JP2012219358A - Dry type dust collection system and dry type gas collection method for furnace gas in blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dry type dust collection system for furnace gas in a blast furnace, stably performing temperature rising of furnace gas in a starting operation from the stopping of blasting in a blast furnace, with an inexpensive constitution and capable of increasing a power recovery amount by a TRT.SOLUTION: A furnace gas temperature adjustment means 6 adjusting the temperature of furnace gas G includes: a furnace gas heat exchanger 61 provided in furnace gas piping 721; a furnace gas temperature measuring means 62 measuring the temperature of the furnace gas G before heat exchange in the furnace gas heat exchanger 61; and a heating medium switching means 67 switching a heating state, where a heated heating medium flowing out from an exhaust gas heat exchanger 51 is flowed in the furnace gas heat exchanger 61 and the furnace gas G is heated by heat exchange with the heated heating medium flowed in, and a cooling state, where the cooled heating medium flowing out from a fuel gas heat exchanger 52 and a combustion air heat exchanger 53 is flowed in the furnace gas heat exchanger 61 and the furnace gas G is cooled by heat exchange with the cooled heating medium flowed in.

Description

  The present invention relates to a dry dust collection system for a blast furnace top gas and a dry dust collection method.

The blast furnace is equipped with a top pressure recovery turbine (TRT) for recovering the temperature and pressure energy of the blast furnace top gas as electric power, and a dust collection facility for removing dust in the blast furnace top gas. . There are two types of dust collection equipment: dry dust collectors and wet dust collectors.
By the way, when using a dry dust collector as dust collection equipment, the following problems may occur.

When the blast furnace rest wind rises or the blast furnace cools down, if the furnace top gas temperature is low and falls below the temperature (about 60 ° C) in the dry dust collector installed afterwards, the condensation will occur on the filter cloth of the dry dust collector. Dust adheres and the gas flow path is blocked. For this reason, the dust collection capacity of the dry dust collector is reduced.
In addition, when the blast furnace is blown through, if the furnace top gas temperature is higher than the temperature at which the filter cloth is burned (about 200 ° C.), the filter cloth is burned out and the dry dust collector itself does not function.

In both cases, in the worst case, it is assumed that the blast furnace will be closed.
In addition, when the blast furnace is cooled or blown through, it is difficult to restore the normal operation state, and in some cases, an emergency may continue on the order of days or months.
Then, examination for solving the problem in such a dry type dust collector is made (for example, refer to patent documents 1 and 2).

  In Patent Document 1, a dedicated gas combustion furnace for raising the temperature of the furnace top gas is installed, and when the temperature of the furnace top gas becomes low, the gas heated in this gas combustion furnace is supplied to the upstream side of the dry dust collector. The furnace top gas is heated up by being led to a heat exchanger installed in the factory. The furnace top gas after this temperature rise is led to a dry dust collector to prevent condensation in the dry dust collector. When the furnace top gas temperature is high, the furnace top gas temperature is lowered by injecting cooling water into the furnace top gas with a liquid injector on the upstream side of the dry dust collector.

  In patent document 2, while installing a heat-medium type heat exchanger before and behind a dry-type dust collector, the thermal storage body is installed in the middle of the heat-medium piping. The temperature of the furnace top gas is appropriately controlled by heating or cooling the furnace top gas using the heat stored in the heat storage body. Further, by using such a configuration, conventionally, the wet dust collector provided for emergency when the furnace top gas temperature is abnormally high or low is abolished, and dust is collected only by the dry dust collector.

Japanese Utility Model Publication No. 3-18500 JP 2007-46113 A

  However, in the configuration as in Patent Document 1, it is necessary to newly construct a gas pipe for a gas combustion furnace. Furthermore, since the temperature of the heat exchanger is raised by gas, it is necessary to construct a thick pipe up to the heat exchanger. For this reason, it is not economically reasonable.

On the other hand, in the configuration as in Patent Document 2, the required capacity of the heat storage body changes depending on the operation status, and further, there is also heat dissipated from the heat storage body, so it is difficult to determine the capacity of the heat storage body.
In addition, the amount of heat supplied for raising the temperature of the furnace top gas and the amount of heat removed for cooling change depending on the operating state. In such a changing situation, the heat storage body may radiate heat continuously, and depending on the operation situation, there is a possibility that the necessary amount of heat cannot be secured.
Therefore, there is a possibility that the capacity of the heat storage body is insufficient, and it is still necessary to install a wet dust collector, and further, the amount of power recovered by TRT is reduced due to the use of the wet dust collector.

  An object of the present invention is to provide a dry dust collection system for blast furnace top gas that can stably implement measures for abnormally high and low temperatures of blast furnace top gas with an inexpensive configuration and increase the amount of power recovered by TRT, and It is to provide a dry dust collection method.

  The dry dust collection system of the present invention includes a blast furnace, a hot blast furnace for supplying hot blast to the blast furnace, fuel gas supply means and combustion air supply means for supplying fuel gas and combustion air to the hot blast furnace, and the hot blast furnace. An exhaust heat reuse system for reusing the exhaust gas of the above, a furnace top gas temperature adjusting means for adjusting the temperature of the furnace top gas generated from the blast furnace, a dry dust collector for removing dust in the furnace top gas, and A furnace top pressure recovery turbine driven by furnace top gas from a dry dust collector, and the exhaust heat reuse system is provided in an exhaust gas pipe from the hot stove, between the inflowing heat medium and the exhaust gas Exhaust gas heat exchanger for exchanging heat and allowing the heated heat medium to flow out, fuel gas piping connecting the fuel gas supply means and the hot stove, and connecting the combustion air supply means and the hot stove Provided in each combustion air pipe and heat-exchanged with the heat medium heated by the exhaust gas heat exchanger to heat the fuel gas and combustion air, and the cooled heat medium to the exhaust gas heat exchanger In the dry dust collection system for blast furnace top gas composed of a fuel gas heat exchanger and a combustion air heat exchanger to be introduced, the top gas temperature adjusting means connects the blast furnace and the dry dust collector A furnace top gas heat exchanger that is provided in the furnace top gas pipe and performs heat exchange between the inflowing heat medium and the furnace top gas and flows out the heat medium, and heat in the furnace top gas heat exchanger Furnace top gas temperature measuring means for measuring the temperature of the furnace top gas before replacement, and heat medium switching means for switching the heat medium inflow source and the heat medium outflow destination in the furnace top gas heat exchanger, The heat medium switching means measures the furnace top gas temperature. On the basis of the measurement results of the means, the heated heat medium flowing out from the exhaust gas heat exchanger is caused to flow into the furnace top gas heat exchanger, and the furnace is exchanged with the heated heat medium that has been introduced. A heating state in which the top gas is heated and the deprived heat medium flows out to the exhaust gas heat exchanger, and the deprived heat medium flowing out from the fuel gas heat exchanger and the combustion air heat exchanger is removed from the furnace. The gas is introduced into the top gas heat exchanger, and the furnace top gas is cooled by heat exchange with the heat medium after deprived heat that has flowed in, and the heated heat medium is exchanged with the fuel gas heat exchanger and the combustion air heat exchange. It is configured to be switchable between a cooling state to be discharged to the vessel.

  The dry dust collection method of the present invention includes a blast furnace, a hot blast furnace for supplying hot air to the blast furnace, fuel gas supply means for supplying fuel gas and combustion air to the hot blast furnace, combustion air supply means, and the hot air An exhaust heat recycling system that reuses exhaust gas from the furnace, a dry dust collector that removes dust in the furnace top gas, and a furnace top pressure recovery turbine that is driven by the furnace top gas from the dry dust collector. The exhaust heat reuse system is provided in an exhaust gas pipe from the hot stove, and an exhaust gas heat exchanger for exchanging heat between the inflowing heat medium and the exhaust gas and causing the heated heat medium to flow out. , A fuel gas pipe connecting the fuel gas supply means and the hot stove, and a combustion air pipe connecting the combustion air supply means and the hot stove, respectively, and heated by the exhaust gas heat exchanger A fuel gas heat exchanger and a combustion air heat exchanger that heat the fuel gas and the combustion air with each other and heat the cooled heat medium into the exhaust gas heat exchanger. A dry dust collection method using a dry dust collection system for a blast furnace top gas, wherein the dry dust collection system is provided in a furnace top gas pipe connecting the blast furnace and the dry dust collector; A furnace top gas heat exchanger that exchanges heat with the furnace top gas and flows out the heat medium, and a furnace top gas that measures the temperature of the furnace top gas before heat exchange in the furnace top gas heat exchanger. Gas temperature measuring means and heat medium switching means for switching the heat medium inflow source and the heat medium outflow destination in the furnace top gas heat exchanger are provided, and the temperature measured by the furnace gas temperature measuring means is previously measured. If it is determined that it is less than the set lower limit, The heated heating medium flowing out from the exhaust gas heat exchanger was caused to flow into the furnace top gas heat exchanger, and the furnace top gas was heated by heat exchange with the heated heating medium that was introduced, and was deprived of heat. When the heating medium is set to a heating state that flows out to the exhaust gas heat exchanger and is determined to be equal to or higher than a preset upper limit value, after the heat removal flowing out from the fuel gas heat exchanger and the combustion air heat exchanger A heat medium is caused to flow into the furnace top gas heat exchanger, the furnace top gas is cooled by heat exchange with the heat medium that has been deprived, and the heated heat medium is converted into the fuel gas heat exchanger and The cooling state is set to flow out to the combustion air heat exchanger.

According to the present invention as described above, the temperature of the top gas is adjusted using the exhaust gas, the fuel gas, and the combustion air of the hot air furnace that supplies the hot air to the blast furnace. Specifically, when it is desired to increase the temperature of the furnace top gas, the temperature of the furnace top gas is increased using a heat medium heated by heat exchange between the fuel gas and the combustion air. On the other hand, when it is desired to lower the temperature of the furnace top gas, the temperature of the furnace top gas is lowered using an unheated heat medium used for heat exchange with the exhaust gas.
For this reason, since the exhaust gas from the hot stove that is always in operation is used during the operation of the blast furnace, the temperature of the furnace top gas can be adjusted at any time, and the temperature rise and cooling of the furnace top gas can be performed stably. It can be performed. Therefore, a wet dust collector is not required, and only a dry dust collector can be used, so that it is possible to prevent a reduction in power recovery amount due to TRT. In addition, because the temperature of the furnace top gas is adjusted using the exhaust heat reuse system, a furnace top gas heat exchanger is provided in the furnace top gas piping, and the heat medium circulated in the exhaust heat reuse system It is only necessary to provide a path for supplying the gas to the furnace top gas heat exchanger. Furthermore, a relatively small size pipe can be used for circulating the heat medium. Therefore, an increase in equipment cost can be suppressed.

  In the dry dust collection system of the present invention, the heat medium switching means adjusts the flow rate of the heated heat medium flowing out from the exhaust gas heat exchanger and flowing into the furnace top gas heat exchanger. A second heat medium inlet valve that adjusts the flow rate of the heat medium after heat removal flowing out of the fuel gas heat exchanger and the combustion air heat exchanger and flowing into the furnace top gas heat exchanger, and the furnace top A first heat medium outlet valve for adjusting the flow rate of the heat medium after heat removal flowing out from the gas heat exchanger and flowing into the exhaust gas heat exchanger; and the fuel gas heat exchanger flowing out from the furnace top gas heat exchanger And a second heat medium outlet valve that adjusts the flow rate of the heated heat medium flowing into the combustion air heat exchanger, and the furnace top gas temperature adjusting means is configured to heat the heat in the furnace top gas heat exchanger. A furnace top gas flow rate measuring means for measuring a flow rate of the furnace top gas before replacement; First heat medium measuring means for measuring the temperature and flow rate of the heated heat medium flowing into the medium inflow valve, and second temperature for measuring the temperature and flow rate of the cooled heat medium flowing into the second heat medium inflow valve It is preferable to include a heat medium measuring unit.

Here, for example, when the time for raising the temperature of the furnace top gas to the target temperature is made constant regardless of the temperature of the furnace top gas, the higher the flow rate of the furnace top gas, the more per unit time given to the furnace top gas. It is necessary to increase the amount of heat.
According to this invention, the flow rate of the heat medium used for heat exchange with the furnace top gas by adjusting the first heat medium inlet valve according to the temperature of the heat medium flowing into the furnace top gas heat exchanger. Can be adjusted. That is, the amount of heat per unit time given to the furnace top gas can be adjusted. Therefore, the necessary amount of heat according to the flow rate of the furnace top gas to be temperature-adjusted can be given to the furnace top gas, and the time for raising the temperature of the furnace top gas to the target temperature regardless of the temperature of the furnace top gas. Can be constant.

  In the dry dust collection system of the present invention, when the furnace top gas temperature adjusting means determines that the temperature measured by the furnace top gas temperature measuring means is less than a preset lower limit value, the heat medium switching means is When the heating state is set and it is determined that it is equal to or higher than a preset upper limit value, the heating medium switching means sets the heating medium switching means to the cooling state, and the heating medium control means includes the furnace top gas Based on the measurement results of the flow rate measuring means, the first heat medium measuring means, and the second heat medium measuring means, the first heat medium inflow valve, the second heat medium inflow valve, and the first heat medium. It is preferable to adjust the flow rate of the heat medium flowing into the furnace top gas heat exchanger by controlling the outflow valve and the second heat medium outflow valve.

  According to the present invention, since the temperature of the furnace top gas can be appropriately adjusted by automatic control by the heat medium control means, the response can be instantly performed and the load on the operator can be reduced.

  In the dry dust collection system of the present invention, the furnace top gas pipe is more than a heat exchanger installation pipe in which the furnace top gas heat exchanger is installed, and the furnace top gas heat exchanger in the heat exchanger installation pipe. A bypass pipe that connects the blast furnace side and the dry dust collector side with respect to the furnace top gas heat exchanger, and the furnace top gas temperature adjusting means distributes the furnace top gas to the heat exchanger installation pipe. Heat exchange state switching means for switching between a heat exchange state in which heat exchange of the furnace top gas is performed and a non-heat exchange state in which the furnace top gas is circulated through the bypass pipe and heat exchange of the furnace top gas is not performed. It is preferable to provide.

  According to the present invention, the furnace top gas heat exchanger is switched only when necessary by switching between the heat exchange state in which the heat exchange of the exhaust gas is performed and the non-heat exchange state in which the heat exchange is not performed by the heat exchange state switching means. Can be used, and the life of the furnace top gas heat exchanger can be extended.

  In the dry dust collection system of the present invention, the furnace top gas temperature adjusting means is such that the temperature measured by the furnace top gas temperature measuring means is less than a preset lower limit value or more than a preset upper limit value. The heat exchange state switching means is set to the heat exchange state, and if it is determined that the heat exchange state switching means is less than the upper limit value and less than the upper limit value, the heat exchange state switching means is set to the non-heat exchange state. It is preferable to provide an exchange control means.

  According to the present invention, it is possible to appropriately adjust whether or not the heat exchange of the furnace top gas is performed by automatic control by the heat exchange control means. Therefore, it is possible to instantly cope with the situation and reduce the load on the operator.

The schematic diagram which shows the dry dust collection system of the blast furnace top gas which concerns on one Embodiment of this invention. The block diagram which shows the principal part of the furnace top gas temperature adjustment means of the said dry-type dust collection system. Explanatory drawing which shows the effect | action at the time of starting in the said dry-type dust collection system. Explanatory drawing which shows an effect | action when raising the furnace top gas temperature in the said dry-type dust collection system. Explanatory drawing which shows an effect | action when lowering the furnace top gas temperature in the said dry-type dust collection system.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Configuration of dry dust collection system]
In FIG. 1, a dry dust collection system 1 includes a blast furnace 2, two hot blast furnaces 3 for supplying hot air to the blast furnace 2, fuel supply means 4 for supplying fuel to the hot blast furnace 3, and a heat medium. The exhaust heat reuse system 5 for reusing the heat of the exhaust gas E generated from the chimney 31, the furnace top gas temperature adjusting means 6 for adjusting the temperature of the furnace top gas G generated from the blast furnace 2, and the hot stove 3, a dust collection facility 7 that removes solid particles in the furnace top gas G whose temperature has been adjusted in 3, and a TRT 8 that is driven by the furnace top gas G from which solid particles have been removed by the dust collection equipment 7.

The hot stove 3 includes a combustion chamber (not shown) and a heat storage chamber.
The combustion chamber mixes and burns fuel gas and combustion air supplied from the fuel supply means 4.
In the heat storage chamber, heat generated from the combustion gas in the combustion chamber is stored, and the exhaust gas E after the heat storage is discharged from the chimney 31. On the other hand, in the heat storage chamber, after the heat storage is completed, the stored heat is transmitted to the air introduced from the blower 32 to generate hot air W, which is supplied to the tuyere of the blast furnace 2. In addition, the number of the hot stove 3 may be three or more.

The fuel supply means 4 includes a fuel gas supply means 41 for supplying fuel gas to the hot stove 3 and a combustion air supply means 42 for supplying combustion air to the hot stove 3 at a predetermined ratio to the fuel gas. Prepare.
Further, a fuel gas pipe 411 extending from the fuel gas supply means 41, a combustion air pipe 421 extending from the combustion air supply means 42, an exhaust gas pipe 311 extending to the chimney 31, a pipe 321 extending from the blower 32, and a blade (not shown) of the blast furnace 2 Each of the pipes 201 extending to the mouth is branched into two and connected to the two hot stoves 3. Further, a valve 43, a valve 44, a valve 33, a valve 34, and a valve 21 are provided on the hot stove 3 side of the branch point in the fuel gas pipe 411, the combustion air pipe 421, the exhaust gas pipe 311, the pipe 321, and the pipe 201, respectively. It has been.

  The exhaust heat reuse system 5 includes an exhaust gas heat exchanger 51, a fuel gas heat exchanger 52, a combustion air heat exchanger 53, a heat medium storage tank 54, and an expansion tank 55. In the following, a low-temperature heat medium that is not heated may be referred to as a low-temperature medium L, and a heated high-temperature heat medium may be referred to as a high-temperature medium H.

The exhaust gas heat exchanger 51, the fuel gas heat exchanger 52, and the combustion air heat exchanger 53 are arranged on the chimney 31 side of the exhaust gas pipe 311, the fuel gas pipe 411, and the combustion air pipe 421, the fuel gas. Provided on the supply means 41 side and the combustion air supply means 42 side, respectively.
The high temperature pipe 511 extending from the outlet of the exhaust gas heat exchanger 51 is branched into two, and is connected to the inlets of the fuel gas heat exchanger 52 and the combustion air heat exchanger 53, respectively. A cryogenic pipe 512 extending from the inlet of the exhaust gas heat exchanger 51 is also branched into two and connected to the outlets of the fuel gas heat exchanger 52 and the combustion air heat exchanger 53, respectively. The cryogenic pipe 512 is provided with a circulation pump 56 for circulating the heat medium.

The heat medium storage tank 54 is connected to the cryogenic pipe 512 via a pipe 541. The pipe 541 is provided with a supply pump 57 that supplies the heat medium stored in the heat medium storage tank 54 to the cryogenic pipe 512.
The expansion tank 55 is connected to the low-temperature pipe 512 via the pipe 551, and absorbs the heat medium corresponding to the expansion when the heat medium in the low-temperature pipe 512 expands.

The dust collector 7 includes a dust remover 71 and a dry dust collector 72.
The dry dust collector 72 is connected to the dust remover 71 via the furnace top gas pipe 721 and connected to the TRT 8 via the pipe 724. The dry dust collector 72 includes a filter cloth (not shown). Then, the dry dust collector 72 removes the dust of the furnace top gas G with a filter cloth and supplies it to the TRT 8. The furnace top gas pipe 721 connects the dust remover 71 and the dry dust collector 72 and has a heat exchanger installation pipe 722 in which a furnace top gas heat exchanger 61 described later is installed, and a furnace top in the heat exchanger installation pipe 722. A bypass pipe 723 that connects the dust remover 71 side and the dry dust collector 72 side to the gas heat exchanger 61 is provided.

Here, if the temperature of the furnace top gas G is too high, the filter cloth of the dry dust collector 72 is burned out. If the temperature is too low, the filter cloth is condensed and the dust collection performance of the dry dust collector 72 is lowered. Therefore, it is necessary to appropriately control the temperature of the furnace top gas G.
The furnace top gas temperature adjusting means 6 is for eliminating such problems, and the furnace top gas heat exchanger 61, the furnace top gas temperature measuring means 62, the furnace top gas flow rate measuring means 63, the first 1 heat medium measuring means 64, second heat medium measuring means 65, heat exchange state switching means 66, heat medium switching means 67, gas temperature measuring means 68 after heat exchange, and control device 69 (see FIG. 2) With.

  The furnace top gas heat exchanger 61 is installed in the heat exchanger installation pipe 722 and performs heat exchange between the heat medium circulated in the exhaust heat reuse system 5 and the furnace top gas G. An inlet pipe 611 is connected to the inlet of the furnace top gas heat exchanger 61, and an outlet pipe 612 is connected to the outlet. The inlet pipe 611 is branched into two, and the leading ends of the branches are connected to the high temperature pipe 511 and the low temperature pipe 512, respectively. Further, the outlet pipe 612 is also branched into two, and the tips of the branches are connected to the high temperature pipe 511 and the low temperature pipe 512, respectively. In addition, the connection point with the inlet pipe 611 in the high temperature pipe 511 is located upstream from the connection point with the outlet pipe 612. Further, the connection point of the cryogenic pipe 512 with the inlet pipe 611 is located downstream of the connection point with the outlet pipe 612.

  The furnace top gas temperature measuring means 62 and the furnace top gas flow rate measuring means 63 are installed in the pipe 711. The furnace top gas temperature measuring means 62 measures the temperature of the furnace top gas G before heat exchange in the furnace top gas heat exchanger 61, and the furnace top gas flow rate measuring means 63 is measured by the furnace top gas heat exchanger 61. The flow rate of the top gas G before heat exchange is measured. Then, the furnace top gas temperature measuring means 62 and the furnace top gas flow rate measuring means 63 output the measurement results to the control device 69.

  The first heat medium measuring means 64 is upstream of the connection point with the inlet pipe 611 in the high temperature pipe 511, and the second heat medium measurement means 65 is upstream of the connection point with the inlet pipe 611 in the low temperature pipe 512. Are provided respectively. The first heat medium measuring means 64 includes a heat medium temperature measuring means 641 that measures the temperature of the heat medium flowing through the high temperature pipe 511 and a heat medium flow measuring means 642 that measures the flow rate of the heat medium. Similarly, the second heat medium measuring means 65 includes a heat medium temperature measuring means 651 that measures the temperature and flow rate of the heat medium flowing through the cryogenic pipe 512, and a heat medium flow rate measuring means 652, respectively. The first heat medium measuring means 64 and the second heat medium measuring means 65 are the measurement results of the heat medium temperature measuring means 641, the heat medium temperature measuring means 651, the heat medium flow measuring means 642, and the heat medium flow measuring means 652. Is output to the control device 69.

  The heat exchange state switching means 66 switches between a heat exchange state in which the furnace top gas G performs heat exchange in the furnace top gas heat exchanger 61 and a non-heat exchange state in which heat exchange is not performed. The heat exchange state switching means 66 includes a pair of heat switching valves 661 provided on the dust remover 71 side and the dry dust collector 72 side of the furnace top gas heat exchanger 61 in the heat exchanger installation pipe 722, and a bypass pipe 723. And a bypass valve 662 provided in The heat switching valve 661 and the bypass valve 662 are configured such that the opening degree can be continuously adjusted under the control of the control device 69.

The heat medium switching means 67 switches the heat medium flowing into the furnace top gas heat exchanger 61 and adjusts the flow rate of the heat medium. The heat medium switching means 67 includes a first heat medium inflow valve 671, a second heat medium inflow valve 672, a first heat medium outflow valve 673, and a second heat medium outflow valve 674.
The first heat medium inflow valve 671 is installed closer to the high temperature pipe 511 than the branch point in the inlet pipe 611, and the second heat medium inflow valve 672 is installed closer to the cold pipe 512 than the branch point. Further, the first heat medium outflow valve 673 is installed closer to the low temperature pipe 512 than the branch point in the outlet pipe 612, and the second heat medium outflow valve 674 is installed closer to the high temperature pipe 511 than the branch point. . The first heat medium inflow valve 671, the second heat medium inflow valve 672, the first heat medium outflow valve 673, and the second heat medium outflow valve 674 are configured such that the opening degree can be continuously adjusted under the control of the control device 69. Has been.
The post-heat exchange gas temperature measuring means 68 is provided on the downstream side of the furnace top gas heat exchanger 61 in the furnace top gas pipe 721, measures the temperature of the furnace top gas after heat exchange with the heat medium, and measures the temperature. The result is output to the control device 69.

The control device 69 is a so-called computer, and a hot stove control means 691 configured by a CPU (Central Processing Unit) processing a program and data stored in a storage means (not shown), a heat exchange control means 692, A heat medium control means 693.
The hot stove control means 691 operates the two hot stoves 3 as necessary to supply hot air W to the blast furnace 2 or exhaust the exhaust gas E for use in adjusting the temperature of the top gas G. To do.
The heat exchange control unit 692 controls the heat exchange state switching unit 66 to switch between a heat exchange state in which the furnace top gas G is heated or cooled and a non-heat exchange state in which neither heating nor cooling is performed.
The heat medium control unit 693 controls the heat medium switching unit 67 to switch between a heating state in which the furnace top gas G is heated and a cooling state in which the furnace top gas G is cooled.

[Operation of dry dust collection system]
Next, the operation of the dry dust collection system 1 will be described. In the following description, a high-temperature heat medium may be referred to as a high-temperature medium H, and a low-temperature heat medium may be referred to as a low-temperature medium L.

First, when the dry dust collection system 1 is started up, the hot stove control means 691 of the control device 69 closes all the valves 21 and 34 and closes all the valves 43 and 44 as shown in FIG. Open the valve 33. Then, the fuel gas is supplied from the fuel gas supply means 41 to the hot stove 3 in the lower part of FIG. 1, and the combustion air is supplied from the combustion air supply means 42 to the hot stove 3 so that the combustion in the combustion chamber of the hot stove 3 is performed. Start.
On the other hand, the heat exchange control means 692 of the control device 69 closes the first heat medium inflow valve 671, the second heat medium inflow valve 672, the first heat medium outflow valve 673, and the second heat medium outflow valve 674, and the circulation pump 56 is rotated to supply a heat medium to the low temperature pipe 512, and this heat medium is supplied between the exhaust gas heat exchanger 51 and the fuel gas heat exchanger 52 via the low temperature pipe 512 and the high temperature pipe 511, and the exhaust gas heat. Circulation is performed between the exchanger 51 and the combustion air heat exchanger 53.
Further, the heat medium control means 693 of the control device 69 closes the heat switching valve 661 and opens the bypass valve 662 to set the non-heat exchange state in which the top gas G can flow through the bypass pipe 723.

When the hot stove control means 691 detects that the temperature in the combustion chamber of the hot stove 3 has risen sufficiently, as shown in FIG. 3, the valves 34 and 21 corresponding to the hot stove 3 in FIG. Is opened, the valve 33 corresponding to the hot stove 3 is closed, the air from the blower 32 is introduced into the combustion chamber, and the hot air W heated in the combustion chamber is supplied to the tuyere of the blast furnace 2.
On the other hand, the exhaust gas E generated in the hot stove 3 in the lower part of FIG. 3 during the temperature rise is introduced into the exhaust gas heat exchanger 51 through the exhaust gas pipe 311. The exhaust gas E is exhausted from the chimney 31 after heat is removed from the exhaust gas heat exchanger 51 by heat exchange with the low-temperature medium L supplied from the low-temperature pipe 512.

The low temperature medium L flowing into the exhaust gas heat exchanger 51 from the low temperature pipe 512 is heated by heat exchange with the exhaust gas E, and flows out to the high temperature pipe 511 as the high temperature medium H. The high temperature medium H flows into the fuel gas heat exchanger 52 and the combustion air heat exchanger 53, and after heat is taken away by heat exchange between the fuel gas and the combustion air, flows out into the low temperature pipe 512 as the low temperature medium L. To do. This low-temperature medium L flows into the exhaust gas heat exchanger 51 again and is used for heat exchange with the exhaust gas E as described above.
On the other hand, the fuel gas and the combustion air are heated by heat exchange with the high-temperature medium H in the fuel gas heat exchanger 52 and the combustion air heat exchanger 53. By introducing the heated fuel gas and combustion air into the hot stove 3, combustion in the combustion chamber is promoted.

  In the blast furnace 2, pig iron is manufactured using hot air W introduced into the tuyere. The top gas G generated during the production is introduced into the dust remover 71 and the dry dust collector 72 through the pipe 711 and the bypass pipe 723, and the dust is removed. The furnace top gas G from which the dust has been removed is introduced into the TRT 8 and used for driving the TRT 8.

The heat exchange control means 692 of the control device 69 has a preset lower limit value (for example, 70 ° C.) based on the measurement result of the furnace top gas temperature measuring means 62, the temperature of the furnace top gas G discharged from the blast furnace 2. ) To increase the temperature of the furnace top gas G, the heat switching valve 661 is opened, the bypass valve 662 is closed, and the furnace top gas G is transferred to the heat exchanger installation pipe 722 as shown in FIG. Is set to a heat exchange state that allows circulation.
Further, the heat medium control means 693 of the control device 69 switches the heat medium switching means 67 to a heating state in order to increase the temperature of the furnace top gas G. Specifically, the first heat medium inflow valve 671 and the first heat medium outflow valve 673 are opened. By this switching, the high temperature medium H flowing through the high temperature pipe 511 also flows into the inlet pipe 611. The furnace top gas G flowing through the heat exchanger installation pipe 722 is heated by heat exchange with the high-temperature medium H in the furnace top gas heat exchanger 61. Since the furnace top gas G adjusted to an appropriate temperature by this heating flows into the dry dust collector 72, the problem that the filter cloth of the dry dust collector 72 is condensed is suppressed.

  Here, the heat medium control means 693 opens the first heat medium inlet valve 671 based on the measurement results of the furnace top gas temperature measuring means 62, the furnace top gas flow rate measuring means 63, and the first heat medium measuring means 64. By adjusting the degree, the time required for raising the furnace top gas G to the target temperature is made substantially the same regardless of the temperature of the furnace top gas G.

When the temperature of the top gas G discharged from the blast furnace 2 is determined to be equal to or higher than a preset upper limit value (for example, 180 ° C.), the heat exchange control unit 692 As shown in FIG. 5, the heat exchange state switching means 66 is set to the heat exchange state.
Further, the heat medium control means 693 switches the heat medium switching means 67 to the cooling state in order to lower the temperature of the furnace top gas G. Specifically, by opening the second heat medium inflow valve 672 and the second heat medium outflow valve 674, the low temperature medium L flowing through the low temperature pipe 512 is caused to flow into the inlet pipe 611. The furnace top gas G flowing through the heat exchanger installation pipe 722 is cooled to an appropriate temperature by heat exchange with the low temperature medium L in the furnace top gas heat exchanger 61 and flows into the dry dust collector 72. Thereby, the malfunction that the filter cloth of the dry dust collector 72 will burn out is suppressed.

Here, the heat medium control means 693 opens the second heat medium inflow valve 672 based on the measurement results of the furnace top gas temperature measuring means 62, the furnace top gas flow rate measuring means 63, and the second heat medium measuring means 65. By adjusting the degree, the time required for lowering the furnace top gas G to the target temperature is made substantially the same regardless of the temperature of the furnace top gas G.
The hot stove control means 691 adjusts the flow rates of the fuel gas and the combustion air based on the temperature at the downstream side of the furnace top gas heat exchanger 61 measured by the gas temperature measuring means 68 after heat exchange. Thus, necessary calorie calories are secured in the hot stove 3.

[Effect of dry dust collection system]
Thus, in this embodiment, the exhaust gas E from the hot blast furnace 3 that supplies hot blast to the blast furnace 2 is used to adjust the temperature of the furnace top gas G so that the dust collection capacity of the dry dust collector 72 does not decrease. ing.
For this reason, since the exhaust gas E of the hot stove 3 that is always in operation is used during the operation of the blast furnace 2, when the temperature adjustment of the furnace top gas G is necessary, the rise of the furnace top gas G is stably performed. Temperature and cooling can be performed. Accordingly, the wet dust collector is not required, and only the dry dust collector 72 can be used, so that it is possible to prevent the power recovery amount from being reduced by the TRT 8. In particular, when the dry dust collection system 1 is newly installed, the installation cost of the wet dust collector can be reduced and can be newly installed at low cost. In addition, since the temperature of the furnace top gas G is adjusted using the exhaust heat reuse system 5, a furnace top gas heat exchanger 61 is provided in the furnace top gas pipe 721 and is circulated in the exhaust heat reuse system 5. It is only necessary to provide a path for supplying the heated heat medium to the furnace top gas heat exchanger 61. Furthermore, since the temperature of the furnace top gas G is adjusted by circulation of the heat medium, a relatively small size can be used as the inlet pipe 611 and the outlet pipe 612 for circulating the heat medium. Therefore, an increase in equipment cost can be suppressed.

A furnace top gas flow measuring means 63 for measuring the flow rate of the furnace top gas G, and a first heat medium measuring means 64 and a second heat medium for measuring the temperature and flow rate of the hot medium H and the cold medium L flowing into the inlet pipe 611. A measuring means 65 and a first heat medium inflow valve 671 and a second heat medium inflow valve 672 for adjusting the flow rates of the high temperature medium H and the low temperature medium L flowing into the inlet pipe 611 are provided.
For this reason, for example, by adjusting the flow rate of the high-temperature medium H supplied to the furnace top gas heat exchanger 61 according to the temperature of the high-temperature medium H, a necessary amount of heat corresponding to the flow rate of the furnace top gas G to be temperature-adjusted can be obtained. , Can be supplied to the top gas G.

  The heat exchange state switching means 66 is provided so as to be switchable between a heat exchange state in which the heat exchange of the furnace top gas G and a non-heat exchange state in which no heat exchange is performed. For this reason, the top gas heat exchanger 61 can be used only when necessary, and the life of the top gas heat exchanger 61 can be extended.

  Since the heat medium switching means 67 is adjusted by the automatic control by the heat medium control means 693 and the heat exchange state switching means 66 is adjusted by the automatic control by the heat exchange control means 692, the load on the operator can be dealt with instantly and with good timing. Can be reduced.

[Modification]
In addition, this invention is not limited to the said embodiment, A concrete each part structure etc. can be suitably changed in implementation.
That is, two or more furnace top gas heat exchangers 61 are provided in accordance with the amount of heat given to the furnace top gas G by the furnace top gas heat exchanger 61 and the amount of heat recovered from the furnace top gas G by the furnace top gas heat exchanger 61. May be.
Further, without providing the furnace top gas flow rate measuring means 63, the first heat medium measuring means 64, and the second heat medium measuring means 65, the furnace top gas is measured based on the measurement result of the furnace top gas temperature measuring means 62. When the temperature of G is raised, the first heat medium inflow valve 671 and the first heat medium outflow valve 673 are fully opened, and when the temperature of the furnace top gas G is lowered, the second heat medium inflow valve 672 and the second heat medium outflow valve 674 may be fully opened.
Further, the top gas heat exchanger 61 may be provided in the bypass pipe 723 without providing the heat exchanger installation pipe 722, the heat switching valve 661, and the bypass valve 662.
An operator may open and close the heat switching valve 661 and the bypass valve 662 without providing the heat exchange control means 692. Further, without the heat medium control means 693 being provided, the operator can obtain the measurement results of the furnace top gas temperature measuring means 62, the furnace top gas flow rate measuring means 63, the first heat medium measuring means 64, and the second heat medium measuring means 65. Based on the above, the first heat medium inflow valve 671, the second heat medium inflow valve 672, the first heat medium outflow valve 673, and the second heat medium outflow valve 674 may be opened and closed.

  DESCRIPTION OF SYMBOLS 1 ... Dry type dust collection system, 2 ... Blast furnace, 3 ... Hot-blast furnace, 4 ... Fuel supply means, 5 ... Waste heat reuse system, 6 ... Furnace top gas temperature adjustment means, 7 ... Dust collection equipment, 21 ... Valve, 31 ... Chimney, 32 ... Blower, 33, 34 ... Valve, 41 ... Fuel gas supply means, 42 ... Combustion air supply means, 43, 44 ... Valve, 51 ... Exhaust gas heat exchanger, 52 ... Fuel gas heat exchanger, 53 ... Combustion air heat exchanger, 54 ... heat medium storage tank, 55 ... expansion tank, 56 ... circulation pump, 57 ... feed pump, 61 ... furnace top gas heat exchanger, 62 ... furnace top gas temperature measuring means, 63 ... furnace top gas Flow rate measuring means, 64 ... first heat medium measuring means, 65 ... second heat medium measuring means, 66 ... heat exchange state switching means, 67 ... heat medium switching means, 68 ... gas temperature measuring means after heat exchange, 69 ... control 71, dust remover, 72 ... dry dust collector, 201 ... piping, 311 ... Gas piping, 321 ... piping, 411 ... fuel gas piping, 421 ... combustion air piping, 511 ... high temperature pipe, 512 ... low temperature pipe, 541 ... piping, 551 ... piping, 611 ... inlet piping, 612 ... outlet piping, 641 ... heat Medium temperature measuring means, 642... Heat medium flow measuring means, 651... Heat medium temperature measuring means, 652... Heat medium flow measuring means, 661... Heat switching valve, 662 .. Bypass valve, 671. 2nd heat medium inflow valve, 673 ... 1st heat medium outflow valve, 674 ... 2nd heat medium outflow valve, 711 ... Piping, 721 ... Furnace top gas piping, 722 ... Heat exchanger installation pipe, 723 ... Bypass pipe, 724 ... pipe, E ... exhaust gas, G ... top gas, H ... high temperature medium, L ... low temperature medium, W ... hot air.

Claims (6)

A blast furnace,
A hot air furnace for supplying hot air to the blast furnace;
Fuel gas supply means and combustion air supply means for supplying fuel gas and combustion air to the hot stove;
An exhaust heat reuse system for reusing exhaust gas from the hot stove;
A furnace top gas temperature adjusting means for adjusting the temperature of the furnace top gas generated from the blast furnace;
A dry dust collector for removing dust in the furnace top gas;
A furnace top pressure recovery turbine driven by furnace top gas from the dry dust collector,
The exhaust heat reuse system includes:
An exhaust gas heat exchanger that is provided in the exhaust gas piping from the hot stove, performs heat exchange between the flowing heat medium and the exhaust gas, and flows out the heated heat medium;
A fuel gas pipe connecting the fuel gas supply means and the hot stove, and a combustion air pipe connecting the combustion air supply means and the hot stove, respectively, and a heating medium heated by the exhaust gas heat exchanger; A blast furnace composed of a fuel gas heat exchanger and a combustion air heat exchanger for heating the fuel gas and the combustion air between them to heat the cooled heat medium and flowing the cooled heat medium into the exhaust gas heat exchanger In the dry dust collection system for furnace top gas,
The furnace top gas temperature adjusting means includes:
A furnace top gas heat exchanger that is provided in a furnace top gas pipe that connects the blast furnace and the dry dust collector, performs heat exchange between the inflowing heat medium and the furnace top gas, and causes the heat medium to flow out.
A furnace top gas temperature measuring means for measuring the temperature of the furnace top gas before heat exchange in the furnace top gas heat exchanger;
A heat medium switching means for switching an inflow source of the heat medium and an outflow destination of the heat medium in the furnace top gas heat exchanger,
The heat medium switching means includes
Based on the measurement result of the furnace top gas temperature measuring means, the heated heating medium flowing out from the exhaust gas heat exchanger is caused to flow into the furnace top gas heat exchanger, and the heated heating medium that has been flown in is introduced. A heating state in which the furnace top gas is heated by heat exchange with the exhaust gas, and the deprived heat medium flows out to the exhaust gas heat exchanger, and after the desorption heat that flows out from the fuel gas heat exchanger and the combustion air heat exchanger The heat medium is allowed to flow into the furnace top gas heat exchanger, and the furnace top gas is cooled by heat exchange with the heat medium after deprived heat that has flowed in, and the heated heat medium is converted into the fuel gas heat exchanger. And a dry dust collection system for blast furnace top gas, which is configured to be switchable between a cooling state to flow out to the combustion air heat exchanger. In the blast furnace top gas dry dust collection system according to claim 1,
The heat medium switching means includes
A first heat medium inlet valve that adjusts the flow rate of the heated heat medium that flows out of the exhaust gas heat exchanger and flows into the furnace top gas heat exchanger;
A second heat medium inflow valve for adjusting the flow rate of the heat medium after heat removal flowing out of the fuel gas heat exchanger and the combustion air heat exchanger and flowing into the furnace top gas heat exchanger;
A first heat medium outlet valve that adjusts the flow rate of the heat medium after deprived heat that flows out of the furnace top gas heat exchanger and flows into the exhaust gas heat exchanger;
A second heat medium outlet valve that adjusts the flow rate of the heated heat medium that flows out from the furnace top gas heat exchanger and flows into the fuel gas heat exchanger and the combustion air heat exchanger,
The furnace top gas temperature adjusting means includes:
A furnace top gas flow rate measuring means for measuring a flow rate of the furnace top gas before heat exchange in the furnace top gas heat exchanger;
First heat medium measuring means for measuring the temperature and flow rate of the heated heat medium flowing into the first heat medium inflow valve;
And a second heat medium measuring means for measuring the temperature and flow rate of the cooled heat medium flowing into the second heat medium inflow valve, and a dry dust collection system for blast furnace top gas. In the blast furnace top gas dry dust collection system according to claim 2,
The furnace top gas temperature adjusting means includes:
When it is determined that the temperature measured by the furnace top gas temperature measuring means is less than a preset lower limit value, the heating medium switching means is set to the heating state, and is determined to be equal to or higher than a preset upper limit value. Then, comprising a heat medium control means for setting the heat medium switching means in the cooling state,
The heat medium control means includes
Based on the measurement results of the furnace top gas flow rate measuring means, the first heat medium measuring means, and the second heat medium measuring means, the first heat medium inflow valve, the second heat medium inflow valve, Blast furnace top gas dry type, wherein the flow rate of the heat medium flowing into the furnace top gas heat exchanger is adjusted by controlling the first heat medium outflow valve and the second heat medium outflow valve. Dust collection system. In the dry dust collection system of the blast furnace top gas according to any one of claims 1 to 3,
The furnace top gas pipe is
A heat exchanger installation pipe in which the furnace top gas heat exchanger is installed;
A bypass pipe connecting the blast furnace side with respect to the furnace top gas heat exchanger in the heat exchanger installation pipe and the dry dust collector side with respect to the furnace top gas heat exchanger;
The furnace top gas temperature adjusting means includes a heat exchange state in which the furnace top gas is circulated through the heat exchanger installation pipe to exchange heat of the furnace top gas, and the furnace top gas is circulated through the bypass pipe. A dry dust collection system for blast furnace top gas, comprising heat exchange state switching means for switching between a non-heat exchange state in which heat exchange of the top gas is not performed. In the blast furnace top gas dry dust collection system according to claim 4,
When the furnace top gas temperature adjusting means determines that the temperature measured by the furnace top gas temperature measuring means is less than a preset lower limit value or more than a preset upper limit value, the heat exchange state switching A heat exchange control means for setting the heat exchange state switching means to the non-heat exchange state when it is determined that the means is set to the heat exchange state and is not less than the lower limit value and less than the upper limit value. Blast furnace top gas dry type dust collection system. A blast furnace,
A hot air furnace for supplying hot air to the blast furnace;
Fuel gas supply means and combustion air supply means for supplying fuel gas and combustion air to the hot stove;
An exhaust heat reuse system for reusing exhaust gas from the hot stove;
A dry dust collector for removing dust in the furnace top gas;
A furnace top pressure recovery turbine driven by furnace top gas from the dry dust collector,
The exhaust heat reuse system includes:
An exhaust gas heat exchanger that is provided in the exhaust gas piping from the hot stove, performs heat exchange between the flowing heat medium and the exhaust gas, and flows out the heated heat medium;
A fuel gas pipe connecting the fuel gas supply means and the hot stove, and a combustion air pipe connecting the combustion air supply means and the hot stove, respectively, and a heating medium heated by the exhaust gas heat exchanger; A blast furnace composed of a fuel gas heat exchanger and a combustion air heat exchanger for heating the fuel gas and the combustion air between them to heat the cooled heat medium and flowing the cooled heat medium into the exhaust gas heat exchanger A dry dust collection method using a dry dust collection system for furnace top gas,
In the dry dust collection system,
A furnace top gas heat exchanger that is provided in a furnace top gas pipe that connects the blast furnace and the dry dust collector, performs heat exchange between the inflowing heat medium and the furnace top gas, and causes the heat medium to flow out.
A furnace top gas temperature measuring means for measuring the temperature of the furnace top gas before heat exchange in the furnace top gas heat exchanger;
A heat medium switching means for switching a heat medium inflow source and a heat medium outflow destination in the furnace top gas heat exchanger,
When it is determined that the temperature measured by the furnace top gas temperature measuring means is less than a preset lower limit value, the heated heating medium flowing out from the exhaust gas heat exchanger is caused to flow into the furnace top gas heat exchanger. Then, the furnace top gas is heated by heat exchange with the heated heating medium that has been allowed to flow, and the heat medium that has been deprived is set to a heating state that flows out to the exhaust gas heat exchanger,
When it is determined that the value is equal to or higher than a preset upper limit value, the heat medium after heat removal flowing out from the fuel gas heat exchanger and the combustion air heat exchanger is caused to flow into the furnace top gas heat exchanger. The furnace top gas is cooled by heat exchange with the deprived heat medium that has been removed, and the heated heat medium is set in a cooling state that flows out to the fuel gas heat exchanger and the combustion air heat exchanger. A dry dust collection method.

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