CS212747B2 - Apparatus for safe manipulation of powdered coal - Google Patents

Abstract

1508494 Preventing coal dust explosions ARMCO STEEL CORP 21 May 1975 [17 June 1974] 21826/75 Heading A5A [Also in Division B2] A system for the safe handling of pulverised coal comprises: loading means 11 for feeding raw coal into the system; pulverising means 12, 14 to grind and heat lump coal received from the loading means to a dry powder condition; separator means 16 to divide out the fines; a coal powder storage tank 17; filter means 29, 21 to collect the fines; first duct means 15 connecting the pulverising means to the separator means; second duct means 18 connecting the separator means directly to the storage tank; third duct means 19 connecting the separator means to the filter means; fourth duct means 22, 23 connecting the filter means to the storage tank; a plurality of explosion detectors (positioned as shown); a plurality of explosion extinguishers (also as shown); means interconnecting said explosion detectors and said explosion extinguishers so that when pressures above normal operating pressures develop said explosion extinguishers will be actuated; a said explosion detector in association with said pulverising means and a said explosion extinguisher for discharging explosion suppresion agent into acid pulverising means; a said explosion detector in association with said separator means and a said explosion extinguisher for discharging explosion suppression agent into said separator means; a said explosion detector in association with said filter means and a said explosion extinguisher for discharging explosion suppression agent into said filter means; and means interconnecting said explosion detectors with said loading means, said pulverising means, and said separator means so that when said explosion extinguishers are actuated said loading means, said pulverising means and said separator means are simultaneously in activated to shut down the system.

Description

The present invention relates to an apparatus for safely handling pulverized coal in a pulverized coal pulverizing system, drying pulverized coal and collecting it in an oxidizing atmosphere that could cause a pulverized coal explosion or fire. In this treatment, bag filters are used which are particularly susceptible to explosion or fire because the pulverized coal may accumulate and spontaneously ignite.

Until now, coal pulverization has been carried out without fire or explosion protection. Most often, finely divided coal was fed directly into the burners or into the combustion chambers. The conveying air was used as all or part of the combustion air needed to burn coal. Obviously, in such a use of pulverized coal, premature ignition cannot cause an explosion if the conveying air velocity is greater than the rate of fire propagation in pulverized coal. The burning particles are simply blown into the combustion chamber. However, they may enter · bag filters or storage containers where the risk of explosion or fire is not excluded. SUMMARY OF THE INVENTION It is an object of the present invention to provide a pulverized coal handling device so as to eliminate this danger.

The present invention relates to an apparatus for the safe handling of pulverized coal in a pulverizing, pulverizing, drying and re-collection system comprising a raw material feed loader, a pulverizer for grinding and a heating of lump coal from a dry powder loader; a pulverized coal storage tank, filters, a first conduit connecting the crusher to the separator, a second conduit connecting the separator directly to the storage vessel, a third conduit connecting the separator to the filters, and a fourth conduit connecting the filters to the storage tank. a second explosion detector closely coupled to the pulverizer output, a first, second, third and fourth flame extinguisher connected to the pulverizer and the pulverizer output, third and fourth explosion detectors closely coupled associated with a separator, fifth and sixth explosion extinguisher, coupled to a fifth, sixth, seventh and eighth explosion detector, closely coupled to filters, and to the seventh to twelfth explosion extinguishers associated with the filters.

In a preferred embodiment of the apparatus of the present invention wherein the separator is a cyclone separator, the filters are bag filters, the third conduit is branched into two branches each leading from said cyclone separator to a respective bag filter, the first explosion detector is located near the pulverizer. the second and third explosion detectors are located in the first conduit, one to the pulverizer and the second at the cyclone separator, the fourth explosion detector is located in the third conduit near the cyclone separator, the fifth and sixth explosion detectors in each of said branches of the third conduit; a seventh detector and an eighth detector in each of said bag filters, and wherein the first anti-explosion fire extinguisher is located at and oriented towards the pulverizer, the second anti-explosion fire extinguisher, the third anti-explosion fire extinguisher and the fourth anti-explosion fire extinguisher the apparatus is located in the first pipe and is oriented towards the pulverizer, the fifth anti-explosion extinguisher is placed in the third pipe and is oriented towards the cyclone separator, the sixth anti-explosion extinguisher is placed in the cyclone separator, the seventh and eighth from the two branches of the third pipe and are directed to the bag filters, the ninth anti-explosion extinguisher and the tenth anti-explosion extinguisher in one of the bag filters and the eleventh and twelfth anti-explosion extinguishers in the second bag filter.

In comparison with the prior art, the invention allows a double fire and explosion protection to ensure safe handling in a pulverized coal pulverizer, its drying and re-collection. Moreover, the interconnection of the fire and explosion protection system ensures its operational efficiency.

The pulverized coal safety device of the present invention can be used as an accessory for pulverized coal injection into a blast furnace. Likewise, the invention can be used in a coal gasification plant.

The invention is explained in more detail in the following description by way of example with reference to the accompanying drawing, in which the arrangement of the individual explosion and fire suppression elements in the device according to the invention is schematically illustrated.

In the figure, a bunker 10 for storing the raw coal is provided, which is provided with a hopper 11 for introducing the raw coal into the pulverizer 12 through the first line 13. At the hopper outlet there is a coal feed regulator 13a for regulating the conveyed quantity. A fan 14 is connected to the pulverizer 12, through which hot air is blown into the pulverizer 12.

At the outlet of the pulverizer 12, through which the pulverizer exits pulverized coal, a second line 15 leading to the cyclone separator 16 is connected. Typically about 90% of the coal powder supplied to the cyclone separator 16 is discharged via line 18 directly to the storage tank 17. representing the remaining 10% of pulverized coal entering the cyclone separator 16 extends therefrom through a third conduit 19 and its extensions into a pair of bag filters. The wall thus separated and collected in the bag filters 20, 21 is discharged from these filters via lines 22, 23 into the storage tank 17.

The invention is intended to protect the described part of a pulverized coal handling device from explosion damage or coal dust fire. What happens to coal after it has accumulated in the storage tank 17 is not essential to the invention. For example, the pulverized coal is removed from the storage tank 17 via conduits 25 to other storage tanks 26, 27 which are connected at the outlet side to a discharge conduit 28, 29 leading to a location not shown, for example for blowing into a blast furnace. The pulverized coal can also be discharged from the supply tank 17 via a line 30 to a further tank 31 which is connected to a gasification plant (not shown).

In the pulverization of the coal carried out by the apparatus described above, the relatively wet lump coal is fed from the bunker 10 through the hopper 11 to the pulverizer 12. The pulverized coal is conveyed by overpressure from the pulverizer 12 further through a second line 15, usually 75 cm in diameter. meters, to the cyclone 16 for further processing. The outlet side of the cyclone separator 16 is connected to two bag filters 20, 21 forming tube collectors that can be located approximately 1 m from the top of the cyclone separator 16. Although a pressurized system is described herein, it will be apparent to those skilled in the art that vacuum transport can also be used.

The protection provided by the device according to the invention starts at the pulverizer 12 and covers the pipe connection to the outlet of the cyclone separator 16 and to the two bag filters 20, 21 for collecting the flour.

The detecting portion of the apparatus for detecting an explosion is formed by pressure-sensitive explosion detectors, namely a pressure wave, which would be generated in an explosion. · The detector * actuated · closes the electrical · circuit of the power unit · to start a rapidly emptying fire extinguisher, which is electrically connected to this power unit. The first explosion detector 32 is located at the point of exit of the second conduit 15 from the pulverizer 12. However, it may also be about 30 cm away from the pulverizer 12. The second explosion detector 33. it is also located in the second conduit 15, but at a greater distance cd of the pulverizer 12, typically about 9 m.

The third detector 34 is located near the upper end of the second conduit 15, about 30 m from the pulverizer 12. The fourth detector 35 is located in the third conduit 19 of the cyclone separator 16. The fifth and sixth detector 36 and 37 are The seventh and eighth explosion detectors 38, 39 can be located in the bag filters at their inlet and on the basis of the filter housing.

For explosion suppression, anti-explosion fire extinguishers are strategically placed in the device, responding to pulses from the explosion detectors. The first fire extinguisher 40 is located above the pulverizer 12 and releases its extinguishing agent downwardly through the second conduit 15 and into the pulverizer 12. The content of this quick-discharge anti-explosive fire extinguisher is about 10 liters. The second anti-explosion fire extinguisher 41, also capable of being rapidly emptied, is located somewhat further from the pulverizer 12 and is oriented to release its extinguishing agent into the second conduit 15 and towards the pulverizer 12. Its content is, for example, 5 liters of extinguishing agent.

The third and fourth anti-explosion fire extinguishers 42, 43 are located at the top of the end of the second conduit 15 and are also oriented to discharge their extinguishing agents directly into the second conduit 15 and downwardly toward the pulverizer 12. Their content is, for example.

To protect the cyclone 16, a fifth fire-extinguishing extinguisher 44, mounted on its top behind the mouth into the third conduit 19, can be protected. Its contents may be 5 liters, for example, and the extinguishing agent discharges therefrom rapidly into the cyclone. in the circulating air. The sixth explosion extinguisher 45 is located at the third conduit 19 of the cyclone separator 16, and releases its agent downwardly into the interior of the cyclone separator 16. Its content is, for example, 5 liters.

The seventh and eighth anti-explosion fire extinguishers 46, 47 are located at branches 19a, 19b leading to bag filters 20, 21. These anti-explosion fire extinguishers are adapted to release their reagents to branches 19a, 19b down into bag filters 20, 21 and their filters. capacity is 5 liters. Further, in the hopper of each of the bag filters 20, 21 is located one additional anti-explosion fire extinguisher, namely the ninth and tenth anti-explosion fire extinguishers 48, 49. These anti-explosion fire extinguishers 48, 49 are mounted below the hopper level to release its reagents into the respective hoppers by a set of atomizing nozzles that atomize the reagent in a cone with a 120 ° apex angle. Their content is 10 liters.

For further protection, eleventh and twelfth anti-explosion fire extinguishers 50, 51 are arranged at the bottom of the bag filters, arranged to discharge their contents into the corresponding filter. Their contents are 30 liters. These fire extinguishers 50, 51 can also be used for fire suppression.

The extinguishing agent used in the twelve fire extinguishers 40-51 is bromochloromethane or the like. The mechanism by which these agents act may be chemical inhibition. Since combustion is believed to be a chemical reaction, it depends on certain radicals in the area before the flame that their chains branch out to promote the progression of the flame front. Halogenated hydrocarbons such as bromochloromethane and bromotrifluoromethane regulate these radicals to terminate the chains.

Fire protection devices, including carbon dioxide fire extinguishers, are positioned in the apparatus so that, after the impulses have been emitted from the fire detectors, the fire extinguisher can be emptied towards those parts of the device according to the invention which are particularly sensitive to fire hazards. .

For this purpose, a first fire detector 61 is disposed in conjunction with the pulverizer 12. A second fire detector 62 is associated with the cyclone separator 16 via its third conduit 19. The third and fourth fire detectors 63, 64 are arranged in conjunction with bag filters 20, 21. These four fire detectors 61, 62, 63, 64 protect the main part of the pulverized coal handling equipment from fire by means of the corresponding fire extinguishers to which they are connected. However, it is desirable to provide fire protection in downstream parts as well. For this reason, in the storage tank 17, a fifth and a sixth fire detector 65, 66 are located, which can detect fire in both the tank 17 and the downstream tanks 26, 27 and 31.

The fire detectors controlled by the fire detectors are located as follows: The first, second and third fire extinguishers 71, 72, 73 are connected to the pulverizer 12. The fourth fire extinguisher 74 is connected to the cyclone separator 16. Four other fire extinguishers 75, 76, 77 and 78 are The ninth, tenth and eleventh fire extinguishers 79, 80, 81 can be associated with tank 17, while downstream tanks 26, 27, 31 are in communication with the last three fire extinguishers 82, 83, 84.

The fire suppression and fire extinguishers are connected to the aforementioned explosion and fire detectors in a known manner. It is further understood that the detectors 32 and 39 and the fire detectors 61 to 66 are also connected to the actuators of the unit.

Claims (2)

SUBJECT 1. An apparatus for the safe handling of pulverized coal in a pulverized coal pulverizing, drying and re-collection system comprising a raw coal feed loader, a pulverizer for grinding and heating lump coal from a dry powder loader, a flour separator, a tank for pulverized coal storage, filters, a first conduit connecting the crusher to the separator, a second conduit connecting the separator directly to the storage vessel, a third conduit connecting the separator to the filters, and a fourth conduit connecting the filters to the storage tank, characterized by having first and second detectors (32, 33), closely coupled to the outlet (15) of the pulverizer (12), the first, second, third and fourth anti-explosion fire extinguishers (40, 41) of the pulverized coal handling device, so that O dstaveno. Since pulverized coal can also ignite due to the presence of metal in the coal, the metal rubs against the metal pipes and other elements of the apparatus, so that sparks occur. It is therefore expedient to place magnets for retaining magnetic metals in certain areas of the apparatus prior to entering the pulverized coal handling apparatus. As an example, a magnet 90 located at the top of the bunker 10 is shown in the drawing. When setting the detectors, the normal pressure level is first determined in the device. The eight blast detectors 32 to 39 are then set to be pressure sensitive slightly higher than normal operating pressure. If higher pressure is generated when handling pulverized coal, anti-explosion extinguishers are activated. Similarly, the normal operating temperature is predetermined and the six fire detectors 61-66 are set to a slightly higher temperature. If this temperature is exceeded during operation, the corresponding fire extinguishers are activated. In a preferred arrangement, these fire extinguishers are in operation to eliminate the source of ignition, thus preventing both an explosion and extinguishing the fire. In such an arrangement, it is expedient for the explosion suppression system to be switched off by actuating the fire detectors and corresponding fire extinguishers, so as to avoid the need to refill unnecessarily emptied firefighting extinguishers. In any case, the operator may do so manually if circumstances permit. In order to ensure a particularly high degree of safety, it is also expedient to place fire-extinguishers manually in the equipment. In the illustrated embodiment, three such fire extinguishers 91, 92, 93 are provided, one in conjunction with the bunker 10, one with the storage tank 17 and one with the adjacent tanks 26, 27 and 31. vynalezu 42, 43) connected to the pulverizer (12) and the outlet of the pulverizer (12), the third and fourth explosion detectors (34, 35), tightly coupled to the separator (16), the fifth and sixth anti-explosion fire extinguishers (44, 45), connected to a separator (16), a fifth, sixth, seventh and eighth detector (36, 37, 38, 39), closely coupled to the filters (20, 21) and a seventh to twelfth fire extinguisher (46, 47, 48, 49) , 50, 51) connected to the filters (21, 20). 2. Apparatus according to claim 1, wherein the separator is a cyclone separator, the filters are bag filters, the third pipe is branched into two branches, each of which leads from said cyclone separator to the respective bag filters, characterized in that the first explosion detector ( 32) is located close to the crusher (12), the second explosion detector (33) and the third explosion detector (34) are located in the first conduit (13), one towards the pulverizer (12j and the other at the cyclone separator (16)). the fourth detector (35) is located in the third conduit (19) near the cyclone separator (16), the fifth detector (36) and the sixth detector (37) in each of said third conduit taps (19a, 19b) (19), and a seventh explosion detector (38) and an eighth explosion detector (39) in each of said bag filters (20, 21), and wherein the first anti-explosion fire extinguisher (40) is located at the The second anti-explosion extinguisher (41), the third anti-explosion extinguisher (42) and the fourth anti-explosion extinguisher (43) are located in the first conduit (13) and are oriented to the grinder (12). towards the pulverizer (12), the fifth anti-explosion extinguisher (44) is located in the third conduit (19) and is oriented towards the cyclone separator (16), the sixth anti-explosion extinguisher (45) is located in the cyclone separator (16), the seventh anti-explosion the fire extinguisher (46) and the eighth anti-explosion extinguisher (47) are each located in one of the two branches (19a, 19b) of the third conduit (19) and are oriented towards the bag filters (20, 21), the ninth anti-explosion extinguisher (48) and a tenth anti-explosion extinguisher (49) in one of the bag filters (20) and eleventh and twelfth anti-explosion extinguishers (50, 51) in the second bag filter (21) .