JPH0522123B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is a method for detecting blockages in fuel conveying pipes that convey powder particles such as pulverized coal and coke in an air stream and supplying them to combustion devices such as boilers and kilns. This relates to recovery methods.

[Conventional technology]

Conventionally, granular fuel such as pulverized coal is supplied from a storage bunker or hopper under normal pressure to a pressurized airflow transport main pipe, and distributed to multiple transport pipes by a distributor for combustion in boilers, kilns, etc. The method of supplying the device is well known. In this conventional method,
I'm relying on visual inspection. Further, the detected value of the pressure inside the conveying pipe may not be able to be detected depending on the position of the blockage.

Furthermore, Japanese Patent Application Laid-Open No. 59-225218 discloses that between the powder or granule material spout and the branch part of the powder or granule material (fuel) supply pipe,
A temperature sensor is installed to continuously detect temperature changes in the pipe, and if the pipe becomes blocked, the fuel flow will stop.
A configuration is described in which the fuel supply pipe is gradually heated by the heat of the combustion chamber, and its temperature becomes higher than that of other fuel supply pipes, and this temperature is detected by a temperature sensor to detect clogging.

Japanese Unexamined Patent Publication No. 59-145416 describes a configuration in which a pressurized gas supply line is connected to a transfer pipe for incinerated material (sludge) to purge the inside of the transfer pipe.

[Problem to be solved by the invention]

When supplying solid fuel by air flow conveyance, increasing the solid-air ratio of the conveyance and reducing the diameter of the conveyance line in order to increase the conveyance efficiency may increase the possibility of clogging of the conveyance pipe during conveyance. Blockage is important from the viewpoint of combustion control. However, as equipment becomes larger and the number of conveyor pipes increases, it becomes difficult to check for blockages. Particularly in the case of a fluidized bed combustion boiler, even if a distributor with a high distribution ratio is used, there are many conveyor pipes in the vicinity of the boiler.

In order to detect a blockage, the difference between the temperature of the main pipe and the branch pipe must be detected to detect the blockage under all conditions. For example, when the pipe is cold, such as during startup, it takes time to rise to the set temperature (assuming 50°C), resulting in a false detection as a blockage; conversely, when the pipe is hot, the set temperature (50°C)
It takes a long time for the voltage to drop to (in the case of Therefore,
When measuring the temperature of each branch pipe as in Japanese Patent No. 59-225218, the temperature difference is not detected, so clogging cannot be detected in all operating conditions.

When a pipe becomes clogged, gas flows through the main pipe, but not through the clogged pipe, resulting in a drop in temperature, which causes a deviation and is detected. If the pipe is located in a place where the temperature does not drop when it is closed, no temperature deviation will occur, so the transport pipe must be designed to be unaffected by the ambient temperature.

In addition, the invention described in JP-A-59-145416 is
This is a device that sends sludge in the pipes back to the hopper when the equipment is stopped, and is not a device that purges the blocked pipes and sends the blockages into the furnace while the boiler continues to operate.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for early detection and recovery of conveyance tube blockage.

[Means and actions for solving the problem]

In order to achieve the above object, the fuel transfer pipe blockage detection and recovery method of the present invention is as shown in FIGS.
To explain with reference to the figure, in a method of supplying granular fuel to a combustion device by air conveyance via a conveyor main tube 1, a distributor 2, and a plurality of conveyor tubes 3, the conveyor gas is lowered from the ambient temperature of the conveyor tubes 3. The temperature is heated to a temperature of 10 to 100°C, and a thermometer 14 is installed on the surface of each conveyor tube. Deviation between the measured value of the thermometer installed in the pipe and the average value; Difference, () The difference between the measured values, the measured value of the thermometer 14 provided in each conveying pipe 3 connected to the same distributor 2, and the measured value of the thermometer 8 provided in the conveying main pipe 1. When at least one of the above () to () is detected, and the value is out of a preset range, it is assumed that the conveying pipe 3 is blocked, and a blockage signal is issued. The conveyance pipe stop valve 15 provided in each conveyance pipe 3 is closed by the signal, and the conveyance pipe stop valve 15 is closed.
It is characterized by opening the on-off valves 17 provided upstream and downstream of the purge gas and blowing in high pressure gas for purging.

Maintaining the carrier gas 10-100°C above ambient temperature is important for clogging detection.
This is an important condition in the design of conveyor pipes.

Note that there is variation in the temperature of each conveying pipe, and if the difference between the conveying gas and the ambient temperature of the conveying pipe is less than 10℃,
It sends out false signals and is undesirable.

Also, the difference between the carrier gas and the ambient temperature of the carrier pipe is 100℃.
If the temperature exceeds 1, the properties of the conveyed object may change, and since the temperature is high, there will be a delay until the temperature can be detected, resulting in a longer detection time.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2. Reference numeral 1 denotes a transport main pipe for airflow transporting powder and granular material, and a plurality of transport pipes 3 are branched from this transport main pipe 1 via a distributor 2. 4 is the transport main pipe 1
5 is a heater using steam or the like as a heating source; 6 is a bleed chamber; the upper part of the bleed chamber 6 is connected to a powder storage bunker. 7 is a damper, 8 and 10 are thermometers, 11 is a flow control valve, 12 is a temperature control device, and 13 is a fluidized bed boiler.

In the apparatus configured as described above, the carrier gas is kept 10 to 100° C. higher than the ambient temperature (outside air temperature) of the carrier pipe 3 by the heater 5 and the temperature controller 12. This temperature adjustment is performed by a thermometer 8 or 10 provided on the transfer main pipe 1. However, since there is a slight temperature drop between the transport main pipe 1 and the transport pipe 3, this must be taken into consideration.

A thermometer 14 is provided on the surface of each transfer pipe 3 as shown in FIG. Deviation between the measured value of the thermometer on the surface of the connected conveying pipe and the average value, () The measured value of the thermometer 14 provided on the conveying pipe 3 and the measured value of the thermometer 8 provided on the surface of the conveying main pipe 1 () The difference between the measured values, the measured value of the thermometer 14 provided in the conveying pipe 3 connected to the same distributor 2, and the measured value of the thermometer 8 provided in the conveying main pipe 1 When at least one of the above () to () is detected, and the value is out of a preset range, it is assumed that the transport pipe 3 is blocked and a blockage signal is issued A conveyance pipe stop valve 15 that opens and closes in response to this closure signal is provided in each conveyance pipe 3, and on-off valves 17 that operate according to a sequence determined by the closure signal are provided upstream and downstream of this stop valve 15. A high-pressure gas blowing pipe 16 is provided for blowing in high-pressure air for purging. Of course, this recovery operation may be performed manually by obtaining a blockage detection signal.

Since the conveying gas no longer flows through the clogged conveying pipe 3, the surface temperature decreases due to heat radiation to the surroundings. Therefore, blockage can be detected by monitoring the surface temperature of the transport pipe. As a method of monitoring, if the surface temperature is easily affected by the ambient temperature, etc., it is appropriate to calculate the average value of the surface temperature of a specific group in the vicinity and calculate the deviation from it. is large (specific transport pipe installation location,
(depending on the arrangement, transport pipe operation (ON-OFF) mode, etc.), monitor the measured value of each transport pipe thermometer. It is also an effective method to use the temperature difference between the transport main pipe 1 and the transport pipe 3 (branch pipe).

If the detected value is outside the preset allowable deviation range, it is assumed that the conveying pipe is blocked, but if blockage is detected, the stop valve 15 is closed by the detection signal, and the on-off valve 17 is opened to supply high-pressure gas for purging. The upstream and downstream sides of the stop valve 15 are flown simultaneously or separately to push out the blocked powder and granules and restore the flow. It is effective to repeatedly and intermittently blow this high-pressure gas for purging. After performing a predetermined blockage release operation determined by a sequencer 20 built in the control device 18, etc., the blowing of the high pressure purge gas is stopped and the stop valve 15 is opened. 21 is a computing unit;
22 is an alarm device.

In order to improve the detection accuracy of the above blockage detection system, the temperature of the carrier gas is controlled, and the detection end used for temperature control is installed as close as possible to the carrier pipe where blockage is to be detected. However, as seen in the example of the use of a fluidized bed boiler, when there are multiple conveyance lines and operation/stop is performed for each conveyance line, the temperature detection end is connected to the heater 5.
The difference between the surface temperature at the distributor inlet of each conveyance line and the conveyance tube surface temperature is used as the conveyance tube surface temperature in the blockage detection/judgment logic of each conveyance tube.

〔Effect of the invention〕

Since the present invention is configured as described above, it is possible to reliably detect blockage of the fuel transfer pipe in any operating state, and to effectively purge the blocked portion of the fuel transfer pipe to quickly recover the fuel transfer pipe. It has the effect of being able to

[Brief explanation of the drawing]

FIG. 1 is an overall explanatory diagram showing an example of an apparatus for carrying out the method of the present invention, and FIG. 2 is a detailed explanatory diagram of the area around the distributor in FIG. 1. 1... Transfer main pipe, 2... Distributor, 3... Transfer pipe, 4... Blower, 5... Heater, 6... Bleeding chamber, 7... Damper, 8, 10... Thermometer, 11
...Flow control valve, 12...Temperature control device, 13...
... Fluidized bed boiler, 14 ... Thermometer, 15 ... Conveying pipe stop valve, 16 ... High pressure gas blowing pipe, 17 ... Opening/closing valve, 18 ... Control device, 20 ... Sequencer,
21...Arithmetic unit, 22...Alarm device.

Claims (1)

[Scope of Claims] 1. A method for supplying granular fuel to a combustion device via a transport main pipe 1, a distributor 2, and a plurality of transport pipes 3 by pneumatic transport, in which the transport gas is heated to a temperature of 10 to 10°C below the ambient temperature of the transport pipes 3. The temperature is heated to 100°C, and a thermometer 14 is installed on the surface of each conveyor tube. Deviation between the measured value of the provided thermometer and the average value; () Difference between the measured value of the thermometer 14 provided in the transfer pipe 3 and the measured value of the thermometer 8 provided in the transfer main pipe 1; () The difference between the measured values, the measured value of the thermometer 14 provided in each conveying pipe 3 connected to the same distributor 2, and the measured value of the thermometer 8 provided in the conveying main pipe 1 The deviation from the average value of at least one of the above () to () is detected, and when the value is out of a preset range, it is assumed that the conveying pipe 3 is blocked, and a blockage signal is issued. The conveyance pipe stop valve 15 provided in each conveyance pipe 3 is closed, and the conveyance pipe stop valve 15
A method for detecting and restoring blockage in a fuel transfer pipe, which comprises opening on-off valves 17 provided upstream and downstream of the fuel transfer pipe and blowing in high-pressure purge gas.