Homogenizing valve

Abstract

Homogenizing valve, comprising a housing (1) having a fluid inlet (2) and a spatially separate fluid outlet (3) in which a valve body is arranged, characterized in that the valve body consists of a sleeve (4) connected to the fluid outlet (3), which has at least one radially open and closed gap (6) extending helically in the wall (5), with a gap height (h) that can be varied, wherein a pressure element (7) acting axially on the sleeve (4) is provided to change the gap height (h).

Description

[0001] The invention relates to a homogenizing valve according to the preamble of claim 1.

[0002] Homogenizing valves of this type are used, for example, in emulsifying and mixing processes, particularly with multiphase fluids at high flow rates. In these processes, emulsions and dispersions are pressurized by a high-pressure pump to a process-dependent pressure, typically in the range of approximately 50 to 500 bar, and forced through narrow gaps.

[0003] During the resulting relaxation, the desired comminution of the dispersed phase is achieved due to turbulence and shear. The aim is to achieve the smallest possible particle size with a narrow particle size distribution and the lowest possible energy input.

[0004] Homogenizing valves generally consist of a mostly ring-shaped valve seat that has a bore in the center and, together with a cylindrical valve, forms a valve gap through which the process fluid is forced.

[0005] The gap height depends on the flow rate of the process fluids and should be kept as small as possible to achieve the desired properties. Therefore, for larger flow rates, so-called multi-gap valves are used, in which the total flow is divided in parallel across individual gaps formed by several valve discs. EP 0 034 675 B1 specifies optimal gap heights of 30–50 µm, particularly with regard to minimizing energy consumption.

[0006] If the fluids are aerosols whose solid components are of varying sizes, the homogenization principle is achieved through a sieving or separation process. This process involves conveying the fluid at a lower pressure (approximately 2–10 bar) through sieve elements with short, straight or curved openings and a small, fixed gap height. This shifts the size distribution of the solid particles towards smaller average particle sizes or reduces the solid content overall.

[0007] Multi-gap valves are used in the pharmaceutical and cosmetics industries, among others, and especially in the food industry, for example in the processing of dairy products or fruit juices, as well as in fiber processing.

[0008] Multi-gap valves used for this purpose are disclosed, among others, in US 5,749,650 A, WO 01 / 003 818 A1, WO 01 / 003 819 A1, and WO 2012 / 084 986 A1. In these designs, several annular valve discs are stacked and configured such that a gap forms between two overlapping valve discs. Spring elements allow the gaps to be opened to enable pressureless cleaning in the ready-to-use position.

[0009] In operation, the fluid flows from the fluid inlet centrally into the valve discs and radially through the gaps, splitting into radially flowing individual volume flows. These are then deflected and recombined, and the pressure is reduced to a return pressure by a second valve.

[0010] However, the known valves and filter elements have significant disadvantages both in terms of their design and their operation.

[0011] The large number of components required leads to significant manufacturing costs as well as increased susceptibility to malfunctions, which in turn results in operational interruptions.

[0012] Disadvantages also arise from tolerances of guide surfaces that affect product quality, possible inequality of gap heights, susceptibility to vibration, increased cleaning effort due to contact surfaces and gaps, high spare parts requirements, assembly and maintenance effort, general susceptibility to errors, and increased effort in procurement and storage due to the variety of parts.

[0013] For example, the valve discs must each be made of a hard, wear-resistant, rust-free material, which involves high costs for material procurement and processing.

[0014] High costs also result from the fact that spring elements are provided for centering the valve discs, for example in the valve known from US 5,749,650 A. This requires a correspondingly large radial installation space, which leads to an overall valve size that contradicts the requirements for a dimensionally optimized shape.

[0015] Furthermore, the installation space required for the springs restricts the cleaning capability of the valve, which is a major disadvantage for use in, for example, the food industry, where so-called CIP cleaning (CIP = Cleaning In Place) without disassembling the components is required.

[0016] The respective gap with a predetermined depth between the valve discs can only be achieved with a correspondingly large amount of grinding effort during the manufacturing of the valve discs.

[0017] Furthermore, adjusting conventionally designed valves presents problems when matching the gap height to the flow rate at a given homogenization pressure. The gap height is determined by a fixed distance, achieved through grinding, between the bearing surfaces and the valve surface through which the flow passes.

[0018] The required total area of ​​the gaps through which the fluid flows is predetermined for a given process pressure. Therefore, with an integer number of discs, adjustments are usually necessary to achieve the exact pressure. This is done by deforming the upper discs using excess actuating force. This problem is particularly pronounced when variable, especially significantly different, flow rates occur during operation. As a result, the gap heights are no longer constant, but can be smaller or even completely closed in the upper area due to deflection.

[0019] Since the gap height affects product quality, it is no longer constant for each gap, which can negatively impact the homogeneous distribution overall, thus contradicting the purpose of the process and the quality requirement.

[0020] Regardless, the operational reliability of this valve is not guaranteed, as the large pressurized surfaces of the valve discs require high actuating forces. This results in a significant force surplus when process-related disturbances occur, such as air bubbles in the fluid flow or its brief interruption, for example, during switching operations. This force surplus leads to high bending stress, particularly on the valve discs facing the fluid inlet, which can cause them to break.

[0021] In state-of-the-art valves, the actuating forces are predominantly generated by force control, i.e., hydraulically, in order to apply the required high forces. The necessary energy source is usually not part of the valve installation, so a separate power unit must be installed and operated, which also entails increased investment and operating costs.

[0022] In conventional aerosol processing, the sieve elements are subject to the risk of clogging due to the fiber elements becoming stuck, as the gaps are fixed, rigid and cannot be opened.

[0023] The invention is based on the objective of further developing a homogenizing valve of the generic type in such a way that it is structurally simpler in design, more cost-effective to manufacture, and its functional reliability is improved.

[0024] This problem is solved by a homogenizing valve having the features of claim 1.

[0025] Compared to the state of the art, the new homogenizing valve can be operated with significantly fewer functional parts, whereas the aforementioned multi-gap valves provide a large number of individual independent, parallel flowing gaps, for example formed by the top and bottom of individual valve discs.

[0026] According to the invention, however, only a sleeve is inserted into the interior of a housing with at least one open gap in the wall of the sleeve. The gap runs helically, preferably with a consistent pitch. As has been shown, the desired degree of homogenization is already achieved when only one gap of sufficient length is provided.

[0027] A pressure element acting on the sleeve deforms the sleeve in the axial direction in such a way that the gap height changes, i.e., decreases, to a predetermined extent, thereby generating or changing the homogenizing pressure.

[0028] For cleaning the homogenizing valve in particular, the gap height should be reset to allow optimal flow of the cleaning fluid. For this purpose, the pressure element can be disengaged, allowing the initial height to be restored by the restoring forces of the sleeve. However, it is also conceivable that the pressure element, which is then rigidly connected to the sleeve, is designed in such a way that a tensile force is exerted, thereby increasing the gap height to its initial height, with both end sections of the gap tapering to a point with a gap height of 20–50 µm.

[0029] The very simple design of the new homogenizing valve offers significant advantages over the state of the art. These advantages include, in particular, reduced manufacturing costs and lower susceptibility to malfunctions, as well as increased operational reliability, leading to a substantial reduction in operating costs.

[0030] Furthermore, the reduction of relevant disturbances and influencing factors results in an increase in the product quality of the finished homogenized fluid. Product quality is now essentially determined by a single component, in contrast to the prior art with its numerous components, their manufacturing tolerances, and mutually negative interactions. These interactions particularly affect product quality because, due to the aforementioned tolerances, the quality-determining gaps have different heights, resulting in an uneven homogenization effect, such as an excessively wide, coarse, or bimodal particle size distribution.

[0031] The slot can be created in the sleeve using various methods. For example, machining by milling, water abrasive blasting, or laser or electron beam cutting. The latter also leads to a hardening of the surface of the slot's edge areas, which increases wear resistance.

[0032] The sleeve preferably consists of rust-free, martensitic stainless steel alloys, nickel- or cobalt-based alloys, or nickel-bonded hard metal.

[0033] The new homogenizing valve can generally be operated in either flow direction through the sleeve while retaining the aforementioned advantages, both from the inside out and from the outside in. This is particularly advantageous due to the possibility of backflushing when processing process fluids containing particles or fibers.

[0034] The latter, preferable option offers the advantage that the valve body is under compressive stress, which is particularly beneficial in terms of strength when using hard materials with high wear resistance but low ductility, such as cemented carbide. Furthermore, this design requires only low actuating forces to close the valve. A flow direction from the inside out can be preferably chosen for pressureless backflushing during cleaning.

[0035] Another advantage arises from the possibility of continuously measuring and monitoring the gap height during operation, so that information about the wear condition, the expected maintenance and consequently the product quality can be obtained.

[0036] Depending on the requirements, the cross-sectional geometry of the gap can be selected. A cross-sectional contour with parallel gap walls, meaning a radially constant gap height, is conceivable. The cross-sectional contour can be conical with gap walls tapering in the flow direction, or a combination of a conical gap in the inlet area followed by parallel gap walls. This design variant has proven advantageous when processing aerosols containing solids. The total radial length of the gap, i.e., the wall thickness of the sleeve, is approximately 2–6 mm, depending on the pressure and the selected gap geometry.

[0037] As has been shown, the gap height in the effective area at the narrowest point during homogenization is preferably 30-50 µm. In contrast, during almost pressureless cleaning operation, it is approximately 1-3 mm.

[0038] Further advantageous embodiments are described in the dependent claims.

[0039] Exemplary embodiments of the invention are described below with reference to the accompanying drawings.

[0040] They show: Fig. 1 and Fig. 2 each a schematic representation of a homogenizing valve according to the invention in a cutaway side view, Fig. Three different design variants of a detail of the homogenizing valve are also shown in a schematic cutaway side view.

[0041] In the Fig. 1 and Fig. Figure 2 shows a homogenizing valve, with a housing 1 having a fluid inlet 2 and a fluid outlet 3.

[0042] According to the invention, a valve body in the form of a sleeve 4 is arranged in the housing 1, in the wall 5 of which a helically extending gap 6 is provided, open towards the interior of the sleeve 4 and with a gap height h that can be varied. Both ends of the gap 6 are closed.

[0043] To change the gap height h, a pressure element 7 is located on the end face of the sleeve 4 opposite the fluid outlet 3, while the sleeve 4 is supported on the opposite side at the base of the housing 1.

[0044] In the Fig. Figure 1 shows an operating position of the homogenizing valve in which a fluid can be homogenized. The gap height h ( Fig. 3) of the column 6 is reduced compared to the initial height by compression using the pressure element 7.

[0045] The fluid to be homogenized is forced under pressure through the fluid inlet 2, located in a side wall of the housing 1, across the interior of the housing 1, which forms a pressure chamber, and through the gap 6 of the sleeve 4. The homogenized fluid is then discharged through the fluid outlet 3 provided in the bottom of the housing 1, which is open towards the interior of the sleeve 4.

[0046] The in er Fig. The position of the homogenizing valve shown in Figure 2 results from cleaning the interior of the housing 1 and the sleeve 4. The pressure element 7 is essentially inactive, i.e., without pressure, so that the sleeve 4 returns to its initial position, in which the gap 6 assumes its initial height.

[0047] In the Fig. Figure 3 shows examples of different cross-sectional configurations of the gap 6. An enlarged section of the wall 5 of the sleeve 4 is shown in the cross-sectional view.

[0048] The Fig. 3a) shows the slit 6 with parallel interfaces 8, while after the Fig. 3b) the gap 6 narrows in the direction of fluid flow, as indicated by an arrow D. Finally, the Fig. 3c) a cross-sectional contour again, according to which the gap 6 from a conical inlet to the interior of the sleeve 4 transitions into a contour with parallel interfaces 8, corresponding to the Fig. 3a) passes. Reference symbol list 1 case 2 Fluid inlet 3 Fluid outlet 4 Sleeve 5 Wall 6 columns 7 Pressure element 8 Boundary area h gap heights E Inflow direction A Outflow direction F Direction of force

Claims

[1] Homogenizing valve, comprising a housing (1) having a fluid inlet (2) and a spatially separate fluid outlet (3) in which a valve body is arranged, characterized by , that the valve body consists of a sleeve (4) connected to the fluid outlet (3), which has at least one radially open and closed gap (6) in the wall (5) which is helically extending in its gap height (h) and is radially open and closed at both ends, wherein a pressure element (7) acting axially on the sleeve (4) is provided to change the gap height (h). [2] Homogenizing valve according to claim 1, characterized by , that the pressure element (7) rests against an end face of the sleeve (4), closing it. [3] Homogenizing valve according to claim 1 or 2, characterized by , that the fluid outlet (3) is assigned to the end face of the sleeve (4) opposite the pressure element (7), which is supported on the bottom of the housing (1). [4] Homogenizing valve according to any of the preceding claims, characterized by , that the fluid inlet (2) opens into the interior of the housing (1) outside the sleeve (4). [5] Homogenizing valve according to any of the preceding claims, characterized by , that the gap (6), with the exception of the preferably tapered end regions, is formed with a consistently uniform gap height (h). [6] Homogenizing valve according to any of the preceding claims, characterized by , that the gap height (h) can be reduced to an initial height when the sleeve (4) is depressurized. [7] Homogenizing valve according to any of the preceding claims, characterized by , that the gap height (h) is radially equal. [8] Homogenizing valve according to any one of the preceding claims 1 to 6, characterized by , that the gap (6) is designed to taper in the direction of fluid flow [9] Homogenizing valve according to any one of the preceding claims 1 to 6, characterized by, that the gap (6) initially tapers in the direction of fluid flow and transitions into a region with the same gap height (h).

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