This invention relates to the steam generator/boiler in coal fired thermal power plants, particularly an arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure. This invention involves cleaning of ash deposition on the floor of pressure parts enclosure in the horizontal pass of the boiler where gas temperature is in the order of 900 Deg c. This invention also involves flattening of the heaps of ash formed over the floor of pressure parts enclosure during boiler operation.
BACKGROUND/PRIOR ART OF THE INVENTION
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[003] The coal based thermal power plants with two passes of gas flow and an intermittent horizontal passage of gas flow, has the potential of ash accumulation over the floor of the horizontal pass. The ash accumulated over the floor remains a concern from the safety perspective since the enclosures and supports are not usually designed for such high ash loads. Also, currently ash once accumulated is being removed manually while the boiler is shut down. Hence, utilities are forced to shut down the plants for removal of ash in this high temperature zone. In the industry, there are methods followed for
removal of soot/ash deposited over the heating surface by means of long retractable soot blowers and acoustic blowers. These are applicable to hanging pressure parts heating surfaces only. With respect to pressure parts enclosure, the industry uses wall mounted rotary blowers which blow steam to remove slags and deposits on the

vertical wall only. In all the present methods blowing equipment are used to dislodge the ash or soot stuck and the same falls by gravity. The removal of fly ash which accumulates over the floor of the pressure parts enclosure in the horizontal pass is not addressed by these methods.
[004] Now, reference may be made to the following Patents:
[005] A prior art of Patent number CN204084417U titled Boiler thermal conductive tubing ash deposition removing system, granted on 07-01-2015 discloses the method of cleaning the heat transfer bundles by means of high energy low frequency vibrators.
[006] A further prior art of Patent number CN204153794U titled Mechanical contact ash removal mechanism for high-sodium coal burning boiler back-end heating surface granted on 11-02-2015, discloses the method of removing ash from the boiler heating surface bundles by means of mechanical contact cleaning mechanism.
[007] Also, a further prior art of Patent Number US7341067B2 titled Method of managing the cleaning of heat transfer elements of a boiler within a furnace, granted on 11-03-2008 discloses a method and apparatus for measuring the effectiveness of sootblowers that remove ash deposits on the superheaters of the boilers used with the kraft pulping process.
[008] However, none of the above Patents can fulfill the requirements of present invention for which it is designed.
OBJECTS OF THE INVENTION
[009] The principal objective of this invention is to clean the ash accumulation over the floor of the pressure parts enclosure of the horizontal gas pass in a coal fired two pass boiler.

[010] Another object of the invention is to provide an arrangement in coal based two pass thermal steam generator for expelling ash deposition which uses combination of acoustic horns and air blowing nozzles to clean the ash deposition which is at high temperature in the order of 900 Deg C.
[Oil] A further object of this invention is to provide an online solution to utilities to enable them to clean the ash without shutting down the unit.
[012] These and other objects and advantages of the present invention will be apparent to those skilled in the art after a consideration of the following detailed description taken in conjunction with the accompanying drawings in which a preferred form of the present invention is illustrated.
SUMMARY OF THE INVENTION
[013] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus and a method as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be part of the claimed disclosure.
[014] The simpler solution to clean the ash accumulation over the floor of the horizontal gas pass in a two pass coal fired steam generator or boiler is by blowing pressurized air through one or more rows of nozzles inserted in the floor which blow air along the floor that is sloped towards either the first pass or the second pass of the gas flow, also, by transmitting sound waves across floor using acoustic horn placed on the sides of the floor which flattens / loosens the accumulated ash heap. The acoustic horns are operated just before the air nozzles blow the air over the floor. The expelled ash flows to the flue gas stream. This process eliminates the risk of having huge ash load in the pressure parts enclosure in the horizontal pass as well as removal of ash without shutting down the steam generator.

[015] According to this invention, there is provided an arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure comprising furnace, intermittent horizontal pass having ash over floor thereof with heating surface elements located above the floor and second pass formed by pressure parts enclosures, wherein atleast two acoustic horns are mounted on side walls above the floor so as to generate sound waves and multiple air nozzles are placed atleast in one row through the floor, which are oriented that the blowing direction aligns with that of the sloped floor.
[016] The nozzles for blowing air are placed by air blasters beneath the floor, in which the nozzles include divergent nozzles, wherein the sound waves having frequency of 60Hz to 250 Hz.
[017] The ash heaps over the floor are flattened by the intermittent blowing of acoustic horns and ash particles are pushed along the floor to j oin the flue gas stream to fall through the second pass of the boiler.
[018] The air nozzles are located in a pattern with the distance between them determined by the effectiveness of the blowing nozzle and vicinity of the boiler components and structural members.
[019] The nozzles are mounted to the connected air piping from inside of the boiler enclosure to avoid large size openings in the floor and said each air nozzle is connected to the air piping which supplies air at the required pressure.
[020] Plant service air available in the power plant suits the application and preferred range of pressure required for effective blowing is in the order of 3 to 5 bar.
[021] The nozzles are exposed to higher temperature in the order of 900 Deg C and the material for nozzle includes high grade alloy with high temperature resistance.

[022] The air inlet to the nozzles are from intermittent storage vessels with quick relief valves admitting high pressure air through the nozzles creating a blasting force at nozzle outlets in order to operate the system with controls.
[023] Any intermittent storage vessel as in air blaster system are hung from adjacent buckstay steel members in the floor to carry the self-weight of the vessels.
[024] Boiler designs have headers located beneath the floor with their supports connecting between buckstays / structural members.
[025] Various objects, features, aspects, and advantages of the inventive subject matter will become more apparent from the following detailed description of preferred embodiments, along with the accompanying drawing figures in which like numerals represent like components.
[026] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[027] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[028] The illustrated embodiments of the subject matter will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout. The following description is intended only by way of example, and simply illustrates certain selected embodiments of devices, systems, and processes that are consistent with the subject matter as claimed herein, wherein: -
Fig.l. Shows: The schematic arrangement of two pass coal fired boiler.

Fig.2. Shows: The location of acoustic horn and air nozzles according to
present invention.
Fig.3. Shows: The schematic arrangement of pressure parts enclosure in the
floor.
Fig.4. Shows: The schematic arrangement of openings in the floor for
nozzles.
Fig.5. Shows: The orientation and air blowing nozzle arrangement in
accordance with present invention.
Fig.6. Shows: The tube and membrane arrangement which forms the floor.
[029] The figures depict embodiments of the disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DETAIL DESCRIPTION OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS OF PREFERRED EMBODIMENTS
[030] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[031] The present invention makes a disclosure regarding a technology pertaining to an arrangement in coal based two pass thermal steam generator for expelling ash

deposition over the sloped floor of its pressure part enclosure. Now, reference may be made to the accompanying figures.
[032] The coal based thermal power plants are designed in various configurations. This invention particularly relates to two pass boilers where the combustion output flows vertically up in the first pass which is called as furnace (1) and the flue gas further travels horizontally over an intermittent horizontal pass (2) and further flows down through a second pass (3). The furnace (1), intermittent horizontal pass (2) and second pass (3) are usually designed to have heating surface areas (4) to pick up the heat from the flue gas. Also, the furnace (1), intermittent horizontal pass (2) and second pass (3) are formed by pressure parts enclosures. The pressure parts enclosures are usually made of steel tubes (7) welded to each other through a membrane / flat strip (10) to form a gas tight enclosure. The ash in the flue gas is usually collected at the bottom of furnace (11) and second pass through hoppers (12). The industry adopts different methods to dislodge soot or ash deposits over the heating surface (4) and vertical wall enclosures by means of blowing steam and acoustic waves. The industry currently faces the challenge of ash accumulation over the floor (5) of the intermittent horizontal pass (2). The floors (5) are usually designed with slopes less than the angle of repose of the ash and hence the ash does not slide over the floor. The gas temperature near to the floor (5) in such two pass boilers is typically in the order of 900 Deg C.
[033] The two or more acoustic horns (8) mounted on the side walls at certain height from the floor (5) level generate sound waves of frequency range. The sound waves generated travels from one side to the other side of the floor (5). The sound wave vibrates the ash particles accumulated over the floor (5). The heaps of the ash pile are loosened by the vibration and gets flattened along the floor. The heating surface (4) elements located above the floor also get vibrated to certain extent as the sound wave travels through them. The frequency of sound wave is usually in the order of 60 Hz to 250 Hz. The ash accumulation profiles in the floor of boiler pressure parts enclosure generally forms in single heap along the flue gas path. The sonic horn location has to be chosen to match such heap location.

[034] A plurality of air nozzles (9) are placed in one or more rows through the floor (5). The nozzles (9) are oriented in such a way that the blowing direction aligns with that of the sloped floor (5). The nozzles (9) blow the air intermittently at required time intervals. The blowing sequence of the nozzle starts from the row at top and follows to adjacent rows below. The boiler pressure parts enclosures are typically gas tight having tubes (7) welded to each other through membrane/ flat strip (10). To enable the air nozzles, penetrate the floor, openings (13) of required size are created for each nozzle. These openings have mounting seal boxes which hold the nozzle inlet pipes and also seals the opening to avoid leakage of flue gas. A wide variety nozzles are suitable for the application including divergent nozzles. The geometry of the nozzles (9) may vary. Nozzles (9) are mounted to the connected air piping from inside of the boiler enclosure to avoid large size openings in the floor. Each air nozzle (9) is connected to air piping which supplies air at the required pressure. Plant service air available in the power plant suits the application. Preferred range of pressure required for effective blowing is in the order of 3 to 5 bar. High pressure air pushing the ash particles over the surface of the tubes may lead to erosion of the metal surface. Hence, the pressure is maintained to minimum level without compromising the effectiveness. The nozzles are exposed to higher temperature in the order of 900 Deg C. Hence, the material for nozzle (5) is of high grade alloy with high temperature resistance. The boiler pressure parts enclosure especially the floor has many mountings and attachments including major structural members like buckstay beams (6) which strengthen the floor (5). The nozzle (9) locations are chosen in such a way that the mounting arrangement of air nozzles have sufficient clearance with this structural arrangement (6). In order to operate the system with controls, the air inlet to the nozzles are from intermittent storage vessels with quick relief valves admitting high pressure air through the nozzles creating a blasting force at nozzle outlets. Such air blasters with air preparation units can be installed with required controls to operate the system. The boiler pressure parts enclosure expands during operation. Hence the mounting of nozzle also moves during operation. Any intermittent storage vessel as in air blaster system are hung from adjacent buckstay steel members in the floor to carry the self-weight of the

vessels. The blowing reactions on to the frame are resolved to arrive at effective load transfer on the enclosure and steel structures and verified for the required strength. The distance between adjacent nozzles (9) within a row is influenced by the effectiveness of the nozzle (9) and the location of structural attachment (6) in the floor (5). Boiler designs have headers located beneath the floor with their supports connecting between buckstays / structural members (6). While determining the number of nozzles and distance between them arrangement of header (14) is reviewed for the feasibility to mount without compromising the effectiveness of cleaning.
[035] For the safe operation of the units, to avoid any unintended post combustion of unburnt fuel present in the horizontal pass due to failed startups or interrupted operations the following are recommended.
[036] The cleaning procedure shall be executed before every start up in cold conditions as a process of purging. Also, the cleaning procedure should not be executed just immediately after any trip or failed start up where high temperature may prevail. Under such circumstances the cleaning procedure shall be executed only after a stable period of operation.
[037] The distinguishing features of the present invention over the prior arts are as follows:-
[038] The prior art of Patent number CN204084417U titled Boiler thermal conductive tubing ash deposition removing system, granted on 07-01-2015 discloses the method of cleaning the heat transfer bundles by means of high energy low frequency vibrators. Whereas the current invention discloses method of cleaning ash on the floor of enclosure not the heat transfer bundles.
[039] Further prior art of Patent number CN204153794U titled Mechanical contact ash removal mechanism for high-sodium coal burning boiler back-end heating surface granted on 11-02-2015, discloses the method of removing ash from the boiler heating surface bundles by means of mechanical contact cleaning

mechanism. Whereas the current invention discloses the method of using air blowing nozzles and acoustic horns to clean the floor of boiler pressure parts enclosure without involving mechanical contact.
[040] Further prior art of Patent Number US7341067B2 titled Method of managing the cleaning of heat transfer elements of a boiler within a furnace, granted on 11-03-2008 discloses a method and apparatus for measuring the effectiveness of sootblowers that remove ash deposits on the superheaters of the boilers used with the kraft pulping process. Whereas the current invention discloses method which does not involve sootblowers for heat transfer elements and not related to measuring of sootblower effectiveness.
[041] The current invention is different from these prior arts as it discloses the method of removing accumulated ash on the sloped pressure parts enclosure not the heating surface elements. Also, the method is different by using a combination of acoustic horn and air blowing nozzles fitted on to the floor.
[042] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the "invention" may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the "invention" will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[043] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability. When any such inclusion or deletion occurs, the specification is herein deemed to contain the group as modified thus fulfilling the written description of all groups used in the appended claims.

[044] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particulars claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to "at least one of A, B, or C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but

not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B".
[045] The above description does not provide specific details of manufacture or design of the various components. Those of skill in the art are familiar with such details, and unless departures from those techniques are set out, techniques, known, related art or later developed designs and materials should be employed. Those in the art are capable of choosing suitable manufacturing and design details.
[046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. It will be appreciated that several of the above-disclosed and other features and functions, or alternatives thereof, may be combined into other systems or applications. Various presently unforeseen or unanticipated alternatives, modifications, variations, or improvements therein may subsequently be made by those skilled in the art without departing from the scope of the present disclosure as encompassed by the following claims.
[047] The claims, as originally presented and as they may be amended, encompass variations, alternatives, modifications, improvements, equivalents, and substantial equivalents of the embodiments and teachings disclosed herein, including those that are presently unforeseen or unappreciated, and that, for example, may arise from applicants/patentees and others.
[048] While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are

not intended to be limiting, with the tme scope and spirit being indicated by the following claims.

We claim

1.An arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure comprising furnace (1), intermittent horizontal pass (2) having ash over floor (5) thereof with heating surface (4) elements located above the floor (5) and second pass (3) formed by pressure parts enclosures, wherein atleast two acoustic horns (8) are mounted on side walls above the floor (5) so as to generate sound waves and multiple air nozzles (9) are placed atleast in one row through the floor (5), which are oriented that the blowing direction aligns with that of the sloped floor (5).
2. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in claim 1, wherein the nozzles (9) for blowing air are placed by air blasters beneath the floor (5), in which the nozzles (9) include divergent nozzles, wherein the sound waves having frequency of 60Hz to 250 Hz.
3. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in the claim 1 or 2, wherein the ash heaps over the floor (5) are flattened by the intermittent blowing of acoustic horns (8) and ash particles are pushed along the floor (5) to join the flue gas stream to fall through the second pass (3) of the boiler.
4. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in the claims 1-3, wherein the air nozzles (9) are located in a pattern with the distance between them determined by the effectiveness of the blowing nozzle and vicinity of the boiler components and structural members (6).

5. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in the claims 1-4, wherein the nozzles (9) are mounted to the connected air piping from inside of the boiler enclosure to avoid large size openings in the floor and said each air nozzle (9) is connected to the air piping which supplies air at the required pressure.
6. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in the claims 1-5, wherein plant service air available in the power plant suits the application and preferred range of pressure required for effective blowing is in the order of 3 to 5 bar.
7. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in the claims 1-6, wherein the nozzles are exposed to higher temperature in the order of 900 Deg C and the material for nozzle (5) includes high grade alloy with high temperature resistance.
8. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in the claims 1-7, wherein the air inlet to the nozzles are from intermittent storage vessels with quick relief valves admitting high pressure air through the nozzles creating a blasting force at nozzle outlets in order to operate the system with controls.
9. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in the claims 1-8, wherein any intermittent storage vessel as in air blaster system are hung from adjacent buckstay steel members in the floor to carry the self-weight of the vessels.

10. The arrangement in coal based two pass thermal steam generator for expelling ash deposition over the sloped floor of its pressure part enclosure as claimed in the claims 1-9, wherein boiler designs have headers located beneath the floor with their supports connecting between buckstays / structural members (6).