Flow Measurement of Dense Slurries Using the Sonic Doppler Principle

Abstract

are demonstrated. A simple zero c r o s s i n g c o u n t e r t o determine a n a v e r a g e frequency of t h e n o i s e spectrum y i e l d s flow rate w i t h a s t a t i s t i c a l e r r o r E where, F, i s t h e count rate and, T, t h e i n t e g r a t i o n t i m e . s two t r a n s d u c e r s are used, one r a d i a t e s s o n i c energy i n t o t h e s l u r r y . w h i c h s c a t t e r s i t t o b e rec e i v e d by t h e second t r a n s d u c e r . I n s o n i c d o p p l e r blood flowmeters p u l s e d t e c h n i q u e s a r e o f t e n used. These may have m e r i t a l s o f o r p i p e flow p r o f i l i n g , b u t are o u t s i d e t h e scope of t h i s paper.I n t h e p r e s e n t i n v e s t i g a t i o n t r a n s d u c e r s were coupled t o t h e p i p e w i t h l u c i t e wedges t o g e n e r a t e s h e a r waves i n t h e p i p e by mode conversion. F i g u r e 1 T h i s g e n e r a t o r showed s i d e bands a t l i n e frequency i n t e r v a l s of about 60 dB below t h e main s i g n a l . Without c r y s t a l s t a b l i z a t i o n t h e s i d e bands masked t h e broad band flow s i g n a l . The two curves. shown i n F i g . l , r e p r e s e n t measured a t t h e same p o i n t . t h e s i g n a l through a 0 . 1 Hz l o w p a s s f i l t e r ; o t h e rwise t h e s i g n a l i s about 1 0 dB wide a s can b e s e e n when t h e s p e c t r a are p l o t t e d on a n o s c i l l o g r a p h s c r e e n . t h e flow and no flow c o n d i t i o n s The n o i s e spectrum w a s o b t a i n e d by p a s s i n g D i f f e r e n c e S p e c t r a O s c i l l a t o r s t a b i l i t y requirements could be r e l a x e d by u s i n g a "tuned" d e t e c t o r . I n Fig. 2 t h e r e c e i v i n g t r a n s d u c e r o u t p u t i s connected, v i a a 40 dB g a i n a m p l i f i e r t o t h e RF t e r m i n a l s of t h e balanced modulator. A 0.5V s i g n a l from t h e t r a n s -S p e c t r a m i t t e r d r i v e r i s connected t o t h e LO t e r m i n a l s of A p r e l i m i n a r y s p e c t r a l a n a l y s i s f o r low veloc i t y c o n d i t i o n s showed t h e r e c e i v e d s i g n a l t o have a bandwidth of several hundred Hertz, Fig. 1. The s i g n a l i n t h i s c a s e w a s g e n e r a t e d by a c r y s t a l s t a b i l i z e d g e n e r a t o r . t h e modulator. The o u t p u t a t t h e I F t e r m i n a l of t h e modulator i s connected, v i a a 40 dB a m p l i f i e r , -291 c~i 3 4 4 -i / 7~/ 0~n n -0 E 9 l t 0 0 . 7 5 0 1978 I E E E

Ultrasonic Characterizations of Slurries in a Bubble Column Reactor

“…[4][5][6] The utilization of ultrasonic techniques for slurry characterizations has received considerable attention recently. [7][8][9][10][11][12][13][14] Some ultrasonic techniques are based on the principle of scattered acoustic pulses. The process is similar to sonar, in which bursts of acoustic energy are emitted into a liquid and reflections from discontinuities (solids and bubbles) are detected and measured.…”

“…Therefore, researchers have to develop their own instruments and data interpretation. The ultrasonic technique has been used widely in medical imaging, materials testing, flow detections, and level measurements. − The utilization of ultrasonic techniques for slurry characterizations has received considerable attention recently. − Some ultrasonic techniques are based on the principle of scattered acoustic pulses. The process is similar to sonar, in which bursts of acoustic energy are emitted into a liquid and reflections from discontinuities (solids and bubbles) are detected and measured.…”

Contrast medium assisted fluid flow measurements

“…These approaches can be readily applied to measuring flow of a fluid in a pipe or conduit in an industrial environment with or without modification [1], [23], [24] if suitable contrast agents can be developed.…”