JP5550841B2 - Drying system with heat pump unit - Google Patents

Description

  The present invention relates to a drying apparatus including a heat pump unit, and particularly relates to a drying system including a heat pump unit that can efficiently operate a dryer that requires high-temperature drying gas.

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. As a result, long-time processing is possible.
For this reason, a heat pump unit using a chlorofluorocarbon refrigerant (the temperature of the hot air obtained is about 50 ° C.) can be applied, but it is not realistic to apply it to other dryers.
Specifically, for example, in a fluidized bed dryer, the residence time (processing time) of the object to be processed in the dryer is short, and a large amount of heat is required at the initial stage of drying. The heat pump using this refrigerant cannot obtain the necessary amount of heat, so that it cannot be operated efficiently, and the cost is increased.

Further, from the viewpoint of so-called energy saving, it has been generally performed to reuse waste heat in a drying apparatus. However, in order to do so, the acted dry gas (exhaust gas) requires a certain treatment in order to effectively act as a drying medium again.
Specifically, in order to dehumidify the dry gas that has already been actuated and further raise the temperature so that it can be circulated and reused again as a dry gas, treatment by a dehumidifying device or a temperature raising device is required. For this reason, although a part of the exhaust heat is reused, it is not energy efficient, leading to an increase in size of the apparatus, and it is difficult to avoid corrosion and scale adhesion due to the circulation of dry gas. .

Japanese Patent No. 3957665

  The present invention has been made in view of such a background, and the heat pump is used as a heat source for a continuous dryer such as a fluidized bed dryer by utilizing the exhaust heat for stabilizing the heat source of the heat pump unit. The technical challenge is to develop a drying system that includes a new heat pump unit that makes it possible to apply the unit and that is highly energy efficient and that can perform more stable operation.

That is, the drying system including the heat pump unit according to claim 1 is an operation as a heat source medium to be supplied to the evaporator in the heat pump unit in the drying system in which the drying gas supplied to the dryer is heated by the condenser in the heat pump unit. water, along with those fixed amount stored is recycled, the effect water is shall be heated by waste heat of the discharged action already dried gas from the dryer, this time, the drying gas By adjusting the amount of dry gas flowing into the heat exchanger for exchanging heat between the working water and the working water according to the detection value of the temperature sensor provided in the working water tank, the working water is converted into the heat pump unit. adjusted to the optimum operating temperature range, whereby a is supplied to the evaporator effect water with a constant water temperature in the heat pump unit Turkey Those made as a feature.

  In addition to the above requirements, the drying system including the heat pump unit according to claim 2 is characterized in that the heat pump unit uses carbon dioxide as a refrigerant.

  Furthermore, a drying system comprising a heat pump unit according to claim 3 is characterized in that, in addition to the above requirements, the drying gas heated by the heat pump unit is further heated and supplied to the dryer. is there.

  Furthermore, the drying system provided with the heat pump unit according to claim 4 is characterized in that a plurality of the heat pump units are provided in addition to the above requirements.

Furthermore, the drying system comprising the heat pump unit according to claim 5 is characterized in that, in addition to the above requirements, the dry gas is exhausted to the outside after the working water as the heat source medium is heated. is there.
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 present invention, the working water as the heat source medium of the heat pump unit effectively absorbs the exhaust heat of the dry gas that has been acted, and is circulated and used after being heated to a certain temperature. For this reason, since the energy efficiency of the whole drying system is good and working water is circulated and used, the consumption of working water can be remarkably reduced, and operation at low cost is possible.
Furthermore, since the temperature of the working water supplied to the heat pump unit is constant, it is possible to perform stable operation while suppressing fluctuations in the load on the compressor.
In addition, the heat pump unit can be operated efficiently.

  According to the invention described in claim 2, the temperature of the drying gas heated by the heat pump unit can be about 90 ° C., and a continuous dryer such as a fluidized bed dryer can be applied as the dryer. It becomes possible.

  Moreover, according to the invention of Claim 3, favorable drying according to the property of a to-be-processed object and the structure of dryer can be performed.

  Moreover, according to the invention of Claim 4, favorable drying according to the property of to-be-processed object and the structure of dryer can be performed.

  According to the invention described in claim 5, since the dry gas is not circulated, a device for performing a series of operations such as cooling, dehumidification, and reheating becomes unnecessary, and the device configuration can be simplified. Moreover, corrosion and scale adhesion can be avoided.

It is a block diagram which shows the drying system provided with the heat pump unit of this invention. It is a skeleton figure showing an exhaust heat recovery device.

  Although the form of the drying system provided with the heat pump unit of the present invention is as shown in the following examples, it is possible to appropriately modify this example within the scope of the technical idea of the present invention.

As shown in FIG. 1, a drying system S including a heat pump unit of the present invention (hereinafter referred to as a drying system S) includes a dryer 1, a heat pump unit 2, an exhaust heat recovery device 3, and a working water tank 4. As a main element. In this embodiment, a temperature raising device 5 is provided in addition to these devices.
Further, the drying system S of the present invention is based on the continuous dryer 1 in which the residence time (processing time) of the workpiece H in the dryer 1 is short and a large amount of heat is required in the initial stage of drying. The drying process 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, as the dryer 1, a continuous dryer is applied as an example, and in this embodiment, a fluidized bed dryer is applied.
In this apparatus, the inside of the housing 10 is used as a processing space for drying, and a drying gas D is supplied from below the ventilation plate 11 provided so as to divide the processing space into upper and lower portions. Drying is performed while a fluidized bed is formed on the workpiece H located in the area.
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.

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. Those using carbon as a refrigerant are employed.
When a plurality of heat pump units 2 are provided, the heat pump units 2 and peripheral devices are distinguished from each other by adding alphabetic capital letters to the reference numerals.

Next, the exhaust heat recovery device 3 will be described. This device acts on the workpiece H, and then takes in the heat (exhaust heat) of the dry gas D discharged from the dryer 1 into the working water M. It is.
Specifically, as shown in FIG. 2, a heat exchanger 31 and a silencer 32 are connected in series by a pipe P to form a flow path of the dry gas D, and the dry gas D is further subjected to heat exchange. A bypass line 33 is provided for taking a path that does not pass through the vessel 31 and the silencer 32.
As an example of the heat exchanger 31, a plurality of heat radiation fins 31b are provided on the side periphery of the pipe 31a, and a fluid (working water M) passing through the pipe 31a and a fluid in contact with the heat radiation fin 31b (dry gas D). A plate fin type device that performs heat exchange between the two is applied.
The bypass line 33 is provided with a damper 33a so that the amount of dry gas D flowing into the bypass line 33 can be adjusted.

As shown in FIG. 1, a drying system S is configured by combining the dryer 1, the heat pump unit 2, the exhaust heat recovery device 3, and the working water tank 4.
First, 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 a 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.

  Further, the exhaust port 14 in the dryer 1 and the input side of the heat exchanger 31 in the exhaust heat recovery device 3 (the flow path on the heat radiation fin 31b side) are connected by a pipe P. For P, a cyclone 17 and an exhaust fan 18 are provided.

  The both ends of the pipe 31a of the heat exchanger 31 in the exhaust heat recovery device 3 are connected to the working water tank 4 by the pipe P, and the pump 42 is provided between the input side of the pipe 31a and the working water tank 4. Is provided.

The drying system S of the present invention is based on the above-described configuration, but in this embodiment, the temperature raising device 5 is further provided.
That is, in this embodiment, drying gases D1 and D2 having different temperatures with respect to the dryer 1 are respectively supplied to the air inlets 12A and 12B, and the fluidized bed dryer as the dryer 1 has a high temperature. Since the dry gas D is required, a configuration in which the temperature of the dry gas D1 heated by the heat pump unit 2A is further raised by the temperature raising device 5 is adopted.
Specifically, as an example, a plurality of radiating fins 51b are provided on the side periphery of the pipe 51a, and heat is generated between a fluid (steam) passing through the pipe 51a and a fluid (dry gas D1) in contact with the radiating fins 51b. A plate fin type heat exchanger 51 for exchanging is provided for the pipe line P between the heat pump unit 2 </ b> A and the dryer 1.
The heat exchanger 51 is supplied with steam from an appropriate steam generator (not shown), and is provided with a control valve 52 for adjusting the amount of steam.
The pipe P between the heat exchanger 51 and the air supply port 12A is provided with a temperature sensor T2 for measuring the temperature of the dry gas D1, and an appropriate value is determined based on the detected value of the temperature sensor T2. The opening degree of the control valve 52 is adjusted by the control device.
Furthermore, a temperature sensor T3 for measuring the temperature of the dry gas D2 is provided in the pipe line P between the condenser 21 and the air supply port 12B in the heat pump unit 2B.

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.
The dry gas D is first taken in by the blower fan 16 and then heated by the condenser 21 in the heat pump unit 2 (for example, the dry gas D1 is set to 90 ° C. and the dry gas D2 is set to 60 ° C.). Accordingly, the temperature is raised by steam heating by the temperature raising device 5 (for example, the dry gas D1 is set to 120 ° C.), and then sent to the dryer 1 to make the processing space dry.
And the dry gas D which acted on the to-be-processed object H is exhausted to the exterior of the dryer 1 from the exhaust port 14 in the state (66 degreeC as an example) in which the temperature fell further.
Thus, since the dry gas D is in a high temperature state in the exhausted state, calories for serving as a heat source are sufficiently maintained.

(2) Temperature rise of dry gas by heat pump unit Here, the temperature rise process of the dry gas D by the heat pump unit 2 will be described.
In the heat pump unit 2, the temperature is raised by taking external heat into the refrigerant in the evaporator 23 and supplying the taken heat to the dry gas D in the condenser 21. And as an 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 (12 ° C. as an example) supplied to the evaporator 23 is The refrigerant 23 is discharged from the evaporator 23 in a state where the temperature is lowered due to the evaporation of the refrigerant (carbon dioxide) (for example, 7 ° C.).

(3) Temperature rise of working water by exhaust heat recovery device And since the working water M is returned to the working water tank 4 from the evaporator 23, the temperature of the working water M stored in the working water tank 4 decreases. However, 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 (as an example, 12 ° C.).
For this reason, in the present invention, the working water M in the working water tank 4 is once supplied to the exhaust heat recovery device 3, and the temperature is raised using the exhaust heat of the dry air D.

That is, in the exhaust heat recovery device 3, the dry gas D flows into the heat exchanger 31, heat exchange is performed with the working water M sent from the working water tank 4, and the working water M is heated. (21.9 ° C. in this example).
The working water M that has absorbed the exhaust heat of the dry gas D is returned to the working water tank 4, mixed with the working water M (7 ° C.) returned from the heat pump unit 2, and sent to the heat pump unit 2 again. Then, the dried gas D1, D2 is subjected to a temperature increase.

At this time, the temperature of the working water M in the working water tank 4 is always constant (12.0 ° C. as an example), and the heat is exhausted by an appropriate control device (not shown) according to the detected value of the temperature sensor T1. The opening degree of the damper 33a in the recovery device 3 is adjusted, and the amount of the dry gas D flowing into the heat exchanger 31 is adjusted.
The temperature of the working water M is set to be within the optimum operating temperature range (for example, 12 ° C.) because the heat pump has an optimum operating temperature range of the endothermic heat source for efficient operation. The heat pump unit 2 is operated efficiently.

(4) Drying of the object to be processed As for 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. , Moisture is removed.
Eventually, the weight of the object to be processed H becomes light as the drying progresses, gets over the barrier plate 12a, 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 becomes a dry state and is discharged | emitted from the discharge port 15 outside.
On the other hand, the dry gases D1 and D2 after acting on the workpiece H are exhausted from the exhaust port 14 to the outside of the dryer 1, fine powder is removed by the cyclone 17, and then supplied to the exhaust heat recovery device 3. .

[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 was a fluidized bed dryer applied as the dryer 1, but as the dryer 1, the so-called band dryer described in the background art, Various drying apparatuses can also be applied.

In addition, the drying system S shown in the basic embodiment described above is configured to include two heat pump units 2, but one or two or more multiple machines are provided depending on the requirements of the dryer 1. You may make it provide.
Similarly, a refrigerant other than carbon dioxide may be used as the refrigerant of the heat pump unit 2 according to the request of the dryer 1.
Similarly, the drying system S may be configured without providing the temperature raising device 5 according to the request of the dryer 1.

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 Exhaust port 16A Blow fan 16B 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 3 Waste heat recovery device 31 Heat exchanger 31a Pipe 31b Radiation fin 32 Moisture removal device 33 Bypass pipe 33a Damper 4 Working water tank 41 Pump 42 Pump 5 Temperature raising device 51 Heat exchanger 51a Pipe 51b Radiation fin 52 Control valve D Drying gas D1 Drying gas D2 Drying gas H Processed object M Working water P Pipe line T1 Temperature sensor T2 Temperature sensor T3 Temperature sensor

Claims (5)

In the drying system in which the temperature of the drying gas supplied to the dryer is raised by the condenser in the heat pump unit, the working water as the heat source medium supplied to the evaporator in the heat pump unit is circulated and used in a certain amount. the effect water is shall be heated by waste heat of the discharged action already dried gas from the dryer, this time, heat exchange for exchanging heat between the working solution and the dry gas By adjusting the amount of dry gas flowing into the vessel according to the detection value of the temperature sensor provided in the working water tank, the working water is adjusted to the optimum operating temperature range of the heat pump unit, thereby constantly maintaining a constant water temperature. drying system comprising a heat pump unit which acts water is characterized and Turkey is supplied to the evaporator in the heat pump unit.
2. The drying system comprising a heat pump unit according to claim 1, wherein the heat pump unit uses carbon dioxide as a refrigerant.
3. The drying system comprising the heat pump unit according to claim 1, wherein the drying gas heated by the heat pump unit is further heated and supplied to the dryer.
4. The drying system comprising a heat pump unit according to claim 1, wherein a plurality of the heat pump units are provided.
  5. The drying system comprising a heat pump unit according to claim 1, wherein the drying gas is exhausted to the outside after raising the temperature of the working water as a heat source medium.

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