US3033545A - Firing apparatus for kilns - Google Patents

Description

May 8, 1962 Filed Oct. l, 1959 PRE.- HEATING 'l CALCINING FINISH COOLING V. J- AZBE FIRING APPARATUS FOR KILNS C5 Sheets-Sheet 1 May 8, 1962 v. .1. AzBE 3,033,545

FIRING APPARATUS FOR KILNS Filed OCT.. 1, 1959 5 Sheets-Sheet 2 May 8, 1962 v. J. AzBE FIRING APPARATUS FOR KILNS 3 Sheets-Sheet 3 Filed oct.

Unite 3,033,545 FERING APPARATUS FR KHLNS Victor J. Azbe, Webster Groves, Mo., assigner to Aabe Corporation, Clayton, Mo., a corporation ot' Missouri Filed Oct. 1, 1959, Ser. No. 843,713

3 Claims. (Cl. 263--29) calcining kilns wherein heavier, lower-cost oils may beV used; the provision of means for reliably vaporizing, gasifying and effectively distributing the. oil to be red by the use of hot air from the kiln cooler and hot recirculating gases high in CO2 from the preheating Zone of the kiln, blending these to favor Boudouards reaction of C+CO2=2CO; and the provision of firing means of the class described demanding a less critical CO2 concentration in the kiln gasification chamber. Other objects and features will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

FIG. l is a diagrammatic vertical section of a typical kiln to which the invention may be applied;

FIG. 2 is an end view of firing apparatus for the kiln of FIG. l; Y

FIG. 3 is a vertical section taken on lines 3-3 of FIGS. 2 and 4; and,

FIG. 4 is a cross section taken on line 4-4 of FIG. 3.

Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

Heretofore, and as shown in said patent, fuel oil has been introduced into calcining kilns through a firing nozzle, along with hot recirculating gases rich in CO2 obtained from the kiln above its calcining zone. The purpose of introducing the hot recircula'ting gases with oil spray from the firing nozzle was to effect vaporization, hydrocarbon cracking and gasification action upon the oil as explained in said patent, whereby a desirable coinbustion condition was obtained when the vaporization and gasification residuals met with the air in the kiln for combustion purposes among its charge of partially burned lime. While the results thus obtained were generally satisfactory, they depended upon a proper temperature of recirculating gases. This temperature is not always easy to maintain at a desired value. Thus sometimes such recirculating gases do not come ofI from the kiln hot enough to vaporize the oil correctly and particularly not oil'of high viscosity resulting in subsequent poor gasification conditions. By means of the present invention the 'required critical gasification temperature is easier to maintain by use of more constantly generated heat at' or above the critical vaporizing temperature acquired by air passing through the cooler of the `kiln and by partial combustion of oil with the oxygen of this air. This results in a more reliable attainment of the critical gasifying temperature required for the many reactions occurring when States atent @t Patented May 8, 1962 ice 2 combining with the recirculating gases, which later are all used for injection purposes.

rReferring now more particularly to FIG. l, there is shown at numeral 1 a hollow calcining kiln shaft having a charging means 3 at its upper end. In its lower portions, the shaft contains a wall 5 dividing the shaft 1 into transverse sections 7 and 9. The lower ends of the sections 7 and 9 have the vusual material discharge means 11, including conventional means 13 for introducing primary air into the sections 7 and 9. The air is introduced from a fan or blower 15 having a fresh air inlet 17. Control of the amount of air introduced into the sections 7 and 9 from the blower 15 is obtained by means of an adjustable orice f19.

The shaft 1 contains a preheating zone 21, a calcining zone 23 and a cooling Zone 25. The preheating zone is determined by upper gas outlet ports 27 and lower gas outlet ports 29, the latter also determining the upper limit ofthe calcining Zone 23. The calcining zone 23 is divided into a calcining Ifinishing combustion zone 31, a radiant calcining combustion zone 33 and a combustion terminating zone 35. Zone 31 is established by connected upper-level, intermediate-level and lower- level fuel ducts 37, 39 and 41. rl`he radiant calcining Zone 33 is established by the upper-level ducts 37 and air ducts 43. The cooling zone 25 lies between the air inlet means 13 and ducts 41. At numeral 45 is shown an air outlet duct which receives cooling air which has been warmed by abstraction of heat from the material in the lower part of the cooling zone. This air is abstracted by means of a fan or blower 47. Part of the air abstracted by the fan 47 is delivered over a line 49 to a burner B to be described, and part is delivered over` a line 51 to a gas recirculation line 53. Line 53 connects outlets 29 with a spent gas recirculation fan 55. The remainder of the air from the fan 47 is carried over a line 57 to the inlet ports 43 to supply the terminal combustion air for calcination in the zone 35.

At 59 is shown an exhaust fan, connected over line 61 with the uppermost outlet ports 27. Connected to this line 61 is a leakage air intercept 63 for the charger 3 and a tempering air inlet 65. The main exhaust from the fan 59 is indicated at 67, some of this being abstracted over a line 69 so as to supply some comparatively cool recirculating gases to the line 53. If desired, the intercept 63 may be closed off at valve 64. In thisevent the charger 3 may be pressurized by opening a Valve 65y in pressure line 68 from blower fan 59. In the latter event no tramp air enters line 69 and the gases in 61 are of a composition such as in the kiln.

The line 53 is connected with the ports 29 and withdraws therefrom hot recirculation gases rich in CO2.v An

`air tempering inlet 71 supplies some air to the hot gas recirculation line 53. Recirculation fan 55 blows recirculating gas into the burner B, shown diagrammatically in FIG. l and in detail in FlGS. 2-4. An oil inlet 73 supplies oil to the burner.

The burner B is connected with a flare construction 75, forming part of shaft 1, the flare 75 being connected with the intermediate-level fuel duct 39. This flare has a constricted throat forming an inlet 77 which is in communication with the central outlet 79 of a scroll 81 supported on the construction 75 and on the outside of shaft 1. The inlet 83 of the scroll S1 is controlled by means of pivoted dampers 35 and 87, adapted to be operated from handles S9 and 91, respectively. The handles may be locked in any adjusted positions of the dampers 85 and 87, lock means93 and 95 thereon operating in conjunction with arcuate slots 97 and 99, respectively. The handles 89 and 91 are illustrated in the solid-line closed positions of the dampers S5 and 87 (FIGS. 2 and 4). Dottedline open positions of the dampers are shown in FlG. 4.

Recirculating gases are supplied to the inlet 83 over a pipe 163, the latter being connected with the outlet of the recirculating fan 55.

As shown in FIG. 3, the left-hand wall 101 of the scroll is the one which is attached to the ilare construction at the throat 77, the opening 79 of wall 1111 registering with the throat 77. Its other scroll wall 133 has an opening 135 covered by a door 107, supported on a hinge mechanism 109 for opening and closing movements. The door is adapted to be locked shut by a lever lock 111 and a hinge lock 113. The door 107 carries a sleeve 115 in which is a slidably adjustable air tube 117, adapted to be held in position by a set screw 119. A packinggland 121 prevents air leakage from the inside of the scroll S1 around the tube 117.

At the inner end of the air tube 117 is a aring end bell or collar 123 which in the normally adjusted position of the tube 117 in sleeve 115 will lie in the region of the inlet 77. Tube 117 has a side air inlet 125 in which is a control damper 127. The air entering the inlet 125 and supplying the air tube 117 is the heated air abstracted from the cooler 25 by the blower 47. The path of this air is indicated at 129. It has a spiraling action in the tube 117, as indicated in FlG. 3. At the outer end of the tube 117 is a closure member 131 in which is slidable an oil inlet pipe 133, adapted to be locked in a desired axial position by set screw 135. The closure 131 is packed against leakage of air, as indicated at 137. The closure 131 mounts the oil pipe 133 concentrically in the air tube 117.

At its outlet end the oil pipe 133 is supplied with a spray nozzle 139. At its other end it carries a cap 141, having an inlet boss 143 with which a nipple 145 may be connected. The connection is made by a saddle 147, pivoted at 149 to the nipple 145. This saddle is adapted to pivot so as to straddle the cap 141. It has threaded through its upper part a handle-operablescrew 149, reacting when threaded in against the cap 141 to draw the nipple 145 into connection with the inlet 143.

The inlet fuel line 73 supplies the nipple with fuel under pressure, for ow out of the nozzle 139 as a spray, indicated at 153. Any excess flows to the fuel sump over fuel relief line 155. In order to steady the position of the oil pipe 133, the nipple 145 is provided with a stem 157, slidable for adjustment in guiding support 159 on the tube 117 and adapted to be locked in position by a set screw 161.

Operation of the burner is as follows: Oil admitted under pressure from line 73 into the oil pipe 133 emerges from the nozzle 139 as a conical spray from cooling zone 25 and ignites evenly throughout the finishing zone 31, this zone 31 being above ignition temperature.

The rising hot gases cause a radiant calcining action in the radiant heating zone 33. The addition of recirculating gas not only assures even heat distribution throughout the cross section of the shaft 1, but has a tempering and heat-distributive action adapted to avoid hot spots throughout the calcining zone.

The purpose of the slidable arrangement of the air tube 117 with its contained oil pipe 133 on the door 167 is to permit convenient access to `the spray nozzle when adjustments or repairs are required. It will be apparent that the door may be opened when the air tube 117 is retracted from the inlet 77.

The amount of hot air abstracted at outlets 45 for vaporizaition is of a volume sufficient for gasifying the oil spray at 153. The amount of recirculating gas abstracted v from outlets 29 above thecalcining zone 23 is of greater 153. Air entering tube 117 tangentially from pipe 125 and n line 49 spirals along the path shown at 129 and emerges spirally from the inside of bell 123 and into the conical spray 153. This air, coming from the cooler 25, has picked up heat at a temperature which can be reliably held at the value required for vaporization of the oil, including heavy oil. Substantially complete and reliable oil gasification is thus assured. This distinguishes from the scheme for gasifying the oil used in said Patent 2,532,077, wherein only the recirculating gas of variable temperature is depended upon for gasification. Nevertheless, in the present case the recirculating gas is employed by introducing it into the inlet 77 through the scroll 81. This gives it a spiraling action through the throat 77 and ilare 75.

This spiraling action occurs around the cone of vaporization 153, resulting in effective tempering. The collar 123 also has a tendency to keep a to-be-described rotating stream of air-oil on the one hand, and the recirculating gas on the other hand, separate for a longer period than if this collar were not employed. This improves the injection properties but it is to be understood that ultimately the gasied oil, air, and recirculating gases become mixed. Therefore, the distribution of the gasilied fuel in the finishing zone 31 and above will be even throughout the cross section of the kiln, AAs the mixture of gasilied fuel,

capacity, which accounts for the use of the comparatively large scroll 81 employed for its introduction into the throat 77. The flare 75 and end bell 123 initially maintain a separation of the stream of vaponzing oil and air issuing from the terminus of the tube 117. Beyond the ilare 75 and in the passages 37, 39 and 41, the recirculating gas mixes with the vaporized oil and air that was introduced therewith.

Advantages of the invention will be apparent-from the above description, being:

(l) The use of a limited amount of the heated air from the cooler forreliably maintaining the critical vaporizing and gasifying temperature needed for oil gasifcation in the spray 153, particularly in the case of the use of heavy oil;

(2) The employment in combination of a spiraling introduction of the air around the oil spray head 139;

(3) The introduction in combination of the tempering recirculating gas around the vaporizing spray cone;

(4) The spiraling action of the recirculating gas through the throat 7'7 and ilare 75;

(5) The introduction of the recirculating gas around the spray cone from the tube 117 and over the Aflaring end bell 123; and,

(6) The mounting of the spraying and vaporizing assembly of the air tube and oil pipe on the door'attached to the scroll and extending therethrough, providing a compact but accessible arrangement for the firing means.

In view of the above, it will be seen that the several objects of the invention arey achieved and other advantageous results attained.

As various changes could be made in the above constructions without departing from the scope of the invention, it is intended lthat all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limitv ing sense.

I claim:

l. A calcining kiln comprising a hollow shaft containing a calcining zone and a cooling zone therebelow, said shaft having first a tiring inlet to the calcining zone, second a spent-gas outlet above said calcining zone, third a cooling air inlet adjacent the lower end of the cooling zone, and fourth a hot-air outlet extending from the cooling zone above said cooling air inlet thereto, firing apparatus connected with said 'ring inlet comprising an oil spray nozzle, an air pipe which surrounds and has an open end near said oil spray nozzle, said air pipe having an Vair connection with said hot-air outlet from thecooling Azone, hot-air circulating means in said air connection, whereby a central admixture of oil spray and surrounding hot air enters said tiring inlet to initiate vaporization of the oil, said firing apparatus including a throatforming structure around the air pipe and oil'spray nozzle, a spiral duct around said air pipe terminating in said throat-forming structure, said duct having a spent-gas connection with said spent-gas outlet, spent-gas circula-ting means in said spent-gas connection adapted to force Aspent gas from said spent-gas outlet through said spiral duct and spirdly through said throat-forming structure around the mixture of hot air and vaporizing oil.

2. A calcining kiln according to claim 1, including means adapted to spiral hot air in its passage through and from the air pipe, and a flaring end bell on the open end of the air pipe adjacent the spray nozzle vadapted to deect spent gas in said throat-forming structure radial- 1y around the mixture of vaporizing oil and hot air.

3. A calcining kiln according to claim 2, wherein said throat-forming structure is constituted by a portion converging frorn said spiral duct toward the end of the air pipe, and a aring portion extending outward from the flared end bell.

References Cited in the tile of this patent UNITED STA'VIES PATENTS 1,023,422 Despujols Apr. 16, 1912 1,101,790 Doherty June 20, 1914 2,090,567 Andler Aug. 17, 1937 2,110,209 Engels Mar. 8, 193'8 2,502,210 Demuth Mar. 28, 1950 2,505,337 Murphy Apr. 25, 1950 2,540,416 Asscher Feb. 6, 1951

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