Use
30
CHECKS AFTER COMMISSIONING
With cold start, check that:
–
the generator is filled with water up to the minimum level
–
the volume increase due to heating (thermal expansion of the water) does not excessively increase the level making draining
necessary at regular intervals to bring the level back to half scale of the glass indicator
–
once the set pressure is reached, the steam outlet valve must be gradually opened in order to heat the delivery pipe, eliminat-
ing any condensation in the ducts
–
the manhole gasket seals.
MANDATORY PERIODIC VERIFICATIONS
WATER MONITORING
The operator of the system in the installation room must frequently check the glass indicator so as that the water level in the
generator remains above the minimum value indicated in the glass level. A possible drop below the minimum value must cause
the intervention of the two safety level switches.
PRESSURE MONITORING
The operator of the system in the installation room must frequently verify that the pressure of the generator steam remains below
the maximum value indicated on the generator assembly plate; a possible abnormal increase of the pressure must cause, at first,
the intervention of the safety pressure switch, then the opening of the safety valves.
STOP PERIODS
The most serious corrosions for the generator often occur during the stop periods.
The operations to be carried out to store the generator correctly essentially depend on the duration of the downtime. When the
generator needs to be stopped
for long periods
,
dry storage
can be done. When the stops are
for short periods
or when the gen-
erator is used as a spare and must start running in a short amount of time, a
wet storage
can be made.
In both cases, the operations described below tend to eliminate any possible cause of corrosion.
When possible, wet storage reduces the time required to reach the operating conditions.
Dry storage
It is necessary to empty and dry the generator carefully, subsequently pouring a hygroscopic substance inside the cylindrical body
(e.g. quick lime, silica gel, etc.).
Wet storage
Drain the water out and clean the entire generator. Fill the unit up to the normal operating level, and after a brief period of evap-
oration it is essential to vent all the dissolved gases into the atmosphere. Then, completely fill the generator, using enough DEHA
(diethyl hydroxyl amine) to develop a residual concentration of more than 100 ppm, to prevent the attacks of oxygen dissolved in
the water. Also add trisodium phosphate, so that the overall alkalinity is greater than 400 ppm.
Then, close all the connections.
Make sure there are no leaks from the connections or joints and draw samples of water at regular intervals, to check that the
alkalinity value has not been altered.
Cooke Industries - Phone: +64 9 579 2185 Email: [email protected] Web: www.cookeindustries.co.nz
