JPS581720B2 - Fuel compositions useful in gas turbines - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to fuel compositions and methods for burning fuels, especially fossil fuels such as petroleum fuels, and combustible waste materials utilized separately or in conjunction with fossil fuels.

In particular, the present invention applies to power generation, propulsion systems, pipeline
It can be applied to fuel for operating gas turbines used for services and the like, and to the combustion of such fuel.

Magnesium-containing compounds have been used as corrosion-inhibiting additives in conjunction with the combustion of non-distillate fuels containing ash or inorganic contaminants, particularly metal contaminants, for gas turbine operation.

When such ash-containing fuels are used as fuels for gas turbines, the combustion effluent resulting from the combustion of such fuels contains about 1.0 ppm or less, preferably 0.5 ppm or less of alkali metals (sodium) by weight. It has heretofore been necessary to pre-treat these fuels to reduce their alkali content to a minimum level so as to yield alkali and/or potassium).

When operating gas turbines with this fuel, the use of magnesium as an additive to remove alkali metals from the fuel and/or to eliminate the presence of alkali metals in the combustion products is approximately It has heretofore been considered necessary to protect metal alloys used in the nozzles and blades of turbines operating at temperatures above 760°C (approximately 1400″F) from hot corrosion.

Magnesium is an effective addition to gas turbine fuels to reduce or avoid hot vanadium corrosion of gas turbine blades, which is most significant at temperatures above 760°C (1400”F). Although generally recognized and accepted as a component, the effectiveness of magnesium as an additive is compromised by the presence of even small amounts of alkali metals, such as sodium, in the fuel or combustion effluent gas.

This is because when both sodium and vanadium are present in the fuel, vanadium reacts selectively with sodium rather than with magnesium, resulting in less magnesium vanadate in the resulting ash, which is corrosive and has a low melting point. This is because the amount of sodium vanadate tends to increase.

Heretofore, it has not been possible to suppress the tendency of sodium to form undesirable corrosive compounds in the presence of vanadium.

Furthermore, and most importantly, magnesium cannot provide effective protection against sodium sulfide attack (commonly known as sulfidation) on turbine blades and nozzles.

At current and planned higher operating temperatures brought about by continuous industrial efforts to increase the output and efficiency of gas turbines, this sulfidation has become the most significant and even destructive problem. There is.

Additionally, the presence of alkali metals in the combustion products adversely affects the nature of the ash deposits on the turbine, which increases the clogging and convergence of the flow of combustion gases through the turbine, thus reducing power output. A rapid decline occurs;
This increases the need and frequency of flushing the turbine to remove such deposits in order to restore the turbine's output to its original design rated output.

Traditionally, when ash-containing fuels or alkali metal-containing fuels are combusted to generate combustion effluent gases for gas turbine operation, this fuel is pretreated, for example by water washing, to extract the alkali metals and water-soluble ash-forming properties from the fuel. Efforts have been made to remove compounds.

Equipment for washing mossai with water requires a considerable amount of space;
It therefore becomes a significant factor in the total cost of plant equipment.

For example, water washing of such fuels often produces water-in-oil emulsions that are difficult to break down.

These emulsions require the use of demulsifiers and usually additional centrifugal or electrostatic means or equipment to completely remove the aqueous phase containing water-soluble salts extracted from the oil phase.

Alkali metals such as sodium are used not only as contaminants in fuels, but also in marine equipment, especially ships,
Contaminants in the combustion air associated with the combustion of fuels in ports or at sea may also enter the combustion zone and combustion products.

Alkali metals, such as sodium, appear in the combustion products due to the inhalation of airborne salt (NaCl) particles or airborne salt-containing mists.

Conventionally, in order to avoid such alkali metal contamination, airborne contaminants had to be removed by flocculation equipment or filtration equipment.

Other potential sources of alkali metal pollution associated with gas turbine operation include the release of nitrogen oxides into the combustion effluent gases for gas turbine operation, particularly when the water used contains dissolved alkali metals therein. This occurs when water is injected into the primary combustion zone of the turbine to reduce

Special pretreatments, such as desalination or deionization, are required to remove alkali metals such as sodium and other metals to obtain substantially metal-free water or water of desired purity.

Paper & 74-GT-44 “GasTurbine Li” submitted at the Gas Turbine Conference held in Zurich, Switzerland from March 31st to April 4th, 1974
Quid Fuel Treatment andAn
E. Krul I entitled “Analysis”
A. by s. S. K.E. Publications describe fuel processing systems, including fuel cleaning factors and other factors related to fuel selection and processing for gas turbine operation.

The disclosure of this document is hereby incorporated in part 2.

As mentioned above, the problems faced in the combustion of ash-containing fuels, especially sodium-containing fuels, for gas turbine operation;
It is also well known to use magnesium as an additive component in such fuels to improve the life of gas turbine blades.

A commonly practiced method of using magnesium as an additive is to force the sodium in the fuel down to the required minimum level before heating at 760°C (1400°C) 1
This effectively protects the hot parts of the turbine, such as the nozzles and blades, which are operated at temperatures above 100% from corrosion at high temperatures.

Cleaning the fuel to remove sodium is considered essential for all fuels except distilled fuels to make them suitable for use in gas turbines, so this cleaning is low The cost is a significant impediment to the utilization of ash-containing oils and the general use of gas turbines for power generation in areas such as utilities, manufacturing, processing, etc.

Combustion cleaning equipment is expensive, significantly increases the construction cost/KW hour of heavy oil combustion turbine equipment, and reduces investment costs and space conditions (
(particularly important in maritime applications), increases operating costs, including operational complexity, and personnel and power requirements.

The simplification or elimination of such cleaning equipment clearly constitutes a major critical improvement and is competitive against diesel and steam generation systems that do not require fuels that comply with the restricted alkali metal specifications mentioned above. This constitutes a means of substantially improving gas turbines in a commercially available manner.

Improvements in the method of burning fuels containing significant amounts of alkali metals that allow for satisfactory operation with "as-received" fuels containing both vanadium and sodium present market potential for gas turbines. It will have a strong impact on power.

Additionally, the need for effective high temperature corrosion inhibitors and ash modifiers to avoid difficulties in handling alkali metal containing combustion effluent gases is becoming important.

This is particularly because substantially ash-free fuels, especially petroleum distillate fuels, are becoming scarce and/or expensive, and residual ash-containing fuels and their combinations with distillate fuels are becoming increasingly scarce and/or expensive. This is because it is easy to handle and relatively inexpensive.

Moreover, corrosion data shows that at higher gas turbine operating temperatures, e.g., 927°C (below +700°C) metal temperatures, magnesium is used in a 3:1 magnesium to vanadium weight ratio of virtually alkali-free fuel. This indicates that adequate protection cannot be obtained even with the use of

Our U.S. Pat. No. 3,817,722 describes a fossil fuel additive composition and its use, which additive composition is comprised of silicon and magnesium components and is used in the production of metal alloys in turbines exposed to combustion gases. and modification of ash formed in the combustion products resulting from the combustion of ash-containing fuels, such as fuels containing one or more of elemental vanadium, alkali metals such as sodium, and sulfur. It acts as both.

For more details, the above-mentioned US patent states, ``Silicon source and Magnesium source?'' The ratio of these is Si02:
Utilizing additive components in the operation of fossil fuel combustion equipment, such as those that provide combined equivalents of SiO and MgO in a ratio of MgO greater than 2:1, significantly reduces corrosion and ash deposition in such equipment. It is disclosed that it is suppressed.

For use in connection with fossil fuel fueling or gas turbine operation in furnaces, boilers, diesel engines, the additive component provides a combined equivalent of at least 0.50 parts by weight of SiO2 and MgO per part by weight of ash in the fuel. It is desirable that it be present in such an amount.

Further, in the combustion of ash-containing fuels used in connection with the operation of gas turbines in which vanadium and/or alkali metals are present in the combustion products, the above-mentioned U.S. patent states that the additive components are Si02:MgO in this component is present in an amount to provide at least 2 parts by weight of magnesium per part by weight of vanadium in the sting.
is disclosed to be such as to provide at least 2 parts by weight of silicon per part by weight of alkali metal in the fuel and/or in the air associated therewith in combustion.

In the US patent, it is stated that it is desirable and economical to use a SiO2:MgO ratio of 6:1 or higher for high sodium content fuels in connection with gas turbine operation.

It is therefore an object of the present invention to provide improved fuel compositions.

Another object of the invention is to provide an improved method of burning fuel.

Another object of the invention is the alkali metal content of the fuel composition;
For example, it is an object to provide an improved fuel composition having a sodium content greater than 5 ppm by weight.

Yet another object of the present invention is to provide a temperature of above about 760°C (below 1400°C), such as 927°C (17°C).
An object of the present invention is to provide an improved method for the combustion of high sodium content fuels for use in connection with the operation of gas turbines operating at temperatures below 0.00 or higher.

Still another object of the present invention is that the fuel composition is about 50 to 1
It is an object of the present invention to provide a useful fuel composition suitable for use in connection with gas turbine operation containing 0.00 ppm by weight of alkali metals, such as sodium and/or potassium.

Yet another object of the present invention is to provide a method for operating a gas turbine in which the hot combustion effluent gas used to operate the gas turbine contains a high alkali content, such as greater than about 5 ppm by weight.

These and other objects of the invention will become apparent from the detailed description of the invention.

By practicing at least one aspect of the invention,
At least one of the aforementioned objectives is achieved.

According to the present invention, SiO2 and Mg
Consists essentially of a silicon compound and a magnesium compound that produce O 2 and the ratio of these compounds? Si02:Mg
Combined equivalents of SiO and M where the ratio of O is greater than 2:1
Fuels with a high content of alkali metals (sodium and potassium), for example with a sodium content of 5 ppm or more by weight, or substantially free of alkali metals but in the presence of additive components such as to provide gO It has been found that distillate fuels that are combusted under conditions in which alkali metals appear in the product or effluent gas burn advantageously. A silicon to sodium weight ratio of 6:1 in the combustion products or effluent gases resulting from the combustion of the fuel.
The amount is such that it is more consistent and provides at least 2 parts by weight of magnesium for every part by weight of vanadium present in the fuel.

Additive components can be added to the fuel before combustion, introduced separately into the combustion zone in contact with the burning fuel, or added directly into the flame or initial hot combustion gases.

The present invention is generally applicable to ash-containing fuels and to the combustion of fuels under conditions where alkali metals appear in the combustion products or in the combustion effluent gases.

Fuels suitable for use in the practice of this invention include hydrocarbonaceous fossil fuels, such as petrofossil fuels, especially normally liquid petroleum fuels, distilled petroleum fuels, and residual petroleum fuels.

Distillate fuels, which are normally gaseous or liquid, tend to be substantially ash-free and are for the most part easy to handle in gas turbine operation.

However, as previously mentioned, even substantially ash-free fuels, such as distilled fuels, pose problems in gas turbine operation when:

That is, when such fuels are combusted under conditions where the combustion products contain alkali metals, for example when such fuels are exposed to salt water and the brine is not adequately removed, or when used in the combustion of fuels. Where such fuels are burned in maritime or ship installations where the air containing fine, almost microscopic salt particles or salt-containing mist, such as on board ships or in ports or similar locations, or where the flame temperature is reduced, injecting water into the combustion chamber as a means of reducing NOx emissions and the water used contains small amounts of ash-forming components or metals such as sodium;
The above problem arises.

As mentioned above, the present invention also relates to gaseous fuels useful for operating gas turbines, such as natural gas, liquefied petroleum gas (
LPG), normally gaseous and easily liquefied hydrocarbons and synthetic liquid and/or gaseous fuels;
For example, it can be applied to CO, 2, CH4, C2H6 and mixtures thereof.

The fuels are produced by liquefaction or gasification of solids, such as coal, petroleum coke, combustible wastes, petroleum residues, liquid petroleum fractions, etc.

used in the practice of the present invention [combined equivalent amount of S i 0
A wide variety of silicon and magnesium can be used as the additive components for supplying 2-MgOJ.

Compounds consisting essentially of silicon and magnesium, or mixtures thereof, have an S
Anything can be used as long as it supplies iO2 and MgO2.

The additional silicon and magnesium components can be organic compounds, inorganic compounds or mixtures thereof, and such compounds or mixtures thereof can be water-soluble, water-dispersible, oil-soluble or oil-dispersible. .

These components can be blended into the fuel separately or together before combustion, or introduced separately into the combustion zone of the fuel, or the above techniques of additive components and such that the fuel is combusted in the presence of the additive components. One or more of the methods can be employed.

As magnesium or magnesium component it is possible to use water-soluble, readily available compounds such as magnesium sulfate, eg Epnom salt, magnesium acetate and magnesium chloride.

The readily available water-insoluble magnesium compounds, such as magnesium hydroxide, magnesium oxide and magnesium carbonate, are advantageously used, preferably in dispersed or finely divided form.

Other magnesium-containing materials or compounds are useful, such as talc, magnesium clay, natural or synthetic magnesium silicates that provide both magnesium and silicon.

Organic compounds containing magnesium are also useful, including magnesium salts of organic acids such as aliphatic, naphthenic and petroleum sulfonic acids, such as magnesium petroleum sulfonate, magnesium naphthenate, and of high molecular weight carboxylic acids. Includes magnesium salts such as magnesium oleate, magnesium octoate, etc.
All of these are useful in forming the magnesium component of the special additive mixture of silicon and magnesium components according to the invention.

Finely divided silica or colloidal silica and finely divided inorganic silicates are useful as silicon sources.

Organosilicon-containing compounds are particularly useful, especially silicones, polysilicone, lower alkyl C1-C6 silicates, such as tetra-lower alkyl orthosilicate, mixed alkyl polysilicates, such as ethyl polysilicate.

These silicon-containing compounds combine SiO2 and M at combustion temperatures.
It is useful to provide a portion or all of the silicon component of an additive mixture consisting essentially of a silicon compound and a magnesium compound capable of producing gO.sub.2.

The preparation of aqueous solutions and dispersions containing the additive fractions of the invention can be carried out by any suitable and/or conventional method of preparation.

Similarly, similar operations can be used to prepare solutions or suspensions in organic solvents.

When the additive component is used in distillate or other high grade petroleum fuels, the organic solvent suspension or solution can be prepared using various light petroleum fractions, such as kerosene, mud distillate oil, and the like.

When the additive component is used with a lower grade fuel, such as a residual oil, it is preferred to use an aromatic solvent or an aromatic petroleum distillate to facilitate uniform blending or mixing with the fuel.

Suitable aromatic solvents are relatively high boiling substituted naphthalene compounds or disubstituted benzene compounds.

Typical useful commercially available compounds are (1) aromatic solvents containing methylnaphthalene fractions or naphthalene fractions from coal tar or petroleum sources, (2) alpha-methylnaphthalene and beta-methylnaphthalene fractions; (3) chlorinated solvents such as ortho-dichlorobenzene.

Other solvents are also suitable.

The benefits of implementing the invention can be achieved through many different approaches.

The first approach is to use additive components in combination or formulation with the fuel, in this case a silicon source and a magnesium source, or a fluid formulation consisting of the additive components in an aqueous or organic liquid base. A magnesium source and a silicon source uniformly dissolved and/or dispersed therein are mechanically blended with the fuel.

Such additive compositions can be readily formulated to meet the particular requirements of the fuel to be combusted and the fuel combustor.

However, as mentioned above, it should be understood that it is never necessary to add the silicon and magnesium sources at the same time.

These can be introduced separately into the fuel or into the combustion zone, so that if the fuel contains a suitable amount of either a magnesium component or a silicon component, the present invention provides two components in the combustion gas:
This can be carried out by introducing the other silicon source or magnesium source free of it in such an amount that a Si02:MgO ratio greater than 1 is provided.

It is also desirable to incorporate additive components into the fuel by means of a dispensing device if the treated fuel is required for a large-scale installation or for multiple small-scale installations.

The type of fuel combustion equipment, i.e. the turbine is operated directly with liquid or gaseous fuel, or it is operated with a pressurized boiler in which combustion takes place under pressure;
The method of utilizing the present invention will vary depending on whether auxiliary combustion is performed in front of the turbine or not, and whether the effluent combustion gas is introduced into the Wakasu turbine, or whether water is injected as described above. be able to.

In the practice of the present invention, the additive components desirably include at least 2 parts by weight each of magnesium and silicon for each part by weight of vanadium and sodium in the fuel or combustion effluent gas to the turbine.

This proportion can be increased up to 3 parts by weight, and even higher if desired, such an increase in additive components further improving ash modification and corrosion inhibition.

From a practical point of view, the upper limit for additive components is an economical one, and this decision depends on several variables, such as the cost of the additive components, as well as the cost of the fuel, the quality of the fuel, i.e. the amount and composition of the ash, and the degree of corrosion and fouling control of hot turbine components.

When the additive composition or additive is introduced into the combustion zone independently of the sting, the amount introduced generally corresponds to the amount that would be used if mixed directly with the fuel.

Gas turbine operation presents special aspects due to the substantially higher metal temperatures compared to other power generating combustion devices.

In the combustion of fuel during gas turbine operation, when vanadium and/or alkali metals are present in the combustion products, the additive component is at least 2 parts by weight, preferably for every part by weight of vanadium in the fuel or combustion effluent gas. The ratio of S t 02 :MgO of the additive component should be present in an amount providing about 3 parts by weight, with the ratio of the alkali metals introduced into the combustion zone by the fuel and the air and/or water involved in the combustion to 1 Such as providing more than 6 parts by weight silicon per part by weight.

For inland installations, alkali metals are not expected to be introduced into the combustion air.

In contrast, in gas turbines used for ship propulsion or land-based installations in close proximity to the sea, the amount of alkali metals introduced into the combustion air by salt spray is less than the amount of alkali metals present in the combustion products. may make up a significant portion of the

As previously mentioned, the coexistence of sulfur and alkali metals, which are always present in trace amounts in petroleum fuels, can cause gas turbines to operate using such fuels at temperatures of 760-927°C (1400-1700'F) or higher. leads to destructive sulfide corrosion when operating.

Sulfidation, also known as hot corrosion, rapidly degrades hot gas passing alloys used in gas turbine nozzles and blades.

This is because Na2so4 produced by the flame or present in the combustion gas chemically attacks the metallic components of the metal, such as chromium and nickel, resulting in the precipitation of small spherical metal sulfides, mainly chromium sulfide. This causes the chromium content of the metal to decrease and destroys the oxidation resistance of the alloy.

Furthermore, it is important to recognize that this sulfide corrosion is independent and independent of the presence of vanadium compounds in the fuel and the corrosion caused by low boiling point vanadates.

Accelerated oxidation and severe exfoliation caused by sulfidation
Relatively short operating periods of several thousand hours can destroy the alloys in such gas turbines.

Paper A. presented at the Gas Turbine Conference in Brussels, Belgium, May 24-28, 1970.
70 GT 24 A. by C, T, Sims. S. M. E. The publication describes the morphological mechanism of sulfidation corrosion of nickel alloys of gas turbines.

The disclosure of this article is hereby incorporated by reference.

In order to prevent destructive sulfidation of this turbine alloy component, S
It is necessary to supply the additive components according to the invention in such a way that the ratio of io2:MgO is large and the weight ratio of Si:Na is greater than 6:1.

Charges according to or proportional to the amount of vanadium and alkali metals in the combustion products and SiO2:MgO
Using the additives of the invention in ratios, the amount of alkali metals in the combustion products can be substantially increased without any particular negative effects,
For example up to 20 ppm by weight and more than 50
It can be up to ppm by weight or more.

This has substantial economic benefits. If anything, it is an all-important cost factor.

This is because the need for substantial removal of alkali metals from the fuel and/or combustion air and water injected to reduce nitrogen oxides is reduced or eliminated.

The use of the combination of magnesium and silicon additives according to the present invention not only overcomes the serious problem of sulfide corrosion in high temperature gas turbine operations where the use of high grade fuels is recommended, but the use of this additive also makes it possible to Substantially lower grade fuels can be used to operate the turbine.

Additive and fuel compositions according to the invention may also contain other additives known to have beneficial effects in certain fuels.

For example, manganese, barium or iron for combustion improvement and/or smoke suppression, and boron as a microbicide and small amounts of other substances, such as emulsifiers or demulsifiers, may be present depending on the nature of the fuel to be burned. Good too.

Such additive compositions and/or treated fuels contain a source of magnesium and a source of silicon, and/or the combustion effluent gas or hot combustion zone is provided with SiO2 and MgO in the aforementioned ratios and amounts. Additive compositions and treated fuels are included in embodiments of the present invention.

As mentioned above, by carrying out the invention, i.e. by adding additive components to the alkali metal-containing fuel, or by adding in the combustion products a silicon to alkali metal weight ratio of greater than 6:1, preferably 10:1. By combusting the fuel in the presence of an additive component consisting essentially of silicon and magnesium in an amount that yields an amount of 100% of the additive component, the washing away of alkali metals from the fuel is eliminated or reduced.

Additionally, as previously mentioned, when combustion products are used to drive gas turbines in accordance with the present invention, high alkali contents, e.g. Fuel can be combusted under the conditions that appear in objects.

Current A. S. T. M. In , the gas turbine combustion specification sets limits of 5 ppm sodium and 2 ppm vanadium for GTI, GT2 and GT3 fuels that are burned without the need for corrosion or ash deposition control additives. .

Although this fuel specification was established by the turbine manufacturer, industrial experience has shown that even fuels containing relatively low levels of these contaminants, which were previously considered to be acceptable contaminant levels, are completely Not acceptable, 760°C (1
It has been shown to rapidly destroy turbine blades operated at metal temperatures above 400°C.

By using a fuel composition and combusting a fuel in accordance with the present invention, these difficulties are avoided.

Furthermore, as previously mentioned, the present invention avoids washing the sodium-containing stings with water to substantially remove the alkaline content.

According to the invention, a relatively simple operation can be used which consists of settling out the water contained in the fuel and substantially separating it from the fuel, with a short and reasonable fuel retention storage period.

Such operations allow the removal of a substantial portion of the seawater or brine solutions normally present in the fuel, and, if necessary, P-filtration or centrifugation of the fuel avoids high and variable concentrations of sodium; The sodium in such fuels is reduced to a manageable sodium concentration in the present invention of about 10-20 ppm.

As mentioned above, according to the invention, a high content of sodium in the combustion products entering the turbine via seawater salts entrained in the combustion air can be tolerated, and if water injection is adopted, desorption is possible. Use water in the turbine without resorting to costly pre-treatments such as ionization, even if less pure water sources are used, as long as the sodium level in the hot combustion products does not exceed a maximum of about 20-50 ppm. metal contaminants can be essentially removed prior to treatment.

According to the present invention, the sodium content in the fuel or combustion products entering the turbine need not be reduced to negligible levels as long as the additive components of the present invention are present during combustion of the fuel.

This discovery is of great commercial importance and value.

EXAMPLE 1 Tests were conducted to demonstrate the practice of the present invention, and in particular the utility of adding certain component combinations of the present invention to high-sodium fuels.

Several tests simulating conditions to which real gas turbine blades are exposed were performed on metal samples using special equipment.

This special device was installed between November 30, 1970 and December 3, 1970.
The American Society of Mechanical Engineers (The American Society of Mechanical Engineers) was held in New York City, New York, USA on the
Society of Mechanical Engineering
``Laboratory Evaluation Method for High Temperature Corrosion Resistance of Gas Turbine Alloys'' presented at the annual meeting of
Tory Procedures for Evalua
ting High-Temperature Cor
Resistance of Gas
A. Turbinalloys) J. S. M.
E. It is described in the paper Paver A70-WA/CD 2.

The metal samples tested were Co,
Nickel alloy Udim containing Cr, AI and Ti
et500 and a cobalt alloy X-45 containing Cu1Ni and W.

The fuel used in the test was a fuel oil containing varying amounts of sodium ranging from 1.5 to 20 ppm and varying amounts of vanadium ranging from 2 to 20 ppm.

The specific ingredients of the invention were added at varying ratios of magnesium to vanadium and silicon to sodium.

Additives consisting essentially of a silicon compound and a magnesium compound forming SiO2 and MgO at the combustion temperature, magnesium sulfonate containing 12% by weight MgO and a silicone polymer containing approximately 60% by weight SiO2 at the boiling point. It was used in dissolved form in an aromatic petroleum fraction with a temperature above about 232°C (450'F).

Mg/V and SiQ with additives and fuels listed in Table I
They were combined to give a ratio of 2/MgO.

The test results are listed in Table ■.

The test was conducted for approximately 150 hours at approximately 3 atmospheres using a combustion gas temperature of 871°C (1600'F).

The results of these tests are listed in Table I.

As is clear from the test data, 871°C (1600'
F), the fuel contains a relatively small amount of ash, e.g.
Even in the presence of pm vanadium and sodium, the weight loss and bushy corrosion of the alloy samples increases considerably, whereas when a distilled ash-free fuel is burned under the same test conditions. Only normal high temperature oxidation occurs.

When a magnesium additive is added to a relatively high vanadium content fuel at a Mg/V weight ratio of 3/1, the
Corrosion of vanadium at temperatures (500'F) is inhibited by low sodium content in the fuel.

However, at high sodium concentrations in the fuel,
Rapid destruction of the gold-bearing metal occurs even in the presence of magnesium at the conventionally recommended Mg/V weight ratio of 3/1.

In contrast to the ineffectiveness shown with magnesium additive ingredients,
The combination of additive components of the present invention is made such that Na/V is 1 containing 20 ppm vanadium and 20 ppm sodium.
When used with a fuel that is nickel, the sulfidation attack is safely prevented under the same conditions, and the weight loss of the metal alloy sample is reduced to a level approaching the value shown for the case without ash. In the case of base alloy U500, corrosion is reduced compared to fuels containing 2 ppm vanadium and 2 ppm sodium.

As previous tests have shown, 2 ppm of V and Na is the maximum concentration of metals allowed in fuel used for high temperature turbine operation without additives.

However, the most important benefit derived from the use of the additive compositions of the present invention is as a means of avoiding sulfidation of metal alloys used in the nozzles and blades of turbines operating at temperatures above about 760°C (below 1400°C). Sulfidation is suppressed as shown when using fuel containing 20 ppm sodium, which is 20 times the maximum sodium content of 1 ppm specified by most turbine manufacturers.

As is clear from the test results listed in Table I, the use of the specific combination of additive components according to the present invention allows the fuel to be combusted in the presence of this combination of additive components to the extent that it is possible to achieve A much higher content of alkali metals, such as sodium, than previously thought may be present in the fuel, thereby avoiding destructive sulfidation and excessive corrosion of the blades.

Example 2 Device and alloy used in Example 1 Udimet5 0 0
The test was conducted using

The fuel used in the test was &2 fuel oil containing 50 ppm vanadium and no sodium, and the test was carried out at a temperature of 815° (below 1500°) of the sample at 3 atm.
I did it for 10 hours.

In separate tests, additive components providing sources of magnesium alone, silicon alone, and three different silicon/magnesium mixtures were added to the oil.

A test fuel providing the sole source of magnesium was made by adding a dispersion of Mg(OH)2 in paraffin oil to the oil, and this dispersion contained 31% MgO2 by weight.

Is the test fuel that supplies only a silicon source with a high boiling point ≥? A solution of the silicone polymer in an aromatic solvent (a methylnaphthalene fraction with a boiling point of 232° to 371°C (450° to 700'F)) was added to the oil, and the solution contained 23% by weight of SiO2. It contained.

Test fuels providing both magnesium and silicon sources were made using solutions of organomagnesium and silicon sources in high boiling aromatic solvents.

More specifically, a magnesium sulfonate containing 12% by weight MgO and a silicone polymer containing 60% by weight SiO are shown in the table below.

Combined equivalents of SiO to give the ratio S i 02 / MgO
2 and MgO in an amount of 14-20% by weight.
It was dissolved in a methylnaphthalene fraction having a boiling point of 71°C (450° to 700°F).

After 10 hours of testing, the samples were examined for corrosion and ash deposit properties.

The results are shown in Table ■.

These data clearly demonstrate the synergistic effect of the additive components of the S i /Mg combination in controlling both corrosion and ash deposition.

The soft, weak deposits that form when using the Si/Mg additive are clearly improved over the hard, brittle deposits when using the additive that supplies only magnesium.

It is the large build-up of deposits, characteristic of the use of magnesium-containing, silicon-free additive components, that reduces the power output of the gas turbine and limits its use in base-load operation.

However, the ratio of SiO2/MgO of the additive component is 2:
A thickness greater than 1 has the particular benefit of reducing the amount of soft, weak deposits and allowing base load type operation.

As alloy samples, other nickel-based "superalloys" disclosed in the publications mentioned in Example 1, lnco
Similar results were obtained in other comparative tests using 713C, 1nco738, and Udimet 710 and the cobalt-based superalloy JX-45.

Example 3 To evaluate the effect of increasing the proportion of silicon in the magnesium-silicon fuel oil additive component in reducing corrosion of turbine blade alloys by fuel combustion products, No. A test as described in Example 2 was conducted in which 2 fuel oils were burned, and vanadium and sodium were added to give 5 ppm vanadium and 2 ppm sodium.
Several comparative tests were conducted.

The test was conducted at 3 atm for 50 hours, and the sample temperature was 815°C (
1,500 or less).

As an alloy for Turbine Pred, “Udimet5 0
0j, i.e., nickel-based alloys containing substantial amounts of cobalt, chromium, and other components; Another nickel-based alloy containing the components was tested.

Control tests were carried out without additives, while tests were conducted with additives at a Mg:V ratio of 3:1 and with additives with different amounts of silica at a Si02:MgO ratio of 1.
．． The ratios were 5:1, 3:1 and 6:1.

In these tests, organomagnesium sources i.e.
magnesium sulfonate containing 2% by weight MgO,
and an organosilicon, i.e. a silicone polymer containing 60 wt. Si0 shown in the table
Combined equivalents of SiO2 and Mg to give a ratio of 2/MgO
O was dissolved in an amount of 14-20% by weight.

Expressed in weight ratio used and mg/cm.

Pertinent data regarding the observed corrosion (weight loss) are shown in Table ■.

These results show that corrosion varies considerably with changes in alloy composition, and that on average a 2:1 ratio of silicon to sodium reduces corrosion by about 50% (Udime
For t7 10, the decrease is slightly less than 50%, and Ud
It can be seen that for imet500 the reduction is substantially greater than 50%).

The very low corrosion and slope of the curve in the Si2Na range of 5=1 to 6:1 suggests that some further increases in the Si:Na ratio may be beneficial for the alloy.

Next, additive compositions or formulations according to the invention are shown.

One formulation includes about 54% by weight of a petroleum hydrocarbon fraction such as aromatic petroleum fraction, about 25% by weight of an organic silicon-containing compound such as silicone, and about 21% by weight of an organic magnesium-containing compound such as petroleum sulfonic acid. of magnesium salt, provides a SiO2/MgO weight ratio of 6:1, and has a total metal oxide content of about 17.5% by weight.

The formulation is useful as an additive in the combustion of normally liquid distillate fuels for gas turbines, such as normally liquid distillate oil burners.

Other formulations useful in the combustion of vanadium-containing fuels for gas turbines, such as vanadium-containing liquid petroleum fuels, include, according to the present invention, 34% by weight liquid hydrocarbon or petroleum fraction, 25% by weight organosilicon-containing compounds and 41
% by weight of a magnesium-containing organic compound, the additive composition has a Si02/MgO weight ratio of 3:1 and a weight ratio of about 20
% total metal oxide concentration by weight.

Various modifications and variations of the additive composition according to the invention, fuels containing the same, and methods of burning fuel in the presence of the additive composition will be apparent to those skilled in the art from the foregoing description.

Claims (1)

[Claims] 1. A fuel composition for use in gas turbines operating at temperatures above about 760° C. (below 1400° C.), the content of one or both of alkali metals and vanadium being 2 pp by weight.
a primary amount of combustible fuel greater than the resulting fuel consists essentially of a silicon compound and a magnesium compound, the ratio of these compounds being such that it provides a combined equivalent of SiO2 and MgO with a SiO2:MgO ratio greater than 2=1; The amount of the additive component incorporated into the fuel composition is such that the weight ratio of silicon to alkali metal in the fuel composition or in the produced effluent combustion gas is greater than 6:1 and/or the weight ratio of magnesium to vanadium in the fuel composition is greater than 6:1. A fuel composition characterized in that the ratio is greater than 2:1.