P22
Improvements in make-up water quality measured:
As a conclusion, the recommendations from the Danish District Heating Association can be implemented as the modern, correct way to secure optimum water chemistry, and optimize life cycles as well as reducemaintenance costs of the district heating system. The German water treatment standard for district heating, AGFW FW510, to a large extend shares conclusions with the Danish recommendations. The Danish guidelines, however, are more comprehensive and detailed i.e. concerning recommended pH- range as well as oxygen levels in the water. Case story: Aars District Heating Company Aars District Heating company produces and distributes heat and electricity (own waste-to-energy plant) for a population of 5,500 people in Northern Denmark. Distribution network of approx. 150 km. Until recently, the company used softened water and conventional chemicals to treat the water (i.e. for oxygen removal) - along with a vacuum degasser. The management then decided to implement the water treatment recommendations from the Danish District Heating Association and add installation of demineralization (RO unit) and membrane degassing for oxygen removal to the softening process. Due to this investment they are able to reduce consumption of chemicals to a minimum. The return on investment (ROI) expected to be around five years – however, the five years in fact do not take following positive factors into account: • The improved life time for the pipe distribution infrastructure etc. - which obviously is another important financial gain. • Minimized water leakages from the distribution system (due to reduced corrosion). • Improved energy efficiency (improved heat transmission in heat exchangers etc.). Case story: Hvide Sande District Heating Company Hvide Sande District Heating company is a consumer-owned district heating company for a town in Western part of Denmark (3,000 inhabitants) – including both production and distribution of heat. Distribution network of approx. 170 km – containing an amount of approx. 4,000 m3 water. Until recent investment in water treatment, the company used softened water and conventional chemicals to treat the water (i.e. for oxygen removal). The company then decided to follow the water treatment recommendations from the Danish District Heating Association and add RO for demineralization and a membrane degasser for oxygen removal. As a result, the use of chemicals almost stopped. The measurements shown below illustrates the very significant water quality improvements for both make-up water and circuit water in the distribution network. This is clearly benefitting life cycles of critical plant components as well as the pipe system in place. The new water treatment will also help prevent water leakages due to corrosion in the distribution system.
AUGUST 2016 600 10,000
MARCH 2018 4 10
Conductivity [µS/cm] Oxygen [ppb O2]
Chemical consumption reduced by more than 90%
Results measured in the distribution network (circuit water):
AUGUST 2016 561 36 16.7
MARCH 2018 220 12.2 5.9
Conductivity [µS/cm] Chloride [mg/l Cl-] Sulfate [mg/l SO42-]
The positive tendency for the measurements is that the above values keep dropping to a lower and lower level.
Membrane degassing skid for oxygen (or CO2) removal without use of chemicals.
Obviously, similar case stories from larger district heating companies also exist. However, the chosen cases serve as inspiration for district heating companies in emerging markets, where systems often are smaller initially.
For further information please contact:
SILHORKO-EUROWATER Att.: Jørn Urup Nielsen Aarhusvej 79 DK-8660 Skanderborg Denmark
Phone: +45 87 93 83 00 jni.dk@silhorko.dk
E N E R G Y A N D E N V I R O N M E N T
Made with FlippingBook Converter PDF to HTML5