KR20030023384A - Vented gas recovery method in a pulverized coal conveying system - Google Patents

Abstract

PURPOSE: Provided is a recovering method of an emission gas in a transfer facility of pulverized coal which is capable of recovering an inert gas to be emitted to the atmosphere after finishing transfer of a pulverized coal in a transfer facility of a high concentration pulverized coal to utilize it for compressing another feeder hopper. Thereby, the waste of the expensive inert gas can be reduced and the amount of the emitted gas is minimized to prevent the air pollution. CONSTITUTION: The recovering method of an emission gas in a transfer facility of pulverized coal comprises a step of pressurizing the interior of a feeder hopper under the pressure by recovering the emission gas, nitrogen gas from an exhaust pipe mounted on top of a feeder hopper under the back pressure in the transfer facility of pulverized coal, to a charge pipe mounted on top of a feeder hopper under the pressure, through a connecting piping; and a step of fluidizing an amount of nitrogen gas from upper side to lower side through the bottom side of the feeder hopper under the pressure at the same time with the pressurizing step.

Description

VENTED GAS RECOVERY METHOD IN A PULVERIZED COAL CONVEYING SYSTEM}

The present invention is another feeder by recovering the inert gas released into the atmosphere after the completion of the transfer of pulverized coal in a facility that transfers pulverized coal to a high concentration of pulverized coal (hereinafter referred to as "meat ratio") to the weight of the solid to the weight of the gas to be transported (hereinafter referred to as "meat ratio") The present invention relates to a method for recovering exhaust gas from a pulverized coal transport facility that can be utilized for pressurizing a hopper.

As shown in FIG. 1, a facility for transporting pulverized coal having a high concentration of meat of 10 or more to steel blast furnace is a storage hopper (STORAGE HOPPER) 10 in which pulverized coal is stored; A plurality of feeder hoppers 20, 30, and 40, which are charged with high-pressure pulverized coal stored in the storage hopper 10; The powdered coal transported from the feeder hopper (20, 30, 40) is divided into several strands (approximately 20-40 strands) along the outer circumferential surface of the blast furnace is composed of a distributor (50).

The feeder hopper (20, 30, 40) is a charging process to receive the pulverized coal from the storage hopper 10, a pressurization process and a transfer standby process to add pressure to the charged pulverized coal, a transfer process for transferring the pulverized coal to the blast furnace, filling In order to go through a back pressure process to lower the pressure inside the feeder hopper (20, 30, 40), the pulverized coal conveyed to the blast furnace is to be continuously supplied, as shown in the three feeder hopper (20, 30, 40) Will work as a set. That is, while feeder # 1 transfers pulverized coal, feeder hopper # 2 is pressurized and waits for delivery, and feeder hopper # 40 is backpressured and charged to 1 → 2 → 3 →. 1 → .... continue to transfer pulverized coal to the blast furnace.

When transferring the pulverized coal from the feeder hopper (20, 30, 40), the gas is blown to the lower end of the feeder hopper (20, 30, 40) (hereinafter referred to as "FLUIDIZING") to pulverize the pulverized coal When pressurized, high pressure gas is introduced into the pulverized coal-filled layer, and back pressure is discharged into the atmosphere through a valve and a bag filter installed on the feeder hoppers 20, 30, and 40.

The inert gas released (usually "nitrogen") is very expensive at the time of release because it is expensive and is a major cause of air pollution, so it is required to reduce the amount of possible emissions.

In this process, when pressing the feeder hopper 20, 30, 40 without much consideration, the pulverized coal-filled layer is easily compacted, and as a result, the transfer becomes difficult. Therefore, the pulverized coal is compacted by installing a plurality of pressurized pipes 100 along the lower circumferential surfaces of the feeder hoppers 20, 30, and 40 and simultaneously supplying a high pressure gas through the pulverized coal. Fixation) as much as possible.

Conventionally, a plurality of holes are formed in a portion of the outer peripheral surface of the lower end of the feeder hoppers 20, 30, and 40 separately from the pressure pipe 100 installed in the feeder hoppers 20, 30, and 40 to recover the gas discharged. By connecting to the back pressure pipe 110 provided on the top of the other feeder hopper (20, 30, 40) to recover the gas released during the back pressure process of one feeder hopper to be used for pressurizing the other feeder hopper. .

However, manufacturing a plurality of holes in the feeder hopper, which is a pressure vessel, causes a safety problem. Also, since a large amount of fine coal particles exist in the back pressure gas, a backflow prevention filter (pulverized coal from the feeder hopper) installed at the end of the pressurized pipe 100 is provided. The porous material to prevent the reverse flow of gas to prevent the passage of large solid particles) easily blocked, there was an inconvenience to install a separate device in the middle of the pipe for the recovery of pulverized coal contained in the gas.

The present invention was created in order to effectively improve the above-described problems in the prior art as described above, by connecting the high-pressure gas discharged from one feeder hopper to the upper side of the other feeder hopper feeder hopper the other feeder hopper It is an object of the present invention to provide a method for recovering the exhaust gas from a pulverized coal transport facility, which can be recovered and used while maintaining the pulverized coal charged therein.

1 is a schematic configuration diagram of a general pulverized coal transport facility;

Figure 2 is a schematic cross-sectional view showing the feeder hopper of the pressing process of the conventional pulverized coal transport facility and its perspective view,

Figure 3 is a cross-sectional view of the operating state showing the exhaust gas recovery process for explaining the method of the present invention.

Explanation of symbols on the main parts of the drawings

20,30,40: feeder hopper 50: distributor

100,100 ': Pressurized pipe 110,110': Back pressure pipe

120,120 ': Filling pipe 140,140': Transfer pipe

150,160: Branch pipe 200: Connection pipe

210,220: On-off valve

The above object of the present invention is to recover the nitrogen gas of the discharge gas from the discharge pipe installed on the top of the feeder hopper in the back pressure of the equipment for conveying pulverized coal to the filling pipe installed on the top of the feeder hopper under pressure through the connecting pipe Pressing the feeder hopper in a pressurized state; By providing a method for recovering the exhaust gas in the pulverized coal transport facility, comprising the step of pruding a certain amount of nitrogen gas from the lower side to the upper side through the bottom surface of the feeder hopper in the pressurizing process simultaneously with the pressurizing process. Is achieved.

Hereinafter, with reference to the accompanying drawings will be described in more detail the exhaust gas recovery method of the present invention.

3 is a schematic cross-sectional view showing a recovery method according to the present invention.

Referring to FIG. 3, the present invention provides a separate connection pipe 200 for communicating a portion of the upper end of each feeder hopper and a pair of first and second opening / closing valves 210 and 220 to control the opening and closing of the connection pipe 200. It is installed at both ends to recover the nitrogen gas released during back pressure and to be used as pressure gas for the other feeder hopper.

That is, the first branch pipe 150 is formed at a part of the filling pipe 120 communicatively disposed at the upper end of the first feeder hopper 10 and the back pressure pipe 110 disposed at the upper end of the second feeder hopper 30. The second branch pipe 160 is formed at a part of ').

Here, the filling tube 120 is a tube that receives the pulverized coal from the storage hopper 10.

These first and second branch pipes (150, 160) are connected by a connection pipe 200, the first and second opening and closing valves 210 and 220 are respectively provided at both ends of the connection pipe (200).

In this manner, the feeders hoppers 1, 2, 3, 20, 30, and 40 are communicated with each other to recover a part of the nitrogen gas released and reuse it.

The lower outer circumferential surface of each feeder hopper (20, 30, 40) is provided with a pressurizing pipe (100, 100 ') and a transfer pipe (140, 140') of the same structure as the existing, the lower surface of the feeder hopper (20, 30, 40) A plurality of fluidizing nozzles 130 are installed.

Referring to the method for recovering the exhaust gas in the pulverized coal transport facility having such a configuration as follows.

Prior to the description, when the third feeder hopper 40 is back pressure (approximately 13 bar g → 0 bar g), the second feeder hopper 30 is subjected to the pressurization (0 bar g → 13 bar g) at the same time, the third feeder hopper When the gas of 40 is connected to the feeder hopper 30 before the gas is discharged into the atmosphere, the high-pressure gas is introduced into the feeder hopper 30, and the pressures of the two feeder hoppers 30 and 40 become uniform. Until the gas inflow from the third feeder hopper 40 to the second feeder hopper 30 continues.

As a result, about 50% of the amount of gas used when pressurizing the second feeder hopper 30 can be used to recover the gas discharged from the third feeder hopper 40 to the atmosphere.

The method for recovering the exhaust gas includes a feeder hopper 2 through a connecting pipe 200 connected to the gas discharged at the back pressure of the first feeder hopper 20 through the filling pipe 120 of the first feeder hopper 20 ( The back pressure pipe 110 ′ of 30) is introduced into the feeder hopper 30.

At the same time, the discharged gas is pressurized inside the feeder hopper 30 at the bottom of the feeder hopper 30 so that the pulverized coal layer in the second feeder hopper 30 pressurized due to the released gas is not compacted. Through the 130 is to perform the fluidizing.

Subsequently, the pressures of the two feeder hoppers 20 and 30 are the same, and the first and second open / close valves 210 and 220 are closed when there is no more gas inflow between the feeder hoppers 20 and 30. After completely blocking the 2nd feeder hopper 30 was carried out at the bottom of the fluidization is also stopped.

The fluidizing should only be operated at the inlet of the exhaust gas, its vertical velocity should be faster than the minimum fluidization velocity (MINIMUM FLUIDIZING VELOCITY = vmf) and can be adjusted from at least 2 to up to 20 times depending on the humidity or particle size of the pulverized coal. Handfulness is preferred.

When the diameter of pulverized coal is 50 μm, the density is 1400 kg / m 3, and the used gas is nitrogen and the pulverized coal humidity content is less than 1%, the minimum fluidization rate vmf is about 0.001 m / s.

When the volume of gas in the feeder hopper is 45 m 3, pressurized to 13 bar g, and it takes about 10 seconds to reach 0 → 6.5 bar g due to the pressure of the discharge gas, one feeder hopper reaches 6.5 bar g The total amount of gas needed until pressurized

; Where V _FH is the volume in the feeder hopper to be filled (45 m 3) and P _C is the pressure upon compression in the feeder hopper, i.e. the pressure until both feeder hoppers are in equilibrium, so 13bar g / 2 = 6.5 bar g (gage ), P _N is 1 since NORMAL pressure, and ρ _N is 1.25 kg / m 3 as the density per volume of nitrogen gas.

Therefore, Q = 45 X (6.5 + 1) X 1.25 = 421.875 kg is calculated, so a total of 421.875 kg is required,

The feeder hopper 30 for 10 seconds is pressurized if the speed is 3 times the minimum fluidization speed and the fluidizing takes place evenly at the bottom of the second feeder hopper 30 having a diameter D of 900 mm. The amount of gas flowing through the bottom of the

Because of;

When calculated in the same manner as the calculation of the total gas amount during the pressurization, about 0.2kg of gas flows into the feeder hopper No. 2 by the fluidizing, the remaining 421.675kg is the feeder hopper No. 1 20 It is proved that the gas from the release of can be used.

Therefore, it can be seen that the reduction of the inflow amount of the emitted gas generated by the fluidizing is not so large.

In the present invention, the gas discharged from the other feeder hopper is allowed to flow from the upper portion of the feeder hopper through the filling tube and at the same time, it is possible to suppress the pulverized coal is compacted because it is carried out only at the moment of inflow. As described above, since the amount filled with the feeder hopper by the pluding is not so large, it is possible to sufficiently increase the pluding speed to a range that can suppress the pulverized coal compaction.

In addition, in the present invention, the discharge pipe of one feeder hopper and the filling pipe of the feeder hopper are connected to each other in order to recover the discharge gas. However, even when passing through the discharged gas using a relatively large diameter pipe compared to other pipes connected to the feeder hopper, there is no problem such as clogging due to the pulverized coal contained in the gas. This is because it can be used without forming a hole.

As described in detail above, the present invention provides the following effects.

First, it is possible to reduce the waste of expensive inert gas by recovering the gas discharged during the pulverized coal transport and use in the pressurization process of other feeder hopper.

Second, it provides an effect of preventing air pollution by minimizing the amount of emitted gas.

Third, it is possible to improve the pulverized coal collecting capacity and to extend the life of the bag filter.

Claims (4)

Nitrogen gas, which is the discharge gas, is discharged from the discharge pipe installed at the top of the feeder hopper in the back pressure state to the filling pipe installed at the top of the feeder hopper in the pressurized state through the connecting pipe in the feeder hopper under the pressurized state. Pressurizing the process; And exhausting a predetermined amount of nitrogen gas from the lower side to the upper side through the bottom surface of the feeder hopper in the pressurizing process simultaneously with the pressurizing process. The method of claim 1, wherein in the process of recovering and pressurizing the discharged gas, pressurizing only until the internal pressure of the feeder hopper in the back pressure and the feeder hopper in the pressurized state becomes equal. . The method of claim 1, wherein in the fluidizing process, the fluidizing speed is varied by 2 to 20 times the minimum fluidization rate according to the humidity or particle size of the pulverized coal. . The method of claim 1, wherein the fluoridation process is performed only when the exhaust gas is recovered to pressurize the inside of the feeder hopper in a pressurized state.