DEVICE AND METHOD FOR SEPARATING LIQUID AND SOLID CONSΗTUENTS OF A FLOW OF MATERIAL
The invention relates to a device according to the preamble of Claim 1. A device of this kind is generally known in the prior art. All kinds of processes produce flows of material which contain liquid and solid constituents. Such flows of material are often flows of waste, but may also comprise other process streams. Moreover, it is often desirable to reduce the level of the liquid constituent in a flow of material of this nature. This can be achieved by heating the flow of material, so that the level of the liquid constituent is reduced by evaporation. If this takes place in a static manner, a considerable amount of heat is required. Another way of separating liquid and solid constituents of a flow of material is to blow heated air tangentially into a conical vessel. The heated air is conveyed further into a process pipe. Moreover, a flow of material is introduced, and the liquid constituent is removed in this way. In the prior art, air or another heated gas may, for example, be generated with the aid of a conventional piston engine.
High levels of power are required, certainly if it is necessary to separate large volumes of material. A drawback of a conventional piston engine is that the mechanical efficiency is high, i.e. the amount of heat dissipated to the outlet gases is low. It is not unusual for conventional piston internal-combustion engines of this nature to have to run warm for a long time before a sufficient flow of hot gas can be drawn off. This means that the process is inflexible and preferably has to be operated continuously.
In this application, the separation of liquid constituents and solid constituents of a flow of material is understood to encompass not only the removal of water, but also the removal of other liquids, such as hydrocarbons .
The object of the present invention is to be able to carry out such separation more efficiently so that it can be widely used and so that all kinds of material flows can be processed. This is because it has been found that if certain flows of material are separated, the product which remains can be utilized to good effect and has an economic value. This applies in particular to flows of waste.
This object is realised with a device described above, by means of the characterizing measures of Claim 1.
In this case, it is possible for the flow of gas or air to move through the inlet vane essentially in the vertical direction, in the horizontal direction, or in any direction lying between the vertical and horizontal. In order to optimize the residence time, according to a preferred embodiment of the invention, it is proposed for the flow of material which is to be treated to be introduced into the flow of gas, which is moving upwards in a turbulent manner, in the vertically upwards direction. It has been found that this results in a very intensive drying. It is assumed that the liquid and solid constituents are separated by the fact that a reduced pressure prevails in the centre of the helical flow of gas and if the flow of material is subjected to a reduced pressure of this nature, the liquid constituents can easily be removed, at least in part, from a flow of material of this nature. By setting the angle of the vanes , the residence time of the flow of material in the flow of heated gas can be controlled. An inlet vane of this nature which is adjustable is used for other applications, such as for centrifugal fans, and can be obtained on the market without great expense .
Using vanes means that, in contrast to structures in accordance with the prior art in which throttling is carried out, for example by means of throttle rings and the like, there is no significant loss of energy and all the kinetic energy is used for moving a flow of material and for separating liquid constituents out of this flow of material. Consequently, the separation can be carried out (much) more effectively. In order to ensure optimum flow, the vanes preferably have a wing-like profile. The mixing of the flow of gas and the flow of material which is to be treated can be optimized further if the vanes are made to vibrate, so that the flow of gas is also made to vibrate.
The invention makes it possible to operate with a comparatively high capacity. As a result, under certain circumstances it becomes possible to atomize the sludge. Atomization makes it easier to remove liquid. The result is new possibilities which were hitherto impossible to realize with the device according to the prior art.
It will be obvious that a further device for separating the now moist gas and the flow of solid material is arranged downstream of the outlet of the device. A separating device of this nature may, for example, comprise a cyclone. The heat which is present in the flow of gas can to a large extent be recovered via a heat exchanger. If the liquid constituents comprise hydrocarbons and other combustible products, the emerging gas can be burnt and, if desired, returned to the circuit. The generation of large volumes of gas for treating a flow of material in the manner described above may be carried out in any way which is known in the prior art. However, it has been found that a particularly high level of efficiency can be achieved using a gas turbine, and more particularly a turbine without a drive shaft. This is because the energy supplied to such a turbine is almost completely converted so as to move gases and/or generate heat. Moreover, a turbine is particularly compact and operationally reliable and, after it is started, almost immediately reaches its operating temperature. Owing to its compact nature, it is possible to arrange the entire device on a moveable frame, so that it can be moved to the location where the flow of waste is situated. It has been found to be possible to transport an installation with an output of greater than 100 kW behind a passenger car in a comparatively small trailer. According to a particularly advantageous embodiment of the invention, the outlet of the line through which the flow of material is introduced is situated in the vicinity of the plane which is defined by the inlet vane.
Owing to the fact that the flow of material is situated essentially in the centre of the outlet of the device, the risk of deposits being formed on the pipe wall or any other part of the discharge is low. The special turbulence which is generated by means of the inlet vane according to the invention means that any deposition will take place in a uniform manner along the wall of the process pipe, in contrast to the wavy pattern formed in the prior art. If deposition should nevertheless occur, a wall of this nature can be cleaned using any wiper which is known in the prior art, thus ensuring that operation is continued.
One possibility is that of arranging a straight bar on the inside of the process pipe, which bar is moved, for example, with the aid of magnetic means which are effective through the wall of the process pipe. This straight bar itself may also comprise magnetic material. However, other scraper means which are known in the prior art are equally possible. For example, it is possible for part of the process pipe to be of double-walled design, in which case the inner wall rotates with respect to the outer wall and the inner wall moves past a scraper or the like which is fixedly connected to the outer wall . Another possible approach is to prevent deposition, for example by means of good insulation or additional heating of the process pipe. It is also possible to periodically reverse the direction of rotation of the turbulent flow of air by suitably adjusting the inlet vane. This makes it possible to remove material. Cleaning of this nature may take place continuously or discontinuously. The invention also relates to a method for separating liquid and solid constituents from a flow of material according to Claim 11.
The invention will be explained in more detail below with reference to an exemplary embodiment which is illustrated in the drawing, in which: Fig. 1 shows a diagrammatic side view of a device according to the invention;
Fig. 2 shows a cross section on line II-II in Fig. 1, and Fig. 3 shows a perspective view, in section, of part of the inlet vane. In Fig. 1, the device according to the invention is denoted overall by 1. It is arranged on a frame 2, further details of which are not shown. A turbine 4 is arranged on this frame. A turbine of this nature may be a turbine which is generally known in the aeronautical engineering sector. It can be started up with the aid of a battery set 20. The outlet of the turbine, i.e. the part from which hot gases are discharged, is connected to a connection line 5. which is in turn coupled to a turbulence chamber 6. It can be seen from Figure 2 that this turbulence chamber can be used to impart a first turbulence to the gas, because the gas is forced to rotate upwards along housing 7 (Fig- 3) • During this movement, the gas meets an inlet vane 8, the opening angle of which can be set with the aid of a control 9. as can be seen from Fig. 3- An outlet or process pipe 10 adjoins housing 7- Inside housing 7 there is a riser 14 which is connected to line 13. which in turn is connected to pump 11 to which a flow of material can be added via funnel 12. The outlet 15 of riser 14 is situated in the plane of the inlet vane 8 and is vertically adjustable. This is important in particular in order to be able to adapt, for example, to the relative density of the sludge which is to be processed.
A cyclone 16 is connected to the process pipe 10. This cyclone, on the one hand, is connected to a receptacle 17 and, on the other hand, is provided with a gas outlet 18 which is passed through a heat exchanger
19.
Straight magnetic bars 21 , 22 may be arranged on both the inside and outside of the process pipe 10 in order to clean the latter. Moving straight bar 21 will cause straight bar 22 to move with it. In this case, it will be obvious that the wall of the process pipe 10 is made from non-magnetic material, such as stainless steel. The device described above operates as follows: After turbine 4, which may, for example be a 175 kW turbine, has been started up, the operating temperature is reached almost immediately. The temperature of the gases moving through connecting line 5 is dependent on the resistance which the gases are subjected to by the setting of the inlet vane. If the angle of the inlet vane 8 with respect to the horizontal is comparatively small, the gas will have a comparatively slow turbulent flow. As a result, the residence time of the gas will be comparatively long and the temperature of the gas will be comparatively high.
Then, or at the same time, a flow of material is supplied via funnel 12. A flow of material of this nature may, for example, comprise a flow of sludge from which moisture is to be removed. However, it is also possible to supply any other flow of material, such as manure, sludges and the like. Sludges are understood to mean process streams which may vary from flows of waste to flows of foodstuffs. The flow of material is moved upwards through the riser and enters housing 7 at outlet 15. The turbulent flow caused by turbulence chamber 6 and inlet vane 8 will be situated essentially along the circumference of housing 7- A reduced pressure will prevail in the centre of housing 7 where outlet 15 opens out, and the flow of material which is sprayed upwards will be subjected to this vacuum. The flow of material is atomized in the process pipe. As a result, separation in the flow of material is accelerated and liquid is entrained, possibly in vapour form, in the flow of gas. Then, the flow of material and the flow of gas will be intimately mixed in the vicinity of the end of the process pipe 10, and then the flow of material and the flow of gas are separated again in cyclone 16. The solid material is collected in the latter, in receptacle or sack 17, while the remaining moist gas is passed through gas discharge 18, where the remaining heat is dissipated via a heat exchanger 19, and this heat can be used in any way, for example for preheating the air which is fed into the turbine or for preheating the flow of material. The gas which leaves the heat exchanger 19 may, if it contains hydrocarbons, be burned or returned to turbine 4 by being condensed.
The adjustable inlet vane described above makes it possible to adjust the residence time in accordance with the type of material which is supplied and the moisture content of this material. In contrast to the situation in the prior art, in the event of prolonged residence time under the same operating conditions of the turbine, there will be an elevated temperature, making the separation more effective. By setting the inclination of the inlet vane so as to generate a flow in the other direction, it is also possible, if appropriate, to remove deposited contaminants.
It has been found that the structure described above makes it possible to carry out particularly efficient drying. Naturally, all this depends on the operating conditions and the content of dry matter in the flow of material supplied. Moreover, the turbine is able to run on many different types of fuels.
Although the above-described design of the invention is a preferred embodiment, it is to be understood that numerous modifications may be added to this design without departing from the scope of this application.