HK1091026B - Air de-humidifier for oil-insulated transformers, choke coils and step switches - Google Patents

Description

The invention relates to an air dehumidifier used as an accessory in oil-insulated transformers, throttle coils or step switches to dehumidify the air sucked into oil-extraction vessels.

A dehumidifier of this type is already known from the JP 60198710 A1. It has two identically constructed filter chambers, each filled with a moisture-absorbing material. From the bottom, through a bell arrangement with an oil sink, the sucked air flows through at least one of the two filter chambers, where the moisture-absorbing material passes through, is dried and leaves the dehumidifier upwards. In addition, an electric heating device is provided in each of the two filter chambers. When the moisture-absorbing capacity of the top absorber material in the respective filter chamber is exhausted, the corresponding heating device is inserted, thus heating and drying the hot material.

The European patent application EP 1313112 A1 proposes a further developed dehumidifier. The dehumidifier is mounted in the stream of dried air, after it has passed through the actual filter insert filled with moisture-absorbing material, a moisture sensor, which, depending on the condition, activates the heating inside the filter insert. The moisture sensor detects the moisture state of the air flowing around it, which should have already been dried. If the moisture sensor signals that the moisture in this sucked air exceeds a certain limit, thus heating up to the bottom, this means that the previously dried material has been absorbed, no further moisture is absorbed and the filter must be heated.

A further dehumidifier is given in DE 3413071 A.

However, it has now been shown that in the case of the known dehumidifiers in practical operation, the heated liquid cannot be removed through the outlet openings above the heater or completely drained downwards. Rather, some of this heated liquid settles on the cylindrical inner wall of the filter chamber or the housing wall of the dehumidifier in the form of fine droplets. These fine droplets of water remain there, due to their surface tension, and cannot be removed. This is undesirable because over time this constantly increases the moisture concentration in the area of the heating equipment.

The purpose of the invention is therefore to eliminate the disadvantages of the present state of the art described and to specify an air dehumidifier of the above-mentioned type which, by means of special measures, ensures that the liquid heated by the operation of a heating device made of a moisture-absorbing, regenerating filter material actually leaves the filter assembly.

This task is solved by an air dehumidifier with the characteristics of the first patent claim.

The main advantage of the invention is that the special design of the ground part according to the invention achieves a defined, locally limited dew point crossing inside the filter system, which then results in a targeted condensation of the heated liquid at this ground part, and the defined and locally limited condensed liquid flows safely from there.

The invention is explained in more detail below by means of illustrations.

It shows: Figure 1a complete dehumidifier according to the invention in a lateral, schematically-intersected representationFigure 2excerpted from the bottom area alone with a floor part according to the inventionFigure 3the view of a floor part alone of a further developed dehumidifier according to the invention from belowFigures 4 - 6different lateral intersections of the floor part shown in Figure 3.

The dehumidifier has a floor part 1 in which a ring seal 2 is inserted, on which a cylinder 3 rests. Upwards the cylinder 3 is closed by a lid 4; here again a ring seal 5 is provided for sealing. For attachment vertical support rods 6 are provided with rim nuts 6.1 screwed through below, outside the floor part 1. Above, screws 7 are provided as sealing agents.The heating elements are located between the granulate 9, i.e. enclosed by it. The granulate 9 is not shown here in detail for the sake of clarity. Above the lid 4 there is a magnetic valve 12, above the magnetic valve 12 there is a lower flange 13, to which an upper flange 14 is attached. Between the upper flange 14 and a lid 15 there is another housing 16.The volume of the oil sample 21 is limited by the inner wall, which is shaped like a tulip. 19 Between the lower flange 13 and the upper flange 14 there is a further ring seal. 22 Between the upper flange 14 and the housing 16 there is a ring seal. 23 And between the housing 16 and the lid 15 there is a ring seal. 24 Above the lid 15 there is a tube flange. 25 It is again secured by eye screws. 26 and wing nuts.as explained above, the humidity of the air circulating in it. If the recorded humidity exceeds a pre-set limit, this means that the granulate 9 is at least largely saturated, no further moisture is absorbed and drying is necessary. In this case, the electrical circuit of the heater 10 is closed in the control case 28 by unspecified switches. At the same time, the magnetic valve 12 is also closed. Now, the heater 10 heats the granulate 9 and thus dries it.Finally, the switch housing has 28 additional bolts 31 for connecting electrical connecting wires and a power supply, which are also not shown.

Figure 2 shows the lower part of the dehumidifier in order to better illustrate the floor part 1 of the invention. The floor part 1 is made of metal, is relatively thick and has a good specific heat conduction. The inner contour 1.1 is formed in the form of a funnel; at the lowest point of the funnel in the middle there is an opening 1.2. Through this opening 1.2 the sucked and still too dry air enters the cylinders 3 and then into the air permeable housing 8, through which the Granrock 9 is passed and condensed. Through the opening 1.2 the same heated liquid that is condensed at the interior contour 1.1 enters downwards. This specific design of the floor part 1 is made of a good insulating material and thus achieves a locally defined and limited function of the moisture in the interior 1.1 and thus achieves the specified function of conducting the heat and humidity.

To support the effect described, it is particularly advantageous to make cylinder 3 from a material with poor specific thermal conductivity.

A further feature of the invention is that a lower rounding 1.4 is provided on the inner contour 1.1 to avoid sharp transitions throughout the inner contour 1.1, thus facilitating the desired complete flow of the liquid condensed there. Finally, a screw 32 is shown in Figure 2 which is arranged downwards in the opening 1.2 and which will be discussed in more detail below.

In Figures 3 to 6, another floor component 1 of the invention is shown alone, and this floor component 1 has special features which are described in more detail below.

Screw 32 has a sieve 33 in this case, which ensures that no dirt particles or other foreign matter can enter the interior of the dehumidifier through the inhaled air or otherwise, for example, the sieve 33 may be made of sintered bronze, which provides additional noise reduction in addition to the filtering effect described.

In general, such a sieve 33 does not prevent the dripping of the heated liquid downwards. However, under certain climatic conditions, at low temperatures, there may be a risk of icing this area. Therefore, in many cases it may be advantageous to provide additional heating of the floor part 1 of the dehumidifier of the invention. To this end, a ring-shaped outlet 34 is provided in floor part 1 from which a radial thread 35 leads outwards. In the outlet 34 an electric heater 36 is placed. An electric resistance heater 36 is particularly advantageous. The electrical connections 37 of the heating lines are through the 36 fabric holes 35 and 38 cable wires are wired in it to the outside.The outer connection downwards is formed by a cover flap 40 which has a central flange-shaped dustproof 41 which encloses and protects the screw 32. The cover flap 40 is secured by screws 42, 43 which are screwed into threads 44, 45 in floor 1. Furthermore, floor 1 has vertical through-hole holes 46, 47 which are used to accommodate the non-placed support bolts. These support bolts are described above in conjunction with Figure 1 and bear the reference sign 6.

Finally, in many cases it is useful to thermal decouple the heating of floor part 1 from the electric heater 36 in order to ensure that only the surroundings of the bolt 32 are heated as desired. In other words, the electric heater 36 is to operate only where there is a real risk of icing. To achieve this thermal decouplement, a first insulation pane 48 is provided between floor part 1, electric heater 36 and floor flange 39 and a second insulation pane 49 between floor part 1 and floor flange 39. The insulation panes 48, 49 are made of, for example, Teflon and thus prevent heating of the remaining parts of the air-conditioning unit.

Claims (8)

1. Air dehumidifier for oil-filled transformers, choke coils and tap changers, for dehumidification of air sucked into oil expansion vessels, comprising a cylinder (3) which is closed at the top by a lid (4) and at the bottom by a base part (1), an air-permeable housing (8) arranged within the cylinder (3) and filled with a moisture-absorbing granulate (9), wherein a space which is filled by the inducted air after this has flowed through the granulate (9) in the housing (8) is present between outer wall of the housing (8) and inner wall of the cylinder (3), an electrical heating device (10) in the interior of the housing (8) and a moisture sensor (29) which is arranged in the space between outer wall of the housing (8) and inner wall of the cylinder (3) and by which the heating means (10) is activatable when the limit value of the measured air humidity is exceeded, characterised in that a base part (1) of metal or another material with a good specific thermal conductivity is provided, the inner contour (1.1) is formed to be funnel-shaped, and that the funnel-shaped inner contour (1.1) has a lower radiusing (1.4).
2. Air dehumidifier according to claim 1, characterised in that the cylinder (3) consists of a material with a worse specific thermal conductivity than that of the base part (1).
3. Air dehumidifier according to claim 1 or 2, characterised in that a screw connection (32) with a water-permeable filter insert (33) is provided centrally at the deepest position in the base part (1).
4. Air dehumidifier according to claim 3, characterised in that the filter insert (33) consists of sintered bronze.
5. Air dehumidifier according to claim 3 or 4, characterised in that a further heating means (36) is provided in a circular cut-out (34) accessible from below and surrounding the screw connection (32).
6. Air dehumidifier according to claim 5, characterised in that the further heating means (36) is an electrical resistance heater, the electrical connecting lines (37) of which are led through a cable screw connection (38) radially screwed into the base part (1).
7. Air dehumidifier according to claim 5 or 6, characterised in that the heating means (36) is thermally decoupled from the base part (1) by at least one insulating washer (48, 49).
8. Air dehumidifier according to claim 5, 6 or 7, characterised in that the cut-out (34) is closed downwardly by a base flange (39) and/or a cover flange (40), which is fastened to the base part (1) by means of screws (42, 43).