The invention relates to a method of cleaning a shut off valve from coatings after use, where the shut off valve goes through a number of cleaning steps when mounted.

Such a process is known as CIP which stands for Cleaning in Place, as the shut off valve remains in mounted condition during the cleaning process. This type of cleaning processes typically entails that the valve, in its open condition, is rinsed with a cleaning agent.

WO2016091204A1 shows a valve which is adapted to CIP-cleaning by means of a spray ball that is mounted in front of a butterfly valve. According to the invention, a number of cleaning steps are performed, said cleaning steps comprising rinsing with a rinsing agent, heating with hot steam and drying under low pressure, where at least rinsing with rinsing agent is performed with the shut off valve in a closed position. According to the invention, a centre tube which conducts material to or away from the shut off valve, is moved in its axial direction towards or away from a tube flange that surrounds the shut off valve, said centre tube, in a first service situation, is moved forward to seal around the whole circumference thereof against the surrounding tube flange, and, in a second service situation intended for cleaning of the shut off valve, is moved in its axial direction back in the direction away from the surrounding tube flange, whereby an alternative flow channel perpendicular to the longitudinal axis of the centre tube is opened, said shut off valve in the first service situation is: i. either open and allows material to pass through the shut off valve and through the centre tube, or ii. closed and closes for material transport through the shut off valve and hence also closes the centre tube, said shut off valve in the second service situation is: iii. either open and allows material transport through the centre tube and through the alternative flow channel and through the shut off valve, or

iv. closed so that there is only transport through the centre tube past the shut off valve and through the alternative flow channel. In this way it is ensured that the closing surface of especially the shut off valve is cleaned properly, while the cleaning liquid, at the same time, does not pass through the shut off valve and into a process plant.

When the shut off valve, in the second service situation intended for cleaning, is moved in its axial direction away from the tube flange, an alternative flow channel is established, which is perpendicular to the longitudinal axis of the centre tube, so that the cleaning liquid can come into good contact with the shut off valve, especially when said valve is shut. But the alternative flow channel can also, when it is open, be used for discharge of cleaning liquid that for instance is directed through the now open shut off valve. By the method it is ensured, via the alternative flow channel, that not only the surface of the shut off valve that faces the centre tube, but all parts thereof including sealing surfaces are cleaned effectively, and discharge of cleaning liquid can take place safely through the alternative flow channel.

According to claim 2 it is preferred that the centre tube is moved in its axial direction by means of establishing a pressure difference between the two sides of an annular piston which is coupled axially to the centre tube, said annular piston externally seals against a cylinder that is held fast against the surrounding tube flange. In this way, a secure and precise control of the position of the centre tube so that closing and opening of the alternative flow channel always can be controlled. Furthermore, the alternative flow channel can be shut completely as the centre tube is pushed against a seat sealing in the surrounding flange and can maintain this pressure due to a pressure difference between the two sides of the piston

Furthermore, as stated in claim 3, the invention relates to a shut off valve that is suited for use with the method, said shut off valve being mounted in a tube flange and comprising a centre tube that can be connected to the tube flange, said centre tube and tube flange in this way constituting a closable flow channel. The special feature of the shut off valve is that an alternative flow channel comprises a closable annular passage between a first end of the centre tube and the tube flange. By means of its location near the shut off valve, this alternative flow channel makes it possible that flow through the alternative flow channel can help to clean the active surfaces of the shut off valve. When the shut off valve is closed, inflowing cleaning liquid can flow through the centre tube and hit the closed surface of the shut off valve and thereafter be discharged through the radially oriented alternative flow channel. But the alternative flow channel can also be used for discharge of cleaning liquid during opening and closing of the shut off valve, as the liquid is directed through the shut off valve for cleaning of valve seats and other parts thereof.

As stated in claim 4, it is preferred that the centre tube is mounted in an axially movable manner in a cylinder that is connected to the tube flange, and that an annular piston with two axial sides is fastened axially to and surrounds the centre tube and forms a sealing surface against the inner side of the cylinder, so that a pressure difference between the two axial sides of the piston will move the centre tube towards or away from the tube flange. In this way, it is possible, by means of for instance pneumatics or hydraulics, in a simple way to control the position of the centre tube in such a way that a cleaning cycle can be established via connection of a process plant in which the shut off valve is located to a signalling device such as a computer or another control system.

In claim 5 it is stated that a piece of tube is provided with connection to the tube flange and surrounds the centre tube, which surrounds the alternative flow channel and is fastened to the cylinder, said cylinder furthermore comprising sealing means against an external side of the centre tube in such a way that the centre tube is axially displaceable in relation to the cylinder. In this way it is achieved that the flow in the alternative flow channel is separated from the fluid pressure that is established on the first or the second side of the annular piston.

As stated in claim 6, a seat sealing is provided in the area between the first end of the centre tube and the tube flange. In this way it is insured that when the alternative flow channel is closed it will be hermetically shut off from the centre tube and into the alternative flow channel, and by providing the seat sealing in a suitable plastic material a good wear resistance and durable sealing ability is achieved. As stated in claim 7, the shut off valve that is mounted in the tube flange is a butterfly valve. This type of valve has a simple construction and can be used in many applications. Furthermore, it has a valve flap that, during the cleaning process, can be aligned with the flow of cleaning liquid so that both sides of the valve flap can be cleaned at the same time that the valve seat is being cleaned.

As stated in claim 8, the tube piece is fastened against the tube flange via a first bolted connection, and that the cylinder is coupled to the tube flange via a second bolted connection between the cylinder and the tube piece. Bolted connections ensure elements that can be separated easily and, at the same time, the single parts of the shut off valve are geometrically simple and easy to manufacture, for instance by means of machining processes.

In the following, the invention will be explained in further detail referring to the drawings in which:

Fig. 1 shows a cross sectional view of the shut off valve,

Fig. 2 shows a 3D view of the shut off valve,

Fig. 3 is a sectional end view with both the shut off valve and the alternative flow duct closed,

Fig. 4 is a sectional end view with the shut off valve in closed position, but with the alternative flow duct open,

Fig. 5 is a sectional end view with the shut off valve in open position and the alternative flow duct closed,

Fig. 6 is a sectional end view with the shut off valve in open position, but with the alternative flow duct closed,

Fig. 7 is a sectional view of a plant with a shut off valve mounted, and

Fig. 8 is an enlarged circular section of Fig. 7 with the shut off valve shown in a sectional view. A shut off valve according to the invention can for instance be used in plants of the type that is shown in Fig. 7. Here, a closed mixing tank 18 is provided with an inlet 19 in the bottom, the flow through the inlet being controlled by a shut off valve 1 which is shown in the enlarged sectional view in Fig. 8. The shut off valve 1 is via a flexible hose 20 connected to a holding container 21 which, as shown in Fig. 7, is funnel shaped so that a powder material (not shown) in the container is directed with a certain pressure towards the hose connection 20 by means of gravity to the shut off valve 1 . Pressure differences between the mixing tank and the holding container can now together with the position of the shut off valve control the flow of powdery material to the mixing tank 18. Over time, in this type of plant a coating of the powdery material will build up on the internal surfaces with which it is in contact, and as a result it is necessary that the plant comprises means to enable cleaning thereof at a suitable time, for instance when changing form one batch to another, or when there is a risk of settled powder is turning rancid or is broken down in other ways and subsequently ends up in the mixing tank.

When the shut off valve 1 , the funnel shaped holding container 21 and the duct connection 20 between the two is to be cleaned, the shut off valve 1 is closed, and an alternative flow duct 5 which goes all the way around along a connection flange of the shut off valve 1 is opened. In this way, a rinsing agent can be added via a spray ball 22 and flow from the funnel shaped holding container 21 through the duct connection 20 and all the way to the closed shut off valve 1 and flow radially from here into the alternative flow channel 5, where at least the part of the shut off valve that is facing away from the closed mixing tank 18 is exposed to the rinsing agent and in this way is cleaned of coatings. If the different sealing surfaces of the shut off valve and the side thereof facing the mixing tank are also to be cleaned, this can happen by briefly opening the valve 1.

This process is also called CIP which means Cleaning in Place. By this process the valves, tube and containers are cleaned without having to be dismantled. In Fig. 7, the spray ball 22 is shown inside the funnel shaped holding container 21 and, in this way, it helps to clean the funnel shaped holding container 21 .

The CIP agent is guided through the alternative flow duct 5 of the valve via a side socket 23 and out through a pump 24. From here, the liquid can be directed to cleaning or discharged to a recipient.

In the next step of the cleaning, hot steam is added through the alternative flow duck 5, and in Fig. 7 a steam connection 25 for this purpose is shown. The steam rinses the holding container 21 , the hose 20 as well as the piece between the shut off valve 1 and the connection for the hose 20. The hot steam partly ensures a heating of the parts of the plant and partly a sterilisation of the parts with which the steam enters into contact with.

In a last rinsing step the plant must be dried out and this happens by closing the alternative flow channel, and a certain degree of vacuum is established in the mixing tank 18 so that all remnants of steam or water is sucked out this way as the shut off valve is open in this process step. Optionally, the drying air can be sucked out through the funnel shaped holding container 21 thereby ensuring that all surfaces become totally dry. After the drying is completed, the plant can be used again. In Figs. 3-5 the different positions which the opening of the alternative flow channel 5 and the shut off valve 1 enables are shown. In Figs. 3 and 4 the shut off valve 1 is closed and the alternative flow channel is closed in Fig. 3 and open in Fig. 4. In Figs. 5 and 6 the shut off valve 1 is open and in Fig. 5 the alternative flow channel is shown in closed position and in Fig. 6 it is shown in open position.

Opening and closing of the alternative flow channel 5 takes place by moving the centre tube 3 in the axial direction thereof in relation to the tube flange 4, so that one end 1 1 thereof is at a distance from the sealing 15 or abuts it. The centre tube 3 is at the other end thereof coupled to a flexible hose 20 or a movable tube so that the movement of the centre tube can be accommodated.

An annular piston 6 is mounted around the centre tube 3, which internally is coupled in the axial direction to the centre tube so that this piston 6 and the centre tube 3 are moved as one unit, said piston externally having sealing means in the radial direction that seals towards the inner surface of a cylinder 7. The cylinder 7 is fastened directly or indirectly in the axial direction to the surrounding tube flange 4. The piston has a first axial side 8 and opposite this a second axial side, which both are exposed to pressure via each having a connection socket 25, 26 for for instance pressurized air or hydraulic oil. By controlling the pressure difference between the fluid pressures in the two connection sockets in relation to the areas of the two annular piston sides 8, 9 is it possible to obtain a resultant force on the piston in the axial direction and, in this way, the axial position of the centre tube 3 can be affected. The fluid that is circulated to the two cavities in connection with the respective side of the annular piston 6 is separated from the flow duct via suitable sealings between the centre tube and inwardly facing flanges on the cylinder 7.

When the centre tube 3, as shown in Fig. 6 and Fig. 4, is displaced from the seat sealing 15, the alternative flow channel 5 will be open and, as shown, this flow channel comprises an annular area that is formed by a piece of tube 13 that surrounds the centre tube 3. Furthermore, the piece of tube 13 comprises a suction socket 23 so that a fluid passage from the flow channel 10 and out into the alternative flow channel 5 is established radially in relation to the centre tube. In this way, it is possible to let rinsing liquid flow through the centre tube 3 and out into the alternative flow channel with the shut off valve closed, as it is shown in Fig. 4, to thereby rinse the parts of the shut off valve that faces the centre tube. During such a rinsing process, the shut off valve can be made to change to also rinse the valve seat as well as parts of the valve which otherwise, in the closed position thereof, are facing away from the centre tube.

It should be noted that the suction socket 23, via a valve and a duct connection with a cleaning tube 27 to a pump 24, can be provided with a suitable vacuum so that rinsing liquid can be sucked through the system. Liquid is added via a spray ball 22, also shown in Fig. 7, in the holding container 21 . In this way, the whole system can be rinsed with rinsing liquid so that all sediments that the powder in the tank 21 has a tendency to create on the surfaces which it is brought into contact with can be removed.

There is, as can be seen in Fig. 1 , a first bolted connection 16 between an inwardly facing flange of the piece of tube 13 and the surrounding tube flange 4, and there is, as it also can be seen in Fig. 1 , a second bolted connection between the centre tube 3 and the piece of tube 13. Consequently, the cylinder 7, the piece of tube 13 and the surrounding tube flange 4 comprise a unit, and it is in relation hereto that the centre tube 3 is movable.

The shut of valve 1 is shown in Fig. 1 and is here a butterfly valve, but other types of shut off valves could be used. The butterfly valve has a rotatable valve disc and via a spindle 28, which extends radially out through an opening in the surrounding tube flange 4, the valve disc can be rotated and put so that it blocks the opening in the tube flange, which can be seen in Fig. 2, Fig. 3 and Fig. 4. Alternatively, the valve disc can be rotated so that it leaves the opening free, which is shown in Figs. 5 and 6. A flexible sealing 29 is mounted inside the surrounding tube flange 4. In the present embodiment, the tube flange is made out of two parts, with one part facing the closed mixing tank 18 and the other facing the centre tube 3, said flexible sealing 29 also being mounted between the two parts of the tube flange 4. The first bolted connection 16 keeps the two parts of the surrounding tube flange 4 together. Numerals

1 shut off valve

2 process plant

3 centre tube

4 surrounding tube flange

5 alternative flow channel

6 annular piston

7 cylinder

8 first axial side of annular piston

9 second axial side of annular piston

10 closable flow channel

first end of centre tube

12 sealing surface against the inner side of the cylinder

13 piece of tube

14 sealing means against outer side of centre tube

15 seat sealing

16 first bolted connection

17 second bolted connection

18 closed mixing tank

19 inlet

20 flexible hose or tube

21 holding container

22 spray ball

23 suction socket

24 pump

25 connection socket for the first axial side

26 connection socket for the second axial side

27 cleaning tube

28 spindle

29 flexible sealing