4 replies to this topic

[jordan1111]

Good morning everyone,

 

Our facility is currently experiencing barometric condenser and air ejector issue. I attached a document that includes two simiplied drawings of our condenser (direct contact condenser) and air ejector including all the operating conditions. In the first drawing(summer), the data was just captured recently with cooling water temperature of 15.5 DegC through the barometric condenser. In the second drawing (winter), the data was captured 1 month ago with cooling water temperature of 5.5 DegC through the barometric condenser. 

 

We have the same amount of cooling water flowing through barometric condenser each day (3000 Imperial GPM), and inlet vapor/steam of 53 Imperial GPM or 31800 lb/hr. The inlet and outlet cooling water temperature are shown on the attachment. 

Based on the energy balance, winter time has excess of cooling water and summer time does not have enough cooling water. 

The barometric condenser vacuum is 0.94 inHgA in the winter and 1.35 inHgA in the summer. 

Now if we look at the air ejector, the suction pressure in the winter is 1.24 inHgA and 0.55 inHgA in the summer, which tells me there is less non-condensables+water vapor being ejected in the summer. The second stage air ejector suction pressure is almost the same in both winter and summer.

 

Barometric condenser vacuum is the summer of water vapor pressure at the tail temperature + partial pressure of non-condensables+water vapor. The tail temperature is only 1 degC different compared summer and winter. 

 

My question is why in this case, the barometric condenser vacuum is way smaller in the summer time compared to winter? Higher partial pressure of non-condensables? But suction pressure in the summer time is less? Is it related to the specific volume of steam and air? in the summer time, less air is entrained in the cooling water and due to the energy balance, the cooling water is not condensing 100% of the vapor, and the specific volume of steam is way higher than air, this might be the reason?

 

Thanks everyone.

 

Attached Files

•  0232_001.pdf   203.61KB   32 downloads

[katmar]

A heat balance based on the flow rates that you have given suggests that the cooling water temperature should rise by 10°C in passing through the condenser. The fact that it rises by only 5.5°C in summer but by 14.5°C in winter tells me that in summer you either have a much higher flow of cooling water or a much lower steam load coming into the condenser. Either of these would explain why you are able to achieve a deeper vacuum in summer.

[Bobby Strain]

Your drawing numbers are not very easy to decipher. But Katmar's conclusion is correct. You have data to decide which is the correct conclusion.

 

Bobby

Edited by Bobby Strain, 05 May 2022 - 12:51 PM.

[jordan1111]

Thank you Bobby and Katmar. 

We will have new instruments installed this May to verify some of those numbers.

 

I greatly appreciate your help!

[breizh]

Hi,

Make sure your equipment are calibrated before replacing them . It could be very tricky to get good data . Consider to purchase a portable vacuum meter to validate your readings . This is based on my experience .

Good luck

Breizh