Electric heat tracing monitoring system

Abstract

The utility model relates to the technical field of electric power generation, in particular to an electric heat tracing monitoring system. Comprising a plurality of temperature controllers arranged in an instrument heat preservation box and used for obtaining corresponding instrument conduit temperatures; the data input end of the master control device is in communication connection with each temperature controller, and the control signal output end of the master control device is in communication connection with the electric tracing band working power supply corresponding to each temperature controller. A hardware connection framework of a plurality of temperature controllers and a main control device is arranged, a traditional temperature control mode depending on manual operation is converted into an automatic power supply control mechanism based on a preset temperature threshold value, and independent monitoring and control of each instrument conduit are achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power generation, in particular to an electric heat tracing monitoring system. BACKGROUND

[0002] The boiler of a thermal power plant is prone to freezing of the instrument conduit in winter, which affects the normal operation of the equipment. To solve this problem, laying electric heat tracing tape to maintain the instrument conduit in a relatively stable temperature environment has become an extremely important task.

[0003] The existing electric heat tracing system can only observe the temperature of the instrument conduit through the local temperature controller, manually set the power of the electric heat tracing tape, and manually switch the power supply of the electric heat tracing tape. It cannot monitor the operating parameters of each instrument conduit on the distributed control system (DCS). With the increasing demand for intelligence in thermal power plants, the demand for intelligent monitoring and control of the electric heat tracing system is becoming increasingly urgent. SUMMARY

[0004] Therefore, the embodiments of the present application provide an electric heat tracing monitoring system to solve the problem that the existing electric heat tracing system cannot realize intelligent monitoring and control.

[0005] The first aspect of the embodiments of the present application provides an electric heat tracing monitoring system, comprising:

[0006] A plurality of temperature controllers are arranged in the instrument heat preservation box and are used to obtain the temperature of the corresponding instrument conduit;

[0007] A main control device is in communication connection with each temperature controller at the data input end and is in communication connection with the corresponding electric heat tracing tape power supply at the control signal output end.

[0008] The main control device is configured to send an opening or closing control signal to the corresponding electric heat tracing tape power supply based on the comparison relationship between the instrument conduit temperature output by each temperature controller and the preset starting temperature.

[0009] More preferably, it further comprises a warning device, and the output end of the main control device is in communication connection with the input end of the warning device.

[0010] The main control device is further configured to output a warning signal to the warning device based on the comparison relationship between the instrument conduit temperature output by each temperature controller and the preset warning temperature.

[0011] More preferably, the main control device comprises a first temperature comparison circuit and a first relay driving module.

[0012] The first temperature comparison circuit comprises a first multiplexing analog switch and a first voltage comparator array, the input end of each analog switch in the first multiplexing analog switch is connected to the temperature signal output end of a corresponding temperature controller, the output end of each analog switch is respectively connected to the non-inverting input end of a corresponding comparator in the first voltage comparator array, the inverting input end of the comparator is respectively connected to a first adjustable reference voltage source, the output end of the comparator is connected to the input end of the first relay drive module, and the output end of the first relay drive module is connected to a corresponding electric heat tracing band working power supply.

[0013] More preferably, the first relay drive module comprises an optocoupler isolator and a freewheeling diode, the input end of the optocoupler isolator is connected to the output end of the comparator as the input end of the relay drive module, and the output end of the optocoupler isolator is connected to the corresponding electric heat tracing band working power supply through the freewheeling diode.

[0014] More preferably, the main control device comprises a second temperature comparison circuit and a second relay drive module.

[0015] The second temperature comparison circuit comprises a second multiplexing analog switch and a second voltage comparator array, the input end of each analog switch in the second multiplexing analog switch is connected to the temperature signal output end of a corresponding temperature controller, the output end of each analog switch is respectively connected to the non-inverting input end of a corresponding comparator in the second voltage comparator array, the inverting input end of the comparator is respectively connected to a second adjustable reference voltage source, the output end of the comparator is connected to the input end of the second relay drive module, and the output end of the second relay drive module is connected to the early warning device.

[0016] More preferably, the second relay drive module comprises a multi-channel optocoupler isolator, a Darlington transistor group and a state latch.

[0017] The input end of the multi-channel optocoupler isolator is connected to the output end of the second voltage comparator array, the base of the Darlington transistor group is connected to the output end of the multi-channel optocoupler isolator through a current limiting resistor, the input end of the state latch is connected to the collector of the Darlington transistor group, and the output end of the state latch is connected to the input end of the early warning device.

[0018] More preferably, the main control device further comprises a hysteresis feedback resistor, and the hysteresis feedback resistor is connected between the output end and the non-inverting input end of the comparator.

[0019] More preferably, the main control device is further connected with a decentralized control device.

[0020] The electric heat tracing monitoring system of the embodiment of the present application is provided with multiple temperature controllers arranged in the instrument heat preservation box to obtain corresponding instrument pipe temperatures; the main control device is in communication connection with each temperature controller at the data input end and in communication connection with the corresponding electric heat tracing belt working power supply at the control signal output end; the main control device is configured to send an opening or closing control signal to the corresponding electric heat tracing belt working power supply based on the comparison relationship between the instrument pipe temperature output by each temperature controller and the preset starting temperature. The hardware connection architecture of the multiple temperature controllers and the main control device is set to convert the traditional temperature control mode relying on manual operation into an automatic power control mechanism based on the preset temperature threshold. The advantage is that the real-time comparison between the temperature signal and the preset starting temperature is directly realized by the hardware circuit, the electric heat tracing belt power supply is driven by the physical relay, the independent monitoring and control of each instrument pipe are realized by the dispersedly arranged temperature controllers, and the problem that the existing technology cannot realize multi-point accurate temperature control is solved. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 is a connection diagram of the electric heat tracing monitoring system provided by an embodiment of the present application;

[0023] Figure 2 is a connection diagram of the main control device provided by an embodiment of the present application;

[0024] Figure 3 is a connection diagram of the electric heat tracing belt working power supply provided by an embodiment of the present application;

[0025] Figure 4 is a connection diagram of the early warning device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0026] In the following description, specific details such as specific system structures, techniques, etc. are presented in order to thoroughly understand the embodiments of the present application. However, it should be clear to those skilled in the art that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits and methods are omitted to avoid unnecessary details that hinder the description of the present application.

[0027] It should be understood that the term "include" as used in the specification and the appended claims indicates the presence of the described features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0028] It should also be understood that the term "and / or" as used in the specification and the appended claims, means any one of the associated listed items, as well as all possible combinations of the items, and includes the combinations.

[0029] In addition, in the description of the specification and the appended claims, the terms "first", "second", "third", etc. are only used for differentiation of description, and cannot be understood as indicating or implying relative importance.

[0030] In the present specification, the phrase "one embodiment" or "some embodiments" etc. means that the specific feature, structure or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Therefore, the phrases "in one embodiment", "in some embodiments", "in other some embodiments", "in further some embodiments" etc. appearing in different places in the specification are not necessarily all referring to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "include", "contain", "have" and their variations mean "including but not limited to", unless otherwise specifically emphasized.

[0031] As shown in Figure 1 The electric heat tracing monitoring system provided by the embodiments of the present application comprises an electric heat tracing monitoring system, which comprises:

[0032] A plurality of temperature controllers 1 are arranged in the instrument heat preservation boxes, and are used to obtain corresponding instrument conduit temperatures;

[0033] A main control device 2 is in communication connection with each temperature controller 1 at a data input end, and is in communication connection with a corresponding electric heat tracing belt working power supply 4 of each temperature controller 1 at a control signal output end;

[0034] The main control device 2 is configured to send an opening or closing control signal to the corresponding electric heat tracing belt working power supply 4 based on a comparison relationship between the instrument conduit temperature output by each temperature controller 1 and a preset starting temperature.

[0035] In application, the plurality of temperature controllers 1 are arranged in the respective instrument heat preservation boxes 10, and the plurality of temperature controllers 1 jointly form a temperature acquisition unit 100 of the system. The temperature acquisition unit 100 is used to collect the temperature of the instrument conduit, and then sends the collected temperature value to the main control device 2 (i.e. the electric heat tracing intelligent control system), and the temperature controller 1 and the electric heat tracing intelligent control system are in communication connection.

[0036] In the application, a plurality of pressure transmitters are arranged in each instrument incubator. In order to ensure that the instrument pipes connected with the pressure transmitters are not frozen in winter, one electric heating cable is laid on each instrument pipe, and the heating cable is started to heat the instrument pipe when the ambient temperature is low. The temperature controller is used to control the heating power of the heating cable, and one temperature controller is needed for each instrument pipe. A large thermal power generating unit usually needs to be provided with 200 to 300 pressure transmitters, and each pressure transmitter is arranged in the instrument incubator in situ. The corresponding temperature controller is also arranged in the corresponding instrument incubator. One instrument incubator usually arranges 3 to 6 pressure transmitters, and therefore the temperature controller also needs to be arranged in multiple groups according to the arrangement scheme of the pressure transmitters. The temperature controller 1 shell is fixed on the outer wall of each instrument pipe of the instrument incubator 10 by means of a stainless steel clamp (material 304, width 15 mm), and the contact surface with the pipe is coated with heat-conducting silicone grease.

[0037] The plurality of temperature controllers and the hardware connection architecture of the main control device are arranged in the embodiment of the application, so that the traditional temperature control mode depending on manual operation is converted into an automatic power control mechanism based on a preset temperature threshold. The advantage is that the real-time comparison of the temperature signal and the preset starting temperature is directly realized by the hardware circuit, the power of the electric heating cable is driven by the physical relay, the system response delay and the program error risk caused by the traditional software algorithm are avoided, and the independent monitoring and control of each instrument pipe are realized by the dispersedly arranged temperature controllers, so that the problem that the existing technology cannot realize accurate multi-point temperature control is fundamentally solved, and the hardware structure characteristics of the utility model protection object are met.

[0038] In one embodiment, the main control device 2 is also connected with a decentralized control device.

[0039] In the application, the main control device 2 and the decentralized control device (DCS) are connected in communication through the Modbus RTU communication protocol, for obtaining various data in the main control device 2, and also for actively sending the electric heating cable working power switching and parameter setting instructions to the main control device 2.

[0040] In one embodiment, the output end of the main control device 2 is in communication connection with the input end of the early warning device 5.

[0041] The main control device 2 is also configured to output the early warning signal to the early warning device 5 based on the comparison relationship between the instrument pipe temperature output by each temperature controller 1 and the preset early warning temperature.

[0042] The embodiment of the application builds a double-layer protection mechanism by adding the early warning device and the linkage control of the main control device. Through the physical connection of the second temperature comparison circuit and the early warning device, the real-time performance and the non-tamperability of the over-temperature alarm signal generation are ensured, and the prevention ability of the instrument pipe temperature out-of-control risk in the high-risk environment of the thermal power plant is improved.

[0043] In one embodiment, as shown in Figure 2 The master device 2 includes a first temperature comparison circuit 21 and a first relay drive module 22.

[0044] The first temperature comparison circuit 21 includes a first multi-channel analog switch 211 and a first voltage comparator array 212. The input end of each channel of the first multi-channel analog switch 211 is connected to the temperature signal output end of the corresponding temperature controller 1. The output end of each channel is connected to the non-inverting input end of the corresponding comparator in the first voltage comparator array 212. The inverting input end of the comparator is connected to the first adjustable reference voltage source. The output end of the comparator is connected to the input end of the first relay drive module 22. The output end of the first relay drive module 22 is connected to the corresponding electric heat tracing band power supply 4.

[0045] In application, the first multi-channel analog switch 211 can use CD4051BE, an 8-channel single-ended analog switch. The first voltage comparator array 212 can use LM2903 dual comparators, each channel is independently configured.

[0046] The embodiment of the present application realizes parallel processing of multi-channel temperature signals by using the hardware combination of the first temperature comparison circuit and the relay drive module, and through the cooperative work of the multi-channel analog switch and the voltage comparator array. The adjustable reference voltage source sets differentiated start / stop temperature thresholds, so that each temperature controller corresponding to the electric heat tracing band has independent regulation and control capability. At the same time, the nanosecond-level response speed of the hardware comparator far exceeds the millisecond-level processing period of the traditional PLC program, which is especially suitable for the sudden cooling scene of the instrument conduit of the thermal power plant, and effectively prevents freezing accidents.

[0047] In one embodiment, as shown in Figure 3 The first relay drive module 22 includes an optocoupler 221 and a freewheeling diode 222. The input end of the optocoupler 221 is connected to the output end of the comparator as the input end of the relay drive module 22. The output end of the optocoupler 221 is connected to the corresponding electric heat tracing band power supply 4 through the freewheeling diode 222.

[0048] In application, the optocoupler 221 can use TLP521-2 dual-channel optocoupler.

[0049] The application embodiment forms double protection in electrical isolation and surge suppression through the driving module composed of the optical coupling isolator and the freewheeling diode. The optical coupling isolator cuts off the direct electrical connection between the master control circuit and the high-voltage load, avoiding the electromagnetic interference generated when the electric heat tracing band starts and stops from affecting the temperature signal acquisition accuracy; the freewheeling diode eliminates the reverse electromotive force generated when the relay coil is powered off, prolonging the relay contact life. This hardware design significantly improves the long-term operation stability of the system in a strong electromagnetic interference environment.

[0050] In one embodiment, as shown in Figure 4 The master control device 2 includes a second temperature comparison circuit 23 and a second relay driving module 24.

[0051] The second temperature comparison circuit 23 includes a second multi-channel analog switch 231 and a second voltage comparator array 232. The input end of each analog switch in the second multi-channel analog switch 231 is connected to the temperature signal output end of the corresponding temperature controller 1, the output end of each analog switch is respectively connected to the non-inverting input end of the corresponding comparator in the second voltage comparator array 232, the inverting input end of the comparator is respectively connected to the second adjustable reference voltage source, and the output end of the comparator is connected to the input end of the second relay driving module 24. The output end of the second relay driving module 24 is connected to the pre-warning device 5.

[0052] The application embodiment designs a second temperature comparison circuit, adopts a hardware architecture physically separated from the master control circuit. Through independent multi-channel analog switches and voltage comparator arrays, parallel judgment of the early warning threshold is realized, avoiding the alarm function failure caused by the master control circuit failure. In particular, the second adjustable reference voltage source allows independent setting of the early warning temperature value, forming an early warning mechanism prior to power cut-off, which gives the operating personnel time to handle the fault. This hierarchical early warning hardware implementation significantly improves the active protection capability of the system.

[0053] In one embodiment, the second relay driving module 24 includes a multi-channel optical coupling isolator 241, a Darlington transistor group 242, and a state latch 243.

[0054] The input end of the multi-channel optical coupling isolator 241 is connected to the output end of the second voltage comparator array 232, the base of the Darlington transistor group 242 is connected to the output end of the multi-channel optical coupling isolator 241 through a current limiting resistor, the input end of the state latch 243 is connected to the collector of the Darlington transistor group 242, and the output end of the state latch 243 is connected to the input end of the pre-warning device 5.

[0055] The application embodiment realizes synchronous driving and state latching of multiple alarm signals through the combination design of the multi-channel optical coupling isolator and the Darlington transistor group. The Darlington transistor group provides sufficient driving current to ensure the reliable operation of the alarm device, and the state latch stores the alarm state through the hardware circuit, so that the alarm indication is still maintained even if the temperature temporarily falls back, the continuous warning can be provided when the system communication is interrupted, and the safety guarantee capability in extreme working conditions is significantly enhanced.

[0056] In one embodiment, the main control module 2 is also provided with a storage display unit for storing and displaying the working state of the temperature controller and the corresponding identification and working time.

[0057] In one embodiment, the main control device 2 further comprises a hysteresis feedback resistor, which is connected across the output and the non-inverting input of the comparator.

[0058] The application embodiment introduces a hysteresis feedback resistor in the comparator circuit to construct a temperature comparator with Schmitt trigger characteristics. The hysteresis interval of temperature control is set by hardware, which fundamentally eliminates the problem of frequent relay jitter near the critical temperature point. The hysteresis characteristics realized by pure hardware are not only faster in response speed than the software anti-jitter algorithm, but also can avoid control failure caused by program runaway, and are particularly suitable for the working conditions of the thermal power plant environment temperature fluctuation, to ensure the stable and reliable switching action of the electric heat tracing band power supply.

[0059] The working principle of the system is as follows:

[0060] When the system works, each temperature controller 1 collects temperature signals in real time through the PT100 platinum resistance (the installation distance is ≤15 cm) close to the instrument conduit, and converts the temperature signals into 0-5V voltage signals through the three-wire constant current source circuit. The first multi-channel analog switch 211 connects the temperature signals of each channel to the first voltage comparator array 212 in turn in the time division multiplexing mode (the scanning period is <10 ms). The first reference voltage preset at the inverting input of each comparator corresponds to the electric heat tracing band starting threshold value, when the temperature is lower than the set value, the comparator outputs high level, triggers the optical coupling isolator 221 to conduct, so as to drive the intermediate relay (the contact capacity is 10A / 250VAC) to attract and connect the corresponding electric heat tracing band power supply 4.

[0061] The second temperature comparison circuit 23 adopts an independently powered LM339 comparator group, and the reference voltage is set as the early warning threshold value. When the temperature is out of limit, the second temperature comparison circuit 23 outputs high level, the Darlington transistor group is turned on and triggers the RS latch (CD4043BE) to set, locks the alarm state, and triggers the buzzer to alarm. Even if the temperature falls back, the buzzer still alarms continuously, and can be cleared through the manual reset button.

[0062] The above examples are only used to illustrate the technical solutions of the present application, but not limit the same; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalent ones; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should be included in the protection scope of the present application.

Claims

1. An electrical heat trace monitoring system, characterized by, The utility model relates to a kind of temperature control device for instrument, including: Multiple temperature controllers (1) are arranged in the instrument incubator, for obtaining corresponding instrument conduit temperature; A master control device (2) is connected with each temperature controller (1) in communication, and the control signal output end is connected with the corresponding electric heat tracing band power supply (4) of each temperature controller (1) in communication.

2. The electrical heat trace monitoring system of claim 1, wherein, It also includes a warning device (5), and the output end of the master control device (2) is connected with the input end of the warning device (5) in communication. The master control device (2) is configured to output a warning signal to the warning device (5) based on the comparison between the instrument conduit temperature output by each temperature controller (1) and the preset warning temperature.

3. The electrical heat trace monitoring system of claim 1, wherein: The master control device (2) includes a first temperature comparison circuit (21) and a first relay drive module (22). The first temperature comparison circuit (21) includes a first multiplex analog switch (211) and a first voltage comparator array (212). The input end of each analog switch in the first multiplex analog switch (211) is connected to the temperature signal output end of the corresponding temperature controller (1). The output end of each analog switch is connected to the non-inverting input end of the corresponding comparator in the first voltage comparator array (212). The inverting input end of the comparator is connected to a first adjustable reference voltage source. The output end of the comparator is connected to the input end of the first relay drive module (22). The output end of the first relay drive module (22) is connected to the corresponding electric heat tracing band power supply (4).

4. The electrical heat trace monitoring system of claim 3, wherein: The first relay drive module (22) includes an optocoupler isolator (221) and a freewheeling diode (222). The input end of the optocoupler isolator (221) is connected to the output end of the comparator as the input end of the relay drive module (22). The output end of the optocoupler isolator (221) is connected to the corresponding electric heat tracing band power supply (4) through the freewheeling diode (222).

5. The electrical heat trace monitoring system of claim 2, wherein: The master control device (2) includes a second temperature comparison circuit (23) and a second relay drive module (24). The second temperature comparison circuit (23) includes a second multiplex analog switch (231) and a second voltage comparator array (232). The input end of each analog switch in the second multiplex analog switch (231) is connected to the temperature signal output end of the corresponding temperature controller (1). The output end of each analog switch is connected to the non-inverting input end of the corresponding comparator in the second voltage comparator array (232). The inverting input end of the comparator is connected to a second adjustable reference voltage source. The output end of the comparator is connected to the input end of the second relay drive module (24). The output end of the second relay drive module (24) is connected to the warning device (5).

6. The electrical heat trace monitoring system of claim 5, wherein: The second relay drive module (24) includes a multi-channel optocoupler isolator (241), a Darlington transistor group (242), and a state latch (243). The input end of the multi-channel photo-coupling isolator (241) is connected with the output end of the second voltage comparator array (232), the base of the Darlington transistor group (242) is connected with the output end of the multi-channel photo-coupling isolator (241) through a current-limiting resistor, the input end of the state latch (243) is connected with the collector of the Darlington transistor group (242), and the output end of the state latch (243) is connected with the input end of the early warning device (5).

7. The electrical heat trace monitoring system of claim 3, wherein: The master control device (2) further comprises a hysteresis feedback resistor connected between the output end and the non-inverting input end of the comparator.

8. The electrical heat trace monitoring system of claim 1, wherein: The master control device (2) is further connected with a decentralized control device.

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