阅读说明：本技术 一种水煤浆制合成气的方法 (Method for preparing synthesis gas from coal water slurry ) 是由 彭绪亚 俞天明 陈锋江 吕彬峰 邱一鑫 李荣辉 于 2019-12-03 设计创作，主要内容包括：本发明公开一种水煤浆制合成气的方法,将低阶煤或者提质煤通过包括破碎和研磨步骤制备得到水煤浆,所述水煤浆在无氧或微氧条件下,加热至800-1300℃,制备得到包含CO和H<Sub>2</Sub>的合成气。本发明的方法,低阶煤通过包括破碎和研磨步骤制备得到水煤浆,然后在无氧或者微氧条件下气化还原,制备得到包含CO和H<Sub>2</Sub>的合成气,所制备合成气中的杂质少,质量高,充分有效地利用了低阶煤中的煤物质,符合国家煤炭综合利用方向。(The invention discloses a method for preparing synthesis gas from coal water slurry, which comprises the steps of crushing and grinding low-rank coal or upgraded coal to obtain the coal water slurry, heating the coal water slurry to 800-1300 ℃ under the condition of no oxygen or micro oxygen to obtain the coal water slurry containing CO and H 2 The synthesis gas of (2). According to the method, the low-rank coal is prepared into the coal water slurry through crushing and grinding steps, and then the coal water slurry is gasified and reduced under the anaerobic or micro-aerobic condition to prepare the coal water slurry containing CO and H 2 The synthetic gas prepared by the method has less impurities and high quality, fully and effectively utilizes coal substances in low-rank coal, and accords with the national comprehensive utilization direction of coal.)

1. The method for preparing the synthesis gas from the coal water slurry is characterized in that the coal water slurry is prepared from low-rank coal by crushing and grinding, and the coal water slurry is heated to 800-1300 ℃ under the anaerobic or micro-aerobic condition to prepare the synthesis gas containing CO and H₂The synthesis gas of (2).

2. The method according to claim 1, wherein the coal-water slurry further comprises upgraded coal, and the upgraded coal is low-rank coal prepared by a gasification reduction process.

3. The method according to claim 1, wherein the low-rank coal is subjected to a pulverization process such that the particle size of the low-rank coal is between 100 mesh and 300 mesh.

4. The method of claim 2 wherein the low rank coal is subjected to a comminution process such that the upgraded coal has a particle size of from 100 mesh to 300 mesh.

5. The method of claim 1, wherein the coal-water slurry is subjected to a grinding step in which upgraded coal is added so that the coal-water slurry has a slurry yield of not less than 55%.

6. The method as claimed in claim 1, wherein the coal water slurry is reacted with water vapor at a temperature of 800-.

7. A method as claimed in claim 6, characterised in that the resistance wire contains nickel and chromium.

8. The method of claim 1 wherein the coal-water slurry is passed through electrodes to which a voltage in excess of 10KV is applied to charge particles of the coal-water slurry.

9. The method according to claim 1, wherein the coal water slurry is subjected to a grinding step in which wastewater containing organic matter is added so that the slurry yield of the coal water slurry is not less than 55%.

10. The method as claimed in claim 1, wherein steam preheated to 800-.

Technical Field

The invention relates to the technical field of clean utilization of coal substances, in particular to a method for preparing synthesis gas from coal water slurry.

Background

China is a country rich in coal, poor in oil and less in gas, and the coal consumption accounts for more than 60% of the primary energy consumption, so that the energy structure mainly based on coal is difficult to change in a long period of time. From the ascertained coal mine quality, the proportion of low-rank coal in the coal in China is very large, so that the reasonable and efficient utilization of the low-and-medium-rank coal to produce high-quality chemical products is very important. In recent years, the continuous development of technologies such as coal gasification, coal pyrolysis, coal gas purification, coal gas separation and the like makes the clean and efficient utilization of medium-low-grade coal more and more important.

The low-rank coal in China is generally used for pyrolysis gasification to crude coal gas and quality-improved coal, the pyrolysis is generally carried out under the condition of a large amount of oxygen (or air), and a part of low-rank coal is used for supplying heat in the oxygen reaction during pyrolysis and generates a large amount of CO₂. Due to CO₂Can not be combusted, belongs to ineffective gas, and has over high nitrogen content due to aerobic combustion, thereby reducing H in the crude gas₂And CO energy density, so that the calorific value of the crude gas is reduced, and the crude gas produced by pyrolysis has other economic values except for return combustion. And because the synthesis gas prepared from the existing low-rank coal and the upgraded coal is subjected to aerobic pyrolysis, the carbon-hydrogen ratio of the synthesis gas obtained from the low-rank coal and the upgraded coal is low, so that the amount of chemical finished products prepared from the synthesis gas is small and less, the effective coal resources in the low-rank coal are greatly wasted, and the utilization rate of the low-rank coal is low.

Disclosure of Invention

In view of the above, the present invention provides a method for preparing synthesis gas from coal water slurry, which comprises crushing and grinding the coal water slurry, and then performing gasification reduction under oxygen-free or micro-oxygen conditions to obtain a coal water slurry containing CO and H₂The synthetic gas prepared by the method has the advantages of less impurities, high quality and low energy consumption, and fully and effectively utilizes coal substances in low-rank coal.

In order to solve the technical problems, the invention provides the following technical scheme:

a method for preparing synthesis gas from low-rank coal slurry comprises the steps of crushing and grinding to obtain the coal slurry, heating the coal slurry to 800-₂The synthesis gas of (2).

The raw material low-rank coal can be pulverized coal or lump coal, and when the low-rank coal adopts the lump coal, the pulverized coal with smaller granularity can be obtained by crushing and screening the oversize lump coal. The low-rank coal dried by the drying process enters the gasification reduction process for reaction, and for one-step optimization process, a gasification feeding process can be added before the dried low-rank coal enters the gasification reduction process, so that the dried low-rank coal can rapidly enter the gasification reduction process, the surface area of the material is increased, and the gasification reduction reaction can be accelerated.

The drying process removes most of moisture in the low-rank coal to obtain dried low-rank coal and waste gas, and the dried low-rank coal enters a gasification reduction process to react to obtain high-temperature synthesis gas and upgraded coal with a certain temperature.

Wherein, the gasification reduction process is a chemical reaction process for heating the dried low-rank coal under the condition of no oxygen or micro oxygen. The dried low-rank coal enters a gasification reduction process, under the heating of heating media such as flue gas and the like, additives and other substances are not needed to be added in the reaction process, the temperature is generally 350-800 ℃, and the pressure is less than or equal to 30Kpa, a complex chemical reaction process is carried out, so that solid carbon and high-temperature synthesis gas are obtained, wherein the solid carbon is upgraded coal, and the volatile components in the upgraded coal are 8-15 wt%. The high-temperature synthesis gas comprises CO and H₂、CO₂Hydrocarbon, coal tar, naphthalene, halide, dust, sulfur compounds, and the like. Preferably, the coal water slurry also contains upgraded coal, and the upgraded coal is prepared from low-rank coal through a gasification reduction process.

The coal water slurry is prepared by crushing and finely grinding coal substances, and because the raw materials adopted by the invention are preferably low-rank coal powder in waste gas generated in the drying process, more than 95% of the low-rank coal powder in the waste gas can be recovered by a first dust removal process, the granularity of the low-rank coal powder is generally less than 3mm, and the preferred coal powder with the granularity of less than 1mm is used as the raw material for preparing the coal water slurry subsequently, the low-rank coal powder is mixed with waste water and additives, the grinding treatment is not needed, the coal water slurry can be obtained, the process steps are saved, the cost of a coal mill is greatly reduced, and the service life of the coal mill is prolonged. And further, the low-order pulverized coal has the particle size of less than or equal to 50 mu m. Preferably, the low-rank coal is subjected to a crushing process so that the particle size of the low-rank coal is between 100 and 300 meshes. Further, the low-rank coal is subjected to a crushing process, so that the particle size of the upgraded coal is between 100 and 300 meshes. Preferably, the coal water slurry is added with upgraded coal in the grinding step, so that the slurry forming rate of the coal water slurry is not lower than 55%. Further, the weight ratio of the low-rank pulverized coal to the upgraded pulverized coal is 1: (1-5).

According to the specified quality standard of the water-coal-slurry of GB/T18856.1, the quality standard is qualified only if the grain diameter of coal powder particles in the water-coal-slurry is more than 1000 μm and the mass percentage is more than 0.01 percent; generally, in the coal water slurry, the particle size of the coal dust particles is required to be 180-180 μm accounting for 15-18%, 106-180 μm accounting for about 30%, 75-106 μm accounting for 2-5%, and 75 μm or less accounting for about 50%.

Heating to 800-₂O (steam) reaction, namely preparing CO and CO from low-rank coal or upgraded coal₂And H₂The main reaction equation of the water gas of (1) is C + H₂O＝CO+H₂. Because most of volatile components, tar and the like in the low-rank coal dried in the gasification reduction process stage are gasified and removed, the content of coal substances in the obtained upgraded coal is high, and therefore, the impurity gas in the water gas obtained by utilizing the upgraded coal is less. Preferably, the coal water slurry is reacted with water vapor at the temperature of 800-1300 ℃ by heating through a resistance wire under the condition of no oxygen or micro oxygen. Further, the resistance wire contains nickel and chromium. Preferably, the coal-water slurry flows through electrodes to which a voltage in excess of 10KV is applied, so that the particles of the coal-water slurry become charged. Preferably, in the process of preparing the synthesis gas by the coal water slurry, steam preheated to 800-.

The water required by the low-rank coal or the upgraded coal gasification preparation can be obtained from water obtained by drying the low-rank coal, and preferably, the water-coal-slurry is added with waste water containing organic matters in the grinding step, so that the slurry forming rate of the water-coal-slurry is not lower than 55%.

The main impurity gas in the synthesis gas obtained by the method for preparing the synthesis gas from the coal water slurry by utilizing the low-rank coal according to the quality is CO₂、H₂S, COS, and a small amount of dust. Preferably, impurities such as acid-removed gas and a small amount of dust in the water gas are discharged through a purification process to obtain purified synthesis gas.

Based on the technical scheme, the method comprises the steps of crushing and grinding the low-rank coal to obtain the coal water slurry, and then carrying out gasification reduction under the anaerobic or micro-aerobic condition to obtain the coal water slurry containing CO and H₂The synthetic gas prepared by the method has less impurities and high quality, fully and effectively utilizes the coal substances in the low-rank coal, and accords with the national comprehensive utilization direction of coal.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the invention to these embodiments. It will be appreciated by those skilled in the art that the present invention encompasses all alternatives, modifications and equivalents as may be included within the scope of the claims.

In the present invention, the raw materials and equipment used are commercially available or commonly used in the art, unless otherwise specified. The methods in the following examples are conventional in the art unless otherwise specified.

The invention discloses a method for preparing synthesis gas from coal water slurry, which comprises the following process steps;

a method for preparing synthesis gas from low-rank coal slurry comprises the steps of crushing and grinding to obtain the coal slurry, heating the coal slurry to 800-₂The synthesis gas of (2).

The raw material low-rank coal can be pulverized coal or lump coal, and when the low-rank coal adopts the lump coal, the pulverized coal with smaller granularity can be obtained by crushing and screening the oversize lump coal. The pulverized coal is preferably used as a raw material, on one hand, the pulverized coal does not need to be crushed and screened, so that the process steps are saved, the heating area is large during drying, the drying efficiency is high, and on the other hand, the pulverized coal is low in price compared with lump coal. Pulverized coal having a particle size of less than 20mm is preferably used, and pulverized coal having a particle size of less than 6mm is still more preferably used.

The low-rank coal generally has 20-55% of volatile components, about 3-15% of tar, 30-60% of fixed carbon, 10-40% of water and the balance of other impurities such as dust. The low-rank coal has a low degree of coalification, but the low-rank coal having a fixed carbon content of 40% to 60% is preferred.

The drying process can only remove most of the free water in the low-rank coal, but not remove the bound water in the low-rank coal, so that the low-rank coal is treated by the drying process to obtain the dried low-rank coal and waste gas, the dried low-rank coal still contains a certain amount of moisture, and the residual moisture can be gasified to form steam in the subsequent gasification reduction process. If the low-rank coal contains a large amount of moisture, the heat consumption in the gasification reduction reaction process is large, so the technical scheme of the invention firstly treats the low-rank coal through a drying process and removes a part of moisture in the low-rank coal. The drying medium of the drying process can be flue gas or water vapor, and the drying can be divided into direct drying and indirect drying. When flue gas is used as a drying medium, although the drying efficiency of the flue gas in direct contact with low-rank coal is the highest, the volume percentage of oxygen in the drying process environment is strictly controlled to be below an explosion limit when the flue gas is used for drying so as to prevent deflagration, and the efficiency of flue gas indirect drying is not ideal, so that steam drying is preferred for production safety and drying efficiency. The direct drying of the steam can easily cause the steam to be mixed into the low-rank coal, thereby not only causing the consumption of reaction coal resources, but also reducing the drying efficiency, and therefore, the drying mode of indirectly drying the low-rank coal by the steam is adopted to prevent the moisture in the steam from entering the low-rank coal. In addition, if the pressure of the steam is too high in the drying process, the temperature caused by the steam is too high, so that partial volatile components in the low-rank coal can escape out in the drying process, on one hand, the escape of the volatile components can bring potential safety hazards, and on the other hand, the gas yield of a subsequent gasification reduction process can be influenced, therefore, the drying steam pressure is not too high in the drying process, the drying effect can be guaranteed, and the volatile components in the low-rank coal can be prevented from being gasified. Therefore, preferably, the drying process adopts indirect drying by using water vapor, the pressure of the water vapor is 0.3-1.5Mpa, the temperature of the water vapor is 105-250 ℃, the water content in the low-rank coal can be reduced to the maximum extent under the process condition, even the water content in the low-rank coal discharged from a discharge port of the drying process can be reduced to below 7 wt%, most of the water escapes from the low-rank coal along with dust such as coal dust and enters the waste gas generated after drying in the form of the water vapor, and the temperature of the material at the discharge port of the drying process is 50-150 ℃; still further preferably, when the pressure of the water vapor is 0.6-1.2Mpa and the temperature of the water vapor is 120-200 ℃, the water content of the dried low-rank coal is reduced to below 6 wt%, and the temperature of the outlet material of the drying process is 80-130 ℃.

The drying process can be one-stage or multi-stage, because if the water content of the low-rank coal after the first-stage drying process still does not meet the process requirement, multi-stage drying such as secondary drying, tertiary drying and the like can be adopted to continue further drying until the water content of the dried low-rank coal meets the process condition. In addition, the multistage drying process can be arranged in series or in parallel, the drying effect can be enhanced when the multistage drying process is connected in series, and the treatment capacity of the drying process can be increased when the multistage drying process is connected in parallel, so that the design that the multistage drying process is connected in series or in parallel or in series and in parallel can be adjusted according to the actual situation according to the requirement of the actual production process as long as the same technical effect can be achieved, and specifically, for example, when the feeding capacity of the drying process is calculated by low-rank coal of 20-30t/h, a one-stage steam drying process can be adopted; when the feeding amount of the drying process is calculated by a low level of 50-70t/h, a secondary steam drying process can be adopted, so that the method is more economical and reasonable.

The low-rank coal dried by the drying process enters the gasification reduction process to react, and a gasification feeding process can be added before the dried low-rank coal enters the gasification reduction process, so that the dried low-rank coal can rapidly enter the gasification reduction process, the surface area of the material is increased, and the gasification reduction reaction is accelerated.

Wherein, the gasification reduction process is a chemical reaction process for heating the dried low-rank coal under the condition of no oxygen or micro oxygen. The dried low-rank coal enters a gasification reduction process, under the heating of heating media such as flue gas and the like, additives and other substances are not needed to be added in the reaction process, the temperature is generally 350-800 ℃, and the pressure is less than or equal to 30Kpa, a complex chemical reaction process is carried out, so that solid carbon and high-temperature synthesis gas are obtained, wherein the solid carbon is upgraded coal, and the volatile components in the upgraded coal are 8-15 wt%. The high-temperature synthesis gas comprises CO and H₂、CO₂Hydrocarbon, coal tar, naphthalene, halide, dust, sulfur compounds, and the like.

Heating to 800-₂O (steam) reaction, namely preparing CO and CO from low-rank coal or upgraded coal₂And H₂The reaction equation of the water gas of (1) is C + H₂O＝CO+H₂. Because most of volatile components, tar and the like in the low-rank coal dried in the gasification reduction process stage are gasified and removed, the content of coal substances in the obtained upgraded coal is high, and therefore, the impurity gas in the water gas obtained by utilizing the upgraded coal is less. Preferably, the coal water slurry is reacted with water vapor at the temperature of 800-1300 ℃ by heating through a resistance wire under the condition of no oxygen or micro oxygen. Further, the resistance wire contains nickel and chromium. Preferably, the coal-water slurry flows through electrodes to which a voltage in excess of 10KV is applied, so that the particles of the coal-water slurry become charged.

In the actual production process, continuous and uninterrupted heating is generally adopted, so that upgraded coal or low-rank coal in the coal water slurry reacts with steam to prepare synthesis gas uninterruptedly. The water required by the low-rank coal or the upgraded coal gasification preparation can be obtained from water obtained by drying the low-rank coal, and preferably, the water-coal-slurry is added with waste water containing organic matters in the grinding step, so that the slurry forming rate of the water-coal-slurry is not lower than 55%.

The main impurity gas in the synthesis gas obtained by the method for preparing the synthesis gas from the coal water slurry by utilizing the low-rank coal according to the quality is CO₂、H₂S, COS, and a small amount of dust. Preferably, impurities such as acid-removed gas and a small amount of dust in the water gas are discharged through a purification process to obtain purified synthesis gas.

Experimental example 1

A method for preparing synthesis gas from low-rank coal slurry comprises the steps of crushing and grinding to obtain the coal slurry, heating the coal slurry to 800-₂The synthesis gas of (2).

In the embodiment 1, the low-rank coal is pulverized coal with the granularity of less than 20 mm;

in example 1, the rate of formation of the coal water slurry is not less than 55%, specifically 58%, the coal water slurry is sprayed from the top in the gasification furnace, and during the falling process, the coal water slurry is heated to 800-1300 ℃, specifically about 1000 ℃, so that the coal in the coal water slurry reacts with the steam to generate CO and H₂。

Experimental example 2

Experimental example 2 referring to Experimental example 1, except that in the experimental example 2, the coal water slurry is heated by a resistance wire under the condition of no oxygen or micro oxygen, so that the synthesis gas is prepared at the temperature of 800-. Specifically, low-rank coal in the coal water slurry reacts with steam at the temperature of about 1000 ℃ to obtain synthesis gas.

Experimental example 3

Experimental example 3 reference was made to experimental example 1 except that in experimental example 3, the coal-water slurry was passed through electrodes to which a voltage exceeding 10KV was applied, so that particles of the coal-water slurry were charged. Aim at for steam can have enough time to be attached on the low order coal granule and inside the gap when preparing synthetic gas, is favorable to the formation of synthetic gas.

Comparative example 1

A process for preparing synthetic gas from coal-water slurry features that the coal-water slurry with slurry rate of 58% is reacted in gasifying furnace while oxygen or air is introduced to itReacting low-rank coal with steam under the condition of oxygen-containing gas to prepare the low-rank coal containing CO and H₂The synthesis gas of (2).

In comparative example 1, it was necessary to continuously introduce O₂So that part of the low-rank coal in the water-coal-slurry is combusted to release heat, the environmental temperature quickly reaches 800-₂The obtained gas is synthetic gas which mainly comprises CO and CO₂And H₂. By continuously and uninterruptedly introducing O₂And (3) synthesizing gas so that the upgraded coal reacts with the water vapor, the temperature is maintained at 800-1300 ℃, and the synthesis gas is continuously prepared.

TABLE 2 analysis table of composition of syngas produced in test examples 1-3 and comparative example 1^*

Composition of	Experimental example 1	Experimental example 2	Experimental example 3	Comparative example 1
					CH4	37.42	38.03	38.55	0.67
H2	25.03	25.53	25.18	33.40
					CO	23.24	23.15	22.62	43.70
CO2	1.66	1.24	1.28	12.91
					N2	1.40	1.25	1.45	1.08
H2O	10.68	10.26	10.36	10.64
					Others	0.57	0.54	0.56	0.60
Sulfur content	4200ppm	62ppm	31ppm	4500ppm
					H2/CO	1.08	1.10	1.11	0.70

Note: 1. the content is volume percentage content;

2. others include other alkanes and ammonia.

From the results of Table 2, analyzing the composition of the resulting syngas gas, we can obtain that, first, upgraded coal of Experimental examples 1, 2 and 3 was prepared to contain CO and H by reacting with steam under oxygen-free or micro-oxygen conditions₂So that in the synthesis gas, H₂CO, all above 1.0, and the amount of carbon dioxide in the synthesis gas of experimental example 1, experimental example 2 and experimental example 3 was significantly lower than that of comparative example 1. Secondly, we have found unexpectedly that in experimental examples 2 and 3, the sulfur content in the resulting synthesis gas is significantly reduced, whereby the upgraded coal is heated by resistance wires such that the coal-water slurry produces synthesis gas at a temperature of about 1000 ℃, and the coal-water slurry flows through electrodes to which a direct current voltage in excess of 10KV is applied, such that the coal-water slurry particles are charged, both contributing to H₂S is ionized into elemental sulfur, so that the sulfur content is obviously reduced in the prepared synthetic gas.

In summary, the method of the invention, the low-rank coal is prepared into the coal water slurry by the steps of crushing and grinding, and further, the upgraded coal is obtained by gasifying and reducing the low-rank coal, and then the upgraded coal is prepared and prepared to contain CO and H under the condition of no oxygen or micro oxygen₂The synthetic gas prepared by the method has less impurities and high quality, fully and effectively utilizes coal substances in low-rank coal, and accords with the national comprehensive utilization direction of coal.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.