KR20010105294A - Fuel additive for bituminous heavy oil/water emulsion fuel and method of combustion - Google Patents

Abstract

Fuel additives for addition to the bituminous heavy oil / water emulsion fuels of the present invention are dispersed peptizers which are particles of magnesium hydroxide, polycarboxylic acids and / or salts thereof, salts of phosphoric acid, polyphosphoric acid, silicic acid, carbonic acid, sulfuric acid, boric acid or hydrochloric acid. (deflocculant), and saturated or unsaturated fatty acids and the rest water.

Description

Fuel Additives and Combustion Methods for Bituminous Heavy Oil / Water Emulsion Fuels {FUEL ADDITIVE FOR BITUMINOUS HEAVY OIL / WATER EMULSION FUEL AND METHOD OF COMBUSTION}

The present invention relates to fuel additives and combustion methods for bituminous heavy oil / water (hereinafter referred to as "O / W") type emulsion fuels. More specifically, the present invention does not adversely affect the dispersion stability of fuel emulsions even when added in large quantities, but rather helps to improve the stability, prevents high and low temperature corrosion of the boiler during fuel combustion, and prevents unburned carbon Orinoco tar with high content of vanadium, sulfur and nitrogen, which prevents damage from SO ₃ and NO _x and improves the heat absorption of the heating side, allowing the boilers to operate stably for a long time It relates to fuel additives for emulsion fuels of bituminous heavy oil and water, such as (Orinoco tar). The invention also relates to a method of burning such a fuel.

Bituminous heavy oils, such as orinoco tar and Athabasca bitumen, are syrups or semi-solid superheavy oils at 400 ° C. or higher, containing 60-70% or more heavy fractions in their non-flowing state. (superheavy oil).

These oils are so rich that they cannot be used as easily as petroleum. In addition, since these oils contain high levels of heavy metal vanadium as well as sulfur and nitrogen, the boilers in which they are used when used as fuel must be well maintained to prevent corrosion and slagging. In addition, the exhaust gases generated during the combustion process have to be treated by environmental measures that are much more stringent than before. Due to these problems and drawbacks, the commercial use of such heavy oils has been delayed.

Recently, however, techniques for forming O / W emulsion fuels have been developed by adding water and surface active agents to orinoco tar. This allows the heavy oil to be readily used and transported. The recoverable reserves of these oils are vast, equivalent to the reserves of oil throughout the Middle East. Thus, such oils are rapidly becoming available for reasons including the fact that they must be able to obtain a stable supply without interference from the Petroleum Exporting Countries (OPEC), and that the oil is cheap and the thermal power plant can be converted to use oil. It was used as a new fuel in Japan, Canada, the United Kingdom, and China.

Problems associated with the use of bituminous emulsion fuels include rapid corrosion of hot pipe parts such as superheaters and reheaters due to ash from combustion collected inside the boiler and high temperature corrosion by vanadium contained in such a large amount in oil content. It is. These fuels also contain high levels of sulfur and nitrogen and therefore require increased environmental measures. Another problem is related to the high content of ash included. Specifically, a large amount of adhered ash will reduce the heat absorption in the furnace, which increases the temperature inside the furnace and the temperature of the exhaust gases, There is a risk of reducing the length of time that can be operated continuously.

There is a method for preventing high temperature corrosion and sulphide corrosion, increasing combustion efficiency, and suppressing the generation of harmful substances by combustion. This method involves the use of magnesium hydroxide, magnesium acetate, magnesium nitrate, calcium hydroxide, calcium carbonate, dolomite or other alkaline earth metal compounds or iron sulfate and mFeO in oil / water or water / oil (hereinafter referred to as "W / O") emulsions The fine particles of the iron compound represented by nFe ₂ O ₃ (where m and n are zero or more numerical values) are dispersed to form a fuel additive, which is then added individually or as a mixture to the fuel or charged to the combustion furnace. do.

However, the above-described prior art fuel additives differ from A, B and C heavy oil, coke oil, asphalt, diesel, secondary oil and other such oils, which are essentially different from the bituminous heavy oil / water emulsion fuel of the present invention. Same for oil type fuel. As described below, it was not possible to use such prior art fuel additives for O / W emulsion fuels because of the strong side effects on emulsion fuels without modification.

Unlike oil type fuels, bituminous heavy oil / water emulsion type fuels contain small amounts of water present in the continuous phase. For example, in the case of Orinoco tar O / W emulsions (called orimulsion), the amount of water in the continuous phase amounts to about 30% by weight or less. Since more than about twice that amount of bituminous heavy oil fine particles are dispersed in this small amount of water, the particles collide and coalesce to destabilize the dispersion. This is why with regard to fuel additives for bituminous heavy oil / water emulsion fuels, it is considered very important that the additives do not adversely affect the stability of the emulsion.

However, surface active agents used in prior art fuel additives of this type destabilize the active materials of O / W emulsion fuels. Even the addition of magnesium hydroxide diluted in water even affects the dispersion stability of the O / W emulsion fuel, causing coagulation of heavy oil particles, resulting in the separation of semi-solid heavy oil and water.

It is an object of the present invention to provide a fuel additive that allows magnesium hydroxide to be added uniformly to bituminous heavy oil / water emulsion fuels, even when added in large quantities, which helps to substantially improve the stability without adversely affecting the dispersion stability of the emulsion. It is.

Both JP-A HEI 10-53778 and PCT-JP-A HEI 10-508898 disclose methods for adding magnesium, iron acetate, sulfuric acid, nitrates or hydroxides directly during the preparation of O / W emulsion fuels. In the case of orinoco tar, the oil may already contain magnesium nitrate. However, due to country-considered circumstances and demands, these oils have recently been formulated to contain no magnesium compounds; Oil imported into Japan contains no magnesium at all.

Previously, the maximum concentration of magnesium hydroxide in the magnesium hydroxide slurry fuel additive was about 35% by weight. In order to further increase this concentration, it is necessary to increase the size of the particles.

It is a further object of the present invention to provide an inexpensive fuel additive with 60% by weight of magnesium hydroxide particles having a maximum concentration of 0.1 to 10 μm in diameter, more preferably 0.5 to 5 μm.

In order to achieve the above object, the present invention

(1) magnesium hydroxide having a particle size of 30 to 60% by weight of 0.1 to 10 µm;

(2) 0.1 to 1 weight percent polycarboxylic acid and / or salt thereof;

(3) 0 to 1% by weight of a dispersion peptizing agent comprising at least one of Li, Na, K, and NH ₄ salts of phosphoric acid, polyphosphoric acid, silicic acid, carbonic acid, sulfuric acid, boric acid and hydrochloric acid;

(4) 0 to 0.5% by weight of saturated or unsaturated fatty acids having 8 to 22 carbon atoms and

(5) Provide a fuel additive for a bituminous heavy oil / water emulsion fuel comprising the remaining weight percent water.

In addition to the above components, the fuel additive of the present invention

(6) an iron compound having a particle size of 1 to 10% by weight of 0.1 to 10 µm;

(7) 0.01 to 1% thickener and

(8) further comprises 0.1 to 10% by weight of hydrocarbon oil.

The object is also achieved by a method of combusting a bituminous heavy oil / water emulsion fuel, comprising adding fuel additive to the fuel and burning the fuel additive or directly to the combustion atmosphere.

By combining components from those specified above to form a fuel additive, it is possible to obtain magnesium hydroxide particles of the highest concentration having a particle size of 0.1 to 10 μm. In addition, it can be easily mixed with bituminous heavy oil / water emulsion fuel, which helps to easily disperse the emulsion and even stabilize the emulsion. Therefore, it is possible to prevent high temperature corrosion of the boiler or the like, to prevent problems caused by the combustion gas, to improve the heat absorption rate of the heating surface, and to operate the boiler stably for an extended period of time.

Details of each component of the fuel additive of the present invention are described below.

The magnesium hydroxide (1) and the iron compound (6) are for protecting the boiler from various problems or to prevent such problems. The magnesium hydroxide and iron compounds used have a particle size of 0.1 to 10 mu m.

Water-soluble magnesium, such as magnesium sulfate or magnesium acetate, can be supplied to the combustion atmosphere as a homogeneous liquid component, and it is known that such combustion produces ultra-fine (10-50 mm diameter) magnesium hydroxide (MgO) particles. However, if the particles thus produced are too small, there is a drawback that the initial adhesion (yield) with V ₂ O ₅ at the pipe surface is poor. Another problem with very small particles is that the soot removal performance of the soot blowers encounters poor flowability of the uniform particles.

Even when a slurry having dispersed component particles is supplied to the combustion atmosphere, if coarse particles having a diameter of 10 µm or more are used, the specific surface area of the particles becomes too small, and in addition to reducing the stability of the slurry, the corrosion component (V ₂ O ₅ , SO ₃ ) to lower the reactivity. For this reason, it is preferable that the magnesium hydroxide (1) and the iron compound (6) used in the fuel additive of the present invention have a particle size of 0.1 to 10 mu m, more preferably 0.5 to 5 mu m.

Polycarboxylic acids and / or salts thereof (2), dispersing peptizing agents (3) and saturated or unsaturated fatty acids (4) are used to disperse magnesium hydroxide (1) and iron compounds (6), polymers, copolymers Or a copolymer with another copolymerizable monomer or salts such as (meth) acrylic acid, itaconic acid (anhydride), maleic acid (anhydride) and the like. Sodium, potassium, lithium and NH ₄ are suitable salts. These molecular weights are excellent in 3000-50000. Examples of those that may be used include (a) acrylic acid polymers, (b) methacrylic acid polymers, (c) maleic anhydride, itaconic anhydride, maleic acid and itaconic acid, and acrylic acid, methacrylic acid, methylvinyl ether and Copolymers with at least one of the other copolymerizable monomers (vinyl compounds), (d) copolymers of acrylic acid with alkyl methacrylates, (e) maleic acid polymers of methacrylic acid and polybutadiene, and (f) meta Acids and salts of maleic acid compound polymers of acrylic acid and styrene / butadiene copolymers.

Dispersion agglomeration dispersant (3) comprises at least one of Li, Na, K or NH ₄ salts of phosphoric acid, polyphosphoric acid, silicic acid, carbonic acid, sulfuric acid, boric acid, hydrochloric acid. Examples of which may be used include tertiary phosphates such as Na ₃ PO ₄ , metaphosphates such as (KPO ₃ ) _n , pyrophosphates (diphosphates) such as Na ₄ P ₂ O ₇ , polys such as Na ₅ P ₃ O ₁₀ Phosphate (triphosphate), hexametaphosphate such as (NaPO ₃ ) ₆ , lithium silicate, sodium silicate (water glass numbers 1, 2, 3), carbonate, sulfate, metaborate such as NaBO ₂ , Na ₂ B ₄ O Tetraborate such as ₇ , sodium chloride, ammonium chloride and hydrates thereof.

Component 4 of the fuel additive is a saturated or unsaturated fatty acid having 8 to 22 carbon atoms. Examples of what can be used include branched fatty acids such as 2-ethyl hexanoic acid (eight carbon atoms) and isostearic acid (18 carbon atoms); Saturated fatty acids such as lauric acid (12 carbon atoms), stearic acid (18 carbon atoms) and behenic acid (22 carbon atoms); Unsaturated fatty acids such as oleic acid (18 carbon atoms), linoleic acid (18 carbon atoms), and erucic acid (22 carbon atoms); And mixtures thereof.

The iron compound (6), a component of the first group which is added as needed, as in the case of the magnesium hydroxide component (1), helps to protect the boiler from various types of harmful effects and prevents this problem. Iron compounds are used in particulate form and the diameter of the particles is 0.1 to 10 μm. Examples of those that can be used include Fe ₂ O ₃ (red iron oxide), Fe ₂ O ₃ · H ₂ O (FeOOH, goethite, yellow iron oxide) and Fe ₃ O ₄ (triiron tetraoxide, magnetite).

Thickening agent 7, a component of the second group which is added as necessary, is used to improve the dispersion stability of the fuel additive. Specifically, it is used to maintain the viscosity (at 20 ° C.) between 500 and 1500 (mPa · s). Examples of what may be used include inorganic thickeners such as sepiolite and bentonite, and organic thickeners such as carboxymethyl cellulose (CMC) and methyl cellulose (MC). Mesophilic stone is a functional magnesium silicate having the chemical formula Si ₁₂ Mg ₈ O ₃₀ (OH) ₄ (OH ₂ ) ₄ .8H ₂ O. Its thixotropic property has long been used to increase viscosity and prevent precipitation and dripping. Bentonite is different in composition from crypts but has similar properties. Bentonite is used to thicken paints, inks and other liquid compositions. Methyl cellulose is obtained by methylating cellulose esters. Carboxymethyl cellulose may be called a derivative of methyl cellulose. They are widely used mainly as glues.

Hydrocarbon oil 8, a third group of components added as needed, is used to reduce the viscosity of the fuel additives by itself and to promote flow characteristics and contact between magnesium hydroxide and other components and bitumen particles. Examples include kerosene, diesel, A, B and C heavy oil and other mineral oils.

In the fuel additive consisting of the above components, the particulate components used to prevent or prevent the harmful effects on the boiler are (2) magnesium hydroxide, (3) dispersion peptizers dispersed by polycarboxylic acid and / or salts thereof. And (4) saturated or unsaturated fatty acids and, if necessary, (6) iron compounds (powder components), (7) thickeners, and (8) hydrocarbon oils.

The ratios and amounts of magnesium hydroxide (1) and iron compound (2) to be added vary depending on the operating conditions, the type of boiler and other factors, and should be determined according to the purpose considered. Suitable component ratios of the dispersants (2), (3) and (4) depend on the concentration of the particulate components (1) and (6). In general, high concentrations of particulate components require higher amounts of dispersant (2), (3) and (4), and in particular require an increase in the amount of (2) or (3), or both. .

Similarly, the suitable ratio to the thickener 7 depends on the concentration and distribution of the components (1) and (6). In general, the lower the concentration of these particles, the greater the amount of thickener 7 needed. However, it also depends on the amounts of components (2) and (3). The lower the viscosity, the higher the thickening agent 7 needed.

The range of the above-described ratios of the particulate components (1) and (6) is a range suitable for solving the problems associated with combustion. These ranges should be adapted to factors such as working conditions and boiler type. This avoids the problems caused by unburned carbon, SO ₃ and NO _x , and also improves heat absorption by the heating surface. As a result, the boiler or the like can be operated stably for an extended period of time. Problems related to combustion are not solved if the ratio is outside the stated range.

With regard to the dispersants (2), (3) and (4), a range that ensures good dispersion of the fine components (1) and (6) in water (5) is specified. This range also ensures stability when fuel additives are added to the bituminous heavy oil / water emulsion fuel. Within this range, the stability of the fuel additive slurry is maintained and the addition of additives does not adversely affect the dispersion stability of the bituminous heavy oil / water emulsion fuel, even when added in large quantities. In practice, this stability can be improved by the addition of additives to produce a homogeneous mixture without separating particulate components and to maximize the effect of the components. Outside of the specified ranges, the stability of the fuel additives may be degraded and addition to the bituminous heavy oil / water emulsion fuel may adversely affect emulsion stability. Particularly when a large amount is added, agglomeration of the heavy oil particles may be caused to separate the mixture into semisolid heavy oil and water.

Examples of the present invention will be described below. However, it should be understood that the present invention is not limited to the following examples.

Example 1

Regarding the composition ratios shown in the attached Table 1, specific amounts of (1) magnesium hydroxide, (6) iron compounds, (2) polycarboxylic acids and / or salts thereof, (3) dispersion peptizers, (4) saturation Or totally unsaturated fatty acids, (7) thickeners, (8) hydrocarbon oils, and (5) water in total to 300 g. The mixture was stirred at 3000 rpm for 30 minutes to obtain a stable water-slurry fuel additive. In Comparative Examples 1 and 2, the composition is prepared from (2) polycarboxylic acid and / or salts thereof, (3) dispersion agglutination agent, (4) saturated or unsaturated fatty acid, (7) thickener and (8) hydrocarbon Prepared without adding oil.

Characteristics of fuel additives, stagnation stability and mixture stability:

Specific gravity and viscosity of the fuel additive mixtures 1 to 10 and Comparative Examples 1 and 2 were measured, and the stagnation stability and the mixture stability were investigated. The results are shown in Table 2 attached.

Stagnation stability; Stagnation stability of fuel additives

The results described in Table 2 are based on the following criteria.

The stability of the fuel additive was evaluated after one month of stagnation time.

(Double-circle): Excellent water-slurry stability with supernatant by several% separation.

O: supernatant by about 10% upper layer separation.

(Triangle | delta): The supernatant liquid by 20-30% upper part separation.

Ｘ: 50% or more separation, solidification of separated particles.

Mixture stability; Stability of a Mixture of Additives and Bituminous Heavy Oil / Water Emulsion Fuels

The results listed in Table 2 are based on the following criteria.

20 g of bituminous heavy oil / water emulsion fuel (having the properties listed in Table 3 attached) and 2 g of fuel additive were mixed and stirred in a Petri dish for 1 minute using a glass rod.

◎: No change in mixture.

O: Observation of a small ubiquitous small heavy oil aggregate.

Ｘ: complete decomposition of the emulsion; Observation of heavy heavy oil aggregates.

Example 2

Fuel additive mixtures 3, 5 and 7 were forced into the fuel line of the boiler, respectively, to mix the fuel additives with bituminous heavy oil / water emulsion fuel. The ratio of the mixture was 1 part of additive to 500 parts of fuel. The boiler was then operated while injecting a mixture of additives and fuel into the boiler, respectively. The amount of NO _x , SO ₂ and soot produced thereby was measured at the outlet of the air-heater of the boiler. SO ₃ was measured at the economizer outlet. To measure corrosion, the test pieces (JIS G3101 SS-41) were suspended in an air heater and the test pieces (JIS H3462 STBA-24) were suspended in a superheater. For comparison, a fuel containing no additives was used. The results are shown in Table 4 attached.

The present invention is not limited to the above embodiments, and such variations may be modified to the extent that they are within the defined scope of the present invention.

The fuel additives of the present invention described above can be added in large quantities to bituminous heavy oil / water emulsion fuels without adversely affecting the dispersion stability, and can improve the stability. Therefore, the use of such a bituminous heavy oil / water emulsion fuel containing the additive of the present invention prevents high and low temperature corrosion of boilers and the like, and prevents interference with combustion, so that the boilers and the like operate stably for a long time. To do it.

Claims (9)

(1) magnesium hydroxide having a particle size of 30 to 60% by weight of 0.1 to 10 µm; (2) 0.1 to 1 weight percent polycarboxylic acid and / or salt thereof; (3) 0 to 1% by weight of a dispersion peptizing agent comprising at least one of Li, Na, K, and NH ₄ salts of phosphoric acid, polyphosphoric acid, silicic acid, carbonic acid, sulfuric acid, boric acid and hydrochloric acid; (4) 0 to 0.5% by weight of saturated or unsaturated fatty acids having 8 to 22 carbon atoms and (5) Fuel additive for bituminous heavy oil / water emulsion fuel, comprising the remaining weight percent water. The fuel additive according to claim 1, further comprising (6) an iron compound having a particle size of 1 to 10% by weight of 0.1 to 10 µm. _{3. The} fuel additive of claim 2 wherein the iron compound is at least one selected from Fe ₂ O ₃ , FeOOH and Fe ₃ O ₄ . The polycarboxylic acid and / or salt thereof according to claim 1, wherein the polycarboxylic acid and / or salt thereof is a polymer of (meth) acrylic acid, itaconic acid (anhydride), maleic acid (anhydride), a copolymer and other copolymerizable monomers having a molecular weight of 3000 to 50000 At least one selected from copolymers, the salts thereof being Li, Na, K and NH ₄ . The fuel additive according to claim 1, further comprising (7) 0.01 to 1% by weight of a thickening agent. 6. The fuel additive according to claim 5, wherein the thickener is at least one selected from calculus, bentonite, carboxymethyl cellulose and methyl cellulose. 2. The fuel additive of claim 1, further comprising 0.1 to 10% by weight of hydrocarbon oil. 8. The fuel additive of claim 7, wherein the hydrocarbon oil is at least one selected from kerosene, light oil, A heavy oil and B heavy oil. Bituminous heavy oil / including the addition of the fuel additive according to any one of claims 1, 2, 5 and 7 to the fuel and the combustion or direct addition of the fuel additive to the combustion atmosphere. A method of burning water emulsion fuel.