JPH042843B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a steam generator, and more particularly to a steam generator that is substantially sulfur-free and is produced by a gasifier arranged integrally with the steam generator. The present invention relates to a device for burning generated gas with a low calorific value.

BACKGROUND OF THE INVENTION The Environmental Protection Agency and various national agencies have established codes of practice that specify maximum allowable sulfur oxide emission levels for power plants that use fossil fuels. In accordance with these standards, gas purification equipment from the stack has been designed to remove or scrub sulfur oxides from the steam generator stream gas before release to the atmosphere. There is. Since a large amount of gas with a dilute sulfur oxide concentration is concentrated at the outlet of the steam generator, the stack gas purification equipment is large and expensive. Instead of controlling sulfur oxide emissions by treating the stack gas, it is preferred to remove sulfur from the fuel prior to combustion in the steam generator. This is because the volume of gas to be treated is extremely small at this stage. For this purpose, a gasification process has been developed which involves the partial combustion of a fuel, such as particulate lime or heavy oil, in a fluidized bed of limestone particles. Desulfurization is carried out via reaction with limestone particles, producing a flammable off-gas which is introduced into a steam generator with a commercially available gas burner and combusted.

However, in the case of particulate lime, these systems require hot gas ducts to be provided along the cyclone separator to pass the product gas from the gasifier to the steam generator. However, this equipment is expensive and, in addition, the insufficient efficiency of the cyclone separator allows lime particles to enter the furnace, resulting in significant carbon build-up. Therefore, gasification equipment must be designed to burn the carbon, which inevitably reduces the efficiency of the equipment.

OBJECTS OF THE INVENTION It is therefore an object of the invention to provide a steam generator in which sulfur is removed from the fuel prior to combustion within the steam generator.

It is a further object of the invention to provide a device of the above type in which a chemically active fluidized bed is provided which generates a substantially sulfur-free product gas which is passed to the steam generator.

It is a further object of the invention to provide a device of the above type in which a sulfur-free gas is generated in a gasification device and passed to a steam generation device without the use of ducts or cyclone separation devices.

It is a further object of the invention to provide a device of the above-mentioned type in which a two-stage combustion with removal of sulfur in the gasification device and fuel combustion of the gas with carbon particles in the furnace is achieved. be.

Furthermore, it is an object of the invention to provide a device of the above-mentioned type in which the gasification device is formed integrally with the steam generator and is supported in a similar manner to the steam generator.

Furthermore, it is an object of the invention to provide a device of the above-mentioned type, in which a plurality of gasification devices are provided on one side of the vertical wall of the furnace section of the steam generator.

Arrangements of the Invention To achieve these objects, the apparatus of the invention comprises a steam generator comprising a vertical furnace section. Each of the plurality of gasification devices includes one adjacent wall, each wall supporting a layer of sulfur adsorbent resulting from combustion of the fuel introduced into the layer. Air is passed through the bed of adsorbent to fluidize the adsorbent so that a substantially sulfur-free product gas is produced when the fuel is combusted. The gasification device communicates with the interior of the furnace section, resulting in
The product gas from the gasification device is passed through a furnace section and combusted.

DESCRIPTION OF THE EMBODIMENTS The foregoing description and further objects, features and advantages of the present invention can be more fully understood by reference to the following detailed description of preferred embodiments of the invention accompanied by the drawings. I am convinced.

Referring specifically to FIG. 1, the steam generator 10 used in the present invention includes a lower furnace section 12, an intermediate furnace section 14, and an upper furnace section 16. The boundary wall forming the furnace parts 12, 14, 16 is the front wall 1
8, a rear wall 20 and two side walls extending between the front wall and the rear wall, one of the side walls;
One is indicated by reference number 21.

Walls 18, 20 and 21, shown schematically for convenience, are formed from a plurality of tubes having continuous fins extending outwardly from diametrically opposite sides, the fins of adjacent tubes being welded together by any known method, such as welding. It should be understood that a gas-tight structure is formed by the above.

The lower portions of the front wall 18 and the rear wall 20 are slanted inwardly from the intermediate furnace section 14, as shown at 18a and 20a, respectively, so that the lower furnace section 12 forms a hopper. are doing.

Four gasification devices 22, 2 integrally formed
4, 26 and 28 are located on the side of generator 10 adjacent front wall 18. Gasification device 2
2, 24, 26 and 28 are vertical wall portions 30, 3
2, 34 and 36, respectively, the vertical wall portions of which extend in parallel spaced relation to the front wall 18 to form a chamber 38. The chamber 38 communicates with a plurality of refractory alignment holes 40 formed along the lower portion of the front wall. A plurality of nozzles 42 are connected to front wall 18 and wall portion 30.
and 32, with the jet end of each nozzle extending into a corresponding opening 40.

The preheater 46 is in heat exchange relationship with a duct 48 that receives air from an external source and is connected to devices 22, 24, 26 and 28 for gasifying the preheated air.
is fed to a wind box 50 surrounding the air. These gasification devices are vertically spaced;
This allows preheated air from the windbox 50 to enter each gasifier via the grate forming the floor of the gasifier, as will be described below. A set of dampers 51 is provided within the duct 48 to control the air flow into the duct, through the wind box 50, and into the gasifiers 22, 24, 26 and 28, as shown by the solid arrows. It's summery. Details of the construction and operation of the gasification devices 22, 24, 26, and 28 will be described later.

The duct 52 branches from the duct 48 to form the duct 4.
Steam generator windbox support structure 4 in such a way that a portion of the air from 8 can be directed into and through opening 40 in front wall 18.
Connected to 4.

A set of dampers 53 is provided within the duct 52 and is adapted to control the air flow through the duct.

Heat recovery region 54 is located adjacent upper furnace section 16 in gas flow communication therewith and includes a vestibule section 56 and a convection section 58 .

The convection section 58 includes a front wall 60, a rear wall 62 and 2
It has two side walls 64, one of which is shown in FIG. The rear wall 62, side walls 64, and lower portions of the front wall 60 all consist of a plurality of interconnected vertically extending tubes with fins in a manner similar to the furnace section, with screen openings in the wall 60. It will be appreciated that the screen opening in the upper portion is adapted to allow communication between the vestibule portion 56 and the convection portion 58.

A partition wall 66 formed by a plurality of interconnected finned tubes is also provided within the convection section 58 and separates the convection section 58 into a front gas passage 68 and a rear gas passage 70. It is divided into An economizer 72 is located at the bottom of the rear gas passage 70, and a primary superheater 74 is located immediately above the economizer 72. A front gas passage 68 is provided with a set of reheat tubes.

A platen superheater 78 is provided in the upper furnace section 16 and a final superheater 79 is provided in the vestibule section 56 in direct fluid communication with the platen superheater 78.

A plurality of dividing walls, one of which is designated by the reference numeral 80, extends into the upper furnace section 16;
Each wall is formed by a plurality of interconnected tubes. Each dividing wall 80 is connected to the rear wall 2 as shown.
0 and extends upward to form the upper furnace section 1.
It has reached the inside of 6.

Roof 82 is disposed on top of steam generator 10 and consists of a plurality of tubes extending horizontally across steam generator 10 with fins connected in the manner described above. The roof 82 is supported at the top by a plurality of support members 84 to an upper support structure (not shown) and is connected to the steam generator 1 as shown.
0 and the entire structure, including the gasifiers 22, 24, 26 and 28, is adapted to allow downward thermal expansion.

Gasification device 22 is shown in detail in FIGS. 2 and 3, and other gasification devices 24, 26
and 28 are all constructed and arranged in the same manner. Gasification apparatus 22 includes a gasification section 86 and a regeneration section 88 separated by a vertical wall 90 extending in spaced parallel relation to wall 30 . The grid 94 is the gasification device 22
and is adapted to accommodate a plurality of T-shaped air distribution pipe assemblies 96 for receiving air from the windbox 50 and introducing the air to the gasification section 86 and the regeneration section 88. . As shown in detail in FIG. 3, each pipe assembly 96 includes vertical pipes 96a extending through openings in the grid 94.
and a horizontal pipe 96b aligned and connected to the vertical pipe.

A particle coal feeder 98 (FIG. 1) is supported on the front vertical wall of each gasifier 22, 24, 26, and 28 and continuously supplies particle coal onto the fluidized bed of each gasifier. It is starting to be put into use. Additionally, multiple oil distribution pipe assemblies (not shown) may extend through other openings in the grate 94 below the gasification section 86, with each assembly leading to a gasification device. connected to a source of oil.

A supply device 100 extends through the side wall of gasification device 22 and is adapted to supply adsorbent, such as limestone, to gasification section 86 .

A dividing wall 102 is disposed in the gasification section 86 and divides the gasification section 86 into chambers 86a and 86b (FIG. 3). The dividing wall 102 extends from the partition 90 (FIG. 2) to an area spaced apart in the opposite direction from the regeneration portion 88 and communicates the chambers 86a and 86b with a passageway 86c (FIG. 2).
is formed.

An inlet slot 106 and an outlet slot 108 are formed in the partition wall 90, with the inlet slot 10
6 connects the gasification chamber 86a to the regeneration section 88, and the outlet slot 108 connects the gasification chamber 86a to the regeneration section 88.
b is communicated with the reproduction section 88.

As a result of this configuration, the mixture of limestone and fuel is routed from gasification chamber 86b through passage 86c.
It flows continuously through gasification chamber 86a and slot 106 into regeneration section 88, and from the regeneration section 88 through slot 108 into gasification chamber 86b for circulation.

A discharge manifold 110 communicates with the top of the regeneration section 88 and discharges sulfur gas generated in the regeneration section to an external sulfur recovery device (not shown). For this purpose each gasifier 22, 24,
Manifolds 110 from 26 and 28 are connected as shown in phantom in FIG. 1 and constitute a single source of sulfur gas.

Since gasifiers 24, 26 and 28 are constructed and operated in the same manner as gasifier 22,
I will not discuss them in detail. In this connection, the horizontal and vertical wall sections forming the gasification devices 22, 24, 26 and 28 are water-cooled as in the case of the other walls mentioned above, i.e. the horizontal and vertical wall sections mentioned above are Note that the water pipes are formed by interconnected finned water pipes.

In operation, the gasification devices 22, 24, 26
and the temperature of each fluidized bed in the gasification section 86 of 28 is:
By controlling the fuel entering those layers, a predetermined temperature rise value (eg, 1600° C.) is maintained. Air from the windbox 50 is passed through the preparator 46 and duct 48 and is introduced into the gasification section of each gasification unit via an air distribution pipe assembly in approximately stoichiometric proportions to reduce combustion and heat production. Restrict.

Partial combustion of the fuel entering gasification section 86 with approximately 25% to 30% stoichiometric air provides sufficient heat to partially combust the fuel. If petroleum is used, this heat will evaporate and decompose the remaining petroleum. This partial combustion forms hydrogen sulfide, which reacts with the fluidized bed of limestone to produce calcium sulfide and water vapor. The gasification product of this step is a substantially sulfur-free and vanadium-free fuel gas that rises into the gasification section 86 and then passes through the adjacent walls 30, 32, 30 as indicated by the dashed arrows in FIG. and exits the gasification section via the space formed between 36 and 36. The gas then enters chamber 38 and passes through nozzle 42 . Secondary air from duct 52 enters opening 40 to cause complete combustion of the gas within intermediate furnace section 14 in the usual manner. Gasification part 86
The sulfur retention capacity of is maintained by continuously removing sulfated limestone and replenishing sulfur-free limestone-containing material through feeder 100. The sulfated limestone with spent fuel particles is discharged from each gasifier 22, 24, 26 and 28 in a conventional manner, such as by drain pipes (not shown).

Air from the windbox 50 is also introduced into the regeneration section via pipe assembly 96 and the calcium sulfide formed in the gasification section 86 is circulated through the regeneration section 88 as described above, where the calcium sulfide is concentrated It changes to calcium oxide while producing off-gas containing sulfur dioxide. When the calcium sulfide is transferred to the oxygen-rich regeneration section 99, preferably at about 1900°C (1038°C), the following reactions occur.

CaSO ₄ +CaS+O ₂ →2CaO+2SO ₂ The sulfur dioxide produced in the above reaction passes through each discharge manifold 110 to gasification devices 22, 24, 2.
6 and 28, combined as described above, and recovered from the gas stream by external equipment in the form of elemental sulfur. On the other hand, calcium oxide is stored in the gasification section 86 for reuse as a sulfur adsorbent.
will be returned to.

Referring again to FIG. 1, the gasification device 22,
Combustion gases produced as a result of combustion in the middle furnace section 14 of sulfur-free gases from 24, 26, and 28 are passed upward to the upper furnace section 16 and into the front gas passage 68 and the rear gas passage 70. It passes through a heat recovery area 54 before exiting. As a result, the hot gas passes through preheater 76 and economizer 72 as well as platen superheater 78 and final superheater 79, heating the fluid flowing through these circuits. The hot gas then passes through air preheater 46 to preheat the air entering duct 48.

Although not explicitly shown in the drawings, suitable inlet and outlet headers, downcomers and conduits are provided to provide fluid access to the roof as well as to each of the aforementioned walls and heat exchanger tubes. A circulation path is formed in which the incoming water is heated to steam. For this purpose, feed water from an external source passes through an economizer 72 to increase the water temperature before passing from the walls of the gasifiers 22, 24, 26 and 28 through said walls to the dividing wall 80. The superheated water is directed from the gasifier wall to an inlet header (not shown) located at the bottom of the furnace walls 18, 20, and 21, with all water passing through the walls 18, 20, and 21. It continues to flow upwards, and if the critical point is below, the temperature increases further, and if the critical point is exceeded, at least water Some of it turns into steam.
The fluid then descends through appropriate downcomers, passes through a heat recovery area, and then collects and passes through the roof. Fluid from the roof 82 is directed to a separation device (not shown) via a suitable collection header or the like. The separation device separates the vapor portion of the fluid from its liquid portion upon start-up. The liquid portion is directed from the separator to a drain manifold and a heat recovery circuit (not shown) for further processing, and the vapor portion of the fluid within the separator is directed directly to the primary superheater 74. The fluid from this superheater 74 is kept warm in a sprayed state and then led to a platen superheater 78 and a final superheater 79, and then passed through a turbine etc. in a dry steam state. After start-up, the separating device acts merely as a transfer header.

It should be understood that the arrangement of the invention is equally applicable to natural circulation systems using steam drums in a conventional manner.

From the above, a sulfur-free product is produced which is introduced directly into the steam generator. In this case, duct piping and cyclone separation equipment for hot gases are not required. Additionally, the furnace can be designed to accept and burn a certain amount of carbon solid particles entrained in the gas exiting the gasifier, thereby eliminating the need to burn this carbon within the gasifier. disappears.

The foregoing disclosure contemplates the freedom to modify, change, and substitute, and in certain instances, certain features of the invention may be used without the use of other features. Accordingly, the claims should be interpreted broadly and in accordance with the spirit of the invention.

In the present invention, since the plurality of gasification devices are arranged in the vertical direction, the steam generation is A large number of gasification devices can be arranged per unit floor area of the device. This makes it possible to avoid increasing the size of the steam generator due to the use of a plurality of gasification devices.

Furthermore, when a plurality of gasification devices are arranged in a plane, a nozzle and an alignment hole are required for each gasification device, but in the present invention in which the gasification devices are arranged in the vertical direction, A set of nozzles and alignment holes can be shared for each gasification device, and the steam generation device can be configured compactly.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the steam generation and gasification apparatus of the present invention, FIG. 2 is an enlarged cross-sectional view of a part of the apparatus shown in FIG. 1, and FIG. 3 is a line 3--3 shown in FIG. FIG. Explanation of symbols, 10...Steam generator, 12...
Lower furnace part, 14... Middle furnace part, 16... Upper furnace part, 18... Front wall, 22, 24, 26,
28... Gasification device, 50... Wind box, 52... Duct, 53... Damper, 72...
Economizer, 78...Platen superheater, 79...
... Final superheater, 88 ... Regeneration section, 96 ... Pipe assembly.

Claims (1)

[Scope of Claims] 1. A steam generator comprising a furnace section formed by four vertical walls and a plurality of openings formed in at least one of the vertical walls, the interior of each of which communicates with the opening. a plurality of gasification devices extending adjacent to said one vertical wall and surrounding said opening; means for introducing fuel into each gasification device; and means for gasifying said fuel in each gasification device; means for supporting the layer of sulfur adsorbent thus generated;
Air is passed through the layer of adsorbent to fluidize the adsorbent and generate a substantially sulfur-free product during gasification of the fuel, which product is passed from the gasification device through the opening. and introduce it into the furnace part,
A device for steam generation and gasification, comprising means for causing combustion of gas and unreacted carbon, and means for supporting the gasification device and the steam generation device at the top. 2. Apparatus according to claim 1, characterized in that each gasification apparatus includes means for producing said sulfur-containing adsorbent which generates sulfur gas. 3. The apparatus according to claim 1, wherein the fuel is coal introduced into the fluidized bed. 4. The apparatus according to claim 1, wherein the fuel is petroleum fuel injected into the fluidized bed. 5. Claim characterized in that the gasification device is spaced from one wall of the furnace section and forms a gas chamber that receives gas from the gasification device and directs the gas to the opening. The device according to item 1. 6. The invention further comprises a plurality of nozzles extending from the gas chamber to the opening, adapted to receive gas from the gasification device and introduce the gas into the furnace section. The device according to scope item 5. 7. The apparatus according to claim 1, further comprising a wind box surrounding the gasification apparatus. 8. The apparatus of claim 7 further comprising an air source and duct means for passing said air to said windbox. 9. The method of claim 8 further comprising means for causing combustion gases from the furnace section to pass in heat exchange relationship with the air before the air passes into the windbox. Apparatus described in section. 10. Claim 1, characterized in that the vertical walls of the furnace section and the walls of the gasification device are formed by a plurality of tubes containing water and heating the water to steam. The device described. 11. The device according to claim 1, wherein the gasification device is formed integrally with an adsorbent regeneration device.