Field of the Invention

The present invention relates to a process for treating a mixture comprising solid material and liquids comprising a first liquid and a second liquid, wherein the first and second liquids have different boiling points. The present invention also relates to a composition comprising a solid material and a second liquid obtainable by the process. Preferably the second liquid comprises an oil. The present invention also relates to the use of a composition comprising a solid material and oil as a fuel.

Background of the Invention

It is well-known in the art that hammer mills can be used to evaporate all liquids from a mixture of solids and liquids. When using such hammer mills, a dry fluidized bed is formed inside the stator due to the rotation of the rotor/hammers and transfer of heat by friction between the hammers and the solid material in the fluidized bed.

The bed will work satisfactorily when it is completely dry and may also work with a small amount of liquids remaining in the bed, i.e. liquids not being evaporated at the set process temperature. By adding some liquid to achieve a higher liquid to solids ratio, it has been experienced that, when treating some mixtures of solids and liquids, the bed will act as a “dough”, i.e. a very highly viscous mixture of solids and liquids, and create unbalance and problems in the process such as, for example, vibration problems and overheating of the hammer mill. In the “dough phase”, the heat transfer will be low since much of the surface area in the dry fluidized bed will no longer be available.

It would be desirable to provide a process in which other types of mixtures of solids and liquids can be treated, e.g. by using a hammer mill. It would also be desirable to provide a process in which the dough phase problems are prevented or, if they would occur, eliminated or at least substantially limited. It would also be desirable to provide a process in which the risks associated with dough phase formation, such as vibrations and/or overheating of the reactor or equipment used, are avoided or mitigated, e.g. when using a hammer mill for carrying out the process. Summary of the Invention

It is accordingly an object of the present invention to provide a process for treating a mixture of solid material and liquids such as, for example, drill cuttings from the oil industry, and sludge obtained from water treatment or waste water treatment generated from biological and/or chemical processes, wherein the sludge may contain and/or be contaminated by oil, and mixtures thereof.

It is another object of the present invention to provide a process for treating such a mixture in which the problems associated with dough phase formation are prevented or, if they would occur, eliminated or at least substantially limited.

It is yet another object of the present invention to provide a process fortreating such a mixture in which the risks associated with dough phase formation, such as vibrations and/or overheating of the reactor or equipment used, are avoided or mitigated.

It is yet another object of the present invention to provide a process for treating a mixture of solid material and at least two liquids in order to separate one of the liquids from the mixture to provide one of the liquids, e.g. in an essentially pure form, and a mixture comprising solid material and the other liquid.

Further, it is another object of the present invention to provide a mixture of solid material and liquid obtained I obtainable by the process of the invention. It is yet another object of the present invention is to provide one or more uses of the mixture of solid material and liquid obtained I obtainable by the process.

By using the process of the invention, it is possible to treat a mixture of solid material and liquids having different boiling points. Examples of mixtures that can be treated include drill cuttings from the oil industry which may contain water, oil and organic and/or inorganic solids, and sludge obtained from water treatment or waste water treatment generated from biological and/or chemical processes, wherein the sludge may contain and/or be contaminated by oil, and mixtures thereof.

By using the process of the invention, it is possible to separate water from the mixture, thereby providing a mixture of oil and organic and/or inorganic solids which may be used as a fuel, preferably without further processing or purification. Hereby the present invention provides an improved and simplified process for separating one of the liquids from such a mixture, and a simplified process for the production of an oil-based fuel, which lead to environmental and economic benefits and increased productivity.

The present invention also provides an oil-based product obtained by the process, and the use of the oil-based product as a fuel. Hereby the present invention provides a valuable product and the use the thereof in valuable applications.

Accordingly, in one aspect, the present invention relates to a process for treating a mixture comprising solid material and liquids comprising a first liquid and a second liquid having different boiling points in a reactor, wherein the process is carried out in a hammer mill, wherein the reactor comprises a cylindrical reactor chamber, a rotor shaft equipped with radially extending fluidization or mixing units disposed in the reactor chamber, the rotor shaft being connected to a drive unit for rotation of the rotor shaft, one or more inlets for feeding the mixture, solid material and/or one or more liquids comprising the first liquid and/or the second liquid into the reactor chamber, and one or more outlets for discharging of solid material, liquids, gases and vapour from the reactor chamber, and wherein the process comprises the steps of:

(i) keeping the mixture in the reactor chamber;

(ii) rotating the rotor shaft to generate heat by friction to the mixture;

(iii) running the process at a temperature which is at or above the boiling point of the first liquid and below the boiling point of the second liquid to evaporate the first liquid;

(iv) discharging the evaporated first liquid out of the reactor chamber; and

(v) discharging a mixture comprising the solid material and second liquid out of the reactor chamber.

In another aspect, the present invention relates to a composition comprising a solid material and a second liquid obtainable by the process of the invention. Preferably the second liquid comprises oil.

In yet another aspect, the present invention relates to use of a composition comprising a solid material and oil as a fuel.

These and other objects and aspects of the invention will be described in further detail hereinafter. Brief Description of the Drawings

Fig. 1 shows a reactor for use in the process according to the invention.

Fig. 2 is an open-ended view showing a reactor chamber of the reactor. Fig. 3 shows a cross-sectional view of the reactor.

Detailed Description of the Invention

The present invention relates to a process which comprises treating a mixture comprising solid material and liquids comprising a first liquid and a second liquid having different boiling points. The term “the mixture of the invention”, as used herein, refers to the mixture comprising solid material and liquids comprising a first liquid and a second liquid having different boiling points. The term “the liquids of the invention”, as used herein, refers to the liquids comprising a first liquid and a second liquid having different boiling points. The term “composition of the invention”, as used herein, refers to a composition or mixture comprising the solid material and second liquid obtainable by the process of the invention.

The solid material may comprise one or more inorganic solid materials, one or more organic solid materials, and mixtures thereof. The one or more inorganic solid materials may comprise mineral solid materials, sand, and mixtures thereof. Examples of suitable inorganic solid materials include inorganic materials comprising one or more cations selected from sodium, potassium, ammonium, aluminium, iron, copper, zinc, vanadium, nickel, arsenic, cadmium, chromium, mercury, lead and manganese, and one or more anions selected from sulphur, sulphate, chloride, fluoride, nitrate, and phosphate. The one or more organic solid materials may comprise solid hydrocarbons and aromatic compounds, solid biomass, e.g. sludge obtained from water treatment or waste water treatment generated from biological and/or chemical processes, and mixtures thereof.

Preferably, as regards the liquids of the invention, the boiling point of the first liquid is lower than the boiling point of the second liquid, i.e. the boiling point of the second liquid is higher than the boiling point of the first liquid. When the liquids of the invention comprise three of more liquids, e.g. first liquid, second liquid, third liquid, fourth liquid, etc., the boiling point of the first liquid is preferably lower than the boiling points of the other liquids, including the second liquid, third liquid, fourth liquid, etc., i.e. the boiling points of the second liquid, third liquid, fourth liquid, etc. are preferably higher than the boiling point of the first liquid. Preferably, the liquids of the invention comprise water and oil. Preferably, the first liquid is water, and the second liquid is oil, wherein the boiling point of water is lower than the boiling point of the oil. The oil may be selected from crude oil, different oil fractions, including oils having carbon chain lengths of at least 14 carbon atoms, e.g. C14 to C40 or even higher, and mixtures thereof, all having a boiling point which is higher than the boiling point of water.

In the process of the invention, the mixture of the invention may comprise solid material and liquids, or liquids of the invention, in amounts that vary within wide limits depending on, for example, the type of mixture used, type of reactor used, etc. Usually, the amount of solid material is at least 1 % by weight, suitably at least 3% by weight, and preferably at least 5% by weight, based on the weight of the mixture. The amount of solid material may be up to 50% by weight or higher, suitably up to 30% by weight and preferably up to 15% by weight, based on the weight of the mixture.

The reactor 10 according to the invention comprises a cylindrical reactor chamber 12, a rotor shaft 14 equipped with radially extending fluidization or mixing units 16 disposed in the reactor chamber 12, the rotor shaft 14 being connected to a drive unit for rotation of the rotor shaft 14, one or more inlets 22 for feeding the mixture of the invention, solid material and/or one or more liquids of the invention comprising the first liquid and/or the second liquid into the reactor chamber 12, and one or more outlets 18,20 for discharging of the mixture obtained by the process of the invention, solid material, one or more liquids comprising the first liquid and/or the second liquid, gases and/or vapour, e.g. evaporated first liquid, from the reactor chamber 12. The fluidization or mixing units 16 may comprise hammers, knives, blades, wings or disks, preferably hammers. The fluidization units 16 may be of equal length, or optionally of alternating lengths. The reactor 10 of the invention may be part of a hammer mill and, preferably, the process is carried out in a hammer mill. Preferably, the reaction chamber 12 comprises a wet bed comprising the solid material and the liquids comprising the first liquid and the second liquid.

The process comprises keeping the mixture of the invention in the reactor chamber 12, and the mixture of the invention may be kept at a fill level in the reactor chamber that may vary depending on, for example, the desired production or productivity. The mixture of the invention may be kept in the reactor chamber at a fill level of from 10%, suitably from 20% and preferably from 30% of the reactor chamber volume, and the mixture of the invention may be kept in the reactor chamber at a fill level of up to 95%, suitably up to 85% and preferably up to 80% of the reactor chamber volume.

The process of the invention comprises rotating the rotor shaft 14 to generate heat by friction to the mixture of the invention. Suitably, the process comprises rotating the rotor shaft at a speed of at least 350 rpm, preferably at least 400 rpm, and the speed may be up to 900 rpm, preferably up to 700 rpm, and usually the speed is about 630 rpm. The process of the invention may also comprise keeping or running hammers, knives, wings or disks of the fluidization or mixing units 16 at a peripheral speed of at least 15 m/s, suitably at least 25 m/s, preferably at least 28 m/s, and the speed may be up to 50 m/s, suitably up to 45 m/s, preferably up to 40 m/s.

The second liquid, optionally together with any third liquid, fourth liquid, etc., may be present in the reactor chamber in an amount of at least 8% by weight, suitably at least 15% by weight, preferably at least 18% by weight, based on the weight of the solid material, and the amount may be up to 300% by weight or even higher, suitably up to 200% by weight, preferably up to 150% by weight, based on the weight of the solid material. According to the invention, the process preferably comprises continuously or intermittently feeding second liquid to the mixture present in the reactor chamber. This may be beneficial in order to retain second liquid in the process and/or keep the amount of the second liquid at a desired level.

The process of the invention is preferably conducted at a temperature which is at or above the boiling point of the first liquid to evaporate at least part of the first liquid. Preferably, a substantial amount, all or essentially all of the first liquid is evaporated. The process is preferably conducted at a temperature which is below the boiling point of the second liquid. Preferably, no, essentially no or a small amount of second liquid is evaporated at the temperature of the process. The process may be conducted at a temperature in the range of from 0°C to 50°C above the boiling point of the first liquid, suitably in the range of from 10°C to 30°C above the boiling point of the first liquid, preferably at a temperature of about 20°C above the boiling point of the first liquid, and below the boiling point of the second liquid. When the first liquid is water, the process may be conducted at a temperature in the range of from 100°C to 150°C, suitable in the range of from 110°C to 130°C, and preferably at a temperature about 120°C.

According to the invention, the process may be conducted at atmospheric or ambient pressure, super-atmospheric pressure or sub-atmospheric pressure depending on, for example, the type of reactor used, the liquids of the invention, and the desired degree of separation of the liquids, etc.

The process of the invention comprises rotating the rotor shaft 14 at a certain speed, and optionally keeping or running the hammers, knives, wings or disks of the fluidization or mixing units 16 at a certain peripheral speed, to generate heat by friction to the mixture of the invention. If desired, further (external) heating or cooling of the reactor and/or reactor chamber may take place to achieve the temperature as defined above for conducting the process. Such heating or cooling of the reactor and/or reactor chamber may take place according to conventional methods well-known in the art. However, the process is preferably conducted without further heating or cooling of the reactor and/or reactor chamber.

The process of the invention comprises discharging evaporated first liquid out of the reactor chamber 12. The process of the invention also comprises discharging the mixture comprising the solid material and second liquid out of the reactor chamber 12. Suitable equipment, e.g. one or more pumps, screws, extruders, locks, and mixtures thereof, which are conventional and well-known in the art, may be used for discharging the evaporated first liquid out of the reactor chamber 12 and/or for discharging the mixture comprising the solid material and second liquid out of the reactor chamber 12.

Evaporated first liquid that is discharged out of the reactor chamber may be fed to a condensation unit, where condensed first liquid is collected. Any second liquid that is evaporated and discharged out of the reactor chamber 12, may be fed to a condensation unit, usually the same condensation unit to which the first liquid is fed, where the second liquid is separated from the first liquid, and the second liquid is preferably recirculated back to the reactor chamber. Separation of the first liquid and second liquid may be carried out by conventional methods know in the art, e.g. phase separation, evaporation, distillation, etc.

According to the invention, the process may comprise continuously or intermittently feeding first liquid and/or second liquid to the mixture present in the reactor chamber. This may be beneficial in orderto keep the amount of liquids of the invention at a desired level. Preferably, the process comprises continuously or intermittently feeding second liquid to the mixture present in the reactor chamber. Continuously or intermittently feeding second liquid to the mixture may be beneficial in order to retain second liquid in the process and/or keep the amount of the second liquid at a desired level. The first liquid and/or second liquid may be fed to the reactor chamber by means of any suitable equipment, e.g. one or more pumps, screws, extruders, locks, and mixtures thereof, which are conventional and well-known in the art.

The mixture comprising the solid material and second liquid obtained or obtainable by the process of the invention may have a composition that may vary within wide limits depending on, for example, the mixture of the invention, the liquids of the invention, whether and to what extent further amount(s) of first liquid and/or second liquid has/have been fed to the reactor chamber, to what extent first liquid has been separated from the mixture and/or second liquid, etc. Preferably, the mixture obtained or obtainable by the process has content of the first liquid which is low, usually below 10% by weight, suitable below 5% by weight, and preferably below 1 % by weight, or below 0.5% by weight, or below 0.1 % by weight. When the first liquid is water, the mixture obtained or obtainable by the process may be seen as a semi-dried, substantially dried or completely dried mixture comprising solid material and second liquid, e.g. oil.

Further, the mixture comprising the solid material and second liquid obtained or obtainable by the process of the invention may contain the second liquid in an amount of at least 8% by weight, suitably at least 15% by weight, and preferably at least 18% by weight, based on the weight of the solid material, and the mixture may contain the second liquid in an amount of up to 300% by weight or even higher, suitably up to 200% by weight, and preferably up to 150% by weight, based on the weight of the solid material.

The process of the invention preferably comprises feeding further mixture comprising the solid material and the liquids comprising first liquid and second liquid to the reactor chamber. The mixture may be fed to the reactor chamber by means of any suitable equipment, e.g. one or more pumps, screws, extruders, locks, and mixtures thereof, which are conventional and well-known in the art. Preferably, the process is conducted in the presence of a gas selected from air, inert gas, and mixtures thereof, suitably in the presence of air or nitrogen gas.

According to the invention, the process preferably comprises continuously or intermittently feeding the mixture comprising solid material and liquids comprising first liquid and second liquid to the reactor chamber, and continuously or intermittently discharging the evaporated first liquid and the mixture comprising solid material and second liquid out of the reactor chamber. Starting the process preferably comprises first feeding the solid material to the reactor chamber, and then feeding the liquids comprising the first liquid and the second liquid to the reactor chamber. The mixture obtained in the reaction chamber may comprise from 1 to 50% by weight, suitably from 3 to 30% by weight, preferably from 5 to 15% by weight of solid material and from 50 to 99% by weight, suitably from 70 to 97% by weight, preferably from 85% by weight to 95% by weight of liquids. Thereafter, the process preferably comprises continuously or intermittently feeding the mixture comprising solid material and liquids comprising first liquid and second liquid to the reactor chamber and/or continuously or intermittently feeding additional second liquid.

The process of the invention preferably comprises treating the mixture comprising solid material and liquids comprising a first liquid and a second liquid having different boiling points to separate and/or remove the first liquid, or at least part thereof, from the solid material and the second liquid. The process further comprises discharging the mixture comprising the solid material and second liquid out of the reactor chamber 12, and the invention further relates to the mixture comprising solid material and the second liquid obtainable by the process of the invention, i.e. the composition of the invention. Preferably, the composition of the invention comprises the solid material and a second liquid being an oil as defined above, and may have contents of solid material, including inorganic and/or organic solid materials, and liquids, including first liquid and second liquid, as defined.

The composition of the invention may be used in many applications, in particular when the second liquid comprises an oil, and the present invention further relates to the use of the composition of the invention as a fuel, preferably as a fuel for an engine of a ship, for producing hot water and/or steam for production of electricity.

Examples

The invention is further illustrated in the following examples which, however, are not intended to limit the same. Parts and % relate to parts by weight and % by weight, respectively, unless otherwise stated.

Example 1

A process according to the invention was carried out using a mixture consisting of biological sludge from biological water treatment process. The biological sludge, which was polluted by oil in the range of C14 - C ₂ e, had the following composition:

Water: 81 % by weight

Solid material: 8% by weight

Oil: 11 % by weight

The process was carried out in a hammer mill having a reactor with the following characteristics:

31 Hammers

70 Hammertips

Length of inside reactor 1000 mm

Diameter inside reactor 1100 mm

Further, the process was carried out at a temperature of 120°C and atmospheric or ambient pressure, wherein the rotor shaft was rotating at a speed of 630 rpm, and wherein additional mixture, water and/oil was fed to the reactor chamber during the process such that the amount of oil was about 50% by weight, based on the weight of the solid material, and the mixture had a content of water of about 86% by weight. The process according to the invention was successfully carried out and no technical problems were observed during the process.

Example 2

In this example, a process according to the invention was carried out similar to the process of Example 1 , except that the temperature was 124°C, the amount of oil was about 18% by weight, based on the weight of the solid material, and the mixture had a content of water of about 82% by weight.

This process according to the invention was also successfully carried out no technical problems were observed during the process.