Energy recycling system for malt industry

Abstract

The invention discloses an energy recycling system for the malt industry. The energy recycling system comprises a first hot water heat pump, a second hot water heat pump, a plate heat exchanger, an energy storage tank, a steam condensation water tank, a micro-pressure steam heat pump and a steam compressor. A heat pump system is used for transformation, and a heat pump is a device for increasing heat from low temperature to high temperature by consuming electric energy and has the advantages of being environmentally friendly, capable of saving energy, economical and convenient to use. The heat pump heat energy system can flexibly adapt to different heating functions and realize low-temperature waste heat recovery in malt factories and other scenes which have high energy utilization rate requirements and need refrigeration and heating at the same time.

Description

Technical Field

[0001] The invention relates to the technical field of energy utilization, in particular to an energy recovery and reuse system for the malt industry. Background Art

[0002] The main energy consumption for malt production is steam. Malt manufacturing can be divided into five processes, namely (including cleaning and grading), steeping, germination, drying and root removal. The three stages of steeping, germination and drying involve the consumption of cold and hot energy. The main hot spots are the maintenance of room temperature in the steeping room and germination room in winter and the drying of malt. The refrigeration station of the malt factory workshop mainly includes centrifugal chillers and York screw chillers. The refrigeration system is responsible for providing cooling capacity, mainly for maintaining a stable temperature in the steeping workshop and germination workshop. The refrigerator is equipped with an open cooling tower, and all condensation heat is directly discharged into the atmosphere. Summary of the invention

[0003] In order to solve the energy loss in malt production and recycle energy, the present invention uses a heat pump system for transformation. A heat pump is a device that increases heat from low temperature to high temperature by consuming electrical energy. It is environmentally friendly, energy-saving, economical and convenient. In scenarios such as malt factories where energy utilization is high and cooling and heating are required at the same time, the heat pump thermal energy system can flexibly adapt to different heating functions and realize low-temperature waste heat recovery.

[0004] The purpose of the present invention is to provide a high-temperature heat pump energy application system, which recovers the waste heat of the circulating water in the cooling tower of the refrigeration room and the heat of the waste water from soaking wheat, uses a small amount of electric energy to drive the high-temperature heat pump to produce medium and high-temperature hot water, and converts part of the hot water into micro-pressure steam, which is then mixed with high-pressure steam to produce medium-pressure steam to supply the process production needs of the malt factory.

[0005] The technical solution of the present invention is as follows:

[0006] An energy recovery and reuse system for the malt industry, comprising a hot water heat pump 1, a hot water heat pump 2, a plate heat exchanger, an energy storage tank, a steam condensing water tank, a micro-pressure steam heat pump and a steam compressor;

[0007] Hot water heat pump 1 is used to recover the waste heat of the circulating water in the cooling tower of the refrigeration room. The inlet and outlet water temperatures are 37°C and 32°C. On the one hand, 70°C hot water is generated by hot water heat pump 1, and the 70°C hot water enters the energy storage tank for storage. On the other hand, the circulating water in the energy storage tank is recovered.

[0008] The plate heat exchanger is used to exchange the heat of the wheat soaking wastewater with the circulating water, mix it with the condensed water in the steam condensate tank and enter the hot water heat pump 2, and on the other hand, receives the circulating water on the evaporator side of the hot water heat pump;

[0009] Hot water heat pump 2, the condensed water in the plate heat exchanger and the steam condensate tank enters the evaporator side of the hot water heat pump 2. On the one hand, 70℃ hot water is generated by the hot water heat pump 2, and the 70℃ hot water enters the energy storage tank for storage. On the other hand, the circulating water in the energy storage tank is recovered;

[0010] Energy storage tank, one branch uses 70℃ hot water, combined with boiler room steam to supplement 70℃ hot water to the heat exchanger of the soaking and germination workshop, replacing the steam consumption of the boiler room of the soaking and germination workshop; the other branch enters the micro-pressure steam heat pump; the energy storage tank also has the function of recycling the circulating water used by the heat exchanger and micro-pressure steam heat pump of the soaking and germination workshop;

[0011] The micro-pressure steam heat pump uses the 70℃ hot water in part of the energy storage tank to produce 0.1Mpa micro-pressure steam, which then enters the steam compressor, and on the other hand, it recovers the condensed water in the heat exchanger in the drying room;

[0012] The steam compressor uses the 0.8-1.0Mpa steam from the boiler room on the one hand, and the 0.1Mpa micro-pressure steam from the micro-pressure steam heat pump on the other hand. After mixing, it produces 0.3Mpa medium-pressure steam, which is supplied to the heat exchanger in the drying room to heat the air inlet in the drying room, replacing the original 0.8Mpa steam consumption in the boiler room for heating the drying section.

[0013] The steam condensate water tank is used to receive the steam used in the drying room heat exchanger, condense it, mix it with the circulating water of the plate heat exchanger and enter the hot water heat pump 2; on the other hand, it receives the circulating water on the evaporator side of the hot water heat pump 2 and recycles it to the boiler room.

[0014] Preferably, the heat recovery capacity of the hot water heat pump 1 is 775 kW, the input power is 225 kW, and the heating capacity is 1000 kW.

[0015] Preferably, the heat recovery capacity of the hot water heat pump 2 is 688.3 kW, the input power is 275 kW, and the heating capacity is 962.5 kW.

[0016] Preferably, the heat recovery capacity of the above-mentioned micro-pressure steam heat pump is 1000kW, the input power is 600kW, and the heating capacity is 1600kW.

[0017] Preferably, the above system also includes a control system for monitoring and controlling the operating status of each component in the system, including the pressure and temperature of steam, the temperature and flow of hot water, the collection and discharge of condensed water, etc., so as to achieve efficient recovery and utilization of energy.

[0018] Preferably, when the high-pressure steam supply pressure of the steam compressor is 0.8 MPa, the steam compressor mixing ratio is 4:1; when the high-pressure steam supply pressure is 1.0 MPa, the steam compressor mixing ratio is 2.5:1.

[0019] The beneficial effects of the present invention include:

[0020] 1. Improve energy utilization efficiency and achieve quality improvement and temperature increase of low-level energy by recycling waste heat resources;

[0021] 2. Reduce energy consumption and reduce dependence on traditional energy;

[0022] 3. The flexibility and adaptability of the system have been improved, and it can be flexibly adjusted according to different heating functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural flow chart of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0025] like Figure 1 As shown, an energy recovery and reuse system for the malt industry includes a hot water heat pump 1, a hot water heat pump 2, a plate heat exchanger, an energy storage tank, a steam condensate tank, a micro-pressure steam heat pump and a steam compressor;

[0026] Hot water heat pump 1 is used to recover the waste heat of the circulating water in the cooling tower of the refrigeration room. The inlet and outlet water temperatures are 37°C and 32°C. On the one hand, 70°C hot water is generated by hot water heat pump 1, and the 70°C hot water enters the energy storage tank for storage. On the other hand, the circulating water in the energy storage tank is recovered.

[0027] The plate heat exchanger is used to exchange the heat of the wheat soaking wastewater with the circulating water, mix it with the condensed water in the steam condensate tank and enter the hot water heat pump 2, and on the other hand, receives the circulating water on the evaporator side of the hot water heat pump;

[0028] Hot water heat pump 2, the condensed water in the plate heat exchanger and the steam condensate tank enters the evaporator side of the hot water heat pump 2. On the one hand, 70℃ hot water is generated by the hot water heat pump 2, and the 70℃ hot water enters the energy storage tank for storage. On the other hand, the circulating water in the energy storage tank is recovered;

[0029] Energy storage tank, one branch uses 70℃ hot water, combined with boiler room steam to supplement 70℃ hot water to the heat exchanger of the soaking and germination workshop, replacing the steam consumption of the boiler room of the soaking and germination workshop; the other branch enters the micro-pressure steam heat pump; the energy storage tank also has the function of recycling the circulating water used by the heat exchanger and micro-pressure steam heat pump of the soaking and germination workshop;

[0030] The micro-pressure steam heat pump uses the 70℃ hot water in part of the energy storage tank to produce 0.1Mpa micro-pressure steam, which then enters the steam compressor, and on the other hand, it recovers the condensed water in the heat exchanger in the drying room;

[0031] The steam compressor uses the 0.8-1.0Mpa steam from the boiler room on the one hand, and the 0.1Mpa micro-pressure steam from the micro-pressure steam heat pump on the other hand. After mixing, it produces 0.3Mpa medium-pressure steam, which is supplied to the heat exchanger in the drying room to heat the air inlet in the drying room, replacing the original 0.8Mpa steam consumption in the boiler room for heating the drying section.

[0032] The steam condensate water tank is used to receive the steam used in the drying room heat exchanger, condense it, mix it with the circulating water of the plate heat exchanger and enter the hot water heat pump 2; on the other hand, it receives the circulating water on the evaporator side of the hot water heat pump 2 and recycles it to the boiler room.

[0033] Preferably, the heat recovery capacity of the hot water heat pump 1 is 775 kW, the input power is 225 kW, and the heating capacity is 1000 kW.

[0034] Preferably, the heat recovery capacity of the hot water heat pump 2 is 688.3 kW, the input power is 275 kW, and the heating capacity is 962.5 kW.

[0035] Preferably, the heat recovery capacity of the above-mentioned micro-pressure steam heat pump is 1000kW, the input power is 600kW, and the heating capacity is 1600kW.

[0036] Preferably, the above system also includes a control system for monitoring and controlling the operating status of each component in the system, including the pressure and temperature of steam, the temperature and flow of hot water, the collection and discharge of condensed water, etc., so as to achieve efficient recovery and utilization of energy.

[0037] Preferably, when the high-pressure steam supply pressure of the steam compressor is 0.8 MPa, the steam compressor mixing ratio is 4:1; when the high-pressure steam supply pressure is 1.0 MPa, the steam compressor mixing ratio is 2.5:1.

[0038] Example:

[0039] A malt company is mainly engaged in the research and development, production and sales of malt. The annual output of malt is about 130,000 tons, and the production energy consumption is mainly steam, with an annual steam consumption of about 130,000 tons. According to the on-site investigation, the basic production situation of the company is as follows:

[0040] Malt production can be divided into five steps, namely (including malt cleaning and grading), malt steeping, germination, drying and root removal.

[0041] The three stages involving the consumption of cold and hot energy in the above processes are mainly soaking wheat, germination and drying.

[0042] The waste heat resources on site are as follows in Table 1:

[0043] Table 1-Summary of waste heat in a malt plant

[0044]

[0045] After waste heat recovery, the 40℃ steam condensate of the biomass boiler, the 23℃ wheat soaking wastewater and the 32℃ cooling tower circulating water waste heat can be recycled.

[0046] The main heat source is steam supplied by a third-party biomass boiler. The steam supply parameters are low-pressure saturated steam (0.8MPa). The unit price of steam is 340-360 yuan / ton. The main hot spots are the maintenance of room temperature in the soaking room and germination room in winter and malt drying, as shown in Table 2.

[0047] Table 2-Summary of heat usage in a malt factory

[0048]

[0049]

[0050] The workshop refrigeration station is equipped with 3 Carrier centrifugal chillers and 3 York screw chillers as the refrigeration system for the whole plant. The refrigeration system is responsible for providing cooling capacity, mainly for maintaining a stable temperature in the malt soaking workshop and germination workshop. The 6 refrigerators are equipped with 4 open cooling towers, and all condensation heat is directly discharged into the atmosphere.

[0051] The residual heat and waste heat that can be recovered by the project are calculated as shown in Table 3:

[0052] Table 3- Calculation table of waste heat that can be utilized in a malt factory

[0053]

[0054] The temperature of the wastewater in the soaking room is about 20℃, and the total discharge volume is about 1200m3 per day. 3 , about 2-3 times of concentrated discharge per day, the discharge time is not fixed. Later, it can be collected in the water collection tank. The wastewater temperature is 20℃, the heat pump recovery temperature difference is 7℃, and the heat is recovered at 13℃. The heat of the soaking wastewater is about 408.3kW; the temperature of the steam condensate returning to the boiler room after waste heat recovery is about 40℃, and the steam flow rate is 12t / h. This part of the hot water can be collected in the water tank for heat pump recycling. The heat pump recovery temperature difference is 20℃. After the heat is recovered, the 20℃ condensate returns to the biomass boiler, and the heat of the steam condensate is about 280kW; the cooling tower operates for 8 months from March to November each year, and is shut down for 3 months from December to February in winter. During the operation of the cooling tower from March to November, the load changes according to the outside temperature. The average operation of 2 units is calculated, and the heat dissipation of the cooling tower is about 7000kW.

[0055] In summary, the amount of waste heat that can be recovered by a malt factory is about 688.3 kW in winter (December-March) (when the chiller is shut down), and about 7688.3 kW in spring, summer and autumn (March-November) (when the chiller is running).

[0056] The main heat users of a malt factory are the winter air heating in the steeping room and germination room and the malt drying stage. Currently, all the commonly used heat comes from the steam supplied by the biomass boiler.

[0057] Steam is used in the malt soaking room and germination room mainly to heat the inlet air temperature in December, January and February to maintain the room temperature at 14-17℃.

[0058] The basic heat consumption process of the drying section: fresh air is mixed with part of the high-temperature return air, preheated by the exhaust air waste heat recovery device and the steam condensate waste heat recovery device, and then heated by steam to the required temperature of different process sections: about 45-60℃ in the early stage of drying, 25t / h of steam consumption, and lasting for about 15 hours; about 60-74℃ in the middle stage of drying, 10t / h of steam consumption, and lasting for about 6-8 hours; about 74-85℃ in the late stage of drying, 7t / h of steam consumption, and lasting for about 6-7 hours;

[0059] The two drying rooms operate alternately, recycling the waste heat of exhaust air and condensed water.

[0060] The plant consumes about 122,200 tons of steam throughout the year, of which the drying section consumes about 119,600 tons. The annual operating time is 330 days and the daily operating time is 21 hours, with an average steam consumption of about 17.3 t / h. The total steam consumption of the soaking and germination parts in the three winter months is about 2,600 t, with an average heat load of about 842.6 kW.

[0061] In winter, the waste heat is insufficient, and all 688.3kW of waste heat is used to generate hot water to replace part of the steam heat in the wheat soaking workshop and germination workshop. In spring, summer and autumn, the high-temperature hot water generated by the first heat pump and the waste heat from the cooling tower are used to produce low-pressure steam to replace part of the steam in the drying stage.

[0062] Through Figure 1 The transformation recovers the waste heat of the circulating water in the cooling tower of the refrigeration room (inlet and outlet water temperatures are 37°C / 32°C), and generates 70°C medium and high temperature hot water through the hot water heat pump 1. The 70°C hot water enters the energy storage tank for storage.

[0063] The soaking wheat wastewater transfers heat to the circulating water on the heat pump evaporator side through the plate exchanger. The steam condensate (about 40°C) is first recovered in the steam condensate water tank, and then mixed with the circulating water on the heat pump evaporator side and enters the heat pump. The hot water heat pump 2 generates 70°C medium and high temperature hot water, and the 70°C hot water enters the energy storage tank for storage.

[0064] In winter, part of the 70℃ hot water is used to heat the inlet air temperature in the malt soaking room and malt germination room, replacing the steam consumption in the malt soaking room and germination room.

[0065] Using part of the 70℃ medium and high temperature hot water as the heat source, a set of Freon micro-pressure steam heat pump units are connected in series to produce 0.1Mpa (gauge pressure) micro-pressure steam. The steam compressor uses part of the biomass boiler to produce 0.8Mpa / 1.0Mpa (gauge pressure) "high-pressure steam", and mixes 0.1Mpa micro-pressure steam to produce 0.3Mpa (gauge pressure) "medium-pressure steam" to provide to the drying section heat exchanger to heat the drying room intake air, thereby replacing part of the original 0.8MPa steam consumption in the heating drying section.

[0066] The energy storage tank has the ability to recover and store heat at the same time. It is used as a buffer to regulate the heat of hot water heat pumps and micro-pressure steam heat pumps, and also as a heat source to independently supply heat to energy consumption points.

[0067] Through the energy management system, various heat recovery points, energy supply points, and energy storage and release coupling systems are connected and integrated into the system. By predicting, judging and adjusting the production plan, production conditions and production needs, the start-up, shutdown, operation and adjustment processes of the high-temperature heat pump comprehensive energy application system can be realized in a timely and efficient manner.

[0068] The steam compressor used in this scheme uses advanced gas induced injection technology. The induced high-pressure steam pressure has a great influence on the scheme selection and configuration, especially on the induced injection amount of micro-low-pressure steam. When the high-pressure steam supply pressure is 0.8Mpa, the steam compressor mixing ratio is 4:1; when the high-pressure steam supply pressure is 1.0Mpa, the steam compressor mixing ratio is 2.5:1. The increase in high-pressure steam pressure means that the utilization rate of micro-pressure steam obtained by waste heat recovery is significantly improved.

[0069] The heat pump energy center is divided into functional areas and equipped with high-temperature heat pump units with different functions:

[0070] The hot water heat pump 1 utilizes the waste heat of the circulating water in the cooling tower to generate 70°C hot water.

[0071] The hot water heat pump 2 utilizes the waste heat of wheat soaking wastewater and steam condensate to generate 70°C hot water.

[0072] The micro-pressure steam heat pump uses the 70°C hot water generated by the above heat pump as a heat source to generate 0.1Mpa (gauge pressure) micro-pressure steam.

[0073] The heat pump host selection is shown in Table 4:

[0074]

[0075]

[0076] Table 4

[0077] When the maximum steam supply pressure of the boiler is 0.8Mpa, the steam compressor induction ratio is 4:1, and the 0.8Mpa biomass boiler can be used to produce 8.8t / h of steam and induce 2.2t / h of 0.1Mpa micro-pressure heat pump steam. That is, about 11 tons / hour of saturated steam of about 0.3-0.4MPa is supplied for wheat drying, meeting the heat demand for wheat drying.

[0078] In terms of energy recovery and supply-demand balance, energy storage tanks are configured to adjust the time and quantity difference between heat discharge and heat use in the production process, while taking into account the regulation of peak and valley electricity and supporting multi-temperature zone control; the effective volume of a single energy storage tank is about 300-400m 3 .

[0079] The price of purchased steam is 340 yuan / ton, the average electricity price is 0.7 yuan / kwh, the heat pump system for heating the soaking and germination parts in winter runs for 90 days, with an average daily operation time of 24 hours. The annual operation time of the micro-pressure steam heat pump system is 275 days (the heat source is insufficient in winter and the heat pump system does not produce steam), with an average daily operation time of 21 hours.

[0080] The heat pump system's micro-pressure steam output is 2.2t / h. The annual operating cost of the heat pump system is approximately RMB 3.961 million. The cost of purchasing steam with the same heat capacity is approximately RMB 5.2473 million, saving approximately RMB 1.2863 million.

[0081] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An energy recovery and reuse system for the malt industry, characterized in that: Including hot water heat pump 1, hot water heat pump 2, plate heat exchanger, energy storage tank, steam condensing water tank, micro-pressure steam heat pump and steam compressor; Hot water heat pump 1 is used to recover the waste heat of the circulating water in the cooling tower of the refrigeration room. The inlet and outlet water temperatures are 37°C and 32°C. On the one hand, 70°C hot water is generated by hot water heat pump 1, and the 70°C hot water enters the energy storage tank for storage. On the other hand, the circulating water in the energy storage tank is recovered. The plate heat exchanger is used to exchange the heat of the wheat soaking wastewater with the circulating water, mix it with the condensed water in the steam condensate tank and enter the hot water heat pump 2, and on the other hand, receives the circulating water on the evaporator side of the hot water heat pump; Hot water heat pump 2, the condensed water in the plate heat exchanger and the steam condensate tank enters the evaporator side of the hot water heat pump 2. On the one hand, 70℃ hot water is generated by the hot water heat pump 2, and the 70℃ hot water enters the energy storage tank for storage. On the other hand, the circulating water in the energy storage tank is recovered; Energy storage tank, one branch uses 70℃ hot water, combined with boiler room steam to supplement 70℃ hot water to the heat exchanger of the soaking and germination workshop, replacing the steam consumption of the boiler room of the soaking and germination workshop; the other branch enters the micro-pressure steam heat pump; the energy storage tank also has the function of recycling the circulating water used by the heat exchanger and micro-pressure steam heat pump of the soaking and germination workshop; The micro-pressure steam heat pump uses the 70℃ hot water in part of the energy storage tank to produce 0.1Mpa micro-pressure steam, which then enters the steam compressor, and on the other hand, it recovers the condensed water in the heat exchanger in the drying room; The steam compressor uses the 0.8-1.0Mpa steam from the boiler room on the one hand, and the 0.1Mpa micro-pressure steam from the micro-pressure steam heat pump on the other hand. After mixing, it produces 0.3Mpa medium-pressure steam, which is supplied to the heat exchanger in the drying room to heat the air inlet in the drying room, replacing the original 0.8Mpa steam consumption in the boiler room for heating the drying section. The steam condensate water tank is used to receive the steam used in the drying room heat exchanger, condense it, mix it with the circulating water of the plate heat exchanger and enter the hot water heat pump 2; on the other hand, it receives the circulating water on the evaporator side of the hot water heat pump 2 and recycles it to the boiler room.

2. The energy recovery and reuse system for the malt industry according to claim 1, characterized in that: The heat recovery capacity of the hot water heat pump 1 is 775 kW, the input power is 225 kW, and the heating capacity is 1000 kW.

3. The energy recovery and reuse system for the malt industry according to claim 1, characterized in that: The heat recovery capacity of the hot water heat pump 2 is 688.3 kW, the input power is 275 kW, and the heating capacity is 962.5 kW.

4. The energy recovery and reuse system for the malt industry according to claim 1, characterized in that: The heat recovery capacity of the micro-pressure steam heat pump is 1000 kW, the input power is 600 kW, and the heating capacity is 1600 kW.

5. The energy recovery and reuse system for the malt industry according to claim 1, characterized in that: The system also includes a control system for monitoring and controlling the operating status of various components in the system, including the pressure and temperature of steam, the temperature and flow of hot water, the collection and discharge of condensed water, etc., so as to achieve efficient recovery and utilization of energy.

6. The energy recovery and reuse system for the malt industry according to claim 1, characterized in that: When the high-pressure steam supply pressure of the steam compressor is 0.8Mpa, the steam compressor mixing ratio is 4:1; when the high-pressure steam supply pressure is 1.0Mpa, the steam compressor mixing ratio is 2.5:1.

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