Research and Development of Heat Exchanger 'Water-Sludge'

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en

Heat exchanger 'water-sludge' (screw type heat exchanger) is mainly used for indirect sludge preheating at waste water treatment plants. Preheated sludge is pipelined into the digestion tanks, where anaerobic stabilisation is under way. A similar heat exchanger ''flue gas-sludge'' is being developed for the purpose of utilizing the available heat coming from sludge incineration. Principal advantages of this design are as follows: low energy consumption for sludge transport and easy access to the sludge side. The aim of this study is to describe the creation of a mathematical model of a heat exchanger, which will be used to monitor the influence of temperature on dewatering of mixed raw sludge. For this specific task a made-to-measure heat exchanger had to be designed. From the possible choices, a helical plate heat exchanger was chosen. The advantage of this type of an exchanger is a small built-up area, a high heat transfer area and easy maintenance and cleaning on the side of the sludge. Another advantage is a helical flow, which has a positive effect on self cleaning abilities. However, pressure losses would be higher than at direct (straight) canals. The increase of pressure loss is accompanied by an increased coefficient of heat exchange a. After the design of the exchanger measurements from a pilot unit would be obtained. On the base of them, the relations will be revised, if required. If sludge preheating shows to be advantageous for dewatering an exchanger of a ''fuel gas-sludge'' type would be designed in the next phase.

heat exchanger, sludge, heating

2006-08-27

Process Engineering Publisher

Praha

80-86059-45-6

Chisa 2006 – Summaries 4 – System engineering

P5.116–

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