Automatic control issues in batch hydrolysis reactions!
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The unit is planning to install a set of closed-tank pressurized hydrolysis reactors; let’s see if automated control can be implemented ? Process: Mix the materials and feed them in – raise the temperature (using jacket steam) to 160°C – stop feeding steam while draining the condensate from the jacket – continue heating the mixture to 166°C – introduce about 11 m³ of cooling water into the jacket (with the pressure inside the reactor being around 0.7 MPa at that time) – maintain the temperature inside the reactor between 170°C and 180°C (with a pressure between 0.7 and 0.85 MPa) for 2 hours (water or steam can be added during this period) – relieve pressure and transfer the material to the crystallization reactor. Note: The reaction begins at 140°C, and it is an exothermic reaction; the higher the temperature and pressure, the faster the reaction proceeds. Therefore, it is crucial to maintain stable temperature and pressure after introducing cooling, otherwise side reactions increase and the product may turn black. Additionally, if the reaction gets out of control, safety accidents can occur. Automatic control primarily maintains the temperature and pressure inside the reactor within the range required by the process by regulating the addition/removal of cold water or the inflow/outflow of steam, based on changes in the pressure and temperature within the reactor. 1. Let’s see if we can submit it for automatic control 2. What other issues should be considered if investing in automatic control? 3. What is the level of automation in your own company or in the chemical companies you have encountered? (Our facility basically has no automatic control systems; at most there are a few interlocks, with most operations being carried out via remote or manual control.)
This can definitely be brought under automatic control; although the process is batch-based, it can be achieved through timing control. Based on the process you described, it is important to ensure stable reaction of the materials; therefore, it is recommended to use the speed or current of the mixing motor for control or monitoring purposes. In fact, I have seen many such factories that are operated manually, with automatic control being applied only during the insulation or heating phase. Achieving full automation isn’t a difficult task either; it’s just that manufacturers generally find the required investment too costly and prefer to rely on manual labor for the work.
Funding isn’t the problem! Because remote manual control is definitely required; on-site instruments such as pneumatic valves and the DCS all have to be purchased! The motor is an inverter-driven motor and can also be controlled by the DCS. It’s not certain that the frequency of the motor can be controlled; the reaction generates a lot of heat. If cooling is not provided in time and the temperature does not drop, both temperature and pressure will rise sharply – the reaction will accelerate rapidly – temperature and pressure will rise again – the reaction will accelerate even more............. It’s a vicious cycle! ! ! The question is, what’s the point of self-control? ? ? ? ? 1. Operators are essential; currently 3 positions are assigned for this task, and there will also be enough people to handle automated control. 2. The manufacturing process is precise, and the automatic control is also of high quality. 3. Other than that, I really can’t think of what the point of self-control is ? ? ? ? This post was last edited by unsuns on 2009-4-20 09:45]
There is some value to it: 1. It’s true that human labor cannot be avoided, but people make mistakes from time to time; machines are more reliable. 2. The control of heat retention and temperature increase is certainly a bit more precise than that done by humans, which will surely lead to better product quality. The scrap rate should be lower, right? Some products have slightly better quality, and their price as well as their reputation make them well worth it, haha. 3. The main reason is safety considerations: The temperature and pressure can change rapidly, so it’s better for the equipment to activate interlocks automatically rather than relying on humans. In the event of an accident, materials can spill out and people can dodge them, but the control systems can still function, which is much better for personal safety. Just a few humble opinions; please forgive me if they’re not good enough.