Methanol aqueous solution heat pump rectification system

Abstract

The utility model discloses a methanol aqueous solution heat pump rectification system which comprises a first-stage preheater, a second-stage preheater, a third-stage preheater, a rectification tower, a compressor, an evaporator, a condensate water tank, a stripping tower, a reboiler, a first pump, a second pump and a third pump. According to the utility model, the methanol in the methanol aqueous solution can be extracted with high purity in a rectification manner, the treated wastewater can be directly discharged after reaching the discharge standard, the heat pump system reduces the consumption of steam and circulating water, and compared with the traditional process, the energy consumption is reduced, and the operation cost is saved.

Description

Technical Field

[0001] The utility model relates to the technical field of distillation systems, in particular to a methanol-water solution heat pump distillation system. Background Art

[0002] The distillation process of methanol is an important link to ensure its product quality, and the energy consumption in this process is also a key factor affecting its production cost; and traditional distillation equipment is large in size and high in energy consumption. In contrast, heat pump distillation system technology has become one of the important technologies for reducing energy consumption and clean production capacity. The methanol distillation system process has significant energy-saving effects, considerable economic benefits, and relatively simple operation. However, the methanol distillation system technology will be affected by many factors in actual production, especially when the temperature difference between the top of the distillation tower and the bottom of the tower is large. The use of the heat pump distillation system process will result in a very high compression ratio, resulting in an increase in the power of the compressor, an unclear energy-saving effect, and insufficient energy utilization.

[0003] Therefore, improving the energy efficiency ratio and output temperature of the heat pump is the development direction of the methanol distillation system technology. Utility Model Content

[0004] The utility model aims to provide a methanol-water solution heat pump distillation system, which can not only reduce energy consumption and save operating costs, but also ensure that heavy component wastewater can be discharged in compliance with standards.

[0005] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a methanol-water solution heat pump distillation system, comprising a primary preheater, a secondary preheater, a tertiary preheater, a distillation tower, a compressor, an evaporator, a condensed water tank, a distillation tower, a reboiler, a first pump, a second pump and a third pump, the primary preheater is provided with a raw material inlet, the primary preheater, the secondary preheater, the tertiary preheater and the distillation tower are connected in sequence, the air outlet at the top of the distillation tower is connected to the air inlet of the evaporator through the compressor, the air outlet at the top of the evaporator is connected to the air inlet at the bottom of the distillation tower, the water outlet at the side of the evaporator is connected to the condensed water tank, the air ... The water outlet at the bottom of the condensate tank is connected to the water inlet at the bottom of the first-stage preheater through a first pump, and the first-stage preheater is provided with a light component extraction port, the water outlet at the bottom of the rectifying tower and the water outlet at the bottom of the evaporator are connected to the water inlet at the top of the distillation tower through a second pump, the interface on the side of the distillation tower is connected to the interface at the top of the reboiler, the air outlet at the top of the distillation tower is connected to the air inlet on the side of the distillation tower, the water outlet at the bottom of the distillation tower and the water outlet at the bottom of the reboiler are connected to the water inlet at the bottom of the second-stage preheater through a third pump, and the second-stage preheater is provided with a heavy component extraction port.

[0006] Among them, the first-stage preheater, the second-stage preheater and the third-stage preheater are the three-stage preheating system of raw materials, and the purpose is to heat the raw materials to the designed feed temperature.

[0007] The main purpose of the evaporator and reboiler is to evaporate the material. The heat source of the evaporator is the material steam after being pressurized and heated by the compressor; the heat source of the reboiler is the raw steam.

[0008] The main purpose of the distillation tower and evaporator is to make the produced methanol reach a set concentration.

[0009] The main purpose of the stripping tower and reboiler is to make the extracted tower bottom waste water reach a set concentration.

[0010] The main purpose of the compressor is to pressurize and heat the material vapor at the top of the distillation tower, so that the material vapor at the compressor outlet provides heat for the system and reduces the steam consumption.

[0011] The utility model is further configured such that the water inlet at the bottom of the primary preheater and the water inlet at the top of the distillation tower are connected to the first pump through the same pipeline.

[0012] The utility model is further configured that the first-stage preheater, the second-stage preheater and the third-stage preheater are tubular heat exchangers or spiral plate heat exchangers or wound tube heat exchangers or plate heat exchangers.

[0013] The utility model is further configured that the compressor is a piston compressor, a screw compressor, a centrifugal compressor or a linear compressor.

[0014] The utility model has the following beneficial effects: methanol in methanol aqueous solution can be extracted with high purity by distillation, and the treated wastewater meets the discharge standard and can be directly discharged; the heat pump system reduces the consumption of steam and circulating water, reduces energy consumption compared with traditional processes, and saves operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Methanol water heat pump distillation process flow chart.

[0016] In the figure: 1. primary preheater; 2. secondary preheater; 3. tertiary preheater; 4. distillation tower; 5. compressor; 6. evaporator; 7. condensate tank; 8. stripping tower; 9. reboiler; 10. first pump; 11. second pump; 12. third pump; 13. raw material inlet; 14. light component extraction outlet; 15. heavy component extraction outlet. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] Embodiment 1

[0019] As attached Figure 1 A methanol-water solution heat pump distillation system is shown, the raw materials are 65% methanol and 35% water; the treatment requirements are that the methanol water content is ≤0.5%, and the water content of methanol is ≤0.5%. The 25°C methanol-water solution is first heat-exchanged with the extracted material in the primary preheater 1, the raw material and the residual in the still of the stripping tower 8 are heat-exchanged in the secondary preheater 2, the raw material and the raw steam are heated to 60°C in the tertiary preheater 3, the heated raw material enters the distillation tower 4, the liquid flows into the evaporator 6, the gas enters the compressor 5 from the top of the tower and then enters the evaporator 6 to provide heat for the evaporator 6, the liquid flows into the condensed water tank 7, the methanol water with less than or equal to 30% in the still of the distillation tower 4 enters the stripping tower 8, the liquid flows into the reboiler 9, and the gas enters the distillation tower 4 from the top of the stripping tower 8 under the heating of the raw steam, and a part of the gas at the top of the distillation tower 4 after heat exchange is refluxed and a part is provided to the preheater to produce methanol with a water content of less than 0.5%, and the still of the stripping tower 8 produces wastewater with a methanol content of less than 0.5%.

[0020]

[0021] Explanation of the attached table

[0022] Table 1

[0023] Embodiment 2

[0024] By calculating the energy consumption of the utility model and the energy consumption of conventional distillation, it is concluded that the utility model consumes 1.5t of steam per hour, 86t of circulating water per hour, the power of the pump is 50KW and the power of the compressor 5 is 320KW, the conventional distillation consumes 4.73t of steam per hour, 280t of circulating water per hour, the power of the pump is 4.5KW, with 300 yuan per ton of steam, 0.5 yuan per ton of circulating water, and 0.8 yuan per kilowatt of electricity, it is calculated that the annual operating cost of the present invention is 5.68 million yuan, the annual operating cost of conventional distillation is 11.25 million yuan, and the utility model can save 5.57 million yuan in operating costs per year. When purifying methanol of the same concentration, the operating cost of conventional distillation is high and it is difficult to meet the purification requirements, and the kettle residue is also difficult to meet the requirements. After adding a stripping tower 8 and using a heat pump system, the operating cost is reduced and it is easier to meet the purification requirements, and the kettle residue is also easier to meet the requirements.

Claims

1. A methanol-water solution heat pump distillation system, characterized in that: The invention comprises a primary preheater (1), a secondary preheater (2), a tertiary preheater (3), a distillation tower (4), a compressor (5), an evaporator (6), a condensed water tank (7), a stripping tower (8), a reboiler (9), a first pump (10), a second pump (11) and a third pump (12); the primary preheater (1) is provided with a raw material inlet (13); the primary preheater (1), the secondary preheater (2), the tertiary preheater (3) and the distillation tower (4) are connected in sequence; the air outlet at the top of the distillation tower (4) is connected to the air inlet of the evaporator (6) through the compressor (5); the air outlet at the top of the evaporator (6) is connected to the air inlet at the bottom of the distillation tower (4); the water outlet at the side of the evaporator (6) is connected to the water inlet at the top of the condensed water tank (7) The water outlet at the bottom of the condensed water tank (7) is connected to the water inlet at the bottom of the primary preheater (1) through a first pump (10), and a light component extraction port (14) is provided on the primary preheater (1), the water outlet at the bottom of the rectifying tower (4) and the water outlet at the bottom of the evaporator (6) are connected to the water inlet at the top of the stripping tower (8) through a second pump (11), the interface at the side of the stripping tower (8) is connected to the interface at the top of the reboiler (9), the air outlet at the top of the stripping tower (8) is connected to the air inlet at the side of the rectifying tower (4), the water outlet at the bottom of the stripping tower (8) and the water outlet at the bottom of the reboiler (9) are connected to the water inlet at the bottom of the secondary preheater (2) through a third pump (12), and a heavy component extraction port (15) is provided on the secondary preheater (2).

2. A methanol-water solution heat pump distillation system according to claim 1, characterized in that: The water inlet at the bottom of the primary preheater (1) and the water inlet at the top of the distillation tower (4) are connected to the first pump (10) through the same pipeline.

3. A methanol-water solution heat pump distillation system according to claim 1, characterized in that: The first-stage preheater (1), the second-stage preheater (2), and the third-stage preheater (3) are tubular heat exchangers, spiral plate heat exchangers, wound tube heat exchangers, or plate heat exchangers.

4. A methanol-water solution heat pump distillation system according to claim 1, characterized in that: The compressor (5) is a piston compressor, a screw compressor, a centrifugal compressor or a linear compressor.

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