JPH03182593A - Gasifier - Google Patents

Abstract

PURPOSE:To make it possible to control the particle size of granulated slag by providing a gasifier with a means for controlling the surface temperature of molten slag when it comes into contact with cooling water. CONSTITUTION:A pulverized solid raw material 1, such as pulverized coal, and an oxidizing agent are fed into a gasifier body 60 heated to a temperature above the melting temperature of ash of the raw material 1 to effect gasification, and molten slag 66 comprising molten ash is allowed to flow through a slag tap 63. After controlling the surface temperature of the slag 66 by means which comprise a means for measuring the surface temperature of the slag 66 at the slag tap 63, a means for calculating the flow rate of the slag 66, a means for calculating a flow distance necessary for the slag 66 to be cooled to a preestablished temperature based on the measured surface temperature and flow rate of the slag 66, and a means for controlling the level of water in a cooling water reservoir 64 based on the calculated distance, the molten slag 66 is cooled and granulated by cooling water 2 in a cooling section.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coal gasification device, and more particularly to a coal gasification device that can recover slag with a substantially constant particle size and high added value.

[Conventional technology]

Conventionally, coal gasifiers used in coal gasifiers include:
Various methods such as fixed bed, fluidized bed, and spouted bed have been proposed. Hereinafter, a spouted bed type gasifier will be explained as an example.

A spouted bed gasifier uses pulverized coal or char (
There is a two-stage furnace in which carbon particles (which are scattered with the gas) and gasifying agent (oxygen or air) are blown into the same burner, and a burner in which only pulverized coal or char is blown in in addition to the burner. There are several types of furnaces, and two-stage furnaces generally provide higher gasification efficiency.

The coal gasification reaction can be roughly divided into the following equations.

Coal → Char, H, Co, Co2. CH, -(1) Char+0□→Co,, Co, H,...(2) Coal+02→CO, Co2. H2・・・・・・・・・(3
) Equation (1) is a thermal decomposition reaction, which is likely to occur in the two-stage system described above by a burner that blows only pulverized coal alone. A typical example of a system in which the reactions of formulas (1) and (2) are clearly distinguished and simultaneously occur is the BI-GAS process in the United States, as is well known.

There is also a process based on the reaction of formula (3) in which coal and gasifying agent are supplied simultaneously from a burner and the formula (1) and formula (2) are intentionally not distinguished. A typical example is Texac.

process, Shell-K oppers process, etc.

The present inventors also, for example, Patent III No. 58-47162
and Japanese Patent Application No. 58-50496, a two-stage system in which a plurality of burners with different oxidizing agent distributions are installed in two stages in the furnace,
We are proposing a process that achieves high gasification efficiency. As an example of the conventional method, FIG. 9 shows a schematic system diagram of a two-stage gasifier proposed by the present inventors. Burners 68 and 69 for supplying a raw material 1 such as pulverized coal, a raw material carrier gas 30, and an oxidizing agent 40 are installed in the upper and lower stages of the gasification chamber 67 of the gasifier main body 1, and the oxidizing agent 40 is supplied to the upper stage burner 68. The lower burner 69 is charged with a larger amount. Here, in order to prevent the oxidizing agent from entering the supply hopper 17, in consideration of safety, nitrogen or carbon dioxide gas, which is an inert gas, is generally used as the raw material carrier gas 30.

The gasification chamber 67 is formed by lining the inside of the gasification furnace body 60 with a heat insulating refractory material 61.

Further, the m feed 1 is transferred from the supply hopper 17 to the feeder 20.2.
1 to the burners 68 and 69 via the ejectors 33 and 34 and the conveyor lines 35 and 36, and the generated gas 92 is taken out from the top of the gasifier body 60.

In this method, in particular, by distributing the oxidizing agent 40 as described above, in the lower burner, coal +02 → CO□ + H20 (4), and in the upper burner, coal +02 → CO□ + H20 (5) )Char+H
20+H, +CO... These make the reaction (6) more likely to occur. That is, the lower stage burner 69 distributes a large amount of the oxidizing agent 40 to heat the vicinity of the hole (slag tap) 63 provided at the bottom of the gasification chamber through which the molten slag 66 flows down, and the upper stage burner 68 generates active char. Then, by the gasification reactions of equations (5) and (6),
- The aim is to obtain a gas rich in carbon oxides and hydrogen. On the other hand, the molten slag 66 flows down from the slag tap 63 in a high temperature state and flows into the cooling water 2 stored at the bottom of the gasifier main body 60, and the molten slag is broken into pieces by the thermal shock at that time. Ru.

[Problems to be solved by the present invention]

As mentioned above, in this type of gasifier, the lower burner 6
A large amount of oxidizing agent 40 is distributed to 9 to raise the temperature near the slag tap 63, and the ash in the raw material is made to flow down from the slag tap 63 as molten slag, and the molten slag is crushed by the thermal shock when it flows into the cooling water 2. do. The crushed slag is intermittently discharged together with the cooling water by opening and closing the valve 90. The granulated slag recovered in this way is
Used as raw material for blast furnace cement, thin tube material for concrete, civil engineering material, etc. However, in the conventional method, cooling water 2
Since the slag was operated to maintain a constant water level, depending on the amount of raw material supplied or the type of raw material, the particle size of the granulated slag may become non-uniform. Therefore, when granulated slag is used for the above-mentioned purposes, it is necessary to make the particle size uniform by a classification operation using a sieve or the like, or a crushing/classification operation using a mill.

Furthermore, when the gasifier is started, the flow of molten slag is unsteady, so the molten slag is not crushed.

Slag may not be able to be discharged from valve 90.

Therefore, a crusher must be provided in the cooling water at the bottom of the gasifier to crush the large slag particles.

If a crusher is installed, in addition to the equipment cost, the furnace itself will also be larger, which will further increase the equipment cost.On top of that, the power cost for the crusher will also be required, and the cost of crushing the slag will be large. .

An object of the present invention is to control the particle size of granulated slag by managing the granulation conditions of molten slag flowing down from a slag tap.

[Means to solve the problem]

The above-mentioned problem is solved by supplying pulverized solid raw material such as pulverized coal together with an oxidizing agent to a furnace heated to a temperature higher than the melting temperature of the ash of the pulverized solid raw material and gasifying it. This is achieved by equipping the gasifier with means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water into a gasification device that allows the molten slag to flow down from a slag tap on the floor and is cooled and pulverized by cooling water in the lower part of the furnace. .

The above problem also arises because the means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water is based on the temperature of the molten slag before it comes into contact with the cooling water. This is also achieved by the gasifier according to claim 1, which is means for controlling the water level of.

The above problem also requires that the means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water includes means for measuring the surface temperature of the molten slag in the slag tap, means for calculating the flow rate of the molten slag, and means for calculating a flow distance required for the temperature of the molten slag to be cooled to a preset surface temperature of the molten slag based on the measured surface temperature and the flow rate; and the calculated distance. This is also achieved by the gasifier according to claim 1, comprising means for controlling the water level of the cooling water reservoir based on.

The above problem is also solved by the fact that the means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water consists of a plurality of spray nozzles arranged vertically on the wall of the gasifier furnace below the slag tap, and a means for measuring a surface temperature of the molten slag, a means for calculating a flow rate of the molten slag, and a means for adjusting the temperature of the molten slag to a preset surface temperature of the molten slag based on the measured surface temperature and the flow rate. means for calculating a downstream distance required for cooling to a temperature of 100 nm, and means for selecting a spray nozzle from among the plurality of spray nozzles based on the calculated distance and spouting cooling water from the spray nozzle. This is also achieved by the gasifier according to claim 1, comprising:

The above problem is further solved by the means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water, by increasing the distance from the slag tap to the position where the molten slag contacts the cooling water by L [ml
, where the flow rate of molten slag flowing down from one slag tap is Q [Q/h], it is controlled so that L≦Q0−. be done.

[Effect]

The molten slag flowing down from the slag tap is broken into pieces by thermal shock when it comes into contact with cooling water. The higher the surface temperature of the molten slag, the greater the thermal shock at this time. Therefore, the higher the surface temperature of the molten blade lug when it comes into contact with the cooling water, the finer the slag will be.
According to experiments conducted by the present inventors, when the surface temperature of molten slag in contact with cooling water is 900±50°C, the size of granulated slag is 2 to 3 + amφ, and when it is 1100±50°C, it is 1 to 2 mmφ. , and above 1300℃, lsmφ
The following fine granulated slag is produced. Therefore, by controlling the surface temperature of the molten slag when it comes into contact with cooling water, granulated slag with a uniform particle size can be recovered.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

Large Difference - Example] - The spouted bed gasifier which is the first embodiment of the present invention shown in FIG. The gasifier includes a gasifier section that gasifies the raw material, and a cooling water control section that controls cooling water stored in the gasifier main body. This cooling water control section serves as a means for controlling the surface temperature of the molten slag when it comes into contact with cooling water.

The raw material supply section includes a normal pressure hopper 10 into which the raw material 1, which is pulverized coal, is input, a pressurized hopper 14 connected and arranged below the normal pressure hopper 10 via a valve 11, and the pressurized hopper 14. A supply hopper 17 connected and arranged below the supply hopper 17 via a valve 15, a feeder 20.21 connected and arranged below the supply hopper 17 via a valve 18 or 19, respectively; 21, a conveyor line 35, 36 connected to the ejector 33 or 34, respectively, a valve 31, 32 connected to the ejector 33, 34 to supply the raw material conveying gas 30, and a valve 31, 32 connected to the pressurizing hopper 14. and a valve 16 connected to the feed hopper 17.

The gasifier section is formed by a cylindrical gasifier main body 60 arranged with its axis substantially vertical, and an interior of the gasifier main body 60 near the lower center in the vertical direction lined with a heat insulating refractory material. a gasification chamber 67 and a slag tap 63 which is an opening formed at the bottom of the gasification chamber and through which the molten slag 66 flows down.
The gasification chamber outlet 62, which is also an opening formed at the top of the gasification chamber 67, is arranged in upper and lower stages in the gasification chamber 67, and is connected to the transport lines 35 and 36 to transport the raw material 1 and the raw material. Burner 68 for supplying gas 30 and oxidizer 40
, 69, and the gasifier body 60r below the slag tap 63.
An ignition temperature rising burner 65 provided on the i-plane and a cooling water reservoir 64 provided at the bottom of the gasifier main body 60 and storing cooling water 2
and a slag discharge valve 9 connected to the cooling water reservoir 64.
It is equipped with 0 and . The burners 68 and 69 contain an oxidizing agent 4
Oxidant supply lines 41,42 supplying 0 are connected to each other, and a valve 43,44 is installed in each of the oxidant supply lines 41,42.

The cooling water control section includes an infrared thermometer 53 installed floating on the water surface of the cooling water 2, a level meter 59 installed on the wall of the gasifier main body 60 to detect the cooling water level, and a cooling water reservoir. 64 to supply cooling water, a solenoid valve 54 interposed in the cooling water line 55, and a cooling water discharge solenoid valve 121 connected to the cooling water reservoir 64.
and a controller 50 connected to the level meter 59, infrared thermometer 53, solenoid valve 54 and cooling water discharge solenoid valve 121 through control signal lines 58, 51, 52, and 122, respectively.
It is equipped with. The infrared thermometer 53 detects the surface temperature of the molten slag in a non-contact manner when the molten slag flows into the cooling water, and may be a radiation thermometer. In order to granulate molten slag, it is desirable to increase the surface temperature of the slag, and the higher the surface temperature of the molten slag, the smaller the particle size of the granulated slag. At 900±50℃, the particle size of granulated slag is 2-3m+mφ, 1100±50℃
1~2mmφ when , 1+**φ above 1300℃
The following fine granulated slags are viable. The experimental results of the present inventors are shown in FIGS. 2 and 3. Figure 3 schematically shows granulated slag of 2 to 3 IIIφ recovered when the molten slag was introduced into cooling water at a surface temperature of 900°C, and Figure 2 shows the molten slag at a surface temperature of 1300°C. 11II+φ recovered when flowing into cooling water at ℃
It is a figure showing the following granulated slag. Therefore, the surface temperature when the molten slag contacts the cooling water is very important.

By controlling this surface temperature, it becomes possible to adjust the particle size of the granulated slag. However, in reality, when the molten slag flows down from the slag tap, it loses heat to the atmospheric gas, so it gradually cools down and its surface temperature decreases as it moves further away from the slag tap. Therefore, the temperature of the molten slag in the slag tap and the surface temperature when it flows into the cooling water are different. Therefore, in this embodiment, the surface temperature T of the molten slag flowing into the cooling water is directly measured without contact using a thermometer 53 floating on the surface of the cooling water, and the particle size of the granulated slag desired by the granulation conditions is determined. The cooling water level was controlled to maintain the same level. The controller 50 performs a comparison calculation between the granulated slag temperature: To corresponding to the desired particle size of the granulated slag and the measured surface temperature T. At this time, assuming that the allowable value of the temperature difference of the surface temperature T with respect to To is α, T, -T)α ・Old... If (7), the solenoid valve 54 is opened and cooling water is supplied to the cooling water reservoir 64. , the level of the cooling water 2 is increased to make the temperature difference less than α. Also.

T, -T(-α...(8
), the cooling water discharge solenoid valve 121 is opened and the cooling water 2 is discharged from the cooling water reservoir 64, thereby lowering the level of the cooling water and making the temperature difference less than α. However, the level of the cooling water is detected by a level meter 59 and controlled so as not to exceed the upper and lower limits.

The controller 50 repeats the above operation and always keeps IT, -T
The level of cooling water is controlled so that I<α (9). Therefore, since the surface temperature of the molten slag when it flows into the cooling water is maintained within a predetermined temperature range, the slag granulation conditions become approximately constant, and granulated slag with a uniform particle size is recovered.

FIG. 4 is a schematic diagram of a spouted bed gasifier according to a second embodiment of the present invention. In the first embodiment, the surface temperature of the molten slag 66 when it flows into the cooling water 2 is actually measured, and is set to a predetermined granulation temperature T. The cooling water level was controlled so that the temperature difference between the
From the temperature of the molten slag 66 when it flows down from the slag tap 63, the surface temperature of the molten slag when it flows into the cooling water is estimated. The difference between this embodiment and the first embodiment is that a plurality of infrared cameras 101 and cooling water level meters 59 are installed at the bottom of the gasifier to measure the surface temperature of the molten slag flowing down from the slag tap. The infrared thermometer 53 is not provided, and their signals are connected to the control line 1.
02 and 58 to the controller 50. Also, a load cell 37 is provided to measure the weight of the fine powder raw material in the supply hopper 17, and its signal or the rotation speed of the feeders 20 and 21 that quantitatively supplies the fine powder raw material. It consists in that at least one of the signals is input to the controller 5o by a control signal line 56 or 57. The other constituent parts are the same as those in the first embodiment, and are given the same reference numerals and explanations will be omitted.

The controller 50 first controls the weight reduction rate of the load cell 37 attached to the supply hopper 17 or the feeder 20.
The supply amount of the fine powder raw material is determined from at least one information on the rotation speed of 21. When the supply amount is determined, the controller 5°
The flow rate of the molten slag flowing down from the slag tap 63 is calculated based on the preset value of the ash content ratio of the fine powder raw material.

In addition, the infrared camera 101 measures the surface temperature of the molten slag as it flows down from the slag tap, but in reality, when the molten slag flows down from the slag tap, it gradually cools down because the atmospheric gas takes away its heat. It turns out. Therefore, the granulation temperature of the molten slag corresponding to the desired particle size of the granulated slag is 1゛.

It is necessary to understand the distance that the slag flows down from the tap until it is cooled down to This distance can be easily calculated by the controller 50 using the infinite cylinder heat conduction model if the temperature of the molten slag and the flow rate of the molten slag when flowing down from the slag tap described above are known.

On the other hand, the present inventors calculated the flow rate of molten slag flowing down from one slag tap: Q [11/h] and the distance ill from the slag tap when the molten slag contacts the cooling water.
: An experiment was conducted by changing L [m], and the granulation property of the molten slag was confirmed. The results are shown in FIG. In the figure, 0 represents that the slag was granulated, and Δ represents that it was not granulated.

If we connect the fracking and non-fracking environments with a solid line, the area below this solid line will be the fracking area. Here, when the boundary value is expressed by a relational expression between L and Q, it becomes as follows.

L = QB・1...
(10) That is, the value of L is set to the boundary value Q, which is 0.
If the value is set to a value smaller than the fourth power, the molten slag will definitely be granulated.

Therefore, the controller 50 uses the solenoid valve 54, the solenoid valve 121 for cooling water discharge, and the level meter 59 to control the level of the cooling water level within a range below the boundary value of L expressed by equation (10) in FIG. In addition, since the control is performed to match the distance from the slag tap determined from the heat conduction model of an infinite cylinder, the slag granulation conditions become almost constant, and granulated slag with uniform particle size is recovered.

FIG. 6 is a schematic diagram of a spouted bed gasification system according to a third embodiment of the present invention. In the embodiment shown in FIG. 4, as a means for determining the surface temperature of the molten slag as it flows into the cooling water, an infrared camera 101 is provided to measure the temperature of the molten slag as it flows down from the slag tap. In this embodiment, as a means for this purpose, a thermometer 103 such as a thermocouple that detects the temperature of the molten slag in the gasification chamber 67 is installed in place of the infrared camera 101. The other constituent parts are the same as those in the second embodiment, and are given the same reference numerals and explanations will be omitted. The temperature of the molten slag present in the gasification chamber is normally equal to the temperature of the molten slag as it flows down from the slag tap.

Therefore, if possible, it is preferable to directly measure the temperature with the thermocouple 103 attached to the bottom of the gas storage 67, but it is also possible to measure the temperature at another location in the gasification chamber and estimate the temperature of the molten slag. The method of controlling the surface temperature of the molten slag at this time is the same as the control method shown in FIG.

Figure 7 is a schematic diagram of a spouted bed gasifier according to a fourth embodiment of the present invention. In the second embodiment shown in FIG. 4, a method was used to change the level of the cooling water to change the position where the molten slag contacts the cooling water, but in this embodiment, the cooling water for granulation is ejected from a spray nozzle, and by changing the position of this spray nozzle, the position where the molten slag contacts the cooling water can be changed.

The difference between this embodiment and the second embodiment is as follows.

A valve 115 is provided in place of the solenoid valve 121 for discharging cooling water, and a pressurized cooling water line 112 is provided with a switching valve 113 in place of the cooling water line 55 provided with the solenoid valve 54.
is provided, and a plurality of spray nozzles 111 connected to the switching valve 113 are connected to the gasifier main body 6 below the slag tap.
0, and a collision plate 114 extending in the vertical direction is provided at a position facing the spray nozzle below the slug tap. The spray nozzles 111 are arranged in rows at predetermined intervals in the vertical direction, and the nozzles are oriented in order to prevent splashes of pressurized water ejected from the nozzles from entering the gasification chamber 67.
It is in the axial direction of the gasifier main body 60 and diagonally downward. The switching valve 113 is.

A plurality of spray nozzles 11 connected to the switching valve 113
The pressurized cooling water line 112 is configured to be able to be switched to communicate any one of the nozzles with the pressurized cooling water line 112. The other components are the same as those in the second embodiment, so the same reference numerals are given and the explanation will be omitted.

In this embodiment, the controller 50 uses the surface temperature of the molten slag detected by an infrared camera as it flows down the slag tap and one of the control signal lines 56 and 57, as in the second embodiment. The position where the surface temperature of the molten slag reaches a predetermined temperature, that is, the distance from the slag tap, is calculated based on the molten slag flow rate calculated based on the input signal.

The controller 50 then switches the pressurized water supplied from the pressurized cooling water line 112 to the spray nozzle 11 located at the position closest to the calculated position using a switching valve 113.
1 and spray pressurized water onto the flowing molten slag. In addition, in this embodiment, as shown in FIG. 7, a collision plate 114 is installed below the slag tap, and the spray nozzle 111
The molten slag rapidly cooled by the pressurized water jetted from the collision plate 114 is struck by the jetting force of the pressurized water,
The molten slag is further finely ground. However, in this embodiment, in order to keep the amount of cooling water held in the cooling water reservoir at the lower part of the gasifier almost constant, at the same time that pressurized water is continuously supplied from the spray nozzle, the valve 115 is opened and the cooling water in the cooling water reservoir is is continuously discharged.

FIG. 8 is a schematic diagram of a spouted bed gasifier according to a fifth embodiment of the present invention. As a means for changing the position where the molten slag contacts the cooling water, a plurality of spray nozzles 111 and a switching valve 113 are installed at the bottom of the gasifier, similar to the embodiment shown in FIG. The supplied pressurized water is supplied by the switching valve 113 to the spray nozzle 111 located closest to the distance from the slag tap calculated by the controller 50, and the pressurized water is sprayed onto the flowing molten slag. The difference between this embodiment and the embodiment shown in FIG. 7 is that the temperature of the molten slag is detected by a thermometer 103 that detects the temperature of the molten slag in the gasification chamber 67, similar to the method shown in FIG.
The point is that it is done by.

When the temperature of the molten slag flowing down from the slag tap is low, a heating burner 65 for heating the slag tap is ignited to heat the molten slag flowing down from the slag tap,
By changing the amount of heat input to the temperature increasing burner, the surface temperature of the molten slag when it comes into contact with the cooling water may be controlled.

Alternatively, the surface temperature of the molten slag may be controlled when it comes into contact with the cooling water by blowing a low-temperature gas such as an inert gas or a recycled gas of the gas produced in the gasifier onto the molten slag flowing down from the slag tap. .

Furthermore, the surface temperature of the molten slag when it comes into contact with the cooling water may be controlled by changing the temperature of the atmospheric gas surrounding the 18@slag flowing down between the slag tap and the surface of the cooling water.

〔Effect of the invention〕

According to the present invention, the particle size of the granulated slag can be adjusted within a range of approximately 31φ or less, and the particle size can be made uniform, so that classification operations using a sieve or the like or crushing and classification operations using a mill can be performed. It can be used widely as raw material for blast furnace cement, fine aggregate for concrete, civil engineering material, etc.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a schematic system diagram of a spouted bed gasifier according to the first embodiment of the present invention, and FIGS. 2 and 3 show slag granulation carried out by the present inventors. FIG. 4 is a plan view showing particles of granulated slag collected in the experiment. FIG. 4 is a schematic diagram of a spouted bed gasifier according to the second embodiment of the present invention. FIG. Graphs 6, 7, and 8 showing the relationship between contact with cooling water and distance from the slag tap show spouted layer gas of the third, fourth, and fifth embodiments of the present invention. FIG. 9 is a schematic diagram of a conventional spouted bed gasifier. 1... Fine powder solid raw material, 2... Cooling water, 37... Load cell, 50... Controller, 50.52, 56, 57
, 58, 102, 104° 122... Control signal line, 53... Infrared thermometer, 54... Solenoid valve, 55...
・Cooling water line, 59...Level meter, 60...Gasifier body, 63...Slag tap, 64...Cooling water reservoir, 65...Ignition/heating burner, 66...Melting Slag, 67...Gasification chamber, 68.69...Burner. 101...Infrared camera, 103...Thermometer. 111... Spray nozzle, 112... Pressurized cooling water line, 1 13... Switching valve, 114... Collision plate, 21... Solenoid valve for cooling water discharge.

Claims (1)

[Claims] 1. A pulverized solid raw material such as pulverized coal is supplied together with an oxidizing agent to a furnace heated to a temperature higher than the melting temperature of the ash of the pulverized solid raw material and gasified, and the molten ash is molten ash. A gasifier in which slag is caused to flow down from a slag tap in a hearth, and is cooled and pulverized by cooling water in the lower part of the furnace, comprising means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water. A gasifier featuring: 2. The means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water controls the water level of the cooling water reservoir provided at the bottom of the gasifier based on the temperature of the molten slag before it comes into contact with the cooling water. The gasification apparatus according to claim 1, characterized in that it is a means. 3. The means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water includes means for measuring the surface temperature of the molten slag in the slag tap, means for calculating the flow rate of the molten slag, and the measured surface temperature. means for calculating a flow distance necessary for cooling the molten slag to a preset surface temperature of the molten slag based on the flow rate; and a cooling water reservoir based on the calculated distance. 2. The gasifier according to claim 1, further comprising: means for controlling the water level of the gasifier. 4. The means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water includes a plurality of spray nozzles arranged vertically on the wall of the gasifier furnace below the slag tap, and a means for controlling the surface temperature of the molten slag at the slag tap. a means for measuring the flow rate of the molten slag, a means for calculating the flow rate of the molten slag, and a temperature of the molten slag is cooled to a preset surface temperature of the molten slag based on the measured surface temperature and the flow rate. and means for selecting a spray nozzle from the plurality of spray nozzles based on the calculated distance and spouting cooling water from the spray nozzle. The gasifier according to claim 1, characterized in that: 5. The means for controlling the surface temperature of the molten slag when it comes into contact with the cooling water is such that the distance from the slag tap where the molten slag contacts the cooling water is L [m], and the molten slag flowing down from one slag tap is When the flow rate of is Q [l/h], L≦Q^0^. 4. The gasification apparatus according to claim 1, wherein the gasification apparatus is controlled to be ^4.