At BMS logic the burner go to trip if the fuel pressure reach minimum pressure.

1)why? and 2)How this minimum value of pressure is calculated?

 

Fuel flow-rate can be related to pressure. If there's not enough pressure, there won't be enough flow. If fuel flow is low, then there isn't going to be much flame and it's possible that the flame will be extinguished by any air flow in the "boiler" (or wherever the burner is located), or, at a minimum the flame may be unstable, which is not desirable, either.

Also, if the fuel pressure is less than the pressure in the "boiler", there will be flow in the reverse direction, into the nozzle instead of out of it.

The manufacturer of the nozzle usually specifies the minimum fuel flow pressure.

 

First, it is important to understand that the BMS (burner management system) is first and foremost a SAFETY SYSTEM. Design and requirements of it are usually dictated in fire protection code (NFPA in the USA).

The BMS exists to prevent boiler explosions and other bad things. It's second purpose is to control the burner system. PRIMARY PURPOSE: SAFETY

With that said, you have a trip on low burner pressure for this reason: As CSA said low burner pressure can (and usually will) lead to the fire going out. If the fire goes out on that burner and fuel continues to flow, you are entering a dangerous situation which could cause an explosion.

Another problem is lower burner pressure will most likely lead to poor fuel atomization. This can cause many problems including flame impingement, explosions (that word keeps coming up), and grumpy people.

 

Krush... are you (or anyone else) interested in how a toilet-leak caused failure of a PLC-based BMS "protecting" a 12-story boiler, and initiated an $800,000,000 lawsuit? If so, contact me off-list!

Regards, Phil Corso (cepsicon[at]aol[dot]com)

 

Thanks, your note is useful for me.

 

Masoud... repeating an earlier Caveat, "I won’t accept anonymous requests for information or help... something to do with the fact that anonymity breeds boorishness!"

Therefore, anyone seeking advice or help must go the extra mile, i.e., provide me with some personal information. All I ask is that you provide your full name, your affiliation with a company (or school), and your location!

In return, if wanted, I will send you a resume of my qualifications and experience... an abridged or complete version!

Regards, Phil Corso (cepsicon [at] aol [dot] com)