Importance Of Process Control

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Before proceeding to the equipment design and the economic analysis, it is necessary to have a look at the process control. The main objective of process control is to produce a product with a certain quality and flow rate. Different operation conditions will result in another product quality and flow rate. Therefore process control is important. In addition, process control is essential for safe operation. Various types of controlling loops are applied to control all the existing valves in the proposed process. These valves can be controlled automatically, since are accessible via software and machines in the control room, as well as manually in case of failures. The purpose of the controllers, the names of the controllers and their operation…show more content…
Finally, conclusions about the process control of the entire process are drawn. 6.1 Feed and reactor In order to find where control is necessary, all process operations are looked upon step by step. After every operation in the process, a decision was made whether or not to implement a controller to check if the operation was successful. The controllers have different operating variables and can be of a feedforward or feed backward nature. All controllers are chosen with the aid of the book Process Dynamics and Control [51]. Fig. 6.1 shows all controllers in the first part of the process. The main controllers are the ones related to the mixing of the feed and the temperature in the reactor. Controlling the temperature in the reactor is of vital importance for the safety as it contains an exothermic reaction. The controllers are explained in the coming paragraphs. Fig. 6.1 Control systems from feed up to reactor. 1. Stream 1 flow: FC01 The stream of flow 1 can fluctuate. A constant flow is important to maintain a constant feed to the reactor with a certain flow rate and a syngas ratio of 2, and thus for the production quality and flow rate. In order to maintain a constant flow a flow controller is added, which measures the…show more content…
6.2. Fig. 6.2 Control system in separation process. 7. Reactor effluent temperature: TC03 The reactor effluent is cooled before it is sent to flash. The flash is very sensitive to temperature changes and thus must be operated in a narrow temperature window. Note that its sensitivity is not regarding the naphtha product, but the sensitivity regards the inerts and water. Hence, a temperature control loop is necessary here. This is also a feedback control loop to adjust flow rate of cooling water. 8. Flash Pressure: PC02 The Flash is very sensitive to pressure changes as well. Different operating conditions in the flash can result in the naphtha evaporating or more impurities in the oily phase. To maintain the desired pressure there is a feed backward controller that operates a valve at the top of the flash to release or increase pressure. 9. Distillation feed flow: FC04 To ensure a constant feed supply to distillation column a flow controller is necessary. The flow rate shall be measured before the valve and a feed-forward controller shall adjust the valve opening or closing according to the fluctuations in the flow. The decanter operates as a small storage tank in this

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