Concept explainers
Spray drying is a process in which a liquid containing dissolved or suspended solids is injected into a chamber through a spray nozzle or centrifugal disk atomizer. The resulting mist is contacted with hot air, which evaporates most or all of the liquid, leaving the dried solids to fall to a conveyor belt at the bottom of the chamber.
Powdered milk is produced in a spray dryer 6 m in diameter by 6 m high. Air enters at 167°C and −40 cm H2O. The milk fed to the atomizer contains 70% water by mass, all of which evaporates. The outlet gas contains 12 mole% water and leaves the chamber at 83°C and 1 atm (absolute) at a rate of 311 m3/min.
(a) Calculate the production rate of dried milk and the volumetric ?ow rate of the inlet air. Estimate the upward velocity of air (m/s) at the bottom of the dryer.
(b) Engineers often face the challenge of what to do to a process when demand fora product increases (or decreases). Suppose in the present case production must be doubled. (i) Why is it unlikely that the ?ow rates of feed and air can simply be increased to achieve the new production rate? (ii) An obvious option is to buy another dryer like the existing one and operate the two in parallel. Give two advantages and two disadvantages of this option. (m) Still another possibility is to buy a larger dryer to replace the original unit. Give two advantages and two disadvantages of doing so. Estimate the approximate dimensions of the larger unit.
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- ⑤ b Δε m ab C 40arrow_forwardProblem 10.16 An isosceles triangle of base 40 mm and altitude 54 mm has its base in the V.P. The surface of the plane is inclined at 50° to the V.P. and perpendicular to the H.P. Draw its projections. Construction Refer to Fig. 10.17. An isosceles triangle has its base in the V.P., so con- sider that initially the triangle ABC is placed in the V.P. with base AB perpendicular to the H.P. 1. First stage Draw a triangle a'b'c' keeping a'b' perpendicular to xy to represent the front view. Project the corners to xy and obtain ac as the top view. 2. Second stage Reproduce the top view of first stage keeping ab on xy and ac inclined at 50° to xy. Obtain new points a', b' and c' in the front view by joining the points of intersection of the vertical projectors from a, b and c of the second stage with the corresponding horizontal locus lines from a', b' and c' of the first stage. Join a'b'c' to represent the final front view. Here, the front view is an equilateral triangle of side 40 mm. X 54…arrow_forward%9..+ ۱:۱۹ X خطأ عذرا ، الرقم الذي أدخلته خاطئ. يرجى إدخال رقم بطاقة الشحن الصالحة والمحاولة مرة أخرى. رصيد هاتفك قم بمسح الرمز = رقم بطاقة التعبئة 7794839909080 رمز مكون من 13 او 14 رقماً طريقة إعادة التعبئة قم باعادة تعبئة الرصيد إعادة تعبئة الإنترنت إعادة تعبئة الرصيد O >arrow_forward
- Problem 10.14 A hexagonal plane of side 30 mm has a corner in the V.P. The surface of the plane is inclined at 45° to the V.P. and perpendicular to the H.P. Draw its projections. Assume that the diagonal through the corner in the V.P. is parallel to the H.P. d' a 2 b b.f C' c.e b 'C' H.P. (a) V.P E HEX 30 e' O' d' a a' b' C' b' X y a b,f c,e d b,f (b) c,earrow_forwardProblem 10.18 A 60° set-square has the shortest edge of 40 mm lying in the V.P. The surface is in- clined to the V.P. and perpendicular to the H.P. such that the front view appears as an isosceles triangle. Draw the projections of the set-square and determine its inclination with the V.P. Construction Refer to Fig. 10.18. A 60° set-square inclined to the V.P. and per- pendicular to the H.P. can appear as an isosceles triangle in the front view, when the shorter edge is in the V.P. 1. First stage Draw a right angled triangle 40 a' a' b' c' b' X 40 C' a,b C a,b a'b'c' keeping 40 mm long a'b' perpen- dicular to xy. Project the corners to xy and obtain ac as the top view. 2. Second stage Draw another right angled triangle a'b'c' on the horizontal locus line from points a', b' and c' of the first stage such that length of b'c' is equal to that of a'b'. Project a'b' to meet xy at ab. Draw an arc with centre a and radius equal to ac of the first stage to meet the vertical projector of c' at…arrow_forward□ 40 a' 12 o' a O d'arrow_forwardTL = 85 D. Problem 9.12 The top view of a line measures 60 mm. The line is parallel to the V.P. and inclined at 45° to the H.P. One end of the line is 25 mm in front of the V.P. and lies on the H.P. Draw its projections and determine the true length. Interpretation Let the line be PQ parallel to the V.P. The front view has true length and the top view is parallel to xy. Construction Refer to Fig. 9.12. 1. Draw a reference line xy. Mark point p' on xy and point p 25 mm below xy. 2. Draw a 60 mm long line pq parallel to xy. This repre- sents the top view. 3. Draw line from point p', inclined at 45° to xy to meet the projector from point q at point q'. Join p'a' to represent the front view. Measure length of p'a' as true length of line PQ. Here T.L. = 85 mm. Result True length of line PQ is p'q' = 85 mm. 5 Fig. 9.12 p 60 σarrow_forwardProblem 9.13 A 70 mm long line PQ does not have H.T. and V.T. One end of the line is 30 mm in front of the V.P. and 20 mm above the H.P. Draw its projections. Interpretation As the line PQ does not have H.T. and V.T., it is parallel to both H.P. and V.P. Construction Refer to Fig. 9.13. 1. Draw a reference line xy. Mark point p' 20 mm above xy and point p 30 mm below xy. 2. Draw a 70 mm long line p'a' parallel to xy to repre- sent the front view. X 20 p Fig. 9.13 3. Also, draw a 70 mm long line pq parallel to xy to represent the top view. 70 q yarrow_forwardProblem 10.19 A square lamina ABCD of side 40 mm is suspended from a point O such that its surface is inclined at 30° to the V.P. The point O lies on the side AB 12 mm away from A. Draw its projections. Construction Refer to Fig. 10.19. 1. First stage Draw a square a'b'c'd keeping a'd' parallel to xy. Mark a point o' on a'ď at a distance 12 mm from end a' as the point of suspension. Also, mark the centre of the square g' to represent the centre of gravity. 2. Second stage Reproduce the front view of first stage such that o'g' is perpendicular to xy. Project corners and obtain bd as the top view. 3. Third stage Reproduce the top view keeping bd inclined at 30° to xy. Obtain new points a', b', c' and ď' in the front view by joining the points of intersection of the vertical projectors drawn from points a, b, c and d of the third stage with the corresponding horizontal locus lines drawn from points a', b', c' and ď of the second stage. Join new a'b'c'd to represent the final front view.arrow_forwardProblem 10.15 A circular plane of diameter 50 mm is resting on a point of the circumference on the V.P. The plane is inclined at 30° to the V.P. and the centre is 35 mm above the H.P. Draw its projections.arrow_forwardYou are asked to manufacture 10 kg of polyester with a number-average molecular weight of 1000 by polymerizing butane-1,4-diol(HO(CH2)4OH) with adipic acid (HOOC-(CH2)4-COOH).a) What weight of diol and diacid do you need, respectively? To whatextent, p, should the reaction be carried out to? Assume a stoichiometricbalance.b) What are the number and weight fractions of dimer, trimer and tetramerat this point in the reaction?c) Because of the polymerization by dehydration to olefin, 3 mol% of thediol will be lost. What would be the number-average molecular weightwhen the reaction is carried out to the same extent? How could you offsetthis loss so that the desired molecular weightarrow_forward9.4. A PID temperature controller is at steady state with an output pressure of 9 psig. The set point and process temperature are initially the same. At time = 0, the set point is increased at the rate of 0.5°F/min. The motion of the set point is in the direction of lower temperatures. If the current settings are PART 3 LINEAR CLOSED-LOOP SYSTEMS Ke = 2 psig/°F Ti = 1.25 min TD = 0.4 min plot the output pressure versus time.arrow_forwardarrow_back_iosSEE MORE QUESTIONSarrow_forward_ios
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