Coal slurry concentration comprehensive treatment method based on multi-module cooperation

Abstract

The invention discloses a multi-module synergetic coal slurry concentration comprehensive treatment system and method, which can improve the coal slurry concentration to 64.5%, increase the effective gas (CO + H2) gas yield by 1.5%, reduce the specific coal consumption by 12kg / 1000Nm < 3 > and reduce the specific oxygen consumption by 16Nm < 3 > / 1000Nm < 3 > through circular grinding to optimize the particle size distribution, reduce the viscosity through steam heating, inhibit slurry overflow through a screening structure, and control non-lubricating residual moisture through flash steam emission. And the CO2 emission is reduced by about 3.2%, and the annual cost is saved by about 15477000 yuan according to a synthetic ammonia device with annual output of 400,000 tons. The device is adaptive to an existing gasification furnace production line, is low in improvement cost, and has the characteristics of high efficiency, energy conservation and environmental protection.

Description

Technical Field

[0001] The present invention relates to a water-coal slurry preparation technology in the coal chemical industry, and specifically to a comprehensive treatment system and method for significantly improving the coal slurry concentration and gasification efficiency through the synergistic effects of cyclic grinding, temperature control, screening optimization, and flash steam emission. The system is suitable for the preparation and treatment of high-concentration coal slurries in coal gasification processes. Background Art

[0002] The raw coal is ground with water and additives in the pulverizer to achieve the desired particle size distribution, resulting in a coal slurry concentration of approximately 60%-62% (the concentration is controlled towards 62% during normal operation). The coal slurry overflowing from the pulverizer passes through a drum screen at the pulverizer outlet to remove large particles. It then flows by gravity into the pulverizer outlet trough, where an agitator homogenizes the slurry and keeps it suspended. The slurry is then pumped through the pulverizer outlet trough to the coal slurry tank in the gasification section for gasification.

[0003] The existing coal-water slurry preparation process is subject to the multi-module coordination defect, and the coal slurry concentration has been lower than the ideal value (62.5%) for a long time. The core contradictions are as follows: Imbalance between particle size distribution and grinding efficiency: Single grinding results in a single peak structure of coal slurry (porosity > 25%, bulk density ≤ 1.16 g / cm 3 ), non-lubricating residual moisture accounts for 38%-40%, resulting in increased gasification heat loss (specific coal consumption and specific oxygen consumption increase by 5%-8%, and CO2 emissions increase by 10%-15%). While adding existing supporting ultrafine grinding technology can increase the concentration to 64%, the equipment cost increases by 30%.

[0004] Low temperature and high viscosity exacerbate slurry overflow: Coal slurry viscosity increases sharply with temperature drop (up to 1000 mPa·s), forcing an increase in the amount of process water and coal slurry additives, resulting in a 1% decrease in coal slurry concentration (a 0.74% decrease in gas production efficiency).

[0005] Sieve hole structure defects: Analysis shows that to meet the process requirements for water-coal slurry particle size distribution (<8 mesh 100%, <14 mesh 98%-100%, <40 mesh 93%-95%, <200 mesh 45%-58%, <325 mesh 30%-40%), the current drum screen uses a mesh size of 3.0-3.6mm (width) × 20mm (length). The current drum screen (specification: Ø2800*3200mm, punched type (aperture 3.5*20mm, material 316L)) is used for control. Key bottlenecks exist: First, particle size control conflicts with gasification efficiency. When the mesh width exceeds 3.8mm, the coal slurry particle size increases, resulting in reduced atomization in the gasifier, incomplete combustion, reduced gas production, and increased residual carbon in the ash (impacting economic efficiency). Coarse particles easily cause coal slurry stratification and sedimentation, increasing the risk of pipeline blockage and leading to unplanned downtime. Large particles increase equipment wear and shorten the life of key components. The second is the defects in the screen hole structure and the overflow problem: the existing screen hole (3.0mm×20mm) has insufficient effective screening area (the interval accounts for 4%), and the coal slurry flow resistance is large; the slurry congestion leads to an overflow rate of 3%-5%, further restricting the screening efficiency and the improvement of water-coal slurry concentration.

[0006] Existing screening technology is limited by particle size control accuracy and structural defects, resulting in an interlocking effect of "low screening efficiency → overflow → limited concentration". It is necessary to optimize the sieve hole parameters or develop new grading technology to break through the bottleneck.

[0007] Design defects of the swirl plate: The low swirl plate (70mm) results in a short residence time of the coal slurry (<10s), weak centrifugal stratification, and insufficient separation of large particles. Due to the insufficient height of the swirl plate, a large amount of coal slurry overflows the swirl plate and overflows the drum screen, resulting in increased pulping costs.

[0008] Non-lubricating residual moisture: Flash steam from the coal slurry tank is not effectively discharged, and non-lubricating residual moisture increases the proportion of coal slurry. Existing technologies rely on single optimization (such as additive ratio and moisture content adjustment) and cannot systematically address the synergistic conflicts between particle size distribution, screening efficiency, and temperature-viscosity characteristics. A comprehensive concentration technology with multi-module linkage is required. Summary of the Invention

[0009] In response to the above technical problems, the present invention provides a comprehensive treatment method for coal slurry concentration based on multi-module collaboration, comprising the following steps: (1) Raw material proportioning and pretreatment: The raw coal enters the weighing feeder, is mixed with water and additives, and then sent to the mill for grinding to obtain coal slurry; (2) After the large particles are separated by the first-stage drum screen, the coal slurry flows to the mill discharge trough by gravity. The circulation ratio is controlled by the low-pressure coal slurry pump and the coal slurry returns to the mill for secondary grinding through the circulation grinding pipeline; (3) The uncirculated coal slurry is sent to the secondary drum screen for screening; (4) The material screened by the secondary drum screen enters the coal slurry tank, and the material is sent to the gasification furnace at the bottom of the coal slurry tank.

[0010] In some embodiments, a circulating grinding pipeline is connected to the pipeline behind the low-pressure coal slurry pump outlet valve, and the outlet of the circulating grinding pipeline is set at the material port of the weighing feeder, which is conducive to returning the circulating coal slurry to the mill for re-grinding to increase the fine particles of the coal slurry. In order to achieve the above purpose, the patent of the present invention provides a bimodal grading circulating grinding pipeline for increasing the concentration of coal slurry. The circulating grinding pipeline is connected to the low-pressure coal slurry pump outlet and the weighing feeder material port at both ends, and is equipped with a flow control valve and a flushing water valve to achieve an adjustable 10-20% of the total coal slurry circulation amount; the uncirculated coal slurry is sent to the secondary drum screen; the material screened by the secondary drum screen enters the coal slurry tank, and the material is sent to the gasification furnace at the bottom of the coal slurry tank.

[0011] The above grinding conditions are adopted and the mill circulation grinding pipeline is used to grind the coarse particles of 150-200μm to account for 40-50%, and the fine particles of 15-20μm to account for 20-30%, forming a bimodal gradation on the whole and a tighter stacking structure.

[0012] In the preferred embodiment, the above grinding conditions are adopted and the mill circulation grinding pipeline is used to grind the coarse particles of 150-200 μm to account for 43% and the fine particles of 15-20 μm to account for 23%, forming a bimodal gradation as a whole.

[0013] Steam is injected into the mill inlet through a low-pressure steam pipeline at a pressure of 0.3-0.5 MPa, a temperature of 130°C-140°C, and a flow rate of 4-6 tons / hour. The coal slurry temperature is regulated in real time to a range of 55°C to 70°C. At this temperature, the viscosity is reduced to below 551 mPa·s based on the viscosity-temperature model (μ = -5.12T + 909.4), thereby increasing the slurry screening rate.

[0014] The novel mesh structure of a water-coal slurry drum screen optimizes the mesh size from the existing 3.0mm x 20mm to 3.0mm x 40mm, doubling the mesh length while maintaining the original mesh width. This improvement significantly expands the screening area and effectively addresses the problems of high overflow rates (3%-5%) and low screening efficiency (75%) caused by insufficient screening area in traditional meshes. The optimized mesh structure improves coal slurry fluidity, raising screening efficiency to over 95%, reducing overflow rates to below 1%, and simultaneously increasing coal slurry concentration by over 0.5%, preferably over 1%.

[0015] The drum screen is equipped with multiple layers of cyclone plates, which are 100-110mm high and made of 304L stainless steel. The coal slurry residence time is extended to 5-10 seconds, and the overflow rate is reduced to <1%.

[0016] In some preferred cases, the mesh size of the secondary drum screen is 3.0 mm×40 mm, and the height of the cyclone plate in the drum screen is 100 mm.

[0017] By adding fan exhaust ducts and condensate drain pipes, the coal slurry moisture content is effectively reduced and the slurry concentration is increased. The system consists of a coal slurry tank, fan, condensate drain pipe, agitator, and condensate water seal. After the slurry is heated and viscosity reduced, it enters the slurry tank. The fan exhausts flash steam through a DN500 exhaust pipe. The condensate drain pipe collects and discharges condensate, and the agitator ensures uniform heating of the coal slurry. This method significantly reduces the moisture content of the coal slurry through flash steam discharge and condensate separation, improving the efficiency and quality of coal slurry processing.

[0018] In step (1), a low-pressure coal slurry pump is used to circulate the slurry with a volume fraction of 10%-20% to the mill. The circulation pipeline is DN80, the porosity is ≤12%, and the bulk density is 1.20-1.28g / cm 3 .

[0019] When the recycle ratio exceeds 20%, the proportion of fine particles exceeds the critical value (V_fine / V_voids>0.8), the coarse particle skeleton structure collapses, and the coal slurry performance decreases. Therefore, the recycle ratio should be controlled within 10%-20%, preferably 15%-20%.

[0020] Uncirculated coal slurry is 77-97m 3 / h enters the secondary drum screen.

[0021] The mesh size of the secondary drum screen is 3.0mm×(40-45)mm. Multiple layers of cyclone plates are set inside the drum screen. The height of the cyclone plates inside the drum screen is 100-110mm and the material is stainless steel 304L.

[0022] In some preferred cases, the mesh size of the secondary drum screen is 3.0 mm×40 mm, and the height of the cyclone plate in the drum screen is 100 mm.

[0023] The size of the drum screen holes is extended by length rather than width, so as to avoid the increase of the flow resistance of the coal slurry without changing the particle size of the coal slurry. For example, if it is optimized to 3.0mm×40mm, the screening area will increase by 1.6m 2 , screening efficiency increased to 95%.

[0024] For example, the height of the swirl plate is increased from 70mm to 100mm, which effectively intercepts the coal slurry and guides the coal slurry to increase the swirl dispersion flow path. The coal slurry residence time is extended to 5-10 seconds, such as 15s-20s, which increases the screening area and reduces the overflow rate to below 1%, such as 0.8%, or preferably 0.5%.

[0025] By synergistically optimizing the screen hole parameters and the swirl plate structure, the interlocking contradiction of "screening-overflow" in traditional drum screens is broken through, and the system economy is improved while ensuring the stability of coal slurry concentration.

[0026] In step (5), the flash steam at the top of the coal slurry tank is exhausted by a centrifugal fan, and the condensate flows into the water seal tank through the guide pipe.

[0027] The centrifugal fan has an air volume of 8,000 to 10,000 m³ / h and a negative pressure of -5 to -10 kPa. The exhaust duct is DN500. Combined with a condensate drain pipe and water seal tank, this improves flash steam discharge efficiency and reduces non-lubricating residual moisture. The condensate water seal tank has a liquid level of 350-400 mm.

[0028] By adopting the technical solution of the present invention, the process of circulating grinding to optimize particle size distribution → steam heating to reduce viscosity → screening to extend residence time → flash steam discharge to control water content is used. The final coal slurry concentration is increased from 62.5% to above 64%, more preferably to above 64.5%, and even more preferably to above 65.0%. The effective gas (CO+H2) production is increased by more than 1.5%, and the specific coal consumption is reduced by 12kg / 1000Nm 3 Above, oxygen consumption is reduced by 16Nm 3 / 1000Nm 3 As a result, CO2 emissions were reduced by approximately 3.2%, and annual costs were saved by more than 15.477 million yuan. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 : Schematic diagram of the integrated treatment system.

[0030] In the figure, 1 is the raw coal silo, 2 is the weighing feeder, 3 is the mill feed pipe, 4 is the mill water valve, 5 is the additive valve, 6 is the low-pressure steam pipeline valve, 7 is the mill, 8 is the first-stage drum screen, 9 is the first-stage drum screen coal slurry diversion pipe, 10 is the first-stage drum screen large particle material pipe, 11 is the waste coal slurry pool, 12 is the agitator, 13 is the mill discharge trough, 14 is the low-pressure coal slurry pump inlet valve, 15 is the low-pressure coal slurry pump inlet pipeline, 16 is the low-pressure coal slurry pump, 17 is the low-pressure coal slurry pump outlet valve, 18 is the low-pressure coal slurry pump outlet pipeline, 19 is the second-stage drum screen inlet valve, 20 is the second-stage drum screen, 21 is the second-stage drum screen large particle material pipe, 22 is the second-stage drum screen coal slurry diversion pipe, 23 is the agitator, 24 is the flash steam discharge pipe, 25 is the flash steam discharge fan, 26 is the condensate diversion pipe, 27 is the condensate water seal tank, 28 is the condensate water seal tank overflow pipe, 29 is the coal slurry tank, and 30 is the high-pressure coal slurry pump inlet valve. 31 high-pressure coal slurry pump inlet pipeline, 32 high-pressure coal slurry pump, 33 high-pressure coal slurry pump outlet valve, 34 high-pressure coal slurry pump outlet pipeline, 35 circulating grinding pipeline, 36 circulating valve 1#, 37 circulating valve 2#, 38 flushing water valve 1#, 39 flushing water valve 2#, 40 waste coal slurry return to mill control valve, 41 waste coal slurry return to mill pipeline.

[0031] Figure 2 This is the viscosity-temperature linear relationship curve in Example 1.

[0032] Figure 3 A comparison diagram of the traditional sieve holes and the sieve holes of the present invention.

[0033] In the figure, 1' is the width of the traditional sieve hole, 2' is the length of the traditional sieve hole, and 3' is the length between the traditional sieve holes and the sieve holes. In the figure, 4' is the length of the new sieve hole, and 5' is the length between the new sieve hole and the sieve hole partition. Figure 4 : Comparison diagram of the structures of the traditional swirl plate and the swirl plate of the present invention; In the figure, 1-1 is a screen, 1-2 is a swirl plate, 1-4 is a coal slurry guide pipe, and 1-5 is a mill discharge chute; In the figure, 2-1 is a screen, 2-2 is a swirl plate, 2-3 is an optimized swirl plate, 2-4 is a coal slurry guide pipe, and 2-5 is a mill discharge trough.

[0034] Figure 5 : Flash steam discharge system structure diagram.

[0035] In the figure, 19 is a secondary drum screen inlet valve, 20 is a secondary drum screen, 21 is a secondary drum screen large particle material pipe, 22 is a secondary drum screen coal slurry guide pipe, 24 is a flash steam discharge pipe, 25 is a flash steam discharge fan, 26 is a condensate guide pipe, 27 is a condensate water seal tank, and 28 is a condensate water seal tank overflow pipe. DETAILED DESCRIPTION

[0036] Example 1 like Figure 1 、 Figure 3 Middle B, Figure 4 Middle B, Figure 5 A comprehensive coal slurry concentration processing system based on multi-module collaboration is obtained by the structure of the raw coal silo 1, which is connected to the inlet of the weighing feeder 2, and the bottom outlet of the weighing feeder 2 is connected to the mill 7 through the mill feed pipe 3; The outlet of the mill 7 is connected to the first-stage drum screen 8, and the bottom outlet of the first-stage drum screen 8 is connected to the mill discharge chute 13 through the first-stage drum screen coal slurry guide pipe 9; The bottom outlet of the mill discharge trough 13 is connected to the secondary drum screen 20 via the low-pressure coal slurry pump 16, and the bottom outlet of the secondary drum screen 20 is connected to the coal slurry tank 29 via the secondary drum screen coal slurry guide pipe 22; The bottom outlet of the coal slurry tank 29 is connected to the gasifier via a high-pressure coal slurry pump 32 .

[0037] The mill feed pipe 3 is provided with a coal grinding water pipeline, an additive inlet pipeline, and a low-pressure steam pipeline, and is sequentially provided with a coal grinding water valve 4, an additive valve 5, and a low-pressure steam pipeline 6.

[0038] The bottom outlet of the mill discharge trough 13 is also connected to another inlet of the weighing feeder 2 through the low-pressure coal slurry pump 16, the low-pressure coal slurry pump outlet pipeline 18, and the circulating grinding pipeline 35.

[0039] The bottom outlet of the mill discharge trough 13 is also connected to another inlet of the weighing feeder 2 through a low-pressure coal slurry pump 16.

[0040] The top of the coal slurry tank 29 is connected to the flash steam discharge fan 25 through the flash steam discharge elbow 24.

[0041] The bottom outlet of the flash steam discharge elbow 24 is connected to the inlet of the condensate water seal tank 27 through the condensate guide pipe 26 .

[0042] The overflow port of the condensate guide pipe 26 is connected to the condensate water seal tank overflow pipe 28 .

[0043] The mesh size of the first-stage drum screen or the second-stage drum screen is 3.0 mm × 40 mm, and the height of the cyclone plate in the drum screen is 100 mm.

[0044] It is understandable that corresponding valves are provided on different pipelines.

[0045] Example 2 The device is the same as in Example 1, except that the mesh size of the first or second drum screen is 3.0 mm × 20 mm. Figure 3 (as shown in A in the figure).

[0046] Example 3 The device is the same as in Example 1, except that the height of the cyclone plate in the first or second drum screen is 70 mm. Figure 4 (as shown in A in the figure).

[0047] Example 4 The following process is carried out using the device of Example 1: Coal quality parameters: Inner Mongolia coal HGI=60, Mad=6%, Aad=9.2%.

[0048] (1) Raw material proportioning and pretreatment: The raw coal enters the weighing feeder, is mixed with water and additives (sodium lignin sulfonate), and is then sent to the mill for grinding to obtain coal slurry. During the grinding process, steam is injected into the mill inlet through a low-pressure steam pipeline. The steam pressure is 0.3-0.5 MPa, the steam temperature is 130℃-140℃, and the flow rate is 4.5 tons / h. The coal slurry temperature is adjusted to 65℃~70℃ in real time.

[0049] (2) The sodium lignin sulfonate lignin (a natural high molecular polymer second only to cellulose and chitin in nature) is prepared by sulfonation modification and is derived from sulfite pulping wastewater from the paper industry. It has good solubility and high surface activity and dispersibility, and is widely used to increase coal slurry concentration, reduce viscosity, and improve fluidity and stability.

[0050] (3) Circulation grinding and bimodal grading: After the large particles are separated by the first-stage drum screen 8, the coal slurry flows to the mill discharge trough 13 by gravity, and the circulation ratio (volume ratio is 20%) is controlled by the low-pressure coal slurry pump 16. It returns to the mill for secondary grinding through the circulation grinding pipeline 35; the uncirculated coal slurry (main flow 77m 3 / h) is sent to the secondary drum screen 20 for screening.

[0051] (4) The above grinding conditions are used to grind the powder through the mill circulation grinding pipeline until the coarse particles of 150-200 μm account for 43% and the fine particles of 15-20 μm account for 23%, forming a bimodal gradation on the whole, forming a more compact stacking structure.

[0052] (5) Synchronous start of steam heating: Low-pressure steam pipeline 6 (0.3 MPa, 133 °C, flow rate 5 tons / h) injects steam into the mill inlet, and the coal slurry temperature is adjusted to 70 °C in real time, so that the slurry viscosity is controlled to about 551 mPa·s.

[0053] The hole structure of the first-stage drum screen and the second-stage drum screen: The hole size of the drum screen is 3.0mm×40mm, and the spacing between the holes is 5mm. The screening area can be increased by 1.6m 2 (By extending the length of the sieve holes rather than the width, it is ensured that the flow resistance of the coal slurry is not increased without changing the coal slurry particle size).

[0054] Improvement of swirl plate: the height of swirl plate is 100mm, the residence time of coal slurry is 15s, and the overflow rate is 0.8%.

[0055] The cyclone plate is used to grade and concentrate the water-coal slurry, separate particles of different sizes through centrifugal force, and improve the slurry quality.

[0056] The slurry enters the cyclone tangentially, creating a rotating flow field. Fine particles, driven by centrifugal force, pass through the screen and into the discharge chute. Large particles intercepted by the screen are forced out of the drum screen by the spiral baffle. The cyclone plate is a guide plate inside the drum screen, used to optimize flow distribution and enhance separation efficiency. Its advantages are its compact structure and lack of moving parts, making it suitable for rapid classification of high-concentration slurries.

[0057] The material screened by the secondary drum screen enters the coal slurry tank, and the bottom of the coal slurry tank sends the material to the gasifier.

[0058] The flash steam at the top of the coal slurry tank 29 is extracted by the fan 25 (negative pressure -5kPa) and enters the condensate recovery system through the DN500 pipe 24; the condensate flows into the water seal tank 27 (liquid level height 350mm) through the guide pipe 26, reducing the proportion of non-lubricating residual moisture.

[0059] The above technical solution has the following beneficial effects: Invention Benefit Calculation Table (Annual Production of 400,000 Tons of Synthetic Ammonia) Table 1

[0060] Benefit calculation: The price of synthetic ammonia is 2,300 yuan / ton Increase in production benefits: 15% Total annual benefits increased to 15.477 million yuan Benefit composition: Energy saving benefit: 2 million yuan (1.2 million yuan in coal saving + 800,000 yuan in oxygen saving) Increased production benefit: 13.477 million yuan (5,916 tons x 2,300 yuan / ton) The proportion of increased production benefits increased to 87.1% Key parameter verification: Specific coal consumption: 12kg / kNm 3 / 2% = 6kg / kNm 3 Specific oxygen consumption: 16Nm 3 / kNm 3 / 2% = 8Nm³ / kNm 3 Synthetic ammonia production increase rate: 5,916 tons / 400,000 tons = 1.48% Calculation basis: Coal price: 1,000 yuan / ton Oxygen price: 0.5 yuan / Nm 3 Annual effective gas demand: 100,000 thousand Nm 3 When the invented technology achieves a 2% increase in coal slurry concentration, the annual comprehensive benefit will reach RMB 15.477 million. Note: The technical solution for increasing the concentration of coal slurry by circulating grinding is as follows: that is, the solution of Example 1 and Example 4 is adopted, except that steam is not injected in step (1); the mesh size of the drum screen is 3.0 mm × 20 mm for the first-stage drum screen or the second-stage drum screen; the height of the cyclone plate in the first-stage drum screen or the second-stage drum screen is 70 mm; and the steam heating step of step (5) is not performed.

[0061] The technical solution for increasing the temperature and concentration of coal slurry is as follows: the solution of Example 1 and Example 4 is adopted, except that the circulation is not performed in step (1); the mesh size of the drum screen is 3.0 mm × 20 mm for the first-stage drum screen or the second-stage drum screen; the height of the swirl plate in the first-stage drum screen or the second-stage drum screen is 70 mm; and the steam heating step of step (5) is not performed.

[0062] The technical solution for lengthening the mesh of the drum screen to increase the concentration is as follows: that is, the solution of Example 1 and Example 4 is adopted, except that the circulation is not performed in step (1); steam is not injected in step (1); the height of the cyclone plate in the first-stage drum screen or the second-stage drum screen is 70 mm; and the steam heating step of step (5) is not performed.

[0063] The technical solution for increasing the concentration of the swirl plate is as follows: that is, the solution of Example 1 and Example 4 is adopted, except that the circulation is not performed in step (1); steam is not injected in step (1); the mesh size of the drum screen is 3.0 mm × 20 mm for the first-stage drum screen or the second-stage drum screen; and the steam heating step of step (5) is not performed.

[0064] The technical solution for the flash steam condensation concentration data is as follows: that is, the solution of Example 1 and Example 4 is adopted, except that the circulation is not performed in step (1); steam is not injected in step (1); the mesh size of the drum screen is 3.0 mm × 20 mm for the first-stage drum screen or the second-stage drum screen; the height of the cyclone plate in the first-stage drum screen or the second-stage drum screen is 70 mm.

[0065] The data in “Total” are obtained from the experimental scheme of the complete steps of Example 1 and Example 4.

[0066] The coal slurry concentration was increased to 64.5% by adopting the scheme of this embodiment. After one month of operation, the coal slurry concentration was stabilized at 64.6%. The conventional process in the background art is: that is, the schemes of Example 1 and Example 4 are adopted, except that in step (1), circulation and steam injection are not performed; the mesh size of the drum screen is 3.0mm×20mm for the first-stage drum screen or the second-stage drum screen; the height of the swirl plate in the first-stage drum screen or the second-stage drum screen is 70mm; and the steam heating step of step (5) is not performed. The coal slurry concentration was increased to 62.5±0.2% by adopting this scheme. After one month of operation, the coal slurry concentration was stabilized at 60.8±0.4%.

[0067] Example 5 The process of "Technical solution of coal slurry circulation grinding and concentration improvement data" in Example 4 was adopted, and the particle size distribution parameters when the circulation ratio was controlled by the low-pressure coal slurry pump 16 at 10%, 15%, 20%, and 25% were shown in Table 2: Table 2

[0068] Note: When the circulation ratio exceeds 20%, the coarse particle skeleton structure collapses, resulting in a decrease in coal slurry performance. Therefore, the circulation ratio should be controlled between 15 and 20%, preferably 20%.

[0069] The effects obtained by using different particle sizes are as follows: When the circulation ratio of the solution of this embodiment is 10%, the coal slurry concentration is increased to 62.70%. After one month of operation, the coal slurry concentration is stabilized at 62.75%.

[0070] When the circulation ratio of the solution of this embodiment is 15%, the coal slurry concentration is increased to 62.81%. After one month of operation, the coal slurry concentration is stabilized at 62.90%.

[0071] When the scheme of this embodiment is adopted and the circulation ratio is 20%, the coal slurry concentration is increased to 62.96%. After one month of operation, the coal slurry concentration is stabilized at 62.98%.

[0072] When the circulation ratio of the solution of this embodiment is 25%, the coal slurry concentration is increased to 62.79%. After one month of operation, the coal slurry concentration is stabilized at 62.60%.

[0073] By synergistically optimizing the screen hole parameters and the swirl plate structure, the interlocking contradiction of "screening-overflow" in traditional drum screens is broken through, and the system economy is improved while ensuring the stability of coal slurry concentration.

[0074] The swirl plate is designed in an arc shape on the inner wall of the drum screen, guiding the movement trajectory of large particles in the coal slurry in a spiral from inlet to outlet. However, the 70mm high swirl plate cannot guide the coal slurry to increase the flow path (screening area), so most of the coal slurry overflows the swirl plate and overflows the drum screen, restricting the increase in coal slurry concentration and increasing the slurry making cost.

Claims

1. A comprehensive treatment method for coal slurry concentration based on multi-module collaboration, characterized in that: The following steps are involved: (1) Raw material proportioning and pretreatment: The raw coal enters the weighing feeder, is mixed with water and additives, and then sent to the mill for grinding to obtain coal slurry; (2) Circulation grinding and bimodal grading: After the large particles are separated by the first-stage drum screen, the coal slurry flows to the mill discharge trough by gravity. The circulation ratio is controlled by the low-pressure coal slurry pump and returns to the mill for secondary grinding through the circulation grinding pipeline; (3) The uncirculated coal slurry is sent to the secondary drum screen for screening; (4) The material screened by the secondary drum screen enters the coal slurry tank, and the material is sent to the gasification furnace at the bottom of the coal slurry tank.

2. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 1 is characterized in that: During the grinding process of step (1), a low-pressure steam pipeline is used to inject steam into the mill inlet. The steam pressure is 0.3-0.5 MPa, the steam temperature is 130°C-140°C, and the flow rate is 4-6 tons / h. The coal slurry temperature is adjusted to 55°C to 70°C in real time.

3. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 1 is characterized in that: After grinding by a mill, the coarse particles are 150-200μm, accounting for 40-50%, and the fine particles are 15-20μm, accounting for 20-30%.

4. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 1 is characterized in that: The mesh size of the first-stage drum screen is 3.0 mm × (40-45) mm, and the mesh size is 5-6 mm; Multiple layers of cyclone plates are set in the first-stage drum screen. The height of the cyclone plates in the drum screen is 100-110mm and the material is stainless steel 304L.

5. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 1 is characterized in that: In step (2), a low-pressure coal slurry pump is used to circulate the slurry with a volume fraction of 10%-20% to the mill.

6. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 4 is characterized in that: A low-pressure coal slurry pump is used to circulate the slurry with a volume fraction of 15%-20% to the mill.

7. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 4 is characterized in that: Uncirculated coal slurry is 77-97m 3 / h enters the secondary drum screen.

8. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 1 is characterized in that: The mesh size of the secondary drum screen is 3.0mm×(40-45)mm, the height of the cyclone plate in the secondary drum screen is 100-110mm, and the material is stainless steel 304L.

9. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 1, characterized in that: In step (4), the flash steam at the top of the coal slurry tank is exhausted by a centrifugal fan, and the condensate flows into the water seal tank through the guide pipe.

10. The comprehensive treatment method for coal slurry concentration based on multi-module collaboration according to claim 9, characterized in that: The air volume of centrifugal fans is 8000~10000m 3 / h, negative pressure -5~-10kPa, the liquid level height of the condensate water seal tank is 350-400mm.

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