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Module 1: Basic Concepts - Dimensional Calculations - Practice Problems

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Instructions:: Work these problems on a sheet of paper and check your answers against those provided below.

#1: Knowing the mass and density of a substance, how would you calculate its volume?

: Answer: Volume = Mass 1/Density; Solution:

#2: The flow rate of a gas stream through an air pollution control system determines the length of time that the control device has to remove the pollutants. This duration is called the treatment time or residence time. Given the gas flow rate through an air pollution control device (in actual ft³/min) and the volume of the control device (in ft³), what dimensional calculation would you make to get the treatment time?

: Answer:; Solution:; Treatment time is expressed in units of time; (i.e. minutes in this problem).

#3: Given the gas flow rate from a stack expressed in actual ft³/min and the area of the stack discharge expressed in ft², what dimensional calculation would you make to get the stack velocity?

: Answer:; Solution:; Velocity is expressed as distance per time. Using the units in this problem, the stack velocity would be expressed as ft/min.

#4: What is the residence time of a gas stream in an electrostatic precipitator if it has a volume of 90,000 ft³ and a gas flow rate of 8,100 actual ft³/sec?

: Answer: 11.11 sec; Solution:

#5

The average stack velocity has been measured at 50 ft/sec, and the gas flow has been calculated as 8,400 actual ft³/min.

What is the velocity in units of meters per second?
What is the gas flow rate in actual cubic meters per minute?

Answer: i. 15.24 m/sec

Solution:

Answer: ii. 237.87 m³/min

Solution:

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