The cooler system allows an engineer to review various operating parameters via satellite and adjust set points in case any troubleshooting or fine tuning is required

Since 1951, Ciment Quebec Inc. (CQI) has operated a cement plant in St. Basile of Portneuf, on the north side of the St. Lawrence River, 50 km west of Quebec City, Canada. The wet process was used at the plant until the No. 5 clinker line was commissioned in 1983, at which time the old kilns were shut down.

The pyroprocess section of this line is equipped with a Fuller 4-stage preheater-precalciner, an Allis-Chalmers 4.88-meter-diam. × 42.7-meter-long (ratio 8.75:1) rotary kiln, and a Fuller 3-meter-wide × 19.8-meter-long grate cooler.

The nominal rated capacity was 2,300 mtpd at the time of commissioning, but various equipment additions, changes, and improvements over the years brought the production rate to 2,500 mtpd, with a high percentage of efficiency and an annual availability of about 330 days.

As these improvements were performed — with an eventual goal of 3,000-mtpd capacity in mind — and as the rotary kiln efficiency already was demonstrating that it can produce more than 3,000 mtpd of clinker, there was room for additional improvements if the bottlenecks at 2,500 mtpd were removed.

During the last three years, one of the main production bottlenecks was the clinker cooler which, by itself, was initially designed for 2,500 mtpd and was, therefore, limiting the increase in production rate, especially during the warm summer months.

In addition, the high level of maintenance done on the cooler during the annual winter shutdown always involved placing the cooler on the critical path of the repair schedule, thus limiting the possible reduction of that schedule.

Finally, as the markets served by CQI are especially demanding in terms of cement quality, keeping a good state of clinker quenching at the beginning of the cooling phase at levels of production above 2,500 mtpd is mandatory for assuring the best quality end product.

This last point also was considered when production went from 2,300 to 2,500 mtpd in 1994, when the clinker cooler was modified with the addition of an IKN Clinker Inlet Distribution System (KIDS) fixed inlet chute, replacing the first 10 rows of grate. This project was the first contact between CQI and the Germany-based IKN, and the installation of the KIDS was exactly in line with the tight schedule established at that time.

The operating results with the KIDS were good and met the expectations CQI had: to be able to handle as much as 2,500 mtpd with an exit temperature at the cooler discharge between 80° and 90°C and an improved quenching. In addition, the tertiary air, which was under 800°C before the KIDS installation, went up to more than 900°C, a significant energy gain.

In order to begin the gradual increase of the clinker production over 2,500 mtpd, the clinker cooler had to be changed. Various technical solutions were studied, and the new generation of coolers from different manufacturers were analyzed.

Because of CQI's positive past experience with the IKN KIDS and as IKN was proposing a solution that was more than satisfactorily addressing the production goals as well as the erection constraints inside an already existing building and short shutdown schedule, the contract was awarded to IKN at the end of July 2000.

The agreed upon scope of work was that the roof and external walls of the actual cooler as well as the clinker dust recuperation system under the cooler would be left alone, and a complete pendulum cooler arrangement would be designed to fit inside the existing cooler housing. However, the grate length would be extended by 4.2 meters, and the grate width would be increased from 3 to 3.2 meters for a total cooling area increasing from 53 to 66.2 sq meters.

At CQI's request, this cooler would be sized to handle 3,000 mtpd without additional modifications and to handle efficiently as much as 3,500 mtpd with modification of the tertiary air duct, kiln hood, and cooler roof and the addition of a heat shield in the cooler.

The hammer mill at the cooler discharge would be replaced with an IKN 4 roller crusher for a smoother, quieter, and cleaner crushing operation and better size uniformity of the clinker nodules. In addition, if a kiln upset produces a clinker ball that would normally block the hammer mill and need to be destroyed with a 8-gauge caliber gun, that ball would simply sit on the rollers of the new crusher and gradually be chewed up by the toothed rings of the rollers. Finally, all seven cooling fans would be replaced with new fans that have variable frequency drives.

In preparing for the contract proposal, two IKN engineers came on site in June 2000 to visualize the cooler building and elaborate a design that would allow the transformation to be done in this relatively tight space. Timing was crucial since the cooler had to be fabricated and delivered on site before Jan. 31, 2001, so it could be partly preassembled and ready to install for the planned Feb. 15 shutdown.

The objective was to not extend the shutdown schedule due to this major transformation, the planned schedule being 24 days of feed interruption: 21 days for dismantling of the existing cooler and installation of the Pendulum, one day of cooling, and nearly two days of preheating.

To save on the cost of the project, it was agreed that — based on IKN drawings — CQI would locally fabricate the housing for the extension of the cooler as well as the pendulum supports and the drive cylinder pier.

The cooler's general arrangement drawings for approval were submitted four weeks after the IKN team's visit to the plant site, and the drawings were approved by CQI and returned promptly to continue the momentum of the project schedule.

The movable frame, which is the heart of the Pendulum cooler, is held in place by self-supporting integrated cradle stands. A single hydraulic cylinder is provided to drive the sturdy frame.

All the components supplied by IKN arrived on site at the beginning of January 2001. A field erection engineer from IKN came a few days later to supervise the pre-assembly of the components by CQI personnel. This step was helpful to CQI's production and maintenance people in getting acquainted with the fabrication and design of the equipment.

As the parts were painted by IKN under the specific painting code provided by CQI, the shipment even included some additional paint for the touch-up after pre-assembly.

With favorable market conditions in Canada and the United States, the sales volume at the end of 2000 was higher than expected, delaying by one month the complete build up of cement and clinker inventory before the repair shutdown, which finally started on March 15. For the erection of the cooler during the shutdown, a second engineer from IKN arrived, allowing for 24-hour supervision of the installation project.

The first seven days of shutdown were primarily used to dismantle the old cooler. At the same time, installation of the fans, some ducting, the hydraulic pack, and the electrical and control cabinets was started.

As of March 25, there were still 12 days to go before resuming the raw feed, and the Pendulum cooler installation is in line with the short schedule. The actual schedule dictates the inside of the cooler be ready for refractory installation on April 2 before firing the burners on April 5 and feeding the kiln on April 7. Between April 2 and 7, the air-tight welding of the cooler housing will be completed, as will the final adjustment of the drive cylinder and the grates.

One of the interesting features of this cooler installation is IKN's accessibility to the cooler during operation via satellite. This system allows IKN's engineer to review various operating parameters and adjust set points in case any troubleshooting or fine tuning is required.

With the high level of precision demonstrated up to now by the Ciment Quebec Inc.-IKN partnership on this project, there is no doubt that the schedule will be respected and that the equipment will perform as guaranteed.

Acknowledgment

The author wishes to acknowledge the help provided for this article by S.K. Hammi Kapoor, president of IKN-USA, and to extend his appreciation to all Ciment Quebec Inc. and IKN personnel involved in the project for their dedication to successfully win this cool race against time.

Luc Papillon is president and CEO of Ciment Quebec Inc.