DD269858A1 - METHOD FOR GENERATING URBAN GAS FROM SULFUR HYDROGEN-BASED GASES - Google Patents

Abstract

The invention relates to a process for the production of city gas from hydrogen sulfide-containing crude gases, preferably from the degassing and gasification of solid fuels. The essential feature of the invention is that a desulfurization gas enriched with hydrogen sulfide and carbon dioxide is mixed from a gas purification process with a sulfuric acid stoichiometric amount of sulfur dioxide and intimately contacted with N-methyl-E-caprolactam at normal temperature, wherein sulfur in solid form anfaellt and that in this way largely freed from hydrogen sulfide but CO2-rich desorption gas with treated raw gas and a high-caliber carburizing gas, such as natural gas or liquid gas, is mixed to a standard city gas.

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a process for the production of city gas from hydrogen sulfide-containing raw gases, preferably from the degassing or gasification of solid fuels.

Characteristic of the known state of the art

Various methods are known according to which city gas is produced on the basis of hydrogen sulfide-containing raw gases from the deaeration or gasification of solid fuels.

This is done by the raw gas is freed by adsorptive or absorptive cleaning method of hydrogen sulfide and other undesirable components and then by mixing with nitrogen or nitrogen-rich natural or synthetic gases and a high calorific gas such as natural gas or propane-butane mixtures a city gas according to the quality standards is produced. The presence of nitrogen and / or carbon dioxide in town gas is unavoidable because of the setting of certain firing quality values.

It is characteristic of the mentioned gas purification processes that regeneration processes become necessary, as a result of which hydrogen sulphide-enriched desorption gases are produced. Frequently, in a further process stage, such as a Sulfosolvananlage, this desorption gas selectively hydrogen sulfide be removed, in turn, a desorption gas is obtained which has an even higher concentration of hydrogen sulfide. As a result, it can be worked up to elemental sulfur in the subsequent sulfur recovery plant, the so-called Claus plant. The largely freed from hydrogen sulphide desorption gases are either flared or used as an additional fuel, which is due to the low calorific value and because of the still undesirably high residual hydrogen sulfide in the consumers rather a burden than a benefit arises.

It can be seen that the entire technology is very complex both in terms of the treatment of desorption gases and in terms of sulfur recovery. In addition, the said desorption gases are not suitable because of the mentioned residual amounts of hydrogen sulfide as an inert-rich mixed component for urban gas production. Their combustion leads to significant environmental pollution.

The above drawbacks of the known technologies do not change even if a so-called selective washing process is used to remove the hydrogen sulphide from the raw gas. Then the process stage for hydrogen sulphide accumulation in the desorption gas, for example a sulphosolvanisation plant, may be omitted. On the other hand, this desorption gas, which reaches the Claus plant, has a much lower hydrogen sulfide concentration than in the first case, which leads to increased costs in obtaining sulfur in the Claus plant. Environmental pollution and loss of combustible substance for urban gas production remain.

Object of the invention

The object of the invention is to utilize the hydrogen sulfide-rich desorption gas obtained in the customary gas purification processes as a necessary inert gas component for urban gas production and thus to enable production of a standard-compliant urban gas while dispensing with nitrogen-rich natural gases or nitrogen. Thus, the combustible gas components contained in the desorption gas should be fed to a meaningful use. The previously caused environmental pollution during the combustion of the treated desorption gas should be omitted. At the same time the extraction of elemental sulfur technologically and economically advantageous than previously customary.

Explanation of the essence of the invention

The object of the invention is to allow the generation of town gas based on hydrogen sulfide-containing crude gases waiving nitrogenous natural or synthetic gases or nitrogen after virtually complete removal of the hydrogen sulfide from the desorption gas of the gas cleaning process by the admixture, doing its combustible components for the To make city gas production harnessed to avoid the environmental impact of the previously customary combustion of the treated but still undesirable residual amounts of hydrogen sulfide-containing desorption and to achieve a technologically and economically favorable extraction of elemental sulfur by eliminating such process stages as Sulfosolvan- and Claus plant.

The essence of the invention is that the sulfuric acid-enriched desorption gas inevitably obtained in the purification of the raw gas of hydrogen sulfide in a methanol-low-temperature washing desorption gas to a sulfuric acid stoichiometric amount of sulfur dioxide according to the reaction

2H ₂ S + SOj-> 3S + 2H ₂ O

is added and that in the presence of a liquid absorption Katalyeators the gaseous sulfur compounds are reacted in the dissolved state at normal temperature to elemental sulfur in solid form.

It has been found that N-methyl-e-caprolactam (NMC) is the most suitable liquid absorbent with catalytic activity. The gas mixture is applied in known scrubbers under pressure or without pressure with this NMC, wherein H ₂ S and SO ₂ react spontaneously to form sulfur with each other. Thereafter, the elemental sulfur is separated from the solvent and the resulting water in the molten state and fed to the economic use. The so largely freed from hydrogen sulfide but CO ₂ -rich desorption gas is mixed with the treated original raw gas and a calorific value karburiergas, z. As natural gas or liquefied petroleum gas, mixed in such a ratio that according to calorific value, Wobbezahl and Üichteververhältnis and other quality standards in accordance with city gas. The addition of sulfur dioxide to the desorption gas can also be carried out in excess with respect to the hydrogen sulfide contained therein, if a particularly low residual content of hydrogen sulfide in the desorption gas is required. However, then the excess sulfur dioxide must be washed out again.

A> guide example

The invention will be explained below with reference to an embodiment with reference to FIG. 1:

A mixture of raw hydrogen sulfide-containing raw gases from a fixed-bed pressure gasification plant 1, a lignite high-temperature coking plant 2 and a dust-pressure gasification plant 3, all based on brown coal, is fed to a methanol cryogenic temperature wash 4.

From the desorber 5 of the detergent cycle of the low temperature washing is released by expansion desorption gas, which is highly hydrogen sulfide ig, and fed via a compressor 6 a Venturi scrubber 7 and then a scrubbing column 8 at a pressure of 3 MPa. Previously, a stoichiometric amount of sulfur dioxide generated in elemental sulfur combustor 9 was added to the desorbing gas.

This gas mixture is intensively contacted in Venturi scrubber 7 and in column 8 with N-methyl-E-caprolactam (NMC), which acts as a catalytic absorbent. In this case, the gaseous sulfur compounds turn into elemental sulfur, which collects together with the solvent and the water formed at the bottom of the column 8 and from there into the combined settling tank / sulfur melter 11 is passed. The sulfur is withdrawn liquid from the lower part of the container 11. After the water has been separated off, the regenerated NMC is returned to the Venturi scrubber 7 and the column 8 via a pump 10.

The freed from hydrogen sulfide to very small residual amounts but CO ₂ -rich desorption gas passes from the top of the column 8 via a compressor 12 after appropriate pre- and post-cooling to a gas mixing station 13, where eb in pre-calculated ratio with the clean gas from the low-temperature washing, other hydrogen-containing Pure gases and imported gas (IEG) is mixed to a town gas according to TGL 28049.

In terms of numbers, this is as follows, with the crude gas entering the cryogenic scrubbing coming to different parts from the fixed bed coal pressure gasification (CO), from the brown coal high temperature coking (BHT) and from the dust pressure gasification (SDV).

KDV BHT SDV

Raw gas / fieingas-Ratio. m ³ / m ³ 1.63 1.36 1.10 raw gas 10 ³ m ³ / d 7824 2856 440 clean gas 10 ³ m ³ / d 4800 2100 400 desorption 10 ³ nr7d 3024 756 40 H ₂ S in the raw gas g / m ³ 3.5 7 5 kg / d 27384 19992 2 200 H ₂ S in the clean gas mg / m ³ 1 1 1 kg / d 4.8 2.1 0.4 H ₂ S in the desorption gas kg / d 27379 19990 2200 m ³ iN / d 17788 12987 1429

From this, the demand for SO ₂ and the net production of sulfur are derived: H ₂ S seizures m ³ iN / d 32204 SOj requirement m ³ iN / d 15920 S-Bruttoprod. kg / d 69946 S-Verbrauchfür SO ₂ product. kg / d 23315 S-Net product. kg / d 46631 In this case, according to the stoichiometric reaction equation, the desorption gas was about 50% of the volume of it

contained hydrogen sulfide added to sulfur dioxide.

Thereafter, the mixture is made to city gas using other gas components as follows: Clean gas from low-temperature washing 10 ³ m ³ / d 7300

of which: fromKDV 10 ³ m ³ / d (4800)

from BHT 10 ³ m ³ / d (2100)

from SDV 10 ³ ITiVd (400)

Other clean gas 10 ³ In ³ Zd 1500 Importer gas 10 ³ m ³ / d 1890 Concent. Desorption gas 10 ³ m ³ / d 1900 Town gas 10 ³ In ³ Zd 12590 Town gas quality values: Calorific value MJZm ³ LN. 17.9 Calorific value MJ / m ^{3 in} 15.3 Lower Wobbe Number MJZm ³ LN. 19.3 Density ratio - 0.625

Core length s / m 4.8 This means that the town gas complies with TGL 28049.

Claims (2)

1. A process for the production of city gas from hydrogen sulfidehaltipen raw gases, preferably from the degassing and gasification of solid fuels, characterized in that the originating from a absorptive or adsorptive process for crude gas cleaning hydrogen sulfide and carbon dioxide-rich desorption gas with respect to the hydrogen sulfide contained therein stoichiometric amount of sulfur dioxide is added and that thereafter this gas mixture is brought into intimate contact with N-methyl-e-caprolactam as a liquid absorbent with catalytic action at normal temperature and that the elemental sulfur thus formed by the liquid which is recycled to the washing cycle , Is separated and that the almost completely freed from hydrogen sulfide but CO ₂ -rich desorption gas is mixed with the addition of a high calorificational carburizing gas in such a ratio with the treated original raw gas that a normge right city gas arises. 2. The method according to claim 1, characterized in that a complete reaction of the hydrogen sulfide is sought by a superstoichiometric amount of sulfur dioxide and that the remaining excess of sulfur dioxide is removed by a Nachwäsche from the treated desorption gas,