JPH031487Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a fire prevention device for a conveying duct that uses airflow to convey raw cotton, etc. separated into fibers.
In detail, depending on the occurrence of sparks that can cause a fire, it is possible to improve the operating rate of transport ducts and prevent fires by selectively operating fire prevention shutters or taking measures to prevent ignition, such as introducing cold air. At the same time, the certainty of

BACKGROUND TECHNOLOGY In the mixed batting process at a spinning factory, raw cotton is separated into fibers and impurities such as pebbles are removed while the fibers are fed under pressure using an air stream.

This separation and conveyance is carried out by separating raw cotton into fibers and feeding them under pressure through a cotton feeding duct 1 using a fan 2, as shown in FIG.
Pebbles and the like are separated into the dust collection duct 4 by utilizing the difference in weight. Further, the plurality of dust collecting ducts 4 are connected to an underground pit (not shown) in which the dust is transported by wind pressure.

In such transport ducts such as the cotton transport duct 1, separation duct 3, dust collection duct 4, and underground pit, pebbles contained in the fibrous raw cotton transported at high speed hit the walls at high speed, causing sparks. Occur.
The raw cotton being transported is separated into fibers, spread uniformly within the duct, and moves along with the airflow, making it extremely susceptible to ignition. For this reason, if a spark is generated, it is easy to cause a fire, and once a fire occurs, the raw cotton is carried by high-speed air currents at speeds of more than 10 meters per second, causing great damage as the fire spreads. Therefore, spark detectors 5 using optical sensors are installed at several locations on the wall of the duct, and when the occurrence of sparks is detected, the shutters 6 that partition the conveyance duct are closed at high speed to prevent the spread of fire.

Problems to be Solved by the Invention In the conventional fire spread prevention system described above, when a spark is detected by a spark detector, the heavy shutter is immediately lowered by its own weight.

In this way, it is preferable to divide the transport duct with shutters at the same time as spark detection to prevent the spread of fire, from the viewpoint of increasing safety.

However, the generation of a spark does not immediately lead to a fire; even if a spark is generated, it may not ignite, or even if it ignites, it may spontaneously extinguish.

If the shutter is lowered in such a case, the operating rate of the equipment will drop significantly. In other words, since the shutter is heavy, it takes time and effort to pull it back up to its original position to resume operation. Furthermore, if the shutter falls, it is assumed that a fire has occurred and the burnt raw cotton must be removed, so all the raw cotton sent through the transport duct must be manually inspected, making recovery work very time consuming.

For this reason, it may be possible to adjust the sensitivity of the spark detector so that the shutter operates only when a fire occurs.

However, this adjustment is practically impossible. As shown in FIG. 3, the equal sensitivity curve of the spark detector spreads radially from the high sensitivity region A to the low sensitivity region B, and it is not possible to detect sparks within the conveying duct with the same sensitivity. That is, even if it is set to detect a large spark F that could lead to a fire in a low-sensitivity area B and not to detect a small spark f that could lead to a fire, a small spark F will still be detected in a high-sensitivity area A.

Furthermore, even if a small spark f occurs in the low sensitivity region B, it cannot be detected. Furthermore, it is not possible to understand the stages before a fire occurs in the transport duct.

For this reason, countermeasures such as introducing cold air cannot be taken, causing problems in management.

Therefore, the present invention was designed to avoid large sparks that can easily cause a fire.
It is an object of the present invention to provide a device that distinguishes and detects a small spark f and a small spark f, and outputs each of them separately.

Means for Solving the Problems The fire prevention device for a conveying duct provided by the present invention is a conveying duct that is equipped with a fireproof shutter at a predetermined position and that uses an optical sensor to forcefully convey microscopic objects such as fibrous raw cotton using an air flow. and a plurality of spark detectors having an amplifier and installed on the wall of the conveying duct and generating an output signal when a spark is detected, and generating a fire prevention signal when any one of the spark detectors outputs, The present invention is characterized in that it includes a logic gate that generates a fire protection shutter closing signal when a predetermined number or more of spark detectors output simultaneously.

Operation In the fire prevention device configured as described above, each of the low-sensitivity low-detection areas of each spark detector detects almost the entire portion that crosses the conveyance duct, and the high-sensitivity detection area of each spark detector detects approximately the entire portion that crosses the conveyance duct. The sensitivity is adjusted so that substantially the entire portion crossing the conveyance duct is divided and detected.

Therefore, large sparks that can easily cause a fire can occur at any point across the conveying duct.
If this occurs, two or more spark detectors will output. Further, when a small spark f occurs, one of the spark detectors detects this in its highly sensitive detection area and outputs it.

The logic gate outputs a shutter close signal to prevent the spread of fire when two or more spark detectors output, and when any one spark detector outputs, it generates a fire prevention signal and cools the gate. Enables introduction of air, etc.

Therefore, the shutter is operated only in the minimum necessary cases, and even small sparks can be reliably detected.

Example The present invention will be described with reference to one embodiment.

In FIG. 1, reference numeral 9 denotes a conveying duct, through which raw cotton, etc. separated into fibers is conveyed under pressure on an air flow. This conveyance duct 9 is a general term for the aforementioned cotton conveyance duct 1, separation duct 3, dust collection duct 4, underground pit, etc.

Reference numerals 10, 10, . . . indicate spark detectors, which are installed at positions that equally divide the circumference of the wall surface of the conveyance duct 9 into four.

These spark detectors 10, 10... are connected to the conveying duct 9.
a light-receiving element 10b such as a photodiode that receives the light inside through the lens 10a; an amplifier section 10c that outputs a spark detection signal when the output of the light-receiving element exceeds a predetermined reference level; and a sensitivity that adjusts this reference level. It is equipped with a regulator 10d. By adjusting this sensitivity adjuster 10d, each spark detector 10, 10... detects a small spark f only in a narrow high sensitivity area A, and a large spark F in a wider low sensitivity area B. If so, it will be detected.

11 is a logic gate consisting of an OR circuit 11a and a redundant output circuit 11b. The OR circuit 11a outputs a fire prevention signal P when any one of the ignition detectors 10, 10, . . . outputs an output. The duplicate output detection circuit 11b is composed of AND gates 12, 12, . . . and an OR gate 13, and outputs a shutter close signal S when any two of the spark detectors 10, 10, . Note that once the fire prevention signal P is generated, it is stored in the self-holding circuit 14, and is output as an external output signal O at the same time as the alarm means 15 such as a buzzer or indicator light is activated. Therefore, once the fire prevention signal P is generated, the alarm state continues unless the operator presses the reset switch 14a of the self-holding circuit 14 after taking the prescribed measures.

In the fire prevention signal 16 of the transport duct,
When a large spark F that easily causes a fire is generated, it is detected even in the low sensitivity region B of the spark detectors 10, 10, etc., so two or more spark detection outputs are generated, and the shutter close signal is output from the logic gate 11. S and fire prevention signal P are output. This closes the shutter and generates an alarm. Further, when a small spark f occurs, it is rare that two or more spark detection outputs are generated, and usually only the fire prevention signal P is generated, and an alarm is activated and an external output signal O is output. This external output signal O can be used as.

Note that two or more spark detectors 10, 10, . . . may be provided as a pair, and the output condition for the shutter closing signal P may be that three or more spark detection signals are generated simultaneously.

Effects of the invention The present invention uses a spark detector to prevent fires by using two-stage spark detection conditions, and at the same time minimizes the shutter closing operation to the necessary minimum, it also warns of the occurrence of small sparks. Therefore, it is possible to improve the operating rate and reduce production costs while ensuring prevention of spark generation and fire spread.

[Brief explanation of the drawing]

FIG. 1 shows an embodiment of the present invention, and is a diagram showing a circuit configuration in which a spark detector is attached to a conveying duct and a shutter closing signal S and a fire prevention signal P are extracted from the output thereof. FIG. 2 is a sectional view showing an example of the structure of the conveyance duct. FIG. 3 is an example of a characteristic diagram of detection sensitivity of a spark detector. 9... Conveyance duct, 10... Spark detector, 11... Logic gate, 16... Fire prevention device for conveyance duct.

Claims (1)

[Scope of Claim for Utility Model Registration] A conveyance duct that is provided with a fireproof shutter at a predetermined position and that uses airflow to convey microscopic objects such as fibrous raw cotton, which is equipped with an optical sensor and an amplifier, and is attached to the wall of the conveyance duct. a plurality of spark detectors that generate an output signal when detecting a spark; and a fire prevention signal that generates a flame prevention signal when any one of the spark detectors outputs a fire prevention signal, and a fire prevention shutter when a predetermined number or more of the spark detectors output simultaneously. A fire prevention device for a conveyance duct, comprising a logic gate that generates a closing signal.