CN112569759B - Sintering process based on coupling of flue gas pollutant emission reduction through sintering flue gas quality-divided circulation - Google Patents
Sintering process based on coupling of flue gas pollutant emission reduction through sintering flue gas quality-divided circulation Download PDFInfo
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Abstract
The invention relates to a sintering process for emission reduction of flue gas pollutants based on mass-distribution cycle coupling of sintering flue gas, which adopts the technical scheme that the sintering process comprises a sintering machine trolley, sintering airflow, flue gas formed after combustion-supporting sintering, a sintering mixture and sintered ore formed after sintering; the sintering machine is divided into an ignition area, a low-temperature flue gas area and an SO area along the traveling direction of the trolley in sequence 2 Region of rapid rise in concentration, SO 2 The concentration is rapidly reduced in the area and the high-temperature flue gas area, and the sintering flue gas passes through the low-temperature flue gas main flue and the high-SO flue gas main flue respectively 2 Collecting a main flue gas flue and a main flue gas flue for high-temperature flue gas, desulfurizing the sintering flue gas in the main flue gas flue for low-temperature flue gas by spraying excessive ammonia water, and then feeding the desulfurized sintering flue gas into a sinter cooling furnace for denitration, wherein the high SO content is 2 The sintering flue gas of the flue gas main flue and oxygen are mixed and then enter a high-temperature flue gas circulation cover above a sintering material layer in a low-temperature flue gas area, and enter the sintering material layer again to participate in sintering as combustion-supporting air under the suction action of a fan. The invention has simple process, low investment and low operation cost.
Description
Technical Field
The invention relates to an industrial flue gas purification process in the field of environmental protection, in particular to a sintering process based on mass-divided circulation coupling of sintering flue gas and flue gas pollutant emission reduction.
Background
With the continuous improvement of the national requirements on environmental protection in recent years, the sintering flue gas of domestic iron and steel enterprises is subjected to desulfurization and denitrification treatment.
The flue gas desulfurization techniques can be divided into dry and wet desulfurization techniques, the dry technique mainly refers to a circulating fluidized bed technique, and the wet technique mainly includes a limestone/lime-gypsum method, an ammonia-ammonium sulfate method, a double subtraction method and a seawater desulfurization technique. The sintering flue gas has the characteristic of large fluctuation of the flue gas quantity, and the circulating fluidized bed technology has the technical risk of bed collapse; the ammonia-ammonium sulfate method has high desulfurization efficiency, but has the problems of secondary pollution such as easy generation of aerosol, ammonia escape and the like, strong corrosivity, difficult crystallization of ammonium sulfate and the like due to the characteristics of the process; the double alkali method belongs to a elimination process because the desulfurizer is difficult to regenerate and is easy to generate high-salinity wastewater; the seawater desulfurization technology has regional limitation; the limestone/lime-gypsum method can adapt to the characteristics of complex working conditions of the sintering machine, large flue gas amount, low temperature, large change, complex flue gas components, high oxygen content and the like, and has the advantages of rich limestone resources and better quality, so the limestone-gypsum method has natural advantages, is widely applied to flue gas desulfurization projects of the sintering machine and is stable in operation.
In the aspect of denitration technology, the SCR or SNCR technology is mature and widely applied at present and is stable in operation. However, because the temperature of the sintering flue gas in the iron and steel plant is low (<200 ℃), the flue gas amount is large, the change is large, and the like, the SCR technology (the optimal reaction temperature is 320-20 ℃) or the SNCR technology (the optimal reaction temperature is 800-1200 ℃) which are commonly used for flue gas denitration of a coal-fired boiler is difficult to directly adopt, and the denitration method needs to be applied to the sintering flue gas denitration of the iron and steel plant after process optimization and technical innovation. At present, two schemes exist at home and abroad. The first scheme comprises the following steps: and (3) adopting a low-temperature catalyst, and directly introducing sintering flue gas into an SCR reactor for catalytic denitration after rectification, ammonia injection and mixing. The method has the advantages of no need of heating flue gas, simple process route, immature low-temperature catalyst technology at present in China, high unit price of the catalyst, high consumption, large initial investment and low denitration efficiency. Scheme II: the method is characterized in that a medium-temperature catalyst is adopted, sintering flue gas is preheated by an air preheater and heated by a flue burner before entering a denitration reactor, the temperature of the flue gas is increased to an optimal reaction temperature range (320-. The medium-temperature catalyst has the advantages of mature and wide domestic application, high denitration efficiency, low unit price, low catalyst consumption and low initial investment, and has the defects of adding an afterburner, providing fuel and considering the influence of occupied land. Based on the serious defects of the first scheme and the second scheme, in recent years, domestic scholars develop the medium-low temperature SCR denitration catalyst, and the optimal reaction temperature range of the catalyst is (220-.
Although the technology of the sintering flue gas desulfurization and denitration process is mature, the flue gas purification process is long in route and high in treatment cost due to the fact that the sintering flue gas desulfurization and denitration processes are connected in series when the sintering flue gas desulfurization and denitration process is applied to engineering. In view of the above, in recent years, various integrated technologies of desulfurization and denitrification, such as ammonia desulfurization synchronous complexation absorption denitrification technology, activated carbon (coke) adsorption desulfurization denitrification technology, advanced oxidation-absorption desulfurization denitrification technology, etc., have been developed through technical introduction, digestion and improvement in China.
(1) The ammonia desulfurization synchronous complexing absorption denitration technology is developed by Wuhan iron and steel (group) companies and Wuhan science and technology universities together, and the principle is that a complexing agent is added into an ammonia water absorption liquid, so that NOx in smoke is complexed and absorbed while sulfur dioxide in the smoke is absorbed by absorption liquid. The technology is subjected to field test in a Wu-Steel five-sintering workshop, and the denitration efficiency reaches 60%. However, the technology cannot be effectively popularized and applied due to the problems of high regeneration and recycling cost of the complexing agent, aerosol existing in ammonia desulphurization and the like.
(2) The activated coke adsorption method earliest by German BDeveloped by ergbau-Forschung corporation. The active coke of the adsorbent slowly moves from top to bottom in the adsorption tower of the moving bed, the flue gas passes through the moving bed layer in a cross flow mode, and SO in the flue gas 2 Is adsorbed and reacts with O 2 Formation of SO 3 And further with H in the adsorbed state 2 The sulfuric acid generated by the O reaction is stored in the micropores of the adsorbent. NOx and SO 2 There is competitive adsorption when SO 2 When the adsorption is complete, the active coke begins to denitrate, at this time, ammonia can be introduced into the tower, and the ammonia and the adsorbed NOx react to generate nitrogen, and then the nitrogen is discharged along with the purified flue gas. Discharging the adsorbent saturated in adsorption through a discharger, sending the adsorbent to a regeneration tower, and regenerating for cyclic use to obtain high-concentration SO 2 The gas can be further converted into liquid SO 2 Or H 2 SO 4 . The first sintering flue gas active coke adsorption desulfurization and denitrification process introduced in China is applied to Tai-Gao steel in a cross flow mode, so that the denitrification efficiency is lower by about 40%. Through recent improvement, the existing sintering flue gas active coke adsorption desulfurization and denitrification process is applied to a plurality of steel mills in China. But the investment is large, the operation cost is high, and the safety and the stability of the operation are difficult to ensure.
No matter the technology is an independent desulfurization or denitration technology or a desulfurization and denitration integrated technology, the technical aim is to treat the tail end of the sintering flue gas, so that the investment of desulfurization and denitration is large and the operation cost is high due to the characteristics of the technology. To effectively reduce the investment and the operation cost, the pollution emission reduction must be carried out from the source and the sintering process.
Disclosure of Invention
Aiming at a series of problems of large investment, high operation cost, difficult treatment of waste catalyst and the like of the existing sintering flue gas desulfurization and denitrification, the invention provides the sintering process based on the mass-cycle coupling flue gas pollutant emission reduction of the sintering flue gas, which has the advantages of simple process scheme, no need of purchasing catalyst, energy conservation, consumption reduction, small occupied area and low investment and operation cost of flue gas denitrification equipment.
The process comprises a sintering machine and a trolley thereof, sintering airflow, sintering flue gas formed after combustion-supporting sintering, sintering mixture and sintered ore formed after sintering; the sintering airflow enters the sintering mixture under the suction action of the fanThe material layer is used for supporting combustion and sintering to form sintering flue gas, and the sintering flue gas passes through a sintering mixed material layer, a trolley grate of the sintering machine and an air box below the trolley and enters a main flue; sintering the sintering mixture at a high temperature under the combustion supporting of sintering airflow to form sinter, and discharging the sinter into a sinter cooling furnace along with a trolley at a fixed bend at the tail of the sintering machine; dividing the sintering machine into an ignition area, a low-temperature flue gas area and an SO area along the traveling direction of a trolley of the sintering machine 2 Region of rapid rise in concentration, SO 2 5 areas such as a concentration rapid reduction area and a high-temperature flue gas area; the sintering flue gas passes through the low-temperature flue gas main flue and the high SO flue respectively 2 The main flue gas flue and the main flue gas flue for high-temperature flue gas are collected, and the main flue gas flue for low-temperature flue gas is used for collecting sintering flue gas in an ignition area ， And the low-temperature flue gas area is adjacent to the low-temperature sintering flue gas in the length range of 70-80% of the ignition area, and the high SO 2 Collecting SO from flue gas main flue 2 Region of rapidly decreasing concentration and SO 2 Sintering flue gas in a region with rapidly increased concentration and a region with low temperature flue gas close to SO 2 And the low-temperature sintering flue gas in the length range of 20-30% of the concentration rapid rise region, and the high-temperature flue gas main flue collects the high-temperature sintering flue gas in the high-temperature flue gas region.
The sintering flue gas in the low-temperature flue gas main flue is desulfurized by spraying excessive ammonia water and then is introduced into the low-temperature flue gas circulating cover through the low-temperature flue gas pipeline; said high SO 2 The sintering flue gas in the flue gas main flue is mixed with oxygen and then is subjected to high SO 2 High SO above sinter bed entering low-temperature flue gas area through circulating flue gas pipeline 2 In the smoke gas circulation cover, under the suction action of the fan, smoke gas enters the sinter bed again to participate in sintering as combustion-supporting air; the sintering flue gas in the high-temperature flue gas main flue is divided into a high-temperature circulating flue gas and a high-temperature discharged flue gas, and the high-temperature circulating flue gas is mixed with oxygen and then enters SO through a high-temperature circulating flue gas pipeline 2 Region of rapidly decreasing concentration and SO 2 In a high-temperature flue gas circulation cover above a sinter bed in a region with rapidly increased concentration, under the suction action of a fan, flue gas enters the sinter bed again to participate in sintering as combustion-supporting air, and the high-temperature discharged flue gas passes through a high-temperature external flue gas discharge pipeline and is removed by high-temperature discharged flue gasAfter the dust collector enters the waste heat boiler to recover waste heat, the dust is deeply removed and discharged.
At least 1 layer of ammonia water nozzles are arranged on the side wall of the air box corresponding to the low-temperature flue gas main flue along the circumferential direction, ammonia water is sprayed into flue gas through the nozzles, the spray nozzles are inclined upwards, the included angle between the spraying direction of the sprayed ammonia water and the flowing direction of the flue gas is larger than 90 degrees, and in the air box, the sprayed ammonia water reacts with sulfur dioxide in the flue gas to generate ammonium sulfite.
The low temperature flue gas zone and SO 2 2-4 groups of air box flue gas outlets at the junction of the area with the rapidly increased concentration are respectively connected with a low-temperature flue gas main flue and a high SO flue through exchange valves 2 The flue gas main flue.
The high temperature flue gas zone and SO 2 2-4 groups of air box flue gas outlets at the junction of the areas with rapidly reduced concentration are respectively connected with high SO through exchange valves 2 A flue gas main flue and a high-temperature flue gas main flue.
At least 1 layer of ammonia water or liquid ammonia nozzles are circumferentially arranged on the side wall of the low-temperature flue gas pipeline, ammonia water or liquid ammonia is sprayed out of the nozzles, and the ammonia water or liquid ammonia is gasified into ammonia gas in the sintering flue gas, enters the pipeline mixer together with the sintering flue gas, is mixed and then enters the low-temperature flue gas circulation cover; at said high SO 2 At least 1 layer of oxygen nozzles are circumferentially arranged on the side wall of the circulating flue gas pipeline, oxygen is sprayed out from the nozzles, and the oxygen and sintering flue gas enter the pipeline mixer together to be mixed and then enter the high SO 2 The flue gas circulation cover; at least 1 layer of oxygen nozzles are arranged on the side wall of the high-temperature circulating flue gas pipeline along the circumferential direction, oxygen is sprayed out of the nozzles, and the oxygen and sintering flue gas enter the pipeline mixer to be mixed and then enter the high-temperature flue gas circulating cover.
Said high SO 2 The smoke circulating cover covers the low-temperature smoke area; the high-temperature flue gas circulation cover covers SO 2 Region of rapidly increasing concentration and SO 2 A region of rapidly decreasing concentration; the low-temperature flue gas circulating cover covers the high-temperature flue gas area.
The high-temperature flue gas circulation cover has high SO content 2 The flue gas circulation cover and the low-temperature flue gas circulation cover are uniformly provided with a plurality of airflow balance pipes, and the airflow balance pipes are smoothThe balance pipe is provided with a one-way flap valve, and air passes through the flap valve from top to bottom through the balance pipe to enter the sinter bed.
At least 1 layer of liquid ammonia or ammonia water nozzle is installed along circumference on the regional bellows lateral wall of high temperature flue gas to spout liquid ammonia or ammonia water into the flue gas through the nozzle, the nozzle jet orifice slope upwards, make spun liquid ammonia or ammonia water directly spout in the bedding material in platform truck grate and grate clearance, or the contained angle of blowout direction and flue gas flow direction is greater than 90 degrees, in the bellows, the ammonia that spun liquid ammonia or ammonia water volatilize becomes mixes with the flue gas, and further takes place denitration reaction under the iron system polyoxide catalytic action that the smoke and dust particulate matter is rich in.
The high-temperature flue gas circulating cover has high SO content 2 A plurality of temperature monitors are arranged on the inner sides of the edges of the flue gas circulation cover and the low-temperature flue gas circulation cover, and monitoring signals are respectively connected with the high-temperature circulation flue gas fan and the high SO 2 The flue gas fan and the low-temperature circulating flue gas fan are interlocked.
When the temperature monitor monitors that the temperature of the airflow is higher than the room temperature, the air suction volume of the fan corresponding to the circulating cover is reduced, and the air suction volume of the downstream fan of the airflow is increased.
And increasing the length of the high-temperature smoke region by adjusting the thickness of a sintering material layer or the advancing speed of a trolley of the sintering machine, wherein the increased length of the high-temperature smoke region is equivalent to that of the low-temperature smoke region, the low-temperature smoke region accounts for 40-43% of the total length of the sintering machine, and the increased length of the high-temperature smoke region accounts for 42-45% of the total length of the sintering machine.
By reducing the thickness of the sintering material layer by 5-10 percent or reducing the traveling speed of the sintering machine trolley by 5-10 percent.
The sintering flue gas is collected through a low-temperature flue gas main flue and a high-temperature flue gas main flue respectively; the low-temperature flue gas main flue collects sintering flue gas in an ignition area and low-temperature sintering flue gas which is close to 60-70% of the ignition area in the low-temperature flue gas area, and the high-temperature flue gas main flue collects a high-temperature flue gas area and SO 2 Region of rapidly decreasing concentration, SO 2 Sintering flue gas in a region with rapidly increased concentration and a region with low temperature flue gas close to SO 2 Low-temperature sintering flue gas with the concentration of 30-40% in the rapid increase area; the sintering flue gas in the low-temperature flue gas main flue enters the sinter cooling furnace from a cooling gas inlet of the sinter cooling furnace after being desulfurized by excessive ammonia water sprayed into the bellows; the sintering flue gas in the high-temperature flue gas main flue is mixed with oxygen and then enters a low-temperature flue gas area and SO 2 The concentration is quickly increased in the high-temperature flue gas circulation cover above the sinter bed, and under the suction action of the fan, the flue gas enters the sinter bed again to be used as combustion-supporting air to participate in sintering.
The low temperature flue gas region and SO 2 2-4 groups of air box smoke outlets at the junction of the areas with the rapidly increased concentration are respectively connected with a low-temperature smoke main flue and a high-temperature smoke main flue through exchange valves.
The high-temperature flue gas circulation cover covers the whole low-temperature flue gas area and SO 2 A region of rapidly increasing concentration.
The hot sinter charging smoke dust at the top of the sinter cooling furnace is introduced into SO 2 And under the suction action of a fan, the low-temperature flue gas enters the sinter bed to be used as combustion-supporting air to participate in sintering in the low-temperature flue gas circulation cover above the sinter bed in the concentration rapid reduction area and the high-temperature flue gas area.
The trolley and the sintering mixture run from the head to the tail in an inclined upward manner, and the sintering airflow and the sintering flame frontal surface are perpendicular to the travelling direction of the trolley and obliquely pass through the sintering material layer downwards.
The trolley and the sintering mixture on the trolley run from the head to the tail in an inclined mode, and the inclination is 5-15%.
The inventors have studied and found that, in the aforementioned 5 zones of the sintering machine, the sintering flue gas SO generated in the ignition zone and the low-temperature flue gas zone 2 The concentration is low and is less than 100mg/m 3 The NOx concentration is higher, generally 400mg/m 3 The above; SO (SO) 2 Flue gas SO generated in area with rapidly increased concentration 2 The concentration is from 100mg/m 3 The following rapid increase to 2000mg/m 3 Above (the highest value is related to the sulfur content of the sintering mixture and the sintering process parameters), the concentration of the contained NOx begins to decrease, but the decrease trend is not large; SO (SO) 2 Flue gas S generated in area with rapidly reduced concentrationO 2 The concentration is from 2000mg/m 3 The above quickly decreases to 50mg/m 3 About, the concentration of NOx contained in the solution rapidly decreases from 300mg/m 3 Quickly decreases to 50mg/m 3 The following; flue gas generated in the high-temperature flue gas area and containing SO 2 And NOx concentration is less than 50mg/m 3 。
The research of the inventor further discovers that in a low-temperature flue gas area, the sintering flue gas temperature is lower, about 80 ℃; the flue gas has high humidity and is in a saturated state; the concentration of sulfur dioxide in the flue gas is lower.
Aiming at the problems in the background technology, the characteristics of different sintering flue gas properties in different areas of a sintering machine are combined to reduce the emission of SO in the sintering process 2 The inventor makes the following improvements: at least 1 layer of ammonia water nozzle is installed along the circumference on the bellows lateral wall that low temperature flue gas main flue corresponds to spout into the aqueous ammonia in to the flue gas through the nozzle, the slope of nozzle blowout mouth upwards makes spun aqueous ammonia blowout direction and flue gas flow direction's contained angle be greater than 90 degrees to aqueous ammonia droplet and the more abundant mixture of flue gas, and react with the sulfur dioxide in the flue gas and generate ammonium sulfite, realize the online desulfurization of sintering flue gas.
According to analysis on the principle of belt type air draft sintering, after the sintering material is ignited at high temperature, the fuel in the sintering material layer is continuously combusted to form a combustion layer. The flame front moves downwards continuously along with the proceeding of air draft sintering. The fuel in the sinter material is burnt to release a large amount of heat, so that the minerals in the material layer are melted, and the generated molten liquid phase is cooled and recrystallized (1000-1100 ℃) to be solidified into the sinter with a mesh structure, namely the sinter layer, along with the downward movement of the burning layer and the passing of cold air. The main change in this layer is solidification of the melt, with crystallization and precipitation of new minerals. As sintering proceeds, the gas stream is preheated through the sinter bed while the sinter is cooled and the suboxides may be reoxidized upon contact with air.
Because the combustion air of the combustion layer is preheated by the sintering ore layer, the temperature of the layer is high, and the temperature of the flame front reaches 1350-1600 ℃, so that the minerals are softened, melted and bonded into blocks. In addition to the combustion reaction, the layer also undergoes reactions such as melting, reduction, oxidation of solid materials, and decomposition of limestone and sulfides.
When high-temperature flue gas generated after fuel in the combustion layer is combusted downwards passes through the sinter layer, the mixture at the lower part is quickly preheated to the ignition temperature, generally 400-800 ℃, and then the preheating layer is formed. Solid phase reaction begins in the layer, crystal water and partial carbonate and sulfate are decomposed, and magnetite is partially oxidized.
The flue gas passing through the preheating layer continuously downwards passes through the sintering material layer, and the lower layer of sintering mixture is quickly dried to form a drying layer. The temperature of the layer rises to above 100 ℃ quickly, a large amount of free water in the mixture evaporates, and the thickness of the layer is l 0-30 mm generally.
In actual production, the drying layer is difficult to separate from the preheating layer, and is generally referred to as a dry preheating layer. The material balls in the layer are rapidly heated, rapidly dried and easily damaged, and the air permeability of the material layer is deteriorated.
The hot waste gas from the drying layer contains a large amount of moisture, and when the material temperature is lower than the dew point temperature of the water vapor, the water vapor in the waste gas can be condensed again, so that the moisture in the mixed material is increased greatly to form an over-wet layer. The moisture in the layer is too much, so that the air permeability of the material layer is deteriorated, and the sintering speed is reduced.
When the flue gas passing through the over-wet layer downwards passes through the sintering mixture, the flue gas is continuously cooled by the material layer, the temperature of the flue gas leaving the sintering mixture layer is about 80 ℃, and the humidity is in a relative saturation state.
After entering the bellows, influenced by ambient temperature, the temperature can further reduce, and the flue gas is in humidity oversaturation state. At this time, the ammonia water is sprayed into the flue gas, the temperature of the flue gas is reduced again under the influence of the temperature of the ammonia water and the volatilization and heat absorption of the ammonia water, and the humidity is further increased. The temperature of the flue gas is 70-80 ℃. The temperature and humidity environment is very favorable for the reaction of sulfur dioxide in the flue gas and ammonia gas, and the generated ammonium sulfite is very easy to crystallize on the surface of fine particles under the induction action of the particles of the flue gas.
In order to ensure that the concentration of sulfur dioxide and NOx in the finally discharged sintering flue gas meets the requirement of emission standard, the sintering flue gas generated in each area is subjected to quality-divided circulation, and the sintering flue gas of the finally discharged part is totally discharged byAnd a high-temperature flue gas main flue corresponding to the high-temperature flue gas area is led out. Firstly, SO with high concentration of sulfur dioxide and NOx is contained 2 Region of rapidly increasing concentration and SO 2 The sintering flue gas in the area with the rapidly reduced concentration circularly enters the low-temperature flue gas area to participate in sintering again after oxygen is supplemented, and sulfur dioxide and NOx are enriched in the sintering process.
The inventor further researches and discovers that as the flue gas circulation is carried out, in a low-temperature flue gas area, the temperature and the humidity of sintering flue gas are basically kept unchanged, but the concentration of sulfur dioxide in the flue gas is obviously increased and is kept at 3000mg/m of 2000- 3 . The ammonia water is sprayed into the flue gas through the ammonia water nozzle, and the desulfurization efficiency can reach more than 80%.
The inventor further researches to find that the temperature of sintering flue gas entering the wind box is not higher than 80 ℃ as long as the sintering material layer exists. Because the moisture in the flue gas is condensed in the over-temperature layer, the sintering mixture is also in a high humidity state, CaO in the mixture is digested by the condensed water, and the CaO becomes a desulfurizing agent to absorb sulfur dioxide in the flue gas; meanwhile, the surface layer of the mixture which is highly wetted also has an absorption effect on sulfur dioxide in the flue gas.
After the flue gas enters the bellows, because the ammonia water that spouts atomizes and volatilizes the heat absorption, the flue gas temperature further reduces, and the flue gas is wet further to be increased relatively, promotes sulfur dioxide in the flue gas and ammonia reaction, improves the desulfurization efficiency of flue gas.
In order to reduce the external discharge of the flue gas, a part of the flue gas from the high-temperature flue gas main flue is led out to enter the inner area of a circulating flue gas hood which is circularly entered after oxygen supplement and then participates in SO again 2 Region of rapidly increasing concentration and SO 2 Sintering of the region of rapidly decreasing concentration. The other part is directly led out for further dust removal and discharge after dust removal and waste heat utilization.
Aiming at the problems in the background art, the inventor makes the following improvements in order to reduce the emission of NOx in the sintering process by combining the characteristics of different sintering flue gas properties of different regions of a sintering machine: using iron-based polyoxides, e.g. gamma-Fe, enriched in sinter 2 O 3 To NH 3 SCR denitration has the characteristic of strong catalytic activity, and the low temperature is generatedThe sintering flue gas of the flue gas main flue enters a low-temperature flue gas pipeline through dust removal, ammonia water or liquid ammonia is sprayed into the low-temperature flue gas pipeline, the flue gas and ammonia gas formed by volatilization of the sprayed ammonia water or liquid ammonia are mixed in a pipeline mixer and then are guided to the upper part of a sintering material layer of a high-temperature flue gas area of a sintering machine, under the suction action of a fan in the area, the flue gas enters the sintering material layer again, the temperature is raised in the sintering material layer, the flue gas mixed with the ammonia gas is heated to reach the reaction temperature of SCR and SNCR, and the reduction denitration reaction of NOx is carried out under the catalytic action of the sintering material layer.
Further, at least 1 layer of liquid ammonia or ammonia water nozzles are circumferentially arranged on the side wall of the air box in the high-temperature flue gas area, liquid ammonia or ammonia water is sprayed into the flue gas through the nozzles, the nozzles are upwards inclined, the sprayed liquid ammonia or ammonia water is directly sprayed into the grate of the trolley and a grate gap bedding material, or the included angle between the spraying direction and the flow direction of the flue gas is larger than 90 degrees, in the air box, the ammonia gas formed by volatilization of the sprayed liquid ammonia or ammonia water is mixed with the flue gas, the denitration reaction is further carried out under the catalysis of iron-based polyoxide rich in smoke particles, and the flue gas after the reaction is discharged after waste heat recovery and dust removal.
Further investigation revealed that in said SO 2 The concentration is reduced the area and high-temperature flue gas area fast, and the fuel is all burnt in the sintering bed, and the sintering bed becomes the sintering deposit entirely, the sintering deposit porosity is high, and the gas resistance is little for the gas pocket diameter is big. When the circulating flue gas enters the sinter bed, the circulating flue gas exchanges heat with the sinter to raise the temperature, and simultaneously NOx in the flue gas and the sprayed ammonia can perform reduction denitration reaction under the catalytic action of iron-based polyoxide rich in the sinter bed.
In order to ensure the smooth circulation of the flue gas and the balance of the flue gas quantity, the invention adopts 3 balance schemes, one scheme is that a plurality of temperature monitors are arranged on the inner side of the edge of the flue gas circulation cover, the second scheme is that the flue gas circulation cover is provided with an airflow balance pipe, a one-way flap valve is arranged on the airflow balance pipe, and the third scheme is that a low-temperature flue gas area and SO are arranged 2 The flue gas outlets of 2-4 groups of air boxes at the junction of the areas with rapidly increased concentration are connected with the low-temperature flue gas main flue and the high SO through exchange valves 2 The flue gas main flue switches the flow direction of the flue gas through an exchange valve to connect a high-temperature flue gas area and SO 2 The flue gas outlets of 2-4 groups of air boxes at the junction of the areas with rapidly reduced concentration are connected with the high-temperature flue gas main flue and the high SO through exchange valves 2 The flue gas main flue and the flue gas flow direction is switched through the exchange valve.
The temperature monitor is used for interlocking the temperature signal monitored by the monitor with the high-temperature flue gas circulating fan and the low-temperature flue gas exhaust fan. Due to the high SO and the main flue of high-temperature flue gas 2 The flue gas temperature of the flue gas main flue is obviously higher than the ambient air temperature, and enters the high-temperature flue gas circulating hood and the high SO 2 If the smoke of the smoke circulating cover overflows, the temperature is higher, which indicates that the circulating smoke amount is too much, at the moment, the air draft amount of the corresponding main flue fan can be changed, and meanwhile, the exchange valve is adjusted to change the flow direction of the smoke.
The function of the one-way flap valve is to provide an air inflow channel for the smoke circulating cover and simultaneously prevent the smoke entering circularly from overflowing. When the amount of the smoke gas entering in the circulation mode is insufficient, the area below the circulation cover is in a micro negative pressure state, the one-way flap valve is opened at the moment, and air passes through the flap valve from top to bottom through the balance pipe and enters a sinter bed; when the amount of the smoke entering in the circulating cover is surplus, the pressure of the area below the circulating cover is higher than the external atmospheric pressure of the circulating cover, the one-way flap valve is closed, and the surplus smoke can only overflow through the edge of the smoke circulating cover.
Low temperature flue gas zone and SO 2 The switching signals of the exchange valves of 2-4 groups of windbox smoke outlets at the boundary of the area with the rapid concentration reduction come from temperature monitors arranged on the inner side of the edge of the smoke circulating cover. When the temperature detected by the temperature monitor is higher than the room temperature, the exchange valve switches the flue gas to the low-temperature flue gas main flue, and otherwise, the flue gas is switched to the high SO flue gas main flue 2 A flue gas main flue; also, high temperature flue gas zone and SO 2 The switching process of the exchange valves of the smoke outlets of the 2-4 groups of windboxes at the boundary of the area with the rapid concentration reduction is also the same.
In order to further simplify the flue gas circulation path and reduce the content of NOx in the discharged flue gas, the inventor researches and further discovers that the flue gas circulation process route can be greatly simplified by using the shaft kiln for cooling the hot sintering ore as a denitration reactor of the flue gas, and the flue gas circulation process has a remarkable denitration cost advantage. After waste heat recovery, liquid ammonia or ammonia water is sprayed into the pipeline again, the flue gas is mixed by a mixer and then enters the sinter cooling furnace as hot sinter cooling air, and after heat exchange with the hot sinter cooling furnace and temperature rise, NOx reduction denitration reaction is carried out under the catalytic action of iron-based polyoxide rich in the sinter.
In order to reduce the amount of discharged flue gas and simplify the flue gas circulation process, a low-temperature flue gas main flue and a high-temperature flue gas main flue are adopted to collect sintering flue gas. The low-temperature flue gas main flue collects sintering flue gas in an ignition area and 60-70% of low-temperature sintering flue gas in a low-temperature flue gas area close to the ignition area, and low-temperature flue gas in the rest low-temperature flue gas area enters the high-temperature flue gas main flue. All the sintering flue gas in the rest area enters a high-temperature flue gas main flue, and simultaneously, all the sintering flue gas circularly enters a low-temperature flue gas area and SO 2 In the high-temperature flue gas circulation cover above the sinter bed in the region with the rapidly increased concentration, under the suction action of the fan, the flue gas enters the sinter bed again to participate in sintering as combustion-supporting air. In the circulation, the sintering flue gas generated in the low-temperature flue gas area directly enters the internal circulation of the high-temperature flue gas main flue, and the flue gas of the high-temperature flue gas main flue is completely introduced into the low-temperature flue gas area and SO 2 The external circulation of the region with the quickly increased concentration increases the circulation amount of the flue gas and reduces the amount of the discharged flue gas. On the basis, in order to ensure the stability of circulation and avoid the overflow of circulating flue gas, the circulating flue gas is in a low-temperature flue gas area and SO 2 2-4 groups of air box smoke outlets at the junction of the areas with the rapidly increased concentration are respectively connected with a low-temperature smoke main flue and a high-temperature smoke main flue through exchange valves, and the flow direction of smoke in the air boxes is timely switched according to process requirements and stable operation conditions.
Has the advantages that:
(1) the discharge amount of sintering flue gas is greatly reduced, and the discharged flue gas amount is reduced to about 30 percent of the original discharge amount. The flow direction of the flue gas is switched through the sintering flue gas quality-divided circulation and the flue gas outlet exchange valve of the air box, so that the circulation quantity of the flue gas is increased, and the external discharge quantity of the flue gas is reduced.
(2) Need not newly-built sintering flue gas SOx/NOx control facility, save SOx/NOx control equipment input. By utilizing the characteristics of lower sintering flue gas temperature and high humidity of a low-temperature flue gas area of the head of the sintering machine, ammonia water is sprayed into the flue gas and reacts with sulfur dioxide in the flue gas to generate ammonium sulfite, so that online desulfurization of the sintering flue gas is realized. A new desulfurization facility is not needed, so that the investment of desulfurization equipment is saved; by utilizing the characteristics of higher temperature of a sintering ore layer, high porosity, large pore diameter and small gas resistance of a high-temperature flue gas area at the tail part of a sintering machine, flue gas containing NOx enters the sintering ore layer to exchange heat with the sintering ore and heat up, and NOx in the flue gas and injected ammonia can perform reduction denitration reaction under the catalytic action of iron-based polyoxide rich in the sintering ore layer. And an external denitration catalyst is not needed, the investment of denitration equipment is not needed, and the investment and the operation cost of denitration are greatly reduced.
(3) The flue gas circulation operation stability is high, and the flue gas volume balancing capability is strong. The temperature monitor is arranged on the inner side of the edge of the flue gas circulation cover, the flue gas circulation cover is provided with an airflow balance pipe, a one-way flap valve, a low-temperature flue gas area and SO 2 Flue gas outlet of 2-4 exhaust bellows at the junction of the rapid concentration rise area, high-temperature flue gas area and SO 2 The flue gas outlet of the 2-4 rows of air boxes at the junction of the areas with the rapidly reduced concentration switches the flow direction of flue gas through an exchange valve, monitors and ensures the stable operation of flue gas circulation. Simultaneously, SO generated in a low-temperature flue gas area is treated 2 Part of the flue gas with high concentration is collected and enters high SO 2 Flue gas main flue and SO collected from the main flue 2 Region of rapidly increasing concentration and SO 2 Mixing of the sintering flue gas in the region of rapidly decreasing concentration while supplementing oxygen for recirculation into the high SO above the low temperature flue gas region 2 The flue gas circulates in the cover, and under the suction action of the fan, the flue gas enters the sinter bed again for recycling. The oxygen content of the circulating flue gas can be balanced by supplementing oxygen; by introducing a portion of the flue gas from the low temperature flue gas zone into the high SO 2 The flue gas main flue forms a part of internal circulation path, which is beneficial to improving the stability of flue gas circulation and the balance of flue gas quantity.
Drawings
FIG. 1 is a process flow diagram of the present invention.
FIG. 2 is an illustration of example 2.
Wherein, 1-sintering machine trolley track, 1.1-tail bend, 1.2-head star wheel, 2-sintering machine, 2.1-trolley, 3-sintering mixture, 3.1-sinter bed, 3.2-sinter bed material, 4-1-high temperature circulation flue gas dust remover, 4-2-low temperature flue gas dust remover, 4-3-high temperature discharge flue gas dust remover, 4-4-high SO 2 A flue gas dust remover, a 5-1-high temperature circulating flue gas fan, a 5-2-low temperature circulating flue gas fan, a 5-3-high temperature exhaust flue gas fan, and a 5-4-high SO 2 A flue gas fan, 6-1-a high-temperature circulating flue gas pipeline, 6-2-a low-temperature flue gas pipeline, 6-3-a high-temperature external flue gas pipeline, and 6-4-high SO 2 Flue gas pipeline, 7-1-high temperature flue gas pipeline mixer, 7-2-low temperature flue gas pipeline mixer, 7-3-high SO 2 Flue gas pipeline mixer, 8.1-low temperature flue gas circulation cover, 8.2-low temperature flue gas balance pipe, 8.3-low temperature flue gas one-way valve, 9.1-high temperature flue gas circulation cover, 9.2-high temperature flue gas balance pipe, 9.3-high temperature flue gas one-way valve, 10.1-high SO flue gas 2 Flue gas recirculation hood, 10.2-high SO 2 Flue gas balance tube, 10.3-high SO 2 A flue gas one-way valve, 11-an ignition system, 12-a blanking chute, 13-a blanking hopper, 14-a distributing machine, 15-an air box, 16-1-a low-temperature flue gas main flue and 16-2-high SO 2 The method comprises the following steps of (1) flue gas main flue, 16-3-high temperature flue gas main flue, 17.1-ammonia water nozzle, 17.2-sprayed ammonia water mist, 18-discharged flue gas deduster, 19-waste heat boiler, 20-exchange valve, 21-chimney and 23-sinter cooling furnace.
Detailed Description
The solution according to the invention is further illustrated by way of example with reference to the accompanying drawings.
Example 1
Referring to FIG. 1, including sintering gas flow in fans (including high temperature circulating flue gas fan 5-1, low temperature circulating flue gas fan 5-2, high SO) 2 The flue gas fan 5-4) passes through a sinter bed 3.1 of the sinter mixture 3, a sinter bed material 3.2, a sintering machine 2, a trolley grate 2.1 and an air box 15 below the trolley 2.1 to feed under the suction action of the flue gas fanEnters a main flue (comprising a low-temperature flue gas main flue 16-1 and a high SO 2 A flue gas main flue 16-2 and a high-temperature flue gas main flue 16-3); the sintering machine 2 is divided into an ignition area, a low-temperature flue gas area and SO in turn along the traveling direction of a trolley 2.1 of the sintering machine 2 2 Region of rapid rise in concentration, SO 2 A rapid concentration reduction area and a high-temperature flue gas area are 5 areas. The sinter mixture 3 is uniformly distributed on the trolley 2.1 of the sintering machine 2 through a feeding chute 12 by a feeding hopper 13 and a distributing machine 14. Under the push of the rear trolley 2.1, the trolley 2.1 loaded with the sinter bed 3.1 and the sinter bed 3.2 advances to the lower part of the ignition system 11 and ignites for sintering, and meanwhile, fans (comprising a high-temperature circulating flue gas fan 5-1, a low-temperature circulating flue gas fan 5-2 and a high-SO-content circulating flue gas fan) are arranged on the fans (comprising a high-temperature circulating flue gas fan 5-1, a low-temperature circulating flue gas fan 5-2 and a high-SO-content circulating flue gas fan) 2 And under the suction action of the flue gas fan 5-4), sintering airflow enters the sinter bed 3.1 to participate in sintering.
The length of the high-temperature smoke area is made to be equal to that of the low-temperature smoke area by reducing the thickness of the sinter bed 3.1 by 5-10% or reducing the advancing speed of the trolley 2.1 of the sintering machine 2 by 5-10%.
Sintering flue gas generated in the low-temperature flue gas area enters a low-temperature flue gas main flue 16-1, SO 2 Region of rapidly increasing concentration and SO 2 Sintering flue gas in a region with rapidly reduced concentration enters high SO 2 The flue gas main flue 16-2, the sintering flue gas generated in the high-temperature flue gas area enters the high-temperature flue gas main flue 16-3.
The flue gas from the high-temperature flue gas main flue 16-3 is divided into two parts, one part enters a high-temperature circulating flue gas pipeline 6-1 under the suction action of a high-temperature circulating flue gas fan 5-1, is dedusted by a high-temperature circulating flue gas deduster 4-1, is supplemented with oxygen, is mixed in a high-temperature flue gas pipeline mixer 7-1, enters a high-temperature flue gas circulating cover 9.1, and enters SO again 2 Region of rapidly increasing concentration and SO 2 The sinter bed 3.1 in the region with the rapidly reduced concentration participates in sintering; the other part of the waste heat is sucked by a high-temperature external exhaust smoke fan 5-3 and enters a high-temperature external exhaust smoke pipeline 6-3, is dedusted by a high-temperature external exhaust smoke deduster 4-3, enters a waste heat boiler 19 for recovering waste heat, is dedusted by an external exhaust smoke deduster 18 and is exhausted out of a chimney 21.
High SO 2 Flue gasFlue gas from the main flue 16-2 is in high SO 2 The flue gas enters high SO under the suction action of a flue gas fan 5-4 2 6-4 parts of flue gas pipeline passing through high SO 2 Supplementing oxygen after dedusting by the flue gas deduster 4-4 and keeping the oxygen at high SO 2 The mixed gas enters the high SO after being mixed by a flue gas pipeline mixer 7-3 2 In the flue gas circulation cover 10.1, the sinter bed 3.1 which enters the low-temperature flue gas area again participates in sintering, and SO is carried out 2 And NOx are enriched, the SO in the flue gas enters an air box 15 under the suction action of a low-temperature circulating flue gas fan 5-2, and the SO in the flue gas enters the air box 15 2 Reacting with ammonia in ammonia water mist 17.2 sprayed in the air box 15 to generate ammonium sulfite; the desulfurized flue gas enters a low-temperature flue gas pipeline 6-2, is dedusted by a low-temperature flue gas deduster 4-2, is sprayed with ammonia water or liquid ammonia again in the low-temperature flue gas pipeline 6-2, is mixed by a low-temperature flue gas pipeline mixer 7-2, enters a low-temperature flue gas circulating cover 8.1, and enters a sinter bed 3.1 in a high-temperature flue gas area again to participate in sintering.
When the circulating low-temperature flue gas is surplus, a temperature monitor (not marked in the figure) arranged on the inner side of the edge of the low-temperature flue gas circulating cover 8.1 is used for measuring that the temperature is higher than the room temperature, a change valve 20 is switched, and the flue gas in a low-temperature flue gas area is switched to be high SO 2 16-2 of the flue gas main flue, and reducing the speed by frequency conversion at the same time to reduce the air suction amount of the low-temperature circulating flue gas fan 5-2; also, the high-temperature flue gas enters a high-temperature flue gas circulating hood 9.1 and high SO 2 When the smoke circulating cover 10.1 is rich in smoke, the operation is carried out according to the situation.
At least 1 layer of ammonia water nozzles 17.1 are circumferentially arranged on the side wall of the air box 15 in the high-temperature flue gas area, ammonia water mist 17.2 is sprayed into the air box 15 through the ammonia water nozzles 17.1, the spray ports of the nozzles 15 are inclined upwards, the sprayed ammonia water mist 17.2 is directly sprayed into a grate of a trolley 2.1 and a grate bottom material 3.2 in a gap of the grate, or the included angle between the spraying direction and the flue gas flowing direction is larger than 90 degrees, in the air box 15, ammonia gas volatilized from the sprayed ammonia water mist 17.2 is mixed with the flue gas and further subjected to denitration reaction under the catalysis of iron-based polyoxide rich in smoke particles, and the flue gas after the reaction is subjected to waste heat recovery and dust removal and then is discharged outside.
The technical scheme reduces the external discharge capacity of sintering flue gas by 70 percent.
Example 2
Referring to fig. 2, sintering airflow passes through a sinter bed 3.1 of a sintering mixture 3, a sintering bed material 3.2, a trolley 2.1 grate of a sintering machine 2 and an air box 15 below the trolley 2.1 to enter a main flue (comprising a low-temperature flue gas main flue 16-1 and a high-temperature flue gas main flue 16-3) under the suction action of a fan (comprising a high-temperature circulating flue gas fan 5-1 and a low-temperature circulating flue gas fan 5-2); the sintering machine 2 is divided into an ignition area, a low-temperature flue gas area and SO in sequence along the advancing direction of a trolley 2.1 of the sintering machine 2 2 Region of rapidly increasing concentration, SO 2 A rapid concentration reduction area and a high-temperature flue gas area are 5 areas. The sinter mixture 3 is uniformly distributed on the trolley 2.1 of the sintering machine 2 through a feeding chute 12 by a feeding hopper 13 and a distributing machine 14. Under the push of the rear trolley 2.1, the trolley 2.1 loaded with the sinter bed 3.1 and the sinter bed 3.2 moves to the lower part of the ignition system 11 and ignites for sintering, and meanwhile, under the suction action of fans (including a high-temperature circulating flue gas fan 5-1 and a low-temperature circulating flue gas fan 5-2), sinter airflow enters the sinter bed 3.1 to participate in sintering.
Sintering flue gas generated in the low-temperature flue gas area enters a low-temperature flue gas main flue 16-1; SO (SO) 2 Region of rapidly increasing concentration, SO 2 And sintering flue gas generated in the concentration rapid reduction area and the high-temperature flue gas area enters the high-temperature flue gas main flue 16-3.
The flue gas from the high-temperature flue gas main flue 16-3 enters a high-temperature circulating flue gas pipeline 6-1, is dedusted by a high-temperature circulating flue gas deduster 4-1, is supplemented with oxygen, is mixed in a high-temperature flue gas pipeline mixer 7-1, enters a high-temperature flue gas circulating cover 9.1, and enters a low-temperature flue gas area and SO again 2 The sinter bed 3.1 in the region of the rapidly increasing concentration takes part in the sintering.
Low temperature flue gas zone and SO 2 The flue gas in the area with the rapidly increased concentration enters a low-temperature flue gas pipeline 6-2 after being desulfurized by ammonia gas in an air box 15, is dedusted by a low-temperature flue gas deduster 4-2, is sprayed with ammonia water or liquid ammonia again in the low-temperature flue gas pipeline 6-2, is mixed by a low-temperature flue gas pipeline mixer 7-2, and then enters a sinter cooling furnace 23 as hot sinter cooling air, exchanges heat with hot sinter to be heated, and is subjected to NOx reduction under the catalytic action of iron-based polyoxide rich in the sinterAnd (4) carrying out denitration reaction.
The rest is the same as embodiment 1.
Referring to FIG. 1, including sintering gas flow in fans (including high temperature circulating flue gas fan 5-1, low temperature circulating flue gas fan 5-2, high SO) 2 The flue gas fan 5-4) passes through a sinter bed 3.1 of the sinter mixture 3, a sinter bed material 3.2, a sintering machine 2, a trolley grate 2.1 and an air box 15 below the trolley 2.1 under the suction action of the flue gas fan and enters a main flue (comprising a low-temperature flue gas main flue 16-1 and a high-SO-content flue gas main flue) 2 A flue gas main flue 16-2 and a high-temperature flue gas main flue 16-3); the sintering machine 2 is divided into an ignition area, a low-temperature flue gas area and SO in sequence along the advancing direction of a trolley 2.1 of the sintering machine 2 2 Region of rapid rise in concentration, SO 2 A concentration rapid reduction area and a high-temperature smoke area are 5 areas. The sinter mixture 3 is uniformly distributed on the trolley 2.1 of the sintering machine 2 through a feeding chute 12 by a feeding hopper 13 and a distributing machine 14. Under the push of the rear trolley 2.1, the trolley 2.1 loaded with the sinter bed 3.1 and the sinter bed 3.2 advances to the lower part of the ignition system 11 and ignites for sintering, and meanwhile, fans (comprising a high-temperature circulating flue gas fan 5-1, a low-temperature circulating flue gas fan 5-2 and a high-SO-content circulating flue gas fan) are arranged on the fans (comprising a high-temperature circulating flue gas fan 5-1, a low-temperature circulating flue gas fan 5-2 and a high-SO-content circulating flue gas fan) 2 And under the suction action of the flue gas fan 5-4), sintering airflow enters the sinter bed 3.1 to participate in sintering.
The trolley 2.1 and the sintering mixture 3 run from the head to the tail in an inclined upward manner, the sintering airflow and the sintering flame frontal surface are vertical to the advancing direction of the trolley 2.1, and the sintering mixture layer 3.1 and the sintering bottom material 3.2 penetrate through in an inclined downward manner.
The sintering mixture 3 on the trolley 2.1 and the trolley 2.1 runs from the head to the tail in an inclined manner, and the inclination is 5-15%.
The rest is the same as embodiment 1.
Claims (18)
1. The sintering process based on the emission reduction of the smoke pollutants of the sintering smoke by the mass-divided cycle coupling comprises a sintering machine and a trolley thereof, a sintering airflow, sintering smoke formed after combustion-supporting sintering, a sintering mixture and sintering ore formed after sintering; the sintering airflow enters a sintering mixture layer for combustion supporting and sintering under the suction action of a fan to form sintering flue gas, and the sintering flue gas penetrates through the sintering mixture layer and is sinteredSintering a trolley grate and an air box below the trolley into a main flue, sintering the sintering mixture at a high temperature under the combustion supporting of sintering airflow to form sinter, and discharging the sinter into a sinter cooling furnace along with the trolley at a fixed bend at the tail of the sintering machine; dividing the sintering machine into an ignition area, a low-temperature flue gas area and an SO area along the travelling direction of a trolley of the sintering machine in sequence 2 Region of rapid rise in concentration, SO 2 5 areas of the rapid concentration reduction area and the high-temperature flue gas area, and is characterized in that the sintering flue gas respectively passes through the low-temperature flue gas main flue and the high-SO flue gas main flue 2 The main flue gas flue and the main flue gas flue for high-temperature flue gas are collected, the main flue gas flue for low-temperature flue gas collects sintering flue gas in an ignition area, the low-temperature flue gas area is close to the low-temperature sintering flue gas in the length range of 70-80% of the ignition area, and the high SO 2 Collecting SO from flue gas main flue 2 Region of rapidly decreasing concentration and SO 2 Sintering flue gas in a region with rapidly increased concentration and a region with low temperature flue gas close to SO 2 The low-temperature sintering flue gas with the concentration rapidly increased within the length range of 20-30%, and the high-temperature flue gas main flue collects the high-temperature sintering flue gas in the high-temperature flue gas area; the sintering flue gas in the low-temperature flue gas main flue is desulfurized by spraying excessive ammonia water and then is introduced into the low-temperature flue gas circulating cover through the low-temperature flue gas pipeline; the low-temperature flue gas circulating cover covers a high-temperature flue gas area; said high SO 2 The sintering flue gas in the flue gas main flue is mixed with oxygen and then is subjected to high SO 2 High SO above a sinter bed entering a low-temperature flue gas area through a flue gas circulation pipeline 2 In the smoke gas circulation cover, under the suction action of the fan, smoke gas enters the sinter bed again to participate in sintering as combustion-supporting air; the sintering flue gas in the high-temperature flue gas main flue is divided into a high-temperature circulating flue gas and a high-temperature discharged flue gas, and the high-temperature circulating flue gas is mixed with oxygen and then enters SO through a high-temperature circulating flue gas pipeline 2 Region of rapidly decreasing concentration and SO 2 In a high-temperature flue gas circulation cover above a sinter bed in a region with rapidly increased concentration, under the suction action of a fan, flue gas enters the sinter bed again to participate in sintering as combustion-supporting air, and the high-temperature discharged flue gas enters a waste heat boiler through a high-temperature outer exhaust gas pipeline and a high-temperature discharged flue gas dust remover to recover waste heat and then is deeply discharged into the waste heat boilerAnd (4) dedusting and discharging.
2. The sintering process based on emission reduction of pollutants in flue gas coupling through sintering flue gas quality-divided circulation according to claim 1, wherein at least 1 layer of ammonia water nozzles are circumferentially installed on a side wall of the air box corresponding to the low-temperature flue gas main flue, ammonia water is sprayed into the flue gas through the nozzles, a spraying port of each nozzle is inclined upwards, an included angle between a spraying direction of the sprayed ammonia water and a flowing direction of the flue gas is larger than 90 degrees, and the sprayed ammonia water reacts with sulfur dioxide in the flue gas to generate ammonium sulfite in the air box.
3. The sintering process based on coupling of flue gas pollutant reduction by sintering flue gas mass-divided circulation and emission reduction according to claim 1, wherein the low-temperature flue gas region and SO 2 2-4 groups of air box flue gas outlets at the junction of the area with the rapidly increased concentration are respectively connected with a low-temperature flue gas main flue and a high SO flue through exchange valves 2 The flue gas main flue.
4. The sintering process based on coupling of flue gas pollutant reduction by sintering flue gas mass-divided circulation and emission reduction according to claim 1, wherein the high temperature flue gas region and SO 2 2-4 groups of air box flue gas outlets at the junction of the areas with rapidly reduced concentration are respectively connected with high SO through exchange valves 2 A flue gas main flue and a high-temperature flue gas main flue.
5. The sintering process based on emission reduction of flue gas pollutants generated by coupling sintering flue gas in a mass-sharing circulation manner according to claim 1, wherein at least 1 layer of ammonia water or liquid ammonia nozzles are circumferentially arranged on the side wall of the low-temperature flue gas pipeline, ammonia water or liquid ammonia is sprayed out of the nozzles, and the ammonia water or liquid ammonia is gasified into ammonia gas in the sintering flue gas, enters the pipeline mixer together with the sintering flue gas, is mixed with the ammonia gas, and then enters the low-temperature flue gas circulation cover; at said high SO 2 At least 1 layer of oxygen nozzles are arranged on the side wall of the flue gas circulation pipeline along the circumferential direction, oxygen is sprayed out from the nozzles, and the oxygen and sintering flue gas enter the pipeline mixer together to be mixed and then enter the high SO 2 The flue gas circulation cover; at the high temperature circulating flue gas pipeAt least 1 layer of oxygen nozzles are arranged on the side wall along the circumferential direction, oxygen is sprayed out by the nozzles, and the oxygen and sintering flue gas enter the pipeline mixer together to be mixed and then enter the high-temperature flue gas circulation cover.
6. The sintering process based on coupling of sintering flue gas mass-separation cycle with flue gas pollutant reduction according to claim 1 or 5, wherein the high SO is 2 The flue gas circulating cover covers the low-temperature flue gas area; the high-temperature flue gas circulation cover covers SO 2 Region of rapidly increasing concentration and SO 2 A region of rapidly decreasing concentration.
7. The sintering process based on coupling of sintering flue gas quality-divided cycle with flue gas pollutant reduction according to claim 5, wherein the high-temperature flue gas circulation hood, high SO 2 The flue gas circulation cover with a plurality of airflow balance pipes of equipartition on the low temperature flue gas circulation cover, install one-way flap valve on the airflow balance pipe, the air passes through the balance pipe is by the upward flap valve entering sinter bed that passes.
8. The sintering process based on emission reduction of pollutants in flue gas coupling through sintering flue gas mass-separation and circulation as claimed in claim 1, wherein at least 1 layer of liquid ammonia or ammonia water nozzles are circumferentially installed on the side wall of the air box in the high-temperature flue gas area, and liquid ammonia or ammonia water is sprayed into the flue gas through the nozzles, and the nozzle outlets are inclined upwards, so that the sprayed liquid ammonia or ammonia water is directly sprayed into the bedding material between the grate of the trolley and the grate gap, or the included angle between the spraying direction and the flue gas flowing direction is greater than 90 degrees, and in the air box, the ammonia gas volatilized from the sprayed liquid ammonia or ammonia water is mixed with the flue gas and further subjected to denitration reaction under the catalytic action of iron-based polyoxide rich in smoke particles.
9. The sintering process based on coupling of sintering flue gas quality-divided cycle with flue gas pollutant reduction according to claim 5, wherein the high-temperature flue gas circulation hood, high SO 2 Flue gas circulation cover and a plurality of temperature monitors are arranged on inner side of edge of low-temperature flue gas circulation coverThe monitoring signal is respectively connected with the high-temperature circulating flue gas fan and the high SO 2 The flue gas fan and the low-temperature circulating flue gas fan are interlocked.
10. The sintering process based on emission reduction of pollutants in flue gas from mass-separation and cyclic coupling of sintering flue gas as claimed in claim 9, wherein when the temperature monitor monitors that the temperature of the gas flow is higher than room temperature, the air suction volume of the fan corresponding to the cyclic cover is reduced, and the air suction volume of the fan downstream of the gas flow is increased.
11. The sintering process based on coupling of flue gas pollutant emission reduction by sintering flue gas mass-separation and circulation according to claim 1, wherein the length of the high-temperature flue gas area is increased by adjusting the thickness of a sintering material layer or the traveling speed of a trolley of a sintering machine, the length of the increased high-temperature flue gas area is equivalent to that of the low-temperature flue gas area, the low-temperature flue gas area accounts for 40-43% of the total length of the sintering machine, and the increased high-temperature flue gas area accounts for 42-45% of the total length of the sintering machine.
12. The sintering process based on coupled flue gas pollutant reduction by sintering flue gas mass-divided circulation according to claim 11, wherein the thickness of the sintering material layer is reduced by 5-10%, or the traveling speed of the sintering machine trolley is reduced by 5-10%.
13. A sintering process based on emission reduction of smoke pollutants generated by mass-separation cyclic coupling of sintering smoke comprises a sintering machine and a trolley thereof, a sintering airflow, sintering smoke formed after combustion-supporting sintering, a sintering mixture and sintering ore formed after sintering; the sintering airflow enters a sintering mixture layer to support combustion and sinter to form sintering flue gas under the suction action of a fan, and the sintering flue gas passes through the sintering mixture layer, a sintering machine trolley grate and an air box below the trolley to enter a main flue, the sintering mixture is sintered at high temperature to form sintering ore under the combustion support of the sintering airflow, and the sintering ore is discharged into a sintering ore cooling furnace along with the trolley at a fixed bend at the tail of the sintering machine; dividing the sintering machine into an ignition area, a low-temperature flue gas area and an SO area along the traveling direction of a trolley of the sintering machine 2 Region of rapid rise in concentration, SO 2 5 areas of a rapid concentration reduction area and a high-temperature flue gas area, and is characterized in that the sintering flue gas is collected through a low-temperature flue gas main flue and a high-temperature flue gas main flue respectively; the low-temperature flue gas main flue collects sintering flue gas in an ignition area, the low-temperature flue gas area is close to the low-temperature sintering flue gas in the length range of 60-70% of the ignition area, and the high-temperature flue gas main flue collects a high-temperature flue gas area and SO 2 Region of rapidly decreasing concentration, SO 2 Sintering flue gas in a region with rapidly increased concentration and a region with low temperature flue gas close to SO 2 Low-temperature sintering flue gas with the concentration rapidly increasing area within the length range of 30-40%; the sintering flue gas in the low-temperature flue gas main flue enters the sinter cooling furnace from a cooling gas inlet of the sinter cooling furnace after being desulfurized by excessive ammonia water sprayed into the bellows; the sintering flue gas in the high-temperature flue gas main flue is mixed with oxygen and then enters a low-temperature flue gas area and SO 2 The concentration is quickly increased in the high-temperature flue gas circulation cover above the sinter bed, and under the suction action of the fan, the flue gas enters the sinter bed again to be used as combustion-supporting air to participate in sintering.
14. The sintering process based on coupling of flue gas pollutant reduction by sintering flue gas mass-divided cycle according to claim 13, wherein the low temperature flue gas region and SO 2 2-4 groups of air box smoke outlets at the junction of the areas with the rapidly increased concentration are respectively connected with a low-temperature smoke main flue and a high-temperature smoke main flue through exchange valves.
15. The sintering process based on coupling of flue gas pollutant reduction by sintering flue gas mass-separation cycle according to claim 13, wherein the high temperature flue gas circulation hood covers the entire low temperature flue gas area and SO 2 A region of rapidly increasing concentration.
16. The sintering process based on coupling of flue gas pollutant reduction by sintering flue gas mass-divided circulation and emission reduction according to claim 13, wherein hot sinter in-furnace flue dust at the top of the sinter cooling furnace is introduced into SO 2 Concentration ofAnd under the suction action of a fan, the low-temperature flue gas enters the sinter bed to be used as combustion-supporting air to participate in sintering in the low-temperature flue gas circulation cover above the sinter bed in the rapid reduction area and the high-temperature flue gas area.
17. The sintering process based on emission reduction of pollutants from flue gas by mass-circulation coupling of sintering flue gas as claimed in claim 1 or 13, wherein the trolley and the sintering mixture run obliquely upwards from the head to the tail, and the sintering gas flow and the sintering flame front are perpendicular to the travelling direction of the trolley and obliquely downwards pass through the sintering material layer.
18. The sintering process based on emission reduction of flue gas pollutants from mass-separation cycle coupling of sintering flue gas as claimed in claim 1 or 13, wherein the trolley and the sintering mixture on the trolley run obliquely upwards from the head to the tail, and the inclination is 5-15%.
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| CN113551525B (en) * | 2021-07-01 | 2023-04-28 | 武汉科技大学 | Integrated sintering flue gas external circulation system |
| CN113828133B (en) * | 2021-08-27 | 2022-06-28 | 上海交通大学 | Iron ore sintering flue gas multi-pollutant coprocessing device |
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