Title of Invention

"AN IMPROVED HIGH VELOCITY BURNER"

Abstract

An improved high velocity burner characterised in that the burner comprises; (a) air tubel having an inlet lA,(b) gas tube 2, enclosed co-axially by air tube 1, and provided at the outlet end thereof with one single-hole nozzle 3 for reducing pulsation in the flow of fuel gas there through and one multiple-hole nozzle 4 for allowing discharges of fuel gas there from, (c) first combustion tube(6) having a multiple hole nozzle 5 at the input end, a pilot burner 7 for igniting the fuel gas and a peep hole 8 for observing the state of the flame therein, and at the output end thereof a number of stabilising holes 6A in the wall thereof, and (d) second combustion tube 9 having a tapered exit nozzle 11B and a straight nozzle 11 A, a number of leakage holes 9A and cooling holes 9B in the wall thereof for lowering temperature of the flame therein, an annular gap 10A left between the adjacent ends of the first and the second combustion tubes and an annular ring 10 fitted around the gap with passage left around the outside surface of the second combustion tube.

Full Text

The present invention relates to an improved high velocity burner. The existing high velocity burner has certain drawbacks, such as, (a) both the combustion quarl and exit nozzle being made of refractory, the service life of the burner is relatively short, (b) because of the uncontrolled supply of primary and secondary excess oombustion air, the stability of the flame is poor and the temperature of the flame is low i.e. below 200°C and the burner often extinguishes during the course of its application and (c) in the absence of suitable means for regulating the flow of combustion air and fuel gas i.e. coke oven gas (COG), the temperature of the flame produced can not be varied as required for drying/heating of the refractory linings of blast furnaces and coke oven batteries. The invented high velocity burner, which is operable from coke oven gas supplied at a pressure of 500 - 1500 mm WG and flow rate of 500 lfor/hr maximum, and combustion air supplied at a pressure of 500 - 900 mm WG, is of all-metallic construction, the preferred metal being stainless steel (AlSIs St 310 grade). It consists basically of an outer tube called air tube for supplying combustion air, fitted at the input end of which is an air supply through which combustion air ia blown into the burner at a controlled rate by means of a blower. Inside the air tube, three different tubes are disposed along the length of the burner co-axlally with the air tube of which, the tube provided at the input end of the burner is called 'gas tube', the tube provided adjacent the outlet end of the gas tube is called 'first combustion tube' and the tube provided adjacent the outlet end of the first combustion tube is called the 'second combustion tube'. At the inlet end of the gas tube fuel gas is supplied from a COG line at a controlled rate. At the outlet end of the gas tube two separate nozzles are provided along the length of the gas tube, one following the other, of which the preceding one is a single-hole nozzle for reducing the pulsation in the gas flow and the following one is a multiple-hole nozzle for supplying the gas, which is fitted at the input end of the first combustion tube where another multiple-hole nozzle is provided to allow the combustion air from the airtube to enter into the first combustion tube, a pilot burner is fitted to ignite the burner and a peep-hole is provided for observing the state of the flame inside the first combustion tube. At the outlet end Of the first combustion tube a number of holes, called 'stabilising holes' are made to allow the entry of additional combustion air from the air tube into the first combustion combustton of gas tube for complete and producing a stabilised flame. The input end of the second combustion tube is disposed adjacent the outlet end of the first combustion tube leaving a small gap called 'thermal gap' to allow thermal expansion of the metallic first and second combustion tubes when these are heated. For aligning the position of the said two combustion tubes with respect to the burner axis,, an annular ring, called 'thermal ring' is fitted around the thermal gap leaving a small annular gap around the outside surface of the second combustion tube, through which additional combustion air is allowed to enter into second combustion tube to bring down the temperature of the flame. In addition, more holes, called 'leakage holes' and 'cooling holes' of different sizes are made in the wall of the second combustion tube to allow the entry of excess air for bringing down the temperature of the flame to the required level. The products of combustion are allowed to discharge through a metallic exit nozzle provided at the output end of the second combustion tube, which is fixed to the outlet end of the air tube. The invention is described fully and particularly with reference to the accompanying drawings in which - Figure 1 is a longitudinal section of the existing high velocity burner; Figure 2 is a longitudinal section of the invented high velocity burner. Referring to Fig. 1, the existing high velocity burner comprises an air tube 1 surrounding a tube 2 and a refractory quarl 11. Primary combustion air is blown into the air tube through the inlet 1A and secondary air is blown into the refractory quarl through the inlet 1B in excess of the stoichiometric requirement for combustion of fuel gas (COG), supplied into the refractory quarl through the inlet 2A, because of which the flame of the burner is unstable, extinguishes often and can not attain a temperature about 200°C. Moreover the existing high velocity burner being not provided with suitable means for controlling the temperature of the flame is not applicable for drying/heating of refractory linings of blast furnaces. The inlet end 2B of tube 2 is fixed to the inlet end 1C of the air tube 1. Referring to Fig. 2 the in-vented high velocity burner comprises an air tube 1, a gas tube 2 having a single-hole gas nozzle 3 for reducing the pulsation in the flow of the fuel gas and a multiple-hole gas nozzle 4 at the outlet end thereof, a first combustion tube 6, the input end of which is attached to the multiple-hole gas nozzle 4, and is provided with a multiple-hole air nozzle 5 having holes 5A for supplying combustion air, a pilot burner 7 for igniting the fuel gas and a peep hole 8 for observing the state of the flame inside the first combustion tubes. The number of holes in the multiple-hole gas nozzle 4 is 13 to 20 and that in multiple-hole air nozzle 5 is 30 to 40. The pilot burner is provided with an electrical ignition system, sueh as an automobile spark plug, and is supplied with fuel gas (00G) from a separate line, but with combustion air through a hole 7A from the air tube 1 into which combustion air is blown at a controlled rate through the inlet 1A. A number of stabilising holes 6A, preferably 6 to 10, are made in the wall of the first combustion tube near its outlet end to allow the entry of additional combustion air from the air tube into the first combustion tube for complete eombustion of the fuel gas supplied therein and attaining ftability . of the flame produced. The input end of the second combustion tube 9 is disposed adjacent the outlet end of the first combustion tube leaving a small thermal gas 10A of 2 to 4 mm and an annular thermal ring 10 is fitted around the thermal gap 10A, leaving an annular gap of 2-4 mm around the outside surface of the second combustion tube. Leakage holes 9A and cooling holes 9B, each numbering 5 to 10 are provided in the wall of the second combustion tube in different rows for lowering the temperature of the flame therein. The nozzle fixed to the outlet end of the second combustion tube comprises a tapering part 11B and a straight part 11A through which the products of combustion are allowed to discharge. The nozzle part 11A is fixed to the outlet end 1B of the air tube. The inlet end 2B of gas tube 2 is fixed to the inlet end 1C of the air tube 1. The temperature of the combustion products at the input and output ends of the first combustion tube 6, at the input and output ends of the second combustion tube 9, and at the tapering part and outlet end of the nozzle 11A is indicated respectively by T1, T2, T3, T4 and T5. Field trials have been conducted on the invented high velocity burner in a steel plant using varying pressure and flow rate of the fuel gas and combustion air into the burner, and the temperatures of the combustion products T1, T2, T3, Ti and T5 at different parts of the burner (shown in Fig. 2) together with the discharge velocity of combustion products and percentage of excess air supply have been noted. The results of observations are presented in Table 1. It is noted from Table 1 that the discharge velocity of the products of combustion varies from 58 m/sec to 170 m/sec, and the temperature (T5) of the products of combustion discharged from the exit To 855°C nozzle 11A varies from 132 ºC The excess air supplied to the burner varies from 263 to 2336% of the stoichometric requirement for combustion of the fuel gas supplied. TABIE - 1 Results of the field trial on Inverted High Velocity Burner Calcula- Excess combustion products (Table Removed) We Claim :- 1. An improved high velocity burner which is operable from coke oven gas supplied at a pressure of 500-1500 mm WG and flow rate of 500 Nar/hr maximum, and combustion air supplied at a pressure of 500-900 mm WG, of an extended service life, capable of producing a stable flame of adjustable temperature in the range of 150 to 800°C and suitable for drying/heating the refractory linings of blast furnaces and coke oven batteries, characterised in that the burner comprises of the following components, arranged to function in an inter-dependent manner: (a) air tube 1 having an inlet 1A for blowing combustion air at the required rate thereinto, (b) gas tube 2, enclosed co-axially by air tube 1, and provided at the outlet end thereof with one single-hole nozzle 3 for reducing pulsation in the flow of fuel gas therethrough and one multiple-hole nozzle 4 for allowing discharge of fuel gas therefrom, (c) first combustion tube (6) having a multiple-hole nozzle 5 at the input end thereof for allowing entry of combustion air thereinto from air tube 1, a pilot burner 7 for igniting the fuel gas and a peep hole 8 for observing the state of the flame therein, and at the output end thereof a number of stabilising holes 6A in the wall thereof for allowing entry of additional combustion air therein from air tube 1 for attaining stability of the flame produced, and (d) second combustion tube 9 having a tapered exit nozzle 11B and a straight nozzle 11A, a number of leakage holes 9A and cooling holes 9B in the wall thereof for lowering temperature of the flame therein, an annular gap 10A left between the adjacent ends of the first and the second combustion tubes for allowing thermal expansion thereof and an annular ring 10 fitted around the gap with passages left around the outside surface of the second combustion tube for allowing entry of combustion air thereinto and alignment of tha first and second combustion tubes, said components (a) to (d) being made of a isetal like ctainlea steel of AlSI:St310 grade. 2. The burner as claimed in claim 1, wherein the multiple-hole nozzle 4 is provided with 13 to 20 holes, 3. The burner as claimed in claim 1, wherein the multiple-hole nozzle 5 is provided with 30 to 40 holes. 4. The burner as claimed in claim 1, wherein the pilot burner 7 is provided with an automobile spark plug as an electrical ignition system. 5. The burner as claimed in claim 4, wherein the pilot burner is provided with a hole 7A for supplying combustion air therein from the air tube. 6. The burner as claimed in claim 1, wherein the number of stabilising holes 6A in the first combustion tube is 6 to 10. ?. The burner as claimed in claim 1, wherein both the thermal gap 10A and annular gap between the annular ring 10 and outer surface of the second combustion tube is 2, -to 4 mm 8- The burner as claimed in claim 1, wherein the number of leakage holes 9A and cooling holes 9B provided in the wall of the second combustion tube is 5 to 10 each.

Documents:

671-del-1997-abstract.pdf

671-del-1997-claims.pdf

671-del-1997-correspondence-others.pdf

671-del-1997-correspondence-po.pdf

671-del-1997-description (complete).pdf

671-del-1997-drawings.pdf

671-del-1997-form-1.pdf

671-del-1997-form-19.pdf

671-del-1997-form-2.pdf

671-del-1997-gpa.pdf