JPS6311044B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter dust removal device for a dust collector that automatically and efficiently removes dust adhering to a filter during dust collection operation.

An important point in the operation of a dust collector is the dust removal effect of the filter, and whether or not the dust collector can operate stably is directly influenced by the quality of the dust removal effect.
Conventional dust removal devices that perform this dust removal work include pulse jet type, backwash type, and vibration type. This prevents the filter from clogging. Also, the point to check the dust removal effectiveness of these devices is the pressure loss of the filter.
Usually expressed as △P (mmAg),
Among the above-mentioned devices, the pulse jet dust removal device in particular has an excellent dust removal effect and has the advantage of being able to perform stable dust collection operation at a certain point with a small fluctuation range of △P. The description of the prior art will be made by conveniently selecting the above-mentioned typical pulse jet type dust removal device.

In other words, a pulse jet dust removal device is a device that blows out compressed air against the filters to remove dust attached to the filters.After removing dust from several filters in one row at the same time,
The structure is such that dust is removed from the filters in the next row at regular intervals. This dust removal interval is usually set by a timer, but if the interval is too long, the pressure loss of the filter will increase and the air volume will decrease.
On the other hand, if the length is too short, compressed air will be wasted, and problems will occur, such as shortening the life of the filter and making it easier for dust to leak. In order to operate the dust collector in a stable condition, this dust removal interval must be determined to be the most favorable condition, but this dust removal interval depends on many factors such as the type of dust, particle size, and dust concentration. Because they differ, it was a hassle to have to adjust the timer many times to determine the best interval when installing the dust collector. In addition, since the amount of dust being sucked is not constant but constantly changing, there was a problem in that when the amount of dust fluctuated greatly, it was necessary to change the setting time of the timer each time. Incidentally, Figure 5 shows the relationship between on-time (pulse generation time, that is, air jetting time) and off-time (dust removal interval) in a conventional pulse-jet type dust remover, and on-time A is usually the capacity of the dust collector. An appropriate time (for example, 0.04/sec) is preset at the time of shipment as a standard value, and the off time B can be freely adjusted by operating a timer. It goes without saying that the above-mentioned problems also occur in backwash type and vibration type dust removal devices.

In view of the above-mentioned points, the present invention detects the pressure difference before and after the filter, that is, the pressure loss ΔP of the filter, and automatically adjusts the off-time interval of the dust removal operation part to a longer or shorter time depending on the amount of the detected pressure difference. In addition, by sequentially adding and controlling the shortening or lengthening, the pressure loss of the filter can always be kept within the set range under any dust collection conditions, and the dust collector can be operated stably and economically. DESCRIPTION OF THE PREFERRED EMBODIMENTS It is an object of the present invention to provide an improved filter dust removal device for a dust collector, and embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic diagram of a pulse jet dust collector embodying the present invention. In the figure, 1 has a dust suction port 2 on the bottom side, an exhaust port 3 on the top side, and has several rows of filters inside. 4 is installed in multiple rows of dust collection tanks, and when the dust suction fan 6 attached to the exhaust port 3 via the suction pipe 5 is operated to suck dust by the motor 7, the dust side 1 of the dust collection tank 1 is drawn from the dust suction port 2.
A mechanism in which dust in the dust-containing air sucked into a is collected and separated by the filter group 4, and only purified air is exhausted from the clean side 1b through the suction pipe 5 and from the dust suction fan 6. It has become. Also, the reference numeral 8 in the figure indicates a pulse jet type dust remover, and this dust remover is connected to the header pipe 10 through a compressor 9 that supplies compressed air to the header pipe 10 and a solenoid valve 11, respectively. It is composed of the same number of broach tubes 11' as the number of rows of the filter group 4, and the tip side of each broach tube 11' supplies compressed air (pulse jet) to the corresponding filter group 4. So that you can squirt properly,
They are respectively inserted into the clean side 1b of the dust collection tank 1. The solenoid valves 11 attached to the header pipes 10 are sequentially opened and closed at predetermined time intervals by control signals sent from a control section to be described later, and the solenoid valves 11 installed in the header pipes 10 are operated to open and close in sequence at predetermined time intervals. Compressed air for dust removal can be ejected to the filter groups 4 sequentially and at intervals. The compressed air injected from each broach tube 11' is reduced to 50% by the ejector effect of the bench lily part 4a provided at the mouth of each filter.
~7 times the amount of secondary air is drawn from the surroundings and rushes into the filter, deforming the bag-shaped filter by the shock and ejecting backwash air towards the outside of the filter, which has a dust removal effect. This allows dust attached to the filter to be removed. The injection time of compressed air is, for example, 0.04/
One cycle of the dust removal operation is completed by setting this injection to all filter groups 4 at predetermined intervals.

The present invention is used in a dust collector equipped with the dust remover 8 as described above, and in the present invention, the injection time of compressed air, that is, the on-time, is only manually operated, and the period from one injection to the next injection is performed. By controlling the interval between dust removal operations, that is, the off time, using the operation unit described later, it is possible to bring the pressure loss of the filter close to the ideal state, and this can be done according to the drawings. To explain, in Fig. 1, 12 measures the differential pressure before and after the filter, that is, the atmospheric pressure P1 on the dust side _1a side and the atmospheric pressure _P2 on the clean side 1b side, and calculates the differential pressure (filter pressure loss). 13 is a control section that controls the off-time of the dust remover 8 based on the differential pressure detection signal detected by the differential pressure detection section 12.

As shown in the block diagram of FIG. 2, the differential pressure detection section 12 includes a lower limit detection circuit 14 equipped with a lower limit detection switch SW1 that detects the lower limit of the differential pressure, and an upper limit detection switch SW2 that also detects the upper limit of the differential pressure. If the most ideal pressure loss of the filter is set to △P (mmAg), the lower limit value of the differential pressure is, for example, △P-10.
Furthermore, the upper limit value is set in advance to be, for example, ΔP+10. Of these detection switches, the lower limit detection switch SW1 turns on only when the detected differential pressure exceeds the lower limit value △P-10, and the upper limit detection switch SW2 turns on only when the differential pressure exceeds the upper limit value △P+10. It's a system.

The control unit 13 includes the two detection switches SW1 and
It is a sequential controller with a circuit that uses SW2 as a sensor and operates the dust collector when SW1 is on and SW2 is off.
When both SW1 and SW2 are on, the dust remover 8 is controlled to shorten the dust removal operation interval (off time), that is, the compressed air injection interval, for example, by 1 second, and when both SW1 and SW2 are off, the off time is reversed. For example, if SW1 and SW2 are repeatedly turned on or off again, the off time of the compressed air is further shortened or extended by adding, for example, one second.
This is to adjust the differential pressure of the filter so that SW1 is always on and SW2 is off. Control part 1
3 is a lower limit detection circuit 1 as shown in the embodiment of FIG.
Lower limit detection signal _S1 generated from 4 and upper limit detection circuit 1
Upper limit detection signal S ₂ emitted from 5, and output signal sent from the count/decode circuit described later.
The differential pressure confirmation circuit 16 receives S ₁₁ as input, the SW2 ON signal S ₃ generated by the upper limit detection circuit 15, and the SW1 ON and SW2 OFF status confirmation signal S ₄ generated by the confirmation circuit 16 are input as start signals, respectively. an on-timer circuit 17 that performs the on-timer circuit 17, an off-timer circuit 18 that is controlled by inputting the on-signal _S3 and the confirmation signal _S4 of the SW2, and further a count signal _S5 sent from the addition/subtraction counting circuit described later; Both SW1 and SW2 generated by the differential pressure confirmation circuit 16 are turned on.
and an addition/subtraction circuit 19 which inputs the status confirmation signal S ₆ when both SW1 and SW2 are off, and adds and subtracts the deviation signal S ₇ which takes a negative value when both switches are on and a positive value when both switches are off. an addition/subtraction count circuit 20 which outputs the count signal _S5 which is inputted from the circuit 19 and controls the off-time to the off-timer circuit 18 based on the deviation signal _S7 ; and an output generated by the count circuit 20. Counting is performed by inputting the abnormality display circuit 21, which displays an abnormality externally when an abnormality is detected based on the signal _S8 , and the output signals _S9 and _S10 of the on-timer circuit 17 and the off-timer circuit 18. Count/decode circuit 2 for counting and decoding
2, and an output circuit 23 which receives the output signal _S11 generated by the count/decode circuit 22 and specifically controls the dust remover 8.

Figure 3 is an explanatory diagram showing the relationship between the pressure loss △P of the filter and the dust removal operation interval (off time) of the dust removal operation unit 8 in a diagram.When the dust collector starts operating, the pressure loss △P of the filter gradually decreases. rise to SW
2 is turned on, the control unit 13 operates and the dust remover 8
A pulse jet is started. After one cycle of pulse jets (total of 5 times) is completed, if SW1 is off as shown by symbol C, the next pulse jet will be stopped until ΔP rises again and SW2 is turned on again. At this time, the next off time is automatically set to T ₀ +1/sec=T ₁ by the control section 13. Similarly, turn SW2 on to perform the next pulse jet for one cycle, and at the end, SW1 turns on the sign.
When it is off as shown by C′, T ₁ +1/
Extend the second and off time to T ₂ and start the next cycle by turning SW2 on. Also, at the end of one cycle, △P is at the position indicated by symbol D, and SW1,
When both SW2 are on, the control section 13
However, if the off-time is shortened to T ₂ -1/sec, and SW1 is on and SW2 is off at the end of one cycle, the off-time is kept as it is and the cycle is repeated, and from now on, the cycle is repeated. The off time at the start is not the initial setting value, but the Tn time is memorized and the pulse jet starts at this time.

At the end of one cycle of pulse jet,
If the SW2 ON state continues for 10 times or more, the abnormality display circuit 21 operates and displays an abnormality with a yellow lamp, etc., and conversely, if the SW1 OFF state continues for 10 times or more, the abnormality display circuit 21 activates and displays the abnormality with a green lamp, etc. etc. to display abnormalities. At this time, if SW2 changes from on to off and SW1 changes from off to on due to a change in conditions, the lamps and the like go out at that point and are reset.

FIG. 4 is a diagram showing the relationship between on-time A and off-time B when the present invention is implemented.
On-time A is preset to, for example, 0.04 seconds, and in the case shown in the figure, one cycle of dust removal operation is completed with five pulse jets (meaning that there are five rows of filter group 4). .
If the control section 13 temporarily sets the off time B to 10 seconds based on the differential pressure of the filter detected by the delivery detection section, the dust remover 8 injects a pulse jet every 10 seconds to filter the five rows of filter groups 4... Remove dust in order. In this case, one cycle of dust removal operation is 10×5=
50/second, and if the control unit 13 resets the off time B to, for example, 9 seconds due to fluctuations in the differential pressure, the time required for one cycle will be 9 x 5 = 45/second, which is the same as the previous cycle. The time required for one cycle can be shortened by about 5 seconds compared to the case of 1, and the filter ΔP at the end of one cycle can be reduced by that amount.

In the embodiment of the present invention described above, a pulse jet type dust remover that injects compressed air is used as the dust remover 8, but instead of this, a backwash type or vibration type dust remover as described above may be used. In the case of a backwash type, the supply interval (off time) of backwash air by switching dampers etc. may be controlled by the control unit 13, and in the case of a vibration type, the supply interval (off time) of backwash air may be controlled by switching the damper, etc. The interval (off time) of the applied vibrations may be similarly controlled by the control unit 13.

Since the dust removal device for a filter according to the present invention has the configuration as described above, the control section controls the interval of dust removal operation performed by the dust removal machine for the filter, that is, the off time, according to the detected amount of differential pressure before and after the filter. By adjusting this length to make it longer or shorter, and by sequentially adding up and shortening the off time until the differential pressure becomes appropriate, the pressure loss of the filter can always be kept within the upper and lower limits. Since the pressure loss of the filter can be maintained at the desired level by automatically adjusting it within the set range, the differential pressure will not rise or fall without limits.
Therefore, problems such as an increase in filter pressure drop causing a decrease in air volume and deterioration of dust collection efficiency, or conversely, a decrease in pressure drop causing dust leakage and a shortened lifespan of the filter and dust suction motor can all be solved. If the off-time adjustment described above is repeated a predetermined number of times, an abnormality will be displayed and the root cause of the increase or decrease in pressure loss will be investigated, and a decisive problem such as filter destruction will occur. This can be prevented in advance, and since the device automatically adjusts everything, it is extremely simple to operate, and has the advantage of being able to operate the dust collector stably and economically without touching it.

[Brief explanation of the drawing]

The drawings show examples, and FIG. 1 is a schematic diagram of a pulse jet dust collector embodying the present invention, FIG. 2 is a block diagram of the control section which is the main part of the present invention, and FIG.
The figure is an explanatory diagram showing the relationship between the pressure loss of the filter and the off-time by a line, and FIG. 4 is an explanatory diagram explaining the relationship between the off-time and on-time in the present invention.
FIG. 5 is an explanatory diagram showing the relationship between off time and on time in a conventional timer type device. 4... Filter group, 8... Dust remover, 12...
Differential pressure detection unit, 13... Control unit, 14... Lower limit detection circuit, 15... Upper limit detection circuit, 21... Abnormality display circuit, SW1... Lower limit detection switch, SW2...
Upper limit detection switch.

Claims (1)

[Claims] 1. In a dust collector, in which the dust remover automatically repeats the dust removal work of brushing off the dust attached to the filter at a predetermined off-time interval, the operating part of the dust remover is measured to measure the pressure before and after the filter. a differential pressure detection unit that detects the differential pressure of the filter; a differential pressure detection unit that issues upper and lower limit detection signals, respectively, when the detected differential pressure exceeds a set upper limit or lower limit; When the upper limit detection signal is received from the pressure detection means, the off time for the next dust removal operation will be shortened by a predetermined period of time, and on the other hand, when the lower limit detection signal is received, the off time for the next dust removal operation will be extended for a predetermined period, and so on. Reduce and extend off time,
A dust collector characterized by comprising a control section that constantly controls the differential pressure of the filter within the setting range of the upper limit and the lower limit by sequentially adding up the detection signals of the upper limit and lower limit as long as they are sent and received. Filter dust removal device.