JP2647596B2 - High-temperature reducing gas purification equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for purifying a high-temperature reducing gas, and more particularly, to a method for reducing sulfur compounds such as hydrogen sulfide and carbonyl sulfide contained in a high-temperature reducing gas such as a product gas of a coal gasification process. And a device for removing the same.

[0002]

2. Description of the Related Art In recent years, diversification of fuels (or raw materials) has been called out due to the depletion of petroleum resources and rising prices, and coal and heavy oils (tar sand oil, oil shale oil, Daqing crude oil, Maya crude oil or decompression residue) have been developed. (Eg oil) is being developed. However, this gasification product gas contains sulfur compounds such as hydrogen sulfide (H ₂ S) and carbonyl sulfide (COS) of several hundred to several thousand ppm, depending on the raw material coal and heavy oil, and is used for pollution prevention or It must be removed to prevent corrosion of downstream equipment. As the removal method, the dry method is thermoeconomically advantageous and the process configuration is simple, so that a method of absorbing and removing an absorbent mainly composed of a metal oxide as a sulfide at a high temperature has become common. I have.

As an absorbent, Fe, Zn, Mn, Cu,
Metal oxides such as Mo and W are used, and 250 to 500
It reacts with hydrogen sulfide (H ₂ S) and carbonyl sulfide (COS) at ℃. When the case of H ₂ S and Fe ₃ O ₄ is explained as an example, the absorption reaction is as shown in equations (1) to (2). It is said to proceed to. _{Fe 3 O 4 + H 2 +} 3H 2 S → 3FeS + 4H 2 O ··· (1) Fe 3 O 4 + CO + 3H 2 S → 3FeS + 3H 2 O + CO 2 ··· (2)

Then, the absorbent after the absorption reaction is regenerated with an oxygen-containing gas into a metal oxide Fe ₂ O ₃ as shown in equation (3), and is recovered and removed as a sulfur compound SO ₂ gas in a high-temperature reducing gas. You. 4FeS + 7O ₂ → 2Fe ₂ O ₃ + 4SO ₂ (3)

Further, when a reducing gas containing H ₂ S or CO is passed after the regeneration reaction, the absorbent becomes the original Fe ₃ O ₄ as shown in equations (4) to (5). , Regeneration reaction,
The metal oxide (Fe ₃ O ₄ ) is effectively used by repeating the reduction reaction. 3 Fe ₂ O ₃ + H ₂ → 2Fe ₃ O ₄ + H ₂ O (4) 3 Fe ₂ O ₃ + CO → 2Fe ₃ O ₄ + CO ₂ (5)

[0006] As the absorbent used in this process, those obtained by forming the above-mentioned metal oxide alone or on a heat-resistant porous material into a columnar or honeycomb shape are usually used.

An example of a conventional device will be specifically described with reference to FIGS. 2 is a process flow diagram of the conventional device, FIG. 3 is a valve arrangement diagram for switching the reaction tower of the conventional device of FIG. 2, and FIG. 4 is a time chart chart of an absorption, regeneration, and reduction cycle of the conventional device of FIG. 5 is a chart showing opening and closing of a valve for switching the reaction tower in the conventional apparatus of FIG.

In FIG. 2, the unpurified gasification product gas flows into the reaction tower 1 via pipes 10 and 44, and the absorbent (Fe ₃ O ₄ ) 100 filled in the reaction tower 1 and (1) ~ (2)
The sulfide (H ₂ S, COS) contained in the gasification product gas is absorbed and removed by the reaction of the formula (this reaction process is referred to as an absorption process), and the gasification product gas purified via the pipes 45 and 11 is removed. Is sent as fuel to a gas turbine of a subsequent device (not shown).

A part of the purified gasification product gas branched from the pipe 45 flows into the reaction tower 2 via the pipe 13 and is reduced with the reducing gas (H ₂ , CO) contained in the gasification product gas. The absorbent (Fe ₂ O ₃ ) 100 changes to Fe ₃ O ₄ by the reaction of the formulas (4) and (5). (This reaction step is called a reduction step.) The flow rate of the gas flowing into the reaction tower 2 is controlled by the flow rate detection controller 30.
And the valve 31 is controlled to be constant by a predetermined amount.

The oxygen-containing gas flows into the reaction tower 3 via the pipe 15, and causes a reaction of the formula (3) with FeS adsorbed on the absorbent. As a result, the SO ₂ gas is generated, and the absorbent 100 returns to the metal oxide (Fe ₂ O ₃ ) and is regenerated. (This reaction step is called a regeneration step.)

If the absorption step is continued for a certain period of time in the reaction column 1, the total amount of Fe ₃ O _{4 as the} absorbent is changed to FeS, and the reaction of the formulas (1) and (2) cannot be caused any more. Then, the sulfide (H ₂ S, COS) flows out from the outlet of the reaction tower 1. Therefore, it is considered that the reaction tower 1 is changed from the absorption step to the regeneration step, the reaction tower 2 is changed from the reduction step to the absorption step, and the reaction tower 3 is changed from the regeneration step to the reduction step.

FIG. 4 shows a time chart of each step. In FIG. 4, the duration of the absorption step is 4 hours.

The operation for changing each step is performed by opening and closing valves 61 to 75 shown in FIG. Valves 61 to 61 shown in FIG.
The open / closed state of 75 (white: open; black: closed) indicates a time chart of 0 to 4 hours or 12 to 16 hours in the time chart of FIG. In FIG. 5, regarding the reaction tower 1, since the valves 61 and 68 are open and the valves 62, 67 and 69 are closed, the unpurified gasification product gas flows through the pipes 10, 46 and 44 to the reaction tower 1. 1 and flows out to the subsequent equipment via the pipes 53 and 11, and thus corresponds to the absorption step shown in FIG. Further, regarding the reaction tower 2, since the valves 64 and 70 are open and the valves 63, 71 and 72 are closed, the purified gasification product gas is supplied to the reaction tower 2 via the pipes 78, 55 and 13. Since it enters and flows into the pipe 16 via the pipes 12 and 49, it corresponds to the reduction step shown in FIG. Also,
Regarding the reaction tower 3, since the valves 66 and 75 are open and the valves 65, 73 and 74 are closed, the oxygen-containing gas enters the reaction tower 3 via the pipes 25, 60 and 15, and the pipes 14 and Since the gas flows into the pipe 16 via 51, FIG.
Corresponds to the regeneration step shown in FIG.

Therefore, the open / closed state of the valve in FIG. 3 corresponds to FIG.

FIG. 5 shows the open / closed state of the valves 61 to 75 in the time zone shown in the time chart of FIG. As shown in FIG. 5, by operating the valves 61 to 75 every 4 hours, each of the reaction towers 1, 2, and 3 sequentially changes in the order of the deflow step, the regeneration step, the reduction step, and the deflow step. be able to.

Next, referring to FIG. 2, the S
A process of recovering O ₂ gas as single sulfur will be described. The SO ₂ gas generated in the regeneration step of the reaction tower 3 enters the heat exchanger 4 via the pipes 14 and 16. The gas after the reaction in the reduction step of the reaction tower 2 joins the pipe 16 via the pipe 12. In the regeneration step, a high-temperature gas is generated by the heat of the oxidation reaction, but is cooled by the heat exchanger 4 and enters the cooler 5 via the pipe 17. It is further cooled by the cooler 5 and the piping 18
And enters the reduction reactor 6. Part of the unpurified gasification product gas containing H ₂ and CO as main components joins the pipe 17 via the pipe 27. A part of the gasification product gas is constantly controlled at a constant flow rate by a flow controller 32 and a valve 33. The reduction reactor 6 is filled with the catalyst 101, and the reduction reactions of the equations (6) and (7) occur to generate single sulfur Sx. SO ₂ + 2H ₂ → 1 / xSx + 2H ₂ O (x = 2 to 8) (6) SO ₂ + 2CO → 1 / xSx + 2CO ₂ (x = 2 to 8) (7)

The temperature in the reduction reactor 6 is controlled by the temperature detector 34 and the valve 35 for controlling the flow rate of the refrigerant 28 to the cooler 5 so that the reaction of the formulas (6) and (7) can easily proceed (for example, 250 ° C.). Is controlled. The gas containing the vapor of the elemental sulfur flowing out of the reduction reactor 6 enters the cooler 7 via the pipe 19, and is further cooled therein, enters the sulfur condenser 8 via the pipe 20, and condenses into liquid elemental sulfur. . The temperature inside the sulfur condenser 8 is controlled by a temperature detection controller 36 and a valve 37 for controlling the flow rate of the refrigerant 29 of the cooler 7 so that the temperature is lower than the condensation temperature of sulfur.

The sulfur liquefied by the sulfur condenser 8 is taken out of the system through a pipe 77. On the other hand, the inert gas (main component N ₂ ) from which sulfur has been removed by the sulfur condenser 8 enters the circulation blower 9 via the pipe 21. Piping 2
The circulating flow rate is controlled to be constant by a valve 39 and a flow rate detection controller 38 installed at 1. The heat enters the heat exchanger 4 via the pipes 22 and 24 from the circulation blower 9 and is heated. Air or oxygen is mixed into the pipe 24 through the pipe 23, and the oxygen concentration in the pipe 24 is controlled by the oxygen concentration detection controller 40.
And the valve 41 is controlled to a predetermined value.

The oxygen-containing gas is heated by the heat exchanger 4 and enters the reactor 3 via the pipes 25 and 15. The gas partially branched from the pipe 22 is supplied to the pipe 1 via the pipe 26.
Merge to 0. A valve 43 is installed in the pipe 26, and is controlled by the pressure detection controller 42 and the valve 43 so that the pressure of the circulation blower 9 becomes constant.

[0020]

In a reaction tower 3 corresponding to the regeneration step shown in FIG. 2, iron sulfide FeS is oxidized by an oxygen-containing gas as shown by equation (3), and a metal oxide Fe ₂ O ₃
And SO ₂ gas are generated. However, F in the reaction tower 3
When the total amount of eS is oxidized, the substance that reacts with oxygen disappears, and the oxygen flows out of the outlet pipe 14 of the reaction tower 3 without reacting. The gas flowing out of the reaction tower 3 is SO ₂
It flows into a reduction reactor 6 for reducing gas. This reduction reactor 6 is filled with the catalyst 101, and if unreacted oxygen flows into the reduction reactor 6, the catalyst 101 is oxidized and deteriorated, so that it does not function as a catalyst. is there.

The present invention has been made in view of the above-mentioned state of the art, and has as its object to provide a high-temperature reducing gas purifying apparatus which solves the problems in the prior art and prevents deterioration of a catalyst in a reduction reactor.

[0022]

According to the present invention, in removing a sulfur compound such as hydrogen sulfide and carbonyl sulfide contained in a high-temperature reducing gas with an absorbent, the sulfur compound is absorbed and removed with the absorbent. Absorption step, a regeneration step of regenerating the absorbent that has absorbed the sulfur compound with an oxygen-containing gas,
And a reducing step of reducing the regenerated the absorbent in the high temperature reducing gas, at least filled with absorbent capable of sequential changes by the opening and closing <br/> a plurality of valves installed in a doorway 3
In a high-temperature reducing gas purifying apparatus consisting of reaction towers, the reaction towers connected to each reaction tower and in the regeneration step
O ₂ concentration meter installed in the outlet pipe into which the outlet gas flows , a function generator that receives the detection signal of the O ₂ concentration meter as an input , connected to each reaction column, and oxygen is supplied to the reaction column in the regeneration step.
An O ₂ concentration detection controller installed in an inlet pipe for supplying a contained gas, a minimum value selector to which an output signal of the O ₂ concentration detection controller and an output signal of the function generator are input, and the regeneration
A valve installed on an air or oxygen supply pipe for mixing air or oxygen into an inlet pipe for supplying an oxygen-containing gas to a reaction tower in a process , and operated by an output signal of the minimum value selector. And a high-temperature reducing gas purifying apparatus.

The present invention prevents oxygen from flowing into the SO ₂ gas reduction reactor and deteriorating the catalyst.
That is, when oxygen is detected at the inlet of the reduction reactor (outlet of the regeneration step), the valve of the air or oxygen supply pipe is fully closed to prevent excess oxygen from flowing into the system, This prevents deterioration of the catalyst in the vessel.

[0024]

An embodiment of the present invention will be described with reference to FIG.
In the conventional device of the apparatus of FIG. 1 FIG. 2, the function generator 8 which receives the detection signal of the piping 16 O ₂ concentration meter 79 and the O ₂ concentration meter 79 corresponding to the outlet of the reaction column 3 in the regeneration step
0, and installed in a pipe 24 corresponding to the inlet of the reaction tower 3.
The minimum value selector 81 for selecting the smaller of vignetting in which the O ₂ concentration detected adjusting meter 40 output signal and the output signal of the <br/> function generator 80 is provided, the output signal of the outermost minimum value selector 81 By operating the valve 41 of the pipe 23 to prevent excess oxygen from flowing into the system, there is no difference in other device configurations. Therefore, for the other device configurations, the same members as those in FIG.

FIG. 6 shows an example of the function generator 80 shown in FIG.
It is assumed that the function shown in is set.

When the detected value of the O ₂ concentration in the outlet pipe 16 of the regeneration step detects a value of 0.2 vol% or more, the output signal of the function generator 80 becomes zero (corresponding to valve fully closed) from FIG. The output signal of the selector 81 is naturally zero. Therefore, the valve 41 is fully closed, supply of air or oxygen stops, and oxygen flowing out from the outlet of the regeneration step stops. Therefore, deterioration of the catalyst in the reduction reactor 6 is minimized. In FIG. 6, the O ₂ concentration that is fully closed is set to 0.2 vol% in consideration of a detection error.
Basically, a smaller value may be used.

Although the embodiment of the present invention has been described, it is sufficient that the oxygen supply source is shut off when the O ₂ concentration is detected at the outlet of the regeneration step.

[0028]

According to the present invention, oxygen is prevented from being mixed into SO ₂ collected from the high-temperature reducing gas purifier, and the catalyst in the reduction reactor for reducing the high-temperature reducing gas to sulfur is reduced. An apparatus for purifying a high-temperature reducing gas capable of preventing deterioration is provided.

[Brief description of the drawings]

FIG. 1 is a process flow diagram of a purification device according to an embodiment of the present invention.

FIG. 2 is a process flow diagram of a conventional apparatus.

FIG. 3 is a valve arrangement diagram for switching a reaction tower of a conventional apparatus.

FIG. 4 is a time chart chart of an absorption / regeneration / reduction cycle of a conventional apparatus.

FIG. 5 is a chart showing opening and closing of a valve for switching a reaction tower in a conventional apparatus.

FIG. 6 is a diagram showing a specific example of a function set in a function generator according to the present invention, which is one embodiment shown in FIG. 1;

Claims (1)

(57) [Claims] 1. A hydrogen sulfide contained in a high-temperature reducing gas,
In removing a sulfur compound such as carbonyl sulfide with an absorbent, an absorption step of absorbing and removing the sulfur compound with the absorbent, and a regeneration step of regenerating the absorbent having absorbed the sulfur compound with an oxygen-containing gas. and a reduction step of reducing the regenerated the absorbent in the high temperature reducing gas, the absorbent can sequential changed by the opening and closing of a plurality of valves installed in the doorway from the reaction column of at least 3 column packed Connected to each reaction tower in the configured high-temperature reducing gas purification device
Is, placed the O ₂ concentration meter <br/> outlet pipe exit gas from the reaction tower in the regeneration step flows, function generator which receives the detection signal of the O ₂ concentration meter, connected to each reaction column And re
O ₂ concentration detection controller installed in an inlet pipe for supplying an oxygen-containing gas to a reaction tower in a raw process, a minimum value to which an output signal of the O ₂ concentration detection controller and an output signal of the function generator are input. Selector, containing oxygen to the reaction tower in the regeneration step
A high-temperature reducing gas, comprising: a valve installed on an air or oxygen supply pipe for mixing air or oxygen into an inlet pipe for supplying gas , and operated by an output signal of the minimum value selector. Purification equipment.