JPH09257544A - Level detecting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect the level without concerning the solidification inside of pipeline and conduit. SOLUTION: A container for housing the liquid or the material to be liquidized by heating and a heating means for heating this container from outside are provided. Multiple wall temperature detecting sensors KN arranged in a wall surface of the container in the vertical direction with the predetermined pitch and a liquid temperature detecting sensor Ko for detecting liquid temperature inside of the container 1 and a level judging means for searching a non- continuous part of temperature difference between each wall temperature sensor KN and the liquid temperature detecting sensor, Ko and for judging the level inside of the container on the basis of the search are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level detecting device in a device provided with a container into which a liquid or a substance to be liquefied by heating is put, and a heating means for heating the container from the outside.

[0002]

In this type of liquid level detection device, the substance to be put into the container is solid at room temperature, and a stirrer is generally installed in the container. There are a method of detecting with a load cell (method of detecting with a load) and a method of taking out with a pipe to the outside and detecting. However, it is difficult to remove the influence of the load of the pipes connected to the container by the former method,
Further, in the latter method, it was necessary to heat the connecting pipe and the chamber to make them liquid, and it was necessary to control the temperature thereof.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and a container for containing a liquid or a substance to be liquefied by heating, and a heating device for externally heating the container. And a plurality of wall temperature detection sensors arranged vertically on the wall surface of the container at a predetermined pitch, a liquid temperature detection sensor for detecting a liquid temperature in the container, and each wall temperature detection sensor. A liquid level determination means for determining a discontinuous portion of the temperature difference between the liquid temperature detection sensor and the liquid temperature detection sensor, and determining the liquid level in the container based on the search result.
And the

Further, in the liquid level detecting apparatus according to the first aspect, the heating means can take a heating state in which hot gas is supplied to heat the container and a scavenging state in which hot gas is not supplied, and the liquid level determination is performed. A second feature is that the means collates the sensor search result in the heating state with the sensor search result in the scavenging state,

Further, in a container provided with a container for containing a liquid or a substance to be liquefied by heating, and a heating means for heating the container from the outside, a large number of containers are vertically arranged on the wall surface of the container at a predetermined pitch. Of the wall temperature detection sensor, the temperature difference between the wall temperature detection sensor adjacent to each wall temperature detection sensor, or search for a discontinuous portion of the temperature difference between each wall temperature detection sensor and a specific wall temperature detection sensor, A third feature is that the liquid level determination means for determining the liquid level in the container based on the search result is provided.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As an embodiment of a liquid level detecting device corresponding to claim 1 of the present invention, a container for containing a liquid or a substance to be liquefied by heating, and a heating for heating the container from the outside. And a plurality of wall temperature detection sensors arranged vertically on the wall surface of the container at a predetermined pitch, a liquid temperature detection sensor for detecting a liquid temperature in the container, and each wall temperature detection sensor. And a liquid temperature detection sensor for searching a discontinuous portion of the temperature difference between the liquid temperature detection sensor and the liquid temperature detection sensor, and liquid level determination means for determining the liquid level in the container based on the search result.

This embodiment will be described in detail below. The liquid or the substance to be liquefied by heating is a plastic or animal oil having a high pour point that is liquefied by heating in a solid state at room temperature, but may be a substance that is liquid at room temperature. The container containing this substance is usually made of metal and is heated from the outside by a heating means such as a combustion device. As a heating means, a combustion device for generating hot gas (high temperature gas) or a container is provided as a double structure of an inner container and an outer container for containing a substance to supply a high-temperature heat medium between the inner container and the outer container. The heating means may be configured to heat the substance in the inner container. As the combustion device, a device that burns a gaseous fuel, a device that burns a liquid fuel, or the like is adopted. The wall temperature detection sensor is directly attached to the outer wall of the container to directly detect the outer wall temperature, or the outer wall temperature of the container is detected by interposing a member with the outer wall, or the wall temperature detection sensor is attached to the inner wall of the container. The temperature is detected, and for example, a thermocouple or a resistance temperature detector (such as a thermistor) is used. A large number of the wall temperature detecting sensors are vertically arranged on the wall surface of the container at a predetermined pitch (for example, several mm pitch) at equal intervals or unequal intervals. The large number is a number by which a change in temperature difference, which will be described later, can be determined, and the number is determined by the fluctuation range of the liquid surface. The liquid temperature detection sensor is inserted at a position that can always detect the liquid level in consideration of the liquid level fluctuation in the container.
Is used.

Further, the liquid surface determination means calculates the temperature difference between each wall temperature detection sensor and the liquid temperature detection sensor, and the portion where the difference is discontinuous, in other words, the portion where the difference greatly changes (wall temperature The sensor) is searched, and the liquid level is determined based on the search result. The determination that the temperature difference is discontinuous is determined to be large when the absolute value of the temperature difference is equal to or greater than a predetermined value (determination by absolute value comparison), or the temperature difference of a certain wall temperature sensor and another wall temperature sensor. A method of making a judgment (judgment by relative comparison) based on a difference or a ratio with the temperature difference of is used. By determining that this temperature difference is discontinuous, a sensor close to the liquid level can be specified and searched, and the liquid level in the container is estimated based on the search result. In the present embodiment, even when the heating means can take the heating state and the scavenging state, the liquid level may be determined in either one of the states.

Next, as an embodiment corresponding to claim 2 of the present invention, in the liquid level detecting device according to claim 1 or 2, a heating state in which the heating means supplies hot gas to heat the container. And a scavenging state in which hot gas is not supplied can be taken, and the liquid level determination means collates the sensor search result in the heated state with the sensor search result in the scavenged state.

To explain this embodiment, in addition to the embodiment of claim 1, it is possible to adopt a heating state in which the heating means supplies the hot gas to heat the container and a scavenging state in which the hot gas is not supplied. In that case, in the heated state, saturated vapor exists in the upper part of the liquid level in the container, so heat transfer from the outside is not sufficient, and the relationship of the temperature of the liquid layer portion <the temperature of the vapor phase portion is established. On the other hand, since heating is not performed in the scavenging state, liquefaction proceeds in the vapor phase portion, and heat of condensation is released at that time, and as a result, a liquid film is formed, and the temperature of the liquid layer portion> vapor phase portion Based on the knowledge that the temperature relationship of is established, the liquid level is determined by the liquid level determination means both at the time of heating and at the time of scavenging, and the determination results of both are compared and collated to determine the liquid level. It is exactly what you do. Whether it is the scavenging state or the heating state can be determined by monitoring the control signal in the control means for controlling the heating means. Further, in the present embodiment, desirably, when the temperature difference between the sensors is the temperature of the liquid layer portion <the temperature of the vapor phase portion in the heating state, it is determined that the temperature is correctly detected, and the scavenging state is established. When the temperature difference between the sensors is such that the temperature of the liquid layer portion> the temperature of the vapor phase portion, a means for determining that the temperature is correctly detected is provided, and if not, based on the result of the temperature difference calculation. Processing such as not performing liquid level determination is performed. The scavenging state means scavenging before the start of combustion (so-called pre-purge) or scavenging after the combustion is stopped (so-called post-purge) when the heating means is a combustion device, and the heating state means combustion of the combustion device. To do. Further, in the stop state in which neither combustion nor scavenging is performed, the liquid level determination by the liquid level determination means is not performed, and the liquid level determination result in the heating or scavenging state is held and may be output. good.

Next, as an embodiment of a liquid level detecting device according to claim 3 of the present invention, a container for containing a liquid or a substance to be liquefied by heating, and a heating means for heating the container from the outside. And a plurality of wall temperature detection sensors arranged vertically at a predetermined pitch on the wall surface of the container, and a temperature difference between the wall temperature detection sensors adjacent to each wall temperature detection sensor, or each wall temperature detection sensor. It is assumed that the apparatus is provided with a liquid level determination unit that searches a discontinuous portion of the temperature difference between the detection sensor and the specific wall temperature detection sensor and determines the liquid level in the container based on the search result.

This embodiment will be described in detail below. The difference of the present embodiment from the embodiment of claim 1 is that the liquid level is determined only by the wall temperature detection sensor, not by the liquid temperature detection sensor. That is, the liquid surface determination means of this embodiment searches for a portion where the temperature difference is discontinuous by the following temperature difference calculation means. First, by a temperature difference calculating means for calculating a temperature difference between each wall temperature detecting sensor and an adjacent wall temperature detecting sensor, or by a specific wall temperature detecting sensor, for example, a sensor for detecting the wall temperature of a portion which is always a liquid layer. A specific wall temperature detection sensor is used, and temperature difference calculation means for calculating the temperature difference between this sensor and each of the other wall temperature sensors. For the calculation of the temperature difference between each wall temperature detection sensor and the adjacent wall temperature detection sensor in the former temperature difference calculation means, for example, the temperature difference between the adjacent sensors is sequentially calculated from the bottom wall temperature sensor, The calculated value is stored in the memory, and a sensor that has a large change in the calculated value and becomes discontinuous is searched for and specified. In this case, the sensors are multiple adjacent sensors, but it is decided in advance which of the upper sensor or the lower sensor is to be the specific sensor, and the liquid level is the mounting position of either sensor. May be determined, or the space between the plurality of searched sensors may be determined to be the liquid surface. When the latter temperature difference calculating means for calculating the temperature difference between the specific wall temperature detecting sensor and each of the other wall temperature sensors is used, the searching method can be the same as that of the embodiment of claim 1.

In each of the above embodiments, the following means are preferably provided. First, it is desirable to provide a stirring means for stirring the liquefied substance in the container. This stirring means is for equalizing the temperature in the liquid layer portion inside the container, and for example, a stirring blade for mechanical stirring, or a circulation path is formed outside the container for the substance, and this circulation path is used. Circulating stirring means is used. Further, it is desirable to provide a pour point detecting means for detecting that the temperature of the substance in the container is equal to or higher than the pour point. By limiting the liquid level determination after the substance has fluidized, it is possible to prevent unnecessary liquid level determination. When the pour point detecting means is not used, the liquid level determination may be started after heating for a predetermined time by the heating means. Further, it is preferable to include an arithmetic means for obtaining an initial liquid level position from the amount of the substance put into the container and an initial liquid level determining means for determining whether the initial determination by the liquid level determining means is appropriate. This makes it possible to verify the validity of the determination made by the liquid surface determination means.

[0014]

EXAMPLE An example corresponding to the first and third embodiments of the plastic decomposing device in which the heating means is a combustion device will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 1 denotes a container for disassembling (melting and vaporizing) a plastic decomposing device for melting and vaporizing plastic (synthetic resin) by heating, which is usually made of steel. The container 1 is heated from the outside by hot gas (in this case, combustion gas) generated when the combustion device 2 burns. The combustion device 2 is controlled to any one of a scavenging state, a heating (combustion) state, and a non-operating stop state by a control signal output from a controller 3 including a microcomputer.

K ₁ , K ₂ , K ₃ ... K _N (N is a positive integer) are attached to the outer wall of the container 1 so as to detect the wall temperature of the container 1 at a predetermined pitch of several millimeters vertically. Thermocouples are used as sensors in many of the wall temperature detection sensors described above. K
Reference numeral ₀ denotes a liquid temperature detection sensor that is inserted in the container so as to constantly detect the temperature of the liquid layer portion L in the container 1, and is located below the lower limit of the expected liquid level fluctuation range in the container 1. The thermocouple is used as a sensor. Reference numeral 4 is a stirring blade for stirring the liquid layer portion L in the container 1, which is a driving means (not shown).
Is driven to rotate. The controller 3 inputs signals from the wall temperature detection sensors K ₁ ... K _N and the liquid temperature detection sensor K ₀ , and controls the combustion device 2 and the like according to a processing procedure stored in advance in a memory (not shown). At the same time, the liquid level position in the container 1 is determined and the result is displayed on the display unit 5.
FIG. 3 shows an example of a processing procedure for liquid level determination by the controller 3.

The control configuration and operation of the controller 3 of this embodiment will be described below with reference to FIG. In step S1 (hereinafter, S∘ means step S∘), the plastic in a solid state at room temperature is charged into the container 1, the heating device 2 is heated, and the stirring blade 4 is driven after the plastic is fluidized. Start disassembling the plastic. Next, in S2, it is determined whether the temperature detected by the liquid temperature detection sensor K ₀ is equal to or higher than the pour point T _X. If NO, repeat S1 → S2, YE
S is determined, that is plastic flow of the container 1, when it is possible to determine the liquid level, of each wall temperature sensor K ₁ · · · K _N proceeds to step S3 detected temperature T ₁ · · · T _N The temperature difference T _N -T ₀ between the temperature detected by each wall temperature sensor and the temperature detected by the liquid temperature sensor is calculated and stored in the memory. Next, in S4, it is determined whether the combustion device 2 is heating, scavenging, or otherwise (stopped). When it is determined that heating is in progress, the process proceeds to S6, and when T _N -T ₀ is positive, that is, when the wall temperature of the container 1 is determined to be higher than the liquid temperature, it is determined that the temperature detection is normal, and the process proceeds to S5. To do. If all of the results are not positive in the determination in S5, it is determined in advance whether to make a majority decision or an abnormality. Next, in S6, the temperature difference T _N −
A search is made for T ₀ to find a portion where the value is large and discontinuous, that is, a portion which is larger than a predetermined value previously obtained by experiments or the like. For example, assuming that the temperature difference below the liquid surface is about 20 ° C, but about 30 ° C in the vapor phase portion near the liquid surface, the predetermined value is set to 25 ° C, and the sensor with the temperature difference 30 is It is determined that the temperature difference is large, and the sensor is specified as the sensor near the liquid surface. Then, the process proceeds to S9 to determine and output the liquid level. That is, if it is assumed that the identification of the sensor in S5 is the first, the position of the identification sensor is set as the liquid level,
Output to the display unit 5 and return to S1. The display unit 5 displays the position of the liquid surface numerically or pictorially.

When it is determined in S4 that the scavenging is in progress, the process proceeds to S7, and when it is determined that T _N -T ₀ is negative, that is, the wall temperature of the container 1 is lower than the liquid temperature, it is determined that the temperature detection is normal. Then, the process proceeds to S7. In addition, when all are not negative in the determination of S7,
It is determined in advance whether to make a decision based on a majority decision or an abnormality. Next, in S8, the temperature difference T _N -T ₀ is searched, and a portion where the value is large and discontinuous, that is, a portion where the value is smaller than a predetermined value previously obtained by experiments or the like is searched. For example, if the temperature difference is −15 degrees C below the liquid surface, but −30 degrees C in the gas phase near the liquid surface, the temperature difference is −3 degrees.
A sensor at 0 degrees C is specified as a sensor near the liquid surface. When the process of S8 is completed, the process proceeds to S9. Here, if the sensor of the liquid surface part being heated is specified, this specific sensor being heated is compared with the specific sensor being scavenged this time, that is, whether both sensors are the same, It is determined whether the distance between the inside sensor and the scavenging sensor is within a predetermined range. When this determination is YES, the liquid level determination is determined to be normal, and the previous display is displayed on the display unit 5.

It should be noted that, in FIG. 3 of the present embodiment, the processes S6 and S8 may be integrated into one and may be arranged after the process S3.

Next, an example corresponding to the embodiment of claim 3 will be described with reference to FIG. In FIG. 4, FIG.
3 is different from the temperature difference T _N -T _{0 in} the embodiment of FIG. 3, but is T _N -T _N-1 , that is, the adjacent wall temperature sensor K _N and the wall temperature sensor K _{N. The} difference is that the detected temperature difference from _-1 is sequentially calculated, and the liquid level is determined based on the result. This embodiment will be described in detail below with reference to FIG.

Since steps S1 and S2 are the same as those in FIG. 3, they are omitted. In S3, each wall temperature sensor K ₁ ...
The detected temperature T ₁ ... T _N of K _N is taken in, and the detected temperature difference T _N -T _{N- of} each adjacent wall temperature sensor, such as T ₂ -T ₁ , T ₃ -T ₂ ... Calculate ₁ and store in memory. Next, in S4, the temperature difference T _N -T _N-1 is searched, and a discontinuous portion whose value greatly changes, that is, becomes smaller or smaller than a predetermined value previously obtained by experiments or the like, is searched, and the temperature difference T _N -T _N-1 shown in FIG. Similar to the embodiment, a sensor having a discontinuous temperature difference is specified as a sensor near the liquid surface. Then
The process proceeds to S5, and the liquid level is determined and output. That is, if it is assumed that the identification of the sensor in S5 is the first one, the position of the identified sensor is used as the liquid level and is output to the display unit 5, and the process returns to S1. The display unit 5 displays the position of the liquid surface numerically or pictorially.

The process in S5 is performed regardless of whether heating, scavenging, or stopping is performed, and the sensor position during heating is compared with the sensor position during scavenging, that is, whether or not both sensors are the same, or during heating. It is determined whether or not the distance between the sensor and the sensor being scavenged is within a predetermined range. When this determination is YES, the liquid level determination is determined to be normal, and the previous display is displayed on the display unit 5.

[0022]

According to the present invention configured as described above, the liquid level can be determined and detected without worrying about solidification in the pipes and conduits, and the liquid level detection device can be configured simply and inexpensively. There is an effect that can be done.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a plastic disassembling apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing an electrical schematic configuration of the embodiment of the present invention.

FIG. 3 is a flowchart showing a control procedure by the controller according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a control procedure by a controller according to another embodiment of the present invention.

[Explanation of symbols]

1 Container 2 Combustion Device (Heating Means) 3 Controller 5 Display K _N Wall Temperature Detection Sensor K ₀ Liquid Temperature Detection Sensor

Claims (3)

[Claims] 1. A container comprising a container for containing a liquid or a substance that is liquefied by heating, and a heating means for heating the container from the outside. A large number of containers are arranged vertically on a wall surface of the container at a predetermined pitch. Of the wall temperature detection sensor, a liquid temperature detection sensor for detecting the liquid temperature in the container, a non-continuous portion of the temperature difference between each wall temperature detection sensor and the liquid temperature detection sensor, and based on this search result A liquid level detection device comprising: a liquid level determination means for determining the liquid level in the container. 2. The liquid level detection device according to claim 1, wherein the heating means can be in a heating state in which the heating gas is supplied to heat the container and a scavenging state in which the heating gas is not supplied, and the liquid level determination is performed. A liquid level detection device, wherein the means collates the sensor search result in the heating state with the sensor search result in the scavenging state. 3. A container comprising a container for containing a liquid or a substance to be liquefied by heating and a heating means for heating the container from the outside, and a large number of the containers are vertically arranged on a wall surface of the container at a predetermined pitch. Of the wall temperature detection sensor, the temperature difference between the wall temperature detection sensor adjacent to each wall temperature detection sensor, or search for a discontinuous portion of the temperature difference between each wall temperature detection sensor and a specific wall temperature detection sensor, A liquid level detection device comprising: a liquid level determination means for determining the liquid level in the container based on the search result.