Heat pump low temperature evaporation system

Abstract

The utility model relates to a kind of heat pump low-temperature evaporation systems, including heat pump circulation system, it includes compressor, first heat exchange pipe, condenser, expansion valve and evaporator;Low-temperature vacuum evaporator, it includes low-temperature vacuum tank, multiple feed nozzles, circulating pipe and scraper device;Condensate tank, the condensate tank is connected with evaporator tank body by condensing water pipe, water injector is set on the condensing water pipe, vacuumizing low-temperature vacuum tank and evaporator tank body by water injector.Compared with the condition that the conventional single-stage condensing heat energy utilization rate is low, the utility model heat pump low-temperature evaporation system uses ladder heat recovery design, condensing heat is used in stages, primary water is heated, secondary evaporator temperature is maintained, COP is improved by more than 20%.

Description

Technical Field

[0001] This utility model relates to the field of environmental protection technology, specifically to a heat pump low-temperature evaporation system. Background Technology

[0002] Currently, saline wastewater treatment technologies mainly include multi-effect evaporation (MEE), mechanical vapor recompression (MVR), and low-temperature heat pump evaporation. Among these, low-temperature heat pump evaporation has gradually gained attention due to its advantages such as low energy consumption, low operating temperature, and compact equipment. Both MEE and MVR require steam. In recent years, low-temperature heat pump evaporation has been commonly used to treat saline wastewater for which there is no on-site steam and which has high heat sensitivity requirements. However, existing low-temperature heat pump evaporation systems often suffer from the following problems during operation:

[0003] 1. Low heat recovery efficiency: Condensation heat is not fully utilized, resulting in a low system coefficient of performance (COP);

[0004] 2. Evaporator is prone to scaling: During the low-temperature evaporation process of high-salt wastewater, local supersaturation leads to crystal deposition, which affects heat transfer efficiency;

[0005] 3. The control system lacks dynamic control over evaporation temperature, vacuum level, and concentration ratio, making it difficult to adapt to fluctuations in influent water quality;

[0006] 4. Crystallized salts are mostly wet salts with high moisture content, requiring additional drying treatment, which increases the cost of subsequent processing.

[0007] To address the aforementioned issues, a heat pump low-temperature evaporation system integrating cascade heat recovery, intelligent temperature control, and anti-fouling design is proposed for development. Utility Model Content

[0008] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a heat pump low-temperature evaporation system to solve the technical problems of low heat recovery efficiency, easy scaling, and high cost of crystallization salt treatment in existing low-temperature evaporation systems.

[0009] The technical solution adopted by this utility model to solve its technical problem is:

[0010] A heat pump low-temperature evaporation system is provided, including...

[0011] A heat pump cycle system includes a compressor, a first heat exchange tube, a condenser, an expansion valve, and an evaporator. The condenser contains a second heat exchange tube, and the evaporator contains a third heat exchange tube.

[0012] A low-temperature vacuum evaporator includes a low-temperature vacuum tank, multiple feed nozzles, a circulation pipe, and a scraper device. Each feed nozzle is distributed inside the low-temperature vacuum tank and connected to a wastewater inlet pipe. The circulation pipe connects the wastewater inlet pipe and the concentrate outlet pipe. The first heat exchange tube is installed inside the low-temperature vacuum tank and is used to provide the evaporation temperature. The condenser is installed on the wastewater inlet pipe and is used to heat the raw water. The top of the low-temperature vacuum tank is connected to the top pipe of the evaporator tank.

[0013] A condensate tank is connected to the evaporator tank via a condensate pipe. A water jet is installed on the condensate pipe to evacuate the low-temperature vacuum tank and the evaporator tank. The water inlet of the water jet is connected to a jet pump, which is connected to the condensate tank. The outlet of the condensate tank is connected to a filter via a pipe.

[0014] Furthermore, it also includes a crystallized salt collection system, which includes a centrifugal dehydrator, a concentrate drain pipe, and a return pipe. The concentrate drain pipe is connected to a low-temperature vacuum tank and a centrifugal dehydrator, and the return pipe is connected to a centrifugal dehydrator and a wastewater storage tank.

[0015] Furthermore, a fourth heat exchange tube is installed inside the condensate tank, and the fourth heat exchange tube is connected to the cooling tower.

[0016] Furthermore, a flow switch is installed on the circulation pipe.

[0017] Furthermore, an electric heater is installed on the pipeline between the condenser and the expansion valve.

[0018] Furthermore, the filter is an activated carbon filter or a reverse osmosis filter.

[0019] The beneficial effects of this utility model are:

[0020] This utility model relates to a heat pump low-temperature evaporation system. The low-temperature vacuum evaporator employs a single-effect forced circulation to evaporate saline wastewater. The heat for evaporation in the low-temperature vacuum evaporator is provided by a heat pump circulation system. This system heats the wastewater entering the evaporator in stages: firstly, the raw water in the wastewater inlet pipe is preheated by a condenser; then, the wastewater is further heated in the low-temperature vacuum tank through a first heat exchange tube to maintain evaporation and keep the evaporator in thermal balance. Simultaneously, the vacuum level in both the low-temperature vacuum tank and the evaporator tank is maintained by a water jet pumping out condensate from the evaporator tank.

[0021] Compared to the low heat energy utilization rate of conventional single-stage condensation, this practical heat pump low-temperature evaporation system adopts a cascade heat recovery design, which utilizes condensation heat in stages. The first stage heats the raw water, and the second stage maintains the evaporator temperature, increasing the COP by more than 20%.

[0022] To address the issue of traditional evaporators being prone to scaling and requiring frequent shutdowns for cleaning, an adjustable scraper is installed inside the evaporator to remove surface crystals in real time, extending the cleaning cycle to more than 30 days.

[0023] The crystallized salt collection system enables automatic collection and preliminary dehydration of crystallized salt (moisture content ≤15%).

[0024] The heat pump low-temperature evaporation system of this utility model has the technical advantages of low energy consumption, stable operation and high degree of automation: the system COP≥4.5, energy consumption per ton of water≤35kWh; anti-scaling design + intelligent control, adapting to fluctuations in influent water; one-button start, remote monitoring, and easy maintenance. Attached Figure Description

[0025] The present invention will be further described below with reference to the accompanying drawings.

[0026] Figure 1 This is a schematic diagram of the heat pump low-temperature evaporation system of this utility model;

[0027] Figure 2 This is a schematic diagram of a heat pump cycle system;

[0028] Among them, 1. Low temperature vacuum evaporator, 11. Feed nozzle, 12. Circulation pipe, 13. Scraper device;

[0029] 2. Heat pump circulation system, 21. Compressor, 22. First heat exchange tube, 23. Condenser, 24. Expansion valve, 25. Evaporator, 251. Third heat exchange tube, 26. Electric heater;

[0030] 3. Condensate tank; 31. Fourth heat exchange tube; 32. Water jet; 33. Jet pump; 34. Cooling tower; 35. Filter.

[0031] 4. Centrifugal dehydrator; 41. Concentrate drain pipe; 42. Reflux pipe;

[0032] 5. Wastewater storage tank; 51. Transfer pump; 52. Feed solenoid valve; 53. Online salinity meter; 54. Feed temperature sensor.

[0033] 61. Evaporation temperature sensor; 62. Evaporation chamber vacuum transmitter; 63. Evaporation chamber dual-flange differential pressure transmitter; 64. Frequency converter; 65. Forced circulation pump; 66. Flow sensor; 67. Pressure sensor. Detailed Implementation

[0034] To further illustrate the technical means and effects adopted by this utility model in order to achieve the intended utility model purpose, the following detailed description of the specific implementation methods, structure, features and effects of this utility model is provided in conjunction with the accompanying drawings and preferred embodiments.

[0035] This application provides a heat pump low-temperature evaporation system, which will be described in detail below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments of this application. Furthermore, in the following embodiments, the descriptions of each embodiment have their own emphasis; parts not described in detail in a certain embodiment can be referred to in the relevant descriptions of other embodiments.

[0036] To address the technical problems of low heat recovery efficiency, easy scaling, and high cost of crystallizing salt treatment in existing low-temperature evaporation systems, an embodiment of this application provides a heat pump low-temperature evaporation system. This is described in detail below.

[0037] like Figure 1 As shown, a heat pump low-temperature evaporation system includes a heat pump circulation system 2, a low-temperature vacuum evaporator 1, a condensate tank 3, and a crystallization salt collection system.

[0038] like Figure 2 As shown, the heat pump cycle system 2 includes a compressor 21, a first heat exchange tube 22, a condenser 23, an expansion valve 24, and an evaporator 25. The condenser 23 is provided with a second heat exchange tube, and the evaporator 25 is provided with a third heat exchange tube 251.

[0039] The compressor 21, the first heat exchange tube 22, the condenser 23, the evaporator 25, the expansion valve 24 and the evaporator 25 are connected by a medium pipeline to form a circulation pipe 12. The medium pipeline is filled with an environmentally friendly thermal medium (such as one or more of R134a, R410a, R452b, R454b, etc.).

[0040] Specifically, an electric heater 26 is installed on the pipeline between the condenser 23 and the expansion valve 24. The electric heater 26 has a power of 10kW and is put into use during start-up or load fluctuations, and is normally turned off.

[0041] like Figure 1 As shown, the low-temperature vacuum evaporator 1 includes a low-temperature vacuum tank, multiple feed nozzles 11, a circulation pipe 12, and a scraper device 13. Each feed nozzle 11 is distributed inside the low-temperature vacuum tank and connected to a wastewater inlet pipe. The circulation pipe 12 connects the wastewater inlet pipe and the concentrate outlet pipe. The first heat exchange tube 22 is installed inside the low-temperature vacuum tank and is used to provide the evaporation temperature. The condenser 23 is installed on the wastewater inlet pipe and is used to heat the raw water. The top of the low-temperature vacuum tank is connected to the top pipe of the evaporator tank.

[0042] A condensate tank 3 is connected to the evaporator tank via a condensate pipe. A water jet 32 ​​is installed on the condensate pipe to evacuate the low-temperature vacuum tank and the evaporator tank. The water inlet of the water jet 32 ​​is connected to a jet pump 33, which is connected to the condensate tank 3. The outlet of the condensate tank 3 is connected to a filter 35 via a pipe.

[0043] The crystallized salt collection system includes a centrifugal dehydrator 4, a concentrate drain pipe 41, and a return pipe 42. The concentrate drain pipe 41 is connected to a low-temperature vacuum tank and the centrifugal dehydrator 4, and the return pipe 42 is connected to the centrifugal dehydrator 4 and the wastewater storage tank 5.

[0044] The jet pump 33 draws out the condensate in the evaporator tank, creating a vacuum between the low-temperature vacuum tank and the evaporator tank.

[0045] Specifically, as an optional implementation in this embodiment, a fourth heat exchange tube 31 is provided in the condensate tank 3, and the fourth heat exchange tube 31 is connected to the cooling tower 34.

[0046] In this embodiment, a flow switch is installed on the circulation pipe 12. When the flow switch is turned on, the wastewater in the low-temperature vacuum tank is circulated into the wastewater inlet pipe, causing the wastewater to circulate and evaporate.

[0047] In this embodiment, the filter 35 is an activated carbon filter or a reverse osmosis filter. The condensate, after being filtered by filter 35, is reused in the upstream cleaning or cooling system.

[0048] In this embodiment, the heat exchange tube is a coil.

[0049] like Figure 2 As shown, in the heat pump cycle system 2, the temperature of the heat medium in the first heat exchange tube 22 is about 65°C, providing a heat source for the low-temperature vacuum evaporator 1; the temperature of the heat medium in the third heat exchange tube 251 is about 40°C, and it exchanges heat with the secondary steam and absorbs the heat of the secondary steam, resulting in an effective temperature rise of 25°C.

[0050] During operation, compressor 21 pressurizes the high-temperature, high-pressure heat medium and sends it to the first heat exchange tube 22. The first heat exchange tube 22 provides evaporation heat in the low-temperature vacuum tank. After depressurization and cooling, the heat medium is sent to condenser 23, where it exchanges heat with the raw water passing through condenser 23. After heat exchange, the raw water is heated and sent to the low-temperature vacuum tank. The heat medium output from condenser 23 passes through expansion valve 24, where its temperature and pressure are further reduced. It then enters evaporator 25, exchanges heat with third heat exchange tube 251, and is finally supplied to compressor 21, repeating the cycle.

[0051] The wastewater inlet pipe between the wastewater storage tank 5 and the low-temperature vacuum evaporator 1 is equipped with a transfer pump 51, a feed solenoid valve 52, an online salinity meter 53, and a feed temperature sensor 54. The low-temperature vacuum evaporator 1 is equipped with an evaporation chamber double flange differential pressure transmitter 63, an evaporation chamber vacuum transmitter 62, and an evaporation temperature sensor 61. The concentrate discharge pipe 41 is equipped with a forced circulation pump 65.

[0052] When the low-temperature vacuum evaporator 1 is in operation, the salt crystals on the inner wall of the low-temperature vacuum tank can be scraped off by the scraper device 13. The scraper device 13 includes a scraper and a drive motor. The drive motor drives the scraper to rotate inside the tank to achieve scraping.

[0053] The low-temperature vacuum evaporator has a heat exchange area of ​​approximately 5 m² and is made of Ti or 316L material.

[0054] The forced circulation pump 65 has a flow rate of not less than 30 m3 / h and a head of about 25 m. The forced circulation pump 65 is connected to the frequency converter 64, and the frequency converter 64 adjusts the working frequency of the forced circulation pump 65, with a specification of 0-50 Hz.

[0055] Evaporation temperature sensor 61, measuring range 40-80℃;

[0056] The evaporation chamber dual-flange differential pressure transmitter 63 controls the liquid level, with a range of 0-2m;

[0057] Evaporation chamber vacuum transmitter, 62 range -100-0 kPa;

[0058] A flow sensor 66 is installed on the condensate pipe, with a flow rate of 660-3 m³ / h.

[0059] The water jet 32 ​​is connected to a pressure sensor 67, which is used to monitor the online pressure of the jet.

[0060] When the crystallized salt collection system is in operation, the concentrated water discharged from the low-temperature vacuum tank enters the centrifugal dehydrator 4. The flow rate of the concentrated liquid entering the centrifugal dehydrator 4 is controlled by the concentrated liquid regulating valve, and the flow rate is controlled to be about 0.5 m3 / h. The reflux control valve controls the return of the concentrated liquid from the centrifugal dehydrator 4 to the wastewater storage tank 5. The concentrated liquid online conductivity meter detects the concentrated water in the concentrated water discharge pipe 41, with a range of 0-300 mS / cm.

[0061] The heat pump low-temperature evaporation system of this utility model is equipped with a PLC controller. Based on parameters such as the online salinity meter 53 of the inlet water, the evaporation temperature sensor 61, and the differential pressure transmitter 63 of the double flange of the evaporation chamber, the evaporation temperature (45~60℃), vacuum degree (-85~-90kPa) and circulation rate of the low-temperature vacuum evaporator 1 are dynamically adjusted. It adopts a 4-2 Siemens PLC + touch screen, model S7-1700.

[0062] The PLC controller connects to the forced circulation pump 65, the frequency converter 64, the online salinity meter 53, and the evaporation chamber dual-flange differential pressure transmitter 63 to control the evaporation circulation rate.

[0063] The PLC controller connects to the electric heater 26, the inverter of the compressor 21, the expansion valve 24, the evaporation temperature sensor 61, and the feed temperature sensor 54 to control the evaporation temperature at 46℃.

[0064] The PLC controller connects to the water jet injector 32, the jet pump 33, the pressure sensor 67, and the evaporation chamber vacuum transmitter 62 to control the evaporation vacuum at around -88 kPa.

[0065] The PLC controller is connected to the centrifuge dehydrator 4, the concentrate regulating valve, and the online conductivity meter of the concentrate.

[0066] The following details the system startup and shutdown procedures: The specific operations are as follows:

[0067] At startup:

[0068] Check that the water level in condensate tank 3 is >70% and that valves on jet pump 33 are fully open;

[0069] Check that the concentrate valve and condensate valve at the bottom of the evaporation chamber are in the "closed" position;

[0070] Confirm that the lubricating oil levels of compressor 21 and the circulating pump are normal and there is no oil leakage;

[0071] Confirm that the emergency stop button has been reset and there are no alarms inside the cabinet;

[0072] The main power switch is closed, the PLC is powered on, and the touch screen displays "System ready";

[0073] Click "Automatic Startup," and the system will automatically execute the following steps in sequence:

[0074] ① Ejector pump 33 is running, establishing a vacuum (target -88kPa).

[0075] ②When the vacuum level is reached, the circulation pump starts;

[0076] ③ The circulating flow rate is stable, and compressor 21 starts;

[0077] ④ When the evaporation temperature rises to 46℃, the feed valve is opened and water begins to enter;

[0078] ⑤ The condensate valve automatically discharges intermittently based on the liquid level;

[0079] ⑥ After the startup process stabilizes, the touchscreen displays "Running".

[0080] During normal shutdown:

[0081] Click "Automatic Shutdown," and the system will perform the shutdown sequentially.

[0082] ① Close the feed valve and continue evaporation until the liquid level is low;

[0083] ②Stop compressor 21, and stop circulating pump after a 30-second delay;

[0084] ② Open the condensate valve to drain the liquid, and open the concentrate valve to drain it into the ton container;

[0085] ④ Turn off jet pump 33 to break the vacuum.

[0086] Disconnect the power supply to electric heater 26 and turn off the main power switch;

[0087] Rinse the evaporation chamber with pure water for 5 minutes, then drain it into the ton container.

[0088] The above description is merely a preferred embodiment of the present utility model and is not intended to limit the present utility model in any way. Although the present utility model has been disclosed above with reference to a preferred embodiment, it is not intended to limit the present utility model. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present utility model. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present utility model without departing from the scope of the present utility model shall still fall within the scope of the present utility model.

Claims

1. A heat pump low-temperature evaporation system, characterized in that, include A heat pump cycle system includes a compressor, a first heat exchange tube, a condenser, an expansion valve, and an evaporator. The condenser contains a second heat exchange tube, and the evaporator contains a third heat exchange tube. A low-temperature vacuum evaporator includes a low-temperature vacuum tank, multiple feed nozzles, a circulation pipe, and a scraper device. Each feed nozzle is distributed inside the low-temperature vacuum tank and connected to a wastewater inlet pipe. The circulation pipe connects the wastewater inlet pipe and the concentrate outlet pipe. The first heat exchange tube is installed inside the low-temperature vacuum tank and is used to provide the evaporation temperature. The condenser is installed on the wastewater inlet pipe and is used to heat the raw water. The top of the low-temperature vacuum tank is connected to the top pipe of the evaporator tank. A condensate tank is connected to the evaporator tank via a condensate pipe. A water jet is installed on the condensate pipe to evacuate the low-temperature vacuum tank and the evaporator tank. The water inlet of the water jet is connected to a jet pump, which is connected to the condensate tank. The outlet of the condensate tank is connected to a filter via a pipe.

2. The heat pump low-temperature evaporation system according to claim 1, characterized in that, Also includes A crystallized salt collection system includes a centrifugal dehydrator, a concentrate drain pipe, and a return pipe. The concentrate drain pipe is connected to a low-temperature vacuum tank and a centrifugal dehydrator, and the return pipe is connected to a centrifugal dehydrator and a wastewater storage tank.

3. The heat pump low-temperature evaporation system according to claim 1, characterized in that, A fourth heat exchange tube is installed inside the condensate tank, and the fourth heat exchange tube is connected to the cooling tower.

4. The heat pump low-temperature evaporation system according to claim 1, characterized in that, A flow switch is installed on the circulation pipe.

5. The heat pump low-temperature evaporation system according to claim 1, characterized in that, An electric heater is installed on the pipeline between the condenser and the expansion valve.

6. The heat pump low-temperature evaporation system according to claim 1, characterized in that, The filter is an activated carbon filter or a reverse osmosis filter.

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