RU197030U1 - DEVICE FOR CARRYING OUT CATALYTIC PROCESSES IN THREE-PHASE SUSPENSION LAYER - Google Patents

Abstract

The utility model relates to apparatuses of the chemical and petrochemical industry and is intended for carrying out mass transfer processes in a system of suspension catalysis reactors and can be used, in particular, for carrying out the Fischer-Tropsch synthesis reaction in suspension reactors. The device for carrying out catalytic processes in a three-phase suspension layer includes a bubbling a column filled with a suspension of a nanosized catalyst in the liquid phase, a circulation line, a pipe for introducing the liquid phase into the column h Through a circulation line, an ejector for introducing a gas phase mounted at the bottom of the bubble column and connected to a gas phase inlet line and a circulation line, and a pipe for outputting reaction products. The circulation line is connected to the column through an overflow jumper with the possibility of overflow of the liquid phase. The ejector includes a housing with an expansion nozzle, a replaceable nozzle and located inside the housing. The nozzle and nozzle are in the mixing chamber of the liquid and gas phases, to which the nozzles for the input of these phases are connected. The ratio of the diameter of the nozzle and the inner diameter of the nozzle is 1:10, and the inner diameter of the nozzle and the diameter of the nozzle for introducing the liquid phase from the circulation line are approximately equal. On top of the nozzle in the widest part of its expansion, a scattering grid with a mesh size of 0.12 to 0.6 mm is fixed by means of a sealing ring. Technical result: providing intensive sparging with a given optimal size of the synthesis gas bubbles passing through the suspension catalyst layer. 4 ave., 5 ill.

Description

The utility model relates to apparatuses of the chemical and petrochemical industries and is intended for carrying out mass transfer processes in a system of slurry catalysis reactors and can be used, in particular, for carrying out the Fischer-Tropsch synthesis reaction in slurry reactors.

Bubbling suspension reactors (in the English literature - slurry bubble column reactor, SBR) and bubbling bed reactors (ebullated bed reactor, EBR) are widely known. Both types of reactors are hollow vessels filled with a suspension catalyst layer, in which gas in one mode or another sparges and differs primarily in the size of the particles used - tens of microns for the first type and about 1 millimeter for the second.

Existing bubble reactors for the implementation of three-phase suspension processes are distinguished by the following important structural components:

a) gas distribution device (dispersant) - a horizontal plate with holes located at the base of the column. With all the possible variations in the design of the holes, the purpose of this device is to ensure the formation of a bubble stream with the smallest and most uniform bubbles, which facilitates intensive mixing of the liquid medium with the catalyst particles contained in it and mass transfer between the latter and the gas flow, which is important for the effective implementation of catalytic processes of the named type. Also, this device should be selected so as to exclude a failure (by a known analogy with distillation column plates) of the liquid phase directly into the supplied gas stream;

b) a circulation line parallel to the main column, if for one reason or another it is necessary to ensure the flow regime of the reactor and the suspension. The circulation is provided by installing a pump of one design or another (because, when it comes to syntheses from CO and H2, the conditions for the occurrence of developed movement in the gas lift mode are practically unrealizable); in addition to circulation, the catalytic suspension in this line can undergo other operations (removal of spent / supply of fresh suspension, etc.).

A device for producing a catalyst suspension is known, including a housing, nozzles for introducing the starting components and the finished product, a vertical paddle slow-moving mixing device, on each blade of which two paddle elements are fixed, and a lateral high-speed mixing device in the form of disk activators (see.a. USSR 1775148 A1, IPC B01F 7/00, publ. 11/15/1992).

A disadvantage of the known device is the complexity of the design and the high cost of manufacture.

A device for producing a suspension of a catalyst is known, including a pipeline with ferromagnetic elements located in a rotating electromagnetic field of a generator - stator of a three-phase AC machine. The components of the suspension are mixed under the action of torque and magnetic field irregularities. The mixed and dispersed components of the suspension are discharged through a grating that protects the ferromagnetic elements of the device from removal (AS USSR 567481, IPC B01F 13/08, publ. 08/22/1977).

The disadvantages of the known device are the heating of the catalyst particles from eddy currents at an uncontrolled heating temperature, high energy consumption and lack of recirculation.

The closest to the claimed by the set of essential features and achieved technical result (prototype) is a device for carrying out catalytic processes, namely, Fischer-Tropsch synthesis, in a three-phase suspension layer in suspension reactors, including a bubbler column filled with a suspension of a nanoscale catalyst in a liquid phase, a pipe for entering the liquid phase, a device for introducing the gas phase into the column is a perforated dispersant installed at the bottom of the bubble column and connected with a line input of the gas phase, a circulation line connected to the column via an overflow jumpers, with overflow of the liquid phase, an ejector for the circulation of the liquid phase and outlet for the withdrawal of the reaction products. (M.V. Kulikova, AE Kuzmin, O. B. Chupichev, “Field simulation of bubbling in a Fischer-Tropsch synthesis reactor with a nanoscale catalyst,” Journal of Applied Chemistry. 2018.V. 91. Issue 4, p. 528-532)

The device allows to ensure the optimal size of the synthesis gas bubbles passing through the suspension catalyst layer, effective mixing and saturation of the suspension medium with reagents due to intensive bubbling, and as a result, provides a high conversion of raw materials and a high yield of reaction products.

The disadvantage of the described device is the unstable mode of bubbling with the formation of bubbles of sparging gas of different sizes, which is why the process requires constant monitoring and regulation. When large bubbles form, they agglomerate, and the productivity and completeness of the Fischer-Tropsch reaction decreases. With a small size of the bubbles, foaming of the liquid phase and violation of the bubbling regime occurs, which also worsens the performance of the process.

The objective of the utility model is to develop a device for carrying out catalytic processes in a three-phase suspension catalyst bed with circulation of the liquid phase without a pump, which ensures effective dispersion of the bubbling gas.

The problem is solved by the fact that a device for carrying out catalytic processes in a three-phase suspension layer is proposed, including a bubble column filled with a suspension of a nanoscale catalyst in the liquid phase, a circulation line connected to the column through an overflow jumper with the possibility of overflowing the liquid phase, a pipe for introducing the liquid phase into the column through the circulation line, the device for entering the gas phase, mounted at the bottom of the bubble column and connected to the line of input of the gas phase and a circulation line, and a pipe for outputting reaction products, in which the device for introducing a gas phase is an ejector including a housing with an expansion nozzle, a replaceable nozzle, and a liquid and gas phase mixing chamber, to which the nozzles are connected, located inside the housing between the nozzle and the nozzle for introducing the liquid and gas phases, and the ratio of the diameter of the nozzle and the inner diameter of the nozzle is 1:10, and the inner diameter of the nozzle and the diameter of the nozzle for introducing the liquid phase from the circulation line are approximately equal, top nozzle in its widest part by expansion of the sealing ring is fastened diffusing grid with a mesh size of 0.12 to 0.6 mm.

The technical result of using the utility model is to provide intensive bubbling with a given optimal size of the bubbles of synthesis gas passing through a layer of suspension catalyst.

The proposed model is presented in FIG. 1 where

1 - ejector

2 - bubble column

3 - circulation line

4 - gas phase input line

5 - pipe for the initial filling of the bubble column with a liquid phase and gas outlet.

6 - overflow jumper

The device consists of: a bubble column (2) connected to the circulation line (3) and the gas phase input line (4) through an ejector (1) made of stainless steel 12 × 18n10t) located at the bottom of the bubble column and also connected to the circulation line through the overflow jumper (6) located in the upper part of the device. At the top of the column (2) and the circulation line (3), a pipe (5) is installed that serves both for the initial filling of the device with a liquid phase and for the gas outlet from the device.

In FIG. 2 presents the design features of the ejector in the context:

7 - replaceable nozzle

8 - pipe input gas phase (ejection medium)

9 - pipe input liquid phase (ejected medium)

10 - ejector housing with an internal chamber for mixing liquid and gas phases

11 - expansion nozzle of the ejector

12 - diffusion grid

13 - a sealing ring

14 - reactor coupling

In FIG. Figure 3 shows the variants of the scattering grid depending on the cell size — from left to right, 0.6, 0.4, and 0.12 mm, respectively.

The ejector is structurally constructed according to the classical scheme and consists of a housing with an internal chamber for mixing liquid and gas phases (10) and an expansion nozzle (11), in which a gas-liquid flow is formed and ejected into the bubble column (2), a replaceable nozzle (7), an input line the ejection medium (8) into which the gas phase enters, the entry lines of the ejected medium (9) into which the liquid phase enters (suspension of the catalyst). On top of the nozzle (11) in the widest part of its expansion, a scattering grid (12) with a mesh size of 0.12 to 0.6 mm is fixed by means of a sealing ring (13). The ejector body (10) together with the scattering net (12) and the sealing ring (13) is fixed in the bubble column (2) with the help of a coupling (14).

The proposed utility model is made in glass for the possibility of visual control of the hydrodynamic situation (bubble sizes, turbulent phenomena, piston formation, etc.) using 12 × 18n10t stainless steel shutoff and connecting valves and is designed to carry out catalytic processes in a three-phase suspension layer and can be used in carrying out processes using vapor-gas bubbling in suspensions containing nanosized catalyst particles, in particular, when carrying out the synthesis reaction for Fischer-Tropsch in slurry reactors.

The utility model works as follows:

The suspension (liquid phase) (total volume of about 2.5 l) is loaded into the device through the pipe (5) at the top of the bubble column (2) either slightly higher or slightly lower than the level of the overflow bridge (6). The gas phase is fed - the raw material of the corresponding catalytic processes (overpressure up to 2 atm), with the calculated volumetric flow rate into the inlet port of the ejector medium (8) of the ejector (1). The gas phase leaves the nozzle (7) in the expansion nozzle (10) of the ejector (1) through the scattering grid (12). When the gas phase passes through a scattering grid (12), gas bubbles of an optimal given size are formed depending on the size of its cells. The sealing ring (13) fixes the scattering net (12) in a predetermined position and prevents the breakthrough of the gas phase into the column. The coupling (14) secures the ejector (1) with a scattering net (12) in the bubble column (2).

Then, the resulting gas phase bubbles enter the bubble column volume (2), dragging the liquid phase along through the liquid phase input line (9), where it enters from the circulation line (3). After bubbling in the column (2), the gas (gas phase) leaves the volume of the suspension layer and then is removed from the device through the pipe (5). The liquid phase from the column (2) constantly flows through the overflow bridge (6) into the circulation line (3), from where it is again ejected into the column, thus closing the circulation circuit.

The volumetric flow rate of the liquid phase is controlled by varying the gas flow rate (within the limits determined by the limitations of the simulated process).

The following examples illustrate the operation of the proposed utility model.

Example 1 (comparative)

In the proposed device, a catalytic process is carried out in a three-phase suspension layer using the example of a Fischer-Tropsch synthesis reaction using an ejector that circulates the liquid phase. At a volumetric flow rate of gas (gas phase) of 25, 50, and 100 nl / h (see, Fig. 4, from left to right, respectively) without a scattering grid, a bubbling regime occurs, which is characterized by the formation of large, heterogeneous in size “lens-like” bubbles, which at high gas speeds, they can occupy the entire cross section of the bubble column.

Example 2

When using a mesh with a mesh size of 0.6 mm (Fig. 3, left), the nature of the bubbling dramatically changes. Small gas bubbles of a close size — 7–12 mm, are formed depending on the gas flow rate, and the homogeneity of the bubbles in size and distribution in the cross-section of the bubble column with the gas flow rate is preserved.

Example 3

When using a scattering grid with a mesh size of 0.4 mm (Fig. 3, in the middle): the size of the bubbles decreases to 5-10 mm with a gas flow rate of 25 nl / h (Fig. 5, left). When the flow rate increases to 50 (Fig. 5, in the middle) and 100 nl / h (Fig. 5, to the right), the average bubble size decreases to 4-8 mm. Bubbles are evenly distributed over the cross section of the column, moreover, the homogeneity of the bubbles in size and distribution in the cross section of the bubble column with the gas flow rate is preserved ..

Example 4

When using a mesh with the smallest mesh size of 0.12 mm (Fig. 3, right), the bubbles are also evenly distributed over the column section, and the bubble homogeneity in size and distribution in the bubble column section is preserved with a change in gas flow. The size of the bubbles is approximately equal to that shown in example 3.

Claims (1)

A device for carrying out catalytic processes in a three-phase suspension layer, including a bubble column filled with a suspension of a nanoscale catalyst in the liquid phase, a circulation line connected to the column through an overflow jumper with the possibility of overflow of the liquid phase, a pipe for introducing the liquid phase into the column through the circulation line, a device for the input of the gas phase, installed at the bottom of the bubble column and connected to the input line of the gas phase and the circulation line, and a pipe for outputting reaction products, characterized in that the device for introducing a gas phase is an ejector comprising a housing with an expansion nozzle, a replaceable nozzle, and a chamber for mixing liquid and gas phases located inside the housing between the nozzle and nozzle, to which nozzles for introducing liquid and gas phases are connected moreover, the ratio of the diameter of the nozzle and the inner diameter of the nozzle is 1:10, the inner diameter of the nozzle and the diameter of the nozzle for introducing the liquid phase from the circulation line are approximately equal, and on top of the nozzle in the widest part of it expansion by means of a sealing ring a diffusing grid is fixed with a mesh size of 0.12 to 0.6 mm.

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