The present invention relates to nozzles used for the injection and atomization of black liquor that is combusted in a chemical recovery boiler.
Black liquor is a fluid that is the by product of the pulping process. This fluid contains both organic and inorganic material resulting from the pulping of wood. Black Liquor is burnt in a special boiler where the heat from the organic matter is used to generate steam and the inorganic matter is reduced to extract the pulping chemicals which are then returned to the pulping process. In order to ensure the proper combustion and chemical recovery the liquor has to be atomized to an optimum droplet size. This depends on the physical properties of the black liquor and boiler geometry as well as operating parameters such combustion air flow, liquor flow rate, injection pressure and temperature.
In accordance with the prior art, black liquor is sprayed into the boiler through dedicated nozzles.
In the case of the splash plate nozzle the black liquor is delivered through the pipe 14 which is mounted to the inlet orifice 11 on the nozzle body 13. The fluid leaves the nozzle through the discharge orifice 12. Both the inlet and discharge orifices 11 and 12 are an integral part of the nozzle body 13. The fluid upon leaving the orifice impacts on the splash plate 15 where it spreads out to form a sheet that eventually breaks up into droplets that burn.
For the V-jet nozzle 20 the fluid is delivered through pipe 24 which is mounted to the inlet orifice 21 found on the nozzle body 23. The fluid leaves the nozzle through the discharge orifice 22. Both the inlet and discharge orifices 21 and 22 are an integral part of the nozzle body 23. Fluid traveling through the discharge orifice contracts and spreads out like a fan forming a thin sheet that eventually breaks up into droplets that burn.
For the rotary atomizer/beer can nozzle 30 the fluid is delivered through pipe 34 which is mounted to the inlet orifice 31 found on the nozzle body 33. The fluid leaves the nozzle through the discharge orifice 32. Both the inlet and discharge orifices 31 and 32 are an integral part of the nozzle body 33. Fluid traveling through the inlet orifice 31 travels down a small transition channel 35 and enters the inner cavity 36 of the nozzle body 33 at a point tangential to the cavity wall. The fluid swirls around the cavity and eventually leaves the nozzle body 33 through the discharge orifice 32 found at the bottom of the nozzle body. The fluid leaving the discharge orifice spreads like a cone which eventually breaks up into droplets that burn.
In accordance with the invention, a nozzle for the spraying of black liquor in a recovery boiler is provided, where the discharge orifice of the nozzle can easily be varied without having to change the entire nozzle. This enables one to fine tune the atomization to the specific combustion setup at that time and place. The orifice height is varied to control the spray angle and characteristics to desired configurations.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements.
In order to optimize the combustion and chemical reduction it may be necessary for one to change the orifice size to vary the injection pressure or vary the flow rate. For all of the prior art nozzles above, the discharge orifice is an integral part of the nozzle body which would therefore require one to change the entire nozzle body in order to change the orifice. In another instance it may be necessary to change the orifice due to wear which results in the increase in flow area and/or change in shape. With the nozzle arrangement in accordance with the invention disclosed here one has to only change a single piece that bears the opening for the discharge orifice in order to change the orifice size.
In accordance with the invention, a nozzle arrangement is provided to enable changing of orifice properties to adjust flow and spray pattern without requiring the replacement of the entire nozzle body. This can provide lower cost operation and maintenance, for example. Further, the orifice properties may be changed to provide desired drop sizes and droplet velocities in the spray for optimum combustion in the recovery boiler.
Varying the height of the orifice insert can provide adjustment and variation to the resulting spray pattern.
Suitable dimensions in a particular embodiment include: diameter A of body, 3″, height B of body, 3.38″, diameter C of interior body cavity, 2.25″, height D of interior body cavity, 3″, based on the variation of the thickness of the orifice disk the span E can vary from 0″ to 0.45″, diameter F of interior face opening of orifice could range from, 12/32″ to 48/32″, diameter G of exterior face opening of orifice is given typically given by the relation G=F+ 3/16″, diameter H of exterior opening of body, 2.5″. Diameter D2 is slightly less than the interior diameter C interior body cavity of the beer can nozzle such that the nozzle insert may be fitted into the interior body cavity.
While in the preferred embodiment, D2 is chosen as slightly less than but very close to the diameter C of the can interior to allow insertion and removal of the insert, D2 can be varied such that D2>F+sufficient thickness to provide rigidity not collapse in use, up to D2=C−fit tolerance. Other nozzles with different sizes are also suitable. The specific dimensions may be varied depending on flow rate desired and fluid viscosity. The outer diameter B of the can should be smaller than the diameter of the opening in the boiler wall so that the can may fit into the boiler without requiring boiler modifications.
As noted, by controlling the height of the orifice (suitably by controlling the thickness of the insert orifice disk, the spray angle of the discharge spray can be controlled. Suitable values of orifice height and resulting spray angles measured are provided below.
A nozzle body in accordance with
Example 1—orifice height 4.7 mm ( 3/16 inch), orifice diameter 32 mm—spray angle 62 degrees. See
Example 2—orifice height 12 m (½ inch), orifice diameter 32 mm—spray angle 60 degrees. The spray cone appears round and well developed. Material within the spray cone appears well balanced and without noticeable weak or heavy zone. See
Example 3—orifice height 25 mm (1 inch), orifice diameter 32 mm—spray angle 54 degrees. The spray cone appears round and well developed. Material within the spray cone appears well balanced and without noticeable weak or heavy zone. See
Variation of the orifice height also has an impact on the flow rate, as measured in these examples:
Example 1—orifice diameter F, 32 mm, height 4.7 mm ( 3/16 inch), at pressure of 138 kPa (20 psig), a flow rate of 24.1 m3/h (106 GPM) was measured.
Example 5—orifice diameter F, 32 mm, height 25.4 mm (1 inch), at pressure of 138 kPa (20 psig), a flow rate of 22.9 m3/h (101 GPM) was measured.
Accordingly, the spray angle may be modified by modifying the height of the orifice through which the spray discharges from the nozzle body.
While plural embodiments of the present invention have been shown and described, it will be apparent to those skilled in the art that many changes and modifications may be made without departing from the invention in its broader aspects. The appended claims are therefore intended to cover all such changes and modifications as fall within the true spirit and scope of the invention.
This application is a continuation-in-part of U.S. patent application Ser. No. 11766030 filed Jun. 20, 2007, and claims priority from U.S. provisional patent application 60805460, filed Jun. 21, 2006.
Number | Date | Country | |
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60805460 | Jun 2006 | US |
Number | Date | Country | |
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Parent | 11766030 | Jun 2007 | US |
Child | 13089205 | US |