Combustion system with ultralow nox emission and rapid fuel mixing method

Abstract

This relates to a combustion system (10) using rapid mixing fuel gas method with combustion air to obtain intense mixture of air flow with strong rotational components with a plurality of gas jets being discharged for this flow. The assembly of the combustion system (10) includes an external body provided with an air inlet and mounting flanges. The external body (12) is connected to the conical outlet element (18) and further to the combustor with cylindrical shape (20). The combustion system (10) further includes the fuel set comprised by two coaxial tubes (24) and (26) with curved swirl fins (42) and gas injectors (48). This assembly is placed inside the external body (12) along the burner axis with the fins (42) being positioned close to the conical element inlet (18). The combustion system operates using a rapid mixing method, with the fuel gas jets injected and regularly distributed in the combustion air flow with high intensity rotational components.

1 . A COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION comprising an external body with cylindrical shape with the mounting flanges arranged on the inlet and outlet openings; said external body being equipped with an air entry having rectangular or cylindrical or any other appropriate shape to deliver the combustion air to the external body; which includes a plurality of fins distributed on the external face of the external tube, which comprises a plurality of orifices; wherein each fin comprises at least three fuel gas (FG) injectors, which are mounted on the corresponding orifices communicant with the annular space; each injector having a plurality of openings which discharge the fuel gas (FG) in the combustion air flow under the pre-arranged angles; said fuel gas injectors being positioned inside the air passages and supported in the direction of the curvature surface of the fins; the fuel discharge openings being positioned in an aerodynamic cavity with lower pressure due to the curvature of the fins; said discharge openings of the injectors being duly distributed so that the gas jets (GJ) are evenly discharged, from the bottom to the top of the passage, in the air current that flows through the passage between the fins. 
     
     
         2 . The COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION according to  claim 1 , wherein the height of the gas injectors can vary in the direction of the flow, such as, gradually, whereby the first injector three discharge openings while the second injector comprises four openings and the third injector comprises five discharge openings. 
     
     
         3 . The COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION, according to  claim 1 , wherein the number of fuel (FG) discharge openings in each injector can vary wherein the ratio of the discharge area among the injectors remains the same, whereby the taller the injector, the greater the number of discharge openings. 
     
     
         4 . The COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION, according to  claim 1 , wherein said injectors are arranged in a row along the air current movement direction, one after the other, whereby there may be three or less in number. 
     
     
         5 . The COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION according to  claim 1 , wherein distance (L) between the injectors can vary from 1 to 2 of a diameter (D) of an injector. 
     
     
         6 . The COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION, according to  claim 1 , wherein the first injector is shorter in height (H 1 ); the third injector which end presents greater height (H 3 ); the second injector arranged between the first and third injectors having intermediary height (H 2 ). 
     
     
         7 . The COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION according to  claim 1 , wherein the number of openings and diameter (d) can vary depending on the capacity and physical size of the combustion system, wherein the first injector is equipped with three openings, the second with four openings and the third with five openings; all the ports having the same diameter (d), depending on the size and thermal capacity of the burner; the openings being positioned in a row from the upper wall of the injector while being regularly distributed with a distance (X) between the adjacent ones, which is around 2 to 3 of the diameter (d) of each opening; the fuel gas is discharged through the openings evenly covering the distance from the bottom to the upper part of an air passage. 
     
     
         8 . The COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION according to  claim 1 , wherein the discharge openings of the gas fuel jets direct from the injector with height (H 1 ) at angle (α), and capable of being within 0° to 90° to the axis of the combustion system; the fuel gas discharge openings direct the gas jets from the tallest injector (H 3 ) with angle (γ) relative to the burner axis parallel to the tangential line to the external curve of the fin; the fuel gas discharge openings direct the gas jets of the injector with height (H 2 ) with angle (β) relative to the axis of the burner predominantly parallel the axis of the combustion system equal to zero. 
     
     
         9 . The COMBUSTION SYSTEM WITH ULTRALOW NOX EMISSION, according to  claim 1 , wherein the main body of the combustion system is formed by an external body attached by the flange to the conical element which, in turn, is mounted on the combustor which can be manufactured from stainless steel or refractory material in cylindrical shape; the fuel gas being delivered to the fuel gas set provided with coaxial tubes and comprising a channel; the fuel gas (FG) inlet being orthogonally assembled to the external tube; a flange blocks the inlet capable of receiving an oil lance as second fuel; the outlet side being blocked with the plate, which is covered with an insulating layer; the fuel gas set on the discharge side being equipped with a plurality of fins in curved shape, which together with the outer surface of the tube comprise the passages. 
     
     
         10 . A RAPID FUEL MIXING METHOD, comprising a rapid mixing method with elevated excess air to produce ultralow NOx emission which comprises:
 phase 1—supply of combustion air to the external body which flows through the passages of the fins forming an air current with intense rotational components; fuel gas being provided through the annular channel which is formed by two coaxial tubes; the external tube having perforations, and over these perforations gas injectors are installed; each injector having orifices which discharge the gas in the combustion air current;   phase 2—the fuel gas flows through the openings of the injectors and is discharged in the passages of the fins of a turbulator to be evenly distributed around the circumference and within the rotational air flow, and further to mix rapidly and completely thereto;   phase 3—the completely mixed mixture is subsequently inflamed and stabilized in the conical element and next in a combustor; the stabilization mechanism is by means of the recirculation of hot combustion products moving in the opposite direction of the flame from the combustor into the conical element; said hot combustion products will constantly relight the mixture of fuel gas/air originating from the passages of the fins;   phase 4—the nature of the flame stabilization is a reignition aerodynamic effect.   
     
     
         11 . The RAPID FUEL MIXING METHOD, according to  claim 10 , wherein the method further comprises the discharge and mixture of fuel gas with air in a lower pressure zone created along the external curve of the fin. 
     
     
         12 . The RAPID FUEL MIXING METHOD, according to  claim 10 , wherein the gas injectors have different heights (H 1 ), (H 2 ) and (H 3 ) and number of discharge openings arranged so that the fuel gas is gradually discharged from the bottom to the top of the passage between the fins. 
     
     
         13 . The RAPID FUEL MIXING METHOD, according to  claim 12 , wherein each gas injector is surrounded by fresh air currents, without interposition between the gas jets of each injector. 
     
     
         14 . The RAPID FUEL MIXING METHOD, according to  claim 10 , wherein the discharge openings of the gas injectors discharge the gas jets in the air current under specially arranged angles. 
     
     
         15 . The RAPID FUEL MIXING METHOD, according to  claim 14 , wherein the gas jets from the short injector are discharged within 0° to 90 degrees to the combustion system axis, from the average height (H 2 ) injector parallel the axis of the burner the tallest injector (H 3 ) predominantly parallel to the tangential line to the external curve of the fin.