boiler operations

You can google any one of these questions yourself, but:

1 results in 3 + dirty and inefficient trubines etc.

2 silica = sand = insoluble deposits on turbine blades etc

3 is result of 1

4 Nasty suff - bad for atmosphere.

May I ask if the boiler attendants are still working at this place?

Had they ever heard of boiler water testing............and they certainly knew nothing about blowing a boiler down........or was the blowdown valve seized.

When was the boiler last examined internally.............and externally for that matter?

It all sounds like an accident waiting to happen.

In the RN almost 50 years ago we checked the feed water both chemically and electronically for a clean water....even a few parts per million meant that at best the boiler feed water could only be used for freh water drinking washing etc....

I am sure the RN was not doing this "just for fun" to find chloride, it probably damages things!!!

<...1. what will be consequences if CHLORIDE is reported in super heated steam?...>

The only way that the chloride ion can appear in the steam system is if the boiler is priming and boiler water is being carried over into the steam pipework. If water is present there, then the superheaters cannot be working, therefore there are three possible problems suggested by the query:

1. The boiler is priming, indicating it is being badly run, being overdue for a blowdown and/or being operated at too high a water level
2. The superheaters aren't working.
3. The reporting system is generating gibberish, which may be a consequence of the operator training that is suggesting the other two.

<...2.what do mean by silica vapourization in boilers ?...>

Silica is soluble in steam and will glaze-out on heat exchange surfaces when the steam is supplied to the end user. Silica will reduce the user equipment's heat exchange effectiveness over time and will, in extreme circumstances, cause mechanical failure of:

1. components rotating in the steam (generator turbines? Condensate return pumps?)
2. Steam traps

both of which have a negative economic impact as well as safety implications for poorly-maintained equipment. Therefore the feed water to most high-pressure boilers has to be low in silica. Silica analysers are used to measure it, and feedwater treatment plant is used to remove it.

<...4 Detail description of NOX and SOX formation in boilers with related chemical equations....>

They don't happen within the boiler itself; they are formed in the combustion space.

These products are the reaction of nitrogen and sulphur present in the fuel, and to a certain extent atmospheric nitrogen, with oxygen in the combustion space to give these unwanted products in the exhaust gases, introducing strong smells. They dissolve in water to make acids, which can have a corrosive effect over time to the flue and the combustion heat exchange surfaces, reducing the life of the boiler.

SOX and NOX can be minimised by competent boiler operation.

See Wikipedia for a more detailed explanation that includes the chemistry involved.

Two of the questions would appear to be linked in that Chloride carried over in the superheated steam will eventually end up causing stress corrosion cracking of the turbine blades generally at either the blade root or at the tang I would surmise. After you start throwing some blades due to some moisture carryover because your water level is too high like the man said and priming causes more moisture in your steam than the superheater can handle or your superheater tubes are glazed over with minerals that should never have been there you can dismantle what's left of the turbine and discover what stress corrosion or caustic embrittlement can do to a highly tuned machine like a steam turbine.

You probably should also be checking your BFW for O2 as well because if you're getting Chloride into the steam and have a high O2 level you're going to have some major tube cracking problems probably around your headers.

Like the man said what kind of water testing are you doing and what are using to maintain proper BFW make-up and what inhibitors are you adding?

All great answers, gents, but I wouldn't worry about the equipment. This really sounds like homework in a boiler chemistry course.

Have a look at this site from GE:

Handbook of Industrial Water Treatment

http://www.gewater.com/handbook/index.jsp

hope this help

S

corrosion & rust prevention