JPH0631350B2 - Solid-gas contact reactor - Google Patents

Description

FIELD OF THE INVENTION The present invention relates to sulfur compounds, especially hydrogen sulfide, contained in a reducing gas mixture at elevated temperatures containing soot, such as the product gas of a coal gasification process. The present invention relates to a solid-gas contact reaction device capable of performing stable operation without pressure loss increase or blockage due to dust adhesion when adsorbing and removing, and capable of efficiently performing a regeneration reaction of the adsorbent that has captured a sulfur compound.

(Prior art) In recent years, development of utilization technology of inferior residue or coal etc. has been promoted as measures against rising oil price and heavy imported crude oil. A typical example is a method in which the generated gas is used for power generation or as a fuel or a synthetic raw material.

However, this gasification product gas contains hydrogen sulfide of several hundreds to several thousand ppm, which varies depending on the raw material coal or heavy oil, and the hydrogen sulfide is for pollution prevention or corrosion prevention of downstream equipment, It needs to be removed.

As a means for dryly removing hydrogen sulfide in the produced gas, solid gas such as a fixed bed, a moving bed or a fluidized bed to which a small spherical adsorbent of a metal oxide such as Fe, Zn, Mo, Cu or W is applied. Although a catalytic reactor is used, the gasification product gas contains a large amount of soot and dust such as unburned carbon (char) and tar. Therefore, in a fixed bed to which a conventional small spherical adsorbent is applied, it scatters. It is not preferable because clogging is caused by the dust and dirt, and the pressure loss increases, which hinders the operation of the gasification furnace. Further, in a moving bed in which the adsorbent is moved to prevent an increase in pressure loss, there is a problem in stable operation for a long time, which makes the device complicated. Further, in the fluidized bed, there are drawbacks such as abrasion and scattering of the adsorbent. Therefore, the present inventors have overcome the drawbacks of the above-mentioned conventional apparatus, have no increase in pressure loss over time, and have a compact size, which is economical, and has a high practicality. An application has already been filed for a solid-gas contact reaction device characterized in that a large number of agents are arranged such that the adsorption surface is parallel to the gas flow (Japanese Patent Application No. 58-223250).

(Problems to be Solved by the Present Invention) The present invention captures a sulfur compound in order to take advantage of the feature of the solid-gas contact reaction device in which the processing gas is passed through the adsorbent composed of the tubular structure in parallel flow. Provided is a solid-gas contact reaction apparatus capable of suppressing heat generation during regeneration reaction of the adsorbent as much as possible, preventing performance deterioration and damage due to local heating of the adsorbent, and achieving a stable desulfurization method from high-temperature reducing gas. It is a thing.

(Means for Solving Problems) The present invention relates to a sulfur compound contained in a high-temperature reducing gas obtained by gasification of coal, heavy oil, or the like as an adsorbent containing a metal oxide as a main component. Desulfurization method in which the adsorbent is adsorbed and removed by reusing the adsorbent repeatedly, and the adsorbent consisting of tubular, honeycomb, and plate-like structures is arranged in parallel so as to be parallel to the gas flow. This is carried out in a reactor, and by switching the gas flow directions of the adsorption and regeneration reactions, local heat generation during the regeneration reaction is suppressed and the performance of the adsorbent is maintained.

That is, the present invention provides a device having a tubular structure in which a sulfur compound contained in a high-temperature reducing gas is adsorbed and removed by an adsorbent containing a metal oxide as a main component, and the adsorbent is regenerated for repeated use. Solid gas characterized by arranging a large number of adsorbents composed of a body so that the adsorption surface is parallel to the gas flow, and enabling the gas flow directions during adsorption and regeneration to be opposite. It is a catalytic reactor.

In the present invention, sulfur compounds in a high-temperature reducing gas obtained by gasification of coal, heavy oil, etc., particularly hydrogen sulfide, are adsorbed on metal oxides such as Fe, Zn, Mo, Mn, Cu, W. As a chemical agent, the reaction is carried out at 250 to 450 ° C., the sulfide is trapped inside the adsorbent, and COS as an impurity also partially reacts and removes HCN. The reaction formula by H ₂ gas for Fe is as follows. Is the street.

Fe ₂ O ₃ + H ₂ → ₂ FeO + H ₂ O FeO + H ₂ S → FeS + H ₂ O MCN + H ₂ O → NH ₃ + CO COS + H ₂ O → CO ₂ + H ₂ S By arranging the tubular, honeycomb, or plate-like structure so that the oxygen-containing gas flows from the direction opposite to the gas flow direction during adsorption, the performance of the adsorbent is maintained and uniform heat is generated inside the reactor. Characterized by maintaining the distribution, in forming the metal oxide of the adsorbent, the formation of the oxide itself, or the metal in the heat-resistant porous material such as titania, silica, alumina or zeolite. It can be carried out by various methods such as supporting an oxide and forming a structure so that the gas flows are parallel flows.

Hereinafter, the device of the present invention will be described in detail based on FIG. 1 showing an embodiment.

In FIG. 1, coal 1 is partially combusted and gasified in a gas furnace 3 with a small amount of air or oxygen 2 to obtain a gasified gas 4 containing H ₂ and CO as main components. It is used as a substitute for petroleum or natural gas, as a fuel for companion gas turbines, city gas, etc., or as a synthetic raw material for methanol, ammonia, or petrochemicals.

The gasification gas 4 varies depending on the type of coal and the gasification conditions, but is several tens to several thousand ppm of H ₂ S, COS, NH ₄ , and 2
It contains 0 to 40 g / Nm ³ of soot and dust, and the temperature is 250 to 50 because heat is recovered by a steam heater at the outlet of the gasification furnace 3.
0 ℃, the pressure depends on the type of gas furnace 3, but normal pressure ~
25 ata.

In the present invention, first, the dust removal device 5 such as a cyclone is used to remove the coarse particle dust 17, and the gasification gas 6 is fed to Fe, Zn, Mo,
H ₂ S is adsorbed and removed as a sulfide in a reactor 7 filled with an adsorbent 8 made of a metal oxide such as Mn, Cu or W.

The reaction formula when Fe oxide is used as the absorber is as follows: 3Fe ₂ O ₃ + H ₂ → 2Fe ₃ O ₄ + H ₂ O 3H ₂ S + Fe ₃ O ₄ + H ₂ → 3FeS + 4H ₂ O HCN + H ₂ O → NH ₃ + CO COS + H ₂ O → CO ₂ + H ₂ S Impurities such as HCN and COS are also partially reacted and removed.

The reaction temperature is 250 to 450 ° C., SV value (gas flow rate Nm ³
/ H / adsorbent capacity m ³ ) is 1000 to 20,0001 /
At about h, 90 to 95% or more of H ₂ S in the gas is removed.

In the present invention, as the shape of the absorbent, a tubular structure is adopted, and a large number of the absorbents are arranged in parallel to the gas flow. There is no pressure drop increase due to soot and dust found in fixed beds, moving beds and reactors where agents are applied, stable operation is possible, and the wear loss found in conventional fluidized bed reactors is also small, economically Can be advantageous.

The reactor 7 adopts the multi-column system in FIG. 1, but this is for regenerating and activating the adsorbent deteriorated by the adsorption of H ₂ S and the like by the switching system.

Next, the treated gas 9 is subjected to a fine dust removal device 10 such as a Granular bed method to remove fine dust 11 and converted into a clean gas 12 to be used as a gas turbine fuel or a raw material for synthesis gas.

On the other hand, when the packed adsorbent in the reactor 7 reaches saturation due to the adsorbed H ₂ S, air or oxygen 13 is supplied to the reactor to perform a roasting reaction as shown in the following formula, At the same time that the agent is regenerated, a rich SO ₂ gas 14 is obtained.

4FeS + 7O ₂ → 2Fe ₂ O ₃ + 4SO ₂ 4Fe ₃ O ₄ + O ₂ → 6Fe ₂ O _{3 The} above reaction is an exothermic reaction, and air or (and) oxygen 13
As shown in FIG. 1, the outlet gas 14 is circulated in the path 15 while the required amount of air or / and oxygen is uniformly supplied to the whole at a low concentration. In addition to controlling the temperature, the gas flow direction is opposite to that of the adsorption reaction, and the regeneration reaction proceeds slowly from the side with the smaller H ₂ S adsorption amount.

The regeneration temperature is 250 to 600 ° C, and the adsorbed S
Most of the CO ₂ is emitted, but high concentration of SO ₂
When the gas is diffused and a rapid exothermic reaction occurs, the gas is heated above the heat resistant temperature of the adsorbent and the performance is deactivated due to the change in the crystal structure of the adsorbent. The concentrated SO ₂ gas is passed through the route 16 and used as it is as a raw material for producing sulfuric acid or the like, or is guided to a step of recovering it as elemental sulfur.

Hereinafter, the effects of the present invention will be specifically described with reference to examples.

(Example 1) A gasified gas containing 3000 ppm of H ₂ S obtained by gasification of coal was passed through a multi-stage cyclone to remove about 3 parts of dust.
The adsorption test of H ₂ S was carried out at a temperature of 400 ° C. with the amount of 00 mg / Nm ³ introduced into the reactor of the present invention described below.

FIG. 2 shows the structures of the reactor and adsorbent used in this Example 1.

In the figure, reference numeral 1 is a reaction device filled with an adsorbent for a tubular structure, and the tubular adsorbent 2 is filled in two stages inside. The gasification gas 3 enters from one side of the adsorption layer, hydrogen sulfide is adsorbed inside the adsorption layer, and is discharged out of the system as a purified gas 4.

The tubular adsorbent 2 has a shape such as a square shape, a hexagonal shape, and a triangular shape. In this embodiment, Fe ₂ O having a square (lattice) pore diameter (pitch) of 4.5 mm and a wall thickness of 1.2 mm. _A combination of ₃ type adsorbents, each of which has a tubular adsorbent size of ₁ , 2, 2 ₂ , 2 _3, ... Is.

In such a tubular adsorbent, the gas flow is parallel to the adsorption surface, and there is no gas flow that presses dust against the adsorption surface, so even if dust adheres to the surface, the shearing force of the gas flow Therefore, it is re-scattered, no increase in the adhesion of dust and dust is observed, the pressure loss is hardly increased, and the stable operation of the plant becomes possible. Further, there is no complicated operation for moving the adsorbent, and there is little wear, which is economically advantageous.

In this way, the H ₂ S concentration at the adsorption outlet becomes 100 ppm,
After performing the adsorption reaction until the breakthrough is reached, the regeneration gas (oxygen gas 1%, nitrogen gas 99%) flows in the same direction as the gasification gas flow at the reactor inlet temperature of 500 ° C. FIG. 3 shows the results of measuring the temperature distribution of the adsorbent in the case of the above, in the flow direction of the regeneration gas and in the cross section.

In the present example, in which the gas flow direction during the regeneration reaction is opposite to that in the adsorption reaction, the calorific value due to the heat of the regeneration reaction is smaller in both the absorbent length direction and the cross section than in the comparative example in which the same direction is used, and the heat resistance of the adsorbent is reduced. From the standpoint of sex, since it is hard to deactivate, it has the advantage of withstanding long-term use.

[Brief description of drawings]

1 and 2 are explanatory views of an embodiment of the apparatus of the present invention, FIG. 1 shows the entire flow when the apparatus of the present invention is incorporated into a coal gasifier, and FIG. 2 shows an adsorbent. 1 shows the structure of a reactor filled with. FIG. 3 is a diagram showing the results of measuring the temperature distribution inside the reactors of Examples of the present invention and Comparative Examples.

Claims (1)

[Claims] 1. A tubular structure in a device in which a sulfur compound contained in a high-temperature reducing gas is adsorbed and removed by an adsorbent containing a metal oxide as a main component, and the adsorbent is regenerated for repeated use. Solid gas characterized by arranging a large number of adsorbents composed of a body so that the adsorption surface is parallel to the gas flow, and enabling the gas flow directions during adsorption and regeneration to be opposite. Catalytic reactor.