Current production facility is giving away a diluted aqueous ammonia solution which is a by-product from one of their chemical reactors.
engineering
Description
Problem Statement
Current production facility is giving away a diluted aqueous ammonia solution which is a by-product from one of their chemical reactors. However, another reactor in their facility, which operates in batch mode, requires ammonia with a minimum concentration of 87 mol% NH3 in water. Instead of giving away the aqueous ammonia and then re-purchasing pure ammonia, the plant proposes:
to install a 30,000 US gallon intermediate storage tank for the diluted aqueous ammonia solution,
to install a continuous distillation system with bubble cap trays to recover the ammonia from a 1.5 to 25 mol% NH3 in water solution (i.e., “diluted aqueous ammonia stream”), and
to install a 25 m3 concentrated aqueous ammonia product storage tank (indicate the desired orientation of the tank, i.e., vertical vs. horizontal installation).
Diluted aqueous ammonia conditions entering the feed pump:
Concentration: 1.5 to 25 mol% NH3 in water
Temperature: 40 to 75F
Pressure: the pressure gauge is broken, but the operator mentioned that the diluted aqueous
ammonia entering the pump is in a liquid state.
Mass flow rate: 1600 kg/h
The environmental engineer emphasized that the water treatment facility cannot accept any effluent from the new process that contains more ‘than a few ppm of NH3 in water’.
Additional Information
Utilities:
Cooling tower water supply: 25C; max. 800 USGPM
Glycol supply: 20 vol% mono-ethylene-glycol in water; 45F; available in a very limited quantity.
Heating medium: Dowtherm G; 570F, max. 12,000 USGPH
Plant air: max. 150 psig
Instrument air: max. 150 psig
1. Draw a P&ID of the system, i.e., the P&ID can be neatly drawn by hand.
o You may wish to exclude the following from the P&ID: the waste water treatment facility, the diluted aqueous ammonia storage tank, and the heat tracing of pipes and equipment.
2. Determine:
o the heating medium flow rate to the reboiler,
o the cooling medium flow rate to the condenser, and
o the reflux pump type, model number, and manufacturer.
Indicate all instruments (e.g. flow, pressure, temperature) on the P&ID.
Show all valves and pressure relief devices.
Perform Hazard and Operability (HAZOP) analysis.
