Field of the invention

The invention relates to a method for drying particulate material such as hydrocarbonous particulate material, for example oil shale, as defined in the preamble of independent claim 1.

The invention also relates to an arrangement for drying particulate material such as hydrocarbonous particulate material, for example oil shale, as defined in the preamble of independent claim 13.

The invention relates also to the use of the method or to the use of the arrangement as defined in claim 25.

The invention relates especially to drying of hydrocarbonous particulate material in the form of shale oil. The method and arrangement of the invention can however also be utilized for drying other kind of particulate matter.

Especially when drying particulate material in the form of hydrocarbonous particulate material by means of a venturi dryer a risk is present that particulate material falls from the drying section of the venturi dryer through the venturi throat into the gas feeding section of the venturi dryer, where the temperature is relative high, for example 400 to 500°C. This high temperature causes the temperature of the particulate material present in the gas feeding section of the venturi dryer to raise i.e. to causing the hydrocarbonous particulate material to overheat and consequently to cause hydrocarbon and/or CO emissions.

Objective of the invention

The object of the invention is to provide a method and an arrangement for drying particulate material such as hydrocarbonous particulate material, for example oil shale, that lowers the risk to cause undesired emissions.

Short description of the invention

The method for drying particulate material such as hydrocarbonous particulate material, for example oil shale, of the invention is characterized by the definitions of independent claim 1.

Preferred embodiments of the method are defined in the dependent claims 2 to 12.

The arrangement for drying particulate material such as hydrocarbonous particulate material, for example oil shale, of the invention is correspondingly characterized by the definitions of independent claim 13.

Preferred embodiments of the arrangement are defined in the dependent claims 14 to 24.

The invention relates also to the use of the method as defined in any of the claims 1 to 12 or the arrangement as defined in any of the claims 13 to 24 for drying particulate material in the form of shale oil as defined in claim 25. The invention is based on the idea of feeding particulate material at several points into the drying section of the venturi dryer. This leads to a more even distribution of particulate material in the drying section of the venturi dryer, which in turn lowers the risk that particulate material falls from the drying section of the venturi dryer through the venturi throat into the gas feeding section of the venturi dryer.

In a preferred embodiment of the invention the screw feeders are connected to the drying section of the venturi dryer at feeding openings so that the central axis of the venturi dryer is uncut by imaginary extension of the rotation axis of the screw feeders. The advantage of this is that particulate material is not directed towards the middle of the inner space of the drying section of the venturi dryer where it can fall into the venturi throat.

In a preferred embodiment of the invention the screw feeders are connected to the drying section of the venturi dryer at feeding openings so that the feeding openings at which the screw feeders opens into the drying section of the venturi dryer are provided symmetrically with respect to the central axis of the venturi dryer. This leads to an even distribution of particulate material in the drying section of the venturi dryer, because the feeding openings are situated as far as possible from each other.

List of figures

In the following the invention will described in more detail by referring to the figures, of which

Figure 1 is a principle sketch of an embodiment of the arrangement,

Figure 2 shows a configuration of section A- A in figure 1,

Figure 3 shows another configuration of section A-A in figure 1,

Figure 4 shows yet another configuration of section A-A in figure 1, and

Figure 5 shows still another configuration of section A-A in figure 1.

Detailed description of the invention

The figures show examples of methods and apparatuses for drying particulate material such as hydrocarbonous particulate material, for example oil shale.

First the method for drying particulate material such as hydrocarbonous particulate material, for example oil shale, and some preferred embodiments and variants of the method will be described in greater detail.

The method comprises a providing step for providing a venturi dryer 1 having a venturi throat 2 and a drying section 3 in fluid connection with the venturi throat 2, and for providing a material feeding means 4 for feeding particulate material 10 from a particulate material source 5 into the drying section 3 of the venturi dryer 1, wherein the venturi dryer 1 having an inner space

(not marked with a reference numeral) symmetrical with respect to a central axis B of the inner space of the venturi dryer 1. The method comprises a material feeding step for feeding particulate material 10 from the particulate material source 5 into the drying section 3 of the venturi dryer by means of the material feeding means 4.

The method comprises a gas feeding step for feeding gas 11 from a gas feeding section 9 of the venturi dryer 1 through the venturi throat 2 of the venturi dryer 1 into the drying section 3 of the venturi dryer 1 and through particulate material 10 in the drying section 3 of the venturi dryer 1. The gas 11 can for example be hot gas containing oxygen. The gas 11 can for example be flue gas originating from a combustion process (not shown in the figures).

The gas feeding step may include feeding gas 11 from a gas source (not shown in the drawings) into the gas feeding section 9 of the venturi dryer 1.

The gas 11 that is fed in the gas feeding step may have a temperature between 400 and 500°C, for example about 450°C.

The particulate material 10 that is fed in the material feeding step from the particulate material source 5 may have a temperature of about 20°C or the temperature of the ambient air surrounding the particulate material source 5.

The temperature in the drying section 3 of the venturi dryer 1 may be between 100 °C and 200°C, for example 150°C.

The providing step includes providing a material feeding means 4 comprising at least two screw feeders 6 each comprising a spiral blade 7 rotatable about a rotation axis C so as to feed particulate material 10 by rotating the spiral blade 7 about the rotation axis C from a particulate material source 5 to the drying section 3 of the venturi dryer 1.

The method comprises connecting each of said at least two screw feeders 6 to the drying section 3 of the venturi dryer 1 so that each of said at least two screw feeders 6 opening up into the drying section 3 of the venturi dryer 1 at a feeding opening 8 between the screw feeder 6 and the drying section 3 of the venturi dryer 1.

The material feeding step includes rotating the spiral blade 7 of each of said at least two screw feeders 6 about the rotation axis C of respective screw feeder 6 to feed feeding particulate material 10 from a particulate material source 5 into the drying section 3 of the venturi dryer 1.

From the drying section 3 of the venturi dryer dried particulate material and gas may be fed to separation means (not shown in the figures) for separating gas from dried particulate material. The separation means can for example comprise gas-solid separation means such as a cyclone, an electrostatic precipitator, a bag filter or a candle filter.

The method includes preferably, but not necessarily, connecting at least one of said at least two screw feeders 6 to the drying section 3 of the venturi dryer so that the central axis B of the inner space of the venturi dryer lis uncut by an imaginary extension 12 of the rotation axis C of said at least one screw feeder 6 of said at least two screw feeders 6.

The method includes preferably, but not necessarily, connecting each of said at least two screw feeders 6 to the drying section 3 of the venturi dryer so that the central axis B of the inner space of the venturi dryer lis uncut by an imaginary extension 12 of the rotation axis C of each screw feeder 6.

The method includes preferably, but not necessarily, connecting each of said at least two screw feeders 6 to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 at which said at least two screw feeders 6 opens into the drying section 3 of the venturi dryer 1 are provided symmetrically with respect to the central axis B of the inner space of the venturi dryer 1.

The providing step may, as shown in the embodiment shown in figure 2, include providing a material feeding means 4 comprising two screw feeders 6 each comprising a spiral blade 7 rotatable about a rotation axis C. This embodiment of the method comprises connecting the two screw feeders 6 to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned under 120 degrees, preferably under 90 degrees, with respect to each other about the central axis B of the inner space of the venturi dryer 1.

The providing step may, as shown in the embodiment shown in figure 3, include providing a material feeding means 4 comprising two screw feeders 6 each comprising a spiral blade 7 rotatable about a rotation axis C. This embodiment of the method comprises connecting the two screw feeders 6 to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned substantially 180 degrees with respect to each other about the central axis B of the inner space of the venturi dryer 1.

The providing step may, as shown in the embodiment shown in figure 4, include providing a material feeding means 4 comprising three screw feeders 6 each comprising a spiral blade 7 rotatable about a rotation axis C. This embodiment of the method comprises connecting the three screw feeders 6 to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned substantially 120 degrees with respect to each other about the central axis B of the inner space of the venturi dryer 1.

The providing step may, as shown in the embodiment shown in figure 5, include providing a material feeding means 4 comprising four screw feeders 6 each comprising a spiral blade 7 rotatable about an rotation axis C. This embodiment of the method comprises connecting the four screw feeders 6 to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned substantially 90 degrees with respect to each other about the central axis B of the inner space of the venturi dryer 1.

The method includes preferably, but not necessarily, connecting each of said at least two screw feeders 6 to the drying section 3 of the venturi dryer 1 so that each of the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer are positioned substantially at the same position along the central axis B of the inner space of the venturi dryer 1.

The method includes preferably, but not necessarily, connecting each of said at least two screw feeders 6 to the drying section 3 of the venturi dryer 1 so that each of the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned substantially at the same vertical level i.e. height of the drying section 3 of the venturi dryer 1.

In an embodiment of the method, the providing step includes providing at least one screw feeder 6 having a right-handed spiral blade 7 and rotating said right-handed spiral blade 7 of at least one screw feeder 6 anti-clockwise in the material feeding step In this embodiment of the method, the providing step includes providing at least one screw feeder 6 having a left-handed spiral blade 7 and by rotating said left-handed spiral blade 7 of at least one screw feeder 6 clockwise in the material feeding step. This embodiment of the method includes preferably, but not necessarily, connecting said at least one screw feeder 6 having a right-handed spiral blade 7 to the drying section 3 of the venturi dryer 1 and connecting said at least one screw feeder 6 having a left-handed spiral blade 7 to the drying section 3 of the venturi dryer 1 so that both said at least one screw feeder 6 having a right-handed spiral blade 7 and said at least one screw feeder 6 having a left-handed spiral blade 7 feed particulate material 10 into the drying section 3 of the venturi dryer 1 at the side of the feeding opening 8 between respective screw feeder 6 and the drying section 3 of the venturi dryer 1 that is at a greater distance from the central axis B of the inner space of the venturi dryer 1 than the other side of the feeding opening 8 between respective screw feeder 6 and the drying section 3 of the venturi dryer 1. In this embodiment particulate material 10 is therefore fed into the drying section 3 of the venturi dryer 1 at locations being as far as possible from each other. On the other hand, if the number of the screw feeders is three, as in fig 4, or four, as in fig 5, all the screw feeders 6 could either have a left-handed spiral blade 7 or a right-handed spiral blade 7. On the other hand, if the number of the screw feeders 6 is four, as in fig 5, the screw feeders 6 could be arranged in pairs so that material feeding means 4 for feeding particulate material 10 from a particulate material source 5 into the drying section 3 of the venturi dryer 1 have two screw feeders having a left-handed spiral blade 7 and two screw feeders having a right-handed spiral blade 7.

The control of an electric motor (not shown in the drawings) for rotation of a left-handed spiral blade 7 of a screw feeder 6 or of an electric motor (not shown in the drawings) for rotation of a right-handed spiral blade 7 of a screw feeder 6 can for example be done by means of an electronic steering means (not shown in the drawings) comprising an encoder (not shown in the drawings). A such electronic steering means may provide for phase shifting steering the rotation direction and rotation speed.

The method includes preferably, but not necessarily, connecting each of said at least two screw feeders 6 to the drying section 3 of the venturi dryer 1 so that the rotation axis C of said at least two screw feeders 6 extends in a mirror-like manner in relation to each other with respect to a plane (not shown in the drawings) extending in the direction of the central axis B of the inner space of the venturi dryer 1. A such embodiment is shown in figure 2 and in figure 4.

Next the arrangement for drying particulate material such as hydrocarbonous particulate material for example oil shale an some embodiments and variants thereof will be described in greater detail.

The arrangement comprises a venturi dryer 1 having a venturi throat 2 and a drying section 3 in fluid connection with the venturi throat 2, and wherein the venturi dryer 1 having an inner space that is symmetrical with respect to a central axis B.

The arrangement comprises material feeding means 4 for feeding particulate material 10 from a particulate material source 5 into the drying section 3 of the venturi dryer 1.

The venturi dryer 1 comprises gas feeding section 9 for feeding gas 11 through the venturi throat 2 of the venturi dryer 1 into the drying section 3 of the venturi dryer 1.

The arrangement may include a gas source (not shown in the drawings) in fluid connection with the gas feeding section 9 of the venturi dryer 1.

The material feeding means 4 for feeding particulate material 10 from a particulate material source 5 into the drying section 3 of the venturi dryer 1 comprises at least two screw feeders 6 comprising a spiral blade 7 rotatable about an rotation axis C so as to feed particulate material 10 from a particulate material source 5 to the drying section 3 of the venturi dryer 1.

Each of said at least two screw feeders 6 opening up into the drying section 3 of the venturi dryer 1 at a feeding opening 8 between the screw feeder 6 and the drying section 3 of the venturi dryer 1.

At least one of said at least two screw feeders 6 is preferably, but not necessarily, connected to the drying section 3 of the venturi dryer 1 so that the central axis B of the inner space of the venturi dryer lis uncut by an imaginary extension 12 of the rotation axis of said at least one screw feeder 6 of said at least two screw feeders 6.

Each screw feeder 6 of said arrangement is preferably, but not necessarily, connected to the drying section 3 of the venturi dryer 1 so that the central axis B of the venturi dryer is uncut by an imaginary extension 12 of the rotation axis C of a screw feeder 6.

The feeding openings 8 at which each of said at least two screw feeders 6 opens into the drying section 3 of the venturi dryer 1 is preferably, but not necessarily, provided symmetrically with respect to the central axis B of the inner space of the venturi dryer 1.

The material feeding means 4 of the arrangement may, as shown in figure 3, comprise two screw feeders 6 each comprising a spiral blade 7 rotatable about an rotation axis C, and the two screw feeders 6 may be connected to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned under 120 degrees, preferably under 90 degrees, with respect to each other about the central axis B of the venturi dryer.

The material feeding means 4 of the arrangement may, as shown in figure 3, comprise two screw feeders 6 each comprising a spiral blade 7 rotatable about an rotation axis C, and the two screw feeders 6 may be connected to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned substantially 180 degrees with respect to each other about the central axis B of the venturi dryer.

The material feeding means 4 of the arrangement may, as shown in figure 4, comprise three screw feeders 6 comprising a spiral blade 7 rotatable about an rotation axis C, and the three screw feeders 6 may be connected to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned substantially 120 degrees with respect to each other about the central axis B of the inner space of the venturi dryer 1.

The material feeding means 4 of the arrangement may, as shown in figure 5, comprise four screw feeders 6 comprising a spiral blade 7 rotatable about an rotation axis C, and the four screw feeders 6 may be connected to the drying section 3 of the venturi dryer 1 so that the feeding openings 8 between each screw feeder 6 and the drying section 3 of the venturi dryer 1 are positioned substantially 90 degrees with respect to each other about the central axis B of the venturi dryer.

Each screw feeder 6 of the arrangement is preferably, but not necessarily, connected to the drying section 3 of the venturi dryer 1 so that each of the feeding openings 8 are positioned substantially at the same position along the central axis B of the inner space of the venturi dryer 1.

Each screw feeder 6 of the arrangement are preferably, but not necessarily, connected to the drying section 3 of the venturi dryer 1 so that each of the feeding openings 8 are positioned substantially at the same vertical level i.e. height of the drying section 3 of the venturi dryer 1.

The material feeding means 4 for feeding particulate material 10 from a particulate material source 5 into the drying section 3 of the venturi dryer 1 comprises in an embodiment of the arrangement at least one screw feeder 6 having a right-handed spiral blade 7, and at least one screw feeder 6 having a left-handed spiral blade 7 . In this embodiment of the arrangement, said at least one screw feeder 6 having a right-handed spiral blade 7 is preferably, but not necessarily, connected to the drying section 3 of the venturi dryer 1 and said at least one screw feeder 6 having a left-handed spiral blade 7 is preferably, but not necessarily, connected to the drying section 3 of the venturi dryer 1 so that both said at least one screw feeder 6 having a right-handed spiral blade 7 and said at least one screw feeder 6 having a left-handed spiral blade 7 is configured to feed particulate material 10 into the drying section 3 of the venturi dryer 1 at the side of the feeding opening 8 between respective screw feeder 6 and the drying section 3 of the venturi dryer 1 that is at a greater distance from the central axis B of the inner space of the venturi dryer lthan the other side of the feeding opening 8 between respective screw feeder 6 and the drying section 3 of the venturi dryer 1. On the other hand, if the number of the screw feeders is three, as in fig 4, or four, as in fig 5, all the screw feeders 6 could either have a left-handed spiral blade 7 or a right-handed spiral blade 7. On the other hand, if the number of the screw feeders is four, as in fig 5, the screw feeders 6 could be arranged in pairs so that material feeding means 4 for feeding particulate material 10 from a particulate material source 5 into the drying section 3 of the venturi dryer 1 have two screw feeders having a left-handed spiral blade 7 and two screw feeders having a right-handed spiral blade 7.

The control of an electric motor (not shown in the drawings) for rotation of a left-handed spiral blade 7 of a screw feeder 6 or of an electric motor (not shown in the drawings) for rotation of a right-handed spiral blade 7 of a screw feeder 6 can for example be done by means of an electronic steering means (not shown in the drawings) comprising an encoder (not shown in the drawings). A such electronic steering means may provide for phase shifting steering the rotation direction and rotation speed.

In the arrangement the rotation axis of said at least two screw feeders 6 may, as shown in figure 2, extend in a mirror-like manner in relation to each other with respect to a plane extending in the direction of the central axis B of the venturi dryer.

It is apparent to a person skilled in the art that as technology advances, the basic idea of the invention can be implemented in various ways. The invention and its embodiments are therefore not restricted to the above examples, but they may vary within the scope of the claims.