Design and Thermal Analysis of a Supercritical CFB Boiler

Transcription

1 eissn: 2487X Desig ad Thermal Aalysis of a Supercritical CFB Boiler JUKURI.RAMAKRISHNA DEPARTMENT OF MECHANICAL NEWTONS INSTITUTE OF SCIENCE & TECHNOLOGY ABSTRACT A boiler is a closed vessel i which water or other fluid is heated. The fluid does ot ecessarily boil. The heated or vaporized fluid eits the boiler for use i various processes or heatig applicatios, icludig cetral heatig, boilerbased power geeratio, cookig, ad saitatio. Supercritical Circulatig Fluidized Bed (CFB) boiler becomes a importat developmet tred for coalfired power plat ad thermalhydraulic aalysis is a key factor for the desig ad operatio of water wall. I this thesis, a simple boiler ad a CFB boiler are compared for the better heat trasfer performace. The D modelig of simple boiler ad CFB boiler is doe i Pro/Egieer ad Heat trasfer aalysis is doe i Asys. The material used for boiler is steel. I this thesis, it is to be replaced with copper ad brass. Thermal aalysis is doe to verify the better heat trasfer rate by comparig simple ad CFB boilers ad better material. Ad eve CFD aalysis is doe for verifyig the heat trasfer i the CFB boiler. INTRODUCTION SUPERCRITICAL BOILER A supercritical boiler is a type of steam geerator that operates at supercritical pressure, frequetly used i the productio of electric power. I cotrast to a subcritical boiler, a supercritical steam geerator operates at pressures above the critical pressure,200 psi or 22 MPa i which bubbles ca form. Istead, liquid water immediately becomes steam. Water passes below the critical poit as it does work i a high pressure turbie ad eters the geerator's codeser, resultig i slightly less fuel use ad therefore less greehouse gas productio. Techically, the term "boiler" should ot be used for a supercritical pressure steam geerator as o "boilig" actually occurs i the device. Workig of a Supercritical Boiler A supercritical boiler burs pulverized coal ad is a ocethrough boiler, meaig that it does t require a drum to separate steam from water. Rather tha Mr.T.LOKNATH ASSISTANT PROFESSOR DEPARTMENT OF MECHANICAL NEWTONS INSTITUTE OF SCIENCE & TECHNOLOGY boilig water to produce steam ad the usig that steam to tur a plat s turbie, a supercritical boiler operates at such high pressure (,208 psi/221.2 bar or above) that the fluid matri i it ceases to be liquid or gas. Istead, it becomes what is kow as a supercritical fluid. This supercritical fluid turs the turbie that geerates electricity. As it does so, it drops below the critical pressure poit ad becomes a mi of steam ad water, passig ito a codeser. I the process, less fuel is cosumed tha i a traditioal drum boiler, makig supercritical boilers more efficiet tha their subcritical couterparts. Beefits of Supercritical Boilers It s hard to believe, but supercritical boiler techology is almost 100 years old. Grated, it did t look aythig like what it does today whe Mark Beso first obtaied a patet to covert water ito steam at high pressure levels i 122, but the drive to improve the power idustry s ability to bur coal through supercritical meas has bee costat throughout the history of moder boiler egieerig. After some problems i the 10s ad 170s, supercritical techology bega to hit its stride i the 180s ad has bee yieldig better performace statistics ever sice. With icreasig govermet ad idustry pressures to reduce emissios ad icrease efficiecy, supercritical boilers (or steam geerators, sice o actual boilig occurs i supercritical uits) promise to be a part of the overall solutio by usig less fuel ad helpig coalburig plats comply with more ad more striget emissios regulatios. Supercritical boilers offer beefits i the three iterrelated areas that mea the most to plat owers ad operators today: efficiecy, emissios, ad cost. While supercritical boilers cost more tha comparably sized subcritical boilers, the larger iitial capital ivestmet ca be offset by the lifecycle savigs yielded by the techology s improved efficiecy, reduced emissios, ad lower operatig costs all due to its higher steam temperature ad pressure parameters. DESIGN OF BASIC BOILER Available olie: P a g e 48

2 eissn: 2487X CFB BOILER DESIGN BASIC MODEL OF BOILER MADE OF BRASS Available olie: P a g e 480

3 eissn: 2487X BASIC MODEL OF BOILER MADE OF COPPER Available olie: P a g e 481

4 eissn: 2487X CFB MODEL OF BOILER MADE WITH BRASS Available olie: P a g e 482

5 eissn: 2487X CFB MODEL OF BOILER MADE WITH COPPER Available olie: P a g e 48

6 eissn: 2487X TABLES Available olie: P a g e 484

7 eissn: 2487X THERMAL ANALYSIS TABLES REGULA temperatu thermal directioal R re flu flu () MODEL mi ma mi ma ma mi brass copper CFB BOIL ER brass copper temperat ure mi m a thermal flu mi e e directioal flu () Thermal error mi 1.2 e e 12 ma mi ma mi. 4E E 1.21 E 1. 2E 1.8 E E cfd aalysis report of SIMPLE BOILER ma Thermal error.1 2E E 10 ma trasfer rate by comparig simple ad CFB boilers ad better material. As per the aalysis doe if we observe the results obtaied for the simple boiler, we ca fid that the brass material is the best material for the simple boiler as the flu obtaied is lees compared with the copper. As i the other case a CFB boiler is cosidered ad aalysis is doe, as if we compare the results of the CFB boiler we ca see that the brass material CFB boiler is much better for the better life output as the stress is very miimum i this material. Her eve CFD aalysis is doe to the CFB boiler to verify the stress ad pressure ad desity values, As if we compare both the results we ca coclude that CFB boiler gives much better output for the material ad eve the temperature ad the flu obtaied is the best results for the boiler. AUTHORS 1. STUDENT mi ma 2. GUIDE 1 sheer stress 0 8.8E+00 velocity magitude E+01 temperature 2.E E+0 static pressure 1.7E E+04 desity Cfd aalysis report of CFB BOILER 1.2E+00 mi ma sheer stress E+00 velocity magitude E+01 temperature 4.4E E+02 static pressure.4e E+02 desity 1.2E+00 CONCLUSION I this thesis, a simple boiler ad a CFB boiler are compared for the better heat trasfer performace. The D modelig of simple boiler ad CFB boiler is doe i Pro/Egieer ad Heat trasfer aalysis is doe i Asys. The material used for boiler is steel. I this thesis, it is to be replaced with copper ad brass. Thermal aalysis is doe to verify the better heat Available olie: P a g e 48