Class 3 Happy Mnday! Terminlgy Densities, MW, mle and, flw rates, and temperatures Pressure stuff next class Cnvert mass fractin t mle fractin Using a basis usiness Fr thse wh added the class late the inf materials are n my web page Please help me get t knw yu! I may end up writing a letter f recmmendatin fr yu smetime See pdf file Errr in 4 th Editin (early printing) Tday: Terminlgy, using a basis Next time: Pressure, manmeters Then: Mass and mle balances Then: Thermdynamics, vapr pressure, humidity, energy, heat capacities Then: Energy balances Specific Gravity (SG). Terminlgy Handut 1. Find a friend and g ver the sheet 2. Write r remember questins Definitin: Density/Reference Density Typical Reference Density = water at 4 C Value: 1 g/cm 3, kg/m 3 r 62.43 lb m /ft 3 SG given at particular temperature (des nt have t be the reference temperature) T get density frm SG: ( SG)( H, ) 2O ref SG H 2O, ref 1
Practice n SG 1. Lk up the SG f Tluene in the back f yur bk (Table.1).866 Is this fr a gas r a liquid? What is the density in lb m /ft 3?.866 62.4 lb m /ft 3 What des the (2/4) in the clumn heading mean? (see page 44) 2. Lk up the SG f water in Table.1 Nte the superscript (als n sulfuric acid) Mle and Mass Fractins y x Must knw what these represent physically! Must be able t interchange between the tw Nmenclature differences: Web and bk Web uses x i fr mle fractin, w i fr mass fractin Remember: Nt all the mle (r mass) fractins are independent. If yu have n then n-1 f the mle fractins are independent. Why????? Please specify which type f mles!!! Yu have seen MW expressed in g/ml What abut kg/kg-ml? ls lb m /lb-ml MW carbn = 12 g/ml = 12 lb m /lb-ml = 12 kg/kg-ml Is the cncept f lb-ml new? The bk uses ml t mean g-ml Hw d yu cnvert frm g-ml t lb-ml? 1 lb-ml = 454 g-ml (just like 454 grams in a lb m ) 1 lb-ml 1 g-ml Hw many g-mls are in a kg-ml? 1 kg-ml = g-ml Think-Pair-Share Cmpsitin f air is apprximately: 79% N 2, 21% O 2 Hw d yu find the mass fractin f O 2 in the air? Methd Value. Class Exercise Cnvert mle fractins t Why? Mst instruments measure mle fractins alances are dne n Mass is cnserved Mles are nt always cnserved H 2 + ½ O 2 H 2 O 1.5 mles 1 mle 1. ssume a basis CO 2.2 CH 4.5 C 2 H 6.2 H 2.1 Gas chrmatgraph t measure gas phase mle fractin (y i ) 1. 2
1. ssume a basis 1. ssume a basis CO 2.2 2 CO 2.2 2 44. CH 4.5 5 CH 4.5 5 16. C 2 H 6.2 2 C 2 H 6.2 2 3. H 2.1 1 H 2.1 1 18. Ttal 1. Ttal 1. 1. ssume a basis 1. ssume a basis CO 2.2 2 44 88 CH 4.5 5 16 8 C 2 H 6.2 2 3 6 H 2.1 1 18 18 Ttal 1. 246 CO 2.2 2 44 88.358 CH 4.5 5 16 8.325 C 2 H 6.2 2 3 6.244 H 2.1 1 18 18.73 Ttal 1. 246 1. C. verage Mlecular Weight Frmula: M y i ml ml Units: g ml ml ml g g ml ml Shuld this be mle r mass fractin? Hw D Yu Cnvert Frm Mass Fractin T Mle Fractin? asis: grams Cmpute mass Divide by MW i t get mles i Sum number f mles Cmpute mle fractin 3
Example Prblem cal gasifier prduces 5 lb m /hr f syngas, cmpsed f 35 ml% CO and 65 ml% H 2. Find: Mass flw rate f CO in lb/hr. Wrk Prblem n ard Strategies: a. Find, Get mass flw rates b. Find MW avg, Cnvert mass flw rate t ttal mlar flw rate, Get mlar flw rate, Cnvert back t mass flw rate Which Has Mre H: m 3 f liquid H 2 r a m 3 f gasline? 1. pprximate gasline as is-ctane (C 8 H 18 ) 2. Find densities & MWs Is-ctane (6 kml/m 3 at 298 K) H 2 (35 kml/m 3 at 2 K) 3. Find kmls f H per m 3 (18 ml H/ml is-ctane) (6 kml is-ctane/m 3 ) = 18 kml/m 3 (2 ml H/ml H 2 ) (35 kml/m 3 ) = 7 kml/m 3 Dry asis Given y i n a wet basis, cmpute y i n a dry basis cmpund y i CO 2.15 44 CH 4.82 16 C 2 H 6.4 3 H 2 O.125 18 ssume basis f wet gas cmpund n i y i ' CO 2 1.5 1.5/87.5 =.17 CH 4 82. 82/87.5 =.937 C 2 H 6 4. 4/87.5 =.46 H 2 O 12.5 -------- Ttal. Ttal (dry) 87.5 1. Temperature Scales Temperature C -273.15 K 273.15 373.15 Nte: we d nt use the degree symbl n the Kelvin scale! F -459.67 32 212 C K 2 15 473.15 423.15 T(K) = T( C) + 273.15 1 C (diff.)= 1 K (diff.) 5 373.15 323.15 273.15 T( F) = 1.8T( C) + 32 1 C (diff.)= 1.8 F (diff.) T( F) = 1.8T( C)+32 C F 2 4 15 3 2 5 491.67 671.67 Shuld be able t cnvert between scales!! Yu must use an abslute temperature scale when yu multiply r divide temperatures!!! R Rankine scale may be new fr yu Thermcuples prvide digital temperature values 4
Temperature Cnversins (Eqns. 3.5-1 thru 4) T(K) = T(C) + 273.15 T(R) = T(F) + 459.67 T(R) = 1.8 T(K) T(F) = 1.8 T(C) + 32 Thermcuples rtwrk: Parts f a typical thermcuple. 1) Prtective metal sheath (dark gray) made frm stainless steel r an ally (perhaps nickel and chrmium); 2) First wire made frm ne metal (red); 3) Secnd wire made frm a different metal (blue) jined t first wire t make a thermcuple; 4) Insulatin (green) made frm crushed and cmpacted mineral xide. 5) Cement t hld insulatin in place; 5) Electrical insulatin made frm rubber r plastic. rtwrk frm US Patent 4,18,624: Thermcuple structure and methd f manufacturing same by Silvi J. Rizzl, curtesy f US Patent and Trademark Office. Hmewrk Hints 3.3 Wrk bk prblem available 3.1 rchimedes principle 3.16 slurry is a ture f liquid and fine slids 3.28 Hint is given t define errr 5