Write a 2 page essay describing how business decision support systems have evolved over the past several decades as computer and data capabilities have grown. The rubric for this assignment can be viewed when clicking on the assignment link.

Evaporators

Understand the process of evaporation and why evaporators are used Understand hazards of evaporator systems

“To lose or cause to lose liquid by vaporization, leaving a more concentrated residue”

 Reduce volumes for storage (HA evaporation) ◦ Reprocessing raffinate volumes are reduced by about 50 -100 times

reducing the storage volume required

 Product concentration ◦ Without evaporation, the downstream processes would become

inefficient

Simple and robust with no moving parts

and min maintenance

 Poker  Thermosyphon  Kettle

Feeding

Hot Vapour discharge Disentrainment

Recirculation of liquor

Heating

Steam

 Reduces boiling temperature and therefore reduces corrosion

 Improving temperature driving force  Keeps the size of the evaporator down  To avoid runaway reactions (Reaction rate)  Reduce volatile ruthenium

Evaporator Bump Over

Click Here to view video  Movie file (mpeg)

energetic event caused by a sudden conversion of superheat in a liquor to a vapour, which in turn carries liquor with it.

Cause: The Application of vacuum to a liquid, where the temperature of the liquid before the vacuum is applied (or increased) is greater than the boiling point of the liquid at that applied vacuum. The liquid becomes superheated relative to its boiling point at that reduced pressure.

• Loss of vacuum without loss of steam heating followed by re- instatement of vacuum

• Loss of vacuum with loss of steam (but not radiogenic heat) followed by re-instatement of vacuum

• Air in-bleed control valve fails shut

• Temporary loss of cooling water to the condenser without tripping the vacuum raising ejectors

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0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80 100 120

Temp C

B ar

a

Partial loss of vacuum

Continue heating

Vacuum reinstated

BUMP OVER !!

Do not apply a vacuum to a liquid where the temperature of the liquid before the vacuum is applied (or increased) is greater than the boiling point of the liquid at that applied vacuum

 Minimise loss of vacuum events  Trip the steam heating on loss of vacuum  Trip vacuum raising ejectors on loss of vacuum  Minimise hot/self heating solids build up (suspend/wash out)  Cool contents of evaporator to a temperature that is lower

than that before the loss of vacuum, then reinstate the vacuum

Loss of cooling capacity due to failed components This is only of concern if the evaporator contents are self heating The heat load of the evaporator contents will be limited to ensure sufficient cooling capacity is available

Loss of / or low cooling water flow to the evaporator condenser

This will result in loss of vacuum to the condenser and subsequent evaporator pressurisation It is normal to trip the steam heating and / or the vacuum raising ejectors on low cooling water flow to the condenser If cooling water is restored to the condenser without having tripped the steam heating, then bump / boil over may result

Activity Breakthrough  Due to failure of a heating / cooling component  Pressure cascade reversal. Due to steam collapse in the heating

component resulting in the pressure in the evaporator being greater than that in the heating component

 Protection is by Automatic Isolation System (AIS). On detection of activity in the steam condensate (or cooling water) returns an automatic isolation valve will close preventing radioactivity migration

Hydrogen Build-up from radiolysis

Solvent Nitrate Reactions Reaction of nitric acid with solvent at elevated temperature

reaction is self accelerating and can result in evaporator pressurisation due to high non-condensables

Avoided by ensuring solvent cannot be fed to an evaporator that contains nitric acid

Low density trip in feed tank, controls on upstream plants (steam distillation) and limits on evaporator temperature

 Ammonium Nitrate decomposition

• Thermal decomposition giving non condensables. This can also result in evaporator pressurisation

• Limit Ammonium Nitrate concentrations and evaporator temperature

 Evaporator pressurisation must be avoided since it can force active liquor out of the controlled area.