Orientation (Part - 1) | Chemical Technology - Chemical Engineering PDF Download

Orientation

1.1 Why a chemical engineer needs expertise in process technology ?

A process engineer at operation in chemical plant shall have a deeper understanding of the technology on which the process plant is built to produce the profit making chemicals. A chemical engineer with sound knowledge in process technology has the following distinct advantages:

a) Ability to clearly distinguish the functional role and importance of various processes and operations in the process plan

b) Technical knowledge with respect to the selection of important parameters such as Temperature, Pressure and underlying physical principles of a process.

c) Ability to distinguish various process streams and their conditions of operation (Temperature, pressure and phases)

d) Basic knowledge for process troubleshooting and necessary safety precautions associated to a process/operation.

1.2 How to master fundamentals of process technology? 

To master chemical process technology five crucial steps are involved namely:

a) Raw-Materials and reactions: A chosen process route to manufacture desired chemicals with appropriate purities will eventually lead to preparing a list of raw-materials and utilities. Thereby, prominent reactions can be also known

b) Conceptual process flow-sheet: A conceptual process flow-sheet where a chemical engineer has an abstract representation of the actual process flow-sheet will enable quicker learning. A conceptual process flow-sheet typically constitute the following attributes:

• Raw-material purification (Solid-fluid operations such as cyclone separators, ...bag filters etc.)
• Raw-material processing (Heat exchange operations such as furnace ...heating, cooling etc.)
• Raw-material to product transformation (Reaction operations using CSTR, ...PFR, PBR and Batch reactors)
• Product purification (In separation processes such as flash, distillation, ...absorption and extraction)
• Product processing (heat exchangers, phase change units)
• Recycle of un-reacted raw-materials as recycle streams to the reaction ...operations.
• Technological know-how of each unit operation/process to eventually identify its functional role in the process flow-sheet
• Temperature, pressure and composition of streams entering the unit ...process/operation
• Temperature, pressure and composition of streams leaving the unit ...process/operation
• Phases of various streams entering and leaving the unit process/operation
• Associated waste and environmental hazardous products generation

c) Process intensification in the form of heat-integration, stream utilization and waste reduction and multiple recycle streams: These options are in fact optional and they enrich the energy enhancement and waste reduction efficiency of a process plant. Originally, chemical plants developed without such process intensification policies have been subjected to rigorous research and case study investigations to identify opportunities for cost reduction and better energy/waste management.

d) Additional critical issues related to various unit operations/processes

• Cost reduction approaches/process economics: How the operating variables (such as temperature, pressure, flow-rates, reflux rates, heating rate etc.) affect the cost of the unit operation/process
• Safety issues: What safety issues are most relevant and need frequent ...monitoring

e) Alternate technologies: For a desired function of a process unit, can thereby alternate technologies that could reduce the cost and even then provide the same functional role and desired flow rates and compositions of the emanating streams.

1.3 How much to memorize for a chosen technology ?

To a large extent, University education expects a chemical engineering undergraduate student to remember and draw at least a conceptual flow-sheet. However, when a systematic approach is not adopted in the learning process, it is rather difficult to remember all flow-sheets and relate to the logic behind their role in the process topology. Therefore, a well-trained student in process technology remembers process flow-sheets with logical sequence of unit processes/operations and not by strict memory.
 

1.4 Advantages of suggested learning approach for mastering process technology 
a) Trains student to be more analytical/concept-oriented rather than with memorized knowledge that is bereft of logical reasoning

b) Systematic approach enables the growth of students’ interest in the subject.

c) Additional concepts further reveal to the student how to gradually complicate process technologies for maximum efficiency.

d) Inculcate strong interest in the student towards technology research and innovation by enabling a learning environment that fundamentally targets the technological know-how.
 

1.5 Prominent unit-operations and unit-processes in chemical industry 

A detailed summary of various prominent unit operations/processes and their functional role in the chemical plant are summarized in Table 0.1 along with suitable figures.

Table 0.1: Important unit operations/unit processes and their functional role in chemical process technology.

A pictorial representation of various unit processes and operations that are often encountered in chemical process flowsheets is presented in Table 0.2. Along with these figures, their function role in the process technology is also presented.