Method of cleaning exhaust gases of sulphur production

 

(57) Abstract:

The invention relates to a method for cleaning exhaust gases of the production of sulfur containing H₂S, SO₂COS, CS₂. The essence of the method lies in the fact that the cleaned gas is passed at 250-350°C over a catalyst consisting of either titanium dioxide or titanium dioxide, containing 1-20 wt.% sulphate of calcium, or strontium, or barium, followed by cooling of the gas and its processing method Claus at 100-160°C and a molar ratio of H₂S : SO₂= 2:1 to produce elementary sulfur. 2 C.p. f-crystals, 1 tab., 1 Il.

The invention relates to the purification of sulfur-containing industrial gases.

More specifically, the invention relates to the purification of the residual gases in the production of sulfur containing from 0.2 to 4% vol. H₂S, SO₂and at least one of the compounds COS and CS₂.

A known method of cleaning gases production of sulfur containing COS, CS₂and SO₂including gidrogenizirovanii and catalytic hydrolysis of sulfur-containing gases, cooling the residual gas and the subsequent catalytic processing it according to the method Claus at a temperature of 100-160^aboutC and a molar ratio of N₂S: SO₂=2:1 with polyclonality, associated with the implementation of gidrogenizirovanii sulfur-containing gases and intermediate stages of cooling gas flows and oxidation of hydrogen sulfide.

The purpose of the invention is to facilitate the method.

This goal is achieved by the proposed method to obtain purification of the residual gases in the production of sulfur containing water vapor and sulfur compounds from 0.2 to about 4. % consisting of H₂S and SO₂and at least one of the compounds COS and CS₂including hydrolysis OS and CS₂at a temperature of from 250 to 350^aboutWith the hydrolysis catalyst, cooling the residual hydrolyzed gas and the subsequent processing is cooled in the presence of a catalyst Claus at a temperature of from 100 to 160^aboutC and a molar ratio of N₂S:SO₂equal to 2:1 with obtaining sulfur, and characterized in that the hydrolysis of COS and CS₂carry on the catalyst based on titanium dioxide, or consisting only of titanium dioxide, or of titanium dioxide containing from 1 to 20 wt.% sulphate of calcium, strontium or barium.

The contact time of the residual gas with the catalyst of hydrolysis, i.e. the duration of the hydrolysis is mainly from 0.5 to 10 C. These values are given for standard conditions poverhnosti, measured by the method of WET constituting from 5 to 300 m²/g, and the total porous volume defined by the method of mercury penetration, of 0.05 to 0.6 cm³/,

For heating the hydrolyzed residual gas to the temperature required for purification method Claus, mainly, you can use indirect heat exchanger with an agent having an appropriate temperature.

Keeping the molar ratio of N₂S: SO₂equal to 2:1 in gidrolizovannogo residual gas supplied to the treatment, may be known for this regulatory methods, for example, by varying the ratio of expenses acid gas and gas containing free oxygen introduced to the sulfur plant with this change, primarily, by maintaining a constant flow rate of sour gas fed to the sulfur plant, and by changing the flow rate of gas containing free oxygen.

The method is described below with reference to the diagram, as shown on the accompanying drawing, which schematically represents a consistently United sulfur plant Claus 1, hydrolysis reactor 2, the catalytic purification unit 3, a furnace for sigonius, which can be selected from such compounds as bauxite, aluminum oxide, silicon dioxide, natural or synthetic zeolites, which are usually used for the formation of sulfur between H₂S and SO₂.

Sulfur plant 1 includes, on the one hand, the combustion chamber 6, which contains the burner 7, provided with a pipe 8 for supplying an acidic gas and a pipe 9 for supplying air, the latter pipe provided with a valve 10 with an adjustable valve, and which has an exit 6A for gases, and, on the other hand, the first catalytic Converter 11 and the second catalytic Converter 12, each of which has one input, respectively, 11a and 12A, and one output, respectively 11b and 12b separated by a fixed catalyst bed reactor. The combustion chamber 6 and the catalytic converters 11 and 12 are set sequentially so that the output 6A of the combustion chamber was connected to the input 11a of the first Converter 11 through the first sulfur condenser 13, then the first heater 14, and the output 11b of the specified first Converter was connected to the input 12A of the second Converter 12 through the second sulfur condenser 15, then the second heater 16, and the output 12b UDC 17b for gases, which is output from the sulphur plant.

The catalytic purification unit 3 contains two catalytic reactor 18 and 19, mounted in parallel and having, each, on the one hand, the inlet pipe for the purified gas, respectively 20 and 21, and the specified inlet pipe fitted with a valve, respectively 20A and 21A, and the injection pipe, respectively 22 and 23 of the regeneration gas and cooling, with the specified injection pipe provided with a valve, respectively, 22A and 23a, and, on the other hand, the output pipeline purified gas, respectively 24 and 25, and the output pipe fitted with a valve, respectively 24A and 25A, and an outlet pipe, respectively 26 and 27 eluent regeneration and cooling, with the specified outlet pipe provided with a valve, respectively, 26a and 27A. Input pipelines, respectively 20 and 21, catalytic reactors 18 and 19 are connected through appropriate valves 20A and 21A, to the pipe 28, which forms the entrance of the catalytic purification unit 3. Similarly, outlet pipes, respectively, 24 and 25, these catalytic reactors 18 and 19 are connected through appropriate valves 24A and 25A, to the pipe 29, obraz and injection pipelines separated from the output holes and outlet pipes fixed bed catalyst Claus. Insectine pipelines 22 and 23 of the reactors 18 and 19 set in parallel through the respective valves 22A and 23a at one end 30A of the conduit 30 is circulating regeneration gas and cooling and discharge pipes 26 and 27 of these reactors also installed in parallel at the other end 30b of these reactors also installed in parallel at the other end 30b of the specified pipe 30. This conduit 30 is set from the end 30b by the end of 30A, sulphur condenser 31, the fan 32, valve 33, a heater 34 and the outlet 35, provided with a valve 35A, and the ends of the specified challenge facing the pipe 30, one between the fan 32 and the valve 33 and the other below the heaters 34. The fan 32 is mounted on the pipe 30 so that the suction hole of the fan is connected with a sulfur condenser 31. The pipe 29, which forms the output of the cleaning unit 3, is connected through line 45, to the furnace combustion 4, which is connected, through line 46 to the chimney 5.

Hydrolysis reactor 2 has one input 2A out 2b separated from one another a fixed layer hydrolytic catalyst. Exit 17b sulfur plant 1 is connected by a pipe 36, through the heater 37 type indirect theres cooling system 39 type indirect heat exchanger, to the pipe 28, which forms the entrance of the unit clean.

The analyzer 40, for example, type interferential spectrometer installed with the bend on the pipe 38 below the cooling system 39, and the specified analyzer carries out the determination of the molar content of N₂S and SO₂in the gas circulating in the pipe 38, and sends a signal 41 representing the instantaneous value of the molar ratio of N₂S:SO₂in the specified gas. The signal 41 is served by a computer 42, which generates a signal 43 representing the adjustment of the air flow to bring the instantaneous molar ratio of H₂S:SO₂to the target value, and the specified signal 43 serves on the flow regulator 44, which regulates the opening of the valve 10, which provides regulation of the air flow introduced to the sulfur plant through a pipeline 9.

In this setting, the implementation of the method can schematically be represented as follows.

It is assumed that the reactor 18 is in phase reaction, and the reactor 19 is in a regeneration phase, the valves 20A, 24A, 23a, 27A and 33 are open at the same time as the valves 21A, 22A, 25A, 26a and 35A are closed.

2S and SO₂and elemental sulfur. This effluent, after separation of the contained sulfur in the first sulfur condenser 13, is heated in the first heater 14 and is directed to the first Converter 11. Upon contact with the Claus catalyst contained in the Converter, connect the H₂S and SO₂available in gas afluente, react with sulphur. The reaction mixture is received from the Converter 11, after the separation of the contained sulfur in the second capacitor 15, followed by heating in the second heater 16, is sent to the second Converter 12, in which is formed a new amount of sulfur by catalytic reaction between H₂S and SO₂. The reaction mixture coming from the Converter 12, exempt from the contained sulfur in the third capacitor 17.

Via exit 17b for gases specified capacitor, which forms the output of the sulphur plant, remove residual gas containing water vapor and less than about 4. % in General, the sulfur compounds containing H₂S, SO₂COS and/or CS₂and a very small amount of steam and/or porous sulfur.

2available in the specified residual gas, hydrolyzed to N₂S in contact with the catalyst contained in the specified reactor 2. Via exit 2b hydrolysis reactor, remove the hydrolyzed residual gas containing H₂S and SO₂and, essentially, without COS and CS₂. Hydrolyzed residual gas, after cooling to an adequate temperature in the cooling system 39, is injected through the pipe 38 into the pipe 28 of the catalytic purification unit, which forms the entrance of the specified Assembly.

Hydrolyzed residual gas passing through the pipe 28, is introduced into the catalytic reactor 18, in which connection the H₂S and SO₂contained in the specified residual gas, interact with each other for the formation of sulfur. The temperature of the gas stream is brought into contact with a Claus catalyst contained in the reactor 18 is such that the formed sulfur is deposited on the catalyst. Through line 24 of the reactor 18 goes purified residual gas with an extremely small content of sulfur compounds, which is directed through the valve 24A, the pipe 29 and pipe 45, into the furnace of burning is for purge supplied through pipe 30 regeneration under the action of the fan 32 is provided in the heater 34 to the temperature required for regeneration of the Claus catalyst on which is deposited sulfur. The flow of heated gas is introduced into the reactor 19 by pipe 23 through the valve 23a and blows saturated sulfur catalyst Claus contained in the specified reactor. The purge gas flow entrained vapors of sulfur released from the reactor 19 through line 27 and passes through the valves 27A and the pipe 30, to the sulfur condenser 31 in which the majority of the sulphur is separated by condensation. At the outlet of the condenser 31, the purge gas flow is caught by the fan 32 for discharge to the reactor inlet 19 through the heater 34. After quite a long purge of the catalyst contained in the reactor 19, the hot purge gas coming from the heater 34, for complete removal of sulfur deposited on the catalyst, and thus, for the regeneration of the specified catalyst, open the valve 35A and close the valve 33 to a short circuit of the heater 34 and to reduce the temperature of the gas purge to values below about 160^aboutWith and continue blowing for a time sufficient to cool regenery the soup temperature, allowing contact of the catalyst with a gas stream coming from the hydrolysis reactor 2, change the functions performed by the reactors 18 and 19, i.e. transform the reactor 19 in phase Claus reaction, and the reactor 18 is in a phase of regeneration/cooling. To do this, close the valves 20A, 23a, 24A, 27A and 35A and open the valves 21A, 22A, 25A, 26a and 33, and then, at the stage of cooling, close the valve 33 and opening valve 35A.

The analyzer 40 of the regulatory system established by the specified analyzer, computing machine 42 and the control valve 44, continuously determines the molar content of N₂S and SO₂hydrolyzed residual gas which passes into the pipe 38 below the cooling system 39 posted after hydrolysis reactor 2, and sends a signal 41 representing the instantaneous value of the molar ratio of N₂S:SO₂in the specified residual gas. On the basis of the signal 41, the computer 42 43 produces a signal representing the adjustment of the flow rate of air supplied to the sulfur plant to bring instantaneous molar ratio of N₂S:SO₂in the residual gas that is included in the unit 3 catalytic purification, the set value is 2: 1. In response to the signal 43, which is the wire 9 for supplying air to the sulfur plant 1 and thus, changes the air flow introduced into the specified sulfur plant, the amount that can withstand the specified value of the molar ratio of N₂S:SO₂in the residual gas that is valid for unit 3 catalytic purification.

Below are examples of the implementation of this method.

P R I m e R s 1-6. Using a setting similar to the installation shown schematically in the attached drawing, and working as described above, receives sulfur from sour gas containing volume. 70.1% OF N₂S, 5%H₂OH, 24.4% OF CO₂, 0.3% OF CH₄and 0.2% linear alkanes WITH₆-C₇.

The catalyst was placed in a hydrolysis reactor 2, is extrudates with a diameter of 4 mm, based on titanium dioxide, containing 10 wt.% SO₄(example 1), titanium oxide (example 2), or titanium dioxide, containing, respectively, 20 wt. % SO₄(example 3), 1 wt.% SO₄(example 4), 20 wt.% CaSO₄(example 5) and 15 wt.% SrSO₄(example 6).

The Claus catalyst present in the catalytic converters 11 and 12 sulfur plant 1, as well as in the reactors 18 and 19 unit 3 catalytic cleaning, made of beads, with a diameter of 2-5 mm of aluminum oxide having a specific p the ate 11 and 12 operate at temperatures equal, respectively, about 1100, 300 and 250^aboutC.

Via exit 17b sulfur plant, remove residual gas having a temperature of 142^aboutC and absolute pressure of 1.15 bar. This residual gas is in percent by volume, the following composition, excluding steam and bubble sulfur: N₂54,84 H₂O 30,54 H₂2.26 AND CO 0,97 CO₂10,08 H₂S 0,74 SO₂0,45 COS 0,08 CS₂0.04

The output of the sulfur recovery sulfur plant 1 was 95,1%.

The residual gas, remote from the sulphur plant is brought to a temperature of 300^aboutWith the heater 37, and then is introduced into the hydrolysis reactor 2, operating at this temperature. The contact time of the residual gas with the catalyst contained in the hydrolysis reactor is 3 seconds in normal conditions of pressure and temperature.

Hydrolyzed residual gas discharged from the reactor 2, contains only traces of COS and CS₂while the degree of hydrolysis of these compounds exceeds 99%.

Hydrolyzed residual gas is cooled to 132^aboutWith by passing through the cooling system 39, and then served at this temperature and a molar ratio of N₂S:SO₂, endured a value of 2:1 by the control system, the system catalog 29, connected to the output of the specified reactor and forming the output unit 3 catalytic cleaning, remove the purified residual gas having a temperature of about 145^aboutWith and containing the total number of sulfur compounds comprising from 1000 p.p.m (in example 5) to 1400 p.p.m in volume (example 2), and specified the purified gas is fed into the furnace combustion 4 through line 45. The ashing is carried out at a temperature of 450^aboutWith by burning fuel gas with a slight excess of air, leading to 1% vol. oxygen in Ozolina the gas supplied to the chimney.

The purge gas used for the regeneration of the saturated sulfur catalyst contained in the reactor in the regeneration phase, followed by cooling, consists of chilled hydrolyzed residual gas collected at the pipe 38 and introduced into the reactor in the regeneration phase after it has been brought to a temperature of 300^aboutC-350^aboutWith the heater 34 of the pipeline regeneration. Saturated sulfur purge gas coming from the reactor in the regeneration phase, is passed then through a sulfur condenser 31 of the pipeline regeneration to cool it down to about 125^aboutWith the mission of the Department, by condensation, for the most part, contained sulfur, the torus is then cooled to a temperature of about 130^aboutWith that flowing in the containing reactor purge gas flowing from the condenser 31 and circulating in the outlet 35, briefly closing the heater 34.

Catalytic reactors 18 and 19 worked alternately for 30 h in the cleanup phase, i.e. during the reaction phase, and within 30 hours, of which 10 hours of cooling, the phase regeneration/cooling.

Sulfur recovery from complex containing sulphur plant, hydrolysis installation, the catalytic purification unit (total yield of sulfur) is, depending on the test from 99.5 to 99.7 per cent, as indicated in the table below.

In the working conditions comparable to the above, the release of sulfur from a complex containing only sulfur plant and the catalytic purification unit, comprised of 99.1%.

1. METHOD of CLEANING EXHAUST GASES of the PRODUCTION of SULPHUR containing water vapor and 0.2 - 4% vol. sulfur compounds consisting of H₂S and SO₂and at least one of the compounds COS and CS₂including hydrolysis last at 250 - 350^oWith the catalyst, cooling the residual gas and the subsequent separation on the catalyst in the Claus process at 100 - 160^oC and a molar ratio of H₂S : SO₂= 2 : 1 to produce elementary sulfur, characterized in that Thu is any of titanium dioxide, containing 1 to 20 wt.% sulphate of calcium, or strontium, or barium.

2. The method according to p. 1, characterized in that the hydrolysis of conduct for 0.5-10 seconds

3. The method according to p. 1, characterized in that the catalyst is used with a specific surface area measured by the method of WET, 5 - 300 m²/g with a total pore volume determined by the method of mercury penetration, of 0.05 - 0.6 cm³/,