Posted by Vern on May 13, 2000 at 20:44:19:
In Reply to: Thermal Shock posted by Anthony Pritchard on May 13, 2000 at 14:28:53:
Question one: No. What you are talking about is a rather typical
situation. Not enough temperature differential is involved to worry about.
Question two: If an actual thermal shock did take place, I would suspect
possible tube end leakage, in extreme cases possible tube sheet damage.
Question three: Don't worry about it. Firetube boilers like yours are operated
on a daily basis with ambient degree water being fed to them with no damage.
: Regarding the qeustion of thermal shock and it's
: effects: We have (3) 400 hp firetube boilers, one
: of which we suspect has experienced a rather severe
: thermal shock for the following reasons. Upon opening
: the firsides for yearly cleaning and inspection (both
: firesides and watersides inspection) we discovered
: between 15 and 20 lbs of what appears to be scale and
: rust that obvioulsly came from the tubes (curved
: shaped debris). This boiler was operated for a number
: of days without the Deaerater Tank. The boiler water
: temperature is close to 345 deg. F, and normally with
: the DA tank the inlet water to the boiler (boiler
: feedwater) runs around 220 deg. F, however, without
: the DA tank during these few days the inlet temp.
: never rose above 150 deg. F, compound this with the
: fact that the early morning load increases usually
: result in a boiler load increase of anywhere from
: 30 to 60 percent resulting in the boiler taking a
: 'big drink' of relatively cold water.
: Question one: Is it safe to assume, given the above
: information (on a very carefully maintained boiler
: that has yet to be inspected by a certified
: inspector) that a thermal shock may have occured?
: Question two: If a thermal shock did indeed occur,
: what are the likely damages?
: Question three: How seriously should the possibility
: that a thermal shock did occur be taken?
: The possibility of a thermal shock is presently being
: brushed off as nothing to be concerned about.
: Does anyone know of any web resources that deal with
: this issue?
: If you could reply to email@example.com it would be
: much appreciated.
: Thanks in advance.
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