JP3286762B2 - Slurry supply conduit and pressurized fluidized bed combustion furnace - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lime / water slurry supply pipe, and more particularly, to burning coal in a pressurized fluidized bed, driving a steam turbine by generated steam, and further using a high pressure, high temperature combustion gas to produce a gas turbine. Of coal / water slurry (hereinafter sometimes simply referred to as slurry) when supplying a mixed slurry of coal and water to a combustion furnace of a pressurized fluidized-bed boiler combined cycle power plant that obtains electric power with high efficiency by driving It relates to a supply conduit.

[0002]

2. Description of the Related Art A pressurized fluidized-bed boiler (combustion furnace) can obtain energy from generated steam and high-pressure combustion gas, so that high-efficiency power generation is possible. However, one of the issues is to continuously and stably supply solid coal particles into a pressurized combustion furnace in a large amount. Conventionally, as a method of supplying coal to a fluidized bed combustion furnace, a wet supply method in which coal particles and water are mixed to form a slurry-like fluid and the slurry is pressurized and pumped by a pump and supplied from a spray nozzle (for example, 62-155433). The slurry supply method is more reliable than the dry supply method, for example, a method in which pretreatment such as drying is not required and the cost is low, and the abrasion of the transport pipe is small, as compared with a method in which the pressure is increased by a lock hopper and the air is transported. However, the amount of water added to the coal must be reduced as much as possible in order to maintain the power generation efficiency at the same level as in the dry feed system. For this reason, the amount of added water is limited, and the viscosity of the coal / water slurry is high, and the maximum particle size of the coal is as large as several mm and the fluidity is poor. When supplying the coal / water slurry having poor fluidity to the fluidized bed combustion furnace, a fixed-quantity pump such as a piston pump is used, and is sprayed from a nozzle through a conduit and supplied into the combustion furnace.

[0003] There is CWM (coal / water mixture) which has been developed as a fuel alternative to heavy oil. This is a fine particle having an average particle diameter of several tens of μm of coal, having a water content of about 35 wt%, and further adding a surfactant for decreasing the viscosity. Therefore, while the viscosity of the coal / water slurry according to the present invention is 10 to 20 Pa · s,
CWM has a very low viscosity at around 1 Pa · s.

[0004]

THE INVENTION Problems to be Solved] In the conduit for supplying coal-water slurry to the spray nozzle of the combustion furnace slurry wet feed system described above from the pump, particularly Oite conduit interconnections portions having different inner diameter, spraying the slurry If it is necessary to reduce the inner diameter of the conduit in order to reduce the diameter of the conduit arbitrarily in the same way as supplying a low-viscosity liquid such as heavy oil or CWM, the supply conduit will be clogged and the slurry cannot be supplied. There was a problem. Therefore, an object of the present invention is to provide a supply conduit for smoothly transporting a slurry such as a coal / water slurry without clogging, and to realize a more reliable pressurized fluidized bed combustion furnace.

[0005]

The present inventors have made intensive studies to solve the above-mentioned problems, and found that the reduction rate of the diameter of the conduit for smoothly transporting the coal / water slurry should be within a specific range. all right. That is, the present invention relates to a pressurized fluidized bed combustion furnace having a fuel supply conduit for supplying coal / water slurry.
In the above, the water in the slurry is 20 to 35 wt%, and
Coal / water slurry whose viscosity is 10-20 Pa · s
The throttle angle of the throttle section of the slurry supply conduit is determined by the flow rate of the slurry.
In direction, the contraction small angle of relative to the center line of the supply conduit 5
Pressurized flow with sub-coal and water slurry supply conduit
This is a moving bed combustion furnace.

[0006]

The slurry to which the present invention is applied will be described below with reference to a coal / water slurry as a fuel for a pressurized fluidized bed combustion furnace. In order to maintain the power generation efficiency equal to that of the dry supply system, the water content in the coal / water slurry is limited to a range of about 20 to 35 wt%, though it depends on the type of coal. The resulting slurry has a viscosity of 10-20 Pa · s
In addition, the maximum particle size of coal is as large as several millimeters and poor in fluidity. If such a slurry is caused to flow in a conduit whose pipe diameter is reduced to a certain angle or more, the coal particles are consolidated in the reduced cross section, and the slurry separates water and adheres. CW in the prior art
When the viscosity is low as in M, slippage occurs between the coal particles and the compaction does not occur by satisfying the continuity equation. It is considered that no slip occurs between the coal particles and the coal particles, and the coal particles stagnate and become compacted.

On the other hand, according to the present invention, the angle of reduction of the diameter of the slurry supply conduit is selected to be 5 degrees or less, preferably 3 degrees or less with respect to the center line of the conduit, so that the pipe wall and the coal particles and the coal particles can be reduced. Slip occurs between the members, and the slurry can flow without being blocked at the reduced section.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described in detail with reference to the drawings. First, a supply system of coal / water slurry to a pressurized fluidized bed combustion furnace to which this embodiment is applied is shown in FIG. The fluidized-bed combustion furnace 101 is housed in a pressurized container 104, and an air dispersion plate 105 is provided at the bottom thereof, on which a fluid medium particle 102 is filled. Pressurized air 106
Is the combustion air 107 after being supplied into the pressurized container 104.
Then, the fluidized medium particles 102 supplied through the air dispersion plate 105 into the combustion furnace 101 are fluidized to form the fluidized bed 109.

A coal / water slurry 120 stored in a slurry tank 121 is pumped into a fluidized bed combustion furnace 101 by a pump 6 through a slurry conduit 7, supplied from a slurry spray nozzle 110 into a fluidized bed 109, and burned. You. The combustion gas is discharged from the upper part of the combustion furnace 101, and the dust is removed by the cyclone 103.
8 and is introduced into a gas turbine (not shown).

The coal / water slurry 120 in the slurry tank 121 has coal particles adjusted to a predetermined particle size distribution in an upstream slurry adjusting tank (not shown), a predetermined ratio of clean water to the coal particles, and desulfurization in the furnace. After mixing and stirring with the limestone particles for use, the slurry is supplied to the slurry tank 121 through the conduit 4 and stored. The coal / water slurry 120 in the tank 121 is stirred by the stirring blade 123 rotated by the electric motor 122, so that the fluidity is maintained. The bottom of the slurry storage tank 121 is connected to the slurry pump 6 via the valve 5.

In the middle of the slurry conduit 7, there is provided a slurry circulation conduit 8 to the slurry tank 121 via the switching valve 3. A purge air supply pipe 11 for pressurized air 10 for purging the inside of the slurry spray nozzle 110 with air.
And a valve 9 is provided in the slurry conduit 7 downstream of the switching valve 3 and as close as possible to the switching valve 3. Although not shown in FIG. 2 since the details are shown in FIG. 3 described later, the spray nozzle 110 has a spray air conduit and a cooling water conduit for spraying and dispersing the slurry in the fluidized bed combustion furnace 101. Is connected.

In the above-mentioned system shown in FIG. 2, for example, the diameter of the discharge pipe 2 of the pump 6 is too large than the required diameter of the slurry pipe 7, and the diameter of the pipe is reduced at the connection between the discharge pipe 2 and the slurry pipe 7. Sometimes it is necessary to reduce with. FIG. 1 is a detailed cross-sectional view of the reduction tube 1, and shows an angle θ ₁ formed between a center line 20 connecting the centers of the slurry inlet flange 21 and the slurry outlet flange 22 and the inner wall of the reduction tube _1.
(= Reduction angle θ _{1 with} respect to the center line 20 of the reduction tube ₁ ) is 5
Degrees or less, preferably 3 degrees or less. Although the coal / water slurry is mixed in the slurry tank 121 and a regulating tank (not shown) upstream of the slurry, sometimes there is a part in a mixed state where mixing is insufficient and fluidity is poor,
From the viewpoint of ensuring sufficient reliability, it is preferable to select the reduction angle θ ₁ to be 3 degrees or less.

[0013]

[0014] While the above SL embodiment has been described the case of applying the slurry supply conduit to a pressurized fluidized bed combustion furnace, the present invention is not limited thereto, applied to the supply device of the other combustion furnace or slurry fluid it can.

[0015]

According to the present invention, for example, in supplying coal / water slurry to a combustion furnace such as a pressurized fluidized bed combustion furnace,
Since slurry supply conduits it is not necessary to produce a closure can be provided a highly reliable combustion furnace.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a reduced tube portion of a slurry supply conduit according to an embodiment of the present invention.

FIG. 2 is a supply system diagram of a coal / water slurry to a pressurized fluidized bed combustion furnace to which an embodiment of the present invention is applied .

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reduction pipe part, 2 ... Pump discharge pipe, 6 ... Slurry pump, 7 ... Slurry conduit, 10 ... Pressurized air, 20 ... Center line of reduction pipe part, 101 ... Fluidized bed combustion furnace, 103 ... Cyclone, 104 ... Pressure container, 105 ... Air dispersion plate, 106 ...
Pressurized air, 107: combustion air, 109: fluidized bed, 11
0: Slurry spray nozzle, 120: Coal / water slurry,
121: slurry tank, θ ₁ : reduction angle with respect to the center line

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Kodai Nonaka 6-9 Takara-cho, Kure-shi, Hiroshima Babcock Hitachi Ltd. Inside the Kure factory (56) References JP-A-61-223420 (JP, A) JP-A-62-13923 (JP, A) JP-A-57-80115 (JP, A) JP-A-60-38330 (JP, U) JP-A-4-92128 (JP, U) (58) Fields investigated (Int) .Cl. ⁷ , DB name) F23K 3/00 F23C 10/22

Claims (1)

(57) [Claims] 1. A fuel supply system for supplying a coal / water slurry
In a pressurized fluidized bed combustion furnace equipped with tubes, the water in the slurry
20 to 35 wt%, and the viscosity of the slurry is 10 to
Restriction section of coal / water slurry supply pipe of 20 Pa · s
The aperture angle, toward a flow direction of the slurry, coal and Myzus that the reduced small angle of below 5 degrees with respect to the center line of the supply conduit
Pressurized fluidized bed fuel characterized by having a rally supply conduit
Furnace.