Low NOx Burner or SCR for Boiler? 1

[PW888]

We have a 15-M Keystone (O) Type package boiler made by ERIE CITY IRON WORKS. Its steaming rate is approx 60,000~70,000lb/hr. Its flue gas temperature is approx. 570 degree F.(assumed) The fuel is natural gas. We use it as a back-up and it is not operated frequenty. Our goal is to reduce its NOx level.
I received two options. One is to install a low NOx burner with new FD fan and control system, like Rapid Mix Burner (RMB). The other one is to use Selective Catalytic Reduction (SCR). We installed RMB at somewhere else before and it worked. SCR is new to us and we are not familiar with it. But SCR seems to be cheaper and easier to install.
I wonder if you can give me some suggestions about the PROs and CONs of each option.
Thank you in advance for your opinions.

 

[rmw]

With the burner, you are just reconfiguring how you do your actual combustion, and all you have to worry about is having your flame too close to metal parts in your boiler.

With the SCR, you have the cost of the catylist and the associated duct modifications to accomodate it, but you have the day in and day out expense of the ammonia plus the worry of ammonia slip if you get too much of it.

I've seen it done both ways, and there are pitfalls to each one. Since this is not your main boiler, I'd let capitol cost considerations make the decision.

rmw

 

[PW888]

Thank you RMW.

Our goal is to reach 0.011 lb/MMBtu (~9PPM) NOx emission rate. So basically we have to use Ultra-Low NOx burner. After search, I found there are several manufacturers, such as, John Zink (TODD RMB Burner), COEN (QLA Burner), NATCOM, and ALZETA (CSB Burner). Do you guys have any experience or recommendations about some specific burners?

Thanks.

 

[ApC2Kp]

PW888,

Client replaced an old Erie City boiler with another boiler brand 'N' fitted with low NOX burner. There was not a turndown provision for controlling the secondary air to the burner. When the boiler was attempted to be run at lowest rate, the flame front became unstable. It would travel from burner at the boiler front to the back wall of boiler, and then reverse to the front. Boiler casing would shake at each reversal of flame front. It could be observed by others through sight ports at the burner platform . (I was not there!)

Conclusion: It may not be the basic technology, but the refinement of the process and its controls that determines which technology best suits your needs. If this is a backup boiler with need to turndown with low loads, then get performance guarantees for turndown capability.