DTDC hot-air waste heat recovery system

Abstract

A DTDC hot-air waste heat recovery system, wherein a DC cyclone (1) is connected to a first centrifugal fan (2) by means of a pipe; the first centrifugal fan (2) is connected to the bottom end of a shell side of a falling film evaporator (3); the top end of the shell side of the falling film evaporator (3) is then connected to the bottom end of a shell side of a miscella evaporator (7) by means of a pipe; the top end of the shell side of the miscella evaporator (7) is then sequentially connected to a soft-water heat exchanger (9) and an air heat exchanger (10) by means of pipes; the air heat exchanger (10) is connected to a VOCS treatment system (11) by means of a pipe, the VOCS treatment system (11) is connected to a second centrifugal fan (12) by means of a pipe, and the second centrifugal fan (12) is further connected to a desolventizer-toaster-dryer-cooler (DTDC) (13); in the desolventizer-toaster-dryer-cooler (DTDC) (13), the upper layer is a DT direct steam layer, and the lower layer is a DT energy-saving layer or a DC hot-air layer; and the desolventizer-toaster-dryer-cooler (DTDC) (13) is connected to the DC cyclone (1) by means of a pipe, thus forming a circulating heat-energy recovery system. By taking advantage of the characteristics of high temperature and high humidity of hot air, the DTDC hot-air waste heat recovery system fully recovers waste heat, reduces the steam consumption of equipment, and decreases the cooling load of a VOCS treatment unit.

Description

A DTDC hot air waste heat recovery system Technical Field

[0001] The utility model relates to the field of waste heat recovery, and in particular to a DTDC hot air waste heat recovery system. Background Art

[0002] In the oilseed processing and extraction workshop, wet meal undergoes desolventizing, toasting (DT), and drying and cooling (DC) in a DTDC (degassing and degassing machine) to produce qualified meal. The DT process generally uses direct steam evaporation to recover the solvent, resulting in high DT meal temperatures and moisture content. The DC process typically uses a combination of hot air dehumidification and cold air cooling. While the air removes heat and moisture, it also removes some odor components (VOCS). The odor components (VOCS) emitted from the DC exhaust often contain excessive levels of non-methane hydrocarbons (NMTHs) and must pass through a VOCS treatment system before being released into the atmosphere.

[0003] In the above process, the dry cooling (DC) hot air will bring out a large amount of odor components (VOCS), and the high temperature and high humidity air, the heat it carries, not only leads to the waste of thermal energy, but also requires a lot of electricity and water for odor control (VOCS treatment).

[0004] To meet national energy conservation and emission reduction requirements, the oil processing and extraction plant needed to design a device to recover waste heat from the DTDC hot air. This recovered waste heat can be used in a variety of ways, typically as follows: heating soft water, which vaporizes under vacuum to produce low-pressure steam, which is then pressurized and superheated to serve as DT direct steam; exchanging heat with the primary steam mixed oil to increase its concentration to over 90%; heating conditioned soft water for soybean heating in the conditioning tower; and heating fresh air entering the DC layer for meal drying. This device performs odor control (VOCS) on the DC exhaust air, reducing the temperature and concentration of odor components (VOCS), thereby reducing the cooling load and operating energy consumption of the odor control (VOCS) system.

[0005] Waste of heat energy, high steam consumption and emission of odor components (VOCS) have always been the most prominent problems in traditional leaching workshops, which are contrary to my country's energy conservation and emission reduction standards.

[0006] Utility Model Content

[0007] Therefore, the technical problem to be solved by the present invention is to provide a DTDC hot air waste heat recovery system.

[0008] The technical solution of the utility model is a DTDC hot air waste heat recovery system, wherein a DC brake is connected to a first centrifugal fan through a pipeline; the first centrifugal fan is connected to the bottom end of the shell side of a falling film evaporator; the top end of the shell side of the falling film evaporator is further connected to the bottom end of the shell side of a mixed oil evaporator through a pipeline; the top end of the shell side of the mixed oil evaporator is further connected to a soft water heat exchanger and an air heat exchanger through pipelines in sequence;

[0009] The air heat exchanger is connected to the VOCS processing system through a pipeline, and the VOCS processing system is connected to the second centrifugal fan through a pipeline. The second centrifugal fan is also connected to a DTDC desiccant. In the DTDC desiccant, the upper layer is a DT direct steam layer, and the lower layer is a DT energy-saving layer or a DC hot air layer. The DTDC desiccant is connected to the DC brake through a pipeline to form a circulating heat recovery system.

[0010] The VOCS treatment system is an odor component treatment system. DTDC stands for Degassing and Drying. DT refers to desolventizing and baking, while DC stands for drying and cooling.

[0011] According to the DTDC hot air waste heat recovery system of the present invention, a soft water receiver is provided at the bottom of the falling film evaporator, the soft water receiver is connected to an automatic soft water replenishment pipe, and the automatic soft water replenishment pipe is connected to a soft water circulation pump. The soft water circulation pump is a centrifugal water pump.

[0012] Furthermore, the soft water circulation pump is connected to the top of the falling film evaporator through a pipeline; a distributor is provided above the top of the falling film evaporator; and a liquid level sensor is provided at the bottom of the falling film evaporator.

[0013] The soft water pipe is connected to the top of the falling film evaporator. A distributor is installed above the top of the falling film evaporator. The soft water passes through the distributor from the top of the falling film evaporator and is evenly distributed into the tube bundle of the falling film evaporator, and flows from top to bottom into the soft water receiver at the bottom of the falling film evaporator.

[0014] According to the DTDC hot air waste heat recovery system of the present invention, the soft water receiver at the bottom of the falling film evaporator is connected to the steam pressure pump through a pipeline; the steam pressure pump is connected to the steam superheater through a pipeline.

[0015] Furthermore, the top of the steam superheater is connected to the DT direct steam layer of the DTDC degassing machine through a pipeline.

[0016] Furthermore, the second centrifugal fan is connected to the DT energy-saving layer or the DC hot air layer of the DTDC degassing machine through a pipeline.

[0017] According to the DTDC hot air waste heat recovery system of the present invention, the mixed oil evaporator is connected to a mixed oil pump via a pipeline. Similarly, a distributor is provided above the top of the mixed oil evaporator to achieve uniform distribution.

[0018] Preferably, the mixed oil pump is connected to the evaporation and desolventizing section via a pipeline. The mixed oil pump is a centrifugal oil pump. A liquid level sensor is configured at the bottom of the mixed oil evaporator.

[0019] According to the DTDC hot air waste heat recovery system of the present invention, the mixed oil evaporator is connected to the vacuum system through a pipeline.

[0020] Furthermore, the mixed oil evaporator is divided into two parts, an upper part and an lower part, and the lower part of the mixed oil evaporator is connected to the vacuum system.

[0021] The structure of the mixed oil evaporator is divided into two parts. The upper part is the tube array, which is longer, and the lower part is shorter. The vacuum system is connected to the lower part of the mixed oil evaporator.

[0022] According to the DTDC hot air waste heat recovery system of the present invention, the soft water heat exchanger is connected to a soft water pipeline; the heated soft water is used for preheating oil or heating other materials.

[0023] According to the DTDC hot air waste heat recovery system of the present invention, the air heat exchanger is connected to a fresh air duct via a pipeline, and the fresh air outlet is connected to the DC layer of the DTDC degassing machine. The heated fresh air enters the DC layer for drying the meal cake.

[0024] According to the DTDC hot air waste heat recovery system of the present invention, a bypass parallel pipe is provided on the connecting pipe between the air heat exchanger and the VOCS processing system.

[0025] Furthermore, a flow control valve is installed on the parallel pipeline.

[0026] The flow control valve is used to adjust the hot air flow in the parallel pipes.

[0027] According to the DTDC hot air waste heat recovery system of the present invention, the DTDC hot air waste heat recovery process is selected from one or more of the following four levels of waste heat recovery: the first level of waste heat recovery is used for desolventizing the oilseed wet meal; the second level of waste heat recovery is used for evaporating the mixed oil solvent; the third level of waste heat recovery is used for heating soft water; the fourth level of waste heat recovery is used for DC drying the meal cake; and finally enters the VOCS treatment system.

[0028] According to the DTDC hot air waste heat recovery system of the utility model, the soft water is heated by DC hot air and flash evaporated to generate low-pressure steam of 400mbarA to 600mbarA, which is then pressurized by a steam pressure pump (5) and superheated by a steam superheater (6) to form low-pressure steam of 1.2-1.6barA.

[0029] The working principle of this utility model is:

[0030] 1) 1st stage waste heat recovery

[0031] After dust removal by the DC brake 1, the DC hot air is pressurized by the first centrifugal fan 2 and enters the bottom of the shell side of the falling film evaporator 3. The soft water circulation pump 4 pumps the soft water a in the soft water receiver at the bottom of the falling film evaporator 3 to the top of the tube side of the falling film evaporator 3. The soft water a is evenly distributed by the distributor and flows downward in a film along the inner wall of the heat exchange tubes of the falling film evaporator 3 to the soft water receiver at the bottom. Some of the soft water a is heated by the DC hot air and flash evaporates to produce low-pressure steam at approximately 400-600 mbarA. Therefore, the soft water receiver requires soft water replenishment, and a liquid level sensor is installed to control the replenishment amount. The low-pressure steam is pressurized by the steam booster pump 5 and superheated by the steam superheater 6 to form low-pressure steam b at approximately 1.2-1.6 barA. This steam is then collected in the DT direct steam drum for use in desolventizing the oilseed wet meal. This reduces the steam consumption of the DT.

[0032] 2) Second stage waste heat recovery

[0033] After the first stage of waste heat recovery, the hot air enters the shell-side of the mixed oil evaporator 7 for heat exchange with the first-stage mixed oil in the tube-side. The mixed oil evaporator 7 is connected to a vacuum system via piping. Under a vacuum of approximately -600 mbar, the n-hexane solvent evaporates, raising the concentration of the first-stage mixed oil to over 90%. The mixed oil is then pumped to the evaporation and desolventizing process via the mixed oil pump 8. This reduces steam consumption for the subsequent second stage of distillation. The n-hexane solvent is subsequently recovered and recycled.

[0034] 3) 3rd stage waste heat recovery

[0035] After the second stage of waste heat recovery, the hot air flows through the soft water heat exchanger 9 to heat the circulating soft water, which is used for preheating oil or other materials, thereby reducing the consumption of tempering heating steam.

[0036] 4) 4th stage waste heat recovery

[0037] After the third stage of waste heat recovery, the hot air flows through the air heat exchanger 10; the hot air and fresh cold air flow in a cross-current (cross-flow), and the heated fresh cold air returns to the DC layer of the DTDC degassing machine 13 to dry the meal cake. This reduces the consumption of hot air heating steam.

[0038] 5) VOCS odor control

[0039] After the fourth stage of waste heat recovery, the hot air enters the VOCS processing system 11 in parallel. A flow control valve regulates the hot air flow in the parallel pipeline, keeping the n-hexane content of the entire DTDC waste heat recovery system below a safe level. The hot air is then pressurized by the second centrifugal fan 12 and returned to the DT energy-saving layer or DC hot air layer of the DTDC degassing unit 13, forming a closed hot air circulation loop.

[0040] The above four-stage waste heat recovery can be designed in different combinations according to specific process requirements.

[0041] The beneficial effects of the utility model are:

[0042] This utility model relates to a waste heat recovery system for DTDC hot air after oil extraction and desolventization. It is suitable for use in oil extraction wet meal degassing (DT) / drying and cooling (DC) units. This system not only reduces steam consumption throughout the oil extraction unit, but also lowers the exhaust temperature of the DC energy-saving layer, reducing the consumption of energy resources such as electricity and water.

[0043] Through the above operation, a DTDC hot air waste heat recovery system provided by the utility model can be realized. The advantages of a DTDC hot air waste heat recovery system provided by the utility model are as follows:

[0044] (1) DTDC hot air is recovered through the first stage of hot air waste heat recovery to generate low-pressure steam of about 1.5 barA. The waste heat recovery efficiency is high, and the recovered heat reuse efficiency is high, and the steam consumption can be saved by about 8 kg / t.

[0045] (2) The DTDC hot air is recovered through the second stage of hot air waste heat and heat exchanged with the steam mixed oil. Under vacuum conditions, the concentration of the steam mixed oil is increased to more than 90%, reducing the steam consumption of the entire device.

[0046] (3) The DTDC hot air is recovered through the third stage of hot air waste heat to heat the soft water in the modulation tower, and the steam consumption can be saved by 6kg / t.

[0047] (4) The DTDC hot air is recovered through the 4th stage of hot air waste heat to heat the fresh air entering the DC layer, and the steam consumption can be saved by 6kg / t.

[0048] (5) After the above-mentioned hot air waste heat recovery, the hot air temperature drops to the normal VOCS inlet temperature range, greatly reducing the cooling load and operating energy consumption of odor control (VOCS treatment).

[0049] In summary, a DTDC hot air waste heat recovery system is not only environmentally friendly but also can bring significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] FIG1 is a schematic diagram of the DTDC hot air waste heat recovery system provided by the present invention.

[0051] In the figure, 1. DC brake, 2. First centrifugal fan, 3. Falling film evaporator, 4. Soft water circulation pump, 5. Steam pressure pump, 6. Steam superheater, 7. Mixed oil evaporator, 8. Mixed oil pump, 9. Soft water heat exchanger, 10. Air heat exchanger, 11. VOCS treatment system, 12. Second centrifugal fan, 13. DTDC evaporator. DETAILED DESCRIPTION

[0052] The specific embodiments of the present invention are described in further detail below with reference to the accompanying drawings.

[0053] In Figure 1, the specific connection method of a DTDC hot air waste heat recovery system is as follows:

[0054] The DC brake 1 is connected to the air inlet of the first centrifugal fan 2 via a pipe. The air outlet of the first centrifugal fan 2 is connected to the hot air inlet of the falling film evaporator 3 via a pipe. The bottom receiver of the falling film evaporator 3 is connected to a soft water circulation pump 4, a steam booster pump 5, and an automatic soft water replenishment line via pipes. The soft water circulation pump 4 is connected to the top of the falling film evaporator 3 via a pipe. The steam booster pump 5 is connected to a steam superheater 6 via a pipe. The steam superheater 6 is equipped with a medium-pressure steam line and a condensate line. The top of the steam superheater 5 is connected to the DTDC degassing unit 13 via a pipe. The top of the shell side of the falling film evaporator 3 is connected to the bottom of the shell side of the mixed oil evaporator 7 via a pipe. The bottom of the mixed oil heat exchanger 7 is connected to a mixed oil pump 8 and a vacuum system via pipes. The top of the tube side of the mixed oil evaporator 7 is connected to a pipeline from a steamed mixed oil; the top of the shell side of the mixed oil evaporator 7 is connected via pipelines to a soft water heat exchanger 9 and an air heat exchanger 10; the air heat exchanger 10 is connected to a VOCS treatment system 11 via pipelines, with another parallel pipeline equipped with a flow control valve serving as a bypass line. The VOCS treatment system 11 is connected via pipelines to another centrifugal fan 12, which is connected via pipelines to the DT energy-saving layer or DC hot air layer of a DTDC degassing machine 13. The DTDC degassing machine 13 is connected via pipelines to the DC degassing machine, forming a closed-loop heat recovery system. The soft water heat exchanger 9 is equipped with a soft water circulation system, which is connected via pipelines to the oil preheater; the air heat exchanger 10 is connected via pipelines to the fresh air intake pipe.

[0055] The technical solution process of this utility model:

[0056] 1) 1st stage waste heat recovery

[0057] After being dusted by a DC cyclone, the DC hot air is pressurized by centrifugal fan 2 and enters the bottom of the shell side of the falling film evaporator 3. A soft water circulation pump 4 pumps soft water a from the soft water receiver at the bottom of the falling film evaporator 3 to the top of the tube side of the evaporator 3. There, it is evenly distributed by a distributor and flows down the inner wall of the heat exchange tubes of the falling film evaporator 3 in a film-like manner to the soft water receiver at the bottom. Some of the soft water a is heated by the DC hot air and flash evaporates to produce low-pressure steam at approximately 400-600 mbarA. Therefore, the soft water receiver requires soft water replenishment, and a level sensor is installed to control the replenishment amount. The low-pressure steam is pressurized by a steam booster pump 5 and superheated by a steam superheater 6 to form low-pressure steam b at approximately 1.5 barA. This steam is then collected in the DT direct steam drum for use in desolventizing the oilseed wet meal.

[0058] 2) Second stage waste heat recovery

[0059] After the first stage of waste heat recovery, the hot air enters the shell side of the mixed oil evaporator 7, where it exchanges heat with the first-stage mixed oil in the tube side. The mixed oil evaporator 7 is connected to a vacuum system via piping. Under a vacuum of approximately -600 mbra, the n-hexane solvent evaporates, raising the concentration of the first-stage mixed oil to over 90%. The mixed oil is then pumped to the evaporation and desolventizing process via the mixed oil pump 8. The n-hexane solvent is subsequently recovered and recycled.

[0060] 3) 3rd stage waste heat recovery

[0061] The hot air after the second stage waste heat recovery flows through the soft water heat exchanger 9 to heat the circulating soft water, which is used for preheating oil or heating other materials.

[0062] 4) 4th stage waste heat recovery

[0063] The hot air after the third stage waste heat recovery flows through the air heat exchanger 10; the hot air and fresh cold air flow in a cross flow (cross flow), and the heated fresh cold air returns to the DC layer of the DTDC (degassing and degassing machine) 13 to dry the meal cake.

[0064] 5) VOCS odor control

[0065] After the fourth stage of waste heat recovery, the hot air enters the VOCS processing system 11 in parallel. A flow control valve controls the flow rate of the hot air in the parallel pipeline, keeping the n-hexane content of the entire DTDC waste heat recovery system below a safe level. The hot air is then pressurized by a centrifugal fan 12 and returned to the DT energy-saving layer or DC hot air layer of the DTDC (degassing and degassing unit) 13, forming a closed hot air circulation loop.

[0066] The above four-stage waste heat recovery can be designed in different combinations according to specific process requirements.

[0067] The specific process flow of this utility model is as follows:

[0068] After being dusted by a DC cyclone, the DC hot air is pressurized by centrifugal fan 2 and enters the bottom of the shell side of the falling film evaporator 3. A soft water circulation pump 4 pumps soft water a from the soft water receiver at the bottom of the falling film evaporator 3 to the top of the tube side of the evaporator 3. There, it is evenly distributed by a distributor and flows down the inner wall of the heat exchange tubes of the falling film evaporator 3 in a film-like manner to the soft water receiver at the bottom. Some of the soft water a is heated by the DC hot air and flash evaporates to produce low-pressure steam at approximately 400-600 mbarA. Therefore, the soft water receiver requires soft water replenishment, and a level sensor is installed to control the replenishment amount. The low-pressure steam is pressurized by a steam booster pump 5 and superheated by a steam superheater 6 to form low-pressure steam b at approximately 1.5 barA. This steam is then collected in the DT direct steam drum for use in desolventizing the oilseed wet meal.

[0069] After the first stage of waste heat recovery, the hot air enters the shell side of the mixed oil evaporator 7, where it exchanges heat with the first-stage mixed oil in the tube side. The mixed oil evaporator 7 is connected to a vacuum system via piping. Under a vacuum of approximately -600 mbra, the n-hexane solvent evaporates, raising the concentration of the first-stage mixed oil to over 90%. The mixed oil is then pumped to the evaporation and desolventizing process via the mixed oil pump 8. The n-hexane solvent is subsequently recovered and recycled.

[0070] The hot air after the second stage waste heat recovery flows through the soft water heat exchanger 9 to heat the circulating soft water, which is used for preheating oil or heating other materials.

[0071] The hot air after the third stage waste heat recovery flows through the air heat exchanger 10; the hot air and fresh cold air flow in a cross flow (cross flow), and the heated fresh cold air returns to the DC layer of the DTDC (degassing and degassing machine) 13 to dry the meal cake.

[0072] After the fourth stage of waste heat recovery, the hot air enters the VOCS processing system 11 in parallel. A flow control valve controls the flow rate of the hot air in the parallel pipeline, keeping the n-hexane content of the entire DTDC waste heat recovery system below a safe level. The hot air is then pressurized by a centrifugal fan 12 and returned to the DT energy-saving layer or DC hot air layer of the DTDC (degassing and degassing unit) 13, forming a closed hot air circulation loop.

[0073] The above four-stage waste heat recovery can be designed in different combinations according to specific process requirements.

[0074] By setting up as above, a DTDC hot air waste heat recovery system can be obtained, which can significantly reduce steam consumption, reduce odor control (VOCS treatment) cooling load and operating energy consumption.

Claims

1. A DTDC hot air waste heat recovery system, characterized by: The DC throttle (1) is connected to the first centrifugal fan (2) through a pipeline; the first centrifugal fan (2) is connected to the bottom end of the shell side of the falling film evaporator (3); the top end of the shell side of the falling film evaporator (3) is connected to the bottom end of the shell side of the mixed oil evaporator (7) through a pipeline; the top end of the shell side of the mixed oil evaporator (7) is connected to the soft water heat exchanger (9) and the air heat exchanger (10) in sequence through pipelines; The air heat exchanger (10) is connected to the VOCS processing system (11) through a pipeline, and the VOCS processing system (11) is connected to the second centrifugal fan (12) through a pipeline, and the second centrifugal fan (12) is also connected to a DTDC degassing machine (13); in the DTDC degassing machine (13), the upper layer is a DT direct steam layer, and the lower layer is a DT energy-saving layer or a DC hot air layer; the DTDC degassing machine (13) is connected to the DC throttle (1) through a pipeline, forming a circulating heat energy recovery system.

2. A DTDC hot air waste heat recovery system according to claim 1, characterized in that: A soft water receiver is provided at the bottom of the falling film evaporator (3), and the soft water receiver is connected to an automatic soft water replenishment pipeline, and the automatic soft water replenishment pipeline is connected to a soft water circulation pump (4).

3. A DTDC hot air waste heat recovery system according to claim 2, characterized in that: The soft water circulation pump (4) is connected to the top of the falling film evaporator (3) through a pipeline; a distributor is provided above the top of the falling film evaporator.

4. The DTDC hot air waste heat recovery system according to claim 1, characterized in that: The soft water receiver at the bottom of the falling film evaporator (3) is connected to a steam booster pump (5) through a pipeline; the steam booster pump (5) is connected to a steam superheater (6) through a pipeline.

5. The DTDC hot air waste heat recovery system according to claim 4, characterized in that: The top of the steam superheater (6) is connected to the DT direct steam layer of the DTDC degassing machine (13) through a pipeline.

6. The DTDC hot air waste heat recovery system according to claim 1, characterized in that: The bottom of the mixed oil evaporator (7) is connected to a mixed oil pump (8) via a pipeline.

7. The DTDC hot air waste heat recovery system according to claim 1, characterized in that: The mixed oil evaporator (7) is connected to the vacuum system via a pipeline.

8. The DTDC hot air waste heat recovery system according to claim 7, characterized in that: The mixed oil evaporator (7) is divided into two parts, an upper part and an lower part, and the lower part of the mixed oil evaporator (7) is connected to the vacuum system.

9. The DTDC hot air waste heat recovery system according to claim 1, characterized in that: The soft water heat exchanger (9) is connected to a soft water pipeline.

10. The DTDC hot air waste heat recovery system according to claim 1, characterized in that: The air heat exchanger (10) is connected to a fresh air duct via a pipeline, and the fresh air outlet is connected to the DC layer in the DTDC degassing machine (13).

11. The DTDC hot air waste heat recovery system according to claim 1, characterized in that: A bypass parallel pipeline is arranged on the connecting pipeline between the air heat exchanger (10) and the VOCS processing system (11).

12. A DTDC hot air waste heat recovery system according to claim 11, characterized in that: A flow control valve is installed on the parallel pipeline.

13. The DTDC hot air waste heat recovery system according to claim 1, characterized in that: The DTDC hot air waste heat recovery process is selected from one or more of the following four levels of waste heat recovery: the first level of waste heat recovery is used for desolventizing the wet oil meal; the second level of waste heat recovery is used for evaporating the mixed oil solvent; the third level of waste heat recovery is used for heating soft water; the fourth level of waste heat recovery is used for DC drying meal cake; and finally enters the VOCS processing system.

14. A DTDC hot air waste heat recovery system according to claim 13, characterized in that: The soft water is heated by DC hot air and flash evaporated to generate low-pressure steam of 400 mbarA to 600 mbarA, which is then pressurized by a steam booster pump (5) and superheated by a steam superheater (6) to form low-pressure steam of 1.2-1.6 barA.

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