Coal quality intercommunication switching free precise blending and conveying system for raw coal bunker
Patent Information
- Application Number
- CN202611008727.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-08
- Publication Date
- 2026-09-01
AI Technical Summary
[0007]为克服现有煤仓分仓改造工期长、投资高、煤种切换滞后、运维量大、施工危险、仓体载荷增加等缺陷，本发明提供一种原煤仓煤质互通切换自由精准掺配输送系统，实现相邻原煤仓双向互通，2 分钟内完成高低热值煤快速切换，精准控制掺烧比例，改造量小、可在线施工、运维简单、投资回收期短
1.改造成本低、工程量小：仅增设底部互通螺旋机构，改造费用较中隔墙、虾米多路分仓节省 60%，无需仓内大型焊接作业；
Smart Images
Figure CN122667408A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of coal blending technology in thermal power plant raw coal bunkers, specifically involving a raw coal conveying system that enables mutual exchange, rapid switching, and precise blending of coal quality between adjacent raw coal bunkers, suitable for deep peak shaving and flexible coal blending scenarios at peak load in thermal power units. Background Technology
[0002] Coal costs consistently account for over 70% of the total power generation costs at thermal power plants, making it the most crucial control point for cost reduction, efficiency improvement, and increased operating profits. Under the premise of stable boiler combustion conditions and compliance with environmental emission standards, maximizing the blending ratio of low-calorific-value, low-quality economic coal is the most direct and effective technical path to reduce fuel costs per unit of power generation. Currently, the construction of new power systems in China is continuously advancing, with the installed capacity of new energy sources in the power grid increasing year by year. The strong intermittent and fluctuating characteristics of wind and solar power output lead to a continuous widening of the daily peak-valley load difference in the power grid, placing stringent requirements on the deep peak-shaving and rapid peak-response capabilities of thermal power units. During the daytime peak hours, units require sufficient high-calorific-value raw coal to ensure full-capacity operation, while during the nighttime low-load period of deep peak-shaving, they need to stably burn low-quality coal to control fuel consumption. The coal demand under these two operating conditions is completely opposite, placing extremely high standards on the switching speed and proportioning accuracy of the raw coal bunker blending system.
[0003] Meanwhile, China is fully implementing capacity pricing policies and a spot electricity market mechanism. Power plants are required to submit their daily unit output curves to the grid in advance. If the actual power generation does not reach the submitted values, substantial deductions will be incurred. However, units that can quickly respond to dispatch instructions and reach their declared peak load can claim full capacity pricing subsidies. Participating in spot market load regulation can also generate additional revenue from peak shaving and frequency regulation ancillary services. The unit's load response speed and the flexibility of coal type switching directly determine the power plant's profitability. The old fixed coal bunkering method is no longer suitable for the operational requirements of the new electricity market.
[0004] Currently, both of the two mainstream raw coal bunker conversion schemes in the industry have inherent flaws that cannot be eradicated. At the same time, the traditional raw coal bunker system without bunkers also has inherent shortcomings. Conventional raw coal bunkers have large single-bunker volumes, with raw coal storage capacity reaching thousands of tons. When operators adjust the coal type in the bunker according to the load plan, the original coal quality replacement process in the bunker is lengthy, the coal type switching is extremely lagging, and the accuracy of blending control is low. It is very easy for low-calorific-value inferior coal in the bunker to be not completely replaced during peak periods, resulting in insufficient total calorific value entering the furnace, and the unit cannot reach the declared peak output. During deep peak shaving periods, there is too much high-calorific-value high-quality coal in the bunker, making it impossible to blend low-priced inferior coal in large quantities, resulting in high fuel costs. The contradiction between coal type supply under peak and peak shaving operating conditions has been unresolved for a long time, and the overall operational flexibility of the unit is seriously insufficient.
[0005] The proposed renovation plan for the internal partition walls of the coal silo requires welding large steel structure partitions within the confined space of the raw coal silo. Working in such a confined space presents multiple safety risks, including oxygen deficiency, coal dust explosions, and falls from heights, making construction management extremely difficult. Furthermore, the partitions are subjected to lateral pressure from the raw coal on both sides for extended periods, resulting in uneven stress distribution. After long-term operation, the equipment is highly susceptible to structural failures such as partition deformation, weld cracking, and steel plate tearing, posing significant safety hazards such as coal leakage and structural collapse. The multi-channel coal silo renovation scheme requires the installation of external small coal hoppers with a shrimp-shaped structure on the outside of the raw coal silo, along with the addition of an extended coal feeder and multiple sets of pneumatic gate valves. The entire equipment structure is complex and occupies a large amount of on-site space. The addition of equipment will significantly increase the overall load on the lower part of the raw coal silo. After the renovation is completed, the strength of the supporting steel structure and foundation load-bearing capacity of the silo must be rechecked. The overall construction period of this scheme is as long as 30 days, and the total investment in the renovation is high. The addition of two complete coal feeding and conveying systems will multiply the workload of subsequent equipment inspection, lubrication, and replacement of vulnerable parts. The coal powder flow velocity at the turning points of the external coal hopper and the extended coal drop pipe is turbulent, which is prone to coal blockage, coal accumulation, and coal slugging, requiring a large amount of additional manual clearing work.
[0006] In summary, the existing three technical solutions—traditional raw coal bunker blending mode, internal partition wall-based bunkering modification, and multi-path bunkering modification using a shrimp-shaped curve—cannot simultaneously meet multiple practical production requirements, such as simple construction, low cost, rapid and accurate coal type switching, minimal post-construction maintenance, online construction without shutting down the furnace, and no increase in bunker load. Therefore, the industry urgently needs to develop a completely new, interconnected, precise blending and conveying system for adjacent raw coal bunkers to solve the various pain points and problems existing in current thermal power plant coal blending systems. Summary of the Invention
[0007] To overcome the shortcomings of existing coal bunker renovation projects, such as long construction period, high investment, delayed coal type switching, large maintenance workload, construction hazards, and increased load on the bunker body, this invention provides a free and precise blending and conveying system for switching between coal quality in raw coal bunkers. This system enables bidirectional communication between adjacent raw coal bunkers, completes rapid switching between high and low calorific value coals within 2 minutes, precisely controls the blending ratio, requires minimal renovation, can be constructed online, is simple to operate and maintain, and has a short investment payback period.
[0008] To achieve the above objectives, the present invention provides the following technical solution: A raw coal bunker with interchangeable and precise coal quality mixing and conveying system includes two adjacent raw coal bunkers B and C, two corresponding coal feeders, and a DCS control system. It also includes a two-way gate, a screw conveyor mechanism, an electric scraper, a self-regulating coal flow device, a maintenance platform, and a coal-dredging and unblocking robot. The bidirectional gate is fixedly installed at a position 2m in diameter of the raw coal bunkers B and C respectively; the screw conveyor mechanism is located 100mm below the bidirectional gate, connecting the bottom of the raw coal bunkers B and C. The screw conveyor mechanism includes a transmission mechanism, a U-shaped trough, a U-shaped trough cover plate, a screw central shaft, and screw blades. The whole assembly is detachably connected to the raw coal bunker via a welded flange. The transmission mechanism is equipped with a variable frequency motor, which has forward and reverse rotation and stepless speed regulation functions, with a maximum coal conveying capacity of 80 tons / hour. The operating parameters are connected to the DCS control system. The U-shaped trough extends to half of the interior of raw coal bunkers B and C, covering 20% of the cross-sectional area inside the bunkers. When raw coal falls from a single bunker, half of it falls directly to the feeder below, while the other half is transported to the feeder of the adjacent bunker via the U-shaped trough. An electric scraper is installed above the U-shaped trough to scrape away the coal accumulated in the trough at regular intervals during non-interconnected coal conveying periods; a self-regulating coal flow device is installed below the gate, which is equipped with high and low limit material level monitoring equipment, and the material level signal is linked to adjust the speed of the screw conveyor mechanism. The raw coal hopper is equipped with a coal-dredging and unblocking machine to break up coal briquettes and arches in the hopper; a maintenance platform is set up between the two hoppers; the DCS control system links all equipment, and the coal type switching time is controlled within 2 minutes.
[0009] Furthermore, the bidirectional gate panel is made of 304 stainless steel, the insert plate is 25mm thick, the total valve body thickness is 400mm, and the actuator thrust is 12000kg. The gate panel is precision machined by a planer and subjected to annealing heat stress relief treatment. The inner wall smoothly transitions with the hyperbolic raw coal hopper. It is equipped with a DCS switch interface and features bidirectional sealing with zero external leakage.
[0010] Furthermore, the total length of the spiral conveying mechanism matches the measured distance between the two compartments, with a reference length of 11m; the U-shaped trough shell is made of 16Mn low-alloy high-strength steel with a wall thickness of 10mm, the U-shaped trough cover plate is 4mm thick, and the inner diameter of the trough is 550mm; the spiral central shaft is made of 16Mn steel with a diameter of 100mm; and the spiral blades are made of NM600 wear-resistant steel with a thickness of 12mm.
[0011] Furthermore, the main body of the electric scraper is made of NM600 material, and the coal scraping cycle is calibrated by on-site coal conveying tests to prevent coal accumulation and blockage inside the U-shaped chute.
[0012] Furthermore, the maintenance platform is a combined steel structure of H-beams and channel steel, which meets national load-bearing standards. It adopts a double connection of bolts and welding, and can be installed in two ways: top hoisting or ground support.
[0013] Furthermore, the working process of the coal clearing machine is as follows: the coal is vertically lowered into the bin through the coal inlet, and the air pump drives it to impact downwards to clear the coal arch; the winch reverses and pulls it back upwards, and the claw-shaped structure of the drill bit opens up and breaks up the clumps due to the resistance of the coal, thus eliminating coal blockage and coal shortage faults.
[0014] Furthermore, the system includes three operating modes: Peak load mode: Open the two-way gate of the high-quality coal bunker, close the gate of the low-quality coal bunker, the screw conveyor runs in the forward direction, and the two coal feeders supply high-calorific-value coal simultaneously. Deep peak shaving mode: Open the two-way gate of the inferior coal bunker, close the gate of the superior coal bunker, the screw conveyor runs in reverse, and the two coal feeders supply low-calorific-value economic coal simultaneously. Shutdown and coal accumulation prevention mode: The screw conveyor is shut down, the electric scraper reciprocates to scrape the coal accumulated in the U-shaped trough at regular intervals, and the self-regulating coal flow device automatically adjusts the speed when the material level is abnormal.
[0015] Furthermore, the screw conveyor adopts a modular flange disassembly and assembly structure, with the main vulnerable parts being the screw blades. The replacement cycle is 2 years, and the cost of a single replacement is less than 100,000 yuan. The total renovation cost is 60% lower than the internal partition wall compartmentation and shrimp curve multi-channel compartmentation scheme. The renovation period for a single compartment is 10 days, and it can be carried out online without shutting down the furnace. The renovation does not increase the load on the raw coal compartment.
[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. Low renovation cost and small workload: Only the bottom interconnecting spiral mechanism needs to be added. The renovation cost is 60% lower than that of the middle partition wall and shrimp multi-way compartment, and no large welding work is required inside the compartment. 2. Convenient construction and no impact on power generation: The construction period for a single silo renovation is about 10 days. It supports online construction without shutting down the furnace. The renovation does not increase the load on the raw coal silo, and there is no need to check the strength of the silo body. The amount of work in the enclosed space is minimal, and the safety risk is low. 3. Rapid coal type switching and precise blending: DCS-linked variable frequency speed regulation can complete the bidirectional switching of high and low calorific value coal in 2 minutes, and the blending ratio can be digitally and precisely controlled to solve the problem of mismatch in peak and peak coal supply; 4. Fast return on investment: The transformation cost can be fully recovered within 1-2 months after participating in power grid peak shaving and spot trading; 5. Simple system logic and strong compatibility: The original control logic of the coal feeder and pulverizing system is not modified, only an interconnection control loop is added, and the operation and maintenance threshold is low; 6. Low maintenance workload: The flange of the screw mechanism is modularly disassembled and reassembled, the only vulnerable part is the screw blade, the replacement cycle is 2 years, and the cost of a single replacement is less than 100,000 yuan; 7. Multiple anti-coal-blocking structures: Electric scraper continuously prevents coal bridging + material level adaptive speed regulation + coal-pumping robot actively breaks up arches, completely eliminating coal bridging, arching, and coal shortage faults in the bin; 8. Outstanding comprehensive economic benefits: Increasing the proportion of low-quality coal blending reduces fuel costs, enabling rapid load response to realize electricity spot market revenue, receiving full capacity price subsidies, and avoiding penalties for failing to meet performance targets. Attached Figure Description
[0017] Figure 1 This is a topological diagram of the overall structure of the raw coal bunker interconnection and blending conveying system of the present invention; Figure 2 This is a schematic diagram of the bidirectional interconnected raw coal conveying process of the present invention; Figure 3 Here is a flowchart illustrating the three operating modes of the system of this invention; Figure 4 This is a schematic cross-sectional view of the installation position of the bidirectional gate and the silo body of the present invention. Detailed Implementation
[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0019] The present invention proposes a raw coal bunker coal quality switching free and precise blending and conveying system, which includes raw coal bunkers B and C arranged adjacently, two coal feeders, a DCS control system, and also includes a bidirectional gate, a screw conveyor mechanism, an electric scraper, a self-regulating coal flow device, a maintenance platform, and a coal dredging and unblocking robot. The bidirectional gates are installed at positions with a diameter of 2m in raw coal bunkers B and C, respectively; the screw conveyor mechanism is fixed 100mm below the bidirectional gates, connecting the bottoms of the two bunkers to achieve bidirectional interconnection of raw coal. The screw conveyor consists of a transmission mechanism, a U-shaped trough, a U-shaped trough cover plate, a screw central shaft, and screw blades. The whole assembly is detachably connected to the silo body via flanges. The transmission mechanism is equipped with a variable frequency motor, which has forward and reverse rotation and stepless speed regulation functions. The maximum coal conveying capacity is 80t / h, and the speed and coal conveying parameters are connected to the DCS. The U-shaped trough extends to half the interior of each compartment, covering 20% of the cross-sectional area. When raw coal falls from a single compartment, half falls directly to the feeder below, while the other half is transported to the feeder of the adjacent compartment via the U-shaped trough, enabling simultaneous supply of a single type of coal to both compartments. An electric scraper is installed above the U-shaped trough to periodically scrape away accumulated coal and prevent coal from accumulating during non-conveying periods; a self-regulating coal flow device is installed below the gate, which is equipped with high and low limit material level monitoring equipment, and the material level is linked to adjust the screw conveyor speed to stabilize the coal feed. A steel structure maintenance platform is provided for equipment maintenance; a coal-dredging and unblocking machine is installed at the coal chute, which uses pneumatic impact and winch claw to break up arches and solve problems such as coal bridging, arching, blockage, and coal shortage. The DCS control system links the bidirectional gate, screw conveyor, electric scraper, material level equipment, and robotic rodent, and precisely controls the blending ratio through frequency conversion, keeping the coal type switching time within 2 minutes.
[0020] Specific parameters of each component: Two-way gate: door panel is made of 304 stainless steel, insert plate is 25mm thick, valve body is 400mm thick, actuator thrust is 12000kg, door panel is planed and stress-relieved annealed, inner wall smoothly transitions with hyperbolic coal hopper, no jamming or coal leakage. Screw conveyor mechanism: The total length is adapted to the actual measured distance between the two compartments (reference 11m). The U-shaped trough shell is made of 16Mn low alloy high strength steel with a wall thickness of 10mm, a cover plate thickness of 4mm, and an inner diameter of 550mm. The central shaft is made of 16Mn steel with a diameter of 100mm. The spiral blades are made of NM600 wear-resistant steel with a thickness of 12mm. Electric scraper: The scraper material is NM600, and the coal scraping cycle is calibrated by on-site coal conveying test; Maintenance platform: H-beam and channel steel load-bearing steel structure, which can be hoisted or installed on the ground support, and meets national standard load-bearing capacity; Coal-clearing and unblocking machine: Pneumatic downward impact breaks the coal arch, and the claws open to break the coal arch when the winch pulls back.
[0021] (3) System operating conditions ① Peak load operation: Raw coal bunker B stores high-calorific-value high-quality coal, and raw coal bunker C stores low-calorific-value inferior coal; the two-way gate of raw coal bunker B is opened and the gate of raw coal bunker C is closed, and the screw conveyor runs in the forward direction; half of the raw coal in raw coal bunker B falls directly to the raw coal bunker B feeder, and the other half is transported to the raw coal bunker C feeder via a U-shaped trough. Both feeders supply high-calorific-value coal, quickly increasing the unit output to meet the declared peak capacity. ② Deep peak shaving and low load operation: Close the gate of raw coal bunker B and open the gate of raw coal bunker C. The screw conveyor runs in reverse. The low-quality coal in raw coal bunker C is diverted to the coal feeder in raw coal bunker B. The two bunkers burn economical low-quality coal simultaneously, which greatly reduces fuel costs. ③ Non-interconnected conveying condition: shut down the screw conveyor mechanism, and use electric scrapers to periodically scrape the U-shaped trough to prevent coal accumulation and blockage in the trough; when the material level is abnormal, the self-regulating coal flow device will automatically adjust the speed; when blockage occurs, the mechanical rat will be activated to clear the blockage. Example
[0022] The adjacent raw coal bunkers B and C of a 600MW thermal power generating unit in China were selected as the targets for the renovation. The on-site measured straight-line distance between the centers of the two bunkers was 11m. The original complete set of weighing coal feeders were installed under the two raw coal bunkers. The original pulverizing system, boiler combustion system and DCS monitoring system of the unit were all retained. Only the interconnected blending and conveying system was added at the bottom of the raw coal bunker. The entire process adopted an online step-by-step construction plan, which did not require the entire unit to be shut down. Each day, only the low load interval of the unit was used to isolate and carry out construction in sections of a single bunker. The other raw coal bunkers maintained normal coal feeding, pulverizing and load operation, ensuring that the power plant's daytime power generation and grid dispatch were not affected by the construction.
[0023] In the early stages of construction, site surveys, load calculations, and equipment prefabrication were completed. First, the diameter of the raw coal bunker, the size of the hyperbolic coal hopper at the bottom, the vertical height difference between the discharge ports of the two bunkers, the load parameters of the load-bearing beam on the top of the bunker, and the elevation of the ground space were measured on-site. The installation position of the bidirectional gate was confirmed to be 2m above the diameter of the bunker. At this position, the coal flow velocity is slow and there are no dead corners for coal accumulation. After the gate is installed, it will not obstruct the falling of raw coal from the top. At the same time, the installation space of the screw conveyor mechanism was calculated to determine that a 100mm installation and maintenance gap should be reserved between the lower edge of the gate and the upper surface of the screw conveyor mechanism to avoid the problem of the gate directly impacting the screw blades and causing accelerated wear. Based on the site dimensions, the entire screw conveyor mechanism, bidirectional gate, and steel structure maintenance platform were prefabricated in the factory. All equipment underwent water pressure, sealing, and no-load rotation tests before leaving the factory to verify the zero leakage performance of the gate, the stability of the screw mechanism at full load of 80t / h, and the forward and reverse speed regulation accuracy of the variable frequency motor. Factory prefabrication can significantly reduce the time spent on high-altitude operations on site and reduce the amount of on-site welding and assembly work.
[0024] On-site step-by-step installation operation, first phase: Circular installation holes were drilled at a height of 2m in raw coal bunkers B and C. The edges of the holes were ground smooth to remove burrs. The prefabricated bidirectional gate was hoisted into place as a whole and firmly connected to the bunker wall using a ring-shaped welded flange. After welding, non-destructive testing was performed to eliminate welding cracks and defects. The inner door panels of the gate were aligned and finely adjusted to ensure a smooth transition between the inner curved surface of the valve body and the inner wall of the hyperbolic coal hopper of the raw coal bunker, without any protrusions or steps, to avoid coal dust accumulation on the wall. After the mechanical installation was completed, control cables were laid, and the bidirectional gate actuator signals were connected to the unit's original DCS control system. A separate control screen was added to realize remote switching, status feedback, and fault alarm functions. The entire process of installing, welding, testing, wiring, and debugging a single gate was completed within 2 days.
[0025] The second stage involves hoisting and assembling the screw conveyor mechanism. The prefabricated U-shaped screw conveyor mechanism is hoisted to a reserved position 100mm below the two gate valves. The flanges at both ends are bolted to the bottom discharge flanges of raw coal bunkers B and C, respectively. High-temperature and wear-resistant sealing gaskets are installed between the flanges to prevent coal dust leakage. The level of the U-shaped trough is adjusted to ensure that there is no coal accumulation on one side during raw coal conveying. The two ends of the U-shaped trough extend into 1 / 2 of the area inside the raw coal bunker, covering 20% of the cross-sectional area inside the bunker, to achieve natural diversion of raw coal. The frequency conversion drive mechanism is installed and connected to the 380V power supply and DCS analog signal line. The 0-50Hz frequency conversion range is calibrated, corresponding to the 0-80t / h raw coal conveying range. The relationship between coal flow rate and screw speed at different frequencies is recorded and entered into the DCS control database. The detachable U-shaped trough cover is sealed, and a daily maintenance observation port is reserved.
[0026] Phase Three: Installation and Commissioning of Supporting Auxiliary Equipment An electric scraper is fixed to the bracket above the U-shaped trough cover plate. The scraper body is made of NM600 wear-resistant steel plate and is equipped with an electric push rod to drive the reciprocating scraping action. A 72-hour continuous scraping test was conducted based on the on-site coal viscosity and coal powder moisture content to calibrate the optimal scraping interval. A self-regulating coal flow device is installed on the lower part of the silo wall of the gate. The high and low limit material level switches are arranged vertically in layers. The material level analog signal is connected to the DCS logic block, and a linkage program is written. When the material level in the silo reaches the high limit, the operating frequency of the screw conveyor is automatically reduced, and when the material level drops to the low limit, the speed is automatically increased to stabilize the total amount of coal fed by the two coal feeders. An H-type elevator is hoisted in the middle area between the two silos. The maintenance platform is a combination of steel profiles and channel steel. The platform railings, anti-slip steps, and maintenance ladders are installed simultaneously and are fixed by bolts and welding. The platform's load-bearing capacity meets the standards for single-person maintenance operations with tools. Quick installation interfaces for coal-clearing and unblocking robotic mice are reserved at the coal drop outlets of the two raw coal bunkers. The pipelines for the matching air pump and winch are laid to complete the debugging of the robotic mice's downward impact and pullback arch-breaking actions.
[0027] Phase 4: DCS control logic configuration and system integration testing: Three types of automatic operation logic programs were added to the original control system of the unit: peak high load coal blending logic, deep peak shaving low load coal blending logic, and automatic shutdown to prevent coal blockage. At the same time, coal blockage alarm and remote one-button start control programs for the robotic mouse were added. During the joint commissioning, the load increase and decrease commands of the power grid dispatch were simulated, and high and low calorific value coal types were switched multiple times. The timing was confirmed to ensure that the complete coal type switching time was stably controlled in the range of 110s to 120s, which meets the 2-minute rapid response requirement. Various abnormal working conditions such as high material level, low material level, and coal blockage in the bin were simulated to verify the reliability of the linkage action of the self-regulating coal flow device, electric scraper, and coal clearing robotic mouse.
[0028] The entire system was constructed in 10 days per compartment, and after all equipment was installed and commissioned, it was put into commercial operation, with operational data continuously tracked for 6 months. During peak output phases, the unit can rapidly increase the overall calorific value of the coal fed into the furnace, ensuring stable output that meets the grid's declared peak value without any capacity pricing deductions. Under deep peak-shaving conditions at night, the proportion of low-calorific-value, inferior coal blending increases by 13%, significantly reducing the coal cost per unit of electricity generated. The frequency of coal bridging, arching, and coal shortage faults in the coal storage area decreases by 92% compared to before the upgrade, eliminating the need for 24-hour manual coal clearing. The total cost of the entire upgrade is 61% lower than the multi-channel storage scheme based on the shrimp curve. After deducting equipment and construction costs, the entire upgrade investment is fully recovered by the fuel cost savings from blending inferior coal and the benefits of spot peak-shaving on the 36th day of operation. The wear of the spiral blades has not reached the replacement threshold after two years of continuous operation, resulting in a much lower equipment maintenance workload than the traditional multi-channel storage upgrade scheme. There is no need to modify the original control logic of the coal feeder and coal mill, ensuring stable and reliable unit operation and fully adapting to the current multiple operational needs of the new electricity market, including peak-shaving, spot trading, and capacity pricing.
[0029] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications or equivalent substitutions based on the technical solutions of the present invention without departing from the core ideas of the present invention shall fall within the protection scope of the present invention.
Claims
1. A raw coal bunker with interchangeable and precise coal quality blending and conveying system, comprising adjacent raw coal bunkers B and C, two corresponding coal feeders, and a DCS control system, characterized in that: It also includes a two-way gate, a screw conveyor mechanism, an electric scraper, a self-regulating coal flow device, a maintenance platform, and a coal-dredging and unblocking robot. The bidirectional gate is fixedly installed at a position 2m in diameter of the raw coal bunkers B and C respectively; the screw conveyor mechanism is located 100mm below the bidirectional gate, connecting the bottom of the raw coal bunkers B and C. The screw conveyor mechanism includes a transmission mechanism, a U-shaped trough, a U-shaped trough cover plate, a screw central shaft, and screw blades. The whole assembly is detachably connected to the raw coal bunker via a welded flange. The transmission mechanism is equipped with a variable frequency motor, which has forward and reverse rotation and stepless speed regulation functions, with a maximum coal conveying capacity of 80 tons / hour. The operating parameters are connected to the DCS control system. The U-shaped trough extends to half of the interior of raw coal bunkers B and C, covering 20% of the cross-sectional area inside the bunkers. When raw coal falls from a single bunker, half of it falls directly to the feeder below, while the other half is transported to the feeder of the adjacent bunker via the U-shaped trough. An electric scraper is installed above the U-shaped trough to scrape away the coal accumulated in the trough at regular intervals during non-interconnected coal conveying periods; a self-regulating coal flow device is installed below the gate, which is equipped with high and low limit material level monitoring equipment, and the material level signal is linked to adjust the speed of the screw conveyor mechanism. The raw coal hopper is equipped with a coal-dredging and unblocking machine to break up coal briquettes and arches in the hopper; a maintenance platform is set up between the two hoppers; the DCS control system links all equipment, and the coal type switching time is controlled within 2 minutes.
2. The raw coal bunker coal quality switching and precise blending and conveying system according to claim 1, characterized in that: The bidirectional gate is made of 304 stainless steel, with a plate thickness of 25mm and a total valve body thickness of 400mm. The actuator thrust is 12000kg. The gate is precision machined by a planer and subjected to annealing and heat stress relief treatment. The inner wall smoothly transitions with the hyperbolic raw coal hopper. It is equipped with a DCS switch interface and features bidirectional sealing with zero external leakage.
3. The raw coal bunker coal quality switching and precise blending and conveying system according to claim 1, characterized in that: The total length of the spiral conveyor mechanism matches the measured distance between the two compartments, with a reference length of 11m; the U-shaped trough shell is made of 16Mn low-alloy high-strength steel with a wall thickness of 10mm, the U-shaped trough cover plate is 4mm thick, and the inner diameter of the trough is 550mm; the spiral central shaft is made of 16Mn steel with a diameter of 100mm; the spiral blades are made of NM600 wear-resistant steel with a thickness of 12mm.
4. The raw coal bunker coal quality switching and precise blending and conveying system according to claim 1, characterized in that: The electric scraper blade body is made of NM600 material, and the coal scraping cycle is calibrated by on-site coal conveying tests to prevent coal accumulation and blockage inside the U-shaped chute.
5. The raw coal bunker coal quality switching and precise blending and conveying system according to claim 1, characterized in that: The maintenance platform is a combined steel structure of H-beams and channel steel, which meets national load-bearing standards. It adopts a double connection of bolts and welding, and can be installed in two ways: top hoisting or ground support.
6. The raw coal bunker coal quality switching and precise blending and conveying system according to claim 1, characterized in that: The working process of the coal clearing machine is as follows: the coal is vertically lowered into the bin through the coal inlet, and the air pump drives it to impact downwards to clear the coal arch; the winch reverses and pulls it back upwards, and the claw-shaped structure of the drill bit opens up and breaks up the clumps due to the resistance of the coal, thus eliminating coal blockage and coal shortage faults.
7. The raw coal bunker coal quality switching and precise blending and conveying system according to claim 1, characterized in that: The system includes three operating modes: Peak load mode: Open the two-way gate of the high-quality coal bunker, close the gate of the low-quality coal bunker, the screw conveyor runs in the forward direction, and the two coal feeders supply high-calorific-value coal simultaneously. Deep peak shaving mode: Open the two-way gate of the inferior coal bunker, close the gate of the superior coal bunker, the screw conveyor runs in reverse, and the two coal feeders supply low-calorific-value economic coal simultaneously. Shutdown and coal accumulation prevention mode: The screw conveyor is shut down, the electric scraper reciprocates to scrape the coal accumulated in the U-shaped trough at regular intervals, and the self-regulating coal flow device automatically adjusts the speed when the material level is abnormal.
8. The raw coal bunker coal quality switching and precise blending and conveying system according to claim 1, characterized in that: The screw conveyor adopts a modular flange disassembly and assembly structure. The main vulnerable part is the screw blade, with a replacement cycle of 2 years and a single replacement cost of less than 100,000 yuan. The total renovation cost is 60% lower than the internal partition wall compartment and shrimp curve multi-channel compartment scheme. The renovation period for a single compartment is 10 days. It can be carried out online without shutting down the furnace and does not increase the load on the raw coal silo after the renovation.