Low temperature drying: a case study

1 Thermal drying cost distribution

2 Flow chart of the STC thermal drying process

3 Humid sludge silos

4 Heat exchanger

5 Hot water pipes feeding both dryers

6 Dryer

7 Return module, the sludge falls from the upper belt to the lower belt and is returned to the beginning of the tunnel

8 Integration in a cement plant in Alicante/Spain

9 STC dryer – cement factory integrated system (Alicante, Spain)

Energy efficient drying of sewage sludge

Incorporating waste treatment processes in systems in which residual energy can be utilized is one of the best residue management alternatives. With an LHV of between 2000 and 4500 kcal/kg, efficiently dried sewage sludge can be used as standard fuel, thereby reducing primary energy consumption and the CO₂ quota.

1 Introduction

The emission reduction requirements established by the Kyoto Protocol pose an enormous challenge for the industrial world, and most particularly for the main industrial consumers of fossil fuels, such as, for example, the cement industry. In this type of industry, fuel costs exceed 30 % of production costs. Consequently, for several years now, most of these industries have started implementing energy optimisation measures in their processes. To date, strategies have been based on the search for alternative fuels – classified as substitute fuels, e. g. sewage waste [1] and...