阅读说明：本技术 一种在线修复粉煤气化炉水冷壁固定渣层的方法 (Method for repairing fixed slag layer of water-cooled wall of pulverized coal gasifier on line ) 是由 王贵顺 宋星星 叶莲祥 孙逢玖 罗盼盼 李小兵 于 2020-06-19 设计创作，主要内容包括：本发明公开了一种在线修复粉煤气化炉水冷壁固定渣层的方法,其特征在于：将气化炉原料煤送入粉煤气化炉中进行气化反应,通过控制煤灰中硅铝比不低于2.0且氧化钙含量为8.0-13.0wt％,实现粉煤气化炉水冷壁上渣层的在线修复。本发明通过选用高SiO-(2)、低CaO、低Al-(2)O-(3)的煤种直接作为气化炉原料煤或者作为优选煤与其他原煤混配后作为气化炉原料煤,严格控制煤灰中的硅铝比和氧化钙含量,进而调节高温高压还原性气氛条件下气化炉内液态炉渣的流动性、粘度和表面张力等特性,达到修复水冷壁表面已局部或大面积脱落的渣层,形成具有较大热阻的隔热层,从而对炉体起到保护作用,使得气化炉能够长周期安全稳定运行。(The invention discloses a method for repairing a fixed slag layer of a water-cooled wall of a pulverized coal gasifier on line, which is characterized by comprising the following steps of: the raw material coal of the gasification furnace is sent into a pulverized coal gasification furnace for gasification reaction, and the on-line repair of a slag layer on a water-cooled wall of the pulverized coal gasification furnace is realized by controlling the silica-alumina ratio in the coal ash to be not less than 2.0 and the content of calcium oxide to be 8.0-13.0 wt%. The invention selects high SiO 2 Low CaO and low Al 2 O 3 The coal type is directly used as raw material coal of the gasification furnace or is used as raw material coal of the gasification furnace after being mixed with other raw coal as preferred coal, the silicon-aluminum ratio and the calcium oxide content in the coal ash are strictly controlled, and then the characteristics of liquidity, viscosity, surface tension and the like of liquid slag in the gasification furnace under the high-temperature high-pressure reducing atmosphere condition are adjusted, so that a slag layer which is locally or largely dropped on the surface of a water-cooled wall is repaired, and the formed slag layer is formedThe gasifier has a heat insulation layer with larger thermal resistance, thereby protecting the gasifier body and ensuring the gasifier to run safely and stably for a long period.)

1. A method for repairing a fixed slag layer of a water-cooled wall of a pulverized coal gasifier on line is characterized by comprising the following steps: the raw material coal of the gasification furnace is sent into a pulverized coal gasification furnace for gasification reaction, and the on-line repair of a slag layer on a water-cooled wall of the pulverized coal gasification furnace is realized by controlling the silica-alumina ratio in the coal ash to be not less than 2.0 and the content of calcium oxide to be 8.0-13.0 wt%.

2. The method for repairing the slag layer on the water-cooled wall of the pulverized coal gasification furnace on line according to claim 1, which is characterized in that: the raw material coal of the gasification furnace comprises the following components:

1-2 parts by weight of coal is preferred;

0-3 parts of other raw coal;

limestone powder 0-3.5 wt% of total coal amount of preferred coal and other raw coal;

the silicon-aluminum ratio in the preferable coal is not less than 2.5, and the content of calcium oxide is not more than 10.0 wt%; the other raw coal is coal types other than the preferred coal.

3. The method for repairing the fixed slag layer of the water-cooled wall of the pulverized coal gasification furnace on line according to claim 1 or 2, which is characterized in that: the silicon-aluminum ratio in the coal ash is 2.00-3.00, and the content of calcium oxide is 8.0-13.0 wt%.

4. The method for repairing the fixed slag layer of the water-cooled wall of the pulverized coal gasification furnace on line according to claim 1 or 2, which is characterized in that: the ash melting point of the gasification furnace raw material coal is 1200-1440 ℃.

5. The method for repairing the fixed slag layer of the water-cooled wall of the pulverized coal gasification furnace on line according to claim 1 or 2, which is characterized in that: the gasification furnace is a pressurized entrained-flow bed gasification furnace.

6. The method for repairing the fixed slag layer of the water-cooled wall of the pulverized coal gasification furnace on line according to claim 1 or 2, which is characterized in that: the gasification reaction temperature is 1400-1700 ℃, and the pressure is 2.5-5.0 MPag.

Technical Field

The invention belongs to the technical field of clean production of coal, and relates to a method for repairing a slag layer on line, in particular to a method for repairing a fixed slag layer of a water-cooled wall of a pulverized coal gasifier on line.

Background

At present, a water-cooled wall gasification furnace is taken as an important type of entrained flow gasification technology, and the core idea is 'slag resistance', namely, a large amount of slag generated in the gasification process is attached to the inner wall of the gasification furnace to form a heat insulation layer with larger heat resistance, so that a furnace body is protected. Meanwhile, the solid slag layer can prevent the inner wall of the metal from being eroded by gasified slag, and the gasification device can run for a long period. However, in the actual operation process, after long-period operation, the fixed slag on the furnace wall of the gasification furnace falls off locally or in a large area due to the influence of factors such as uneven thickness, change of operating environment and the like, and particularly, the furnace bottom cone area with a certain inclination angle is formed. In case fixed slag layer drops and can not in time restore the condition on appearing the water-cooling wall surface, the fire-resistant heat preservation of gasifier will destroy immediately, and the furnace inner wall pin burns and melts, leads to the gasifier overtemperature simultaneously, must stop the maintenance immediately.

Disclosure of Invention

In order to solve the technical problem that the long-period operation of the gasification furnace is influenced by the fact that the slag layer on the surface of the water-cooled wall of the gasification furnace drops locally or in a large area during the actual operation of the gasification furnace, the invention aims to provide a method for repairing the fixed slag layer on the water-cooled wall of the pulverized coal gasification furnace on line, which selects high SiO₂Low CaO and low Al₂O₃The coal is directly used as raw material coal of the gasification furnace or is used as gas after being mixed with other raw coal as optimized coalThe silicon-aluminum ratio (SiO) in the raw material coal is strictly controlled by a furnace raw material coal₂With Al₂O₃Mass percentage content ratio) and calcium oxide content, and further adjusting the characteristics of fluidity, viscosity, surface tension and the like of liquid slag in the gasification furnace under the high-temperature high-pressure reducing atmosphere condition, so as to repair a slag layer which is locally or largely dropped on the surface of a water-cooled wall and form a heat insulation layer with larger heat resistance, thereby protecting the furnace body and ensuring that the gasification furnace can safely and stably operate for a long period.

In order to achieve the technical purpose, the invention adopts the following technical scheme:

a method for repairing a fixed slag layer on a water-cooled wall of a pulverized coal gasifier on line is characterized in that raw material coal of the gasifier is fed into the pulverized coal gasifier for gasification reaction, and the on-line repair of the slag layer on the water-cooled wall of the pulverized coal gasifier is realized by controlling the silica-alumina ratio in the coal ash to be not less than 2.0 and the content of calcium oxide to be 8.0-13.0 wt%.

Preferably, the raw material coal of the gasification furnace comprises the following components:

1-2 parts by weight of coal is preferred;

0-3 parts of other raw coal;

limestone powder 0-3.5 wt% of total coal amount of preferred coal and other raw coal;

the silicon-aluminum ratio in the preferable coal is not less than 2.5, and the content of calcium oxide is not more than 10.0 wt%; the other raw coal is coal types other than the preferred coal.

Preferably, the ratio of silicon to aluminum in the coal ash is 2.00-3.00, and the content of calcium oxide is 8.0-13.0 wt%

Preferably, the ash melting point of the gasification furnace raw material coal is 1200-1440 ℃.

Preferably, the gasification furnace is a pressurized entrained-flow gasification furnace.

Preferably, the gasification reaction temperature is 1400-1700 ℃, and the pressure is 2.5-5.0 MPag.

The invention selects high SiO₂Low CaO and low Al₂O₃The coal type is directly used as raw material coal of the gasification furnace or is used as raw material of the gasification furnace after being mixed with other raw coal as optimized coalThe inventor finds that the surface tension of the liquid slag is reduced by strictly controlling the content of calcium oxide in the coal ash under the condition of meeting the liquefaction temperature and the liquidity of the liquid slag in the gasification furnace because the surface tension of calcium oxide in the coal ash component is larger. Based on the above, the inventor unexpectedly finds that the liquid slag can uniformly cover the damaged part of the fixed slag layer on the water-cooled wall of the gasification furnace through the synergistic regulation and control of the liquefaction temperature, the fluidity and the surface tension of the liquid slag, so as to form a heat insulation layer with larger thermal resistance, and achieve the purpose of online repair, thereby protecting the furnace body and ensuring the gasification furnace to be operated safely and stably for a long period.

The invention has the advantages that:

1. the invention can adjust the liquefaction temperature, the fluidity and the surface tension of the liquid slag in the gasification furnace only by selecting and preparing the coal types, does not need to additionally add an auxiliary agent, further does not need to set an auxiliary agent recovery and treatment process, and is simple and efficient.

2. The invention can cooperatively regulate and control the liquefaction temperature, the fluidity and the surface tension of the liquid slag only by selecting and preparing the coal type, can ensure that the liquid slag uniformly covers the damaged part of a fixed slag layer on the water-cooled wall of the gasification furnace to form a heat insulation layer with larger thermal resistance, and achieves the aim of on-line repair, thereby protecting the furnace body, ensuring that the gasification furnace can safely and stably operate for a long period, and avoiding huge economic loss caused by coal gasification as a chemical source to stop and repair the gasification furnace.

3. The invention changes the composition of the raw material coal of the gasification furnace only by selecting and preparing the coal types, so that the prepared raw material coal is suitable for the requirements of the coal gasification device, and the selection range of the coal for coal gasification is wider.

Detailed Description

The invention will now be further described by way of the following examples, which are not intended to limit the scope of the invention in any way. It will be understood by those skilled in the art that equivalent substitutions and corresponding modifications of the technical features of the present disclosure can be made within the scope of the present disclosure.

Example 1

XRF fluorescence spectroscopy analyzed the calcium-silicon-aluminum content of the following coals, such as 187#, 158#, 153#, 152#, 087#, 170#, 125#, 178#, and the results are shown in table 1.

TABLE 1 calcium-silicon-aluminium content of individual coal species

In the above table, the ratio of silica to alumina in 158#, 125#, 153# coals is not less than 2.5 and the content of calcium oxide is not more than 10.0 wt%, which meets the definition of the preferred coals. In this embodiment, the gasification reaction temperature of the AP pulverized coal gasification furnace is 1400-1700 ℃, and the pressure is 2.5-5.0 MPag.

(1) The original formula of the raw material coal of the AP pulverized coal gasification furnace of the company is as follows:

087# 1 parts by weight;

152# 2 parts by weight;

limestone powder 2.5 wt% (total coal amount of 087# and 152 #);

after the operation for 100 days, the slag layer of the water-cooled wall of the gasification furnace suddenly falls off, particularly the slag layer of the water-cooled wall of the bottom cone section suddenly falls off, and the reading of the steam densimeter of the steam-water mixture pipeline of the bottom cone section suddenly changes from the normal value of 740kg/m³Decrease to an abnormal value of 400kg/m³The slag breaker continuously gives an alarm, the oil pressure of the slag breaker suddenly rises from 1.0Mpag to 18.0Mpag, and CO in the crude gas₂From 2.3% of normal value to 1.4% of abnormal value, and CH in the crude gas₄The results are shown in Table 2, which show a series of abnormal phenomena such as an increase from a normal value of 200ppm to 600ppm and a large fluctuation in the steam yield of the water wall;

(2) changing the raw material coal formula of the gasification furnace, mixing the optimized coal and other raw coal to form a new formula:

158# 1 parts by weight;

187# 1 parts by weight;

1.8 wt% of limestone powder (total coal amount of 158# and 187 #);

after the operation for 5 days, gasification production data are obviously changed, the result is shown in table 2, the production is recovered to be normal, the thickness of the slag layer on the water-cooled wall of the gasification furnace is obviously improved, and the fixed slag layer is repaired; the calcium-silicon-aluminum content of the blended coal and the gasification production data before and after use are shown in table 2.

TABLE 2 calcium-silicon-aluminum content and gasification production data for different gasifier feed coal formulations