RU2457676C1 - Milk pasteurisation-refrigeration unit - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: invention relates to agriculture. Milk pasteurisation-refrigeration unit includes a thermally insulated rectangular tank with a slot evaporator which is built into the four sides, a gear motor with a mixer on the top cover, a compressor-condenser unit to the first magnetic actuator and a solenoid valve which is connected by pipes of pumping and suction with the inlet and outlet of the slot evaporator, a suction pressure sensor connected to the first magnetic actuator, and a sensor of reservoir temperature connected with its output with the solenoid valve and the first magnetic actuator. The unit has a flat welded hermetic tray with pressure and drain pipes, riser leg, welded reinforcing ties and water heating heating element, which is built into the bottom of the tank, as well as the cooling solenoid valve and a second magnetic actuator. Pressure pipe via the cooling solenoid valve is connected to the water supply, and drain pipe - through the riser leg - with sewage. The output of the temperature sensor is connected to the second magnetic actuator connected to heating elements as well with a cooling solenoid valve.

EFFECT: invention reduces the weight and size characteristics, reduces costs, water and energy consumption, increases coefficient of efficiency.

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Description

The invention is applied in agriculture and is intended for the daily collection of 1000 ... 3000 liters of milk from individual farms (IFC), its subsequent pasteurization, cooling and shipment of cans to catering points or packaging for the retail network. It is installed in village milk collection points, it is mainly used in combination with packaging machines to sell packages of pasteurized milk through a retail network, which allows you to double and triple the IFC's proceeds from small-scale livestock farming.

Dairy pasteurization-refrigeration units are known on applications for invention No. 2009144351 with a decision on the grant of a patent dated 12/08/2010 [1], as well as on patents RU 2396746 C1 dated 05/08/2009 [2] and RU 2388217 C1 dated 01/23/2009 [3] intended for pasteurization (warming up to 76 ° C) and subsequent cooling of milk before shipment by consumers or before packaging.

They contain a thermally insulated rectangular tank with a slit evaporator built into the bottom [2] or sides [1], a geared motor with an agitator on the top cover (traverse), a condensing unit connected by discharge and suction pipelines with an inlet (injector) and an outlet (collector) slotted evaporator. After pasteurization during cooling, liquid refrigerant is injected into the injector, evaporated from the collector is aspirated, which cools the milk from 36 ° C to 4 ° C.

Milk is heated from a water tank with heating elements through a slotted water jacket integrated respectively in the bottom [1] or sidewalls [2], or directly through disk heating elements pressed against the sidewalls [3]. Since cooling of pasteurized milk with a temperature of + 76 ° С by a slit evaporator due to boiling of freon is not possible, due to a critical increase in boiling pressure to 35 atm, then pasteurized milk is pre-cooled to 36 ° С initially by circulating tap (artesian) water through a slotted water jacket [1, 2] or through an immersion coil heater-cooler [3]. The disadvantage of heating milk through disk heaters is the design complexity and a large number (30 pcs.) Of one-kilowatt disk heaters ⌀160 mm for the timely heating of large volumes of milk. 30 heating elements have a contact surface of the order of 0.4 m ² and heating milk to 76 ° C leads to a burning of fat from milk in the corners of the tank, where the flow rate of the layers from the mixer is limited. In this case, the inner surface of the tank wall overheats to 120 ° C, which sometimes leads to boiling and burning of fat. The contact surface of the slit water jacket according to the patents [1, 2] is five times larger, which eliminates burning and reduces water overheating to 90 ... 95 ° C at the end of pasteurization (+ 76 ° C in milk), however, their drawback is also a significant design complexity, requiring a water tank with six to nine 5 kW heating elements, as well as an additional electric pump and two to four electromagnetic valves.

On the other hand, thermally insulated pasteurization baths of 1000 L of milk G2-OPB-1000 are known, described on the website www.deltamol.ru [4]. They contain a geared motor with a stirrer, a sealed annular cavity around a vertical cylindrical bath with milk, into which at first an hour and a half hot steam of 95 ° C is supplied with a flow rate of 150 kg, and then ice water + 2 ° C with a flow rate of 5 cubic meters. in hour. Flows are regulated by complex electro-pneumohydroautomatics, such energy and refrigeration supply is available only at large and medium-sized dairies and cannot be used in the conditions of a Russian village. OGU-2.5 domestic universal plate pasteurization and cooling units with a capacity of 2500 l / h are also known, described on the site www.protex.ru [5] and German installations for full pasteurization of milk with a capacity of 5000 l / h, described on www.trubatec.org . [6]. They heat milk with hot steam through plate heat exchangers, and then cool pasteurized milk with ice water, through the same multi-section plate heat exchangers. The exposure time of the milk flow during heating to 78 ° C is 25 s, then cooling to 4 ° C. Installations contain a complex integrated control system, hydropneumatics, a lot of milk pumps, flow meters, additional heat exchangers, electromagnetic pneumatic and hydraulic valves, programmable industrial controllers.

They have increased productivity, power in terms of steam and ice water consumption, large weight and size characteristics and high price, which is available to large small-scale commodity farms, but makes their use directly in villages unacceptable.

Also known are pasteurization dairy workshops KOLAKS-1001 per 1000 liters per day, described on the website www.solaxm.ru [7], containing a vertical cylindrical bath of long pasteurization per 500 liters of milk ⌀800 mm, N 1000 mm with an annular tight cavity around the inner tank for supplying steam or hot water, as well as a tank-electric heater of 120 l with a power of 25 kW for heating. In addition, the workshop contains a plate cooler with a water consumption of 3 m ³ per shift at a temperature of not more than 6 ° C for cooling with artesian or ice water. The warm-up (pasteurization) time of 500 liters of milk is about 4 hours.

The disadvantage of the KOLAKS-1001 equipment is the small heat exchange area with partial filling of the tank, which slows down the process of long-term pasteurization of milk when filling up to 50%. In fact, the process uses three heat-exchange tanks: a long pasteurization tank, a water tank and a plate cooler, as well as one storage tank of the finished product per 1000 l of milk, which complicates electro-pneumatic automation, reduces efficiency, increases overall dimensions and cost, while all tanks need thermal insulation to reduce the loss of cold and heat.

In addition, a decrease in the temperature of cooling water (not more than 6 ° C), due to the need to cool the outlet temperature of pasteurized milk, involves an external refrigerator or artesian water, which imposes additional problems when installed in unequipped places. The consumption of cold (ice) water will also be increased (three times) when the milk is gradually brought to the required temperature + 4 ° C, taking into account 3 cubic meters per 1000 liters of product, due to a decrease in the heat pressure (temperature difference) between the milk and the cooling water at the end of the process . Periodic maintenance (rinsing) of the plate cooler is also complicated by the need to monthly remove milk stone and fat associated with the passage of large volumes of milk through the cavity of the plate heat exchanger, which requires frequent mechanical disassembly of the plates and cleaning. In arid regions, drilling an artesian well is not always possible, and it costs at least 1 million rubles. There is also known a useful model of a square bathtub of long pasteurization for milk fermentation [8] according to patent RU 2007139028 of 23.10.2007, containing water heating elements in a heat-exchange water jacket for heating, built-in in the bottom. The cooling of the fermented reservoir with milk after pasteurization is carried out by tap or artesian water by passing it through an airtight cavity (water jacket) and an overflow pipe. To exclude “crushing” of the tank and “swelling” of the sealed cavity, the dynamic pressure in it is limited by a throttle washer with a diameter of ⌀3.5 ... 5 mm at the inlet pipe. At the same time, this washer reduces the flow rate of cold water through the cavity to 30 ... 50 l / min and proportionally limits the cooling rate. In addition, it does not fully protect the tank from “crushing” when the overflow pipe becomes clogged, when the pressure in the cavity can reach 3 ... 5 atm (water value).

The closest known by technical nature to the proposed invention (prototype) is a milk pasteurization-refrigeration unit according to the application for invention No. 2009144351 of November 30, 2009 with a decision on the grant of a patent of December 8, 2010 [1].

It contains a thermally insulated tank with a gear motor, a stirrer, a milk temperature sensor, a slit evaporator in four sides and a water jacket in the bottom, as well as a water heating tank (VNB) with heating elements, an electric pump, pressure and drain solenoid heating valves, and a condensing unit (KKA) ) with a solenoid valve, pipelines connected with a slotted evaporator of the sidewalls. Pasteurized heating of milk is carried out using an electric pump by circulating water from the WSS through a slotted water jacket, and pre-cooling of pasteurized milk from 76 ° C to 34 ° C (by the time the freon cooling is connected from the CCA) is carried out through tap (artesian) water poured through the slotted water water shirt down the drain.

The main disadvantage of the prototype is a significant complication of the design in the form of an additional thermally insulated water heating tank, electric pump, a number of pipelines, many electromagnetic and other valves, three magnetic actuators, combined with an increase in overall characteristics, which increases their cost.

The aim of the invention is to simplify and cheapen the design while increasing efficiency and reducing overheating of water as a coolant. For this purpose, in a milk pasteurization and refrigeration unit containing a thermally insulated rectangular tank with a slit evaporator integrated in four sides, a gear motor with an agitator on the top cover, a condensing unit with a first magnetic starter and a solenoid valve connected by discharge pipelines and suction with input and output of a slit evaporator, as well as a suction pressure sensor associated with the first magnetic actuator, and a tank temperature sensor associated with its output with a solenoid valve and a first magnetic actuator, according to the invention, a flat sealed pan with a pressure and drain nozzles, a lifting elbow, reinforcing welded couplers and water heating elements integrated in the bottom of the tank, as well as a cooling solenoid valve and a second solenoid through a pressure solenoid through the cooling valve is connected to the water supply, and the drain pipe through the lifting elbow is connected to the sewer, while the output of the temperature sensor is connected to the second actuator connected to TENam and cooling with an electromagnetic valve.

The invention is illustrated by drawings, where figure 1 shows the assembly drawing of the MPHU, and figure 2 is a combined electro-hydraulic circuit.

MPHU (figure 1, figure 2) contains a rectangular thermally insulated tank 1 with an outer lining 2, a layer of insulation 3 and a slotted evaporator 4, built into four sidewalls. The gear motor 5 with a stirrer 6 is located on the upper thermally insulated cover 7, sealed with an elastic sleeve 8. The cover 7 is closed for density by locks (not shown in FIG. 1) and opens when flushing with air springs 9. The cover 7 can also be made integral and contain motionless central traverse. The compressor-condenser unit (KKA) 10 with the first magnetic actuator 11 and the solenoid valve 12 is connected by pipelines forcing 13 and suction 14 to the inlet and outlet of the slit evaporator 4. On the frame of the KKA 10 there is a compressor 15, a condenser 16, a receiver 17, a filter 18, thermostatic valve 19 and suction pressure sensor 20.

With the bottom of the tank 1, having dimensions of 1290 × 1850 × 900 mm (WxDxH) for a nominal volume of 1,500 l, a flat tight pallet 21 is welded with a pressure head 22 and drain 23 nozzles, a lifting elbow 24, and also reinforcing welded screeds 25. The welded screeds 25 are made from a stainless steel pipe ⌀30 mm long 70 mm with end square "nickles" 50 × 50 mm (Fig. 1) and evenly reinforce the pan 21, withstanding the pressure of the water supply P = 3 at. At the ends of the pan 21 hermetically assembled water heating elements 26 (Fig. 1) with a capacity of 5 kW each of 9 pcs. for a capacity of 1,500 l of tank 1. This makes it possible to load each phase of 220 V into 15 kW uniformly symmetrically by a "star" with a total heater power of N = 45 kW. In the lifting elbow 24, which is actually a expansion tank ⌀100 mm, 200 mm high, there is a float level sensor 27. The discharge pipe 22 is connected to the water supply system 29 through the cooling electromagnetic valve 28. The drain pipe 23 is connected to the sewage system 30 through the lifting elbow 24. B a pan 21 is welded into a partition 31 with a length of 600 mm for even distribution of the flow of cooling water. Heating elements 26 are connected to a three-phase industrial network 380 V through a second magnetic starter 32 (figure 2). A multifunctional milk temperature sensor 33 is mounted on the tank 1 and connected via its output through the pasteurization temperature comparator 34 t ° C = 76 ± 1 ° C to the second magnetic starter 32 and the cooling solenoid valve 28, as well as through the comparator 35 (temperature + 36 ° C, start of freon cooling) with the first magnetic actuator 11 and the solenoid valve 12. In addition, the temperature sensor 33 is connected to the solenoid valve 12 through the turn-off comparator 36 (+ 4 ° С, completion of the cooling process) 37 and through the turn-off comparator 37 (temperature + 20 ° С , completion of water pre-cooling) - with a solenoid valve 28.

MPHU works as follows.

When the pasteurization mode is activated, the second magnetic starter 32 connects the heating elements 26 to the industrial network 380 V, 50 Hz and starts heating the water in the pan 21. Through the bottom of the tank 1 with an area of the order of S = 2 sq. M, with a thickness of h = 1.5 mm, the heat is uniformly transferred to the milk. This is facilitated by a mixer 6, rotated by a gear motor, homogenizing the layers of milk and uniform heat removal. Due to the large area of direct thermal contact S = 2 sq. M between the water pan 21 and convection heat fluxes from the heating elements 26 directed upwards, as well as the operation of the mixer 6, the overheating of water relative to milk does not exceed several degrees. A simple calculation of the transmitted power N (kW) through stainless steel with a thickness of h = 1.5 mm with a thermal conductivity coefficient of K = 15 W m / deg with a temperature difference of ΔТ = 3 ° С, S = 2 sq.m, shows that

N = K ^∗ ΔT ^∗ S / h = 15 ^∗ 3 ^∗ 2 / 1.5 ^∗ 10 ^-3 W = 60 kW.

Thus, the calculated overheating does not exceed 3 ° C with a power flow of 45 kW. It is close to really measured. Thus, milk in 2 ... 3 hours heats up to 76 ° C without burning milk fat, overheating of heating elements and boiling water. The float level sensor 27 in the lifting elbow 24 protects the heating elements 26 from burnout in the event of an emergency depressurization of the pallet 21 by de-energizing them through a second magnetic actuator 32.

After warming up to 76 ° C, the comparator 34 is activated, de-energizes through the second magnetic starter 32 of the heating elements 26 and turns on the cooling electromagnetic valve 28.

170 l of hot water + 80 ° C from the airtight pan 21 is displaced through the overflow bend 24 by the water supply 29 to the sewer 30. Layers of warm water rise up and flow out through the drain pipe 23 located at the top of the pan 21, and a layer of cold water is fed into the discharge pipe 22 located at the bottom of the pallet 21. The partition 31 promotes uniform symmetrical distribution of the flow of cooling water over the entire plane of the bottom.

Reinforcing welded screed 25 provide the necessary margin of safety for the bottom of the tank 1 and the flat sealed pallet 21 and protect its cavity from “bloating” during an emergency pressure increase up to P = 3 atm, for example, when the sewage is clogged or iced up 30. The most stressed welding seam around the pipe is 25 ⌀ 30 mm, with the leg b = 2 mm has an area F = π ^* d ^{* b} = 180 mm² and a specific tensile stress σ = P ^{* S} / Fn = ^{3 * 2 * 10 4/180} * 9 = 40 kg / sq. mm, where n = 9 is the number of screeds 25. This voltage is maintained by the weld without breaking. Initially, the temperature difference ΔT between the pasteurized milk and the water supply is ΔT = 76-16 = 60 ° C. Due to this gradient, the flow of refrigeration power N increases sharply, essentially being limited by the flow of water through the electromagnetic valve 28. The mixer 6 promotes intensive heat transfer and cooling of the entire volume of milk. The bottom area S = 2 sq. M is quite enough for the water to come into the discharge pipe 22 cold 16 ° C, and flow out of the drain pipe 23 close to the temperature of the milk.

After almost half an hour, the temperature of the pasteurized milk drops to 36 ° C when the comparator 35 is activated, and the compressor 15 KKA 10 is turned on through the magnetic starter 11, and the solenoid valve 12 opens. The liquid freon from the receiver 17 through the filter 18, the solenoid valve 12, TPV 19 enters the slotted evaporator 4 of the sides of the tank 1. Evaporating, the freon cools the milk, then the vapors are sucked through the pipe 14, are compressed in the compressor 15 and condense in the condenser 16, coming back into the receiver 17 as a liquid.

There is an accelerated process of double cooling of milk - water through the bottom of the tank 1, and freon - through the slotted evaporator 4 of its sidewalls. The mixer 6 promotes intense heat transfer.

After another half hour, the milk is cooled to 20 ° C. The heat pressure between the pasteurized milk and tap water ΔТ decreases to ΔТ = 20-16 = 4 ° С, after which further pre-cooling of the milk with water becomes impractical, as it is accompanied by excessive discharge of water with a temperature of 17 ... 18 ° С to the sewage system 30. A shutdown comparator trips 37, the solenoid valve 38 is de-energized and the water flow is shut off.

Further after-cooling of milk in 1 hour is carried out only by freon from KKA 10. At the same time, expansion valve 19 automatically reduces the flow of liquid into the slit evaporator 4 as the heat load decreases, ensuring constant overheating. When the milk is cooled down to + 4 ° C, the shutdown comparator 36 is activated, which de-energizes and closes the solenoid valve 12. The residual liquid freon is evaporated from the slotted evaporator 4 and sucked out through line 14, then condensed into the receiver 17. When the pressure in the sensor 20 decreases to 0, 5 at, the first magnetic starter 11 is turned off and the compressor 15 is stopped. Such completion of the milk cooling cycle ensures the absence of liquid freon in the slit evaporator 4 and, accordingly, eliminates a critical pressure increase in the whole yvayuschem conduit 14, with the washing tank 1 with hot water or heating in the next cycle of pasteurization. Thus, in almost 4 ... 5 hours we have in the tank 1 1500 l of pasteurized and chilled milk. With a decrease in the initial loading of the tank 1, the milk processing time is proportionally reduced.

Compared with the prototype [1] and analogues [2, 3], the present invention has a significant simplification and reduction of overall dimensions and cost. Another advantage over the prototype is the increased contact area between milk and water due to the inclusion of radius flanges in the contact, which is impossible in a slotted water jacket [1]. Heat losses are eliminated at the WSS, pumps, pipelines, water overheating is reduced, boiling is eliminated, and efficiency increases. Compared with plate analogues [5, 6], the invention also significantly simplifies the design and maintenance, since washing the milk cavity of the tank 1 with hot water and solutions with the lid 7 raised on the air springs 9 and open locks does not present any problems. Compared with reservoir counterparts [4, 7, 8], the present invention allows to reduce the water consumption by several times and to cool the milk to + 4 ° C (SANPIN norms) by KKA 10. Since November 2010, the proposed MPHU with volumes from 1000 l to 3000 l were introduced into serial production at the enterprise NPP Avtomat-Vladimir LLC (Kovrov).

Bibliographic data

1. Milk pasteurization and refrigeration unit. Application for invention No. 2009144351 dated November 30, 2009 with the Decision on the grant of a patent dated December 8, 2010

2. Dairy pasteurization and refrigeration unit. Patent RU 2396746 C1 dated 05/08/2009

3. Dairy pasteurization and refrigeration unit. Patent RU 2388217 C1 of January 23, 2009

4. Bath pasteurization of milk G2-OPB-1000, website: www.deltamol.ru.

5. Universal plate pasteurization and cooling unit OGU-2.5, website: www.protex.ru.

6. Complete milk pasteurization unit 5000 l / h, website: www.trubatec.org.

7. Pasteurization dairy workshop KOLAKS-1001, website: wvvw.colaxm.ru.

8. Bath long pasteurization. Patent RU 2007139028 of 10.23.2007 for a utility model.

Claims (1)

A milk pasteurization and refrigeration unit containing a thermally insulated rectangular tank with a slit evaporator integrated in four sides, a gear motor with an agitator on the top cover, a condensing unit with a first magnetic starter and a solenoid valve, connected by discharge and suction pipelines with a slot inlet and outlet the evaporator, as well as a suction pressure sensor connected to the first magnetic starter and a tank temperature sensor connected by its output to the solenoid valve and the first magnetic actuator, characterized in that a flat welded sealed pan with pressure and drain nozzles, a lifting elbow, reinforcing welded couplers and water heating elements, built-in in the tank bottom, as well as a cooling solenoid valve and a second magnetic actuator, are introduced into it the pipe through the solenoid cooling valve is connected to the water supply, and the drain pipe through the lifting elbow to the sewer, while the output of the temperature sensor is connected to the second magnetic a starter connected to the heating elements, as well as with a solenoid cooling valve.

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