JP2660485B2 - Heat pump type crystal product manufacturing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crystal can containing a raw material liquid held in a vacuum and heated by heat from a condenser of a heat pump. (Including a viscous substance).

[0002]

2. Description of the Related Art For example, in a sugar refiner in which a raw material liquid containing sugar is guided into a vacuum crystallizer and heated to crystallize the sugar in the raw material liquid and take out the product (sugar), a heat pump is used. Means for utilizing heat for heating the inside of the crystal can is used.

FIG. 3 is a block diagram (system diagram) showing a main part of a sugar refining apparatus using such a heat pump. FIG.
Wherein 2 is a compressor for a refrigerant of a heat pump system,
3 is a motor for driving the compressor, 4 is a condenser, 5 is an evaporator, 6 is an expansion valve, and the refrigerant gas compressed by the compressor 2 radiates heat to the fluid to be heated in the condenser 4. It liquefies, vaporizes in the expansion valve 6 and the evaporator 5, absorbs heat, and comprises the normal heat pump returned to a compressor.

[0004] That is, the condenser 4 is connected to heating pipe lines 31 and 32 circulating through a heater 9 installed in the crystal can 1, and a refrigerant (gas) and a heating pipe are connected in the condenser 4. Road 31,
The heating fluid exchanges heat with the heating fluid flowing through the interior of the heating device 32 to generate steam. This vapor is sent to a heater 9 in the crystal can 1 where it exchanges heat with the raw material liquid in the crystal can 1 and heats it. As a result, sugar is precipitated from the raw material liquid, and vapor is taken out from the upper part of the crystal can 1 to the pipe 22.

A vacuum pump 7 is connected to an upper space in the crystal can 1 through a suction pipe 21, an evaporator 5, and a suction pipe 22, and sucks a fluid (vapor) in the crystal can 1 to produce the crystal. The inside of the can 1 is maintained under vacuum or negative pressure.

[0006] The evaporator 5 is connected to a suction pipe 22 which is open at the top of the crystal can 1. In the evaporator 5, heat is exchanged between vapor generated in the crystal can 1 and a refrigerant. Then, the heat is absorbed from the vapor, condensed, and sent to the suction pipe 21 without vapor condensed water.

[0007]

In this type of heat pump type sugar refining apparatus, the pressure in the crystal can stabilizes when the heat balance in the can is balanced, but the heat input into the can increases when the heat input into the can increases. As the internal temperature rises, the pressure rises,
Conversely, when the amount of heat output from the can increases, the pressure decreases as the temperature inside the can decreases.

Therefore, in the conventional sugar refiner using a heat pump as shown in FIG. 3, the amount of heat by the heater 9 in the crystal can 1 is the sum of the amount of heat recovered by the heat pump and the amount of heat equivalent to the shaft power of the compressor 2. Thus, there is always a relationship in which the amount of heat equivalent to the shaft power is large.

[0009] For this reason, in the conventional sugar refining apparatus,
In many cases, the heat balance in the crystal can 1 is lost, the evaporation temperature of the vapor in the crystal can in the evaporator 5 rises, and an abnormal increase in the pressure inside the can causes a decrease in the sugar function, which often occurs.

An object of the present invention is to stabilize the heat balance by accurately controlling the heat input in the crystal can to a required amount, and to maintain the pressure in the crystal can at the required pressure to produce a crystal product. Is to prevent the decline of

[0011]

SUMMARY OF THE INVENTION The present invention relates to an apparatus for producing a crystal product using a heat pump, wherein a heat balance equivalent to the shaft power of a compressor is radiated from the heat pump system to stabilize the heat balance. so,
It is characterized in that it is configured as follows.

That is, according to the present invention, while maintaining the inside of a crystal can containing a raw material liquid under a negative pressure, the inside of the can is heated by a heating fluid from a condenser constituting a heat pump cycle to crystallize from the raw material liquid. In the heat pump type crystal product manufacturing method for obtaining a crystal product in the form of a slurry or a slurry, a refrigerant supercooling means is provided in a refrigerant pipe between the condenser outlet side and the expansion valve inlet side of the heat pump cycle. The supercooling means makes the crystal can pressure almost constant while controlling the temperature of the refrigerant in accordance with the heat equivalent to the shaft power of the compressor while controlling the heat balance between the heat generated on the heat pump cycle side and the heat consumption on the crystal can side. Is maintained. In this case, it is preferable to control the amount of temperature decrease of the refrigerant subcooling means by a signal that is arithmetically controlled based on the pressure in the crystal can.

In addition, when the operating conditions fluctuate abruptly, the control temperature drop of the refrigerant subcooling means by the signal with respect to the pressure in the crystal can causes a time delay, so that the adjusting means for adjusting the negative pressure in the crystal can is adjusted. Therefore, it is preferable to control the negative pressure in the crystal can with a time constant greater than the theoretical negative pressure.

And, as a configuration for achieving the invention,
A refrigerant subcooling means is provided in a refrigerant pipe between a condenser outlet side and an expansion valve inlet side of the heat pump cycle, and a bypass which bypasses the refrigerant subcooling means is provided. By switching the flow path and the flow path of the refrigerant subcooling means or adjusting the opening thereof, and further controlling the flow rate of the refrigerant cooling fluid of the refrigerant supercooling means, the supercooling means controls the axial power of the compressor. The temperature of the refrigerant can be controlled so as to correspond to the amount of heat.

In this case, it is preferable to provide an arithmetic means for generating the control signal based on a pressure detection signal from a pressure detector for detecting the pressure in the crystal can. Further, the switching control may be configured such that a refrigerant passage switching valve is provided at a position where the bypass passage and the refrigerant subcooling unit are gathered, and switching control of the switching valve is performed based on the control signal. A refrigerant passage switching valve is provided at a position where the passage and the refrigerant subcooling unit are gathered, and an adjustment valve that adjusts an introduction flow rate of the refrigerant cooling fluid of the refrigerant subcooling unit is provided, and the switching valve is switched based on the control signal. The control valve may be configured to adjust the opening degree together with the control.

In order to cope with the time lag between the pressure inside the crystal can and the amount of temperature decrease controlled by the refrigerant subcooling means when the operating condition changes suddenly, a vacuum pump for sucking the inside of the crystal can and the crystal can are used. It is preferable to provide a vacuum adjusting valve for adjusting the passage area of the suction line to be connected, and to control the negative pressure in the crystal can with a time constant from the theoretical negative pressure by the adjusting valve.

[0017]

As described above, the pressure in the crystal can is stable when the heat in the can is balanced, and when the heat input into the can increases and the temperature in the can rises, the pressure in the can increases. Conversely, when the amount of heat output from the can increases and the temperature in the can decreases, the pressure in the can decreases.

In the heat recovery heating method using a heat pump that heats the inside of the crystal can with steam from the condenser, the amount of heat Q ₁ in the crystal can is determined by the amount of heat recovered by the heat pump.
₀ , when the heat equivalent to the compressor shaft power is Q ₄ , Equation 1 is obtained.

[0019]

## EQU1 ## Q ₁ = Q ₀ + Q ₄

That is, on the heat balance in the crystal can, the amount of heat corresponding to the power of the compressor shaft becomes an excess amount of heat. Therefore, in order to normalize the heat balance in the crystal can, it is necessary to dissipate heat (Q ₄ ) corresponding to the power of the compressor shaft in the heat pump cycle.

In the present invention, a refrigerant supercooling means for exchanging heat between the refrigerant and a cooling fluid such as cooling water or cooling air is provided in the refrigerant pipe at the outlet of the condenser of the heat pump. To release heat equivalent to the compressor shaft power from the refrigerant.

The amount of heat released from the refrigerant subcooler (that is, the heat corresponding to the power of the compressor shaft) is determined by the control signal from the control device based on the flow rate of the refrigerant flowing through the refrigerant supercooler and the flow rate of the refrigerant flowing bypassing the cooler. , Or by changing the flow rate of the cooling fluid to the refrigerant subcooler.

The amount of heat (Q ₄ ) corresponding to the compressor shaft power controlled by this controller is as follows: Q ₁₁ = heat amount of product (crystal sugar) Q ₁₂ = heat amount supplied by raw material liquid Q ₁₃ = vapor condensation from crystal can Water quantity Q ₁₄ = vent heat quantity by the vacuum pump Q ₁₅ = natural heat radiation quantity of the device When the quantity of heat exceeds ΔQ shown in equation 2, the quantity of heat is reduced by the refrigerant supercooler so as to radiate it. The flow rate of the refrigerant or the cooling fluid flowing through the cooler is controlled.

[0024]

２Q = (Q ₁₁ −Q ₁₂ ) + Q ₁₃ + Q ₁₄ + Q ₁₅

In the present invention, in particular, the pressure in the crystal can is detected and input to a control device. In the control device, a switching signal of a three-way valve (switching valve) or a refrigerant subcooler is detected based on the pressure detection signal. And outputs the opening control signal of the cooling fluid control valve provided in the cooling fluid passage to control the amount of heat released in the refrigerant subcooler.

In a still further preferred aspect of the present invention, in addition to the above-described functions, the control device adjusts the opening of the vacuum regulating valve to control the suction amount of the vacuum pump, thereby improving the responsiveness at the time of sudden changes in operating conditions. Improve.

[0027]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. It's just

FIG. 1 is a block diagram of a sugar (crystal sugar) production system according to the present invention. In FIG. 1, reference numeral 1 denotes a crystal can, which has an inlet 1a for a raw material liquid and an outlet 1b for a product (crystal sugar).

Reference numeral 2 denotes a compressor for a refrigerant of a heat pump system, 3 denotes a motor for driving the compressor, 4 denotes a condenser for heating, 5 denotes an evaporator for absorbing heat, and 6 denotes an expansion valve for expanding the refrigerant. The refrigerant gas compressed by the compressor 2 is supplied to the condenser 4
A general heat pump is formed which releases heat to the fluid to be heated to liquefy, vaporizes in the expansion valve 6 and the evaporator 5, absorbs heat, and returns to the compressor.

That is, the condenser 4 is connected with heating pipes 31 and 32 that circulate through the heater 9 installed in the crystal can 1, and a refrigerant (gas) and a heating pipe are connected in the condenser 4. Road 31,
The heating fluid exchanges heat with the heating fluid flowing through the interior of the heating device 32 to generate steam. This vapor is sent to a heater 9 in the crystal can 1 where it exchanges heat with the raw material liquid in the crystal can 1,
Heat it.

Reference numeral 7 denotes a vacuum pump, which is a vacuum regulating valve 1 described later.
2. Connected to the upper space in the crystal can 1 via the suction line 21, the evaporator 5, and the suction line 22, suck the fluid (vapor) in the crystal can 1, and evacuate the crystal can 1 Let me know.

The evaporator 5 is connected to a suction pipe 22 which is open at the top of the crystal can 1, and in the evaporator 5, heat exchange is performed between vapor generated in the crystal can 1 and a refrigerant. Heat is absorbed from the vapor, condensed into vapor condensed water, and sent to the suction line 21.

Numeral 12 is a vacuum regulating valve, which adjusts the suction amount of the vacuum pump 7 by changing the opening thereof according to a control signal from a control device to be described later. Pressure).

Reference numeral 13 denotes a pressure gauge for detecting the pressure in the crystal can 1, and reference numeral 14 denotes a pressure detector for converting the pressure detected by the pressure gauge 13 into an electric signal.

A refrigerant subcooler 20 is provided in a refrigerant line (liquid refrigerant line) 23 between the condenser 4 and the expansion valve 6, and the refrigerant subcooler 20 and the expansion valve 6 are provided. The three-way valve 15 is provided in the refrigerant pipe 24 between the two. Further, there is provided a bypass passage 16 branched from a portion of the refrigerant pipe 23 immediately upstream of the refrigerant supercooler 20 and connected to one inlet of the three-way valve 15.

The refrigerant subcooler 20 is connected to a cooling pipe 25 for guiding a cooling fluid such as cooling water, cooling air, or the like. Refrigerant (liquid) led to passage 23 and cooling line 2
The refrigerant exchanges heat with the cooling fluid guided from 5, thereby lowering the temperature of the refrigerant.

Reference numeral 17 denotes a cooling fluid regulating valve for controlling the flow rate of the cooling fluid introduced from the cooling pipe 25 into the refrigerant subcooler 20. Further, the three-way valve 15 is connected to the refrigerant subcooler 2.
The connection between the refrigerant outlet passage or the bypass passage 16 and the refrigerant pipe 24 on the inlet side of the expansion valve 6 is switched, and a commercially available three-way valve can be applied.

Reference numeral 11 denotes a control unit, which receives a detection signal of the pressure in the crystal can 1 from the pressure detector 14 and a detection signal of the refrigerant temperature at the inlet of the expansion valve 6 from the temperature detector 18.
In the control device 11, the opening degree of the cooling fluid regulating valve 17, the switching direction of the three-way valve 15, and the vacuum regulating valve 1 are determined based on the pressure in the crystal can 1 and the refrigerant temperature in the refrigerant pipe 23.
The opening degree of 2 is calculated, and an operation signal is output to these three valves 17, 15 and 12.

The operation of the heat pump type crystal product manufacturing apparatus configured as described above will be described. The refrigerant (gas) compressed by the compressor 2 (stroke A → B in FIG. 2) enters the condenser 4 via the refrigerant line 26, where the heating fluid and the heating fluid sent from the crystal can 1 via the liquid line 31 The heat is exchanged, heated, condensed and liquefied (B → C process in FIG. 2) and sent to the refrigerant pipe 23.

The heating fluid heated by the condenser 4 becomes vapor and passes through the heating pipe 31 and enters the heater 9 in the crystal can 1. The inside of the crystal can 1 is evacuated by the suction of the vacuum pump 7, and under this vacuum, heat exchange between the raw material liquid and the vapor is performed by the heater 9, and crystal sugar (product) is extracted from the raw material liquid.
Is precipitated.

On the other hand, the refrigerant in the refrigerant pipe 23 liquefied by the condenser 4 is supplied to the refrigerant subcooler 20 and the bypass path 16.
And join. When the bypass passage 16 is closed by the three-way valve 15 and the refrigerant subcooler 20 side is open, the refrigerant exchanges heat with the cooling fluid introduced from the cooling fluid line 25 in the refrigerant supercooler 20 to lower the temperature ( Cooling)
Releasing heat Q ₃ shown in (C → D process in FIG. 2). Further, after the refrigerant is sent to the expansion valve 6 and expanded, the evaporator 5 exchanges heat with vapor generated in the crystal can 1 and introduced through the suction line 22 to be absorbed and vaporized (see FIG. 2). (D → E → A stroke), and is returned to the compressor 2 through the refrigerant pipe 27.

On the other hand, the vapor (steam) that has exchanged heat with the refrigerant in the evaporator 5 is cooled down and condensed into vapor-condensed water, which is sucked into the vacuum pump 7 through the suction pipe 21 and the vacuum regulating valve 12. .

Next, the operation of the control device 11 will be described. The control device 11 includes a pressure gauge 13 and a pressure detector 14.
Pressure P and temperature detector 18 in crystal can 1 detected at
The refrigerant temperature T at the outlet of the refrigerant supercooler 20, that is, at the inlet of the expansion valve 6, detected at the step S1 is input.

In the control device 11, based on the pressure P in the crystal can 1 and the refrigerant temperature T after supercooling, a connection switching signal for the three-way valve 15, an opening signal for the cooling fluid regulating valve 17, and a vacuum regulating valve are provided. Twelve opening signals are calculated and output to these valves 15, 17 and 12.

That is, when the amount of heat input from the condenser 4 into the crystal can 1 increases, the internal pressure P increases.
In response to the detection signal of the pressure P, the three-way valve 1
5 is a refrigerant passage 2 between the outlet of the refrigerant subcooler 20 and the inlet of the expansion valve 6.
4 is connected so that the opening degree of the cooling fluid regulating valve 17 is increased to increase the amount of heat radiation in the refrigerant subcooler 20 to lower the refrigerant temperature T, thereby reducing the pressure P in the can to the set pressure. Then, the pressure in the can is maintained at this set pressure.

When the internal pressure P decreases due to an increase in the amount of heat output from the crystal can 1, the control device 11 switches the three-way valve 15 so that the bypass passage and the refrigerant passage at the inlet of the expansion valve 6 are connected. By reducing the amount of refrigerant passing through the refrigerant subcooler 20 to reduce the amount of heat radiation and increasing the refrigerant temperature T, the pressure P in the can is increased to the set pressure.

The controller 11 receives the detection signal of the refrigerant temperature T from the temperature detector 18 and switches the connection of the three-way valve 15 and adjusts the opening of the cooling fluid adjusting valve 17 so that the refrigerant temperature T reaches the set temperature. Control so that That is, crystal can 1
The internal heat balance is maintained with high accuracy by feeding back the detection signals of both the in-can pressure P and the refrigerant temperature T to the control device 11.

In the control device 11, when a sudden change occurs in the operating conditions of the device, the control device 11 receives a detection signal such as a pressure in the can, a refrigerant temperature, etc., which is input to the control device 11, and controls the vacuum control valve. By increasing the opening of the vacuum pump 12 to increase the suction capacity of the vacuum pump 7, it is possible to prevent a response delay caused by a large time constant of the entire apparatus and improve the follow-up property of the pressure P in the can.

[0049]

According to the present invention, the amount of heat corresponding to the power of the compressor shaft is radiated by the refrigerant subcooler provided in the refrigerant pipe, so that the heat balance is stabilized and the pressure rise in the crystal can is prevented. Thus, a decrease in the crystal product generation function is prevented.

According to the second and third aspects of the present invention, the amount of the refrigerant passing through the bypass passage of the refrigerant subcooler and the subcooler is adjusted by the switching valve, and the switching valve and / or the refrigerant subcooling is adjusted. The control valve for the cooling fluid to the vessel is controlled by receiving the detection signal of the pressure in the crystal can, so that the pressure in the can can be controlled with high accuracy.

According to the fourth aspect of the present invention, the opening degree of the vacuum adjusting valve provided in the vacuum pump suction path can be adjusted by the control device. In addition, it is possible to prevent a response delay due to the time constant of the device, and to control with good tracking performance even when the operating condition changes.

[Brief description of the drawings]

FIG. 1 is a system diagram of a heat pump type sugar refiner according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining the operation.

FIG. 3 is a system diagram showing a conventional heat pump type sugar refiner.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Crystal can 2 Compressor 4 Condenser 6 Expansion valve 7 Vacuum pump 11 Controller 12 Vacuum regulating valve 13 Pressure gauge 14 Pressure detector 15 Three-way valve 16 Bypass path 20 Refrigerant subcooler 21, 22 Suction line

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B01D 9/02 625 B01D 9/02 625B C13G 1/02 C13G 1/02 F25B 30/02 F25B 30 / 02 Z (56) Reference JP-A-59-132903 (JP, A) JP-A-59-80302 (JP, A) JP-A-58-121600 (JP, U) JP-A-64-39000 (JP, U) ) Hikaru 4-28100 (JP, U)

Claims (8)

(57) [Claims] 1. While maintaining the inside of a crystal can containing a raw material liquid under negative pressure, the inside of the can is heated by a heating fluid from a condenser constituting a heat pump cycle to crystallize the raw material liquid or form a slurry. A heat pump type crystal product manufacturing method for obtaining a crystal product of the above, wherein a refrigerant supercooling means is provided in a refrigerant pipe between an outlet side of a condenser and an inlet side of an expansion valve of the heat pump cycle; A method for producing a crystal product of a heat pump type, wherein the pressure of the crystal can is maintained substantially constant while maintaining the heat balance between the heat generated on the heat pump cycle side and the heat consumption on the crystal can side while controlling the temperature of the refrigerant by means. . 2. A heat pump type crystal product manufacturing method according to claim 1, wherein a temperature decrease amount of said refrigerant subcooling means is controlled by a signal which is arithmetically controlled based on said pressure in the crystal can. 3. An adjusting means for adjusting the negative pressure in the crystal can, wherein the adjusting means controls the negative pressure in the crystal can with a time constant greater than the theoretical negative pressure. Item 4. A method for producing a heat pump type crystal product according to Item 1. 4. While maintaining the inside of the crystal can containing the raw material liquid under negative pressure, the inside of the can is heated by a heating fluid from a condenser constituting a heat pump cycle to crystallize or slurry from the raw material liquid. A heat pump type crystal product manufacturing method which obtains a crystal product in the form of a crystal, comprising: a refrigerant supercooling means in a refrigerant pipe between an outlet side of a condenser and an inlet side of an expansion valve of the heat pump cycle; A bypass path is provided for bypassing the cooling means, and a predetermined control signal is used to switch the flow path between the bypass path and the refrigerant subcooling means or to adjust the opening thereof, and furthermore, to control the refrigerant cooling fluid of the refrigerant subcooling means. It is characterized by maintaining the crystal can pressure almost constant while controlling the flow rate and maintaining the heat balance between the heat generated on the heat pump cycle side and the heat consumption on the crystal can side. Heat pump crystalline product manufacturing apparatus. 5. A heat pump type crystal generating apparatus according to claim 4, further comprising arithmetic means for generating said control signal based on a pressure detection signal from a pressure detector for detecting a pressure in said crystal can. Product manufacturing equipment. 6. A heat pump according to claim 5, wherein a refrigerant passage switching valve is provided at a position where the bypass passage and the refrigerant subcooling means are gathered, and switching control of the switching valve is performed based on the control signal. Formula crystal product manufacturing equipment. 7. A refrigerant passage switching valve is provided at a position where the bypass passage and the refrigerant subcooling means are gathered, and an adjusting valve for adjusting a flow rate of refrigerant cooling fluid introduced into the refrigerant subcooling means is provided. The heat pump type crystal product manufacturing apparatus according to claim 5, wherein the opening degree of the regulating valve is adjusted together with the switching control of the switching valve based on the switching. 8. A vacuum control valve for adjusting a passage area of the crystal can is provided in a suction pipe connecting the vacuum pump for sucking the inside of the crystal can and the crystal can, and the inside of the crystal can is controlled by the control valve. 5. The heat pump type crystal product manufacturing apparatus according to claim 4, wherein the negative pressure is controlled so as to have a time constant greater than the theoretical negative pressure.