Air preheating is increasing system efficiency
A new steam boiler system by Bosch Industriekessel recently went into operation at the premises of Slovenian paper manufacturer Paloma Sladkogorska. The system equipment includes the air preheating system APH, a heat recovery device which Bosch launched on the market in July this year. It reduces the flue gas temperature of the boiler by preheating the combustion air, thereby increasing system efficiency.
The air preheating system is available for single or double flame tube steam boilers with duoblock burners. It is recommended for use in applications in which process conditions mean that it would not make sense to include a flue gas condenser. On account of its special hydraulic circuitry, the system has far fewer components than commercially available two-circuit systems. It consists of a three-way valve, a combined flue gas heat exchanger and an air-side heat exchanger. If double flame tube boilers such as the one at Paloma are used, the system features two air-side heat exchangers.
A part of the hot feed water is directed to the air-side heat exchangers via the three-way valve. This preheats the combustion air for firing and reduces the temperature of the feed water. The downstream flue gas heat exchanger recovers heat from the hot boiler waste gases as a result of the cooled feed water partial flow reducing the flue gas temperature. The efficiency of the boiler system is up to two percent higher, whilst fuel consumption and emissions are lower.
The gas-fired boiler ZFR produces approximately 30 tons of steam per hour in the paper factory. An integrated superheater module on the boiler generates superheated steam instead of saturated steam, as a result of which temperatures of up to 285 degrees Celsius can be reached. The steam is required for production processes such as drying paper rolls. Every year, Paloma produces hygiene products including toilet paper, tissues, paper towels and napkins from approximately 70,000 tons of paper.
Thanks to the boiler control BCO, operation is user-friendly and settings can be tailor-made according to demand. Integrated fault messaging management, along with troubleshooting support via Bosch Teleservice, make for seamless operation.
Previously, Paloma was using a steam turbine and a 30-year-old water tube boiler. The absence of heat recovery devices meant that significant potential for savings was not being tapped into. With the new Bosch boiler system with economizer and air preheating system, the paper manufacturer now has an energy generation system at its disposal that is optimised in terms of both economic efficiency and the environment. With continuous operation, return on capital for the total investment should be seen in approximately two years. The Slovenian company C. P. Biro, a long-term partner of Bosch, was responsible for all aspects of project support locally.
The air preheating system from Bosch reduces the flue gas temperature of the boiler by preheating the combustion air.
The Bosch steam boiler ZFR with an integrated superheater module and natural gas firing systems at Paloma Sladkogorska. The air preheating system was installed in the cellar at the paper manufacturer's premises.