APPARATUS FOR DRAINING OF SLUDGE

Abstract: An apparatus for draining sludge is assembled from a filter press with a ring-shaped press chamber (2) coupled with a piston pump (14) which feeds sludge from a reservoir to a forechamber (13) communicating with the press chamber (2). A reciprocating press piston (5) in the press chamber (2) is advanced for squeezing the sludge and on retraction opens a passage from the forechamber (13) to the press chamber (2). The piston pump (14) is coupled with the press piston (5, 11) in such a way that the pump (14) feeds sludge to the forechamber (13) at each retraction of the press piston (5). The press chamber (2) is surrounded by cylindrical filter walls (3, 4) and closed at the top of the press by means of a removable lid (6) which can be removed by parallel displacement in the direction of the central axis of the press chamber by means of an opening/closing mechanism. A drain (10) for liquid is led to the bottom of the chamber (8) in the inner filter cylinder (3). The press piston (5) is moved by a hydraulic mechanism.

Description: APPARATUS FOR DRAINING OF SLUDGE The present invention relates to an apparatus for draining sludge, in particular for use on a mud exhauster vehicle which is used for emptying septic tanks but which also may be used stationary in connection with small water purifica¬ tion plants and the like. As generally known septic tanks serve as fermentation tanks where solids from household sewage water are retained and partially precipitated such that the sewage water dischar¬ ged from the septic tanke is purified to a certain extent. The accumulated sludge must be removed from the septic tank at regular intervals, for example once a year, and disposed of in a satisfactory way, for example by deposition on a certified waste dump or combustion in a refuse combustion plant. The dry matter content in the sludge in a septic tank is typically between 1% and 3%, and it is in principle only this dry matter which must be removed from the tank. Thus the predominant part by far of the sludge which is trans- * ported to the waste dump or refuse combustion plant, is wa¬ ter which it would not be necessary per se to remove from the septic tank. This means that in the cleaning of septic tanks there is transported a very large volume of water al¬ though basically there is no necessity for this. It would be desirable to be able to remove most of the water from the sludge and return the water to the septic tank in order to save transportation expenses. In fact it is rather difficult, due to the low dry matter content, to drain water from the sludge from septic tanks. The dry matter consists mainly of fibrous materials with a large pore volume, and most commonly the sludge has the consistency of a thin paste. In the draining systems as known today there is therefore added a flocculating agent (lime) such that the dry matter flocculates and precipi¬ tates to a certain degree whereafter the water is drained off from the precipitate in a succeeding treatment step. Seen in relation to this known technique it is the purpose of the invention to provide an apparatuε for draining sludge which works entirely mechanically, that is, without the addition of consumables such as flocculating agents, and which is particularly suited for use on a mud exhauster vehicle but which also may be used at small water purifica¬ tion plants and the like. According to the invention as set forth in patent claim 1 this purpose iε attained with an apparatus which is charac¬ terized in that a filter press with a ring-shaped press chamber in the apparatus has a ring-shaped press piston which may be advanced within the press chamber for squee¬ zing the sludge and thereafter retracted again, that the sludge is fed to the filter presε from a forechamber, the preεs piston during its retraction opening a passage from the forechamber to the press chamber and during its advan¬ cement closing the pasεage again, that the apparatuε is provided with a piston pump coupled to feed sludge from a reservoir to the forechamber, and that the piston of the pump is coupled to the preεs piston in such a way that the pump feeds sludge to the forechamber during each retraction of the preεε piston. According to the invention a filter presε with a ring- shaped preεε chamber iε used for the draining of the sludge. Such a filter preεε iε in principle known from Da- niεh patent no. 37726, but in thiε known filter preεε the material to be pressed is to be urged down into the presε chamber by means of a rotating arm; therefor one must as¬ sume that it will be unusable for draining sludge from εep- tic tanks as the latter flows too lightly. Yet in accor¬ dance with the invention it has been found that a filter press with a ring-shaped presε room can be used for drai¬ ning sludge when it iε provided with a ring-shaped press piston. In this instance the sludge cannot escape from the pressure and because of the ring shape of the presε chamber the water must only travel a short way in order to leave the sludge. The sludge feeding must be adapted to the stro¬ king work cycle of such a filter press, however, and it is shown to be advantageous in this instance to feed the sludge from a . reservoir to a forechamber by means of a pi¬ ston pump whose piston is coupled to the piston of the press piston. The coupling is such that the pump operates during the return stroke of the preεs piston so that the capacity of the driving mechanism is exploited in an advan¬ tageous way. The feeding of εludge to the preεε chamber iε controlled by the presε piston itself as the latter opens and cloεes a pasεage from the forechamber to the press chamber. Preferred embodiments of the invention are set forth in the εubclaimε. Through the constructive embodiment as recited in claim 2 the pasεage from the forechamber to the preεε chamber at- tainε a large εectional area εuch that the filling happenε relatively quickly, thus in turn allowing a speedy work cycle of the the apparatus. The draining of the waεte water through a drain from the bottom of the room within the inner filter cylinder, the drain at the same time serving as a guide for the press pi¬ ston, according to claim 3, has shown to contribute consi¬ derably to the mechanically safe functioning of the appara- tus. By providing the press with a removable lid as in claim 4 the problem of evacuating the drained filter cake is " solved in a constructionally simple way. The mechanism for taking off the lid and removing the drai¬ ned filter cake may preferably be built as in claim 5, aε particularly the lid must be scraped completely clean so that it may be fitted tightly on the filter presε again af¬ ter the evacuation of the filter cake. A preferred exemplary embodiment of an apparatus for the draining of sludge according to the invention will be de¬ scribed in the following with reference to the accompanying drawing, which is a simplified εectional view of the appa- ratuε. In the drawing there is seen a filter presε 1 with a cy¬ lindrical ring-shaped presε chamber 2 which is delimited by an inner filter cylinder 3 and an outer filter cylinder 4. A ring-εhaped preεs piston 5 may be moved up and down in the presε chamber 2 by a hydraulic mover mechaniεm (not εhown) which co priεeε two hydraulic cylinders that are connected to the piston 5. The preεε piεton 5 presses the material present in the press chamber against an upper lid 6 which iε retained against the pressure by a hydraulic me¬ chanism (hydraulic cylinder) 7. The liquid preεεed out of the material in the preεs chamber traverseε the filter cy- linderε 3 and 4 and enterε an inner drain chamber 8 and an outer drain chamber 9, reεpectively. From the bottom of the inner drain chamber 8 there a drain 10 iε led downward, the drain 10 at the same time serving as a guide for an inward¬ ly extending bottom collar 11 on the ring-εhaped preεε pi¬ εton 5. The εecure guiding of the press piston 5 thus at¬ tained eases the tightening of the various tight-fitting surfaces. The inner filter cylinder 3 is longer than the outer filte cylinder 4. The lower part of the inner filter cylinder therefore protrudes from the outer filter cylinder and is surrounded by a forechamber 13 which receives sludge from piston pump 14. The piston pump 14 consists of a pump chamber 15 with an inlet 16 and an outlet 17, the inlet and outlet being pro¬ vided with check valves 18. A pump piston 19 which can be moved up and down in the pump chamber 15 is coupled to the press piston 5. The details of the coupling are not shown but merely indicated schematically. Aε iε apparent from the orientation of the check valveε, aε shown in the drawing, sludge is fed into the pump chamber 15 via the inlet 16 while the piston 19 is moved upward, and there iε preεεed εludge out of the pump chamber 15 and up into the fore¬ chamber 13 when the piston 19 iε moved downward. When the apparatus shown in the drawing iε operating, the preεε piεton is moved up and down in the ring-shaped inter¬ space 2, the stroke path of the piston being measured such that it moves substantially down to the bottom of the fore¬ chamber 13. Thereby there is above the piston opened a pas¬ sage from the forechamber to the ring-εhaped interεpace 2 between the filter cylinderε, and sludge iε fed into thiε interspace by the piston pump 14. Subsequently the piston 5 is moved upward in the ring-shaped interspace 2 whereby the water iε pressed out of the εludge, enterε the chamberε 8 and 9 through the filter cylinderε and leaves the chambers through the drains 10 and 20. Because it is moved by hydraulic cylinders the press piston 5 has a variable stroke length. This is important for the functioning of the press because after one or more strokes of the press piεton 5 there will build up a filter cake of drained εludge having an increasing height. Thuε εludge from a plurality of strokes is accumulated in the press chamber. The drained filter cake exerts a certain counter- pressure against the action of the piston, and the advance¬ ment of the piston within the preεε chamber 2 stopε by it- self when thiε counterpreεsure corresponds to the pressure in the hydraulic system which drives the presε piston 5. It is this variability of the stroke length which ultimately enables an accumulation of εludge from a plurality of stro¬ kes in the presε chamber; thiε contributes to a conεider- able degree to an economic and effective operation because emptying has to be done correspondingly lesε often. The drained filter cake in the preεs chamber 2 is evacuated by the hydraulic mechanism 7 lifting the lid 6 at the top of the pump so high that the lid paεseε a ring-εhaped scra¬ per 21. The filter cake iε pressed out of the ring-shaped interspace 2 by eanε of the piεton 5 and is guided to an accumulator funnel 23 on the side of the piεton preεs I by meanε of the scraper 21 which is moved by a hydraulic e- chaniεm 22. From there the drained εludge iε fed further out of the apparatus for storage via a conveyor duct 24 which may be equipped with a screw conveyor or the like. After the evacuation of the filter cake the scraper 21 is moved back to its original place whereafter the lid 6 iε placed on the filter press 1 and the presεing proceεε con¬ tinueε. It haε turned out that with thiε apparatus the dry matter content in the εludge may be increased from a value between typically 1% and 3% to a value between typically 15% and 25%. Thus a conεiderable reduction iε attained of the vol¬ ume and the weight which must be tranεported from the place where the εludge iε collected to the place of diεpoεal. In the embodiment shown the filter cylinders 3 and 4 are made as cylinders of woven metal supported by vertical bars which in turn are held by means of rings 25. The rings are only εhown for the inner filter cylinder 3, however. Con¬ structional details such as seals, connections etc. are no included in the drawing, to further the illustrativeneεs. The apparatus shown is particularly suitable for integra¬ tion with mud exhauεter vehicleε but may also be used εta- tionarily for example in εmall water purification plants.

Claims: P tent cla ms 1. Apparatus for draining sludge, in particular for use on a mud exhauεter vehicle, with a filter preεs having a ring- shaped preεε chamber, c h a r a c t e r i z e d in that the filter press has a ring-shaped preεε piεton (5) which may be advanced within the preεs chamber (2) for squeezing the sludge and thereaf¬ ter retracted again, that the sludge iε fed to the filter preεε (1) from a forechamber (13), the preεε piεton (5) du¬ ring itε retraction opening a paεεage from the forechamber to the preεs chamber and during itε advancement cloεing the paεεage again, that the apparatuε is provided with a piston pump (14) coupled to feed sludge from a reservoir to the forechamber, and that the piston (19) of the pump iε coupled to the preεε piεton (5, 11) in such a way that the pump (14) feeds sludge to the forechamber (13) during each retraction of the preεε piεton (5). 2. Apparatuε according to claim 1, c h a r a c t e r i z e d in that the preεε chamber (2) iε delimited axially by a lid (6) placed opposite the presε piεton (5) and radially by an inner (3) and an outer filter cylinder (4), each in the form of a liquid-permeable, cy- lindrical wall, of which the outer (4) iε shorter than the inner (3), that the forechamber (13) iε εubεtantially ring- εhaped and surroundε the inner filter cylinder (3) where the latter protrudeε from the outer filter cylinder (4), and that during each εtroke the preεε piεton (5) iε pulled back so far within the forechamber (13) that thereby a ring-εhaped paεεage iε opened from the forechamber to the press chamber (2). 3. Apparatus according to claim 2, c h a r a c t e r i z e d in that the lid (6) is at the top of the filter presε, at that from below there is led a drain (10) for liquid to the bottom of the room (8) within the inner filter cylinder (3), which drain serves as a guide for a radially inward extending bottom collar (11) on the press piston (5, 11) 4. Apparatus according to one of the preceding claims, c h a r a c t e r i z e d in that the lid (6) is mounted removably so that drained sludge may me evacuated from the presε chamber (2) through an opening created by removal of the lid. 5. Apparatus according to claim 4, c h a r a c t e r i z e d in that the filter preεε (1) is provided with an opening/cloεure mechaniεm (7) for the lid adapted to diεplace the latter in parallel with the direc¬ tion of the central axis of the filter cylinderε, and pro¬ vided with a scraper mechanism (21, 22) adapted to remove evacuated drained sludge from the removed lid (6) in a di¬ rection transverse to the central axis. 6. Apparatus according to one of the preceding claims, c h a r a c t e r i z e d in that the preεs piεton (5) iε moved by a hydraulic mechaniεm εuch that the εtroke length of the preεε piεton during advancement is variably determined by the relation between the hydraulic pressure and the pressure in the drained sludge within the presε chamber (2) .

Inventors: GERDING JENS ERIK, GERDING, JENS, ERIK
Applicants: OPTIMAL MILJOETEKNIK APS
Application year: 1988
Main classification: C02F11
IPC codes: B01D29, B30B9