KR20060101159A - Liquid-gas tanker with a combustor unit for burning boil-off gas - Google Patents

Abstract

The present invention provides a liquefied gas tanker having a combustor unit 10 for combusting a boy-off gas. A vortex combustor 28 having a gas supply device 42 for supplying the boil-off gas to the combustor unit 10 and the combustion air supply means 40, and a combustion chamber 30 for completely burning the gas using the combustion air. And mixing means 32 and 64 for mixing the flue gas from the combustion chamber 30 with the mixed air. Vortex combustor 28 has a burner head 46 inclined conically toward the outlet diameter d, adjacent thereto of a cylindrical shape having a diameter equal to the outlet diameter and a length l of at least 20% of the outlet diameter. The stabilization zone 48 is arranged, and adjacent to the stabilization zone 48 is a cylindrical precombustion chamber 50 having a large diameter and a ratio of the length L to the diameter D of at least L / D = 0.33, Adjacent to the pre-combustion chamber 50, a cylindrical post-combustion chamber 60 whose diameter is larger than the diameter of the pre-combustion chamber and whose length is larger than the diameter is disposed, and a plurality of outlets through which the mixing means enables a plurality of flue gas ejections. It has a truncated cone-shaped outlet region 62 provided with a ball 64 and a mixed air supply pipe 32 conically surrounding the outlet region.

Liquefied gas tankers, boiler-off gas, vortex burners, pre-combustion chambers and post-combustion chambers

Description

LIQUID-GAS TANKER WITH A COMBUSTOR UNIT FOR BURNING BOIL-OFF GAS}

1 is a schematic configuration diagram of a liquefied gas tanker according to the present invention having a combustor unit.

2 is a side view of the combustor unit.

3 is a side view showing a part of the combustor unit shown in FIG.

4 is a perspective view of a variant embodiment of a combustor unit having a closed annular pipeline for mixing the boil-off gas into the cooled mixed air (if the burner fails).

Explanation of Signs of Major Parts of Drawings

10 ... combustor unit 14 ... liquefied gas tanker

28 ... Vortex burner 30 ... Combustion chamber

32 ... Mixed air supply pipe 46 ... Burner head

48. Stabilization zone 50 ... All combustion chamber

60 ... Afterburn chamber 62 ... Exit area

64.Outlet

The present invention relates to a liquefied gas tanker having a combustor unit for combusting a boiler-off gas generated for technical reasons in all liquefied gas tankers or liquefied gas carriers.

Due to the limited thermal expansion of liquefied gas tanks and also limited pressure resistance in liquefied gas tankers, gases that steadily evaporate in constant amounts from cryogenically cooled liquefied gases (eg liquefied gases such as natural gas, methane, hydrogen, butane) It is necessary to handle it safely. The best solution is to consume this gas directly from the tanker for propulsion and other uses of the tanker. Conventional liquefied gas tankers, in particular liquefied gas tankers with gas engines, are used for this purpose. However, since the engine stops (such as anchoring at the harbor) regularly, this use is not sufficient and it has been proposed to reliquefy or burn such a boil-off gas in view of other treatments or treatability. In case of failure, it is necessary to maintain safety, but total reliquefaction of the generated gas is expensive, and therefore, gas that cannot be used for propulsion is generally burned and disposed of.

In the combustion of the boil-off gas, the exhaust gases generated for safety reasons shall not exceed a maximum temperature of 450 ° C in accordance with current regulations. However, this results in a significant increase in the amount of boil-off gas when the propulsion is stopped and a large amount of mixed air is required to reach a relatively low final temperature of 450 ° C., which must be mixed during or after combustion. Such air mixing cannot be easily achieved technically since it must be carried out so that hot gas is not emitted from the funnel.

It has also been proposed to allow the generated boil-off gas to be combusted in flame ejection pipes installed on the deck of the ship and to ensure that freely ejected flames are not accessible to other superstructures of the ship as much as possible, but the wind conditions are poor. If not, this is an exception and this is not satisfactory from a safety point of view.

It is an object of the present invention to provide a safe, cost-effective, safe and complete combustion of the generated boil-off gas and to ensure that the flame is stabilized even when a large amount of air is supplied. To provide a solution for combustion.

The present invention provides a liquefied gas tanker having a combustor for combusting a boy-off gas, the present invention is a vortex combustor having a gas supply device and a combustion air supply device for the combustor unit to supply a boy-off gas, combustion air Wherein the vortex burner has a burner head inclined in a conical shape toward the outlet diameter side, wherein the combustion chamber comprises a combustion chamber for completely burning the gas by using Adjacent to the head is a cylindrical stabilization zone having a diameter equal to the exit diameter and at least 20% of the exit diameter, the cylindrical stabilization zone having a large diameter to diameter ratio of at least L / D = 0.33 adjacent the stabilization zone. The combustion chamber is disposed adjacent to the combustion chamber, the diameter is larger than the diameter of the combustion chamber and the length The cylindrical post-combustion chamber is arranged, and the mixing means has a truncated cone-shaped outlet area having a plurality of outlet holes for allowing a plurality of flue gas ejections and a mixed air supply pipe surrounding the outlet area in a conical shape. do.

The combination of these means of fluid technology effect allows very dense flames to be generated and combusted stably and reliably even when a large amount of air is supplied. Is not included and the exhaust gas can be easily controlled.

The length of the cylindrical stabilization zone may be 25%, 30% or 40% of the exit diameter or may be a value between these values.

The L / D ratio of the precombustion chamber may be at least 0.5, 0.75, 1.0 or 1.25.

Also, in order to effectively mix the flue gas with the mixed air, a vortex device may be provided for rotating the supplied mixed air in a vortex.

The invention also provides a mixed air supply pipe arranged concentrically around the combustion chamber.

The truncated conical outlet region of the mixing means may also comprise a cone having a half angle of about 30 ° with respect to the longitudinal axis of the combustion chamber.

Referring to the present invention in more detail based on the accompanying drawings as follows.

1 shows a configuration according to the invention of the combustor unit 10 according to FIGS. 2 and 3 in the funnel 12 of a liquefied gas tanker 14, in which the gas engine of the tanker is also located. The exhaust line or funnel of (16) is arranged and substantially the combustor unit may be integrally formed in a funnel structure which may already be constructed or otherwise provided.

The combustion gas is supplied in the form of a boil-off gas to the combustor unit through a supply line 20 and a safety control unit 22 communicating with the vessel's liquefied gas tank. The safety control unit 22 simply comprises a safety shutoff valve and a pressure controller for supplying the combustion gas under constant pressure (generally below 200 millibars) to the combustor unit under control by evaporation from the tank.

2 and 3 show a combustor unit 10 used in accordance with the present invention. FIG. 2 is a side view and FIG. 3 is a side view showing a portion in cross section.

The combustion unit is mounted vertically to the mounting frame 26 so that the exhaust gas generated can rise vertically to the atmosphere. Vortex combustor 28 is operable in combustion chamber 30 and is surrounded by a mixed air supply pipe 32 constituting an outer jacket. Two axial flow fans 36 transfer the mixed air to the annular zone 38 between the combustion chamber 30 and the mixed air supply pipe 32 and each inlet is tangentially disposed as shown in FIG. By acting on the supplied mixed air, it is possible to effectively mix the flue gas supplied to the downstream side.

The combustion air fan 40 transfers combustion air to the vortex combustor 28 to which combustion gas is supplied through the gas pipe 42 by a control unit (not shown).

Vortex combustor 28 has a burner head 46 inclined in a conical shape toward the outlet diameter d side through which the vortex movement is augmented while combustion air passing through the vortex vortex moves. Adjacent to burner head 46 is a cylindrical stabilization zone 48, the diameter of which is equal to the outlet diameter d of the burner head and its length is about 20% of its diameter. This area, which is embedded in the refractory, serves to improve the stabilization of the flame. A cylindrical precombustion chamber 50 having a larger diameter D is arranged in proximity to the stabilization zone 48. In this embodiment, the length L of the precombustion chamber 50 is approximately equal to the diameter D thereof.

An additional air supply line is led from the combustion air fan 40 to the annular space 58 through the connection 56. This annular space surrounds the pre-combustion chamber and the stabilization zone 48 and is formed axially in the post-combustion chamber 60 disposed downstream of the through-combustion chamber of the pre-combustion chamber 50 extending tangentially and radially. It is possible to supply the mixed air to the combustion chamber through the through hole.

The cylindrical post-combustion chamber 60 ends in a truncated conical outlet region 62 having a larger diameter than that of the pre-combustion chamber 50 and provided with a plurality of radially and axially inclined outlet holes 64.

The post-combustion chamber 60 and the outlet region 62 are preferably composed of sheets of stainless steel having fire and corrosion resistance, but they may be used for other materials. An end portion of the outlet region 62 extending substantially transverse to the longitudinal axis 66 of the combustor unit is closed by an end wall 68 extending transversely with respect to the longitudinal axis 66.

The mixed air supply pipe 32 together with the combustion chamber forms an annular region 38 in the form of a concentric annular gap, through which the mixed air is guided until it meets the flue gas ejected from the outlet hole 64. After mixing with the flue gas, it is discharged in the form of cooled exhaust gas from the upper end 70 of the converging- diverging type of the mixed air supply pipe 32.

At two or more air ratios, the gas is burned almost completely in the precombustion chamber at a temperature of about 1,200 ° C. Smoke-free complete combustion takes place in the post-combustion chamber. When leaving the post-combustion chamber through the outlet hole 64, flue gas is divided into a plurality of jet classifications so that intensive mixing can be achieved at a very short distance, and mixing of mixed air and flue gas (exhaust gas) passes through a short distance. After the temperature reaches 450 ℃ or less so that the height of the funnel at the upper side of the outlet hole 64 can be kept low.

The use of an axial fan to allow a substantial portion of the air (mixed air) to be supplied far away due to the relatively low pressure level is consumed by the fan by allowing the mixing of flue gases advantageously through each jet stream directed towards the mixed air side. This reduces the power required to save on electricity costs. In addition, the axial fan is relatively compact, it is possible to reduce the installation space. By efficiently configuring the structure of the combustion chamber, such as the vortex combustion chamber, the present invention provides substantial advantages with regard to the specific space and safety situation of the liquefied gas tanker.

4 shows a variant embodiment of the combustor unit, inlet 81 (connected not shown), which is arranged outside the mixed air supply pipe 32 and connected to the gas pipe 42 for supply of the boil-off gas. And a closed annular pipeline 80 having a negative) and a combustor failure valve (not shown) of a controlled type. A plurality of mixing lines 82 extend radially inward from the closed pipeline 80 to end inside the mixed air supply pipe 32 and act to mix the boil-off gas into the mixed air in the event of a combustor failure. do. In such a case, the mixed air cooled to the extent that the mixture is no longer ignited with the boil-off gas, which normally has to be combusted at a short distance downstream of the closed annular pipeline or downstream of the outlet hole 64. Mix with By such safe means, if the combustor fails, the boy-off gas can be released into the safe zone in the unburned state without causing any obstacles that may render the combustor unable to restart for any reason.

The closed annular pipe line 80 may be disposed inside or outside the mixed air supply pipe 32, but as illustrated, a special temperature resistance is not required.

As such, the present invention provides a liquefied gas tanker that allows safe, cost-effective and safe and complete combustion of the generated boil-off gas.

Claims (8)

As a liquefied gas tanker 14 having a combustor unit 10 for combusting a boil-off gas, a gas supply device 42 and combustion air supply means 40 in which the combustor unit 10 supplies the boil-off gas. Vortex combustor 28 having a combustion chamber, combustion chamber 30 for completely burning the gas using the combustion air, and mixing means (32, 64) for mixing the flue gas from the combustion chamber 30 with the mixed air In which the vortex burner 28 has a burner head 46 inclined conically toward the outlet diameter d, adjacent to which the diameter is equal to the outlet diameter and the length l is at least 20% of the outlet diameter. The cylindrical stabilization zone 48 is arranged, and adjacent to the stabilization zone 48 is a cylindrical pre-combustion chamber 50 having a large diameter and a ratio of the length L to the diameter D of at least L / D = 0.33. The diameter of the precombustion chamber adjacent to the precombustion chamber 50 A cylindrical post-combustion chamber 60 having a large length and larger than its diameter is disposed, and a truncated cone-shaped outlet region 62 having a plurality of outlet holes 64 for allowing a plurality of flue gas ejections to be mixed. Liquefied gas tanker characterized in that it has a mixed air supply pipe (32) surrounding the outlet area in a conical shape. A liquefied gas tanker according to claim 1, wherein the length l of the stabilization zone is 25%, 30% or 40% of the outlet diameter d. The liquefied gas tanker according to claim 1 or 2, wherein the L / D ratio is 0.5, 0.75, 1.0 or 1.25. The liquefied gas tanker according to any one of the preceding claims, wherein a vortex device is provided to impart vortex motion to the supplied mixed air. A liquefied gas tanker according to any of the preceding claims, characterized in that the mixed air supply pipe (32) is arranged concentrically around the combustion chamber (30). A liquefied gas tanker according to any of the preceding claims, characterized in that the truncated conical outlet region (62) of the mixing means comprises a cone having a half angle of about 30 ° with respect to the longitudinal axis (66) of the combustion chamber (30). The method according to any one of the preceding claims, wherein a closed annular pipeline (80) is arranged in the mixing means (32, 64) for mixing the boil-off gas into the mixed air in the event of a combustor failure. Liquefied gas tanker, characterized in that the line (82) extends radially inward from the closed pipeline and ends at the inside of the mixing means (32, 64). 8. The liquefied gas tanker according to claim 7, wherein the closed annular pipe line (80) is disposed inside or outside the mixed air supply pipe (32).

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