CN104046714B - A kind of reduction reaction shaft furnace waste heat recovery cyclic utilization system - Google Patents

Abstract

The invention relates to a reduction reaction shaft furnace waste heat recycling system, which comprises a shaft furnace, a reformer and a waste gas discharge device. The shaft furnace is provided with a first exhaust port and a reduction gas inlet, and the reformer is provided with a raw material gas inlet and a The outlet of the reducing gas, the exhaust port and the inlet of the raw material gas are sequentially connected with a first gas-water heat exchanger, a scrubber, a carbon dioxide absorption device and a first mixing chamber, and the first mixing chamber combines the raw material gas and the The exhaust gas is mixed and sent to the reformer; the reducing gas inlet is connected to the raw material gas inlet; the reformer is also provided with a first gas port and a second gas port, the first gas port is connected to the waste gas discharge device, and the combustion air inlet and The fuel gas inlets are all communicated with the reformer through the second gas port. The invention not only realizes the full utilization of waste heat in each part of the shaft furnace, but also recovers carbon monoxide and hydrogen that have not been fully burned or reduced, improves energy utilization, reduces energy consumption, reduces emissions, and has remarkable economic and social benefits.

Description

A Reduction Reaction Shaft Furnace Waste Heat Recovery and Recycling System

technical field

The invention relates to a shaft furnace ironmaking waste heat recovery and recycling system, which belongs to the field of ironmaking technical facilities and equipment, and is used for the waste heat recovery and utilization of the shaft furnace direct reduction iron process.

Background technique

The development of direct reduced iron production is one of the important links for my country to get rid of the shortage of coking coal resources, change the energy structure of steel production, improve the quality and quality of steel products, solve the shortage of scrap steel resources, realize the comprehensive utilization of resources, and adhere to the sustainable development of the steel industry. Compared with other direct reduction processes, gas-based shaft furnace direct reduction technology has become the mainstream direct reduction process in the world due to its advantages of fast reduction speed, stable product quality, high degree of automation, large single-machine production capacity, and low process energy consumption.

At present, the dominant gas-based shaft furnace process in the world is the MIDREX method, and the basic principle of the MIDREX method is gas-solid phase countercurrent heat exchange and reduction reaction. The iron ore is heated and reduced by the hot reducing gas as it descends in the Midland shaft furnace. The direct reduction process of shaft furnace is composed of shaft furnace, reducing gas reforming furnace (also known as gas furnace), furnace top gas and cooling gas purification, flue gas waste heat recovery and other parts. Its general working principle is as follows: fuel gas and auxiliary gas are passed into the reformer to burn to generate high temperature, and raw material gas is passed into the reformer to undergo cracking reaction to generate high-temperature carbon monoxide and hydrogen (about 900 degrees) and other reducing gases. The iron ore in the shaft furnace chamber is passed into the shaft furnace for reduction reaction. The reduced iron ore falls into the cooling chamber at the bottom of the shaft furnace. Mine is cooled.

The waste heat of the shaft furnace direct reduction process mainly comes from the flue gas, followed by solids such as Shanghai slag, and the heat carried by liquids such as cooling water. The heat carried away by the flue gas accounts for about 70% of the heat balance expenditure of the fuel furnace. Utilization of flue gas waste heat utilization is the focus.

At present, the comprehensive utilization rate of shaft furnace waste heat recovery is low. Some of the discharged high-temperature gas does not recycle its heat energy, and directly washes and absorbs carbon dioxide. On the one hand, it wastes heat energy, and on the other hand, it affects the separation and absorption of impurities such as carbon dioxide and coal ash; The gas is not completely burned or completely reduced, and is directly discharged as exhaust gas, which wastes fuel and pollutes the environment.

Contents of the invention

Aiming at many deficiencies in the current shaft furnace direct reduction reaction process and waste heat recovery equipment, such as low waste heat recovery efficiency and large heat energy waste, a new reduction reaction shaft furnace waste heat recovery and recycling system is proposed, which comprehensively and efficiently utilizes the shaft furnace exhaust High temperature reducing gas and waste heat of combustion gas.

The technical scheme of the reduction reaction shaft furnace waste heat recovery and recycling system of the present invention is: a reduction reaction shaft furnace waste heat recovery and recycling system, including a shaft furnace, a reformer and a waste gas discharge device, and the shaft furnace is equipped with a first An exhaust port and a reducing gas inlet, the reformer is provided with a raw material gas inlet and a reducing gas outlet, and a first gas-water heat exchanger and a scrubber are sequentially connected between the exhaust port and the raw material gas inlet , a carbon dioxide absorption device and a first mixing chamber, the first mixing chamber mixes the raw material gas and the exhaust gas in the shaft furnace and sends it to the reformer; the reducing gas inlet is connected to the raw material gas inlet; the conversion The furnace is also provided with a first gas port and a second gas port, the first gas port is connected to the exhaust gas discharge device, and the combustion air inlet and the fuel gas inlet are both communicated with the reformer through the second gas port.

Further, a first pressurizer is provided between the raw gas inlet and the first mixing chamber, a second pressurizer is provided on the connecting pipe between the first gas port and the exhaust gas discharge device, and the combustion air A third pressurizer is provided on the connecting pipe between the inlet and the second gas port, and a fourth pressurizer is provided on the connecting pipe between the fuel gas inlet and the second gas port.

In the above scheme, a first regenerative heat exchanger is connected between the first gas port and the exhaust gas discharge device, and a second regenerative heat exchanger is also provided between the first regenerative heat exchanger and the exhaust gas discharge device. A reversing valve; a second reversing valve and a second regenerative heat exchanger are sequentially arranged between the combustion air inlet and the second air port, the first reversing valve, the second reversing valve There is a pipeline communication between the valve and the exhaust gas discharge device; a third reversing valve is connected between the fuel gas inlet and the second gas port, and the third reversing valve, the first gas port and the There is a pipeline communication between the second gas ports.

In the above scheme, a fourth reversing valve is further provided between the carbon dioxide absorbing device and the first mixing chamber, and a second mixing chamber is connected between the fourth reversing valve and the fuel gas inlet, so The mixing chamber mixes the gas passing through the reversing valve with the fuel gas and sends it to the reformer.

Further, a fifth pressurizer is provided between the fourth reversing valve and the second mixing chamber.

In the above solution, the cooling cavity at the bottom of the shaft furnace is further provided with a second exhaust port; the gas discharged from the second exhaust port passes through the second gas-water heat exchanger and is re-transported to the cooling gas inlet.

Further, a sixth pressurizer is provided on the pipeline between the second air-water heat exchanger and the cooling air inlet.

The reduction reaction shaft furnace waste heat recovery and recycling system and method of the present invention are comprehensive and compact in structure, which not only realizes full utilization of waste heat in each part of the shaft furnace, but also recovers carbon monoxide and hydrogen that have not been fully burned or reduced, and at the same time through gas-water heat exchange The waste heat is recovered first, and then carbon dioxide and coal ash and other impurities are separated and absorbed through the scrubber and carbon dioxide absorption device. The working principle is simple and reliable, and the gas separation and purification and waste heat recovery and utilization efficiency are high. consumption, reduced emissions, and significant economic and social benefits.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Fig. 1 is a schematic diagram of Embodiment 1 of the present invention.

Fig. 2 is a schematic diagram of Embodiment 2 of the present invention.

Fig. 3 is a schematic diagram of Embodiment 3 of the present invention.

Fig. 4 is a schematic diagram of Embodiment 4 of the present invention.

In the figure: 1 shaft furnace; 1-1 first exhaust port; 1-2 reducing gas inlet; 1-3 cooling chamber; 1-4 second exhaust port; 2 reformer; 2-1 raw material gas inlet; 2 -2 reducing gas outlet; 2-3 first gas port; 2-4 second gas port; 3 tail gas discharge device; 4 first gas-water heat exchanger; 5 scrubber; 6 carbon dioxide absorption device; 7 first mixing chamber; 8 The first pressurizer; 9 the first regenerative heat exchanger; 10 the first reversing valve; 11 the second reversing valve; 12 the second regenerative heat exchanger; 13 the third reversing valve; 14 the fourth Reversing valve; 15 second mixing chamber; 16 second air-water heat exchanger; 17 second pressurizer; 18 third pressurizer; 19 fourth pressurizer; 20 fifth pressurizer; 21 sixth Pressurizer.

detailed description

Embodiment one

As shown in Figure 1, a reduction reaction shaft furnace waste heat recovery and recycling system includes a shaft furnace 1, a reformer 2 and a waste gas discharge device 3. The shaft furnace 1 is provided with a first exhaust port 1-1 and a reduction Gas inlet 1-2, the reformer 2 is provided with a raw material gas inlet 2-1 and a reducing gas outlet 2-2, and the exhaust port 1-1 and the raw material gas inlet 2-1 are sequentially connected with The first air-water heat exchanger 4, the scrubber 5, the carbon dioxide absorption device 6 and the first mixing chamber 7, a first pressurizer 8 is arranged between the feed gas inlet and the first mixing chamber 7, and is used for feeding the The raw material gas is pressurized, and the first mixing chamber 7 mixes the raw material gas and the exhaust gas in the shaft furnace 1 and sends it to the reformer 2; the reducing gas inlet 1-2 and the raw material gas inlet 2- 1 connected; the reformer 2 is also provided with a first gas port 2-3 and a second gas port 2-4, the first gas port 2-3 is connected with the waste gas discharge device 3, and the first gas port 2- 3 and the connecting pipe of the exhaust gas discharge device 3 is provided with a second pressurizer 17, which is used to pressurize the exhaust gas entering the exhaust gas discharge device 3, and the combustion-supporting air inlet and the fuel gas inlet both pass through the second gas port 2 -4 communicates with the reformer 2, wherein a third pressurizer 18 is provided on the connecting pipe between the combustion air inlet and the second gas port 2-4, which is used to pressurize the combustion air, the The connecting pipe between the fuel gas inlet and the second gas port 2-4 is provided with a fourth pressurizer 19 for pressurizing the fuel gas.

The working process of this embodiment is: the pressurized combustion-supporting air and fuel gas are sent into the reformer 2 through the second gas port 2-4 for combustion to generate high temperature, and the raw material gas is passed into the reformer 2 for cracking reaction to generate High-temperature carbon monoxide and hydrogen (about 900 degrees) and other reducing gases are passed into the shaft furnace to reduce the iron ore in the shaft furnace cavity, and the reduced iron ore falls into the cooling chamber 1 at the bottom of the shaft furnace In -3, the cooling gas that passes into from the bottom of the cooling chamber 1-3 cools the iron ore in the cooling chamber. Adopting the technical solution of this embodiment, utilizing the waste heat of the reducing gas (about 400 degrees) discharged from the top of the shaft furnace and the carbon monoxide and hydrogen in it, on the one hand, the heat of the reducing gas is exchanged to normal temperature through the first gas-water heat exchanger 4 water to form new available water vapor energy; on the other hand, the reducing gas after passing through the first air-water heat exchanger 4 passes through the scrubber 5 and the carbon dioxide absorption device 6 to realize the reduction of the carbon dioxide contained in the reducing gas. Separating and absorbing impurities such as coal ash to obtain carbon monoxide and hydrogen with a high content rate, and then mixing with the raw material gas in the first mixing chamber 7 and then passing it into the reformer 2, so as to further enter the A chemical reaction takes place in the shaft furnace 1 .

Embodiment two

As shown in Fig. 2, this embodiment is based on the technical solution of the first embodiment, and the following technical solution is added: a first accumulator is connected between the first gas port 2-3 and the exhaust gas discharge device 3 A thermal heat exchanger 9, a first reversing valve 10 is also provided between the first regenerative heat exchanger 9 and the exhaust gas discharge device 3; the combustion air inlet and the second air port 2- 4, a second reversing valve 11 and a second regenerative heat exchanger 12 are provided in sequence, and there is a The pipeline is connected; the third reversing valve 13 is connected between the fuel gas inlet and the second gas port 2-4, and the third reversing valve 13, the first gas port 2-3 and the There is pipeline communication between the second air ports 2-4.

The working process of this embodiment is: the pressurized combustion-supporting air and fuel gas are sent into the reformer 2 through the second gas port 2-4 for combustion to generate high temperature, and the raw material gas is passed into the reformer 2 for cracking reaction to generate High-temperature carbon monoxide and hydrogen (about 900 degrees) and other reducing gases are passed into the shaft furnace to reduce the iron ore in the shaft furnace cavity, and the reduced iron ore falls into the cooling chamber 1 at the bottom of the shaft furnace In -3, the cooling gas that passes into from the bottom of the cooling chamber 1-3 cools the iron ore in the cooling chamber. By adopting the technical solution of this embodiment, the preheating of the combustion-supporting air can be realized, and the rate at which the combustion-supporting air enters the reformer 2 for chemical reaction with the fuel gas can be increased. The fuel gas is pressed into the right chamber of the reformer through the third reversing valve 13, and at the same time, the combustion-supporting air pressurized by the third pressurizer 18 enters the second regenerative heat exchanger 12 through the second reversing valve 11. A certain amount of heat has been stored in the second regenerative heat exchanger 12 in advance. This heat can preheat the combustion-supporting air to increase its temperature, and then the high-temperature combustion-supporting air is also pressed into the right chamber of the reformer. Due to the high temperature, Fuel gas and combustion-supporting air are burned in the right chamber of the reformer, and the temperature in the reformer rises rapidly, so that the raw material gas passed into the reformer 2 undergoes cracking reaction to generate high-temperature reducing gas, which is used for the reduction reaction of the shaft furnace; at the same time, after combustion The high-temperature tail gas in the reformer is discharged into the first regenerative heat exchanger 9 through the first gas port 2-3 of the left chamber of the reformer along the pipeline, and the high-temperature tail gas is exchanged through heat, leaving most of the heat in the first heat After the type heat exchanger 9, the low-temperature waste gas is pressurized by the first reversing valve 10 and the second pressurizer 17, and then the low-temperature waste gas is discharged into the atmosphere through the tail gas discharge device 3 . At this time, the second regenerative heat exchanger 12 releases heat, and the first regenerative heat exchanger 9 stores heat.

After a large amount of heat is stored in the first regenerative heat exchanger 9, the fuel pressure is injected into the left chamber of the reformer by adjusting the third reversing valve 13; at the same time, by adjusting the first reversing valve 10 and the second reversing valve 11. Send the combustion-supporting air into the first regenerative heat exchanger 9 through the first reversing valve 10. Since a large amount of heat has been stored in the first regenerative heat exchanger 9, the heat can preheat the combustion-supporting air to make it Raise the temperature, and then enter the left chamber of the reformer. Due to the high temperature, the fuel and combustion air burn in the left chamber of the reformer, and the temperature in the reformer rises rapidly; at the same time, the high-temperature exhaust gas in the furnace passes through the right chamber of the reformer Entering the second regenerative heat exchanger 12, the high-temperature exhaust gas passes through heat exchange, leaving most of the heat behind the second regenerative heat exchanger 12, and the low-temperature exhaust gas passes through the second reversing valve 11, and passes through the second pressurizer After 17 is pressurized, the low-temperature waste gas is discharged into the atmosphere through the tail gas discharge device 3 . At this time, the second regenerative heat exchanger 12 stores heat, and the first regenerative heat exchanger 9 releases heat. , the second regenerative heat exchanger 12 and the first regenerative heat exchanger 9 work alternately and cyclically in sequence, so as to achieve the effect of self-utilization of high-temperature combustion tail gas waste heat in the reformer 2 .

Embodiment three

As shown in Figure 3, this embodiment is based on the technical solution of the second embodiment, and the following technical solution is added: a fourth commutation is also provided between the carbon dioxide absorption device 6 and the first mixing chamber 7 valve 14, a second mixing chamber 15 is connected between the fourth reversing valve 14 and the fuel gas inlet, and a fifth adding chamber 15 is arranged between the fourth reversing valve 14 and the second mixing chamber 15. The press 20 , the mixing chamber 15 mixes the gas passing through the reversing valve 14 and the fuel gas and then sends it to the reformer 2 .

The working process of this embodiment is: the pressurized combustion-supporting air and fuel gas are sent into the reformer 2 through the second gas port 2-4 for combustion to generate high temperature, and the raw material gas is passed into the reformer 2 for cracking reaction to generate High-temperature carbon monoxide and hydrogen (about 900 degrees) and other reducing gases are passed into the shaft furnace to reduce the iron ore in the shaft furnace cavity, and the reduced iron ore falls into the cooling chamber 1 at the bottom of the shaft furnace In -3, the cooling gas that passes into from the bottom of the cooling chamber 1-3 cools the iron ore in the cooling chamber. By adopting the technical solution of this embodiment, the fuel gas can be updated and supplemented online in a timely manner during the shaft furnace reaction process. The specific implementation process is as follows: first, the reducing gas discharged from the reformer 2 enters the shaft furnace through the reducing gas inlet 1-2 2, after 6 hours of reduction reaction, it is discharged from the first exhaust port 1-1 of the shaft furnace, and the temperature of the discharged top gas is normally about 400 degrees; the top gas enters the first gas-water heat exchanger 4 , there is a heat exchange tube in the first air-water heat exchanger 4, and the cold water at normal temperature enters from one end of the heat exchange tube and is discharged from the other end. The normal-temperature cold water in the exchange tube is gradually turned into water vapor, which is discharged from the other end of the heat exchange tube, and the discharged high-temperature water vapor can be further utilized; the furnace top gas cooled by the first gas-water heat exchanger 4 enters the scrubber 5 Wash off impurities such as dust, and then enter the carbon dioxide absorption device 6 to further filter out the carbon dioxide contained in the furnace top gas, and the remaining high-content carbon monoxide and hydrogen gas pass through the fourth reversing valve 14 and pass through the fifth pressurized Pressurized by the pressurizer 20, it enters the second mixing chamber 15, mixes and supplements with the fuel gas pressurized by the fourth pressurizer 19, and transports it to the reformer 2 to participate in the combustion reaction. It is worth noting that in this embodiment, the reversing valve 14 can be adjusted as required to realize the splitting of the remaining high-content carbon monoxide and hydrogen after passing through the carbon dioxide absorbing device 6, one way flows to the second mixing chamber 15, and the other way flows to the first mixing chamber 15. The mixing chamber 7 mixes with the raw material gas and enters the reformer 2 for recycling.

Embodiment four

As shown in Figure 4, this embodiment is based on the technical solution of the third embodiment, and the following technical solution is added: the cooling cavity 1-3 at the bottom of the shaft furnace 1 is also provided with a second exhaust port 1- 4. The gas discharged from the second exhaust port 1-4 passes through the second air-water heat exchanger 16 and is re-delivered to the cooling air inlet, wherein the connection between the second air-water heat exchanger 16 and the cooling air inlet A sixth pressurizer 21 is provided on the pipeline between them.

The working process of this embodiment is: the pressurized combustion-supporting air and fuel gas are sent into the reformer 2 through the second gas port 2-4 for combustion to generate high temperature, and the raw material gas is passed into the reformer 2 for cracking reaction to generate High-temperature carbon monoxide and hydrogen (about 900 degrees) and other reducing gases are passed into the shaft furnace to reduce the iron ore in the shaft furnace cavity, and the reduced iron ore falls into the cooling chamber 1 at the bottom of the shaft furnace In -3, the cooling gas that passes into from the bottom of the cooling chamber 1-3 cools the iron ore in the cooling chamber. By adopting the technical solution of this embodiment, the cooling gas at the bottom of the cooling chamber 1-3 can be replenished during the shaft furnace reaction process. The specific realization process is: firstly, the cooling gas pressurized by the presser is pressed into the cooling chamber 1-3. 3, after 3-5 hours of cooling, the cooling gas temperature rises to about 450 degrees; the medium-temperature gas discharged from the second exhaust port 1-4 enters the second air-water heat exchanger 16, and the second air-water There is a heat exchange tube in the heat exchanger 16, and cold water at normal temperature enters from one end of the heat exchange tube; through the internal heat exchange of the second air-water heat exchanger 16, the heat is transferred to the cold water at normal temperature in the heat exchange tube, so that it gradually becomes water The steam is discharged from the other end of the heat exchange tube, and the high-temperature water vapor is discharged, which can be further utilized. The cooling gas discharged from the second air-water heat exchanger 16 is pressurized by the sixth pressurizer 21 and replenished into the cooling chamber 1-3 Recycling is realized in the cooling gas at the bottom.

Claims (6)

1. a reduction reaction shaft furnace waste heat recovery cyclic utilization system, comprise shaft furnace (1), converter (2) and exhaust emission device (3), it is characterized in that, described shaft furnace (1) is provided with first row gas port (1-1) and reducing gas import (1-2), described converter (2) is provided with raw material gas inlet (2-1) and reducing gas outlet (2-2), the first air-water heat exchanger (4) is connected with in turn between described venting port (1-1) and described raw material gas inlet (2-1), washer (5), absorption unit of dioxide carbon (6) and the first mixing section (7), described first mixing section (7) will be sent in converter (2) after the exhaust mixing in unstripped gas and shaft furnace (1), described reducing gas import (1-2) is connected with described raw material gas inlet (2-1), described converter (2) is also provided with the first gas port (2-3) and the second gas port (2-4), described first gas port (2-3) is connected with described exhaust emission device (3), and combustion air inlet and fuel gas inlet are all communicated with described converter (2) by described second gas port (2-4), be connected with the first heat regenerator (9) between described first gas port (2-3) and described exhaust emission device (3), between described first heat regenerator (9) and described exhaust emission device (3), be also provided with the first reversing valve (10), be provided with the second reversing valve (11) and the second heat regenerator (12) between described combustion air inlet and described second gas port (2-4) successively, described first reversing valve (10), between described second reversing valve (11) and described exhaust emission device (3), have pipeline communication, be connected with the 3rd reversing valve (13) between described fuel gas inlet and described second gas port (2-4), described 3rd reversing valve (13), between described first gas port (2-3) and described second gas port (2-4), have pipeline communication.

2. a kind of reduction reaction shaft furnace waste heat recovery cyclic utilization system according to claim 1, it is characterized in that, the first press (8) is provided with between raw material gas inlet and described first mixing section (7), the connecting tube of described first gas port (2-3) and described exhaust emission device (3) is provided with the second press (17), the connecting tube of described combustion air inlet and described second gas port (2-4) is provided with the 3rd press (18), and the connecting tube of described fuel gas inlet and described second gas port (2-4) is provided with the 4th press (19).

3. a kind of reduction reaction shaft furnace waste heat recovery cyclic utilization system according to claim 1, it is characterized in that, the 4th reversing valve (14) is also provided with between described absorption unit of dioxide carbon (6) and described first mixing section (7), be connected with the second mixing section (15) between described 4th reversing valve (14) and described fuel gas inlet, described mixing section (15) is sent in converter (2) after being mixed by the gas of described reversing valve (14) and described fuel gas.

4. a kind of reduction reaction shaft furnace waste heat recovery cyclic utilization system according to claim 3, is characterized in that, is provided with slender acanthopanax press (20) between described 4th reversing valve (14) and described second mixing section (15).

5. a kind of reduction reaction shaft furnace waste heat recovery cyclic utilization system according to claim 1, is characterized in that, the cooling chamber (1-3) of described shaft furnace (1) bottom also has second exhaust port (1-4); Described second exhaust port (1-4) expellant gas flows to cold gas import again by after the second air-water heat exchanger (16).

6. a kind of reduction reaction shaft furnace waste heat recovery cyclic utilization system according to claim 5, it is characterized in that, the pipeline between described second air-water heat exchanger (16) and described cold gas import is provided with the 6th press (21).