Preparation method and system of dry mixed coal and dry mixed coal

Abstract

The embodiment of the invention discloses a preparation method and system of dry mixed coal and the dry mixed coal, and the method comprises the following steps: crushing and screening low-rank raw coal to obtain slack coal with the particle size of less than 50mm; drying the slack coal, and removing 10-15% of moisture in the slack coal to obtain dried slack coal; and mixing the dry slack coal with kaolin to obtain the quality-improved and modified dry mixed coal. According to the embodiment of the invention, the boiler slagging contamination phenomenon can be effectively prevented, meanwhile, the calorific value and combustion efficiency of coal are improved at low cost, and pollutant emission is effectively reduced.

Description

Technical Field

[0001] The embodiments of the present invention belong to the field of coal technology, and specifically relate to a method and system for preparing dry mixed coal, and dry mixed coal. Background Art

[0002] Low-rank coal (coal with a long, smoky flame and a low degree of coalification) accounts for a significant portion of coal resources. However, its high alkali metal content and high moisture content severely limit its application in industrial sectors such as coal-fired power plants.

[0003] High-moisture coal reduces combustion efficiency, impacts furnace combustion stability, and reduces the drying output of the pulverizing system. High alkali metal content can lead to slagging and contamination in boilers, reducing heat transfer efficiency, increasing slagging cleaning workload, and raising maintenance costs, seriously impacting the stable operation and economic benefits of coal-fired power plants.

[0004] To address these issues, various methods, such as drying, washing, and chemical modification, have been applied to improve the quality of low-rank coal. However, these technologies focus on improving the quality and overall utilization of the coal itself, while remaining largely ineffective in addressing the problem of boiler slagging and fouling caused by the high alkali metal content during coal combustion. Summary of the Invention

[0005] The technical problem to be solved by the embodiments of the present invention is to address the above-mentioned deficiencies in the prior art and provide a method and system for preparing dry mixed coal, as well as the dry mixed coal obtained by processing using the above-mentioned method or system. The method and system can effectively prevent boiler slagging and contamination, while at the same time improving the calorific value and combustion efficiency of coal at a low cost, and effectively reducing pollutant emissions.

[0006] The technical solution of the embodiment of the present invention to solve the above technical problems is:

[0007] A first aspect of an embodiment of the present invention provides a method for preparing dry mixed coal, comprising:

[0008] Crushing and screening low-rank raw coal to obtain fine coal with a particle size of less than 50 mm;

[0009] Drying the fine coal to remove 10-15% of the moisture in the fine coal to obtain dry fine coal;

[0010] The dry fine coal is mixed with kaolin to obtain the improved and modified dry mixed coal.

[0011] Optional, the coal quality index of low-rank raw coal is: total moisture M t 21~32%, ash content A ar 2~7%, volatile matter V daf The sulfur content is 26-35%. t,d0.1~1.2%, coal calorific value Q net,ar It is 4500~5100kcal.

[0012] Optionally, the blending mass ratio of kaolin is 8 to 12%.

[0013] Optionally, before mixing the dried fine coal with kaolin, the method further includes: crushing the kaolin to less than 10 mm.

[0014] Optionally, when mixing the dry fine coal with kaolin, the dry fine coal is transported by a first belt conveyor and the kaolin is transported by a second belt conveyor, and the transport belt of the first belt conveyor and the transport belt of the second belt conveyor are arranged relative to each other so that the dry fine coal and kaolin are discharged at the same time.

[0015] A second aspect of an embodiment of the present invention provides a system for preparing dry mixed coal, comprising a first crusher, a screening device, a drying device, and a blending device, wherein:

[0016] The first crusher is used to crush low-rank raw coal;

[0017] Screening device, used to screen the crushed low-rank coal to obtain fine coal with a particle size of less than 50mm;

[0018] A drying device is used to dry the fine coal and remove 10-15% of the moisture in the fine coal to obtain dry fine coal;

[0019] The blending device is used to blend the dry fine coal with kaolin to obtain the improved and modified dry mixed coal.

[0020] Optionally, the system further comprises a second crusher for crushing the kaolin to less than 10 mm before blending the dried fine coal with the kaolin.

[0021] Optionally, the blending device includes a first belt conveyor and a second belt conveyor,

[0022] in:

[0023] The first belt conveyor is used to transport dry fine coal;

[0024] The second belt conveyor is used to transport kaolin;

[0025] The transport belt of the first belt conveyor and the transport belt of the second belt conveyor are arranged opposite to each other so that the dried fine coal and kaolin can be discharged at the same time.

[0026] Optionally, the blending device further includes a first weighing device, a second weighing device and a programmable logic controller, wherein:

[0027] a first weighing device electrically connected to the programmable logic controller, for weighing the mass of the dried fine coal transported by the first belt conveyor in real time and transmitting the mass to the programmable logic controller;

[0028] a second weighing device, electrically connected to the programmable logic controller, for weighing the mass of the kaolin transported by the second belt conveyor in real time and transmitting the mass to the programmable logic controller;

[0029] The programmable logic controller is electrically connected to the first belt conveyor and the second belt conveyor respectively, and is provided with a threshold value of the mass ratio of the dry fine coal and kaolin.

[0030] It is used to receive the mass of dry fine coal weighed by the first weighing device and the mass of kaolin weighed by the second weighing device, calculate the mixing mass ratio of dry fine coal and kaolin, and compare it with the mixing mass ratio threshold value, and adjust the belt speed of the first belt conveyor and the second belt conveyor according to the comparison result to control the mixing mass ratio of kaolin at 8-12%.

[0031] The third aspect of the embodiment of the present invention provides a dry mixed coal, which is obtained by processing using the above method or system, and comprises dry fine coal and kaolin, and the coal quality index is: total moisture M t 10~15%, ash content A ar The calorific value of coal is 11-16%. net,ar It is 4800~5400kcal.

[0032] In summary, the dry mixed coal provided in the embodiment of the present invention is obtained by crushing low-rank coal, drying it, and blending it with kaolin, that is, it is generated by combining the drying and quality improvement technology with the blending and modification technology. By removing part of the moisture in the low-rank coal fines through drying, the calorific value and combustion efficiency of the coal can be improved at a low cost, and pollutant emissions can be effectively reduced. By adding a certain proportion of kaolin to the dry fines, the dry fines can be quickly cooled and prevented from spontaneous combustion, while also adjusting the chemical composition of the coal ash, especially reducing the alkali-acid ratio of the coal ash, thereby effectively preventing the high alkali metal content from causing slagging and contamination of the boiler when the coal is burned in the boiler, thereby ensuring the stable operation of the boiler in the coal-fired power plant.

[0033] Furthermore, while ensuring the stable operation of the coal-fired power plant boiler, the economic and environmental benefits of the coal-fired power plant are also improved.

[0034] The embodiments of the present invention are suitable for processing low-rank coal with high alkali metal content and high moisture content and other coal resources with similar characteristics, and have wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1It is a structural schematic diagram of a system for preparing dry mixed coal according to an embodiment of the present invention.

[0036] In the figure: 1-screening device; 2-drying device; 3-first belt conveyor; 4-second belt conveyor; 5-programmable logic controller; 6-second crusher. DETAILED DESCRIPTION

[0037] To help those skilled in the art better understand the technical solutions of the embodiments of the present invention, the following will provide a clear and complete description of the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0038] In the description of the embodiments of the present invention, it should be noted that the term "upper" and the like to indicate an orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience and simplification of the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0039] In the description of the embodiments of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the described features. In the description of the embodiments of the present invention, the meaning of "plurality" is two or more, unless otherwise explicitly and specifically defined.

[0040] With the continuous growth of global demand for energy, the clean and efficient use of coal as one of the main energy sources has always been a research hotspot in the energy field.

[0041] Low-rank coal (coal with a long, smoky flame and a low degree of coalification) accounts for a significant portion of coal resources. However, the high alkali metal content and high moisture content of low-rank coal severely limit its application in industrial sectors such as coal-fired power plants.

[0042] High-moisture coal reduces combustion efficiency, impacts furnace combustion stability, and reduces the drying output of the pulverizing system. High alkali metal content can lead to slagging and contamination in boilers, reducing heat transfer efficiency, increasing slagging cleaning workload, and raising maintenance costs, seriously impacting the stable operation and economic benefits of coal-fired power plants.

[0043] In order to solve the above problems, various methods such as drying, washing, and chemical modification have been used to improve the quality of low-rank coal.

[0044] For example, by combining the quality improvement technologies of "microwave drying for sodium removal + washing + hot air drying of clean coal", high-sodium coal can be desodiumed and dried and dehydrated at the same time, which can reduce the harm of using high-sodium coal to boilers and improve the calorific value of the product coal.

[0045] For example, through the combined use of multiple quality improvement and modification technologies such as "multi-stage screening + coal slime dehydration + coal blending", while improving the yield of clean coal, the dehydrated and upgraded coal slime and clean coal are blended to achieve efficient utilization of coal slime and improve the comprehensive utilization rate of low-quality coal resources.

[0046] For example, by combining the two quality improvement technologies of "coal vibration air separation + low-temperature dehydration and drying", the calorific value of coal is increased twice, achieving deep quality improvement of low-quality coal and recycling of resources.

[0047] For example, by combining the two quality improvement technologies of "hot air drying + dry coal preparation", the coal quality is improved while the graded utilization of coal is achieved, thereby improving the overall economic benefits.

[0048] However, the aforementioned technologies all focus on improving the quality and comprehensive utilization of coal itself, while the problem of boiler slagging and fouling caused by high alkali metal content during coal combustion cannot be effectively addressed.

[0049] Based on this, an embodiment of the present invention provides a method for preparing dry mixed coal and the dry mixed coal, which mainly combines the drying and quality improvement technology with the blending and modification technology to obtain a dry mixed coal that can effectively prevent the problem of boiler slagging and contamination. Specifically, by removing part of the moisture in the low-rank coal and fine coal through drying, the calorific value and combustion efficiency of the coal can be improved at a low cost, and pollutant emissions can be effectively reduced. By adding a certain proportion of kaolin to the dry fine coal, the dry fine coal can be quickly cooled and prevented from spontaneous combustion, and the chemical composition of the coal ash can be adjusted, especially the alkali-acid ratio of the coal ash can be reduced, thereby effectively preventing the high alkali metal content from causing boiler slagging and contamination when the coal is burned in the boiler, thereby ensuring the stable operation of the boiler in the coal-fired power plant.

[0050] Specifically, an embodiment of the present invention discloses a method for preparing dry mixed coal, the method comprising:

[0051] Crushing and screening low-rank raw coal to obtain fine coal with a particle size of less than 50 mm;

[0052] Drying the fine coal to remove 10-15% of the moisture in the fine coal to obtain dry fine coal;

[0053] Mix the dry fine coal with kaolin to obtain the improved dry mixed coal

[0054] Another embodiment of the present invention discloses a system for preparing dry mixed coal, comprising a first crusher, a screening device, a drying device, and a blending device, wherein:

[0055] The first crusher is used to crush low-rank raw coal;

[0056] Screening device, used to screen the crushed low-rank coal to obtain fine coal with a particle size of less than 50mm;

[0057] A drying device is used to dry the fine coal and remove 10-15% of the moisture in the fine coal to obtain dry fine coal;

[0058] The blending device is used to blend the dry fine coal with kaolin to obtain the improved and modified dry mixed coal.

[0059] Another embodiment of the present invention discloses a dry mixed coal, which is obtained by processing using the above method or system, and comprises dry fine coal and kaolin, and its coal quality index is: total moisture M t 10~15%, ash content A ar The calorific value of coal is 11-16%. net,ar It is 4800~5400kcal.

[0060] The embodiment of the present invention combines the drying and upgrading technology with the blending and modification technology. By drying and removing part of the moisture in the low-rank coal, the calorific value and combustion efficiency of the coal can be improved at a low cost, and pollutant emissions can be effectively reduced. Subsequently, by adding a certain proportion of kaolin to the dried coal, the dried coal can be quickly cooled and prevented from spontaneous combustion. At the same time, the chemical composition of the coal ash can be adjusted, especially the alkali-acid ratio of the coal ash can be reduced, thereby effectively preventing the high alkali metal content in the coal combustion in the boiler from causing boiler slagging and contamination, ensuring the stable operation of the coal-fired power plant boiler, and improving the economic and environmental benefits of the coal-fired power plant. At the same time, the comprehensive utilization value of low-rank coal is improved, providing a coal-fired power plant with an environmentally friendly, efficient and economical coal pretreatment solution to meet the increasingly stringent environmental protection requirements and the social needs of improving energy utilization efficiency.

[0061] It should be noted that the embodiments of the present invention optimize the utilization mode of low-rank coal and improve the utilization efficiency through the comprehensive treatment of drying and quality improvement and blending modification, provide high-quality thermal coal for coal-fired power plants, and improve economic benefits. It is suitable for processing low-rank coal with high alkali metal content and high moisture content, but is not limited to this. It is also suitable for processing other coal resources with similar characteristics and has wide applicability.

[0062] Example 1

[0063] This embodiment discloses a method for preparing dry mixed coal, comprising: crushing and screening low-rank raw coal with high alkali metal content, high moisture content and low ash content to obtain fine coal with a particle size of less than 50 mm; drying the fine coal to remove 10-15% of the moisture in the fine coal to obtain dry fine coal; and blending the dry fine coal with kaolin to obtain a dry mixed coal after quality improvement and modification.

[0064] The coal quality indicators of low-rank raw coal are as follows: total moisture M t 21~32%, ash content A ar 2~7%, volatile matter V daf The sulfur content is 26-35%. t,d 0.1~1.2%, coal calorific value Q net,ar It is 4500~5100kcal.

[0065] After the low-rank raw coal is crushed, it is transported to the screening device using the first belt conveyor for screening according to particle size. The screening device uses a high-efficiency vibrating screen with a mesh size of 50mm to ensure the screening effect. The fine coal with a particle size of less than 50mm is sent to the drying device for drying.

[0066] The drying device adopts one of the following methods: tube drying, drum drying, fluidized bed drying, entrained bed drying, etc. After removing 10-15% of the moisture in the fine coal by drying, the calorific value of the dry fine coal obtained is Q net,ar Reaching 5200~5800kcal, the calorific value of coal is significantly improved compared with low-grade coal.

[0067] The blending mass ratio of kaolin is 8-12%. After the fine coal is dried, the surface temperature of the obtained dry fine coal reaches 40-70℃. By blending a specific proportion of kaolin, the surface temperature of the obtained dry mixed coal is reduced to <40℃, which can prevent the risk of spontaneous combustion. In addition, the total moisture content of the dry mixed coal is M t 10~15%, ash content A ar The calorific value of coal is 11-16%. net,ar It is 4800~5400kcal. Although the calorific value has decreased, it still remains in a higher calorific value range compared with low-rank coal. At the same time, the moisture content has decreased significantly, which can effectively improve the combustion performance and effectively reduce pollutant emissions. At the same time, the chemical composition of the coal ash has been adjusted, especially the alkali-acid ratio of the coal ash has been reduced, which can effectively prevent the slagging and fouling of the boiler during the combustion process and ensure the safe, efficient and stable operation of the boiler.

[0068] In addition, kaolin is widely available and inexpensive, making it suitable for processing large quantities of coal. Mixing it with dry fine coal can produce good economic benefits and achieve comprehensive utilization of resources.

[0069] Before mixing the dry fine coal with kaolin, the kaolin is also crushed to less than 10 mm to ensure the mixing effect.

[0070] like Figure 1 As shown, when the dry fine coal is mixed with kaolin, the dry fine coal is transported to the coal storage yard through the first belt conveyor 3, and at the same time, the kaolin is transported to the same coal storage yard through the second belt conveyor 4, and the transport belt of the first belt conveyor 3 and the transport belt of the second belt conveyor 4 are arranged relative to each other, so that the dry fine coal and kaolin are discharged at the same time, and effective mixing of the dry fine coal and kaolin is achieved during the discharge process.

[0071] The first belt conveyor 3 uses a first weighing device to weigh the mass of the transported dry fine coal in real time, and the second belt conveyor 4 uses a second weighing device to weigh the mass of the transported kaolin in real time. At the same time, a programmable logic controller (PLC) 5 is used to control the speed of the transport belts of the first belt conveyor 3 and the second belt conveyor 4. According to the requirements of the ash content, moisture and calorific value of the mixed coal, the transport belt speed is adjusted in real time to change the mixing ratio.

[0072] This embodiment also discloses a dry mixed coal, which is obtained by the above method, and comprises dry fine coal and kaolin, and its coal quality index is: total moisture M t 10~15%, ash content A ar The calorific value of coal is 11-16%. net,ar It is 4800~5400kcal.

[0073] Example 2

[0074] like Figure 1 As shown, this embodiment discloses a dry mixed coal preparation system, which is used for the above dry mixed coal preparation method, including a first crusher (not shown in the figure), a screening device 1, a drying device 2 and a blending device, wherein: the first crusher is used to crush low-rank coal raw coal; the screening device 1 is used to screen the low-rank coal raw coal crushed by the first crusher to obtain fine coal with a particle size of less than 50 mm; the drying device 2 is used to dry the fine coal obtained in the screening device 1, remove 10-15% of the moisture in the fine coal, and obtain dry fine coal; the blending device is used to blend the dry fine coal obtained in the drying device 2 with kaolin to obtain dry mixed coal after quality improvement.

[0075] The system further comprises a second crusher 6 for crushing the kaolin to a size of less than 10 mm before blending the dried fine coal with the kaolin.

[0076] The blending device includes a first belt conveyor 3 and a second belt conveyor 4, wherein: the first belt conveyor 3 is used to transport dry fine coal; the second belt conveyor 4 is used to transport kaolin; the transport belt of the first belt conveyor 4 and the transport belt of the second belt conveyor 4 are arranged relative to each other so that the dry fine coal and kaolin can be discharged at the same time.

[0077] The blending device further includes a first weighing device (not shown in the figure), a second weighing device (not shown in the figure) and a programmable logic controller 5.

[0078] The first weighing device is electrically connected to the programmable logic controller 5 and is used to weigh the mass of the dry fine coal transported by the first belt conveyor 3 in real time and transmit the mass to the programmable logic controller 5 .

[0079] The second weighing device is electrically connected to the programmable logic controller 5 and is used to weigh the mass of the kaolin transported by the second belt conveyor 4 in real time and transmit the mass to the programmable logic controller 5 .

[0080] The programmable logic controller 5 is electrically connected to the first belt conveyor 3 and the second belt conveyor 4 respectively, and is provided with a threshold value of the mixing mass ratio of dry fine coal and kaolin. It is used to receive the mass of dry fine coal weighed by the first weighing device and the mass of kaolin weighed by the second weighing device, calculate the mixing mass ratio of dry fine coal and kaolin, and compare it with the mixing mass ratio threshold value. According to the comparison result, the belt speed of the first belt conveyor 3 and the second belt conveyor 4 is adjusted to control the mixing mass ratio of kaolin at 8-12%.

[0081] This embodiment also discloses a dry mixed coal, which is obtained by the above system treatment, and its composition includes dry fine coal and kaolin, and its coal quality index is: total moisture M t 10~15%, ash content A ar The calorific value of coal is 11-16%. net,ar It is 4800~5400kcal.

[0082] In order to verify that the dry mixed coal obtained by the preparation method of the dry mixed coal provided by the embodiment of the present invention has the above-mentioned effect, it is described below with reference to specific test data.

[0083] Example 3

[0084] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0085] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 3-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0086] Table 3-1 Coal quality indicators of low-rank raw coal in Example 3

[0087]

[0088] The ash composition analysis results of the low-rank coal are shown in Table 3-2.

[0089] Table 3-2 Ash composition of low-rank raw coal in Example 3

[0090]

[0091] S2, sending the fine coal with a particle size of less than 50mm into the drying device for drying, removing 10% of the moisture in the fine coal, and obtaining dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 3-3.

[0092] Table 3-3 Coal quality indexes of dried fine coal in Example 3

[0093]

[0094] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 8%, and the dried mixed coal after quality improvement is obtained. The coal quality indicators of the dried mixed coal are shown in Table 3-4.

[0095] Table 3-4 Coal quality indexes of dry mixed coal in Example 3

[0096]

[0097] The ash composition analysis results of the dry mixed coal are shown in Table 3-5.

[0098] Table 3-5 Ash composition of dry mixed coal in Example 3

[0099]

[0100] It can be seen from Table 3-1 to Table 3-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 21.2% to 10.7%, ash content A ar Increased from 5.02% to 11.51%, calorific value Q net,ar The calorific value of coal was increased from 5086kcal to 5325kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 0.98 to 0.39, thus effectively preventing the problem of boiler slagging and contamination.

[0101] Example 4

[0102] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0103] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 4-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0104] Table 4-1 Coal quality indicators of low-rank raw coal in Example 4

[0105]

[0106] The ash composition analysis results of the low-rank coal are shown in Table 4-2.

[0107] Table 4-2 Ash composition of low-rank raw coal in Example 4

[0108]

[0109] S2, send the fine coal with a particle size of less than 50mm into the drying device for drying, remove 10% of the moisture in the fine coal, and obtain dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 4-3.

[0110] Table 4-3 Coal quality indexes of dried fine coal in Example 4

[0111]

[0112] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 10%, and the improved and modified dry mixed coal is obtained. The coal quality indicators of the dry mixed coal are shown in Table 4-4.

[0113] Table 4-4 Coal quality indexes of dry mixed coal in Example 4

[0114]

[0115] The ash composition analysis results of the dry mixed coal are shown in Table 4-5.

[0116] Table 4-5 Ash composition of dry mixed coal in Example 4

[0117]

[0118] It can be seen from Table 4-1 to Table 4-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 21.2% to 10.5%, ash content A ar Increased from 5.02% to 12.99%, calorific value Q net,arThe calorific value of coal was increased from 5086kcal to 5208kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 0.98 to 0.35, thus effectively preventing the problem of boiler slagging and contamination.

[0119] Example 5

[0120] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0121] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 5-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0122] Table 5-1 Coal quality indicators of low-rank raw coal in Example 5

[0123]

[0124] The ash composition analysis results of the low-rank coal are shown in Table 5-2.

[0125] Table 5-2 Ash composition of low-rank raw coal in Example 5

[0126]

[0127] S2, send the fine coal with a particle size of less than 50mm into the drying device for drying, remove 10% of the moisture in the fine coal, and obtain dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 5-3.

[0128] Table 5-3 Coal quality indexes of dried fine coal in Example 5

[0129]

[0130] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 12%, and the dried mixed coal after quality improvement is obtained. The coal quality indicators of the dried mixed coal are shown in Table 5-4.

[0131] Table 5-4 Coal quality indicators of dry mixed coal in Example 5

[0132]

[0133] The ash composition analysis results of the dry mixed coal are shown in Table 5-5.

[0134] Table 5-5 Ash composition of dry mixed coal in Example 5

[0135]

[0136] It can be seen from Table 5-1 to Table 5-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 21.2% to 10.3%, ash content A ar Increased from 5.02% to 14.52%, calorific value Q net,ar The calorific value of coal was increased from 5086kcal to 5113kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 0.98 to 0.33, thus effectively preventing the problem of boiler slagging and contamination.

[0137] Example 6

[0138] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0139] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 6-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0140] Table 6-1 Coal quality indicators of low-rank raw coal in Example 6

[0141]

[0142] The ash composition analysis results of the low-rank coal are shown in Table 6-2.

[0143] Table 6-2 Ash composition of low-rank raw coal in Example 6

[0144]

[0145] S2, send the fine coal with a particle size of less than 50mm into the drying device for drying, remove 12% of the moisture in the fine coal, and obtain dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 6-3.

[0146] Table 6-3 Coal quality indexes of dried fine coal in Example 6

[0147]

[0148] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 8%, and the dried mixed coal after quality improvement is obtained. The coal quality indicators of the dried mixed coal are shown in Table 6-4.

[0149] Table 6-4 Coal quality indicators of dry mixed coal in Example 6

[0150]

[0151] The ash composition analysis results of the dry mixed coal are shown in Table 6-5.

[0152] Table 6-5 Ash composition of dry mixed coal in Example 6

[0153]

[0154] It can be seen from Table 6-1 to Table 6-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 25.5% to 12.9%, ash content A ar Increased from 5.56% to 12.16%, calorific value Q net,ar The calorific value of coal was increased from 4783kcal to 5138kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 0.91 to 0.39, thus effectively preventing the problem of boiler slagging and contamination.

[0155] Example 7

[0156] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0157] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 7-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0158] Table 7-1 Coal quality indicators of low-rank raw coal in Example 7

[0159]

[0160] The ash composition analysis results of the low-rank coal are shown in Table 7-2.

[0161] Table 7-2 Ash composition of low-rank raw coal in Example 7

[0162]

[0163] S2, send the fine coal with a particle size of less than 50mm into the drying device for drying, remove 12% of the moisture in the fine coal, and obtain dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 7-3.

[0164] Table 7-3 Coal quality indexes of dried fine coal in Example 7

[0165]

[0166] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 10%, and the improved and modified dry mixed coal is obtained. The coal quality indicators of the dry mixed coal are shown in Table 7-4.

[0167] Table 7-4 Coal quality indicators of dry mixed coal in Example 7

[0168]

[0169] The ash composition analysis results of the dry mixed coal are shown in Table 7-5.

[0170] Table 7-5 Ash composition of dry mixed coal in Example 7

[0171]

[0172] It can be seen from Table 7-1 to Table 7-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 25.5% to 12.7%, ash content A ar Increased from 5.56% to 13.62%, calorific value Q net,ar The calorific value of coal was increased from 4783kcal to 5026kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 0.91 to 0.36, thus effectively preventing the problem of boiler slagging and contamination.

[0173] Example 8

[0174] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0175] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 8-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0176] Table 8-1 Coal quality indicators of low-rank raw coal in Example 8

[0177]

[0178] The ash composition analysis results of the low-rank raw coal are shown in Table 8-2.

[0179] Table 8-2 Ash composition of low-rank raw coal in Example 8

[0180]

[0181] S2, send the fine coal with a particle size of less than 50mm into the drying device for drying, remove 12% of the moisture in the fine coal, and obtain dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 8-3.

[0182] Table 8-3 Coal quality indexes of dried fine coal in Example 8

[0183]

[0184] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 12%, and the improved and modified dry mixed coal is obtained. The coal quality indicators of the dry mixed coal are shown in Table 8-4.

[0185] Table 8-4 Coal quality indexes of dry mixed coal in Example 8

[0186]

[0187] The ash composition analysis results of the dry mixed coal are shown in Table 8-5.

[0188] Table 8-5 Ash composition of dry mixed coal in Example 8

[0189]

[0190] It can be seen from Table 8-1 to Table 8-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 25.5% to 12.5%, ash content A ar Increased from 5.56% to 15.14%, calorific value Q net,ar The calorific value of coal was increased from 4783kcal to 4918kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 91 to 0.33, thus effectively preventing the problem of boiler slagging and contamination.

[0191] Example 9

[0192] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0193] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 9-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0194] Table 9-1 Coal quality indicators of low-rank raw coal in Example 9

[0195]

[0196] The ash composition analysis results of the low-rank coal are shown in Table 9-2.

[0197] Table 9-2 Ash composition of low-rank raw coal in Example 9

[0198]

[0199] S2, send the fine coal with a particle size of less than 50mm into the drying device for drying, remove 15% of the moisture in the fine coal, and obtain dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 9-3.

[0200] Table 9-3 Coal quality indexes of dried fine coal in Example 9

[0201]

[0202] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 8%, to obtain the improved and modified dry mixed coal. The coal quality indicators of the dry mixed coal are shown in Table 9-4.

[0203] Table 9-4 Coal quality indexes of dry mixed coal in Example 9

[0204]

[0205] The ash composition analysis results of the dry mixed coal are shown in Table 9-5.

[0206] Table 9-5 Ash composition of dry mixed coal in Example 9

[0207]

[0208] It can be seen from Table 9-1 to Table 9-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 29.8% to 14.1%, ash content A ar Increased from 4.25% to 11.02%, calorific value Q net,ar The calorific value of coal was increased from 4576kcal to 5108kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 0.80 to 0.31, thus effectively preventing the problem of boiler slagging and contamination.

[0209] Example 10

[0210] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0211] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 10-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0212] Table 10-1 Coal quality indicators of low-rank raw coal in Example 10

[0213]

[0214] The ash composition analysis results of the low-rank coal are shown in Table 10-2.

[0215] Table 10-2 Ash composition of low-rank raw coal in Example 10

[0216]

[0217] S2, send the fine coal with a particle size of less than 50mm into the drying device for drying, remove 15% of the moisture in the fine coal, and obtain dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 10-3.

[0218] Table 10-3 Coal quality indexes of dried fine coal in Example 10

[0219]

[0220] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 10%, and the improved and modified dry mixed coal is obtained. The coal quality indicators of the dry mixed coal are shown in Table 10-4.

[0221] Table 10-4 Coal quality indexes of dry mixed coal in Example 10

[0222]

[0223] The ash composition analysis results of the dry mixed coal are shown in Table 10-5.

[0224] Table 10-5 Ash composition of dry mixed coal in Example 10

[0225]

[0226] It can be seen from Table 10-1 to Table 10-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 29.8% to 13.9%, ash content A ar Increased from 4.25% to 12.55%, calorific value Q net,arThe calorific value of coal was increased from 4576kcal to 4996kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 0.80 to 0.29, thus effectively preventing the problem of boiler slagging and contamination.

[0227] Example 11

[0228] This embodiment discloses a method for preparing dry mixed coal, which uses the above-mentioned dry mixed coal preparation system, and the steps are as follows:

[0229] S1. Crush the low-rank raw coal with high alkali metal content and high moisture content as shown in Table 11-1, and use a high-efficiency vibrating screen to screen the crushed raw coal according to particle size to obtain fine coal with a particle size of less than 50 mm.

[0230] Table 11-1 Coal quality indicators of low-rank raw coal in Example 11

[0231]

[0232] The ash composition analysis results of the low-rank coal are shown in Table 11-2.

[0233] Table 11-2 Ash composition of low-rank raw coal in Example 11

[0234]

[0235] S2, send the fine coal with a particle size of less than 50mm into the drying device for drying, remove 15% of the moisture in the fine coal, and obtain dry fine coal. The coal quality indicators of the dry fine coal are shown in Table 11-3.

[0236] Table 11-3 Coal quality indexes of dried fine coal in Example 11

[0237]

[0238] S3, the dried fine coal and kaolin are transported to the same coal storage yard using belt conveyors with weighing equipment for blending, wherein the blending ratio of kaolin is 12%, and the improved and modified dry mixed coal is obtained. The coal quality indicators of the dry mixed coal are shown in Table 11-4.

[0239] Table 11-4 Coal quality indicators of dry mixed coal in Example 11

[0240]

[0241] The ash composition analysis results of the dry mixed coal are shown in Table 11-5.

[0242] Table 11-5 Ash composition of dry mixed coal in Example 11

[0243]

[0244]

[0245] It can be seen from Table 11-1 to Table 11-5 that after the comprehensive treatment of drying, upgrading and blending modification by the method of this embodiment, the total moisture content of low-rank coal M t From 29.8% to 13.7%, ash content A ar Increased from 4.25% to 13.97%, calorific value Q net,ar The calorific value of coal was increased from 4576kcal to 4886kcal. At the same time, the chemical composition of the coal ash was adjusted, and the alkali-acid ratio was reduced from 0.80 to 0.27, thus effectively preventing the problem of boiler slagging and contamination.

[0246] It should be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the embodiments of the present invention, and the embodiments of the present invention are not limited thereto. Those skilled in the art may make various modifications and improvements without departing from the spirit and substance of the embodiments of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the embodiments of the present invention.

Claims

1. A method for preparing dry mixed coal, characterized in that: include: Crushing and screening low-rank raw coal to obtain fine coal with a particle size of less than 50 mm; drying the fine coal to remove 10-15% of the moisture in the fine coal to obtain dried fine coal; The dried fine coal is mixed with kaolin to obtain a dried mixed coal with improved quality.

2. The method for preparing dry mixed coal according to claim 1, characterized in that: The coal quality index of the low-rank raw coal is: total moisture M t 21~32%, ash content A ar 2~7%, volatile matter V daf The sulfur content is 26-35%. t,d 0.1~1.2%, coal calorific value Q net,ar It is 4500~5100kcal.

3. The method for preparing dry mixed coal according to claim 1, characterized in that: The blending mass ratio of the kaolin is 8-12%.

4. The method for preparing dry mixed coal according to claim 1, characterized in that: Before the dried fine coal is blended with kaolin, the method further comprises: The kaolin is crushed to less than 10 mm.

5. The method for preparing dry mixed coal according to any one of claims 1 to 4, characterized in that: The step of mixing the dried fine coal with kaolin comprises: The dried fine coal is transported via a first belt conveyor (3), and the kaolin is transported via a second belt conveyor (4), and the transport belt of the first belt conveyor (3) and the transport belt of the second belt conveyor (4) are arranged relative to each other, and the dried fine coal and the kaolin are controlled to be discharged simultaneously.

6. A system for preparing dry mixed coal, characterized in that: The invention comprises a first crusher, a screening device (1), a drying device (2) and a blending device, wherein: The first crusher is used to crush low-rank raw coal; The screening device (1) is used to screen the crushed low-rank raw coal to obtain fine coal with a particle size of less than 50 mm; The drying device (2) is used to dry the fine coal and remove 10-15% of the moisture in the fine coal to obtain dried fine coal; The blending device is used to blend the dry fine coal with kaolin to obtain the improved and modified dry mixed coal.

7. The dry mixed coal preparation system according to claim 6, characterized in that: The invention also comprises a second crusher (6) for crushing the kaolin to less than 10 mm before blending the dried fine coal with the kaolin.

8. The dry mixed coal preparation system according to claim 6 or 7, characterized in that: The blending device comprises a first belt conveyor (3) and a second belt conveyor (4), wherein: The first belt conveyor (3) is used to transport the dried fine coal; The second belt conveyor (4) is used to transport the kaolin; The transport belt of the first belt conveyor (3) and the transport belt of the second belt conveyor (4) are arranged relative to each other, and the dried fine coal and the kaolin are controlled to be discharged simultaneously.

9. The dry mixed coal preparation system according to claim 8, characterized in that: The blending device further comprises a first weighing device, a second weighing device and a programmable logic controller (5), wherein: The first weighing device is electrically connected to the programmable logic controller (5) and is used to weigh the mass of the dried fine coal transported by the first belt conveyor in real time and transmit the mass to the programmable logic controller (5); The second weighing device is electrically connected to the programmable logic controller (5) and is used to weigh the mass of the kaolin transported by the second belt conveyor in real time and transmit the mass to the programmable logic controller (5); The programmable logic controller (5) is electrically connected to the first belt conveyor and the second belt conveyor respectively, and is provided with a threshold value of the mixing mass ratio of dry fine coal and kaolin; it is used to receive the mass of the dry fine coal weighed by the first weighing device and the mass of the kaolin weighed by the second weighing device, calculate the mixing mass ratio of the dry fine coal and the kaolin, and compare it with the mixing mass ratio threshold value, and adjust the belt speed of the first belt conveyor and the second belt conveyor according to the comparison result, so that the mixing mass ratio of the kaolin is controlled at 8-12%.

10. A dry mixed coal, characterized in that: The coal is obtained by processing the coal using the preparation method according to any one of claims 1 to 5, or by using the preparation system according to any one of claims 6 to 9; the coal comprises dried fine coal and kaolin, and the coal quality index is: total moisture M t 10~15%, ash content A ar The calorific value of coal is 11-16%. net,ar It is 4800~5400kcal.

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