JPS6354612B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to pulverized fuel handling equipment, and in particular to a pulverized fuel handling equipment that allows pulverized coal to be injected into a blast furnace to replace a portion of the coke normally used. This invention relates to a fuel feeding device.

In smelting iron ore in blast furnaces, coke has traditionally been the material used to provide the carbon and also to generate the necessary heat during the smelting process. Coke, which generally accounts for about one-third of the contents in a furnace, is a very expensive and essential item in the production of iron. Therefore, it is important from an economic point of view to replace some of the used coke with cheaper coal.

Various prior art techniques are utilized to inject pulverized coal into blast furnaces, thereby replacing a portion of the coke currently in use with pulverized coal.

The present invention consists of a coal pulverizer that pulverizes and dries coal sent by a coal feeder from a storage container storing lumped coal into fine powder; a storage tank for storing pulverized coal; and distribution means connected to the storage tank and several feed tanks associated therewith, from which the blast furnace receives pulverized coal from the feed tank through pressurized gas transfer means having a disperser and a distributor. The main parts of the pulverized fuel feeding device are as follows.

An inert gas supply pipe is connected immediately upstream of the cut-off valve of the cut-out pipe that connects the pressurized tank and the disperser.

A screen device is provided to allow access to the pulverized fuel passageway connecting the separation device and the storage tank.

A heater was installed in the inert gas supply line for fluidization connected to the storage tank.

Hereinafter, one specific example of the present invention will be described with reference to the accompanying drawings.

In the pulverized coal feeder system 10 illustrated in FIG. do.

A feeder 12 feeds coal to a crusher 14 . The pulverizer 14 functions to convert the coking coal into pulverized coal having a suitable particle size and degree of dryness for transport in fluidized dense phase form into the molten ore furnace 15 .

As shown, an independently fired air heater 16 connected to the crusher 14 by a duct 22 supplies hot primary air to the crusher 14 to dry the coal and then pass it through a pipe 18 to a cyclone-type separator. The produced coal is transported to the inlet of No. 17. Hot primary air is produced by burning coke oven gas which is introduced into the heater 16 through a pipe 19, with the air being passed through the heater 16 by a duct 21.
The primary air blower 20 is connected to the primary air blower 20 .

In order to allow the ratio of the primary air flow rate to be adjusted according to the coal flow rate through the crusher 14, an adjustable air door 20A is attached to the blower 20.

The air-coal mixture entering the cyclonic separator 17 is centrifuged and the coal passes by gravity fall through a line 24 to a storage tank 23, which line is provided with a normally open shutoff valve 25.

The very fine coal particles entrained in the primary air, as they leave the separator 17, are carried along with the air through the pipe 26 to the bag filter chamber 27 and are collected therein. The primary air flow is vented to a low pressure chamber (not shown) and the collected micropulverized coal is collected in line 2 with a normally open isolation valve 29.
8 to the storage tank 23.

During the comminution and storage period, the moisture evaporated from the coal surface is exhausted along with the primary air.

Storage tank 23 is suitably vented to operate at atmospheric pressure and serves to provide storage of sufficient pulverized coal to supply a plurality of patch tanks 31A, 31B, and 31C leading to furnace 15.

The tanks 31A-C are located at a lower level than the storage tank 23, and a plurality of coal distribution lines 3 are connected thereto.
They are connected by 0A to C, respectively.

Remotely operable shutoff valves 32A, 32B, and 32C are attached to distribution lines 30A-C.
The tanks 31A to 31C are connected to the corresponding coal discharge pipe 34.
It is placed in communication with the pneumatic transfer line 33 by A to C. The discharge line includes a furnace 15 through line 33.
a discharge tank that is selectively opened to allow the flow of coal grains from one selected tank 31A-C at a time, and simultaneously closed to isolate tanks other than the currently selected tank from conduit 33. Coal flow control valves 35A-C are each installed.

A distributor 70 is interposed in the transfer line 33 and is supplied with the compressed air necessary for the pneumatic conveyance of the coal by the compressed air source 36 . The outlet of the compressed air source is connected to line 33 through a control valve 37 and a check valve 38. In the melting furnace 15, the conduit 33 communicates with one or more distributors 39 and from there a number of coal supply pipes 40, as described in U.S. Pat.
It leads to the individual tuyeres 41 of the furnace 15 in the same manner as described in 3150962 and 3204942. The number of distributors 39 as well as the number of tuyeres used by each distributor will vary depending on the requirements of the melt furnace 15.
Each of the pipes 40 is provided with a nozzle 42 extending through a tuyere 41 and
The blast air is opened directly into the furnace 15 and is introduced through the tuyeres 41 in order to rapidly mix the coal and blast in the furnace 15, thereby promoting rapid and complete combustion. supply pulverized coal directly to

Inert gas is used to pressurize tanks 31A-C and also to fluidize the coal contents of tanks and storage tank 23. For this purpose,
Even when the compressed gas source 50 is at the maximum expected furnace demand,
Sufficient transfer pressure is provided to maintain dense coal flow from a given tank 31A-C to transfer line 33 against the maximum expected back pressure of furnace tuyere 41. Tuyere back pressure can reach pressures as high as about 4.5 Kg/cm ² and is caused by the high static pressure in the annular tube 51 that supplies the required process air to the furnace through the tuyere 41. Selecting an inert gas for pressurization and fluidization is preferred because it prevents coal from igniting in storage tank 23 and tanks 31A-C.

Valves 32A-C and discharge coal flow control valves 35A-C
In addition, tanks 31A-C are equipped with valves 52A-C, 53A-C, and 54, respectively, to achieve the required pressurization, fluidization, venting, and pressure equalization functions.
A to C, and 55A to C are provided. The pressurizing valves 52A to 52C are connected to the compressed inert gas source 50 through a check valve 56 and a control valve 57 by appropriately arranged piping, and are connected to the respective tanks 3.
1A-C and serves to pressurize the coal contents of the tank when the valve opens. The fluidization valves 53A-C are connected to the respective tanks 31A-C.
and a valve 52A to the compressed gas source 50.
Inert gas is introduced into the lower portions of tanks 31A to 31C connected in parallel with tanks 31A to 31C, and the coal inside is fluidized with the gas. Valve 54 functions to vent each tank 31A-C to a suitable receptacle or chamber (not shown) upon opening.

The valves 55A to 55C are connected to the storage tank 23 via appropriate conduits.
and are connected to the respective tanks 31A to 31C, and function to equalize the pressure between the tanks 31A to C and the storage tank 23 upon opening, and the tanks 31A to
Exhaust pressure and closure are operated to maintain the pressure inside C at a predetermined pressure. The coal contents in the storage tank 23 are fluidized with an inert gas flowing through a conduit connecting the storage tank 23 and a gas source and comprising a control valve 60 and a check valve 61. In operation of system 10, each of tanks 31A-C is alternately filled, pressurized, and emptied to deliver pulverized coal to furnace 15 in a predetermined cycle sequence.

When pulverized fuel, ie, pulverized coal, is continuously injected from the blast furnace's blast furnace tuyere using a pulverized fuel feeding device configured in this way, the following three problems sometimes occur, which hinders smooth operation. .

One of them is that the coal discharge pipes 34A and 34B are connected to the tanks 31A, B, and C, which repeat the operations of filling, pressurizing, waiting, and blowing, as shown in FIG. , C are compressed and tightly packed to block the pipes 34A, B, and C, making it impossible to cut them out for subsequent blowing.

The next problem is that iron pieces, metal pieces, wood pieces, vinyl membranes, scrap wool, etc. are mixed into the coal. Among these contaminants, iron pieces and metal pieces are removed by respective removal devices, and wood pieces are crushed by a crusher 14 and reduced to a size that does not become an obstacle. However, there is no effective means for removing vinyl membranes and waste wool, so they are transported to the separation device along with the crushed pulverized coal, and cannot be moved in the coal conveyance pipe where the diameter of the pipe becomes smaller, resulting in clogging of the pulverized coal. coal transportation will be interrupted.

Yet another problem is the increased cost due to raw coal. Normally, pulverized coal is sent to the separator 17 while being dried with high-temperature air, so its moisture content is approximately 1/2 of the inherent moisture content of the coal.For example, coal with an inherent moisture content of 10% has a moisture content of approximately 5%. Become.

When pulverized coal is stably blown into a blast furnace, unless the moisture content is maintained at 2% or less, problems such as pulsating flow and blockage of pipes will occur.

Therefore, when selecting a brand of coal, choose one with an inherent moisture content of 4% or less.
Coal that falls within this range is a high caking coal with a high unit price, while thermal coal with a low unit price and poor caking properties has an inherent moisture content of far more than 4%, making it unusable and making it difficult to use as pulverized coal in blast furnaces. The economic efficiency of the charcoal injection furnace operation method deteriorates.

The present invention was made to solve these problems and improve the practicality of the blast furnace operation method using pulverized coal injection. A coal pulverizer that pulverizes and dries the coal sent by the feeder into fine powder; A hot air generator that feeds a high-temperature conveying medium through the pulverizer; A mixture of both the pulverized fuel and the conveying medium from the pulverizer; a separation device that separates the fuel; a storage tank that receives the pulverized fuel separated by the separation device; a storage tank provided at a lower position of the storage tank;
A pressurized tank that allows the pulverized fuel to selectively fall by gravity; and a conveyance and distribution device that transfers the pulverized fuel from the pressurized tank to a blast furnace using an inert gas through a disperser and a distributor. In the pulverized coal feeding device, guides 85A and 85B are provided on the lower side of the separator 17, and guides 85A and 85B that can guide screens 83A and 83B in and out are provided over the entire cross section of the lower pulverized coal falling flow path. Moving cylinders 86A and 86B are provided, and a seal valve 82 is provided in the communication portion between the guide and the lower side of the separation device.
A, 82B are arranged and the pressurized tanks 31A, 31
Coal discharge pipe 34 connecting B, 31C and the disperser
Coal flow control valves 35A, 35 of A, 34B, 34C
A pipe line 74 for supplying inert gas is connected immediately upstream of B and 35C, and this inert gas supply pipe line 74
A, 74B, 74C have check valves 71A, 71B, 7
1C, and at least on the upstream side of the coal flow control valve, flowing inert gas having a pressure higher than the internal pressure of the pressurized tank is supplied to the coal discharge pipe 34A,
34B, 34C, the pressure setting valve 72 is adjacent to the automatic opening/closing valve 72A, 72B, 72C, or the orifice θ is adjacent to the differential pressure constant flow control valve 72A',
This is a pulverized fuel feeding device characterized by interposing 72B' and 72C'.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings. Figures 2A and 2B show a configuration for solving the first problem, in which coal discharge pipes 3 leading to coal flow control valves 35A, B, and C of batch tanks 31A, B, and C are shown.
A pipe line 74 connected to a nitrogen source (not shown) through check valves 71A, B, C and fluidizing valves 72A, B, C is provided in 4A, B, and C, and at least nitrogen gas for fluidization is supplied to While the coal flow control valves 34A, B, and C are closed, the batch tank (pressure tank) 31A,
Coal discharge pipe 34 at a pressure higher than the pressures of B and C
By sending the pulverized coal into A, B, and C and flowing it to the batch tank side, the pulverized coal remaining in the coal discharge pipe is made to float and flow in the coal discharge pipe, thereby reliably preventing clogging.

The fluidization valves 72A, B, and C have a constant pressure setting type valve configuration,
That is, as shown by the dotted line in FIG.
Only when coal flow control valves 35B and C are closed during filling, pressurization, and standby periods are A, B, and C adjacent to each other, a pressure setting valve 72 is set to a predetermined pressure that exceeds the maximum value of the pressure change in the batch tank during this period. It may be configured with an automatic opening/closing valve that opens only when the tank is closed, or it may be configured with an orifice θ adjacent to it, as shown by the dashed line in Fig. 2A, and operated at a predetermined differential pressure between the two at all times, so that the control pressure value in the batch tank is controlled. Any of the so-called well-known differential pressure-operated differential pressure constant flow control valves that always flow a constant flow rate of inert gas even if the valve is changed is used. In each of the batch tanks (pressurized tanks) 31A, B, and C, fluidizing inert gas is always flowed into the lower part from the valves 53A, B, and C, as described above, and the batch tanks (pressurized tanks) 31A, B, and C are constantly supplied with inert gas for fluidization through the valves 53A, B, and C, and are not injected, depressurized, filled, or pressurized. The pressure inside the pressurized tank during the standby period is determined by each of the above-mentioned valves 52A-C, 53A-C, 54A-C, 5.
4, 55A to 55C, the coal discharge pipes 34A, B, and C are automatically controlled to the desired pressure even during the pressurization period.
As described above, inert gas can be introduced into the pressurized tank through the pipe 74 without compacting the pulverized coal in the coal discharge pipe.

Figures 3A, 3B, and 3C show a configuration for solving the second problem.
A and B are connected and mounted movably within guides 85A and B, and further air cylinders 86A and B are provided so that the screens 83A and B can be taken in and out of the separator 17 using the operating rod 81. Seal valves 82A and 82B are provided in the movement path to prevent leakage of the pulverized coal flow.

Figure 4 A and B are other examples of the screen 8 in Figure 3.
3A is movable as in the example shown in FIG. 3, and a screen 83B is fixedly installed inside the separator 17. FIG. 5 shows a configuration to solve the third problem, in which steam, hot air, an electric heater, etc. are connected to the pipe line that supplies nitrogen, which is a fluidizing gas, to the storage tank 23 via a check valve 61 and a control valve 60. A heater 90 is provided for heat exchange heating using a heat source.

FIG. 6 shows an example of implementing each of the measures described above.

Since the present invention is constructed as described above, it is possible to continue supplying pulverized coal stably and smoothly to the blast furnace blowing tuyere, and the practicality of the pulverized coal injection blast furnace operation method has been dramatically improved.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the conventional example, Figure 2 A and B are explanatory diagrams showing the configuration of the problem countermeasure in the batch tank and the operating state of the countermeasure valve, Figure 3 A, B, and C, and Figure 4 I , B shows the configuration of problem countermeasures in the separator, A is a side view, B and C are plan views, FIG. 5 is a side sectional view showing the configuration of problem countermeasures in the storage tank, and FIG.
The figure is an explanatory diagram showing one example of implementing the present invention. 74 is a fluidizing gas supply pipe, 83 is a screen, and 90 is a heater.

Claims (1)

[Claims] 1. A coal pulverizer that pulverizes and dries coal sent by a coal feeder from a storage container storing lumped coal into fine powder: A hot air generator that feeds a high-temperature conveying medium through the pulverizer: From the pulverizer A separation device for separating both a mixture consisting of a pulverized fuel and a carrier medium; A storage tank for receiving the pulverized fuel separated by the separation device; A storage tank provided below the storage tank, where the pulverized fuel is selectively separated by gravity. A pulverized fuel feeding device comprising: a pressurized tank that allows the pulverized fuel to be lowered; and a conveying and distribution device that transfers the pulverized fuel from the pressurized tank to a blast furnace through a disperser and a distributor using an inert gas. , Guides 85A, 85B that can guide screens 83A, 83B in and out are provided on the lower side of the separator 17 over the entire cross section of the lower pulverized coal falling channel, and screen moving cylinders 86A, 86B are provided. Coal discharge pipes 34A, 34B, and 34C are provided with seal valves 82A and 82B in the communication portion between the guide and the lower side of the separator, and connect the pressurized tanks 31A, 31B, and 31C to the disperser. A conduit 74 for supplying inert gas is connected immediately upstream of the flow control valves 35A, 35B, 35C, and a check valve 71 is connected to the inert gas supply conduit 74A, 74B, 74C.
A, 71B, 71C are provided, and at least the coal flow control valve is provided on the upstream side thereof, and only when the coal flow control valve is closed, a pressure that sends flowing inert gas having a pressure higher than the internal pressure of the pressurized tank to the coal discharge pipes 34A, 34B, and 34C. Automatic opening/closing valves 72A, 72B, adjacent to the setting valve 72,
A pulverized fuel feeding device characterized in that differential pressure constant flow control valves 72A', 72B', and 72C' are provided with adjacent orifices 72C or orifices θ.