TECHNICAL FIELD

[001] The present subject matter relates to a gasifier and method thereof.

BACKGROUND

[002] Gasifiers are used for producing fuel-gases from bio-mass, waste and other substances. Amongst many substances coal is one of the popular substances used in gasifiers, because coal yields better combustible gases. Fuel- gases are combustible and have a number of applications in everyday life. One of the important conditions for operating a gasifier is it's ability to sustain the gasification reactions and to ensure that the fire within the gasifier does not get extinguished and reactions continuously produce required fuel-gases. Meeting these requirements are generally challenging, as often fire within the gasifier tends to either gets doused, or ends up consuming the base-fuel without generating proper fuel-gases. This results in loss of precious time and base-fuel. Further, some other problems of relating to gasifiers are that they are extremely sensitive to the base-fuel type and quality. For example, a gasifier designed to operate for waste material as base-fuel may not operate for coal or bio-mass base-fuel. Even more so, a gasifier designed to operate for coal with certain moisture content as base-fuel may not function properly with a different moisture content as base-fuel.

[003] Gasifiers generally have different zones, e.g. drying zone in which base-fuel is dried, pyrolysis zone where base-fuel under goes pyrolysis, fire or combustion zone and reduction zone. Each zone operates within a temperature range and certain reactions are expected to take place in each zone. Maintaining the temperature of each zone well within the defined temperature range is important, as outside of the temperature range, the expected reactions may not occur. For example, instead of base-fuel undergoing pyrolysis in pyrolysis zone it may not undergo pyrolysis and may get burned and not provide the desired gases. Ensuring that, each zone is well within desired temperature range is another problem and failure to meet this requirement may result in loss of precious base-fuel or sub-optimal performance of gasifiers.

[004] Further, gasifiers are sensitive to type of base-fuel and each type of base-fuel requires substantially different operating conditions. For example, coal is amongst one of the desired base-fuels; however gasifiers are generally sensitive to type and quality of coal itself. One gasifier that works perfectly for one type of coal may not operate if the coal quality is varied slightly. Similarly, while, coal gasifiers are desirable but they have a number of limitations, e.g.: coal gasifiers not only produce fuel-gases but also generate undesirable byproducts like tar; coal gasifiers inherently require supply gases, such as, hydrogen and oxygen for sustaining the gasification reactions. Generally a stream of super heated steam and mixture of gases are used to supply these gases. While, steam is required for ensuring adequate supply of required gases and sustaining gasification reactions; the same steam causes problems. For example, use of steam loads fuel-gases with tar. Cleaning of tar and separating useful gas from tar is a challenging job and requires skills, energy, resources, sophisticated technology and precious time. In addition, gasification of coal at low temperature is difficult due to process predicaments.

[005] Therefore, it is desirable, to have a gasifier that is relatively cheaper, reduces waste, provides higher efficiency, ease and optimal operation and provides relatively cleaner environment. It is also desirable to develop and design a gasifier that at least reduces or eliminates aforementioned problems associated with the gasifiers and also solve other problems that shall become apparent to a personal in the art, after reading this specification. SUMMARY

[006] It shall become clear to a person, after reading this specification, that the following discussion is intended only for illustration purpose and that the subject matter may be practiced without departing from the spirit of the present subject matter.

[007] The present subject matter provides a gasifier. The gasifier has a plurality operating zones each of the plurality zones has a respective zone size and a location. The plurality of operating zones includes a drying zone, a pyrolysis zone, a fire zone, and a reduction zone. One of the challenges that the gasif iers face is consistent production of fuel-gases without regards to the varying base-fuel quality and its constituents. That is production should not be affected when the type/quality, moisture levels etc in the fuel varies. More so, the gasifier should not die e.g., the fire should not get doused or extinguish with change in quality/type moisture levels, other constituents etc of base-fuel. This is generally because the location of the fire zone of conventional gasifier is generally fixed. Furthermore, moving the fire zone is generally not possible because of the construction of the gasifiers, which generally introduce air from sides of the gasifier and therefore sole attempt during the gasification reaction is to ensure that the fire zone remains below air inlet. Moving the fire zone above or along the air inlet causes problems, such like adversely affecting the fuel-gas production and sustenance of the gasifier. Therefore, the fire zone of conventional gasifier needs to be fixed and hence any alteration in the base-fuel quality results in extinguishing or a non-optimal performance of the gasifier.

[008] The present subject matter provides a substantially automated gasifier that enables dynamic adjustment of the location and size of the operating zones by controlled induction of the base-fuel and/or air from top of the gasifier and controlled extraction of discharge such as tar, char, charcoal, ashes etc from the gasifier. Generally introduction of air into the gasifier from top is challenging and otherwise not possible, as it cause extremely volatile fire zone and losses, however the present subject matter, solves this problem by substantially automatically adjusting amount base-fuel that is introduced into the gasifier to ensure that the fire zone shifts at a location within the gasifier where, the gasifier consistently continues to produce the fuel-gas without getting affected. The present gasifier not only provides an adjustable fire zone according to the base-fuel quality and desired gas generation rate, but also substantially eliminates requirement of introducing steam in the gasifier as, the present gasifier enables use of inherent moisture of the base-fuel. Furthermore, the present gasifier reduces the by product, that is product of tar, char, ashes etc is substantially reduced because, the present gasifier enables cracking of primary tar into the fire zone and further cracking of secondary and tertiary tar in the reduction zone. Furthermore, the gasifier of the present subject matter employs slow pyrolysis of the base-fuel instead of fast pyrolysis, that is the base- fuel undergoes pyrolysis at relatively lower temperature and remains under the pyrolysis zone for relatively longer time, that is the base-fuel has relatively longer residential time in the reactor. This is substantial departure from the conventional gasifiers, which often employ fast pyrolysis. A longer residential time enables cracking of base-fuel into primary and subsequently tertiary derivatives. For example, in case where base-fuel is coal, the coal gets cracked into primary tar during the pyrolysis and subsequently in secondary and tertiary tar, which enables higher amount of fuel-gas generation as well as lower amount of tar (by-products) generation.

[009] According to one aspect, the present subject matter provides a gasifier. The gasifier comprising: a reactor, a feeder, an extractor, and an outlet, wherein each of the feeder, the extractor, and the outlet is coupled to the reactor and the reactor is configured to generate fuel-gas from base-fuel; a sensor unit provided in the reactor; and a controller, wherein the controller is configured to receive: a first signal; a second signal; and a sensor-signal, wherein the first signal being indicative of rate of fuel-gas extraction; the second signal being indicative of physical parameter of base-fuel, and the sensor-signal is received from the sensor unit, and the controller is configured to generate a thermodynamic indicator based on the first signal and the second signal and monitor the sensor-signal and trigger at least one of the feeder, the extractor and the outlet according to the thermodynamic indicator and the sensor-signal.

[0010] According to one embodiment of the present subject matter the extractor is triggered by the controller to extract discharge from the reactor. According to another embodiment, the feeder is triggered by the controller to introduce base-fuel and/or air into the reactor through the feeder. According to yet another embodiment of the reactor is substantially vertical cavernous structure having a top end and a bottom end and feeder being coupled at the top end and the feeder is configured to introduce base-fuel and air into the reactor. According to a further embodiment, the extractor being coupled at the bottom end and the extractor is configured to extract discharge from the reactor. According to an embodiment, the reactor is configured to cause slow- pyrolysis of the base-fuel and thereby causing heat exchange among the base- fuel through the convection. According to yet a further embodiment, the outlet is configured to extract fuel-gas from the reactor. According to another embodiment, the sensor unit is configured to generate the sensor-signal, the sensor-signal being indicative of thermodynamic parameters within the reactor. According to yet another embodiment, the physical parameter is one or more parameters corresponding to the base-fuel defining quality, content and/or size of base-fuel. According to yet a further another embodiment the controller is configured to generate the thermodynamic indicator for the physical parameter of the base-fuel, to enable sustainable gasification reaction within the reactor, and wherein, the thermodynamic indicator is indicative of thermodynamic parameters within the reactor that enable optimal sustainable gasification reaction. According to further embodiment, the base-fuel has moisture level up to 45% and tar produced during the gasification in the reactor is less than ιοο mg per cubic meter at 273 Kelvin temperature and 1 atmospheric pressure and hydrogen content of the fuel-gas after cleaning and cooling the fuel-gas is up to 20 to 25% of volume. According to a further aspect, the gasifier is configured to produce char having carbon content to enable employing of the char as coking coal grade fuel (steel grade I and II) and/or as a reducing agent in smelting iron ore. According to an aspect the gasifier is configured to employ air as sole gasifying agent in gasification reactions and to eliminate requirement of introducing steam into the reactor.

[0011] According to a second aspect of the present subject matter provides, a controller. The controller comprising: a receiver configured to receive a first signal, a second signal and a sensor-signal wherein the first signal being indicative of rate of fuel-gas extraction; the second signal being indicative of physical parameter of base-fuel, and the sensor-signal is received from a sensor unit, and the controller is configured to generate a thermodynamic indicator based on the first signal and the second signal and monitor the sensor- signal and trigger at least one of a feeder, an extractor and an outlet according to the thermodynamic indicator and the sensor-signal to generate fuel-gas from base-fuel, wherein each of the feeder, the extractor, and the outlet is coupled to a reactor of a gasifier. According to an embodiment of the controller, the sensor unit is configured to generate the sensor-signal, the sensor-signal being indicative of thermodynamic parameters within the reactor. According to another embodiment of the controller, the physical parameter is one or more physical parameters corresponding to the base-fuel defining quality, content and/or size of base-fuel.

[0012] According to a third aspect, the present subject matter provides a method for manufacturing a controller. The method comprising: configu ring a receiver to receive, at a controller, a first signal, a second signal and a sensor- signal wherein the first signal being indicative of rate of fuel-gas extraction; the second signal being indicative of physical parameter of base-fuel, and the sensor-signal is received from a sensor unit; enabling the controller to generate a thermodynamic indicator based on the first signal and the second signal and to monitor the sensor-signal; and configuring the controller to trigger at least one of a feeder, an extractor and an outlet based on the thermodynamic indicator and the sensor-signal, each of the feeder, the extractor, and the outlet is coupled to a reactor of a gasifier to generate fuel-gas from base-fuel. According to another embodiment, the method includes configuring the sensor unit is to generate the sensor-signal, the sensor-signal being indicative of thermodynamic parameters within the reactor. According to yet another embodiment, the method includes the physical parameter is one or more physical parameters corresponding to the base-fuel defining quality, content and/or size of base-fuel.

[0013] According to a fourth aspect, the present subject matter provides a method for manufacturing the gasifier. The method comprising: coupling each of a feeder, an extractor, and an outlet to a reactor to generate fuel-gas from base-fuel; providing a sensor unit in the reactor; configuring a controller to receive: a first signal; a second signal; and a sensor-signal, wherein the first signal being indicative of rate of fuel-gas extraction; the second signal being indicative of physical parameter of base-fuel, and the sensor-signal is received from the sensor unit; and enabling the controller to trigger at least one of the feeder, the extractor and the outlet according to a thermodynamic indicator and the sensor-signal, wherein the controller generates the thermodynamic indicator based on the first signal and the second signal and monitors the thermodynamic indicator and the sensor-signal. According to an embodiment, the coupling includes mounting the feeder at a top end of the reactor, wherein the reactor is substantially vertical cavernous structure having the top end. According to yet another embodiment, the coupling includes coupling the extractor at a bottom end of the reactor and wherein the reactor is substantially vertical cavernous structure having the bottom end. According to a further another embodiment, the method includes configuring the feeder to introduce base-fuel and/or air into the reactor upon being triggered by the controller. According to a further embodiment, the method includes configuring the extractor to extract discharge from the reactor upon being triggered by the controller. According to another embodiment, the method includes configuring the sensor unit to generate the sensor-signal, the sensor-signal being indicative of thermodynamic parameters within the reactor.

BRIEF DESCRIPTION OF DRAWINGS

[001 ] The subject matter shall now be described with reference to the accompanying figures, wherein:

[0015] FIG. 1 shows a schematic diagram of a gasifier according to an embodiment of the present subject matter;

[0016] FIG. 2 shows a schematic block diagram controller according to an embodiment of the present subject matter;

[0017] FIG. 3 shows a schematic block diagram of a controller coupled with a gasifier according to an embodiment of the present subject matter;

[0018] FIG. ^ shows a schematic diagram of a coal gasifier with wet discharge according to another embodiment of the present subject matter;

[0019] FIG. 5 shows a schematic block diagram of a method of manufacturing according an embodiment of the present subject matter; and

[0020] FIG. 6 shows a schematic block diagram of a method of manufacturing a controller according an embodiment of the present subject matter. DETAILED DESCRIPTION

[0021] Before the present subject matter is further described in more details, it is to be understood that the subject matter is not limited to the particular embodiments described, and may vary as such. It is also to be understood that the terminology used throughout the preceding and

forthcoming discussion is for the purpose of describing particular embodiments only, and is not intended to be limiting. It must be noted that as used herein, the singular forms "a", "an", and "the" include plural references unless the context clearly expressly dictates otherwise. [0022] FIG. 1 shows a schematic diagram of a gasifier 100 with dry discharge according to an embodiment of the subject matter. The gasifier 100 has a feeder 102, a reactor 104, a vibrator 106, an outlet 108, a conveyer 110, a sensor unit 112 and a controller 114, a feed cone 152, a feed door 162, a motor 116, a extractor assembly 118, a discharge collector 120, a valve assembly 121, a pre-dry zone 122, a dry zone 12 , a torrefaction zone 126, a pyrolysis zonei28, a fire zone 130, and a reduction zone 132 and a hopper (not shown). It shall become clear to a person, after reading this specification that the FIG. 1 is drawn not to the scale and shows only some elements for the purpose of explaining the subject matter. It shall also become clear, after reading this specification, that the gasifier 100 may include some other elements not shown.

[0023] FIG. 2 shows a schematic block diagram of the controller 114 in more details according to an embodiment of the subject matter. The controller 114 includes a feeder control 202, a monitor 20 , an extractor control 206, an outlet control 208, a second signal line 210, a first signal line 218; and a sensor- signal line 21 , a feeder control line 212, and an extractor control line 216.

[002 ] FIG. 3 shows a schematic block diagram of the controller 114 coupled with the gasifier 100 according to an embodiment of the subject matter. [0025] Reference to FIG. 1, FIG. 2 and FIG. 3 is now made collectively to describe the subject matter in more details. The feed cone 152 and the feed door 162 together forms the feeder 102. The feeder 102 is mounted on the reactor 104. The reactor 104 is substantially vertical cavernous structure. The reactor 104 has a top end at which the feeder 102 is mounted. The feeder 102 is configured to introduce base-fuel into the reactor 104. The base-fuel includes, but is not limited to, coal, waste and biomass. The feeder 102 is also configured to introduce air into the reactor 104. According to one aspect, air is introduced from the top of the feeder assembly 102, along with the base-fuel and there is no other air entry in the reactor 104. Furthermore, the subject matter employs air alone as gasification agent that is, it eliminates need of introduction of steam into the reactor 104, which generally acts as gasification agent. In addition, unlike conventional gasifier, the gasifier 100 does not introduce any air from side of the reactor 104 instead the gasifier 100 introduces air from the top of the reactor 104. This is a substantial departure from the conventional gasifiers, which normally supply air from the sides or from bottom of reactors. Using air alone and eliminating need of steam, as reactive or gasification agent during gasification provides an advantage wherein, base-fuel with higher moisture content may be now used without substantially affecting efficiency or the sustenance of gasification reaction or extinguishing the reactor 104.

Furthermore, not only base-fuel such as coal which generally shows low reactivity and often requires steam for increasing its reactivity may also be now used as base-fuel for gasification. The gasifier 100 not only shows increased versatility in terms of its ability to handle different kind of base-fuel, but also the gasifier 100 enables use of inherent moisture of the base-fuel. This is because, when the base-fuel passes through the pre-drying and vapours from moisture of the base-fuel, this moisture when along with the air -which is introduced from the top- is sucked into the reactor 104 and passes through different zones of the reactor 104 may contribute further in enhancing gasifier operation. While, the conventional gasifier require introduction of steam for increasing reactivity of base-fuel into reactor 104, the gasifier 100 may not need steam introduction for increasing reactivity of base-fuel. The moisture of the base-fuel may produce vapours that are used for adjusting reactivity of base-fuel. Thereby providing a versatile gasifier.

[0026] Inside of the reactor 104 is not exposed to the outside

environment as the reactor 104 is under negative pressure. So no gas comes out from the top which may remain open all the time during operation. According to an aspect, the gasifier 100 may have just one door at the top which may be closed during system shutdown. In some embodiments, the feeder 102 may also include a mesh (not shown) to control size of base-fuel entering into the reactor 104. In some other embodiments, the feeder 102 may also include a dispenser (not shown) for collecting rejected base-fuel that are denied entry into the reactor 104 because of unfit size or other reasons. The feed cone 152 is configured to receive base-fuel. The feeder 102 may be configured to be controlled by the feeder control 202. The feeder control 202 is coupled to the feeder 102 through the feeder control line 212. This shall further become clear, after reading later part of this specification, that the feeder control 202, controls the feeder 102 based on a first signal; a second signal; and a sensor-signal and the feeder 102 may be triggered by the controller 114.

[0027] In some embodiments, the hopper (not shown) may be provided with the vibrator io6.The vibrator 106 helps in proper flow of the fuel through the vessel and also help in proper gas and solid mixing to ensure uniform and rich gas production inside the reactor 104. [0028] The reactor 104 is provides with the sensor unit 112. In one embodiment, the sensor unit 112 may include a set of sensors. In some embodiments, the sensor unit 112 is coupled to the monitor 20 through the sensor-signal line 218. In some embodiments, the set of sensors may include one or more thermometers, one or more pressure gauges, one or more humidity gauges and may also include other sensors for sensing gas concentration and type of gases etc. In some embodiment, the set of sensors are provided at different locations within the reactor 104 to sense respective parameter at a given location. The sensor-unit 112 generates a sensor-signal. In some embodiments, the sensor-signal is a convoluted and/or compressed signal that includes information corresponding to each of the sensors of the set of sensors of the sensor-unit 112. In some other embodiment, the sensor-signal includes a set of signals, each of the signals of the set of signals corresponds to a sensor of the set of sensors of the sensor-unit 112. The sensor-signal is provided to the controller 114. The controller 114 may include a receiver. The receiver may be configured to receive the sensor-signal.

[0029] The reactor 104 has a bottom end and an extractor is coupled at the end of the bottom end. In one embodiment, the extractor includes the motor 116, the extractor assembly 118, the discharge collector 120, the valve assembly 121 and the conveyer 110. It shall however become clear, after reading this specification, that the extractor may include elements other than shown in this embodiment. The extractor is configured to remove discharge from the reactor 104. The discharge is generally refuse and/or by-product of the gasifier. The discharge may include, but not limited to, char, tar, charcoal, ashes etc. In some embodiments, the extractor may have a number of door units for ensuring that the inside of the reactor 104 is not exposed to the outside environment. Each of the doors is configured to open only one door at a time, such that the discharge may be removed from the reactor 104 while prohibiting any air to enter into the reactor 104 from the extractor. In some embodiments, the extractor may also include a mesh system (not shown) and vibrator 115. In some other embodiments, the discharge collector 120 collects the discharge from the reduction zone 132. The motor 116 and the extractor assembly 118 may drive the conveyer no to remove the discharge from the reactor 104. The valve assembly 121 of two air sealed valves which remove the discharge with precision. While the bottom valve remains closed, the top valve remains open and discharge continues to accumulate in the chamber between the two valves. When the bottom valve opens, the top valve shuts and discharge comes out from the accumulation chamber. And the cycle continues. In some

embodiments, the extractor 102 may be configured to be controlled by the extractor control 206. In some embodiments, the extractor control 206, generates signals to sequentially open and close the set of doors (not shown). In some other embodiments, the extractor control 206 may generate signals to select and/or adjust mesh size. In some other embodiments, the extractor control 202 may also control vibrator 115 that mixes and shakes the discharge. According to one embodiment, the extractor has a variable extracting capacity to extract discharge from the reactor 104. The extracting capacity is determined based on rate and amount of gas generation, pressure, temperature inside the reactor 104. The extracting capacity may be adjusted by the controller 114 base on thermodynamic conditions inside the gasifier, base-fuel type and fuel-gas generation rate. In some embodiments, the discharged extracted by the extractor is allowed to slide through a grate. From where the discharge is dropped on a slanting chamber, cooled in situ and collected and taken out of the process by an online auger. This shall further become clear, after reading later part of this specification that the extractor control 206, controls the extractor based on the first signal; the second signal; and the sensor-signal and the extractor may be triggered by the controller 114.

[0030] The gasifier 100 is provided with the outlet 108. The outlet 108 coupled is to the reactor 104. The outlet 108 may be further coupled to a generator and/or engine or in general to a load assembly (not shown). The outlet 108 is also coupled with the controller 11 through the second signal line 218. In some embodiments, the controller 114 may receive the first signal from outlet 108. The outlet 108 may monitor rate of fuel-gas passing through the outlet and generate the first signal corresponding to the rate of fuel-gas generation. I n some other embodiment, suction through the outlet 108 at a given rate is caused by the load assembly. A signal that corresponds to the suction rate is the first signal. The hopper harbors the controls that feed the fuel from the top. It is where the pre-drying and torrefaction take place. In some embodiments, the outlet 108 may be provided with a first chamber (not shown), the first chamber is configure to clean the fuel-gas to remove suspended particles and other impurities such as tar etc. The outlet may be provided with a suction unit (not shown) comprising of a pressure blower, wherein the pressure blower is a variable blowing capacity. The blowing capacity is determined based on rate and amount of gas generation, pressure, temperature inside the reactor 104. The blower capacity may be adjusted by the controller 114.

[0031] Operation of the gasifier 100 in conjunction with its elements may be further understood as follows. The gasifier 100 of the subject matter works in a fixed bed regime, where fire zone 130 is shifted depending on the parameter of the coal/fuel/bio-mass used. Shifting of fire zone 130 ensures that the gasification reaction is self-sustaining. Furthermore, shifting of fire zone based on the parameter of the coal/fuel/bio-mass used also enables generation of output fuel gases having relatively higher hydrogen content compared to conventional gasifiers. I n addition, the gasifier also yields other carbon rich fuels such as coking coal grade fuel (steel grad I and II) and can be used as reducing agent in smelting iron ore in blast furnace. It is noticeable, that the subject matter is a gasifier for coal and employs only air as gasifying agent and does not require any additional steam supply for gasification. The air in the gasifier 100 is drawn from feeder 102 which is fixed at the top end of the reactor 10 . The air is drawn along with the fuel. This is a sharp contrast as compared with

conventional updraft gasifiers, which are generally used in for gasification of coal. Further the reactions with coal at a negative pressure of around 350 to 500 mm of water column than atmospheric pressure at temperature of around

900°C to iooo°C using slow pyrolysis at the inter stage reaction mechanism is significantly different as compared with any conventional gasifier. According to an embodiment, when above parameters are employed for practicing the subject matter, the results are highly desirable in terms of low tar generation sometimes concentration is as low as ιοο mg/Nm ³ or lower. According to an aspect, the temperature of the fire zone rarely exceeds i050°C. The shifting fire zone is controlled enables the gasifier 100 to handle wide ranges of base-fuel size and/or higher moisture.

[0032] In one embodiment, suction through the outlet 108 is caused at a given suction rate. The suction rate may either be manually calibrated according to the load assembly, or the load assembly automatically sets the suction rate. A signal corresponding to the suction rate is generated and provided to the controller 114. The signal is the first signal. The receiver at the controller 114 may receive the first signal through the first signal line 218. The first signal being indicative of rate of fuel-gas extraction. Initially, when the gasifier 100 is not yet generating fuel-gas, suction at the outlet 108 may only result in suction of air or whatever gas that may exist in the reactor 104. In another embodiment, the receiver of the controller 11 receives the second signal. The second signal may be received through the second signal line 210. The second signal is indicative of physical parameter of the base-fuel. The physical parameter is one or more parameters corresponding to the base-fuel defining quality, content and/or size of the base-fuel. The second signal may be fed to the controller 104 manually. In some other embodiments, the second signal may be received from a module that monitors parameters corresponding to the base-fuel defining quality, content and/or size of the base-fuel. For example, moisture content in the base-fuel or carbon content in the base-fuel. In some embodiments, the module may also add or remove part of the base-fuel or wet the base-fuel to balance or achieve desired constituents levels in the base-fuel. The controller 11 also receives the sensor-signal at the receiver through the sensor-signal line 214 from the sensor unit 112. The sensor-signal is discussed in detail in previous discussion. The controller 114 based on the first signal, the second signal and the sensor-signal generates a thermodynamic indicator. Further, a feedback of the outlet control 208 corresponding to change in gas suction rate may also be provided. As a result, the thermodynamics of the reactor 104 changes. I n some embodiments, the monitor 20 may have pre determined set of values inserted in its control. Based on the readings taken from inside of the reactor 104, the monitor 20 may send signals to the extractor assembly 118 through the extractor control 206 and the feeder 102 through the feeder control line 212 the feeder control 202 and run the gasifier 100 according to the pre-determined commands set in it. The commands are logic based algorithms devised to run the gasifier 100 with precision in terms of pressure, temperature, gas composition monitoring. The thermodynamic indicator is an indicator that corresponds to the parameter inside the reactor 104 that would generally achieve the fuel-gas generation rate for a given base-fuel parameters defining quality, content and/or size of the base-fuel. The controller 114 monitors the sensor-signal. I n some embodiments, the sensor-signal may be monitored periodically. In some other embodiment, a threshold may be set that would trigger number of action to initiate feeder 102 to introduce base-fuel and/or air into the reactor 104. The threshold may also be set to trigger initiate extractor to extract discharge from the reactor 104 in order to achieve or maintain an environment inside the reactor 104 that corresponds to the thermodynamic indicator. In some embodiments, the controller 114 compares the

thermodynamic indicator and the sensor-signal and triggers the operation of one of the feeder 102, the extractor 110 and the outlet 108 to achieve optimal fuel-gas generation environment inside the reactor 104.

[0033] When the gasifier 100 is fired, the controller 114, as explained the above determines and enables the amount of base-fuel and/or air that may enter the reactor 104. When the base-fuel and the air enter the reactor 104, it passes through different zones of the reactor 104. When the gasifier 100 is fired, the fire zone moves from one location to another within the reactor 104 until it settles at a location which is optimal for the given thermodynamic parameters. These parameters are monitored and maintained within a given range for a given base-fuel quality/type. Moving the fire zone within the reactor 10 to locate it at location that is optimal to handle the base-fuel provides flexibility to the gasifier to handle different types of base-fuel. Further, the gasifier 100 employs slow pyrolysis. Slow pyrolysis insures that a base-fuel has relatively longer residence time in the reactor 104 and further, the heat transfer among the base-fuel occurs by conductions instead of convention. The conventional gasifiers employ fast pyrolysis, in which the heat transfer occurs due convention instead of conduction, which requires higher temperature and loss of energy in addition, the temperature distribution across the zone is not uniform because convection is primarily responsible for heat distribution. Furthermore, longer residence time of base-fuel in pyrolysis zone 128 allows, the heat transfer to occur via conduction and thereby providing a substantially uniform temperature across the pyrolysis zone 128 .Further, controlled removal of discharge through the extractor assist in achieving optimal operation conditions.

[003 ] Generally, the base-fuel comes at the pre dry zone 122, where the moisture of the base-fuel remains with the fuel, temperature of this zone generally may range from 70 ^D C to 122 ^D C. Subsequently the base-fuel enters the dry zone 12 where the moisture of the base-fuel escapes the base-fuel and it gets dried up. Temperature of the dry zone 12 may range from 90 ^D C to 200 ^D C. The base-fuel then enters the torrefaction zone 126, where the cellulose and the hemicelluloses based hydrocarbons begin to disintegrate to smaller

hydrocarbons. The temperature of the torrefaction zone 126 may be generally range from 180 ^D C to 280 ^D C. The torrefied base-fuel than enters the pyrolysis zone 128 and undergoes pyrolysis. Temperature of the pyrolysis zone 128 may range from 280 ^D C to 380 ^D C. At the pyrolysis zone 128 the gases that are generated are largely organic volatiles and primary tar compounds. The output of the pyrolysis zone 128 enters the fire zone 130 this is where the primary tars are converted in secondary and tertiary tars and most of the volatiles are converted into simple organic molecules. The fire zone 130 is configured to provide required energy for pyrolysis process. The pyrolysis process is slow pyrolysis process. The fire zone 130 also provides necessary energy for endothermic reaction taking place in the reduction zone 132 below the fire zone 130. The fire zone 130 operates in a temperature range from 850-1000 degree Celsius The temperature range being sufficient to ensure that a sustained slow pyrolysis which generally requires the temperature from 350 ^D C to 400 ^D C. The temperature range of the fire zone 130 being sufficient to ensure that the reduction reaction zone 132 is sustained. The reduction reaction generally takes place in the temperature range 900 ^D C to 600 ^D C. The fire zone 130 further ensures that the cracking or breaking down of primary tar produced during pyrolysis process and generate exothermic reaction. In the process of breaking down the primary tar into desired products, the fire zone also produces secondary and tertiary tar, the secondary and tertiary tar may be supplied to the reduction zone 132, where the secondary and tertiary tar is further reduced to produce fuel-gas.

[0035] Furthermore, location of the fire zone 130 within the gasifier is determined based on pressure, temperature, fuel-gas generation and moisture content and particle size and shape of the base-fuel. The controller is configured to adjust location of the fire zone based on above mentioned thermodynamic conditions inside the reactor 104 and physical parameters of the base-fuel.

[0036] In one embodiment, the reduction zone 132 is configured to produce fuel-gas and to crack secondary and tertiary tar. This is advantageous as conventional reduction zone only produce fuel-gas but do not participate in cracking of secondary and tertiary tar in char bed. Because of this the subject matter provides low tar production as compared with conventional gasifiers and the hot gas can be directly used in all thermal applications both in hot and cold modes including ultra clean applications like cooking and food industries.

[0037] The pyrolysis, according to one aspect of the subject matter, is a slow pyrolysis process. Slow pyrolysis process provides a number of advantages over the generally used fast pyrolysis in convention gasifiers. These advantages are discussed in the previous discussion. For example, slow pyrolysis along with the other features (such as controlled fire zone location) of the gasifier 100 enables the gasifier to handle variety of base-fuel and optimally generate fuel- gas. The gasifier 100 has shown effective handling of fuel such as coal having moisture contents up to 45% whereas, conventional gasifiers often fail in handling base-fuel having moisture content beyond 20%.

[0038] The gasifier 100 has ability to yield high value carbon rich fuel that comes out as a discharge through the extractor. This discharge may be coking coal grade fuel (Steel Grade I and II) and can be used as a reducing agent in smelting iron ore in a blast furnace.

[0039] FIG. ^ shows a schematic diagram of a gasifier 400 according to another embodiment of the present subject matter. According to this embodiment the gasifier 400 produces a wet discharge. The gasifier 400 is substantially similar to that of the gasifier 100 of FIG. 1, except that the gasifier 400 has a specially designed extractor which consists of char removing grate with breakers water sealed from below. The tub 02 and the extractor of the gasifier 100 is adjusted to handle wet discharge. The option for dry discharge or wet discharge depends on the demand of a customer.

[00 0] FIG. 5 shows a schematic block diagram 500 of a method of manufacturing a controller according an embodiment of the present subject matter. At block 502, a receiver is configured to receive, a first signal, a second signal and a sensor-signal. The controller comprising the receiver. The first signal is indicative of rate of fuel-gas extraction. The second signal being indicative of physical parameter of base-fuel. The sensor-signal is received from a sensor unit. At block 504 the controller is enabled to generate a thermodynamic indicator based on the first signal and the second signal and to monitor the sensor-signal. At block 506 the controller is configured to trigger at least one of a feeder, an extractor and an outlet based on the thermodynamic indicator and the sensor- signal, each of the feeder, the extractor, and the outlet is coupled to a reactor of a gasifier to generate fuel-gas from base-fuel.

[00 1] At block 512, method provides for configuring the sensor unit. The sensor unit is configured to generate the sensor-signal, the sensor-signal being indicative of thermodynamic parameters within the reactor. In one embodiment, at block 521 the controller is configured to receive the physical parameter. The physical parameters are one or more physical parameters corresponding to the base-fuel defining quality, content and/or size of base-fuel.

[00 2] FIG. 6 shows a schematic block diagram 600 of a method of manufacturing a gasifier according an embodiment of the subject matter.

According to an aspect of the method 600, at block 602 each one of a feeder, an extractor, and an outlet are coupled to a reactor to generate fuel-gas from base- fuel. In one embodiment, at block 611, the coupling includes mounting the feeder at a top end of the reactor, wherein the reactor is substantially vertical cavernous structure having the top end. In one embodiment, at block 621, coupling includes coupling the extractor at a bottom end of the reactor and wherein the reactor is substantially vertical cavernous structure having the bottom end. At block 602, the reactor is provided with the sensor unit. At block, 604, a controller is configured to receive: a first signal; a second signal; and a sensor-signal. The first signal is indicative of rate of fuel-gas extraction. The second signal is indicative of physical parameter of base-fuel. The sensor-signal is received from the sensor unit. At block 606 the controller is enabled to trigger at least one of the feeder, the extractor and the outlet according to a

thermodynamic indicator and the sensor-signal. The controller generates the thermodynamic indicator based on the first signal and the second signal and monitors the thermodynamic indicator and the sensor-signal. According to an aspect, the method 600, at block 608 provides for configuring the feeder to introduce base-fuel and/or air into the reactor upon being triggered by the controller. According to a further aspect, the method 600, at block 610 provides, configuring the extractor to extract discharge from the reactor upon being triggered by the controller. According to another aspect, at block 612, the method provides configuring the sensor unit to generate the sensor-signal, the sensor-signal being indicative of thermodynamic parameters within the reactor.

[00 3] While the subject matter may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described herein. Alternate embodiments or modifications may be practiced without departing from the spirit of the subject matter. The drawings shown are schematic drawings and may not be to the scale. While the drawings show some features of the subject matter, some features may be omitted. In some other cases, some features may be emphasized while others are not. Further, the methods disclosed herein may be performed in manner and/or order in which the methods are explained.

Alternatively, the methods may be performed in manner or order different than what is explained without departing from the spirit of the present subject matter. It should be understood that the subject matter is not intended to be limited to the particular forms disclosed. Rather, the subject matter is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the subject matter as described above.