Dairy Engineering Textbook PDF

S. Ravi Kumar  DAIRY ENGINEERING Course Developers S. Ravi Kumar Department of Dairy Engineering SVVU, Tirupati Editor 2 Dairy Engineering www.AgriMoon.Com ...

S. Ravi Kumar  DAIRY ENGINEERING Course Developers S. Ravi Kumar Department of Dairy Engineering SVVU, Tirupati Editor 2 Dairy Engineering www.AgriMoon.Com  Dairy Engineering: 3 (2+0+2) Sl No Particulars Module 1: Sanitary pipes, fittings and Milk handling equipment 1.1 Materials and sanitary features of the dairy equipment 1.2 Sanitary pipes and fittings, standard glass piping, plastic tubing, fittings and gaskets 1.3 Installation, care and maintenance of pipes & fittings 1.4 Milk storage tanks, Silos, Road Tankers, Rail Tankers Module 2: Bottle & Cans Washing and CIP cleaning equipment 2.1 Description, working and maintenance of can washers straight - through can washer 2.2 Bottle washers. Factors affecting washing operations, power requirements of can and bottle washers 2.3 CIP and designing of system Module 3: Separation equipment 3.1 Mechanical Separation: Fundamentals involved in separation 3.2 Principals involved in filtration, Types, rates of filtration, pressure drop calculations 3.3 Gravity settling, Sedimentation, Principles of centrifugal separation 3.4 Different types of centrifuges. Application in Dairy Industry, clarifiers, tri processors, cream separator 3.5 Self-disludging centrifuge, Bacto-fuge, care and maintenance of separators and clarifiers 3.6 Solving numerical Module 4: Homogenizers 4.1 Homogenization : Classification, single stage and two stage homogenizer pumps, power requirement for homogenization 4.2 care and maintenance of homogenizers, aseptic homogenizers 4.3 Solving numerical Module 5: Pasteurizers 5.1 Pasteurization: Batch, flash and continuous (HTST) pasteurizers 5.2 Pasteurizer control, Flow diversion valve 5.3 Care and maintenance of pasteurizer 5.4 Solving numerical Module 6: Sterilizing & Packing equipment 6.1 Different types of sterilizers, in- bottle sterilizers, autoclaves 6.2 Continuous sterilization plant, UHT sterilization 6.3 Aseptic packaging and equipment. Care and maintenance of Sterilizers. 6.4 Solving numerical Module 7: Filling equipment 7.1 Filling Operation: Principles and working of different types of bottle fillers and capping machine 7.2 Pouch filling machine, Form-Fill-Seal Types 7.3 Aseptic filling by bulk handling system, care and maintenance Module 8: Mixing and agitation equipment 8.1 Mixing and agitation 8.2 Power consumption of mixer-impeller, selection of mixing equipment in dairy industry, mixing pumps 8.3 Solving numerical 3 Dairy Engineering www.AgriMoon.Com  Lesson-1 Materials and Sanitary Features of the Dairy Equipment 1.0 INTRODUCTION Pipes, fittings, valves and other milk handling equipment in a Dairy plant play an important role in the maintenance of the quality of the product as well as cost of the plant installation. Some features like the pressure drop, cost optimizations etc are common to the general principles of hydraulics. But there are also some important aspects of the design which are specific to food and dairy industry, because of the hygiene considerations. The special features of that are applicable to the dairy industry are listed below: 1.1 SANITARY FEATURES o Equipment is easily accessible & readily cleanable either in an assembled position or when disassembled. Removable parts are readily demountable. o All product contact surfaces are self-draining. o When assembled, no pipe or fitting threads are exposed to the product. (Eg. Milk storage tank legs, pasteurizer frame etc. Further, the easily cleanable threads like SMS type are preferred over Acme threads. o All permanent joints are welded and grounded to smooth finish. o Interior surfaces are smooth and even, especially at joints, thus eliminating crevices and projections. o Gaskets are eliminated wherever possible. If used, they should be smooth, non-toxic and product resistant. They should not contribute to off flavors in the product. o Possibility of processing under vacuum, which make the equipment susceptible for external contamination. 4 Dairy Engineering www.AgriMoon.Com o Effective velocity of flow and optimum agitation to prevent surface film formation. o Pre-heating the product with external devices. o Providing large vapour space where water to be removed. o Rapid removal of water vapour. o Avoiding air leaks. 1.2 SPECIFIC REQUIREMENTS OF DAIRY PRODUCTS Most of the Dairy Equipment:  Are worked continuously throughout the year hence more wear and tear  Have wide temperature variations during operations  Have to with stand effects of water, steam, brine, refrigerants cleaning and sanitizing solutions.  Are disassembled very frequently and hence exposed to damage of components  Sanitary conditions are of paramount importance in dairy and Food industry. Hence to achieve the above requirements, the equipments must be designed and materials chosen suitably.  Dust proof, corrosion resistant external surface  Smooth polished internal surface  Minimum clearance of 100 mm between equipment base and floor with ball foot  Absence of sharp corners and edges  Elimination of vertical dead spaces or passages and capped tees  Proper slope towards drain points  Properly ground and polished welds  Raised edge opening to prevent surface drainage in to container.  Sanitary type inlet and outlet fittings. The following diagrams give an indication of the requirements of dairy industry that may differ from general principles of equipment design. 5 Dairy Engineering www.AgriMoon.Com  Animation Dairy Equipment Design 1 Even the support and other attachments that are not coming directly in contact with the milk and milk products should be designed to avoid accumulation of dust and soil. Animation Dairy Equipment Design 2 Animation Dairy Equipment Design 3 6 Dairy Engineering www.AgriMoon.Com  Fig.1.1 Turbulance Table 1.1Characteristic of different alloys of Stainless Steel: Chromium Martensitic Hardenable 400 series contain large amounts of Types (403,410,414,416,416Se,420,431,440 series) chromium and little or no nickel Ferritic Non-hardenable (405,430,430F,430Se,442,446) Chromium- Austenitic Non-hardenable, except by cold working 300 series contain (201,202,301,302,302B,303,303Se,304,304L,305,308 large amounts of Nickel ,309,309S,310,310S,314,316,316L,317,321,347,348) chromium and nickel Types Semi- Strengthened by ageing or precipitation- austenitic hardening Precipitation-hardening Martensitic Precipitation hardening 1.3 MATERIALS COMMONLY USED IN DAIRY INDUSTRY Materials used for the construction of dairy equipment also play an important role in the sanit ary design and maintenance of hygiene. They are broadly divided into those parts of equipment that come in contact with the milk and milk products and those which do not come in contact and only act as structural components (supports, insulation and protective coverings) and other service equipment. The commonly used materials are: Iron, Steel, Stainless steel, Aluminum, Insulation materials, Plastics, Glass etc. 7 Dairy Engineering www.AgriMoon.Com 1.3.1 Iron and steel These are mostly used in the structures that are not coming in contact with milk. Iron added with Carbon is Steel. Depending on the percentage of carbon present, the steel is further divided in to Mild steel, Low carbon steel etc. Further, Steel with Chromium content more than 10.5% is called Stainless Steel (SS). It is Table 1.2 Materials used as structural components Heavy equipment beds Difficult to weld, brittle in nature Cast Iron Main castings of engines 2 to 4.5% Cannot be forged Gear box cases Easily welded, tough, ductile, Chains, Hooks, couplings, Wrought Iron 0.06 to 0.08% malleable rivets, shock loading parts Highly ductile, malleable, tough, strong, easily welded, Structural elements, Mild Steel possesses magnetic building equipment, 0.1 to 0.25% properties, can be cast & conveyor frames forged Particularly used where corrosion is minimum, and where the material is coming in contact with milk and milk products. Different proportions of Nickel are also added. The Stainless Steels are broadly divided into Martensitic, Ferritic and Austenitic. They are classifie d into different grades. Of particular importance is the AISI 304 AND AISI 316 grade of stainless steels. AISI 304 is used for construction of pipes, fittings, silos, tanks and vessels. AISI 316 is used for fabrication of plates of plate heat exchangers, CIP tanks, evaporator tubes which needs higher corrosion resistance. 8 Dairy Engineering www.AgriMoon.Com  Table 1.3 Chemical composition of AISI 304 and AISI 316 SS AISI 304 AISI 316 Component Remarks (% max.) (% max.) Carbon 0.08 0.10 0.04% for Low carbon grades Manganese 2.0 2.0 Improves wear resistance Phosphorous 0.04 0.04 Sulphur 0.03 0.03 Improves machining properties Silicon 1.0 1.0 Improves resistance to heat & chemicals Chromium 18 – 20 16 – 18 Harden ability Nickel 8 – 10 10 – 14 Improves toughness & corrosion resistance Molybdenum --- 2 – 3% Increases resistance to corrosion Aluminum is mostly used for making milk cans, but the trend now is to shift to stainless steel for better hygiene. It is light in weight, insoluble in milk, does not impart any flavor and can be spun i nto various shapes. But it is porous in nature, making it difficult to weld. Resistance to abrasion is poor, and gives gray stain. The surface is generally given Anodizing treatment in which parts to be treated is made anode and dipped in electrolytic bath (of sulphuric, chromic or oxalic acid) to form a colour less and stable film on the surface. Plastics have wide range of applications, and are broadly classified into Thermoplastics and Thermosetting plastics. Thermoplastics are manufactured by process called addition polymerization. They are liquids at higher temperature and crystallize readily at low temperatures because of simpler molecular structure. They generally show poor resistance to organic liquids. They are generally straight chain polymers, and have no cross links. The common items that are used in dairy industry of the above category are Poly Tetra Flouro Ethylene (PTFE), Poly Ethylene (HDPE & LDPE), Poly Venyle Chloride (PVC), Acrylonitrile butadiene styrene (ABS), Cellulose acetate butyrate (CAB) etc. PTFE is used for pump shaft seal. Thermostetting plastics on the other hand have cross links in their structure, and undergo permanent changes when raised to higher temperatures. Hence, they cannot be recycled. The common items that are used in dairy industry are Fibre Reinforced Plastic (FRP) storage tanks, Epoxy glass, polyester 9 Dairy Engineering www.AgriMoon.Com reinforced glass, plastic gears, Phenol formaldehyde, and Elastomers like Polybutadiene and Polychloroprene (Neoprene). ******☺ ****** 10 Dairy Engineering www.AgriMoon.Com  Lesson-2 Sanitary Pipes and Fittings, Glass Piping, Plastic Tubing, Fittings and Gaskets 2.1 INTRODUCTION Design and selection of pipes for handling milk and fluid milk products has to be done with same care and attention to sanitary features as is done for the dairy equipment, where the surfaces are coming in contact with the product. The type of material has to be Stainless Steel of grade 304 or 316. As milk flows with high velocity hence, the corrosion due to erosion as well as pitting has to be factored in while designing. In some of the instances, instrumentation for measuring the properties of the flowing fluid will be required, and need special type of pipe fittings. Care also has to be taken regarding the surface finish, both inside and outside of the pipe lines. In general, the following aspects are important in design of sanitary type of pipes. 2.2 GENERAL POINTS TO BE CONSIDERED WHILE DESIGNING AND LAYOUT OF SANITARY PIPE LINES ARE GIVEN BELOW 1. Pipes should be seamless and preferably cold drawn 2. They should softened, descaled and pickled 3. Polished internally and externally 4. Clean, smooth and free from surface defects, straight and free from longitudinal grooving both inside and outside 5. Material for fittings to be same as that of pipe 6. The condensate from the surface of milk pipe lines should not be allowed to fall on places where unhygienic conditions or milk contamination is likely to occur 7. The capacity of the pipe line should be designed to allow the flow within the limits, without much pressures loss Table 2.1 Outer diameter, thickness and carrying capacities of sanitary pipes Approx. O.D Thickness Capacity (Kg/h) 25.4 mm 1.25 mm < 2000 38.1 mm 1.25 mm