CN108328835A - A kind of desulfuration waste water treatment process - Google Patents
A kind of desulfuration waste water treatment process Download PDFInfo
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- CN108328835A CN108328835A CN201810172356.1A CN201810172356A CN108328835A CN 108328835 A CN108328835 A CN 108328835A CN 201810172356 A CN201810172356 A CN 201810172356A CN 108328835 A CN108328835 A CN 108328835A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/40—Magnesium sulfates
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/001—Processes for the treatment of water whereby the filtration technique is of importance
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/02—Treatment of water, waste water, or sewage by heating
- C02F1/04—Treatment of water, waste water, or sewage by heating by distillation or evaporation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/444—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by ultrafiltration or microfiltration
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/52—Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/101—Sulfur compounds
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2101/00—Nature of the contaminant
- C02F2101/10—Inorganic compounds
- C02F2101/20—Heavy metals or heavy metal compounds
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/18—Nature of the water, waste water, sewage or sludge to be treated from the purification of gaseous effluents
Abstract
The invention discloses a kind of desulfuration waste water treatment process, it is characterised in that：It comprises the technical steps that：Step 1, it pre-processes：Organic sulfur, carbonate and flocculant are added into desulfurization wastewater to be reacted, removes the calcium ion and heavy metal ion in desulfurization wastewater, obtains pretreatment fluid；Step 2, it is concentrated by evaporation：Pretreatment fluid is evaporated concentration, until it is 200 280mg/l to obtain in feed liquid sodium chloride content；Step 3, crystallisation by cooling：Slurry is obtained by crystallisation by cooling is carried out by the feed liquid being concentrated by evaporation, crystallization temperature is 20 DEG C hereinafter, crystallization time is 0.25 1h；Step 4, it centrifuges, is dry：Slurry after crystallisation by cooling is centrifuged and is dried, MgSO is obtained4•7H2O.The present invention will not introduce extra calcium ion in pretreatment, need not increase and the tedious steps that soda ash removes calcium ion are added, reduce the usage amount of reagent, and it is MgSO to finally obtain product4•7H2O improves the economic benefit of processing waster water process.
Description
Technical field
The present invention relates to a kind of waste water treatment process more particularly to a kind of desulfuration waste water treatment process.
Background technology
Coal-burning power plant is generated because of fire coal largely contains SO3Flue gas, the discharges of these flue gases can caused by Acid Rain Pollution pair
China crops, forest and health etc. cause huge damage.Therefore these flue gases cannot be directly discharged to air
In, it needs to handle these flue gases.
Common processing method is handled using Limestone-gypsum Wet Flue Gas Desulfurization Process, which comes
Water is discharged derived from absorption tower.The waste water of wet desulphurization contains a large amount of solid suspensions, supersaturated sulphite, sulfate, chlorination
Object and micro heavy, wherein many substances are to require the first pollutant strictly controlled in national environmental standard.According to
The regulation of DL/T 5196-2004 Coal,steam plant with FGD designing technique regulations is answered in the power plant for having desulfurization wastewater to generate
Desulfurization wastewater treatment system is separately provided, desulfurization wastewater has to pass through processing and could be discharged.
The desulfurization wastewater that wet desulphurization generates is mainly characterized in that salt content is very high, calcium ions and magnesium ions content is big, slant acidity, contains weight
Metal etc..Due to the calcium ions and magnesium ions of high-content, the hardness in desulfurization wastewater is high；And CaSO4 is in hypersaturated state so that desulfurization
Waste water is easy fouling in heating concentration process.
Power plant mainly adjusts pH value to desulfurization wastewater pretreatment, removes oil removal and heavy metal at present, wherein for demagging
Quick lime need to be added in ion, after introducing extra calcium ion, also need that soda ash removing calcium ion is added.This method not only complex steps,
It is also wasted very much in the use of reagent.
Pretreated desulfurization wastewater can recycle in flue gas desulphurization system, but increasing with cycle-index, take off
SO4 in sulphur waste water2-, Ca2+, Cl-Concentration accordingly increases, and therefore, pretreatment system need to discharge certain desulfurization wastewater to ensure
Desulfurization wastewater intermediate ion concentration is below saturation state.SO4 in the desulfurization wastewater discharged after pretreatment2-, Ca2+, Cl-Plasma
Content it is higher, the salinization of soil of water body and soil can be caused by being discharged into nature water environment.So desulfurization wastewater master after pre-processing at present
It is used for dry ash damping and coal yard water spraying, it to be the value for making flyash lose production building materials for dry ash damping to influence one, only
It can be used to repairing the roads or abandoning stacking, second is that for after coal yard water spraying, part chlorion is returned in slurries after burning, is caused
Desulphurization system discharges more desulfurization wastewaters, causes pollution source.
Currently, the method for carrying out in-depth processing for pretreated desulfurization wastewater is mainly the following：
The first：Reverse osmosis concentration method.This method need to locate water inlet in advance since film is to the particular/special requirement of influent quality
Reason, including turbidity, scale forming matter, COD etc., system complex, and recycle-water water quality inferiority, waste water cannot recycle completely, need to there is place
It receives.Equipment arrangement takes up a large area.
Second：Film mechanical recompression concentration method is rushed, currently, in the world using the producer of such processing method using two effects
Evaporation, i.e., the first effect are concentration effect, and the second effect is that crystallization and evaporation is imitated, and heat source is all used with electrically driven (operated) Mechanical Vapor Compression pressure
The indirect steam for this effect that contracts improves the quality recycling evaporation of indirect steam, can realize zero-emission substantially.
The third：Chemical tendering+multiple-effect evaporation, main problem existing for chemical tendering+multiple effective evaporation method are：Chemistry is soft
Waste water hardness after change is generally in 20~300mg/L（In terms of CaCO3）, with the progress of evaporation, the carbonate of calcium and magnesium ion,
Sulfate, phosphate etc. can gradually be precipitated in crystallization, and be attached on evaporation wall surface, will be formed in evaporator and pipe-line system
Serious fouling.According to practice, under this condition, evaporator is run 2~4 months, it is necessary to shut down snaking, cause production that cannot connect
Continuous property carries out；For multiple-effect evaporation compares single effect evaporation, steam consumption decreases, but as domestic steam price goes up,
System operation expense is still very high；Operational process needs to be continuously added live steam, does not have the enterprise of residue steam for some,
It also needs to additionally increase steam supply, increases project construction cost.
Publication No. CN101851041B, publication date are that on 2 8th, 2012 Chinese invention patents disclose a kind of desulfurization
The method and apparatus that zero-emission is realized in wastewater deepening processing.Described device includes sequentially connected liquid waste tank, preheater, degassing
Device, I effects evaporator, II effects evaporator, III effects evaporator, IV effects evaporator, centrifuge, batcher, vibra fluidized bed drying
Machine, intermediate bunker and packing machine.The method includes preheating desulfurization wastewater, deaerate；After level Four is evaporated be sent into centrifuge into
Row is separated by solid-liquid separation, dry.The invention device is simple, at low cost, but the invention adds calcium sulfate and chlorination in pretreatment
Calcium crystal seed, introduces calcium ion, after introducing extra calcium ion, leads to technique not only complex steps, in the use of reagent also very
Waste.
Publication No. CN105923822A, publication date, which has been the Chinese invention patent application on the 7th of September in 2016, discloses one
Kind desulfurization wastewater divides mud, divides salt technique of zero discharge, includes pretreating process, membrane treatment process and evaporative crystallization technique successively；
Desulfurization wastewater enters former pond in pretreating process, and Aeration fan is passed through compressed air into former pond, is then carried through raw water pump
First order reaction clarification is risen to, the desulfurization wastewater after three-level softening, clarification enters clear water reserviors, at a part of delivery film of clear water reserviors
Science and engineering process system, another part supply medicine system；Water enters back into pH adjustings after ultra-filtration filters first in membrane treatment process
Then case is pumped to nanofiltration film separation system and reverse osmosis membrane separation system；Evaporative crystallization technique water is preheated through two-stage first
Enter degasser afterwards, finally enters evaporation concentration system and crystal system.The production water of the technique can be used as industry water or boiler is mended
Water supply, by-product are recycled to greatest extent, reduce solid waste discharge, and by dividing mud, dividing salt, it is useless to reduce solid
Object disposal costs generate certain economic benefit by recycling by-product.But the technique adds milk of lime, it is same to introduce
Calcium ion and hydroxide ion lead to technique not only complex steps, are also wasted very much in the use of reagent.
Invention content
Technique caused by order to overcome the prior art to introduce extra calcium ion in processing desulfurization wastewater is cumbersome and reagent is unrestrained
The defect taken, the present invention provides a kind of desulfuration waste water treatment process, by the process desulfurization wastewater, not in pretreatment
Extra calcium ion can be introduced, need not increase and the tedious steps that soda ash removes calcium ion are added, reduce the usage amount of reagent, and
And it is MgSO to finally obtain product4•7H2O improves the economic benefit of processing waster water process.
In order to solve the above technical problems, the technical solution adopted in the present invention is：
A kind of desulfuration waste water treatment process, it is characterised in that：It comprises the technical steps that：
Step 1, it pre-processes
Organic sulfur is added into desulfurization wastewater, carbonate and flocculant are reacted, remove calcium ion in desulfurization wastewater and again
Metal ion obtains pretreatment fluid；
Step 2, it is concentrated by evaporation
Pretreatment fluid is evaporated concentration, until it is 200-280mg/l to obtain in feed liquid sodium chloride content；
Step 3, crystallisation by cooling
Slurry is obtained by crystallisation by cooling is carried out by the feed liquid being concentrated by evaporation, crystallization temperature is 20 DEG C hereinafter, crystallization time is
0.25-1h；
Step 4, it centrifuges, is dry
Slurry after crystallisation by cooling is centrifuged and is dried, MgSO is obtained4•7H2O。
In step 1, in every cubic metre of desulfurization wastewater, the organic sulfur that 0.05-1kg is added is needed；The weight of the soda ash of addition
Amount is 1.06-2.5 times of calcium ion weight in desulfurization wastewater, and the weight of the flocculant of addition is the 0.5- of desulfurization wastewater weight
3‰。
The carbonate is the mixture of one or more of sodium carbonate, potassium carbonate, magnesium carbonate.
In step 1, reaction time 0.25-1h.
In step 1, feed liquid obtains pretreatment fluid after by-pass filtration and secondary filtration after feed liquid sedimentation after the reaction.
The by-pass filtration and secondary filtration use plate-type filtering, micro-filtration, ultrafiltration or nanofiltration.
The specific processing step of step 2 is：Pretreatment fluid is subjected to the pre-heat treatment, MVR multiple-effect steamings are carried out after the pre-heat treatment
Hair is 200~280mg/l until obtaining sodium chloride content in feed liquid.
For the equipment used when the pre-heat treatment for preheater, preheater selects plate type preheater or calandria preheater, MVR more
For the equipment used when effect evaporation for MVR multi-effect evaporation systems, the heat source of preheater is that the high temperature that MVR multi-effect evaporation systems obtain is cold
Condensate, heat source temperature are 70-120 DEG C.
The MVR multi-effect evaporation systems include multiple-effect falling film evaporator, forced-circulation evaporator and compressor, multiple-effect falling film
Evaporator includes multiple falling film evaporators, and the indirect steam that previous effect falling film evaporator generates is as latter effect falling film evaporator
Heat source, the indirect steam that the indirect steam and forced-circulation evaporator that end effect falling film evaporator generates generate enter compressor, press
Heat source after contracting heating as effect a falling film evaporator and forced-circulation evaporator.It is not only utilized so hot contained by indirect steam
Value, is also more reasonably assigned with internal power source, keeps entire technique more efficient, more energy efficient.
Compressor can be high temperature rise compressor or more low-temperature-rise compressor series connection, can make to enter steam heating 8-
24℃。
In MVR multi-effect evaporation systems, feed temperature pressure highest in an effect falling film evaporator, is 85-110 DEG C.Work as feed liquid
When reaching a certain concentration, feed liquid enters two effect falling film evaporators, and feed temperature reduces in two effect falling film evaporators, is 65-95 DEG C,
It is entered when feed liquid reaches a certain concentration in latter effect falling film evaporator, continues to evaporate, until entering last effect falling liquid film
In evaporator, when reaching a certain concentration, feed liquid enters forced-circulation evaporator and carries out forced-circulation evaporation, forced-circulation evaporation
Device is tiny structure, and feed temperature is 65-95 DEG C, and last feed liquid circulating and evaporating in forced-circulation evaporator goes out moisture, until material
Sodium chloride content is 280mg/l in liquid, and MVR multi-effect evaporation systems are discharged in feed liquid.
Often imitate the high-temperature condensation water generated after the heat source stream heating feed liquid of falling film evaporator and its forced-circulation evaporator
Converge the heating room for entering preheater after shwoot.The heat in the high-temperature condensation water of every effect falling film evaporator is utilized, to locating in advance
It manages liquid and carries out the pre-heat treatment, heat efficiently uses, and reduces the loss of heat, capacity usage ratio higher.
In addition to MVR multi-effect evaporation systems need the raw steam in part to be used as startup heat source when driving, it is no longer necessary to external heat source
（Or require supplementation with minute quantity external heat source）.Start heat source（Supplemental heat source）It is evacuated using the 4th section of low-pressure section of steam turbine, this
Bleed position selection keeps whole system more economical energy saving.Evaporation process uses low-pressure low-temperature, effectively reduces the corrosion journey of system
Degree.
In step 4, for slurry after centrifugation and drying process, remaining feed liquid returns to MVR multi-effect evaporation systems.
Flocculant is existing flocculant, and details are not described herein.
Compared with prior art, the invention has the advantages that：
1, the present invention is in view of China's desulfurization wastewater is containing feature more MgSO4, and organic sulfur, few is only added in preprocessing process
The soda ash and flocculant of amount remove calcium ion and heavy metal ion, retain magnesium ion, MgSO then is made by crystallisation by cooling4•
7H2O products significantly reduce pretreatment cost, improve the economic benefit of processing waster water process.In addition, the present invention is by multiple-effect
Falling film evaporation technology and MVR forced circulation evaporation techniques dexterously combine, both comprehensive advantage, it is more efficient reasonably
Heat source is distributed, to reach more energy-efficient effect.The present invention reduces corrosion phenomenon using low-temperature evaporation, is a kind of low cost section
The about desulfurization wastewater technique of zero discharge of type, realizes the zero-emission of power plant desulfurization wastewater.
2, pretreatment stage need to only add a small amount of soda ash, organic sulfur and flocculant, remove calcium ion and heavy metal ion.By
Do not have to removal magnesium ion in this technique, does not just have to that quick lime is added yet, extra calcium ion would not be introduced, also there is no need to be added
Soda ash removes extra calcium ion, not only simplifies production craft step, and reduces the usage amount of the reagents such as soda ash, thus saves
Pretreatment cost.
3, this automation technolo degree is high：Preprocessing part control is accurate, and medicament addition is accurate, and it is few to generate sludge quantity；
Whole system requires manning few, has saved human cost.
4, this technique combines the advantages of multiple-effect falling film evaporation technology and MVR forced circulation evaporation techniques.In view of an effect
The characteristics of falling film evaporator pressure is higher, and the forced-circulation evaporator lining liquid salt content of end effect is big, the elevation of boiling point, by compressor
Heat source of the compressed high temperature and high pressure steam as the two.And the previous effect falling film evaporator of latter effect falling film evaporator is secondary
Steam is as heat source.It is more reasonably assigned with internal power source in this way, keeps entire technique more efficient, it is more energy efficient.
5, this technique is MgSO by product made from crystallisation by cooling4•7H2O products improve the warp of processing waster water process
Ji benefit.
Description of the drawings
Fig. 1 is present invention process flow diagram；
Fig. 2 is the structural schematic diagram for the entire desulfurization wastewater treatment system that the present invention uses；
Fig. 3 is the device structure schematic diagram that step 1 is used；
Fig. 4 is the device structure schematic diagram that step 2- steps 4 of the present invention are used.
Reference numeral 1, pump, 2, high-level storage groove, 3, reactive tank, 4, subsider, 5, surge tank, 6, grade one filter, 7, two
Grade filter, 8, preheater, 9, one effect falling film evaporator, 10, two effect falling film evaporators, 11, forced-circulation evaporator, 12, from
Heart compressor, 13, condensate water pot, 14, crystallisation by cooling kettle, 15, cyclone, 16, centrifuge, 17, gas-liquid separator, 18, dry
Bed.
Specific implementation mode
The present invention is to provide a kind of desulfuration waste water treatment process comprising pre-treatment step, evaporation-concentration step, cooling
Crystallisation step and centrifugation are dried step, and the product finally obtained is MgSO4•7H2O。
Pre-treatment step concrete technology is：By the effect of pump 1, carbonate and flocculant are pumped into high-level storage groove respectively
In 2, then desulfurization wastewater is imported into reactive tank 3, by high-level storage groove 2 carbonate and flocculant be added separately to react
In slot 3, organic sulfur is added in reactive tank and is reacted（It needs to be added in every cubic metre of desulfurization wastewater in reactive tank every
The organic sulfur of 0.05-1kg）, the weight of the carbonate being added in reactive tank is weight of calcium carbonate in desulfurization wastewater in reactive tank 3
1.06-2.5 times, the weight of the flocculant of addition is the 0.5-3 ‰ of desulfurization wastewater weight in reactive tank 3, and flocculant uses existing
Flocculant.Reaction time is 0.25-1h, and the temperature and pressure of reaction are normal temperature and pressure.After the completion of reaction, feed liquid is led
Enter and carry out precipitation process into subsider 4, achievees the purpose that remove calcium ion and heavy metallic salt, be then introduced into feed surge tank
After being buffered in 5, it is pumped into grade one filter 6 by pump 1 and carries out by-pass filtration（By-pass filtration can be used plate-type filtering, micro-filtration,
Ultrafiltration or nanofiltration）, then into carrying out secondary filtration in secondary filter 7（Secondary filtration can be used plate-type filtering, micro-filtration,
Ultrafiltration or nanofiltration）, pre-treatment step control is accurate, and medicament addition is accurate, and it is few to generate sludge quantity；Whole system requires to be equipped with people
Member is few, has saved human cost.
Evaporation-concentration step concrete technology is：The pretreatment fluid obtained by pretreatment is imported into preheater 8 and is carried out
The pre-heat treatment, the feed liquid after the pre-heat treatment imported into MVR multi-effect evaporation systems and are evaporated processing.MVR multiple-effect evaporations system
System is by two effects（Or multiple-effect）Falling film evaporator（A gas-liquid separator 17 is connected after often imitating falling film evaporator）, a forced circulation
Evaporator 11（A gas-liquid separator 17 is connected afterwards）It is formed with a centrifugal compressor 12.Wherein one effect falling film evaporator 9 is given birth to
At indirect steam as two effect falling film evaporators 10 heat source（The indirect steam that two effect falling film evaporators generate is dropped as triple effect
The heat source of film evaporator）；Two（End）It imitates described in the indirect steam entrance that falling film evaporator 10 and forced-circulation evaporator 11 generate
Centrifugal compressor 12, the heat source after centrifugal compressed heating as effect a falling film evaporator 9 and forced-circulation evaporator 11.Centrifugation pressure
Contracting machine 12 can be high temperature rise compressor or more low-temperature-rise compressor series connection, can make to enter 8-24 DEG C of steam heating.In this way
Indirect steam institute calorific value is not only utilized, is also more reasonably assigned with internal power source, keeps entire technique more efficient, it is more energy efficient.
In MVR multi-effect evaporation systems, after preprocessor 8 carries out the pre-heat treatment, feed liquid enters in an effect falling film evaporator 9, and one
Feed temperature highest in falling film evaporator 9 is imitated, is 85-110 DEG C.When feed liquid reaches a certain concentration（Setting in advance）When, feed liquid into
Enter two effect falling film evaporators 10, feed temperature reduces in two effect falling film evaporators 10, is 65-95 DEG C, when feed liquid reaches certain dense
Degree（Setting in advance）When enter in latter effect falling film evaporator, continue to evaporate, until enter last effect falling film evaporator
In, when reaching a certain concentration（Setting in advance）When, feed liquid is from two（End）It imitates falling film evaporator 10 and enters forced-circulation evaporator 11
Forced-circulation evaporation is carried out, forced-circulation evaporator 11 is tiny structure, and feed temperature is 65-95 DEG C, and last feed liquid is forcing to follow
Circulating and evaporating goes out moisture in ring evaporator 11, and until sodium chloride content is 200-280mg/l in feed liquid, MVR multiple-effect is discharged in feed liquid
Vapo(u)rization system.It often imitates in falling film evaporator, high-temperature condensation water, the forced-circulation evaporator 11 generated after heat source stream heating feed liquid
In high-temperature condensation water converge and enter in condensate water pot 13, into heating feed liquid in the heating room of preheater 8 after shwoot.Often imitate
Thermal energy in the high-temperature condensation water that falling film evaporator and circulating evaporator 11 processed evaporation generate has carried out secondary use, recycles thermal energy
Condensed water afterwards reaches recycle water standard and is used, and the temperature for importeding into the high-temperature condensation water in preheater is 70-120 DEG C.
In addition to MVR multi-effect evaporation systems need the raw steam in part to be used as startup heat source when driving, it is no longer necessary to external heat source
（Or require supplementation with minute quantity external heat source）.Start heat source（Supplemental heat source）It is evacuated using the 4th section of low-pressure section of steam turbine, this
Bleed position selection keeps whole system more economical energy saving.Evaporation process uses low-pressure low-temperature, effectively reduces the corrosion journey of system
Degree.
Crystallisation by cooling step concrete technology is：Will through evaporation and concentration feed liquid imported into crystallisation by cooling kettle 14 carry out it is cold
But it crystallizes, is distinguished using sodium chloride and the variation of magnesium sulfate solubility with temperature, control cooling temperature is at 20 DEG C hereinafter, crystallization stops
Time is 0.25-1h, and MgSO is precipitated4•7H2O crystal.
Centrifugation, drying process step concrete technology are：Turn the slurry pump to centrifugal dehydration system by crystallisation by cooling
（Including cyclone 15 and centrifuge 16）Centrifugal dehydration treatment is carried out, is then then sent through on drying bed 18 and is dried, obtain
MgSO4•7H2O is packaged with packing machine and is packed.
With reference to embodiment, the invention will be further described, and described embodiment is only a present invention part
Embodiment is not whole embodiment.Based on the embodiments of the present invention, those skilled in the art are not making
Other embodiments used obtained under the premise of creative work, belong to protection scope of the present invention.
Embodiment 1
A kind for the treatment of process for desulfurization wastewater is present embodiments provided, by obtaining MgSO after the process4•7H2O,
The usage amount for not only having saved reagent simplifies processing step, and has recycled the high MgSO of economic value4•7H2O is a kind of
The desulfurization wastewater technique of zero discharge of inexpensive economizing type, realizes the zero-emission of power plant desulfurization wastewater.The technique specifically include as
Lower step：
Step 1, it pre-processes
Organic sulfur, soda ash and flocculant are added into desulfurization wastewater to be reacted, the calcium ion and a huge sum of money in desulfurization wastewater are removed
Belong to ion, obtains pretreatment fluid；The weight of the organic sulfur of addition, soda ash and flocculant is：
Organic sulfur：According to 1 m3The requirement that 0.05kg organic sulfurs are added in desulfurization wastewater is added,
Soda ash：It is weighed according to the weight of calcium ion in desulfurization wastewater, has 1g calcium ions that 1.06g is just added in desulfurization wastewater pure
Alkali,
Flocculant：The flocculant of addition is the 0.5 ‰ of desulfurization wastewater weight.
Organic sulfur, soda ash, flocculant and desulfurization wastewater are mixed in reactive tank, reacted under normal temperature and pressure conditions, instead
It is 1h between seasonable, reaction generates precipitation of calcium carbonate and heavy metallic salt precipitation, and the feed liquid after reaction is removed by entering subsider
Precipitation of calcium carbonate and heavy metallic salt precipitation, the precipitation of calcium carbonate that reaction clarification generates, as " limestone-gypsum flue gas desulfurizing method "
Desulfurizing agent use.Feed liquid carries out once filtering and secondary filter after subsider, and primary filtering and secondary filter use plate
Formula filtering, micro-filtration, ultrafiltration or nanofiltration.Pretreatment fluid is obtained after filtering.
Step 2, it is concentrated by evaporation
The pretreatment fluid obtained by pretreatment is imported into preheater 8 and carries out the pre-heat treatment, the material after the pre-heat treatment
Liquid imported into MVR multi-effect evaporation systems and is evaporated processing.MVR multi-effect evaporation systems are by two effects（Or multiple-effect）Falling film evaporator
（A gas-liquid separator 17 is connected after often imitating falling film evaporator）, a forced-circulation evaporator 11（A gas-liquid point is connected afterwards
From device 17）It is formed with a centrifugal compressor 12.The indirect steam that wherein one effect falling film evaporator 9 generates is steamed as two effect falling liquid films
Send out the heat source of device 10（Heat source of the indirect steam that two effect falling film evaporators generate as triple effect falling film evaporator）；Two（End）Effect drop
The indirect steam that film evaporator 10 and forced-circulation evaporator 11 generate enters the centrifugal compressor 12, after centrifugal compressed heating
Heat source as effect a falling film evaporator 9 and forced-circulation evaporator 11.Centrifugal compressor 12 can be high temperature rise compressor, also may be used
It connects for more low-temperature-rise compressors, can make to enter 8-24 DEG C of steam heating.Indirect steam institute calorific value is not only utilized in this way,
It is also more reasonably assigned with internal power source, keeps entire technique more efficient, it is more energy efficient.In MVR multi-effect evaporation systems, by pretreatment
After device 8 carries out the pre-heat treatment, feed liquid enters in an effect falling film evaporator 9, feed temperature highest in an effect falling film evaporator 9,
It is 85 DEG C.When feed liquid reaches a certain concentration（Setting in advance）When, feed liquid enters two effect falling film evaporators 10, two effect falling film evaporators
Feed temperature reduces in 10, is 65 DEG C, when feed liquid reaches a certain concentration（Setting in advance）When enter latter effect falling film evaporator
In, continue to evaporate, until entering in last effect falling film evaporator, when reaching a certain concentration（Setting in advance）When, feed liquid from
Two（End）It imitates falling film evaporator 10 and enters the progress forced-circulation evaporation of forced-circulation evaporator 11, forced-circulation evaporator 11 is micro-
Negative pressure, feed temperature are 65 DEG C, and last feed liquid circulating and evaporating in forced-circulation evaporator 11 goes out moisture, until chlorination in feed liquid
Sodium content is 200~280mg/l, and MVR multi-effect evaporation systems are discharged in feed liquid.It often imitates in falling film evaporator, heat source stream heating material
High-temperature condensation water in the high-temperature condensation water that is generated after liquid, forced-circulation evaporator 11, which converges, to be entered in condensate water pot 13, is dodged
Enter after hair in the heating room of preheater 8 and heats feed liquid.The height that often effect falling film evaporator and circulating evaporator 11 processed evaporation generate
Thermal energy in warm condensed water has carried out secondary use, and the condensed water after recycling thermal energy reaches recycle water standard and is used, imports
Temperature to the high-temperature condensation water in preheater is 70 DEG C.
In addition to MVR multi-effect evaporation systems need the raw steam in part to be used as startup heat source when driving, it is no longer necessary to external heat source
（Or require supplementation with minute quantity external heat source）.Start heat source（Supplemental heat source）It is evacuated using the 4th section of low-pressure section of steam turbine, this
Bleed position selection keeps whole system more economical energy saving.Evaporation process uses low-pressure low-temperature, effectively reduces the corrosion journey of system
Degree.
Step 3, crystallisation by cooling
Crystallisation by cooling is carried out by being imported into crystallisation by cooling kettle 14 by the feed liquid being concentrated by evaporation, it is molten with magnesium sulfate using sodium chloride
Xie Du varies with temperature difference, and for control cooling temperature at 20 DEG C, the crystallization residence time is 0.25h, and MgSO is precipitated4•7H2O crystal.
Step 4, it centrifuges, is dry
Turn the slurry pump to centrifugal dehydration system by crystallisation by cooling（Including cyclone 15 and centrifuge 16）It is centrifuged
Then dehydration is then sent through on drying bed 17 and is dried, obtains MgSO4•7H2O is packaged with packing machine and is packed.
Embodiment 2
The present embodiment is substantially the same manner as Example 1, unlike：
In step 1, organic sulfur：According to 1 m3The requirement that 0.08kg organic sulfurs are added in desulfurization wastewater is added,
Soda ash replaces with magnesium carbonate：It is weighed according to the weight of calcium ion in desulfurization wastewater, has 1g calcium ions in desulfurization wastewater just
1.1g magnesium carbonate is added,
Flocculant：The flocculant of addition is the 0.6 ‰ of desulfurization wastewater weight.
Organic sulfur, magnesium carbonate, flocculant and desulfurization wastewater are mixed in reactive tank, reacted under normal temperature and pressure conditions,
Reaction time is 0.55h.Primary filtering and the filter type of secondary filter are：Ultrafiltration.
In step 2, feed temperature is 88 DEG C in an effect falling film evaporator 9.Feed temperature is in two effect falling film evaporators 10
70 DEG C, feed temperature is 68 DEG C in forced-circulation evaporator, and the temperature for importeding into the high-temperature condensation water in preheater is 78 DEG C.
Cooling temperature is controlled in step 3 at 18 DEG C, the crystallization residence time is 0.55h.
Embodiment 3
Organic sulfur：According to 1 m3The requirement that 0.12kg organic sulfurs are added in desulfurization wastewater is added,
Soda ash replaces with potassium carbonate：It is weighed according to the weight of calcium ion in desulfurization wastewater, has 1g calcium ions in desulfurization wastewater just
1.5g potassium carbonate is added,
Flocculant：The flocculant of addition is the 1.2 ‰ of desulfurization wastewater weight.
Organic sulfur, potassium carbonate, flocculant and desulfurization wastewater are mixed in reactive tank, reacted under normal temperature and pressure conditions,
Reaction time is 0.75h.Primary filtering and the filter type of secondary filter are：Micro-filtration.
In step 2, feed temperature is 90 DEG C in an effect falling film evaporator 9.Feed temperature is in two effect falling film evaporators 10
80 DEG C, feed temperature is 72 DEG C in forced-circulation evaporator, and the temperature for importeding into the high-temperature condensation water in preheater is 80 DEG C.
Cooling temperature is controlled in step 3 at 20 DEG C hereinafter, the crystallization residence time is 0.65h.
Embodiment 4
Organic sulfur：According to 1 m3The requirement that 0.6kg organic sulfurs are added in desulfurization wastewater is added,
Soda ash replaces with the mixture of soda ash and magnesium carbonate：It is weighed according to the weight of calcium ion in desulfurization wastewater, desulfurization wastewater
In have the mixture that 1.8g soda ash and magnesium carbonate is just added in 1g calcium ions,
Flocculant：The flocculant of addition is the 3 ‰ of desulfurization wastewater weight.
The mixture, flocculant and desulfurization wastewater of organic sulfur, soda ash and magnesium carbonate are mixed in reactive tank, it is normal in room temperature
It is reacted under the conditions of pressure, reaction time 0.25h.Primary filtering and the filter type of secondary filter are：Plate-type filtering.
In step 2, feed temperature is 100 DEG C in an effect falling film evaporator 9.Feed temperature is in two effect falling film evaporators 10
88 DEG C, feed temperature is 78 DEG C in forced-circulation evaporator, and the temperature for importeding into the high-temperature condensation water in preheater is 100 DEG C.
Cooling temperature is controlled in step 3 at 15 DEG C, the crystallization residence time is 1h.
Embodiment 5
Organic sulfur：According to 1 m3The requirement that 1kg organic sulfurs are added in desulfurization wastewater is added,
Soda ash replaces with the mixture of magnesium carbonate and potassium carbonate：It is weighed according to the weight of calcium ion in desulfurization wastewater, desulfurization is useless
There are 1g calcium ions that the mixture of 2.5g magnesium carbonate and potassium carbonate is just added in water,
Flocculant：The flocculant of addition is the 3 ‰ of desulfurization wastewater weight.
The mixture, flocculant and desulfurization wastewater of organic sulfur, magnesium carbonate and potassium carbonate are mixed in reactive tank, in room temperature
It is reacted under condition of normal pressure, reaction time 0.25h.Primary filtering and the filter type of secondary filter are：Nanofiltration.
In step 2, feed temperature is 110 DEG C in an effect falling film evaporator 9.Feed temperature is in two effect falling film evaporators 10
95 DEG C, feed temperature is 95 DEG C in forced-circulation evaporator, and the temperature for importeding into the high-temperature condensation water in preheater is 120 DEG C.
Cooling temperature is controlled in step 3 at 12 DEG C hereinafter, the crystallization residence time is 0.25h.
Claims (7)
1. a kind of desulfuration waste water treatment process, it is characterised in that：It comprises the technical steps that：
Step 1, it pre-processes
Organic sulfur is added into desulfurization wastewater, carbonate and flocculant are reacted, remove calcium ion in desulfurization wastewater and again
Metal ion obtains pretreatment fluid；
Step 2, it is concentrated by evaporation
Pretreatment fluid is evaporated concentration, until it is 200-280mg/l to obtain in feed liquid sodium chloride content；
Step 3, crystallisation by cooling
Slurry is obtained by crystallisation by cooling is carried out by the feed liquid being concentrated by evaporation, crystallization temperature is 20 DEG C hereinafter, crystallization time is
0.25-1h；
Step 4, it centrifuges, is dry
Slurry after crystallisation by cooling is centrifuged and is dried, MgSO is obtained4•7H2O。
2. a kind of desulfuration waste water treatment process according to claim 1, it is characterised in that：In step 1, every cubic metre de-
In sulphur waste water, the organic sulfur that 0.05-1kg is added is needed；The weight of the carbonate of addition is calcium ion weight in desulfurization wastewater
1.06-2.5 times, the weight of the flocculant of addition is the 0.5-3 ‰ of desulfurization wastewater weight.
3. a kind of desulfuration waste water treatment process according to claim 1 or 2, it is characterised in that：The carbonate is carbonic acid
One or more mixtures of sodium, magnesium carbonate, potassium carbonate.
4. a kind of desulfuration waste water treatment process according to claim 1, it is characterised in that：In step 1, the reaction time is
0.25-1h。
5. a kind of desulfuration waste water treatment process according to claim 1, it is characterised in that：In step 1, material after the reaction
Feed liquid obtains pretreatment fluid after by-pass filtration and secondary filtration after liquid sedimentation.
6. a kind of desulfuration waste water treatment process according to claim 1, it is characterised in that：The specific processing step of step 2
For：Pretreatment fluid is subjected to the pre-heat treatment, MVR multiple-effect evaporations are carried out after the pre-heat treatment, until obtaining sodium chloride content in feed liquid
For 200-280mg/l.
7. a kind of desulfuration waste water treatment process according to claim 6, it is characterised in that：MVR multiple-effect evaporations include multiple-effect
Falling film evaporation and forced-circulation evaporation, in multiple-effect falling film evaporation, feed temperature is 85-110 DEG C in an effect falling film evaporation, two effect drops
Feed temperature is 65-95 DEG C in film evaporation, and feed temperature is 65-95 DEG C in forced-circulation evaporation.
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| CN110217934A (en) * | 2019-07-22 | 2019-09-10 | 四川省川南酿造有限公司 | A kind of preparation method of pickled vegetable brine MVR evaporative crystallization |
| CN111892218A (en) * | 2020-06-29 | 2020-11-06 | 张建东 | High-efficient low-cost desulfurization waste water treatment's of coal fired power plant zero discharge system |
| CN112194298A (en) * | 2020-08-07 | 2021-01-08 | 东方电气集团东方锅炉股份有限公司 | System and method for recycling wastewater of whole power plant |
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