Industrial Centrifuges have been the choice of the dairy processing industry for over 100 yrs. They achieve the high performance requirements of the modern day dairy.
Milk Clarification – The main purpose of milk clariﬁcation is to remove impurities. The efﬁciency of the removal of smaller particles increases with the temperature, and the most efﬁcient reduction of leucocytes and bacteria is achieved at 50–60 °C.
Hot Milk Separation – The objective is to separate the globular milk fat from the serum, the skimmed milk. The separation process is normally incorporated into a pasteurisation line and combined with a separator inline fat standardisation system. The outgoing cream from the separators can contain up to 60 % fat with maintained skimming efﬁciency.
Cold Milk Separation – When heating milk is undesirable and long run times are desirable, separators enables to separate cold milk at 4–15 °C. The viscosity and characteristics of cream at low temperatures make separators the ideal form of separation for this duty. The performance of a cold milk separator is highly dependent on milk quality, operational temperature, ﬂow rate, process control and selection of separator size. The fat content of skimmed milk, for example, can go down to 0.08 % at 4 °C.
Spore & Bacteria Removal – Centrifuge units are traditionally incorporated in the pre-treatment of cheese milk, where typically butter acid spores (Anaerobic spores) are removed. Separator units are also used to enhance the quality of powders, consumption milk and cream where typically aerobic spores (e.g. Bacillus Cerus) are removed. The efﬁciency is stated as a percentage reduction of the incoming level of bacteria and spores. Generally, the efﬁciency can go up to 99 %. For installations with high demand on efﬁciency, two or more units can be installed in series.
Whey Clarification – To maintain optimum fat separation and long run times, it is necessary to remove cheese ﬁnes from the whey before it reaches the whey separator. Installing a centrifugal clariﬁer upstream of the whey separator is the most efﬁcient way to remove cheese ﬁnes. Clarification normally takes place at the same temperature as whey separation, i.e. at vat temperature. Flow rate, fines content and production hours are important parameters in the choice of clariﬁer.
Whey Separation – The aim of whey separation is to recover fat and make the skimmed whey as free from fat as possible, to facilitate downstream treatment and enhance the value of the whey. When pre-clariﬁed, the whey separation becomes more efﬁcient, resulting in a low fat content in the skimmed whey, down to 0.03 %, depending on whey type. Whey separator technology enables dairies to produce high-fat cream with a fat content above 30 % even at temperatures below 35 °C.
Anhydrous Milk Fat Separation – Anhydrous milk fat (AMF) is a product obtained from fresh raw material and has a milk fat content exceeding 99.8 %. Milk fat is concentrated in several steps up to 99.5 %, and is then vacuum treated. Butter oil is produced from raw material of varying age and contains a minimum of 99.3 % milk fat. The raw material, cream or butter (stored or fresh), determines the number of steps required.
Buttermilk Separation – For separation purposes, buttermilk derived from butter production is classiﬁed as either sweet or sour. In the separation of sweet buttermilk, a standard hot milk separator is used at its nominal ﬂow rate. Sour buttermilk contains unstable proteins. Consequently, the general guideline is to use a whey separator or cold milk separator and process at half the nominal ﬂow rate. A fat content of 0.2–0.3 % in the separated buttermilk is expected after separation.
Quark Separation – Quark is a fresh cheese made from coagulated skimmed milk. In non-fat quark, the solids content normally ranges between 14 % and 22 %. The customary separation temperature is 28°C, and takes place immediately after fermentation. Additional heat treatment after fermentation and separation at about 40°C increases the yield. Efﬁciency is calculated in terms of total yield between 3.7 and 4.2 kg milk/kg quark. For separation of the acidiﬁed and fermented skimmed milk, nozzle-type separators are used, where the fresh cheese mass is discharged through the nozzles.
Vertical Continuous Disc Bowl Separators are the primary separators of choice in most separation stages of the dairy processing industry. In addition the Horizontal Continuous Solid Bowl Decanter Centrifuge can also be found treating various effluent streams.