Apparatus for controlling medium flow

An apparatus for controlling medium flow, especially for controlling dilution liquid flow in connection with the headbox of a paper-making machine or a cardboard-manufacturing machine, which apparatus comprises a valve which controls dilution flow, which valve consists of a valve housing, a stem part and a flow channel between an inlet and an outlet of the valve. The stem part is movable in the housing between at least two positions, a first position in which the flow path between the inlet and the outlet is open, and a second position in which the flow path is closed, and the stem part and/or housing is designed to direct the medium flow at least in the vicinity of the outlet opening.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an apparatus for controlling medium flow, especially for controlling dilution liquid flow in connection with the headbox of a paper-making machine or a cardboard-manufacturing machine, which apparatus comprises a valve which controls dilution flow, which valve consists of a valve housing, a stem part and a flow channel between an inlet and an outlet of the valve.

2. Description of Background Art

Dilution valves are utilised for controlling the flow of dilution liquid to stock flow. Dilution flow may be clean or fibre-bearing water. Dilution water may be, for example, tail water taken from the web as retention. Solutions are known in which, a rotatable valve stem is used in the dilution valve which stem may be rotatable to different control positions for controlling the dilution flow starting from the valve. Such solution is presented in, inter alia, specification FI110879B. However, different problems occur in these solutions. Because there is fines included in the tail water, there is a strong possibility of the valve stem getting blocked in the rotatable valve, especially when dilution water reaches between the stem and the valve body. Such solutions require an extremely strong actuator to rotate the stem. In addition, frequent so-called wash moving of the stem is typically required in order to prevent the blocking of the stem. In addition, the solution requires utilising extremely precise tolerances, whereby the solution becomes manufacturing-technically demanding and expensive to manufacture. Typically, the solution requisites utilising an actuator adapted for the use in question, which frequently increases costs. Furthermore, the flow range of the dilution valves in question is fixed. Equivalent problems occur also in a solution presented in specification FI100895B, in which the flow path is formed to the stem which is moved to and fro, and in which the choke is controlled on the side of the valve inlet.

The object of this invention is to achieve a totally novel solution for a dilution valve, whereby the disadvantages of known prior-art are avoided.

BRIEF DESCRIPTION OF THE INVENTION

It is characteristic for the apparatus according to the invention that the stem part is movable in the housing between at least two positions, a first position in which the flow path between the inlet and the outlet is open, and a second position in which the flow path is closed, and that the stem part and/or housing is designed to direct the medium flow at least in the vicinity of the outlet opening.

The solution according to the invention has numerous significant advantages. The dilution valve according to the invention does not get blocked. No great forces are required for moving the valve stem. Common actuators available from several different manufacturers may be easily adapted for the valve actuator. With this solution, contamination and valve leaks are easily avoided. This solution does not require precise tolerances. The flow range may be altered by utilising a replaceable mixing sleeve. The pressure loss accomplished with the design of a mixing zone prevents a so-called flow phenomenon. With the design of the mixing zone parts, it is possible to decrease the forming of flocks and, on the other hand, to break the flocks formed. By replacing the mixing sleeve, it is possible to enlarge or reduce the flow range. By using a to-and-fro linear movement for moving the stem, easy compactability and light, small-force-requiring moving are again achieved. From this results also ease of manufacturing because the structure does not require precise tolerances.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1 and 2present an apparatus according to the invention in cross-section. The apparatus comprises a dilution valve housing, that is, body part1which has an inlet2. The housing, that is, the body part comprises a chamber area11, into which there is a flow path from the inlet2. On the other hand, from the chamber area11is arranged an outlet3. To the housing is arranged movably a stem part4which is movable between at least two positions, a first position in which the flow path to the outlet3is open, and a second position in which the flow path to the outlet3is closed. Typically, between the first and the second position there may be several intermediate positions, whereby the choke of the flow path may be controlled. The stem part is moved with an actuator8(FIG. 3). Depending on the type of the actuator8, the control may be stepless or stepped. The actuator may be any one actuator intended for linear to-and-fro control, such as a pressure-medium-operated piston-cylinder combination or a mechanical motion screw which is operated with an actuator, such as an electric motor.

A stem part4according to an embodiment of the invention is presented in detail inFIG. 4. In the figure, the stem part4comprises a first end42which is towards the outlet (inFIG. 1), and a second end43from which the stem part is fastened to the actuator, for example, through a fastening means. The stem part comprises an abutment surface45for a valve sealing surface72. The stem part has an extending cone surface41which extends towards the first end. Between the extending cone surface41and the first end is first a cylinder surface44, and following that, a tapering cone surface45and a transversal surface47in respect of the longitudinal axis of the stem. Following this, the stem part has a cone-like tip part42. The extending cone part41is typically in the area between the inlet and the outlet of the valve. The cone-like tip part42is typically after the outlet opening3.

To the chamber area11, typically in the vicinity of the outlet3, may be arranged a sleeve member7. The sleeve member7is adapted to function together with the stem part4, typically as its counterpart. The sleeve member7comprises a counter surface71,72for the surface of the stem part. The sleeve member7is a so-called mixing ring with which the flow may be deflected towards the stem part4, especially towards the tip part42of the stem part4. The sleeve member7is advantageously a replaceable part, whereby the characteristics of the valve member, such as flow characteristics, may be adapted depending use. As shownFIGS. 5A and 5B, sleeve member7has an inner surface including: an upper truncated conical portion71that tapers inwardly and downwardly from a top end74of the sleeve member7in a direction toward a lower end73of the sleeve member7, a transverse lip portion72extending inwardly in a radial direction from a lower end of the upper truncated conical portion71, a lower truncated conical portion76that tapers inwardly and downwardly from a inner circumferential edge of the transverse lip portion72, and a cylindrical part77extending downward from a lower edge of the lower truncated conical portion76. When the stem part4is in an open position, a small gap G exists between the abutment surface45of the stem part4and upper truncated conical portion71of the sleeve member. When the stem part4is in the open position, the transverse lip portion72of the sleeve member7deflects the fibre containing medium flow toward the stem part4. When the stem part4is in a closed position, the abutment surface45(the lower truncated conical part) on the outer surface of the stem part4is fitted against the lower truncated conical part76of the sleeve member7. The outer cylindrical surface75of sleeve-member7fits against an inner cylindrical surface of the housing1. (SeeFIGS. 1,2,5A and5B) The sleeve7may be arranged to be fastened to the valve body, together with an outlet pipe6. Specifically, the lower end73of the sleeve member7fits against an upper part of the outlet pipe6.FIG. 6presents a combination of the sleeve member7and the outlet pipe6. The inner surface of the sleeve member7deflects the medium flow towards the stem4, whereby the medium flow impacts most advantageously the tip part42of the stem4which breaks the possible flocks in the flow medium.

Thus, the invention relates to an apparatus for controlling medium flow, especially for controlling dilution liquid flow in connection with the headbox of a paper-making machine or a cardboard-manufacturing machine, which apparatus comprises a valve which controls dilution flow, which valve consists of a valve housing1, a stem part4and a flow channel between an inlet2and an outlet3of the valve. The stem part4is movable in the housing between at least two positions, a first position in which the flow path between the inlet and the outlet is open, and a second position in which the flow path is closed, and the stem part4and/or housing is designed to direct the medium flow at least in the vicinity of the outlet opening.

The stem part4and/or the housing1is designed or arranged to mix the medium flow. To the apparatus is arranged a sleeve member7which constitutes at least a part of an abutment surface to the stem part4. The sleeve member7is arranged to the housing to the outlet opening3or its vicinity. The sleeve member7comprises a surface71,72which deflects the medium flow.

The stem part4comprises in the first end, on the side of the outlet, a tip part42. According to an embodiment of the invention, the stem part4comprises also advantageously an extending part41, which is most advantageously arranged in the stem part to the portion between the valve inlet2and the stem tip part42.

The sleeve member7is replaceable, whereby its design may be adapted according to the target of application. The sleeve member7is arranged to be fastened to the housing1together with the outlet pipe6.

It is obvious to those skilled in the art that the invention is not limited to the embodiments described above, but it may be varied within the scope of the enclosed claims. If required, the characteristic features possibly described in this specification together with other characteristic features may also be used separate from each other.