1. Title of the invention

Title of Invention: Adaptive Discrete Vented Enclosures System (ADVES) for hot chemical baths of Aerospace Industry.

2. Field of Invention

The present invention relates to thermal engineering in general and in particular to reduction of heat dissipation & hazardous fumes by employing Adaptive Discrete Vented Enclosures System (ADVES) for hot chemical baths iri Aerospace Industry.

3. Background of invention

Aerospace Industry involves various Heat/Chemical Treatments of large metallic components, which need large open containers as tanks with the desired chemical composition in fluid state. The top side of the bath is required to be open for loading, unloading of components as well as for venting of the fumes during the process.

Heat/Chemical Treatment Cycle is defined by the composition of the bath, temperature control (heating rate, soaking temperature, soaking duration & cooling rate) & durations of various stages of the cycle.

For some of the processes, a high temperature (as high as 90 to 100°C), is required to be maintained at uniform temperature value (within a range of ±5°C) for a certain duration, called soaking temperature period.

This High Temperature in the bath is achieved using Heat Generator System. Heat Generator is the heat source which heats the thermic fluid to a temperature significantly higher than the required bath temperature. Further, the thermic fluid flows in heat transfer pipes or lines routed inside the tank. High temperature thermic fluid inside the pipes transfers the heat to the lower temperature fluid inside the bath. This process is carried out till the desired uniform temperature is achieved in the bath, which is . measured using thermo-couples strategically located at different locations. Ideally, the bath temperature is required to be retained at the uniform temperature value throughout the tank within a predefined tolerance range (say ±5°C). Once, the desired temperature range is achieved, Heat Generator input is stopped to avoid further increase in the temperature of the bath.

However, due to the high temperatures, there is naturally a huge thermal gradient with reference to the room temperature. This huge difference in the temperatures of the system & surroundings result in natural vaporization of some of the constituents of the bath. Gradual loss of minor quantities of fumes is natural & desirable. If the tank is closed, fumes get trapped under the lid during the course of the process. During the unloading of the component, large amounts of fumes escape from the tank in a very short duration which results in level of hazardous fumes exceeding
Construction;

The current invention consists of a system of discrete hollow Spheroidal thermo-plastic polymer based enclosure entities with defined composition based on the selected set of chemical compositions & peak temperature requirements.

Spheroidal diameter, wall thickness, specific gravity and quantity of entities are designed based on the chemical composition of the bath, peak temperature requirement, size of the Heat/Chemical Treatment Tank.

The Spheroidal entities are manufactured by conventional gas injection molding process which is easy & cost-effective for mass-production.

These Spheroidal entities are designed to have specific gravity lighter than the bath chemicals resulting in floating on the top surface of the process solutions & hence the system acts as a vented - enclosure for reducing the heat dissipation as well as minimizing the escape of hazardous fumes from the solutions of Heat/Chemical Treatment Baths at high temperatures.

These Spheroidal entities are having single point contact with the Aerospace components during loading/unloading & processing, resulting in very low friction & significantly minimal wear/tear.

Function:

The excessive loss of fumes is restricted by employing the Adaptive Discrete Vented Enclosures System (ADVES), which covers a majority of top surface area.

Being discrete entities, they adapt to the motion of loading & unloading of the charge & no hindrance is observed. By virtue of the spheroidal shape of the enclosure element & designed size, a suitable restricted venting of the fumes is achieved.

The spheroidal entity is easy to manufacture, operate & maintain. The material selected is non-contaminating (for the selected set of chemical constituents) and thermally resistive (for the pre-defined peak temperature).

Due to the use of this system, the composition of the bath is observed to be maintained within the acceptable limits over a significantly longer duration of the operation. Hence, expensive calibrations & corrections of bath compositions are considerably reduced.

Current innovation resulted in reducing the temperatures drops by over 50%. Subsequently, requirement of heat input is considerably reduced (40% reduction of fuel quantity in per day consumption).

Thereby resulting in significant energy savings & cost savings in. operation as well as maintenance of Heat Generator System.

Name of the Applicant Hindustan Aeronautics Limited
acceptable levels. This phenomenon of excessive fumes in short duration can be fatal for the operators & surroundings. However, due to large sizes of the tanks. & huge thermal gradients, excessive loss of hazardous fumes is generally witnessed in Aerospace Industry.

Prior art:

a) Mechanical Closures of the Tank which can be opened or closed during loading & unloading of the large size components.

b) Soaking temperature is required to be maintained within ±5°C. However, due to large sizes & huge thermal gradients with surroundings, excessive heat losses are observed resulting in soaking temperature becoming 10 to 15 °C lower than the cycle requirement. To compensate this heat loss, excessive heating & intermittent heating are enforced to regain the necessary soaking temperature, which often results in process deviations from the defined cycles.

Drawbacks of Prior Art:

a) When Mechanical Closures are employed, excessive fumes, escape during loading/unloading, in a very short duration of time, which is highly hazardous & fatal to the operators as well as surroundings. Controlled venting & effluent treatment is very expensive for large size Aerospace baths with mechanical enclosures.

b) Excessive & Intermittent heating involves additional costs of fuel, maintenance & operation. Undesirable Process deviations are very likely to occur due to compensatory heating.

4. Summary of the present invention

Adaptive Discrete Vented Enclosures System (ADVES) for hot chemical baths, is an inventive solution to restrict the excessive loss of fumes in large size Heat/Chemical Treatment Tanks.

It consists of a discrete hollow spheroidal thermo-plastic polymer based enclosure entities with defined composition based on the selected set of chemical compositions & peak temperature requirements.

5. Brief description of drawings

FIG-l & FIG-2, illustrate the loading & unloading respectively for different charges, for the Adaptive Discrete Vented Enclosures System (ADVES) for Aerospace Hardware Components.

6. Detailed description of invention

Adaptive Discrete Vented Enclosures System (ADVES) for hot chemical baths is an inventive solution to restrict the excessive loss of fumes in large size Heat/Chemical Treatment Tanks.