A formaldehyde polymerization production system

Abstract

This invention provides a formaldehyde polymerization prevention system, comprising a formaldehyde absorption tower, a cooler, and a control system. The formaldehyde absorption tower's drain line is connected to an external output line and a return line at the top of the tower. The cooler is connected to the external output line. A dilute formaldehyde conveying mechanism is connected to the return line. A first centrifugal pump is connected to the drain line. The control system and the first centrifugal pump are electrically connected. This invention uses the dilute formaldehyde conveying mechanism to introduce 10%wt dilute formaldehyde waste liquid from the 1,4-butanediol unit into the formaldehyde absorption tower, controlling the formaldehyde solution concentration at 37%wt, allowing it to be directly used by the downstream 1,4-butanediol unit. This prevents the generation of polyoxymethylene (POM) from clogging the packing, cooler, and pipes, thus preventing unit shutdown. Steam condensate is used to heat the 10%wt dilute formaldehyde waste liquid. The heated 10%wt dilute formaldehyde waste liquid then enters the absorption tower and mixes with a 45±3%wt formaldehyde solution, preventing polymerization reactions caused by rapid cooling of the formaldehyde solution within the absorption tower.

Description

Technical Field

[0001] This utility model belongs to the field of formaldehyde production by methanol oxidation and related chemical production technology, specifically relating to a formaldehyde polymerization prevention production system. Background Technology

[0002] Currently, 1,4-butanediol production mainly uses 37% formaldehyde as a raw material. However, due to transportation and storage costs, production companies usually store high-concentration formaldehyde (45±3%wt) as a reserve raw material in storage tanks. During production, it is then prepared into a 37% formaldehyde solution as needed for use as a raw material in downstream 1,4-butanediol units.

[0003] High-concentration formaldehyde solutions often produce white flocculent precipitates when left standing for extended periods or stored below 40°C, transforming into insoluble paraformaldehyde. Due to the polymerization of formaldehyde, its content gradually decreases, causing inconvenience in its use and storage. Furthermore, in actual operation, the downstream 1,4-butanediol unit still produces a significant amount of paraformaldehyde, affecting the normal operation of the absorption tower and product cooler, necessitating periodic shutdowns for maintenance. Utility Model Content

[0004] The purpose of this invention is to provide a formaldehyde polymerization production system that overcomes the aforementioned technical problems in the prior art.

[0005] Therefore, the technical solution provided by this utility model is as follows: A formaldehyde polymerization prevention production system includes a formaldehyde absorption tower, a cooler, and a control system. The formaldehyde absorption tower's drain line is connected to an external output line and a top return line. The cooler is connected to the external output line. A dilute formaldehyde conveying mechanism is connected to the return line. A first centrifugal pump is connected to the drain line. The control system and the first centrifugal pump are electrically connected.

[0006] The dilute formaldehyde conveying mechanism includes a conveying pipeline, a heat exchanger, and an input pipeline. The dilute formaldehyde inlet and outlet of the heat exchanger are connected to the conveying pipeline and the input pipeline, respectively. The heat exchanger is also connected to an inlet hot water pipe and an outlet hot water pipe. The input pipeline is equipped with a temperature sensor and a first solenoid valve, and the hot water outlet pipe is equipped with a second solenoid valve. The temperature sensor, the first solenoid valve, and the second solenoid valve are all connected to the control system via electrical signals.

[0007] The external pipeline is connected to a second centrifugal pump, which is connected to the control system.

[0008] The second centrifugal pump is connected to the product inlet of the cooler, the product outlet of the cooler is connected to the external discharge pipeline, the inlet cold water pipeline of the cooler is connected to the cold water pipeline through the third centrifugal pump, and the outlet cold water pipeline of the cooler is connected to the third centrifugal pump and the external discharge pipeline respectively.

[0009] The cold water pipeline is equipped with a third solenoid valve, and the external transmission pipeline is equipped with a second temperature sensor, a flow transmitter, and a fourth solenoid valve. The second temperature sensor, the flow transmitter, the third solenoid valve, and the fourth solenoid valve are all connected to the control system's electrical signals.

[0010] Steam condensate flows through the hot water inlet pipe.

[0011] The beneficial effects of this utility model are: The formaldehyde polymerization prevention production system provided by this utility model introduces 10%wt dilute formaldehyde waste liquid produced by the 1,4-butanediol unit into the formaldehyde absorption tower through a dilute formaldehyde conveying mechanism. The concentration of formaldehyde solution in the bottom of the formaldehyde absorption tower is controlled at 37%wt. The extracted product can be directly used by the downstream 1,4-butanediol unit, thereby preventing the generation of polyoxymethylene from clogging the packing, cooler and pipeline, thus causing the unit to shut down.

[0012] This formaldehyde polymerization prevention production system uses steam condensate to heat 10%wt dilute formaldehyde waste liquid. The heated 10%wt dilute formaldehyde waste liquid then enters the absorption tower and mixes with a formaldehyde solution with a concentration of 45±3%wt to prevent polymerization reaction caused by rapid cooling of the formaldehyde solution in the absorption tower. The control system controls each centrifugal pump and solenoid valve to automatically regulate the start and stop of the process and the flow rate of steam condensate and cold water. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of one embodiment of the present invention.

[0014] In the diagram: 1. Formaldehyde absorption tower; 2. Cooler; 3. Drainage pipeline; 4. Tower top return pipeline; 5. External transmission pipeline one; 6. First centrifugal pump; 7. Transmission pipeline; 8. Heat exchanger; 9. Input pipeline; 10. Hot water inlet pipe; 11. Hot water outlet pipe; 12. First solenoid valve; 13. Second solenoid valve; 14. Second centrifugal pump; 15. Third centrifugal pump; 16. External transmission pipeline two; 17. Cold water inlet pipeline; 18. Cold water outlet pipeline; 19. External discharge pipeline; 20. Dilute formaldehyde conveying mechanism; 21. Cold water pipeline; 22. Third solenoid valve; 23. Fourth solenoid valve; 24. Filter; 25. Flow transmitter. Detailed Implementation

[0015] The following specific embodiments illustrate the implementation of this utility model. Those skilled in the art can easily understand other advantages and effects of this utility model from the content disclosed in this specification.

[0016] Exemplary embodiments of the present invention are now described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to fully and completely disclose the present invention and to fully convey its scope to those skilled in the art. The terminology used in the exemplary embodiments shown in the drawings is not intended to limit the present invention. In the drawings, the same units / elements are referred to by the same reference numerals.

[0017] Unless otherwise stated, the terms used herein (including technical terms) have their common meaning as understood by one of ordinary skill in the art. Furthermore, it is understood that terms defined in commonly used dictionaries should be understood to have a meaning consistent with the context of their relevant field, and not to be interpreted as having an idealized or overly formal meaning.

[0018] Example 1 This utility model provides a formaldehyde polymerization prevention production system, including a formaldehyde absorption tower 1, a cooler 2, and a control system. The formaldehyde absorption tower 1 has a drain line 3 connected to an external output line 5 and a top return line 4. The cooler 2 is connected to the external output line 5. A dilute formaldehyde conveying mechanism 20 is connected to the return line. A first centrifugal pump 6 is connected to the drain line 3. The control system and the first centrifugal pump 6 are electrically connected.

[0019] Working principle: Formaldehyde absorption tower 1 absorbs the reacted formaldehyde gas to produce formaldehyde solution. The concentration of the extracted formaldehyde solution is controlled to be 45±3%wt using the flow rate of the deionized water at the top of the tower. At the same time, the dilute formaldehyde conveying mechanism 20 introduces the 10%wt dilute formaldehyde waste liquid produced by the 1,4-butanediol unit into formaldehyde absorption tower 1, controlling the formaldehyde solution concentration at the bottom of formaldehyde absorption tower 1 to be 37%wt. It is then discharged through the drain line 3 and enters the external transmission line 5 and the top return line 4 through the first centrifugal pump 6. The external transmission line 5 directly supplies the downstream 1,4-butanediol unit, while the top return line 4 circulates back into formaldehyde absorption tower 1. By adjusting and controlling the flow rates of the deionized water and the 10%wt dilute formaldehyde waste liquid, the formaldehyde solution concentration is stabilized at 37%wt.

[0020] The control system is electrically connected to the first centrifugal pump 6, allowing for control of its start and stop as needed. The 37% wt formaldehyde produced by the formaldehyde absorption tower 1 is filtered through filter 24 before entering the first centrifugal pump 6.

[0021] The formaldehyde-resistant polymerization production system provided by this utility model dilutes a high-concentration formaldehyde solution through a dilute formaldehyde conveying mechanism 20. The extracted product can be directly used in the downstream 1,4-butanediol unit, thereby preventing the generation of polyoxymethylene, which could clog the packing, cooler 2, and pipelines, thus causing the unit to shut down.

[0022] Example 2 Based on Example 1, this example provides a formaldehyde polymerization prevention production system, such as... Figure 1 As shown, the dilute formaldehyde conveying mechanism 20 includes a conveying pipeline 7, a heat exchanger 8, and an input pipeline 9. The dilute formaldehyde inlet and outlet of the heat exchanger 8 are connected to the conveying pipeline 7 and the input pipeline 9, respectively. The heat exchanger 8 is also connected to an inlet hot water pipe 10 and an outlet hot water pipe 11. The input pipeline 9 is equipped with a first solenoid valve 12 and a temperature sensor 1, and the hot water outlet pipe 11 is equipped with a second solenoid valve 13. The temperature sensor 1, the first solenoid valve 12, and the second solenoid valve 13 are all connected to the control system electrical signal.

[0023] like Figure 1 As shown, a 10%wt dilute formaldehyde waste liquid enters the heat exchanger 8 from the waste liquid outlet of the 1,4-butanediol unit through the conveying pipeline 7 to heat the 10%wt dilute formaldehyde waste liquid. After heating, it enters the formaldehyde absorption tower 1 through the input pipeline 9, which solves the problem of large temperature difference between the 10%wt dilute formaldehyde waste liquid and the formaldehyde solution in the formaldehyde absorption tower 1, thereby preventing the polymerization reaction of the formaldehyde solution in the absorption tower caused by rapid cooling.

[0024] A temperature sensor continuously monitors the temperature of the 10%wt dilute formaldehyde waste liquid after heating. When the temperature falls below the set error range, the control system sends signals to the first solenoid valve 12 and the second solenoid valve 13 respectively. The opening of the first solenoid valve 12 is reduced to decrease the flow rate of the dilute formaldehyde waste liquid into the formaldehyde absorption tower 1, while the opening of the second solenoid valve 13 is increased to increase the flow rate of hot water, ensuring that the temperature of the dilute formaldehyde waste liquid meets the set requirements after heating. Conversely, the opening of the first solenoid valve 12 is increased while the opening of the second solenoid valve 13 is reduced.

[0025] Example 3 Based on Example 1, this example provides a formaldehyde polymerization prevention production system, wherein a second centrifugal pump 14 is connected to the external transmission pipeline 5, and the second centrifugal pump 14 is connected to the control system.

[0026] like Figure 1As shown, at the initial stage of process startup, the formaldehyde concentration is unstable and the second centrifugal pump 14 is not started. As the dilute formaldehyde conveying mechanism 20 conveys dilute formaldehyde waste liquid and the formaldehyde solution is refluxed through the top return pipeline 4, when the formaldehyde concentration reaches the standard (37%wt), the control system controls the second centrifugal pump 14 to start, and the 37%wt formaldehyde solution is pumped into the cooler 2 through the second centrifugal pump 14.

[0027] Cooler 2 is used to cool the 37%wt formaldehyde solution to prevent the formaldehyde from forming acid due to high temperature.

[0028] Example 4 Based on Example 1, this example provides a formaldehyde polymerization production system. The second centrifugal pump 14 is connected to the product inlet of the cooler 2, the product outlet of the cooler 2 is connected to the external discharge pipeline 16, the inlet cold water pipeline 17 of the cooler 2 is connected to the cold water pipeline 21 through the third centrifugal pump 15, and the outlet cold water pipeline 18 of the cooler 2 is connected to the third centrifugal pump 15 and the external discharge pipeline 19 respectively.

[0029] like Figure 1 As shown, cold water enters the cooler 2 sequentially through the cold water pipeline 21, the third centrifugal pump 15, and the inlet cold water pipeline 17. Depending on whether the formaldehyde outlet temperature of the product is met, the heat exchange water from the outlet cold water pipeline 18 can be returned to the cooler 2 through the third centrifugal pump 15 or discharged through the outlet pipeline 19.

[0030] Example 5 Based on Example 4, this example provides a formaldehyde polymerization prevention production system. The cold water pipeline 21 is equipped with a third solenoid valve 22, and the external transmission pipeline 26 is equipped with a second temperature sensor, a flow transmitter 25, and a fourth solenoid valve 23. The second temperature sensor, the flow transmitter 25, the third solenoid valve 22, and the fourth solenoid valve 23 are all connected to the control system via electrical signals.

[0031] like Figure 1 As shown, temperature sensor 2 monitors the outlet temperature of the formaldehyde in the product in real time and sends the data to the control system. When the temperature exceeds the set value, the control system sends signals to the third solenoid valve 22 and the fourth solenoid valve 23 respectively, widening the opening of the third solenoid valve 22 and narrowing the opening of the fourth solenoid valve 23 to ensure that the formaldehyde temperature meets the requirements. Simultaneously, flow transmitter 25 monitors the flow rate of the formaldehyde in the product and sends the data to the control system.

[0032] Example 6 Based on Example 2, this example provides a formaldehyde polymerization prevention production system, wherein steam condensate flows through the hot water inlet pipe 10.

[0033] Using steam condensate to heat dilute formaldehyde waste liquid and recovering and utilizing the heat is a green and energy-saving method.

[0034] The above examples are merely illustrative of this utility model and do not constitute a limitation on the scope of protection of this utility model. All designs that are the same as or similar to this utility model are within the scope of protection of this utility model.

Claims

1. A formaldehyde polymerization prevention production system, characterized in that: The system includes a formaldehyde absorption tower, a cooler, and a control system. The formaldehyde absorption tower's drain line is connected to an external output line and a top return line. The cooler is connected to the external output line. A dilute formaldehyde conveying mechanism is connected to the return line. A first centrifugal pump is connected to the drain line. The control system and the first centrifugal pump are electrically connected.

2. The formaldehyde polymerization production system according to claim 1, characterized in that: The dilute formaldehyde conveying mechanism includes a conveying pipeline, a heat exchanger, and an input pipeline. The dilute formaldehyde inlet and outlet of the heat exchanger are connected to the conveying pipeline and the input pipeline, respectively. The heat exchanger is also connected to an inlet hot water pipe and an outlet hot water pipe. The input pipeline is equipped with a temperature sensor and a first solenoid valve, and the hot water outlet pipe is equipped with a second solenoid valve. The temperature sensor, the first solenoid valve, and the second solenoid valve are all connected to the control system via electrical signals.

3. The formaldehyde polymerization production system according to claim 1, characterized in that: A second centrifugal pump is connected to one of the export pipelines.

4. The formaldehyde-resistant polymerization production system according to claim 3, characterized in that: The second centrifugal pump is connected to the product inlet of the cooler, the product outlet of the cooler is connected to the external discharge pipeline, the inlet cold water pipeline of the cooler is connected to the cold water pipeline through the third centrifugal pump, and the outlet cold water pipeline of the cooler is connected to the third centrifugal pump and the external discharge pipeline respectively.

5. The formaldehyde-resistant polymerization production system according to claim 4, characterized in that: The cold water pipeline is equipped with a third solenoid valve, and the external transmission pipeline is equipped with a second temperature sensor, a flow transmitter (25) and a fourth solenoid valve. The second temperature sensor, the flow transmitter, the third solenoid valve and the fourth solenoid valve are all connected to the control system electrical signal.

6. The formaldehyde-resistant polymerization production system according to claim 2, characterized in that: Steam condensate flows through the hot water inlet pipe.

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