DE2027971A1 - Water in oil emulsion as fuel for lime prodn - by burning lime-stone - dolomite etc - Google Patents

Abstract

Water-in-oil emulsion is used as fuel for burning limestone in a shaft kiln pref. with impulse burner to give increased output and lime of improved quality. The emulsion consists of 70-97% residue oil, fuel oil or combustion oil esp. heavy oil, 30-3% H2O as reducing agent and pref. a carboxylic acid with 10-24C atoms or its alkali or alkaline earth metal salt as emulsifying agent.

Description

Burning limestone in lime shaft kilns When burning limestone (CaCO3), dolomite stone (CaCO3.MgCO3) and limestone-clay stones or marl in lime shaft kilns there has been a changeover to heating oil with suitable fuel oil instead of pure coke-firing Use burner systems to increase the economic efficiency compared to coke and improve the quality of the lime.

On the one hand, when using heating oil, however, temperatures are too high occur and on the other hand the combustion temperatures in the limestone range A temperature of 1300 ° C should not be exceeded, it has been suggested that To cool down oil gas by water injection. Apart from the fact that in this procedure However, the generator is discontinued at least once a day to remove residual coke must be, the addition of water is uneconomical and requires more complicated Plants and ovens.

Another suggestion is to limit the temperature with Gasification burners carried out a partial combustion and thereby the temperature the products of combustion kept low upon entry into the fire zone; such However, methods can only be used with furnaces with an inner diameter of up to 2 1/2 m will.

About the disadvantageous and uneconomical influence of the addition of water to fix and still allow a limited temperature on the limestone msn oil burners installed under fire bridges. Here. Difficulties arose in terms of the service life of the most flammable material and the operating costs.

The perform procedures for lime burning with oil firing without additional Internals are also due to the low penetration depth of the fuel jet on furnaces with lower outputs of up to about 100 tons / day and correspondingly smaller Inner diameter limited.

Because of the desired larger penetration animal of the Fouerzone or des The flame area is also used to prevent premature spraying of the oil In the case of stoves with pulse burners, the heating oil is fed into the non-atomized as a closed jet rotgitihende heap of the fire zone shot.

In principle, the shaft furnace is used as an oil gas generator, because the heating oil gasifies and cokes like a blow when it hits the stone. That Oil gas penetrates to the furnace axis due to the development of pressure and in search of oxygen deeper into the middle of the shaft; the coke formed burns on the stone surface slowly from.

At the burner only purge air is added to prevent that gases enter the burner tube closed at the rear. In this procedure: one usually uses heavy fuel oil, since a lighter fuel oil is too close to it ignite the furnace wall and cause overheating in the burner tube and on the furnace wall would lead. With such pulse burners 4 to 12 burners are in two to four levels are provided, the burners in each level by a heated ring main connected, and the hosing down of the burner electronically goateuert to a. given program takes place.

In this per se preferred method, however, the oil gas does not penetrate more than a maximum of 1.2 m into the pile, so that in shaft furnaces with larger Diameter than 2.5 m in the remaining central cross-section of coke from above or Gas must be added from below. There is another disadvantage with these C) ths in the fact that often at more than 80% of the nominal power an impermissible soot emission occurs, so that either significant air pollution occurs and the exhaust gases are no longer usable or that the ovens are below the rated output must be operated.

An addition of air to the pulse burners to improve the soot burn-off but again easily leads to local overheating, which can damage the Furnace wall and melting or sintering of the goods, especially when loading with lime of different quality can result.

The present invention has now faced the issue, lime burning can be carried out more economically in shaft furnaces using oil firing, However, without these furnaces because of the formation of soot with a lower rating than to operate when using coke.

The use of a water in emulsion is used to solve this problem with a content of 70 to 97 X oil, in particular heavy oil, residual oil, heating oil or Brenndl, and 30 to 3 seconds of water as a reducing and heating agent for oil-fired ones and, if necessary, lime shaft furnaces with coke, in particular for shaft furnaces proposed with pulse burners. A water-in-oil emulsion is preferably used, in which a fatty acid is used as an emulsifier with 10 to 24 carbon atoms or their alkaline earth salts are used.

Surprisingly, when such a water-in-oil emulsion is used, one obtains excellent performance and effect without the feared inefficiency occurs due to the addition of water. This effect is all the more surprising since one has so far believed that when burning water-in-oil emulsions, for example as with heating systems or internal combustion engines, due to which the evaporation is smaller Numerous micro-explosions resulting from water droplets in the closed oil phase a premature and particularly intensive atomization of the oil would have to take place but because of the premature burning in the vicinity of the wall area and because of the too always had to be switched off at high temperatures.

In addition, it was to be assumed that when water is added via a water-in-oil emulsion at temperatures above 830 ° C, more carbon monoxide and less carbon dioxide is produced, since according to the equation of the water gas equilibrium CO + H2O # CO2 + H2 the reaction continues the left side is moved; in this case the excess carbon monoxide in a mixture of water vapor and the heated calcium oxide that has already formed would again form calcium carbonate with evolution of hydrogen according to the equation CO + CaO + H20 CaCO3 + H2 regress, especially since the equilibrium of carbon monoxide and oxygen 2C0 + 2CO2 is strongly shifted to the left at high temperatures.

Surprisingly, however, it has been found that some are still unexplained Reasons for these adverse reactions do not occur and the shaft furnaces also with larger: n diameters can be driven with a nominal power that of a power of coke-fired ovens.

In addition, there are no impermissible or excessive soot emissions on and the flames are within the desired temperature range between 900 ° and 1100 ° C, with no caking or sintering of the pile and none Damage to the furnace wall occurs. In particular, are heated with pulse burners Ovens the kidney-shaped combustion zones in the area of the pulse burner very much shifted more than before into the middle of the shaft furnace. This probably is due to the fact that when the water-in-oil emulsion was injected before the impact Surprisingly, no evaporation or spraying or spraying on the glowing stone. The highly volatile oil components are atomized because of the water present, But this then in the flame area much more strongly with a considerable increase in volume occurs and creates a flame area that extends deeper into the furnace. Through this is it is possible for shaft furnaces with a larger diameter than before, both To achieve full nominal output without soot formation in suction furnaces as well as pressure furnaces or even exceed it.

Cationic, anionic and nonionic emulsifiers can be used as emulsifiers as well as mixtures thereof can be used. Suitable emulsifying agents are Salts of long chain aliphatic carboxylic acids, especially the alkali salts of Fatty acids have 12 to 24, preferably 15 to 20 carbon atoms in the molecule, e.g. Sodium oleate, sodium stearate or xethylene oxide and propylene oxide condensation products, e.g. polyoxyethylene sorbitan trioleate, sodium aryl sulfonate, the sodium salt of sulfonated castor oil. Preferred emulsifiers, however, are fatty acids with 10 bia 24 carbon atoms or their alkali or

Alkaline earth salts.

Example A furnace with a nominal output of 150 t / day and with an inner diameter of 3.8 m filled with limestone in 80/140 mm increments. The firing was done 70% with heavy fuel oil and 30% with the core of the Coke present in the furnace. Because of the excessively high soot emissions, the output had to be 132 t / day.

Using the method according to the invention, the same furnace was used with the same feed but with a water-in-oil emulsion of the following Composition operated: 88.7% by weight heavy fuel oil D45 0.942, viscosity 2.8 E0 at 1000C calorific value 1 9780 kcal./kg 11 wt.% water 0.3 wt.% emulsifier (fish fatty acid) When the furnace was operated according to the method according to the invention, an output of 151 t / day achieved without significant soot emissions, whereby a reactive, soft, quick lime of excellent quality was obtained.

Claims (2)

P a t e n t a n s p r ü c h e 1. Use of a water-in-oil emulsion with a content of 70 up to 97% oil, in particular heavy oil, residual oil, heating oil or fuel oil, and 30 to 3% water as a reducing and heating agent for oil-fired and possibly with Lime shaft ovens charged with coke, especially for lime shaft ovens with pulse burners. 2. Use of a water-in-oil emulsion according to claim 1, characterized known that the emulsion is a fatty acid with 10 to 24 carbon atoms, or their alkali or. Contains alkaline earth salts as an emulsifier.