Deaerator Sizing

Link above Spirax sarco
Pierre

What actually do you want to size?

for info

Hi Mr. Pierre,

I did go through Pressurized Deaerators material in Spirax Sarco, I however wanted more detailed information and was looking for some book or some chapters from book or some references which I can use to perform sizing calculations accurately.

I want to calculate the following as part of the Deaerator Sizing calculations:

1. Deaerator Storage tank sizing basis.
2. Stripping Steam flow rate calculation.
3. Feed Water flow rate calculation.

Calculations 2 and 3 will come from Heat Balance.

Thanks and Regards,
Pavan Kumar

Hi,
You may find pointers using this link.
Good luck
Pierre

Hi,
Pierre

So, Pavan .... You want to know how DEAERATOR VESSELS and internal assemblies are designed .... for your export market ?

Did I get that right ?

.... Is it correct that you are NOT trying to replace a single deaerator .... ?????

You are looking for an education from kind strangers ?

...... OK .... Come at me haters !!!

MJCronin
Sr. Process Engineer

Hi MJCronin,

I wanted learn about Deaerator sizing for my upcoming project.

Thanks and Regards,
Pavan Kumar

Specific sizing calculations and details like nozzle design, configuration etc. are critical and normally not shared by the Equipment Manufactrers. Process Engineers engaged in any operating plant or even involved in basic design, prepare purchase specification for vendor's supplied equipment which requires fundamental inputs like Process Flow Diagram, P&ID, Flow Rates and other operating conditions, preferred plot plan, based on space availability. This set of infomation is usually sufficient for any vendor to provide budgetary quotes for us to proceed with project cost estimation. I am not sure such curitical design information enabling you to design any equipment in-house is available in any textbook.

To answer your questions related to sizing,

1. Sizing of the Storage Tank though depends on a number of factors, many design practices at owner's facility or process design center suggest not less than 20 minutes of hold up between maximum overflow and minimum level alarm point after which the feedwater pump trips.

2. Steam flow requirements can be calculated as follows

Steam Flow Kg/h = Water Flow x (Enthalpy of Water at outlet - Enthalpy of Water at Deaerator Inlet)/(Enthalpy of Steam - Enthalpy of Water at Outlet)
Water Flow is the sum of maximum boiler output and blow down

Water temperature at the outlet depends on the deaerator pressure where water remains on saturation

3. Feed Water Flow Rate. Boiler maximum steam output plus a suitable design margin

Hope the above would be helpful

I forgot to add typical hydraulic loading for the vertical tray type deaerator. For preliminary sizing purpose it can be taken between 16 - 20 gpm/ft2 (0.011 - 0.014 m/s)..

Hi mansari14,

I agree that the critical Design parameters and details will not be shared by the vendor and the detailed design is done by the vendor in this case. I was doing these calculations for my self-learning purposes.

I was only looking for the sizing requirements in terms of (1) Steam flow rate requirements (ii) Feed water flow rate (iii) Storage tank volume requirement based on the boiler's rated output and blow down rate. I agree with all the details you shared and to this end I did some sizing calculations mentioned above for an project example for a pressurized deaerators. Spreadsheet is attached for your review and reference. I also want to know how the number of trays is calculated for a Spray -Tray type Deaerator. You mentioned the tray loading rates of 16 - 20 gpm/ft2. Does the steam flow rate and the diffusion rate of gas in water not play a role?.

Thanks and Regards,
Pavan Kumar