JPH0154246B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for adjusting the amount of granular material cut out from a pressure-feeding container, and particularly relates to a method for adjusting the amount of pulverized coal cut out from a pressure-feeding container. This provides a method for adjusting the amount of pulverized coal injected into a transport pipe.

In order to supply pulverized coal to each tuyere of a blast furnace, uniform distribution to each tuyere and quantitative ability to inject the amount are required.

Various studies have been conducted regarding quantitative cutting from a pressure-feeding container, and these include (1) a method of forcibly controlling the cutting amount by mechanical means such as a rotary valve, and (2) a method based on the application of fluid mechanics. It is roughly divided into two categories, such as a method of controlling the cutting amount by making full use of a control circuit.

Both of them have been quite effective, and it is hard to argue with the other party, but conventional mechanical means have the drawbacks of changes in the amount of powder cut out over time due to machine wear and increased maintenance costs, and the latter's fluid In the case of a method applying mechanics, the prior art provides a method of controlling the amount of cutout by controlling the pressure of the pressure-feeding container; The pressure in the container is raised and lowered in the same way to adjust the cutting amount to a fixed amount, but the disadvantage is that the responsiveness of the pressure control system of the pressure-feeding container worsens as the capacity of the pressure-feeding container increases. Currently, there is little control over the situation.

Furthermore, when trying to apply the conventional technology to uniformly distributed transport, mechanical means are unsuitable due to structural constraints, and in the case of pressure control in a pressure-feeding container, which is an application of fluid dynamics, it is difficult to apply it to a blast furnace. For coal that has different transport distances to each tuyere, the only control point is the pressure in the pressure vessel, so the amount of pulverized coal cut into each transport pipe is controlled by the distance of each transport pipe, that is, the resistance. Therefore, the amount of pulverized coal injected into the tuyere with a long distance is smaller than that with the tuyere with a short distance, making it impossible to distribute it evenly. In order to avoid this problem, conventional technology adopts a method in which the length of the other transport pipes is made to match the length of the transport pipe to the farthest tuyere so that the transport distance to each tuyere is equal. The disadvantage is that the layout prioritizes piping, making it impossible to freely choose the piping route.

The present invention overcomes the shortcomings of the prior art and enables multi-distributed quantitative transport which could not be achieved with the conventional method, and will be specifically explained below.

First, the apparatus applied to the present invention is as shown in FIG. 1, in which a pressure vessel 10 is equipped with an air filter 16 at the bottom.
It is equipped with a large number of discharge nozzles 1'...5'.

1...5 are parallel transport pipes that open to each blast furnace tuyere (not shown) and are connected to booster pipes 11... and 15.
It is connected with.

6 is a discharge valve, 7 is a flexible hose for gravitationally insulating the pressure vessel, and 8 is a booster check valve.

9 is a booster flow rate controller, 17 is a pressurized gas pressure controller, and 18 is a powder discharge weight dw/ from the pressure vessel.
This is a measuring device for measuring dt.

In the present invention, when distributing and transporting powder particles from such an apparatus, the pressure pipe 19 is connected inside the pressure vessel 10.
The basic condition is that the pressure is maintained at a constant pressure by pressurized gas flowing from the pressurized gas source 20 through.

In other words, in this state, the pressure required for transportation P _T
is the pressure loss of compressed gas lost in the transport pipe △
If Pa is the pressure loss due to pipe friction of the powder and granules lost in the transport pipe, ΔPs, and the pressure at the end of the transport pipe is Pb, the relationship is expressed by the following equation.

P _T = △Pa + △Ps + Pb …(1) In the above equation, if Pb is at atmospheric pressure, it is considered to be approximately constant, so under the condition that P _T = constant, △Pa + △Ps = P _T −Pb = constant …( It can be seen that the relationship 2) is established.

The present invention is based on the relationship of equation (2), and △Pa
This takes advantage of the fact that there is a relative relationship between and △Ps.

That is, if a larger amount of pressurized gas is flowed into the transport pipe while the pressure P _T in the pressure-feeding container 10 is held constant by the pressurized gas pressure regulator 17, △Pa increases,
The pressure loss ΔPs of the granular material decreases, and the flow of the granular material is restricted.

Note that the above assumes that Pb is at constant atmospheric pressure (1)
In the formula, (△Pa + Pb) + △Ps = constant, so even when there is pressure fluctuation, (△
By setting Pa+Pb) as the manipulated variable, ΔPs can be changed freely.

In other words, by changing the gas flow rate of each booster pipe individually, it is not only possible to distribute the gas equally to each transport pipe, but also easily increase the transport volume of one or more specific transport pipes among multiple transport pipes. .

Therefore, according to the present invention, there is no need to select a piping route, and a free and economical design is possible.In addition, even if the terminal conditions of the transport pipe change or the transport pipe pressure changes, the powder particles will not change. The amount of body transport can be adjusted, and since the method uses flow rate control instead of pressure control, which has poor responsiveness as in the conventional method, the responsiveness is good, and the cutting amount can be adjusted accurately, smoothly, and quickly.

The effectiveness and effects of the present invention will become clear from the following measurement results. First, Fig. 2 shows the pressure of the pressure vessel 10 at 4 kg/cm ² G (constant) in the apparatus shown in Fig. 1.
This shows the change in the amount of cutout with respect to the booster flow rate when transported only to one transport pipe 2, and shows that the amount of cutout can be adjusted in a wide range from 100Kg/hr to 850Kg/hr.

In this case, we measured the rate of change in the cutout amount during transportation, that is, the quantitative property (dw/
The rate of change (assuming dt=357391426Kg/hr as 0) was within the range of ±2%, and the quantitative nature was excellent.

Further, FIG. 3 shows the amount of cutout when the material is transported simultaneously through three transport pipes 1, 4, and 5 under predetermined conditions. From this figure, the transport volume of each transport pipe can be calculated, for example.
If you want to make it 800Kg/hr, the booster flow rate of transport pipe 5 is 35Nm ³ /hr, that of transport pipe 1 is 40Nm ³ /hr,
It can be seen that the value of the transport pipe 4 should be adjusted to 45Nm ³ /hr.

Incidentally, when the average value of the cut amount of each pipe is set to 0 when a fixed amount is cut out and transported to transport pipes 1...5 at the same time, the deviation % of each pipe, that is, the uniform distribution accuracy is ±3
It was %.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the device applied to the present invention, Figure 2 is a schematic diagram of the device applied to the present invention;
The figure and FIG. 3 are graphs showing changes in the cutting amount with respect to the booster flow rate. 1-5...transport pipe, 11-15...booster pipe, 19...pressurized gas pipe.

Claims (1)

[Claims] 1. A method for distributing and transporting powder and granular material, which includes an aerator at the bottom of a pressure vessel and feeds the powder and granular material floated by pressurized gas through a plurality of discharge nozzles into a plurality of transport pipes in which the pressure at the receiving end is approximately constant. In this step, by individually changing the booster flow rate flowing into the booster pipes connected to each transport pipe while keeping the pressure in the aerator constant, the amount of powder per unit time cut from the container into each transport pipe is determined. A method for adjusting the amount of powder or granular material cut out, characterized by adjusting the amount of cut out.