WO1988009368A1

WO1988009368A1 - Composition and process for cleaning of fire-side parts of firing devices

Info

Publication number: WO1988009368A1
Application number: PCT/HU1988/000035
Authority: WO
Inventors: György SCHAMSCHULA; Miklós BRÓDY; Csaba BÁNYAI; Attila Kocsis; József Kovács; Miklósné BRÓDY
Original assignee: Schamschula Gyoergy; Brody Miklos; Banyai Csaba; Attila Kocsis; Kovacs Jozsef; Brody Miklosne
Priority date: 1987-05-19
Filing date: 1988-05-18
Publication date: 1988-12-01
Also published as: EP0314750A1; HU198096B; HUT46733A; PL272544A1

Abstract

A composition for cleaning of fire-side parts of firing devices, containing an oxidating agent, a tenside and a compound assuring a basic milieu. Application of such a composition makes possible to remove any combustion deposits from boilers without any corrosion effect and the surface will be clean to metal after a simple rinse with water.

Description

Composition and process for cleaning of fire-side parts of firing devices

Field of the invention

The present invention relates to a composition for cleaning of fire-side parts of firing devices and a cleaning process applying this composition. Fire-side parts of boilers stoked with solid fuel, gas or oil need a permanent cleaning to remove combustion deposits from the boiler bottom, flue system and fire-tubes, because in consequence of these deposits the heat transfer coefficient is getting worse, fire-tubes and flue-system become chocked because of sooting as a consequence of the disadvantageous changing of the flue gas composition, etc.

Prior art

Both physical and chemical methods are known in the art for cleaning of fire-side parts of firing devices. Physical methods are slow, with poor efficiency, complicated and noxious to health.

There are many ideas for the chemical cleaning. Greater part of the wide-spread chemical cleaning compositions are alkaline. Although acidic cleaning compositions also may be used, because these ones dissolve well the deposits on the fire side-parts and structural parts of the boiler removing them therefrom, but they are very corrosive, which is inadmissible in respect for the safe operation of the firing device.

Applicability of a part of these compositions is based on their alkalinity only; they themselves are unsuitable to produce a surface clean to metal which is necessary for the testing of the boiler. One of the known solutions is published in the Hungarian Patent No. 171 436; the composition described in it contains sodium hydrogen carbonate or sodium carbonate and a water soluble amine, such as triethanolamine, diethanolamine and/or triethanolamine phosphate in an aqueous solution. According to the description the composition may be sprayed with a pressure of 3-6 atmospheres (about 44-88 psi) into the boiler at a temeprature of 60-70ºC in carbon dioxide stream onto the surface to be cleaned. Carbon dioxide is necessary, because the formed triethanolammonium carbonate would decompose in air and could not display its cleaning effect.

The process is relatively complicated and expensive. Object of the present invention is to obtain a composition for cleaning of fire-side parts of firing devices, which composition can be uged at elevated temperatures without a protecting atmosphere, furthermore results in a better efficiency of cleaning, and removes above all the sulfur compounds and persistent tarry sootings more effectively.

Disclosure of the invention

It has been found, that a composition containing an oxidating agent, a tenside and a compound suitable to maintain a basic milieu suites the aforementioned requirements and may be applicable for the effectual removal of inorganic and organic combustion deposits from fire-side parts of boilers stoked with any fuel.

One of the ingredients of the composition according to the present invention is an oxidating agent, which is suitable for the rapid oxidation of organic filth and incrustant substances, making them soluble in water and oxidizing the sulfur compounds to sulfuric acid freely soluble in water. The resulting sulfuric acid, however, in consequence of the basic milieu maintained by the composition forms immediately a neutral sulfate salt, which is not corrosive under the given conditions, so no corrosion effect occurs.

The oxidizing agent in the composition may be hydrogen peroxide or any other water soluble peroxide compound with an oxidating feature, such as urea hydrogen peroxide addition compound. The proportion of the oxidating agent in the composition may be generally about 1 to 15%, preferably 2 to 10% on the basis of the total mass.

The removal of the incrustant substances made water soluble by the action of the oxidizing agent from the metallic surface of the boiler may be significantly improved by the tenside component of the composition, which promotes both the stabilization of foam formation in the basic milieu and is suited for the removal of the greasy constituents of the sooting. The tenside may be ionic or non-ionic, e.g. an alkylsulfate, alkylsulfonate or alkylarylsulfonate. The proportion of the tenside in the composition may be generally about 5 to 25%, preferably about 10 to 20% on the basis of the total mass. The alkalinity of the composition may be assured practically by an alkali metal hydroxide, carbonate or hydrogen carbonate. Proportion of it may be generally about 65 to 94%, preferably about 70 to 88% on the basis of the total mass of the composition. The amount of the compound maintaining the basic milieu has to be enough to change the sulfuric acid forming on the action of the oxidizing agent into the appropriate sulfate salt immediately and to maintain the basic milieu.

A composition of this invention may include the oxidating agent, the tenside and the compound maintaining the basic milieu together in a single admixture in solid foriu, however, it may include only the tenside and the oxidizing agent in an admixture, to which the oxidizing agent may be given in form of an aqueous solution immmediately before using .

Using a composition according the present invention the effect of the oxidating agent is irreversible, because in the basic milieu the oxidized incrustant substances are transferred into the foam by the frothing agents, therefore they can not deposit again on the surface of the boiler and the foam containing the dirt can be completely removed by washing with water and the surface will be clean to metal.

The composition according to the present invention is also suitable for cleaning firing devices cooled only to a temperature of about 80-90ºC, because it does not decompose even at this temperature, it is not necessary to use an inert carrier gas, it is also effective in presence of air and it is suitable for the removal of any combustion deposit from boilers. The following examples are intended to illustrate some characteristic compositions of the present invention and are in no way intended to limit the invention except as limited in the appended claims.

Example 1

A composition in form of powder contains the following ingredients:

Sodium hydrogen carbonate 70 grams,

Sodium dodecylbenzenesulfonate (Ultra^®) 20 grams, Urea hydrogen peroxide addition compound 10 grams.

5 grams of the obtained 100 grams of powder are dissolved in 1 litre of water at room temperature. Example 2

30 grams of sodium hydrogen carbonate, 50 grams of anhydrous sodium carbonate and 20 grams of sodium dodecyl- benzenesulfonate (Ultra^®) are admixed, thereafter 4 grams of the thus obtained 100 grams of powder are dissolved in 1 litre of water. To the resulted solution 11 grams of 30% aqueous hydrogen peroxide solution are added.

Claims

Claim s

1. A composition for cleaning of fire-side parts of firing devices in form of a powder or an aqueous solution comprising an oxidating agent, a tenside and a compound assuring a basic milieu.

2. A composition according to claim 1 in which the amount of said oxidating agent is ranging from about 1 to about 15 percent, that of the tenside is ranging from about 5 to 25 percent and the amount of the compound assuring a basic milieu is ranging from about 65 to about 94 percent on the basis of the total mass.

3. A compound accordinq to claims 1 or 2 in which said oxidating agent is hydrogen peroxide or urea hydrogen peroxide addition compound.

4. A composition according to any of the claims 1 to 3 in which said tenside is an alkylsulfonate, alkylarylsulfonate or alkylsulfate.

5. A composition according to any of the claims 1 to 4 in which the compound assuring a basic milieu is an alkali metal hydroxide, carbonate and/or hydrogen carbonate.

6. A composition according to any of the claims 1 to 5 characterized in that it contains a tenside and a compound assuring a basic milieu in an admixture to which the oxidating agent will be given later.

7 . A composition according to any of the claims 1 to 6 characterized in that it is in form of an aqueous solution 8. Process for cleaning of fire-side parts of faring devices characterized in that a composition any of the claims 1-7 will be applied in form of an aqueous solution of about 0.5 to 10% on basis of the total mass onto the stroutural parts of the firing device at a temperature not more than 90ºC, and thereafter the cleaned surface will be rinsed with water.