Lecture 1 engineering methodology BME 211 2011 with narration

Lecture 1: 

Engineering Methodology Lecture 1

Methodology for solving Engineering Problems: 

Methodology for solving Engineering Problems Corn-steep liquor contains 2.5 wt% dextrose and 50 wt% water; the rest of the liquor stream is solids. The beet molasses contains 50 wt% sucrose, 1.0 wt% dextrose, and 18 wt% water; the rest of the molasses stream is solids. The beet molasses is mixed with corn-steep liquor in a mixing tank. Water is also added to the mixing tank to produce a dilute sugar mixture. The exit stream contains 2.0 wt% dextrose and 12.6 wt% sucrose, and is ready to be fed into a fermentation unit. See Fig. 3.24. What is the basis (an inlet or outlet flow rate) in your solution to this problem? What are the weight percents (wt%) of dextrose, sucrose, solids, and water in the exit stream? What is the ratio of the mass flow rate of water to the mass flow rate of the corn-steep liquor stream?

Engineering Problem Solving Method: 

Engineering Problem Solving Method 1. Assemble 2. Analyze 3. Calculate 4. Finalize

Methodology for solving Engineering Problems: 

Methodology for solving Engineering Problems 1. Assemble FIND: Diagram: System, Surroundings, System Boundary Calculation Table:

Methodology for solving Engineering Problems: 

Methodology for solving Engineering Problems 2. Analyze Assumptions: Extra Data: List Variables and Notations: State Basis: Chemical Reactions: Stoichiometrically balance

Methodology for solving Engineering Problems: 

Methodology for solving Engineering Problems 3. Calculate Equations Simplify Solve Finalize State the answers clearly Units/significant digits Check your answer Back substitution, Order of magnitude, test of reasonableness Make conclusions based on the results of your calculation

Assemble: Find & Diagram: 

Assemble: Find & Diagram Corn-steep liquor contains 2.5 wt% dextrose and 50 wt% water; the rest of the liquor stream is solids. The beet molasses contains 50 wt% sucrose, 1.0 wt% dextrose, and 18 wt% water; the rest of the molasses stream is solids. The beet molasses is mixed with corn-steep liquor in a mixing tank. Water is also added to the mixing tank to produce a dilute sugar mixture. The exit stream contains 2.0 wt% dextrose and 12.6 wt% sucrose, and is ready to be fed into a fermentation unit. See Fig. 3P.1. What is the basis (an inlet or outlet flow rate) in your solution to this problem? What are the weight percents (wt%) of dextrose, sucrose, solids, and water in the exit stream? What is the ratio of the mass flow rate of water to the mass flow rate of the corn-steep liquor stream?

Diagram and Find: 

Diagram and Find System Mixing Tank Corn Steep Liquor 2.5 wt% dextrose 50 wt% water 47.5 wt% solids 1 2 Beet Molasses 50 wt% sucrose 1 wt% dextrose 18 wt% water 31 wt% solids 3 4 Water Boundary 2 wt% dextrose 12.6 wt% sucrose ? wt% water ? wt% solids Find: Basis, wt% of stream 4 of water, sucrose, dextrose, and solids, ratio mass flow rate water/corn steep liquor

Assumptions: 

Assumptions 1) Open 2) Steady state 3) No reactions No material consumed within system No material generated within system No Extra Data needed

Analyze: 

Analyze Basis Set M 1 = 100 kg/hr

Calculate : Equations: 

Calculate : Equations Corn-steep liquor contains 2.5 wt% dextrose and 50 wt% water; the rest of the liquor stream is solids. The beet molasses contains 50 wt% sucrose, 1.0 wt% dextrose, and 18 wt% water; the rest of the molasses stream is solids. The beet molasses is mixed with corn-steep liquor in a mixing tank. Water is also added to the mixing tank to produce a dilute sugar mixture. The exit stream contains 2.0 wt% dextrose and 12.6 wt% sucrose, and is ready to be fed into a fermentation unit. See Fig. 3P.1. What is the basis (an inlet or outlet flow rate) in your solution to this problem? What are the weight percents (wt%) of dextrose, sucrose, solids, and water in the exit stream? What is the ratio of the mass flow rate of water to the mass flow rate of the corn-steep liquor stream?

Calculate: 

Calculate mf mass fraction m stream flow rate

Slide 14: 

Dextrose Sucrose Water Solids Sum of mass fractions in stream 4 Flow rates

Finalize: 

Finalize The basis was selected as the mass flow rate of stream 1 as 100 kg/hr The weight percents of each component in the exit stream are Dextrose: 0.02 Sucrose: 0.13 Solids: 0.41 Water: 0.44 The ratio of the mass flow rate of water to the mass flow rate of the corn-steep liquor stream is 0.07.

Finalize: 

Finalize m1+m2+m3=m4 back subsitition 100+36+7=143 Flow rates are conserved flow in equals flow out Dextrose+sucrose+water+solid for exit stream = 1 0.44+0.41+0.13+0.02 = 1 check Discuss and Draw conclusions.