Wattage Required to Heat Acid

Hmmmmm..................

• How well insulated is the tank?
• How full is the tank?
• What steps are to be taken to stop the liquids evaporating from the top of the tank and the thermal loss resulting?
• What is the proportion of phosphoric acid/sulphuric acid/water in the tank contents mix?

For guidance, 1400kg of water to be raised by 25Cdeg in 1 hour would take 4.18kj/kg.degC x 1400kg x 25degC / 3600sec ≈ 41kW ignoring losses. The heater is going to need to be rated higher than this. While the tank could be made of any number of plastics the heater needs to be made of exotic materials in order to withstand the agressive nature of the fluids and the elevated temperatures.

So far, there is no guidance as to the agitation in the tank. Without agitation, the contents will stratify, leaving a cool zone below the heater and the contents above it running possibly hotter than setpoint.

• Where is the take-off connection from the tank - above the heater or below it?
• What controls are in place to turn the heater off were the tank level to drop below the point where the heater element is exposed to air?
• Does the heating have to take place in a tank, or could it take place somewhere else, like in a graphite heat exchanger using available hot utility fluids, the process becoming continuous rather than batch?
• What fume extraction and scrubbing is in place?
• What temperature controls are in place to switch the heater off once the desired temperature has been reached?
• Is there scope to use heat-of-dilution of the acids to provide part of the heating load?

thanks for the valuable feedback.

Regards

Rakesh

You might find these two links helpful as they give information on how to calculate heat losses from tanks and heating requirements. You will need some properties of the mixture, or at least estimate them i.e. Density and Specific Heat.

The Spirax-Sarco link gives you how to calculate heat losses and using steam heating (this is an excellent site for tutorials on steam use). The watlow link should give you an idea on electrical heating requirements

http://www.watlow.com/reference/refdata/0303.cfm

http://www.spiraxsarco.com/resources/steam-engineering-tutorials/steam-engineering-principles-and-heat-transfer/energy-consumption-of-tanks-and-vats.asp