JPH0111040Y2 - - Google Patents

Description

[Detailed description of the invention] <Industrial field of application> The present invention is a control device that adjusts the pressure inside each vacuum crystallizer without mutual interference in a plant in which multiple vacuum crystallizers used for sugar refining are operated in parallel. Regarding.

<Prior art> The prior art will be explained based on FIGS. 3 to 5. FIG. 3 is a basic configuration diagram of a vacuum crystal can.

For example, as shown in FIG. 3, the sugar solution 3 to be roasted is poured into an upright crystallizer 1 having a calandria-type heating section 2 from the bottom via a control valve 4. Supplied. Heating steam 5
is applied to the heating section 2 in the crystal can 1 via the control valve 6. The sugar solution is concentrated by heating and evaporated, and at the same time, the sugar solution is replenished, and when a crystallization concentration that allows crystal precipitation is reached, seed sugar is added to the sugar solution from the feeder 7 through the valve 8. to generate crystal nuclei suitable for each variety. After that, in order to prevent these crystal nuclei from combining with each other and from generating new crystal nuclei of undesired species (pseudocrystals), add water or sugar solution while monitoring the inside of the can. , continue concentration and crystal growth. When the crystals grow to a certain extent, the volume of the crystals per unit volume in the white (mixture of sugar solution and crystals) exceeds a certain value, and the crystals come quite close to each other, it becomes false. It becomes relatively difficult for crystals to form, and it is further concentrated, making it easier for crystals to grow, and by supplying sugar solution, the volume in the can increases to a certain value, and the grain size of the crystals grows to the required size. ,
The white matter 9 inside the can is discharged from the discharge valve 10. The discharged white flour is separated into crystals and sugar solution using a centrifuge, and the sugar solution is repeatedly used to make decoction sugar. In order to adjust the concentration of white flour in the roasted sugar to an appropriate value, a difference water 11 can be supplied into the can 1 through a control valve 12. Reference numeral 13 is a hardness meter that detects the fluid under the white, and reference numeral 14 is a program controller that controls opening and closing of the sugar solution valve 4 and the differential water valve 12 based on this detection signal. The steam in the can 1 is drawn to a condenser 15 by a vacuum pump 16, and the condenser 1
5 is cooled by water 17.

18 is a pressure sensor that detects the pressure inside the can, and its output PV is led to a pressure regulator 19 as a measured value. SV is the pressure set value, MV is the adjustment output, and the opening degree of the air 22 bleed valve 21 provided in the middle of the pipe line 20 connected to the vacuum pump is controlled so that the measured value PV matches the set value SV. controlled by.

In a plant where a plurality of vacuum crystal cans with such a configuration are installed, a vacuum pump 16 is installed for each vacuum crystal can.
Since it is uneconomical to provide a vacuum pump and takes up a lot of space, it is common practice to provide a single vacuum pump, or to use a vacuum pump used in other equipment if there is surplus capacity.

FIG. 4 shows a conventional configuration using a common vacuum pump 16. 1 ₁ to 1 _o are n vacuum crystal cans, and elements corresponding to those in FIG. 3 are indicated by the same reference numerals with a suffix symbol corresponding to each can. 23 is a main pipe connected to the vacuum pump 16, 24 ₁ ...2
4 _o is a branch pipe connecting this main pipe to the capacitors 15 ₁ . . . 15 _o of each vacuum crystal can.

FIG. 5 shows another example of the conventional configuration, in which a regulating valve 25 1 is used as a means for regulating the pressure inside the can, regulating the amount of cooling water 17 ₁ ... _{17 o} to the condenser 15 ₁ ... 15 _o.
...25 _o is provided, and the output MV ₁ of the controller 19 ₁ ...19 _o
...This is an example of a configuration in which the amount of cooling water is controlled by MV _o , and the basic configuration is the same as that in Fig. 4.

In such a conventional configuration, the branch pipes of each vacuum crystal can are directly connected via the main pipe, so if the pressure adjustment value in each can is different or the pressure in the can fluctuates due to disturbance. This has the disadvantage that it is difficult to achieve highly accurate and stable internal pressure control for each vacuum crystallization can, as the effects of this type of vacuum crystallization can easily affect the pressure in other cans.

<Purpose> The present invention solves the above problems that occur when a common vacuum pump is used, and realizes a control device that enables highly accurate and stable pressure control of each vacuum crystal can without mutual interference with others. The purpose is to

<Configuration of the invention> The structural features of the invention include a plurality of vacuum crystal cans, a vacuum pump commonly provided to these vacuum crystal cans, and a main pipe connected to the vacuum pumps with the above-mentioned components. A plurality of branch pipes connecting the vacuum crystal cans, a plurality of throttle valves provided in each branch pipe, and a plurality of bleed valves provided in each branch pipe between the throttle valve and the vacuum crystal can, It has a plurality of pressure regulators and a plurality of pressure sensors provided corresponding to each of the vacuum crystal cans, and each of the regulators uses the PV value from the pressure sensor and the SV set for each vacuum crystal can. The opening degree of the throttle valve and bleed valve of each branch pipe is controlled in the opposite direction based on the value, with a border around 50% of the output.

<Embodiment> The present invention will be described below with reference to the embodiment shown in FIG. 1 and the operational diagram shown in FIG. Figure 4,
Elements that are the same as those in the conventional configuration shown in FIG. 5 are given the same reference numerals and explanations will be omitted.

The feature of the present invention is that a throttle valve 25 1 ... _{25 o} is provided in each branch pipe 24 ₁ ... 24 o on the way to the condenser _{15 1} ... 15 _o , and the output of the controller MV ₁ ... MV _o
Set the pressure inside each vacuum crystal can by adjusting the opening degrees of these throttle valves and bleed valves 21 ₁ ... 21 _o to set the pressure SV ₁
...It is controlled by SV _o .

FIG. 2 shows the valve opening characteristics of the bleed valve 21 _i and the throttle valve _{25 i corresponding} to 0 to 100% of the controller output MV _i in the i-th vacuum crystal can 1 i. Therefore, the bleed valve 21 _i has a valve opening characteristic of 100% → 0% in response to MV _i from 0 → 50%,
Throttle valve 25 _i is 0% → 50% → 100% of MV _i
Has 100% valve opening characteristics. Due to such a split characteristic of the valve opening degree, the pressure inside the vacuum crystal can is adjusted by selecting one of the bleed valve or the throttle valve according to the output of the controller.

The present invention has a configuration in which throttle valves 25 ₁ ... 25 _o are provided in the middle of the branch pipes 24 ₁ ... 24 _o , and the function of this throttle valve is to isolate the connection with other vacuum crystal cans via the main pipe 23. mutual interference is prevented.
That is, in general, the vacuum capacity of the vacuum pump 16 is larger than the amount of bleed by the bleed valve, so in normal use, the opening of the throttle valve is controlled to an extremely small opening, and the pressure on the input and output sides of the throttle valve is controlled to a very small degree. The difference is large, and this large pressure difference effectively achieves isolation from other vacuum crystal cans.

<Effects> As explained above, according to the present invention, multiple vacuum crystal cans can be operated in parallel by adjusting each pressure to a different level using one commonly provided vacuum pump, and each can be operated in parallel. It is possible to completely eliminate mutual interference caused by pressure fluctuations in the crystal can and realize a highly accurate and stable pressure control device.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram showing one embodiment of the present invention;
The figure is an explanatory diagram of its operation, FIG. 3 is a basic configuration diagram of a vacuum crystal can, and FIGS. 4 and 5 are configuration diagrams showing an example of a conventional control device. 1 ₁ ~ 1 _o ... Vacuum crystal can, 15 ₁ ~ 15 _o ... Capacitor, 16 ... Vacuum pump, 17 ₁ ~ 17 _o ...
…Cooling water, 18 ₁ to 18 _o …Pressure sensor, 19 ₁
~19 _o ...Controller, 21 ₁ ~21 _o ...Bleed valve, 23...Main pipe, ₂₄₁ ~24 _o ...Branch pipe,
25 ₁ ~ 25 _o ... Throttle valve.

Claims (1)

[Scope of utility model registration request] A plurality of vacuum crystal cans, a vacuum pump commonly provided to these vacuum crystal cans, a plurality of branch pipes connecting each of the vacuum crystal cans to the main pipe connected to the vacuum pump, and each A plurality of throttle valves provided in the branch pipes, a plurality of bleed valves provided in each branch pipe between the throttle valves and the vacuum crystal cans, and a plurality of pressure valves provided corresponding to each of the vacuum crystal cans. It has a controller and a plurality of pressure sensors, each of the controllers is provided in each of the branch pipes based on the PV value from each of the pressure sensors and the SV value set for each vacuum crystal can, And the output of the pressure regulator above is 50%.
A vacuum crystal can pressure control device characterized in that the opening degrees of a throttle valve and a bleed valve, whose valve opening degrees are approximately 0% in the vicinity, are controlled in mutually opposite directions with a border around 50% of their output.