Heat pump system for boiler flue gas waste heat recovery

Abstract

The utility model relates to the technical field of heat exchange equipment, in particular to a heat pump system for boiler flue gas waste heat recovery, which comprises a flue gas circulation loop, a heat exchange loop, a plate heat exchanger I, a flue gas source heat pump, a plate heat exchanger II and a use side loop, the two-stage heat exchange process is adopted, heat energy in the flue gas of the gas-fired boiler is recycled in a stepped mode, and the flue gas heat recycling rate is greatly increased.

Description

TECHNICAL FIELD

[0001] The utility model relates to heat exchange equipment technical field, concretely is a kind of heat pump system for boiler flue gas waste heat recovery. BACKGROUND

[0002] The steam required in the processes of beer saccharification, wort boiling, bottle washing machine, sterilization machine and the like is currently mostly obtained by gas-fired boiler, and the temperature of the flue gas of the boiler after passing through the coal economizer is about 100 DEG C, a large amount of sensible heat and latent heat in the flue gas is discharged into the air, causing waste of heat energy.

[0003] At present, the boiler flue gas waste heat recovery technology mostly adds a plate heat exchanger (plate exchanger), and in the plate heat exchanger, water exchanges heat with the flue gas discharged from the chimney, so that the temperature of the flue gas is reduced to about 80 DEG C and discharged into the atmosphere, while the condensation temperature of the flue gas is 59 DEG C, and below this temperature, the sulfides and nitrogen oxides in the flue gas are condensed in the water to form sulfuric acid and nitric acid, causing corrosion to the flue, so in this waste heat recovery mode, the latent heat (below 59 DEG C) in the flue gas after cooling is not recovered, causing waste of energy. SUMMARY

[0004] The utility model provides a kind of heat pump system for boiler flue gas waste heat recovery, the utility model uses two-stage heat exchange process, and the heat energy in the flue gas of gas-fired boiler is recovered and utilized in cascade, greatly improves flue gas heat recovery utilization rate.

[0005] To achieve the above object, the utility model provides the following technical scheme: a heat pump system for boiler flue gas waste heat recovery, comprising a flue gas flow circuit, a heat exchange circuit, a plate heat exchanger one, a flue gas source heat pump, a plate heat exchanger two and a use side circuit.

[0006] The flue gas flow circuit comprises a high-temperature flue gas inlet pipe, a fan and a low-temperature flue gas outlet pipe connected in series, and the flue gas in the chimney enters from the high-temperature flue gas inlet pipe under the guidance of the fan, passes through the plate heat exchanger one and the flue gas source heat pump, and flows back to the chimney from the low-temperature flue gas outlet pipe.

[0007] The heat exchange circuit comprises a first circulating pump and a water tank connected in series, and the water inlet pipe of the first circulating pump is connected to the bottom of the water tank.

[0008] The plate heat exchanger one is provided with a plate exchanger one air inlet, a plate exchanger one air outlet, a plate exchanger one water inlet and a plate exchanger one water outlet, the plate exchanger one air inlet is connected to the fan, the plate exchanger one air outlet is connected to the flue gas source heat pump, the high-temperature flue gas enters from the plate exchanger one air inlet and is discharged from the plate exchanger one air outlet, the plate exchanger one water inlet is connected to the drain pipe of the first circulating pump, the plate exchanger one water outlet is connected to the upper part of the water tank, the water of the heat exchange circuit enters from the plate exchanger one water inlet and is discharged from the plate exchanger one water outlet, and the high-temperature flue gas heats the water in the heat exchange circuit once in the plate heat exchanger one.

[0009] The evaporation side of the flue gas source heat pump is provided with a heat pump flue gas inlet and a heat pump flue gas outlet, the heat pump flue gas inlet is connected with an exhaust port of the plate heat exchanger, the flue gas after primary temperature reduction enters the heat pump flue gas inlet and is discharged from the heat pump flue gas outlet, and the flue gas exchanges heat with the evaporator at the evaporation side of the flue gas source heat pump; the condensation side of the flue gas source heat pump is provided with a heat pump water inlet and a heat pump water outlet, the heat pump water inlet is connected with a water outlet pipe of the first circulating pump, and the heat pump water outlet is connected with an upper portion of the water tank; water of the heat exchange circuit enters the heat pump water inlet and is discharged from the heat pump water outlet, and the condenser of the flue gas source heat pump performs secondary heating on the water in the heat exchange circuit.

[0010] The second plate heat exchanger is provided with a second plate heat exchanger hot inlet, a second plate heat exchanger hot outlet, a second plate heat exchanger cold inlet and a second plate heat exchanger cold outlet, the second plate heat exchanger hot inlet is connected with the upper portion of the water tank, a second circulating pump is arranged between the second plate heat exchanger hot inlet and the water tank, and the second plate heat exchanger hot outlet is connected with a bottom portion of the water tank.

[0011] The use side circuit comprises a use side device and a third circulating pump, a water outlet pipe of the use side device is connected with the second plate heat exchanger cold inlet, a backwater pipe of the use side device is connected with the second plate heat exchanger cold outlet, and the third circulating pump is arranged between the second plate heat exchanger cold inlet and the use side device.

[0012] Further, the first circulating pump is provided with two sets in parallel.

[0013] Further, a water supplement pipe is arranged on the water tank.

[0014] Compared with the prior art, the heat pump system for flue gas waste heat recovery has the beneficial effects that:

[0015] 1. The heat pump system for flue gas waste heat recovery disclosed by the utility model recovers and utilizes the heat of high-temperature flue gas once before the flue gas enters the flue gas source heat pump, and heats the water of the heat exchange circuit once, so that the damage of the evaporator caused by excessively high temperature is prevented; the heat of the flue gas after temperature reduction is recovered and utilized twice at the evaporation side of the flue gas source heat pump, and the water of the heat exchange circuit is heated twice, so that the two-stage heat exchange process is realized, the heat energy in the flue gas of the gas-fired boiler is recovered and utilized in stages, and in particular, the flue gas source heat pump is used to absorb low-grade heat energy, so that the flue gas heat recovery utilization rate is improved.

[0016] Relying on the demand for heat energy and cold energy in beer production, the flue gas source heat pump technology is adopted to absorb the waste heat of the boiler flue gas, and the heat is transmitted to the link requiring steam heating, such as a sterilizer, low steam consumption is realized, cost is saved, and in the process of flue gas temperature reduction, the condensed water condenses part of nitrogen oxides in the flue gas, so that energy saving and emission reduction are realized.

[0017] 2.The heat pump system for boiler flue gas waste heat recovery disclosed in the utility model, heat exchange is carried out between the use side circuit and the water tank through the second plate heat exchanger, the corrosion of impurities in the water tank to the use side circuit pipeline is avoided, and the cleanliness of water for the use side equipment is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The utility model discloses a principle block diagram.

[0019] Main element symbol explanation:

[0020] 11-high temperature flue gas inlet pipe, 12-fan, 13-low temperature flue gas outlet pipe, 14-chimney;

[0021] 21-first circulating pump, 22-water tank, 23-water supply pipe;

[0022] 30-plate heat exchanger one;

[0023] 40-flue gas source heat pump;

[0024] 50-plate heat exchanger two, 51-second circulating pump, 52-plate two heat import, 53-plate two heat export, 54-plate two cold import, 55-plate two cold export;

[0025] 61-use side equipment, 62-third circulating pump. DETAILED DESCRIPTION

[0026] The technical scheme in the embodiments of the utility model will be described clearly and completely in combination with the drawings in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model and not all the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by the person skilled in the art without creative labor fall within the protection scope of the utility model.

[0027] Please refer to Figure 1 The utility model provides a kind of heat pump system for boiler flue gas waste heat recovery, including flue gas flow circulation loop, heat exchange circuit, plate heat exchanger one 30, flue gas source heat pump 40, plate heat exchanger two 50 and use side circuit.

[0028] The flue gas flow circulation loop includes high temperature flue gas inlet pipe 11, fan 12 and low temperature flue gas outlet pipe 13 in series, the flue gas in chimney 14 is guided under fan 12 from high temperature flue gas inlet pipe 11, after plate heat exchanger one 30 and flue gas source heat pump 40, from low temperature flue gas outlet pipe 13 back flow to chimney 14.

[0029] The heat exchange circuit comprises a first circulating pump 21 and a water tank 22 connected in series, the water inlet pipe of the first circulating pump 21 is connected with the bottom of the water tank 22, a water supplement pipe 23 is arranged on the water tank 22, and the water supplement pipe 23 is connected with a tap water pipe network. The first circulating pump 21 in the embodiment is provided with two sets in parallel, one of which is used normally and the other is used as a backup.

[0030] The plate heat exchanger one 30 is provided with a plate one air inlet, a plate one air outlet, a plate one water inlet and a plate one water outlet, the plate one air inlet is connected with the fan 12, the plate one air outlet is connected with the flue gas source heat pump 40, high-temperature flue gas enters from the plate one air inlet and is discharged from the plate one air outlet, the plate one water inlet is connected with the water outlet pipe of the first circulating pump 21, and the plate one water outlet is connected with the upper portion of the water tank 22. The water in the heat exchange circuit enters from the plate one water inlet and is discharged from the plate one water outlet, and the high-temperature flue gas is once heated in the plate heat exchanger one 30 and is once cooled at the same time.

[0031] The evaporation side of the flue gas source heat pump 40 is provided with a heat pump flue gas inlet and a heat pump flue gas outlet, the heat pump flue gas inlet is connected with the plate one air outlet, the once cooled flue gas enters from the heat pump flue gas inlet and is discharged from the heat pump flue gas outlet, and is heat-exchanged with the evaporator at the evaporation side of the flue gas source heat pump 40, and the flue gas is twice cooled; the condensation side of the flue gas source heat pump 40 is provided with a heat pump water inlet and a heat pump water outlet, the heat pump water inlet is connected with the water outlet pipe of the first circulating pump 21, and the heat pump water outlet is connected with the upper portion of the water tank 22. The water in the heat exchange circuit enters from the heat pump water inlet and is discharged from the heat pump water outlet, and the condenser of the flue gas source heat pump is twice heated for the water in the heat exchange circuit.

[0032] It should be noted that a mixed cooler is arranged in the flue gas source heat pump 40, and the function of the mixed cooler can refer to the scheme of the application No. CN200810188037.6. The mixed cooler is located between the heat pump flue gas inlet and the plate one air outlet, the mixed cooler cools the flue gas (about 60℃) to 30-40℃, and guarantees the safety of the pipeline of the flue gas source heat pump 40.

[0033] The plate heat exchanger two 50 is provided with a plate two hot inlet 52, a plate two hot outlet 53, a plate two cold inlet 54 and a plate two cold outlet 55, the plate two hot inlet 52 is connected with the upper portion of the water tank 22, a second circulating pump 51 is arranged between the plate two hot inlet 52 and the water tank 22, and the plate two hot outlet 53 is connected with the bottom of the water tank 22.

[0034] The use side circuit comprises a use side device 61 and a third circulating pump 62, the outlet water pipe of the use side device 61 is connected with the plate heat exchanger two cooling inlet 54, the third circulating pump 62 is arranged between the plate heat exchanger two cooling inlet 54 and the use side device 61, and the return water pipe of the use side device 61 is connected with the plate heat exchanger two cooling outlet 55.

[0035] The working principle of the utility model is:

[0036] The fan 12 draws part of flue gas from the chimney 14 to enter the plate heat exchanger one 30 first, the high-temperature flue gas heats the water in the heat exchange circuit once in the plate heat exchanger one 30, the cooled flue gas enters the flue gas source heat pump again, the condenser of the flue gas source heat pump heats the water in the heat exchange circuit twice, and finally the low-temperature flue gas is discharged into the original chimney 14 and then discharged into the atmosphere.

[0037] The second circulating pump 51 draws the hot water at the upper portion of the water tank 22 to enter the plate heat exchanger two 50, and then the heat is transferred to the cold water of the use side, and the return water is at the bottom of the water tank 22; the third circulating pump 62 draws the water of the use side device 61, and then the water is heated in the plate heat exchanger two 50 and returned to the use side device 61.

[0038] Although the embodiments of the utility model have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the utility model, and the scope of the utility model is defined by the appended claims and their equivalents.

Claims

1. A heat pump system for recovering waste heat from boiler flue gas, characterized in that: It includes a flue gas circulation loop, a heat exchange loop, a plate heat exchanger I, a flue gas source heat pump, a plate heat exchanger II, and a user-side loop. The flue gas circulation loop includes a high-temperature flue gas inlet pipe, a fan, and a low-temperature flue gas outlet pipe connected in series. The flue gas in the chimney enters from the high-temperature flue gas inlet pipe under the guidance of the fan, passes through the plate heat exchanger and the flue gas source heat pump, and flows back into the chimney from the low-temperature flue gas outlet pipe. The heat exchange circuit includes a first circulating pump and a water tank connected in series, with the inlet pipe of the first circulating pump connected to the bottom of the water tank. The plate heat exchanger is provided with an air inlet, an exhaust outlet, a water inlet, and a water outlet. The air inlet is connected to a fan, and the exhaust outlet is connected to a flue gas source heat pump. High-temperature flue gas enters through the air inlet and exits through the exhaust outlet. The water inlet is connected to the drain pipe of the first circulating pump, and the water outlet is connected to the upper part of the water tank. Water in the heat exchange circuit enters through the water inlet and exits through the water outlet. The high-temperature flue gas heats the water in the heat exchange circuit once within the plate heat exchanger. The evaporator side of the flue gas source heat pump is provided with a heat pump flue gas inlet and a heat pump flue gas outlet. The heat pump flue gas inlet is connected to the exhaust port of the plate heat exchanger. The flue gas after primary cooling enters through the heat pump flue gas inlet and exits through the heat pump flue gas outlet, and exchanges heat with the evaporator on the evaporator side of the flue gas source heat pump. The condenser side of the flue gas source heat pump is provided with a heat pump water inlet and a heat pump water outlet. The heat pump water inlet is connected to the drain pipe of the first circulation pump, and the heat pump water outlet is connected to the upper part of the water tank. The water in the heat exchange circuit enters through the heat pump water inlet and exits through the heat pump water outlet. The condenser of the flue gas source heat pump performs secondary heating on the water in the heat exchange circuit. The plate heat exchanger 2 is provided with a heat inlet, a heat outlet, a cold inlet, and a cold outlet. The heat inlet is connected to the upper part of the water tank. A second circulation pump is provided between the heat inlet and the water tank. The heat outlet is connected to the bottom of the water tank. The user-side circuit includes user-side equipment and a third circulation pump. The outlet pipe of the user-side equipment is connected to the inlet of the plate heat exchanger secondary cooling system, and the return pipe of the user-side equipment is connected to the outlet of the plate heat exchanger secondary cooling system. A third circulation pump is installed between the inlet of the plate heat exchanger secondary cooling system and the user-side equipment.

2. The heat pump system for boiler flue gas waste heat recovery according to claim 1, characterized in that: The first circulating pump is installed in two sets in parallel.

3. The heat pump system for boiler flue gas waste heat recovery according to claim 1 or 2, characterized in that: A water supply pipe is installed on the water tank.

Images