Dehumidification System

[Bashir01219]

Dear Sir,
At present we are using a AHU with dehumidification from CARYAIRE capacity 9000 CFM.
The present system contain Desiccant Rotor with two electrical coil of 24 KW each, and our aim is to replace the electrical heating coil with a steam heating coil.
My question is what is the best and simple way to do it, if we want to do it with our own (including controlling system), and what are the critical points if we want to do it with the help of third party?
Our expected Humidity range is (RH) 30-60%.

[charlie n]

This should be reasonably easy. However, you first need to be sure of the temperature requirements of the reactivation process. Some are quite high and would require high pressure steam. Others will reactivate quite well using hot water at 90 degrees. Best first step would be to talk to the manufacturer.

[ref717]

Why do you want to use steam for the reactivation air instead of the simple electrical coil?. The process and properties of steam is complicated. To get the required temperature and mass flowrate you have to control the outlet pressure and study the steam saturation properties before it becomes steam condensate. You also need a steam generating unit, and think about its fuel and maintenance costs.

[Bashir01219]

Thanks, now i need clarification.......
Actually its a pharma industry and we have a prity good gas fired boiler, and we also provide a steam line for the AHU unit, we just need to install a system.
48 kw 12 hrs and 25 days in a month, electric bill is quite high. In Bangladesh power is not available, and we need to pay a fixed amount for gas, we r paying the gas bill but utilization is low, so to optimize the situation we r looking for steam coil dehumidification!

[ref717]

Now i got your point. Redesigning into steam coil heating is a good alternative heat source due to the present conditions you've mentioned. As chalie_n said, you must first consult the "OEM" of the dessicant rotor and discuss your ideas as well as ask the critical points to look for (e.g. desiccant air correct temp.,etc.). As for the steam piping, I'm sure you already have ideas because you have your own steam system. The usual piping accesories like isolating valves, PRV, relief valve, steam trap, solenoid valve, gauges, etc. should be included.

[sedgy]

hi bashir, just a point of interest , is the system full recycle , or how much fresh air intake have you got?

[Bashir01219]

We take near about 10 to 20 % fresh air in the cycle, and obviously we exhaust some portion of the return air.