Technical Bulletin 141. Installation and Maintenance Cost Evaluation. by:

Transcription

1 Technical Bulletin 141 Installation and Maintenance Cost Evaluation by: Environmental Dynamics International Published: 6/2005

2 BULLETIN BRIEF This Technical Bulletin and attached drawings illustrate the total system cost analysis comparison of alternate diffuser platforms, (tube, MiniPanel, disc, other). The industry recognizes three primary diffuser platforms (types), the disc, tube, and panel. EDI manufactures and supplies all three platforms to the industry. 1 A separate tube analysis is available on request. To allow an unbiased comparison of the characteristics and benefits of each platform only EDI diffuser systems will be analyzed and compared. Note: separate comparisons of benefits of one disc, tube or panel system versus a competitive system are also possible but beyond the scope of this general platform comparison. DISCLAIMER Technical Bulletins are presented as a service by Environmental Dynamics International headquartered in Columbia, Missouri USA. For additional more information regarding this particular bulletin or your specific aeration application contact Environmental Dynamics International by calling , toll free at EDI.AIR8 ( ), or via at [email protected]. 1 Only disc and MiniPanels shown in this example as each have similar performance based on equal AT/AD and equal air loading/sq m (ft 2 ) of membrane area. Tubes are not included in this analysis as the same AT/AD produces less SOTE. The same SOTE is available with tubes with significant increase in area of membrane. Tube systems have benefits on capital cost when same area of membrane but slightly reduced SOTE. 1

3 TECHNICAL BULLETIN 141 INSTALLATION AND MAINTENANCE COST EVALUATION All premium quality diffusers types (platforms) can give similar SOTE and mixing performance when properly applied and properly installed! EDI offers a full spectrum of diffuser platforms utilizing disc and MiniPanels to allow Customers, Engineers, and Market Partners to select diffuser platforms and develop systems optimized for each application. The following examples demonstrate the advantages/disadvantages comparison of three EDI diffuser platforms/configurations designed to offer similar performance/capacity. Examples selected show a typical layout drawing of each system with typical design, installation and operation data displayed for comparison. Items shown are key variables for evaluation of any diffuser platform. Considerable supplemental criteria are available from EDI on each of your projects to assist or reinforce your Diffuser Platform selection and design. For this typical example the analysis confirms the following: 1. MiniPanels, disc, or tubes can deliver the same SOTE. 2. All diffusers at same submergence. 3. Active diffuser area of each diffuser platform may vary (AT/AD) to match SOTE requirements. 4. Airflow stays constant. 5. Layout varies greatly. 6. Cost varies greatly. 7. Ease of installation ion and maintenance varies greatly. In addition to the economic comparison shown, there are many other variables that may be very important on any project. Partial List of Other Variables: Ease of Basin Drain and Clean Access for Operation and Maintenance Maximum Product In Basin Capacity Efficiency Strength of Materials and Systems Net Present Value (NPV) analysis of life cycle system cost EDI s Value Added Services will generally include an analysis of most variables for your reference. 2

4 All diffuser options presented compare two main cost items: Installation costs and maintenance costs. 1. Capital and Installation Cost a. System cost: the capital cost for the diffuser units, the piping, pipe supports, etc. b. Piping installation: time needed to install the piping system. c. Diffuser installation: time to install the diffuser units on the already installed piping system. 2. Maintenance Costs (Membrane Replacement) a. Membrane cost: the replacement cost for the diffuser membranes only. b. Maintenance time: the time needed to change membranes on this typical system. Please note: All installation and membrane replacement times are based on typical values from EDI and EDI Market Partner experience and may vary with the piping layout, experience, etc. Typical Disc Diffuser Platform (Case I) The EDI 9 inch (230 mm) disc platform shows a typical full grid disc system with either threaded as shown in Figure 1 or KlicLoc saddle mounted disc unit shown in Figure 2. 3

5 Figure 1 Figure 2 To achieve specified performances, a system active area diffuser (AD) of approximately ft 2 (17 m 2 ) is required, i.e., 441 of the 9 inch (230 mm) discs are needed (AD = ft 2 (0.038 m 2 ) per disc). Discs are mounted on 9 laterals with 49 discs each. To simplify the comparison of all options, all cost and time values of this full grid disc system are set to 100%. All other options will be compared to this 100% baseline disc diffuser grid reference. Optional Disc Diffuser Platform Model 8P (Case II) This is a special design with eight 9 inch (230 mm) diffusers mounted to create the Model 8P diffuser assemblies utilizing EDI special saddle mount which can typically be installed more efficiently. For details about this Model 8P diffuser type, see Figure 3 below. Figure 3 To achieve the same performance as the Case I disc arrangement, the same system AD of approximately ft 2 (17 m 2 ) is also required. Use 56 of the Model 8P diffuser units with a total of 448 nine inch (230 mm) discs. Model 8P assemblies are mounted on 2 laterals with 28 Model 8P duplex units each lateral. 1. Capital and Installation Cost a. System Capital Cost: offers approximately 10% savings versus standard disc option. Cost of additional parts (saddle, etc.) are offset with cost savings because of less piping and fewer pipe supports. 4

6 b. Piping Installation Time: reduced with 2 laterals and a subheader to be installed instead of 9 laterals and a subheader at the full grid disc system. A 75% savings in time to install the piping system is typical. c. Diffuser Installation Time: 56 Model 8P duplex units can be installed much faster than 441 nine inch discs if the saddles and diffusers on the Model 8P are factory mounted. Factory assembled Model 8P units offer 80% installation savings. Total field installation of saddles and diffusers is approximately the same as standard disc arrangement, i.e., zero savings. 2. Maintenance Costs (Membrane Replacement) Membrane Cost and Time: As the EDI Model 8P system consists of approximately the same number of 9 inch discs as a full grid disc system, no savings are achieved versus standard grid system. EDI MiniPanel Diffuser Platform (Case III) The EDI MiniPanel system is a top only perforated tubular diffuser with 4.5 inches (122 mm) OD and 58 inch (1359 mm) membrane length. It combines the benefits of a disc or panel diffuser with all the benefits of a tube diffuser, i.e., simple piping, easy membrane change, low stress on the membrane, etc. For details about the MiniPanel diffuser refer Figure 4 below. Figure 4 To achieve the same performance as the Case I or Case II disc systems, the same AD of approximately ft 2 (17 m 2 ) is also required. The MiniPanel diffuser units have AD = 2.54 ft 2 (0.236 m 2 ) per membrane = 5.08 ft 2 (0.472 m 2 ) per MiniPanel duplex unit with 36 units required. MiniPanels are mounted on 2 laterals and require only 18 MiniPanel duplex units each lateral. 5

7 1. Capital and Installation Cost a. System Capital Cost: because of the reduced number of diffusers and laterals, hardware cost savings of approximately 20% can be achieved compared to a full grid disc system. b. Piping Installation Time: same piping layout as the Model 8P system with same savings of approximately 75% versus typical disc grid configuration. c. Diffuser Installation Time: 36 MiniPanel duplex units are fully factory assembled and are even faster to install with approximately 95% savings. 2. Maintenance Costs (Membrane Replacement) a. Membrane costs are reduced versus discs at typical 20% savings. b. Membrane Replacement Time: Each MiniPanel membrane replaces approximately six 9 inch disc (230 mm) disc membranes. Major maintenance cost and time savings are achieved for membrane replacement with EDI MiniPanel system. Time savings of about 75% are typical. Combining all the cost and time saving benefits of the EDI MiniPanel system with the mechanical benefits the MiniPanel diffuser platform typically offers the most reliable and cost effective aeration solution. Refer to the chart below and subsequent figures 5-7 for more details. 6

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9 Figure 7 8