CN217068340U - Ultralow emission device of sintered pellet flue gas - Google Patents
Ultralow emission device of sintered pellet flue gas Download PDFInfo
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- CN217068340U CN217068340U CN202122877161.7U CN202122877161U CN217068340U CN 217068340 U CN217068340 U CN 217068340U CN 202122877161 U CN202122877161 U CN 202122877161U CN 217068340 U CN217068340 U CN 217068340U
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Abstract
The utility model relates to an ultralow emission device of sintered pellet flue gas, which adopts a MGGH heat collector, a limestone-gypsum desulfurization tower, a wet electrostatic dust collector, a flue gas condensation deacidifier, a MGGH heater, a GGH, a direct combustion type burner and a SCR denitration process device; the utility model arranges a tray and a flow guide ring in the desulfurizing tower to uniformly distribute the flue gas, thereby improving the desulfurizing efficiency and removing a large amount of sulfur dioxide and dust; a set of flue gas acid-removing demister system is arranged at the outlet section of the wet electric precipitator, the temperature of the flue gas is reduced by more than 4 ℃, and the sulfuric acid mist in the flue gas is condensed and separated out, so that a large amount of sulfuric acid mist and other salt substances are removed, and the system equipment blockage caused by substances such as acid mist and the like of subsequent equipment is prevented; the utility model discloses well deNOx systems adopts built-in combustor to evenly arrange in the flue, and a small amount of sets more, the even gas consumption of practicing thrift of heating are equipped with static mixer to denitration reactor entry, ensure that ammonia-flue gas flow field is even, improve denitration efficiency.
Description
Technical Field
The utility model belongs to the technical field of the ultralow emission of atmospheric pollution control, especially relate to energy-concerving and environment-protective device is administered to iron and steel enterprise's flue gas.
Background
With the rapid development of economy in China, the yield of steel continuously rises, so that the pollution control of steel smoke gas is more and more severe, the emission index is more and more rigorous, and the sintered pellet smoke gas is the most important ring for the environmental-friendly and standard-reaching emission of steel enterprises. Since the 6 th month in 2017, the ecological environment ministry issued the emission standard of atmospheric pollutants for the steel sintering and pelletizing industry, the sintered pellet smoke of steel enterprises in various regions faces the problem of reaching the environmental standard, which brings huge economic impact and environmental technical challenge to the steel enterprises. Therefore, while the emission reaches the standard to the utmost extent, the aim of reducing the energy consumption as much as possible due to the environmental protection investment is also paid attention to, and the low-carbon high-efficiency process technology is required to treat the sintering pellet flue gas.
The treatment of the tail end of the flue gas of the sintered pellets is the most important link for finally realizing the emission of environmental protection up to the standard, and the technology is adopted for special purification equipment, such as a desulfurization tower, a denitration tower, an electric dust remover/a bag-type dust remover, a heat exchanger, a heater and the like which are matched in an auxiliary way. At present, most of the sintering pellet flue gas treatment technologies are process routes formed by combining the devices, the processes are relatively extensive combinations, the removal efficiency is low, the failure rate is high, certain waste of desulfurization and denitrification reactants, process water, coal gas and electric energy is caused, and how to achieve the low-carbon high-efficiency flue gas ultralow emission technology in the sintering pellet flue gas treatment process is the starting point of the invention.
Disclosure of Invention
The utility model provides a problem that exists for the above-mentioned technique of solving, provides a low carbon efficient sintered pellet flue gas minimum discharge device, optimizes, the design that becomes more meticulous to relevant clarification plant, realizes energy-concerving and environment-protective high efficiency, for the saving running cost of steel enterprise, accords with the low carbon environmental protection theory of advocating in china.
The utility model discloses use limestone-gypsum method desulfurization + wet-type electric precipitation + SCR denitration to explain for the process route, to the clarification plant design that becomes more meticulous, the utility model discloses the technique also can apply to other trades flue gas ultralow emission and administer.
The technical process route adopted by the utility model is as follows: sintered pellet flue gas → MGGH heat extractor → limestone-gypsum desulfurization tower → wet electrostatic precipitator → flue gas condensation deacidifier → MGGH heater → GGH raw flue gas side → SCR denitration system → GGH clean flue gas side → desulfurization and denitration induced draft fan → chimney discharge.
An ultralow emission device of sintered pellet flue gas comprises a desulfurization and dust removal system device and a denitration reaction system device; the desulfurization and dust removal system equipment comprises an MGGH heat extractor, a desulfurization tower, a wet electric dust remover, a flue gas acid and mist removal system and an MGGH heater; the denitration reaction system equipment comprises a rotary heat exchanger, a built-in burner, a static mixer, a denitration reactor and an induced draft fan; the flue gas sequentially passes through an MGGH heat extractor, a desulfurizing tower, a wet electric precipitator, an acid and mist removing device of a flue gas acid and mist removing system, an MGGH heater, a rotary heat exchanger, a built-in burner, a static mixer, a denitration reactor and an induced draft fan, and finally clean flue gas is led out by the induced draft fan to be sent to a chimney; an MGGH heat collector is arranged in front of an inlet of the desulfurizing tower, and heat of the raw flue gas is collected by using desalted water as a medium; the method is characterized in that: a tray, a first spraying layer, a first flow guide ring, a second spraying layer, a second flow guide ring, a third spraying layer and a demister are sequentially arranged in the desulfurizing tower from the flue gas inlet to the upper part; the wet electric dust remover adopts a flue gas upper-in and lower-out structure; the flue gas deacidification and demisting system comprises a deacidification demister, a cooling water station and a condensate water collecting tank, wherein a flue gas outlet of the wet electric precipitator is connected with a flue gas inlet of the deacidification demister, a condensate liquid port of the deacidification demister is connected with the condensate water collecting tank, the condensate water collecting tank is connected with a demister in a desulfurizing tower, the cooling water station provides cooling water for the deacidification demister, and a flue gas outlet of the deacidification demister is connected with a flue gas inlet of a MGGH heater; be equipped with the ammonia entry on the static mixer, the rectification grid is installed at the denitration reactor top, mixes the ammonia flue gas and passes through in the rectification grid gets into the denitration reactor.
The heat exchange elements of the MGGH heat collector and the MGGH heater are made of fluoroplastic PFA materials, the heat exchange tubes are light tubes, the specification size diameter is 10mm, and the thickness is 0.8 mm. The material is inert, has no requirements on smoke components and acid dew point temperature, is difficult to corrode, has smooth and small tension on the surface of the pipe, is difficult to scale and is easy to wash. The utility model provides a MGGH heat collector and MGGH heater, clean flue gas after the former flue gas heat heating desulfurization is removed dust can be fully utilized, the effect of flue gas whitening is played, the energy consumption is practiced thrift. The heat exchange element is made of fluoroplastic materials, the heat exchange tube is a light pipe, the specification size is 10mm multiplied by 0.8mm (thickness),
be equipped with three rows of abrasionproof pipes at MGGH heat extractor's windward side, the abrasionproof pipe material is PTFE, and the size is diameter 10mm, and thickness 1.0mm for intercept dust protection heat exchange tube prevents because the wearing and tearing of sintering pelletizing flue gas high degree of difficulty dust continuous scouring heat exchange tube. Meanwhile, the proper flow velocity between the tubes of the flue gas heat exchanger is selected, the tube spacing is 30mm multiplied by 20mm, and the average calculated flow velocity of the flue gas is controlled to be below 8 m/s.
The tray is arranged at a position 0.8-2m above the flue gas inlet of the desulfurizing tower, and the liquid-gas ratio can be increased by the tray. The tray is made of duplex stainless steel, the thickness is 2-4mm, and the aperture ratio is 30-45%; the flue gas uniform distribution effect can be achieved, and the desulfurization efficiency is improved. In addition, the sprayed slurry forms a liquid film on the tray, so that the absorption of sulfur dioxide is increased, Ca/S is reduced, the consumption of limestone and the power consumption of a circulating pump are saved, the dust removing capacity is improved, and particularly the removing efficiency of the ultrafine dust below PM2.5 can reach more than 70%. The flue gas upwards convects with the slurry of the spraying layers, and the flue gas on the wall of the desulfurization tower is converged to flow towards the center of the tower through the diversion rings between the spraying layers, so that the series flow short circuit of the flue gas is prevented.
The sizes of the two layers of guide rings are both circular rings with the projection length of 400mm, and the included angle between the two layers of guide rings and the wall of the desulfurizing tower is 60 degrees.
The wet-type electric dust collector is of an upper inlet and lower outlet structure type structure, so that the resistance of a flue can be reduced, and the occupied area is saved. The cathode wire of the wet electric dust collector adopts the rigid needling wire, the electric field near the plate wire is enhanced due to point discharge, dust accumulation is not easy to occur at needling points, ionization capacity is enhanced by utilizing the point discharge, a better non-uniform electric field is formed by utilizing the change of an angle, an ionization area is enlarged, and the capacity of the wet electric dust collector is effectively improved. The lower part is equipped with the water catch bowl, and the water catch bowl bottom is the ship type structure, can prevent that a large amount of sparge water from persisting when washing and influencing wet-type electrostatic precipitator work, is equipped with the wash port at the least significant end.
The flue gas deacidification demister is internally divided into two sections, namely a flue gas condensation deacidification section and a flue gas demister section, and is in a series connection mode, and the flue gas deacidification demister is a two-stage flat plate type and is provided with a flushing water valve and a pipeline.
The heat exchange tubes of the flue gas condensation deacidification section are vertically arranged in a U shape, the flue gas passes through the shell side, the distance between the heat exchange tubes is 22mm multiplied by 20mm, the flow velocity of the flue gas between the tubes is controlled to be 7.5m/s, the wet flue gas after desulfurization and dedusting can be effectively cooled and condensed, and substances such as sulfate, carbonate, acid mist and the like carried in the flue gas are effectively removed to prevent blockage.
And a water stop ring is arranged between the flue gas condensation deacidification section and the flue gas demister section, and the cross section of the water stop ring is a semicircular ring with the diameter of 200 mm.
The utility model discloses be provided with a condensate collecting pit for collect flue gas condenser exhaust condensate, and wash the water source as the desulfurizing tower defroster, establish process water supply pipeline and motorised valve all the way simultaneously in addition, the pond is equipped with the level gauge.
The outlet of the built-in combustor adopts a bell mouth type structure, and the sectional area ratio of the inlet to the outlet is 1: 4.
A high-temperature isolator is arranged 0.8-1.5 meters above the flame outlet of the built-in burner, and the high-temperature isolator is made of 310 stainless steel. Meanwhile, in order to reduce the temperature of the high-temperature isolator, a cold flue gas channel is created between the high-temperature isolator and the wall surface, a small amount of low-temperature flue gas is used for cooling the high-temperature isolator, and heat transfer from high-temperature heat to the wall surface is isolated, so that heat loss is reduced, and the gas consumption is reduced.
A high-temperature spoiler is arranged at 0.6-1m below the flame of the built-in burner and is made of 310 stainless steel. The function of the device is to quickly mix high-temperature flue gas generated by combustion and reduce the temperature to a set temperature. Through setting up the high temperature spoiler, make the low temperature flue gas fully wrap up the high temperature flue gas, mix, proportion 1: 20, the high-temperature area can be reduced, and the dosage of the high-temperature alloy can be reduced.
The modular ammonia injection grid is arranged in the X direction and the Y direction of an ammonia gas inlet of the static mixer, the size of each modular ammonia injection grid is 1m multiplied by 2m, 5 branch pipes are distributed, each branch pipe is provided with 5 nozzles, so that the nozzles of the modular ammonia injection grid are uniform when the section of a flue is initial, meanwhile, the modular ammonia injection grid is provided with any module in the section of the flue which can be independently adjusted, and the flue gas has an adjusting function in each part. The modular ammonia injection grid modules are connected in a socket joint mode, so that the modular ammonia injection grid has a quick assembly function, the expansion of the ammonia injection grid at high temperature is absorbed, and the welding amount of the ammonia injection grid is reduced.
A method for utilizing a sintering pellet flue gas ultralow emission device is characterized by comprising the following steps:
(1) raw flue gas at the temperature of 140-180 ℃ from sintering or untreated pellets enters an MGGH heat extractor, the temperature of the flue gas is reduced by 25 ℃ after the heat exchange between the flue gas and heat medium water, the obtained heat is transferred to a subsequent flue gas heater through the heat medium water, an anti-abrasion pipe of the MGGH heat extractor does not participate in the heat exchange, and the anti-abrasion pipe only serves as a function of protecting a heat exchange pipe from continuous scouring and abrasion of high-concentration dust of the flue gas. After cooling, the flue gas entering at the temperature of 115 ℃ and 125 ℃ enters a desulfurization tower;
(2) the flue gas enters the desulfurizing tower and then passes through the tray, the spraying layer and the flow guide ring between the spraying layers in sequence, and SO in the flue gas 2 And the dust is removed; the specific process comprises the following steps: cigarette with heating meansAfter the gas is uniformly distributed on the tray, the gas is fully contacted and absorbed with the slurry sprayed in the counter-current manner and the liquid film with the thickness of 2-3mm formed on the upper surface of the tray, and at the moment, more than 60 percent of SO is generated 2 80% of dust particles, especially ultrafine dust below PM2.5, are washed and removed, and then the flue gas passes through a spray layer and a guide ring to remove SO 2 Further removing, simultaneously preventing the phenomenon of flue gas channeling by utilizing the action of a flow guide ring, and ensuring SO 2 Removing, wherein the smoke finally passes through a demister at the upper part of the desulfurizing tower to remove fog drops, the temperature of the smoke is about 50 ℃, and SO is 2 The content is less than 30mg/Nm 3 Dust content of less than 20mg/Nm 3 ；
(3) The low-dust content flue gas enters the wet electric dust collector from the top of the desulfurizing tower and then flows out from the lower part of the desulfurizing tower, the dust in the flue gas is further removed, and the concentration of the dust in the flue gas is less than 5mg/Nm 3 60% of acid mist is driven to the wall of the anode tube after being charged, and liquid drops carrying dust and the acid mist fall into a ship-shaped liquid accumulation groove at the bottom after being washed and are discharged;
(4) the flue gas is desulfurized and dedusted, then enters a flue gas condensation and deacidification section of a flue gas deacidification and demister, more than 90% of acid mist and acid salt in the flue gas are condensed and separated out to form fog drops which are hung on the outer wall of a pipe, and after washing, the drops of the acid mist and the acid salt are collected into a condensed water collecting tank; the water collecting tank is provided with a process water supplementing pipeline, the process water is supplemented and mixed to be used as washing water of a demister of the desulfurizing tower, part of new water is saved, and water balance in the system is ensured; the water stop ring is arranged to prevent condensed water from being brought into the flue gas demister section along with flue gas, the flue gas enters the flue gas demisting section, a small amount of acid mist, acid salt and water mist generated in the washing process are removed again, the temperature of the flue gas is reduced to about 46 ℃, and the concentration of sulfuric acid mist in the flue gas is reduced to 20mg/Nm 3 The risk of blockage of subsequent equipment due to sulfuric acid mist is reduced;
(5) the flue gas subjected to acid and mist removal is sent to an MGGH heater, and a heat source of an MGGH heat collector is transferred through heat medium water, so that the temperature of the flue gas is increased to about 70 ℃ to form unsaturated flue gas, the white elimination of the flue gas is realized, and the gas consumption required by the subsequent temperature rise of the denitration flue gas is also saved;
(6) after the flue gas enters the rotary heat exchanger, the outlet temperature reaches about 260 ℃; the built-in burner of the upper flue is used for supplementing heat, the temperature is raised to be higher than 280 ℃, a high-temperature isolator is arranged in the flame area of the built-in burner, the phenomenon that the temperature of the wall surface is over-high due to the fact that high temperature is directly radiated to a flue wall plate is avoided, meanwhile, in order to reduce the temperature of the high-temperature isolator, a channel is created between the high-temperature isolator and the wall surface, low-temperature flue gas is used for cooling the high-temperature isolator, heat transfer of high-temperature heat to the wall surface is isolated, heat loss is reduced, and gas consumption is saved.
(7) The flue gas after temperature rise is fully mixed with ammonia gas under the disturbance of a static mixer, the mixture enters a denitration reactor after being rectified by a rectifying grid, ammonia and NOx in the flue gas are subjected to selective catalytic reduction reaction on the surface of a catalyst, the reacted clean flue gas is sent to a rotary heat exchanger through a denitration outlet flue, exchanges heat with the original flue gas for cooling, the temperature is reduced to about 110 ℃ after coming out of a cooling end of the rotary heat exchanger, and finally the flue gas is sent to a chimney by an induced draft fan for emission.
The process system can purify sulfur dioxide, nitrogen oxides and dust in the sintering pellet flue gas and save limestone, process water, fuel gas and electric energy. In addition, the method also considers the purification process to remove sulfate, carbonate, acid mist and the like, prevents equipment from being blocked, realizes the white elimination of the flue gas, eliminates visual pollution and creates a good enterprise image.
The utility model discloses to the characteristics of sintering pelletizing flue gas, application MGGH (heat collector) + lime stone-gypsum method desulfurizing tower + wet electrostatic precipitator + flue gas condensation deacidification ware + MGGH (heater) + rotary heat exchanger (GGH) + direct combustion formula combustor + SCR denitration technology not only gets rid of sulfur dioxide, nitrogen oxide and dust high-efficiently, but also practices thrift lime stone, process water, coal gas and power consumption. In the purification process, partial sulfate, carbonate, acid mist and the like are removed, the system equipment is prevented from being blocked, the operation and maintenance cost of enterprises is saved, in addition, the smoke whitening is realized, the method is a low-carbon and high-efficiency sintering pellet smoke ultralow emission technology, and has remarkable environmental benefit and social benefit.
Drawings
Fig. 1 is a schematic connection diagram of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying fig. 1 and the specific embodiments. Those skilled in the art will recognize that the invention may be practiced without one or more of the specific details.
As shown in fig. 1, the ultra-low emission device for flue gas of sintered pellets of the present invention comprises a desulfurization and dust removal system device and a denitration reaction system device; the desulfurization and dust removal system equipment comprises an MGGH heat extractor 1, a desulfurization tower 2, a wet electric dust remover 6, a flue gas acid and mist removal system and an MGGH heater 11; the denitration reaction system equipment comprises a rotary heat exchanger 12, a built-in combustor 13, a static mixer 14, a denitration reactor 16 and an induced draft fan 17; the flue gas sequentially passes through an MGGH heat extractor 1, a desulfurizing tower 2, a wet electric dust collector 6, an acid and mist removing device 7 of a flue gas acid and mist removing system, an MGGH heater 11, a rotary heat exchanger 12, a built-in combustor 13, a static mixer 14, a denitration reactor 16 and an induced draft fan 17, and finally, clean flue gas is led out by the induced draft fan 17 to be sent to a chimney; an MGGH heat collector 1 is arranged in front of an inlet of the desulfurizing tower, and heat of raw flue gas is collected by using desalted water as a medium; the method is characterized in that: a tray 3, a first spraying layer, a first flow guide ring 4, a second spraying layer, a second flow guide ring 4, a third spraying layer and a demister 5 are sequentially arranged in the desulfurizing tower 1 from the flue gas inlet upwards; the wet electric dust remover 6 adopts a flue gas upper-in and lower-out structure; the flue gas deacidification and demisting system comprises a deacidification demister 7, a cooling water station 10 and a condensate collecting tank 9, wherein a flue gas outlet of a wet electric precipitator 6 is connected with a flue gas inlet of the deacidification demister 7, a condensate port of the deacidification demister 7 is connected with the condensate collecting tank 9, the condensate collecting tank 9 is connected with a demister 5 in the desulfurizing tower 1, the cooling water station 10 provides cooling water for the deacidification demister 7, and a flue gas outlet of the deacidification demister 7 is connected with a flue gas inlet of an MGGH heater 11; be equipped with the ammonia entry on the static mixer 14, the 16 tops in denitration reactor are installed to rectification grid 15, and the mixed ammonia flue gas passes through in rectification grid 15 gets into denitration reactor 16.
The heat exchange elements of the MGGH heat collector 1 and the MGGH heater 11 are made of fluoroplastic PFA materials, the heat exchange tubes are light tubes, the specification size diameter is 10mm, and the thickness is 0.8 mm.
The windward side of the MGGH heat collector 1 is provided with three rows of anti-abrasion pipes, the anti-abrasion pipes are made of PTFE, the size of the anti-abrasion pipes is 10mm, and the thickness of the anti-abrasion pipes is 1.0 mm.
The tray 3 is arranged at a position 0.8-2m above the flue gas inlet of the desulfurizing tower 2, the tray is made of duplex stainless steel, the thickness is 2-4mm, and the aperture ratio is 30-45%.
The two layers of guide rings 4 are circular rings with projection length of 400mm, and the included angle between the two layers of guide rings and the wall of the desulfurizing tower is 60 degrees.
The cathode wire of the wet electric dust collector 6 is a rigid needling wire, the lower part of the cathode wire is provided with a water collecting tank, the bottom of the water collecting tank is of a ship-shaped structure, and the lowest end of the water collecting tank is provided with a drain hole.
The flue gas deacidification demister 7 is internally divided into two sections, namely a flue gas condensation deacidification section and a flue gas demister section, and is in a series connection mode, and the flue gas deacidification demister is a two-stage flat plate type and is provided with a flushing water valve and a pipeline.
The heat exchange tubes of the flue gas condensation deacidification section are vertically arranged in a U shape, the flue gas passes through the shell side, the space between the heat exchange tubes is 22mm multiplied by 20mm, and the flow velocity of the flue gas between the tubes is controlled to be 7.5 m/s.
And a water stop ring 8 is arranged between the flue gas condensation deacidification section and the flue gas demister section, and the cross section of the water stop ring 8 is a semicircular ring with the diameter of 200 mm.
The outlet of the built-in combustor adopts a bell mouth type structure, and the ratio of the sectional areas of the inlet and the outlet is 1: 4.
A high-temperature isolator is arranged 0.8-1.5 meters above the flame outlet of the built-in burner, and the high-temperature isolator is made of 310 stainless steel. High temperature breaker structures are available.
A high-temperature spoiler is arranged at 0.6-1m below the flame of the built-in burner and is made of 310 stainless steel. High temperature turbulator structures are available.
Modular ammonia injection grids are arranged in the X and Y directions of an ammonia gas inlet of the static mixer 14, the size of each modular ammonia injection grid is 1m multiplied by 2m, 5 branch pipes are distributed, and each branch pipe is provided with 5 nozzles; the modular ammonia injection grid modules are connected in a socket joint mode.
The utility model relates to a method for utilizing an ultralow emission device of sintered pellet flue gas, which is characterized by comprising the following steps:
the high temperature and high dust flue gas from sintering/pelletizing passes through MGGH heat extractor 1 first for obtain the heat of former flue gas, and the flue gas gets into tray 3, water conservancy diversion ring 4, spray zone and defroster 5 in desulfurizing tower 2 in proper order afterwards, and the flue gas after the desulfurization dust removal in the desulfurizing tower gets into wet-type electrostatic precipitator 6 from the desulfurizing tower export, carries out further purification dust removal.
The flue gas from the wet electric precipitator enters a flue gas deacidification demister 7, heat exchange is carried out between circulating water and the flue gas through a circulating cooling water station 10, the flue gas is condensed by 4-5 ℃ in a condensation deacidification section, the moisture content of the flue gas is reduced, and most of acid mist and acid salt in the flue gas are separated out. The separated acid salt is collected into the condensate collecting tank 9 by the washing water through self-flowing or washing. And a water stop ring 8 is arranged between the deacidification section and the demisting section, so that separated acid salt and condensed water can be prevented from being brought into the flue gas deacidification demister 7. The flue gas containing a large amount of fog drops is washed by the flue gas and then enters a flue demisting section to remove the water vapor carried by the flue gas condensation and washing. In order to save water, a process water replenishing pipeline is arranged in the condensate collecting tank 9, and condensed and recovered water is mixed and conveyed to a demister 5 of the desulfurizing tower to be used as washing water.
The flue gas after the acid and mist removal of the sintering flue gas is sent to an MGGH heater 11 for temperature rise, and the heat source for temperature rise is obtained by the sintering raw flue gas through an MGGH heat collector 1. The flue gas is heated to about 25 ℃ and enters a rotary GGH heat exchanger. The flue gas is subjected to heat exchange with denitrated clean flue gas through a rotary heat exchanger 12, the temperature of the flue gas is raised to about 260 ℃ after the flue gas is discharged from a temperature rise section of the rotary heat exchanger 12, the flue gas is continuously heated to a temperature higher than 280 ℃ through a direct combustion heater 13, ammonia gas is fully mixed with the flue gas under the disturbance of a static mixer 14, the flue gas enters a denitration reactor 16 after passing through a rectifying grid 15, the ammonia and NOx in the flue gas are subjected to selective catalytic reduction reaction on the surface of a catalyst, the reacted clean flue gas is conveyed to the rotary heat exchanger 12 through a denitration outlet flue, is subjected to heat exchange with the original flue gas for cooling, is cooled to about 110 ℃ after being discharged from a cooling end of the rotary heat exchanger 12, and is finally conveyed to a chimney through an induced draft fan 17 for emission.
The examples illustrate that:
for example, a 450m 2 Sintering machine, flue gas amount is 1320000Nm 3 H, corresponding working condition flow 2527763m 3 The temperature of the flue gas is 145 ℃, and the concentration of sulfur dioxide is 3000mg/Nm 3 Nitrogen oxide concentration 350mg/Nm 3 Dust concentration 80mg/Nm 3 Concentration of sulfuric acid mist 300mg/Nm 3 The low-carbon high-efficiency sintering flue gas ultralow emission technology is adopted.
The flue gas treatment process comprises the following steps: the flue gas firstly enters the MGGH heat extractor 1, the temperature of the flue gas is reduced from 145 ℃ to 120 ℃, and the heat of the temperature reduction is transferred to the heat medium circulating water. Then the flue gas enters a desulfurizing tower 2, and the working condition flow of the flue gas is 2527763m due to temperature reduction 3 H was changed to 2392884m 3 And h, calculated according to the diameter of the desulfurizing tower of 14.5m, the flow velocity of the empty tower before cooling is 4.25m/s, the space velocity of the flue gas in the desulfurizing tower after cooling is 4.02m/s, which is reduced by about 5 percent compared with the space velocity, and the flue gas resistance is reduced by about 80Pa compared with the traditional method without an MGGH heat collector due to low flow velocity, so that the power consumption of a fan can be saved by 70kW/h according to the calculation.
The flue gas passes through the tray 3, the guide ring 4 and the spray layer in the desulfurizing tower 2 to circularly absorb and remove the sulfur dioxide with high efficiency under the action of the demister 5, the removal rate is more than 99 percent, and the concentration is from 3000mg/Nm 3 Removing to 30mg/Nm 3 The following. The dust content is controlled to be 80mg/Nm due to the synergistic effect of spraying, washing and the tray 3 for removing dust 3 Down to 30mg/Nm 3 And the sulfuric acid mist concentration removal efficiency is about 50%. The temperature of the flue gas at the outlet of the desulfurizing tower is 51 ℃, and the humidity is 14.7%. In the process, the Ca/S can reach 1.02, and 78kg/h of limestone is saved. The temperature of the flue gas is reduced by 25 ℃ by the heat collector 1, so that the water quantity taken away by heat evaporation is reduced by about 23 t/h.
The flue gas after desulfurization, preliminary dust removal and deacidification enters the wet electric precipitator 6 from the top for further dust removal, the design flue gas flow rate of the wet electric precipitator is 2m/s, most of dust in the flue gas is removed in the process, and the outlet dust of the wet electric precipitator is less than 5mg/Nm 3 The removal rate was 83.33%. Meanwhile, a small amount of sulfuric acid mist and salt substances are charged and then driven to the wall of the anode pipe of the wet electric dust collector and finally are subjected to gravity or impactAnd (5) washing and removing.
The flue gas enters an acid removal demister 7 after coming out from the side surface of the lower part of the wet electric precipitator, the flue gas is condensed to remove acid through heat exchange between cooling water from a circulating cooling water station 9 and the flue gas, the temperature of the flue gas is reduced by 4 ℃, namely the outlet temperature is 46 ℃, 30t/h of condensed water is separated out, meanwhile, acid mist in the flue gas is also separated out, and 80% of acid mist and salt substances are removed. The condensed water is collected into a condensed water collecting tank 8, and the new water is supplemented to be used as washing water of a demister of the desulfurizing tower for recycling, so that the new water is saved by 30 t/h. When the flue gas passes through the demisting section, the content of liquid drops at the flue gas outlet is less than 20mg/Nm 3 The acid mist content is less than 20mg/Nm 3 。
The flue gas enters the MGGH heater 11, heat exchange is carried out between the flue gas and the heat medium water, the temperature of the flue gas is increased by about 25 ℃, namely the outlet temperature of the MGGH heater is 71 ℃, the flue gas is unsaturated flue gas, and therefore white smoke elimination is achieved. The process utilizes the heat of the original flue gas, which is equivalent to saving 13000m of blast furnace gas consumption 3 /h。
The flue gas after temperature rise enters a rotary GGH heat exchanger 12 to exchange heat with the denitrated clean flue gas, the flue gas is heated to about 260 ℃ after coming out of the GGH temperature rise section, and then the flue gas is continuously heated to more than 280 ℃ through a direct-fired heater 13. The burners are uniformly arranged in the flue, the number of the burners is 4, and a high-temperature turbulence device is arranged at 0.6-1m below the flame of the burner and is made of 310 stainless steel. The function of the device is to quickly mix high-temperature flue gas generated by combustion and reduce the temperature to a set temperature. Through setting up high temperature vortex device, make the low temperature flue gas fully with high temperature flue gas parcel, mix, reduce high temperature region and reduce about 1.5t of high temperature alloy quantity. Because the combustor is arranged in the flue, the heat dissipation is completely used for heating the flue gas, and the heat loss is small. A large amount of CO is burnt in the flue, so that the consumption of the blast furnace gas is reduced, the gas amount is comprehensively saved by 10 percent, namely, the consumption of the blast furnace gas is saved by about 2500m 3 /h。
The flue gas continues to upwards and the ammonia gas are fully mixed with the flue gas under the disturbance of the modular ammonia injection grid 14, the excessive waste of the ammonia is reduced, and the escape of the ammonia is controlled to be less than 2 ppm. The flue gas enters a denitration reactor 16 after passing through a rectifying grid 15, ammonia and NOx in the flue gas are subjected to selective catalytic reduction reaction on the surface of a catalyst, the reacted clean flue gas is sent to a rotary heat exchanger 12 through a denitration outlet flue, is subjected to heat exchange with the original flue gas for cooling, is discharged from a GGH cooling end and is cooled to about 110 ℃, and is finally sent to a chimney through an induced draft fan 17 for emission.
Claims (9)
1. An ultralow emission device of sintered pellet flue gas comprises a desulfurization and dust removal system device and a denitration reaction system device; the desulfurization and dust removal system equipment comprises an MGGH heat extractor, a desulfurization tower, a wet electric dust remover, a flue gas acid and mist removal system and an MGGH heater; the denitration reaction system equipment comprises a rotary heat exchanger, a built-in burner, a static mixer, a denitration reactor and an induced draft fan; the flue gas sequentially passes through an MGGH heat extractor, a desulfurizing tower, a wet electric precipitator, an acid and mist removing device of a flue gas acid and mist removing system, an MGGH heater, a rotary heat exchanger, a built-in burner, a static mixer, a denitration reactor and an induced draft fan, and finally, clean flue gas is led out by the induced draft fan to be sent to a chimney; an MGGH heat collector is arranged in front of an inlet of the desulfurizing tower, and heat of the raw flue gas is collected by using desalted water as a medium; the method is characterized in that: a tray, a first spraying layer, a first flow guide ring, a second spraying layer, a second flow guide ring, a third spraying layer and a demister are sequentially arranged in the desulfurizing tower from the flue gas inlet to the top; the wet electric dust remover adopts a flue gas upper-in and lower-out structure; the flue gas deacidification and demisting system comprises a deacidification demister, a cooling water station and a condensate collecting tank, wherein a flue gas outlet of the wet electric precipitator is connected with a flue gas inlet of the deacidification demister, a condensate port of the deacidification demister is connected with the condensate collecting tank, the condensate collecting tank is connected with a demister in a desulfurizing tower, the cooling water station provides cooling water for the deacidification demister, and a flue gas outlet of the deacidification demister is connected with a flue gas inlet of an MGGH heater; be equipped with the ammonia entry on the static mixer, the rectification grid is installed at denitration reactor top, and the mixed ammonia flue gas passes through in the rectification grid gets into denitration reactor.
2. The ultra-low emission flue gas device for sintered pellets of claim 1, wherein: the heat exchange elements of the MGGH heat collector and the MGGH heater are made of fluoroplastic PFA materials, the heat exchange tubes are light tubes, the specification size diameter phi is 10mm, and the thickness is 0.8 mm.
3. The ultra-low emission flue gas device for sintered pellets of claim 2, wherein: the windward side of the MGGH heat collector is provided with three rows of anti-abrasion pipes, the anti-abrasion pipes are made of PTFE, the size of the anti-abrasion pipes is 10mm, and the thickness of the anti-abrasion pipes is 1.0 mm.
4. The ultra-low emission flue gas device for sintered pellets of claim 1, wherein: the tray is arranged 0.8-2m above the flue gas inlet of the desulfurizing tower, the tray is made of duplex stainless steel, the thickness is 2-4mm, and the aperture ratio is 30-45%.
5. The ultra-low emission flue gas device for sintered pellets of claim 1, wherein: the sizes of the two layers of guide rings are both circular rings with the projection length of 400mm, and the included angle between the two layers of guide rings and the wall of the desulfurizing tower is 60 degrees.
6. The ultra-low emission flue gas device for sintered pellets of claim 1, wherein: the cathode wire of the wet electric dust collector adopts a rigid needling wire, the lower part of the cathode wire is provided with a water collecting tank, the bottom of the water collecting tank is of a ship-shaped structure, and the lowest end of the water collecting tank is provided with a drain hole.
7. The ultra-low emission flue gas device for sintered pellets of claim 1, wherein: the flue gas deacidification demister is internally divided into two sections, namely a flue gas condensation deacidification section and a flue gas demister section, which are connected in series, and the flue gas deacidification demister is a two-stage flat plate type and is provided with a flushing water valve and a pipeline; the heat exchange tubes of the flue gas condensation deacidification section are vertically arranged in a U shape, the flue gas passes through the shell pass, the space between the heat exchange tubes is 22mm multiplied by 20mm, and the flow velocity of the flue gas between the tubes is controlled to be 7.5 m/s; and a water stop ring is arranged between the flue gas condensation deacidification section and the flue gas demister section, and the cross section of the water stop ring is a semicircular ring with the diameter of 200 mm.
8. The ultra-low emission flue gas device for sintered pellets of claim 1, wherein: the outlet of the built-in combustor adopts a bell mouth structure, and the sectional area ratio of the inlet to the outlet is 1: 4; a high-temperature isolator is arranged 0.8-1.5 meters above the flame outlet of the built-in burner, and the high-temperature isolator is made of 310 stainless steel; a high-temperature spoiler is arranged at 0.6-1m below the flame of the built-in burner and is made of 310 stainless steel.
9. The ultra-low emission flue gas device for sintered pellets of claim 1, wherein: modular ammonia injection grids are arranged in the X direction and the Y direction of an ammonia gas inlet of the static mixer, the size of each modular ammonia injection grid is 1m multiplied by 2m, 5 branch pipes are distributed, and each branch pipe is provided with 5 nozzles; the modular ammonia injection grid modules are connected in a socket joint mode.
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