CN1163785A

CN1163785A - Catalytic burning technique for hydrogen sulfide in gas

Info

Publication number: CN1163785A
Application number: CN 96104818
Authority: CN
Inventors: 李玉书; 陈桂芬; 李晓东
Original assignee: 李晓东
Priority date: 1996-04-30
Filing date: 1996-04-30
Publication date: 1997-11-05
Anticipated expiration: 2016-04-30
Also published as: CN1056542C

Abstract

A process for catalytic combustion of hydrogen sulfide in gas is suitable to treat the tail gas to recover sulfur by Cross process and the waste gas from geothermal power plant. It features that, the gas containing hydrogen sulfide is introduced into catalytic combustion reactor after mixed with oxygen in which activated carbon as catalyst is provided, where hydrogen sulfide is catalytically oxidized at 200-400 deg.C to change into SO2, which is exhausted into atmosphere along with the gas after reaction. Its advantages are simple apparatus and technology and cheap catalyst.

Description

Catalytic incineration process for hydrogen sulfide in gas

The invention relates to a catalytic incineration process of hydrogen sulfide in gas, which is particularly suitable for treating tail gas of a Claus process for recovering sulfur and waste gas of a geothermal power plant.

Because the toxicity and odor of the hydrogen sulfide are very high, the environmental protection regulation of each country has much lower control on the discharge amount than that of the hydrogen dioxide, so that the hydrogen sulfide is burnt into the hydrogen dioxide and then discharged into the atmosphere in all occasions related to the discharge of the hydrogen sulfide. Among the gases containing hydrogen sulphide which are to be emitted, there are often gases which are not tobe oxidized, such as nitrogen, carbon dioxide, water vapour, etc., which are required to have no significant effect on the catalytic oxidation chosen. In addition, in the presence of oxygen, at certain temperatures, elemental sulfur and sulfur trioxide may be formed, the former depositing on the catalyst and deactivating it and even plugging the catalytic oxidation incineration reactor, and the latter causing new polluting emissions, therefore, the catalytic incineration catalyst and related processes selected should selectively oxidize hydrogen sulfide to carbon dioxide without forming sulfur trioxide and elemental sulfur.

The prior art often uses a pyramidal gas incinerator where a quantity of combustible gas and air are added to a waste gas stream containing hydrogen sulphide, combusted at a temperature above 740 c to convert the hydrogen sulphide to sulphur dioxide, and discharged to the atmosphere. Obviously, this process necessarily consumes a lot of fuel. In order to save energy, it is desirable to oxidize hydrogen sulfide to sulfur dioxide by catalytic incineration using a non-fueled catalytic oxidation process.

US4169136 discloses a method for using 5% -15% of V₂O₅Impregnated in AL₂O₃Or non-alkaline ceramic material as catalyst, and oxidizing hydrogen sulfide in the gas to sulfur dioxide by using oxygen at the temperature of 150-480 ℃. Since the catalyst contains AL₂O₃And active metal oxide, not only is the price expensive, but also the generated sulfur trioxide is easy to inactivate the catalyst, and the total conversion rate of hydrogen sulfide is difficult to reach 100%, so that the catalyst is not popularized and applied up to now.

The invention aims to overcome the defects of the prior art and provide a catalytic incineration process for hydrogen sulfide in gas.

The purpose of the invention is realized as follows: mixing the gas containing hydrogen sulfide with oxygen, introducing the mixture into a catalytic incineration reactor filled with active carbon as a catalyst, converting the hydrogen sulfide into sulfur dioxide through catalytic oxidation at the temperature of 200-400 ℃, and discharging the sulfur dioxide and the reacted gas into the atmosphere. See the attached drawings. The gas containing hydrogen sulfide from the pipeline (1) and the air from the pipeline (2) are mixed and then enter a preheater (3) to be preheated to 250 ℃ at 200 ℃, enter a catalytic incineration reactor (5) through a pipeline (4), and the hydrogen sulfide is converted into sulfur dioxide through catalytic oxidation and is discharged into the atmosphere together with the reacted gas through a pipeline (6) and a chimney (7).

The inlet temperature of the catalytic incineration reactor (5) is controlled at 200 ℃, preferably at 250 ℃, and the outlet temperature is controlled at 400 ℃, preferably below 350 ℃; the molar ratio of oxygen to hydrogen sulfide is 1.8-10, preferably 2-5; airspeed of 1000-10000H^-1. Space velocity is dependent onAt reaction temperature, hydrogen sulfide content and oxygen and hydrogen sulfideIn a molar ratio of (a). If the content of hydrogen sulfide is 0.5 percent, the molar ratio of oxygen to hydrogen sulfide is 5, and the reaction temperature is 350 ℃, the space velocity can reach 10000H^-1。

The reactions that take place in catalytic incineration are mainly:

the equilibrium constant of the reaction is large (K)_204℃＝4.98×10⁵²) SO that water hardly affects SO₂And (4) generating.

As a large amount of heat is released when the hydrogen sulfide is oxidized into sulfur dioxide, the content of the hydrogen sulfide in the feed gas entering the catalytic incineration reactor (5) is not more than 1.5 percent, otherwise, a water cooling coil is required to be arranged in the catalytic incineration reactor (5) to take away the reaction heat, so that the outlet temperature is not more than 350-400 ℃.

In order to save the energy consumption of the preheater (3), the gas to be discharged can be returned through a pipeline (8) to be mixed with the raw material gas, and the temperature of the raw material gas is increased by utilizing the heat of the gas to be discharged.

The catalytic incineration process of hydrogen sulfide in gas has simple equipment and process, cheap catalyst and capability of saving a large amount of combustible gas; non-oxidized gases such as water vapor do not have much influence on the catalytic oxidation selected. Hydrogen sulfide can be selectively oxidized to sulfur dioxide without generating sulfur trioxide and elemental sulfur.

The attached drawing is a flow chart of the catalytic incineration process of hydrogen sulfide in gas

The following examples may further illustrate the process of the present invention.

1 ml of activated carbon is taken as a catalyst, the activated carbon is filled into a glass tube with the inner diameter of 7 mm, two ends of the glass tube are blocked by glass wool, and the glass tube is placed in a heating tube type furnace to simulate a catalytic incineration reactor. The performance of the activated carbon produced by Henan Yu New activated carbon factory is shown in Table 1, and the number of the activated carbon is ZH 2; the activated carbon was ground and a 5-60 mesh fraction was screened as the catalyst in this example. The reaction gas is prepared by nitrogen, carbon dioxide and hydrogen sulfide, and is mixed with heated air to enter a reactor, and the temperature is strictly controlled. The conversion rate of hydrogen sulfide and the generation rate of sulfur dioxide can be calculated by measuring the amounts of hydrogen sulfide in the gas entering the reactor and hydrogen sulfide and sulfur dioxide in the gas leaving the reactor at any time. The results are shown in Table 2.

As can be seen from the data in Table 2, the conversion of hydrogen sulfide can easily reach 100%, and the generation of sulfur dioxide can reach 98%.

TABLE 1

Strength of ％	Capacity of water ％	Benzene adsorption ％	Specific surface area m²/g	Total pore volume cm²/g	Weight of pile g/L
Strength of ％	Capacity of water ％	Benzene adsorption ％	Specific surface area m²/g	Total pore volume cm²/g	Weight of pile g/L	≥90	≥65	＞28	0.85-0.9	800	400-460

TABLE 2

H₂S content V％	H₂Content of O ％	Reaction temperature ℃	Airspeed H^-1	O₂/H₂S Molar ratio of	H₂Conversion of S ％	SO₂Rate of formation ％
H₂S content V％	H₂Content of O ％	Reaction temperature ℃	Airspeed H^-1	O₂/H₂S Molar ratio of	H₂Conversion of S ％	SO₂Rate of formation ％	0.5	4	350	10000	5.0	100	96
4.5	4	280	3000	2.0	100	98	0.5	4	350	10000	5.0	100	96
4.5	4	280	3000	2.0	100	98	4.5	4	350	3000	2.0	100	99
4.5	4	250	3000	4.0	100	90	4.5	4	350	3000	2.0	100	99
4.5	4	250	3000	4.0	100	90	4.5	4	280	6000	2.0	100	98
4.5	30	280	3000	2.0	100	98	4.5	4	280	6000	2.0	100	98

Claims

1. A catalytic combustion process for hydrogen sulfide in gas features that the gas containing hydrogen sulfide and oxygen are mixed and then introduced into catalytic combustion reactor with activated carbon as catalyst, where the hydrogen sulfide is catalytically oxidized at 200-400 deg.C to become sulfur dioxide, which is then exhausted to atmosphere together with the reacted gas.

2. A catalytic incineration process as claimed in claim 1, characterised in that the optimum reaction temperature for the catalytic oxidation is 250-350 ℃.

3. A catalytic incineration process as claimed in claims 1 and 2, characterised in that the amount of cooling water flowing through the coil in the catalytic incineration reactor is regulated to control the reaction temperature thereof.

4. A catalytic incineration process asclaimed in claim 1, characterised in that the molar ratio of oxygen to hydrogen sulphide is between 1.8 and 10.

5. A catalytic incineration process according to claim 1, characterised in that the molar ratio between oxygen and hydrogen sulphide is optimally 2-5.

6. A catalytic incineration process as claimed in claim 1, characterised in that the space velocity is 1000-^-1。

7. A catalytic incineration process according to claim 1, characterised in that the gas to be discharged is returned via line (8) to be mixed with the feed gas.