JP2008520765A - Solid hydrocarbon fuel supply direct flame burner, furnace, open flame additive and related method - Google Patents

Abstract

  The present invention relates to the field of fuel additives for hydrocarbon fuels that act to increase efficiency and / or reduce pollution. The fuel additive is a phosphorus-containing composition that can be added to the surface of the fuel for combustion with a solid hydrocarbon fuel in an open flame burner, furnace or open flame.

Description

[Citation of related application]
This application claims priority to US Provisional Patent Application 60 / 628,002, filed November 15, 2004.

  The present invention relates to the field of fuel additives, particularly solid hydrocarbon fuel feed burners, furnaces and open flame additives to increase efficiency and / or reduce undesirable emissions such as pollutants.

Solid hydrocarbon fuels such as coal have long been used for fuel burners, furnaces and open flames. Coal, especially lignite and other low BTU coals, do not burn very efficiently and generate undesirable emissions including significant smoke, NO _x , SO ₂ , particulate matter, and other CO. Chemical compounds have been used as combustion improvers that increase the combustion efficiency of solid fuels. However, many of these additives contain heavy metal elements such as manganese, zinc, iron, copper, cerium, calcium and barium. Some of these elements, when burned, can produce heavy metal solid residues, which are highly undesirable.

Fuel additives including combustion catalysts that reduce smoke and particulate emissions from coal-fired burners, furnaces and other open flame applications would be advantageous. Fuel additives that increase efficiency and / or reduce pollutants over solid fuels, including low quality coals such as coal and other lignites used in these applications would be particularly advantageous. It would also be advantageous to reduce smoke, particulate emissions and nitrogen containing emissions from fuel applications. In addition to NO _x reduction, the reduction or removal of other toxic contaminants such as SO ₂ is also highly desirable. Additives that do not result in the formation of heavy metal precipitates and residues during the combustion process would be desirable.

  The present invention includes fuel additives and methods of using the additives in connection with solid fuels such as coal.

The fuel additive of the present invention includes a phosphorous-containing parent solution containing [Y] _x H ₂ PO ₄ , [Y] _{x +} HPO ₄ (where [Y] is a cation). Y need not be the same cation in both salt compounds. The cation portion of the salt component may be any cation, but potassium is a preferred cation. In this case, the preferred components will be KH ₂ PO ₄ , K ₂ HPO ₄ . These salts are at least partially dispersed in water or other suitable solvent to form a phosphorus-containing parent solution. Advantageously, the fuel additive in this embodiment is an ammonia-free solution. One preferred embodiment involves adding these components in the presence of water to produce a phosphorus-containing parent solution as a hydrophilic solution. The water acts as the solvent. Other preferred parent solution solvents include alcohol. Another group of preferred cations would be alkali metals or Group 1A elements. Although NH ₄ used as Y produces a fuel additive that enhances fuel performance, it may be preferable to avoid ammonium and therefore ammonia as well.

Another preferred embodiment of the phosphorous-containing parent solution includes adding [NH ₄ ] ₂ HPO ₄ to [Y] _x H ₂ PO ₄ , [Y] _{x +} HPO ₄ and water. Yet another embodiment is such that the solution contains [Y] _x H ₂ PO ₄ , [Y] _{x +} HPO ₄ , [NH ₄ ] ₂ HPO ₄ , NH ₄ C ₂ H ₃ O ₂ and water. ₄ C ₂ H ₃ O ₂ (wherein _{C 2 H} 3 _O 2 ^- ions is the acetate groups), including the addition of. When producing a fuel additive using an ammonium compound defined as a compound containing an NH _x group, the nitrogen in the solution is essentially all in the form of ammonium ions. There is at most a very small amount of free ammonia. In a preferred embodiment, the solution has a pH between about 6.0 and 8.0.

Another preferred embodiment of the phosphorous-containing parent solution includes adding [Y] _x PO ₄ to [Y] _x H ₂ PO ₄ and [Y] _{x +} HPO ₄ .

Orthophosphoric acid, also called phosphoric acid, has been described, which includes pyrophosphoric acid, a condensed analog of orthophosphoric acid. The difference is that PO ₄ ³⁻ becomes P ₂ O ₇ ²⁻ or other condensed phosphates through the process of condensing orthophosphoric acid. Thus, [Y] _x H ₂ PO ₄ and [Y] _{x +} HPO ₄ are precursors of pyrophosphate. Therefore, the use of pyrophosphate and other condensed forms is included within the definition of orthophosphate form.

  In the case of solid fuels such as coal, the phosphorus-containing parent solution can be applied directly to the solid fuel by any method capable of producing a uniform coating, such as spraying, dipping, suspending, and the like. In many industries, coal is sprayed with water to prevent dust formation during the grinding process before combustion. The water spray can advantageously include a phosphorous-containing parent solution. However, other methods known in the art for contacting aqueous solutions with solid hydrocarbons can also be used.

The fuel additive of the present invention is useful for enhancing combustion so that more complete combustion of combustion to CO ₂ and H ₂ O is achieved compared to combustion of solid fuel without fuel additive It is. The result is a reduction in partial combustion products as well as NO _x and thereby an increase in fuel efficiency.

The fuel additive is used by adding the additive to the fuel in an amount sufficient to increase fuel efficiency or reduce pollutants. The terms enhancement and combustion enhancement refer to any of these effects. Reduction examples pollutants is a reduction of the NO _x solid fuel direct fired burner, in the exhaust gas produced from the furnace or open flame. Advantageously, both these effects are observed with the addition of the fuel additive of the present invention. A preferred embodiment involves adding between about 50 ppm and 150 ppm phosphorus on the fuel by adding a fuel additive. Increased amounts of phosphorus are equally effective.

  A solid hydrocarbon fuel in a combustion system comprising the steps of supplying the fuel additive described above to a solid hydrocarbon fuel in an amount effective to enhance fuel performance and combusting the solid hydrocarbon fuel with the fuel additive. A method for improving the fuel performance is included in the present invention. The combustion scheme may be any means known to those skilled in the art for burning solid hydrocarbons. The combustion scheme can include one or more open flame burners, furnaces, fluidized beds, open flames, and the like. In a preferred embodiment, the method is used with a solid hydrocarbon fuel. The result of adding the additive to the solid hydrocarbon fuel is an improved fuel having a substantial amount of solid hydrocarbon fuel suitable for combustion and a quantity of fuel additive that can be used to enhance combustion. Preferably, the improved fuel contains phosphorus in an amount that can be used to reduce emissions from combustion of the improved fuel as compared to combustion of a hydrocarbon fuel without a fuel additive. More preferably, the improved fuel contains between about 1 ppm and 150 ppm phosphorus by weight. Another preferred embodiment is between about 1 ppm and 80 ppm by weight.

  In fluidized bed applications, the fuel additive is introduced during the combustion process by means known in the art onto coal prior to combustion or onto fly ash prior to secondary combustion, or fluidized bed or It can be injected into a partially fluidized bed.

An alternative aspect of the present invention includes a method for improving the fuel performance of a hydrocarbon fuel in a combustion mode, comprising adding a chemical additive composition to the hydrocarbon fuel in an amount effective to enhance fuel performance. It is. The chemical additive composition comprises (i) a reactive NH ₂ group source in an aqueous medium with the following substances: (A) an alkali metal hydroxide to raise the pH of the solution above 12 to form an aqueous ammonium / alkali metal hydroxide, or 2. (B) prepared by lowering the pH of the solution to about 0 and mixing with one of the phosphoric acid sources to form an acidic ammonium mixture.
3. The next step combines the intermediate solution of step (ia) with a phosphoric acid source at a rate sufficient to cause a highly exothermic reaction, or the solution of (ib) is subjected to the hydroxylation. Including compounding with things. This results in reactive NH ₂ groups being included in the solution during the formation of the chemically additive composition. This chemically added composition is added to the hydrocarbon fuel.

  The parent solution or chemical additive composition of the present invention can be added directly onto the solid hydrocarbon combustion fuel.

  The improved fuel comprises a substantial amount of solid fuel suitable for combustion and a phosphorous-containing parent solution or chemical additive composition in an amount sufficient to reduce emissions or increase efficiency upon combustion of the improved fuel. Generate when combined.

A composition of phosphoric acid, alkali metal hydroxide and reactive NH ₂ source has been explored in US Pat. No. 5,540,788 for the creation of conversion surfaces, the disclosure of which is hereby incorporated herein by reference. Cited in and incorporated by reference. The present invention involves the use of a conversion surface composition as a solid fuel additive. In one embodiment, the fuel additive is a chemical additive composition for improving hydrocarbon fuels, wherein the chemical additive composition has the composition disclosed in US Pat. No. 5,540,788. Have. This aspect is unique in the use of a reactive NH ₂ source, but it can be advantageous depending on environmental conditions. Chemical compositions that contain reactive NH ₂ groups have some advantages, but may have free ammonia present. Various other embodiments of the fuel additive of the present invention avoid the production of free ammonia and the problems associated therewith.

[Detailed explanation]
The fuel additive of the present invention is believed to perform gas phase conversion of hydrocarbon fuel to achieve more complete combustion to CO ₂ and H ₂ O in the process. Preferably, the fuel additive is supplied as a hydrophilic solution that can be added directly to the surface of the solid fuel. As long as a fairly uniform dispersion is obtained on the solid surface, the mechanism of addition of the hydrophilic solution to the solid surface is not critical. In some cases, it may be advantageous to include a dispersant, surfactant, or other surfactant to help provide a uniform dispersion of the additive on the solid surface. In these cases, it is conventional practice to dissolve, disperse or emulsify the surfactant additive in the parent solution. However, it is also conceivable to pre-coat the solid surface with a surfactant. By performing tests using infrared and other test techniques, a reduction in CO from the exhaust gas due to combustion of the solid hydrocarbon fuel using the fuel additive of the present invention is confirmed.

  The present invention includes the use of fuel additives in open flame burners, furnaces and open flames. This is considered particularly valuable for burners and furnaces using low BTU and / or high sulfur coal. Use in the burner, furnace or open flame appears to provide a combustion advantage that allows for the reduction of particulates and other emissions. Since the method of the present invention is effective at the high temperatures produced as part of the combustion process, the fuel additive is included in the open flame along with the fuel. Although there are too many examples of the use of coal, the use of digitized coal in power plants is particularly advantageous because the quality of the coal can vary significantly, especially with respect to BTU and sulfur pigments.

An example of a preferred formulation of the present invention is the following ratio: 1.597 moles KH ₂ PO ₄ , 0.693 moles K ₂ HPO ₄ , 0.315 moles [NH ₄ ] ₂ HPO ₄ and water. including. The pH of the solution can be adjusted by skillfully manipulating the ratio of these components. By skillfully manipulating the resulting H ₂ PO ₄ ^- and HPO ₄ ^2- ion ratio, the solution can be prepared in a preferred pH range of about 6.0 to about 8.0.

In a preferred embodiment, a phosphorous-containing parent solution is formed from KH ₂ PO ₄ , K ₂ HPO ₄ , [NH ₄ ] ₂ HPO ₄ and water. An example of a preferred embodiment is 0.3% by weight phosphorus in the solution, which can be added directly to the solid fuel surface in any suitable manner. When added to the fuel surface, the phosphorus content ranges from 5 to 100 ppb and can still be effective. Preferably 1-250 ppm of phosphorus is used on the fuel. Higher amounts are also effective. More preferably, 1 to 150 ppm phosphorus by weight per total solid fuel weight is used on the solid fuel surface. Another preferred embodiment is 1-80 ppm phosphorus.

  An example of an alternative embodiment of a phosphorus-containing parent solution used on solid fuels includes mixing about 2.6 moles (M) of normal phosphate with alkali metal and ammonium cations, the resulting hydrophilic solution being Has a pH of 7 at ambient temperature. The hydrophilic solution thus produced, when added to a solid fuel, acts to reduce the release of contaminant molecules under normal operating conditions. An example of an alternative embodiment includes the use of phosphoric acid, potassium hydroxide, ammonium hydroxide in water. Acetic acid can also be added. The amounts of the components can be adjusted to reach the desired pH.

1. A phosphoric acid / acetic acid solution [H ₃ PO ₄ / HOAc solution] is prepared. For this experiment, the H ₃ PO ₄ / HOAc solution is about 90 mol% H ₃ PO ₄ and 10 mol% HOAc.
2. Prepare deionized water for reaction.
3. Add 2,736.39 pounds of potassium hydroxide to the water.
4). To this aqueous solution is added 1,315.14 pounds of ammonium hydroxide (29%).
5. To the resulting solution was added to _H 3 _PO 4 / HOAc solution allows for the reaction.
6). After the reaction, the pH is adjusted to a pH of about 7.0 using acetic acid. The resulting reaction product is useful as a chemical additive to improve hydrocarbon fuels.

By using the fuel additive described in Example 1 in combination with a 300 mesh high sulfur ohio composite coal containing 3.4% S, in the exhaust gas compared to coal without fuel additive. 39% reduction in CO emissions, 52% reduction in SO _2, reduction of NO _x, and 10% reduction in fine particles are provided. The coal was impregnated with the hydrophilic solution before combustion so that the resulting P concentration (based on the total weight of the coal) was 80 ppm.

Ingredients Pound Weight ratio
-------------------- ---------- ---------
Phosphoric acid 2,583 0.25
Potassium hydroxide 2,736 0.26
Ammonium hydroxide 1,315 0.13
Acetic acid 672 0.06
Deionized water 3,105 0.30
==================== ============ =========
Total phosphorus-containing parent solution 10,411 1.00

  In an alternative embodiment, the solvent is limited by the solubility or dispersibility of the salt in the solvent and the volatility of the solvent. For example, the salts are preferably dispersed in the solvent, but the solvent is volatile so that it can evaporate without affecting flammability during the combustion process.

While the invention has been shown or described only in some of its forms, it will be apparent to those skilled in the art that the invention is not so limited and that various changes may be made without departing from the scope of the invention. It's a nasty habit. For example, [Y] _x H ₂ PO ₄ , [Y] _{x +} HPO ₄ is also [Y] _x [H ₂ PO ₄ ] _z , [Y] _{x +} [HPO ₄ ] _z , where x and z vary. Which is an integer to obtain).

Claims (16)

A method for improving the fuel performance of a hydrocarbon fuel in a combustion system having an open flame burner, a furnace or an open flame, wherein the fuel additive or chemical additive composition is used as a fuel for the open flame burner, furnace or open flame Providing the hydrocarbon fuel in an amount effective to enhance performance and combusting the hydrocarbon fuel with the fuel additive or chemical additive composition, the fuel additive comprising a salt mixture and a dispersion And wherein the salt mixture comprises [Y] _x H ₂ PO ₄ and [Y] _{x +} HPO ₄ , where [Y] is a cation, and the dispersion fluid contains at least the salt in the dispersion fluid. Contaminants in exhaust gas that can be used to maintain a partially dispersed solution to produce a solution, where the improved fuel performance results from increased fuel efficiency or combustion of the fuel and the fuel additive Measured by reduction in emissions An ability, and said chemical additive composition is phosphoric acid source, an alkali metal hydroxide, comprising the reaction product resulting from the mixing of ammonium hydroxide and water, said fuel performance enhancement methods.   2. The fuel performance enhancing method of claim 1 wherein the fuel additive is free of ammonia. The method of claim 1, wherein the fuel additive further comprises [NH ₄ ] ₂ HPO ₄ . The method for improving fuel performance according to claim 1 or 3, wherein the fuel additive further comprises NH ₄ C ₂ H ₃ O ₂ (wherein C ₂ H ₃ O ₂ is an acetate radical).   A method for improving fuel performance according to any one of the preceding claims, wherein the pH of the solution is between about 6.0 and 8.0.   A method for improving fuel performance according to any one of the preceding claims, wherein phosphorus is present in the hydrocarbon fuel in an amount between about 1 ppm and 150 ppm by weight.   7. According to any one of the preceding claims, wherein the hydrocarbon fuel is a solid hydrocarbon fuel, preferentially coal, more preferentially high sulfur coal, most preferentially high sulfur low BTU coal. Fuel performance improvement method.   The method for improving fuel performance according to any one of claims 1 to 7, wherein the chemical additive composition further comprises acetic acid. A salt [Y] _x H ₂ PO ₄ and [Y] _{x +} HPO ₄ (where [Y] is a cation) are mixed in a solvent to at least partially disperse the salt in the solvent and solid carbonized Improved combustion of hydrocarbon fuels, including the step of generating a phosphorous-containing parent solution that can be used to improve combustion when added to an open flame burner, furnace or open flame in the presence of hydrogen fuel and burned A method for producing a fuel additive for causing A fuel additive comprising a salt mixture and a dispersion fluid, the salt mixture comprising [Y] _x H ₂ PO ₄ and [Y] _{x +} HPO ₄ , wherein [Y] is a cation. Can be used to maintain the salt at least partially dispersed in the dispersion fluid to form a solution, and the fuel additive can be used as a fuel in an open flame burner, furnace or open flame. Contaminant emissions in exhaust gases that can be used to improve combustion when placed in contact and burned, the increased combustion resulting from increased fuel efficiency or combustion of the fuel and the fuel additive A fuel additive as described above, which is measurable by a decrease in amount. The fuel additive of claim 10 further comprising [NH ₄ ] ₂ HPO ₄ . The fuel additive according to claim 10 or 11, further comprising NH ₄ C ₂ H ₃ O ₂ , wherein C ₂ H ₃ O ₂ is an acetate radical.   11. The fuel additive of claim 10 or any claim dependent thereon, wherein the pH of the solution is between about 6.0 and 8.0.   An improved fuel comprising a substantial amount of solid fuel suitable for combustion and an amount of the fuel additive of claim 10 usable to enhance combustion.   15. The improved fuel of claim 14, wherein phosphorus is present in the hydrocarbon fuel in an amount between about 1 ppm and 150 ppm by weight.   16. The improved fuel of claim 14 or 15, wherein the amount of fuel additive is an amount that can be used to reduce emissions from improved fuel combustion as compared to combustion of hydrocarbon fuel without fuel additive.