Alternating double-tank positive pressure dense-phase pulse conveying system for pulverized coal

Abstract

The utility model discloses a kind of double-tank alternate coal dust positive pressure dense-phase pulse conveying systems, belong to coal dust conveying technical field, including first coal dust bin, the first coal dust bin side is connected with nitrogen buffer tank, the first coal dust bin lower end is connected with first sending tank and second sending tank side by side, the outlet junction of first sending tank and second sending tank is provided with three-way diverter valve, time sequence controller and pressure sensor are provided on the three-way diverter valve, and the pressure release port of first sending tank and second sending tank is connected to second coal dust bin respectively.The utility model is used to solve the technical problem that the existing coal dust conveying system cannot ensure the continuity of powder supply.

Description

Technical Field

[0001] This utility model belongs to the field of pulverized coal conveying technology, specifically relating to a dual-tank alternating pulverized coal positive pressure dense phase pulse conveying system. Background Technology

[0002] Pneumatic conveying of pulverized coal is a core technological process in modern coal chemical, thermal power generation, and blast furnace ironmaking industries. Its core objective is to stably, continuously, and efficiently transport qualified pulverized coal to reaction units (such as gasifiers, boilers, and blast furnaces). Currently, the mainstream pneumatic conveying methods in industrial applications mainly include mechanical conveying, dilute phase conveying, and dense phase conveying.

[0003] Mechanical conveying (such as screw conveyors and scraper conveyors) propels pulverized coal forward within a closed trough using rotating screw blades or a circulating scraper chain. However, over long distances, pulverized coal leakage is prone to occur at the shaft end and casing joints, causing environmental pollution and material loss. Dilute-phase pneumatic conveying uses high-speed airflow (typically >18-20 m / s) to suspend and blow pulverized coal within the pipeline. The system structure is simple, typically consisting of a transmitter, fan, conveying pipeline, and receiving bin. However, maintaining high airflow velocity requires enormous power, resulting in high energy consumption per unit volume (Nm³). 3 The gas / ton coal ratio is extremely high. Dense phase pneumatic conveying (single-tank pulse type) has been developed to overcome the shortcomings of dilute phase conveying and has become the mainstream choice for medium and high pressure conveying. It uses a single sending tank. Its working cycle is as follows: 1) Loading at atmospheric pressure; 2) Closing the loading valve and pressurizing the tank to the working pressure; 3) Opening the outlet valve and using compressed gas (such as nitrogen) to push the high-concentration pulverized coal out in a plug flow or pulse form (flow velocity usually <8-12m / s); 4) After the pulverized coal in the tank is emptied, depressurization is performed; 5) Repeat step 1). The control system operates in this sequence. However, its inherent "loading-pressurization-sending-depressurization" working cycle results in an intermittent conveying process. During the loading and pressurization stages, there is no downstream material flow, which seriously affects the stability of the supply to subsequent reaction units. In addition, the effective conveying time usually accounts for only about 65%, with a large amount of time wasted on auxiliary processes, making it difficult to meet the capacity requirements of large-scale continuous production.

[0004] Chinese patent CN102212628A discloses a method and system for supplying standby pulverized coal for blast furnace pulverized coal injection. By adding one or two pulverizing systems and conveying pipelines, and utilizing gas pressurization equipment, pulverized coal can be transferred from other blast furnace injection stations when there is a shortage, ensuring continuous supply. The system has a simple structure and low initial investment. However, its design objective is "intermittent supplementation," meaning it starts when the main system fails, performing intermittent batch delivery in single tanks. Its continuity guarantee is for downstream blast furnaces (preventing supply interruptions), not for the continuity of its own conveying process. Therefore, although the system has two tanks, its operation follows a simple "one in use, one on standby" logic. When one tank is sending coal, the other tank is simply on standby, only switching to the standby tank after the sending tank is completely emptied and all preparation processes are completed. This results in a significant delivery gap. Utility Model Content

[0005] In order to overcome the shortcomings of the prior art, the purpose of this utility model is to provide a dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal, so as to solve the technical problem that the existing pulverized coal conveying system cannot ensure the continuity of coal supply.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal, comprising a first pulverized coal silo, a nitrogen buffer tank connected to one side of the first pulverized coal silo, and a first and second sending tank connected in parallel at the lower end of the first pulverized coal silo. A three-way diverting valve is installed at the junction of the outlets of the first and second sending tanks, and the three-way diverting valve is equipped with a timing controller and a pressure sensor. The pressure relief ports of the first and second sending tanks are respectively connected to the second pulverized coal silo. The pressure sensor monitors the pressure changes in the conveying pipeline in real time and feeds the data back to the timing controller. The controller dynamically adjusts the inlet valve of the nitrogen buffer tank or the fluidizing gas volume of the sending tank through a PID algorithm to ensure that the system pressure is always maintained within the optimal conveying range, thereby effectively preventing conveying instability caused by pipeline blockage or pressure fluctuations. Preferably, residual pressure recovery pipelines are installed at the top of the first pulverized coal silo, the first sending tank, and the pressure relief port of the first sending tank. The addition of residual pressure recovery pipelines connected to the top filter of the pulverized coal silo enables the recovery and reuse of high-pressure nitrogen.

[0007] Preferably, a Venturi ejector is installed on the residual pressure recovery pipeline. The Venturi ejector can recover more than 30% of the high-pressure nitrogen, effectively reducing nitrogen consumption and improving energy utilization efficiency.

[0008] Preferably, the pulverized coal silo filter adopts a pulse backflushing structure and is equipped with a differential pressure alarm device. The filtration area of ​​the pulverized coal silo filter can reach 135㎡, which can effectively improve the filtration efficiency.

[0009] Preferably, the differential pressure alarm device has a differential pressure ≥ 0.004 MPa. When the differential pressure is ≥ 0.004 MPa, it automatically backflushes to ensure the normal operation of the pulverized coal silo filter.

[0010] Preferably, the pressure relief ports of the first and second sending tanks are equipped with air knife valves.

[0011] Furthermore, the air knife valve adopts a fast-cut-off type with a response speed of 0.1 seconds, which can cut off the airflow in time and prevent the blockage from expanding further.

[0012] Preferably, the inner wall of the conveying pipe of the conveying system has a spiral guide groove structure. Referring to the principle of airflow rotation, this causes the pulverized coal to rotate and flow within the pipe, reducing material accumulation.

[0013] Preferably, a cloth bag is provided on the top of the second pulverized coal silo.

[0014] Preferably, the nitrogen buffer tank is equipped with a PID pressure regulating module.

[0015] Preferably, the pressure of the PID pressure regulating module is ±0.02MPa.

[0016] Further preferably, the volume of the first or second sending tank is based on the pulverized coal silo (170m³). 3 The design is matched to the capacity of the instrument, with an effective volume of 85m³. 3 The tank body adopts a composite structure of Q345R steel and ceramic lining, with a pressure resistance of up to 1.0MPa. This structure not only enhances the tank's pressure resistance but also improves its wear resistance and extends its service life. The ceramic lining extends the tank's lifespan to 5 years, while carbon steel tanks need to be replaced on average every 2 years, reducing equipment replacement costs and maintenance workload.

[0017] Further preferred configuration is 13m 3 The nitrogen buffer tank, equipped with a PID pressure regulating module, can control the outlet pressure fluctuation within ±0.02MPa, ensuring a stable supply of nitrogen pressure.

[0018] In a further preferred embodiment, pressure sensors are installed on the first or second sending tank, connecting pipeline, and pulverized coal silo filter to collect system pressure data in real time. The timing controller enables precise switching between the three stages of pressurization, sending, and depressurization, ensuring the stability and efficiency of system operation.

[0019] Compared with the prior art, the present invention has the following beneficial effects: This invention provides a dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal. Through the coordinated operation of a first pulverized coal silo, a nitrogen buffer tank, a first and second sending tank arranged in parallel, a three-way diverting valve, a timing controller, and a pressure sensor, a system capable of continuous and uninterrupted pulverized coal supply is constructed. From a principle perspective, the parallel design of the dual tanks allows one sending tank to be in a loading or preparation state while the other is performing the conveying task. The rapid switching function of the three-way diverting valve ensures that the material conveying process is not interrupted. This solves the problem of intermittent conveying caused by the loading cycle in traditional single-tank systems. Furthermore, by adopting a positive pressure dense phase pulse conveying method, compared with traditional dilute phase conveying, the dense phase pulse conveying has a higher solid-to-gas ratio and a lower conveying speed, greatly reducing pipeline wear and pulverized coal breakage, while significantly reducing power consumption and achieving a highly efficient and energy-saving conveying effect. The nitrogen buffer tank provides a stable gas source, enabling the pulverized coal to be conveyed at a low speed in the pipeline in an alternating mode of material plug-gas plug, greatly reducing the material breakage rate and pipeline wear. The introduction of a timing controller and pressure sensors enables intelligent management of the conveying process. The system can dynamically adjust conveying parameters based on real-time pressure data, ensuring conveying stability and reliability. The design of connecting the pressure relief port to the second pulverized coal bunker achieves dual recovery and utilization of pressure and materials, avoiding environmental pollution and improving system energy efficiency, meeting the requirements of modern industry for green production.

[0020] Furthermore, residual pressure recovery pipelines are installed at the top of the pulverized coal silo and the pressure relief port of the sending tank. The core principle behind this is the cascade utilization of energy. After high-pressure transmission, inert gases (usually nitrogen) with high pressure remain in the sending tank and pipelines. These gases carry considerable pressure energy. Directly releasing them into the atmosphere would not only waste energy but could also generate noise and dust emissions due to instantaneous pressure relief. By using residual pressure recovery pipelines, these pressurized gases are guided to the second pulverized coal silo or returned to the system's starting point, achieving internal recycling of pressure energy. This effectively reduces the system's pressure and flow requirements from an external nitrogen source, thereby reducing the energy consumption required for nitrogen compression.

[0021] Furthermore, the Venturi ejector. Its working principle is based on the Venturi effect: when a high-pressure gas flow passes through a reducing pipe, a negative pressure is generated at the throat, thereby drawing in and mixing with another low-pressure fluid. In this application, the Venturi ejector uses the high-pressure gas flow in the recovery pipeline as a power source to generate a vacuum suction force, which can more efficiently draw residual coal powder or low-pressure gas from the pressure relief port of the delivery tank to the second coal silo or a designated recovery point, enhancing the reliability and efficiency of the residual pressure recovery system. It avoids the accumulation of residual coal powder in dead zones, and its design with no moving parts ensures low maintenance costs and high operational reliability.

[0022] Furthermore, the pulverized coal silo filter is designed with a pulse backflushing structure and equipped with a differential pressure alarm device. The principle is that during the feeding or pressure balancing process of the pulverized coal silo, the gas inside the silo needs to pass through the filter to prevent dust from escaping. However, pulverized coal gradually adheres to the surface of the filter media, causing filter blockage. The pulse backflushing structure, through a time-controlled solenoid valve, instantaneously injects high-pressure compressed air to backflush the filter, causing the dust adhering to it to fall off, thereby achieving online self-cleaning of the filter and ensuring its continuous and stable airflow capacity. The differential pressure alarm device prevents abnormal pressure increases inside the silo due to complete filter blockage, which could lead to system shutdown, filter damage, or even overpressure safety risks, realizing a shift from reactive maintenance to early warning maintenance.

[0023] Furthermore, the differential pressure alarm value (≥0.004MPa) setting can issue a warning before the filter performance significantly degrades but before it completely fails. This provides ample time for planned maintenance and greatly avoids unplanned downtime.

[0024] Furthermore, an air knife valve is installed on the pressure relief port of the sending tank. Compared with traditional valves, the air knife valve uses high-pressure airflow to form an air blade, which can instantly and completely cut off the material flow. Its principle lies in the strong cleaning effect of high-speed airflow on materials, which is particularly suitable for powdery materials such as coal powder that are easy to adhere to and leave residues. When the sending tank completes the conveying and needs to be depressurized, the rapid and tight shut-off characteristics of the air knife valve ensure that coal powder backflow or leakage is effectively prevented when switching tanks, ensuring the cleanliness and smoothness of the dual-tank alternation process, reducing crosstalk and pressure loss caused by valves not closing tightly, thereby maintaining the system's working efficiency and stability.

[0025] Furthermore, the spiral guide groove structure on the inner wall of the conveying pipeline serves two purposes: firstly, it generates a continuous upward force on the bottom particles, preventing them from settling; secondly, it enhances the entrainment of solid particles by the gas, resulting in smoother operation of the feed plug and reduced conveying resistance. Therefore, this structure effectively reduces the power required for conveying and further mitigates erosion of the pipeline, especially in easily worn areas such as elbows, extending the service life of the equipment.

[0026] Furthermore, a filter bag is installed at the top of the second pulverized coal silo. As the receiving point for depressurized and recovered materials, the pressure inside the second pulverized coal silo fluctuates slightly when receiving pressurized gas and a small amount of dust. The filter bag at the top serves as a simple and efficient exhaust and dust removal device, allowing gas to escape smoothly while simultaneously capturing entrained fine coal particles, preventing them from being released into the atmosphere. This not only meets environmental protection requirements and achieves closed-loop, dust-free operation of the entire system, but also ensures the stable release of pressure within the second pulverized coal silo itself, preventing gas accumulation and overpressure within the silo.

[0027] Furthermore, by integrating a PID pressure regulating module, closed-loop automatic control of the nitrogen buffer tank outlet pressure is achieved. The PID controller can perform a combination of proportional, integral, and derivative operations based on the deviation between the set value and the actual value, quickly and accurately adjusting the opening of the pressure regulating valve to resist external disturbances, such as fluctuations in gas consumption, and maintain a high degree of pressure stability.

[0028] Furthermore, limiting pressure fluctuations to an extremely narrow range of ±0.02 MPa is crucial for the stable operation of the system. In a dense-phase system where pressure differential is the driving force for transport, even minute fluctuations in the power source pressure are amplified, affecting the formation and movement of the feed plugs, and consequently impacting the stability of the transport and the mixing ratio. Extremely high pressure stability is the cornerstone of achieving precise, reliable, and repeatable transport. Attached Figure Description

[0029] Figure 1 This is a structural diagram of the dual-tank alternating pulverized coal positive pressure dense phase pulse conveying system of this utility model.

[0030] Wherein: 1-First pulverized coal bin; 2-Pulverized coal bin filter; 3-Nitrogen buffer tank; 4-First sending tank; 5-Second sending tank; 6-Second pulverized coal bin; 7-Bag filter. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the utility model described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments: Example 1 like Figure 1 As shown, the dual-tank alternating pulverized coal positive pressure dense phase pulse conveying system of this embodiment 1 is applied to a large-scale coal gasification unit to continuously supply pulverized coal to the gasifier.

[0034] The dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal includes: a first pulverized coal silo 1 and a second pulverized coal silo 6, with a volume of 170m³ for both silos. 3 The top of the first pulverized coal silo 1 is equipped with a pulverized coal silo filter 2. The bottom of the first pulverized coal silo 1 is connected in parallel to a first sending tank 4 and a second sending tank 5. The effective volume of each of the first sending tanks 4 and 5 is 85 m³. 3 The capacity is matched to that of the first pulverized coal silo 1 and the second pulverized coal silo 6. The tank structure of the first sending tank 4 and the second sending tank 5 adopts a composite structure of Q345R steel plate and ceramic lining. The design pressure is 1.0 MPa, and the normal working pressure is 0.85 MPa. A nitrogen buffer tank 3 with a volume of 13 m³ is connected to one side of the first pulverized coal silo 1. 3 The outlet integrates a PID pressure regulating module to control outlet pressure fluctuations within ±0.02MPa. The conveying pipeline of the dual-tank alternating pulverized coal positive pressure dense phase pulse conveying system has a diameter of DN200 and a designed flow velocity of 18-22m / s. Spiral guide grooves are machined on the inner wall to prevent pulverized coal accumulation. A three-way reversing valve is installed at the junction of the outlets of the first sending tank 4 and the second sending tank 5 to achieve seamless switching between sending from the first sending tank 4 and feeding from the second sending tank 5, ensuring the continuity of the conveying process. Air knife valves are installed at the pressure relief ports of the first sending tank 4 and the second sending tank 5, with a response speed ≤0.1 seconds, for rapid shut-off. Residual pressure recovery pipelines are installed at the top of the first pulverized coal silo 1 and at the pressure relief ports of the first sending tank 4 and the second sending tank 5. During the sending phase, the pressure is maintained between 0.6-0.8MPa to ensure stable pulverized coal conveying; during the pressure relief phase, residual pressure above 0.3MPa is introduced into the pulverized coal buffer tank 3 to achieve energy recovery. A Venturi ejector is installed on the residual pressure recovery pipeline. A timing controller is installed on the residual pressure recovery pipeline to control the precise switching of the three stages of "pressurization-emission-depressurization". Pressure sensors are installed on the first emission tank 4 and the second emission tank 5, the connecting pipeline and the pulverized coal silo filter 2 to collect pressure data in real time. The pulverized coal silo filter 2 is equipped with a differential pressure alarm device with a set value of ≥0.004MPa, which triggers automatic backflushing. The differential pressure alarm device is also equipped with a fault self-diagnosis system, which compares the pressure curves of the first emission tank 4 and the first emission tank 5 in real time. When the deviation is >10%, an alarm is triggered to promptly detect and handle system faults. The second pulverized coal silo 6 serves as a receiving device, and a filter bag 7 is installed on the top for dust removal.

[0035] The dual-tank alternating conveying mode of this invention increases the effective conveying time ratio from 65% to 92%, a significant improvement compared to other models. The actual production rate of the designed capacity of 180t / h is ≥98%, meeting the needs of large-scale continuous production. Energy consumption is reduced: nitrogen consumption is reduced from 0.8Nm³. 3 / t decreased to 0.65Nm 3 / t, a reduction of 18.75%, significantly lowering production costs. Enhanced safety: The filter bag breakage rate decreased from 2.1 times / thousand hours in the original system to 0.3 times / thousand hours, effectively improving the system's safety and stability.

[0036] The working principle of this utility model dual-tank alternating pulverized coal positive pressure dense phase pulse conveying system: Phase 1: First sending tank 4 sends - Second sending tank 5 prepares (0-180 seconds) First sending tank 4 (sending state): After being filled with pulverized coal and pressurized to 0.75MPa, the outlet valve is opened. Driven by high-pressure nitrogen, the pulverized coal enters the conveying pipeline through the three-way reversing valve and is finally sent to the second pulverized coal silo 6. The spiral guide channel inside the pipeline causes the pulverized coal to form a rotating flow and core flow, which greatly reduces the accumulation of material on the pipe wall.

[0037] Second sending tank 5 (ready state): At this time, the three-way reversing valve cuts off the passage of the second sending tank 5. The second sending tank 5 is undergoing the process of depressurization, filling with new pulverized coal, and repressurization in preparation for its next sending operation.

[0038] Nitrogen supply: The nitrogen buffer tank 3 provides an extremely stable gas source for the pressurization and delivery of the first sending tank 4 and the second sending tank 5 through the PID pressure regulating module.

[0039] Energy recovery: When the second sending tank 5 is depressurized, the high-pressure nitrogen gas above 0.3MPa is quickly cut off by the air knife valve and enters the residual pressure recovery pipeline. It is recovered by the Venturi ejector and introduced into the coal powder silo filter 2 at the top of the first coal powder silo 1 for backflushing or pressure replenishment.

[0040] Phase Two: Switching and Alternating (181-210 seconds) Intelligent switching: When the timing controller detects that the pulverized coal in the first sending tank 4 is about to be emptied (judged by pressure sensor data), it immediately commands the three-way reversing valve to switch in a very short time (<30 seconds) to redirect the pulverized coal flow from the first sending tank 4 to the ready second sending tank 5.

[0041] Seamless connection: The pressure of the second sending tank 5 has fully reached the sending requirements, and powder feeding will start immediately, achieving seamless connection and continuous conveying.

[0042] Phase 3: Second sending tank 5 sends - First sending tank 4 prepares (211-390 seconds) The second sending tank 5 has entered the sending state.

[0043] The first sending tank 4 enters the preparation state for depressurization, loading, and pressurization, and recovers its depressurized residual gas.

[0044] This cycle repeats continuously, allowing for alternating and continuous transport between the two tanks.

[0045] This utility model provides an application for a coal gasification project: Equipment parameters: The first sending tank 4 and the second sending tank have a specification of Φ3000×12000mm and a working pressure of 0.85MPa; the conveying pipeline has a diameter of DN200 and a flow velocity controlled at 18-22m / s.

[0046] Operating procedures: Phase 1 (0-30s): First feeding tank 4 is pressurized to 0.75MPa, and second feeding tank 5 receives 25m of feed. 3 .

[0047] Phase 2 (31-210s): The first sending tank 4 begins sending pulverized coal, and the second sending tank 5 completes feeding and begins pressurization.

[0048] Phase 3 (211-240s): The first sending tank 4 is depressurized to 0.15MPa, and the second sending tank 5 begins sending.

[0049] Actual measured data: The conveying capacity reached 182.3 t / h, exceeding the design requirements; nitrogen consumption was 0.63 Nm³. 3 / t, lower than the expected target; the differential pressure of the pulverized coal silo filter 2 is stable at 0.002-0.003MPa, meeting the control requirements.

[0050] Special operating condition handling: When a sudden increase in pipeline pressure > 0.9 MPa is detected, the system automatically switches to emergency mode. Immediately close the outlet valve of the current delivery tank to prevent pulverized coal from continuing to enter and block the pipeline; initiate the backup pipeline purging procedure to clear the blockage; simultaneously, a blockage location indicator will pop up on the HMI interface for timely fault handling by personnel.

[0051] The above content is only for illustrating the technical concept of this utility model and should not be construed as limiting the scope of protection of this utility model. Any modifications made to the technical solution based on the technical concept proposed in this utility model shall fall within the scope of protection of the claims of this utility model.

Claims

1. A dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal, characterized in that, It includes a first pulverized coal silo (1), a nitrogen buffer tank (3) connected to one side of the first pulverized coal silo (1), a first sending tank (4) and a second sending tank (5) connected in parallel at the lower end of the first pulverized coal silo (1), a three-way diverting valve is provided at the junction of the outlets of the first sending tank (4) and the second sending tank (5), the three-way diverting valve is provided with a timing controller and a pressure sensor, and the pressure relief ports of the first sending tank (4) and the second sending tank (5) are respectively connected to the second pulverized coal silo (6).

2. The dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal according to claim 1, characterized in that, Residual pressure recovery pipelines are installed at the top of the first pulverized coal silo (1), the pressure relief ports of the first sending tank (4) and the second sending tank (5).

3. The dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal according to claim 2, characterized in that, A Venturi ejector is installed on the residual pressure recovery pipeline.

4. The dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal according to claim 1, characterized in that, The first coal powder silo (1) is equipped with a coal powder silo filter (2) on top. The coal powder silo filter (2) adopts a pulse backflushing structure and is equipped with a differential pressure alarm device.

5. A dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal according to claim 4, characterized in that, The differential pressure alarm device has a differential pressure ≥ 0.004 MPa.

6. The dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal according to claim 1, characterized in that, Air knife valves are provided on the pressure relief ports of the first sending tank (4) and the second sending tank (5).

7. A dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal according to claim 1, characterized in that, The inner wall of the conveying pipe of the conveying system is a spiral guide groove structure.

8. A dual-tank alternating pulverized coal positive pressure dense phase pulse conveying system according to claim 1, characterized in that, The top of the second pulverized coal silo (6) is provided with a cloth bag (7).

9. A dual-tank alternating positive pressure dense phase pulse conveying system for pulverized coal according to claim 1, characterized in that, The nitrogen buffer tank (3) is equipped with a PID pressure regulating module.

10. A dual-tank alternating pulverized coal positive pressure dense phase pulse conveying system according to claim 9, characterized in that, The pressure of the PID pressure regulating module is ±0.02MPa.

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