{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

L10-11_Material_Balances

L10-11_Material_Balances - Material and Energy Balances...

This preview shows pages 1–8. Sign up to view the full content.

1 Material and Energy Balances 03/21/10 Mass Balance Calculations

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
2 Material and Energy Balances 03/21/10 Objectives At the end of this chapter, you should be able to: Apply material balances for simple systems Formulate and solve material balance problems
3 Material and Energy Balances 03/21/10 Mass Balance Calculations All material balance problems are variations on a single theme: Given values of some input and output stream variables, derive and solve equations for others. Deriving the balance equations from a description of a process and a collection of process data may be considerable difficult A procedure for reducing a description of a process to a set of equations that can be solved will be outlined in this lecture.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
4 Material and Energy Balances 03/21/10 Flowcharts The catalytic dehydrogenation of propane is carried out in a continuous packed bed reactor. One thousand kilograms per hour of pure propane is preheated to a temperature of 670 o C before it passes into the reactor. The reactor effluent gas, which includes propane, propylene, methane and hydrogen, is cooled from 800 o C to 110 o C and fed to an absorption tower, where the propane and propylene are dissolved in oil. The oil then goes to a stripping tower in which it is heated, releasing the dissolved gases; these gases are recompressed and sent to a distillation column in which the propane and propylene are separated. The propane stream is recycled back to join the feed to the reactor preheater. The product stream from the distillation column contains 98% propylene, and the recycle stream is 97% propane. The stripped oil is recycled to the absorption tower.
5 Material and Energy Balances 03/21/10 Flowcharts The best way to organize the information convenient for calculations is to draw flowchart of the process A flowchart is drawn using boxes or other symbols to represent process units (reactor, mixers, separation units, etc.) and lines with arrows to represent inputs and outputs.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
6 Material and Energy Balances 03/21/10 Flowcharts - Example Suppose a gas containing N 2 and O 2 is combined with propane in a batch combustion chamber in which some of the O 2 and C 3 H 8 react to form CO 2 and H 2 O, and the product is then cooled, condensing the water. The flowchart of the two unit process might appear as shown. COMBUSTION CHAMBER CONDENSER 1000 mol O 2 3760 mol N 2 100 mol C 3 H 8 200 mol H 2 O 50 mol C 3 H 8 750 mol O 2 3760 mol N 2 150 mol CO 2 50 mol C 3 H 8 750 mol O 2 3760 mol N 2 150 mol CO 2 200 mol H 2 O
7 Material and Energy Balances 03/21/10 Flowcharts A flowchart of a process can help get material balance calculations started and keep them moving To do this, the chart must be fully labeled when it is first drawn, with values of known process variables and symbols for unknown variables being written for each input and output stream.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern