A common space for general questions, suggestions and discussions that do not fit other forums.

The member asks whether it is a good practice to use LP Heater-4 outlet initial flushing line water from another unit for boiler filling during initial cold start-up. The water temperature is around 140°C and the concern is thermal stress or related issues in a 300 MW coal-fired boiler.

A 660 MW unit is procuring flat strips for water wall welding using SA 387 Grade 12 Class 2 material. The supplier has provided a test certificate but not the heat treatment chart. The member asks whether heat treatment can be verified on the finished product by hardness or any other method, and whether IBR hardness limits for one chrome half moly material apply to this grade.

The member raises questions on colloidal silica increase in drum water, why saturated steam silica may remain low despite boiler water silica increase, possible silica slippage in ion exchange systems, and the role of WAC/WBA/SBA/MB sequencing in DM plant operation.

The member asks how a safe boiler water silica limit is determined, whether the limit can be revised based on international guidance, and how much blowdown can ideally be given through CBD/IBD arrangements.

The member seeks conceptual clarity on how suspended and colloidal impurities, though non-reactive, carry surface charges and get attracted to positively charged aluminium hydroxide flocs formed during alum coagulation.

The member reports unsafe violent steaming and truck body heating during wet handling of fly ash from a CFBC boiler, due to excess unreacted CaO reacting with water, and asks how the condition can be avoided when wet handling is compulsory.