JPS63140015A - Smelting reduction refining equipment - Google Patents

Abstract

PURPOSE:To provide titled equipment which optimizes the excess energy to be discharged into a lower stage and does not require large-scale equipment investment for production of O2 by constituting the equipment in such a manner that the energy possessed by the exhaust gas generated in a smelting reduction furnace is repeatedly used as far as possible within its own process. CONSTITUTION:The energy possessed by the exhaust gas of the smelting reduction furnace 1 is utilized from its sensible heat first. Namely, a steam turbine 20 is driven by the steam formed by said sensible heat. The exhaust gas emitted from a steam generating means is then compressed by an exhaust gas compressing means 23 and air is compressed by air compressing means 25, 27. A gas turbine 24 is driven by the combustion gas obtd. by burning 21 such high-pressure exhaust gas and high- pressure air. The flow rate of the exhaust gas to be introduced into the means 23 is so controlled that the sum of the driving power for driving the means 25, 27 and the means 23 and the required driving power of the turbines 24 and 20 such as, for example, the driving power required for production of gaseous O2 coincides with the output of the two turbines. As a result, the max. exhaust gas energy is used within its own process of the smelting reduction of the furnace and the exhaust gas to be discharged to the lower stage is minimized.

Description

Detailed Description of the Invention [Industrial Field of Application] This invention is a smelting reduction method in which iron ore is blown into molten pig iron in a smelting furnace together with coal and lime, and oxygen gas is blown into the molten pig iron through a lance and a bottom tuyere. The present invention relates to smelting equipment, and more specifically, relates to smelting-reduction smelting equipment that utilizes the energy of exhaust gas generated during smelting to the maximum extent possible in its smelting-reduction smelting operation.

[Conventional technology 1] The smelting reduction refining method is an alternative to the blast furnace iron manufacturing method, and in order to eliminate the disadvantages of the blast furnace iron manufacturing method, such as the high construction cost of the blast furnace and the need for a vast site, It has been developed in recent years. In such a smelting reduction smelting method, pre-reduced ore, powdered coal and lime are injected into the hot metal in the smelting furnace through a tuyere provided at the bottom of the furnace, and oxygen gas is injected into the hot metal from another tuyere. At the same time, oxygen gas is blown into the hot metal from the top of the furnace through a lance inserted into the furnace. Then, the coal is dissolved in the hot metal, and the carbon in the coal is oxidized by the oxygen gas. The ore is melted by this oxidation heat, and the ore is reduced by the carbon in the coal. CO gas generated from hot metal is secondary combusted by oxygen gas blown from a lance and becomes CO2 gas. The sensible heat of this CO2 gas is transferred to the forming slag covering the hot metal, and then returned to the hot metal.

[Problems to be Solved by the Invention] By the way, in this melting reduction process, a large amount of oxygen gas is used. Conventionally, oxygen gas is produced by sending the gas generated in the melting reduction process to a power plant, generating electricity with the gas, and driving a compressor using the electricity. However, in the past, in order to produce this large amount of oxygen gas, it was necessary to install a large-capacity power plant and maintain a piping system, which resulted in the problem of requiring large-scale capital investment. be.

This invention was made in view of such circumstances, and
The energy of the exhaust gas generated in the smelting reduction furnace can be repeatedly used in the own process as much as possible, and the surplus energy discharged to the downstream process can be appropriated, making it possible to directly produce oxygen gas in the own process, and improving oxygen production. The purpose of the present invention is to provide a smelting reduction refining facility that can avoid large-scale capital investment.

[Means for Solving the Problems] The smelting reduction refining equipment according to the present invention includes a steam generating means that generates steam using sensible heat contained in the exhaust gas of the smelting reduction furnace, and an exhaust gas that introduces and compresses a part of the exhaust gas. compression means;
An air compression means for compressing air, a steam turbine driven by steam from the steam generation means, a combustion means for introducing and combusting high pressure exhaust gas from the exhaust gas compression means and high pressure air from the air compression means, and a combustion means. to the exhaust gas compression means so that the required power of the gas turbine and the steam turbine is obtained by subtracting the power of the exhaust gas compression means and the air compression means from the output of the gas turbine and the steam turbine. and adjusting means for adjusting the amount of exhaust gas introduced.

[Operation] In this invention, the energy of the exhaust gas of the smelting reduction furnace is first utilized from its sensible heat. In other words, this sensible heat is used to generate steam, and this steam drives a steam turbine. Next, the exhaust gas compression means compresses the exhaust gas discharged from the steam generation means, and the air compression means compresses the air. These high-pressure exhaust gases and high-pressure air are combusted by combustion means, and the gas turbine is driven by this combustion gas. The sum of the power for driving the exhaust gas compression means and the air compression means and the power required for the gas turbine and the steam turbine, such as the power required for producing oxygen gas, matches the output of the gas turbine and the steam turbine. In addition, the adjusting means adjusts the amount of exhaust gas introduced into the exhaust gas compression means. Thereby, maximum exhaust gas energy can be used within the self-process of melting and reduction, and exhaust gas discharged to downstream processes can be minimized.

Embodiment 1 FIG. 1 is a block diagram showing a smelting reduction refining facility according to an embodiment of the present invention, and FIG. 2 is a block diagram showing an oxygen separation device thereof. High-temperature exhaust gas generated in the melting reduction furnace 1 is sent to the preliminary reduction furnace 2 and used for preliminary reduction of ore. The exhaust gas discharged from this preliminary reduction furnace 2 is collected by a dust collector 3.
After removing dust, it is sucked in by a blower 8, passes through a heat exchanger 4, a high pressure boiler 5, an intermediate pressure boiler 6, and a decarbonation gas device 7 in this order, and a part of it is discharged to the downstream process. .

A high pressure boiler 14 is installed in the exhaust gas flue 15 between the smelting reduction furnace 1 and the preliminary reduction furnace 2, and the radiant heat of the exhaust gas from the smelting reduction furnace 1 is recovered as high pressure steam by the high pressure boiler 14. This high pressure steam is supplied to the steam turbine 20.

A portion of the exhaust gas exiting the decarbonization device 7 is supplied to the heat exchanger 4 by a blower 9 . This exhaust gas is heated in the heat exchanger 4 by the sensible heat of the exhaust gas from the preliminary reduction furnace 2, and then supplied to the melting reduction furnace 1 via the hopper 10. Powdered dry coal is stored in the hopper 10 , and this coal is carried by the exhaust gas from the heat exchanger 4 and blown into the melting reduction furnace 1 .

A portion of the exhaust gas exiting the high-pressure boiler 5 is introduced into the coal drying device 11, and the coal is dried by the sensible heat of this exhaust gas. This dried coal is collected in a hopper 10,
The exhaust gas after drying the coal is introduced into a decarbonization device 7.

The exhaust gas leaving the heat exchanger 4 is supplied to the high pressure boiler 5,
The sensible heat of the exhaust gas is used to produce high-pressure steam. The steam produced in this high pressure boiler 5 is transferred to the steam turbine 2o.
supplied to

The exhaust gas leaving the high pressure boiler 5 is supplied to the intermediate pressure boiler 6, and the sensible heat of the exhaust gas is used to produce intermediate pressure steam. The steam produced in the intermediate pressure boiler 6 is transferred to the steam turbine 2
0.

The exhaust gas exiting the medium pressure boiler 6 is introduced into a decarbonation device 7. The exhaust gas from the smelting reduction furnace is approximately 20 to 50% carbon dioxide gas (CO2) and approximately 5 to 20% hydrogen gas (H2 gas).
about 30 to 50% carbon monoxide gas (CO gas). Among these constituent gases, CO2 gas does not contribute to combustion in the combustor 21, which will be described later, so this CO2 gas is removed by the decarboxylation device 7.

The exhaust gas exiting the collection 11vs3 is supplied not only to the heat exchanger 4 but also to the high pressure boiler 12. In this high-pressure boiler 12, the sensible heat of the exhaust gas is used to produce high-pressure steam. The exhaust gas leaving the high-pressure boiler 12 is introduced into the ore humidity control device 13, and the sensible heat of the exhaust gas is used to dry the ore. In the ore drying device 13, the ore is dried to a predetermined moisture content by the sensible heat of the exhaust gas. The ore after humidity control is supplied to the pre-reduction furnace 2 and pre-reduced. The exhaust gas after ore humidity control is introduced into a decarbonation gas device 7.

A part of the exhaust gas leaving the decarbonation device 7 is passed through a control valve 22 to an exhaust gas compressor 23 such as an axial flow compressor.
After being compressed by this compressor 23, it is supplied to the combustor 21. This exhaust gas compressor 2
3 is driven by the driving force of a steam turbine 20 and a gas turbine 24. The control valve 22 is controlled to open and close by the control device 19.

Air compressor 25 compresses air and supplies high pressure air to combustor 21 . In the combustor 21, high-pressure exhaust gas and high-pressure air are mixed and combusted.
cm2) of combustion gas is supplied to the gas turbine 24 to drive the gas turbine 24. The combustion gas after driving the gas turbine 24 has a temperature of about 650 to 700°C (
The pressure is 0.1 k (1/cm2), and this combustion gas is supplied to two medium pressure boilers and used to produce medium pressure steam. After leaving the medium pressure boiler 28, the combustion gases are discharged.

The steam turbine 20, the gas turbine 24, and the air compressor 25 are all installed with their drive shafts connected. Therefore, the air compressor 25 is connected to the steam turbine 2
0 and a gas turbine 24. Furthermore, the drive shafts of a synchronous generator 26 and an air compressor 27 are also connected to the drive shafts of the steam turbine 20 and the gas turbine 24 . Therefore, the steam turbine 20 and the gas turbine 24 are driven by the synchronous generator 26 powered by an appropriate power source (not shown) at startup, and in a steady state,
The synchronous generator 26 is connected to the steam turbine 20 and the gas turbine 2
4 to generate electricity.

The air compressor 27 compresses air and supplies this high-pressure air to an oxygen separation device 30 using a so-called cryogenic separation method.
The oxygen separation device 30 separates oxygen gas from high pressure air,
This oxygen gas is supplied to the melting reduction furnace 1.

The oxygen valve 111 device 30 is connected to the cooling 1 as shown in FIG.
31 and a distillation column 32, the air compressed by the air compressor 27 is cooled by the cold filter 1 machine 31 and becomes liquid air. This liquid air is supplied to a distillation column 32, where oxygen and nitrogen are separated due to the difference in boiling point between nitrogen and oxygen. For example, oxygen accumulates in the lower layer of the distillation column 32, and nitrogen accumulates in the upper layer.

In the smelting reduction smelting equipment configured in this way, part of the sensible heat of the exhaust gas generated during smelting in the smelting reduction furnace 1 is used for preliminary reduction of ore in the preliminary reduction furnace 2, and then The dust is cleaned by the dust collector 3 and sent to the heat exchanger 4. In this case, in the flue 15, the radiant heat of the exhaust gas is recovered as high pressure steam by the high pressure boiler 14, and this high pressure steam is supplied to the steam turbine 20. An obvious part of the exhaust gas is transferred to the heat exchanger 4 by C from the decarbonization gas unit @7.
Used to heat exhaust gas (Co and H2 gas) that does not contain O2 gas. Powdered coal in hopper 1o is transferred to heat exchanger 4
It is blown into the melting reduction furnace 1 while being carried by CO and H2 gases from the reactor.

The sensible heat of the exhaust gas is recovered as steam by the high pressure boilers 5, 12 and the intermediate pressure boiler 6, and the high pressure and intermediate pressure steam are supplied to the steam turbine 20 and used to drive it.

In the coal drying device 11, a part of the exhaust gas exiting the high pressure boiler 5 is introduced to dry the coal.

The dried coal is supplied to the hopper 10 and stored therein, and the exhaust gas is supplied to the decarbonizer 7.

The exhaust gas exiting the high-pressure boiler 12 is supplied to the ore humidity control device 13 and used for drying the ore, and then supplied to the decarbonation gas device 7. The ore whose moisture content has been adjusted is charged into a preliminary reduction furnace 2 and subjected to preliminary reduction.

CO2 gas is removed from the exhaust gas in a decarbonization device 7. A part of the exhaust gas consisting of CO gas and H2 gas is sent to the combustor 2 while its flow rate is adjusted by the control valve 22.
3. The air compressor 25 is driven by a synchronous generator 26 when starting up, and is driven by the gas turbine 24 and the steam turbine 20 in a steady state.

High pressure air compressed by the air compressor 25 is supplied to the combustor 21. In the combustor 21, high-pressure exhaust gas and compressed air are mixed and combusted, and the high-pressure hot water (for example, 1150 to 1200°C and 16 klll/
cm2) of combustion gas is supplied to the gas turbine 24 to drive the gas turbine 24.

Since the exhaust gas supplied to the combustor 21 does not contain carbon dioxide gas, which is a non-combustion gas, it has a high calorific value, and the combustion gas drives the gas turbine 24 with high efficiency. The gas turbine 24 is driven by a synchronous generator 26 at startup, and is driven by high-temperature, high-pressure combustion gas from the combustor 21 in a steady state.

The combustion gas exiting the gas turbine 24 is supplied to an intermediate pressure boiler 28 to produce intermediate pressure steam, and this steam is supplied to the steam turbine 20. Steam exiting the steam turbine 20 is collected in a condenser 29 and used for circulation. Steam turbine 20 and gas turbine 24 drive air compressor 27 .

Air compressor 27 supplies compressed air to oxygen separator 30 . On the other hand, in a steady state, the synchronous generator 26 is also driven by the gas turbine 24 and the steam turbine 20, and this synchronous generator 26 functions as a generator. In the oxygen separation device 30, compressed air is cooled by a cooler 31 and becomes liquid air. This liquid air is separated in the distillation column 32 based on the difference in boiling point, and the obtained oxygen gas is supplied to the melting reduction furnace 1. Thereby, the oxygen gas used for refining in the smelting reduction furnace 1 is produced using the exhaust gas of the smelting reduction furnace 1, and investment in a power plant for oxygen gas production is avoided.

The control device 19 controls the exhaust gas liF supplied to the exhaust gas compressor 23 via the control valve 22 as follows.
Determine by trial and error. That is, the control device 19 first assumes the exhaust gas amount, the steam turbine efficiency, and the gas turbine efficiency to appropriate values.

Next, the control device 19 calculates the required power P2 of the exhaust gas compressor 23 and the air compressor 25 at this flow rate and efficiency, and also calculates the output P1 of the steam turbine 20 and the gas turbine 24. In this case, the balance of energy in the heat exchanger 4, the high pressure boilers 2 and 12, and the intermediate pressure boiler 6 is uniquely calculated. And the control equipment! 119 judges whether the value obtained by subtracting the power P2 from the output P1 (Pl-P2) matches the power Pa required in the melting reduction process. This required power Pa
These include the power of the suction blowers 8 and 9, the driving force of the synchronous generator 26, the driving force of the air compressor 27, etc. The driving force of the air compressor 27 is used as the power to produce the required amount of high-pressure air to the oxygen separation device 30 (the amount required for the oxygen separation device M30 to produce the oxygen gas necessary in the smelting reduction furnace 1). Calculated. control! l device 19 is Pt-P2
If it does not match Pa, correct the exhaust gas flow IF to the exhaust gas compressor 23 and recheck PL, P2, P
Calculate a. In this way, the control device 19 determines that the required power P2 of the air compressor 25 and the exhaust gas compressor 23 is subtracted from the sum P1 of the output of the gas turbine 24 and the output of the steam compressor 20. The amount F of exhaust gas passing through the regulating valve 22 is calculated when it matches the required power of 20, and the regulating valve 22 is controlled to this exhaust gas flow IF.

When the flow rate of the control valve 22 is determined in this manner, the flow rate of the exhaust gas discharged to the lower process is determined.

If the flow rate discharged to the lower process does not match the required amount of exhaust gas in the lower process, the settings of each furnace operating condition may be changed to determine the optimum operating conditions.

Next, another embodiment of the present invention will be described with reference to FIG. This embodiment differs from the embodiment shown in FIG. 1 in that oxygen gas is produced by chemical adsorption. In FIG. 3, the same components as those in FIG. 1 are given the same reference numerals and their explanations will be omitted. Combustion gas leaving the gas turbine 24 is discharged via a heat exchanger 35 and an intermediate pressure boiler 28.

As shown in FIG. 4, in the oxygen gas production device 40, air is sent to a filter 42 by a blower 41, and after dust is collected by this filter, the air is heated to 480 to 500°C by heat exchangers 43 and 44. After being heated, it is supplied to the absorption tower 45. The absorption tower 45 contains KN, which is a gas absorbing material.
O2 liquid is supplied, and this KNO2 has a temperature of 480 to 500'C, as shown in equation (1) below.
KNO is absorbed by absorbing oxygen O2 gas from the air at a relatively low temperature.
s (alkali nitrate).

KNO2+02-KNO3 (480 to 500℃) ... (1) KNO3=KN
○2+02 (600 to 650°C) ...<2) This KNO3 is heated in the heat exchanger 46, and further heated to 600°C by the heat exchanger 35.
KNO3 heated by this heat exchanger 35 is sent to a regeneration tower 47 under reduced pressure, and in this regeneration tower 47, KNO3 is decomposed according to the above formula (2) and becomes oxygen gas. is manufactured.

In this second embodiment, the combustion gas used to drive the gas turbine 24 is used as a high temperature source in the heat exchanger 35 and then used in the intermediate pressure boiler 28 to produce intermediate pressure steam. After that, it is discharged.

On the other hand, in the oxygen gas production device 40, air is sent to the filter 42 by the blower 41, and the air is sent to the heat exchanger 43.
44 and sent to an absorption tower 45.

In the absorption tower 45, the K sent from the regeneration tower 47 is
NO2 and air react at 480-500°C and oxygen gas in the air is absorbed into this gas absorbing material. The remaining nitrogen gas exchanges heat with air in the heat exchanger 44, is cooled by a cooler 549, and is discharged. KNO3 that has absorbed oxygen gas is heated in a heat exchanger 46, heated in a heat exchanger 35, and sent to a regeneration tower 47 under reduced pressure. In the regeneration tower 47, the KNO3 releases oxygen gas at a relatively high temperature of 600 to 650°C, and the KNO2 is returned to the absorption tower 45 via the heat exchanger 46, and the sensible heat of the oxygen gas is transferred to the heat exchanger 43. After being used to heat the air, it is cooled by a cooler 48 and sent to the melting reduction furnace 1.

According to these examples, oxygen gas with a purity of 99.9% is obtained, and this oxygen gas is used as a refining gas in the smelting reduction furnace 1. In the melt reduction process, approximately 452
a+3/hour of oxygen gas is required, and in this example, the entire amount of oxygen gas is supplied to the oxygen gas production device (r1
Since it is produced in the single element separation device 30 and the oxygen gas production bag [40], there is no need to use a conventional oxygen gas production plant using electricity, and there is no need to invest in a power plant.

Note that it is preferable that the high-pressure air supplied to the combustor 21 is also heated. This high-pressure air can be heated by guiding the high-pressure air exiting the air compressor 25 to a heat exchanger using exhaust gas or combustion gas, and heating the high-pressure air in this heat exchanger.

[Effect of the invention] According to the present invention, by repeatedly using the energy of the exhaust gas generated in the smelting-reduction furnace in the smelting-reduction process as much as possible, the energy discharged to the downstream process can be reduced to the minimum required by the downstream process. can be limited. In addition, oxygen gas with high added value can be produced using the combustion heat obtained by burning the exhaust gas generated in the smelting reduction process and the sensible heat of the exhaust gas, so the oxygen gas used in the smelting reduction furnace can be The entire amount can be self-supplied and investment in power plants can be avoided.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing an embodiment of this invention, Fig. 2 is a block diagram showing its oxygen separation device, Fig. 3 is a block diagram showing another embodiment of this invention, and Fig. 4 is its oxygen gas It is a block diagram showing a manufacturing device. 1; Melting reduction furnace; 2; Pre-reduction furnace; 4: Heat exchanger; 5.
6.12.28: Boiler, 7; Decarbonization device, 11:
Coal drying device, 13; Ore II wet device, 20; Steam turbine, 21: Combustor, 22; Control valve, 23; Compressor, 24 Gas turbine, 25.27: Air compressor, 30; Oxygen separation device, 35: Heat exchanger, 40; Oxygen gas production equipment applicant's representative Patent attorney Takehiko Suzue Kenkiko〉71ㅅsa27J) U2 Fig. 2 Fig. 4

Claims (1)

[Claims] A steam generation means that generates steam using the sensible heat of the exhaust gas of the smelting reduction furnace, an exhaust gas compression means that introduces and compresses a part of this exhaust gas, an air compression means that compresses air, and a steam generation means that generates steam from the steam generation means. a driven steam turbine;
A combustion means that introduces and burns high-pressure exhaust gas from the exhaust gas compression means and high-pressure air from the air compression means, a gas turbine driven by the combustion gas from the combustion means, and an exhaust gas compression means from the output of the gas turbine and the steam turbine. and an adjustment means for adjusting the amount of exhaust gas introduced into the exhaust gas compression means so that the power required for the gas turbine and the steam turbine is obtained by subtracting the power from the air compression means. .