CHE 311:Introduction to Chemical

Processing

Jeff Heys2:40-3:55 pm

PS H152

A little about me …

Office: ERC 287Office hours: Monday 9:30 – 11:30 and

Wednesday 1:00 – 2:00Office phone: 480-965-0874Email: heys@asu.eduI have two young children, so do not call my home after 8:00 pm, please.

About you…

I plan to learn your name, so please use the provided name plate till the first midterm exam.If you elect to not use the name plate, I will feel compelled to call on you so that I can learn your name by alternative means.It is in your best interest to meet your professors/instructors.

FAQ for this course…

1. Are the prerequisites important? No, you only need to be an algebra “ninja” and be very good at balancing chemical equations. Much of the chemistry terminology will also be important.

2. Do I need to purchase the expensive textbook? Probably, homework will be assigned from the book and it will be an important reference, but, technically, you can get through the course without it.

FAQ

3. How will I be evaluated – i.e., how are grades determined? Homework is 30%, there are two midterms at 20% each, and a final worth 30%. Class participation may help in borderline cases.

4. Homework? Yes, your 10 best homework grades will count (but I only plan to assign 10 or 11 homeworks). Please work with others on the homework, but do NOT copy from any source. Assignments are posted on the course website.

FAQ

5. How should I prepare for exams? Old exams from the instructor do not exist. The assigned homework problems are, by far, the best resource. At least one homework problem will appear on each exam.

6. Is there are curve? Hopefully not, but if the class average is below a C+, grades will be curved up to approximately that level.

FAQ

7. Late homework? Accepted, but the late penalty is steep at 25% per day (weekends excluded).

8. How much of the text will be covered? Approximately the first 9 chapters, but the first 3 chapters will be skimmed quickly even though you should know the information in those chapters.

FAQ

9. I need help, what should I do? First, start the homework, which will normally be due on Wednesday, early so that you can utilize the office hours. Second, work with a group. Third, it may be possible to hire a tutor. Fourth, do more problems (scrimmage). Fifth, know when to fold (i.e., withdraw while you can).

FAQ

10. What does a chemical engineer do? Read chapter 1.

11. What will we learn in this class? The basics of mass and energy balances –the foundation of engineering and many of the sciences. More on this later, but, remember, the tools learned here will be used extensively in other class, so learn them well.

FAQ

12. Why is this class so focused on a single concept (i.e., why is it so monotonous)? See movie clip….

FAQ

13. Why is this class so freaking hard? I haven’t left the library for 4 days? Three reasons: (1) the material is the foundation for all of chemical engineering, and it must be mastered, (2) we (the chemical engineering faculty) do not want a senior to fail a course, and (3) I want you to know what you are capable of doing (be the best you can be).

FAQ

14. Will the lectures be posted online? No, only this first lecture will be presented using the computer. Most other lectures will be presented on the chalkboard as they are focused more on problem solving and less on pure information exchange. You are free to borrow my notes for photocopying provided you have a reasonable excuse.

FAQ

15. Classroom guidelines? A few…never, ever, answer a cell phone. If it rings more than once or twice a semester your grade will suffer. If you are late or leave early, please sit near the door. Habitual tardiness will affect your grade. Explaining your tardiness after class will help. Keep laptops near the back.

FAQ

16. Why do you hate Microsoft? I don’t hate Microsoft. I believe they sold an operating system that was inferior to the alternatives for many years, and they charged a lot of money for it. Their current OS, which is on this computer, is secure, stable, and still expensive. I also believe that near monopolies are bad for consumers even though I consume lots of Starbucks coffee.

FAQ

17. Okay, so then why don’t you post Word documents (*.doc) or Powerpointdocuments (*.ppt)? Because then I’m requiring you to spend $$ on MS Office. I believe that people should only exchange files using formats that have published interpretations or specifications (i.e., *.html, *.txt, *.pdf, *.tex, or any of the open document formats).

FAQ

18. I paid for a 75 minute lecture, but you almost never give me what I paid for, instead I get a measly 65 or 70 minute lecture? First, I like to leave a little time at the end for questions. Second, in my experience, no one listens for the last 5 minutes. Third, I’m trying to encourage you to start on the homework while the material is fresh in your mind. Fourth, there usually isn’t a single H2O molecule left in me after 70 minutes of lecturing.

Course Goals

1. Learn the language of chemical engineering

2. Turn problem statements into pictures3. Turn pictures into equations4. Solve the equations5. Analyze the solutions

A Black Box…

For most of this course, we won’t be concerned with the details of chemical processing equipment. Instead, we will draw a boundary, which defines a system, around the region of interest.

OutputsInputs

System

System or Black Box

May contain multiple pieces of equipment.May be a fixed size or a variable size.May contain chemical reactions

Mass Balance

Let’s assume there are no chemical reactions.Let’s assume the process is operating continuously at steady-state (all time derivatives are equal to zero).Let m be the mass flow rate (kg/s)

outin mm && =

Mass Balance

Let’s assume there are no chemical reactions.Let m be the mass flow rate (kg/s)

outinonaccumulati

mmdtdm

outin

−=

−= &&

General Mass Balance

For a single species created or destroyed by a chemical reaction… (equation 4.2-1 in text)

nconsumptiogenerationoutinonaccumulati −+−=

Example

First, we have to pick a system…lets use my skin as the boundary of a system consisting of me…We’ll do a TOTAL mass balance, and since mass cannot be created or destroyed (only individual chemicals can be reacted into or out of existance), the generation and consumption terms are zero.At noon on August 9, 2005, I weighed 190 lbs.

Example

I consumed: 96 oz. of liquid (6 lbs)32 oz. of food (2 lbs)

I excreted (assuming 1 lb. per flush):7 lbs (7 flushes)

Example

At noon, August 10, 2005, I weighed 190 lbs.

Accumulation = 0 lbs.

In – Out = 8 lbs. – 7 lbs. = 1 lbs.

Why aren’t they equal?

This will change the way you think…

In “The Matrix”, we’re told that the machines use people as an energy source, which is possible, and that they feed people ground up dead people, which is also possible. So, an energy balance on a single person does not violate any physical laws.But, what if we do an energy balance on all the people as a single, steady-state system…

For next time…

Read chapters 1, 2, and 3Review unit conversion (pay special attention to lbf vs. lbm)Significant digits (??)We will not be specifically covering chapters 1 and 2 in class. We will cover chapter 3 on Wednesday.

Before we end…

Write down a question that you have about this class or about what we covered today.