JPH07103383B2 - Pulverized coal gasification method - Google Patents

Description

The present invention relates to a method for gasifying pulverized coal, and more particularly to a method for gasifying pulverized coal capable of preventing the generated slag from solidifying and discharging it continuously and stably. .

As part of the diversification of energy sources, various attempts have been made to obtain gaseous fuel by gasifying pulverized coal.
Conventionally, this type of method has been shown in FIG.
Pulverized coal sent to the oxygen-containing gas (generally oxygen) sent through the supply port 9 and steam line 10, the same valve
It is carried out by spraying and supplying the gasification section 1 in the gasification furnace 7 while mixing the steam sent via 11 and partially burning it. The gas produced by the partial combustion is
After going up in the gas furnace 7, it is sent to the produced gas line 17 from the top thereof, and is passed through a heat recovery device such as a cyclone or a waste heat boiler, which is optionally provided, and then recovered as a cold gas.

On the other hand, molten slag is generated due to the ash content in the coal, but this slag passes through the tap port 3 provided at the lower part of the gasification furnace 7 and then flows down into the quench water 6 below, where it solidifies. It is collected from the slag discharge port 19.

However, in such a conventional method, the following drawbacks cannot be avoided. That is, as shown in FIG. 2 (a partially enlarged view of the gasification furnace shown in FIG. 1), the molten slag 2 produced by the partial combustion moves along the slope of the bottom of the gasification furnace, and then the tap hole is formed. When it reaches 3 and then flows down along its inner peripheral surface, the fluidity of the slag changes drastically, and while the upper portion 5 of the lap mouth 3 exhibits high fluidity, the lower portion 4 thereof exhibits low fluidity, Finally, there is a risk of solidification.

The following are possible causes of the above.

Generally, the temperature of the gasification section 1 is kept at a high temperature of about 1,500 to 2,000 ° C in order to improve the utilization rate of carbon content in coal as much as possible. Is maintained at a high enough temperature to keep it in a highly fluidized state. However, the quench water 6 (100
Heat is taken by radiant heat, etc. under the influence of (low temperature of ℃ or less), and the amount of heat transferred from the high-temperature gasification section 1 decreases in proportion to the distance (it becomes more prominent as the device becomes larger) As a result, the temperature decreases, and the fluidity of the slag decreases due to this effect.

In order to eliminate such a drawback, attempts have been made to increase the temperature of the gasification furnace excessively by increasing the supply amount of oxygen so as to increase the temperature of the lower portion 4 of the tap opening. In this case, the following problems newly occur. The first is that the quality of the obtained cold gas (the calorific value of the generated gas) is unavoidable, as is apparent from FIG. 3, and the second is that it becomes more difficult to select the material of the gasification furnace. is there. FIG. 3 shows that even if such a high temperature is attempted, slag discharge may not be stably carried out depending on the type of coal.

On the other hand, there is also a problem that it is difficult to accurately measure the slag temperature and the gasification temperature. That is, since these temperatures are high, it is difficult to directly measure them with, for example, a thermocouple, and even when they are indirectly measured with a radiation thermometer, there is a problem in limiting blackness (emissivity). However, accurate measurement is difficult, and overcoming these is a development issue.

An object of the present invention is to provide a pulverized coal gasification method capable of continuously and stably discharging slag without reducing gasification efficiency.

In order to achieve the above-mentioned object, the present invention sprays pulverized coal into a gasification furnace in the presence of an oxygen-containing gas and steam to gasify it, and melts slag of the ash generated at that time is tapped at the bottom of the gas furnace. In the gasification method of pulverized coal, which is made to flow down through the mouth to the quench water portion below to be recovered, the temperature detection portion is provided inside the lower furnace body of the tap opening, and the temperature detected by the temperature detection portion is provided. Is reduced to the melting temperature of slag or higher, and the amount of steam supplied to the gasification furnace is reduced.

Hereinafter, the present invention will be described in more detail with reference to the embodiments shown in the drawings.

FIG. 4 and FIG. 5 are respectively an explanatory view of a pulverized coal gasifier according to an embodiment of the present invention and an enlarged sectional view of a tap opening portion thereof, which are shown in FIG. 1 and FIG. The same reference numerals of the devices shown and the parts to which the same reference is made,
In general, from the inner peripheral surface of the lower part 4 of the tap opening 3 to 10 to
A temperature detector (generally a thermocouple) 18 provided at a position inside the 50 mm furnace body, and a gas vent provided in a space formed between the lower surface of the tap opening 3 and the water surface of the quench water 6 14 and a gas vent line 16 including a cooler 13 for cooling the gas withdrawn from the gas vent 14 and a gas regulating valve 15.
And a burner 12 directed to the lower opening of the tap opening 3.

In the apparatus having such a configuration, the degassing line 16 is closed and the burner 12 is not operated, and the line is
When the operation according to the present invention was carried out with the steam supply from 10 reduced and controlled, the results shown in I of FIG. 6 were obtained. In the figure, T ₁ is the temperature detected by the temperature detector 18, and T ₂ is the adiabatic flame temperature in the gasification section 1 (the supplied oxygen and the carbon content in the coal undergo a partial oxidation reaction). The theoretical calculation temperature based on the heat generated at this time) is shown. This result and the results of a separate related experiments, is not always uniform due to a difference in the melting point of the coal ash, generally T ₂ -T ₁ ≦ 200
It was confirmed that the slag would flow down sufficiently at ~ 800 ° C.

However, the above conditions are not sufficient conditions, and for comparison, the steam supply amount is increased (the oxygen supply amount may be decreased) at the time point A in FIG. 6 to decrease T ₂ (also T ₁ is However, in the region II, the condition of T ₂ −T ₁ ≦ 200 to 800 ℃ was satisfied, but the solidification phenomenon of slag was observed. From these, it is clear that the conditions of T ₂ −T ₁ ≦ 200 to 800 ° C and T ₁ ≧ slag melting point (flow temperature) are necessary to maintain the required flow state of slag. It was

In order to satisfy the above conditions without deteriorating the quality and efficiency of the produced gas, pulverized coal and oxygen-containing gas (oxygen,
It is sufficient to increase T ₁ by reducing the amount of steam supplied to the gasification furnace while supplying (air, etc.) at a constant ratio. At this time, an operation of increasing the amount of gas released to the gas release line or igniting the burner 12 can be used together.

The supply ratio of the above pulverized coal and oxygen-containing gas is not necessarily uniform depending on the coal type, but generally O ₂ / coal (weight) = 0.6-
It is desirable to set it to about 1.2.

Next, FIG. 7 shows a system of a pulverized coal gasification apparatus according to another embodiment of the present invention, and this apparatus is similarly referred to by the same reference numerals and description of the apparatus shown in FIG. Compare the part and the value T ₁ detected by the temperature detector 18 with the slag melting temperature entered in advance, and if the former is lower than the latter, reduce the steam supply from line 10 to eliminate this. And a steam amount controller 21 for outputting an operation signal to the steam valve 11 based on a signal from the arithmetic unit 20, and a gas control valve
It is mainly composed of a gas vent valve opening controller 22 for outputting an operation signal to 15 and a burner ignition controller 23 for outputting an operation signal to a fuel valve 25. In the figure,
24 is a degassing line for detecting the degassing amount and feeding this back to the degassing opening degree adjuster 22.
Gas flowmeters, 26 and 27, which are provided downstream of the 16 gas regulating valves, are heat recovery devices such as a cyclone and a waste heat boiler, which are provided in the produced gas line 17, if necessary.

In the apparatus having such a configuration, the temperature detector 18 T ₁
Although the operation is performed under the measurement of, when T ₁ does not reach the melting temperature of the slag at this time, first, an instruction signal is output from the arithmetic unit 20 to the steam amount adjuster 21, and thereafter, the adjuster is sequentially operated. 21 and steam valve 11 actuate to reduce the steam supply (initial steam supply, generally steam / coal = 0.1 to 0.3 by weight) and accompanying temperature of gasification section 1 (T ₂ ). Is achieved, which causes T ₁ to rise above a predetermined temperature. As a result, if the same coal is used, fluctuations in the ash melting point can be sufficiently absorbed by increasing or decreasing steam, and stable slag flow (solidification prevention) becomes possible.
In the present embodiment, in the case where T ₁ cannot be maintained at the predetermined temperature even after performing the above steam reduction, in addition to the above operation, the operation of further opening the gas regulating valve 15 installed in the gas vent line 16 Can be similarly performed through the instruction of the arithmetic unit 20 and the operation of the gas vent valve opening adjuster 22. As a result, the high temperature gas of the gasification section 1 can be extracted to the degassing line 16 via the tap port 3, the gas vent port 14 and the gas cooler 13, so that the tap port 3 is heated by the passing hot gas. You can

Since the gas extracted as described above joins with the subsequent product gas line 17 and is collected, the gasification efficiency is not reduced. The gasifier 7 is connected to the produced gas line 17.
Since the cyclone 26, the thermal boiler 27, etc., which cause pressure loss, are connected after the outlet of the gas outlet, the gas pressure in the subsequent part becomes lower than that in the gasification furnace 7. Therefore, the gas will flow naturally only by opening the gas regulating valve 15. It is desirable that the amount of degassing to the degassing line 17 be 50 to 20% or less of the total amount of generated gas.

Next, in the case where T ₁ cannot be kept at the predetermined temperature even by the above-described methods, in addition to the above-mentioned operations, the ignition of the burner 12 installed below the tap opening 3 is performed by the arithmetic unit 20.
It is also possible to forcibly heat the tap opening 3 by performing the same procedure through the above instruction and the operation of the burner ignition adjusting device 23. The burner 12 may be ignited during solidification prevention at the start and stop.

As described above, in this embodiment, the temperature of the slag is measured by the temperature detector 18 provided in the lower portion of the tap opening 3. However, when the detected temperature is not within the appropriate range, By automatically reducing the supply amount of steam, it becomes possible to control the above temperature to a predetermined level or higher, which can sufficiently prevent the solidification of the slag without lowering the efficiency.

As described above, according to the present invention, the detected temperature is equal to or higher than the melting temperature of the slag, by controlling the amount of steam supplied to the gasification furnace, without affecting the gas flow,
In addition, the slag temperature is raised without the need to supply excess oxygen, which causes a decrease in the quality of the produced gas and the production efficiency.
It is possible to prevent solidification of the slag and to carry out continuous and stable discharge of the slag accompanying it.

[Brief description of drawings]

FIG. 1 is a side sectional system diagram of a main part of a conventional pulverized coal gasifier, FIG. 2 is an enlarged side sectional view of a tap opening portion of the apparatus shown in FIG. 1, and FIG. FIG. 4 is a diagram for explaining the influence on the quality of cold gas, FIG. 4 is a side sectional view of a main part of a pulverized coal gasifier according to an embodiment of the present invention, and FIG. 5 is a tap of the device shown in FIG. An enlarged side sectional view of the mouth, FIG.
The figure which shows the effect of the Example of this invention with a comparative example, FIG. 7 is a systematic diagram of the pulverized coal gasification apparatus which concerns on the other Example of this invention. 1 ... Gasification part, 2 ... Slag, 3 ... Tap, 4 ...
… Lower tap port, 5 …… Upper tap port, 6 …… Quench water, 7 …… Gasification furnace, 8 …… Pulverized coal supply port, 9 …… Oxygen-containing gas supply port, 10 …… Steam line, 11… … Steam valve, 14 …… Gas vent, 15 …… Gas control valve, 16…
… Gas vent line, 17 …… Production gas line, 18 …… Temperature detector, 19 …… Slag discharge port, 20 …… Computer, 21 ……
Steam amount controller, 22 ... Gas vent valve opening controller, 23 ...
… Burner ignition control device, 24 …… Gas flow meter, 25 …… Fuel valve.

Continuation of the front page (56) Reference JP-A-58-29887 (JP, A) JP-A-54-117504 (JP, A) JP-B 31-10516 (JP, B1) JP-B 57-7200 (JP) , B2)

Claims (2)

[Claims] 1. A pulverized coal is atomized and supplied to a gasification furnace in the presence of an oxygen-containing gas and steam to gasify it, and molten slag of ash generated at that time is quenched through a tap port at the bottom of the gasification furnace to a lower quench. In the gasification method of pulverized coal which is made to flow down to the water part to be recovered, a temperature detecting part is provided inside the lower furnace body of the tap port, and the temperature detected by the temperature detecting part is equal to or higher than the melting temperature of the slag. So as to reduce the amount of steam supplied to the gasification furnace. 2. The gas of pulverized coal according to claim 1, wherein at least one operation selected from the above a, b, and c is one in which these operations are sequentially repeated. Method.