RU2336930C2 - Sleeve filter to effect three-stage air clearing of mechanical impurities - Google Patents

Abstract

FIELD: engines and pumps.

SUBSTANCE: invention is designed to clear aspiration air withdrawn from wood-working tools containing a mix of wood dust, saw dust and shavings or only 100%-wood grinding fire-and-explosion-dangerous dust, and to feed purified air back into production premises. The said filter comprises filtration modules incorporating dust catcher chambers, dust collectors, filtration sleeves, hoppers and air cell filter panel fitted horizontally in the gap between the dust catcher chambers, above the purified air valve holes, to form an upper chamber communicating with the extra fan inlet branch pipe and an lower chamber communicating with the purified air outlet manifold. The said manifold features two vertical walls with rectangular openings accommodating comb screens made up of flat and corrugated bands.

EFFECT: increased power savings, expanded performances.

13 dwg

Description

The invention is intended for the purification of gas and / or air in industrial premises, the equipment of which pollutes the air, in particular for the purification of aspiration air taken from woodworking machines, containing: a mixture of wood dust, sawdust and wood shavings or only 100% wood grinding dust with solid abrasive particles, which is fire and explosive, and the return of purified air to the production room.

The essence of the proposed decision.

To obtain a higher technical result compared with the known solutions, namely, to reduce energy costs during air purification and to expand the filter’s functionality, the air cell filter panel is installed horizontally in the gap between the dust collecting chambers under the valve openings for purified air along the entire length of a number of modules with the formation the upper chamber of purified air, which is connected to the suction pipe of the additional centrifugal fan and the lower measures of additionally purified air, made with one open end, to which a purified air outlet manifold is attached, protruding beyond the range of modules and having two vertical side walls with rectangular windows in which honeycombs are made of flat and corrugated heat-resistant material tapes having the total living area of the corrugations, which prevents the passage of fire through them with the installed capacity of the main centrifugal fan, in addition to receiving manifold of purified air at the outlet of the honeycomb grids connected to the receiving manifolds of variable cross section, the outlet openings of which are connected to the nozzles of the collecting tee, connected at the outlet to the suction nozzle of the main centrifugal fan.

The invention, the solution relates to the field of purification of air or gas, as well as mixtures thereof from mechanical impurities, in particular to the purification of suction air taken from woodworking machines containing a mixture of wood dust, sawdust and shavings, or 100% wood grinding dust, which is fire and explosion hazard, and return of purified air to the production room. The claimed solution can be used in milling, textile, chemical and other industries in which the production air contains 100% fire and explosive dust such as wood grinding.

From the sources of scientific, technical and patent information, a large number of modifications of bag filters are known. Among them, as analogues and prototype, those were selected in which the dust-collecting chambers of the filter bags are installed in rows with the formation of a gap between them, in which the collectors of polluted and purified air are installed, and the filter fabric is regenerated by reverse sectional purging of the bags with purified air, which makes it possible to further their improvement in the direction indicated in the claims of the claimed solution.

The known filter С C1 B01D 46/02, containing at least one row of filter modules, each of which has two dust collecting chambers with sections between vertically arranged filter bags, installed with a gap between their side walls, manifolds of variable cross-section for the input of contaminated and the output of purified air placed in the gap between the dust collecting chambers, a purge air collector, a main centrifugal valve a heater and a recirculation air duct with a tee connected to the discharge pipe of the main centrifugal fan, an additional centrifugal fan, the suction pipe of which is connected to a tee installed on the discharge recirculation air duct of the main centrifugal fan, and the discharge pipe with the inlet of the purge air manifold, louvres installed under each dust collecting chamber, valve boxes mounted on dust tube sheets collecting chambers, with poppet type actuating valves located in them, interacting in turn with two coaxial openings located one on the purge and purified air collectors along their horizontal axis one above the other in each valve box, and two mirror-mounted valve boxes of one module have a common a partition separating pairs of their coaxial holes, a hopper with a discharge device for mechanical impurities. In addition, the filter contains at least one single-row panel of air cell filters located in the inlet of the confuser installed between the collectors of contaminated and purified air along the entire length of the row of modules and an additional collector of variable cross section, the inlet of which is connected to the outlet of the cleaned collector air, and the outlet of the confuser - with the suction pipe of the main centrifugal fan.

The filter is as follows.

Polluted air containing chips, sawdust and wood dust from the collector to enter the polluted air of each row of modules enters the hoppers. The flow of contaminated air, enveloping the guiding shields, passes through the louvres, leaving shavings, sawdust in the hopper part, and then enters the filter bags and the panel of air cell filters of the type FYAK, in which the air is cleaned of wood dust, the cleaned air is supplied by the main centrifugal fan to recirculation duct. The filtering process in the sleeves is carried out during the estimated time, controlled by a time relay, after the operation of which an additional centrifugal fan is turned on and the process of sequential regeneration of the hose sections begins.

To regenerate the filtering fabric of the bags, the valve opening of the cleaned air of the regenerated bag section is closed and the valve hole of the purge air is opened. An additional centrifugal fan draws purified air from the tee mounted on the discharge recirculation air duct of the main centrifugal fan, and feeds it through the purge manifold and valve hole into the valve box of the regenerated hose section. In this case, the filter bags are blown in the opposite direction. Dust from the sleeves is discharged into the hopper part of the filter, and the polluted purge air enters the collector of polluted air and, passing through the louvred grilles, is distributed among the bag sections operating in the filtration mode, after which it is additionally cleaned in the cell filter panel of the type ФЯК and enters the main centrifugal fan.

The main centrifugal fan in filtration and regeneration modes has different performance. In regeneration mode, greater performance than in filtration mode, by the amount of performance of the additional centrifugal fan. The performance control of the main centrifugal fan during the transition from the filtration mode to the regeneration mode and vice versa is carried out by means of a controlled throttle valve installed inside the recirculation duct.

The differences of the known filter are that on all the rods of the poppet type drive valves the upper and lower poppet valves are pivotally mounted, between which compression springs are placed. Slides in the form of a rectangular body are rigidly fixed on the rods, having guide and cantilever mounted rollers interacting with cams made with an internal concave working profile with a gap and rigidly mounted on the drive camshaft with a uniform angular displacement around the circumference relative to each other by an angle φ = ( 360 ° -α) / n, (where α = 25 ... 30 ° is the angle of combination of the regeneration cycles of adjacent hose sections, n is the number of hose sections). The hinges of the poppet valves are made in the form of ball bearings, in which the balls have through holes with rods movably mounted in them with the possibility of alternately lifting the upper and lower poppet valves.

These differences, providing the replacement of the pneumatic valve actuator with an electromechanical actuator with cam camshaft, reduce operating costs and the cost of manufacturing the filter.

The above bag filter has the following disadvantages.

1. Has a hose section regeneration system dependent on the main centrifugal fan by reverse sectional purging of the sleeves with purified air, in which purge air is passed through the main centrifugal fan, which causes increased energy costs for cleaning the air in the filter.

2. Has limited functionality, as When cleaning the aspiration air from mechanical impurities containing only 100% fire and explosive dust, such as wood grinding dust, the filter, due to the lack of a permanent fire retention system at the outlet of the dust-air mixture in the filter, does not prevent the spread of fire blast wave through a recirculation duct into a fire and explosion hazardous production room, for example, for fine grinding of furniture parts, panels or plywood.

The closest in technical essence and the achieved result is "Filter bag for air purification from mechanical impurities", patent No. 2173207 C1 with priority dated January 13, 2001, IPC B01D 46/02, which contains at least one row of filter modules , each of which has two dust collecting chambers installed with an interval between their side walls, equipped with tube sheets with through pipes and sections of vertically arranged filter bags fixed with open ends to pipe pipes air inlet, hopper with openings for entering contaminated air in which rotary shutters are installed, and an opening for discharging mechanical impurities, collectors of variable cross-section for introducing contaminated and discharging purified air, located in the gap between the dust collecting chambers, a purge air manifold equipped with an inlet shut-off valve with an actuator, valve boxes with a poppet type actuating valve located in each of them, interacting in turn with two coaxial holes Arranged one on collectors and purge of purified air on their horizontal axes one above the other with two mirror box disposed one valve module have a common partition wall separating the pair of aligned openings, and a centrifugal fan.

The known filter differs in that the tube sheets are installed in the upper part of the dust collecting chambers, and the filter bags are fixed on them with their upper open ends, the holes for introducing contaminated air into the bunkers are equipped with guiding shields, and the holes for removing mechanical impurities from the bins are equipped with gate unloaders, located in adjacent rows of modules in a checkerboard pattern, in the upper part of the hopper, under each dust collecting chamber, a louvre grille is inclined, valve boxes are installed us to tubesheets, and valve boxes - sealed service chamber, a centrifugal fan is installed at the front end of each row of modules and is provided with a recirculation duct from a tee connected to a discharge pipe of the centrifugal fan.

In addition, the filter is equipped with at least a single-row panel of air cell filters located in the inlet of the confuser, installed between the collectors of contaminated and purified air along the entire length of the row of modules, and an additional manifold of variable cross section, the inlet of which is connected to the outlet of the cleaned collector air, and the outlet of the confuser with the suction nozzle of the centrifugal fan, while the purge air manifold is equipped with an additional centrifugal a fan, the suction pipe of which is connected to a tee mounted on the discharge recirculation duct of the main centrifugal fan, and the discharge pipe of the additional fan is connected to the inlet of the purge air manifold. The hopper is made of three parts, the upper of which has a square section, and the lower one is made in the form of a cylinder with a flat bottom, on the inner surface of which a cylindrical shell is installed along its central axis, forming an annular groove with the inner surface of the cylinder and its bottom, in the bottom of the gutter an opening for discharging mechanical impurities into the lock unloader, in addition, a drive is installed under the cylinder bottom, and a through hole for the drive shaft is made in the bottom along its central axis, on which The frame of the conical-cylindrical unloading device is fixedly fixed, the lower cylindrical part of which is placed with a technological gap outside the shell in the annular groove, while at least two blades are radially fixed to the outer surface of the cylindrical part of the unloading device, the length of each of which is less than or equal to the difference between the inner radius of the cylinder and the outer radius of the cylindrical part of the unloading device.

Despite the large number of coinciding features of the prototype and the proposed solution, the absence of the distinctive features of the latter in the prototype does not provide a technical result, which consists in reducing energy costs when cleaning air and expanding the filter's functionality for the following reasons.

1. The filter has a hose section regeneration system dependent on the main centrifugal fan by reverse sectional purge of the bags with purified air, in which purge air is passed through the main centrifugal fan, causing increased energy costs for air purification.

2. The filter has limited functionality, because when cleaning aspiration air from mechanical impurities, which include only 100% fire and explosive dust, for example, wood sanding, the filter, due to the absence of a permanent fire retention system at the outlet of the dust-air mixture in the filter, does not prevent the spread of blast wave through a recirculation duct into a fire and explosion hazardous production room, for example, for fine grinding of furniture parts, panels or plywood.

Depending on the main centrifugal fan, the system for regeneration of hose sections by reverse sectional purging of the hoses with purified air causes increased energy consumption for air purification for the following reasons. Passing purge air through the main centrifugal fan leads to an increase in the capacity L _{in the} main centrifugal fan in the calculated regeneration mode (one hose section is in the regeneration mode, the other hose sections are in the filtering mode).

The increased amount of air in the regeneration mode passes through the hose sections involved in the filtration, valve openings, the cleaned air manifold, exhaust, as well as through the panel of cellular air filters of the FYAK type, the confuser and part of the recirculation air duct to the tee, which is the place for intake of purified air by an additional centrifugal fan . At the same time, the air flow rates in the above elements increase and the pressure losses in them increase, which lead to an increase in the pressure developed by the main centrifugal fan N _c . Since the estimated engine power P _er of the fan is directly proportional to the product of the productivity L _in and the pressure N _{in the} fan, then with increased values of the parameters of the fan L _in and H _in , the calculated engine power R _er fan and increases energy consumption for air purification during operation of the filter.

The absence of a permanent fire retention system at the outlet of the filter will lead to the fact that during the cleaning of aspiration air from mechanical impurities, which include only 100% fire and explosive dust, and the explosion of the dusty air mixture in the filter, the fire that has arisen due to a huge excess explosion pressure, of the order of (2.5-10) 10 ³ kPa, will instantly propagate by a blast wave through a recirculation duct into an explosive production room in which a secondary explosion will occur with possible human the victims.

The known design of shut-off valves installed at the outlet of the filters does not provide 100% reliability of the functions of fire barriers, because the shut-off valve is actuated by electromagnets through intermediate relays from the sensor, each of which may fail, resulting in a failure to operate the shut-off valve.

In addition, shut-off valves do not have sufficient response speed to cut off a fire and explosion hazardous production room from an instantly propagating blast wave of fire in the event of the formation of an dust-air mixture explosion from a static electricity discharge directly in the filter itself.

The task, the claimed solution is aimed at, consisted in further improving the known design of the bag filter with three-stage air purification from mechanical impurities, which include chips, sawdust and wood dust, and obtaining a technical result - reducing energy costs for air purification and expanding functional filter features due to:

1) the creation of an energy-saving system for regenerating the sectional reverse purging of hoses with purified air, independent of the main centrifugal fan, which eliminates the passage of purge air through the main centrifugal fan, which will reduce the capacity L _in and the pressure N _{in the} main centrifugal fan in the calculated mode of regeneration of the hose sections and as a result, to reduce the installed power of the fan motor and energy costs for air purification in the filter D;

2) the creation of a permanent fire retention system at the outlet of the filter, which prevents the spread of fire through the recirculation duct when the dust-air mixture explodes in the filter, which will allow the filter to purify air from mechanical impurities, which include only 100% fire explosive dust, such as wood grinding, and thereby ensure the expansion of the filter.

The achievement of the above technical results is ensured by the fact that the bag filter for three-stage air purification from mechanical impurities, containing at least one row of filter modules, each of which has two dust collecting chambers installed with an interval between their side walls, equipped with tube sheets in the upper part with through pipes and sections of vertically arranged filter bags secured by upper open ends to the pipes of the tube sheets, the collector is variable cross-section for introducing polluted air, located in the interval between the dust-collecting chambers, a collector for cleaned air, a purge air collector equipped with an inlet valve, a main centrifugal fan installed at the front end of each row of modules, and a recirculation air duct, valve boxes installed on tube sheets with poppet type actuating valves located in them, interacting in turn with two coaxial openings for purging and cleaning in air located on the horizontal axis of the purge air collector one above the other in each valve box, and two mirror-mounted valve boxes of one module have a common partition separating pairs of their coaxial openings, a sealed service chamber mounted on the valve boxes, a hopper made of three parts , the upper of which is square, and the lower is cylindrical, in the upper part of the hopper there are holes for the input of contaminated air, equipped with guide shields rotary dampers installed on the central partition dividing the hopper vertically, a louvre grille is obliquely installed under each dust collecting chamber, and the lower cylindrical part of the hopper is made in the form of an annular groove with an opening for unloading mechanical impurities into the gate unloader with the location of the gate unloaders in adjacent rows of modules in staggered, above the trench along the axis of the cylindrical part, a drive conical-cylindrical-shaped unloading device with a blade is installed and mounted radially on the outer surface of the cylindrical part and lowered into the trough, in addition, the filter contains at least one single-row panel of air cell filters, and the purge air manifold is equipped with an additional centrifugal fan, the discharge pipe of which is connected to the inlet of the purge manifold, characterized in that the panel of air cell filters is installed horizontally in the gap between the dust collecting chambers under the valve openings for cleaning about air with the formation of an upper chamber of purified air, which is connected to the suction pipe of an additional centrifugal fan, and a lower chamber of additionally purified air, made with one open end, to which a manifold of the outlet of purified air is connected, which extends beyond a number of modules and has two vertical side walls with rectangular windows in which honeycomb lattices are built, made of flat and corrugated tapes of heat-resistant material, having a total living area of corrugation, which prevents the passage of fire through them with the installed capacity of the main centrifugal fan, in addition, to the manifold of the cleaned air at the outlet of the panels of the fire barriers are connected to the receiving manifolds of variable cross section, the outlet openings of which are connected to the nozzles of the collecting tee, connected at the outlet to the suction branch pipe of the main centrifugal fan.

The proof of the materiality of the differences and the relationship of the features with the achieved technical results are disclosed sequentially in the following order.

1. Reducing energy costs when cleaning the air in the filter.

2. Extension of filter functionality.

The reduction of energy costs when cleaning the air in the filter is carried out by installing a panel of air cell filters horizontally in the gap between the dust collectors under the valve openings for cleaned air with the formation of an upper chamber of purified air, which is connected to the suction pipe of an additional centrifugal fan, and a lower chamber of additional purified air made with one open end to which a manifold of cleaned air outlet is connected ayuschy beyond the row of modules and having two vertical side walls with rectangular windows.

Connecting the upper chamber of purified air to the suction pipe of an additional centrifugal fan allows purging air to be drawn through the bag sections from the hopper part of the filter and participating in the filtration and to allow the purge air to move along the closed ring: “hopper part of the filter - louvered grilles - bag sections participating in the filtration - valve openings for purified air - upper chamber of purified air - suction duct - additional centrifugal valve Yator - purge manifold - valve opening for purge air - valve box - blown tubular section - bunker of the filter. "

At the same time, purge air is not passed through the main centrifugal fan, which ensures a decrease in the performance L _{in the} main centrifugal fan, a decrease in the air flow rates in the filter elements and pressure losses in them, which leads to a decrease in the pressure developed by the main centrifugal fan N _c . Decreasing the values of the parameters of the main centrifugal fan L _in and H _in allows you to switch to the characteristic curve of the fan with a lower rotational speed of the fan impeller, which will reduce the installed motor power P _{e of the} main centrifugal fan and reduce energy costs when cleaning the air during operation of the filter.

Let us take as an example an aspiration pneumatic conveying system with air recirculation (ASPTS RV) with an eight-section bag filter installed in it with a three-stage purification of air from mechanical impurities and compare the energy costs in the ASPTS RV network when two regeneration systems with reverse sectional purging of the bags by purged air are used in the filter (dependent on the main centrifugal fan of the regeneration system with a purge air intake from the discharge pipe of the main centrifugal the fan used in the prototype filter, and independent of the main centrifugal fan of the regeneration system with a purge air intake from the upper purified air chamber, made by the claimed solution).

As the source data, we take:

1) the nominal capacity of the main centrifugal fan (at the end of the filtration mode) L _nom = 12500 m ³ / h for two regeneration systems;

2) the performance of the additional centrifugal fan L _pr = 1800 m ³ / h for two regeneration systems;

3) the performance of the main centrifugal fan in the calculated regeneration mode (end of regeneration):

(4,166 м³/с) - фиг.12, кривая 1;- for a filter with a dependent regeneration system

(4.166 m ³ / s) - Fig. 12, curve 1;

- for a filter with an independent regeneration system

(3,66 м³/с) - фиг.12, кривая 2.

(3.66 m ³ / s) - Fig. 12, curve 2.

At the same time, the total pressure loss in the calculated mode in the network of automatic control system of automatic transmission system РВ _{ΔР ∑АС} and the pressure of the main centrifugal fan N _in will be:

и

- with a filter having a dependent regeneration system,

and

и

- with a filter having an independent regeneration system,

and

и

необходимо в рециркуляционном воздуховоде установить дроссельную заслонку с гидравлическим сопротивлением ΔР_д.з:To output the main centrifugal fan to the calculated mode with parameters

and

it is necessary to install a throttle valve with hydraulic resistance _{ΔР d.z} in the recirculation duct:

- for option B

- for option P

The estimated engine power of the main centrifugal fan in the calculated mode will be:

- for ASFTS RV with a filter having a dependent regeneration system

The installed engine power of the main centrifugal fan will be P _e = 30 kW. Fan impeller frequency n = 2040 rpm:

- for ASFTS RV with a filter having an independent regeneration system

The installed engine power of the main centrifugal fan will be P _e = 22 kW. The frequency of the impeller of the fan n = 1810 rpm

Thus, the use of an ASFTS RV filter made with an independent regeneration system for tubular sections, i.e. according to the claimed solution, it provides as compared with a filter prototype installed capacity decrease main centrifugal fan motor on? P _e = (30-22) / 30 = 26.6%. In accordance with this, when operating a filter made according to the claimed solution, the reduction in energy costs for air purification in comparison with the prototype filter will be 26.6%.

The expansion of the filter’s functionality is ensured by performing in the filter of the lower chamber additionally purified air with one open end, to which a purified air outlet manifold is attached, which extends beyond the range of modules and has two vertical side walls with rectangular windows in which cellular gratings are made of flat and corrugated tapes of heat-resistant material having a total living cross-sectional area of corrugations, which prevents the passage of fire through them when installed the main centrifugal fan, in addition, receiving collectors of variable cross section, the outlet openings of which are connected to the nozzles of the collecting tee connected at the outlet to the suction nozzle of the main centrifugal fan, are connected to the purified air outlet manifold at the outlet of the honeycomb grilles.

The specified technical solution provides for the purification of air in the filter from mechanical impurities, which include only 100% fire and explosive dust, such as wood grinding, reliable protection of fire and explosive industrial premises from the spread of fire by an explosive wave through a recirculation duct in an explosion dust-air mixture in the filter and, as a result, allows you to expand the functionality of the filter. This is because the claimed solution in the form of creating a fire retention system at the filter outlet does not need a fire detection sensor, actuators and intermediate relays that can cause a failure, as is the case with shut-off valves, and is an independent and constantly operating system .

Fire retention at the outlet of the filter is ensured by the presence in the filter of a large area of honeycomb grids, which ensures a low velocity of purified air through the cell grilles of the order of V = 0.85-1.1 m / s.

A large area of the honeycomb gratings in the filter is ensured by performing a collector for removing purified air protruding beyond a number of modules. This makes it possible to use two vertical side walls of the collector equipped with rectangular windows for embedding honeycomb grids. For example, a filter having a nominal capacity L _nom = 12500 m ³ / h and a height of the lower chamber of additionally purified air N = 2.8 m allows you to install two honeycomb lattices of four 0.7 × 0.7 cassettes in the purified air outlet manifold m on each side of the collector with a total area of honeycomb lattices F _∑ = 3.92 m ² . The indicated area of the honeycomb lattices provides, in the filtration mode, when the filter performance changes within L _f = 13200-12500 m ³ / h, the purified air passes through the honeycomb lattices within V = (0.93-0.87) m / s.

The design of the inventive bag filter is illustrated by the drawings in figures 1-13.

Figure 1 shows a bag filter in plan, composed of three parallel rows of modules, in conjunction with a pneumatic transport closed installation for centralized collection of mechanical impurities; figure 2 is a section aa (figure 1); figure 3 is a section bB (figure 1) of the sleeve sections, the right of which in the purge mode; figure 4 is a transverse section bb of the filter sleeve in purge mode (figure 3); in Fig.5 is a section GG (in Fig.3) of a single-row panel of air cell filters of the type FAK (FAC - filter air cell pocket II class); in Fig.6 is a section DD (in Fig.1) of the hose sections, the left of which is in the filtration mode, the sealed service chamber 38 is not shown in the filtration mode (in Fig.6); Fig.7 is a transverse section EE of the filter sleeve in the filtering mode (Fig.6); in Fig.8 is a longitudinal section MF filter sleeve with a hinged frame (Fig.6); in Fig.9 is a section 3-3 along the central axis of a row of modules with a single-row panel of air cell filters of the FF type (Fig. 1); figure 10 is a view A (figure 9); figure 11 is a diagram of the suppression of explosion in the pipeline; on Fig - cell honeycomb lattice; on Fig - graph of the performance and pressure of the main centrifugal fan type BP 132-30-8.2.01 in the process of filter operation with different systems of regeneration of bag sections: 1 - dependent on the main fan regeneration system, 2 - independent regeneration system ; sections: GV - filtering mode; DE, MG - regeneration mode of hose sections.

The filter 1 (figure 1) is composed of three rows of 2 modules 3 with adjacent walls 4. Each row 2 of the filter modules 3 (figure 3) is equipped with a collector of variable cross-section 5 for the input of contaminated air, at least a single-row panel 6 of air cell filters type of FAC, with a purified air outlet manifold 7, a purge air manifold 8, a main centrifugal fan 9, a recirculation duct 10 returning the cleaned air to the production room, and an additional centrifugal fan 11 for servicing the collector purge air factor 8.

Each of the filter modules 3 (FIGS. 3, 6) contains two dust collecting chambers 12, 13, between which a collector 5 for introducing polluted air is placed, a pair of poppet type valves 14 (FIG. 3), mounted on the rods 15 of the actuators 16, and also two pairs of coaxial valve openings for purge 17 and purified air 18, made under the valves 14 and located one above the other along the axis of the purge air collector 8. Each dust chamber 12, 13 has a tube sheet 19 with through pipes 20 installed in the upper parts of the chamber, section 21 (Fig. 6) of vertically arranged sleeves 22 (Fig. 8), fixed with open ends on the nozzles 20 of the tube sheet 19. In the filtering sleeves, frames 23 are installed in the form of a cross with a hinge 24. The frame 23 is mounted on the central shaft 25 , in the upper part of which there is a horizontal spoke 26. A technological grid 27 is installed in each dust collecting chamber 12, 13. A hopper 28 is installed along the dust collecting chambers with an opening for the input of polluted air 29 and an unloading hole 30 for mechanical impurities .

The purge air manifold 8 at the inlet is equipped with a shut-off valve 31 with an actuator 32.

In addition, the valve 14 of each dust collecting chamber is enclosed in a valve box 33, two mirrored boxes have a common wall 34 separating a pair of coaxial holes 17, 18; the hopper 28 is divided by a central partition 35, on which a rotary shutter 36 is installed in each module 3. Valve boxes 33 with their open part are placed on the tube sheets 19 and equipped with inspection hatches 37, and a valve-tight service chamber 38 is installed on the valve boxes (Fig. 3).

The height hopper 28 is made of those parts, the upper of which is of square section, the middle is the transition from square to circle, and the lower is in the form of a cylinder 39 with a flat bottom 40 and a vertical shell 41 coaxially mounted on it, forming an annular groove 42, in the bottom which has a hole 43 with a flange pipe for attaching a lock unloader 44, along the central axis of the cylindrical part of the hopper, a hole 45 is made in its bottom, into which a vertical shaft 46 of the drive 47 installed under the bottom is inserted, and the drive shaft 46 is rigidly closed the frame 48 with a discharge device 49 for conical-cylindrical mechanical impurities is insulated, while the cylindrical part 50 of the discharge device is placed in the annular groove 42 with a technological gap between the vertical shell 41 and the bottom 40, and are mounted radially on the outer surface of the cylindrical part of the discharge device at least two blades 51. In addition, between the bushing of the frame 48 and the bottom of the hopper 40, a felt seal 52 is installed, and each airlock unloader 44 (conditionally rotated by 90 °) in the cylindrical part of the hopper 28 is equipped with an inspection hatch 53.

The conical part 54 of the discharge device of mechanical impurities has a cone angle that allows free sliding of mechanical impurities down the housing surface in the annular groove 42, and has a technological gap between the central partition 35 and the partition walls 55.

Gateway unloaders 44 in adjacent rows of modules are staggered. In addition, openings 29 for introducing contaminated air into the hopper 28 are provided with guide shields 56 with rounded ends 57, and louvred grills 59 are inclined between the side walls 58 and the guide shields 56 at the top of the bins 28.

Each valve box 33 is equipped with a differential pressure sensor 60 associated with the actuator 16 of the valve 14 and with the actuator 32 of the shut-off valve 31 of the purge air manifold 8.

Panel 6 air cell filters of the type FAC installed horizontally in the gap between the dust collecting chambers 12, 13 under the valve openings for cleaned air 18 along the entire length of a number of modules 3 with the formation of the upper chamber 61 of purified air and the lower chamber 62 of additionally purified air. The upper chamber 61 of purified air through the duct 63 is connected to the suction pipe of an additional centrifugal fan 11, the discharge pipe of which is connected to the inlet of the purge air manifold 8.

The lower chamber 62 of the additionally purified air has two ends, one of which is equipped with an inspection door 64, and the other is made with an open end, to which a manifold 7 of cleaned air outlet is connected, protruding beyond a number of modules 3 and having two vertical side walls 65 with rectangular windows 66, in which honeycomb lattices 67 are built, made of flat 68 and corrugated 69 strips of heat-resistant material having a total living section area, which prevents the passage of fire through them when installed the main productivity of the main centrifugal fan 9. To the collector 7 of the cleaned air outlet at the exit of the honeycomb grilles 67 are connected receiving collectors 70 of variable cross section, the outlet openings of which are connected to the nozzles 71 of the collecting tee 72, connected at the outlet to the suction pipe 73 of the main centrifugal fan 9. Pressure the nozzle 74 of the main centrifugal fan 9 is connected to a recirculation duct 10, in which a throttle valve 75 for outputting the fan is installed 9 to the design mode and the controlled throttle valve 76 to maintain a constant fan 9 when switching the filter bag sections from the filtering mode to the regeneration mode, and vice versa.

The purge air manifold 8 is also provided with a throttle valve 77 for outputting an additional centrifugal fan 11 to the design mode.

Each row 2 of modules 3 of the filter 1 is equipped with a differential pressure sensor 78 (Fig. 9), designed to measure the resistance of the panel 6 of cellular filters of the type ФЯК connected to the upper chamber 61 of purified air and the lower chamber 62 of additionally purified air.

Gateway unloaders 44 with their outlet openings are connected through tees 79 (Fig. 2) with pipelines 80 of a closed pneumatic conveying installation 81 (Fig. 1) for centralized collection of mechanical impurities, having a fan 82, a cyclone 83 and a hopper 84.

Figure 1 also shows local suction pumps 85 with collectors 86 and prefabricated piping 87 of aspiration pneumatic conveying installations through which contaminated air is taken into filter 1.

In each collection pipe 87, an optical flame detector 88 with a signal amplifier 89 is installed at the beginning of the pipeline, and an explosion suppressor 90 in the pipelines at the end of the pipeline, which, according to the book by A.Ya. Korolchenko (Fire and Explosion Hazard of Industrial Dust, Moscow. Chemistry. 1986) consists of a cylinder with a fire extinguishing agent 91 such as ammonium phosphate, a controlled valve 92 and a nozzle 93.

In front of the filter in the pipeline, a shut-off valve 94 is installed, connected with a signal amplifier 89 and designed to cut off the fire from the filter. Under the explosion suppressor 90 in the collection pipe 87 there is an inspection hatch 95 to eliminate the effects of the explosion.

In addition, to reduce the effects of an explosion at the ends of each row of modules 3, explosive membranes 96 (six pieces) are installed in the upper part of the dust collecting chambers 12, 13 and in the lower chamber of the additionally purified air, and for automatic fire extinguishing, the upper part of the hopper 28, the upper chamber 61 of purified air and the lower chamber 62 of additionally purified air are equipped with fittings 97 having one controlled shut-off valve 98 for supplying an inert gas of the gel-hydrocarbon mixture type to the explosion zone, connected through an amplifier 99 sec an optical flame detector 100 installed in the hopper 28.

To prevent the spread of flame into the collection pipe 87 from the filter during the explosion of the dust-air mixture, a fire retardant valve 101 of the AZE type is installed in front of the filter in the collection pipe. To ensure air balance in the workshop, the supply chambers 102 and exhaust 103 of the general exchange ventilation are installed.

A bag filter, consisting of three rows of filter modules, can operate in three modes:

1 - all dust collecting chambers 12, 13 of any row of modules 3 operate in the filtering mode; 2 - one of the dust collection chambers of any row of modules is in the regeneration mode (reverse purging of the sleeve section with purified air), and the rest of the chambers are in the filtration mode; 3 - one of the dust collection chambers is in maintenance or repair mode (replacing a faulty sleeve), and the rest in filtration mode.

In addition, the filter has two emergency modes from the explosion of a dusty air mixture:

4 - explosion mode in the collection pipe 87, formed from sparks that occur when the grinding skin ruptures; 5 - explosion mode in the filter generated from the discharge of static electricity directly in the filter or from a spark surge into the filter hopper. The first and second filter operation modes are independent of the position of the shutoff valve 31 of the purge air manifold 8 (Fig. 9). Therefore, to simplify the algorithm of the filter during the transition from the first mode to the second, reduce the flow of compressed air and increase the life of the actuators 32 in these modes, the shutoff valve 31 of the purge manifold 8 must be kept in the raised position.

In the third repair mode, the shutoff valve 31 of the purge manifold 8 should be lowered to the lower position, in which the purge manifold 8 is disconnected from the additional centrifugal fan 11.

Since one of the technical results of the proposed solution is to expand the functionality of the filter, i.e. the ability to clean the air of 100% fire and explosive dust, such as wood grinding, then the filter will be described to clean air from mechanical impurities consisting only of wood grinding dust.

The filter in the filtering mode (figure 3) works as follows. Polluted air containing wood grinding dust and to be cleaned, enters the collector 5 of variable cross-section of all rows 2 of the filter modules 3 of the aspiration pneumatic conveying installations. Polluted air from the collector 5 of each row of modules enters through openings for introducing polluted air 29 into the bins 28, which are installed under the dust collecting chambers 12, 13. The flow of contaminated gas, passing around the guiding shields 58, passes through the louvres 59 and enters the dust collecting chambers 12, 13, in which sections 21 of vertically arranged sleeves 22 with an external working surface are placed. In this case, large dust particles larger than 70 μm are separated from the air using the louvre grills 59 and fall into the bins 28, and the air, dusty with small particles with sizes less than 70 μm, enters the sleeve zone. In this case, air passes through the fabric of the sleeves over their entire height, and dust is deposited inside the fabric and on the outer surface of the sleeves. A certain amount of dust particles when rising up and meeting with technological grids 27 installed in the lower part of the sleeves, as a result of impact on the grids also falls into the bunkers, thereby reducing the dust load on the sleeves.

The air cleaned in the sleeves 22 enters their inner part and exits through the open ends of the sleeves into the valve boxes 33.

In the filtering mode (FIG. 6), the purge air holes 17 in the valve boxes are closed by the valves 14, and the holes 18 communicating the valve boxes with the upper cleaned air chamber 61 are open. Therefore, the cleaned air from the valve boxes 33 enters the upper chamber of the cleaned air 61 and then passes through single-row panels 6 of class II air filter cells of the type ФЯК (ФЯК - an air filter that provides effective cleaning of air from particles larger than 1 μm), while obtaining a high degree cleaning, and enters the lower chamber 62 additionally purified air. From the lower chamber 62, the stream of purified air enters the zone of the manifold 7 of the outlet for purified air, bifurcates into two streams in it, which pass successively through the honeycomb grills 67, receiving collectors 70 of variable cross section and enter the nozzles 71 of the collecting tee 72. From the tee 72, the purified air enters the fans 9, which feed it into the discharge recirculation ducts 10, returning the cleaned air to the production room. It is obvious that since in the filtering mode the fans draw air from the filter, the dust collecting chambers 12, 13 of each row of modules are under vacuum.

Moreover, as a result of the fact that the inside of the sleeves is greater than the outside of the sleeves by the resistance value of the equilibrium dusty fabric and pressure losses in the dust layer formed on the outer surface of the sleeves, the fabric, due to the presence of crosses inside the sleeves, is drawn into the sleeves, and the transverse the cross section of the sleeve is in the form of the socket depicted in Fig.7, section EE. The dust collecting chambers will be in the filtration mode, the estimated time controlled by the time relay, after the triggering of which the regeneration of the hose sections begins. Regeneration of the sections of filter bags (cleaning the bags from the dust layer) is carried out sequentially in each separately taken dust collecting chamber by the method of reverse purging of the section of bags with purified air according to an individual cyclogram depending on the initial dustiness of the polluted air in each row of filter modules. At the beginning of the regeneration of the sleeve sections, an additional centrifugal fan 11 is turned on, which draws air from the hopper part 28 of the filter through the bag sections 21 involved in filtering and cleaning it. The air cleaned in the sleeves by means of the fan 11 enters the upper chamber of the purified air 61 and then through the air duct 63 is supplied by the fan 11 to the purge manifold 8.

(где

- сопротивление ткани (тк) фильтрующих рукавов и клапанного (кл) отверстия в расчетной точке «Г» характеристической кривой вентилятора, режимы регенерации (per) и фильтрации (ф).To ensure a given identical performance of the main centrifugal fan 9 at the end of the regeneration mode and the beginning of the filtration mode, having different total network resistances (at the beginning of the filtration mode, the network resistance is less than at the end of the regeneration mode), a controlled throttle valve 76 with resistance is installed in the recirculation duct 10

(Where

- the resistance of the fabric (tk) of the filtering sleeves and the valve (cl) hole at the calculated point "G" of the characteristic curve of the fan, the regeneration modes (per) and filtration (f).

The equalization of the performance of the main centrifugal fan 9 at the calculated point "G" of the characteristic curve of the fan when switching from one operating mode to another is due to the fact that at the beginning of the filtering mode the controlled throttle valve 76 is activated by means of an MEO actuator, thereby creating an additional resistance in the network equal to _{ΔР у.з.} , and at the beginning of the regeneration mode is transferred to the neutral position, reducing the resistance of the network by _{ΔР у.з.}

Next, the cycle of cleaning the sleeve section from the dust layer in any dust collecting chamber (Figs. 3, 4) begins with the valve 14 of the valve box 33 dropping down to close the hole 18, thereby preventing air from leaving the sleeve section 21 to the upper chamber 61 purified air. The movement of the valve 14, which closes the hole 18, leads to the opening of the hole 17, introducing the sleeve section in connection with the purge manifold 8. Since the purge air pressure is greater than the pressure outside the filter bags of the dust collecting chamber, the purge air entering the sleeves creates dynamic air shock, as a result of which the section sleeves are inflated, and the dust layer is separated from the surface of the sleeves and falls down, settling in the hopper 28. In this case, the cross section of the sleeve has the form shown in figure 4 (section B-B). As a result of this reversal of the pressure drop in the sleeves, the latter not only pass from the compressed state to the inflated state, but a reversible air flow is possible through the filter sleeves, which helps to remove dust particles accumulated inside the fabric. After a sufficient interval of time so that the dust separated from the surface of the sleeves falls from the filter bags into the hopper controlled by a time switch, the cleaning cycle is completed and the dust-free section of the bags switches to the filtering mode by raising the valve 14 in order to open hole 18 and close the hole 17. Then, the cleaning cycle of the sections of the sleeves is sequentially carried out according to the described scheme in the remaining dust collecting chambers.

In Fig. 9, by the upper position of five valves 14 in five valve boxes 33 and the lower position of one valve 14 in one valve box 33, the second mode of operation of one row of filter modules is illustrated, in which five sections of the bags are in the filtering mode and one section (the second right) - in cleaning mode.

In the third repair mode of any section of the sleeves, which can be considered using the example of Fig. 3 (the right section), and detected automatically using the differential pressure sensor 60, the operation is carried out in the following sequence. The gateway unloader 44 and the drive of the unloading device 47 are turned off. All hose sections are regenerated, which ensures dust accumulation in the annular groove 42. Then, the shut-off valve 31 of the purge manifold (Fig. 9) goes down and the additional fan 11 turns off, the connection of the purge collector 8 with the upper the chamber 61 of cleaned air, the valve 14 of the faulty hose section is lowered down, blocking the hole 18 for the outlet of the cleaned air.

After the accumulation in the annular groove 42 of a sufficient amount of dust necessary for dust to overlap the partition walls 55 and provide sealing of the faulty sleeve section, the shutter 36 is rotated clockwise, which closes the hole 29 for introducing contaminated air into the hopper 28, providing final sealing of the faulty hose sections.

After that, the inspection hatch 37 opens. Then, using a portable blower, a faulty sleeve is detected, it is dismantled and replaced with a new sleeve. After that, the inspection hatch 37 closes, and the valve 31 of the purge manifold 8, the valve 14 and the flap 36 of the repair section of the sleeves are returned to their original position. Then, the drives of the gateway unloader 44 and the unloading device 49 are turned on. In the repair mode, the throttle valve 76 with the MEO actuator is in the same position as in the regeneration mode.

Mechanical impurities (wood grinding dust), separated from the air using louvres 59 and dust collecting chambers 12, 13 and falling into the hoppers 28 of each row of modules, after interacting with a rotating unloading device 49 of a conical-cylindrical shape enter the annular grooves 42 of the cylindrical part 39 hoppers and then rotating blades 51 are removed through the discharge openings 30 in the bottoms of the troughs to the sluice unloaders 44, which feed them through a tee 79 to the pressure pipelines 80 of closed air ansportnoy installation 81 for centralized collection of solids having a fan 82 and a cyclone 83 which is discharged into the hopper 84. Aeration 102 and exhaust 103 provide general ventilation air balance in the shop.

According to the passport data, filters of the type FJAK of class F7 (EU7) and F8 / 9 (EU8 / 9) are recommended to be operated respectively in the resistance range of 100 ... 350 Pa and 120 ... 450 Pa. The resistance of the filter 6 is measured by the sensor 78 as the pressure difference between the lower chamber 62 of the additional purified air and the upper chamber 61 of the purified air. When the maximum pressure value H = 350 Pa in the F7 (EU7) filter or H = 450 Pa in the F8 / 9 (EU8 / 9) filter is reached, an audible signal sounds, notifying that it is necessary to replace filters 6 with clean ones.

Regeneration of the pockets of cell filters is carried out by washing them in water with compression by hands and does not cause large operating costs.

In the fourth mode (dust-air mixture explosion in the collection pipe 87 of the aspiration pneumatic conveying system), illustrated in Fig. 11, the filter mechanisms work automatically in the following order. An optical flame detector 88 detects the occurrence of a flame or spark in conduit 87 and sends an electrical signal through an amplifier 89 to the shutoff valve 92 to open it, the shutoff valve 94 to close, the main centrifugal fan 9 to turn off, and turns on an audible signal to stop the operation of machine equipment.

Valve 92 is actuated by an electric detonator. When the valve 92 is opened from the cylinder 91, a fire extinguishing agent such as ammonium phosphate is fed into the pipe 87 through the nozzle 93. In the cylinder, the extinguishing agent is under pressure of compressed nitrogen (1-1.2) · 10 ⁵ kPa. Getting into the pipeline with a combustible medium, the extinguishing agent inerts the unburned mixture and extinguishes the flame in the area of the explosion suppressor 90.

After extinguishing the flame in the collection pipe, the inspection hatch 95 opens under the explosion suppressor 90, the pipe is cleaned of combustion products, then the inspection hatch 95 is closed, the shut-off valve 92 is closed and a new electric detonator is inserted into it, the empty cylinder is replaced with a new cylinder 91 with a fire extinguishing substance, the shut-off valve 94 opens, the fan 9 and a sound signal are turned on, allowing to continue working on the machine equipment.

In the fifth mode (explosion of the dusty air mixture directly in the filter), which can be considered using the example of Fig. 9, the filter mechanisms work automatically in the following sequence.

An optical flame detector 100 detects the occurrence of fire in the hopper part of the filter and sends an electric signal through an amplifier 99 to the shutoff valve 98 to open it, as well as shutdown signals: to the gate unloader 44, the conical-cylindrical unloader 49 and the main centrifugal fan 9 and turns on the sound signal on the termination of the operation of machine equipment. Valve 98 is actuated by an electric detonator. When opening the valve 98 in the upper part of the hopper 28, the upper chamber 61 of purified air and the lower chamber 62 of additional purified air is supplied through fittings 97 extinguishing inert gas such as a gel-hydrocarbon mixture, which provides fire extinguishing in the filter.

In the explosion of the dust-air mixture due to the blast wave, six bursting membranes 96 are simultaneously opened and the flame spreads to the area of the collection pipe 87 and the cleaned air output manifold 7. In the collection pipe 87, the fuse breaks and the fire retardant valve 101 closes automatically (FIG. eleven). In the collector 7 of the outlet for purified air, further advancement of the fire into the recirculation duct 10 is prevented by the honeycomb grilles 67, which perform the function of fire barriers.

All of the above, including a description of the operation of the filter, confirms the possibility of using it in industry with obtaining high technical performance in comparison with the known filter designs. In addition, both in the sources of patent and scientific and technical information, and in industry, such a design did not occur, which indicates that the proposed solution meets the criteria of the invention.

Claims (1)

Bag filter for three-stage air purification from mechanical impurities, containing at least one row of filtering modules, each of which has two dust collecting chambers installed with an interval between their side walls, equipped with tube sheets in the upper part with through pipes and sections of vertically arranged filtering of sleeves fixed with upper open ends to the pipes of the tube sheets, a collector of variable cross-section for the input of contaminated air, placed in between dust collecting chambers, a purified air outlet manifold, a purge air manifold equipped with a shut-off valve at the inlet, a main centrifugal fan installed at the front end of each row of modules, and a recirculation duct, valve boxes mounted on tube sheets with poppet type actuating valves, interacting alternately with two coaxial holes for purge and purified air located on the horizontal axis of the purge air manifold and one above the other in each valve box, and two mirror-mounted valve boxes of one module have a common partition separating their pairs of coaxial holes, a sealed service chamber mounted on the valve boxes, a hopper made of three parts, the upper of which is square, and lower cylindrical shape, in the upper part of the hopper there are openings for the input of contaminated air, equipped with guide shields, a louvred sieve is installed obliquely under each dust collecting chamber a, and the lower cylindrical part of the hopper is made in the form of an annular groove with an opening for unloading mechanical impurities into the airlock unloader with the arrangement of airlock unloaders in adjacent rows of modules in a checkerboard pattern, a conical-cylindrical-shaped drive unloading device with blades is installed over the groove along the axis of the cylindrical part, fixed radially on the outer surface of the cylindrical part and lowered into the groove, in addition, the filter contains at least one single-row panel of air cells new filters, and the purge air manifold is equipped with an additional centrifugal fan, the discharge pipe of which is connected to the inlet of the purge air collector, characterized in that the panel of cell air filters is installed horizontally in the gap between the dust collection chambers under the valve openings for purified air along the entire length of a series of modules with the formation of the upper chamber of purified air, which is connected to the suction pipe of an additional centrifugal valve core, and the lower chamber of additionally cleaned air, made with one open end, to which a cleaned air outlet manifold is attached, protruding beyond the range of modules, having two vertical side walls with rectangular windows, in which cellular gratings are made of flat and corrugated ribbons heat-resistant material having a total living cross-sectional area, ensuring the prevention of the passage of fire through them with the installed performance of the main centrifugal fan, in addition, receiving collectors of variable cross section are connected to the purified air outlet manifold at the outlet of the honeycomb lattices, the outlet openings of which are connected to the nozzles of the collecting tee connected at the outlet to the suction nozzle of the main centrifugal fan.

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