A Pennsylvania milk company utilises vertical spray dryers to produce large quantities of milk powder. With sizes of up to 22 feet in diameter and up to 60 feet high, the facility’s spray dryers can produce a total upwards of 4,000kg of milk powder per hour.
During the manufacturing process fluid milk is evaporated to 50 per cent solids and then injected under high pressure into the 200-plus°C environment inside the spray dryer where it flash dries.
The dry milk then drops to the bottom of the unit and is discharged into bulk containers. Vibrators help remove any powder which may adhere to the sides of the cone. However, over time, the milk builds up on the inside of the dryer and must be removed during routine cleaning. In order to maintain high production efficiencies and product quality, close attention is paid to maintaining the cleanliness of the spray dryer interiors.
Until recently, the company utilised traditional spray balls and high pressure water injection to clean the dryers. The routine cleaning cycle usually consisted of two 45 minute wash cycles utilising a 2 per cent sodium hydroxide caustic solution and a 1 per cent nitric acid wash, interspersed with 20 to 30 minute rinses.
A thorough cleaning of the entire unit often required up to 16 separate insertions of the spray ball by cleaning personnel into various openings throughout the dryer. This was a very time consuming and labor- intensive operation to ensure that all the areas were cleaned. Water usage throughout the process was approximately 946 litres per minute.
With a standard cleaning process to measure against, the company’s Manager of Engineering and Maintenance had the opportunity to install and utilize two rotary impingement cleaning machines manufactured by Gamajet Cleaning Systems, Inc. The Gamajet 4 and Gamajet E-Z8 cleaning machines are fluid driven tank cleaners that utilize the cleaning solution for power and provide 360° cleaning with low flow rates and high speed.
The Gamajet 4, because of its greater cleaning power, was inserted inside the large upper chamber and dome of the spray dryer, while the Gamajet 8 is positioned in the smaller sized bustle and cone located at the bottom of the unit. During the new cleaning cycle each Gamajet unit is inserted only once resulting in immediate savings in time and manpower.
With the new units, wash times have been reduced to a 15-30 minute cycle and often only one wash is necessary. Because of the Gamajet’s high powered cleaning force, water usage is now estimated to be about 100 gallons per minute. “We estimate that by using the two Gamajet units, we save about two and a half hours in time and around 28390.59 litres of rinse water per cleanup, the Manager says. “And, we also save on the amount of chemicals we use.”