How can you use process control to avoid product contamination?

1 Process control basics

Process control is the application of engineering principles and techniques to design, operate, and maintain a process system that meets the desired specifications and objectives. It involves measuring and manipulating process variables, such as temperature, pressure, flow, concentration, pH, or composition, to achieve a set point or a target value. Process control can be classified into two main types: feedback control and feedforward control. Feedback control uses the output of the process to adjust the input, while feedforward control uses the input or the disturbance to adjust the output. Both types of control can help you avoid product contamination by correcting deviations or disturbances that may affect the product quality.

2 Process control methods

In chemical production systems, there are several methods for implementing process control. PID control is a feedback control method that uses proportional, integral, and derivative actions to adjust the input based on the error between the output and set point. This can provide fast and accurate response to changes in the process and reduce steady-state error, however it can also cause oscillations, overshoots, or instability if not tuned properly. Model predictive control (MPC) is a feedforward control method that uses a mathematical model of the process to predict the future behavior of the output and adjust the input accordingly. This allows for complex and nonlinear processes, multiple inputs and outputs, and constraints on the process variables; however it may require high computational power, accurate models, and reliable measurements. Fuzzy logic control (FLC) is a feedback control method that uses linguistic rules and fuzzy sets to adjust the input based on the degree of membership of the output to the set point. FLC can deal with uncertainty, ambiguity, and imprecision in the process while providing smooth and robust control; however it may require expert knowledge, subjective interpretation, and large rule bases.

3 Process control applications

Process control can be applied to various stages and aspects of chemical production to avoid product contamination. For example, reactor control involves controlling the temperature, pressure, flow, concentration, and conversion of the reactants and products in a chemical reactor to prevent runaway reactions, side reactions, or incomplete reactions that may produce unwanted or harmful substances in the product stream. Separation control is also important for controlling the separation of the product from the by-products, impurities, or solvents in a separation unit. This can ensure the purity, recovery, and yield of the product and avoid cross-contamination or carryover of undesired components. Lastly, quality control is necessary for controlling the physical, chemical, and biological properties of the product to verify compliance with specifications, standards, and regulations. This can help to avoid any defects, deviations, or variations that may affect the product performance or safety.

4 Process control challenges

Process control is not a simple or straightforward task, and faces many challenges and difficulties that can compromise its effectiveness or reliability. Process dynamics, which refer to changes in the process behavior over time due to the nonlinear, time-varying, or stochastic nature of the process, can make the process hard to model, predict, or control and require adaptive or robust control methods. Additionally, process disturbances from external or internal factors can cause the process to deviate from the set point or target value and require fast or preventive control actions. Lastly, process constraints such as minimum or maximum values, ranges, or ratios can affect the feasibility, optimality, or stability of the process and require coordinated or constrained control methods.

5 Process control benefits

Process control can be highly beneficial for chemical engineers and chemical products, providing a range of advantages such as improved product quality, enhanced product safety, and increased product profitability. Process control can ensure the consistency, uniformity, and accuracy of the product properties while preventing the formation, accumulation, or transmission of contaminants, impurities, or toxins that may pose health or environmental risks. Additionally, process control can optimize process efficiency, productivity, and performance while reducing process waste, energy, and cost.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?