FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(Section 10; rule 13)
ENCLOSED GROUND FLARING SYSTEM FOR FLARING OF RELIEF GASES
Ador Welding Ltd.
An Indian Company
of C/O RD Mate, Equipment Plant,
Chinchwad, Pune-411019
Maharashtra, India
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
The present invention relates to ground flares and more particularly, to an enclosed ground flare system adapted for the efficient combustion of waste/relief gases.
BACKGROUND OF THE INVENTION
Flaring is a high-temperature oxidation process used to burn combustible components, mostly hydrocarbons, of waste/relief gases released from industrial operations. Flare stack is a device used to safely burn industrial waste/relief gases, such as hydrocarbons in an environmentally friendly manner. Normally, two types of flares are well known in the art, namely an elevated flare and a ground flare.
Ground flares are increasingly used to achieve smokeless burning under all flow conditions, and more specifically for noise and radiation free combustion of the waste/relief gases. The ground flares are of two types, namely an open ground flare and an enclosed ground flare. The enclosed flare systems aim to eliminate the light and noise from the flaring of waste/relief gases. These types of flares are extensively used for combustion of waste/relief gases in chemical plants, such as for example hydrocarbon loading terminals, refineries, and the like where low emission of waste/relief gases with efficient combustion is required.
Efforts are seen in the prior art to develop an improved enclosed ground flare systems. For example, US Pat. No. 3703349 to John F. Straitz et al teaches a ground flare for use on the ground with vertical rectangular enclosure. The nozzles have the openings to discharge gas upwardly and outwardly in a conical pattern for admixture with the interior air. Reference may be made to US Pat. Pub. No. 20080081304 to Roger L. Poe et al describes a flare apparatus and methods of flaring flammable waste/relief gases. In these systems, generally, a flare burner is provided that is capable of combusting a high volume of fuel with a relatively

short flame envelope. The burners of the prior art ground flare systems normally have diffusion type fuel jets.
/ However, the apparatuses available in the prior art utilize vertical arrangement of the burner assembly and lack the control system for monitoring flow of the gas. Also these apparatuses have limited working capacities and essentially require high amount of purge gas. Further, these systems are not suitable to work under all atmospheric conditions, such as for example, heavy rain.
Accordingly, what is needed is an enclosed ground flare system that utilizes a burner assembly circumferentially arranged on the enclosure to provide maximum combustion rate. Further, what is needed is an enclosed ground flare system having highest capacity with substantially less amount of purge gas requirements. Also, what is needed is an enclosed ground flare system that facilitates smokeless combustion of the waste/relief gases without need of compressed air assistance during combustion. SUMMARY OF THE INVENTION
An enclosed ground flare system adapted for efficient combustion of flare gases is disclosed. The enclosed ground flare system includes a knock out drum that feeds a flare gas to the enclosure assembly through a flare gas line thereby separating a condensate liquid from the enclsure assembly. The knock out drum subsequently feeds the flare gas to a branch header and a plurality of headers. The enclosure assmebly further includes a first enclosure and a second enclosure having a conical shape, wherein the first enclosure and the second enclosure respectively has a plurality of panels positioned along a circumferential periphery thereof. Each of the panels defines a suction window having a plurality of first type burners positioned at a bottom portion thereof, a plurality of second type burners and a plurality of pilot burners positioned therein. Each of the burners has an air guide with a plurality of air guiding rods adapted for facilitating enhanced flow of a natural draft air through the burners.

The burners receive the flare gases through the headers for mixing with the natural draft air for efficient combustion of the flare gases. Theenclosed ground flare system further includes a staging control mechanism that divides flow rate of the flare gases into a plurality of stages through an ultrasonic flow meter for effective combustion of the flare gases. BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a preferred embodiment of an enclosed ground flare system constructed in accordance with the present invention;
FIG. 1A is a front view of the enclosed ground flare system of FIG. 1;
FIG. 2 is a front cross-sectional view of an enclosure of the ground flare system of FIG. 1;
FIG. 3 is a side perspective view of a burner of the enclosed ground flare system of FIG. 1;
FIG. 4 is a top view of the burner of the FIG. 3;
FIG. 5 is a top view of the enclosure of FIG. 1;
FIG. 6A-6C are side views showing an arrangement of the burner on a header for a first enclosure of the enclosed ground flare system of FIG. 1;
FIG. 6D-6F are side views showing an arrangement of the burner on a header for a second enclosure of the enclosed ground flare system of FIG. 1;
FIG. 7 is a cross-sectional view of the burner of FIG.6 showing flow of a flare gas;
FIG. 8 is a cross-sectional view of the burner of FIG. 6 showing flow of the flare gas; and
FIG. 9 is a block diagram of the enclosed ground flare system of FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION:

Referring to FIGS. 1, 1A and 2, an enclosed ground flare system 10 in accordance with a preferred embodiment of the present invention is shown. The ground flare system 10 includes a knock out drum 12, a staging control system (not shown) and an enclosure assembly 14. The knock out drum 12 is preferably positioned perpendicular to the enclosure assembly 14. The knock out drum 12 facilitates separation of condensate liquid. The staging control system (not shown) includes an ultrasonic flow meter (UFM) (not shown), a PLC panel (not shown), a plurality of headers and remote valves (not shown). UFM is based on the principle of ultrasonic transit time measurement method. It is understood here that UFM is a means to generate signals for staging control valves in this particular embodiment. A flare gas line 16 from knock out drum 12 is provided with upstream and downstream lines. These lines after passing through knock out drum 12 is divided into a branch header 18 adapted to feed the flare gas to the enclosure assembly 14. The branch header 18 has a plurality of sub branches that are further divided into a plurality of headers 20.
The enclosure assembly 14 includes a first enclosure 22 and a second enclosure 24 in this one preferred embodiment. Enclosure assembly 14 includes a plurality of panels 26 arranged in a predefined fashion along a circumferential periphery of the enclosures 22, 24. In this preferred embodiment, first enclosure 22 and second enclosure 24 respectively includes 24 numbers of panels 26 positioned along the circumferential periphery of the enclosures 22 and 24. However, it is understood, that first enclosure 22 and second enclosure 24 may have any number of panels 26 in other alternative embodiments of the enclosed ground flare system 10.
Each of the panels 26 includes a suction window 28 preferably located at a bottom portion of the panel 26. A plurality of burners 30 for example, a diffusion type burner in this one embodiment, is positioned in a predefined fashion inside the suction windows 28. However, it is understood that other types of burners 30 may be utilized in other alternative

embodiments of ground flare system 10. The first enclosure 22 and the second enclosure 24 respectively has a conical shape in this one preferred embodiment such that a bottom diameter of the enclosures 22, 24 is relatively greater than a top diameter. In this one particular embodiment, the bottom diameter of enclosures 22 and 24 is 16.5m. The top diameter of the enclosures 22, 24 is 12.5 m. A height of enclosures 22 and 24 is about 18m. An insulation layer of thickness 50 mm is provided inside the enclosures 22 and 24. The insulation layer protects the enclosures 22, 24 from high temperatures and radiation effects. The first enclosure 22 and the second enclosure 24 respectively has a top portion that is open to atmosphere for exhausts of combustion products.
Referring to FIGS. 3-5, the diffusion type burner 30 of the preferred embodiment of the ground flare system 10 of the present invention is shown. The burner 30 includes a flange 40, a member for buffer gas storage 42, an air guide 44, a support member 46 and a dispenser 48. The dispenser 48 is having a plurality of openings 50 adapted for gas discharge. The flange 40 is connected to the dispenser 48 through the member 42. Air guide 44 includes a plurality of rods/bars/shafts 52 that facilitates enhanced flow of natural air draft to the enclosure.
In this preferred embodiment, the system 10 includes two types of burners, namely a first or Type-I burner and a second or Type-11 burner. The Type-1 and Type-II burners are tangentially projected inside the enclosure up to an optimum distance via suction windows 28 (Refer FIG. 2). Each suction window 28 (Refer FIG. 2) carries three number of Type-II burners and every third window carry one Type-I and three Type-II burners. Burners 30 are preferably positioned on the inner circumference of the enclosure. A pilot burner (not shown) is positioned in each suction window 28 (Refer FIG. 2) to facilitate ignition of main burners 30.

Now referring to FIGS. 6A-6C, an arrangement of plurality of burners 30 positioned on the respective headers 18 (Refer FIG. 1) coming from the knock out drum 12 (Refer FIG. 1) is shown. First enclosure 22 includes preferably eighty burners. In this one preferred embodiment, eight burners are connected to first header 20a, twenty-four burners are connected to second header 20b, twenty-four burners are connected to third header 20c and twenty-four burners are connected to a fourth header 20d. Burners 30 are preferably positioned vertically on 24 numbers of panels 26 at equal degree of peripherals such that 16 numbers of panels 26 includes three burners and remaining eight panels 26 have four burners and one pilot burner 54. Pilot burners 54 are preferably vertically positioned on the top of each burner group. Pilot burner 54 includes a plurality of igniters (not shown) that aids enhanced combustion of the flare gas.
As shown in FIG. 6D-6F, second enclosure 24 preferably includes eighty burners. In this one embodiment, twenty-four burners are connected to fifth header 20e, twenty-four burners are connected to sixth header 20f and remaining twenty-four burners are connected to seventh header 20g.
Referring to FIG. 7-9, in operation, flare gas from the knock out drum 12 circulates to enclosure assembly 14 via branch header 18. Flare gas from branch header 18 further flows to the sub-branches that are divided into plurality of headers 20. Flare gas from the respective sub-headers flows to the respective burners 30 attached to the headers 20. The flare gas after passing through the member 42 gets mixed with the natural draft air that comes into contact with the gas from the air guiding shafts/bars 52. Natural draft air received by the pilot burner 54 gets mixed with the flare gas for enhanced combustion.
Now referring to FIG. 9, in operation, first enclosure 22 has about 50% flow divided into four stages using a staging control mechanism. A first stage 91 is without control and used for minimum flow with purging. In this step, an input signal from an ultrasonic flow

meter 90 (UFM, hereinafter) is analysed and equivalent output signal is generated to activate/deactivate next stages, for example, a second stage 92, a third stage 93 and a fourth stage 94. If a minimum flow rate exceeds beyond highest set point then signal from the UFM activates second stage. In second stage 92, on exceeding minimum flow rate beyond highest set point the signal is generated to activate third stage 93 and on further exceeding minimum flow rate of third stage 93 beyond highest set point due to which fourth stage 94 is activated. For staging control of remote valves micro-processor based programmable logic controller panel (PLC panel, hereinafter) 95 is used. The PLC panel has safety interlocks to ensure smooth operation. Staging control and flow for each stage, number of burners in operation for first enclosure 22 is as depicted in Table 1.
Tablel: (Staging control for first enclosure 22)

Sr.No. Stage No. Flow (MMSCMD) No. of burners Number of pilots in action
1 One 2X10A-7 (*) 8 24
2 One +Two 1.33 20 24
3 One + Two + Three 2.66 44 24
4 One + Two + Three + Four 4 80 24
* For first stage 91 purging is required in case the flow is ess than 2X10-7 MMSCMD (554.89 SM3/Hr).
Second enclosure 24 has about 50% flow divided into three stages. In a first stage 96, an input signal from the UFM is analyzed and equivalent output signal is generated to activate/deactivate next stages, for example, a second stage 97 and a third stage 98. If a minimum flow rate exceeds beyond highest set point then signal from the UFM activates second stage 96. In second stage 96, on exceeding minimum flow rate beyond highest set

point the signal is generated to activate third stage. For staging control of remote valves micro-processor based PLC panel is used. PLC panel have a safety interlocks in to ensure smooth operation. Staging control and flow for each stages 95-97, number of burners in operation for second enclosure 24 is as depicted in Table 2. Table 2: (Staging control for second enclosure 24)

Sr.No. Stage No Flow (MMSCMD) No. of burners Number of
pilots in
action
1 One 5.33 24 24
2 One +Two 6.66 48 24
3 One + Two + Three 8 72 24
Referring now to FIGS. 1-9, in operation, the enclosed ground flare system 10 of the present invention provides invisible flame, low noise and very effective isolation of radiations from external surface of the enclosure. Specially designed openings at bottom of the stack ensure smokeless combustion without air assistance. System 10 of the present invention is designed for very worse atmospheric conditions for example, heavy rain fall conditions. Staging system of the present system 10 has very low purge requirements. Diffusion type burners 30 designed in accordance with the present invention has inbuilt air ingress restriction arrangement without purge flow. The shape of the enclosure of the present system 10 is such that it prevents water ingress to the insulation walls in spite of heavy rain. The system 10 of present invention provides 85-90% effective utilization of the air sucked in the enclosure. The system 10 of the present invention facilitates at least 98% destruction of the flare gas burnt.

The embodiments of the invention shown and discussed herein are merely illustrative of modes of application of the present invention. Reference to details in this discussion is not intended to limit the scope of the claims to these details, or to the figures used to illustrate the invention.
WE CLAIM
1. An enclosed ground flare system adapted for efficient combustion of flare gases, the enclosed ground flare system comprising:
a knock out drum feeding a flare gas to, the enclosure assembly through a flare gas line thereby separating a condensate liquid therefrom, the knock, out drum feeding the flare gas to a branch header and a plurality of headers thereafter;
an enclosure assembly having a first enclosure and a second enclosure having a conical shape, the first enclosure and the second enclosure respectively having a plurality of panels positioned along a circumferential periphery thereof, each of the panels defining a suction window having a plurality of first type burners positioned at a bottom portion thereof, a plurality of second type burners and a plurality of pilot burners positioned therein, each of the burners having an air guide with a plurality of air guiding rods adapted for facilitating enhanced flow of a natural draft air through the burners, the

burners receiving the flare gases through the headers for mixing with the natural draft air for efficient combustion of the flare gases; and
a staging control mechanism dividing flow rate of the flare gases into a plurality of stages through an ultrasonic flow meter for effective combustion of the flare gases.
2. The enclosed ground flare system as claimed in claim 1, wherein the first enclosure and the second enclosure respectively includes 24 panels.
3. The enclosed ground flare system as claimed in claim 1, wherein the first enclosure and the second enclosure respectively has a bottom diameter greater than a top diameter to facilitate the conical shape.
4. The enclosed ground flare system as claimed in claim 3, wherein the top diameter is 12.5m.
5. The enclosed ground flare system as claimed in claim 3, wherein the bottom diameter is 16.5m.
6. The enclosed ground flare system as claimed in claim 1, wherein every suction window includes three second type burners positioned therein.
7. The enclosed ground flare system as claimed in claim 1, wherein every third suction window sequentially includes one first type and three second type burners positioned therein.

8. The enclosed ground flare system as claimed in claim 1, wherein the first type burners, the second type burners and the pilot type burners are tangentially positioned at a predefined distance inside the first and second enclosures.
9. The enclosed ground flare system as claimed in claim 1, wherein the pilot burner facilitates ignition of the first and second type burners.
10. The enclosed ground flare system as claimed in claim 1, wherein the first enclosure includes 80 burners and the second enclosure include 72 burners.
11. The enclosed ground flare system as claimed in claim 1, wherein the staging control mechanism facilitates the second enclosure to have at least about 50% of the inlet flow divided into three stages.
12. The enclosed ground flare system as claimed in claim 1, wherein the staging control mechanism facilitates the first enclosure to have at least about 50% of the inlet flow divided into four stages.
13. The enclosed ground flare system as claimed in claim 1, wherein the staging control mechanism remotely operates through a micro-processor based programmable logic controller panel to ensure smooth switching operation between the plurality of stages of the first and second enclosures.
14. The enclosed ground flare system as claimed in claim 1, wherein the first and second enclosures are having a plurality of openings at the bottom of the enclosure to ensure smokeless combustion without compressed air assistance.

15. The enclosed ground flare system as claimed in claim 1, wherein the burners have an inbuilt air ingress restriction arrangement.
16. The enclosed ground flare system as claimed in claim 1, wherein the conical shape of the first and second enclosures assists in preventing a water ingress and optimizing usage of natural draft air for efficient combustion thereof.
17. The enclosed ground flare system as claimed in claim 1, wherein the first and second enclosures mutually facilitate at least about 85% -90% effective utilization of the air sucked therein.
18. The enclosed ground flare system as claimed in claim 1, wherein the first and second enclosures facilitate at least 98% destruction of the flare gas burnt.