CN101157504B - Process for softening hardwater by employing SO2 and CO2 in exhaust gas - Google Patents

Process for softening hardwater by employing SO2 and CO2 in exhaust gas Download PDF

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Publication number
CN101157504B
CN101157504B CN2007100357714A CN200710035771A CN101157504B CN 101157504 B CN101157504 B CN 101157504B CN 2007100357714 A CN2007100357714 A CN 2007100357714A CN 200710035771 A CN200710035771 A CN 200710035771A CN 101157504 B CN101157504 B CN 101157504B
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China
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water
softening
gas
tail gas
hard water
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Expired - Fee Related
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CN2007100357714A
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Chinese (zh)
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CN101157504A (en
Inventor
李立清
叶华
宋剑飞
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Central South University
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Central South University
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Abstract

A process for softening hard water with SO2 and CO2 contained in exhaust gas comprises: allowing the SO2 and the CO2 contained in the exhaust gas to react with the hard water; stopping the reaction when the pH of the mixed solution is tested to be 2.5-3.3; adjusting the pH of the mixed solution after reaction with alkaline solution to be 6.5-7.5; performing filtration to obtain softened water andfilter residue. The hard water contains 0.6-0.7g/L of Ca<2+> and 50-100mg/l of Mg<2+> and the pH thereof is 9-11; the volume concentrations of the sulfur dioxide and the carbon dioxide in the exhaustgas are respectively 1-10 percent and 5-30 percent. The invention overcomes the defect of high cost of the prior hard water softening art and provides a novel process with the excellent effect of treating the waste with another and saving the cost.

Description

Utilize SO in the tail gas 2, CO 2The technology of softening of water
Technical field
The invention belongs to field of environment protection, be specifically related to a kind of SO in the tail gas that utilizes 2, CO 2The novel process of softening of water.
Background technology
Coloured enterprise can often produce calcic purifying waste water about 1000mg/L in the wastewater treatment operation, and this purifying waste water owing to the hardness height, it is limited that its reuse is worth, and for realizing recycling economy, trade effluent " zero release " need be prepared to implement by enterprise.For guaranteeing waste water zero emission, at first must reduce this and purify water hardness.
And at present, the water softening method is mainly contained heated and boiled method, medicament tenderizer, ion exchange method, absorption method, distillation, reverse osmosis etc. both at home and abroad.These methods mainly are that raw material or energy expenditure are big, and cost is higher, all have much room for improvement, and innovation.
Summary of the invention
Technical problem to be solved by this invention is to overcome the existing high deficiency of water softening processing cost, provides a kind of novel process, the novel process of reach " treatment of wastes with processes of wastes against one another ", saving cost.
The technical scheme that the present invention solves the problems of the technologies described above employing is:
To contain SO 2, CO 2Tail gas and hard water react in the absorption tower, and when the pH of detection reaction mixed solution was 2.5-5.5, stopped reaction filtered reacted mixed solution, obtains softening water and filter residue; Described hard water is for containing Ca 2+Concentration 0.6-0.7g/L, pH is the solution of 9-11, contains SO 2, CO 2Sulfurous gas and carbonic acid gas volumetric concentration are respectively 1-10%, 5-30% in the tail gas.
Described hard water also contains Mg 2+Concentration 50-100mg/l.
It is 6.5-7.5 that reacted mixed solution is adjusted the pH value with alkali lye, filters then, obtains softening water and filter residue.
Liquid-gas ratio in the absorption tower is controlled at 2-3l/m 3
The production principle of sulfurous gas, carbonic acid gas softening of water:
SO 2+H 2O→H 2SO 3→H ++HSO 3 -→2H ++SO 3 2-
CO 2+H 2O→H 2CO 3→H ++HCO 3 -→2H ++CO 3 2-
Ca 2++SO 3 2-→CaSO 3
Ca 2++CO 3 2-→CaCO 3
Mg 2++SO 3 2-→MgSO 3
Mg 2++CO 3 2-→MgCO 3
SO 2+CaCO 3→CaSO 3+CO 2
SO 2+MgCO 3→MgSO 3+CO 2
2CaSO 3+O 2+4H 2O→2CaSO 4·2H 2O
2MgSO 3+O 2→2MgSO 4
The present invention is a kind of SO in the tail gas that utilizes 2, CO 2The novel process of softening of water.The reaction of sulfurous gas and hard water generates SO in the tail gas 3 2-, SO 3 2-With Ca 2+And Mg 2+Reaction generates calcium sulfite and magnesium sulfite precipitation respectively; Carbonic acid gas and hard water react in the tail gas, and then generate CO 3 2-, CO 3 2-With Ca 2+And Mg 2+Reaction generates lime carbonate and magnesiumcarbonate precipitation respectively; Lime carbonate and sulfurous gas reaction generate calcium sulfite.Adopt reverse gas-liquid washing in the reaction process, wash temperature: normal temperature; Reaction end pH value (outlet pH value): 2.5-5.5; A filtered liquid is for removing Ca 2+, Mg 2+Scavenging solution, i.e. softening water; Filter residue is calcium sulfite, calcium sulfate, lime carbonate, magnesium sulfite, sal epsom and magnesiumcarbonate precipitation.
Beneficial effect of the present invention is:
1. provide a new processing method for softening of water.
2. preferably resolve the unmanageable problem of sulfurous gas in water softening cost height and the tail gas.
3. technology of the present invention " treatment of wastes with processes of wastes against one another " has not only solved the problem of off gas treatment and water softening, has significant environmental benefit, economic benefit and social benefit.
Description of drawings
Fig. 1 is the process flow sheet of the embodiment of the invention 1
Embodiment
Embodiment 1:
With reference to accompanying drawing 1, earlier with finite concentration hard water (Ca 2+400mg/L; Mg 2+100mg/L) be sent in the bubble absorbing tower.Utilizing sulfur dioxide liquid preparation sulfur dioxide concentration is 1% gas, and gas flow is about 20Nm 3/ h blasts a bubble absorbing tower (tower diameter Φ 200mm, tower height 1m) by control valve control then, because pneumatic blending can be avoided suspended substance sedimentation.Be reflected at normal pressure, carry out under the condition of normal temperature, the tail gas behind the absorption reaction is discharged via the top on absorption tower.Behind the Gas-Liquid Absorption 1min, the pH value is 3, adjusts absorption liquid pH value to 7 with alkali lye, gets suspension.The settling pool solid-liquid separation, sedimentation time is 30min, filtrate is softening water, Ca 2+Be 18mg/L; Mg 2+Be 10mg/L.
The monitoring analysis report shows: SO before this factory's desulfurization is handled 2Volumn concentration be 1%, after handling through desulfurization, SO 2Volumn concentration is reduced to 0.01%, and desulfurization degree reaches more than 90%.
Embodiment 2:
Earlier with finite concentration hard water (Ca 2+1000mg/L), disposable being sent in the spray absorber.From certain factory's pipeline tail gas, draw discharge capacity and be about 200m N 3The branch road of/h, use earlier the sack cleaner dedusting, blast a bubble absorbing tower (tower diameter Φ 400m by control valve control then, tower height 3m), absorption tower bottom liquid (hard water) is extracted circulation out with pump and is sent into from the top, because water pump is extracted out continuously, sends into, bottom liquid is stirred, and avoids suspended substance sedimentation.Liquid-gas ratio is controlled at 2-3l/m 3About.At normal pressure, temperature of reaction is under the condition of normal temperature, sprays reaction, and the tail gas behind the absorption reaction is discharged via the top on absorption tower.Behind the Gas-Liquid Absorption 1min, the pH value is 3, adjusts absorption liquid pH value to 7 with alkali lye, gets suspension.The settling pool solid-liquid separation, sedimentation time is 30min, filtrate is softening water.Ca 2+Be 18mg/L; Mg 2+Be 10mg/L.
The monitoring analysis report shows: SO before this factory's desulfurization is handled 2Volumn concentration be 1%, after handling through desulfurization, SO 2Volumn concentration is reduced to 0.01%, and desulfurization degree reaches more than 90%.CO 2Volumn concentration is 14%, after handling through the washing decalcification, and CO 2Volumn concentration is reduced to 5.6%, CO 2Decreasing ratio reaches about 60%.

Claims (4)

1. utilize SO in the tail gas 2, CO 2The technology of softening of water is characterized in that, will contain SO 2, CO 2Tail gas and hard water react in the absorption tower, and when the pH of detection reaction mixed solution was 2.5-5.5, stopped reaction filtered reacted mixed solution, obtains softening water and filter residue; Described hard water is for containing Ca 2+Strength of solution 0.6-0.7g/L, pH is 9-11, sulfurous gas and carbonic acid gas volumetric concentration are respectively 1-10%, 5-30% in the tail gas.
2. according to claim 1ly utilize SO in the tail gas 2, CO 2The technology of softening of water is characterized in that, described hard water also contains Mg 2+Concentration is 50-100mg/L.
3. according to claim 1ly utilize SO in the tail gas 2, CO 2The technology of softening of water is characterized in that, it is 6.5-7.5 that reacted mixed solution is adjusted the pH value with alkali lye, filters then, obtains softening water and filter residue.
4. according to claim 1ly utilize SO in the tail gas 2, CO 2The technology of softening of water is characterized in that, the liquid-gas ratio in the absorption tower is controlled at 2-3L/m 3
CN2007100357714A 2007-09-19 2007-09-19 Process for softening hardwater by employing SO2 and CO2 in exhaust gas Expired - Fee Related CN101157504B (en)

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CN101157504B true CN101157504B (en) 2010-06-09

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Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102091516A (en) * 2010-12-06 2011-06-15 李在水 De-scaling and anti-scaling device by using smoke
CN103570144B (en) * 2012-12-28 2015-09-23 青岛啤酒股份有限公司 The carbonic acid gas utilizing dress wine machine to arrange outward stops the method for bottle washing machine fouling
CN103553246A (en) * 2013-11-21 2014-02-05 武汉森泰环保工程有限公司 Device and method for softening hard water by using carbon dioxide in flue gas
CN103752155A (en) * 2013-12-31 2014-04-30 上海宝钢磁业有限公司 Method for spraying and neutralizing by wastewater generated in pure water preparation
CN104291452B (en) * 2014-07-02 2016-10-19 中国石油天然气集团公司 Flue gas hardness removing device and using method thereof
CN109534537A (en) * 2018-11-20 2019-03-29 常州大学 A kind of gas heater waste gas utilization device for softened water

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4085194A (en) * 1972-05-08 1978-04-18 Hitachi, Ltd. Waste flue gas desulfurizing method
CN1066833A (en) * 1992-04-04 1992-12-09 淄博市周村水处理设备厂 Make the equipment of trade effluent dealkalize with sulfurous gas

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4085194A (en) * 1972-05-08 1978-04-18 Hitachi, Ltd. Waste flue gas desulfurizing method
CN1066833A (en) * 1992-04-04 1992-12-09 淄博市周村水处理设备厂 Make the equipment of trade effluent dealkalize with sulfurous gas

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
JP特开2005-161224A 2005.06.23
JP特开2007-209942A 2007.08.23

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