Installation for pasteurization and cooling of milk. Pasteurizing and cooling plants
Automatic pasteurizing and cooling plants Normit Paster 3000 and 5000 l/h
The pasteurization plant is mounted on a frame and is delivered ready for operation.
Commissioning takes only 1-3 days.
The plant is completely made of steel AISI 304/316 and/or higher. Productivity on milk: 3000-5000 l/hour. It is intended for the production of heat-treated dairy products in the most gentle way in order to obtain high-quality products without destroying protein, milk sugar and fat molecules.
Fully automated and equipped with flow rate control, the unit varies the product flow depending on the performance of the separator and fat normalizer.
Product and heating water temperature sensors provide delta T control to prevent protein breakdown at varying pasteurization rates and temperatures. 
The unit is equipped with pressure and temperature control and diverter valves in accordance with the latest EC Hygiene Directives, as well as temperature and event archiving.
The control is based on Siemens PLC with touch panel. It only needs to be connected to water, steam, electricity, sewerage, and to the inlet/outlet of milk and CIP. The unit is supplied as a complete assembly, which is shown in the attached process flow diagram. All plate heat exchangers, pumps and valves manufactured by Alfa Laval. Flow sensors, level controllers from Endress+Hauser, other sensors - IFM.
General control based on Siemens PLC. Heat exchanger plates - stainless steel AISI316 or 
higher. Max pressure- 10/13 bar.
POU warns
mixing of unpasteurized and pasteurized product thanks to tight differential pressure control.
The minimum differential pressure is 0.5 bar. Functions and protective systems comply with EU hygiene requirements.
The pasteurization plant consists of the following basic elements: 1 Pasteurizer with a capacity of 3,000 - 5,000 l/h, including 2 regeneration sections, 1 pasteurization section and 1 cooling section.
The outlet between regeneration sections 1 and 2 is for the separator/bactofuge/homogenizer.
The pasteurizing and cooling plant is used to pasteurize and cool fermented milk products. In other words, this installation is necessary for all enterprises that work with this category of goods. In addition, this unit is equipped with an automatic temperature control and regulation system, which makes its use even more convenient.
Installation description
To date, there are tubular and plate installations. Next, the device of the second type of such devices will be described. So, a plate pasteurization and cooling unit consists of such basic elements as:
- plate heat exchanger;
- a system designed for the preparation of hot water (it includes a pump, an injector and a convection type tank).
The main purpose of this system is that it heats the products to the fermentation temperature. There is also a pump for the products themselves. Naturally, since there is an automatic system for monitoring and regulating parameters, there is also a control panel for this system. It is important to note that the pasteurization-cooling unit is quite compact and made in a modular style. The only thing is the holder, which is a separate structural element. Regarding installation, it can be mounted in any available location. The result is a convenient system that has everything you need for automatic operation, which at the same time takes up little space.
Purpose of installation
The pasteurization-cooling unit is designed to perform such actions as:
- Heating of the dairy product to a temperature of 55-60 degrees Celsius (separation temperature).
- Heating to a temperature of 75-80 degrees (milk homogenization).
- Heating up to the pasteurization temperature of the dairy product - 90-95 degrees.
- The equipment also holds the product at its pasteurization temperature for 300 seconds.
- The last operation is cooling the product to the fermentation temperature, that is, up to 20-50 degrees.
Purpose of elements
The plate milk pasteurization and cooling unit is also capable of handling liquid products such as beer, juice, wine, beverages, alkalis, and others. A plate heat exchanger is responsible for heating and cooling these products. All operations are carried out with a closed stream. It should also be noted that due to the high thermal efficiency of such heat exchangers, they have a compact size. As for the efficiency, for all installations made on the basis of this model, it is more than 90%. All parts of the pasteurization-cooling plant that come into contact with food during operation are made of steel approved for use in the food industry.
The coolant in such systems is either water or brine. The heat carrier can also be water or steam. The device has which consists of plates, a bed and a pressure plate. All these parts are tied together with fixing pins.
Technical characteristics of the installation
The pasteurization and cooling plant for milk has a certain number of technical parameters, which vary depending on the model. Next, the parameters of the PBK-1 product will be described.
The first and most important parameter is, of course, performance. For this equipment, it is in the range from 1000 to 10,000 l / h. The next parameter is the temperature of both the coolant and the coolant in the system. The difference between the outgoing products and these carriers is from 2 to 4 degrees Celsius at a factor of 1/3. All models also differ in their dimensions, but not too much, and the parameter itself is not very important. The material used to make the plate is steel grade 12X18H10T. The thickness of the plates is 0.6 mm. The maximum temperature for PBK-1 is 150 degrees.
The principle of operation of the pasteurization-cooling plant
In an automatic plate-type system, the workflow is as follows.
At the factory, there is a milk collector, which is connected to the surge tank of the device. From the collector to this module, the products come either by means of a pump or by gravity. Here it is important to ensure that the milk level does not fall below 300 ml, otherwise air will begin to leak into the milk pump. The pump then pumps the product to the first section of the heat exchanger. Here, the dairy product is heated, as there is a heat exchange with hot milk following from the pasteurization section, through the holder. Here the temperature of the object rises to about 47-50 degrees Celsius, after which the milk is pumped through the purifier into the second section. Here the product is reheated. The heat exchange takes place with the same pasteurized milk that has undergone preliminary type heat exchange in section number 1. After this procedure is completed, the milk enters the pasteurization section, which is considered the third. Here, the heat carrier is already ordinary water. The heat exchange lasts until the dairy product is heated to 76 degrees Celsius.
Further, as described above, pasteurized milk returns through sections 1 and 2, where it gives off heat, thereby cooling to 20-25 degrees. After that, the products are pumped into the cooler, where the temperature drops to 5-8 degrees. The fully chilled milk is then fed into the storage tanks. This completes the work of the pasteurization and cooling plant for milk.
Tube type installation
The description above concerned a plate-type device, but there is also a second one - a tubular one. Such devices consist of a tubular apparatus, two centrifugal pumps, a non-return valve, condensate removal units, as well as a control panel designed to control automatic control and monitoring devices.
Description of the unit elements
The tubular pasteurizing and cooling unit includes in its composition It consists of two cylinders, upper and lower, which are interconnected by means of a pipe system. Tube sheets are welded into the ends of these cylinders, each of which contains 24 pipes with a diameter of 30 mm. The gratings are made of stainless steel and have short channels. These channels connect all 24 pipes. The result is a continuous coil with a total length of about 30 m. The cylinders, in turn, are closed with covers, which are equipped with rubber seals. This is done not only to create a completely sealed structure, but also to separate the short channels from each other.
In the operation of the device, there is steam, which, upon admission, enters the space between the cylinders. After it has worked, it is removed from the device in the form of condensate using thermodynamic type steam traps.
The essence of the unit
The milk to be heated moves in turn through the upper and then the lower cylinder. It moves along the intratubal space. The unit also has a valve that regulates the steam supply. It is located immediately at the entrance of this substance. At the outlet of the device there is another valve, but of a return type. It works in automatic mode, and its main purpose is the return of under-pasteurized milk for a second operation. To perform this function, the mechanism is connected to a temperature sensor through a device such as a temperature controller, which is also located at the milk outlet. Since the device has steam and milk pressure, the unit also has several pressure gauges.
It is worth noting that the processing starts from the lower cylinder, where there is steam, which heats the milk to a temperature of 50-60 degrees. The milk enters the lower part under the influence of the first centrifugal pump. For pumping to the upper one, a second pump is used. In the upper part, pasteurization of the substance is carried out to a temperature of 80-90 degrees Celsius.
The main advantages of the installation
This equipment has become widespread, as it stands out for a number of significant advantages that are important for this industry. Firstly, the device fully complies with thermal conditions both during pasteurization and cooling. At the same time, the specified performance is maintained. Secondly, the design of the modular type minimizes the size of the device, which makes it compact and, therefore, convenient for placement and use.
Milk and dairy products are pasteurized in special containers, tubular pasteurization units, as well as in plate pasteurization-cooling units.
The first include long-term pasteurization baths and universal baths.
The tubular pasteurization plant (Fig. 5.24) consists of two centrifugal pumps, a tubular apparatus, a check valve, steam traps and a control panel with process control and regulation devices.
Rice. 5.24. Tubular pasteurization plant: 1 - centrifugal pumps
for milk; 2 – steam traps; 3, 4 - branch pipes for condensate drainage;
5, 6, 7, 8 - milk pipelines; 9 - return valve; 10 - control valve
steam supply; 11 - safety valves; 12 - steam pipeline; 13 - pressure gauges
for steam; 14 - branch pipe for the exit of pasteurized milk; 15 - pressure gauge
for milk; 16 - control panel; 17 - upper drum; 18 - lower drum;
19 - frame
The main element of the plant is a two-cylinder heat exchanger, consisting of the upper and lower cylinders connected by pipelines. Tube sheets are welded into the ends of the cylinders, in which 24 pipes with a diameter of 30 mm are expanded. Stainless steel tube sheets have milled short channels that connect the ends of the pipes in series, thus forming a continuous coil with a total length of about 30 m.
Steam is supplied to the annulus of each cylinder. The exhaust steam in the form of condensate is discharged using thermodynamic steam traps.
Heated milk moves in the inner tube space, passing successively the lower and upper cylinders. A control valve for steam supply is installed at the steam inlet, and a return valve is installed at the milk outlet from the machine, with the help of which underpasteurized milk is automatically sent for re-pasteurization. The return valve is connected through a temperature controller with a temperature sensor located also at the milk outlet from the machine. The unit is equipped with pressure gauges to control the pressure of steam and milk.
The processed product is fed from the storage tank with the help of the first centrifugal pump to the lower cylinder of the heat exchanger, where it is heated by steam to a temperature of 50...60 °C and passes into the upper cylinder. Here it is pasteurized at 80...90 °C.
The second pump is designed to supply milk from the first cylinder to the second. It should be noted that in tubular pasteurization plants, the speed of movement of various products is not the same. In the installation for pasteurization of cream, the speed of their movement in the pipes of the heat exchanger is 1.2 m/s. In the process of heat exchange, the cream enters the pasteurizer cylinders with the help of a single centrifugal pump. The speed of milk movement as a result of the use of two pumps is higher and amounts to 2.4 m/s.
The advantages of tubular pasteurization plants in comparison with lamellar ones are a significantly smaller number and dimensions of sealing gaskets, and the disadvantages are large dimensions and high metal consumption; in addition, when cleaning and washing these installations, free space is required on the side of the ends of the cylinders of the heat exchanger.
Tubular installations are effective if the subsequent milk processing process is carried out at a temperature slightly different from the pasteurization temperature.
Pasteurizing and cooling plants used for heat treatment of milk, cream and ice cream mixture. The design of each of these installations has its own characteristics, which are reflected in the description of equipment for the production of various dairy products (Fig. 5.25).
Pasteurization-cooling units operate in the mode of short-term pasteurization at 75...76 °C with exposure of heated milk for about 20 s in a tubular in-line hold.
Raw milk flows from the tank into an equalizing tank, where a constant level is maintained by a float regulator. The pump delivers milk through the flow stabilizer to the section of the plate apparatus, through which the milk, heated to 60 ... 62 ° C, exits to one of the centrifugal cleaners. Purification of milk before pasteurization increases the efficiency of the pasteurizer and is one of the conditions for reliable pasteurization. It protects the plates of the pasteurizing section from premature formation of sticking, which reduces the heat transfer and performance of the apparatus.
Rice. 5.25. Scheme of the OPF-1 installation: 1 - lamellar apparatus;
2 - separator-milk cleaner; 3 - centrifugal pump; 4 - surge tank; 5 - bypass valve; 6 - holder; 7 - hot water pump;
8 - boiler; 9 - injector; 10 - control panel; I - section of the first regeneration;
II - section of the second regeneration; III - pasteurization section; IV - section of the water
cooling; V - brine cooling.
Semi-hermetic cleaners have a defoaming effect. They trap and break down the milk foam so that it does not enter the pasteurization section. Foam contributes to the formation of sticking and makes it difficult to warm all the milk particles to the pasteurization temperature. The cleaner has a pressure disc that plays the role of a centrifugal pump. Under its action, the milk passes through the pasteurization section, in which it is heated to 74 ... 76 ° C with hot water coming from the boiler. The cooling of pasteurized milk takes place in the regenerative, water and brine sections.
In the pasteurization-cooling unit UOM-IK-1, in addition to the holding sections and the plate heat exchanger, there is an infrared electric heating section. It consists of U-shaped quartz glass tubes with anodized aluminum reflectors. There are 16 tubes in the section (10 main tubes, 4 regulating the heating mode and 2 additional tubes), on which a nichrome spiral is wound. The tubes are connected to the network in parallel.
Rice. 5.26. Scheme of the pasteurization-cooling unit UOM-IK-1.
1 - section of infrared electric heating; 2 - holder;
3, 15 - thermometers; 4 - viewing area; 5, 6 - three-way valves; 7 - cooling section with ice water (brine); 8 – water cooling section; 9 - section
regeneration; 10 - manometer; 11 - plate heat exchanger; 12, 13 - valves; 14 - inlet valve; 16 - resistance thermometer; 17 - crane;
18 - surge tank; 19 - pump; 20 - washing tank; 21 - a container for storing milk.
The holder consists of two stainless steel tubes connected in series.
The plate heat exchanger has a regeneration section and two cooling sections.
Milk enters the surge tank and from it is pumped sequentially to the regeneration, infrared heating and holding sections. After the aging process, the pasteurized milk passes through a regeneration section, transferring heat to cold milk, and successively passes through water and brine cooling sections.
Plate pasteurization-cooling units have a number of advantages compared to other types of thermal devices:
· low working capacity, which allows automation devices to more accurately monitor the progress of the technological process (in a lamellar plant, the working capacity is 3 times less than in a tubular unit of the same capacity);
the ability to work efficiently enough with a minimum thermal pressure;
Minimum heat gain and loss of heat and cold (thermal insulation is usually not required);
significant savings (80-90%) of heat in the regeneration sections (the specific steam consumption in plate-type installations is 2-3 times less than in tubular ones, and 4-5 times less than in capacitive heat exchangers);
· small installation area (a lamellar installation occupies about 4 times less surface than a tubular installation of the same capacity);
the ability to change the number of plates in each section, which allows you to adapt the heat exchanger to a specific technological process;
Possibility of in-place circulating washing of equipment.
The highest technological indicators among domestic plants are possessed by modular automated pasteurizing and cooling units with electric heating of the Potok Term 500/1000/3000 type.
A feature of these units is a high heat recovery coefficient (0.9), an electrically heated hot water preparation system and a four-section plate heat exchanger (two regeneration sections, a pasteurization section and a cooling section). In the latter, rubber gaskets are made of a proprietary material and are connected to the plates with special clips, i.e. without the help of glue.
Rice. 5. 14. Technological scheme of OPU-3M
1 - heat exchanger; 2 - pump for hot water; 3 - boiler;
4 - injector; 5 - tubular holder; 6 - control panel;
7 - valve for automatic return of underpasteurized milk;
8 - tank; 9 - pump for milk; 10 - intermediate tank;
11 – flow stabilizer; 12 - pump; 13 - pasteurization section;
14 - regeneration section; 15 - section of water cooling;
16 - section of brine cooling; 17 - milk cleaner
Cooling - pasteurization plant OPU - 3U is designed for centrifugal cleaning, thin-layer pasteurization of milk in a closed stream and its subsequent cooling.
Each unit includes: plate pasteurizer-cooler, surge tank with float, milk pumps, flow uniformity regulator, separators - milk cleaners, automatic valve for removing underpasteurized milk, water heating boiler, steam injector, hot water pump, control panel with holding and steam and brine pipelines with pressure and flow regulators.
The sections of the installation differ in different arrangement of plates, their type and location. The plant has five sections: pasteurization, regeneration (stages I and II), water cooling and brine cooling. The work of the lamellar automated pasteurization-cooling plant is carried out as follows. Raw milk from the tank is pumped into the intermediate tank. The level of milk in the tank is maintained by a float device. From the tank, the milk is pumped by pump 12 through the flow stabilizer 11 to the regeneration section of the lamellar apparatus, where it is heated with pasteurized milk. Then the milk goes to alternately operating milk cleaners 17. The purified milk is fed under pressure to the pasteurization section of the plate apparatus, in which it is heated with hot water to a temperature of 76 ± 2 0 C and then sent to the tubular holding 5 and then to regeneration section 14. When the pasteurization temperature is below the set one, the milk is automatically returned to the tank 10 by an automatic valve for re-heat treatment. At a predetermined pasteurization temperature, milk from holding tank 5 sequentially passes sections 15 and 16 of water and brine cooling of the plate apparatus, being cooled to 4 ± 2°C. Water for the pasteurization section is heated in the injector 4 and supplied by water pump 2.
Technical specifications:
Productivity, l/h 3000
Temperature, 0 С:
Pasteurization 76 ± 2
Chilled milk 4 ± 2
Steam consumption, kg/h 72
Coolant consumption 9000
Working pressure 1.5
steam, MPA
Installed capacity
electric motors, kW 16.5
Overall dimensions, mm:
Length 2015
Width 700
