DE2717633A1 - PRODUCTION OF SULFUR AND SULFURIC ACID FROM HYDROGEN SULFUR - Google Patents

Description

Society for high temperature reactor technology mbH 5060 Bergisch Gladbach 1

Production of sulfur and sulfuric acid from hydrogen sulfide

The present invention relates to a method and a plant for the recovery of sulfur and sulfuric acid from hydrogen sulphide by combustion and is particularly suitable for large systems in which gases with a high proportion of hydrogen sulphide partly to elemental sulfur and partly to sulfuric acid should be implemented. The proportions of sulfur and sulfuric acid production can be changed. aside from that the sulfur dioxide content in the exhaust gas can be reduced considerably compared to the known systems.

According to the so-called Claus process, hydrogen sulfide is processed into elemental sulfur through partial oxidation and subsequent reaction between H_S and S0_ on bauxite contacts. Since the conversion at the Claus contact furnace is a maximum of only 98% and cannot be increased with technically justifiable means, an exhaust gas with a "corresponding amount of H ₂ S, COS, CS ₃ , SO, and a proportion of sulfur vapor corresponding to the partial pressure" is produced Because of the toxicity of the H ₂ S and the organic sulfur compounds, the exhaust gas from the Claus contact furnaces is burned in an afterburning furnace and then released into the atmosphere

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given. This produces an exhaust gas with approx. 5,000 - 60,000 ppm SO ». In order to keep the air clean, attempts have now been made to reduce these SO “emissions. So was z. B. arranged after the last Claus contact furnace, a further stage with the implementation in the liquid phase. This made it possible _{to reduce the S0 2} emissions to 1000 ppm. In the case of larger systems, however, this is still a nuisance to the environment.

The object of the present invention is a method and a plant for the production of sulfur and sulfuric acid from hydrogen sulfide with low SO_ emissions into the atmosphere. ~

To solve this problem, a method according to claim 1 is proposed. This proposed combustion with a small proportion of air, reaction 1 essentially takes place:

2 H ₂ S + O ₂ = 2 S + 2 H ₂ O

and only to a small extent after reaction 2: H ₂ S + 3/2 O ₂ = SO ₂ + H ₂ O

Therefore, a large part of the hydrogen sulfide is desirably converted into elemental sulfur (up to 70% of the total amount) and only a small part is converted into sulfur dioxide. The heat of combustion will to a large extent released in a steam generator, the steam at an economical temperature and Releases pressure level. In the following sulfur condenser, the gas is further cooled and the largest share of the elemental sulfur formed

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condensed at very low temperatures and withdrawn in liquid form. The heat dissipated here can at best be used to generate steam at a low temperature or pressure level. The gas leaving the sulfur condenser contains H ₂ S, COS, CS ₃ , SO ₃ , as well as small amounts of vaporous elemental sulfur, corresponding to the partial pressure. These gases are completely burned to SO »in a second furnace with a large proportion of air. This S0_ is cooled in a further steam generator and processed into sulfuric acid in a known manner (for example in a double absorption system or a wet catalysis system).

The bypass line proposed in the second claim has essentially two advantages. If the gases entering the first furnace _{contain only small amounts of H 2} S or, for example in the event of malfunctions, only occur in small quantities, the combustion temperature in the second furnace would no longer be sufficient for complete combustion without additional heating. So if a partial flow of the H_S gas is passed through this bypass line directly into the second furnace, a sufficient combustion temperature and, accordingly, complete combustion to S0_ is always guaranteed there. In addition, by increasing the volume flow in this bypass line, the proportion of sulfuric acid production can be increased compared to the proportion of elemental sulfur production.

The figure shows a possible embodiment of the invention in a highly schematic form. The one containing hydrogen sulfide Gas is burned in the combustion chamber 1 with a small amount of air. In the steam

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generator 2, a large part of the heat of combustion is used to generate steam under economical conditions and a small proportion of elemental sulfur is withdrawn in liquid form in the colder part. In the sulfur condenser 3, which has to work in a narrowly limited temperature range of approx. 120 to 140 ° C with regard to the special flow properties of elemental sulfur, a very large proportion of the sulfur is deposited in liquid form and its heat of condensation, albeit at a low level Pressure or temperature level dissipated. _{The gases emerging from the sulfur condenser are completely burned to SO 2} in the combustion chamber 4 with a large proportion of air, then cooled in a steam generator 5 and processed into sulfuric acid in a sulfuric acid plant 6, which is not described in detail. The exhaust gases emitted here are completely free of hydrogen sulfide and only contain very small amounts of sulfur dioxide. If the combustion temperature reached in furnace 4 is no longer sufficient for complete combustion or if the sulfuric acid production should be increased at the expense of sulfur production, the bypass line 7 is opened, and more hydrogen sulfide is burned in the furnace 4 as a result.

An example is calculated in the following:

During gas desulphurization in a refinery, 12,600 Nm / h of gas with the following composition are generated:

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10700 Nm ³ /H H ₂ S 252 Il ^C 2 ^H 6 1018 It CO ₂ 6 30 Il H ₂ O

This gas is burned with 5350 Nm / h of oxygen corresponding to 25500 Nm / h of air, 10700 kg / h of sulfur and 1070 Nm / h of SO- are produced. The combustion temperature is approx. 1500 C. This gas is cooled down to approx. 320 C in the steam generator and a steam of 30 bar is generated at the corresponding temperature. In the sulfur condenser 3, the gas is further cooled down to approx. 140 ° C. and steam of 0.8 bar and the corresponding temperature is generated in the process. About 10500 kg / h of sulfur are condensed out there. The gas leaving the sulfur condenser 3 is now burned in the furnace 4 with a high proportion of air, a gas with 7.5% SO ₂ and 1.5% O ~ being produced. This gas is cooled in the steam generator, freed of acid mist in a known manner and mixed with air so that a gas with 5.66% SO ₂ and 6.24% O ₂ is available for the subsequent sulfuric acid process. The sulfuric acid is obtained as a 95-98% acid. The exhaust gas exiting from plant 6 should be less than 350 ppm S0 _? contain.

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Claims (2)

24.371.5 Go / Fe 04/20/1977 GHT Society for high temperature reactor technology mbH 5060 Bergisch Gladbach 1 Production of sulfur and sulfuric acid from hydrogen sulfide Expectations 1, Process for obtaining sulfur and sulfuric acid from hydrogen sulfide by combustion with the following Steps: a) Hydrogen sulfide is partially burned in a first furnace with a low proportion of air. b) The heat of combustion is dissipated in a steam generator. c) The elemental sulfur is deposited in a sulfur 'condenser. d) The gases emerging from the sulfur condenser become completely closed with a high proportion of air Burned sulfur dioxide. e) This sulfur dioxide is converted into sulfuric acid in a known manner. 609843/0314 0RK31HAL INSPECTED 2. Plant for carrying out the method according to claim 1, with the following features: a) A bypass pipe branches off before the hydrogen sulfide enters the first furnace away. b) This bypass opens into the second before the gases containing sulfur dioxide enter Oven. - 3 - 809843 / Q3U