The low pressure end of a turbine may be protected from over pressure protection by an atmospheric relief valve and/or
overspeed trip
explosion diaphragm
vacuum trip relay
vibration monitors
noise muffler
condensers may be divided into two basic groups namely,
direct and indirect
jet and surface
atmospheric and vacuum
contact and surface
evaporative and spray
Jet condensers are in limited use today mainly due to:
maintaining cooling water quality
cost
they require a large floor space
corrosion attack
all of the above
Condenser waterboxes are typically made from:
carbon steel
stainless steel
cast iron
aluminum
nickel or brass
condenser tube sheets are typically made from
admiralty brass
A large heating surface is utilized in a surface condenser for maximum efficiency. This is largely done by:
putting in as many tubes as possible
using large diameter tubes
using small diameter tubes
using stainless steel tubes
none of the above
To allow for differential expansion for the shell and tubes in a condesnser, which of the following methods may be used: 1. tube packing 2. expansion bends. 3. elastic materials 4. expansion joints to the shell 5. solid weld construction 6. slip expansion tubes
1,2
2,3
3,4
4,5
1,4
Safety fittings on a condenser may include 1. gage glass 2. relief valve 3. corrosion coupons 4. low water alarm 5. vacuum trip relay 6. leak detection devices
1,2,3,4,5
1,2,5
1,2,4,5
1,2,3,5
2,3,4,5
The main purpose of waterbox staybolts is to
support the tubesheet from cooling water pressure
support the tube sheet from condenser vacuum
prevent the condenser tubes from buckling
act as a sacrificial corrosion coupon
non condensables in a condenser must be removed largely due to
the blanketing effect on the tubes
tube pitting
increase the condensate ph
lowers the condensate ph
increases the condenser vacuum
An air ejector
increases the vacuum on a turbine condenser
prevents non-condensable gasses from entering the condenser
converts heat energy into kinetic energy
utilizes a vacuum pump
may also be termed hogging ejector
The larges single heat loss in a steam power cycle is:
latent heat of evaporation of converting water to steam
condensing steam
creating a turbine vacuum
subcooled condensate
Air that enters a surface condenser:
causes pitting on the cooling water tubes
will increase the condenser pressure
will cause the condensate to turn slightly acidic and cause corrosion
will cavitate the extraction pump
has no effect on the operation of the plant
the best test method to detect condenser cooling water leaks is
conductivitity
ph
silica
phosphate
color comparator
In a surface condenser: 1. packed tube ends allows the tube to move axially in the packing 2. deaeration is less efficient when the condensate is sub-cooled 3. there is no temperature differential expansion 4. when the inlet of the tube is exposed, it is also beaded over to prevent leakage
1,2,3
1,2,4,
1,2,3,4
Prior to starting a large condensing turbine:
the jacking oil pump is started after the turbine has been put on barring
open all steam trap bypass valves
turn on oil coolers cooling water prior to firing up the boiler
put the condenser into operation
test the turbine overspeed trips
