Industrial Air Filtration require filters that will remove/recover Industrial Air Filtration the solid particles from the end product being manufactured such as cement, aspirin, Kaolin, TiO2, powdered milk, baby powder, rice, flour, and many more.
Powdered Milk is big business in the US. Producing over 1 million metric tons makes the US the largest single country producer of SMP/NDM (Skim Milk Powder/ Nonfat Dry Milk). About 50% is being supplied to overseas markets. Whole Milk Powder (WMP) is only about 5% of the US powdered milk production. The US is suppling about 25% of the World’s SMP/NDM requirement. The US has over 330 commercial fluid milk bottling plants, about 1,600 Dairy manufacturing plants, and about 80 powdered milk plants.
The remaining 50 % of powdered milk are sold in the US as reconstituted milk, and as SMP for the confections, bake goods, beverages, and nutritional products. SMP is used in these applications for improved texture which gives a moister product with more flavor and deeper color. Milk powders are much more stable than fresh milk but still need to be protected from moisture, oxygen, light, and temperature.
Fresh milk is purchased from the farmers and trucked to a plant that manufacturing Powdered Milk. It is first placed in a holding tank for processing.
To insure that milk is not scorched, the evaporator has a partial vacuum put on it, lowering the boiling point of the milk to a safe 135 degrees F. Fresh milk has about 12.5 % solids. The evaporator removes water until the solids are increased to about 50 %. Skim milk contains about 91% water. Processing the milk at the higher solids content reduces cost. This slurry is then pasteurized.
The process of elevating the temperature of the slurry to about 175 degrees F for about 20 seconds, and then rapidly cooling it. This brief exposure to the high temperature kills the bacteria.
After the milk is passed through the evaporator it goes through a separation process. The butterfat is removed and stored in a holding tank for future use. Next the resulting Skim Milk move on to the Standardization part of the process.
There are standard butterfat content for all milk, whole milk- Skim 1%-2%-butterfat free, condensed milk, evaporated milk, etc. Butterfat content range from less than 1% to about 30%. The standardizing takes place prior to final stage of the powder processing. This ensures that when the powder is reconstituted it will contain the specific amount of butterfat required for that product.
Drying The Powder
The last step in producing SMP/NDM/WMP is driving off the remaining moisture. One method is a spray dryer where the concentrate is sprayed into a hot air chamber for drying. A concentrate may be heated prior to the spray dyer to improve efficiency. The final drying takes place in a series of fluid bed. A fluid bed is where hot air is blown up through a layer of the powder removing the moisture.
Powdered milk is collected in filter bags. Both conventional bags and ePTFE membrane bags. Collecting the powdered milk is not without challenges. The powder is fine, about 0.1um and depending on the amount of butterfat, makes the powder difficult to dislodge from the bags resulting in a high pressure drop. The challenge is greater when the butterfat of the powder is above 4%. SMP contain 0 to 2% butterfat which is largest powdered milk produced.