KR20140091286A - Circulating Fluidized Bed Boiler - Google Patents

Abstract

Disclosed is a circulating fluidized bed boiler with a separator which can show a high separation performance without the danger of damage and which can be easily manufactured at low costs. The circulating fluidized bed boiler according to the present invention has the separator separating solid particles from flue gas after receiving the solid particles and the flue gas from a combustion furnace, wherein the flue gas is generated by the combustion of fuel. The separator includes a main body receiving the flue gas and the solid particles from the combustion furnace, wherein the main body has: multiple planar panels respectively having multiple tubes in which a heat exchange medium can flow; and multiple curved intermediate units respectively arranged between the planar panels.

Description

{Circulating Fluidized Bed Boiler}

The present invention relates to a circulating fluidized bed boiler, and more particularly, to a circulating fluidized bed boiler including a separator that can be easily manufactured at low cost while exhibiting excellent separation performance without risk of damage.

Fluidized bed combustion is a method in which a solid fuel such as a fossil fuel, a biomass fuel, etc. is combusted while flowing in a furnace together with a bed material such as sand and / or ash.

By injecting the fluidizing gas into the combustion furnace, the solid fuel and the layer material are fluidized and mixed uniformly and rapidly throughout the combustion furnace. This fluidized solid fuel and layer material is burned to produce a hot combustion gas. The combustion gas thus generated is discharged from the combustion furnace together with the heated air. A mixture of the heated air and the hot combustion gas discharged from the combustion furnace (hereinafter referred to as "flue gas") is used to generate steam for driving the steam turbine.

Typically, heat exchange in a fluidized bed boiler is accomplished in a convection section through which both the furnace and the hot exhaust gas pass. The walls of the furnace include tubes joined together by fins, and liquid flowing through the tubes absorbs heat generated in the furnace.

The fluidized bed combustion method has an advantage that the combustion reaction is fast and the operating temperature is relatively low as compared with the general thermal power combustion method, so that the amount of nitrogen oxide generated is small.

The circulating fluidized bed combustion system is a method in which solid particles discharged from a combustion furnace together with an exhaust gas are separated from the exhaust gas and returned to the combustion furnace.

Generally, the circulating fluidized bed boiler includes a combustion furnace, a separator connected to an outlet formed in the upper part of the furnace, and a return duct for circulation of the solid particles separated from the exhaust gas in the separator. The return duct is in fluid communication with the combustion furnace through an inlet formed in a lower portion of the combustion furnace. The separator and the return duct constitute a particle circulation system.

A typical separator is a centrifuge called a cyclone, which includes a cylindrical cylinder and a conical bottom. Unlike a combustion furnace of a cooling structure including a plurality of tubes through which heat exchange medium can flow, the conventional cyclone has an uncooled structure made only of a refractory material. When the separator of the uncooled structure is connected to the combustion furnace of the cooling structure, the separator is liable to be damaged, and since the separator must be designed in consideration of a change in thermal motion of the exhaust gas and the solid particles, It costs money.

In order to solve the above problems, a cylindrical cyclone including a plurality of tubes through which a heat exchange medium can flow has been proposed. However, since the plurality of tubes joined together by the fins have a flat shape, connecting a cylindrical cyclone including a plurality of tubes to the furnace requires a lot of labor, It costs a lot.

Alternatively, a polygonal cyclone comprising a plurality of tubes may be considered. The polygonal cylinder can be manufactured relatively easily by forming a flat panel and combining the flat panels with each other by a plurality of tubes joined together by the fins.

However, the principle in which the exhaust gas and the solid particles are separated from each other in the cylinder (the exhaust gas introduced into the cylinder forms a vertical vortex, the solid particles mixed into the cylinder are discharged to the inner wall of the cylinder by the centrifugal force, Is raised from the cylinder through the upper exhaust duct while rising upward), the polygonal shape of the cylinder, particularly the corner portion where the flat panels form an angle, interferes with the formation of swirl of the exhaust gas in the cylinder.

In addition, in order to guide the solid particles falling along the inner wall of the cylinder to the return duct, the lower part of the cyclone must have a gradient shape. When the polygonal cyclone is manufactured by combining the flat panels, Of the cyclone.

Accordingly, the present invention is directed to a circulating fluidized bed boiler that can avoid problems due to limitations and disadvantages of the related art.

One aspect of the present invention is to provide a circulating fluidized bed boiler including a separator that can be easily manufactured at low cost while exhibiting excellent separation performance without risk of damage.

Other features and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description. Alternatively, other features and advantages of the present invention may be understood through practice of the present invention. Objects and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims of this invention.

According to one aspect of the present invention as described above, a combustion furnace in which fuel is fluidized and combusted;

A separator for separating the solid particles from the flue gas from flue gas and solid particles generated by the combustion of the fuel; And a return system for returning the solid particles separated from the flue gas to the furnace by the separator, wherein the separator comprises a main body from which the solid particles are separated from the flue gas, A plurality of planar panels each including a plurality of tubes through which the media may flow; And a plurality of curved intermediate units each disposed between the plurality of flat panels.

Each of the plurality of joints may have a shape of a pipe having a fluid circulation passage therein.

Each of the plurality of flat panels comprising: a first common tube; A second common conduit; And a plurality of pins connecting the plurality of tubes to each other, wherein each of the plurality of tubes is in fluid communication with the first and second common tubes through both ends thereof.

Each of the plurality of flat panels further includes a lining surrounding the plurality of tubes, and the curved joints may be formed of the same refractory material as the lining.

Wherein the separator further comprises a lower portion for guiding the solid particles separated from the flue-gas to the return system in the main body, the lower portion having a circular cross-section and a gradually decreasing gradient shape toward the return system, It may be a non-cooled structure without a tube through which the medium may flow.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are intended to provide further explanation of the invention as claimed.

According to the present invention, it is possible to stably and accurately separate the solid particles from the exhaust gas discharged from the combustion furnace, and to easily manufacture the separator with a minimized risk of damage at low cost.

The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, and, together with the description, serve to explain the principles of the invention.
FIG. 1 schematically shows a vertical section of a circulating fluidized bed boiler according to an embodiment of the present invention,
Figure 2 schematically shows a front view of a separator according to one embodiment of the present invention,
3 is a horizontal sectional view along line II 'of FIG.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Therefore, the present invention encompasses all changes and modifications that come within the scope of the invention as defined in the appended claims and equivalents thereof.

As used herein, the term " horizontal section " means a section perpendicular to the direction of gravity.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows a vertical section of a circulating fluidized bed boiler according to an embodiment of the present invention.

As illustrated in FIG. 1, the circulating fluidized bed boiler of the present invention includes a combustion furnace 100 and a particle circulation system 200.

The furnace 100 includes a front wall 110a, a rear wall 110b, and two side walls located therebetween. The furnace 100 is closed by a roof 110c and a bottom 110d located at the top and bottom, respectively.

The combustion furnace 100 further includes a plate 120 extending on the bottom 110d in parallel with the bottom 110a. A plurality of holes are formed in the plate 120, and a plurality of nozzles 130 corresponding to the holes are mounted on the plate 120. A space between the plate 120 and the bottom 110a constitutes a gas chamber 140 and a fluidizing gas is supplied from an external gas supply source (not shown) to the gas chamber 140. [

A solid fuel such as fossil fuel, biomass fuel or the like is supplied into the combustion furnace 100 through the fuel supply unit 150. A specific adsorbent such as limestone or the like may be injected into the combustion furnace 100 in addition to the solid fuel. The adsorbent may be injected into the combustion furnace 100 through the fuel supply unit 150 together with the solid fuel or may be injected into the combustion furnace 100 separately from the solid fuel through another independent passage.

 The solid fuel and the adsorbent injected into the combustion furnace 100 are fluidized by the gas ejected from the nozzles 130 under the combustion furnace 100. Combustion of the solid fuel is started by a burner (not shown), and the fluidized gas further promotes combustion of the solid fuel.

A mixture of the combustion gas generated by the combustion of the solid fuel and the air heated by the combustion (hereinafter referred to as "exhaust gas") rises upward in the combustion furnace 100 by convection, Captures a part of the solid particles including the adsorbent and is discharged together with them through the combustion furnace 100 through an outlet formed in the upper part of the furnace 100, for example, the rear wall 110b.

The walls 110a and 110b of the furnace 100 include tubes coupled to each other by fins and heat exchange is performed between the liquid flowing through the tubes and the exhaust gas in the furnace 100. [

Meanwhile, the solid particles among the exhaust gas and the solid particles discharged from the combustion furnace 100 are returned to the combustion furnace 100 through the particle circulation system 200.

1, the particle circulation system 200 of the present invention includes a separator 2000 for separating the solid particles from the flue gas by receiving flue gas and solid particles discharged out of the furnace 100, And a return system (220) for returning the solid particles separated from the exhaust gas to the combustion furnace (100).

The separator 2000 is connected to the combustion furnace 100 through a duct 210. The duct 210 extends from an outlet of the furnace 100 to an inlet of the separator 2000.

The exhaust gas and the solid particles introduced into the separator 2000 from the combustion furnace 100 through the duct 210 are separated from each other by the centrifugal force in the separator 2000.

The separated flue gas is supplied to the heat recovery unit and / or the gas turbine side through the exhaust duct 300 located directly above the separator 2000.

The solid particles separated from the exhaust gas by the separator 200 fall down by gravity and enter the return system 220.

Although not shown, the return system 220 includes a return duct for receiving the solid particles from the separator 2000, a heat exchange unit for recovering heat from the solid particles supplied from the separator 2000 through the return duct, And a return unit for returning the solid particles that have been deprived of heat (i.e., cooled) to the combustion furnace 100 by the heat exchange unit.

The return system 220 includes a loop seal structure for preventing solid particles and / or gas from flowing from the combustion furnace 100 to the separator 2000 through the return system 220 can do.

Hereinafter, the separator 2000 of the present invention will be described in more detail with reference to FIGS. 2 and 3. FIG.

FIG. 2 schematically shows a front view of a separator according to an embodiment of the present invention, and FIG. 3 is a horizontal sectional view taken along the line I-I 'of FIG.

As illustrated in FIG. 2, the separator 2000 of the present invention includes a main body 2100 and a lower portion 2200.

Flue gas and solid particles flow into the main body 2100 from the combustion furnace 100 through the duct 210. The exhaust gas flowing into the main body 2100 forms a vertical vortex and the solid particles incorporated therein fall down along the inner wall by gravity toward the inner wall of the main body 2100 by centrifugal force, And is discharged from the main body 2100 through an exhaust duct provided on the upper portion of the main body 2100. [ That is, the main body 2100 of the separator 2000 is a place where the solid particles are separated from the exhaust gas.

The main body 2100 of the present invention includes a plurality of flat panels 2110 each including a plurality of tubes 2111 through which a heat exchange medium can flow, And a plurality of curved joints 2120 disposed between the flat panels 2110 of the flat panel.

According to the present invention, since the plurality of flat panels 2110 are only indirectly coupled to each other by the plurality of curved joints 2120, the inner surface of the main body 2100 is directly coupled with the plane As shown in Fig.

In other words, since the main body 2100 of the present invention does not include angled corners formed when the flat panels 2110 are directly coupled, the exhaust gas flowing into the main body 2100 forms a vortex The solid particles can be smoothly separated from the exhaust gas while sufficient centrifugal force is generated as a result.

Each of the plurality of flat panels 2110 includes a first common tube 2112, a second common tube 2113 and a plurality of fins 2114 connecting the plurality of tubes 2111 to one another , Each of the plurality of tubes 2111 may be in fluid communication with the first and second common tubes 2112 and 2113 through both ends thereof.

Alternatively, as illustrated in FIG. 3, each of the plurality of flat panels 2110 may further include a lining 2115 surrounding the plurality of tubes 2111.

The heat exchange medium or the cooling medium (for example, water) flows through the plurality of tubes 2111 so that the heated flat panels 2110 can be cooled due to the inflow of exhaust gas and solid particles. If the curvilinear joints 2120 of the main body 2100 maintain a relatively high temperature, i.e., the flat panels 2110 and the curved joints 2120, despite the cooling of the flat panels 2110, The main body 2100 may be damaged due to a difference in thermal expansion.

3, each of the curved joints 2120, which mediate the engagement of the flat panels 2110, has a fluid circulation passage P inside thereof, as shown in FIG. It can have a pipe shape.

According to an embodiment of the present invention, the pipe-shaped bending joints 2120 are connected to the first and second common pipes 2112 and 2113 of the flat panels 2110 via both ends thereof, do. Alternatively, each of the curved joints 2120 having a pipe shape may have independent inlet and outlet ports.

The temperature change behavior of the flat panels 2110 and the curved joints 2120 can be made similar by flowing a heat exchange medium or a cooling medium such as water through the fluid circulation path P of the curved joints 2120 have.

The curved joints 2120 may be formed of the same material as the lining 2115 of the flat panels 2110 to minimize the difference in thermal expansion between the flat panels 2110 and the curved joints 2120. [ .

A heat exchange medium or a cooling medium (for example, water) flows through the tubes 2111 of the flat panels 2110 and the fluid circulation passage P of the curved joints 2120, The entire main body 2100 heated by the inflow can be cooled.

Therefore, according to the present invention, since the main body 2100 of the separator 2000 as well as the combustion furnace 100 also has a cooling structure, the exhaust gas and the solid particles are discharged from the combustion furnace 100 to the main body The thermal motion change can be minimized when moving to the heat exchanger 2100 so that the separator 2000 can be manufactured easily and at low cost without substantial consideration of such thermal motion variations.

In addition, according to the present invention, the flat panels 2110 including the plurality of tubes 2111 coupled by the fins 2114 are not bent or bent forcibly, and the main body 2100 ), The separator 2000 can be manufactured at a relatively low labor and relatively low cost as compared with a cylindrical cyclone.

3, the main body 2100 includes four flat panels 2110 which are indirectly coupled to each other through the curved joints 2120. However, in the present embodiment, The invention is not limited thereto.

According to other embodiments of the present invention, as the number of the flat panels 2110 and the curved joints 2120 increases, the main body 2100 may have a generally curved inner surface, The body 2100 includes six or eight flat panels 2110 that are indirectly coupled to each other via the curved joints 2120.

As described above, since the main body 2100 of the present invention does not include angled corners formed when the flat panels 2110 are directly coupled, the exhaust gas flowing into the main body 2100 So that the solid particles can be smoothly separated from the exhaust gas while generating sufficient centrifugal force.

The lower part 2200 of the separator 2000 of the present invention is located below the main body 2100 and guides the solid particles separated from the exhaust gas from the main body 2100 to the return system 220.

The lower portion 2200 has a circular horizontal cross-section as illustrated in FIG. 2, has a gradient shape gradually becoming narrower toward the return system 220, and can be made of a refractory material such as a ceramic material or the like.

According to an embodiment of the present invention, the lower portion 2200 of the separator 2000 is an uncooled structure that does not include a tube through which the heat exchange medium can flow, and is sealed under the main body 2100 of the separator 2000 Gas-tightly.

According to the present invention as described above, the separator 2000, which can stably and accurately separate the solid particles from the exhaust gas discharged from the combustion furnace 100 and minimizes the risk of damage, can be easily manufactured at low cost.

100: combustion furnace 200: particle circulation system
210: duct 220: return system
300: exhaust duct 2000: separator
2100: main body 2110: flat panel
2111: tubes 2112, 2113: first and second common pipes
2114: pin 2115: lining
2120: curved joint portion 2200:

Claims (5)

A combustion furnace in which fuel is fluidized and combusted;
A separator for separating the solid particles from the flue gas from flue gas and solid particles generated by the combustion of the fuel; And
And a return system for returning the solid particles separated from the exhaust gas to the furnace by the separator,
The separator comprising a main body from which the solid particles are separated from the exhaust gas,
The main body includes:
A plurality of planar panels each including a plurality of tubes through which the heat exchange medium may flow; And
And a plurality of curved intermediate units each disposed between the plurality of flat panels. The method according to claim 1,
Wherein each of the plurality of joints has a shape of a pipe having a fluid circulation passage therein. The method according to claim 1,
Each of the plurality of flat panels comprising:
A first common pipe;
A second common conduit; And
And a plurality of pins connecting the plurality of tubes to each other,
Wherein each of the plurality of tubes is in fluid communication with the first and second common tubes through both ends thereof. The method according to claim 1,
Each of the plurality of flat panels further comprising a lining surrounding the plurality of tubes,
Wherein the curved joints are formed of the same refractory material as the lining. The method according to claim 1,
The separator further comprises a lower portion for guiding the solid particles separated from the flue gas to the return system in the main body,
Wherein the lower portion has a circular horizontal cross section and has a gradient shape gradually becoming narrower toward the return system and is an uncooled structure without a tube through which the heat exchange medium can flow.

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