That expert provided some knowledge on the production process of polyoxymethylene as well as information related to the equipment used

Polyoxymethylene can be divided into copolymerized polyoxymethylene and homopolymerized polyoxymethylene; DuPont in the United States produces homopolymerized polyoxymethylene, while most domestic manufacturers produce copolymerized polyoxymethylene. The specific manufacturing processes are kept confidential; you could work for a company that produces polyoxymethylene – maybe you can get some information there

The dilute formaldehyde aqueous solution produced in the vacuum concentration step of process S1 is sent to the methanol recovery tower 1aCS21 via the methanol column feed heater 1aES22, using the dilute formaldehyde circulation pumps 1aPS14A,B. The formalin aqueous solution is heated to 96°C in the methanol column feed heater 1aES22, using the heat from the formalin aqueous solution containing a small amount of methanol, which is discharged from the bottom of the methanol recovery tower 1aCS21. The purpose of this tower is to remove residual methanol from aqueous dilute formaldehyde solutions. The aqueous dilute formaldehyde solution supplied to the tower is controlled by a flow regulator 1aFRCS115. The methanol column reboiler 1aES21 mentioned above is heated with 0.1 MPa(G) steam. The steam intake volume is controlled by the flow regulator 1aFRCS201. The vapor leaving the tower is condensed in the methanol condenser 1aES23. The final methanol condensate, at 58°C and containing approximately 76% wt of methanol, flows by gravity to the methanol reflux tank 1aVS22. This stream of methanol is divided into two streams and transported via the methanol recovery pumps 1aPS21A, B. One stream returns to the methanol recovery tower 1aCS21 as reflux, while another is sent to the T2 – light components separation process. The backflow rate is controlled by the flow regulator 1aFRCS202, which is regulated based on the temperature output signal from the 31st tray of the tower. The distillate flow rate from methanol reflux tank 1aVS22 is controlled by the level control loop 1aLICAHL202. The aqueous formaldehyde solution, which is the bottom product from methanol recovery tower 1aCS21, is heated by the methanol tower feed heater 1aES22 and sent to the dilute formaldehyde storage tank 1aVS23. The formaldehyde aqueous solution containing a small amount of methanol is cooled from 103°C to 67°C in the methanol tower feed heater 1aES22. The dilute formaldehyde storage tank 1aVS23 also collects the following formalin aqueous solutions: – Dilute formalin aqueous solution from Tower 3 for formalin absorption 1aCS33 (containing approximately 3% wt of CH2O) ； -A dilute formaldehyde aqueous solution from Unit Y (containing approximately 2% wt of CH2O). Together with these materials, the final liquid contains approximately 13% wt of CH2O, and it is sent to the pressurized distillation column 1aCS31 via the neutralization feed pump 1aPS22A,B. Since the dilute formaldehyde aqueous solution contains some acidic compounds, mainly formic acid, it is neutralized using a dilute sodium hydroxide solution. The NaOH solution from outside the boundary area (37% wt) is sent to the alkali metering tank 1aVS21, where it is diluted to 4% wt using make-up deionized water, and then delivered by gravity to the dilute alkali storage tank 1aVS24. From this container, the dilute alkali solution is sent to the inlets A and B of 1aPS22A via the dilute alkali pump 1aPS23A, and to the inlets A and B of the pressurized reflux pump 1aPS31A via the dilute alkali pump 1aPS23B. The pump flow rate mentioned earlier is controlled by frequency converters equipped with pH meters; the pH meters are 1aARCSAHLS211 for 1aPS23A and 1aARCSAHLS301 for 1aPS23B. To prevent the pH value from rising above the allowable range, the system is protected by interlocks 1aISS211 and 1aISS301, which stop the functioning metering pumps to avoid high pH levels.