JPH0576694A - Solvent recovery tytpe drier - Google Patents

Abstract

PURPOSE:To continue safely surely a drying process and improve efficiency of the whole drying process even if the continuation of recovering and drying running gets difficult. CONSTITUTION:A draft path 2 including a rotary drum 1 on the way is enclosed to adjust the condition of heating a heater 4 on the basis of the measuring result of a drum incoming side thermometer 11 and introduce hot air controlled to a predetermined temperature into the rotary drum 1 while the recovering and drying running is carried out to circulate hot air heated by the heater 4 and recover gasified solvent condensed by a cooler 6. At the same time, the temperature measuring result of a drum outcoming side thermometer 12 is utilized to judge the properness of temperature control. If the temperature control is judged improper, an intake valve 8 and exhaust valve 9 are optned to open a air path 2 so that the running is shifted to the exhaust drying running.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solvent recovery type drier configured to be capable of a recovery / drying operation for recovering a solvent contained in a material to be dried.

[0002]

2. Description of the Related Art A conventional dryer for drying a material to be dried such as clothes washed with a petroleum-based solvent is, for example, disclosed in Japanese Patent Laid-Open No. 3-9798. It is provided with a cylindrical storage tank for storing the dehydrated material to be dried and rotating around a horizontal axis, and an air passage including the storage tank in the middle thereof, and upstream of the storage tank inside the air passage. On the side, a heater that performs heating operation by supplying a blower fan and steam,
Similarly, coolers that perform cooling operation by supplying cooling water are respectively arranged on the downstream side, and further, the air passages are opened and closed to the outside air between the upstream side of the blower fan and between the storage tank and the cooler. The switch valve is provided.

The dryer is operated so that the air passage is made into a circulating air passage closed to the outside air by closing the switching valve, and a blower fan, a heater and a cooler are operated in this state to carry out recovery drying. Operation and opening of the switching valve to make the air passage an open air passage, and the hot air exhaust drying operation to operate the air blower fan and the heater in this state, and cold air exhaust operation to operate only the air blower fan in the open air passage state The drying operation (cool down) is performed in this order in a procedure of continuing for a predetermined time.

In the recovery / drying operation, the circulating air blown by the blower fan is heated by the heater and introduced into the storage tank, and the solvent contained in the material to be dried inside the storage tank is evaporated and carried out. , And to be condensed and recovered by contact with the cooler. Therefore, in order to improve the efficiency of this operation, it is necessary to bring the temperature of the hot air inside the storage tank as close as possible to the ignition temperature of the solvent, and to detect the temperature of the hot air at the inlet and outlet sides of the storage tank. In order to match the detection result with the target temperature set near the ignition temperature, for example, temperature control is performed in a procedure of cutting off the steam supplied to the heater.

[0005]

However, when a petroleum solvent is used to wash the material to be dried, the temperature control in the recovery and drying operation is about 41 ° C. on the outlet side of the storage tank and 44 ° C. on the inlet side. While the target temperature is about (outside temperature + 3 ° C), the ambient temperature when using the dryer is often close to this target temperature. In such a case, delicate temperature control in a narrow range is performed. Therefore, there is a problem that the internal temperature of the storage tank tends to become unstable.

In such a case, conventionally,
In order to prevent damage to the material to be dried due to ignition, safety measures have been taken to automatically stop the operation of the dryer itself, and each time this is stopped, a new operation is required to start the operation,
This is a factor that causes a decrease in the efficiency of the entire drying process.

The present invention has been made in view of such circumstances, and even when the recovery / drying operation becomes difficult to continue, the drying process can be safely and reliably continued, and the efficiency of the drying process can be improved. It is an object to provide a solvent recovery type dryer.

[0008]

A solvent recovery type dryer according to the present invention seals an air passage including a storage tank for a material to be dried which has been washed with a solvent in the middle thereof, and uses a heater upstream of the storage tank to perform the above-mentioned operation. A hot air whose temperature is controlled is circulated in the vicinity of the flash temperature of the solvent, and the vaporized solvent contained in the circulated air is collected and condensed by a cooler on the downstream side of the storage tank, and the air passage is opened. , An exhaust air drying operation in which outside air is sucked in on the upstream side of the heater, introduced into the storage tank in a heated or non-heated state, and discharged on the upstream side of the cooler, in this order, each continues for a predetermined time. In the solvent recovery type dryer, means for determining suitability of temperature control during the recovery / drying operation, and when the determination is inappropriate by the means, suspends the recovery / drying operation and shifts to the exhaust / drying operation. Equipped with means And wherein the Rukoto.

[0009]

In the present invention, when it is determined that the temperature control becomes unstable due to an increase in the ambient temperature during the recovery / drying operation and the solvent may catch fire, the recovery / drying operation is interrupted and The exhaust drying operation is automatically executed to prevent stagnation of the entire drying process and improve efficiency.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. 1 and 2 are operation explanatory views of the solvent recovery type dryer according to the present invention. As shown in the figure, the solvent recovery type dryer according to the present invention stores a material to be dried C that has been drained after cleaning and has a cylindrical rotary drum (storage tank) 1 that is driven to rotate around a horizontal axis. An air passage 2 including the rotary drum 1 in the middle thereof.

On the upstream side of the rotary drum 1 inside the air passage 2,
The blower fan 3 and the heater 4 are provided downstream with a lint filter 5 and a cooler 6, respectively. Below the cooler 6, a recovery solvent storage tank 7 is detachably mounted. The downstream side of the cooler 6 and the upstream side of the blower fan 3 are in communication with each other. In the middle of this communication part, an intake port A that communicates the inside of the air passage 2 with the outside air can be opened and closed by an intake valve 8. Further, an exhaust port 9 is similarly formed between the lint filter 5 and the cooler 6 by an exhaust valve 9 so as to be openable and closable.

When the intake port A and the exhaust port B are closed by the intake valve 8 and the exhaust valve 9, respectively, the air passage 2 becomes a closed air passage as shown in FIG. 1, and when the blower fan 3 is driven at this time. The air blown by the blower fan 3 is introduced into the rotary drum 1 via the heater 4 on the downstream side thereof and further circulates to the blower fan 3 via the lint filter 5 and the cooler 6, while the intake valve 8 and the exhaust valve 9 are turned on. If opened, the air passage 2
2 is an open air path in which both sides of the cooler 6 are open to the outside air as shown in FIG. 2. At this time, when the blower fan 3 is driven,
Outside air is sucked into the air passage 2 from the intake port A in the open state, introduced into the rotary drum 1 via the heater 4, and then passed through the lint filter 5 to the open state without reaching the arrangement position of the cooler 6. It is discharged from a certain exhaust port B.

Steam for heating is sent to the heater 4 from a steam source (not shown), and when the steam inlet valve 4a and the steam outlet valve 4b both of which are electromagnetic valves are opened,
The ventilation in the air passage 2 is heated by contact with the heater 4 and introduced into the rotary drum 1, while the supply of steam to the heater 4 is stopped when the both valves 4a and 4b are closed. The ventilation in the air passage 2 is introduced into the rotating drum 1 in the unheated state. That is, the temperature of the hot air introduced into the rotary drum 1 can be adjusted by opening / closing the steam inlet valve 4a and the steam outlet valve 4b.

Further, the cooler 6 is provided with a water pipe through which cooling water is constantly passed, and the ventilation inside the air passage 2 in a hermetically sealed state is cooled when passing through the installation position of the cooler 6. It is cooled by heat exchange with water, and at this time, the solvent contained in the ventilation is condensed and dropped into the storage tank 7 to be collected.

On the inlet side and the outlet side of the rotary drum 1, a drum inlet side thermometer 11 and a drum outlet side thermometer 12 for detecting the ventilation temperature at the respective installation positions are fixed, respectively, and a cooler. A cooler outlet side thermometer 13 for detecting the ventilation temperature after cooling by the cooler 6 is fixedly provided on the outlet side of 6. A thermistor is used as each of these thermometers 11, 12, and 13.

FIG. 3 is a block diagram of a control system which controls the operation of the solvent recovery type dryer according to the present invention. In the figure, 10 is a control unit using a microprocessor.
On the input side of the, the respective temperature measurement results by the drum inlet side thermometer 11, the drum outlet side thermometer 12 and the cooler outlet side thermometer 13 described above are given and arranged on the operation panel (not shown). The key switch 14 gives the operation mode designation result.

On the other hand, the output of the control unit 10 is a drum drive motor 1a for driving the rotary drum 1, a fan drive motor 3a for driving the blower fan 3, an intake valve 8 and an exhaust valve 9 for opening and closing the air passage 2, and a heater 4. Steam inlet valve 4a and steam outlet valve to
It is given to the display unit 15 in addition to being given to the display unit 4b, and the current operating state and the like are displayed on the display unit 15.

In the solvent recovery type dryer according to the present invention constructed as described above, the air passage 2 is closed by closing the intake valve 8 and the exhaust valve 9 as in the conventional case, and the blower fan 3,
Recovery drying operation performed by operating both the heater 4 and the cooler 6 and opening of the intake valve 8 and the exhaust valve 9 to make the air passage 2 an open air passage, and operating the blower fan 3 and the heater 4 to perform warm air exhaust Drying operation and cold air exhaust drying operation which is performed by operating only the blower fan 3 in the same manner are possible.

Normally, these are operated in a mode in which each of them is continued for a predetermined time, but the recovery / drying operation is omitted, and the operation mode in which only the exhaust drying operation and the recovery / drying operation and the warm air exhaust drying operation are omitted. However, it is also possible to select an operation mode in which only the cold air exhaust drying operation is performed, and the operator can set a desired operation mode by operating the key switch 14.

FIG. 4 is a flow chart showing the operation contents of the control unit 10. The control unit 10 starts its operation in response to an ON operation of a main switch (not shown), and drives the drum drive motor.
1a and the fan drive motor 3a are issued with an operation command to drive the rotary drum 1 and the blower fan 3, and first, the operation state of the key switch 14 is checked to confirm the set operation mode (steps 1 and 2), According to the set operation mode, recovery drying operation (step 3), warm air exhaust drying operation (step 4) and cold air exhaust drying operation (step 5)
, And perform the respective processing.

First, the operation contents in the exhaust drying operation (steps 4 and 5) will be briefly described. In the warm air exhaust drying operation (step 4), the control unit 10 causes the intake valve 8 and the exhaust valve 9 to operate.
To the steam inlet valve 4a and the steam outlet valve 4b, the heater 4 is heated.

At this time, the outside air sucked from the suction port A by the operation of the blower fan 3 becomes warm air due to the contact with the heater 4 and passes through the inside of the rotating rotary drum 1 to dust the lint filter 5. After being captured, it is discharged to the outside air through the open exhaust port B. At this time, the material C to be dried inside the rotary drum 1 is quickly dried by being deprived of the residual liquid content due to contact with the warm air, but this liquid is discharged to the outside air through the exhaust port B, so this temperature The operation start mode from the wind exhaust drying operation is performed only when the material to be dried C inside the rotary drum 1 is in a state of being dried to some extent.

This warm air exhaust drying operation is completed after waiting for a preset predetermined time (step 6), and when the operation start from the cold air exhaust drying operation is selected in step 2, the step 5 Then, the cold air exhaust drying operation is performed. In this cold air exhaust drying operation, the control unit 10 issues an opening command to the intake valve 8 and the exhaust valve 9, and the air passage 2
As an open air passage and the steam inlet valve 4a and steam outlet valve
A close command is issued to 4b to put the heater 4 into a non-heated state.

At this time, the outside air sucked from the suction port A by the operation of the blower fan 3 is introduced into the rotary drum 1 while maintaining the temperature as it is, and the lint filter 5 and the exhaust port B are discharged.
Is discharged to the outside air. At this time, the material to be dried C inside the rotary drum 1 comes into contact with the cold air, a certain degree of drying effect is obtained, and the material to be dried C that has become high temperature due to the hot air exhaust drying operation is cooled. Promoted,
Safe removal from the rotary drum 1 is possible. Similar to the warm air exhaust drying operation, the cold air exhaust drying operation waits for the elapse of a preset predetermined time (step 7) and ends, and the control unit 10 ends a series of operation operations.

On the other hand, in the recovery / drying operation (step 3), the control section 10 issues a close command to the intake valve 8 and the exhaust valve 9 to keep the air passage 2 in a hermetically closed state and operate the heater 4. As a result, the circulating air generated by the blower fan 3 follows the route of returning to the blower fan 3 through the heater 4, the rotary drum 1, the lint filter 5, and the cooler 6 in this order.
Then, at this time, the solvent remaining on the material to be dried C in the rotary drum 1 comes into contact with the hot air heated by the contact with the heater 4, is evaporated and evaporated in the hot air, and is carried out by the lint filter 5. After the dust is removed, the dust comes into contact with the cooler 6 to condense and is dropped into the storage tank 7 to be collected.

The recovery and drying operation as described above is performed by the rotating drum 1.
It is necessary to appropriately maintain the warm air temperature on the inlet side and the outlet side of the control unit 10 after the transition to Step 3.
Takes in the inlet temperature t ₁ of the rotary drum 1 by the input from the drum inlet thermometer 11 (step 8), compares it with a predetermined target temperature T ₁ (step 9), and t ₁ is T ₁ If the temperature exceeds the limit, a close command is issued to the steam inlet valve 4a and the steam outlet valve 4b to stop the steam supply to the heater 4 (step 10), and the inlet side temperature t ₁ of the rotating drum ₁ is lowered. Plan
Next, it is determined whether or not the preset duration of the recovery / drying operation has elapsed (step 11). If the duration is within the duration, the process returns to step 8 and the above-mentioned operation is repeated, and if the duration is exceeded. In step S4, the warm air exhaust drying operation described above is performed.

On the other hand, as a result of the comparison in step 9, when it is determined that t ₁ is equal to or lower than the target temperature T ₁ , the control unit 10 then inputs the output from the drum output side thermometer 12 to output the rotary drum 1. side temperature t ₂ uptake (step 12), which was compared predetermined target temperature T ₂ (step 13), t ₂ is T
If it exceeds ₂ , this comparison is continued for a predetermined time (step 14). Then, during this continuation, the target temperature T ₂
When the excess is solved, and when it is determined in step 13 that t ₂ is equal to or less than T ₂ , an opening command is issued to the steam inlet valve 4a and the steam outlet valve 4b (step 15),
The steam supply to the heater 4 is restarted to raise the inlet side temperature t ₁ of the rotating drum 1, and then the process proceeds to step 11 to continue the recovery / drying operation or shift to the hot air exhaust drying operation.

On the other hand, if the excess of the target temperature T ₂ is not resolved during the elapse of the predetermined time in step 14, the recovery drying operation is interrupted and the process proceeds to step 4 to shift to the hot air exhaust drying operation.

In each of the operations in step 10 and step 15, the supply of steam is cut off to adjust the degree of heating at the position where the heater 4 is disposed, and the inlet side temperature t ₁ of the rotary drum 1 is changed to the target temperature T. _This is performed so as to coincide with 1. In step 14, it is determined whether or not the temperature inside the rotary drum 1 can be properly maintained by cutting off the supply steam to the heater 4.

That is, the target temperature T ₂ on the output side of the rotary drum 1
Is set on the basis of the flash temperature of the solvent used for cleaning the material to be dried C, and the target temperature T ₁ on the inlet side is predicted by heat exchange with the material to be dried C in the rotary drum 1. The temperature is set slightly higher than T ₂ in consideration of the temperature drop. For example, when using a petroleum-based solvent, T ₂ is
Around 41 ° C, T ₁ is set around 44 ° C (= T ₂ + 3 ° C).

Therefore, when the heat exchange is normally performed in the rotary drum 1, when the determination in step 9 is NO, that is, when t ₁ ≤T ₁ , it is normal to execute step 13
The result of the determination in NO is also NO, that is, t ₂ ≦ T _2, and the result of this determination is YES, and the fact that this state continues for a predetermined time means that the ambient temperature rises, This indicates that the recovery / drying operation cannot be continued due to an abnormal temperature rise. In the solvent recovery type dryer according to the present invention, in such a case, the operation is continued by shifting to a safer hot air exhaust drying operation, and an unnecessary operation stop is performed in the middle of the drying process. Safe, surely continuous drying process
The efficiency of the drying process is realized.

The comparison duration in step 14 is about 3 minutes, and the temperature measurement result of the cooler outlet side thermometer 13 is used for detecting the abnormality of the cooler 6 during the recovery / drying operation. Further, in the present embodiment, the inlet side temperature t ₁ of the rotary drum ₁ was used for the temperature control of the recovery / drying operation, and the outlet side temperature t ₂ was used for determining the suitability of this temperature control. It is also possible to use the outlet temperature t ₂ and the inlet temperature t ₁ for this suitability determination.

[0033]

As described in detail above, in the solvent recovery type dryer according to the present invention, the suitability of temperature control is judged during the recovery / drying operation, and the temperature control becomes unstable due to, for example, an increase in ambient temperature. If an unsuitable judgment is made, the recovery / drying operation, which may cause the solvent to ignite, is interrupted, and a safer exhaust drying operation is performed. The present invention has excellent effects such that the drying process can be continued and the efficiency of the entire drying process can be improved.

[Brief description of drawings]

FIG. 1 is an operation explanatory view of a solvent recovery type dryer according to the present invention.

FIG. 2 is an operation explanatory view of the solvent recovery type dryer according to the present invention.

FIG. 3 is a block diagram of a control system of the solvent recovery dryer according to the present invention.

FIG. 4 is a flowchart showing the operation contents of the solvent recovery type dryer according to the present invention.

[Explanation of symbols]

 1 rotating drum 2 air passage 4 heater 6 cooler 8 intake valve 9 exhaust valve 10 controller 11 drum inlet side thermometer 12 drum outlet side thermometer

Claims (1)

[Claims] 1. An air passage including a storage tank for a material to be dried that has been washed with a solvent is closed, and a heater upstream of the storage tank circulates a temperature-controlled warm air near the flash temperature of the solvent. Then, the vaporizing solvent contained in the circulating air is collected and dried by condensing the vaporized solvent by the cooler on the downstream side of the storage tank, the air passage is opened, and the outside air is sucked in on the upstream side of the heater for heating or non-heating. A temperature control during the recovery / drying operation in a solvent recovery type dryer that is introduced into the storage tank in a heated state and discharges at the upstream side of the cooler in this order for a predetermined time, respectively. Of the solvent recovery type dryer, and means for interrupting the recovery / drying operation and shifting to the exhaust / drying operation when the suitability is determined by the means. ..