JP2017138076A - Boiler and floating body facility including the same - Google Patents

Abstract

A boiler capable of incinerating an inert gas having a combustible component in a furnace. A burner for injecting boiler fuel and boiler air as a swirling jet J into a furnace 2 and a high-temperature recirculation region R formed on the side of the swirling jet J injected from the burner 3 are combustible. And a combustible component-containing inert gas supply unit 15 for supplying an inert gas having components. The combustible component-containing inert gas supply unit 15 is provided on the bottom wall 2 a facing the burner 3. [Selection] Figure 1

Description

  The present invention relates to a boiler capable of incinerating an inert gas having a combustible component, and a floating facility equipped with the same.

In recent years, floating facilities such as FPSO (Floating Production, Storage and Offloading System) are toxic and combustible in the treatment process in anticipation of strengthening environmental regulations in the next few years. Attention has been increasing for incineration of inert gases having components.
At present, since no environmental regulations have been established, flammable gases are released into the atmosphere through periodic vent discharges. In areas where environmental regulations have been established, inert gas containing flammable components is incinerated by using assist fuel or the like to be rendered harmless and released into the atmosphere.
Up to now, the floating equipment such as FPSO has been mainly used for oil, but in recent years, development of plants for LNG has been progressing. LNG uses a process such as reliquefaction because off-gas is also part of the product, and a large amount of inert gas containing a combustible component in this reliquefaction process. Active gas) may be released, and there is a need for incineration of these.
Patent Document 1 discloses a dedicated gas incinerator for incinerating an inert gas having a combustible component in a liquefied gas tanker ship or a liquefied gas terminal.

JP 2006-2000885 A

However, since a marine boiler is installed in the floating body equipment for supply of miscellaneous steam used in the ship or for power generation equipment, it is desirable to incinerate the inert gas having these combustible components in the marine boiler.
Incineration treatment of an inert gas having a combustible component in a boiler furnace has a track record in a boiler having a large furnace volume such as a land-use conventional boiler used for thermal power generation. However, it is difficult to completely incinerate toxic combustible components for a furnace having a small furnace volume such as a marine boiler because the residence time in the furnace is short.

  The present invention has been made in view of such circumstances, and incinerate inert gas having combustible components even in a boiler such as a marine boiler having a small furnace volume compared to a land-use conventional boiler. It aims at providing the boiler which can be processed, and the floating equipment provided with the same.

In order to solve the above-mentioned problems, the boiler of the present invention and the floating equipment equipped with the same employ the following means.
That is, the boiler according to the present invention has a burner that injects boiler fuel and boiler air as a swirling jet into the furnace, and a combustible component for the recirculation region formed on the side of the swirling jet injected from the burner. And a combustible component-containing inert gas supply unit for supplying the inert gas.

  From the burner, boiler fuel and boiler air are injected as a swirling jet. By this swirling jet, a recirculation region is formed in the side region. Since the recirculation zone has a slower flow velocity than the swirling jet injected from the burner, the residence time in the furnace can be increased in the recirculation zone. Therefore, an inert gas having a combustible component is supplied to the recirculation region to incinerate the inert gas having a combustible component. Thereby, since the inert gas which has the combustible component which joined the recirculation area | region can obtain the residence time in a furnace required for an incineration process, a thermal decomposition reaction can be accelerated | stimulated in a furnace.

  Furthermore, in the boiler according to the present invention, the combustible component-containing inert gas supply unit is provided on a wall portion facing the burner.

  By providing a combustible component-containing inert gas supply section on the wall facing the burner and taking a sufficient distance from the burner, the inert gas having a combustible component joins the swirling jet injected from the burner. You can avoid that. Thereby, the residence time in the furnace of the inert gas which has a combustible component is securable.

  Furthermore, the boiler of the present invention includes a superheater provided on the downstream side of the combustion gas flow of the furnace, and an evaporator provided on the downstream side of the combustion gas flow of the superheater, and the combustion gas is mixed with the superheater. A superheater bypass region heading toward the evaporator without heat exchange is formed.

In general boilers, in order for the superheater to sufficiently absorb the amount of heat of the combustion gas, the entire amount of the combustion gas is allowed to flow to the superheater, so that a superheater bypass region where the combustion gas does not exchange heat with the superheater is not provided. . On the other hand, in the present invention, a superheater bypass region is provided. In the superheater bypass region, since the combustion gas does not exchange heat with the superheater, the temperature of the combustion gas does not decrease and remains at a high temperature. Therefore, since the pyrolysis reaction of the inert gas having the combustible component proceeds while the combustion gas flows through the superheater bypass region, the incineration process of the inert gas having the combustible component can be performed more effectively.
Therefore, it is preferable that the superheater bypass region is provided in a region where the combustion gas flows in the recirculation region.

  Furthermore, in the boiler according to the present invention, the superheater bypass region is provided at a position different from a region where a main flow of a swirling jet injected from the burner flows.

  If the superheater bypass region is provided in the region where the main flow of the swirling jet injected from the burner flows, the inert gas having combustible components flowing in the recirculation region may not be guided to the superheater bypass region. There is. Therefore, it is preferable to provide the superheater bypass region at a position different from the region where the main flow of the swirling jet flows.

  Furthermore, in the boiler according to the present invention, the superheater bypass region is 10 to 30% with respect to a cross-sectional area of the flow path of the combustion gas at a position where the superheater is installed.

  The superheater bypass region is 10 to 30% with respect to the cross-sectional area of the combustion gas flow path at the position where the superheater is installed. Accordingly, the area of the superheater at this position is 70 to 90% with respect to the cross-sectional area of the combustion gas flow path. Thus, by taking a large area ratio of the superheater bypass region, it is possible to cope with a plant with a large amount of processing of the inert gas having a combustible component such as FLNG (Floating Liquefied Natural Gas).

  Moreover, the floating equipment of this invention is equipped with the boiler in any one of said.

Since the boiler is provided, it is possible to incinerate the inert gas having a combustible component in the floating equipment without newly providing a dedicated device.
Floating facilities include floating production, storage and offloading systems (FPSO).

  Inert gas with flammable components can be stably incinerated by combining the inert gas with flammable components in the high-temperature recirculation zone around the burner to obtain the necessary residence time in the furnace. .

It is the longitudinal section showing the boiler concerning a 1st embodiment of the present invention. It is the longitudinal cross-sectional view which showed the boiler which concerns on 2nd Embodiment of this invention. 2 shows the upper part of the front bank tube of FIG. 2, (a) is a front view showing a state where a large area is closed with a closing plate, and (b) is a front view showing a state where a small area is closed with a closing plate. . It is the top view which showed the furnace of FIG. It is the longitudinal cross-sectional view which showed the modification of FIG.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 shows a marine boiler (hereinafter simply referred to as “boiler”) 1 according to the present embodiment. The boiler 1 is installed in floating facilities such as FPSO (Floating Production, Storage and Offloading System).

  The boiler 1 is a two-body water tube boiler. The boiler 1 includes a plurality of burners 3 in a wind box 14 installed in the upper part of the furnace 2. In FIG. 1, one burner 3 is shown, but another burner 3 is installed in a direction perpendicular to the paper surface.

  The burner 3 burns fuel oil such as heavy oil or fuel gas such as LNG by using burner air as combustion air introduced through the air duct 13 to generate combustion gas. The burner 3 includes a swirl vane 3a, and the swirl jet J is jetted by swirling the burner air by the swirl vane 3a. As shown in FIG. 1, the swirling jet J flows from the upper side to the lower side and heads toward the front bank tube 4 located on the side that is the downstream side of the combustion gas flow.

The swirling jet J injected from the burner 3 forms a flame, and the high-temperature combustion gas generated thereby is a front bank tube 4, a superheater 5, and an evaporation tube group disposed downstream of the combustion gas flow of the furnace 2. (Evaporator) 6 is sequentially passed.
The front bank tube 4 is composed of a large number of heat transfer tubes, is provided from the bottom to the top, and is arranged in a plane so as to be orthogonal to the combustion gas flow. The front bank tube 4 connects between a header 12 provided below the furnace 2 and an upper steam drum 10.

  The superheater 5 is composed of a large number of heat transfer tubes, is provided in parallel to the front bank tube 4 from the lower part to the upper halfway position, and is disposed in a plane so as to be orthogonal to the combustion gas flow. The superheater 5 is connected to two headers 11 provided below the furnace 2. That is, saturated steam is supplied from one header 11, flows upward in each heat transfer tube, turns back at the top 5 a, and then flows downward, and then is heated to a superheated state by the combustion gas and led to the other header 11. It is burned.

  The evaporator tube group 6 is composed of a large number of heat transfer tubes, is provided in a planar shape from the lower side to the upper side in parallel to the superheater 5, and is disposed so as to be orthogonal to the combustion gas flow. The evaporator tube group 6 connects between a lower water drum 9 and an upper steam drum 10. As the water in the lower water drum 9 is heated and evaporated, the water rises upward and the steam is guided into the steam drum 10. The saturated steam in the steam drum 10 is led to the header 11 of the superheater 5 through a path (not shown) so as to be overheated.

  Combustion gas that has exchanged heat with water and steam flowing in the heat transfer tubes of the front bank tube 4, the superheater 5, and the evaporator tube group 6 is discharged from the gas outlet 8 to the outside of the boiler 1 through the outlet side gas duct 7. The

  A combustible component-containing inert gas supply unit 15 is provided below the furnace 2. A combustible component-containing inert gas supply unit 15 is supplied with an inert gas having a combustible component discharged from a floating facility in which the boiler 1 is installed. In the future, the inert gas having the combustible component will be an off-gas that is required to be incinerated by environmental regulations.

  The combustible component-containing inert gas supply unit 15 is provided on the bottom wall 2a, which is a wall facing the upper portion of the furnace 2 to which the burner 3 is attached. The combustible component-containing inert gas supply unit 15 is arranged farther (right side in FIG. 1) than the burner 3 in the horizontal direction when viewed from the side as shown in FIG. Has been. Arranged in this way, an inert gas having a combustible component is supplied to the side of the swirling jet J injected from the burner 3 and upstream of the swirling jet J. Specifically, the combustible component is contained so that the inert gas having the combustible component joins the recirculation region R formed by the swirling jet J without the inert gas having the combustible component being entrained in the swirling jet J. An inert gas having a combustible component is supplied from the inert gas supply unit 15. Therefore, the inert gas having the combustible component joined to the recirculation region R is pyrolyzed together with the high-temperature recirculation flow flowing through the recirculation region R of the flame formed by the burner 3 and incinerated.

According to this embodiment, there exist the following effects.
From the burner 3, boiler fuel and boiler air are injected as a swirling jet J. A high-temperature recirculation region R is formed in a side region of the flame formed by the swirling jet J. Since the recirculation region R has a slower flow velocity than the swirling jet J injected from the burner 3, the recirculation region R can take a longer residence time in the furnace. For example, when flowing in the swirling jet J, the residence time in the furnace is about 0.3 seconds, whereas when flowing in the recirculation region R, the residence time in the furnace is 1 to 2 seconds. The Generally, it is known that an inert gas having a toxic combustible component that needs to be incinerated is effectively incinerated by securing a holding time of 1 second or more in a high temperature region of 800 ° C. or higher. ing.
Therefore, in this embodiment, the combustible component-containing inert gas supply unit 15 that supplies an inert gas having a combustible component to be incinerated for the recirculation region R is provided. Thereby, since the inert gas which has the combustible component joined to the recirculation area | region R can obtain the residence time in a furnace required for an incineration process, the thermal decomposition reaction can be accelerated | stimulated in the furnace 2. FIG. Therefore, it is possible to avoid a risk that an inert gas having a combustible component is discharged from the gas outlet 8 into the atmosphere.

By providing a combustible component-containing inert gas supply unit 15 on the bottom wall 2a facing the burner 3 and keeping a sufficient distance from the burner 3, the swirling jet J injected from the burner 3 has a combustible component. It is possible to avoid the active gas from merging. Thereby, the residence time in the furnace of the inert gas which has a combustible component is securable.
In addition, if it is a position which can join the recirculation area | region R without joining the swirl jet J injected from the burner 3, it is not essential to provide the combustible component containing inert gas supply part 15 in the bottom wall part 2a. For example, you may provide the combustible component containing inert gas supply part 15 in the upstream side wall part 2b of the furnace 2. FIG.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
This embodiment is different from the first embodiment in that a superheater bypass region 16 that bypasses the superheater 5 is provided on the upper downstream side of the front bank tube 4, and is the same in other points. Accordingly, the same components are denoted by the same reference numerals and description thereof is omitted.

  As shown in FIG. 2, an opening 4a is formed above the front bank tube 4 so that the combustion gas flows. Thus, a superheater bypass region 16 is provided on the upper downstream side of the front bank tube 4 and above the top portion 5a of the superheater 5 so that the combustion gas flows to the evaporation pipe group 6 without exchanging heat with the superheater 5. ing. In general, as shown in FIG. 3 (a), a clogging plate 18 is installed between the heat transfer tubes above the front bank tube 4, so that the combustion gas short-passes over the superheater 5 to evaporate the tube. It does not flow to group 6. In the present embodiment, as shown in FIG. 3B, the area of the blocking plate 18 is reduced or eliminated, and the short path is positively performed by flowing the combustion gas to the superheater bypass region 16.

  With the above configuration, the combustion gas flow in the recirculation region R is guided to the superheater bypass region 16 after passing through the vortex in the recirculation region R as shown in FIG. It is burned. The combustion gas after passing through the superheater bypass region 16 is guided to the gas outlet 8 through the evaporator tube group 6. FIG. 4 shows the flow of combustion gas when the furnace 2 is viewed in plan. As shown in the figure, two swirling jets J formed by the burner 3 are formed. That is, the case where there are two burners 3 is shown. The combustion gas flowing in the recirculation region R passes through both sides of the swirling jet J and flows to the front bank tube 4 side.

According to this embodiment, there exist the following effects.
In a general boiler, the superheater 5 sufficiently absorbs the amount of heat of the combustion gas, so that the superheater bypass region 16 where the combustion gas does not exchange heat with the superheater 5 is not provided. On the other hand, in the present embodiment, the superheater bypass region 16 is provided. In the superheater bypass region 16, since the combustion gas does not exchange heat with the superheater 5, the temperature of the combustion gas is kept at a high temperature without decreasing. Accordingly, since the pyrolysis reaction of the inert gas having the combustible component proceeds while the combustion gas flows through the superheater bypass region 16, the inactive gas having the combustible component can be incinerated more effectively. .

Since the superheater bypass region 16 is provided above so as to be a region into which the combustion gas in the recirculation region R flows, the superheater can remove the inert gas having a combustible component flowing through the recirculation region R more effectively. It can lead to the bypass region 16.
In addition, if the superheater bypass area | region 16 is provided in the area | region where the main flow of the swirling jet J injected from the burner 3 flows, the inert gas which has the combustible component which flows into the recirculation area | region R will flow into a superheater bypass area | region. 16 may not be able to be led. Therefore, although it is not essential to provide the superheater bypass region 16 above the superheater 5, it is preferable to provide the superheater bypass region 16 at a position different from the region where the main flow of the swirling jet J flows.

  Further, in the case of a plant with a large amount of processing of an inert gas having a combustible component such as FLNG (Floating Liquefied Natural Gas), the superheater bypass region 16 is a combustion gas at a position where the superheater 5 is installed. It is preferable to be 10 to 30% with respect to the flow path cross-sectional area. Specifically, as shown in FIG. 5, the ratio of the height h in the superheater bypass region 16 above the superheater 5 to the height H of the front bank tube 4 is set to 10 to 30%. In this way, by increasing the area ratio of the superheater bypass region 16, even if the amount of combustible gas discharged during the FLNG process is 30% or more of the boiler combustion gas, it is greatly overheated. By forming the condenser bypass region 16 and reducing the pressure loss, the inert gas having a combustible component can be processed in the boiler 1 without significantly increasing the power of the fan that pumps the gas.

DESCRIPTION OF SYMBOLS 1 Boiler 2 Furnace 2a Bottom wall part 2b Upstream side wall part 3 Burner 4 Front bank tube 4a Opening part 5 Superheater 5a Top part 6 Evaporation pipe group (evaporator)
7 Outlet side gas duct 8 Gas outlet 9 Water drum 10 Steam drum 11 Header 12 Header 13 Air duct 14 Air box 15 Inflammable component-containing inert gas supply unit 16 Superheater bypass region 18 Blocking plate J Swirling jet R Recirculation region

Claims (6)

A burner for injecting boiler fuel and boiler air as a swirling jet into the furnace;
A combustible component-containing inert gas supply unit for supplying an inert gas having a combustible component to a recirculation region formed on a side of a swirling jet injected from the burner;
The boiler characterized by having.   The boiler according to claim 1, wherein the combustible component-containing inert gas supply unit is provided on a wall portion facing the burner. A superheater provided downstream of the combustion gas flow of the furnace;
An evaporator provided downstream of the combustion gas flow of the superheater;
With
The boiler according to claim 1, wherein a superheater bypass region is formed in which the combustion gas does not exchange heat with the superheater and travels to the evaporator.   The boiler according to claim 3, wherein the superheater bypass region is provided at a position different from a region where a main flow of the swirling jet injected from the burner flows.   The boiler according to claim 3 or 4, wherein the superheater bypass region is 10 to 30% with respect to a cross-sectional area of the flow path of the combustion gas at a position where the superheater is installed.   A floating facility comprising the boiler according to claim 1.

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