A special gasification raw material, its production process and application

Abstract

The application discloses a special gasification raw material and a production process and application thereof, and belongs to the technical field of metallurgy and coal chemical industry. The special gasification raw material comprises slime and power coal, and the slime accounts for 5wt%-40wt% of the total weight of the slime and the power coal. The new special gasification raw material prepared by taking the slime and the power coal as raw materials can replace traditional coal into a fixed bed gasification furnace for gasification to produce gas, can realize recycling of the slime, and can widen the selection channel of raw materials for coal gasification technology, and the high-concentration crude coal gas produced by the application can be widely used as a basic raw material for chemical fertilizer and chemical industry, and therefore has great economic value.

Description

Technical Field

[0001] This application relates to a special gasification feedstock, its production process, and its application, belonging to the fields of metallurgy and coal chemical technology. Background Technology

[0002] With the rapid development of both the depth and breadth of coal processing, the output of coal slime has also shown a significant upward trend. Data shows that in 2021, my country's coal slime output increased from 168.61 million tons in 2014 to 209.61 million tons. It is expected that as overall output maintains a relatively stable growth trend in the future, coal slime production will also increase accordingly.

[0003] However, in terms of current utilization, coal slime in my country is mainly used for combustion, creating some competition with thermal coal, but it is generally at a disadvantage. Its market price is greatly affected by the demand from the thermal coal and power generation markets. Meanwhile, due to its relatively low calorific value and high transportation costs, and given the continued oversupply in the coal market, although the industry's utilization rate has been increasing, it remains at a low level overall. Therefore, the comprehensive utilization of coal slime in my country is an urgent issue that needs to be addressed.

[0004] At present, coal gasification technologies at home and abroad are mainly divided into three categories: The first category is fixed bed gasification technology, including fixed bed atmospheric intermittent gasification (represented by UGI gasification technology) and fixed bed pressurized gasification (mainly Lurgi and improved dry ash-discharge crushed coal pressurized gasification process and BGL crushed coal slag gasification process); The second category is fluidized bed gasification technology, mainly including (1) fluidized bed atmospheric gasification, represented by U-gas gasification process and ash melting agglomeration gasification process; (2) fluidized bed pressurized gasification, represented by high temperature Winkler gasification process and KBR-TRIG gasification process. The third category is fluidized bed pressurized gasification: it is divided into coal-water slurry pressurized gasification technology and pulverized dry coal pressurized gasification technology. Its gasification process is further divided into three categories: quench process, waste boiler process, and semi-waste boiler process. Among them, coal-water slurry gasification technology is represented by East China University of Science and Technology's multi-nozzle gasification technology in China and by GE gasification abroad. Coal-water slurry gasification technology mostly adopts the quench process. In recent years, some projects have begun to adopt the semi-waste boiler process of East China University of Science and Technology and GE. The waste boiler process is represented by SHELL process technology. The quench process of pulverized dry coal gasification technology is represented internationally by Colin CCG, GSP and SHELL downflow water quench gasification processes, and domestically by Ningxia Coal Mine Gasification and HT-L pulverized coal pressurized gasification technology.

[0005] The raw materials used in the above-mentioned coal gasification technologies are mainly lignite, bituminous coal, and anthracite. The cost of coal gasification raw materials is high, and there are no large-scale cases of recycling coal slime to produce special gasification raw materials. Summary of the Invention

[0006] To address the aforementioned issues, a special gasification feedstock, its production process, and its applications are provided. Using coal slime and thermal coal as raw materials, the novel special gasification feedstock can replace traditional coal types in fixed-bed gasifiers for gasification. This not only enables the recycling of coal slime but also broadens the selection channels for raw materials used in coal gasification technology. The high-concentration crude coal gas produced can be widely used as a basic raw material for fertilizers and chemicals, thus possessing significant economic value.

[0007] According to one aspect of this application, a special gasification feedstock is provided, comprising coal slime and thermal coal, wherein the coal slime accounts for 5 wt% to 40 wt% of the total weight of all coal slime and thermal coal.

[0008] Coal slime generally refers to the semi-solid material formed by the presence of water in pulverized coal. It originates from the tailings of flotation in coking coal preparation plants and the coal-water mixture. Before the 1980s, coal slime was a primary source of fuel for ordinary people. To facilitate storage and use, coal slime was typically mixed with a small amount of loess to make coal bricks and honeycomb briquettes.

[0009] This application uses coal slime as a component of a special gasification feedstock, which enables the comprehensive utilization of coal slime, expands its application pathways, and reduces the cost of coal slime recycling and treatment. The special gasification feedstock prepared by combining this coal slime with thermal coal has good compatibility between the two feedstocks, resulting in a uniform special gasification feedstock that is conducive to gasification. Moreover, the production cost is low, making it suitable for large-scale production and use. At the same time, it improves the thermal strength of the special gasification feedstock.

[0010] Optionally, the coal slime has a moisture content of 12wt%-15wt%, an ash content of 20wt%-32wt%, and a calorific value of 12.5-20MJ / kg; preferably, the coal slime has a volatile matter content of 15wt%-25wt%.

[0011] The moisture content in the coal slime significantly affects the blending effect between the coal slime and the thermal coal, and also greatly influences the generation of special gasification feedstock. Within the aforementioned range, the lower the moisture content, the better. If the moisture content is too high, the coal slime will have low utilization value, making it difficult to achieve industrial application. The ash content affects the calorific value of the special gasification feedstock. If the ash content is too high, the calorific value will be low, resulting in low utilization value. Therefore, within this range, the lower the ash content, the better, as lower ash content leads to higher calorific value and higher utilization value. The calorific value is an important performance indicator reflecting the special gasification feedstock. A high calorific value indicates high utilization rate and high efficiency, while a low calorific value indicates low utilization rate and low efficiency. Volatile matter is generally composed of H2, CO, CH4, etc. Its content is the primary indicator for judging the ignition characteristics of the special gasification feedstock. The higher the content, the easier it is to ignite; the lower the content, the more difficult it is to ignite. The lower the moisture content, ash content, and volatile matter content, the better. However, too low a content will cause a sharp increase in process costs and make the process difficult to implement. Therefore, within the above range, it is possible to meet the requirements of mass production in industry.

[0012] Optionally, the particle size of the coal slime is 150-300 mesh;

[0013] Preferably, the proportion of coal slime with a particle size of less than 200 mesh is 70-90% of the total coal slime.

[0014] The particle size of the coal slime mentioned above can ensure thorough mixing with the thermal coal, increase the contact area with the thermal coal, and facilitate the generation of special gasification feedstock.

[0015] Optionally, the calorific value of the thermal coal is Qb5000-Qb7000. Thermal coal with this calorific value, when blended with coal slime, can be smelted into a stable and high-quality special gasification feedstock. Excessively high calorific value will increase the price of thermal coal and smelting costs, which is detrimental to industrial production; conversely, too low a calorific value will prevent the coal from being blended with coal slime to produce a suitable special gasification feedstock.

[0016] Optionally, the volatile matter content of the thermal coal is 25-32 wt%, the ash content is 5-25 wt%, the moisture content is 3.5-8.5 wt%, the ash melting point is 1100-1500℃, and the sulfur content is less than 2.5%.

[0017] Volatile matter is the primary indicator for determining the ignition characteristics of thermal coal. Higher volatile matter content makes ignition easier, while lower content makes ignition more difficult. Ash content affects calorific value; excessive ash content results in low calorific value and low utilization value, while lower ash content leads to higher calorific value and higher utilization value. Moisture content significantly impacts the blending effect of coal slime and thermal coal, and also greatly affects the formation of specialized gasification feedstock; lower moisture content is better. However, when coal slime and thermal coal are blended for gasification coke production below their ash melting point, the ash melting point is not a controlling indicator. The temperature at the center of coke cake maturation is 600-700℃, which does not reach the ash melting point. Therefore, in the smelting of blended coal slime and thermal coal, specialized gasification feedstock is formed, rather than ash.

[0018] Sulfur is a harmful impurity that increases the corrosiveness of equipment. Therefore, limiting the sulfur content to less than 2.5% can reduce the impact of this special gasification feedstock on the equipment during production and use. In addition, it can also reduce the content of impurity gas H2S generated by this special gasification feedstock, thereby further improving the purity of H2 and CO generated by this special gasification feedstock.

[0019] Optionally, the thermal strength of the special gasification feedstock is 47-53, and the thermal reactivity is 31.5-35.

[0020] According to another aspect of this application, a process for producing the special gasification feedstock described in any of the above claims is provided, comprising the following steps:

[0021] (1) The coal slime and power coal are mixed to obtain mixed coal;

[0022] (2) The mixed coal is made into coke cake, the coke cake is smelted and cooled to obtain the special gasification raw material.

[0023] Optionally, in the smelting of step (2), the core temperature of the coke cake is 600-700℃, the temperature of the vertical flue is 1100-1150℃, and the smelting time is 15-20h.

[0024] The mixed coal is tamped into coal cakes using a tamping machine, and then pushed into the coke oven carbonization chamber by a coal pusher for smelting, producing a special gasification feedstock, which is semi-coke produced by coke oven smelting. The vertical flue temperature refers to the temperature of the coke oven combustion chamber, and the maturation center temperature of the coke cake refers to the center temperature of the special gasification feedstock in the carbonization chamber. The size of the coke cake is determined by the size of the carbonization chamber and can be set to 14900mm*5200mm*470mm.

[0025] Optionally, in the smelting process of step (2), a dry component of coke oven gas is formed, which includes H2: 50%-55%, CH4: 22%-27%, CO: 10%-12%, C2H4: 2%-4%, CO2: 1.5%-5%, O2: 0.3%-0.8%, N2: 3%-7%, H2S: 1-1.4%, and NH3: 0.25-0.35%.

[0026] According to another aspect of this application, the application of the special gasification feedstock described in any of the preceding claims is provided, said special gasification feedstock being used to produce crude coal gas.

[0027] Optionally, the step of using the special gasification feedstock to produce crude coal gas is as follows: placing the special gasification feedstock in a fixed-bed gasifier and gasifying it at 1150℃-1350℃ and atmospheric pressure to obtain the crude coal gas.

[0028] Preferably, the volume percentage of H2 and CO in the crude coal gas on a wet basis is 30-40%.

[0029] More preferably, the dry basis volume percentage of H2 and CO in the crude gas is 75-89%.

[0030] The above-mentioned special gasification feedstock, when gasified at high temperature and normal pressure, can increase the yield of H2 and CO in crude coal gas. At this temperature of 1150℃-1350℃, the following four reactions will occur:

[0031] 1. Water vapor reformation reaction: C + H₂O = CO + H₂ - 131 kJ / mol

[0032] 2. Water-gas shift reaction: CO + H₂O = CO₂ + H₂ + 42 kJ / mol

[0033] 3. Partial oxidation reaction: C + 0.5O₂ = CO + 111kJ / mol

[0034] 4. Reduction reaction: C + CO2 = 2CO - 172 kJ / mol.

[0035] Preferably, the volume percentage of H2 in the crude gas on a wet basis is 13-17%, and the volume percentage of CO on a wet basis is 17-23%.

[0036] Alternatively, the fixed-bed gasifier can be used in an atmospheric pressure intermittent or atmospheric pressure oxygen-enriched manner.

[0037] The beneficial effects of this application include, but are not limited to:

[0038] 1. Based on the special gasification feedstock of this application, coal slime and thermal coal are used as raw materials, replacing traditional coal types for gasification in fixed-bed gasifiers. This broadens the raw material selection channels for coal gasifiers and creates a new gasification pathway, which is of great significance and has huge economic value and can be widely applied.

[0039] 2. According to the special gasification feedstock of this application, high-concentration effective gases, H2 and CO, can be produced after gasification. These gases can be used as basic raw materials for fertilizers and chemicals, thereby expanding the application range of the special gasification feedstock and reducing the production cost of basic raw materials for fertilizers and chemicals.

[0040] 3. The coke oven gas dry component produced during the smelting of the special gasification feedstock of this application can be recycled and reused, for example, as industrial fuel, or for coke oven gas to produce methanol, LNG through low-temperature separation, coke oven gas to produce hydrogen and co-produce pipeline natural gas (PNG), etc., which can make full use of coal slime and power coal resources and realize the recycling of resources. Attached Figure Description

[0041] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0042] Figure 1 This is a schematic diagram of the process flow involved in Embodiment 1 of this application.

[0043] Figure 2 This is a photograph of "blended coal blocks burning in a muffle furnace" as described in Embodiment 1 of this application. Detailed Implementation

[0044] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0045] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0046] Example 1

[0047] This embodiment relates to a special gasification feedstock and its production process. The special gasification feedstock consists of coal slime and thermal coal, wherein the coal slime accounts for 20 wt% of the total weight of all coal slime and thermal coal. The coal slime has a moisture content of 12.9 wt%, an ash content of 20 wt%, a calorific value of 20 MJ / kg, a volatile matter content of 17 wt%, and a sulfur content of 0.75%. The particle size of the coal slime is 150-300 mesh, of which coal slime with a particle size of less than 200 mesh accounts for 80% of the total coal slime. The thermal coal has a calorific value of Qb5000, a volatile matter content of 25 wt%, an ash content of 17 wt%, a moisture content of 8.5 wt%, an ash melting point of 1420℃, and a sulfur content of 0.9%.

[0048] refer to Figure 1 The production process of the above-mentioned special gasification feedstock includes the following steps:

[0049] (1) Mix coal slime and power coal to obtain mixed coal;

[0050] (2) The mixed coal is made into coke cakes with dimensions of 14900mm*5200mm*470mm, as shown in the reference. Figure 2 The coke cake is smelted, and the core temperature of the coke cake during smelting is 700°C, the temperature of the flue is 1150°C, the smelting time is 18 hours, and the special gasification raw material is obtained after cooling. The dry components of coke oven gas generated during the smelting process are collected.

[0051] Example 2

[0052] This embodiment relates to a special gasification feedstock and its production process. The special gasification feedstock consists of coal slime and thermal coal, wherein the coal slime accounts for 5 wt% of the total weight of all coal slime and thermal coal. The coal slime has a moisture content of 15 wt%, an ash content of 32 wt%, a calorific value of 20 MJ / kg, a volatile matter content of 15 wt%, and a sulfur content of 0.75%. The particle size of the coal slime is 150-300 mesh, of which the proportion of coal slime with a particle size of less than 200 mesh is 70%. The thermal coal has a calorific value of Qb5000, a volatile matter content of 25 wt%, an ash content of 25 wt%, a moisture content of 8.5 wt%, an ash melting point of 1500℃, and a sulfur content of 0.9%.

[0053] The production process of the above-mentioned special gasification feedstock includes the following steps:

[0054] (1) Mix coal slime and power coal to obtain mixed coal;

[0055] (2) The mixed coal is made into coke cakes with a size of 14900mm*5200mm*470mm. The coke cakes are smelted. The core temperature of the coke cakes during smelting is 600℃, the temperature of the vertical flue is 1100℃, and the smelting time is 20h. After cooling, the special gasification raw material is obtained, and the dry components of coke oven gas generated during the smelting process are collected.

[0056] Example 3

[0057] This embodiment relates to a special gasification feedstock and its production process. The special gasification feedstock consists of coal slime and thermal coal, wherein the coal slime accounts for 40 wt% of the total weight of all coal slime and thermal coal. The coal slime has a moisture content of 12 wt%, an ash content of 25 wt%, a calorific value of 12.5 MJ / kg, a volatile matter content of 25 wt%, and a sulfur content of 0.75%. The particle size of the coal slime is 150-300 mesh, of which the proportion of coal slime with a particle size of less than 200 mesh is 90%. The thermal coal has a calorific value of Qb7000, a volatile matter content of 32 wt%, an ash content of 5 wt%, a moisture content of 3.5 wt%, an ash melting point of 1100℃, and a sulfur content of 0.62%.

[0058] The production process of the above-mentioned special gasification feedstock includes the following steps:

[0059] (1) Mix coal slime and power coal to obtain mixed coal;

[0060] (2) The mixed coal is made into coke cakes with a size of 14900mm*5200mm*470mm. The coke cakes are smelted. During the smelting, the core temperature of the coke cake is 700℃, the temperature of the vertical flue is 1150℃, and the smelting time is 15h. After cooling, the special gasification raw material is obtained, and the dry components of coke oven gas generated during the smelting process are collected.

[0061] Example 4

[0062] The difference between this embodiment and Embodiment 1 is that the moisture content of the coal slime is 20 wt%, while the other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0063] Example 5

[0064] The difference between this embodiment and Embodiment 1 is that the ash content of the coal slime is 28 wt%, while the other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0065] Example 6

[0066] The difference between this embodiment and Embodiment 1 is that the calorific value of the coal slime is 10 MJ / kg, while the other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0067] Example 7

[0068] The difference between this embodiment and Embodiment 1 is that the volatile matter content of the coal slime is 28 wt%, while the other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0069] Example 8

[0070] The difference between this embodiment and Embodiment 1 is that the particle size of the coal slime is 150-300 mesh, of which the proportion of coal slime with a particle size of less than 200 mesh is 20% of the total coal slime. The other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0071] Example 9

[0072] The difference between this embodiment and Embodiment 1 is that the calorific value of the thermal coal is Qb4500, while the other conditions are the same as in Embodiment 1. Special gasification feedstock is obtained, and the dry components of coke oven gas generated during the smelting process are collected.

[0073] Example 10

[0074] The difference between this embodiment and Embodiment 1 is that the volatile matter content of the thermal coal is 35 wt%, while the other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0075] Example 11

[0076] The difference between this embodiment and Embodiment 1 is that the ash content of the thermal coal is 30 wt%, while the other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0077] Example 12

[0078] The difference between this embodiment and Embodiment 1 is that the moisture content of the power coal is 10 wt%, while the other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0079] Example 13

[0080] The difference between this embodiment and Embodiment 1 is that the ash melting point of the thermal coal is 1550℃, while the other conditions are the same as in Embodiment 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0081] Comparative Example 1

[0082] The difference between this comparative example and Example 1 is that the coal slime accounts for 2 wt% of the total weight of all coal slime and power coal, while the other conditions are the same as in Example 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0083] Comparative Example 2

[0084] The difference between this comparative example and Example 1 is that the coal slime accounts for 50 wt% of the total weight of all coal slime and power coal, while the other conditions are the same as in Example 1, resulting in a special gasification feedstock, and the dry components of coke oven gas generated during the smelting process are collected.

[0085] Test Example 1

[0086] The performance of the special gasification feedstocks obtained in the above embodiments and comparative examples was analyzed, as shown in Table 1 below.

[0087] Table 1

[0088]

[0089]

[0090] According to the data in Table 1, as the moisture content, ash content, calorific value, volatile matter content, and particle size of coal slime increase, and the calorific value of thermal coal decreases while the volatile matter content, ash content, moisture content, and ash melting point increase, the properties of special gasification feedstock, such as the caking index G value, the plastic layer index Y value / mm, thermal strength, and thermal reactivity, gradually decrease.

[0091] Test Example 2

[0092] The dry components of coke oven gas collected in the above embodiments and comparative examples were analyzed. The specific results are shown in Table 2 below. All values ​​in Table 2 are volume percentages.

[0093] Table 2

[0094]

[0095] According to the data in Table 2, as the moisture content, ash content, calorific value, volatile matter content, and particle size of coal slime increase, and the calorific value of thermal coal decreases while the volatile matter content, ash content, moisture content, and ash melting point increase, the H2 and CO contents in the dry components of coke oven gas show a decreasing trend.

[0096] Test Example 3

[0097] The special gasification feedstocks obtained in the above embodiments and comparative examples were placed in a fixed-bed gasifier and gasified at 1150°C and atmospheric pressure to obtain crude coal gas. The wet-based components of the crude coal gas were analyzed, and the results are shown in Table 3 below. All values ​​in Table 3 are volume percentages.

[0098] Table 3

[0099]

[0100] According to the data in Table 3, as the moisture content, ash content, calorific value, volatile matter content, and particle size of coal slime increase, and the calorific value of thermal coal decreases while the volatile matter content, ash content, moisture content, and ash melting point increase, the effective gas content of H2 and CO in the dry components of wet coal gas from a fixed-bed gasifier shows a decreasing trend.

[0101] Test Example 4

[0102] The special gasification feedstock obtained in Example 1 was placed in a fixed-bed gasifier and gasified at 1350°C and atmospheric pressure to obtain crude coal gas. The composition of the crude coal gas was analyzed, as shown in Table 4 below. All values ​​in Table 4 are volume percentages. As can be seen from Table 4, with increasing temperature, the effective gas CO+H2 content increases, while the CO2 content decreases.

[0103] Table 4

[0104]

[0105] The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principles of this application should be included within the scope of protection of this application.

Claims

1. A special gasification feedstock, characterized in that, It includes coal slime and thermal coal, wherein the coal slime accounts for 5 wt% to 40 wt% of the total weight of all coal slime and thermal coal; The coal slime has a moisture content of 12wt%-15wt%, an ash content of 20wt%-32wt%, a calorific value of 12.5-20MJ / kg, and a volatile matter content of 15wt%-25wt%. The thermal coal has a calorific value of Qb5000-Qb7000, a volatile matter content of 25-32 wt%, an ash content of 5-25 wt%, a moisture content of 3.5-8.5 wt%, an ash melting point of 1100-1500℃, and a sulfur content of less than 2.5%.

2. The special gasification feedstock according to claim 1, characterized in that, The particle size of the coal slime is 150-300 mesh.

3. The special gasification feedstock according to claim 1, characterized in that, Coal slime with a particle size of less than 200 mesh accounts for 70-90% of all coal slime.

4. The production process of the special gasification feedstock according to any one of claims 1-3, characterized in that, Includes the following steps: (1) The coal slime and power coal are mixed to obtain mixed coal; (2) The mixed coal is made into coal cakes, the coal cakes are smelted and cooled to obtain the special gasification feedstock; In step (2), the core temperature of the coke cake is 600-700℃, the temperature of the vertical flue is 1100-1150℃, and the smelting time is 15-20h. In step (2), the coke oven gas dry components are formed, which include H2: 50%-55%, CH4: 22%-27%, CO: 10%-12%, C2H4: 2%-4%, CO2: 1.5%-5%, O2: 0.3%-0.8%, N2: 3%-7%, H2S: 1-1.4%, and NH3: 0.25-0.35%.

5. The application of the special gasification feedstock according to any one of claims 1-3, characterized in that, The special gasification feedstock is used to produce crude coal gas.

6. The application according to claim 5, characterized in that, The steps for using the special gasification feedstock to produce crude coal gas are as follows: the special gasification feedstock is placed in a fixed-bed gasifier and gasified at 1150℃-1350℃ and atmospheric pressure to obtain the crude coal gas.

7. The application according to claim 6, characterized in that, The volume percentages of H2 and CO in the crude coal gas on a wet basis are 30-40%.

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