US2152367A

US2152367A - Drying apparatus

Info

Publication number: US2152367A
Application number: US201681A
Authority: US
Inventors: Alfred R Smith
Original assignee: Combustion Engineering Inc
Current assignee: Combustion Engineering Inc
Priority date: 1938-04-13
Filing date: 1938-04-13
Publication date: 1939-03-28
Anticipated expiration: 1956-03-28
Also published as: DE710610C

Description

March 28, 1939. r U A. R. SMITH 2,152,367

' 'DRYING APP-ARATUS Filed April 15, 1938 s Sheets-Sheet 1 INVENTORV fllrm f1. Smzli Q ZL'M.

ATTORNEY March 28, 1 939. AQR. SMITH v 2,152,367

DRYING APPARATUS Filed April 13, 1958 5 Sheets-Sheet 2 INVENTOR XFAZLLL ATTORNEY March 28, 1939. R s H 2,152,367

DRYING APPARATUS Filed April 13, 1938 5 sheets-Sheet 3 INVENTOR ATTORNEY Patented Mar. 28, 1939 DRYING APPARATUS Alfred R. Smith, Forest'Hills, N. Y., assignor'to Combustion Engineering Company, Inc., New

York, N. Y.

Application April 13, 1938, Serial No. 201,681

Claims.

' This invention relates to systems i'or drying wet materials and has for its purpose the provision of certain improved features in one typeof apparatus used for this purpose. 5 A statement of what the improved features are will be postponed until a description of the ap paratus generally has been given.

In the following specification reference will be made to the accompanying drawings, the three figures of which showschematically three instal lations embodying the invention, Fig. 1 showing it a in one form, and Figs. 2 and 3 showing it each in a varied form;

Referring first to Fig. 1, the material to be 1| dried is fed into a drying tower I through a pipe 2. Hot gases from the furnace. 3 are led to the drying tower I through a'pipe connection 5. The

- material to be treated passes downward" through the tower I togetherwith the drying gases and reaches the disintegrating mill 1 where the material is agitated and comminuted and where the principal part of the drying operation occurs.

' .The mill is driven by any desired means such as the motor 9. The conmiinuted material together with the drying gases and the moisture evaporated from the material leave the mill 1 and are conducted by conduit I I to the cyclone separator I3. Here the solids are separated out, collecting at the lowerend of the'cyclone, the gases, substantially cleared of solids, being carried off through the connection I5, to a fan II, which forces them through duct l9 to a point of disposal.

The solids separated out are taken off through the outlet 2|. ,Raw material for treatment is brought in through the connection 23 from the hopper 24. -The installation illustrated is adapted particularly to drying very wet materials. Such materials present some difliculties in handling, which 40 difliculties are, in accordance with prior practice, overcome by admixing a certain amountof previously dried material'with the incoming raw material. In accordance withthis prior practice, theconnection'25 from outlet 2I carries to the (5 mixer 21 the required portion of the dried material, the portion, not required being discharged through branch 29. Damper3l makes it'possible to dividethe dried material in the desired ratio.-

The-dried material is thoroughly mingled with the raw wet material in the mixer-conveyor 21 and the mixture is discharged by the conveyor 7 into pipe 2.

During the evaporation of the moisture, the temperature of the gases brought in through pipe 56 5 falls and additional hot gases are continuously supplied through the pipe 5. This means that a corresponding amount of gases must be discharged at some point from the system. In addition, the moisture evaporated increases the amount of gases and this excess must also be dis-"- charged. I

The gases to be vented may in some cases be discharged directly to the atmosphere. At 38 is shown a vent to atmosphere for this purpose, the

vent being equipped with damper :4. at the 1b point where the material is fe'd into the delivery pipe 2, there has heretofore inevitably been some .leakage of gases. Either air leaks in, in indefinite,

uncontrolled amounts, or gases leak outward from the system making it uncomfortable or 11130551.- 15 ble to work in the vicinity of the feeding device. Ohe ofthe main objects of my invention is to obviate this difliculty and this is accomplished by providing means to keep the pressure in the feeding device adjacent'to-the inlet to pipe 2 at 20 or substantially at atmosphere. For this purpose I- provide a branch connection 31 from pipe I 9 to the interior of the casing of mixer 21.

damper I is also provided in pipe 2. b By this provision a number ofadvantageousfeatures are obtained, including the removal of the diihculty mentioned. Primarily, outward leakage can be prevented entirely and at the same time the amount of airleakage into the system at 30 this point can be minimized. In addition, dust carried by gases leaving the separator through pipe I 5 is by the improvement partly saved instead of being lost by discharge into the air or to the furmice. To discharge such dust to the air is usually 5 objectionable and to discharge it to the air or'deliver it to the furnace is wasteful where the dust is of any value. To the extent that it is saved and reclaimed, the invention has a beneficial eiIect, in addition to the main one first mentioned. The 40 arrangement also has the great advantage that it makes it possible, as explained more fully below, to regulate the amount of hot gases taken from the furnace without having a. damper in pipe 3 "through pipe I] and disintegrator l to drying tower l and pipe 2. On its outlet side, the fancreates a pressure above atmosphere in pipes I9 and 31. Obviously. y a proper setting oioamp- 5s,

This branch is equipped with a damper 39 and a ers 39 and 4|, primarily the former, a pressure equal to atmospheric or slightly above or slightly below, can be obtained in the mixer casing.-

Preferably the pressure is made slightly sub-atmospheric, so that there. is no escape at this point of gases and dust, but only a slight inward leakage of air. v

To regulate the amount of hot 'gases taken from furnace 3 through pipe 5, damper 4| is suitably adjusted. Thus, if the gases coming from the cyclone are too hot, so that their discharge would entail waste of useful heat, and it is therefore desired to cut down the hot gas supply coming from the furnace, damper 4| is moved toward its open position. This will tend to suck in air through the openings from the atmosphere into the casing 21, and to complete the setting,

damper 39 is also moved far enough toward its.

wide-open position to maintain or to re-establish the slightly sub-atmospheric pressure in the casing 21. Gases will then be drawn away-faster from l9 and 31, and as a result less gases will be drawn in through 5.' Conversely, if the gases from the separator are too cool, dampers 4| and 39 are moved in a direction toward their closed position, thereby causing less gas to be withdrawn from H! and 31 and more to be taken in through 5.

Preferably this adjustment is made automatically, and for this purpose the-following apparatus is provided. At l9 there is arranged the bulb element 43 of aithermostatic control connected by 45 to the element 41 actuating damper 4|. Any suitable thermostatic control may be employed, which will open and close damper 4| by the right amount responsively to temperature variations. in the gases.

To keep the pressure in 21 at the desired point, pressure responsive means 5|, subject'to the pressure in 21, are employed, acting through connection 49 and actuating means 53 to set the damper 39 to maintain the desired pressure in 21.

The usual means, such as thermostat 55, controlling the fuel and air supplied to the furnace, are used to hold the temperature-oi the gases passing through pipe 5 constant.

, In Fig. 2 isshown a variation of the form of the invention from that described above. This variation consists in the addition of pipe 6|, branching off from 31 and extending to pipe 5. In this pipe is a damper 63 actuated by thermoe static means 65 responsively to temperatures at the fan outlet. This damper acts like damper 4| described above to regulate the amount of gases taken oh the furnace through pipe 5. In the form of Fig, 1 all the gases, which are to be recirculated, are passed through the conveyorrnixer housing. The form of Fig. 2 is used in cases where the amount of the recirculated gases is too large for this, or where for some-other reason it is undesirable to send all these gases through the casing. The dampers 39 and 4| in pipes 31 and 2 are used as heretofore, but the by-pass 6| takes care of the greater part of the recirculated gases.

In some instances it will be necessary or desir-- able to deodorize all gases before discharging them to the atmosphere.

An arrangement for I this purpose embodying-my invention is shown I in Fig. 3. The arrangement is quite similar to that of Fig. 1, but instead of discharging excess gases to atmosphere by means of vent 33, a con nection 33a to the furnace is provided which discharges the gases to some point in the furnace where the temperature is high enough to deodorize these gases. In the form shown, the gases pass downward through the baflie 61 and are discharged into the furnace at the lower end of the baiiie. The excess is all ultimately discharged from the stack 69. The amount of gases taken off the furnacethrough 5, and the regulation of the pressure in casing '21 are effected exactly as in the form of Fig. 1.

What I claim is: 1. In apparatus of the kind described, the com- .bination of a drying and pulverizing mill, a

furnace, a duct from the furnace to the mill to supply drying gases, a mixing device means to deliver to 'the mixing device raw wet material to be treated, meansto deliver to the mixing device treated dried material to be mixed in the mixing device with the raw material, a separator, a fan, a duct carrying the mixed material from the mixing device to the mill, a duct to convey the gases and material from the mill to the separator, means to conduct the gases from the separator to the inlet of the fan, a duct from the outlet of the fan to the mixing device, damper means in the duct to the mixing device, and damper means in the duct fromthe mixing device, where'- by the pressure in the mixing device can be adjusted to a point differing slightly from atmosphere.

2. Apparatus in accordance with claim 1, and. further comprising means automatically adjusting the position of the damper in the duct leading to the mixer responsively to pressure changes in the mixer, to keep such pressure slightly below atmospheric. 3. Apparatus in accordance with claim 1, and further comprising means automatically adjustthe position of the damper in the ,duct leading from the mixer to temperature changesin the gases coming from thefan.

5. Apparatus in accordance with claim 1, and further comprising means responsive to pressure conditions in the mixing device to open further the damper in the duct leading to the mixing device when the pressure in the mixing device falls below a predetermined point, and to move'it in a closing direction when such pressure falls below a predetermined point, and means respon-- sive to temperature conditions of the gases lea-v ing the fan to move the damper in the duct leaving the mixing device in .an opening direction when said temperature falls below a predetermined point, and to move it in a closing dlrec-' a predetermined point.

tion when it rises above ALFRED B. SMITH,

, ing the position of the damper in the duct lead-