Multi-effect evaporation system for wastewater of grease leaching workshop

Abstract

The utility model discloses a grease leaching workshop wastewater multi-effect evaporation system which is characterized in that an outlet of a wastewater buffer tank is connected with an inlet of a feeding safety filter through a wastewater feeding pump, and an outlet of the feeding safety filter is connected with a top inlet of a first-effect falling film evaporator; bottom wastewater outlets of the first-effect falling film evaporator and the first-effect flash separator are connected with a second-effect wastewater circulating pipe through a wastewater transfer pump, and a circulating water outlet of the second-effect flash separator is connected with a tube pass water inlet of a second-effect wastewater evaporator through a wastewater circulating pump and the second-effect wastewater circulating pipe; a tube pass water outlet of the second-effect wastewater evaporator is connected with a circulating water inlet of the second-effect flash separator, and a wastewater outlet in the bottom of the second-effect flash separator is connected with the DC unit; a flash steam outlet in the top of the first-effect flash separator is connected with a shell pass air inlet of the second-effect wastewater evaporator, and a shell pass condensate outlet of the second-effect wastewater evaporator is connected with the drain tank. The system can realize real zero discharge of wastewater, reduces steam consumption and water consumption of the water cooling tower, and improves the steam water return rate of a leaching workshop.

Description

Technical Field

[0001] The utility model relates to an evaporation system, in particular to a multi-effect evaporation system for waste water in a grease leaching workshop, belonging to the technical field of evaporation equipment. Background Art

[0002] Traditional oil extraction plants generate a certain amount of wastewater during production. This wastewater primarily originates from processes using direct steam, including vertical degassing machines, cooking tanks, stripping towers, desorption towers, and steam jet pumps. This wastewater contains small amounts of meal, oil, and n-hexane, making it considered low-concentration wastewater. This wastewater is discharged into the extraction plant's water seal tank and subsequently into a sewage treatment plant, where it is treated using biochemical methods or other novel technologies. This essentially fails to address the wastewater discharge issue within the extraction plant, and its input and operating costs are high, increasing the plant's production costs.

[0003] Traditional zero-wastewater discharge technology uses saturated steam to heat wastewater from the leaching workshop. Flash steam generated from the superheated wastewater is used as direct steam for the degassing unit. The concentrated wastewater is then returned to the degassing unit and added to the meal. The concentrated wastewater primarily consists of meal powder and oil, and adding it to the meal does not affect product quality. This technology is feasible, but it does increase steam consumption by 15-20 kg / t of raw material.

[0004] Some foreign countries with large energy resources can accept the increase in steam consumption. What they demand is to be able to completely treat the wastewater generated by the leaching workshop process, achieve true zero emissions, and eliminate sewage treatment plants or reduce the operation of sewage treatment plants.

[0005] Currently, only a small number of domestic oil and fat plants are equipped with traditional zero wastewater discharge systems, and these are rarely operated. This is because the amount of wastewater generated by the extraction workshop exceeds the direct steam demand of the degassing unit, resulting in incomplete wastewater treatment. Furthermore, the installation of energy-saving and environmentally friendly equipment, such as liquid ring vacuum pumps and exhaust gas capture towers, further increases wastewater volume. Furthermore, increased steam consumption is also a contributing factor to oil plants' reluctance to achieve zero wastewater discharge.

[0006] Patent application number CN 201873545U discloses a wastewater flash tank for a zero-discharge system for oil and fat wastewater. This tank is used in the oil and fat extraction process to convert wastewater discharged from the wastewater digester into steam for evaporation and stripping of the mixed oil. The concentrated fluid is then returned to the mixed meal, eliminating wastewater discharge during the extraction process. However, this technical solution has two drawbacks: First, the wastewater flash steam has low quality and low heat exchange efficiency, and can only be used for indirect heating of the mixed oil, not for stripping, which affects the oil quality. Second, this concept does not achieve zero wastewater discharge because the amount of wastewater flash steam is far greater than the amount of steam required for evaporation of the mixed oil. Therefore, only a small amount of wastewater can be evaporated, and the condensate from the wastewater flash steam is still wastewater, so some wastewater will still be discharged from the workshop. Utility Model Content

[0007] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and utility model title of this application, and such simplifications or omissions shall not be used to limit the scope of the present invention.

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

[0009] The purpose of this utility model is to overcome the problems existing in the prior art and provide a multi-effect evaporation system for wastewater in a grease leaching workshop, which can increase the wastewater treatment capacity, achieve true zero wastewater discharge, reduce steam consumption, reduce water consumption in cooling towers, and improve the steam return rate of the leaching workshop, with important energy-saving and environmental protection benefits.

[0010] In order to solve the above technical problems, the utility model provides a multi-effect evaporation system for wastewater in a grease leaching workshop, comprising a wastewater feed pipe, the outlet of the wastewater feed pipe being connected to the inlet of a wastewater buffer tank, the outlet of the wastewater buffer tank being connected to the inlet of a wastewater feed pump, the outlet pipe of the wastewater feed pump being connected to the inlet of a feed safety filter, the outlet of the feed safety filter being connected to the top inlet of a single-effect falling film evaporator, the lower part of the single-effect falling film evaporator being connected to a single-effect flash separator through a connecting pipe,

[0011] The bottom wastewater outlet of the first-effect falling film evaporator and the first-effect flash separator is connected to the inlet of the wastewater transfer pump, the outlet of the wastewater transfer pump is connected to the second-effect wastewater circulation pipe, the circulating water outlet of the second-effect flash separator is connected to the inlet of the wastewater circulation pump, the outlet of the wastewater circulation pump is connected to the tube-side water inlet of the second-effect wastewater evaporator through the second-effect wastewater circulation pipe, the tube-side water outlet of the second-effect wastewater evaporator is connected to the circulating water inlet of the second-effect flash separator, and the bottom wastewater outlet of the second-effect flash separator is connected to the DC liquid injection port of the DTDC equipment through the concentrated wastewater pipe;

[0012] The flash steam outlet at the top of the first-effect flash separator is connected to the shell-side air inlet of the second-effect wastewater evaporator, and the shell-side condensate outlet of the second-effect wastewater evaporator is connected to the inlet of the drain tank.

[0013] As an improvement of the present invention, the raw steam pipe is connected to the shell side inlet of the single-effect falling film evaporator, the shell side outlet of the single-effect falling film evaporator is connected to the high-temperature condensate tank, and the outlet of the high-temperature condensate tank is connected to the boiler water tank through a soft water pump.

[0014] As a further improvement of the present invention, the outlet of the drain tank is connected to the inlet of the condensate tank, the outlet of the condensate tank is connected to the inlet of the discharge safety filter through a condensate pump, the outlet of the discharge safety filter is connected to the hot side water inlet of the air heater, the hot side water outlet of the air heater is connected to the water inlet of the spiral plate heat exchanger, and the water outlet of the spiral plate heat exchanger is connected to the water supply port of the cooling tower through a second-effect condensate cooling pipe.

[0015] As a further improvement of the present invention, the flash steam outlet at the top of the second-effect flash separator is connected to the tube-side steam inlet of the steam superheater, the shell-side steam inlet of the steam superheater is connected to the superheated heater steam pipe, and the shell-side condensate outlet of the steam superheater is connected to the high-temperature condensate tank; the tube-side steam outlet of the steam superheater is connected to the DT direct steam jacket of the DTDC equipment through the superheated steam pipe.

[0016] Compared with the existing technology, the utility model has achieved the following beneficial effects: 1. The leaching plant adopts multi-effect evaporation to achieve zero wastewater discharge, and uses the flash steam from the first effect to heat the wastewater from the second effect, which can reduce the increase in steam consumption by 30%.

[0017] 2. Increased wastewater treatment capacity, achieving true zero wastewater discharge. The total wastewater volume of the leaching workshop is divided into two, so that the flash steam generated by the second effect is less than the direct steam volume of the evaporation, avoiding overheating and overpressure of the evaporation gas phase and ensuring stable production.

[0018] 3. Increase the return rate of steam in the leaching workshop to 70%, saving boiler operating costs, which is of great significance for energy conservation, emission reduction and economic benefits.

[0019] 4. The flash steam condensate of the first effect is cooled and sent to the cooling tower as make-up water to reduce the water consumption of the leaching workshop; the flash steam condensate temperature of the first effect is greater than 95℃, which is used to preheat the DC cold air of the steam stripping machine to reduce the steam consumption of the workshop. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work. The drawings are only provided for reference and explanation, and are not intended to limit the present invention. Among them:

[0021] Figure 1 This is a flow chart of the utility model's multi-effect evaporation system for wastewater from a grease extraction workshop;

[0022] Figure: 1. Wastewater buffer tank; 2. Feed safety filter; 3. First-effect falling film evaporator; 4. First-effect flash separator; 5. Second-effect wastewater evaporator; 6. Second-effect flash separator; 7. Steam superheater; 8. Drain tank; 9. Condensate tank; 10. Discharge safety filter; 11. Air heater; 12. Spiral plate heat exchanger; 13. Cooling tower; 14. High-temperature condensate tank.

[0023] P1. Wastewater feed pump; P2. Wastewater transfer pump; P3. Wastewater circulation pump; P4. Condensate pump;

[0024] G1. Wastewater feed pipe; G2. First-effect falling film evaporator inlet pipe; G3. Wastewater transfer pipe; G4. Second-effect wastewater circulation pipe; G5. Concentrated wastewater pipe; G6. Raw steam pipe; G7. First-effect flash steam outlet pipe; G8. Superheat heater steam pipe; G9. Superheated steam pipe; G10. Second-effect condensate pipe; G11. Second-effect condensate heat exchange pipe; G12. Second-effect condensate cooling pipe. DETAILED DESCRIPTION

[0025] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below with reference to specific figures. Obviously, the embodiments described are only a part of the present invention, not all of the embodiments.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] like Figure 1As shown, the multi-effect evaporation system for wastewater in a grease extraction workshop of the present invention includes a wastewater buffer tank 1, a feed safety filter 2, a first-effect falling film evaporator 3, a first-effect flash separator 4, a second-effect wastewater evaporator 5, a second-effect flash separator 6, a steam superheater 7, a drain tank 8, a condensate tank 9, a discharge safety filter 10, an air heater 11 and a spiral plate heat exchanger 12.

[0028] The outlet of the wastewater feed pipe G1 is connected to the inlet of the wastewater buffer tank 1, the outlet of the wastewater buffer tank 1 is connected to the inlet of the wastewater feed pump P1, the outlet of the wastewater feed pump P1 is connected to the inlet of the feed safety filter 2 through a pipeline, the outlet of the feed safety filter 2 is connected to the top inlet of the single-effect falling film evaporator 3 through the single-effect falling film evaporator inlet pipe G2, the bottom wastewater outlet of the single-effect falling film evaporator 3 and the single-effect flash separator 4 is connected to the inlet of the wastewater transfer pump P2, and the wastewater transfer pump P2 is connected to the inlet of the wastewater transfer pump P2. The outlet is connected to the second-effect wastewater circulation pipe G4 via the wastewater transfer pipe G3. The circulating water outlet of the second-effect flash separator 6 is connected to the inlet of the wastewater circulation pump P3. The outlet of the wastewater circulation pump P3 is connected to the tube-side water inlet of the second-effect wastewater evaporator 5 via the second-effect wastewater circulation pipe G4. The tube-side water outlet of the second-effect wastewater evaporator 5 is connected to the circulating water inlet of the second-effect flash separator 6. The bottom wastewater outlet of the second-effect flash separator 6 is connected to the DC unit injection port of the DTDC equipment via the concentrated wastewater pipe G5. The upper part of the DTDC equipment is the DT unit for solvent evaporation, and the lower part is the DC unit for drying and cooling.

[0029] The raw steam pipe G6 is connected to the shell side inlet of the single-effect falling film evaporator 3, and the shell side outlet of the single-effect falling film evaporator 3 is connected to the high-temperature condensed water tank 14 through the condensed water collection pipe. The outlet of the high-temperature condensed water tank 14 is connected to the boiler water tank through a soft water pump.

[0030] The flash steam outlet at the top of the first-effect flash separator 4 is connected to the shell-side air inlet of the second-effect wastewater evaporator 5 through the first-effect flash steam outlet pipe G7, the shell-side condensate outlet of the second-effect wastewater evaporator 5 is connected to the inlet of the drain tank 8 through the second-effect condensate pipe G10, the outlet of the drain tank 8 is connected to the inlet of the condensate tank 9, the outlet of the condensate tank 9 is connected to the inlet of the condensate pump P4, the outlet of the condensate pump P4 is connected to the inlet of the discharge safety filter 10, the outlet of the discharge safety filter 10 is connected to the hot side water inlet of the air heater 11, the hot side water outlet of the air heater 11 is connected to the water inlet of the spiral plate heat exchanger 12 through the second-effect condensate heat exchange pipe G11, and the water outlet of the spiral plate heat exchanger 12 is connected to the water supply port of the cooling tower 13 through the second-effect condensate cooling pipe G12.

[0031] The flash steam outlet at the top of the second-effect flash separator 6 is connected to the tube-side steam inlet of the steam superheater 7. The shell-side steam inlet of the steam superheater 7 is connected to the superheater steam pipe G8. The shell-side condensate outlet of the steam superheater 7 is connected to the high-temperature condensate tank 14 through a condensate collection pipe. The tube-side steam outlet of the steam superheater 7 is connected to the DT direct steam jacket of the DTDC equipment through a superheated steam pipe G9.

[0032] The grease wastewater with a temperature of 80°C sent out by the wastewater feed pipe G1 enters the wastewater buffer tank 1 for buffering. The wastewater coming out of the wastewater buffer tank 1 is sent to the feed safety filter 2 for filtration through the wastewater feed pump P1 to remove some impurities; the wastewater coming out of the feed safety filter 2 is sent to the top of the single-effect falling film evaporator 3 through the single-effect falling film evaporator inlet pipe G2, and is evenly distributed to each tube array through the liquid distribution plate, heated to 143°C, and enters the single-effect flash separator 4 for flash separation; the single-effect falling film evaporator 3 and the single-effect flash separator The unflashed wastewater discharged from the bottom of the second-effect flash separator 4 is sent to the second-effect wastewater circulation pipe G4 via the wastewater transfer pump P2 and the wastewater transfer pipe G3; the wastewater discharged from the bottom of the second-effect flash separator 6 is sent to the tube side of the second-effect wastewater evaporator 5 via the wastewater circulation pump P3 and the second-effect wastewater circulation pipe G4, heated to 120°C, and then sent back to the second-effect flash separator 6 for flash separation; the concentrated wastewater at the bottom of the second-effect flash separator 6 is discharged through the concentrated wastewater pipe G5 to the material of the DC unit of the DTDC equipment for drying, accounting for about 3-5% of the total wastewater volume.

[0033] 10-bar saturated steam enters the shell side of the first-effect falling-film evaporator 3 via the raw steam pipe G6 as a heat source. 3-bar flash steam discharged from the top of the first-effect flash separator 4 is fed into the shell side of the second-effect wastewater evaporator 5 via the first-effect flash steam outlet pipe G7 as a heat source. 1-bar flash steam discharged from the top of the second-effect flash separator 6 is fed into the tube side of the steam superheater 7. After being heated and dehydrated by high-temperature saturated steam delivered by the hot heater steam pipe G8, it is then fed into the DT direct steam jacket of the DTDC equipment via the superheated steam pipe G9 for use as DT direct steam.

[0034] The condensate discharged from the shell side of the second-effect wastewater evaporator 5 enters the drain tank 8 through the second-effect condensate pipe G10, and the condensate discharged from the drain tank 8 enters the condensate tank 9. The condensate from the condensate tank 9 is sent to the discharge safety filter 10 for filtration through the condensate pump P4. After removing impurities, it enters the hot side of the air heater 11 to preheat the DC cold air; the condensate from the air heater 11 is sent to the spiral plate heat exchanger 12 for cooling through the second-effect condensate heat exchange pipe G11, and the temperature is reduced to less than 40°C. It is then sent to the cooling tower 13 through the second-effect condensate cooling pipe G12 as cooling tower makeup water.

[0035] The above description is only a preferred embodiment of the present invention, which shows and describes the basic principles, main features and advantages of the present invention, but does not limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. In addition to the above embodiments, the present invention may have other implementation methods without departing from the spirit and scope of the present invention. The present invention may also have various changes and improvements, and all technical solutions formed by equivalent replacement or equivalent transformation fall within the scope of protection required by the present invention. The scope of protection required by the present invention is defined by the attached claims and their equivalents. Technical features not described in the present invention can be achieved by or using existing technologies, and will not be described here.

Claims

1. A multi-effect evaporation system for wastewater from a grease extraction workshop, comprising a wastewater feed pipe, the outlet of which is connected to the inlet of a wastewater buffer tank, the outlet of which is connected to the inlet of a wastewater feed pump, characterized in that: The outlet pipe of the wastewater feed pump is connected to the inlet of the feed safety filter, the outlet of the feed safety filter is connected to the top inlet of the first-effect falling film evaporator, and the lower part of the first-effect falling film evaporator is connected to the first-effect flash separator through a connecting pipe; the bottom wastewater outlets of the first-effect falling film evaporator and the first-effect flash separator are connected to the inlet of the wastewater transfer pump, the outlet of the wastewater transfer pump is connected to the second-effect wastewater circulation pipe, the circulating water outlet of the second-effect flash separator is connected to the inlet of the wastewater circulation pump, the outlet of the wastewater circulation pump is connected to the tube-side water inlet of the second-effect wastewater evaporator through the second-effect wastewater circulation pipe, the tube-side water outlet of the second-effect wastewater evaporator is connected to the circulating water inlet of the second-effect flash separator, and the bottom wastewater outlet of the second-effect flash separator is connected to the DC liquid injection port of the DTDC equipment through the concentrated wastewater pipe; The flash steam outlet at the top of the first-effect flash separator is connected to the shell-side air inlet of the second-effect wastewater evaporator, and the shell-side condensate outlet of the second-effect wastewater evaporator is connected to the inlet of the drain tank.

2. The multi-effect evaporation system for wastewater from a grease extraction workshop according to claim 1, characterized in that: The raw steam pipe is connected to the shell side inlet of the first-effect falling film evaporator, the shell side outlet of the first-effect falling film evaporator is connected to the high-temperature condensed water tank, and the outlet of the high-temperature condensed water tank is connected to the boiler water tank through a soft water pump.

3. The multi-effect evaporation system for wastewater from a grease extraction workshop according to claim 1, characterized in that: The outlet of the drain tank is connected to the inlet of the condensate tank, the outlet of the condensate tank is connected to the inlet of the discharge safety filter through a condensate pump, the outlet of the discharge safety filter is connected to the hot side water inlet of the air heater, the hot side water outlet of the air heater is connected to the water inlet of the spiral plate heat exchanger, and the water outlet of the spiral plate heat exchanger is connected to the water supply port of the cooling tower through a second-effect condensate cooling pipe.

4. The multi-effect evaporation system for wastewater from a grease extraction workshop according to claim 2, characterized in that: The flash steam outlet at the top of the second-effect flash separator is connected to the tube-side steam inlet of the steam superheater, the shell-side steam inlet of the steam superheater is connected to the steam pipe of the superheated heater, and the shell-side condensate outlet of the steam superheater is connected to the high-temperature condensate tank; the tube-side steam outlet of the steam superheater is connected to the DT direct steam jacket of the DTDC equipment through the superheated steam pipe.

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