Patent Publication Number: US-3875904-A

Title: Device for cleaning air passage openings in the walls of a refuse burning furnace

Description:
United States Patent Astrt&#39;im 14 1 Apr. 8, 1975 i 1 DEVICE FOR CLEANING AIR PASSAGE [56} References Cited OPENINGS IN THE WALLS OF A REFUSE UNlTED STATES PATENTS BURNING FURNACE 2.480394 8/!949 Cavers et al. 200/42 x 5 1 Q t 3.043.250 7/1962 Nyberg 0. 122/235 x [7 1 Memo Astmm S emngwnd 3.361.419 1/1966 Siemsscn 200/42 x 3.742.916 7/l973 Wessberg et al l Ill/I815 [73] Assignee: Gotaverken Angteknik AB.  
  Goteborg Sweden Primary Examiner-Kenneth W. Sprague I22 Filed. Feb 20 1974 Almrnev, Agent, or Firm-Holman &amp; Stern [21] App]. No.: 444.152 [57] ABSTRACT An air passage in the wall of a refuse burning furnace 30 Foreign Appncafio. p Data is cleaned by means of a sleeve. which normally is Mar 5 &#39;97.; Sweden 019mg used for governing the air flow by axial displacement of one of its ends within the passage proper. This 52 I IIIIIIIII u 2.5 sleeve is mounted so it can be occasionally pushed I U S u 22/235 42,? right through the passage and furthermore in such a l in CI F22b37/48 manner that air is prevented. in use. from passing into 5 a 266/41 the sleeve. whereby the latter may be used for inspection purposes.  
 3 Claims, 4 Drawing Figures PATENTEUAPR 8IHT5 SHEET 1 OF 3 FIG.]  
 PATENTEDAFR&#39; 81% sum 2 or 3 FIG.2  
  DEVICE FOR CLEANING AIR PASSAGE OPENINGS IN THE WALLS OF A REFUSE BURNING FURNACE BACKGROUND OF THE INVENTION With many kinds of refuse burning furnaces the combustion air is supplied through a number of passages in the walls of the furnace, with said passages being connected to a common air supply conduit in groups. so called registers. Especially with furnaces adapted for the combustion of waste liquor from cellulose pulp manufacture, the air passages will be rapidly clogged partly by matter contained in the combustion gases and partly by slag products running down the furnace walls.  
  Different ways of cleaning these passages have been proposed during the years. including mechanical scraping devices as well as arrangements for directing the flow of combustion air in such a manner that a blasting of the faces most likely to be clogged is obtained.  
  One embodiment of last mentioned type includes a sleeve which is displaceable towards and away from the passage and which directs a stream of air branched off from the volume of air alloted to the pertaining passage. so it is forced to flow along the walls of the passage. A device of this type will show fine cleaning results, but it suffers from two disadvantages.  
  On the one hand, it is necessary to vary the main body of air depending upon the occasional combustion intensity, and as the cleaning occurs through a (small) branched stream of the total volume, it will either be necessary to adjust two streams. or to accept the fact that the blasting will not be uniform during all operating conditions.  
  On the other hand, it is necessary, occasionally to lance the fuel bed within the furnace through an air passage. The air supply conduit must then, with this type of cleaning device as well as with other known devices, be opened to permit the introduction ofa lancing tool. The operator will then have to face a jet of hot air. possibly mixed with gas. blowing out through the opening in the air conduit.  
 SUMMARY OF THE INVENTION A more uniform cleaning and a full avoidance of these backwardly directed air streams is, according to the invention, attained if the sleeve is sealingly fitted into the air conduit, and is displaceable with respect to a guiding means within the same. The end of the sleeve remote from the furnace. being is accessible from outside the conduit. and the arrangement further is such that air is prevented from entering the sleeve.  
  The full volume of air to be supplied through the pertaining passage will then pass out through the annular passage between the sleeve and the wall of the passage. Even the smallest possible volume of air will then be larger than the cleaning stream branched off with the older type ofdevice. As the air flows outside the sleeve an ejector action is effected which will cause a subpressure within the sleeve. When the lancing opening is used. an inflow of air from the boiler house into the sleeve is obtained instead of the previous back blow of hot air. The lancing operation will. therefore, be much easier.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of a portion of the wall of furnace for the combustion of waste liquor,  
  FIG. 2 shows a longitudinal section through an air passage with governing means.  
  FIG. 3 shows a section corresponding to FIG. 2, through a modified embodiment. and  
  FIG. 4 shows a further arrangement using this embodiment.  
 DESCRIPTION OF SOME PREFERRED EMBODIMENTS The wall of the furnace is supported by a number of water cooled tubes 10, which are welded together by means of fins 11 in such a manner that a gas tight structure is obtained. This is, towards the furnace, covered by a protecting cladding of known type, not shown here.  
  A number of air passages. 12 have been provided at suitable positions in the wall, with each passage being formed by bending two tubes away from each other.  
  These passages are, depending upon the type and the size of the furnace, combined into registers for the supply of primary and secondary air, respectively. The passages are, in connected to conduits I3 supplying preheated air.  
  In order to make possible an individual adjustment of the air flowing out through a passage. a sleeve 14 is provided therein and arranged in such a manner that it can be axially displaced towards and away from the furnace wall. A wall 15 defining the air passage is formed in such a manner that the cross section of the passage will decrease in the direction of flow. but may form a parallel terminal portion at the mouth of the passage.  
  The position of sleeve 14 within the passage will thus determine the size of the annular passage through which the air may flow out into the furnace. This outflow will thus occur adjacent to the wall of the passage only. and a strong blasting of the wall face will thus be brought about, so dry matter as well as droplets of slag will be blown away.  
  The sleeve 14 is telescopically displaceable in a guide means 16 which is fitted into the air supply conduit 13, here a branch part connected thereto. Between the guide means 16 and the sleeve 14, a resilient collar 17 is provided. which prevents air from the conduit entering the sleeve.  
  The guide means 16 extends outside the wall of the supply conduit, so its end wall 18 will be accessible outside the conduit. but otherwise is hermetically fitted therein.  
  In the end wall of the guide means. an elongated. screw threaded member 19 is fitted. and by means of which the sleeve 14 may be operated. The end wall fur ther carries a window 20, which is directed in such a manner that it is possible to look into the furnace through the guide means and the sleeve. so a portion of the fuel bed may be watched.  
  The end wall 18 further contains a lancing opening 21, which makes possible the introduction of a rod like too] into the furnace in order to work the fuel bed or to break away difficult accumulations of slag, which accidentally may have collected in the air passage, in spite of the forceful air blasting above described.  
  As all air is flowing out around the mouth of the sleeve, a subpressure will be caused therein as well as in the guide means. When the lancing opening is used no disagreable blackblowing&#34; of hot air will occur. which hitherto has been a source of trouble and also has caused injuries of the staff and damaged equipmentv The lancing opening is normally closed by a tophinged lid 22 and it is sufficiently heavy to remain closed in spite of the sub-pressure. The lid will automatically be swung aside when the tool is introduced.  
  The sleeve 14 and the screw 19, respectively. have such a length that the end of the sleeve. turned towards the furnace. may be brought right through the passage. The sleeve may. in this manner. be used to scrape away collections of matter at the mouth of the passage.  
  FIG. 3 shows a first modification of the device. The sleeve 14 is. here by means of a bellows 30, connected to the back wall of the air conduit 13:: and is carried by a support 31, which runs in a guide means 32. This is. in turn. carried by a bracket 33 within the air conduit 13. The screw 19 is connected with the support 31 and can. in the same manner as described in connection with the previous embodiment. displace the sleeve to wards and away from the opening 15. The bellows makes these movements possible without any air leaking into the sleeve from the surrounding air conduit.  
  Outside the air conduit proper 13a. there is a further conduit 34. which is connected to at least some of the sleeves [4. Within a cellulose pulp mill. there are a number of devices. for instance mixer tanks. from which mist or vapor containing chemicals will issue. and which it may be difficult to ventilate away.  
  The conduit 34 is connected to one or more ofthese devices located not too far away from the furnace. The sub-pressure in the sleeve 14 is sufficient to draw these vapors into the furnace where they will be destroyed and some chemicals possibly reclaimed.  
  The inspection windovi 20 and the lancing opening 2] are here mounted in a hinged lid 35. whereby full access is made possible. should such be required. In stead offitting the additional conduit 34 outside the air conduit 13a. it may be located inside the same and be connected to sleeve 14 downstream ofthe bellows. The additional conduit 34 will then also have to include a resilient portion so it can follow the movements of the sleeve.  
  FIG. 4 shows a special use. or a further development. of the arrangement according to FIG. 3. The sleeve 14 is here dimensioned in a manner to permit the introduction ofa camera 36 of TV-type. about to its mouth. The camera is maintained in a desired position by means of a chain 40. and transfer of the pictures is made by way of cables 37. connected to a monitoring device of known type (not shown).  
  The air flowing around the sleeve 14 will maintain the temperature adjacent to the camera at a constant. known value. A cooling of the camera itself is obtained by means of air supplied through a hose 38 enclosing the cables 37. On this occasion. a specially formed lid 39 is used to close the extending end of the sleeve.  
 By mounting a number of cameras in suitably posi tioned air passages. it will be possible to follow the combustion on the fuel bed from a centrally located operating post. which has hitherto been impossible.  
 in this manner. it is simple to follow the influence of different kinds of liquor spraying nozzles and of air inlet arrangements. as well of different pressures and inlet velocities of the liquor and the air. respectively. With a continuous survey. it is possible to control the combustion, and to make rapid adjustments if tendencies to incomplete combustion should occur for instance due to an unstable flame or a leaking tube. A fully developed monitoring system may include a programmed governing unit determining the supply of liquor and air. as well as possible additional fuel. in an optimal manner depending upon variations of selected parameters.  
  Besides with waste liquor combustion furnaces, the invention may be used with other types of furnaces for the combustion of refuse causing a high degree of ash products having a tendency of clog the air passages. The size and the shape of the latter as well as the grouping thereof to the air conduits will have to be suited to size and the capacity of the furnace. As the sleeve and its guide are fully defined with respect to the air conduit. it is not necessary to lower the air pressure during a lancing operation and such activity at one passage will thus not detrimentally influence the flow of air to adjacent passages.  
 What I claim is:  
  1. In a refuse burning furnace. walls defining the furnace. a number of combustion air passage openings in the walls. conduit means outside said walls for supplying air to said passages openings and means. at least at some of said passages openings. for mechanically scraping the passage openings. said means including a sleeve extending into and being axially displaceable with respect to the pertaining passage opening. the improvement of means defining the passage opening so as to present a cross-section decreasing in the direction of flow. means for hermetically mounting the end of the sleeve remote from the wall with respect to the conduit. and further means for making the end of the sleeve remote from the wall accessible from outside the air conduit.  
  2. The refuse burning furnace according to claim 1, in which a conduit connected to a source generating mist. gases or vapor and located adjacent to the furnace is connected to the sleeve.  
  3. The refuse burning furnace according to claim 1, including a camera device for monitoring the combustion and in which the sleeve has such dimensions and the further means for making the end of the sleeve remote from the wall accessible is arranged so as to permit the introduction into the sleeve about to the inner end thereof. of said cameral device.