DE1810424A1 - Preparations for cleaning boilers on the combustion side - Google Patents

Description

Dr. F. Zumsfein - Dr. E. Assmann 1810424

Dr, R. Koenigsberger

Case 3/78 Dipl. Phys. R. Hobbauer

Dr.Cr/fu. Patent attorneys

Munich 2, Bräuhausstrafje 4 / lH

CH. BOEHRINGER 50HN, Ingelheim am Rhein

Agent for cleaning boilers on the combustion side Λ

The invention relates to a new means for cleaning boilers on the furnace side.

As is well known, form inside the boiler of heating boilers Solid residues from the fuels (e.g. coal, coke or oil), partly from soot and tar, partly from non-combustible, inorganic There are ash residues. Such deposits build up in the form of firmly adhering deposits on the boiler walls or the heat exchanger elements and hinder the heat transfer due to their strong thermal insulation properties. They also lead (due to the content of inorganic ash residues, e.g. acidic sulfur compounds) also to signs of corrosion on the metallic inner parts of the boiler. Regular removal of such Residues are therefore essential.

/ 2

909834/1222

So far, such deposits have usually been removed mechanically, i.e. by knocking or scrubbing and scraping, whereby the cleaning and rinsing effect of aqueous alkaline solutions was also used. It is already known to spray such aqueous-alkaline solutions inside the boiler by means of a special device under pressure, in order to make purely mechanical cleaning easier or superfluous (see Swiss patent specification no. 360.072).

^ As usable in the latter method, alkaline

reacting substances become alkali or alkaline earth salts with Anions of weak acids (e.g. soda, sodium bicarbonate, trisodium phosphate etc.) or alkali hydroxides are recommended. It works with fairly high salt concentrations. This results in the risk of more severe deposits of medium residues that have corrosive properties through subsequent reaction with acidic combustion products accept and possibly also store excess acid components.

As the. Practical experience has shown that the known processes also require a relatively large amount of water, since the alkaline liquid and the residues are to be largely removed from the boiler.

/ 3

909834/1222

t- / ^ ■ '' ■ ' ^: ■ ■ ■ ■; ■ ■■■■■ '■ ^":; .. ■ .-; *

■■■■■ - 3 -

It has now been found that a considerably more effective and economical boiler cleaning by using a Cleaning agent that meets the following requirements:

1. High network and penetration effect

2. Good neutralizing effect

3. Strong gas development at elevated temperature

4. Low residue build-up

An agent according to the invention which contains in aqueous solution fulfills these requirements

a) Customary anionic, amphoteric or nonionic surfactants such as alkylnaphthalene sulfonates, alkylbenzenesulfonates, alkylphenol oxyethylates and

b) thermal largely (practically completely) with evolution of gas disintegrating substances.

The substances classified under b) are preferably about substances that decompose with the development of ammonia, as this is the easiest way to achieve the desired neutralization effect. Particularly preferred (because the most economical) are compounds that break down thermally into ammonia and carbon dioxide, such as Ammonium carbonate, ammonium bicarbonate, ammonium carbamate or urea. However, connections can also be used

909834/1222 / 4

that develop other gases in addition to or instead of the gases mentioned, such as ammonium oxalate, aramonium formate or ammonium nitrite.

In principle, gas-evolving substances that do not evolve ammonia can also be used, if desired, such as compounds that serve as blowing agents for the production of plastic foams. These are substances which split off nitrogen at elevated temperatures, such as azodiearbonamide, azobutyronitrile or substituted thiotriazoles. Oxygen-evolving substances such as urea peroxide adduct can also be used, provided that they can be stored alongside the other components of the cleaning agent. If these substances are poorly or not at all soluble in water, they can also be contained in the cleaning agent in finely dispersed form. Such substances are, however, for cost reasons alone hardly used as gaeentwickelnde component, but most added to enhance the development of gas together with the above-identified, billi- cook ammonium salts.

If a substance which does not develop ammonia is used alone as component b) of the cleaning agent, an addition of ammonia can be useful in order, if necessary, to obtain a

909834/1222

_ 5 -

To achieve neutralization effect. In addition, ammonia can be added also take place when using an ammonia-releasing substance, if a stronger alkalization is desired.

It is entirely possible and can be expedient to combine several substances which decompose thermally with evolution of gas to be used with one another, just as different surfactants can be used side by side.

The effectiveness of the agents according to the invention can also can also be increased by additives that bring about a certain protection against corrosion of the treated metal surfaces are suitable, such as ammonium phosphate or zinc phosphate. Also additives as a result of their oxidizing effect or catalytically support the removal of the soot and tar fractions that form deposits, promote the effectiveness of the new remedy. Such additives are ammonium nitrate or ammonium chromate or copper or zinc salts (preferably in the form of their ammoniacates). Of course- ™ These additives can be borrowed insofar as they are compatible with one another and with the two obligatory components of the agent according to the invention are also present next to each other.

909834/1222

- ο -

When the agent according to the invention is used, a surfactant content of 0.1-4 $, preferably about 0.3-0.7%, is generally sufficient . The content of thermally easily decomposable substances can be of the same order of magnitude is thus significantly lower than the content of alkaline substances in the boiler cleaning agents according to the prior art. The content of non-mandatory but beneficial additives can be less than $ 1 each.

The agent according to the invention is sold because of the. associated tree savings, however, expediently in higher concentrated solution, which the user then adjusts himself to the prescribed application concentration with water is to be diluted.

The agent according to the invention can be used in boiler cleaning as follows;

The aqueous solution of the above components is after Dilution to the prescribed application concentration is sprayed into the boiler, for which a commercially available spray. . device of sufficient power (such as is offered for the purpose of pest control in the garden) fully ge ^ - is enough. The amount to be introduced depends on, -the · .. Thickness of the deposits that should be soaked abundantly and evenly. Then the heating is back in

. / 7 909834/1222

Put into operation, with the (mechanically effective) gas development of the thermally decomposing substances coming into operation as the temperature rises and causing the plaque to flake off and flake off in the shape of a plate or shell. At the same time, the acidic deposit components are neutralized and converted into compounds that are largely volatile at higher temperatures - whether decomposed or undecomposed. The then spray with water may therefore kept to a minimum or even completely refrain from advertising 'in the, without any adverse effects show ·

The following examples illustrate the invention without it to restrict:

example 1

Alkyl benzene sulfonate 12.0 parts

commercial ammonium bicarbonate /

carbonate mixture 15 »O parts

Ammonium phosphate 2.0 parts φ

Ammonium nitrate 6.0 parts

Water ad 100.0 parts

When using the above-described concentrate is diluted in a ratio of 1:25.

/8th

909834 /

* s> Ci ο »

illkylphenolpolygykolathsr '--- "-" - 8 _s 0

CAlky! Group ζ.Β »with 8 - Ίβ carbon atoms,

8-14 moles of ethylene oxide) 8.0 parts

organ. Nitrogen compound, & .B. ■

Pfß} 6 ₉ O parts

Combustion catalyst 6.0 parts

Water ad 100.0 parts

When using the concentrate described above is diluted in a ratio of 1 s 20.

/ 9

909834/1222

Claims (3)

Claims Means for cleaning boilers on the combustion side, characterized in that it is in aqueous solution a) common ariionic, amphoteric or nonionic Surfactants and ^ j b) Substances which largely decompose thermally with strong evolution of gas, preferably ammonia and carbon dioxide evolving compounds. 2. Means according to claim 1, characterized in that the concentration of the usual surfactants as well as that of the Thermally decomposable substances with evolution of gas, 0.1-4 percent by weight, preferably 0.3-0.7 percent by weight. ^ j 3. Means according to claim 1, characterized in that In addition to the components mentioned in claim 1, there are also corrosion inhibitors and / or soot or tar combustion ' Contains promotional agents. 909834/1222