Waste heat recovery water source heat pump hot water system suitable for wide-range change of heat source temperature

Abstract

The utility model discloses a waste heat recovery water source heat pump hot water system suitable for wide-range change of heat source temperature. The waste heat recovery water source heat pump hot water system is composed of a waste water tank, an automatic back-flushing cleaning device, a heating device, a pollution discharge filter and a hot water tank. According to the characteristics of high-temperature bathing wastewater discharged in the industries of textile, printing and dyeing and the like, the wastewater-clear water heat exchanger and the automatic filter are mounted at the front end of the water source heat pump, the wastewater and clear water flow regulating valves and the temperature sensor are mounted on the pipeline, and the wastewater is used as a heat source through corresponding heating, cleaning, flow and temperature automatic control schemes; clean water is heated, and hot water and waste water output with stable temperature are obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of industrial waste heat recovery, and specifically relates to a water source heat pump hot water system for utilizing waste heat in wastewater of different temperatures after process discharge in printing and dyeing, papermaking, slaughtering and other enterprises. Background Art

[0002] Printing and dyeing, papermaking, slaughtering and other enterprises have a large amount of waste hot water discharge and a large demand for hot water (above 50°C). The hot water demand temperature of each process section is different, and the temperature of the discharged wastewater varies greatly. When it is low, it is only about 30°C, and when it is high, the discharge temperature is about 40-60°C, and some are even as high as 70-90°C or above. In most cases, it is higher than the discharge temperature of bathing wastewater (about 30°C), so it is not suitable to directly use the existing waste heat cascade to utilize water source heat pump water heaters to recover waste heat.

[0003] In addition, in addition to impurities such as fabric fibers and dye auxiliaries, these wastewaters also contain a large amount of heat energy. If high-temperature wastewater is discharged directly, it will cause great harm to the environment and human life. Therefore, before the final discharge, the wastewater needs to be purified, and biological methods are usually used. Therefore, the core of the wastewater treatment process lies in the activity of the microbial flora. Most microbial flora are most active at around 20-30°C, which is also the most suitable temperature for the highest treatment efficiency. When it exceeds this temperature range, the efficiency will decrease. When the temperature exceeds 40°C, most microbial flora will be inhibited or even inactivated. Similarly, when it is below 8°C, most microbial flora will enter a dormant state and cannot carry out normal biochemical activities. Therefore, while utilizing the high-temperature waste heat in the wastewater, according to the instant wastewater temperature, the clean water flow, hot water outlet temperature and wastewater discharge temperature are adjusted in real time, and the wastewater can be quickly reduced to a suitable temperature without waiting for natural cooling. This is one of the technical problems that technicians in the field urgently need to solve. Utility Model Content

[0004] According to the characteristics of high-temperature bathing wastewater discharged by textile, printing and dyeing industries, the utility model installs a wastewater-clean water heat exchanger and an automatic filter at the front end of the water source heat pump, and installs wastewater and clean water flow regulating valves and temperature sensors on the pipeline. Through the corresponding heating, cleaning, flow and temperature automatic control schemes, the wastewater is used as the heat source to heat the clean water and obtain hot water and wastewater output with stable temperature. The technical solutions provided by the utility model are as follows:

[0005] A waste heat recovery water source heat pump hot water system suitable for a wide range of heat source temperature changes, consisting of a waste water tank, an automatic backwash cleaning device, a heating device, a sewage filter, and a hot water tank. The automatic backwash cleaning device consists of a valve I, a valve II, and an exhaust valve, which are connected in sequence; the heating device consists of a heat exchanger and a water source heat pump, the waste water channel outlet of the heat exchanger is connected to the inlet of the evaporator of the water source heat pump, the outlet of the evaporator is connected to a sewage discharge pipe, valve IV and temperature sensor I are respectively provided on the sewage discharge pipe, the clean water channel outlet of the heat exchanger is connected to the inlet of the evaporator of the water source heat pump, the evaporator outlet is connected to the hot water tank, and a temperature sensor II is provided on the connecting pipe between the two; the waste water tank, The sewage filter and the heat exchanger are connected in sequence, a valve III and a water pump are arranged between the waste water tank and the sewage filter, a connecting pipeline is arranged between the valve III and the water pump and between the valve I and the valve II, a valve V is arranged between the sewage filter and the heat exchanger, the sewage filter is also connected to the outlet of the evaporator, and a valve VI is arranged on the connecting pipeline between the two; the valve I is connected to the water pump; it also includes a clean water supply pipeline connected to the clean water channel inlet of the heat exchanger, and a valve VII is arranged on the connecting pipeline between the two; the exhaust valve is connected to the waste water channel inlet of the heat exchanger; it also includes a PLC control system, and valves I, valve II, valve III, valve IV, valve V, valve VI, VII, temperature sensor I, and temperature sensor II are connected to the PLC control system.

[0006] Preferably, the sewage filter is an automatic sewage filter, a pressure sensor is arranged inside, and an automatic sewage valve is connected at the bottom.

[0007] Preferably, valve V and valve VII are automatic regulating valves, and valve I, valve II, valve III, valve IV and valve VI are automatic switching valves.

[0008] Preferably, it also includes a cleaning liquid storage device, which is composed of a cleaning liquid storage tank, a maintenance valve, and a cleaning liquid water supply pump connected in sequence. The cleaning liquid water supply pump is connected to valve I, the cleaning liquid storage tank is connected to the clean water supply pipe, and a cleaning liquid concentrate injection port is also provided.

[0009] Preferably, the cleaning fluid storage tank is provided with a cleaning fluid level sensor.

[0010] Preferably, a wastewater level sensor is provided in the wastewater tank, and a hot water level sensor is provided in the hot water tank.

[0011] Compared with the prior art, the utility model has the following technical advantages:

[0012] 1. The automatic sewage filter used in the utility model can filter the dirt flowing into the system in real time, and determine the degree of blockage of the filter according to the water pressure difference between the inlet and outlet of the filter. When the blockage reaches a certain standard, the dirt in the filter is automatically discharged from the bottom. The whole process is convenient and fast, and the system operates normally without stopping the machine. In addition, the automatic backwash cleaning device in the system automatically sets the time according to the demand, and the system automatically starts the cleaning work. It can be used for short-term drug-free (cleaning agent) cleaning, and long-term drug-added cleaning. Just add a few valves to clean and remove the dirt attached to the inner wall of the pipe and evaporator in time, without the need to use additional dirt cleaning devices, saving a lot of human resources and production costs.

[0013] 2. The utility model realizes full-process automatic control. No matter how the wastewater temperature changes, it can output hot water with stable temperature and flow according to the company's hot water demand and wastewater discharge temperature demand. At the same time, it can also adjust the wastewater temperature to the most suitable temperature for wastewater treatment, which is convenient for subsequent sewage treatment and discharge. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is the operating principle diagram of the utility model, in which: 1, wastewater tank 2, temperature sensor II 3-electric switch valve III 4, wastewater pump 5, automatic sewage filter 6, electric regulating valve V 8, wastewater channel 9, evaporator 10, electric switch valve IV 11, electric regulating valve VII 13, clean water channel 14, condenser 15, hot water tank 16, electric switch valve VI 17, electric switch valve I 18, electric switch valve II 19, exhaust valve 20, automatic sewage valve 21, heat exchanger 22, water source heat pump 23, cleaning liquid stock liquid injection port 24, cleaning liquid storage tank 25, maintenance valve 26, cleaning liquid water supply pump 27, cleaning liquid level sensor 28, temperature sensor I 29, pressure difference sensor 30, wastewater level sensor 31, hot water level sensor. DETAILED DESCRIPTION

[0015] The utility model is now further described in conjunction with specific embodiments.

[0016] like Figure 1As shown, the utility model discloses a waste heat recovery water source heat pump hot water system suitable for a wide range of heat source temperature changes, which is composed of a waste water tank 1, an automatic backwash cleaning device, a heating device, an automatic sewage filter 5, and a hot water tank 15. A waste water level sensor 30 is provided in the waste water tank 1, and the heating device is composed of a heat exchanger 21 and a water source heat pump 22. The automatic backwash cleaning device is composed of a cleaning liquid storage tank 24, a maintenance valve 25, a cleaning liquid water supply pump 26, an automatic switch valve I 17, an automatic switch valve II 18, and an exhaust valve 19 connected in sequence. The cleaning liquid storage tank 24 is connected to a clean water supply pipe and is provided with a cleaning liquid stock liquid injection port 23. The cleaning liquid storage tank 24 is provided with a cleaning liquid level sensor 27, and the exhaust valve 19 is connected to the inlet of the waste water channel 8 of the heat exchanger 21.

[0017] The outlet of the wastewater channel 8 of the heat exchanger 21 is connected to the inlet of the evaporator 9 of the water source heat pump 22, and the outlet of the evaporator 9 is connected to the sewage discharge pipe, on which an automatic switch valve IV10 and a temperature sensor I28 are respectively provided. The outlet of the clean water channel 13 of the heat exchanger 21 is connected to the inlet of the condenser 14 of the water source heat pump 22, and the outlet of the condenser 14 is connected to the hot water tank 15, and a temperature sensor II2 is provided on the connecting pipeline between the two. The hot water tank 15 is connected to the hot water supply pipe, and a hot water level sensor 31 is also provided on the hot water tank 15.

[0018] The wastewater tank 1, the automatic sewage filter 5, and the heat exchanger 21 are connected in sequence. An automatic switching valve III3 and a wastewater pump 4 are provided between the wastewater tank 1 and the automatic sewage filter 5. An automatic regulating valve V6 is provided between the automatic sewage filter 5 and the heat exchanger 21. The automatic sewage filter 5 is also connected to the outlet of the evaporator 9, and an automatic switching valve VI16 is provided on the connecting pipeline between the two. A connecting pipeline is provided between the automatic switching valve III3 and the wastewater pump 4 and between the automatic switching valve I17 and the automatic switching valve II18.

[0019] It also includes a clean water supply pipeline, which is connected to the clean water channel 13 inlet of the heat exchanger 21, and an automatic regulating valve Ⅶ11 is arranged on the connecting pipeline between the two; it also includes a PLC control system, automatic switch valve Ⅰ17, automatic switch valve Ⅱ18, automatic switch valve Ⅲ3, automatic switch valve Ⅳ10, automatic regulating valve Ⅴ6, automatic switch valve Ⅵ16, automatic regulating valve Ⅶ11, temperature sensor Ⅰ, temperature sensor Ⅱ2, hot water level sensor 31, cleaning liquid level sensor 27, waste water level sensor 30, waste water pump 4, cleaning liquid supply pump 26 are connected to the PLC control system.

[0020] The automatic sewage filter 5 used in the present invention is internally provided with a filter inlet and outlet pressure difference sensor 29, and an automatic sewage valve 20 is provided at the bottom. The pressure difference sensor 29 and the automatic sewage valve 20 are both connected to the PLC control system. When in use, when the PLC control system detects that the inlet and outlet pressure difference of the automatic sewage filter increases to a specified value, the filter cleaning motor starts to drive the wire mesh cleaning brush to rotate and clean the filter. When the pressure difference decreases to a specified value, the sewage valve at the bottom of the filter automatically opens to discharge sewage. After the sewage is discharged for a specified period of time, the cleaning motor and the sewage valve are automatically closed, and the sewage discharge ends. The automatic sewage filter is a technology that has been disclosed in the art, so the present invention does not make too much description.

[0021] 1. Several operating modes of the utility model are now described.

[0022] 1. Hot water making mode

[0023] Here’s how to do it:

[0024] (1) Electric switch valve III3 is open, wastewater pump 4 is open, electric regulating valve V6 is open, water source heat pump 22 is open, electric switch valve IV10 is open; electric regulating valve VII11 is open.

[0025] (2) The wastewater is discharged into the drainage ditch through the wastewater tank 1, the electric switch valve III3, the wastewater pump 4, the electric switch valve V6, the heat exchanger 21, the water source heat pump 22, the electric switch valve IV10, and then discharged into the drainage ditch for subsequent unified treatment.

[0026] (3) The clean water passes through the electric regulating valve VII11, the heat exchanger 21, the water source heat pump 22, and finally enters the hot water tank 15.

[0027] 2. Backwash cleaning mode

[0028] To clean without cleaning fluid, proceed as follows:

[0029] (1) The water source heat pump 22 is turned off, the electric switch valve VI 16 is opened, the electric switch valve II 18 is opened, and all other electric valves are closed. The wastewater pump 4 is started, and the backwash cleaning is completed after 10 minutes.

[0030] To clean with cleaning fluid, follow the steps below:

[0031] (1) The electric switch valve III3 is closed, the wastewater pump 4 is closed, the electric switch valve I17 is closed, the water source heat pump 22 is closed, the electric regulating valve VII11 is closed, and other electric valves are opened. The wastewater in the system is discharged into the drain through the electric switch valve IV10, and the external air enters the system through the automatic air inlet and outlet valve 19 to fully drain the wastewater. The draining time is determined by the timer T1 (T1 is generally 1 to 20 minutes).

[0032] (2) After the system wastewater is drained, the electric switch valve Ⅳ10 closes, the electric control valve Ⅴ6 closes, the electric switch valve Ⅰ17 opens, and the cleaning liquid supply pump 26 opens. Inject the cleaning liquid in the cleaning liquid storage tank 24 into the system through the electric switch valve Ⅰ17 until it is full. For all parts through which the wastewater passes, including the wastewater pipeline, the wastewater channel of the evaporator 9, the wastewater pump 4, and the automatic sewage filter 5, the system injects 1 liter of cleaning liquid per 1P water source heat pump. Taking the company's 42P water source heat pump as an example, 42 liters of cleaning liquid need to be injected. When injecting, determine the injected amount through the change in the water level of the cleaning liquid storage tank 24, that is, multiply the water level drop value (unit: m) of the cleaning liquid storage tank 24 by the cross-sectional area of the water tank (unit: m 2 ), and the volume of the injected cleaning liquid (unit: m 3 ) can be obtained. When the water volume reaches the required 42 liters (0.042 m 3 ), stop injecting: close the electric switch valve Ⅰ17 and the cleaning liquid supply pump 26.

[0033] (3) Start the wastewater pump 4 to carry out the backwashing cleaning cycle, and the time is determined according to the set duration T2 (T2 generally takes 5 - 30 minutes).

[0034] (4) After the backwashing cleaning cycle ends, the system stands still for 1h to wait for the dirt to dissolve sufficiently, then start the wastewater pump 4 again for backwashing cleaning, and the duration is the same as the first time. After the second backwashing cleaning cycle ends, drain the wastewater according to the method and steps in item (1).至此, the backwashing cleaning is all completed.

[0035] Whether with cleaning liquid or not, during the cleaning period, the automatic sewage valve 20 remains closed.

[0036] Second, several control methods for the operation of the present utility model will be described.

[0037] 1. Start and stop of the water source heat pump.

[0038] There are two control values for the corresponding wastewater liquid level: h1high and h1low, and the effective height of the wastewater tank > h1high > h1low > 0; there are two control values for the corresponding clean water liquid level: h2high and h2low, and the effective height of the hot water tank > h2high > h2low > 0.

[0039] (1) When h1 > h1high and h2 < h2low, the water source heat pump starts.

[0040] (2) When h1 < h1low or h2 > h2high, the water source heat pump stops.

[0041] 2. Start and stop of automatic sewage discharge.

[0042] There are two control values for the pressure difference between the inlet and outlet of the corresponding automatic sewage filter: Pmax, Pmin.

[0043] When the value of p1 > Pmax, the cleaning motor of the filter starts to drive the wire mesh cleaning brush to rotate to clean the filter screen. When the value of p1 < Pmin, the sewage discharge valve at the bottom of the filter automatically opens for sewage discharge. After the sewage discharge reaches the duration of T3 (such as 60 seconds, a reasonable value is selected after debugging according to the on-site working conditions), the cleaning motor and the sewage discharge valve automatically close, and the sewage discharge ends.

[0044] 3. Automatic control of the outlet water temperature of clear water and wastewater.

[0045] (I) Parameter description:

[0046] a - Input value of the electric control valve VII for clear water. For valves with input current signals, it refers to the input current value; for valves with input voltage signals, it refers to the input voltage value.

[0047] b - Input value of the electric control valve V for wastewater. For valves with input current signals, it refers to the input current value; for valves with input voltage signals, it refers to the input voltage value.

[0048] t1 - Outlet water temperature of hot water

[0049] t2 - Wastewater discharge temperature

[0050] tfmin - Lower limit of wastewater discharge temperature, for example: 20 °C

[0051] tfmax - Upper limit of wastewater discharge temperature, for example: 25 °C

[0052] tqmin - Lower limit of outlet water temperature of hot water, for example: 50 °C

[0053] tqmax - Upper limit of outlet water temperature of hot water, for example: 55 °C

[0054] tfmin, tfmax, tqmin, and tqmax should be set according to the on-site working conditions and the actual requirements of the enterprise during actual operation.

[0055] (II) Judgment of the adjustment direction

[0056]

[0057] (III) Calculation method for the target adjustment values of a and b

[0058] (1) Parameter description:

[0059] Target value of the outlet water temperature of hot water: tqavg = (tqmin + tqmax) ÷ 2

[0060] Target value of the wastewater discharge temperature: tfavg = (tfmin + tfmax) ÷ 2

[0061] The current or voltage range corresponding to the electric control valve fully open to fully closed is: n0~n1. For example: for a valve with a common input current signal of 4-20ma, n0=4ma, n1=20ma.

[0062] According to the working conditions and performance characteristics of the water source heat pump, it is assumed that the fresh water outlet temperature range of the water source heat pump is 30℃~65℃, and the waste water outlet temperature range is 3℃~35℃.

[0063] (2) (Clean water) Electric regulating valve VII adjustment method

[0064] Reduce a: target value of a = ak × (a-n0) / (65°C-t1) × (tqavg-t1)

[0065] Increase a: target value of a = a + k × (n1-a) / (t1-30°C) × (t1-tqavg)

[0066] (3) (Wastewater) Electric regulating valve V adjustment method

[0067] Reduce b: b target value = bk × (b-n0) / (t2-3℃) × (t2-tfavg)

[0068] Increase b: b target value = b + k × (n1-b) / (35°C-t2) × (tfavg-t2)

[0069] (4) The value of k is 0.85-0.3, which is determined through field tests. A larger value is preferred, which results in faster adjustment.

[0070] (5) If the fresh water outlet temperature or waste water discharge temperature of the water source heat pump exceeds the assumed range (fresh water outlet temperature range 30℃~65℃, waste water discharge temperature range 3℃~35℃), it is necessary to set a lower limit for the calculation results of a and b. For example: for a valve with an input current signal of 4-20ma, when the calculation result of a or b is lower than 5ma, 5ma is used to ensure that the valve will not be completely closed.

[0071] (IV) Implementation of temperature regulation.

[0072] The system controller cyclically reads and detects the hot water outlet temperature t1 and wastewater discharge temperature t2 of the water source heat pump, and calculates the target value a and the target value b according to the aforementioned calculation method and outputs them to the corresponding electric control valve VII and electric control valve V. After waiting for the valve to be in place, t1 and t2 are detected again. This cycle is repeated. After multiple adjustments, t1 and t2 will reach the expected temperature range.

[0073] (V) Automatic control of recoil cleaning.

[0074] (1) The control system accumulates the working time of the water source heat pump equipment (saved as C1 and C2). When C1 reaches 24 hours, the heat pump will shut down and automatically enter the "cleaning without cleaning fluid" mode. After the cleaning is completed, it will automatically return to the working state before the shutdown, and set C1 to 0, and re-accumulate C1.

[0075] (2) When C2 reaches 168h, the water source heat pump will shut down and automatically enter the "cleaning with cleaning fluid" mode. After the cleaning is completed, it will automatically return to the working state before the shutdown, and set C1 and C2 to 0, and re-accumulate C1 and C2.

[0076] (3) C1 and C2 users can change the settings in the PLC.

Claims

1. A waste heat recovery water source heat pump hot water system suitable for a wide range of heat source temperature changes, characterized in that: It is composed of a wastewater tank, an automatic backwash cleaning device, a heating device, a sewage filter, and a hot water tank. The automatic backwash cleaning device is composed of valve I, valve II, and an exhaust valve, which are connected in sequence; the heating device is composed of a heat exchanger and a water source heat pump. The wastewater channel outlet of the heat exchanger is connected to the inlet of the evaporator of the water source heat pump, and the outlet of the evaporator is connected to the sewage discharge pipe. The sewage discharge pipe is respectively provided with valve IV and temperature sensor I. The clean water channel outlet of the heat exchanger is connected to the inlet of the evaporator of the water source heat pump, and the outlet of the evaporator is connected to the hot water tank. A temperature sensor II is provided on the connecting pipe between the two; the wastewater tank, the sewage filter, and the heat exchanger are connected in sequence A valve III and a water pump are arranged between the waste water tank and the sewage filter, a connecting pipeline is arranged between the valve III and the water pump and between the valve I and the valve II, a valve V is arranged between the sewage filter and the heat exchanger, the sewage filter is also connected to the outlet of the evaporator, and a valve VI is arranged on the connecting pipeline between the two; the valve I is connected to the water pump; it also includes a clean water supply pipeline connected to the clean water channel inlet of the heat exchanger, and a valve VII is arranged on the connecting pipeline between the two; the exhaust valve is connected to the waste water channel inlet of the heat exchanger; it also includes a PLC control system, and valves I, valve II, valve III, valve IV, valve V, valves VI, VII, temperature sensor I, and temperature sensor II are connected to the PLC control system.

2. A waste heat recovery water source heat pump hot water system suitable for a wide range of heat source temperature changes according to claim 1, characterized in that: The sewage filter is an automatic sewage drainer, which is provided with a pressure sensor inside and an automatic sewage valve connected at the bottom.

3. A waste heat recovery water source heat pump hot water system suitable for a wide range of heat source temperature changes according to claim 1, characterized in that: Valves V and VII are automatic regulating valves, and valves I, II, III, IV and VI are automatic switching valves.

4. A waste heat recovery water source heat pump hot water system suitable for a wide range of heat source temperature changes according to claim 1, characterized in that: It also includes a cleaning liquid storage device, which is composed of a cleaning liquid storage tank, a maintenance valve, and a cleaning liquid water supply pump connected in sequence. The cleaning liquid water supply pump is connected to valve I, the cleaning liquid storage tank is connected to the clean water supply pipe, and is also provided with a cleaning liquid concentrate injection port.

5. A waste heat recovery water source heat pump hot water system suitable for a wide range of heat source temperature changes according to claim 4, characterized in that: The washer fluid storage tank is provided with a washer fluid level sensor.

6. A waste heat recovery water source heat pump hot water system suitable for a wide range of heat source temperature changes according to claim 1, characterized in that: A wastewater level sensor is provided in the wastewater tank, and a hot water level sensor is provided in the hot water tank.

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