The list and sequence of operations are determined based on the specific production conditions and the set goal.

Among the possible operations of primary processing of milk in agricultural enterprises, the most widespread are cleaning, pasteurization and cooling (Fig. 67).

Rice. 67. Structure of primary milk processing operations.

In those cases when milk from livestock enterprises is sold directly to the population, individual milk processing operations are often included in the technological schemes of primary processing.

Milk processing aims to produce drinking milk, cream, cottage cheese, butter, cheese and other dairy products. Some farms use equipment to receive milk and carry out its separation, normalization and homogenization.

The simplest technological scheme for the primary processing of milk includes its cleaning and cooling and is carried out with equipment that is part of modern milking units. This scheme is quite sufficient for livestock farms that are located near dairy processing plants.

In those cases where the farm is located far from industrial enterprises, as well as with unsatisfactory communication routes with milk receiving points, the milk that enters the milk receiving department after milking the cows is sent to a separator-cleaner, then for pasteurization and, after cooling, for storage in milk tank.

Some large suburban farms prepare drinking milk for sale in retail chains and use the following technological scheme: cleaning - pasteurization - cooling - packaging in small containers.

Farms located far from milk-consuming cities use technologies that include milk processing operations, for example: cleaning - pasteurization - separation to produce high-fat cream - mechanical processing of cream with cooling - production of butter; cleaning - pasteurization - separation to obtain medium-fat cream - aging of cream - production of butter.

7.4.3 Machines and equipment for primary processing of milk. Types and general assessment of milk purification

Milk purification- this is the removal of various mechanical inclusions and impurities. Depending on the milking machines used, the following are used:

Filters in the form of gauze folded in three to five layers, flannel - two to three layers, gauze with layers of cotton wool, brass, nylon and lavsan meshes;

Separators-cleaners (centrifugal milk purification).

The following requirements apply to filter materials:

High hygroscopicity and ability to retain small impurities;

Preservation of high moisture conductivity in a contaminated state;

Relatively easy separation of accumulated contaminants when washing filters;

Minimum and stable hydraulic resistance;

High mechanical strength and resistance to abrasion of filter threads under repeated bending and tension;

Low cost of filter material.

Filter throughput, kg/h:

, (28)

Where F- total filter area, m2; V is the speed of milk flow through the filter, m/h; p is the density of milk, kg/m3.

Total filter area, m2:

(29)

Where F 0 - cross-sectional area of ​​one filter hole, m2; P- number of holes.

Speed ​​of milk flow through the filter, m/h,

, (30)

where μ is the coefficient of milk flow (c = 0.8); g- gravity acceleration, m/s 2 ; h is the height of the product column above the filter, m.

Area of ​​filter fabric required to filter milk, m2,

. (31)

Where M - amount of milk to be filtered, l; q is the amount of milk passing through 1 m2 of filter fabric, l/m2.

When purifying milk using a separator-cleaner, determine the continuous operation time, h,

, (32)

Where V G p - volume of mud space of the drum, l; R - percentage of separator mucus deposition from the total volume of milk passed through (P= 0,03...0,06 %); L - purifier productivity, l/h.

Capacity of the mud space of the separator-cleaner drum, l,

, (33)

Where R max And R min - maximum and minimum radii of the mud space, cm; N - height of the drum cymbal package, cm.

During purification, mechanical and partially bacteriological impurities are removed from milk, which improves its quality and creates the prerequisites for longer storage.

Depending on the design, milk filters are divided into: open and closed. In open ones, milk passes through the filter membrane under the influence of hydrostatic pressure, so they have low productivity and quickly become dirty. In closed filters, milk passes through the fabric under pressure.

Open type strainers are used when milking in portable buckets. Strainer filters are installed on the necks of flasks, milk tanks and other containers.

Rice. 68. Cylindrical filters with reusable (a) and disposable (b) elements:

1,7 - sealing gaskets; 2 - frame; 3 - filter element; 4 - ring; 5 - screw; 6 – adapter; 8 -frame; 9 - cork; 10 – milk pipeline.

Modern milking units are equipped with cylindrical milk filters (Fig. 68) installed in series in the milk pipeline.

In practice, milk filters are used, the working elements of which are: cotton pads, gauze, flange, paper, metal mesh, synthetic fabrics (lavsan, etc.).

Compared to cotton filter elements, synthetic materials have a more stable filtration rate, higher bacteriological purity and strength, and are easy to clean and sterilize. However, even the use of the most advanced filter materials does not ensure complete purification of milk from mechanical, much less bacterial, inclusions. In addition, the surface of the filter quickly becomes contaminated with a layer of impurities, which leads to an increase in the number of bacteria in the milk passing through such a contaminated layer. In case of prolonged use of the filter, the remaining organic impurities decompose and sharply increase the microbial flora.

Recently, disposable paper filters have become widespread. They are easier to use and provide better milk purification.

A much more advanced way of filtering and purifying milk is centrifugal purification. In this case, the milk is cleared not only of mechanical inclusions, but also of mucus, epithelial clots and blood that appear in the milk due to udder disease. Unlike filtration, during centrifugal cleaning, milk does not wash away contaminants that are deposited in the mud space of the purifier.

For farm dairy and milk processing enterprises, the industry produces centrifugal separator-cleaners of various standard sizes according to productivity. They are distinguished by high throughput, reliable operation, and provide high quality milk purification.

In order to streamline the design and configuration of equipment for milking and dairy units of livestock farms and complexes supplying Milk to dairy industry enterprises, diagrams of technological lines for milk processing on farms were developed (3). Eight schemes are recommended, which use commercially produced equipment, selected in kits, for farms and complexes with a population of 200 to 2000 cows, and two schemes for free-standing central farm dairy farms. In all schemes in case of animal epizootics, technological equipment for pasteurization of milk is provided - batch and continuous pasteurizers.

All standard projects of milking and dairy blocks of livestock farms and complexes are developed in accordance with these technological schemes of dairy lines. Equipment for processing milk must ensure its high quality and compliance with the requirements of the milk standard. GOST 13264-88 provides for mandatory primary processing of milk directly on the farm - cooling it to a temperature not higher than 1O degrees

All operations associated with the primary processing of milk are divided into main and auxiliary. The main operations include mechanical and thermal processing, auxiliary operations include receiving, weighing and transporting milk, as well as washing and sterilizing dishes. Mechanical processing includes cleaning. normalization, separation; thermal - cooling and heating. Primary milk processing is carried out in production lines on modern milking machines according to the scheme milking - cleaning - cooling - storage at low temperatures. On large farms, centralized on-farm dairy facilities are built, where it is possible

carry out partial processing of milk. If milk from the farm goes directly to shops, canteens, hospitals, and child care institutions. then it is processed a second time, i.e. purified in centrifugal purifiers, normalized for fat content, pasteurized, cooled and packaged in small containers.

Knowing the amount of milk. milked in 1 hour, calculate the technological line for processing and storing milk in accordance with zootechnical requirements for machines and equipment.

The hourly productivity of the milking line varies during different periods of milking, and the productivity of technological equipment for processing milk is usually constant, so the flow of the line as a whole is achieved by including surge tanks. Its volume is determined by the formula

Vtank= (Qh - Qm. l) T,

where Qm. l - productivity of the milk processing technological line, t/h.

The surge tank is selected after determining its theoretical capacity. Typically, tanks PB-ORM-0.5, PB-ORM-1, O and PB-ORM1-2, O are used with working capacities of 0.5, respectively; 1, O and 2, O m 3

The milk is weighed on SMI-250M and SMI-500M scales, which have receiving baths (reservoirs) with a capacity of 250 and 600 DM 3 , respectively.

Milk is purified from impurities by filtration and centrifugal method. The milk is filtered in the flow with gauze. flannel or lavsan filters. The centrifugal method of purifying milk from mechanical impurities using a separator - milk purifier OMA-EM and milk purifiers of the OM-1A unit is more advanced. It is used in production lines.

The milk separator-cleaner OMA-3M is used in the pasteurization installation SPU-3M and OP2-U5.

The milk is cooled in a stream using spray (open) or plate (closed) milk coolers. The coolant in them is water or brine.

Coolers are equipped with pumps to supply coolant and milk.

Heated water from the milk cooling section with tap water can be directed into the water supply system - into the automatic watering system for animals, which will give a significant economic effect.

The need for artificial cold (J/h) is calculated using the formula

Q hall = Q m. lC (tn - tk),

where c is the specific heat capacity of 1 milk, J/kg ~C (c = 3920); tH and tk are the initial and final temperatures of milk, respectively, C

Milk cooled below 10 degrees. stored in vertical (V2-OMV-2.5 and V2-OMV-6Z) or horizontal (V2-OMG-4 and 62-OM G-1O) tanks with volumes of 2500, 6300, 4000 and 10,000 dm3, respectively. They are guaranteed to increase milk temperature for 12 hours by no more than 1C when the temperature difference between the ambient air and the milk is 2O C.

If milk is removed from the farm after several milkings, it is stored in cooling tanks equipped with refrigeration units.

The volume of the bath is selected depending on the amount of accumulated milk.

Cooling tanks TOM-1 TOV-1, AKHU-1000, SM-1250 (Poland) are widely used in agriculture. TOM-2A and MK-20 (Germany). horizontal semi-cylindrical milk cooling tanks RPYU-1, b and RPO-2, 5. series DXCRГ DXCE. DXCEM (Sweden), direct cooling tanks MKA-2000L-2A, RNO-1.6 and RNO-2.5.

Artificial cold for cooling water or brine (coolants) is obtained in a refrigeration unit. In agricultural production, refrigeration units of the type MVT - 14 - 1-O, MVT-2O-1-O, MKT-14-2-S are mainly used. MKT-20-2-O and MKT-28-2-O. water-cooling units with partial cold accumulation UV-1O-O1 and AV-ZO, refrigerating machines with cold accumulation MHU-12T and TKHU-14 for producing cold and warm water.

Milk supplied to consumers is pasteurized. to avoid the occurrence of an epizootic. In continuous processing lines, it is first regenerated (heated with hot milk used for cooling) and then pasteurized. Regenerators allow you to increase the productivity of the pasteurizer. reduce steam consumption for pasteurization and reduce the size of the cooler. Milk is pasteurized in long-term pasteurization baths Gb-OPB-300, G6-OPV-600, G6-OPB-1O00, respectively, with a volume of 300, 600, 1000 dm3 and a heating surface of 2; 3~2~ 4.2 m 2 .

The industry produces new automated plate pasteurization and cooling units.

A1 - OKL-3, AK-1-OKL-5, A1-OKL-10 with a capacity of 3000, 5000, 10,000 dm/h, respectively. The milk holding time is 25 s. Recovery rate 87%. The heat exchange surfaces of the plate heat exchangers of the installations are 14, 24 and 50 m respectively. The specific steam consumption per 1000 dm3 of milk is 17.5 kg. In installations of the A1-OKL type, milk is cleaned of mechanical impurities using self-discharging separators-milk purifiers of the series A1-OTsM to obtain cream and skim milk, as well as to normalize milk based on fat content, it is separated using separators SOM-3~10O0M, SPMF-2000 and OSP-3M. After calculating the main equipment for processing and partial processing of milk, transport and auxiliary operations of the process are determined. Transportation of milk. Milk from farms is delivered to the dairy plant in most cases by tanker trucks from the milk producing farm, or in the case of centralized transportation, by tanker trucks from the processing plant. In agriculture, ATSGIT-O tank trucks are used for this purpose. 9, ACPT-1,7, ACPT-I. 9, ATsPT 2. 1, ATsLT-2,8, ATsPT-Z3, ATsPT-5b, ATsG1T-6, 2. ATsG1T-12. The numbers on the brand show the volume of the tank (m3).

Tanker trucks make it possible to reduce labor costs and maintenance costs, and reduce milk losses by 0.1..0I2% compared to transporting it in flasks. It is necessary to select a brand and determine the farm's need for tanker trucks in accordance with the daily volume and one-time removal of chilled milk. It should be borne in mind that the cost per ton-kilometer when transporting milk depends on the delivery distance and the volume of the tank truck. It is more economically profitable to use tanks with a large load capacity. At large dairy complexes, the share of intra-farm milk transportation is significantly increasing. In this case, the construction of near-farm transport pressure milk pipelines for collecting milk from individual blocks in the general dairy is also very effective. Underground transportation of milk through pipes with compressed air using an embedded part - a mechanical separator (3) is also used. This eliminates the loss of milk and removes the remaining washing liquids from the walls of the milk pipeline, and slightly reduces the temperature of the milk. Underground milk pipelines are made of polyethylene pipes (11..50 mm in diameter and more than 10 km in length), which are laid below the freezing level of the soil. The methodology for calculating various types of milk pipelines and MILK LINE devices is described in detail in specialized literature.

The dairy industry is one of the most important areas of cattle breeding. In order for a dairy product to retain its beneficial qualities, you need to know about proper processing and processing. This includes not only cooling and transportation to the dairy plant, but also determination of acidity and fat content, quality control, and sanitary tests.

Fresh whole milk most often acts as a raw material for the production of dairy products. Whole milk has a number of components useful for humans, but working with such raw materials is very difficult: it is multi-component, has inadequate technological and functional properties, and increased activity of biological components. Milk processing technology is designed to preserve all the beneficial properties, as well as increase the shelf life of the finished product and enrich it with vitamins. Milk processing technology includes a whole range of different biochemical and microbiological, thermophysical and chemical, as well as biotechnological measures.

Full cycle of milk processing - diagram

Milk processing technology makes it possible to obtain not only whole milk or pasteurized milk, but also all kinds of dairy and fermented milk products.

Modern milk processing technology requires that the whole product be cleansed of excess fat, since high fat content is not suitable for all people and can be harmful to health. Basic cleansing involves removing any non-food contaminants.

Processing stages

Milk processing today is the result of many years of Russian and foreign research. Milking cows and primary processing of milk (cleaning and cooling) is an important point for subsequent processing of the product. Most often, on large farms, cows are milked using milking machines. This makes milking easier, increases milk yield and ensures that the product automatically enters a special sealed tank.

The future taste qualities of the product largely depend on correct storage and timely transportation to the milk processing plant.

Shipping

The technology for the production of milk and dairy products includes several stages. And transportation is the first of them. The success of transportation depends on the fulfillment of several mandatory requirements:

• Be fast
• Car tanks must maintain a certain microclimate,
• The car must comply with sanitary standards,
• Reception of milk should occur quickly,
• Tanks for transportation must have special equipment that monitors the temperature of the product being transported,
• Transportation must be carried out only in tanks made of materials approved for transportation of food products,
• Transportation must be carried out within the first 20 hours after receiving and cooling the raw materials.

Milk tanker for transporting milk from a farm

Preparing the product for rolling

The second stage in processing is preparing the product for rolling. After the milk has been purified, it is pasteurized. Simultaneously with the pasteurization process, a vacuum conditioning procedure is carried out to remove possible impurities of air and gases, as well as various compounds, from the product. Vacuum conditioning also improves coagulability by approximately 20%.

When the process is completed, the product is cooled and sent either to a special bath or to a cheese manufacturer.

Milk curdling tank

Baktofiguration

In order to avoid an increase in the number of gas-forming bacteria, a small solution of potassium and sodium nitrate is added to the milk. This process is very important. Whole milk contains a lot of butyric and lactic acid enzymes, which can have a negative effect on the final milk product. About twenty grams of a chemical compound is added to one hundred grams of raw milk raw materials, and the bactofiguration process itself lasts an average of 12 hours.

Pasteurization

Pasteurization is a type of heat treatment of a product, in which milk is heated to the required temperature (minimum 63 degrees). This is one of the simplest and most accessible methods of disinfection, which destroys pathogens of diseases such as brucellosis, tuberculosis, and salmonellosis.

Dairy products today are impossible without pasteurization.

There are three types of pasteurization:

• Long-term (minimum time - 30 minutes at a temperature of +63 + 66 degrees),
• Short-term (processing time - 20 minutes, heating temperature + 73 +76 degrees),
• Instant (processing time - a few seconds, temperature + 92 degrees).

Sterilization process

Sterilized milk should not be confused with pasteurized milk. Sterilization of milk is a heating process under special conditions that ensure the complete destruction of both the bacteria themselves and their spores. Sterilization occurs at temperatures above +130 degrees and at higher pressure. After sterilization is completed, the product goes through a cooling and packaging process. Sterilized milk has a long shelf life, but it is not suitable for the manufacture of any dairy products, and also has a reduced content of beneficial bacteria and vitamins.

Homogenization

Homogenization is a very important process during sterilization. Homogenization of milk is aimed at improving the digestibility of the product, as well as preventing cream from settling. Milk homogenization involves crushing milk fat globules.

Equipment required for processing

Any dairy plant must have the necessary equipment for milk processing. Minimum list of equipment for a dairy enterprise:

• Devices for receiving and subsequent storage of processed milk,
• Plate, batch and tubular pasteurizers,
• Separators,
• Piston homogenizers,
• Various containers,
• Equipment for bottling and packaging,
• Powerful compressors,
• piping system,
• Boilers,
• Pump system,
• Special milk filter.

The milk processing workshop must also be equipped with a reliable water supply and electricity system, have good ventilation and fire safety, and a sanitary control zone.

Milk stirring bath

Any dairy processing plant must have a quality analyzer.

One of the most popular models on the market is Lactan 1-4. It shows fairly accurate data, is lightweight and practical, has an autonomous power supply, and is included in the state register not only of Russia, but also of many countries in Asia and Europe.

Dairy

Further processing and processing depends on what type of product the dairy plant intends to receive. Milk processing products:

• Yogurts,
• Cream,
• Oil,
• Ayran,
• Cottage cheese,
• Fermented milk drinks,
• Acidophilus,
• Sour cream,
• Matsoni,
• Melted butter.

Obtaining and benefits of skim milk

A very important processed product is skim milk, which is used both for drinking and for preparing other low-fat products. Skim milk or skim milk is obtained by separating the whole product into cream. If the cream is of standard fat content, then from 0.03 to 0.06% fat ends up in the return. Fat globules with a diameter of less than 2 microns most often end up in skim milk. Skim milk is distinguished by the fact that it contains almost no milk globule proteins, and also by the fact that it has greater biological value than whole milk. Also, skim milk is much richer in amino acids essential for the human body: valine, lysine, leucine, threonine, isoleucine, phenylalanine.

Determination of fat content

Determining fat in milk is very important both for subsequent use and for determining the cost of the product. There are several ways to determine the fat content of milk. Typically, factories and dairy farms use high-precision butyrometers. The device is able to determine the fat content of milk with an error of up to a thousandth of a percent. The disadvantage of the device is the price and the inability to use it at home. In order to determine the fat content of milk in a home farm, you need an ordinary transparent glass, at least 15 cm high, and a measuring ruler. A line is drawn ten centimeters from the bottom of the glass, up to which the milk is poured. The glass is left for seven to eight hours at room temperature - usually enough time for the cream to separate and rise. The thickness of the cream is measured with a ruler. To determine the fat content of milk, you need to divide the thickness of the cream by ten and multiply the result by one hundred percent.

Butyrometer

A device for measuring the fat content of milk (butyrometer) - butyrometer. Butyrometers are widely used in the dairy industry, but using them at home can even be dangerous. The device for determining the fat content of milk works like this: first, 10 ml of sulfuric acid is poured into it. Next, about 11 ml of milk is added to the acid. It is very important to try to prevent the liquids from mixing. The next step is to add one milliliter of isoamyl alcohol. Be sure to do everything in the specified sequence, otherwise the results obtained will not be accurate. The butyrometer should be closed with a tight, preferably rubber, stopper and all contents should be mixed. The device is placed for five minutes in a water bath with a temperature of about 64 - 66 degrees. Next, the butyrometer is inserted into the centrifuge and centrifuged for no more than five to seven minutes. The last step is to place the device in a water bath for three minutes. The fat percentage will be displayed on the device scale.

Which milk has more fat?

Is there a difference in the fat content of milk, which milk is fattier - morning or evening? Morning milk is richer in fats. The explanation for this is simple - more time passes between evening and morning milking. Morning milk is much easier to digest, but evening milk is fattier and contains a higher percentage of cream. This is why evening milk is better suited for preparing a wide variety of dairy products.

But the fat content of the milk yield depends not only on what time the cow is milked, but also on what she ate, as well as on the lactation period.

Acidity

Determining the acidity of milk is also an important point in the processing process. Acidity is taken into account both when assessing raw materials and during subsequent use. Different types of milk can have different acidity levels and differ significantly from each other. It depends on the breed of the cow, and on the season, and on the age, and on whether milk was milked in the morning or in the evening.

Drinking milk and dairy products should be made only from fresh raw materials with an acidity of about 17-18%. If the acidity of the raw material is several percent higher, this is acceptable. If it is 22-23%, then the raw material is considered stale and is not allowed for processing at the plant.

The acidity of the product can be determined as follows: pour about 10 ml of the product into a glass with a pipette, then add 20 ml distilled water and a few drops of phenolphthalein. The mixture is titrated with sodium hydroxide solution until a pale pink tint is formed. The volume of alkali that was required to titrate the mixture is multiplied by ten. And the result is acidity.

Microbiology

The microbiology of milk and dairy products is an important scientific component of any stage of processing. Different types of milk from different cows have different microflora. Dangerous pathogenic bacteria can live in the nipples of the udder, as well as in the milk ducts, and get into the fresh milk with milking. Proper and rapid cooling and subsequent storage of milk will avoid the rapid development of negative microflora. If you leave fresh milk at room temperature, then within a day the number of pathogenic bacteria in it can increase three times. And in milk cooled to +8 degrees, the number of microbes is several times less.

When refrigerating, it is very important to prevent freezing. Such raw materials will be unsuitable for subsequent use. The freezing point of milk is 0.525 - 0.565 degrees.

The average incubation period of microbes is about two days. After 40-48, the bacteria begin the stage of active reproduction and the product turns sour and becomes unsuitable for consumption. That is why it is important to cool the milk in time before transporting it to the dairy plant, and to exclude any contact with air.

Modern technology of milk and dairy products has a number of processes aimed at reducing pathogenic microbes and bacteria in the final dairy product.

Any dairy product also has its own microbiology. The safest product from a microbiological point of view is condensed milk. Only a small amount of spore bacteria can survive in it. This is explained by the fact that condensed milk undergoes both pasteurization and sterilization. Powdered milk is less safe. When producing milk powder, the product is briefly heated, and drying is performed at an insufficiently high temperature. The result is that the finished product may contain spores of many bacteria and even molds. The microflora of cheeses and any fermented milk products is very dependent on the quality of the original raw materials, but most often it is represented by bacteria and organisms that are responsible for the process of souring and fermentation.

Veterinary and sanitary examination

The production of milk and dairy products is not the final stage of processing. The processing plant sends not only finished milk and dairy products for examination. Raw materials received at the plant for processing also undergo a special examination. The purpose of the veterinary examination is to control quality and safety at all stages of processing - from acceptance to sale.

The VSE of milk consists of:

• Study of accompanying documents (veterinary certificates, technical documentation for the vehicle, certificates of conformity),
• Tank inspection,
• Sampling of raw materials,
• Organoleptic examination of raw materials,
• Determination of physical and chemical properties of raw materials,
• Temperature definitions,
• Determination of acidity and fat content,
• Determination of raw material density,
• Determination of raw material purity,
• Determination of dry fat-free and dry residue in raw materials (somo),
• Determination of the coli-titer of raw materials,
• Somatic cell definitions,
• Determining the quality of product pasteurization,
• Detection of the presence of alkaline phosphatase,
• Definitions of falsification of raw materials,
• Determination of the presence of inhibitory components.

The dairy itself, as well as the farm for breeding and keeping cattle, must have the necessary documentation from the sanitary and veterinary service.

Machines and equipment for primary milk processing. Types and general assessment of milk purification

Milk purification- this is the removal of various mechanical inclusions and impurities. Taking into account the dependence on the milking machines used, the following are used:

Filters in the form of gauze folded in three to five layers, flannel - two to three layers, gauze with layers of cotton wool, brass, nylon and lavsan meshes;

Separators-cleaners (centrifugal milk purification).

The following requirements apply to filter materials:

High hygroscopicity and ability to retain small impurities;

Preservation of high moisture conductivity in a contaminated state;

Relatively easy separation of accumulated contaminants when washing filters;

Minimum and stable hydraulic resistance;

High mechanical strength and resistance to abrasion of filter threads under repeated bending and tension;

Low cost of filter material.

Filter throughput, kg/h:

Where F- total filter area, m2; V is the speed of milk flow through the filter, m/h; p is the density of milk, kg/m3.

Total filter area, m2:

Where F 0- cross-sectional area of ​​one filter hole, m2; P- number of holes.

Speed ​​of milk flow through the filter, m/h,

where μ is the coefficient of milk flow (c = 0.8); g - acceleration of gravity, m/s 2; h is the height of the product column above the filter, m.

Area of ​​filter fabric, which is extremely important for filtering milk, m2,

Where M - amount of milk to be filtered, l; q is the amount of milk passing through 1 m2 of filter fabric, l/m2.

When purifying milk using a separator-cleaner, determine the continuous operation time, h,

, (32)

Where V g p - volume of mud space of the drum, l; R - percentage of separator mucus deposition from the total volume of milk passed through (P= 0,03...0,06 %); L- purifier productivity, l/h.

Capacity of the mud space of the separator-cleaner drum, l,

, (33)

Where Rmax And Rmin- maximum and minimum radii of the mud space, cm; N - height of the drum cymbal package, cm.

During purification, mechanical and partially bacteriological impurities are removed from milk, which improves its quality and creates the prerequisites for longer storage.

Taking into account the dependence on performance, milk filters are divided into: open and closed. In open ones, milk passes through the filter membrane under the influence of hydrostatic pressure, so they have low productivity and quickly become dirty. In closed filters, milk passes through the fabric under pressure.

Open type strainers are used when milking in portable buckets. Strainer filters are installed on the necks of flasks, milk tanks and other containers.

Rice. 68. Cylindrical filters with reusable (a) and disposable (b) elements:

1,7 - sealing gaskets; 2 - frame; 3 - filter element; 4 - ring; 5 - screw; 6 – adapter; 8 -frame; 9 - cork; 10 – milk pipeline.

Modern milking units are equipped with cylindrical milk filters (Fig. 68) installed in series in the milk pipeline.

In practice, milk filters are used, the working elements of which are: cotton pads, gauze, flange, paper, metal mesh, synthetic fabrics (lavsan, etc.).

Compared to cotton filter elements, synthetic materials have a more stable filtration rate, higher bacteriological purity and strength, and are easy to clean and sterilize. At the same time, even the use of the most advanced filter materials does not ensure complete purification of milk from mechanical, much less bacterial, inclusions. At the same time, the surface of the filter quickly becomes contaminated with a layer of impurities, which leads to an increase in the number of bacteria in the milk passing through such a contaminated layer. In case of prolonged use of the filter, the remaining organic impurities decompose and sharply increase the microbial flora.

Recently, disposable paper filters have become widespread. They are easier to operate and provide better milk purification.

A much more advanced way of filtering and purifying milk is centrifugal purification. In this case, the milk is cleared not only of mechanical inclusions, but also of mucus, epithelial clots and blood that appear in the milk due to udder disease. Unlike filtration, during centrifugal cleaning, milk does not wash away contaminants that are deposited in the mud space of the purifier.

For farm dairy and milk processing enterprises, the industry produces centrifugal separator-cleaners of various standard sizes according to productivity. They are distinguished by high throughput, reliable operation, and provide high quality milk purification.

Machines and equipment for primary milk processing. Types and general assessment of milk purification - concept and types. Classification and features of the category "Machines and equipment for primary milk processing. Types and general assessment of milk purification" 2017, 2018.

The most common method of milk purification on farms is filtration. There are a large number of varieties of filters, the working elements of which are cotton pads, gauze, flannel, paper, metal mesh, synthetic materials, etc.

Cotton pads with a smooth or “waffle” surface, they clean milk well and do not require special care. Used cotton pads are replaced with new ones.

Slow filtration of milk through such filters requires increasing the capacity of the filter chamber.

Gauze filters usually used on farms. However, such filters quickly wear out, become dirty and do not provide a high degree of milk purity.

They are increasingly used on farms filters made of paper and synthetic fabrics(enanth, lavsan, etc.). When used correctly, 1 m of lavsan filter cloth replaces 40 m of gauze. Disposable paper filters, compared to reusable filters, allow you to obtain milk with less mechanical contamination.

Strainers used for filtering milk supplied in portions. They help smooth the flow of filtered milk

1 - frame; 2 - spacer ring; 3 - mud chute; 4, 6 - gratings; 5 - filter element

Rice. 18.7. Cylindrical filter:

1 - ring; 2 - filter element; 3 - frame; 4,6 - sealing gaskets; 5 - frame; 7 - adapter; 8 - screw

walls of the grid into a groove, from where they are removed when washing or replacing the filter. Cylindrical filter used for filtering milk in the flow of milking machines. This filter is a cylindrical element made of stainless steel. Inside the case 3 (Fig. 18.7) the filter has a frame 5, onto which a filter element 2 is placed, secured with a rubber ring 1. The filter is sealed in the housing by rubber gaskets.

The filter works as follows. Milk flowing through the milk line enters the filter housing, seeps through the filter material, on which mechanical particles settle, and enters the cooler. Before circulation washing, the filter element is removed from the filter housing.

To filter milk in high-performance milk lines, conical and disk filters are used, both single and yi in pair performance

50b.7.20bo6dm 3 /h.

Conical filter consists of a body 3 (Fig. 18.8), which is equipped with a supply 8 and 7 outlet pipes, as well as a cover 2 with valve 1 to release air. A milk collecting cup is placed inside the body 4 with filter element 5, the working element of which is lavsan. To disconnect the filter during its washing and cleaning, a tap is installed on the outlet pipe 6.

Sealing seal

The lid is reached by a rubber cord of rectangular cross-section placed in the groove of the lid. To the core

Rice. 18.8. Conical filter:

1 - valve; 2 - lid; 3 - frame; 4 - milk collection bowl; 5 - filter element; 6 - drain cock; 7, 8 - pipes

The lid is secured using special cap nuts.

Milk through the spigot 8 enters the filter housing, leaks through the filter element 5 and exits the filter through the tap into pipe 7. As sediment accumulates on the filter fabric, the throughput of the filter decreases.

The duration of continuous operation of conical filters, depending on the contamination of milk, is 3...4 hours. Once the filter element is clogged, stop operating the filter and replace the filter cloth. For a continuous process, two alternately operating filters are installed in the milk line, located in parallel and connected by a three-way valve.

Disc filters differ from conical and other designs by a developed filter surface, which can be adjusted by a set of disks 2 (Fig. 18.9), covered with filter elements 1 and secured with stoppers 3.

The duration of non-disassembly operation of filters of this design is slightly lower than conical ones, and for a single version it is 2...3 hours.

Most convenient for milk purification in a production line centrifugal cleaner, which, unlike filters, does not require replaceable filter materials.

The centrifugal cleaner consists of the following main components: drum 7 (Fig. 18.10), drive mechanism 2, receiving and output device, electric motor and frame 1.

Two -*■ brakes are installed in the Ostannina bowl of the drive mechanism Zddya quick stop of the drum after turning off the electric motor, as well as two stoppers 9, keeping the drum from arbitrary rotation during disassembly and assembly. The base of the drum is secured to the spindle of the drive mechanism using a shaped nut 5.

Rice. 18.9. Disc filter:

/ - filter element; 2 - disk; 3 - stopper

Rice. 18.10. Centrifugal cleaner:

I- bed; 2 - drive mechanism;
) - brake; 4- frame bowl; 5- nut
drum mounts; 6 - outlet pipe
yes milk; 7- drum; 8 - clamp; 9-
stopper; 10 - oil filler plug;

II- pulsator; 12 - level indicator

oils; 13 - oil drain plug

The receiving and output device is attached to the casing with a nut, and the casing to the frame bowl - with clamps 8. The drive mechanism is located in a frame, the oil bath of which has holes for filling and draining oil, which are closed with plugs, respectively. 10 And 13. The oil level is controlled by a gauge 12, and the number of drum revolutions is a pulsator //. The main working part of a centrifugal cleaner is the drum. Based on it 8 (Fig. 18.11) a plate holder is installed in a special groove 1, the position of which is fixed with a pin 9.

The outer surface of the plate holder has three slots on which a package of intermediate conical plates is placed 2. For ease of assembly, all plates in the drum are numbered. A separating plate is placed on the package of intermediate plates 3. The top of the drum is closed with a lid 4, which comes with the plate 3 forms a pressure chamber.

The tightness of the drum between its base 8 and lid 4

seal is provided -
ring 6. Position
cover relative to base
It is fixed with key 7.
■ 2 To connect the cover to the base

With? 4 The key is nut 5, I have

Rice. 18.11. Cleaner drum:

1 - plate holder; 2 - a package of plates;

3 - separating plate; 4 - lid;

5 - screw; 6 - sealing ring; 7 -

key; 8 - base; 9- pin

Rice. 12.18. Technological scheme of centrifugal cleaning:

1 - pressure disc; 2 - dishes; 3 - mud chamber

It has a left-hand trapezoidal thread, which eliminates the possibility of the nut self-unscrewing during operation.

The drive mechanism consists of a horizontal shaft connected to a vertical spindle shaft by a screw pair. Rotation of the horizontal shaft from the electric motor is transmitted through a friction clutch, which ensures gradual acceleration of the drum to operating speed.

The technological flow diagram for cleaning is shown in Fig. 12.18. Milk

through a throttle installed at the outlet of the pump with a given capacity, it enters the central tube of the drum, and then into the lower part of the plate holder and is discharged to the periphery of the drum. Under the influence of pressure, milk passes through the gaps between the plates from the periphery to the center.

By centrifugal forces developed in the drum, heavy particles (mechanical impurities) are thrown towards the walls of the drum, forming a dense sediment on them, which is removed from the drum after stopping.

The purified milk is forced to the center of the drum and enters the pressure chamber, where it is captured by the stationary disk of the outlet device and fed for further processing (pasteurization, cooling).