Constant temperature and constant pressure circulating water control system

Abstract

The application relates to the technical field of circulating water control, and discloses a constant-temperature and constant-pressure circulating water control system, which comprises a water-using pipe network, a water-supply pipe network and an electrical control system, the water-using pipe network comprises a plurality of user terminals, a first circulating water pump group, a first pressure sensor and a first temperature sensor located at the outlet of the first circulating water pump group, a second temperature sensor located downstream of the plurality of user terminals and a first electric valve, the water-supply pipe network comprises a second circulating water pump group for supplying a hot water source, third and fourth temperature sensors at a hot water supply position and a backwater position and a third electric valve, the water-using pipe network and the water-supply pipe network are connected with a second electric valve and a fourth electric valve respectively, the electrical control system is electrically connected with the pressure sensor, the temperature sensor, the electric valve and the circulating water pump group, and the electric valve and the circulating water pump group are controlled according to signals collected by the pressure sensor and the temperature sensor, so that constant-temperature control and constant-pressure control of the circulating water system are realized.

Description

Technical Field

[0001] This application relates to the field of circulating water control, and in particular to a constant temperature and pressure circulating water control system. Background Technology

[0002] With the increasing demands for stability in hot water supply and circulating water systems in hotels, hospitals, schools, residential communities, and industrial production facilities, constant temperature and pressure circulating water systems are widely used in domestic hot water supply and industrial circulating water systems. Circulating water systems maintain stable water temperature and supply pressure within the pipe network, thereby improving user comfort and system reliability.

[0003] Existing constant temperature and pressure circulating water electrical and electronic control systems are often complex in structural design, with some systems having redundant functions and a large number of control components, resulting in high equipment costs. At the same time, different application scenarios require separate design based on the number of water pumps and the pipeline structure, resulting in poor system compatibility and greater difficulty in installation and maintenance.

[0004] Therefore, how to provide a circulating water control system with a relatively simple structure, reliable control, the ability to simultaneously achieve constant temperature and constant pressure control, and good adaptability and energy-saving effect has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this application is to provide a constant temperature and pressure circulating water control system that can realize local manual or automatic constant temperature and pressure circulating water control. The whole system has a simple structure, is easy to operate, takes into account energy saving and safety, and has a good practical effect.

[0006] This application discloses a constant temperature and pressure circulating water control system, including a water supply network, a water supply network, and an electrical control system for controlling the water circulation of the water supply network and the water supply network; The water supply network includes several user terminals, a first circulating water pump group, a first pressure sensor and a first temperature sensor located at the outlet of the first circulating water pump group, a second temperature sensor located downstream of the several user terminals, and a first electric valve. The water supply network includes a second circulating water pump set for supplying hot water, a third temperature sensor at the hot water supply point, a fourth temperature sensor at the hot water return point, and a third electric valve. A second electric valve and a fourth electric valve are respectively connected between the water supply network and the water usage network; The electrical control system is electrically connected to each pressure sensor, each temperature sensor, each electric valve, and each circulating water pump group, and controls each electric valve and each circulating water pump group based on the signals collected by each pressure sensor and each temperature sensor to achieve constant temperature and constant pressure control of the circulating water system, wherein: When the temperature difference between the first temperature sensor and the second temperature sensor is not lower than the first temperature difference setting value and the pressure signal collected by the first pressure sensor is not lower than the first pressure setting value, the first electric valve opens, the second electric valve and the fourth electric valve close, the first circulating water pump group works, and the water circulation of the water supply network is started to maintain the temperature and pressure stability of the user terminal. When the difference between the temperature signals collected by the first temperature sensor and the second temperature sensor is lower than the first temperature difference set value and / or the pressure signal collected by the first pressure sensor is lower than the first pressure set value, the first electric valve and the third electric valve are closed, the second electric valve and the fourth electric valve are opened, the first circulating water pump group and the second circulating water pump group are working, and the water circulation between the water supply network and the water supply pipeline is started. When the temperature difference between the third temperature sensor and the fourth temperature sensor is lower than the second temperature difference set value, the third electric valve opens, the second electric valve and the fourth electric valve close, the second circulating water pump group starts working, and the water circulation of the water supply network is started to maintain the temperature stability of the water supply network.

[0007] In a preferred embodiment, the water supply network further includes: a water replenishment pump group located at the hot water return point for making room temperature water replenishment, and a second pressure sensor located at the outlet of the water replenishment pump group; when the pressure signal collected by the second pressure sensor is lower than the second pressure set value, the second circulating water pump group and the water replenishment pump group operate to maintain the pressure stability of the water supply network.

[0008] In a preferred embodiment, the first circulating water pump group is composed of a first circulating water pump and a second circulating water pump connected in parallel, the second circulating water pump group is composed of a third circulating water pump and a fourth circulating water pump connected in parallel, and the makeup water pump group is composed of a fifth circulating water pump and a sixth circulating water pump connected in parallel.

[0009] In a preferred embodiment, the electrical control system further includes: first to eighth circuit breakers, first to eighth AC contactors, first to sixth thermal relays, and a frequency converter; The output terminal of the first circuit breaker is connected to the first AC contactor, the output terminal of the first AC contactor is connected to the first thermal relay, and the output terminal of the first thermal relay is connected to the first circulating water pump; the output terminal of the second circuit breaker is connected to the second AC contactor, the output terminal of the second AC contactor is connected to the second thermal relay, and the output terminal of the second thermal relay is connected to the second circulating water pump; the output terminal of the third circuit breaker is connected to the third AC contactor, the output terminal of the third AC contactor is connected to the third thermal relay, and the output terminal of the third thermal relay is connected to the third circulating water pump; the output terminal of the fourth circuit breaker is connected to the fourth AC contactor, the output terminal of the fourth AC contactor is connected to the fourth thermal relay, and the output terminal of the fourth thermal relay is connected to the fourth circulating water pump; the fifth circuit breaker... The output terminals of the circuit breaker are connected to the fifth AC contactor, the output terminals of the fifth AC contactor are connected to the fifth thermal relay, and the output terminals of the fifth thermal relay are connected to the fifth circulating water pump; the output terminals of the sixth circuit breaker are connected to the seventh AC contactor, the output terminals of the seventh AC contactor are connected to the sixth thermal relay, and the output terminals of the sixth thermal relay are connected to the sixth circulating water pump; the output terminals of the seventh circuit breaker are connected to the frequency converter, the output terminals of the frequency converter are connected to the sixth AC contactor and the eighth AC contactor respectively, the output terminals of the sixth AC contactor are connected to the fifth circulating water pump, and the output terminals of the eighth AC contactor are connected to the sixth circulating water pump; the output terminals of the eighth circuit breaker are connected to the power supply terminals of the first electric valve, the second electric valve, the third electric valve, and the fourth electric valve respectively.

[0010] In a preferred embodiment, the electrical control system further includes: a fuse, and first to twelfth intermediate relays; The incoming terminal of the eighth circuit breaker is connected to the live wire, and the outgoing terminals of the eighth circuit breaker are respectively connected to the common terminal of the normally open and normally open contacts of the first to fourth intermediate relays; the other end of the normally open contact of the first intermediate relay is connected to the valve opening control circuit of the first electric valve, and its valve opening limit and valve closing limit are respectively connected to one end of the control coil of the fifth and sixth intermediate relays; the other end of the normally open contact of the second intermediate relay is connected to the valve opening control circuit of the second electric valve, and its valve opening limit and valve closing limit are respectively connected to one end of the control coil of the seventh and eighth intermediate relays; the other end of the normally open contact of the third intermediate relay is connected to the valve opening control circuit of the third electric valve, and its valve opening limit and valve closing limit are respectively connected to the control coil of the ninth and tenth intermediate relays; the other end of the normally open contact of the fourth intermediate relay is connected to the valve opening control circuit of the fourth electric valve, and its valve opening limit and valve closing limit are respectively connected to one end of the control coil of the eleventh and twelfth intermediate relays; the other ends of the control coils of the fifth to twelfth intermediate relays are connected to the neutral wire of the control circuit.

[0011] In a preferred embodiment, the electrical control system further includes: a programmable controller, an analog module, a touch screen, a selector switch, first and second pressure transmitters, and first to fourth temperature transmitters; The fuse's input terminal is connected to the live wire, and its output terminal is connected to the power supply terminal of the programmable controller (PLC). The PLC's ground terminal is connected to the first indicator light and the live wire terminal of the switching power supply. The output terminal of the switching power supply is connected to the touch screen, the first and second pressure transmitters, and the first to fourth temperature transmitters. The output terminals of the second pressure transmitter and the first to fourth temperature transmitters are connected to the analog module. The selector switch, the normally open contacts of the first to eighth AC contactors, the normally open contacts of the first to sixth thermal relays, and the normally open contacts of the fifth to twelfth intermediate relays are respectively connected to the first to twentieth digital input terminals of the PLC. The output terminals of the first to eleventh relays of the PLC are respectively connected to the control coils of the first to eighth AC contactors and the control coils of the first to fourth intermediate relays. The other end of the control coils of the first to eighth AC contactors and the control coils of the first to fourth intermediate relays are connected to the neutral wire. The PLC's RJ45 communication interface is connected to the touch screen, and the PLC's Port1 communication interface communicates with the frequency converter.

[0012] In a preferred embodiment, the electrical control system further includes: a first to an eighth varistor, the two ends of which are respectively connected to the two ends of the control coil of a first to an eighth AC contactor.

[0013] In a preferred embodiment, the electrical control system further includes: first to sixth indicator lights and an audible and visual alarm, wherein the output terminals of the twelfth to eighteenth relays of the programmable controller are respectively connected to the second to sixth indicator lights and the audible and visual alarm, and the other end of the second to sixth indicator lights and the audible and visual alarm is connected to the neutral wire (N).

[0014] In a preferred embodiment, the water supply network further includes a first overpressure relief valve and a first automatic air release valve disposed at a high position on the water supply side of the network.

[0015] In a preferred embodiment, the water supply network further includes a second overpressure relief valve and a second automatic air release valve located at a high position on the water supply side of the network.

[0016] It should be understood that, within the scope of this invention, the above-described technical features of this invention and the technical features specifically described below (such as in the embodiments) can be combined with each other to form new or preferred technical solutions. Due to space limitations, they will not be described in detail here. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. It should be understood that the accompanying drawings described below are merely some implementation examples of the present invention, and those skilled in the art can obtain other implementation examples based on these drawings without creative effort.

[0018] Figure 1 This is a process flow diagram of a circulating water control system according to one embodiment of this application.

[0019] Figure 2 This is an electrical schematic diagram of the primary circuit of electrical control according to one embodiment of this application.

[0020] Figure 3 This is an electrical schematic diagram of the electrical control secondary circuit according to one embodiment of this application.

[0021] Figure 4 This is an electrical schematic diagram of the electrical control secondary circuit according to another embodiment of this application.

[0022] Figure 5 This is an electrical schematic diagram of the electrical control secondary circuit according to another embodiment of this application.

[0023] In each of the attached figures, the figure labels are as follows: QF11~QF18 Circuit Breaker 1~Circuit Breaker 8 FU1 fuse KM1~KM8 First AC Contactor~Eighth AC Contactor KH1~KH6 First thermal relay~Eighth thermal relay VFD frequency converter PLC (Programmable Logic Controller) EM analog module HMI Touchscreen S Switching power supply KA1~KA12 First Intermediate Relay~Twelfth Intermediate Relay SA1 Selector Switch HL1~HL6 First indicator light~Sixth indicator light HL7 Audible and Visual Alarm U1~U8 Varistors PT1~PT2 First Pressure Transmitter~Second Pressure Transmitter TT1~TT2 First Temperature Transmitter~Sixth Temperature Transmitter Detailed Implementation

[0024] In the following description, many technical details are presented to help the reader better understand this application. However, those skilled in the art will understand that the technical solutions claimed in this application can be implemented even without these technical details and various variations and modifications based on the following embodiments.

[0025] Through extensive and in-depth research, the inventors have proposed a constant temperature and pressure circulating water control system. This system combines water supply and drainage networks in a structured manner, and utilizes multiple electric valves to automatically switch between large and small circulation modes. Simultaneously, temperature and pressure sensors monitor system operating parameters in real time. A programmable logic controller (PLC) coordinates the control of the circulating water pumps, electric valves, and frequency converters based on temperature differences and pressure setpoints, achieving combined regulation of constant temperature and pressure in the circulating water system. Furthermore, constant pressure water replenishment is achieved by controlling the speed of the makeup water pump using a frequency converter. The system employs multiple pumps operating alternately and a backup structure, improving the stability and reliability of system operation. RS485 communication is used to monitor and manage equipment operating status, making the entire system characterized by relatively simple structure, high control precision, strong adaptability, and good energy-saving effects.

[0026] This application has at least the following beneficial effects and advantages: (b) By setting the parameters of the frequency converter, the water pump is protected against overload, overcurrent, overvoltage, undervoltage, and phase loss, so as to avoid damage to the water pump motor, etc. (c) By switching between small and large circulation systems, the control is more precise and has a strong adaptive capability; (d) Through RS485 communication, the programmable controller can monitor the real-time status of the frequency converter and perform accurate diagnostics, providing reliable data for water pump control and maintenance; (e) Based on the parameter settings on the touch screen, and combined with the control logic of the programmable controller and the frequency converter, the system is precisely controlled for constant temperature and constant pressure.

[0027] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0028] The first embodiment of this application relates to a constant temperature and pressure circulating water control system, the process flow diagram of which is as follows: Figure 1 As shown, the constant temperature and pressure circulating water control system includes a water supply network, a water supply network, and an electrical control system for controlling the water circulation of the water supply network and the water supply network.

[0029] The water supply network includes several user terminals, a first circulating water pump set, a first pressure sensor (e.g., pressure sensor 1) and a first temperature sensor (e.g., temperature sensor 1) located at the outlet of the first circulating water pump set, a second temperature sensor (e.g., temperature sensor 2) located downstream of the user terminals, and a first electric valve (e.g., electric valve 1). The water supply network includes a second circulating water pump set supplying hot water, a third temperature sensor (e.g., temperature sensor 3) at the hot water supply point, a fourth temperature sensor (e.g., temperature sensor 4) at the hot water return point, and a third electric valve (electric valve 3). The water supply network also includes a second pressure sensor (e.g., pressure sensor 2) located at the outlet of the second circulating water pump set, and a makeup water pump set for replenishing water at ambient temperature. A second electric valve (electric valve 2) and a fourth electric valve (electric valve 4) are connected between the water supply network and the water supply network, respectively. The water supply network and the water supply network each form a small circulation system, and when the water supply network and the water supply network are fluidly connected, they form a large circulation system.

[0030] The first circulating water pump group consists of a first circulating water pump (e.g., pump 1) and a second circulating water pump (e.g., pump 2) connected in parallel; the second circulating water pump group consists of a third circulating water pump (e.g., pump 3) and a fourth circulating water pump (e.g., pump 4) connected in parallel; and the makeup water pump group consists of a fifth circulating water pump (e.g., pump 5) and a sixth circulating water pump (e.g., pump 6) connected in parallel.

[0031] The electrical control system is electrically connected to each pressure sensor, temperature sensor, electric valve, and circulating water pump group, and controls each electric valve and circulating water pump group according to the signals collected by each pressure sensor and temperature sensor, so as to achieve constant temperature and constant pressure control of the circulating water system.

[0032] When the temperature difference between temperature sensors 1 and 2 is not lower than the first temperature difference setpoint and the pressure signal collected by pressure sensor 1 is not lower than the first pressure setpoint, i.e., when the temperature and pressure of the water supply network are within the normal range, electric valve 1 opens, and electric valves 2 and 4 close, and the first circulating water pump unit operates. At this time, the small circulation of the water supply network is not connected to the water supply network, and the first circulating water pump unit operates to provide water to the terminal. Furthermore, electric valve 3 can be either open or closed.

[0033] When the temperature difference between temperature sensors 1 and 2 is lower than the first temperature difference setpoint and / or the pressure signal collected by pressure sensor 1 is lower than the first pressure setpoint, i.e., when the temperature and / or pressure of the water supply network are not within the normal range, electric valves 1 and 3 close, and electric valves 2 and 4 open, and the first circulating water pump unit starts working. At this time, electric valve 2 connects the small circulation of the water supply network with the small circulation of the water supply network to form a large circulation, so as to maintain the temperature and pressure stability on the water supply side.

[0034] When the temperature difference between temperature sensors 3 and 4 is lower than the second temperature difference setpoint, electric valve 3 opens, while electric valves 2 and 4 close, and the second circulating water pump unit starts operating. At this time, the small circulation of the water supply network is not connected to the water usage network, the second circulating water pump unit operates and supplies hot water, and maintains a stable temperature on the water supply side.

[0035] When the pressure signal collected by pressure sensor 2 is lower than the second pressure set value, the second circulating water pump group and the makeup water pump group will operate. It should be understood that the second circulating water pump group can be turned on first. After the second circulating water pump group has been running for a period of time, if the pressure signal collected by pressure sensor 2 is still lower than the second pressure set value, the makeup water pump group will then be turned on to provide room temperature water.

[0036] It should be noted that when the circulating water pump set is working, two of the pumps can operate alternately or both pumps can operate simultaneously.

[0037] This application utilizes multiple electric valves to automatically switch between large and small circulation modes between the water supply network and the water pipe network. At the same time, it combines temperature and pressure sensors to monitor the system operating parameters in real time. The programmable controller coordinates the control of the circulating water pump and electric valves based on the temperature difference and pressure setpoint to achieve the joint regulation of constant temperature and constant pressure in the circulating water system.

[0038] To better understand the technical solution of this application, a specific example is provided below. The details listed in this example are mainly for ease of understanding and are not intended to limit the scope of protection of this application.

[0039] A constant temperature and pressure circulating water control system includes a water supply network and a water usage network, as well as the electrical control system required by the system. Specifically, such as... Figures 1 to 5As shown, the constant temperature and pressure circulating water control system includes a three-phase five-wire power supply, eight circuit breakers QF11~QF18, one fuse FU1, eight AC contactors KM1~KM8, six thermal relays KH1~KH6, one frequency converter VFD, one programmable logic controller (PLC), one analog module EM, one touch screen HMI, one switching power supply S, twelve intermediate relays KA1~KA12, one selector switch SA1, six indicator lights HL1~HL6, one audible and visual alarm HL7, eight pressure-sensitive resistors U1~U8, two pressure transmitters PT1~PT2, four temperature transmitters TT1~TT4, two overpressure relief valves 1~2, two automatic air vent valves 1~2, four electric valves 1~4 (or simply electric valves 1~4), and six water pumps 1~6.

[0040] like Figure 2 As shown, the output terminal of the first circuit breaker QF11 is connected to the first AC contactor KM1, the output terminal of the first AC contactor KM1 is connected to the first thermal relay KH1, and the output terminal of the first thermal relay KH1 is connected to water pump 1; the output terminal of the second circuit breaker QF12 is connected to the second AC contactor KM2, the output terminal of the second AC contactor KM2 is connected to the second thermal relay KH2, and the output terminal of the second thermal relay KH2 is connected to water pump 2; the output terminal of the third circuit breaker QF13 is connected to the third AC contactor KM3, the output terminal of the third AC contactor KM3 is connected to the third thermal relay KH3, and the output terminal of the third thermal relay KH3 is connected to water pump 3; the output terminal of the fourth circuit breaker QF14 is connected to the fourth AC contactor KM4, the output terminal of the fourth AC contactor KM4 is connected to the fourth thermal relay KH4, and the output terminal of the fourth thermal relay KH4 is connected to water pump 4. The output terminal of the fifth circuit breaker QF15 is connected to the fifth AC contactor KM5. The output terminal of the fifth AC contactor KM5 is connected to the fifth thermal relay KH5. The output terminal of the fifth thermal relay KH5 is connected to the water pump 5. The output terminal of the sixth circuit breaker QF16 is connected to the seventh AC contactor KM7. The output terminal of the seventh AC contactor KM7 is connected to the sixth thermal relay KH6. The output terminal of the sixth thermal relay KH6 is connected to the water pump 6. The output terminal of the seventh circuit breaker QF17 is connected to the frequency converter VFD. The output terminals of the frequency converter VFD are connected to the sixth AC contactor KM6 and the eighth AC contactor KM8 respectively. The output terminal of the sixth AC contactor KM6 is connected to the water pump 5. The output terminal of the eighth AC contactor KM8 is connected to the water pump 6. The output terminals of the eighth circuit breaker QF18 are connected to the power supply terminals of electric valves 1, 2, 3, and 4 respectively.

[0041] like Figure 3As shown, the live wire L3 and neutral wire N of the control circuit are connected to various devices in the secondary electrical control circuit. The output terminal of the eighth circuit breaker QF18 is connected to the common terminal of the normally open and normally open contacts of the first intermediate relay KA1. The other end of the normally open contact of the first intermediate relay KA1 is connected to the valve opening control circuit of electric valve 1. Its valve opening limit is connected to the control coil of the fifth intermediate relay KA5, and its valve closing limit is connected to the control coil of the sixth intermediate relay KA6. The control coils of the fifth intermediate relay KA5 and the sixth intermediate relay KA6 are connected to the neutral wire N of the control circuit. The output terminal of the eighth circuit breaker QF18 is connected to the common terminal of the normally open and normally open contacts of the second intermediate relay KA2. The other end of the normally open contact of the second intermediate relay KA2 is connected to the valve opening control circuit of electric valve 2. Its valve opening limit is connected to the control coil of the seventh intermediate relay KA7, and its valve closing limit is connected to the control coil of the eighth intermediate relay KA8. The control coils of the seventh intermediate relay KA7 and the eighth intermediate relay KA8 are connected to the control coil of the electric valve 2. The coil is connected to the neutral line N of the control circuit; the output terminal of the eighth circuit breaker QF18 is connected to the common terminal of the normally open and normally open contacts of the third intermediate relay KA3, and the other end of the normally open contact of the third intermediate relay is connected to the valve opening control circuit of the electric valve 3. Its valve opening limit is connected to the control coil of the ninth intermediate relay KA9, and its valve closing limit is connected to the control coil of the tenth intermediate relay KA10. The control coils of the ninth intermediate relay KA9 and the tenth intermediate relay KA10 are connected to the neutral line N of the control circuit; the output terminal of the eighth circuit breaker QF18 is connected to the common terminal of the normally open and normally open contacts of the fourth intermediate relay KA4, and the other end of the normally open contact of the fourth intermediate relay KA4 is connected to the valve opening control circuit of the electric valve 4. Its valve opening limit is connected to the control coil of the eleventh intermediate relay KA11, and its valve closing limit is connected to the control coil of the twelfth intermediate relay KA12. The control coils of the eleventh intermediate relay KA11 and the twelfth intermediate relay KA12 are connected to the neutral line N of the control circuit.

[0042] like Figure 4 and Figure 5As shown, the live wire L3 of the control circuit is connected to the input terminal of fuse FU1. The output terminal of fuse FU1 and the neutral wire N of the control circuit are respectively connected to the power supply terminals L1 and N of the programmable logic controller (PLC). The first indicator light HL1 and the live wire terminal of the switching power supply S are connected. The output terminal of the switching power supply S is connected to the touch screen HMI, the first pressure transmitter PT1 and the second pressure transmitter PT2, the first temperature transmitter TT1, the second temperature transmitter TT2, the third temperature transmitter TT3, and the fourth temperature transmitter TT4. The normally open contacts of the selector switch SA1, the first AC contactor KM1 to the eighth AC contactor KM8, the normally open contacts of the first thermal relay KH1 to the sixth thermal relay KH6, and the normally open contacts of the fifth intermediate relay KA5 to the twelfth intermediate relay KA12 are respectively connected to the first digital input terminal I0.0 to the twentieth digital input terminal I2.7, their common input terminals M to 2M, and the power supply terminal L+ of the PLC. The first to the second... The output terminals Q0.0~Q2.1 of the eighteen relays are respectively connected to the control coils of the first to eighth AC contactors KM1~KM8, the control coils of the first to fourth intermediate relays KA1~KA4, the second to sixth indicator lights HL2~HL6, and one end of the audible and visual alarm HL7. The two ends of the first to eighth varistor U1~U8 are respectively connected to the two ends of the control coils of the first to eighth AC contactors KM1~KM8. The other end of the control coils of the first to eighth AC contactors KM1~KM8, the control coils of the first to fourth intermediate relays KA1~KA4, the second to sixth indicator lights HL2~HL6, and the audible and visual alarm HL7 is connected to the neutral line N of the control circuit. The RJ45 communication interface of the programmable controller (PLC) is connected to the touch screen HMI. The Port1 communication interface of the PLC communicates with the frequency converter VFD in RS485 form. The Port2 communication interface of the PLC is an external communication interface in RS485 form.

[0043] When the system is in commissioning or emergency use mode, the water pumps, electric valves, and frequency converters can all be operated manually. The operating status, fault status, limit status, and sensor signals of each device are fed back to the electrical control system, which displays them on the touch screen. Based on the feedback information, the corresponding devices can be manually operated to ensure the system runs smoothly.

[0044] When the system is in normal use, the operating status, fault status, limit status, and sensor signals of each device are fed back to the electrical control system. The electrical control system then performs automatic control based on the detection data and system settings to ensure stable system operation. The specific control methods of the electrical control system are as follows.

[0045] When the temperature of the temperature sensors 1-2 before and after the water supply network user end is not lower than the temperature difference set value and the first pressure sensor is not lower than the pressure set value, the electric valve 1 is opened and the electric valves 3 and 4 are closed. The water supply network is a small circulation system and is not connected to the water supply network. The circulating water pump group 1 is started periodically. The pump 1 or the pump 2 is started alternately to ensure the temperature and pressure requirements of the water supply at the user end.

[0046] When the temperature of the front and rear temperature sensors 1-2 at the user end of the water supply network is lower than the temperature difference set value and / or the pressure detected by the first pressure sensor is lower than the user-side pressure set value, the electric valve 1 is closed and the electric valves 2 and 4 are opened, the water supply network is connected to the water supply network, the water supply network is in a large circulation system, and the circulating water pump group 1 is started periodically. The pump 1 or the pump 2 is started alternately to ensure the temperature and pressure requirements of the water at the user end.

[0047] When the temperature of the hot water supply and return water temperature sensors 3-4 is lower than the set temperature difference value, the electric valve 3 is opened. The water supply network is a small circulation system, and the circulating water pump group 2 is started periodically. The pump 3 or pump 4 is started and run alternately to maintain the stable output of the system on the water supply network side with less energy consumption.

[0048] To maintain stable pressure on the water supply network side, whether in a small or large circulation system, water pumps 5 and 6 are used to control water replenishment to ensure that the network pressure is not lower than the set value. Specifically, pressure sensor 2 detects the system pressure, and the frequency converter controls the speed of water pump 5 or water pump 6 to achieve constant pressure water replenishment. Before starting the water replenishment pump (water pump 5 or water pump 6), the hot water circulation pump (water pump 3 or water pump 4) should be started to ensure that the small circulation system on the water supply side is in dynamic pressure balance.

[0049] The steps for operating the control system of this invention are as follows: (a) First, close the circuit breakers QF11~QF18 and fuse FU1 in the control cabinet, and the system is in the power-on standby state.

[0050] (b) Manual / automatic mode can be selected by selecting switch SA1 to achieve manual or automatic control.

[0051] (c) When the system is in manual mode, electrical equipment can be controlled by the switches on the touch screen HMI. The main functions are the opening and closing control of four electric valves 1 to 4, the starting and stopping control of six water pumps 1 to 6, and the starting and stopping control of the frequency converter VFD.

[0052] (d) When the system is in automatic mode, the programmable controller will accurately control the frequency converter according to the parameters set on the touch screen HMI and the predetermined program, through communication, to complete the constant temperature and constant pressure control of the system.

[0053] (e) Regardless of whether the system is in manual or automatic mode, system parameters can be set on the touch screen HMI, mainly including the range of the pressure sensor, the range of the temperature sensor, the set values ​​of the system pressure and temperature on the water side, the set values ​​of the system pressure and temperature on the water supply side, and the PID parameters required for constant pressure water supply.

[0054] (f) The system monitors the status of the frequency converter in real time through RS485 communication. When an abnormality is detected, the system will stop the operation of the corresponding frequency converter in a timely manner through the control loop to avoid adverse consequences to the water pump and equipment system.

[0055] (g) The water supply network also includes a first overpressure relief valve (e.g., overpressure relief valve 1) and a first automatic air vent valve (e.g., automatic air vent valve 1) installed at a high position on the water supply side of the network. The system uses the overpressure relief valve 1 to provide overpressure relief protection on the water supply side, and uses the automatic air vent valve 1 to effectively and automatically discharge water vapor and other substances from the pipeline system.

[0056] (h) The water supply network also includes a second overpressure relief valve (e.g., overpressure relief valve 2) and a second automatic air release valve (e.g., automatic air release valve 2) installed at a high position on the water supply side. Similarly, the system uses the overpressure relief valve 2 to relieve overpressure on the water supply side and the automatic air release valve 2 to effectively and automatically release water vapor and other substances from the pipeline system, thereby effectively protecting the entire circulating water system.

[0057] As used in this article, the term "three-phase four-wire" generally includes three phase wires (A, B, C lines, U, V, W lines or L1, L2, L3) that provide three phase voltages, and a neutral wire (N line). There is no separate ground wire (PE line); instead, the neutral wire and ground wire share a single circuit. The incoming service line generally uses a single-phase three-wire system, including one of the three phase wires. The other two lines are essentially a single circuit shared by the neutral wire and ground wire.

[0058] The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this patent application, if reference is made to performing an action based on an element, it means performing the action at least based on that element, including two cases: performing the action only based on that element, and performing the action based on that element and other elements. Expressions such as "multiple," "repeatedly," and "various" include two, two times, two kinds, and more than two, more than two times, and more than two kinds.

[0059] The various technical features disclosed in the above-described invention, the various technical features disclosed in the following embodiments and examples, and the various technical features disclosed in the accompanying drawings can be freely combined to form various new technical solutions (all of which should be considered as having been recorded in this specification), unless such a combination of technical features is technically infeasible. For example, in one example, feature A+B+C is disclosed, and in another example, feature A+B+D+E is disclosed. Features C and D are equivalent technical means that serve the same function, and technically only one needs to be used; it is impossible to use both simultaneously. Feature E can be technically combined with feature C. Therefore, the solution A+B+C+D should not be considered as having been recorded because it is technically infeasible, while the solution A+B+C+E should be considered as having been recorded.

[0060] The term “coupled to” and its derivatives may be used in this document. “Coupled” can mean two or more elements in direct physical or electrical contact. However, “coupled” can also mean two or more elements in indirect contact with each other, but still cooperating or interacting with each other, and can mean one or more other elements coupled or connected between elements referred to as being coupled to each other.

[0061] All references to this specification are considered to be incorporated integrally into the disclosure of this application so that they can serve as the basis for modifications if necessary. Furthermore, it should be understood that the above descriptions are merely preferred embodiments of this specification and are not intended to limit the scope of protection of this specification. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of this specification should be included within the scope of protection of one or more embodiments of this specification.

[0062] In some cases, the actions or steps described in the claims can be performed in a different order than that shown in the embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

Claims

1. A constant temperature and pressure circulating water control system, characterized in that, It includes a water supply network, a water distribution network, and an electrical control system for controlling the water circulation of the water supply network and the water distribution network; The water supply network includes several user terminals, a first circulating water pump group, a first pressure sensor and a first temperature sensor located at the outlet of the first circulating water pump group, a second temperature sensor located downstream of the several user terminals, and a first electric valve. The water supply network includes a second circulating water pump set for supplying hot water, a third temperature sensor at the hot water supply point, a fourth temperature sensor at the hot water return point, and a third electric valve. A second electric valve and a fourth electric valve are respectively connected between the water supply network and the water usage network; The electrical control system is electrically connected to each pressure sensor, each temperature sensor, each electric valve, and each circulating water pump group, and controls each electric valve and each circulating water pump group based on the signals collected by each pressure sensor and each temperature sensor to achieve constant temperature and constant pressure control of the circulating water system, wherein: When the temperature difference between the first temperature sensor and the second temperature sensor is not lower than the first temperature difference setting value and the pressure signal collected by the first pressure sensor is not lower than the first pressure setting value, the first electric valve opens, the second electric valve and the fourth electric valve close, the first circulating water pump group works, and the water circulation of the water supply network is started to maintain the temperature and pressure stability of the user terminal. When the difference between the temperature signals collected by the first temperature sensor and the second temperature sensor is lower than the first temperature difference set value and / or the pressure signal collected by the first pressure sensor is lower than the first pressure set value, the first electric valve and the third electric valve are closed, the second electric valve and the fourth electric valve are opened, the first circulating water pump group and the second circulating water pump group are working, and the water circulation between the water supply network and the water supply network is started. When the temperature difference between the third temperature sensor and the fourth temperature sensor is lower than the second temperature difference set value, the third electric valve opens, the second electric valve and the fourth electric valve close, the second circulating water pump group starts working, and the water circulation of the water supply network is started to maintain the temperature stability of the water supply network.

2. The system as described in claim 1, characterized in that, The water supply network also includes: a water replenishment pump group located at the hot water return point for making water at room temperature, and a second pressure sensor located at the outlet of the water replenishment pump group; when the pressure signal collected by the second pressure sensor is lower than the second pressure set value, the second circulating water pump group and the water replenishment pump group work to maintain the pressure stability of the water supply network.

3. The system as described in claim 2, characterized in that, The first circulating water pump group consists of a first circulating water pump and a second circulating water pump connected in parallel; the second circulating water pump group consists of a third circulating water pump and a fourth circulating water pump connected in parallel; and the makeup water pump group consists of a fifth circulating water pump and a sixth circulating water pump connected in parallel.

4. The system as described in claim 3, characterized in that, The electrical control system also includes: first to eighth circuit breakers (QF11~QF18), first to eighth AC contactors (KM1~KM8), first to sixth thermal relays (KH1~KH6), and frequency converters (VFD). The output terminal of the first circuit breaker (QF11) is connected to the first AC contactor (KM1), the output terminal of the first AC contactor (KM1) is connected to the first thermal relay (KH1), and the output terminal of the first thermal relay (KH1) is connected to the first circulating water pump; the output terminal of the second circuit breaker (QF12) is connected to the second AC contactor (KM2), the output terminal of the second AC contactor (KM2) is connected to the second thermal relay (KH2), and the output terminal of the second thermal relay (KH2) is connected to the second circulating water pump; The output terminal of the third circuit breaker (QF13) is connected to the third AC contactor (KM3), the output terminal of the third AC contactor (KM3) is connected to the third thermal relay (KH3), and the output terminal of the third thermal relay (KH3) is connected to the third circulating water pump; the output terminal of the fourth circuit breaker (QF14) is connected to the fourth AC contactor (KM4), the output terminal of the fourth AC contactor (KM4) is connected to the fourth thermal relay (KH4), and the output terminal of the fourth thermal relay (KH4) is connected to the fourth circulating water pump; the... The output terminal of the fifth circuit breaker (QF15) is connected to the fifth AC contactor (KM5), the output terminal of the fifth AC contactor (KM5) is connected to the fifth thermal relay (KH5), and the output terminal of the fifth thermal relay (KH5) is connected to the fifth circulating water pump; the output terminal of the sixth circuit breaker (QF16) is connected to the seventh AC contactor (KM7), the output terminal of the seventh AC contactor (KM7) is connected to the sixth thermal relay (KH6), and the output terminal of the sixth thermal relay (KH6) is connected to the sixth circulating water pump; The output terminal of the seventh circuit breaker (QF17) is connected to the frequency converter (VFD). The output terminals of the frequency converter (VFD) are respectively connected to the sixth AC contactor (KM6) and the eighth AC contactor (KM8). The output terminal of the sixth AC contactor (KM6) is connected to the fifth circulating water pump, and the output terminal of the eighth AC contactor (KM8) is connected to the sixth circulating water pump. The output terminal of the eighth circuit breaker (QF18) is respectively connected to the power supply terminals of the first electric valve, the second electric valve, the third electric valve, and the fourth electric valve.

5. The system as described in claim 4, characterized in that, The electrical control system also includes: a fuse (FU1) and the first to twelfth intermediate relays (KA1~KA12). The incoming terminal of the eighth circuit breaker (QF18) is connected to the live wire (L3). The outgoing terminals of the eighth circuit breaker (QF18) are respectively connected to the common terminal of the normally open and normally open contacts of the first to fourth intermediate relays (KA1~KA4). The other end of the normally open contact of the first intermediate relay (KA1) is connected to the valve opening control circuit of the first electric valve, and its valve opening limit and valve closing limit are respectively connected to one end of the control coil of the fifth and sixth intermediate relays (KA5, KA6). The other end of the normally open contact of the second intermediate relay (KA2) is connected to the valve opening control circuit of the second electric valve, and its valve opening limit and valve closing limit are respectively connected to the seventh and eighth intermediate relays (KA7, KA8, KA9). One end of the control coil of the third intermediate relay (KA3) is connected to the valve opening control circuit of the third electric valve, and its valve opening limit and valve closing limit are respectively connected to the control coils of the ninth and tenth intermediate relays (KA9, KA10); the other end of the normally open contact of the fourth intermediate relay (KA4) is connected to the valve opening control circuit of the fourth electric valve, and its valve opening limit and valve closing limit are respectively connected to one end of the control coils of the eleventh and twelfth intermediate relays (KA11, KA12); the other end of the control coils of the fifth to twelfth intermediate relays (KA5~KA12) is connected to the neutral line (N) of the control circuit.

6. The system as described in claim 5, characterized in that, The electrical control system also includes: a programmable logic controller (PLC), an analog quantity module (EM), a touch screen (HMI), a selector switch (SA1), first and second pressure transmitters (PT1~PT2), and first to fourth temperature transmitters (TT1~TT4). The incoming terminal of fuse (FU1) is connected to the live wire (L3), and the outgoing terminal of fuse (FU1) is connected to the power supply terminal (L1) of programmable logic controller (PLC). The grounding terminal (N) of PLC is connected to the neutral wire (N). The first indicator light (HL1) and the live wire terminal of the switching power supply (S) are connected. The output terminal of the switching power supply (S) is connected to the touch screen (HMI), the first and second pressure transmitters (PT1~PT2), and the first to fourth temperature transmitters (TT1~TT4). The output terminals of the second pressure transmitter (PT1~PT2) and the first to fourth temperature transmitters (TT1~TT4) are connected to the analog module (EM). The normally open contacts of the selector switch (SA1), the first to eighth AC contactors (KM1~KM8), the first to sixth thermal relays (KH1~KH6), and the fifth to sixth thermal relays are connected to the normally open contacts of the second pressure transmitter (PT1~PT2) and the fourth thermal relays (TT1~TT4). The normally open contacts of the twelve intermediate relays (KA5~KA12) are connected to the first to twentieth digital input terminals (I0.0~I2.7) of the programmable logic controller (PLC); the output terminals (Q0.0~Q2.0) of the first to eleventh relays of the PLC are connected to the control coils of the first to eighth AC contactors (KM1~KM8) and the control coils of the first to fourth intermediate relays (KA1~KA4), respectively; the other end of the control coils of the first to eighth AC contactors (KM1~KM8) and the control coils of the first to fourth intermediate relays (KA1~KA4) are connected to the neutral wire (N); the RJ45 communication interface of the PLC is connected to the touch screen (HMI), and the Port1 communication interface of the PLC communicates with the frequency converter (VFD).

7. The system as described in claim 6, characterized in that, The electrical control system further includes: first to eighth varistors (U1~U8), the two ends of which are respectively connected to the two ends of the control coils of the first to eighth AC contactors (KM1~KM8).

8. The system as described in claim 6, characterized in that, The electrical control system also includes: first to sixth indicator lights (HL1~HL6) and an audible and visual alarm (HL7). The output terminals (Q1.4~Q2.1) of the twelfth to eighteenth relays of the programmable controller (PLC) are respectively connected to the second to sixth indicator lights (HL2~HL6) and the audible and visual alarm (HL7). The other end of the second to sixth indicator lights (HL2~HL6) and the audible and visual alarm (HL7) is connected to the neutral wire (N).

9. The system as described in claim 1, characterized in that, The water supply network also includes a first overpressure relief valve and a first automatic air release valve installed at a high position on the water supply side of the network.

10. The system as claimed in claim 1, characterized in that, The water supply network also includes a second overpressure relief valve and a second automatic air release valve installed at a high position on the water supply side of the network.

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