TechNews

When imaging someone being vaccinated we tend to think of big needles in the arm. Well, think again. New techniques such as spray drying allow the vaccine to be given oral.

The important thing, for making this kind of vaccination even possible, is controlling the nanoscale particles size. Spray dryers are brilliant for this purpose because they are designed for production of either dry material or material bound within very small droplets.

Aerosol drugs for inhaling
Droplets are perfect for inhaling. Think of how easy you catch a cold when some sneezes on you. Within the field of tuberculosis a new vaccine has already been developed. It is far cheaper and for countries in Africa where hygiene is a major problem needles should always be avoided if possible.

What is even more interesting is the fact that oral vaccination sometimes for work better than when giving the same vaccination in a needle. Perhaps because the immune system is more suited for developing an immune response to when the treat comes into the body via a natural route, here being the lungs.

Important factors when designing the vaccine
Aerosoll drugs demands for precision work and thus often many different spray drying techniques can be used in optimizing the final vaccine product. Such related techniques could be Spray bed dryers.

Keeping food production expenses low is essential for any production unit if to survive in the ever ongoing global competition.

However, also the food preservation time is essential as the product can stay longer time on the shelves of the super marked. A simple solution to solving both problems is spray drying.

Dry food last longer
First of all the spray dryers simple dry out the product, which means that any micro organism (such as fungi or bacteria) what might survive slipping into the drying plants and through the evaporators will have a very hard time growing as the food product is totally dry.

Second and dry product tend to live longer as water acts as both a solvent that dissolves the product, but also functions as a catalyser which breaks down the preserved product.

One kilogram, one dollar
Second, spray drying is a cheap and fast process that does not necessarily call for large capital investments. The technique is after all getting cheaper and cheaper and it should be no problem to produce 1 kilogram of dry material for 1 dollar or less. 

All in all it seems a win-win situation to implement a spray drying plant.

Commonly the method of drying of liquid feed is done by spray drying. Usually, a warm gas is used, but many solvents are sensitive and therefore require nitrogen because oxygen can be harmful to the solvents.

It should be noted that the solvent is not limited to specific products like e.g. pharmaceuticals, colloid, suspensions, ethanol or food and drinking products. 

It can basically be any product (or material) as long as it is small enough. What actually happens during spray drying is that the liquid feed is pumped straight through a so called atomizing devise or evaporator which separates the product into billions of small droplets or particles, which then are dried in the main chamber of the spray dryer machine.

Simple procedures
What makes spray dryers so cheap is the fact that it only requires a very rapid one step process, which also eliminates any further processing.

However there are many different ways of running this spray drying process, which is beneficial, as the system can be fine tuned for any production unit like small batches or large scale production. Furthermore the temperature does not have to high which means the products do not deteriorate.

Within the field of spray drying there are any methods which more or less resembles one another. For the non professional or someone new in the field a easy guide to overlooking the techniques might be helpful. The aim of this list is not to give a full understanding, but rather a quick description of some of these methods.

Please note that there are several more techniques within the field of spray dryers, which are left out. The most important ones, however, are the one listed below. The list is in alphabetic order:

aseptic spray drying - The word Aseptic refers to a product free of microbiological life forms that otherwise could lead to spoilage of the product. The spray drying process is often used when the intention is long term storage of the product, thus increasing the life span.

ddgs drying - Distillers Dried Grains with Solubles is a product you receive during yeast fermentation after you have removed the ethyl alcohol. The trick is to blend distillers on the wet distiller grain and then afterwards dry it.

disc dryers - Rotating is the key word in disc drying. Usually hot steam heats up the inside of double-walled discs, which are placed within the central tube. Then the product is circulated and shoved through the bundle dryers. To ensure that no products get stuck on the discs scrapers keep mixing the product.

Fluid bed drying - The technique is ideal for products not being sensitive to heat. To fluidize at product a gas is passed through a layer of the product, which then dries. The advantages are high product rates and easy material transport.

Ring dryers - This is basically the same as flash type dryers but the residence time of the product is increased by using a so called centrifugal classifier. The method is suited for large and wet material. Essentially the ring dryers removed the fine and dry material by using a filter. Disintegrators and grinders can also be incorporated.

Spent grain dryers - To say it in short, spent grain dryers are used in the brewery industry and are designed to lower the volume of spent grains being lost.

Tube Bundle Dryers - The tube is used when you want to prevent the product from getting in contact with the steam. It dries while being rotated inside a firm housing. This prevents the product from clogging at temperatures required for drying. Usually the product is pourable and non-sticky. This could be important for starch or distilling industries.

Listening to: Bach

Spray drying is an encapsulating technique, which is often used in food and pharmaceutical industries.  It is one of many more complicated products which are used to produce the medical products we intake when buy medicine. Spray dryers is also used in producing skim milk powders in the food industry. 

But does anybody know what they use evaporators for?