Variable capacitance differential pressure transducer The variable capacitance differential pressure transducer is a very popular device which is used to sense and transmit pressure differences. Figure 114.2 shows a schematic of such a device. A pressure signal is © scanned with OKEN Scannercoup 11 Dyramc Behave! Second cdr Systems 209 transferred through an isolating diaphragm and fill liquid in a taney system with difleenia pressure sensing semen (rigoe aria) attached atthe other end ofthe capillary (Figure 118.20). Here ihe pressure is transmitted through a second isolating diaphragm and fil Aguid Gilicone oil), to a sensing diaphragm. A reference pressure Mil balance the sensing diaphragm on the other side ofthis diaphragm. ‘The position of the sensing diaphragm is detected by capacitor plates on both sides of the diaphragm. A change in pressure ps of a processing nit (€8. @ change in the pressure of a vessel, or a change in the liquid Jove n'a tank, etc.) will make the pressure p change atthe end of the capillary tube. ’A farce balance around the capillary will yield force due to the force due to the pressure p, of the process pressure p2 exercised exercised attheend1 —] ~ at the end 2 of the of the capillary capillary = (mass) x (acceleration) or pid = pd (Me) (as) a) where A = cross-sectional area of the capillary ‘LZ length of the capillary tube ‘pz density of the liquid in the capillary tbe {fThuia displacement in the capillary tube = displacement of diaphragm “The force pa at the end of the capillary is balanced by two forces: /- resistance exerted by mae ( tre iaphragm | +( whic acts like a spring/ viscous ction fore) MALO Mreeised by he nia) AN? ax = kero at where K = Hooke's constant for the diaphragm CZ dsnping coefficient of the viscous liquid in front of the siaphragm Substitute psd ine. (1A) by itseaua given bY caution (114.10) and dbp) dx Ca, x aA py quaay Kg.) dt? K dt x? y © scanned with OKEN Scannery 9 ponder sma 2 y indicates thatthe response Of the devicy 1A.) clearly a follows second-order dynamicg He, Ite define t= ALP/Ke., 26r 0 it) on ( the diaphragm displaces, pangs oes ESSE Pi TK, nd A= UK, we take the transfer function , 3 fs 6) Poe ers + 1 Pneumatic valve ‘The pacumatic valve isthe most commonly used final contol ele. ‘ent. Is system that ex is inherent second-order dynamics, Consider a typical pneumatic valve like that of Figure I1A.3, The poston ofthe sem (or, equivalently, ofthe plug atthe end ofthe stem) willdetermine the sizeof the opening of the flow (flow rate). The position ‘lance of all forces acting on it. These forces are: ‘4 =Torce exerted by the compressed air at the top of the dia Pree: 2 ag af the signal that opens or closes the valve and 4 is the area of force acts el the diaphragm; this force act fore exerted iaphragm; the displacemer ky by the sprin 8 attached to the stem and the is the Hooke's mt; i acts uy constant for the spring and x is ipward, © scanned with OKEN Scanneryap 11 Drmame Behawor ol Second-Order Sytems ° " au 4 frictional force exerted uy dt contact of the stem wit coefficient between ste ‘ward and resulting from the close h valve packing; C is the friction m and packing, Apply Newton’s law and take pPA~Kx-~c% (4 de Vg, ow M)@x Cde (i) aKa ** Let = M/Kge, 26t = C/K, and K, = A/K and take @x 5, de BOE aE xe Kp The last equation indicates that the stem: posi second-order dynamics. The transfer function is (s)_ AK PO) (MjKegs*+ ¢s +1 1n_x follows inherent (a.12) Usually, M << Kg, and as a result, the dynamics of a pneumatic valve ‘an be approximated by that of first-order system. © scanned with OKEN ScannerChapter 19 Industrial Bioprocesse; 10.1 INTRODUCTION Teds Bioprocess engineeting ia special branch of chemical engineering, It isthe conglomersed trathematcs, biology and industrial proces. Ideals with design and development of processes fore tranufacaring of product from biological materials. For example - pharmaceutical product. aby ds wih tdying of various biotechnological process used in industries fr large sale producicn 10.2 BASIC CONCEPT OF BIOCHEMICAL PROCESS ‘The basic concept of biochemical process involves following important terms = 10.2.1 Cell Icis che tin unc off tha can replicate independently. Therefore cell is also called building bloke! lie. The study of ellis known as cel biology. It consists ofa protoplasm enclosed within a membast wich, coor ucla and proxi - 10.2.2 Bacteria {cies living thing that has only one cl. Under the microscope it look ike a ball sod or spi presen in mos ofthe ol, water aceic hots i i a is > spring and radioactive waste material. The 0 ‘bacteria is known a bcerialogy All bacteria ae not harmful, Some bacteria helps vo digs fresh body ned viains. iso sed to make hay fond suchas yopur ed cheese. BU reco and alae arf ht ean oe inet ‘The large seaweed roe rganism that ranges from microscopic size tol sow Cee ne 2 Ie 2m nao non ar pan ey. Ne wept SE ‘Containing brackish, seasnd waste ant LOSSES for biochemical waste treatment. Outdon! Pe water are god for growingalga, becauseit needed vast sutfiee © scanned with OKEN Scannerpoprgess08 gy soph. They ean not manufacture their own food themselves. They decompose dead matter se se are parasices. et ie os Yeast 1 oscar microorganiam sounded by cll wall hough some species ar mull Fer itince nutes, With ver few exrptions,yeasteproducs by proces known as budding. jan. Viruses retell in structure, It is mainly composed of nuke acid and surrounded by protein feat ly comps a prot These fthe virus aries ate below the alton of light microscope. Virus exist ony at Fc highy hospi parasite. Crain mould and many bacteria ae subjected wo invasion by sew particles. {03 BIOREACTOR Akoeacor isa device that support biologically active environment to catied out chemical process sich involves organisms. Generally, fermenter are called bioreactor. Some example of bioreactors are jah menter, horizontal fermenter, tower fermenter, ae lie fermenter. A typical bioreactor is shown ig 1. sam (Aor mo sit} (2) godin er cet egigee ange Aeypesvate (6) (@) Sight lass ean of ine (2) Mannate wih gh ass (10) Agar sha oun net (42) | (1) Pad bre team eteg ter cute (13) —» =f ate oF (18 Coaing cots (7) Mae +20 Sample vane Sou 9) ' { (Seng nt at entng water inet (16) ——+ +: ou ro. 101 Borsa Soran ae common ena ee! consting agar, al coling ci a va) eK coi pager qefencions dented st litains dese in igang contacting elf mises olin soning of far contl, misng tnd heat ane The fam conta i ached citer by wae a © scanned with OKEN Scanner182 "netrumentaon ane, mechanical destruction or by chemical intr foam agents. Several other factors such Hey pressure, shaft power and viscosity are monitored. m ‘Whena pacar opis introduc into a seected growth mati, ga the particular organism, The growth of the inoculum does not take place inp tea, proces. The adaptation take place during this period and called lag phase. Fallon sxe of gow ofthe onanism incteses exponentially for a cen pen "Te rs ynential Pres Sime of exponential has thera of growth of th sin desig bec ofthe eon hat the concentration ofthe nutrients decreases whereas theo sessbsancsineeases continuously. During this petiod, the rat of groth afore, ‘Tas pevod iced deceleration phase. Afer the deceleration phase the growth of oso, and the culture enters a stationary phase, Themis used fr biochemical process grow ina selected medium which spss ‘quired by che organism. There are varity of media exists, but a medi contains a areas Seoee soucs wae sland micro natin ate most preferable, For example ie poo> ‘ins the gape ised as medium forthe growth of organism, 10.4 STIRRED TANK HEATER Astredtanheaterisa device that used to 2 oplindrical vessel consisting agit temperate convolleranda eee Fig, 10.2, ‘Stemperatu heat theliqud in atankby an clcicha ater, sensor and are made of sinless te converter. A typical industrial tiered unk bo ‘now. @ Scanned with OKEN Scannerests nicer: klommeltoe toa ecm fda iin ‘The automatic control for stirred tank heater can be achieved by measuring the outlet fluid ‘using a temperature sensor and. i Me tf a vance oon esa ea ett be rng 95 ON-LINE DATA ANALYSIS pele danas fr state and parameter imation for biochemical proce ia technique which etd improved cone performance with cahanced roductvig, or example consider 4 Soe The deficiency of online information of bioreactor concerning the process sae impose sermon or effective contol action. Hence, for bester monitoring and contra of bioreactor online Teron ofthe process variable i essential ‘The different methods by which stare and parameters ofa bioreactor can be estimated are as hares: (Kalman iter (i) Observer Gi) Balanced equation (9) Neural neework (0) Fussy easoning (6) Other methods Inthis section, Kalman filter method is discussed. 105.1 Kalman Fileer The Kaman fei sed to provide mos favourable eximate of measured and unmeasured sa BF ean ee faa by combininginfrmaton using matiemata ods of he reas A eck dag of rate estimation scheme by Kalman fiers shown in i103 Process Measurerent tsimaton cual ‘got Emad state | ra parameter Process monsuroments mot Kaan th. Fig. 10.3 Bock dag by Kalman filer a any sine i “munlB Process estimate obtained Sleeps ie ex consasof wo recursive steps In the Hes SP the process Thal , il ; ert aed nthe Kalan fie cos ep te propagted mols eae i Moi Propagate the initial state estimate ee ed wi the procs menuement © Pov 2 Pa can alu del with stochastic Primate of the Process so 1 ecan provide accurate P isadvantages: Ie require much ti he optimum estimate condition jme and effort © scanned with OKEN Scanner