Position: In this page, you will learn a mobile control system for belt scale/weigher testing:
* Reduce burden of required periodic scale testing for certification
* Reduce or eliminate costly errors
* Enable more frequent testing through use of a mobile system
The requirements for maintaining a belt scale to measure coal flow are rigorous, requiring substantial labor, time, and financial investment. Current periodic material tests, conducted to comply with NIST handbook 44, temporarily render the coal delivery system unavailable.
This project will investigate the viability of a faster, accurate mechanism for belt scale testing – a mobile material test system which would reduce the burdens of coal scale testing and improve the quality of belt scale measurements while ensuring compliance with certification requirements.
Value
Material testing to certify coal belt scales is very laborintensive and costly – as much $20,000 or more per test.
These tests are conducted at least once a year on each certified scale and require a huge coordinated effort among coal yard and coal delivery staffs, in addition to the advance preparation. To conduct a material test, the site needs a separate calibrated weighing system for trucks or rail cars.
Maintaining that independent calibrated scale requires a significant commitment and expense. Less-intensive simulated belt scale tests, via chains or electronic methods, can be used for monitoring the scale but cannot be used for belt scale calibration, certification, or adjustments.
In addition to the certification requirements for commercial scales, errors may result in payments for fuel that was not received. For example a 1% error in the measurement of coal entering a typical 500 MWe power plant translates to $700,000 a year in additional fuel costs. Fuel costs represent the largest portion of expenditures required to operate a plant.
A mobile test system could be used by power generating companies at multiple power plants throughout their fleets. More frequent belt scale testing would catch drift and other measurement errors sooner, saving fuel costs and reducing bookkeeping required for step-change increases or decreases in fuel inventories. This system also could possibly be applied to scales used to measure limestone used for FGD. The typical plant mentioned earlier, equipped with a FGD, uses 100,000 tons of limestone annually; a 5% error may cost as much as $60,000/year.
However, it is not yet possible to quantify the potential benefits of a mobile test system. The cost to build, operate, and maintain these systems is unknown, as they are not currently commercially available.
Drivers and Trends
For many power plant owners and operators, conveyor belt scales are a primary means to monitor material delivery to detect and prevent potential fraudulent or inadvertent material delivery errors for a multitude of materials from coal to limestone. To ensure belt scale certification, material tests must be conducted annually and temporarily render the coal delivery system unavailable. Those tests are labor-intensive and cost as much as $20,000. And if the certification testing identifies an error, readings could have been affected for as much as a year, substantially increasing the cost.
Project Summary
This project will be conducted in two phases. The first phase will include:
* A feasibility study of a potential mobile belt scale system
* Definition of the requirements of such a system
* Development of specifications based on those requirements.
* Development of estimates for the capital costs
* Development of estimates for operating and maintenance costs
* Definition of benefits of using the system on a coal plant fleet.
This conceptual system will be sized to test belt scales on coal conveyors moving material flows up to 4,000 tons/hour and also may be deployed on conveyors moving limestone, or biomass.
If this evaluation warrants the development of a prototype, a separate second phase will include:
* Development of a detailed design of a mobile coal scale test system, based on the conceptual design developed in Phase 1.
* Fabrication of a prototype system
* Field testing of the prototype at several different power plants coal yards
Deliverables
All participants will receive a report summarizing the feasibility study, which will include:
* A list of requirements needed in a mobile system
* Specifications of a system to fulfill those requirements
* An estimate of the system’s capital cost
* An estimate of the system’s O&M costs
* Defined benefits
Cost of Project
The estimated total project cost for Phase 1, which includes the feasibility study and related evaluations, is $100,000. The cost to participate is $25,000. EPRI members may use Tailored Collaboration (TC) for up to half their contribution. Costs and timing of a second phase are not known at this time.
Project Status and Schedule
This project will start once it is fully funded and Phase 1 is expected to culminate with a technical update in 2010. Who Should
In addition, a quality belt scale controller is enable the scales work more safely and efficiently.
