RU2337552C1 - Method of automatic process control in manufacturing puree-like concentrates - Google Patents

Abstract

FIELD: food products, mechanics.

SUBSTANCE: method of automatic process control in manufacturing puree-like concentrates implies crushing raw feedstock, boiling out the crushed mass, its forming and obtaining end product in the form of puree-like concentrate. Consumption of raw feedstock and puree-like concentrate, consumption of steam and additives introduced into the vacuum-evaporating apparatus are measured, driving power of extruder, mixer, vacuum pump, dosing pump, feeding pump, power of electric heating tubes mounted in the steam generator, quantity of moisture evaporated from the crushed mass are measured continuously. The measured parameters help specifying total heat-and-power demand for the boiling out process, defining its derivative with respect to the moisture evaporated from the crushed mass and depending on the derivative sign raw feedstock consumption is regulated in inverse relation.

EFFECT: invention allows reducing material and energy costs per end product weight unit and increasing accuracy and reliability of control over technological parameters at all stages of manufacturing puree-like concentrate.

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Description

The invention relates to the automation of technological processes and can be used to automate the production of puree concentrates.

The closest in technical essence and the achieved effect is a method of controlling the process of producing puree-canned food for baby food, including preparing raw materials, boiling, rubbing, mixing the components, homogenization, deaeration, packaging, sterilization, cooling and storage [Wild, B.F. Automation of canning production [Text] // B.F.Dikiy, A.F. Fan-Jung. - M.: Food Industry, 1966. - 342 p. S.268-270].

The disadvantage of this method of controlling the production process of puree concentrates are:

- the principles of energy conservation are not implemented, there are significant material and energy costs due to the use of continuous heat treatment;

- there is no program-logic algorithm for the functioning of the control system for the process of obtaining puree concentrates in the conditions of optimization of energy consumption per unit of evaporated moisture;

- the correction of the mode is not provided for under conditions of random disturbances at all stages of the process of obtaining puree concentrates.

An object of the invention is to reduce material and energy resources per unit mass of the finished product, increasing the accuracy and reliability of controlling process parameters at all stages of the preparation of puree concentrate.

The problem is achieved in that in a method for automatically controlling the production of puree concentrates, which includes grinding the feedstock, boiling the crushed mass, its molding and obtaining the finished product in the form of a puree concentrate, it is new that the flow rate of the raw material and puree concentrate, steam consumption are measured and additives introduced into the vacuum evaporator, continuously determine the power of the drives of the extruder, mixer, vacuum pump, metering pump, feed pump ca, the power of tubular electric heaters installed in the steam generator, the amount of moisture evaporated from the crushed mass, the total heat energy costs of the boiling process are determined by the measured parameters, their derivative is determined by the amount of moisture evaporated from the crushed mass and, depending on the sign of the derivative, affect the flow rate of the initial product in antibiotic dependence.

The circuit contains an extruder 1, a vacuum evaporator 2 with an anchor mixer 4, a vacuum pump 3, a steam generator 5, a condensate collector 6, a feed pump 7; metering pump 16; lines: feeding the feedstock into the extruder 8, feeding the crushed mass from the extruder into the vacuum evaporator 9, removing the liquid fraction (juice) 10, removing evaporated water vapor from the crushed mass into the vacuum evaporating apparatus 11, supplying steam to heat the vacuum housing an evaporator 12, condensate drainage from the twin-body housing of the vacuum evaporator to the condensate collector 13; condensate drain from the condensate collector to the steam generator 14; removal of the puree concentrate from the vacuum evaporator 15, the supply of additives (sugar syrup, flavors, structurants, stabilizers, etc.) into the vacuum evaporator 17; sensors: flow rate 18 of the feedstock, flow rate 19 of the liquid fraction (juice), flow rate 20 steam supplied to heat the body of the vacuum evaporator 2, flow rate 21 and humidity 24 of the puree concentrate, moisture content 23 of the crushed mass, flow rate 22 additives (sugar syrup, flavorings , builders, stabilizers, etc.) supplied to the vacuum evaporator, pressure 25 in the vacuum evaporator, pressure 26 steam in the steam generator, temperature 27 in the vacuum evaporator, liquid level 28 in the steam generator; the drive power of the screw in the extruder 29, the drive power of the anchor mixer in the vacuum evaporator 30, the drive power of the metering pump for feeding additives to the vacuum evaporator 31, the drive power of the vacuum pump 32, the power of the tubular electric heaters installed in the steam generator 33, the power feed pump drive 34, actuators 35-43; safety valve 45, microprocessor 44 (A, B, V, G, D, E, F, 3, I, K, L, M, N, O, P, P, C, T - input control channels, a, b , c, d, e, e, f, s, and - output control channels).

The method of automatic control of the production process of puree concentrates (figure 1) is as follows.

The feedstock (fruits: apples, apricots, peaches, pears, etc.) is fed through line 8 to the extruder 1, in which there is a gradual increase in pressure and compaction of the crushed mass of raw materials due to the reduction in the size of the screw channel of the screw of the extruder. When the screw rotates, the fruits are crushed, the resulting liquid fraction (juice) leaves through the lower perforated part of the extruder 1 and is sent for further processing along line 10.

The crushed mass leaving the extruder 1 is sent to a vacuum evaporator 2. Inside the twin-body housing of the vacuum evaporator 2, steam is supplied via line 12, and the condensate formed through line 13 is removed to the condensate collector 6.

The necessary additional components, such as additives: sugar syrup, flavorings, structure-forming agents, stabilizers, etc., are introduced into the vacuum-evaporator 2 through line 17 using a metering pump 16 At the same time, the drive of the anchor mixer 4 and the vacuum pump 3 are turned on.

Due to the depressurization and evaporation of the generated vapors from the crushed mass in the vacuum evaporation apparatus 2, the resulting puree is dried. The water vapor evaporated from the crushed mass is removed using a vacuum pump 3 via line 11, and the condensate formed in the twin-body housing of the vacuum evaporator 2 is removed via line 13 to the condensate collector 6 and then again fed back to the steam generator 5 via a closed cycle line 14 using the feed pump 7.

In the lower part of the vacuum evaporator 2, an actuator 41 is installed for removing the finished puree product.

To obtain the steam supplied to the vacuum evaporator 2, a steam generator 5 with electric heating elements and a safety valve 45 is used. According to the sensor 26, the microprocessor 44 continuously stabilizes the steam pressure in the steam generator 5 by influencing the power of the electric heating elements by means of an actuator 42. This is achieved the set capacity of the steam generator 5, the control of which is provided by the sensors of the flow rate of steam 20, steam pressure 26 and liquid level 28 generators of 5.

Information about the current value of the condensate level in the steam generator 5 is transmitted via the sensor 28 to the microprocessor 44. When the condensate level changes, the microprocessor 44 performs on-off control by the drive of the feed pump 7 using the actuator 43: it turns on the feed pump 7 when the level of condensate in the steam generator 5, measured sensor 28, the lower setpoint and turns it off when the upper setpoint is reached.

In case of emergency failures in the operation of the steam generator 5, associated with a possible increase in steam pressure in its working volume, a safety valve 45 is provided.

Information about the process of grinding the feedstock in the extruder 1, boiling the crushed mass in a vacuum evaporator 2 with continuous stirring with an anchor stirrer 4, heating the twin-body housing of the vacuum evaporator 2 with steam and obtaining a puree concentrate, preparing steam using sensors 18-34 is transmitted to microprocessor 44, which, according to the program-logic algorithm incorporated in it, provides operational control of technological parameters taking into account the bilateral restrictions imposed on them, due to GOVERNMENTAL both give the finished product high quality and economic feasibility. Secondary devices, digital-to-analog DACs and analog-to-digital ADC converters are not shown in FIG. 1.

According to the current information of the sensors 18 on the flow rate of the feedstock, the microprocessor 44 sets the drive power of the screw of the extruder 1 by acting on the actuator 36. According to the information of the sensors 18 on the flow rate of the feedstock supplied to the extruder 1 via line 8, and according to the information of the sensor 19 on the flow rate of the liquid fraction ( juice) the microprocessor 44 determines the actual value of the flow rate of the crushed mass supplied to the vacuum evaporator 2 and sets the flow rate of the additives introduced into the vacuum evaporator 2 using the actuator ISM 38. Then, from the condition of material and thermal balances, the microprocessor 44 sets the task to the necessary heat flux supplied by steam to the vacuum evaporator 2 along line 12, compares it with the set one, generates a signal of deviation of the actual value of the flow from the set one in accordance with which the pressure in the vacuum evaporator 2 by influencing the drive power of the vacuum pump 3 and the boiling temperature of the crushed fraction by influencing the steam flow using the actuator 40.

According to the current information of the sensors 18 and 19 about the flow rate of the feedstock and the liquid fraction (juice) and the sensor 23 about the current moisture content of the crushed mass supplied from the extruder 1 to the vacuum evaporator 2, the sensor 22 about the flow rate of additives 2 introduced into the vacuum evaporator, the sensor 21 on the flow rate of the obtained puree concentrate, the microprocessor 44 determines the actual value of the moisture content of the mixture of additives and the crushed mass supplied to the vacuum evaporator 2.

According to current information of the sensor 29 about the drive power of the screw of the extruder, the sensor 30 about the drive power of the anchor mixer, the sensor 32 about the drive power of the vacuum pump, the sensor 31 about the drive power of the metering pump, the sensor 34 about the drive power of the feed pump, the sensor 33 about the power of the tubular electric heaters installed in the steam generator, the microprocessor 44 continuously determines the energy consumption for the power of the drives of the extruder, mixer, vacuum pump, metering pump, feed pump, the power of tubular electric heaters, installed in the steam generator.

Then the microprocessor 44 according to the measured parameters (the total power of the extruder drives, mixer, vacuum pump, metering pump, feed pump, the power of the tubular electric heaters and the amount of moisture evaporated from the ground mass) calculates the technical and economic indicator (optimization criterion), for which the total consumption of heat and electric energy per unit of evaporated moisture was used:

where N ₁ - power consumption of the drive of the extruder, kW; N ₂ - power consumption of the drive of the anchor mixer installed in a vacuum evaporator, kW; N ₃ - power consumption of the metering pump drive for supplying additives to the vacuum evaporator, kW; N ₄ - power consumption of the vacuum pump drive, kW; N ₅ - power consumption of tubular electric heaters installed in the steam generator, kW; N ₆ - power consumption of the feed pump drive for supplying condensate to the steam generator, kW; Ц _Э - price for electricity, r / (kW · h); U is the mass fraction of moisture evaporated in the vacuum evaporator from the processed product per unit time, t / h

In accordance with the material moisture balance

- коэффициент, u_н, u_к - соответственно начальное и конечное влагосодержание увариваемой массы, кг/кг. Зависимость расхода уваренной массы (пюреобразного концентрата) от расхода исходного продукта можно представить с учетом расхода сока следующим образом:where G _A - consumption of boiled mass (puree concentrate), kg / h; G _B - the consumption of the crushed fraction, kg / h;

- coefficient, u _n , u _k - respectively, the initial and final moisture content of the boiled mass, kg / kg. The dependence of the consumption of boiled mass (puree concentrate) on the consumption of the initial product can be represented taking into account the consumption of juice as follows:

where G _IP - consumption of the starting product, kg / h; λ is the coefficient of extraction of juice from the original product.

According to the operation of the production process for producing puree concentrates, an unambiguous functional relationship has been established between the terms in the numerator of the optimization criterion (1) and the consumption of the initial product:

where a, b, c, d, e, f, g are empirical coefficients determined experimentally for each type of product.

Given the formulas (4) - (8), the technical and economic indicator (optimization criterion) (1) is reduced to

where the mass fraction of moisture U removed from the processed product per unit time, t / h, will be equal to

:Having reduced formula (9) to a form convenient for research on an extremum, we equate the first derivative of criterion (9) to zero

:

After a series of transformations, we obtain

Equation (12) is zero if its numerator is zero, i.e.

From equation (13), the extreme value of the flow rate of the initial product corresponding to the extreme consumption of heat and electric energy per unit of evaporated moisture:

.The conditions of the extremum are satisfied both at the maximum and at the minimum of the function. Therefore, it is necessary to make sure that the solution found in our case corresponds to the minimum. This can be established by the sign of the second derivative of the optimization criterion (9). Taking the second derivative of criterion (9) and equating it to zero, it is easily proved that

.

Therefore, at the point of extremum (14), there is a minimum of heat and electric energy consumption per unit of evaporated moisture.

Then, the microprocessor 44 selects the optimal operating modes of the extruder and the vacuum evaporator, taking into account the assessment of energy efficiency. For this, the microprocessor 44 according to the calculated technical and economic indicator (optimization criterion) (formula 1) determines the derivative by the amount of moisture evaporated from the crushed mass, and depending on the sign of the derivative they affect the flow rate of the initial product in the antibate dependence.

Given the steam pressure in the steam generator 5, a predetermined performance of the steam generator 5 is established by acting on the power of the electric heating elements using an actuator 42, and when the condensate level in the steam generator 5 decreases below a predetermined value, condensate is supplied from the condensate collector 6 using the feed pump 7, and when the pressure is reached steam in the steam generator of the upper limit value discharge the steam pressure through the safety valve 45.

The flow rate of steam supplied to the vacuum evaporator 2 via line 12, the current value of which is measured using the flow sensor 20, the microprocessor 44 carries out the current moisture value of the mixture of additives and the crushed fraction. Moreover, the stabilization of the moisture content of the crushed fraction in a given range of values is achieved by an operational change in the barothermal mode by acting on the drive of the vacuum pump 3 using the actuator 39 and on the steam flow in line 12 through the actuator 40.

According to the sensor 26, the microprocessor 44 continuously stabilizes the steam pressure in the steam generator 5 by affecting the power of the electric heating elements by means of an actuator 42. In this case, a predetermined performance of the steam generator 5 is achieved, which is monitored by the steam flow sensor 20 in line 12.

Information about the current value of the condensate level in the steam generator 5 is transmitted via the sensor 28 to the microprocessor 44. When the condensate level in the steam generator 5 changes, the microprocessor 44 performs two-position control of the drive of the feed pump 7 using the actuator 43: it turns on the feed pump 7 when the condensate level in the steam generator is reached 5 of the lower setpoint and turns it off when the upper setpoint is reached.

Thus, the proposed method for evaluating the effectiveness of the proposed method for the automatic control of the process of production of puree concentrates allows the selection of the optimal consumption of the initial product according to the minimum value of criterion (9), taking into account the restrictions imposed on the ranges of variation of the operational parameters of the technological process.

An example implementation of the method. As a specific example of the implementation of the method, the technology of producing puree concentrates at the Canning Factory enterprise (p. 2nd Storozhevoye, Liskinsky District, Voronezh Region) is considered.

The limits of regulation of the main technological parameters of the processes for producing puree concentrates are substantiated as a result of experimental studies: the boiling temperature of the crushed fraction in a vacuum evaporator is 68 ... 76 ° C, the vacuum in a vacuum evaporator is 0.005 ... 0.004 MPa, the nominal frequency rotating anchor stirrer under vacuum in evaporator - 0.7 ... 1.3 s ^-1, and the ground mass ratio of the additives - 1: 0.31.

As an object of research, apples of the Antonovka variety with an initial humidity of 86 ... 87% were used.

The feedstock (apples of the Antonovka variety with an initial moisture content of 86 ... 87%) is fed through line 8 to the extruder 1. The drive of the extruder 1 is turned on, with this, a gradual increase in pressure and compaction of the crushed mass of raw materials occur. When the screw rotates, the fruits are crushed, the resulting liquid fraction (juice) leaves through the lower perforated part of the extruder 1 and is sent for further processing along line 10.

The crushed mass leaving the extruder 1 is sent to a vacuum evaporator 2. Inside the twin-body housing of the vacuum evaporator 2, steam is supplied via line 12, and the condensate formed through line 13 is removed to the condensate collector 6.

The necessary additional components, such as additives: sugar syrup, flavorings, structure-forming agents, stabilizers, etc., are introduced into the vacuum-evaporator 2 through line 17 using a metering pump 16 At the same time, the drive of the anchor mixer 4 and the vacuum pump 3 are turned on.

Due to depressurization and evaporation of the generated vapors from the crushed mass in the vacuum evaporation apparatus 2, the resulting pulp is dried. The water vapor evaporated from the crushed mass is removed using a vacuum pump 3 via line 11, and the condensate formed in the twin-body housing of the vacuum evaporator 2 is removed via line 13 to the condensate collector 6 and then again fed back to the steam generator 5 via a closed cycle line 14 using the feed pump 7.

To obtain the steam supplied to the vacuum evaporator 2, a steam generator 5 with electric heating elements and a safety valve 45 is used. According to the sensor 26, the microprocessor 44 continuously stabilizes the steam pressure in the steam generator 5 by influencing the power of the electric heating elements by means of an actuator 42. This is achieved the set capacity of the steam generator 5, the control of which is provided by the sensors of the flow rate of steam 20, steam pressure 26 and liquid level 28 generators of 5.

Information about the current value of the condensate level in the steam generator 5 is transmitted via the sensor 28 to the microprocessor 44. When the condensate level changes, the microprocessor 44 performs on-off control by the drive of the feed pump 7 using the actuator 43: it turns on the feed pump 7 when the level of condensate in the steam generator 5, measured sensor 28, the lower setpoint and turns it off when the upper setpoint is reached.

In case of emergency failures in the operation of the steam generator 5, associated with a possible increase in steam pressure in its working volume, a safety valve 45 is provided.

Information on the process of grinding the feedstock in the extruder 1, boiling the crushed fraction in a vacuum evaporator 2 with continuous stirring with an anchor stirrer 4, heating the twin-body housing of the vacuum evaporator 2 with steam and obtaining a puree concentrate, preparing steam using sensors 18-34 is transmitted to microprocessor 44, which, according to the program-logic algorithm incorporated in it, provides operational control of technological parameters taking into account the bilateral restrictions imposed on them, due to ennyh both give the finished product high quality and economic feasibility.

According to the current information of the sensors 18 on the flow rate of the feedstock, the microprocessor 44 sets the drive power of the screw of the extruder 1 by acting on the actuator 36. According to the information of the sensors 18 on the flow rate of the feedstock supplied to the extruder 1 via line 8, and according to the information of the sensor 19 on the flow rate of the liquid fraction ( juice) the microprocessor 44 determines the actual value of the flow rate of the crushed fraction supplied to the vacuum evaporator 2 and sets the flow rate of additives introduced into the vacuum evaporator 2, using the Executive mech anism 38. Then, from the condition of material and thermal balances, the microprocessor 44 sets the task to the necessary heat flux supplied by steam to the vacuum evaporator 2 along line 12, compares it with the set one, generates a signal of deviation of the actual value of the flow from the set one in accordance with which the pressure in the vacuum evaporator 2 by influencing the drive power of the vacuum pump 3 and the boiling temperature of the crushed fraction by influencing the steam flow using the actuator 40.

According to the current information of the sensors 18 and 19 about the flow rate of the feedstock and the liquid fraction (juice) and the sensor 23 about the current moisture content of the crushed mass supplied from the extruder 1 to the vacuum evaporator 2, the sensor 22 about the flow rate of additives 2 introduced into the vacuum evaporator, the sensor 21 on the flow rate of the obtained puree concentrate, the microprocessor 44 determines the actual value of the moisture content of the mixture of additives and the crushed mass supplied to the vacuum evaporator 2.

According to current information of the sensor 29 about the drive power of the screw of the extruder, the sensor 30 about the drive power of the anchor mixer, the sensor 32 about the drive power of the vacuum pump, the sensor 31 about the drive power of the metering pump, the sensor 34 about the drive power of the feed pump, the sensor 33 about the power of the tubular electric heaters installed in the steam generator, the microprocessor 44 continuously determines the energy consumption for the power of the drives of the extruder, mixer, vacuum pump, metering pump, feed pump, the power of tubular electric heaters, installed in the steam generator.

Then the microprocessor 44 according to the measured parameters (the total power of the extruder drives, mixer, vacuum pump, metering pump, feed pump, the power of the tubular electric heaters and the amount of moisture evaporated from the ground mass) calculates the technical and economic indicator (optimization criterion), for which the total consumption of heat and electric energy per unit of evaporated moisture was used (see formula 1).

The productivity of the installation, depending on the initial moisture of apples that have previously undergone technological operations on washing, cleaning, sorting, is 180 ... 230 kg / h.

The microprocessor 44 selects the optimal operating modes of the extruder and the vacuum evaporator, taking into account the assessment of energy efficiency. For this, the microprocessor 44 on the calculated technical and economic indicator (formula 1) determines the specific total energy consumption (figure 2).

The optimization criterion (1) for these technological modes of obtaining puree concentrates was obtained in the form:

The optimal flow rate of the starting product G ^* is determined from the condition:

this implies

16000G ² + 120G-8000G ² -120G + 320 = 0,

G ^* = 0.2 t / h

then the value of the optimization criterion R ^* corresponding to the optimal value of G ^* is R ^* = 3320 r / t.

From the analysis of formula (15) it follows that the implementation of this method with minimum specific energy costs of 3320 r / t, with restrictions on the performance of the equipment and the quality of the puree concentrate, is achieved with a flow rate of 0.2 t / h of the starting product (Fig. 2) . A slight deviation of the consumption of the starting product from this value inevitably leads to an overspending of heat and electric energy per unit mass of the obtained puree concentrate.

As a result, the possibility of evaluating the effectiveness of the proposed method for automatic control of the production of puree concentrates by the amount of energy costs per unit mass of moisture removed is shown. The choice of the optimal consumption of the initial product for the minimum value of the specific energy costs is justified, taking into account the restrictions imposed on the ranges of variation of the operational parameters of the technological process.

Thus, the proposed method for controlling the production process of puree concentrates has the following advantages:

- ensuring minimum heat and energy costs for the production of puree concentrates;

- reduction of material and energy resources per unit mass of the finished product,

- obtaining a finished product of high quality by maintaining the most optimal duration of boiling mashed potatoes in a vacuum evaporator;

- high accuracy of maintaining technological parameters and the reliability of the automatic control system at all stages of the process of production of puree concentrate.

Claims (1)

A method for automatically controlling the process of production of puree concentrates, which includes grinding the feedstock, boiling the crushed mass, forming it and obtaining the finished product in the form of a puree concentrate, characterized in that the flow rate of the feedstock and puree concentrate, the flow rate of steam and additives introduced into the vacuum evaporator apparatus, continuously determine the power of the drives of the extruder, mixer, vacuum pump, metering pump, feed pump, the power of tubular electric heaters, installed in the steam generator, the amount of moisture evaporated from the crushed mass, the total heat energy costs of the boiling process are determined by the measured parameters, their derivative is determined by the amount of moisture evaporated from the crushed mass and, depending on the sign of the derivative, affect the flow rate of the initial product in an antibatical dependence.

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