Waste heat recovery system for steaming and frying pans in oilseed pressing plants

Abstract

This utility model discloses a waste heat recovery system for the exhaust gas from a steaming and frying pan in an oil pressing plant. The steaming and frying pan's air outlet is connected to the air inlet of a water-air heat exchanger, the water-air heat exchanger's air outlet is connected to an exhaust gas fan, the exhaust gas fan's outlet is connected to the hot-side air inlet of the water-air heat exchanger, the water-air heat exchanger's hot-side air outlet is connected to the air inlet of a scrubbing tower, and the scrubbing tower's air outlet is open to the atmosphere. The water-air heat exchanger's cold-side air inlet is open to the atmosphere, and its cold-side air outlet is connected to the air inlet of the drying layer of a conditioning tower, which is also open to the atmosphere. The water-air heat exchanger's hot water outlet is connected to the heating layer inlet of the conditioning tower, the conditioning tower's heating layer outlet is connected to the cold-side water inlet of a plate heat exchanger, and the plate heat exchanger's cold-side water outlet is connected to a water storage tank. The water storage tank's outlet is connected to the water-air heat exchanger's hot water inlet via a hot water circulation pump. This system can reduce steam consumption during oil processing and minimize the impact on the surrounding atmospheric environment.

Description

Technical Field

[0001] This utility model relates to a low-grade heat source heat recovery system, and more particularly to a waste heat recovery system for the exhaust gas of a steaming and frying pan in an oil pressing plant, belonging to the field of high-efficiency energy-saving technology. Background Technology

[0002] In oilseed pressing plants, conditioning and steaming / roasting are the core processes of oil pretreatment, requiring a large amount of steam energy. These two processes account for over 95% of the total steam consumption in the entire oil pretreatment plant. Therefore, fully utilizing the waste heat generated during conditioning and steaming / roasting is of great significance in responding to the national call for energy conservation and emission reduction.

[0003] The conditioning tower is an important piece of equipment in the oil conditioning process. Its main function is to heat and soften the oil using indirect steam, causing the internal moisture of the oil to evaporate to the surface, thus giving the oil better plasticity. The conditioning tower heats the oil to a temperature rise of 40-50°C using indirect steam, removing 2-3% of the water, and then introduces hot air at 50-60°C to remove surface moisture from the oil.

[0004] The steaming and frying pan is the core equipment in the oilseed steaming and frying process. In oilseed pressing plants, it serves the dual function of physical conditioning and chemical modification, directly affecting the oil yield, crude oil quality, and subsequent processing efficiency. The steaming and frying pan uses steam to raise the oilseed temperature from 55-65℃ to 95-130℃, reducing the moisture content from 6-8% to ≤5%, thereby disrupting the oilseed cell structure and improving pressing efficiency. During the steaming and frying process, high-temperature exhaust gas containing dust and moisture is continuously generated. The exhaust gas temperature from the steaming and frying pan can reach over 95℃. Currently, most oilseed pressing plants directly vent this exhaust gas, resulting in a significant waste of low-grade waste heat resources and causing environmental thermal pollution.

[0005] Chinese utility model patent CN 222317812U discloses a "Low-Grade Heat Recovery System for Oilseed Pressing Plants," comprising a conditioning tower, a water-air heat exchanger, and a heat pump. This technical solution recovers heat from multiple low-grade heat sources in the oilseed pressing plant via a water-air heat exchanger, using it as a heat source on the evaporator side of the heat pump to heat the hot water entering the conditioning tower. The drawbacks of this technology are: complex process route, high equipment investment cost, and strong dependence on the heat pump. The stability of the heat pump is crucial in this process; if the heat pump fails, the entire energy-saving system will fail. Furthermore, the heat pump consumes a lot of electricity, increasing production and maintenance costs.

[0006] Chinese utility model patent CN 222635112U discloses a "waste heat recovery and utilization system for a drying and cooling machine," comprising a conditioning tower, a drying and cooling machine, and a wind-water heat exchanger. This technical solution recovers waste heat from the drying and cooling machine of an oilseed pressing plant through wind-air and wind-water heat exchangers, using it to heat the hot water entering the conditioning tower, and then directly discharges the waste gas at 57°C. The drawbacks are: currently, most oilseed pressing plants no longer use hot air for cooling in their drying and cooling machines, resulting in a significant decrease in the outlet air temperature of the drying and cooling machine, a substantial reduction in the heat exchanger's heat exchange efficiency, and a low return on investment; furthermore, the final exhaust gas temperature is still above 55°C, and there are no effective measures to capture dust particles in the exhaust gas, causing dust and heat pollution to the surrounding environment.

[0007] In summary, there is significant room for improvement in the comprehensive utilization of waste heat in oilseed pressing plants. On the one hand, low-grade waste heat generated in processes such as conditioning, steaming, roasting, and puffing / cooling is generally not effectively utilized due to factors such as low temperatures and complex recovery technologies; direct venting leads to waste of waste heat energy. On the other hand, while existing exhaust gas treatment devices can remove oil fumes and dust from waste gases, they focus only on pollution control and neglect heat recovery, failing to effectively address the fundamental problem of energy waste. Therefore, constructing an efficient waste heat recovery system has become a pressing technical challenge for the oilseed pressing industry. 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 existing in the prior art and provide a waste heat recovery system for the exhaust gas of the steaming and frying pan in an oil pressing plant. This system can fully recover the latent heat of water vapor in the exhaust gas, provide a high-quality heat source for the conditioning tower, reduce steam consumption during oil processing, and reduce the dust concentration in the exhaust gas, thereby reducing the impact on the surrounding atmospheric environment.

[0011] To solve the above technical problems, this utility model provides a waste heat recovery system for exhaust gas from a steaming and frying pan in an oil pressing plant. The system includes a steaming and frying pan, the air outlet of which is connected to the air inlet of a water-air heat exchanger, the air outlet of which is connected to the air inlet of an exhaust gas fan, the air outlet of which is connected to the hot-side air inlet of a wind-air heat exchanger, the hot-side air outlet of which is connected to the air inlet of a scrubbing tower, and the air outlet of the scrubbing tower is connected to the atmosphere through an exhaust pipe. The cold-side air inlet of the air-air heat exchanger is connected to the atmosphere through an air inlet pipe, and the cold-side air outlet of the air-air heat exchanger is connected to the air inlet of the drying layer of the conditioning tower. The air outlet of the drying layer of the conditioning tower is connected to the atmosphere through an air outlet pipe. The hot water outlet of the air-water heat exchanger is connected to the heating layer inlet of the conditioning tower, the heating layer outlet of the conditioning tower is connected to the cold side inlet of the plate heat exchanger, the cold side outlet of the plate heat exchanger is connected to the inlet of the water storage tank, and the outlet of the water storage tank is connected to the hot water inlet of the air-water heat exchanger through a hot water circulation pump.

[0012] As an improvement of this utility model, the hot-side oil inlet of the plate heat exchanger is connected to the high-temperature pressing crude oil pipe, and the hot-side oil outlet of the plate heat exchanger is connected to the medium-temperature pressing crude oil pipe.

[0013] As a further improvement of this utility model, the outlet of the washing tower is connected to the inlet of the washing tower spray pump, and the outlet of the washing tower spray pump is connected to the top spray pipe of the washing tower.

[0014] As a further improvement of this utility model, the bottom of the air-water heat exchanger is provided with a water tank, the outlet of the water tank is connected to the inlet of the air-water heat exchanger spray pump, and the outlet of the air-water heat exchanger spray pump is connected to the top spray pipe of the air-water heat exchanger and the air-wind heat exchanger.

[0015] As a further improvement of this utility model, the drain outlet at the bottom of the air heat exchanger is connected to the water tank, and the overflow outlet of the water tank is connected to the sewage pipe.

[0016] Compared to the prior art, the advantages or beneficial effects of the embodiments of this application include at least the following: 1. Adding a water-air heat exchanger after the exhaust gas outlet of the steaming and frying pan utilizes the heat from the exhaust gas to heat the hot water entering the conditioning tower, obtaining hot water at 75-85℃. This saves 25kg of fresh steam per ton of oil processed. 2. Adding an air-air heat exchanger before the air inlet of the drying layer of the conditioning tower utilizes the remaining heat from the steaming and frying pan exhaust gas after heating the hot water, heating the hot air entering the conditioning tower, obtaining fresh hot air at 50-60℃. This saves 5kg of fresh steam per ton of oil processed. 3. Utilizing the heat from the high-temperature crude oil pressed in the oil pressing plant to heat the hot water raises the water temperature by 5-8℃, saving 5kg of fresh steam per ton of oil processed. In total, these energy-saving methods can save approximately 35kg or more of steam per ton of oil processed.

[0017] 2. By utilizing the waste heat from the steaming and frying pan exhaust gas through air-water and air-air heat exchangers, and the cooling effect of the scrubbing tower, the final emission temperature of the steaming and frying pan exhaust gas is controlled below 50℃. Simultaneously, by recovering and utilizing the heat from the high-temperature pressing of crude oil through plate heat exchangers, the temperature of the crude oil is controlled below 70℃, which is conducive to storage. This significantly reduces the use of circulating cooling water; for every ton of raw material processed, the circulating cooling water consumption can be reduced by approximately 100~120 m³ / h, and electricity consumption can be saved by 0.05 kWh per ton of oilseed processed.

[0018] 3. The spray in the air-water heat exchanger, air-to-air heat exchanger, and scrubbing tower captures dust in the exhaust gas from the steaming and frying pan, reducing the dust particle content in the exhaust gas.

[0019] 4. Taking a 3000TPD oilseed pressing plant as an example: based on a fresh steam price of 250 yuan / ton and an industrial electricity price of 0.7 yuan / kWh, the daily cost savings are: 3000*(35 / 1000*250+0.05*0.7-0.25*0.7)=25,800 yuan. Assuming the plant processes for 300 days a year, the annual savings would be 7.74 million yuan. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The drawings are provided for reference and illustration only and are not intended to limit this utility model. Wherein: Figure 1 This is a flowchart of the waste heat recovery system for the exhaust gas from the steaming and frying pan in an oilseed pressing plant, as described in this utility model. In the diagram: 1. Steamer / fryer; 2. Conditioning tower; 3. Washing tower; E1. Water-cooled heat exchanger; E2. Plate heat exchanger; E3. Air-to-air heat exchanger; F1. Exhaust gas fan; T1. Water tank; T2. Water storage tank; P1. Spray pump for air-water heat exchanger; P2. Hot water circulation pump; P3. Spray pump for washing tower; L1. High-temperature pressing crude oil pipe; L2. Medium-temperature pressing crude oil pipe; G1. Scrubber exhaust pipe; G2. Air inlet pipe; G3. Conditioning tower exhaust pipe; G4. Sewage pipe. Detailed Implementation

[0021] 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.

[0022] 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.

[0023] 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.

[0024] like Figure 1 As shown, the waste heat recovery system for the exhaust gas from the steaming and frying pan in an oil pressing plant of this utility model includes a steaming and frying pan 1, a conditioning tower 2, a water-air heat exchanger E1, a plate heat exchanger E2, a wind-air heat exchanger E3, a water tank T1, a water storage tank T2, and a scrubbing tower 3. The air outlet of the steaming and frying pan 1 is connected to the air inlet of the water-air heat exchanger E1. The air outlet of the water-air heat exchanger E1 is connected to the air inlet of the exhaust gas fan F1. The air outlet of the exhaust gas fan F1 is connected to the hot-side air inlet of the wind-air heat exchanger E3. The hot-side air outlet of the wind-air heat exchanger E3 is connected to the air inlet of the scrubbing tower 3. The air outlet of the scrubbing tower 3 is connected to the atmosphere through an exhaust pipe G1. The water outlet of the scrubbing tower 3 is connected to the water inlet of the scrubbing tower spray pump P3, and the water outlet of the scrubbing tower spray pump P3 is connected to the top spray pipe of the scrubbing tower 3.

[0025] The cold side air inlet of the air-air heat exchanger E3 is connected to the atmosphere through the air inlet pipe G2. The cold side air outlet of the air-air heat exchanger E3 is connected to the air inlet of the drying layer of the conditioning tower 2. The conditioning tower 2 is provided with a feeding section, a heating layer, a drying layer and a discharge layer from top to bottom. The air outlet of the drying layer of the conditioning tower 2 is connected to the atmosphere through the air outlet pipe G3.

[0026] The hot water outlet of the air-water heat exchanger E1 is connected to the heating layer inlet of the conditioning tower 2. The heating layer outlet of the conditioning tower 2 is connected to the cold side inlet of the plate heat exchanger E2. The cold side outlet of the plate heat exchanger E2 is connected to the inlet of the water storage tank T2. The outlet of the water storage tank T2 is connected to the inlet of the hot water circulation pump P2. The outlet of the hot water circulation pump P2 is connected to the hot water inlet of the air-water heat exchanger E1. The hot side oil inlet of the plate heat exchanger E2 is connected to the high-temperature pressed crude oil pipe L1. The hot side oil outlet of the plate heat exchanger E2 is connected to the medium-temperature pressed crude oil pipe L2.

[0027] The bottom of the air-water heat exchanger E1 is equipped with a water tank T1, which contains a spray pump P1. The outlet of the water tank T1 is connected to the inlet of the spray pump P1, and the outlet of the spray pump P1 is connected to the spray pipes at the top of both the air-water heat exchanger E1 and the air-to-air heat exchanger E3. The drain outlet at the bottom of the air-to-air heat exchanger E3 is connected to the water tank T1, and the overflow outlet of the water tank T1 is connected to the sewage pipe G4.

[0028] Taking a 3000TPD rapeseed pressing plant as an example, the exhaust gas flow rate of the steaming and frying pan 1 is 20000 m³ / h, the temperature is 95~100℃, and the relative humidity is 85%. Under the suction of the exhaust gas fan F1, the exhaust gas from the steaming and frying pan 1 enters the water-air heat exchanger E1 and flows from top to bottom, exchanging heat with the hot water flowing from bottom to top in a counter-current manner. The exhaust gas from the outlet of the water-air heat exchanger E1 has a flow rate of 18000 m³ / h and a temperature reduced to 75℃. It is then introduced into the hot-side inlet of the air-air heat exchanger E3 via the exhaust gas fan F1. After heat exchange in the air-air heat exchanger E3, the exhaust gas temperature is 55℃. The exhaust gas from the hot-side outlet of the air-air heat exchanger E3 enters the scrubbing tower 3. The scrubbing tower 3 is equipped with a scrubbing tower spray pump P3, which collects dust particles and cools the exhaust gas from the steaming and frying pan entering the scrubbing tower 3. After cooling, the exhaust gas temperature is 45℃, and it is finally discharged into the atmosphere from the outlet of the scrubbing tower 3 through the scrubbing tower exhaust pipe G1.

[0029] The water-cooled heat exchanger E1 heats hot water at a flow rate of 80 m³ / h and a temperature of 62°C to 85°C. This 85°C hot water then goes to the heating layer of the conditioning tower 2 to heat the rapeseed, raising its temperature from 30°C to 55°C. After exchanging heat with the rapeseed in the conditioning tower 2, the hot water's temperature drops to 55°C and it exits from the outlet of the heating layer of the conditioning tower 2. It then enters the cold side of the plate heat exchanger E2 to exchange heat with rapeseed oil from the high-temperature pressing oil pipe L1 at a flow rate of 55 m³ / h and a temperature of 90°C. After the heat exchange, the hot water's temperature rises to 62°C and it enters the storage tank T2 for temporary storage. The rapeseed oil's temperature drops to 70°C and it exits through the hot side outlet of the plate heat exchanger E2 to the medium-temperature pressing oil pipe L2 for storage.

[0030] The outlet of spray pump P1 is split into two paths, spraying and capturing dust particles inside the air-water heat exchanger E1 and the air-to-air heat exchanger E3 respectively, reducing dust particles in the exhaust gas of the steaming and frying pan while capturing the gas phase. The condensate and dust particles captured by the air-to-air heat exchanger E3 are discharged from the condensate outlet of the air-to-air heat exchanger into the water tank T1, where they are combined with the condensate and dust particles captured by the air-water heat exchanger E1 and discharged into the sewage pipe G4 through the condensate outlet of the water tank T1.

[0031] The fresh air temperature is 30℃ and the air volume is 15000m³ / h when it enters the cold side air inlet of the air-air heat exchanger E3 through the air inlet pipe G2. After heat exchange in the air-air heat exchanger E3, the temperature of the fresh air rises to 55℃. Then it enters the drying layer air inlet of the conditioning tower 2, passes through the rapeseed material layer from bottom to top, takes away the moisture on the surface of the rapeseed, and is discharged through the conditioning tower outlet pipe G3 connected to the drying layer air outlet of the conditioning tower 2.

[0032] 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 system for recovering waste heat from the exhaust gases of a cooking kettle in an oil pressing plant, comprising a cooking kettle (1), characterized in that: The air outlet of the steaming and frying pan (1) is connected to the air inlet of the air-water heat exchanger (E1), the air outlet of the air-water heat exchanger (E1) is connected to the air inlet of the exhaust fan (F1), the air outlet of the exhaust fan (F1) is connected to the hot side air inlet of the air-air heat exchanger (E3), the hot side air outlet of the air-air heat exchanger (E3) is connected to the air inlet of the scrubbing tower (3), and the air outlet of the scrubbing tower (3) is connected to the atmosphere through the exhaust pipe (G1). The cold side air inlet of the air heat exchanger (E3) is connected to the atmosphere through the air inlet pipe (G2), and the cold side air outlet of the air heat exchanger (E3) is connected to the air inlet of the drying layer of the conditioning tower (2). The air outlet of the drying layer of the conditioning tower (2) is connected to the atmosphere through the air outlet pipe (G3). The hot water outlet of the air-water heat exchanger (E1) is connected to the heating layer inlet of the conditioning tower (2), the heating layer outlet of the conditioning tower (2) is connected to the cold side inlet of the plate heat exchanger (E2), the cold side outlet of the plate heat exchanger (E2) is connected to the inlet of the water storage tank (T2), and the outlet of the water storage tank (T2) is connected to the hot water inlet of the air-water heat exchanger (E1) through the hot water circulation pump (P2).

2. The oil mill expeller plant steam cooker exhaust waste heat recovery system of claim 1, wherein: The hot-side oil inlet of the plate heat exchanger (E2) is connected to the high-temperature pressing crude oil pipe (L1), and the hot-side oil outlet of the plate heat exchanger (E2) is connected to the medium-temperature pressing crude oil pipe (L2).

3. The oil mill expeller plant flue gas waste heat recovery system according to claim 1, characterized in that: The outlet of the washing tower (3) is connected to the inlet of the washing tower spray pump (P3), and the outlet of the washing tower spray pump (P3) is connected to the top spray pipe of the washing tower (3).

4. The waste heat recovery system for the exhaust gas from the steaming and frying pan of an oil pressing plant according to claim 1, 2, or 3, characterized in that: The bottom of the air-water heat exchanger (E1) is equipped with a water tank (T1), the outlet of the water tank (T1) is connected to the inlet of the air-water heat exchanger spray pump (P1), and the outlet of the air-water heat exchanger spray pump (P1) is connected to the top spray pipe of the air-water heat exchanger (E1) and the air-air heat exchanger (E3).

5. The oil mill expeller plant flue gas waste heat recovery system according to claim 4, characterized in that: The drain outlet at the bottom of the air-to-air heat exchanger (E3) is connected to the water tank (T1), and the overflow outlet of the water tank (T1) is connected to the sewage pipe (G4).

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