Optimized Overfire Air Nozzles, System and Strategy

Abstract

Nozzles for delivering air into a combustion system of a boiler including an interchangeable nozzle barrel. Nozzle barrels can be easily replaced for maintenance or to change the size and flow velocity of the nozzles to optimize combustion performance. Nozzles may include converging sections with an arc, double arc's, bell shaped, or hyperbolic curves around the entire perimeter of the nozzle and optimized for delivery of air into the combustion system from ducting or from within a plenum.

Claims

1. A strategy to optimize overfire air delivery into a combustion system, pair, set or somewhat like combustion systems whereby interchangeable nozzle barrels are used to determine the optimal nozzle size, quantity, location, and arrangement.

2. Systems comprised of multiple nozzles, some or all of which with interchangeable nozzles and subsequent systems comprised of all, some, or no interchangeable nozzles, but based on prior said system and findings.

3. Overfire air nozzles for delivering air into a combustion system comprising: a. A removable, replaceable, and/or interchangeable nozzle barrel with, without, or with a portion of the converging section. b. A removable section, spool piece, access panel, etc. to aid in replacement of said interchangeable nozzle. c. A site port and/or rod-out port for observing and/or removing slag build up. d. A connection for a test port, pressure gauge, and/or pressure transmitter. e. Transitions, elbows, reducers, connections, etc. which are smooth and without obstruction to provide for a good flow path. f. A converging section which is straight and angled and/or with curves around the entire perimeter to optimize the converging section, for example a hyperbolic bell shape. Converging section may also be the entrance to the nozzle whose shape is optimized as an entrance and as a converging section and may be within an open section of duct, wind box, plenum, etc.

Description

DESCRIPTION OF THE DRAWINGS

[0007] Some embodiments of the Optimized Overfire Air Nozzles are illustrated as examples and are not limited by the figures of the attached drawings, in which like references may indicate similar elements.

[0008] FIG. 1 depicts a cross-sectional view of one OOA Nozzle (usually of a multitude), utilizing a cone shaped converging section and an overhead duct, according to one embodiment.

[0009] FIG. 2 depicts a cross-sectional view of one OOA Nozzle (usually of a multitude) utilizing a bell-shaped entrance and/or converging section within a plenum, according to one embodiment.

DETAILED DESCRIPTION OF THE OPTIMIZED OVERFIRE AIR NOZZLES

[0010] Various embodiments and aspects of OOA will be described with reference to details discussed within this application, and the accompanying drawings will illustrate the various embodiments. The following description and drawings are illustrative of OOA and are not to be construed as limiting. Specific details are described to provide a thorough understanding of the various embodiments. However, in certain instances, well-known or conventional details are not described in order to provide a concise discussion of the embodiments of OOA.

[0011] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used here I, the singular forms of “a,” “an,” and “the” are intended to include the plural forms as well as the singular forms, unless the context clearly indicates otherwise. It shall be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof.

[0012] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one having ordinary skill in the art to which this invention belongs. It will be further understood that terms such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and present disclosure and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0013] In describing the invention, it will be understood that a number of techniques and steps are disclosed. Each of these has individual benefit and each can also be used in conjunction with one or more, or in some cases all, of the other disclosed techniques. Accordingly, for the sake of clarity, this description will refrain from repeating every possible combination of the individual steps in an unnecessary fashion. Nevertheless, the specification and claims should be read with the understanding that such combinations are entirely within the scope of the invention and claims.

[0014] FIGS. 1 and 2 show embodiments of the Optimized Overfire Air Nozzle as being round in cross-section, round is ideal, but virtually any cross-section can be used. For example, an oval shape to better fit the tube-bend openings of a boiler wall. FIG. 2 shows the converging section as curved around the entire round perimeter (bell shaped), this is ideal, but a simpler straight converging section can be used as in FIG. 1.

[0015] FIG. 1 shows one embodiment of an Optimized Overfire Air Nozzle being fed combustion air by a duct 7. From the duct the air is transitioned from vertical to horizontal, to a converging section 2 where the flow is accelerated, then to a nozzle barrel 3. The flow path of the transition and converging section are as smooth as practical, and the nozzle barrel sufficiently long so as to pass through the furnace skin, casing, refractory and/or boiler tube openings 10,11 and to produce a good jet of air entering the furnace. There is an access port 6 adjacent to the nozzle barrel so that build-up can be removed, usually with a long rod, the port is often fitted with high temperature glass so that buildup, corrosion, and furnace conditions can be easily monitored. The embodiment in FIG. 1 shows one possible method for changing or replacing nozzles where the elbow and most of the converging section is a spool piece 1,2 that is first disconnected from the upstream duct and the downstream nozzle to give adequate space for the nozzle to be removed.

[0016] FIG. 2 shows one embodiment of an Optimized Overfire Air Nozzle being fed combustion air by a plenum 8 which feds air to multiple nozzles. The plenum could be an air/wind box, basically anything with a large open area or duct usually meant for distributing air to multiple ports or multiple areas on a furnace/boiler by which the nozzle is connected to or fits within. The embodiment in FIG. 2 show another possible method for changing or replacing nozzles where the access panel 1 is removed to allow for adequate space for the nozzle to be removed. Attached to the access panel is the sight/rod-out port 6 for monitoring and removing build-up. Nozzles could alternatively be easily fitted with automatic buildup removal, port-rodders.

[0017] The combustion air doesn't have to be air, it can be any gas used for combustion, or a mixture of gas and air, entrained combustible particulate, etc. There can be a sleeve which the interchangeable nozzle barrel fits within, but the sleeve is not always necessary and is often the largest nozzle for a given application. Small changes to the flow area of the nozzle barrel can result in large changes in combustion, often the interchangeable barrels are simply different thicknesses, smaller ID for a small change in the flow area. Varying barrel thickness can also be used for corrosion control. The connections 5 shown are simple bolted flanges, but there are many possibilities for different connection types. Likewise, the mount 9 is a simple stub welded to the furnace casing 10, but the nozzle/assembly could be mounted many different ways.

[0018] Mounted upstream of the nozzle barrel is a connection 7 for a test port, pressure gauge and/or pressure transmitter that can be used for tuning, control and/or determining the rate of flow through the nozzle(s).

[0019] The interchangeable/replaceable nozzle barrel can include all of the converging section, a portion of the converging section, none of the converging section and/or separate interchangeable converging sections. The nozzle barrel could also have a simple taper at the entrance to transition to the converging section for small changes in barrel size. A perfect transition may be sacrificed for simpler interchangeability.

[0020] Often OOA will be used to determine the optimal nozzle size then copied for other similar boilers, simpler design, not necessarily interchangeable or as replaceable. This patent is meant to also apply to these simpler, subsequent designs when derived from an Optimized Overfire Air System and Strategy.