Abstract:
A nozzle block for a sootblower of the type for cleaning internal heat transfer surfaces of large scale coal fired combustion systems. For cleaning the internal surfaces, a cleaning medium is often used in the form of steam. Due to the cyclical operations and the process of condensation, condensate slugs of water can form in the sootblower fluid flow components. If these slugs are ejected against clean surfaces, undesirable erosion can occur. Several embodiments of nozzle blocks are described each having one or more ejection ports at their distal ends configured to maximize the ejection of condensates while minimizing their cross-sectional area which would diminish nozzle fluidic efficiency. Additional features enhance the ability of the nozzle block to separate and disperse condensate from the slots.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present patent application claims the benefit of priority to the following applications, and is a continuation of PCT Application No. PCT/US2014/015209 filed Feb. 7, 2014, which claims priority to U.S. Provisional Patent Application No. 61/762,613, filed Feb. 8, 2013. 
     
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
       [0002]    This invention is related to a cleaning device for combustion devices and particularly to one for large scale combustion devices for the reduction of soot and/or slag encrustations forming on internal heat exchange surfaces. 
         [0003]    During the combustion process of fossil fuels such as coal, the internal heat exchange surfaces of boilers and other combustion devices become encrusted with slag and soot. In order to enhance the thermal and combustion efficiency of such devices, it is necessary to reduce the amount of encrustations on the heat exchanger surfaces. Numerous techniques for boiler cleaning are in use today. One approach is the use of so-called sootblowers which project a stream of cleaning medium such as air, steam, or water, or mixtures of these materials against the internal heat exchange surfaces which cause the accumulated encrustations to be removed through mechanical and thermal shock. 
         [0004]    Various types of sootblower systems are used today. One type of sootblower is positioned permanently inside a boiler and is actuated periodically to eject a sootblowing medium. Other types are retractable and include the so-called long retracting sootblowers having a long lance tube which is periodically advanced into and retracted from the heat exchanger. The lance tube features one or more nozzles at its distal end from which the cleaning medium is ejected. The retraction feature of these sootblowers enables the lance tube to be removed from the intense heat within the combustion device between the cleaning cycles which would otherwise damage the lance tube. In most applications of long retracting sootblowers the lance tube is simultaneously rotated as it is axially extended into and out of the boiler so that the stream of sootblowing medium traces a helical or oscillating path during the cleaning cycle. Sootblowers are normally operated intermittently in accordance with a schedule which considers cleaning requirements, sootblower medium consumption, boiler thermal efficiency, and various other factors. 
         [0005]    In cases where steam or a mixture which includes steam is used as the cleaning medium and the sootblower is actuated intermittently, there is a tendency for liquid condensate to collect in the cleaning medium supply circuit and lance tube between actuation cycles. At the beginning of the next actuation cycle when the cleaning medium supply valve is opened, the collected condensate is ejected from the cleaning nozzles in the form of liquid slugs. In some conditions, when such slugs of condensate strike the boiler wall surfaces and heat transfer tubes, erosion occurs due to an excessive level of thermal and mechanical shock. Such degradation of the heat exchange components of a boiler can cause failures and limit the operating life of the boiler which is a significant financial cost for the boiler operator. In view of the foregoing, a need exists for a sootblower system which accommodates condensate slugs without causing boiler component damage. 
         [0006]    In addition to concerns regarding condensed steam forming between actuation cycles, or at the beginning of a cleaning cycle, there are applications in which it is desirable to use saturated or low quality steam as the cleaning medium. In such applications, the presence of condensate is expected as part of the cleaning medium flow supplied to the sootblower lance tube during a cleaning cycle. It is accordingly desirable to provide a sootblower lance assembly which permits the use of such cleaning medium while separating and safely ejecting entrained condensate. 
         [0007]    Various sootblower configurations are known which seek to avoid the disadvantages associated with ejection of condensate when using steam as the cleaning medium. An example of such designs is provided with reference to applicant&#39;s previously issued U.S. Pat. No. 5,063,632. Although such devices generally operate satisfactorily, they have a number of significant disadvantages. For example, in some instances, such devices choke the flow of cleaning medium due to interference between the opposed cleaning medium nozzles. Sootblower nozzles are designed to provide efficient conversion of the static and dynamic pressure of the supplied sootblowing medium into a stream ejected from the cleaning nozzle(s) which has a high cleaning effect or peak impact pressure. Fluid flow interference caused by a disrupted cleaning medium flow at the nozzle entrance may lead to performance degradation. Further disadvantages of known sootblower nozzle blocks for condensate ejection include the requirement of complex internal welded components which can become dislodged or deteriorate during use. 
         [0008]    One known technique for reducing condensate ejected from the cleaning nozzles is to use a port at the distal end of the lance tube provided to allow the ejection of condensate at the terminal end along the longitudinal axis of the sootblower nozzle block. This approach, described in the previously referenced US patent, creates a continuously open flow path initially for condensate ejection but thereafter permits cleaning medium to escape. Since cleaning medium ejected along the lance tube longitudinal axis is, in most applications, not useful for providing a cleaning effect, this discharge flow constitutes an efficiency degradation of the sootblower&#39;s operating performance. An ejection port at the nozzle block distal end produces a spray of condensate into the boiler internal volume. Although, as mentioned previously, ejection of condensate in this direction typically does not lead to undesirable consequences, it is preferable that a port for condensate ejection acts as an “inefficient” nozzle, in terms of generating a coherent high velocity stream of condensate at a given supply pressure. Ideally the condensate spray pattern ejected from a condensate port would be highly dispersed with low impact pressure characteristics. 
         [0009]    In sootblowing applications, it is desirable to preserve the supplied sootblowing medium&#39;s dynamic and static pressure as it is converted to a stream of cleaning medium emitted from the lance tube nozzles which provides a high dynamic cleaning effect. Accordingly, it is desirable to provide a nozzle block which provides the previously noted desirable features while maintaining excellent performance in terms of cleaning effect. 
         [0010]    This invention is related to a sootblower system incorporating a novel lance tube nozzle block having features for reducing the quantity of condensate ejected from cleaning nozzles forming on the inside of the nozzle block, lance tube, poppet valve, and related plumbing passageways or entrained in the cleaning medium supply in a manner which does not lead to boiler tube erosion. The sootblower cleaning nozzles which are aimed at the heat transfer surfaces to be cleaned, spray a steam or a steam/air mixture relatively free of condensate. Accordingly, this invention is capable of substantially minimizing the erosive effect caused by an initial output of a slug of condensate, or condensate present in a steady-state condition against heat transfer surfaces in a boiler. The nozzle block in accordance with this invention provides a condensate separation feature and further a means for ejecting the condensate from the nozzle block in a manner which, for intended applications, does not cause boiler tube erosion. Furthermore, the condensate separating effect provided by the nozzle block in accordance with this invention allows the use of saturated steam or a steam/water mixture for the purposes of cooling the lance tube, while avoiding the degree of heat exchanger erosion which would occur if all the condensed or entrained liquid water were sprayed against the heat exchanger surfaces from cleaning nozzles. 
         [0011]    The nozzle block in accordance with an embodiment of this invention is preferably formed as an integral casting and forms two separated flow paths for the cleaning medium. The flow is separated at about the diametric mid-plane of the lance tube inside diameter by a divider wall to define two separated flow paths dedicated to separate nozzles. Each of the flow paths travels to the terminal end of a nozzle block where it undergoes a sharp “U-turn” bend (i.e. about 180°) and then extends rearward and terminates at a sootblower nozzle for spraying the cleaning medium radially from the nozzle block. The two separated flow paths are intertwined within the nozzle block interior. In one embodiment, the terminal end of the nozzle block features a pair of elongated slot passageways which serve to provide an ejection port for condensate. A slot is provided for each of the flow paths and has a particular orientation with respect to the cleaning medium flow to enhance the condensate separation effect. While the slot provides an effective condensate separation effect, it&#39;s cross-sectional flow area remains small, resulting in a low percentage of cleaning medium passing through the slots not available for cleaning purposes. 
         [0012]    Various embodiments of this invention are described. In one embodiment, the previously mentioned flow path orientations are provided with the condensate ejection slots. In a further embodiment, the interior nozzle flow paths have the features for guiding condensate adhering to the internal surfaces of the nozzle block passageways toward and out of the condensate ejection slots. A still further embodiment provides condensate ejection for a single distal end nozzle for a nozzle block which does not divide the flow paths between a pair of nozzles, or with features only a single distal end nozzle. 
         [0013]    Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiment and the appended claims, taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is pictorial view of a long retracting sootblower which is an example of one type of sootblower with which the present invention may be employed; 
           [0015]      FIG. 2  is a pictorial view of a conventional long retracting sootblower showing condensate being ejected against a pendant section of boiler tubes in a boiler; 
           [0016]      FIG. 3  is a pictorial view of a nozzle block in accordance with the present invention; 
           [0017]      FIG. 4  is an end view of the nozzle block shown in  FIG. 3 ; 
           [0018]      FIG. 5  is a side view of the nozzle block shown in  FIG. 3  shown ejecting steam and condensate; 
           [0019]      FIG. 6  is a pictorial view of the nozzle block in accordance with this invention showing internal surfaces in phantom lines; 
           [0020]      FIGS. 7A ,  7 B, and  7 C are alternate pictorial views of the nozzle block inside cavities forming the nozzle passageways shown as cores used to form the inside cavities; 
           [0021]      FIG. 8  is a side view of a nozzle block showing additional features of the invention; 
           [0022]      FIG. 9  is a cross-sectional view through the nozzle block; 
           [0023]      FIG. 10  is a partial cross-sectional view taken along line  10 - 10  from  FIG. 9 ; 
           [0024]      FIG. 11A  is a cross-sectional view taken along line  11 A- 11 A from  FIG. 10 ; 
           [0025]      FIG. 11B  is a cross-sectional view taken along line  11 B- 11 B from  FIG. 13 ; 
           [0026]      FIG. 12  is a cross-sectional view through a nozzle block in accordance with this invention; 
           [0027]      FIG. 13  is another cross-sectional view through a nozzle block in accordance with this invention; 
           [0028]      FIG. 14A  is a pictorial view showing partially in longitudinal section of the nozzle block in accordance with a second embodiment of this invention having a condensate ejection port; and 
           [0029]      FIG. 14B  is a cross-sectional view of the nozzle block shown in  FIG. 14A . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0030]      FIG. 1  illustrates a long retracting type sootblower which is an example of one type which can be employed with the nozzle block in accordance with present invention. The sootblower as shown in  FIG. 1  is generally designated by reference number  10  and has a construction as disclosed by U.S. Pat. No. 3,439,376 granted to J. E. Nelson et al on Apr. 22, 1969, which is hereby incorporated by reference. Sootblower  10  principally comprises frame assembly  12 , lance tube  14 , feed tube  16 , and carriage  18 . Sootblower  10  is attached to an associated boiler by mounting front bracket  19  to boiler side wall  28  (shown in  FIG. 2 ).  FIG. 1  shows sootblower  10  in its normal resting position. Upon actuation, lance tube  14  is extended into and retracted from the boiler interior and is typically simultaneously rotated (either through full rotations as in a helix or in an oscillating motion). A sootblowing cleaning medium such as air, steam, or water, or a mixture of these fluids (or some other material) is supplied to poppet valve  20  and fed through feed tube  16  which is held stationary. As lance tube  14  is extended into the boiler, it telescopes over feed tube  16 . A fluid seal (not shown) is provided between tubes  14  and  16  to enable the sootblowing medium to be ejected from one or more cleaning nozzles  22 . This invention is associated with the use of steam or a steam/air mixture as the cleaning medium, or another cleaning medium in which condensate or entrained liquids may be present. 
         [0031]    Now with reference to  FIG. 2 , a sootblowing system of a conventional configuration is shown as background for presenting the advantages provided by the present invention. As shown in  FIG. 2 , lance tube  14  is shown protruding through the side wall  28  of the heat exchanger which is covered by an array of heat transfer wall tubes  30 . In this application, sootblower  10  is provided for cleaning a pendant (i.e. hanging) section of boiler tubes  32 . Another row of pendant tubes  32  would typically be provided laterally opposite the section shown but is not shown for the sake of clear illustration. Depending on the application, sootblower nozzle  22  may also be oriented to clean other surfaces within a heat exchanger, such as back against wall tubes  30 . As discussed previously, in applications where steam or a steam/air mixture is used as a cleaning medium, between actuation cycles, steam which remains within lance tube  14 , feed tube  16 , and/or the associated fluid supply circuit will condense. In such instances, at the starting point of a cleaning cycle, the condensed liquid may be ejected forcibly from sootblower cleaning nozzles  22 . Also, when using saturated or low quality steam as the cleaning medium, condensate may be present which is entrained in the supplied medium during steady-state operation. As illustrated in  FIG. 2 , such unpurged condensate formed in the cleaning medium feed system or within the sootblower itself or entrained in the supplied cleaning medium is ejected at high velocity through the nozzle  22  onto pendant section boiler tubes  32  and is shown in the form of droplets or slugs  34 . As mentioned previously, this can cause significant deterioration of the heat transfer surfaces within the boiler and this invention seeks to avoid such negative consequences. 
         [0032]    A nozzle block  24  in accordance with a first embodiment of the present invention is illustrated in  FIGS. 3 through 6  and is formed from a body or housing  36 . Preferably, body  36  is formed by a casting process as will be described in further detail in the following description. Nozzle block  24  forms proximal end  38  which is affixed to a hollow lance tube  14  such as by welding. Distal end  40  is the terminal end of the lance tube assembly. Body  36  forms two internal cleaning medium passageways formed by internal wall surfaces referred to as first nozzle passageway  42  and second nozzle passageway  44 . These passageways are separated by divider wall  46  extending along a diametric center plane  68  of nozzle block body  36 . After cleaning medium flows into lance tube  14  and reaches divider wall  46 , two separated flow streams of cleaning medium are created. For both passageways  42  and  44 , the cross-sectional flow area of the flow passageway decreases from the entrance at divider wall  46  and becomes necked down to form axial flow passageways  48  and  50 , respectively, extending on opposite sides of the diametric center plane  68 . These passageways  42  and  44  are generally semi-circular (in cross section) cavities which extend from divider wall  46  toward distal end  40 . Both nozzle passageway  42  and  44  undertake a U-shaped turns (about 180°)  49  and  51  at distal end  40  crossing midplane  68  and transition to retrograde sections  52  and  54 , respectively. These sections  52  and  54  then transition to 90° (approximate) elbow sections  56  and  58  and finally terminate at respective nozzle outlets  60  and  62 , which are centered on midplane  68 . 
         [0033]      FIGS. 7A through 7C  show the configuration of nozzle passageway  42  and  44  by illustrating three-dimensional molding cores  102  and  104  which could be used for casting nozzle block body  36  and forming the internal wall surfaces of the nozzle block. Portions of the cores which form particular features are identified by the reference numbers used for those features with a “c” (for core) suffix (for example, core section  48   c  forms axial flow passageway  48 , etc.). As shown in  FIG. 7A , passageway core sections  42   c  and  44   c  become intertwined with one another and second nozzle passageway core section  44   c  terminates at nozzle outlet core section  62   c , which is farther from distal end  40  than is nozzle outlet core section  60   c . The cross-sectional configuration of the passageway at nozzle outlets  60  and  62  can feature various configurations well known in compressible flow nozzle theory, such as the Laval-type nozzle featuring a converging/diverging wall having a restricted throat cross-sectional area and an enlarging cross-sectional area going from the throat to the discharge nozzle outlet core sections  60   c  and  62   c.    
         [0034]    The configuration of the internal flow passageway within nozzle block  24  are further described in relation to diametric midplane  68  which passes through the nozzle block (see  FIG. 6 ). Divider wall  46  lies on midplane  68 . The first and second axial flow passageway  48  and  50  lie on opposite sides of midplane  68 , and retrograde sections  52  and  54  lie on opposite sides of the midplane from their respective connected nozzle passageway  48  and  50 . Thus, first axial passageway  48  extends along one side of midplane  68 , then U-turn  49  crosses the midplane, and thereafter retrograde section  52  extends on the opposite side of the midplane. Elbow section  56  forms nozzle outlet  60  which lies on midplane  68 . Axial flow passageway  50  has a similar relation to midplane  68 , with nozzle outlet  62  also centered on midplane  68 . 
         [0035]    A significant features of nozzle block  24  is the provision of a pair of condensate ejection slots  64  and  66  extending along mid-lines  65  and  67  respectively, which open at nozzle block body distal end  40 . As shown best by  FIG. 4 , slots  64  and  66  are significantly narrower than their length (“L”) and are oriented such that their narrow (width “W”) dimension is parallel to the flow of cleaning medium as it undergoes U-turns  49  and  51  (the length L dimension is perpendicular to the flow at the slots). The advantages and features of slots  64  and  66  will be described in greater detail. Slots  64  and  66  form extending midlines  65  and  67 , extending in their length (“L”) direction. As mentioned previously, slots  64  and  66  have a constant width (W) along midlines  65  and  67 . The embodiments shown feature slots  64  and  66  formed by midlines  65  and  67  which are straight lines. However, midlines  65  and  67  could be curved, for example in a letter “C” shape, or partially arcuate. Importantly, slot  64  and  66  are oriented such that mid-lines  65  and  67  are at or nearly perpendicular to the flow of fluid passing through nozzle passageway  42  and  44  at U-turns  49  and  51 . Other possible shapes such as slots having a constant width formed along curved paths or other shapes could be provided. In any event, it is a principal feature of the invention that the ejection slots  64  and  66  are not round and have a greater length (L) than width (W) and are oriented such that the width (W) dimension is aligned with the flow path of a cleaning medium as it flows through elbow sections  56  and  58   
         [0036]    The configurations of nozzle internal flow passageways  42  and  46  provide a number of significant features from a fluid flow perspective. By separating the flow into two paths and isolating them, the effects of interference and turbulence caused by their interaction is eliminated. The retrograde folded-back configuration of the passageways provides a long flow path for the fluid flow to become more laminar, thus reducing high degrees of turbulence which degrades nozzle efficiency. By forming nozzle block body  36  as a one-piece casting, problems associated with loose internal components are avoided entirely. The flow of the cleaning medium close to the entire outside surface of nozzle block body  36  from proximal end  38  to distal end  40  ensures that the nozzle block body is cooled by the flow cleaning medium. This avoids formation of highly heated areas of nozzle block  24  which can lead to deterioration. 
         [0037]    The shape and orientation of slots  64  and  66  is important for their operation. Slots  64  and  66  provide an ejection pathway for condensate which is entrained in the cleaning medium flow or forms on internal wall surfaces of the nozzle block body  36 . Slots  64  and  66  are positioned at the outer portion of the internal wall surface of U-turns  49  and  51  (i.e. the outside part of the turns) where inertia of the more dense entrained particulates tend to cause them to flow toward the outer section of the passageway at the U-turns (or the action of the apparent centrifugal force) where it can be intercepted by the presence of slots  64  and  66 . Thus entrained liquid in the cleaning medium flow becomes directed against the outer surface forming U-turns  49  and  51  where the condensate encounters slots  64  and  66 . The internal pressure of the cleaning medium within nozzle block body  36  causes the condensate flowing to slots  64  and  66  to be ejected from the slots. The leakage of cleaning medium through slots  64  and  66  represents an incremental decrease in the efficiency of the cleaning effect provided by the nozzle block  24 . This is the case since cleaning medium escaping slots  64  and  66  is not directed in a manner to provide desired cleaning of heat transfer surfaces. In order to reduce this loss, the cross-sectional flow areas of slots  64  and  66  are intentionally minimized. In one embodiment of the present invention the cross-sectional flow area provided by slots  64  and  66  are about 15% of the cross-sectional area of the throats of their respective nozzle outlets  60  and  62 . 
         [0038]    Slots  64  and  66  can be made very thin in width (W) such that they produce a relatively small flow area. For the embodiments shown, slots  64  and  66  have a length dimension L and a width dimension W, wherein the length (L) is more than five times the width (W) providing a generally rectangular shape. The length (L) of slots  64  and  66  however is selected to ensure that they extend across the majority of the cross-sectional width of the flow passageway at U-turns  49  and  51 , increasing the condensate that is intercepted by the presence of the slots. Prior art systems utilizing round holes at the distal end of the sootblower, while permitting condensate ejection, have an inherent low efficiency caused by the large flow area of the condensate ejection port. Other possible shapes such as slots  64  and  66  having a constant width formed along curved paths or other shapes could be provided. In any event, it is a principal feature of the invention that the ejection slots  64  and  66  are not round and have a greater length (L) than width (W) and are oriented such that the width dimension is aligned with the flow path of a cleaning medium as it flows through U-turn sections  49  and  51 . 
         [0039]      FIG. 5  illustrates operation of nozzle block  24 . As illustrated, steam is ejected from nozzle outlets  60  and  62 . Higher density condensate is shown being ejected from slots  64  and  66  in this figure (shown overlapping). It should be noted that the nozzle blocks in accordance with this invention may not entirely eliminate condensate ejected from sootblower nozzle block cleaning nozzles. However, the substantial reduction in such undesirable condensate ejection is provided which may have a significant positive effect on boiler operation. 
         [0040]    Nozzle block  24  in accordance with this invention has features which provide an additional mechanism for condensate separation and ejection beyond those previously described. In the prior description, the principle of using a centrifugal force effect with higher density condensate is described. This is useful for handling condensate entrained within the cleaning medium flow or adhering to certain surfaces of the flow passageway. It is further the case that condensate tends to collect and flow along the inside wall surfaces of the flow passageways due to the lower fluid velocity encountered at the wall surfaces, a quenching effect provided by cooling of the cleaning medium at the wall surfaces, and a surface tension effect caused by the liquid contacting the wall surfaces. These factors can lead to a layer of condensate flowing along the internal nozzle wall surfaces. Nozzle block  24  incorporates features designed to intercept condensate flowing along the nozzle passageway flow surfaces to direct it toward and out of slots  64  and  66 . 
         [0041]      FIGS. 9 and 10  in particular illustrate the provision of water corral  80 , which is a raised V-shaped (as seen in  FIG. 10 ) wall  82  formed on the inside wall surface of axial flow passageways  48  and  50  just before U-turns  49  and  51  (inside refers to the surface near the inner radii of the turns). Condensate adhering on the inside wall surface  76  (best shown in  FIG. 10 ) encounters wall  82  and is diverted to flow toward another wall feature termed a wall scraper  84  in the form of a ledge or fin which directs the condensate toward the outside surface of the flow passageway and toward slots  64  and  66 . A pair of wall scrapers  84  are provided for each axial flow passageways  48  and  50 , and begin at the edges  82  of water corral  80  from the inside surface of the nozzle passageway toward the outer surface at the edges of slots  64  and 
         [0042]    Condensate collecting on the inside surface of nozzle axial flow passageway  48  and  50  just before U-turns  49  and  51  is intercepted by water corral  80  and is directed to flow toward water corral edges  82  and onto wall scrapers  84 , and then toward and out of slots  64  and  66 . To promote such flow, wall scrapers  84  are angled such that there is a component of flow velocity of the cleaning medium which tends to move the liquid along the wall scrapers toward slots  64  and  66 . In other words, at slots  64  and  66 , wall scraper  84  is downstream as the cleaning medium flows as compared to its section at water corral edges  82 . Condensate which is on the lateral surfaces of axial flow passageway  40  and  50  will be intercepted by wall scrapers  84 . As mentioned previously, condensate which is on the outer surface of the axial flow passageways at U-turns  49  and  51  will be intercepted by slots  64  and  66 . 
         [0043]    Now with reference to  FIG. 9  another optional feature of slots  64  and  66  is illustrated. As shown, slot  64  can be described as having a near edge  86  and a far edge  88 . Near edge  86  is the first edge that is encountered by condensate flowing toward slot  66 . As shown, far edge  88  extends further toward the midline of the passageway and thus presents an offset upstanding wall section  88  for the enhanced interception of condensate. In one exemplary embodiment of the present invention, the offset of far edge  88  is 0.100 inch. It is expected that the effect distance is greater than 0.050 inch. 
         [0044]    A second embodiment of a nozzle in accordance with this invention is shown in  FIGS. 14A and 14B  and is generally designated by reference number  90 . Nozzle block  90  does not feature the reverse direction flow paths of the previously described embodiment and does not provide a separation between two nozzle flow paths. Instead, nozzle block  90  is a cast structure in which the inside cavity of the nozzle block  90  is restricted and causes the flow of cleaning medium to undertake an approximately 90° turn at distal end  94 . Nozzle block  90  uses some of the features provided by applicant&#39;s previously issued U.S. Pat. No. 6,764,030 (which is hereby incorporated by reference) in that it provides a smooth flow passageway for the cleaning medium to increase nozzle cleaning efficiency. 
         [0045]    Nozzle block  90  incorporates one principal feature of the present invention for the ejection of condensate; namely, slot  96 . Nozzle block  90  may feature a second nozzle outlet (not shown) positioned upstream of the distal end  94  for discharge of cleaning medium, preferably in a direction diametrically opposite the flow of medium from nozzle outlet  92 . Slot  96  is provided at the distal end at a region where the cleaning medium undergoes a high rate of change in direction and is provided at the outer surface  100  of that flow path turn. As shown best in  FIG. 14B , the cleaning medium flowing toward the right-hand direction in the figure is caused to move downwardly and undergoes a rapid change in direction in the turn toward nozzle outlet  92 . The arrows in the figures show, based on the density of the dots and speckles in the drawing signifying that the higher density fluid condensate  108  collects along the bottom surface of the passageway where is directed toward an out of slot  96 . 
         [0046]    In a manner as described previously, ejection slot  96  is provided as an ejection port for condensate. As in the case of the prior embodiment, slot  96  has a width (W) significantly less than its length (L) and the slot is cut in a manner such that its width dimension is parallel to the flow path of the cleaning medium. Accordingly, slot  96  operates in a manner of the prior embodiment in that condensate flow is interrupted by the presence of the slot and becomes ejected safely from the nozzle block. Moreover, the cross-sectional flow area of slot  96  is minimized to reduce efficiency loss in the operation of the nozzle block. The length (L) of ejection slot  96  extends to approximately the diameter of the throat  114  (minimum diameter section) of nozzle outlet  92 . Slot  96  may have a cross-sectional area about 15% of that defined by throat  114  of nozzle outlets  92 . In addition, slot  96  may have the far wall  110  offset from near wall  112 , for example by an amount of 0.100 inch. Such an offset is evident in the cross-sectional view  FIG. 14B . 
         [0047]    While the above description constitutes the preferred embodiment of the present invention, it will be appreciated that the invention is susceptible to modification, variation, and change without departing from the proper scope and fair meaning of the accompanying claims.