The corner tube boiler is a water tube boiler with natural circulation cooling. This type of design has proven itself in the most difficult of operating conditions. The first corner tube boilers were designed for low power capacities (for lorry engines). Nowadays, corner tube boilers are manufactured for ever higher power capacities and pressures. The advantage of the corner tube design is that not only can it be used for steam generation but also for the generation of hot water, heating thermal oil, and heating or cooling other heat exchangers.
Corner tube boilers built so far
- Amount of steam: from 0.4 to 290Mg/h, no maximum capacity
- Vapour pressure: from 0.8 to 14.1Mpa; the maximum pressure is roughly 15MPa.
- Steam temperature: up to 540°C; the maximum temperature is defined by the material.
- High-temperature boilers: up to 175MW, no maximum capacity
- Thermal oil boilers: up to 30MW, no maximum capacity
- Special boilers for various chemical substances
Corner tube boilers are characterised by their robust construction and clear structure. The simple design, in particular, makes for low maintenance. The operating reliability is high due to the stable water circulation.
The boiler pressure vessel is made up of a stable, rectangularly arranged framework of downcomers, headers and distributors. The two latter components are welded to flue gas-tight tube walls, creating a closed body of tubes. It carries its own weight as well as that of all heating surfaces welded to it or separately supported by it. The load is absorbed by four downcomers in the corners and, if necessary, also by additional downcomers at the sides and transferred to the foundation.
Nearly all the pressure parts with static functions used in the ERK steam generators nearly all have the same temperature, making it easy to calculate the heat strain and to avoid associated stresses.
This means that - unlike in other boiler systems - heavy support frames are not required. Elaborate and thus expensive constructions are hardly required in the ERK systems, nor are connections to unheated elements of the framework that are susceptible to fault.
Installation of the self-supporting corner tube boiler
The self-supporting corner tube boiler is erected in such a way that it can be expanded as desired in all directions from its bearing surface. The compact tube system can be completely finished in the workshop under favourable conditions and with continuous quality control. Larger boilers can be divided into separate components and reduced to a transportable size in the workshop. Only a few pressure parts, such as the header and the distributor, are disassembled; these can be reassembled relatively easily at the final location.