Energy-saving device for methanol rectification in hydrogen peroxide purification process
By adding a methanol tower to the hydrogen peroxide purification unit and adopting double-effect distillation, and using the top steam of the methanol tower and surplus hot water from the plant as heat sources, the problem of high energy consumption of the methanol tower was solved, and a significant reduction in energy consumption was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- HUNAN BAILI ENGINEERING SCIENCE AND TECHNOLOGY CO LTD
- Filing Date
- 2025-06-26
- Publication Date
- 2026-07-21
AI Technical Summary
The methanol tower in existing hydrogen peroxide purification devices has high energy consumption, mainly because the heat source comes entirely from reboiler steam, resulting in large consumption of steam and circulating water.
A second methanol tower is added before the existing methanol tower, using double-effect distillation. The first methanol tower uses negative pressure distillation, and the heat source is the top steam of the second methanol tower and/or the surplus hot water from the plant, thereby reducing the consumption of steam and circulating water.
By reducing the amount of steam and circulating water used in the methanol distillation process, energy consumption was significantly reduced, saving approximately 4 t/h of low-pressure steam consumption and approximately 147 t/h of circulating water consumption.
Smart Images
Figure CN224523989U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of chemical technology and relates to an energy-saving device for methanol distillation in the hydrogen peroxide purification process. Background Technology
[0002] In the hydrogen peroxide production process, crude hydrogen peroxide is purified by extraction and then needs to be purified by a resin adsorption tower to further remove organic impurities to meet the quality requirements of downstream caprolactam products. The saturated resin is regenerated with methanol, and the regenerated crude methanol and dilute methanol are pumped to a methanol distillation tower for purification. The purified methanol is then recycled.
[0003] The existing hydrogen peroxide purification unit uses low-pressure steam as a heat source for atmospheric pressure distillation in its methanol tower. The methanol distilled from the top of the tower is recycled, while the residue in the bottom of the tower is sent to a waste liquid concentration unit for treatment. Because the current technology relies entirely on reboiler steam for the methanol tower's heat source, the consumption of methanol tower steam and circulating water is large, resulting in high energy consumption. Utility Model Content
[0004] The purpose of this invention is to provide an energy-saving device and process for methanol distillation in the hydrogen peroxide purification process. A methanol tower is added before the existing methanol tower (hereinafter referred to as methanol tower two), employing double-effect distillation. Methanol tower one uses negative pressure distillation, and the reboiler heat source uses the top steam from methanol tower two and / or surplus hot water from the plant, reducing the amount of steam and circulating water used in the methanol distillation process, thereby lowering energy consumption.
[0005] Technical solution of this utility model An energy-saving device for methanol distillation in a hydrogen peroxide purification process comprises a methanol tower feed preheater, a methanol tower, a methanol tower condenser, a methanol tower reflux tank, a methanol tower bottom pump, a methanol tower reboiler, a methanol tower reflux pump, a methanol tower secondary tower, a methanol tower secondary tower condenser, a methanol tower reflux tank, a methanol tower reboiler, a methanol tower bottom pump, a methanol tower reflux pump, and a refined methanol storage tank. The device is characterized in that: the cold-side inlet of the methanol tower feed preheater is connected to pipelines for crude methanol and dilute methanol, the cold-side outlet is connected to the middle of the methanol tower, the hot-side inlet is connected to the top steam pipeline of the methanol tower secondary tower, and the hot-side outlet is connected to the reboiler of the methanol tower and / or the condenser of the methanol tower secondary tower; the top steam pipeline of the methanol tower is connected to the condenser of the methanol tower, and the outlet of the methanol tower condenser is connected to... The methanol tower reflux tank is connected, and its outlet is connected to the methanol tower reflux pump. The outlet of the methanol tower reflux pump is connected to the upper part of the methanol tower and the refined methanol storage tank. The methanol tower bottom outlet is connected to the inlet of the methanol tower bottom liquid pump. The outlet of the methanol tower bottom liquid pump is connected to the lower part of the methanol tower 2. The methanol tower 1 is equipped with a methanol tower reboiler. The top gas phase outlet of the methanol tower 2 is connected to the methanol tower reboiler and / or the hot side inlet of the methanol tower feed preheater. The methanol tower 2 condenser outlet is connected to the methanol tower reflux tank. The methanol tower reflux tank is connected to the inlet of the methanol tower reflux pump. The outlet of the methanol tower reflux pump is connected to the upper part of the methanol tower 2 and the refined methanol storage tank. The methanol tower bottom outlet is connected to the inlet of the methanol tower bottom liquid pump. The methanol tower 2 is equipped with a methanol tower reboiler.
[0006] The methanol tower is connected to a vacuum facility; specifically, the methanol tower condenser is connected to the vacuum pump inlet, the exhaust gas from the vacuum pump outlet is treated before being discharged, and a bypass and pressure regulating valve are installed between the vacuum pump outlet pipe and the inlet pipe to control the pressure of the methanol tower.
[0007] The methanol reboiler can be multiple units, preferably 2-4 units, and can be heated by surplus hot water from the plant and / or steam from the top of the methanol tower and / or its steam condensate, depending on the actual situation.
[0008] An energy-saving process for methanol distillation in a hydrogen peroxide purification process is disclosed. The crude methanol and dilute methanol produced in the hydrogen peroxide purification process exchange heat with methanol vapor from the top of the second methanol tower before entering the first methanol tower. Double-effect distillation is used to remove water and heavy components from the methanol and recover the methanol. The first methanol tower operates under negative pressure with a top pressure of 20~95 kPa (A) (absolute pressure). The heat source for the reboiler of the first methanol tower is the top steam from the second methanol tower and / or surplus hot water from the plant. The top steam from the second methanol tower first exchanges heat with the feed before entering the reboiler of the first methanol tower, and then is condensed in the condenser of the second methanol tower or directly condensed in the condenser of the second methanol tower.
[0009] The methanol and a small amount of water coming out from the top of the methanol tower are methanol and a small amount of water. After being condensed by the methanol tower condenser, the condensate flows into the methanol tower reflux tank. Part of the reflux liquid is sent back to the top of the methanol tower as reflux by the methanol tower reflux pump, and part is sent to the refined methanol storage tank for recycling.
[0010] The bottom of the first methanol tower contains water and heavy components with a small amount of methanol, which are pumped to the second methanol tower.
[0011] Double-effect distillation is used to remove water and heavy components from crude methanol. In the second methanol tower, methanol and some water are distilled off from the top of the tower and enter the feed preheater of the first methanol tower as its heat source to preheat the feed of the first methanol tower. Then it enters the reboiler of the first methanol tower, and then flows into the reflux tank of the second methanol tower after being condensed or directly condensed in the condenser of the second methanol tower. Part of the reflux liquid is sent back to the top of the second methanol tower as reflux by the reflux pump of the second methanol tower, and part is sent to the refined methanol storage tank for recycling. The bottom liquid of the second methanol tower is a residual liquid containing water, heavy components and a small amount of methanol. It is pumped to the waste liquid incineration for treatment.
[0012] The energy-saving process of methanol distillation of this utility model will be further explained below: Energy-saving processes used in methanol distillation during hydrogen peroxide purification include, for example... Figure 1 As shown, the process is as follows: Crude methanol and dilute methanol are pumped to the methanol tower feed preheater by the methanol tower feed pump, and then enter the middle of the methanol tower, where most of the methanol is recovered. The gas phase exiting from the top of the methanol tower consists mostly of methanol and a small amount of water. After being condensed in the methanol tower condenser, the condensate flows into the methanol tower reflux tank. Part of the reflux liquid is pumped back to the top of the methanol tower as reflux, and part is sent to the refined methanol storage tank for recycling. The bottom liquid of the methanol tower consists of water, a small amount of methanol, and heavy components, and is pumped to the methanol tower 2.
[0013] In the methanol tower 2, methanol and a small amount of water, after the heavy components have been removed, are distilled off from the top of the tower and enter the methanol tower 1 feed preheater for heat exchange with the methanol tower 1 feed. After heat exchange, the mixture enters the methanol tower 1 reboiler and then is condensed in the methanol tower 2 condenser, or directly condensed in the methanol tower 2 condenser. The condensate flows into the methanol tower 2 reflux tank. Part of the reflux liquid is pumped back to the top of the methanol tower 2 as reflux, and part is sent to the refined methanol storage tank for recycling. The bottom liquid of the methanol tower 2 is a residual liquid containing water, heavy components, and a small amount of methanol. It is pumped to the waste liquid incineration unit for treatment.
[0014] Features and effects of this utility model This energy-saving process adds a methanol tower (tower 1) before the single-tower operation process, connecting it in series with a methanol tower (tower 2) using a double-effect distillation method. The methanol tower 1 employs negative pressure distillation, lowering the operating temperature. Simultaneously, it uses the overhead steam from the methanol tower 2 and / or surplus hot water from the plant as the heat source for the reboiler of the methanol tower 1, reducing steam and circulating water consumption. Furthermore, it uses the overhead vapor from the methanol tower 2 as the feed heat source for the methanol tower 1, saving hot water and circulating water consumption. Since most of the methanol is distilled from the top of the methanol tower 1, the steam consumption of the methanol tower 2 reboiler is significantly reduced. Attached Figure Description
[0015] Figure 1 , one Energy-saving process for methanol distillation in hydrogen peroxide purification In the diagram: 1-Methanol Tower 1, 2-Methanol Tower 1 Condenser, 3-Methanol Tower 1 Reflux Tank, 4-Methanol Tower 1 Feed Preheater, 5-Methanol Tower 1 Reboiler, 6-Methanol Tower 1 Hot Water Reboiler, 7-Methanol Tower 1 Bottom Liquid Pump, 8-Methanol Tower 1 Reflux Pump, 9-Methanol Tower 2, 10-Methanol Tower 2 Condenser, 11-Methanol Tower 2 Reflux Tank, 12-Methanol Tower 2 Reboiler, 13-Methanol Tower 2 Bottom Liquid Pump, 14-Methanol Tower 2 Reflux Pump, 15-Refined Methanol Storage Tank, 16-Vacuum Pump.
[0016] WCS - Circulating cooling water, WHS - Hot water, LS - Low-pressure steam. Detailed Implementation
[0017] The present invention will be further described below with reference to the accompanying drawings, but this does not constitute a further limitation on the present invention.
[0018] Energy-saving process flow for methanol distillation in hydrogen peroxide purification, such as... Figure 1 As shown.
[0019] Crude methanol and dilute methanol are fed to the methanol tower feed preheater (4) by the methanol tower feed pump and then enter the middle of the methanol tower (1), where most of the methanol is recovered. The gas phase coming out from the top of the methanol tower (1) is mostly methanol and a small amount of water. After being condensed by the methanol tower condenser (2), the condensate flows into the methanol tower reflux tank (3). Part of the reflux liquid is sent back to the top of the methanol tower (1) as reflux by the methanol tower reflux pump (8), and part is sent to the refined methanol storage tank (15) for recycling. The bottom liquid of the methanol tower (1) is water, a small amount of methanol and heavy components, which is sent to the methanol tower (9) by the methanol tower bottom liquid pump (7).
[0020] The gas phase outlet pipe of the methanol tower condenser (2) is connected to the inlet of the vacuum pump (16). The exhaust gas from the outlet of the vacuum pump (16) is discharged after treatment. A bypass and pressure regulating valve are installed between the outlet pipe and the inlet pipe of the vacuum pump (16) to control the pressure of the methanol tower (1).
[0021] In the methanol tower 2 (9), methanol and a small amount of water, after the heavy components have been removed, are distilled off from the top of the tower and enter the methanol tower 1 feed preheater (4) to exchange heat with the feed of methanol tower 1 (1). After heat exchange, the feed enters the methanol tower 1 reboiler (5) and then is condensed by the methanol tower 2 condenser (10) or directly by the methanol tower 2 condenser (10). The condensate flows into the methanol tower 2 reflux tank (11). Part of the reflux liquid is sent back to the top of the methanol tower 2 (9) as reflux by the methanol tower 2 reflux pump (14), and part is sent to the refined methanol storage tank (15) for recycling. The bottom liquid of the methanol tower 2 (9) is a residual liquid containing water, heavy components and a small amount of methanol. It is sent to the waste liquid incineration for treatment by the methanol tower 2 bottom liquid pump (13).
[0022] The hydrogen peroxide production plant with an annual output of 500,000 tons, the process of this utility model can save about 4 t / h of low-pressure steam consumption and about 147 t / h of circulating water consumption compared with the single tower process.
Claims
1. An energy-saving device for methanol distillation in a hydrogen peroxide purification process, comprising a methanol tower feed preheater, a methanol tower, a methanol tower condenser, a methanol tower reflux tank, a methanol tower bottom pump, a methanol tower reboiler, a methanol tower reflux pump, a methanol tower 2, a methanol tower condenser, a methanol tower reflux tank, a methanol tower reboiler, a methanol tower bottom pump, a methanol tower reflux pump, and a refined methanol storage tank, characterized in that: The cold-side inlet of the methanol tower feed preheater is connected to the pipelines for crude methanol and dilute methanol, and the cold-side outlet is connected to the middle section of the methanol tower. The hot-side inlet is connected to the top steam pipeline of the methanol tower 2, and the hot-side outlet is connected to the reboiler of the methanol tower 1 and / or the condenser of the methanol tower 2. The top steam pipeline of the methanol tower 1 is connected to the condenser of the methanol tower 1, the outlet of the condenser of the methanol tower 1 is connected to the reflux tank of the methanol tower 1, the outlet of the reflux tank of the methanol tower 1 is connected to the reflux pump of the methanol tower 1, the outlet of the reflux pump of the methanol tower 1 is connected to the upper part of the methanol tower and the refined methanol storage tank, respectively, and the outlet of the methanol tower 1 kettle is connected to the methanol... The inlet of the bottom liquid pump of the first methanol tower is connected, and the outlet of the bottom liquid pump of the first methanol tower is connected to the lower part of the second methanol tower. The first methanol tower is equipped with a reboiler. The top gas phase outlet of the second methanol tower is connected to the reboiler of the first methanol tower and / or the hot side inlet of the feed preheater of the first methanol tower. The outlet of the condenser of the second methanol tower is connected to the reflux tank of the second methanol tower. The reflux tank of the second methanol tower is connected to the inlet of the reflux pump of the second methanol tower. The outlet of the reflux pump of the second methanol tower is connected to the upper part of the second methanol tower and the refined methanol storage tank respectively. The bottom outlet of the second methanol tower is connected to the inlet of the bottom liquid pump of the second methanol tower. The second methanol tower is equipped with a reboiler.
2. The energy-saving device for methanol distillation in the hydrogen peroxide purification process according to claim 1, characterized in that... The methanol tower condenser is connected to the inlet of the vacuum pump, and the exhaust gas from the vacuum pump outlet is treated before being discharged.
3. The energy-saving device for methanol distillation in the hydrogen peroxide purification process according to claim 1, characterized in that... The methanol reboiler mentioned above consists of multiple units.
4. The energy-saving device for methanol distillation in the hydrogen peroxide purification process according to claim 2, characterized in that... A bypass and pressure regulating valve are installed between the vacuum pump outlet pipe and the inlet pipe.
5. The energy-saving device for methanol distillation in the hydrogen peroxide purification process according to claim 3, characterized in that... The methanol reboiler mentioned above consists of 2-4 units.