A few years earlier, Capitol Aggregates had permanently shut down its wet kiln. In 2010 the plant still had the additional grinding capacity, and Capitol was looking to gain an extra 10% production from the existing calciner system as the market improved. FLSmidth approached them with a recommendation for how to achieve it.
“We know the next-generation coolers are much better in terms of heat recovery as well as maintenance,” says Gerry McKervey, Plant Manager, Capitol Aggregates.
GERRY MCKERVEY
While reliable, Capitol’s existing cooler – an FLSmidth CFG (Controlled Flow Grate) cooler – would not have supported any significant production increases. The new FLSmidth Cross-Bar Cooler upgrade puts Capitol in the position to achieve the extra 10% capacity once they make further modifications to their pyro system.
“Even though this new cooler is capable of cooling more clinker, we have bottlenecks in other parts of the pyro system,” says McKervey. “It’s a two-step process. This first step didn’t give us any capacity, but it was necessary to be able to go to the second step. Now we’re working with FLSmidth to do the other things that are necessary.”
Making the best better
The FLSmidth Cross-Bar Cooler represents the latest evolution in cross-bar technology. It takes the best elements of proven FLSmidth cooler designs and refines them even further – resulting in a cooler that gives the highest standard in clinker cooling technology at a highly attractive investment level.
Similar to previous cross-bar coolers from FLSmidth, which revolutionised the way clinker coolers are installed, operated and maintained, the FLSmidth Cross-Bar Cooler features a stationary grate line with no undergrate spillage or conveying system, separation of the conveying and cooling systems, air distribution plates with mechanical flow regulators, and modular construction. In the FLSmidth Cross-Bar Cooler, all cross bars are movable and reciprocate so as to optimise transport efficiency and enable horizontal installation.
“It’s a new cooler but not a new cooler,” explains Steven Miller, Product Manager, Pyroprocessing Technology at FLSmidth Inc. “It’s based on proven cross-bar technology and is an evolution of the design that grew out of feedback from having sold more than 230 cross-bar coolers.”
A thorough assessment
As always, FLSmidth reviewed the customer’s entire layout from a mechanical, operational, civil and construction standpoint before deciding how to proceed – and in this case the back portion of the old cooler casing was reused. But atypically, Capitol was in no rush since the upgrade was scheduled for their winter shutdown.
“By using extensive 3D modelling on the project, we found some interferences we were going to have early on and made some modifi cations to our equipment to avoid installation problems,” says Miller – an approach that was much appreciated by the customer.
“The 3D modelling really showed the sequence of events for the demolition and reinstallation and gave everybody a good idea of exactly what was going to happen in what order,” says Capitol’s McKervey.
A team approach
Asked to sum up how FLSmidth handled the project and process in three words, McKervey didn’t hesitate: “Professional, dependable and cooperative.”
Before
- FLSmidth CFG (Controlled Flow Gate) cooler
- Sloped cooler with 37.5 m2 grate area designed for 1816 t/d
- Standard cooler loss: 118 kcal/kgcl
- Tertiary air temperature: <700°C (separate take-off)
- Fan power consumption: high!
After
- FLSmidth Cross-Bar Cooler with ABC fixed inlet (8x61)
- Horizontal cooler with 44.2 m2 grate area (+18%) designed for 2000 t/d
- Standard cooler loss: 96 kcal/kgcl
- Tertiary air temperature: >900°C (common kiln hood) while maintaining similar secondary air temperature
- Fan power consumption: (-20%)
FLSmidth’s Miller is equally positive about the client: “The long relationship with Capitol is an important part of the story,” he says. “The relationship covers both many years and many equipment solutions. In fact, virtually the entire plant has run on FLSmidth equipment since its initial startup over 25 years ago.”
Miller continues: “The fact that they were willing to make this upgrade when we approached them rather than them being the ones to approach us shows their trust. They had equipment that was working very well for them, and they were willing to take a leap of faith with a new design to get the latest technology. That’s a reflection of their comfort with FLSmidth.”
Positive results
With the new FLSmidth Cross-Bar Cooler in place, Capitol has experienced significant improvement in both thermal efficiency and power consumption: an increase in tertiary air temperature to over 900°C, and reduction in fan power by 20%.
McKervey adds that the cooler vent system is running with only about half the excess air as before. The cooler is set up for a future production increase to 2000 t/d, and there have been no unplanned shutdowns due to the new cooler since its installation in April 2010.
GERRY MCKERVEY Plant Manager, Capitol Aggregates