B. A. R. C.-668

sGOVERNMENT OF INDIA

ATOMIC ENERGY COMMISSION

STUDIES ON APPLICATION OP AIRLIFT INFUEL REPROCESSING ENGINEERING

byA. N. Fnsad, G. R. Bilaiubramanian and K. Raoganatban

Fuel Reproceuing Division

BHABHA ATOMIC RESEARCH CENTRE

BOMBAY, INDIA

1977

B.A .R . 0 . - 6 6 8

GOVERHMEHT OP IHDIAATCMIO ENERGY COMMISSIOU

STODIES ON APHilOATIOU OF A U t l i M I FFUEL HEIE0CES3IH0 ENGINEERING

by

A.N. Erased, O.R. Balaeubramanlan ana K. RanganathftnFuel Reprocessing Division

BHABHA ATOMIC RESEARCH CENTREBOMBAY, INDIA

1977

INIS Subject Category : E15: E13

Descriptors

FUEL REPROCESSING PLANTS

FLUIDS

RADIOACTIVE MATERIALS

MATERIALS HANDLING

TRANSPORT

PLUTONIUM COMPOUNDS

SOLUTIONS

AIR

ENTRAINMENT

FLUID FLOW

FLOW RATE

MEASURING METHODS

STUDIES OH APH.KUIIOT QP AIHIiIBT IHFUEL HEHtOCE3SD)G ENGINEERINB

by

A.N. Brasad, G.R. Balasubramaniarl* and Kg Hanganathan

1. mXHCDUOTION

];ran primitive days a i r l i f t la being used BB a mode of

transport c£ llquidB, i s view of tiie abaenae of moving partB and

eimplioi ty of the system i The baelo prinoiple that whan a i r i s

bubbled in one ce* the l e g s , the column of l iquid a ir mixture, r i ses

to balance the liquid l e v e l in the other U leg and thereby provides' a

l i f t , 1B being u t i l i s e d . When handling radioactive f l u i d s , the problems

aesoolated due t o the frequent fa i lure of the moving parks I n the caea

of diaphragm arid centrifugal types of pumps, make one explore the poss i -

bility of utilising air l i f t for transport of these radioactive liquids.

The air l i f t system oan alao be employed for metering the fluids by

metering the prime air used,. provided a suitable relationship between

tho two ooold be arrived rat. totoe present series of experiments were

conducted to study the above possibility.

2. 3XHSR3MEOTAL SET UP OF DIRECT METERINO SYSTEM

The general arrangement of the set up 1B eh own tn F i g . ( i ) .

From the available height consideration, the maximum possible .column

of a i r l i f t was only 12M. To study various column heights of air l i f t ,

the pipe chosen waa f l ex ib le polyvinyl ohlorlde pipe of 18 mm inside

d i a . Three types of differences were studied. The or i f i ce used was of

6 mm dia of the shape shown i n Mg.( -1) . It was found that there was

hardly ^ - 3% variation i n l iquid r a t e . The a i r far the l i f t WBB supplied

* Pow i n R.R.O., nelpakkem, Tamil.Nadu

- 2 -

through a pressure regulating valve and was metered through a rotamater.

The air l i f t column venta to a vent pot mounted on pulley to facilitate

location at different graded heighta. The pressure In 'she vent pot was

measured through a manometer* A level probe was Inserted ID the vent pot

for purpose to be discussed later , the liquid from vent pot Is drained

te ths col lset i i^ syetea. The discharge from vant pot was of open discharge

type to avoid pressure variation likely lo ariae from variation of height

of the pot of colleotion. The fluid tried waa water. The feed to the air

l i f t waa from oonetant level source, which 1B another overflow pot fed

either by another auxiliary all l i f t t pumping from the tank from ground or

by a tank located above. Tho experiments were so planned that there waa

no joint In the air l i f t column. Experiments were carried out varying the

column height from 3M to 12M and submergence Was maintained at 30$, 40$

and 5C# at each column height. The liquid rate for particular air rate

was measured for each case. Air rates were increased t i l l entrainment

could be observed. The s?rta of curves Indicating liquid rate v/s air

rate at room pressure and temperature for eaoh submergence of each oolumn

are plotted (Tigs. 7-13), The air pressure used was just enough to

balance the hydraulic head and provide the flow. The flew of air i s

oharactarised as foi l owe i At Ion flow rate there is formation of small

bubbles and at a particular atage there begins a formation of bubbles

Ilka a piston - the piston size increases at higher rate and the rate of

Blip also increases. At higher ratea there i s almost, continuous column

of air , the liquid foaming a film on the aides. The piston type of flow

provides the maximum efficiency. Ae the bubble size increases ( the s l ip

increases and inefflclenoy seta in . It can be observed from the curves

that there la a well defined region of linearity and a region of plateau

- 3 -

which meane only about BO - 40$ of the total range i s available, for

metering purpose. The plateau region forms almost 40 - 5U$ as the eff ici-

enoy of the l i f t varies for different oolumn heights. However far u

particular set up, the readings feme very well reproducible. This indi-

oatoa the possibility rtf metering in the l inearity region, with accurate

measuring device, in the range raided. However, each system needs ca l i -

bration arid is true as long as the orifice size ie not altered either by

sal t imposition or dir t accumulation.

3. EFFICIEHCY OP AIR LIM

If one assumes is^iobeipial conditions in the a i r l i f t column,

an approximate relation can be developed by equating the work done to

l i f t the liquid through the l i f t height, to the work done by the isother-

mally expanding s i r ironi submergence pressure to vent pressure.

i . e . Whe -4 IB Va Ing (Ps/Fa)or HT1 log (Ps/Pa)

Where W = fft rate of liquid

he = iht of l i f t

Ps = vent pressure + submergence pr.

Va = Volume of a i r used at Pa at room tern. 20"C

Pa = atmospheric or vent pressure

If V i s actual wtg liquid pumped then

E = W he

Pa Va log (Ps/Pa)

The efficiency for each system is plotted in Pigs.(7-13)

It is seen that the efficiency varies erratioally with different column

heights. These equations are however approximate, especially for these

diameters of system. The surface of the pipe, surface tension and

- 4 -

viaooai ty of l iquid i Te loc i ty of a i r m t e r mixture which decide tha

bubble farming ebaraoterlBtioa aaem t o ocntrol s o r e . However, the

theore t i ca l axpaotatlon of i increase in l iquid rate f a r increase In

aubmargenoe la followed, pue t o area of looat lon no other aqueous

l iquids oould be tried* With kerosene and 556 TBP i t waa found that

thd frothing la s l i g h t l y more and In WO tuba due t o i t a wetting

c h a r a c t e r i s t i c s , l iquid e l i p a more.

4 . HBTBHIHO THE LIQUID BY VARYING THE SUBMERGENCE

Because of the wide range of. plateau one oan see If one could

vary tha aubmerganoa, the plateau region w i l l oonat i tute a metering

system* Pur t h i s , for a particular system of 12 M column height, tha

submergence waa varied by laaana of varying the vacuum in the vent pot ,

maintained by ua a i r j e t . The s e t up i s shown i n F i g . ( 2 ) . The vent

pot drain log waa oonnected t o l iqu id leg in a overflow pot, to f a c i l i t a t e

maintaining the necessary vaouum - the seal l eg l ength had t o be equivalent

t o the submergence to be created by a ir j e t . An addit ional height ia

provided for the free draining from vent pot to overflow pot. The exper i -

ments ware oonduoted t<pe a ''2 V. column with maximum vacuum of 25 mm of

Hg and the l iquid rate for d i f ferent a ir ratee found out. The curves in

Pig.14 Table IV prove tha aanumirtioiii eince one aeea wal l defined plateaus

f o r eaoh aubmergenoe af ter a i r xate around 20 1/min. The vacuum waa varied

from 150 an t o 250 mm of mercury. Mile matho* a l s o , whenever height

perm'lta, can be used far materin;; uiclng the plateau region whera f o r

var ia t ion of a ir rate upto 30 t o 4054:, the l iquid rate varies by 45*.

5 . KBTBSIW BY MBASDSIRO THB IB1JB1 1S.THB VERT PM

Bxparlasnta were oaxiiAd out t o sttiSy the poaalbi l l ty of ualng

tha l iqu id l e v e l in the vent pat tie an indicat ion of tiie l iquid flow

- 5 -

rate* Tho vent poet WRB provided with a remote pneumatic liquid leve l

indioator aa well ee vioiinl l eve l measurement, i t was observed that

thex* wao not appreciable l e v e l build up in the vent pot as the liquid

flow r a t e s were increased; ihe variat ion of the l e v e l due t o airpuiBation

i t e e l f woe of the order of 25 - 40 mm. She maximum l e v e l change that

oould ba observed was about 100 - 125 mm for the whole range. A reduction

of the a l so of the vent pot t o 50 mm did not resul t in any improvement.

Ttom the consideration of venting a ir and entrainment the 50 mm size was

to umall.

6 . MEZTEBtHO BIT OONTHOLLrNO THE LIQUID HEAD ABOVE AH CR IF ICE

The dependence of the l iquid flow rate on the s i ze of the d i s -

charge o r i f i c e and the hitight of the l iquid column above i t i e well known.

This could be u t i l i s e d as a means of measuring the l iquid flow rate .

Experiments were carried out with a 1.6 meter and 75 mm dia pipe provided

with a l e v e l measurement. Orifice plates of di f ferent s i z e s could be

eorewed at the bottom of the pipe. The following o r i f i c e s i ze s were

used 1.5 mm, 3mm, 5.35mm and 6mm. The pipe was f i l l e d with water and the

flow rate wae measured at dif ferent l iquid l eve l s in the pipe. The

l iquid flow rates were plotted against the l iquid head in a log-log

sheet (F ig . 15 Table I I ) . Ffccm the curves i t can be seen that the olopa

of the s tra ight l ine ia 0 . 5 . The or i f ice coef f ic ient could be determined

by the intercept and was found t o vary between 0.67 - 0 . 8 . After these)

preliminary t r i a l s , a scheme as Bhown in S?ig.(3) was worked out to

u t i l i s e the a ir l i f t for maintaining the constont l iqu id l eve l in the1

pipe. A aimilar system has been reported for the oontrol of interfnce

* K. Srinivaean, et al "Pilot Slant StudieB in a Pulsed SolventExtraction Column" - BAEC 589 - 1973.

- 6 -

In a puleed solvent extract ion column using a lx l i f t for the aqueous

discharge from the column. The 75 dm dia l iqu id column was fed by means

of the a i r l i f t and the rate of flow of a i r was controlled by a d i a -

phragm control valve whose operation was governed by the l e v e l in the

75 mm dia pipe. The control ve lve used was a f lu ted trim type. Two

s i z e s of orlf loe - 3mm & 1.5111111 were used in these experiments. The

performance was s a t i s f a c t o r y . The l eve l could be controlled w e l l ( the

flow rate variat ion waa within acceptable l i m i t s and the roprducibi l l ty

good. The r e s u l t s are shown i n Table I I I -

7 . HETBRIBQ BY OOTTROUiINO THB. LIQUID DISCHARGE BY MEANS OFCOTTHOL VAIVE

Another mode of metering tried u t i l i s e s the prinoiple that

when ths head i s constant f o r a particular o r i f i c e s i z e , the flow i s

constant . The scheme i s shown i n P ig .4 . In "the submergence var ia t ion

system t r i e d , the overflow pot was provided with drain connected t o a

diaphragm control v a l v e . The height of loca t ion of diaphragm valve i s

suoh that the head avai lable does not drain the l iquid fas ter than the

feed from vent pot. Overflow was always maintained. The diaphragm

control valve air pressure was changed from 3 - 1 2 ps ig . The l iquid

rate at particular jprosuure se t t ing waa measured. It was found that

the r a t e variation wae w i th in 3$ for a f i x e d s e t t i n g . However, -the

l inear re la t ion with a i r pressure and l iquid ra te could not be obtained

as t h e diaphragm 'oontrol valve i t s e l f did not have proportional character -

i s t i c s , as ver i f ied by feeding water from di f ferent constant l e v e l t a n k s .

i s chore was no other1 diaphragm Control valve a v a i l a b l e , the proportion-

a l i t y a l iquid rate {to diaphragm oontrol valve a i r pressure could not

- 7 -

be confirmed. Beoauee far a particular liquid flaw diaphragm control

valve pressure i s fixed - *he l i f e of diaphragm control valve i s very

high.

8 . APHiICillOIT OF AIR LIFT FOR ERAHSFER OP CONCENTRATED PLUTONIUMSOLUTION

Since for hlghi concentration plutonii'-n l iquid transfers

effected by ateam je t t.yetem, th.i movement of l iquid have t o be either

by gravity of a i r l i f t , involving no moving parts . Experiments were

carried out t o study the problems of transfer of highly concentrated

Plutonium so lu t ions in the process c e l l s of the proposed Reprocessing

Development Laboratory at HalpaUkam, Madras. The tanks in these c e l l s

w i l l be of safe geometry and a maximum height of 2 meters. The c e l l

height i s 5.5 metres. Gravity flow from one tank t o the other i s not

possible due t o the height l imi ta t ions of the c e l l s . In most cases the

transfers are t o be effected between tanks in the same l e v e l s .

By adopting the a ir l i f t system u t i l i s i n g the available suli-

mergenee, only about 4f# of the tank could be emptied in a period of

about 30 minutes. By supplimenting the submergency leg by a vacuum of

600 mm of water r almost a l l the contents of the tank could be transferred,

the hold up being about 150 - 200 ml i n the submergence l o o p . The

arrangements are shown in Fig . (5 ) . The maximum vacuum that c ould be

applied t o booot the submergence i s limited from the consideration of

head for flow from vent pot t o the receiving system and a reasonable

height of a t l e a s t 1.5 meters from the vent pot no -no a ir j e t or any

vacuum system which w i l l be located on the top of the c e l l s .

P i g . ( 6 ) shows the proposed layout in the process c e l l s of the

Reprocessing Development Laboratory.

- 8 -

Entrainment $ liqulfi by air wi l l be a serious problem when

handling concentrated Plutonium solutions. To minimise the degree of

entrainment, the vent pot was provided with a perforated plate and the

air was made to impinge on I t . The air insuing from this pot was made

to pass through another similar pot with a perforated plate. The

liquid collected could drain back to the tank. The degree of entrain-

ment was determined in the following way. 1.5M sodium nitrate solution

was used to simulate the concentrated plutonium solut ion. The sodium

nitrate solution was reoiroulated in the tank i t s e l f using the air l i f t

system for one hour. The air issuing out of t"he vent pots was made to

paos through a known quantity of water in a wash b o t t l e . (150 ml -

measured after stopping the air l i f t ) . This was mixed well and analysed

at the end of the experiment. It was found that the concentration a?

sodium nitrate in the wash bott le was 1.5 ppm. The entrainment for one

hour works out to be 0.0017 ml of the parent l iqu id . Extrapolating this

to a case of the most active dioeolver solution having an activity of

4 ourieB/ml, the eattainment in One hour works out t o be 6.8 a i l l i o u r i e s .

The entrainment oan be further reduced by providing a f i l t e r before the

air Jet or vacuum system. It may be nsoessary to isolate tho system and

provide a shielding if needed and maintain periodic wash down of the

Unas with steam or dilute acid to avoid build up of act ivity . The

entrainment calculations are shown in Appendix *..

9 . GENERAL EffiCAUTIONS

Far better performance the air l i f t column must be as straight

as possible and -the weld joints must be minimised as there Is likelyhood

of breaking of the bubbles. The vent pot can be vented to feed tank

i t s e l f and the tank provided with sufficiently bigger vent.

- 9 -

10. 00NCHJSI0N

These experiments have proved that air l i f t i s a valuable

tool far a reprocessing engineer, It can be used for metering directly

or a part of a metering system. It can be adopted for handling highly

radioactive solutions and the entrainment oan be sufficiently reduced

by introducing suitable de-entrainera. The most important advantage

is the absence of any moving parts and i t s wider flow rate ranges.

It oan a1 J be used successfully to transfer completely solutions

between tanks at the same leve l .

ACKNOTIEDGEM3HE

The authors wish t o thank Shr l B.G. t e l e , Shr i S.H. Tadphale

end Late S h r i B . I . Uimavane f o r carry ing out the experimental work.

Table - I

iffi L&I HHFtElUSCE MS DWBCT WSOUMi

l iquid imta 1 (lph)

ef Ult5 In f l • 19 III an T| x 3) lm T« = 40

j TJWOTB- ! Actual jBffloleiwj- i Theanij t lo i l ; j { Mart I

• Thoore-; tgtaal i>."'lelenc»; 1]isor»; «etual{ Errielenqt th*or<4• t i e d ' ' • tleal i i * tleal '4 1 1 1 ' • h

detail

Ibtd.h.Itfrt

SS'

SO'

U>

10"

«

CD

80

SO

«

90

90

«

3D

S3

«

90

•a

<aso

SB

«

90

I11.S1S4.S

HS.C

MS

1W.0

1U.0

17S.S

XS9.S

17S.S

—

as. a18U0

122.0

S71.S189.00

M2.0

S8.8

862

uc133

80

110

n i l

93

90

—

84

—

SB

ato

90_

7.00aa.oo37.BS

88

78.00

48.09

M l

55.70

M.S0

—

S1.70

M.10

—

is.a10.80

18.00

turn_

22S

sa4ST

490

SSB

498

S4T

s i ?

5S1

SIS

SSB

381

944

S4S

22*

S7T

nassr

BS161

» •

sss

2 U

IBS

198

154

84

180

112

40

114

110

es

140

64

40

88.0049.O3

44.8>

5164.00

43.00

43.00

43. »

W.80

4A.B

K8.B0

54.00

90.70

w.«S1.00

29.10

JT.90

34. ID

16.00

•A.IO

44«

658

974

980

rtt448

990

894

1054

70S62S

1093

754

438

1088

758

44B

1154

79«

814

184

240

8.18

SB)

1.78

ass

sre230

isa

179

192

110

ITS

154

104

1E8

IS)

78

SE.8

S8.4

M . 4

31.5

S8.8

28.S

20.3

a.o

2S.B

SSJB

2S.2

VJ0

28.80

22.4

1B.2

« . 4

22.8

U . 9

18.4

14.8

EE9985

148

870

704

872

1485

1041

1E71

10SS

989

1500

1086

7S2

van1134

77?

Wai

1953

T*«

IBS274

S68

284

905

*<4

SSB

2S0

90S

250

188

S28

191

£99

190

160

102

i°a

1 3

78

27.827.8

SB.7

».e4S.2

31.6

24.0

19.3

94.8

17.8

a.st/.i1S.4

11.1

U . I

15.2

« . «

1S.0

!S.2

8921558

B48

two15H

898

IB80

1S88

SDS8

1404

1X52

2120

t « 8

978

2172

1S1E

898

2KB

1S44

S 8

!92279

370

1U

SID

213

S29

250

299

282

188

350

US

114

ISO

1 »

94

194

?JD

88

21.720.8

19

nil

23.0

24.4

18.7

ia.o

14.S

18.7

13.4

lfl.5

1S.2

11.8

8.7

10.8

20.5

9.S

7.1£

8.4

Table - I I

VJRIJfEIQN OP LIQUID RATE FOR DIFFERENT ORIFICESIZES AT VARIOUS LIQUID HEADS

trrct «ff liquid

l«SO48oc?U>«c

198

lac

{ S • •

iA

•e.o89.7S7.878.0ne» aM * 8

304.4117.0139.P

]" 1.8 M 1" 1•1/aln 1Aim.

1M l.t918 S.S

3B» t

870 4

410 1

4110 1

4W (

830 1

G40

U«t.41.0

1.8

1.0

1.18

r.o

flaw rate takm whaa l«r«l van aanntnt In p«* byt«vol roiowod 2a ii

Taole - I I I

METERING BY MEANS OP THE LIQUID DISCHARGETHROUGH AN CHIFICE SIZE - 3 ram

. 1 -

Sat laval '

Callbrnt-Ian*

15

3ft

3ft

30

38

40

48

BO

85

W

65

TO

r Aotunl laral

In onatrmorifice

% eall

14

19

24

80

34

39

43

48.00

54

59

84

00

BB.2B

34.03

40.48

4T.30

93.70

90,00

ae.io72.0070.1084.5001.7008.10

How rata j Aetnal flow rate apheall- mmTT

tad at different ptftioda1 1 9 f 3

brationgraphtph.

54.460.660.071.075.878.083.067.908.005.008.0

102,0

54.0•3.007.2«0.O74.478,081.088.801.204.800.0

102,0

55.303.407.071.073.278.080.780.0ftl.805,000,9

103.0

54.802.0ae.o71.074.078.181.080.101.104.0

101.0loa.o

MBi h»<nl r*£«rr«d i* lavaft prpbt which ic 19.5 • • above arifleatorraapenda 1ST tm» trim lavol praba.

Ttt'ula

METEBIKe SHE LIQUID BY VARYIHG THE BUBMEIlUEWCE

Faroentaga of

Air THU inl i i r t i pusUinnt*

Vattr r»4« In Htfei pti*

10

12.5

15

17,a

20

22.0

48,5

82

77

S8

82.9

49

G4.5

61

80

96

toe

113

118

77

98

19S

126

1?.»

1SS

tSP

07

117*5

190

151

159

IOC

189

19S.B

104

173

181.5

183.0

FIG.-1 EXPERIMENTAL SET UP FOR STUDY OF USE OF AIR Lit- T FOR DIRECT

METERING

VENT I LEVELPROSE

HEIGHT OFLIFT

COLLECTINGPONT TOCHECK THELUUDRATE

18mm ID.VC.AB

LIFT COLUMN

100mm SQUARE VENT POT,,WITH ADJUSTABLE

MOUNTING HEIGHT

VENT I

ROTAWTER

AUXILLARY AIR LFT FORCONSTANT SUBMERGENCE WATER FEED

TANK-2

OVERFLOW

\

-A-DRAIN

I/4"SCHIOPIPE

DTYPES OF DFFUSERS TRIED

FIG.-2 USE OF AIR LIFT FOR METERING BY VARYING SUBMERGENCE BY VARYING

VACUUM W VENT POT

VACUUM .VAC. HV<L-HO I

100mm SIDEVARIABLE HEIGHTVENT POT

PROBE FOR PRESSUREMEASUREMENT

RO1AMETERPRESSUREGAUGE

(7\ RRV

NEEDLE J~INALVE u

H L - 1-eiGHTOF LIFT

H V - BOOSTED SUBMERGENCE

HD- HEAD FOR D R A W *

MATER FEED TANK.

COLLECTING PONTFOR CHECKINGUXJDRATE

AR FOR IAUXILLARY %*AIR LIFT T

FK5r3 USE OF AIR LFT IMDIRECTLY FOR METERING BY FEEDING TO A CONSTANTLEVEL POT

OVER FLOW

8Cms.DIATUBE

REMOVABLE vORIFICE PLATENj

1

Cm*

. TRANSMITTER . —

VENT 1 ••

r

i NLEVEL PROBE,IOjrCitM

YlLIQUID COLLECTION aRATE CHECK POINT

laomm SIDEVENT POT

l8mm.DIA.aH:EED AIRLIFT

RECORDERCONTROLLER

i

PRESSUREGAUGE

/•>

J , J , 1 J . COMPRESSEDDIAPHRAGM^ NEEDLE 1Tf AIR SUPPLYCONTROL VALVEWLVE

WATER FEEDTANK

enunAIRLFT TlORIFICE J

FIG.-4 USING AIR UFT INDIRECTLY FOR METERING WITH THE HtLP OF ADIAPHRAGM CONTROL VALVE

VENT

CONSTANT,HEAD POT

-JL

JD.C.V.

FOR A FIXEDAPPLIED APPLIEDPRESSURE OND.C.V. ORIFICEOPENING ISCONSTANT.HENCERATE IS CONSTANT

PRESSURE PROBEVACUUM 600mm IOF H20 NJ .1

FIG-5 SIMULATED SET UP FOR STUDY OF TRANSFER OF CONCENTRATED PLUTONRJMSOLUTION

AIR FOIRARJET

VEiHTPOT

PERFORATEDPLATES -

780mm.

•8

AIRUFT

PRESSURE PROBEVACUUM APPLIEDfiOOltMn-af HgO

3M.

TSmmdkiTANK.

[OVERFLOW

arcm.

ZSOCffJ

1_ I 480mm

KNOWN AMOUNT OFABSORBENT THROUGHWHICH AIR IS mSSEO

FIG.-6 PROPOSED AIR LIFT TRANSFER SYSTEM FOR CONCEN >

SOLUTION IN A PROCESS CELL

U> RUTONIUM

ro AIR JET

Mil*

\ ; -

1 • -

, A

• ' a'

0

iaa

CELLsiror •

VfSLL

. " • *

i

- • .CELL ROOi : CONCRETE WALL' \ - • '> >v.

+ 5.5M.

FEED SYSTEM TOMIXER SETTLER

V\

INTER T A N K ^TRANSFERS

., • -

* . . • • • • » • •

VENT P O T ^

I JAM

—

1

1||11||

i

JJ

5

AIR TO AIR LIFT

V

1+2.IM.

EVER SAFEDIA. TANK

-O.IM0.0 CELL FLOOR

COVERED AIR LIFTSUBMERGENCE PITS(POISONED OR EVERSAFE)

1 /

. AIR RATE Ipnt-

io is teo

AIR RATE Ipm.-

AR RATE Ipm.-

110 20

AIR HATE Ipm.—

10 20

AIR RATE Ipm.-

t±m- %ki

% EFFICIENCY

AIR RATE Ipm.-

AIR RATE Ipm-

log

n

i1ij

FWrli POT CAUBRATIW

- ^

pHEM) IN

CURVE JS*^

nCm. •

no

Appendix - X

Bntrainnent studies

Concentration of NaNO, in 150 ml of solutionthrough whioh the exh&uat air has been passedfor 1 hour

Molarity of the solution ' '

Holes carried

Volume of 1.5 M NaNO- carried

Rate of entraimnent

Assuming water absorption efficiencyonly 5 $

Normally a tranafer takes 7 mlnuteB tobe completed

• *. . Entralnnent/tranBfer

Assuming the dase of dlesulver solutionof aotivity 4 o/al. (total activity)

Activity entrained/transfer

Since about 252 litres of std air isused/transfer - activity level of air

1.5 ppn

1.77 x 1

1.77 x 1

.0015

1.7 x 10~5 ml

ml

1.7 x 10"5

3.4 x 10~3

3.4x16~\ m l .100 of

liquia

1.688 mill! curies

6.3 uc/litre of air

Appendix - II

.0 IKPIUEHCE OF lastli HEIGHT <B COIOMN

One ia Interested to know how the total height of airl ift

oolunm influenoea the discharge rate.

Considering isothermal aonditiona and applying equation (1)

for the weight rate of flow: W

Whe - M l o g ( B * ; ^ " * - ) „

- M log ( h ah ^ t o ) x e

e • efficiency factor

ha • atmoppherio pressure in ft of water

ha • submergence pressure in ft of water

ha - height of l i f t In f t . of water

If H la total height of oolumn and S Is submergence, factor

oan be putt

W-H- 0 - s ] = e . RE log( h a ^ H X 3 )

One finds from the equation tf there are two l i f t s , working

on the same liquid, satre submergence and effioienoy for a given air

rats , the discharge 1B more far an airl i ft of shorter length. For.

example, theoretical ratio of liquid rates for different height of

columns, for 50$ submergence conditions are 0.86, 0.895, 0.95 for

T»0 W40 ff40 where V 40 indicates weight rate of dischargeW10 , W20 , W30

far 40' oolumn air l i f t .

From the experimental figures we find that these are not

followed as the effioienoy factor not only vary for air l i f t s of

different heights, but also for different air rates.

The efficiency of a l i f t la Influenced by llquld/alr ratio

and average velooity of mixture through the tube. The recommended

velocity given in literature are for 1/2" and 1" nominal bora pipea

In the table. It la found in our experiments that efficient lifta

have liquid/air ratio kg/litre around 0.54 - 0.44 and velocity of air

liquid fixture 0.42 - 0.80n/aec. depending on submergence head. Table

gives the liquid/air ratio and mixture velooity at maximum discharge

oonditions.

Influence of density of liquid

The equation (1) oan be written an

«he - e -HP leg ("* ^ B g )

- e RT log (1 + H )

- a HI log (1 +fj£ )

he • height of l i f t

% » atmoepherlo presaure

VB m submergence praaaura

he • submergence head

9 - density of liquid

The weight rate of liquid discharge ia more for l i f t

operating on heavier liquid, If a l l the other conditions are aame.

"Recommended design parametere, for 1/2" and 1" dla nominal

bora plpeai

£ eubmargence Liquid/air kg/l i ter

35 0.174

50 0.352

65 0.615

Rtnonaended maximum baok flow velocity 1.5 m/seo.

•Reactor Hani Book Vol. II - Fuel Reprocessing.Kurbohenlo Technical Report - 27.