US1558663A - Assionobs to combustion enoineebing cobpoba - Google Patents

Description

Oct; 27, 1925.

- J. E. BELL ET AL FUEL PULVERIZING APPARATUS Filed Sept. 1 1922 z s'heats-heot -1- v WITNESS flan/69W.

ATTORNEYS Oct. 27, 1925. V

J. E. BELL ET AL 'FUEL PULVERIZING APPARATUS Filed Sept, 16, 1922 i 2 sheets-sh; 2

WITNESS A TTORNEY-S Patented Oct. 27, 1925.

UNITED STATES PATENT orrlca.

JOHN E. BELL, or BROOKLYN, NEW roan, AND HENRY xmsmena, or rrr'rs- BURGH PENNSYLVANIA, ASSIGNORS T0 COMBUSTION TION, A CORPORATION OF NEW YO'RK.

ENGINEERING CORPORA- FUEL-PULVEBIZING APPARATUS.

Application filed September 16, 1922. Serial No. 588,583.

To all whom it may concern:

Be it known that we, JOHN E. BELL and HENRY KREIsINGER, citizens of the United States, residing at Brooklyn, in the county.

of Kings and State of New York, and at Pittsburgh, in the county of Allegheny and State of Pennsylvania, respectively, have invented certain new and useful Improvements in Fuel-Pulverizing Apparatus, of which the following is a specification.

. Our invention relates to fuel pulverizmg apparatus and systems, particularly those employing air for carrying away the pulverized or powdered fuel from the grinder or pulverizer. Our principal aim is to ob- .viate undesirable moisture in pulverized fuel, such as powdered coal. How this and other advantages can be realized 5 through our invention will appear from our description hereinafter of the best ways of carrying out the invention knownto us.

In the drawings, Fig. 1 is a somewhat diagrammatic side view of a system of apparatus convenient for the purposes of our invention.

Fig. 2 is a similar view of a simplified apparatus.

The system shown in Fig. 1 comprises a lpulverizing grinder 5 (shown as of well nown type) which receives coal to be powdered at an intake 6. As this coal is brought ,to a sufficiently fine state of division in the grinder 5, it is picked up by a current of carrying air and conveyed away through a delivery conduit 7 From this aerating pulverizer 5, the air-borne fuel is received by an unloading se arator 9 (to whose upper end the conduit is tangentially connected at 10), here-shown as of the centrifugal funnel or cone type. The powdered coal slidi g down the funnelsides to the discharge pipe] 11- at the bottom may be led off to a storage bin, a feeder, etc. (not shown). The separated air passing up and out of the separator 9 through the central air outlet 12 may be returned to the air intake 13 of the pulverizer 5 (to serve again as carry ing air) through a conduit 14,-here shown as including or connected to various means for the abstraction of moisture.

The necessary flow or current of carrying air for conveying the fuel (and, in t e system here shown, for returning the air fromthe separator 9 to the pulverizer 5) may be created in various ways, as by means of an electric motor driven rotary centrifugal blower 15, which may be connected in the conduit 7 with its suction side toward the pulverizer 5 and its discharge side toward the separator intake '10. x

In practice, both the coal to be pulverized and the atmospheric 'air used to carry it will, always contain varying percentages of moisture. While moisture in moderate amounts (say 13% of the coal, for example) is not detrimental to grinding (but rather, indeed, favors fine pulverization), even moderate amounts of moisture may interfere-with the subsequent handling and use of the coal quite seriously. It is desirable, therefore, to preheat the carrying air somewhat (say to 130 F.) before it enters the aerating pulverizer 5 (especially during the winter months, when the percentage of moisture in the coal is usually excesslve, and the absorptive capacity of the air is low, owing to the low-temperatures of F. or under then prevalent), so as to give the air ample capacity for taking up moisture from the of which a heating medium (such as-steam' or hot water) may be circulated or assed through the tubes 17. When the air 1s thus heated on the way to the pulverizer 5, it is desirable to thermo-insulate the separator 9 with a suitable covering or lagging,-as indicated at 20, for otherwise the coolin of its sides by the. surrounding atmosp ere would condense and precipitate considerable moisture from the warm carr ing air,-to run down and wet the fuel again on its wa I to the outlet 11. As stated above, a mo erate amount of moisture in the. coal is favorable to fine grinding; i. e., undried coal comes from the grinder in a finer state than does coal that haspreviously been dried. This seems to be partly because the particles are heavier when moist, and hence are not lifted by the air till they become finer, and partly because the mixture of air and water vapor decreases in specific gravity and lifting power as the moisture in the air increases When the same body of carrying air is continually circulated in a closed circuit (as in Fig. 1), fairly moist coal will soon saturate it. In order to obviate this and maintain the absorptive capacity'of the air, however, moisture may be-a-bstracted from the return side of the system, after the air has been unloaded of its fuel content. One way of eliminatin such moisture is by means of a condensing cooler 24 interposed in the conduit 14 ahead of the heater 16. As shown, this cooler 24 has a casing (like that of the heater 16) enclosing a bank of U tubes 25 having inlet and outlet headers and connections 26, 27 through which cooling water can be passed or circulated, and also a draw-oft pipe 28 from its bottom for water of condensation. The returning air passing through the condenser 24 on the. way to the heater 16 may be so chilled as to lose all the moisture previously taken up from the coal; but its temperature and absorptive capacity are fully restored in the heater. As shown, the air leaves the con denser casing just above its conical lower end, and the ensuing portion of the conduit 14 has an upward bend 29 that serves as a dam to insure against flooding of the heater. by sudden condensation of large amounts of water.

Moisture may also (or alternatively) be eliminated by discharging part of the moisture-laden, coal-free air on the way from the separator 9- to the heater 16. As shown, provision is made for doing this by means of an upright vent pipe 30 havinglateral connection 31 with one side of the U bend of the conduit 14, just beyond the .separator 9. The moisture-laden air thus discharged may be replaced with drier outside air, so as to meet the carrying requirements of the system with air having a less total moisture content than that leaving the separator 9. For such replacement, use may be made of a damper-controlled air intake 33 entering the conduit 14 beyond the condenser 24, on the-way to the heater 16, so that this make-up air shall be preheated before entering the pulverizer 5. In addition (or alternatively), some outside makeup air may be admitted at 6 along with the fuel.

In order that water condensing in the vent 30 (as a result of atmospheric cooling) may not drain back into the conduit 14, the latter may be extended down below the lateral connection 31 and provided with a drainage outlet 34.

In order to comply with sanitary regula tions, it may be desirable to eliminate from the air discharged at thevent 30 any residue of solid particles that may remain in it after it leaves the separator 9. This can be done by passing the air through a condenser 35, so that the fine particles may serve as nuclei, for the precipitated drops of water, and thus be pulled down by them, so to speak. As shown, this condenser 35 has the form of a hood-like chamber over the end of the discharge pipe 30, above the roof 36. The walls of the hood are cooled and chilled by the surrounding atmosphere, and the water thus precipitated in the hood falls (or trickles down the walls) into a pan 37 beneath,.the air finally escaping through the annular opening 38 under the lower-edge of the hood. The water in the pan 37 may drain or be drawn off through the outlet 39, and the coal can be removed from the pan and thus recovered.

The system or apparatus illustrated in Fig. 2 differs from that of Fig. 1 in omitting the condenser 24, and relying entirely on the partial replacement of the moisture-laden separated air for. eliminating moisture from the return side of the system. This apparatus can be operated satisfactorily bydischarging about two-sevenths of the moistore-laden carrying air at the vent 30, and taking in an equal amount of fresh makeup air, half at the damper-controlled air intake 33 on the way to the heater 16, and the other half at the coal intake 6. The

separator 9 may, of course, be thermo-in-- sulated to advantage as indicated at. 20, just as in the apparatus of Fig. 1.

In Fig. 2, the various parts and features.

are all marked with the reference numerals denoting corresponding parts and features in Fig. 1, as a means of dispensing with merely repetitive description.

That we claim is 1. A fuel pulverizing system comprising an aerating pulverizer, an air and fuel sepa-- rator receiving air-borne fuel from said pulverizer and returning the separated air there to, means for heating the returning air, and means for abstraction of moisture from the .return side of the system on the way to said fuel from said pulverizer and returning the 4 separated air thereto, means for heating the returning air, vent means for discharging a means for discharging part of the moisture-' 5. Fuel pulverizing apparatus comprising an aerating pulverizer, an air and fuel separator receiving air-borne fuel from said pulverizer and returning the separated air thereto, condenser means for eliminating moisture from the returning air, means for heating the air on its way from said condenser means tosaid pulverizer, so as to maintain the capacity of the circulating air for taking up moisture from the fuel, and

laden air on the way from the separator to the condenser means, and for admitting drier air in lieu thereof.

'6. Fuel pulverizing apparatus comprising an aerating pulverizer, an air and fuel separator receiving air-iborne fuel from said pulverizer and returning the separated air thereto, condenser means for eliminating moisture from the returning air, and means for heating. the air on its wa from said condenser means to said pulverizer, so as to maintain the capacity of the circulating air for taking up moisture from thefuel.

7. Fuel pulverizing apparatus'com rising an aerating pulverizer, an air and fue separator receiving air-borne fuel from said pulverizer and returning the separated air thereto, condenser means for eliminating moisture from the returning air, means for heating the air on its 'way from said condenser means to said pulverizer, so as to maintain the capacity of the circulating air for taking up moisture from the fuel, and means for discharging part of the moistureladen air on the way from the separator to the condenser means.

8. Fuel pulverizing apparatus comprising an aerating pulverizer, an air and fuel separator receiving air-borne fuel from said pulverizer and returning the separated air thereto, condenser means for eliminating moisture from the returning air, means for heating the air on its we laden air on the way from the separator tothe condenser means, with a condensing disparticles from the air from said condenser means to said pu verizer, so as to charge hood for eliminating any residue of solid particles from the air discharged.'

9. A fuel pulverizing system of the closed type comprising an aerating pulverizer, an air and fuelseparator receiving air-borne ,fuel from said pulverizer and returning the separatedair thereto for recirculation, and means for abstractionof moisture from the return side of the system.

10. A fuel pulverizing system comprising an aerating pulverizer, a. thermo-msulated air and fuel separator receiving airborne fuel from said pulverizer and returning the separated air thereto, and means for abstraction of moisture from the return side of the system.

11. A fuel pulverizing system of the closed type comprising an aerating pulverizer, an air and fuel separator receiving air-borne fuel from said pulverizer and returning the separated air thereto for recirculation, and means for replacing part of the moisture-laden returning air 'with drier air.

12. A fuel pulverizing system of the closed type com rising an aerating pulverlzer, an air and fuel separator receiving airborne fuel from said pulverizer and return ing the separated air thereto for recirculation, and means for dischar ing part of the moisture-laden returning air and. for admitting outside air to carry the fuel in lieu thereof.

13. Fuel pulverizing apparatus comprising an aerating pulverizer, means for heating-carryin air for said pulverizer, and a thermo-insu ated air and fuel separator receivin air-borne fuel from said pulverizer.

14. uel pulverizing apparatus comprising an aerating pulverizer, and a thermoinsulated unloading separator receiving air- I borne fuel from said pulverizer.

15. Fuel pulverizing apparatus comprising an aerating pulverizer, a thermo-msulated unloading separator receiving airborne fuel from said pulverizer, and discharge vent 'means for moisture-laden air with means for eliminating any residue 0 solid'particles from the air dlscharged at said vent.

16. Fuel pulverizing apparatus com rising an aerating pulverizer, means for eating carrying air for said pulverizer, an 1111- loading separator receiving air-borne fuel from said pulverizer, and discharge vent means for moisture-laden air, with a condensing discharge hood for eliminating any residue of solid particles from the air discharged.

I testimony whereof, we have hereunto signed our names.

JOHN E. BELL. HENRY KREISINGEB'.

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