Scaling in domestic heating equipment: getting to know a complex phenomenon

2004 ◽  
Vol 49 (2) ◽  
pp. 129-136 ◽  
Author(s):  
H. Brink ◽  
P.G.G. Slaats ◽  
M.W.M. van Eekeren
Keyword(s):  
Drinking Water ◽  
Calcium Carbonate ◽  
Saturation Index ◽  
Carbonate Precipitation ◽  
Heating Equipment ◽  
Calcium Carbonate Precipitation ◽  
Domestic Heating ◽  
Scaling Properties ◽  
Langelier Saturation Index ◽  
Water Companies

Excessive scaling is one of the main nuisances in relation to the use of drinking water. Ever more water companies try to minimise scaling. Although scaling is an old problem, prediction of scaling has been proven to be very tricky. Traditionally, the (Langelier) Saturation Index is used to evaluate scaling properties of drinking water. From experience it is well known that this parameter is not suitable for proper prediction. New parameters have been developed and standardised for scaling prediction, namely the Calcium Carbonate Precipitation Potential, calculated at a temperature of 90°C (CCPP90); the Saturation Index, also calculated at a temperature of 90°C (SI90); the Nucleation Index (NI) and the Measured Calcium Carbonate Precipitation (MCCP). These parameters are currently successfully used in The Netherlands. The development of new parameters to predict scaling in domestic heating equipment has resulted in a better understanding of processes involved. Even now unexpected and at first sight contradictory results are obtained frequently. With the use of the developed measuring techniques, solutions may be found to combat excessive scaling.

scholarly journals Assessment of calculation methods for calcium carbonate saturation in drinking water for DIN 38404-10 compliance

2013 ◽  
Vol 6 (2) ◽  
pp. 115-124 ◽  
Author(s):  
P. J. de Moel ◽  
A. W. C. van der Helm ◽  
M. van Rijn ◽  
J. C. van Dijk ◽  
W. G. J. van der Meer
Keyword(s):  
Drinking Water ◽  
Calcium Carbonate ◽  
Saturation Index ◽  
Computer Programs ◽  
Maximum Temperature ◽  
Chemical Databases ◽  
Calcium Carbonate Precipitation ◽  
Chemical Modeling ◽  
Practical Applications ◽  
Chemical Database

Abstract. The new German standard on the calculation of calcite saturation in drinking water, DIN 38404-10, 2012 (DIN), marks a change in drinking water standardization from using simplified equations applicable for nomographs and simple calculators to using extensive chemical modeling requiring computer programs. The standard outlines the chemical modeling and presents a dataset with 10 water samples for validating used computer programs. The DIN standard, as well as the Standard Methods 2330 (SM) and NEN 6533 (NEN) for calculation of calcium carbonate saturation in drinking water were translated into chemical databases for use in PHREEQC (USGS, 2013). This novel approach gave the possibility to compare the calculations as defined in the standards with calculations using widely used chemical databases provided with PHREEQC. From this research it is concluded that the computer program PHREEQC with the developed chemical database din38404-10_2012.dat complies with the DIN standard for calculating Saturation Index (SI) and Calcite Dissolution Capacity (Calcitlösekapazität) or Calcium Carbonate Precipitation Potential (CCPP). This compliance is achieved by assuming equal values for molarity as used in DIN (obsolete) and molality as used in PHREEQC. From comparison with widely used chemical databases it is concluded that the use of molarity limits the use of DIN to a maximum temperature of 45 °C. For current practical applications in water treatment and drinking water applications, the PHREEQC database stimela.dat was developed within the Stimela platform of Delft University of Technology. This database is an extension of the chemical database phreeqc.dat and thus in compliance with SM. The database stimela.dat is also applicable for hot and boiling water, which is important in drinking water supply with regard to scaling of calcium carbonate in in-house drinking water practices. SM and NEN proved to be not accurate enough to comply with DIN, because of their simplifications. The differences in calculation results for DIN, SM and NEN illustrate the need for international unification of the standard for calcium carbonate saturation in drinking water.

scholarly journals Assessment of calculation methods for calcium carbonate saturation in drinking water for DIN 38404-10 compliance

2013 ◽  
Vol 6 (2) ◽  
pp. 167-198
Author(s):  
P. J. de Moel ◽  
A. W. C. van der Helm ◽  
M. van Rijn ◽  
J. C. van Dijk ◽  
W. G. J. van der Meer
Keyword(s):  
Drinking Water ◽  
Calcium Carbonate ◽  
Saturation Index ◽  
Computer Programs ◽  
Maximum Temperature ◽  
Chemical Databases ◽  
Calcium Carbonate Precipitation ◽  
Standard Methods ◽  
Practical Applications ◽  
Chemical Database

Abstract. The new German standard for calcium carbonate saturation in drinking water, DIN 38404-10, 2012 (DIN), marks a change in drinking water standardization from using simplified equations applicable for nomographs and simple calculators to using extensive chemical modeling requiring computer programs. The standard specifies the chemical outlines for the modeling and presents a dataset with 10 water samples for validating used computer programs. The DIN standard, as well as the Standard Methods 2330 (SM) and NEN 6533 (NEN) for calculation of calcium carbonate saturation in drinking water were translated into chemical databases for use in PHREEQC (USGS, 2013). This novel approach gave the possibility to compare the calculations as defined in the standards and internationally accepted chemical databases provided with PHREEQC. From the research it is concluded that the computer program PHREEQC with the developed chemical database din38404-10_2012.dat complies with the DIN standard for calculating Saturation Index (SI) and Calcite Dissolution Capacity (Calcitlösekapazität) or Calcium Carbonate Precipitation Potential (CCPP). This compliance is achieved by assuming equal values for molarity as used in DIN (obsolete) and molality as used in PHREEQC. From comparison with internationally accepted chemical databases it is concluded that the use of molarity limits the use of DIN to a maximum temperature of 45 °C. For current practical applications in water treatment and drinking water applications, the PHREEQC database stimela.dat was developed within the Stimela platform of Delft University of Technology. This database is an extension of the internationally accepted chemical database phreeqc.dat and thus in compliance with Standard Methods 2330. The database stimela.dat is also applicable for hot and boiling water, which is important in drinking water supply with regard to scaling of calcium carbonate in in-house drinking water practices. The SM and NEN proved to be not accurate enough to comply with DIN, because of their simplifications. The differences in calculation results for DIN, SM and NEN illustrate the need for international unification of the standard for calcium carbonate saturation in drinking water.

scholarly journals Procedure for Calculating the Calcium Carbonate Precipitation Potential (CCPP) in Drinking Water Supply: Importance of Temperature, Ionic Species and Open/Closed System

Water ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 42
Author(s):  
Camilla Tang ◽  
Berit Godskesen ◽  
Henrik Aktor ◽  
Marlies van Rijn ◽  
John B. Kristensen ◽  
...  
Keyword(s):  
Drinking Water ◽  
Calcium Carbonate ◽  
Open Source Software ◽  
Open Systems ◽  
Ionic Species ◽  
Water Systems ◽  
Carbonate Precipitation ◽  
Calcium Carbonate Precipitation ◽  
Closed Systems ◽  
Drinking Water Systems

The calcium carbonate (CaCO3) precipitation potential (CCPP) can predict the potential for corrosion and lime scaling in drinking water systems. CCPP can be calculated by different standards, but none of these consider all of the conditions in drinking water systems where temperatures can reach 100 °C and the water exchanges CO2 with the atmosphere. We provided and demonstrated a procedure for CCPP calculations using the open-source software PHREEQC with the phreeqc.dat database at temperatures relevant for drinking water systems (10–90 °C) and for open systems in equilibrium with atmospheric CO2. CCPP increased by 0.17–1.51 mmol/kg when the temperature was increased from 10 °C to 90 °C and increased by 0.22–2.82 mmol/kg when going from closed to open systems at 10 °C. Thus, CaCO3 precipitation may be underestimated if CCPP is only considered for the lower sample temperature and for closed systems. On the other hand, CCPP10 decreased by 0.006–0.173 mmol/kg when including the ionic species from the German DIN 38404-10 standard in addition to calcium, alkalinity and pH, indicating that all relevant ionic species should be included in CCPP calculations. CCPP values should always be reported with the calculation procedure and temperature to avoid inconsistency in literature.

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