JPH0659936B2 - Fine powder distribution control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a device for distributing pneumatic pulverized coal to the blast tuyere of, for example, a blast furnace in the steel industry.

[Conventional technology]

An example of a conventional method of a pulverized coal pneumatic feeder is shown in FIG. 3, and its contents will be briefly described. That is, a predetermined amount of pulverized coal is stored in the pulverized coal supply tank 1, the tank 1 is pressurized to a prescribed pressure, and the pulverized coal is fluidized to be cut out in a dense phase state by a pressurizing force and guided to a disperser 2. The carrier gas is made to communicate with the disperser 2 through the pipe 3, where the pulverized coal and the carrier gas are diluted and mixed, and a single distributor up to the distributor 6 installed near the blast furnace 5 in a solid-gas two-phase flow state. The carrier pipe 4 is carried. A mixed flow of pulverized coal and gas enters the distributor 6 having a cylindrical shape from the center of the lower part thereof, diffuses in the distributor 6, and is provided at predetermined intervals along the inner peripheral surface of the peripheral wall of the cylindrical main body of the distributor. Distributing and flowing out to the distribution branch pipes 7a, 7b, ... The mixed flow of pulverized coal and gas is branched branch pipes 7a, 7b, ...
Through the burner 9a attached to the blast furnace tuyere 8a. The pulverized coal air feeding device according to this method can feed equal amount of pulverized coal to a plurality of blowing tuyere and does not use a mechanical distribution device with rotation etc., so it is highly reliable and rational. That's the method.

However, in order to feed an equal amount of pulverized coal to a plurality of blast tuyeres, each distribution branch pipe 7a, 7b after the distributor 6
The precondition is that the pressure drop of the solid-gas two-phase flow in the inside is almost the same. However, in general, various empirical formulas for determining the pressure drop in a solid-gas two-phase flow pipe have been reported, but all of them are based on the experimental results and do not necessarily match the actual values. For this reason, the most effective and efficient way to design each distribution branch in an actual blast furnace is to make all distribution branches the same diameter, length and geometry.

[Problems to be solved by the invention]

The conventional method is a highly reliable and rational method capable of feeding and sucking an equal amount of pulverized coal to a plurality of blowing tuyere as described above.

However, due to recent advances in blast furnace operation technology, it is necessary to control the amount of heat at the tuyere in the blast furnace in operation, and for this reason, a device that can freely change the amount of pulverized coal injected into a specific blast tuyer is required. ing. However, the conventional method has a problem in that the amount of pulverized coal injected into a specific blast tuyere cannot be freely changed, and the present invention is intended to solve this problem.

[Means for solving problems]

It is known that an additional gas is introduced into the specific branch branch pipe after the distributor from the outside of the system to increase the pressure loss in the branch branch pipe, thereby decreasing the flow rate of the pulverized coal in the branch branch pipe. I know it at 57-112231 etc.

A method in which pneumatic pulverized coal is made to flow in from the center of the lower part of the distributor, and is made to flow out to a branch branch pipe whose inlet end is connected to openings provided at predetermined intervals along the inner peripheral surface of the peripheral wall of the cylindrical main body of the distributor. If an additional gas is introduced into the specific branch branch pipe from outside the system, the flow rate of pulverized coal in the distribution branch pipe can be reduced, but if the total amount of pulverized coal introduced into the distributor is constant, the additional gas is introduced. It is easy to understand that the flow rate of pulverized coal in the branch branch pipe increases.

As a result of various experiments conducted by the present inventors, It was found that there is a certain linear correlation between the distribution ratio and the distribution ratio ([target pulverized coal distribution ratio] / [fine coal distribution before control]). Converting the pulverized coal injection amount for each blast tuyere, which is the operation target, in advance to the target pulverized coal distribution ratio,
The amount of additional gas corresponding to the above correlation equation is calculated for each branch branch pipe, and this amount of additional gas is introduced into a predetermined branch branch pipe to easily control the amount of pulverized coal blown into the blast tuyere. It becomes possible.

〔Example〕

An embodiment of the present invention will be described below in detail with reference to FIGS. 1 and 2. FIG. 1 shows an embodiment of a control device according to the present invention.

A predetermined amount of pulverized coal is stored in the pulverized coal supply tank 1, the tank 1 is pressurized to a prescribed pressure, and the pulverized coal is fluidized to be cut out in a dense phase state by a pressing force and guided to a disperser 2, while being conveyed at high pressure. The working gas is communicated through the pipe 3 to the disperser 2, where the pulverized coal and the carrier gas are diluted and mixed, and a single carrier pipe is connected to the distributor 6 installed near the blast furnace 5 in the state of solid-gas two-phase flow. Four
Transporting inside is the same as the conventional method. A mixed flow of pulverized coal and gas enters the distributor 6 having a cylindrical shape from the center of the lower part thereof, diffuses in the distributor 6, and is provided at predetermined intervals along the inner peripheral surface of the peripheral wall of the cylindrical main body of the distributor. A branch pipe with an inlet end connected to a number of openings corresponding to the blast tuyere of the blast furnace (the number of blast tuyere varies depending on the scale of the blast furnace, but generally 20-
Since there are 40 branch pipes, 20 to 40 branch pipes are provided.
In the illustration, two of them are shown as 7a and 7b). Additional gas introduction pipes 10a and 10b and pulverized coal flowmeters 13a and 13b are provided alongside each branch pipe. The mixed flow of pulverized coal and gas is divided into branch branch pipes 7a and 7b and pulverized coal flow meter 13
It is blown into the blast furnace through a burner 9a attached to the blast furnace tuyere 8a through a and 13b.

Next, a method for controlling the amount of pulverized coal blown into a predetermined blast tuyere by the device according to the present invention will be described.

First, the pulverized coal flow rate meter 13a, 13b attached to each branch tributary pipe detects the flow rate of the pulverized coal flowing in each branch tributary pipe without introducing the additional gas.
A signal is sent from b to the arithmetic unit 17. If the number of branch branch pipes is n and the flow rate of pulverized coal detected for each branch branch pipe is w ₁ , w ₂
…… W _n . The computing unit 17 first calculates the distribution rate (k ₁ , k ₂ , ... K _n ) for each branch branch pipe. Here, the distribution rate defines the ratio of the actual pulverized coal flow rate of each branch branch pipe to the flow rate assuming that the pulverized coal is evenly distributed to all branch branch pipes. I.e. Next, a target pulverized coal flow rate (w ₁ ′, w ₂ ′, ... W _n ′) for each branch branch pipe, which is a target for blast furnace operation, is sent to the arithmetic unit 17 via the instruction setting unit 18. The target distribution rate (k ₁ ′, k ₂ ′, ... K _n ′) for each branch branch pipe is calculated based on the target pulverized coal flow rate instructed by the arithmetic unit 17.

Based on the above calculation results, the distribution ratio (K ₁ , K
_2. Calculate K _n ). Here, the distribution ratio (target distribution ratio) / [before additional gas introduction = distribution before control] is defined, that is, K ₁ = k ₁ ′ / k ₁ , K ₂ = k ₂ ′ / k ₂ ……, K _n = k _n ′ /
k _n .

It is an index that takes into consideration the mutual interference of the control effect by the additional gas for each branch branch pipe and the distribution ratio ratio ([target distribution ratio] / [before additional gas introduction = distribution ratio before control]) defined above based on past results. It has been found by the inventors that there is a linear correlation as shown by 19 in FIG. 2 between certain relative amounts of additional gas. This linear correlation has different characteristics (gradient) depending on the pipe length of the branch branch pipe.
The linear correlation of 9 is quantitatively obtained in advance, and the arithmetic unit 17 calculates the relative amount of additional gas corresponding to the distribution ratio obtained above for each branch branch. Here, the relative amount of additional gas is qi, which is the amount of additional gas introduced into the i-th branch branch pipe.
A value obtained by dividing the total amount of additional gas introduced into all branch branch pipes by the number n of all branch branch pipes (that is, Then, it can be defined as [qi-], and the arithmetic unit 17 uses this arithmetic expression to calculate the additional gas amount qi for each branch branch pipe which is as small as possible.

The arithmetic unit 17 sends a signal to the additional gas amount control device 15a of the additional gas amount to be introduced for each branch branch pipe calculated above, and the flow rate control valves 11a and 11b provided in the additional gas introduction pipes 10a and 10b are added to the additional gas. It controls based on the measured value by the flowmeters 12a and 12b.

With the operations described above, it is possible to easily achieve the target pulverized coal flow rate for each branch branch pipe, which is a target for blast furnace operation.

〔The invention's effect〕

As is clear from the above description, in the present invention, when pulverized coal is fed to the blast tuyere of the blast furnace, the pulverized coal flow from a single pulverized coal carrier pipe is distributed and fed to the branch branch pipes to each blast tuyere. In the distribution device, this control is performed even if the pulverized coal distribution or pulverized coal flow rate to the branch branch pipe fluctuates from the target value due to fluctuations in the pressure loss balance between the branch branch pipes and the pressure balance between the tuyeres in the blast furnace, etc. By introducing the amount of additional gas calculated by the calculator of the device into a predetermined branch branch pipe, it becomes possible to feed an equal amount of pulverized coal to each air blowing tuyere. Furthermore, when it is necessary to change the furnace heat in the circumferential direction of the blast furnace in the operation of the blast furnace, it is necessary to blow a predetermined amount of pulverized coal into a predetermined blast tuyere. This can be achieved by introducing a gas amount into a predetermined branch branch pipe, stabilizes the furnace heat management of the blast furnace at a high level, and enables smooth blast furnace operation.

[Brief description of drawings]

FIG. 1 is a system diagram showing an embodiment of a pulverized coal injection distribution control device for a blast furnace according to the present invention, and FIG. 2 is a graph showing quantitatively the relationship between distribution ratio and added gas relative amount according to the present invention. FIG. 3 is a system diagram showing an example of a pulverized coal blowing device into a conventional blast furnace. In the drawings, 1 is a pulverized coal supply tank, 2 is a disperser, 3 is a pipe, 4 is a single carrier pipe, 5 is a blast furnace, 6 is a distributor, 7a,
7b is a branch pipe, 8a is a blast tuyere, 9a is a burner, 10
a and 10b are additional gas introduction pipes, 11a and 11 are flow rate control valves, 12a and 12 are additional gas flow meters, 13a and 13b are pulverized coal flow meters, 14a and 14b are transmitters, and 15a is an additional gas amount control device. Reference numeral 17 is an arithmetic unit, and 18 is an instruction setter.

Claims (1)

[Claims] 1. A fine powder that has been conveyed by gas through a pipe flows in from the center of the lower portion of a cylindrical body, and the inlet end is connected to openings provided at predetermined intervals along the inner peripheral surface of the peripheral wall of the cylindrical body. In the distribution device for distributing and flowing out to the branch branch pipe, a device for introducing additional gas from outside the system to the distribution branch pipe and a fine powder flow rate detection device are provided side by side, and the fine powder flow rate before the bad powder flow rate control in each distribution branch pipe is The target fine powder distribution is detected based on the relationship between the relative amount of the additional gas and the fine powder distribution ratio (target fine powder distribution ratio / fine powder distribution ratio before control) that has been detected. Distribution control device for air-delivered fine powder, characterized in that the distribution control device comprises an arithmetic unit for calculating the amount of additional gas required to achieve the above rate for each distribution branch pipe and a control unit for controlling the amount of additional gas based on the calculation result. .