DESC:‘IMPROVED BLAST DISTRIBUTION SYSTEM FOR UNIFORM DISTRIBUTION OF BLAST IN UPDRAFT FIXED BED GASIFIER’

FIELD OF INVENTION:
[001] The field of invention generally relates to gasification. The field of invention particularly relates to process of producer gas generation. The present invention avoids wall clinker formation in updraft producer gas gasifier thereby avoiding frequent failure of operating producer gas gasifier, maximizing the producer gas generation and reducing unburnt coal in ash.

BACKGROUND 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 Producer gas is obtained from gasification of coal in presence of blast (air and steam mixture) in a fixed bed updraft gasifier. In the fixed bed updraft gasifier, the coal is fed from the top of the gasifier and blast is injected from the bottom of the gasifier. Inside the gasifier different zones of chemical reaction takes place in presence of a fire bed. The zones are ash zone, oxidation zone, reduction zone, pyrolysis zone and drying zone. The coal is charged inside the gasifier when the outlet gas temperature reaches a temperature of around 350 deg celcius. The coal passes towards bottom of the gasifier through different zones of chemical process. A mixture of air and steam called blast is injected through the grate rings from the bottom of the gasifier unit. The air and steam mixture from grate rings passes upward through the coal fire bed using the porous nature of the coal bed.

[004] Due to oxidation and followed by reduction reaction producer gas is being generated. The constituents of producer gas are Carbon monoxide, Hydrogen, Methane, less than 0.4 percent of oxygen, 4-6 percent of carbon dioxide and rest 45-50 percent of Nitrogen.

[005] The present grate ring assembly used in the fixed bed updraft gasifier is at the center of the gasifier and is around 0.6 meter in diameter and contained within the ash zone. The blast from the grate ring assembly further passes through the coal fire bed of gasifier which is around 3.0 meter in diameter and 2.0 meter in height. Hence, the present grate ring assembly is only 1/5th of the diameter of the gasifier.

[006] The passage of blast from ash zone to the oxidation zone and reduction zone enables the oxidation zone where heat is being released continuously from the exothermic reaction, to be maintained at around 1000 to 1200 degree Celsius. Hence uniform distribution of blast through coal fire bed is essential to maintain the temperature of the oxidation zone.

[007] Non uniform distribution of blast leads to uncontrolled exothermic reaction in the oxidation zone leading to temperatures of above 1450 degree Celsius where ash fusion occurs and forms clinkers. The clinkers create solid mass of coal bed instead of porous bed.

[008] The present grate ring assembly is only 1/5th of the diameter of the gasifier and hence the blast distribution is majorly concentrated at the center of the gasifier. The outer periphery of gasifier receives only minimum portion of blast and hence it leads to excessive clinker formation in the walls of the gasifier. The wall clinkers stick to the walls and are difficult to be poked and broken, to again form a porous coal fire bed. Since the walls are formed with clinkers, the effective area of gasification gets reduced leading to reduced volume of producer gas generation from the gasifier. Subsequently the wall clinkers gradually extend from the periphery to the center of the gasifier and finally completely blocks the passage of blast from the grate rings assembly leading to shutdown/failure of the operating producer gas gasifier.
[009] Hence there is need for optimizing the blast distribution through grate ring assembly to enable uniform distribution of blast throughout the 3.0meter diameter of gasifier to eliminate the drawback described above.

[0010] In view of the above, present invention has been introduced.

OBJECTS OF THE INVENTION:
[0011] An object of the invention is to propose an Improved blast distribution system for uniform distribution of blast in updraft fixed bed gasifier.

[0012] Another object of the invention is to propose Improved blast distribution system for uniform distribution of blast in updraft fixed bed gasifier, which obviates drawbacks of the prior art(s).

[0013] Still another object of the invention is to propose Improved blast distribution system for uniform distribution of blast in updraft fixed bed gasifier, which is simple in construction.

[0014] 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:

[0015] One or more drawbacks of conventional systems and process are overcome, and additional advantages are provided through the apparatus/composition 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.

[0016] According to the present invention, there is provided an improved blast distribution system for uniform distribution of blast in updraft fixed bed gasifier comprising of Ash Zone (1), Oxidation zone (2), Reduction zone (3), pyrolysis zone and drying zone (4) connected to each other and in flow communication sequentially, in which blast is injected through a grate ring assembly (6) at the bottom of the system.

[0017] In the Ash zone (1) the blast (Air and steam mixture) is injected, which gets preheated and passes to the oxidation zone (2) and the temperature of the oxidation zone (2) is 1000 to 1200 degree Celsius.

[0018] In the oxidation zone (2), hot carbon dioxide is formed by the reaction of carbon and oxygen of air, in which the carbon burns in the lower part of the gasifier by exothermic reactions leading to generation of heat.

[0019] The layer of coal is heated up to more than 1000 degree Celsius by the amount of heat set free during the reaction, in which in the reduction zone (3), subsequent reactions occur which produce carbon monoxide, carbon dioxide, hydrogen and methane.

[0020] In the pyrolysis and drying zone (4), water vapour and volatile matter of the fuel are added to the gas, in which drying of the charged coal, done through coal charging inlet (7), occurs in this region, and as the gas travels through the bed, its composition goes on changing at each point and the addition of volatile matter increases the calorific value of the exit gas which passes through the producer gas outlet (5) for gas washing and cooling.

[0021] The grate ring assembly (6) is 3.0 to 3.3 times in diameter of existing assembly and 3/5th to 2/3rd of the diameter of the gasifier, wherein the blast distribution is even and uniform and enables steam injection in the entire diameter of the gasifier which is 3.0 meter.

[0022] 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.

[0023] 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.

[0024] 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 DRAWING:
[0025] 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:
Figure 1 shows: gasification process with improved blast distribution system for uniform distribution of blast throughout the gasifier and also unburnt coal in the ash is reduced, which indicates as follows:
1 - Ash Zone
2 - Oxidation Zone
3 - Reduction Zone
4 - Pyrolysis and Drying Zone
5 - Producer Gas outlet
6 - Grate ring assembly for blast distribution

[0026] 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:

[0027] 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.

[0028] The present invention makes a disclosure regarding a technology pertaining to an invention directing to improved blast distribution system for uniform distribution of blast in updraft fixed bed gasifier.

[0029] Here, the gasifier converts the coal into producer gas by different zones of chemical reaction in the gas generator. Different reactions occur at different zones of the bed such as: Ash Zone (1), Oxidation zone (2), Reduction zone (3), pyrolysis zone and drying zone (4).

[0030] In the Ash zone (1) the blast (Air and steam mixture) is injected, gets preheated and further passes to the oxidation zone (2). The temperature of the oxidation zone is around 1000 degree to 1200 degree Celsius. In the oxidation zone (2), hot carbon dioxide is formed by the reaction of carbon and oxygen of air. Due to sufficient air from blast, the carbon burns completely in the lower part of the gasifier by exothermic reactions leading to generation of heat. The layer of coal is heated up to more than 1000 deg. Celcius by the amount of heat set free during above reaction. In the reduction zone (3), subsequent reactions occur which produce carbon monoxide, carbon dioxide, hydrogen and methane.

[0031] The top most zone is the pyrolysis and drying zone (4) where water vapour and volatile matter of the fuel are added to the gas. Also drying of the charged coal, done through coal charging inlet 7, occurs in this region. Hence, it is observed that, as the gas travels through the bed, its composition goes on changing at each point. The addition of volatile matter increases the calorific value of the exit gas which finally passes through the producer gas outlet (5) for gas washing and cooling.

[0032] The oxidation zone 2 of the gasifier being exothermic, there is danger that the ash could melt due to the high temperature forming. Since the steam is parallelly admitted in the hot carbon layer, it generates carbon monoxide and hydrogen gas by endothermic reactions in reduction zone 3. As this reaction uses heat, temperature inside the gasifier is lowered and maintained and is maintained mainly around the center of the gasifier. However in the periphery of the gasifier, since steam admission is minimum the high temperature forming is unavoidable leading to wall clinker formation.

[0033] The present invention comprises of improved blast distribution system in the updraft fixed bed gasifier by injection of blast through a new grate ring assembly (6) which is 3.0 to 3.3 times in diameter instead of present diameter of 0.6 meter. The new grate ring assembly is 3/5th to 2/3rd of the diameter of the gasifier and hence the blast distribution is even and uniform and enables steam injection in the entire diameter of the gasifier which is 3.0 meter. Hence the steam cools down the complete coal fire zone due to its endothermic reactions and prevents the fusion of the ash, formation of clinkering and channeling throughout the gasifier including the walls thereby avoiding wall clinker formation leading to frequent failure of operating producer gas gasifier. It gives a good and granulated ash from the gasifier since uniform and even distribution of air is ensured. This ensures increased reaction of blast with coal which in turn delivers maximum quantity of producer gas from the gasifier and also unburnt coal in the ash is reduced leading to coal savings.

[0034] From the above, working of the invention can be understood clearly.

ADVANTAGES OF THE INVENTION:

- The even and uniform distribution of blast prevents the fusion of the ash, formation of clinkering and channelling throughout the gasifier including the walls thereby avoiding frequent failure of operating producer gas gasifier;

- It gives a good and granulated ash from the gasifier since uniform and even distribution of air is ensured. This ensures increased reaction of blast with coal which in turn delivers maximum quantity of producer gas from the gasifier and also unburnt coal in the ash is reduced leading to coal savings;

- Simple in construction;

- User Friendly.

TEST RESULT:

[0035] The increase in extent of gasification along the walls of the gasifier leads to more effective conversion of coal along the gasifier walls and also results in lesser percentage of unburnt coal in coal ash.

Features and Reference Numerals in Fig. 1

Sl.No. Number Description
1 1 Ash Zone
2 2 Oxidation Zone
3 3 Reduction Zone
4 4 Pyrolysis and Drying Zone
5 5 Producer Gas outlet
6 6 2.0 meter diameter Grate ring assembly for blast distribution

[0036] 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.

[0037] 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.

[0038] 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 analogues 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”.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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 true scope and spirit being indicated by the following claims.
,CLAIMS:WE CLAIM:

1. An improved blast distribution system for uniform distribution of blast in updraft fixed bed gasifier comprising of Ash Zone (1), Oxidation zone (2), Reduction zone (3), pyrolysis zone and drying zone (4) connected to each other and in flow communication sequentially, in which blast is injected through a grate ring assembly (6) at the bottom of the system.

2. The improved blast distribution system for uniform distribution of blast as claimed in claim 1, wherein in the Ash zone (1) the blast (Air and steam mixture) is injected, which gets preheated and passes to the oxidation zone (2) and the temperature of the oxidation zone (2) is 1000 to 1200 degree Celsius.

3. The improved blast distribution system for uniform distribution of blast as claimed in claim 2, wherein in the oxidation zone (2), hot carbon dioxide is formed by the reaction of carbon and oxygen of air, in which the carbon burns in the lower part of the gasifier by exothermic reactions leading to generation of heat.

4. The improved blast distribution system for uniform distribution of blast as claimed in claims 1-3, wherein the layer of coal is heated up to more than 1000 degree Celsius by the amount of heat set free during the reaction, in which in the reduction zone (3), subsequent reactions occur which produce carbon monoxide, carbon dioxide, hydrogen and methane.

5. The improved blast distribution system for uniform distribution of blast as claimed in claims 1-4, wherein in the pyrolysis and drying zone (4), water vapour and volatile matter of the fuel are added to the gas, in which drying of the charged coal, done through coal charging inlet (7), occurs in this region, and as the gas travels through the bed, its composition goes on changing at each point and the addition of volatile matter increases the calorific value of the exit gas which passes through the producer gas outlet (5) for gas washing and cooling.

6. The improved blast distribution system for uniform distribution of blast as claimed in claim 1, wherein the grate ring assembly (6) is 3.0 to 3.3 times in diameter of existing assembly and 3/5th to 2/3rd of the diameter of the gasifier, wherein the blast distribution is even and uniform and enables steam injection in the entire diameter of the gasifier which is 3.0 meter.