What is meant by process equipment design?

A number of types of equipment such as reactors, evaporators, crystallizers, distillation columns, absorbers, and heat exchangers are important in various chemical process plants. For any process like physical, chemical, mechanical, or thermal treatment of raw material or product, arrangement of various mechanical equipment is required. To set up a process plant, it is imperative to carry out the design of these pieces of equipment on priory. Therefore, it is one of the basic steps in a chemical process. In the context of chemical engineering, the process equipment design is the selection and order of units for a particular physical and chemical alteration of the itinerary. It is a central part of chemical engineering and may be considered to be one of the fundamental topics of the chemical industry, accumulating the elements altogether.

Process Engineering and Design

Process engineering is the practical understanding and implementation of the important principles and laws of nature that permit people to alter raw materials and energy into items that are utilized by society at the industrial position. Taking the benefits of the driving forces of nature like pressure, concentration slopes, and temperature, the law of conservation of mass, and engineers responsible for processes could generate the methodology to integrate and purify quantities of the chemical products. Process design is the new facilities design or it could be the transformation or expansion of current facilities. The design begins at a conceptual level and ultimately terminates in the form of fabrication and construction drafted plans. Process equipment design is closely related to the unit operation design and that too in large quantities. 

Process engineering is accountable for the development of design, operation, control, optimization, and escalation of chemical, physical, and biological processes. Process engineering encompasses a variety of industries, like agriculture, automotive, biotechnical, chemical, food, development, mining, material, petrochemical, nuclear, pharmaceutical, and software. The application of computer-based methods to process engineering is known as process system engineering. Another example is the International Space Station which is one of the marvels and it is a multinational collaborative project taking into account five participating space agencies, namely, NASA (National Aeronautics and Space Administration, United States), Roscosmos (Russian Federal Space Agency, Russia), JAXA (Japan Aerospace Exploration Agency ,Japan), ESA (European Space Agency ,Europe), and CSA (Canada Space Agency, Canada).

Stages of Process Equipment Design

Process Engineering design consists of the stages in which engineers make processes or projects. Usually, the design phase is iterative, processes are restarted or reworked to function properly. The five stages of process engineering design:

  1. Conceptual: the first phase in design in which a solid foundation is built.  This stage encompasses a description of the proposed project.  Illustrative drafts and models are produced during this particular phase.
  2. Front End Engineering Design (FEED): this stage focuses on the technical requirements of the design, as well as a rough investment cost. Several times, the FEED phase will reflect almost all of the specific requirements of the client.
  3. Detailed: this phase provides the full definition of every aspect of the project’s development. It contains various studies to be performed before the beginning of the actual project construction. This is the stage where plans, specifications, and estimates are created and finalized.
  4. Construction: the physical implementation of the project.
  5. Commissioning: the final phase in engineering design. Operations of the systems and equipment are initiated and the project is lead to actual and full functionality.

Documentation of Process Design Equipment

Process design documents define the design and they make sure that the design elements are suitable together. They are useful in communicating ideas and plans to various engineers involved with the design, external regulatory agencies, equipment vendors, and construction contractors.

Process design documents include:

  • Block flow diagrams (BFD): Easy diagrams comprising rectangles and lines indicating major material or energy flows.
  • Process Flow Diagrams (PFD): Particularly, more complicated drafts of crucial unit operations, as well as flow lines, are made. They generally consist of a material balance, and seldom an energy balance, showing typical or design flowrates, stream compositions, as well as stream and equipment temperatures and pressures.
  • Piping & Instrumentation Diagrams (P&ID): Figures depicting every pipeline with its class (carbon or stainless steel) and the pipe size (in diameter). They also show valving along with instrument locations and process control schemes.
  • Specifications: Written design commands of all main equipment materials.

Process designers typically note operating manuals on the procedure to start up, operate, and terminate the process. They usually also generate accident plans and projections of process operation on the environmental surroundings. Documents are maintained after the construction of the processing facility for the operating personnel to refer to. The documents also are utilized when any specific changes to the facility are decided prior. Process flow sheeting is a primary method of developing the process documents.

Design Considerations

Many considerations need to be made when designing any chemical process unit. Design conceptualization and considerations shall start when the procurement of product purities, yields, and throughput rates are defined altogether.

Objectives include that a design may strive for are throughout rate, process yield and product purity.

Constraints are inclusive of capital cost (the amount of budget or investment to construct end to end process), available space (the area of the land to build the plant), safety purposes (consideration towards risk analysis of industrial accidents or hazardous chemicals), environmental impact on emissions and effluents, waste production/recycling (manage waste produced as a side product of the process for not to harm the surroundings), operating and maintenance costs (represent the variable cost of the operation of the plant). Other factors are flexibility, reliability, and redundancy.

Process engineering concerns the necessity of several tools and methods. Depending on the exact nature of the system, processes need to be simulated and modeled using mathematics and computer science. Processes, where phase change and phase equilibria are applicable, need analysis using the principles and laws of thermodynamics to estimate modifications in energy and efficiency is desirable. In contrast, processes that focus on the flow of material and energy as they approach equilibria are best analyzed using the disciplines of fluid mechanics and transport phenomena. Disciplines within the department of mechanics are required to be applied in the presence of fluids or porous and dispersed media. Materials engineering principles also are required to be practiced, wherever relevant.

Context and Applications

Process equipment design is a major field of chemical engineering. It is considered to be the forum of that field that brings together components of all fields. This topic is studied by the students who undergo Bachelors of Technology (Chemical Engineering), Masters in Science (Process Equipment Designing), and Masters in Science (Chemistry).

Practice Problems

Q1. What is the full form of FEED?

  1. Front End Engineering Design
  2. Front Early Engineering Design
  3. Front End Engineering Draft
  4. Fire End Engineering Design

Correct Option: a

Explanation: The full form of FEED is Front End Engineering Design and this stage focuses on the technical requirements of the design, as well as a rough investment cost.

Q2. Identify the correct order of stages in process equipment design.

  1. Conceptual, Detailed, FEED, Construction, Commissioning
  2. Construction, FEED, Detailed, Conceptual, Commissioning
  3. Conceptual, FEED, Detailed, Construction, Commissioning
  4. Conceptual, FEED, Detailed, Commissioning, Construction

Correct Option: c

Explanation: The correct order of stages in process equipment design is Conceptual, FEED, Detailed, Construction, and Commissioning.

Q3. How many stages are there in process equipment design?

  1. 2
  2. 3
  3. 4
  4. 5

Correct Option: d

Explanation: There are 5 stages in process equipment design, namely, Conceptual, Front End Engineering Design (FEED), Detailed, Construction and Commissioning.

Q4. What do design conditions mainly contain?

  1. Objectives and products
  2. Objectives and constraints
  3. All the above
  4. None of the above

Correct Option: b

Explanation: Design conditions mainly contain objectives which include that a design may strive for are throughout rate, process yield and product purity and constraints which are inclusive of capital cost.

Q5. What is the full form of P&ID?

  1. Piping and Instrumentation Diagrams 
  2. Piping and Information Diagrams 
  3. Piping and Instrumentation Draft
  4. Preparation and Instrumentation Diagrams 

Correct Option: a

Explanation: The full form of P&ID is Piping and Instrumentation Diagrams and they depict valving along with instrument locations and process control schemes.

  • Viscosity
  • Process design technology
  • Piping and instrumentation

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