JP2006010254A - Drying system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize steam supplied from a steam generation source 7 during cooling and unloading after drying is completed in a drying system that supplies steam to a dryer 5 to dry a material to be dried by a batch processing method. Increase drying efficiency.
SOLUTION: A predrying chamber 1 for predrying prior to a drying process is provided, the exhaust temperature from a dryer 5 is detected to detect the completion of drying of the material to be dried, and after the detection, the material to be dried is dried. The steam supplied from the steam supply source 7 is supplied to the preliminary drying chamber 1 until the delivery from the container 5 is completed, and a preliminary drying process is performed on the material to be dried.
[Selection] Figure 1

Description

  The present invention relates to a drying system that reduces food residue, sludge, and the like by drying.

In a conventional drying system, for example, the following drying process is performed in a dryer provided in a waste incinerator.
The wet waste is passed through the preheater and then sent to the dryer. In the dryer, the waste and the moisture contained therein are superheated by the superheated steam, and the water is evaporated as generated steam and mixed with the superheated steam. Further, the mixed steam is regenerated by increasing the temperature, returned to the dryer, and added to the superheated steam (see, for example, Patent Document 1).

JP-A-63-231111

In the conventional drying system, the waste is continuously dried in the dryer, and the steam generated by heating the waste is used in addition to the steam for heating the waste to improve the drying efficiency. ing. Moreover, the performance of the drying process in a dryer is improved by providing a preheater and heating waste beforehand. However, it is necessary to continuously heat both the preheater and the dryer. In addition, since steam for heating is stably supplied in the dryer, even if unnecessary excess steam may be generated due to the dry state of the waste, it could not be used efficiently. .
When drying by batch processing, the inside of the dryer is heated to dry the material to be dried, and the material to be dried is discharged from the dryer after the drying is completed. In the drying in the batch processing, the inside of the dryer can be efficiently heated, but usually, the material to be dried is discharged after being cooled to some extent to be discharged from the dryer. A heating medium such as steam is not required from the completion of drying to the completion of discharge. However, since the heating medium is stably supplied, the surplus heating medium generated is not exhausted and used efficiently. There wasn't.

  This invention is made to solve the above problems, and is a batch-type drying process in which a predetermined amount of material to be dried is dried in a dryer and discharged after completion of drying. It is an object of the present invention to provide a drying system with good drying efficiency that can efficiently use surplus heating medium that is generated.

  The drying system according to the present invention includes means for supplying a heating medium, a dryer for drying the material to be dried by the supplied heating medium, and carrying a predetermined amount of the material to be dried into the dryer for drying. Conveying means for carrying out the material to be dried after completion from the dryer. A pre-drying chamber for pre-drying the material to be dried in the dryer, and switching means for switching a supply destination of the supplied heating medium between the pre-drying chamber and the dryer; And a drying completion detecting means for detecting completion of drying of the material to be dried in the dryer. When the drying completion is detected by the drying completion detecting means, the heating medium supplied to the dryer is switched to the preliminary drying chamber by the switching means, and the material to be dried is transferred by the conveying means. After carrying out from the dryer, switching to the dryer again, the material to be dried is preliminarily dried in the predrying chamber between the completion of drying and the completion of the carrying out. It is.

  According to the drying system of the present invention, a preliminary drying chamber is provided so that the heating medium supplied to the dryer is supplied to the preliminary drying chamber while the material to be dried in the dryer is completely dried to unloaded. Since switching is performed, the excess heating medium generated after the drying is completed can be efficiently used for the next drying, and the drying efficiency is improved. Further, since the drying process is performed after the preliminary drying, the drying process time can be shortened and the operation efficiency of the system is improved.

Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below.
FIG. 1 is a diagram schematically showing the structure of a drying system according to Embodiment 1 of the present invention. As shown in the figure, this drying system includes a raw material tank 2 for storing a material to be dried (hereinafter referred to as a raw material) such as sludge to be dried, a rotary valve 3 for cutting out the raw material stored in the raw material tank 2, and a reserve of the raw material. A predrying chamber 1 for drying and stirring, a drier 5 for drying the raw material after the predrying, a steam generation source 7 for supplying steam as a heating medium used in the drying and predrying (hereinafter referred to as heat source 7) And a temperature sensor 11 that detects the temperature of the gas exhausted from the dryer 5 and a control device 15 that controls the flow of steam.

  Further, 4 is a conveyor for conveying the raw material cut out from the rotary valve 3 to the preliminary drying chamber 1, 6 and 12 are screw conveyors as conveying means, and 6 is for conveying the raw material subjected to the preliminary drying treatment to the dryer 5, Unloads the dried raw material (dried product) from the dryer 5. Numerals 8 to 10 are valves made up of solenoid valves that are provided in the pipe 14 for the circulation of steam and controlled by a control signal from the control device 15, and 8 and 10 are dryers for supplying steam from the heat source 7. 5 and the preliminary drying chamber 1 constitute switching means, and 9 constitutes a means for adjusting the flow of steam from the dryer 5 to the preliminary drying chamber 1. Reference numeral 13 denotes a tank for temporarily accumulating dried products carried out from the dryer 5 by the screw conveyor 12. Thus, a drying system is comprised by each part of 1-14 mentioned above.

  In the preliminary drying chamber 1 and the dryer 5, the carried raw material is heated in a non-contact manner with the steam by a method such as circulating steam around it and dried while stirring. During the preliminary drying process and the drying process Gases such as evaporated water generated from the raw material are exhausted by heating the raw material. The temperature of the gas exhausted from the dryer 5 is detected by the temperature sensor 11, and the controller 15 detects that the raw material has been dried in the dryer 5 based on the exhaust temperature detected by the temperature sensor 11. .

FIG. 2 shows the change of the drying evaporative exhaust temperature due to the exhaust gas from the dryer 5 as the drying time elapses.
The exhaust temperature from the dryer 5 increases with the increase in the amount of exhaust gas from the start of the drying process, continues the temperature T1 in the dry season for a predetermined period (H1 to H2), decreases with the decrease in the amount of exhaust gas, and completes drying. However, the exhaust temperature T2 for detecting the completion of drying is determined in advance by data such as experiments.
Steam necessary for the drying process is stably supplied from the heat source 7, and the valve 8 is opened and the valve 10 is closed by the controller 15 so that the steam is normally supplied to the dryer 5. When the control device 15 detects that the exhaust temperature once increased has become T2 or less due to the decrease and detects the completion of drying in the dryer 5, the control device 15 switches the valve 8 to the closed state and the valve 10 to the open state at the time H3. Then, the steam from the heat source 7 is switched to the preliminary drying chamber 1 and supplied. The preliminary drying chamber 1 is loaded with raw materials for the next drying process, and the preliminary drying process is performed with the supplied steam. At this time, no steam is supplied to the dryer 5, and as shown in the exhaust temperature in FIG. 2, the dried product after drying is cooled, and when the temperature reaches the dischargeable temperature T <b> 3 from the dryer 5, the dried product is dried. Unload from the container 5 and complete unloading at time H5. When the dried product is carried out from the dryer 5, the next drying process becomes possible. Therefore, the control device 15 opens the valve 8 and switches the valve 10 to the closed state so that steam is supplied to the dryer 5. At the same time, the raw material in the preliminary drying chamber 1 is conveyed to the dryer 5.
As described above, the period 24 in which the steam is supplied to the dryer 5 and the drying process (to H3) and the period 25 in which the cooling (H3 to H4) and the unloading (H4 to H5) are performed are repeated. Steam is supplied to the preliminary drying chamber 1 to perform a preliminary drying process.

Next, details of the operation of this drying system will be described below based on the flowchart of FIG.
At the start of operation, the raw material to be dried accumulated in the raw material tank 2 is cut out for one batch for the initial drying process by the rotary valve 3, and supplied to the preliminary drying chamber 1 by the conveyor 4 (S1). Next, it is determined whether or not the raw material can be charged into the dryer 5. This determination is made by detecting the free state of the dryer 5 from the load fluctuation of the stirring power attached to the dryer 5 and the load fluctuation of the screw conveyor 12 for carrying out the dried product from the dryer 5. (S2).
When it is determined in step S2 that the raw material can be charged into the dryer 5, the raw material is carried into the dryer 5 by the screw conveyor 6 from the preliminary drying chamber 1 (S3), and the valve 8 is opened by the control device 15. The valve 10 is controlled to be closed, steam from the heat source 7 is supplied to the dryer 5 to heat the inside of the dryer 5, supply to the preliminary drying chamber 1 is stopped, and heating in the preliminary drying chamber 1 is stopped. To do. In addition, at the time of the first drying process, since the preliminary drying chamber 1 is not heated, the heating stop state is continued (S4).

Thereafter, the drying process of the raw material is performed in the dryer 5, while the raw material to be processed next is cut out from the raw material tank 2 by the rotary valve 3 and supplied to the preliminary drying chamber 1 by the conveyor 4 (S 5). The completion of drying in the dryer 5 can be detected based on the exhaust temperature as described above, and when the control device 15 detects the completion of drying (S6), the valve 8 is closed and the valve 10 is switched to open. 5 is stopped and switched to heating in the preliminary drying chamber 1 (S7).
Thereafter, the raw material is preliminarily dried in the predrying chamber 1, while only the stirring operation is continued in the dryer 5 to cool the dried product (S8). Next, after predetermined cooling, the dried product is carried out from the dryer 5 to the tank 13 by the screw conveyor 12. The carry-out timing may be determined based on the detected exhaust temperature as described above, or a cooling period may be set in advance based on experimental data or the like (S9). Subsequently, it is determined by the same method as in step S2 whether or not the material can be fed out from the dryer 5 (S10), and it is determined in step S9 that the material can be charged into the dryer 5. Then, it is determined whether the operation is finished or continued (S11). When the operation is continued, the process returns to step S3. In the case of ending, the valve 10 is controlled to be closed by the control device 15, the supply of steam to the preliminary drying chamber 1 is stopped and the heating in the preliminary drying chamber 1 is stopped (S 12), and the operation is ended.

  Note that the end of the operation in step 11 is detected at the time immediately before the end, and steps S5 and S7 are omitted in the last drying process from step S3, that is, the preliminary drying process without supplying the raw material to the preliminary drying chamber. May be omitted. In that case, there is no heating stop process in the preliminary drying chamber 1 in step S12.

  In this embodiment, as described above, the completion of drying is detected and the supply of steam to the dryer 5 is stopped. Instead, the supply of steam to the preliminary drying chamber 1 is performed, and the preliminary drying of the raw material to be dried next is performed. I do. Thus, the excess steam during cooling and unloading of the dried product can be effectively used for preliminary drying in the next drying, and the supplied steam can be effectively used without waste. For this reason, the drying efficiency is improved, and since the drying process is performed after the preliminary drying, the drying process time can be shortened and the operation efficiency of the system is also improved.

Further, since the exhaust temperature from the dryer 5 is detected and the completion of drying in the dryer 5 is detected, the completion of drying can be detected easily and reliably, and the supply of steam is transferred from the dryer to the preliminary drying chamber. Can be switched.
Furthermore, since the raw material is stirred in the preliminary drying chamber 1, the efficiency of preliminary drying is improved and the introduction into the drying process in the dryer 5 can be performed smoothly.

Embodiment 2. FIG.
In the first embodiment, the valve 9 is not controlled. However, when steam is circulated from the dryer 5 to the preliminary drying chamber 1, the control is performed as follows. When the controller 15 detects the completion of drying, the valve 9 is switched from closed to open, and steam is circulated from the dryer 5 to the preliminary drying chamber 1. When the transported product is completely removed from the dryer 5, the valve 9 is opened. Switch to closed to shut off steam flow.
Thereby, the cooling efficiency after completion of drying in the dryer 5 is improved, and the efficient use of surplus steam can be promoted.

  In the first and second embodiments, steam is used as the heating medium. However, the present invention is not limited to this, and other high-temperature gas or liquid such as high-temperature water may be used.

Embodiment 3 FIG.
In the first embodiment, the temperature sensor 11 that detects the temperature of the gas exhausted from the dryer 5 is provided, and the completion of drying in the dryer 5 is detected based on the detected exhaust temperature. Then, the weight of the raw material (dried product) is detected to detect the completion of drying.
As shown in FIG. 4, the weight of the dryer 5 is detected by the weight sensor 62, and the weight of the raw material is obtained by subtracting the known weight unique to the dryer by the control device 15. Since the moisture content of the dried raw material (dried product) is substantially constant, the completion of drying can be detected easily and reliably from the weight of the raw material.
As described above, the control device 15 detects the weight of the raw material based on the weight from the weight sensor 62 and detects the completion of drying. Then, the supply of steam to the dryer 5 is stopped, and instead, the supply of steam to the preliminary drying chamber 1 is performed, and the raw material to be dried next is subjected to preliminary drying.
For this reason, as in the first embodiment, the excess steam during the cooling and unloading of the dried product can be effectively used for preliminary drying in the next drying, and the supplied steam can be effectively used without waste. In addition, a dry product with good uniformity in moisture content of the dry product and a high quality can be obtained.

  In addition, since it is equipped with a means to detect the weight of the raw material, the weight can be constantly monitored, and not only when the drying is completed, but also the dry state of the raw material (such as water content) can be monitored, and the drying process Reliability is improved.

  As shown in FIG. 4, the preliminary drying chamber 1 is also provided with a weight sensor 61 to detect and monitor the weight of the raw material, so that the drying is continuously performed from the start of the preliminary drying process to the completion of the drying process. The condition can be monitored, and the reliability of the entire drying process is further increased.

Embodiment 4 FIG.
In the first to third embodiments, the gas such as evaporated moisture generated by heating from the raw material is exhausted from the system after being exhausted from the dryer 5 and the preliminary drying chamber 1. Then, the exhaust gas is also used for heating.
As shown in FIG. 5, the raw material tank 2 a that stores the raw material is provided with a heat retaining function, and exhaust gas from the dryer 5 and the preliminary drying chamber 1 is supplied to the raw material tank via the gas pipe 47. In addition, valves 45 and 46 made of electromagnetic valves are provided, and the control device 15 controls the flow. Control is performed so that the valve 46 is opened during the drying process by heating of the dryer 5 and the valve 45 is opened during the preliminary drying process by heating of the preliminary drying chamber 1.

In this embodiment, since the exhaust gas generated from the raw material is supplied to the raw material tank 2a, the thermal energy of the exhaust gas can be used effectively, and the drying efficiency is further improved.
In particular, the exhaust gas from the dryer 5 has a large amount of heat energy because the temperature rises to about 70 to 100 ° C., for example, and a highly efficient drying system can be obtained by utilizing it without waste.
The exhaust gas from either the dryer 5 or the preliminary drying chamber 1 may be used.

It is a figure which shows the structure of the drying system by Embodiment 1 of this invention. It is a figure which shows the exhaust-gas temperature change from the dryer by Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the drying system by Embodiment 1 of this invention. It is a figure which shows the structure of the drying system by Embodiment 3 of this invention. It is a figure which shows the structure of the drying system by Embodiment 4 of this invention.

Explanation of symbols

1 Pre-drying chamber, 2,2a Raw material tank, 5 dryer,
7 Heat source as heating medium supply means, 6, 12 Conveyor as conveying means,
8, 10 Valve as switching means, 9 Valve as adjustment means, 11 Temperature sensor, 47 Heating medium (steam) piping, 45, 46 valve, 47 Gas piping,
61, 62 Weight sensor.

Claims (8)

Means for supplying a heating medium, a dryer for drying the material to be dried with the supplied heating medium, and carrying a predetermined amount of the material to be dried into the dryer, and the material to be dried after drying is completed. In a drying system comprising a conveying means for carrying out from the dryer, a preliminary drying chamber for pre-drying the material to be dried in the dryer, and a supply destination of the supplied heating medium. Switching means for switching between the preliminary drying chamber and the dryer, and a drying completion detecting means for detecting completion of drying of the material to be dried in the dryer, the drying completion detecting means detecting the completion of drying. Then, the heating medium supplied to the dryer is switched to the preliminary drying chamber by the switching means, and the material to be dried is transported from the dryer by the transport means, and then switched to the dryer again. Instead, the drying system, characterized in that the the dried material is between the completion of drying to the carry-out completion, it causes the object to be dried material then dried is predried in the predrying chamber. The drying process in the dryer is to heat and dry the material to be dried without contact with the heating medium, and exhaust means for exhausting the gas generated from the material to be dried from the dryer; An exhaust temperature detector for detecting the temperature of the exhaust gas, and the drying completion detecting means determines the completion of drying of the material to be dried in the dryer based on the temperature detected by the exhaust temperature detector. The drying system according to claim 1, wherein the drying system is detected. A weight detector for detecting the weight of the material to be dried in the dryer is provided, and the drying completion detecting means detects the completion of drying of the material to be dried based on the weight detected by the weight detector. The drying system according to claim 1. 4. The drying system according to claim 3, wherein the drying completion detecting means monitors the drying state of the material to be dried in the dryer based on the weight detected by the weight detector. A second weight detector for detecting a weight of the material to be dried in the preliminary drying chamber; and means for monitoring a dry state of the material to be dried in the preliminary drying chamber based on the detected weight. The drying system according to claim 4. The drying system according to any one of claims 1 to 5, wherein the preliminary drying chamber performs a process of stirring the material to be dried in a room. Means for circulating the heating medium from the dryer to the preliminary drying chamber, and means for adjusting the circulation, and when the drying completion is detected by the drying completion detecting means, the heating medium is removed from the dryer. The drying system according to any one of claims 1 to 6, wherein the circulation is interrupted after the material is circulated from the dryer to the preliminary drying chamber and the material to be dried is carried out of the dryer by the conveying means. . A tank for storing the material to be dried is provided in the front stage of the preliminary drying chamber, and a gas generated from the material to be dried by one or both of a drying process in the dryer and a preliminary drying process in the preliminary drying chamber is provided. The drying system according to any one of claims 1 to 7, further comprising means for supplying the tank.

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