RU2528792C1 - Method for single-step fractionation separation of inert gases from tail gases and apparatus therefor - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: method of separating inert gases from gases containing at least argon, xenon, krypton, nitrogen and hydrogen includes cooling a starting gas stream, liquefaction and separation via single-step fractionation. Said fractionation is carried out to obtain liquid separation products: argon and a krypton-xenon mixture, and gaseous separation products: nitrogen, mixture of carbon-nitrogen oxides and a nitrogen-hydrogen mixture. Before fractionation, a large part of the gas stream after cooling is condensed, separated and supercooled, and the smaller part is compressed before cooling. The mixture of carbon-nitrogen oxides is subjected to catalytic oxidation of carbon monoxide to obtain carbon dioxide, nitrogen and water at the output, and hydrogen is separated from the nitrogen-hydrogen mixture. An apparatus for separating inert gases is described.

EFFECT: reduced harmful emissions and extraction of valuable components - inert gases - from tail gases.

10 cl, 1 dwg, 1 tbl

Description

The invention relates to the field of gas chemistry, is intended to produce inert gases and can be used to isolate inert gases from the tail gases of gas sulfur production units.

A known method of producing kryptonoxenone concentrate, including compressing the initial gas stream, its purification and cooling to form the main stream and expander stream, purification of the expander stream, separation of the main stream and expander stream with the formation of bottoms liquid stream, circulating oxygen stream and kryptonoxenone concentrate stream, stream cleaning bottoms liquid, purification of the circulating flow, purification of the circulating flow of oxygen and the extraction of liquid separation products - argon and cree ptonoxenone concentrate and gaseous product of separation - nitrogen (RU 2146552, 2000).

The known method boils down to the production of a kryptonoxenone concentrate by purification and separation of air, however, it cannot be implemented using tail gases, for example, the exhaust gases of the Sulfrin plant as an initial gas stream.

A device for producing a kryptonoxenone concentrate is known, comprising a feed air inlet line with an air compression device disposed thereon, a compressed air inlet line connected inlet to an air compression device, and an outlet with an air purification and cooling unit, an expander line with on it there is an adsorption unit for cleaning the expander stream, an input connected to an inlet unit for cleaning and cooling the air, and an outlet for it with a separation unit, a line for the main air stream, an inlet connected to the inlet air purification and cooling unit, and the outlet to the separation unit, including a bottoms liquid flow line with an adsorbed bottoms liquid purification unit located on it, an oxygen circulation stream line with an adsorption oxygen circulation purification unit placed on it, and a kryptonoxenone flow line concentrate, while at least one of the adsorption sites for cleaning the expander stream, and / or the bottoms stream, and / or the oxygen circulation stream is provided with an additional the dash line of the processed output regenerating stream of the corresponding adsorption cleaning unit, and at least one of the additional lines of the processed output regenerating flows of the adsorption cleaning unit of the expander stream, and / or the adsorption unit for cleaning the bottoms stream, and / or the adsorption unit for cleaning the circulating oxygen stream the inlet is connected to the corresponding cleaning unit, and the outlet is connected to the supply line of the inlet air flow with a compression device placed on it air (RU 2146552, 2000).

A disadvantage of the known method and device is the limited conditions for their use, since they are designed to produce inert gases from the air and do not allow the use, for example, of the tail gases of the Sulfrin plant as a source gas.

The technical result of the proposed group of inventions related by a single inventive concept is to reduce harmful emissions and the ability to extract valuable components from inert gases - inert gases.

The technical result is achieved by the fact that, according to the method of separating inert gases from tail gases, the initial gas stream is cooled, liquefied and separated by a single-stage rectification to obtain liquid separation products: argon and a kryptonoxenone mixture and gaseous separation products: nitrogen, a mixture of carbon-nitrogen oxide and a nitrogen-hydrogen mixture .

Before rectification, it is advisable to condense, separate and supercool most of the gas stream after cooling, and compress a smaller part before cooling.

In a specific case, the initial gas flow has the composition: nitrogen up to 96%, hydrogen up to 2%, carbon monoxide up to 1%, xenon from 0.1 ppm, krypton from 1.5 ppm, argon from 1%.

Subsequently, the separation product — a mixture of carbon monoxide — nitrogen can be subjected to catalytic oxidation of carbon monoxide to produce carbon dioxide, nitrogen, and water, and hydrogen can be taken from another separation product — a nitrogen – hydrogen mixture.

The technical result is also achieved by the fact that the device for separating inert gases from the tail gases includes means for separating the initial gas stream, the main heat exchanger, supercooler, the main and krypton columns, the condenser is an evaporator, a liquefier equipped with a commodity argon drain line, a separator connected by its exhaust line liquid fraction with a subcooler, and a kryptonoxenone mixture preparation unit associated with a krypton column and equipped with a discharge of a commercial kryptonoxenone mixture, while The separation of the initial gas flow is connected by one of the outlet lines passed through the main heat exchanger to the condenser-evaporator, the other of the outlet lines through the booster unit to the main column, which is connected to the subcooler, liquefier and, through the condenser-evaporator, to a separator and with a krypton column, the connections of the main column with the subcooler are represented by two pipelines for withdrawing gaseous fractions from the main column to the subcooler and a return pipe, the main liquefied columns are represented by a pipeline for withdrawing part of pure argon gas from the main column to the liquefier and a pipeline for withdrawing steam from the liquefier to the middle part of the main column, communication of the main column through a condenser-evaporator with a separator and with a krypton column is represented by a pipeline for removing liquid argon from the main column to the condenser -evaporator, by a pipeline for supplying a gaseous stream from a condenser-evaporator to the main column, by a pipeline for discharging a liquid fraction from a condenser-evaporator to the separator and the circulation circuit of two pipelines connecting the condenser-evaporator with the upper part of the krypton column, while the gas outlet of the separator and pipelines designed to discharge the exhaust nitrogen and the mixture of nitrogen with carbon monoxide from the supercooler are passed through the main heat exchanger, and the supercooler has a communication line with a fluidizer.

In a preferred embodiment, the booster unit is made in the form of a turboexpander unit according to the “compressor-turbine” scheme, hydraulically interconnected through successively installed additional heat exchanger and filter, the additional heat exchanger made with its own water cooling circuit, and the connection (line) between the additional heat exchanger installed in series and the filter is passed through the main heat exchanger.

In a specific example, the block for preparing the kryptonoxenone mixture is made in the form of an evaporator and a two-phase separator, connected in series through liquid and parallel to gas.

In this particular example, the two inputs of the subcooler are connected by a single pipe to the liquid outlet of the separator, and the main heat exchanger is made of plate-finned.

The proposed method can be used for the separation of heavy inert gases from the tail gases of the Sulfrin plant, after drying, extraction of sulfur and carbon dioxide compounds and having the following composition: nitrogen up to 96%, hydrogen up to 2%, carbon monoxide up to 1%, xenon from 0.1 ppm (0.00001%,), krypton from 1.5 ppm (0.00015%), argon from 1%.

The gas separation process is carried out in several stages:

- cooling in a heat exchanger (main heat exchanger);

- liquefaction and separation of gas into main components through distillation. The technological scheme is based on a low pressure cycle using a turboexpander unit according to the “compressor-turbine” scheme.

The mixture is separated without the use of an external refrigeration cycle with an additional compressor (booster unit), the mixture is fed to the separation under a pressure of 7 MPa.

The rectification unit consists of two columns: the main and krypton. The main separation apparatus is built according to a single-stage rectification scheme. Reflux irrigation of the main distillation column is carried out by the initial mixture, which condenses in the condenser-evaporator of this column.

The separation products are:

a) liquid argon;

b) high purity liquid kryptonoxenone mixture (recovery not lower than 99%);

c) gaseous nitrogen-hydrogen mixture:

g) a mixture of carbon monoxide - nitrogen gas;

d) gaseous nitrogen.

The drawing shows a schematic process diagram of a device designed to implement the proposed method.

The device for separating inert gases includes means 1 for separating the initial gas stream, a main heat exchanger 2, a subcooler 3, a main and krypton columns 4, 5 with trays 6, a condenser-evaporator 7, a fluidizer 8, equipped with a commodity argon drain line 9, a separator 10, connected its line 11 of the removal of the liquid fraction with subcooler 3, and the block 12 for the preparation of the kryptonoxenone mixture associated with the krypton column 5 and equipped with a drain 13 of the commodity kryptonoxenone mixture. Means 1 for separating the initial gas stream is connected by one of the outlet lines 14, passed through the main heat exchanger 2, to the condenser-evaporator 7, the other of the outlet lines 15, through the booster unit 16, with the main column 4. The connections of the main column 4 with the subcooler 3 are two pipelines 17, 18, the withdrawal of gaseous fractions from the main column 4 to the subcooler 3 and the return pipe 19. The connections of the main column 4 with the liquefier 8 are represented by the pipe 20 of the removal of a portion of pure argon gas from the main the strings 4 into the liquefier 8 and the pipeline 21 for withdrawing steam from the liquefier 8 to the middle part of the main column 4. The connections of the main column 4 through the condenser-evaporator 7 with the separator 10 and with the krypton column 5 are represented by the pipe 22 for the output of liquid argon from the main column 4 to the condenser- the evaporator 7, a pipeline 23 for supplying a gaseous stream from the condenser-evaporator 7 to the main column 4, a pipe 24 for draining the liquid fraction from the condenser-evaporator 7 to the separator 10, and a circulation circuit from two pipelines 25, 26 connecting the cond the evaporator-evaporator 7 with the upper part of the krypton column 5. The gas outlet 27 of the separator 10 and the pipelines 28a, 28b, designed to discharge the waste nitrogen and nitrogen mixture with carbon monoxide, respectively, from the supercooler 3, are passed through the main heat exchanger 2. The supercooler 3 has a line 29 communication with liquefier 8. Booster unit 16 is made in the form of a turboexpander unit according to the scheme “compressor 30-turbine 31” hydraulically interconnected through sequentially installed additional heat exchanger 32 and filter 33. Additional eploobmennik 32 is configured with its own cooling water circuit 34. The connection (line) between sequentially installed additional heat exchanger 32 and the filter 33 is passed through the main heat exchanger 2.

Block 12 for the preparation of the kryptonoxenone mixture is made in the form of an evaporator 35 and a two-phase separator 36, connected in series in liquid and parallel to gas. The evaporator 35 is equipped with an active fluid circuit with inlet and outlet pipes 37, 38.

From the source of information (Russian Gas Encyclopedia. / Ed. By R.I. Vyakhirev. M., Big Russian Encyclopedia, 2004, p. 433) it is known that various modifications of shell-and-tube heat exchangers are used as evaporators. A characteristic feature of evaporators is the presence of a zone of separation of liquid and vapor, formed, for example, by increasing the free volume of the annulus.

The separator 10 is closed by its line 11 of the removal of the liquid fraction to the subcooler 3 in such a way that the two inputs of the subcooler 3 are connected by a single pipe (line 11) with the liquid output of the separator 10.

The method is as follows. The source gas stream, for example, with a pressure of 7 atm and a temperature of 450 ° C, enters the installation in the form of an initial gas stream and is divided into two streams (two parts) by means of 1: one (large) part enters the main plate-fin heat exchanger for cooling (T-01) 2, the other (smaller) part in the form of an expander stream enters the booster unit (TDK-01) 16. The stream after the booster (booster) compressor 30 is cooled by water in an additional heat exchanger 32 and enters the main heat exchanger (T-01 ) 2, where it is cooled by reverse flows nitrogen-hydrogen mixture, waste (waste) nitrogen and fraction CO-N ₂ (a mixture of nitrogen with hydrogen oxide) and is removed from the middle part of the heat exchanger 2. Next, the squeezed gas is sent through a filter (F-01) 33 to the turbine of the turbine expander unit (TDK-01) 16, where, expanding, it cools and enters the middle of the main (packed) column (K-01) 4.

After cooling, the main gas stream (1-1) is directed to the condenser-evaporator (KI-01) 7, where it partially condenses (1-12). Next, the vapor-liquid mixture enters the separator 10, where it is divided into steam (1-3) and liquid (1-4). Steam stream 27 (1-3) is withdrawn by reverse flow through the main heat exchanger (T-01) 2 from the unit in the form of a hydrogen-enriched nitrogen-hydrogen mixture. The fluid flow 11 (1-4) is divided into two flows - (1-5) and (1-4-1). The flow rate (1-5) is significantly less than the flow rate (1-4-1). Streams (1-5) and (1-4-1) pass through a subcooler (PE-01) 3.

The stream (1-5) is supercooled by heating gaseous flows of nitrogen (1-14) and the fraction CO-N ₂ (1-13), leaving the main column (K-01) 4 with a pressure of 1.3 bar, and throttled (1- 6) to the top of this column (K-01) 4. Flowing down the column 4, the liquid is enriched with argon due to heat and mass transfer with vapors rising along the column 4 from the condenser-evaporator 7. Liquid argon is taken from the cube of the main column 4 (1 -7), which is sent to the condenser-evaporator (KI-01) 7, where it partially evaporates due to the exchange of heat with condensing gas.

The gaseous stream (1-8) from the condenser-evaporator (KI-01) 7 is directed back to the main column (K-01) 4. Argon vapor, rising along column 4, passes five plates and is washed from krypton and xenon. Part of the pure gaseous argon (1-9) is removed from the main column (K-01) 4 and fed to a liquefier (ОЖ-01) 8. There, a supercooled stream (1-10) is supplied from the subcooler (PE-01) 3, at the evaporation of which part of the stream (1-9) condenses. Commodity liquid argon passes through commodity argon discharge line 9 from a liquefier (ОЖ-01) 8 to the cryogenic capacity of product argon (not shown). The steam stream (1-11) from the fluidizer (ОЖ-01) 8 is diverted to the middle part of the main column (К-01) 4.

The fluid flow (1-2) from the condenser-evaporator (KI-01) 7 is fed into the upper part of the krypton column (K-02) 5, connected in the lower part to the block 12 for preparing the kryptonoxenone mixture. From the evaporator (I-01) 35, the liquid phase enters a two-phase separator 36, from which the pure kryptonoxenone mixture is taken in liquid form through the discharge 13 of the commercial kryptonoxenone mixture. The gas phase from the block 12 for the preparation of the kryptonoxenone mixture is returned to the cube of the main column (K-01) 4.

Example

A gas of the following composition is supplied to the installation for separating heavy inert gases from the tail gases of the Sulfrin installation: (in molar fractions) 0.017 H ₂ , 0.961 N ₂ , 0.012 Ar, 0.010 СО, 0.01 ppm Хе, 1.5 ppm Kr. The flow pressure is 7 bar, the temperature is 228 K, the volumetric flow rate of the gas mixture is 1.13 * 105 nm / h.

The composition and characteristics of gas separation products are presented in the table.

Table The composition and characteristics of gas separation products Stream name Nitrogen Frac. With Kr + Xe liquid ARG fluid Frac. H ₂ one 2 3 four 5 6 Temperature, K 227.5 225 125.1 89.75 225 Pressure bar 1.25 1.25 1.4 1.3 6.85 Volumetric flow rate, nm ³ / h (for gas) 1.09E + 05 150 0.175 0.175 0.175 Composition, mole. share Hydrogen 0.0114 0.0012 0 0 0.3508 Nitrogen 0.9757 0.2377 0 0 0.6411 Argon 0.0048 0.0188 0 one 0.0038 Krypton 0 0 0.9363 0 0 Xenon 0 0 0.0637 0 0 Carbon monoxide 0.0081 0.7424 0 0 0.0043

Claims (10)

1. The method of separation of inert gases from gases containing at least argon, xenon, krypton, nitrogen and hydrogen, including cooling the initial gas stream, liquefaction and separation through a single-stage distillation to obtain liquid separation products: argon and kryptonoxenone mixture, and gaseous separation products: nitrogen, a mixture of carbon monoxide-nitrogen and a nitrogen-hydrogen mixture, characterized in that before rectification, most of the gas stream after cooling is condensed, separated and supercooled, and a smaller the part is compressed before cooling, while the carbon-nitrogen oxide mixture is subjected to catalytic oxidation of carbon monoxide to produce carbon dioxide, nitrogen and water, and hydrogen is released from the nitrogen-hydrogen mixture. 2. The method according to claim 1, in which an initial gas stream is used, having the composition: nitrogen up to 96%, hydrogen up to 2%, carbon monoxide up to 1%, xenon from 0.1 ppm, krypton from 1.5 ppm, argon from 1%. 3. A device for the extraction of inert gases, including a means for separating the initial gas stream, a main heat exchanger, a subcooler, a main and krypton columns, a condenser-evaporator, a liquefier equipped with a discharge line of commodity argon, a separator closed with its own liquid line to the subcooler, and a block preparing a kryptonoxenone mixture associated with a krypton column and equipped with a discharge of a commodity kryptonoxenone mixture, while the means for separating the initial gas stream is connected to one of the outlet highways passed through the main heat exchanger, with a condenser-evaporator, another of the output lines through a booster unit with a main column, which is connected to a subcooler, a fluidizer and through a condenser-evaporator with a separator and a krypton column, and the main column is connected to a supercooler with two pipelines for the withdrawal of gaseous fractions from the main column to the subcooler and a return pipe, the connections of the main column with a liquefier are represented by a pipeline for removing part of the clean argon gas from the main column to the liquefier and the steam withdrawal line from the liquefier to the middle part of the main column, the main column connections through a condenser-evaporator with a separator and with a krypton column are represented by the liquid argon withdrawal line from the main column to the condenser-evaporator, the gaseous flow from the condenser-evaporator to the main column, by the pipeline for removing the liquid fraction from the condenser-evaporator to the separator and the circulation circuit from two pipelines, I connect their condenser evaporator to the upper part of the krypton column, the gas outlet of the separator and pipes intended for the removal of waste nitrogen from subcooler and nitrogen mixture with carbon monoxide are passed through main heat exchanger, subcooler and a connection line liquefier. 4. The device according to claim 3, in which the booster unit is made in the form of a turboexpander unit. 5. The device according to claim 4, in which the turboexpander unit is made according to the "compressor-turbine" scheme, hydraulically interconnected through sequentially installed additional heat exchanger and filter. 6. The device according to claim 5, in which the additional heat exchanger is made with its own water cooling circuit. 7. The device according to one of paragraphs.4-6, in which the connection between sequentially installed additional heat exchanger and the filter is passed through the main heat exchanger. 8. The device according to claim 3, in which the block for preparing the kryptonoxenone mixture is made in the form of an evaporator and a two-phase separator, connected in series through liquid and parallel to gas. 9. The device according to claim 3, in which the two inputs of the subcooler are connected by a single pipe to the liquid output of the separator. 10. The device according to claim 3, in which the main heat exchanger is made plate-ribbed.