JPS6015491A - Equipment and method for coal gasification - Google Patents

Abstract

PURPOSE:To reduce the tar content of produced gas effectively in coal gasifying equipment by using a fluidized gasifying oven in which the height of fluid layer is sufficiently larger than the inner diameter of the oven. CONSTITUTION:In a fluid layer gasifying oven 1, the height L of the fluid layer is set at least four times larger than the inner diameter D of the oven. Steam is fed through an inlet 5 and dust coal and air are introduced through an inlet 2 for gasification of coal. Low (or medium) calorie gas produced is taken out through an outlet 6 and granulated coal and ash are discharged through an outlet 3. Tar produced in a combustion zone at the bottom of a fluid layer 4 ascends in the fluid layer 4 together with air bubbles 7 to a sufficient height and is decomposed in the way, thus controlling inclusion of tar in the produced gas. The effect is increased, since dust coal is carried by stream of air and loaded at the bottom of the gasifying oven.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a coal gasification apparatus and a coal gasification method.

As is well known, a coal gasifier having a fluidized gasifier is used to gasify coal to produce low-calorie gas or medium-calorie gas. By the way, the fluidized gasifier has the following advantages: [x;i] It can use powdered coal that cannot be used in an electric bed, it gasifies at a relatively low temperature compared to a spouted bed, so it consumes relatively little oxygen, and compared to a solid V bed it consumes less water vapor. It has several features such as low consumption h1, easy start and stop, and good melting of gas and solids, so it has a large processing capacity and is suitable for a dog capacity J11.

Conventionally, methods for supplying coal into a gasifier with a flow rate of 1 include a method using a screw 74-der, a method using air flow conveyance such as N2 gas or air, a method supplying coal from the middle part of the gasifier,
Alternatively, other methods such as supplying the gas from the bottom of the gasifier have been tried.

Furthermore, the flow MJJJ layer W6 in the gasifier has been studied only from the viewpoint of the reactivity of the coal gasification reaction and the pressure loss of the supplied gas.

However, as coal is gasified, tar, which is a hydrocarbon-based compound, is generated, and the generation of this tar indicates a decrease in the coal's purple dust conversion rate. Unfortunately, this tar was included in the generated gas and transported, causing problems with condensation in the flue.

The present invention was made in response to the above-mentioned desire, and an object of the present invention is to provide a coal gasification apparatus and a coal-sulfurization method that can reduce the amount of tar in generated gas.

That is, the invention of D1 of the present application is based on lowering the temperature of tar in the generated gas by increasing the ratio of the height of the fluidized bed to the inner diameter of the fluidized bed gasifier by more than 4. be.

Further, the second invention of the present application is similar to the first invention in that the coal is supplied to the fluidized bed gasifier by air flow conveyance from the bottom g1s of the fluidized bed gasifier. The aim is to obtain the following effects.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A coal gasification apparatus according to an embodiment of the present invention will be described below with reference to FIG.

1 in the figure is a cylindrical air flow conveyance type fluidized bed gasifier with an inner diameter. A coal/gas inlet 2 and a granulated coal and ash outlet 3 are provided at the lower end of the gasifier l.

Coal powder of several diameters or less, which has been generally fed through the inlet 2 by air or oxygen, is vigorously injected into the fluidized bed 4 having a height L. In addition, the above-mentioned inner diameter and flow ゛1
The relationship between the helmet I% and L is 4 (L/D). Further, a water vapor inlet 5 is provided in the lower wall of the gasifier 1. Furthermore, a gas outlet 6 is provided at the upper end of the gasifier 1 for extracting the generated gas produced in the gasifier 1.

Next, these 41 Imazou outfits! E,'ff: The coal gasification method used will be explained. That is, the coal powder is supplied from the fathom 2 at the lower end (bottom) of the gasifier 1 by, for example, air currents 1 and 5. As a result, tar is generated in the melted part 4 at the bottom of the fluidized bed 4, and as the fluidized bed 4f rises with the bubbles 7, it is separated by ash)
γ is promoted and reduced by thermal decomposition. In addition to this, the higher the height L of the fluidized bed 4, the longer the contact time of the bubbles 7 with the powder, so that the decomposition reaction of tar also progresses. Here, the size of the bubbles 2 is proportional to the inner diameter of the gasifier 1, and as the bubbles 7 become thicker, the contact surface between the gas inside the bubbles and the powder outside the bubbles decreases, so generally the reaction rate is L. /D, and the larger L/)) is, the more the tar produced in the gasifier 1 can be reduced.

According to the present invention, since the structure is such that the relationship between the inner diameter of the fluidized bed gasifier 1 and the fluidized bed height L is L/D>4, the combustion of the fluidized bed 6) Furnace! .

The tar generated in the process can be reduced by pyrolysis and promoted decomposition by charcoal.

Further, since the coal powder is supplied to the fluidized bed gasifier 1 by air flow conveyance from the bottom of the gasifier 1, the same effects as described above can be obtained.

Experimental example! ! Using the coal gasifier shown in Figure 1, the following test conditions were carried out: Temperature inside the fluidized bed was 870°C, pressure was below i<g/rrnQ, coal supply - M5 kg/h, and air and steam supply amounts were each 10 Nm5. /h-1kg/h, and the inner diameter of the yx reactor 1 is 106n, and when the height of the fluidized bed L and the tower length of the gasifier 1 are changed, tar is generated in the gas. The characteristic diagram shown in the figure was obtained. In the figure, the horizontal axis indicates the height of the h layer of stream 1, and the vertical axis indicates the amount of tar generated in the generated gas. The same figure shows that the fluidized bed sieve is 40.
It was confirmed that most of the tar was removed near the ctn.
You can check it. That is, as mentioned above, since the inner diameter of the gasifier 1 is 1Ocrn, L/1)=4. Therefore, it is clear that most of the tar can be removed with L/D ) 4. In addition, tar generated when air is used for air flow conveyanceg! , is 0.1,! 7/l-: 9.coal, and when N2 was used for airflow conveyance instead of air, the tar generation fii was 0.4 g/kg.coal.

As detailed above, according to the present invention, it is possible to provide a highly reliable coal gasification apparatus and coal gasification method that can sufficiently reduce tar in generated gas.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a coal gasification apparatus according to an embodiment of the present invention, and FIG. 2 is a characteristic diagram showing the relationship between the height of the fluidized bed and the amount of tar generated in the produced gas by the apparatus shown in FIG. be. DESCRIPTION OF SYMBOLS 1... Flow rfIh bed gasifier, 2... Coal/gas barrel inlet, 3... Granulated coal and ash outlet, 4... Fluidized bed, 5... Steam inlet, 6 ...Gas outlet, 7...
・Bubbles.

Claims (1)

[Claims] 1. In an apparatus for producing a low-calorie gas or a medium-calorie gas by converting coal into a gas in a fluidized bed gasifier, the ratio of the height of the fluidized bed to the inner diameter of the fluidized throat gasifier is 4. A coal gasifier characterized by being larger. 2. In an apparatus for producing low-calorie gas or medium-calorie gas by converting coal into a dynamic gasification furnace at θ1, υiL dynamic no-gasification - supply of coal to the furnace ks'
A coal gasification method that is characterized by air flow conveyed from the bottom of a 1t1 gasifier.