JPH0472878B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coal gasification process, and more particularly to an spouted bed type coal gasification process.

In general, coal gasifiers that generate combustible gas by gasifying coal with a gasifying agent such as air or oxygen have various gasification methods depending on the use of the produced gas. , fluidized bed type, fixed bed type, etc. The spouted bed type is a method in which pulverized coal is jetted out from a nozzle together with a gasifying agent to gasify it.

FIG. 1 is an explanatory diagram of a conventional spouted bed type coal gasification process, and in FIG. 1, 1 is a spouted bed type coal gasifier. This entrained bed coal gasifier (hereinafter referred to as gasifier) 1 is a combustor section 2 that forms a high temperature region necessary for gasification reaction, and a reactor that gasifies pulverized coal using the high temperature of the combustor section 2. It consists of Section 3. The combustor section 2 is provided with an ejection nozzle 4 for ejecting pulverized coal together with a gasifying agent such as air, and 5 and 6 are supply lines for the pulverized coal and the gasifying agent, respectively. In addition,
The air ratio (stoichiometric ratio of air and pulverized coal) in the combustor 2 is normally adjusted to 0.6 to 0.7. Pulverized coal and gasification agent are also supplied from the nozzle 7 at the bottom of the reactor, and the overall air ratio (stoichiometric ratio of air supplied to the combustor section and reactor section and pulverized coal) is adjusted to 0.4 to 0.6. . 8 and 9 are gasifying agent and pulverized coal supply lines, respectively. Further, in the upper part of the reactor 3, there are provided a produced gas take-off line 10 for taking out produced gas, a cyclone 11 for collecting unreacted chir, and a chir collection line 12. The other end of this chear recovery line 12 is connected to the combustor section 2, and the recovered unreacted chard is supplied to the combustor section 2 along with a small amount of gasifying agent via the line 13 as auxiliary fuel. On the other hand, the generated gas is purified through a dust collector 101 and a wet desulfurization device 102, and is supplied as purified gas to a desired purpose through a line 103.

With the gasifier configured in this way, the combustor section 2 burns the pulverized coal to form a high temperature region necessary for the gasification reaction (endothermic reaction), and the reactor section 3 burns the pulverized coal ejected from the ejection nozzle 7. is gasified with a gasifying agent such as air using the combustion heat (1500 to 1700°C) of the combustor section 2 to obtain a generated gas mainly containing hydrogen, carbon monoxide, methane, etc. The pulverized coal burned in the combustor section 2 and the ash in the char become molten slag and are discharged from the molten slag discharge port 14, dropped into water, and recovered.

The above is a brief description of one type of entrained bed gasifier, but at present there are still research issues to be solved regarding the gasifier itself, and one of them is the smooth discharge of slag from the bottom of the furnace. be. In fact, for coal such as Australian coal, which has a high melting point and low viscosity and an ash component, special measures are required to discharge the slag, such as maintaining the inside of the combustor at a very high temperature.

The inventors of the present invention have conducted intensive research on methods for smoothly discharging slag, and have found that the used waste desulfurization agent from the desulfurization equipment, which is one of the cleanup systems installed after the gasifier, reduces the slag viscosity. It was discovered that this has the effect of facilitating slag discharge, and based on this knowledge, the present invention was developed. Also,
The present invention has the advantage that it is not necessary to dispose of the used desulfurizing agent containing sulfur, which is difficult to dispose of, and is an extremely useful invention industrially.

That is, the present invention provides a slug-tap coal gasification process in which coal, which is a raw material, is gasified with a smaller amount of air and/or oxygen than its stoichiometric amount to obtain a gas whose main components are CO and _H2 . In this paper, we propose a spouted bed type coal gasification process characterized by charging spent waste of desulfurization agent for removing sulfur content from crude gas into the high-temperature section of a gasifier.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is an explanatory diagram of one embodiment of the present invention. In FIG. 2, the same reference numerals as in FIG. 1 indicate parts having the same functions as in FIG. In FIG. 2, line 15 is the crude gasification product gas, and the main components are CO, H ₂ , CH ₄ ,
In addition to CO ₂ , H ₂ O, and N ₂ , it also contains trace components such as dust H ₂ S and NH ₃ . These trace components need to be reduced to a fairly low concentration no matter what purpose the produced gas is used for, for example, as gas turbine fuel for combined power generation, city gas fuel, or chemical raw material. 16 is a precision dust removing device, and 17 is a line for extracting the collected dust. 18 and 19 are
This is a dry desulfurization equipment for H ₂ S removal, and although the figure shows an example of a two-column fluidized bed continuous regeneration system, it is not limited to this, and of course other types such as fixed An intermittent switching method is also applicable. 18 is a H ₂ S absorption device, and 19 is a regeneration device whose purpose is to release the absorbed H ₂ S using a regeneration gas (for example, air) to restore the desulfurizing agent activity. Further, 20 is a supply line for regeneration gas, and 21 is a flow path for gas containing a high concentration of S to reach the S recovery device.

The purified gas thus purified through the processes of dust removal and desulfurization is supplied to the above-mentioned required purpose via the flow path 20.

Here, desulfurization agents generally include iron oxide (Fe ₂ O ₃ ), alkali carbonates (CaCO ₃ , MgCO ₃ ),
Zinc oxide (ZnO), copper oxide (CuO), etc. are used, but some of these lose their activity over time and must be discarded and discharged from the system. 22 is the waste discharge line, but this used desulfurization agent contains S content and, depending on the operating conditions, trace amounts of Cl content, CN content, etc., and is difficult to easily return to the environment for pollution prevention reasons. .

In the present invention, this is supplied to the combustor section 2 and subjected to high temperature treatment in the combustor together with pulverized coal or coal. This reduces the slag viscosity and
There is also no need to process desulfurization waste. The reduction in slag viscosity enables smooth continuous operation of the gasifier, and since it is no longer necessary to maintain the combustor at a very high temperature, the amount of air required in the combustor is reduced, resulting in the calorific value of the produced gas. This is extremely desirable in terms of the process, as it leads to an increase in the overall efficiency. Of course, Fe, Ca, etc. in the waste desulfurization agent are captured in the slag. In addition, S minute, Cl minute,
Although CN components and the like are released into the generated gas, these are extremely small amounts compared to the amount of each component in the main stream and pose no problem.

As explained in detail above, the process of the present invention improves the slag discharge characteristics, which is one of the biggest problems of entrained bed gasifiers, and makes the slag discharge smoother. The present invention provides an industrially extremely useful process, which has the unique effect of eliminating the need for treatment.

Hereinafter, the effects of the present invention will be explained in detail using Examples.

Example 1 First, a small fixed bed desulfurization equipment (processing gas amount 15N
/min) and conducted a desulfurization test. Powdered iron oxide (Fe ₂ O ₃ ) was used as the desulfurizing agent. about
After 250 hours of continuous testing, the desulfurization performance was the initial 80
%, this was fed into an atmospheric pressure spouted bed gasifier having a processing capacity of 100 kg/H together with pulverized coal (Australian steam coal) at a rate of 2 kg/H for about 1 hour.

As a result, since the combustor is maintained at a high temperature (approximately 1700℃) before it is turned on, the overall air ratio is
An amount of air equivalent to 0.56 was required as a gasifying agent, but due to the effect of reducing the viscosity of the slag by adding desulfurization waste, smooth operation was possible with an overall air ratio of 0.47. The calorific value of the generated gas also improved from 880 Kcal/Nm ³ to 1012 Kcal/Nm ³ . After the experiment, we measured the viscosity of the slag taken out and found that the viscosity of the slag before adding desulfurization waste was
The viscosity was 230 poise at 1400°C, but after addition it was 115 poise at the same temperature, indicating a decrease in viscosity.

Example 2 Almost the same operation as in Example 1 was carried out using powdered dolomite as the desulfurization agent. By adding used dolomite to the combustor section of the gasifier, the flow of slag from the bottom of the furnace becomes extremely smooth, and the calorific value of the generated gas decreases from 876 Kcal/Nm ³ before input.
Improved to 1005Kcal/Nm ³ .

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional spouted bed type coal gasification process, and FIG. 2 is an explanatory diagram of one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Entrained bed coal gasifier, 2... Combustor section, 3... Reactor section, 5, 9... Pulverized coal supply line, 6, 8... Gasifier supply line, 18...
... _H2S absorption device, 19...regeneration device, 22...waste discharge line.

Claims (1)

[Claims] 1. Gasifying the raw material coal with a smaller amount of air and/or oxygen than its stoichiometric amount,
In the slug-tap coal gasification process that produces gas whose main components are CO and _H2 , used waste from desulfurization agents to remove the sulfur content from the crude gas is fed into the high-temperature section of the gasifier. A spouted bed coal gasification process characterized by: