STORAGE OF SOLVENTS/GASES

Storage of Solvent• Common Solvents:– Acetone, Acrylamide, Benzene, Methanol, Toluene, etc.

• Solvent Properties:– High volatility at ambient temperature– Inflammable – Toxic

Difficulties faced

• Loss of solvent due to:– Breathing losses:Vapor pressure variation with temperature– Filling losses:Discharging and Refilling losses– Boiling losses:Vapor pressure higher than atmospheric pressure

Types of Tanks

• Standard Fixed-Roof Storage Tank• Variable Volume Tanks

– Vapor Lift Roof Type– Internal Floating Roof Type– External Floating Roof Type(a)Pan(b)Pontoon(c)Double-Deck

Accessories

• Seal• Drains• Pipe Supports• Vents• Manholes• Rolling Ladder• Anti-Rotation Device• Gauge Platform

Floating Roof Type

Vapor Lift Type

Example: Methanol Storage

• Type of storage tank: Floating roof tank• Safety accessories:

– Provision for fire-fighting– Provision for raw water sprays incase of increased

temperatures– Pressure and temperature indicators– Biofilter and scrubber assembly to avoid

environmental pollution due to filling losses.

Standards for VOCsCapacity (litres) Vapor Pressure (mm Hg) Type

> 151,400 78-570 Floating roof

>151,400 >570 Floating roof with vapor recovery system

>946.25 >78 Permanent submerged fill pipe

Source: KRS Chapter 77 Air Pollution Control

STORAGE OF GASES

• Currently more than 200 substances shipped in compressed cylinders

• Two major groups: liquefied & non-liquefied • Compressed gases lumped into families

– Atmospheric Gases– Fuel Gases– Refrigerant Gases– Poisonous Gases

Hazards associated with gases in cylinders

• Fire / Explosion from the release of flammable gases near ignition sources

• Spontaneous combustion from oxidizing gases• Exposure to toxic or corrosive gases• Asphyxiation

• Gases stored under 100’s of atmospheres of pressure

Pressure Related Hazards

• Valve damage – leakage of gas• Cryogenic/Liquefied Gases-Frostbite on

release• Heating/Impact – Explosion/Shrapnel• Denser than air gases – tend to collect• Rapid release & Expansion – Cold Hazard• Large gas cylinders – severe strain from

inappropriate handling

Gas storage vessels

• Low Pressure Storage Tanks (LPST)• Static Mobile Pressure Vessels (SMPV)• Spherical Storage vessels• Horton spheres

LARGE SCALE AMMONIASTORAGE AND HANDLING

• Why are these facilities needed?• Why is refrigeration needed?• What are the major components?• How is ammonia transported to and from the

facilities?

Major Components

• Low Pressure Storage Tank• Compressor• Flash Tank / Intercooler• Condenser • Receiver

Refrigeration in an AmmoniaStorage Facility

• Superheated vapor passes from storage tank to 1st stage of compression

• Hot vapor from 1st stage cooled in flash tank preparation for 2nd stage

• Vapor at saturation temperature passes to 2nd stage compression

• Hot vapor passes to the condenser: Heat rejected to environment

• Condensed ammonia gravity drains into the receiver

Refrigeration (contd.)

• Receiver level control sends liquid to flash tank

• Flash tank level control sends liquid, at intermediate pressure, to the storage tank

• Flare for burning ammonia vapor during refrigeration system interruption

• Knockout pot protect the compressors from damaging liquid entry are also utilized

Case Study: Boston Molasses Disaster• Great Molasses Flood / Great Boston

Molasses Tragedy• January 15, 1919: Neighborhood of Boston,

Massachusetts• Bursting of Molasses Tank• 21 Killed, 150 Injured

Aftermath of the Disaster

• Huge Molasses Tank Collapsed• 15 m tall; 27 m dia.• Unleashed an immense wave of molasses• Moving at 56 km/hr and 200 kPa• Causes: Poor Construction & Improper Testing• Rise in air temperature• Fermentation: Production of Carbon di Oxide

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