Tower top gas phase heat recycling system of propyl alcohol pre-rectifying tower

Abstract

The technical problem to be solved by the utility model is to provide the system for recycling the tower top gas phase heat of the propyl alcohol pre-rectifying tower, the tower top gas phase heat of the propyl alcohol pre-rectifying tower is effectively utilized to heat raw materials through the preheater, the energy consumption of the raw materials in the propyl alcohol pre-rectifying tower is reduced, and the purposes of energy conservation and consumption reduction are achieved by recycling the gas phase heat. The device comprises a preheater, a propyl alcohol pre-rectifying tower, a tower top air cooler and a tower top condenser, a tube pass outlet of the preheater is communicated with an inlet of the propyl alcohol pre-rectifying tower, and a tower top gas phase outlet of the propyl alcohol pre-rectifying tower is respectively communicated with an inlet of the tower top air cooler and a shell pass inlet of the preheater; an outlet of the tower top air cooler and a shell pass outlet of the preheater are respectively communicated with a shell pass inlet of the tower top condenser; and a shell pass outlet of the preheater is communicated with a U-shaped pipe.

Description

Technical Field

[0001] The utility model relates to the technical field of chemical rectification, and particularly relates to a system for thermally recycling the gas phase at the top of a propanol pre-rectification tower. Background Art

[0002] In the traditional rectification process of propanol, a downstream product of ethylene, the low-temperature crude propanol after the gas-liquid separation of propionaldehyde hydrogenation directly enters the pre-rectification tower and reaches the separation purpose after being heated by the reboiler of the pre-rectification tower. The gas phase of the pre-rectification tower is generally condensed by an air cooler and a top condenser, and the heat is released into the atmosphere and taken away by circulating water. The above propanol pre-rectification device has obvious heat waste. The low-temperature propanol directly enters the pre-rectification tower, increasing the steam consumption of the reboiler of the pre-rectification tower. During the cooling process of the gas phase at the top of the tower, it will cause the consumption of electric energy and circulating water.

[0003] In order to save energy consumption, the prior art discloses a rectification waste heat recovery and utilization system. The heat transfer medium uses steam condensate. The steam condensate enters the top condenser through the common side water inlet, absorbs the waste heat, and the generated steam is exported through the common side gas outlet and transmitted to the heat-using equipment, so as to realize the recovery and utilization of the waste heat of the rectification tower. Another technology is to disclose a device for recovering and utilizing the heat of the gas phase at the top of a rectification tower. Water is used as a medium to recover the heat at the top of the high-temperature rectification tower, and this heat is used to supply heat to the reboiler at the bottom of the low-temperature rectification tower. At the same time, the heat of the gas phase at the top of the rectification tower can be used across devices. In both of the above two schemes, water is used as the heat transfer medium, and then the heat is transmitted to other heat-using equipment. If the distance from other heat-using equipment is relatively long, heat consumption will also be generated during the transmission, and the waste heat utilization rate is relatively low. Summary of the Utility Model

[0004] The technical problem to be solved by the utility model is to provide a system for thermally recycling the gas phase at the top of a propanol pre-rectification tower, which effectively utilizes the gas phase heat at the top of the propanol pre-rectification tower to heat the raw materials through a preheater, reduces the energy consumption of the raw materials in the propanol pre-rectification tower, and realizes the thermal recycling of the gas phase to achieve the purpose of energy conservation and consumption reduction.

[0005] A system for thermally recycling the gas phase at the top of a propanol pre-rectification tower includes a preheater, a propanol pre-rectification tower, a top air cooler and a top condenser;

[0006] The tube side outlet of the preheater is communicated with the inlet of the propanol pre-rectification tower, and the gas phase outlet at the top of the propanol pre-rectification tower is respectively communicated with the inlet of the top air cooler and the shell side inlet of the preheater;

[0007] The outlet of the top air cooler and the shell side outlet of the preheater are respectively communicated with the shell side inlet of the top condenser;

[0008] A U-shaped tube is communicated with the shell side outlet of the preheater.

[0009] Furthermore, the inlet of the tube side of the preheater is connected to the inlet of the propanol pre-distillation column through a bypass pipeline, and a first regulating valve is installed on the bypass pipeline.

[0010] Furthermore, a reboiler is connected in a circulating manner to the bottom of the propanol pre-distillation column.

[0011] Furthermore, the outlet of the shell side of the preheater is sequentially connected to the shell side inlet of the U-shaped tube and the top condenser through a reflux pipeline, and the U-shaped tube is at the lowest position on the reflux pipeline.

[0012] Furthermore, a second regulating valve is provided on the reflux pipeline.

[0013] The beneficial effects achieved by the present utility model compared with the prior art are as follows:

[0014] 1. One way of the high-temperature gas phase from the top of the propanol pre-distillation column is led out from the gas phase outlet and introduced into the shell side of the preheater. The high-temperature gas phase exchanges heat with the low-temperature crude propanol raw material entering the tube side of the preheater. After heat exchange, the raw material changes from gas phase to liquid phase and then enters the top condenser;

[0015] It can effectively utilize the excess heat in the gas phase at the top of the propanol pre-distillation column, reduce the steam consumption of the reboiler of the propanol pre-distillation column at the same time, and also reduce the power consumption of the air cooler at the top of the column, thus reducing the overall energy consumption;

[0016] 2. The outlet of the shell side of the preheater is connected to the U-shaped tube, and the U-shaped tube is at the lowest position on the reflux pipeline. The material after heat exchange in the shell side of the preheater becomes a gas-liquid mixture. During the flow process, due to the action of gravity and inertia force, the gas-liquid mixture separates at the bottom elbow of the U-shaped tube. The liquid accumulates at the bottom of the U-shaped tube due to gravity, and under the action of the gas phase pressure, the condensed liquid after heat exchange flows into the reflux pipeline, blocking the gas from leaking out, improving the heat exchange efficiency and maintaining the pressure balance of the system;

[0017] 3. The inlet of the tube side of the preheater is connected to the inlet of the propanol pre-distillation column through a bypass pipeline, and it can be determined whether the raw material is preheated before entering the propanol pre-distillation column, making the use more flexible. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the system for heat reuse of the gas phase at the top of the propanol pre-distillation column according to the present utility model;

[0019] In the figure: 1. Preheater, 2. Propanol pre-distillation column, 3. Air cooler at the top of the column, 4. U-shaped tube, 5. Top condenser, 6. Reflux pipeline, 7. Second regulating valve, 8. Bypass pipeline, 9. First regulating valve. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present application without creative efforts shall fall within the protection scope of the present application.

[0021] As Figure 1 shown, this embodiment discloses a system for thermally recycling the top gas phase of a propanol pre-distillation column, which includes a preheater 1, a propanol pre-distillation column 2, a top air cooler 3, a U-shaped tube 4, and a top condenser 5. The tube-side outlet of the preheater 1 is connected to the inlet of the propanol pre-distillation column 2 through a pipeline. The top gas phase outlet of the propanol pre-distillation column 2 is respectively connected to the inlet of the top air cooler 3 and the shell-side inlet of the preheater 1 through two pipelines. The outlet of the top air cooler 3 is connected to the shell-side inlet of the top condenser 5 through a pipeline. The shell-side outlet of the preheater 1 is successively connected to the U-shaped tube 4 and the shell-side inlet of the top condenser 5 through a reflux pipeline 6. The U-shaped tube 4 is at the lowest position on the reflux pipeline 6. The length of the U-shaped tube 4 is greater than 200 mm, which can block the leakage of gas, improve the heat exchange efficiency, and maintain the pressure balance of the system.

[0022] A second regulating valve 7 is installed on the reflux pipeline 6. The flow rate of the raw material passing through the preheater 1 can be controlled through the second regulating valve 7, thereby changing the heat exchange efficiency. The tube-side inlet of the preheater 1 is connected to the inlet of the propanol pre-distillation column through a bypass pipeline 8. A first regulating valve 9 is installed on the bypass pipeline 8, which can be used more flexibly according to whether the raw material is preheated before entering the propanol pre-distillation column. The bottom of the propanol pre-distillation column is connected in a cycle with a reboiler, and the reboiler provides heat for the bottom material of the propanol pre-distillation column to achieve gas-liquid separation.

[0023] Taking the 40°C crude propanol after the gas-liquid separation of propionaldehyde hydrogenation as an example of the raw material, the specific working process of the system for thermally recycling the top gas phase of the propanol pre-distillation column in this embodiment is as follows:

[0024] The top gas phase outlet of the propanol pre-distillation column 2 is divided into two paths. One path enters the top air cooler 3, and the other path enters the shell side of the preheater 1 to exchange heat with the 40°C crude propanol from the gas-liquid separation of propionaldehyde hydrogenation in the tube side of the preheater 1. The temperature of the crude propanol after heat exchange can reach 85°C. The 85°C crude propanol directly enters the propanol pre-distillation column and is heated by the reboiler to achieve gas-liquid separation. The gas phase discharged from the shell-side outlet of the preheater 1 is cooled to form a gas-liquid mixture, which is separated by the U-shaped tube 4 and then enters the top condenser 5 of the propanol tower again in liquid form through the reflux pipeline 6 for further cooling. This embodiment can effectively utilize the excess heat in the top gas phase of the propanol pre-distillation column, reduce the steam consumption of the reboiler of the propanol pre-distillation column, and also reduce the power consumption of the top air cooler 3, thereby reducing the overall energy consumption.

Claims

1. A propanol pre-distillation tower top gas phase heat recycling system, characterized in that: It includes a preheater, a propanol pre-distillation tower, a tower top air cooler and a tower top condenser; The tube-side outlet of the preheater is connected to the inlet of the propanol pre-distillation tower, and the top gas phase outlet of the propanol pre-distillation tower is respectively connected to the inlet of the top air cooler and the shell-side inlet of the preheater; The outlet of the tower top air cooler and the shell side outlet of the preheater are respectively connected to the shell side inlet of the tower top condenser; The shell side outlet of the preheater is connected with a U-shaped tube.

2. The propanol pre-distillation tower top gas phase heat recycling system according to claim 1, characterized in that: The tube-side inlet of the preheater is connected to the inlet of the propanol pre-distillation tower through a shortcut pipeline, and a first regulating valve is installed on the shortcut pipeline.

3. The propanol pre-distillation tower top gas phase heat recycling system according to claim 1, characterized in that: The bottom circulation of the propanol pre-distillation tower is connected with a reboiler.

4. The propanol pre-distillation tower top gas phase heat recycling system according to any one of claims 1 to 3, characterized in that: The shell side outlet of the preheater is connected to the U-shaped tube and the shell side inlet of the tower top condenser in sequence through a reflux pipeline, and the U-shaped tube is at the lowest position on the reflux pipeline.

5. The propanol pre-distillation tower top gas phase heat recycling system according to claim 4, characterized in that: A second regulating valve is arranged on the reflux pipeline.

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