tailieunhanh - AERATION: Principles and Practice ( VOLUME 11 ) - Chapter 7

7 Kiểm tra và Đo lường Trong lịch sử, nhiều phương pháp đã được sử dụng để kiểm tra và xác định thiết bị sục khí. Theo thời gian, các phương pháp khác nhau đã dẫn đến sự nhầm lẫn và trình bày sai lệch hiệu suất thiết bị. Hơn nữa, các nhà cung cấp thiết bị, tư vấn, và người dùng thường sử dụng khác nhau danh pháp khi họ báo cáo khả năng thiết bị. Bảo lãnh thực hiện cho các thiết bị chuyển oxy từ lâu đã là chủ đề thảo luận sôi nổi bởi các kỹ sư trên. | -ĩ Testing and Measurement INTRODUCTION Historically many methods have been used to test and specify aeration equipment. Over time varied methodologies have led to confusion and misrepresentation of equipment performance. Furthermore equipment suppliers consultants and users often employ differing nomenclature when they report equipment capabilities. Performance guarantees for oxygen transfer devices have long been the topic of lively discussion by engineers all over the world. It is important that the engineer owner have some guarantee from the manufacturer ensuring efficient and effective performance of the proposed aeration equipment. In the design of an aeration system the engineer owner must first select a process or processes that will meet discharge permit requirements. There is substantial latitude in process selection but the choice is often made on the basis of engineer owner experience process and operational reliability and capital and operating costs. Often several alternatives may be initially selected and evaluations are made to objectively select the best system. It is likely that the oxygen transfer system will play an important role in this selection process since it usually represents a significant portion of the total process power cost. From that point of view it would be highly desirable for the engineer owner to obtain guarantees on aeration performance under actual process conditions. Typically once a process is selected the engineer may estimate actual oxygen requirements AOR which depends on wastewater characteristics mean cell residence time MCRT or F M and requirements for nitrogen transformations among other process variables see design example in Chapter 3 . The AOR is subsequently used to estimate the field oxygen transfer rate OTRy . If an in-process oxygen transfer efficiency guarantee is available usually expressed as mass time power or percent efficiency the engineer can estimate power requirements for each competitive system.