RU2102120C1 - Device for cleaning of inert gas - Google Patents

Abstract

FIELD: devices for cleaning inert gases (krypton, xenon, argon and others) from gaseous impurities such as nitrogen, oxygen, hydrogen, carbon dioxide gas, etc by their absorption with solid absorbent (sponge titanium or other getters) in chemical, metallurgical, mechanical engineering and other industries. SUBSTANCE: device includes heatproof body with removable cover and bottom in which internal cylindrical retort with perforated bottom is installed. Internal cylindrical retort is located coaxially in external retort to form annular gap for passage of cleaned gas. External retort lower half is filled with alternating layers of solid absorbent with packing and without it. Packing is presented in the form of left-hand or right-hand spiral from metal band with absorbent poured into slotted gaps. Heater encased in its own casing is located inside device body, on external surface of external retort. Body also has heat exchanger mounted in upper half of internal retort and presents shielded heat insulator with trays polished in direction of gas motion. Body has process branch pipes located on external retort surface protruding above body cover. EFFECT: higher cleaning depth of inert gas to 0.5x10^-4-1x10^-4 % vol, reduced power consumption, possibility of cleaning of inert gases of particular value, simple maintenance and operation, reduced overall dimensions, provision of ecological safety in operation. 2 cl, 1 dwg

Description

 The invention relates to devices intended for the purification of an inert gas (for example, krypton, xenon, argon, etc.) from gaseous impurities such as nitrogen, oxygen, hydrogen, carbon dioxide, hydrocarbons, etc. by absorbing the latter with a solid absorber (sponge titanium or another getter) and can be used in chemical, metallurgical, engineering and other industries where pure inert gases are obtained for use in medicine, lighting engineering, nuclear physics, etc.

 A device for cleaning inert gas from impurities, equipped with technological pipes and a refrigerator, containing a vertical insulated housing with a lid and a bottom, in which a heater is installed and an inner cylindrical retort (container) with a perforated bottom filled with a solid absorber. The bottom of the body is placed on risers with the ability to move. The device is equipped with an inverted cone, the base of which is connected to the perforated bottom of the retort, and the top with a gas inlet pipe. The temperature regime in the device is controlled by thermocouples (see ed. St. USSR N 867402, class B 01 D 53/00, decl. 17.02.76, publ. 30.09.81 g).

 A disadvantage of the known device is the uneven distribution of temperature in the layer of the absorber, which leads to inefficiency of cleaning and significant energy consumption.

 In addition, the absence of a lid on the retort causes contamination of the purified gas with gaseous components sorbed by the porous ceramic of the heat insulation of the housing, which aggravates the inefficiency of cleaning.

 The closest in technical essence and the achieved result to the claimed invention is an inert gas purification device equipped with technological nozzles (gas inlet and outlet nozzles) and a heat exchanger (countercurrent type "pipe in pipe"), including a thermally insulated body with a removable cover and bottom, in which a heater and an inner cylindrical retort (tank) with a perforated bottom filled with a solid absorber are installed. The device is equipped with a conical distribution chamber connected to technological branch pipes. In the tank there are horizontal and cylindrical partitions. The heating of the heater and the solid absorber is controlled by thermocouples (see ed. St. USSR N 1049089, class B 01 D 53/04, decl. 11.06.82, publ. 23.10.83 g).

 The described device allows to reduce the gradient of the temperature fields of the absorber (uneven temperature distribution), reduce energy consumption and increase the depth of purification of inert gas (neon or argon) from oxygen and nitrogen.

 However, the known device does not allow to obtain a particularly pure inert gas due to the possibility of contamination of the gas being cleaned through the thermocouple inlets, and valuable gas is leaking.

 In addition, deep cleaning of inert gases is problematic due to the short gas path in the known device, insufficient heating of the gas to be cleaned before entering the retort (the absence of any contact of the gas to be cleaned with the heater) and the presence of some unevenness in the temperature fields of the absorber (in the central and peripheral zones).

 The disadvantages of the known device include significant energy costs due to the use of a tube-in-pipe heat exchanger for heating the source gas (cooling the purified gas), the heat exchange of which is ineffective.

 In addition, there is a complex indirect heat exchange between the heater and the gas to be cleaned through the inert gas layer, the retort wall and the absorber layer.

 Also, the known device is not applicable for the purification of particularly valuable inert gases, such as krypton and xenon, due to the need to fill them with the space between the retort and the heater to create a heat transfer medium.

 The objective of the present invention is to increase the depth of purification of the inert gas and reduce energy consumption.

 The problem is solved in that in the known device for purification of inert gas, equipped with process pipes and a heat exchanger, including a thermally insulated body with a removable cover and a bottom, in which a heater and an inner cylindrical retort with a perforated bottom filled with a solid absorber, according to the invention, an inner retort placed coaxially in the outer retort with the formation of an annular gap for the passage of the cleaned gas and in the lower half is filled with alternating layers s solid absorber with a nozzle and without it; the heater is installed on the outer surface of the outer retort and placed in a casing; the heat exchanger is mounted in the upper half of the inner retort and is a screen heat insulator with plates polished in the direction of gas movement; technological branch pipes are located on the surface of the outer retort protruding above the housing cover.

 The nozzle is a left and right spiral made of a metal tape, into the slit gaps of which the absorber is filled.

 It should be noted that a device for gas purification is known, including a cooled case with a spiral nozzle made of metal amalgamated tape, the outer turn of which is connected to the inner surface of the housing, and the inner one with the outer surface of the outlet pipe (see ed. St. USSR N 959808, cl. B 01 D 53/04, declared 03.11.80, publ. 23.09.82 g).

 The inventive device contains a similar feature of a spiral nozzle. However, the known device is designed to solve a different problem than the claimed invention, cryogenic gas purification, and the spiral nozzle serves to develop a heat exchange surface in the gas stream.

 Therefore, the analysis of known technical solutions allows us to conclude that the claimed invention is not known from the level of the studied technology and meets the criterion of "novelty."

 The essence of the claimed invention for a specialist does not follow explicitly from the prior art, which indicates its compliance with the criterion of "inventive step".

 The possibility of manufacturing the proposed device for purification of inert gas at engineering enterprises (instrumentation) from commercially available structural elements and materials allows us to conclude that it meets the criterion of "industrial applicability".

 The drawing schematically depicts the inventive device for purification of inert gas.

Designations in the drawing:
1 technological branch pipes;
2 heat exchanger;
3 building;
4 heat insulation of the case;
5 removable housing cover;
6 removable bottom of the case;
7 heater;
8 inner retort;
9 perforated bottom of the inner retort;
10 solid absorber;
11 outer retort;
12 nozzle;
13 heater cover;
14 plates of the heat exchanger.

 The proposed device for purification of inert gas includes a steel cylindrical body 3 (height 1500 mm, diameter 500 mm), thermal insulation 4 of which is made of kaolin wool. The cover 5 and the bottom 6 are mounted on the housing 3 by means of flange connectors (not shown in the drawing).

 The casing 13 of the heater 7 is metal, fixed with rods on the housing cover and can be filled with inert gas (argon) in order to prevent oxidation of the cable.

 The inner cylindrical retort 8 is placed coaxially in the outer retort 11 made of heat-resistant steel. Both retorts are bolted (not shown).

 The heater 7 is a spiral winding of a heat-resistant heating cable mounted on the outer surface of the outer retort 11.

A solid absorber 10, spongy titanium (or another getter) is covered with alternating layers in the lower half of the inner retort 8. The layers are:
solid absorber 10;
a layer with a nozzle 12 a right or left spiral made of steel metal tape, 100 mm high, into the slit gaps of which the absorber 10 is filled.

 The heat exchanger 2 is mounted in the upper half of the retort 8 and is a screen heat insulator made of steel with 30 plates polished in the direction of the gas movement 14. The plates 14 are separated from each other by rods (not shown in the drawing) and are installed so that one plate touches the wall of the housing and has a hole in the center, the other is installed with a gap with respect to the housing.

 Technological nozzles 1 are located on the outer surface of the outer retort 11, protruding above the cover 5 of the housing 3.

 The inventive device for purification of inert gas works as follows.

The device is preliminarily prepared for work by sequentially evacuating the internal retort 8 and activating the absorber 10. Then, voltage is supplied to the heater 7 by heating the absorber to a temperature of nitrogen chemisorption of 850 ^o C (for other impurities, heating is carried out to their chemisorption temperature). The heating is controlled by thermocouples that are installed at 3 control points: in the upper and lower parts of the absorber 10 and in the upper part of the heater 7. Thermocouples in the absorber are installed in 8 cartridges that are hermetically welded to the retort body.

After reaching the set chemisorption temperature, the gas to be cleaned (xenon containing nitrogen, water, hydrogen, methane and other hydrocarbons
1.5 2% vol.) Through the pipeline through the technological pipe 1 for introducing gas enters the annular gap between the inner 8 and outer 11 retorts. Passing through the gap, the gas to be cleaned is heated:
in the area of the screen heat insulator through the wall of the retort 8 with heat of purified gas;
in the area of the heater 7 through the wall of the outer retort 11.

 The gas heated to operating temperature through the perforated bottom 9 enters the alternating layers of the absorber 10 and nozzles 12 with the absorber.

The proposed design provides high efficiency of the chemisorption process by eliminating channel formation in the absorber volume and uniform distribution of gas in the getter. When gas passes through the absorber, it is purified to 0.0001 0.00005% vol. nitrogen depending on customer requirements. After the purified gas leaves the absorber zone, it enters the heat exchanger, where, passing between the plates 14 polished in the course of its movement, it is cooled to 100 ^° C, due to heat transfer through the wall of the retort 8 of the newly received portion of gas. The cooled gas through the technological pipe 1 of the gas outlet leaves the device.

The use of the claimed invention for purification of inert gas in comparison with the known device taken as a prototype (see ed. St. USSR N 1049089, class B 01 D 53/04, decl. 11.06.82, publ. 23.10.83 g), provides the following technical and socially beneficial benefits:
increasing the inert gas purification depth to 0.5 • 10 ^-4 1 • 10 ^-4 % vol. instead of (4 6) • 10 ^-4 % vol.

reduction in energy costs;
the ability to clean particularly valuable inert gases such as krypton and xenon;
elimination of product gas losses;
simplicity of repair, operation and maintenance;
downsizing;
ensuring environmental safety of the device.

Claims (2)

 1. An inert gas purification device equipped with process pipes and a heat exchanger, including a thermally insulated body with a removable cover and a bottom, in which a heater and an inner cylindrical retort with a perforated bottom filled with a solid absorber are installed, characterized in that the inner retort is placed coaxially in the outer retort with the formation of an annular gap for the passage of the gas to be cleaned and in the lower half is filled with alternating layers of a solid absorber with a nozzle and without it, on the heater is installed on the outer surface of the outer retort and placed in a casing, the heat exchanger is mounted in the upper half of the inner retort and is a screen heat insulator with plates polished in the direction of gas movement, technological pipes are located on the surface of the outer retort protruding above the housing cover.  2. The device according to claim 1, characterized in that the nozzle is a left or right spiral of a metal tape, in the gap gaps of which the absorber is filled.