CN105502792A - Zero-discharge treatment method of desulfurization waste water - Google Patents

Zero-discharge treatment method of desulfurization waste water Download PDF

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CN105502792A
CN105502792A CN201610054012.1A CN201610054012A CN105502792A CN 105502792 A CN105502792 A CN 105502792A CN 201610054012 A CN201610054012 A CN 201610054012A CN 105502792 A CN105502792 A CN 105502792A
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waste water
effect
water
evaporating
concentration
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CN105502792B (en
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赵齐
吴学良
郭桦
刘汉强
吕洲
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GUODIAN NEW ENERGY TECHNOLOGY INSTITUTE
Chengdu Rui Si Green Technology Limited-Liability Co
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GUODIAN NEW ENERGY TECHNOLOGY INSTITUTE
Chengdu Rui Si Green Technology Limited-Liability Co
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F9/00Multistage treatment of water, waste water, or sewage
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/02Treatment of water, waste water, or sewage by heating
    • C02F1/04Treatment of water, waste water, or sewage by heating by distillation or evaporation
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/52Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/5236Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents
    • C02F1/5245Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using inorganic agents using basic salts, e.g. of aluminium and iron
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/52Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities
    • C02F1/54Treatment of water, waste water, or sewage by flocculation or precipitation of suspended impurities using organic material
    • C02F1/56Macromolecular compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F2001/007Processes including a sedimentation step
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00Nature of the contaminant
    • C02F2101/10Inorganic compounds
    • C02F2101/20Heavy metals or heavy metal compounds
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00Apparatus for treatment of water, waste water or sewage
    • C02F2201/002Construction details of the apparatus
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2301/00General aspects of water treatment
    • C02F2301/08Multistage treatments, e.g. repetition of the same process step under different conditions

Abstract

The invention discloses a zero-discharge treatment method of desulfurization waste water. The method comprises the following steps that after the desulfurization waste water is treated through a primary chemical precipitation treatment system (1), sodium carbonate is added into the desulfurization waste water to conduct a reaction, and then the desulfurization waste water is sent into a multi-effect evaporating device for evaporation after being precipitated and filtered; partial mother solution in the multi-effect evaporating device is introduced into the primary chemical precipitation treatment system (1) to be treated before the concentration of scaling ions of a mother solution in the multi-effect evaporating device reaches the scaling concentration or before the concentration of corrosion ions reaches the concentration of corroding heat exchange tubes. The zero-discharge treatment method of the desulfurization waste water has the advantages that scaling tendency of the desulfurization waste water is reduced, and the phenomena that due to scaling, heat transfer is affected, and corrosion of the heat exchange tubes in an evaporation chamber is caused are avoided; meanwhile, the desulfurization waste water is converted into a solution system of which the solute is mainly NaCl, multi-effect vacuum evaporation concentration crystallization is conducted on the desulfurization waste water by means of waste steam of a coal-fired power plant, secondary industrial salt byproducts are generated, and zero discharge of the desulfurization waste water is achieved.

Description

A kind of zero emission treatment of desulfured waste water
Technical field
The present invention relates to field technical field of waste water processing, particularly, relate to a kind of zero emission treatment of desulfured waste water.
Background technology
Coal power station, in wet fuel gas desulfurizing technology process, in order to maintain the balance of desulfurizer serum recycle system, needs timing from absorption tower waste discharge, i.e. desulfurization wastewater.Compared with the trade effluent that it is general with coal power station, water-quality ratio is more special, and wherein a lot of material is require the strict first kind pollutent controlled in national environmental standard, and be mainly manifested in the following aspects: (1) waste water is slightly acidic, PH is 4 ~ 6; Secondly (2) suspension content is high, and particle is little, and main component is gypsum, also has from the calcium carbonate added in the flying dust of flue gas, sweetening process and calcium sulfite etc.; (3) muriate, fluorochemical etc. containing solubility in waste water; (4) contain the heavy metal elements such as Pb, Cd, Cr, Ni, Hg, Co, Cu, Al, Zn, Mn in waste water, wherein major part is the heavy metal element of restriction in the linear sewage drainage standard of thermal power plant (GB8978-1996).(5) from water-quality guideline, in desulfurization wastewater, chemical oxygen demand (COD) is also one of transnormal items.
Current domestic modal method for treating desulfurized wastewater is chemical precipitation method, and the method utilizes physics, chemical process to make desulfurization wastewater reach the existing emission standard of country by the means such as neutralization, sedimentation, the flocculate and clarify most suspended substances, heavy metal ion etc. removed in desulfurization wastewater.Still containing the Ca be dissolved in waste water in waste water after the method process 2+, Mg 2+, Cl -, SO 4 2-etc. the salinity of high density, if long can the generation surrounding water of long-time directly discharge has a strong impact on.
Summary of the invention
Technical problem to be solved by this invention is to provide a kind ofly carries out multiple-effect vacuum evaporating, concentrating and crystallizing to desulfurization wastewater, reclaims moisture and produce industrial goods salt and effectively can avoid fouling or corrode the zero emission treatment of desulfured waste water that impacts evaporator room heat transfer tube.
The present invention's adopted technical scheme that solves the problem is:
A kind of zero emission treatment of desulfured waste water, comprise the following steps: desulfurization wastewater is after the process of one-level chemical precipitation treatment system, in desulfurization wastewater, add sodium carbonate react, then desulfurization wastewater is precipitated, send into multi-effect evaporating device after filtering to evaporate, the steam of evaporation output obtains water of condensation after heat exchange, the salt slurry of evaporation output enters equipment for separating liquid from solid and carries out solid-liquid separation, obtain solid salt, before in multi-effect evaporating device, the concentration of the scale-forming ion of mother liquor reaches fouling concentration or corrosive ions concentration reach corrosion heat transfer tube concentration before the partial mother liquid in multi-effect evaporating device is introduced the process of one-level chemical precipitation treatment system, this partial mother liquid is through the process of chemical precipitation treatment system, to reduce in mother liquor after scale-forming ion concentration and corrosive ions concentration, again enter multi-effect evaporating device to evaporate.
The present invention by adding Na in the waste water after chemical precipitation method process 2cO 3solution carries out second order reaction process, with CO 3 2-precipitation Ca wherein 2+, Mg 2+ion, reduces the Ca in water 2+, Mg 2+ionic concn, reduces the fouling tendency of desulfurization wastewater; Desulfurization wastewater to be changed into solute be NaCl is simultaneously main solution system.Desulfurization wastewater after second order reaction process, carry out multiple-effect vacuum evaporating, concentrating and crystallizing to it, moisture in desulfurization wastewater is separated with salinity, moisture is recycled, and produce the secondary industrial goods salt byproduct that main component is NaCl, realize the treatment system of desulfurization wastewater zero release.This treatment system is that the highly purified clear water of main generation is recycled, and produces the secondary industrial goods salt byproduct that main component is NaCl simultaneously, creates added value.Before the concentration of the scale-forming ion in multi-effect evaporating device in mother liquor reaches fouling concentration or corrosive ions concentration reach corrosion heat transfer tube concentration before the partial mother liquid in multi-effect evaporating device is introduced one-level chemical precipitation treatment system, thus reduce the ionic concn of mother liquor in multiple-effect evaporation concentration and crystallization device, avoid the generation of fouling or corrosion.
Further, also comprise mother liquor solid-liquid separation obtained and be introduced into the step that multi-effect evaporating device carries out evaporating.
Further, before the scale-forming ion concentration being also included in the mother liquor that solid-liquid separation obtains reaches fouling concentration or before corrosive ions concentration reaches corrosion heat transfer tube concentration, this mother liquor is introduced the step of one-level chemical precipitation treatment system process.Avoid the mother liquor with high density scale-forming ion and corrosive ions and enter multiple-effect evaporation concentration and crystallization device, so avoid high density scale-forming ion can on evaporator room heat transfer tube fouling and after affecting heat transfer, enrichment method the corrosive ions of high density can cause the generation of the phenomenons such as corrosion to evaporator room heat transfer tube.
Further, the water of condensation that produced by multi-effect evaporating device is also comprised to the step entering the desulfurization wastewater before multi-effect evaporating device and carry out preheating.Thus namely desulfurization wastewater is removed scale-forming ion and corrosive ions before entering multi-effect evaporating device.
Preferably, the exhaust steam that multi-effect evaporating device adopts power station to send here, as heating steam, utilizes exhaust steam of electric power plant to carry out multiple-effect vacuum evaporating, concentrating and crystallizing to desulfurization wastewater, moisture in desulfurization wastewater is separated with salinity.Thus take full advantage of the heat energy of exhaust steam of electric power plant, save resource, avoid the waste of heat energy.
Further, described desulfurization wastewater enters the step that multi-effect evaporating device carries out evaporating:
Desulfurization wastewater advection enters multiple evaporating, concentrating and crystallizing devices of multi-effect evaporating device, the heating steam of first effect evaporating, concentrating and crystallizing device is provided by external steam source, the secondary steam that last effect produces enters next effect evaporating, concentrating and crystallizing device, dense salt slurry adopts and turns material mode, the mother liquor improving salinity through last effect enters next effect evaporating, concentrating and crystallizing device, and the mother liquor of end effect evaporating, concentrating and crystallizing device enters equipment for separating liquid from solid.
Further, in each effect evaporating, concentrating and crystallizing device, the water of condensation that heating steam is formed flows into level of condensation weighing apparatus bucket, the flash-off steam produced in water of condensation balance bucket returns heating chamber, the utilization of condensed water water of condensation balance bucket that last effect evaporating, concentrating and crystallizing device produces deliver to after collecting after an effect water of condensation balance bucket, deliver to next after imitating with rear one the water of condensation mixing shwoot some vapor that heating chamber produces and imitate water of condensation and balance bucket.
Preferably, the water of condensation introducing preheater that the water of condensation of end effect evaporating, concentrating and crystallizing device balances in bucket carries out preheating to entering the desulfurization wastewater before multi-effect evaporating device.
Further, the steam of the evaporator room of last effect evaporating, concentrating and crystallizing device enters vapour condensation device.
Further, described desulfurization wastewater adopts existing routine techniques through the step of one-level chemical precipitation treatment system process, generally comprises following steps: by desulfurization wastewater introduce in and case, in and case in add aqua calcis adjust ph, make Mg simultaneously 2+, Pb 2+, Cr 3+, Cd 2+plasma is precipitated out with hydroxide form, the F in waste water -ion is with CaF 2form settles, in and the waste water that completes reaction in case enter sludge box, and add organosulfur in sludge box, make remaining Pb 2+, Cr 3+, Cd 2+be precipitated out with sulphided form etc. heavy metal ion, the waste water completing reaction in sludge box enters flocculation tanks, flocculation agent (chloro sulphuric acid iron) is added and/or coagulant aids (PAM) makes throw out in conjunction with sedimentation in flocculation tanks, through flocculation tanks discharge waste water through settler clarification after, complete the process of one-level chemical precipitation treatment system.
The concentration of Controlling System internal corrosive ion and fouling tendency type ion is in two ways adopted in limits: 1) multi-effect evaporating device mother liquor reflux pipe is set to front end chemical precipitation treatment system in treatment method; 2) mother liquor reflux of equipment for separating liquid from solid generation is to chemical precipitation treatment system.
To sum up, the invention has the beneficial effects as follows:
1, the salinity in the desulfurization wastewater after solving chemical precipitation method process directly discharges problems such as the pollutions of surrounding water; Utilize coal power station exhaust steam to carry out multiple-effect vacuum evaporating, concentrating and crystallizing to desulfurization wastewater, moisture in desulfurization wastewater is separated with salinity, reclaim water utilization, and produce the secondary industrial goods salt byproduct that main component is NaCl, realize the zero release of desulfurization wastewater.
Utilize the present invention, for the water yield of the desulfurization wastewater that need process, in conjunction with the desulfurization wastewater for different treatment amount, calculate required heat interchanging area, select suitable middle effect quantity to realize the zero release of desulfurization wastewater in conjunction with investment etc.
Before the concentration of the scale-forming ion 2, in evaporator room feed liquid reaches fouling concentration or before corrosive ions concentration reaches corrosion heat transfer tube concentration, the feed liquid of discharge section evaporator room to chemical precipitation treatment system, avoid high density scale-forming ion can on evaporator room heat transfer tube fouling and after affecting heat transfer, enrichment method the corrosive ions of high density can cause the generation of the phenomenons such as corrosion to evaporator room heat transfer tube.
3, the heating steam that the secondary steam that evaporation produces is imitated as next, steam is repeatedly utilized, and has saved the energy.
4, before the scale-forming ion concentration in mother vat in mother liquor reaches fouling concentration or before corrosive ions concentration reaches corrosion heat transfer tube concentration, partial mother liquid in mother vat is introduced one-level chemical precipitation treatment system, avoid the mother liquor with high density scale-forming ion and corrosive ions and enter multiple-effect evaporation concentration and crystallization device, avoid high density scale-forming ion can on evaporator room heat transfer tube fouling and after affecting heat transfer, enrichment method the corrosive ions of high density can cause the generation of the phenomenons such as corrosion to evaporator room heat transfer tube.
5, evaporator room form adopts forced circulation evaporation room, each effect evaporator room is configured with forced circulation pump, strengthens the flow velocity of desulfurization wastewater in evaporator room heat transfer tube, improves evaporator room heat transfer coefficient, reduce facility investment, reduce salinity fouling possibility on heat transfer tube simultaneously.
6, multi-effect evaporation system feeding manner adopts advection charging, reduces fouling tendency.
7, the salt of each effect evaporator room output goes to middle effect from head effect, goes to end effect successively, discharges from end effect, reduces and discharges salt slurry temperature, reduce system thermosteresis, reduce steam consumption, save energy.
8, steam condensate water of condensation balance bucket is collected, and shwoot goes out some vapor as heating steam, reduces steam consumption, save energy.
9, utilize steam condensate to carry out preheating to desulfurization wastewater, improve and enter evaporator room desulfurization wastewater temperature, reduce steam consumption, save energy.
10, vacuum pump is set, the non-condensable gases in extraction system, improves end effect vacuum tightness, improve effective heat transfer temperature difference, reduce steam consumption, save energy.
Accompanying drawing explanation
Fig. 1 is structural representation of the present invention.
Mark and corresponding component title in accompanying drawing:
1-one-level chemical precipitation treatment system, 2-second order reaction case, 3-Secondary clarifier, 4-strainer, 5-preheater, 6-recycle pump, 7-heating chamber, 8-evaporator room, 9-water of condensation balance bucket, 10-thickener, 11-whizzer, 12-mother vat, 13-surface condenser, 14-condensed water bucket, 15-vacuum pump.
Embodiment
Below in conjunction with embodiment and accompanying drawing, to the detailed description further of the present invention's do, but embodiments of the present invention are not limited thereto.
Embodiment:
As shown in Figure 1, a kind of zero emission treatment of desulfured waste water, comprise the following steps: desulfurization wastewater is after the process of one-level chemical precipitation treatment system 1, in desulfurization wastewater, add sodium carbonate react, then desulfurization wastewater is precipitated, send into multi-effect evaporating device after filtering to evaporate, the steam of evaporation output obtains water of condensation after heat exchange, the salt slurry of evaporation output enters equipment for separating liquid from solid and carries out solid-liquid separation, obtain solid salt, before in multi-effect evaporating device, the concentration of the scale-forming ion of mother liquor reaches fouling concentration or corrosive ions concentration reach corrosion heat transfer tube concentration before the partial mother liquid in multi-effect evaporating device introduced one-level chemical precipitation treatment system 1 process, this partial mother liquid is through the process of chemical precipitation treatment system, to reduce in mother liquor after scale-forming ion concentration and corrosive ions concentration, again enter multi-effect evaporating device to evaporate.
The present invention by adding Na in the waste water after chemical precipitation method process 2cO 3solution carries out second order reaction process, with CO 3 2-precipitation Ca wherein 2+, Mg 2+ion, reduces the Ca in water 2+, Mg 2+ionic concn, reduces the fouling tendency of desulfurization wastewater; Desulfurization wastewater to be changed into solute be NaCl is simultaneously main solution system.Desulfurization wastewater after second order reaction process, carry out multiple-effect vacuum evaporating, concentrating and crystallizing to it, moisture in desulfurization wastewater is separated with salinity, moisture is recycled, and produce the secondary industrial goods salt byproduct that main component is NaCl, realize the treatment system of desulfurization wastewater zero release.This treatment system is that the highly purified clear water of main generation is recycled, and produces the secondary industrial goods salt byproduct that main component is NaCl simultaneously, creates added value.Before the concentration of the scale-forming ion in multi-effect evaporating device in mother liquor reaches fouling concentration or corrosive ions concentration reach corrosion heat transfer tube concentration before the partial mother liquid in multi-effect evaporating device is introduced one-level chemical precipitation treatment system 1, thus reduce the ionic concn of mother liquor in multiple-effect evaporation concentration and crystallization device, avoid the generation of fouling or corrosion.
Further, also comprise mother liquor solid-liquid separation obtained and be introduced into the step that multi-effect evaporating device carries out evaporating.
Further, before the scale-forming ion concentration being also included in the mother liquor that solid-liquid separation obtains reaches fouling concentration or before corrosive ions concentration reaches corrosion heat transfer tube concentration, this mother liquor is introduced the step that one-level chemical precipitation treatment system 1 processes.Avoid the mother liquor with high density scale-forming ion and corrosive ions and enter multiple-effect evaporation concentration and crystallization device, so avoid high density scale-forming ion can on evaporator room 8 heat transfer tube fouling and after affecting heat transfer, enrichment method the corrosive ions of high density can cause the generation of the phenomenons such as corrosion to evaporator room 8 heat transfer tube.
Further, the water of condensation that produced by multi-effect evaporating device is also comprised to the step entering the desulfurization wastewater before multi-effect evaporating device and carry out preheating.Thus namely desulfurization wastewater is removed scale-forming ion and corrosive ions before entering multi-effect evaporating device.
Preferably, the exhaust steam that multi-effect evaporating device adopts power station to send here, as heating steam, utilizes exhaust steam of electric power plant to carry out multiple-effect vacuum evaporating, concentrating and crystallizing to desulfurization wastewater, moisture in desulfurization wastewater is separated with salinity.Thus take full advantage of the heat energy of exhaust steam of electric power plant, save resource, avoid the waste of heat energy.
Further, described desulfurization wastewater enters the step that multi-effect evaporating device carries out evaporating:
Desulfurization wastewater advection enters multiple evaporating, concentrating and crystallizing devices of multi-effect evaporating device, the heating steam of first effect evaporating, concentrating and crystallizing device is provided by external steam source, the secondary steam that last effect produces enters next effect evaporating, concentrating and crystallizing device, dense salt slurry adopts and turns material mode, the mother liquor improving salinity through last effect enters next effect evaporating, concentrating and crystallizing device, and the mother liquor of end effect evaporating, concentrating and crystallizing device enters equipment for separating liquid from solid.
Further, in each effect evaporating, concentrating and crystallizing device, the water of condensation that heating steam is formed flows into level of condensation weighing apparatus bucket 9, the flash-off steam produced in water of condensation balance bucket 9 returns heating chamber 7, the utilization of condensed water water of condensation balance bucket 9 that last effect evaporating, concentrating and crystallizing device produces deliver to after collecting after an effect water of condensation balance bucket 9, deliver to next after imitating with rear one the water of condensation mixing shwoot some vapor that heating chamber 7 produces and imitate water of condensation and balance bucket 9.
Preferably, the water of condensation introducing preheater 5 that the water of condensation of end effect evaporating, concentrating and crystallizing device balances in bucket 9 carries out preheating to entering the desulfurization wastewater before multi-effect evaporating device.
Further, the steam of the evaporator room 8 of last effect evaporating, concentrating and crystallizing device enters vapour condensation device.
Further, the step that described desulfurization wastewater processes through one-level chemical precipitation treatment system 1 adopts existing routine techniques, generally comprises following steps: by desulfurization wastewater introduce in and case, in and case in add aqua calcis adjust ph, make Mg simultaneously 2+, Pb 2+, Cr 3+, Cd 2+plasma is precipitated out with hydroxide form, the F in waste water -ion is with CaF 2form settles, in and the waste water that completes reaction in case enter sludge box, and add organosulfur in sludge box, make remaining Pb 2+, Cr 3+, Cd 2+be precipitated out with sulphided form etc. heavy metal ion, the waste water completing reaction in sludge box enters flocculation tanks, flocculation agent chloro sulphuric acid iron is added and/or coagulant aids PAM makes throw out in conjunction with sedimentation in flocculation tanks, through flocculation tanks discharge waste water through settler clarification after, complete one-level chemical precipitation treatment system 1 and process.
The concentration of Controlling System internal corrosive ion and fouling tendency type ion is in two ways adopted in limits: 1 arranges multi-effect evaporating device mother liquor reflux pipe to front end chemical precipitation treatment system in treatment method; The mother liquor reflux that 2 equipment for separating liquid from solid produce is to chemical precipitation treatment system.
Adopt the system of described a kind of zero emission treatment of desulfured waste water, comprise set gradually for removing heavy metal ion and F in desulfurization wastewater -the one-level chemical precipitation treatment system 1 of ion, by adding Na 2cO 3solution is to remove the Ca in desulfurization wastewater 2+, Mg 2+ion also generates the secondary chemical precipitation process system of NaCl, multi-effect evaporating device and equipment for separating liquid from solid, also comprises the pipeline mother liquor in multi-effect evaporating device being introduced one-level chemical precipitation treatment system 1.
The present invention by adding Na in the waste water after chemical precipitation method process 2cO 3solution carries out second order reaction process, with CO 3 2-precipitation Ca wherein 2+, Mg 2+ion, reduces the Ca in water 2+, Mg 2+ionic concn, reduces the fouling tendency of desulfurization wastewater; Desulfurization wastewater to be changed into solute be NaCl is simultaneously main solution system.Desulfurization wastewater after second order reaction process, carry out multiple-effect vacuum evaporating, concentrating and crystallizing to it, moisture in desulfurization wastewater is separated with salinity, moisture is recycled, and produce the secondary industrial goods salt byproduct that main component is NaCl, realize the treatment system of desulfurization wastewater zero release.This treatment system is that the highly purified clear water of main generation is recycled, and produces the secondary industrial goods salt byproduct that main component is NaCl simultaneously, creates added value.
And the concentration of scale-forming ion in multi-effect evaporating device in mother liquor reach fouling concentration before or corrosive ions concentration reach corrosion heat transfer tube concentration before the partial mother liquid in multi-effect evaporating device is introduced one-level chemical precipitation treatment system 1, thus reduce the scale-forming ion of mother liquor and the concentration of corrosive ions in multiple-effect evaporation concentration and crystallization device, avoid the generation of fouling or corrosion.
One-level chemical precipitation treatment system 1 is the device adopting the traditional chemical precipitator method to carry out desulfurization wastewater process, for legacy equipment, its generally comprise and set gradually in and case, sludge box, flocculation tanks and primary-clarifiers, during desulfurization wastewater enters and after case, to in and case in add aqua calcis adjust ph, make Mg simultaneously 2+, Pb 2+, Cr 3+, Cd 2+plasma is precipitated out with hydroxide form, the F in waste water -ion is with CaF 2form settles, in and the waste water that completes reaction in case enter sludge box, and add organosulfur in sludge box, make remaining Pb 2+, Cr 3+, Cd 2+be precipitated out with sulphided form etc. heavy metal ion, the waste water completing reaction in sludge box enters flocculation tanks, in flocculation tanks, add flocculation agent chloro sulphuric acid iron, coagulant aids PAM makes throw out in conjunction with sedimentation, through flocculation tanks discharge waste water through primary-clarifiers clarification after, enter secondary chemical precipitation process system.
Described secondary chemical precipitation process system comprises the second order reaction case 2, Secondary clarifier 3 and the strainer 4 that set gradually.Na is added in second order reaction case 2 2cO 3solution is with CO 3 2-precipitation Ca wherein 2+, Mg 2+ion, reduces the Ca in water 2+, Mg 2+ionic concn, reduces the fouling tendency of desulfurization wastewater, and desulfurization wastewater to be changed into solute be NaCl is simultaneously main solution system, after Secondary clarifier 3 and strainer 4 remove precipitation, enter multi-effect evaporating device.
Described multi-effect evaporating device comprises multiple evaporating, concentrating and crystallizing device, and each evaporating, concentrating and crystallizing device is provided with the pipeline mother liquor of its inside being introduced one-level chemical precipitation treatment system 1.The steam of input is utilized repeatedly, the number of times that steam is utilized is called " effect number ", the heating steam of first effect is provided by external steam feeding mechanism, preferably, the heating steam of first effect is provided by exhaust steam of electric power plant, the secondary steam that last effect evaporation produces enters next effect evaporating, concentrating and crystallizing device, as the heating steam of next effect evaporating, concentrating and crystallizing device, by that analogy, steam is repeatedly utilized, the secondary steam that the evaporation of end effect evaporated crystallization device produces is delivered to end effect vapour condensation device and is cooled with circulating water formation vacuum, improves heat transfer temperature difference.Dense salt slurry adopts and turns material mode by effect, and namely first effect concentrated solution proceeds to two effects and again concentrates, and two effect concentrated solutions proceed to next effect, by that analogy.The salt slurries of end effect evaporating, concentrating and crystallizing device enter equipment for separating liquid from solid.Increase and decrease according to system processing power during middle effect evaporating, concentrating and crystallizing device quantitative design.
Described evaporating, concentrating and crystallizing device comprises heating chamber 7, recycle pump 6 and evaporator room 8, the water shoot of evaporator room 8 connects the water-in of recycle pump 6, the water port of recycle pump 6 connects the water inlet pipe of well heater, the water shoot of well heater connects the water inlet pipe of evaporator room 8, liquid in evaporator room 8 and well heater circulates under the effect of recycle pump 6, row's vapour pipe of evaporator room 8 connects the steam input pipe of the heating chamber 7 of next effect evaporating, concentrating and crystallizing device, the steam input pipe of the heating chamber 7 of first effect evaporating, concentrating and crystallizing device connects SS, the pipeline mother liquor of last effect evaporating, concentrating and crystallizing device being introduced next effect evaporating, concentrating and crystallizing device is provided with between adjacent two-effect evaporation concentration and crystallization device, the mother liquor vent pipe of end effect evaporating, concentrating and crystallizing device connects equipment for separating liquid from solid, the wastewater drainage pipe of secondary chemical precipitation process system is connected with each effect evaporating, concentrating and crystallizing device, wastewater drainage pipe is communicated with the water shoot of connection evaporator room 8 of each effect evaporating, concentrating and crystallizing device and the pipeline of the water-in of recycle pump 6.Make the desulfurization wastewater advection after second order reaction process enter often effect in multiple-effect evaporation concentration and crystallization device, namely often imitate in evaporator room 8 and all enter fresh desulfurization wastewater.
Heating chamber 7 is heat exchanger structure, and heating steam, after the steam input pipe of heating chamber 7 enters heating chamber 7, is carried out heat exchange with the liquid in heating chamber 7 pipeline, discharged Heat Room after being condensed into phlegma.Wastewater mother liquor circulates under the driving of recycle pump 6 in heating chamber 7 and evaporator room 8.
Desulfurization wastewater in evaporating, concentrating and crystallizing device forced circulation pump 6 act under pump circulation, desulfurization wastewater advection after the process of secondary chemical precipitation process system sends into each effect evaporating, concentrating and crystallizing device circulation tube, improves to enter after flow velocity to enter evaporator room 8 after heating chamber 7 heats up with steam heat-exchanging and carry out gas-liquid separation through forced circulation pump 6.
Described evaporating, concentrating and crystallizing device adopts pump circulation to improve circulation velocity, improves heat transfer coefficient, reduces facility investment, reduces heat transfer tube fouling tendency simultaneously.
Preferably, the steam that described multi-effect evaporating device adopts is the exhaust steam that power station produces, namely the head of multi-effect evaporating device imitates the exhaust steam vent pipe in the steam input pipe connection power station of the heating chamber 7 of evaporating, concentrating and crystallizing device, the exhaust steam that power station is sent here is delivered to first effect heating chamber 7 pairs of desulfurization wastewaters and is heated, the secondary steam that first effect evaporator room 8 produces imitates the thermal source of heating chamber 7 as next, the like.Utilize exhaust steam of electric power plant to carry out multiple-effect vacuum evaporating, concentrating and crystallizing to the desulfurization wastewater after second order reaction process, moisture in desulfurization wastewater is separated with salinity.Thus take full advantage of the heat energy of exhaust steam of electric power plant, save resource, avoid the waste of heat energy.
Described evaporating, concentrating and crystallizing device also comprises water of condensation balance bucket 9, the condensed water discharge pipe of heating chamber 7 connects water of condensation balance bucket 9, the water of condensation that heating steam is formed flows into level of condensation weighing apparatus bucket 9, water of condensation balance bucket 9 is provided with flash-off steam vent pipe, and flash-off steam vent pipe connects the steam input pipe of heating chamber 7.
Further, the water shoot of the water of condensation balance bucket 9 of last effect evaporating, concentrating and crystallizing device connects the water of condensation balance bucket 9 of a rear effect evaporating, concentrating and crystallizing device, thus a rear effect water of condensation balance bucket 9 delivered to by the utilization of condensed water water of condensation balance bucket 9 that last effect evaporating, concentrating and crystallizing device produces after collecting, deliver to next after imitating with rear one the water of condensation mixing shwoot some vapor that heating chamber 7 produces to imitate water of condensation and balance bucket 9, so circulate.
Preferably, described system also comprises a preheater 5, be connected with evaporating, concentrating and crystallizing device again after the liquid discharge pipe of secondary chemical precipitation process system connects this preheater 5, end effect evaporating, concentrating and crystallizing device water of condensation balance bucket 9 water shoot connect this preheater 5 by pipeline after connect condensed water bucket 14 again, thus by water of condensation, preheating is carried out to the desulfurization wastewater that secondary chemical precipitation process system is discharged, water of condensation after heat exchange flow to condensed water bucket 14 again and reclaims, thus take full advantage of the heat energy of water of condensation, namely take full advantage of the heat energy of heating steam.The water of condensation that condensed water bucket 14 is collected can be sent power plant back to and be recycled.
Described equipment for separating liquid from solid comprises the thickener 10 and whizzer 11 that set gradually, and thickener 10 is connected mother vat 12 with the liquid discharge tube of whizzer 11, and the liquid discharge pipe of mother vat 12 connects multiple-effect evaporation concentration and crystallization device.In multiple-effect evaporation concentration and crystallization device, the salt slurries of output deliver to suspension separation again in thickener 10, and the salt slurry recycling whizzer 11 after thickening carries out solid-liquid separation, and isolate solid salt and take out as Industrial Salt, isolated saline solution returns evaporation in evaporator room 8.
Preferably, the liquid discharge pipe of mother vat 12 also connects one-level chemical precipitation treatment system 1 by pipeline, before scale-forming ion concentration in mother vat 12 in mother liquor reaches fouling concentration or before corrosive ions concentration reaches corrosion heat transfer tube concentration, partial mother liquid in mother vat 12 is introduced one-level chemical precipitation treatment system 1, thus reduce the ionic concn of mother liquor in multiple-effect evaporation concentration and crystallization device, avoid the generation of fouling or corrosion.
Described system also comprises end effect vapour condensation device, and row's vapour pipe of the evaporator room 8 of the end effect evaporating, concentrating and crystallizing device of multi-effect evaporating device connects this end effect vapour condensation device, and the water of condensation liquid discharge pipe of end effect vapour condensation device connects condensed water bucket 14.Described end effect vapour condensation device is surface condenser 13, and preferably, surface condenser 13 is connected with a vacuum pump 15 vacuumized it, for non-condensable gas is emptying.
Utilize the present invention, for the desulfurization wastewater of different treatment amount, only need calculate required heat interchanging area, select suitable middle effect quantity to realize in conjunction with investment etc.
Multiple-effect vacuum evaporating, concentrating and crystallizing technology in this multiple-effect evaporation condensing crystal system adopts the concentration of Controlling System internal corrosive ion and fouling tendency type ion in two ways in limits: 1 arranges multi-effect evaporating device mother liquor reflux pipe to front end one-level chemical precipitation treatment system 1; The mother liquor reflux that 2 equipment for separating liquid from solid produce is to one-level chemical precipitation treatment system 1.
As mentioned above, the present invention can be realized preferably.

Claims (10)

1. a zero emission treatment of desulfured waste water, it is characterized in that, comprise the following steps: desulfurization wastewater is after one-level chemical precipitation treatment system (1) process, in desulfurization wastewater, add sodium carbonate react, then desulfurization wastewater is precipitated, send into multi-effect evaporating device after filtering to evaporate, the steam of evaporation output obtains water of condensation after heat exchange, the salt slurry of evaporation output enters equipment for separating liquid from solid and carries out solid-liquid separation, obtain solid salt, before in multi-effect evaporating device, the concentration of the scale-forming ion of mother liquor reaches fouling concentration or before corrosive ions concentration reaches corrosion heat transfer tube concentration, partial mother liquid in multi-effect evaporating device is introduced one-level chemical precipitation treatment system (1) process, this partial mother liquid is through the process of chemical precipitation treatment system, to reduce in mother liquor after scale-forming ion concentration and corrosive ions concentration, again enter multi-effect evaporating device to evaporate.
2. a kind of zero emission treatment of desulfured waste water according to claim 1, is characterized in that, also comprises mother liquor solid-liquid separation obtained and is introduced into the step that multi-effect evaporating device carries out evaporating.
3. a kind of zero emission treatment of desulfured waste water according to claim 1 and 2, it is characterized in that, before the scale-forming ion concentration being also included in the mother liquor that solid-liquid separation obtains reaches fouling concentration or before corrosive ions concentration reaches corrosion heat transfer tube concentration, this mother liquor is introduced the step that one-level chemical precipitation treatment system (1) processes.
4. a kind of zero emission treatment of desulfured waste water according to claim 1, is characterized in that, also comprises the water of condensation that produced by multi-effect evaporating device to the step entering the desulfurization wastewater before multi-effect evaporating device and carry out preheating.
5. a kind of zero emission treatment of desulfured waste water according to claim 1, is characterized in that, the exhaust steam that described multi-effect evaporating device adopts power station to send here is as heating steam.
6. a kind of zero emission treatment of desulfured waste water according to claim 1, it is characterized in that, described desulfurization wastewater enters the step that multi-effect evaporating device carries out evaporating: desulfurization wastewater advection enters multiple evaporating, concentrating and crystallizing devices of multi-effect evaporating device, the heating steam of first effect evaporating, concentrating and crystallizing device is provided by external steam source, the secondary steam that last effect produces enters next effect evaporating, concentrating and crystallizing device, dense salt slurry adopts and turns material mode, the mother liquor improving salinity through last effect enters next effect evaporating, concentrating and crystallizing device, the mother liquor of end effect evaporating, concentrating and crystallizing device enters equipment for separating liquid from solid.
7. a kind of zero emission treatment of desulfured waste water according to claim 6, it is characterized in that, in each effect evaporating, concentrating and crystallizing device, the water of condensation that heating steam is formed flows into level of condensation weighing apparatus bucket (9), the flash-off steam produced in water of condensation balance bucket (9) returns heating chamber (7), utilization of condensed water water of condensation balance bucket (9) that last effect evaporating, concentrating and crystallizing device produces deliver to after collecting after effect water of condensation balance bucket (9), deliver to next after imitating with rear one the water of condensation mixing shwoot some vapor that heating chamber (7) produces and imitate water of condensation and balance bucket (9).
8. a kind of zero emission treatment of desulfured waste water according to claim 7, it is characterized in that, the water of condensation in water of condensation balance bucket (9) of end effect evaporating, concentrating and crystallizing device is introduced preheater (5) and is carried out preheating to entering the desulfurization wastewater before multi-effect evaporating device.
9. a kind of zero emission treatment of desulfured waste water according to claim 7, is characterized in that, the steam of the evaporator room (8) of last effect evaporating, concentrating and crystallizing device enters vapour condensation device.
10. a kind of zero emission treatment of desulfured waste water according to claim 1, it is characterized in that, the step that described desulfurization wastewater processes through one-level chemical precipitation treatment system (1) is in introducing desulfurization wastewater and case, to in and case in add aqua calcis, in and the waste water that completes reaction in case enter sludge box, and organosulfur is added in sludge box, the waste water completing reaction in sludge box enters flocculation tanks, flocculation agent is added or coagulant aids makes throw out in conjunction with sedimentation in flocculation tanks, through flocculation tanks discharge waste water through settler clarification after, complete one-level chemical precipitation treatment system (1) process.
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