JPS62258759A - Safety apparatus for coal crusher - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control device for a coal crusher, in particular:
This invention relates to a safety control device for detecting and controlling an impending hazardous condition within a coal crusher.

TECHNICAL BACKGROUND Coal usage in the United States of America is increasing for a variety of reasons, particularly economic reasons.

Currently, the number of coal-using vessels owned by power companies has increased by one large ton compared to 10 years ago. As the %1 of coal increases, the use of relatively young, -volatile coals such as sub-bituminous coal and lignite increases. Therefore, conveyance of coal, &
During crushing and crushing operations, the potential for spontaneous combustion, which can cause serious fires and explosions, is increased.

Previously proposed methods for detecting an imminent risk of fire within a crusher rely on measuring temperature, gas emissions, and carbon oxide levels.

Single-point or multi-point temperature monitoring methods have long been used to warn of overheating temperature conditions within mills. However, this method provides information too slowly to prevent the spread of fire. Although gas flow rate monitoring has the potential to be a powerful monitoring method, the relationship between gas flow, humidity, and pressure is not sufficiently understood to be useful as an alarm system. Increasing the level of alarming carbon within a coal crusher has received the most attention in recent research and field trials, and is one way to detect fires within the crusher.

Also, devices have been proposed that utilize infrared ridge absorption methods to monitor the level of alarming carbon within a crusher. In this method, when the coal starts to oxidize, that is, at the initial stage of combustion, a buildup of monoxide occurs.

If a very low level of alarming carbon can be detected, for example on the order of 25-50 ppm, the coal crusher operator may take precautions to prevent a large fire or explosion from occurring within the crusher. I can give a lecture.

Small pockets (clumps) of oxidizing coal cause the fire to spread (expand)
Or it may catch fire and cause a big fire. When a fire spreads, the amount of coal being burned increases, the temperature rises, and the oxidation process of the coal becomes more intense.

As the oxidation process expands, the amount of carbon produced increases, and eventually the fire spreads and a full-scale fire occurs. This small amount of oxidized coal also becomes an ignition source that can combine with other elements in the crusher to cause a large fire or explosion. In that case, only small pockets of oxidizing coal will be the source of the outbreak.
An increase in the amount of carbon monoxide does not necessarily have to occur to cause a fire or explosion. As is clear from the above explanation,
- Detection methods that rely solely on measuring carbon oxide levels are effective only when oxidation of the coal has started and cannot reliably inform the operator of the presence of an explosion risk within the crushing i. Therefore, other factors such as the level of oxygen and other combustible gases within the mill must also be considered in determining the likelihood of a fire or explosion within the mill.

In view of the above, we conducted a comprehensive measurement of zero elements, carbon oxides, and all combustible gases in the crusher, and used these measurements to control the operation of the crusher and to inform the operator of the crushing process. It is desirable to provide a safety control device 1i that is adapted to warn of the possibility of a dangerous situation occurring within the vehicle.

SUMMARY OF THE INVENTION The present invention overcomes the above-mentioned problems associated with the prior art by not relying on measurements of temperature, gas wave velocity, or carbon oxide alone to detect potential hazardous conditions within a crusher.
-Solve. The present invention utilizes a single-point ($-) point attached to the pulverizer for constant measurement of both the oxygen content and the carbon oxide equivalent level (COe) in the pulverizer's atmosphere. used) analyzer. - Measurement of carbon oxide equivalent (CO@) levels includes not only the aroused carbon level (rat) in the crusher, but also the level of combustible gases in the pond, such as hydrogen, methane, ethane. The oxygen portion of the analyzer uses a sensor that operates at the temperature at which combustible volatiles combine with oxygen in the sample exiting the mill IJ1. The sensor operates in response to residual free or unbound oxygen (net oxygen) and compares the measured net oxygen (02) level measurements therewith to various predetermined settings; and correlates carbon monoxide equivalent (CO. In this manner, measurements of both the net oxygen (0ω) level and the -carbon oxide equivalent (Coo) level within the mill are used to determine the occurrence of a hazardous condition within the mill that could lead to a fire or explosion.

DESCRIPTION OF THE EMBODIMENTS Referring to FIG. 1, the safety control system of the present invention @1
0 is used for industrial river stone back-pulverization by monitoring the net oxygen (zero) level (magnetic) and -carbon oxide equivalent (COO) levels of combustible components in the atmosphere within a coal crusher (hereinafter simply referred to as the crusher). It can be integrated into an equipment control system to monitor machine operating performance and detect impending fire or explosion hazards of the crusher. Measuring carbon monoxide equivalent (COO) levels of combustible components includes not only carbon oxide, but also other combustible components such as hydrogen, methane, ethane, and other high hydrocarbon components. Simultaneous measurements of CO and net 02 in the crusher atmosphere are used to represent the rate of coal oxidation to prevent spontaneous combustion within the crusher. Furthermore, measurements of net 02 levels, when combined with other measurements, can provide the basis for calculating the overall operating performance of the crusher and assessing the quality of the crushed coal.

As shown in FIG. 1, a CO.sub.2 sample probe (extraction tube) 12 is typically located in the exit zone of a coal crusher 14. The sample gas is extracted through a probe 12t equipped with a heat resistant filter 16. Filter 16 is necessary to maintain uninterrupted operation of controller 10 by minimizing the capping of particulate matter drawn into the analyzer.

A filter 16 that can be used for this purpose is of the type described in US Pat. No. 4.28 to 472.

The air sample extracted from the crusher 14 is supplied by a well-known w! element (02) and -carbon oxide equivalent (C
The combustible components are analyzed for volumetric oxygen (02) content and -carbon oxide equivalent (CO) in ppmm degrees using a gas analyzer. The net oxygen level, i.e., the level of free or unbound oxygen in the sample that remains after the volatiles in the sample combine with the oxygen in the sample, and - the carbon oxide equivalent (CO) level. The electrical signals representing the COe levels are respectively transmitted to the monitoring and control logic circuit unit 20 via the four markers 22.24t.The net COe level and the COe level are displayed and/or recorded on the strip recorder 26 When the net 02 level drops below a predetermined level, the device 10 activates the audible alarm 28 and visual alarm 5.
0f: Activate and notify the operator. The operator may then take a corrective action to inactivate the crusher 14 or the device 10 may initiate an auto-deactivate operating mode to bring the operating parameters of the crusher 14 back under control. Until the start, make 1 wj of fi 10! ! ◎Referring to FIG. 2, the monitoring and control logic circuit unit 20 receives the net oxygen (02) measurements supplied from the analyzer 18 through the conductor 22 and the 4z4t - Carbon monoxide equivalent (CO
Using both of the measured values of When the (0 snow) level and/or the absolute carbon oxide equivalent (CO) level reaches a certain critical value tJg, the opening degree of the valve 32 is controlled and an inert medium such as carbon dioxide or steam is introduced through the fJ154t- An automatic inactivation operation of the powder &91m14 is performed by flowing the powder into the crusher 14.

Regarding the alarm function, the constant net oxygen (Ot) 1111 value from guide 22 is transmitted through lead 36 to a comparator 38 having a set point set to a predetermined net oxygen control value, which is supplied through lead 40. Ru. Comparator 38 compares the actual net oxygen (02
) level with the set value of the net m element bell and w through the special@42 which constitutes one human power to the AND gate 44
The other input to aANDy-) 44, which provides the A difference multiple, is provided through conductor 46t- by a constant negative signal from a predetermined signal source. Thus, as long as the net oxygen (0) level supplied to the comparator 38 is higher than the net υ set value, a positive error signal is sent to the AND gate 44 through the AND gate 42t. The gate does not send any control signals through the four markers 48 and therefore does not activate the alarm 28. When the net oxygen level falls below the set point, the error signal sent through conductor 42 becomes negative and, in combination with the constant negative signal provided through conductor 46, causes AND gate 44 to conduct; This sends a control signal through the conductor NM 48 to the alarm 28, activating the alarm to notify that the atmosphere within the crusher 14 is in a dangerous condition.

A signal representative of a carbon monoxide equivalent (CO.) level measurement sent through conductor 241 activates a corresponding alarm 30. i.e. the measured carbon monoxide equivalent (COe)
The level signal is sent to the differential operation controller 50 that is sensitive to level fluctuations, and the controller 50 controls the CO in the crusher 14.
MA5 outputs an output signal representing the slope or rate of change of the t level.
Supply through 2. The output of the controller 50 is
t- to comparator 54. The comparator 54 is supplied with a predetermined COa level setpoint 56 representing the rate of change of the e level at which the coal is at risk of spontaneous combustion within the coal crusher 14 . The output of comparator 54 is
2t- is sent through conductor 58 to AND gate 60 with a constant positive value second input power supplied through lead-2t-. In operation, the rate of change of the COe level normally remains below the set point set in the comparator 54, and
A negative output signal is sent through J4 machine 58t-. The rate of change of CO@ level in the crusher is relatively 5 throughout all 56 knitting machines.
If the setting value given to 4 is exceeded, the signal sent through the knitting machine 58i becomes zero, the AND gate 60 is made conductive, the control signal is passed through the conductor 64, and is sent to the alarm 30.
/J& device is activated to indicate that there is a possibility of a dangerous situation occurring within the grinding shaft 14.

Thus, the alarms 28, 30, when activated, alert the operator of a potentially hazardous condition within the crusher 14. These alarms should alert the operator that close monitoring of the crusher 14 is required; one alarm is usually followed by a second one. Do it like this.

Since inactivating the crusher 14 will cause a shock to the crushing, it is up to the operator to decide whether or not to inactivate the crusher. However, if certain limit conditions are exceeded, deactivation of the crusher 14 is absolutely necessary and it must therefore be ensured that the deactivation operation is automatically initiated. In order to carry out the automatic inerting operation of the grinding @14, this controller [10 is connected to the net area element (02) supplied through four machines 22 and 24, respectively.
Both the measured value and the −0 carbonized carbon X equivalent (COe) measured value are utilized.

The automatic inerting operation of the crusher 14 is activated by a comparator 66 that assumes the net oxygen level setpoint supplied through the quad 68. The net oxygen level setpoint provided to ratio 'lI'D 66 is significantly lower than the setpoint provided to comparator 38. During normal operation of the mill 14, if the measured net oxygen (02) level delivered to the comparator 66 exceeds the set point supplied to the comparator, the error signal provided by the comparator 66 will be positive. The error signal of A
The signal is sent to the ND gate 72. The other power of AND gate 72 is supplied by a constant negative signal through conductor 74. Thus, during normal operation of the crusher, AND gate 72
The inputs to are positive and negative, so no control signal is transmitted from AND gate 72 through gate 76. Crusher 1
When the net oxygen (02) level in 4 drops below the setpoint supplied to comparator 66, the output of this ratio fi2 becomes negative and transmits a control signal through conductor 76 to switch 78. The on-off circuit 78 is a normally open circuit and prevents the signal from the controller 80 from reaching the control valve 32, but the
When a control signal is sent through 76vi-, the opening/closing circuit 78
is switched to a closed circuit condition, which causes controller 80 to actuate valve 32.

One input to the control mfjao is the measured net oxygen (02) level in the mill 114, which is supplied by the conductor 4M82 grafted to the '4 meter 22. The setpoint for controller 80 is supplied through knitting machine 84t from a setter (not shown) and is typically between the setpoints of comparators 66 and 38. Thus, when the open/close circuit 78 is actuated by a control signal from the AND gate 72 to indicate that the net 02 level in the crusher 14 has fallen below the set point of the comparator 66, the controller 80 opens the valve 32. , an inert atmosphere, such as carbon dioxide (COz), is sent to the mill 14 to provide a normal net oxygen level within the mill near the setting of the controller 80. Normally, the setting value of the controller 80 is the crushing amount due to the inactivation operation.
A normal atmosphere is maintained at a somewhat low level to minimize shock to 14. '& Once the net 02 level in the crusher 14 has returned to the controller 800 setting time, either by a manual signal source or by some other nozzle meter indicating that normal operating conditions have been restored within the crusher 14. The switching circuit 78 can be reset to the normally open state (by means of a reset signal provided through the conductor 86t by the No. 3 supply).

Activation of the automatic inerting means may also occur upon sensing that the absolute carbon oxide equivalent (Cot) level within the mill 14 has reached a predetermined value. 4 people 24
The carbon monoxide equivalent (COt) signal provided through
branched by a conductor 88 to provide one input to a comparator 90. The set value of the comparator 90 is determined by a setting device (not shown).
It is supplied through a dedicated pipe 92 from This setting value is usually set to pulverization tJ? Set to the maximum carbon monoxide equivalent (COO) level allowable within A14. Thus, COa
A positive error signal is sent from comparator 90 to AND gate 96 through knitting machine 94 while the error signal is less than the set point of comparator 90. The other input to AND gate 96 is conductor -9.
8 is a constant negative signal fed through 8. Thus,
During normal rotation of the crusher, signals of opposite polarity are ANDed.
Two input terminals to gate 96 prevent transmission of control signals from the AND gate through conductor 100. When the absolute CO level exceeds the set point supplied to comparator 90, the error signal transmitted to A N D gate 96 becomes negative, causing AND gate 96 to conduct and reduce the conductivity to 100.
A control signal is sent to the opening/closing circuit 78 through.

This closes the open/close circuit 78, causing the controller 80 to actuate the shutoff valve 32, as described in connection with the net zero light control. The automatic inactivation operation of the crusher 14 is performed in this manner until a reset signal is sent through mm86t-. When the reset signal is sent, the on/off circuit 78 is opened, returning the valve 32 to its normally closed position.

A fire or explosion within the crusher 14 occurs when oxygen, fuel, and an ignition source are present within the crusher. Crushing coal in a crusher produces hydrogen, methane, ethane and other combustible carbohydrates.

- Carbon dioxide is only slightly present during the grinding process (unless the oxidation process begins). When the temperature of the coal increases (when the oxidation process begins), all of the above combustible gases (hydrogen, methane, ethane, etc.) are generated and can be used as an indication of the possibility of a hazardous situation occurring. Figure 3 shows the relationship of carbon monoxide equivalent (COa) levels for each combustible gas component that makes up the carbon monoxide equivalent (CO@) in the crusher, and the general relationship between those gas levels and coal temperature. . As shown in this figure, the measurement of all these gas components as a whole (as compared to the measurement of carbon oxide alone) yields a fairly distinct response that is dependent on only one gas, namely carbon monoxide. Eliminate constraints caused by

A fire in a crusher is often preceded by a large increase in carbon monoxide equivalent (COe) levels within the crusher.

This rise is believed to be caused by oxidation of small pockets of coal within the bowl or under-bowl area. Tests have shown that such pockets of oxidized coal cannot remain in the crusher for long periods of time and have the potential to cause a fire at any time. Such pockets cannot be detected by conventional detection methods and can be detected by using the present invention, as shown in FIG. Figure 4 shows that the fire occurred after there was an increase in carbon oxide equivalent (Coe) levels - indicating the presence of smoldering coal within the crusher. That is, approximately 10 minutes after the mill starts, the carbon monoxide equivalent (COe) level increases to 250 ppm, and from an increase of 1 COe level to 3
After 0 minutes, the oxygen (02) level dropped rapidly to 5%, indicating that the temperature inside the mill was out of control and a fire had broken out inside the mill. The fire was quickly extinguished by increasing the coal supply, but sparks observed from the underbowl area verified that the fire was occurring and that the coal was still smoldering. It was done. Thereafter, the -carbon oxide equivalent (COe) level gradually decreased to about 55 ppm over a period of 7 hours. This indicates that the smoldering coal was gradually burnt out, during which time a second fire could occur as indicated by the high -Cm carbon equivalent (Cog) levels.

An example of a short-lived fire in a crusher that did not reach full-blown fire is shown in Figure 5. As shown in Figure 5, approximately 30 minutes after the mill was started, the COO level increased from 35 ppm to 225 ppm and remained at that high level), and the net level increased from 17.75% to 1.
The value decreased to 6.75%.

Afterwards, when the inside of the pulverizer was inspected and the COe and O snowflakes returned to normal levels, a small amount of coal was found.
It was found that it had been smoldering in the crusher for 0 minutes. The amount of smoldering coal was not large enough to cause a fire in the crushed circle.

It is clear from the above description that: 5. provides an improved method for early detection of possible hazardous situation occurrence in a crusher by monitoring the COO level in the crusher; Necessary corrective measures to avoid a fire or explosion on board the aircraft can be discussed. Such early detection
This was not possible using conventional detection methods.

FIG. 6 shows the general relationship between COO level, net 02 level and conditions within the crusher. Normal operation band (band)
indicates the COO level, the net 02 level, and the type of coal used. The higher the percentage of volatile substances in the coal, the higher the CO level. Also, the higher the moisture content (%) of the coal, the higher the moisture level in the gas in the crusher and therefore the lower the net 02 level. Q)e
If the level increases and the net 02 level remains unchanged or decreases, this indicates that a scumJ:j1) condition exists in the crusher, and there is a risk of a fire occurring.

Also, CO! Elevated levels indicate that the crusher is at risk of explosion. From the above description, it will be understood that detecting and measuring the CO8 level together with the net 02 level has an important meaning in determining the possibility of a hazardous situation occurring within the crusher.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the safety control device of the present invention, and Fig. 2 is a schematic diagram of the safety control device of the present invention.
A schematic diagram of the monitoring and open operation logic circuit unit of the device shown in FIG.
Figure 3 is a graph showing the relationship between various combustible components, COO level and net 02 level, and the relationship between those levels and coal temperature, and Figure 4 is a graph showing the relationship between COβ level and net 02 level in the crusher. Figure 3 is a graph showing the relationship between levels and time, showing the change in these levels when a fire occurs in a multi-grinder. Figure 5 shows the C0 inside the crusher.
Graph showing the relationship between g level and net 02 level versus time, showing the change in those levels when smoldering is present in the crusher but does not lead to a fire. FIG. 6 is a graph of net 02 levels versus CO+e levels in the mill, illustrating the manner in which the operating conditions of the mill depend on those levels. 10: Safety control device 12: Sample probe 142 Coal crusher 18: Gas analysis number 208 Monitoring and control circuit unit 28.30: V
k@ device 32: control valve 38.54.66.90: comparator 44.60.72.96: AND gate 78 two opening/closing circuits 80: controller: f5); 1tJ (2 o'clock FIG, 1 0 switch 4 ♀Nishinoishiroku FIG, 3 FIG, 4 1'i/2'f 小(-”] QA';19 and C○e+
02 ”-The thickest part,

Claims (1)

Claims: 1) A safety device for a coal crusher that measures the rate of change in the level of carbon monoxide and other combustible gases within the coal crusher and provides a signal representative of the rate of change. measuring means for determining a first control signal by comparing the signal from the measuring means with a predetermined setpoint signal representative of a dangerous rate of change in the level of carbon monoxide and other combustible gases in the coal crusher; a comparator for emitting a signal; and an alarm for indicating a possible occurrence of a hazardous condition within the coal crusher in response to the first signal. 2) measuring means for measuring the level of carbon monoxide and other combustible gases in the coal crusher, and connected to the measuring means, the level of carbon monoxide and other combustible gases in the coal crusher; 2. The safety device of claim 1, further comprising a differential motion controller for producing an output signal representative of the rate of change of the safety device. 3) measuring means for measuring the level of net oxygen within the coal crusher and emitting a signal representative of the level; and a signal from the net oxygen level measuring means and a dangerous level of net oxygen within the coal crusher. and a comparator for generating a second control signal by comparing the signal with a first predetermined set value signal representing the value of the signal, the alarm being adapted to also respond to the second control signal. The safety device described in paragraph 1. 4) a comparator for comparing the signal from the net oxygen level measuring means and a second predetermined setpoint signal representative of a critical level of net oxygen within the coal crusher to generate a third control signal; 4. A safety device according to claim 3, further comprising deactivation means for deactivating the inside of said coal crusher in response to a third control signal. 5) The inerting means is responsive to the third control signal, including: an inerting atmosphere source for inerting the inside of the coal crusher; a valve device for controlling the inerting atmosphere source; 5. The safety device according to claim 4, further comprising control means for controlling the valve device. 6) An opening/closing means connected between the control means and the valve device for controlling the valve device via the control means in response to the third control signal. Safety devices described in scope item 5. 7) A safety device for a coal crusher, which measures the level of carbon monoxide and other combustible gases in the coal crusher;
measuring means for emitting a signal representative of said level; and comparing the signal from said measuring means with a predetermined set point signal representative of a dangerous level of carbon monoxide and other combustible gases in said coal crusher. A safety device comprising: a comparator for issuing a first control signal; and deactivation means for deactivating the interior of the coal crusher in response to the first control signal. 8) The inactivation means includes: an inert atmosphere source for inactivating the inside of the coal crusher; a valve device for controlling the inert atmosphere source; and a first control from the comparator. Claim 7 comprising control means for controlling the valve arrangement in response to a signal.
Safety devices listed in section. 9) measuring means for measuring the level of net oxygen in the coal crusher and emitting a signal representative of the level; and a signal from the net oxygen level measuring means and a dangerous level of net oxygen in the coal crusher. a comparator for generating a second control signal by comparing the signal with a first predetermined set point signal representing the coal crusher; and an alarm for indicating the possibility of a hazardous condition occurring within the coal crusher in response to the second signal. The safety device according to claim 8, comprising: 10) a signal from said net oxygen level measuring means and said first
a comparator for generating a third control signal by comparing a second predetermined set value signal lower than the predetermined set value signal, and the control means controls the valve device in response to the third control signal as well. A safety device according to claim 9, which is configured as follows. 11) opening/closing means connected between said control means and said valve arrangement, said opening/closing means controlling dangerous levels of carbon monoxide and other combustible gases in said coal crusher with a predetermined set point signal; the control means for activating the valve arrangement in response to a control signal from the comparator that compares or a control signal from the comparator that compares a critical level of net oxygen within the coal crusher to a second predetermined set point signal; 11. The safety device according to claim 10, wherein the safety device is controlled via a. 12) A safety device for a coal crusher, comprising: measuring means for measuring the level of net oxygen within said coal crusher and emitting a signal representative of said level; and carbon monoxide and others within said coal crusher. measuring means for measuring the rate of change in the level of the combustible gas and emitting a signal representative of the rate of change; and comparing the signals from the two measuring means with respective corresponding predetermined setpoint signals; a comparator for issuing respective independent control signals when the signals from the measuring means exceed respective predetermined set signal values; and a hazardous condition within the coal crusher in response to said respective independent control signals. A safety device consisting of an alarm to indicate the possibility of an occurrence.