US2648376A - Flare stack lighter - Google Patents

Description

L. w, scHRADER 2,648,376

FLARE STACK LIGHTER Filed March 6, 1948 Aug. ll, 1953 MM N FLARE TAcL INSULATEID ELECTRQDE.

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FLARE sfrAcK LIGHTER Leo W. Schrader, Eliza Standard Oil Develop ration of Delaware beth, N. J., assigner to ment Company, a corpo- Application March 6, 1948, Serial No. 13,4 17

2 Claims. l

This invention relates to improvements in flare stack lighters.

In refining petroleum oil there are formed vari: ous gases which due to low fuel value or to the presence of various sulfur compounds are of no practical value and are at times disposed of by. burning stacks. The stacks are of suitable height. in order that the flares will not be a fire hazard.,v Up to the present, the flares were ignited by means. of jet pipes and a slotted tube type of a lighter. In order to propagate llame to the top of the flare. stack it has been found necessary at times to operate the lighter for long periods of time. This resulted in the evolution of 'large quantities of heat which badly distort the lighter equipment;A ln some cases due to high winds it has not been possible at times to light the flare even after prolonged operation of the lighting device. Another difficulty encountered was in obtaining sufficient ii'ow in the upper jets o f the lighter due to poor gas distribution. rlhis resulted in a large flame enveloping the lower portion of the lighter with very little name in the upper lengths. Another difliculty encountered was the clogging in the upper jet pipes due to corrosion.

it is an object of this invention to provide a lighting device that will light the flare at the top of the stack without interference from high winds and without any unnecessary heating effect in the lighter equipment at the lower portion of said equipment by means of a rising llame within a lighter pipe wherein combustion is propagated upwards in a combustible but not explosive mixture of air and gas ignited at the ground level by suitable means. This and other objects `of the invention will be understood on reading the following description where with reference to the accompanying drawings:

Fig. 1 discloses one type of a lighter, and

Fig. 2 a modication of the first type of lighter.

Referring to Fig. 1, numeral I shows a pipe of 2 inches in diameter of the desired length which may be 30 or more feet high depending upon the height of the are stacks. Into this pipe at the lower end is fitted a Meeker laboratory burner injector 2 into which is passed a hydrocarbon gas such as ethane, propane or pentane or other combustible volatile gas. An opening 4 for the admission of air or oxygen is also provided. A suitable diameter for the needle valve orice through which hydrocarbon gas is passed into the upper part of the Meeker burner 2 and into pipe I may be of about .052 inch. The diameter of the Venturi throat is about .625 inch. Into this pipe at about 3 ft. above the lower end of the pipe is fitted a spark plug 5.. This spark plug consists of a single insulated electrode which` projects into the pipe through a hydraulic coupling welded to the pipe and forms a spark gap between the electrode point and the interior surface oi the pipe wall. A high voltage current is supplied to the electrode, and the pipe Wall serves as the ground connection. The high voltage current may be sup.- plied by a scintilla magneto of the type cornmonly installed on compressor engines.

A screen Ev is installed at the point of the at tachment of the Meeker burner to pipe I in order to prevent flash back of the eas in the tube to the burner 2. v

The magnetol drive shaft may be. rOtated by hand to obtain the desired electrode discharge between the electrode and the internal surface o f the pipe. An inlet gas pressure of 35 pounds per square inch gauge Was used to obtain a gas flow of 3 cubic feet per minute, while inspirated air flowed ata rate of about 27 'cubic `feet per minute. This gave an air gas ratio ofA 9,11 by Volume, and the velocityV of the air gasmixture in the tube pipe was calculated to be approximately 1375 feet per minute. Although after the gas was allowed to flow through lthe pipe and the air gas mixture ignited by meansV of the electrode, the llame velocity was found to be about 25.60 feet per minute. v

Referring to Figure 2, a main' flare stack I5 is shown with an, ieniter pipe I`I attached tothe flare stack wall by flanges not shown either inside or outside of the stack. A pipe having a diameter of 2 inches was found to be suitable although other pipes of smaller or greater diameter may be used. Into this pi'pe'is passed a hydrocarbon gas such as ethane, propane or other combustible volatile gas by means of pipe l2 through valve I2@ and air by means of pipe i3 through valve Ita and thence through line it by way of valve Ilia. Where propane was used, it was fed at a pressure of 20 pounds per square inch gauge through an orifice approximately .50 inch in diameter and air at 20 pounds per square inch gauge was fed through an orice approximately .158 inch in diameter. This mixture owed at a rate of 300 cubic feet per hour and was fed into the igniter pipe I I. A spark plug I4 at about 3 it. above the opening through which the Iair and gas are introduced is iitted into the igniter pipe and is provided with contacts for passing an electric current into the said electrode. Before turning on the electric current the mixture of gas and air was rst turned on and the pipe was purged for about 20 seconds Where a 40 ft. lighter pipe was 3 used and then the current was turned on and the iiame passed to the top of the lighter tube and ignited any gas in the main flare stack I9.

In addition to the orifices, a visual mixture control can be used wherein the air and gas mixture is allowed to burn in a small pilot I5 ahead of igniter riser II and the mixture controlled by the iiame characteristic. The pilot I5 is provided with a valve I5a and communicates with the conduit line I6 connecting with the pipes I2 and I3 to supply a combustible gas mixture to the igniter pipe II. The valve Isa is provided in the line I6 intermediate the pilot I5 and the pipe I I. In use, valve Ilia is closed, valve I5a is opened, and the valves in the gas and air lines I2 and I3 are opened to permit a mixture of gas and air to iiow to the pilot. An operator can then attempt to light the pilot using a match, for example. On the rst attempt it may be found that the mixture will not ignite o1 alternatively that the mixture is explosive. In the latter case, combustion will occur as one or more sharp detonations. In either event, the valves in the air and gas lines are adjusted until a combustible mixture is obtained which provides a clean persistent flame. The height or this iiame may then be adjusted also to provide a suitable predetermined flow velocity to avoid flashback when the combustible mixture is supplied to the ignition tube. The pilot can be turned off after mixture adjustment and the flare ignited as before. Any volatile combustible gas can be used for ignition purposes.

The following is claimed.

1. In combination with a iare stack for burning waste combustible gaseous compounds, said stack having an outlet a considerable distance above the ground, an ignition means for said compounds, comprising a separate ignition tube of smaller diameter than the stack and coextensive therewith, a discharge end on said tube directed toward and over said stack, conduit means for supplying to said tube a proportioned mixture of an oxygen-containing gas and a combustible gaseous material, including separate conduits for each of said components of the mixture and flow control means therein, igniter means internally of said tube to ignite said gaseous mixture, and a pilot burner element supplied with said mixture from conduit means supplying said tube, separately ignitable to provide for visual inspection of the flame characteristics of said mixture when ignited, said control means being adjustable to permit the ame height at said pilot burner element to be varied to indicate when a pre-determined critical velocity for name propagation has been reached in said ignition tube,

whereby the said proportioned mixture when supplied to said ignition tube avoids introduction of an explosive mixture therein and prevents iiash back in said tube.

2. In combination with a flare stack for burning waste combustible gaseous compounds, said stack having an outlet at a considerable distance above the ground, a means for igniting said compounds at the stack outlet, comprising a separate ignition tube of smaller diameter than the stack and co-extensive therewith a discharge end on said tube directed toward and over said stack, supply conduit means for introducing a proportioned mixture of an oxygen containing gas and a combustible gaseous material to said tube, including separate inlet conduits communicating with said supply conduit means for each of said components of the mixture and iiow control means therein, igniter means internally of said tube to ignite said gaseous mixture, a pilot burner element communicating with said supply conduit means intermediate the tube and said inlet conduits, and control means disposed in said supply conduit means intermediate the pilot burner and the tube, whereby the mixture as supplied to said conduit means may be diverted to said pilot burner element and separately ignited to provide for visual inspection of the flame characteristics of said mixture, said control means being adjustable to permit the iiame height at said pilot burner element to be varied to indicate when a pre-determined critical velocity for iiame propagation has been reached in said ignition tube, whereby the said proportioned mixture when supplied to said ignition tube avoids introduction of an explosive mixture therein and prevents flash back in said tube.

LEO W. SCHRADER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 791,002 Busey May 30, 1905 935,444 Wolff Sept. 28, 1909 1,415,123 Schulz May 9, 1922 1,566,718 Wolff Dec. 22, 1925 1,827,505 Bluhm Oct. 13, 1931 2,118,741 Smith et al May 24, 1938 2,460,016 Kuhn Jan. 25, 1949 2,480,230 Elster Aug. 30, 1949 2,537,091 Rodman et al. Jan. 9, 1951 FOREIGN PATENTS Number Country Date 349,509 Great Britain May 26, 1931

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