Dust content measuring device and dust content measuring method

Abstract

The invention provides a dust content measuring device which comprises a measuring branch pipe, a pre-charging device and an electrostatic measuring pipe, the pre-charging device and the electrostatic measuring pipe are arranged on the measuring branch pipe, and the initial end of the measuring branch pipe is connected to a gas conveying main pipe and can introduce gas to be measured from the gas conveying main pipe. The pre-charge device is located upstream of the electrostatic measurement tube. The invention further provides a dust content measuring method, the measuring method adopts the dust content measuring device for measurement, and the gas to be measured flowing through the electrostatic measuring tube is set as fixed pressure and fixed flow in the measuring process. The method has the beneficial effects that the gas to be measured is subjected to pre-charging treatment through the pre-charging equipment, and the charging property of dust in the gas to be measured is enhanced, so that the gas to be measured is suitable for dust content measurement through an electrostatic method.

Description

Technical Field

[0001] The invention relates to the technical field of pipeline gas transmission measurement, and in particular to a dust content measuring device and a dust content measuring method, which are suitable for measuring the dust content of high-pressure wet coal gas. Background Art

[0002] Coal gas is produced by gasifying raw coal under high temperature and high pressure. It is an important raw material for producing hydrogen, methanol, natural gas, fuel gas and other chemical products. The wet gas at the outlet of the gasifier usually contains a large amount of fine dust and needs to be processed through multiple processes such as quenching, cyclone, and washing to meet the downstream requirements for the dust content of wet gas to be less than 1mg / Nm 3 Although existing coal gasification technologies have restrictions on the dust content of wet coal gas outlet, in actual operation, with the fluctuation of coal quality, load changes, poor equipment status, adjustment of operating conditions and other factors, the dust content of wet coal gas may exceed the standard, which may lead to ash blockage at a node downstream, or even worse, affect the long-term stable operation of coal chemical equipment.

[0003] Therefore, during the gas transportation process, it is necessary to set up technical measures that can measure the dust content in the gas in real time, but the existing technology lacks more effective measurement means, especially for high-pressure wet gas, which has high pressure, high temperature, high saturated water vapor content and low dust content. Optional methods such as weighing method, capacitance method, piezoelectric crystal induction method, β-ray method, laser scattering method, oscillation balance method and electrostatic method cannot be successfully applied due to various limitations.

[0004] For example, a Chinese patent with publication number CN112284958A discloses a system and method for measuring the dust content of pipeline gas. It adopts the most basic weighing method and preliminarily solves the problem of whether there is a method for measuring the dust content of high-pressure wet gas. However, the patent has the following shortcomings: First, since the weight of the filter element itself is much larger than the amount of dust blocked for a considerable period of time, weighing and metering are difficult, resulting in low measurement accuracy; second, the measurement is the average amount over a period of time, which is not real-time, and all wet gas used for measurement during this period is wasted; third, the weighing measurement is performed manually, the operation is cumbersome, the degree of automation is low, and wet gas is toxic and flammable gas, which poses a safety risk.

[0005] For another example, the Chinese utility model patent with publication number CN204705569U discloses a dust concentration measuring device and the Chinese utility model patent with publication number CN207300814U discloses a plug-in dust concentration measuring instrument, which use the electrostatic method to measure the dust content, but both mainly improve the structure of the measuring device and are mainly used in low-pressure working conditions, and are still not suitable for high-pressure wet gas working conditions. It is expected that the electrostatic method will be used in the measurement of dust content in high-pressure wet gas, which faces many difficulties. These difficulties mainly include the relative lack of research on the charged properties of particles entrained in high-pressure wet gas from coal gasification, high pipeline gas pressure, low dust content, weak charge induction, high water vapor saturation humidity, and difficulty in ensuring accuracy.

[0006] Therefore, it is necessary to study a dust content measuring device and a measuring method suitable for high-pressure wet coal gas to solve the above problems or alleviate the impact of the above problems. Summary of the invention

[0007] The present invention provides a dust content measuring device and a dust content measuring method. A pre-charging device is used to pre-charge a gas to be measured, thereby enhancing the chargeability of dust in the gas to be measured, so that the gas to be measured is suitable for dust content measurement by an electrostatic method.

[0008] On one hand, the present invention provides a dust content measuring device, which includes a measuring branch pipe, a pre-charging device and an electrostatic measuring tube arranged on the measuring branch pipe, the initial end of the measuring branch pipe is connected to the gas transmission main pipe and can introduce the gas to be measured from the gas transmission main pipe, and the pre-charging device is located upstream of the electrostatic measuring tube. The pre-charging device can pre-charge the gas to be measured to increase the chargeability of the dust in the gas to be measured, and the electrostatic measuring tube uses an electrostatic method to measure the content of the dust in the gas to be measured after pre-charging.

[0009] In one embodiment, the electrostatic measurement tube has an electrostatic measurement probe therein, and the electrostatic measurement probe is a spiral structure wound around the axis of the electrostatic measurement tube and along a spiral path.

[0010] In one embodiment, a heating system is provided between the initial end of the measuring branch pipe and the pre-charging device, and the heating system is used to heat the measuring branch pipe.

[0011] In one embodiment, the pre-charge device is provided with a first smooth transition piece for connecting and transitioning with the measuring branch pipe, and / or the electrostatic measuring tube is provided with a second smooth transition piece for connecting and transitioning with the measuring branch pipe.

[0012] In one embodiment, a first pressure reducing valve is provided upstream of the electrostatic measuring tube, and a second pressure reducing valve is provided downstream of the electrostatic measuring tube, and the first pressure reducing valve and the second pressure reducing valve cooperate to adjust the pressure of the gas to be measured flowing through the electrostatic measuring tube.

[0013] In one embodiment, the electrostatic measuring tube is externally connected to a dust content display system, and the dust content display system can receive and process the electrostatic signal monitored by the electrostatic measuring tube and display the dust content data of the gas to be measured.

[0014] In one embodiment, the dust content display system has a temperature and humidity compensation function, and can correct the dust content data obtained from the electrostatic signal.

[0015] In one embodiment, a thermometer and a flow meter are provided on the measuring branch pipe between the pre-charging device and the electrostatic measuring tube.

[0016] In one embodiment, a safety valve is provided on the electrostatic measuring tube, and an outlet end of the safety valve is connected to a venting system downstream of the electrostatic measuring tube.

[0017] Another aspect of the present invention provides a dust content measurement method, which adopts the above-mentioned dust content measurement device for measurement, and during the measurement process, the gas to be measured flowing through the electrostatic measurement tube is set to a fixed pressure and a fixed flow rate.

[0018] Compared with the prior art, the dust content measuring device provided by the present invention has at least the following beneficial effects:

[0019] The dust content measuring device of the present invention is provided with a pre-charging device and an electrostatic measuring tube on the measuring branch pipe, and the pre-charging device is used to pre-charge the gas to be measured, so as to enhance the chargeability of the dust in the gas to be measured, and then the electrostatic measuring tube is used to measure the dust content in the pre-charged gas to be measured by an electrostatic method. In this way, the dust content measurement accuracy of the measuring device is high, the measurement time is short, and real-time response can be achieved. The degree of automation is high and the normal operation of the gas transmission main is not affected. In addition, the measuring device is particularly suitable for gases with low dust content and weak chargeability, such as high-pressure wet coal gas.

[0020] The dust content measuring method provided by the present invention also has the above-mentioned beneficial effects because it adopts the above-mentioned dust content measuring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Hereinafter, the present invention will be described in more detail based on embodiments and with reference to the accompanying drawings.

[0022] Figure 1 Schematic diagram of the structure of the dust content measuring device according to the embodiment of the present invention.

[0023] In the drawings, the same reference numerals are used for the same components. The drawings are not drawn to scale.

[0024] Reference numerals:

[0025] 1-measuring branch pipe, 2-pre-charging device, 3-electrostatic measuring tube, 4-electrostatic measuring probe, 5-heating system, 6-first smooth transition piece, 7-second smooth transition piece, 8-first pressure reducing valve, 9-second pressure reducing valve, 10-pressure gauge, 11-dust content display system, 12-thermometer, 13-flow meter, 14-safety valve, 15-valve, 16-gas transmission main pipe. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings.

[0027] Example 1

[0028] like Figure 1 As shown, the dust content measuring device of the present invention comprises a measuring branch pipe 1, a pre-charging device 2 and an electrostatic measuring tube 3 arranged on the measuring branch pipe 1, the initial end of the measuring branch pipe 1 is connected to the gas transmission main pipe 16 and can introduce the gas to be measured from the gas transmission main pipe 16, and the pre-charging device 2 is located upstream of the electrostatic measuring tube 3. The pre-charging device 2 can pre-charge the gas to be measured to increase the chargeability of the dust in the gas to be measured, and the electrostatic measuring tube 3 uses an electrostatic method to measure the dust content in the gas to be measured after pre-charging.

[0029] Specifically, the measuring branch pipe 1 is led out from the center of the gas transmission main pipe 16 to ensure that the gas to be measured introduced into the measuring branch pipe 1 is representative. After the gas to be measured flows into the measuring branch pipe 1, it flows through the pre-charging device 2 and the electrostatic measuring tube 3 respectively. The measuring device first pre-charges the gas to be measured through the pre-charging device 2 to enhance the chargeability of the dust in the gas to be measured, and then measures the dust content in the pre-charged gas to be measured by the electrostatic measuring tube 3 using the electrostatic method. In this way, the measuring device enhances the chargeability of the dust in the gas to be measured and improves the accuracy of the electrostatic measurement, thereby making the dust content measurement accurate and short in time, and the electrostatic method can achieve real-time response, with a high degree of automation and without affecting the normal operation of the gas transmission main pipe 16. The measuring device of the present invention is particularly suitable for gases with low dust content and weak charge, such as high-pressure wet coal gas.

[0030] It should be noted that the pre-charging device 2 can ionize the gas around the cathode by applying a relatively high DC voltage (generally 6-10KV) to the cathode, and the free ions collide with and combine with the dust particles in the gas to be measured to charge them. The cathode of the pre-charging device 2 can adopt a rare earth tungsten cathode, and the pre-charging device 2 can be grounded. The pre-charging device 2 can specifically solve the problem of weak dust charge in the gas to be measured.

[0031] It should also be explained that the explanation of the electrostatic method for measuring dust content is as follows: during the production and transportation process, the particles collide and rub with themselves, the pipe wall, and the gas, which makes the particles charged. When the charged particles pass near a specific metal probe, an electric charge will be generated on the probe and a weak current will be formed. There are two types of such charges. One is the friction electricity generated by the collision and friction between the particles and the probe. The method of using it alone to measure the dust content is called DC coupling. The other is the induced electricity generated when the charged particles first approach and then move away from the probe. The method of using it alone to measure the dust content is called AC coupling.

[0032] In one example, the electrostatic measurement tube 3 has an electrostatic measurement probe 4 therein, and the electrostatic measurement probe 4 is a spiral structure wound around the axis of the electrostatic measurement tube 3 and along a spiral path.

[0033] Specifically, the electrostatic measuring tube 3 is tubular, and the electrostatic measuring probe 4 improves the traditional rod-shaped (or needle-shaped) probe, and adopts a spiral structure distributed along the axial direction of the electrostatic measuring tube 3, so that the dust in the gas to be measured can fully generate charge induction with the electrostatic measuring probe 4, which is conducive to enhancing the electrostatic strength generated by the electrostatic measuring probe 4 to improve the measurement accuracy. The improvement of the electrostatic measuring probe 4 can specifically solve the problem of low dust content in the gas to be measured.

[0034] In one example, a heating system 5 is provided between the initial end of the measuring branch pipe 1 and the pre-charging device 2 , and the heating system 5 is used to heat the measuring branch pipe 1 .

[0035] Specifically, the heating system 5 is to heat the gas to be measured for a certain distance after it is introduced into the measuring branch pipe 1 and before it reaches the pre-charging device 2, so that its water vapor partial pressure is far away from the saturation state, and at the same time, the entrained droplets are evaporated to avoid entrained droplets in the gas to be measured, which affects the measurement accuracy of the dust content. The heating system 5 can be a strong heating section with a total length of not less than 5m set in the horizontal section of the measuring branch pipe 1, and the strong heating section can be heated by steam.

[0036] In one example, the pre-charging device 2 is provided with a first smooth transition piece 6 for connecting and transitioning with the measuring branch pipe 1 , and / or the electrostatic measuring tube 3 is provided with a second smooth transition piece 7 for connecting and transitioning with the measuring branch pipe 1 .

[0037] Specifically, if the inlet and / or outlet of the pre-charge device 2 is different from the diameter of the measuring branch pipe 1, a first smooth transition piece 6 needs to be provided at the connection between the two to avoid blocking dust particles at the connection and affecting the measurement result of the dust content. If the inlet and / or outlet of the electrostatic measuring tube 3 is different from the diameter of the measuring branch pipe 1, a second smooth transition piece 7 also needs to be provided at the connection between the two to avoid blocking dust particles at the connection and affecting the measurement result of the dust content.

[0038] Furthermore, the first smooth transition piece 6 and the second smooth transition piece 7 are both trumpet-shaped, with the end with a larger opening corresponding to a connection with a larger pipe diameter, and the end with a smaller opening corresponding to a connection with a smaller pipe diameter.

[0039] In one example, a first pressure reducing valve 8 is provided upstream of the electrostatic measuring tube 3 , and a second pressure reducing valve 9 is provided downstream of the electrostatic measuring tube 3 . The first pressure reducing valve 8 and the second pressure reducing valve 9 cooperate to adjust the pressure of the gas to be measured flowing through the electrostatic measuring tube 3 .

[0040] Specifically, the first pressure reducing valve 8 is arranged on the measuring branch pipe 1 between the pre-charge device 2 and the electrostatic measuring tube 3, and the second pressure reducing valve 9 is close to the outlet end of the electrostatic measuring tube 3. The first pressure reducing valve 8 and the second pressure reducing valve 9 can adjust the flow rate and pressure of the gas to be measured flowing through the electrostatic measuring tube 3 by adjusting their own openings. A pressure gauge 10 can also be provided on the measuring branch pipe 1 between the first pressure reducing valve 8 and the electrostatic measuring tube 3, and the pressure gauge 10 can be used to observe when the first pressure reducing valve 8 and the second pressure reducing valve 9 cooperate to adjust. Generally, the measured flow rate and measured pressure of the gas to be measured flowing through the electrostatic measuring tube 3 are adjusted to the calibration conditions, which can improve the measurement accuracy of the dust content.

[0041] In one example, the electrostatic measuring tube 3 is externally connected to a dust content display system 11 , and the dust content display system 11 can receive and process the electrostatic signal monitored by the electrostatic measuring tube 3 , and display the dust content data of the gas to be measured.

[0042] In one example, the dust content display system 11 has a temperature and humidity compensation function, and can correct the dust content data obtained from the electrostatic signal.

[0043] Specifically, temperature compensation is mainly used to compensate for the conversion of the measured gas from volume flow to standard volume flow, and humidity compensation is mainly used to compensate for the influence of humidity on the dust content measured by the electrostatic method. In this way, the dust content display system 11 uses the compensation function to make the measured dust content result more accurate and improve the dust content measurement accuracy. The required temperature in the dust content display system 11 can be monitored in real time by the thermometer 12, and the required humidity can be calculated by the temperature and pressure of the measured gas.

[0044] In one example, a thermometer 12 and a flowmeter 13 are provided on the measuring branch pipe 1 between the pre-charge device 2 and the electrostatic measuring tube 3. Thus, the temperature and flow rate of the gas to be measured in the measuring branch pipe 1 can be monitored by the thermometer 12 and the flowmeter 13. The thermometer 12 is also electrically connected to the dust content display system 11 to provide the monitored real-time temperature to the dust content display system 11.

[0045] In one example, a safety valve 14 is provided on the electrostatic measuring tube 3, and the outlet end of the safety valve 14 is connected to the venting system downstream of the electrostatic measuring tube 3. The measuring device provides a safety valve 14 on the electrostatic measuring tube 3, which can reduce the overall pressure level of the electrostatic measuring tube 3 and save investment.

[0046] It should be noted that the measuring device of the present invention is provided with valves 15 at the initial end of the measuring branch pipe 1 connected to the gas main pipe 16 and the tail end connected to the venting system. The valve 15 is used to control the activation or deactivation of the entire measuring device.

[0047] In order to better understand the above embodiment, the flow path of the gas to be measured in the measuring device is further described below with reference to the accompanying drawings.

[0048] The gas to be measured is drawn from the gas transmission main pipe 16 at a small flow rate into the measuring branch pipe 1. In the first section of the measuring branch pipe 1, it passes through the valve 15 at the initial end and the heating system 5, and then enters the pre-charge device 2 through the first smooth transition piece 6 to increase the charge of its dust. Then, in the second section of the measuring branch pipe 1, it passes through the thermometer 12, the flow meter 13, the first pressure reducing valve 8, and the pressure gauge 10, and then enters the electrostatic measuring tube 3 through the second smooth transition piece 7 for dust content measurement. The electrostatic measuring tube 3 is provided with an electrostatic measuring probe 4 with a spiral structure. When a part of the dust particles entrained by the gas to be measured collides and rubs with the probe, a weak direct current will be generated on the probe. At the same time, when another part of the dust particles pass near the probe, the probe will also generate a weak alternating current. The comprehensive direct current and alternating current signals are processed by the electrostatic signal processing and the dust content display system 11, and then compared with the built-in standard curve to obtain the dust content data. The measured gas is discharged into the venting system after passing through the second pressure reducing valve 9. At the same time, a safety valve 14 is arranged on the electrostatic measuring tube 3, and the gas passing through the safety valve 14 is simultaneously incorporated into the venting system.

[0049] Example 2

[0050] The dust content measurement method of the present invention adopts the dust content measurement device of the above-mentioned embodiment 1 for measurement, and during the measurement process, the gas to be measured flowing through the electrostatic measurement tube 3 is set to a fixed pressure and a fixed flow rate.

[0051] Dust content measurement methods include but are not limited to the following:

[0052] Step 1: Calibration under fixed measurement conditions. Select a fixed pressure P, a fixed flow rate F (which also fixes the flow rate of the gas and particles passing through the electrostatic measurement probe 4, and makes the flow rate within the optimal flow rate range of the electrostatic method measurement), and a fixed diameter D of the electrostatic measurement tube 3. For the same (or similar) gas atmosphere and the same entrained particles, the electrostatic method is used to calibrate the dust content measurement (wherein the technical solution for electrostatic method signal processing belongs to the prior art), and the fitting curve is embedded in the dust content display system 11. After signal processing, the electrical signal monitored by the electrostatic measurement probe 4 is first associated with the mass flow rate (unit: mg / s). Because the flow rate and pressure are fixed, and the temperature is monitored in real time, it can be converted into a dust concentration signal (unit: mg / Nm 3 ).

[0053] Step 2: Temperature and humidity correction and calibration. Temperature T mainly compensates for the conversion of gas from volume flow to standard volume flow. It does not require special calibration. It only needs to be monitored by the thermometer 12 and introduced into the built-in conversion formula of the dust content display system 11. According to the experimental results, humidity RH has a certain influence on the measurement of dust content by electrostatic method. The correction coefficient K is set. The deviation of humidity on dust content measurement is calibrated under the same conditions in step 1. The relative relationship curve of K~RH is obtained. It is also built into the dust content display system 11. The dust content measurement value is compensated by the following formula:

[0054] C=K·C'

[0055] Among them, C is the dust content output value, K is the humidity correction coefficient, and C' is the direct dust content measurement value. The measurement accuracy of the corrected dust content output value is controlled within 10%, which can meet the measurement accuracy requirements of the dust content of the gas to be measured, such as high-pressure wet coal gas.

[0056] In the dust content display system 11, the temperature T is monitored in real time by a thermometer 12 arranged on the measuring branch pipe 1; the humidity RH can be obtained by calculating the temperature and pressure of the saturated gas itself, and the temperature and pressure of the pipeline gas can be provided by the gasification device, which is regarded as one of the inherent parameters of the gas to be measured.

[0057] When the gas to be measured is high-pressure wet coal gas, the fixed pressure P can be a value between 1.5 and 2.5 MPag, the fixed flow rate F can be a value between 1 and 30 m / s, and the diameter D of the fixed electrostatic measuring tube 3 can be a value ≥ 0.1 m.

[0058] Step 3: On-site measurement. The actual measurement principle is consistent with the calibration conditions: using the same diameter D of the fixed electrostatic measuring tube 3, the two pressure reducing valves before and after the electrostatic measuring tube 3 are used to adjust the measurement conditions to be consistent with the calibration conditions (fixed pressure P and fixed flow F), and at the same time, the temperature and humidity signals are introduced into the dust content display system 11 for compensation, so that the dust content value can be accurately obtained.

[0059] The specific measurement steps of the dust content measurement method are as follows:

[0060] (1) In the initial state, all valves are in the closed position, all measuring instruments and heating are put into use, the electrostatic signal processing and dust content display system 11 is put into use, and the pre-charging device 2 is put into use.

[0061] (2) Open the valve 15 at the downstream end of the electrostatic measuring tube 3, open the second pressure reducing valve 9 to full open, and maintain the valve position to open the passage from the venting system to the flare.

[0062] (3) Open the valve 15 at the initial end of the measuring branch pipe 1, lead the gas to be measured to the front of the first pressure reducing valve 8, slowly open the first pressure reducing valve 8, and then adjust the fixed flow F and the fixed pressure P to the calibration condition through the cooperation of the first pressure reducing valve 8 and the second pressure reducing valve 9. At this time, the display value C of the dust content display system 11 is the dust content value of the measured gas to be measured. The C value already includes two compensations: temperature and humidity. The temperature compensation comes from the thermometer 12, and the humidity compensation comes from the calculated value RH given by the upstream device according to the temperature and pressure of the gas to be measured in the gas transmission main pipe 16.

[0063] Example 3

[0064] High-pressure wet coal gas refers specifically to the coal gas produced by coal gasification equipment (effective gas components are CO and H2, and others include CO2, N2, CH4 and water vapor, etc.) and similar gases. Its characteristics are high pressure (1.0-8.0MPag, which is related to the type of coal gasification technology), high temperature (150-250℃), saturated water vapor (saturated water vapor content is usually 30-60v%), low dust content (usually required to be less than 1mg / Nm 3 ).

[0065] In order to better understand the present invention, the following further describes how the dust content measuring device and method of the present invention solve the technical problem that the electrostatic method is not applicable to high-pressure wet coal gas.

[0066] (1) There is a lack of research on the charge properties of particles entrained in high-pressure wet coal gas from coal gasification: According to research, the properties of particles entrained in high-pressure wet coal gas from coal gasification are similar to those of dust in flue gas from power plants, and the latter is one of the conditions where the electrostatic method has been successfully used to measure dust content. On this basis, a charge induction test was conducted on dust particles entrained in high-pressure wet coal gas. The results showed that the dust particles were weakly charged, but could be measured by the electrostatic method after pre-charging. In addition, this process also accumulated sufficient data on charge properties, which can serve as a basis for application.

[0067] (2) High gas pressure and low dust content in pipeline: two problems solved together. The lowest concentration range of electrostatic measurement can reach 1mg / m 3 , even 0.1mg / m 3 However, in order to ensure accuracy, it is recommended to be no less than 10mg / m3 The dust content of high pressure wet gas is usually 1mg / Nm 3 Around, here Nm 3 The index is the volume at normal pressure and 0°C. The gas is compressed under high pressure, so the pressure factor must be considered. To ensure that the dust content of the gas is not less than 10mg / m 3 , the measurement pressure needs to be controlled to be no less than 1.5MPag. Combined with the applicable pressure range (≤2.5MPag) and pipe diameter range (≥0.1m) of the existing electrostatic measurement technology, the pipeline gas is led out to reduce the pressure at a certain flow rate, the pressure range is selected to be 1.5~2.5MPag, and the diameter of the measuring branch pipe 1 is not less than DN100 (0.1m).

[0068] (3) High gas temperature: The temperature of high-pressure wet coal gas is usually between 150 and 250°C. The coupling composition, pressure, water vapor content and other conditions limit the use of many dust content measurement methods. However, the use range of electrostatic measuring instruments is usually below 260°C. Even higher temperatures can be specially processed to meet the measurement requirements of this working condition.

[0069] (4) Weak charge induction: On the one hand, weak charge induction is related to the low dust content, and the solution has been mentioned in (2) above; on the other hand, it is related to the charged properties of the particles. In order to enhance the charge induction, a pre-charging device 2 is set up. By applying a relatively high DC voltage (6-10KV) to the cathode, the gas around the cathode (such as a rare earth tungsten cathode can be used), and the free ions collide with the dust particles in the airflow and combine to charge them. At the same time, the traditional plug-in rod probe is improved to a spiral electrostatic measurement probe 4.

[0070] (5) High water vapor saturation humidity: The influence of humidity on measurement is that liquid water is easily precipitated, which seriously affects the dust content measurement; secondly, experiments show that humidity itself will cause measurement deviation. For the former, before the exhaust gas enters the electrostatic measurement tube 3, steam strong heating is used for a certain distance to make the water vapor partial pressure away from the saturation state, and at the same time, the entrained droplets are evaporated; for the latter, according to the experimental data fitting, according to the humidity RH of the pipeline gas, the correction coefficient K is introduced to correct the measured dust content value.

[0071] (6) Measurement accuracy guarantee: In the case of flue gas dust content measurement, the pressure change is not large (close to normal pressure), and the accuracy requirement is not high (mainly used for high alarm). Therefore, although the accuracy of the electrostatic dust measuring instrument on the market is claimed to be 10%, it is actually for the calibration working condition before leaving the factory. In actual application, it is affected by many factors such as particle properties, gas flow rate, temperature, pressure (difference from the calibration particles), and the actual measurement value should have a larger deviation. For the dust content of high-pressure wet coal gas, the measurement accuracy is required to be strictly controlled within 10%, that is, the measurement working condition of the present invention is set to the measurement fixed condition calibration as in Example 2.

[0072] In summary, the present invention has the following advantages in measuring high-pressure wet coal gas compared with the prior art: high dust content measurement accuracy, short measurement time, real-time response, high degree of automation and no impact on the normal operation of the device, filling the gap in the measurement of dust content of high-pressure wet coal gas in coal gasification devices, and is of great significance to coal gasification devices and even carbon one chemical industry.

[0073] Although the present invention has been described with reference to preferred embodiments, various modifications may be made thereto and parts thereof may be replaced by equivalents without departing from the scope of the present invention. In particular, the various technical features mentioned in the various embodiments may be combined in any manner as long as there are no structural conflicts. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A dust content measuring device, characterized in that: The measuring device comprises a measuring branch pipe, a pre-charging device and an electrostatic measuring tube arranged on the measuring branch pipe, the initial end of the measuring branch pipe is connected to the gas transmission main pipe and can introduce the gas to be measured from the gas transmission main pipe, and the pre-charging device is located upstream of the electrostatic measuring tube; The pre-charging device can perform pre-charging processing on the gas to be measured to increase the chargeability of dust in the gas to be measured, and the electrostatic measuring tube uses an electrostatic method to measure the content of the dust in the gas to be measured after pre-charging.

2. The dust content measuring device according to claim 1, characterized in that: The electrostatic measuring tube has an electrostatic measuring probe in it. The electrostatic measuring probe is a spiral structure wound around the axis of the electrostatic measuring tube and along a spiral path.

3. The dust content measuring device according to claim 1, characterized in that: A heating system is provided between the initial end of the measuring branch pipe and the pre-charging device, and the heating system is used to heat the measuring branch pipe.

4. The dust content measuring device according to claim 1, characterized in that: The pre-charge device is provided with a first smooth transition piece for connecting and transitioning with the measuring branch pipe, and / or the electrostatic measuring tube is provided with a second smooth transition piece for connecting and transitioning with the measuring branch pipe.

5. The dust content measuring device according to claim 1, characterized in that: A first pressure reducing valve is provided upstream of the electrostatic measuring tube, and a second pressure reducing valve is provided downstream of the electrostatic measuring tube. The first pressure reducing valve cooperates with the second pressure reducing valve to adjust the pressure of the gas to be measured flowing through the electrostatic measuring tube.

6. The dust content measuring device according to claim 1, characterized in that: The electrostatic measuring tube is externally connected to a dust content display system, and the dust content display system can receive and process the electrostatic signal monitored by the electrostatic measuring tube and display the dust content data of the gas to be measured.

7. The dust content measuring device according to claim 6, characterized in that: The dust content display system has temperature and humidity compensation functions and can correct the dust content data obtained from the electrostatic signal.

8. The dust content measuring device according to claim 1, characterized in that: A thermometer and a flow meter are provided on the measuring branch pipe between the pre-charging device and the electrostatic measuring tube.

9. The dust content measuring device according to claim 1, characterized in that: The electrostatic measuring tube is provided with a safety valve, and the outlet end of the safety valve is connected and incorporated into the venting system downstream of the electrostatic measuring tube.

10. A method for measuring dust content, characterized in that: The measuring method adopts the dust content measuring device as described in any one of claims 1 to 9 for measurement, and during the measurement process, the gas to be measured flowing through the electrostatic measuring tube is set to a fixed pressure and a fixed flow rate.

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