Preparation of Technical Interviews

Welcome to the new chapter of the blog! From this week, I will start writing about the answers of some technical engineering questions with examples. These questions are taken from some websites, all sources are indicated in References section. Happy reading and learning!

Q1: Chemical engineers often need to work with both unit operations and unit processes. Can you tell me, in your own words, the difference between them?

A: This question deals with the differences between two basic aspects of chemical engineering. Most chemical engineers with any training or knowledge of the subject should be able to give you some idea of this contrast in their own words. The answer deals with mass, concentration, energy and reactions. You can use this question to test the potential hire's introductory knowledge on the subject. What to look for in an answer:

Specific knowledge of how the principles work
Ability to explain the processes clearly and concisely
Concrete examples of the items

Example, “Unit operation involves changes that occur such as evaporation or distillation. Unit process involves chemical reactions such as oxidization or reduction of a compound."

Extended answer:

Unit operation-

In chemical engineering and related fields, a unit operation is a basic step in a process. Unit operations involve a physical change or chemical transformation such as separation, crystallization, evaporation, filtration, polymerization, isomerization, and other reactions. For example, in milk processing, homogenization, pasteurization, and packaging are each unit operations which are connected to create the overall process. A process may require many unit operations to obtain the desired product from the starting materials, or feedstocks.

For more info, check out this video:

Unit processes-

A ''unit process'' is one or more grouped operations in a manufacturing system that can be defined and separated from others.

In the diagram below, the summary of the main points is given:

Let's go further and the second question:

Q2: As a chemical engineer, you have some knowledge of the basic components of raw materials. Can you tell me about the material requirement planning process?

Chemical engineers often work with raw materials in various ways. They use chemical reactions to separate, combine or alter these materials and how they behave. Your candidate should be able to use material requirement planning to determine how much of a basic material is needed for production. The individual should also be comfortable using special computerized tools to help them gauge these amounts accurately and reduce waste. What to look for in an answer:

Understanding of material requirement planning
Process used to ensure accurate planning for necessary materials
Strategies to correct errors that may happen

Example, "Material requirement planning allows me to take a look at the amount of a finished product the company wants and provide raw materials to meet that goal."

Extended answer:

Material requirements planning (MRP) is a system for calculating the materials and components needed to manufacture a product. It consists of three primary steps: taking inventory of the materials and components on hand, identifying which additional ones are needed and then scheduling their production or purchase. If we look at why MRP is important, because MRP is one of the most widely used systems for harnessing computer power to automate the manufacturing process.

Let's see 2 diagrams about this question,

Q3: Some of your responsibilities as a chemical engineer may relate to efficiencies. In your own words, can you explain the philosophy of "just in time?"

Companies want their chemical engineers to do their jobs while looking for ways to be more efficient and reduce unnecessary waste. Many chemical engineers use a particular philosophy as a way to gauge their own efficiencies and take steps to improve things when necessary. A good candidate should be able to describe this lean manufacturing process. What to look for in an answer:

Precise understanding of the "just in time" philosophy

Specific examples of applying it to lean manufacturing
Willingness to make changes

Example, "'Just in time' philosophy is all about managing both time and resources to increase the bottom line. I apply several lean manufacturing techniques regularly."

Extended answer:

Just-in-Time means producing quality products efficiently through the complete elimination of waste, inconsistencies, and unreasonable requirements on the production line. In order to deliver a vehicle ordered by a customer as quickly as possible, the vehicle is efficiently built within the shortest possible period of time by adhering to the following:

When a vehicle order is received, a production instruction must be issued to the beginning of the vehicle production line as soon as possible.
The assembly line must be stocked with the required number of all needed parts so that any type of ordered vehicle can be assembled.
The assembly line must replace the parts used by retrieving the same number of parts from the parts-producing process (the preceding process).
The preceding process must be stocked with small numbers of all types of parts and produce only the numbers of parts that were retrieved by an operator from the next process.

Additionally,

Just-in-time (JIT) manufacturing is frequently described as a process for achieving continuous improvement through the systematic elimination of waste and variations. It encompasses not only the production control techniques but also total quality control programs, facility and line design, employee training and involvement attitude, etc., This picture below illustrates how the JIT system is related to other production management concepts.

Q4: Different industries use different types of equipment, but there are some basics you know from your training. Can you describe some common chemical engineering equipment?

Even a basic chemical engineer should have some knowledge of the most ubiquitous types of equipment used in their field. This question can help you test the general knowledge of your potential hire and see if they're ready for any entry-level positions. Specific types of equipment can vary across specializations, but many of them share some basic things in common. What to look for in an answer:

Knowledge of chemical engineering equipment
Understanding of how and when to use each piece
Familiarity with the latest industry trends

Example, "I use various separators in my job to keep individual chemicals from reacting to one another and absorbers to analyze different chemical gases."

Extended answer:

Process equipment is used in several applications like water treatment, steam power generation, pipelines, salt water disposal etc., where chemical or mechanical methods are applied. Some examples of process equipment popularly used in these industries are pumps, valves, vessels, filters, coolers, heat exchangers, pulsation dampeners and piping. Each of this equipment is very important because of their indispensable usage in the working of a process.

References📖

🔥Now, time to say goodbye👋🏻 until new post of this chapter 🧬 and Stay tuned for more content 😉🌝✨!

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Preparation of Technical Interviews

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