Air volume measuring device based on differential pressure multistage amplification and active anti-blocking

Abstract

The utility model discloses an air volume measuring device based on differential pressure multistage amplification and active anti-blocking. A traditional differential pressure type measuring device is weak in differential pressure signal and only depends on the difference value of total pressure and static pressure, the differential pressure value is lower than 50 Pa under the low-flow-speed working condition, consequently, the measuring precision is low, a protection mechanism is difficult to trigger, the anti-blocking effect of a gravity settling method is limited, and a pressure tapping hole is prone to being blocked under a vertical pipeline or large-particle dust scene. The device comprises a positive pressure side sampling device and a negative pressure side sampling device, the positive pressure side sampling device comprises a positive pressure sampling barrel, and a plurality of sampling nozzles are fixed on the positive pressure sampling barrel; the sampling nozzle comprises an air inlet nozzle and a pressure stabilizing pipe, the pressure stabilizing pipe is communicated with the side surface of the air inlet nozzle, and a separation plate and a vortex separation area are arranged in the air inlet nozzle; the sampling barrel comprises an inner culvert pipe and an outer culvert pipe, the inner culvert pipe is located in the outer culvert pipe, and a pressure taking pipe penetrates through the outer culvert pipe to be communicated with the inner culvert pipe. The device is used for air volume measurement.

Description

Technical Field

[0001] This utility model relates to an air volume measurement device based on differential pressure multi-stage amplification and active anti-blocking. Background Technology

[0002] Traditional differential pressure measuring devices (such as flute-type and bar-type flow meters) have the following drawbacks:

[0003] 1. Weak differential pressure signal: It only relies on the difference between total pressure and static pressure. Under low flow rate conditions, the differential pressure value is less than 50Pa, resulting in low measurement accuracy and difficulty in triggering the protection mechanism.

[0004] 2. Prone to clogging: Gravity settling method has limited anti-clogging effect, and pressure taps are prone to clogging in vertical pipes or large dust particles.

[0005] 3. High pressure loss: The structural design leads to significant fluid energy loss, affecting system energy efficiency.

[0006] To address the aforementioned problems, this invention proposes an integrated solution for differential pressure multi-stage amplification and active anti-blocking. Utility Model Content

[0007] The present invention aims to solve the aforementioned technical problems by providing an air volume measurement device based on differential pressure multi-stage amplification and active anti-blocking.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] An air volume measurement device based on differential pressure multi-stage amplification and active anti-blocking comprises a positive pressure side sampling device and a negative pressure side sampling device. The positive pressure side sampling device and the negative pressure side sampling device are respectively connected to a dust settling device through pipelines. The air outlet of the dust settling device is connected to a differential pressure transmitter through a pipeline. The positive pressure side sampling device includes a positive pressure sampling cylinder, and multiple sampling nozzles are fixed on the positive pressure sampling cylinder.

[0010] The sampling nozzle includes an air inlet and a pressure stabilizing tube. The pressure stabilizing tube is connected to the side of the air inlet. The air inlet has a separation plate and a vortex separation zone inside.

[0011] The sampling container includes an inner tube and an outer tube, with the inner tube located inside the outer tube, and the pressure tapping tube passing through the outer tube and communicating with the inner tube.

[0012] The air volume measurement device based on differential pressure multi-stage amplification and active anti-blocking is characterized in that: the outer duct is a variable diameter duct with an ejector contraction section in its middle.

[0013] The air volume measurement device based on differential pressure multi-stage amplification and active anti-blocking is characterized in that: the inner tube is a cylindrical tube with a contraction section in the middle. Beneficial effects

[0014] 1. The sampling nozzle of this utility model adopts a separation plate and vortex separation zone design. The dust is thrown out to the ash discharge channel due to centrifugal force, avoiding entering the pressure tapping chamber.

[0015] 2. The outer bypass section of this invention guides and rectifies the airflow, making it more uniform and stable before entering the inner bypass section, thus improving measurement accuracy. The inner bypass section, through its gradually narrowing and widening channel design, allows the airflow to accelerate and decelerate smoothly, enabling the calculation of air volume based on pressure differences. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of this utility model;

[0017] Figure 2 This is the front view of the sampling nozzle;

[0018] Figure 3 This is a top view of the sampling nozzle;

[0019] Figure 4 This is a schematic diagram of the internal structure of the sampling nozzle;

[0020] Figure 5 This is a schematic diagram of the sampling container;

[0021] Figure 6 This is a schematic diagram of the internal structure of the sampling tube;

[0022] In the diagram: 1. Positive pressure side sampling device; 2. Negative pressure side sampling device; 3. Dust settling device; 4. Differential pressure transmitter; 5. Temperature transmitter; 6. Sampling nozzle; 7. Sampling bucket; 8. Pressure transmitter; 9. Positive pressure sampling cylinder; 61. Air inlet cavity; 62. Dust baffle rib; 63. Pressure stabilizing pipe; 64. Separation plate; 65. Eddy current separation zone; 71. Inner tube; 72. Outer tube; 73. Ejector section; 74. Pressure tapping pipe; 75. Contraction section. Detailed Implementation

[0023] Reference Figure 1 A wind volume measurement device based on differential pressure multi-stage amplification and active anti-blocking comprises a positive pressure side sampling device 1 and a negative pressure side sampling device 2. The positive pressure side sampling device and the negative pressure side sampling device are respectively connected to a dust settling device 3 through pipelines. The air outlet of the dust settling device is connected to a differential pressure transmitter 4 through a pipeline. The positive pressure side sampling device includes a positive pressure sampling cylinder 9, and multiple sampling nozzles 6 are fixed on the positive pressure sampling cylinder.

[0024] The sampling nozzle includes an air inlet and a pressure stabilizing tube 63. The pressure stabilizing tube is connected to the side of the air inlet. The air inlet has a separation plate 64 and a vortex separation zone 65 inside. The air inlet has an air inlet cavity 61 and a dust-blocking rib 62 at the flue gas outlet end of the air inlet.

[0025] After the measuring medium flows to the sampling nozzle, it hits the separation plate and the dust is separated in the eddy current separation zone, thereby preventing dust from entering the positive pressure sampling cylinder 9 of the positive pressure side measuring device;

[0026] The sampling bucket includes an inner tube 71 and an outer tube 72. The inner tube is located inside the outer tube, and the pressure tapping tube 74 passes through the outer tube and communicates with the inner tube.

[0027] The outer duct is a variable diameter tube with an ejector contraction section in its middle, and the inner duct is a cylindrical tube with a contraction section 75 in its middle.

[0028] When flue gas flows through the sampling barrel, both the outer and inner pipes have flue gas flowing through them. The flue gas velocity in the outer pipe is v1, and the flue gas velocity in the inner pipe is v2. Because the outer pipe is a variable diameter pipe with an ejector contraction section, v1 is accelerated and is higher than v2. In this case, after the flue gas flows through, v1 is higher than v2 at the outlet, which has an ejector effect. Under the action of v1, the flow velocity of v2 can be increased. After the velocity of v2 increases, the internal pressure will decrease. Therefore, the pressure taken on the negative pressure side will decrease, and the positive pressure-negative pressure difference will increase, realizing differential pressure amplification.

[0029] The pressure from the positive pressure side sampling device and the negative pressure side sampling device is fed into the positive pressure side and the negative pressure side of the differential pressure transmitter, respectively. The transmitter sends the differential pressure signal to the DCS. The temperature transmitter measures the air temperature and uploads the signal to the DCS for air volume compensation.

[0030] Furthermore, the mass flow rate is calculated according to the following formula:

[0031] Qm=K*SQRT

dP*(Ph+Pg) / (273.15+t)

[0032] Where K is the instrument coefficient;

[0033] dP is the differential pressure signal sent to the DCS by the differential pressure transmitter (4);

[0034] Ph represents the local average atmospheric pressure.

[0035] Pg is the actual wind pressure measured by the pressure transmitter (8) and sent to the DCS;

[0036] t is the temperature signal sent to the DCS by the temperature transmitter (5).

Claims

1. An airflow measurement device based on differential pressure multi-stage amplification and active anti-clogging, comprising a positive pressure side sampling device and a negative pressure side sampling device, wherein the positive pressure side sampling device and the negative pressure side sampling device are respectively connected to a dust settling device through pipelines, and the outlet of the dust settling device is connected to a differential pressure transmitter through a pipeline, characterized in that: The positive pressure sampling device includes a positive pressure sampling cylinder, on which multiple sampling nozzles are fixed. The sampling nozzle includes an air inlet and a pressure stabilizing tube. The pressure stabilizing tube is connected to the side of the air inlet. The air inlet has a separation plate and a vortex separation zone inside. The sampling container includes an inner tube and an outer tube, with the inner tube located inside the outer tube, and a pressure tapping tube passing through the outer tube and communicating with the inner tube.

2. The airflow measurement device based on differential pressure multi-stage amplification and active anti-clogging as described in claim 1, characterized in that: The outer duct is a variable diameter duct with an ejector contraction section in its middle.

3. The air flow measuring device based on differential pressure multi-stage amplification and active anti-blocking according to claim 2, characterized in that: The inner tube is a cylindrical tube with a contraction section in the middle.

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