FUEL

Abstract

An improved fuel, particularly an improved transport fuel composition is provided. Alternate fuels to traditional oil derived petrol and diesel have been considered particularly for transport purposes. However, there are limitations that have prevented their widespread use. A fuel composition is provided for use in an internal combustion engine comprising an organic carrier fuel having a particulate additive dispersed therein, the particulate additive being a lubricant.

Description

FIELD OF THE INVENTION

The present invention relates to an improved fuel, particularly to an improved transport fuel composition.

BACKGROUND OF THE INVENTION

Alternate fuels to traditional oil derived petrol and diesel have been considered particularly for transport purposes. These include organic fuels such as alcohols for use in spark ignition engines. Dimethyl Ether (DME), Methyl Tert-Butyl Ether (MTBE) and biodiesel have been considered as a potential fuel substitute for diesel as a transportation and power/heat generation fuel for use directly in a compression ignition diesel engine. The modifications necessary to the engine are relatively minor. These fuels have a number of advantages for the use as a diesel substitute including:

• 1. They can be produced from renewable sources. For example methanol can be produced from synthesis gas (syngas) or from organic waste or biomass.
• 2. They have very high engine efficiency and zero greenhouse gas emissions when compared with other renewable fuel sources.
• 3. They have a high oxygen content allowing clean, smokeless combustion and minimal soot formation with near-zero particulate matter emissions.
• 4. DME particularly has a high cetane number compared to diesel allowing a low auto-ignition temperature and good vaporization characteristics.

However, there are limitations that have prevented their widespread use, and these include:

• 1. They typically have a lower viscosity than diesel causing the potential for leakage in larger engine sizes designed for diesel fuel.
• 2. They have a lower lubricity than diesel causing wear in fuel pumps, injectors, cylinders, pistons, and engine heads over time.

SUMMARY OF THE INVENTION

The present invention addresses the above-mentioned deficiencies.

According to the present invention there is a fuel composition for use in an internal combustion engine comprising an organic carrier fuel having a particulate additive dispersed therein, the particulate additive comprising a lubricant.

The fuel composition may be termed a transport fuel.

The present invention provides a new fuel composition that maintains all of the advantages of an organic renewable fuel while improving the lubricity properties to reduce the wear on the engine whilst maintaining the ability for the necessary minor engine modifications to be effective and furthermore provides a renewable and economically viable diesel fuel substitute.

In particular, incorporation of the particulate additive into the carrier fuel has two significant and important effects. A first effect is that the particulate additive comprising a lubricant has the effect of reducing wear in a combustion engine, for example, in the fuel pump, injectors, cylinders, pistons and engine heads over time. This means that existing components of diesel engines can be used without modification for accepting of the fuel composition without detrimental effect to those components.

A second effect is to increase the viscosity of the fuel thereby reducing the issue associated with leakage of existing organic fuels, particularly in larger engine sizes. This reduces the potential for leakage as the increase in viscosity closer to a viscosity of diesel means that small gaps present in an engine originally designed to run on diesel can effectively be plugged through the provision of the particulate additive.

The addition of particulate additives comprising a lubricant to a fuel teaches away from traditional understanding where particulate material within a fuel is minimised, and further any particulate matter is filtered from the fuel before entering the engine due to the detrimental effects such particles have on the engine.

The organic carrier may comprise or include one or more alcohols such as bioethanol or methanol which are particularly suitable for spark ignition engines. Alternatively or in addition the organic carrier fuel may comprise or include ethers such as DME and/or MTBE and/or biodiesel which are particularly suitable for use in compression ignition engines. The organic carrier fuel may comprise pyrolysis oil. With the addition of a particulate additive, preferably biochar, the total acid number of the oil is reduced and the lubrication properties increased, providing an improved and more stable fuel for slow speed compression ignition engines. Such engines may typically be approximately 300 rpm diesel engines.

The particulate additive preferably comprises a graphitic carbon material. The particulate additive preferably has a high graphitic carbon content.

A graphitic carbon material may be produced by carbonisation of a carbon containing material such as waste materials. Examples are biochar, rubbery waste and spent activated carbon amongst others which are carbonised at high temperatures and/or over extended periods of time to maximise carbonisation such that there is a high proportion of graphite structure in the graphitic carbon material.

The term graphitic carbon covers both graphite and semi-graphite, where semi-graphite is a form of graphite having pores therein. Graphitic materials are beneficial as a lubricant particulate additive being an effective lubricant and are easy to break down into particulate form through milling for example.

The particulate additive may be carbon char, and wherein the carbon char may comprise biochar. Biochar is beneficially derived from wood, preferably sawdust and/or woodchips. The carbon char is beneficially obtained from renewable sources. Carbon char may be obtained on a product of pyrolysis under conditions of high temperature and/or long time periods in order to maximise graphitisation. It has been found that even though carbon char contains other components such as ash, the lubricity of the fuel can be improved without negatively affecting the combustion properties of the fuel. Carbon char is also low cost relative to graphite, and is widely available.

The fuel is preferably stored for use in liquid form and the particulate additive is dispersed through the liquid. It will be appreciated that at atmospheric temperature and pressure certain organic carrier fuels such as DME are in gaseous form, and thus must be pressurised for storage and use as a fuel.

The particulate additive may comprise individual particles having a maximum dimension of less than 20 microns. The maximum dimension of the particulate additive is beneficially selected dependent upon the engine into which the fuel is being burned. For example, it has been determined that it is beneficial if the maximum dimension of the particulate additive is 20 microns for large engines that are tolerant to such particle sizes. Such an engine may be of a size that gives a power output in the order of or greater than 5 MW. For smaller engines such as passenger vehicles for example it is beneficial that the maximum particle diameter is less. The maximum particle size dimension may be less than 1 micron, and optionally less than 0.1 microns, and optionally less than 0.01 microns (equivalent to 10 nanometres).

The particulate additive may be milled or otherwise processed to break down larger particle sizes to produce the required particle size.

The particulate additive is preferably present in the organic carrier fuel in the range of 0.1 to 2 wt/%, and more preferably in the range of 0.5 to 1 wt/%. This improves lubricity of the fuel without negatively affecting the combustion properties of the fuel.

Also according to the present invention there is a method of manufacturing a fuel composition for use in an internal combustion engine comprising the steps of combining an organic carrier fuel with a particulate additive such that the particulate additive is dispersed in the organic carrier fuel.

The organic carrier fuel is preferably provided in a vessel, and the particulate additive is preferably injected into the vessel.

The organic carrier fuel is preferably in liquid form when combining with the particulate additive.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only with reference to the accompanying Figures in which:

FIG. 1 is a schematic representation of pressurised fuel composition according to an exemplary embodiment of the present invention provided in a fuel tank.

FIG. 2 is a flow diagram of the process for manufacturing a fuel composition according to an exemplary embodiment.

DETAILED DESCRIPTION OF THE INVENTION

The organic carrier fuel can be produced by well-known techniques depending on the particular carrier fuel to be utilised. For example, the production of DME may be made by known techniques such as the two step process of methanol production from syngas or organic materials, followed by dehydration, or alternatively in a one stage process that completes methanol synthesis and dehydration in the same process step.

According to FIG. 1 there is a schematic presentation of fuel composition, which may be DME, pressurised into liquid form schematically showing the particulate additive dispersed through the liquid DME. Shown in FIG. 1 is a schematic exemplary fuel tank 2 having a fuel line 4. Provided in the fuel tank 2 is a fuel composition according to an exemplary embodiment comprising an organic carrier fuel 6 which may comprise a single or combination of alcohols such as bioethanol or methanol suitable for spark ignition engines. Alternatively the organic carrier fuel may comprise DME and/or MTBE. Biodiesel is another suitable organic carrier fuel. Dispersed through the organic carrier fuel 6 is a particulate additive 8 comprising a graphitic carbon material. The maximum dimension of the particulate additive is less than 20 microns and is provided within the organic carrier fuel in the range of 0.1 to 2 wt/%. A typical range may be further defined as between 0.5 to lwt/%.

In one embodiment, pyrolysis oil (which is commonly the end product of waste plastic and tyre pyrolysis) can include a particulate additive, preferably biochar, which has the beneficial effect of reducing the total acid number of the oil thereby reducing potential corrosive effect.

In use the fuel composition is drawn from the tank 2 such that the fuel drawn is in liquid form meaning that the particulate additive is uniformly drawn and fed into the engine. This ensures that there is minimal variation in the fuel composition. In the event that fuel is drawn from the head space in the form of fuel vapour, a more volatile component is selectively drawn from the head space rather than the less volatile component of the fuel composition.

Referring to FIG. 2, in step 1 an organic carrier fuel is provided in a vessel. In the event the organic carrier fuel is DME for example it is maintained pressurised and in liquid form. In step 2, the desired weight of the particulate additive is measured dependent upon the desired weight percentage for the fuel composition and in step 3 is injected accordingly. The particulate additive may be pumped or otherwise pressure injected into the vessel.

Aspects of the present invention have been described by way of example only and it will be appreciated to the skilled addressee that modifications and variations may be made without departing from the scope of protection afforded by the appended claims.

Claims

1. A fuel composition for use in an internal combustion engine comprising an organic carrier fuel having a particulate additive dispersed therein, the particulate additive comprising a lubricant.

2. The fuel composition according to claim 1 wherein the organic carrier comprises or includes alcohol.

3. The fuel composition according to claim 1 wherein the organic carrier fuel comprises or includes an ether selected from Dimethyl Ether (DME) and/or Methyl Tert-butyl Ether and/or biodiesel and/or pyrolysis oil.

4. The fuel composition according to claim 1 wherein the particulate additive comprises a graphitic carbon material.

5. The fuel composition according to claim 1 wherein the particulate additive has a high graphitic carbon content.

6. The fuel composition according to claim 4 wherein the particulate additive comprises carbon char, and wherein the carbon char may comprise biochar.

7. The fuel composition according to claim 1 wherein the particulate additive is dispersed through the organic carrier fuel, and the organic carrier fuel is stored for use in liquid form.

8. The fuel composition according to claim 1 wherein the particulate additive comprises individual particles having a maximum dimension of less than 20 microns.

9. The fuel composition according to claim 8 wherein the maximum particle size dimension is less than 1 micron, and optionally less than 0.1 micron, and optionally less than 0.01 micron.

10. The fuel composition according to claim 1 wherein the particulate additive is present in the organic carrier fuel in the range of 0.1 to 2 wt/%, and more preferably in the range of 0.5 to 1 wt/%.

11. A method of manufacturing a fuel composition for use in an internal combustion ignition engine comprising the steps of combining an organic carrier fuel with a particulate additive such that the particulate additive is dispersed in the organic carrier fuel.

12. The method according to claim 11 wherein the organic carrier fuel is provided in a vessel, and the particulate additive is injected into the vessel.

13. The method according to claim 11 wherein the organic carrier fuel is in liquid form when combining with the particulate additive.