Improved structure for forced circulation of rectifying tower

Abstract

The utility model discloses a modified structure for forced circulation of a rectifying tower, and belongs to the field of acetic anhydride production. The device comprises a rectifying tower and a reboiler, the reboiler is mounted at the stripping section of the rectifying tower; an acetic anhydride steam inlet is formed in the side wall of the top end of the rectifying tower stripping section, and an acetic anhydride liquid outlet is formed in the bottom end; the acetic anhydride liquid outlet is connected with a feeding hole of the reboiler through a liquid pipe; the acetic anhydride steam inlet is connected with the discharge hole of the reboiler; an electromagnetic valve a and a forced circulation structure are further arranged on the liquid pipe; the forced circulation structure comprises a forced circulation pump and a circulation pipe, and the forced circulation pump is installed on the circulation pipe; two ends of the circulating pipe are respectively connected to two sides of the electromagnetic valve a on the liquid pipe; and electromagnetic valves b are arranged on the circulating pipe and on the two sides of the forced circulating pump. The flow control range is wider, and circulation is well promoted.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of acetic anhydride production, specifically for a kind of modification structure for rectifying column forced circulation. BACKGROUND

[0002] The function of reboiler in rectifying column is to vaporize liquid again, so as to promote the rectification process. Reboiler vaporizes liquid by heating, and the generated gas phase and liquid phase mixture is sent back to rectifying column, gas phase components pass through tray upwards, and liquid phase components drop to the bottom, so as to constantly replenish the liquid level evaporated and maintain the liquid level balance in column.

[0003] Reboiler is usually used with rectifying column, and rectifying column separates different components in mixture by different volatility, light components are transferred to gas phase, and heavy components are transferred to liquid phase, so as to achieve the purpose of high-purity product. The function of reboiler in rectifying column is not only to heat liquid, but also to promote mass transfer and heat transfer in column through vaporization process, so as to improve separation efficiency.

[0004] The structure of reboiler is similar to that of condenser, but the functions are opposite. Condenser is used for cooling and condensation, while reboiler is used for heating and vaporization. In rectifying column operation, reboiler is usually arranged in stripping section as auxiliary heater to further enhance rectification effect.

[0005] (1) The problem existing in acetic anhydride rectification process is small evaporation capacity.

[0006] (2) After material cooling, it is easy to thicken and block the horizontal pipe connected between rectifying column and reboiler bottom, which causes reboiler to be unable to circulate normally, and the heating in reboiler is dry burning, which causes column tube to be blocked. INVENTION CONTENTS

[0007] Therefore, the utility model provides a kind of modification structure for rectifying column forced circulation, prevent reboiler and rectifying column between circulation not smooth, cause reboiler dry burning to make reboiler column tube block, control flow range is wider, very good promote circulation.

[0008] The specific technical scheme of the utility model is as follows:

[0009] A kind of modification structure for rectifying column forced circulation, including rectifying column and reboiler;The reboiler is installed in the stripping section of rectifying column;

[0010] The top end side wall of the stripping section of the rectifying column is provided with acetic anhydride vapor inlet, and the bottom end is provided with acetic anhydride liquid outlet;

[0011] The acetic anhydride liquid outlet is connected with the feed inlet of reboiler by liquid pipe;Acetic anhydride vapor inlet is connected with the discharge port of reboiler;

[0012] The liquid pipe is further provided with electromagnetic valve a and forced circulation structure; the forced circulation structure comprises forced circulation pump and circulation pipe, and the forced circulation pump is installed on the circulation pipe; two ends of the circulation pipe are connected to two sides of electromagnetic valve a on the liquid pipe respectively;

[0013] Two sides of the forced circulation pump on the circulation pipe are further provided with electromagnetic valve b respectively.

[0014] Further, the side wall of the rectifying column stripping section is further provided with liquid level meter, thermometer and pressure gauge, which are used for detecting the liquid level, temperature and content of acetic anhydride vapor in the acetic anhydride liquid in the stripping section respectively.

[0015] The liquid level meter, the reboiler and the stripping section are located at the same horizontal height; two ports of the liquid level meter are connected to the stripping section through communication pipes, and the pressure gauge is connected to the stripping section through pressure pipe; the pressure pipe and the communication pipe are respectively provided with electromagnetic valve c and electromagnetic valve d.

[0016] Further, the steam inlet pipe of the reboiler is provided with two electromagnetic valves e; a buffer structure is arranged between the two electromagnetic valves e; the buffer structure comprises adjusting valve, flow meter and buffer pipeline.

[0017] The adjusting valve is three-way combined flow adjusting valve, which is installed on the steam inlet pipe near the steam inlet side; one branch port of the adjusting valve is connected to the steam inlet pipe far from the steam inlet side through the buffer pipeline; and the flow meter is installed on the buffer pipeline.

[0018] The beneficial effects generated by the above technical scheme of the utility model are as follows:

[0019] The forced circulation pump is arranged, so that the circulation between the reboiler and the rectifying column is prevented from being not smooth, dry burning of the reboiler is caused, the reboiler tube is blocked, the flow range is wider, and the circulation is promoted well. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The structure composition diagram of the embodiment of the utility model is shown.

[0021] In the drawing: LI, liquid level meter; TI, thermometer; PI, pressure gauge; FV, three-way adjusting valve; FIC, flow meter; XV, hand valve; CP, forced circulation pump. DETAILED DESCRIPTION

[0022] The utility model will be further described below in combination with the drawings and specific embodiments.

[0023] The embodiment is mainly aimed at the distillation section of rectifying tower cooperating with the reboiler to vaporize acetic anhydride. The function of the reboiler is opposite to that of the condenser. The condenser is used for cooling and condensing, while the reboiler is used for heating and vaporizing. In the operation of the rectifying tower, the reboiler is usually arranged in the distillation section as an auxiliary heater to further enhance the rectifying effect.

[0024] The reboiler is arranged in the distillation section of the rectifying tower. The top end side wall of the distillation section of the rectifying tower is provided with an acetic anhydride vapor inlet, and the bottom end is provided with an acetic anhydride liquid outlet. The acetic anhydride liquid outlet is connected with the feed inlet of the reboiler through a liquid pipe. The acetic anhydride vapor inlet is connected with the discharge outlet of the reboiler.

[0025] The acetic anhydride liquid flows into the reboiler from the bottom of the distillation section through the liquid pipe, is heated and vaporized by the reboiler, and the vaporized acetic anhydride vapor is introduced into the top end of the distillation section through the acetic anhydride vapor inlet to perform the next process in the rectifying tower.

[0026] In production, the position of the reboiler is basically level with that of the distillation section. In this way, the acetic anhydride in the liquid pipe will be cooled and thickened to cause blockage. The circulation of the reboiler is slow and difficult to control. Therefore, a forced circulation pump (i.e. CP in the figure) is arranged on the liquid pipe to improve the circulation efficiency of the reboiler. Figure 1

[0027] In the embodiment, an electromagnetic valve and a sensor are also needed to be arranged to cooperate to realize the stable circulation of the reboiler, which is specifically as follows:

[0028] The liquid pipe is also provided with an electromagnetic valve a.

[0029] The forced circulation pump is arranged on the circulation pipe. The two ends of the circulation pipe are connected to the two sides of the electromagnetic valve a on the liquid pipe. On the circulation pipe, the two sides of the forced circulation pump are also provided with electromagnetic valves b.

[0030] The side wall of the distillation section of the rectifying tower is also provided with a liquid level meter, a thermometer and a pressure gauge, which are respectively used for detecting the liquid level, temperature of the acetic anhydride liquid and the content of the acetic anhydride vapor in the distillation section.

[0031] The pressure gauge is connected with the distillation section through a pressure pipe. The pressure pipe and the communication pipe are respectively provided with electromagnetic valves c and d.

[0032] Two electromagnetic valves e are arranged on the steam inlet pipe of the reboiler. A buffer structure is arranged between the two electromagnetic valves e. The buffer structure includes an adjusting valve, a flow meter and a buffer pipeline.

[0033] The adjusting valve is a three-way combined adjusting valve, which is arranged on the steam inlet pipe near the steam inlet side. The adjusting valve is connected to the steam inlet side of the steam inlet pipe through the buffer pipeline. The flow meter is arranged on the buffer pipeline.

[0034] ​The liquid level meter and the pressure meter can monitor the content of acetic anhydride liquid in the distillation section and the pressure of acetic anhydride vapor, and send the material information of the distillation section to the host computer as sensors.

[0035] In the normal state, the acetic anhydride liquid enters the reboiler from the liquid pipe, and the acetic anhydride vapor generated by the reboiler enters the distillation section from the acetic anhydride vapor inlet. However, due to the gasification of the distillation section itself and the gasification of the reboiler, the pressure value of the acetic anhydride and the liquid level of the acetic anhydride often fluctuate.

[0036] When the pressure value rises significantly, the content of acetic anhydride vapor in the distillation section is too high; the power of the reboiler needs to be reduced to reduce the pressure; at this time, the three-way regulating valve needs to be controlled to adjust the amount of steam, reduce the gasification efficiency of the acetic anhydride, and reduce the content of acetic anhydride vapor generated by the reboiler.

[0037] When the pressure value drops significantly, the content of acetic anhydride vapor in the distillation section is too low, but the liquid level meter shows that the liquid level has not changed significantly and the flow meter shows that the flow has not changed; open the forced circulation pump and the electromagnetic valve b, close the electromagnetic valve a, and strengthen the circulation.

[0038] In addition, the electromagnetic valve, the three-way regulating valve and the forced circulation pump can be used as actuators, the pressure meter, the liquid level meter and the flow meter can be used as sensors, and the host computer can be connected as a control center to realize an automatic control system.

[0039] A drain valve is arranged at the outlet of the cooling liquid of the reboiler in the embodiment, and a drain structure is formed; this structure part is the focus of the patent and is not described in detail as it is common knowledge.

[0040] The parts not described in detail in the embodiment belong to the technology of the person skilled in the art.

[0041] The above is only a preferred embodiment of the utility model, which is intended to further illustrate the utility model, but not to limit it. Any simple replacement according to the above disclosure and the drawings is within the protection scope of the patent.

Claims

1. A retrofit structure for forced circulation of a rectifying column, comprising a rectifying column and a reboiler; characterized by, The reboiler is installed in the stripping section of the rectifying tower; The top end side wall of the stripping section of the rectifying tower is provided with an acetic anhydride vapor inlet, and the bottom end is provided with an acetic anhydride liquid outlet; The acetic anhydride liquid outlet is connected with the feeding port of the reboiler through a liquid pipe; the acetic anhydride vapor inlet is connected with the discharging port of the reboiler; The liquid pipe is further provided with an electromagnetic valve a and a forced circulation structure; the forced circulation structure comprises a forced circulation pump and a circulation pipe, the forced circulation pump is installed on the circulation pipe, and two ends of the circulation pipe are connected on the two sides of the electromagnetic valve a on the liquid pipe; On the circulation pipe, the two sides of the forced circulation pump are further provided with electromagnetic valves b.

2. A retrofit structure for forced circulation of a rectification column according to claim 1, wherein The side wall of the stripping section of the rectifying tower is further provided with a liquid level meter, a thermometer and a pressure gauge, which are respectively used for detecting the liquid level, temperature and content of acetic anhydride vapor in the stripping section; The liquid level meter, the reboiler and the stripping section are located at the same horizontal height; two ports of the liquid level meter are connected with the stripping section through a communication pipe, and the pressure gauge is connected with the stripping section through a pressure pipe; the pressure pipe and the communication pipe are respectively provided with electromagnetic valves c and d.

3. A retrofit structure for forced circulation of a rectification column according to claim 2, wherein Two electromagnetic valves e are arranged on the vapor inlet pipe of the reboiler; a buffer structure is arranged between the two electromagnetic valves e; the buffer structure comprises an adjusting valve, a flow meter and a buffer pipeline; The adjusting valve is a three-way combined adjusting valve, which is installed on the vapor inlet pipe near the vapor inlet side; one branch port of the adjusting valve is connected with the vapor inlet pipe on the far vapor inlet side through the buffer pipeline; the flow meter is installed on the buffer pipeline.

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