JPH06335628A - Powder feeder - Google Patents

Abstract

PURPOSE:To prevent the damage due to the backflow of high pressure gas in a centrifugal powder feeder for feeding powder into a place under high pressure. CONSTITUTION:To predict the generation of backflow of high pressure gas in its early stage to the utmost, a pressure detector 14 is installed in the central part of a rotor 3. When the detected pressure exceeds the 1st restricted value, the revolution of the rotor 3 is increased to prevent the backflow. And when, what is worse, the pressure in the rotor does not stop rising and exceeds the 2nd restricted value, cutoff valves 2, 10, 13 installed in a particle feeding pipe 1, a particle discharge pipe 9 and a particle return pipe 12 are all closed respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coal gasification combined cycle power plant, a pressurized fluidized bed boiler, a blast furnace in a steel mill, and the like, and a powder supply device for supplying powder under high pressure.

[0002]

2. Description of the Related Art FIG. 4 is a system diagram showing an example of a conventional centrifugal powder feeder for feeding powder under high pressure. The powder is conveyed by air flow to the center of the rotor (3) by the particle supply pipe (1), is compacted by the centrifugal force accompanying the rotation of the rotor into the passage (6) radially extending from the center of the rotor, and is discharged from the nozzle (7). It is discharged into the high-pressure casing (5). Then, it is supplied to the boiler (11) and the like via the discharge pipe (9). Further, some of the particles supplied into the rotor are returned as excess particles to the upstream side of the particle supply pipe (1) via the particle return pipe (12). In addition, (4), (1
5) is a bearing, (8) is a motor, and (16) is a rotor speed detector.

[0003]

In the centrifugal powder feeder as described above, by rotating the rotor at an appropriate rotational speed, the powder is discharged under high pressure and the pressure is sealed by the powder layer. It becomes possible and can drive safely. However, when the rotor speed falls below an appropriate range with respect to the pressure of the casing (5) due to improper driving operation, abnormality of the control device, hardware failure, or the like, the high-pressure gas passes through the rotor internal passage ( Since the particles filled in 6) are pushed back toward the rotor center side, the seal due to the powder layer is broken, and so-called backflow of gas from high pressure to normal pressure occurs. When gas flows backward, particle supply pipe (1), particle return pipe (1)
Since the equipment of the normal pressure system such as 2) is exposed to the pressurized state,
It may cause equipment failure. Furthermore, the particle discharge pipe (9)
Is connected to a gasification furnace, a pressurized fluidized bed boiler, etc., there is a possibility that a high temperature combustion gas will flow back, which will be a serious safety problem.

[0004]

In order to solve the above-mentioned conventional problems, the present invention provides a powder supplied through a particle supply pipe to a central portion of a rotor having a plurality of passages radially provided therein. In the powder supply device configured to discharge under high pressure by the centrifugal force of the rotor and take out through the particle discharge pipe, and to return surplus particles to the upstream of the particle supply pipe through the particle return pipe, in the center of the rotor. A pressure detector is provided in each of the particle supply pipe, the particle discharge pipe, and the particle return pipe, and an automatic shutoff valve is provided, and means for controlling the rotation speed of the rotor based on the pressure detected by the pressure detector and the detection. The present invention proposes a powder supply device characterized in that means for closing all of the above-mentioned automatic shutoff valves based on pressure is provided.

[0005]

The pressure at the center of the rotor is maintained at almost normal pressure while the centrifugal force is working properly, but immediately before the occurrence of the backflow phenomenon, high pressure leak air (or The other pressurized medium) and the flow velocity of the air passing through the particle return pipe increases, so that the pressure at the center of the rotor rises. Therefore, if the pressure is monitored, the occurrence of backflow can be predicted.

Therefore, in the present invention, the increase in the pressure is detected to increase the rotational speed of the rotor to prevent the backflow. If the pressure at the center of the rotor does not drop even if the number of rotations is increased, that is, if backflow cannot be prevented, the automatic shutoff valves provided in the particle supply pipe, the particle discharge pipe, and the particle return pipe should be used. By closing all of them, the influence of backflow is minimized and the safety of the entire device is ensured.

[0007]

FIG. 1 is a system diagram showing an embodiment of the present invention. A pressure detector (1 provided at the center of the rotor (3)
The output signal P of 4) and the output signal N ₀ of the rotor speed detector (16) are input to the calculator (17). Arithmetic unit (1
In 7), a function as illustrated in FIG. 2 is registered in advance, and the following operation is performed on the input signal.

When the pressure signal P is equal to or lower than the set pressure P _{1 at the} alarm point 1 with respect to the rotor speed N ₀ , that is, P ≦ P
_In case of ₁ , the current status is maintained.

When the pressure signal P is larger than the set pressure P _{1 at the} alarm point 1 and equal to or less than the set pressure P _{2 at the} alarm point 2, the pressure P
The rotor rotation speed control signal A is output so as to increase the rotor rotation speed until is less than P _1, and is input to the rotor rotation speed control device (18).

When the pressure signal P becomes larger than the set pressure P _{2 at the} alarm point 2, the shutoff valve signal B is output and sent to the shutoff valve opening / closing device (19), and the particle discharge pipe, the particle supply pipe,
Automatic shutoff valves (2), (10), (13) for the particle return pipe
Close.

FIG. 5 shows the conventional powder feeding apparatus described with reference to FIG. 4, in which the pressure P at the center of the rotor, the rotor speed N, the open / close state of each shutoff valve (manual), and the particle feeding when a backflow occurs. The change in pressure P _a on the upstream side of the system is shown in FIG.
Shows a similar change in this embodiment. FIG. 3A shows the case where the backflow can be prevented by increasing the rotor rotation speed.
(B) is the case where the rotor is mechanically or electrically stopped. In any case, in this embodiment, the pressure increase of the particle supply system is suppressed to be low as compared with the conventional system,
You can drive or stop safely.

[0012]

According to the present invention, the internal pressure of the rotor of the centrifugal powder feeder is monitored, and it is detected at an early stage that a high-pressure gas backflow occurs. By closing the automatic shut-off valves provided in the particle discharge pipe and the particle return pipe, the damage due to the reverse flow of high-pressure gas can be minimized.

[Brief description of drawings]

FIG. 1 is a system diagram showing a powder supply device according to an embodiment of the present invention,

FIG. 2 is a diagram showing an example of a powder pressure alarm setting in the above embodiment.

FIG. 3 is a diagram showing a behavior at the time of preventing backflow in the above embodiment.

FIG. 4 is a system diagram showing an example of a conventional powder supply device.

FIG. 5 is a diagram showing a behavior when a backflow occurs in the above-mentioned conventional powder supply device.

[Explanation of symbols]

 (1) Particle supply pipe (2) Automatic shutoff valve (3) Rotor (4) Bearing (5) Casing (6) Particle passage (7) Nozzle (8) Motor (9) Particle discharge pipe (10) Automatic shutoff valve ( 11) Boiler (12) Particle return pipe (13) Automatic shutoff valve (14) Rotor pressure detector (15) Bearing (16) Rotor speed detector (17) Computer (18) Rotor speed controller (19) ) Shut-off valve opening / closing device

Claims (1)

[Claims] 1. A powder which is supplied through a particle supply pipe to a central portion of a rotor having a plurality of radial passages inside is discharged under high pressure by centrifugal force of the rotor and is taken out through the particle discharge pipe. In the powder supply device configured to return excess particles to the upstream of the particle supply pipe through the particle return pipe, a pressure detector is provided at the center of the rotor, the particle supply pipe, the particle discharge pipe, and the particle return pipe. Each of the pipes is provided with an automatic shutoff valve, and means for controlling the rotational speed of the rotor based on the pressure detected by the pressure detector and means for closing all the automatic shutoff valves based on the detected pressure are provided. Powder supply device.