RU120541U1 - PASTERIZATION INSTALLATION - Google Patents

Abstract

1. Pasteurization plant containing a replenishment tank of raw milk with a centrifugal circulation pump and a return valve, a recuperative plate heat exchanger of counter flows of pasteurized and raw milk, a water-heating pasteurization tank with a screw coil, heating elements and an associated water thermostat, as well as a holding device with a temperature sensor the replenishment tank through the centrifugal pump and the inlet pipes of the heat exchanger (raw milk flow) is connected by pipelines to the inlet of the helical coil, and the outlet of the helical coil is connected through the holding tank and the return pipes of the heat exchanger (counterflow of pasteurized milk) by pipelines to the inlet of the return valve, the first outlet of which is connected to the replenishment tank, and the second outlet - with the outlet of the installation, while the temperature sensor is connected to the electrical inlet of the return valve, characterized in that the helical coil is made of a thin-walled pipe of at least 40 mm in diameter, and the holding device in the form of a sealed cylindrical tank with a quick-detachable end cap, in addition, a second temperature sensor is installed in the inlet of the return valve, which is also connected to its electrical input. ! 2. Pasteurization installation according to claim 1, characterized in that a replaceable throttle washer is installed in the outlet pipe of the centrifugal pump.

Description

DESCRIPTION.

Application area.

The utility model, pasteurization unit, hereinafter PU, is intended for heating (pasteurization) and subsequent cooling, mainly milk in the stream, as well as for pasteurization of beer, juices and can be used in food industry enterprises, dairies and dairy farms, when produced sour cream, cream, kefir, cottage cheese with production volumes from 3,000 to 30,000 liters per day.

The level of technology.

Currently, for pasteurization in a stream (heating to 76 ° ... 92 °) and subsequent cooling with a capacity of 1000 l to 2000 l per hour, devices based on a plate heat exchanger - a regenerator (recuperator) through which counter flows of raw (cold) are passed ) milk and pasteurized (hot) milk [1, 2, 3, 4]. The milk can be re-heated by heating elements with an electric boiler [1, 2, 3] through a coil, or by rotary (vortex) centrifugal pumps [4] by converting the mechanical energy of electric pumps into heat. The disadvantage of the latter is the high acoustic noise at a capacity of 1,500 l / h from two electric pumps (2 * 7.5 = 15 kW). The advantage of plate recuperative pasteurizers in a stream with an electric boiler is high efficiency and energy saving, and the disadvantages are the complexity of washing, the complexity of maintenance, the need for additional reservoirs of raw and pasteurized milk. Capacitive baths of long pasteurization [5] with heating elements and artesian water are free from these shortcomings. as well as pasteurization-refrigeration units [6] with heating elements, water pre-cooling and freon post-cooling. Pasteurization of milk up to 2500 l per shift and its cooling is carried out in a single tank [5, 6] up to 2500 l. There is no problem with its washing and maintenance, however, the drawback of direct heating of milk (without recovery) is its high energy consumption (0.1 ... 0.15 kWh per liter), although recuperative plate pasteurizers in the flow [1-4] can save up to 85% electricity and process up to 10,000 ... 30,000 liters of milk per shift.

Of the known pasteurization plants, the closest in technical essence (prototype) to the proposed solution is a device [1] for pasteurization IPKS-013R-2500R according to patent RU 2007146478, manufactured in Ryazan by Elf-4M, described in detail on the _ipks- website 013-01.pdf [2].

The device contains an equalizing (replenishing) raw milk tank with a centrifugal circulation pump and a check valve, a recuperative plate heat exchanger of counter flows of pasteurized and raw milk, a pasteurization water heating tank with a helical milk coil, heating elements and an associated water thermostat, as well as a pre-assembled holding coil 60 4 m long with 1.5 m rolls and a temperature sensor. In this case, the refill tank through the centrifugal pump and the inlet nozzles of the heat exchanger (direct milk flow) is connected by pipelines to the inlet of the screw coil, and the outlet of the screw coil through the collecting coil-cooler and the return pipes of the heat exchanger (countercurrent of pasteurized milk) are connected by pipelines to the inlet of the return valve associated with a refill tank, and - a second plate heat exchanger - aftercooler, fed by a stream of ice water - with the output of the device. The thermocouple of the coil - fuse is connected to the electrical input of the check valve. The device [1,2] provides a productivity of 1000 to 2500 l / h, a heat energy recovery level of up to 80%, a chilled product temperature of 4 °, a holding time of 16 ... 20 s with a consumption power of up to 46 kW, a pasteurization temperature of 76 ... 92 °. Daily washing of the device with alkali and acid in the circulation mode according to the Passport [2] takes 30% of its operation time. Once every three days it is recommended to disassemble the holding coil and pipelines (7 pcs.) With their cleaning with tampons and a flexible cable. Recuperative plate and second refrigeration heat exchangers must be disassembled and cleaned mechanically once every six months or as they become clogged and performance decreases.

And most importantly, it is not clear what to do in case of clogging with a screw milk coil made of a double F20 * 1 stainless pipe, 15 m long, 10 turns of F500. Apparently it needs to be protamped with a long fifteen-meter cable F3 ... 4 mm, which is problematic, or replaced. Thus, the disadvantages of the prototype should include the complex and overall design of a collapsible coil - stand, as well as a twin, long screw coil 2pcs * 20 * 1.0 pasteurization tank. Another disadvantage of the prototype is an excessive second plate heat exchanger for cooling pasteurized milk to + 4 ° C with ice water. This is not always necessary and does not allow to take advantage of recovery pasteurization. For example, for packaging whole milk, a temperature of 14 ° C is recommended, obtained at the outlet of the first (recuperative) heat exchanger. And for the separation of milk in the process of further processing (upon receipt of semi-fat cottage cheese, normalization of fat content of products to 1% MJ, 2.5% MJ, 3.2% MJ), it is required to have an optimum temperature of pasteurized milk 40 ... 42 ° C. Any VDP [5, 6] allows you to heat chilled pasteurized whole milk to 42 ° C and pass it through a separator, Zh5-OSB, but this is accompanied by inappropriate additional energy costs. The third disadvantage of the prototype is the increase in the number of plates, prices and dimensions in a regenerative plate heat exchanger with an increase in productivity from 1000 l / h to 2500 l / h, which is not always justified, because often a flexible change in productivity is required due to seasonal fluctuations in milk yield by 1.5 ... 1.8 times without a change in design.

The technical result.

The purpose and technical result of the proposed utility model is to simplify the design of the PU, reduce weight and size characteristics, simplify maintenance and periodic collapsible washing (cleaning) of the milk pipe, optimize the design of the screw coil of the pasteurization tank due to the “length-diameter” ratio, universalize the design of PU with simple seasonal adjustment productivity within 1000 l / h ... 3000 l / h, production of pasteurized whole milk with a temperature of + 14 ° (for packaging), or + 40 ° ( for separation) at the choice of the operator.

The technical nature of the device.

The claimed technical result is achieved by the fact that in a pasteurization installation containing a raw milk tank with a centrifugal circulation pump and a check valve, a recuperative plate heat exchanger of counter flows of pasteurized and raw milk, a pasteurization water heating tank with a helical coil, heating elements and a related water thermostat, and also a curing device with a temperature sensor, and the refill tank through a centrifugal pump and the inlet pipes of the heat exchanger (direct-flow crude milk) is connected by pipelines to the inlet of the helical coil, and the outlet of the helical coil is connected through pipelines and return pipes of the heat exchanger (countercurrent of pasteurized milk) to the inlet of the check valve, the first outlet of which is connected to the refill tank, and the second outlet to the outlet of the unit, the temperature sensor is connected to the electrical input of the check valve; according to the essence of the utility model, a helical coil is made of a thin-walled pipe with a diameter of at least 40 mm and a holder in the form of g a sealed cylindrical tank with a quick-detachable end cap; in addition, a second thermal sensor is also installed in the inlet pipe of the return valve, also connected with its electrical input. In addition, a replaceable throttle washer can be installed in the outlet pipe of the centrifugal pump.

A brief description of the drawings.

Figure 1 shows the circuit diagram of the PU.

The pasteurization installation contains a refill tank 1 of raw milk with sensors of the upper 2 and lower 3 levels, as well as a centrifugal circulation pump 4 and a check valve 5. The flows of raw cold milk and pasteurized hot milk pass counter-flow through a recuperative plate heat exchanger (RPT) 6, so that the output the nozzle of the centrifugal pump 4 through the throttle washer 7 is connected to the inlet pipe 8 of the RPT 6 of raw milk, and the outlet pipe 9 of raw milk from the RPT 6 to the inlet of the screw coil 10 of the water heater asterization tank (VPB) 11. Inside the screw coil 10 having a coil diameter D = 530 mm, pitch h = 60 mm, n = 4.5 turns, the total length of the pipe with terminations L = 8 m, TENs 12, 9 pcs are installed * 5kW = 45kW. The helical coil 10 is made of thin-walled stainless pipe Ф40 × 1 AISI316 steel. The outlet pipe 13 of the screw coil 10 through the holder 14 with a quick-release end cap 15 is connected by a pipe to the inlet pipe 16 of the RPT 6 of pasteurized milk. The outlet pipe 17 RPT 6 is connected to the inlet pipe 18 of the check valve 5, one outlet 19 of which is the output of the PU, and the other outlet 20 - returns the "cold" milk to the refill tank 1. The temperature sensor 21 "+ 80 ° C" of the soaking agent 14 is connected with the first the electrical input of the check valve 5. In the inlet pipe 18 of the check valve 5 is installed a second temperature sensor 22, also associated with the second input of the check valve 5.

Sustainer 14 is made in the form of a sealed cylindrical tank D = T90 mm, 1 = 500 mm, volume 14 l, so as to provide a holding time of pasteurized milk of at least 13 s at a maximum flow rate of 4000 l / h, as well as easy to rinse and clean the inner cavity with ruffs with the cover removed. RPT 6 is made of stamped plates of high-alloy AISI316 stainless steel with dimensions of 750 × 350 × 0.7, 23 pieces, an equivalent area of F = 6 sq.m, providing for a counter flow of 2000 l / h a temperature difference of no more than T = 10 ° C at the output and at the entrance.

PU works as follows. Using the heating elements 12 and a water thermostat (not shown in FIG. 1), the desired pasteurization temperature (80 ° ± 1 °) C is maintained in the VPB 11 water heating pasteurization tank. Raw milk + 4 ° С from level sensors 2,3 is pumped into the refill tank 1 from the refrigeration tank by an external pump as it is pasteurized. Raw milk passing through RPT6 is heated to 70 ° C, then in a screw coil 10 it is heated to a water temperature of 80 ° C and in cure 14 is held for at least 15 ... 20 s at this temperature.

The return flow of pasteurized milk through the RPT 6 is cooled from 80 ° C to 14 ° so that the temperature difference along the plates remains T = 10 °. To optimize the design parameters of the screw coil 10, it is necessary to calculate the heating of milk at a length of 1 to a temperature τ inside a pipe with a diameter of d = 40 mm, a thickness of h = 1 mm from AISI316 stainless steel with a thermal conductivity of k = 15 W / m * deg. The heat capacity of milk c = 3.9 kJ / kg * deg, density p = 1 kg / l, flow rate Q varies from 1200 l / h to 3000 l / h or from Q = 0.33 l / s to Q = 0.8 l / s using throttle washer 7 from 3 mm to 5 mm in diameter.

Moreover, from the technical characteristics of the mentioned RPT 6 it is known that in the steady state at flow rates Q = 0.57 l / s, 2000 l / h it has a temperature difference of counter flows T = 10 °, i.e. raw milk is warmed from 4 ° to 70 °, and pasteurized milk is cooled from 80 ° to 14 °. At the same time, an increase in the flow Q doubles the differential T to 20 ° C, reducing the recovery coefficient, and a decrease reduces T to 5 ° C, increasing the recovery. The desired pasteurization temperature (water temperature) is automatically set by the water thermostat and heating elements within (77 ° ... 92 °) ± 1 °.

The elementary increment of the thermodynamics of the thermal energy of milk ∂W in the steady state flow through the pipe d = 40 mm at a length ∂l is described by the partial differential equation

∂W = πd [k * (T-τ) / h] ∂l = Qcpdτ,

Where ∂τ is the elementary increase in milk temperature, πd∂1 is the elementary area (ring) of the pipe with a length of ∂l, thickness h = 1 mm, through which milk is heated. Whence we obtain T = (Qcph / kπd * ∂τ / ∂l + 1) τ, or

Where is the Laplace operator in partial derivatives, i.e. the increment of the temperature of milk along the length, ξ = Qcph / kπd is the constant of length [m]. The solution of this differential equation gives the following exponential dependence of the rise in milk temperature along the pipe

From this basic formula it follows that the temperature of the milk inside the coil pipe with its sufficient length l = 3ξ; 6ξ, increases from the initial T ₀ = 70 ° almost to the water temperature T ₀ + τ = 80 ° in the inverse exponent (1).

The length constant ξ for the mentioned pipe parameters at flow rates Q = 2000 l / h = 0.57 l / s gives the value ξ = Qcph / kπd = 1.2 m

Therefore, for a given flow rate, the length of the coil coil pipe L = 8 m = 6.5 ξ, exp (-6.5) = 0.002, is quite sufficient to warm the milk to water temperature. The analysis of the coil - the prototype [1] according to formula (1), which has a twin pipe half the diameter and the flow rate through each Q is also half reduced, shows the same constant ξ = 1.2 m, therefore its excess length L = 15 m = 13ξ is nothing , except for problems with cleaning, does not add for recovery, because even short 4-meter pipes make it possible to heat milk in the coil practically by the mentioned 10 ° to the water temperature. It should be noted that PU productivity growth, i.e. a double increase in costs to Q = 4000 l / h increases ξ to 2.4 m, however, the declared length L = 8 m according to the basic formula (1) provides the required heating of milk, because L = 3.2ξ, and [1-exp (-3.2)] = 0.97, i.e. the milk in the spiral coil 10 will be heated at τ = T * 0.97 = 20 * 0.97 = 19.4 ° C. Milk, heated in a helical coil, cools the water. For the energy balance of the steady state at nominal flow rates τ = Т = 10 °, Q = 0.57 l / s, a water thermostat with heating elements 12 will automatically supply an average power, maintaining the water temperature within 80 ± 1 °.

If we double the costs Q, without changing the recovery coefficient, determined by the RPT 6 parameter in the form of a temperature difference τ = Т = 10 °, which can be realized by doubling the number of heat exchanger plates to 46, then the universal screw coil 10 L = 8 m according to formula (1) will provide normal heating of milk by almost 10 °. The power of the heating elements 12 according to the formula (2) will also double with a constant recovery coefficient (energy saving) η = 0.86, calculated by the formula

where 80 ° is the pasteurization temperature, 4 ° is the temperature of raw milk.

If the doubled flow rate Q is passed through the previous RPT 6 with 23 plates, then the temperature difference τ and T will double to 20 °, and the power of the heating elements will need to be quadrupled to 84 kW according to equation (2). Given the given maximum power of the heating elements 12 45 kW, the maximum flow rate that can be passed through the mentioned PU will be 3000 l / h. In this case, the differences T and τ will increase to 15 °, and the recovery coefficient will decrease, respectively, to η = 0.8. Reducing the flow rate Q to 1000 l / h will lower the differential T to 5 ° and increase recovery to η = 0.93.

Thus, a screw coil 10 made of a thin-walled pipe h = 1 mm AISI316, diameter 40 mm, length L = 8 m, has optimal design parameters, allows for flow rates Q = 1000 ... 3000 l / h to warm the flow of raw milk to water temperature 80 ° С, thereby pasteurizing it with a high percentage of energy savings with a recovery coefficient in the range of 0.8 ... 0.93 compared to direct heating of milk from 4 ° С to 80 ° С in analogs [5, 6]. Compared with the twin pipe of the prototype [1] Ф20 × 2 pieces having an excess length of 15 m, which has the same constant ξ = 1.2 m at Q = 2000 l / h, washing is greatly simplified. In addition, the optimum diameter of the coil 10 (d = 40 mm) allows you to use a standard foam rubber swab F60 mm 100 mm long every three days when disassembling and cleaning the pipelines, designed to flush the F40 milk pipelines, which on farms are up to 100 linear meters long. . In this case, the wad F60 is inserted at the beginning of the screw coil 10, after which the pipeline is again assembled and the centrifugal pump 4 is turned on, with the washing solution. The centrifugal pump 4 develops a pressure P from 2.2 to 3 atm, which creates a force at a wad F = πd ² P / 4 from 25 kg to 37 kg. Due to this effort, the foam wad moves to the exit and gets stuck at the end of the helical coil. Having done this simplest procedure several times, we easily protampon the coil and mechanically clean it without a cable. Reducing the diameter of the coil in the prototype [1] by half to 20 mm reduces the force on the wad by 4 times and can lead to its jam. In addition, F20 wads are non-standard for the dairy industry and farms, which creates additional problems.

Mechanical cleaning with ruffs of a sealed cylindrical tank 14, taking into account the quick-detachable end cover 15, does not present any problems compared to the prototype coil-holder [1], but in terms of size and price, the tank-holder has several times improved performance, and also significantly simplifies and speeds up washing service.

In the nominal mode of productivity of pasteurized milk Q = 2000 l / h, the diameter of the replaceable throttle washer is 7 Ф4 mm, the temperature difference in the nozzles 17 and 8, as well as 16 and 9, corresponds to T = 10 °, the pasteurization temperature is 80 °, the recovery coefficient is η = 0 , 86, the volumes of raw milk in the refill tank 1 with a temperature of 4 ° C are replenished by level sensors 2, 3 and an external pump. In this case, whole pasteurized milk through the pipe 18 of the check valve 5, which is controlled from the temperature sensor 21 of the soaker 14, enters the outlet 19 cooled with a temperature of 4 ° + T = 14 °, which can be directly put on the packaging. However, a temperature of 40 ° C is recommended for separation on the Zh5-OSB. In this case, it is necessary to disconnect the first input of the return valve 5 from the temperature sensor 21 and connect its second input to the temperature sensor 22 "+ 40 °" of the inlet pipe 18 of the valve 5. In this case, the valve 5 will automatically discharge the pasteurized milk + 14 ° through the pipes 18 and 20 into the refill tank 1. The centrifugal pump 4 will again pass it in the circulation mode through the RPT 6, the coil 10, the holder 14, causing the milk to warm up in the refill tank 1 to 30 ° and, accordingly, the milk to be heated in the pipe 18 from 14 ° to 40 ° FROM. Only after this, the check valve 5 due to the temperature sensor 22 "+ 40 °" will block the circulation through the pipe 20 and direct the + 40 ° stream of pasteurized milk to the outlet to pipe 19. Such a regenerative heating of pasteurized milk to 40 ° C with its preparation directly for optimal separation It is technologically and energetically more profitable than reheating in VDP [5] and PCB [6] from 14 ° to 40 °.

Thus, the claimed utility model PU with a set of interchangeable throttle washers 7 D = 3 mm, 4 mm and 5 mm is a universal design, from 1000 l to 3000 l with a recovery coefficient from 0.93 to 0.8, respectively, simple and small convenient in operation, maintenance, washing and cleaning. It allows you to save from 80% to 93% of electricity compared to direct (non-regenerative) heating of analogues [5, 6]. Compared with the prototype [1, 2], it conveniently and favorably mates with further processing equipment: packers or separators. It allows you to simply rebuild the performance in accordance with the seasonal changes in the flow of milk, has a low noise level, increased productivity and a simpler design compared to rotary counterparts [4].

The proposed PU is introduced into production at the Avtomash-Vladimir enterprise (Kovrov)

Information sources

1. The device for pasteurization. Patent RU2007146478.

2. A set of equipment for pasteurization IPKS-013R-2500R. 13-01.pdf

3. Installation for pasteurization and cooling of liquid food products PMR-02-VT with an electric boiler up to 2000 l / h.

4. Installation for pasteurization and cooling of liquid food products (pasteurizer) PMR-02-VT with rotary heaters up to 1600 l / h.

5. Baths of long pasteurization. Patent RU2007139028

6. Dairy pasteurization and refrigeration unit. Patent RU 2436293 dated 05/17/2010.

Claims (2)

1. A pasteurization unit containing a raw milk refill tank with a centrifugal circulation pump and a check valve, a recuperative plate heat exchanger of counter flows of pasteurized and raw milk, a pasteurization water heating tank with a helical coil, heating elements and an associated water thermostat, as well as an extractor with a temperature sensor the refill tank through a centrifugal pump and the inlet nozzles of the heat exchanger (direct flow of raw milk) is connected by pipelines to the input of the screw screw eevika, and the output of the helical coil through the cooler and return pipes of the heat exchanger (countercurrent of pasteurized milk) is connected by pipelines to the input of the return valve, the first output of which is connected to the refill tank, and the second output is connected to the output of the unit, while the temperature sensor is connected to the electrical input of the return valve characterized in that the helical coil is made of a thin-walled pipe with a diameter of at least 40 mm and a holder in the form of a sealed cylindrical tank with a quick-detachable end cap, in addition, a second temperature sensor is also installed in the inlet pipe of the check valve, also associated with its electrical input. 2. The pasteurization installation according to claim 1, characterized in that a replaceable throttle washer is installed in the outlet of the centrifugal pump.