JP2012172080A - Coal gasification method in coal gasification apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coal gasification method in a coal gasification apparatus, by which even when low ash coal deficient in ash is gasified, optimum slag coating can be performed in a furnace by a simple method.SOLUTION: A modifier is added to raw coal serving as raw material for coal in such an amount as to adjust the ash content of the coal to 2-19 wt.%, preferably 6-10 wt.%.

Description

  The present invention relates to a coal gasification apparatus having a gasification furnace that partially oxidizes coal and gasifies it, and is capable of maintaining the slag coating in the gasification furnace at an appropriate amount that maximizes the operation efficiency. It is a technique related to the method.

Conventionally, as this type of coal gasifier, for example, techniques disclosed in Patent Documents 1 to 3 are known.
In the coal gasifier shown in Patent Publications 1 and 2, in the lower gasifier, oxygen or oxygen and water vapor and coal are introduced to generate gasified gas by partial oxidation, and the upper reformer Shows a system using a two-stage two-stage reactor in which coal and hydrogen are introduced into the generated gasified gas to generate gas, oil, and char by hydrothermal decomposition. And by making the reactor into two chambers and two stages in this way, it is possible to separate the part that performs gasification of coal and the part that performs hydropyrolysis, and to set the operating conditions of each part freely Become.

In the coal gasifier shown in Patent Publication 3, pulverized coal and a gasifying agent (oxygen-containing gas or the like) are injected into a gasification furnace pressurized at high temperature and partially oxidized in an internal gasification section. Thus, the product gas is obtained.
Further, in the gasification method of petroleum coke feedstock disclosed in Patent Publication 4, X (CaO, CaCO ₃ , MgO, MgCO ₃ , iron oxide, boron oxide, sodium oxide, potassium oxide and a mixture thereof are used. A technique for optimizing the slag viscosity by determining an optimum composition from a ternary system state composed of a selected basic ash component), Al ₂ O ₃ and SiO ₂ is shown.

JP 2008-174583 A Japanese Patent Laid-Open No. 2005-162896 JP 11-140464 A JP-T 9-505092

By the way, in the gasification furnace of the coal gasification apparatus shown in the above Patent Publications 1 to 4, the ash content in the coal becomes slag as a by-product, and the wall surface in the furnace is slag-coated, and a part of the slag coating melts. It becomes slag and is guided to a water tank (a water granulation unit) located below via a slag tap discharge hole at the lower part of the gasifier.
If the amount of the slag coating of the gasification furnace is insufficient, the heat removal from the water wall furnace is increased, and the supply amount of oxygen gas for maintaining an appropriate gasification temperature is increased. If the slag coating is excessive, the slag coating in the furnace will be maintained, but the amount of molten slag discharged outside the furnace will also increase, resulting in an increase in the amount of heat flowing out of the furnace and proper gasification. The supply amount of oxygen gas for maintaining the temperature increases.
That is, in the coal gasifier shown in the above patent publications 1 to 4, if an appropriate amount of slag coating is not maintained at an optimum amount, the supply amount of oxygen gas for maintaining the gasification temperature increases, and the gasifier is operated. There was a problem that the cost for doing so increased.

  Moreover, in patent document 4, although the technique which examines optimal coal composition from a ternary system state in order to aim at optimization of slag viscosity is shown, in order to obtain optimal coal composition, you must try and error. . In particular, when gasifying low ash coal (for example, the amount of ash is less than 2 wt%) that lacks ash, there is a problem that it is difficult to determine the raw material components based on the composition alone. In recent years, this type of low ash coal is suitably used in coal gasifiers.

  The present invention has been made in view of the above-mentioned circumstances, and even when gasifying low ash coal that lacks ash by a simple method, by performing optimal slag coating in the furnace, gas Provided is a coal gasification method in a coal gasifier capable of suitably maintaining the temperature in a gasifier.

In order to solve the above problems, the present invention proposes the following means.
Claim 1 of the present application is a coal gasification method in a coal gasification apparatus having a gasification furnace for partial oxidation of coal to gasify the coal so that the ash content of the coal is 2 to 19 wt%. It is characterized by adding a preparation agent to raw coal as raw material of coal.

According to the present invention, since the preparation agent is added to the raw coal so that the ash content of the coal is 2 to 19 wt%, the low ash coal with insufficient ash content is used as the raw coal for gasification. In addition, the slag coating in the gasification furnace is maintained at an appropriate amount, and the temperature drop in the furnace caused by the shortage or excess of the slag coating can be prevented. As described above, in the present invention, when the ash content of the low ash coal is gasified as the raw coal by a simple method of adding the preparation agent to the raw coal so that the ash content of the coal becomes 2 to 19 wt%. In addition, the optimum slag coating can be performed in the furnace, and the temperature of the gasification furnace can be suitably maintained and the efficient operation of the coal gasifier can be performed.
That is, if the ash content of coal is less than 2 wt%, the amount of slag coating in the gasification furnace becomes insufficient, heat removal from the water wall furnace (furnace wall) increases, and an appropriate gasification temperature is maintained. If the supply amount of oxygen gas increases and the amount of ash is greater than 19 wt%, the amount of molten slag discharged from the furnace increases due to excessive slag coating, resulting in outflow from the furnace. The amount of heat to be generated increases, and there is a problem that the supply amount of oxygen gas for maintaining an appropriate gasification temperature increases. However, in the present invention, since the preparation agent is added to the raw coal so that the amount of ash content of the coal becomes 2 to 19 wt%, when the gas is gasified using low ash coal with insufficient ash content as raw coal. Even so, the slag coating in the gasification furnace is maintained at an appropriate amount, and the temperature drop in the furnace caused by the shortage or excess of the slag coating can be prevented.
The ash content of coal means inorganic substances such as quartz, clay minerals, iron sulfide, and trace metals in organic matter.

  Moreover, according to the coal gasification method according to claim 2 of the present application, the preparation agent is added so that the ash content of the coal is preferably 6 to 10 wt%.

  According to the present invention, the slag coating in the gasifier is maintained at an optimum amount by adding the preparation agent so that the ash content of coal is preferably 2 to 19 wt%, preferably 6 to 10 wt%. Therefore, it is possible to reliably prevent a temperature drop in the furnace resulting from the shortage or excess of the slag coating.

  Further, according to the coal gasification method according to claim 3 of the present application, as the preparation agent, mineral powder such as limestone and cinnabar, oxide powder such as blast furnace slag powder, refractory material powder, various cement powders, and the like are used. It is characterized by that.

  According to the present invention, the ash content of coal is suitably adjusted by utilizing mineral powders such as limestone and straw, and oxide powders such as blast furnace slag powder, refractory powder, and various cement powders as a preparation agent. Is possible.

  According to the coal gasification method according to claim 1 of the present application, since the preparation agent is added to the raw coal so that the ash content of the coal becomes 2 to 19 wt%, the low ash coal with insufficient ash is used as the raw coal. Even in the case of gasification, the slag coating in the gasification furnace is maintained at an appropriate amount, and the temperature drop in the furnace caused by the shortage or excess of the slag coating can be prevented. That is, in the present invention, even when gasifying low ash coal with insufficient ash content as raw coal by a simple method of adding a preparation agent to the raw coal so that the ash content of coal is 2 to 19 wt%. The optimum slag coating can be performed in the furnace, and the temperature in the gasification furnace can be suitably maintained to operate the coal gasifier efficiently.

  According to the coal gasification method according to claim 2 of the present application, the preparation gas is added to the raw coal so that the coal ash content is 2 to 19 wt%, preferably 6 to 10 wt%. The optimal amount of slag coating in the conversion furnace is maintained, and temperature drop in the furnace caused by the shortage or excess of the slag coating can be reliably prevented.

  According to the coal gasification method according to claim 3 of the present application, by using mineral powders such as limestone and straw, oxide powders such as blast furnace slag powder, refractory powder, and various cement powders as a preparation agent, Adjustment of the amount of ash can be suitably performed.

It is a schematic block diagram of the coal gasifier to which this invention is applied. It is a graph which shows the relationship between the ash content (horizontal axis) of coal in the coal gasification furnace of a coal gasifier, and the total amount of heat loss (vertical axis).

An embodiment of the present invention will be described with reference to FIGS. 1 and 2.
FIG. 1 shows a general coal gasifier 100 shown as the present embodiment, which transports pulverized coal (coal) from a line (not shown) and uses a line 1 to form a gasifying agent (oxygen-containing gas or the like). ) Is injected into a pressurized gasification furnace 3 having a temperature higher than that of the burner 2 to be partially oxidized, and the generated gas G generated in the gasification furnace 3 is discharged from the upper opening 3A.
Above the upper opening 3A of the gasification furnace 3, hydrogen is introduced into the gasification gas generated in the gasification furnace 3, and gas, oil, and char are generated by hydrogenation pyrolysis (not shown). A reforming furnace is connected continuously.

Further, along with the partial oxidation in the gasification furnace 3, the ash content in the coal becomes a slag as a by-product and is slag-coated on the inner wall of the gasification furnace 3 (indicated by a symbol S), and a part of the molten slag S1 Will be discharged.
That is, the gasification furnace 3 is for discharging and dropping molten slag S1 formed therein via a slag tap discharge hole 3B provided in a lower portion thereof, and from the slag tap discharge hole 3B. The discharged molten slag S <b> 1 is cooled while dropping the slag cooling unit 4, and then stored in the slag granulating unit 5.
The slag water granulating unit 5 stores slag cooling water 6 therein, and after the molten slag S1 is granulated and rapidly cooled to form the granulated slag S2, it is discharged from the lower slag discharge hole 5A. .

A connecting pipe 8 having a valve 7 is connected to the slag discharge hole 5A located at the lower part of the slag water granulating unit 5, and the granulated slag S2 discharged from the slag granulating unit 5 through the connecting pipe 8. Is sent to the slag lock hopper 10.
In this slag lock hopper 10, the granulated slag S2 is stored for a certain period of time and slag settled, and after a certain period of time, the granulated slag S2 is removed from the system via the connecting pipe 12 having the valve 11. I try to take it out.

Next, optimization of the slag coating S formed on the inner wall of the gasification furnace 3 will be described.
In the coal gasifier 100 according to the present invention, when gasifying low ash coal with insufficient ash as raw coal, the slag coating S formed on the inner wall of the gasification furnace 3 is set to an appropriate amount. Therefore, a preparation agent is added to the raw coal used as a raw material for coal to adjust the ash content of the coal.

The ratio of the ash content adjusted here will be described with reference to FIG.
The graph of FIG. 2 shows the relationship between the ash content (horizontal axis) of coal supplied to the 2000 t / d gasifier 3 and the total heat loss (vertical axis). Is a graph showing the amount of ash removal heat that flows out as molten slag S1 depending on the amount of ash, “Δ” is a graph showing the amount of heat removed from the gasification furnace 3 according to the amount of ash, and “◯” is the above-mentioned It is a graph which shows the total heat loss which shows the sum total of "(square)" and "(triangle | delta)".

And, as can be seen with reference to the graph showing the total heat loss of “◯”, in this gasification furnace 3, the (optimum) ash content that minimizes the total heat loss is adjusted to 8 wt%, The total heat loss at that time is 6.01 Gcal / h. In addition, when the ash content is 6 to 10 wt%, the heat removal amount is within + 1% (less than 6.09 Gcal / h) compared to the minimum total heat loss, and when the ash content is 2 to 19 wt%, Compared to the minimum total heat loss, the total heat loss is within + 20% (less than 7.10 Gcal / h).
From the above, the coal ash content is adjusted to 2 to 19 wt% (indicated by range a in FIG. 2), preferably 6 to 10 wt% (indicated by range b in FIG. 2), and most preferably adjusted to 8 wt%. Thus, the total heat loss can be suppressed.

  When gasifying low ash coal with insufficient ash as raw coal, the preparation agent is added to the raw coal so that the ash content of the coal is 2 to 19 wt% (preferably 6 to 10 wt%). As the preparation agent, minerals (limestone, cinnabar, granite, etc.) and oxide powders (blast furnace slag powder, refractory powder, various cement powders, etc.) can be used.

  Here, it shows to the following (1)-(3) about an example of the adjustment method of the raw material in the coal gasification method in the coal gasification apparatus which concerns on this embodiment.

(1) SiO ₂ , CaO, Fe ₂ O ₃ , Al ₂ O ₃ , MnO, MgO, TiO ₂ , P ₂ O ₅ , SO ₃ , K ₂ O, Na ₂ O, and the remainder is ignition loss (ig 2. Prepare raw coal with an ash composition of Loss) and measure its ash content.

(2) Next, when the ratio of the ash content of the raw coal is not an appropriate value and the slag coating S formed on the inner wall of the gasification furnace 3 may be insufficient, the ash content is 2 to 19 wt% ( A preparation agent is added to raw coal so that it may become 6-10 wt% preferably.

(3) Finally, the raw coal and the preparation agent are mixed. For example, when the raw coal is conveyed while being measured on a conveyor scale or the like, the preparation agent is mixed at a constant weight ratio in accordance with the flow rate per hour (kg / h). Thereafter, the raw coal and the preparation agent are well mixed using a solid mixer, an air current conveyance or the like. As a result, coal with an ash content of 2 to 19 wt% is generated.

〔Example〕
Hereinafter, an example of the coal gasification method in the coal gasifier according to the present embodiment will be specifically described.
First, when the raw coal to Roiyan charcoal used herein, the ash composition and its ash content, for example, a SiO ₂ 16.47wt%, 12.16wt% of CaO, 7.71wt% of _Fe 2 _{O 3,} al ₂ O ₃ and 11.21wt%, MnO and 0.09 wt%, MgO and 11.1 wt%, the TiO _{2 0.65wt%, 0.044wt%} of P 2 _{O 5,} 18.252wt% of SO _3, K ₂ O is 0.53 wt%, Na ₂ O is 7.18 wt%, and ig. Loss is 14.604 wt% (all are DRY). This raw coal has an ash content of 1.7 wt%, and if it is gasified as it is, the total heat loss increases. Therefore, as shown in the above (2) and (3), a preparation agent is added, and the ash content is 8 wt%. The total heat loss was reduced by increasing it to%.

In this example, the basicity of the raw coal is about 0.738. The coal gasification furnace was operated at a pressure of 2.5 MPaG and a temperature of 1550 ° C. by charging partially oxidized coal 650 kg / h, oxygen 300 Nm ³ / h, steam 65 kg / h, and reforming coal quantity 200 kg / h. However, the gas generation amount was about 1400 Nm ³ / h and char 70 kg / h. The amount of slag generated when such raw coal was used was about 35 kg / h, most of which was cylindrical fibrous slag having a diameter of 0.5 or less.
Further, as described above, by adding the preparation agent, the ash content of the raw coal, which was 1.7 wt%, is increased to 8 wt%, so that sufficient slag coating S is formed on the inner wall of the gasification furnace 3. It was confirmed that the temperature of the gasification furnace 3 was kept constant without increasing the supply amount of oxygen gas.

  As described above in detail, according to the coal gasification method according to the present embodiment of the present invention, the preparation agent is added so that the ash content of the raw material coal is 2 to 19 wt%, preferably 6 to 10 wt%. Therefore, even when low ash coal with insufficient ash content is used as raw coal for gasification, the slag coating S in the gasification furnace 3 is maintained at an appropriate amount, and the slag coating S is insufficient or excessive. The temperature drop in the furnace caused by the above can be prevented. That is, according to the coal gasification method according to this embodiment of the present invention, by a simple method of adding a preparation agent so that the ash content of coal is 2 to 19 wt% (preferably 6 to 10 wt%), Even when gasifying low ash coal with insufficient ash content as raw coal, the optimal slag coating S is performed in the furnace, so that the temperature in the gasification furnace can be suitably maintained, and efficient coal gas. The operation of the converter can be performed.

  In addition, in the said embodiment, although the preparation agent is added so that the amount of ash of coal may be 2-19 wt%, in addition to this, in order to keep the generation rate of fibrous slag low, it is slag. Component adjustment to increase the basicity of may be performed.

  Moreover, in the said embodiment, although the two-chamber two-stage furnace which consists of the gasification furnace 3 and a reforming furnace was used, it is not limited to this, For example, in one furnace, gasification gas is produced | generated, and hydropyrolysis In a coal gasification apparatus having a gasification furnace that performs both of the above and the like, in order to perform optimum slag coating, a preparation agent may be added so that the ash content of coal becomes 2 to 19 wt%.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the concrete structure is not restricted to this embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

  The present invention relates to a coal gasification method in a coal gasification apparatus having a gasification furnace for partially oxidizing and gasifying coal.

3 Gasifier 100 Coal gasifier S Slag coating

Claims (3)

A coal gasification method in a coal gasifier having a gasification furnace for partially oxidizing and gasifying coal,
A coal gasification method, wherein a preparation agent is added to raw coal as a raw material of the coal so that an ash content of the coal is 2 to 19 wt%.   The coal gasification method according to claim 1, wherein a preparation agent is added so that the ash content of the coal is preferably 6 to 10 wt%.   3. The coal gasification method according to claim 1, wherein minerals such as limestone and cinnabar, and oxide powders such as blast furnace slag powder, refractory powder, and various cement powders are used as the preparation agent. .

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