JPH0522811B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is a method for stably supplying granular materials such as pulverized coal and pulverized coke to combustion devices such as boilers and kilns through an air flow conveying line. This invention relates to a powder and granular material quantitative supply device.

[Conventional technology]

Conventionally, as a device for supplying granular fuel such as pulverized coal from a normal pressure storage bunker or hopper to a pressurized pneumatic conveyance line, as shown in FIG.
Between the storage bunker 1 under atmospheric pressure and the airflow conveyance line 2 under pressure, a plurality of pressure seals (two in FIG.
An upper pressurized tank 5 and a lower pressurized tank 6 are installed in series, and a seal valve, an exhaust valve 7 provided in the pressurized tank, and an upper tank pressure equalization valve 8 are used to input the feed into the pressurized tank. A method (hereinafter referred to as a lock hopper method) is used in which the feed material is stably and continuously supplied to the conveyance line 2 by opening and closing in a predetermined order during discharge. 10 is a pressure equalizing pipe, and 11 is a partition gate.

The operating method of the conventional lock hopper system described above will be explained below. In order to charge the powder and granules to be fed into the upper pressurized tank 5, the upper seal valve 3 and the lower seal valve 4 are used.
is closed, open the exhaust valve 7, and open the upper pressurized tank 5.
After that, the upper seal valve 3 is opened and the feed material is introduced. After a certain amount of injection is completed, the upper part of the Seal valve 3 and exhaust valve 7
is closed. During this time, in the same manner, the feed material received in the upper pressurized tank 5 and already transferred to the lower pressurized tank 6 is being supplied to the conveyance line 2. When it is detected that the lower pressurized tank 6 has been drained completely or the lower limit storage amount has been drained based on the level switch or timer setting, conveyance line pressure, etc., the operation starts draining from the upper pressurized tank 5 to the lower pressurized tank 6. Start. To discharge to the lower pressurized tank 6, open the upper tank pressure equalization valve 8, make the internal pressures of the upper pressurized tank 5 and lower pressurized tank 6 the same pressure, and then open the lower seal valve 4 to discharge the feed material. Discharge. When the level switch installed in the lower pressurized tank 6 completes the acceptance into the lower pressurized tank 6, the upper tank pressure equalization valve 8 and the lower seal valve 4 are opened, and the upper pressurized tank 5 is ready for the next input. Move on to action. By alternately opening and closing each of the seal valves, exhaust valves, and pressure equalization valves in this manner, it becomes possible to supply the material from the storage bunker 1 under atmospheric pressure to the conveyance line 2 under pressure.

[Problem that the invention seeks to solve]

Most of the above-mentioned conventional lock hopper type devices are used for the purpose of transportation, and the quantitative nature and stability of the supply amount are not a concern. However, when such a lock hopper type powder supply device is employed in a combustion device such as a boiler or a kiln, quantitative performance and stability are essential.

FIG. 8 shows the discharge characteristics of the feed material by the above-mentioned lock hopper system. In the figure, sudden changes occur as shown in parts A and B surrounded by a chain line circle, so when used in a combustion device such as a boiler, the amount of solid fuel to be transported is not stable, so combustion instability, and in severe cases it can lead to misfires and cannot be used. This cause is due to fluctuations in the internal pressure of the lower pressurized tank 6, and part A shows the decrease in supply amount due to the drop in the internal pressure of the lower pressurized tank 6 when the upper tank pressure equalizing valve 8 is opened, and the subsequent pressure equalizing pipe. 10 shows the recovery of the supply amount due to the pressure recovery, and part B shows the increase in the supply amount due to the increase in internal pressure due to the injection of feed into the lower pressurized tank 6, and the subsequent recovery of the supply amount due to pressure recovery by the pressure equalization pipe 10. It shows.

The present invention has been made in view of the above points, and aims to provide an apparatus that improves the supply stability of the above-mentioned lock hopper type powder supply apparatus and enables smooth quantitative supply. It is something.

[Means for solving problems]

The first invention will be explained with reference to FIG.
A plurality of pressurized tanks 5 and 6 that are pressure-sealed by seal valves 3 and 4 are provided in series between the storage bunker 1 or hopper under atmospheric pressure and the airflow conveyance line 2 under pressure. By opening and closing the exhaust valve 7 and pressure equalization valve 8 provided in the pressurized tank in accordance with a predetermined order when feeding and discharging the feed into the pressurized tank, the feed is transferred to the conveying line 2. In a powder supply device that stably and continuously supplies powder and granules to
An on-off valve 17 is connected to the pressure relief pipe 13 from the lowermost pressurized tank,
It is characterized in that a pressure detection end 14 is provided in the lowermost pressurized tank, and a pressure regulating valve 16, an on/off valve 17, and the pressure detection end 14 are connected via a regulator 15.

In this case, the internal pressure of the lowermost pressurized tank is set to the detection pressure of the pressure detection end installed downstream of the conveyance line flow rate control valve and upstream of the feed material supply port to the conveyance line. It may be configured to control to a value plus a predetermined value determined as a function of quantity.

In addition, as shown in FIG. 2, the lowermost pressurized tank 6
A quantitative cutting device 18 such as a rotary leaf feeder or screw feeder is installed at the outlet of the
By changing the number of rotations, the supply amount may be adjusted and the range in which fixed quantity supply is possible may be expanded.

The second invention will be described with reference to FIGS. 3 to 5, in which a pressure seal is established between a storage bunker 1 or hopper under atmospheric pressure and an air flow conveying line 2 under pressure by a seal valve. Multiple pressurized tanks are installed in series, and seal valves, exhaust valves, and pressure equalization valves provided on the pressurized tanks are opened and closed in a predetermined order when feeding materials to and from the pressurized tanks. In this way, in a powder supply device that stably and continuously supplies the feed material to the conveyor line, an air supply pipe equipped with a pressure control valve is connected to the lowest pressurized tank, and the air supply pipe from the lowest pressurized tank is An on/off valve is provided in the pressure relief pipe, a pressure detection end is provided in the bottom pressurized tank, the pressure regulating valve, the on/off valve, and the pressure detection end are connected via a controller, and a load cell type is installed in the bottom pressurized tank. A weighing device 21 is provided, and the actual supply amount within a certain period of time is determined from a weighing signal that changes over time as feed material is put in and discharged from the bottom pressurized tank, and this and the amount of feed under the bottom pressurized tank are calculated. Compare the integrated value of the rotation speed signal given to the quantitative cutting device 18 such as a rotary leaf feeder or screw feeder based on a function set from a predetermined relationship between the cutting amount and the rotation speed, and The present invention is characterized in that a control system is provided which corrects the functional relationship between the cutting amount and the number of revolutions in order to reduce this deviation if a deviation larger than the ratio of .

In this case, as shown in FIG.
A, 18b, and 18c may be provided in plural units for one lowermost pressurized tank, so that the supply amount can be adjusted simultaneously and independently to different destinations.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, and shows a lock hopper type powder and granular material quantitative supply device having an internal pressure control mechanism. The device in this example is
In the conventional lock hopper type device shown in FIG. 7, there is an air supply pipe 12 for blowing high-pressure tank internal pressure increasing gas from the transfer line 2, a pressure relief pipe 13, and pressure detection to detect the internal pressure of the lowest pressurizing tank 6. Edge 1
4, controller 15, pressure control valve 16 of air supply pipe 12,
A solenoid valve 17 (on/off valve) is added to the pressure relief pipe 13.

Next, the operation of the apparatus shown in FIG. 1 will be explained.
When the upper tank pressure equalizing valve 8 is opened as shown in section A shown in FIG. An operation signal corresponding to the difference between the set pressure and the rate of change is applied from the controller 15 to the pressure regulating valve 16, and the supply amount of pressurized gas is increased to compensate for the drop in internal pressure. Also, like part B,
When the internal pressure increases due to the introduction of the feed material into the lower pressurized tank 6, the pressure regulating valve 16 is throttled to reduce the amount of pressurized gas supplied to the lower pressurized tank 6. In order to increase the followability of the internal pressure change of the basic internal pressure regulating function by the pressure regulating valve 16, a pressure relief pipe 13 is provided which connects the lower pressurized tank 6 and the conveyance line 2 via a solenoid valve 17. This pressure relief pipe 13 is normally closed, and when the internal pressure of the lower pressurized tank 6 reaches an upper limit value set within a certain range from the set value, the solenoid valve 17 is closed to accelerate the internal pressure drop, and it is normally open. There is a usage in which the solenoid valve 17 is closed when the lower limit value is reached, but this selection is determined by the resistance determined by the structure of the lower pressurized tank 6 and the connection part of the transfer line 2, the structure of the pressure equalization valve 8, the seal valves 3 and 4, This is done based on the pressure fluctuation characteristics of the system determined by the pressurized tank capacity, the number of pressurized tanks arranged in series, etc. If the pressure fluctuation range is relatively small and gentle, it is possible to operate with the pressure relief pipe 13 open at all times, and if it is necessary to further improve controllability, a pressure regulating valve may be provided on the pressure relief pipe side as well. Of course, this improves followability.

When a certain pressure is applied to the lower pressurized tank 6, the powder and granules in the lower pressurized tank 6 are pushed out to the conveyance line 2, but the lowermost pressurized tank (lower pressurized tank)
As shown in FIG. 9, the internal pressure and the supply amount have a certain functional relationship, although they vary depending on the arrangement and pipe diameter of the conveying line 2. In the figure, indicates the difference depending on the properties (particle size, density, etc.) of the conveyed material. Further, FIG. 10 shows the relationship between the pressure difference between the transport line pressure near the connection point between the lower pressurized tank 6 and the transport line 2 and the tank internal pressure, and the supply amount.

According to FIG. 10, since the relationship between the two is almost linear, if this pressure is controlled using the functional relationship of the supply amount and the pressurized tank internal pressure is controlled using the device of the first invention. , it becomes possible to smoothly and quantitatively supply a supply amount at an arbitrary flow rate, which was impossible with the conventional lock hopper type supply machine (Claim 2 of the claim). Note that in FIGS. 9 and 10, solid lines indicate the control range.

However, with the above method, there is a control range (range where stable supply is possible). With this method, when the supply amount is lowered, the influence of disturbances such as natural flow from the lower pressurized tank 6 and fluctuations in the pressure of the conveyance system becomes large, making it difficult to supply a constant amount with constant accuracy. becomes. Therefore, in the range of low supply amount, the control range is exceeded as shown in FIGS. 9 and 10. The invention recited in claim 3 has been made in order to expand the above-mentioned control range. The configuration of the present invention is shown in FIG. A variable quantitative cutting device 18 such as a variable speed rotary feeder or a variable speed screw feeder is installed at the outlet of the lower pressurized tank 6 of the lock hopper type quantitative feeding device having a quantitative feeding function as described in claim 2. According to the present invention, the amount discharged from the lower pressurized tank 6 is regulated by the amount dispensed by the quantitative dispensing device 18, so it is possible to maintain the supply amount at a constant accuracy even in a low flow rate region. It is possible to expand the control range. In this case, the internal pressure of the lower pressurized tank is determined by the method described in claim 2 in order to maintain the differential pressure between the metered amount cutting device 18 and the conveyance line 2 at a constant value so that the differential pressure before and after the quantitative cutting device 18 is constant. controlled. Reference numeral 20 denotes an arithmetic/adjuster that generates a rotational speed signal in response to a cutting request signal.

In the quantitative feeding device according to claim 3 above, the amount of material to be fed to the conveyance line 2 is determined by cutting out the material to the quantitative cutting device 18 in advance through a cutting test simulating actual usage conditions. The relationship between the request signal or the rotational speed of the metered cutting device and the amount to be dispensed is grasped, and the metered supply is performed according to this relationship, but the characteristics of the feed material (density, particle size, etc.)
If this changes, the relationship between the dispensed amount and the rotational speed will be different from the previously set relationship, and an error will occur between the requested cutout amount and the actual supplied amount.

Claim 4 provides the above-mentioned cut-out requirement amount,
This was invented to eliminate the error between the actual supply amount and the amount supplied. That is, as shown in FIG. 3, a load cell type weighing device 21 is provided in the lowermost pressurized tank 6 in which the quantitative feeder described in claim 3 is installed, and a load cell type weighing device 21 is installed to calculate the load cell signal and calculate the above-mentioned request signal. A rotational speed signal corresponding to the rotational speed is given to the quantitative cutting device 18.

As shown in FIG. 4, the weighing signal of the load cell has a sawtooth-like repeating waveform, and therefore the supply amount must be subjected to temporal calculation processing. That is, for a certain period of time (lower seal valve 4
The supply amount per hour is calculated by dividing the increment in the weighed value (load cell measurement signal) (excluding the time when the cell is open) by the section time.When this device is applied to a fuel supply device such as a boiler Since the required supply amount changes from moment to moment depending on the boiler load, differential type calculation processing is not appropriate. Therefore, in the present invention, as shown in FIG. 4, the load cell weighing signal and the rotation signal are integrated within a certain period of time, the two integrated values are compared, and a cutting request is made sequentially so that the deviation is within a specified value. The fixed amount supply is continued with high precision while correcting the functional relationship between the signal and the rotational speed signal.

FIG. 5 shows details of the arithmetic/adjuster 20. In FIG. 5, 22 is a rotation speed setting device, 23
is a controller, 24 is a pretreatment filter, 25, 26
27 is an integrator, 27 is a comparison calculator, and 28 is a function type setter.

Claim 5 is defined as claim 3.
This invention shows how to cope with the case of increasing the capacity or supplying to multiple destinations, and as shown in FIG. It is equipped with quantitative cutting devices 18a, 18b, and 18c that can adjust the amount of discharge.In the case of the present invention, the control pressure in the pressure hopper is determined by the difference between the internal pressure of each conveyance line 2a, 2b, and 2c and the pressure tank. This is done using the average value of the pressures or an arbitrary differential pressure that represents each pressure.

〔Effect of the invention〕

Since the present invention is configured as described above, it is possible to reduce the range of pressure fluctuations in the pressurized tanks caused by the opening and closing of the seal valves associated with the introduction and discharging of feed materials into each pressurized tank. This has the effect of stably and quantitatively supplying the granules to the pneumatic transport line.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of the powder and granular material quantitative supply device of the present invention, Figs. 2 and 3 are explanatory diagrams showing other examples of the device of the present invention, and Fig. 4 is a load cell weighing signal, rotation Graph showing the relationship between signal and time, FIG. 5 is a detailed diagram of the arithmetic/adjuster, FIG. 6 is an explanatory diagram showing still another example of the device of the present invention, and FIG. 7 is an explanatory diagram of the conventional device. , Fig. 8 is a graph showing the discharge characteristics of the feed material in a conventional device, Fig. 9 is a graph showing the relationship between the internal pressure of the lowermost pressurizing tank and the supply amount, and Fig. 10 is a graph showing the conveyance line and the lowermost pressurizing tank. It is a graph showing the relationship between the differential pressure with the tank and the supply amount. 1...Storage bunker, 2, 2a, 2b, 2c...
... Air flow conveyance line, 3 ... Upper seal valve, 4 ...
Lower seal valve, 5... Upper pressurized tank, 6... Lower pressurized tank, 7... Exhaust valve, 8... Upper tank pressure equalization valve, 10... Pressure equalization pipe, 11... Partition gate,
12...Air supply pipe, 13...Pressure relief pipe, 14...
Pressure detection end, 15... Controller, 16... Pressure regulating valve, 17... Solenoid valve, 18, 18a, 18b, 1
8c...Quantitative cutting device, 20...Calculation/adjustment device, 21...Load cell type weighing device, 22...Rotation speed setting device, 23...Controller, 24...Pretreatment filter, 25, 26...Integrator 27...Comparison calculator, 28...Function type setting device.

Claims (1)

[Claims] 1. A plurality of pressurized tanks pressure-sealed by seal valves are provided in series between a storage bunker or hopper under atmospheric pressure and an airflow conveyance line under pressure,
Seal valves and exhaust valves provided on pressurized tanks,
A powder supply device that stably and continuously supplies the feed material to the conveyor line by opening and closing the pressure equalization valve in accordance with a predetermined order when feeding and discharging the feed material into a pressurized tank. , an air supply pipe equipped with a pressure adjustment valve is connected to the lowest pressurized tank, an on/off valve is installed in the pressure relief pipe from the lowest pressurized tank, and a pressure detection end is installed in the lowest pressurized tank to adjust the pressure. A powder or granular material quantitative supply device characterized in that a valve, an on-off valve, and a pressure detection end are connected via a controller. 2 The internal pressure of the lowermost pressurized tank is adjusted to the detection pressure of the pressure detection end installed in the range downstream of the conveyance line flow rate control valve and upstream of the feed material supply port to the conveyance line, and the amount of feed material supplied is 2. The powder and granular material quantitative supply device according to claim 1, wherein the control is performed to a value obtained by adding a predetermined value determined as a function. 3. By installing a quantitative cutting device at the outlet of the bottom pressurized tank and changing its rotation speed,
The apparatus for quantitatively feeding powder or granular material according to claim 1 or 2, wherein the feeding amount is adjusted to widen the range in which quantitative feeding is possible. 4 A plurality of pressurized tanks sealed by seal valves are installed in series between a storage bunker or hopper under atmospheric pressure and an airflow conveyance line under pressure,
Seal valves and exhaust valves provided on pressurized tanks,
A powder supply device that stably and continuously supplies the feed material to the conveyor line by opening and closing the pressure equalization valve in accordance with a predetermined order when feeding and discharging the feed material into a pressurized tank. , an air supply pipe equipped with a pressure adjustment valve is connected to the lowest pressurized tank, an on/off valve is installed in the pressure relief pipe from the lowest pressurized tank, and a pressure detection end is installed in the lowest pressurized tank to adjust the pressure. The valve, on-off valve, and pressure detection end are connected via a controller, and a load cell type weighing device is installed in the lowest pressurized tank, and the feed material is put into and discharged from the lowest pressurized tank to measure the temperature over time. The actual supply amount within a certain period of time is determined from the weighing signal that changes over time, and this is fed to the quantitative cut-out device installed under the bottom pressurized tank according to a function set from the predetermined relationship between the cut-out amount and the rotation speed. If a deviation of a certain ratio or more occurs, the functional relationship between the cutting amount and rotation speed is corrected to reduce this deviation, and subsequent feed rate control is performed. What is claimed is: 1. A powder and granular material quantitative supply device, characterized in that it is equipped with a control system that performs the following. 5. A patent claim in which a plurality of fixed-quantity cutting devices are installed at the outlet of the lowest pressurized tank for one lowest pressurized tank, and the supply amount can be adjusted simultaneously and independently to different destinations. Range 3rd
Powder and granular material quantitative supply device described in Section 1.