Jawaharlal Nehru Engineering College

Transcription

1 Jawaharlal Nehru Engineering College Laboratory Manual MECHANICAL OPERATION For TE Year Chemical Engg Students 16, Dec 2003 Rev 00 biotech Engg. ISO 9000 Tech Document Author JNEC, Aurangabad

2 FOREWARD It is my great pleasure to present this laboratory manual for Third year Chemical engineering students for the subject of Mechanical Operation keeping in view the vast coverage required for visualization of concepts of Mechanical Operations in Chemical industries. As a student, many of you may be wondering with some of the questions in your mind regarding the subject and exactly what has been tried is to answer through this manual. As you may be aware that MGM has already been awarded with ISO 9000 certification and it is our endure to technically equip our students taking the advantage of the procedural aspects of ISO 9000 Certification. Faculty members are also advised that covering these aspects in initial stage itself, will greatly relieve them in future as much of the load will be taken care by the enthusiastic energies of the students once they are conceptually clear. Principal

3 LABORATORY MANNUAL CONTENTS This manual is intended for the Third year students of Chemical Engineering branch in the subject of Mechanical Operation. This manual typically contains practical/lab Sessions related Mechanical Operations in Chemical industries covering various aspects related the subject to enhanced understanding. We have made the efforts to cover various aspects of the subject covering various Mechanical operations actually used in industry will be complete in itself to make it meaningful, elaborative understandable Chemical concepts and conceptual visualization. Students are advised to go thoroughly through this manual rather than only topics mentioned in the syllabus as practical aspects are the key to understanding and conceptual visualization of theoretical aspects covered in the books. Good Luck for your Enjoyable Laboratory Sessions Prof. M. R. Gaonkar Chemical Engineering Department

4 SUBJECT INDEX 1. Sieve Analysis. 2. Ball Mill with dry material. 3. Ball Mill with wet material. 4. Ball Mill with number of ball change. 5. Jaw Crusher. 6. Double Deck Vibrating Screen. 7. Batch Settling. 8. Sigma Mixer. 9. Conduction of Viva-Voce Examinations. 10. Submission 11. Evaluation and Marking Systems

5 OBJECTIVE: T he Mechanical Operations Laboratory is equipped for the study of the various mechanical operations associated with different solids as well as fluid. Experiments mainly deal with size reduction, size separation, clarification, kneading, solid fluid separation etc. All basic experiments for particle mechanics like Jaw Crusher, Ball Mill, Hammer Mill, Sigma Mixture, Plate and Frame Filter,, Cyclone Separator,, Batch Sedimentation, Sieve Shaker are available in this laboratory. Communication skills are an important part of an engineer s career and as such we will take extra time to critique your first short, individual report. Please use those comments to improve your writing for subsequent reports

6 DOs and DON T DOs in Laboratory: 1. Do not handle any equipment before reading the instructions/instruction manuals. 2. Wear Apron before conducting experiment. 3. Handle Chemicals, equipments and glass wear carefully. 4. Strictly observe the instructions given by the teacher/lab Instructor. 5. Be careful about moving part of any equipment. 6. Clean all equipments and glassware after use. Instruction for Laboratory Teachers:: 1. Submission related to whatever lab work has been completed should be done during the next lab session. 2. The promptness of submission should be encouraged by way of marking and evaluation patterns that will benefit the sincere students.

7 WARMUP EXCERCISES: Define and discuss all the Mechanical operations that are generally used in all type of chemical industries like size reduction, size enlargement, particle separation, filtration, mixing, agitation etc. 1. Sieve Analysis: A] Aim: To find the particle size distribution of a mixture of particles by sieve analysis. Procedure: 1) Take a known quantity of the sample. Theory: Observation table: 2) Subject the sample for screening for a period of 1-10 minutes. 3) The various screens used in the sieve analysis are of the following sizes BS- 18, 30, 44, 60, 85, ) The sample collected on each screens are weighed. Sr.No. Mesh size Mesh mm opening retained gm fraction Cumulative mass fraction n.d n.d 2 n.d 3 n.d 4 1/d Figure:

8 Calculations: Find out n n.d n.d 2 n.d 3 n.d 4 Volume mean diameter = n.d 4 / n.d 3 Surface mean diameter = n.d 3 / n.d 2 Mean length diameter = n.d 2 / n.d n.d Arithmetic mean diameter= n Qs=Sphericity of the particle. es=density of particle. 6 x (area under the curve) Specific Surface = Qs x ep Draw a Graph of cumulative mass fraction Vs 1/d and obtain area under the curve. Results: 1. Volume mean diameter = 2. Surface mean diameter = 3. Mean length diameter = 4. Specific surface =

9 2.Ball Mill with dry material: A] Aim: To study and find out effect of the dry grinding and determine its critical speed and its efficiency. Procedure: 1. Determine the radius of ball mill and the balls. 2. Take a known weigh of feed and charge it into the ball mill along with the balls. 3. Close the lid of the ball mill. 4.Run the mill for known interval of time, withdraw the product and subject it to sieve analysis through 44 mesh and take its weight. 5. Mix the oversize and undersize of 44 mesh and charge the mixture into the mill again. 6. Repeat the procedure 4. Theory: Precaution: Before switch on the ball mill make sure that the lid is tightly bolted. Observation table: Sr.No. Time of grinding (min) 1 2 of product passing through 44 mesh (gm)

10 3 4 Figure: Calculations: 1. Radius of mill = 2. Radius of ball (inner)= 3. Weight of feed = Critical speed (η c )= 1/2Π [g/(r-r)] Where η c = speed critical of ball mill. g= Gravitational force. R= Radius of the mill. r= Radius of the balls. Output mass 4. Efficiency of ball mill = η= Input mass Results: 4.Ball Mill with wet material: A] Aim: To study and find out effect of the wet grinding and determine its critical speed and its efficiency. Procedure: 1. Determine the radius of ball mill and the balls. 2. Take a known weigh of feed and charge it into the ball mill along with the balls. 3. Close the lid of the ball mill. 4.Run the mill for known interval of time, withdraw the product and subject it to sieve analysis through 44 mesh and take its weight. 5. Mix the oversize and undersize of 44 mesh and charge the mixture into the mill again. 6. Repeat the procedure 4. Theory: Precaution: Before switch on the ball mill make sure that the lid is tightly bolted. Observation table: Sr.No. Time of grinding (min) of product passing through 44 mesh (gm)

11 Figure: Calculations: 1. Radius of mill = 2. Radius of ball (inner)= 3. Weight of feed = Critical speed (η c )= 1/2Π [g/(r-r)] Where η c =Critical speed of ball mill. g= Gravitational force. R= Radius of the mill. r= Radius of the balls. Results: Output mass 4. Efficiency of ball mill = η= Input mass 4.Ball Mill with number of Ball changed. A] Aim: To study the effect of grinding with change in number of balls and determine its critical speed and its efficiency. Procedure: 1. Determine the radius of ball mill and the balls. 2. Take a known weigh of feed and charge it into the ball mill along with the balls. 3. Close the lid of the ball mill. 4.Run the mill for known interval of time, withdraw the product and subject it to sieve analysis through 44 mesh and take its weight. 5. Repeat the procedure by changing the no. of balls with the same of weight of Theory: material. Precaution: Before switch on the ball mill make sure that the lid is tightly bolted. Observation table: Sr.No. Time of grinding (min) of product passing through 44 mesh (gm)

12 4 Figure: Calculations: 1. Radius of mill = 2. Radius of ball (inner)= 3. Weight of feed = Critical speed (η c )= 1/2Π [g/(r-r)] Where η c =Critical speed of ball mill. g= Gravitational force. R= Radius of the mill. r= Radius of the balls. Output mass 4. Efficiency of ball mill = η= Input mass Results: 5.Jaw Crusher: A] Aim: To study and determine crushing efficiency, reduction ratio, and power required. Procedure: 1. Take 5-6 pieces of brick. 2. Note the weight of each piece and the corresponding equivalent diameter. 3. Feed the brick piece one by one to the jaw crusher and collect the total crusher material. 4. Note the total time of crushing. 5. Subject the crushed material to sieve analysis. 6. Take weight of material retained on each screen. Theory: Observation table: A) For Feed Sr.No of Feed (gm) Volume of Feed Fraction Equivalent Diameter n.d 3 n.d 4

13 B) For Product Sr.No mesh number Mesh opening Retained Fraction n.d 3 n.d 4 Figure: Calculations: A) For Feed Calculate n.d 3 = n.d 4 = Volume mean diameter = B) For Product Volume mean diameter = Volume mean diameter of feed Reduction Ratio= Volume mean diameter of product Power Required: Power Required= x Wi x M [{ 1/ [Dp(P)] }-{ 1/ [Dp(F)] }] Where M= of feed to be crushed tons per hr. Wi= Working index of brick. Dp (P)= Volume mean diameter of product = n.d 4 / n.d 3 Dp (F)= Volume mean diameter of Feed = n.d 4 / n.d 3 Results:

14 6. Double Deck Vibrating screen: A] Aim: To determine the efficiency of a double deck-vibrating screen. Procedure: 1. Subject the feed to sieve analysis and measure feed retained on screen. 2. Mix the feed retained and charge the given mixture gradually through hopper. 3. Collect the overflow and underflow on the top of screen. 4. Subject this overflow and underflow to sieve analysis separately. 5. Weigh the particles retained on each screen after sieving for over flow and under flow Theory: Observation table:

15 Sr. No Mesh No. retained of feed (gm) fraction (XF) retained overflow (gm) fraction (XD) retained underflow (gm)1 fraction (XB) Calculations: Calculate: XF = XD = XB = (XF-XB) (XD-XF) XD (1-XB) η = (XD-XB) 2 (1-XF) XF Where η = Overall efficiency. Result: The efficiency of double deck vibrating screen is = % 7.Batch Settling. A] Aim: To plot a batch settling curve for given slurry and to study the effect of diameter of vessel on settling. Procedure: 1. Prepare a given weight percentage slurry. Theory: Observation table: 2. Add a pinch of KmnO4 for distinction of settling down. 3. The mixture in two columns is allowed to settle down at given time interval. 4. The readings are noted till complete settling take place. 5. The readings are to be noted simultaneously in the both column. Sr. No. Time (second) h1 (cm) h2 (cm)

16 Draw a graph of height Vs time. Result: Comment on the nature of graph. 8.Sigma Mixer. A] Aim: To study the working of mixer and determine its mixing index. Procedure: 1.Take 2000gm of sand and pour it in mixing trough. 2. Take 1000gm of tracer red colour. 3. Drop it in any one corner of the casing. 4. Now start the mixer for 5 min. 5. Stop the mixer and take appox same quantities of mixtures From any 7 points in the casing. 6. Take weight of each sample and sieve it.

17 7. Measure the overflow(sand) and underflow(tracer). Theory: Observation table: Sample. No Wt of sample gm Wt of sand in sample Wt of tracer in sample Wt fraction of tracer Xi Xi 2 Calculations: IP = (N-1)Xa (1-Xa) ((0.942X) Xi 2) X a overall fraction of tracer. Result: Conduction of Viva-Voce Examinations: Teacher should take oral exams of the students with full preparation. Normally, the objective questions with guess are to be avoided. To make it meaningful, the questions should be such that depth of the students in the subject is tested Oral examinations are to be conducted in co-cordial environment amongst the teachers taking the examination. Teachers taking such examinations should not have ill thoughts about each other and courtesies should be offered to each other in case of difference of opinion, which should be critically suppressed in front of the students. Submission: Document Standard: A] Page Size A4 Size B] Running text Justified text

18 C] Spacing 1 Line D] Page Layout and Margins (Dimensions in Cms) Normal Page Horizontal Desription Font Size Boldness Italics Underline Capitalize College Name Arial Yes Document Title Tahoma Document Subject Century Gothic Capital Class Bookman old Slyle Document No Bookman old Slyle Copy write inf Bookman old Slyle Forward heading Bookman old Slyle Yes Capital Forward matter Bookman old Slyle Lab man Contents title Bookman old Slyle Yes Capital Index title Bookman old Slyle 12 Yes Yes Capital Index contents Bookman old Slyle Heading Tahoma 14 Yes Yes Yes Running Matter Comic Sans MS Evaluation and marking system: Basic honesty in the evaluation and marking system is absolutely essential and in the process impartial nature of the evaluator is required in the examination system to become popular amongst the students. It is a wrong approach or concept to award the students by way of easy marking to get cheap popularity

19 among the students to which they do not deserve. It is a primary responsibility of the teacher that right students who are really putting up lot of hard work with right kind of intelligence are correctly awarded. The marking patterns should be justifiable to the students without any ambiguity and teacher should see that students are faced with unjust circumstances.