BACKGROUND TECHNICAL FIELD

[0001] The present disclosure generally relates to processing of well fluids for disposal, and more particularly to a clean burner system and method with air charging by gas-turbine engine for burning of well fluids for disposal.

DISCUSSION OF BACKGROUND ART

[0002] At present, well tests produce significant amounts of waste fluid which must be disposed of. Such waste fluid includes a mixture of oil, hydrocarbon gas, and water, and may also include fine particles, toxic gasses such as hydrogen sulfide, as well as additives used for drilling mud, and clean-up fluids. The basic method of processing such fluid for disposal is to separate the water component out of the liquid, and then to separately dispose of the hydrocarbon gas and oil components. On offshore drilling platforms, there is often insufficient infrastructure to process and deliver the oil and hydrocarbon components of the waste liquid for further use. Consequently, the separated oil and hydrocarbon gas components of the waste liquid are often disposed of by combustion. However, because the separated oil and gas may still contain a significant component of water, fine particles, non-flammable chemical additives and toxic gas components, the burning of such separated oil and gas is difficult, and may be accompanied by high emissions of hazardous chemical substances, high noise, and high amounts of heat, all of which have a negative influence on the environment and working conditions for personnel. Thus, the level of environmental pollution is directly related to the effectiveness and completeness of the burning processes used for the disposal of the separated oil and gas.

SUMMARY OF THE DISCLOSURE

[0003] The above and other needs and problems are addressed by the exemplary embodiments, which provide a burner system and method for efficient burning of waste hydrocarbons (e.g., dry gas, wet or retrograde gas, oil-water fluids, etc.) produced during well testing, and wherein efficient and clean burning is achieved by employing forced air charging. The novel system provides an intensive air supply, with preliminary mixing thereof with gaseous or atomized waste hydrocarbons, ejection of such fuel-rich mixture into the atmosphere through a nozzle, and combustion thereof in open-air flame. The air intake is ensured by an airscrew driven by a gas-turbine engine, wherein the engine can operate on the best part of fuel produced during separation of the well effluent during well testing. Advantageously, the system is fed and driven by well fluent (e.g., waste fuel), in most cases. The preliminary mixing of the air with waste fuel provides a flame of better quality (e.g., with low smoke and low heat radiation). Advantageously, the novel system combines the engine, air supply screw, and combustor, as a single unit installed on a boom or on a platform, wherein the gas-turbine aggregate can be an off-the-shelf system produced by the aviation industry. In addition, the employed aircraft engine (e.g., a Russian turbo-prop engine of Russian light-weight aeroplane AN-24, which has power about 2000 h.p. and weight about 600 kg, a Russian turbo-shaft engine TV2 117TG of the popular Russian helicopter Mi-8, which has power about 1000 h.p. and weight about 300 kg, etc.) has sufficient power to create an intensive air blast employed for clean burning of essentially dirty fuel.

[0004] Accordingly, in exemplary aspect of the present disclosure there is provided a system and method for clean combustion of waste hydrocarbon fluids, including gaseous, liquid, or gas-liquid flows, produced during well testing operations, and including a fuel inlet that receives the waste hydrocarbon fluids and stock hydrocarbon fuel; a fuel-dispensing unit coupled to the fuel inlet, and a gas-turbine engine coupled to the fuel-dispensing unit and driven by one or both of the stock hydrocarbon fuel and the waste hydrocarbon fluids. An airscrew on a shaft of the gas-turbine engine drives air into a premix chamber. A set of nozzles in the premix chamber is coupled to the fuel dispensing unit for dispersion of the waste hydrocarbon fluids into the forced air generated by the airscrew toward a pilot light mounted at the downstream end of the chamber. A combustion nozzle coupled to the downstream end of the premix chamber shapes and directs the resulting flame. A control unit is connected to the dispensing unit, regulators in the gas-turbine engine, and feedback sensors for controlling the system. [0005] Still other aspects, features, and advantages of the present disclosure are readily apparent from the entire description thereof, including the figures, which illustrates a number of exemplary embodiments and implementations. The present disclosure is also capable of other and different embodiments, and its several details can be modified in various respects, all without departing from the spirit and scope of the present disclosure. Accordingly, the drawings and descriptions are to be regarded as illustrative in nature, and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The embodiments of the present disclosure are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

[0007] FIG. 1 illustrates an exemplary gas-turbine engine clean burner system with air charging;

[0008] FIG. 2 illustrates another exemplary gas-turbine engine clean burner system with air charging;

[0009] FIG. 3 illustrates an exemplary turbo-shaft engine clean burner system with air charging;

[0010] FIG. 4 illustrates an exemplary clean burner system with air charging and having a premix chamber with air flaps;

[0011] FIG. 5 illustrates an exemplary clean burner system with air charging and having a multi-tube premix chamber and nozzle; and

DETAILED DESCRIPTION

[0012] The present disclosure includes recognition that with well testing operations there is a challenging task of disposal of the fluid produced during such testing operations. This fluid may contain oil, gas, water, fine particles, additives for drilling mud or clean-up fluids, etc. Often, an offshore platform during the exploration stage lacks sufficient pipeline infrastructures to process and deliver waste hydrocarbons, and the like, for further use. Advantageously, the exemplary embodiments provide a simple and efficient system and method for hydrocarbon disposal via on-site burning in environmentally-efficient manner.

[0013] The present disclosure further includes recognition that the duration of hydrocarbons during on-site combustion is from several hours to several days, wherein the problem of clean burning on offshore platforms is different from the problem of waste gas combustion at refineries. In addition, during oil and gas well testing, the composition of waste fuel may vary significantly, and which is especially critical when the water content (e.g., water cut) is too high for efficient (e.g., without smoke and fallout) burning. Further, water and gas slugs in pipe-lines may occur in the background of an oil-dominant flow. Moreover, the flow rate of well effluent is inherently unstable, because of transient processes during well testing, leading to further problems during disposal. The content of gas at offshore platforms, unlike at refineries, also is not predictable and varies with time, and may carry significant amount of corrosive gasses, such as H ₂ S, CO ₂ , water droplets, oil droplets, etc.

[0014] Another challenge for efficient burning of hydrocarbons on offshore platforms is ensuring safe and clean conditions for personnel. For example, extended gas or oil flares create high noise, heat emission, and pollution, when the flame is not balanced with respect to fuel- oxidizer proportions. To reduce such negative effects, an open-air burner can be attached on a long boom to move the open-air burner away from the platform. In addition, sprinkling of water on the boom can be used to create a water shield behind the oil/gas burner and protect the platform from extensive heat radiation (e.g., radiated heat output from the gas/oil flame may achieve several tenths of kW/m ² ).

[0015] There are several technologies of hydrocarbon fluid disposal. For example, the first developed and commercialized tool, SeaDragon™ from Schlumberger, was employed in 1971. Although, this was a big breakthrough in the well test service, there were environmental effects.

[0016] The EverGreen™ burner from Schlumberger developed in 1991 was aimed at minimizing the environmental impact by achieving more complete combustion and enlarging the range of the wells which can be tested. With this technology, the well effluent is separated using a three-phase well-test separator, and gas is flared using a conventional gas flare tip. The EverGreen™ well-test burner can be used to burn petroleum having some remains of water.

[0017] Environmentally-clean well testing also was carried out using a multiphase flowmeter (e.g., PhaseTester™ from Schlumberger). Since this kind of flowmeter operates at a low pressure drop, it does not require the use of a gas phase separator. All the effluent from the well on the testing and production stage can be fed to transportation pipes. This approach allowed a reduction of gas flaring by 60 % (see, e.g., Y. El-Khazindar, M. Ramzi Darwish, A. Tengirsek, "Environmentally Friendly Well Testing," SPE 74106). However, such a method of total gas flare reduction does not solve the problem of liquids disposal during offshore well testing, wherein information regarding the fluid composition is not used for handling the oil combustion process.

[0018] Another approach recently developed by Schlumberger is a method for hydrocarbon disposal during well testing, including (1) separation of multiphase well effluent into gas and liquid components with further supply of the gas component to the inlet of a gas burner; (2) forwarding of the oil-water mix to a multiphase flowmeter, which provides real-time data regarding the phase composition of the liquid mixture and feeds the resulting signal regarding the water content (e.g., water cut) to a programmable controller. Information about real-time content of fluid for combustion, allows one to handle the input fluid by adding extra amount from a reserve. If the water cut is too high, the controller redirects the liquid from the oil burner to the disposal duct. Such as system provides a "smart burner" that optimizes the open air combustion for minimizing black smoke and other hazardous emissions. The system also expands the limits of burner operation in the terms of water cut in the "waste fuel." However, such system for oil burning during well testing employs a separate air compressor that would take up valuable real-estate on an offshore platform and consumes electric energy. Although the air compressor is under the control of the central processor, the inertia of the air compressor and surges in the wastes fuel supply occurring in the tested well may not allow one to achieve a smokeless combustion mode even with such a "smart burner." Moreover, the "smart burner" is designed for burning of waste fluid mainly in liquid form, wherein the gas component is burned in regular tips of a gas flare, and which have the typical disadvantages of open air gas burners.

[0019] As for burners for offshore gas combustion, there are many versions of "gas flares" (see, e.g., the series of flaring systems from John Zink Company, USA). Such burners, however, are mostly designed for production use. The special design of flare tips, involving sprinkling of water and injection of steam into the flame, allows manufacturers to construct such flare systems with lower levels of smoke, and lower noise and heat radiation, and so as to decrease significantly the boom length. However, if the produced gas carries with high amount of water or oilcontent fluid composition changes significantly and too quick , the clean performance of such flares decreases dramatically. Clean operation during well test needs to keep the air/fuel ratio close optimal and also the air flow rate involved in burning should be high.

[0020] Advantageously, the exemplary embodiments provide for universal burner for hydrocarbons, and gasses bearing some liquid (e.g., water-oil mixtures, gas, gas condensates, etc.), and with reliable operation for a wide range of waste fuels, flow rates, and compositions thereof. The exemplary universal burner also provides for low noise operation, low heat emissions toward the platform, and wind-indifference for offshore platform operation.

[0021] The idea of using the energy of flue gases for creating an air draft to other parts of installation is well known in many industries. For example, in the automobile industry, the kinetic energy of hot exhaust gas drives a special turbine. Such a high-rate turbine is installed on the same shaft as the air compressor. By rotating the shaft of the air compressor, hot gasses create a significant flow from the air filter to the input port of the air injection system (e.g., referred to as turbochargjng). Thus, the waste kinetic energy of exhaust gases is used to bolster the air intake of the internal combustion motor.

[0022] A system is described in Russian Patent application RU2,093,416 includes a safe heat generator system for filling a hot-air balloon with high-speed hot air. The heat generator includes a fan, combustion chamber with nozzles fed from the balloon, and a mixer for filling the balloon shell with a mixture of air and gaseous combustion products, wherein the mixture is driven by a fan, and the fan, a compressor and a turbine are mechanically linked. The combustion chamber is allocated downstream of the compressor and ahead of the turbine, wherein the turbine is installed on the rim of the fan and operates in a partial mode. The compressor can be volumetric. The vanes of compressor and turbine are installed on the single rotating shaft. This design creates a high-speed flow of hot air driven by the energy of the burned gas fuel (without compromising on safety of flight). However, such as system cannot be applied to the needs of wet or retrograde gas incineration.

[0023] Accordingly, the exemplary embodiments provide a clean, open-flame combustor of waste fuel that can operate in a wide range of produced gas and oil compositions, including waste fuel, and that is not sensitive to weather conditions, and which can provide tolerable heat and noise levels from an open flame and which is adapted for offshore platform applications, and the like, hi the context of the present disclosure, the term "waste fuel" can include a mixture of a complex composition and that varies from well to well, wherein such waste fuel includes a suitable amount of hydrocarbons to sustain a stable flame in open air.

[0024] Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, and more particularly to FIG. 1 thereof, there is illustrated a clean burner system 100 with air charging, hi FIG. 1, the system 100 includes a gas-turbine engine 1 (e.g., turbo-shaft, turbo-prop, turbo-fan, etc.), engine air intake 2, airscrew 3 (e.g., blades), shroud 4 of a mixing chamber 7, nozzle assembly 5, pilot light device 6, air-fuel premix chamber 7, fuel dispersion 8 in the mixing chamber 7, protective grid 9 at the air intake, flame 10, fuel dispensing unit 11 for gaseous and liquid fuel (e.g., a manifold with a set of fuel nozzles), control unit (CU) 12, oxygen/fuel ratio sensor 13 in the mixing chamber 7, flame quality sensor 14, waste fuel input 15, pipeline 16 for fuel supply to the gas-turbine engine 1, pipeline 17 for fuel supply to the premix chamber 7, pipeline 18 for gas fuel supply to the pilot light device 6, communication line 19 between the control unit 12 and fuel dispensing unit 11, communication line 20 between the control unit 12 and gas-turbine engine regulators, communication line 21 between the control unit 12 and the pilot light device 6, communication line 22 from the sensor 13 to the control unit 12, communication line 23 between the sensor 14 and the control unit 12, and an engine fuel input 27.

[0025] Advantageously, the exemplary burner system 100 can handle various types of fuel, including a waste fuel employed for feeding the gas-turbine engine 1 that drives the shaft and airscrew 3 thereof. Such a waste fuel for the gas-turbine engine 1 preferably can be methane, butane or a mixture of light gaseous olefins with a low content of hydrogen sulfide, and the like, and which can be a fraction of the waste fuel produced from a well. Such a gaseous mixture can be supplied from a gas-outlet of a liquid-gas separator included into the dispensing system 11. Such waste gaseous fuel for the gas-turbine engine 1 can be preprocessed to reduce the amount of water and hydrogen sulfide, for example, using known techniques for gas sweetening and such filter/reactor can be a part of dispensing unit 11. The reduction of H ₂ S concentration can be tolerable at level below 5-7%, for example, as demonstrated with gas microturbines from Capstone Turbine Corporation, wherein a Capstone MicroTurbine™, working in conjunction with a battery, operated on sour gas for over 1,000 hours with no performance degradation. Sour gas is untreated solution gas containing a high concentration of hydrogen sulfide (H ₂ S). The Capstone MicroTurbine™ also was able to operate on sour gas containing 5-7% percent H ₂ S in methane.

[0026] In addition, experiments regarding desulfurization of sour gas on metal zeolites and natural zeolites demonstrated the technical possibility to reduce the concentration of hydrogen sulfide to concentration less than 1% through adsorption process (see, e.g., S. Yasyerli et al., "Removal of hydrogen sulfide by cliptiolite in a fixed bed adsorber," Chemical Engineering and Processing, 41(9), pp. X785-792, 2002; and Brooks, C.S., "Desulfurization over metal zeolites," Separation Science and Technology, 25 (13-15), pp. 1817-1828, 1990). The theory of H ₂ S-specific adsorption by zeolites is further formulated in Cruz, AJ. , "Physical adsorption of H ₂ S related to the conversion of works of art: The role of the pore structure at low relative pressure," Adsorption, 1195-6, pp. 569-576, 2005). This level of hydrogen sulfide is sufficient for long-run operation of gas turbine engines described in the invention. Other options for sweetening of the input fuel for a gas turbine engine, including known chemical reactions, can be employed. If, however, the composition of gas flow is too corrosive for low-maintenance operation of the gas-turbine engine 1, a standard fuel (e.g., butane, CNG, or diesel fuel, etc.) may be provided for suitable for operation of the multi-fuel aviation gas-turbine engine 1.

[0027] hi the system 100 of FIG. 1, the pilot light device 6 flares the gas delivered from the gas outlet of gas-liquid separator of the dispensing unit 11. hi most applications, the amount of gas from the gas-liquid separator is enough for feeding both the gas-turbine engine 1 and the pilot light device 6. Such an "auxiliary" storage of fuel is only a small part of the total amount of hydrocarbons that have to be burned off by an offshore burner and is a most economic way of running the system 100, since external fuel sources are not needed.

[0028] The oxygen sensor 13 can be a lambda-type sensor (e.g., from Bosch, Germany) typically installed in the exhaust path for regulation of air injection in car engines. The sensor 13 helps to monitor the difference between the equivalence ratio for the mixture in the premix chamber 7 and the stoichiometric ratio. Most of the fuel supplied to the premix chamber 7 through fuel dispersion 8 system (e.g., fuel nozzles) is referred to as "waste fuel," which is a general term for well effluent. For example, for gas wells, such "waste fuel" can be dry gas, wet or retrograde gas or gas condensate. In oil wells, such "waste fuel" is a mixture of oil, water, and traces of gas dissolved in the fluid (e.g., what is delivered after the gas separator).

[0029] hi the case of gaseous fuel, the gas is simply injected into the premix chamber 7 through a set of tubes or nozzles. In the case of liquid waste fuel, the fuel undergoes atomization in a high-velocity air flow, wherein the design of liquid atomizers and their numbers is well known to those skilled in the relevant art(s). Atomizing through liquid nozzles creates a "mist" of liquid fuel in air that can be burned at the burner outlet. All suitable valves, chokes, filers, manifolds, and the like, that regulate the supply of such fuel can be integrated into the fuel dispensing unit 11.

[0030] The gas-turbine engine 1 operates on fuel supplied through the pipeline 16 and intakes air through the engine's air intake 2. The engine 1 rotates a shaft (not shown) with the mounted airscrew 3, creating a forced air flow 30 into premix chamber 7, and which is controlled by shroud 4. The air is taken from atmosphere and passes through the protective grid 9 (e.g., to avoid engine accidents with debris) into the premix chamber 7, where the swirled air is intensively mixed with waste fuel (e.g., gas or liquid) injected through the network of fuel dispersion 8 (e.g., fuel nozzles). The resulting fuel-air mixture is driven by the air draft through nozzle 5 and the mixture further burns in the open air (e.g., via flame 10). The pilot light 6 is employed for initial ignition of the flame 10 and for safe operation during a shut-off of the waste fuel supply. The waste fuel can be forwarded from the wellhead through the waste fuel inlet 15 to the fuel dispensing unit 11, where its composition, flow rate and other parameter (e.g., pressure and temperature) are automatically monitored (e.g., in an on-line mode using a processor, control unit, etc.). If such waste fuel is unsuitable for engine operation, it is possible to use stock engine fuel through the fuel inlet 27.

[0031] The results of the flow monitoring are sent through the communication line 19 to the control unit 12. The control unit 12 stores and processes all data obtained from the communication line 19 between the control unit 12 and the fuel dispensing unit 11, the communication line 20 between the control unit 12 and the gas-turbine engine regulators (not shown), the communication line 21 between the control unit 12 and the pilot light 6, the communication line 22 from the sensor 13 to the control unit 12, and the communication line 23 between sensor 14 and the control unit 12. The control unit 12 processes the input signals from the various communication lines and produces feedback signals (or e.g., alarm signals, etc.) for optimization of operation of the system 100. The air-in-mixture sensor 13 and flame control sensor 14 are employed for control of the processes of mixing and combustion, respectively.

[0032] FIG. 2 illustrates another exemplary gas-turbine engine clean burner system 200 with air charging. In FIG. 2, the system 200 includes the engine 1 oriented in the opposite direction as the engine 1 of FIG. 1, such that some of the working parts of gas-turbine engine 1 are located before the premix chamber 7. The system 200 operates in a similar manner as the system 100 of FIG. 1 and similar details of operation will not be described for the sake of brevity. Advantageously, the system 200 allows a reduction in the size and mass of the premix chamber 7, as well as improving the safety of the system 200 with respect to fires and explosions due to the system 200 being more open to the ambient atmosphere by virtue of the engine 1 configuration. In addition, the system 200 also provides ease of access to internal components of the engine 1, for example, in the cases of repair, maintenance, and regulation of the gas-turbine engine 1. In the system 200, the air intake 2 is oriented to provide a counterflow to the air flow produced by airscrew 3 (e.g., blades). Otherwise, the system 200 operates in a similar manner as the system 100 of FIG. 1 and the similar details of operation will not be further described for the sake of brevity.

[0033] FIG. 3 illustrates an exemplary turbo-shaft engine clean burner system 300 with air charging. In FIG. 3, a turbo-shaft engine 1 is employed and can be a better choice than the gas-turbine engine 1 of FIG. 2, since this type of aviation engine has a shaft and the air intake 2 on opposite sides, so that, advantageously, no major changes in the engine 1 and its equipment need be employed. However, any suitable turbo-shaft engines, turbo-prop engines, and the like, can be employed with any of the exemplary embodiments of this disclosure. Otherwise, the system 300 operates in a similar manner as the systems 100 and 200 of FIGs. 1-2 and the similar details of operation will not be further described for the sake of brevity.

[0034] Advantageously, some types of turbo-shaft engines 1 are tolerant to various types of fuel qualities. For example, turbo-shaft aviation engines for helicopters (e.g., Russia Mi-8 helicopters) can be employed as the engine 1 in the system 300 and advantageously can operate on gas, diesel fuel or even minimally purified crude oil. hi this respect, the multifuel turbo-shaft engine TV2-117TG (e.g., designed and produced in the USSR) can be employed as the engine 1 in the system 300 and advantageously is adapted to extreme conditions and can consume various types of fuel (e.g., with minimal modifications in the injection block), including liquid propane- butane gas and gas condensate, motor fuel for land vehicles (e.g., gasoline, kerosene, and mixtures thereof with LNG), fuel for water vehicles (e.g., diesel, crude and mixtures thereof with motor fuel), and the like. Advantageously, such an engine also includes built-in fuel-control devices that ensure startup and shutoff on kerosene fuel, filling of pipelines with kerosene for the idle period, automatic transition from one type of fuel to another, and the like. [0035] Similarly, the TV3-117 engine of all modifications made by Klimov Corporation can be employed as the engine 1 and which is designed as a gas turbine drive for mobile power stations firing diesel and gas fuel. A jet version (e.g., without free turbine module) can be used to dry premises for cattle and buildings under construction with the resulting exhaust gas jet. It also is used to blow snow and ice off the roads, railways and airfields. This brand of gas-turbine engine is relatively economical and reliable for non-traditional on-land use, and can be used as the engine 1 in the systems of the exemplary embodiments.

[0036] The design of the premix chamber 7 can vary depending of system specifications

(e.g., flow rate of waste fuel, desired air/fuel ratio, etc.). For example, for gas fuel, the gas enters to the premix chamber 7 through a set of round orifices, whereas for liquid waste fuel, such orifices can be equipped with sprinkling nozzles or injectors for fuel atomization. hi addition, the airscrew 3 can be provided with various configurations, including a single-stage or multi-stage design (e.g., such as an axial or centrifugal compressor system), with co-directional or counter- directional rotation of stages. The type and number of blades in the airscrew 3 depends on the employed air flow rate, pressure drop, and engine power.

[0037] FIG. 4 and FIG. 5 are used to illustrate exemplary systems 400 and 500, including respective variants of the mixing chamber 7 that can accommodate the variable flow rate of waste fuel. The goal of the different designs of the premix chamber 7 is to maintain a steadier "rich ratio" of air-fuel and avoid explosion risks with respect to stoichiometric mixing of the air and the gas fuel. In FIG. 4, for example, flaps 24 are employed to control the amount of air supplied to the mixing chamber 7. Advantageously, when the air flaps 24 are partially opened, this provides a reduction in the input of air (e.g., in the space between shrouds 4 and 26). This design can be employed in situations where there is a drastic change in the flow rate of well fluent or a composition thereof, and allows an operator or controller to react instantly to the changes in the flow. Such rapid changes in flow rate are typical for a well cleanup job with an unsteady wellhead flow. The process of flame regulation through the opening/closing of the air flaps 24 can be controlled by the central control unit 12 (e.g., through communication line 25), wherein a controllable portion of the forced air 30 escapes the premix chamber 7 through the flaps 24, so that the mix can remain with a same fuel/air ratio without the need for reducing the rotation (e.g., r.p.m.) of the engine 1 (e.g., wherein the engine 1 acts as an inertial system at high rotation speeds). The oxygen/fuel ratio is monitored by the oxygen sensor 13.

[0038] In FIG. 5, the system 500 can include the shroud 4 having numerous embedded shrouds 26. Advantageously, this design allows an operator to switch off the fuel injection into selected paths 8 and redistribute the waste fuel supply into other parts of premix chamber 7. Then, the fuel-rich mixtures from different parts of the shroud 4 mix with the air in the final part of the nozzle 5, facilitating clean burning of waste fuel (e.g., via the plurality of premix chamber provide by the shrouds 26). In the system 500, the air supply can include a set of tubes alternated with flow of a rich mixture in alternating tubes. This provides stages of combustion that can be used for low-NO _x combustion of natural gas, for example, as described in U.S. Patent 5,846,068, incorporated by reference herein. Advantageously, the mixing of flows with different equivalence ratio can create a pattern of clean and stable combustion. Otherwise, the systems 400 and 500 operate in a similar manner as the systems 100-300 of FIGs. 1-3 and the similar details of operation will not be further described for the sake of brevity.

[0039] In the exemplary embodiments, the premix chamber 7 can include swirling guides

(not shown) that make the flow path longer and mixing more intensive. Such swirling guides enhance the swirl number for the flow created by rotation of the airscrew 3. For the sake of brevity, the swirling guides are not depicted in drawings, but are well known in the art of burner engineering.

[0040] In the exemplary embodiments, the subsonic nozzle unit 5 ejects the air-fuel premix from the premix chamber 7 to the atmosphere for further mixing with ambient air and ignition by the pilot light 6. The subsonic nozzle 5 (e.g., a converging or diverging type nozzle) can be configured to adapt to the nominal premix flow rate (e.g., gaseous waste fuel plus air) and is well known from the art of industrial gas burners. The choice for off-the-shelf designs of the burner nozzle 5 can be dictated by the option of utilizing the kinetic energy of air-fuel flow for better mixing of the main components and reducing the jet noise (e.g., Venturi effect, swirler, shevrons, petal-type nozzle head, etc.).

[0041] The flame 10 existence is ensured by steady burning of the gas-fed pilot light 6. In the case of low gas production from a low-rate well, the pilot light 6 optionally operates as a gas flare device, wherein the waste gas is fed to the pilot light 6, and air is provided from the running of the turbine engine 1 with the airscrew 3. Accordingly, for the low gas production, the fuel dispersion network 8 and the fuel pipe 17 can be shut off.

[0042] The position of the pilot light 6 can be used for slowly controlling of the outlet cross-section of the exit nozzle 5 (e.g., by an axial shift of the pilot light 6 body). Advantageously, this can be employed at the low end of the gas burner specification with respect to fuel flow rate (e.g., to avoid flame flashback at low velocities in the premixer 7).

[0043] The sequence for start-up and shut-down of the exemplary systems 100-500, will now be described in detail, using the system 100 of FIG. 1 as an example. The safe operation of the clean burner systems 100-500 ensures that no cases of flame blowoff and flameback occur during operation. This is achieved by careful selection of air plus fuel velocity and a safe sequence of operational steps. The recommended burner system start-up procedure, for example, includes: (step 1) the control unit 12 is turned "ON"; (step 2) the control unit 12 sends a signal to cause the fuel dispensing unit 11 to open the gas supply to the pilot light device 6, with the resulting gas flare pilot light being ignited; (step 3) the flame sensor 14 monitors the existence of a flame from the pilot light 6 (e.g., wherein a "NO" signal causes a command from the control unit 12 for system shut-off); (step 4) if the flame is "ON", the control unit 12 sends an order to fuel the dispensing unit 11 for supplying engine-quality fuel (e.g., gas or liquid fuel) to the gas- turbine engine 1 ; (step 5) the gas-turbine engine is "ON"; (step 6) if the gas-turbine engine 1 is "ON", the control unit 12 allows the injection of the waste fuel through the fuel distribution pipeline 8 (e.g., fuel nozzles), and if the engine 1 fails to run, the control unit 12 sends the order for burner system 100 shut-down in the reverse order, as above; (step 7) with the engine 1 running, the airscrew 3 provides air charging for clean combustion of the waste fuel, wherein the operation is steady under minor regulation of the flame through feedback from the control unit 12 (e.g., more input waste fuel requires more air supply, i.e., higher power from the gas turbine engine 1); (step 8) if the flame sensor 14 gives a positive "YES" signal and the oxygen-in-fuel sensor 13 detects the proper amount of oxygen in the premix chamber 7 via a "YES" signal, the operation of the burner system 100 continues, wherein if there are no proper signals indicating safe combustion, the control unit 12 shuts down components in the reverse order. The system 100 shutdown can be carried out in the reverse order of the steps described above. The start-up and shut-down of the exemplary systems 200-500 can be performed in a similar manner as the systems 100 of FIG. 1 and will not be further described for the sake of brevity.

[0044] The following estimations further detail the clean burner systems 100-500 with air turbocharging. The following example illustrates the system 100 of FIG. 1 used for combustion of gas from a gas-producing well.

[0045] According to the theory of ideal airscrews (see, e.g., "The Elements of Aerofoil and Airscrew Theory," by H.Glauert, Cambridge University Press, 1983, p. 201), the formula of equivalence for power on a shaft can be given by:

N(= Pv ,

[0046] where N is the power of engine conveyed to the shaft (W), I is the airscrew efficiency, P is the aircrew thrust (N), and v (m/s) is the air flow velocity downstream of the airscrew .

[0047] On another hand, the expression for the thrust can be given by:

P = 25(1^2 ,

[0048] where S is the area covered by the airscrew in m ² (e.g., the cross-section area of premix chamber 7), and I is the air density in kg/m ³ . Since one can formulate the volumetric flow rate through the propeller as G _v = vS _t this gives us a simple formula for the volumetric flow rate of air as a function of power taken by the shaft that drives the airscrew:

[0049] Let us make an estimation for the Mi-8 helicopter's multi-fuel gas-turbine engine

TV2 117TG, which has a nominal power of 1000 h.p. (e.g., on the shaft) for cruise operation mode, wherein the values are taken from the manufacturer's specifications. One then takes the aircrew efficiency as 0.8 (e.g., which depends on design and number of blades), and the air density at atmospheric conditions and temperature of O ⁰ C equal to 1.2 kg/m ³ . The airscrew span is 1.5 m and this provides the estimation for the air flow rate, which is forced (e.g., charged) into the premix chamber 7, as follows:

[0050] Now, one estimates the amount of waste gas which is flared under atmospheric pressure, under the assumption of the rich fuel limit for an air-fuel mixture, wherein for a methane-air mixture the rich flammability limit in air is 15%, and for a propane-air mix the rich flammability limit in air is 10.1% (see, e.g., "Industrial Burners Handbook," edited by Charles E. Baukal, Jr., p. 26), as follows: r ¹⁵ r «

^6c » ^« - 100 - 15^ = 16.2 [m ³ /s];

10,1

^G CiH _a - 1 _i 0 _nft 0 -'i 1n0,Λ1 " ^v -- 10.3 [πrVs].

[0051] These numbers are then recalculated into 50 and 32 MMSCFD (i.e., oilfield metric system), respectively. Such calculated proportion of fuel and oxidizer (e.g., air) components is near to optimal for the mixture at the nozzle inlet 5 of FIG. 1 (e.g., wherein a shortage in the feeding of the gas will reduce the safety of the system 100 with respect to explosions, and a higher proportion of the gas to air will result in less clean combustion of methane fuel).

[0052] The above example demonstrates that the engine 1 of the system 100 of FIG. 1, with a standard power, creates the air forced flow that fits the level of fuel outflow during well testing operations. In addition, several burner system 100 installations can be configured in parallel for operations with a higher flow rate.

[0053] For the same level of air charging through the premix chamber 7, one can easily estimate the exit velocity out from the nozzle 5 (e.g., configured as round tube), as follows:

IV = (G} _V + G _CHΛ

[0054] The moderate level of exit velocity indicates that the flow is in the subsonic range.

Advantageously, such exit velocity ensures flow pattern stability at moderate winds and with no flashback.

[0055] The engine 1 (e.g., multi-fuel TV2 117TG model) specification gives us the specific fuel combustion (e.g., cruise mode of engine operation) at the level of 310 gram per 1 horse-power (e.g., for 1 hour). Taking the methane specific density at standard conditions equal to 0.55, one can estimate the fuel volumetric rate through the gas-turbine engine 1 equal to 0.16 m ³ /s. Advantageously, such estimate indicates a high efficiency of air charging in the system 100, wherein the ratio of gaseous fuel (e.g., clean fuel) consumed by the gas-turbine engine 1 to the total amount of gas burnt (e..g, waste fuel) is less than about 1%.

[0056] Advantages of the clean burner systems 100-500, for example, further include the burner systems being universal and capable of burning gas, wet or retrograde gas, oil-water mixtures, and the like; lower soot and lower heat emissions after combustion due to premixing with air; a stable and clean flame, even at moderate amounts of water droplets and CO ₂ in the well effluent; low mass and size of the systems (e.g., relative to the engine power); operation over a wide range of fuel flow rates; monitoring and regulating of burner processes in real time via the control unit 12; swirled and turbulent flow after the airscrew 3 providing for better mixing in the premix chamber 7; the waste fuel employed being in gaseous or liquid form (e.g., with different fuel nozzles being employed); providing for use of a market-available, poly-fuel engine 1 with integrated control system; high-speed, turbulent and swirled air flow in the premix chamber 7 facilitating atomization of liquid waste fuel; and a high-speed, turbulent and swirled flow which exits the nozzle 5 facilitating the further mixing with atmospheric air at the outlet. Similar estimations can be performed to detail the clean burner systems 100-500 with air turbocharging for use with various types engine, fuel gasses, waste gasses, wells, and the like, as will be appreciated by those skilled in the relevant arts.

[0057] The above-described devices and subsystems of the exemplary embodiments can include, for example, any suitable servers, workstations, personal computers (PCs), laptop computers, personal digital assistants (PDAs), Internet appliances, handheld devices, cellular telephones, wireless devices, other electronic devices, and the like, capable of performing the processes of the exemplary embodiments. The devices and subsystems of the exemplary embodiments can be configured to communicate with each other using any suitable protocol and can be implemented using one or more programmed computer systems or devices.

[0058] One or more interface mechanisms can be used with the exemplary embodiments, including, for example, Internet access, telecommunications in any suitable form (e.g., voice, modem, and the like), wireless communications media, and the like. For example, the employed communications networks can include one or more wireless communications networks, cellular communications networks, 3 G communications networks, Public Switched Telephone Network (PSTNs), Packet Data Networks (PDNs), the Internet, intranets, a combination thereof, and the like.

[0059] It is to be understood that the devices and subsystems of the exemplary embodiments are for exemplary purposes, as many variations of the specific hardware and/or software used to implement the exemplary embodiments are possible, as will be appreciated by those skilled in the relevant art(s). For example, the functionality of one or more of the devices and subsystems of the exemplary embodiments can be implemented via one or more programmed computer systems or devices.

[0060] To implement such variations as well as other variations, a single computer system can be programmed to perform the special purpose functions of one or more of the devices and subsystems of the exemplary embodiments. On the other hand, two or more programmed computer systems or devices can be substituted for any one of the devices and subsystems of the exemplary embodiments. Accordingly, principles and advantages of distributed processing, such as redundancy, replication, and the like, also can be implemented, as desired, to increase the robustness and performance the devices and subsystems of the exemplary embodiments.

[0061] The devices and subsystems of the exemplary embodiments can store information relating to various processes described herein. This information can be stored in one or more memories, such as a hard disk, optical disk, magneto-optical disk, RAM, and the like, of the devices and subsystems of the exemplary embodiments. One or more databases of the devices and subsystems of the exemplary embodiments can store the information used to implement the exemplary embodiments of the present disclosure. The databases can be organized using data structures (e.g., records, tables, arrays, fields, graphs, trees, lists, and the like) included in one or more memories or storage devices listed herein. The processes described with respect to the exemplary embodiments can include appropriate data structures for storing data collected and/or generated by the processes of the devices and subsystems of the exemplary embodiments in one or more databases thereof.

[0062] All or a portion of the devices and subsystems of the exemplary embodiments can be conveniently implemented using one or more general purpose computer systems, microprocessors, digital signal processors, micro-controllers, and the like, programmed according to the teachings of the exemplary embodiments of the present disclosure, as will be appreciated by those skilled in the computer and software arts. Appropriate software can be readily prepared by programmers of ordinary skill based on the teachings of the exemplary embodiments, as will be appreciated by those skilled in the software art. hi addition, the devices and subsystems of the exemplary embodiments can be implemented by the preparation of application-specific integrated circuits or by interconnecting an appropriate network of conventional component circuits, as will be appreciated by those skilled in the electrical art(s). Thus, the exemplary embodiments are not limited to any specific combination of hardware circuitry and/or software. [0063] Stored on any one or on a combination of computer readable media, the exemplary embodiments of the present disclosure can include software for controlling the devices and subsystems of the exemplary embodiments, for driving the devices and subsystems of the exemplary embodiments, for enabling the devices and subsystems of the exemplary embodiments to interact with a human user, and the like. Such software can include, but is not limited to, device drivers, firmware, operating systems, development tools, applications software, and the like. Such computer readable media further can include the computer program product of an embodiment of the present disclosure for performing all or a portion (if processing is distributed) of the processing performed in implementing the exemplary embodiments. Computer code devices of the exemplary embodiments of the present disclosure can include any suitable interpretable or executable code mechanism, including but not limited to scripts, interpretable programs, dynamic link libraries (DLLs), Java classes and applets, complete executable programs, Common Object Request Broker Architecture (CORBA) objects, and the like. Moreover, parts of the processing of the exemplary embodiments of the present disclosure can be distributed for better performance, reliability, cost, and the like.

[0064] As stated above, the devices and subsystems of the exemplary embodiments can include computer readable medium or memories for holding instructions programmed according to the teachings of the present disclosure and for holding data structures, tables, records, and/or other data described herein. Computer readable medium can include any suitable medium that participates in providing instructions to a processor for execution. Such a medium can take many forms, including but not limited to, non-volatile media, volatile media, transmission media, and the like. Non-volatile media can include, for example, optical or magnetic disks, magneto-optical disks, and the like. Volatile media can include dynamic memories, and the like. Transmission media can include coaxial cables, copper wire, fiber optics, and the like. Transmission media also can take the form of acoustic, optical, electromagnetic waves, and the like, such as those generated during radio frequency (RF) communications, infrared (IR) data communications, and the like. Common forms of computer-readable media can include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other suitable magnetic medium, a CD-ROM, CDRW, DVD, any other suitable optical medium, punch cards, paper tape, optical mark sheets, any other suitable physical medium with patterns of holes or other optically recognizable indicia, a RAM, a PROM, an EPROM, a FLASH-EPROM, any other suitable memory chip or cartridge, a carrier wave, or any other suitable medium from which a computer can read.

[0065] While the present disclosure has been described in connection with a number of exemplary embodiments, and implementations, the present disclosure is not so limited, but rather cover various modifications, and equivalent arrangements, which fall within the purview of the appended claims.