An energy-saving production system for dichloromethane distillation column

Abstract

This utility model relates to the field of methane chloride product production technology, specifically providing an energy-saving production system for a dichloromethane distillation column. The vapor from the top of the dichloromethane distillation column is heated and pressurized by a gas compressor, and then used as a heat source for the waste heat reboiler at the bottom of the dichloromethane distillation column. Simultaneously, the bottom material of the dichloromethane distillation column is used as a heat source to preheat the feed to the dichloromethane distillation column, thereby increasing the feed temperature and achieving efficient energy utilization, thus achieving energy conservation and emission reduction.

Description

Technical Field

[0001] This utility model relates to the field of methane chloride product production technology, specifically an energy-saving production system for a dichloromethane distillation tower. Background Technology

[0002] Dichloromethane is a commonly used organic solvent and industrial raw material with strong dissolving and extraction capabilities. It is widely used in the chemical industry for solvent extraction, plastic product manufacturing, coatings, adhesives, and coolants. Furthermore, it is used in the pharmaceutical industry for drug synthesis and in the manufacture of pesticides and insecticides, resulting in significant market demand.

[0003] Currently, the main methods for producing dichloromethane include the chloromethane process, the natural gas chlorination process, and the methanol process. Among these, the chloromethane process is the most widely used. This process uses chloromethane as a raw material and produces dichloromethane through a chlorination reaction. This method has advantages such as readily available raw materials, simple process, and high product purity. During the separation and purification of dichloromethane, the dichloromethane distillation column consumes a large amount of steam. The steam consumption cost of this column accounts for a significant proportion of the product cost. Therefore, effectively reducing the steam consumption of the dichloromethane distillation column is of great importance for enterprises to achieve cost reduction and efficiency improvement.

[0004] Chinese patent CN212789823U discloses a dichloromethane double-effect distillation system. This system uses a dual-tower thermal coupling method to utilize the latent heat of the steam at the top of the tower, thereby reducing the energy consumption of the product. However, this method has problems such as high equipment cost, large footprint, and high operation difficulty. Therefore, how to effectively achieve energy saving and emission reduction in dichloromethane distillation towers has become a common concern for many enterprises. Utility Model Content

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide an energy-saving production system for a dichloromethane distillation column. The vapor from the top of the dichloromethane distillation column is heated and pressurized by a gas compressor and then used as a heat source for the waste heat reboiler at the bottom of the dichloromethane distillation column. At the same time, the bottom material of the dichloromethane distillation column is used as a heat source to preheat the feed to the dichloromethane distillation column, thereby increasing the feed temperature of the dichloromethane distillation column, realizing the effective utilization of energy, and achieving the goal of energy saving and emission reduction.

[0006] To achieve the above-mentioned energy-saving effect, the present invention adopts the following technical solution: An energy-saving production system for a dichloromethane distillation column includes an inlet / outlet heat exchanger 1, a dichloromethane distillation column 2, a waste heat reboiler 4, a gas compressor 5, a material cooler 6, and a reflux tank 9. The top outlet of the dichloromethane distillation column 2 is connected to the inlet of the gas compressor 5, the outlet of the gas compressor 5 is connected to the heat medium inlet of the waste heat reboiler 4, the heat medium outlet of the waste heat reboiler 4 is connected to the material inlet of the material cooler 6, and the material outlet of the material cooler 6 is connected to the inlet of the reflux tank 9; the liquid phase outlet of the reflux tank 9 is connected to the reflux inlet of the dichloromethane distillation column 2 and external equipment respectively through the circulation pump 8. The gas compressor 5 pressurizes and heats the vapor from the top of the column, then uses it as a heat source for the reboiler 4 at the bottom of the dichloromethane distillation column 2. This effectively utilizes the high latent heat carried in the vapor from the top of the column, reduces the amount of external steam used, and achieves energy saving.

[0007] The material outlet of the feed heat exchanger 1 is connected to the material inlet of the dichloromethane distillation column 2; the bottom material outlet of the dichloromethane distillation column 2 is connected to the material inlet of the waste heat reboiler 4 and the heat medium inlet of the feed heat exchanger 1, respectively; and the material outlet of the waste heat reboiler 4 is connected to the bottom material inlet of the dichloromethane distillation column 2.

[0008] Furthermore, the heat medium outlet of the feed heat exchanger 1 is connected to the subsequent crude trichloromethane storage tank.

[0009] The crude trichloromethane produced from the bottom of dichloromethane distillation column 2 also has a certain amount of heat. Using the produced crude trichloromethane as a heat source to heat the feed of dichloromethane distillation column 2 not only cools the crude trichloromethane but also heats the feed, thus making full use of the heat produced by dichloromethane distillation column 2.

[0010] Furthermore, the energy-saving production system of the dichloromethane distillation column also includes a steam reboiler 3. The bottom material outlet of the dichloromethane distillation column 2 is connected to the material inlet of the steam reboiler 3, and the material outlet of the steam reboiler 3 is connected to the bottom material inlet of the dichloromethane distillation column 2.

[0011] The heat medium inlet and outlet of the steam reboiler 3 are both connected to an external heat medium system.

[0012] Furthermore, a discharge pump 7 is installed between the bottom material outlet of the dichloromethane distillation column 2 and the heat medium inlet of the feed heat exchanger 1.

[0013] Furthermore, the reflux tank 9 is provided with a top gas phase outlet for discharging non-condensable gases.

[0014] Furthermore, the refrigerant inlet and outlet of the material cooler 6 are both connected to the public works circulating water system.

[0015] Preferably, the dichloromethane distillation column 2 is a plate column, and the tray type is F1 floating valve tray.

[0016] Preferably, the feed inlet temperature of the feed heat exchanger 1 is 30-35℃, the top temperature of the dichloromethane distillation column 2 is 71-75℃, and the top pressure of the dichloromethane distillation column 2 is 0.18-0.21MPa (gauge pressure); the outlet pressure of the material after compression by the gas compressor 5 is 0.72-0.82MPa (gauge pressure), and the outlet temperature is 110-116℃; the material cooler 6 uses circulating water cooling, and the outlet temperature of the material after cooling is 65-68℃; the mass reflux ratio of the dichloromethane distillation column 2 is 1.5-2.0.

[0017] The beneficial effects of this utility model are: 1. This utility model provides an energy-saving production system for a dichloromethane distillation column. By using a gas compressor to compress the vapor from the top of the column, the vapor is heated and pressurized, and then used as a heat source for the reboiler at the bottom of the dichloromethane distillation column. This effectively utilizes the high latent heat carried in the vapor from the top of the column, reduces the amount of external steam used, and also reduces the amount of circulating water used in the top condenser. Compared with conventional distillation column separation systems, this utility model saves approximately 70%-85% of steam consumption.

[0018] 2. This utility model uses the crude trichloromethane produced at the bottom of the dichloromethane distillation column as a heat source to heat the feed of the dichloromethane distillation column. This not only cools the crude trichloromethane but also heats the feed, thus making full use of the heat generated by the dichloromethane distillation column. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of an energy-saving production system for a dichloromethane distillation column provided in Example 1; The components include: 1. Feed and discharge heat exchangers; 2. Dichloromethane distillation column; 3. Steam reboiler; 4. Waste heat reboiler; 5. Gas compressor; 6. Material cooler; 7. Discharge pump; 8. Circulation pump; and 9. Reflux tank. Detailed Implementation

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0021] Example 1: like Figure 1As shown, an energy-saving production system for a dichloromethane distillation column includes an inlet / outlet heat exchanger 1, a dichloromethane distillation column 2, a steam reboiler 3, a waste heat reboiler 4, a gas compressor 5, a material cooler 6, a discharge pump 7, a circulating pump 8, and a reflux tank 9. The dichloromethane distillation column 2 is a plate column with F1 floating valve trays. The top outlet of the dichloromethane distillation column 2 is connected to the inlet of the gas compressor 5, and the outlet of the gas compressor 5 is connected to the heat medium inlet of the waste heat reboiler 4. The gas compressor 5 compresses the steam from the top of the column, raising its temperature and pressure, and then uses it as the heat source for the waste heat reboiler 4 at the bottom of the dichloromethane distillation column 2. This effectively utilizes the high latent heat carried by the steam from the top of the column and reduces the amount of external steam used.

[0022] The heat medium outlet of the waste heat reboiler 4 is connected to the material inlet of the material cooler 6, and the material outlet of the material cooler 6 is connected to the inlet of the reflux tank 9. The liquid phase outlet of the reflux tank 9 is connected to the inlet of the circulating pump 8, and the outlet of the circulating pump 8 is connected to the reflux inlet of the dichloromethane distillation column 2 and external equipment, respectively. Non-condensable gas is discharged from the top gas phase outlet of the reflux tank 9.

[0023] The material outlet of the feed heat exchanger 1 is connected to the material inlet of the dichloromethane distillation column 2; the bottom material outlet of the dichloromethane distillation column 2 is connected to the inlet of the discharge pump 7, the material inlet of the waste heat reboiler 4, and the material inlet of the steam reboiler 3, respectively, and the outlet of the discharge pump 7 is connected to the heat medium inlet of the feed heat exchanger 1. The heat medium outlet of the feed heat exchanger 1 is connected to the downstream crude trichloromethane storage tank.

[0024] The material outlet of the waste heat reboiler 4 and the material outlet of the steam reboiler 3 are respectively connected to the bottom material inlet of the dichloromethane distillation column 2, and the heat medium inlet and heat medium outlet of the steam reboiler 3 are both connected to an external heat medium system.

[0025] The refrigerant inlet and outlet of the material cooler 6 are connected to the utility circulating water system.

[0026] In this embodiment, the raw material inlet temperature of the feed heat exchanger 1 is 32°C, the top temperature of the dichloromethane distillation column 2 is 71°C, and the top pressure of the dichloromethane distillation column 2 is 0.18 MPa (gauge pressure); the material outlet pressure after compression by the gas compressor 5 is 0.77 MPa (gauge pressure), and the outlet temperature is 113°C; the material cooler 6 uses circulating water cooling, and the temperature at the material outlet of the material cooler 6 after cooling is 67°C; the mass reflux ratio of the dichloromethane distillation column 2 is 1.9, which is similar to that of conventional distillation... Compared to the tower separation system (i.e., without the use of feed heat exchanger 1 and gas compressor 5; the raw material is added to the dichloromethane distillation tower 2 through the material inlet; the steam from the top of the dichloromethane distillation tower 2 enters the material cooler 6 through the top outlet of the dichloromethane distillation tower 2 and the material inlet of the material cooler 6; the heat medium inlet and heat medium outlet of the waste heat reboiler 4 are both connected to an external heat source system; the rest of the process is the same as in this embodiment), the system saves about 73% of steam consumption, achieving energy-saving production.

[0027] Example 2: An energy-saving production system for a dichloromethane distillation column is disclosed in this embodiment, which differs from Embodiment 1 in that the raw material inlet temperature is 35°C, the top temperature of the dichloromethane distillation column 2 is 73°C, and the top pressure of the dichloromethane distillation column 2 is 0.20 MPa (gauge pressure); the outlet pressure of the material after compression by the gas compressor 5 is 0.81 MPa (gauge pressure), and the outlet temperature is 115.6°C; the material cooler 6 uses circulating water cooling, and the outlet temperature of the material after cooling is 68°C; the mass reflux ratio of the dichloromethane distillation column 2 is [not specified]. The efficiency is 1.7, which saves approximately 77% of steam consumption compared to a conventional distillation column separation system (i.e., without the use of feed heat exchangers 1 and gas compressor 5; the raw material is added to the dichloromethane distillation column 2 through the material inlet; the steam from the top of the dichloromethane distillation column 2 enters the material cooler 6 through the top outlet of the dichloromethane distillation column 2 and the material inlet of the material cooler 6; the heat medium inlet and outlet of the waste heat reboiler 4 are both connected to an external heat source system; the rest of the process is the same as in this embodiment).

Claims

1. An energy-saving production system for a dichloromethane distillation column, characterized in that, Includes feed heat exchanger (1), dichloromethane distillation column (2), waste heat reboiler (4), gas compressor (5), material cooler (6), and reflux tank (9); The top outlet of the dichloromethane distillation column (2) is connected to the inlet of the gas compressor (5), the outlet of the gas compressor (5) is connected to the heat medium inlet of the waste heat reboiler (4), the heat medium outlet of the waste heat reboiler (4) is connected to the material inlet of the material cooler (6), and the material outlet of the material cooler (6) is connected to the inlet of the reflux tank (9). The liquid phase outlet of the reflux tank (9) is connected to the reflux inlet of the dichloromethane distillation column (2) and external equipment respectively through the circulation pump (8). The material outlet of the feed heat exchanger (1) is connected to the material inlet of the dichloromethane distillation column (2); the bottom material outlet of the dichloromethane distillation column (2) is connected to the material inlet of the waste heat reboiler (4) and the heat medium inlet of the feed heat exchanger (1), respectively; and the material outlet of the waste heat reboiler (4) is connected to the bottom material inlet of the dichloromethane distillation column (2).

2. The energy-saving production system for dichloromethane distillation column according to claim 1, characterized in that, The heat medium outlet of the feed heat exchanger (1) is connected to the crude chloroform storage tank.

3. The energy-saving production system for dichloromethane distillation column according to claim 1, characterized in that, The energy-saving production system of the dichloromethane distillation tower also includes a steam reboiler (3). The bottom material outlet of the dichloromethane distillation tower (2) is connected to the material inlet of the steam reboiler (3), and the material outlet of the steam reboiler (3) is connected to the bottom material inlet of the dichloromethane distillation tower (2).

4. The energy-saving production system for dichloromethane distillation column according to claim 3, characterized in that, The heat medium inlet and heat medium outlet of the steam reboiler (3) are both connected to an external heat medium system.

5. The energy-saving production system for dichloromethane distillation column according to claim 1, characterized in that, A discharge pump (7) is installed between the bottom material outlet of the dichloromethane distillation column (2) and the heat medium inlet of the feed heat exchanger (1).

6. The energy-saving production system for dichloromethane distillation column according to claim 1, characterized in that, The reflux tank (9) is provided with a top gas phase outlet for discharging non-condensable gases.

7. The energy-saving production system for dichloromethane distillation column according to claim 1, characterized in that, The refrigerant inlet and outlet of the material cooler (6) are both connected to the public works circulating water system.

8. The energy-saving production system for dichloromethane distillation column according to claim 1, characterized in that, The dichloromethane distillation column (2) is a plate column with F1 floating valve trays.

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