JP2005519165A - Fischer-Tropsch derived hydrocarbon containing low emission fuel emulsion - Google Patents

Abstract

An emulsion of hydrocarbons and water, wherein the hydrocarbons are preferably Fischer-Tropsch derived hydrocarbon fuels, and emulsions in which most of the hydrocarbons have a particle size of 1 μm or less reduce particulate matter emissions during combustion. The

Description

  The present invention relates to an improved fuel having the characteristics of reduced particulate matter emissions. More particularly, the invention relates to a fuel in the form of a hydrocarbon-in-water emulsion.

Hydrocarbon emulsions in water have many potential uses, such as in internal combustion engines and as fuels for heating. In fact, many studies suggest that combustion of hydrocarbon-in-water emulsions has the advantage of reducing the nitrogen oxide emissions normally associated with hydrocarbon combustion. Emulsions are believed to reduce nitrogen oxide (NO _x ) emissions due to a decrease in peak flame temperature during their combustion. However, lower flame temperatures are often accompanied by increased particulate matter (Pm) emissions. This phenomenon is known as the Pm-NO _x tradeoff and is thought to limit the improvements that can be made to diesel emissions.

US Pat. No. 5,348,982 US Pat. No. 5,545,674 U.S. Pat. No. 4,568,663 US Pat. No. 5,378,348 US Pat. No. 5,807,413 US Pat. No. 5,405,439 US Pat. No. 5,236,624 US Pat. No. 4,832,747

  In recent years, emissions regulations (including particulate matter emissions) have become more stringent. Accordingly, it is an object of the present invention to provide a method for more efficiently controlling particulate matter emissions without adversely affecting the presently achievable reduced levels of nitrogen oxide emissions shown for emulsified fuels. Is to develop.

  In the case of diesel fuel engines, the reduction of particulate matter emissions is particularly important. Accordingly, another object of the present invention is to provide an improved diesel fuel having the characteristics of reduced particulate matter emissions.

  According to the present invention, an emulsion of hydrocarbon and water, wherein the hydrocarbon is a Fischer-Tropsch (FT) derived hydrocarbon fuel or a mixture of FT fuel and conventional hydrocarbon fuel, the majority of the hydrocarbons Reduced particulate discharge is achieved with emulsions having a particle size of 1 μm or less. Preferably, the emulsion is a hydrocarbon-in-water emulsion.

  In a particularly preferred embodiment of the invention, the hydrocarbon is an FT derived hydrocarbon boiling in the range of diesel fuel.

  These and other embodiments will be apparent upon reading the following detailed description of the invention.

  The emulsion of the present invention comprises as a hydrocarbon a Fischer-Tropsch derived hydrocarbon fuel or a mixture of FT fuel and conventional hydrocarbon fuel. Preferably, the hydrocarbon is an FT derived fuel.

  As is well known in the art, the Fischer-Tropsch process involves reacting a hydrogen / carbon monoxide containing feedstock in the presence of a suitable catalyst to produce primarily normal paraffin synthetic crude oil. The process is described in, for example, US Pat. Each of which is incorporated herein by reference.

  The hydrocarbon fuel produced by the Fischer-Tropsch process may be separated from the product crude oil by standard distillation techniques. In addition, however, the waxy component of crude oil may be converted to fuel by known techniques such as hydrogenation, hydroisomerization, hydrocracking. Examples of these processes can be found in US Pat. This is incorporated herein by reference.

In the context of embodiments of the present invention, a Fischer - Tropsch derived hydrocarbon fuels, Fischer - direct liquid product from Tropsch process (C 5 _+), converted Fischer - Tropsch product, any mixtures thereof May be included. Accordingly, Fischer-Tropsch products boiling in the range of about 25 to about 450 ° C are suitable. These fuels include those shown in Patent Document 5. This patent is incorporated herein by reference. Also included are the more common Fischer-Tropsch products. For example, it boils at about 140 to about 370 ° C, preferably about 160 to about 350 ° C.

  The water of the emulsions of the present invention may be those typically used to form fuel emulsions, such as tap water, distilled water or deionized water. In one embodiment, water from the Fischer-Tropsch process constitutes the continuous phase of the emulsion. Fischer-Tropsch process water typically contains no more than about 2% by weight of oxygenates. A typical composition is shown in Table 1 below.

  The amount of water used to form the emulsion can vary over a wide range. For example, the Fischer-Tropsch hydrocarbon fuel / water volume ratio may be from about 95: 5 to about 60:40.

  The emulsions of the present invention also include a nonionic surfactant or a mixture of nonionic surfactants. Suitable types of nonionic surfactants include ethoxylated alcohols, ethoxylated alkylphenols, ethoxylated carboxylic acid esters, glycerin esters, sorbitan esters, and the like. Generally, the nonionic surfactant has an HLB of 5-30, preferably 8-15. Of suitable surfactants, ethoxylated alkylphenols having about 5 to about 30 moles, preferably 10 to 15 moles of ethylene oxide groups are worthy of special mention.

  The amount of surfactant or mixture thereof in the emulsion ranges from about 0.05 to about 5.0% by weight, based on the total weight of hydrocarbon and water. Typically from 0.05 to about 2% by weight.

  The emulsion composition of the present invention may contain a small but effective amount of conventional additives (emulsion stabilizer, antioxidant, etc.). Where the fuel is diesel fuel, the fuel may also contain general amounts of diesel fuel additives (cetane improvers, detergents, heat stabilizers, etc.).

  As is known in the art, an emulsion may be formed by any number of procedures. The heart of all these is to provide sufficient shear of the ingredients for emulsification. In practicing the present invention, fuel is added to a mixture of water and surfactant and sheared under conditions sufficient to produce most hydrocarbon particles having a size of 1 μm or less. In other words, the particles are substantially uniform in size. That is, the size of about 0.1 to about 1.0 μm exceeds 50%. It has been empirically shown that significant shear results in the formation of a “gel”. The shear is therefore less than that which produces a gel.

  In order to achieve the required shear, it is particularly preferable to use one or more static mixers (for example, those described in Patent Document 6, Patent Document 7 and Patent Document 8). In general, one or more mixers are used, and the mixers are not of the same size (length, diameter, number of internal elements). Rather, the number, size and elements are selected to adjust the mixing efficiency and emulsion particle size. In practicing the present invention, a combination of static mixers is provided to provide sufficient shear of hydrocarbons and water to produce emulsions with a particle size of 1 μm or less, and less than that which produces “gels”. Select.

  A schematic diagram of one arrangement of a static mixer suitable for carrying out the emulsification of the present invention is shown in the accompanying drawings. As shown, each of the six mixers has different dimensions. Obviously, different mixer components and sizes may be used as long as the required shear is achieved. The dimensions of the mixer shown are shown in Table 2 below.

In the arrangement shown in the drawing, water and surfactant solution are fed to mixer 1 via line 7 and Fischer-Tropsch derived hydrocarbon fuel is fed to line 1 via line 8. The product of each mixer is continuously fed to the next mixer in the row (eg, the product of mixer 1 is fed to mixer 2, the product of mixer 2 is fed to mixer 3, etc.). The emulsion leaving the mixer 6 via line 9 is mostly less than 1 μm in particle size. The emulsion when the Fischer-Tropsch fuel is a diesel fuel has a viscosity of about 50-200 mm ² / sec at 20 ° C.

Comparative Example 1
3000 g of nonionic surfactant (ethoxylated nonylphenol having 10 moles of ethylene oxide groups) was added to 9700 g of water and fed through mixers 1-4 as shown in the figure. Fischer-Tropsch diesel fuel containing 90 ⁺ % C ₆ -C ₁₆ linear paraffins (boiling range: ˜40-300 ° C.) was also fed through four mixers along with water and surfactant. The volume ratio of fuel / water was 70:30. The flow rate of the hydrocarbon was 2650 ml / min, and the flow rate of the aqueous surfactant solution was 1380 ml / min. The temperature was 24 ° C. The product of mixer 4 was not a hydrocarbon-in-water emulsion.

Example 1
The same ingredients and amounts as shown in Comparative Example 1 were fed through mixers 1-6 shown in the drawing. The flow rate and temperature were the same as in Comparative Example 1. In this case, the product of the mixer 6 was a hydrocarbon-in-water emulsion having a density of 0.82 g / cc and a viscosity of 150 mm ² / sec (20 ° C.). The average size of the hydrocarbon particles was 0.7 μm, and the size of less than 1 μm was 95%. This emulsion had a storage stability of over 6 months.

Example 2
A Caterpillar IY540 single cylinder heavy duty research engine was used to compare the performance of the emulsified Fischer-Tropsch fuel of Example 1 with the same non-emulsified Fischer-Tropsch diesel fuel and Swedish Class 1 diesel fuel. Measurements were made under two conditions: low load (1500 rpm, torque 60 Nm and BMEP 3.0 bar) and medium load (1500 rpm, torque 110 Nm and BMEP 5.5 bar).

As is known, Swedish class 1 diesel fuel (also called urban diesel ECI) produces about 10-20% lower NO _{x and} 40-50% particulate matter (Pm) than conventional diesel fuel. Low, standard low emission reference diesel fuel. The specifications for Swedish Class 1 diesel fuel are shown in Table 3.

Non-emulsifying Fischer - Tropsch fuels (FTF) is reduced of the NO _x as compared with conventional diesel fuel 10% to 25%, of reduced 40% to 60% of Pm, have been shown to have excellent emissions performance (See Patent Document 5). Figures 2 and 3 show the relative emission performance of a Fischer-Tropsch fuel and the emulsion of the present invention (Example 1) at low and medium loads relative to Swedish Class 1 diesel fuel.

As can be seen from FIG. 2, the FTF behaves similarly to the Swedish class 1 diesel fuel. The fuel emulsion of the present invention exhibit 22% less NO _x emissions and 53% lower Pm discharged from Swedish Class 1.

  In FIG. 3, the fuel emulsion of the present invention shows a much greater PM reduction (91.5%) than Swedish Class 1 fuel.

In FIGS. 4 and 5, the Pm / NO _x performance of the fuel is plotted against changes in spark timing. As can be seen, when the FTF and Swedish Class 1 fuel, to reduce NO _x emissions was capable of delaying the timing.

1 is a schematic diagram of one arrangement of multiple static mixers used to prepare the emulsion of the present invention. FIG. 2 is a graph comparing the performance of the emulsion of the present invention in a diesel engine (no timing adjustment) with two non-emulsifying fuels. 2 is a graph comparing the performance of the emulsion of the present invention in a diesel engine (no timing adjustment) with two non-emulsifying fuels. It is a graph which compares the performance of the fuel of FIG. 2 with timing adjustment. It is a graph which compares the performance of the fuel of FIG. 3 with timing adjustment.

Claims (12)

A method of reducing particulate matter emissions during combustion of a hydrocarbon fuel comprising the step of burning an emulsion of hydrocarbon fuel and water,
The fuel is a Fischer-Tropsch derived hydrocarbon or a mixture of Fischer-Tropsch fuel and conventional fuel;
The method for reducing particulate matter discharge, wherein most of the hydrocarbons in the emulsion have a particle size of 1 μm or less.   The method of reducing particulate matter discharge according to claim 1, wherein the emulsion is a hydrocarbon-in-water emulsion.   The method of claim 2, wherein the fuel is a Fischer-Tropsch derived fuel.   The method for reducing particulate matter discharge according to claim 3, wherein more than 50% of the hydrocarbon particles are 0.1 to 1.0 μm in size.   The method for reducing particulate matter discharge according to claim 4, wherein the volume ratio of hydrocarbon / water is 95: 5 to 60:40.   6. The method of reducing particulate matter discharge according to claim 5, wherein more than 80% of the hydrocarbon particles are 0.1-1.0 [mu] m in size.   The method of reducing particulate matter emission of claim 6, wherein the Fischer-Tropsch derived hydrocarbon boils in the range of diesel fuel. The method for reducing particulate matter discharge according to claim 7, wherein the emulsion has a viscosity of 50 to 200 mm ² / sec. A method of forming an underwater fuel emulsion in which particulate emissions during combustion are reduced compared to Swedish class 1 diesel fuel, comprising:
Fischer-Tropsch derived hydrocarbons boiling in the range of diesel fuel, water and non-ionic surfactants of HLB 5-30 or mixtures thereof are sufficient to produce a liquid emulsion with the majority of the hydrocarbons having a particle size of 1 μm or less. And the volume ratio of the hydrocarbon / water is 95: 5 to 40:60, and the amount of the nonionic surfactant is the total weight of the hydrocarbon and water. A method of forming a fuel-in-water emulsion, comprising the step of 0.05-5.0 wt% as a reference. A liquid fuel composition comprising an emulsion of Fischer-Tropsch derived fuel in water, wherein most of the fuel in the emulsion has a particle size of 1 μm or less, and the emulsion has a viscosity of greater than 50 mm ² / sec at 20 ° C. Stuff.   The liquid fuel composition according to claim 10, wherein more than 50% of the fuel particles have a particle size of 0.1 to 1.0 μm.   The liquid fuel composition of claim 11, wherein the Fischer-Tropsch derived fuel boils in the range of diesel fuel.

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