Corner tube boiler

A Eckrohrkessel is a special kind of a natural circulation boiler, which differs from other water -tube boilers by its characteristic water - steam cycle. A separation of the water-steam mixture is already taking place outside of the drum.

Principle

Eckrohrkessel have been developed for small steam capacities. The boilers were two important design criteria based. Firstly, a stable water circulation should ensure that all heated risers are cooled sufficiently even at low partial loads. Secondly, emphasis was placed on a self-supporting shell construction. This manifests itself in the self-supporting monocoque construction, ie the non-heated drum down pipes and return pipes (which are not connected to the drum downpipes ) that are in the corners of the boiler, which form the scaffold, hence the name Eckrohrkessel.

Moreover, the pipe system is also responsible for managing the distribution of water in the riser pipe and fall pipe, to collect the steam-water mixture, and a certain amount of to make separation from the steam-water mixture. Thus, the circulation of water takes place at the same time through the drum and through the return pipes in the piping system.

History

During the Second World War and especially towards the end, there was in Germany a lack of fuels such as gasoline and diesel. However, the demand for fuels to rise. Henrich preemption developed a solution to this problem by designing the concept of a new boiler type, which could satisfy the demand with alternative fuels such as wood,. In 1944, the first developed by Henrich preemption Eckrohrkessel was installed on a truck.

Effect

The water flows from the drum through the downspouts in the distributor where it is distributed in the different risers. The steam -water mixture circulates ( in the heated by radiation area ) by the pre-separator (also known as Cross - collector called ) where the separated steam flows through overflow pipes to the drum and the steam-water mixture flows through the collector to the drum. The residual amount of water flows through the return line into the back wall manifold which is directly connected to the longitudinal distribution, and thus back to the riser where it is then heated.

The water flows from the unheated drum downspouts to the Distributor page, as well as the back wall distributor and supplies the heated riser pipes with water. The collector is connected through the overflow already a separation of the water - steam mixture instead. Part of the water flows from the collector through the so-called downcomers back downward while the remainder of the water-steam mixture flows through the collector to the drum.

Benefits

• The boiler extends from the fixed point in all directions, and thus adapts to the different operating conditions, without additional stresses or imperviousness to notches, ie, the boiler can expand without problems in vertical direction.
• The shorter waterways to supply the riser tubes allow for quick adjustments to the driving style of the boiler at part loads.
• By the system of the return pipes, the heating surfaces can be provided not only on the drum with water. The heating surfaces can thus be relatively far away from the drum. Large boiler, as is common in waste incineration plants, so can be implemented without much effort.
• The permissible temperature gradient can thus be significantly higher, allowing a rapid motion of the vessel. The wall thickness of the drum throughout the circumference may be constant, whereby the deformation of the drum is low.
• It can be connected to the drum relatively little tubes, so there is no weakening of the material and the drum throughout the circumference can be carried out with the same wall thickness.
• Low risk of foaming. Since the water and the steam -water mixture that is passed into the drum keeps the same constant level all the time the space above the water level leaves the drum.
• The case flow and return pipes have a diameter so large that vapor bubbles do not endanger the circulation at high pressure drops or load change speeds.
• Low pressure fluctuations during load changes.
• Load fluctuations in the shortest time possible, without the vapor pressure changed significantly. Even with load fluctuations of the water level remains quieter than other types of boilers in the drum.

Disadvantages

• Bad feed water with high salt concentrations, eg, magnesium, calcium, etc. can lead to salting out, causing the boiler tubes can prevail.
• The design and the design concept of the boiler is complex and thus expensive.

Fuels

The most common fuels that are burned in Europe, America and the Pacific region are: bagasse, biomass, lignite, coal, bark, natural gas, industrial waste, Khuff gas MFO, marine fuel oil, Organic materials, oil, litter, rice husks, rubber tree, sludges, wood, wood chips, municipal waste, hazardous waste.