JPH01308494A - Removal of hydrogen sulfide from industrial gas - Google Patents

Abstract

PURPOSE: To remove H₂S by feeding an H₂S-containing gas into an absorbing device together with SO₂ and a specific solvent, reacting the H₂S with SO₂ in the solvent, and thereby producing sulfur in the form of coarse crystal be easily separable by gravitation from the solvent.

CONSTITUTION: An H₂S-containing raw gas is fed into a venturi scrabber 1, and at the same time, SO₂ 2 equivalent to the stoichiometric amount and N-methyl-ε- caprolactam(NMC) 4 as a solvent are fed. A suspension is obtained which contains sulfur in the form of coarse crystal produced through reaction of H₂S with SO₂ in the solvent. This suspension is separated from gas phase using a cyclone separator 5, and the desulfurized gas is used as a heating gas. By a pump 6, the sulfur-containing NMC is drawn out of a liquid sump in the separator, fed to a gravitational separating/ sulfur melting device 9 via a heat exchanging device 8, and heated by a steam heater, and meantime the liquid sulfur is collected in the liquid sump in a vessel 9 to be removed. The NMC is put by pressure into the heat exchanging device 8, and a majority of the sensible heat is given to an NMC/sulfur suspension and reaches the venturi scrabber via a cooler 10. The reaction water is removed in the form of steam, and after cooling 11, discarded waste water.

COPYRIGHT: (C)1989,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is useful for removing hydrogen sulfide from industrial gases such as natural gas, coal gasification gas, synthesis gas or waste gas from conventional desulfurization processes. Regarding how to.

BACKGROUND OF THE INVENTION Hydrogen sulfide must be removed from various industrial gases because of its toxic effects on the environment, its corrosive effects and its poisonous effects on many industrial catalysts. A large number of methods or combinations of methods are known in the industry for this purpose.

In many practical applications, hydrogen sulfide is removed from the gas absorptively by a physically or chemically acting solvent and separated from the solvent again using thermal energy.
Gulf Publ, Co. of Hyuston, Texas
, published by F.C. Riesen-feld%A
, L., OHL, "Gas Purification" 2nd edition (1974)]. In this case, an H2S-containing waste gas is produced which, depending on the quality of the raw gas and the type of desulphurization method used, also contains other gas components, which include H2S
The reaction in the conventional Rouss process equipment is technically and energetically difficult, or the hydrogen sulfide content is too low, or the content of higher hydrocarbons in the waste gas is too low. When the temperature is too high, the reaction is blocked.

Furthermore, several methods are known for the removal of hydrogen sulfide, in which hydrogen sulfide is oxidized to elemental sulfur by an aqueous solution containing oxidizing compounds, with the oxidizing compounds being reduced. . Examples of this type of method include, for example, the sulfindo process (H, Mackjinger;
fint Process”: Hydrocarb.

Proc, (1982) 3.98-101),
LO-CAT method (L.

C. Hardison: “112S to S in one device”: Hydrocxarb, Proc.
(1985) pp. 4.70-71] and the Stretford process (Nicklin, T.; "Application of the Stretford process to the purification of natural gas": IGU/A13-
73: 12th World Gas Conference N1zza (1973)
) can be given.

The above-mentioned processes have the disadvantage that these so-called redox compounds have to be oxidized again by an equipment-expensive pneumatic regeneration, that the sulfur precipitates out in extremely fine form due to the aqueous solvent, and that large-volume settling vessels or The need for filtration equipment, the complex chemical absorption solution requiring very strict control of its chemical composition and activity, and the various unavoidable side reactions that lead to harmful saline wastewater; This has disadvantages such as requiring expensive water treatment.

Also known are methods for removing hydrogen sulfide by reaction with sulfur dioxide in various organic solvents, which are catalyzed by H, Fischer; "Reduction of sulfur compound waste from sulfur recovery units": Erdoel. u.

Niohle 27 (1974) 6.292-296
Page, Lynn, S., et al.; “H2 from Coal Gas
Proceedings of the 5th Contractors' Annual Meeting on the Control of Impurities in Coal-Derived Gas Streams, p. 9 (1986)
), DE 21 SO 872, DE 1914425, DE 2313148] or containing sulfuric acid in methanol for the formation of polymeric sulfur (Boland Patent No. 98843). Publication No.) or
Alternatively, it may consist of a mixture of methanol and water (Boland Patent No. 98432).

Requiring the use of a catalyst requires greater control over its chemical composition and activity, while the use of readily volatile methanol as a liquid reaction medium allows for the absorptive recovery of its methanol vapor. conditional on large expenditures.

Also, for example, sulfoxides (West German Patent Application No. 2)
106285), phosphine oxyto (West German Patent Application No. 2106284), derivatives of urea (West German Patent Application No. 2108262), polyglycols (West German Patent Application No. 2108262),
65646) or orthophosphoric acid triamide (
Although methods using organic solvents have been proposed, such as in West German Patent Application No. 2106543), these have never been implemented as large-scale techniques because these solvents are expensive and This is because they are either not fully usable on a large scale or are difficult to handle industrially.

(Problems to be Solved by the Invention) The object of the present invention is to remove hydrogen sulfide from various industrial gases by a one-step process to obtain a crystalline product which can be easily precipitated without the use of an additional catalyst. Such a method produces sulfur and desulfurizes the gas to a range of ppm to O.

The object of the present invention is to remove hydrogen sulfide from various industrial gases in a one-step process and simultaneously produce elemental sulfur.

[Means to solve the problem]

According to the present invention, the above problems are solved as follows.

The crude gas to be desulphurized is transferred to N-methyl-ε-caprolactam (hereinafter referred to as (abbreviated as MMC).

To this crude gas is added a stoichiometric amount of SO2 according to the following reaction equation % (1) immediately before it is fed into the mass exchange device described above. However, it is also possible to introduce this required amount of SO2 into the NMC in an additional, separate absorption device, so that the MMC preloaded with SO2 reaches the H2S absorption device. It is. NMC is SO2 and H2
It is an excellent solvent for S gas. At the same time, the inventors also discovered that MMC exhibits a catalytic effect on the above reaction (1).

Due to the cyclic structure of the compound and the lactam groups contained therein, due to the catalytic action of NMC, no induction period appears as in the case of other organic and inorganic solvents, and therefore no additional catalyst is required. It's unnecessary. As a result, only very short contact times are required for the substance exchange when stoichiometrically dosed, and no leakage of l(, S 2 and/or S02 occurs).

(Effect) This reaction system has several ppm of H2S and S02.
suitable for ensuring the final content of m. In the reaction, coarse-grained crystalline sulfur is formed, which can be completely separated from the solvent by precipitation only under industrial conditions in a residence time of up to 2 minutes.

Due to the good settling properties of sulfur, strong turbulence can be created by using venturi flappers or jet scrubbers in the absorption system, which would otherwise result in absorption by the resulting sulfur. Premature precipitation of sulfur, which would lead to clogging of the equipment, is prevented.

Separation of sulfur from NMC is preferably carried out at a temperature level of 130° C., since liquid sulfur has only a slight viscosity at this temperature and a sufficient difference in specific gravity appears between MMC and sulfur for gravitational separation. , and the reaction water produced according to the above formula (1) can be removed from the system by simple pressure control. 15% by weight of MMC
Water contents above must be avoided, since otherwise the resulting sulfur will be present in the MMC in colloidal form, which is difficult to remove from the MMC.

〔Example〕

The present invention will be explained in more detail below with reference to Examples.

During the deoxidation and conditioning of largely inert petroleum-entrained gases by physical adsorption methods, waste gases are produced with the following parameters: Gas volume 10,000 a+3/hr Gas pressure
0.2 peak a (absolute) Temperature 30°C Composition (mole ratio) H2S 0.05 N2G,03 CO□ 0.68 CH40,15 C,860,03 C3HIS O,03 C,H,. Because of the low content of 0.02 C, 0.01 H2S and the relatively high concentration of higher hydrocarbons, this waste gas cannot be processed in a conventional Claus process plant. Incineration is also unacceptable SO
2 is similarly excluded due to the release of .

A flow sheet of the method for removing H2S from the gases described above is shown in FIG.

The crude gas is fed into the venturi flapper 1 through the crude gas conduit. SO2 from the SO2 storage tank (3) via conduit 2 enters the crude gas via a metering control device 715.3
kg/hr. 15 II+3/hr of NMC is fed into the venturi flapper via line 4 as absorption medium as well as reaction medium. At the outlet of the Venturis flapper a suspension of coarse crystalline sulfur in NMC is present in the liquid phase. This suspension is separated from the gas phase by a cyclone separator (5). The desulfurized gas is then used as heating gas for other processes.

The sulfur-containing NMC is extracted from the cyclone separator sump by a pump (6) and using a level controller. A liquid bypass (7) prevents premature precipitation of sulfur in the cyclone separator sump.

The MMC passes through the heat transfer device (8) and receives the gravity component Il! / into a sulfur melting combination device (9).

Here, a temperature of 130°C is set using a steam heating device. Liquid sulfur in the liquid reservoir of container (9) is 1873
kg/hr. M from the center part
The MC is forced into the heat transfer device (8), where it imparts a large part of its heat sensitivity to the NMC/sulfur suspension and passes through the cooler (10) again to the Venturis flapper.

By controlling the pressure, the reaction water is removed from the system as steam and becomes waste water after condensing in the cooler (11).

The resulting liquid sulfur can be sold as a product in the form of liquid sulfur or flaky sulfur.

[Brief explanation of the drawing]

The accompanying FIG. 1 shows a flow sheet of an embodiment of an apparatus for carrying out the method of the invention. 1... Venturis flapper 2.4... Conduit 3... SO□ storage tank 5... Cyclone separator 6... Pump 7... Liquid bypass 8...
Heat transfer device 9...Gravity separation/sulfur melting device 10.11...Cooler

Claims (4)

[Claims] (1) A method for removing hydrogen sulfide from industrial gas or natural gas, in which the hydrogen sulfide-containing gas is sent to an absorption device together with a stoichiometric amount of sulfur dioxide and N-methyl-ε-caprolactam as a solvent. , in which the above N-methyl-ε
- A process as described above, characterized in that from caprolactam a coarsely crystalline sulfur is formed which can be easily separated by gravity separation. (2) separation of sulfur from N-methyl-ε-caprolactam solvent in a temperature range of 120-130°C;
2. The method of claim 1, thereby leading to the formation of liquid sulfur. 3. The process of claims 1 and 2, wherein the reaction water from the sulfur separation process is removed from the system in the form of steam by expansion vacuum at a temperature of about 130°C. 4. Process according to claim 1, characterized in that the N-methyl-ε-caprolactam is loaded with the required amount of SO_2 in a separate absorption device before it is fed into the absorption device.