CN212609638U - Steel plant desulfurization waste water resourceful zero discharge system - Google Patents
Steel plant desulfurization waste water resourceful zero discharge system Download PDFInfo
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Abstract
The utility model discloses a desulfurization waste water resourceful zero discharge system of steel plant, include: the multi-effect evaporation unit is used for carrying out multi-effect forced circulation evaporation concentration treatment on the desulfurization wastewater of the iron and steel plant; the pH adjusting unit is used for adjusting the pH value of the first concentrated water output by the multi-effect evaporation unit; the bypass flue drying unit is used for carrying out atomization drying treatment on the first concentrated water after the pH value is adjusted; and the desulfurization and denitrification unit is used for providing high-temperature flue gas to the bypass flue drying unit and receiving the ammonia-containing mixed flue gas from the atomization drying treatment. The utility model discloses can effectively avoid the system scale deposit, need not additionally to increase the ammonia nitrogen that waste water removes ammonia nitrogen equipment and in the waste water and can effectively retrieve.
Description
Technical Field
The utility model relates to a technical field of steel plant desulfurization waste water treatment, more specifically say, relate to a steel plant desulfurization waste water resourceful zero discharge system.
Background
The iron and steel enterprises are water consumers in industrial enterprises, and although the repeated utilization rate of water of key iron and steel enterprises in China reaches more than 96%, a large amount of sewage and wastewater is discharged. According to the requirements of a new 'discharge Standard for Water pollution of iron and Steel industry' (GB13456-2012), from 1 month and 1 day of 2015, the existing enterprises execute the water pollution discharge limit value of the Standard 2, and the wastewater discharge amount of the iron and Steel works is from 2.0m3The t (crude steel) is reduced to 1.8m3The requirements of a plurality of indexes of the water quality of the discharged water are further improved. In addition, as the shortage of water resources in China is increased, many steel enterprises are faced with the situation that the supply of external water resources is increasingly short. Therefore, the method further improves the wastewater reuse rate of iron and steel enterprises, gradually realizes zero discharge of wastewater, and is an important task facing the iron and steel industry.
The limestone-gypsum method desulfurization process is widely used in steel plants, and a certain amount of desulfurization waste water must be discharged from the system in order to maintain the balance of materials in a slurry circulation system of a desulfurization device, prevent the concentration of soluble chloride ions in flue gas from exceeding a specified value, and ensure the quality of gypsum. The desulfurization waste water concentration is high, and the composition is complicated, and the salinity of waste water can not be handled to traditional triplex case, if the triplex case goes out the direct discharge and will cause very big harm to the environment. With the increasing of the environmental protection requirement, the realization of zero emission of the desulfurization wastewater of the steel plant is imperative.
The concentration of salt in the desulfurization waste water of the steel plant is very high (TDS: 30000-4+: 500-2000 mg/L), contains various heavy metal ions and has high hardness, CaSO4Tends to be saturated, belongs to typical high-salt wastewater which is difficult to treat and is difficult to treat by the traditional water treatment technology.
At present, the research on zero emission of the desulfurization wastewater of the steel plant is still in the initial stage. The desulfurization wastewater of the steel plant has the commonness of the desulfurization wastewater of the limestone-gypsum method, and has high ammonia nitrogen content, and needs special treatment. The treatment method of the high ammonia nitrogen wastewater mainly comprises a biological denitrification technology and a physical and chemical treatment technology, the salt concentration of the desulfurization wastewater is very high, and the biological denitrification technology is not suitable; the physical and chemical treatment technologies mainly include stripping, ion exchange, breakpoint chlorination, precipitation, membrane separation and the like, and the use of these methods all requires a large increase in investment cost and operation cost.
Disclosure of Invention
To the problem that exists among the prior art, the utility model provides a system suitable for high ammonia nitrogen desulfurization waste water treatment of steel plant and can realize desulfurization waste water zero release.
The utility model provides a zero discharge system of steel plant desulfurization waste water resourceization, the system includes:
the multi-effect evaporation unit is used for carrying out multi-effect forced circulation evaporation concentration treatment on the desulfurization wastewater of the iron and steel plant;
the concentrated water unit is used for adjusting the pH value of the first concentrated water output by the multi-effect evaporation unit;
the bypass flue drying unit is used for carrying out atomization drying treatment on the first concentrated water after the pH value is adjusted;
and the desulfurization and denitrification unit is used for providing high-temperature flue gas to the bypass flue drying unit and receiving the ammonia-containing mixed flue gas from the atomization drying treatment.
According to the utility model discloses an embodiment of steel plant desulfurization waste water resourceful zero discharge system, two to four effects circulation evaporation plant and condensing equipment, distilled water storage container and the vacuum pump that the multiple-effect evaporation unit includes series connection, condensing equipment links to each other with last effect circulation evaporation plant's steam outlet, and the vacuum pump links to each other with condensing equipment, and each effect circulation evaporation plant's distilled water export and condensing equipment's distilled water export all links to each other with distilled water storage container.
According to the utility model discloses an embodiment of steel plant desulfurization waste water resourceful zero discharge system, the system is still including setting up at multiple-effect evaporation unit upper reaches and carrying out the preprocessing unit that the suspended solid got rid of the processing to steel plant desulfurization waste water, preprocessing unit is traditional three headers or coagulating sedimentation device.
According to the utility model discloses an embodiment of steel plant desulfurization waste water resourceful zero discharge system, dense water unit includes dense water storage container, dense water pump and adds the subunit, it links to each other with dense water storage container's dosing mouth to add the subunit, dense water pump links to each other with dense water storage container's dense water export.
According to the utility model discloses an embodiment of steel plant desulfurization waste water resourceful zero discharge system, bypass flue drying unit includes bypass flue drying device, first dust collector and booster fan, bypass flue drying device is high-speed rotatory spray drier or two fluid driers, bypass flue drying device's flue gas entry links to each other and the exhanst gas outlet passes through the flue gas extraction pipeline and links to each other with the desulfurization unit of SOx/NOx control unit and the exhanst gas outlet passes through the denitration subunit in flue gas conveying pipeline and SOx/NOx control unit and links to each other, wherein, be provided with first dust collector and booster fan on the flue gas conveying pipeline.
According to one embodiment of the recycling zero-discharge system for the desulfurization wastewater of the steel plant, the desulfurization and denitrification unit comprises a desulfurization subunit, a denitrification inlet flue gas heat exchange device, a denitrification subunit and a chimney, the desulfurization subunit comprises a sintering machine or a pellet line, a second dust removal device, a desulfurization booster fan and a desulfurization tower which are connected in sequence, the denitration subunit comprises an ammonia injection device, an SCR reaction device and a denitration booster fan which are connected in sequence, the flue gas outlet of the desulfurizing tower is connected with the flue gas inlet of the ammonia injection device through a denitration inlet flue gas heat exchange device, the flue gas outlet of the SCR reaction device is connected with a denitration booster fan and a chimney through a denitration inlet flue gas heat exchange device, and a flue gas extraction pipeline connected with the bypass flue drying unit is arranged between the denitration inlet flue gas heat exchange device and the ammonia injection device.
According to the utility model discloses an embodiment of steel plant desulfurization waste water resourceful zero discharge system, still be provided with between denitration entry flue gas heat transfer device and the ammonia injection apparatus and supply with fire the subunit, wherein, the high temperature flue gas returns after the front end extraction of supplementary firing subunit again and carries to the rear end of supplementary firing subunit or the high temperature flue gas returns after the rear end extraction of supplementary firing subunit again and carries to the rear end of supplementary firing subunit.
Compared with the conventional scheme, the utility model discloses carry out the zero release to steel plant desulfurization waste water and handle, provide a technology and system that can realize the zero release of desulfurization waste water, the system is simple moreover, take up an area of for a short time, the running cost is low, can effectively avoid the system scale deposit, need not additionally to increase the ammonia nitrogen that waste water removes ammonia nitrogen equipment and in the waste water and can effectively retrieve and carry out resourceization reuse.
Drawings
Fig. 1 shows a schematic structural diagram of a zero emission system for recycling desulfurization wastewater from a steel plant according to an exemplary embodiment of the present invention.
Fig. 2 shows the schematic structural diagram of the iron and steel plant desulfurization wastewater resource zero-discharge system in embodiment 1 of the present invention.
Fig. 3 shows the schematic structural diagram of the zero discharge system for recycling desulfurization wastewater of iron and steel plant in embodiment 2 of the present invention.
Description of reference numerals:
1-pretreatment unit, 2-multiple-effect evaporation unit, 21-first-effect circulating evaporation device, 211-evaporator, 212-heater, 213-circulating pump, 22-last-effect circulating evaporation device, 23-distilled water storage container, 24-condensing device, 25-vacuum pump, 3-concentrated water unit, 31-concentrated water storage container, 32-concentrated water pump, 4-bypass flue drying unit, 41-bypass flue drying device, 42-first dust removal device, 43-booster fan, 5-desulfurization and denitration unit, 51-sintering machine or pellet line, 52-second dust removal device, 53-desulfurization and booster fan, 54-desulfurization tower, 55-denitration inlet flue gas heat exchange device, 56-ammonia injection device, 57-SCR reaction device, 58-denitration booster fan, 59-chimney and 6-afterburning subunit.
Detailed Description
All of the features disclosed in this specification, or all of the steps in any method or process so disclosed, may be combined in any combination, except combinations of features and/or steps that are mutually exclusive.
Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. That is, unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features.
The design idea of the desulfurization wastewater recycling zero-emission system of the steel plant is explained below.
The utility model discloses actually adopted the technical route that multiple-effect evaporative concentration and bypass flue drying combined together, utilized the bypass flue to carry out the drying to the dense water of evaporative concentration gained, can effectively practice thrift the system energy and carry out recycle with steel plant desulfurization waste water, realized realizing the utilization of the resourceful of ammonia nitrogen in the desulfurization waste water when the waste water zero release.
Thus, the process may specifically include the following steps.
Step A:
the desulfurization wastewater of the steel plant is subjected to multi-effect forced circulation evaporation concentration treatment under an acidic condition to obtain first concentrated water. Wherein, the pH value of the desulfurization wastewater of the steel plant is detected, and the pH value of the desulfurization wastewater of the steel plant is adjusted to be below 6 and preferably to be about 6 under the acidic condition when needed. The adoption carries out the evaporative concentration under the acid condition partially, can prevent that the ammonia in the desulfurization waste water from escaping out, and the utility model discloses can adopt HCl as the pH regulator of adjusting acid condition.
The desulfurization wastewater of the steel plant treated by the utility model is sintering and pelletizing high ammonia nitrogen desulfurization wastewater of the steel plant adopting the limestone-gypsum desulfurization and SCR denitration process,specifically, the salt concentration TDS is 30000-60000mg/L, and NH4+The concentration is 500-2000 mg/L, the COD is 500-2500 mg/L, and Cl-The concentration is 5000-25000 mg/L, and the CaSO contains various heavy metal ions4High salinity wastewater which tends to be saturated.
Preferably, the method further comprises a pretreatment step of pretreating the desulfurization wastewater of the steel plant to reduce the concentration of suspended matters before the step A, wherein the pretreatment step is mainly to remove the suspended matters to achieve the effect of reducing the concentration, and can be carried out by adopting a traditional three-way box or a coagulating sedimentation device and reducing the concentration to below 500 mg/L.
The utility model discloses a concentrated processing of multiple-effect forced circulation evaporation can carry out the concentration and obtain distilled water and first dense water to desulfurization waste water, preferably adopts the seed crystal to prevent the evaporation pipeline scale deposit. The method is characterized in that calcium sulfate crystals are used as starting crystal seeds, calcium sulfate is an easily-scaling substance in the desulfurization wastewater, the concentration of the desulfurized wastewater tends to be saturated, and the like substances are used as the crystal seeds, so that newly-generated calcium sulfate crystals are easily adsorbed.
When the system is started, starting crystal seeds are added, and calcium sulfate crystals are newly generated in the desulfurization wastewater along with the proceeding of the evaporation and concentration process during normal operation, so that the system can maintain a certain amount of crystal seeds. And in the process of concentrating the desulfurization wastewater, newly-formed calcium sulfate crystals can be preferentially separated out on the surface of the crystal seeds, so that scaling on the inner wall of the heat exchange tube is avoided, and meanwhile, a high-flow circulating pump with the circulating flow rate of more than 2m/s can be adopted, and the scaling is further avoided through high-flow-rate scouring. Wherein, the addition amount of the starting seed crystal is controlled according to the amount of the incoming water, if the amount of the treated water is within 50t/h, the addition amount of the seed crystal is 10-100 kg, the evaporation efficiency is generally two-effect to four-effect, and the concentration multiple is 4-8 times.
The desulfurization wastewater of the steel plant is circularly evaporated and concentrated under the acidic condition, most of water resources are recycled (distilled water can be recycled), and the ammonia nitrogen in the wastewater is prevented from escaping to ensure the quality of product water and further recovery treatment.
And B:
and C, adjusting the first concentrated water obtained in the step A to be alkaline, and carrying out atomization drying treatment on the alkaline first concentrated water by using high-temperature flue gas to obtain ammonia-containing mixed flue gas for resource utilization.
Wherein, the pH value of the first concentrated water is preferably adjusted to be in alkalescence condition of more than 8 so as to be beneficial to the escape of ammonia, NaOH or lime can be used as the pH regulator for adjusting alkalinity in the step B, and the pH value adjustment can be realized by reasonably metering the NaOH or lime into the first concentrated water.
Then, the utilization flow is 40000-60000 Nm3And h, drying the atomized alkaline first concentrated water by using high-temperature flue gas at the temperature of 260-350 ℃, and removing dust to obtain ammonia-containing mixed flue gas and miscellaneous salts. The drying is complete drying, the adopted high-temperature flue gas is flue gas obtained after heat exchange is carried out on the flue gas at the desulfurization outlet, the obtained mixed flue gas containing ammonia is used as a denitration reducing agent and sent into the subsequent denitration step for denitration treatment, and the obtained miscellaneous salt is subjected to independent treatment or comprehensive resource treatment after being mixed with dedusting ash collected in other procedures, so that zero emission is realized. Preferably, the outlet temperature of the mixed flue gas containing ammonia gas is controlled to be above 5 ℃ higher than the acid dew point.
The ammonia nitrogen in the dried concentrated water forms ammonia gas to be mixed in the flue gas and form ammonia gas-containing mixed flue gas, and the cleaned flue gas after dust removal enters a subsequent denitration procedure, namely the ammonia nitrogen in the desulfurization wastewater of the steel plant is repeatedly used as a denitration reducing agent in the form of ammonia gas after being subjected to atomization drying 4, so that the consumption of the denitration reducing agent is reduced, the resource utilization of the ammonia nitrogen in the wastewater is realized, the overall flow is simple, the investment is saved, the occupied area is small, no scale is formed, and the operation cost is low.
The steel plant desulfurization wastewater resource zero-discharge system will be described in detail with reference to the accompanying drawings.
Fig. 1 shows a schematic structural diagram of a zero emission system for recycling desulfurization wastewater from a steel plant according to an exemplary embodiment of the present invention.
As shown in fig. 1, according to the exemplary embodiment of the present invention, the steel plant desulfurization wastewater recycling zero-emission system includes a multi-effect evaporation unit 2, a concentrated water unit 3, a bypass flue drying unit 4 and a desulfurization and denitrification unit 5. Wherein, multiple-effect evaporation unit 2 carries out multiple-effect forced circulation evaporation concentration to steel plant's desulfurization waste water, and dense water unit 3 carries out pH value regulation to the first dense water of multiple-effect evaporation unit 2 output, and bypass flue drying unit 4 carries out the atomizing drying to the first dense water after adjusting the pH value and handles, and SOx/NOx control unit 5 provides the high temperature flue gas and receives the mixed flue gas that contains ammonia after coming from the atomizing drying to bypass flue drying unit 4.
Preferably, the system also comprises a pretreatment unit 1 arranged at the upstream of the multi-effect evaporation unit 2, the pretreatment unit 1 can reduce the concentration of suspended matters in the wastewater by removing the suspended matters, the pretreatment unit 1 can be a traditional triple box or a coagulating sedimentation device, but can also directly carry out evaporation concentration treatment without carrying out sedimentation treatment, and the pretreatment unit 1 is determined by combining indexes of the desulfurization wastewater of the steel plant. After the desulfurization wastewater of the steel plant is pretreated by the pretreatment unit 1, the desulfurization wastewater can directly enter the multi-effect evaporation unit 2 for evaporation concentration treatment without chemical softening.
Specifically, the multi-effect evaporation unit 2 includes a two-to four-effect circulation evaporation device, and a condensation device 24, a distilled water storage container 23, and a vacuum pump 25 connected in series. The multi-effect evaporation unit 2 adopts a crystal seed method to prevent the system from scaling and adopts a forced circulation evaporation form, the evaporation efficiency is set according to the water quantity and the concentration requirement, and the effect is generally 2 to 4 for the desulfurization wastewater of the steel plant. Meanwhile, evaporation concentration is carried out under a slightly acidic condition to prevent ammonia in the wastewater from escaping.
In the multi-effect evaporation unit 2, the desulfurization wastewater of the steel plant firstly enters the first-effect evaporation device 21, and the wastewater is heated by steam in the heater 212 and then enters the evaporator 211 for flash evaporation. Part of water in the wastewater is flashed in the evaporator 211 to form secondary steam, which enters the next-effect evaporation and concentration device as a heat source of the next effect and is condensed into distilled water. The waste water is circulated and evaporated in the evaporative crystallization apparatus by the circulation pump 213. The secondary steam generated by the final-effect evaporation device 22 is condensed into distilled water in the condensing device 24, the residual non-condensable gas is discharged by the vacuum pump 25, and the condensing device 24 and the vacuum pump 25 can ensure that the whole system is in a micro-negative pressure state. After concentration, the distilled water is recycled to the distilled water storage container 23, and the part of the pure distilled water can be reused in the factory.
Adding a small amount of CaSO at the start-up of the multi-effect evaporation unit 24Seed crystal, CaSO newly generated in the process of evaporating and concentrating desulfurization waste water after adding seed crystal4Crystals are preferentially precipitated on the surface of the crystal seeds, so that the heat exchange tube is prevented from scaling and blocking. Meanwhile, a large-flow circulating pump 213 is adopted, the circulating flow rate is controlled to be more than 2m/s, and the scaling is further avoided through high-flow-rate scouring.
The concentrated water unit 3 includes a concentrated water storage container 31, a concentrated water pump 32, and a dosing subunit (not shown), the dosing subunit is connected to a dosing port of the concentrated water storage container 31, and the concentrated water pump 32 is connected to a concentrated water outlet of the concentrated water storage container 31. The first concentrate from the multi-effect evaporation unit 1 enters a concentrate storage container 31, the pH is adjusted in the concentrate storage container 31 to be more alkaline to facilitate the escape of ammonia in the subsequent process, and the alkaline first concentrate then enters the bypass flue drying unit 4 through a concentrate pump 32. Wherein, the dosing subunit stores and measures the pH regulator, and the pH regulator can adopt NaOH or lime, and a stirrer is preferably arranged in the concentrated water storage container 31 to improve the mixing efficiency.
The utility model discloses a bypass flue drying unit 4 includes bypass flue drying device 41, first dust collector 42 and booster fan 43, and bypass flue drying device 41 is high-speed rotatory spray drier or two fluid driers, and bypass flue drying device 41's flue gas entry links to each other through flue gas extraction pipeline and desulfurization unit of SOx/NOx control unit 5 and exhanst gas outlet passes through the flue gas conveying pipeline and links to each other with the denitration subunit in SOx/NOx control unit 5. The upper part of the bypass flue drying device 41 is provided with a concentrated water inlet and a flue gas inlet, and the lower part is provided with a material outlet and a flue gas outlet. The alkaline first concentrated water enters the dryer after being atomized by the high-speed rotary atomizer or the two-fluid spray gun in the bypass flue drying device 41, and meanwhile, the high-temperature flue gas is introduced into the bypass flue drying device 41 to completely dry the alkaline first concentrated water.
Wherein, the flue gas conveying pipeline is provided with a first dust removal device 42 and a booster fan 43, the temperature of the outlet of the bypass flue drying device 41 is preferably controlled to be higher than the acid dew point by more than 5 ℃, the dried miscellaneous salt enters the first dust removal device 42 (preferably a bag-type dust remover) along with the flue gas after drying, and the miscellaneous salt in the flue gas is collected after passing through the first dust removal device 42. The miscellaneous salts collected by the bottom of the bypass flue drying device 41 and the first dust removal device 42 can be collected and post-treated independently, and can also be uniformly mixed with the collected dedusting ash in the desulfurization and denitrification unit 5 for post-treatment, so that zero emission is realized.
According to the utility model discloses, SOx/NOx control unit 5 includes the SOx/NOx control subunit, denitration entry flue gas heat transfer device 55, denitration subunit and chimney 59, the SOx/NOx control subunit includes sintering machine or pelletizing line 51 that connects in order, second dust collector 52, desulfurization booster fan 53 and desulfurizing tower 54, the denitration subunit includes the ammonia injection apparatus 56 that connects in order, SCR reaction unit 57 and denitration booster fan 58, the exhanst gas outlet of desulfurizing tower 54 passes through denitration entry flue gas heat transfer device and links to each other with ammonia injection apparatus 56's flue gas entry, SCR reaction unit's exhanst gas outlet passes through denitration entry flue gas heat transfer device 55 and links to each other with denitration booster fan 58 and chimney 59. The denitration inlet flue gas heat exchange device 55 is mainly used for heat exchange between low-temperature flue gas discharged by the desulfurization subunit and high-temperature flue gas discharged by the denitration subunit, so that heat is recovered, and the gas consumption of the afterburning subunit is reduced.
Wherein, a flue gas extraction pipeline connected with the bypass flue drying unit 4 is arranged between the denitration inlet flue gas heat exchange device 55 and the ammonia injection device 56, and the flue gas extraction pipeline is directly connected with the flue gas inlet of the bypass flue drying device 41 of the bypass flue drying unit 4.
The ammonia nitrogen in the dried concentrated water forms ammonia gas to be mixed in the flue gas, the clean flue gas passes through the first dust removal device 42 and then enters the desulfurization and denitrification unit 5, particularly enters the SCR reaction device to be used as a denitrification reducing agent to be recycled, the consumption of the denitrification reducing agent is reduced, and the resource utilization of the ammonia nitrogen in the wastewater is realized.
Additionally, the utility model discloses can also be provided with after-combustion subunit 6 between denitration entry flue gas heat transfer device 55 and ammonia injection apparatus 56, then the heat source high temperature flue gas of bypass flue drying unit 4 can return again after the front end extraction of after-combustion subunit 6 and carry to the rear end of after-combustion subunit 6, perhaps returns again after the rear end extraction of after-combustion subunit 6 and carries to the rear end of after-combustion subunit 6, wherein front end and rear end define according to flue gas flow direction, the front end is the upper reaches that the flue gas flows promptly, the rear end is the low reaches that the flue gas flows. Because part of the hot flue gas is extracted, the load of the afterburning subunit 6 needs to be properly increased in order to ensure that the influence on the denitration system is reduced as much as possible. The afterburning subunit 6 is used for raising the temperature of the flue gas to the temperature required by the reaction of the denitration catalyst, and can be specifically set as a burner, and the coke oven gas or the blast furnace gas is combusted by the burner to increase the temperature of the flue gas.
The present invention will be further described with reference to the following specific embodiments.
Example 1:
the present embodiment adopts the system configuration shown in fig. 1.
As shown in FIG. 1, the amount of the desulfurization waste water of the iron and steel works in this example was 30m3And h, the ammonia nitrogen of raw water of the desulfurization wastewater of the steel plant is 1000mg/L, the concentration of chloride ions is 15000mg/L, and the temperature is 25 ℃.
The desulfurization wastewater of the steel plant firstly enters a pretreatment unit to remove suspended matters, the pH of the desulfurization wastewater is adjusted to be below 6 after the suspended matters are reduced to be below 500mg/L, and then the desulfurization wastewater enters a multi-effect evaporation unit 2 to be evaporated and concentrated by 6 times, wherein the water quantity of concentrated water is 5m3H, recovery gives 25m3The recovery rate of distilled water per hour reaches 83 percent. The multi-effect evaporation unit adopts 3-effect forced circulation evaporation to obtain CaSO4Preventing the system from scaling for the seed crystal. The heat exchange tube, the separation chamber, the pump, the pipeline and the contact part of the valve and the waste water in the multi-effect evaporation unit 2 are all made of 2205 or more anticorrosive materials.
The first concentrated water obtained by the multi-effect evaporation unit 2 enters a concentrated water storage container 31 in a concentrated water unit 3 to adjust the pH value to about 8, and then enters a bypass flue drying device 41 of a bypass flue drying unit 4, wherein the bypass flue drying device 41 uses stainless steel anticorrosive materials of 316L and above. The bypass flue drying device 41 adopts a high-speed rotary spray dryer, and concentrated water is sprayed into the bypass through a high-speed rotary atomizerFlue drying means 41. 60000Nm from before the ammonia injector3Introducing high-temperature flue gas with the temperature of about 260 ℃ per hour into a bypass flue drying device 41 to dry concentrated water.
The outlet temperature of the bypass flue drying device 41 is 142 ℃ (higher than the acid dew point by 5 ℃), the dried mixed salt enters the bag-type dust remover serving as the first dust removing device 42 along with the flue gas, and the dust content of the flue gas is reduced to 10mg/Nm after passing through the bag-type dust remover3The clean flue gas is then returned to the ammonia injector and into the denitration sub-unit. Ammonia nitrogen (about 30kg/h) in the desulfurization wastewater of the steel plant is dried and gasified and then is used as a denitration reducing agent, so that the use amount of the denitration reducing agent is reduced (144 kg/h is consumed by an original denitration system, and the consumption amount of the denitration reducing agent is reduced by 20.8%).
Example 2:
fig. 2 shows the schematic structural diagram of the iron and steel plant desulfurization wastewater recycling zero-emission system in embodiment 1 of the present invention, and the present embodiment adopts the system structure shown in fig. 2.
As shown in FIG. 2, the present embodiment is different from embodiment 1 in that an after-burning sub-unit 6 is further installed between the denitration inlet flue gas heat exchanging means 55 and the ammonia injection means 56, and 55000Nm is injected from the front end of the after-burning sub-unit 63Introducing high-temperature flue gas with the temperature of about 300 ℃ per hour into a bypass flue drying device 41 to dry concentrated water, introducing the dedusted ammonia-containing mixed flue gas into the rear end of the afterburning subunit 6, and introducing the dedusted ammonia-containing mixed flue gas into a denitration subunit to assist in denitration and then discharging.
Example 3:
fig. 3 shows the utility model discloses in embodiment 2 steel plant desulfurization waste water resource zero discharge system's schematic structure, this embodiment has adopted the system architecture that fig. 3 shows.
As shown in FIG. 3, the present embodiment is different from embodiment 1 in that an after-burning sub-unit 6 is further installed between the denitration inlet flue gas heat exchanging means 55 and the ammonia injection means 56, and 55000Nm is measured from the rear end of the after-burning sub-unit 63Introducing 300 ℃ high-temperature flue gas about/h into a bypass flue drying device 41 to dry concentrated water, introducing the dedusted ammonia-containing mixed flue gas into the rear end of the afterburning subunit 6 and then into a denitration subunitAnd (5) discharging after assisting in denitration.
The present invention is not limited to the foregoing embodiments. The invention extends to any novel feature or any novel combination of features disclosed in this specification, and to any novel method or process steps or any novel combination of features disclosed.
Claims (7)
1. The utility model provides a desulfurization waste water resource zero release system of steel plant which characterized in that, the system includes:
the multi-effect evaporation unit is used for carrying out multi-effect forced circulation evaporation concentration treatment on the desulfurization wastewater of the iron and steel plant;
the concentrated water unit is used for adjusting the pH value of the first concentrated water output by the multi-effect evaporation unit;
the bypass flue drying unit is used for carrying out atomization drying treatment on the first concentrated water after the pH value is adjusted;
and the desulfurization and denitrification unit is used for providing high-temperature flue gas to the bypass flue drying unit and receiving the ammonia-containing mixed flue gas from the atomization drying treatment.
2. The steel plant desulfurization wastewater resource zero-emission system as claimed in claim 1, wherein the multi-effect evaporation unit comprises two-to-four-effect cyclic evaporation devices, a condensing device, a distilled water storage container and a vacuum pump which are connected in series, the condensing device is connected with a steam outlet of the last-effect cyclic evaporation device, the vacuum pump is connected with the condensing device, and a distilled water outlet of each-effect cyclic evaporation device and a distilled water outlet of the condensing device are both connected with the distilled water storage container.
3. The steel plant desulfurization wastewater resource zero-emission system of claim 1, which is characterized in that the system further comprises a pretreatment unit which is arranged at the upstream of the multi-effect evaporation unit and is used for removing suspended matters from the desulfurization wastewater of the steel plant, and the pretreatment unit is a traditional triple box or a coagulation precipitation device.
4. The steel plant desulfurization wastewater resource zero-emission system as claimed in claim 1, wherein the concentrated water unit comprises a concentrated water storage container, a concentrated water pump and a dosing subunit, the dosing subunit is connected with a dosing port of the concentrated water storage container, and the concentrated water pump is connected with a concentrated water outlet of the concentrated water storage container.
5. The steel plant desulfurization wastewater resource zero-emission system of claim 1, wherein the bypass flue drying unit comprises a bypass flue drying device, a first dust removal device and a booster fan, the bypass flue drying device is a high-speed rotary spray dryer or a dual-fluid dryer, a flue gas inlet of the bypass flue drying device is connected with a desulfurization unit of a desulfurization and denitrification unit through a flue gas extraction pipeline, a flue gas outlet of the bypass flue drying device is connected with a denitrification subunit in the desulfurization and denitrification unit through a flue gas conveying pipeline, and the flue gas conveying pipeline is provided with the first dust removal device and the booster fan.
6. The steel plant desulfurization wastewater resource zero-emission system of claim 1, the desulfurization and denitrification unit comprises a desulfurization subunit, a denitrification inlet flue gas heat exchange device, a denitrification subunit and a chimney, the desulfurization subunit comprises a sintering machine or a pellet line, a second dust removal device, a desulfurization booster fan and a desulfurization tower which are connected in sequence, the denitration subunit comprises an ammonia injection device, an SCR reaction device and a denitration booster fan which are connected in sequence, the flue gas outlet of the desulfurizing tower is connected with the flue gas inlet of the ammonia injection device through a denitration inlet flue gas heat exchange device, the flue gas outlet of the SCR reaction device is connected with a denitration booster fan and a chimney through a denitration inlet flue gas heat exchange device, and a flue gas extraction pipeline connected with the bypass flue drying unit is arranged between the denitration inlet flue gas heat exchange device and the ammonia injection device.
7. The steel plant desulfurization wastewater resource zero-emission system of claim 6, wherein a post-combustion subunit is further arranged between the denitration inlet flue gas heat exchange device and the ammonia injection device, wherein the high-temperature flue gas is extracted from the front end of the post-combustion subunit and then returned to the rear end of the post-combustion subunit, or the high-temperature flue gas is extracted from the rear end of the post-combustion subunit and then returned to the rear end of the post-combustion subunit.
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