Heat recovery photochemical tower

Abstract

The invention discloses a heat recovery photochemical tower. The heat recovery photochemical tower comprises a tower body, a tower kettle, a tower top condenser, a tower kettle reboiler and a compressor. Normal-pressure boiling water exchanges heat with tower top gas through a tower top condenser, and low-pressure steam is formed through flash evaporation. The obtained low-pressure steam is compressed into high-temperature and high-pressure steam through a compressor, and then the high-temperature and high-pressure steam exchanges heat with the tower kettle liquid through a tower kettle reboiler to provide heat for the tower kettle liquid. In the process, the heat of the tower top gas is utilized to supply heat to the tower kettle liquid, and the purpose of energy-saving transformation is achieved by recovering the heat.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical engineering, in particular to a heat recovery photochemical tower. BACKGROUND

[0002] Toluene diisocyanate (TDI) is a common isocyanate compound with high reactivity, which is widely used in polyurethane industry and plays a key role in the production of foam plastics, coatings, adhesives and elastomers.

[0003] The photochemical tower is a typical rectifying tower, which withdraws most of the ODCB solvent from the liquid side line of the rectifying section, thereby removing most of the ODCB in the TDI and ODCB mixed solution. The material containing ODCB, TDI and tar is withdrawn from the tower kettle and enters the subsequent separation step. The photochemical tower is the core device of the TDI separation process, and the problem of high energy consumption caused by high steam consumption or low steam utilization rate is common. Reducing the steam consumption of the photochemical tower and improving the heat utilization rate are the key to energy saving modification of the TDI device. SUMMARY

[0004] The purpose of the present application is to solve the technical defects in the prior art, and to provide a heat recovery photochemical tower. The heat recovery photochemical tower comprises a tower body, a tower kettle, a tower top condenser, a tower kettle reboiler and a compressor. The normal pressure boiling water exchanges heat with the tower top gas through the tower top condenser, and flash evaporation forms low pressure steam. The obtained low pressure steam is compressed into high temperature and high pressure steam by the compressor, and then exchanges heat with the tower kettle liquid through the tower kettle reboiler to provide heat for the tower kettle liquid. This process utilizes the heat of the tower top gas to provide heat for the tower kettle liquid, and achieves the purpose of energy saving modification by recovering heat.

[0005] The technical scheme adopted to achieve the purpose of the present application is:

[0006] A heat recovery photochemical tower, comprising a tower body, a tower kettle, a tower top condenser, a tower kettle reboiler and a compressor;

[0007] A material inlet is formed on the tower body;

[0008] A tower top gas outlet and a condensate return port are formed at the top of the tower body; the tower top gas outlet is in communication with the heat medium inlet of the tower top condenser, and the condensate return port is in communication with the heat medium outlet of the tower top condenser; the tower top gas in the tower body enters the tower top condenser through the tower top gas outlet, is condensed to form condensate, and then returns to the tower body through the condensate return port;

[0009] The tower kettle is provided with a tower kettle liquid outlet and a reboiling tower kettle liquid reflux port; the tower kettle liquid outlet is in communication with the coolant inlet of the tower kettle reboiler, and the reboiling tower kettle liquid reflux port is in communication with the coolant outlet of the tower kettle reboiler; the tower kettle liquid in the tower kettle flows out through the tower kettle liquid outlet, enters the tower kettle reboiler, is heated and reboiled, and then flows back into the tower kettle through the reboiling tower kettle liquid reflux port;

[0010] The inlet of the compressor is in communication with the coolant outlet of the tower top condenser; the outlet of the compressor is in communication with the heat medium inlet of the tower kettle reboiler; the heat medium outlet of the tower kettle reboiler is in communication with the coolant inlet of the tower top condenser; the normal-pressure boiling water in the pipeline exchanges heat with the tower top gas in the tower top condenser as the coolant, and is heated to form low-pressure steam by flashing; the obtained low-pressure steam is compressed by the compressor to obtain high-temperature and high-pressure steam; the obtained high-temperature and high-pressure steam exchanges heat with the tower kettle liquid in the tower kettle reboiler as the heat medium, and the obtained normal-pressure boiling water is returned to the tower top condenser after being cooled.

[0011] In the above technical solution, the tower body is a tray-type rectification tower body.

[0012] In the above technical solution, a side sampling outlet is arranged in the middle of the tower body, so that most of the ODCB solvent is sampled from the liquid phase side line in the rectification section.

[0013] In the above technical solution, an auxiliary reboiler is further arranged; the inlet of the auxiliary reboiler is in communication with the tower kettle liquid outlet; and the outlet of the auxiliary reboiler is in communication with the reboiling tower kettle liquid reflux port.

[0014] In the above technical solution, a tower kettle liquid sampling outlet is arranged at the bottom end of the tower kettle, so that the material containing a small amount of ODCB, TDI and tar is sampled and enters a subsequent separation step.

[0015] In the above technical solution, an auxiliary heater is further arranged on the normal-pressure boiling water pipeline between the heat medium outlet of the tower kettle reboiler and the coolant inlet of the tower top condenser.

[0016] Compared with the prior art, the present application has the following beneficial effects:

[0017] The heat recovery photochemical tower provided by the present application comprises a tower body, a tower kettle, a tower top condenser, a tower kettle reboiler and a compressor. The normal-pressure boiling water exchanges heat with the tower top gas in the tower top condenser to form low-pressure steam by flashing. The obtained low-pressure steam is compressed by the compressor to obtain high-temperature and high-pressure steam, which exchanges heat with the tower kettle liquid in the tower kettle reboiler to provide heat for the tower kettle liquid. The process utilizes the heat of the tower top gas to provide heat for the tower kettle liquid, and the purpose of energy saving and reconstruction is achieved by recovering heat. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The figure is a structural schematic diagram of the heat recovery photochemical tower.

[0019] In the figure: 1-tower body, 1-1-material inlet, 1-2-tower top gas outlet, 1-3- condensate reflux port, 1-4-side outlet, 2-tower kettle, 2-1-tower kettle liquid outlet, 2-2-tower kettle liquid reflux port, 2-3-tower kettle liquid outlet, 3-tower top condenser, 3-1-heat medium inlet, 3-2-heat medium outlet, 3-3-coolant outlet, 3-4-coolant inlet, 4-tower kettle reboiler, 5-compressor, 5-1- inlet, 5-2-outlet, 6-assisted reboiler, 7-assisted heater. DETAILED DESCRIPTION

[0020] The application will be further described below in connection with specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the application and should not be used to limit the application.

[0021] Example 1

[0022] A heat recovery photochemical tower, as shown in the figure, comprises a tower body 1, a tower kettle 2, a tower top condenser 3, a tower kettle reboiler 4 and a compressor 5;

[0023] The tower body 1 is provided with a material inlet 1-1;

[0024] The tower body 1 is provided with a tower top gas outlet 1-2 and a condensate reflux port 1-3 at the top; the tower top gas outlet 1-2 is in communication with the heat medium inlet 3-1 of the tower top condenser 3, and the condensate reflux port 1-3 is in communication with the heat medium outlet 3-2 of the tower top condenser 3; the tower top gas in the tower body 1 enters the tower top condenser 3 through the tower top gas outlet 1-2 to be condensed, and the condensate returns to the tower body 1 through the condensate reflux port 1-3;

[0025] The tower kettle 2 is provided with a tower kettle liquid outlet 2-1 and a reboiling tower kettle liquid reflux port 2-2; the tower kettle liquid outlet 2-1 is in communication with the coolant inlet of the tower kettle reboiler 4, and the reboiling tower kettle liquid reflux port 2-2 is in communication with the coolant outlet of the tower kettle reboiler 4; the tower kettle liquid in the tower kettle 2 flows out through the tower kettle liquid outlet 2-1 to enter the tower kettle reboiler 4, and then returns to the tower kettle 2 through the reboiling tower kettle liquid reflux port 2-2 after being heated and reboiled;

[0026] The inlet 5-1 of the compressor 5 is connected with the refrigerant outlet 3-3 of the overhead condenser 3; the outlet 5-2 of the compressor 5 is connected with the heat medium inlet of the tower kettle reboiler 4; the heat medium outlet of the tower kettle reboiler 4 is connected with the refrigerant inlet 3-4 of the overhead condenser 3; the normal pressure boiling water in the pipeline exchanges heat with the overhead gas in the overhead condenser 3 as the refrigerant, and is heated to form low-pressure steam by flashing; the obtained low-pressure steam is compressed by the compressor 5 to obtain high-temperature and high-pressure steam; the obtained high-temperature and high-pressure steam exchanges heat with the tower kettle liquid in the tower kettle reboiler 4 as the heat medium, and the obtained normal pressure boiling water is returned to the overhead condenser 3 after being cooled.

[0027] Embodiment 2

[0028] A heat recovery photochemical tower, comprising a tower body 1, a tower kettle 2, an overhead condenser 3, a tower kettle reboiler 4 and a compressor 5;

[0029] The tower body 1 is a tray-type rectifying tower body; a material inlet 1-1 is arranged on the tower body 1;

[0030] The tower body 1 is provided with an overhead gas outlet 1-2 and a condensed liquid return port 1-3 at the top; the overhead gas outlet 1-2 is connected with the heat medium inlet 3-1 of the overhead condenser 3, and the condensed liquid return port 1-3 is connected with the heat medium outlet 3-2 of the overhead condenser 3; the overhead gas in the tower body 1 enters the overhead condenser 3 through the overhead gas outlet 1-2, is condensed to form condensed liquid, and then returns to the tower body 1 through the condensed liquid return port 1-3;

[0031] A side outlet 1-4 is arranged in the middle of the tower body; most of the ODCB solvent is taken out from the liquid phase side of the rectifying section;

[0032] The tower kettle 2 is provided with a tower kettle liquid outlet 2-1 and a reboiled tower kettle liquid return port 2-2; the tower kettle liquid outlet 2-1 is connected with the refrigerant inlet of the tower kettle reboiler 4, and the reboiled tower kettle liquid return port 2-2 is connected with the refrigerant outlet of the tower kettle reboiler 4; the tower kettle liquid in the tower kettle 2 flows out through the tower kettle liquid outlet 2-1, enters the tower kettle reboiler 4, is heated and reboiled, and then flows back into the tower kettle 2 through the reboiled tower kettle liquid return port 2-2;

[0033] In order to ensure the reboiling effect, an auxiliary reboiler 6 is further arranged; the inlet of the auxiliary reboiler 6 is connected with the tower kettle liquid outlet 2-1; the outlet of the auxiliary reboiler 6 is connected with the reboiled tower kettle liquid return port 2-2;

[0034] The inlet 5-1 of the compressor 5 is communicated with the refrigerant outlet 3-3 of the overhead condenser 3; the outlet 5-2 of the compressor 5 is communicated with the heat medium inlet of the tower kettle reboiler 4; the heat medium outlet of the tower kettle reboiler 4 is communicated with the refrigerant inlet 3-4 of the overhead condenser 3; the atmospheric boiling water in the pipeline exchanges heat with the overhead gas in the overhead condenser 3 as the refrigerant, and is heated to flash steam to form low-pressure steam; the obtained low-pressure steam is compressed by the compressor 5 to obtain high-temperature and high-pressure steam; the obtained high-temperature and high-pressure steam exchanges heat with the tower kettle liquid in the tower kettle reboiler 4 as the heat medium, and the obtained atmospheric boiling water is returned to the overhead condenser 3 after being cooled. An auxiliary heater 7 is further arranged on the atmospheric boiling water pipeline between the heat medium outlet of the tower kettle reboiler 4 and the refrigerant inlet 3-4 of the overhead condenser 3.

[0035] The tower kettle liquid outlet 2-3 is arranged at the bottom end of the tower kettle, and the material containing a small amount of ODCB, TDI and tar is discharged into the subsequent separation step.

[0036] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A heat recovery photochemical tower characterized by, The tower body, the tower kettle, the tower top condenser, the tower kettle reboiler and the compressor are included. The tower body is provided with a material inlet. The tower top gas outlet is connected with the heat medium inlet of the tower top condenser, and the condensed liquid reflux port is connected with the heat medium outlet of the tower top condenser. The tower kettle is provided with a tower kettle liquid outlet and a reboiling tower kettle liquid reflux port. The material inlet of the compressor is connected with the heat medium outlet of the tower top condenser.

2. The heat recovery photochemical tower of claim 1, wherein, The outlet of the compressor is connected with the heat medium inlet of the tower kettle reboiler.

3. The heat recovery photochemical tower of claim 1, wherein, The heat medium outlet of the tower kettle reboiler is connected with the heat medium inlet of the tower top condenser.

4. The heat recovery photochemical tower of claim 1 wherein, The tower body is a tower plate type rectifying tower body.

5. The heat recovery photochemical tower of claim 1 wherein, The middle part of the tower body is provided with a side sampling outlet.

6. The heat recovery photochemical tower of claim 1 wherein, An auxiliary reboiler is further included. The bottom end of the tower kettle is provided with a tower kettle liquid sampling outlet. An auxiliary heater is arranged on the normal pressure boiling water pipeline between the heat medium outlet of the tower kettle reboiler and the heat medium inlet of the tower top condenser.

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