JP2023055170A - Bug filter - Google Patents

Abstract

To provide a dust collector having a back-washing mechanism capable of greatly saving energy by exhibiting highest filtering performance and finely optimizing compressed air supply pressure for back-washing according to a filter clogging state.SOLUTION: When a filter is a new product and differential pressure is at an initial reference value, differential pressure immediately before pulse-jetting to a filter column provided with a detection sensor 16 for filter inner pressure is compared with a filter inner pressure increase value after the pulse-jetting at a maximum reference value, and first injection pressure at which the filter inner pressure increase value is higher in absolute value than the differential pressure immediately before the pulse-jetting or injection pressure set one-step lower is selected as pulse jet injection pressure at the initial reference value.SELECTED DRAWING: Figure 1

Description

The present invention relates to a dust collector, which has a mechanism for collecting powder in an airflow with a filter media and blowing off the collected powder with a pulse jet that injects compressed air to the inner surface of the filter (backwashing). Regarding the dust device.

In many plants that handle powder, for example, recovery of products and resources such as flour and lime, or dust contained in the atmosphere (hereinafter, powder such as products, resources, and dust is collectively referred to as "dust"). For the purpose of dust collection, a dust collector using a pulse backwash type bag filter is installed. In such a bag filter, as shown in FIG. 7, the inside of the bag filter main body 1 is partitioned into a clean chamber 3 and a dust-containing airflow chamber 4 by a partition plate 2. An opening 2A is provided to allow communication between the clean chamber 3 and the dust-containing airflow chamber 4 via a filter bag (hereinafter referred to as a filter) 5, which is a filter cloth provided in the chamber. A filter 5 is attached to the opening 2A so as to be suspended in the dust-containing airflow chamber 4 via a retainer with a venturi (not shown). The dust-containing airflow chamber 4 is provided with an intake port 6 for the dust-containing airflow. The clean airflow is filtered by passing through from the inside to be discharged from the discharge port 7 . For the sake of convenience, this dust collection process is referred to as "normal operation".

In the bag filter main body 1, a plurality of filter rows each having a plurality of filters 5 (six in FIG. 7) are arranged in a plurality of rows (five rows in FIG. 8). A plurality of rows of compressed air supply pipes 8 are provided along each row of filters in the clean room 3 , and injection nozzles 9 are provided on the compressed air supply pipe 7 at positions corresponding to the filters 5 . A diaphragm valve 11 is provided between a manifold 10 to which compressed air is sent from a compressor via a pressure regulating valve 13 and each compressed air supply pipe 8, and the diaphragm valve 11 is connected to an electromagnetic valve 12 via a tube 12A. When the solenoid valve 12 is opened, the diaphragm valve 11 is opened, and the backwashing compressed air is instantaneously jetted from the injection nozzle 9 of the compressed air supply pipe 8 toward the inside of the filter 5, and the air in the filter 5 becomes a reverse flow from the inside to the outside even during normal operation.

When the bag filter 1 continues normal operation, the amount of dust trapped on the surface of the filter 5 increases with time, and the resistance (pressure loss) of the filter 5 increases. Dust adheres to the outside of the filter 5, the resistance of the filter 5 increases, the dust collecting function deteriorates, and the reference value (predetermined differential pressure) for determining that the dust cannot be sufficiently captured. When the pressure loss value of the dust-laden airflow flowing from the outside to the inside reaches a reference value requiring cleaning of the filter 5 (dust dust removal), a pulse jet is injected into the filter 5, The pressure in the filter 5 reverses from being negative in normal operation (air flow direction from outside to inside) to positive pressure (air flow direction from inside to outside). For the sake of convenience, this is referred to as "backwashing".

In this way, Patent Document 1 discloses a device that performs backwashing while continuing normal operation. In Patent Document 1, after injecting a pulse jet into the filter 5 (first pulse) during normal operation, the inside of the filter 5 (purified air chamber side) and the outside (dust-containing air Before the pressure difference (inside/outside differential pressure) on the introduction chamber side recovers to the inside/outside differential pressure in the normal operation state, the pulse jet is again injected into the filter 5 (second pulse). At that time, the injection time of the compressed air by the second pulse is set to be longer than the injection time of the first pulse. In this method, a pulse jet longer than the first pulse jet is ejected immediately after lightly impacting the filter 5 to create an environment in which dust can be easily removed, thereby reliably removing dust.

By the way, in Patent Document 1, the pressure of the compressed air stored in the manifold 10 is maintained at a low pressure of 2 Kg/cm2 (approximately 0.2 MPa). Therefore, compared with the conventional bag filter, which tends to be set to a relatively high pressure (for example, 0.5 MPa), the energy saving effect is great. Furthermore, since the pulse jet is injected a plurality of times, it is particularly effective when the amount of dust is large.

However, when the dust is highly adherent (adhesive, cohesive, deliquescent, etc.) or when the filter 5 is nearing the end of its life due to accumulated clogging of the filter 5, the pressure may be insufficient. Therefore, the effect of backwashing cannot be exhibited sufficiently. In this sense, Patent Document 1 does not disclose the optimization of the injection pressure of the pulse jet.

Therefore, in Japanese Patent Laid-Open No. 2002-100003, in order to perform accurate brushing off according to the degree of clogging of the filter 5, the pressure inside and outside the filter 5 is detected while the pulse jet is being injected toward the inside of the filter 5, A dust collector is disclosed in which the injection time and pressure of the compressed air can be controlled such that the pressure difference is positive within the filter. When the pulse jet is injected, the compressed air is injected (pulse jet) at a pressure such that the inside of the filter 5 is always in a positive pressure state compared to the pressure in the dust-containing airflow chamber to ensure the backwashing effect, Conversely, when the pressure inside the filter 5 is negative with respect to the outside, it is determined that the dust on the surface of the filter 5 is not removed, and optimization control is performed so that the pressure inside the filter 5 is always positive. is.

Japanese Patent No. 5216692 JP 2003-290618 A JP 2012-247056 A

However, in Patent Document 2, the backwashing effect is not guaranteed unless the inside of the filter 5 is always in a positive pressure state. In this case, the injection conditions of the pulse jet are set to values more than necessary (for example, a higher pressure and a longer injection time), and it is difficult to achieve proper control when the filter is new.

As the filter 5 nears the end of its life and becomes clogged severely, the pressure difference between the inside and outside of the filter 5 increases. Although it becomes pressure, it is actually in a state where it cannot be wiped off, and proper control cannot be performed for the filter nearing the end of its life.

In other words, as a means of confirming the backwashing effect, focusing only on maintaining a positive pressure inside the filter by comparing the pressure difference between the inside and outside of the filter with the outside does not allow the initial filter 5 when it is new or the filter 5 to be replaced when it is clogged. It is not possible to optimally and effectively backwash the filter 5 at the end of its life.

Therefore, in Patent Document 3, a pilot diaphragm valve is provided in the diaphragm valve to increase the response speed of the compressed air flowing into the compressed air supply pipe 8 (conduit), and a sleeve-shaped guide member is attached to the main diaphragm assembly member. A diaphragm valve is disclosed that prevents an increase in pressure loss and increases the amount of compressed air injected from the diaphragm valve into the filter 5 without increasing the pressure of the compressed air.

However, in Patent Document 3, the inflow speed of the compressed air from the diaphragm valve to the compressed air supply pipe 8 (conduit) is increased, and even though the amount of inflow to the compressed air supply pipe 8 (conduit) is increased, the diaphragm Pipe line resistance downstream from the valve, that is, pressure loss in the compressed air supply pipe 8 (pipe) and injection nozzle 9 on the side of the bag filter 1 is not considered.

In view of the above-mentioned problems, the present invention maximizes the filtration performance according to the clogging state of the filter 5 (from new to the end of life) while supplying compressed air for backwashing ( Pulse jet) pressure is finely optimized to prevent excessive pressure supply, extend the life of the filter 5, and minimize pressure loss of compressed air, dust collection equipped with a backwash mechanism that can achieve significant energy saving. An object is to provide an apparatus.

The dust collector according to the present invention has a plurality of rows of filter rows each having a plurality of bag-shaped filters, and the dust-containing airflow sucked into the dust-containing airflow chamber is passed from the outside to the inside of the filter to remove the dust. After filtering, while performing normal operation in which the cleaned airflow is discharged through the clean room, a pulse jet that injects backwashing compressed air from the inside of the filter removes dust adhering to the outside of the filter. A backwashing process is performed, and this backwashing process is performed for each filter row. At least one detection sensor for measuring the pressure in each chamber is provided in each of the dust-containing airflow chamber and the clean chamber, and further, A filter internal pressure detection sensor for measuring the internal pressure of the filter is provided in at least one filter in one cycle of all or some of the multiple filter rows. . Then, from the numerical values detected by these at least three detection sensors, the differential pressure between the dust-containing airflow chamber and the clean chamber, the filter inside-outside pressure difference between the dust-containing airflow chamber and the filter internal pressure, It has a backwashing mechanism equipped with a detection unit that calculates the filter internal pressure rise value, which is the difference in the filter internal pressure before and after the pulse jet, and backwashes when the filter is new (the differential pressure is the initial reference value). At the maximum reference value, the injection pressure of the compressed air for the filter is determined by dividing the differential pressure immediately before pulse jetting into the filter row to which the filter equipped with the filter internal pressure detection sensor belongs, and the filter internal pressure rise value after pulse jetting. By comparison, the first injection pressure at which the filter internal pressure rise value becomes higher in absolute value than the differential pressure immediately before the pulse jet or the injection pressure set one step lower than that is selected as the injection pressure of the initial reference value. .

By selecting the injection pressure of the initial reference value in this way, the energy required for the pulse jet when the differential pressure is within the range of the initial reference value can be further optimized (energy saving).

Next, in the dust collector of the present invention, when determining the injection pressure of the backwashing compressed air during normal operation when the differential pressure of the entire bag filter exceeds the initial reference value and reaches the maximum reference value, the following is performed: judge as When the differential pressure across the bag filter tends to rise above a certain set reference value, the differential pressure inside and outside the filter is detected, and the differential pressure inside and outside the filter before the pulse jet is compared with the differential pressure inside and outside the filter after the pulse jet. , If it can be confirmed that the decrease value of the differential pressure inside and outside the filter after the pulse jet has decreased to the same value as the decrease value of the differential pressure inside and outside the filter one cycle before, the injection pressure is maintained as it is, and the pulse Decrease the jet spacing T.

Even though the dust is thoroughly blown off by the pulse jet, the fact that the overall differential pressure tends to rise means that more dust is sucked into the dust-containing airflow chamber than the amount of dust that is blown off by a single row of pulse jets. Since it can be determined that the amount of dust to be discharged is larger, it is possible to prevent unnecessary increase of the injection pressure.

In addition, the dust collector of the present invention is another judgment when determining the injection pressure of the backwashing compressed air during normal operation when the differential pressure of the entire bag filter exceeds the initial reference value and reaches the maximum reference value. The materials are as follows. When the differential pressure across the bag filter tends to rise above a certain set reference value, the differential pressure inside and outside the filter is detected, and the differential pressure inside and outside the filter before the pulse jet is compared with the differential pressure inside and outside the filter after the pulse jet. , when it is confirmed that the decrease value of the differential pressure inside and outside the filter after the pulse jet is smaller than the decrease value of the differential pressure inside and outside the filter one cycle before, the injection pressure is increased by one step.

If the differential pressure across the bag filter tends to rise and the blow-off effect is dulled, it can be determined that the power of the pulse jet is insufficient. The clogging problem can be properly solved.

In addition, in the dust collector of the present invention, when the differential pressure, which tends to rise above the set reference value, continues in a stable state within the set range of the set reference value, the narrowed pulse jet It is characterized by widening the interval T or lowering the increased injection pressure.

If the differential pressure, which has been on the rise, is sufficiently wiped off by narrowing the interval T of the pulse jet and increasing the number of pulses, or by increasing the injection pressure, raise the setting of the reference value. There is no need, the injection pressure and frequency of the pulse jet can be suppressed to a low level, the burden on the filter can be reduced, and it is also effective for energy saving.

Next, when the differential pressure across the bag filter exceeds the maximum standard value, the differential pressure stops at a value higher than the maximum standard value, and compared to the differential pressure inside and outside the filter before the pulse jet, the pulse When it is confirmed that the decrease value of the differential pressure inside and outside the filter after jetting is significantly smaller than the decrease value of the differential pressure inside and outside the filter one cycle before, the filter is replaced with a new filter.

The sign of filter life can be clearly determined, and preventive maintenance can be achieved by early replacement.

Further, the dust collector of the present invention is characterized in that the injection time of the pulse jet is uniform regardless of any set value from the initial reference value to the maximum reference value.

Only the injection pressure and number of injections (injection intervals) can be considered as the conditions for optimizing the injection conditions (pressure) to maximize the effect of the pulse jet. realizable.

In addition, depending on the clogging state of the filter (from new to the end of its service life), while maximizing filtration performance, the pressure of the compressed air supply for backwashing is finely optimized to prevent excessive pressure supply. Extends filter life and minimizes compressed air pressure loss to achieve significant energy savings.

FIG. 4 is a diagram schematically showing the relationship between the differential pressure across the entire bag filter of the present invention, the measurement positions of the pressure inside the filter, and the control unit that reflects the measurement results in the backwashing conditions. In the new filter of the present invention and the filter in steady operation, the pressure in the manifold, which is the pressure source, is 0.3 MPa, and the pressure difference across the entire bag filter before and after backwashing, and the increase in the pressure inside the filter. It is a graph which shows the result of having measured. 5 is a graph showing differences in filter internal pressure rise values according to differences in pressure in a manifold, which is a pressure source, during normal operation of the bag filter according to the present invention. FIG. 10 is a table and a flow showing countermeasures according to the cause of an increase in differential pressure across the entire bag filter during normal operation of the bag filter according to the present invention; FIG. 5 is a graph schematically showing the relationship between the differential pressure across the entire bag filter, the differential pressure inside and outside the filter, and the injection pressure of the pulse jet, from a new filter to a filter nearing the end of its life according to the present invention. 4 is a graph showing changes in the differential pressure of the bag filter due to the difference in injection time of the pulse jet. FIG. 10 is a front cross-sectional view showing a conventional bag filter; FIG. 3 is a plan view cross-sectional view of a conventional bag filter.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each figure, the same reference numerals are given to the same or corresponding parts.

FIG. 1 is a diagram schematically showing the relationship between the differential pressure of the bag filter of the present invention, the measurement positions of the filter internal pressure, and the control unit that reflects the measurement results in the backwashing conditions. Reference numeral 14 is a sensor for detecting the pressure (Pd) inside the dust-containing airflow chamber, reference numeral 15 is a sensor for detecting the pressure (Pc) inside the clean chamber, and reference numeral 16 is a sensor for detecting the pressure (Pf) inside the filter. be. The position of each sensor is not limited to the illustrated position. Reference numeral 17 denotes a detection unit that detects or calculates the pressure of each detection sensor, the pressure difference, and the like.

Here, the pressure inside the dust-containing airflow (Pd.P means "Pressure", d means "dirty" or "dust") and the pressure inside the clean room (Pc.c means "c." of "clean"), For convenience, the pressure difference (Pd-Pc) of the entire bag filter 1 is referred to as the "differential pressure (ΔP)" of the entire bag filter 1, the dust-containing airflow internal pressure (Pd) and the filter internal pressure (Pf. f is f in "filter"). The pressure difference (Pd−Pf) between the pressure inside and outside the filter (ΔPf) is defined as the “differential pressure inside and outside the filter (ΔPf),” and the pressure inside the filter (Pfb) before injecting backwashing compressed air (pulse jet) into the filter 5. b is “before "b.") and the filter internal pressure immediately after the pulse jet is injected into the filter 5 (Pfa. a is "after" a.). Pfb|. Hereinafter, it is indicated as an absolute value, and in is "in of "inside".)".
In the following, the alphabet used after P will be appropriately attached in accordance with the above description.

The control unit 18 stores a reference value that serves as a criterion for adjusting the pressure of the compressed air in the manifold 10 according to the clogging state of the filter. The reference value is the differential pressure (ΔP) during normal operation, the initial reference value (ΔPstart) (for example, 0.5 kPa) when the filter is new, and the maximum value for stable normal operation after leaving the initial reference value. Reference values up to the reference value (ΔPmax) (for example, 1.5 kPa) are stored (set). When the differential pressure (ΔP) exceeds the maximum reference value (ΔPmax), it can be determined that the filter 5 has reached the end of its service life and it is time to replace the filter 5 with a new one. The bag filter 1 basically adjusts the injection pressure of the pulse jet and the interval of the pulse jet to the best value for each set reference value when the differential pressure is between the reference value of 0.5 kPa and 1.5 kPa. By doing so, normal operation can be continued until the life of the filter 5 expires.

By the way, supply of backwashing compressed air (pulse jet) is performed for each filter row. Therefore, as the number of filter rows increases, the fluctuation of the differential pressure (ΔP) of the entire bag filter 1 due to the removal of only one row becomes very small, and the effect of removal can be accurately known only from the differential pressure (ΔP). It is difficult. On the other hand, when the detection sensor 16 is arranged in the filter 5, the filter pressure (Pf) before and after the pulse jet, the filter pressure difference (ΔPf), and the filter pressure rise (ΔPfin) are higher than the pressure difference (ΔP). There is an advantage that changes can be read clearly. Therefore, by using the filter internal pressure (Pf), it is possible to determine the shake-off effect more accurately and finely adjust the optimum supply conditions for each reference value.

In this embodiment, the bag filter 1 having 12 rows of filters 5 each composed of 8 filters 5 (the total number of filters 5 is 96) is used, and the internal pressure (Pf) of the filter 5 is The detection sensor 16 for detection is provided only in one of the eight filters 5 forming the filter row and only in the first row of the 12 rows. Of course, the number of detection sensors 16 is not limited to this, and one sensor may be attached to each filter row, or one sensor may be attached to every two rows, three rows, four rows, or six rows. . Also, two or more may be provided in one row.

FIG. 2 shows the pre-pulse differential pressure (ΔPb) and the post-pulse differential pressure (ΔPa) when the manifold 10 pressure is set to 0.3 MPa when injecting the pulse jet from the injection nozzle 9 into the filter 5 (pulse), and the pulse It is an actual measurement value of the pressure rise value (ΔPfin) in the filter at the time. The graph on the left end of FIG. 2 shows the state in which the differential pressure (ΔP) of the filter 5 approaches the maximum reference value of 1.5 kPa, and (1) to (5) on the right (circles 1 to 5 in the figure and table). ) is a graph obtained by measuring five times with a new filter 5 in which the differential pressure is the initial reference value of 0.5 kPa. Below is a tabular version of the graph in FIG.
(Table 1)

From FIG. 2 and Table 1, both the initial reference value (ΔPstart) and the maximum reference value (ΔPmax), the filter internal pressure rise value (ΔPfin) at the time of pulse is higher than each reference value. It can be seen that it is functioning normally. Also, at the initial reference value (ΔPstart), the resistance of the filter 5 is low, and the filter internal pressure rise value (ΔPfin) at that time is less than half of that at the maximum reference value (ΔPmax). .

Next, FIG. 3 and the following table show the differential pressure (ΔP ) and the pressure increase value (ΔPfin) in the filter at the time of pulse are summarized.
(Table 2)

The filter internal pressure rise value (ΔPfin) when the compressed air in the manifold 10 is 0.15 MPa is 1.424 kPa, which is lower than the differential pressure (ΔPb) before the pulse. You can see that it flows inward from the On the other hand, the filter internal pressure rise values (ΔPfin) due to pressures of 0.2 MPa or more are all higher than the pre-pulse differential pressure (ΔPb), and the air flow flows from the inside to the outside of the filter 5 for backwashing. You can see what is being done. This table shows that the supply pressure of the manifold 10 during normal operation is preferably 0.2 MPa or higher.

On the other hand, in FIG. 2 and Table 1, the filter internal pressure rise value (ΔPfin) when the supply pressure of the manifold 10 is 0.3 MPa when the filter is new is 0.7932 kPa (average value). In the table, when the differential pressure (ΔP) approached the maximum reference value and the filter was clogged to some extent, the pressure increase in the filter (ΔPfin) was 1.424 kPa when the supply pressure of the manifold 10 was 0.15 MPa. . Comparing these measured values, when the filter is new, there is almost no adhesion of dust and the resistance is small. ΔPb).

When the filter is new, that is, while the differential pressure (ΔP) of the entire bag filter 1 is at the level of the initial reference value (ΔPstart: 0.5 kPa), the supply pressure of the compressed air from the manifold 10 is as shown in FIG. Supply pressure 0.15 MPa set one step below the pressure at which the backwashing effect shown in 2 (0.2 MPa at which the filter internal pressure rise value (ΔPfin) during the pulse is higher than the pre-pulse differential pressure (ΔPb)) It can be seen that a sufficient backwashing effect can be obtained even if is selected.

This is because a detection sensor 16 is provided in the filter 5 and the filter internal pressure (Pf) is actually measured, so that the filter internal pressure increase value (ΔPfin) can be clearly known, so while clearly confirming the shake-off effect, Excessive compressed air pressure setting can be avoided.

Next, FIG. 4 shows that the differential pressure (ΔP) of the bag filter 1 exceeds the initial reference value (ΔPstart: 0.5 kPa) and reaches the maximum reference value (ΔPmax: 1.5 kPa) in normal operation. It is a table|surface and flow which show the outline|summary about optimization of pulse jet injection conditions, such as backwash pressure.

FIG. 5 shows the differential pressure (ΔP) leaving the initial reference value (ΔPstart), passing through the maximum reference value (ΔPmax), and the transition of the differential pressure (ΔP) increase of the entire bag filter 1 until the filter reaches the end of its life. FIG. 10 is a graph schematically showing the relationship between changes in the reduction width of the differential pressure between the inside and outside of the filter (ΔPf) before and after the pulse, changes in the injection pressure rise of the pulse jet, and the like. FIG.

In FIG. 5, a bag filter having 12 rows of 8 filter rows is provided with a filter internal pressure detection sensor 16 for every 4 rows. These four columns are taken as one cycle. The pulse jet is applied to all rows one row at a time, but the internal pressure (Pf) is measured only in the first row (1st row, 5th row, 9th row, etc. for the entire bag filter 1) for each cycle. .

In addition, the "decreased value of the differential pressure inside and outside the filter (ΔPf)" in FIG. there is When the backwash effect appears, the differential pressure inside and outside the filter after the pulse (ΔPfa) is firmly reduced compared to the differential pressure inside and outside the filter before the pulse (ΔPfb) (for example, ΔPf1), but When the backwash effect is not observed, it indicates that the decrease value is small (eg, ΔPf8).

In FIG. 5, the interval T of the pulse jets is shown as a constant interval, but the interval T may be narrowed or widened depending on the cause of the increase in differential pressure shown in Table 2.

Optimization of the injection conditions of the pulse jet will be explained using Tables 3 and 4, FIGS. 4 and 5. FIG. When the differential pressure (ΔP) of the entire bag filter 1 tends to rise slightly from a certain set reference value, the differential pressure (ΔPf) inside and outside the filter is detected, and the differential pressure (ΔPfb) inside and outside the filter before the pulse is detected. The differential pressure inside and outside the filter after the pulse (ΔPfa) is compared with the differential pressure inside and outside the filter after the pulse (ΔPfa). , and if it is confirmed that there is no change compared with the reduced value of the differential pressure inside and outside the filter one cycle before, it can be confirmed that the shake-off in the pulsed train has been effectively performed.

At this time, even if the sweeping off for each row is effectively performed, the differential pressure (ΔP) of the entire bag filter 1 shows an upward trend from a certain set reference value. It can be determined that the amount of dust flowing in is greater than the amount of dust removed by a single pulsed filter row, and the dust collection load of the entire bag filter 1 is increasing. In this case, it is possible to take countermeasures such as narrowing the pulse jet interval T and increasing the number of pulses while maintaining the injection pressure.
(Table 3) Countermeasures according to factors of differential pressure rise

Next, when the differential pressure (ΔP) across the entire bag filter 1 shows a tendency to rise slightly above a set reference value, the differential pressure inside and outside the filter (ΔPf) is similarly detected, and the differential pressure inside and outside the filter before the pulse is detected. (ΔPfb) is compared with the _differential internal pressure outside the filter after the pulse ( _ΔPfa ). If it is smaller than the decrease value in ₁ ), it means that the effectiveness of the pulse is getting worse. For example, it can be determined that it is necessary to increase the injection pressure for brushing off dust due to factors such as increased dust adhesion due to moisture added to the dust or increased clogging of the filter 5 . In that case, it is dealt with by increasing the supply pressure of the compressed air.

If the pulse jet interval T is narrowed and the number of pulses is increased, or the injection pressure is increased, the sweeping effect will be sufficiently exhibited, and the differential pressure ( ΔP) continues in a stable state within the set range of the set reference value, widen the narrowed pulse jet interval T (reduce the number of pulses), or lower the injection pressure. You can also
(Table 4) Filter health check

In this way, while repeating measures such as increasing the number of pulses (narrowing the pulse interval) and increasing (decreasing) the injection pressure, the differential pressure (ΔP) gradually increases until the reference value also passes through the maximum reference value, and finally reaches the terminal reference value (ΔPend: over 1.5 kPa) that can be said to be the life differential pressure. When the differential pressure (ΔP) reaches the final reference value, as shown in FIG. , the decreased value of the differential pressure between the inside and outside of the filter (ΔPfa) after the pulse remains small, and when this symptom is observed, the filter 5 reaches the end of its life and must be replaced with a new filter 5 as soon as possible.

By the way, in the present embodiment, in order to optimize the injection conditions of the pulse jet, attention is paid only to the three conditions of the set reference value from the initial reference value to the maximum reference value, the number of injections, and the injection pressure. It is unified to 100 msec. There are three reasons why we were able to select only one injection time option regardless of the set reference value. One is the adoption of the diaphragm valve 11 having a pilot diaphragm valve. The second is to increase the bore diameters of the tube 12a that connects the diaphragm valve 11 and the solenoid valve 12, the compressed air supply pipe 8, and the injection nozzle 9 to reduce the pipe resistance as much as possible and reduce the pressure loss in the flow of compressed air from the diaphragm valve. Third, the diameter of the filter 5 is reduced. Through these three optimizations, the pulse jet can be quickly and sharply injected into the filter 5 without wasting the pressure in the manifold 10 .

Fig. 6 shows the results of actual measurement of changes in filter differential pressure when pulse jets were injected 28 times at 10-second intervals at a pressure of 0.2 MPa and injection times of 100 msec and 250 msec. is shown. There is no difference in differential pressure change between 100 msec and 250 msec, which proves that a pulse jet with sufficient power can be generated at 100 msec.

REFERENCE SIGNS LIST 1 bag filter body 2 partition plate 3 clean chamber 4 dust-containing airflow chamber 5 filter bag (bug)
6 (dust-containing airflow) inlet 7 (clean airflow) outlet 8 compressed air supply pipe 9 injection nozzle 10 manifold 11 diaphragm valve 12 solenoid valve

Claims (6)

Having a plurality of filter rows each having a plurality of bag-shaped filters,
The dust-containing airflow sucked into the dust-containing airflow chamber is passed from the outside to the inside of the filter to filter the dust, and then the clean airflow is discharged through the clean chamber while performing normal operation. The backwashing process is performed by blowing off dust adhering to the outside of the filter by a pulse jet that injects backwashing compressed air from the inside of the filter row, and the backwashing process is performed for each row of the filter row, and there are a plurality of Repeating all the rows of the filter row or some of the previous rows as one cycle,
At least one detection sensor for measuring the pressure in each of the dust-containing airflow chamber and the clean chamber is provided,
A filter internal pressure detection sensor for measuring the internal pressure of the filter is provided in at least one of the filters in the one cycle,
From the numerical values detected by these at least three detection sensors, the differential pressure, which is the pressure difference between the dust-containing airflow chamber and the clean chamber, and the filter inside-outside pressure difference, which is the pressure difference between the dust-containing airflow chamber and the filter internal pressure. A dust collector equipped with a backwashing mechanism that includes a detector that calculates the filter pressure rise value, which is the difference between the pressure in the filter before and after the pulse jet, and the like,
The injection pressure of the backwashing compressed air when the filter is new and the differential pressure is the initial reference value is
At the maximum reference value, by comparing the differential pressure immediately before pulse jetting to the filter row to which the filter including the filter internal pressure detection sensor belongs and the filter internal pressure rise value after pulse jetting, The first injection pressure at which the filter internal pressure rise value becomes higher in absolute value than the differential pressure immediately before the pulse jet or the injection pressure set one step lower than the first injection pressure is selected as the injection pressure of the initial reference value. dust device. The injection pressure of the backwashing compressed air during normal operation until the differential pressure exceeds the initial reference value and reaches the maximum reference value is
When the differential pressure tends to rise above a certain set reference value, the differential pressure inside and outside the filter is detected, and the differential pressure inside and outside the filter before the pulse jet is compared with the differential pressure inside and outside the filter after the pulse jet. If it can be confirmed that the decrease value of the differential pressure inside and outside the filter has decreased to the same value as the decrease value of the differential pressure inside and outside the filter one cycle before, the injection pressure remains the same, and the pulse jet interval 2. A dust collector according to claim 1, characterized in that the width is narrowed. The injection pressure of the backwashing compressed air during normal operation until the differential pressure exceeds the initial reference value and reaches the maximum reference value is
When the differential pressure tends to rise above a certain set reference value, the differential pressure inside and outside the filter is detected, and the differential pressure inside and outside the filter before the pulse jet is compared with the differential pressure inside and outside the filter after the pulse jet. when it is confirmed that the decrease value of the differential pressure inside and outside the filter is smaller than the decrease value of the differential pressure inside and outside the filter one cycle before, the injection pressure is increased by one step. 2. The dust collector according to 1. When the differential pressure, which has tended to rise above the set reference value, continues in a stable state within the set range of the set reference value, the narrowed pulse jet interval T may be widened, or 4. The dust collector according to claim 2, wherein the injection pressure is lowered. If the differential pressure exceeds the maximum reference value,
The differential pressure stops at a value higher than the maximum reference value, and the decrease value of the differential pressure inside and outside the filter after the pulse is lower than the differential pressure inside and outside the filter before the pulse. 5. A dust collector according to any one of claims 2 to 4, wherein the filter is replaced with a new filter when it is confirmed that the differential pressure between the inside and outside of the filter is significantly small as well as the reduced value. 6. A dust collector according to any one of claims 1 to 5, wherein the injection time of said pulse jet is uniform regardless of any set value from said initial reference value to said maximum reference value.

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