Short-process ironmaking flue gas ultra-low emission system of smelting reduction furnace

Abstract

The invention provides a short-process ironmaking flue gas ultra-low emission system of a smelting reduction furnace. The short-process ironmaking flue gas ultra-low emission system sequentially comprises a steady flow uniform distribution device, a first flue gas detection device, a three-phase self-balancing granulation coupling reactor for removing acid gas, a dust remover, a second flue gas detection device, a denitration reactor and a power device along a flue gas flowing path, a flue outlet of mixed flue gas composed of hot blast stove combustion flue gas, pea coal preparation drying kiln flue gas and mineral powder pre-reduction rotary kiln combustion flue gas is communicated with a steady flow uniform distribution device, and an outlet of the steady flow uniform distribution device is communicated with an inlet of the three-phase self-balancing granulation coupling reactor. The flue gas detection device is used for detecting the temperature, the flow, the humidity and the SO2 concentration of the mixed flue gas; a backflow flue is arranged between the outlet of the power device and the steady flow uniform distribution device, a backflow flue gas adjusting device is arranged in the backflow flue, and the backflow flue gas adjusting device is selectively started to adjust the temperature or / and the flow of the mixed flue gas according to the flue gas property detected by the flue gas detection device.

Description

Technical Field

[0001] The present invention relates to the field of flue gas treatment, and in particular to an ultra-low emission system for flue gas from a short-process ironmaking process in a smelting reduction furnace. Background Art

[0002] Smelting reduction furnace short-process ironmaking refers to a method of reducing iron ore in a high-temperature molten state without using a blast furnace. Smelting reduction is a type of ironmaking process that produces liquid iron without using a blast furnace. Its main energy source is non-coking coal. The smelting reduction ironmaking process is an important process route for non-blast furnace ironmaking and an important research and development direction for future ironmaking processes. It is a typical short-process ironmaking production process with the characteristics of low cost, low energy consumption, low carbon, and low emissions.

[0003] At present, in the short-process ironmaking process of the smelting reduction furnace, the flue gas generated from the three auxiliary machines of the smelting reduction furnace (combustion flue gas of the hot blast furnace, combustion flue gas of the drying kiln for preparing granular coal, combustion flue gas of the rotary kiln for pre-reduction of mineral powder) is also the main source of air pollution in the short-process ironmaking process of the smelting reduction furnace. The main components of the pollutants are SOx (including SO2 and SO3), NOx, dust and some heavy metals. These pollutants are discharged into the atmosphere with the flue gas, which will seriously affect the air quality and the living environment of human beings.

[0004] In the short-process ironmaking process of the smelting reduction furnace, the flue gas generated from the three auxiliary machines of the smelting reduction furnace (hot blast furnace combustion, granular coal preparation drying kiln combustion, ore powder pre-reduction rotary kiln combustion) has the characteristics of large operating fluctuations, specifically as follows: 1) Depending on the different S contents in the raw material pulverized coal and raw material ore, the SOx concentration fluctuates greatly; the SOx concentration is generally 500-7000 mg / Nm 3 ; 2) NOx concentration is generally 50-400 mg / Nm 3 , showing differential fluctuations; 3) The concentration of particulate matter in flue gas is generally 100-300 mg / Nm 3 (Average 150mg / Nm 3 ), the particle size distribution is very small, more than 90% of the flue gas are ultrafine particles with a particle size of 0-10μm, which are not easy to remove; 4) The flue gas temperatures of the three flue gases show differential changes, with a large fluctuation span, fluctuating in the range of 80℃ to 320℃; 5) The load fluctuation range is large, about 0% to 110%; 6) The moisture content of the flue gas is high, and the moisture content of the three flue gases fluctuates greatly, fluctuating from 8% to 35%, and the average moisture content of the three flue gases after mixing is about 15-18%; 7) The oxygen content of the three different flue gases varies greatly, and the average oxygen content of the three flue gases after mixing is about 5%.

[0005] The smelting reduction furnace short-process ironmaking device is in its starting stage. The main way to reduce the SOx and NOx concentrations in the flue gas of the smelting reduction furnace short-process ironmaking is to add desulfurization and denitrification devices. At present, the treatment route for flue gas desulfurization in the smelting reduction furnace short-process ironmaking process is to adopt the wet desulfurization process route.

[0006] There are sodium method, calcium method, ammonia method, double alkali method and other wet desulfurization methods, all of which have the disadvantages of high investment (reactors are basically required to be made of stainless steel or alloy steel) and operating costs, smoke tailing from chimneys, severe corrosion, high operating and maintenance costs, and the generation of secondary pollutants such as wastewater and waste slag. More importantly, the flue gas parameters (flue gas load, temperature and humidity) in the production process of the three auxiliary machines of the short-process ironmaking device of the smelting reduction furnace (hot blast furnace combustion, granular coal preparation drying kiln combustion, ore powder pre-reduction rotary kiln combustion) are different, with multiple load changes, and do not have good adaptability and poor operating reliability, resulting in the operation of the flue gas purification equipment and the host. The synchronization rate is low, which affects the normal production of the short-process ironmaking device of the smelting reduction furnace. In addition, the wet desulfurization cannot efficiently remove SO3 from the flue gas (the removal efficiency of wet desulfurization for SO3 is low, only about 20% to 50%. Therefore, it is necessary to seek a flue gas purification process with simple process flow, low investment and operating costs, which can carry out full flue gas treatment of various pollutants, and integrate desulfurization and dust removal. It is well adapted to the fluctuation of flue gas conditions in the production process of the three auxiliary machines of the short-process ironmaking device of the smelting reduction furnace (hot blast furnace combustion, granular coal preparation and drying kiln combustion, and ore powder pre-reduction rotary kiln combustion), and will not form secondary pollution. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide an ultra-low emission system for flue gas from a short-process ironmaking process of a smelting reduction furnace, which can well adapt to the fluctuations in flue gas conditions during the production process of the three major auxiliary machines of the short-process ironmaking device of the smelting reduction furnace (hot blast furnace combustion, granular coal preparation and drying kiln combustion, and ore powder pre-reduction rotary kiln combustion), and meet the stable ultra-low emission of multiple mixed flue gases generated by the three major auxiliary machines (hot blast furnace combustion, granular coal preparation and drying kiln combustion, and ore powder pre-reduction rotary kiln combustion) in the short-process ironmaking process of the smelting reduction furnace.

[0008] In order to solve the above technical problems, the present invention provides a smelting reduction furnace short-process ironmaking flue gas ultra-low emission system, which includes a flow stabilization and uniform distribution device, a first flue gas detection device, a three-phase self-balanced granulation coupling reactor for acid gas removal, a dust collector, a second flue gas detection device, a denitrification reactor and a power device in sequence along the flue gas flow path;

[0009] The flue outlet of the mixed flue gas composed of the hot blast furnace combustion flue gas, the granular coal preparation drying kiln flue gas, and the ore powder pre-reduction rotary kiln combustion flue gas is connected to the steady flow distribution device, and the outlet of the steady flow distribution device is connected to the inlet of the three-phase self-balancing granulation coupling reactor through the flue gas detection device. The first flue gas detection device detects the temperature, flow rate, humidity and SO2 concentration of the mixed flue gas;

[0010] The inlet of the dust collector is connected to the outlet of the three-phase self-balanced granulation coupling reactor, the outlet of the dust collector is connected to the inlet of the denitration reactor through the second flue gas detection device, the outlet of the denitration reactor is connected to the power unit, and the outlet of the power unit is also connected to the flue gas discharge port, and the second flue gas detection device detects the temperature, flow rate, humidity and SO2 concentration of the outlet mixed flue gas;

[0011] A return smoke duct is arranged between the outlet of the power unit and the flow stabilizing and evenly distributing device, and a return smoke regulating device is arranged in the return smoke duct. The return smoke regulating device selectively opens the return smoke regulating device according to the smoke properties detected by the first smoke detection device or the second smoke detection device to regulate the temperature and / or flow of the mixed smoke.

[0012] In some of the embodiments, the three-phase self-balanced granulation coupling reactor includes, from bottom to top, a gas-solid two-phase granulation premixing section, a Venturi jet acceleration section, a three-phase self-balanced granulation coupling section, and an acid-base neutralization reaction section.

[0013] In some of the embodiments, the gas-solid two-phase granulation premixing section is externally connected to a solid absorbent adding device, and the solid absorbent adding device is used to add the solid absorbent to the gas-solid two-phase granulation premixing section.

[0014] In some of the embodiments, the solid absorbent adding device includes a solid phase absorbent bin, a feeding control device, and a conveying device. The conveying device is located below the solid phase absorbent bin. The feeding control device controls the solid phase absorbent to fall into the conveying device. The outlet of the conveying device is connected to the gas-solid two-phase granulation premixing section.

[0015] In some of the embodiments, the conveying device is a chute with an inclination between 5° and 15°.

[0016] In some of the embodiments, hot air is blown toward the bottom of the chute under the chute.

[0017] In some embodiments, the three-phase self-balancing granulation coupling section is externally connected to a granulation coupling liquid phase generating device, and the granulation coupling liquid generating device is used to add liquid phase medium to the three-phase self-balancing granulation coupling section.

[0018] In some embodiments, the granulation-coupled liquid phase generating device includes a water tank for storing liquid phase medium, a pressurizing device, and a spray gun. The liquid phase medium in the water tank enters the spray gun for atomization under the action of the pressurizing device, and the spray gun is connected to the three-phase self-balancing granulation coupling section.

[0019] In some of the embodiments, a flow regulating device is further provided between the water tank and the spray gun, and the flow regulating device controls the amount of liquid medium added.

[0020] In some embodiments, the molar ratio of the added solid phase absorbent to S is about 1.2 to 1.8.

[0021] In some of the embodiments, it is characterized in that the reaction time of the mixed flue gas in the three-phase self-balanced granulation coupling reactor is 4-10S.

[0022] In some of the embodiments, the second flue gas detection device detects the flue gas properties at the outlet of the three-phase self-balancing granulation coupling reactor, and controls the amount of solid absorbent added to the solid absorbent adding device or the amount of liquid medium added to the granulation coupling liquid generating device according to the detected flue gas properties.

[0023] Compared with the prior art, the present invention adopts a three-phase self-balanced granulation coupling reactor to realize the three-phase self-balanced granulation coupling of gas, liquid and solid in the reactor, realizes the removal of acidic gases such as SO2, and the flue gas passes through the high-efficiency dust collector and deep denitrification reactor at the rear end to realize the removal of dust and NO X deep removal; at the same time, a flue gas detection device is arranged between the flow stabilizing and uniform distribution device and the three-phase self-balancing granulation coupling reactor, and the reflux flue gas regulating device is selectively opened according to the flue gas properties detected by the flue gas detection device to adjust the temperature and / or flow rate of the mixed flue gas, which is well adapted to the fluctuation of flue gas conditions in the production process of the three major auxiliary machines (hot blast furnace combustion, pulverized coal drying kiln combustion, and rotary kiln combustion) of the smelting reduction furnace short-process ironmaking device. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the overall flow chart of the ultra-low flue gas emission system of the present invention;

[0025] Figure 2 It is a schematic diagram of a flow chart of a three-phase self-balancing granulation coupling generator of the present invention;

[0026] Figure 3 It is a schematic diagram of the connection between the solid phase absorbent adding device and the three-phase self-balanced granulation coupling generator;

[0027] Figure 4 It is a schematic diagram of the connection between the granulation coupling liquid phase generating device and the three-phase self-balancing granulation coupling generator. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0029] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the terms "installed", "provided with", "mounted / connected", "connected", etc. should be understood in a broad sense. For example, "connection" can be a wall-mounted connection, a detachable connection, or an integral connection. It can be a mechanical connection or an electrical connection. It can be a direct connection or an indirect connection through an intermediate medium. It can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] Reference Figure 1-4 This embodiment provides a smelting reduction furnace short-process ironmaking flue gas ultra-low emission system, which includes a flow stabilization and uniform distribution device 5, a first flue gas detection device 6, a three-phase self-balanced granulation coupling reactor for acid gas removal, a dust collector 7, a second flue gas detection device 8, a denitrification reactor 9 and a power device 10 in sequence along the flue gas flow path;

[0032] The flue outlet of the mixed flue gas composed of the hot blast furnace combustion flue gas, the granular coal preparation drying kiln flue gas, and the ore powder pre-reduction rotary kiln combustion flue gas is connected to the steady flow distribution device 5, and the outlet of the steady flow distribution device 5 is connected to the inlet of the three-phase self-balancing granulation coupling reactor through the first flue gas detection device 6. The first flue gas detection device 6 detects the temperature, flow rate, humidity and SO2 concentration of the mixed flue gas;

[0033] The inlet of the dust collector 7 is connected to the outlet of the three-phase self-balancing granulation coupling reactor, and the outlet of the dust collector 7 is connected to the inlet of the denitrification reactor 9 through the second flue gas detection device 8. The outlet of the denitrification reactor 9 is also connected to the power unit 10, and the outlet of the power unit 10 is also connected to the flue gas discharge port. The second flue gas detection device 8 detects the temperature, flow rate, humidity and SO2 concentration of the outlet mixed flue gas.

[0034] A return flue is provided between the outlet of the power device 10 and the flow stabilizing and evenly distributing device 5, and a return flue gas regulating device 13 is provided in the return flue. The return flue gas regulating device 13 is selectively opened according to the properties of the flue gas detected by the first flue gas detection device 6 or the second flue gas detection device 8 to regulate the temperature and / or flow rate of the mixed flue gas;

[0035] More specifically, the three-phase self-balancing granulation coupling reactor includes, from bottom to top, a gas-solid two-phase granulation premixing section 1, a venturi jet acceleration section 2, a three-phase self-balancing granulation coupling section 3, and an acid-base neutralization secondary reaction section 4; the gas-solid two-phase granulation premixing section 1 is externally connected to a solid absorbent adding device 11, and the solid absorbent adding device 11 is used to add solid absorbent to the gas-solid two-phase granulation premixing section 1; the three-phase self-balancing granulation coupling section 3 is externally connected to a granulation coupling liquid phase generating device, and the granulation coupling liquid generating device is used to add liquid phase medium to the three-phase self-balancing granulation coupling section 3. The second flue gas detection device 8 detects the flue gas properties (flue gas flow, temperature, humidity, SO2 concentration, etc.) at the outlet of the three-phase self-balancing granulation coupling reactor, and controls the amount of solid absorbent added to the solid absorbent adding device 11 or the amount of liquid phase medium added to the granulation coupling liquid generating device 12 according to the detected flue gas properties.

[0036] Among them, Figure 3 As shown, the solid absorbent adding device 11 includes a solid phase absorbent bin 111, a feeding control device 112, and a conveying device formed by a chute 113; the chute 113 is located below the solid phase absorbent bin 111, and the feeding control device 112 controls the solid phase absorbent to fall into the chute 113, and the outlet of the conveying chute 113 is connected to the gas-solid two-phase granulation premixing section 1. Through the chute 113, under the gravity of the solid phase absorbent and the suction of the flue gas negative pressure in the reactor, there is no need to add a power source, and the addition can be freely adjusted under the regulation and control of the feeding control device 112 according to the system's demand for solid phase absorbent. The chute 113 is a square structure, and the inclination angle of the chute 113 can be freely adjusted according to the needs of the project, generally 5 to 15 degrees. Below the chute 113, hot air with a temperature higher than the flue gas dew point is also arranged to blow to the bottom of the chute 113, and the hot air can be provided by a centrifugal fan, a roots blower or other clean hot air source.

[0037] like Figure 4 As shown, the granulation coupling liquid phase generating device 12 includes a water tank 121 for storing liquid phase medium, a pressurizing device 123 (such as a high-pressure water pump) for conveying liquid phase medium, a spray gun, and a flow regulating device 122 between the water tank 121 and the spray gun. The liquid phase medium can be domestic water, industrial water, or treated water with a chloride ion concentration within a certain range. The liquid phase medium in the water tank 121 enters the spray gun for atomization at a certain pressure under the action of the pressurizing device 123, and the spray gun is connected to the three-phase self-balancing granulation coupling section 3 so that the atomized liquid phase medium enters the three-phase self-balancing granulation coupling section 3 for three-phase granulation reaction. During the granulation reaction, due to the evaporation of the liquid, the heat in the flue gas is absorbed, and the flue gas temperature is synchronously reduced. The amount of liquid phase medium added is controlled by the flow regulating device 122 that feeds back the liquid phase medium according to the humidity after the three-phase granulation.

[0038] The multiple streams of flue gas with multiple load conditions and changes in the hot blast furnace combustion flue gas, the granular coal preparation drying kiln flue gas, and the ore powder pre-reduction rotary kiln combustion flue gas are evenly mixed by the steady flow distribution device 5 and first introduced into the gas-solid two-phase granulation premixing section 1. In addition to being used as the first gas-solid reaction site, the gas-solid two-phase granulation premixing section 1 is also used for adding solid-phase absorbent. The gas-solid two-phase granulation premixing section 1 is located at the bottom of the entire three-phase self-balancing granulation coupling reactor. The solid-phase absorbent added to this part includes fresh alkaline absorbent and alkaline absorbent collected by the high-efficiency dust collector 7 in the ash hopper and recycled back to the reaction device for secondary use. The molar ratio of the added solid-phase absorbent to S is about 1.2 to 1.8.

[0039] The alkaline absorbent flows by gravity through a chute with a certain inclination angle and filled with fluidizing air of a certain temperature and pressure (60-150°C, 5-20kpa) to the gas-solid two-phase granulation premixing section 1 of the three-phase self-balancing granulation coupling reactor. The residence time of the flue gas in this reaction section is about 1-3s, thereby achieving the removal of strong acid gases such as SO3, HCL and HF in the mixed flue gas.

[0040] The Venturi jet acceleration section 2 is a communicating vessel connecting the gas-solid two-phase granulation premixing section 1 and the three-phase self-balancing granulation coupling section 3. Its function is to realize the rapid lifting of the gas and solid two-phase mixture after the primary reaction in the reactor to form a jet, and to create a fluidized environment after the gas, liquid and solid three-phase self-balancing granulation coupling reaction. The flow rate of the gas-solid two-phase flue gas in the Venturi jet acceleration section 2 can reach 30m / s to 70m / s, and the operation flexibility is large.

[0041] The three-phase self-balanced granulation coupling section 3 is located above the gas-solid two-phase Venturi acceleration section. The liquid medium required for self-balanced granulation is sprayed into the three-phase self-balanced granulation coupling reactor through a water spray gun in this section. With the help of the high-concentration, high-turbulence solid-phase materials in the reactor and the high-temperature gas temperature generated by the three auxiliary machines (hot blast furnace combustion flue gas, granular coal preparation drying kiln combustion flue gas, and mineral powder pre-reduction rotary kiln combustion flue gas) in the short-process ironmaking process of the smelting reduction furnace, the liquid medium water is effectively and quickly evaporated. The three-phase self-balanced granulation of gas, liquid and solid is realized, and a gas film and a liquid film are formed to form an acid-base neutralization liquid-phase ionic acid-base neutralization chemical reaction environment that can be completed instantly.

[0042] Above the Venturi jet acceleration section 2 is the three-phase self-balanced granulation coupling section 3 and the acid-base neutralization secondary reaction section 4. The particles after the gas, liquid and solid three-phase self-balanced granulation are further subjected to deep acid-base neutralization reaction in this section, realizing the efficient removal of SO2 and part of NO in the three major auxiliary machines in the short-process ironmaking process of the smelting reduction furnace. X In addition, under the action of the three-phase self-balanced reaction mechanism, the submicron-level fine particles in the flue gas are continuously condensed, agglomerated and combined, and the particle size becomes larger and coarser. The submicron-level fine particles brought by the smelting reduction furnace flue gas become large particles, which are filtered and adsorbed by the rear-end dust collector 7 to achieve ultra-low dust emissions. In this embodiment, the dust collector 7 uses a bag dust collector. At the same time, as a simple alternative to this embodiment, a high-efficiency electric dust collector or other high-efficiency dust collector can also be used.

[0043] The outlet of the three-phase self-balanced granulation coupling reaction section is directly connected to the high-efficiency bag filter 7. The powder layer material on the filter bag also contains a certain amount of alkaline absorbent, which can further absorb and remove acidic substances such as SOx and NOx in the flue gas while removing the flue gas dust. A large amount of unreacted absorbent is returned from the lower end of the bag through a large-flow air chute to the gas-solid two-phase granulation premixing section 1 for reuse, and a small part of the by-products that have been completely reacted are discharged to the by-product storage bin. Finally, the coarse particles agglomerated and condensed in the flue gas are purified by the bag filter 7, and then deeply denitrated by the SCR device of the downstream denitration reactor 9, and finally discharged to the chimney through the induced draft fan of the power device 10. The overall pressure drop of the flue gas in the three-phase self-balanced granulation coupling reaction system is 1.2-2.2kpa, the flue gas residence reaction time is 4-10s, and the ratio of local alkaline absorbent to S reaches 40-80.

[0044] Furthermore, in order to ensure that the three-phase self-balancing granulation coupling reactor has good adaptability under various working conditions, the system is equipped with a smoke detection device to detect the temperature, humidity and flow rate of the mixed smoke. The outlet of the steady flow distribution device 5 is connected to the inlet of the three-phase self-balancing granulation coupling reactor through the smoke detection device. A return flue is arranged between the outlet of the power device 10 and the steady flow distribution device 5, and a return flue gas regulating device 13 is arranged in the return flue. The return flue gas regulating device 13 is selectively opened according to the smoke properties detected by the first smoke detection device 6 or the second smoke detection device 8 to adjust the temperature and / or flow rate of the mixed smoke.

[0045] The inlet of the three-phase self-balancing granulation coupling reactor is under negative pressure. Under the regulation of the return flue gas regulating device 13, the high-temperature clean flue gas after denitrification heating can be directly led back to the inlet of the three-phase self-balancing granulation coupling reactor by using the return flue, thereby ensuring the normal and stable operation of the three-phase self-balancing granulation coupling reactor under low load conditions.

[0046] Taking a steel plant with an annual output of 550,000 tons / year smelting reduction furnace project as an example, when the three auxiliary machines (hot blast furnace combustion flue gas, granular coal preparation drying kiln combustion flue gas, ore powder pre-reduction rotary kiln combustion flue gas) of the smelting reduction furnace short-process ironmaking process are in normal production and operation, the mixed flue gas generated has a wet-based flue gas volume of about 310,000 Nm3 / h, SO2: 500-7000 mg / Nm 3 , the flue gas temperature is 120-140℃, the flue gas moisture content is 15-18%, and the flue gas oxygen content is about 5%.

[0047] (1) During the normal production process of the smelting reduction furnace, the flue gas is evenly distributed and mixed, and the temperature of the mixed flue gas is 120-140°C, the moisture content of the flue gas is 15-18%, and the flue gas parameters are within the design range. There is no need to open the reflux flue gas adjustment device 13 set in the system. By adjusting the flow control device of the granulation coupling liquid phase generating device, the flue gas temperature (humidity) at the reactor outlet is controlled to be not less than 70°C, and the amount of solid phase absorbent added is adjusted according to the outlet SO2 concentration to achieve the effect of gas, liquid and solid three-phase self-balanced granulation coupling reaction, and the SO2 in the outlet flue gas is controlled at 20mg / m 3 After the flue gas passes through the high-efficiency dust collector 7 and deep denitrification reactor 9 at the rear end, the dust is reduced to less than 5 mg / m 3 and NO X Less than 30 mg / m 3 .

[0048] (2) When only the hot blast furnace is in normal operation among the three auxiliary machines (hot blast furnace combustion flue gas, granulated coal preparation drying kiln combustion flue gas, and mineral powder pre-reduction rotary kiln combustion flue gas) in the short-process ironmaking process of the smelting reduction furnace, and the granulated coal preparation drying kiln and the mineral powder pre-reduction rotary kiln are not in operation, the flue gas temperature generated by the hot blast furnace combustion is about 150-320°C, the average temperature is 250°C, the water content in the flue gas is about 8-10%, and the amount of flue gas entering the flue gas ultra-low emission system is only about half of that in the above-mentioned working condition (1). At this time, the flue gas ultra-low emission system will automatically turn on the return flue gas adjustment device 13 set in the system, and return the clean and hot flue gas after denitrification to compensate the original mixed flue gas (at this time, the return flue gas adjustment device 13 does not need to turn on the external heat source). After the flue gas compensation, the flue gas volume at the inlet of the three-phase self-balancing granulation coupling reactor reaches more than 70% of the designed flue gas volume, and the flue gas temperature fluctuates in the range of 120-240°C, so that the three-phase self-balancing granulation coupling reactor can operate safely and stably. By adjusting the flow regulating device of the granulation coupling liquid phase generating device, the temperature (humidity) of the flue gas at the reactor outlet is controlled to be not less than 70°C, and the amount of solid phase absorbent added is adjusted according to the outlet SO2 concentration to achieve the effect of gas, liquid and solid three-phase self-balanced granulation coupling reaction, and the SO2 in the outlet flue gas is controlled at 20mg / m 3 After the flue gas passes through the high-efficiency dust collector 7 and deep denitrification reactor 9 at the rear end, the dust is reduced to less than 5 mg / m 3 and NO X Less than 30 mg / m 3 .

[0049] (3) When only the hot blast furnace and the granular coal preparation and drying kiln are in normal operation among the three auxiliary machines (the hot blast furnace combustion flue gas, the granular coal preparation and drying kiln combustion flue gas, and the ore powder pre-reduction rotary kiln combustion flue gas) in the short-process ironmaking process of the smelting reduction furnace, and the granular coal preparation and drying kiln are in normal operation, and the ore powder pre-reduction rotary kiln is not in operation, the mixed flue gas generated by the combustion of the hot blast furnace and the granular coal preparation and drying kiln is at a low temperature of only 80-115°C, 105°C on average, with a water content of 15-18%, and the flue gas volume is only half of the above-mentioned working condition (1). At this time, the flue gas ultra-low emission system will automatically turn on the return flue gas regulating device 13 set in the system (when the flue gas temperature is higher than 100°C, the return flue gas regulating device 13 does not need to turn on the external heat source, and when the flue gas temperature is lower than 100°C, the return flue gas regulating device 13 needs to turn on the external heat source), and return the clean, hot flue gas after denitrification to compensate for the original mixed flue gas. After flue gas compensation, the flue gas volume at the inlet of the three-phase self-balancing granulation coupling reactor reaches more than 70% of the designed flue gas volume, and the flue gas temperature is higher than 100°C. By adjusting the flow rate of the granulation coupling liquid phase generating device back to the regulating device, the reactor outlet flue gas temperature (humidity) is controlled to be not less than 70°C. At the same time, due to the low inlet flue gas temperature and the small amount of liquid phase water added, the system automatically increases the opening of the solid phase absorbent addition device on the basis of the gas, liquid and solid three-phase self-balancing granulation coupling reaction, and increases the solid phase absorbent feed, so that the three-phase self-balancing granulation coupling reactor can operate safely and stably. Through the action of the gas, liquid and solid three-phase self-balancing granulation coupling reaction, the SO2 in the outlet flue gas is controlled at 20mg / m 3 After the flue gas passes through the high-efficiency dust collector 7 and deep denitrification reactor 9 at the rear end, the dust is reduced to less than 5 mg / m 3 and NO X Less than 30 mg / m 3 .

[0050] (4) When only the ore powder pre-reduction rotary kiln combustion is operating normally among the three auxiliary machines (hot blast furnace combustion flue gas, granulated coal preparation drying kiln combustion flue gas, and ore powder pre-reduction rotary kiln combustion flue gas) in the short-process ironmaking process of the smelting reduction furnace, while the hot blast furnace and granulated coal preparation drying kiln are not operating, the flue gas temperature generated by the ore powder pre-reduction rotary kiln combustion is about 180-250°C, the water content in the flue gas is about 16%-35%, and the amount of flue gas entering the flue gas ultra-low emission device is only about half of that in the above-mentioned working condition (1). At this time, the flue gas ultra-low emission device will automatically turn on the return flue gas adjustment device 13 set in the system (at this time, the return flue gas adjustment device 13 does not need to turn on the external heat source), and return the clean and hot flue gas after denitrification to compensate the original mixed flue gas. After the flue gas compensation, the flue gas volume at the inlet of the three-phase self-balancing granulation coupling reactor reaches more than 70% of the designed flue gas volume, and the flue gas temperature fluctuates in the range of 150-200°C, so that the three-phase self-balancing granulation coupling reactor can operate safely and stably. By adjusting the flow regulating device of the granulation coupling liquid phase generating device, the temperature (humidity) of the flue gas at the reactor outlet is controlled to be not less than 70°C, and the amount of solid phase absorbent added is adjusted according to the outlet SO2 concentration to achieve the effect of gas, liquid and solid three-phase self-balanced granulation coupling reaction, and the SO2 in the outlet flue gas is controlled at 20mg / m 3 After the flue gas passes through the high-efficiency dust collector 7 and deep denitrification reactor 9 at the rear end, the dust is reduced to less than 5 mg / m 3 and NO X Less than 30 mg / m 3 .

[0051] (5) When only the hot blast furnace combustion and the ore powder pre-reduction rotary kiln combustion of the three major auxiliary machines (hot blast furnace combustion flue gas, granular coal preparation drying kiln combustion flue gas, and mineral powder pre-reduction rotary kiln combustion flue gas) are operating normally, while the granular coal preparation drying kiln combustion is not operating. At this time, the hot blast furnace combustion and the ore powder pre-reduction rotary kiln combustion are about 150-250°C, with an average temperature of 200°C, and the moisture content in the flue gas is about 14%-18%. The flue gas ultra-low emission device can operate normally in terms of flue gas temperature and flue gas volume under this condition (the reflux flue gas regulating device 13 does not need to be turned on at this time). The system controls the reactor outlet flue gas temperature (humidity) to be not lower than 70°C by adjusting the flow regulating device of the granulation coupling liquid phase generating device, and adjusts the amount of solid phase absorbent added according to the outlet SO2 concentration to achieve the effect of self-balanced granulation coupling reaction of gas, liquid and solid, and realize the control of SO2 in the outlet flue gas at 20mg / m 3 After the flue gas passes through the high-efficiency dust collector 7 and deep denitrification reactor 9 at the rear end, the dust is reduced to less than 5 mg / m 3 and NO X Less than 30 mg / m 3 .

[0052] After the flue gas is treated by the emission system of this embodiment, under the regulation of the gas, liquid and solid three-phase self-balance, the pollutants such as acidic gas, heavy metals and dioxins are efficiently and synergistically removed, while avoiding the flue gas from being too wet. The byproduct desulfurization ash in the system will not be too wet, and there will be no condensation agglomeration and device corrosion affecting the stable operation of the system. The flue gas is filtered by the high-efficiency dust collector 7 to remove dust and achieve ultra-low emissions. Meet the chimney outlet particulate matter concentration <5mg / m 3 , SO2 concentration <20mg / m 3 , NO x Concentration <30 mg / m 3 ultra-low emission standards.

[0053] The external heat source of the return flue gas conditioning device 13 can be a hot air furnace burning coal gas to blow hot air, or high-temperature steam, or electric heating. The solid phase absorbent is a calcium-based absorbent mainly composed of CaO and Ca(OH)2. The absorbent quality is: CaO content ≥ 60%; particle size ≤ 1mm; T60 ≤ 4min.

[0054] The above is only a preferred specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any technician familiar with the technical field who uses this concept to make non-substantial changes to the present invention within the technical scope disclosed by the present invention shall be deemed to infringe the protection scope of the present invention.

Claims

1. A smelting reduction furnace short-process ironmaking flue gas ultra-low emission system, characterized in that: The flue gas flow path includes a flow stabilizing and uniform distribution device, a first flue gas detection device, a three-phase self-balanced granulation coupling reactor for removing acidic gas, a dust collector, a second flue gas detection device, a denitration reactor and a power device in sequence; The flue outlet of the mixed flue gas composed of the hot blast furnace combustion flue gas, the granular coal preparation drying kiln flue gas, and the ore powder pre-reduction rotary kiln combustion flue gas is connected to the steady flow distribution device, and the outlet of the steady flow distribution device is connected to the inlet of the three-phase self-balancing granulation coupling reactor through the flue gas detection device. The first flue gas detection device detects the temperature, flow rate, humidity and SO2 concentration of the mixed flue gas; The inlet of the dust collector is connected to the outlet of the three-phase self-balanced granulation coupling reactor, the outlet of the dust collector is connected to the inlet of the denitration reactor through the second flue gas detection device, the outlet of the denitration reactor is connected to the power unit, and the outlet of the power unit is also connected to the flue gas discharge port, and the second flue gas detection device detects the temperature, flow rate, humidity and SO2 concentration of the outlet mixed flue gas; A return smoke duct is arranged between the outlet of the power unit and the flow stabilizing and evenly distributing device, and a return smoke regulating device is arranged in the return smoke duct. The return smoke regulating device selectively opens the return smoke regulating device according to the smoke properties detected by the first smoke detection device or the second smoke detection device to regulate the temperature and / or flow of the mixed smoke.

2. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 1 is characterized in that: The three-phase self-balancing granulation coupling reactor comprises, from bottom to top, a gas-solid two-phase granulation premixing section, a Venturi jet acceleration section, a three-phase self-balancing granulation coupling section, and an acid-base neutralization reaction section.

3. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 2 is characterized in that: The gas-solid two-phase granulation premixing section is externally connected to a solid absorbent adding device, and the solid absorbent adding device is used to add the solid absorbent to the gas-solid two-phase granulation premixing section.

4. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 3 is characterized in that: The solid absorbent adding device includes a solid phase absorbent bin, a feeding control device, and a conveying device. The conveying device is located below the solid phase absorbent bin. The feeding control device controls the solid phase absorbent to fall into the conveying device. The outlet of the conveying device is connected to the gas-solid two-phase granulation premixing section.

5. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 4 is characterized in that: The conveying device is a chute with an inclination between 5° and 15°.

6. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 5, characterized in that: Hot air is arranged below the chute and blown toward the bottom of the chute.

7. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 2, characterized in that: The three-phase self-balancing granulation coupling section is externally connected to a granulation coupling liquid phase generating device, and the granulation coupling liquid generating device is used to add liquid phase medium to the three-phase self-balancing granulation coupling section.

8. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 7, characterized in that: The granulation coupling liquid phase generating device comprises a water tank storing liquid phase medium, a pressurizing device and a spray gun. The liquid phase medium in the water tank enters the spray gun for atomization under the action of the pressurizing device. The spray gun is connected to the three-phase self-balancing granulation coupling section.

9. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 8, characterized in that: A flow regulating device is also arranged between the water tank and the spray gun, and the flow regulating device controls the amount of liquid medium added.

10. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 2, characterized in that: The molar ratio of the added solid phase absorbent to S is 1.2 to 1.

8.

11. The ultra-low emission system for short-process ironmaking flue gas from a smelting reduction furnace according to any one of claims 1 to 10, characterized in that: The reaction time of the mixed flue gas in the three-phase self-balanced granulation coupling reactor is 4-10S.

12. The ultra-low emission system of short-process ironmaking flue gas from a smelting reduction furnace according to claim 2 or 7, characterized in that: The second flue gas detection device detects the flue gas properties at the outlet of the three-phase self-balancing granulation coupling reactor, and controls the amount of solid absorbent added to the solid absorbent adding device or the amount of liquid medium added to the granulation coupling liquid generating device according to the detected flue gas properties.

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