WO2008106722A1

WO2008106722A1 - Power generation

Info

Publication number: WO2008106722A1
Application number: PCT/AU2008/000285
Authority: WO
Inventors: Timothy Standke
Original assignee: Powergen International Pty Ltd
Priority date: 2007-03-02
Filing date: 2008-03-03
Publication date: 2008-09-12

Abstract

The invention relates to an engine and a method of operating an engine (30) that employs hydrogen assisted combustion of a hydrogen gas containing fuel or fuel component. The method involves generating the hydrogen gas containing fuel at a hydrogen gas producing plant (2). The engine has a fuel introduction pre-chamber (20) into which at least a portion of the hydrogen gas containing fuel (10) or fuel component is introduced. The method further involves introducing the proportion of the hydrogen gas containing fuel into the pre-chamber which is in fluid communication with the main combustion chamber (32) of the engine (30), and operating the engine to produce power, by at least in part igniting the fuel in the pre-chamber. The introduction of the hydrogen containing fuel into the pre-chamber (20) of the fuel system of the engine (30) allows a reduced amount of hydrogen gas containing fuel to be used in an engine (30).

Description

POWER GENERATION

FIELD OF THE INVENTION

The present invention relates to producing hydrogen gas containing fuels and to use of the fuels in engines for power generation methods and processes and for transportation purposes in which the engines use hydrogen assisted combustion to produce power in which hydrogen gas is used as a fuel or one of the components of the fuel for the engine to provide power generated by the engine or to provide locomotion.

Additionally, the present invention relates to fuel introduction systems for engines operated using hydrogen assisted combustion allowing the use of hydrogen gas as the fuel or as one of the components of the fuel for the engine. In one form, the present invention relates to engines and methods of using engines having a fuel injection system that includes a pre-chamber for introducing at least a part of the hydrogen gas containing fuel, particularly synthetic gas or syngas fuel, into the engine through the pre-chamber. The advantage of using the hydrogen containing fuel and engine having the fuel injection pre-chamber is that the engine is more economical to operate and thus is able to be used to generate power, particularly in the form of electricity, more economically by using reduced amounts of fuel.

In one form, the present invention relates to syngas production and use techniques, particularly use of the syngas as a fuel for an engine, where at least a portion of a methane gas component of the syngas is separated from the remaining components of the syngas so that the two separated components can be introduced into the engine separately to provide more efficient combustion thereby generating power at a lower cost.

The present invention finds particular application in one form in power generation using a stationary engine having a fuel injection system equipped with a pre-chamber in fluid communication with a main combustion chamber or space for generating power, such as for example, in generating electricity, where part of a hydrogen containing gas such as a syngas or similar, is introduced, particularly under high pressure, into the pre-chamber of the engine where it is ignited before being introduced into the main combustion space for further combustion with the fuel already in the main combustion thereby allowing more efficient use of the fuel introduced into the engine.

Although the present invention will be described with particular reference to one form of the engine and to various sources of hydrogen gas containing fuels, such as syngas, it is to be noted that the present invention is not restricted to the described embodiment but that the present invention is more extensive so as to include other forms and arrangements of the engine, other forms and arrangements of the pre-chamber, other forms and arrangements of the fuel introduction systems, to other compositions of the fuel and to other methods of producing or manufacturing the fuel, and to applications of the engine, fuel system, fuel or methods other than generating power or providing locomotion. BACKGROUND OF THE INVENTION

With increasing concerns about the depletion of natural resources, and global warming, there is greater emphasis on using existing natural resources more wisely, including using fuels more efficiently and/or to more effectively converting natural resources into fuels. Currently, many power generating establishments use different types of fuel in various forms of engines to generate power such as for example, electricity. Some engine/fuel combinations are more efficient and effective than others. There is a continuous guest to make the engines used in power generation more fuel efficient.

In other situations, engines are used for locomotion, such as diesel engines, in trucks, buses, ships and the like. There is always a quest for greater efficiency of using fuel.

Advances in fuel efficiency occur in many ways such as for example, as a result of improvement to the engine including the structure of the engine and the methods of operating the engine, such as for example, using computer technology to achieve better combustion, as well as to improved ways of introducing fuel into the engine.

Another area of increasing fuel efficiency is improving the quality and/or type of the fuel, such as improving the calorific content of the fuel, which is combusted in the engine, or using alternative types of fuel to the more traditional fuels that are currently used. With the advent of new forms of fuel introduction systems, there is greater opportunity for using a different range of fuels more efficiently, including fuels having a different composition or derived from alternative sources. It has been surprisingly discovered that improvements in the fuel introduction systems of engines has allowed more basic types of fuels or less refined fuels or fuels derived from alternative sources of fuel, to be utilised in more technologically advanced or complex engines. In particular, it has been surprisingly discovered that hydrogen containing fuels mixed with other materials, can be used in engines having a technologically advanced fuel introduction system comprising a pre-chamber for ignition of the fuel. This is surprising as it would be expected the more technologically advanced the engine, the more pure and better quality fuels would need to be used. However, it has now been discovered that despite advances in the technology of the fuel introduction system, more basic fuels and less refined fuels can be used and moreover, the less refined fuels provide better efficiencies in the technologically advanced engines than do more advanced fuels or more refined fuels, such as gasoline, diesel or other conventional fuels.

Another problem with using alternative fuels, including older style or type fuels, is that their heat of combustion is sometimes too great to enable the fuel to be combusted efficiently and to extract all of their calorific value. Thus, there is a need for techniques of fueling engines which does not result in development of excessive heat within the engine that can cause damage to the engine .

Accordingly, it is one aim of the invention to be able to use an alternative fuel in technically advanced engines having a pre-chamber as part of the fuel introduction system.

It is another aim of the present invention to reduce the amount of alternative fuel which is used in power generation by an engine having a fuel introduction system provided with a pre-chamber.

It is another aim of the invention to be able to take advantage of advances in fuel technology to operate engines more efficiently by using older forms of fuels more efficiently, particularly different ratios of components of fuels, and/or different ratios of air to fuel.

It is another aim of the present invention to be able to use alternative fuels in engines having a pre-chamber without developing excessive heat within the pre-chamber and/or engine that could cause damage to the engine yet still extract almost all of the available calorific content of the fuel during combustion.

It is to be noted that not all aims of the invention are satisfied by all embodiments falling within the scope of the invention. Some embodiments satisfy one aim whereas other embodiments satisfy another aim. Some embodiments may satisfy two or more aims.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is provided a method of operating an engine employing hydrogen assisted combustion involving the use of a hydrogen gas containing fuel or fuel component comprising the steps of

(a) generating the hydrogen gas containing fuel for use as the fuel or one component of the fuel for the engine, said engine having a fuel introduction pre-chamber into which at least a portion of the hydrogen gas containing fuel or fuel component is introduced,

(b) introducing the proportion of the hydrogen gas containing fuel or such component into the pre-chamber of the engine, said pre-chamber being in fluid communication with the main combustion chamber of the engine, and

(c) operating the engine to produce power, by at least in part igniting the fuel in the pre-chamber,

wherein the introduction of the hydrogen containing fuel or fuel component into the pre-chamber of the fuel system of the engine allows a reduced amount of hydrogen gas containing fuel or fuel component to be used in an engine .

According to another aspect of the present invention, there is provided an engine capable of operating in a more fuel efficient manner comprising

a fuel introduction system for admitting a hydrogen gas or a hydrogen gas containing fuel or fuel component to the engine for hydrogen assisted combustion to occur within the engine

wherein the fuel introduction system includes a pre-chamber into which the hydrogen containing gas or fuel or fuel component is introduced,

said pre-chamber being in fluid communication with a main combustion chamber or space so that fuel introduced into the pre-chamber can be ignited to effect ignition and/or combustion within the main combustion chamber so that a reduced amount of fuel is used during operation of the engine.

BRIEF DESCRIPTION OF ASPECTS OF THE INVENTION

In one form, the hydrogen gas containing fuel can be generated on board the engine or vehicle or installation containing the engine or associated with the engine or can be generated remote from the engine and transported or otherwise conveyed to the engine. Preferably, the hydrogen gas containing fuel is generated either close to or associated with the engine.

In one form, the hydrogen gas containing fuel hereinafter referred to as the hydrogen fuel, can be produced in a variety of different forms or compositions and in a variety of different ways including a hydrogen fuel cell, a gasifier or other hydrogen gas or fuel gas generator.

Typically, the hydrogen generator useful in the present invention generates hydrogen in combination with other materials. Typically, the hydrogen generator is an electrolysis apparatus, a fuel cell, a fuel processor, a reformer, a cold fusion apparatus, a gasifier or the like, and includes any apparatus for making hydrogen either alone or in combination with other gases, such as for example, a coal gasifier for producing gases. Typically the fuel cell is a proton exchange fuel cell (PEMFC) , solid oxide fuel cell (SOFC) , an alkaline fuel cell (AFC) , direct methanol fuel cell (DMFC) , a molten carbonated fuel cell (MCFC) , phosphoric acid fuel cell (PAFC), or a regenerative fuel cell (RFC), or the like. Operation of the fuel cells is reversed from their normal method of operation so as to be used to generate hydrogen gas rather than using hydrogen to produce energy.

More typically, the hydrogen generator is a reformer in which steam is used to heat a fuel as it passes over a catalyst. Typically, the fuel and steam are chemically cracked. The reformers generally reform a hydrocarbon fuel to hydrogen gas with the aid of steam. Typically, the hydrogen produced in the hydrogen generator, typically the fuel cell, is produced in combination with oxygen, nitrogen, water, ethanol, carbon dioxide, carbon monoxide, hydrocarbons, methanol, methane or the like.

Typical sources of hydrogen or the hydrogen containing gas or fuel component include coal, manure, ethanol, solid municipal waste, diesel, tyres, sewerage or the like. Other sources of hydrogen include hydrocarbons or materials containing hydrocarbons that can burn or be broken down to form hydrogen.

If necessary, or required, the feedstock can be reprocessed to be comminuted to smaller pieces, and/or be placed in a cartridge to be gasified, or liquefied by heat and/or injected by nozzle. Typically, the hydrocarbon material introduced into and/or produced in the hydrogen generator includes a paraffin or paraffin-like hydrocarbon containing saturated bonds. More typically, the hydrocarbon is selected from Ci-C₂₀, preferably from C₂-Ci₂, more preferably C₄-Ci₀, and most preferably C₈ hydrocarbons, including mixtures and combinations of at least one or more such materials.

Typically, the methanol, methane or similar materials are a byproduct from the fuel used in the hydrogen generator, such as the reformer to produce the hydrogen, such as for example, being derived from the original reformer-based fuel, such as diesel, petrol, canola oil or the like. The methanol is introduced into the fuel injection system of the engine along with the hydrogen gas fuel or fuel component .

Typically, the gaseous blend or mixture produced by the hydrogen generator contains from about 1-50% by volume of hydrogen, preferably from about 30-40% by volume, and more preferably 35-38% by volume hydrogen. Typically, there is from 0-25% by volume of carbon monoxide, preferably 3-5% by volume, and more preferably 4-5% by volume carbon monoxide produced in the hydrogen generator. Even more typically, the amount of hydrocarbon material is from 0-5% by volume, typically 1-4% by volume, and preferably 2-3% by volume. Typically, the amount of carbon dioxide produced is from 0-25% by volume, preferably 5-15% by volume, and more preferably 3-10% by volume. It is to be noted that the balance of any gaseous blend or mixture produced by the hydrogen generator is nitrogen, methanol, water vapour, methane or other gases as required or desired depending upon circumstances, including the need to eliminate, prevent, reduce, minimise or the like pre- ignition, or the like and/or to operate the engine more efficiently.

Another aspect of the present invention is the ability to preselect, predetermine or the like the ratio of individual components in the gaseous blend or mixture being produced by the hydrogen generator. Depending upon the requirements of the engine, the hydrogen generator can be operated at selectively adjustable parameters in order to provide the optimal amounts of each of the components and the ratio of the various components of the gaseous blend or mixture to achieve maximum efficiencies of the operation of the engine, depending upon a number of factors of the engine such as for example, whether in the interest of economy, the same amount of power with reduced fuel consumption or in the interest of power, producing more power for the same fuel consumption, depending upon the load requirements placed upon the generator producing power, electricity or the like.

Typical parameters of the materials being fed to the engine are the gas flows or gas velocities of the various components and the overall composition of the mixture of components, the temperature at which the hydrogen generator is operated, the pressure at which the hydrogen generator is operated, the velocity of gas being passed through, produced by or formed in the generator, the catalyst being used in the generator, the amount of exposure of the reactants to the catalyst, the type of hydrogen generator being used or the like. - li lt is to be noted that the operating conditions of the hydrogen generator are adjustable so that the production of certain components can be minimised or prevented by- operating the system within set parameters or amounts . However, it is to be noted also that the production of other components can be optimised.

Typical operating conditions of the reformer which catalytically decomposes or cracks heated steam to produce hydrogen and oxygen include the following. The reformer can be operated at a temperature of from 100⁰C-1, 000⁰C, typically from 200°C-900°C, preferably from 220°C-800°C.

Typically, the pressure of operation of the reformer is from 1-5 bar, typically from 1-3 bar and preferably at about 2 bar absolute.

Typically, the reformer can produce any volume or amount of gas depending upon the size of the gas generator and the application in which the hydrogen assisted composition is used. Typical catalysts include platinum, nickel or any other suitable catalyst for catalysing the reforming of hydrogen from heated steam.

In one form, the hydrogen containing gas includes hydrogen gas either alone or in combination with other materials. The other materials include carbon monoxide, carbon dioxide, water vapour, nitrogen, methane and combinations of two or more gasses. A preferred gas is a synthetic gas, or syngas.

A particularly preferred form of the hydrogen gas containing fuel is syngas essentially which contains hydrogen, carbon monoxide, carbon dioxide and methane.

In one form, the syngas is produced by the gasifier or hydrogen generator as a combined gas containing all of the components as a mixture. Preferably, the methane is separated from the remaining gaseous components . More preferably, only a proportion of the methane is separated from the remaining cases. Preferably, up to about 10% by mass or heat content or calorific content, such as BTUs, of the methane is separated, more preferably from about 0.1% to about 5%, most preferably from about 1% to about 2% is separated from the remaining fuel component.

In another form, the syngas is produced by the gasifier or hydrogen separator as separate streams in which methane is contained in one stream and the remaining components of the syngas fuel product is in another stream. Preferably, the two streams are combined. More preferably, part of the methane stream is combined with the other stream.

More preferably, part of the methane stream is combined with the other stream. Preferably, the methane stream contains up to about 10% of the total methane, more preferably from about 0.1% to about 5%, most preferably from about 1% to about 2% of the total methane or total energy of this stream or of the total energy of the syngas .

Typically, the production of syngas, from suitable feedstock or raw material uses the Fisher-Tropsch Process, particularly to produce diesel fuel, and involves the use of scrubber technology to separate the methane stream from the remaining gases of the syngas composition, either before the gas stream exits the gasifier or after the gas stream exits the gasifier.

In one form, the engine is a combustion engine including internal combustion engines such as spark ignition engines and compression ignition engines.

Typically, the charge of fuel in the pre-chamber ignites due to compression ignition or ignites due to spark energy from a suitable spark producing device, such as for example, a spark plug. More typically, the main charge within the cylinder is ignited by the ignition flare originating from the pre-chamber which is discharged from the pre-chamber into the main chamber.

Thus, the present invention includes a spark plug type ignition pre-chamber module as well as the MAN compression ignition pre-chamber.

In one form, the fuel system of the engine is a fuel injection system. Preferably, the fuel injection system includes an insert. More preferably, the insert contains the pre-chamber. Even more preferably, the pre-chamber is in fluid communication with the main combustion chamber or space. Even more preferably, ignition of the fuel in the pre-chamber also causes, at least in part, ignition of the fuel in the main combustion chamber or space by propagation of the spark, ignition or combustion into the main chamber.

One particularly preferred form of engine useful in the present invention is a self igniting, mixture-compressing internal combustion engine, using an hydrogen assisted combustion which engine includes a cylinder having a cylinder head, an insert operably engaged with the cylinder head, a main combustion space in the cylinder and a pre-chamber located in the insert in which the pre- chamber and main chamber are in fluid communication with each other.

The fuel injection system of the engine can be a low pressure system or a high pressure system or a combination of low and high pressures depending upon the actual construction of the fuel injection system.

In one particularly preferred arrangement, there is a low pressure fuel line connected to the main combustion space or chamber of the engine and the fuel line connected to the pre-chamber located within the insert is a high pressure fuel line. Preferably, methane is injected under high pressure into the pre-chamber. Preferably, the remaining fuel components are injected under low pressure into the main combustion space. Preferably, the low pressure is from about 0 psi up to about 100 psi, more preferably from about 0 psi to about 15 psi or alternatively from about 20 psi to about 100 psi.

Optionally, there is a mixer unit or similar located in the low pressure line connected for introduction of fuel into the main combustion space or chamber. Optionally, the mixer has a number of separate inlets for admitting different components of the fuel.

Typically, the cylinder pressures can be as high as 4000 psi during combustion. Typically, diesel fuel injectors are about 17,000 psi and reach pressures of 21,000 psi. Typically, fuel is introduced into the engine, other than in the pre-chamber, in the air intake system somewhere. Preferably at the intake port. This is "low pressure" fuelling. As low pressure fuelling is a relative term, this is relative to the high pressure mentioned above. However, there are a number of different mechanisms that can introduce fuel into the intake port, including the following:

• A venturi might be used at the throttle which means that the low fuel pressure will be less than atmospheric (negative pressure system , 0>p>15 psia) .

• A *spud' tube might be used where the inlet fuel pressure is atmospheric (roughly ~15 psia) .

• An injector might be used where sonic flow across the nozzle is required to meter the fuel flow. This pressure would be 20<P<100 psia.

There may even be other mechanisms for fuelling at low pressure. Also, there is the effect of turbo charging which raises all but the maximum number by whatever boost pressure is (typically 1.5 to 2 bar). More typically, the pressures of interest for "low pressure" fuelling is from about 0 to about 100 psi absolute.

In one embodiment, the hydrogen can be stored after production or generation in gaseous, liquid or some other form. Typically, gaseous or liquid hydrogen is stored under pressure. More typically, the pressurised storage systems are located remote from the engine. The hydrogen may be stored in other forms, such as hydrides, e.g. magnesium hydrides, compounds of magnesium nickel, magnesium copper, irontitanium or the like which absorb hydrogen and release hydrogen when heated.

Typically, the hydrogen generator includes the use of pelletised metals, e.g. sodium encapsulated with polyethylene to produce hydrogen when opened.

Another form of producing the hydrogen containing gas for use as a fuel is through coal gasification. In this case, syngas is produced containing a mixture of hydrogen, carbon monoxide, carbon dioxide, and methane, optionally including other gases. Coal gasification to hydrogen and other gases offers a versatile and clean method of converting coal into electricity and hydrogen gas containing fuels. In one example, coal gasification involves exposing coal to steam in the presence of controlled amounts of air or oxygen under high temperatures and pressures to form a gaseous mixture containing hydrogen, such as for example, a mixture of hydrogen, carbon monoxide, methane and other gaseous compounds such as carbon dioxide, water vapour, or the like. One product of gasification is syngas.

In one form, the size of the pre-chamber is up to about 1%, preferably from about 0.2% to about 0.3% of the size of the main combustion chamber of the engine. However, other ratios of sizes of pre-chamber to main chamber are possible.

In one form, the fuel introduction system is a fuel injection system, either a high pressure fuel injection system or a low pressure fuel injection system. A preferred form of the injection system is a combination of high and low pressures.

In one form, the engine is a stratified charge engine having a gradient of fuel charge or different fuel charges in different regions of the combustion charge of the engine. The pre-chamber has a rich fuel charge whereas the main combustion chamber has a lean fuel charge. Some regions within the combustion chamber have little or no fuel in the charge but contain gases such as nitrogen, oxygen or the like including combinations.

BRIEF DESCRIPTION OF THE DRAWINGS

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

Figure l(a) is a schematic view of one form of the method of generating power according to the present invention using syngas produced in a gasification plant,

Figure 1 (b) is a schematic view of another form of the method of generating power according to the present invention using a hydrogen generator to produce a supply of gaseous hydrogen,

Figure 2 (a) is a schematic view of one form of the fuel introduction system useful in the present invention having a single syngas stream produced by the gasifier,

Figure 2 (b) is a schematic view of another form of the fuel introduction system useful in the present invention showing two separate streams produced by the gasifier.

DETAILED DESCRIPTION OF THE INVENTION

EXAMPLE 1

One embodiment of the present invention will now be described.

In this embodiment, shown schematically in Figure 1 (a) , the required raw materials such as for example, coal, particularly using clean coal gas feedstocks, are admitted to a suitable gasification plant 2, in which syngas is manufactured. In one form, the gasification plant 2 may be associated with an engine 30 or syngas may be produced in a location close to the engine 30 whereas, in another embodiment, the syngas may be transported from a remote location to the power generation site for use in the engine. Syngas produced by the gasification plant 2 is the fuel, or forms one component of the fuel of the engine 30 along with air and optionally other fuels such as more traditional hydrocarbon fuels, such as diesel, or other additives such as water, methanol or the like. The various components of the fuel are introduced either in combination with one another in a single fuel stream, or separately into the engine such as for example, using a fuel injection system in which one component, such as the syngas is introduced in one stream 10, and the other components are introduced in another stream 12. One example of the fuel injection system and engine (incorporated in Figure Ka)), is disclosed in United States Patent 6,843,220 which discloses the engine 30 having a fuel injection system with a pre-chamber 20 located in an insert 22 attached to the cylinder head (not shown) of engine 30. One of the fuel components or part of the fuel, in this example, part of a stream 10 of syngas, is introduced under high pressure to the pre- chamber 20 where it is ignited. Ignited fuel flows into a main combustion chamber 32, for example a cylinder in the engine 30, to ignite the fuel 12 located therein which has been injected using low pressure. Alternatively, the spark ignition within the pre-chamber 20 is propagated into the main combustion chamber 32 where the remainder of the charged fuel 12 is combusted.

In one embodiment as shown in the drawings, the engine 30 having the pre-chamber insert 22 in fluid communication with the main combustion chamber 32 is coupled to an electricity generator 40 for generating electricity. The electricity is then fed to the power grid or to an installation such as for example, a building, chemical plant or the like.

In another embodiment, (not shown) , the engine 30 is used for locomotion and transport, such as for example in a bus, truck, ship or other marine application.

EXAMPLE 2

Another embodiment of the invention will now be described.

In a modified form of the present invention, hydrogen is produced in a suitable hydrogen generator 4, such as for example, a fuel cell operating in reverse or a reformer producing a reformate gas containing hydrogen produced from a hydrocarbon source. The hydrogen generator 4 can be located on or near to the engine 30 or be associated with the engine or the hydrogen source may be located remote from the engine 30 and hydrogen transported to the engine 30 such as for example, by vehicular transport, pipeline or similar. It is preferred that the hydrogen be produced on board or at or on the engine 30.

Hydrogen, along with other components of the fuel is introduced through the fuel injection system of the engine 30. Again, one preferred form of the fuel injection system of the engine (incorporated into Figure Kb)), is disclosed in US 6,843,220. In one form, part of the fuel, particularly the hydrogen or hydrogen containing gas 12, is admitted to the pre-chamber 30 of the engine 30 whereas the remainder of the fuel 12, including the hydrogen 14 is introduced into the main combustion chamber 32.

The engine 30 is used to drive a generator for producing electricity. Alternatively, the engine is used in a vehicle for transportation, such as for example, in a marine application.

EXAMPLE 3

In another form, the present invention includes the production of syngas in a combined stream having all of the components of the syngas. In this embodiment, shown in Figure 2 (a) , suitable raw materials including coal and other coal related feedstock, is introduced into a hydrogen gas generator in the form of a gasifier 6, in which syngas is produced. The gasifier 6 can be a conventional gasifier using existing technology for producing syngas from coal, such as for example, using the Fisher-Tropsch Process. A single stream of syngas 10 is discharged from the gasifier 6 for introduction into a syngas separator 50 for separating methane 16 from the remaining components of the syngas . The separated methane gas stream 16 is discharged from the syngas separator 50 separately to the other components 18 of the syngas 10, for injection under high pressure into the pre-chamber 20 of the engine 30. The pre-chamber 20 arrangement of the engine 30 is the same as or similar to the insert containing the pre-chamber 20 as disclosed in US 6,843,220. Typically, up to about 10% of the amount of methane produced in the syngas separator is introduced into the pre-chamber 20 for combustion. However, it is preferred that from about 1% to about 2% of the methane be introduced into the pre-chamber 20 with the remainder of methane being combined with other fuel components including the other components 18 of the syngas for introduction into the main combustion chamber 32. The advantage of using methane only as the fuel being introduced into the pre-chamber, is that as methane is a natural gas, little or no modification of the insert (shown in Figure 2 (a) ) , forming the pre-chamber 20 is required. If syngas is used as the fuel component introduced into the pre-chamber 20, there is a chance that excessive heat may be produced resulting in damage to the engine 30.

The separated stream containing the other components 18 of the syngas apart from methane, are discharged from the syngas separator 50 and are admitted under low pressure to the main combustion chamber 32, or space of the engine 30. The other fuel components may be directly injected under low pressure into the main combustion chamber 32 or may be introduced into a mixer 60 first for mixing with other fuel components before being injected under low pressure into the main combustion chamber 32.

The mixer may be any suitable type, such as for example, a suitable mixer is a mixer of the type disclosed in US 10/432,694.

Optionally, the mixer 60 has a number of injection ports for introducing various components of the overall fuel for mixing prior to being introduced into the main combustion chamber 32 of the engine 30. Water in the form of atomised water is introduced through the mixer 60.

It is to be noted that syngas cannot be used as the only supply of fuel in an engine as the combustion of the syngas produces excessive heat which causes damage and overheating to the engine. However, as methane 16 is removed from the syngas and methane is more akin to a natural gas, the introduction and ignition of methane 16 in the pre-chamber 20 has a cooling effect in the pre- chamber 20 as the combustion of methane 16 in the pre- chamber 20 does not generate excessively high temperatures.

EXAMPLE 4

In the embodiment illustrated in Figure 2 (b) , the raw materials or feedstock, such as for example, coal, are introduced into a hydrogen gas generator in the form of a gasifier 8 in which syngas is produced. This form of the gasifier 8 is also provided with an internal separator for separating the syngas internally within the gasifier into two streams with one stream containing methane 16 and the other stream containing the other gaseous components 18 of the syngas apart from methane. The methane gas stream 16 is injected under high pressure into the pre-chamber 20 of the engine 30 where ignition takes place producing a flare. It is to be noted that not all of the methane need be separated in the gasifier 8 since only a small proportion of the methane 16 is introduced into the pre- chamber 20 of the engine 30, only some of the methane 16 needs to discharged separately from the other components 18 of the syngas.

The other gaseous components 18 of the syngas production in the gasifier 8 are injected under low pressure into the main combustion space 32 or chamber of the engine 30. The injection may be direct injection or via an intermediate component or accessory, such as for example an optional mixer. A mixer unit 60 is optionally located in the low pressure line from the gasifier 8 to the engine 30. The mixer unit 60 allows methane not used in the high pressure line injected into the pre-chamber 20 to be recombined with the remaining fuel components for low pressure injection into the engine. In one form, the mixer 60 is in accordance with US 10/432,694.

The separation of the methane 16 as a natural gas from the syngas allows part of the methane 16 to be injected directly into the pre-chamber 20. Rather than injecting a syngas mixture which results in excessively hot combustion, the separation of the methane 60 from the remaining components 18 allows a natural gas of methane to be introduced into the pre-chamber 20 to initiate combustion by producing a flare in the pre-chamber 20. This does not result in the production of excessive heat within either the pre-chamber 20 or main combustion chamber 32.

The flare produced in the pre-chamber 20 flows into the main combustion chamber 32 thereby causing ignition of the fuel charge located in the main combustion chamber 32.

The various forms of the present invention as described in this specification can be used in static engines for the generation of power, electricity or the like or can be used in mobile engines for mobility in locomotion such as for example, in trucks, buses, ships and other uses where heavy duty engines are required.

Modifications of the present invention include the following:

Atomised water may be introduced into the optional mixer to combine with the syngas fuel or other fuel components or fuel additives.

In one form, the mixer unit 60 is a hydrojector mixer unit having separate inlets for air or oxygen, water vapour, fuel or the like for mixing the various components of the fuel into the overall fuel for the engine.

Another modification includes having a fixed venturi, butterfly throttle, butterfly venturi or the like controlling the mixing of the various fuel components.

In one form, the engine is provided with an inlet port, port feed injection or the like.

In one embodiment, the fuel charge in the main combustion chamber 32 is a lean charge of fuel whereas as the fuel charge in the pre-chamber 20 is a rich charge of fuel so that there is a graduation of fuel charge from rich to vary lean within the combustion chamber, similar to a stratified charge which results in less fuel being consumed.

The main combustion chamber 32 of the engine 30 in accordance with the present invention has a lambda value of from about 1 to about 3 or even more. However, it is to be noted that the leaner the value, the better (lambda value >1) . More typically, the lambda value greater than 2 is expected. The values are high enough to allow the combustion to be cool enough to prevent NO_x formation but not so lean a fuel charge that the engine misfires. It is desirable to go as lean as possible without misfiring occurring. In one form, the pre-chamber has a lambda value of 1 ± 30% to encourage strong combustion. However, it is desirable to have a lean charge even with the pre-chamber as high as 1.4 lambda to discourage NO_x formation.

ADVANTAGES AND APPLICATION OF THE INVENTION

Advantages of the present invention include:

• Coal gasification is already being done, so turbine engines can be replaced,

• Gasification in general allows the use of feedstock from bio, renewable and waste products. Therefore, power generation can be achieved from the same plant, but from many sources.

• Assists in solving municipal waste situations.

• Piston engines are much easier to maintain than turbine engines (operating costs are lower) . • Piston Engines are typically cheaper to purchase at the same kW ranges .

• Even natural gas can be gasified to H2 and reduce C02 emissions.

• Many island countries rely on import of diesel to power their cities, with this technique, local waste and bio resources can be used to generate power for independence .

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

It will be understood to persons skilled in the art of the invention that many modifications may be made without departing from the spirit and scope of the invention.

Claims

CLAIMS :

1. A method of operating an engine employing hydrogen assisted combustion involving the use of a hydrogen gas containing fuel or fuel component comprising the steps of:

wherein the introduction of the hydrogen containing fuel or fuel component into the pre-chamber of the fuel system of the engine allows a reduced amount of hydrogen gas containing fuel or fuel component to be used in an engine.

2. The method defined in claim 1, wherein step (a) involves generating hydrogen or the hydrogen containing gas or fuel component from coal, manure, ethanol, solid municipal waste, diesel, tyres, sewerage or the like.

3. The method defined in claim 1 or claim 2, wherein the step (a) involves reprocessing of feedstock for generating the hydrogen gas containing fuel for use as the fuel or one component of the fuel for the engine by comminution into to smaller pieces, and/or by placement in a cartridge to be gasified, or by liquification by heat and/or by injection by a nozzle.

4. The method defined in any one of the preceding claims, wherein step (a) involves generating hydrogen or the hydrogen containing gas or fuel component from hydrocarbons or materials containing hydrocarbons that are combustible or break down to form hydrogen.

5. The method defined in claim 4, wherein the hydrocarbon material used to generate hydrogen or the hydrogen containing gas or fuel component is a paraffin or a paraffin-like hydrocarbon containing saturated bonds.

6. The method defined in claim 5, wherein the hydrocarbon is selected from C1-C2₀/ preferably from C2-C₁₂, more preferably C4-C10, and most preferably C₈ hydrocarbons, including mixtures and combinations of at least one or more such materials.

7. The method defined in any one of the preceding claims, wherein hydrogen containing gas fuel is charged to the pre-chamber and step (c) involves igniting the charge by spark or compression ignition.

8. The method defined in claim 7 , wherein the hydrogen containing gas fuel is charged to the pre-chamber under high pressure.

9. The method defined in any one of the preceding claims, wherein step (c) involves charging other fuel components into a main combustion chamber under low pressure.

10. The method defined in claim 9, wherein the low pressure is from about 0 psi up to about 100 psi, more preferably from about 0 psi to about 15 psi or alternatively from about 20 psi to about 100 psi.

11. The method defined in claim 9 or claim 10, , wherein the other fuel components comprise byproducts from the fuel used to generate hydrogen in step (a) and are charged into the main combustion chamber for ignition by the hydrogen gas containing fuel or such component that is ignited in the pre-chamber.

12. The method defined in any one of claims 9 to 11, wherein step (c) involves igniting fuel charged to the main combustion chamber by spark ignition or by an ignition flare originating from the pre-chamber which is discharged from the pre-chamber into the main chamber.

13. The method defined in claim 11, wherein the byproduct is methanol, methane or similar materials being derived from the original reformer-based fuel, such as diesel, petrol, canola oil or the like.

14. The method defined in claim 9 or claim 10, wherein a first stream of the hydrogen containing gas fuel is charged to the pre-chamber and a second stream of the hydrogen containing gas fuel is mixed with byproducts from the fuel used to generate hydrogen in step (a) and is introduced into the main combustion chamber.

15. The method defined in any one of the preceding claims, wherein step (a) generates hydrogen gas containing fuel comprising a gaseous blend which contains hydrogen, carbon monoxide, carbon dioxide and methane.

16. The method defined in claim 15, wherein the gaseous blend contains: • from about 1-50% by volume of hydrogen, preferably from about 30-40% by volume, and more preferably 35- 38% by volume hydrogen; • from 0-25% by volume of carbon monoxide, preferably 3-5% by volume, and more preferably 4-5% by volume carbon monoxide produced in the hydrogen generator;

• the amount of hydrocarbon material is from 0-5% by volume, typically 1-4% by volume of hydrocarbon material, and preferably 2-3% by volume;

• from 0-25% by volume carbon dioxide, preferably 5-15% by volume, and more preferably 3-10% by volume; and

• the balance of the gaseous blend produced by step (a) comprises nitrogen, methanol, water vapor, methane or other gases.

17. The method defined in any one of the preceding claims, wherein step (a) involves generating the hydrogen gas containing fuel with a gasifier and the methane in the gaseous mixture produced in step (a) is separated from the gaseous mixture.

18. The method defined in claim 17, wherein a proportion of the methane is separated.

19. The method defined in claim 18, wherein the proportion of methane that is separate from the gaseous mixture comprises up to about 10% by mass or heat content or calorific content, such as BTUs, more preferably from about 0.1% to about 5%, and most preferably from about 1% to about 2% is separated.

20. The method defined in claim 17, wherein the gaseous mixture generated in step (a) by the gasifier is generated as separate streams in which methane is contained in a first stream of the gaseous mixture and the remaining components of the gaseous mixture are in a second stream.

21. The method defined in claim 20, wherein the two streams are combined.

22. The method defined in claim 20, wherein part of the first stream is combined with the second stream.

23. The method defined in any one of the preceding claims 20 to 22, wherein the first stream contains up to about 10% of the total methane, more preferably from about 0.1% to about 5%, most preferably from about 1% to about 2% of the total methane or total energy of the first stream or of the total energy of gaseous mixture.

24. The method defined in any one of the preceding claims, wherein step (a) involves generating the hydrogen gas containing fuel from suitable feedstock or raw material using the Fisher-Tropsch Process, particularly to produce diesel fuel, and involves scrubbing to generated hydrogen gas containing fuel to separate the methane stream from the remaining gases of gaseous mixture, either before the gas stream exits the gasifier or after the gas stream exits the gasifier.

25. The method defined in claim 15 or claim 16, wherein the gaseous blend comprises a predetermined ratio of gases to optimise operation of the engine.

26. The method defined in claim 25, wherein the predetermined ratio is obtained by selectively adjusting of operation of step (a) to produce the gaseous blend with gases in a predetermined ratio.

27. The method defined in any one of claims 1 to 16, wherein step (a) involves generating hydrogen containing gas with a reformer.

28. The method defined in claim 27, wherein the reformer operates at a temperature of from 100⁰C-1, 000⁰C, typically from 200°C-900°C, and preferably from 220°C-800°C.

29. The method defined in claim 27 or claim 28, wherein the reformer operates at a pressure of from 1-5 bar, typically from 1-3 bar and preferably at about 2 bar absolute.

30. The method defined in any one of claims 27 to 29, wherein the reformer includes catalysts comprising platinum, nickel or any other suitable catalyst for catalysing the reforming of hydrogen from heated steam.

31. The method defined in any one of the preceding claims, wherein the hydrogen containing gas fuel is stored as gas or liquid prior to charging to the pre-chamber.

32. The method defined in claim 31, wherein the gas or liquid is stored remotely from a vehicle on which the engine is mounted.

33. The method defined in any one of claims 1 to 30, wherein the hydrogen is stored as hydrides, e.g. magnesium hydrides being compounds of magnesium/nickel, magnesium/ copper or iron/titanium or the like which absorb hydrogen and release hydrogen when heated.

34. The method defined in claim 33, wherein the hydrogen containing gas fuel is stored in pelletised metals, e.g. sodium encapsulated with polyethylene to produce hydrogen when opened.

35. The method defined in any one of the preceding claims, wherein step (a) involves generating the hydrogen containing gas fuel by coal gasification.

36. An engine capable of operating in a more fuel efficient manner comprising a fuel introduction system for admitting a hydrogen gas or a hydrogen gas containing fuel or fuel component to the engine for hydrogen assisted combustion to occur within the engine

37. The engine defined in claim 36 comprising a hydrogen generator.

38. The engine defined in claim 37, wherein the hydrogen generator comprises any apparatus for making hydrogen either alone or in combination with other gases, such as for example, a coal gasifier for producing gases.

39. The engine defined in claim 37, wherein the hydrogen generator is an electrolysis apparatus, a fuel cell, a fuel processor, a reformer, a cold fusion apparatus, a gasifier or the like.

40. The engine defined in any one of claims 36 to 39, wherein the hydrogen produced in the hydrogen generator, is produced in combination with oxygen, nitrogen, water, ethanol, carbon dioxide, carbon monoxide, hydrocarbons, methanol, methane or the like.

41. The engine defined in claim 39, wherein the fuel cell is a proton exchange fuel cell (PEMFC) , solid oxide fuel cell (SOFC) , an alkaline fuel cell (AFC) , direct methanol fuel cell (DMFC) , a molten carbonated fuel cell (MCFC) , phosphoric acid fuel cell (PAFC) , or a regenerative fuel cell (RFC) , or the like.

42. The engine defined in claim 41, wherein operation of the fuel cells is reversed from their normal method of operation so as to be used to generate hydrogen gas rather than using hydrogen to produce energy.

43. The engine defined in claim 39, wherein the hydrogen generator is a reformer in which steam is used to heat a fuel as it passes over a catalyst.

44. The engine defined in claim 43, wherein the fuel and steam are chemically cracked.

45. The engine defined in any one of claims 36 to 44, wherein the engine is a combustion engine with either spark or compression ignition.

46. The engine defined in claim 45, wherein the engine includes a spark producing device.

47. The engine defined in claim 46, wherein the engine includes a spark plug type ignition pre-chamber module as well as the MAN compression ignition pre- chamber.

48. The engine defined in claim 36, wherein the fuel introduction system is a fuel injection system.

49. The engine defined in claim 48, wherein the fuel injection system includes an insert that contains the pre- chamber such that the pre-chamber is in fluid communication with the main combustion chamber, whereby ignition of the fuel in the pre-chamber also causes, at least in part, ignition of the fuel in the main combustion chamber by propagation of the spark ignition or by propagation of an ignition flare into the main chamber.

50. The engine defined in claim 36, wherein the engine comprises a self igniting, mixture-compressing internal combustion engine, using hydrogen assisted combustion and which engine includes a cylinder having a cylinder head, an insert operably engaged with the cylinder head, a main combustion space in the cylinder and a pre-chamber located in the insert and the pre-chamber and main chamber are in fluid communication with each other.

51. The engine defined in any one of claims 36 to 50, wherein the engine includes a low pressure fuel line connected to the main combustion space or chamber of the engine and a high pressure fuel line connected to the pre- chamber located within the insert.

52. The engine defined in any one of claims 36 to 51, wherein the engine comprises a mixer located in the low pressure line connected for introduction of fuel into the main combustion space.

53. The engine defined in claim 52, wherein the mixer has a number of separate inlets for admitting different components of the fuel.

54. The engine defined in any one of claims 36 to 53, wherein fuel is injected in the main combustion chamber from the low pressure line via a port,

55. The engine defined in claim 54, wherein the port is an air intake port for admitting air into the main combustion chamber.

56. The engine defined in claim 55, wherein the port comprises any one port selected from the following group: a venturi, a 'spud' tube or an injector

57. The engine defined in any one of claims 36 to 56, wherein the size of the pre-chamber is up to about 1%, preferably from about 0.2% to about 0.3% of the size of the main combustion chamber of the engine.

58. The engine defined in any one of claims 36 to 57, wherein the engine is a stratified charge engine having a gradient of fuel charge or different fuel charges in different regions of the combustion charge of the engine.

59. The engine defined in any one of claims 36 to 58, wherein the pre-chamber has a rich fuel charge and the main combustion chamber has a lean fuel charge.