CN1330162A

CN1330162A - Process and equipment for preparing spongy iron by two-step reduction method

Info

Publication number: CN1330162A
Application number: CN 01123771
Authority: CN
Inventors: 雷少军
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-07-31
Filing date: 2001-07-31
Publication date: 2002-01-09
Anticipated expiration: 2021-07-31
Also published as: CN1159460C

Abstract

A process and equipment for preparing spongy iron by two-step reduction method is disclosed. The tail gas is pumped from the top of vertical reducing furnace to transform heater, where the tail gas reacts on the solid carbon to obtain the reducing gas whose main component is CO and the excess gas. Said reducing gas is returned back to said vertical reducing furnace to form a circulation. Said excess gas can be used as fuel. Its advantages include full use of energy resource, less environmental pollution and low cost.

Description

Process and equipment for producing sponge iron by two-step reduction method

Technical Field

The invention relates to a process method and equipment for producing sponge iron by a two-step reduction method.

Background

At present, the process for producing sponge iron can be roughly divided into two types, namely a gas-based method and a coal-based method. The gas-based method is a process method for reducing iron oxide in a reducing furnace after heating reducing gas, and the metallization rate of the sponge iron produced by the method is high and can reach more than 92 percent, but the method has the defects thatThe method has the advantages that the investment is large, more than 50% of effective gas in the reduced tail gas is discharged, energy is wasted, and environmental pollution is caused; the coal-based method is a method of mixing and charging coal or coke and iron oxide ore in a container and externally heating to reduce the iron oxide ore, and has the advantages of small investment and quick response, but has the problems of poor product quality, high production cost, serious pollution and the like. Both the two methods have the defects of low energy utilization rate and environmental pollution caused by tail gas emission, although people use the waste gas generated in the reduction process to generate electricity, the heat energy utilization rate is less than 10 percent, and the method has little practical significance and does not solve the problem of tail gas pollution. For example, Chinese patent 96190922 discloses a method for producing austria sponge iron, which mainly comprises discharging CO in the tail gas from the reduction furnace₂The gas is removed by pressure swing adsorption, and then is used as heat source to supply to heating device, its heat energy utilization rate is low, and in addition, it also has need of adding correspondent equipment to provide a certain quantity of oxygen-containing gas. In conclusion, if the exhaust emission and utilization of the tail gas cannot be solved well, the energy utilization rate cannot be improved, and the environmental protection is only a word.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a process method for producing sponge iron and equipment for implementing the process method, which can recycle tail gas generated in a reduction shaft furnace and fully utilize energy sources, thereby reducing the pollution to the environment and greatly reducing the production cost.

In order to accomplish the task of the invention, the process method for producing the sponge iron comprises the following steps: reacting the iron oxide-containing ore with reducing gas in a reduction shaft furnace, reducing the iron oxide-containing ore into sponge iron, and outputting the reacted furnace top tail gas by the reduction shaft furnace; the process method of the invention also comprises the following steps:

a. the furnace top tail gas is output from the reduction shaft furnace and then divided into two paths, wherein one path is sent into a reduction cavity of the heating conversion furnace through a fan and a pipeline, and the other path is sent into a combustion chamber of the heating conversion furnace through a pipeline;

b.1) CO in the top gas fed into the reduction chamber₂Reacting with the solid carbon carrier in the cavity, wherein the reaction formula is as follows:

the generated components are CO 80-92% and CO₂6-18% of reducing gas with 2% of other component gas, wherein the reducing gas is conveyed to the reduction shaft furnace through a pipeline so as to form gas circulation, the temperature in the reduction cavity is 800-1000 ℃, and the temperature of the reducing gas conveyed to the reduction shaft furnace from the reduction cavity is 570-900 ℃;

2) the furnace top tail gas sent into the combustion chamber is mixed with oxygen-containing gas in the combustion chamber and then is combusted, and heat energy is provided for the reduction cavity:

c. before the whole system is started, firstly, CO is filled into the system through an inflation inlet and an exhaust outlet₂Gas or CO₂Replacing air in the system with the mixed gas of CO, then closing an air charging port and an air exhaust port, starting a fan, igniting a heating combustion chamber of a heating conversion furnace to rapidly heat the reduction cavity to 800-1000 ℃, starting the system and circularly operating;

d. when the system stops operating, the system is closed, and reducing gas in the system is discharged to ensure the safety of the system.

After being output, the furnace top tail gas output from the reduction shaft furnace is washed by a washing device and then divided into two paths, wherein one path is sent to a reduction cavity of the heating conversion furnace by a fan and a pipeline, and the other path is sent to a combustion chamber of the heating conversion furnace by a pipeline.

After being output, the furnace top tail gas output from the reduction shaft furnace is washed by a washing device and then divided into two paths, one path is sent into a reduction cavity of the heating conversion furnace by a fan and a pipeline, the other path is firstly sent into a gas storage cabinet, and after the gas storage cabinet is filled with the furnace top gas, the furnace top gas is sent into a combustion chamber of the heating conversion furnace by an output pipeline of the gas storage cabinet.

In order to ensure the efficient operation of the system, the pressure of 0.4-0.8 MPa should be maintained in the reduction cavity, and the pressure of 0.2-0.3MPa should be maintained in the gas storage tank.

The iron oxide-containing ore is pellet ore and/or lump ore containing Fe of more than or equal to 64%.

The solid carbon carrier is coke and/or coal with the fixed carbon content of more than or equal to 80 percent.

The temperature in the reduction cavity is 900 ℃, the temperature of the reducing gas input into the reduction shaft furnace is 850 ℃, and the componentsof the reducing gas are CO 91% and CO ₂7% and other component gases 2%; the components of the furnace top tail gas are CO 55% and CO₂43% and other component gas 2%.

Before the system is started for the first time, the CO charged into the system is charged through the charging port and the exhaust port₂For industrial use of CO₂A gas; and c: CO in the gas storage cabinet is used through the inflation inlet and the exhaust outlet₂And the CO mixed gas is replaced by other gases in the system.

An apparatus for carrying out the process comprises a reduction shaft furnace which has a reducing gas inlet and a furnace top tail gas outlet and can be continuously charged and discharged in a closed state; the device also comprises a heating converter, the heating converter is composed of a gas reduction cavity and a heating part thereof, the gas reduction cavity is positioned above the flame heating combustion chamber, the reduction cavity is provided with a gas inlet, a gas outlet, a feed inlet and a discharge outlet, the reduction cavity can continuously feed and discharge materials in a closed state, the heating part is provided with a flame heating combustion chamber, and the combustion chamber is provided with a furnace top tail gas input port, an oxygen-containing gas input port and a waste gas discharge port; the furnace top tail gas output pipeline connected with the furnace top tail gas outlet of the reduction shaft furnace is divided into two paths, one path is communicated with the reduction cavity of the heating reforming furnace through a fan and a pipeline, the other path is communicated with the combustion chamber of the heating reforming furnace through a pipeline, and the pipeline is connected with an external gas input port and a system gas outlet; and a gas outlet of the reduction cavity is communicated with a reducing gas inlet of the reduction shaft furnace through a pipeline.

The process method of the invention adopts the mode of recycling the reducing gas to produce the sponge iron, the tail gas at the top of the reduction shaft furnace is not discharged in the production process, and the residual gas generated by the reaction in the system is fully utilized as the fuel, so the process method of the invention not only reduces the pollution to the environment, but also greatly reduces the production cost.

Drawings

The invention will be further explained with reference to fig. 1 and 2.

FIG. 1 is a diagram of a process flow and system for carrying out the process of the present invention;

FIG. 2 is a diagram showing a system configuration in the process flow without a cleaning step and without a gas holder;

FIG. 3 is a schematic view of a heating reformer used in the apparatus of the present invention.

Detailed Description

Example 1

As shown in FIG. 1, the present invention comprises a two-step reduction reaction, one step reduction reaction being carried out in a reduction shaft furnace 2, a two-step reduction reaction being carried out in a heating reformer 1, the one-step reduction reaction reducing iron oxide to metallic iron, and the two-step reduction reaction reducing CO₂Reduction to CO is as follows:

before the whole system starts to operate, coke and/or coal with the fixed carbon content of more than or equal to 80 percent is added into a reduction cavity 20 of the heating conversion furnace 1 through a feeding hole 13, and CO is charged into the system through a charging hole 12 and an exhaust hole 11₂The air in the system is replaced, the air charging and

discharging ports

12 and 11 are closed, the

valves

5, 6 and 7 are opened, the combustion chamber 21 of the heating conversion furnace 1 is ignited, the fan 3 and other devices are started, and the system starts to operate circularly.

The reduction chamber 20 is heated to 900 ℃ by the combustion chamber 21, and CO in the reduction chamber 20₂And the coke and/or coal in the cavity are subjected to reduction reaction, and the reaction equation is as follows:

after the reaction, a reducing gas is generated, theThe reducing gas contains CO 91% and CO ₂7% and other component gases 2%; the reducing gas is fed into the reduction shaft furnace 2 through a duct 8 to reduce the iron ore in the reduction shaft furnace 2, and the temperature of the reducing gas fed into the reduction shaft furnace 2 is 850 ℃.

Iron oxide-containing raw material, preferably pellets or briquettes with an Fe content of 64% or more, which is fed into the reduction shaft furnace 2 from a feed opening 17 in a known manner; the reducing gas fed into the reduction shaft furnace 2 flows in opposite directions with the downward iron ore flow and undergoes a one-step reduction reaction with the iron oxide in the ore, the reacted gas flows through the reduction shaft furnace 2 and is output as top tail gas, and sponge iron and waste slag generated by the reaction are discharged through

pipelines

18 and 19 respectively.

The furnace top tail gas output by the reduction shaft furnace 2 is sent into the washer 4 for washing through a pipeline 26, the washed clean tail gas is output from the washer 4 through a pipeline 27 and then divided into two paths, one path is sent into the reduction cavity 20 througha pipeline 9 after passing through the fan 3 for two-step reduction, and the reduction gas generated after the reduction reaction continuously participates in gas circulation; one path is sent to a gas storage cabinet 25 through a pipeline, and after the gas storage cabinet 25 is filled with the furnace top tail gas, the gas storage cabinet 25 is sent to a combustion chamber 21 through a pipeline 10; wherein the top gas fed into the reduction chamber 20 accounts for about 72% to about 76% of the total amount of the top gas; the gas pressure in the reduction cavity 20 is 0.8MPa, and the gas pressure in the gas storage holder 25 is 0.2-0.3 MPa; the tail gas part sent to the combustion chamber 21 is a gas volume increasing part in the system, and the volume of the furnace top gas sent into the reduction cavity 20 is increased by about 35 percent after two-step reduction reaction; this portion of the added gas is referred to as the balance gas. The volume of the gas of the whole system is increased by the residual gas generated in the two-step reduction reaction, and the gas enters the reduction shaft furnace 2 to form the top tail gas, under the condition of maintaining the balance of the circulating gas in the system, a part of the top tail gas enters the gas storage cabinet 25, after the gas storage cabinet 25 is filled with the top tail gas, the top tail gas is sent into the combustion chamber 21 from the gas storage cabinet 25 and mixed and combusted with the oxygen-containing gas fed from the input port 15 to provide heat for the reduction cavity 20, and the combusted waste gas in the combustion chamber 21 is discharged through the discharge port 16; the fuel to be burned in the combustion chamber 21 is also industrial heavy oil.

The components of the furnace top tail gas output by the reduction shaft furnace 2 are CO55 percent and CO₂43% and other component gas 2%.

The waste residue after reaction in the reduction cavity 20 is discharged from the discharge hole 14, and the heating converter 1 can continuously feed and discharge materials in a closed state.

After the system stops operating, the reducing gas in the system is discharged to ensure the safety of the system. Before restarting, using CO stored in gas holder 25₂And replacing the gas in the system by the mixed gas of CO, starting the system and enabling the system to circularly operate again.

Example 2

As shown in fig. 2, the system of embodiment 1 may not be provided with a furnace top tail gas cleaner and a gas storage holder, at this time, the furnace top tail gas output by the reduction shaft furnace 2 is output by a pipeline 26 and then divided into two paths, one path of the furnace top tail gas is sent into the reduction cavity 20 by a pipeline 9 after passing through a fan 3 for two-step reduction, and the reduction gas generated after the reduction reaction continues to participate in gas circulation; one is fed by the duct 10 to the combustion chamber 21.

As shown in fig. 3, the heating reformer 1 includes a gas reducing chamber 20 and a combustion chamber 21; the reduction cavity 20 is filled with coke and/or coal, is provided with a gas input 24, an output port 23 and a gas inlet and

outlet

13 and 14, and is hermetically sealed; the combustion chamber 21 has a feed 22 for top tail gas and a feed 15 for other fuels and oxygen-containing gases. The parameters of the system during operation are as follows:

name (R)	Specification of	Unit of	Quota of consumption (per ton product)	Consumption of
				Consumption of		Per hour of the product	Each year
				Iron ore	The Fe content is more than or equal to 64 percent	Per hour of the product	Each year	Ton of	1.43	19.86	143000
Coke or coal	Fixed carbon content not less than 80%, ash content Not more than 14 percent of sulfur, not more than 0.71 percent of sulfur	Ton of	0.40	Iron ore	The Fe content is more than or equal to 64 percent	5.56	40032	Ton of	1.43	19.86	143000
Coke or coal		Ton of	0.40	Water (W)	Can be recycled	5.56	40032	Ton of	1	14	100000
Electric power		Degree of rotation	80	Water (W)	Can be recycled	1112	8000000	Ton of	1	14	100000
Electric power		Degree of rotation	80	Heavy oil	Industrial product	1112	8000000	Kg	9	125	900000
Pure CO₂	The original vehicle is started for one-time charging, and the pressure is as follows: 0.2Mpa							Kg	9	125	900000

Claims

1. A process for producing sponge iron by a two-step reduction method, wherein ores containing iron oxide are reduced into sponge iron after reacting with a reducing gas in a reduction shaft furnace (2), and the reduction shaft furnace (2) outputs the reacted furnace top tail gas, is characterized in that:

a. the furnace top tail gas is output from the reduction shaft furnace (2) and then divided into two paths, one path is sent into a reduction cavity (20) of the heating conversion furnace (1) through a fan (3) and a pipeline (9), and the other path is sent into a combustion chamber (21) of the heating conversion furnace (1) through a pipeline (10);

b.1) CO in the top gas fed into the reduction chamber (20)₂Reacting with the solid carbon carrier in the cavity, wherein the reaction formula is as follows:

the generated components are CO 80-92% and CO₂6-18% of a reducing gas comprising 2% of other constituent gases, which is fed to the reduction shaft furnace (2) through a duct (8) so as to form a gas circulation, the temperature inside said reduction chamber (20) being between 800 ℃ and 1000 ℃, and the temperature of the reducing gas fed from the reduction chamber (20) to the reduction shaft furnace (2) being between 570 ℃ and 900 ℃;

2) the furnace top tail gas sent into the combustion chamber (21) is mixed with oxygen-containing gas in the combustion chamber (21) and then is combusted, so as to provide heat energy for the reduction cavity (20);

c. before the whole system is started, firstly, CO is filled into the system through an inflation inlet (12) and an exhaust outlet (11)₂Gas or CO₂The mixed gas with CO replaces the air in the system, then the air charging port (12) and the exhaust port (11) are closed, the fan (3) is started, the heating combustion chamber (21) of the heating conversion furnace is ignited to rapidly heat the reduction cavity (20) to 800-1000 ℃, and the system is started and operates circularly;

d. whenthe system stops operating, the system is closed, and reducing gas in the system is discharged to ensure the safety of the system.

2. The process for producing sponge iron by the two-step reduction method according to claim 1, wherein the step a is: after being output, the furnace top tail gas output from the reduction shaft furnace (2) is washed by a washing device (4) and then divided into two paths, wherein one path is sent to a reduction cavity (20) of the heating conversion furnace (1) through a fan (3) and a pipeline (9), and the other path is sent to a combustion chamber (21) of the heating conversion furnace (1) through a pipeline (10).

3. The process for producing sponge iron by the two-step reduction method according to claim 2, wherein the step a is: after being output, the furnace top tail gas output from the reduction shaft furnace (2) is washed by a washing device (4) and then divided into two paths, one path is sent to a reduction cavity (20) of the heating conversion furnace (1) by a fan (3) and a pipeline (9), the other path is firstly sent to a gas storage cabinet (25), and after the gas storage cabinet (25) is filled with the furnace top gas, the furnace top gas is sent to a combustion chamber (21) of the heating conversion furnace by an output pipeline (10) of the gas storage cabinet (25).

4. The process for producing sponge iron by the two-step reduction method according to claim 1, 2 or 3, wherein the solid carbon carriers are coke and/or coal having a fixed carbon content of 80% or more; the iron oxide-containing ore is pellet ore and/or lump ore containing Fe of more than or equal to 64%.

5. A process for the production of sponge iron by atwo-step reduction process according to claim 1, 2 or 3, characterized in that the temperature in the reduction chamber (20) is 900 ℃, the temperature of the reducing gas fed into the reduction shaft furnace (2) is 850 ℃, and the composition of the reducing gas is CO 91%, CO₂7% and other component gases 2%; the components of the furnace top tail gas are CO 55% and CO₂43% and other component gases 2%; the top gas fed into the reduction chamber (20) accounts for 72-76% of the total top gas.

6. The process for producing sponge iron by the two-step reduction method according to claim 4, characterized in that the temperature in the reduction chamber (20) is 900 ℃ and the temperature of the reducing gas fed into the reduction shaft furnace (2) is 850 ℃, the reducing gas having the composition CO 91%, CO₂7% and other component gases 2%; the components of the furnace top tail gas are CO 55% and CO₂43% and other component gases 2%; the top gas fed into the reduction chamber (20) accounts for 72-76% of the total top gas.

7. The process for producing sponge iron by the two-step reduction method according to claim 3, wherein the gas pressure in the reduction chamber is 0.4MPa to 0.8MPa, and the gas pressure in the gas holder is 0.2MPa to 0.3 MPa.

8. A process for producing sponge iron by a two-step reduction method according to claim 3, wherein the step c: before the system is started for the first time, CO charged into the system is charged through the charging port (12) and the exhaust port (11)₂For industrial use of CO₂A gas; and c: CO in the gas storage tank (25) is used through the charging port (12) and the exhaust port (11)₂And the CO mixed gas is replaced by other gases in the system.

9. An apparatus for carrying out the process according to claim 1, comprising a reduction shaft furnace (2), the shaft furnace is provided with a reducing gas input port and a furnace top tail gas output port, and the shaft furnace can continuously feed and discharge materials in a closed state, it is characterized by also comprising a heating converter (1), wherein the heating converter (1) consists of a gas reduction chamber (20) and a heating part thereof, the heating part is provided with a flame heating combustion chamber (21), the gas reduction chamber (20) is positioned above the flame heating combustion chamber (21), the reduction cavity (20) is provided with an air inlet (24), an air outlet (23), a feed inlet (13) and a discharge outlet (14), the reduction cavity (20) can continuously feed and discharge materials in a closed state, and the combustion chamber (21) is provided with a furnace top tail gas input port (22), an oxygen-containing gas input port (15) and an exhaust gas discharge port (16); a furnace top tail gas output pipeline (26, 27) connected with a furnace top tail gas outlet of the reduction shaft furnace (2) is divided into two paths, one path is communicated with a reduction cavity (20) of the heating conversion furnace (1) through a fan (3) and a pipeline (9), the other path is communicated with a combustion chamber (21) of the heating conversion furnace (1) through a pipeline (10), and an external gas input port (12) and a system gas outlet (11) are connected to the pipeline (9); the gas outlet of the reduction cavity (20) is communicated with the reducing gas inlet of the reduction shaft furnace (2) through a pipeline (8).

10. The plant according to claim 9, characterized in that the furnace-top tail gas outlet conduit (26) is in communication with a washing device (4), the outlet conduit (27) of the washing device (4) beingdivided into two paths, one path being in communication with the reduction chamber (20) through the conduit (9) after passing through the fan (3), the other path being in communication with the inlet of a gas holder (25), the outlet of the gas holder (25) being in communication with the combustion chamber (21) through the conduit (10).