A methanol rectification fine methanol production heat optimization system

Abstract

The utility model discloses a kind of methanol rectification refined methanol extraction heat optimization systems, the methanol outlet of pre-distillation column is communicated with the methanol import of pressurized rectification column, the methanol aqueous solution outlet of pressurized rectification column bottom is communicated with the methanol aqueous solution import of atmospheric distillation column, the methanol steam export of pressurized rectification column top is communicated with the reboiler import of atmospheric distillation column, the methanol outlet of reboiler is communicated with the import of pressurized reflux tank, the methanol outlet of pressurized reflux tank bottom is communicated with the import of methanol cooler, the import of the outlet of methanol cooler is communicated with the import of circulating water heat exchanger;The methanol steam export of pressurized reflux tank and atmospheric distillation column top is all connected with the import of atmospheric column condenser.The utility model carries out heat exchange to the methanol of extraction again, to meet the requirement that the methanol temperature in refined methanol intermediate tank is not greater than 40 DEG C. Temperature reduction can also effectively avoid methanol volatilization, reduce methanol loss. Reduce the flammable gas content in tank area surrounding environment.

Description

Technical Field

[0001] This utility model relates to the field of methanol distillation technology, and in particular to a system for optimizing the heat output of refined methanol from methanol distillation. Background Technology

[0002] Methanol distillation unit is a key separation and purification device in the methanol production process. Its main purpose is to remove impurities (such as water, ethanol, higher alcohols, etc.) from crude methanol through distillation, thereby obtaining high-purity methanol products.

[0003] Methanol distillation processes can be classified into single-tower, double-tower, triple-tower, quadruple-tower, and more complex multi-tower distillation processes, depending on the number and configuration of the towers.

[0004] Single-tower distillation:

[0005] Crude methanol is separated by a distillation column. The process is simple, but the product purity is low, making it suitable for applications where methanol purity requirements are not high.

[0006] Twin-tower distillation:

[0007] This process typically includes a pre-concentration tower and a main tower. The pre-concentration tower is mainly used to remove light component impurities, while the main tower is used for further purification of methanol. This process is simple and easy to operate, but it has high energy consumption.

[0008] Three-tower distillation:

[0009] Common configurations include a pre-column, a pressurized column, and an atmospheric column. The pre-column removes light components, while the pressurized and atmospheric columns are used for further separation and purification of methanol.

[0010] Four-tower distillation:

[0011] An additional recovery tower is added to the three-tower system to recover methanol from the side stream or bottom liquid of the atmospheric distillation tower. This process can improve the methanol yield, but it requires higher equipment investment and energy consumption.

[0012] Five-tower triple-effect distillation:

[0013] It consists of a preheating tower, an atmospheric tower, a low-pressure tower, a pressurized tower, and a recovery tower. Through thermal integration technology, the gas phase at the top of the low-pressure tower provides heat to the atmospheric tower, and the gas phase at the top of the pressurized tower provides heat to the low-pressure tower, thereby significantly reducing energy consumption.

[0014] The process can also add an absorption tower to the five-tower system to recover methanol from the exhaust gas, further improving the yield and reducing pollutant emissions.

[0015] Methanol distillation is based on the principles of vapor-liquid equilibrium and mass and heat transfer within the distillation column. By controlling the heating temperature and pressure inside the column, methanol and impurities undergo multiple vaporization and condensation processes on the trays, achieving separation and purification.

[0016] Pressure swing distillation:

[0017] By utilizing the differences in azeotropic composition under different pressures, efficient separation can be achieved through a combination of pressurized and depressurized distillation columns. For example, the pressure swing distillation process for methanol and vinyl acetate can effectively separate azeotropics by appropriately setting the pressure difference.

[0018] Thermal integration technology:

[0019] By coupling and utilizing the heat from multiple towers, the consumption of external steam can be reduced. For example, the five-tower triple-effect distillation process uses thermal integration to utilize excess heat from the top of the pressurized tower for preheating, significantly reducing energy consumption.

[0020] The original design of the methanol distillation unit involved collecting refined alcohol from the reflux tanks of the pressurized distillation column and the atmospheric distillation column, and then transferring it to the methanol metering tank. After heat exchange in the pressurized distillation column reflux tank, the temperature was 40-45℃, while the outlet temperature of the atmospheric distillation column reflux tank was 55℃. The two were then mixed and entered the methanol tank area at a temperature between 46-50℃, which did not meet the design requirement of ≤40℃ for the methanol tank area and posed a safety hazard. Utility Model Content

[0021] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a methanol distillation system for optimizing the heat output of refined methanol.

[0022] This utility model is achieved through the following technical solution:

[0023] A methanol distillation system for optimizing methanol recovery heat includes a pre-distillation column, a pressurized distillation column, a circulating water heat exchanger, a pressurized column reflux tank, an atmospheric distillation column, a methanol cooler, an atmospheric distillation column condenser, an atmospheric distillation column reflux tank, and an atmospheric distillation column reflux pump. The methanol outlet of the pre-distillation column is connected to the methanol inlet of the pressurized distillation column. The methanol-water solution outlet at the bottom of the pressurized distillation column is connected to the methanol-water solution inlet of the atmospheric distillation column. The methanol vapor outlet at the top of the pressurized distillation column is connected to the reboiler inlet of the atmospheric distillation column. The methanol outlet of the device is connected to the inlet of the pressurized tower reflux tank. The methanol outlet at the bottom of the pressurized tower reflux tank is connected to the inlet of the methanol cooler. The outlet of the methanol cooler is connected to the inlet of the circulating water heat exchanger. The methanol vapor outlets at the top of the pressurized tower reflux tank and the atmospheric distillation tower are both connected to the inlet of the atmospheric tower condenser. The outlet of the atmospheric tower condenser is connected to the inlet of the atmospheric tower reflux tank. The outlet of the atmospheric tower reflux tank is connected to the inlet of the atmospheric tower reflux pump. The outlet of the atmospheric tower reflux pump is connected to the inlet of the circulating water heat exchanger.

[0024] The wastewater outlet at the bottom of the atmospheric distillation column is connected to a recovery tower.

[0025] The outlet of the circulating water heat exchanger is connected to a refined methanol intermediate tank.

[0026] There are two reboilers, which are connected to both sides of the atmospheric distillation column.

[0027] The methanol outlet at the bottom of the pressurized tower reflux tank is also connected to a pressurized tower reflux pump, and the outlet of the pressurized tower reflux pump is connected to the inlet of the pressurized distillation tower.

[0028] The outlet of the atmospheric distillation column reflux pump is also connected to the inlet of the atmospheric distillation column.

[0029] High-efficiency heat utilization:

[0030] The methanol vapor at the top of the pressurized distillation column of this invention provides heat to the reboiler of the atmospheric distillation column, realizing efficient heat recovery and utilization and significantly reducing steam consumption.

[0031] The methanol is further cooled by a circulating water heat exchanger, which further recovers heat and improves the thermal efficiency of the entire system.

[0032] High product quality:

[0033] This invention utilizes a multi-stage separation process involving a pre-distillation column, a pressurized distillation column, and an atmospheric distillation column to effectively remove impurities from crude methanol and produce a high-purity refined methanol product.

[0034] Energy conservation and consumption reduction:

[0035] This utility model system is reasonably designed. Through heat recovery and recycling, it reduces the consumption of external steam and lowers production costs.

[0036] The use of a circulating water heat exchanger further reduces the amount of cooling water used and improves the efficiency of water resource utilization.

[0037] Environmental friendliness:

[0038] The wastewater at the bottom of the atmospheric distillation column of this invention enters the recovery tower for treatment, recovering methanol from it, thereby reducing wastewater discharge and lowering environmental pollution.

[0039] High system stability:

[0040] The towers in this invention are connected by pipes and pumps to form a complete circulation system, ensuring the continuity and stability of production.

[0041] The pressurized column reflux tank and the atmospheric column reflux tank are each equipped with a reflux pump, which can flexibly adjust the reflux ratio to ensure the stable operation of the distillation process.

[0042] The advantages of this utility model are:

[0043] This invention achieves efficient heat recovery and utilization through a rational process flow design and equipment configuration, significantly reducing steam consumption and production costs. Simultaneously, the system can produce high-purity refined methanol, exhibiting excellent environmental performance and system stability. This system is particularly suitable for large-scale methanol production, effectively improving production efficiency, reducing energy consumption, and minimizing environmental pollution.

[0044] This invention adds a stainless steel circulating water heat exchanger to the mixing pipelines of the pressurized column reflux tank and the atmospheric column reflux tank in a methanol distillation unit to reheat the extracted methanol (tube side is circulating water, shell side is methanol). This achieves the requirement that the methanol temperature entering the tank area be ≤40℃. After the modification, the methanol temperature entering the tank area is ≤40℃, which meets the design requirements. Furthermore, the lower temperature effectively prevents methanol volatilization and reduces methanol loss. It also reduces the flammable gas content in the surrounding environment of the tank area. Attached Figure Description

[0045] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0046] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the utility model without creative effort are within the scope of protection of the present utility model.

[0047] Example 1: A methanol distillation system for optimizing the heat output of refined methanol includes a pre-distillation column 2, a pressurized distillation column 3, a circulating water heat exchanger 8, a pressurized column reflux tank 5, an atmospheric distillation column 4, a methanol cooler 7, an atmospheric distillation column condenser 10, an atmospheric distillation column reflux tank 11, and an atmospheric distillation column reflux pump 12. The methanol outlet of the pre-distillation column 2 is connected to the methanol inlet of the pressurized distillation column 3. The methanol-water solution outlet at the bottom of the pressurized distillation column 3 is connected to the methanol-water solution inlet of the atmospheric distillation column 4. The methanol vapor outlet at the top of the pressurized distillation column 3 is connected to the reboiler inlet of the atmospheric distillation column 4. The methanol outlet of the boiler 9 is connected to the inlet of the pressurized tower reflux tank 5. The methanol outlet at the bottom of the pressurized tower reflux tank 5 is connected to the inlet of the methanol cooler 7. The outlet of the methanol cooler 7 is connected to the inlet of the circulating water heat exchanger 8. The methanol vapor outlets at the top of the pressurized tower reflux tank 5 and the atmospheric distillation column 4 are both connected to the inlet of the atmospheric tower condenser 10. The outlet of the atmospheric tower condenser 10 is connected to the inlet of the atmospheric tower reflux tank 11. The outlet of the atmospheric tower reflux tank 11 is connected to the inlet of the atmospheric tower reflux pump 12. The outlet of the atmospheric tower reflux pump 12 is connected to the inlet of the circulating water heat exchanger 8.

[0048] The wastewater outlet at the bottom of the atmospheric distillation column 4 is connected to a recovery column 13. The outlet of the circulating water heat exchanger 8 is connected to a refined methanol intermediate tank 14.

[0049] There are two reboilers 9, which are connected to both sides of the atmospheric distillation column 4 respectively.

[0050] Example 2: A methanol distillation system for optimizing the heat output of refined methanol includes a pre-distillation column 2, a pressurized distillation column 3, a circulating water heat exchanger 8, a pressurized column reflux tank 5, an atmospheric distillation column 4, a methanol cooler 7, an atmospheric distillation column condenser 10, an atmospheric distillation column reflux tank 11, and an atmospheric distillation column reflux pump 12. The methanol outlet of the pre-distillation column 2 is connected to the methanol inlet of the pressurized distillation column 3. The methanol-water solution outlet at the bottom of the pressurized distillation column 3 is connected to the methanol-water solution inlet of the atmospheric distillation column 4. The methanol vapor outlet at the top of the pressurized distillation column 3 is connected to the reboiler inlet of the atmospheric distillation column 4. The methanol outlet of the boiler 9 is connected to the inlet of the pressurized column reflux tank 5. The methanol outlet at the bottom of the pressurized column reflux tank 5 is connected to the inlet of the methanol cooler 7. The outlet of the methanol cooler 7 is connected to the inlet of the circulating water heat exchanger 8. The methanol vapor outlets at the top of the pressurized column reflux tank 5 and the atmospheric distillation column 4 are both connected to the inlet of the atmospheric distillation column condenser 10. The outlet of the atmospheric distillation column condenser 10 is connected to the inlet of the atmospheric distillation column reflux tank 11. The outlet of the atmospheric distillation column reflux tank 11 is connected to the inlet of the atmospheric distillation column reflux pump 12. The outlet of the atmospheric distillation column reflux pump 12 is connected to the inlet of the circulating water heat exchanger 8. The methanol outlet at the bottom of the pressurized column reflux tank 5 is also connected to the pressurized column reflux pump 6. The outlet of the pressurized column reflux pump 6 is connected to the inlet of the pressurized distillation column 3. The outlet of the atmospheric distillation column reflux pump 12 is also connected to the inlet of the atmospheric distillation column 4.

[0051] In the methanol distillation process, crude methanol 1 enters pre-distillation column 2 for pre-distillation. After removing residual dissolved gases and other low-boiling-point substances, the crude methanol entering pre-distillation column 2, and the pre-distilled methanol from the bottom of column 2, enters pressurized distillation column 3. In pressurized distillation column 3, the methanol vapor distilled from the top of the column serves as a heat source for the bottom of atmospheric distillation column 4. It is condensed by heat exchange between the reboiler 9 and the bottom liquid of atmospheric distillation column 4. The condensed methanol then enters the pressurized column reflux tank 5. In the pressurized column reflux tank 5, a portion of the methanol is pressurized by the pressurized column reflux pump 6 and returned to the top of pressurized distillation column 3 as reflux liquid. The remaining portion is cooled by refined methanol cooler 7 and further enters the newly added stainless steel circulating water heat exchanger 8 for further heat exchange, becoming refined methanol product, which is then sent to refined methanol intermediate tank 14. Methanol vapor discharged from the pressurized column reflux tank 5 is depressurized and then fed into the methanol vapor pipeline at the top of the atmospheric distillation column. The methanol-water solution flowing from the bottom of the pressurized distillation column 3 enters the atmospheric distillation column 4 under the pressure of the column. Methanol vapor distilled from the top of the atmospheric distillation column 4 mixes with the methanol vapor discharged from the pressurized reflux tank and enters the atmospheric distillation column condenser 10 for condensation. The methanol then enters the atmospheric distillation column reflux tank 11. The methanol in the tank is pressurized by the atmospheric distillation column reflux pump 12, and a portion returns to the top of the column as reflux liquid. The remaining portion mixes with the methanol cooled by the refined methanol cooler 7 and enters the newly added stainless steel circulating water heat exchanger 8 for further heat exchange, becoming refined methanol product sent to the refined methanol intermediate tank 14. The wastewater discharged from the bottom of the atmospheric distillation column 4, containing paraffin and trace amounts of methanol, is sent to the recovery tower 13 for further treatment.

[0052] This invention adds a stainless steel circulating water heat exchanger 8 to reheat the extracted methanol, thereby meeting the requirement that the methanol temperature entering the refined methanol intermediate tank 14 be ≤40℃. The lower temperature also effectively prevents methanol volatilization and reduces methanol loss. It also reduces the content of combustible gases in the surrounding environment of the tank area.

Claims

1. A system for optimizing the heat output of refined methanol from methanol distillation, characterized in that: The system includes a pre-distillation column, a pressurized distillation column, a circulating water heat exchanger, a pressurized column reflux tank, an atmospheric distillation column, a methanol cooler, an atmospheric distillation column condenser, an atmospheric distillation column reflux tank, and an atmospheric distillation column reflux pump. The methanol outlet of the pre-distillation column is connected to the methanol inlet of the pressurized distillation column. The methanol-water solution outlet at the bottom of the pressurized distillation column is connected to the methanol-water solution inlet of the atmospheric distillation column. The methanol vapor outlet at the top of the pressurized distillation column is connected to the reboiler inlet of the atmospheric distillation column. The methanol outlet of the reboiler is connected to... The inlet of the pressurized tower reflux tank is connected, and the methanol outlet at the bottom of the pressurized tower reflux tank is connected to the inlet of the methanol cooler. The outlet of the methanol cooler is connected to the inlet of the circulating water heat exchanger. The pressurized tower reflux tank and the methanol vapor outlet at the top of the atmospheric distillation column are both connected to the inlet of the atmospheric distillation column condenser. The outlet of the atmospheric distillation column condenser is connected to the inlet of the atmospheric distillation column reflux tank. The outlet of the atmospheric distillation column reflux tank is connected to the inlet of the atmospheric distillation column reflux pump. The outlet of the atmospheric distillation column reflux pump is connected to the inlet of the circulating water heat exchanger.

2. The methanol distillation and refined methanol heat recovery optimization system according to claim 1, characterized in that: The wastewater outlet at the bottom of the atmospheric distillation column is connected to a recovery tower.

3. The methanol distillation and refined methanol heat recovery optimization system according to claim 1, characterized in that: The outlet of the circulating water heat exchanger is connected to a refined methanol intermediate tank.

4. The methanol distillation and refined methanol heat recovery optimization system according to claim 1, characterized in that: There are two reboilers, which are connected to both sides of the atmospheric distillation column.

5. The methanol distillation and refined methanol heat recovery optimization system according to claim 1, characterized in that: The methanol outlet at the bottom of the pressurized tower reflux tank is also connected to a pressurized tower reflux pump, and the outlet of the pressurized tower reflux pump is connected to the inlet of the pressurized distillation tower.

6. The methanol distillation and refined methanol heat recovery optimization system according to claim 1, characterized in that: The outlet of the atmospheric distillation column reflux pump is also connected to the inlet of the atmospheric distillation column.

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