Abstract:
The invention discloses an improved apparatus for continuous purification of liquids, dewatering and drying of the separated non-filtering solids. The apparatus is intended to be applied for the purification of industrial or household waste liquids, as well water form natural sources, by separating and drying of non-filtering solids. The apparatus can be applied successfully for dewatering and drying of various slurries without the emitting of vapours, dust and other detrimental substances in the atmosphere. The apparatus includes a belt filter ( 1 ) with an incorporated filter sector and an elastic thermos-filter press ( 35 ). The belt filter ensures a continuous purification of water from different sources by separating the non-filtering solids and detrimental ion components comprised in the water, and ensures their bacterial sterility. The separated non-filtering solids are permanently accumulated in the belt filter, and are mixed with the water fed to be purified forming together a slurry. The thickness of the slurry is permanently increasing. After reaching a definite value of thickness, the slurry is pumped by a thickening cone mounted under the filter sector, and is compressed to be dewatered and dried in the elastic thermo-filter press. The cake compressed in the chambers of the elastic thermo-filter press is dewatered and dried in two stages: The first stage is effected by the pressure of a combined vacuum pressure pump, and the vacuum generated by it second vacuum pressure pump. The second stage is realized simultaneously by the longitudinal shrinkage of the elastic thermo-filter press which squeezes the cake, by extraction of the residual capillary moisture under the action of a “steam jacket” generated by the partially evaporated residual liquid phase, and by the vacuum created by the second vacuum pressure pump. The apparatus can be used Successfully for dewatering and drying different types of slurries, and the power consumption is substantially reduced.

Description:
FIELD OF THE INVENTION 
     The invention relates to an apparatus for continuous purification of liquids, dewatering and drying of the separated non-filtering solids. 
     DESCRIPTION OF PRIOR ART 
     No apparatus is known for continuous purification of liquids and dewatering and drying of the separated non-filtering solids in which the non-filtering solids are accumulated in the inflowing liquid to be purified thus forming a mixture (suspension) which is dewatered and dried after reaching a definite density. 
     (The proposed invention consists basically of functionally interconnected belt filter and elastic thermo-filter press, and we will therefore consider the already known similar apparata.) 
     A belt filter is known (U.S. Pat. No. 4,212,745, Yellesma) which comprises a filter belt, moving synchronously upon two conveyor belts, located in sequence one after another. 
     The conveyor belts are sliding on the upper part of two unloading blocks connected to vacuum pumps and outlet pipes effecting the filtration process. 
     A disadvantage of this belt filter is the complicated synchronization required to be maintained during the movement of the filter and conveyor belts. 
     Another disadvantage is that in the described structure no hydrostatic pressure can be exerted on the filter belt, which hydrostatic pressure would speed up the filtration process. 
     A further disadvantage of this belt filter is that only the upper surface of the two unloading blocks is used and thus the capacity of the filtered liquid is reduced significantly. 
     Still another drawback of this belt filter is that the unloading of the dewatered cake is effected by scraping of the filter belt which lead to a rapid wear of the filter cloth, reduces its operating life and impairs the filtration process. 
     A belt filter acting by subpressure—vacuum (EP 0391091 A1, Teckentrup, Heinrich) is known, comprising a container of a definite volume, where the suspension to be filtered flows in. A closed chamber connected to the vacuum pump is located on the bottom of the container. There are apertures at the upper portion of the chamber. A drain belt lies over these apertures, and over the drain belt there is a continuous filter belt. The filtered liquid is carried out by vacuum from the closed chamber, and the residual cake on the filter belt is separated by means of a rotating brush ands is disposed of through an appropriate hole. 
     A disadvantage of the belt filter with subpressure is that only the upper surface of the closed chamber is employed for filtration and therefore the filtering capacity is diminished considerably. 
     A further drawback of the belt filter with subpressure is that not more than one chamber can be used with it. This leads to a manifold reduction of the amount of filtered liquid and the capacity of the belt filter. 
     Another disadvantage of the belt filter with subpressure is that it cannot act as a thickener. The filter belt carries the wet cake out and ensures a continuous process. This is unquestionably useful, but the process is accompanied by the following unfavourable technological results: 
     The wet cake sticking to the filter cloth can be separated with difficulty; 
     The separation of the cake from the filter cloth is not complete and a layer of fine solids remains which impairs its filtering capacity; 
     The mechanical separation of the wet cake reduces the filter cloth&#39;s operation life; 
     The produced wet cake cannot be fed further for additional filtration in a filter press where the mode of dewatering is better and a lower final humidity can be achieved. 
     The obtained wet cake can practically only be dried in an appropriate drier which would cause high costs for heating energy and contamination of the environment by dust and hazardous vapours. 
     A filter press (U.S. Pat. No. 3,608,610, Greatorex) is known, in which dewatering is carried out in two stages: 
     The first stage is completed by traditional compression of a given suspension in the chambers of a filter press, and the liquid phase is filtered through the filter belt whereafter cake with a high content of residual liquid phase remains in the chambers. 
     In the second stage additional dewatering of the cake is achieved, and special elastic hydraulic membranes mounted in the cells of the filter press swell, whereby the volume of the chambers is reduced and thus the residual liquid phase in the cake is driven through the filter belt. 
     A disadvantage of the filter press is that the elastic membranes are situated opposite to the filter belt and are therefore limiting each filter chamber by an area equal to its filtering area. The residual amount of liquid in the cake driven out by the hydraulic swelling of the membrane is equal to the inflowing amount of hydraulic liquid. 
     Another disadvantage of the filter press is the expensive and difficult realization of a structural connection between the elastic hydraulic membranes and the supporting surface they are lying upon, because the hydraulic liquid is fed under pressure between the elastic hydraulic membranes and the supporting surface of each filter chamber. 
     A further disadvantage of the filter press is that no full drying of the cake to the extent of a final dry product can be achieved in it without the need for its additional transportation and drying with the help of appropriate drying equipment. 
     A method and filter press for dewatering of suspensions and drying of the filtered cake is known (U.S. Pat. No. 4,999,118, and U.S. Pat. No. 5,143,609, B. Beltchev). 
     The basic element in this apparatus is a filter press with heating and filtering plates. Dewatering and drying in the filter press is effected in two stages: 
     The first stage is completed after the traditional compressing of a given suspension in the chambers of the filter press, whereas the liquid phase is filtered through the filter plates and cake with a high content of liquid phase remains in the chambers. 
     The second stage begins by providing power supply to the heating membranes embodied in the heating plates. 
     The higher temperature of the heating membranes evaporates part of the residual liquid phase in the cake and a “steam jacket” is formed around the heating membranes. Under the impact of the steam pressure, the “steam jacket” drives the residual liquid phase from the capillaries of the cake and in mixture of vapours and liquid thus obtained is drawn under vacuum by means of the filtration plates. The effect generated by the “steam jacket” ensures a considerable lowering of the consumption of heat energy as compared with the known drying apparatuses. 
     A disadvantage of the method and apparatus for dewatering of suspensions and drying of the filtered cake is that during the second stage the residual liquid in the cake&#39;s capillaries is driven out only under the action of the “steam jacket” without providing for additional compression and thickening of the cake in the chambers of the filter press. 
     Another drawback of the method and apparatus for dewatering of suspensions and drying of the non-filtering cake is that the filter press cannot be effectively used in the process of thickening. 
     SUMMARY OF THE INVENTION 
     The aim of the invention is to create an apparatus for continuous purification of liquids and dewatering and drying of the separated non-filtering solids (cake), whereas the liquid to be purified is continuously flowing into the apparatus and the purified liquid is continuously flowing out from it, and the separated non-filtering solids are accumulated in the apparatus and are mixed with the inflowing liquid to be purified and develop a suspension of constantly increasing thickness to reach a predetermined value. 
     Another objective of the invention is to ensure a rapid dewatering and drying of the suspension which has reached the predetermined value with a minimum power consumption and a minimum industrial floor area. 
     The task has been solved with an apparatus comprising functionally interconnected belt filter and elastic thermo-filter press. The belt filter consists of feed container, filter sector and thickening cone. The filter sector is located under the feed container, and the thickening cone is linked with its upper portion to the filter sector. The lower part of the thickening cone is connected by means of a fixed unloading pipe, a pipe, a combined vacuum pressure pump and supply pipe to the elastic thermo-filter press. The filter sector is linked by means of an outlet vacuum pipe, a vacuum collector and a main vacuum pipe to a main vacuum pump. At its other side, the filter sector is connected by means of a reducing pipe, a pressure pipe, a second combined vacuum pressure pump, a second vacuum collector and a thermo-fluid detector to the elastic thermo-filter press. 
     The filter sector comprises a robust frame. In the robust frame are located: a perforated absorption chamber, an elastic box and a perforated drive drum. To the perforated absorption chamber are embodied a gas-impermeable sheathing and a porous chamber partition, whereas a basket filled with absorbent substance is located in the perforated absorption chamber. A sealed cover is fixed to the perforated absorption chamber. A vacuum chamber is shaped by the porous chamber partition and the gas impermeable sheathing. The vacuum chamber is connected to the main vacuum pump through the outlet pipe, the vacuum collector and the main vacuum pipe. 
     A continuous drain belt is laid through spacer rollers upon the perforated absorption chamber and the gas impermeable sheathing. A belt screen located over the gas impermeable sheathing is connected to the one side of the elastic box, and the perforated drive drum is located at the opposite side of the elastic box. 
     A second motor reduction gear is connected with the perforated drive drum. The perforated drive drum is connected with a fixed hollow shaft by means of second sealed bearings. The perforated drive drum is connected with the robust frame by sealed bearings. A fixed screen with a horizontal screen slit is mounted concentrically in the interior of the perforated drive drum. The fixed hollow shaft is connected in sequence at its one side through the reduction pipe, the pressure pipe, the second combined vacuum pressure pump, the second vacuum collector and the thermo-fluid detector to the elastic thermo-filter press. The fixed hollow shaft is blind at its second end. 
     The elastic box comprises a frame, a hard sliding arch and two semi-free sliding arches, mounted one upon another and suspended elastically at their opposite sides to the elastic box. A jack is mounted between the frame and the semi-free sliding arches, whereas a supporting segment is located under the semi-free sliding arches and is connected to the upper part of the jack. 
     The continuous filter belt encompasses in succession the continuous drain belt, the belt screen, the elastic box and the perforated drive drum. Magnetic fibres are interwoven in the continuous filter belt. Rollers, second rollers and cleaners are mounted upon the external surface of the continuous filter belt. A magnetic detector is fixed in the robust frame. 
     A control panel is connected with the combined vacuum pressure pump, the second combined vacuum pressure pump, the jack, the magnetic detector, the second motor reduction gear and density detector mounted inside the thickening cone. 
     The elastic thermo-filter press consists of elastic filter plates, arranged in succession between heating plates following each other. Elastic hollow conduits are laid on both sides of the internal frames of the elastic filter plates. Heating membranes with feed holes are mounted in the heating plates. 
     A self-propelled head is connected by drive nuts to guide screws located at the one end of robust stems. The robust stems are connected at their other end with pistons. The pistons are laid in hydraulic cylinders, and the hydraulic cylinders are fixed to a fixed head. Hydraulic pipes connect the hydraulic cylinders to a hydraulic pump. The fixed head is connected through fixed couplings with supporting beams. 
     The self-propelled head, the elastic filter plates and the heating plates are suspended through supporting rolls on the supporting beams. The self-propelled head, the elastic filter plates, the heating plates and the fixed head are interlinked by means of pivots. The elastic filter plates and interconnected by flexible pipes. The elastic filter plates, are connected to a fluid pump through the flexible pipes. The elastic filter plates are connected in their lower part to the second combined vacuum pressure pump through flexible vacuum pipes, the thermo-fluid detector and the second vacuum collector. 
     The elastic filter plate comprises an internal frame, and a vacuum channel is located in the lower part of the internal frame. The vacuum channel is connected at its external end to the flexible vacuum pipes, and the internal end of the vacuum channel is connected with a vacuum filter chamber of the elastic filter plate. The vacuum filter chamber is limited by the internal frame and two porous partitions. A feed pipe inlet is located in the vacuum filter chamber and in the porous partitions. The feed pipe inlet is connected to the combined vacuum pressure pump by a supply pipe. A fluid channel is located in the internal frame. The fluid channel is connected in its external end with the flexible pipes, and the internal end of the fluid channel is connected with the elastic hollow conduits. The internal frame is embraced by an elastic frame, and the elastic hollow conduits are formed between the internal frame and the elastic frame. The elastic hollow conduits are located on the two parallel and vertical sides of the internal frame. 
     The control panel is connected with the motor reduction gear, the heating membranes, the fluid pump, the hydraulic pump, the thermo-fluid detector and a control valve. 
     An advantage of the invention is that filtration is effected continuously under the action of the hydrostatic pressure of the inflowing liquid to be purified and the vacuum generated in the vacuum chamber. Thus the continuous removal of the non-filtering solids and their mixing with the inflowing liquid to be purified takes place in the belt filter itself. The obtained suspension with an ever increasing density can be pumped out at a definite value of thickness, i.e. a thickness that is technologically most advantageous for the filtering and drying process. 
     Another advantage of the invention is that the continuous filter belt operates completely submerged in the filter sector, and during the filtration process the accumulation on its surface of a thickened layer of non-filtering solids is eliminated. Thus the micropores of the continuous filter belt do not clog, and the cleaning of the perforated drive drum is facilitated. This ensures a stable filtration process and a longer operating life of the continuous filter belt. 
     A further advantage of the invention is that the effective area of filtration of the continuous filter belt is practically the predominant part of its whole area. 
     Following the well known hydraulic compression of the suspension, the accumulated cake is subjected to additional mechanical compression, accomplished as a result of the longitudinal shrinking of the elastic thermo-filter press. At this stage the residual capillary liquid is driven out by both the shrinking and the steam of the “steam jacket” generated around the heating membranes. Thus and exceptionally rapid dewatering and drying process is achieved with a very small consumption of energy. 
     Another advantage of the invention is that the rapid processes of filtration, thickening, dewatering and drying lead to a manifold reduction of both the dimensions of the apparatus and its operational floor space. 
     An advantage of the invention is as well its capacity to separate simultaneously the hazardous ion components and to provide for bacterial sterilization of water originating from natural or other sources. 
     With these and other objects in view which will become apparent in the following detailed description, the present invention which is shown only by example, will be clearly understood in connection with the accompanying drawings, in which: 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG.  1 . General view of the functionally interconnected belt filter and elastic thermo-filter press. 
     FIG. 2 General view of the belt filter. 
     FIG. 3 Diagram of the vertical cross-section of the filter sector. 
     FIG. 4 Diagram of the horizontal cross-section of the filter sector. 
     FIG. 5 Diagram of the transverse cross-section of the continuous drain belt. 
     FIG.  6 . View of the internal side of the continuous drain belt. 
     FIG.  7 . Diagram of the transverse cross-section of the elastic thermo-filter press after closing the elastic thermo-filter press by the self-propelled head. 
     FIG. 8 Diagram of the transverse cross-section of the elastic thermo-filter press after longitudinal shrinkage of the elastic thermo-filter press by the action of the hydraulic cylinders. 
     FIG. 9 Diagram of the elastic filter plates. 
     FIG.  10 . Vertical cross-section of the elastic filter plates. 
     FIG.  11 . General view of the elastic thermo-filter press in open position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The apparatus for continuous purification of liquids, dewatering and drying of the separated non-filtering solids includes a belt filter  1  and an elastic thermo-filter press  35 . 
     The belt filter  1  (FIGS. 1 and 2) consists of a feed container  2 , filter sector  3  and thickening cone  9 . 
     The filter sector  3  (FIGS. 1-4) is located under the feed container  2 , and the thickening cone  9  is connected in its upper portion to filter sector  3 . The bottom part of the thickening cone  9  (FIG. 1) is connected by a fixing unloading pipe  10 , pipe  11 , a combined vacuum-pressure pump  12  and a feed pipe  67 , to the elastic thermo-filter press  35 . 
     The filter sector  3  (FIGS. 1-4) is connected by an outlet vacuum pipe  18 , a vacuum collector  19  and a main vacuum pipe  60  to a main vacuum pump  59 . The filter sector  3  is connected at its other side by a reducing pipe  28 , a pressure pipe  107 , a second combined vacuum-pressure pump  104 , a second vacuum collector  72  and a thermo-fluid detector  50  to the elastic thermo-filter press  35 . 
     The filter sector  3  (FIGS. 1-4) consists of a robust frame  4  which houses a perforated absorption chamber  5 , an elastic box  88  and a perforated drive drum  22 . To the perforated absorption chamber  5  are mounted a gas inpenetrable sheathing  14  and a porous chamber partition  13 . A basket  15  filled with absorbent  16  is located in the perforated absorption chamber  5 . A sealed cover  17  is connected to the perforated absorption chamber  5 . 
     A vacuum chamber  6  (FIGS. 3 and 4) is shaped by the porous chamber partition  13  and the gas inpenetrable sheathing  14 . The vacuum chamber  6  is connected through the outlet vacuum pipe  18 , the vacuum collector  19  and the main vacuum pipe  60  to the main vacuum pump  59 . 
     A continuous drain belt  7  (FIGS.  3 ÷ 6 ) is laid on spacing rollers  34  upon the perforated absorption chamber  5  and the gas inpenetrable sheathing  14 . 
     A belt screen  21  (FIGS. 3 and 4) is located above the gas inpenetrable sheathing  14 , and is linked to the one side of the elastic box  88 . The perforated drive drum  22  is located at the opposite side of the elastic box  88 . 
     The perforated drive drum  22  (FIGS. 3 and 4) is connected to a second motor reducing gear  80 . The perforated drive drum  22  is linked to the fixed hollow shaft  27  through second sealed bearings  102 , and through sealed bearings  30  the perforated drive drum  22  is linked to the robust frame  4 . 
     A fixed screen  24  (FIGS. 3 and 4) with a horizontal screen slit  25  is mounted concentrically into the interior of the perforated drive drum  22 . The fixed hollow shaft  27  is linked in sequence by its one side through the reducing pipe  28 , the pressure pipe  107 , the second combined vacuum pressure pump  104 , the second vacuum collector  72  and the thermo-fluid detector  50  to the elastic thermo-filter press  35 . The fixed hollow shaft  27  is blind in its second end and is fixed by a second fixed connection  101  to the robust frame  4 . 
     The elastic box  88  (FIGS. 3 and 4) consists of a frame  90 , a solid sliding arch  89  and two semi-free sliding arches  91  mounted one upon the other and suspended elastically by their opposite sides to the elastic box  88 . A jack  94  is mounted between the frame  90  and under the semi-free sliding arches  91 . A supporting component  93  is mounted under the semi-free sliding arches  91 , and the supporting component  93  is linked to the upper part of the jack  94 . 
     The continuous filter belt  8  (FIGS. 3,  4 ) embraces in succession the continuous drain belt  7 , the belt screen  21 , the elastic box  88  and the perforated drive drum  22 . Magnetic filaments  97  are interwoven in the continuous filter belt  8 . Rollers  79  second rollers  92  and cleaners  23  are located upon the external surface of the continuous filter belt  8 . A magnetic detector  98  is fixed to the robust frame  4 . 
     A control panel  56  (FIGS. 1 and 7) is connected to the combined vacuum pressure pump  12 , to the second combined vacuum pressure pump  104 , to the jack  94 , to the magnetic detector  98 , to the second motor reducing gear  80 , to the air filter  112  which is connected to the second vacuum collector  72  and to a density detector  95 ,mounted in the thickening cone  9 . 
     The elastic thermo-filter press  35  (FIGS. 1,  7 ,  8 ,  11 ) consists of elastic filter plates  40 ,aligned in sequence between heating plates  38  following each one after another. Elastic hollow conduits  75  are laid on both sides of internal frames  39  of the elastic filter plates  40 . Heating membranes  73  with feed inlets  113   a  are mounted into the heating plates  38 . A self-propelled head  36  is couples by guide nuts  66  to guide screws  70  located at the one end of robust stems  46  and at their other end the robust stems  48  are connected to pistons  116 , lying in hydraulic cylinders  45 . The hydraulic cylinders  45  are fixed to fixed head  37  and hydraulic pipes  68  are linking the hydraulic cylinders  45  to a hydraulic pump  43 . The fixed head  37  is connected by fixed couplings  87  to supporting beams  85 . The self-propelled head  36 , the elastic filter plates  40 , the thermo plates  38  and the fixed head  37  are interconnected by pivots  44 . The elastic filter plates  40  are interconnected by flexible pipes  42 . The flexible pipes  42  are connected to fluid pump  47 . The elastic filter plates  40  are interconnected at their lower parts by flexible vacuum pipes  78 . The flexible vacuum pipes are connected through the thermo-fluid detector  50 , the second vacuum collector  72  to the second combined vacuum pressure pump  104 . 
     The elastic filter plate  40  (FIGS. 1,  7 ,  8 ,  9 ,  11 ,) comprises an internal frame  39  and in the lower part of the internal frame  39  is located a vacuum duct  110 . The vacuum duct  110  is connected in its external end to flexible vacuum pipes  78  and in its internal end it is connected to vacuum filter chamber  64  of the filter plate  40 . The vacuum filter chamber  64  is limited by the internal frame  39  and two parallel porous partitions  74 . A tube feed inlet  113  is located in the vacuum filter chamber  64  and in the porous partitions  74 . The tube feed inlet  13  is connected to the combined vacuum pressure pump  12  by a feed pipe  67 . 
     A fluid canal  76  is located in the internal flame  39 . The fluid canal  76  is connected at its external end with flexible pipes  42 , and the internal end of the fluid canal  76  is connected to the elastic hollow conduits  75 . The internal frame  39  is embrace by elastic frame  41 . 
     The elastic hollow conduits  75  are formed between the internal frame  39  and the elastic frame  41 . Chambers with variable volume  117  are formed by the flexible filter plates  40 , the heating plates  39  and the hollow conduits  75 . The elastic hollow conduits  75  are located at the two parallel and vertical sides of the internal frame  39 . The control panel  56  is connected to a motor reduction gear  65 , to the heating membranes  73 , to the fluid pump  47 , to the hydraulic pump  43 , to the thermo-fluid detector  50  and to a control valve  53 . 
     MANNER OF OPERATION 
     The apparatus of the invention operates as follows: 
     The liquid to be purified  62  comprising basically industrial and household waste liquids, or water from natural water sources, is permanently fed into a feed container  2  of a belt filter  1  whilst the liquid is maintained at a constant level. 
     By action of hydrostatic pressure and vacuum, the liquid to be purified  62  is filtered through a continuous filter belt  8  and through a continuous drain belt  7  flows in a perforated absorption chamber  5 . 
     In the perforated absorption chamber  5  a basket  15  is located, filled by absorbing substance  16 , selectively catching any detrimental ion components. 
     The liquid to be purified  62 , after passing through the continuous filter belt  8 , the continuous drain belt  7  and the absorbing substance  16 , flows out as purified liquid  61 . 
     Then, by the action of hydrostatic pressure and vacuum from a main vacuum pump  59 , the purified liquid  61  is passed through a porous chamber partition  13  into a vacuum chamber  6  and through an outlet vacuum pipe  18  is then fed into a vacuum collector  19 . 
     An ozonizer  57  with ozonizing nozzle  20  is mounted to the outlet vacuum pipe  18  and ensures additional bacterial sterility. Thus the purified liquid  61  is accumulated in the lower portion of a vacuum collector  19  and is regularly removed through the purified liquid valve  58 . 
     Vacuum in the vacuum collector  19  is maintained by the main vacuum pump  59  through a main vacuum pipe  60 . 
     When the absorbing substance  16  becomes saturated with detrimental ion components, a sealed cover  17  opens, and the absorbing substance  16  is replaced by a fresh portion. 
     The continuous filter belt  8  is driven by a perforated drive drum  22 . 
     The continuous filter belt  8  is sliding upon the surfaces of a solid sliding arch  89  and half-free sliding arches  91  forming together a flexible box  88 , and upon the surface of a belt screen  21 . The continuous filter belt  8  drives a continuous drain belt  7  adhering tightly to its surface. 
     The continuous drain belt  7  is rotated upon the perforated absorption chamber  5  and a gas impenetrable sheathing  14  by means of spacer rolls  34 , mounted under the lamellae  31  of the continuous drain belt  7 . 
     The filtered liquid is drained through canals  32  of laminae  31  and flows out through spacer joints of the lamellae  31  formed by pivot connections  33 , and the filtered liquid flows into the perforated absorption chamber  5 . 
     Non-filtering solids  103  stick to the outer surface of the continuous filter belt  8  only at its portion where the continuous filter belt  8  gets into contact with the surface of the continuous drain belt  7 . 
     Cleaners  23  are permanently separating the non-filtering solids  103  from the surface of the continuous filter belt  8  at the line where the continuous filter belt  8  is detached from the continuous drain belt  7 , and at the line where the continuous filter belt  8  gets into contact with the surface of the perforated drive drum  22 . 
     In filter sector  3 , rollers  79  and secondary rollers  92  press the continuous filter belt  7  to the belt screen  21  and to the flexible box  88 . 
     To the filter sector  3 , horizontal supporting components  100  are mounted which are fixed to a robust frame  4  and support the perforated absorption chamber  5 , the vacuum chamber  6 , and the flexible box  88 , thus ensuring their stability in the process of operation. 
     The half-free sliding arches  91  of the flexible box  88  are permanently straining the continuous filter belt  8  by means of a supporting segment  93 , which supporting segment  93  is pressing the half-free sliding arches  91  by the action of a jack  94 , mounted on a frame  90  of the flexible box  88  and the bottom part of the flexible box  88  is a solid arch  89 . 
     A hydraulic jack connection  115  is linked to a control panel  56  and maintains the necessary tension of the continuous filter belt  8 . 
     Magnetic fibres  97  are interwoven in the continuous filter belt  8  and are signaling to a magnetic detector  98  any changes of speed. 
     Thus, through a signal circuit  99  of the magnetic detector  98 , the control panel  56  controls the speed of the continuous filter belt  8  and regulates it through the hydraulic jack connection  115  by eliminating the sliding (friction) between the continuous filter belt  8  and the perforated drive drum  22 . 
     The perforated drive drum  22  is rotated by a second motor reductor gear  80  through a second chain  111 . 
     The perforated drive drum  22  is linked through its internal side to a fixed hollow shaft  27  by secondary sealed bearings  102 , and through its external side it is connected to the robust frame  4  by sealed bearings  30 . 
     The second motor reductor gear  80  is power supplied and controlled by a cable line  114  of the control panel  56 . 
     In the middle of the fixed hollow shaft  27  a nozzle  29  is located. 
     Through the nozzle  29 , filtrate  71  or aerosol  26  are fed under pressure. 
     One end of the fixed hollow shaft  27  is blind and is fixed by means of a second fixed coupling  101  to the robust frame  4 . 
     A fixed screen  24  screens the inside of the perforated drive drum  22  and is attached to the fixed hollow shaft  27 . 
     A horizontal screen slit  25  of the fixed screen  24  gives shape to a wide and thin pressure jet of the filtrate  71  or the aerosol  26 , cleaning the micropores of the continuous filter belt  8  from the non-filtering solids  103 . 
     Thus the filtering capacity of the continuous filter belt  8  is practically preserved for a long period of operation. 
     It is clear from the aforesaid that the liquid to be filtered  62  is permanently fed into the feed container  2  of belt filter  1 , and the purified liquid  61  is permanently separated from vacuum chamber  6 . 
     The non-filtering solids  103  collected upon the continuous filter belt  8  are mixed with the fed liquid to be purified  62  and the mixture (slurry) thus obtained is continuously thickened. 
     The increasing thickness is permanently controlled by a density detector  95  connected through a second signal line  96  to the control panel  56 . 
     When the desired density is reached, an elastic thermo-filter press  35  is included in the dewatering and drying process of the thickened mixture (slurry) in the belt filter  1  only when the control panel  56  activates a fluid pump  47  through a first operating line  48 . 
     Through flexible pipes  42  and fluid ducts  76  the fluid pump  47  compresses fluid into elastic hollow conduits  75  formed by elastic frames  41  and internal frames  39  of elastic filter plates  40 . 
     The elastic hollow conduits  75  are located on the two parallel sides of the internal frame  39 , Robust rims  69  embrace the external portions of the elastic filter plates  40 . 
     The flexible hollow conduits  75  expand to a predetermined size under the impact of fluid pump  47 . 
     When the predetermined size and pressure are reached, the control panel  56  stops the fluid pump  47  and activates, through a third operating line  83  a motor reductor gear  65 , and by means of chain  108  and drive nuts  66  moves a self-propelled head  36  along guide screws  70  formed at the one end of robust stems  46 . 
     The motor-reductor gear  65  is switched off automatically whenever the self-propelled head  36  closes the elastic thermo-filter press  35 . 
     The expanded hollow conduits  75  ensure a tight and reliable contact between the flexible filter plates  40  and heating plates  38 . 
     The expanded hollow conduits  75  predetermine the desired thickness of the cake  63  accumulated in the chambers with variable volume  117 . 
     Whenever the elastic thermo-filter press  35  is closed, the control panel  56  activates a combined vacuum and pressure pump  12  through a fourth operating line  84 . 
     The combined vacuum and pressure pump  12  draws out the thickened mixture (slurry) from the bottom of a thickening cone  9  through a fixing unloading pipe  10  and a pipe  11 . 
     The thickened mixture (slurry) is then compressed through a feed pipe  67  and a tube feed inlet  113  into the chambers limited by the elastic filter plates  40  and the heating plates  38 . 
     The filtrate  71  is separated by porous partitions  74  under the pressure produced by the combined vacuum and pressure pump  12  and the vacuum developed in vacuum filter chambers  64  by a second combined vacuum pressure pump  104  linked through a fifth operating line  105  to the control panel  56 . 
     From the vacuum filter chambers  64 , the filtrate  71  flows through vacuum ducts  110 , vacuum flexible pipes  78  and a thermo-fluid detector  50  into a second vacuum collector  72 . 
     The filtrate  71  can be regularly let out by a filtrate valve  54 . 
     The filtrate  71  can also be pumped out by the second combined vacuum pressure pump  104  through a second feed pipe  106  and through a pressure pipe  107 , a reducing pipe  28 , the fixed hollow shaft  27 , and the nozzle  29 , to be fed into the perforated drive drum  22 . 
     The filtration process is controlled by the thermo-fluid detector  50 , and through a thermo-fluid detector connection  82  the filtration processed is recorded by the control panel  56 . 
     After the completion of the filtration process, the control panel  56  activates a hydraulic pump  43  through a second operating line  49 . 
     The hydraulic pump  43  activates hydraulic cylinders  45  through hydraulic pipes  68 . 
     The activation of the hydraulic pump  43  makes the control panel  56  set into operation heating membranes  73  of the heating plates  38  through a power supply cable  51 . 
     Around the surface of the heating membranes  73  a process of evaporation of the residual liquid phase begins, leading to the formation of a “steam jacket”. 
     Simultaneously with the activation of the hydraulic pump  43 , the control panel  56  starts the switched-off the fluid pump  47  through the first operating line  48 , and at this stage the fluid pump  47  lowers the pressure in the flexible pipes  42  which results in a gradual shrinking of the elastic hollow conduits  75 . 
     The hydraulic cylinders  45  mounted on a fixed head  37  pull out, under the effect of the pressure of the hydraulic pump  43 , pistons  116  of the hydraulic cylinders  45 . The pistons  116  are connected to the second ends of the robust stems  46 . 
     Thus the distance between the self-propelled head  36  and the fixed head  37  is decreased, i.e. the elastic thermo-filter press  35  contracts longitudinally. 
     As a result of the contraction under the effect of the hydraulic cylinders  45 , the volume of the cake  63  accumulated in the chambers with variable volume  117  begins to compress and shrink. 
     Thus the second stage of dewatering begins, accompanied by partial evaporation. 
     During the second stage, the residual liquid phase in the capillaries of the cake  63  is filtered through the porous partitions  74  into the vacuum-filter chambers  64  under the simultaneous effect of: 
     the vapours of the “steam jacket” formed on the surface of the heating membranes  73  which push out the capillary liquid phase; 
     the mechanical pressing and squeezing of the cake  63  under the impact of the hydraulic cylinders  45 ; and 
     the vacuum developed by the second combined vacuum pressure pump  104 . 
     The residual liquid phase entering by filtration into the vacuum filter chambers  64 , is practically the aerosol  26  comprising: liquid, steam and air. 
     The aerosol  26  flows further through the thermo-filter detector  50 , the second vacuum collector  72 , the second feed pipe  106 , the second combined vacuum and pressure pump  104 , the pressure pipe  107 , the reducing pipe  28 , the fixed hollow shaft  27 , the nozzle  29 , the horizontal screen slit  25 ; and through the perforated drive drum  22  the aerosol  26  cleans the micropores of the continuous fitter belt  8  and then the aerosol  26  is mixed with the liquid fed to be purified  62  in the belt filter  1 . 
     Thus, the thermal energy accumulated in the aerosol  26 , imparted by the heating membranes  73  of the heating plates  38 , is conveyed with negligible losses to the liquid fed to be purified  62 . 
     The second stage of dewatering is completed with the end of aerosol separation, i.e. the cake  63  is dewatered and dried to a maximum. 
     Separation of the aerosol  26  is controlled by the thermo-fluid detector  50 , and the signal obtained is fed to the control panel  56  through the thermo-fluid detector connection  82 . 
     At the end of the second stage, the control panel  56  issues a signal for: 
     the switching off of the hydraulic pump  43 ; 
     the switching off of power supply cable  51  to the heating membranes  73 ; 
     the switching on of the self-propelled head  36 , which opens the elastic thermo-filter press  35 , and thus increases the distance between the elastic filter plates  40  and the heating plates  38  interconnected by pivots  44 ; 
     the switching on of vibrating stems  109  located in the supporting columns  86 . 
     The vibrations of the vibrating stems  109  are imparted through supporting beams  85  and the supporting rolls  77 , to the elastic filter plates  40  and the heating plates  38  suspended on the supporting beams  85 . 
     In result of the effect of vibrations, the dewatered and dried cake  63  is disconnected from the heating plates  38  and the elastic filter plates  40 , and falls into an appropriate hopper. 
     The fixed head  37  is connected by a fixed coupling  87  to the supporting beams  85 . 
     A manometer  81  indicates the pressure in the chambers of the elastic thermo-filter press  35 . 
     The thickening cone  9  can be cleaned regularly by removing a thickening cover  55 . 
     The belt filter  1  can be equipped with two or more filter sectors  3 . 
     After the discharge of the cake  63 , the elastic thermo-filter press  35  is ready for the next working cycle. The start of the next working cycle is determined by the moment when the density of the resulting mixture of non-filtering solids  103  and the liquid to be purified  62  flowing into the belt filter  1 , reaches a predetermined value. 
     The time interval from the end of one cycle until the beginning of the following cycle varies within a wide scope depending on the characteristics and volume of the liquid to be purified  62 . 
     When the elastic thermo-filter press  35  is engaged and operates only with the belt filter  1 , its production capacity may remain to a great extent unused. 
     In such cases, it is economically efficient to link one elastic thermo-filter press  35  with two or more belt filters  1  in the process of operation, or to build in two or more filter sectors  3  in one belt filter  1 . 
     The belt filter  1  and the elastic thermo-filter press  35  can function separately as two apparatuses independent from each other. 
     When the belt filter  1  operates independently, a control valve  53  connected to the control panel  56  through a control line  52  switches off the thermo-fluid detector  50  and switches the air filter  112 . 
     In this case, the second combined vacuum and pressure pump  104 ; compresses air into the perforated drive drum  22 , and this air cleans the micro pores of the continuous filter belt  8 . 
     The thickened mixture of non-filtering solids  103  and the inflowing liquid to be purified  62  is brought out by the thickening cone  9  by the action of the combined vacuum and pressure pump  12  after reaching the predetermined value of density (thickening). 
     The elastic thermo-filter press  35  can operate independently by being supplied from various sources with mixtures of liquids containing dispersed solids (slurry mass). 
     The supply to the elastic thermo-filter press  35  is performed by the combined vacuum and pressure pump  12 . 
     The control valve  53  disconnects the air filter  112 . 
     The filtrate  71 , by the action of the second combined vacuum and pressure pump  104 , is collected through the thermo-filter detector  50  into the second vacuum collector  72 . 
     Although the invention is described and illustrated with reference to a plurality of embodiments therefore, it is to be expressly understood that it is in no way limited to the disclosure of such preferred embodiments, but is capable of numerous modifications within the scope of the appended claims.