3 Water Level Control
Page 26 Mk8 MM Expansion Features Installation and Set-Up Guide 04.09.2016
3.1.3 Water Treatment
Water is a solvent, and its natural form will contain impurities that can have an unwanted effect on the
boiler operation by either corroding the metal heat transfer surfaces, or by lowering the rate of heat
transfer from the surfaces to the water. The impurities which are found in water include:
Symbol Name Effect
CaCO3 Calcium carbonate Soft scale
Ca(HCO3)2 Calcium bicarbonate Soft scale + CO2
CaSO4 Calcium sulphate Hard scale
CaCl2 Calcium chloride Corrosion
MgCO3 Magnesium carbonate Soft scale
MgSO4 Magnesium sulphate Corrosion
Mg(HCO3)2 Magnesium bicarbonate Scale, corrosion
NaCl Sodium chloride Electrolysis
Na2CO3 Sodium carbonate Alkalinity
NaHCO3 Sodium bicarbonate Priming, foaming
NaOH Sodium hydroxide Alkalinity, embrittlement
Na2SO4 Sodium sulphate Alkalinity
SiO2 Silicon dioxide Hard scale
The water treatment regime in any boiler installation has an effect on the life of the boiler. It is
important to install any level controls in accordance with the local and national authorities’ boiler
inspection bodies, approval authorities and boiler manufacturer’s guidelines. As well as this, it is vitally
important to select a suitable water level treatment regime to ensure correct and safe operation of the
Autoflame system. Water treatment companies should be able to assist with the selection and
implementation of a suitable water treatment regime.
It is important to remember that the guidelines set are limits that should not be exceeded at any time. If
these guidelines and limits are not maintained then this can cause adverse effects on equipment
installed as well reducing the longevity of the boiler and increasing ongoing maintenance
requirements.
Total dissolved solids (TDS) are impurities which have not been boiled off with the steam. If the TDS
becomes more and more concentrated in the water, bubbles and foaming will occur at the water
surface. If these solids then leave with the steam from the boiler, they can contaminate the steam plant
equipment, such as heat exchangers, steam traps and control valves. The boiler manufacturer will
specify the required TDS level in the water for that boiler. The Mk8 MM has an expansion feature
which allows the system to control the TDS level in the boiler via top blowdown control, please see
section 4 for top blowdown control.
Suspended solids will exist in the water and if the boiler water is disturbed, they will remain in this
state, however when the water is still, these solids will descend to the bottom. Over time, these solids
will build up and reduce the heat transfer, and may result in the boiler running less efficient. To reduce
this sludge which will build up at the bottom of the boiler, the Mk8 MM has a bottom blowdown
control expansion feature. Please see section 5 for bottom blowdown control.
Note: It is the responsibility of the boiler operator to ensure that the water has been
treated and maintained according to the boiler manufacturer’s specifications.
To Next Page
Loading...
Need help?
General
