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Aeration Blowers in the Wastewater Industry in North America

Publisher: Aerzen USA Corp.

Format: PDF
Date: 2009-10-12

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Aerzen USA Corp.
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Overview:
Stating the fact that the economical operation of a wastewater treatment plant depends largely on the design and interplay of the aeration and process controls, this paper takes a pragmatic approach and presents information that will help the engineer to appropriately define both the design and the evaluation criteria of various blower technologies suited for wastewater aeration. Four types of blowers are examined; two dynamic and two positive displacement machines, including a comparison made specifically based on the treatment of wastewater. The paper details how energy usage minimization can be achieved by adopting the approach of right-sizing, defining the operating range and matching the blower technology to the application, and comparing operating data over time.

TABLE OF CONTENTS
1.2.	General	4
1.1.	Right-sizing	4
1.2.	Matching Aeration Blowers to Plant's Demands	5
1.3.	Real Plant and Operating Conditions	5
1.4.	Plug-and-Play Approach	5
1.5.	Total Costs	6
1.6.	Technologies Compared	6
2.	Defining the Field of Operation	6
2.1.	Site Conditions	7
2.2.	Type of Aeration System; Operating Pressure	8
2.3.	Variable Oxygen Need and Air Flow Range	10
2.4.	Blowers Control Scheme	10
2.5.	Flow Control	11
2.6.	Blower System Turn-Down Capability	12
2.7.	Other System Variables: Upstream and Downstream	14
2.8.	Machine Selection: Thermodynamic Performance	16
2.8.1.	Type of Compression	16
2.8.2.	Performance Characteristics	17
2.8.3.	Compression Formulae	17
2.8.4.	Efficiency	19
2.9.	Drive System	21
2.9.1.	Power Factor	22
2.10.	Other Points to Consider	23
2.10.1.	Additional Accessories	23
2.10.2.	Tolerance on Flow and Power	23
2.10.3.	Standstill vs. Idle	23
3.	Differences between the Blower Technologies	24
3.1.	Principle of Operation	24
3.1.1.	Rotary Lobe Blower	24
3.1.2.	Centrifugal or Turbo Blower	24
3.1.3.	Rotary Screw Compressor	25
3.2.	Comparison of Machines	26
3.2.1.	Rotary Lobe Blowers	26
3.2.2.	Single-Stage Oil-Free Screw Compressors	26
3.2.3.	Standardized Single-Stage High-Speed Turbo Blowers	26
3.2.4.	Special Purpose Single-Stage High-Speed Centrifugal Blowers	27
3.2.5.	Overview	27
4.	Examples	31
4.1.	Energy Usage for Three Different Types of Blowers	31
4.2.	Evaluation in a Typical Application with Multiple Machines	31
5.	Conclusion	33