DE9404428U1 - Solar sterilizer - Google Patents

Description

Solar sterilizer *

The invention relates to a solar sterilizer. This can be designed for use in crisis and disaster areas as well as for permanent use in stationary medical stations and field hospitals.
The object of the invention is to create an easy-to-use solar sterilizer in which the heat energy generated by solar radiation in the collector is transferred to the fluid to be boiled with as little loss as possible.

This object is achieved, according to the invention, in a solar sterilizer with a coupled collector for heating the fluid with a manually controlled control unit and control fittings. The collector is connected to the sterilization chamber by a flexible connection in such a way that the increase in pressure when the fluid boils causes the vapor phase to enter the upper point of the chamber and gravimetrically displace the air via the air and steam outlet located at the lower point.

This procedure replaces the otherwise necessary and very time-consuming evacuation of the sterilization chamber,

Distilled or demineralized water is preferably used as the fluid, which prevents the formation of scale inside the absorber tubes,
Natural stones are used in the oil storage tank to store heat. High-boiling natural oil such as peanut oil is used as a heat exchanger. Natural oils are non-toxic, ecologically harmless and are available in almost unlimited quantities. The resulting stone-oil filling of the heat storage tank leads to a stable temperature stratification even during charging. When discharging and the associated heating of the distilled or demineralized water, this leads to high heat flows and thus short heating-up times, even when the storage tank is not fully charged. Both the sterilization chamber and the opaque surfaces of the collector and the heat storage tank are well insulated to prevent heat loss. The thermal expansion vessel of the stone-oil storage tank is thermodynamically decoupled. The heat storage circuit is operated without pressure and runs free of additional energy through thermosiphonic flow. The heating medium gives off part of its energy in the heat storage tank and flows back to the absorber through the oil return. A backflow preventer prevents a reversal of the thermosyphonic flow and the associated discharge of the storage tank via the collector at times when the heat storage tank is not being charged via the collector.

Steam can be generated in a conventional heated boiler, e.g. with an electrical resistance heater or by a heat source located outside the boiler.

The invention is explained in more detail below using an exemplary embodiment. The drawings show schematically:

Fig. 1 Mobile sterilizer with flat collector

Fig. 2 Mobile sterilizer with concentrating collector

Fig. 3 Interior sterilizer with flat collector

Fig. 4 Interior sterilizer with flat collector and storage

In Fig. 1 and Fig. 3, the solar sterilizer with a flat collector (10), as well as the capillaries (6), the water tank (11) and the filling device (12) are shown schematically.

The fluid heated to the boiling point in the collector (10) flows as a vaporous phase into the sterilization chamber (3) equipped with an air and steam outlet (1), a safety valve (4), insulation (5) and a chamber door (2) and displaces the air gravimetrically. The air and steam outlet (1) is designed as a manually controllable control unit and enables the required operating pressure to be varied in addition to venting the sterilization chamber (3).
In the exemplary embodiment, the solar sterilizer is operated via a flexible line with an inclined flat collector (10). The collector has opaque insulation on the back and sides to suppress heat loss. A polycarbonate pane serves as the outer cover of the absorber. A UV-stable, heat-resistant film is attached between this polycarbonate pane and the absorber surface to keep convective heat loss to a minimum. This combination also leads to a reduction in weight and is mechanically stable. To absorb the solar radiation, a selectively coated absorber (7) is arranged below the transparent covers (9), whereby the mirrors (8) attached to both sides of the collector also reflect radiation onto the absorber and are folded up to protect the transparent cover (9), e.g. during transport.

Instead of the flat collector (10), a concentrating system (Fig. 2, 2a) can also be used, whereby the water tank (11) can be arranged both parallel (as shown in the embodiment) and transversely communicating with the absorber tubes.

As an interior sterilizer, the'Systeffi can be operated both with (see Fig. 4) and without a storage tank (see Fig. 3), whereby the heat input into the storage tank (18) and the heat output take place via an internal heat exchanger.
In the interior sterilizer with flat collector and storage tank (Fig. 4), the heating medium, if there is sufficient solar radiation, flows back into the absorber (7) through the resulting thermosiphonic flow via the oil return (19) after it has flowed through the oil storage tank (18) and released part of its thermal energy.

A non-return valve in the oil circuit prevents the flow direction from being reversed and the associated heat loss from the oil reservoir (18) via the collector (10) during the night or when the radiation is too low.

The sterilization chamber (3) holds the goods to be sterilized, whereby in the example the chamber size is adapted to a standardized sterile goods cassette according to DIN 58946. The solar sterilizer achieves the thermal resistance levels required by the "German Pharmacopoeia" (DAB 9/1986), which has been officially confirmed. The solar sterilizer can be designed in different dimensions and versions for the various areas of application. Steam can be generated directly via the collector (10), via the heat storage unit (18) or as a hybrid system with an external steam generator that is not powered by solar energy.

Legend:

1 Air and steam outlet 2 Chamber door 3 Sterilization chamber 4 Safety valve 5 insulation 6 capillary 7 absorber 8th Mirror 9 Transparent cover 10 collector 11 Water tank 12 Funnel with filling valve 13 bolt 14 Water level 15 Swivel base 16 wheel 17 Shut-off valve 18 Oil storage 19 Oil return

Claims (10)

SC'FTUTZAN-S'PRÜCH^ 1. Solar sterilizer with the functionality of an autoclave, whereby the connected solar collector (10) heats process water and the boiling fluid is guided into the sterilization chamber (3) in a controlled manner by the resulting pressure difference and via the air and steam outlet. 2. Solar sterilizer according to claim 1, characterized in that a chamber door (2), a safety valve (4) and a thermal insulation (5) are located on the sterilization chamber (3). 3. Solar sterilizer according to one of claims 1 or 2, characterized in that a manometer and a thermometer are installed in connection with the chamber interior. 4. Solar sterilizer according to one of claims 1, 2 or 3, characterized in that the steam inlet is located at the top and the air and steam outlet at the bottom of the chamber. 5. Solar sterilizer according to one of the preceding claims, characterized in that the connection between the sterilization chamber (3) and the collector (10) is formed by a detachable, flexible line. 6. Solar sterilizer according to one of the preceding claims, characterized in that the collector (10) is equipped with mirrors (8) for concentrating the solar radiation on the absorber (7) provided with a transparent cover (9). 7. Solar sterilizer according to one of the preceding claims, characterized in that the evaporated water quantity flows independently from a water tank (11). 8. Solar sterilizer according to one of the preceding claims, characterized in that the absorber (7) and the water tank (11) are arranged in communication and the pressure equalization takes place via a capillary (6). 9. Solar sterilizer according to one of the preceding claims, characterized in that the sterilization chamber can be coupled to a steam generator not operated with solar energy. 10. Solar sterilizer according to one of the preceding claims, characterized in that a heat accumulator (18) is integrated with an internal heat exchanger in such a way that the heating medium heated by the collector (10) flows through the heat accumulator (18) via natural convection and the discharge of the accumulator can be controlled via a control unit (17).