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Great safety for great projects: Valve systems for energy generation

Process valves are at home in the entire process of energy production, in all types of power plants and in all spheres of industrial process steam technology. A multitude of individual valves control the compressed air and gas feed, ensure that turbines and conduits are rinsed at regular intervals, conduct steam and liquid media of all kinds and clean filter systems with short, but strong jets of compressed air. If these individual valves are combined to form systems, and this is what Buschjost does, a wide variety of advantages arises.

The operation of large-scale steam generators and power plants is essentially dependent on the reliability of the individual components. In order for these to function safely, on the one hand in all industrial countries extensive regulations and standards have been enacted, for example explosion protection regulations, pressure tank ordinances and electrical installation regulations. On the other hand, component manufacturers are constantly working on optimising and improving products. Buschjost, for example, has completely redeveloped or revised its valve platform for power plant and process technology with the Click-on® platform and the flanged valve series. In so doing the company from Bad Oeynhausen benefited from the many years of experience of HERION, the valve specialists. Buschjost has become successor to HERION as specialists for power plant valves within the IMI Norgren Group.

Furthermore, some members of the Norgren Group – Buschjost, FAS, KIP and Kloehn – have concentrated their competences and given birth to the Norgren Fluid Controls Division within Norgren. Together the four companies cover the entire spectrum of applications of solenoid and process valves, pumps and fluid technology solutions and are hence in a position to offer any conceivable solution to customers worldwide from a single source, quasi as full-line providers.

Over 100 of the 900 employees of the new Group are experienced engineers and developers who represent an enormous amount of skilled potential, being competent in customer-specific system solutions ranging from medical technology and mechanical and plant engineering all the way through to heating and air-conditioning for vehicles. The cooperation between the four development departments can already refer to first results. For example, an FAS miniature valve assumes the control of an air-controlled Buschjost valve.

Today Buschjost provides the market with a comprehensive range of modern process valves for the low pressure range up to 40 bars. They are used in steam technology, flue-gas desulphurization and for water, gas and filter technology. Owing to the high requirements in this field, for these applications Buschjost offers piston valves with a high safety reserve and which are also available in a back-pressure safe version. This feature is crucial for safe operation in such applications as generator cooling.

State-of-the-art, pioneering valves for process and energy technology distinguish themselves from the time-tested type series in a number of points. They have a longer service life and require less maintenance and are tailored precisely for their specific use. At the same time the valves must be economical. This formed the basis for the valve system technology. With the Click-on® system the company from Bad Oeynhausen has laid the foundation stone for a comprehensive valve system. Buschjost has optimised the Click-on® type series so that it can make do with just a few types of magnets. These ensure that the piston valves function reliably in rated widths ranging from DN 15 to DN 150 and G 1/4 to G 2.

Special attention was paid to optimising the valve bodies when developing the new valves. All relevant parameters were analysed very exactly beforehand using state-of-the-art design and simulation tools. The results express themselves among other things in optimised flow rates and valve geometries. Besides, it was possible to significantly reduce the number of individual parts in each valve by integrating and concentrating functions to raise the length of service life and minimise maintenance work.

Owing to their compact pistons, the piston valves are very flat. To make them unsusceptible to contamination, the developers have positioned the sliding surfaces of the pistons outside the through-flow area. This design minimises both susceptibility to contaminated media and has a positive effect on operating life. Pistons with very smooth roller-burnished surfaces are used in the valves of the new type series, again reducing wear. Depending on the type series, valves made from brass or cast steel and stainless steel housings are in the range. In the superheated steam version, they can be used for media up to a temperature of +200 degrees Celsius. Special developments for temperatures down to -40 degrees or pressures up to 70 bars complement the programme as do valves that work without grease for installation in oxygen-carrying systems.

Comprehensive investigations of the old, flanged type series show that they contain up to 25% of steel and/or stainless steel which has no immediate function and does not affect the strength and stability of the housing; its only impact is on the weight. Optimisation means intervening at the right points and improving. All of the dimensional and wiring diagrams comply 100% with the relevant DIN and ANSI standards. In addition to this the relevant fitting dimensions are retained so that the seals and accessories continue to fit. A DN 50 valve of the new generation is around 3.5 kilograms lighter than conventional flanged valves; this is equivalent to an approximately 25% saving in weight. This makes them significantly easier and faster to install and faster to remove for maintenance or repair.

All of the functions and parameters have been backed up and checked via elaborate simulations on the computer. The valves comply with the specifications for group 2 gases of the Directive concerning pressure equipment. Safety aspects were given top priority in the designing process. Items such as strength determination and load factor are gaining in importance. Therefore, Buschjost has subjected the materials for the valve housings to a critical assessment. Only some of the requirements imposed on durable fittings can be met by the grey cast iron which has been the standard material to date. Buschjost has therefore decided to use only cast steel and stainless steel for the new flanged valve type series. In spite of high quality cast steel, the prices remain unchanged. Particularly in the process industry and energy technology, standard versions soon come up against their limitations. The plants require electric movement indicators, manual emergency overrides, versions with special plug-in connectors, manual actuation etc. The right solution for almost all requirements is to be found in the comprehensive range of accessories. 

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