JP5514480B2 - Drying system comprising a heat pump unit and a temperature raising device - Google Patents

Description

  The present invention relates to a continuous hot air drying apparatus such as a fluidized bed dryer or a rotating drum dryer, and in particular, a dryer that requires a high-temperature drying gas can be operated efficiently as an entire drying system. The present invention relates to a drying system including a heat pump unit and a temperature raising device.

In recent years, environmental conservation efforts have become active, and from the viewpoint of so-called energy saving, it has been attempted to apply a heat pump unit as a heat source in a drying apparatus.
Specifically, an apparatus in which a heat pump unit using a chlorofluorocarbon refrigerant is applied to a so-called band dryer has been developed (see, for example, Patent Document 1).

By the way, the band dryer is provided with a plurality of stages of net conveyors in which drying is performed in contact with a dry gas when an object to be processed moves on a track such as a net conveyor disposed in a drying chamber. Thus, processing for a long time can be performed.
On the other hand, in a continuous hot air drying apparatus such as a fluidized bed dryer or a rotary drum dryer that performs processing in a relatively short time, it is not realistic to apply a heat pump unit to the heat source.

  Specifically, in fluidized bed dryers, etc., the residence time (processing time) of the object to be processed in the dryer is short, and a high temperature dry gas is required at the initial stage of drying. In the heat pump using the above refrigerant, the temperature of the hot air obtained is about 50 ° C., and the temperature necessary for drying in a short time cannot be obtained. Therefore, it is impossible to operate efficiently, which leads to an increase in cost.

Japanese Patent No. 3957665

  The present invention has been made in view of such a background, and makes it possible to apply a heat pump unit as a device for supplying a high-temperature dry gas to a continuous hot-air drying apparatus, and to perform drying. The technical issue is the development of a drying system that includes a new heat pump unit and a temperature raising device that has high energy efficiency as a whole system and that can perform stable operation with high energy efficiency.

That is, the drying system comprising the heat pump unit and the temperature raising device according to claim 1 is a drying system comprising a dryer and an air supply mechanism for supplying a drying gas to the dryer. A continuous hot air dryer, and the air supply mechanism includes a heat pump unit, and the air supply mechanism further includes a heating gas for raising the temperature of the dry gas heated by the heat pump unit. And a heat recovery mechanism for recovering the heat remaining in the heat medium used in the temperature raising device in the working water as a heat source supplied to the evaporator in the heat pump unit . It is characterized by this.

Furthermore, the drying system comprising the heat pump unit and the temperature raising device according to claim 2 is provided with a configuration for raising the temperature of the working water by the warm waste water discharged from the peripheral equipment in addition to the above requirements. It is characterized by this.

Furthermore, in the drying system comprising the heat pump unit and the temperature raising device according to claim 3 , in addition to the above requirements, the working water supplied to the evaporator in the heat pump unit is adjusted to the optimum operating temperature range of the heat pump unit. It is characterized by being.

Furthermore, the drying system comprising the heat pump unit and the temperature raising device according to claim 4 is characterized by comprising a plurality of the heat pump units in addition to the above requirements.

In addition to the above requirements, the drying system including the heat pump unit and the temperature raising device according to claim 5 is characterized in that the heat pump unit uses carbon dioxide as a refrigerant.
The above problems can be solved by using the configuration of the invention described in each of the claims as a means.

First, according to the first aspect of the invention, the temperature of the dry gas heated by the heat pump unit can be set to about 90 ° C., and the dry gas is required for the continuous hot air dryer by the temperature rising device. The temperature can be raised to a temperature. For this reason, it becomes possible to constitute a drying system to which a continuous dryer such as a fluidized bed dryer that is a dryer that requires a high-temperature dry gas is applied, and an operation with high energy efficiency can be performed.
In addition, by supplying surplus heat remaining in the heat medium used in the temperature raising device to the working water after the heat is released in the heat pump unit, the energy efficiency of the entire drying system is further improved and reduced. Driving at running cost is possible.
That is, by increasing the temperature of the working water, the amount of working water supplied to the heat pump unit can be reduced. As a result, the energy efficiency of the entire drying system is improved, and operation at a low running cost is possible. .

Furthermore, according to the invention described in claim 2 , by effectively using surplus heat such as warm waste water discharged from the peripheral equipment of the drying system, the energy efficiency of the entire drying system is improved, thereby further reducing the running cost. Can be operated.

Furthermore, according to the invention described in claim 3 , the heat pump unit can be operated efficiently, and the operation at a low running cost is promoted.

Furthermore, according to the invention described in claim 4 , since the variation of the supply form of the dry gas is increased, the temperature and the air volume of the dry gas are optimized according to the type, properties, throughput and configuration of the dryer. And good drying can be performed.

Furthermore, according to the invention described in claim 5 , by using carbon dioxide as a refrigerant, the temperature of the dry gas heated by the heat pump unit can be increased. Further, by further raising the temperature of the dry gas with a temperature raising device, the continuous hot air drying device can be operated to realize high energy efficiency.

It is a block diagram which shows the Example which comprised the drying system of this invention so that two heat pump units might be provided. It is a skeleton figure showing a temperature raising device. It is a block diagram which shows the Example which comprised the drying system of this invention so that one heat pump unit might be provided.

  The form of the drying system provided with the heat pump unit and the temperature raising device of the present invention is as shown in the following examples, but appropriate modifications are made to this example within the scope of the technical idea of the present invention. Is also possible.

A drying system S (hereinafter referred to as a drying system S) including a heat pump unit and a temperature raising device according to the present invention includes a dryer 1 and an air supply mechanism for supplying a drying gas D to the dryer 1. It is made up of. Specifically, as shown in FIG. 1, as an example, a dryer 1, a heat pump unit 2 and a temperature raising device 5 constituting an air supply mechanism are provided as main elements, and a heat source is provided for the heat pump unit 2. A working water tank 4 for supplying working water M is connected.
In the drying system S of the present invention, a continuous hot air dryer is applied as the dryer 1, the residence time (processing time) of the workpiece H in the dryer 1 is short, and further, the initial drying stage is performed. The drying process by the continuous dryer 1 that requires the high-temperature drying gas D at the stage can be performed in a more stable state with high energy efficiency while using the heat pump unit 2. .
Hereinafter, the components of the drying system S will be described in detail, and then the operation mode of the drying system S will be described.

First, the dryer 1 is a fluidized bed dryer which is an example of a continuous hot air dryer. The dryer 1 uses the inside of the housing 10 as a processing space for drying. The drying gas D is supplied from below the ventilation plate 11 provided so as to divide the processing space vertically, and the ventilation plate 11 is dried while forming a fluidized bed on the workpiece H located on the substrate 11.
For this reason, an air inlet 12 is formed at the lower part of the casing 10, an inlet 13 is formed at the upper front (left side in FIG. 1), and an exhaust outlet at the upper rear (right side in FIG. 1). 14 is formed, and a discharge port 15 is formed with respect to the duct 10a connected further to the rear and above the vent plate 11.
Moreover, the blower fan 16, the cyclone 17, and the exhaust fan 18 are provided as peripheral equipment of the dryer 1, and these connection states are demonstrated in detail later.

In this embodiment, a configuration is adopted in which a dam plate 11a is provided in the middle of the ventilation plate 11, and the workpiece H that has been dried to some extent passes over the dam plate 11a and moves to the next drying stage. For this reason, the lower space of the ventilation plate 11 is also divided below the barrier plate 11a, and the air supply ports 12A and 12B are formed in the respective spaces. Further, although not shown in the figure, the workpiece H may be moved by releasing the barrier plate 11a upward at an appropriate time interval.
Further, in this embodiment, a fluidized bed dryer is adopted as the dryer 1, but other continuous hot air dryers such as a fluidized bed granulator dryer, a band dryer or an air dryer can also be adopted.

Next, the heat pump unit 2 will be described. The heat pump unit 2 includes a condenser 21, an expansion valve 22, an evaporator 23, and a compressor 24 to form a heat pump cycle. As an example, carbon dioxide is used. A refrigerant is used. In addition, the temperature of the dry gas D heated by the heat pump unit 2 can be increased by employing carbon dioxide as the refrigerant. Incidentally, at present, the heat pump unit 2 using carbon dioxide as a refrigerant has been put into practical use as being capable of increasing the temperature of the dry gas D, but in the future, a heat pump unit having equivalent performance using other refrigerants will be used. When 2 is put into practical use, this can also be adopted.
Further, in this embodiment, as will be described in detail later, as shown in FIG. 1, a plurality of heat pump units 2 are provided. Shall.

  Further, as shown in FIG. 1 and FIG. 2A, the temperature raising device 5 includes, as an example, a plate fin type heat exchanger 51 as a main member. A pipe 52 provided with a plurality of radiating fins 53 on the side periphery is disposed. And between the fluid (steam, etc.) passing through the pipe 52 and the fluid (dry gas D1) in contact with the radiating fins 53 in the process of entering the heat exchanger 51 from the inlet 54 and exiting from the outlet 55 to the outside. Heat exchange will be performed.

And as shown in FIG. 1, the drying system S is comprised combining the said dryer 1, the heat pump unit 2 (2A, 2B), the working water tank 4, and the temperature raising apparatus 5. As shown in FIG.
That is, in this embodiment, a configuration is adopted in which dry gases D1 and D2 having different temperatures with respect to the dryer 1 are supplied to the air supply ports 12A and 12B, respectively.
And the blower fans 16A and 16B are connected to the input side of the condenser 21 in the heat pump units 2A and 2B by the pipe P, and between the output side of the condenser 21 and the air inlets 12A and 12B of the dryer 1. Connected by a pipe P.
In addition, the input side and the output side of the evaporator 23 in the heat pump units 2 </ b> A and 2 </ b> B are connected to the working water tank 4 by the pipe P, and the pump 41 is interposed between the input side of the evaporator 23 and the working water tank 4. Is provided.
The working water tank 4 is provided with a temperature sensor T1 for measuring the temperature of the working water M accommodated therein.

The pipe 52 is supplied with steam from an appropriate steam generator (not shown), and is provided with a regulating valve 56 for regulating the amount of steam.
The pipe P between the heat exchanger 51 and the air inlet 12A in the dryer 1 is provided with a temperature sensor T2 for measuring the temperature of the dry gas D1, and the detected value of the temperature sensor T2 Based on this, the opening degree of the control valve 56 is adjusted by an appropriate control device.
Further, the pipe line P between the heat pump unit 2A and the heat exchanger 51 is provided with a temperature sensor T4 for measuring the temperature of the dry gas D1, and an appropriate value is determined based on the detected value of the temperature sensor T4. The operation state of the compressor 24 is adjusted by the control device, and is automatically controlled so that the temperature of the dry gas D1 detected by the temperature sensor T4 becomes a predetermined value (for example, 90 ° C.).

Further, the pipe P between the condenser 21 and the air inlet 12B in the heat pump unit 2B is provided with a temperature sensor T3 for measuring the temperature of the dry gas D2, and based on the detected value of the temperature sensor T3. The operating state of the compressor 24 is adjusted by an appropriate control device, and is automatically controlled so that the temperature of the dry gas D2 detected by the temperature sensor T3 becomes a predetermined value (for example, 60 ° C.).
Furthermore, the cyclone 17 and the exhaust fan 18 are provided with respect to the pipe line P connected to the exhaust port 14 in the dryer 1.

Further, in this embodiment, surplus heat remaining in the heat medium (steam, drain) used in the temperature raising device 5 with respect to the working water M after releasing heat in the evaporator 23 in the heat pump units 2A, 2B. A heat recovery mechanism 6 for recovering the heat is provided.
As an example, the heat recovery mechanism 6 has the same configuration as the temperature raising mechanism 5, and as shown in FIG. 2B, a plurality of radiating fins 63 are provided on the side periphery of the pipe 62. The heat pump includes a plate fin type heat exchanger 61 that performs heat exchange between a fluid (steam, drain) passing through the pipe 62 and a fluid (working water M) in contact with the radiating fin 63. It is provided with respect to the pipe line P between the units 2A, 2B and the working water tank 4.

In this embodiment, the working water tank 4 is configured such that surplus heat can be recovered from the warm drainage discharged from the peripheral equipment of the drying system S, and the warm drainage is pumped. 42 is configured to pass through a pipe 43 disposed in the working water tank 4.
Here, the peripheral equipment includes not only the peripheral equipment of the drying system S, but also, for example, equipment constituting other production equipment installed in the same factory, and equipment installed in another factory. It shall be.

The drying system S of the present invention is configured as described above as an example, and the operation mode thereof will be described below.
(1) Flow of dry gas First, the flow of the dry gas D that contributes to the drying of the workpiece H will be described.
First, the outside gas is taken in by the blower fan 16A, and then the dry gas D1 is heated by the condenser 21 in the heat pump unit 2A (90 ° C. as an example), and further heated by steam heating by the heating device 5 (one example). As 120 ° C.) and then fed into the dryer 1 through the air supply port 12A.
Thus, according to the present invention, the temperature of the dry gas D1 heated by the heat pump unit 2A using carbon dioxide or the like as a refrigerant can be set to a high temperature state of about 90 ° C., and further the temperature of the dry gas D1 is increased. This is a case where a drying system S to which a fluidized bed dryer or the like is applied as the dryer 1 because the temperature can be raised to the temperature required for the fluidized bed dryer 1 (120 ° C. as an example) by the apparatus 5. However, it is possible to operate efficiently.
Incidentally, when a heat pump unit 2A to which a chlorofluorocarbon refrigerant is applied is used, the temperature of the dry gas D1 raised by the heat pump unit 2A is only about 50 ° C. For this reason, in a drying operation in which it is required to raise the temperature to 120 ° C. by the temperature raising device 5, in the case of a heat pump using a chlorofluorocarbon refrigerant, the contribution rate of the heat pump to the temperature rising energy of the dry gas D1 is reduced, which is efficient. You will not be able to drive properly.

On the other hand, as for the dry gas D2, outside air is taken in by the blower fan 16B, and then the temperature is raised by the condenser 21 in the heat pump unit 2B (60 ° C. as an example), and then sent into the dryer 1 from the air supply port 12B.
The dry gases D1 and D2 that have acted on the object to be processed H are vaporized from the object to be processed H by evaporating volatile components such as moisture, and the temperature is lowered (for example, 66 ° C.). Exhausted.

(2) Action of heat pump unit Here, the temperature raising process of the dry gas D by the heat pump unit 2 will be described.
In the heat pump unit 2, the external heat is taken into the refrigerant (carbon dioxide or the like) in the evaporator 23, the temperature is further raised by the compressor 24, and then the heat is supplied to the dry gas D in the condenser 21. Is raised. And as the external heat source in such an evaporator 23, the working water M supplied from the working water tank 4 is provided, and the working water M supplied to the evaporator 23 is a refrigerant (carbon dioxide or the like). ) Is exhausted from the evaporator 23 in a state where the temperature is lowered due to the loss of energy.

(3) Incorporation of heat into the working water And since the working water M is returned from the evaporator 23 to the working water tank 4, the temperature of the working water M stored in the working water tank 4 is lowered. In order to use this working water M again as a heat source in the heat pump unit 2, it is necessary to raise the temperature again.
For this reason, in the present invention, the amount of heat remaining in the steam or drain discharged from the heat exchanger 51 in the working water M discharged from the evaporator 23 of the heat pump unit 2A and the heat pump unit 2B is converted into the heat recovery mechanism 6 (heat It was made to collect | recover by the exchanger 61).
Further, excess heat is recovered from the warm drainage or the like for the working water M in the working water tank 4 by passing warm drainage or the like discharged from the peripheral equipment of the drying system S through the pipe 43.
Since the working water M heated in this way is sent again to the heat pump unit 2 to be used for raising the temperature of the dry gases D1 and D2, by increasing the thermal energy of the working water M, the heat pump unit 2 The amount of the working water M supplied to can be reduced. As a result, the energy efficiency of the entire drying system S is improved, and operation at a low running cost is possible.

At this time, the working water M in the working water tank 4 passes through the pipe 43 by an appropriate control device (not shown) according to the detected value of the temperature sensor T1 so that the temperature of the working water M is always constant (12 ° C. as an example). The amount of hot wastewater to be adjusted is adjusted.
The heat pump 2 has an optimum operating temperature range for efficient operation, and the temperature of the working water M is set to be close to the optimum operating temperature (for example, 12 ° C.), whereby the heat pump unit 2 Will be operated efficiently. For this reason, the energy efficiency of the whole drying system S improves.

(4) Drying of the object to be processed In the object to be processed H such as food raw material supplied to the dryer 1, a fluidized bed is first formed by the dry gas D1 (120 ° C.) blown from the air inlet 12A. At the same time, volatile components such as moisture are removed.
Eventually, the workpiece H becomes lighter in weight as the drying progresses, gets over the barrier plate 11a, enters the working area of the dry gas D2 (60 ° C.) blown from the air supply port 12B, and further proceeds to the desired drying state. It is in a dry state and is discharged to the outside from the discharge port 15 (the description is omitted here since it is described in [0021]).
On the other hand, the dry gases D1 and D2 after acting on the workpiece H are exhausted to the outside of the dryer 1 from the exhaust port 14, fine powder is removed by the cyclone 17, and then exhausted to the outside.

[Other Examples]
Although the present invention is based on the above-described embodiment, the present invention can take the following forms based on the technical idea of the present invention.

First, the drying system S shown in the basic embodiment described above is configured to include two heat pump units 2, but as illustrated in FIG. 3, the drying system S includes a single heat pump unit 2. Further, although not shown, two or more heat pump units 2 may be provided.
In this case, the drying gas D (90 ° C.) heated in the condenser 21 is branched by branching the pipe P, and one drying gas D is heated to 120 ° C. by the heating device 5 and dried. The gas D1 was supplied to the air inlet 12A. The other dry gas D is adjusted to 60 ° C. by adjusting the amount of outside air mixed by the blower fan 16C based on the detection value of the temperature sensor T3, and is supplied to the air inlet 12B as the dry gas D2. did.

Further, the drying system S shown in the basic embodiment described above is configured to include the heat recovery mechanism 6, but raises the temperature of the working water 4 returned from the evaporator 23 to the working water tank 4. In the case where a separate heat source can be secured, it is possible to adopt a reference form in which the drying system S is configured without providing the heat recovery mechanism 6.
Further, as the heat source of the steam generator that supplies the steam to the temperature raising device 5, surplus heat recovered from the warm drainage discharged from the peripheral equipment of the drying system S may be used.

DESCRIPTION OF SYMBOLS S Drying system 1 Dryer 10 Housing 10a Duct 11 Ventilation plate 11a Dam plate 12 Air supply port 12A Air supply port 12B Air supply port 13 Input port 14 Exhaust port 15 Outlet port 16A Blow fan 16B Blow fan 16C Blow fan 17 Cyclone 18 Exhaust fan 2 Heat pump unit 2A Heat pump unit 2B Heat pump unit 21 Condenser 22 Expansion valve 23 Evaporator 24 Compressor 4 Working water tank 41 Pump 42 Pump 43 Pipe 5 Temperature rising device 51 Heat exchanger 52 Pipe 53 Radiation fin 54 Inlet port 55 Outlet 56 Control valve 6 Heat recovery mechanism 61 Heat exchanger 62 Pipe 63 Radiation fin 64 Inlet 65 Outlet D Drying gas D1 Drying gas D2 Drying gas H Processed substance M Working water P Pipe line T1 Temperature sensor T2 Temperature sensor T3 Temperature sensor T4 temperature sensor

Claims (5)

In a drying system including a dryer and an air supply mechanism for supplying a dry gas to the dryer, the dryer is a continuous hot air dryer, and the air supply mechanism includes a heat pump unit. Further, the air supply mechanism is provided with a temperature raising device for further raising the temperature of the dry gas heated by the heat pump unit, and acts as a heat source supplied to the evaporator in the heat pump unit. A drying system comprising a heat pump unit and a temperature raising device , wherein a heat recovery mechanism is provided for collecting heat remaining in the heat medium used in the temperature raising device in water . Drying system of the working water, equipped with a heat pump unit and a heated apparatus as claimed in claim 1, wherein the arrangement for raising the temperature by been heated effluent discharged from the peripheral equipment is provided. 3. A drying system comprising a heat pump unit and a temperature raising device according to claim 1, wherein the working water supplied to the evaporator in the heat pump unit is adjusted to an optimum operating temperature range of the heat pump unit. . 4. A drying system comprising the heat pump unit according to claim 1, 2 or 3, and a temperature raising device, comprising a plurality of the heat pump units. The said heat pump unit uses a carbon dioxide as a refrigerant | coolant, The drying system provided with the heat pump unit and temperature rising apparatus of Claim 1, 2, 3 or 4 characterized by the above-mentioned.

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