Control Logic of DCS System to Realize the Whole Process Automation of Propylene Oxide Production?

DCS (Distributed Control System) plays a key role in the automatic control of the whole process of propylene oxide production. Propylene oxide is an important organic chemical raw material, which is widely used in plastics, resins, fibers and other fields. Its production process involves many process links, including propylene oxidation, catalyst reaction and so on. Through the intelligent control logic, DCS system can realize the comprehensive monitoring and optimization of the production process, so as to ensure the product quality and production efficiency. In this paper, the control logic of DCS system in propylene oxide production will be analyzed in depth, and its application and advantages in different process stages will be discussed.

1. DCS System Overview and Propylene Oxide Production Requirements

DCS system is a distributed control system based on computer technology and network communication, which is widely used in chemical, petroleum, pharmaceutical and other fields. Its core is to integrate the various equipment and parameters in the production process through sensors, actuators and controllers to achieve centralized monitoring and decentralized control. Propylene oxide production has higher requirements for automation control, mainly in the following aspects:

1. process complexity the production of propylene oxide involves oxidation reaction, distillation separation and other multi-step processes, each of which requires precise temperature, pressure and flow control.
2. High security requirements: Toxic and harmful substances may be produced in the production process of propylene oxide, which has strict requirements on safety and environmental protection, and requires real-time monitoring and timely response.
3. Efficiency and stability modern production pursues high efficiency and stability. DCS system can reduce energy consumption and increase output by optimizing control strategy.

Control Logic of 2. DCS System in Propylene Oxide Production

the production process of propylene oxide mainly includes raw material preparation, oxidation reaction, distillation separation, product packaging and other links. DCS system in the whole process of data acquisition, logic judgment, equipment control and other important tasks. The following is the specific control logic of DCS system in key links:

1. Raw material preparation and feeding control

before the production of propylene oxide, the DCS system will monitor the liquid level, pressure and other parameters of the raw material tank in real time. In the feeding process, the system automatically adjusts the feeding speed and proportion according to the process parameter setting. For example, when the liquid level of the storage tank is detected to be lower than the preset value, the system will automatically trigger an alarm and suspend the feeding to avoid production interruption due to insufficient materials.

2. Oxidation reaction process control

oxidation reaction is the core link of propylene oxide production, and DCS system plays a key role in this link. The system will collect the temperature, pressure, stirring speed and other parameters in the reactor in real time, and adjust according to the preset control logic. For example:

• temperature control: Ensure that the reaction temperature is maintained within the process requirements by adjusting the cooling water flow or heating device. When the temperature exceeds the set value, the system will automatically start the cooling system to cool down.
• Pressure control: The oxidation reaction will generate a certain pressure. The system ensures that the pressure in the reaction kettle is stable by adjusting the opening of the pressure relief valve.

The DCS system can also dynamically adjust the oxygen flow rate, catalyst addition and other parameters in the reaction process to ensure the reaction efficiency and product purity.

3. Distillation separation and finished product control

distillation is the separation and purification link in the production of propylene oxide, and the DCS system ensures the purity and yield of the product by controlling the temperature, pressure and flow of the distillation tower. For example:

• temperature control: The system automatically adjusts the heating steam flow according to the temperature changes of different layers in the distillation tower to ensure accurate fraction separation.
• Flow Control: By adjusting the opening of the reflux valve and the distillate valve, the precise control of the liquid flow in the distillation tower is realized.

When it is detected that the product purity reaches the set value, the system will automatically switch to the finished product collection stage, and at the same time stop the discharge of non-finished products to reduce material waste.

4. Alarm and chain protection

DCS system also bears the function of alarm and chain protection in the production of propylene oxide. When abnormal parameters are detected, the system will send out an alarm signal in time, and start the corresponding emergency measures according to the preset chain logic. For example:

• chain protection against excessive temperature when the temperature in the reactor exceeds the safety threshold, the system will automatically start the spray system for emergency cooling and close the feed valve to avoid accidents.
• Chain protection of abnormal pressure when the pressure in the reaction kettle is too high, the system will automatically open the safety valve or pressure relief valve to release the excess pressure and ensure the safety of the equipment.

Advantages and Future Development Direction of 3. DCS System

the application of DCS system in the production of propylene oxide not only improves the production efficiency and product quality, but also significantly improves the production safety and environmental protection performance. The following are its main advantages:

1. high precision control DCS system can monitor and adjust the parameters in the production process in real time in milliseconds to ensure the accurate implementation of process indicators.
2. high reliability DCS system adopts redundancy design and fault-tolerant technology, which can quickly switch to the standby system when the key equipment fails to ensure the continuity of production.
3. Intelligent and Scalable modern DCS system supports intelligent control and online optimization functions, and can dynamically adjust control strategies according to production data. At the same time, its open architecture design facilitates subsequent process upgrades and equipment expansion.

In the future, with the development of industrial 4.0 and artificial intelligence technology, DCS system will further evolve in the direction of intelligence and digitization. For example, predictive maintenance based on artificial intelligence can predict equipment failures in advance and reduce downtime; optimization algorithms based on big data analysis can achieve global optimization of the production process and further improve production efficiency.

Conclusion

DCS system in the whole process of propylene oxide production automation control, through intelligent control logic, significantly improve the production efficiency and product quality, to ensure the safety of production. With the continuous progress of technology, DCS system will play a more important role in chemical production, and promote the development of the industry to the direction of intelligent and green.