Check valve

Abstract

A check valve which includes a body adapted at one end to receive a liquid source and at the other end to engage with a spray nozzle and having a bore therethrough, an internal annular recess within the body, the upstream end of which body provides a valve seat, a valve assembly located in the recess and having a valve member having a generally curved end directed towards the seat and bias means to normally hold the member against the seat until the pressure at the inlet reaches a predetermined minimum.

Description

AREA OF THE INVENTION[0001]This invention relates to a check valve which is specifically adapted to be used with spray drying nozzles, but could also be used in association with other nozzles.BACKGROUND TO THE INVENTION[0002]For ease of description, we shall refer to the valve when associated with spray drying of milk.[0003]Spray drying techniques are well known and in these milk is sprayed through nozzles into a chamber where the liquid part of the milk is evaporated away and milk powder either falls to the floor of the chamber and is removed therefrom.[0004]Historically, on completion of operation the spray drying industry simply stopped pumping the liquid through the nozzles and as the pressure dropped, a certain percentage of the liquid simply fell as drops from the nozzles, without being atomized, and this material could well lead to pollution of the product in the chamber.[0005]Check valves have been proposed but in practice have suffered from major disadvantages.[0006]A first...

AI Technical Summary

Benefits of technology

"The invention is a check valve for spray drying nozzles that allows liquid to flow through the nozzle without causing any restrictions. The valve has a curved end that forms a seal with the valve seat when closed. The valve is easily cleaned and can be interchanged without disturbing the system. The valve is located in a spray nozzle assembly and is designed to prevent leakage during the sealing phase. The valve member is guided and located within the valve body to allow fluid to flow around it. The valve is engaged with the spray nozzle using bayonet fittings or screw means. The valve cage is housed and guided within the valve body and can be easily removed. The valve can be used with different types of springs and sealing membranes. The invention provides a solution for preventing blockages and ensuring smooth operation during spray drying."

Problems solved by technology

Historically, on completion of operation the spray drying industry simply stopped pumping the liquid through the nozzles and as the pressure dropped, a certain percentage of the liquid simply fell as drops from the nozzles, without being atomized, and this material could well lead to pollution of the product in the chamber.

Check valves have been proposed but in practice have suffered from major disadvantages.

A first such disadvantage is that the valves caused a limitation in liquid flow therethrough and there was a large pressure drop over the valve.

The second disadvantage was that these valves normally had a soft seal, such as an O-ring and it was found, in practice, that this seal could be destroyed during use which would enable parts of the O-ring to pass to the chamber, again polluting the product.

In fact most of these check valves have had a complex design which requires the use of many seals and multiple sealing points.

As a result there are many stagnant points such that milk products can build up and, if overheated, catch fire.

Additionally soft seals are prone to failure and consequent leakage.

As such check valves are generally welded together any repairs are extremely difficult.

Other check valves have used metal to metal seals which increases the wear rate and as discussed above access for repair is difficult in conventional valves.

An additional disadvantage with previous check valves is that as fluid flow is not necessarily smooth through them and stagnant deposits can form they are difficult to keep clean.

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