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Module 5: Flowcharts and Ventilation Systems
Industrial process systems consist of the process equipment, which generates the pollutants, the air pollution control equipment that removes them, and the fan that moves the gas stream.
The process equipment and the air pollutant control devices do not work independently. The operating conditions of all the system components are closely linked together by the fans, hoods, and ductwork.
In addition to discussing how hoods and fans operate in an industrial system, this Module introduces you to the preparation and use of industrial source system flowcharts. Flowcharts provide an important tool for evaluating the overall system.
Some reasons for understanding and evaluating the entire industrial process as a whole are given below.
- Changes in the process equipment can have a major impact on the efficiency
of the control device.
- Changes in the air pollution control device can affect the ability
of the process hoods to capture the pollutants at the point of generation.
- The operating data from one unit in the system can be valuable in
evaluating the operating conditions in another unit in the system.
- Hoods and fans can influence the efficiency of the air pollution control equipment and the release of fugitive emissions from the process equipment.
After completing this Module, you will be able to do the following:
- Evaluate operating data on flowcharts to identify (1) possible system
abnormalities and (2) health and safety dangers that may be encountered
during on-site field work.
- Describe the factors that affect hood capture effectiveness.
- Determine if the necessary hood capture velocity is being attained.
- Calculate the transport velocity and explain its importance.
- Use hood static pressure and fan motor currents to evaluate hood
capture effectiveness.
- Evaluate gas flow rate changes using fan characteristic curves and system characteristic curves.
References
American Conference of Governmental Industrial Hygienists. 1998. Industrial Ventilation - A Manual of Recommended Practice, 23rd Edition. American Conference of Governmental Industrial Hygienists, Inc.
Cengel, Y. A. and M. A. Boles. 1989. Thermodynamics: An Engineering Approach. McGraw-Hill.
