JP6941792B2 - Sludge dryer - Google Patents

Description

The present invention relates to a drying device for drying an object to be treated, and is particularly used for drying sludge discharged from a factory.

Sludge called sludge containing various inorganic substances is generated from the production equipment of the factory. This sludge may be discarded or reused. In both cases, transportation is required, and it is inefficient to transport sludge containing more than half of the water as it is, so it is necessary to dry this sludge first.

Examples of the device for drying the object to be treated include Patent Document 1. See FIG. This is a device for drying foods and the like, and dries the object to be dried 106 in the drying chamber 101 while circulating air between the drying chamber 101 and the dehumidifying dryer 103. Reference numeral 102 is an air duct, reference numeral 104 is a waveguide, reference numeral 105 is a μ wave generator, reference numeral 107 is a reflected power measuring instrument, reference numeral 108 is a wiring, reference numeral 109 is a control circuit, reference numeral 127 is moist air, and reference numeral 128. Is outside air, reference numeral 130 is a valve, and reference numeral 131 is a temperature sensor.

When the temperature inside the drying chamber 101 rises by this method, the temperature of the air is detected by the temperature sensor 131, and when the temperature inside the drying chamber 101 rises more than necessary, the control circuit 109 is provided in the air duct 102. The valve 130 is opened and closed, and the relatively dry outside air 128 is taken into the dehumidifying dryer 103 to lower the temperature of the circulating air.

Japanese Unexamined Patent Publication No. 08-178522

The drying device described in Patent Document 1 has a structure in which outside air 128 is introduced when the temperature of the circulating drying air rises. However, in such a structure, in winter when the outside air temperature is low, the low temperature outside air 128 is directly introduced into the dehumidifying dryer 103. In the dehumidifying dryer 103, the air taken in during dehumidification is dehumidified by expanding the refrigerant of the heat pump to lower the temperature and condensing the moisture in the air. Therefore, when the temperature of the introduced air is low, there is a problem that the moisture condensed in the dehumidifying dryer 103 freezes and the dehumidifying and drying ability is remarkably lowered.

In particular, since sludge such as sludge is generated in a large amount, the drying device itself is often placed outdoors. Therefore, in winter, the outside air temperature becomes low, and the above problems are likely to occur frequently.

The present invention has been conceived in view of the above problems, and provides a sludge drying device that does not freeze in the dehumidifying dryer even when the outside air temperature is low.

More specifically, the sludge drying device according to the present invention is
The bottom surface is composed of a filter that can hold sludge and is breathable, and the top surface is a drying container provided with a suction opening, an outside air intake opening, and an exhaust opening.
A dehumidifying dryer that sucks the air in the drying container from the suction opening and sends out a drying air that dehumidifies the air.
A blower chamber arranged below the drying container and sending the drying air to the drying container,
It is characterized by having an exhaust fan connected to the exhaust opening and exhausting the air in the drying container.

When the outside air temperature is low, the sludge drying device according to the present invention dries the object to be treated (sludge) while circulating air between the drying container and the dehumidifying dryer. Then, when the temperature of the circulating air rises, the outside air is taken into the drying container and the mixed gas of the air and the outside air in the drying container is returned to the dehumidifying dryer, so even if the temperature of the outside air is low, Moisture does not freeze in the expansion part of the dehumidifying dryer.

In addition, since it is not necessary to change the operation method on the dehumidifying / drying machine side according to the temperature of the gas to be taken in, a general-purpose dehumidifying / drying machine can be used as it is, which has the effect of reducing the cost as a sludge drying device. Also occurs.

It is a figure which shows the structure of the sludge drying apparatus which concerns on this invention. It is a top view of the lid body of a drying container. It is a detailed view of a drying container. It is a figure explaining the 1st operation mode (when the outside air temperature is high). It is a figure explaining the 2nd operation mode (when the outside air temperature is low). It is a flow chart which shows the processing main processing of a controller. It is a flow chart which shows the process of the 1st operation mode. It is a flow chart which shows the processing of the 2nd operation mode. It is a figure which shows the structure of the conventional drying apparatus.

The sludge drying apparatus according to the present invention will be described below with reference to the drawings. The following description describes one embodiment of the present invention, and the present invention is not limited to the following description. That is, the following embodiments can be modified as long as they do not deviate from the gist of the present invention.

FIG. 1 shows the configuration of the sludge drying apparatus according to the present invention. The sludge drying device 1 is basically composed of a drying container 10, a dehumidifying dryer 12, a blower chamber 14, an exhaust fan 16, a thermometer 18, and a controller 20, and is provided with an outside air thermometer 19. You may.

The drying container 10 is a container in which sludge 50 is put and dried. It usually has a rectangular parallelepiped shape. The material is not particularly limited, but is formed of a material having high corrosion and weather resistance, which is obtained by applying a corrosion resistant coating to iron. This is because the sludge 50 itself may contain an acidic or alkaline solution.

The drying container 10 usually has a rectangular parallelepiped shape. This is because it is easy to manufacture. However, the shape is not particularly limited to a rectangular parallelepiped, and a shape other than a rectangular parallelepiped may be used. Here, the description will be continued assuming that it has a rectangular parallelepiped shape.

A lid 10a is prepared in the drying container 10. The lid body 10a is provided with three openings, a suction opening 10aa, an outside air intake opening 10ab, and an exhaust opening 10ac. The suction opening 10aa is provided in the center of the lid 10a. An outside air intake opening 10ab and an exhaust opening 10ac are formed with the suction opening 10aa interposed therebetween.

FIG. 2 shows a state in which the lid body 10a is viewed in an upward plan view. In this way, by providing the suction opening 10aa for the dehumidifying dryer 12, which will be described later, in the center of the lid 10a, the air in the drying container 10 can be sucked up evenly. Further, by separating the outside air intake opening 10ab and the exhaust opening 10ac, a shortcut of the outside air can be prevented, and the outside air and the air in the drying container 10 can be sufficiently mixed to reduce temperature unevenness and dehumidify the dryer 12 Can be returned to. As a result, the water does not freeze in the expansion portion 12a of the dehumidifying dryer 12 even if the outside air at a lower temperature is taken in.

See FIG. 1 again. The return pipe 12c of the dehumidifying dryer 12 is airtightly connected to the suction opening 10aa. The suction pipe 16c of the exhaust fan 16 is airtightly connected to the exhaust opening 10ac. A sealing lid 11 is provided for the outside air intake opening 10ab (see also FIG. 2). The sealing lid 11 is usually opened and closed manually. However, the controller 20 described later may open and close the sealing lid 11.

FIG. 3 shows a detailed view of the drying container 10. With reference to FIG. 3A, the bottom surface 10b of the drying container 10 is formed of a frame body 10ba and a filter 10bb. The filter 10bb is made of a breathable material while being able to retain the sludge 50. Specifically, a metal sheet member or the like having a through hole of about 1 to several millimeters can be preferably used.

The bottom surface 10b is composed of a plurality of parts and can be opened and closed downward from the center to the double doors. More specifically, with reference to FIG. 3B, the bottom surface 10b is composed of the door 30 and the door 32. The door 30 and the door 32 are connected to the opposite sides of the bottom surface 10b by a hinge 31 and a hinge 33. The door 30 and the door 32 are arranged with an opening / closing means 34 and an opening / closing means 36 for opening / closing, respectively.

Therefore, by operating the opening / closing means 34 and the opening / closing means 36, the bottom surface 10b opens downward in a double door, and the sludge 50 dried in the drying container 10 falls directly below. That is, the sludge 50 can be easily taken out and can be taken out in a short time.

See FIG. 1 again. The dehumidifying dryer 12 is a device that removes moisture from the sucked air and sends out drying air. The expansion portion 12a is arranged on the suction side, and the compression portion 12b is arranged on the discharge side. The suction side is airtightly connected to the suction opening 10aa of the drying container 10 via the return pipe 12c.

On the suction side, not only the return pipe 12c is connected, but also outside air can be directly taken in, and a direct suction port 12e is also provided. Further, the compression unit 12b on the discharge side is connected to the blower chamber 14 described later via the feed pipe 12d.

The dehumidifying dryer 12 causes the sucked air to rapidly expand in the expansion portion 12a and exchange heat with a refrigerant whose temperature has dropped, thereby causing moisture in the air to condense on the metal fins constituting the heat exchanger. Removes moisture in the air. The air from which the moisture has been removed is converted into high-temperature and low-humidity air by heat exchange with the refrigerant that has been compressed again by the compression unit 12b and has become hot, and becomes "dry air Da". A heater for heating air may be separately prepared in the compression unit 12b.

The blower chamber 14 is a container that creates a buffer space that is detachably connected below the drying container 10. As for the shape, a rectangular parallelepiped similar to the drying container 10 can be preferably used. Of course, it may have a shape other than a rectangular parallelepiped. However, it is desirable that the drying container 10 has a structure that can be airtightly connected to the bottom surface 10b. Here, the description will be continued as a rectangular parallelepiped shape.

The upper surface 14a of the ventilation chamber 14 is open, and the air blowing chamber 14 is formed of four side walls and a bottom surface. One of the side walls is provided with an insertion port 14i for drying air Da. The insertion port 14i is airtightly connected to the feed pipe 12d of the dehumidifying dryer 12. Therefore, the dry air Da sent into the air blowing chamber 14 from the insertion port 14i is sent from the opened upper surface 14a toward the bottom surface 10b of the drying container 10.

The exhaust fan 16 is a device that sends air from the suction side to the exhaust side. In the sludge drying device 1, it is used as an air pump for discharging air from the drying container 10. The suction side of the exhaust fan 16 is airtightly connected to the exhaust opening 10ac of the drying container 10 by a suction pipe 16c.

The thermometer 18 is arranged in the return pipe 12c connecting the expansion portion 12a of the dehumidifying dryer 12 from the suction opening 10aa of the drying container 10. This is to measure the temperature of the air returning from the drying container 10 to the dehumidifying dryer 12. The outside air thermometer 19 is a thermometer that measures the outside air temperature.

The controller 20 controls the entire operation of the sludge drying device 1. As the controller 20, a computer composed of an MPU (Micro Processor Unit) and a memory can be preferably used. The controller 20 is connected to at least a thermometer 18 and an exhaust fan 16. Further, it may be connected to the dehumidifying dryer 12 and the outside air thermometer 19 to control the operating state and the switching between the direct suction port 12e and the return pipe 12c. When the electric opening / closing mechanism of the sealing lid 11 is provided, it may be connected to the electric opening / closing mechanism of the sealing lid 11.

The operation of the sludge drying device 1 having the above configuration will be described. See FIG. FIG. 4 shows an operating state when the outside air temperature is high. In this case, the drying air Da produced by the dehumidifying dryer 12 is sent to the drying container 10, and the air Wa that has absorbed the moisture in the sludge 50 is discharged to the outside by the exhaust fan 16.

More specifically, first, a certain amount of moist sludge 50 is put into the drying container 10. The wet sludge 50 is held by the filter 10bb (see FIG. 3A) on the bottom surface 10b and does not fall into the lower blowing chamber 14. When the operation is performed in the state shown in FIG. 4, the outside air intake opening 10ab is closed by the sealing lid 11. Further, in the dehumidifying dryer 12, the direct suction port 12e is selected instead of the return pipe 12c. In FIG. 4, the return pipe 12c is shown by a dotted line, showing a state in which it is not used.

When the dehumidifying dryer 12 starts to operate, the outside air Fa is directly taken in from the suction port 12e, and the drying air Da dehumidified and heated by the expanding portion 12a and the compressing portion 12b is sent from the sending pipe 12d to the blowing chamber 14. In the blower chamber 14, the dry air Da sent from the insertion port 14i diffuses into the blower chamber 14. The dry air Da diffused in the blower chamber 14 enters the drying container 10 from the entire bottom surface 10b of the drying container 10.

The dry air Da that has entered the drying container 10 passes through the moist sludge 50 and flows toward the lid 10a of the drying container 10. At this time, the dry air Da removes the water in the sludge 50. The air Wa that has absorbed the moisture is sucked by the exhaust fan 16 from the exhaust opening 10ac of the lid body 10a through the suction pipe 16c and is discharged to the outside. Such operation is called a first operation mode.

The controller 20 determines the operating state of the dehumidifying dryer 12 and the exhaust fan 16 so as to balance the amount of the drying air Da sent out from the dehumidifying dryer 12 and the amount of exhaust air from the exhaust fan 16.

In FIG. 4, the dehumidifying dryer 12 directly takes in the outside air Fa to dehumidify. The dehumidifying operation in the expansion unit 12a is performed by expanding the refrigerant in the heat pump at once to lower the temperature, and by exchanging heat with the low temperature refrigerant to condense moisture in the air to dehumidify. At this time, the temperature of the air drops by about 15 ° C. at once. Therefore, when the temperature of the air taken into the expansion portion 12a itself is lower than 15 ° C., the temperature of the air falls below 0 ° C. in the process of dehumidification.

Then, the moisture condensing on the surface of the aluminum fins, for example, which constitutes the expansion portion 12a, freezes. As a result, the heat exchange efficiency deteriorates and the dehumidifying function deteriorates.

Therefore, the sludge drying device 1 according to the present invention switches to the operation mode shown in FIG. 5 when the temperature of the outside air Fa taken into the expansion portion 12a falls below a constant temperature (for example, the above 15 ° C.).

See FIG. In FIG. 5, the dehumidifying dryer 12 switches so that air is taken into the expansion portion 12a by the return pipe 12c. In FIG. 5, it is indicated by a dotted line that the direct suction port 12e is not used. This switching may be performed by the controller 20. Next, the sealing lid 11 is opened. That is, the outside air intake opening 10ab is opened.

In this state, the sludge drying device 1 starts operation. It is assumed that the wet sludge 50 has already been put into the drying container 10. The dehumidifying dryer 12 takes in the air in the drying container 10 into the expanding portion 12a via the return pipe 12c, passes it through the compressing portion 12b, dehumidifies and heats it, and sends it from the sending pipe 12d to the blowing chamber 14 as drying air Da. ..

The dry air Da sent into the air blowing chamber 14 enters the drying container 10 from the entire surface of the bottom surface 10b of the drying container 10 and removes the moisture of the moist sludge 50. The air Wa that has absorbed the moisture is returned to the dehumidifying dryer 12 through the return pipe 12c from the suction opening 10aa of the lid body 10a.

In this operating mode, air circulates between the drying container 10 and the dehumidifying dryer 12. Further, the temperature of the supplied dry air Da rises to nearly 60 ° C. Therefore, the temperature of the air gradually rises during circulation. However, if the temperature of the air is too high, the temperature of the refrigerant also rises, the dehumidifying effect of the expansion portion 12a becomes low, and efficient dehumidification cannot be performed.

Therefore, when the temperature of the air in the return pipe 12c exceeds a certain level, the exhaust fan 16 is operated. When the exhaust fan 16 is operated, the air Wa that has absorbed a certain amount of water in the drying container 10 is discharged to the outside. Then, the same amount of outside air Fa as discharged is introduced into the drying container 10 through the outside air intake opening 10ab.

The air in the drying container 10 mixed with the outside air Fa becomes air Wa that has absorbed moisture, passes through the return pipe 12c, and is sent to the expansion portion 12a of the dehumidifying dryer 12. That is, while the exhaust fan 16 is operating, a part of the air circulating between the drying container 10 and the dehumidifying dryer 12 is replaced with the outside air Fa. As a result, the temperature of the circulating air drops, but it does not drop to the outside air temperature at once.

The temperature of the air taken into the expansion unit 12a is constantly monitored by the thermometer 18. Therefore, when the temperature of the circulating air falls below a certain value, the exhaust fan 16 is stopped. As described above, when the outside air temperature is too low, air can be circulated between the drying container 10 and the dehumidifying dryer 12 to continue the operation so that the condensed moisture in the expansion portion 12a does not freeze.

Further, when cooling the circulating air, the outside air Fa is once taken into the drying container 10, mixed with the air in the drying container 10 and then returned to the dehumidifying dryer 12, so that the moisture freezes in the dehumidifying dryer 12. Can be avoided. The operation mode described with reference to FIG. 5 is referred to as a second operation mode.

When the wet sludge 50 is dried in the sludge drying device 1 for a predetermined time, most of the water is removed. After drying for a predetermined time, the dehumidifying dryer 12 and the exhaust fan 16 are stopped. Next, the drying container 10 is picked up and carried to a predetermined position, where the bottom surface 10b is opened. Since the bottom surface 10b opens in a double door, all the sludge 50 in the drying container 10 is discharged (see also FIG. 3). The procedure for discharging the sludge 50 does not change between the first operation mode and the second operation mode.

FIG. 6 summarizes the processing flow of the controller 20. The operation mode may be changed manually according to the season, but the case of checking the external temperature with the outside air thermometer 19 will be described below. When the sludge drying device 1 starts operation (step S100), the end determination is performed (step S102). The end determination may be whether or not a certain time has passed from the operation start time, or may be an instruction by the emergency stop button. When it ends (Y branch in step S102), it stops (step S120). If it does not end (N branch in step S102), the external temperature Tc is confirmed (step S104). The external temperature Tc can be confirmed by the outside air thermometer 19.

Next, the external temperature Tc and the threshold temperature Th0 are compared (step S106). Then, when the external temperature Tc is higher than the threshold temperature Th0 (Y branch in step S106), the first operation mode is performed (step S108), otherwise (N branch in step S106) the second operation mode is performed ( Step S110).

Here, the first operation mode is the operation described with reference to FIG. 4, and the second operation mode is the operation described with reference to FIG. Therefore, the threshold temperature Th0 is a temperature at which moisture freezes in the expansion portion 12a when the outside air Fa is directly introduced into the expansion portion 12a of the dehumidifying dryer 12. Generally, the temperature is about 13 ° C to 17 ° C.

The process that has advanced to the first operation mode (step S108) and the second operation mode (step S110) performs a series of processes in each mode, and then returns to the end determination of step S102 to stop the process or process. Continuation is judged.

FIG. 7 shows a flow of processing in the first operation mode. When the processing of the first operation mode is started (step S200), the operation setting is performed such that the sealing lid 11 is closed and the intake of the expansion portion 12a of the dehumidifying / drying device 12 is directly switched to the suction port 12e (step S202). Note that step S200 is the same as step S108 shown in FIG. Further, the operation setting (step S202) may be skipped if it has already been set.

Next, the amount of dry air Da sent out from the feed pipe 12d by the compression unit 12b and the amount of exhaust gas discharged by the exhaust fan 16 are adjusted to be constant (step S204). This amount varies depending on the external temperature Tc and the performance of the dehumidifying dryer 12. Therefore, it is preferable to adjust the operating state of the exhaust fan 16 according to the operating state of the dehumidifying dryer 12. Then, the flow is transferred to the main process of FIG. 6 (step S206). That is, the process returns to the main step S102.

FIG. 8 shows the processing flow of the second operation mode. When the second operation mode is started (step S300), the operation setting is performed (step S302). The operation setting here is a process of opening the sealing lid 11 and switching the intake of the expansion portion 12a of the dehumidifying dryer 12 to the return pipe 12c. If the operation setting (step S302) has already been performed, this process may be skipped.

Next, the temperature Tr of the air in the return pipe 12c is confirmed (step S304). Then, the high temperature set temperature Th1 and the low temperature set temperature Th2 are compared with the temperature Tr (step S306 and step S308).

If the air temperature Tr in the return pipe 12c is higher than the high temperature set temperature Th1 (Y branch in step S306), it is necessary to lower the temperature of the circulating air, so the exhaust fan 16 is put into an operating state (step S310). .. At this time, it goes without saying that the delivery amount of the dehumidifying dryer 12 and the exhaust amount of the exhaust fan 16 are the same.

Further, when the air temperature Tr in the return pipe 12c is lower than the high temperature set temperature Th1 (N branch in step S306) and lower than the low temperature set temperature Th2 (Y branch in step S308), the temperature Tr of the circulating air is low. Since it is too much, the operation of the exhaust fan 16 is stopped (step S312).

Further, when the air temperature Tr in the return pipe 12c is lower than the high temperature set temperature Th1 (N branch in step S306) and higher than the low temperature set temperature Th2 (N branch in step S308), the temperature Tr of the circulating air is appropriate. It is determined that it is a value, and the process is returned to the main (step S314).

As described above, the sludge 50 can be dried by the sludge drying device 1. Further, the sludge drying device 1 is configured so as not to freeze in the expansion portion 12a of the dehumidifying dryer 12, and the sludge 50 can be dried even in a cold region or outdoors in winter. In addition, the load on the dehumidifying dryer is reduced in the second operation mode as compared with the first operation mode to save energy, and the operation time in the second operation mode can be lengthened.

The sludge drying apparatus according to the present invention can be suitably used for drying industrially generated sludge.

1 Sludge drying device 10 Drying container 10a Lid 10aa Suction opening 10ab Outside air intake opening 10ac Exhaust opening 10b Bottom 10ba Frame 10bb Filter 11 Sealed lid 12 Dehumidifying dryer 12a Expanding part 12b Compressing part 12c Return pipe 12e Direct suction port 12d Feed pipe 14 Blower chamber 14a Top surface 14i Insertion port 16 Exhaust fan 16c Suction pipe 18 Thermometer 19 Outside air thermometer 20 Controller 30 Door 32 Door 31 Hinge 33 Hinge 34 Opening and closing means 36 Opening and closing means 50 Sludge Da Dry air Wa Moisture sucked Air Fa Outside air Tc External temperature Th0 Threshold temperature Tr (of air in return pipe 12c) Temperature Th1 High temperature set temperature Th2 Low temperature set temperature

Claims (3)

The bottom surface is composed of a filter that can hold sludge and is breathable, and the top surface is a drying container provided with a suction opening, an outside air intake opening, and an exhaust opening.
A dehumidifying dryer that sucks the air in the drying container from the suction opening and sends out a drying air that dehumidifies the air.
A blower chamber arranged below the drying container and sending the drying air to the drying container,
A sludge drying device having an exhaust fan connected to the exhaust opening and exhausting the air in the drying container. The sludge drying device according to claim 1, wherein the bottom surface of the drying container can be opened and closed downward with a double door. A thermometer that measures the temperature of the air sucked by the dehumidifying dryer, and
The sludge drying apparatus according to claim 1 or 2, further comprising a controller that controls the operation of the exhaust fan based on the temperature of the thermometer.

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