5 Bottom Blowdown
Page 86 Mk8 MM Expansion Features Installation and Set-Up Guide 04.09.2016
5.2.2 Calculation for Bottom Blowdown Reduction
For timed reduced bottom blowdown with M.M. the maximum steam production used to base how the
bottom blowdown time is scaled down to, is set through expansion option 36.4. The blowdown time is
reduced according to the ratio of the actual steam production to the maximum steam production for
that period. If the blowdown is calculated above the stored blowdown time set by the user in the
bottom blowdown screen, than the extra time will get carried over to the next timed blowdown. This
extra time will remain getting carried over to the following blowdowns until the steam production has
lowered and the blowdown is therefore lowered.
There can be up to 4 blowdowns over a 24 hour period, with each blowdown:
Blowdown Time BD
1 BD2 BD3 BD4
Time between Blowdowns T1 T2 T3 T4
The configured blowdown time for that period x which has been set by the user is:
sec
The time between the blowdowns which is sent by the user is:
Therefore over a 24 hour period:
24
The blowdown time for that 24 hour period is then:
So the maximum blowdown period can be calculated as:
24
The maximum steam flow which is set in expansion option 36.4 is:
The average steam flow for that period which is given from steam flow metering is:
The calculated steam flow ratio for that period is then:
The adjusted blowdown time according to steam production is then:
24
If the adjusted blowdown time is calculated higher than the maximum blowdown time, the time is
carried over to the next blowdown operation:
Extra time is carried over to next blowdown operation
If the adjusted blowdown time is calculated lower than the minimum blowdown time set in expansion
option 36.3, and expansion option 36.2 is set for minimum blowdown enforced then:
, then Minimum blowdown time is enforced
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