Air Preheater Lifetime

That can depend on the environment.......... If it's a plate style preheater and the primary heat used for heating is dirty, you may have to scrub (Clean the preheater) the plates to remove the fouling.......

Otherwise you really don't give much information for us to go on

Most equipment is designed for application, and comes with a maintenance requirement recommendation..... the manufacturer should be able to supply the design life....

http://www.airpreheatercompany.com/Service/Category.aspx?cat=1&subcat=11

Dear Mr. Vandie,

Your Question is "Does anyone knows what is the expected lifetime of an air preheater?"

Life of air Pre-Heater depends upon several factors, like

1. Relative Humidity of air used for Combustion, Moisture in the Fuel burnt - these 2 factors will decide the DEW POINT and on Condenstion, PITTING and CORROSSION of Tubes and Tube Plate in the Air Pre-Heater starts.

2. Sulphur content in the fuel - forming SO3 and SO3 and H2SO4 - again CORROSSION starts.

3. Solid Particles and its Hardness in the Flue gas - leading to ABRASION/ERROSSOION.

4. Stagnation of Flue Gas or Dead Pocket in side the Heater - leading to condensation resulting in CORROSSION.

5. Quality of the Steel Material used in the Air Heater..

DHAYANANDHA.S

You forgot to mention the ratio of in-service time versus the time out of service, when all control is lost, and dew point is definitely reached. IMHO this is when 99% of the corrosion will take place.

Where I work, we have an older gas-fired (not coal) boiler unit with air preheater based on rotating drum heat exchange. The unit was installed in the early 1960's, and we still operate it. In recent years we have been utilized on a demand tag basis, with as few as 120 hours service before shut-down. In the summer months, we are fortunate to usually have a continuous tag on this old unit to help add VARS to the local grid. Fall and winter months see less service, scheduled outages for turnarounds, etc. All of the cool condition time is uncontrolled. We are seeing more rust flakes being blown out the bottoms of the air plenums. Not good.

IMHO I would not expect a pre-heater for a coal fired boiler to last even this long simply because of a higher sulfuric acid solution dew point from coal operations. Again, it depends on the environment, the process, and duty factor of the unit as much as anything, but best maintenance practices might make a small difference.

The people who originally supplied it may. For one thing, they had all the data that the organisation supplied in order to specify and quote it. For another, they may have been visiting site on a planed periodic maintenance contract. For a third, these people want repeat business.

Having worked for a company that designed and built preheaters......... as far as the life of the unit, we could never tell them that, because we could not really confirm their maintenance of the unit.......

We would design around their environment, with thing like best material selections, quality and volume of air to get the best placement of gap between the plates for easier cleaning.

But as far as life expectancy....... that can vary, with maintenance visual inspection can be for one....... but for the most part it is when the heated air is contaminated with the primary air.

Good advice for the original poster.

It's still worth a few phone calls.

Definitely, good point and wise.

Model of company where I worked does it is just one of many possible ways.

Air preheater a device that preheats the air before another process. Would be nice to know what the process is and what type of energy is being used to preheat. The other posts are for boiler preheaters. A lot of which use reclaim heat. There are other processes that need preheated air. There may not be the ability to reclaim heat. Another source of energy would be used which would be a factor in the life time of the preheater.

Since we would only be quessing on what type of preheater you are in reference to. Wouldn't it be better to ask the manufacture. They know a lot about it!

Thank you for the replies. Sorry what I meant is the life span of an air preheater in a coal based steam power plant based on best practices? In the manual they don't usually tell how long is the recommended life span as far as i know.

They will use a higher grade of stainless..... 316SS?????

And as far as life.......... they will give a approx., life........ but nothing much to hang your hat on, just due what was said earlier......

The lifetime of the preheater will be just slightly longer than the warranty period.

The duration of that window will depend on the competency of the engineering department, and the business ethics and goals of the owners of the company.

In other words, it's hard to tell.

Warranty's of preheaters is not as long as you think..... Thank god they last a heck of a lot linger then the warranty. Just due the fact if, if it was going to fail, due to workmanship, it'll fail in the first 90 days, statistically.

Competency has nothing to do with it. End user input as in maintenance plays the biggest part.

As far as performances, that has allot to do with competency.

Competency has a lot to do with any design.

Unless you are putting a roomfull of monkeys in front of a roomfull of CAD stations, competency does matter.

Yes strike that......... But the end user carries the larger weight...... You can have two exact units one last 15 years the other 5 years just due to the environment.

The point that I'm making...... With the wide area of use no one can design and fab a unit that last just over the warranty....

And secondly.... How long do you think these are warranted? It's not that long....

OK,

It's all about taking care of your equipment.

I worked for an equipment manufacturer that sold lines for hundreds of thousands of dollars and we sent field techs to keep it running. Our major owner sold the consumables that these machines used to make PCB's.

No running machine, no sales of the juice. We kept them running for them. $$$$$

Somewhere between 30 days and 30 years.

It's cuz i'm working on a long term project that requires me to know the expected life span of the critical equipments in a power plant (life cycle management). Now as far as i know, based on best practices usually a generator transformer , with good maintenance , can last at least 25-30 years without having to replace it with a new transformer. That's why i'm asking about air preheater expected life span. perhaps anyone who has experience with coal based steam power plant can help? Thx alot

Contact a manufacturer........ they give you a better prospective.

I would expect the life cycle be about the same as your vertical spindle Coal Pulverizers, depending on your PM practices or lack of. is the bottom line.