DESC:FIELD
The present disclosure relates to the field of boilers.
BACKGROUND
Nowadays, some industrial boilers employ the use of integral furnaces that can be used for the combustion of solid fuels. A conventional integral furnace may defined in the shell of the boiler itself and has a cylindrical configuration. A stationary grate is disposed within the integral furnace. The stationary grate acts as a combustion bed for the combustion of solid fuel. The stationary grate is disposed within the integral furnace in a manner such that a combustion space is formed operatively above the stationary grate and a hollow space is formed operatively below the stationary grate. A combustion medium for the combustion of solid fuel, which is generally hot air, is introduced into the combustion space via the hollow space. Furthermore, convective tubes are disposed in the cylindrical shell. The convective tubes are configured to allow the flow of flue gases therethrough, formed due to the combustion of the solid fuel. The heat contained in the flue gases can be used for steam generation. The drawback of this integral furnace is that the hollow space formed operatively below the stationary grate is an un-utilized space which cannot be used for the combustion of the solid fuel. As such, the hollow space reduces the usable volume of the integral furnace. Thus, the effective furnace volume, for combustion of a unit quantity of the solid fuel, is reduced.
In case, a greater quantity of a solid fuel needs to be combusted, the size of the integral furnace needs to be increased. This causes an increase in the cost.
In small scale industries, where a boiler is required to be operated intermittently, a large sized boiler becomes un-affordable. The conventional integral furnace is not adequately lined with a refractory. The heat retention within the conventional integral furnace is also low. Therefore, more time is required for combustion during the start of a next cycle, i.e., there is delay in start-up.
There is a need for a boiler having an integral furnace that can combust large quantities of solid fuel. Furthermore, there is need for a boiler having an integral furnace that requires less time for start up.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is to provide a boiler having an integral furnace for the combustion of solid fuel that has an optimal configuration capable of combusting larger quantities of solid fuel.
Another object of the present disclosure is to provide a boiler having an integral furnace for combustion of solid fuel that has low water holdup resulting in less time for start up.
Yet another object of the present disclosure is to provide a boiler having an integral furnace for combustion of solid fuel that can combust various types of solid fuel and use different type of combustors.
Still another object of the present disclosure is to provide a boiler having an integral furnace for combustion of solid fuel that is cost effective.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages a boiler. The boiler comprises a shell that is defined by a first portion and a second arcuate portion extending from the first portion. The first portion has a cylindrical configuration and houses a first plurality of tubes. The second arcuate houses a second plurality of tubes such that the first plurality of tubes and the second plurality of tubes are in fluid communication. A pair of supports is configured to support the shell and is disposed operatively below the shell in a spaced apart configuration. A grate is disposed and supported operatively between the pair of supports and operatively below the second arcuate portion such that the pair of supports and the second arcuate portion define a combustion space for the combustion of fuel. The flue gases formed due to the combustion of fuels on the grate enter the first plurality of tubes and the second plurality of tubes for use as a heat source for production of steam.
The boiler includes a reversal chamber disposed adjacent the shell and in fluid communication with the first plurality of tubes and the second plurality of tubes such that the flue gases from the first plurality of tubes enter the reversal chamber and exit the reversal chamber to enter the second plurality of tubes.
Further the boiler includes a heat recovery unit in fluid communication with the second plurality of tubes and configured to receive the flue gases from the second plurality of tubes. The remnant heat of the flue gases of the flue gases is utilized to pre-heat the feedwater entering the boiler.
The pair of supports is provided with a refractory lining at an operative inner surface thereof to facilitate the retention of heat within the combustion space.
The grate is selected from a group consisting of a stationary grate, an underfeed stroker, a chain grate, and a reciprocating grate.
The boiler includes a blower disposed operatively below the first portion and configured to supply air to the grate to facilitate the combustion of fuel thereon.

BRIEF DESCRIPTION OF ACCOMPANYING DRAWING
An integral furnace will now be described with the help of non-limiting accompanying drawing in which:
Figure 1 illustrates a schematic view of a boiler having a conventional integral furnace for combustion of solid fuel;
Figure 2 illustrates an isometric view of a boiler having an integral furnace for combustion of solid fuel, in accordance with an embodiment of the present disclosure;
Figure 3 illustrates an isometric view of a shell of the integral furnace of Figure 2;
Figure 4 illustrates a sectional view of the boiler of the Figure 2; and
Figure 5 illustrates an isometric view of the boiler of the Figure 2.
LIST OF REFERENCE NUMERALS USED IN THE DESCRIPTION AND DRAWING
100 – Conventional boiler
102 – Cylindrical shell
104 – Conventional integral furnace
106 – Stationary grate
108 – Combustion space
110 – Hollow space
112 – Plurality of convective tubes
200 – Boiler
202 – Integral furnace
204 – Pair of supports
206 – Grate
208 – Shell
210 – First plurality of tubes
212 – Second plurality of tubes
214 – Reversal chamber
216 – Smoke chamber
218 – Heat recovery unit
220 – Second arcuate portion/Heat transfer zone
222 – First portion/Furnace zone
224 – Coil inserts
226 – Fire door
228 – Blower
DETAILED DESCRIPTION
Figure 1 illustrates a schematic view of a boiler 100 having a conventional integral furnace for the combustion of solid fuels. The boiler 100 has a cylindrical shell 102. A conventional integral furnace 104 (hereinafter referred to as furnace 104) is defined by the inner periphery of the cylindrical shell 102 and a stationary grate 106 disposed therewithin. The stationary grate 106 acts as a combustion bed for the boiler 100. The stationary grate 106 is disposed in a manner such that a combustion space 108 is formed operatively above the stationary grate 106, and a hollow space 110 is formed operatively below the stationary grate 106. A combustion medium for the combustion of the solid fuel, which is generally normal or preheated air, is introduced into the combustion space 108 via the hollow space 110. The boiler 100 further comprises a plurality of convective tubes 112 disposed in the operative upper portion thereof. The plurality of convective tubes 112 is configured to allow the flow of flue gases therethrough, which are formed due to the combustion of solid fuel. The heat contained in the flue gas can be used for steam generation. The drawback of the furnace 104 is that the hollow space 110 formed operatively below the stationary grate 106 cannot be utilized for fuel combustion. This reduces the effective usable combustion volume and residence time for combustion of the fuel inside the furnace 104 of the boiler 100. Furthermore, to provide higher combustion volume and residence time, the volume of the furnace 104 has to be increased, which can only be done by manufacturing a furnace with a larger configuration, thereby resulting in larger size and higher costs.
The present disclosure envisages a boiler having an integral furnace that has an optimized usable volume. More specifically, the present disclosure envisages a boiler having an integral furnace that even in a smaller configuration can provide large combustion volume and residence time for solid fuel combustion therewithin.
Figure 2, Figure 3, Figure 4, and Figure 5 illustrate different views of a boiler 200 and an integral furnace 202 (hereinafter referred to as furnace 202). The boiler 200 comprises a pair of supports 204, a grate 206 that is disposed operatively between the pair of supports 204, a shell 208 (also known as a pressure element or a pressure part) disposed operatively above the pair of supports 204, a first plurality of tubes 210 disposed within the shell 208, a second plurality of tubes 212 disposed within the shell 208, a reversal chamber 214 disposed adjacent to the shell 208 wherein the reversal chamber 214 is in fluid communication with the shell 208, a smoke chamber 216 that is in fluid communication with the shell 208, and a heat recovery unit 218.
The shell 208 is defined by a first portion 222 and a second arcuate portion 220 extending from the first portion 222. The first portion 222 has a cylindrical configuration and houses the first plurality of tubes 210. The second arcuate portion 220 houses a second plurality of tubes 212 such that the first plurality of tubes 210 and the second plurality of tubes 212 are in fluid communication via the reversal chamber 214. The reversal chamber 214 is disposed adjacent the shell 208 and in fluid communication with the first plurality of tubes 210 and the second plurality of tubes 212 such that the flue gases from the first plurality of tubes 210 enter the reversal chamber 214 and exit the reversal chamber 214 to enter the second plurality of tubes 212.
The pair of supports 204 is configured to support the shell 208 and is disposed operatively below the shell 208 in a spaced apart configuration. The pair of supports 204 is lined, at an operative inner surface thereof, with a refractory 204a that retains heat within the furnace 202 and helps in frequent on-off situation.
The grate 206 is disposed and supported operatively between the pair of supports 204 and operatively below the second arcuate portion 220 such that the pair of supports 204 and the second arcuate portion 220 define a combustion space or the integral furnace 202 for the combustion of fuel. The flue gases formed due to the combustion of fuels on the grate 206 enter the first plurality of tubes 210 and the second plurality of tubes 212 for use as a heat source for production of steam. Unlike the conventional furnace 104, the furnace 202 of the present disclosure is not an enclosed space and is accessible from the operative bottom thereof. As the furnace 202 is open from its operative bottom portion, in accordance with an embodiment, different types of combustion beds may be used, e.g., a stationary grate, an underfeed stroker, a chain grate, a reciprocating grate, and the like. The use of a chain grate or a reciprocating grate facilitates the automated movement of the grate 206. Thus, a flexibility in the type of combustion bed that can be used is obtained in the boiler 200 of the present disclosure. The use of different types of the combustion beds also facilitates the usage of different types of fuel.
The shell 208 is supported on the pair of supports 204. The cross-sectional configuration of the shell 208 is seen in Fig. 3. As seen in Fig. 3, the shell 208 has a split semi-circular cross-sectional configuration that extends along a pre-determined length of the shell 208. This split semi-circular cross-sectional configuration defines a furnace zone 220 (also referred to as the second arcuate portion 220). The remaining portion of the shell 208 has a circular cross-sectional configuration, and it defines a heat transfer zone 222 (also referred to as first portion 222). As seen in Figure 2 and Figure 3, due to the semi-circular cross-sectional configuration of the furnace zone 220, the effective usable volume available for the combustion of the solid fuel is more in the furnace 202, as compared with conventional furnace 104. More specifically, the semi-circular or the arcuate configuration of the furnace zone 220 or the second arcuate portion 220 supported on the pair of supports 204 provides an open space for accommodating the grate 206, unlike the conventional integral furnace 104 where the conventional integral furnace was defined in an enclosed space with the cylindrical shell 102. Thus, for a smaller size, the effective usable volume for the combustion of fuel is more in the furnace 202 of the present disclosure, as compared with that of the furnace 104. Thus, the cost associated with the manufacturing of furnace 202 is reduced since the need of manufacturing a larger sized boiler is overcome.
Referring to Figure 4, the boiler 200 comprises the first plurality of tubes 210 disposed within the heat transfer zone 222 of the shell 208 and the second plurality of tubes 212 that is disposed within the shell 208 operatively above the heat transfer zone 222 and extending long the length of the shell 208. The flue gases formed in the furnace zone 220 of the shell 208 are then passed through the first plurality of tubes 210 in the heat transfer zone 222 where the heat transfer between the flue gas and the fluid contained in the shell side of the heat transfer zone 222, and the fluid is substantially evaporated. Thereafter, the flue gases pass through the reversal chamber 214 that is in fluid communication with the first plurality of tubes 210 and the second plurality of tubes 212. The direction of travel of the flue gases is reversed in the reversal chamber 214, and the flue gas re-enters the second plurality of tubes 212 that extend along the length of the shell 208. The plurality of flue gas tubes 212 includes coil inserts 224 inserted therewithin to enhance the heat transfer by increasing the surface area as well as the retention of the flue gas within the tubes. The flue gases further enter the heat recovery unit 218 where the remnant heat contained in the flue gases is transferred to the fluid contained in the heat recovery unit 218, thereby utilizing said heat to pre-heat the fluid being supplied to the boiler. The fluid is generally water, and as such, the heat obtained by the flue gases inside the heat recovery unit 218 is utilized to pre-heat the feedwater supplied to the boiler 200. The heat recovery unit 218 is coupled to a feed water pump and a vent line can be connected to a feed water tank. If the heat recovery unit 218 gets pressurised due to steaming, water is vented to the feed water tank to relieve pressure.
In one embodiment, as seen in Figure 4 and Figure 5, a fire door 226 is provided on the boiler 200 to facilitate input of fuel and removal of ash. A blower 228 is disposed in the operative lower portion of the boiler 200, preferably operatively below the first portion 222. The blower 228 supplies air to the grate 120 to facilitate the combustion of the fuel and to direct the generated flue gas into the heat transfer zone.
The furnace 202 of the present disclosure has more usable volume in a small size. Thus, the grate 206 can accommodate higher quantities of fuel. The smaller size of the furnace 202 results in a cost effective product.
Furthermore, refractory lining facilitates the retention of heat within the furnace 202. The retention of heat within the furnace 202 reduces startup time required for the boiler to start during the start of a next intermittent cycle of operation. Also, the configuration of the plurality of convective pass tubes 210 is such that there is substantially less amount of water hold up within the convective tubes. This further reduces start up delay during the start of a next intermittent cycle of operation.
TECHNICAL ADVANCES AND ECONOMICAL SIGNIFICANCE
The boiler of the present disclosure described herein above has several technical advantages including but not limited to the realization of a boiler having an integral furnace:
- that has an optimal configuration capable of providing higher combustion volume and residence time;
- that does not cause start-up delay during an intermittent operation due to lower water holdup of boiler thereof;
- that can combust various types of solid fuels and utilize various type of combustors; and
- that is cost effective.
The foregoing disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully revealed the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, elements, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:1. A boiler (200) comprising:
a shell (208) having:
a first portion (222) having a cylindrical configuration, said first portion housing a first plurality of tubes (210);
a second arcuate portion (220) extending from said first portion, said second arcuate portion (220) housing a second plurality of tubes (212) such that said first plurality of tubes (210) and said second plurality of tubes (212) are in fluid communication;
a pair of supports (204) configured to support said shell (208), said pair of supports (204) being disposed operatively below said shell (208) in a spaced apart configuration; and
a grate (206) disposed and supported operatively between said pair of supports (204) and operatively below said second arcuate portion (220) such that said pair of supports (204) and said second arcuate portion (220) define an integral furnace (202) for the combustion of fuel such that the flue gases formed due to the combustion of fuels on said grate (206) enter said first plurality of tubes (210) and said second plurality of tubes (212) for use as a heat source for production of steam.
2. The boiler as claimed in claim 1, which includes a reversal chamber (214) disposed adjacent said shell (208) and in fluid communication with said first plurality of tubes (210) and said second plurality of tubes (212) such that the flue gases from said first plurality of tubes (210) enter said reversal chamber (214) and exit said reversal chamber (214) to enter said second plurality of tubes (212).
3. The boiler as claimed in claim 1, which includes a heat recovery unit (218) in fluid communication with said second plurality of tubes (212) and configured to receive the flue gases from said second plurality of tubes (212) and using the remnant heat of the flue gases to pre-heat the feedwater entering said boiler (200).
4. The boiler as claimed in claim 1, wherein said pair of supports (204) are provided with a refractory lining at an operative inner surface thereof to facilitate retention of heat within said integral furnace (202).
5. The boiler as claimed in claim 1, wherein said grate (206) is selected from a group consisting of a stationary grate, an underfeed stroker, a chain grate, and a reciprocating grate.
6. The boiler as claimed in claim 1, which includes a blower (228) disposed operatively below said first portion and configured to supply air to said grate to facilitate the combustion of fuel thereon.