Biomass gasifier system for power generation

Abstract

The various embodiments herein provide an improved biomass based down draft gasifier for producing electrical energy. The gasifier comprises a reactor with double walled construction having an annular space between outer and inner shells. The annular space houses multiple helical guide vanes welded to the inner shell. The reactor is covered with a top cover assembly. An air inlet manifold is provided for directing the controlled air into the reactor through the air inlet nozzles. An automatic start system is provided for controlling the combustion of inlet fuel done with a spark plug. The gasifier comprises a throat which permits the ashes and charcoal of burnt fuel to drop into the bottom of the reactor. The gas separation holes are provided at the bottom of the reactor to separate the product gas from the charcoal. The product gas is taken out from an output pipe.

What is claimed is: 
     
         1 . A down draft gasifier for generating energy comprising:
 a reactor assembly comprising an inner shell, an outer shell, a helical guide vane, and an output pipe, and wherein the reactor is a double walled construction, and wherein the reactor is loaded with a solid fuel, and wherein the reactor is configured to smolder a solid fuel to produce a product gas, wherein the product gas is used to generate a required energy and wherein the helical guide vane is configured to assist a uniform flow of the product gas around an outer peripheral surface of the inner shell, and wherein the output pipe is mounted at extreme top end of the outer shell to eject the product gas yielded from the reactor;   a top cover assembly arranged on the top of the reactor, configured to provide protection to surrounding environment from any hazardous situations created in the reactor;   an air inlet assembly configured for directing a controlled air into a combustion zone of the reactor through a set of air inlet nozzles, wherein the air is used for combustion of the solid fuel to produce the product gas;   an automatic start unit configured to control the combustion of the inlet solid fuel;   a stirrer assembly configured to break the solid fuel into lumps for enabling the stable gas flow, and   a support system configured to sustain a weight of the reactor assembly.   
     
     
         2 . The system according to  claim 1 , wherein the top cover assembly is a spring loaded top cover which automatically opens during an overpressure or an explosion inside the reactor, wherein the top cover assembly is fastened to a top flange of the reactor using a plurality of bolts, wherein the top cover assembly is fastened in a circular manner so as to seal the top of reactor. 
     
     
         3 . The system according to  claim 1 , wherein the air inlet assembly comprises an air inlet manifold provided at the outer surface of the outer shell, wherein the air inlet manifold is configured to supply the air required for combustion of the fuel inside the reactor through a plurality of air inlet nozzles, wherein the plurality of air inlet nozzles are configured to control a quantum of air into the reactor chamber and facilitate a quick replacement in case of corrosion. 
     
     
         4 . The system according to  claim 1 , wherein the air inlet nozzle is adjustable to penetrate inside the reactor by a required distance before an initiation of the reactor, and wherein the air inlet nozzle is inserted into an outer pipe, and wherein the outer pipe is welded with the inner shell and housed inside a gland. 
     
     
         5 . The system according to  claim 1 , wherein the gland allows a free thermal expansion of the air inlet nozzle and avoids a formation of crack on the output pipe due to stress, heat and a differential growth between the inner shell and the outer shell of the reactor. 
     
     
         6 . The system according to  claim 1 , further comprises an angular space between the outer shell and the inner shell of the reactor, wherein the angular space houses the helical guide vane, wherein the helical guide vane is welded to the inner shell of the reactor. 
     
     
         7 . The system according to  claim 1 , wherein the helical guide vane is in arranged in a form of a multi strand thread to guide the product gas to flow in a helical pattern around the inner shell, wherein the helical guide vane increases a residence time of the product gas inside the annular space and causes a heat transfer from the product gas to the surroundings inner shell. 
     
     
         8 . The system according to  claim 1 , further provides a gap of predetermined size between the inner surface of the outer shell and the helical guide vanes, wherein the gap is configured to freely drop down to ash and other solid condensable contaminants to the bottom of the reactor. 
     
     
         9 . The system according to  claim 1 , wherein the automatic start system comprises a Liquefied Petroleum Gas (LPG) fuel line connected to a burner assembly, wherein the LPG is ignited by a built-in spark plug. 
     
     
         10 . The system according to  claim 1 , further comprises a digital control system such as a Programmable Logic Circuits (PLC) for controlling the inlet of LPG and ignition of the spark plug, wherein a control valve is provided to operate a start and stop of combustion process, wherein the control valve is commanded by the digital control system. 
     
     
         11 . The system according to  claim 1 , further comprises a suction blower configured to apply suction at the outer pipe, wherein the suction draws the air from the burner and preheats the air to a predetermined temperature. 
     
     
         12 . The system according to  claim 1 , further comprises a lifting bracket configured to lift and place the gasifier from one location to another location, wherein the lifting bracket is welded to the outer surface of the outer shell. 
     
     
         13 . The system according to  claim 1 , further comprises a hearth provided to support the fuel under combustion and permits a pile of glowing charcoal underneath, wherein the charcoal filters the product gas by breaking down the tar into combustible compounds. 
     
     
         14 . The system according to  claim 1 , further comprises a plurality of radial gas separation holes provided in the wall of the inner shell of the reactor, wherein the holes are configured to separate the product gas from the charcoal, wherein the holes block the charcoal and permit only the product gas to exit from the inner shell to the annular space. 
     
     
         15 . The system according to  claim 1 , wherein the stirrer assembly comprises a stirrer configured to stir the glowing charcoal bed so as to prevent blockages leading obstruction of gas flow, wherein the stirrer is driven by a gear box connected to a motor, wherein the stirrer is rotated by the motor, wherein the stirrer shaft passes through a plurality of glands and enters the bottom of the reactor. 
     
     
         16 . The system according to  claim 1 , further comprises an ash removal funnel placed in the annular space between the inner shell and the outer shell, wherein the ash removal funnel is mounted on an ash removal flange, wherein the ash removal funnel collects the ash dropped to the bottom of the reactor and the collected ash is taken out by the ash removal flange. 
     
     
         17 . The system according to  claim 1 , wherein the support system comprises a plurality of support brackets, wherein the support brackets are sustained by a plurality of stands configured to support the reactor system. 
     
     
         18 . The system according to  claim 1 , further comprises a gas blower attached to the reactor which enhances a start performance and transient response to the load changes, wherein a cyclonic separator is configured to enhance the purity of gas by reducing contamination load on water scrubber and preventing the clogging of water scrubber. 
     
     
         19 . The system according to  claim 1 , further comprises an infrared laser beam configured to detect and indicate the level of fuel consumption inside the reactor. 
     
     
         20 . The system according to  claim 1 , comprises a safety unit configured to automatically shutting down the reactor for a variety of out-of-limit operating parameters, wherein the parameters include a high reactor pressure, a high reactor temperature, a high water temperature, a low water level, a water pump failure, a low frequency, a high frequency, a gas leakage.