JPS6230242B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blast furnace exhaust gas treatment facility that efficiently removes dust from blast furnace exhaust gas to produce clean gas and utilizes the energy contained in this clean gas.

In conventional blast furnace exhaust gas treatment equipment, the blast furnace exhaust gas is at high temperature (around 100 to 200 degrees Celsius) and high pressure (around 1 to 3 atm) and contains dust of about 10 g/Nm ³ , so the dust content is reduced to 5 to 5. After removing dust to reduce the amount to about 10 mg/Nm ³ , the energy held in the gas is recovered, and the gas after energy recovery is stored and used again as blast furnace gas.

However, conventional processing equipment has problems such as low collection efficiency of the dust collector used and inability to perform continuous dust collection.

That is, conventionally used dust collectors include wet type and dry type. In the wet dust collection method, dust is removed by bringing gas cleaning water into contact with the dust-containing gas, but as the water evaporates, the amount of gas increases, and as a result, downstream equipment becomes larger. Since the recovered gas contains moisture, the calorific value per unit capacity is small, and since the gas is cooled to about 60°C, there is a problem that the sensible heat of the blast furnace exhaust gas cannot be effectively recovered. In this regard, the dry dust collection method uses a layer of abrasion-resistant filter material such as sand to form the dust collection section, which removes dust with high performance and low pressure loss, allowing clean gas to remain at high temperature and high pressure. Because it can be removed, it has recently come to be used in place of wet dust collection methods.

In the dry dust collection method, the drop in gas temperature, calorific value, and pressure is smaller than in the wet dust collection method, so if it is used to treat a large amount of blast furnace exhaust gas containing dust at high temperature and high pressure, it is possible to use energy effectively. I can understand that.

However, in conventional dry dust collectors, a wear-resistant filter material such as sand or gravel is filled between vertically arranged wire mesh or perforated metal plates, and this is moved continuously or intermittently. When the gas flowing in the horizontal direction passes through a layer of filter material, the dust in the gas is collected, and the collected dust is moved together with the filter material and then separated from the filter material. ,
A cylindrical body using a wire mesh or metal perforated plate as the bottom plate is filled with an abrasion-resistant filter material, and the filled layers are disposed intermittently in the circumferential direction to form spaces for settling dust between the filled layers. There are some known devices that are equipped with a rotatable blower pipe that blows air below the packed bed, and the dust that is collected when the gas passes through the packed bed is made to float by the head wind that blows up the packed bed. There is.

However, in the dust collector, the filter material is moved from top to bottom, so when the collected dust moves from top to bottom together with the filter material, it moves not only downward but also to the gas downstream side. Therefore, the dust once collected flows out to the downstream side of the dust collector together with the gas, and the collection efficiency decreases. In order to increase the collection efficiency, it is necessary to make the packed bed multi-layered, which causes problems such as the equipment becomes large-sized and a means for moving and circulating the filter medium is also required.

The dust collector is designed to discharge dust suspended by air blowing up the packed bed from the outside by settling it downward from the dust settling space arranged in the circumferential direction. There are problems such as the fact that dust cannot be discharged quickly, that a blower pipe is required to introduce air from outside, and that continuous gas purification cannot be performed due to the presence of a space for dust to settle.

The present invention efficiently collects dust from a large amount of blast furnace exhaust gas containing dust, actively and continuously collects the collected dust along with the gas for further dust removal, and effectively recovers the energy contained in the clean gas. A container that has a gas inlet at the top and a clean gas outlet at the bottom so that gas flows from the top to the bottom, and a vertical coarse duct installed in the center of the container. a coarse dust collector connected above the coarse particle duct and having an inverted conical hopper with a large diameter at the upper end, which receives coarse particles removed by its own weight from the gas traveling in the upper part of the container; A rotatable rotary cylinder is arranged concentrically around the outer periphery of the grain duct, and the rotary cylinder is arranged below the coarse dust collector hopper in the container and is filled with a filter material such as sand. a horizontal annular packed bed, a cleaning hood disposed above the packed bed that suspends and suctions dust collected in the packed bed by gas flowing back through the packed bed from below, and one end of which is connected to the cleaning hood; A dry type dry type comprising a particulate duct connected to the rotating cylinder and having the other end fixed to the rotating cylinder, and a suction gas pipe arranged at the bottom of the rotating cylinder and sucking gas and dust introduced from the cleaning hood through the particulate duct. a dust collector; a cyclone dust collector that separates dust from the gas sucked from the suction gas pipe; a bag filter that further removes dust from the gas removed by the cyclone dust collector; a suction gas cleaning device equipped with a blower that sucks clean gas; a turbine driven by the clean gas introduced from the clean gas outlet of the dry dust collector and the suction gas cleaning device; and a turbine rotated by the turbine. The present invention is characterized by being provided with an energy recovery section equipped with a generator.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the entire blast furnace exhaust gas treatment equipment of the present invention. The blast furnace exhaust gas treatment equipment of the present invention can be roughly divided into two parts:
a dry dust collector that dryly collects dust from exhaust gas introduced through the dry dust collector, a suction gas purifier that purifies the gas by sucking the dust collected by the dry dust collector together with gas, and the suction gas purifier. It consists of an energy recovery unit that recovers energy from the gas from the device and the gas cleaned by the dry dust collector, and the clean gas from which the energy has been recovered is stored in the gas holder 3.

An example of the dry type dust collector is constructed as shown in FIG. 2 in detail. That is, there is a gas inlet 6 at the top.
A coarse particle duct 9 having a large-diameter hopper constituting a coarse dust collector 8 at the top is provided in the center of the container 5, which has a clean gas outlet 7 at the bottom, and a coarse dust collector 8 in the container 5. On the downstream side of the container 8, a packed bed 10 is formed by using a wire mesh, a metal perforated plate, etc. 11 as a bottom plate, and is filled with an abrasion-resistant filter material 12 made of grains of sand or the like and having a substantially uniform particle size, thereby forming a filter dust collection system. 10' are disposed in two stages, upper and lower, in the circumferential direction, and the filled layers 10, 10' are partitioned into a plurality of layers in the radial direction by partition plates 13,
As shown in Fig. 3, a large number of partition plates 1 extend radially.
At 3', there are many partitions in the circumferential direction, and the filled layer 1
0,10' are each divided into a number of adjacent chambers,
The gas on the upstream side always passes through the packed beds 10, 10'.

A rotary cylinder 14 is arranged concentrically on the outside of the coarse grain duct 9, and the coarse grain duct 9 is made airtight by a gas seal 15.
Upper and lower two-stage box garter 1 that supports 0'
6, 16' and the lower surface of the container 5, the gas seal 17
The rotary cylinder 14 is made airtight through the holder, and the rotary cylinder 14 can be rotated while maintaining airtightness. Regarding the rotation of the rotary cylinder 14, the upper part of the rotary cylinder 14 is guided by a guide roller 18 attached to the upper box girder 16, and a rail/gear 19 attached to the outer periphery of the lower end of the rotary cylinder 14 is connected to the container 5. The rotary cylinder 1 is received by a guide roller 20 attached to
4 can be rotated. This rotating cylinder 14
For this purpose, fine grain ducts 23, 23' corresponding to the upper and lower filling beds 10, 10' are fixed at multiple locations on the circumference, and fine particle ducts 23, 23' corresponding to the upper and lower filling beds 10, 10' are fixed at multiple locations on the circumference, and fine particle ducts 23, 23' are fixed on the upstream side of the packed beds 10, 10', that is, on the upper surface of the packed beds. In addition, cleaning hoods 24, 2 whose number and size correspond to the number and size of the compartments in the radial direction.
4', and each cleaning hood 24 on the upstream side of the upper packed bed 10 (the one corresponding to the radially outer packed bed part is shown in FIG. 2) is connected to the Each is connected to the fine particle duct 23,
Similarly, each cleaning hood 24' located upstream of the lower packed bed 10' (the one corresponding to the radially inner packed bed part is shown in FIG. 2) is also fixed to the lower part of the rotary cylinder 14. Connected to the fine particle duct 23', the upper and lower cleaning hoods 2 are
4, 24' can be rotated. Note that the cleaning hoods 24, 24'
0', and has skirts 25 on the front and rear sides in the direction of rotation, as shown in FIG. Even if the cleaning hoods 24, 24' straddle the packed bed portions of the small chambers adjacent to each other in the circumferential direction, suction can be performed. The cleaning device is connected to the suction gas pipes 26, 26', and the coarse particle duct 9 is similarly connected to the suction gas pipe 26''. 27 is a heat storage device provided as necessary, and the coarse dust collector 8 is This is to equalize the temperature of the gas passing through it. 28 is a telescopic tube.

Next, the above-described suction gas purifying device includes a cyclone dust collector 29, a bag filter 30, and a blower 31. The cyclone dust collector 29 is
As shown in FIG. 5, the hopper bin 3 on the leg 32
At the top of 3, the suction gas pipe 2 of the dry dust collector is installed.
Cyclone 34, 3 connected to 6, 26', 26''
5, 36, so that the gas to be sucked enters each cyclone 34, 35, 36 from a tangential direction to form a swirling flow, and each cyclone 34, 3
5 and 36, a gas pipe 37 is connected to the top to introduce the gas from which dust has been separated into the bag filter 30,
In addition, each cyclone 3 is installed at the bottom of the hopper bin 33.
4, 35, and 36 have a dust cutting section 38 separated from the gas.

As shown in FIG. 6, the bag filter 30 is for further removing dust from the gas that has been removed by the cyclone dust collector 29, and the blower 31 is for sucking the clean gas that has been removed by the bag filter 30. The clean gas is guided to the energy recovery section through the clean gas pipe 4.

Furthermore, the energy recovery section is a gas turbine 39 in this embodiment, and includes a clean gas pipe 40 connected to the clean gas outlet 7 for introducing clean gas from the dry precipitator, and a clean gas pipe 40 for the suction gas cleaning device. The gas pipe 4 is connected to the inlet side of the turbine 39, and the energy recovery turbine 39 is rotated by the pressure and temperature energy possessed by the clean gas, so that energy can be effectively recovered.

In addition, 41 is a generator, 42 is a septum valve,
It functions to reduce pressure and guide gas to the gas holder 3 when the turbine 39 is not rotating.

Since the blast furnace exhaust gas treatment equipment of the present invention has the above-described configuration, when the exhaust gas is introduced from the top of the blast furnace 1 into the container 5 of the dry dust collector from above, it first passes through the coarse dust collector 8. Due to the presence of the gas, the gas is forced to flow laterally and proceed downstream. Due to the gas flowing at this time, coarse dust (iron ore, approximately 200 microns or more) falls into the hopper of the coarse dust collector 8 due to its own weight. The gas from which coarse dust has been removed by the gravity dust collection method passes through the packed beds 10 and 10' in this order and is purified.

Since the packed bed 10 is formed continuously in the circumferential direction, the gas always passes through the filter material 12 of the packed bed 10 and also passes through the lower packed bed 10', and at this time, the dust is removed from the packed bed 10, 10. The gas collected and purified is discharged from the gas outlet 7 to the outside of the container 5 through a clean gas pipe 40, and is led to the energy recovery section.

The cleaning hoods 24, 24' on the upstream side of each packed bed 10, 10' are slowly rotating together with the rotary cylinder 9 rotated by the drive device 21, and the upper surface is covered with the cleaning hoods 24, 24'. Filled layer 1
In each of the small chambers 0 and 10', the inside of the hoods 24 and 24' is under negative pressure due to the suction by the blower 31, so a part of the gas that has passed through the packed beds 10 and 10' flows through each packed bed. A fluidized bed is created by counter-flowing from the bottom to the top. As a result, where the cleaning hoods 24, 24' are located, the dust collected and deposited on the packed beds 10, 10' is suspended by the gas flowing back (the third
Figure shows floating state). In this way, as the cleaning hoods 24, 24' move, the packed beds 10, 10' are continuously fluidized, and the floating dust is sucked by the cleaning hoods 24, 24', and fine particles are collected together with the fluidized gas. Suction gas pipes 26, 2 for each cleaning hood 24, 24' at each stage via ducts 23, 23'
6' and are introduced separately into the cyclones 34 and 35 of the cyclone dust collector 29 in the suction gas cleaning device. On the other hand, the gas containing dust from the coarse particle duct 9 is also introduced into the cyclone 36 of the cyclone dust collector 29 through the suction gas pipe 26''.
4, 35, and 36, and the gas after separating the dust is sucked by a blower 31 and sent to a bag filter 30 through a gas pipe 37, where further dust removal is performed to make it clean. It is considered a gas. At this time, in the present invention, the cleaning hood 2
4 and 24' are small and the amount of gas sucked in by the hoods 24 and 24' is small, about a few tenths of the amount of the main flow of gas flowing in the dry dust collector, so the downstream bag filter 30 etc., and the system including the same (suction gas cleaning device) can be downsized, and pressure and heat loss are also very small, making it possible to increase the amount of energy recovered.

The gas purified by the bag filter 30 is sent to the energy recovery section by the blower 31.

Next, the gas purified by the dry dust collector and the suction gas purifier is guided to the gas turbine 39 in the energy recovery section in order to effectively utilize the stored energy, and the gas is passed through the gas turbine 39 to rotate the turbine 39 and generate a generator 4.
1 to perform the work of activating it. The clean gas that has finished its work is stored in the gas holder 3.

In addition, each cyclone 3 of the cyclone dust collector 29
The fine dust separated from the gas in steps 4, 35, and 36 settles in the hopper bin 33 and passes through the cut-out portion 3 at the lower end.
It is cut out from 8.

The blast furnace exhaust gas treatment equipment of the present invention has been explained above, but in the case of blast furnace exhaust gas, due to the peculiarities of blast furnace operation, gas suction inside the furnace and slipping of raw materials occur, and the gas temperature rises abnormally in a very short period of time. The blast furnace exhaust gas temperature, which is normally around 150 to 200℃, can reach 800℃.
Or even more. Gas with such an abnormally high temperature causes a decrease in dust collection performance and damage to equipment. Therefore, if a heat storage device 27 is provided downstream of the coarse precipitator 8 of the dry type precipitator and upstream of the packed bed 10 as shown in Fig. 2, an abnormality such as the above-mentioned temperature of 800°C, which rarely occurs in a short period of time, can be avoided. The increased temperature can be absorbed by the heat storage device 27, and the above-mentioned abnormally increased temperature can be reduced to less than about 300°C. Providing the heat storage device 27 in this manner not only makes it possible to equalize the temperature of the exhaust gas, prevent deterioration of the dust collection performance of the dust collector and damage to equipment, but also makes it possible to equalize the output of the gas turbine.

As described above, according to the blast furnace exhaust gas treatment equipment of the present invention, (i) the dry dust collector can collect dust continuously and with high collection efficiency, so that the temperature drop and pressure drop can be reduced from the high temperature and high pressure blast furnace exhaust gas; The energy of the clean gas can be effectively recovered, leading to energy savings.

(ii) A dry type dust collector has a coarse dust collector and a fine dust collector in one container, and the coarse dust collector creates a reversed transverse flow to coarsely collect dust by gravity settling of the dust, so it has a simple and effective mechanism. Dust collection is possible.

(iii) To remove fine dust in a dry type dust collector, the dust collected and deposited in the packed bed is suspended and removed by suction using a cleaning hood upstream of the packed bed, so there is no need for a space for dust settling as in the past. is not necessary and can be carried out continuously, and since there is no movement of the filter material itself, the collection efficiency is very high.

(iv) Since the amount of gas sucked in by the cleaning hood is small, the system for cleaning this gas can be made smaller and simpler, and the overall equipment can be made cheaper.

(v) Since the gas purified by the suction gas purifier is returned to the main gas stream, the gas can be used effectively, and if the exhaust gas pressure is about 0.8 atm or more, the total pressure loss of the suction gas purifier is The pressure is much lower than that of exhaust gas, so even if the pressure is increased by a blower (even if the blower consumes electricity), more energy can be recovered by the gas turbine.

It can produce excellent effects such as

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing the entire blast furnace exhaust gas treatment equipment of the present invention, Fig. 2 is an explanatory partial view of a dry dust collector in the equipment of the present invention, and Fig. 3 is an enlarged view taken in the direction of arrow A in Fig. 2. , FIG. 4 is an enlarged view of arrow B in FIG. 2, FIG. 5 is an explanatory diagram of the cyclone dust collector of the suction gas purification device in the equipment of the present invention, and FIG. 6 is an illustration of the suction gas purification device and the energy recovery section. It is a schematic diagram. …dry dust collector, …suction gas purifier, …
Energy recovery section, 1... Blast furnace, 3... Gas holder, 5... Container, 8... Rough dust collector, 10, 10'... Packed bed, 12... Wear-resistant filter material, 14... Rotating cylinder, 2
4, 24'...Cleaning hood, 29...Cyclone dust collector, 30...Bag filter, 31...Blower, 3
3... hopper bin, 34, 35, 36... cyclone, 39... gas turbine.

Claims (1)

[Claims] 1. A container with a gas inlet at the top and a clean gas outlet at the bottom so that gas flows from above to below, a vertical coarse duct installed in the center of the container, and the coarse duct. a coarse dust collector connected above and having an inverted conical hopper with a large diameter at the upper end for receiving coarse particles removed by its own weight from the gas traversing the upper part of the container; A rotatable cylinder arranged concentrically, and a horizontal annular filling filled with a filter material such as sand, which is arranged below the coarse dust collector hopper in the container and on the outer circumference of the cylinder. a cleaning hood disposed above the packed bed that suspends and suctions dust collected in the packed bed by gas flowing back through the packed bed from below, and one end connected to the cleaning hood and the other end a dry dust collector comprising a particulate duct whose side is fixed to the rotating cylinder, and a suction gas pipe disposed at the bottom of the rotating cylinder and sucking gas and dust introduced from the cleaning hood through the particulate duct; a cyclone dust collector that separates dust from the gas sucked from the suction gas pipe; a bag filter that further removes dust from the gas removed by the cyclone dust collector; and suction of the clean gas removed by the bag filter. a suction gas cleaning device equipped with a blower for cleaning, a turbine driven by the introduction of clean gas from the clean gas outlet of the dry precipitator and the suction gas cleaning device, and a generator rotated by the turbine. A blast furnace exhaust gas treatment facility characterized by being equipped with an energy recovery section.