Hot meal heat recovery system of evapo-separated machine

Abstract

The utility model discloses an evapo-separated machine hot meal heat recovery system which is characterized in that an evapo-separated machine is stacked above a drying cooler, an outlet of an air blower is connected with a hot air inlet of an air exhaust layer of the evapo-separated machine through a cold side of an air-air heat exchanger, and a hot air outlet of the air exhaust layer is connected with an air inlet of a spray catcher; a top exhaust port of the spray catcher is connected with a shell pass lower inlet of the falling-film evaporator through the induced draft fan, and a shell pass upper outlet of the falling-film evaporator is connected with the hot side of the air-air heat exchanger through the hot side of the air-air heat exchanger; a cold side inlet of the air-air heat exchanger is communicated with the atmosphere, a cold side outlet of the air-air heat exchanger is connected with hot air inlets of a second drying layer and a third drying layer of the drying cooler through a drying fan, and a hot air outlet of the first drying layer of the drying cooler is connected with an air inlet of the first-layer cyclone dust collector. And a top exhaust port of the first-layer cyclone dust collector is connected with a hot side inlet of the air-air heat exchanger. The system efficiently recovers high-grade heat of the hot meal, so that steam and production cost of soybean processing are saved.

Description

Technical Field

[0001] This utility model relates to a heat recovery system, and more particularly to a heat recovery system for hot meal from a steam desalination machine, belonging to the field of waste heat utilization technology. Background Technology

[0002] After pretreatment, oilseeds can be extracted with hexane using an extraction device called an extractor. There are many types of extractors, such as the E-type extractor, box chain extractor, annular extractor, rotary extractor, and drag chain extractor. The liquid phase from the extractor, i.e., the concentrated mixed oil, enters the evaporation system for solvent recovery, ultimately yielding crude oil. The solid phase from the extractor, i.e., the wet meal, is conveyed by a wet meal scraper into a descaling machine for solvent removal. The wet meal contains 20-35% solvent. It first undergoes pre-delamination under indirect steam to remove approximately 30% of the solvent. Then, in the mixed delamination layer, indirect and direct steam are used to further remove the remaining solvent, ensuring that the residual solvent in the hot meal is below 300 ppm. The meal temperature after pre-delamination is typically close to the boiling point of hexane, around 67°C. When it enters the mixed delamination layer and comes into countercurrent contact with water vapor from the direct steam layer, the water vapor condenses due to the large heat transfer temperature difference, increasing the meal temperature and moisture content. The hot meal exiting the direct steam layer has a temperature of 105-110℃, a moisture content of 18-19%, and carries a large amount of heat.

[0003] Currently, the main methods for heat recovery from hot meal produced by steam desalination machines are as follows:

[0004] Method 1: Chinese utility model patent CN 205090774U discloses a heat recovery system for a drying cooler, which uses a water trap for heat recovery. The collected hot water is then used to heat the cold air in the drying cooler or to heat the soybeans in the pretreatment conditioning tower. This technical solution does not recover heat sufficiently, but it can heat the cold air to about 65°C, saving approximately 8 kg of water vapor per ton of soybeans.

[0005] Method Two: Chinese utility model patent CN 205090785U discloses a waste heat recovery system for a drying and cooling machine. This system uses a plate heat exchanger for heat recovery, with the initial hot air from the drying and cooling machine on the hot side and the incoming cold air on the cold side. This technical solution does not fully recover heat, but it can heat the cold air to approximately 70°C, saving about 10 kg of water vapor per ton of soybeans.

[0006] Method 3: Chinese utility model patent CN 215810075U discloses a DC hot air waste heat recovery system. This system uses a falling film evaporator to heat soft water and generate low-pressure steam. The water flows through the tube side, while the first layer of hot air from the drying and cooling machine flows through the shell side. The falling film evaporator operates under vacuum, generated by a steam jet pump powered by high-pressure direct steam from the evaporator. This method can generate a vacuum of approximately -50 kPa. The hot air after passing through the falling film evaporator then exchanges heat with the soft water and the cold air from the drying and cooling machine. Under the actual steam flow rate required by the evaporator, this technical solution can only achieve a vacuum of approximately -50 kPa. At this point, the corresponding water evaporation temperature is 81°C, resulting in a small temperature difference between the water and the first layer of hot air from the drying and cooling machine. The actual logarithmic heat transfer temperature is only 5-6°C. The falling film evaporator can save approximately 6-8 kg of steam per ton of soybeans, and the subsequent soft water heater and air-cooled heat exchanger can save approximately 8 kg of steam per ton of soybeans, resulting in a total steam saving of 15 kg.

[0007] Method 4: Chinese utility model patent CN 220083595U discloses a DC hot air waste heat recovery system. This system uses a falling film evaporator to heat soft water to generate low-pressure steam. The low-pressure steam is then compressed by a centrifugal mechanical compressor and a steam jet pump. The compressed steam is used as the direct steam for the desiccant. In this solution, all flash steam enters the mechanical compressor, resulting in a high workload for the compressor and excessively high power consumption for the entire energy-saving system. Furthermore, the large size and power of the compressor also affect operational stability and increase maintenance costs. Utility Model Content

[0008] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, and such simplifications or omissions should not be construed as limiting the scope of the present invention.

[0009] In view of the problems existing in the above and / or prior art, this utility model is proposed.

[0010] The purpose of this invention is to overcome the problems of high power consumption and insufficient heat recovery in the existing technology of hot meal heat energy recovery, and to provide a heat recovery system for hot meal in a steam desalination machine. Before the hot meal enters the drying and cooling machine, it efficiently recovers high-grade heat, thereby saving steam costs and production costs in soybean processing.

[0011] To solve the above technical problems, this utility model provides a heat recovery system for hot meal from a steam degasser, including a drying and cooling machine. A steam degasser is stacked above the drying and cooling machine. An extraction layer is located below the direct steam heating layer of the steam degasser. The outlet of a blower is connected to the hot air inlet of the extraction layer of the steam degasser via the cold side of an air-air heat exchanger. The hot air outlet of the extraction layer is connected to the air inlet of a spray trap. The top exhaust port of the spray trap is connected to the lower shell inlet of a falling film evaporator via an induced draft fan. The upper outlet of the shell side is connected to the hot side inlet of the air-to-air heat exchanger via the hot side of the air-to-air heat exchanger, and the hot side outlet of the air-to-air heat exchanger is open to the atmosphere; the cold side inlet of the air-to-air heat exchanger is open to the atmosphere, and the cold side outlet of the air-to-air heat exchanger is connected to the hot air inlet of the second and third drying layers of the drying-cooling machine via a drying fan; the hot air outlet of the first drying layer of the drying-cooling machine is connected to the air inlet of the first layer of cyclone separator, and the top exhaust port of the first layer of cyclone separator is connected to the hot side inlet of the air-to-air heat exchanger.

[0012] As an improvement of this utility model, the bottom outlet of the tube side of the falling film evaporator is connected to the inlet of the first-stage flash tank, and the top secondary steam outlet of the first-stage flash tank is connected to the middle inlet of the steam jet pump; the main inlet of the steam jet pump is connected to the power steam pipe, the outlet of the steam jet pump is connected to the tube side inlet of the steam heater, the shell side inlet of the steam heater is connected to the heating steam pipe, and the shell side outlet of the steam heater is connected to the condensate collection pipe; the tube side outlet of the steam heater is connected to the steam inlet of the direct steam heating layer of the evaporator.

[0013] As a further improvement of this utility model, the bottom outlet of the primary flash tank is connected to the inlet of the secondary flash tank, the bottom outlet of the secondary flash tank is connected to the inlet of the falling film circulation pump, and the outlet of the falling film circulation pump is connected to the upper inlet of the tube side of the falling film evaporator.

[0014] As a further improvement of this utility model, the top secondary steam outlet of the secondary flash tank is connected to the inlet of the high-speed steam compressor, and the outlet of the high-speed steam compressor is also connected to the middle inlet of the steam jet pump.

[0015] Compared with the prior art, this utility model has achieved the following beneficial effects: 1. An extraction layer is added, and a separate air heat exchanger and fan are configured for the extraction layer, which can more accurately control the air volume and increase the temperature of the air entering the extraction layer, thus facilitating the improvement of the quality of the hot air entering the falling film evaporator; the hot air coming out of the first drying layer of the drying cooler passes through a cyclone separator and then enters the air heat exchanger in front of the drying fan for heat exchange before being discharged; a fan is added between the spray trap and the falling film evaporator to reduce the pressure of the connecting layer and prevent air from backflowing into the direct vapor layer, greatly reducing safety risks;

[0016] 2. Add another secondary flash tank below the flash tank supporting the falling film evaporator. The top of the secondary flash tank is connected to a mechanical compressor. The flash steam from the primary flash tank does not enter the steam compressor. The gas phase at the outlet of the mechanical compressor and the gas phase at the outlet of the primary flash tank are merged and then enter the steam jet pump. This enables more efficient heat recovery from the desolventizer, and the power of the mechanical compressor is reduced by more than 50%, significantly saving power consumption and electricity costs.

[0017] 3. The present utility model can save 28 kg of steam per ton of soybeans and 1 kWh of power consumption per ton of soybeans. Given a steam price of 250 yuan / ton and an electricity price of 0.7 yuan / kWh, a soybean pressing workshop with a daily output of 6,000 tons can save 46,200 yuan in production costs per day. Calculated based on 320 days of annual operation, it can save 14.78 million yuan in production costs annually. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] To more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the following drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings. The drawings are only for reference and explanation, and are not used to limit the present utility model. Among them:

[0019] Figure 1 It is a flowchart of the heat recovery system for hot meal in the desolventizer of the present utility model;

[0020] In the figure: T1. Spray trap; T2. Primary flash tank; T3. Secondary flash tank;

[0021] F1. Drying fan; F2. Blower; F3. Induced draft fan;

[0022] E1. Falling film evaporator; E2. Steam superheater; E3. DC air-air heat exchanger; E4. Exhaust layer air-air heat exchanger;

[0023] P1. Spray trap pump; P2. Falling film circulation pump;

[0024] V1. High-speed steam compressor; V2. Steam jet pump;

[0025] C1. First layer cyclone;

[0026] G1. Air inlet; G2. Condensate outlet; G3. Overflow port; G4. Make-up water port; G5. Condensate outlet; G6. Make-up water pipe; G7. Power steam pipe; G8. Heating steam pipe; G9. Condensate collection pipe; G10. Tail gas discharge port. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] In the following description of this utility model, the terms "upper", "lower", "front", "rear", "left", "right", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this utility model and simplifying the description, and do not mean that the device must have a specific orientation.

[0028] To make the technical means, creative features, achieved objectives and effects of this utility model easier to understand, the present utility model will be further described below with reference to specific illustrations. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0030] like Figure 1 As shown, the heat recovery system for hot meal from the steaming and desiccant of this utility model includes a steaming and desiccant drying and cooling machine, commonly known as DTDC. In the DTDC, the steaming and desiccant is stacked on top of the drying and cooling machine. The steaming and desiccant includes a direct steam heating layer DT1 and an air extraction layer DT2 from top to bottom. The drying and cooling machine includes a first drying layer DC1, a second drying layer DC2 and a third drying layer DC3 from top to bottom.

[0031] The inlet of blower F2 is open to the atmosphere, the outlet of blower F2 is connected to the cold side inlet of air heat exchanger E4, the cold side outlet of air heat exchanger E4 is connected to the hot air inlet of the extraction layer DT2 of the desiccant, the hot air outlet of the extraction layer DT2 is connected to the air inlet of spray trap T1, the bottom drain outlet of spray trap T1 is connected to the inlet of spray trap pump P1, the outlet of spray trap pump P1 is connected to the top spray outlet of spray trap T1, and the side wall of spray trap T1 is provided with overflow outlet G3 and water inlet G4.

[0032] The top exhaust port of the spray trap T1 is connected to the inlet of the induced draft fan F3. The outlet of the induced draft fan F3 is connected to the lower shell-side inlet of the falling film evaporator E1. The upper shell-side outlet of the falling film evaporator E1 is connected to the hot-side inlet of the air-to-air heat exchanger E4. The hot-side outlet of the air-to-air heat exchanger E4 is connected to the hot-side inlet of the air-to-air heat exchanger E3. The hot-side outlet of the air-to-air heat exchanger E3 is connected to the atmosphere through the exhaust port G10.

[0033] The cold side inlet of the air-to-air heat exchanger E3 is open to the atmosphere, the cold side outlet of the air-to-air heat exchanger E3 is connected to the inlet of the drying fan F1, the outlet of the drying fan F1 is connected to the hot air inlets of the second drying layer DC2 and the third drying layer DC3, the hot air outlet of the first drying layer DC1 is connected to the air inlet of the first layer cyclone separator C1, and the top exhaust port of the first layer cyclone separator C1 is also connected to the hot side inlet of the air-to-air heat exchanger E3.

[0034] The bottom outlet of the tube side of the falling film evaporator E1 is connected to the inlet of the first-stage flash tank T2, and the top secondary steam outlet of the first-stage flash tank T2 is connected to the middle inlet of the steam jet pump V2; the bottom outlet of the first-stage flash tank T2 is connected to the inlet of the second-stage flash tank T3, the bottom outlet of the second-stage flash tank T3 is connected to the inlet of the falling film circulation pump P2, and the outlet of the falling film circulation pump P2 is connected to the upper inlet of the tube side of the falling film evaporator E1.

[0035] The lower part of the secondary flash tank T3 is connected to a water supply pipe G6, and a water supply valve is installed on the water supply pipe G6. The opening and closing of the water supply valve is controlled by the liquid level of the secondary flash tank T3.

[0036] The top secondary steam outlet of the secondary flash tank T3 is connected to the inlet of the high-speed steam compressor V1, and the outlet of the high-speed steam compressor V1 is also connected to the intermediate inlet of the steam jet pump V2. The main inlet of the steam jet pump V2 is connected to the power steam pipe G7, the outlet of the steam jet pump V2 is connected to the tube-side inlet of the steam heater E2, the shell-side inlet of the steam heater E2 is connected to the heating steam pipe G8, and the shell-side outlet of the steam heater E2 is connected to the condensate collection pipe G9 to discharge condensate. The tube-side outlet of the steam heater E2 is connected to the steam inlet of the direct steam heating layer DT1 of the desiccant.

[0037] The hot meal exiting the direct steam heating layer DT1 of the evaporator has a moisture content of 18-19% and enters the lower extraction layer DT2. Under the suction of blower F2, natural air enters the cold side of the air-air heat exchanger E4 through air inlet G1, is heated, and enters the extraction layer DT2 of the evaporator. The hot air exiting the extraction layer DT2 reaches a temperature of 95℃ and a relative humidity of 75-80%, then enters the spray collector T1, where it is circulated and sprayed with water from the spray collector pump P1 for washing. The spray collector T1 also collects dust from the hot air in the first drying layer DC1 of the dryer-cooler, reducing the dust content in the hot air and lowering the risk of scaling in the falling film evaporator. The side wall of the spray collector T1 is equipped with an overflow port G3 and a water inlet G4.

[0038] Cleaned hot air, after washing, is sent by induced draft fan F3 to the lower shell side of falling film evaporator E1, where it exchanges heat with the circulating water in the tube side, performing the first recovery of waste heat from the hot air. The hot air discharged from the upper shell side of falling film evaporator E1 is cooled to 70°C and enters the hot side of air-to-air heat exchanger E4 to heat fresh air, performing a second recovery of waste heat. After this second recovery, the hot air merges with the outlet hot air from the first-layer cyclone separator C1 and enters the hot side inlet of air-to-air heat exchanger E3. Air-to-air heat exchanger E4 has a condensate outlet G2 at its bottom for easy condensate drainage during shutdown. Falling film evaporator E1 has a condensate outlet G5 at its bottom shell side for timely condensate drainage.

[0039] The heated hot water discharged from the bottom of the tube side of the falling film evaporator E1 enters the first-stage flash tank T2 for collection and flash evaporation. The hot water from the first-stage flash tank T2 flows by gravity into the second-stage flash tank T3. The hot water discharged from the bottom of the second-stage flash tank T3 is drawn out by the falling film circulation pump P2 and sent back to the top of the tube side of the falling film evaporator E1 for circulation heating.

[0040] The secondary flash tank T3 is replenished with water through the water supply pipe G6, and the opening and closing of the water supply valve on the water supply pipe G6 is controlled by the liquid level of the secondary flash tank T3.

[0041] The secondary steam exiting from the top of the primary flash tank T2 has a temperature of 81℃ and a pressure of 50 kPa; the secondary steam exiting from the secondary flash tank T3 has a temperature of 69℃ and is extracted by the high-speed steam compressor V1 (10000-30000 rpm). Under the suction action of the high-speed steam compressor V1, the absolute pressure at the bottom of the secondary flash tank T3 can be reduced to 30 kPa, greatly improving the vacuum level. After being compressed by the high-speed steam compressor V1, the secondary steam temperature rises to 81℃ and the absolute pressure rises to 50 kPa. It is then combined with the secondary steam from the primary flash tank T2 and enters the suction port of the steam jet pump V2. Steam from the power steam pipe G7 enters the main inlet of the steam jet pump V2. The temperature of the mixed steam discharged from the steam jet pump V2 rises to 114℃ and the absolute pressure rises to 160 kPa before entering the tube side of the steam heater E2. The live steam from the heating steam pipe G8 further heats the mixed steam, raising its temperature to 120℃, and it enters the direct steam heating layer DT1 at the bottom of the desiccant for direct heating and drying of the hot meal. The condensate from the shell side of the steam heater E2 is discharged through the condensate collection pipe G9.

[0042] The two-stage flash evaporation process eliminates the need for secondary steam from the outlet of the first-stage flash tank T2 to enter the high-speed steam compressor V1, reducing the load on V1 by more than 50%. After flash evaporation, the hot water temperature drops from 81℃ to 69℃, and is then evenly sprayed from the top into the falling film evaporator E1, increasing the heat transfer temperature difference between the hot air and the hot water and lowering the hot air temperature at the outlet of the falling film evaporator E1.

[0043] Hot air from the outlet of falling film evaporator E1 is introduced into the hot side of the exhaust heat exchanger E4 to heat the cold air from the outlet of blower F2. Then, it enters the hot side of the DC air heat exchanger E3 to heat the cold air in the DC drying layer, further recovering heat. This process raises the temperature of the cold air from 25°C to 70°C. The hot side of the DC air heat exchanger E3 is then discharged through exhaust port G10. These waste heat recovery measures allow this system to recover 23-30 kg of steam per ton of soybeans, increasing the recovery rate by 50%-100% compared to traditional waste heat recovery systems, resulting in significant economic value.

[0044] The above description is merely a preferred embodiment of the present utility model, showing and describing the basic principles, main features, and advantages of the present utility model. It is not intended to limit the scope of patent protection of the present utility model. Those skilled in the art should understand that the present utility model is not limited to the above embodiments. In addition to the above embodiments, the present utility model may have other implementations without departing from the spirit and scope of the present utility model. Various changes and improvements to the present utility model are also possible. All technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present utility model. The scope of protection claimed by the present utility model is defined by the appended claims and their equivalents. Technical features not described in the present utility model can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A heat recovery system for steam-dehydrator meal, comprising a drying and cooling machine, wherein a steam-dehydrator is stacked above the drying and cooling machine, and an extraction layer is provided below the direct steam heating layer of the steam-dehydrator, characterized in that: The blower outlet is connected to the hot air inlet of the extraction layer of the evaporator via the cold side of the air-air heat exchanger. The hot air outlet of the extraction layer is connected to the air inlet of the spray trap. The top exhaust port of the spray trap is connected to the lower shell inlet of the falling film evaporator via an induced draft fan. The upper shell outlet of the falling film evaporator is connected to the hot side inlet of the air-air heat exchanger via the hot side. The hot side outlet of the air-air heat exchanger is open to the atmosphere. The cold side inlet of the air-air heat exchanger is open to the atmosphere. The cold side outlet of the air-air heat exchanger is connected to the hot air inlets of the second and third drying layers of the drying cooler via a drying fan. The hot air outlet of the first drying layer of the drying cooler is connected to the air inlet of the first layer of cyclone separator. The top exhaust port of the first layer of cyclone separator is connected to the hot side inlet of the air-air heat exchanger.

2. The heat recovery system for steaming and desiccant meal according to claim 1, characterized in that: The bottom outlet of the falling film evaporator is connected to the inlet of the first-stage flash tank, and the top secondary steam outlet of the first-stage flash tank is connected to the middle inlet of the steam jet pump. The main inlet of the steam jet pump is connected to the power steam pipe, the outlet of the steam jet pump is connected to the tube-side inlet of the steam heater, the shell-side inlet of the steam heater is connected to the heating steam pipe, and the shell-side outlet of the steam heater is connected to the condensate collection pipe. The tube-side outlet of the steam heater is connected to the steam inlet of the direct steam heating layer of the desiccant.

3. The heat recovery system for steaming and desiccant meal according to claim 2, characterized in that: The bottom outlet of the primary flash tank is connected to the inlet of the secondary flash tank, the bottom outlet of the secondary flash tank is connected to the inlet of the falling film circulation pump, and the outlet of the falling film circulation pump is connected to the upper inlet of the tube side of the falling film evaporator.

4. The heat recovery system for steaming and desiccant meal according to claim 3, characterized in that: The secondary steam outlet at the top of the secondary flash tank is connected to the inlet of the high-speed steam compressor, and the outlet of the high-speed steam compressor is also connected to the intermediate inlet of the steam jet pump.

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