IKN Pendulum Cooler

3 Years Experience with an IKN Pendulum Cooler at Union Cement Company, Ras Al Khaima, United Arab Emirates By Tor Gautestad, Works Manager, Union Cement Company Mirko Koehler, IKN GmbH Introduction In the North of the Emirate of Ras Al Khaimah, UAE large limestone deposits are found. The limestone mountains rise from the sea up to an altitude of 2087 m. They extend from the outside of Ras Al Khaimah town to the picturesque Musandan peninsula directly at the straight of Hormuz. High quality limestone is exported, even as far as Australia, and four Cement Producers utilize this resource, including one White Cement Producer. Union Cement Company (UCC) was the first Cement Company established in the United Arab Emirates in 1972. UCC is a publicly listed company; its shareholders include the Government of Ras Al Khaimah as well as private entities. Production started in 1975 with two long dry kiln lines by IHI, Japan each with a rated capacity of 725 t/d. A third line with a 4 stage pre-heater, pre-calciner kiln and an initial capacity of 1500 t/d was built in 1979 as well by IHI. Since the start of operations, the management of UCC was contracted to Scancem now part of by Heidelberg Cement.

Fig. 1: UCC Cement Works, Line #3

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Upgrading of Line #3: The gradual increase in cement demand in the UAE required higher clinker outputs. Part of the necessary plant improvements was the upgrading of kiln line #3. The capacity of line #3 was gradually increased to 1,800 t/d and the existing conventional clinker cooler became the bottleneck of the pyro line. Originally design features of the existing conventional Cooler: • • • • • • •

Capacity: Aerated grate area: Grate loading: Crusher: Spillage transport: Installed Cooling air: Housing width:

1,500 t/d 48 m² 31.25 t/m²*d Hammer Crusher Internal Drag Chain 3.5 Nm³/kg 4.2 m

Fig. 2: Backend of the existing clinker cooler

Limitations of the Babcock Hitachi Cooler: • • • • •

High maintenance requirements due to frequent grate plate changes Production loss due to frequent unscheduled cooler stops Low cooler efficiency High maintenance and operational cost on the down stream gravel bed filter due to high dust load and exhaust air amount High clinker outlet temperature of 160 - 180 °C Page 2 / 11

In view of the need to overcome these limitations together with the envisaged capacity increase above nominal by almost 50 % to 2,200 t/d UCC decided in 2001 to replace the clinker cooler. The result of the evaluation process by UCC was the selection of the IKN Pendulum Cooler, to be installed into the existing housing. The clinker transport system had sufficient reserves and could be reused. IKN’s design work had to focus on fitting the pendulum grate into the limits of the existing cooler housing without moving the discharge point to the clinker conveyor. The features of the IKN scope of supply included •

KIDS: The fixed inlet spreads the clinker over the entire width of the following grate and prepares the clinker bed for best air permeability by lifting the fines to the bed surface.

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Pendulum grate: The grate area consists of Coanda nozzles, generating horizontal air jets for an air saturated clinker bed resulting in high efficiency and low clinker exit temperature. The suspension of the movable grate structure realized with the patented IKN wear free pendulum suspension.

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Single grate drive with Hydraulic Power Pack: The movable grate section is driven by one hydraulic cylinder located underneath the fixed inlet. The hydraulic power pack consists of two pumps with motors, of 22 kW each, where one pump is in operation with the second pump is a back-up unit. The system is designed for a maximum grate speed of 15 spm while the speed at full production is only 9 spm. The sizing of the pump benefits of the high transport efficiency of the suspended IKN grate above 80%. At the UCC plant, this results in a power requirement for the clinker transport on the grate of 0.21 kWh/tclinker.

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Roll Crusher: The roll crusher is located at the cold end of the cooler with a roller speed of 5 rpm. Each roll is driven by an electric gear motor with 11 kW. Compared to the existing hammer crusher, operationally security is gained, since large lumps will not cause blockages or crusher overloads. Furthermore, the dust load in the exhaust air is reduced as well as the maintenance costs. Due to the low rate of wear, the crushing rings match the service life of the grate surface. Refacing of the crushing edges on the rings is possible.

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PHD (pneumatic hopper drainage) The existing internal drag chain was replaced. IKN installed a new compartment floor and added 14 discharge points, each equipped with one PHD unit. Clinker fall through is limited in size and amount and removal is realized by pneumatic conveying. Compared with an internal drag chain a better sealing of the under grate compartments is achieved. Conveying air for the PHD is supplied by cooling fan #2 at an operational pressure of approx. 80 mbar. No additional equipment is required.

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Heat Shield The hydraulically driven heat shield is located at row #22 (neutral point at row #19). It separates the bright hot zone of the cooler from the cold back end. Losses due to radiation will be minimized and the cooler and kiln process is stabilized.

Fig. 3: Cross section of the Pendulum Cooler

Design features of the Pendulum Cooler: Throughput: Grate width: Grate length: Aerated surface: Grate loading: Installed fans: Crusher: Installed cooling air: Clinker outlet Temperature: Kiln heat consumption: Cooler efficiency:

2200 t/d 3.0 m KIDS 7 rows Grate 44 rows 48.7 m² 45.2 t/m² day 6 pcs, 2 existing fans reused, 4 new fans Roll Crusher, 3 rolls, 11 kW each, 3.0 m wide 2.00 Nm³/kg clinker 65°C + Ambient 860 kcal/kg 74.5 %

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Erection In August 2002, the project was executed turnkey whereby the local erection was carried out with a Dubai based contractor Petron. The demolition of the original cooler internals, civil works; mechanical and electrical erection together with the refractory work and cold commissioning took place within a timeframe of 32 days (flame off to flame on).

Fig. 4: Extension of housing and preparation of roll crusher support

Fig. 5: New mobile frame in the existing Cooler housing

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Cooler Operation The cooler went into operation without problems and nominal production of 2100 was reached within days. Right from the start-up there was no doubt about te increase in production rate of the kiln line. The convincing performance figures are still maintained today as shown in table 2. The grate is operated at a speed of 9 spm which results in continuous operation with a clinker bed depth of 550 mm. Further increase in bed depth is restricted by the high portion of fines in the clinker (40 % < 4mm), which limits a uniform air distribution at deeper bed depths. The performance figures are summarized in table 2. During the first year of operation, the cooler experienced one unscheduled stop of 3 hours which was caused by a malfunction of a motorized inlet vane damper of a compartment cooling fan. Since this has been the only unscheduled shutdown since start-up in 2002, the cooler availability is above benchmark at > 99 %. It is worth mentioning that the project goal of decreased dust emission was achieved through the significant decrease in exhaust air volume and increased stability in cooler operation. Additionally, the reduced dust generation within roll crusher lowered the dust load to the gravel bed filter and hence increasing the availability of the filter in line with the cooler. The replacement of the gravel bed filter with a new bag filter, as planned earlier, was therefore not required anymore.

Kiln Throughput Grate Loading Outlet Clinker Temperature Cooling air Tertiary air Temperature Secondary air Temperature Cooler efficiency Kiln heat consumption Vent air Temperature

[t/d] [t/m2*d] [°C a.A.] [Nm³/kg] [°C] [°C] [%] [kcal/kg] [°C]

Before After Modification Commissioning October 02 1800 2130 36.7 43.8 148 85 2.50 1.80 758 935 861 1007 65.1 77.0 915 858 225 255

Table 2: History of cooler performance

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After 3 years September 05 2000 41.0 65 2.00 941 1008 75.5 860 234

Maintenance In addition to the high cooler availability, UCC reports that the maintenance requirements are greatly below the anticipated budget. The main benefit is attributed to the long wear life of the Conada nozzles. During the first three years of operation, the cooler grate surface did not require maintenance. The blades of the Coanda Nozzles still show all four wear indicators as shown in the close up below. Minor maintenance work was required for the scheduled re-facing of the crusher rolls. This could be performed by the in-house maintenance team through hard facing of the rings, which work is scheduled within a two year intervals. Until now, zero (!) maintenance expenses have been recorded for the grate surface, hydraulic power pack, cooling fans and PHD system. This is a remarkable result that contributes greatly to the low operating cost of the cooler.

Fig.6: Grate surface in September 2005 after 3 years operation; General view and close up

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Fig. 7: KIDS in September 2005 showing no wear after 3 year operation

Economic Outlook The investment activity of the cement producers in the Gulf region on the one hand is fueled by an optimistic demand outlook, and, on the other hand, is still influenced by past experience, since regional growth rates are still linked to the level of oil prices. Based on this background, UCC recognized the need for new production capacity and towards the end of 2004 decided to install a new production line with lowest possible production cost to ensure long term viability of the project past the present building boom. The new kiln line has a capacity of 10,000 t/d. Project responsibility is with CBMEC from China, building on the most modern and efficient components of their project partners.

10,000 t/d IKN Pendulum Cooler for line #4 The very good results of the IKN Pendulum Cooler of line #3 at UCC and the positive experience of IKN with large capacity coolers in Korea and Thailand led to the logical decision to select an IKN cooler for line 4.

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Line #4 Cooler Design: Grate width: Grate length: Aerated surface: Grate loading: Installed fans: Crusher: Installed cooling air: Clinker outlet Temperature: Kiln heat consumption: Cooler efficiency:

6.8 m KIDS 10 rows Grate 95 rows 229 m² 43.9 t/m² day 12 pcs Roll Crusher, 6 rolls, 15 kW each, 4.8 m wide 1.95 Nm³/kg clinker 65°C + Ambient 720 kcal/kg 74.5 %

Fig. 8: IKN’s 10,000 t/d Pendulum Cooler at UCC Kiln #4

Line 4 is now under construction and the installation of the IKN clinker cooler is scheduled to start early 2006 with commissioning in September 2006. In comparison to the cooler of line 3, the 10,000 t/d cooler has one central drive point consisting of two hydraulic cylinders. They will be installed underneath the fixed inlet, which makes them accessible during operation. The size of entire line requires a tertiary take-off from the cooler housing, which will be realized with two separate tertiary air ducts in order to achieve low secondary and tertiary air velocities together with a low dust return rate. The IKN Pendulum Cooler selected for the 10,000 t/d new line of Union Cement will be the largest clinker line in operation in the Middle East.

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Design Features of the 10,000 t/d cooler Wear parts such as the Coanda nozzles will be interchangeable with the existing IKN cooler of line #3. However, the following technical improvements - developed by IKN since 2002 – are included in the design of the new 10,000 t/d cooler. 1. Linear Pendulum System The Linear Pendulum System (LPS) enables a quasi linear movement of the mobile rows while keeping the advantage of the maintenance free pendulum suspension. The LPS is integrated in the cooler housing for easy installation.

Fig. 9: LPS System installed in the Cooler Housing

2. Coanda nozzles with Mini Blades Mini Blades create more openings in the grate surface into the clinker bed for a finer and more uniform aeration, resulting in improved efficiency and clinker cooling.

Fig. 10: IKN Mini Blades with 9 Slots

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Conclusion The IKN Pendulum Cooler installed in 2002 at Union Cement line #3 has successfully been in operation for more than 3 years with 99.99% availability and lowest overall maintenance. Based on these results and confirmed by positive reports from customers of large kiln lines in Korea and Thailand, UCC decided in favor of IKN for the new clinker production line. The new cooler will come into operation in September 2006. The outstanding operating results and lowest operating costs of the IKN coolers in operation have made IKN the natural choice for many of the new kiln lines in the Middle East. For the projects in the Arabian Peninsula currently under construction or design, the IKN Pendulum Cooler has a market share of more than 50 % at the time of writing this paper, having been selected in 7 of the last 12 projects awarded.

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