CN209148055U - A temperature-controlled heat tracing pitot tube - Google Patents

Abstract

A kind of temperature control heat tracing Pitot tube, belongs to flue gas inspection equipment technical field.Heating film and insulating layer are successively enclosed with outside the total pressure test tube and back pressure test tube of the temperature control heat tracing Pitot tube respectively, thermal insulation layer is enclosed with outside the insulating layer of total pressure test tube and back pressure test tube jointly, the outside of thermal insulation layer is equipped with protection outer housing, the side wall that at least one temp probe passes through protection outer housing protrudes into thermal insulation layer, the measurement end of temp probe is close to the position that the insulating layer of total pressure test tube and back pressure test tube contacts with each other, the one end of total pressure connector far from total pressure test tube, the one end of one end and temp probe far from its measurement end of back pressure connector far from back pressure test tube is connect with online monitoring instruments.The temperature control heat tracing Pitot tube, temperature in Pitot tube can be maintained 80 DEG C or more, solve Pitot tube etching problem caused by due to condensation, online monitoring instruments have the function of purging, the solid particulate matter impurity in discharge gas can be effectively removed, the blockage problem of Pitot tube is efficiently solved.

Description

A temperature-controlled heat tracing pitot tube

technical field

The utility model relates to the technical field of smoke detection equipment, in particular to a temperature-controlled heat tracing pitot tube.

Background technique

In the smoke detection work, the pitot tube is one of the most commonly used sampling devices in the detection and sampling equipment. When measuring, insert the probe of the Pitot tube flowmeter into the pipeline, and make the central axis of the total pressure and back pressure probe in the center of the flow section and in the same direction as the streamline. And transmit it to the monitoring system; at the same time, the back pressure probe measuring hole picks up the throttling static pressure and also transmits it to the monitoring system, the monitoring system reads the total and static pressure values, finds the difference between the dynamic pressure and the static pressure, and uses the formula to calculate Outflow velocity value.

However, since the flue gas contains various gas components, such as water vapor, sulfur dioxide, nitrogen oxides, etc., it will not only corrode the pitot tube, but also cause the pitot tube to be blocked due to the condensation of the gas when the temperature is low, which will affect the accuracy of detection. sex. Therefore, the corrosion and blockage of pitot tubes are two major problems to be solved urgently in flow velocity measurement. At present, the common pitot tubes used for flow velocity measurement are generally made of stainless steel and stainless steel sheaths for full pressure and back pressure pipes to solve the problem of corrosion and wear, but there is no better solution to the problem of clogging.

SUMMARY OF THE INVENTION

In order to solve the problems existing in the prior art, the purpose of this utility model is to provide a temperature-controlled heat tracing pitot tube, which can maintain the temperature in the pitot tube above 80°C, and solves the problem of pitot tube corrosion caused by condensation, The online monitoring instrument has a purging function, which can effectively remove the solid particulate impurities in the exhaust gas, and effectively solve the clogging problem of the pitot tube.

In order to achieve the above object, the technical scheme of the present utility model is:

A temperature-controlled heat tracing pitot tube includes a full-pressure measuring tube and a back-pressure measuring tube, one end of the full-pressure measuring tube is connected to a full-pressure joint, and the other end of the full-pressure measuring tube is provided with a full-pressure measuring hole, and the One end of the back pressure measuring tube is connected with the back pressure joint, and the other end of the back pressure measuring tube is provided with a back pressure measuring hole. The insulating layers of the measuring tube and the back pressure measuring tube are jointly wrapped with a heat insulating layer, the outside of the heat insulating layer is provided with a protective outer casing, and at least one temperature probe protrudes into the insulating layer through the side wall of the protective outer casing, The measuring end of the temperature probe is close to the part where the insulation layers of the full pressure measuring tube and the back pressure measuring tube are in contact with each other. One end of the measuring end is connected with the online monitoring instrument.

The outside of the online monitoring instrument is provided with a temperature display, a pressure display, a full pressure interface, a back pressure interface, a temperature probe interface and a purge air source interface, and the inside of the online monitoring instrument is provided with a differential pressure transmitter. transmitter 2, timer 1, timer 2, timer 3, timer 4, solenoid valve 1, solenoid valve 2, solenoid valve 3 and solenoid valve 4, the end of the temperature probe away from its measuring end is connected to the temperature probe interface , the temperature probe interface is connected to the temperature display, the end of the full-pressure connector away from the full-pressure measuring tube is connected to the full-pressure interface, and the full-pressure interface is connected to the input end of the differential pressure transmitter one through pipeline three. A solenoid valve 3 and a timer 3 are provided. One end of the back pressure connector away from the back pressure measuring tube is connected to the back pressure interface, and the back pressure interface is connected to the input end of the differential pressure transmitter 2 through pipeline 4. The pipeline 4 There are four solenoid valves and four timers on it, the output end of the differential pressure transmitter 1 and the output end of the differential pressure transmitter 2 are both connected to the pressure display, and one end of the purge air source interface is connected to the external air source , the other end of the purging air source interface is connected with pipeline 3 through pipeline 1, and communicated with pipeline 4 through pipeline 2. Said pipeline 1 is provided with solenoid valve 1 and timer 1, and pipeline 2 is provided with solenoid valve 2 and Timer two.

The solenoid valve 3 and the timer 3 are both located between the connection between the pipeline 1 and the pipeline 3 and the differential pressure transmitter 1, and the solenoid valve 4 and the timer 4 are both located at the connection between the pipeline 2 and the pipeline 4 and the pressure difference. difference between transmitter two.

The heating film is a polyimide film PI electric heating film.

The insulating layer is silicon rubber, asbestos or mica board.

The heat insulating layer is glass fiber wool felt, polyurethane foam material or rock wool.

The beneficial effects of the present utility model:

(1) The temperature-controlled heat tracing pitot tube uses a heating film to heat the full pressure measuring tube and the back pressure measuring tube to ensure that the flue gas will not be in a condensed state, and prevent the corrosion and blockage of the full pressure measuring tube and the back pressure measuring tube. Make flow measurement more accurate;

(2) The temperature probe is located near the contact between the insulating layers of the full pressure measuring tube and the back pressure measuring tube, and can monitor the temperature of the full pressure measuring tube and the back pressure measuring tube at the same time, so as to control the heating switch of the heating film according to the set temperature, If the temperature is too high, the heating of the heating film will be stopped, and if the temperature is low, the heating switch of the heating film will be turned on. In addition, as a special medium, the flue gas has a temperature range of about 40-120 °C. In special cases, it may reach a higher temperature. In order to To prevent the flue gas from condensing in a low temperature state, the utility model can maintain the temperature in the pitot tube above 80°C, and solve the problem of pitot tube corrosion caused by condensation;

(3) The online monitoring instrument can detect the dynamic pressure, static pressure and temperature in the pipeline, and can perform real-time temperature monitoring to make the flow rate measurement more accurate;

(4) The online monitoring instrument has a purging function, which can effectively remove impurities such as solid particles contained in the exhaust gas, further ensure that the pitot tube is not blocked, and can effectively solve the problem of blocking the pitot tube, increase the stability of the measurement, and reduce the operation and maintenance. maintenance of personnel;

(5) The temperature-controlled heat tracing pitot tube of the present invention can be widely used in various environmental protection and clean rooms, mine ventilation and energy management departments, and can be used to control the gas flow rate of various boilers, furnace flues and mine exhaust pipes. , temperature and pressure are monitored online.

Description of drawings

Fig. 1 is the structural representation of a kind of temperature control heat tracing pitot tube provided by the utility model;

Fig. 2 is the enlarged view of B in Fig. 1 provided by the utility model;

Fig. 3 is the A-A sectional view in Fig. 1 provided by the present utility model;

Fig. 4 is the installation schematic diagram of a kind of temperature control heat tracing pitot tube provided by the utility model;

FIG. 5 is a schematic structural diagram of an on-line monitoring instrument provided by the present invention.

in,

1. Full pressure joint; 2. Back pressure joint; 3. Full pressure measuring tube; 4. Back pressure measuring tube; 5. Temperature probe; 6. Protective shell; 7. Full pressure measuring hole; 8. Back pressure measuring hole ;9, flue gas flow direction; 10, heating film; 11, insulating layer; 12, heat insulation layer; 14, full pressure interface; 15, back pressure interface; 16, purge air source interface; 17, temperature display; 18- 1. Differential pressure transmitter one; 18-2, differential pressure transmitter two; 19-1, timer one; 19-2, timer two; 19-3, timer three; 19-4, timer Four; 20, solenoid valve one; 21, solenoid valve two; 22, solenoid valve three; 23, solenoid valve four; 24, pressure display; 25, temperature probe interface.

Detailed ways

The technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. In the description of the present utility model, it should be noted that, unless otherwise expressly specified and limited, the terms "installed", "provided with", "connected", etc., should be understood in a broad sense, for example, "connected" may be a fixed The connection can also be a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal communication between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood in specific situations. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "one end", "the other end", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and the The description is simplified rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention. Furthermore, the terms "one," "two," "three," and "four" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

In order to solve the problems existing in the prior art, as shown in FIG. 1 to FIG. 5 , the present invention provides a temperature-controlled heat tracing pitot tube, which includes a full-pressure measuring tube 3 and a back-pressure measuring tube 4. The full-pressure measuring tube 3 One end is connected with the full pressure joint 1, the other end of the full pressure measuring tube 3 is provided with a full pressure measuring hole 7, one end of the back pressure measuring tube 4 is connected with the back pressure joint 2, and the other end of the back pressure measuring tube 4 is provided with a back pressure measuring hole 7. The pressure measuring hole 8, the full pressure measuring tube 3 and the back pressure measuring tube 4 are respectively wrapped with a heating film 10 and an insulating layer 11, and the insulating layer 11 of the full pressure measuring tube 3 and the back pressure measuring tube 4 is jointly wrapped with a heat insulation layer. Layer 12, a protective outer casing 6 is provided outside the thermal insulation layer 12, and at least one temperature probe 5 protrudes into the thermal insulation layer 12 through the side wall of the protective outer casing 6. In this embodiment, a temperature probe 5 is used, and the temperature The measuring end of the probe 5 is close to the part where the insulating layer 11 of the full pressure measuring tube 3 and the insulating layer 11 of the back pressure measuring tube 4 are in contact with each other. One end of the measuring tube 4 and one end of the temperature probe 5 away from its measuring end are both connected to the online monitoring instrument.

The outside of the online monitoring instrument is provided with a temperature display 17, a pressure display 24, a full pressure interface 14, a back pressure interface 15, a temperature probe interface 25 and a purge air source interface 16, and a differential pressure transmitter is installed inside the online monitoring instrument. 18-1, differential pressure transmitter two 18-2, timer one 19-1, timer two 19-2, timer three 19-3, timer four 19-4, solenoid valve one 20, solenoid valve two 21. Solenoid valve 3 22 and solenoid valve 4 23, the end of the temperature probe 5 away from its measuring end is connected with the temperature probe interface 25, the temperature probe interface 25 is connected with the temperature display 17, the end of the full pressure joint 1 away from the full pressure measuring tube 3 is connected with The full pressure interface 14 is connected, and the full pressure interface 14 is connected with the input end of the differential pressure transmitter 1 18-1 through the pipeline 3. The pipeline 3 is provided with a solenoid valve 3 22 and a timer 3 19-3, and the back pressure connector 2 is far away One end of the back pressure measuring tube 4 is connected with the back pressure interface 15, and the back pressure interface 15 is connected with the input end of the differential pressure transmitter two 18-2 through the pipeline four, and the pipeline four is provided with a solenoid valve four 23 and a timer four 19 -4, the output end of the differential pressure transmitter 18-1 and the output end of the differential pressure transmitter 2 18-2 are connected to the pressure display 24, and one end of the purge air source interface 16 is connected to the external air source, and the The other end of the purging air source interface 16 is communicated with the pipeline 3 through the first pipeline, and at the same time the other end of the purging air source interface 16 is also communicated with the pipeline 4 through the pipeline 2. The pipeline 1 is provided with a solenoid valve 1 20 and a timer 19. -1, there are solenoid valve two 21 and timer two 19-2 on pipeline two. Solenoid valve three 22 and timer three 19-3 are located between the connection between pipeline one and pipeline three and differential pressure transmitter one 18-1, solenoid valve four 23 and timer four 19-4 are located between pipeline two and pipeline four between the connection and the differential pressure transmitter II 18-2.

The heating film 10 is a polyimide film PI electric heating film. The insulating layer 11 is made of silicon rubber, asbestos or mica board. In this embodiment, the mica board is a soft mica board. The insulating layer 12 is glass fiber wool felt, polyurethane foam material or rock wool.

In this embodiment, the online monitoring instrument has three functions of temperature monitoring, pressure monitoring and purging, and can monitor the temperature of the temperature-controlled heat tracing pitot tube, the pressure of the full pressure measuring hole 7 and the back pressure measuring hole 8 in real time, and can monitor the temperature of the temperature-controlled heat tracing pitot tube in real time. Remove solid particles from full pressure measuring tube 3 and back pressure measuring tube 4. The external air source is compressed air. The purging frequency of the full-pressure measuring tube 3 is controlled by the solenoid valve 1 20 and the timer 1 19-1, and the purging back pressure is controlled by the solenoid valve 2 21 and the timer 2 19-2. Measuring tube 4 purge frequency. In this embodiment, the model of temperature display 17 is SUHED's HD-730, the model of differential pressure transmitter 1 18-1 and the model of differential pressure transmitter 2 18-2 are MIK-6000 of Sopromet, and the model of pressure display For Ouwei's XMT, the temperature probe 5 model is MF-53-103-F-3950 produced by Xingxiang, timer one 19-1, timer two 19-2, timer three 19-3 and timer four 19 The models of -4 are H7ET-BLM of SANTEN.

In this utility model, choosing the correct installation position is the premise for the reliable and effective operation of the temperature-controlled heat-tracing pitot tube, and the installation quality of the temperature-control heat-tracing pitot tube has a great influence on its measurement accuracy. Therefore, when selecting the measurement point, it should be away from the parts that are prone to flow fluctuations, such as fans, valves, elbows, etc., and there should be a 3D ~ 5D straight pipe section upstream of the measurement point to ensure the measurement point. The velocity distribution law of the overcurrent section meets the requirements. In addition, the following points should be paid attention to: ①The installation position should avoid flue bends and the parts where the section changes sharply; ②The installation position should avoid the position of corrosion and harmful gas; ③The installation point should be easy to reach, which is helpful for installation and maintenance. Maintain the safety of the channel; ④The arrangement of the signal lines should be kept away from other electromagnetic devices to avoid mutual interference.

The working principle of the above-mentioned temperature-controlled heat tracing pitot tube is as follows:

As shown in Figure 4, when measuring, insert the temperature-controlled heat tracing pitot tube into the pipeline, and make the central axis of the full pressure measuring hole 7 and the back pressure measuring hole 8 at the center of the flow section and consistent with the flue gas flow direction 9. The pressure measuring hole 7 faces the incoming flow and detects the full pressure of the fluid. It is connected to the full pressure interface 14 of the online monitoring instrument through the full pressure joint 1, and the full pressure is transmitted to the differential pressure transmitter 1 18-1, and the differential pressure is transmitted. The total pressure value measured by device 1 18-1 is displayed on the pressure display 24; at the same time, the back pressure measuring hole 8 faces the incoming flow, picks up the throttling static pressure, and connects with the back pressure interface 15 of the online monitoring instrument through the back pressure connector 2 , the static pressure is transmitted to the differential pressure transmitter two 18-2, and the static pressure value measured by the differential pressure transmitter two 18-2 is displayed on the pressure display 24. In actual work, the dynamic pressure value is obtained according to the total pressure value and the static pressure value. The dynamic pressure value is the difference between the total pressure value and the static pressure value. The dynamic pressure value is related to the flow rate of the flue gas. The larger the flow rate, the larger the dynamic pressure value. When there is no flow rate, the dynamic pressure value is zero, so according to Bernoulli equation, the flow rate value is calculated from the dynamic pressure, flue gas gas constant, flue gas temperature, Pitot tube correction coefficient, etc.

As shown in Figure 5, the solid line is the pipeline connection to represent the gas path, and the dashed line is the wire connection to represent the line. In addition to measuring the total pressure and static pressure of the flue gas, the online monitoring instrument can also measure the temperature of the contact part of the insulation layer 11 of the total pressure measuring tube 3 and the back pressure measuring tube 4. The temperature probe 5 picks up the temperature value and displays it on the temperature display. 17 shows that the operator controls the switch of the heating film 10 according to the temperature displayed on the temperature display 17 and the set temperature. In this embodiment, the temperature displayed by the display is higher than or equal to 80°C, and the heating switch of the heating film 10 is turned off. , the temperature displayed by the display is lower than 80°C, and the heating switch of the heating film 10 is turned on to prevent the flue gas from condensing in a low temperature state, so as to solve the technical problem of pitot tube corrosion caused by condensation. In addition, in the process of measurement, it is necessary to carry out purging irregularly to clean the temperature-controlled heat tracing pitot tube.

There are two working modes of the online monitoring instrument of the utility model:

The first working mode: the temperature-controlled heat tracing pitot tube is in the working state, open the solenoid valve 3 22 and solenoid valve 4 23, close the solenoid valve 1 20 and solenoid valve 2 21, and the flue gas passes through the full pressure measuring hole 7 and the full pressure in turn. Measuring tube 3, full pressure connector 1, full pressure interface 14, solenoid valve 3 22 and differential pressure transmitter 1 18-1, the full pressure value is displayed on the pressure display 24, and the flue gas passes through the back pressure measuring holes 8, The back pressure measuring tube 4, the back pressure connector 2, the back pressure interface 15, the solenoid valve 4 23 and the differential pressure transmitter 2 18-2, display the static pressure value on the pressure display 24;

The second working mode: when cleaning the temperature-controlled heat tracing pitot tube, the third solenoid valve and the fourth solenoid valve 23 are electrically closed, the first solenoid valve 20 and the second solenoid valve 21 are opened, and the compressed air passes through the purging air source interface 16. The compressed air passes through the solenoid valve 1 20, the full pressure interface 14, and the full pressure joint 1 in sequence to clean the full pressure measuring tube 3. At the same time, another part of the compressed air passes through the solenoid valve 2 21, the back pressure interface 15, and the back pressure joint 2 in turn. , to clean the back pressure measuring tube 4.

When the online monitoring instrument is working, the timer 1 19-1 is used to control the opening and closing of the solenoid valve 1 20 to control the purging frequency of the full pressure measuring tube 3, and the timer 2 19-2 is used to control the opening and closing of the solenoid valve 2 21. In order to control the purging frequency of the back pressure measuring tube 4, in this embodiment, the purging frequencies of the full pressure measuring tube 3 and the back pressure measuring tube 4 are the same, and the purging frequency can be determined according to the working conditions, such as flue gas humidity and particulate matter. In the case of very low levels, it can generally be set to purge once every 4 hours. The timer 3 19-3 is used to control the opening and closing of the solenoid valve 3 22 and the timer 4 19-4 is used to control the opening and closing of the solenoid valve 4 23. When the solenoid valve 1 20 and the solenoid valve 2 21 are in the closed state, the Open solenoid valve three 22 and solenoid valve four 23; on the contrary, when solenoid valve one 20 and solenoid valve two 21 are in the open state, close solenoid valve three 22 and solenoid valve four 23.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection of the utility model.

Claims (6)

1. A temperature control heat tracing pitot tube comprises a full pressure measuring tube and a back pressure measuring tube, wherein one end of the full pressure measuring tube is connected with a full pressure joint, the other end of the full pressure measuring tube is provided with a full pressure measuring hole, one end of the backpressure measuring pipe is connected with the backpressure joint, the other end of the backpressure measuring pipe is provided with a backpressure measuring hole, it is characterized in that the full-pressure measuring tube and the back pressure measuring tube are respectively wrapped with a heating film and an insulating layer in turn, the insulating layers of the full-pressure measuring tube and the back pressure measuring tube are wrapped with a heat insulating layer, a protective shell is arranged outside the heat insulation layer, at least one temperature probe penetrates through the side wall of the protective shell and extends into the heat insulation layer, the measuring end of the temperature probe is close to the mutual contact part of the insulating layers of the full pressure measuring tube and the back pressure measuring tube, and one end of the full-pressure joint far away from the full-pressure measuring pipe, one end of the back-pressure joint far away from the back-pressure measuring pipe and one end of the temperature probe far away from the measuring end of the back-pressure measuring pipe are connected with an online monitoring instrument.

2. The temperature-controlled heat tracing pitot tube according to claim 1, wherein a temperature display, a pressure display, a full pressure interface, a back pressure interface, a temperature probe interface and a purging gas source interface are arranged outside the on-line monitoring instrument, a first differential pressure transmitter, a second differential pressure transmitter, a first timer, a second timer, a third timer, a fourth timer, a first electromagnetic valve, a second electromagnetic valve, a third electromagnetic valve and a fourth electromagnetic valve are arranged inside the on-line monitoring instrument, one end of the temperature probe far away from the measuring end is connected with the temperature probe interface, the temperature probe interface is connected with the temperature display, one end of the full pressure joint far away from the full pressure measuring tube is connected with the full pressure interface, the full pressure interface is connected with the input end of the first differential pressure transmitter through a third pipeline, a third electromagnetic valve and a third timer are arranged on the third pipeline, one end of the back pressure joint far away from the back pressure measuring tube is connected with the back, the back pressure interface is connected with the input end of the second differential pressure transmitter through the fourth pipeline, the fourth pipeline is provided with a fourth electromagnetic valve and a fourth timer, the output end of the first differential pressure transmitter and the output end of the second differential pressure transmitter are both connected with the pressure display, one end of the purging gas source interface is connected with an external gas source, the other end of the purging gas source interface is simultaneously communicated with the third pipeline through the first pipeline, and is communicated with the fourth pipeline through the second pipeline, the first pipeline is provided with a first electromagnetic valve and a first timer, and the second pipeline is provided with a second electromagnetic valve and a second timer.

3. The temperature controlled heat tracing pitot tube of claim 2, wherein the third solenoid valve and the third timer are both located between the first differential pressure transmitter and the junction of the first pipeline and the third pipeline, and the fourth solenoid valve and the fourth timer are both located between the second differential pressure transmitter and the junction of the second pipeline and the fourth pipeline.

4. The temperature controlled heat tracing pitot tube of claim 1, wherein the heating film is a polyimide thin film PI electrothermal film.

5. The temperature controlled heat tracing pitot tube of claim 1, wherein the insulating layer is silicone rubber, asbestos, or mica board.

6. The temperature-controlled heat tracing pitot tube of claim 1, wherein the thermal insulation layer is fiberglass cotton felt, polyurethane foam or rock wool.