COAL TO BIOMASS MILL CONVERSIONS USING STATIC CLASSIFICATION
|Coal Milling Projects|
Coal Milling Projects is a South African based company with 20 years’ experience in the Power industry primarily on coal fired Power Plants and more recently Biomass firing.Star CCM+
Coal Milling Projects uses Star CCM+ Computational Fluid Dynamics Software exclusively for all CFD modelling and has an extensive database of empirical mil operating data for model calibration and practical evaluation.Southwestern Corporation
CMP is a global partner of the Southwestern Corporation in the USA and reciprocally shares and develops Patented technology for use on Coal or Biomass Mills.Babcock e-Type Mill
The Drax UK 10E mill has been successfully converted using patented Rotating Throat technology and sophisticated CFD modelling. The Static Classifier has been completely modified to reduce recirculation and pressure drop build up and to match the Rotating throat flow characteristics.The requirement fort particle size and required throughput was achieved.
Burner Isolators isolate the mill and its associated components from the running boiler and possible flashback from the boiler through the pulverised fuel pipes. For this reason, Burner Isolators are situated as close as possible to the boiler.
The Isolators are closed during maintenance on the mill internals and primary air and pulverised fuel systems. Orifices are often required in pulverised fuel pipes to offset differences in total pipe length and balance pressure between the fuel pipes on each mill. The Burner Isolators are designed so that the housing will also accommodate an orifice plate.
Southwestern Burner Isolators comply with National Fire Prevention Association (NFPA) code requirements, being designed for 350 kPa service and tested at 1 400 kPa.
Coal Milling Projects (CMP) have the capability to design, fabricate and install transfer chutes and hoppers required for the handling of bulk materials. CMP was awarded the design, manufacture and installation of coal transfer chutes at both Arnot and Hendrina Power Stations. Subsequent to these projects CMP together with Aerotherm and Bulk Solids Flow SA developed the in-house capability to design chutes using proven coal specification analysis and Discrete Element Modeling (DEM) verification. This was put to use on the Kriel coal transfer chute design due for installation in 2012-2013. The Coal transfer chutes at Arnot where designed by CMP and have been operating successfully with the full range of coal conveyed including wet coal.
A full design of Coal Transfer systems is performed from material testing to 3D modeling from flow calculations and discrete element verification to the complete development of manufacturing drawings. This has been performed for Arnot, Hendrina and Kriel Power Stations coal handling plants.
Coal mill desander
MILLING PLANT SPECIALISTS FOR POOR COAL CONDITIONS
The Desander Patented Technology is used to extract heavy minerals out of the mill during the milling process. This has a major impact on the wear rate of the grinding elements and the down stream effects of boiler tube and duct erosion.
PROPERTIES OF COAL
Origins of high ash coal
Origins of high ash coal
Coal Milling Projects (CMP) are the agents for Merrick Industries a leader in the design manufacture an installation of slack belt type gravimetric belt feeders. CMP was awarded a contract to install 27 gravimetric belt feeder at Komati Power Station. In addition to this existing belt feeders can be converted to gravimetric using Merrick’s load cell technologies.
Other auxiliary products used in conjunction with coal feed systems such as blocked chute detectors, coal feed gates, diamond back hopper designs and feeder drive retrofits can be designed to your plant requirements.
The main purposes of the Southwestern High Performance Static Classifiers (HPSCs) are to improve coal fineness control and increase maximum mill throughput.
The HPSC design incorporates the following features to achieve these improvements: Mill Top Extension – to increase the volume of the mill housing and allow for installation of the cyclone separator Pre-swirl Vanes – to control airflow in the upper mill housing, thus increasing the efficiency of the classifier blades Intermediate Deflector Liner – to redirect the upwardly moving coal and initiate intermediate classification Enhanced Classifier Blades – larger than standard blades and contoured to fit the mill housing.
Cyclone Separator – to increase the classifier volume and to segregate larger coal particles from the coal stream.
Multiple Outlet Turret – to improve distribution to the pulverised fuel pipework.
Slew Ring Assembly – to allow on-load classifier vane changes from a single actuator.
Installations at Arnot, Camden and Matimba Power Stations have resulted in significant increases in mill throughput with improved fineness. At Matimba Power Station, the fineness improvement was 15% with an average throughput improvement of almost 21%. At Camden Power Station the maximum throughput has been increased to almost 30 tons per hour (tph), from a design rating of 22 tph. A trial installation has been done on the 12.9E mills at Matla Power Station with a 17% throughput improvement.
- Reduction in air velocity through the throat area
- More uniform air distribution in the grinding area
- Reduction in mill differential pressure
- Reduction in PA inlet pressure
- Reduced wear in the throat area
- More efficient mill operation, typified by an increase in reject rate and a reduction in mill and fan power
- Throat velocity can be changed by adding or removing restriction rings to alter the throat area