Chemical Engineer Interview Questions

Interviewer: Good morning, can you introduce yourself and tell us about your background in chemical engineering?

Candidate: Good morning. My name is John Smith and I have a Bachelor of Science in Chemical Engineering from the University of Michigan. I’ve also completed internships with a few companies where I worked on projects involving process design and optimization.

Interviewer: Can you describe your experience with process design and development?

Candidate: Sure. In my previous role, I was responsible for designing and developing processes for the production of pharmaceuticals. I have experience in a range of areas, including material handling, equipment selection, and process automation.

Interviewer: Can you tell us about a time where you implemented a solution that improved an existing process?

Candidate: In my previous role, we had an issue with our reactor being unable to maintain a consistent temperature. I worked with the team to identify the root cause and implemented a new system for monitoring and controlling the temperature. This improved the efficiency of the process and reduced costs.

Interviewer: Can you tell us about a time where you had to troubleshoot a complex process issue?

Candidate: We had an issue with one of our processes where the product was contaminated. I worked with the team to conduct a detailed analysis and eventually found that the root cause was due to a clogged pipe. We replaced the pipe and implemented a more regular maintenance schedule to prevent it from happening again.

Interviewer: Can you describe your experience with equipment selection and optimization?

Candidate: In my previous role, I was involved in selecting equipment for several different projects. I have experience with conducting feasibility studies and detailed design calculations to ensure that the equipment is suitable for the specific process requirements. I also have experience with optimizing equipment performance to improve efficiency and reduce costs.

Interviewer: Can you tell us about a time where you had to overcome technical limitations to achieve a project goal?

Candidate: In one of my previous roles, we were developing a new process that required a specific reactor that wasn’t available on the market. I worked with a team of engineers to design and build a custom reactor that met the specific requirements of the project.

Interviewer: Can you describe your experience with process automation?

Candidate: In my previous roles, I have experience with implementing and optimizing process automation systems. I have worked with a range of different systems, including PLCs, HMIs, and SCADA systems.

Interviewer: Can you tell us about a time where you had to work with a cross-functional team to achieve a project goal?

Candidate: In my previous role, I was part of a cross-functional team that was tasked with developing a new chemical process. We worked together to identify the requirements for the new process, design the necessary equipment, and conduct trials to optimize the process.

Interviewer: Can you describe your experience with safety management in a chemical manufacturing environment?

Candidate: Safety is a top priority in any chemical manufacturing environment. In my previous roles, I’ve had experience with developing safety processes and procedures, conducting safety audits, and implementing safety improvement projects.

Interviewer: Can you tell us about a time where you had to deal with a safety issue in a manufacturing environment?

Candidate: We had an incident where an employee accidentally spilled a dangerous chemical. I worked with the safety team to immediately evacuate the area and ensure that the employee received medical attention. We also conducted a thorough investigation to determine the root cause and implemented several new safety measures to prevent it from happening again.

Interviewer: Can you describe your experience with environmental compliance in a chemical manufacturing environment?

Candidate: Compliance with environmental regulations is critical in any chemical manufacturing environment. In my previous roles, I’ve had experience with developing and implementing environmental compliance programs, conducting audits, and identifying areas for improvement.

Interviewer: Can you tell us about a time where you had to implement a new environmental regulation in a chemical manufacturing environment?

Candidate: In my previous role, we had to implement a new regulation related to wastewater treatment. I worked with the team to identify the best treatment options and implemented a new system that met the new regulatory requirements.

Interviewer: Can you describe your experience with quality control in a chemical manufacturing environment?

Candidate: Quality control is essential in any chemical manufacturing environment. In my previous roles, I have experience with developing and implementing quality control processes and procedures, conducting quality audits, and identifying areas for improvement.

Interviewer: Can you tell us about a time where you had to identify and solve a quality control issue in a manufacturing environment?

Candidate: We had an issue where one of our batches did not meet the required specifications. I worked with the team to identify the root cause and implemented several measures to prevent it from happening again, including enhancing the quality control process, conducting more thorough testing, and increasing monitoring during production.

Interviewer: Can you describe your experience with project management in a chemical engineering environment?

Candidate: In my previous roles, I have experience with managing projects from conception to completion. I’ve led project teams, developed project schedules, and ensured that projects were completed on time and on budget.

Interviewer: Can you tell us about a specific project that you led, and what your role was?

Candidate: I led a project in my previous role where we were tasked with developing a new process for a specialty chemical. My role included overseeing the project team, conducting feasibility studies, and designing the necessary equipment. I was also responsible for managing the budget and ensuring that the project was completed on schedule.

Scenario Questions

1. Scenario: As a Chemical Engineer, you have been assigned to optimize the production process of a fertilizer plant. The current process uses 5000 kg of raw materials to produce 3000 kg of fertilizer. What is the yield percentage of the process? Provide your calculations and assumptions.

Candidate Answer: To calculate the yield percentage, we need to first determine the actual yield produced in the process, which is 3000 kg. Assuming an ideal theoretical yield of 5000 kg, we can now calculate the yield percentage using the formula: (actual yield/ theoretical yield) * 100.
Yield percentage = (3000/5000) * 100 = 60%

2. Scenario: You have recently joined a pharmaceutical company as a Chemical Engineer. The company is producing a medication that requires a pH of 7.2 for stability. However, you have noticed that the pH level has been fluctuating between 7.1-7.3, affecting the shelf life of the medication. What steps would you take to address this issue?

Candidate Answer: Firstly, I would investigate the root cause of the pH fluctuations by analyzing the raw materials, process parameters, and equipment used in the production process. Once the underlying cause has been identified, I would work to implement appropriate process control measures such as adjusting parameters, modifying equipment, or changing raw materials to ensure that the pH level is maintained consistently at 7.2. I would also validate the changes made to ensure that they are effective in reducing the pH variability.

3. Scenario: A client has requested a quote for producing a specialty chemical using a particular reaction pathway. The client has provided you with a reaction equation and a target yield of 90%. How would you go about creating a cost-effective and efficient production process?

Candidate Answer: To create a cost-effective and efficient production process, I would begin by conducting an initial feasibility analysis of the reaction pathway provided by the client. This would involve calculating the required quantities and costs of raw materials, energy usage, labor, and any other variables that may impact the production process. Based on these findings, I would propose an optimized process that takes into account the target yield as well as minimizing expenses without compromising on quality. I would also perform a process simulation to determine the efficiency of the proposed process in achieving the target yield.

4. Scenario: Your company is developing a new wastewater treatment plant, and you have been tasked with designing the chemical treatment process. The wastewater has an initial COD of 5000 mg/L, and the desired COD level for discharge into the environment is 200 mg/L. What is the required mass of the chemical agent (in kg/m3) that needs to be added to achieve this target? Show your calculations and assumptions.

Candidate Answer: To calculate the mass of the chemical agent required, we need to first determine the COD reduction target by subtracting the desired COD level from the initial COD level.
COD reduction target = 5000 - 200 = 4800 mg/L
Assuming that the chemical agent will completely oxidize the organic matter in the wastewater, we can now calculate the mass required using the formula:
Mass of chemical agent required = (COD reduction target * V) / (1000 * efficiency)
Assuming an efficiency of 90% and a total volume of 100 m3, we can calculate the mass of chemical agent required as follows:
Mass of chemical agent required = (4800 * 100) / (1000 * 0.9) = 533.33 kg/m3
Therefore, 533.33 kg/m3 of the chemical agent needs to be added to achieve the desired COD reduction target.

5. Scenario: You have been hired as a Chemical Engineer for a company that produces polyethylene using a high-pressure process. The company's current production capacity is 100 metric tons per day. The management has asked you to assess the feasibility of increasing the production capacity to 120 metric tons per day. What factors would you consider in your analysis?

Candidate Answer: Increasing the production capacity of a high-pressure polyethylene production process requires careful consideration of various factors, such as the available equipment, raw materials, energy required, capital investment required, and the impact on product quality.
1. Available equipment: The existing equipment would need to be assessed to determine if it can handle the increased production rate.
2. Raw materials: The availability, quality, and cost of the raw materials required would need to be assessed to ensure that the proposed increase in production is sustainable.
3. Energy requirements: The energy required for the increased production must be determined to ensure that the process remains energy-efficient and cost-effective.
4. Capital investment: The required capital investment to expand the production capacity must be evaluated to determine the financial feasibility of the proposed increase.
5. Product quality: The impact of the increased production capacity on the product quality must be assessed to ensure that the product meets the required standards.