An energy recovery and reuse system for the malt industry

Abstract

This invention discloses an energy recovery and reuse system for the malt industry, comprising a first hot water heat pump, a second hot water heat pump, a plate heat exchanger, an energy storage tank, a steam condensate tank, a micro-pressure steam heat pump, and a steam compressor. This invention utilizes a modified heat pump system. A heat pump is a device that uses electrical energy to raise heat from a low temperature to a high temperature, offering advantages such as environmental friendliness, energy saving, economy, and convenience. In scenarios like malt factories where energy efficiency is crucial and both cooling and heating are required, the heat pump thermal energy system can flexibly adapt to different heating functions, achieving low-temperature waste heat recovery.

Description

Technical Field

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

[0002] The main energy consumption in malt production is steam. Malt manufacturing can be divided into five processes: cleaning, grading, soaking, germination, drying, and root removal. Of these processes, the main energy consumption involves soaking, germination, and drying. The primary heat sources are maintaining the winter temperature in the soaking and germination rooms, and the malt drying process itself. The refrigeration station in the malt factory mainly consists of centrifugal chillers and York screw chillers. The refrigeration system provides cooling capacity, primarily to maintain a stable temperature in the soaking and germination rooms. The chillers are equipped with open cooling towers, and all condensation heat is directly released into the atmosphere. Summary of the Invention

[0003] To address energy losses during malt production and enable energy recovery and reuse, this invention utilizes a modified heat pump system. A heat pump is a device that uses electrical energy to raise heat from a low temperature to a high temperature, offering advantages such as environmental friendliness, energy efficiency, economy, and convenience. In scenarios like malt factories where energy efficiency is crucial and both cooling and heating are required, the heat pump thermal energy system can flexibly adapt to different heating functions, achieving the recovery of low-temperature waste heat.

[0004] The purpose of this invention is to provide a high-temperature heat pump energy application system that recovers waste heat from the cooling tower circulating water in the refrigeration room and heat from the malting wastewater, uses a small amount of electricity to drive a high-temperature heat pump to generate medium- and high-temperature hot water, converts part of the hot water into low-pressure steam, and then mixes it with high-pressure steam to generate medium-pressure steam, which is then supplied to meet 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 includes a hot water heat pump I, a hot water heat pump II, a plate heat exchanger, an energy storage tank, a steam condensate tank, a micro-pressure steam heat pump, and a steam compressor.

[0007] Hot water heat pump one is used to recover waste heat from the cooling tower circulating water in the refrigeration room. The inlet and outlet water temperatures are 37℃ and 32℃, respectively. On the one hand, hot water heat pump one generates 70℃ hot water, which enters the energy storage tank for storage. On the other hand, it recovers the circulating water in the energy storage tank.

[0008] The plate heat exchanger serves two purposes: firstly, it exchanges heat from wheat soaking wastewater with circulating water, mixing it with condensate from the steam condensate tank before entering the hot water heat pump; secondly, it receives circulating water from the evaporator side of the hot water heat pump.

[0009] In the second hot water heat pump, the condensate from the plate heat exchanger and the steam condensate tank enters the evaporator side of the second hot water heat pump. On the one hand, the second hot water heat pump generates 70°C hot water, which enters the storage tank for storage. On the other hand, the circulating water in the storage tank is recycled.

[0010] The energy storage tank has one branch that uses 70°C hot water, combined with boiler room steam, to supplement the heat exchanger in the wheat germination workshop with 70°C hot water, replacing the boiler room's steam consumption in the wheat germination workshop; the other branch leads to a micro-pressure steam heat pump; the energy storage tank also has the function of recovering the circulating water used by the heat exchanger in the wheat germination workshop and the micro-pressure steam heat pump.

[0011] The low-pressure steam heat pump utilizes 70°C hot water from a portion of the storage tank to produce 0.1 MPa low-pressure steam, which then enters the steam compressor. On the other hand, it recovers the condensate from the heat exchanger in the drying room.

[0012] The steam compressor utilizes steam from the boiler room at 0.8-1.0 MPa on one hand, and micro-pressure steam from a micro-pressure steam heat pump at 0.1 MPa on the other. After mixing, it generates medium-pressure steam at 0.3 MPa, which is supplied to the heat exchanger in the drying room to heat the intake air, replacing part of the original 0.8 MPa steam consumption from the boiler room for heating the drying section.

[0013] The steam condensate tank serves two purposes: firstly, it receives steam used by the heat exchanger in the drying room, then condenses it and mixes it with the circulating water from the plate heat exchanger before entering the second hot water heat pump; secondly, it receives circulating water from the evaporator side of the second hot water heat pump and returns it to the boiler room.

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

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

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

[0017] Preferably, the system further includes a control system for monitoring and controlling the operating status of various components in the system, including steam pressure and temperature, hot water temperature and flow rate, condensate collection and discharge, etc., so as to achieve efficient energy recovery and utilization.

[0018] Preferably, when the high-pressure steam supply pressure 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 this invention include:

[0020] 1. Improved energy utilization efficiency by recovering waste heat resources, thus achieving the upgrading and warming of low-grade energy;

[0021] 2. It reduces energy consumption and dependence on traditional energy sources;

[0022] 3. It improves the system's flexibility and adaptability, enabling flexible adjustments based on different heating functions. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating the structure of the present invention. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection 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 I, a hot water heat pump II, 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 one is used to recover waste heat from the cooling tower circulating water in the refrigeration room. The inlet and outlet water temperatures are 37℃ and 32℃, respectively. On the one hand, hot water heat pump one generates 70℃ hot water, which enters the energy storage tank for storage. On the other hand, it recovers the circulating water in the energy storage tank.

[0027] The plate heat exchanger serves two purposes: firstly, it exchanges heat from wheat soaking wastewater with circulating water, mixing it with condensate from the steam condensate tank before entering the hot water heat pump; secondly, it receives circulating water from the evaporator side of the hot water heat pump.

[0028] In the second hot water heat pump, the condensate from the plate heat exchanger and the steam condensate tank enters the evaporator side of the second hot water heat pump. On the one hand, the second hot water heat pump generates 70°C hot water, which enters the storage tank for storage. On the other hand, the circulating water in the storage tank is recycled.

[0029] The energy storage tank has one branch that uses 70°C hot water, combined with boiler room steam, to supplement the heat exchanger in the wheat germination workshop with 70°C hot water, replacing the boiler room's steam consumption in the wheat germination workshop; the other branch leads to a micro-pressure steam heat pump; the energy storage tank also has the function of recovering the circulating water used by the heat exchanger in the wheat germination workshop and the micro-pressure steam heat pump.

[0030] The low-pressure steam heat pump utilizes 70°C hot water from a portion of the storage tank to produce 0.1 MPa low-pressure steam, which then enters the steam compressor. On the other hand, it recovers the condensate from the heat exchanger in the drying room.

[0031] The steam compressor utilizes steam from the boiler room at 0.8-1.0 MPa on one hand, and micro-pressure steam from a micro-pressure steam heat pump at 0.1 MPa on the other. After mixing, it generates medium-pressure steam at 0.3 MPa, which is supplied to the heat exchanger in the drying room to heat the intake air, replacing part of the original 0.8 MPa steam consumption from the boiler room for heating the drying section.

[0032] The steam condensate tank serves two purposes: firstly, it receives steam used by the heat exchanger in the drying room, then condenses it and mixes it with the circulating water from the plate heat exchanger before entering the second hot water heat pump; secondly, it receives circulating water from the evaporator side of the second hot water heat pump and returns it to the boiler room.

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

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

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

[0036] Preferably, the system further includes a control system for monitoring and controlling the operating status of various components in the system, including steam pressure and temperature, hot water temperature and flow rate, condensate collection and discharge, etc., so as to achieve efficient energy recovery and utilization.

[0037] Preferably, when the high-pressure steam supply pressure 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 certain malt company mainly engages in the research, development, production, and sales of malt. Its annual malt production is approximately 130,000 tons, with steam being the primary energy source, consuming approximately 130,000 tons of steam annually. Based on on-site investigation, the company's basic production situation is as follows:

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

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

[0042] The on-site waste heat resources are shown in Table 1 below:

[0043] Table 1 - Summary of Waste Heat in a Malt Factory

[0044]

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

[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) and the steam price is 340-360 yuan / ton. The main heat sources are the winter room temperature maintenance in the soaking and germination rooms and the malt drying, as shown in Table 2.

[0047] Table 2 - Summary of Heat Consumption at a Malt Factory

[0048]

[0049]

[0050] The workshop's refrigeration station is equipped with three Carrier centrifugal chillers and three York screw chillers as the plant's refrigeration system. This system provides cooling capacity, primarily to maintain stable temperatures in the wheat soaking and germination workshops. The six chillers are connected to four open cooling towers, and all condensation heat is directly released into the atmosphere.

[0051] The calculation of waste heat and residual heat that can be recovered by the project is shown in Table 3 below:

[0052] Table 3 - Calculation of Usable Waste Heat in a Malt Factory

[0053]

[0054] The wastewater from the wheat soaking room is at approximately 20°C, with a total daily discharge of about 1200 m³. 3 The wastewater is discharged approximately 2-3 times daily at irregular times. It can be collected in a collection tank. The wastewater temperature is estimated at 20℃, with a 7℃ temperature difference for heat pump recovery. After heat recovery, it is discharged at 13℃, with a heat output of approximately 408.3kW. The steam condensate, after waste heat recovery, returns to the boiler room at approximately 40℃, with a steam flow rate of 12t / h. This hot water can be collected in a tank for heat pump recycling. The heat pump recovery temperature difference is 20℃, and the 20℃ condensate is returned to the biomass boiler, with a heat output of approximately 280kW. The cooling tower operates for 8 months annually from March to November and is shut down for 3 months from December to February. During the March-November operating period, the load on the cooling tower varies depending on the outside temperature, averaging 2 units operating, with a total heat dissipation of approximately 7000kW.

[0055] In summary, the recoverable waste heat of a certain malt plant is approximately 688.3 kW in winter (December-March) (when the chiller unit is shut down) and approximately 7688.3 kW in spring, summer and autumn (March-November) (when the chiller unit is in operation).

[0056] The main heat sources used in a certain malt factory are the winter air intake heating in the soaking and germination rooms and the malt drying stage. Currently, all the commonly used heat comes from the steam supplied by the biomass boiler.

[0057] The steam used in the soaking and germination rooms is mainly used to heat the air intake temperature in December, January, and February, maintaining the room temperature at 14-17℃.

[0058] The basic heat usage process in the drying section: High-temperature return air from the fresh air mixing section is preheated by the exhaust waste heat recovery device and the steam condensate waste heat recovery device, and then heated by steam to the required temperature for different process stages: approximately 45-60℃ in the early stage of drying, with a steam consumption of 25t / h and a duration of approximately 15 hours; approximately 60-74℃ in the middle stage of drying, with a steam consumption of 10t / h and a duration of approximately 6-8 hours; and approximately 74-85℃ in the later stage of drying, with a steam consumption of 7t / h and a duration of approximately 6-7 hours.

[0059] The two drying rooms operate alternately, recycling the waste heat from exhaust air and condensate.

[0060] The plant consumes approximately 122,200 tons of steam annually, of which approximately 119,600 tons are used in the drying section. Assuming an annual operating time of 330 days and a daily operating time of 21 hours, the average steam consumption is approximately 17.3 t / h. The total steam consumption for the wheat soaking and germination sections during the three winter months is approximately 2,600 t, with an average heat load of approximately 842.6 kW.

[0061] In winter, due to insufficient waste heat, all 688.3kW of waste heat is used to generate hot water to replace some of the steam used in the wheat soaking and germination workshops. 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 some of the steam used in the drying stage.

[0062] After such Figure 1 The renovation recovers the waste heat from the circulating water of the cooling tower in the refrigeration room (inlet and outlet water temperatures 37℃ / 32℃), and generates 70℃ medium-high temperature hot water through hot water heat pump 1. The 70℃ hot water enters the energy storage tank for storage.

[0063] The wastewater from soaking wheat transfers heat to the circulating water on the evaporator side of the heat pump via a plate heat exchanger. The steam condensate (approximately 40°C) is first recovered in the steam condensate tank, and then mixed with the circulating water on the evaporator side of the heat pump before entering the heat pump. The hot water heat pump 2 generates medium-high temperature hot water at 70°C, which is then stored in the energy storage tank.

[0064] In winter, 70℃ hot water is used to heat the air intake temperature of the wheat soaking workshop and the malt germination workshop, replacing the amount of steam used in the wheat soaking and germination workshops.

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

[0066] The energy storage tank has both heat recovery and heat storage capabilities, serving as a buffer and regulator for the heat from hot water heat pumps and micro-pressure steam heat pumps, as well as an independent heat source that supplies heat to the energy consumption point.

[0067] By integrating various heat recovery points, energy supply points, and energy storage and release coupling systems into the energy management system, and by predicting, judging, and adjusting production plans, production conditions, and production demands, the system can achieve timely and efficient start-up, shutdown, operation, and adjustment of the high-temperature heat pump integrated energy application system.

[0068] The steam compressor used in this scheme employs advanced gas-induced ejection technology. The induced high-pressure steam pressure has a significant impact on the selection and configuration of the scheme, especially on the induced ejection amount of micro-low-pressure steam. When the high-pressure steam supply pressure 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. The increase in high-pressure steam pressure means a significant improvement in the utilization rate of micro-pressure steam obtained from waste heat recovery.

[0069] The heat pump energy center is functionally divided into zones with different high-temperature heat pump units for various functions:

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

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

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

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

[0074]

[0075]

[0076] Table 4

[0077] When the boiler's maximum steam supply pressure is 0.8 MPa, and the steam compressor induction ratio is 4:1, the 0.8 MPa biomass boiler can produce 8.8 t / h of steam, which in turn induces 2.2 t / h of steam from a 0.1 MPa micro-pressure heat pump. This provides approximately 11 tons / h of saturated steam at about 0.3-0.4 MPa for wheat drying, meeting the wheat drying heat requirements.

[0078] In terms of energy recovery and supply-demand balance, energy storage tanks are configured to regulate the time and quantity differences between heat exhaust and heat consumption in the production process, while also taking into account peak-valley electricity regulation and supporting multi-temperature zone control; the effective volume of a single energy storage tank is approximately 300-400 m³. 3 .

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

[0080] The heat pump system has a micro-pressure steam output of 2.2 t / h and an annual operating cost of approximately RMB 3.961 million. The cost of purchasing steam for the same amount of heat is approximately RMB 5.2473 million, resulting in a cost saving of approximately RMB 1.2863 million.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An energy recycling system for the malting industry, characterized in that, Including hot water heat pump I, hot water heat pump II, plate heat exchanger, energy storage tank, steam condensate tank, micro-pressure steam heat pump and steam compressor; Hot water heat pump one is used to recover waste heat from the cooling tower circulating water in the refrigeration room. The inlet and outlet water temperatures are 37℃ and 32℃, respectively. On the one hand, hot water heat pump one generates 70℃ hot water, which enters the energy storage tank for storage. On the other hand, it recovers the circulating water in the energy storage tank. The plate heat exchanger serves two purposes: firstly, it exchanges heat from the wheat soaking wastewater with circulating water, mixing it with the condensate in the steam condensate tank before entering the second hot water heat pump; secondly, it receives circulating water from the evaporator side of the second hot water heat pump. In the second hot water heat pump, the condensate from the plate heat exchanger and the steam condensate tank enters the evaporator side of the second hot water heat pump. On the one hand, the second hot water heat pump generates 70°C hot water, which enters the storage tank for storage. On the other hand, the circulating water in the storage tank is recycled. The energy storage tank has one branch that uses 70°C hot water, combined with boiler room steam, to supplement the heat exchangers in the wheat soaking and germination workshops with 70°C hot water, replacing the steam consumption of the boiler room in the wheat soaking and germination workshops; the other branch goes into the micro-pressure steam heat pump; the energy storage tank also recovers the circulating water used by the heat exchangers in the wheat soaking and germination workshops and the micro-pressure steam heat pump. The low-pressure steam heat pump utilizes 70°C hot water from a portion of the storage tank to produce 0.1 MPa low-pressure steam, which then enters the steam compressor. On the other hand, it also recovers condensate from the heat exchanger in the drying room. The steam compressor utilizes 0.8-1.0 MPa steam from the boiler room on one hand, and 0.1 MPa micro-pressure steam from the micro-pressure steam heat pump on the other hand. After mixing, it generates 0.3 MPa medium-pressure steam, which is supplied to the heat exchanger in the drying room to heat the air intake of the drying room, replacing part of the original 0.8 MPa steam consumption from the boiler room for heating the air intake of the drying room. The steam condensate tank serves two purposes: firstly, it receives steam used by the heat exchanger in the drying room, then condenses it and mixes it with the circulating water from the plate heat exchanger before entering the second hot water heat pump; secondly, it receives circulating water from the evaporator side of the second hot water heat pump and returns it to the boiler room.

2. An energy recovery and reuse system for the malting industry as claimed in claim 1, characterised in that, The heat recovery capacity of the hot water heat pump is 775 kW, the input power is 225 kW, and the heating capacity is 1000 kW.

3. A system for energy recovery and reuse in the malting industry according to claim 1, characterised in that, The second hot water heat pump has a heat recovery capacity of 688.3 kW, an input power of 275 kW, and a heating capacity of 962.5 kW.

4. The energy recovery and reuse system for the malting industry of claim 1, wherein, The micro-pressure steam heat pump has a heat recovery capacity of 1000 kW, an input power of 600 kW, and a heating capacity of 1600 kW.

5. A system for energy recovery and reuse in the malting industry according to claim 1, wherein, The system also includes a control system for monitoring and controlling the operating status of various components in the system, including steam pressure and temperature, hot water temperature and flow rate, and condensate collection and discharge, so as to achieve efficient energy recovery and utilization.

6. A system for energy recovery and reuse in the malting industry according to claim 1, wherein, When the high-pressure steam supply pressure 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.

Images