Electrostatic spray dryer system

Abstract

An electrostatic spray dryer for drying liquid into powder including an elongated cylindrical drying chamber having an electrostatic spray nozzle at an upper end and a powder collection vessel at a lower end. The powder collection vessel includes a removable and replaceable filter collections sock made of filter material for receiving and collecting dried powder from the drying chamber. For cleaning residual powder from an inside wall of the drying chamber, a scraper member is provided that is coupled by magnetic attraction to a manually removable driver on the external surface of the wall.

Description

[0001]This patent application claims the benefit of U.S. Provisional Patent Application No. 62 / 754,691, filed Nov. 2, 2018, which is incorporated by reference.FIELD OF THE INVENTION[0002]The present invention relates generally to spray dryers, and more particularly to an apparatus and methods for spray drying liquids into dry powder form.BACKGROUND OF THE INVENTION[0003]Spray drying is a well known and extensively used process in which liquid slurries are sprayed into a drying chamber into which heated air is introduced for drying the liquid into powder. The slurry commonly includes a liquid, such as water, an ingredient, such as a food, flavor, or pharmaceutical, and a carrier. During the drying process, the liquid is driven off leaving the ingredient in powder form encapsulated within the carrier. Spray drying also is used in producing powders that do not require encapsulation, such as various food products, additives, and chemicals.[0004]Spray drying systems commonly are relative...

AI Technical Summary

Benefits of technology

The present invention introduces a spray dryer system that is designed for better functionality and versatility. This system is compact in size, reliable in operation, and easy to install and operate in various locations without special building requirements. The technical effects include improved efficiency and flexibility, as well as a smaller size and reliable operation.

Problems solved by technology

Spray drying systems commonly are relatively massive in construction, having drying towers that can reach several stories in height.

Heating requirements for the drying medium also can be expensive.

While it is desirable to use electrostatic spray nozzles for generating electrically charged particles that facilitate quicker drying, due to the largely steel construction of such sprayer dryer systems, the electrostatically charged liquid can charge components of the system in a manner, particularly if unintentionally grounded, that can impede operation of electrical controls and interrupt operation, resulting in the discharge of uncharged liquid that is not dried according to specification.

While it is known to form the drying chamber of electrostatic spray dryers of a non metallic material to better insulate the system from the electrically charged liquid, particles can adhere to and build up on the walls of the drying chamber, requiring time consuming cleanup which interrupts the use of the system.

Moreover, very fine dried powder within the atmosphere of heating air in the drying chamber can create a dangerous explosive condition from an inadvertent spark or malfunction of the electrostatic spray nozzle or other components of the system.

Residual flavor material adhering to the walls of the drying chamber can contaminate the taste of subsequently processed products.

Existing spray dryer systems further have lacked easy versatility.

Existing sprayers, however, have not lent themselves to easy alteration to accommodate such changes in processing requirements.

Such fine particulate matter can quickly clog filters, impeding efficient operation of the dryer and requiring frequent cleaning of the filters.

Such equipment is expensive and necessitates costly maintenance and cleaning.

Another issue with spray dryer systems is potential damage to the finished product after completion of the drying process.

In particular, damage to the finished product can occur if it is exposed to moisture-laden process gas, excess heat or oxygen.

For example, some spray-dried products are very hydroscopic and may reabsorb moisture after the spray drying process is completed if the product is exposed too long to the moisture-laden dryer exhaust stream.

While evaporative cooling protects spray-dried products from damage caused by exposure to heat during the spray drying process, some spray-dried products can only tolerate high temperatures for a short period before they begin to denature or otherwise degrade.

Thus, prolonged exposure to a heated exhaust stream can lead to product damage.

Additionally, some products also can oxidize if exposed to oxygen after completion of the drying process.

Another issue with spray dryer systems is potential damage to the finished product after completion of the drying process.

In particular, damage to the finished product can occur if it is exposed to moisture-laden process gas, excess heat or oxygen.

For example, some spray-dried products are very hydroscopic and may reabsorb moisture after the spray drying process is completed if the product is exposed too long to the moisture-laden dryer exhaust stream.

While evaporative cooling protects spray-dried products from damage caused by exposure to heat during the spray drying process, some spray-dried products can only tolerate high temperatures for a short period before they begin to denature or otherwise degrade.

Thus, prolonged exposure to a heated exhaust stream can lead to product damage.

Additionally, some products also can oxidize if exposed to oxygen after completion of the drying process.

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