US3276442A - Furnace observation port - Google Patents

Description

Oct. 4, 1966 K. s. SVENDSEN FURNACE OBSERVATION PORT 2 Sheets-$heet 1 Filed Feb. 24, 1965 FIG. I

INVENTOR. KONRAD S. SVENIDSEN MiG 140v ATTORNEY Oct. 4, 1966 K. s. SVENDSEN FURNACE OBSERVATION PORT 2 Sheets-Sheet 2 Filed Feb. 24, 1965 FIG. 4

FIG. 3

INVENTOR. KONRAD s. SVENDSEN ATTORNEY United States Patent 3,276,442 FURNACE OBSERVATION PORT Konrad S. Svendsen, Bloomfield, Conn., assignor to Combustion Engineering, Inc., Windsor, Conn., a corporation of Delaware Filed Feb. 24, 1965, Ser. No. 434,939 1 Claim. '(Cl. 126--200) This invention relates to passageways or openings in walls of pressurized furnaces or other chambers under superatmospheric pressure, and particularly to means for maintaining such passageways capable of being seen through at all times.

In many pressurized furnaces it is desirable to provide an opening for the purpose of observing the inside of the furnace, and to permit access to the furance for the purpose of cleaning or lancing the furnace walls. A glass window is usually utilized for observation of the furnace interior. When a dirty fuel, for example coal, is being burned in the furnace, difiiculties are encountered in keeping the glass from clouding or fogging over, and preventing abuildup of ash thereon.

It is an object of the present invention to provide an observation port for a pressurized furnace which will allow observation of a large portion of the furnace interior, and to effectively maintain the glass clean and cool at all times, so that visibility will not be restricted.

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds. An illustrative embodiment of the invention is shown in the accompanying drawings wherein:

FIGURE 1 is a front view of a furnace observation port;

FIGURE 2 is a sectional plan view of the port;

FIGURE 3 is a sectional side view of the furnace port taken along lines 3-3 of FIGURE 2; and

FIGURE 4 is a sectional view taken along lines 4-4 of FIGURE 2.

Looking now to FIGURE 1, denotes a furnace observation door for a pressurized furnace, which door contains a rectangular glass plate 12 therein. The door 10 can be pivoted upwardly about hinge pin 14. Nut 20 holds the door securely on hinge 14. On the other side of the door is bolt 22 and its associated threaded hand knob 24, by means of which the door can be tightly secured in place, covering the opening or passageway leading to the furnace interior.

Looking now to FIGURE 2, the entire observation port housing 18 is secured to the furnace wall 16 in any suitable manner, for example by welding. The housing 18 contains the rectangular passageway 19, which communicates at its inner end with the furnace interior. Retaining ring 26 holds the glass plate securely in place in the furnace door. O-ring 28 forms a seal between the glass plate and the door. A sealing gasket 30, contained in the furnace door, forms a seal between the door and the housing when the door is in its closed position. The sealing members should be made of a suitable heat resistant material, for example asbestos.

Air for cleaning and cooling the glass plate is directed into annular chamber 32 by way of pipe 34. High pressure air, to be used for forming an effective screen for passageway 19 when the door is opened, is directed into annular chamber 38 by means of pipe 40. This air is discharged into passageway 19 by way of jets 36.

As best seen in FIGURE 3, a plurality of jets 42 discharge the cleaning and cooling air directly onto the surface of the plate glass. This prevents ash from collecting thereon, and also keeps it cool, so that it will not fog or cloud over.

FIGURE 4 illustrates the location of the aspirating jets 36 and the jets 42 used for cleaning and cooling "ice the window. As shown, theh jets 36 are located on either side of the passageway 19, and the jets 42 are located above and below passageway 19. This construction permits housing 18 to be made quite compact. Obviously, if the length of passageway 19 is increased, the amount of the opposite interior furancewall that can be observed is decreased.

By making the glass plate and passageway 19 rectangular, and keeping the length of passageway .19 as short as possible, an observer looking through the window can see a substantial portion of the furnace interior both above and below the level of the observation port. This is particularly advantageous on coal fired furnaces. By looking through the observation ports, an operator can determine the slag conditions in the furnace and take corrective action when required.

The operation of the device is as follows. During normal operation of the furnace, with door 10 closed, cool air is continuously supplied to jets 42. This air in sweeping across the face of glass 12 maintains it relatively 0001, thereby preventing it from fogging over. The cool air also prevents ash particles from accumulating on the surface of the glass. This is particularly a problem when coal is the fuel being burned in the furnace. The cool air also reduces the problem of heat stresses being created in the glass due to temperature differentials.

When it is desired to gain access to the furnace, hand knob 24 is unthreaded, and also nut 20. The door can then be pivoted upwardly around hinge pin 14. When the door is opened, high pressure air is delivered to annular chamber 38, and is discharged into passageway 19 through jets 36. These jets of high pressure .air are directed at a common line of intersection, which is preferably some distance from the inner edge of passageway 19. This forms an effective screen which prevent hot combustion gasses from escaping through the passageway, which hot gasses could seriously injure an observer if allowed to escape from the furnace. When the door is again closed, the high pressure air can be shut off.

For a passageway approximately 2 wide and 4" high, it has been found that the air for forming the protective screen should be approximately 65 p.s.i. This forms an effective screen against puffs of combustion gases up to a maximum of 40" water, or approximately 1.5 p.s.i. The normal operating pressure of a pressurized furnace is 18" of water above atmospheric pressure, or somewhat less than 1 p.s.i. above atmospheric pressure.

The cleaning and cooling air which is continuously directed at the glass window need not be under nearly as high a pressure as the aspirating or protective screen air. All it need be is 1" to 4" W.G. (water gauge) above the operating pressure of the furnace, so that it can be discharged through the jets 38 with sufficient velocity so as to sweep across the surface of the glass: plate. Since this cleaning and cooling air is introduced into passageway 19 continuously during operation of the furnace, it is economically necessary to keep the pressure of this fluid down to the absolute minimum.

While I have illustrated and described a preferred embodiment of my invention, it will be understood that minor changes in construction and arrangement of parts may be made without departing from the spirit and scope of the invention as claimed. It is therefore intended that all matter contained in the description or shown in the accompanying drawings be interpreted as illustrative and not in a limiting sense.

What I claim is:

In a furnace operating under superatmospheric pressure, a passageway, having an inner end and an outer end, extending through one of the walls of said furnace, a door for closing the outer end of the passageway, a glass window contained in the door, a plurality of first jet means positioned along the sides of the passageway, said first jet means having inlets for receiving high pressure gaseous fluid, and outlets opening into the periphery of said passageway, said first jet means being positioned with their outlets closer to the inner end of the passageway than their inlets, so that they direct streams of gaseous fluid under high pressure into said passageway to form a gaseous screen to prevent fluid flow from said furnace out through said passageway when said door is removed from the outer end of the passageway, a plurality of second jet means positioned above and below the pas- :ageway, said second jet means having inlets for receiving oool, pressurized fluid, and outlets opening into the periphery of said passageway, said second jet means References Cited by the Examiner UNITED STATES PATENTS 1,717,637 6/1929 Vastine 12620O 2,850,005 9/1958 Good et a1. 126-200 2,988,024 6/1961 Harris 110-179 being positioned with their outlets closer to the outer 15 KENNETH W. SPRAGUE, Primary Examiner.

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