CN110966519A - Liquid nitrogen gasification system - Google Patents

Abstract

The invention belongs to the field of chemical equipment and discloses a liquid nitrogen gasification system. The system mainly comprises a liquid chlorine steel cylinder, a box type calandria vaporizer and a chlorine buffer tank; the box type calandria vaporizer mainly comprises a box body and calandria pipes, wherein the calandria pipes are of a transverse serpentine pipe structure, a horizontal pipe section of the calandria pipes is located in the box body, a bent pipe section is located outside the box body, and the bent pipe section and the horizontal pipe section are welded outside the box body. The system has simple structure, easy operation, safety and reliability.

Description

Liquid nitrogen gasification system

Technical Field

The invention belongs to the field of chemical equipment, and relates to a liquid nitrogen gasification system.

Background

Liquid nitrogen gasification is the primary process of phosphorus trichloride production, and liquid chlorine is a low-pressure liquefying extremely toxic gas and belongs to hazardous chemicals. The least safe factors are: the raw materials used in the production of the chlor-alkali are industrial salt and water, so that ammonium substances cannot be brought in. When the electrolysis reaction is carried out by using the refined brine containing ammonium ions, the ammonium ions and the chlorine gas which is the electrolysis product are subjected to chemical reaction to generate nitrogen trichloride. The latter enters the liquid chlorine production system along with chlorine gas. When chlorine gas is liquefied, nitrogen trichloride is also liquefied and mixed into the liquid chlorine. When chlorine gas is used, nitrogen trichloride, which is liquefied together with the chlorine gas during the liquefaction and bottling of the chlorine gas, is gradually stored in the vaporization tank. The boiling point of nitrogen trichloride is much higher than that of liquid chlorine (the boiling point of nitrogen trichloride is less than 71 ℃), and the boiling point of liquid chlorine is-34.6 ℃). The explosion hazard content of nitrogen trichloride in the liquid chlorine is 5%. When the liquid chlorine in the vaporization tank is vaporized continuously, the nitrogen trichloride is not vaporized or is not vaporized completely, and the nitrogen trichloride is enriched and accumulated to reach a certain concentration in a long time, and the vaporization tank is likely to explode under a certain condition (such as vibration, sunlight, organic matter action and the like).

Liquid chlorine is mostly discharged from a gas phase of a steel cylinder, the amount of vaporized chlorine of the steel cylinder (particularly in winter) sometimes cannot meet production requirements, and a method of directly heating the steel cylinder is often adopted to accelerate vaporization. The method can cause the temperature of the liquid chlorine to rise sharply, cause overpressure in a liquid chlorine steel cylinder or a buffer tank or melt a safety plug, and cause accidents. Still a considerable number of companies that use chlorine employ steel cylinder liquid phase discharge methods. The liquid chlorine out of the steel cylinder enters a vaporization tank with a heating jacket for vaporization (the vaporization tank belongs to three types of pressure vessels), and the jacket is usually heated by steam or hot water. The liquid chlorine in the tank can be rapidly vaporized by introducing steam, so that the control is difficult; a set of hot water circulating device (such as a hot water tank, a hot water pump and the like) is added when hot water is introduced.

Therefore, how to ensure that the chlorine gas required by the phosphorus trichloride production can be safely and stably ensured during the liquid nitrogen gasification, the accumulation of the nitrogen trichloride in the system is reduced, and the liquid nitrogen gasification process equipment which is safe and reasonable is designed is very important.

Disclosure of Invention

The invention aims to provide a liquid nitrogen gasification system aiming at the defects in the prior art.

The technical scheme of the invention is as follows:

a liquid nitrogen gasification system mainly comprises a liquid chlorine steel cylinder, a box type calandria vaporizer and a chlorine buffer tank; the chlorine liquid steel bottle is connected with the chlorine liquid inlet of the box-type calandria vaporizer, the chlorine outlet of the box-type calandria vaporizer is connected with the chlorine inlet of the chlorine buffer tank, the box-type calandria vaporizer mainly comprises a box body and a calandria, the calandria is of a transverse serpentine tube structure, the horizontal tube section of the calandria serpentine tube structure is located in the box body, the calandria does not have a welding line at the section, the horizontal section is manufactured through a whole pipe, the bent tube section of the calandria serpentine tube structure is outside the box body, and the bent tube section and the horizontal tube section.

And a sewage draining outlet is formed in the bottom of the chlorine buffer tank.

And a safety valve is arranged at the top of the chlorine buffer tank.

A thermometer is arranged on the box body of the box type calandria vaporizer; the box body is communicated with a steam supply pipeline of the steam supply device.

The box-type calandria vaporizer is also provided with a water level gauge, a water inlet, an overflow port and a water outlet at the bottom of the box body of the box-type calandria vaporizer.

And a liquid chlorine flow regulating valve is arranged on the pipeline connecting the liquid chlorine steel cylinder and the box type calandria vaporizer.

The invention has the beneficial effects that:

the calandria in the box body of the box type calandria vaporizer has no welding line, the calandria is made by a leveling pipe, and the welding line is designed at the elbow outside the box body, so that the potential safety hazard of liquid chlorine leakage caused by heating and corrosion of the inner surface and the outer surface of the welding line when the calandria is completely immersed in hot water in the prior art can be avoided.

The invention adopts liquid phase discharging of the liquid chlorine steel cylinder, adopts the box-type calandria gasifier, and adopts hot water to heat the liquid chlorine channel, thereby not only avoiding directly heating the steel cylinder, but also greatly reducing the residual nitrogen trichloride amount in the liquid chlorine channel, and the vaporized nitrogen trichloride is liquefied in the chlorine buffer tank and gathered at the bottom of the buffer tank. Set up the drain in the chlorine buffer tank for regularly discharge nitrogen trichloride raffinate to prevent that nitrogen trichloride from accumulating, be favorable to the continuous production of liquid nitrogen gasification.

In conclusion, the invention has the advantages of simple structure, easy operation, safety and reliability.

Drawings

FIG. 1 is a liquid nitrogen gasification apparatus system for phosphorus trichloride production according to the present invention.

In the figure, the reference numeral 1 is a liquid chlorine steel cylinder, 2 is a box type calandria vaporizer, 2-1 is a box body, 2-2 is a calandria, 3 is a chlorine buffer tank, 4 is a water inlet, 5 is a water outlet, 6 is a thermometer, 7 is a steam supply pipeline, 8 is a water level gauge, 9 is a sewage outlet, 10 is a safety valve, 11 is an on-site pressure gauge, 12 is a temperature display regulating system, 13 is a temperature transmitter, 14 is a pressure display regulating alarm system, 15 is a pressure transmitter, 16 is a liquid chlorine flow regulating valve, 17 is an overflow port, 18 is a temperature detector, 19 is a pneumatic regulating valve, 20 is a liquid chlorine safety valve, and 21 is an electronic scale.

Detailed Description

The invention is further described below with reference to the figures and examples.

Example 1

A liquid nitrogen gasification system mainly comprises a liquid chlorine steel cylinder 1, a box type calandria vaporizer 2 and a chlorine buffer tank 3; the chlorine liquid steel bottle 1 is connected with a chlorine liquid inlet of the box type calandria vaporizer 2, a chlorine gas outlet of the box type calandria vaporizer 2 is connected with a chlorine gas inlet of the chlorine buffer tank 3, the liquid chlorine steel bottle 1 is connected with the box type calandria vaporizer 2, the box type calandria vaporizer 2 is connected with the chlorine buffer tank 3 through pipelines, the box type calandria vaporizer 2 mainly comprises a box body 2-1 and a calandria 2-2, the calandria 2-2 is of a transverse serpentine tube structure, a horizontal tube section of the calandria 2-2 serpentine tube structure is located in the box body 2-1, the calandria at the section has no welding seam, the horizontal section is manufactured by a whole tube, a bent tube section of the calandria 2-2 serpentine tube structure is outside the box body 2-1, and the bent tube section and the horizontal tube. The welding seam of the calandria is designed at the elbow outside the carriage body.

The liquid chlorine cylinder 1 is placed on an electronic scale 21, and the remaining amount of liquid chlorine in the liquid chlorine cylinder 1 is monitored.

The bottom of the chlorine buffer tank 3 is provided with a sewage outlet 9. The drain 9 discharges residual liquid periodically to prevent nitrogen chloride from accumulating.

The top of the chlorine buffer tank 3 is provided with a safety valve 10 and a site pressure gauge 11. Under abnormal conditions, the safety valve jumps when the system is overpressurized and can not automatically release pressure, and leaked chlorine is introduced into an accident alkali destruction tower by a pipeline to be treated so as to avoid overpressure explosion caused by automatic pressure release.

The box type calandria vaporizer 2 is provided with a thermometer 6 on the box body 2-1; the cabinet 2-1 is communicated with a steam supply pipe 7 connected to a steam supply apparatus. The temperature of the hot water in the box is controlled between 55 ℃ and 58 ℃.

The box type calandria carburetor 2 is also provided with a water level gauge 8, a water inlet 4, an overflow port 17 for adjusting the water level in the box, and a water outlet 5 at the bottom of the box body of the box type calandria carburetor 2. The device is used for discharging residual liquid regularly to avoid scale accumulation.

The pipeline connecting the liquid chlorine steel cylinder 1 and the box type calandria vaporizer 2 is provided with a liquid chlorine flow regulating valve 16. For regulating the flow of the liquid chlorine flowing from the liquid chlorine cylinder 1 to the box type calandria vaporizer 2.

The box type calandria vaporizer 2 is also provided with an automatic temperature regulation system which mainly comprises a temperature detector 18 positioned in the box body of the box type calandria vaporizer, a temperature display regulation system 12 positioned outside the box body and a temperature transmitter 13; the temperature detector 18 is connected with the temperature display and regulation system 12, transmits the temperature in the box to the temperature display and regulation system 12, when the temperature in the box is lower than or higher than a set value, the temperature display and regulation system 12 transmits a signal to the temperature transmitter 13, and the temperature transmitter 13 controls the on-off of a pneumatic regulating valve 19 of the steam supply device.

The system can also be provided with a pressure alarm regulating system which mainly comprises a pressure transmitter 15, a pressure display regulating alarm system 14 and a liquid chlorine valve 21 positioned on a pipeline connecting the liquid chlorine steel cylinder 1 and the box-type calandria vaporizer 2, on one hand, an operation chamber can give an alarm when the chlorine buffer tank 3 is in overpressure, and on the other hand, the flow of the liquid chlorine out of the steel cylinder can be automatically regulated by the pressure feedback on the buffer tank according to the process requirements of the post-system. One end of the pressure transmitter 15 is connected with the chlorine buffer tank 3, and transmits a pressure signal of the collected chlorine buffer tank 3 to the pressure display regulation alarm system 14, when the chlorine buffer tank 3 is in overpressure, the pressure display regulation alarm system 14 gives an alarm and controls the liquid chlorine safety valve 20 to be closed.

All pressure gauges, thermometers and safety valves on equipment and pipelines in the system are in an isolated mode. To prevent chlorine corrosion and inaccurate measurement.

The liquid chlorine steel cylinder 1 adopts a copper tube which is subjected to annealing treatment for external connection and can be used after being qualified through a pressure resistance test. The adopted carburettor, pipeline, buffer tank, etc. should meet the requirements of the supervision regulations of pressure vessel safety technology.

Claims (4)

1. A liquid nitrogen gasification system mainly comprises a liquid chlorine steel cylinder (1), a box-type calandria vaporizer (2) and a chlorine buffer tank (3); the chlorine liquid steel bottle (1) is connected with a chlorine liquid inlet of the box-type calandria vaporizer (2), a chlorine gas outlet of the box-type calandria vaporizer (2) is connected with a chlorine gas inlet of the chlorine buffer tank (3), the box-type calandria vaporizer (2) mainly comprises a box body (2-1) and a calandria (2-2), the calandria (2-2) is of a transverse serpentine tube structure, and the chlorine liquid steel bottle is characterized in that a horizontal tube section of the calandria (2-2) serpentine tube structure is located in the box body (2-1), a bent tube section of the calandria (2-2) serpentine tube structure is located outside the box body (2-1), and the bent tube section and the horizontal tube section are welded outside the box body (2-1).

2. The liquid nitrogen gasification device system according to claim 1, wherein a sewage draining outlet (9) is arranged at the bottom of the chlorine buffer tank (3).

3. The liquid nitrogen gasification device system according to claim 1, wherein a safety valve (10) is provided on the top of the chlorine buffer tank (3).

4. The liquid nitrogen gasification device system according to claim 1, wherein the tank (2-1) of the tank type calandria vaporizer (2) is provided with a thermometer (6); the box body (2-1) is communicated with a steam supply pipeline (7) of the steam supply device.

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