JPH03161023A - Treatment of hydrogen sulfide-containing non-condensed gas - Google Patents

Abstract

PURPOSE:To remove high or low concn. H2S with high efficiency by burning hydrogen sulfide-containing non-condensed gas to convert H2S in the gas to SO2, and cooling the SO2-containing gas under pressure to liquefy SO2 while discharging the remaining non-condensed gas out of the system. CONSTITUTION:The hydrogen sulfide-containing non-condensed gas discharged from a geothermal energy utilizing plant through piping 11 and a condenser 12 is burnt in a combustor 28 to convert H2S in the gas to SO2. This SO2- containing gas is cooled by a cooler 31 and subsequently compressed by a compressor 36 to be guided to a liquefying device 38 to be compressed, cooled and liquefied and introduced into a SO2 reservoir 44 from the bottom part 42 of the device 38 to be recovered and stored as liquid SO2 to be utilized as an industrial raw material. The non-condensed gas from which SO2 is separated in the liquefying device 38 is discharged out of the system from piping 45. As a result, H2S from low concn. to high concn. can be removed with high efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for treating non-condensable gas containing hydrogen sulfide, which is applied to geothermal power plants and other geothermal utilization plants.

[Conventional technology]

Generally, geothermal power generation is performed by extracting steam ejected from underground together with hot water and passing this steam through a turbine as a working fluid to generate electricity. The steam after passing through the turbine is condensed with cooling water in a condenser. At this time, in order to reduce the pressure inside the condenser to the saturated pressure of the condensed water, the vacuum pump performs extraction.
．． The composition is usually more than 90% carbon dioxide, with about a few hydrogen sulfide, traces of nitrogen gas, oxygen gas, and hydrogen gas. It consists of etc. This non-condensable gas is currently being released, but in recent years, as the development of geothermal energy has been gaining momentum around the world, concerns have been raised about the impact of hydrogen sulfide on ecosystems such as animals and plants. There is a tendency for this to become regulated in the next few years.

On the other hand, many methods have been developed and put into practical use to treat hydrogen sulfide in waste gas discharged from oil refining, natural gas, city gas, and other industries. 1) What is the basic reaction based on the Claus process? There are many applied processes such as the Claus process, Parsons sulfur recovery process, Ude sulfur recovery process, Combrymo sulfur recovery process, Amoco process, etc. O These basic reactions are as follows: H, S (D 1/3 is oxidized to SO, and the skeleton SO is reacted with the remaining poH, S to form SO.
It is used to recover a simple substance and is expressed by the following formula.

1/3 H, S + 1/2 0, - 1/3 So
, + 1/3 H,0 (oxidation by combustion) 2/3 H,S + 1/3 8024 S + 2/
3 H,0 (decomposition by catalyst ■) (2) Absorption method (1) Seaboard type desulfurization process H, S is absorbed into soda ash solution in an absorption tower, and H, 8 is diffused by blowing air in a regeneration tower. The regenerated soda ash solution is recycled to the absorption tower, and the diffused condensed H and S are treated by the above-mentioned Claus method or the like.

The above-mentioned Seaboard is a method in which H and 8 are absorbed by a soda ash solution κ in a Mitsubishi Chemical absorption tower, and H and S are liberated and recovered as 8 using an iron oxide catalyst suspended in the liquid in a regeneration tower. This is an improved method of Eq., and requires an S simple (II) r-transformer.

(1) H and S are adsorbed on activated carbon dispersed in the BASF process liquid. The adsorbed 9H and 8 are oxidized with air and S is separated. This S is extracted from activated 5 carbon from ammonia sulfide κ, and activated carbon is r
Separate, collect and reuse using a filter.

Qv) I,F. P. ANTIPOL Process (F
UGAPOL150) H and S are absorbed into ammonia solution in an absorption tower, NH, and H,8 are diffused in a stripping tower, NH is recovered and reused, and H and S are subjected to Claus reaction in a reaction tower. , S (liquid) is recovered 0 (v) SHELL ADIP po-t=x absorption tower absorbs H, 8 into the aminodiisopropanol acidic solution, H, 8 is diffused in the regeneration tower, and Claus reaction is performed. H in the furnace
, S and recover S.

(3) Dry process This method is suitable for removing trace amounts of hydrogen sulfide for secondary desulfurization in city gas production, etc., and the method involves adsorbing H and S with an iron oxide adsorbent K in a desulfurization tower. To regenerate this adsorbent, when water is sprayed and exposed to the atmosphere, iron sulfide is regenerated into iron oxide, and elemental S is precipitated on the surface. [Problem to be solved by the invention] However, these existing There are the following problems in applying the above-mentioned process to the treatment of non-condensable gas in geothermal power plants: (a) The concentration of the gas to which the dry process is applicable is extremely low, at 1,000 ppm or less; It may also be necessary to regenerate and replenish the adsorbent.

(b) Other methods (1) Both have advantages when the amount of gas is large, but geothermal power plants usually emit only a small amount of gas, and in the case of such a small amount of gas, it is disadvantageous. Appropriate 0 (It) The plant is complex and requires manpower. In geothermal power plants, only a few operators die even at power plants of 10,000 kW or more, and it is a simple process because the temperature is low and low pressure (~200°C, ~2 oata) compared to normal power plants. It is necessary.

(1) Construction costs are high. For example, the Claus method requires about 10% of the total construction cost of a geothermal power plant, and when processing diluted gas in a trench, it must be condensed in advance into several quantities, and the construction cost of the equipment required for this is added. Ru.

■ Running costs are relatively high.

The present invention has been made in view of the above points, and includes (1)
(2) H and S contained in the gas can be treated at low to high concentrations; (3) Existing simple processes can be used; (4) )
The present invention aims to provide a method for processing non-condensable gas containing hydrogen sulfide that satisfies the following requirements: (5) low construction costs; (6) low running costs; less manpower required for operation;

[Means to solve the problem]

That is, the method for treating uncondensed gas containing hydrogen sulfide of the present invention is as follows: (1) Burning uncondensed gas containing hydrogen sulfide discharged from a geothermal utilization plant to convert it into hydrogen sulfide, SO, in the gas; 2) Pressurize and cool the gas containing SO.
, and (3) the remaining non-condensable gas was discharged outside the system.

[Effect]

H,8 burns easily in the presence of air and burns 80 with high efficiency.
．． It can convert 4C, and has the property of self-combusting due to the heat of combustion at a certain concentration or higher. In the present invention, by burning hydrogen sulfide in the hydrogen sulfide-containing noncondensable gas discharged from a geothermal utilization plant, it is easily and highly efficiently converted into SO.

SO, is easily liquefied by pressurization and cooling operations at a temperature near room temperature. Therefore, by pressurizing and cooling the gas containing SO, it is easily converted into other non-condensable gas components such as CO2, N,, O! , H, etc. can be highly separated.

Therefore, according to the present invention, hydrogen sulfide can be converted into SO, liquefied, and easily separated from other non-condensable gas components with high efficiency, and this non-condensable gas is not subject to any regulations. Can be released into the atmosphere.

〔Example〕

FIG. 1 is a system diagram of an embodiment in which the method of the present invention is applied to a conventional geothermal power plant.

In the attached drawing κ, hot water ejected from a hot water well 1 passes through a pipe 2 and reaches a gas-liquid separator 3, where it is separated into steam and hot water. Of these, the hot water is returned to the ground via a pipe 4, a hot water return pump 5, a pipe 6, and a return well 7. On the other hand, the steam reaches the turbine 9 via the pipe 8, moves the turbine 9, and generates electricity by the generator 1o driven by the turbine 9.

The steam leaving the turbine 9 passes through the pipe 11 to the condenser. Nsa 1
Reach 2. Cooling water cooled by a cooling tower 13 is sent to the condenser 12 via a pipe 14, a cooling water pump 15, and a pipe 16.

When the condenser 12 is of a direct contact type, the steam is cooled by direct contact with the cooling water inside the condenser 12, and becomes hot water. The hot water passes through piping 17 to hot water tank l8.
The water is temporarily stored in the pipe 19, the hot water pump 20,
The water is sent to the cooling tower 13 via piping 21 and is used for circulation as cooling water.

In the cooling tower 13, cooling water is replenished from the piping 22 as necessary and is blown down from the piping 23 to balance the water balance within the system and at the same time prevent some concentration from dissolving.

When the condenser 12 is a surface type, normally cooling water passes through a large number of tube groups provided in the condenser 12 and reaches the hot water cylinder 18 via piping 17, while steam passes through the outside of the tube group. The liquid water is cooled inside, becomes liquid water, and is taken out from the pipe 24.

Inside, this water contains a small amount of non-condensable gas (H, S, CO, etc.)
Does it contain almost no other inorganic salts? in,
It is purified by air treatment and used for various purposes.

Further, the non-condensable gas that has entered the condenser 2 along with the above steam is sent to the combustor 28 via the piping 25, the bleed pump 26, and the piping 27, and the non-condensable gas is transported by the air introduced from the piping 29. H,8 contained therein is combusted.

At this time, if the concentration of H and S in the non-condensable gas is low, it is necessary to use an auxiliary parner to heat and burn it in a flame, but if the concentration of H and S is high, especially if the In this case, an auxiliary burner is required only at the time of ignition, and combustion can then be maintained using its own combustion heat. During this combustion, H,8 is converted to SO2 according to the reaction formula below.

3 H, S + TO, - H, 0 + So
I am guided by 1. When the cooler 31 is buttoned, the cooling water is discharged from the pipe 32 to the outside through the internal cooling pipe 33 and the pipe 34, and during this time, the combustion waste gas introduced into the cooler 31 through the pipe 30 is cooled to around room temperature. . This cooled combustion waste gas passes through a pipe 35, is pressurized and compressed by a compressor 36, and is then introduced into a liquefier 38 through a pipe 37. The liquefier 38 is equipped with a cooling water inlet pipe 39, an internal cooling pipe 40, and an outlet pipe 41 for cooling the pressurized and compressed combustion waste gas, and the SO in the combustion waste gas is At 38, it is pressurized, cooled, and liquefied, and is deposited in the bottom section 42 of the same cooler.

The relationship between liquefaction pressure and temperature near normal temperature is as follows.

Temperature ('C) 20 30 40 Liquefaction pressure (atw) 3.23 4.50
6.13 Therefore, when the temperature inside the cooler 38 is set to 20° C., the inside of the system is pressurized by the compressor 36 to 3.23 atw. Cot other than SO2, 0,,
N! Since gases such as SO and H2 do not liquefy in these temperature and pressure ranges and exist in a gaseous state, it is easy to liquefy and separate only SO.

The S02 liquefied in the cooler 38 is introduced from the cooler bottom 42 through the pipe 43 to the reservoir 44, where it becomes liquid SO,
Collected and stored as nylon raw material? On the other hand, the non-condensable gas from which SO■ has been separated in the cooler 38 is discharged from the pipe 45 to the outside of the thread.

As mentioned above, in this example, hydrogen sulfide in the hydrogen sulfide-containing noncondensable gas discharged from a geothermal utilization plant is converted to SO, and this is liquefied by cooling and pressurizing.
Hydrogen sulfide in the non-condensable gas can be easily separated and removed with high efficiency, and the remaining non-condensable gas that does not contain hydrogen sulfide can be discharged to the outside.

In addition, the device for carrying out this embodiment is a compact device consisting of a combustor 28, a cooler 31, a liquefier 38, etc.
Moreover, its manufacturing cost is low.

In the above embodiment, when the H2S concentration in the non-condensable gas is low, the auxiliary burner is used to heat and combust it, but H and S are concentrated using a pressure swing type gas adsorption device and then combusted. You can do it like this.

〔Effect of the invention〕

The present invention can have the following effects.

? 1) H in non-condensable gas containing hydrogen sulfide discharged from geothermal utilization plants! It is possible to convert S into SO through combustion, and then pressurize and cool it to separate and recover SO as a liquid. Moreover, with such a relatively simple process, it is possible to convert SO from low to high concentrations. H,8 can be removed with high efficiency, so it is excellent to apply to geothermal utilization plants that are usually located in relatively remote areas.
2) Fuel for auxiliary burner for combustion of H,8 (H,S
(3) Recovered SO can be used for sulfuric acid, nylon, and other industrial purposes. It is widely demanded as a basic raw material for industrial use, and is convenient for storage and transportation because it liquefies at low pressure.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram of an embodiment of the present invention.
・Hot water well, 3... Gas-liquid separator, 7... Reduction well, 9... Turbine, 10... Generator, 1
2... Condenser, 3... Cooling tower, 18... Hot water tank, 8... Combustor, 31... Cooler, 6...
Compressor, 38... Liquefier, 4... S02 reservoir.

Claims (1)

[Claims] The hydrogen sulfide-containing non-condensable gas discharged from a geothermal utilization plant is combusted to convert the hydrogen sulfide in the gas into SO_2, and this SO_2-containing gas is pressurized and cooled to produce SO_2.
A method for treating non-condensable gas containing hydrogen sulfide, which comprises liquefying the hydrogen sulfide and discharging the remaining non-condensable gas to the outside of the system.