JP2000102701A - Thin film falling type vacuum evaporator control method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable applying the same device to both cases where property of raw liquid is changed and where it is not changed. SOLUTION: Raw liquid 2 is heated and evaporated by heating steam 7 in an evaporator 5 to be separated into condensate 2a and evaporated vapor 2b. And the heating steam 7 leaving the evaporator 5 is separated into condesate 7a and uncondensed steam 7b by a drain pot 16. The evaporated steam 2b on the raw liquid side and side uncondensed steam 7b on the heating steam side are independently condensed by vacuum pumps 11a, 11b through first and second condensers 12a, 12b respectively, and steam discharge systems 14, 19 thereof are provided with evaporated steam side pressure control valve 15a and heating steam side pressure control valve 35 respectively to independently control pressure of each steam discharge system. In this way, temperatures on the heating side and evaporation side of a concentrator are independently controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for controlling a vacuum evaporating and concentrating apparatus of a thin film flow type. If you do not want to, and want to change the properties such as the addition of kogation smell, or if you want to concentrate and produce products that do not want to change the properties of the stock solution to the limit with heat-sensitive juices and the like, and products that want to change the properties with the same equipment It is valid.

[0002]

2. Description of the Related Art As a conventional thin film falling-down type vacuum evaporation concentrator, for example, there is an apparatus shown in FIG. This apparatus comprises an undiluted solution supply line 6 for supplying undiluted solution 2 in a undiluted solution tank 1 to an evaporator 5 via a preheater 4 by a undiluted solution pump 3 and a thin film falling plate 5a as a heat transfer element. The evaporator 5 is heated by the heating steam 7 to evaporate and concentrate, the separator 8 separates the liquid 2a concentrated by the evaporator 5 and the evaporation steam 2b, and the concentrated liquid 2a separated by the separator 8 is concentrated liquid. Concentrated liquid take-out system 10 taken out by take-out pump 9 and evaporated vapor 2b separated by separator 8
Is discharged by a water ring type vacuum pump 11, passes through a condenser 12 on the way, is cooled by cooling water 13 in the condenser 12, condenses the vapor 2b, and discharges the vapor 2b. Pressure control, which is installed on the condensate outlet side of the vessel 12 and compares the value set in the controller 15a with the pressure (vacuum pressure) on the condensate outlet side to control the pressure of the evaporative vapor discharge system 14 to a predetermined pressure. Control valve 1
5, a drain pot 16 for separating a condensed liquid 7a of the heated steam 7 condensed by the evaporator 5 and an uncondensed vapor 7b, and a condensate 7a separated by the drain pot 16 to a drain pump 17
The condensed liquid discharge line 18 and the uncondensed vapor 7b separated by the drain pot 16 are discharged by a vacuum pump 11 and pass through a condenser 12 on the way, cooled by cooling water 13 in the condenser 12 and An uncondensed vapor discharge line 19 for condensing and discharging the uncondensed vapor 7b is mainly configured, and the evaporator 5 and the preheater 4 are supplied with the heated steam 7 from the heated steam supply lines 20 and 21.

In FIG. 3, reference numeral 22 denotes a control valve for controlling the flow rate installed in the heating steam supply line 20, and the value set in the controller 22a and the flow control valve
Is controlled so that the flow rate of the heating steam 7 supplied to the evaporator 5 becomes a predetermined value.
23 and 24 are a temperature alarm and a pressure alarm installed in the heating steam supply line 20. Reference numeral 25 denotes a separator liquid level control valve installed in the undiluted liquid supply line 6,
The value set in 5a is compared with the liquid level in the separator 8, and the liquid level in the separator 8 is controlled to be constant. Reference numeral 26 denotes a supply amount control valve installed in the heating steam supply line 21 to the preheater 4, which compares the value set in the controller 26a with the detected temperature of the stock solution after passing through the preheater 4, and determines the preheating temperature of the stock solution. Is controlled to be a predetermined temperature. 27 is a concentrated liquid take-out amount control valve installed in the concentrated liquid take-out line 10,
The value set in the controller 27a is compared with the concentration of the concentrated liquid exiting the separator 8, and if the concentration is not the predetermined concentration, the concentration is returned from the return line 28 to the stock solution supply line 6 of the evaporator 5, and the predetermined concentration is returned. It is controlled to take out when it becomes. The line 29 is a condensate discharge line connected to the condensate outlet side of the condenser 12, and is provided with a condensate discharge pump 30. When only the line 36 is used, the operation can be performed with the evaporation heating temperature kept constant without changing. A line 31 is a purified water supply line to the stock solution tank 1, and a line 32 is a purified water supply line to the washing nozzle 33 in the separator 8, both of which are used during the washing operation performed after the concentration operation is completed. is there.

[0004] The conventional apparatus shown in FIG. 3 evaporates and concentrates the undiluted solution 2 supplied to the evaporator 5 with the heated steam 7. In step 5, the stock solution 2 is evaporated and concentrated under vacuum. At this time, the operation of changing only the evaporation temperature of the stock solution 2 in the evaporator 5 can be easily performed by changing the set value of the controller 15a.

[0005]

In the case of concentrating a food liquid, an appropriate temperature operating condition corresponding to the product quality is required. For this reason, when concentrating various kinds of liquids,
A plurality of operating conditions according to the type are required. For that purpose, it is necessary to change the heat transfer area of the heat transfer plate of the evaporator 5, but this cannot be easily coped with. Therefore, in the conventional apparatus, the same apparatus cannot be applied both when the property of the stock solution is changed and when it is not changed, and a plurality of concentrating apparatuses corresponding to the product quality are required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method and an apparatus for controlling a thin film falling-down type vacuum evaporation concentrator which can apply the same apparatus both when the properties of a stock solution are changed and when the properties are not changed.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention relates to a concentrator incorporating a thin-film falling plate as a heat transfer element. By separating the evaporator vapor discharge system on the stock solution side and the pressure of each vapor discharge system independently, the heating side temperature and the evaporator side temperature of the evaporator can be controlled independently. Control method of thin-film falling-type vacuum evaporating and concentrating apparatus, and undiluted solution supply line for supplying undiluted solution to evaporator by undiluted solution pump, thin-film falling type plate as heat transfer element, and undiluted solution heated by heating steam under vacuum An evaporator for evaporating and concentrating the liquid, a separator for separating the liquid concentrated by the evaporator from the vapor, a concentrated liquid take-out system for taking out the concentrated liquid separated by the separator by a concentrated liquid take-out pump, and a separator. The evaporative vapor separated by the heater is discharged by a first vacuum pump, passes through a first condenser, and is cooled by cooling water in the first condenser to condense and discharge the evaporative vapor. A vapor discharge system, which is installed on the condensate outlet side of the first condenser, controls a pressure of the evaporative vapor discharge system to a predetermined pressure by comparing a value set in a controller with a pressure on the condensate outlet side. A control valve for controlling the pressure of the evaporative vapor side, a drain pot for separating the condensate of the heated vapor condensed in the evaporator and an uncondensed vapor, and a condensate discharge system for discharging the condensate separated in the drain pot by a drain pump And the uncondensed vapor separated by the drain pot is discharged by a second vacuum pump, passes through a second condenser on the way, and is cooled by cooling water in the second condenser to condense the uncondensed vapor. Not condensed And a gas discharge system, the second
For controlling the pressure of the uncondensed vapor discharge system to a predetermined pressure by comparing the value set in the controller with the pressure at the condensate exit side, which is installed on the condensate exit side of the condenser A control valve for controlling the pressure of each steam discharge system independently through the control valve for controlling the pressure of the evaporative steam and the control valve for controlling the pressure of the heated steam, thereby controlling the temperature of the evaporator on the heating side. And a controller for a thin film falling-down type vacuum evaporation concentrator characterized by independently controlling the temperature and the evaporation side temperature.

Since the present invention has the above-described structure, the evaporation temperature on the undiluted solution side, the heating temperature on the heated steam side, and the temperature difference of the evaporator using the thin-film falling plate as the heat transfer element can be freely changed. Accordingly, when one concentrator is used to produce multiple types of products with a single stock solution, or a multi-concentration operation in accordance with the product quality required for a multi-stock solution, it is possible to diversify the concentrated products.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flow sheet showing a control system for a single-effect concentrator according to an embodiment of the present invention, which is different from the conventional flow sheet shown in FIG.
4 is the added configuration, and the other configurations are the same. Therefore, they are denoted by the same reference numerals as those in FIG. 3 and the description of the overlapping portions is omitted.

According to the present invention, the uncondensed vapor discharge system 19 on the heated vapor side exiting the evaporator 5 and the evaporative vapor discharge system 14 on the stock solution side are separated, and the pressures of the respective vapor discharge systems 19 and 14 are independently controlled. Thus, the heating side temperature and the evaporation side temperature of the evaporator 5 are controlled independently. For this purpose, as shown in FIG. 1, the evaporative vapor discharge system 14 on the undiluted solution side, which has exited the separator 8, is connected to the first condenser 12a and the first vacuum pump 11a of a water ring type by a line 36, and is connected to a drain pot. 16
The uncondensed steam discharge system 19 on the heated steam side which has exited the line 3 is connected to the second condenser 12b and the second vacuum pump 11b of a water ring type by line 3.
Connect with 7. Further, a heating device for controlling the pressure of the uncondensed vapor discharge system 19 to a predetermined pressure by comparing the value set in the controller 35a with the pressure at the condensate outlet side, at the condensate outlet side of the second condenser 12b. The control valve 35 for steam side pressure control is installed.

The reason why the present invention is configured as described above will be described with reference to FIG. FIG. 2 is a diagram for explaining the behavior of the undiluted solution evaporation side and the heated steam side on both sides of the heat transfer plate 5a in the evaporator 5 using the thin film falling type plate. Is also flowing from top to bottom,
The condition of the heat transfer plate 5a at the free temperature difference is represented by the following equation: Q = U · A · ΔT Q: Exchange heat (evaporation) ... U: U value (overall heat transfer coefficient) A: Heat transfer area: ΔT: Temperature difference: Constant of evaporation capacity (constant heat exchange Q: constant), U value: constant (When the evaporation side temperature is constant on a thin film falling plate)
If the temperature difference ΔT is changed (the heating temperature is changed), for example, if ΔT = 2ΔT, Q = U · A / 2 · 2 △ T
= U · A · ΔT, and to realize A / 2, in the thin film falling-down plate, the heat exchange ends on the way, and the heat transfer surface on the downstream side does not contribute to the heat transfer. As described above, the stock solution 2 is flowed from top to bottom, and the heating steam 7 is in a proportional relationship between the gas pressure and the temperature in the thin film flow-down plate flowing from top to bottom.

Accordingly, the present invention utilizes the above phenomenon to
The pressure of the uncondensed vapor discharge system 19 on the heated steam side and the pressure of the evaporated vapor discharge system 14 on the raw liquid side that has exited the evaporator 5 are controlled by a control valve 35 for controlling the pressure on the heated steam side and a control valve 15b for controlling the pressure on the evaporated steam side. , The heating-side temperature and the evaporation-side temperature of the concentrator are controlled independently.

Thus, the same concentrating apparatus can be applied both when the properties of the stock solution are changed and when they are not changed.

[0014]

According to the present invention, the evaporation temperature on the stock solution side, the heating temperature on the heated steam side, and the temperature difference can be freely changed in a concentrator using a thin film flow-down plate as a heat transfer element. Therefore, when a single concentrator is used to produce multiple types of products with a single stock solution, or a multi-concentration operation that matches the product quality required for a multi-stock solution, it becomes possible.
A variety of concentrated products can be provided.

[Brief description of the drawings]

FIG. 1 is a flow sheet showing a control system of a single-effect concentrator according to an embodiment of the present invention.

FIG. 2 is an explanatory view of the behavior of the undiluted liquid evaporation side and the heated steam side on both sides of a heat transfer plate in an evaporator using a thin film falling type plate.

FIG. 3 is a flow sheet showing a control system of a conventional single-effect concentrator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Undiluted solution tank 2 Undiluted solution 2a Concentrate 2b Evaporated vapor 3 Undiluted solution supply pump 4 Preheater 5 Evaporator 5a Thin film falling type plate (heat transfer plate) 6 Undiluted solution supply line 7 Heated vapor 7a Condensate 7b Uncondensed vapor 8 Separator 9 Concentrate Removal pump 10 Concentrate removal line 11 Vacuum pump 11a First vacuum pump 11b Second vacuum pump 12 Condenser 12a First condenser 12b Second condenser 13 Cooling water 14 Evaporation vapor discharge system 15 Pressure control Valve 15a Controller 15b Control valve for evaporative vapor side pressure control 16 Drain pot 17 Drain pump 18 Condensate discharge system 19 Uncondensed vapor discharge system 20, 21 Heated steam supply line 22 Flow control valve 22a Controller 23 Temperature alarm 24 Pressure Alarm 25 Separator liquid Control valve 25a Controller 26 Supply amount control valve 26a Controller 27 Concentrate removal amount control valve 27a Controller 28 Return line 29 Condensate discharge line 30 Condensate discharge pump 31 Purified water supply line 32 Purified water supply line 33 Cleaning nozzle 34 Additional configuration according to the present invention Part 35 Control valve for heating steam side pressure control 35a Controller 36 First uncondensed gas discharge line 37 Second uncondensed gas discharge line

Claims (2)

[Claims] 1. A concentrating device incorporating a thin film falling plate as a heat transfer element, wherein a discharge system for uncondensed vapor on a heated vapor side exiting an evaporator and a discharge system for evaporated vapor on a stock solution side are separated. A method for controlling a thin film falling vacuum evaporation concentrator, wherein the heating side temperature and the evaporation side temperature of an evaporator are independently controlled by independently controlling the pressures of respective steam discharge systems. 2. An undiluted solution supply line for supplying undiluted solution to an evaporator by an undiluted solution pump; an evaporator for evaporating and concentrating the undiluted solution by heating the undiluted solution with heating steam under vacuum; A separator for separating the concentrated liquid separated by the separator from the evaporated vapor, a concentrated liquid removal system for removing the concentrated liquid separated by the separator by the concentrated liquid removal pump, and discharging the evaporated vapor separated by the separator by the first vacuum pump And an evaporative vapor discharge system that passes through a first condenser on the way, condenses and discharges the evaporative vapor by cooling with the cooling water in the first condenser, and a condensate outlet side of the first condenser. A control valve for controlling the pressure of the evaporative vapor discharge system at a predetermined pressure by comparing the value set in the controller with the pressure at the outlet of the condensate; A drain pot that separates the condensate of the heated vapor condensed by the generator from uncondensed vapor, a condensate discharge system that discharges the condensate separated by the drain pot by a drain pump, and an uncondensed liquid separated by the drain pot The steam is discharged by a second vacuum pump and passes through a second condenser on the way, and the second
An uncondensed vapor discharge system that is cooled by cooling water in a condenser to condense and discharge the uncondensed vapor, a condenser set at a condensed liquid outlet side of the second condenser, and a value set in a controller and the condensate. A control valve for controlling the pressure of the uncondensed steam discharge line to a predetermined pressure by comparing the pressure with the pressure on the liquid outlet side, and a control valve for controlling the pressure of the evaporated steam and a pressure control for heating the steam. Characterized in that the heating-side temperature and the evaporation-side temperature of the evaporator are independently controlled by independently controlling the pressure of each steam discharge system via a control valve for thin film flow. Concentrator control device.