JPH03292398A - Method of dry desulfurization in coal gasifying plant - Google Patents

Abstract

PURPOSE:To reduce the cost in a coal gasifying plant by supplying coal char separated from coal gasification gas to a reducing tower as a reducting agent. CONSTITUTION:Coal from a line 2, air from a line 3, and steam from a line 4 are fed into a coal gasifier 1, where the coal is partially oxidized and reduced to give coal gasification gas. This gas is introduced through a line 5 into a cyclone 6 to separate coal char therefrom and sent to a dedusting unit, where the remaining coal char is collected as dust. It is then introduced into the absorption tower 9 of dry desulfurization equipment 8 to effect desulfurization. The desulfurizing agent after being used for disulfurization in the tower 9 is sent through a line 11 to a regeneration tower 10, where it is regenerated and then returned through a line 12 to the tower 9. Separately, SO2 gas generated in the tower 10 is fed through a line 13 into a reducing tower 14. The coal char caught by the cyclone 6 is discharged into a line 17, a part of which is returned to the gasifier 1. The remainder thereof and the coal char collected by the unit 7 are supplied as a reducing agent to the tower 14 through a line 16.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dry desulfurization method in a coal gasification plant, and particularly to a method for reducing sulfur dioxide gas with coal char separated from coal gasification gas from a coal gasification furnace. The present invention relates to a dry desulfurization method in a coal gasification plant.

[Prior Art] Generally, in a coal gasification plant, coal is gasified in a high-temperature, high-pressure gasification furnace to produce coal gasification gas, and unburned coal content (coal char) contained in the generated coal gasification gas is )
is separated and removed using a cyclone or the like, and the sulfur content (mainly hydrogen sulfide) is absorbed and removed using a dry desulfurization device to obtain purified coal gasified gas. Coal char captured by a cyclone or the like is returned to the gasifier.

The dry desulfurization apparatus described above desulfurizes coal gasified gas by contacting it with a desulfurization agent in an absorption tower, and the desulfurization agent after the desulfurization treatment is regenerated in a regeneration tower.

In the regeneration tower, sulfur dioxide gas is generated when the desulfurization agent is regenerated, and in order to recover this sulfur dioxide gas as elemental sulfur, the sulfur dioxide gas is introduced into the reduction tower. Therefore, coal, such as anthracite, is brought into contact with a moving layer formed by a reducing agent at high temperature.
Reduces sulfur dioxide gas.

[Problem to be solved by the invention] However, in order to reduce sulfur dioxide gas, a reducing agent such as anthracite is required. Since it does not contribute to the purification of gasified gas, there is a problem in that the cost of the coal gasification plant increases.

Therefore, the present invention was made to solve the above problems, and an object of the present invention is to provide a dry desulfurization method for a coal gasification plant that makes it possible to reduce the cost of the coal gasification plant.

[Means for Solving the Problems] In order to achieve the above object, the present invention desulfurizes coal gasified gas from a coal gasification furnace with a desulfurization agent, and removes sulfurous acid generated when the desulfurization agent is regenerated. In a dry desulfurization method in a coal gasification plant in which gas is led to a reduction tower and reduced, coal char is separated from the coal gasification gas and is supplied to the reduction tower as a reducing agent.

[Function] According to the above configuration, coal char is separated from coal gasification gas, and this coal char is supplied to the reduction tower together with a reducing agent, so that sulfur dioxide gas is brought into contact with the coal char and reduced in the reduction tower. be done. This eliminates the need for a reducing agent such as anthracite, which is used only to reduce sulfur dioxide gas, and thus reduces the cost of the coal ossification plant.

[Embodiment J] Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a high-temperature, high-pressure coal gasifier, to which a coal line 2 for supplying coal, an air line 4, and a steam line 4 are connected.

A gasification line 5 for the generated coal ossification gas is connected to the coal gasification furnace 1, and a cyclone 6 for capturing unburned coal (coal char) in the gas, coal char, etc. are connected to the gasification line 5. A desulfurization facility 7 for collecting dust and an absorption tower 9 of a dry desulfurization device 8 are installed in sequence.

The absorption tower 9 absorbs and removes the sulfur content (mainly hydrogen sulfide) in the coal gasification gas using a desulfurization agent such as iron oxide, and is used to transport the desulfurization agent after the desulfurization treatment to the regeneration tower 10. A line 11 is connected thereto, and a return line 12 for the desulfurizing agent regenerated in the regeneration tower 10 is also connected.

The regeneration tower 10 regenerates the desulfurization agent using air or the like.
A regeneration exhaust gas line 13 for regeneration exhaust gas containing sulfur dioxide gas generated when regenerating the desulfurization agent is connected. This regeneration exhaust gas line 13 is connected to the reduction tower 14.

An air introduction line 15 for introducing air is connected to the reduction tower 14, and a reducing agent line 1 is connected to the upper part.
6 are connected. This reducing agent line 16 is connected to a coal char supply line 17 from the cyclone 6 and a second coal char supply line 18 from the dust removal equipment 7, and some of the char from the cyclone 6 and the dust removal equipment 7 are connected to the reducing agent line 16. Char is supplied to the reduction tower 14 as a reducing agent.

The reducing tower 14 is configured to gradually move the coal char as a reducing agent from the reducing agent line 16 downward continuously or intermittently to form a moving bed of coal char, and the moving bed and sulfur dioxide gas The sulfur dioxide gas is reduced to sulfur gas upon contact at high temperatures. The sulfur gas is recovered as elemental sulfur using a single sulfur condenser. Further, a discharge line 20 is connected to the lower part of the reducing tower 14 for discharging ash and unburned matter generated in the tower 14, and the unburned matter in the line 20 is transferred to the reducing agent line 20. A circulation line 21 supplying the 16 is also connected.

Furthermore, a coal supply line 22 is connected to the upper part of the reduction tower 14 for supplying coal such as anthracite to form a moving bed when a moving bed cannot be formed using coal char, such as during startup.

In the above process, coal is first supplied into the coal gasifier 1 from the coal line 2, air from the air line 3, and steam from the steam line 4, and the coal is partially oxidized and reduced to produce coal gas. It becomes a chemical gas. This coal gasification gas flows into the gasification line 5, and the cyclone 6
Most of the unburned coal (coal char) in the gas is captured, and the remaining coal char is collected in the desulfurization equipment 7 and then enters the absorption tower 9 of the dry desulfurization equipment 8.

The coal gasification gas is desulfurized and purified by contacting with a desulfurizing agent such as iron oxide in the absorption tower 9, and then used as fuel for a gas turbine or the like.

The desulfurizing agent that desulfurizes the gas in the absorption tower is transferred to the transfer line 1.
1 to the regeneration tower 10, where it is regenerated with air or the like, and then returned to the absorption tower 9 through the return line 12. Regeneration exhaust gas containing sulfur dioxide gas generated in the regeneration tower 10 enters the reduction tower 14 via the regeneration exhaust gas line 13.

The coal char captured by the cyclone 6 is discharged to the coal char supply line 17 , a part of which is returned to the coal gasifier 1 , and the remainder is supplied to the reducing agent line 16 . Further, the coal char collected in the desulfurization equipment 7 is discharged to the second coal char supply line 18 and is then supplied into the reduction tower 14 together with the coal char from the cyclone 6 via the reducing agent line 16. . Then, within the tower 14, the coal char gradually moves downward continuously or intermittently to form a moving layer. The regenerated exhaust gas is brought into contact with this moving bed orthogonally at high temperature and is caused to cross in the horizontal direction. This reduces sulfur dioxide gas to sulfur gas (C+SO2→5
-LCO□). This sulfur gas is sulfur capacitor 1
9, it is condensed and recovered as elemental sulfur.

As mentioned above, in the coal gasifier 1, coal is partially oxidized and reduced to generate coal gasified gas, so the generated gas contains a large amount of coal char (approximately 1% of the amount of coal to the gasifier).
0-40%). For this reason, coal char is separated from coal gasification gas, and this coal char is sent to the reduction tower 14.
Even if the coal char is supplied as a reducing agent, a moving layer of coal char can be sufficiently formed, and even if the sulfur dioxide gas is reduced with the coal char, it is not reduced as much as when it is reduced with conventional anthracite. Performance will not deteriorate.

Therefore, by separating coal char from coal gasification gas and using it as a reducing agent in the reduction tower 14, sulfur dioxide gas can be reduced with the gasified coal in the coal gasification plant. This eliminates the need for anthracite, etc., which is used exclusively for coal gasification, and reduces the cost of coal gasification plants.

[Effects of the Invention] In summary, according to the present invention, coal char is separated from coal gasified gas and supplied as a reducing agent to a reduction tower,
Since sulfur dioxide gas is reduced with coal char, it has the excellent effect of reducing the cost of coal gasification plants.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an example of a device for concretely implementing the present invention. In the figure, 1 is a coal gasifier, 6 is a cyclone, 8 is a dry desulfurization device, 14 is a reduction tower, and 16 is a reducing agent line.

Claims (1)

[Claims] 1. In a dry desulfurization method in a coal gasification plant, in which coal gasification gas from a coal gasification furnace is desulfurized with a desulfurization agent, and sulfur dioxide gas generated when regenerating the desulfurization agent is led to a reduction tower and reduced. A method for dry desulfurization in a coal gasification plant, characterized in that coal char is separated from the coal gasification gas and supplied as a reducing agent to the reduction tower.