JPH066708B2 - Coal gasification method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a coal gasification method, and more particularly to a jet bed coal gasification method.

(Prior Art) Generally, a coal gasifier that gasifies coal with a guide agent such as air, oxygen, or oxygen-enriched air to generate a combustible gas, has various gasification methods depending on the use of the generated gas. There are, for example, a spouted bed system, a fluidized bed system, and a fixed bed system according to the type. The spouted bed method is a method in which pulverized coal is gasified by spraying it with a gasifying agent from a nozzle.

As is well known, these gasifiers are used as one process for so-called combined power generation in which chemical raw materials are manufactured or combined with a gas turbine or the like.

FIG. 1 is a diagram showing a schematic configuration of a jet-bed type coal gasifier, in which reference numeral 1 is a jet-bed type coal gasification furnace. This jet bed coal gasification furnace (hereinafter referred to as gasification furnace) 1 utilizes the high temperatures of the combustor section 2 and the combustor section 2 that form a high temperature region required for gasification reaction and slag melting, and produces pulverized coal. It is composed of a reactor part 3 for gasifying. An ejection nozzle 4 for ejecting pulverized coal with a gasifying agent such as air is provided at the bottom of the reactor section 3, and 5 is the pulverized coal and gasifying agent supply line. The air ratio of the supply line 5 (= the supply air amount / theoretical air amount for combustion) is usually adjusted to 0.6 to 0.7. Further, on the upper part of the reactor section 3, a produced gas take-out line 6 for taking out produced gas, a cyclone 11 for collecting unreacted char and a char recovery line 7 are provided. The other end of the char recovery line 7 is connected to the combustor section 2, and the unreacted char recovered from the reactor section 3 is supplied to the combustor section 2 as auxiliary fuel. The main fuel of the combustor unit 2 is supplied from the fuel supply line 8.

In the combustor unit 2, pulverized coal is burned at an air ratio of 0.6 to 1.2 to form a high temperature region (1500 to 1700 ° C.) necessary for gasification reaction (endothermic reaction) and slag melting. In the reactor section 3, the pulverized coal ejected from the ejection nozzle 4 is gasified by the combustion heat of the combustor section 2 to obtain a produced gas mainly containing hydrogen, carbon monoxide, methane and the like. This product gas is at the upper part of the reactor part 3 (the temperature of this part is generally 500
˜1100 ° C.) and taken out from the product gas take-out line 6. Also, the reactor part 3 together with the generated gas
The char of the unreacted ascending to the top of the char is the char recovery line
Is supplied to the combustor unit 2 from the combustion chamber and is burned together with the main fuel (pulverized coal). The pulverized coal burned in the combustor unit 2 and the ash content in the char become molten slag, which is discharged from the molten slag discharge port 9 and dropped into water for recovery.

1, 10 and 10A are air supply lines to the combustor unit 2.

By the way, in such a coal gasifier, the produced gas contains nitrogen compounds such as NH ₃ and HCN in addition to the main components of CO and H ₂ , but these are the subsequent processes of the combined power generation system, that is, the desulfurization device and It has a great impact on the gas turbine. Especially dry type clean-up system (dry dust removal, dry desulfurization, etc.
If operated at about 400 ° C.), these are hardly removed and are finally burned in a gas turbine to produce NO _x , which is an air pollutant. Also, when a wet clean-up system is adopted, it has adverse effects such as accelerated deterioration of the absorbent. Therefore, it is desirable to reduce NH ₃ and HCN in the produced gas in the gasification furnace as much as possible.

(Problems to be Solved by the Invention) The present invention relates to N in the produced gas in a spouted bed type coal gasification furnace.
It is intended to provide a coal gasification method capable of reducing H ₃ and HCN.

(Means for Solving Problems) The present inventors diligently studied the production of NH ₃ and HCN in the coal gasification furnace, and (1) most of NH ₃ and HCN in the produced gas were nitrogen in the coal. It was found that the amount of NH ₃ and HCN produced was small, and the balance was converted to harmless N ₂ , such as in high temperature atmospheres and high air ratios. The invention has been completed.

The present invention relates to a two-stage jet flow composed of a combustor section that forms a high temperature region required for gasification reaction and slag melting, and a reactor section that uses the high temperature of this combustor section to gasify pulverized coal with a gasifying agent. When two or more types of coal are gasified by a bed-type coal gasifier, by supplying more coal with a high nitrogen content to the combustor section, the NH
₃ and a method for gasifying coal, which is characterized by reducing HCN concentration.

That is, since the combustor is maintained at a high temperature and a high air ratio as described above, the conversion rate of nitrogen content in coal to NH ₃ and HCN is low. On the other hand, is supplied with the same coal to the reactor, wherein the low air ratio, and since it is compared to 300 to 400 ° C. Low temperature combustor section, a number of NH _3, HCN
Will be included in the product gas without being converted to N ₂ and will escape to the wake.

It goes without saying that there is a limit due to the balance of the entire gasification furnace or the supply state of various types of coal, but coal with a high nitrogen content should be treated with a combustor as much as possible.
This is a desirable translation for reducing H ₃ and HCN.

Example A basic experimental apparatus having the same configuration as that in FIG. 1 (coal throughput 1
The concentration of NH ₃ and HCN in the produced gas was measured by a test using 100 kg / H), and the results shown in Table 1 were obtained.

As shown in the table, it is understood that the method of the present invention can significantly reduce the amounts of NH ₃ and HCN in the produced gas.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a jet bed coal gasifier. 1 ... Gasification furnace, 2 ... Combustor section, 3 ... Reactor section, 5 ... Pulverized coal and gasifying agent supply line, 6 ... Generated gas extraction line, 7 ... Char recovery line, 10,1
0A: Air supply line, 11: Cyclone for collecting char.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kazuhiro Takeda 1-1, Atsunoura-machi, Nagasaki-shi, Nagasaki Mitsubishi Heavy Industries, Ltd. Nagasaki Research Institute (72) Inventor Shigeo Suhara 2-4, Kiyogaoka, Tama-shi, Tokyo 5 (72) Inventor Jun Inumaru 1-16-3-201 Iwatokita, Komae-shi, Tokyo

Claims (1)

[Claims] 1. A two-stage structure comprising a combustor section for forming a high temperature region required for gasification reaction and slag melting, and a reactor section for gasifying pulverized coal with a gasifying agent by utilizing the high temperature of the combustor section. When two or more types of coal are gasified by the jet bed coal gasifier, by supplying more coal with a high nitrogen content to the combustor section,
A method for gasifying coal, which comprises reducing the concentrations of NH ₃ and HCN.