Why the Foundry Lößnitz has invested in Modern Filter Technology
Although sand and gravity die casting are known to release large quantities of particles and tertiary amines, there is a lack of solutions for efficient and economic separation of these emissions. Despite the difficult situation, a German foundry began implementing an exhaust air purification project to optimally protect employees, local residents and the environment.
The Lößnitz foundry produces many tons of tools for Porsche toolmaking and for vehicles of BMW, Daimler, Volkswagen, etc. This makes the traditional company an important employer in the region. But its position in the middle of the city had reached a breakpoint.
When casting the huge tools, the filler from the large moulds evaporates, giving rise to a high air load of particulate matter, soot and odours. In the past, this had led to tensions in the neighbourhood of the factory. The measurements of the Saxony State Office for Environment, Agriculture and Geology showed two years ago that the foundry caused a markedly increased environmental impact on days on which it operated. Although these were not deemed serious, measures were called for.
In 2014, the company took the decision to increase production capacity - while simultaneously comprehensively redeveloping the casting hall. A new filter technology for the filtration of large amounts of particulate matter needed to be installed, and, additionally investments needed to be made in the elimination of gas emissions and unpleasant odours.
As a first step, the hall was sealed. As a result, emissions could no longer diffuse through openings. Likewise, investments were made in modern environmental filter technology and in the optimum supply of clean fresh air to the employees working in the hall. The heat for the temperature control of the supply air is recovered from the excess heat of the furnaces in the heating period.
First Challenge: Sand and Gravity Casting Releases Emissions
Sand and gravity casting release large quantities of particulate matter and tertiary amines. To date, solutions for the efficient and economic separation of these emissions lacked. Despite the difficult situation, Gießerei Lößnitz GmbH began to implement an exhaust air purification project to optimally protect employees, residents of the neighbourhood, and the environment.
Together with Kappa, a system has been developed that efficiently and economically separates both emission types - fine dust and odours.
The core area of the plant is a Kappa de-dust collection system, which represents a completely new filter system for the separation of industrial dusts. The so-called Kappa Ekon requires only half as much space as conventional systems and reduces the residual dust content by half and energy consumption by one third.
Second Challenge: Moulds Distributed throughout the Hall
The main problem was that there is no permanent place in the workshop for casting from which exhaust fumes could be extracted. The huge moulds are distributed throughout the hall, with the exhaust air collecting under the roof. Whenever a skylight is opened, the vapours escape.
The system developed by Kappa will, in the future, collect the exhaust gases directly beneath the hall roof. For this purpose, 17 extraction points have been set up, which circulate a total of 180,000 cubic metres of air per hour. Sensors detect where in the hall casting is being performed, and performance is automatically optimized in the required places.
The emission-loaded hall air is replaced by fresh air. It is preheated to the desired temperature, and diffuses draught-free along the hall floor. "Due to this, there are no draughts, and the workstations are provided with pleasant atmospheres for the workers," says Raphael Mülleder, process engineer at Kappa, who co-developed the system. The system continuously supplies the workers with fresh air, meaning windows and doors can remain closed. The supply air is heated via the recovered excess heat from the existing smelting furnace.
The Results with the Filter System
Thanks to the innovative environmental technology, the expansion of operations was permitted. Now the fine dust values in the exhaust air flow are more than tenfold lower and the odour emissions fall below the limit values. Last but not least, the new system reduced energy consumption by around 32 % compared with conventional solutions.
This case study was first published by Kappa Filter Systems GmbH.
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