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Abstract
A full scale proto-type is being created. This model will allow was designed and built. It was built to scale to represent the alum doser as it is positioned in the entrance tank of an Agua Clara water treatment plant. The model allows us to run full flow/ full scale accuracy tests in the lab. Additionally, this the model will be taken to the EP3 conference this spring. With this proto-type we will be able to demonstrate the functionality and flexibility of our chemical doser.
Proto-type Design
The proto-type is made up comprised of two main components: the structural frame work and the moving lever-arm. The frame components are constructed using a modular aluminum framing system manufactured by 80/20 Inc. Affectionately called "The Industrial Erector Set," this company offers a wide variety of components along with a down-loadable Auto-cad plug-in of their components. With these tools, we have been able to design and evaluate multiple proto-types. Additionally, their the T-bar design of the framework extrusions will allow allows us to mount extra components with any standard "National Course" thread. All accessories are readily available and are purchased through McMaster-Carr.
The dimensions of the structural framework are based on the actual dimensions of the entrance tank of the Agalteca plant. We have reduced the width to 1/2 meter as a space/material-cost saving measure but otherwise accurately reflect the entrance tank dimensions. Entrance tank dimensions and elevation are a critical criteria in plant operations. Head losses throughout the plant must be accounted for in the entrance tank. Furthermore, the addition of the physical parameters of the rapid-mix tube has have added to the depth of the entrance tank. Full analysis of these parameters can be found on the Agalteca Page
The frame work also includes a table to hold a small stock tank and another table to hold the constant-flow devicehead tank. Ideally, as determined in the design of the constant-head devicetank, there should be 30 cm between the orifice and the low water lever of the stock tank. This dimension has been taken into account in our design. Figures 1.0 - 1.2 illustrate our prototype from various views and a full description of each component follows.
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Lever Arm
The lever arm is a 1" x 1" T-slotted aluminum-extrusion bar as classified by 80/20 Inc. as 1010. The length of the lever arm is a critical dimension for Alum dosing and is calculated in the Dual Scale Child page. This length of 0.80 meters accounts for the variation in the water level of the entrance tank resulting from changes in plant flow. The lever arm is attached the pivot rod with a clamp which is then attached to two side bearings on the frame. The accessories were purchased through McMaster Carr. The lever is positioned in such a way that the slide can be positioned directly under the pivot providing a manual shutoff.
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Stock Tank
The stock tank will sit on the triangular table that is pictured. The table for the stock tank was decided to be is 24.13 cm (9.5 inches) tall to provide enough head to demonstrate how our system works.
Constant Head Tank
The constant head tank is maintained on this makeshift platform that will place the tank at the same level as the lever arm.platform. The platform is adjustable by loosening the attachment points to allow accurate leveling. This is a critical height as the water level in this tank must be in line with the orifice when the lever-arm is horizontal.
The AutoCad Drawing can be viewed Here
h.3 Assembled Prototype
The prototype was assembled and hydraulic components attached. The following two drawings show the assembled structure and key components are labeled.
Useful Useful 80/20 information
80/20 Inc. is a manufacturer of modular aluminum framing system. 80/20 components are used extensively throughout our lab and specifically in this project. This section provides some details to assist getting started with these components and using them in design.
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- http://www.8020.net/Default.asp; Includes parts catalog, pricing list and Auto-cad Plug in
Deliverables
By the end of the semester we intend to have a functional, full scale non-linear chemical doser. In order to accomplish this, this sub-group needs to complete the following:
All semester goals were met concerning this aspect of the project and are summarized below:
- Proto-type was designed. Autocad drawing created
- Components ordered and received.
- Model assembled
- Hydraulic components attached including orifice, clip, stock tank and constant-head tank.
Outstanding
- As this is a model of what will ultimately be used in Honduras, the assembled model needs to be fully evaluated for ease and practicability of use. Additionally, components for the Honduran doser need to be purchased. Once accomplished, a full doser material list will be added to the wiki.
- Assemble components delivered by 80/20 Inc.
- Attach hydraulic components