Week 2+4 Flashcards
What are the PID limitations?
Doesn’t show how straight the process lines are.
The proximity of items isn’t clear.
The actual size of equipment.
What is the function of steam trap?
separates condensate from steam.
What are the abreviations for:
Valves / Relief Valve / Bursting disc / Control valve / Sample point
V / RV / BD / CV / SP
What are the two main types of control loops?
Feedback - control system measures changes in a process output and then adjusts variable to return output at desired setpoint.
Feed Forward - Control system measures disturbance and adjusts variable to compensate for it so that controlles output is not affected.
Describe what ratio control and cascade control are.
Ratio - One stream is controlled in ratio to another control stream.
Cascade control - Primary controller is used to adjust the set point of a second controller.
what is the function of a HAZID
Identifies hazards / Finds interactions between parts of the plants and surroundings which could cause a major accident.
What is the function of a HAZOP
Identifies hazards and operability problems.
Provides action and solutions to deal with them.
what is the function of a HAZAN?
Calculates how likely a hazard is of occuring.
Quantifies with probability.
What is the function of LOPA.
Defence systems against the disasters (checks the alarms/trips and whether they are sufficient enough).
What is the difference between upper flammability and lower flammability?
Upper - the concentration in air above which a flame cannot exist.
Lower - the concentration in air below which a flame cannot exist.
What are the following points in terms of flammability:
Flash point
Autoignition temperature
Minimum oxygen concentration
Flash point - Liquid temperature above which vapour produces ignitable mixture in air.
Augnition temperature - enviromnent temperature above which energy from enviromnent provides ignition.
MOC - Oxygen concentration below which combustion is not possible.
What information is required to plot the flammability diagram.
Lower flammability limit
Upper flammability limit
Stoichiometric composition
Minimum oxidant for combustion
what is the difference between a flashfire and a poolfire?
Flashfire: Occurs when a vapour cloud burns.
Main hazard is contact with flame.
Pool fire: Starts with the release of flammable material.
what are some fire responses?
have multiple layers of protection.
Management of source ignition.
Response plan.
what is a BLEVE?
Boiling liquid expanding vapour explosion.
Short duration.
