Friday, May 2, 2008

Safety of Dryer operation (a chemical engineering application)

Safety aspects are given priority is chemical engineering design, since it is a legal and moral obligation to safeguard the health and welfare of its employees and the general public. Safety is also good design practice needed to ensure safe operation will also ensure efficient operation.

Safety in process design can be considered under the following precautions.

· Identification and assessment of the hazards

· Control of the hazards

· Control of the process

· Limitation of the loss

Identification and assessment of the hazards

All manufacturing processes are to some extent hazardous, but in chemical processes there are additional, special, hazards associated with the chemicals used and the process conditions. The drying process of Cassava starch and poly lactic acid does not posses any chemical hazard but it is having risks with process condition.

Operators, supervisors, maintenance crew and labours can face following safety hazardous while operating, inspecting, maintaining and cleaning.

· Contact with hot surface [Most case operators, supervisors and labours]

· Exposure to steam leaks [Most case operators, maintenance crew and labours]

· Electrical shocks [Most case operators and maintenance crew]

· Hack by moving parts such as drum, belts, and wheels [Most case operators, maintenance crew and labours]

Control of the hazards and the process

Implementing proper safety control systems against above safety hazardous will reduce the near miss causes, injuries and fatalities. The hot surfaces cannot be avoided in dryers. However hot surfaces can be isolated with fences, heat insulations, heat guards, covers … etc. Steam pipes should be insulated mainly to avoid heat losses and on the other hand, it will eliminate hot surfaces. Glass wool layer and aluminum foil is ideal for insulating steam pipes.

Proper maintaining and inspection of steam valve, joints, previous vulnerable points in steam distribution system will avoid sudden steam leaks, one of deadliest risk in dryer operation.

Electrical shocks can be eliminated through proper wiring, standard insulation and installing circuit break switches.

Moving parts cannot be eliminated from any operation; however, risk of hacking with moving objects can be eliminated through isolated with fences, guards, covers

Limitation of the loss

Control of the hazards and the process will reduce risk up to some extent. However in order to limit losses due to accidents advanced safety measures must be taken. Operators, supervisors, maintenance crew and labours must be equipped with required occupational safety equipments such as gloves, goggles, shoes …etc. Following list will brief the required equipments for connected operation activities.


Connected operation activity

Safety equipment



Eye Goggles



Eye Goggles, Gloves, Shoes

Maintenance crew

Repairing and trouble shooting

Gloves, Shoes, insulated tools, Eye Goggles



Eye Goggles, Dust masks

Purpose of each safety Equipment

Safety equipment


Eye Goggles

Protect eyes from steam splashes, dust particles, metal scraps, …etc


Project hands against hot surfaces, sharp edges


Project foots from damages, Protect from electrical shocks

insulated tools

Protect from electrical shocks

Dust masks

Protect respiratory system from poor ambient air quality

Providing safety equipments and taking safety controls is not sufficient. Increasing awareness on safety practices among employees will ensure a better working environment with minimum accidents. Occupational safety seminars, presentations, discussions, notices, posters, banners are some of better mediums to increase awareness among employees.

EHS coordinator of the plant should inspect installed safety measures, awareness and usability of safety equipments, near misses and accident rates of the process and must take proper measures to eliminate weakness in occupational safety environment.

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