JP2006071240A - Circulation drying device operating method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circulation drying device operating method for hardly causing a trouble in automatic operation during a time from starting operation to starting the spray of a dried object. <P>SOLUTION: The method of operating a circulation drying device 10 uses gas heated by a heater 12 while being circulated between the heater 12 and a dryer 14 for drying the dried object sprayed into the dryer 14. Herein, operation during a time from starting the operation of the circulation drying device 10 to starting the spray of the dried object is divided into a plurality of steps consisting of one operation or a plurality of related operations. In each step, one of a valve, a thermometer, a pressure gauge, a fan and a pump provided in the circulation drying device 10, whose condition should be checked, is previously listed. In each step, the listed one is automatically checked to be in a set condition or not. Only when the listed one is in the set condition, the step proceeds to the next. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method of operating a circulation type drying apparatus that dries an object to be dried sprayed into a dryer by gas heated by the heater while circulating the gas between the heater and the dryer.

Conventionally, an open cycle method and a closed cycle method (circulation method) are known as a method of spraying an object to be dried such as a polymer latex and drying it with a heated gas.
The open cycle method is a method in which a gas used for drying an object to be dried is released into the atmosphere as an exhaust gas. Therefore, in the open cycle system, a high temperature gas is released into the atmosphere, so that energy loss is large.

  On the other hand, a closed cycle method, that is, a drying method using a circulation type drying apparatus, is a drying method that is advantageous in terms of energy compared to the open cycle method because most of the exhaust gas is reused as a drying gas. However, although the circulation drying device is provided with means for exhausting excess gas little by little to adjust the pressure in the device, most of the gas is confined in the device. When the temperature of the water changes rapidly, the pressure also changes rapidly. Therefore, it is difficult to operate in a state where the gas pressure is stable as compared with an open cycle system.

  In the drying method using a circulation type drying device, once drying of an object to be dried is started, the pressure and temperature in the circulation type drying device are stable unless the amount or concentration of the object to be dried is greatly changed. The operation can be performed while the pressure is automatically controlled by exhausting excess gas little by little so that the gas pressure is in a predetermined range. However, during the period from the start of operation to the start of spraying of the drying object, it is necessary to raise the temperature in the circulation drying device from room temperature to the temperature necessary for drying the drying object. The pressure is likely to be unstable (unsteady state).

  In such an unsteady state, when the temperature rises instantaneously for some reason, automatic control of the pressure cannot follow the pressure rise, and troubles such as an emergency stop of the circulation type drying apparatus are likely to occur. Therefore, during the period from the start of operation to the start of spraying of the drying object, a plurality of workers constantly monitor the circulation type drying apparatus and perform operations from the start of operation to the start of spraying of the drying object while paying close attention. It is necessary to perform these operations automatically.

In addition, Patent Document 1 proposes an open-cycle drying apparatus that controls operation in a fully automatic manner. However, since it is an open cycle system, strict pressure control as required for the closed cycle system is not taken into consideration, and further, no mention is made of automatic operation at the start of operation of the drying apparatus of the closed cycle system. .
Japanese Utility Model Publication 1-139801

  Therefore, the object of the present invention is to make it difficult for abnormalities to occur even if the operation from the start of operation to the start of spraying of the drying object is performed automatically, and even if an abnormality occurs, the cause can be easily identified, Another object of the present invention is to provide a method of operating a circulation type drying apparatus that does not lead to any trouble.

  That is, the operation method of the circulation type drying apparatus of the present invention dries the drying object sprayed in the dryer with the gas heated by the heater while circulating the gas between the heater and the dryer. A method for operating a circulation drying apparatus, wherein all operations from the operation start of the circulation drying apparatus to the start of spraying of an object to be dried are preliminarily performed in a plurality of steps including one operation or a plurality of related operations. For each step, list in advance the valves, thermometers, pressure gauges, fans, and pumps that should be checked for their status in the circulation dryer; list for each step Automatically check whether the listed items are in the preset state; only when the listed ones are in the set state, it automatically goes to the next step Characterized by transition.

Further, in the operation method of the circulation type drying apparatus of the present invention, excess gas is exhausted so that the gas pressure is within a predetermined range between the start of operation of the circulation type drying apparatus and the start of spraying of the drying object. A plurality of temperature raising steps for gradually raising the gas to a predetermined temperature by a heater while controlling the pressure; checking the gas pressure at each temperature raising step; When it falls within the range, it is desirable to shift to the next temperature raising step.
In the operation method of the circulation type drying apparatus of the present invention, it is desirable to control the exhaust fan that sucks the gas in the dryer so that the pressure in the dryer is within a predetermined range.

  According to the operation method of the circulation type drying apparatus of the present invention, even if the operation from the start of operation to the start of spraying of the object to be dried is automatically performed, it is difficult for the abnormality to occur. Is easy and does not lead to serious troubles.

Hereinafter, the present invention will be described in detail.
<Circulating dryer>
FIG. 1 is a schematic configuration diagram showing an example of a circulation type drying apparatus in the present invention. The circulation drying apparatus 10 includes a heater 12 that heats a gas, a dryer 14 that dries latex (an object to be dried) with the gas heated by the heater 12, and a gas discharge port 16 at the bottom of the dryer 14. For collecting and separating powder contained in the gas discharged from the gas, and for cooling the gas from which the powder has been separated by the collector 18, for condensing and separating moisture in the gas A cooling tower 20, a recooling tower 22 that cools a cooling medium (water) for cooling the cooling water for the gas cooling tower 20, a cooling water for the gas cooling tower 20, and a refrigerant body from the recooling tower 22 Included in the heat exchanger 24 for cooling water for exchanging heat, the preheater 26 for preheating the gas, and part of the gas extracted from the preheater 26 on the way back to the heater 12 And the fuel discharged from the hot stove 28. A heat exchanger 30 that exchanges heat between the gas and a gas that flows through a heat exchange channel, which will be described later, and these heater 12, dryer 14, collector 18, gas cooling tower 20, recooling tower 22, cooling A flow path connected to the water heat exchanger 24, the preheater 26, the hot stove 28, and the heat exchanger 30, a valve, a thermometer, a pressure gauge, a fan, and a pump provided in the flow path, and a dryer 14 and a controller 34 electrically connected to a valve, a thermometer, a pressure gauge, a fan, and a pump in the circulation type drying apparatus 10. Is.

  Here, the flow path supplies the gas heated by the heater 12 to the dryer 14 and the gas discharged from the gas outlet 16 of the dryer 14 to the collector 18. The exhaust gas flow path 38, the filtration gas flow path 40 for supplying the gas from which the powder has been separated by the collector 18 to the gas cooling tower 20, and the cooling for supplying the gas cooled by the gas cooling tower 20 to the preheater 26 A gas passage 42, a preheating gas passage 44 for returning the gas heated by the preheater 26 to the heater 12, a branch passage 46 for extracting a part of the gas from the preheating gas passage 44 and supplying it to the hot stove 28, A combustion gas channel 48 that returns the combustion gas discharged from the hot stove 28 to the gas in the heated gas channel 36, branches off from the combustion gas channel 48, and a part of the combustion gas cooled by the heat exchanger 30 is sent to the outside. From the combustion gas exhaust passage 50 and the preheating gas passage 44 to be exhausted A part of the gas is extracted from the heat exchange channel 52 and the preheated gas channel 44 that merges with the heated gas channel 36 through the heat exchanger 30, and is added to the heating unit provided in the dryer 14. An assist air passage 54 for supplying assist air to a pressurized two-fluid spray nozzle (not shown), a cooling gas exhaust passage 56 for exhausting a gas branched from the cooling gas passage 42, and a heating gas passage 36 are branched and heated. The circulation open flow path 58 for exhausting the gas circulating between the dryer 12 and the dryer 14, the nitrogen gas supply pipe 60 for supplying nitrogen gas to the collector 18, and the LPG (liquefaction) as fuel for the hot stove 28 (Oil gas) LPG supply pipe 62 for supplying gas, air supply pipe 64 for supplying air to the hot stove 28, latex supply pipe 66 for supplying latex to the pressurized two-fluid spray nozzle (not shown) of the dryer 14, latex Supply pipe 6, a water supply pipe 68, a cooling water circulation passage 70 for circulating cooling water between the gas cooling tower 20 and the cooling water heat exchanger 24, a recooling tower 22 and a cooling water heat exchanger 24. These are a refrigerant circulation path 72 for circulating the refrigerant between them and a heating steam supply pipe 74 for supplying heating steam to the heater 12.

  The heated gas passage 36 is provided with a manual circulation gate valve 76, the exhaust gas passage 38 is provided with a manual collector inlet gate valve 78, and the filtered gas passage 40 is manually collected. A branch outlet valve 80 is provided in the branch passage 46, a combustion gas return valve 84 is provided in the combustion gas passage 48, and a pressure control is provided in the combustion gas exhaust passage 50. A valve 86 is provided, a cooling gas outlet valve 88 is provided in the cooling gas exhaust passage 56, a circulation opening valve 90 is provided in the circulation opening passage 58, and a latex supply valve 92 is provided in the latex supply pipe 66. The water supply pipe 68 is provided with a water supply valve 94, and the heating steam supply pipe 74 is provided with a heating steam control valve 96.

  The preheating gas channel 44 is provided with a blower fan 98, the filtered gas channel 40 is provided with an exhaust fan 100, the branch channel 46 is provided with a branch fan 102, and the heat exchange channel 52 is provided with Is provided with a cooling fan 104, a roots blower 106 is provided in the assist air flow path 54, an air blowing fan 108 is provided in the air supply pipe 64, and a liquid feed pump 110 is provided in the latex supply pipe 66. A cooling water circulation pump 112 is provided in the water circulation passage 70, a refrigerant circulation pump 114 is provided in the refrigerant circulation passage 72, and a recooling tower fan 116 is provided in the recooling tower 22.

  Further, the heating gas passage 36 is provided with a dryer inlet thermometer 118, the exhaust gas passage 38 is provided with a dryer outlet thermometer 120, and the cooling tower outlet pressure gauge 122 of the cooling gas passage 42 is provided. The hot gas furnace outlet thermometer 136 is provided at the outlet side of the hot gas furnace 28 of the combustion gas flow path 48, the air flow meter 138 is provided at the preheating gas flow path 44, and the cooling water thermometer is provided at the cooling water circulation flow path 70. 140 is provided. Here, the dryer inlet thermometer 118 is electrically connected directly to the heating steam control valve 96 so that the flow rate of the heating steam can be controlled according to the inlet temperature of the dryer 14 by an inverter. The dryer pressure gauge 32 is electrically connected directly to the exhaust fan 100 so that the output of the exhaust fan 100 can be controlled by an inverter according to the pressure in the dryer 14.

  The heater 12 is a device that applies the heat energy necessary for drying the latex to the gas using the heating steam supplied from the heating steam supply pipe 74. As the heater 12, in addition to this, an electric heater; a gas fuel typified by LPG (liquefied petroleum gas) or LNG (liquefied natural gas), or a liquid fuel typified by kerosene or light oil is directly combusted. A fire heater can be used.

  The dryer 14 is a device that reduces the moisture content of the sprayed latex to a specified level with a gas having a predetermined drying hot air temperature and dries it, and is connected to the cylindrical straight body portion and the lower end of the straight body portion. An inverted conical cone portion, a solid content outlet 124 provided at the tip of the cone portion, a gas discharge port 16 provided in the cone portion constituting the bottom portion, and a pressurized two-fluid spray nozzle ( (Not shown). The method of spraying latex is not limited to the pressurized two-fluid nozzle, and may be a spraying method using a pressurized nozzle or a disk atomizer. Here, the drying hot air temperature is the temperature of the gas at the inlet of the dryer 14.

  The collector 18 is a device that separates and collects solids contained in the circulating gas using a bag filter, and includes a cylindrical straight body portion and an inverted conical cone portion connected to the lower end of the straight body portion. , And a solid content outlet 126 provided at the tip of the cone portion. In addition to this, a gas-solid separator such as a cyclone can be used as the collector 18.

The gas cooling tower 20 is a direct heat exchanger represented by a wet scrubber or the like, and cools moisture in the gas increased by drying the latex by directly bringing cooling water having a temperature below the dew point into contact with the gas. The condensed water is taken out and the condensed water is taken out. In addition, as the gas cooling tower 20, an indirect heat exchanger represented by a known multi-tube heat exchanger or a heat exchanger with multi-tube fins can be used.
The gas cooling tower 20 is designed so that the amount of water condensed therein is equal to the total amount of water generated by LPG combustion in the hot stove 28 in addition to the amount of water evaporated from the latex.

  The hot stove 28 burns LPG with volatile components other than water, such as unreacted monomers and organic solvents, in a part of the gas extracted from the preheating gas channel 44 (hereinafter referred to as extracted gas). It is an apparatus that decomposes and deodorizes by bringing it into contact with the high temperature part generated, and further reduces the oxygen concentration in the extracted gas. As the fuel, in addition to LPG, gaseous fuel such as LNG (liquefied natural gas), or liquid fuel such as kerosene or light oil may be used. As the hot stove, a direct-fired combustion device, a regenerative combustion device, a catalytic combustion device, a contact combustion device, or the like can be used.

  As shown in FIG. 2, the control device 34 includes a storage unit 128, a monitoring unit 130, a control unit 132, and an interface unit 134. The control unit 34 is generally configured and includes a valve provided in the circulation drying device 10, It monitors, operates, and controls thermometers, pressure gauges, fans, and pumps. An example of such a process control system is DCS (Distributed Control System).

  The storage unit 128 is an operation procedure to be performed from the start of operation of the circulating drying apparatus 10 to the start of latex spraying; a plurality of operations including a single operation or a plurality of related operations set in advance by dividing these operations. Steps for setting valves, thermometers, pressure gauges, fans, and pumps in each operation; valves, thermometers, pressure gauges, fans provided in the circulation type drying apparatus 10 whose states should be checked at each step , And a checklist in which the pump is listed; The storage unit 128 is configured by a volatile memory such as a RAM (Random Access Memory), a nonvolatile memory such as a hard disk device, a magneto-optical disk device, or a flash memory, or a combination thereof.

  For each step, the monitoring unit 130 automatically determines whether the statuses of the valves, thermometers, pressure gauges, fans, and pumps listed in the check list of the storage unit 128 are the setting conditions of the storage unit 128. When the listed item is in the setting condition state, the controller 132 is instructed to move to the next step; if the listed item is not in the setting condition state, Those that are not in the set state are output to a display device to be described later, and these checks are repeated until the listed ones are in the set state.

The control unit 132 is based on the operation procedure stored in the storage unit 128, the setting conditions of the valve, thermometer, pressure gauge, fan, and pump in each operation, temperature information and pressure information from the thermometer and pressure gauge, and the like. Automatic valve opening / closing; control valve, fan, pump control, etc.
The interface unit 134 electrically connects a valve, a thermometer, a pressure gauge, a fan, a pump, and the like, and the monitoring unit 130 and the control unit 132.

The monitoring unit 130 and the control unit 132 may be realized by dedicated hardware, and the monitoring unit 130 and the control unit 132 are configured by a memory and a central processing unit (CPU). The functions may be realized by loading a program for realizing the functions of the monitoring unit 130 and the control unit 132 into a memory and executing the program.
In addition, an input device, a display device, and the like are connected to the control device 34 as peripheral devices. Here, the input device refers to an input device such as a display touch panel, a switch panel, or a keyboard, and the display device refers to a CRT or a liquid crystal display device.

<Driving method>
Next, the operation method of the circulation type drying apparatus of the present invention will be described by taking the circulation type drying apparatus of the illustrated example as an example.
In the operation method of the circulation type drying apparatus of the present invention, all operations from the start of operation of the circulation type drying apparatus to the start of spraying of the object to be dried are performed in one step or a plurality of steps including a plurality of related operations. Divide in advance; For each step, list the valves, thermometers, pressure gauges, fans, and pumps in the circulation dryer that should be checked in advance; list for each step It is a method of automatically checking whether or not the uploaded item is in a preset state; only when the listed item is in the set state, it automatically shifts to the next step.

  In the case of the circulation type drying apparatus 10 in the illustrated example, the operations from the start of operation to the start of spraying of the latex (the object to be dried) include a valve check step, a nitrogen replacement step, a gas circulation preparation step, a gas cooling tower preparation step, a gas Dividing into a circulation start step, an assist air start step, a hot stove purge step, a hot stove ignition step, and a temperature control step. Hereinafter, each step will be specifically described.

(Operation preparation-operation start)
The air knocker of the dryer 14, the bag filter air knocker of the collector 18, and the bag filter pulse air are activated, the circulation gate valve 76 is manually closed, and the collector inlet gate valve 78 and the collector outlet gate valve 80 are turned on. Open manually.

(Valve check step)
When the operation start button of the control device 34 is pressed, first, all the valves listed in the check list of the storage unit 128 are in a state where the automatic operation can be started (according to the setting conditions stored in the storage unit 128). The monitoring unit 130 checks whether or not Specifically, the collector inlet gate valve 78, the collector outlet gate valve 80, and the circulation opening valve 90 are open, and the circulation gate valve 76, branch flow valve 82, combustion gas return valve 84, cooling It is checked whether the gas outlet valve 88, the latex supply valve 92, the water supply valve 94 and the heating steam control valve 96 are closed.

  When all the valve states are in accordance with the set conditions, the process proceeds to the next step. Otherwise, the automatic valve is automatically switched according to the set condition by the control unit 132, and the manual valve that is not set is output to the display device and the manual valve is notified to the operator. The operator switches the manual valve as set. These checks are repeated by the monitoring unit 130 until all the listed valves are set.

(Nitrogen replacement step)
In accordance with the operation procedure stored in the storage unit 128, the control unit 132 opens a main plug (not shown) of a nitrogen gas cylinder (not shown), and starts supplying nitrogen gas from the nitrogen gas supply pipe 61 to the circulation dryer 10. . The monitoring unit 130 checks the oxygen concentration in the circulation system.
If the oxygen concentration in the circulation system is in accordance with the set conditions, the process proceeds to the next step. Otherwise, the monitoring unit 130 repeats the check until the oxygen concentration in the circulatory system reaches a set concentration.

(Gas circulation preparation step)
The circulation gate valve 76 is manually opened. Further, according to the operation procedure stored in the storage unit 128, the combustion gas return valve 84 is opened by the control unit 132 and the circulation opening valve 90 is closed, so that the gas can be circulated in the circulation type drying apparatus 10. The monitoring unit 130 checks whether all the valves listed in the check list of the storage unit 128 conform to the setting conditions stored in the storage unit 128. When all the valve states are in accordance with the set conditions, the process proceeds to the next step. Otherwise, the automatic valve is automatically switched according to the set condition by the control unit 132, and the manual valve that is not set is output to the display device and the manual valve is notified to the operator. The operator switches the manual valve as set. These checks are repeated by the monitoring unit 130 until all the listed valves are set.

(Gas cooling tower preparation step)
In accordance with the operation procedure stored in the storage unit 128, the control unit 132 starts the operation of the cooling water circulation pump 112, the refrigerant circulating pump 114, and the recooling tower fan 116, and operates with the set conditions stored in the storage unit 128. to continue. The monitoring unit 130 checks whether the temperature information of the cooling water sent from the cooling water thermometer 140 of the cooling water circulation channel 70 is within the set temperature range stored in the storage unit 128. If the temperature information from the thermometer is in accordance with the set conditions, the process proceeds to the next step. Otherwise, the monitoring unit 130 repeats the check until the temperature information from the thermometer is set. The temperature control of the cooling water is continued until the circulation type drying apparatus 10 is shut down.

(Gas circulation start step)
The operation of the cooling fan 104 is started by the control unit 132 in accordance with the operation procedure stored in the storage unit 128, and control of the pressure control valve 86 based on the pressure information from the cooling tower outlet pressure gauge 122 is started. Further, the operation of the blower fan 98 and the exhaust fan 100 is started, and the output control of the exhaust fan 100 based on the pressure information from the dryer pressure gauge 32 is started. Next, the output of the blower fan 98 is gradually increased to the set output stored in the storage unit 128. Accordingly, the pressure in the dryer 14 gradually increases, and as a result, the output of the exhaust fan 100 is gradually increased by the inverter so that the pressure in the dryer 14 is within the set range. Control of the pressure in the drying chamber of the exhaust fan 100 is continued until the circulation dryer 10 is shut down.

  Whether the air volume information from the air volume meter 138 of the preheating gas flow path 44 is within the range of the set air volume stored in the storage unit 128; the pressure information from the dryer pressure gauge 32 is stored in the storage unit 128 The monitoring unit 130 checks whether the pressure is within the set pressure range. If these pieces of information are in accordance with the set conditions, the process proceeds to the next step. Otherwise, the monitoring unit 130 repeats these checks until these pieces of information are set.

(Assist air start step)
In accordance with the operation procedure stored in the storage unit 128, the operation of the roots blower 106 is started by the control unit 132, and then the output of the roots blower 106 is gradually increased. The monitoring unit 130 checks whether the pressure information of the assist air from the pressurized two-fluid spray nozzle (not shown) is within the set pressure range stored in the storage unit 128. If the assist air pressure information is in accordance with the set condition, the output of the Roots blower 106 is stopped from increasing, and the process proceeds to the next step. Otherwise, the monitoring unit 130 repeats these checks until the assist air pressure information is set. The assist air pressure control is continued until the circulation dryer 10 is shut down.

(Hot stove purge step)
According to the operation procedure stored in the storage unit 128, the control unit 132 starts the operation of the branch fan 102 and opens the branch flow path valve 82. Next, the output of the branch fan 102 is gradually increased. The monitoring unit 130 checks whether the output of the branching fan 102 is within the range of the setting condition stored in the storage unit 128. If the output of the branch fan 102 is in accordance with the set condition, the control unit 132 stops the increase of the output of the branch fan 102 and proceeds to the next step. Otherwise, the monitoring unit 130 repeats these checks until the output of the branch fan 102 is set. The branching fan 102 is kept at the set output until the circulation drying apparatus 10 is shut down unless the operator changes it.

(Hot stove ignition step)
In accordance with the operation procedure stored in the storage unit 128, the control unit 132 starts the operation of the combustion fan 108 and starts supplying air to the hot stove 28. The monitoring unit 130 checks whether the pressure information from the cooling tower outlet pressure gauge 122 is within the set pressure range stored in the storage unit 128. If the pressure information from the cooling tower outlet pressure gauge 122 is in accordance with the set conditions, the control unit 132 opens the main plug (not shown) of the LPG gas cylinder (not shown), and the LPG gas from the LPG gas supply pipe 62 to the hot stove 28 is opened. Is started, the LPG gas in the hot stove 28 is ignited, and the process proceeds to the next step. Otherwise, the monitoring unit 130 repeats these checks until the pressure information from the cooling tower outlet pressure gauge 122 is set.

(Temperature adjustment step)
In the temperature adjustment step, the gas temperature rise by the hot stove 28 and the gas temperature rise by the heater 12 are simultaneously advanced.
In accordance with the operation procedure stored in the storage unit 128, the control unit 132 gradually opens the control valve (not shown) of the LPG gas, and at the same time, the output of the hot air fan 108 is gradually increased to supply the LPG gas and air to the hot air furnace 28. The amount of gas at the outlet of the hot stove 28 is gradually increased. The monitoring unit 130 checks whether the temperature information from the hot stove outlet thermometer 136 is within the set temperature range stored in the storage unit 128. If the temperature information from the hot stove outlet thermometer 136 is in accordance with the set conditions, the control unit 132 maintains the state of the LPG gas control valve and stops the increase in the output of the combustion fan 108. Otherwise, the monitoring unit 130 repeats these checks until the temperature information from the hot stove outlet thermometer 136 is set.

In raising the temperature of the gas by the heater 12, as shown below, the temperature of the gas is raised stepwise while repeating a plurality of heating steps.
According to the operation procedure stored in the storage unit 128, the control unit 132 opens the heating steam control valve 96 to a predetermined opening degree. At this time, the gas passing through the heater 12 is heated by the heating steam supplied through the heating steam supply pipe 74. When the gas is heated, the gas expands and the pressure of the gas in the dryer 14 increases, so that the output of the exhaust fan 100 is increased by the inverter, and the outlet pressure of the gas cooling tower 20 increases accordingly. Based on the pressure information from the cooling tower outlet pressure gauge 122, the control unit 132 automatically increases the opening of the pressure control valve 86, and the gas is gradually exhausted to the outside.

  When the pressure information from the cooling tower outlet pressure gauge 122 is set, the controller 132 automatically reduces the opening degree of the pressure control valve 86 again. And according to the operation procedure memorize | stored in the memory | storage part 128, the control part 132 opens the heating steam control valve 96 to the following predetermined opening degree. Then, since the temperature of the gas is further increased, the gas pressure rises again. Along with this, the opening degree of the pressure control valve 86 is automatically increased again by the control unit 132, and the gas is gradually exhausted to the outside.

The above temperature raising step is repeated until the temperature information from the dryer outlet thermometer 120 reaches a predetermined temperature.
When the outlet temperature of the dryer 14 exceeds a predetermined temperature (for example, 82 ° C.), the bag filter of the collector 18 is adversely affected by heat, so that the control unit 132 performs water treatment according to the operation procedure stored in the storage unit 128. The supply valve 94 is opened, and the operation of the liquid feed pump 110 is started. As a result, water is sprayed from the pressurized two-fluid spray nozzle, and the gas is cooled in the dryer 14.

  The monitoring unit 130 always checks whether the temperature information from the dryer outlet thermometer 120 is within the set temperature range stored in the storage unit 128. When the temperature information from the dryer outlet thermometer 120 exceeds the set temperature range, the controller 132 increases the output of the liquid feed pump 110. When the temperature information from the dryer outlet thermometer 120 falls below the set temperature range, the controller 132 reduces the output of the liquid feed pump 110.

  When the spraying of water from the pressurized two-fluid spray nozzle is started, that is, when the gas is heated to a predetermined temperature by the heater 12, the temperature raising step for raising the temperature in steps by the control unit 132 is stopped. Then, the heating steam control valve 96 is continuously opened to further raise the temperature of the gas passing through the heater 12. The monitoring unit 130 always checks whether the temperature information from the dryer inlet thermometer 118 is within the set temperature range stored in the storage unit 128. Here, the set temperature is the inlet temperature of the dryer 14 when the latex is dried. When the temperature information from the dryer inlet thermometer 118 exceeds the set temperature range, the controller 132 reduces the opening degree of the heating steam control valve 96. When the temperature information from the dryer inlet thermometer 118 falls below the set temperature range, the controller 132 increases the opening degree of the heating steam control valve 96.

(Latex spraying started)
The temperature information from the hot stove outlet thermometer 136 is within the set temperature range stored in the storage unit 128, and the temperature information from the dryer inlet thermometer 118 is set in the set temperature range stored in the storage unit 128. When inside, the control part 132 closes the water supply valve 94 and opens the latex supply valve 92. As a result, latex is sprayed from the pressurized two-fluid spray nozzle, and drying of the latex is started.

(Abnormality monitoring)
In each of the above steps, it is constantly monitored whether an abnormality has occurred in the circulation type drying apparatus 10. Specifically, for each step, a list of valves, thermometers, pressure gauges, fans, and pumps provided in the circulation dryer 10 that should be checked for abnormal states is listed in advance. Automatically check whether the listed item is in a preset abnormal state, and if the listed item is in the set abnormal state, it will be automatically selected according to the abnormal state. Perform the error handling operation.

  For example, after the gas circulation start step, output control of the exhaust fan 100 based on pressure information from the dryer pressure gauge 32 is always performed, and during this time, the pressure in the dryer 14 is simultaneously monitored by the monitoring unit 130. Is called. The state of the pressure in the dryer 14 is “HHHH”, “HHH”, “HH”, “HI”, “NR”, “LO”, “LL”, “LLL”, “LLLL” in descending order of pressure. And are stored in the storage unit 128.

  Here, “NR” is a normal pressure range, and “HI” and “LO” can immediately return the pressure to “NR” by opening the circulation opening valve 90, and to continue the operation. Pressure ranges with little impact, “HH” and “LL” are pressure ranges that have an impact on continuation of operation but are expected to recover pressure to “NR”, “HHH” and “LLL” "Is a pressure range where the pressure is not expected to recover to" NR ", and" HHHH "/" LLLL "are pressure ranges where the dryer 14 may burst / collapse, respectively.

When the pressure increases (or decreases) and falls outside the range of “NR” and becomes “HI” (or “LO”), the control unit 132 opens the circulation release valve 90 while continuing the operation, and the pressure is reduced to “NR”. Attempt to return to range. If the pressure returns to the range of “NR” by opening the circulation opening valve 90, the circulation opening valve 90 is closed.
When the pressure further increases (or decreases) and falls outside the range of “HI” (or “LO”) and becomes “HH” (or “LL”), the operation is interrupted with the circulation opening valve 90 opened, Wait until the pressure returns to “HI” (or “LO”).

If the pressure further increases (or decreases) and falls outside the range of “HH” (or “LL”) and becomes “HHH” (or “LLL”), the pressure cannot be restored to the normal state “NR”. Emergency stop the device.
If the pressure is further increased (or decreased) even after an emergency stop of the apparatus and is out of the range of “HHH” (or “LLL”) and becomes “HHHH” (or “LLLL”), Therefore, the vent valve of the dryer 14 is opened by the control unit 132 to prevent the dryer 14 from being destroyed.

(Dry object)
Examples of the latex include a polymer latex produced by a generally known emulsion polymerization method or a soap-free emulsion polymerization method. Examples of the polymer include aromatic vinyl monomers, vinyl cyanide monomers, ethylenically unsaturated carboxylic acid monomers, unsaturated carboxylic acid alkyl ester monomers, and vinyl halide monomers. And those obtained by homopolymerizing a polymer, a maleimide monomer, or the like, or those obtained by copolymerization, seed polymerization, or graft polymerization of two or more of them. Further, the polymer latex may be one kind alone or a mixture of plural kinds of latexes.

  In the operation method of the circulation type drying apparatus 10 described above, all operations from the start of operation of the circulation type drying apparatus 10 to the start of spraying latex are performed by one operation or a plurality of related operations. In each step, a list of valves, thermometers, pressure gauges, fans, and pumps provided in the circulation type drying apparatus 10 whose conditions should be checked is listed in advance; Each time it automatically checks whether the listed one is in a preset state; it only moves to the next step when the listed one is in a set state. When each step is in a stable state, it is possible to proceed to the next step, and it is difficult for an abnormality to occur in the apparatus.

  Moreover, even when an abnormality occurs in the apparatus, it is easy to identify the cause. That is, when an abnormality occurs, the operation immediately before that is considered to be the cause. Therefore, if the valves, thermometers, pressure gauges, fans, and pumps listed due to the occurrence of an abnormality do not enter the set state and do not proceed to the next step, What is necessary is just to investigate mainly the valve, the fan, the pump, the apparatus provided with these, the flow path, etc. in which the operation in the step is performed.

  Furthermore, if the operation continues with the abnormality still occurring, there is a high possibility that another abnormality will be induced or a serious trouble such as an emergency stop of the device will occur. Therefore, if the valves, thermometers, pressure gauges, fans, and pumps that are listed are not in the set state and the next step is not performed, this does not happen.

  Further, in the operation method of the circulation type drying apparatus 10 described above, the heater is used while exhausting excess gas by the pressure control valve 86 and controlling the pressure so that the gas pressure is within a predetermined range. 12 has a plurality of heating steps in which the temperature of the gas is raised stepwise up to a predetermined temperature; the pressure of the gas is checked at the outlet pressure gauge 122 for cooling at each temperature rising step; the gas pressure is below a predetermined value Then, since the process proceeds to the next temperature raising step, the gas pressure exceeds the normal pressure range, and no abnormality occurs in the apparatus. That is, since the opening / closing operation of the pressure control valve 86 is very slow, if the temperature of the gas is raised to a predetermined temperature at once, the pressure control by the pressure control valve 86 cannot follow a rapid pressure increase. If the temperature is raised stepwise and the next temperature raising step is not performed until the gas pressure becomes normal, the pressure control by the pressure control valve 86 can sufficiently follow the pressure change. The gas pressure can be kept in the normal pressure range.

  Further, in the operation method of the circulation type drying apparatus 10 described above, the output of the exhaust fan 100 that sucks the gas in the dryer 14 is controlled so that the pressure in the dryer 14 is within a predetermined range. Therefore, the pressure of the gas in the dryer 14 exceeds the normal pressure range, and no abnormality occurs in the dryer 14.

  According to the operation method of the circulation type drying apparatus of the present invention, even if the operation from the start of operation to the start of spraying of the object to be dried is automatically performed, it is difficult for the abnormality to occur, and the cause of the abnormality can be easily identified. In addition, since it does not lead to a serious trouble, the number of workers can be reduced more than before, and even if an abnormality occurs, the worker can concentrate on dealing with the abnormality.

It is a schematic block diagram which shows an example of a circulation type drying apparatus. It is a block diagram which shows an example of the control apparatus in a circulation type drying apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Circulation-type drying apparatus, 12 ... Heater, 14 ... Dryer, 32 ... Dryer pressure gauge, 76 ... Circulation gate valve, 78 ... Collector inlet gate valve, 80 ... Collector outlet gate valve, 82 ... Branch flow path valve, 84 ... Combustion gas return valve, 86 ... Pressure control valve, 88 ... Cooling gas outlet valve, 90 ... Circulation release valve, 92 ... Latex supply valve, 94 ... Water supply valve, 96 ... Heating steam control valve, DESCRIPTION OF SYMBOLS 98 ... Blower fan, 100 ... Exhaust fan, 102 ... Branch fan, 104 ... Cooling fan, 106 ... Assist air fan, 108 ... Air blower fan, 110 ... Liquid feed pump, 112 ... Cooling water circulation pump, 114 ... Refrigerant body circulation Pump: 116 ... Recooling tower fan, 118 ... Dryer inlet thermometer, 120 ... Dryer outlet thermometer, 122 ... Cooling tower outlet pressure gauge, 136 ... Hot stove outlet thermometer, 138 ... Air flow meter, 140 ... Cooling water thermometer

Claims (3)

An operation method of a circulation type drying apparatus for drying an object to be dried sprayed in a dryer by a gas heated by the heater while circulating the gas between the heater and the dryer,
All operations from the start of operation of the circulation type drying apparatus to the start of spraying of an object to be dried are divided in advance into a plurality of steps consisting of one operation or a plurality of related operations,
For each step, list in advance the valves, thermometers, pressure gauges, fans, and pumps that should be checked for their status in the circulation dryer,
At each step, it automatically checks whether the listed items are in a preset state,
A method for operating a circulation type drying apparatus, wherein the process automatically shifts to the next step only when the listed items are set. During the period from the start of operation of the circulation dryer to the start of spraying of the object to be dried, the exhaust gas is exhausted to control the pressure so that the gas pressure is within the predetermined range, and the gas is Having a plurality of temperature raising steps for gradually raising the temperature to a temperature;
Check the gas pressure at each heating step,
2. The method of operating a circulation type drying apparatus according to claim 1, wherein when the gas pressure falls within a predetermined range, the process proceeds to the next temperature raising step. The operation method of the circulation type drying apparatus according to claim 1 or 2, wherein the exhaust fan for sucking the gas in the dryer is controlled so that the pressure in the dryer is within a predetermined range.

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