New tunnel kiln with energy-saving high-efficiency burner system for ­Indonesian plant in Surabaya

In 2008, Pabrik Genteng Keramik “Good Year” in Surabaya, Indonesia, decided to build a tunnel kiln in cooperation with Keller HCW GmbH.

Pabrik Genteng Keramik, a medium-sized enterprise, has been a well-known supplier for high-quality roof tiles in Indonesia since 1956. It started its clay roofing tile production with open air drying and an old Hoffmann kiln. On account of lack of space, high fuel consumption and low productivity, a used tunnel kiln was installed in 2002. Unfortunately, this kiln did not fully meet the customer‘s requirements as it was rather susceptible to breakdown and consumed too much energy. In search of a new tunnel kiln that could provide an even temperature distribution and had a long operating life, yet assured a cost-effective and energy-saving production, Good Year came into contact with Keller HCW GmbH in Ibbenbüren (Germany).

New Keller HCW ­tunnel kiln

The new tunnel kiln concept mainly consists of three components (»1):

› Holding room for 18 kiln cars max.

› Preheater for 12 kiln cars

› Tunnel kiln with 34 kiln cars and entrance and exit sluices

Holding room

In order to avoid reabsorption of humidity by the roof tile, the kiln car loaded with wet bricks is automatically forwarded into the holding room without further delay. The holding room provides controlled climatic conditions and thus prevents the wet bricks from absorbing additional humidity that would lead to a loss of strength of the products.

Preheater

The preheater is located next to the holding room. The waste heat from the kiln heats up the preheater to approx. 120° C and lowers the residual humidity of the products to below 1%. After leaving the preheater, the kiln car automatically enters the entrance sluice of the kiln.

Tunnel kiln

This is a traditionally built kiln that begins and ends with a sluice to keep the pressure conditions in the kiln at an even level during kiln car pushing.

The use of crown jets provides good temperature distribution in the heating-up zone (»2). With these crown jets, a small amount of preheated air is blown with high pressure against the flue gas flow above the setting. The encountered resistance renders the flue gas flow through the setting more intense and thus, at an early stage, initiates an even temperature distribution across the firing channel section.

The fully automatic burner plant (»3) starts with flame-controlled burners, developed by Keller HCW, followed by an injector burner plant working in full load and partial load. The control mechanism for the burners assures a targeted introduction of the gas/air mixture either into the upper or lower area of the firing channel and the continuous alternation between short flame and long flame ensures a smooth and even heating-up of the roof tiles. A uniform brick-red colour across the whole kiln setting is the result of the very good temperature distribution (»4).

Thanks to the special design of the insulation of the walls and of the kiln ceiling with an interlocking system and the energy-saving tunnel kiln car superstructure (»5), the fuel consumption of the kiln could be reduced considerably, and in the end the already expected low energy consumption proved to be even lower.

Together with the construction of the tunnel kiln, a hot air pipe was installed to lead to the existing, formerly stand-alone chamber dryer. The interconnection between kiln and dryer feeds excess warm air from the cooling area into the existing drying chambers where it is re-used to dry the roof tiles. This additional feature helped to save energy costs amounting to several hundred thousands of euros.

The Siemens Simatic S7 control system assures smooth operation of the fully automatic tunnel kiln.

The Keller HCW Teleservice System allows control of the kiln from a home office or from other production sites (»6) and, in an emergency, ensures fast troubleshooting in the production process.

In cooperation with many regional suppliers for steel and pipeline construction and masonry and insulation work, Keller HCW and its strong local partners succeeded in building a modern and cost-effective tunnel kiln.