Case Study: Thermal Sludge Drying
Leading Manufacturer of Thermal Sludge Drying Equipment
unhoused fan wheels of the punker D-Series
one fan wheel type for all plants
Our client is part of a group of companies from the environmental sector. In 2008, the client approached punker with the challenge of supplying suitable fan impellers for new types of modular thermal sludge drying plants that make a significant contribution to maximizing the energy efficiency of the entire plant. punker supplies highly efficient fan impellers of the Dclassic SWL series with a diameter of 1,000 mm. Flexible wheel widths do justice to the modular character of the plant and ensure optimum utilization of the motors used.
Our client is part of a stock listed group in the environmental sector. Their mission revolves around developing access to drinking water, protecting resources and ecosystems, optimizing the use of resources and producing new resources. The group’s self-declared goal is to become the worldwide leader in environmental services.
The group’s main activities include management solutions for the water cycle, recycling & waste recovery, and solutions for water treatment. Since 2008, the company has been purchasing air handling solutions from punker for its thermal sludge drying plants, which are used worldwide.
The goal of our customer was to develop thermal sludge drying plants with maximum energy efficiency. The customer approached punker with the challenge of supplying suitable fan impellers for the modularly designed plants, which make a significant contribution to the energy efficiency of the entire plant. In addition to a high static efficiency of the fan impellers, this also required exact matching of the fan impellers to the different operating points resulting from the modularity of the systems and the motors used, which were to be optimally utilized in terms of overall system efficiency.
What is thermal sludge drying?
Sewage sludge is dried to minimize its quantity and thus transport and disposal costs. Dried sludge is easy to store and handle so that it can be disposed of or recycled in a variety of ways. In addition to being used as fertilizer, dried sludge can also be used as fuel for energy production, with a calorific value comparable to that of lignite.
The limitations of mechanical sludge drying sometimes make thermal drying by water evaporation necessary. The company has developed a range of sludge drying processes that allow the sludge to be used for a variety of applications as fertilizers, by-products for composting or as fuel for incinerators.
Benefits of sludge drying:
- By removing the water from the sludge through evaporation, the volume and weight of the sludge is reduced, which facilitates storage and transport.
- Drying stabilizes the sludge, reducing odor and improving hygiene.
By evaporating the water, the final product can be used use in a composting plant. This means that the sludge can be recycled for use in agriculture.
The punker application engineers drew up a detailed requirement profile for the thermal sludge drying plant and determined backward-curved fan impellers of the R63D series (predecessor of Dclassic SWL) as the optimal air-technical solution. With a maximum static efficiency of 75%, these make a significant contribution to the energy efficiency of the entire plant, which is being used in a project for drying bio-solids in the watershed area of a large metropolitan are in the USA. With 34 wheels with a diameter of 1,000 mm and different widths, all operating ranges of the modular plant are covered and at the same time the motors used are optimally utilized. Due to the special suitability of the D-Series for free-running operation (without spiral housing), they can be flexibly used in existing box-shaped plant designs. punker supplies all fan impellers with inlet nozzles specially adapted to them, which are a prerequisite for optimum air performance.
The client’s system is a thermal sludge dryer that operates at low temperatures. While other manufacturers’ sludge dryers usually operate with hot air up to 180°C, this belt dryer requires only 90° C hot air. This low temperature requirement, the used heat recovery and the use of punker fan wheels make our client’s sludge dryers extremely energy efficient. Energy consumption is reduced, greenhouse gas emissions are lowered and odour formation is controlled by closed air circulation.
punker Dclassic SWL
With Dclassic SWL, punker offers the optimal fan wheel for unhoused applications that require a static pressure increase of 1500 to 2500 Pa | 6 to 10 in. WG (AMCA Class II). Thanks to the welded steel design, Dclassic can be used for high rotational speeds up to 75 m/s | 246 fps.
Your benefit: Very high ventilation system performance with 75 % static efficiency (83 % total efficiency) in unhoused applications.
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