FI129327B - Arrangement for making removal of by-products more efficient in gas circulation of cable vulcanisation process - Google Patents

Abstract

An arrangement for streamlining the removal of by-products in gas circulation by the vulcanization process of cable, which process comprises a certain part of a vulcanization pipe between an inlet connection and a drain connection of gas and a recycling pipe (7A) and on this functioning recycling means between said drain and inlet, is characterized in that the recovery pipe (7A) comprises one or more devices (12A) wherein the pipe (14) is added with a pipe piece (17) directed towards the gas stream with a smaller diameter than the inner diameter of the pipe, which pipe piece is connected (18) to its outlet end. the pipe (14) so that the connection blocks the space (CS) between the pipe and the piece of pipe to collect in the space (CS) debris moving forward with the gas flow substantially as a liquid film on the inner wall (15) of the pipe (14), and one on the area of the space placed in a controlled manner openable and closable device (20, 21, 22, 23) to remove collected debris. A significant advantage of the arrangement according to the invention is that the purification of the gas is intensified inside the circulation pipe without substantially disturbing its function and gas circulation. The solution reduces the load on the equipment working in the gas circulation, such as a pre-filter and a heat exchanger, and reduces the need for cleaning.

Description

ARRANGEMENT TO ENHANCE THE REMOVAL OF BY - PRODUCTS BY CABLE IN THE GAS CYCLES OF THE VULCANIZATION PROCESS ARRANGEMENT FOR THE EFFECTIVENESS OF BORTING PRODUCTS GASCIRKULATIONER AV VULKANISERINGSPROCESS AV KABLAR

FIELD OF THE INVENTION The invention relates to the arrangement of gas circuits in a cable vulcanization process and in particular to the removal of vulcanization by-products in gas circuits. The invention can be applied, for example, to vulcanization processes in cable production.

BACKGROUND OF THE INVENTION In the production of cables, a vulcanization line is usually equipped with several gas circuits intended to operate either continuously or as required. In addition to the actual vulcanization zone - gas circulation, there may be a so-called Entry Heat Treatment (EHT) circuit at the very beginning of the line around the cable at high temperature to cool the melt-pressed insulation, minimize runoff and support roundness. After the vulcanization zone, the line is followed by cooling, which can be done with either gas or water. If it is done with gas, then there is a separate gas circuit for it. If it is done with water, then the line can have - in addition to gas pre-cooling, which lowers the surface temperature of the cable and for which there is its own gas circulation.

The gas used in the vulcanization process as a shielding gas and a transmitter of pressure and heating and cooling is usually nitrogen. Especially in cooling cycles, gas volume flows are large, for example in the order of 300 - 400 m // h. In nitrogen vulcanization, the cable runs in a pressurized tube, where the heated gas and the radiant heat of the vulcanization tube keep the temperature of the cable at a certain level according to the process. The temperature of the gas circulating in the vulcanization zone is usually in the range of 200 to 400 ° C, but can be higher. The pressurization N is required, inter alia, to prevent bubbling of the decomposition products from the vulcanization, and the normal gas pressure T is about 10 bar. The temperature of the nitrogen gas introduced into the cooling circuit is N 30 - again, for example, in the order of 25 ° C. E In addition to heat treatment and pressurization, vulcanisation is also a chemical process that generates gaseous, liquefiable and solid by-products, ie vulcanisation waste, which mixes with the circulating gas S and accumulates at a rapid rate in the vulcanisation and cooling pipeline. N 35 The most advantageous in gas cleaning are solutions in which waste is removed from the gas in arrangements belonging to the gas circulation itself. WO 2016189184 A1 discloses a solution

in which a gas cleaning and waste disposal arrangement is added to the central heat exchanger in gas recirculation. The purification of the gas has been further intensified by adding a pre-filter to the gas circuit, through which the gas enters the heat exchanger and where waste is removed from it. Even after pre-filtration and cleaning in a heat exchanger, by-products remain in the recirculated gas, especially in the form of light small droplets, which over time accumulate on the inner surface of the circulating piping and, finally, on the surface of the cable. It would therefore be desirable for the removal of by-products in the gas cycles of the vulcanization process to be further enhanced and improved. SUMMARY OF THE INVENTION It is an object of the invention to provide an arrangement for enhancing the removal of by-products in the gas cycles of a cable vulcanization process. To achieve this, the arrangement according to the invention for enhancing the removal of by-products in the gas circuit of a cable vulcanization process comprising a certain part - a vulcanization pipe between the inlet and outlet and recirculation pipe 1 in the characteristic part. Other claims define various embodiments of the invention. A significant advantage of the arrangement according to the invention is that the purification of the gas inside the circulation pipe is intensified without substantially disturbing the circulation of the gas and its operation. The solution reduces the load on the gas cycle equipment, such as the pre-filter and the heat exchanger, and reduces the need for cleaning. When the gas circulation equipment and pipes also have to be taken out of service at certain intervals for a special cleaning process, the need for cleaning can be reduced and the intervals can be extended by using the solutions according to the invention.

BRIEF DESCRIPTION OF THE DRAWINGS N The invention will now be described in more detail with reference to the accompanying drawings, in which: Figure 1 shows schematically the use of a solution according to the invention in N 30 Figures 3 to 7 show examples of implementations of the solution according to the invention in a gas recirculation pipe.

DETAILED DESCRIPTION OF THE INVENTION Figures 1 and 2 schematically show two possible gas circuits at the end of the vulcanization process. The cable 2 to be vulcanized comes from the vulcanization zone 1A of the production pipe to the rest 1B as indicated by the arrow C, where the cable is cooled and from where it passes through the line termination end 3 for finishing and storage. Nitrogen gas is fed to the vulcanization gas circuits from the tank 4 via a pipe 5 provided with a valve arrangement 6. It is not necessary to describe the equipment 8 required to control the gas recycling system in more detail here, nor to the water circuit WC, in which the actual cooling is performed in the example of Fig. 2.

In the gas circuit of Figure 1, the cable is cooled with gas by a pipe section 1B into which it comes from the joint A1 and flows around the incoming cable as indicated by the arrow G, cooling it. The gas, which is considerably heated and collects the vulcanization waste, is directed from the joint A2 to the recycle pipe 7A for treatment for a new cooling circuit. In the recirculation, the pre-filter 9, which cleans and removes the vulcanization by-products from the gas, can be, for example, as described in WO 2016189184 A1. The recirculation is then followed by a heat exchanger 10 in which the gas is cooled back to a temperature of, for example, 25 ° C. The heat exchanger is also combined with gas cleaning and removal, for example as described in the above-mentioned publication. After the heat exchanger, the fan 11 feeds the gas forward at the desired flow rate and through A1 back to the pipe 1B to cool the cable.

However, the pre-filter 9 and the cleaning arrangement operating in the heat exchanger 10 are not able to completely purify the gas from the vulcanization by-products. In particular, small light droplets remain in the gas, which are efficiently transported forward, especially by the very strong gas flow in the cooling circuit. Drops gradually accumulate on the inner surface of the tube, and a liquid film begins to form - which, as it thickens, begins to carry it forward. The purpose of the solutions according to the invention is to provide the recirculation pipes with arrangements by which the resulting wet film and waste liquid can be removed from the pipe efficiently while the disturbance of the gas circulation itself is kept to a minimum. The arrangements are also combined with solutions that - at the same time enhance the dripping and condensation of gas-borne by-products in the N 30 - liquid film to be collected.

E In the gas circuit of Fig. 1, the arrangement 12A according to the invention is in the recirculation pipe 7A shortly before the connection A1 and the gas enters the cooling pipe 1B, and the second arrangement 12B according to the invention

In the example of Fig. 2, where the actual cooling is performed by a water circuit, the recirculation pipe 7B brings the precooling gas from the B1 end to the end of the vulcanization pipe 1A and from the B2 back to the recirculation pipe 7B before further water cooling.

The arrangements according to the invention are also placed in the recycling pipe, respectively.

The arrangement 12A is in the recirculation pipe 7B shortly before the connection B1 and the gas entering the vulcanization pipe 1A, and the second arrangement 12B after the gas has returned from the recirculation pipe 7B to the pre-filter 9 and the pre-filter 9 is approached. said EHT cycle or some other gas cycle developed for the cable vulcanization process in which the use of the solution works and is useful.

Figures 3 and 4 show an example of the implementation of the arrangement according to the invention in a pipe section 14 connected to a recirculation pipe 7A, which is connected at both ends (only one end shown here) as part of the recirculation pipe 7A by respective flanges 16A and 16B.

The diameter of the pipe sections is, for example, 125 mm.

The gas flows in the direction of the arrow G.

Attached between the flanges 16A and 16B is a flange ring 18 facing the pipe section 14 and a pipe section 17 extending against the gas flow, also referred to herein as an inner pipe, having a length of, for example, 200-250 mm and a diameter of about 100 mm.

As a liquid film in the inner surface 15 of the pipe, the waste flowing with the flow now accumulates in the intermediate space CS of the pipes, where it is removed from the joint 20 through the pipe 21 and the valve 22 to a waste tank or the like 17 at the starting end.

The inner tube is dimensioned according to its purpose so that the length and volume of the intermediate space CS are sufficient and suitable for collecting liquid waste.

The diameter of the inner tube can be, for example, 70 to 90% of the diameter of the tube itself and the length, for example, 2 to 3 times the diameter of the tube.

The accumulated liquid is removed through the waste disposal arrangement 13 either by continuous small spillage or by intermittent blowing.

Similar waste disposal arrangements are found in the gas recirculation not only in the arrangements according to the invention but also in the precleaner 9 and the heat exchanger 10, and are shown schematically in Figures 1 and 2 by the same drawings and reference numeral 13. In the arrangement according to the invention in section 3 as indicated by the arrows G1, and if the flow rate is, for example, 350 m / h, the flow rate of the gas N 30 increases at this point from about 7 m / min to about 10 m / min.

In particular, a very sudden change in velocity E can cause flow disturbances or suction that separates droplets from the fluid film according to the flow.

To prevent this, it is preferred that the inner surfaces 15 ~ of the tube be smooth.

The jagged inner surface facilitates the dripping and transport of the liquid film with the gas.

The arrangement according to Figure 3 is preferably located on the vertical portion of the recycling tube.

The downward flow of gas facilitates the passage of liquid into the intermediate space CS of the pipes.

The arrangement can also be placed on the horizontal portion of the tube, in which case it is advantageous to bevel the end 19 of the inner tube 17A at an angle of, for example, 15 to 30 degrees as shown in Fig. 5. In this way, the change in the gas flow rate is mitigated and its possible effect on the dripping and migration of the liquid film according to the gas is mitigated. The inner tube 17A may also be a convex portion 24 of the outlet end flange plate 18 for narrowing the intermediate space CS of the tubes in the flow direction.

Figure 6 shows another solution to alleviate the sudden change in gas flow rate and its possible effect on liquid dripping and migration according to the gas flow. The inner tube 17 is extended by a perforated plate tube 29 which fits over it and overlaps in part, which extends the length of the inner tube to, for example, about 400 millimeters. The solution alleviates, on the one hand, the increase in the gas flow rate so that it takes place in the inner tube gradually in the region of the perforated plate tube, and, on the other hand, the slowing of the movement of the liquid film as it enters the intermediate space. This additional solution is especially useful when the pipe and gas flow are directed downwards.

Referring to Figures 3 to 6, various embodiments of the arrangement 12A of Figures 1 and 2 according to the invention are shown. Figure 7 shows a simplified embodiment 12B of an arrangement according to the invention. A water cooling jacket 26 is added to the recirculation pipe section 14 provided with the inner pipe 17 according to the invention. When the pipe 14 is 125 mm in diameter, the jacket 26 is formed by a surrounding pipe section 26 attached, for example, by welding the outer surface of the tube 14 to close the jacket. Water enters the jacket from joint 28A and leaves joint 28B. The unit 29 is intended, for example, for emptying and rinsing the diaper if necessary.

Inside the jacket, for example, there are flow control arrangements at the ends and in the vicinity of them and the water connections, for example rings which direct the flow of water more evenly into the jacket. The cooling jacket 26 operates in the region of the gas flow to the inner tube 17 of the arrangement and the N part of the inner tube, and is intended to enhance the dripping, condensation and integration of the waste accompanying the flow N into the inner surface of the tube. .

E When the use of a cooling jacket is substantially useful in the arrangement according to the invention, for example in the treatment of gas heated in cooling, the arrangements ~ 12B provided with it are arranged to act as gas precoolers before the pre-filters 9 in the examples.

The implementation of the arrangement according to the invention is not limited to the above examples. The design, placement, and dimensions of the inner tube, as well as the other arrangements associated with it, can vary in many ways in practice. The invention may vary within the limits allowed by the appended claims.

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Claims (6)

PATENT REQUIREMENTS Arrangement for streamlining the removal of by-products in gas circulation by the vulcanization process of cable, which process comprises a specific part of a vulcanization pipe (1B, 1A; 1A) between an inlet connection (A1, B1) and a drain connection (A2, B2) of gas and a recycling pipe (7A, 7B) and on this functioning recycling means (9, 10, 11) between said drain and inlet connections, characterized in that the recycling pipe (7A, 7B) comprises one or more devices (12A, 12B) wherein the pipe (14) is added with: a pipe piece (17, 17A) directed towards the gas stream with a smaller diameter than the inner diameter of the pipe, which pipe piece is connected (18, 24) to the pipe (14) at its outlet end so that the connection blocks the space (CS ) between the pipe and the piece of pipe to collect in the space (CS) debris moving forward with the gas flow substantially as a liquid film on the inner wall (15) of the pipe (14), and an opening in the area of the space (CS) in a controlled manner and closing ba r device (20, 21, 22, 23) for removing collected debris. Arrangement according to claim 1, characterized in that the diameter of said piece of pipe (17, 17A) is 70 - 90% of the diameter of the pipe (14). Arrangement according to claim 1, characterized in that the length of said piece of pipe (17, 17A) is 2-3 times the diameter of the pipe (14). Arrangement according to claim 1, characterized in that said pipe piece (17A) is shaped so that its open end (19) is chamfered with respect to the direction of the pipe piece to mitigate change - of flow rate of gas. N Arrangement according to claim 1, characterized in that said pipe piece (17) is extended by. a perforated tube (29), which fits on and partially overlaps it to soften one side <? change in flow rate of gas and on the other hand slowing down the movement of the liquid film. N 30 E Arrangement according to claim 1, characterized in that the pipe (14) is provided with a cooling water jacket (26, 27, 28A, 28B, 29) acting on it in the area before the pipe piece (17) and partly in S its area with the purpose of improving droplet formation, condensation and accumulation in the surface stream of the vulcanizing debris accumulated in the heated gas just before the device for stopping, collecting and removing said debris from the pipe.