September 16, 2008

Excel Sheet For Steam Leak Calculation

One of the most talked about energy wasters is steam leakage from "bad" steam traps and leaking fittings. Steam traps are blamed for being inefficient or worn out and causing as much as 10% of the generated heat from steam to be lost. Is this true or just a sales method to sell more traps? It turns out that steam leaks cause a significant energy loss.

In general you can find many references where steam losses from different leak sizes at different steam pressures are listed. An example shows that a 1-inch union was found leaking at a loss of $3000 per year. The repair cost was $50 or a six day payout. So the point is whatever be the size of leaks or whatever be the pressure of steam the payback is generally in days compared to high fuel cost now a days.

If condensate is recovered, leaking traps can cause an excessive return temperature and cause failure of the condensate return pumps. Severe water hammer can occur
as hot steam contacts condensate that has cooled below the temperature of the steam

The leakage rate can be easily calculated by using general orifice equation.

Q = K x d^2 x H^0.5

Example template sheet in Excel is attached herewith for your easy use. In the said example steam of 34 bar can have a leakage rate of 17.0 Kg/hr from 1 mm hole. This is equal to Rs. 95000 / year in fuel loss. Normal repair cost can be only few thousand Rs. resulting in payback of few days/months. Therefore a regular survey of such leakage systems is necessary for every process plant.

Download Excel Sheet Here

The following steps are recommended for saving energy in your steam condensate distribution system and starting an effective steam energy management program:
  • Develop an estimate of the cost of steam leaks based upon your plant costs similar to other articles or references. A method for demonstrating visually to plant people what these losses are can be made.

  • Run a survey, recording all leaks, size, cost, and location.

  • Check the operation of all installed disc traps used for drips and steam tracing. If found leaking, consider replacing with a more efficient type trap. Before replacing, check installation design and confirm trap size (not over or undersized).

  • Check installation and operation of steam traps used on equipment using the sound detection method, the pyrometer method, or the glove method. The installation should be checked for proper trapping. Items checked include strainer, check valve, back pressure, orifice, and inert gas venting. Improper venting can cause a severe reduction in heat transfer rate.

  • Check vent valves on steam jacketed equipment and kettles for proper operation (removal of inerts without steam loss).

  • Start a preventative maintenance program to maintain the steam distribution system in excellent condition. If manpower is not available in maintenance, you can have the operating people maintain a simple log for their area of responsibility.

  • Steam trap manufacturers will be happy to furnish information to assist in your energy saving program to reduce steam losses, but use your own economic costs to decide whether to replace, repair, or redesign the system.

  • It is always beneficial to collect condensate at different pressures in different flash drums to recover flash steam
  • .
  • Also connect each high pressure drum liquid to subsequent low pressure drum

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zaki said...

It's kind of difficult to read your post when there is an amazon widget floating on the post. Can it be replace somewhere else where it won't interrupt the readers view to read your post. TQ.

profmaster said...

Thanks Zaki for your feedback
I will remove all amazon widgets from future posts, though it is working fine in IE-7.0

Anonymous said...

Your equation:

What is the "K" value.

What is the "H" value.

thank you

Davidjohn said...

Its a great pleasure reading your post.Its full of information I am looking for and I love to post a comment that "The content of your post is awesome" Great work.

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