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BOILER WATER

AND FEEDWATER


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- Copyright 2007 by MINGAZZINI- Parma (Italy)

BOILER WATER AND FEEDWATER GEdition 2009 - Rev.1

TABLE OF CONTENTS

Table of contentsCHAP.1

BOILER WATER AND FEEDWATER1.1 General information G-4


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Copyright 2007 by MINGAZZINI- Parma (Italy) -

BOILER WATER AND FEEDWATERGEdition 2009 - Rev.1

CHAP.1

BOILER WATER AND FEEDWATER

1.1 General information

The preparation, management, testing of feedwater for our steam boilers is extremely important to:

- reduce the risk of damage to pressurized parts

- increase thermal output

- increase availability and reliability of the system

- increase steam purity

- reduce maintenance, repair and cleaning costs

To this end, regulation UNI EN 12953-10 is useful in achieving the above objectives and is necessary to maintain

the steam boiler in the conditions required to operate the steam boiler without the continuous attendance of an ope-rator 24/7, where permitted by National Regulations.

The feedwater must be clear, with no suspended particles or impurities. The purication system must eliminate

any substances that could cause build-up of scale and of aggressive gases and must neutralize acids. The system

must be designed by a Company with experience in water treatment and, after performing the necessary tests, will

suggest the most suitable treatment method.

The steam boiler must be supplied with condensate return water and/or puried water and/or deionized/deminera-

lized water; in any case the chemical-physical characteristics of the boiler feedwater must be checked regularly, in

accordance with the instructions and tables shown below.

Some of the quality characteristics of the feedwater and of the boiler water must be improved by means of treat-

ment with chemical products.

This treatment can contribute to:

- formation of protective magnetite layers in the pressure vessel

- optimize pH value

- stabilize hardness and prevent or minimize corrosions

- achieve chemical oxygen reduction

The use of chemical products can be subjected to restrictions in some countries or for some product categories (e.g. food industry.

PRELIMINARY NOTE:

With steam boilers supplied with condensate plus demineralized water or ultrapure water by rectica-

tion (nal mixed bed) or with pure or ultrapure water only, it is prohibitedto use xed-alkali products

for chemical conditioning, in particular those that contain caustic potash and soda.

It is possible to use volatile-alkali products, with care in measuring out the correct quantity, as well as

coordinate phosphates.

Ref. Regulation UNI EN 12953-10 chap. 4 note 2


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- Copyright 2007 by MINGAZZINI- Parma (Italy)

BOILER WATER AND FEEDWATER GEdition 2009 - Rev.1

ELEMENT UNIT OF MEASURE STEAM BOILERS SUPERHEATED WATER

Pressure bar UP TO 20 bar OVER 20 bar

Clear, with no suspended solids

Ph a 25C 8,5 - 9,2 8,5 - 9,2 >7,0

Total hardness mg/l < 0,5 < 0,5


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Copyright 2007 by MINGAZZINI- Parma (Italy) -

BOILER WATER AND FEEDWATERGEdition 2009 - Rev.1

* When applying the treatment with coordinated phosphate, considering all the other values, higher concentra-

tions of P O2are acceptable.

** The organic matter is usually a mixture of many different compounds. The composition of these mixtures and

the behaviour of the single components in the operating conditions of the boiler are difcult to predict.

The organic matter can be broken down and form products that increase acid conductivity and cause corrosions

and deposits. They can lead to foaming and carryover of water with steam.

To maintain these acceptable parameters in the boiler you will need to blowdown the boiler, if possible the blow-

down should be continuous.

The concentration values in feedwater and in the boiler are connected with continuous blowdown at the following ratio:

S%= 100

S% = proportion of blowdown as a % of the water fed into the boiler.

Ca= real concentration of a given salt or ion in feedwater.

Cc = maximum concentration allowed in the boiler for the same salt.

C) If the acid conductivity of the boiler feedwater is

cap g - acqua di caldaia e alimento (ing) (02)

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