TECHNICAL FIELD

This invention relates to a method of, and apparatus for, treating a hydrocarbon including a fractionating process. In particular it is concerned with a process for obtaining from a base hydrocarbon feedstock material either an improved product for subsequent process steps or to break down the feedstock material into two or more fractionating product fractions.

A typical fractionating process for this purpose is distillation when a liquid made up of a mixture of two or more hydrocarbon components is heated to its boiling point. As a result a vapour or mixture of vapours is released from the boiling mixture. A distillation process relies on a difference in composition between liquid and vapour phases when the liquid and the vapour are in equilibrium.

BACKGROUND ART

Crude oil depending upon what fields it is recovered can vary in its constituents quite apart from the proportions of the hydrocarbons involved. If, as is usually the case, the crude oil is to serve as a feedstock for subsequent processes there are advantages to be gained from a preliminary processing of the crude oil to remove or reduce constituents, such as sulphur for example, whose presence in one form or another can be prejudicial to subsequent processing stages. The matter of preliminary precessing will be returned to later but any preliminary process should not involve the application of extreme temperatures or pressures or the use of catalysts or of large amounts of electrical power.

Where the feedstock is to be subject to fractionation or distillation different types are available in a wide range of industries such as fuel refining and food generation. Typically in oil refining a feed stock in the form of a hydrocarbon mixture made up of range of components of varying volatility are distilled to provide a range of product fractions extending from at one end a dense base material of very low volatility through a range of liquids of progressively reducing density to, at the other end, a highly volatile vapour.

One form of distillation of a feed stock is known as rectification and provides for a sequence of vapours to be obtained from a feed stock in a still. From the heated feed stock in the a vapour is obtained that is richer in volatile components than the liquid remaining in the still. The vapour is subsequently condensed. Rectification can be undertaken is one or more fractionating columns to provide for successive vaporisation and condensation stages to be accomplished to provide a range of products. Typically crude oil can be broken down into a range of products varying from a viscous tar to a high octane petrol.

By way of example Figure 1 shows a conventional three stage fractionating process with three vessels 11, 12, 13 arranged in series. Liquid Ll in vessel 11 is boiled by way of steam coil 14 to give vapour VI which passes to vessel 12 by pipe 15 and being at a higher temperature than the boiling point of liquid L2 causes vapour VI to condense and yield up heat to boil liquid L2 to give vapour V2. Vapour V2 passes to vessel 13 by way of pipe 16 to cause vapour V2 to condense and yield up heat to boil liquid L3 to give vapour V3. This passes through pipe 17 to a condenser 18 which serves to condense some of the denser fractions and return them to vessel 13 by way of pipe 19. The uncondensed fraction from condenser 18 passes on by way of pipe 10 to a further processing stage.

At each stage as the generated vapour is richer in vapour component than the liquid from which it is evolved the vapour component in the liquid will fall. In order to maintain an acceptable vapour component in the liquid at a given stage a return flow is established from the next stage. Thus pipe 19 serves to restore a proportion of condensed vapour to liquid L3 in vessel 13. Pipe 20 serves to return condensed liquid L3 from vessel 13 to vessel 12. Pipe 21 serves to return liquid L2 in vessel 12 to liquid Ll in vessel 11. The system also makes use of conventional control systems and components to provide for regulation of throughput and the proportions of the various required fractions.

Such a refining process is used for fuel oil which having been recovered in a crude state is subsequently treated by means of the refining process to provide a number of fractions of fuel oil varying in density from a fuel with an octane number in excess of 95 down through a range of fuels including petrol with octane numbers of 85 or over

and diesel oil. The residue is a tar like material remaining in the base of the first distillation vessel. The process outlined in Figure 1 can be extended by adding further vessels to the three described to produce further fractionation. The refining process used for this purpose involves a sequence of distillation vessels. The first in the sequence involves the heating of crude feed stock to provide for vaporisation of volatile fractions in the first vessel. Thereafter latent heat is used to provide heating for liquid in the next vessel in the sequence. In more elaborate systems it becomes necessary to improve fractionation by means of catalytic 'cracking' processes involving the use of hydrogen to enhance hydrocarbon products. Such processes are necessarily elaborate, introduce safety problems and require operation at high pressures and temperatures. Such installations are necessarily costly.

DISCLOSURE OF INVENTION

According to a first aspect of the present invention there is provided a method of treating a hydrocarbon feedstock material including water characterised by the steps of:

1 supplying the feedstock material as a working medium along a flow path through a vessel;

2 directing an oxidising gas flow into the vessel so as to provide for the oxidising gas to pass through the working medium with intimate mixing between the gas and the working medium;

3 enabling at least one product generated by chemical or physical interaction between the gas and the working material to be withdrawn from the flowpath by way of an extraction path.

According to a first preferred version of the first aspect of the present invention method of fractionating a hydrocarbon feedstock material is characterised in that the steps of: 1 supplying the feedstock material as a working medium along a flow path through a vessel; involves providing in the vessel the working medium as a column of working material;

2 directing an oxidising gas flow into the vessel so as to provide for the oxidising gas to pass through the working medium involves directing an oxidising gas from a first location in the vessel so as to pass through the column of working material with intimate mixing;

3 enabling at least one product generated by chemical or physical interaction between the gas and the working material involves the product being generated as a fractionation product generated by chemical or physical interaction between the gas and the working material and the extraction path comprises and an outlet path from the column.

According to a second preferred version of the first aspect of the present invention or the first preferred version thereof the oxidising gas is or includes ozone.

According to a third preferred version of the first aspect of the present invention or any preceding preferred version thereof the oxidising gas is generated locally outside the vessel and introduced into the vessel by an input path.

According to a first embodiment of the first preferred version the working material is generated by the application of a high voltage electrical discharge to a mixture of feedstock material with water.

According to a fourth preferred version of the first aspect of the present invention or any preceding preferred version thereof the method is characterised as being undertaken as a batch process.

According to a fifth preferred version of the first aspect of the resent invention or any of the preceding first to third preferred versions thereof the method is characterised as being undertaken as a continuous process.

According to a sixth preferred version of the first aspect of the present invention the method of the first preferred version or of any subsequent preferred version when reading on the first preferred version is characterised by the provision of cooling in the, or at least one, outlet path to condense a fraction passing along the path.

According to a seventh preferred version of the first aspect of the present invention the method of the first preferred version or of any subsequent preferred version when reading on the first preferred version is characterised by the provision of a further fractionating process wherein one of the product fractions from an outlet path are subjected to a further fractionating process comprising the steps of:

1 supplying the product fraction as a working material to a further vessel to provide a column of liquid working material;

2 directing an oxidising gas from a first location in the further vessel so as to provide for the oxidising gas to pass through the column with intimate mixing between the gas and the working material;

3 enabling one or more product fractions generated by chemical or physical interaction between the gas and the working material to pass out of the vessel by at least one further outlet path.

According to a second aspect of the present invention there is provided apparatus for treating a working medium comprising a hydrocarbon feedstock material including water characterised by;

1 a processing vessel defining a flow path for the working medium;

2 a gas dispensing means within the vessel for directing a flow of oxidising gas along the path to provide for intimate mixing between working medium in the path and the oxidising gas; and

3 means providing for a path for the removal of at least one product generated by chemical or physical interaction in the flow path between the gas and the working material to be withdrawn from the flowpath by way of an extraction path while allowing the remainder of the working medium to continue along the flow path.

According to a first preferred version of the second aspect of the present invention the apparatus includes:

1 a material generator of working material up-stream of the vessel adapted to receive a supply of the hydrocarbon source material and a supply of water and to provide for mixing thereof to generate a liquid working material; a material dispensing means within the vessel for providing in the vessel a column of working material from the material generator and a path there

through;

3 a gas dispensing means within the vessel for directing a flow of oxidising gas along the path to provide for intimate mixing between working material in the path and the oxidising gas; and

4 at least one outlet duct from the vessel whereby one or more fractions /products generated by chemical or physical interaction between the gas flow and the column of working material can be withdrawn from the vessel.

According to a second preferred version of the second aspect of the present invention as envisioned in the first preferred version thereof the apparatus is characterised in that the material generator comprises a mixing vessel wherein feedstock material and water are subjected to the application of a high voltage electrical discharge to provide the working material.

According to a third preferred version of the second aspect of the present invention as envisioned in the first or second preferred versions thereof the apparatus is characterised by a gas generator for oxidising gas which is an ozone gas generator located in the vicinity of the vessel.

According to a fourth preferred version of the second aspect of the present invention as envisioned in the first, second or third preferred version thereof is characterised by a condenser in the, or an, outlet duct from the vessel for condensing a volatile component of a fractionated product withdrawn from the vessel by the duct.

According toa fifth preferred version of the second aspect of the present invention as envisioned in any of the first to fourth preferred versions thereof the apparatus is characterised by a storage tank for a fraction from the, or an, outlet duct.

According to a sixth preferred version of the second aspect of the present invention as envisioned in the first to fifth preferred versions thereof the apparatus is characterised by at least two outlet ducts from the vessel and a plurality of storage tanks to receive directly or indirectly product supplied to each outlet duct together with transferring pipes lines and control means providing for the transfer of fractions

between tanks.

According to a seventh preferred version of the second aspect of the present invention as envisioned in the first to sixth preferred version thereof characterised by the inclusion of at least one further fractionating means having:

1 a further processing vessel:

2 a further working supply duct to receive either directly or indirectly material from the or an outlet from the processing vessel as further working material;

3 a further dispensing means within the further processing vessel providing for the establishment in the further vessel of a column of further working material and providing for a path through the further working column;

4 a second dispensing means within the further vessel for directing oxidising gas from a supply thereof along the path to provide for intimate mixing between working material in the path and oxidising gas;

5 at least one further outlet duct from the further vessel whereby one or more fractions and products generated by chemical or physical interaction between the gas and the working material can be withdrawn from the further vessel.

Typically the apparatus is characterised by storage tanks for fractions generated from the or each outlet duct and /or the or each further outlet duct. There can also be provided a plurality of storage tanks together with transferring pipes lines and control means providing for the transfer of fractions /products between the storage tanks.

BRIEF DESCRIPTION OF DRAWINGS

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings of which:

Figure 1 is a diagrammatic view of a conventional fractionating process;

Figure 2 is a sectional plan view of a pre-treatment processing stage for an oil refinery; and

Figure 3 is a diagrammatic view of a fractionating process vessel and of a plant incorporating the vessel both according to the present invention.

MODE FOR CARRYING OUT THE INVENTION

Figure 2

The drawing shows a vessel 11 adapted to receive by inlet 12 a working medium comprising a feedstock of crude oil and water. In this case the crude oil has a sulphur content which is higher than average and this process serves to optimise the feedstock for subsequent refining process and also the final product produced by the process. In addition the feedstock has a water content sufficient for the working medium to be treated to best effect as will be described hereafter. In the event the water content is not sufficient then further water can be introduced prior to the processing stage to be described to provide the appropriate water content in the feedstock.

The vessel 11 has an outlet 13 whereby the treated working medium from the vessel 11 is passed to the next stage in the process. The internal diameter Dl of inlet 12 and D2 of outlet 13 are one half the internal diameter D3 of process duct 14 defining a flow path F for the working medium.

An ozone generator 15 is located in the vicinity of the vessel 11 and receives a high voltage supply from a source 16 whereby a supply of ozone is generated. Ozone is fed from the generator 15 to the manifolds 17, 18, 19, 20 by way of outlet 21 and header 22.

Each manifold 17, 18, 19, 20 is used to supply a set of distribution nozzles. Typically manifold 18 supplies nozzles 23, 24, 25, 26. Similarly manifold 17 supplies nozzle sequence NI, manifold 19 supplies nozzle sequence N2 and manifold 20 supplies nozzle sequence N3.

In bottom limb 27 of the vessel 11 there is provided a withdrawal duct 28 whereby solid or very viscous material is withdrawn from medium in the flow path F. The treated working medium flows along the remainder of the flow path in the vessel 11 and then out of the vessel by way of outlet 13 to the next stage in the process (in this case a sequence of refining stages). Typically the removal of sulphur bearing material is of particular importance when subsequent stages arise making use of

catalysts liable to be damaged or at least rendered less effective by the existence of sulphur bearing compounds.

In operation working medium prepared at an earlier stage and comprising a hydrocarbon oil feedstock which includes water is fed into path F by way of inlet 12. The ozone generator 15 is then caused to provide a supply of ozone to be fed to the nozzles 23 to 26 and nozzle sequence NI to N3 so that the supplied ozone is caused to mix intimately with working medium in the flowpath F. The amount of ozone supplied is governed in accordance with the characteristics of the supplied working medium to the process and the desired characteristics in the to be obtained in the end product from this process stage. Experiment has shown that an ozone addition lying in the range 0.003 gr to 50 gr per kilogram of feed stock can be used to de- sulphur the incoming feedstock to a sufficient extent. As a consequence of simple deposition or agitation caused by the incoming ozone gas bubbles and / or chemical interaction between the ozone and constituents of the oil, solids such as sand or rock particles, sulphur bearing solids whether brought in by the feedstock or generated by chemical interaction of the ozone with flowing medium in flowpath F tend to be precipitated are withdrawn by way of withdrawal duct 28.

Apart from solids deposition the ozone also serves to generate gaseous liquid sulphur oxides which continue to be carried by the working medium as it passes out of the vessel 11 by outlet 13. If required a further processing stage can be used to adjust sulphur oxide levels or levels of other constituents can follow the process described.

The process described can be carried out at relatively low temperatures (say 20° C) and at atmospheric pressure and consequently there is no substantial requirement for heating, vessel insulation nor for the provision of high pressure processing vessels.

Working medium treated in the described process is found to improved for subsequent processing by reducing solid, very viscous or sulphur bearing content from the feedstock. Typically the working medium treated according to the present invention can be used as feedstock for a conventional fractionating process. For this purpose a working medium treated according to the present invention provides an

optimised feedstock enabling a conventional fractionating process to be operated more effectively and to produce an enhanced range of product fractions than would be possible from a raw feedstock not subject to the process of the present invention.

In another application a process stage according to the present invention can be used as a preliminary stage before utilising the fractionating method and apparatus described in our co-pending application 95 24221.

Figure 3

This shows a processing plant. It is emphasised that the diagram is intended to show the main components of the processes involved and the main functional relationships between them. It does not show all control features or relative sizes of components or quantitative features that would be required for an operational plant.

Attention is first drawn to a processing unit lying within boundary A lying generally in the upper and left hand side of Figure 3.

Processing unit

A process vessel 11 provides for batch process fractionation of a supply of hydrocarbons in the form of crude oil. The vessel 11 has in its upper part 11 A a first dispenser comprising an inlet manifold head 12 linked by a supply duct 13 to a mixing tank 14. The mixing tank 14 is fed a supply of crude oil feedstock from tank 15 by way of pipe 15 A; and a supply of water from tank 16 by way of pipe 16A. The mixing tank 14 has incorporated in it a pair of discharge electrodes providing a spark gap 17 coupled by line 18 to a high voltage generator 19 energised by way of a power transformer 20. The energy generated in the spark gap 17 serves to break down the feed stock material and promote mixing with the water supplied from tank 16. Pump P and pipes Pl, P2 provide for the circulation of the contents of the tank 14 to maintain a homogeneous product. A typical feedstock/ water mixture which provides a useful working material has the proportions of 80% feedstock to 20% water.

The process vessel 11 serves to establish a column 21 of the working material supplied to the vessel through inlet 12 by supply duct 13. The column 21 in

operation has a free surface 21'.

At lower section 11B of the vessel 11 there is provided a spray manifold 23 linked by a gas duct 24 to a compressor 25 which receives an oxidising gas supply from ozone generator 26. The generator 26 serves to generate ozone from atmospheric air using an electrical discharge powered by way of a generator 27. Hereafter 'ozone' should be taken to include not only ozone as such but also ozone mixed with other oxidising gases such as oxygen and also to include derivatives of ozone.

The process vessel 11 is equipped with four outlet ducts 28, 29, 30, 31 located at pre¬ determined levels relative to the surface level 21'. The fractionating process will be described in more detail hereafter. Briefly: outlet 28 is above the level 21' and serves as a take off for vapour evolved from the column 21; outlet 29 is just below the surface level 21' and serves as a take off for lighter liquid fractions; outlet 30 is at an intermediate level in the column 21 and serves as a take off for mid dense fractions; and outlet 31 at the bottom of the column serves to extract dense fractions and reaction products as will be outlined hereafter. The processing plant can be fabricated from any suitable material as long as the interior is rendered inert to the working material and to ozone.

When ozone gas is supplied to the spray manifold 23 from generator 26 the gas is released into the column 21 as a stream S of bubbles of controlled bubble size and at a pre-determined throughput. The bubbles in stream S rise freely up through the column 21. In this way the working material in column 21 and the ozone gas bubbles in stream S are readily brought into intimate contact with two particular results.

Firstly a physical action resulting in the working material undergoing fractionation due to the more volatile components in the working material being released from retention in the more viscous working material component. The description relating to the convention distillation system described in connection with Figure 1 described the use of boiling to promote the release of volatile fractions from a feed stock. In the

boiling situation the ebullition results in generation of bubbles of vapour which act to withdraw further quantities of vapour as they rise through the heated feedstock, ln the present case the bubbles, in this case of ozone, serve to enhance the overall fractionating effect.

Secondly a chemical action arising from the intense oxidising action of the ozone on available chemical components in the feedstock. The type and amount of these components vary in dependence on the source of the feedstock. Typically some feedstocks have a relatively high sulphur content. As described in connection with Figure 2 the oxidising effect of an ozone stream can be used to convert sulphur constituents to sulphurous compounds which can be readily extracted at subsequent stages in the process.

It has been found possible to operate the process of the present invention within vessel 11 at near ambient temperatures and pressures so not requiring extremes of temperature or pressure. This contrasts with conventional fractionating processes which apart from requiring the use of large scale distillation towers and local heating to relatively high temperatures also involve the use of dangerous materials such as hydrogen gas (in catalytic cracking plants) and relatively high pressure containment requirements.

In addition the power requirements for the process in vessel 11 are kept to a minimum involving electrical supplies to the generator 19 and the ozone powering generator 27. This requirement is contrasted with that of a conventional distillation part later in this specification.

Although the present invention is best utilised by an installation designed to take full advantage of its features it can be adapted for use with an existing fractionating system which can thus continue in use. Thus the above description refers to the use of a crude oil feedstock supply from tank 15 into the mixing tank 14. However if the working material is to be generated from a less dense material (such as the output from the first stage of an existing conventional distillation plant) then this less dense feedstock can be supplied as an initial feedstock to the tank 15. However it would still be expected to mix the feedstock with water in order to provide a readily

handled working material to the vessel 11 to form the column 21.

Processing installation

Consideration is now extended to that part of Figure 3 outside the boundary A. It will be seen that the process vessel 11 is incorporated into a processing plant enabling a range of products to be obtained from a given feedstock fractionated by way of vessel 11.

First outlet 28 from vessel 11 feeds into a duct 32 extending through a refrigerated condenser 33 providing for volatile components drawn off from vessel 11 to be condensed prior to passing into a storage tank 34. Outlet 35 from the tank 34 provides for condensed material to be passed to inlet 36 of a blending tank 37.

Second outlet 29 of vessel 11 supplies an inlet 38 of fractionating vessel 39 similar in function to vessel 11 described earlier. Feed material supplied to inlet 38 is sprayed into the vessel 39 by way of a manifold 40 to form a column 41 of hydrocarbon working material with a free surface 41'.

Gas manifold 42 enables a supply of ozone gas in duct 43 from generator 26 to be bubbled through the column 41 to provide for fractionation of working material in the column 41 along with oxidation as described above in connection with vessel 11 within boundary A.

Upper outlet 44 provide for vapours fractions released from column 41 to be drawn off by duct 45 to a pass through a refrigerating cooler 46 causing the volatile fraction to be condensed prior to passing into a holding tank 47. Outlet 48 from the tank 47 provides for condensed material to be passed by way of duct 49 to inlet 36 leading into blending tank 37.

Intermediate outlet 50 from vessel 39 provides for intermediate liquid fractions to be drawn from column 41 and fed into blending tank 37 by way of duct 51 and inlet 52.

Bottom outlet B from vessel 39 feeds an intermediate storage vessel 68 by way of a duct 69.

Third outlet 30 of vessel 11 supplies feedstock by way of duct 53 to fractionating vessel 54 similar in form and function to vessel 39 described earlier. Feed material supplied to inlet 55 is sprayed into the vessel 54 by way of a manifold 56 to form a column 57 of hydrocarbon working material with a free surface 58.

Gas manifold 59 enables a supply of ozone gas in duct 60 from generator 26 to be bubbled up through the column 57 to provide for fractionation of working material in the column 57 along with oxidation reactions as described above in connection with vessel 11 within boundary A.

Outlet 61 from vessel 54 provides for intermediate liquid fractions to be drawn off by way of duct 62 to be passed through inlet 63 into blending tank 37.

Outlet 64 from vessel 54 provides for residual fractions in the vessel 54 to be drawn off by way of duct 65 for holding in storage tank 66.

Fourth outlet 31 of vessel 11 feeds by way of duct 67 an intermediate storage vessel 68. This intermediate storage vessel 68 can supply storage tank 66 by way of duct 69'.

While the full advantages of the proposed fractionating system of the present invention are best achieved by the provision of a new installation it can also be installed as an intermediate stage in an existing plant to take advantage of available feedstocks or intermediate materials available upstream to the stage from the existing plant or to provide more cheaply a feedstock or intermediate product for utilisation downstream in the existing plant.

The power requirements of the installation described in connection with Figure 2 are low when compared with those of a conventional fractionating system. No extremes of temperature or pressure are called for.

The exemplary embodiment makes batch usage of the process in process vessel 11 by periodically supplying a column 21 of working material to which the process is applied. However it is envisaged that the process could also be undertaken on a continuous basis with a continuous flow of working material into the column and submitting it to the flow of ozone.

INDUSTRIAL APPLICABILITY

The present invention provides for a method of readily and economically making use of ozone to provide a preliminary treatment process for hydrocarbon feedstock material and for fractionating process for hydrocarbon materials. It provides a preliminary process and a fractionating process which can be carried out at near atmospheric temperatures and pressures without the need for significantly powerful heat sources. The preliminary treatment process can be used as a preliminary stage for a conventional fractionating plant so as to provide economically and readily a feedstock of optimised characteristics for the existing plant.

A consequence of the present invention is that installations for undertaking the preliminary and fractionation processes of the present invention for a given throughput are cheaper to build than conventional installations. They are also readily incorporated in existing processing plant.

The present invention not only provides plant with a relatively low initial capital cost when compared with a conventional plant but also with lower running costs. Typically the present process does not require the use of catalysts which are inherently expensive and liable to deteriorate when in use so requiring their periodic replacement or renovation.

The proposed process can be incorporated in an existing distillation based plant which can be used to provide for the provision of feedstock to the opening processing stage but also for the storage, mixing and circulation of product fractions following the production of product by means of the present process.

A comparison is now drawn between a conventional fractionation system making use of a heated feedstock in a distillation process and a system according to the present

invention utilising ozone gas or a derivative thereof (either alone or in an oxidising gas mixture).

Conventional system

A conventional distillation system for fractionation of a crude oil hydrocarbon feedstock involves a sequence of distillation columns at least some of which are required to operate at high pressure (of the order of 6 atmospheres) relative to atmospheric. Relatively high temperatures (typically 450° C) are required to initiate the distillation process. Energy and other requirements for a conventional catalytic cracking plant processes are substantial. Typically in order to treat 1 kg of feedstock there will be a need to use 12 - 40 kW of electricity, 1 cubic metre of hydrogen and the use of a catalyst such as, amongst others, platinum or nickel. There also need to be available a substantial amount of water for cooling and a typical plant requires water at the rate of 1 cubic meter for every 1 kilo of product.

Care needs to be observed in an operating process to avoid contamination of the catalyst which in any event needs periodic renewal.

Such conventional processes are well established with installations in many parts of the world. However both the capital cost of such an installation and its running costs are high by comparison with the proposed system of the present invention.

Finally there are ecological risks associated with conventional plant. Apart from the flammability of the hydrocarbon products produced by the distillation process the chances of site contamination are high quite apart from the dangers of using hydrogen gas and the consequences of leakage from high pressure locations.

Process of the present invention

In contrast to the conventional distillation system just referred to the process of the present invention does not rely on high temperature or pressure to achieve fractionation. It utilises ozone or an ozone derivative in a process undertaken at ambient temperatures and pressures to provide for fractionation of a working mixture derived from a feedstock which is initially hydrolysed. The degree of fractionation in a given process vessel is high and consequently the conventional

requirement for a sequence of distillation towers is avoided along with their use of high pressures and temperatures, hydrogen and a catalyst. It has also been found that fractionating achieved by the present invention results in an enhanced proportion of high octane content in the end product with a marked increase in alcohols when compared with the products of a conventional process. Furthermore the use of ozone and its derivatives to treat a hydrolysed working material results in fractionated products which are virtually sulphur free. In this way it becomes possible to make use of feedstocks whose sulphur content would be regarded as unduly high for processing in a conventional distillation plant. The process of the present invention provide for reactions leading to enhanced combustion characteristics in the resulting product fuels. Some of these ozone based reactions such as oxidation of an alkane (to give carbon dioxide and water) and the sulphonisation of SO molecules are exothermic. Some including the oxidation of hydrogen peroxide to give oxygen and water are endothermic.

For a given throughput a fractionating plant based on the present invention can be designed to occupy substantially less ground area than a convention distillation plant.

Energy and other requirements for this present process are much less than those referred to above in relation to the conventional process. Typically in order to treat 1 kg of feedstock there will be a need to use 3 - 4 KW of electricity. There is no requirement for hydrogen nor for a catalyst such as platinum. Water is required for hydrolysation at a rate of 0.2 litre per kilo of product. There is a need for a certain amount of refrigeration to condense more volatile components. There is no requirement for pressure vessels in order to undertake the fractionation process nor for means for maintaining a high temperature. As a consequence the capital cost and subsequent running costs of a plant based on the proposed process are substantially less than that of a conventional plant. As was pointed out in describing the exemplary embodiment it is possible to incorporate plant for the presently proposed process in an existing conventional distillation system so as to take advantage of parts of the existing installation and equipment without going to the expense of constructing an entirely new installation.

The process of the present invention while leading to the production of a flammable product is not in itself a source of ecological problems in comparison with those liable to arise with a conventional plant.

If an emergency arises requiring the shutting down of a process plant based on the present invention this is readily achieved by terminating the flow of ozone through the or each process vessel. This amounts to little more than switching off the or each ozone generator. This contrasts with the shutting down of a conventional system involving the need to undertake a sequence of steps and the passage of time before the process stops. If this is not undertaken with due care damage can be done to the plant requiring a subsequent cleaning down or repair stage before the plant can be started again.