Print sheet filter unit.

Description

2 The blade filter plates are typically provided at the bottom and in the middle with an outlet opening connected to an inlet opening of a common collector for the discharge of the filtrate. 5 In the rest of the document we will refer to the liquid with solid particles to be purified as suspension, the filtered liquid as the filtrate, and the separated solid particles as the residue. 10 The tank of a pressure blade filter unit has a typical cylindrical shape and can be positioned horizontally or vertically. The present invention is intended for vertically positioned pressure blade filter units. This means that the longitudinal axis of the cylindrical tank extends mainly parallel to the direction of gravity. In such vertically positioned pressure blade filter units, the width of the blade filter plates is not uniform due to the cylindrical shape of the tank. Indeed, the leaf filter plates near the central longitudinal axis of the tank are widest. The width of these leaf filter plates subsequently decreases towards the tank jacket.The blade filter plates must therefore fit within the curved wall of the cylindrical tank. The reasons for this are therefore primarily geometric in nature. BE2024 / 5906 3 As you move further towards the jacket or inner wall of the tank, the circumference increases due to the cylindrical shape. This means that blade filter plates cannot all be of equal width, but rather a varying width is required of the blade filter plates to both efficiently utilize the internal space in the tank and retain the functional benefits of good flow and easy maintenance. The known pressure blade filter units have the disadvantage that internal pressure differences are present during operation, which causes a very uneven flow in the collector and through the various blade filter plates. As a result of the warping of the blade filter plates and uneven or poor filter cake buildup, this occurs on the filter elements, making unwanted stops of the filtration unit inevitable. The current invention aims to offer a solution to the aforementioned and 20 other disadvantages.This concerns the invention of a pressure sheet filter unit, comprising the following elements: -a cylindrical tank with a jacket, a bottom and a lid, where the tank is intended for vertical arrangement such that the longitudinal axis of the tank is parallel or quasi-parallel to the direction of gravity; -an inlet opening in the tank for the supply of suspension; BE2024 / 5906 4 -an outlet opening in the tank for the discharge of filtrate; -an outlet in the tank for the discharge of residue; -at least two sheet filter plates provided with a predominantly rectangular frame, with a height and width b, in which a plate-shaped filter element is installed, whereby at least two sheet filter plates have a different width, whereby each sheet filter plate is installed vertically in the internal volume of the tank, one and the other such that the height of each sheet filter plate is parallel or quasi-parallel to the longitudinal axis of the cylindrical tanks and whereby each sheet filter plate is provided with an outflow opening; -a collector provided with inflow openings that 15are connected to the corresponding outlet openings of the blade filter plates for the discharge of filtrate, a characteristic that the outlet openings of at least two blade filter plates have a different diameter.20 Because the diameter of the outlet openings of the blade filter plates within the same pressure blade filter unit is no longer uniform, the diameter of the outlet openings can be matched to the size of the filtration surface of the filter elements. In this way, the diameter of the outlet openings is matched to the flow rate of the blade filter plates.30 BE2024 / 5906 5 This offers the advantage that internal pressure differences between the different blade filter plates are avoided, which ensures a very uniform flow in the collectors through the different blade filter plates. 5 An additional effect of this is that warping of the leaf filter plates and uneven or poor filter cake buildup on the filter elements are prevented, whereby unwanted stops of the filtration unit can be avoided to the maximum extent.10The diameter of the outflow openings of the sheet filter plates shall therefore preferentially be directly proportional to the width of the sheet filter plates or proportional to the size of the surface area of ​​the filter element of the sheet filter plates. The diameter of the outflow openings and the diameter of the corresponding inflow openings preferably decrease from the central longitudinal axis of the cylindrical tank towards the jacket. In other words, the sheet filter plates with the greatest width or with the greatest surface area of ​​the filter element (greatest filtration surface) are provided, according to invention, with the largest diameter of the outflow opening. This means that the flow rates and also the filtration efficiency of each individual sheet filter plate are optimized, whereby the flow rates and filtration efficiency of the total sheet filter unit also increase significantly. Because the total flow rate of the pressure sheet filter unit according to the invention is much greater than the total flow rate of the known pressure sheetFor filter units of the same size, the inner diameter of the collector of the pressure sheet filter unit according to the invention is preferably approximately 75% larger than the inner diameter of the collector of the known pressure sheet filter units of the same size. Theoretically, a pressure sheet filter unit according to the invention can offer an efficiency improvement and a production gain of more than 300% compared with the known pressure sheet filter units. With the aim of better demonstrating the characteristics of the invention, some preferred designs of a pressure sheet filter unit according to the invention are described below as examples without any restrictive character, with reference to the accompanying drawings, in which: Figure 1 schematically and in perspective depicts a pressure sheet filter according to the invention; Figure 2 depicts a top view according to arrow F2 in Figure 1, with the sheet filter plates removed. BE2024 / 5906 7 The pressure sheet filter unit shown in Figure 1 comprises a mainly cylindrical tank 2 with a jacket 3, a bottom 4 and a lid 5.The cylindrical tank 2 is positioned vertically, whereby it is clear that the central longitudinal axis of the tank 2 is parallel to the direction of gravity. For reasons of clarity, a part of the casing 3 has been cut away such that the internal volume of the tank 2 is partially visible. The tank 2 is equipped with an inlet opening 6 for the supply of the suspension to be filtered, an outlet opening 7 for filtrate, and an outlet 8 for the discharge of residue or solid particles. In this example, the outlet 8 is closed by an electrically operated butterfly valve 9. In the internal volume of the tank 2, a number of leaf filter plates 10 are positioned vertically or, in this case, suspended. Each sheet filter plate10 consists mainly of a 25 rectangular frame11 with a height and a widthb in which a plate-shaped filter element12 is fitted or tensioned. The filter element12 is, for example, a filter cloth or filter mesh, manufactured from, for example, five layers.30 BE2024 / 5906 8 The frame11 is provided all around the perimeter edges of the filter element12 with a discharge channel that leads to aoutflow opening13 leads. Vertically positioned or suspended leaf filter plates105 means that the heighth of the leaf filter plates10 runs parallel to the direction of gravity or runs parallel to the central longitudinal axis of the cylindrical tank2. 10 The aforementioned outflow opening13 is located at the bottom, near the center of each leaf filter plate10, for the discharge of filtrate. The outflow opening13 of each leaf filter plate10 is15 connected to a corresponding inflow opening14 of a common collector15 which collects, gathers and discharges the filtrate from each leaf filter plate10. The diametersd of the outflow openings13 and20 corresponding diametersD of the inflow opening14 are matched to each other in such a way that a liquid-tight fit is created. In this case, the connection between the two is established by means of a seal. 25 From Figure 1 it is clear that the widthb of the leaf filter plates 10 varies. The leaf filter plates 10 with the largest widthb are located close to thecentral longitudinal of the tank2, or in other words in the vicinity of the center or middle of the tank30 2. The sheet filter plates10 with the smallest widthb BE2024 / 5906 9 are located closest to the jacket or inner wall of the tank2. Characteristic of the invention is that the diameterd of the outflow openings13 of the various sheet filter plates5 10 is not uniform across the entire series of installed sheet filter plates10 in the tank2. In the variant shown, the sheet filter plates10 with the largest width have the largest diameterd of the10 outflow openings13. The same applies, of course, to the diameterD of the inflow openings14 of the collector15. Since the diameter and the diameterD as mentioned above15 must be matched to each other to achieve a liquid-tight fit. In this example, the sheet filter plates 10 are located in the vicinity of the central longitudinal shaft of the tank 2, thus the 20 largest outflow diameter, and the sheet filter plates 10 that are furthest removed from the aforementioned have the smallest diameter. Since the filtration surface of the sheet filter plates 1025where the central longitudinal axis of tank 2 is largest, the filtration surface and the liquid flow rate are also greatest there. Consequently, it is a logical choice to provide the largest diameter of the outflow opening 13 there.30 BE2024 / 5906 10 In the example shown, eleven blade filter plates 10 are displayed, six of which have different diameters. This is better seen in Figure 2, where a top view of the internal volume of tank 2 is shown, with the lid open 5 and with the blade filter plates removed 10, arranged in such a way that the collector 15 and the different diameters of the inflow openings 14 are more clearly visible.10 The inflow openings of the collector 15 are located on a single straight line in this example. Indeed, the diameter D of the inlet openings is smallest in the vicinity of the jacket of tank 2 and increases towards the center of tank 2. Since the leaf filter plate has the greatest width in the center and thus also the largest filtration surface area, the diameter D of the inlet opening is largest there.The diameters D of the outlet openings13 and inlet openings14, respectively, are directly proportional25 to the width b of the blade filter plates10 or directly proportional to the size of the filtration surface of the filter elements12. Although not shown in the figures, collector 15 could also be placed outside the internal volume of tank 2 BE2024 / 5906 11. Collector 15 can then, for example, be placed under the bottom 4 of tank 2, with a pipe installed between each outlet opening 13 and inlet opening 14, each extending through the bottom 4 of tank 2. If collector 15 has more inlet openings 14 than if sheet filter plates 10 are installed in tank 2, the inlet openings 14 that are not coupled with a sheet filter plate 10 can be fitted with a plug. The diameter of this plug is naturally always matched to the diameter D of the inlet opening 14 so that a liquid-tight fit is created. It is clear to the professional that when reference is made 15 to the diameters d of the outlet openings 13 anddiametersDoftheinflow openings14 that the inner diameters of the outflow openings13, respectively inflow openings14 are meant. 20 Parallel or quasi-parallel means that there is a maximum deviation of ten degrees between the direction of gravity and the central longitudinal axis of the tank 2. 25 The present invention is by no means limited to the example described and