course material

1. Steam turbine report
Topic: Steam turbine reportInvestigation of losses in a Steam TurbinePower
UnitPWJ 2008, revised CD and GP 2011IntroductionThe emphasis in MIET2135 course is
on energy quality, particularly as aIDressed by the Second Law of Thermodynamics. The
course includes consideration of the thermodynamics of steam power plant.For this
experiment, a small, and therefore inefficient, steam turbine has been coupled to an
electrical generator so that the turbine can be loaded and its performance measured. By
operating this equipment and measuring and analyzing the performance of the turbine and
its associated components, you have the opportunity to learn more about steam power and
about thermodynamics. At the same time, you can develop your experimentation, analysis
and report writing skills.This particular turbine was originally designed to drive an
electrical generator to power the lighting system of a steam locomotive. Don’ t be deceived
by the simple appearance of the generator, as the steam reaches supersonic velocity and
passes through the turbine rotor twice (velocity compounded impulse type). This velocity
compounded configuration enables extraction of more of the kinetic energy than in a simple
single turbine stage.The steam is supplied by an electrically powered boiler and the exhaust
steam is condensed in a water cooled condenser. The test facility and the condenser were
all designed by students of this program.Objectives1. To become familiar with the layout
of a small steam power plant.2. For a loading condition set for you on the turbine, you will
measure the operating parameters of the turbine and the associated steam
properties3. You will then calculate energy flow through the system. How much energy do
we start with, in terms of the rate of steam energy generation by the boiler ? How much
electrical power is delivered by the generator driven by the turbine ? Where did the
majority of the energy go ?4. As an exercise in experimental report writing, each pair of
students in a lab group is required to submit a report for assessment. (Each individual in the
pair must be able, if requested, to explain all aspects of results submitted under their name.
Whilst measured data will be the same within a designated lab group, discussion and
conclusion sections of the report must be written by each pair of students independently of
the other students in the designated lab group. Any copying that is detected will attract
penalties.)ProcedureThe turbine will be started for you. You will observe several important
issues in testing a steam turbine. They include:? Recognising that the energy input to the
boiler is electrical, the main consideration for the boiler in an emergency is that the
electrical power supply is shut down by closing the main power switch. The boiler is mainly
automatic and has good monitoring and automatic shutdown if a normal shutdown is

2. required. The boiler heat input is controlled to maintain a steady saturation pressure/temp.
If these controls fail a safety valve will open to prevent excessive pressure build up. This
vents to the atmosphere outside the building. The water level in the boiler is controlled via
control of the feed pump. If the water level is getting too low the heat supply will be
stopped.? Avoiding touching hot surfaces with bare hands. The demonstrator will use
protective gloves when he has to operate hot valve handles.? There is need to keep steam
lines free of liquid, as it is desirable that the steam entering the turbine is as dry as possible.
Remember that after shutdown the system will be cold and any residual steam will
condense to water. Hence the provision of drains and blow-down facilities in order to
remove that water.? The turbine is surrounded by metal guards. All high speed machinery
should be guarded so that people do not get tangled in spinning shafts.? A governor
prevents turbine speeds from exceeding the safe speed limit of 3600rpm. This centrifugal
governor senses rotational speed and cuts back steam supply if speed is becoming too high.
To provide protection in the event of centrifugal stresses in an overspeed condition causing
turbine failure, the turbine wheel is shrouded in a thick metal casing. Recognise how to stop
the turbine, if any undesirable operating conditions arise. The main control is the valve
controlling steam admission to the turbine and that should be closed if problems
arise.? The need for a reliable supply of cooling water for the condenser. The condenser
liquefies the exhaust steam. Otherwise large volumes of steam would fill the
laboratory.When the turbine has warmed up, the operating condition will be set by the
demonstrator. When readings have reached steady values, all of the listed parameters are
to be measured and recorded.Wait ten minutes and take all the readings again. If they differ
significantly from the first set, you did not originally reach a stable condition, so take a third
set of readings, or more until you are satisfied that the condition is as stable as
possible. When you are satisfied that a good set of readings has been obtained, the turbine
should be shut down, with the aid of the demonstrator.Whilst the readings are taken, other
members of the group should prepare a flow diagram showing the main components of the
system, the steam and water flows and the location of measuring points.Other members of
the group should carry out provisional calculations of the required parameter valuesThe
“ Throttling Calorimeter” The steam generated by the boiler will be close to dry saturated
steam. As it flows through the pipes to the turbine, some heat is lost and some of the steam
condenses. Consequently wet steam enters the turbine.We need to know the state of the
steam entering the turbine, but because the steam is wet, its temperature and pressure will
not be independent of each other. Somehow we need to find the degree of wetness (or
quality) of the steam.A well known method of determining quality of steam is to use a
throttling calorimeter.If a sample of the wet steam is expanded through a valve, it becomes
superheated. When it is superheated, temperature and pressure are independent and can
be used to determine the enthalpy.The throttling process is described as constant enthalpy
(you can see why by using the steady flow energy equation). Hence you know the enthalpy
at the turbine inlet and can use it to find the quality of the steam.Parameters to be
Measured1st set of readings 2st set of readings (3rd set of readings) (4th set of
readings)Temperatures – ChannelTurbine inlet oC – 2 173 173.2Turbine outlet oC –
3 103.9 104.0Collected condensate oC – 4 65.2 65.5Calorimeter outoC –

3. 5 105.1 105.3Cooling water inlet oC – 6 21.7 21.7Cooling water outlet oC –
7 36.4 36.4Ambient oC – 8 21.1 21.2PressuresCalorimeter in – kPag (at boiler
outlet) 850kPa 860kPaCalorimeter out – kPag 0 0 0 0Turbine inlet –
kPag 790kPa 800kPaTurbine outlet – kPag 0 0Flow ratesCondensate volume –
mL 1230 1310Cond. collection time – sec 62 60Cooling water – gall/min(1 gallon =
4.55 litres) 9.8 83% 9.82 82.5%Speed / TorqueTurbine/alternator –
rpm 3000 3025Scale force reading – g 480 480Voltage / currentVoltage output /
phase to phase – V 22.8 23.2Current output / phase to phase – A 5.59 5.65Rotor
excitation current – A 0.549 0.549Rotor excitation voltage – V 7.53 7.61Note that the
lever arm of the torque balance is 250mm.On this page prepare a flow diagram showing the
main components of the system, the steam and water flows and the location of measuring
points.Calculated Results (for average readings)Calculated valueCondensate mass flow rate
– kg/sTurbine inlet specific enthalpy – kJ/kg(by using the throttling calorimeter)Inlet
steam dryness fraction(from the throttling calorimeter)Turbine inlet specific entropy –
kJ/(kg.K)Enthalpy supply rate at the turbine inlet – WCondensate specific enthalpy
– kJ/kgEnthalpy departure rate of the condensate– WRate of heat removal by condenser
cooling water – WEnthalpy arrival rate at the condenser inlet – WTurbine outlet specific
enthalpy – kJ/kg (deduced from condenser heat balance)Turbine outlet specific enthalpy –
kJ/kg (if superheated)Isentropic turbine outlet specific enthalpy – kJ/kgTurbine isentropic
efficiency – %Rate of drop of enthalpy through the turbine if isentropic– W =Rate of
drop of enthalpy through the turbine – W = ORAlternator Input Torque – NmAlternator
input mechanical power – WThree phase alternator electrical power output – W= ?3 x Vpp
x Ip x Cos ? or = 3 x Vpn x Ip x Cos ?( for resistive loads Cos ? = 1)Alternator efficiency –
%Isentropic efficiency of combined turbine and alternator – %= alter’ r elec power / rate of
drop of enthalpy through isentropic turbineSpecific enthalpy of boiler feed water at
ambient temperature – kJ/kgEnthalpy arrival rate at the boiler inlet – Wassuming feed
pump work is negligibleRate of heat aIDition to boiler – WOverall efficiency of plant, –
%([alternator elec power output]/[boiler heat rate assuming feed pump work is negligible]
)Carnot efficiency (1-TC/TH) – % (temps TC and TH in K)taking the best possible Tc to be
the cooling water inlet temperatureIdeal power output if Carnot efficiency was obtained –
W =Content of Laboratory ReportYour report should be professional and show a
technically literate reader that you are technically literate. It may help to focus your
thinking if you imagine that you are going to take this report with you to a job interview in
order to show the interview panel how good you are at thermodynamics and at report
writing.It should of course make clear what you have done in this experiment and the
significance of the experimental results. You are not asked to sanitize the results in any
way. You are asked to report on your test as clearly and honestly as possible. If the results
are not consistent, do not “ fudge” them. Instead report any inconsistencies and offer your
explanations for them.The report should be formally presented, with appropriate headings,
language and formatting. The report can include this laboratory guide and the results
tables. In aIDition the report should contain:? A Title Page including the date of the
experiment, the course name and number and the names and student numbers of the two
people writing the report.? A Summary – (aka Abstract) stating in a concise manner the

4. basic objectives of the experiment, the basic procedure and the main findings from the
experiment that relate to those objectives? A schematic sketch of the steam flow system,
showing the relationship of the measuring points to the main system
components? Calculations – sample calculations must be provided showing how the
calculated results were obtained from the measured results. Answers should be to an
appropriate number of significant figures.? An enthalpy – entropy (“ Mollier” ) diagram
(see Figure A10 in prescribed text) showingthe throttling calorimeter outletthe inlet to the
turbine (and throttling calorimeter)the outlet from the turbinethe predicted outlet from an
isentropic turbine? Discussion – Indicating any problems with the experiment,
assumptions made in the analysis, and any other information which would make the report
more meaningful to the reader. Include in your discussion consideration of the following: If
energy is neither created nor destroyed, what has happened to the energy “ lost” in this
steam power plant ? Can we still use that “ lost” energy ?? Conclusions – What are the
main results from the experiment in relation to its stated objectives ? Also, what is the
significance of these results and how do the results relate to your expectations ?Your report
is to be submitted at the SAMME reception Building 57 level 3 by 4pm, 14 calendar days
after you did the experiment.Marking Schedule:Pasted below are the published RMIT
marking guidelines that we are using to grade your reports. The marking guidelines
indicate that error free (“ competent” ) work deserves around the 60-70% range, and then
marks are allocated above or below that according to the overall quality of the work –
particular insight / synthesis / application or otherwise.It should be noted that a mark of
less than 100% does not necessarily indicate you have done something “ wrong” . It simply
means that there are ways that you could make your submitted work even better. For
example, in a lab such as this, those reports that offer discussion of interesting aspects of
the lab (e.g. why we need a calorimeter and how it works, or how the alternator fan affects
torque readings) move towards and into the HD range. Those reports that simply “ answer
the question” by presenting numerical solutions and little else, (the “ do the least amount of
work asked for” philosophy), tend to be in the 60-70% range.As you move into your senior
years at university you should become acquainted with this marking style as you will find it
being used more and more often. Our intent of course is to make you the most professional
and “ ready-to-work” graduate engineers that we can.Course Grades AvailableHD High
Distinction 80-100%Requirements: Exceptionally clear understanding of subject matter
and appreciation of issues; well organised, formulated and sustained arguments; well
thought out and structured diagrams; relevant literature referenced. Evidence of creative
insight and originality in terms of comprehension, application and analysis with at least
some synthesis and evaluation.D Distinction 70-79%Requirements: Strong grasp of subject
matter and appreciation of key issues, perhaps lacking a little on the finer points; clearly
developed arguments; relevant and well structured diagrams; appreciation of relevant
literature. Evidence of creative and solid work in terms of comprehension, application,
analysis and perhaps some synthesis.C Credit 60-69%Requirements: Competent
understanding of subject matter and appreciation of some of the main issues though
possibly with some gaps; clearly developed arguments; relevant diagrams and literature
use, perhaps with some gaps; well prepared and presented. Solid evidence of

5. comprehension and application with perhaps some analysis.P Pass 50-59%Requirements:
Some appreciation of subject matter and issues; work generally lacking in depth and
breadth and with gaps. Often work of this grade comprises a simple factual description (i.e.
basic comprehension) but little application or analysis. Work of this grade may be poorly
prepared and presented. Investment of greater care and thought in organising and
structuring work would be required to improve.N Fail 0-49%Requirements: Unsatisfactory.
Evidence of lack of understanding of subject (minimal or inadequate comprehension and
little or no application) and inability to identify issues. Often inadequate in depth and
breadth. Sometimes incomplete or irrelevant.