A differential pressure detection system for a coal mill

Abstract

The utility model provides a kind of coal mill differential pressure detection system, it is related to coal mill monitoring field, comprising: sealing air supply mechanism, primary air supply pipe, the output end of primary air supply pipe is connected with the primary air inlet of coal mill;First detector, two detection ends of first detector are connected with air supply main pipe and primary air supply pipe respectively, and first detector can detect the pressure difference of air supply main pipe and primary air supply pipe;Second detector, two detection ends of second detector are connected with mill base air supply subpipe and primary air supply pipe respectively, and second detector can detect the pressure difference of mill base air supply subpipe and primary air supply pipe, the utility model discloses a kind of coal mill differential pressure detection system, the utility model is additionally provided with differential pressure detector to realize the additional monitoring of coal mill, improve the comprehensiveness of coal mill sealing air and primary air monitoring.

Description

Technical Field

[0001] This utility model relates to the field of coal mill monitoring, and in particular to a coal mill differential pressure detection system. Background Technology

[0002] The coal mill is a core piece of equipment in the pulverizing system of a coal-fired power plant, and its operational stability directly affects the safety and economy of the unit. During the operation of the coal mill, the pressure balance between the sealing air system and the primary air system is crucial. The sealing air prevents pulverized coal from entering the grinding rollers and prevents it from leaking out through the tie rods and base components, while the primary air is responsible for conveying and drying the pulverized coal. Insufficient sealing air pressure can lead to pulverized coal leakage, accelerated equipment wear, and even bearing damage; an imbalance in the pressure difference between the sealing air and the primary air can trigger serious accidents such as backfire and deflagration.

[0003] In actual production, coal mills need to maintain a pressure difference of ≥2 kPa between the sealing air and primary air during normal operation. Current technology only monitors the pressure difference between the sealing air main pipe and the primary air, but no measuring points are designed for the downstream branches. Especially when leakage is severe in one branch, it affects the pressure in other branches, compromising safety. For units that have been in operation for a long time, although the monitored pressure difference is ≥2 kPa, the actual pressure difference in the sealing air branches can decrease due to various factors, particularly at the separator. Even with butterfly valves installed on the branches, the adjustment parameters are not clearly defined, sometimes leading to insufficient sealing airflow and simultaneous operation of the sealing fans, significantly increasing their power consumption. Utility Model Content

[0004] The purpose of this invention is to provide a coal mill differential pressure detection system to improve the comprehensiveness of monitoring the differential pressure of the coal mill sealing air and primary air.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a coal mill differential pressure detection system, comprising: a sealed air supply mechanism, the sealed air supply mechanism including a main air supply pipe and a base air supply sub-pipe, the output end of the main air supply pipe being connected to the input end of the base air supply sub-pipe, and the output end of the base air supply sub-pipe being connected to the base sealed air inlet of the coal mill; a primary air supply pipe, the output end of the primary air supply pipe being connected to the primary air inlet of the coal mill; a first detector, the two detection ends of the first detector being respectively connected to the main air supply pipe and the primary air supply pipe, the first detector being capable of detecting the differential pressure between the main air supply pipe and the primary air supply pipe; and a second detector, the two detection ends of the second detector being respectively connected to the base air supply sub-pipe and the primary air supply pipe, the second detector being capable of detecting the differential pressure between the base air supply sub-pipe and the primary air supply pipe.

[0006] Furthermore, the differential pressure detection system also includes a third detector, and the sealing air supply mechanism also includes a pull rod air supply sub-pipe. The output end of the pull rod air supply sub-pipe is connected to the pull pipe sealing air inlet of the coal mill. The two detection ends of the third detector are respectively connected to the pull rod air supply sub-pipe and the primary air supply pipe. The third detector can detect the differential pressure between the pull rod air supply sub-pipe and the primary air supply pipe.

[0007] Furthermore, the differential pressure detection system also includes a fourth detector, and the sealing air supply mechanism also includes a grinding roller air supply sub-pipe. The output end of the grinding roller air supply sub-pipe is connected to the grinding roller sealing air inlet of the coal mill. The two detection ends of the fourth detector are respectively connected to the grinding roller air supply sub-pipe and the primary air supply pipe. The fourth detector can detect the differential pressure between the grinding roller air supply sub-pipe and the primary air supply pipe.

[0008] Furthermore, the differential pressure detection system also includes a fifth detector, and the sealing air supply mechanism also includes a separator air supply sub-pipe. The output end of the separator air supply sub-pipe is connected to the separator sealing air inlet of the coal mill. A first monitoring point is provided at the upper end of the coal mill casing. One detection end of the fifth detector is connected to the separator air supply sub-pipe, and the other detection end of the fifth detector is located at the first monitoring point. The fifth detector can detect the differential pressure between the first monitoring point and the separator air supply sub-pipe.

[0009] Furthermore, the differential pressure detection system also includes a sixth detector. A second monitoring point is provided above the nozzle ring of the coal mill and at a first vertical distance from the nozzle ring of the coal mill. One detection end of the sixth detector is connected to the primary air supply pipe, and the other detection end of the sixth detector is located at the second monitoring point. The sixth detector is capable of detecting the differential pressure between the second monitoring point and the separator supply pipe.

[0010] Furthermore, the differential pressure detection system also includes a differential pressure switch, the two ends of which are connected to the main air supply pipe and the primary air supply pipe, respectively. The differential pressure switch is connected to the emergency stop circuit of the coal mill. The first detector, the second detector, the third detector, the fourth detector, and the fifth detector can all be connected to the emergency stop circuit through the differential pressure switch.

[0011] Furthermore, the differential pressure detection system also includes a distributed control system, which is connected to the first detector, the second detector, the third detector, the fourth detector, the fifth detector, and the sixth detector. The first detector, the second detector, the third detector, the fourth detector, the fifth detector, and the sixth detector are able to transmit the detected data to the distributed control system.

[0012] Furthermore, the number of differential pressure switches is not less than two.

[0013] Furthermore, the first detector, the second detector, the third detector, the fourth detector, the fifth detector, and the sixth detector are all differential pressure transmitters.

[0014] Analysis shows that this utility model discloses a coal mill differential pressure detection system. This utility model achieves additional monitoring of the coal mill by adding a differential pressure detector, thereby improving the comprehensiveness of monitoring the coal mill's sealing air and primary air. Attached Figure Description

[0015] The accompanying drawings, which form part of this application, are used to provide a further understanding of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an undue limitation of the present invention. Wherein:

[0016] Figure 1 A schematic diagram of the structure of an embodiment of this utility model.

[0017] Explanation of reference numerals in the attached diagram: 1. Main air supply pipe; 2. Primary air supply pipe; 3. Base air supply sub-pipe; 4. Tie rod air supply sub-pipe; 5. Grinding roller air supply sub-pipe; 6. Separator air supply sub-pipe; 7. First detector; 8. Second detector; 9. Third detector; 10. Fourth detector; 11. Fifth detector; 12. Sixth detector; 13. Coal mill. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. Various examples are provided by way of explanation of the present invention and not by way of limitation. In fact, those skilled in the art will recognize that modifications and variations can be made to the present invention without departing from the scope or spirit of the invention. For example, a feature shown or described as part of one embodiment may be used in another embodiment to produce yet another embodiment. Therefore, it is desirable that the present invention encompass such modifications and variations that fall within the scope of the appended claims and their equivalents.

[0019] In the description of this utility model, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and do not require that this utility model be constructed and operated in a specific orientation; therefore, they should not be construed as limitations on this utility model. The terms "connected," "linked," and "set up" used in this utility model should be interpreted broadly. For example, they can refer to a fixed connection or a detachable connection; a direct connection or an indirect connection through intermediate components; a wired connection, a radio connection, or a wireless communication signal connection. Those skilled in the art can understand the specific meaning of the above terms according to the specific circumstances.

[0020] The accompanying drawings illustrate one or more examples of the present invention. The detailed description uses numerals and letters to refer to features in the drawings. Similar or analogous reference numerals in the drawings and description have been used to refer to similar or analogous parts of the present invention. As used herein, the terms “first,” “second,” “third,” and “fourth,” etc., are used interchangeably to distinguish one component from another and are not intended to indicate the location or importance of a single component.

[0021] like Figure 1 As shown, according to an embodiment of the present invention, a coal mill differential pressure detection system is provided, comprising:

[0022] The sealed air supply mechanism includes a main air supply pipe 1 and a base air supply sub-pipe 3. The output end of the main air supply pipe 1 is connected to the input end of the pull rod air supply sub-pipe 4 and the input end of the base air supply sub-pipe 3. The output end of the base air supply sub-pipe 3 is connected to the base sealed air inlet of the coal mill 13. The main air supply pipe 1 uniformly distributes the air pressure. The base air supply sub-pipe 3 is directly connected to the base sealed air inlet of the coal mill 13, forming a positive air pressure barrier to prevent coal dust from overflowing into the transmission mechanism.

[0023] The primary air supply duct 2 is connected to the primary air inlet of the coal mill 13 at its output end. The primary air supply duct 2 serves as a coal powder conveying carrier, and its output end is connected to the primary air inlet of the coal mill 13 to maintain the dynamic balance of the gas-solid two-phase flow inside the coal mill 13.

[0024] The first detector 7 has two detection terminals connected to the main air supply pipe 1 and the primary air supply pipe 2, respectively. The first detector 7 bridges the main air supply pipe 1 and the primary air supply pipe 2 to monitor the pressure difference between the total pressure of the sealing air system and the reference pressure of the primary air. If the pressure of the main pipe is insufficient, it indicates that there is a leak in the entire sealing system or a fan failure.

[0025] The second detector 8 has two detection ends connected to the base air supply sub-pipe 3 and the primary air supply pipe 2, respectively. The second detector 8 bridges the base air supply sub-pipe 3 and the primary air supply pipe 2, and is specifically used to monitor the real-time pressure difference at the base sealing point. Because the base seal directly contacts the rotating components, its failure will cause pulverized coal to leak through the base seal. This detector can provide early warning of local seal failure.

[0026] Furthermore, the differential pressure detection system also includes a third detector 9, and the sealing air supply mechanism includes a pull rod air supply sub-pipe 4. The output end of the pull rod air supply sub-pipe 4 is connected to the pull rod sealing air inlet of the coal mill 13. The two detection ends of the third detector 9 are connected to the pull rod air supply sub-pipe 4 and the primary air supply pipe, respectively. The third detector 9 bridges the pull rod air supply sub-pipe 4 and the primary air supply pipe 2 to monitor the pressure difference between the two points in real time. The pull rod is prone to wear on the seals during its up-and-down reciprocating motion, and an abnormal decrease in pressure difference directly reflects the failure of the sealing ring or the leakage of pulverized coal. When the first detector 7 shows that the main pipe pressure is normal but the third detector 9 alarms, an independent fault in the pull rod sealing subsystem can be located, and targeted inspections of the coal mill and adjustments to the sealing air butterfly valve can be carried out in a timely manner to reduce the risk of pulverized coal leakage.

[0027] Furthermore, the differential pressure detection system also includes a fourth detector 10, and the sealing air supply mechanism includes a grinding roller air supply sub-pipe 5. The output end of the grinding roller air supply sub-pipe 5 is connected to the grinding roller sealing air inlet of the coal mill 13. The two detection ends of the fourth detector 10 are connected to the grinding roller air supply sub-pipe 5 and the primary air supply pipe 2, respectively. The fourth detector 10 bridges the grinding roller air supply sub-pipe 5 and the primary air supply pipe 2, and its differential pressure data reflects the integrity of the grinding roller seal. If the differential pressure drops sharply, it indicates that the grinding roller seal gap is severely leaking, and there is a risk of coal dust entering. Coal dust particles scour the grinding roller seal assembly, leading to lubricating oil contamination, grinding roller jamming, and oil leakage.

[0028] Furthermore, the differential pressure detection system also includes a fifth detector 11, and the sealing air supply mechanism includes a separator supply air sub-pipe 6. The output end of the separator supply air sub-pipe 6 is connected to the separator sealing air inlet of the coal mill 13. A first monitoring point is provided at the upper end of the coal mill 13 casing. One detection end of the fifth detector 11 is connected to the separator supply air sub-pipe 6, and the other detection end of the fifth detector 11 is located at the first monitoring point. One end of the fifth detector 11 is connected to the separator supply air sub-pipe 6, and the other end is placed at the first monitoring point. The fifth detector 11 directly measures the pressure difference between the separator sealing air and the airflow inside the coal mill 13, rather than using the primary air duct as a reference. The separator determines the fineness of the pulverized coal; its sealing failure will cause pulverized coal to enter the lubricating oil tank, leading to wear, jamming, and overall vibration of the transmission components inside the tank. The fifth detector 11 spans the sealing air sub-pipe and the internal space of the mill, more accurately reflecting the dynamic sealing performance of the separator in the coal mill 13, avoiding misjudgments caused by fluctuations in the primary airflow, and reducing the loss of sealing air.

[0029] Furthermore, the differential pressure detection system also includes a sixth detector 12, located above the nozzle ring of the coal mill 13, at a vertical distance of the first distance from the nozzle ring. One end of the sixth detector 12 is connected to the primary air supply pipe, and the other end of the fifth detector 11 is located at the second monitoring point. A second monitoring point is added in the critical area of ​​the nozzle ring, specifically located in the mill interior space above the nozzle ring. "Above" here typically refers to the position of the housing at a vertical distance of 100mm from the top of the nozzle ring, with a possible positional deviation of ±5mm. One end of the sixth detector 12 is connected to the primary air supply pipe 2, and the other end is placed at the second monitoring point to directly measure the pressure difference between the primary air and the nozzle ring area. The airflow velocity is highest at the nozzle ring, and the pressure difference determines the coal powder lifting capacity. If this value is too small, coarse particles fall, causing slag accumulation on the grinding disc; if it is too large, it increases the power consumption of the blower. The sixth detector 12 provides real-time resistance data of the primary air in the nozzle ring, guiding operators to more rationally adjust the air-coal ratio, become more familiar with the coal mill's operating status, and further analyze the necessity of nozzle ring replacement.

[0030] Preferably, the differential pressure detection system further includes a differential pressure switch, with its two ends connected to the main air supply pipe and the primary air supply pipe, respectively. The differential pressure switch is connected to the emergency stop circuit of the coal mill. The first detector 7, second detector 8, third detector 9, fourth detector 10, and fifth detector 11 can all be connected to the emergency stop circuit of the coal mill 13 via the differential pressure switch. Circuit connection and redundancy design need to be implemented according to the actual site conditions. The differential pressure switch acts as a relay device, connected to the signal output terminals of all detectors, and hardwired to the emergency stop circuit of the coal mill 13. When any detector reports a differential pressure lower than the safety threshold, the differential pressure switch triggers a stop command without requiring judgment from a distributed control system or programmable logic controller. The emergency stop circuit can be a trip relay of the coal mill 13, a PLC safety module, or a circuit breaker control circuit. Specifically, the normally open or normally closed contact of the differential pressure switch is connected in series in the control circuit of the trip relay. When the differential pressure exceeds the limit, the switch contacts actuate (close or open), energizing or de-energizing the trip relay coil. The trip relay contacts then disconnect the control circuit of the main motor circuit breaker of the coal mill, thus stopping the machine.

[0031] Furthermore, the differential pressure detection system also includes a distributed control system, which is connected to the first detector 7, the second detector 8, the third detector 9, the fourth detector 10, the fifth detector 11, and the sixth detector 12. The first detector 7, the second detector 8, the third detector 9, the fourth detector 10, the fifth detector 11, and the sixth detector 12 can transmit the detected data to the distributed control system. The distributed control system connects to each detector and collects differential pressure data in real time.

[0032] Furthermore, the number of differential pressure switches for the first detector is not less than two. In actual operation, in order to ensure the stability of operation, multiple differential pressure switches are usually set to ensure system redundancy.

[0033] Preferably, the first detector 7, the second detector 8, the third detector 9, the fourth detector 10, the fifth detector 11 and the sixth detector 12 are all differential pressure transmitters.

[0034] As can be seen from the above description, the embodiments of this utility model achieve the following technical effects: This utility model achieves additional monitoring of the coal mill by adding differential pressure detectors, improving the comprehensiveness of monitoring the coal mill's sealing air and primary air. Specifically, six sets of differential pressure detectors comprehensively monitor the coal mill, covering all high-risk sealing points. A differential pressure switch is directly connected to the emergency stop circuit; when the differential pressure at any sealing point falls below the safety threshold, a shutdown is triggered, preventing coal dust from entering the bearings / gearbox and causing equipment damage or explosion risks.

[0035] The above description is merely a preferred embodiment of this utility model and is not intended to limit the scope of this utility model. Various modifications and variations can be made to this utility model by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this utility model should be included within the protection scope of this utility model.

Claims

1. A coal mill differential pressure detection system, characterized in that, include: The sealing air supply mechanism includes a main air supply pipe and a base air supply sub-pipe. The output end of the main air supply pipe is connected to the input end of the base air supply sub-pipe, and the output end of the base air supply sub-pipe is connected to the base sealing air inlet of the coal mill. A primary air supply duct, the output end of which is connected to the primary air inlet of the coal mill; The first detector has two detection terminals connected to the main air supply pipe and the primary air supply pipe, respectively. The first detector is capable of detecting the pressure difference between the main air supply pipe and the primary air supply pipe. The second detector has two detection terminals connected to the base air supply sub-pipe and the primary air supply duct, respectively. The second detector can detect the pressure difference between the base air supply sub-pipe and the primary air supply duct.

2. The coal mill differential pressure detection system according to claim 1, characterized in that, The differential pressure detection system also includes a third detector, and the sealing air supply mechanism also includes a pull rod air supply sub-pipe. The output end of the pull rod air supply sub-pipe is connected to the pull pipe sealing air inlet of the coal mill. The two detection ends of the third detector are respectively connected to the pull rod air supply sub-pipe and the primary air supply pipe. The third detector can detect the differential pressure between the pull rod air supply sub-pipe and the primary air supply pipe.

3. The coal mill differential pressure detection system according to claim 2, characterized in that, The differential pressure detection system also includes a fourth detector, and the sealing air supply mechanism also includes a grinding roller air supply sub-pipe. The output end of the grinding roller air supply sub-pipe is connected to the grinding roller sealing air inlet of the coal mill. The two detection ends of the fourth detector are respectively connected to the grinding roller air supply sub-pipe and the primary air supply pipe. The fourth detector can detect the differential pressure between the grinding roller air supply sub-pipe and the primary air supply pipe.

4. The coal mill differential pressure detection system according to claim 3, characterized in that, The differential pressure detection system also includes a fifth detector, and the sealing air supply mechanism also includes a separator air supply sub-pipe. The output end of the separator air supply sub-pipe is connected to the separator sealing air inlet of the coal mill. A first monitoring point is provided at the upper end of the coal mill casing. One detection end of the fifth detector is connected to the separator air supply sub-pipe, and the other detection end of the fifth detector is located at the first monitoring point. The fifth detector can detect the differential pressure between the first monitoring point and the separator air supply sub-pipe.

5. The coal mill differential pressure detection system according to claim 4, characterized in that, The differential pressure detection system also includes a sixth detector. A second monitoring point is provided above the nozzle ring of the coal mill and at a first vertical distance from the nozzle ring of the coal mill. One detection end of the sixth detector is connected to the primary air supply pipe, and the other detection end of the sixth detector is located at the second monitoring point. The sixth detector can detect the differential pressure between the second monitoring point and the separator supply pipe.

6. The coal mill differential pressure detection system according to claim 5, characterized in that, The differential pressure detection system also includes a differential pressure switch, the two ends of which are connected to the main air supply pipe and the primary air supply pipe, respectively. The differential pressure switch is connected to the emergency stop circuit of the coal mill. The first detector, the second detector, the third detector, the fourth detector, and the fifth detector can all be connected to the emergency stop circuit through the differential pressure switch.

7. The coal mill differential pressure detection system according to claim 5, characterized in that, The differential pressure detection system also includes a distributed control system, which is connected to the first detector, the second detector, the third detector, the fourth detector, the fifth detector, and the sixth detector. The first detector, the second detector, the third detector, the fourth detector, the fifth detector, and the sixth detector are able to transmit the detected data to the distributed control system.

8. A coal mill differential pressure detection system according to claim 6, characterized in that, The number of differential pressure switches shall not be less than two.

9. A coal mill differential pressure detection system according to claim 5, characterized in that, The first detector, the second detector, the third detector, the fourth detector, the fifth detector, and the sixth detector are all differential pressure transmitters.

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