The Important Of Energy Efficient Engineering Essay

The Important Of Energy Efficient Engineering Essay

Energy efficiencyA isA anA actionA that usesA really littleA energyA to accomplishA the sameA undertaking. Efficient usage of energyA willA showA the rate ofA energy nest eggs andA less moneyA spent on the energy. EfficientA usage ofA energyA in theA electricA power stationA willA provideA legion benefits toA the stationA andA besides for worlds and natures. The benefits are in term of operating cost, environments protection, and prolonged the supply. There are many manner to increase the overall efficiency of steam power works. One of the ways is by cut downing the steam force per unit area in the capacitor. This can be done by take downing the capacitor temperature by go arounding lower temperature medium such as sea H2O into the capacitor. Energy is required to go around the chilling medium into capacitor. Therefore, to cut downing the capacitor force per unit area the energy that needs to go around the chilling medium demand to be addition. The addition in energy usage for pumping the chilling medium into the capacitor has become a concern since the intent to increase this energy is to increase overall efficiency of the works and bring forth more energy in the turbine. Therefore, optimum government of the capacitor force per unit area demand to be find so that by cut downing the capacitor force per unit area to the optimum degree, it can increase overall efficiency of the steam power works to the optimum degree.

Problem Statement

Electricity is so importance because it runs everything in our mundane life. Electricity helps us to pass on, travel from one topographic point to another and besides to bring around some of diseases. The usage of electricity has increased by twelvemonth to twelvemonth due to the increasing in homo ‘s population and industrial revolutions. This has force us to bring forth more electricity to carry through the demand for electricity. Most of the electricity is generated by utilizing unrenewable energy beginning such as fossil fuel and coal. The power works that generate electricity on this beginning is known as steam power works because of steam is being generated in the boiler whereby energy from the beginning is used to alter H2O in the boiler into steam.

Procedure to pull out the energy from the beginning has produce unsafe gases that can harm the environment. Therefore, to increase the sum of electricity generated, the sum of beginning demand to be used besides necessitate to be increased and by that, the sum of unsafe gases besides will increase. However, there is a solution for steam power works to cut down the sum of pollution and increase the sum of electricity generated at the same clip. The solution is to increase the overall efficiency of the steam power works. This can be achieved by take downing the steam power works capacitor force per unit area.

When capacitor force per unit area decreasing, the heat that need to be taken away addition which demand more circulation of chilling medium in steam power works chilling system. Eventhough by addition the energy in works chilling system can increase thermic efficiency of the works ; the overall efficiency of the steam power works can be reduced. Hence, optimum working force per unit area demand to be find so that by increasing the energy in chilling system, the overall efficiency of the works can be addition.

Aim of Undertaking

The aims of this undertaking are to:

Study the effects of cut downing capacitor force per unit area to the overall efficiency of steam power works.

Study pumping power required to go around cooling H2O to take downing the capacitor force per unit area and its effects to overall efficiency of steam power works.

Obtain optimum capacitor force per unit area that is required to increase overall efficiency of steam power works.

Scope of the Undertaking

This undertaking will be focus on steam power works that operate utilizing Regenerative Rankine Cycle consist one unfastened and closed provender H2O warmer correspondingly. Plant ‘s pump and turbine is considered to run at 100 % of efficiency which means there are no irreversibility in both pump and turbine. Plant operates based on Ideal Rankine Cycle in force per unit area between 160 Bar to 0.1 Bar. X Steam excel spreadsheet with IAPWS IF97 Steam Tables macro embedded inside the spreadsheet will be used to find parametric quantities such as information, heat content, temperature and force per unit area. Overall works efficiency is determined by utilizing following equations.

Chapter 2

LITERATURE REVIEW

Introduction

Steam power works produce electricity from beginning such as dodos fuel and coal by firing the beginning in furnace and utilize the heat to bring forth utile energy that can used to bring forth electricity. Steam power works that operate utilizing firing fuel such as oil, and coal release unsafe gases such as CO2, SO2 and NOx into environment. These gases have become a pollution that harms our environment. In order to cut down the pollution, steam power works demand to be operated at its best efficiency. Overall efficiency of steam power works can be increased by bettering steam power works system such as by bettering turbine recess temperature, bettering air to fuel assorted ratio in boiler, and take downing capacitor temperature.

The Important of Energy Efficient

Coal power workss are the among biggest air defilers in the universe. It is a concern to us since the demand for electricity is increase and so therefore the sum of gases that released by steam power works. In Malaysia, coal ingestion for electricity coevals grows at rate of 9.7 % per twelvemonth, and is expected to increase well to run into energy demand. The lifting in energy demand is influenced by strong demand for the industrial sector, which increases at 5.4 % yearly. For residential sector, energy demand growing at rate of 4.9 % per twelvemonth [ 1 ] .

Figure 2: Energy production ( kilo Ton of oil equivalent ) obtained from International Energy Agency ( IEA Statistics A© OECD/IEA, hypertext transfer protocol: //www.iea.org/stats/index.asp ) .

Figure 2: Carbon dioxide released in Malaysia obtained from Carbon Dioxide Information Analysis Center, Environmental Sciences Division, Oak Ridge National Laboratory, Tennessee, United States.

As can be seen in figure 2-1 and figure 2-2, the degree of energy produced and CO2 emanation is increasing. The CO2 that released by steam power works has pollute our universe and therefore something must be done to protect our environment. Increasing overall efficiency of steam power works can assist to cut down CO2 gas emanation and planetary heating.

Gass that released by steam power workss non merely pollutes the environment, it besides bounces impacts to human ‘s wellness. Opposing Coal Power Group, 2009 [ 2 ] province that the gases released by steam power workss have effects to human ‘s wellness. The exposure to the gases can impact tegument, lungs, bosom, kidney, reproduction, and behavioral. Some of the diary province that there is even decease cause by pollution that is created by steam power works.

Augmentation in overall efficiency of works can besides assist the works to cut down the operating costs. This is because the sum of electricity that generated can be increased if the works operates at its highest efficiency. Therefore, the works can cut down the costs of bring forthing the same sum of electricity. This cost is including the cost to buy beginning such as fossil fuel and coal. With the betterment of the works efficiency, demand for electricity can be fulfill without have to increase the sum of dodo fuel, and coal. This besides will protract our energy beginning so that it can be used in a long clip.

What People Has Done To Increase Their Plant Efficiency

Literature hunt has been done to detect what people have done to increase their works efficiency. It was observed that there are a batch of methods that can be done to increase overall efficiency of steam power works. Their studies have been read and summarized in this subdivision.

Bellman [ 3 ] provinces on his study that efficiency can be better through ;

“ Operational Practices – Efficiency can be improved by pressing over fire air to the lower limit, to the full using heat integrating systems, and remaining after steam leaks and money changer fouling. Operating at full burden capacity continuously will heighten efficiency. ”

“ Fuel – Coals the higher superior coals enable higher efficiency because they contain less ash and less H2O. ”

“ Pollutant control – The degree of pollutant emanation control ( including thermal ) effects efficiency. NOx decrease units and SOx scrubbers represent parasitic tonss that decrease net coevals and therefore cut down efficiency. ”

“ Ambient conditions – Colder H2O and ambient air achieves higher efficiency.Additionally, higher heights have lower ambient force per unit area which affects compaction and enlargement. The power end product loss is a map of the loss in ambient force per unit area. All else equal, lower height enables higher efficiency. “

( David K. Bellman, July 18, 2007 )

Nichols [ 4 ] province in his study, “ efficiency betterment methods were identified for most power works constituents or systems. Advanced procedure control systems – peculiarly burning controls and furnace sootblower controls – have become popular picks to better power works efficiency. Another recent betterment to increase works efficiency is the usage of coal drying for workss that use low rank coals. Nichols besides summarized the informations that his collect in Table 2-1 for scope of efficiency betterment public presentation for assortment power works components/systems obtained from his literature hunt.

Table 2: Plant betterments with their efficiency addition.

Plant Improvements

Efficiency Increase ( per centum point )

Air Preheaters ( optimize )

0.16 to 1.5

Ash Removal System ( replace )

0.1

Boiler ( increase airheater surface )

2.1

Combustion System ( optimize )

0.15 to 0.84

Condenser ( optimize )

0.7 to 2.4

Cooling System Performance ( ascent )

0.2 to 1

Feedwater Heaters ( optimize )

0.2 to 2

Flue Gas Moisture Recovery

0.3 to 0.65

Flue Gas Heat Recovery

0.3 to 1.5

Coal Drying ( Installation )

0.1 to 1.7

Procedure Controls ( installation/improvement )

0.2 to 2

Decrease of Slag and Furnace Fouling ( Mg hydrated oxide injection )

0.4

Sootblower Optimization

0.1 to 0.65

Steam Leaks ( cut down )

1.1

Steam Turbine ( refurbish )

0.84 to 2.6

Hasler [ 5 ] has done a survey on assorted methods to cut down the heat rate of bing coal-burning power workss in United States in scope of sizesa?’200 MW, 500 MW, and 900 MW. He shows in his survey that efficiency of the system and equipment can be improves through the undermentioned ways ;

“ Major steam turbine alterations, such as replacing of rotors, blades, noses, seals and inner and outer shells. ”

“ Major boiler alterations. ”

“ Control systems ( digital, on-line public presentation monitoring, etc. ) . ”

“ High-efficiency motors on all major revolving equipment. ”

“ Variable-frequency thrust ( VFD ) motors on all major revolving equipment ( normally improves. ”

“ Efficiencies at lower than full burden ) . ”

“ Other alterations known to ensue in significant equipment and system efficiency additions and works heat rate decreases. ”

( Hasler, January 22, 2009 )

Another efficiency betterments undertaking has been conducted by National Energy Technology Laboratory ( NETL ) . Their method is to utilize waste heat to dry lignite fuel. It is well-known that lignite fuel consist 40 % of wet. The sum of efficiency that can be increased is approximately 4 % to 5 % by cut downing the wet content about 10 % . The undertaking director, Gollakota [ 6 ] said in his study that “ engineering could be applied to increase the generating capacity, efficiency, and cost-effectiveness of units that burn high-moisture coal. ” ( Gollakota, April, 2011 ) .

Bettering Efficiency by Reducing Condenser Pressure

Overall efficiency of steam power works can be increase by take downing capacitor force per unit area. Condenser force per unit area can be reduced by take downing its temperature. This can be done by go arounding sea H2O inside capacitor to cut down the temperature of the capacitor. Cengel [ 7 ] provinces that take downing the capacitor force per unit area can increase the sum of net work end product, and increase the overall efficiency of the works. This can be illustrated in the figure 2-3. The ruddy shaded part in figure 2-3 show the sum of utile work. By cut downing the capacitor force per unit area from sum of net work end product increased and heat input demand besides increase but this addition is really little. Therefore, the overall consequence of take downing the capacitor force per unit area is an addition in thermic efficiency.

.

Figure 2: Consequence of cut downing capacitor force per unit area, obtained from text book ( Y. A. Cengel and M. A. Boles, Thermodynamics: An Engineering Approach, 5th erectile dysfunction, McGraw-Hill, 2006 )

Lowering capacitor force per unit area has increase the sum of heat demand to be taken off in the capacitor. Thus the energy required to go around cooling H2O into capacitor addition. The addition in energy to go around the chilling H2O can cut down the overall efficiency of the steam power works. Therefore optimum on the job force per unit area of capacitor demand to be determines. The optimum force per unit area can be determined by ciphering the difference between alterations in turbine energy generated, with the alteration in energy usage for pump in works chilling system

Chapter 3

Methodology

Introduction

This chapter will explicate the information about the procedure bring forthing energy base on Simple Rankine Cycle and besides the rhythm that it used for this survey which is Regenerative Rankine Cycle. The works that used for this survey is fundamentally have one unfastened and closed feedwater warmer correspondingly. Furthermore the chilling system besides will be discus in this subdivision so that the relationship between works capacitor and chilling system is known. It besides describes the method that will be used to find the optimum operating status for capacitor to increase overall efficiency of the works.

Procedure Flow Chart

Figure 3: Flow chart of the undertaking.

Ideal Rankine Cycle

Basically there are 4 constituents in vapor power rhythm ( Rankine Cycle ) , which are pump, boiler, turbine, and capacitor. The procedure of the rhythm can be shown as in the figure 3-2 below and the corresponding procedures are as below ;

Four procedures involve in Rankine Cycle ;

1-2 Isentropic compaction in a pump.

2-3 Constant force per unit area heat add-on in a boiler.

3-4 Isentropic enlargement in a turbine.

4-1 Constant force per unit area heat rejection in a capacitor

Figure 3: Working Principle of an Ideal Rankine Cycle obtained from text book ( Y. A. Cengel and M. A. Boles, Thermodynamics: An Engineering Approach, 5th erectile dysfunction, McGraw-Hill, 2006 )

Water enters the pump at province 1 as a concentrated liquid and compressed isentropically to province 2 where force per unit area has reach boiler force per unit area. In this procedure, the temperature of H2O somewhat increases due to diminish in specific volume of H2O. Water enters boiler as a tight saturated liquid at province 2 and leaves as a superheated vapour at province 3. Boiler is fundamentally heat money changer where H2O been heated up to superheat temperature by burning gases such as coal and fossil fuel. The superheated vapour at province 3 enters the turbine and use isentropically. Superheated vapour hit turbine blade and therefore cause shaft that connected to turbine rotate as good. This produced utile work that used to bring forth electricity. The force per unit area and temperature of the vapor bead as it leave turbine at province 4 and enters condenser. Steam enters the capacitor at province 4 as a concentrated liquid-vapor mixture with high quality. Steam condensed at changeless force per unit area in capacitor which is fundamentally a heat money changer, by rejecting heat to a chilling medium. In the T-s diagram in figure 3-1, heat transferred to the H2O in the boiler is represented by country under procedure curve 2-3 and heat rejected in capacitor is represent by country under procedure 4-1. The different between these two represent the net work green goods during the rhythm.

Ideal Regenerative Rankine Cycle

Many of the steam power workss today operate by utilizing Regenerative Rankine Cycle. Regenerative Rankine Cycle is fundamentally enhancement of Ideal Rankine Cycle. It is known that in Simple Rankine Cycle, the heat add-on is low at point 2 ( fig 3-2 ) . To get the better of this job temperature of H2O can be increase before it enters boiler. Temperature of liquid that go forthing the pump ( called feedwater ) before it enters boiler can be increased by reassigning heat to the feedwater from the spread outing steam in a counterflow heat money changer physique in the turbine whereby the procedure is known as regeneration procedure. However this is impractical to make in works because of edifice heat money changer in turbine is hard and it will increase wet content which cause turbine blade to gnaw by the moister. A practical regenerative procedure in steam power works is done by pull outing or shed blooding steam from turbine at certain force per unit area and temperature. Device used to for regeneration procedure is called as Regenerator of Feedwater Heater. Feedwater Heater is fundamentally a heat money changer whereby heat is transfer from extracted steam to feedwater either by blending the two fluids ( called open feedwater warmer ) or without blending them ( called stopping points feedwater warmer ) .

Open feedwater warmer is fundamentally a commixture chamber where steam extracted from turbine is assorted with feedwater go forthing the pump. The mixture leaves the warmer as a concentrated liquid at the warmer force per unit area. In closed feedwater warmer heat is transferred to the feedwater from extracted steam without blending them. The two steams now can be at the different force per unit area since they non assorted. The extracted steam mass flow rate can be calculated by presuming measures of steam leaves the boiler is at 1kg. From 1kg of steam, Y kilogram is expends partly in the turbine and the staying ( 1-y ) kilogram is expends wholly to the capacitor force per unit area. Therefore, mass flow rate is different at each constituent. Therefore, mass flow rate for each constituent can be determine by ciphering the steam mass fraction and so multiply it by mass flow rate of steam before steam being extracted which is at point where steam leaves the boiler.

Steam Power Plant Used For This Survey

To simplify this survey, a simple steam power works consists of one unfastened feedwater warmer and one closed feedwater warmer will be use. The procedure diagram of the works is shown in figure 3-3. Steam from capacitor enters pump 1 as a concentrated liquid and compressed to boiler force per unit area. Then, steam that leaves pump 1 is heated by extracted steam from turbine to the temperature of the extracted steam. In existent power works system, the feedwater leaves the warmer below the issue temperature of the extracted steam because a temperature difference at least a few grades is required for any effectual heat transportation to take topographic point. The extracted steam compressed to the boiler force per unit area by pump 2 and assorted with steam that leaves closed feedwater warmer. Both assorted steam enters boiler and being heated to superheat temperature. In turbine, y kilogram of the steam is spread outing partly and the steam is used to heat feedwater that leaves pump 1. Another ( 1-y ) kilogram of steam is expend wholly in turbine and leaves as a concentrated liquid-vapor mixture before enters condenser.

Figure 3: Steam Power Plant for this survey

Sea Water Cooling System

To cut down the capacitor force per unit area, heat demand to be rejected from the steam that enters the capacitor. This can be done by go arounding sea H2O into the capacitor. For this survey, direct heat rejected chilling system will be used and the corresponding flow diagram can be represented in figure 3-4.

Figure 3: Sea H2O chilling system for the survey.

First, saltwater demands to be filter to forestall sand or other substance come ining the system that can do harm to the system equipment. To duplicate the protection against any unwanted substance come ining the system, strainer will be put after the screen. Pump is used to impart the sea H2O from the sea into capacitor and go around it back to sea. Note that cheque valve is installed in the system to forestall contrary flow in the system. In the capacitor, heat from the steam will be rejected to sea H2O which is low temperature compared to the steam. During the heat rejection procedure, the latent heat of the steam will be released and therefore it transform into liquid.

Determine Optimal Working Region for Condenser

Condensation occur when the temperature of chilling H2O enters the capacitor is below impregnation temperature of the low force per unit area steam enters the capacitor. Lowering the capacitor force per unit area will impact the turbine whereby the work done in turbine will be addition. Cooling H2O must be go arounding into capacitor to cut down the capacitor temperature which will besides cut down it force per unit area. For this survey sea H2O is the chilling medium to be used in the works. Reducing condenser force per unit area needs excess flow rate of the sea H2O. Therefore, to take downing capacitor force per unit area, sea H2O flow rate must be increased. As more sea H2O enters condenser, more heat will be rejected in the capacitor therefore increase the energy generated by turbine. This can be shown in figure 3-5 below where the energy generated by turbine is additions as the flow rates increase. A survey has been done to see the effects of take downing capacitor force per unit area based on Simple Rankine Cycle ( fig 3-6 ) . The force per unit area is reduced from 1 Bar to 0.1 Bar.

Figure 3: Consequence of cut downing capacitor force per unit area on the turbine.

Figure 3: Consequence of cut downing capacitor force per unit area on overall efficiency

As province before, flow rate of sea H2O demand to be increased in order to cut down the capacitor force per unit area. This has increase the energy usage by pump in the chilling system. This can be illustrated in figure 3-7 below where the energy use for pump is increased as flow rate of the sea H2O addition. To associate all of the statement above, it can be merely said that by cut downing capacitor force per unit area, the thermic efficiency of works is increasing and besides does the energy usage to pump the sea H2O.

Figure 3: Consequence of cut downing capacitor force per unit area on sea H2O chilling pump.

Lowering capacitor force per unit area can increase works thermic efficiency, but it besides can cut down overall efficiency of the works. Therefore, optimum on the job force per unit area for condenser demand to be determines. The optimum on the job force per unit area can be determined by ciphering the different between net energy generate by turbine, and net energy usage by chilling pump, ( ) . The differences between net work done in turbine and net work done by pump can be plotted in the in graph as shown in figure 3-7.

Figure 3: Optimum working part

From figure above, it can be se that by increasing flow rate, capacitor force per unit area lessening and turbine power, Wt and energy usage for go arounding pump, Wp addition by I”Wt and I”Wp. The different between I”Wt and I”Wp is can be used to find the optimum on the job force per unit area for capacitor. The corresponding different increased until it reaches maximal point degree Celsius and lessening until zero in the graph which mean that the energy usage to pump sea H2O is equal to energy generate by turbine. The maximal point degree Celsius is the optimum value for sea H2O flow rate, and capacitor force per unit area, .

Using X-steam Table for Parameters Calculation

There are a batch of parametric quantities to be determines in this undertaking such as heat content ( H ) , entropy ( s ) , force per unit area ( P ) , and temperature ( T ) . All of the parametric quantities can be determine by utilizing steam tabular array which is take clip. Therefore, to cut down clip consume for obtaining the parametric quantities, X-Steam excel spreadsheet with IAPWS IF97 Steam Tables macro embedded inside the spreadsheet will be used in this undertaking. X-Steam is a Microsoft excels spreadsheet which contains IAPWS IF97 Steam Tables macro in it ( see fig 3-8 ) . Each parametric quantity in this undertaking can be obtained by insert a specific bid or merely by insert known value. For an illustration, the bid to obtain impregnation temperature for 5 Bar of force per unit area is ( Tsat_5 ) .

Figure 3: Ten Steam excels spreadsheet.

Chapter 4

Analysis

Introduction

This subdivision discuss about the effects of modifying Simple Rankine Cycle to Reheat Rankine Cycle and Regenerative Rankine Cycle. The efficiency of these 3 rhythms is discussed in farther. By theory, it is known that Regenerative Rankine Cycle is the most efficient among these 3 rhythms and most used in existent power works. Thus, a simple theoretical account of Regenerative Rankine Cycle consists of 4 feed-water warmers are used in order to find the optimal operating status for capacitor. In order to accomplish the aims, the analysis was divided into several analysis which is, to analyze the effects of take downing capacitor force per unit area on capacitor temperature, thermic efficiency, turbine power end product, flow rate of chilling H2O, and pump power required. After all relationship determined, optimum working government for capacitor can be determined by happening the highest point on the secret plan of the difference between net alteration in turbine power and net alteration in chilling H2O flow rate.

Simple Rankine Cycle

Simple Rankine Cycle consist 4 major constituents which is pump, boiler, turbine, and capacitor. This rhythm operates at lower force per unit area of 0.2 Bar and the highest force per unit area is 167 Bar as shown in the tabular array below.

Figure 4: Simple rankine rhythm operates at force per unit area of 0.2 saloon to 167 saloon

Table 4: Parameters for simple ideal Rankine.

Equipment

Pressure, P ( saloon )

Temperature, T ( A°C )

Enthalpy, H ( kJ/kg )

Entropy, s

( kJ/kg.K )

Specific volume, V

( m3/kg )

Quality, ten

Pump

0.2

60.05864

251.3997

0.831952463

0.00101714

A

Boiler

167

60.75584

268.3657

0.831952463

0.00101018

A

Turbine

167

538

3398.617

6.415128821

0.01989398

A

Capacitor

0.2

60.05864

2111.764

6.415128821

6.03544744

0.78911

First, pump start pumping H2O signifier 0.2 Bar to boiler force per unit area ( 167 Bar ) which is the maximal force per unit area in the rhythm. In boiler, heat added into the H2O and alteration it phase to steam which so enter the turbine. The energy of the steam causes turbine and generator which both attach at the same shaft to revolve and therefore generate electricity. It leaves the turbine at 0.2 Bar and enter capacitor at quality of 0.76. Heat is rejected at changeless force per unit area and the liquid-vapor mixture wholly condenser going liquid at the issue of capacitor.

Pump, boiler, turbine and capacitor is a steady-flow device, therefore all of the device can be analyzed as a steady-flow procedure. Normally the alteration in possible and kinetic energy of a steam is little and neglected in this analysis. The steady-flow energy equation per unit mass of steam for the rhythm ;

Equation 4.1

Conservation of energy for each device can be expressed as follows ;

For pump, ( q=0 )

Equation 4.2

For boiler, ( w=0 )

Equation 4.3

For turbine, ( q=0 )

Equation 4.4

For compressor, ( q=0 )

Equation 4.5

The thermic efficiency for simple ideal Rankine rhythm is ;

Equation 4.6

Where,

Equation 4.7

Increasing Rankine Cycle Thermal Efficiency

Thermal efficiency for Rankine rhythm can be increase by assorted methods such as by superheat the steam force per unit area to high temperature, take downing capacitor force per unit area, and increasing the boiler force per unit area. However altering the parametric quantities of the rhythm will impact other constituents as good. In order to guarantee all constituents can run good, some alterations on Rankine rhythm can be made.

Ideal Reheat Rankine Cycle

Increasing boiler force per unit area could increase thermic efficiency, but it besides increased wet content that enters turbine. This can do turbine blade to gnaw. To get the better of this job, steam can be expanded in two phase turbine and reheat it in between. This rhythm is called Reheat Rankine, where the alteration was to add reheat procedure in simple ideal Rankine rhythm.

Figure 4: Reheat Rankine rhythm.

Table 4: Parameters for reheat Rankine rhythm.

Equipment

Pressure, P ( saloon )

Temperature, T ( A°C )

Enthalpy, H ( kJ/kg )

Entropy, s ( kJ/kg.K )

Specific volume, V ( m3/kg )

Quality, ten

Pump

0.2

60.06

251.400

0.832

0.001

A

Boiler

167

A

268.366

0.832

A

A

HP turbine

167

538.00

3398.617

6.415

A

A

Reheat

42

A

3003.218

6.415

A

1.000

LP turbine

42

538.00

3530.799

7.177

A

A

Capacitor

0.2

A

2365.727

7.177

A

0.897

Figure shows T-s diagram on a reheat Rankine rhythm operates at low force per unit area 0.2 saloon and high force per unit area of 167 saloon. It is a alteration from simple ideal Rankine rhythm where enlargement procedure takes topographic point in two phases which are hard-hitting turbine and low-stage force per unit area turbine. First steam expanded isentropically in the high-pressure turbine. Then it was sent back to boiler and reheated to inlet temperature of first phase turbine recess at changeless force per unit area of 42 saloon.

Energy analysis for reheat Rankine rhythm are same with simple ideal Rankine. The lone difference is the entire heat input and the entire turbine work end product. The entire heat and entire turbine work end product can be expressed as follows ;

Equation 4.7

Equation 4.8

Regenerative Rankine Cycle with 4 Feed-water Heater

Another alteration that can be made to increase thermic efficiency of simple ideal Rankine rhythm is to increase temperature of H2O go forthing the pump. This can be achieved by pull outing or shed blooding some of the steam indoors turbine at assorted points. This rhythm is called as regenerative Rankine rhythm.

Figure 4: Reheat regenerative Rankine rhythm with 4 feed-water warmer.

Table 4: Parameters for regenerative Rankine rhythm.

State

Pressure, P ( saloon )

Temperature, T ( A°C )

Enthalpy, H ( kJ/kg )

Entropy, s ( kJ/kg.K )

Specific volume, V ( m3/kg )

Quality, ten

1

0.2

60.06316

251.3997

0.83195246

0.001017144

A

2

2.04

A

251.5869

A

A

A

3

2.04

A

507.3506

A

0.001061089

A

4

167

A

524.8543

A

A

A

5

167

150.0927

642.8147

A

A

A

6

167

204.3186

877.9828

A

A

A

7

167

253.2438

1101.538

A

A

A

8

167

538

3398.617

6.41512882

A

A

9

42

A

3003.218

6.41512882

A

1

10

17

A

2802.614

6.41512882

A

1

11

4.77

A

2567.713

6.41512882

A

0.91564

12

2.04

A

2429.34

6.41512882

A

0.8737112

13

0.2

60.05864

2111.764

6.41512882

A

0.78911

14

4.77

150.0927

632.5554

1.84266776

A

A

15

2.04

A

627.8353

1.84266776

A

A

16

17

204.3186

871.8879

2.37146137

A

A

17

4.77

A

856.3515

2.37146137

A

A

18

42

253.2438

1101.628

2.82322892

A

A

19

17

A

1087.59

2.82322892

A

A

In the T-s diagram in figure, steam expanded isentropically in turbine and extracted at 4 point which is at changeless force per unit area of 42, 17, 4.77, and 0.2 saloon. Each of the steam will flux into feed-water warmer. The energy of the extracted steam is used heat H2O go forthing pump which at province 2 and 4. This cause the temperature of the H2O to increased and therefore increased the thermic efficiency of the rhythm.

In this regenerative rhythm, some sum of steam which is named as a, B, degree Celsius, and vitamin D severally will come in warmers 1, 2, 3, and 4 and the other ( 1- a-b-c-d ) will be expanded isentropically in turbine as shown in figure, therefore mass flow rate for each device is non the same. Hence, the energy analysis for turbine and capacitor will go ;

Equation 4.9

Mass flow rate for this rhythm was shown in tabular array.

Equation 4.10

Table 4: Mass fraction

mass fraction

mass flow rate

a

0.117562

32.09443423

B

0.108675

29.66831992

degree Celsiuss

0.034791

9.497909688

vitamin D

0.090088

24.59391286

Regenerative with Reheat

In this analysis, a alteration of regenerative Rankine rhythm with 4 feed-water warmers is used. T-s diagram was shown in figure.

Figure 4: Regenerative Rankine with reheat.

Table 4: Parameters for regenerative reheat.

State

Pressure, P ( saloon )

Temperature, T ( A°C )

Enthalpy, H ( kJ/kg )

Entropy, s ( kJ/kg.K )

Specific volume, V ( m3/kg )

Steam quality, ten

1

0.2

60.06316

251.3997

0.831952463

0.001017144

2

2.04

251.5869

3

2.04

507.3506

0.001061089

4

167

524.8543

5

167

150.0927

642.8147

6

167

204.3186

877.9828

7

167

253.2438

1101.538

8

167

538

3398.617

6.415128821

9

42

3003.218

6.415128821

10

42

538

3530.799

6.415128821

11

17

2802.614

6.415128821

1

12

4.77

2567.713

6.415128821

0.91564

13

2.04

2429.34

6.415128821

0.873711

14

0.2

60.05864

2111.764

6.415128821

0.78911

15

4.77

150.0927

632.5554

1.842894975

16

2.04

627.9248

1.842894975

17

17

204.3186

871.8879

2.371498789

18

4.77

856.3674

2.371498789

19

42

253.2438

1101.628

2.823010218

20

17

1087.486

2.823010218

In figure, reheat takes topographic point at force per unit area of 42 saloon. Steam enter the boiler and a kg sum of steam extracted into warmer and ( 1-a ) kilogram was heated in boiler to 538A°C which is inlet temperature of turbine. The thermic efficiency for this rhythm is 56.30 % which is the highest thermic efficiency among others rhythm in this analysis.

Lowering Condenser Pressure on Simple, Reheat, and Regenerative Rankine Cycle

Analysis has been done to obtain the effects of take downing capacitor force per unit area on simple ideal, reheat, regenerative, and regenerative with reheat. The consequence was shown below.

Figure 4: Consequence of take downing capacitor force per unit area on assorted Rankine rhythm

Figure 4-5 shows the consequence of take downing capacitor force per unit area on 4 Rankine rhythm which are, simple, reheat, regenerative, and regenerative with reheat. All corresponding rhythm thermic efficiency increased when operating at lower capacitor force per unit area. This shows that cut downing condenser force per unit area can increase thermic efficiency. In this analysis, regenerative Rankine with reheat has the highest thermic efficiency which is 56.8 % when capacitor force per unit area operates at 0.1 saloon. Simple, reheat, and regenerative have thermic efficiency of 41.25 % , 43.08 % , and 46.48 % severally when operates at force per unit area of 0.1 saloon.

Effectss of Lowering Condenser force per unit area

Analysis has been carried out to find the effects of take downing capacitor force per unit area on thermic efficiency, heat transportation rate, turbine power end product, required sea H2O flow rate, and required sea H2O pump power. Regenerative Rankine with 4 feed-water warmers with reheat is used as a theoretical account in this analysis in order to find the optimum working government for capacitor. This is because most of bing power works are utilizing this rhythm.

Table 4: Maximal force per unit area can be lower.

Pressure, P

Temperature, T ( A°C )

T, ( K )

T-318K

0.200

60.06

333.06

15.06

0.190

58.95

331.95

13.95

0.180

57.80

330.80

12.80

0.170

56.59

329.59

11.59

0.160

55.31

328.31

10.31

0.150

53.97

326.97

8.97

0.140

52.55

325.55

7.55

0.130

51.04

324.04

6.04

0.120

49.42

322.42

4.42

0.110

47.68

320.68

2.68

0.100

45.81

318.81

0.81

0.090

43.76

316.76

-1.24

The capacitor force per unit area is 0.2 saloon and will be reduced to 0.1 saloon as can be seen in figure. This is the maximal force per unit area that can be lower due to the fact that condensation procedure merely occurs when temperature of chilling H2O is below temperature of steam come ining capacitor. The difference must be 10 K to 15 K. Knowing that the temperature of sea-water at capacitor recess is 30A°C so, the maximal capacitor temperature that can be lowered is 45A°C.

Effectss on Thermal Efficiency

From analysis that has been carried it is found that take downing condenser force per unit area will increase thermic efficiency of power works.

Figure 4: Effectss of take downing capacitor force per unit area on thermic efficiency.

When capacitor force per unit area at 0.2 saloon the efficiency is 55.11 % and increased to 55.62 % at 0.1 saloon ( refer to calculate 4-6 ) . The Thermal efficiency has increased due to the of turbine work end product that besides increase when the capacitor force per unit area is lowered. The heat input is besides addition but the increase is significantly little comparison to work end product in turbine. Thus the thermic efficiency for rhythm has addition. The addition in turbine work at province 13-14 can be shown in table 4-7 where the sum of heat content at capacitor recess is diminishing when capacitor force per unit area is lowered.

Table 4: Addition in heat content at capacitor recess.

Condenser Pressure, Pc ( saloon )

Condenser Temperature, Tc ( A°C )

Enthalpy out, hout ( kJ/kg )

Enthalpy in, hin ( kJ/kg )

0.200

60.06

251.3997

2111.7547

0.190

58.95

246.7790

2105.5790

0.180

57.80

241.9468

2099.1034

0.170

56.59

236.8805

2092.2954

0.160

55.31

231.5537

2085.1165

0.150

53.97

225.9351

2077.5212

0.140

52.55

219.9872

2069.4547

0.130

51.04

213.6644

2060.8505

0.120

49.42

206.9107

2051.6268

0.110

47.68

199.6564

2041.6808

0.100

45.81

191.8123

2030.8813

Effectss on Turbine Work Output

Lowering capacitor force per unit area can increase turbine work. This can be illustrated in figure 4-7. The shaded country is the alteration in turbine when take downing the capacitor force per unit area. Lowering capacitor force per unit area will do steam measure of wet that come ining turbine addition. This can do turbine blade to gnaw when high force per unit area steam with wet work stoppage turbine blade. To rectify with this state of affairs, steam can be heated up to a higher temperature or reheat more than one.

Figure 4: Increased in turbine work end product.

Figure 4: Effectss of take downing capacitor force per unit area on turbine power end product.

Effectss on Condenser Heat Transfer Rate

Heat transportation rate is a motion of heat at one topographic point to another. The unit is defined as Watt ( W ) or ( J/s ) . Heat transportation occurs when there are two different temperature of medium. The expression for heat transportation rate is given as ;

Equation 4.10

In this analysis, heat transportation occurs at heat money changer which is at boiler and capacitor. In boiler heat is added up into the system and in capacitor heat is removed from capacitor, therefore turning steam into liquid. Lowering condenser force per unit area can diminish capacitor heat transportation rate. This is due to the difference between capacitor and sea H2O temperature has decrease. Figure 4-9 shows the effects of take downing capacitor force per unit area on heat transportation rate.

Figure 4: Effectss of take downing capacitor force per unit area on capacitor heat transportation rate.

Effectss on Sea Water Flow Rate

Sea H2O is used as a chilling medium to take heat from capacitor. Sea H2O measured in Malaysia ‘s sea is about 30A°C. The sum flow rate required to take heat from capacitor can be calculated by utilizing following equation ;

( 4-11 )

Where:

= condenser heat transportation rate, ( kilowatt )

= chilling H2O flow rate, ( kg/s )

= H2O specific heat, ( kJ/kg.K )

A= heat transportation surface, ( M2 )

K= heat transportation coefficient, ( kW/m2K )

tc= distilling temperature, ( A°C )

tw= chilling H2O recess temperature, ( A°C )

( 4-12 )

Where ;

I’=fouling factor, ( 0.8 )

I?w=cooling H2O denseness, ( kg/m3 )

Z= no. of base on ballss

In this analysis, sea H2O belongingss such as denseness and specific heat was taken at standard salt which is 35 g/L. Density and specific heat capacity at temperature of 30A°C obtained from International Towing Tank Conference ITCC [ citation ] was 1021.77 kg/m3 and 3.99 kJ/kg severally. Calculation was done in Matlab by using Newton Raphson Method to obtained sea H2O flow rate.

Figure 4: Sea H2O flow rate required to take down capacitor force per unit area.

As in figure 4-10, when heat transportation rate, QI‡ lessening, sea H2O flow rate required is increase. From old analysis, cognizing that heat transportation rate is decrease when take downing capacitor force per unit area. Hence, lower capacitor force per unit area ; sea H2O flow rate must be increased. Sea H2O flow can be increase by modifying chilling system parametric quantities such as pump power or caput required.

Effectss on Required Pump Power

Pump is used in chilling system to reassign sea H2O from sea into capacitor and discharge back to sea. Pump power can be determined from following equation ;

( 4-13 )

Where ;

WI‡p= Pump power, ( kilowatt )

g= gravitative acceleration, ( m/s2 )

VI‡= sea H2O flow rate, ( m3/s )

I·p= pump efficiency

I·m= motor efficiency

H= pump caput, ( m )

Head is defined as the difference in tallness between 2 points measured from fixed data point.