Heat Recovery From Sooted Flue Gas

Thanks for prompt answer.

The products of the combustion might also be something rather than soot (along with soot). Is that possible? Moreover, whatever you can do, it is still not possible to reach %100 combustion of all the fuel. Do you think that the reason why I get more soot is because I am using heavy oil (API=11-12) ??

You asked me a few questions but honestly I do not think I can accurately answer them. Could you first explain, in detail if possible, the optimal blow-down, feed water treatment regime optimization and what does top condition mean for steam delivery and lagging lines?

<...optimal blow-down, feed water treatment regime optimization and.....lagging lines...>

These are the things that need attention first, prior to the heat recovery proposal, which is going to involve significant capital equipment. They are priorities.

It would appear that they are areas for significant investigation and also learning opportunities.

let me do some search and learn about them. I think I already know some of them but I am not familiar to the terms in English.

then, hopefully, we can continue to discuss the main issue.

thanks.

I would recommend optimization of your burner first. In some cases this can be accomplished by adding water and an emulsifier to the fuel oil. In any case this is the first step, imo.

https://www.epa.gov/ttnchie1/ap42/ch01/final/c01s03.pdf

Aggie,

First, understand how your boiler works and understand how soot is wasted money.

Second, understand how the amount of excess oxygen is a measurement of the combustion process. Have knowlegeable people test this periodically

THEN AND ONLY THEN, consider waste heat recovery.

Your simplest and most effective "waste heat recovery device" is an economizer. Perform a system evaluation to detemine the impact of an economizer on your existing system. Consider the drop in steam pressure.

Get quotes for a new economizer from the original vendor of the boiler

T H E N.........

Report back to us...

I am with you on the wasted money and the economizer. I do have something to add to the "Second, understand how the amount of excess oxygen is a measurement of the combustion process. Have knowledgeable people test this periodically." The air and atmosphere around any given boiler are constantly changing. It would be best to add a boiler combustion monitoring & oxygen trim system. These systems are similar to what is in a modern car. It isn't enough to test the excess oxygen on an occasional basis because there are too many constantly changing variables. Most companies adjust for 10% excess oxygen during these periodic checks.

There have already been some good answers from people who clearly understand boilers.

I'd suggest you also calculate how much heat you could, in principle, recover using E=mc(dT)

The exhaust gas temp is fairly low, the specific heat of air is low (~1kJ/kg) and the efficiency will be low, so the energy(=money) recovered could also be low (it will depend on your circumstances).

Subtracting the cost of maintenance may mean the potential gain is zero or less. Good luck

Assuming that you still have significant soot from burning heavy oil after following the advice you've received here, a soot removal system upstream of the waste heat recovery apparatus might be adapted from this:

http://www.freepatentsonline.com/7901485.pdf

Note that the soot would be dynamically concentrated out of the flow path of the gas by a high shear process comprising centrifugation.