WO2012095553A2

WO2012095553A2 - Spray apparatus and spray method for fiber web

Info

Publication number: WO2012095553A2
Application number: PCT/FI2011/051114
Authority: WO
Inventors: Topi Tynkkynen
Original assignee: Metso Paper, Inc.
Priority date: 2011-01-13
Filing date: 2011-12-16
Publication date: 2012-07-19
Also published as: FI20115034A0; FI20115034A; WO2012095553A3; FI125788B; DE112011104726T5; FI20115034L

Abstract

A spray apparatus (10) for fiber web (W) comprises a first spray means (11) which comprises spray nozzles for a first side of the fiber web and a first pressure line (12) for supplying processing medium to the first spray means, and a second spray means (21) which comprises spray nozzles for a second side of the fiber web and a second pressure line (22) for supplying processing medium to the second spray means, for spraying processing medium directly on one surface or both surfaces of the fiber web by means of one or more spray means. The spray apparatus (10) comprises one or more supply and mixing means (13, 13'; 23, 23') which are spray means specific and coupled to respective pressure lines (12, 22) which are spray means specific, for supplying and mixing a mixture agent in the processing medium by means of the supply and mixing means. A spray method for fiber web (W).

Description

SPRAY APPARATUS AND SPRAY METHOD FOR FIBER WEB

TECHNICAL FIELD The invention relates to a spray apparatus and a spray method for a fiber web. The invention relates particularly, though not exclusively, to surface sizing and coating of paper or board.

BACKGROUND ART

Fiber web such as paper or board is in some points of the production process desired to treat with a web strength increasing processing medium such as a liquid size. Processing the web with a size prescribes substantially the strength properties of the end product. Different starches are used mostly as the sizes to be sprayed to which starches many kinds of additives can be added. In some cases, the fiber web is desired to be coated with a coating mixture including pigments. Among other things, the looks and printability of the web can be affected by the coating. This invention is not restricted to any specific size mixture or coating mixture and by the size should be understood all mixtures which are absorbing at least partly in the web to be treated and increasing the strength of the web.

The viscosity of the processing medium is affecting the formation of the sprays in the spray apparatus. The viscosity of the processing medium may also affect the penetration of the processing medium such as the size in the press event after the spraying.

When a different spray treatment is required for the separate sizes of the fiber web, separate machine circulations are arranged for the separate sizes of the fiber web which circulations comprise a machine tank for the processing medium. When there is applied for instance one-sided coloring or a different dry solids contents for the separate sides, own machine circulations have to be built for spray beams of both sides of the fiber web which is expensive and space demanding. A continuous circulating of special chemicals in the machine circulation is not possible in all circumstances. The continuous circulating may be harmful for example because of a dilution of the processing medium mixture.

In the machine circulation on both sides the processing medium is supplied from the machine tank along a long piping to spray nozzles at one side of the fiber web. The processing medium which is recovered from the spraying event may be recycled to the machine tank. The processing media for the separate sides of the fiber web are formed to desired compositions in two machine tanks. Dilution water and desired processing agents are supplied to the machine tanks and mixed in the machine tanks so that suitable properties for the spraying events are achieved for processing media to be sprayed on the separate sides.

When there is desired to make changes to the spraying event, the composition or the viscosity of the processing medium is changed in the machine tank. When changes are made to the processing medium in the machine tank, a specific change will influence with a delay to the spraying event. The delay is longer than desired in many cases. One such case is the so called web stealing case in which the fiber web to be processed has a tendency to stick to a nip roll after a press nip of the spray apparatus. The volume of the machine tank which is used for the actual mixing is affecting the delay of the processing medium change which is influencing the spraying event. Further the volume of the pressure line which is leading from the machine tank to the spray nozzles is affecting the delay. The distance between the machine tank and the spray nozzles is increasing the volume of the pressure line which distance may be for example 20 to 30 m, and for example the volume of necessary actuators such as a pump and a pressure sieve. The change which is made to the composition of the processing medium in the machine tank is influencing the whole amount of the processing medium in the machine tank what is not desired in all circumstances, for example when the change to be made is desired to be temporary or momentary.

The patent publication Fl 121084 B presents a method and an apparatus for treating a paper or board web. A processing mixture is sprayed onto the surface of the web, the web is lead from a press nip and wet processing mixture is pressed to the web in the press nip.

SUMMARY

According to a first aspect of the invention there is provided a spray apparatus for fiber web comprising a first spray means which comprises spray nozzles for a first side of the fiber web and a first pressure line for supplying processing medium to the first spray means, and a second spray means which comprises spray nozzles for a second side of the fiber web and a second pressure line for supplying processing medium to the second spray means, for spraying processing medium directly on one surface or both surfaces of the fiber web by means of one or more spray means. The spray apparatus comprises one or more supply and mixing means which are spray means specific and coupled to respective pressure lines which are spray means specific, for supplying and mixing a mixture agent in the processing medium by means of one or more supply and mixing means.

Preferably the spray apparatus comprises a first supply and mixing means which is coupled to a first pressure line, and/or a second supply and mixing means which is coupled to a second pressure line.

The spray apparatus may comprise several first spray means and/or several second spray means and, respectively, several pressure lines which are spray means specific. Preferably a supply and mixing means is arranged in the spray means specific pressure line or spray means specific pressure lines.

Preferably the spray apparatus is configured to change the composition of the processing medium to be supplied by means of the first and/or second pressure line before the spray nozzles.

Preferably there is one machine circulation in the spray apparatus which machine circulation comprises one machine tank and a supply piping starting from the machine tank by means of which supply piping the processing medium is supplied to the first pressure line and/or the second pressure line.

Preferably the first pressure line and the second pressure line are formed by dividing the supply piping in two pressure lines which supply piping is leading from the machine tank to the first and second spray means. The first pressure line and the second pressure line may be divided in a pressure pipe after a pressure sieve comprised by the spray apparatus.

According to some preferable embodiments the spray apparatus comprises one or more first pressure lines for supplying the processing medium respectively to one or more first spray means, and the spray apparatus comprises one or more second pressure lines for supplying the processing medium respectively to one or more second spray means. Preferably the supply and mixing means comprises as a supply means a mixture agent pipe for supplying the mixture agent to the pressure line. The mixture agent pipe may be coupled directly to the pressure line or a mixing means such as a static mixer. Preferably the mixture agent pipe is coupled to the pressure line before the mixing means.

Preferably the supply and mixing means comprises as the mixing means a static mixer. Preferably the supply and mixing means comprises as the mixing means an injector. Preferably the spray apparatus comprises the pressure sieve and a pressure measurement of the processing medium mixture, a flow measurement and/or a viscosity measurement which measurement/measurements are arranged in a pressure channel after the pressure sieve. Preferably the spray apparatus comprises a pressure measurement of the processing medium mixture, a flow measurement and/or a viscosity measurement which measurement/measurements are arranged in a pressure channel after the supply and mixing means. Preferably the spray apparatus is configured to mix to the first and/or the second pressure line as the mixture agent one or more of the following: dilution water, steam, gas, solid material, starch, native starch, pigment, color agent, carbon dioxide, a chemical, a special chemical.

Several supply and mixing means may be arranged to the first pressure line and/or the second pressure line so that one supply and mixing means is configured to supply and mix one mixture agent at a time in the processing medium.

Preferably the spray apparatus comprises a press nip which is arranged in the travelling direction of the fiber web after the spray means for pressing the processing medium mixture to the fiber web after the spraying. According to a second aspect of the invention there is provided a spray method for fiber web, the method comprising processing the fiber web in a spray apparatus which comprises a first spray means which comprises spray nozzles for a first side of the fiber web and a first pressure line for feeding processing medium to the first spray means, and a second spray means which comprises spray nozzles for a second side of the fiber web and a second pressure line for feeding processing medium to the second spray means, and the processing medium is sprayed directly on one surface or both surfaces of the fiber web by means of one or more spray means, and the spray apparatus comprises one or more feeding and mixing means which are spray means specific and coupled to respective pressure lines which are spray means specific, and the method comprising feeding and mixing a mixture agent in the processing medium by means of one or more feeding and mixing means.

Preferably the composition of the processing medium to be supplied is changed by means of the first and/or second pressure line before the spray nozzles.

Preferably the processing medium is supplied to the first pressure lines and/or the second pressure lines by means of one machine circulation of the spray apparatus which machine circulation comprises one machine tank and a supply piping starting from the machine tank. Preferably the processing medium is supplied to the first pressure line and/or the second pressure line by means of one machine circulation of the spray apparatus which machine circulation comprises one machine tank and a supply piping starting from the machine tank.

Preferably the first pressure lines and the second pressure lines are formed by dividing the supply piping leading from the machine tank to the first and second spray means correspondingly to several spray means specific pressure lines. Preferably the first pressure line and the second pressure line are formed by dividing in two pressure lines the pressure piping which is leading from the machine tank to the first and second spray means.

Preferably the first pressure line and the second pressure line are divided from the pressure pipe after a pressure sieve comprised by the spray apparatus.

Preferably the spray apparatus comprises one or more first pressure lines by which the processing medium is supplied respectively to one or more first spray means, and the spray apparatus comprises one or more second pressure lines by which the processing medium is supplied respectively to one or more second spray means.

Preferably the mixture agent is supplied to the pressure line by means of the supply and mixing means which comprises as a supply means a mixture agent pipe. Preferably the mixture agent is supplied to the pressure line before a mixing means.

Preferably the mixture agent is mixed to the pressure line by means of the supply and mixing means which comprises as the mixing means a static mixer. Preferably the mixture agent is mixed to the pressure line by means of the supply and mixing means which comprises as the mixing means an injector.

Preferably the pressure of the processing medium mixture is measured by a pressure measurement, the flow by a flow measurement and/or viscosity by a viscosity measurement which measurement/measurements are arranged in a pressure channel after a pressure sieve comprised by the spray apparatus.

Preferably the pressure of the processing medium mixture is measured by a pressure measurement, the flow by a flow measurement and/or viscosity by a viscosity measurement which measurement/measurements are arranged in a pressure channel after the supply and mixing means.

Preferably the supply of the mixture agent is adjusted by the supply and mixing means based on pressure, flow and/or viscosity measurements.

Preferably one or more of the following is mixed to the first and/or the second pressure line as the mixture agent: dilution water, steam, gas, solid material, starch, native starch, pigment, color agent, carbon dioxide, a chemical, a special chemical. As the mixture agent may also be used PVA, silicone, coating pasta, latex, pigment-surface size -mixture etc. processing medium to be applied typically on the fiber web.

Preferably the spray apparatus comprises a press nip which is arranged in the travelling direction of the fiber web after the spray means. Preferably the method comprises pressing the processing medium mixture to the fiber web in the press nip after the spraying.

The processing medium can be sieved before the machine tank. Preferably the spray apparatus comprises a sieve which is arranged before the machine tank.

The composition of the processing medium to be sprayed onto the first and/or the second surface can be changed individually. Desired dry solids contents and an eventual one-sided coloring can be achieved for the individual sides with one machine circulation. The composition of the processing medium can be changed quickly near the spraying event. The delay between detecting a requirement for the change and implementing the change can be shortened compared to prior art because the mixing of the mixture agent is not required to be done in a large volume of the processing medium and not far in the machine tank in the beginning of the supply piping. Web stealing can be avoided quickly for example by supplying and mixing dilution water in the pressure line which is leading to the spray means. Water or chemical can be dosed in the pressure line.

The spray apparatus provides for an advantageous possibility to dose special chemicals (so called additives). For example, just a desired amount of special chemicals can be used and the use of special chemicals can be allocated to the spraying event more precise timely and quantitatively. It is not required to mix a color agent or another chemical in the machine tank wherein the required mixture agent can be obtained in use when desired. The spray beams at different sides can be run with different dry solids contents. The viscosity of the processing medium can be lowered if the happen to be problems in size production. The viscosity of the processing medium can be lowered suitable for spraying.

The spraying of the processing medium can be implemented on a sizer, a calender, a wire section, a belt press, a drying section or another paper manufacturing apparatus. As the processed grade can be among others boards, cartonboards, liner, fluting, fine paper, newsprint. The processing medium mixture to be sprayed may be starch, PVA, silicone, coating pasta, latex, pigment-surface size -mixture etc. processing medium to be applied typically on the fiber web. Preferably the processing medium mixture to be applied increases strength of the web. Different embodiments of the present invention will be illustrated or have been illustrated only in connection with some aspects of the invention. A skilled person appreciates that any embodiment of an aspect of the invention may apply to the same aspect of the invention and other aspects alone or in combination with other embodiments as well.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described, by way of example, with reference to Figure 1 of the accompanying drawing which shows a simplified function diagram of a spray apparatus. DETAILED DESCRIPTION

It should be appreciated that the illustrated drawing is not entirely in scale, and that it mainly serves the purpose of illustrating embodiments of the invention. Fig. 1 shows a spray apparatus 10 which comprises one machine circulation 20. Processing agent is sprayed onto a fiber web W by a first spray means 1 1 and/or a second spray means 21 and after that the fiber web is lead through a press nip 15. The processing agent is supplied from a common machine tank 1 by a supply piping to spray beams at both sides of the fiber web and the composition of the processing medium can be changed by supplying and mixing a mixture agent or mixture agents in a branch or branches 12, 22 of a supply line 7 which is/are leading to the spray beam/spray beams.

The spray apparatus comprises a first pressure line 12 which is leading to a first spray means 1 1 . The spray apparatus comprises a first supply and mixing means which is arranged to the first pressure line 12. The first supply and mixing means comprises a first static mixer 13 and a first mixture agent line 13'. The first mixture agent line 13' is leading to the first pressure line 12 before the first static mixer 13 or directly to the first static mixer 13.

The spray apparatus comprises a second pressure line 22 which is leading to a second spray means 21 . The spray apparatus comprises a second supply and mixing means which is arranged to the second pressure line 22. The second supply and mixing means comprises a second static mixer 23 and a second mixture agent line 23'. The second mixture agent line 23' is leading to the second pressure line 22 before the second static mixer 23 or directly to the second static mixer 23.

According to some embodiments the spray apparatus comprises several supply and mixing means which are coupled to the first and/or second pressure lines so that one mixture agent is mixed to the processing medium by each supply and mixing means. In the embodiment shown in Fig. 1 , one or more mixture agents can be supplied and mixed by one mixer to the processing medium of one pressure line. The volume flows of the mixture agents to be mixed are typically small wherein the required devices are small.

The spray apparatus 10 comprises two press members which are loadable against each other, a first roll 14 and a second roll 24. The press members 14, 24 are forming the press nip 15 there between. The spray apparatus comprises as the first spray means a first spray beam 1 1 for the first side of the fiber web and as the second spray means a second spray beam 21 for the second side of the fiber web. A paper or board web W is lead in the press nip 15 after the spraying of the processing medium mixture onto the web. The spray apparatus 10 comprises first spray nozzles in the first spray beam 1 1 and second spray nozzles in the second spray beam 21 . The web can be, for example, size processed with a size mixture or coated with a coating mixture one-sided by the first spray nozzles, or two-sided by the first spray nozzles and the second spray nozzles. It is also possible to use a belt as the press member. Preferably the belt is lead through a roll nip.

One machine circulation 20 is arranged in the spray apparatus 10 which machine circulation comprises the machine tank 1 for the processing medium and a supply piping for leading the processing medium from the machine tank to the spraying event. The processing medium is mixed in the machine tank 1 to a desired basis composition and basis viscosity before the leading of the processing medium mixture to the supply piping which is leading to the spray nozzles. Processing medium and dilution water can be supplied to the machine tank 1 through an inlet pipe 2. Processing medium can be lead to the inlet pipe for example from a processing medium storage tank and warm dilution water can be mixed to the machine tank. The supply piping comprises a supply pipe 3 for leading the processing medium from the machine tank to a pressure pump 4 comprised by the spray apparatus. Preferably the processing medium mixture such as a size mixture is pumped through a pressure sieve 6. The supply piping comprises a first pressure pipe 5 for leading the processing medium from the pressure pump 4 to the pressure sieve 6. Further the supply piping comprises a second pressure pipe 7 which is starting from the pressure sieve 6 to the spray means 1 1 , 21 .

The machine circulation 20 is common for the first and second spray means until that point where the supply piping, preferably the second pressure pipe 7, is divided in individual pressure lines 12, 22 to which mixture agent lines 13', 23' are coupled as supply means and static mixers 13, 23 as mixing means. The machine circulation 20 is divided in individual pressure lines before the spray means so that the compositions and/or the viscosities of the processing medium mixtures to be supplied to both spray means can be changed individually.

The spray apparatus 10 comprises a pressure measurement in the pressure channel after the pressure sieve 6, preferably a first pressure measurement 16 in the first pressure channel 12 and a second pressure measurement 26 in the second pressure channel 22. The spray apparatus 10 may comprise a viscosity measurement and/or the pressure measurement in the pressure channel after the pressure sieve 6, preferably a first viscosity measurement and/or the first pressure measurement in the first pressure channel 12 and a second viscosity measurement and/or the second pressure measurement in the second pressure channel 22. The dilution of the processing medium mixture proceeding to the spray beams 1 1 , 21 may be arranged computationally based on pressure, flow and/or viscosity measurements. The amount of size used for the web is known when the flow arriving to the beam and the return flow departing from the beam are measured. Dilution water 13', 23' proceeding to the spray beams can be added to the line after the pressure sieve according to calculated dilution requirement.

After the dilution separate viscosity measurements can also be arranged for both spray beams 1 1 , 21 . The dilution of the processing medium mixture proceeding to the spray beams can be arranged adjusted by an optional viscosity measurement after the dilution 13', 13; 23', 23 (not shown in the figure).

The supply piping of one machine circulation can also be divided in more than two branches for forming individual pressure lines in the end of the supply. In other words, the supply piping may be branched for several spray means such as spray beams. In one exemplary case one first spray means is arranged on one side of the fiber web and on the other side two second spray means are arranged successively. Thus, several spray beams can be supplied by one machine circulation and there may be more than three spray beams as described in this example.

The machine circulation 20 comprises a return flow. The machine circulation is common for the first and second spray means also regarding the return flow after the spraying event. The return flow comprises a return pipe 8 which is leading back to the machine tank 1 . The return flow comprises a first return line 31 which is leading from the first spray beam 1 1 to the return pipe 8, and a second return line 32 which is leading from the second spray beam 21 to the return pipe 8. One or the other return pipe or both return pipes can be closed if necessary or the spray beam in question can be supplied at both ends. A minor return flow from the spray beam may be required for that reason that the end of the spray pipe comprising spray nozzles is not left without flow, for example, returning of water or color agent back to the machine tank does not harm the process very much. For example when coloring is used, the return flow can be closed or it is scaled down to be substantially small that the color agent does not change the color of the whole liquid in the machine tank. Embodiments of the spray apparatus and the spray method are advantageous in connection with individual treatments of separate fiber web sides because for instance when a one-sided coloring or different dry solids contents of the different sides is used one can use one machine circulation for spray beams of both sides which is lowering costs and reducing space requirement. When special chemicals are used one can reduce the harm caused by the recycling of the special chemicals. When special chemicals are used the return circulation can be closed. The dilution of the processing medium mixture due to continuous recycling of special chemicals can be avoided.

The processing medium which is recovered from the spraying event can be recycled back to the machine tank 1 also via the return pipe 8. The return circulation comprises a collecting pipe 33 and a mist separator 34. The recovered liquid and mist-like processing medium is led through the collecting pipe 33 to the mist separator 34 which may be a cyclone. After the mist separator the liquid processing medium is lead to the return pipe and the mist-like processing medium may be lead to a mist washing apparatus 40 via a mist channel 41 . The processing medium which is changed to liquid form can be returned from the mist washing apparatus 40 back to the machine tank 1 through the return pipe 8.

The processing medium can be sieved before the machine tank 1 . The processing medium which is recovered from the spraying event can be sieved before return to the machine tank 1 , for example with a sieve which is arranged in the return pipe 8.

An example of controlling the amount of starch i.e. the dry solids content of the size is described in the following. In the machine tank, the dry solids content of the processing medium mixture is arranged to be 15%. The processing medium mixture is distributed to the first spray beam 1 1 and to the second spray beam 21 in dry solids contents 15% and 20%. The processing medium mixture supplied to the first spray beam 1 1 is not diluted. Dilution water is supplied through the second supply means 23' (the second mixture agent pipe) to the second pressure line 22 which is leading to the second spray beam 21 and the dilution water is mixed in the second mixing means 23 ( the second static mixer) so that dry solids content of 10% is reached. The return flow 31 , 32, 33 from both spray beams 1 1 , 21 would be 10% of the total amount (of the total amount of the dry solids content 15% and dry solids content 10%), that is in total 20% of the total amount in an average dry solids content of 12,5%. An amount of 80% of the total amount which is all the time exiting with the web is entering the machine tank 1 through the inlet pipe 2 with a dry solids content of 15%. As a result the processing medium mixture in the machine tank 1 is diluted a little what can be compensated by increasing the dry solids content of the processing medium mixture which is added to the machine tank. For example mixing of steam to the pressure line 12, 22 has been observed in practice to warm up but not significantly dilute the processing medium mixture. Correspondingly, when steam is used as mixture agent, an amount of 100% which is exiting with the web is all the time supplied to the machine tank 1 in dry solids content of 15%, i.e. the starch of the machine tank is diluted a little what can be compensated.

The foregoing description provides non-limiting examples of some embodiments of the invention. It is clear to a person skilled in the art that the invention is not restricted to details presented, but that the invention can be implemented in other equivalent means. Some of the features of the above-disclosed embodiments may be used to advantage without the use of other features.

As such, the foregoing description shall be considered as merely illustrative of the principles of the invention, and not in limitation thereof. Hence, the scope of the invention is only restricted by the appended claims.

Claims

1 . A spray apparatus (10) for fiber web (W) comprising a first spray means (1 1 ) which comprises spray nozzles for a first side of the fiber web and a first pressure line (12) for supplying processing medium to the first spray means, and a second spray means (21 ) which comprises spray nozzles for a second side of the fiber web and a second pressure line (22) for supplying processing medium to the second spray means, for spraying processing medium directly on one surface or both surfaces of the fiber web by means of one or more spray means, characterized in that the spray apparatus (10) comprises one or more supply and mixing means (13, 13'; 23, 23') which are spray means specific and coupled to respective pressure lines (12, 22) which are spray means specific, for supplying and mixing a mixture agent in the processing medium by means of one or more supply and mixing means.

2. The spray apparatus according to claim 1 , characterized in that the spray apparatus (10) comprises a first supply and mixing means (13, 13') which is coupled to a first pressure line (12), and/or a second supply and mixing means (23, 23') which is coupled to a second pressure line (22).

3. The spray apparatus according to claim 1 or 2, characterized in that the spray apparatus (10) is configured to change the composition of the processing medium to be supplied by means of the first and/or second pressure line (12, 22) before the spray nozzles.

4. The spray apparatus according to any of claims 1 to 3, characterized in that there is one machine circulation (20) in the spray apparatus (10) which machine circulation comprises one machine tank (1 ) and a supply piping starting from the machine tank by means of which supply piping the processing medium is supplied to the first pressure line (12) and/or the second pressure line (22).

5. The spray apparatus according to any of claims 1 to 4, characterized in that the first pressure line (12) and the second pressure line (22) are formed by dividing the supply piping in two pressure lines which supply piping is leading from the machine tank (1 ) to the first and second spray means (1 1 , 21 ).

6. The spray apparatus according to claim 5, characterized in that the first pressure line (12) and the second pressure line (22) are divided in a pressure pipe

(7) after a pressure sieve (6) comprised by the spray apparatus.

7. The spray apparatus according to any of claims 1 to 6, characterized in that the spray apparatus comprises one or more first pressure lines (12) for supplying the processing medium respectively to one or more first spray means (1 1 ), and the spray apparatus comprises one or more second pressure lines (22) for supplying the processing medium respectively to one or more second spray means (21 ).

8. The spray apparatus according to any of claims 1 to 7, characterized in that the supply and mixing means comprises as a supply means a mixture agent pipe (13', 23') for supplying the mixture agent to the pressure line.

9. The spray apparatus according to any of claims 1 to 8, characterized in that the supply and mixing means (13, 23) comprises as the mixing means a static mixer.

10. The spray apparatus according to any of claims 1 to 9, characterized in that the spray apparatus comprises the pressure sieve (6) and a pressure measurement (16, 26) of the processing medium mixture, a flow measurement and/or a viscosity measurement which measurement/measurements are arranged in a pressure channel (12, 22) after the pressure sieve (6).

1 1 . The spray apparatus according to any of claims 1 to 10, characterized in that the spray apparatus comprises a pressure measurement (16, 26) of the processing medium mixture, a flow measurement and/or a viscosity measurement which measurement/measurements are arranged in a pressure channel (12, 22) after the supply and mixing means (13, 23).

12. The spray apparatus according to any of claims 1 to 1 1 , characterized in that the spray apparatus is configured to mix to the first and/or the second pressure line as the mixture agent one or more of the following: dilution water, steam, gas, solid material, starch, native starch, pigment, color agent, carbon dioxide, a chemical, a special chemical.

13. The spray apparatus according to any of claims 1 to 12, characterized in that several supply and mixing means are arranged to the first pressure line and/or the second pressure line so that one supply and mixing means is configured to supply and mix one mixture agent at a time in the processing medium.

14. The spray apparatus according to any of claims 1 to 13, characterized in that the spray apparatus comprises a press nip (15) which is arranged in the travelling direction of the fiber web after the spray means (1 1 , 21 ) for pressing the processing medium mixture to the fiber web after the spraying.

15. A spray method for fiber web (W), the method comprising processing the fiber web (W) in a spray apparatus (10) which comprises a first spray means (1 1 ) which comprises spray nozzles for a first side of the fiber web and a first pressure line (12) for feeding processing medium to the first spray means, and a second spray means (21 ) which comprises spray nozzles for a second side of the fiber web and a second pressure line (22) for feeding processing medium to the second spray means, and the processing medium is sprayed directly on one surface or both surfaces of the fiber web by means of one or more spray means, characterized in that the spray apparatus (10) comprises one or more feeding and mixing means (13, 13'; 23, 23') which are spray means specific and coupled to respective pressure lines (12, 22) which are spray means specific, and the method comprising feeding and mixing a mixture agent in the processing medium by means of one or more feeding and mixing means.

16. The method according to claim 15, characterized in that the spray apparatus (10) comprises a first supply and mixing means (13, 13') which is coupled to a first pressure line (13), and/or a second supply and mixing means (23, 23') which is coupled to a second pressure line (22).

17. The method according to claim 15 or 16, characterized by changing the composition of the processing medium to be supplied by means of the first and/or second pressure line before the spray nozzles.

18. The method according to claim 17, characterized by supplying the processing medium to the first pressure line (12) and/or the second pressure line (22) by means of one machine circulation (20) of the spray apparatus (10) which machine circulation comprises one machine tank (1 ) and a supply piping starting from the machine tank.

19. The method according to any of claims 15 to 18, characterized by forming the first pressure line (12) and the second pressure line (22) by dividing in two pressure lines the supply piping which is leading from the machine tank (1 ) to the first and second spray means (1 1 , 21 ).

20. The method according to any of claims 15 to 19, characterized by dividing the first pressure line (12) and the second pressure line (22) from the pressure pipe (7) after a pressure sieve (6) comprised by the spray apparatus.

21 . The method according to any of claims 15 to 20, characterized by supplying the mixture agent to the pressure line (12, 22) by means of the supply and mixing means (13, 23) which comprises as a supply means a mixture agent pipe (13', 23').

22. The method according to any of claims 15 to 21 , characterized by mixing the mixture agent to the pressure line (12, 22) by means of the supply and mixing means (13, 23) which comprises as the mixing means a static mixer.

23. The method according to any of claims 15 to 22, characterized by measuring the pressure of the processing medium mixture by a pressure measurement (16, 26), the flow by a flow measurement and/or viscosity by a viscosity measurement which measurement/measurements are arranged in a pressure channel (12, 22) after a pressure sieve (6) comprised by the spray apparatus.

24. The method according to any of claims 15 to 23, characterized by measuring the pressure of the processing medium mixture by a pressure measurement (16, 26), the flow by a flow measurement and/or viscosity by a viscosity measurement which measurement/measurements are arranged in a pressure channel (12, 22) after the supply and mixing means (13, 23).

25. The method according to claim 23 or 24, characterized by adjusting the supply of the mixture agent by the supply and mixing means based on pressure, flow and/or viscosity measurements.

26. The method according to any of claims 15 to 25, characterized by mixing one or more of the following to the first and/or the second pressure line as the mixture agent: dilution water, steam, gas, solid material, starch, native starch, pigment, color agent, carbon dioxide, a chemical, a special chemical.

27. The method according to any of claims 15 to 26, characterized in that the spray apparatus (10) comprises a press nip (15) which is arranged in the travelling direction of the fiber web after the spray means (1 1 , 21 ) and the method comprising pressing the processing medium mixture to the fiber web in the press nip after the spraying.