Wastewater pool conveying control system of MVR (Mechanical Vapor Recompression) recovery device

Abstract

The utility model provides a wastewater pool conveying control system of an MVR (Mechanical Vapor Recompression) recovery device. The wastewater pool conveying control system comprises a wastewater pool, a water outlet pipe, a water pump, a central control upper computer, a PLC (Programmable Logic Controller) and a control cabinet, the upper water outlet pipe, the water pump and the lower water outlet pipe are sequentially connected from top to bottom, the water pump is arranged above the supporting table and provided with a water outlet pipe pressure transmitter, the lower water outlet pipe extends downwards to the bottom of the wastewater pool, and a liquid level pressure transmitter is arranged on the supporting table; the PLC is provided with an input port and an output port and is connected with a first signal line, a second signal line, a bus cable, a control cable and a connecting cable; the water pump comprises a water pump power line and a water pump control loop, the water pump is connected with the control cabinet through the water pump power line and connected with an output port of the PLC through the water pump control loop, and the PLC is connected with the control cabinet and the water pump in parallel. According to the utility model, the problem that the original control system does not have water shortage and water plugging protection is solved, and the use difficulty of the system is simplified.

Description

Technical Field

[0001] This utility model belongs to the field of chemical equipment and relates to a wastewater tank conveying control system for an MVR recovery device. Background Technology

[0002] Existing MVR (Multi-Volume Recycling) devices are high-efficiency, energy-saving evaporators. Their principle involves using a high-efficiency steam compressor to compress the secondary steam generated during evaporation, converting electrical energy into heat energy and increasing the enthalpy of the secondary steam. This increased heat energy is then pumped into the evaporation chamber for heating, achieving the recycling of the existing heat energy of the secondary steam. This eliminates the need for external fresh steam, relying on the evaporator's self-circulation to achieve the purpose of evaporation and concentration of extractable water from slices. Existing MVR devices control system temperature, pressure, and motor speed through PLCs, microcontrollers, and configuration software to maintain system evaporation balance. Wastewater generated during production is temporarily stored in a wastewater tank. When the wastewater level reaches the high level required by the process, a water pump is activated to transport the wastewater to a wastewater treatment plant for environmental treatment. When the wastewater level reaches the low level required by the process, the water pump stops operating. The entire process is continuous and cannot be stopped arbitrarily; any shutdown would result in significant economic losses.

[0003] The existing wastewater transport control system is a separate control cabinet that is not connected to the central control room. Operators conduct regular inspections, but cannot detect equipment abnormalities in a timely manner. The original control system used a float level switch to control the start and stop of the water pump, and lacked protection against water shortage and blockage. Due to the high temperature of the wastewater tank and the fact that the float level switch operated while submerged in the wastewater, the operating environment was harsh. The float level switch used mechanical contacts, which had a limited lifespan due to the number of contact breaks, and frequently experienced faulty contact. Once a fault occurred, firstly, the water pump could not stop working when the liquid level was lower than the set value, resulting in waterless operation. Secondly, if the water pump inlet was blocked by foreign objects, water could not enter the pump, also resulting in waterless operation. The pump would run for a long time without water, and the temperature would rise rapidly due to the lack of water cooling, leading to the burnout of pump components. Thirdly, if the outlet pipe was blocked, the pump would continue to run, resulting in ineffective operation, wasted electricity, and potential motor overload, shortening the lifespan of the pump and motor. Fourthly, if the liquid level was higher than the set value, the pump would not run, resulting in a full tank of wastewater. Only a submersible pump could be used temporarily to pump out the wastewater. If the wastewater could not be discharged in time, it would affect the operation of the entire MVR unit, causing significant economic losses. Summary of the Invention

[0004] The technical problem to be solved by this utility model is to provide a wastewater tank conveying control system for an MVR recycling device, which adds a water pump outlet pipeline pressure transmitter and a liquid level pressure transmitter, and adopts a PLC controller to solve the problem that the original control system does not have water shortage and water blockage protection, reduces the water pump malfunction caused by the unreliability of the original liquid level switch, and simplifies the difficulty of system installation, debugging and use.

[0005] This utility model is implemented as follows:

[0006] This utility model provides a wastewater tank conveying control system for an MVR recycling device, including: a wastewater tank, an outlet pipe, a water pump, a central control host computer, a PLC controller, and a control cabinet;

[0007] The wastewater tank includes a support platform and a liquid level and pressure transmitter, and the outlet pipe includes an upper outlet pipe, a lower outlet pipe and an outlet pipe pressure transmitter.

[0008] The upper water outlet pipe, water pump, and lower water outlet pipe are connected in sequence from top to bottom. The water pump is located above the support platform. The lower water outlet pipe extends downward to the bottom of the wastewater tank. A water outlet pipe pressure transmitter is installed on the upper water outlet pipe to detect the pressure inside the water outlet pipe. A liquid level pressure transmitter is installed on the support platform to detect the pressure at the bottom of the wastewater tank.

[0009] The PLC controller is connected to a first signal line, a second signal line, a bus cable, and a control cable;

[0010] The PLC controller is equipped with an analog input port, a digital input port, and a digital output port. The liquid level and pressure transmitter is connected to the analog input port through the first signal line, and the water outlet pipe pressure transmitter is connected to the analog input port through the second signal line. The central control host computer is connected to the PLC controller through the bus cable, and the control cabinet is connected to the PLC controller through the control cable.

[0011] The water pump includes a water pump power line, and the control cabinet includes a water pump control circuit. The water pump is connected to the control cabinet through the water pump power line, and the water pump control circuit is connected to the digital output port of the PLC controller. The PLC controller and the control cabinet are connected in parallel.

[0012] Furthermore, the control cabinet also includes a water pump motor thermal protection relay, which is located inside the control cabinet; the normally closed contact of the water pump motor thermal protection relay is connected to the digital input port of the PLC controller.

[0013] Furthermore, it also includes a first audible and visual alarm and a second audible and visual alarm; the central control host computer is electrically connected to the first audible and visual alarm; and the control cabinet is electrically connected to the second audible and visual alarm.

[0014] The advantages of this utility model are:

[0015] This utility model provides a wastewater conveying control system for an MVR recycling device. A pressure transmitter at the pump outlet detects the internal pressure of the pipeline, and a pressure transmitter detects the pressure at the bottom of the tank to measure the liquid level. A PLC controller is used, with synchronous signal and control communication between the PLC controller and the central control computer, as well as between the PLC controller and the visual touchscreen. During liquid conveying, the system automatically shuts down and alarms when the outlet pipeline pressure is too low or too high. The liquid level exhibits high stability and reliability, and the pressure transmitter triggers an audible and visual alarm when the liquid level exceeds the limit. The liquid conveying process includes multi-point automatic and manual control, as well as audible and visual alarms for faults.

[0016] To address the two major issues of reliable liquid level control and protection against water shortage and blockage during water pump operation, this invention employs a highly reliable, accurate, and environmentally resistant pressure transmitter installed at the bottom of the wastewater tank to detect the bottom pressure. Based on the direct proportionality between liquid level and bottom pressure, the pressure signal is connected to a PLC controller. A pressure transmitter is also installed on the water pump outlet pipe (near the pump body). Considering the characteristics of the water pump outlet pipe—high pressure during normal operation, low or no pressure during water shortage, and pressure significantly exceeding normal operating pressure during blockage—the outlet pipe pressure signal is connected to the PLC controller. Simultaneously, the normally closed contact of the water pump motor thermal protection relay is connected to the PLC controller. The PLC controller, based on changes in the input liquid level and outlet pipe pressure signals, uses a program to determine the pump's operation and controls its automatic operation via a contactor in the field control box. The pump automatically stops when the water level reaches a high setpoint and when it reaches a low setpoint. If the water level exceeds a preset high-high or low-low level, corresponding audible and visual alarm signals are simultaneously issued on the field control cabinet and the central control computer. If the water pump inlet is blocked or the outlet pipe is clogged, the pump will automatically stop running, and corresponding audible and visual alarm signals will be issued simultaneously on the local control cabinet and the central control computer, reminding operators to check the cause of the fault on-site. Operators can adjust parameters and start / stop the pump on the local visual touchscreen or on the central control computer. An audible and visual alarm will also be issued when the motor overloads and thermally protects against shutdown. Due to technological advancements, modern pressure transmitters offer very high accuracy, reliability, and resistance to harsh environments. Furthermore, the absence of mechanical contacts in pressure transmitters fundamentally solves the drawbacks of float level switches, such as limited lifespan due to the number of mechanical contacts and their vulnerability to harsh environments, leading to unreliable system control. The use of a PLC controller facilitates synchronization of signals and control with the central control computer, simplifies wiring and installation, and enhances reliability. Operation is more intuitive, simple, and convenient, allowing for more timely monitoring of equipment operation and providing more time for troubleshooting, thus improving equipment maintenance efficiency and ensuring normal equipment operation. Attached Figure Description

[0017] The present invention will now be further described with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of the structure of the system of this utility model. Detailed Implementation

[0019] This utility model provides a wastewater tank conveying control system for an MVR recycling device, which solves the problem of the original control system lacking water shortage and blockage protection, reduces pump malfunctions caused by unreliable level switches, and simplifies the difficulty of system installation, debugging, and use.

[0020] Example 1

[0021] This embodiment provides a wastewater transport control system for an MVR recycling device, such as... Figure 1 As shown, it includes: wastewater tank 1, water outlet pipe 2, water pump 3, central control host computer 4, PLC controller 5, visual touch screen 6 and control cabinet 7;

[0022] The control system of the central control host computer 4 includes a wastewater conveying control system configuration. After inputting the program on the visual touch screen 6, the system configuration can be performed.

[0023] Both the control cabinet 7 and the PLC controller 5 are used to control the water pump 3;

[0024] The wastewater tank 1 includes a support platform 101 and a liquid level and pressure transmitter 102, and the outlet pipe 2 includes an upper outlet pipe 201, a lower outlet pipe 202 and an outlet pipe pressure transmitter 203.

[0025] The upper outlet pipe 201, water pump 3, and lower outlet pipe 202 are connected sequentially from top to bottom. The water pump 3 is located above the support platform 101. The lower outlet pipe 202 extends downward to the bottom of the wastewater tank 1. An outlet pipe pressure transmitter 203 is installed on the upper outlet pipe 201 to detect the pressure inside the outlet pipe 202. A liquid level pressure transmitter 102 is installed on the support platform 101 to detect the pressure at the bottom of the wastewater tank 1.

[0026] The outlet pipe pressure transmitter 203 and the liquid level pressure transmitter 102 can automatically stop and protect themselves if the detected pressure is too low or too high, and trigger the first audible and visual alarm 401 and the second audible and visual alarm 701.

[0027] The PLC controller 5 is connected to a first signal line 501, a second signal line 502, a bus cable 503, a control cable 504, and a connecting cable 505.

[0028] The bus cable 503 uses a dedicated shielded cable and a dedicated plug;

[0029] The PLC controller 5 is equipped with an analog input port 506, a digital output port 507, and a digital input port 508.

[0030] The analog input port 506, digital output port 507, and digital input port 508 are preset by the program of the PLC controller 5.

[0031] The liquid level and pressure transmitter 102 is connected to the analog input port 506 of the PLC controller 5 via the first signal line 501; the outlet water pipe pressure transmitter 203 is connected to the analog input port 506 of the PLC controller 5 via the second signal line 502; the central control host computer 4 is connected to the PLC controller 5 via the bus cable 503; the visual touch screen 6 is connected to the PLC controller 5 via the connecting cable 505; and the control cabinet 7 is connected to the PLC controller 5 via the control cable 504.

[0032] The water pump 3 includes a water pump power line 301, and the control cabinet 7 includes a water pump control circuit 702.

[0033] The water pump 3 is connected to the control cabinet 7 via the water pump power line 301, and the water pump control circuit 702 is connected to the digital output port 507 of the PLC controller 5.

[0034] The control cabinet 7 also includes a water pump motor thermal protection relay 8, which is used to prevent the water pump motor from operating under overload conditions; the water pump motor thermal protection relay 8 is located inside the control cabinet 7; the normally closed contact of the water pump thermal protection relay 8 is connected to the digital input port 508 of the PLC controller 5.

[0035] The PLC controller 5 and the control cabinet 7 are connected in parallel.

[0036] Both the PLC controller 5 and the control cabinet 7 have the ability to independently control the operation and shutdown of the water pump 3;

[0037] In this embodiment, preferably, the system further includes a first audible and visual alarm 401 and a second audible and visual alarm 701; the central control host computer 4 is electrically connected to the first audible and visual alarm 401, and the control cabinet 7 is electrically connected to the second audible and visual alarm 701; when the water level exceeds the preset high-high level or low-low level, the first audible and visual alarm 401 and the second audible and visual alarm 701 simultaneously issue corresponding audible and visual alarm signals on the field control cabinet 7 and the central control host computer 4.

[0038] When in use, first turn off the main power supply of control cabinet 7, install pressure transmitter 203 on water outlet pipe 2, and then install liquid level pressure transmitter 102 in wastewater tank 1.

[0039] The first signal line 501 and the second signal line 502 of the two pressure transmitters to the PLC controller 5 are two-wire shielded cables to improve anti-interference capability.

[0040] One end of the PLC controller 5 is connected to two pressure transmitters, and the other end is connected to the analog input port 506 preset by the PLC controller program.

[0041] Then, the digital output port 507 preset by the PLC program is connected in parallel with the water pump control circuit 702 of the control cabinet 7, so that both the control cabinet 7 and the PLC controller 5 have the ability to independently control the operation and stop of the water pump 3.

[0042] Connect the normally closed contact of the water pump motor thermal protection relay 8 to the PLC controller 5 so that the PLC controller 5 can determine the working status of the motor based on the opening and closing of the contact.

[0043] The bus cable 503 is laid between the PLC controller 5 and the central control host computer 4. The bus cable 503 uses a special shielded cable and a special plug.

[0044] The PLC controller 5 and the visual touch screen 6 are connected using a dedicated connection cable 505;

[0045] The water pump power line 301 utilizes the existing wiring in the prior technology before the improvement;

[0046] Power on PLC controller 5, input the correct programmed program, check whether the communication between PLC controller 5 and the central control host computer 4 is normal, whether the communication with the visual touch screen 6 is normal, and whether the communication with the two pressure transmitters is normal, and set the pressure transmitter range.

[0047] The control system of the central control computer 4 includes the configuration of the wastewater conveying control system. The operator can perform system configuration by inputting program through the visual touch screen 6.

[0048] Disconnect the circuit breaker of the water pump control circuit 702, turn on the main power supply of control cabinet 7, and turn on the water pump control circuit 702. Test whether the water pump control circuit 702 is normal from control cabinet 7, visual touch screen 6, and central control host computer 4 respectively. After confirming that it is normal, use a signal generator to simulate the given operating parameters and observe whether the water pump contactor works normally. If it is normal, the control circuit debugging is over.

[0049] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0050] The above embodiments and figures are not intended to limit the product form and style of this utility model. Any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of this utility model.

Claims

1. A wastewater conveying control system for an MVR recycling device, characterized in that, include: Wastewater tank, effluent pipe, water pump, central control computer, PLC controller and control cabinet; The wastewater tank includes a support platform and a liquid level and pressure transmitter. The outlet pipe includes an upper outlet pipe, a lower outlet pipe, and an outlet pipe pressure transmitter. The upper outlet pipe, water pump, and lower outlet pipe are connected sequentially from top to bottom. The water pump is located above the support platform. The lower outlet pipe extends downward to the bottom of the wastewater tank. An outlet pipe pressure transmitter is installed on the upper outlet pipe to detect the pressure inside the outlet pipe. A liquid level and pressure transmitter is installed on the support platform to detect the pressure at the bottom of the wastewater tank. The PLC controller is connected to a first signal line, a second signal line, a bus cable, and a control cable; The PLC controller is equipped with an analog input port, a digital input port, and a digital output port. The liquid level and pressure transmitter is connected to the analog input port through the first signal line, and the water outlet pipe pressure transmitter is connected to the analog input port through the second signal line. The central control host computer is connected to the PLC controller through the bus cable, and the control cabinet is connected to the PLC controller through the control cable. The water pump includes a water pump power line, and the control cabinet includes a water pump control circuit. The water pump is connected to the control cabinet through the water pump power line and connected to the digital output port of the PLC controller through the water pump control circuit. The PLC controller, the control cabinet, and the water pump are connected in parallel.

2. The wastewater conveying control system for an MVR recycling device according to claim 1, characterized in that, The control cabinet also includes a water pump motor thermal protection relay, which is located inside the control cabinet; the normally closed contact of the water pump motor thermal protection relay is connected to the digital input port of the PLC controller.

3. The wastewater conveying control system for an MVR recycling device according to claim 1, characterized in that, It also includes a first audible and visual alarm and a second audible and visual alarm; the central control host computer is electrically connected to the first audible and visual alarm; the control cabinet is electrically connected to the second audible and visual alarm.

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