JP3690904B2 - How to transport powder - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for transporting granular materials employed in an ash treatment apparatus for a pressurized fluidized bed boiler.
[0002]
[Prior art]
A conventional apparatus will be described with reference to FIGS.
[0003]
In the conventional pressurized fluidized bed boiler ash treatment apparatus shown in FIG. 4, the pressurized fluidized bed boiler 1 pressurizes the interior of the boiler to about 10 atm, coal from the coal transport pipe 2, and air from the air transport pipe 3. To form a fluidized bed A in the boiler and burn coal.
[0004]
Coal combustion ash generated at this time flows into the dust removing device 5a through the exhaust pipe 4 together with the combustion gas, and is separated into combustion ash and combustion gas in the dust removing device 5a. The combustion gas is not shown in the drawing through the exhaust pipe 6. Supplied to the gas turbine.
[0005]
On the other hand, the combustion ash remains in the dust removing device 5a, gradually descends to the lower hopper 5b, and is supplied from the gas supply pipes 18 and 20 arranged in two stages above and below the lower hopper 5b. The fluidized gas is fluidized and the fluidized bed B is formed at this position.
[0006]
The ash in the fluidized bed B is adjusted by the gas supplied from the gas supply pipe 15 so as to have a solid-gas ratio suitable for transportation. Be transported to.
[0007]
A gas flow control valve 19 is provided in the gas supply pipe 20 in the gas supply pipe 15 for performing ash transport through the gas supply pipes 20 and 18 and the suction mouse 7 for forming the fluidized bed B. A gas flow control valve 17 is provided in the gas supply pipe 18, and a gas flow control valve 14 is provided in the gas supply pipe 15, and the gas from the upstream gas supply pipe 13 is divided and the gas supply pipe is provided. A predetermined amount of gas required by each of 20, 18, and 15 can be supplied.
[0008]
The former carrier gas out of the carrier gas and the ash flowing into the ash collecting device 9 through the suction mouse 7 and the ash transport pipe 8 is purified by the filter 10 and the exhaust pipe 12 while the flow rate is adjusted by the valve 11. The latter ash is left in the filter 10 and accumulated in the ash collecting device 9 and discharged from the lower part to the outside.
[0009]
5 shows in detail the relative relationship between the fluidizing gas supply pipe 20 on the upper side of the lower hopper 5b, the fluidizing gas supply pipe 18 on the lower side, the suction mouse 7 and the like in the dust removing device 5a. FIG. 6 shows the arrangement relationship of the fluidizing gas supply pipes 20 and 18 with respect to the dust removing device 5a in detail by taking the VI-VI cross section of FIG.
[0010]
That is, the gas supply pipe 20 for fluidization arranged on the upper side has four gas supply pipes 20a, 20b, 20c, and 20d, and the gas supply pipe 18 for fluidization arranged on the lower side similarly has four. The gas supply pipes 18a, 18b, 18c, and 18d are arranged in two stages so as to open substantially in the tangential direction with respect to the dust removing device 5a.
[0011]
Now, in such an arrangement, in the case of ash having very poor fluidity such as coal combustion ash generated in a pressurized fluidized bed boiler, the upper and lower gas supply pipes 20a to 20d, 18a to If the fluidizing gas is not supplied from 18d, the ash suction state in the lower hopper 5b of the dust removing device 5a shows the aspect shown in FIG.
[0012]
That is, the flow of ash in this case is a flow in which a gas passage called a rat hole C is formed upward from the position of the suction mouse 7, and it becomes impossible to suck and discharge ash particles by the suction mouse 7. .
[0013]
However, even the ash with poor fluidity described above flows at the upper and lower two-stage positions using the four gas supply pipes 20a to 20d and 18a to 18d for fluidization provided in contact with each other. FIG. 8 shows the state of ash suction in the case of conversion.
[0014]
In this case, most of the gas supply pipe 20a to 20d, since 18a~18d is used, a large number of bubbles D ₁ from these things, D _2, · · D _n is generated, ash uniform fluidized bed B, and this fluidized ash _{E 1, E 2, ·· E} n is sucked easily by the suction mouse 7, and transferred to smoothly ash collecting device 9 via the ash transport pipe 8.
[0015]
[Problems to be solved by the invention]
In the above-mentioned conventional ones, it is necessary to use a large amount of pressurized gas to fluidize the granular material having poor fluidity, and thus the transportation efficiency is inevitably lowered. is there.
[0016]
In addition, the combustion fluid ash of a pressurized fluidized bed boiler contains a large amount of unburned carbon, so if low-priced compressed air is used as the fluidizing gas, it will ignite and the ash temperature will rise and agglomerate ( In order to prevent this, it is necessary to use an expensive inert gas such as nitrogen gas. If such a large amount of gas is used, the cost increases and the economic efficiency of the plant decreases. There are problems such as.
[0017]
An object of the present invention is to solve these problems in the prior art and provide a low-cost, reliable and accurate fluidized bed that can transfer combustion ash and the like toward the downstream. To do.
[0018]
[Means for Solving the Problems]
The present invention has been made in order to solve the above-described problems. In the method of transporting a granular material, the fluidized gas is injected into the granular material layer to form a fluidized bed and the granular material is sucked and transported. The shut-off valve provided in the gas inlet pipe is controlled to open and close by a controller, and fluidized gas is introduced until the porosity of the fluidized bed particles reaches the maximum porosity, and then the porosity decreases to a minimum value. The method of transporting the granular material for transporting the granular material is provided by repeatedly charging and stopping the fluidizing gas until the fluidizing gas is stopped and then repeatedly charging and stopping the fluidizing gas. is there.
[0019]
In other words, the controller is operated to select the timing until the porosity of the fluidized bed particles reaches the maximum porosity and until the porosity decreases to near the minimum value , and the shutoff valve is opened and closed to fluidize. By adjusting and controlling the gas injection, the fluidized bed can be reliably maintained while waste of the fluidized gas is eliminated and efficient operation can be performed.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to FIGS.
FIG. 1 shows a schematic configuration of a granular material transport apparatus in a pressurized fluidized bed boiler ash treatment apparatus according to the present embodiment.
[0021]
Since the basic configuration is the same as the conventional one described above, in this embodiment, the same parts as those of the conventional one are denoted by the same reference numerals and shown in the drawings. The explanation to be done was omitted and the explanation was made concisely.
[0022]
That is, in this embodiment, a shutoff valve 30 is provided upstream of the gas supply pipes 18 and 20 for supplying fluidizing gas to the lower hopper 5b portion of the dust removing device 5a, and the shutoff valve 30 is controlled to open and close. A controller 40 is provided so that the fluidized gas can be selected as required and intermittently performed.
[0023]
Usually, there is a relationship as shown in FIG. 2 between the superficial velocity U of the fluidized gas charged into the fluidized bed, the pressure loss ΔP of the fluidized bed gas, and the porosity e of the particles.
[0024]
That is, when the fluidizing gas is introduced into the powder bed and the flow rate is gradually increased and the superficial velocity U is increased, the pressure loss ΔP of the gas increases, and the fluidization starting velocity U _{mf reaches} the maximum. Become.
[0025]
Thereafter, even if the superficial velocity U is further increased, the pressure loss maintains a constant value ΔP _m and a stable fluidized bed is formed. Therefore, the stable superficial velocity U ₀ for forming this stable fluidized bed is: In general, a superficial velocity slightly higher than the fluidization start velocity U _mf is selected, and its value is standardized.
[0026]
On the other hand, for the porosity e of the particles, but continues maintaining a substantially constant value e ₀ does not increase to the vicinity of the fluidization velocity U _mf, become suddenly increased past the fluidization velocity U _mf, the fluidized bed At the stable superficial velocity U ₀ position when is stabilized, the maximum porosity e _max is obtained.
[0027]
Therefore, when fluidizing gas is introduced into the particle layer and fluidized, the particle porosity e is larger than the initial constant value e ₀ , in other words, the particle porosity e is initially constant. When the value is greater than e ₀ , it can be said that the fluidity of the powder is very good.
[0028]
In the present embodiment, the shutoff valve 30 is controlled to open and close by the controller 40, and the fluidized gas in the fluidized bed is intermittently supplied with the input time T _i and the input stop time T ₀ being determined. The change in the porosity e will be described with reference to FIG.
[0029]
During the charging time T _{i when} the superficial velocity is set to the stable superficial velocity U ₀ and the fluidizing gas is introduced, the particle porosity e becomes the maximum porosity e _{max and the} particle layer is a stable fluidized bed. Thus, the suction and transfer of particles through the suction mouse 7 and the ash transport pipe 8 are also stably performed.
[0030]
Next, when the shutoff valve 30 is closed by the controller 40 and the supply of the fluidizing gas is stopped, the particles gradually settle, and the porosity e gradually decreases toward the value of the porosity e ₁ along the solid line a. Become.
[0031]
Therefore, by setting the porosity e ₁ in this case to a value larger than the minimum value e ₀ , the particle layer maintains the formation of the fluidized bed during the charging stop time T ₀ and the particles are sucked and transferred continuously. be able to.
[0032]
When the fluidizing gas charging stop time T ₀ elapses, the controller 40 opens the shutoff valve 30 and charges the fluidizing gas again, so that the porosity e increases and reaches the maximum porosity e _max. Fluidized bed.
[0033]
If the fluidization gas charging stop time T ₀ is too long, the particle porosity e continues to decrease along the phantom line b, and finally reaches the minimum value e ₀ , so the porosity e is a solid line. It is desirable to set the fluidized gas charging stop time T ₀ so as to return and rise along a.
[0034]
As described above, according to the present embodiment, the fluidizing gas charging time T _i and the charging stop time T ₀ are determined, and the shutoff valve 30 is controlled to be opened and closed by the controller 40 to maintain fluidization of the particle layer. Particles are transported continuously and stably, and the amount of fluidized gas used is calculated based on the charging time T _i and the charging stop time T ₀ compared to the case where it is continuously charged. Then, the amount can be reduced by T _i / (T ₀ + T _i ), which greatly contributes to cost reduction.
[0035]
The specific values of the fluidizing gas charging time T _i and the charging stop time T ₀ are determined by the size of the target particles (particle diameter) and physical properties such as the adhesion of the particles. Generally, an appropriate value for the charging time T _i is about 5 to 10 seconds, whereas a charging stop time T ₀ can be 10 to 20 times as long.
[0036]
Although the present invention has been described with reference to the illustrated embodiment, the present invention is not limited to this embodiment, and it goes without saying that various modifications may be made to the specific structure within the scope of the present invention. Absent.
[0037]
【The invention's effect】
As described above, according to the present invention, in the method for transporting a granular material in which a fluidized gas is introduced into the granular material layer to form a fluidized bed and the granular material is sucked and transported, the shutoff valve provided in the fluidized gas input pipe The controller is controlled to open and close the fluidized gas until the porosity of the fluidized bed particles reaches the maximum porosity, and then the fluidized gas is charged until the porosity decreases to a minimum value. Stop and then re-inject the fluidizing gas, and repeat the charging and stopping of the fluidizing gas to transport the granular material, until the porosity reaches the maximum porosity or the porosity is By selecting the timing until it drops to near the minimum value and controlling the opening and closing of the shutoff valve by the controller, adjusting and controlling the flow and stop of fluidization gas, the fluidized bed formation is reliably maintained while flowing Functionally eliminate waste of chemical gas Economic and in which it was possible to implement high-efficiency operation.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory diagram showing a schematic configuration of a granular material transport device according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram showing the relationship between the superficial velocity of a fluidized bed, pressure loss, and particle porosity.
FIG. 3 is an explanatory diagram showing temporal changes in the porosity of particles when fluidizing gas is intermittently introduced in the present embodiment.
FIG. 4 is an explanatory diagram showing the relationship between the superficial velocity of a conventional fluidized bed, pressure loss, and particle porosity.
FIG. 5 is an explanatory diagram showing an enlarged main part of FIG. 4;
6 is an explanatory view showing a cross section taken along line VI-VI in FIG. 5;
7 is an explanatory diagram showing an example of the operation in the portion of FIG.
FIG. 8 is an explanatory view showing another example of the operation in the part of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pressurization fluidized bed boiler 2 Coal conveyance pipe 3 Air conveyance pipe 4 Exhaust pipe 5a Dust removal apparatus 5b Lower hopper 6 Exhaust pipe 7 Suction mouse 8 Ash transport pipe 9 Ash recovery apparatus 10 Filter 11 Valve 12 Exhaust pipe 13 Gas supply pipe 14 , 17, 19 Gas flow control valves 15, 18, 20 Gas supply pipes 18a, 18b, 18c, 18d Gas supply pipes 20a, 20b, 20c, 20d Gas supply pipe 30 Shut-off valve 40 Controller A Fluidized bed B Fluidized bed C Rathole _{D 1, D 2, ·· D} n bubbles _{E 1, E 2, ·· E} n ash

Claims (1)

In a method for transporting powder particles in which a fluidized gas is injected into the particle layer to form a fluidized bed and the particles are sucked and transported, the shut-off valve provided in the fluidized gas input pipe is controlled to open and close by a controller. The fluidizing gas is introduced until the porosity of the fluidized bed particles reaches the maximum porosity, and then the fluidizing gas is stopped until the porosity is reduced to a minimum value. of gas input reintroduction fluidizing gas, by repeating the stop, the method for transporting granular material, characterized by transporting the granules.

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