Tower bottom temperature control system of rectifying tower

Abstract

The utility model provides a rectifying tower bottom temperature control system. The rectifying tower bottom temperature control system comprises a reboiler, a condensate tank, a tower bottom temperature measuring instrument and a condensate tank flow regulating valve, the reboiler is provided with a hot medium inlet, a hot medium outlet, a cold medium inlet and a cold medium outlet, the cold medium inlet of the reboiler is communicated with a liquid outlet at the bottom of the rectifying tower, the hot medium outlet of the reboiler is communicated with a circulating air inlet of the rectifying tower, and the hot medium inlet of the reboiler is connected with a steam feeding pipeline; a cold medium outlet of the reboiler is communicated with a liquid inlet of the condensate tank; the tower bottom temperature measuring instrument is arranged on the rectifying tower and used for measuring the bottom temperature of the rectifying tower; a discharge line is arranged at the bottom of the condensate tank, and the condensate tank flow regulating valve is arranged on the discharge line and is connected with the tower bottom temperature measuring instrument through a DCS (Distributed Control System). By means of the control device, noise in the technological process and the valve plate abrasion rate generated in the technological process can be reduced, the safety of the whole technological process is improved, and the labor intensity of workers is reduced.

Description

Technical Field

[0001] This utility model relates to the field of chemical equipment technology, specifically to a temperature control system for the bottom of a distillation column. Background Technology

[0002] The isobutane unit utilizes the differences in relative volatility among the components of the material during production. Distillation columns separate the raw material components, causing the mixture to exist in a two-phase flow where the components are distributed differently in the liquid and gas phases. This results in multiple partial vaporizations and condensations, separating the components to obtain the desired product, isobutane. This component separation process employs numerous distillation columns. The reboiler in the distillation column bottoms uses 0.7 MPa low-pressure steam as the heating medium, providing the power for mass and heat transfer in the column system.

[0003] like Figure 1 As shown, in existing isobutane reboilers, the steam flow rate into the reboiler is controlled by adjusting the opening of the flow control valve at the reboiler inlet. The problem with this is:

[0004] 1. Since steam is in the gas phase, the flow control valve will generate a lot of noise when throttling the steam during the flow control process.

[0005] 2. The reboiler uses 0.7MPa low-pressure steam for heating, which is affected by fluctuations in the steam main pressure. When the steam pressure changes, the steam heat load entering the reboiler will also change accordingly, and the flow control valve at the reboiler inlet must also operate synchronously. This requires the operator to adjust the steam flow control valve accordingly, increasing the labor intensity of the operators and reducing the labor productivity of the employees.

[0006] 3. During the throttling process, the valve plate of the steam flow control valve is subjected to the scouring of steam for a long time, resulting in severe wear. Since the flow control valve is interlocked, if the flow control valve cannot be closed completely under the interlocked state, it may cause overpressure in the distillation column system and trigger secondary accidents. Summary of the Invention

[0007] This utility model provides a distillation column bottom temperature control system. This application adds a condensate tank and a condensate level control valve at the rear end of the reboiler condensate outlet. The distillation column bottom temperature measuring instrument is improved from being cascaded with the low-pressure steam feed shut-off valve to being cascaded with the condensate tank flow control valve, so as to solve the above-mentioned problems.

[0008] The technical solution adopted in this utility model is:

[0009] A distillation column bottom temperature control system includes a reboiler, a condensate tank, a bottom temperature measuring instrument, and a condensate tank flow regulating valve;

[0010] The reboiler is equipped with a hot medium inlet, a hot medium outlet, a cold medium inlet, and a cold medium outlet. The cold medium inlet of the reboiler is connected to the bottom liquid outlet of the distillation column, the hot medium outlet of the reboiler is connected to the circulating gas inlet of the distillation column, the hot medium inlet of the reboiler is connected to the steam feed pipeline, and the cold medium outlet of the reboiler is connected to the liquid inlet of the condensate tank. The bottom temperature measuring instrument is installed on the distillation column to measure the bottom temperature of the distillation column. The bottom of the condensate tank is equipped with a discharge line, and the condensate tank flow regulating valve is installed on the discharge line and connected to the bottom temperature measuring instrument through a DCS control system.

[0011] The condensate level controller in this application receives instructions from the bottom temperature controller and adjusts the opening of the condensate level control valve to control the volume of condensate in the condensate tank and the volume of condensate in the reboiler, thereby controlling the amount of steam entering the reboiler.

[0012] Preferably, the condensate tank is equipped with a condensate tank level gauge for measuring the liquid level inside the condensate tank.

[0013] Preferably, a condensate tank thermometer is installed on the condensate tank to measure the temperature of the condensate inside the condensate tank, so as to ensure system safety.

[0014] Preferably, the condensate tank is also provided with a condensate tank vapor phase balance line, which is connected to the steam feed line of the reboiler.

[0015] The function of the condensate tank vapor phase equilibrium line is to ensure the balance of gas and liquid inside the tank, which helps to maintain the stability and safety of the system.

[0016] Preferably, a pressure gauge, a condensate drain valve, and a vent valve are also installed on the heating pipeline of the reboiler.

[0017] In the event of a DCS power failure, the pressure gauge can be used to control the reboiler steam consumption by observing the on-site primary gauge. The vent valve is activated when the steam main pressure exceeds the safety valve's set pressure to protect the reboiler equipment and prevent damage due to excessively high steam main pressure.

[0018] The beneficial effects of this utility model are:

[0019] This application adds a condensate tank and a condensate level control valve at the downstream end of the reboiler condensate outlet. The cascade control of the distillation column bottom temperature measuring instrument and the low-pressure steam feed shut-off valve is improved to cascade control with the condensate tank flow control valve. The noise generated by liquid interception is much less than that of gas; the wear caused by liquid scouring the valve plate is also less than that caused by steam scouring the valve plate; the fluctuation of liquid in the pipe is less than the fluctuation caused by gas, which can reduce the frequency of valve adjustment by operators to a certain extent and improve labor productivity. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the temperature control system at the bottom of an existing distillation column.

[0021] Figure 2 This is a schematic diagram of a distillation column bottom temperature control system according to the present invention.

[0022] Explanation of reference numerals in the attached figures:

[0023] 5-Condensate drain valve; 6-Pressure gauge; 7-Vacuum drain valve; 9-Distillation column; 10-Bottom temperature measuring instrument; 11-Reboiler; 12-Condensate tank level gauge; 14-Condensate tank thermometer; 15-Condensate tank vapor phase balance line; 16-Condensate tank; 19-Condensate tank flow regulating valve; 20-Discharge line. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this utility model clearer, the technical solution of this utility model will be clearly and completely described below in conjunction with the accompanying drawings and a preferred embodiment.

[0025] See Figure 2 A distillation column bottom temperature control system includes a reboiler 11, a condensate tank 16, a bottom temperature measuring instrument 10, and a condensate tank flow regulating valve 19. The reboiler 11 has a hot medium inlet, a hot medium outlet, a cold medium inlet, and a cold medium outlet. The cold medium inlet of the reboiler 11 is connected to the bottom liquid outlet of the distillation column 9, the hot medium outlet of the reboiler 11 is connected to the circulating gas inlet of the distillation column 9, the hot medium inlet of the reboiler 11 is connected to a steam feed line, and the cold medium outlet of the reboiler 11 is connected to the liquid inlet of the condensate tank 16. The bottom temperature measuring instrument 10 is installed on the distillation column 9 and is used to measure the bottom temperature of the distillation column. The bottom of the condensate tank 16 has a discharge line 20, and the condensate tank flow regulating valve 19 is installed on the discharge line 20 and connected to the bottom temperature measuring instrument 10 through a DCS control system. The condensate tank 16 is used to collect the condensate from the reboiler.

[0026] The DCS control system is an existing distillation control system.

[0027] The bottom temperature measuring instrument 10 transmits temperature signals through the bottom temperature controller, which then sends a command to the condensate tank level controller, which in turn adjusts the opening of the condensate tank flow regulating valve 19.

[0028] A condensate tank level gauge 12 is installed on the condensate tank 16. During the production process, the condensate tank level gauge 12 is used to observe the on-site condensate tank level.

[0029] A condensate tank temperature gauge 14 is installed on the condensate tank 16. During the production process, the condensate tank temperature gauge 14 is the primary instrument for measuring the temperature of the condensate inside the condensate tank, and the temperature of the condensate is controlled by observing this gauge.

[0030] A condensate tank vapor balance line 15 is also provided on the condensate tank 16, which is connected to the steam feed line of the reboiler 11. During the production process, the condensate tank vapor balance line 15 is used to control the liquid level and temperature in the condensate tank. When there is too much steam entering the condensate tank, it can return to the reboiler steam feed line through the balance line and continue to be used by the reboiler.

[0031] Pressure gauge 6, condensate drain valve 5, and vent valve 7 are also installed on the heating pipeline of reboiler 11. During production, if the pressure gauge fails to power the DCS, the steam consumption of the reboiler can be controlled by observing the primary gauge on site. The vent valve is activated when the pressure in the main steam pipe exceeds the safety valve's set pressure to protect the reboiler equipment and prevent damage to the equipment due to excessively high pressure in the main steam pipe.

[0032] The specific operation of this system can be divided into two situations: when the temperature at the bottom of the distillation column increases and when the temperature at the bottom of the distillation column decreases.

[0033] When the temperature at the bottom of the distillation column rises, the bottom temperature measuring instrument 10 transmits the information back to the DCS control system. To reduce the bottom temperature, the bottom temperature controller sends a command to the condensate level controller, which in turn sends a logic signal to the condensate level control valve 19 to close the valve. The output signal of the condensate level control valve 19 decreases, and the opening of the valve closes accordingly. This reduces the discharge rate from the condensate outlet line 20, increases the condensate volume in the reboiler 11, and increases the effective heat exchange space occupied by the condensate in the reboiler 11. Consequently, the effective heat exchange area of ​​the reboiler 11 decreases, steam consumption decreases, and the low-pressure steam feed rate decreases. The heat load on the reboiler 11 decreases, and the bottom temperature returns to a stable level, achieving effective control of the bottom temperature rise.

[0034] When the temperature at the bottom of the distillation column drops, the bottom temperature measuring instrument 10 transmits a signal indicating the temperature drop back to the DCS control system. To increase the bottom temperature, the bottom temperature controller sends a command to the condenser level controller, which in turn sends a logic signal to the condensate tank level control valve 19 to open the valve. The output signal of the condensate tank level control valve 19 increases, and the opening of the valve increases accordingly. This increases the discharge rate in the condensate outlet line 20, reduces the condensate volume in the reboiler 11, decreases the effective heat exchange space occupied by the condensate in the reboiler 11, increases the effective heat exchange area of ​​the reboiler 11, increases steam consumption, increases the low-pressure steam feed rate, raises the heat load of the reboiler 11, and restores the bottom temperature to a stable level, thus achieving effective control of the temperature drop.

Claims

1. A distillation column bottom temperature control system characterized by, Includes a reboiler (11), a condensate tank (16), a bottom temperature measuring instrument (10), and a condensate tank flow regulating valve (19). The reboiler (11) is provided with a hot medium inlet, a hot medium outlet, a cold medium inlet and a cold medium outlet. The cold medium inlet of the reboiler (11) is connected to the bottom liquid outlet of the distillation column (9). The hot medium outlet of the reboiler (11) is connected to the circulating gas inlet of the distillation column (9). The hot medium inlet of the reboiler (11) is connected to the steam feed pipeline. The cold medium outlet of the reboiler (11) is connected to the liquid inlet of the condensate tank (16). The bottom temperature measuring instrument (10) is installed on the distillation column (9) to measure the bottom temperature of the distillation column; The bottom of the condensate tank (16) is provided with a discharge line (20), and the condensate tank flow regulating valve (19) is set on the discharge line (20) and connected to the bottom temperature measuring instrument (10) through the DCS control system.

2. A column bottom temperature control system as claimed in claim 1, wherein, A condensate tank level gauge (12) is installed on the condensate tank (16) to measure the liquid level in the condensate tank (16).

3. A column bottom temperature control system as set forth in claim 1 wherein, A condensate tank thermometer (14) is also installed on the condensate tank (16) to measure the temperature of the condensate inside the condensate tank (16).

4. A column bottom temperature control system as set forth in claim 1 wherein, The condensate tank (16) is also equipped with a condensate tank vapor balance line (15), which is connected to the steam feed line of the reboiler (11).

5. A column bottom temperature control system as set forth in claim 1 wherein, A pressure gauge (6), a condensate drain valve (5), and a vent valve (7) are also installed on the heating pipeline of the reboiler (11).

Images