Stable storage device for trioxymethylene

Abstract

The utility model belongs to the technical field of trioxymethylene production process, and particularly discloses a trioxymethylene stable storage device which comprises a storage tank, a feeding pipeline, a conveying unit and a cascade control system, the feeding pipeline is communicated with the storage tank, the storage tank is communicated with a first tail gas pipeline, the first tail gas pipeline is communicated with a first nitrogen pipeline, and the first nitrogen pipeline is communicated with a second nitrogen pipeline. The first nitrogen pipeline is communicated with a first tail gas pipeline, the first tail gas pipeline is communicated with a tail gas absorption tower, the first nitrogen pipeline and the first tail gas pipeline are respectively connected with a teletransmission pressure gauge and a first regulating valve, and the teletransmission pressure gauge and the first regulating valve are respectively in communication connection with a cascade control system; the outer wall of the storage tank is connected with a heat tracing unit used for heating the storage tank. According to the trioxymethylene storage tank, produced trioxymethylene is input into the storage tank through the feeding pipeline, so that the trioxymethylene storage tank can be uniformly heated in the storage process, the stopping frequency in the production process of the trioxymethylene is effectively reduced, and the production continuity of the trioxymethylene is ensured.

Description

Technical Field

[0001] The utility model relates to the technical field of trioxymethylene production process, in particular to a stable storage device for trioxymethylene. Background Art

[0002] In the production process of polyoxymethylene, the monomers of copolymer polyoxymethylene are composed of trioxane and dioxolane. Trioxane, also known as trioxane, is an organic compound, mainly used as an intermediate of engineering plastic polyoxymethylene and other chemicals, and can also be used as a disinfectant and a colorless and flameless fuel.

[0003] At present, the product storage method of tripolyformaldehyde production enterprises is to use storage tanks, and use 95℃ hot water coils to heat the bottom of the tanks. The top of the tanks includes feed pipelines, reflux pipelines, exhaust pipelines, nitrogen sealing pipelines, remote transmission diaphragm box pressure gauges, remote transmission wave radar level gauges, etc.

[0004] Since trioxymethylene is active in nature, has a melting point of 64°C, is easy to self-polymerize, and is easy to volatilize and decompose under high temperature conditions, the current storage of trioxymethylene has caused great difficulties for various companies.

[0005] When the storage temperature of trioxymethylene is below 80℃ for a long time, trioxymethylene will slowly form polymers, scale or crystallize, thus blocking pipelines, equipment and instruments, affecting the continuity of trioxymethylene production. If the temperature is too high, trioxymethylene will volatilize, blocking the tail gas pipeline on the top of the storage tank, the membrane box of the remote instrument, etc., resulting in inaccurate display of the tank pressure and liquid level. Monitoring errors may even cause safety accidents, posing a major safety hazard. Utility Model Content

[0006] The utility model aims to provide a stable storage device for trioxymethylene to solve the problem that the temperature of the existing trioxymethylene is unstable during temporary storage, which easily leads to the scaling of trioxymethylene to block pipelines, storage tanks, instruments and other equipment, or the decomposition and volatilization blocks the instrument diaphragm box and causes inaccurate measurement.

[0007] To achieve the above-mentioned purpose, the basic scheme provided by the utility model is: a stable storage device for trioxymethylene, comprising a storage tank, a feed pipeline, a conveying unit for discharging and a cascade control system, wherein the feed pipeline is connected to the storage tank, the top of the storage tank is connected to a first exhaust gas pipeline, the first exhaust gas pipeline is connected to a first nitrogen pipeline, the first exhaust gas pipeline is connected to an exhaust gas absorption tower, the first nitrogen pipeline and the first exhaust gas pipeline are respectively connected to a remote pressure gauge and a first regulating valve, the remote pressure gauge and the first regulating valve are respectively communicated with the cascade control system, the storage tank is connected to two remote pressure differential level gauges, and the outer wall of the storage tank is connected to a heating unit for heating the storage tank.

[0008] The principle and beneficial effect of the utility model are as follows: the utility model inputs the produced trioxymethylene into the storage tank through the feed pipeline, inputs nitrogen into the storage tank through the first nitrogen pipeline to realize the nitrogen sealing operation, so that the top of the storage tank and the vicinity are filled with nitrogen, thereby playing a role in inhibiting the decomposition and volatilization of trioxymethylene; the storage tank is heated by the heating unit, which reduces the volatilization of trioxymethylene and the scaling during the storage process, and also reduces the decomposition of trioxymethylene; the remote pressure gauge and the first regulating valve are controlled by the cascade control system to control the storage tank pressure under the condition of 30KPa, further reducing the trioxymethylene entering the first tail gas pipeline and thus blocking the first tail gas pipeline. The trioxymethylene storage tank can be evenly heated during the storage process, effectively reducing the number of stops during the polyoxymethylene production process, thereby ensuring the continuity of polyoxymethylene production.

[0009] Solution 2, which is the preferred basic solution, the delivery unit includes a discharge pipeline and a delivery pump, the discharge pipeline is connected to the bottom of the storage tank, a filter is connected between the inlet of the delivery pump of the discharge pipeline, a delivery pipeline is connected between the outlet of the delivery pump and the post-processing unit and the polymerization unit, and a shower valve is connected to the inlet and outlet pipelines of the filter respectively;

[0010] Start the delivery pump, and when the liquid level of trioxymethylene in the storage tank reaches 10% of the total volume of the storage tank, open the valve on the delivery pipeline to deliver the trioxymethylene to the polymerization unit or other post-processing units.

[0011] Option three is a preferred option of option two. A first reflux pipeline is connected between the feed pipeline and the storage tank, and a second regulating valve is connected to the first reflux pipeline. When the liquid level in the storage tank reaches 5% of the total volume of the storage tank, the second regulating valve is opened and the valve on the feed pipeline is kept closed. After trioxymethylene comes out of the discharge pipeline, it is pumped back into the storage tank by the delivery pump to form a cycle, thereby stabilizing the pressure in the delivery pump and the discharge pipeline.

[0012] Solution 4, which is the preferred solution of the basic solution, the heating unit is an external heating coil, a water supply pipeline and a return water pipeline, the external heating coil is wound and connected to the outer wall of the storage tank, the water supply pipeline and the return water pipeline are respectively connected to the external heating coil, and the outer wall of the storage tank is coated with thermal conductive paste;

[0013] By wrapping an external heating coil around the storage tank, it helps to heat and insulate the tank, so that the storage temperature of trioxymethylene is stabilized at around 80°C, reducing the volatilization of trioxymethylene and scaling during storage, and also reducing the decomposition of trioxymethylene. At the same time, compared with the conventional full-jacket method for heating the storage tank, it avoids to a certain extent the problems of large investment in full-jacketed tanks, high manufacturing requirements, and uneven insulation caused by bias flow in the blind area of ​​heating of the interface pipes; by applying thermal conductive putty on the outer wall of the storage tank, it helps to ensure that the tank is heated evenly.

[0014] Scheme 5, which is a preferred embodiment of Scheme 4, each of the two interfaces of the remote differential pressure level gauge connected to the storage tank is respectively connected to a purge ring, each of the purge rings is connected to the storage tank, and each of the purge rings is connected to a second nitrogen pipeline;

[0015] By setting a purge ring at the measuring point of the storage tank on the remote pressure differential level gauge and using the purge ring to purge the remote pressure differential level gauge through the second nitrogen pipeline, it is avoided that the trioxymethylene structure blocks the membrane box and thus affects the measurement effect.

[0016] Scheme 6, which is a preferred embodiment of Scheme 5, the top of the storage tank is connected to a second tail gas pipeline, the second tail gas pipeline is connected to a tail gas absorption tower, a bursting disc and a safety valve are connected to the second tail gas pipeline, and the bursting disc and the safety valve are connected in series;

[0017] The tripping pressure of the safety valve is 100KPa. When the pressure in the storage tank exceeds 30KPa and reaches 100KPa, the bursting disc will explode. After the bursting disc explodes, the safety valve will trip, and the gas in the storage tank will enter the exhaust gas absorption tower from the second exhaust gas pipeline.

[0018] Option 7, which is a preferred embodiment of Option 3, a second reflux pipeline is connected between the feed pipeline and the storage tank; by setting the second reflux pipeline, the second reflux pipeline is used as a reflux pipeline between the polymerization unit or other post-processing unit and the storage tank, so as to prevent the polymerization unit or the post-processing unit from stopping the feed pump when it is in a parking state;

[0019] If the subsequent process is stopped and the delivery pump is turned off, the residual trioxymethylene in the discharge pipeline from the delivery pump inlet to the storage tank will scale or crystallize and block the discharge pipeline after a long period of cooling. Therefore, a second reflux pipeline is set to ensure the smoothness of the process cycle.

[0020] Option 8, which is a preferred option of Option 5, is that each of the purge rings is provided with a heating jacket on the outside, and each heating jacket is filled with 135°C steam; by providing a heating jacket, the nitrogen passed into the purge ring is heated by steam, thereby ensuring that the temperature at the measuring point of the remote pressure differential level gauge will not cause the trioxyformaldehyde structure to block the diaphragm box of the instrument and cause inaccurate measurement.

[0021] Option nine, which is the preferred option of the basic option, is that the storage tank is connected to two thermometers; the temperature in the storage tank is detected in real time by the thermometers, so that the temperature of the trioxymethylene can be stabilized at 80-85°C without volatilization or crystallization in large quantities.

[0022] Option 10 is a preferred option of Option 2, wherein the filter is a basket filter; by using the basket filter to filter the residue of trioxymethylene, the filtering accuracy is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The utility model is a schematic diagram of the main structure of a stable storage device for trioxymethylene. DETAILED DESCRIPTION

[0024] The utility model is further described in detail below through specific implementation methods:

[0025] The figure marks in the drawings of the specification include: 1. storage tank; 2. feed pipeline; 3. first nitrogen pipeline; 4. second nitrogen pipeline; 5. discharge pipeline; 6. delivery pump; 7. filter; 8. feed pipeline; 9. external heating coil; 10. water supply pipeline; 11. return pipeline; 12. first reflux pipeline; 13. second reflux pipeline; 14. remote pressure gauge; 15. remote differential pressure level gauge; 16. shower valve; 17. purge ring; 18. first exhaust pipeline; 19. second exhaust pipeline; 20. bursting disc; 21. safety valve; 22. first regulating valve; 23. thermometer; 24. second regulating valve.

[0026] like Figure 1 As shown: a stable storage device for trioxymethylene, comprising a storage tank 1, a feed pipeline 2, a conveying unit and a cascade control system, wherein the feed pipeline 2 is arranged near the bottom of the storage tank 1 and is connected to the storage tank 1, the top of the storage tank 1 is connected to a first tail gas pipeline 18 and a second tail gas pipeline 19, the first tail gas pipeline 18 is connected to a first nitrogen pipeline 3, the first nitrogen pipeline 3 and the first tail gas pipeline 18 are respectively connected to a remote pressure gauge 14 and a first regulating valve 22, the remote pressure gauge 14 and the first regulating valve 22 are respectively connected to the cascade control system, and each remote pressure gauge 14 is provided with a sleeve on the outside There is a hot water jacket, and the first regulating valve 22 is controlled according to the pressure value detected by the remote pressure gauge 14 and through the cascade control system, so that the pressure in the storage tank 1 is maintained at 30KPa; the second tail gas pipeline 19 is connected with a bursting disc 20 and a safety valve 21, and the bursting disc 20 and the safety valve 21 are connected in series, that is, the safety valve 21 opens when the bursting disc 20 explodes; the first tail gas pipeline 18 and the second tail gas pipeline 19 are respectively connected to the tail gas absorption tower, and the first tail gas pipeline 18 and the second tail gas pipeline 19 are respectively connected with a hot water jacket to avoid blockage of the first tail gas pipeline 18 and the second tail gas pipeline 19.

[0027] The storage tank 1 is fixedly connected to two remote differential pressure level gauges 15, and the two remote differential pressure level gauges 15 are respectively bolted with purge rings 17. A second nitrogen pipeline 4 is provided on one side of the storage tank 1. Each purge ring 17 is connected to the second nitrogen pipeline 4, and each purge ring 17 is also connected to the storage tank 1. Each of the purge rings 17 is provided with a heating jacket, and each heating jacket adopts a 2S steam type jacket. Each heating jacket is passed through 135°C steam for heating nitrogen, and the outside of each remote differential pressure level gauge 15 is provided with a hot water jacket; the outer wall of the storage tank 1 is connected to a heating unit, and the heating unit is an external heating coil 9, a water supply pipeline 10 and a return water Pipeline 11, the external heating coil 9 is wrapped around the outer wall of the storage tank 1, the water supply pipeline 10 and the return water pipeline 11 are respectively connected to the external heating coil 9, and the other ends of the water supply pipeline 10 and the return water pipeline 11 are respectively connected to the hot water storage tank in the factory, the water supply pipeline 10 is arranged close to the bottom of the storage tank 1, and the return water pipeline 11 is arranged close to the top of the storage tank 1. The winding distance of the external heating coil 9 does not exceed 50 cm, and the storage tank 1 is wrapped with an internal heating coil. The heating unit can also use a full jacket to wrap the storage tank 1 for heating and insulation. When using the full jacket for heating, 80°C hot water is passed through the full jacket; the outer wall of the storage tank 1 is coated with thermal conductive putty to facilitate uniform heating of the storage tank 1.

[0028] The conveying unit includes a discharge pipeline 5 and a conveying pump 6. The discharge pipeline 5 is connected to the bottom of the storage tank 1, and the discharge pipeline 5 is connected to the inlet of the conveying pump 6. A filter 7 is provided on the side close to the inlet of the conveying pump 6. The filter 7 adopts a basket filter. The pipelines at the inlet and outlet of the filter 7 are respectively connected to a shower valve 16. A bypass pipeline is provided on one side of the filter 7. The bypass pipeline is connected to a filter 7 of the same model for switching during maintenance. The outlet of the conveying pump 6 is connected to a conveying pipeline 8, which is connected to a polymerization unit or other post-processing units; the inlet and outlet of the conveying pump 6 are respectively provided with a hot water jacket.

[0029] The feed pipeline 8 is connected to the first return pipeline 12 and the second return pipeline 13 respectively, the first return pipeline 12 is connected to the second regulating valve 24, the feed pipeline 8 and the second return pipeline 13 are both connected to valves, and the first return pipeline 12 and the second return pipeline 13 are respectively connected to the storage tank 1. Two thermometers 23 are provided at the bottom of the storage tank 1, one of which is a conventional real-time display thermometer 23, and the other thermometer 23 is a remote transmission thermometer and is connected to the central control room for remote monitoring; the internal heating coil of the storage tank 1, the external heating coil 9 and each hot water jacket are all connected with 80°C hot water.

[0030] The implementation method of this embodiment is: before the device is operated, first confirm that each hot water jacket, the internal heating coil and the external heating coil 9 are all stably supplied with hot water at 80°C, and that the heating jacket outside the purge ring 17 is supplied with stable steam at 135°C, observe the remote pressure gauge 14, and maintain the pressure of the storage tank 1 at 30KPa.

[0031] After the device is put into use, the first regulating valve 22 on the first nitrogen pipeline 3 and the first tail gas pipeline 18 is opened, and the produced trioxymethylene is introduced into the storage tank 1 through the feed pipeline 2, and nitrogen is introduced into the purge ring 17 through the second nitrogen pipeline 4.

[0032] Observe the liquid level of the storage tank 1 measured by two remote differential pressure level gauges 15. When the liquid level of trioxymethylene in the storage tank 1 reaches 5% of the storage tank 1, open the second regulating valve 25 and keep the valve on the feed pipeline 8 closed, start the delivery pump 6, and the trioxymethylene enters the delivery pump 6 and circulates in the first reflux pipeline 12; when the liquid level of trioxymethylene in the storage tank 1 reaches 10%, open the valves on the feed pipeline 8 and the second reflux pipeline 13 to transport the trioxymethylene to the polymerization unit and other post-processing units.

[0033] Observe the displays of the two remote differential pressure level gauges 15 and the two pressure gauges at the same time, and judge the accuracy of the measurement after comparison. If there is no difference in the measurement results, it proves that the trioxymethylene has not seriously volatilized and scaled to block the pipeline or instrument.

[0034] The above is only an embodiment of the utility model, and the common knowledge such as the known specific structure and characteristics in the scheme is not described in detail here. It should be pointed out that for those skilled in the art, several deformations and improvements can be made without departing from the structure of the utility model, which should also be regarded as the protection scope of the utility model, and these will not affect the effect of the implementation of the utility model and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A stable storage device for trioxymethylene, characterized in that: The invention comprises a storage tank (1), a feed pipeline (2), a conveying unit for discharging materials, and a cascade control system, wherein the feed pipeline (2) is connected to the storage tank (1), the top of the storage tank (1) is connected to a first tail gas pipeline (18), the first tail gas pipeline (18) is connected to a tail gas absorption tower, the first tail gas pipeline (18) is connected to a first nitrogen pipeline (3), the first nitrogen pipeline (3) and the first tail gas pipeline (18) are respectively connected to a remote pressure gauge (14) and a first regulating valve (22), the remote pressure gauge (14) and the first regulating valve (22) are respectively connected to the cascade control system for communication, the storage tank (1) is connected to two remote differential pressure level gauges (15), and the outer wall of the storage tank (1) is connected to a heating unit for heating the storage tank (1).

2. A stable storage device for trioxymethylene according to claim 1, characterized in that: The conveying unit comprises a discharge pipeline (5) and a conveying pump (6); the discharge pipeline (5) is connected to the bottom of the storage tank (1); a filter (7) is connected between the inlet of the discharge pipeline (5) and the conveying pump (6); a conveying pipeline (8) is connected between the outlet of the conveying pump (6) and the post-processing unit and the polymerization unit; and a shower valve (16) is respectively connected to the inlet and outlet pipelines of the filter (7).

3. A stable storage device for trioxymethylene according to claim 2, characterized in that: A first return pipeline (12) is connected between the material delivery pipeline (8) and the storage tank (1), and a second regulating valve (24) is connected to the first return pipeline (12).

4. A stable storage device for trioxymethylene according to claim 1, characterized in that: The heating unit comprises an external heating coil (9), a water supply pipeline (10) and a water return pipeline (11); the external heating coil (9) is wound and connected to the outer wall of the storage tank (1); the water supply pipeline (10) and the water return pipeline (11) are respectively connected to the external heating coil (9); and the outer wall of the storage tank (1) is coated with heat-conducting paste.

5. A stable storage device for trioxymethylene according to claim 4, characterized in that: The two interfaces connecting each remote differential pressure level gauge (15) and the storage tank (1) are respectively connected to a purge ring (17), each purge ring (17) is in communication with the storage tank (1), and each purge ring (17) is in communication with a second nitrogen pipeline (4).

6. A stable storage device for trioxymethylene according to claim 5, characterized in that: The top of the storage tank (1) is connected to a second tail gas pipeline (19), the second tail gas pipeline (19) is connected to a tail gas absorption tower, a bursting disc (20) and a safety valve (21) are connected to the second tail gas pipeline (19), and the bursting disc (20) and the safety valve (21) are connected in series.

7. A stable storage device for trioxymethylene according to claim 3, characterized in that: A second reflux pipeline (13) is connected between the material delivery pipeline (8) and the storage tank (1).

8. The stable storage device of trioxymethylene according to claim 5, characterized in that: The outside of each purge ring (17) is provided with a heating jacket, and each heating jacket is filled with steam at 135°C.

9. The stable storage device of trioxymethylene according to claim 1, characterized in that: The storage tank (1) is connected to two temperature gauges (23).

10. The stable storage device of trioxymethylene according to claim 2, characterized in that: The filter (7) is a basket filter (7).

Images