DE2552746A1 - Vacuum drier for condenser and transformer cores - has heater to revaporise working fluid in thin film to separate contaminants - Google Patents

Abstract

Condenser and transformer cores re heated for drying and de-gassing by allowing kerosene vapour to condenser on them in a vacuum chamber. The condensed kerosene dissolves oil which is present in the condensers etc., and becomes contaminated by it. To remove the oil and revapourise the kerosene a heater is in the form of a plate over which the contaminated liquid would pass in a thin film. The plate temp. would be high enough to evaporate the kerosene for re-cycling and the oil would flow down into a sump from which it would be emptied at intervals.

Description

Arthur Pfeiffer Vacuum Technology Wetzlar GmbH

Asslar

Use of a thin film evaporator for condensation Aufhe i ζ plants.

The invention relates to a system for heating parts such. B. Transformers and their cores as well as capacitors, for the purpose of drying and degassing under vacuum.

There are various methods by which parts that are to be dried in a vacuum are brought to the desired temperature will. The present invention relates to the condensation-heating process (vapor phase process).

The parts to be dried - these are essentially the paper-insulated cores of transformers and capacitors - are located in a vacuum-tight chamber or in their own vacuum-tight housing. To heat the parts on the required drying temperature is the vapor of a low-boiling liquid, e.g. B. Kerosene, let into the chamber. When this vapor condenses on the even colder surfaces of the parts, the heat of condensation that is released is released this over and increases its temperature. The draining condensate dissolves the residues of oils adhering to the parts, which are considerable, especially in the case of transformers that have already been used Quantities can occur. For reuse, the liquid is collected and transferred to an evaporator by means of a feed pump fed. For better drying and for safety reasons, the whole thing takes place under vacuum at pressures between 200 and 1 mbar instead. This procedure is well known. It is also known that for the evaporation of the low-boiling liquids Conventional heat exchangers, e.g. B. Tube evaporator ver · »· be turned. These bring the disadvantage; that the high-boiling components of the coming to evaporation Mixture remain in the evaporator and due to the higher concentration the evaporator performance decreases rapidly with the consequence

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increased heat consumption and longer heating times. Furthermore have to clean the evaporator and to separate the low-boiling liquid from oils at short intervals blank batches driven, which cause further losses.

A method is also known in which the separation of low-boiling and high-boiling parts is carried out by that the liquid is superheated and under pressure through a nozzle into the drying chamber in which the parts are located, injected and expanded. The low-boiling parts evaporate then, whereby the steam temperature is reduced so that the to be dried by the heat of evaporation consumed Parts are no longer damaged by the excessive temperature. The high-boiling components of the liquid evaporate not and are fed to a collecting vessel through suitable baffle plates or the like. In the event that the The parts to be dried are transformers in their own housing, this expansion evaporation is also in an upstream Expansion vessel, which is connected to a collecting vessel for the high-boiling components, carried out. This process has disadvantages of higher equipment and control engineering costs.

The invention has set itself the task of those described here To eliminate disadvantages and in a process-technically simple way a continuous'ürnung the easy- and to carry out high-boiling components of the contaminated heating fluid.

The solution to the problem is that for the evaporation of the low-boiling heating fluid and the separation of the vapor For the same of the high-boiling constituents, a thin-film evaporator known per se is used. Such a thin-film evaporator are designed so that the heated surfaces in the evaporation kettle are covered by a thin film of the Liquid are wetted, the temperature of the same can be kept so that only the component of the Liquid evaporates, the evaporation of which is desired, while the parts that should not evaporate on the walls flow along, are led into a collecting container and there-

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be separated from the liquid to be evaporated. This has the advantage that it is inside the evaporator there is no high concentration of high-boiling fractions and thus good heat transfer and continuous heat transfer constant output of steam for heating the parts is guaranteed.

The invention is illustrated below using a flow chart, for example described in more detail:

The parts 2 are located in a drying kettle 1. From the thin-film evaporator 3, kerosene vapor is introduced into the drying kettle via a line 5. The steam condenses on the surfaces of the parts 2 and gives off its heat of condensation to the parts. The condensate collects at the bottom of the drying kettle 1 and is returned to the evaporator via a feed pump 6. In the lower part of the evaporator there is a collecting container h in which the oil collects and from where it can be drawn off either during breaks in operation or continuously during operation. The vacuum in the drying vessel 1 is produced and maintained by a vacuum pump 8 with an upstream condenser 7 and condensate collecting vessel 9 for the heating liquid. If there is a larger amount of water vapor, another condenser is interposed to keep the water away from the vacuum pump.

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Claims (1)

System for heating parts under vacuum by the heat of condensation of the vapor of a first liquid, e.g. B. to
Purpose of drying and / or degassing, with at least one second higher-boiling point from the parts during the heating
Liquid accumulates which mixes with the first liquid condensed on the parts and is flowing off and is fed back to the evaporator, consisting of an evacuable tank, a vacuum pump, at least one steam condenser between the tank and the vacuum pump and a steam generator connected to the tank, characterized in that, that the
Steam generator is designed as a thin-film evaporator and a vessel is arranged under the evaporator, in which the non-evaporated and / or higher-boiling components
of the liquid mixture are collected. 709821/0553 ORtGiMAL INSPECTED