1. OBJECTIVES
The main objectives of this experiment are; • • •
To determine the performance characteristics of a steam plant. To demonstrate thermodynamic principles as applied to laboratory scale steam plant. To demo demons nstr trat atee the the conv conver ersio sion n of ener energy gy from from one one form form to anot anothe herr and and the the measurement of mechanical power.
2. INT INTRODU RODUCT CTIO ION N
The strength of the steam engine for modern purposes is in its ability to convert raw heat into mechanical mechanical work. Unlike the internal combustion combustion engine, engine, the steam engine engine is not particular particular about the source of heat. Since the oxygen for combustion is unmetered, steam engines burn fuel cleanly and efficiently, with relatively little pollution. ne source of inefficiency is that the condenser causes losses by being somewhat hotter than the outside world. Thus any closed closed!cy !cycle cle engine engine will will alway alwayss be somewh somewhat at less efficie efficient nt than than any open!c open!cyc ycle le engine engine,, because of condenser losses. "n this experiment, the students had been exposed with the mechanism of steam engine by using steam plant laboratory model unit. The steam plant consists of several component include include a boiler, boiler, a steam engine, engine, a condenser condenser and a feed pump. "n large power plants, steam turb turbin inee are used but for for a small small scale scale labo laborat rator ory y set set up, up, a steam steam engi engine ne is used used.. The The applications of steam engines can be divided into # categories which are as stationary engines and also as vehicles engines. $or stationary engines, its applications include in winding engine engines, s, rolling mill mill engines, thermal power stations engines and many others while for vehicles engines, its applications are traction traction engine, engine, steam aircraft, aircraft, steam rockets, rockets, steamboat, steamboat, steamship and steamship and many others.
The steam plants of today are a combination of complex engineered systems that work to produce steam in the most efficient manner that is economically feasible. "n large power plants, steam turbines are used but for a small %scale laboratory set up, a steam engine is used. "n every situation, the steam power plant must first obtained heat. The heat re&uired to produce the steam is a significant operating cost that affects the ultimate cost of end the product.
'eat is supplied to the boiler via two immersion heaters () k* each+. The water in the boiler must be clean and free from minerals. The water is pumped to the boiler from a reservoir. reser voir. The boiler raises saturated steam to a maximum bars.
- steam engine is a heat engine that performs mechanical work using steam as its working fluid. The steam engine is a totally enclosed, two cylinders, and single acting trunk piston with nominal output of #/ * at #/// rev per min. The steam is expended in the steam engine to produce useful work.
The condenser condenses the exhaust steam from the steam engine from saturated steam into water. The water is then return to the reservoir and pump back into the boiler and the cycle continues.
Figure 10 Steam motor and energy conservation test set
3. THEORY
The cycle of operations operations in a heat engine is based on 1ankine 1ankine 2ycle. The 1ankine 1ankine cycle is a thermodynamic cycle which converts heat into work. The heat is supplied externally to a closed loop, which usually uses water as the working fluid. -lmost all coal and nuclear power stati station onss use use this this cycl cyclee for for powe powerr gene genera rati tion on.. "t is name named d after after *illiam *illiam 3ohn 4ac&uorn 4ac&uorn 1ankine, 1ankine, a Scottish polymath Scottish polymath.. "t is more closely approximates to the cycle of a real steam engine if been compared to the 2arnot cycle where it predicts a lower ideal thermal efficiency than the 2arnot cycle. "n the the 1ank 1ankin inee cycl cycle, e, heat heat is been been adde added d at cons consta tant nt press pressur uree (5+ (5+,, at whic which h wate waterr is converted in a boiler to the superheated steam condition that causes the steam expands at constant constant entropy to a pressure pressure (5#+ in a condenser; condenser; the water so formed is compressed compressed at constant entropy to 5 by a feed pump. The cycle consists of four processes as been listed below0
to #0 "sentropic expansion "sentropic expansion (Steam turbine+
# to )0 "sobaric heat rejection (2ondenser+
) to 0 "sentropic compression (5ump+
to 0 "sobaric heat supply (6oiler+
Figure 20 1ankine cycle
4. MET ETHO HODO DOL LOG OGY Y
The engine was been run at the constant speed #/// rev per min ! at varying engine load with0 a+ The right hand spring balance was been loaded with # 7 stages to #/ 7 b+ The boiler pressure was varied to achieve constant speed (8 // rev. rev. min!+
The parameter was recorded in the data sheet (The volume of condensate was collected in a measuring cylinder with minute9s interval for the condensate flow rate.+ The results were been analy:ed.
-fter used0 a+ The electrical and water supplies were disconnected b+ The boiler was allowed to cool down down and the boiler drain valve was opened c+ The water from the apparatus was drained d+ The temperature display was switched off. 7ote0 7ever open the boiler drain valve while there is a pressure or high temperature inside the boiler.
5. RESU RESUL LTS
T!"e 10 1esult that obtains for the different spring load.
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Figure 2; The graph steam flow rate vs power output.
<. DISCUSSION
This experiment purposely conducted to make a study on the steam plant operation and performance in terms of thermodynamic and heat transfer concept. There are # different spring loads that re&uired adjusting in order to observe the significant on the power output of the engine. $or this experiment, $# is maintaining at ./7 while the $ adjusted by the increment of /.<7 in intervals. The 6oiler 5ressure and Temperature readings were taken throughou throughoutt the experiment for the steam &uality &uality and boiler efficiency efficiency calculation. calculation. There are others others parameters parameters that being recorded recorded such as Cngine Cngine "nlet 5ressure and speed, 2alorimeter 2alorimeter Tempera emperatur ture, e, 2onden 2ondenser ser 2oolin 2ooling g *ater ater "nlet "nlet Tempera emperatur ture, e, 2onden 2ondensate sate $low $low rate and Temperature as well as the Clectrical 5ower supply to the unit. The experiment carried out until the engine stop running when the load increases.
$or the first run, the $ load was set at .<7 and the 6oiler operating condition recorded at =/ bars and #>D2. 6y calculation, the steam &uality produced was observed at /.>> with the boiler efficiency of about @/.>> E. The power delivered by the engine calculated to be
=./@<* with the 1ankine cycle efficiency observed at .@< with the thermal efficiency indicated at ./@ x / !). 6y referring to the steam &uality produced, there is almost a perfect water vapor phase existence.
The spring load of $ was set at #./7 and the steam &uality produced was calculated to be /.>> at )#.= bars and )#.=D2 of boiler condition. The boiler efficiency was above than perfect condition in operation, which calculated at @?.
The third run observed observed the steam steam &ualit &uality y produ produced ced at /.>??.))E and the 1ankine efficiency observed at ).>?=. The engine power output measured at ?.) * with the thermal efficiency recorded at ).=# x / !). The fourth run with the $ load set at )./ 7 measured the boiler efficiency at ?/.= E with the steam &uality produced monitored at /.>@>/. The The power generated by the engine recorded at #).>@ * with the thermal efficiency calculated at .)# x / !)and the 1ankine efficiency of<.)=.
The steam &uality recorded at /.>>/ /.>>/ with the boiler efficiency efficiency calculated at /#.)E at $ set to ).< 7. The power output of the engine measured at #>.?)/* while the efficiency of thermal observed at <.# x / !) and the 1ankin 1ankinee was at <./)=. <./)=. The boiler efficien efficiency cy measured at ><.=>E and the steam produced was calculated at /.>>// when the $# set at ./ 7. This causes the engine power to produced )<.< * with the thermal efficiency measured at =./ x / !) together with the 1ankine cycle of =.)> efficient. The seventh run was observed observed with the $ set at .< 7. The efficiency efficiency of the boiler measured measured at >>.@)E >>.@)E with the 1ankine recorded at @.) and the thermal was calculated at @.#>/ x / !). $or this run, the steam &uality generated was calculated at /.>?=/with the power of the engine recorded at #.#=*.
The last run carried out with the $# load was set at <./ 7. The steam produced was calculated at /.>?/ with the power delivered from the engine measured at @.#>/. This experiment recorded the efficiency of boiler at /.<@E, the 1ankine efficiency at ?./) and the thermal efficiency at ?.
Since the increasing of the $ and constant value of $#, the boiler efficiency is increasing. The basic idea to increase increase the efficiency efficiency of the 1ankine 2ycle 2ycle is increase increase the temperature temperature at which heat is transferred to the working fluid in the boiler or decrease the temperature at which heat is rejected from the working fluid in the condenser condenser.. "n this steam plant, there are three ways to increase efficiency based in simple ideal 1ankine 2ycle which is lowering the 2ondenser 5ressure (Fower T
+, lowering the operating pressure of the condenser which
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$rom the data and results obtained, crystal clearly shows the power output from the engine is increasing by the increment of the spring load difference. 'igher load also lead to higher boiler efficiency with a direct relation to the 1ankine and thermal efficiency as well.
=. CONCLUSION
6ased on the result, there is a proven that the steam plant can produced a high &uality of water vapor mixture, which is around >>. E. $rom the relationship, there is significant increment on the power input of the engine when the load is increasing. Thus, we can conclude that the higher the load, the higher the power output from the engine. This direct relationship also linked to the boiler, 1ankine and thermal efficiency which the higher the load, the better the efficiency.
>. REFERENCES
-. 3ack *inn *innick ick , 2hapter 2hapter @, 5ower 5ower production production,, Chemical Engineering Thermodynamics (1997), pg.=>. (1997), pg.=>. 6. *oodruf *oodruff. f. C. 6.et.al.(#/ 6.et.al.(#//<+. /<+. Steam Plant Operation. 4cGraw Operation. 4cGraw 'ill. 2. 2eng 2engel el.H .H.. -. -nd -nd Turne urnell 1.'. 1.'. (#//<+ (#//<+.. Fndamentals o! Thermal Flid Sciences. 4cGraw'ill 'igher Cducation. A. 5ott 5otter er.. 4. 2. -nd Scott Scott.. C. 5. (#// (#//+. +. Therma Thermall Scienc Sciences" es" #n $ntro $ntrodc dctio tion n to Thermodynamics, Flids %echanics and &eat Trans!er. Trans!er. Thomas Thomas Fearning. C. 1ous 1oussea seau. u.S. S.F. F.(# (#// //)+ )+.. Steam Tr'ine " # oo $nto &o* # Steam Tr'ine Fnctions . Technical Technical 1iview
?''ENDI8
?. S?M'LE S?M'LE C?LCUL? C?LCUL?TI TION ON FOR LO?D LO?D
[email protected] [email protected]
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