JP2014173689A - Submerged combustion vaporizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable additive agent such as neutralizer to be safely and positively fed even during an operation of submerged combustion vaporizer.SOLUTION: Air supplied from a blower 14 and fuel supplied from a fuel supplying source are ignited by a burner 2 arranged at a downcomer 13 immersed in a water tank 11, its combustion gas is injected into water through a purge pipe 15 to generate air bubble and low temperature liquefied gas passed in a bundle of heat transfer pipes 12a is gasified by a heat exchanger 12 having a bundle of heat transfer pipes 12a immersed and arranged in the water tank 11. Additive feeding pipe 20 of which lower end extends from at least a water surface W downward is installed in the water tank 11 at this submerged combustion type vaporizer 1 and then additive agent can be fed from the upper end side into water.

Description

  The technology disclosed herein relates to an underwater combustion type vaporizer, and more particularly to a structure in which an additive such as a neutralizing agent is introduced into the water tank.

  As one of vaporizers for low-temperature liquefied gas such as liquefied natural gas, an underwater combustion type vaporizer (Submerged Combustion Vaporizer) is known (see, for example, Patent Document 1). This submerged combustion type vaporizer is provided in a downcomer immersed in a water tank and burns air supplied from a blower and fuel supplied from a fuel supply source in a combustion chamber, and the combustion gas is passed through a sparge pipe. An underwater combustion burner configured to be ejected into the water, and a heat exchanger having a heat transfer tube bundle immersed in the water tank, and the combustion gas ejected as bubbles in the water is contained in the water tank. By heating the low-temperature liquefied gas passing through the heat transfer tube bundle while stirring the water, the low-temperature liquefied gas is vaporized.

  In such an underwater combustion type vaporizer, the pH of the water in a water tank falls gradually under the influence of the nitrogen oxide contained in combustion gas. Since this acidified water cannot be drained as it is, it is necessary to add a neutralizing agent as appropriate. Commonly used neutralizing agents are alkaline powder materials such as sodium bicarbonate (sodium bicarbonate) that are readily available and easy to handle. It is known that a neutralizing agent made of this powder material is introduced using a scoop or the like from a manhole provided on a top plate covering a water tank.

  When a powder material is introduced, it is necessary to deal with the dust. For example, in the powder dissolving apparatus of Patent Document 2, the air in the tank is exhausted after passing the filter layer and the water storage.

Japanese Utility Model Publication No. 5-75599 JP 2001-25649 A

  During operation of the underwater combustion type vaporizer, the discharge air from the blower and the combustion gas of the burner are sent into the water in the water tank and exhausted vigorously from the chimney stack that communicates with the atmosphere provided above the water tank. Therefore, exhaust gas is blown over the water surface of the water tank. For this reason, if it is going to throw in a neutralizer with scoop etc. from opening parts, such as a manhole, there exists a problem that a neutralizer scatters and cannot be thrown in. Further, since the combustion gas must be exhausted vigorously from the stack and the filter and the water storage cannot be passed as in Patent Document 2, even if the neutralizing agent can be forcibly thrown, The part may be released from the stack without reaching the water. For this reason, the neutralizing agent charging operation could be performed only when the operation was stopped.

  The present invention has been made in view of such a point, and an object of the present invention is to make it possible to safely and reliably add a neutralizing agent even during operation.

  In order to achieve the above object, according to the present invention, a dedicated additive charging pipe having a lower end extending downward from the water surface is provided.

Specifically, in the first invention, the combustion gas is provided by burning the air supplied from the blower and the fuel supplied from the fuel supply source provided in the downcommer immersed in the water tank in the combustion chamber. A burner configured to generate bubbles by jetting into the water through a small hole provided in the sparge pipe;
An underwater combustion type vaporizer having a heat transfer tube bundle immersed in the water tank and a heat exchanger configured to vaporize a low-temperature liquefied gas passing through the heat transfer tube bundle To do.

  And in the said water tank, the lower end is extended at least below the water surface, and the additive injection pipe | tube which makes an additive introduce | transduce into the said water from the upper end side is provided.

  According to this configuration, since the lower end of the additive charging pipe extends downward from the water surface, the exhaust gas on the water surface does not enter the additive charging pipe. For this reason, since an additive does not scatter when throwing in an additive, it is not necessary to stop an underwater combustion type vaporizer. Here, the “additive” includes a neutralizing agent, an antiseptic, a bactericide and the like, and is not particularly limited. The “downcomer” indicates a hollow tube whose lower end is immersed in a water tank, and air and fuel are supplied from the upper end side. The “sparge pipe” is a tubular member in which a large number of small holes for injecting combustion gas into water are formed, and the arrangement configuration is not particularly limited.

  The additive charging pipe may be disposed so as to avoid a bubble region where the combustion gas bubbles are generated. In this case, since the additive injection tube is out of the bubble region, it is not difficult to add the additive due to the influence of the bubbles rising rapidly. For this reason, an additive can be injected | thrown-in more safely and reliably. The “bubble region” means a region almost immediately above the region where the small holes of the sparge pipe are provided and a large amount of bubbles are generated vigorously and the water surface rises more than other regions.

  In addition, it is desirable that the additive charging pipe has a lower end inserted deeper than a region where the water surface is swung by the bubbles. According to this configuration, even if the water surface fluctuates due to the influence of combustion gas bubbles, the lower end of the additive charging pipe does not appear on the water surface, so that the additive can be charged more safely and reliably. Here, the “swing region” indicates a range from the minimum water level to the maximum water level that fluctuates up and down with respect to a predetermined water level due to the influence of combustion gas bubbles and the like.

  Moreover, the said additive injection | throwing-in pipe | tube is good to insert the lower end in the area | region where downward flow generate | occur | produces, such as the circumference | surroundings of the bubble area | region by the combustion gas in a water tank. In this case, the added additive is rapidly stirred in the water tank along the downward flow. The “region where the downward flow is generated” mainly occurs around the bubble region.

  Furthermore, the lower end of the additive charging pipe may be disposed above the small hole of the sparge pipe. In this case, the additive thrown in by the bubbles efficiently spreads into the water tank.

  As described above, according to the present invention, the additive is provided even during operation by providing the additive input pipe in which the lower end extends at least below the water surface in the water tank and the additive is introduced into the water from the upper end side. Can be inserted safely and reliably.

It is a schematic front view which fractures | ruptures and shows the structure of an underwater combustion type vaporizer. It is a schematic plan view which shows the structure of an underwater combustion type vaporizer.

  Hereinafter, an embodiment of an underwater combustion type vaporizer will be described based on the drawings. FIG.1 and FIG.2 has shown the outline of the underwater combustion type vaporizer 1. FIG. This underwater combustion type vaporizer 1 is a liquefied natural gas (LNG) vaporizer, and is immersed in, for example, a rectangular parallelepiped water tank 11, and a large number of heat transfer tubes 12a serving as LNG channels are bent in multiple stages. A heat exchanger 12 formed by molding is provided. One end of the heat exchanger 12 communicates with an LNG introduction pipe 12b serving as an LNG inlet, and the other end communicates with an NG exhaust pipe 12c that discharges vaporized natural gas (NG). In FIG. 1, the bundle of heat transfer tubes 12 a is illustrated in a simplified manner, but actually, multiple rows of heat transfer tubes 12 a are arranged at the depth of FIG. 1 and communicate with each other (in FIG. 2, simplified). Omitted for). The number and arrangement of the heat transfer tubes 12a are not particularly limited as long as heat exchange can be performed efficiently.

  The water tank 11 is covered with, for example, a rectangular plate-shaped top plate 11a. The top plate 11 a can be walked by an operator, and is arranged so that a cylindrical downcomer 13 is immersed in the water tank 11 at a predetermined position.

  A burner 2 is provided at the upper end of the downcomer 13 to burn the fuel gas supplied from a fuel gas supply source (not shown) through the fuel supply pipe 6 and the air supplied through the blower 14.

  At the bottom of the water tank 11, there is disposed a sparge pipe 15 that communicates with the downcomer 13 and is formed with a large number of small holes 15 a through which the combustion gas of the burner 2 is ejected. Although only one sparge pipe 15 is depicted in FIG. 1, in reality, a large number of sparge pipes 15 are arranged as shown in FIG. 2, and at least the entire heat transfer tube 12a is covered with bubbles B containing combustion gas. ing. The number and arrangement of the sparge pipes 15 are not particularly limited, and it is only necessary to arrange the small holes 15a in order to diffuse the bubbles B evenly and efficiently. The small holes 15a may be provided uniformly or randomly in the sparge pipe 15, and are preferably provided mainly on the upper surface and side surfaces thereof. As shown in FIG. 1, the water surface W rises more than other portions due to the rising airflow in the bubble region A where the bubbles B reach (so-called air lift effect). The “bubble region A” means a region where a large amount of bubbles B are generated almost immediately above the region where the small hole 15a of the sparge pipe 15 is provided. In practice, a small amount of bubbles are also generated outside the bubble region A.

  The top plate 11a of the water tank 11 is provided with a chimney stack 16 for exhausting combustion exhaust gas, and its upper end communicates with the atmosphere.

  The underwater combustion type vaporizer 1 ejects the combustion gas of the burner 2 as bubbles B into the water tank 11 through the small holes 15a of the sparge pipe 15, thereby passing the heat exchanger 12 while stirring the water in the water tank 11. LNG to be heated. As a result, LNG is vaporized into NG, and this is sent out from the outlet of the NG discharge pipe 12c. The underwater combustion type vaporizer 1 is capable of stirring the water in the water tank 11 by jetting the combustion gas as bubbles B into the water tank 11 and reducing the temperature of the combustion exhaust gas discharged from the stack 16. Therefore, it has the feature that the thermal efficiency is extremely high.

  A cylindrical additive feeding tube 20 is provided outside the bubble region A in the water tank and at a position close to the bubble region A so that the lower end extends slightly below the water surface W. The upper end side of the additive charging tube 20 is fixed substantially vertically to the top plate 11a. A downward flow C in which the water that has risen vigorously due to the bubbles B descends is generated just outside the bubble region A. For this reason, as for the additive injection pipe | tube 20, it is desirable that the lower end is inserted in the area | region where the downward flow in the water tank 11 generate | occur | produces. The additive charging pipe 20 is made of, for example, a stainless steel pipe, and a lid member 21 that can be opened and closed is provided at the upper end thereof. The lid member 21 is connected to the upper end of the additive charging pipe 20 by, for example, a hinge part (not shown). Since the additive charging pipe 20 is not usually subjected to a large load, the thickness may be about 3 mm, and the flange 22 provided on the outer periphery thereof is fixed to the opening periphery provided on the top plate 11a. Because of such a simple structure, even if the underwater combustion type vaporizer 1 is not provided with the additive charging pipe 20 from the beginning, the top board 11a is processed on the spot and the additive charging pipe 20 is attached. May be. The additive feeding pipe 20 may be, for example, about 250 mm in outer diameter so that the powdery neutralizing agent can be fed with a scoop or the like, and is attached so as to be immersed in the water surface W, for example, about 200 mm. The distance of the lower end portion from below the water surface W is at least below the swinging range of the water surface W. The rocking of the water surface W is caused by an air lift effect generated by the underwater combustion type vaporizer 1. On the other hand, if the lower end of the additive charging pipe 20 extends too far downward, it is not appropriate in terms of stirring efficiency, and it is preferable that it be disposed at least above the small hole 15a of the sparge pipe 15. A maintenance manhole 23 is provided in the vicinity of the additive charging tube 20.

-How to use the additive charging pipe-
By operating the underwater combustion type vaporizer 1, the pH of the water in the water tank 11 gradually decreases due to the influence of nitrogen oxides and the like contained in the combustion gas. In order to avoid the adverse effect of excessively low pH, for example, powdered baking soda is added as an additive when a predetermined time has elapsed or when the pH has decreased below a predetermined value.

  A predetermined amount of baking soda is prepared while the submerged combustion type vaporizer 1 is operated, and the lid member 21 of the additive charging pipe 20 is opened toward the top plate 11a.

  Next, sodium bicarbonate is introduced from the upper end of the additive introduction tube 20 with a scoop or the like. At this time, the lower end of the additive charging pipe 20 extends downward from the water surface W, and the lower end is inserted deeper than the rocking region of the water surface W due to the bubbles B. However, it does not appear on the water surface W, and the exhaust gas on the water surface W hardly enters the additive charging pipe 20. In addition, since the additive charging tube 20 is disposed avoiding the bubble region A, it is not difficult to input the additive due to the influence of the bubble B. For this reason, since an additive does not scatter when throwing in an additive, even if it does not stop the underwater combustion type vaporizer 1 like before, an additive can be thrown safely and reliably.

  And since the lower end is inserted in the area | region where the downward flow C in the water tank 11 generate | occur | produces, the additive addition pipe | tube 20 is rapidly stirred in the water tank 11 along the downward flow C. . In addition, since the lower end of the additive charging pipe 20 is disposed above the small hole 15a of the sparge pipe 15, the additive charged in the region where the downward flow C in the water tank 11 is generated rises in the bubble region. Efficiently spread on the stream.

  Therefore, according to the underwater combustion vaporizer 1 according to the present embodiment, it is possible to safely and reliably add the additive made of the powder material even during operation. In addition, the additive charging tube 20 having such a simple structure is low in cost and can be retrofitted onto the top plate 11a.

(Other embodiments)
The present invention may be configured as follows with respect to the above embodiment.

  That is, in the above embodiment, the additive is a powdered sodium bicarbonate that is easily available and relatively safe, but may be an alkaline agent such as powdered sodium hydroxide or sodium sulfate. An agent or the like may be used. However, in the case of liquid, a dedicated tank may be provided on the top plate 11a. Furthermore, the additive is not limited to a neutralizing agent, and is not particularly limited, such as a preservative and a bactericidal agent for improving water pollution.

  In the above embodiment, the additive charging pipe 20 is provided so as to be substantially vertical. However, the additive charging pipe 20 may be inclined, or may be inclined or curved in the middle. It is desirable to set the position of the part as in the above embodiment.

  Further, the additive charging pipe 20 may be provided by processing the existing top plate 11 a, and the additive charging pipe 20 may be attached to the lid of the manhole 23. When provided on the lid, a light pipe material or the like may be used so that it can be easily removed.

  Further, a measuring instrument may be provided so that the pH in the water tank 11 can be constantly monitored, or an alarm device for sounding an alarm when the pH falls below a predetermined pH. If it does so, pH control in the water tank 11 will become easy.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or a use.

  As described above, the present invention is useful for an underwater combustion type vaporizer that vaporizes a low-temperature liquefied gas such as liquefied natural gas.

1 Underwater combustion type vaporizer
2 Burner
6 Fuel supply pipe
11 Water tank
11a Top plate
12 Heat exchanger
12a Heat transfer tube
12b LNG introduction tube
12c NG discharge pipe
13 Downcomer
14 Blower
15 Sparge pipe
15a small hole
16 stacks
20 Additive feeding tube
21 Lid member
22 Flange
23 Manhole

Claims (5)

It is provided in the downcommer immersed in the water tank, burns the air supplied from the blower and the fuel supplied from the fuel supply source, and jets the combustion gas into the water through a small hole provided in the sparge pipe. A burner configured to generate air bubbles,
An underwater combustion type vaporizer having a heat transfer tube bundle immersed in the water tank and a heat exchanger configured to vaporize a low-temperature liquefied gas passing through the heat transfer tube bundle, ,
The underwater combustion type vaporizer characterized by the above-mentioned water tank being provided with the additive injection | throwing-in pipe | tube with which a lower end extends below at least the water surface and injects an additive into the said water from an upper end side. The underwater combustion vaporizer according to claim 1,
The underwater combustion type vaporizer characterized in that the additive charging pipe is arranged avoiding a bubble region where the bubbles of the combustion gas are generated. The underwater combustion vaporizer according to claim 2,
The underwater combustion type vaporizer characterized by the above-mentioned additive injection pipe being inserted deeper than the rocking | fluctuation area | region of the water surface by the said bubble. The underwater combustion type vaporizer according to any one of claims 1 to 3,
The additive charging pipe is an underwater combustion type vaporizer characterized in that a lower end is inserted in a region where a downward flow is generated in the water tank. The underwater combustion type vaporizer according to any one of claims 1 to 4,
The underwater combustion type vaporizer characterized by the above-mentioned. The lower end of the said additive injection pipe is arrange | positioned above the small hole of the said sparge pipe.

Images