters the drying zone, where it is subjected to heat treatment at a temperature of 100-400 ° C. Temperature control in the drying zone is carried out automatically using valves located on the supply lines of the coolant gas 25 and diluent gas 26 in front of the mixing unit. The heat carrier gas is introduced into the drying zone through a nozzle 13 connected to a distribution chamber 4 provided with a system of gas distribution channels 3 located in the volume of the catalyst carrier and ensuring the formation of a uniform gas flow through a dense cylindrical layer of granular material. The temperature difference in the dense layer of the granular support of the isomerization catalyst is controlled and is not more than 5 ° C. The drying gas, which has absorbed the moisture released from the catalyst carrier, enters the upper part of the drying zone, which is not filled with granular material, and then leaves the apparatus through the nozzle 17.

The dried granular carrier enters the receiving part of the transfer device — distribution plate 1 and, moving under the action of gravity, enters the annular layer of the heating zone preceding the calcination stage. The heat carrier gas enters through the nozzle 14 into the distribution chamber 4 of the heating zone, from where it flows through the gas distribution channels 3 into the moving cylindrical layer of the carrier from the bottom up, heating the granules of the processed material to a temperature of 350-700 ° C. The temperature difference in the dense layer of the granular support of the isomerization catalyst is controlled and is not more than 5 ° C. After passing through a layer of granular carrier, the waste heat carrier gas 29 enters the free space of the heating zone and then is removed through the nozzle 18.

The carrier, which has been pretreated in the heating zone, is received by the distribution plate 1, and then through the transfer pipes 2 it enters the volume of the calcination zone, forming a continuous cylindrical layer of material. The granular support in the calcination zone is heated to a temperature of 400-850 ° C by the heat carrier gas entering the calcination zone through the nozzle 15 connected to the distribution chamber 4, which distributes the heat carrier gas through the gas distribution channels 3 penetrating the moving layer of the calcined support. The temperature difference in a dense layer of granular isomerization catalyst carrier is not more than 5 ° C. The spent gaseous coolant 30, passing through a layer of granular material, enters the free space of the calcination zone and then is removed through the nozzle 19.

Next, the calcined granular carrier through the pretreatment pipe 2 is sent to the cooling zone, which is a shell-and-tube refrigerator 5, the cooling agent 31 in the preferred embodiment of the invention is the air pumped by the fan into the tube space through the nozzle 20. The isomerization catalyst carrier moves between the tubes of the refrigerator, cooling to a temperature of 50 -60 ° C at the exit of the zone, after which it is received by the unloading device 6 and then leaves the drying and calcining apparatus through the nozzle 11. Per pad temperature in the dense layer of granular carrier isomerization catalyst is not more than 5 ° C. The spent cooling agent is discharged from the refrigerator through the fitting 21.

The proposed design of the shaft furnace completely takes into account the technological features of the processing of granular supports of C ₇ fraction isomerization catalysts and other isomerization catalysts, the basis for which in the preferred embodiment of the invention is a mixture of aluminum and zirconium oxides. In a more preferred embodiment of the invention, the supported carrier comprises alumina, as well as metals such as zirconium, tungsten, titanium, manganese, germanium, tin.

A distinctive feature of the invention is the ability to precisely control the heat treatment conditions in each zone of the proposed drying and calcining apparatus, as well as to ensure high uniformity of the heating of the carrier layer in order to obtain an isomerization catalyst carrier that demonstrates the best physical properties and is the basis for the production of the most active sample of industrial isomerization catalyst.

The invention is illustrated by the following examples.

Example 1

The extrudates of the carrier of the isomerization catalyst With ₇ fractions subjected to heat treatment, are made in accordance with the formula:

аАl ₂ O ₃ ⋅ bZrO ₂ ⋅ сWO ₃ ⋅ dMO _n ,

where M is Ti, and / or Mn;

a = 0.25;

b = 0.68;

s = 0.057

d = 0.013,

a a + b + c + d = 1.

In the drying and calcining apparatus, the extrudates are pre-heated to a temperature of 130 ° C for 1 hour, dried at a temperature of 130 ° C for 11 hours, heated to a temperature of 830 ° C for 5 hours, calcined at a temperature of 830 ° C for 4 hours and cooling to 50 ° C for 2 hours.

The drying and calcining apparatus according to Example 1 does not have internal devices allowing to separate the heat treatment zones of the carrier; the heat carrier gas is introduced perpendicular to the flow of the granular catalyst carrier. The temperature difference in the heat treatment zones is 10-30 ° C.

Example 2

A method of preparing extrudates of the carrier is carried out according to example 1.

In the drying and calcining apparatus, the extrudates are preheated to a temperature of 130 ° C for 1 hour, dried at a temperature of 130 ° C for 11 hours, heated to a temperature of 830 ° C for 5 hours, calcined at a temperature of 830 ° C for 4 hours and cooling to 50 ° C for 2 hours.

The drying and calcining apparatus of example 2 includes internal devices in accordance with this technical solution. The temperature difference in the heat treatment zones is not more than 5 ° C.

The same amount of active metal was deposited on the prepared samples of isomerization catalyst support carriers. The samples that passed the impregnation stage were dried at a temperature of 150 ° C for 8 hours and calcined at a temperature of 550 ° C for 6 hours. The stages of drying and calcination of the catalyst carrier were carried out in a stream of air with a moisture content of not more than 5 ppm.

Samples of isomerization catalysts were tested in the process of isomerization of C ₇ fraction hydrocarbons in a flow-through pilot plant. The volume of catalyst loaded into the reactor was 4 cm ³ . The preparation of the catalyst for tests to determine the activity was to restore dried hydrogen in a stream at a temperature of 100-150 ° C for 1-2 hours.

The isomerization process was carried out at a temperature of 170 ° C, a pressure of 2.5 MPa, a molar ratio of hydrogen: feed, equal to 6: 1, and a volumetric feed rate of 2.5 h ^-1 . As raw materials used n-heptane. The reaction products were analyzed by gas-liquid chromatography on a stream using a capillary column with a liquid phase.

Claims (6)

1. An apparatus for calcining a granular isomerization catalyst carrier, which is a shaft-type drying and calcining furnace, characterized in that the apparatus has five separate thermal zones — preheating, drying, heating, calcining, cooling, separated by internal devices, the internal devices being a complex of transfer pipes, providing carrier movement between the zones under the action of gravity and preventing the flow of heat carrier gas from one zone to another . 2. The apparatus according to claim 1, characterized in that each heat treatment zone of the granular material has an individual input and output coolant. 3. The apparatus according to claim 1, characterized in that the precise temperature control in the thermal zones is carried out by mixing the heat carrier gas and the diluent gas entering the input of each zone. 4. The apparatus according to claim 1, characterized in that the distribution of the gaseous coolant in the volume of the carrier of the isomerization catalyst is carried out due to the gas distribution device, which is a horizontally arranged system of conical hollow channels penetrating the carrier layer. 5. The apparatus according to claim 1, characterized in that the temperature difference in the heat treatment zones is provided at a level of not more than 5 ° C. 6. The apparatus according to claim 1, characterized in that it contains internal devices separating the heat treatment zones of the granular isomerization catalyst carrier and consisting of a distribution plate formed by gas-tight funnel-shaped segments overlapping the cavity of the cylindrical casing in cross section.

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