Plant oil extraction plant waste heat recovery system

Abstract

This utility model discloses a waste heat recovery system for a vegetable oil leaching workshop. The wastewater pipe of the distribution tank is connected to the shell-side inlet of an energy-saving device; the shell-side outlet of the energy-saving device is connected to a wastewater cooking tank; the outlet of the wastewater cooking tank is connected to the tube-side inlet of the energy-saving device; the tube-side outlet of the energy-saving device is connected to a wastewater tank; the outlet of the wastewater tank is connected to the hot-side inlet of a wastewater heat exchanger; and the hot-side outlet of the wastewater heat exchanger is connected to a wastewater discharge pipe. In the mechanical heat pump, the tube-side outlet of the heat pump evaporator is connected to a medium-temperature water tank; the outlet of the medium-temperature water tank is connected to the cold-side inlet of the wastewater heat exchanger; and the cold-side outlet of the wastewater heat exchanger is connected to the tube-side inlet of the heat pump evaporator. In the mechanical heat pump, the tube-side outlet of the condenser is connected to a high-temperature water tank; the outlet of the high-temperature water tank is connected to the hot water inlet of the upper heat exchanger of the conditioning tower; and the hot water outlet of the upper heat exchanger of the conditioning tower is connected to the tube-side inlet of the condenser in the mechanical heat pump. This system, through multi-stage heat exchange and coupling with a mechanical heat pump, maximizes the recovery and utilization of heat from wastewater.

Description

Technical Field

[0001] This utility model relates to a heat recovery system, and more particularly to a waste heat recovery system for a vegetable oil extraction workshop, belonging to the field of high-efficiency energy-saving technology. Background Technology

[0002] Vegetable oil extraction involves two workshops: a pretreatment workshop and a leaching workshop. The leaching workshop uses n-hexane as a solvent, where vegetable oil dissolves to form a mixed oil with a concentration of 25-40%. The remaining solid phase after extraction is a wet meal with a solvent content of 25-35%. Both the liquid and solid phases exiting the leaching unit need to be sent to a solvent recovery section to reclaim the solvent.

[0003] The mixed oil is desolventized using an evaporator, which includes a first evaporator and a second evaporator. The mixed oil from the second evaporator has a concentration of 95-97%, and then enters a stripping tower. The stripping tower uses direct steam to remove the remaining solvent from the mixed oil, and finally enters a vacuum condenser. In the vacuum condenser, the direct steam is condensed into water, and finally enters a wastewater cooking tank to be discharged as wastewater.

[0004] The wet soybean meal desolventizing process uses a vertical steam desolventizer, which includes a pre-desolventizing layer, a mixed desolventizing layer, and a direct steam layer. Direct steam is introduced from the bottom of the direct steam layer, with a portion entering the steam phase of the desolventizer and a portion entering and exiting the soybean meal. The steam phase from the desolventizer is then condensed sequentially in the first evaporator, the economizer, and the DT condenser. Finally, the aqueous phase is discharged as wastewater from the wastewater cooking tank. The moisture entering the soybean meal is carried out by hot air in the drying and cooling machine. The humid hot air enters the economizer system, where the water vapor is finally condensed and discharged as wastewater.

[0005] Currently, wastewater from the digester enters a wastewater heat exchanger to exchange heat with the cold water entering the digester before being discharged at a temperature of 55℃-65℃. Wastewater from the DC energy-saving system is completely unused, with a discharge temperature of 50-80℃. The wastewater from both the digester and the DC energy-saving system eventually converges in a water seal tank at a temperature of 60-65℃, and is then pumped to a wastewater treatment plant.

[0006] Currently, the wastewater from the leaching workshop has two main drawbacks: firstly, the heat in the wastewater is not fully utilized, resulting in high discharge temperatures and energy waste; secondly, the temperature entering the wastewater treatment plant is too high, causing the bacteria in the wastewater treatment plant to be killed, which seriously affects the normal operation of the wastewater treatment plant. Utility Model Content

[0007] 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.

[0008] In view of the problems existing in the above and / or prior art, this utility model is proposed.

[0009] The purpose of this invention is to overcome the problems existing in the prior art and provide a waste heat recovery system for vegetable oil extraction workshops. This system can recover heat from wastewater to the maximum extent, save steam consumption in the entire pressing workshop, reduce the temperature of wastewater discharged from the extraction workshop, prevent bacteria from being killed in the wastewater treatment workshop, and improve the efficiency of the wastewater treatment workshop.

[0010] To solve the above technical problems, this utility model provides a waste heat recovery system for a vegetable oil leaching workshop, including a water distribution tank and a wastewater pipe. The outlet of the wastewater distribution tank and the wastewater pipe are connected to the shell-side inlet of an energy-saving device. The shell-side outlet of the energy-saving device is connected to the inlet of a wastewater cooking tank. A direct steam heating pipe is provided at the bottom of the wastewater cooking tank. A vapor phase pipe of the cooking tank is connected to the top of the wastewater cooking tank. The outlet of the wastewater cooking tank is connected to the tube-side inlet of the energy-saving device. The tube-side outlet of the energy-saving device is connected to the inlet of the wastewater tank. The outlet of the wastewater tank is connected to the hot-side inlet of the wastewater heat exchanger via a wastewater pump. The hot-side outlet of the wastewater heat exchanger is connected to a wastewater discharge pipe. In the mechanical heat pump, the tube-side outlet of the heat pump evaporator is connected to the inlet of the medium-temperature water tank, the outlet of the medium-temperature water tank is connected to the cold-side inlet of the wastewater heat exchanger through the medium-temperature water pump, and the cold-side outlet of the wastewater heat exchanger is connected to the tube-side inlet of the heat pump evaporator. The tube-side outlet of the condenser in the mechanical heat pump is connected to the inlet of the high-temperature water tank. The outlet of the high-temperature water tank is connected to the hot water inlet of the upper heat exchanger of the conditioning tower via a high-temperature water pump. The hot water outlet of the upper heat exchanger of the conditioning tower is connected to the tube-side inlet of the condenser in the mechanical heat pump.

[0011] Furthermore, the outlet of the first-level exhaust pipe of the drying cooler is connected to the air inlet of the lower side wall of the waste heat collector, and the condensate outlet of the lower side wall of the waste heat collector is connected to the inlet of the wastewater tank; the circulating water outlet at the bottom of the waste heat collector is connected to the hot water inlet of the top heat exchanger in the conditioning tower through a waste heat circulation pump, and the hot water outlet of the top heat exchanger in the conditioning tower is connected to the spray pipe inlet of the waste heat collector.

[0012] Furthermore, the waste heat collector adopts direct heat exchange, and its inner cavity is provided with upper and lower packing sections, with spray pipes respectively provided above the two packing sections.

[0013] Furthermore, the top gas phase outlet of the waste heat trap is vented to the atmosphere through the trap's exhaust pipe.

[0014] Compared with the prior art, the advantages or beneficial effects of this utility model include at least the following: 1. This system fully utilizes the heat from the hot water and wastewater collected in the first layer of the drying and cooling machine in the leaching workshop. The hot water collected in the first layer of the drying and cooling machine is directly used to heat soybeans in the conditioning tower, and the wastewater is used to heat soft water. The heated soft water is sent to the heat pump unit to finally produce medium- and high-temperature hot water. The produced medium- and high-temperature hot water is sent to the pretreatment conditioning tower to continue heating the soybeans in the conditioning tower, thus reducing the steam consumption in the oil processing process. 2. This system reduces the discharge temperature of wastewater from the leaching workshop, protects the microbial strains in the wastewater treatment workshop, and ensures the stable operation of the entire wastewater treatment workshop; 3. Using this technical solution, 10 kg of steam can be saved per ton of soybeans. Based on a steam price of 250 yuan / ton, a soybean crushing workshop with an output of 6,000 tons / day can save 15,000 yuan in production costs per day. Assuming 320 days of operation per year, the annual production cost savings can reach 4.8 million yuan. Attached Figure Description

[0015] 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 in the vegetable oil extraction workshop of this utility model; Attached reference numerals: T1. Wastewater tank; T2. Medium-temperature water tank; T3. High-temperature water tank; T4. Wastewater cooking tank; E1. Wastewater heat exchanger; E2. Eco-friendly device; E3. Waste heat trap; P1. Wastewater pump; P2. Medium-temperature water pump; P3. High-temperature water pump; P4. Waste heat circulation pump; HP. Mechanical heat pump; VSC. Conditioning tower; G1. Wastewater pipe of water distribution tank; G2. Wastewater discharge pipe; G3. Steam pipe; G4. Vapor phase pipe of cooking tank; G5. First-floor exhaust pipe of drying and cooling machine; G6. Exhaust pipe of collector. Detailed Implementation

[0016] 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.

[0017] 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.

[0018] 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.

[0019] like Figure 1 As shown, the waste heat recovery system for the vegetable oil leaching workshop of this utility model includes a wastewater tank T1, a medium-temperature water tank T2, a high-temperature water tank T3, a wastewater cooking tank T4, a wastewater heat exchanger E1, an energy-saving device E2, a waste heat collector E3, a mechanical heat pump HP, and a conditioning tower VSC. In the leaching workshop, the solvent-containing wastewater generated by the mixed oil desolventizing unit enters the water distribution tank for separation. The solvent separated from the water distribution tank returns to the leaching tank for circulation. The wastewater discharged from the water distribution tank is discharged through the wastewater pipe G1. The outlet of the wastewater pipe G1 is connected to the shell-side inlet of the energy-saving device E2, and the shell-side outlet of the energy-saving device E2 is connected to the inlet of the wastewater cooking tank T4. The outlet of the steam pipe G3 is connected to the steam injection perforated pipe at the bottom of the wastewater cooking tank T4 for direct steam heating. The top of the wastewater digester T4 is connected to the vapor phase pipe G4 of the digester. The outlet of the wastewater digester T4 is connected to the tube inlet of the energy-saving device E2, and the tube outlet of the energy-saving device E2 is connected to the inlet of the wastewater tank T1.

[0020] The outlet of the first-floor exhaust duct G5 of the drying cooler is connected to the air inlet on the lower side wall of the waste heat trap E3. The condensate outlet on the lower side wall of the waste heat trap E3 is connected to the inlet of the wastewater tank T1. The waste heat trap E3 adopts direct heat exchange, and its inner cavity is equipped with upper and lower packing sections, with spray pipes above each section. The circulating water outlet at the bottom of the waste heat trap E3 is connected to the inlet of the waste heat circulation pump P4. The outlet of the waste heat circulation pump P4 is connected to the hot water inlet of the top heat exchanger in the conditioning tower VSC. The hot water outlet of the top heat exchanger in the conditioning tower VSC is connected to the spray pipe inlet of the waste heat trap E3. The top gas phase outlet of the waste heat trap E3 is vented to the atmosphere through the trap exhaust pipe G6.

[0021] The outlet of wastewater tank T1 is connected to the inlet of wastewater pump P1, the outlet of wastewater pump P1 is connected to the hot side inlet of wastewater heat exchanger E1, and the hot side outlet of wastewater heat exchanger E1 is connected to the sewage treatment workshop through wastewater discharge pipe G2.

[0022] The HP mechanical heat pump is equipped with a heat pump evaporator and a condenser, as well as a medium-temperature water tank T2 and a high-temperature water tank T3. The tube-side outlet of the heat pump evaporator is connected to the inlet of the medium-temperature water tank T2, the outlet of the medium-temperature water tank T2 is connected to the inlet of the medium-temperature water pump P2, the outlet of the medium-temperature water pump P2 is connected to the cold-side inlet of the wastewater heat exchanger E1, and the cold-side outlet of the wastewater heat exchanger E1 is connected to the tube-side inlet of the heat pump evaporator in the HP mechanical heat pump.

[0023] In the HP mechanical heat pump, the tube-side outlet of the condenser is connected to the inlet of the high-temperature water tank T3, the outlet of the high-temperature water tank T3 is connected to the inlet of the high-temperature water pump P3, the outlet of the high-temperature water pump P3 is connected to the hot water inlet of the upper heat exchanger in the conditioning tower VSC, and the hot water outlet of the upper heat exchanger in the conditioning tower VSC is connected to the tube-side inlet of the HP mechanical heat pump.

[0024] 42°C wastewater from wastewater pipe G1 in the water distribution tank enters the shell side of the economizer E2. The drainage from the shell side of economizer E2 enters the wastewater cooking tank T4, where it is heated by steam from steam pipe G3 to evaporate the solvent. The evaporated gas phase enters the tail gas condenser for condensation through the gas phase pipe G4 of the cooking tank.

[0025] Wastewater at 100℃ discharged from wastewater cooking tank T4 enters the tube side of economizer E2, and the effluent from the tube side of economizer E2 enters wastewater tank T1. Hot air from the first-stage exhaust duct G5 of the dryer-cooler enters waste heat trap E3. Hot water at 55℃ is sprayed from above the packing of waste heat trap E3, coming into countercurrent contact with the first-stage gas phase of the dryer-cooler, absorbing heat from the gas phase, raising the hot water temperature to 65℃. The 65℃ hot water enters waste heat circulation pump P4, and after being pressurized by waste heat circulation pump P4, it enters the first stage of conditioning tower VSC to preheat the soybeans that have just entered. After heat exchange, the hot water temperature drops to 55℃ and returns to waste heat trap E3 for spraying. Water vapor in the first-stage gas phase of the dryer-cooler is condensed in waste heat trap E3, and the condensate enters wastewater tank T1 for collection.

[0026] The wastewater in wastewater tank T1 is at a temperature of 65℃. It is pumped by wastewater pump P1 to the hot side of wastewater heat exchanger E1. The outlet temperature of the hot side of wastewater heat exchanger E1 drops to 45℃ and is discharged to the sewage treatment workshop through wastewater discharge pipe G2.

[0027] The soft water in the medium-temperature water tank T2 is 35°C. It is pumped by the medium-temperature water pump P2 to the cold side of the wastewater heat exchanger E1. After being heated to 45°C, it enters the evaporation side of the mechanical heat pump HP to provide heat for the evaporation of the working fluid in the heat pump evaporator. After heat exchange, it is cooled to 35°C and returns to the medium-temperature water tank T2 for circulation.

[0028] The water in high-temperature tank T3 is at a temperature of 90°C. It is pumped by high-temperature water pump P3 to the upper part of the conditioning tower VSC to heat the preheated soybeans. The high-temperature water is then cooled to 80°C and enters the condenser of the mechanical heat pump HP. After being heated to 90°C in the condenser, the hot water re-enters high-temperature tank T3 for circulation.

[0029] 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 waste heat recovery system for a vegetable oil leaching workshop, comprising a water distribution tank and wastewater pipe (G1), characterized in that, The outlet of the wastewater pipe (G1) of the water distribution tank is connected to the shell-side inlet of the energy-saving device (E2). The shell-side outlet of the energy-saving device (E2) is connected to the inlet of the wastewater cooking tank (T4). The bottom of the wastewater cooking tank (T4) is equipped with a direct steam heating pipe. The top of the wastewater cooking tank (T4) is connected to the vapor phase pipe (G4) of the cooking tank. The outlet of the wastewater cooking tank (T4) is connected to the tube-side inlet of the energy-saving device (E2). The tube-side outlet of the energy-saving device (E2) is connected to the inlet of the wastewater tank (T1). The outlet of the wastewater tank (T1) is connected to the hot-side inlet of the wastewater heat exchanger (E1) through the wastewater pump (P1). The hot-side outlet of the wastewater heat exchanger (E1) is connected to the wastewater discharge pipe (G2). In the mechanical heat pump (HP), the tube-side outlet of the heat pump evaporator is connected to the inlet of the medium-temperature water tank (T2), the outlet of the medium-temperature water tank (T2) is connected to the cold-side inlet of the wastewater heat exchanger (E1) through the medium-temperature water pump (P2), and the cold-side outlet of the wastewater heat exchanger (E1) is connected to the tube-side inlet of the heat pump evaporator. The tube-side outlet of the condenser in the mechanical heat pump (HP) is connected to the inlet of the high-temperature water tank (T3). The outlet of the high-temperature water tank (T3) is connected to the hot water inlet of the upper heat exchanger of the conditioning tower (VSC) via the high-temperature water pump (P3). The hot water outlet of the upper heat exchanger of the conditioning tower (VSC) is connected to the tube-side inlet of the condenser in the mechanical heat pump (HP).

2. The waste heat recovery system for vegetable oil extraction workshop according to claim 1, characterized in that: The outlet of the first-level exhaust duct (G5) of the drying cooler is connected to the air inlet on the lower side wall of the waste heat collector (E3). The condensate outlet on the lower side wall of the waste heat collector (E3) is connected to the inlet of the wastewater tank (T1). The circulating water outlet at the bottom of the waste heat collector (E3) is connected to the hot water inlet of the top heat exchanger in the conditioning tower (VSC) via a waste heat circulation pump (P4). The hot water outlet of the top heat exchanger in the conditioning tower (VSC) is connected to the spray pipe inlet of the waste heat collector (E3).

3. The waste heat recovery system for vegetable oil extraction workshop according to claim 2, characterized in that: The waste heat collector (E3) adopts direct heat exchange, and its inner cavity is provided with upper and lower packing sections, with spray pipes respectively above the two packing sections.

4. The waste heat recovery system for vegetable oil extraction workshop according to claim 2 or 3, characterized in that: The top gas phase outlet of the waste heat trap (E3) is vented to the atmosphere through the trap exhaust pipe (G6).

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