DE2038758A1 - Method and device for removing a condensate from a drying drum - Google Patents

Description

Patent attorneys,

, Wilhelm Lnc: c

• 6381 INTERNATIONAL PAPER COMPANY, New York, V.St.A. '

Method and device for removing a condensate from a drying drum

The invention relates to a method and a device for removing a condensate, which as an edge sits on the inner surface of the shell of a drying drum, wherein the jacket can accommodate pressurized steam in its hollow inner space, whereby the jacket is heated to dry the material running around the peripheral surface will result in the formation of a condensate inside the jacket leads and in which the condensate is discharged and discharged into the jacket by the steam through several openings in an exhaust pipe the coat is challenged, with the openings next to the inner surface of the shell are provided and move with this. The invention relates in particular "

to a method and apparatus whereby the removal of the condensate is supported in that the Entrainment of the condensate in steam, which the inside of the Mantle leaves is reinforced.

In certain drying drums, for example drying cylinders for paper machines, steam is introduced under pressure into the hollow interior of a drying jacket, whereby the 'jacket is heated to an elevated temperature which is sufficient to' the material, e.g. a paper tissue, which along the outer surface of the jacket is led to dry. The steam condenses to a condensate when the heat is given off to the jacket. The drying cylinders are running at such high speeds

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rotated so that the resulting condensate forms an edge inside the cantilever; that is, centrifugal force holds the liquid condensate against the inner surface of the shell as the shell rotates. The condensate is drained from the inside surface of the jacket through an outlet device located adjacent the inside surface of the jacket which uses the vapor pressure within the jacket to evacuate the condensate into and out of the jacket.

The difficulty with the previously known outlet devices is that they do not contain large amounts of condensate can effectively remove. For more economical operation, it is desirable to use paper machines with ever greater speeds to operate. As a result, faster drying of the paper web by the drying cylinders is necessary. A faster one Drying can be achieved by increasing the steam pressure in the drying jacket to increase the drying cylinder temperature; ,However faster drying leads to an increase in the amount of condensate formed, which then increases at a greater rate must be removed. It has been found that the high speed at which the condensate is removed is a limiting factor in increasing the operating speed of paper machines.

The inventive method to overcome these disadvantages is characterized in that the steam flow on a considerable distance along the surface of the condensate in the jacket and that the steam is a pressure gradient is supplied so that when it approaches the openings, it receives a sufficient speed that it is water from the inside surface of the jacket so that water is entrained in the steam as the steam passes through the openings flows. -

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A device for removing condensate from a drying drum according to the method described above is characterized in that a discharge pipe is arranged in the jacket and extends essentially over the entire length of the jacket and is connected to the outside of the jacket, that the discharge pipe is in communication with the interior of the jacket through a plurality of openings for fluid passage, which are spaced along the discharge pipe next to the inner surface of the jacket at a certain distance and rotate with the latter, so that the device condensate in the steam which is in the openings vcm inside the Jacket enters, can entrain, and that guide devices are provided, which form elongated drainage channels for ■ the Daa.pf and which for a considerable distance and opposite other openings extend substantially parallel to the inner surface of the jacket, whereby the steam emerging from the interior of the Mantle is moved to the openings, along the surface e of the condensate moves so that water from the. Inner surface of the jacket sheared and is entrained in the steam as it flows through the openings.

Thus, according to the invention, the limitations are the known ones Devices overcome in that the entrainment of condensate in the steam emitted from the interior of the jacket, is reinforced. The steam is so curled that it is for a considerable distance along the surface of the condensate within of the coat flows. The steam is pressurized enough to move at speeds at which it is Water shears off the inside surface of the jacket and in which the steam carries water with it as it leaves the inside of the jacket. In particular, the steam is accelerated when it is moved along the surface of the condensate in a plurality of openings which are mounted along a drainage pipe, which extends over the entire length of the drying dumbbell. Of the Accelerated steam exerts a shear force on the surface of the condensate, causing the condensate to reach the openings is accelerated towards. The speed of the turbulent flow

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BATH ORIGINAL

tion of the condensate is increased until the water is entrained in the steam will. As the steam is accelerated, continuous entrainment of condensate is ensured.

It is therefore the main object of the invention to provide a method and an apparatus for removing condensate, which is based on the Inner surface of a drying cylinder jacket forms an edge,

by passing steam along the surface of the condensate for a considerable distance at a rate which is sufficient to shear the water from the inner surface of the mantle and entrain the water in the steam, if the steam emerges from the interior of the drying cylinder jacket. It is another object of the invention to provide such a method and to provide a device in which the steam is passed through drainage channels the cross-sectional area of which is reduced, so that the steam is accelerated when it leaves the interior of the drying cylinder jacket, whereby a continuous Entrainment of the condensate in the steam is ensured.

Embodiments of the invention are described below by way of example with reference to the drawings. Show:

Figure 1 is a representation, partly in section and partly schematically a drying cylinder in which the condensate removal device according to the invention is used,

FIG. 2 shows a section through the drying cylinder according to FIG. 1 along the line 2-2 in FIG. 1,

Figure 3 is an enlarged partial section of a discharge pipe and a plate provided with openings, which are shown in Figure 2,

Figure 4 is a view of an apertured plate as shown in Figure 3;

Figure 5 is a perspective view of the apertured plate shown in Figure 3;

FIG. 6 shows an enlarged partial view of another embodiment of the discharge pipe and the discharge plate and FIG

FIG. 7 shows a plan view of a discharge pipe and one with an opening Fitted plate according to Figure 6.

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In Figures 1 and 2 is a drying cylinder 10 with a Shown water extraction device according to the invention. The drying cylinder has a cylindrical jacket 12 which is closed at its ends by end closures 14 and 16 is. The drying cylinder is rotatably supported in bearings 18 and 20 and is driven by a drive device via a gear 22 turned. Steam under pressure is introduced into the interior of the shell 12 from an external steam boiler. Of the Steam is supplied from a supply line 24 through a rotatable coupling 26 which connects the fixed supply line 24 with an annular passage 28 in it rotating end closure 16 connects, wherein the steam flow "

towards the outside air and towards the vented steam is sealed. The vapor pressure in the jacket 12 is controlled by a shut-off device 30 and by a pressure gauge 32 measured.

In a papermaking machine, a wet web to be dried is wrapped around the outer surface of the shell.

12 shown around. The pressurized steam heats the jacket 12, transferring thermal energy to the outer surface of the jacket. The heat of the jacket 12 then passes into the web and evaporates the water contained therein, thereby drying the web. By transferring the heat energy of the vapor, etc. to the web is cooled the steam and thereby water deposited on the inner surface of the shell 12th In the case of high-speed paper machines, as considered here, the condensation forms a band on the jacket. That is to say, it is pressed against the jacket by the centrifugal force which is caused by the rotation of the jacket 12 at high speed.

For the Troekenzylirider to work effectively, it is necessary to remove the condensed water from the inner surface of the shell 12. This is achieved in that the condensed Water or the condensate, with the help of the steam

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Drainage pipes 34 which are attached adjacent to the inner surface of the shell 12 and rotate with this. the Drainage pipes 34 can be fastened with the aid of struts 36 to a middle piece 38 which is located between the end closures 14 and 16 runs. The discharge pipes 34 are arranged and run at regular intervals on the inner circumference of the jacket substantially the full length of the jacket 12. As will be described in more detail below, Due to the steam pressure in the jacket 12, the steam from the interior of the jacket 12 into the corresponding discharge pipes 34 displaced, taking condensed water with it. The steam and condensate pass from the discharge pipes 34 Discharge outlets 40 and then through an outlet 42 which passes through the center of the steam passage 28. The outlet 42 is connected by the rotatable coupling 26 to an outlet pipe 44 through which the steam and condensate as Waste can be disposed of or fed back into the system. The amount of inflow from jacket 12 into the exhaust system Steam is controlled by a valve 46 in the outlet line. The outlet vapor pressure can be measured by a pressure gauge be measured. The difference in the pressures in the pressure gauges 32 and 48 is a measure of the pressure range used by the steam moves through the drying cylinder and thus takes the condensate from the interior of the jacket 12 with it.

As the discharge pipes 34 rotate with the jacket 12, condensate-r sat through them only in the vicinity of the discharge pipes 34. However, due to the force of gravity and the rotation of the shell 12, the Condensate will flow around the inner surface of the shell 12 so that it will flow to the drainage pipes 34 from which j is drained. In addition, the condensate flows in such a way that the condensate layer at the upper end of the jacket 12 is thicker. This is by gravity conditionally, which slows down the condensate when it is moved upwards and accelerates it when it moves downwards so that "more condensate collects at the upper end.

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The auxiliary figures 3 to 5 show a in more detail preferred embodiment of the water extraction device by which the condensed water or the condensate is entrained with the steam that is given off. One with openings Plate 50 is attached to the outer surface of each downcomer 34. Each apertured plate 50 is from a plurality of openings 52 passes through which are arranged at a distance from the discharge pipe 34 and a fluid connection between the interior of the hanteis 12 and the interior of the corresponding discharge pipe 34. The openings 52 are preferably evenly spaced along the entire length of each downcomer 34 with the exception that the location of the openings at the ends is somewhat are modified so that the conditions on the edge are met. For example, additional end openings 54 can be added. The openings 52 are adjacent to the inner surface of the Kanteis 12 and they have a distance of about 0.15 cm to 0.3 cm therefrom.

To the respective openings 52 run outflow channels 56-, the through the outer wall ^ eder provided with plate 50 and the inner surface 60 of the shell are formed. Any channel 56 runs essentially parallel to the inner surface 60 of the shell 12 and consequently essentially parallel to that Surface of the condensate on it. This causes the steam train to run for a considerable distance along the Surface of the condensate passed, reducing the flow of steam for a considerable time and for a considerable amount of time Length can act on the condensate. The vapor pressure gradient causes the steam to sweep over the condensate and shear forces which accelerate the condensate towards the openings 52 until the condensate is removed from the surface of the jacket 12 is sheared off and carried away with the steam. An entrainment of the condensate by the steam results when that Condensate flows turbulently at a speed of more than 4.5 m / sec. The steam must have a sufficiently large pressure gradient

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to achieve this speed. Purely an effective way of working, the drainage channels 56 should be about Be 1.25 cm long. On the other hand, if the length of the drainage channels 56 is greater than about 10 cm, then agitation can occur.

In the embodiment shown in FIGS. 3 to 5, the cross section of each channel decreases in the direction of the steam flow. As a result, the steam is steadily accelerated as it approaches the corresponding openings 52. In this way, the condensate is accelerated relatively gradually towards the openings at the beginning of the drainage channels, with the shear forces steadily increasing in the direction of the openings 52. The condensate is thus accelerated until there is sufficient turbulence so that the condensate is sheared off the jacket 12 and is entrained by the steam. Since the steam is constantly accelerated, the condensate that is once entrained remains in the steam flow.

When the steam and condensate have passed the openings 52, they move through inlet tubes 62 into the interior of the discharge tubes 34. Outlet tubes 64 protrude into the associated discharge tubes 34 from respective discharge outlets 40. Each outlet tube 64 protrudes outwardly beyond the inwardly directed ones Ends of the inlet pipes 62 out. The outlet pipes 64 project up next to the WANs the outlet pipes 34 and of these have a distance of about 0.3 cm, -The entire cross-sectional area of the outlet pipes 64 is less than the total cross-sectional area of the inlet pipes 62. As a result, an acceleration of the vapor is achieved when he leaves the discharge pipes 34, whereby a wide res entrainment of the condensate is ensured in the steam flow.

Since the discharge pipes 34 and the openings 52 move with the inner surface of the edge ice 12, the condensate can be taken up from both directions perpendicular to the discharge pipes 34.

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increases that the drainage channels in both perpendicular directions from each opening 52, as shown in FIGS. 3 to 5 is to be provided.

Another embodiment horn of the arrangement according to the invention is shown in FIGS. 6 and 7. Quite general is this embodiment does not do so when removing condensate effective, like the embodiment shown in FIGS. 3 to 5. However, it is particularly suitable for installation in certain drying cylinders. In the embodiment shown in Figures 6 and 7, the drainage channels 56 have in essentially constant cross-section and only one channel protrudes to each opening. Furthermore, the device has no outlet pipes; die'Ableitauslasst 40 are rather directly with the Ends of the discharge pipes 34 connected.

Empirical data that have been obtained in various comparative tests show the improved efficiency and the improved effect of the various embodiments of the condensate extraction device. The best representation was probably obtained through tests that were carried out before and after the conversion of a particular drying cylinder. These experiments were carried out with a paper machine, which had a drying cylinder having a diameter of about 5 m (15 feet) ä. The paper machine was operated at a straight line speed of about 750 m / min to produce crepe fabric with a basis weight of about 6 kg (basis weight of about 13.5 Tb.). The only change made to the machine was the transition from flat apertured plates, which protrude sharply from the inner surface 60 of the shell 12 and have no channels parallel to the inner surface, to the specially shaped apertured plates such as they are shown in FIGS. 6 and 7.

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The flat, apertured plates turned to steam

fed at about 4.25 kgf / cm to the inside of the edge ice 12 to dry the paper and there was a pressure difference of about 1.75 kp / cm. (As shown by Kessungen on the pressure gauges 32 and 48 results) is required to remove the condensate. With slightly larger prints, this became practically impossible Remove condensate as quickly as it has formed, which resulted in a thicker layer of condensate on the the jacket 12 forms a margin until the thickness has become greater than the distance between the jacket 12 and the drain pipes 34, which served as a shut-off device for the condensate P stream. This created cool zones on the outer surface of the jacket 12 and both the evenness and the drying speed were thereby disturbed. as the apertured plates 50 of Figures 6 and 7 in place of the flat apertured plates on the Downpipes 34 were attached, steam of about 6.5 was entered into the interior of the jacket 12 and there was a pressure

difference of only one kp / cm is sufficient to remove the condensate even if more condensate has formed. The condensate was kept at a uniform height of 0.2 cm. This resulted in a uniform, rapid and very effective Drying at elevated temperature whereby less energy was required to remove the condensate, resulting in a considerable amount of energy Energy cost savings resulted. It is thereby possible that paper machines with greater operating speed correct drying of a fabric work, even if in these attempts the speed of the drying cylinder was kept the same. There was also a reduction in the load on the device because hot air was used to dry the outside of the fabric.

The device according to Figures 3 to 5 was used in another drying cylinder of another paper machine, so that the resulting tests are not fully comparable. Jedooh can the drying cylinder with this device with a

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Working pressure of about 9 kp / cm, with only one pressure difference

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of about 0.3 kp / cm is necessary to remove the condensate.

This results in an even greater degree of efficiency and an even greater economic efficiency when removing the condensate than with the device according to FIGS. 6 and 7 and at the same time the paper machine can operate at a higher operating speed work, resulting in an improvement in the efficiency and economy in the operation of the entire machine leads. - ■ -.

Ea are of course various modifications of the device possible. For example, differently shaped with orifice plates and drainage pipes can be used. The form used will depend in part on the size and working conditions of the particular drying cylinder by using the device is used.

ORIGINAL BATHROOM 109808 / U70

Claims (12)

Patent claims Method for removing a condensate, which acts as an edge seated on the inner surface of the shell of a drying drum, the shell being under pressure in its hollow interior Can absorb steam, whereby the dumbbell is heated to dry the material running on the surface of the unfan ^ s, which leads to the Formation οϊ: ϊϊ3 condensate leads inside the jacket, and at The condensate is discharged by the steam through several openings into a discharge pipe in the flange and out of the jacket is carried out, with the openings adjacent to the inner surface of the jacket are provided and move with it, characterized in that that the steam flow is guided over a considerable distance along the surface of the condensate in the jacket (12), and that a pressure gradient is applied to the steam so that it has a sufficiently high velocity as it approaches the openings (52) receives so that it can take water from the inner surface of the jacket (12) so that water is entrained in the steam when the steam flows through the opening (52). 2. The method according to claim 1, ^ characterized by ™ that the steam is steadily accelerated as it approaches the openings (52) approaches, in that gradually the cross-section of the channels (56) through which the steam flows is reduced. 3. The method according to claim 2, characterized, that the steam with the entrained water is further accelerated when it flows out of the discharge pipe (34). BATH ORIGINAL 109808 / U70 4. The method according to any one of the preceding claims, characterized, that the steam flow to the openings (52) along the surface of the condensate in the jacket (12) over a distance on the order of 1.25 cm, and that the pressure gradient that is supplied to the steam, the steam one there is sufficient speed when it approaches the openings (52) that the surface of the condensate is with it moves at a speed of at least 4.5 m / sec, and that the condensate is thereby entrained in the steam when the steam emerges from the openings. 5. Device for removing condensate from a drying drum by a method according to one of the preceding Expectations, characterized, that a discharge pipe (34) is arranged in the jacket (12) and extends essentially over the entire length of the jacket and is in communication with the outside of the jacket, that the discharge pipe (34) with the interior of the jacket (12) through a plurality of openings (52) for Plüssigkeitsdurchlaß in conjunction that are arranged along the exhaust pipe near the inner surface of the shell at a certain distance, and to rotate therewith, that the device condensation ä sat in the vapor into the openings from the interior of the shell enters, and that Pührungsvorrichtungen (56) are provided which form elongated discharge channels for the steam, wad which run for a considerable distance substantially parallel to the inner surface of the shell (12) and are arranged under corresponding openings, whereby the Steam moving from the interior of the shell to the openings (52) moves along the surface of the condensate, so that water ■ from the inner surface of the shell sheared off and is entrained in the steam when it flows out through the openings (52). 109808/1470 -H- 6. Apparatus according to claim 5, characterized, that the discharge channels (56) parallel to the inner surface of the shell (12) over a distance of 1.25 cm to 10 cm of run out of the corresponding openings. 7. Apparatus according to claim 5 or 6, characterized in that that the guide device has a plate which is attached to the Downpipe (34) is attached and its outer wall next to the inner surface of the jacket to delimit the elongated drainage channels (56) is used. 8. Device according to one of claims 5 to 7, characterized, that the width of each channel flows through in the direction of de3 Current reduced. 9. Apparatus according to claim 8, characterized in that the height of each channel decreases in the direction of the flowing stream. 10. Device for removing condensate from a drying drum shell according to a method according to one of claims 1 to 4, characterized in that a discharge pipe (34) is fixed in the jacket (12) and rotates with it and extends over its entire length, which the discharge pipe (34) with the interior of the jacket (12) through several openings (52) for Liquid passage is in communication, which are arranged over the length of the passage tube adjacent to the inner surface of the jacket, that the drainage pipe (34) with the exterior of the jacket through a plurality of outlets (64, 40) for the passage of liquid in communication, that the Device condensates in the steam entering the openings (52) from inside the ridge ice and through the outlets (64,40) 109808 / U70 - 1 ϊ,. exits, .citreiSen, and that a guide device 3änjvJLicue defines outflow channels (pG) for the steam, which essentially run parallel to the inner surface of the liantel (12) over a considerable length and are arranged under corresponding openings (52), the wuersciuiitta surface of the drainage channels in the direction of the Datnpf-Btrön; ur.ö su der. corresponding openings, whereby the lair, which is moved from the inside to the dumbbell, is accelerated along the upper surface of the condensate, so that water is sheared from the inner surface of the dumbbell (12), and in the steam when it passes through the openings in the discharge pipe (34) is entrained. { 11. Performing according to claim 10, characterized, that in each case a channel (56) vcn the two perpendicular to the Ableitrchr (34) standing directions to each of the openings runs and that these channels in; essentially parallel to run flat surface of the Kanteis. 12. Performing according to claim 10, characterized, that an inlet pipe protrudes from each of the openings (52) into the discharge pipe (34), that an outlet pipe (64) protrudes from each of the outlets to the outside of the discharge pipe (34),. "since the inner ignition of each Zinlaßrchres is further inwards than the outer end of the Auslaßrchre, and that the cross-sectional area of all inlet pipes is larger and the cross-sectional area of all outlet pipes, whereby the steam leaves the discharge pipe (34) with greater speed than it enters it, thus a Hitreißen the condensate ensured in the steam let when the Danpf leaves the discharge pipe. - Rei / diK 109808 / U70 ORIGINAL BATHROOM Blank page