JP2007229379A - Steam heating apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steam heating apparatus inexpensively and stably controlling the temperature by preventing hunting of a steam feed operation valve consisting of a solenoid valve. <P>SOLUTION: This steam heating apparatus is provided with a treatment tank 1 storing heating object 7, a steam feed means 2 feeding steam to the treatment tank 1 via the steam feed operation valve 15, and a control means 9 controlling the opening/closing of the steam feed operation valve 15 to retain the pressure in the treatment tank 1 at a target value. The control means 9 converts the changeably set temperature target value to a pressure target value, and controls the opening/closing of the steam feed operation valve 15, which consists of the solenoid valve, based on the detection signal of a pressure sensor 6 and retains the interior of the treatment tank 1 to the pressure target value. The control means 9 varies a difference between an upper limit value and a lower limit value of the pressure when retaining to the pressure target value according to which one of a plurality of preset temperature ranges the temperature target value is pertained. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a steam heating apparatus for supplying steam into a treatment tank in which an object to be heated is accommodated to heat the object to be heated. In particular, the present invention relates to a steam heating device as a steam cooking device for cooking food to be cooked (food or food).

A steam heating device typified by a steaming device disclosed in Patent Document 1 below is a device that supplies steam into a processing tank and heats an object to be heated accommodated in the processing tank. In such a steam heating device, the temperature adjustment in the processing tank conventionally involves monitoring the pressure in the processing tank, and supplying steam to the processing tank (steaming) and condensing the supplied steam. It is controlled by heat dissipation and, in some cases, evacuation from the inside of the treatment tank. At this time, it is preferable that the steam supply into the treatment tank is provided with a proportional control valve in the steam introduction pipe and the opening degree thereof is adjusted. In many cases, an upper limit value and a lower limit value for temperature are set, and on / off control is performed to open and close between the upper and lower limit values.
JP-A-9-266856

  However, the relationship between saturated steam temperature and saturated steam pressure is not constant for the same temperature change. That is, even with the same temperature difference, the pressure change decreases as the temperature decreases, and the pressure change increases as the temperature increases. Therefore, if the difference (control differential) between the upper and lower limit values for on / off control of the solenoid valve is constant, hunting of the solenoid valve is likely to occur particularly in a low temperature range, and appropriate control may not be performed.

  The problem to be solved by the present invention is to provide a steam heating apparatus capable of performing stable temperature control at a low cost while preventing hunting.

  The present invention has been made in order to solve the above-mentioned problems. The invention according to claim 1 is to supply steam into the processing tank through a processing tank in which an object to be heated is accommodated and a steam supply operation valve. When controlling the opening and closing of the steaming operation valve so as to maintain the pressure or temperature in the treatment tank or the temperature of the object to be heated at a target value, prevent the hunting of the steaming operation valve. And a hunting prevention means.

  According to the first aspect of the present invention, even if the steaming operation valve is composed of an electromagnetic valve or a motor valve, hunting of the steaming operation valve can be prevented by the hunting prevention means, and stable temperature control can be performed at low cost. Can do.

  According to a second aspect of the present invention, the anti-hunting means is means for varying a difference between an upper limit value and a lower limit value in accordance with the target value with respect to the pressure or temperature when maintaining the target value. The steam heating apparatus according to claim 1.

  According to the second aspect of the invention, the control control of the pressure or temperature can be stably performed at a low cost by changing the control differential according to the target value.

  According to a third aspect of the present invention, there is provided a decompression means for decompressing the inside of the treatment tank, a return pressure means for restoring the decompressed inside of the treatment tank, and discharging steam and / or condensed water from the treatment tank to the outside. Discharging means, a pressure sensor for detecting the pressure in the processing tank, a temperature sensor for detecting the temperature of the object to be heated, and the pressure sensor or the temperature so as to maintain the pressure or temperature at the target value. Control means for controlling the opening and closing of the steaming operation valve based on the detection signal of the sensor, this control means, depending on which of the predetermined pressure range or temperature range the target value belongs, 3. The steam heating apparatus according to claim 2, further comprising: the hunting preventing unit that varies a difference between an upper limit value and a lower limit value of the pressure or temperature when maintaining the target value. 4.

  According to the third aspect of the present invention, the maintenance control of the pressure or temperature can be made inexpensively and stably by changing the control differential depending on which of the plurality of predetermined pressure ranges or temperature ranges the target value belongs to. This can be done easily.

  The invention according to claim 4 is the steam heating apparatus according to claim 3, wherein the difference between the upper limit value and the lower limit value is set larger as the pressure or temperature becomes lower.

  According to the fourth aspect of the present invention, it is possible to prevent hunting of the steam supply operation valve particularly in a low temperature range in consideration of the relationship between the saturated steam temperature and the saturated steam pressure.

  According to a fifth aspect of the present invention, the control means converts the temperature target value set to be changeable into a pressure target value, and maintains the inside of the processing tank at the pressure target value. The hunting prevention means is configured to control opening and closing of the steam supply operation valve including an electromagnetic valve based on a detection signal, and the hunting preventing means is configured to control the pressure depending on which of the predetermined temperature ranges the temperature target value belongs to The steam heating device according to claim 3 or 4, wherein a difference between an upper limit value and a lower limit value of the pressure when maintaining the target value is made different.

  According to the fifth aspect of the present invention, simple and reliable control is possible by controlling the opening and closing of the steam supply operation valve based on the pressure in the processing tank while setting the target value by temperature.

  According to a sixth aspect of the present invention, the steam supply means includes the steam introduction pipe that supplies the steam from the steam generator into the processing tank, and the electromagnetic valve provided in the middle of the steam introduction pipe. A steam supply operation valve, and the hunting prevention means includes a motor valve provided sequentially with the electromagnetic valve in the steam introduction pipe, and the electromagnetic valve and the motor valve are controlled to be opened and closed simultaneously. The steam heating apparatus according to claim 1.

  According to the sixth aspect of the present invention, a combination of a solenoid valve and a motor valve is used in series, and by simultaneously controlling opening and closing of these, the hunting of the steam supply operation valve is performed using a delay corresponding to the operation time of the motor valve. Can be prevented.

  Further, in the invention according to claim 7, the steam supply means includes a steam introduction pipe for supplying the steam from the steam generator into the processing tank, and an electromagnetic valve provided in the middle of the steam introduction pipe. The steam heating device according to claim 1, wherein the steam supply operation valve is controlled to be opened and closed while being unopenable within a predetermined time from the closing thereof.

  According to the seventh aspect of the present invention, it is possible to prevent hunting of the steaming operation valve by providing a limit on the minimum time until the steaming operation valve is once closed and then opened again.

  According to the steam heating apparatus of the present invention, it is possible to perform inexpensive and stable temperature control.

Next, an embodiment of the present invention will be described.
The present invention is a steam heating apparatus that heats an object to be heated contained in a treatment tank with steam. This steam heating apparatus includes a processing tank in which an object to be heated is stored, a steam supply means for supplying steam to the processing tank via a steaming operation valve, and hunting prevention for preventing hunting of the steaming operation valve. Means. Furthermore, in the present embodiment, a decompression means for decompressing the inside of the treatment tank, a return pressure means for restoring the pressure inside the decompressed treatment tank, a discharge means for discharging the steam and its condensed water to the outside, and a treatment A pressure sensor for detecting the pressure in the tank; a temperature sensor for detecting the temperature of the object to be heated; and a control means for controlling the means based on detection signals of the sensors.

  Here, although the said to-be-heated material does not ask | require especially, let it be to-be-cooked objects, such as a foodstuff or foodstuff, for example. In this case, the steam heating device can be referred to as a steam cooking device. Alternatively, the object to be heated may be an object to be sterilized such as a scalpel for operation. In this case, the steam heating device can be referred to as a steam sterilization device.

  The treatment tank is a metal can body that is formed in a hollow structure so as to accommodate an object to be heated and is typically formed in a substantially rectangular box shape. This processing tank has a hollow portion that opens to one side surface, and the opening portion can be opened and closed by a door. In a state where the door is closed, the hollow portion is sealed. However, the configuration of the treatment tank is not limited to this, and the pan-like container that opens only upward may be configured such that its upper opening can be closed with a lid.

  The steam supply means is means for supplying steam from the boiler into the treatment tank. This steam is preferably a clean steam obtained by heating pure water or soft water in a secondary boiler (reboiler) using steam from the primary boiler as a heat source. Thereby, boiler water treatment chemicals, such as rust in piping and a rust preventive agent, are not sanitized and are hygienic. The steam from the steam supply means is supplied into the treatment tank through a steam supply line as a steam introduction conduit. By opening and closing the steaming operation valve provided in the middle of the steaming line, the presence or absence of steam supply to the treatment tank can be switched.

  The decompression means is means for decompressing the inside of the processing tank by evacuating the air or steam in the processing tank. The decompression means includes a vacuum pump or a steam ejector or a water ejector instead of or in addition to the vacuum pump. The decompression means is connected to the treatment tank via a decompression line as an air outlet conduit. By opening and closing a pressure reducing operation valve provided in the middle of the pressure reducing line, whether or not evacuation from the processing tank is possible is switched. Alternatively, by controlling the operation of a vacuum pump or the like, whether or not evacuation can be performed from within the processing tank can be switched.

  The decompression means preferably further includes a heat exchanger. This heat exchanger cools and condenses the vapor | steam in the air attracted | sucked from the inside of a processing tank. In order to perform this cooling and condensation action, water is supplied to the heat exchanger, and the pressure reduction line is cooled. By preliminarily condensing the vapor in the decompression line with a heat exchanger, it is possible to reduce the load on the subsequent vacuum pump and increase the decompression capability.

  The return pressure means is means for returning the pressure in the treatment tank decompressed by the pressure reduction means. Specifically, the outside air can be introduced into the decompressed treatment tank and the pressure inside the treatment tank can be restored to atmospheric pressure. It is desirable to introduce outside air into the treatment tank through a filter in consideration of hygiene. The clean air that has passed through the filter is supplied into the treatment tank via a return pressure line as an air introduction pipe line. By opening and closing a return pressure operation valve provided in the middle of the return pressure line, the presence or absence of introduction of outside air into the processing tank can be switched.

  The discharge means is means for discharging the steam in the treatment tank and its condensed water to the outside. This discharging means is composed of a steaming line as a steam outlet line for discharging steam from the processing tank and a draining line as a drain line for discharging condensed water from the bottom of the processing tank through a steam trap. Is done. Here, by connecting the steaming line to the bottom of the treatment tank, the condensed water can be discharged in addition to the steam.

  A steaming operation valve is provided in the middle of the steaming line from the treatment tank. A drainage operation valve is provided in the middle of the drainage line from the treatment tank. By opening and closing the exhaust steam operation valve and / or the drain operation valve, whether or not steam and / or condensed water is discharged from the processing tank is switched.

  By the way, it is preferable that the decompression operation valve, the return pressure operation valve, and the exhaust steam operation valve are configured to be adjustable in opening. In this case, the respective capacities can be adjusted for the decompression in the treatment tank by the decompression means, the return pressure in the treatment tank by the decompression means, and the steaming out of the treatment tank by the discharge means. Further, the pressure reducing capability of the pressure reducing means such as an ejector may be adjusted. On the other hand, for the steaming operation valve, it is originally preferable that the steaming ability into the processing tank by the steaming means can be adjusted, and the opening degree can be adjusted. Solenoid valves that take either open or closed alternatives are used.

  The control means is means for controlling the steam supply means, the decompression means, the decompression means, the discharge means, and the like. Conversely, these means are controlled by the control means, and predetermined operation steps are sequentially executed in accordance with a preset program. In that case, it controls using the detection pressure from the pressure sensor which detects the pressure in a processing tank, the detection temperature from the temperature sensor which detects the temperature of the to-be-heated object in a processing tank, and elapsed time.

  Typically, the opening and closing of the steam supply operation valve is controlled based on the detected pressure of the pressure sensor to adjust the pressure in the processing tank and thus the temperature. Then, a desired end condition is satisfied such that the pressure or temperature in the processing tank or the temperature of the heated object in the processing tank is maintained at the target value for a set time, or the temperature of the heated object reaches the set temperature. And the heat treatment of the object to be heated is completed.

  During such heat treatment, the control means can control the opening and closing of the steam supply operation valve so as to maintain the pressure or temperature in the treatment tank or the temperature of the object to be heated in the treatment tank at the target value. At this time, an upper limit value and a lower limit value with respect to the target value are set, and on / off control of the steam supply operation valve is performed between the upper and lower limit values. That is, the steam supply operation valve is closed when the upper limit value is exceeded, while the steam supply operation valve is opened when the lower limit value is not reached, based on the detection signal of the pressure sensor or temperature sensor. Controls the opening and closing of the operation valve.

  The hunting prevention means is means for preventing hunting of the steaming operation valve, particularly during the maintenance control to the target value. The specific configuration of the hunting prevention means is not particularly limited, and for example, the following three embodiments can be given.

  The hunting prevention means of the first embodiment is means for varying the difference (control differential) between the upper limit value and the lower limit value of the pressure or temperature when maintaining the target value according to the target value. In this case, the hunting prevention means constitutes a part of the control means. Then, the hunting prevention means sets an upper limit value and a lower limit value with respect to the temperature target value using a preset calculation formula, and controls the opening and closing of the steam supply operation valve. At this time, the upper limit value and the lower limit value are set so that the difference between the upper limit value and the lower limit value varies depending on the target value.

  However, depending on which of a plurality of predetermined pressure ranges or temperature ranges the target value belongs to, the difference between the upper limit value and the lower limit value of the pressure or temperature when maintaining the target value is different. It is easy to do. In this case, for each pressure range or temperature range, a control differential is set in advance, and according to the target value input or selected, the control differential of the pressure range or temperature range to which the target value belongs, Based on the target value, the upper limit value and the lower limit value are determined.

  In any case, in consideration of the relationship between the saturated steam temperature and the saturated steam pressure, the difference between the upper limit value and the lower limit value is set to be larger as the pressure or temperature is lower. That is, when the target temperature is high, the control differential is reduced, and when the target temperature is low, the control differential is increased. Thereby, it is possible to prevent hunting of the steam supply operation valve particularly in a low temperature range.

  The hunting prevention means of the second embodiment includes a motor valve provided sequentially with the steaming operation valve in the steaming line, and simultaneously controls the opening and closing of the steaming operation valve and the motor valve. In this case, the motor valve is arranged in series with the solenoid valve constituting the steam supply operation valve, so that even if an opening command is issued to both valves at the same time, the solenoid valve is immediately opened. It will be gradually opened up. And as a total, the steam supply line is gradually opened. By utilizing such a delay corresponding to the operating time of the motor valve, it is possible to prevent hunting of the steam supply operation valve.

  The hunting prevention means of the third embodiment controls the opening and closing of the steaming operation valve composed of an electromagnetic valve while disabling it within a predetermined time from the closing thereof. In this case, the hunting prevention means constitutes a part of the control means, starts a timer when the steaming operation valve is closed, and prevents the steaming operation valve from being opened within a predetermined time. . By setting a limit on the minimum time until the steam supply operation valve is once closed and then opened again, hunting of the steam supply operation valve can be prevented.

  The operation method of the steam heating apparatus having the above configuration is not particularly limited, but typically, the heating step is performed after the air exclusion step. Here, an air exclusion process is a process of discharging the air in a processing tank in the state which stored the to-be-heated object in the processing tank. Moreover, a heating process is a process of supplying a vapor | steam in a processing tank by a steam supply means, and heating a to-be-heated material. At this time, the object to be heated may be heated with the steam supplied into the processing tank while the pressure in the processing tank is higher than the atmospheric pressure. The object to be heated may be heated while being heated.

  In this heating step, the pressure or temperature in the treatment tank or the temperature of the object to be heated in the treatment tank is controlled to be maintained at the target value. At this time, the target value may be changed in a plurality of stages. During such processing, hunting of the steaming operation valve is prevented by the hunting prevention means.

Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a first embodiment of the steam heating apparatus of the present invention, and shows an example applied to a steam cooking apparatus. As shown in this figure, the steam heating apparatus of the present embodiment includes a processing tank 1 that can be opened and closed with a hollow structure, steam supply means 2 that supplies steam into the processing tank 1, air in the processing tank 1, Decompression means 3 for reducing the pressure inside the processing tank 1 by sucking and discharging the steam to the outside, return pressure means 4 for returning the pressure by introducing outside air into the processing tank 1 under reduced pressure, steam in the processing tank 1 and its condensation The temperature of the discharge means 5 for discharging water to the outside, the pressure sensor 6 for measuring the pressure in the treatment tank 1, and the cooking object (food or food) 7 as the object to be heated contained in the treatment tank 1 A temperature sensor 8 to be measured and a control means 9 for controlling the means 2, 3, 4 and 5 based on the outputs of the sensors 6 and 8 are provided.

  The processing tank 1 of the present embodiment is a metal can body that includes a processing tank main body 10 that opens to one side surface and has a hollow portion, and a door 11 that opens and closes the opening of the processing tank main body 10. Since it is such a structure, the hollow part of the processing tank main body 10 is sealed by closing the door 11. The to-be-cooked object 7 may be accommodated in the processing tank 1 via a wagon (not shown) that is taken in and out of the processing tank 1, or a shelf plate 12 is provided in the processing tank 1 as shown in the illustrated example. You may respond by doing. Moreover, the to-be-cooked object 7 may be put in an appropriate container 13 and accommodated in the processing tank 1. Thus, the temperature of the to-be-cooked object 7 accommodated in the processing tank 1 is measured by the temperature sensor 8. In the present embodiment, the temperature sensor 8 is inserted into the cooking object 7 and detects the temperature of the cooking object 7.

  A steam supply means 2 is connected to the processing tank 1 so that steam can be supplied into the processing tank 1. The steam supply means 2 of this embodiment includes a primary boiler and a secondary boiler (reboiler) (not shown), uses the steam from the primary boiler as a heat source, changes soft water to steam in the secondary boiler, and so on. The generated clean steam is supplied into the treatment tank 1. Although a primary boiler is comprised from a normal common boiler, there exists a possibility that boiler water treatment chemicals, such as rust in a piping and a rust preventive agent, may mix in the steam by such a primary boiler. However, the steam supplied into the treatment tank 1 can directly come into contact with the object 7 to be cooked. Therefore, clean water is generated by changing soft water to steam in the secondary boiler, and this clean steam is supplied into the treatment tank 1.

  Clean steam from the secondary boiler is supplied into the treatment tank 1 via the steam supply line 14. A steam supply operation valve 15 is provided in the middle of the steam supply line 14. This steam supply operation valve 15 is sufficient if it can be configured to switch the presence or absence of steam supply into the treatment tank 1, and is configured by an electromagnetic valve that cannot be adjusted in opening degree and takes either an open state or a closed state. . By opening and closing the steam supply operation valve 15, the pressure in the processing tank 1 and thus the temperature can be adjusted. However, the pressure in the treatment tank 1 can be adjusted by controlling not only the steam supply operation valve 15 but also the decompression means 3.

  The processing tank 1 is connected to a decompression means 3 that evacuates the air and steam in the processing tank 1 to decompress the processing tank 1. In this embodiment, a pressure reducing operation valve 17, a heat exchanger 18, a check valve 19, and a water ring vacuum pump 20 are sequentially connected to the processing tank 1 through the pressure reducing line 16. The pressure reducing operation valve 17 of the present embodiment has a configuration capable of adjusting the opening, such as a proportional control valve or a motor valve.

  Water is supplied to the vacuum pump 20 via a sealed water supply valve 21, and the waste water from the vacuum pump 20 is discharged to a drain port (not shown). The sealed water supply valve 21 is opened in conjunction with the vacuum pump 20. In addition, cooling water is also supplied to the heat exchanger 18 through the heat exchange water supply valve 22 and drained to the drain outlet. By supplying the cooling water to the heat exchanger 18, the steam in the decompression line 16 can be cooled and condensed.

  The treatment tank 1 is connected to a decompression means 4 for decompressing after being decompressed by the decompression means 3. The return pressure means 4 of the present embodiment is provided with a return pressure line 23 connected to the processing tank 1 so as to be able to communicate with the outside air via a sterilization filter 24. In the middle of the return pressure line 23, a return pressure operation valve 25 is provided so as to be openable and closable. By opening the return pressure operation valve 25, the inside of the processing tank 1 can be opened to atmospheric pressure.

  The treatment tank 1 is connected to a discharge means 5 for discharging the steam in the treatment tank 1 and its condensed water to the outside. The discharging means 5 is divided into a steaming means 26 for discharging steam and air in the processing tank 1 to the outside, and a draining means 27 for discharging condensed water generated in the processing tank 1 to the outside. .

  The steaming means 26 is a means for leading the air and steam in the processing tank 1 out of the processing tank 1 through the steaming line 28. In the middle of the steaming line 28, a steaming control valve 29 such as a proportional control valve or a motor valve whose opening degree can be adjusted is provided. In the illustrated example, the exhaust steam line 28 is connected to the lower part of the treatment tank 1, but instead of this, or in addition to this, a similar exhaust steam line (not shown) is also provided at the upper part of the treatment tank 1. Can do. The steaming line 28 from the lower part of the processing tank 1 can also be used for discharging condensed water accumulated in the lower part of the processing tank 1 to the outside.

  On the other hand, the drainage means 27 includes a drainage line 31 having a steam trap 30, and the condensed water accumulated at the bottom of the treatment tank 1 through the drainage line 31 can be drained out of the treatment tank 1. And in the middle of this drainage line 31, the drainage operation valve 32 comprised from an electromagnetic valve is provided.

  Furthermore, the processing tank 1 is provided with a pressure sensor 6. The pressure in the processing tank 1 is detected by the pressure sensor 6. However, it is also possible to use a temperature sensor (not shown) instead of the pressure sensor 6. Any sensor can be used by converting pressure and temperature.

  The steam supply means 2, the decompression means 3, the return pressure means 4, the discharge means 5 and the like are controlled by a control means 9. The control means 9 is a controller 33 for controlling the means 2, 3, 4 and 5 based on the elapsed time grasped by the control means 9 and detection signals from the pressure sensor 6 and the temperature sensor 8. Specifically, the steam supply operation valve 15, the pressure reduction operation valve 17, the vacuum pump 20, the sealed water supply valve 21, the heat exchange water supply valve 22, the return pressure operation valve 25, the steaming operation valve 29, the drain operation valve 32, the pressure The sensor 6 and the temperature sensor 8 are connected to the controller 33. And the controller 33 performs the cooking of the to-be-cooked thing 7 in the processing tank 1 according to a predetermined procedure (program).

  In the present embodiment, the controller 33 can control the opening and closing of the steam supply operation valve 15 based on the pressure detected by the pressure sensor 6 so that the pressure in the processing tank 1 is maintained at the target value. Here, the target value is set in the controller 33 so as to be changeable by the setting unit 34. At that time, the pressure target value may be set, or the temperature target value may be set. When setting with a temperature target value, the controller 33 converts into pressure and processes. In any case, the controller 33 sets an upper limit value and a lower limit value for the target value in order to maintain the inside of the processing tank 1 at the pressure target value.

  At that time, the difference (control differential) between the upper limit value and the lower limit value is changed according to the target value by the hunting prevention means incorporated as a part of the controller 33. For example, the control differential is set in three temperature ranges, and based on the temperature target value set by the setting device 34 and the control differential to which it belongs, the pressure target value for maintaining the target value is set. An upper limit value and a lower limit value are set.

  Then, the controller 33 closes the steam supply operation valve 15 if the upper limit value is exceeded, while maintaining the pressure in the processing tank 1 at the target value by opening the steam supply operation valve 15 if it falls below the lower limit value. . By the way, in consideration of the relationship between the saturated steam temperature and the saturated steam pressure, the control differential is set to be larger in the temperature range where the pressure or the temperature becomes lower. The reason is that the temperature change gradient with respect to the pressure of the saturated steam temperature-pressure characteristic curve becomes smaller as the pressure increases, so if the same differential is set in the low pressure region and high pressure region This is because, in a region where the pressure (temperature) is low, the steam supply operation valve opens and closes due to slight pressure fluctuations. In the first embodiment, since the control differential is set to be larger in the temperature range where the pressure or temperature is lower, the opening / closing of the steam supply operation valve 15 is controlled while preventing the hunting of the steam supply operation valve 15. .

  When using the steam heating device, the object 7 to be cooked is accommodated in the processing tank 1 and the door 11 of the processing tank 1 is closed. In this initial state, the steam supply operation valve 15, the pressure reducing operation valve 17, the sealed water supply valve 21, and the heat exchange water supply valve 22 are closed, and the vacuum pump 20 is stopped in operation, and the return pressure operation valve 25 and the exhaust steam control valve are stopped. The operation valve 29 and the drain operation valve 32 are opened. And from this state, typically, an air exclusion process and a heating process are sequentially performed.

  In the air exclusion process, the decompression means 3 is operated with the steam supply operation valve 15, the return pressure operation valve 25, the exhaust steam operation valve 29 and the drain operation valve 32 closed. However, here, the heat exchanger 18 is not functioned, and only the vacuum pump 20 is operated to depressurize the inside of the processing tank 1. That is, with the heat exchange water supply valve 22 closed, the pressure reducing operation valve 17 and the sealed water supply valve 21 are opened to operate the vacuum pump 20. In this way, the air in the processing tank 1 is evacuated to the outside by the decompression means 3 and the air in the processing tank 1 is eliminated, thereby effectively cooking the cooking object 7 in the subsequent heating step. Can be done.

  Such air exclusion from the processing tank 1 may be performed up to a set pressure by using the pressure sensor 6 or may be performed only for a set time. Furthermore, this air exclusion process can also be performed by supplying steam into the treatment tank 1 with the steam supply operation valve 15 opened. Further, this air exclusion step can be omitted if necessary.

  In the heating process, steam is supplied into the processing tank 1 to cook the cooking object 7 in the processing tank 1. Specifically, the depressurization operation valve 17, the sealed water supply valve 21, the heat exchange water supply valve 22, the return pressure operation valve 25, and the exhaust steam operation valve 29 are closed and the operation of the vacuum pump 20 is stopped. The operation valve 15 is opened to supply steam into the treatment tank 1. At this time, when the inside of the treatment tank 1 exceeds the atmospheric pressure, the drainage operation valve 32 is opened to discharge condensed water from the bottom of the treatment tank 1 to the outside.

  In this way, steam is supplied into the processing tank 1 by the steam supply means 2 until the inside of the processing tank 1 reaches a desired set pressure. And the steam supply to the processing tank 1 by the steam supply means 2 is adjusted based on the detected pressure of the pressure sensor 6 so as to keep the inside of the processing tank 1 at the set pressure, and the cooked object 7 in the processing tank 1 Is cooked. During this heating process, the set pressure may be changed up and down stepwise.

  By the way, the cooking of the food 7 to be cooked by supplying steam into the treatment tank 1 is pressureless cooking performed at atmospheric pressure, pressure cooking performed at a pressure exceeding atmospheric pressure, and the decompression means 3 is operated when desired. And steaming under reduced pressure at a pressure lower than atmospheric pressure.

  In the case of non-pressure steaming, the pressure reducing operation valve 17, the sealed water supply valve 21, the heat exchange water supply valve 22, and the return pressure operation valve 25 are closed and the operation of the vacuum pump 20 is stopped, The steam operation valve 29 and the drain operation valve 32 are opened, and steam is supplied into the treatment tank 1.

  In the case of pressurized steaming, the depressurization operation valve 17, the sealed water supply valve 21, the heat exchange water supply valve 22, the return pressure operation valve 25, and the exhaust steam operation valve 29 are closed and the operation of the vacuum pump 20 is stopped. The steam operation valve 15 and the drain operation valve 32 are opened to supply steam into the treatment tank 1. Therefore, in the case of pressurized steaming, the condensed water is automatically discharged from the drain line 31 to the outside.

  In the case of steaming under reduced pressure, the steam supply operation valve 15 is opened and the steam is supplied into the treatment tank 1 with the decompression operation valve 25, the exhaust steam operation valve 29, and the drain operation valve 32 closed. At this time, when the inside of the processing tank 1 exceeds the set upper limit pressure, the decompression means 3 is operated to decompress the inside of the processing tank 1 to the set lower limit pressure. That is, when the pressure reducing operation valve 17, the sealed water supply valve 21, and the heat exchange water supply valve 22 are opened, the vacuum pump 20 is operated to depressurize the inside of the treatment tank 1 to the set lower limit pressure. The valves 17, 21, 22 are closed and the operation of the vacuum pump 20 is stopped.

  In any case, basically, the steam supply operation valve 15 is maintained so that the pressurization factor in the treatment tank 1 by the supply of steam and the decompression factor in the treatment tank 1 by the condensation of the supplied steam are kept in balance. Is heated and cooked while maintaining the pressure in the treatment tank 1 at the target value. However, in the case of reduced-pressure steaming, if the set upper limit pressure is exceeded, the decompression means 3 may be operated as described above. During maintenance control at such a pressure target value, as described above, hunting of the steam supply operation valve 15 is prevented by the hunting prevention means.

  In this way, in the heating step, the cooking object 7 accommodated in the processing tank 1 can be cooked by supplying steam into the processing tank 1. At this time, as described above, the steam supplied into the processing tank 1 is clean steam generated from soft water in the secondary boiler. Therefore, safe and reliable cooking can be realized. Moreover, uniform heating dishes are made in a short time by spreading clean steam around the entire periphery of the object 7 to be cooked.

  In the heating step, the temperature in the processing tank 1 can be adjusted by adjusting the pressure in the processing tank 1 by supplying steam into the processing tank 1. In the present embodiment, cooking is possible by setting the temperature freely in the range of 60 ° C to 130 ° C. In this way, the saturated steam temperature is adjusted by adjusting the pressure of the treatment tank 1.

  At the end of the heating process, the steam supply operation valve 15 is closed. At that time, if the pressure inside the treatment tank 1 exceeds atmospheric pressure, the exhaust steam operation valve 29 is opened, and drainage and steam exhaust are performed until the inside of the treatment tank 1 reaches atmospheric pressure. On the other hand, if the inside of the treatment tank 1 is less than the atmospheric pressure, the decompression means 3 and the discharge means 5 are not operated, and the steam supply operation valve 15 is closed and the return pressure operation valve 25 is opened. Restore pressure to atmospheric pressure.

  FIG. 2: is a schematic block diagram which shows Example 2 of the steam heating apparatus of this invention, and has shown the example applied to the steam cooking apparatus. The steam heating apparatus according to the second embodiment is basically configured in the same manner as the first embodiment. Therefore, in the following description, the differences between the two will be mainly described, and corresponding portions will be described with the same reference numerals.

  In the first embodiment, the control differential is changed according to the temperature target value to prevent hunting of the steam supply operation valve 15. However, in the second embodiment, instead of or in addition to this, Thus, hunting is suppressed by providing a motor valve 35 in the steam supply line 14. That is, in the second embodiment, the steam supply line 14 is connected with a motor valve 35 in series in addition to the steam supply operation valve 15 formed of an electromagnetic valve. In the illustrated example, the motor valve 35 and the steam supply operation valve 15 are provided in this order from the boiler (not shown) side, but the order of the steam supply operation valve 15 and the motor valve 35 can be interchanged.

  In the case of the second embodiment, the controller 33 controls opening / closing of the steam supply operation valve 15 and the motor valve 35 simultaneously. Although the motor valve 35 is arranged in series with the electromagnetic valve constituting the steam supply operation valve 15, the motor valve 35 is immediately opened even if an opening command is issued simultaneously to both valves 15, 35, but the motor valve 35 is opened. Due to its nature, it is opened to gradually increase the opening. By utilizing such a delay for the operation time of the motor valve 35, it is possible to prevent hunting of the steam supply operation valve 15.

  The steam heating apparatus of the present invention is not limited to the configuration of each of the above embodiments, and can be changed as appropriate. For example, in each of the above-described embodiments, the combination of the heat exchanger 18 and the vacuum pump 20 is used as the decompression unit 3, but a steam ejector, a water ejector, can cooling (cooling of a processing tank wall with cooling water), or A condensation heat exchanger or the like may be used alone or in combination. Further, after the heating step, an impregnation step or a vacuum cooling step may be performed as desired.

  Further, the hunting prevention means of the steam supply operation valve 15 when the inside of the processing tank 1 is maintained at the set pressure is not limited to the configuration of each of the above embodiments. For example, in the first embodiment, hunting of the steam supply operation valve 15 is prevented by opening / closing the steam supply operation valve 15 including a solenoid valve while making the steam supply operation valve 15 impossible to open within a predetermined time from the closing thereof. Also good. In this case, the hunting prevention means constitutes a part of the controller 33, starts a timer when the steaming operation valve 15 is closed, and opens the steaming operation valve 15 within a predetermined time. Limit. By providing a restriction on the minimum time until the steam supply operation valve 15 is once opened after being closed, hunting of the steam supply operation valve 15 can be prevented.

  Furthermore, in each said Example, although the steam supply operation valve 15 was controlled to open and close based on the detection pressure of the pressure sensor 6 so that the pressure in the processing tank 1 might be maintained at a target value, the temperature in the processing tank 1 is set as a target. The steam supply operation valve 15 may be controlled to open and close based on the temperature detected by a temperature sensor (not shown) that detects the temperature in the processing tank 1 so as to maintain the value. Or based on the detected temperature of the temperature sensor 8 which detects the temperature of the to-be-cooked item 7 so that the temperature of the to-be-cooked item 7 accommodated in the processing tank 1 may be maintained at a target value, the steam supply operation valve 15 is controlled to open and close. May be.

  Further, in each of the above-described embodiments, the steam cooking apparatus that accommodates the cooking object 7 such as food and food in the processing tank 1 and heats the cooking object has been described. Can be similarly applied to a steam sterilization apparatus which accommodates the gas in the treatment tank 1 and performs sterilization.

It is a schematic block diagram which shows Example 1 of the steam heating apparatus of this invention. It is a schematic block diagram which shows Example 2 of the steam heating apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Processing tank 2 Steaming means 3 Pressure reducing means 4 Pressure-reducing means 5 Discharge means 6 Pressure sensor 7 Object to be heated (cooking object)
8 Temperature sensor 9 Control means 14 Steaming line (steam introduction line)
15 Steaming operation valve (solenoid valve)
35 Motor valve

Claims (7)

A treatment tank in which an object to be heated is accommodated;
Steaming means for supplying steam into the treatment tank via a steaming operation valve;
Anti-hunting means for preventing hunting of the steaming operation valve when controlling the opening and closing of the steaming operation valve so as to maintain the pressure or temperature in the processing tank or the temperature of the object to be heated at a target value. A steam heating apparatus comprising: The said hunting prevention means is a means which makes the difference of the upper limit value and lower limit value differ according to the said target value about the pressure or temperature at the time of maintaining to the said target value. Steam heating device. Decompression means for decompressing the inside of the treatment tank;
Return pressure means for returning pressure in the reduced pressure treatment tank;
Discharging means for discharging steam and / or condensed water in the treatment tank to the outside;
A pressure sensor for detecting the pressure in the processing tank;
A temperature sensor for detecting the temperature of the object to be heated;
Control means for controlling opening and closing of the steaming operation valve based on a detection signal of the pressure sensor or the temperature sensor so as to maintain the pressure or temperature at the target value;
The control means determines the difference between the upper limit value and the lower limit value for the pressure or temperature when maintaining the target value, depending on which of the predetermined pressure range or temperature range the target value belongs to. The steam heating apparatus according to claim 2, further comprising the hunting prevention unit that makes the difference. The steam heating device according to claim 3, wherein the difference between the upper limit value and the lower limit value is set to be larger as the pressure or temperature becomes lower. The control means converts the temperature target value set so as to be changeable into a pressure target value, and maintains the inside of the processing tank at the pressure target value based on the detection signal of the pressure sensor. Configured to control the opening and closing of the steaming operation valve,
The hunting prevention means varies the difference between the upper limit value and the lower limit value of the pressure when maintaining the pressure target value depending on which of the predetermined temperature ranges the temperature target value belongs to. The steam heating apparatus according to claim 3 or 4, wherein the steam heating apparatus is characterized. The steam supply means includes a steam introduction pipe for supplying steam from a steam generator into the processing tank, and the steam supply operation valve including an electromagnetic valve provided in the middle of the steam introduction pipe,
The hunting prevention means includes a motor valve provided in sequence with the electromagnetic valve in the steam introduction pipe line,
The steam heating apparatus according to claim 1, wherein the electromagnetic valve and the motor valve are controlled to be opened and closed simultaneously. The steam supply means includes a steam introduction pipe for supplying steam from a steam generator into the processing tank, and the steam supply operation valve including an electromagnetic valve provided in the middle of the steam introduction pipe,
The steam heating apparatus according to claim 1, wherein the steam supply operation valve is controlled to be opened and closed while the steam supply operation valve cannot be opened within a predetermined time from the closing thereof.

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