Distillation Column Hazop

Transcript

Distillation column The studies on distillation column suggest the following objectives: 1. Product quality control to maintain either the overhead or bottom composition at a specified value 2. Material balances control to maintain its column hold-up and overhead and bottom inventories between maximum and minimum limits. 3. Constraints. The column should not flood. Pressure should be high enough to maintain effective column operation and the temperature difference in the reboiler should not exceeded critical temperature difference. HAZOP Studies on Distillation Column Guide word NO Deviation No flow      Possible causes Pipe blockage Control valve shut Valves fail Tube leakage and blocking Pump failure Consequences    Column dry out Possible dangerous concentration No operation     LESS Less Flow      MORE More flow    Pipe blockage Control valve shut Valves fail Tube leakage and blocking Pump failure   Control valve is fully opened Increase pumping capacity Control valves failure  Column dry out Changes in product quality        Flooding in the column Changes in product quality Temperature decrease Rise in bottom    Action required Install low level alarm Check maintenance procedure and schedule Make bypass Emergency plant shut down Install low level alarm Check maintenance procedure Make bypass Emergency plant shut down Install high level alarm Check maintenance procedure and schedule Install control liquid level  HIGH High pressure High Temperature          LOW Low pressure  Vapor pressure high Pressure indicator controller fail Instrumentation failure More steam flow Exchanger tube failure High steam pressure Cooling water in condenser failure. Reboiler control failure Heating medium leak into process Vapour line leakage            Low temperature      Instrumentation failure Less steam flow Loss of heating (steam leakage) Low steam pressure and temperature Ineffective isolation      Low efficiency of separation Rupture of column or other related equipment Product loss Separation cannot be done Changes in product quality Column flooding Film boiling in column and reboiler Phase effect Pressure changes Low efficiency of separation Loss of products Pressure change Product loss Changes in product quality Ineffective separating process Phase effect       valves Install flow indicator Make bypass Install high pressure alarm Install pressure relief valve Install temperature indicator controller Instruct operator on procedure Attention to heat input and output control  Install pressure indicator  Install temperature indicator Instruct operator on procedure Upgrade isolation Attention to heat input and out control   