RU2573013C1 - Chemically active filter element and method of making same - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: chemically active filter element, containing a chemically active material in the form of powder or granules, distributed on a frame made of a porous inert metal support placed in a porous casing. The chemically active material consists of a substance capable of changing the volume of the solid phase during operation. The porous inert metal support is made from a twisted metal wire with damping properties, where the distance between adjacent turns of the wire does not exceed the minimum particle size of the powder or granules of the active material. The active material is uniformly distributed across the cross-sectional area of the frame made of the porous inert support. A chemically active filter element is made by mixing the chemically active material with an auxiliary inert component to obtain a homogeneous mixture. The obtained mixture is used to mould a solid workpiece and placed in layers between layers of the porous metal support within the inert porous casing. The mixture is fed into the frame of the porous inert metal support under a load, followed by removal of the inert component.

EFFECT: ensuring stability of properties of the chemically active filter element, longer service life of the chemically active filter element, enabling full extraction of the chemically active material at the end of the service life.

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Description

The invention relates to the field of conducting heterogeneous chemical reactions in a gas-solid or liquid-solid system, including catalytic reactions on a catalyst surface, namely, to designs and methods for manufacturing nozzles of chemical reactors containing a filter element with a chemically active substance , distributed in a porous inert framework, and can find application in chemical technology, for example, in ion-exchange processes.

A description of the chemically active filter element is known [S.V. Lasankin. A method of manufacturing a porous material. Patent RU 2042392, IPC B01D 39/12, publ. 08/27/1995], in which the filter element contains chemically active metal particles placed between knitted nets of metal fiber assembled in a bag that is fastened by sintering under the action of a deforming load.

A method of obtaining a filter element consists in knitting knitted nets of continuous fibers, which by their mechanical characteristics can be knitted in a knitted way. Then discrete metal fibers or powder are applied to the mesh depending on the required properties of the material being manufactured. The application of discrete particles on a knitted mesh can be carried out by any known method, for example, air, liquid, gravity, etc. The uniformity of particle deposition over the area may vary depending on the required properties of the material being manufactured. After this, the nets with the particles deposited on them are collected in a bag, stacking them on top of each other. In this case, discrete metal particles can be applied to the grid with a change in the percentage of discrete particles and knitted nets over the area of the nets, and the formation of a packet of nets is made from nets with different percentages of discrete particles and knitted nets. Thus formed package is subjected to deformation and sinter. The bag may be deformed in the mold or in the rolls. Sintering is carried out in a non-oxidizing atmosphere, determined by the chemical composition of the sintered material. Sintering temperature depends on the required properties of the fabricated material and is in the range of 0.9-1.15 melting points of discrete fibers.

The disadvantages of the method include the fact that the mechanical strength of the filter element is provided by sintering at the melting temperature of chemically active metal particles, which leads to a change in their properties, in particular, chemical activity, due to interaction with residual aggressive gases of the atmosphere and with the material of the metal fiber. The second significant drawback of the described filter element is that the use of knitted grids and hardening sintering under load leads to the formation of a rigid structure that does not allow changing the volume of chemically active particles during operation without changing the porosity and permeability of the entire element. Carrying out a technological process that requires a stably constant flow rate of a gas or liquid reagent using filters, the porosity and permeability of which changes during operation, is impossible. Particles of a chemically active material sintered with a metal mesh that can change its volume during operation will crack and collapse, changing its chemical activity as juvenile surfaces form, which will affect the stability of a chemical reactor based on these filter elements.

In addition, it is important that particles of the reactive material are placed over the cross-sectional area of the filter element without monitoring uniformity, which can lead to a “leakage” of a gas or liquid reagent without contact with the reactive material involved in the target chemical reaction. An important circumstance is that the chemical active material or catalyst can be made of a substance that is subject to regeneration and / or accounting storage and use for other purposes, for example, in the case of using precious metals. The sintering method, which is used to reliably adhere a reactive material to a porous base and impart the necessary strength to the design of the filter element, makes it extremely difficult to extract the reactive material.

The closest technical solution to the proposed is the element of the catalytic nozzle and the method of its preparation [A.D. Simonov, N.A. Yazykov, V.N. Parmon, V.A. Yakovlev. The element of the catalytic nozzle, the method of its preparation (options) and the method of carrying out catalytic exothermic reactions. Patent RU 2383389, INC B01J 32/00. Publ. 03/10/2010, BI No. 7]. In this case, the concepts of “catalytic nozzle element” and “chemically active filter element” are similar in essence to the general process that takes place in them. In both cases, a gas or liquid phase passes through the element, and a chemical transformation (chemical reaction) occurs on the surface of the particles of a chemically active substance or catalyst. In this solution, the catalytic packing element comprises a porous metal support and a catalyst. The granules (particles) of the catalyst are embedded in the volume of the porous support, while both the porous support and the catalyst distributed therein are housed in a shell of a porous support. The porosity of the inert carrier reaches 95%.

A method of preparing an element of a catalytic nozzle includes the introduction into the pores of a metal catalyst carrier in the form of a suspension, paste, solution or mixture of catalyst components under the influence of vibration load. The obtained preform from a porous support and a catalyst precursor introduced into it is covered with a porous inert metal support from above and below, an element of a catalytic nozzle is pressed and calcined.

The formation of the catalyst in the volume of the porous metal carrier is carried out by introducing a precursor from it (for example, plasticized aluminum hydroxide, aluminosilicate, silica gel or clay as a pore-forming component mixed with a catalyst in the form of granules, or its components, a suspension of catalyst powder or direct vibrational incorporation of the catalyst powder / options /) under the influence of vibration load or pressing followed by calcination.

Foam metals, metal felt or metal wool are used as the porous metal support.

The disadvantage of the prototype is that the porous carrier, taken in the form of foam metal, has a low damping ability due to the high stiffness of the frame, which increases when pressing the workpiece. Moreover, if the material of the chemically active component of the filter element is able to change its volume during operation, then under the conditions of pinching of its particles in the rigid surrounding matrix, cracking and destruction of its particles can occur with a change in the specific surface of the chemically active element (catalyst), leading to a change in the chemical activity and permeability of the filter element. In the case of the use of metal felt or wool, their low damping ability should also be expected, and with an increase in the volume of the solid phase of the chemically active component (catalyst), its particles will condense the metal fiber of the felt or wool, reducing the initial porosity and permeability of the filter element. A decrease in the permeability of the filter element will lead to a decrease in the gas flow rate through it and to a violation of the stable technological regime of the chemical reactor, in which nozzles from the filter elements are used. The lack of control over the uniformity of catalyst penetration into the volume of the porous support, in whatever form, as well as the lack of control over the uniformity of the distribution of catalyst particles in suspensions, pastes, or mechanical powder mixtures of the catalyst components can lead to uneven distribution of the catalyst over the volume of the porous support, and the cross-sectional area of the filter element. The uneven distribution of the chemically active substance in the volume of the porous carrier of the filter element, especially in its cross section, can lead to a “leakage” of a gas or liquid reagent through the filter element without contact with the chemically active substance with the absence of a targeted chemical reaction in the local areas of the filter nozzles elements and the entire reactor as a whole.

The use of various variants of the porous carrier in the filter element according to the patent [RU 2383389] in the form of foam metal, metal felt or cotton wool in any case makes it difficult to completely remove the reactive material for regeneration and / or subsequent use for another purpose.

The problem solved by the invention is aimed at improving the stability of the properties of the active filter element with the possibility of changing the volume of the solid phase of the reactive material during operation, as well as the possibility of the most complete extraction of the active material for subsequent regeneration. The technical result of the invention is:

- ensuring the stability of the properties and chemical activity of the filter element;

- increase the service life of the chemically active filter element;

- the ability to fully extract expensive chemically active material at the end of its service life;

- reduction of economic costs for its operation.

To solve this problem and achieve a technical result, a group of inventions is claimed, which includes:

a chemically active filter element and

- a method of manufacturing a chemically active filter element.

In the inventive chemically active filter element containing a chemically active material in the form of powder or granules distributed over a skeleton of a porous inert metal carrier housed in a porous shell, it is new that the chemically active material consists of a substance capable of changing the volume of the solid phase over time operation, the porous inert metal carrier is made of twisted metal wire with damping properties, while the distance between adjacent turns of wire is not greater is the minimum size of the powder particles or granules of the reactive material and the reactive material is distributed uniformly over the cross-sectional area of the carcass of a porous inert carrier.

In the inventive method of manufacturing a chemically active filter element, which consists in mixing a chemically active material with an inert component with respect to it, forming a mixture of the active material and an inert component, introducing the mixture under the influence of a load into the frame of a porous inert metal carrier placed in a porous inert shell, with the subsequent removal of the inert component, new is that the mixing of the reactive material with the inert component is carried out to Acquiring uniform mixture and form it into a solid preform and the resultant preform in an inert porous shell is disposed between layers of inert porous metal support.

Ensuring the stability of the properties and chemical activity of the filter element is achieved by the fact that a twisted metal wire with a distance between the turns not exceeding the minimum particle size or granule of a chemically active material has spring properties and dampens the change in particle size of the active material when its volume changes during operation. At the same time, the porosity and permeability of the filter element is preserved, and the particles or granules of the reactive material retain their integrity, shape and specific surface area, which helps to increase the service life of the filter element.

Reducing the operating costs of the filter element is ensured by the possibility of the most complete extraction of the reactive material at the end of its service life for its subsequent regeneration. This result is ensured by the fact that a twisted metal wire is used as the porous inert metal carrier, which allows you to unravel the structure of the frame from the porous metal carrier and remove expensive chemically active material.

The uniform distribution of the active material over the cross-sectional area of the filter element due to the creation of a homogeneous mixture of the active material and auxiliary inert component, as well as the layered structure of the filter element in the direction perpendicular to the flow of a gas or liquid reagent, eliminates the “leakage” of the reagent without contact with chemically active material, which, in turn, also ensures the stability of the chemical activity of the filter element.

The uniform distribution of the active material over the cross-sectional area and the volume of the filter element is also ensured by observing the distance between the turns of the metal wire, not exceeding the minimum particle size or granule of the reactive material. This eliminates the possibility of moving particles of the active material between the turns of the metal wire and has a positive effect on ensuring the stability of the properties of the filter element.

In FIG. 1 is a schematic illustration of a design variant of a chemically active filter element.

In FIG. 2 shows a diagram of the technological assembly of a chemically active filter element.

The proposed chemically active filter element (Fig. 1) consists of the following components. Particles or granules of the reactive material 1 are distributed in a frame of a porous inert metal carrier 2 in the form of a compacted twisted wire enclosed in a porous inert shell in the form of metal nets 3 (from the ends) and a metal shell with holes 4 (along the side surface).

In the manufacture of a chemically active filter element (Fig. 2), a porous inert metal carrier 2 of twisted metal wire, a solid blank of a homogeneous mixture of particles of a chemically active material 1 and an auxiliary inert component 5 is placed inside a porous inert shell of nets 3 and shell 4. How option, between each set of layers of two parts of the porous carrier 2 and one preform with the active material 1 enclosed between them, a metal mesh similar to position 3 ( not shown), which is designed to facilitate the separation of layers during disassembly of the filter element and the extraction of chemically active material. The number of layers is selected based on the characteristics of the process, the design and parameters of the chemical apparatus of the packed type, which uses the proposed filter element. In the manufacture of the filter element, additional equipment is used, for example, in the form of a matrix 7 and a pan 8 with technological holes that serve to exit an inert auxiliary component when the blank is introduced into the volume of the porous carrier and heat treated under the load created by the punch (load) 6.

The inventive chemically active filter element as a nozzle in a chemical apparatus (for example, such as an ion exchange column) operates as follows. A liquid or gas reagent is supplied to the apparatus and enters from one of the ends of the porous shell 3, 4 into the filter element. When the reagent comes into contact with the surface of the particles of the reactive material 1, the target chemical reaction occurs. Next, the reagent enriched with the reaction product in the same phase state as the starting reagent enters the next similar filter element (if necessary).

Upon contact with a chemically active material, the starting reagent undergoes a change as a result of the target chemical reaction and is further enriched in the reaction product. The process is repeated on the remaining filter elements - nozzles. At the exit from the apparatus, the final target product is obtained, for example, a mixture of the starting reagent enriched with the reaction product in the desired ratio or a pure product of the target chemical reaction.

The inventive design of a chemically active filter element and its manufacturing method were implemented in the following examples.

Example. 1. To ensure uniform distribution of the active element over the cross-sectional area at a low content (less than 5 vol.%), The powder of a chemically active material 1, for example, electrolytic zirconium with a particle size of 100 to 400 microns, was mixed with an inert in relation to it and easily flammable substance 5 aluminum chloride of the qualification "osch" (especially pure) to a uniform state. The homogeneity of the mixture was judged by the parameters of the dispersion of the content of chemical elements in different parts of the sample mixture, determined by the data of x-ray spectral microanalysis. The resulting homogeneous mixture was pressed in the form of tablets with a diameter of 31 mm and a height of 5 mm to a relative density of 0.7-0.8. Two metal nets 3 of EI 708A-VI twill weaving steel according to GOST 6613-86 with a mesh size of 40 μm were laid at the bottom with a hole in the shell with slots 4 made of stainless steel 12X18H10T. Four layers of twisted wire 2 made of steel EI 708A-VI with a distance between the turns not exceeding 100 microns, which were preformed in the form of a round billet, were laid on the mesh 3. A compressed tablet made of a chemically active material (zirconium) 1 and an auxiliary inert substance (aluminum chloride) 5 was placed on a layer of twisted wire. Then, the next blank was laid from a twisted wire laid in a circle. In total, the assembly had four layers of compressed tablets placed between five layers of twisted wire blanks. Two nets 3 were laid on top of the last layer of twisted wire 3. After this, the entire technological assembly was placed in a matrix 7 mounted on a pallet 8 with holes, and a punch 6 was installed on top of the mesh, creating a vertical load P. The assembly was placed in a sealed apparatus, vacuum was carried out to residual pressure 10 ^-1 -10 ^-2 mm RT. century, and then heating and aging were carried out at a temperature of 180 ± 5 ° C for 2-4 hours with the aim of sublimation and removal of an auxiliary substance - aluminum chloride. Under the action of the vertical load P created by the gravity of the punch 6, as the excipient 5 is removed, the powder particles of the active material 1 fill voids evenly over the entire cross-sectional area in the wire frame 2.

After the operation to remove the auxiliary substance 3, if necessary, the assembly is additionally compacted to the desired height by creating a load on the punch 6. The compacted assembly is extruded, the ends of the split sleeve 4 are crimped to give cohesion and strength to the finished filter element.

Example 2. It is completely similar to example 1 except that as a chemically active material 1 was used fine titanium powder according to TU 1715-036-07623615-2004 grade A with a particle size of less than 40 microns. To prevent it from spilling down in the finished filter element, the distance between the turns of wire from steel EI 708A-VI, used as a porous frame 2, is reduced to 20-40 microns. In addition, the size of the grids 3 was reduced to 20 μm and their number was increased to 4 pieces above and below. Titanium powder, as well as zirconium powder, is active with respect to oxygen and moisture, and at temperatures above 300 ° C, it is also active with respect to nitrogen. In this regard, a chemically active filter element is used as a getter of aggressive gases and vapors, for example, during additional cleaning and drying of inert gases. Moreover, the higher the dispersion of the chemically active material, the higher its reactivity (chemical activity).

Claims (2)

1. A chemically active filter element containing a chemically active material in the form of powder or granules distributed over a skeleton of a porous inert metal carrier placed in a porous shell, characterized in that the chemically active material consists of a substance capable of changing the volume of the solid phase during operation , a porous inert metal carrier is made of twisted metal wire with damping properties, while the distance between adjacent turns of wire does not exceed the minimum the particle size of the powder or granules of the reactive material, and the reactive material is evenly distributed over the cross-sectional area of the frame from a porous inert carrier. 2. A method of manufacturing a chemically active filter element, which consists in mixing a chemically active material with an inert component with respect to it, forming a mixture of the active material and an inert component, introducing the mixture under the influence of a load into the frame of a porous inert metal carrier placed in a porous inert shell, subsequent removal of the inert component, characterized in that the mixing of the reactive material with the inert component is carried out until one the foreign mixture and form it in the form of a solid preform, and the resulting preform in a porous inert shell is placed between the layers of the porous inert metal carrier.

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