Material selection consideration for reactors a) Appl Applic icab abil ilit ity y i. ii. ii. iii. iii.
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c) Avai vailab labilit lity i. ii. iii.
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$) Compromise The best material $or the constr!ction o$ the reactor is a hih alloy stainless steel. Cast iron is *not a partic!larly stron or to!h str!ct!ral material* accordin to Perry�s Chemical Engineering Handbook + pae +-+ and is not s!itable $or the conditions in the reactor beca!se the reactor operates at /01 psia and 2/1 o'. Carbon steel can not be !sed beca!se accordin to Table 3+-+ in Plant Design and Economics for Chemical Engineers 3, hydroen is not compatible 4ith carbon steel. Several other alloys s!ch as a nic5el-based nic5el-based alloy co!ld be !sed $or the materials and conditions, b!t 4o!ld not be the most economic materials. High-alloy stainless steel is the best material $or constr!ction o$ the reactor
The stainless steel Stainless stell is a lo4 carbon steel that consists o$ chromi!m at 367 or more by 4eiht. Thro!h the addition o$ this chromi!m that ma5es the stainless
steel to has a characteristic o$ corrosion resistance. There are so many type o$ stainless stell as s!ch there are abo!t 86 rades o$ it and the entire ro!o can divided into #ve classes. The stainless steel is classi#es and also can be identi#e by their o4n alloyin elemen. This also a 4ay that each di9erent type o$ stainless steel has been named. Benets of stainless steel i. Corrosion resistance
The stainless steel has resistance to4ards atmospheric and o!re 4ater environment especially in the lo4er alloy rade. t also has a hih resistance to4ards 4ide rane o$ environments and temperat!res. on any problem o$ the reactor operational environment there 4ill no presence o$ inter-ran!lar corrosion or inter-ran!lar stress.( 'ol5hard, . 30 ) ii. 'ire and heat resistance The stainless steel str!ct!re can be e%pected to behold their interrity a$ter s!ch a lon period p$ e%pos!re to the hihest temperat!re reached in hydrocarbon #res. 'or e%ample, the alvani;ed mild steel able to 4ithstand #re $or !se$!l time. http:<<444.nic5elinstit!te.or<=!rability?'ire?&esistanceandSa$ety?3662+?.pd$ iii. Hyiene t is easy to clean the stainless steel. iv. Strenth-to-4eiht advantae There is sini#cant strenthenin o$ the material $rom cold-4or5in alone and the hih strenth d!ple% rades 4hich enable the material thic5ness to be red!ced over conventional rades and hence red!cin the cost and ma5e it more cost savin. Properties of stainless steel Stainless steel can be de#ned as a $erro!s alloy. t has a minim!m o$ 367 o$ chromi!m content. As the name says, stainless steel does not stain and as mention be$ore it is resistance to4ards corrosion. t also has a remar5able resistance to r!stin or o%idation or even to any nat!ral nor man made environments.
Commercial value of stainless steel The stainless steel partic!larly has lo4 maintenance and also relatively not so e%pensive material. t is also resistance to corrosion and stainin also $amiliar l!ster that ma5es it to be an ideal based material $or host o$ commercial application. t is also someho4 an eco-$riendly material since abo!t 167 o$ ne4 stainless steel is made !p o$ re-melted scrap metal.
High Alloy Stainless Steel Hih alloy stainless steel are those stell 4hich alloy 4ere added in a lare !antities to improve the material characteristics. These materials are heat treated in order to $!rther enhance the mechanical properties and microstr!ct!re. t is carried o!t by temperin, normali;in, !enchin or sol!tionisin. This hih alloy stainless steel has a hih impact resistance as 4ell as corrosion resistance. The typical application o$ this material are: i. @!mp component - corrosion resistance ii. mpellers - corrosion resistance iii. Cr!sher a4s - impact hardenin.
Steel Steel is made !p mainly $rom an iron 4ith a carbon content o$ 6.+7 to +.37 by 4eiht. The prod!ction o$ steel are $ro, carbon and other alloyin metal s!ch as t!nsten, chromi!m, and mananese. The properties o$ the steel that is prod!ces are a9ected by the proportions and $orms in 4hich these elements are !sed. Properties of steel 3. Tensile strenth The tensile strenth 4hich means the amo!nt o$ stress that a s!bstance can ta5e be$ore it str!ct!rally de$ormed. 'or steel, the tensile strenth is comparatively hih and th!s it has a hih $ract!re resistance and brea5ae. This can be a 5ey point $or a str!ct!ral b!ildin.
+. >!ctility
The ability to chane shape 4itho!t $ract!re $or steel is !ite sini#cant. The d!ctility o$ steel enables it to be !sed in ma5in di9erent shapes and str!ct!res. /. Malleability Closely related to previo!s characteristic, steel has a ood malleability 4hich allo4s it to de$ormed !nder compression. This characteristics enable steel to be compressed into sheets o$ variable thic5ness. 2. >!rability The hardness o$ steel is hih. Bther than that it also lon lastin and has reat resistance to4ards e%ternal 4ear and tear. 1. Cond!ctivity ood cond!ctor o$ electricity and also heat. 8. &!st resistance The steel resistant to r!stin is a9ected by the addition o$ certain element. Steel has a reat $ormability and d!rability. Bther than that it also has a ood tensile and yield strentth and also a ood thermal cond!ctivity. '!rthermore, steel also has a hih resistance to4ards corrosion. References:
http://www.tatasteelconstrction.com/en/reference/teaching! resorces/architectral!teaching!resorce/history/the!history!of!iron!and!steel/the! properties!of!cast!iron!wroght!iron!and!steel
Aluminium The principal ore o$ al!mini!m is ba!%ite 4hich is prod!ced by the 4eatherin o$ the al!mini!m silicate roc5s. Al!mini!m has a characteristics o$ so$t and liht4eiht. t is also a lo4 strenth metal and can easily be cast, $ored and machined, $ormed, and 4elded. t is s!itable only in lo4 temperat!re applications. This can be e%cepted 4hen it is alloyed 4ith speci#c elements. Al!mini!m can be !sed as a deo%idi;er and also can act as a alloyin aent. 'or e%ample, tor!e converter p!mp ho!sins, aircra$t str!ct!res, electrical transmission lines are made o$ al!mini!m. Al!mini!m has a limitation that it sho!ld be !sed at a lo4 temperat!res application.
Cast iron Cast iron is an alloy o$ iron and carbon. t has ood compressive strenth b!t relatively poor tensile strenth. Deca!se o$ the imp!rities in cast iron and its crystalline str!ct!re, altho!h it is a stron material in compression, it is 4ea5 in tension and is very brittle. As a res!lt 4hen it $ailed it did so in an e%plosive manner 4ith little 4arnin. The castin process enables the prod!ction o$ comple% shapes. Deca!se it is prod!ced by castin, $or e%ample it is made by po!rin into a mo!ld, th!s it is 4ell s!ited to the prod!ction o$ intricate shapes, both str!ct!ral and decorative. 'or str!ct!ral !se, cast iron 4as best s!ited to elements 4here the predominant load ca!sed compressionE and so 4as most commonly !sed $or col!mns. t cannot be $ored. Cast iron is 4or5ed by meltin to a li!id and po!rin in molds, then by sa4in, #lin, machinin (chip ma5in methods). The sti9ness and dampenin properties o$ cast iron ma5e it an e%cellent material $or machine tool $rames and parts. Brittleness
Cast iron is very brittle. The relatively hih carbon content 4hich is 4ithin + to 1 percent 4hich means that the $ormation o$ cast iron is that it is hardens 4ith a crystalline str!ct!re that brea5s easily. t also cannot be 4ro!ht that means it cannot be beaten into di9erent $orms even tho!h 4hen heated. Tensile strength
The tensile strenth is the meas!re $or ho4 m!ch the p!llin strain 4ithin a material can 4ithstand. As $or the cast iron, the tensile strenth is lo4. Compression strength
This enerally means that the meas!re o$ the amo!nt o$ press!re that the material can ta5e be$ore it $ails. 'or cast iron, the compression strenth is hih. Th!s, this ma5e the cast iron !se$!l $or constr!ction. Corrosion Resistance
The cast iron has a very lo4 resistance to4ards corrosion. Fhen #rst man!$act!red it has a protective #lm on the s!r$ace, 4hich initially increases its resistance to corrosion. This #lm cannot be relied !pon in the lon term, ho4ever. Fhen e%posed to air and moist!re cast iron rapidly o%idi;es (reacts 4ith o%yen in the air), prod!cin the $amiliar red-bro4n iron o%ide 5no4n as
r!st. References: http://www.ehow.com/list_7622626_characteristics-cast-iron.html
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