阅读说明：本技术 一种煤化工酚类废水等离子体氧化沉积制取碳酸纳方法 (Method for preparing sodium carbonate by plasma oxidation deposition of coal chemical industry phenol wastewater ) 是由 苏国贤 周霞萍 刘冀生 于 2020-12-22 设计创作，主要内容包括：一种煤化工酚类废水等离子体氧化沉积制取碳酸纳方法,目的是含酚废水除酚后循环利用,提升产品附加值；本发明将煤焦油中混合酚油从煤焦油馏分塔酚油侧线馏出,进入洗涤塔用氢氧化钠溶液洗涤,形成酚钠盐在洗涤塔连续排出到酚钠盐中间槽；再利用烟气中二氧化碳弱酸性,经冷凝冷却、油水分离后形成粗酚油层和废水层；粗酚油层分离后再去多侧线精馏塔分离成苯酚、甲酚等；废水层分离后加入石灰水反应形成饱和碳酸钙、碳酸氢钙从冷凝冷却罐中沉淀析出到回收罐；分离出相交层含少量杂酚的废水；将回收的含少量杂酚的废水放在反应罐中,采用低温等离子体反应器通过激发放电产生磁场将水中的碳酸钠分步氧化成过碳酸钠和碳酸氢钠,再还原成碳酸钠。(A method for preparing sodium carbonate by plasma oxidation and deposition of phenol wastewater in coal chemical industry, aiming at recycling phenol-containing wastewater after phenol removal and improving the added value of products; the method comprises the steps of distilling mixed phenol oil in coal tar from a phenol oil side line of a coal tar distillate tower, washing the mixed phenol oil in a washing tower by using a sodium hydroxide solution to form sodium phenolate, and continuously discharging the sodium phenolate in the washing tower to a sodium phenolate intermediate tank; then, utilizing weak acidity of carbon dioxide in the flue gas, and forming a crude phenol oil layer and a waste water layer after condensation cooling and oil-water separation; separating the crude phenol oil layer, and separating into phenol, cresol, etc. in a multi-side-line rectifying tower; after the wastewater layer separation, adding lime water to react to form saturated calcium carbonate and calcium bicarbonate, precipitating from a condensation cooling tank, and separating to a recovery tank; separating the waste water containing a small amount of the impure phenol in the intersecting layer; the recovered waste water containing a small amount of the impure phenol is placed in a reaction tank, and a low-temperature plasma reactor is adopted to generate a magnetic field by exciting discharge so as to oxidize sodium carbonate in the water into sodium percarbonate and sodium bicarbonate step by step and then reduce the sodium percarbonate.)

1. A method for preparing sodium carbonate by coal chemical industry phenol wastewater plasma oxidation deposition is characterized by comprising the following steps:

(1) distilling off mixed phenol oil in coal tar from a phenol oil side line of a coal tar distillate tower, feeding the distilled mixed phenol oil into a washing tower, continuously washing the distilled mixed phenol oil by adopting a sodium hydroxide solution with the mass percentage concentration of 7-15%, and continuously reacting and washing the washed mixed phenol oil from top to bottom by the sodium hydroxide solution to form a sodium phenolate salt, and continuously discharging the sodium phenolate salt to a sodium phenolate salt intermediate tank at the lower part of the washing tower;

(2) decomposing sodium phenolate by using weak acidity of carbon dioxide in flue gas through a pipeline type flue gas waste gas tower, and forming a crude phenol oil layer and a wastewater layer containing phenol, sodium hydroxide, sodium carbonate and sodium bicarbonate after passing through a condensation cooling tank and an oil-water separator; separating the crude phenol oil layer, and separating into phenol, cresol, xylenol, trimethylphenol and naphthol in a multi-side line rectifying tower;

(3) after separating the wastewater layer containing phenol, sodium hydroxide, sodium carbonate and sodium bicarbonate, adding lime water with the mass percentage concentration of 15-55% at the speed of 0.3-1.0 ton/h to ensure that the sodium carbonate and the sodium bicarbonate in the wastewater layer react to form saturated calcium carbonate and calcium bicarbonate to precipitate and separate out from a condensation cooling tank to a recovery tank; separating waste water containing a small amount of impure phenol in an intersecting layer according to the insolubility of oil and water, wherein the residual sodium hydroxide aqueous solution can be recycled;

(4) the recovered waste water containing a small amount of the impure phenol is placed in a reaction tank, a low-temperature plasma reactor is adopted to generate a magnetic field through exciting discharge, hydrogen peroxide plasma is generated, a small amount of the impure phenol in the waste water is removed, sodium carbonate in the water is oxidized and hydrogenated into sodium percarbonate and sodium bicarbonate step by step, the sodium percarbonate is reduced into the sodium carbonate under the action of part of recycled sodium hydroxide, and the high-purity sodium carbonate is prepared through evaporation, drying and dehydration.

2. The method for preparing sodium carbonate by the plasma oxidation and deposition of the phenol wastewater in the coal chemical industry according to claim 1, wherein the wastewater containing a small amount of the impure phenol in the intersecting layer is separated, the phenol with the mass percentage concentration of 0.01-5.0mg/L is contained, the unsaturated sodium carbonate with the mass percentage concentration of 0.10-7.50% and the sodium bicarbonate with the mass percentage concentration of 0.10-5.00% are collected into the reaction tank again after the saturated calcium carbonate is separated out.

3. The method for preparing sodium carbonate by the plasma oxidation deposition of the coal chemical industry phenol wastewater as claimed in claim 1 or 2, characterized in that the wastewater containing a small amount of the impure phenol has a mass content ratio of phenol, cresol, xylenol, trimethylphenol and naphthol of 0-48: 0-30: 0-15: 0-5: 0-2.

4. The method for preparing sodium carbonate by the plasma oxidation deposition of the coal chemical industry phenol wastewater as claimed in claim 1 or 2, characterized in that the low-temperature plasma reactor is a model HPD-680 glow discharge low-temperature plasma reactor, the power of a high-frequency low-voltage power supply is 1-10KW, the temperature is controlled to be 0-50 ℃, and the pressure is 0.10-0.11 MPa.

Technical Field

The invention relates to a method for preparing sodium carbonate by using coal chemical industry phenol wastewater through plasma oxidation.

Background

The phenol pollutants belong to prototype toxicants, are toxic to human bodies and have durability in the environment. The treatment of phenol-containing wastewater is always an important challenge for industrial water. Common methods comprise Fenton oxidation sodium persulfate activation oxidation, ozone oxidation, oxidation of graphene oxide-based water treatment materials, plasma oxidation and the like. Among them, graphene oxide-based water treatment materials and plasma treatment are in the paper report stage. The invention just disclosed relates to an environment-friendly low-energy-consumption treatment method for refining wastewater containing sodium sulfate and phenol by tar, which comprises the steps of separating oil by gravity, performing air floatation on the wastewater, performing coke filtration on the wastewater by using a precision filter, performing freeze crystallization, performing re-centrifugation, performing reverse dissolution, evaporating, dehydrating and drying to obtain high-purity sodium sulfate in sewage. However, the method has the defects of long treatment time, low added value of sodium sulfate and the like. Publication name: the Water, Air, & Soil Pollution, 2018, vol.229 (10), pp.1-12 reports a novel gas-liquid two-phase dielectric barrier discharge plasma reactor designed by research of environmental science and engineering academy of east China university, institute of Pollution control and ecological safety in Shanghai city, Zhang culvert of Paris miracle Institute (IRCP), Liu ya nan, Cheng Rubia, Zhang Ailing, Li Xiang, Liu jin Xia Shi Jie, Yang Cheng, St phanid Ogner, Panli and the like, and is used for removing phenol in aqueous solution. The influence of operating conditions (applied voltage, discharge spacing, pH value and conductivity), different water matrixes (deionized water, underground water, surface water and tap water) and inorganic ions on the water matrixes is examined, and a possible degradation path is provided through GC-MS measurement. Is now in the development stage. Publication name: korean Journal of Environmental Health2012-06-01 reported the applicability of Korea 김동석, 박영식 et al scholars to the treatment of refractory wastewater such as phenol using the circulating dielectric barrier plasma (DBD) method. The researched DBD plasma reactor system consists of a plasma reactor (a discharge electrode, a grounding electrode, a quartz medium tube and an outer tube), a high-voltage power supply, a gas source and a gas storage tank. The influence of the initial voltage (60-180V), the oxygen supply rate (0.5-3L/min), the liquid circulation rate (1.5-7L/min), the pH value (3.02-11.06) and the initial phenol concentration (12.5-100 mg/L) on phenol degradation and UV254 absorbance is investigated. As a result: the experimental results show that the optimal initial voltage, oxygen supply rate and liquid circulation rate for phenol degradation are 160v, 1l/min and 4.5l/min, respectively. The removal rate of phenol increased with the increase of the initial pH of the phenol solution. In order to achieve a phenol and COD removal rate of 97% or more (initial phenol concentration of 50.0 mg/l), 15min and 180min were required, respectively. Because the system adopts the absorbance of UV254 to phenol degradation, the absorbance can be used as an indirect index of the change of non-biodegradable organic matters. The mineralization time of phenol solutions can be longer than the time required for phenol degradation and is not suitable for large-scale water treatment. The plasma is a fourth state out of solid, liquid and gas states. The plasma obtained by using low-pressure discharge method and radiation and heat conduction method can make a series of chemical reactions, so that it is worth extensively researching and applying.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide the method for preparing sodium carbonate by the plasma oxidation deposition of the phenol wastewater in the coal chemical industry, which can recycle the phenol-containing wastewater after phenol removal and improve the added value of products.

The method of the invention comprises the following steps:

(1) distilling off mixed phenol oil in coal tar from a phenol oil side line of a coal tar distillate tower, feeding the distilled mixed phenol oil into a washing tower, continuously washing the distilled mixed phenol oil by adopting a sodium hydroxide solution with the mass percentage concentration of 7-15%, and continuously reacting and washing the washed mixed phenol oil from top to bottom by the sodium hydroxide solution to form a sodium phenolate salt, and continuously discharging the sodium phenolate salt to a sodium phenolate salt intermediate tank at the lower part of the washing tower;

(2) decomposing sodium phenolate by using weak acidity of carbon dioxide in flue gas through a pipeline type flue gas waste gas tower, and forming a crude phenol oil layer and a wastewater layer containing phenol, sodium hydroxide, sodium carbonate and sodium bicarbonate after passing through a condensation cooling tank and an oil-water separator; separating the crude phenol oil layer, and separating into phenol, cresol, xylenol, trimethylphenol and naphthol in a multi-side line rectifying tower;

(3) separating water layer containing phenol, sodium hydroxide, sodium carbonate and sodium bicarbonate, adding lime water with mass percent concentration of 15-55%, and adding at a speed of 0.3-1.0 ton/h to react sodium carbonate solution therein to form saturated calcium carbonate, and precipitating calcium bicarbonate out of a condensation cooling tank to a calcium carbonate recovery tank; the intersecting layer of a small amount of the impure phenol and water is used as wastewater to be separated and recycled, the wastewater containing a small amount of the impure phenol in the intersecting layer is separated again according to the insolubility of oil and water, and the residual sodium hydroxide aqueous solution can be recycled; so that the sodium hydroxide with the mass percentage concentration of 80.0-87.5 percent can be recycled (the reaction formula is NaCO3+ CaO + H2O → NaOH + CaCO 3);

(4) the recovered waste water containing a small amount of the impure phenol is placed in a reaction tank, and also contains low phenol with the mass percentage concentration of 0.01-5.0mg/L, sodium carbonate with the mass percentage concentration of 0.10-7.50% and sodium bicarbonate with the mass percentage concentration of 0.10-5.00%, a low-temperature plasma reactor is adopted to generate a magnetic field by exciting discharge, hydrogen peroxide plasma is generated, a small amount of the impure phenol in the waste water is removed, the sodium carbonate in the water is oxidized and hydrogenated step by step to form sodium percarbonate and sodium bicarbonate, the sodium carbonate is reduced to form the sodium carbonate under the action of 0.2-2.0% recycled sodium hydroxide, and the high-purity sodium carbonate is prepared by evaporation, drying and dehydration.

The low-temperature plasma reactor adopts a glow discharge model HPD-680 low-temperature plasma reactor, and is produced by Nanjing Suman plasma technology Limited. The power of the high-frequency low-voltage power supply is 1-10KW, the temperature is controlled to be 0-50 ℃, and the pressure is controlled to be 0.10-0.11 MPa. The magnetic field effect is generated by exciting discharge, and the computer program output shows that the removal rate of phenols can reach 99.0-99.8% through ICP-MS inspection in the continuous treatment process at 1-15 sec.

Separating out the wastewater containing a small amount of impure phenol in the intersecting layer, wherein the wastewater contains 0.01-5.0mg/L of phenol in mass percent and unsaturated sodium carbonate in mass percent of 0.10-7.50% and sodium bicarbonate in mass percent of 0.10-5.00% which are converged into the reaction tank again after the saturated calcium carbonate is separated out. The waste water containing a small amount of the impure phenol contains 0.01-5.0mg/L of phenol mass concentration, wherein the mass content ratio of phenol, cresol, xylenol, trimethylphenol and naphthol is 0-48: 0-30: 0-15: 0-5: 0-2.

In order to recycle the sodium hydroxide, lime is added into the non-volatile fraction at the bottom of the tower to recover the sodium hydroxide. Namely: NaCO3+ CaO + H2O → NaOH + CaCO3, the recovery rate of sodium hydroxide is generally 80.0-87.5%;

the method comprises the steps of oxidizing sodium carbonate in water into sodium percarbonate, 2Na2CO3+3H2O2 → 2Na2C03.3H202, reducing 2Na2C03.3H202 → 2Na2CO3+3H2O2 by removing phenol, cresol and xylenol in wastewater through low-temperature plasma oxidative degradation with a hydrogen peroxide additive and under the condition of removing the phenol, the cresol and the xylenol in the wastewater through a low-temperature plasma reactor, and enriching, drying and dehydrating by adopting a paddle type evaporation drying tank of a Centendol drying equipment Limited company.

The method is suitable for recycling phenol in coal chemical industry, has simple and reliable process, can recycle phenol-removed water, turns sodium carbonate into products, recycles the sodium carbonate in phenol process wastewater, and creates higher added value than the sodium sulfate in the prior art.

Detailed Description

A more specific method comprises the following steps:

(1) distilling out mixed phenol oil containing phenol, cresol, xylenol, trimethylphenol, naphthol and the like in coal tar in a coal tar coking process from a phenol oil side line of a coal tar distillate tower, feeding the mixed phenol oil into a washing tower, continuously washing by adopting a sodium hydroxide solution with the mass percentage concentration of 7-15%, and continuously reacting and washing with the mixed phenol oil from top to bottom by the sodium hydroxide solution to form a sodium phenolate salt, and continuously discharging the sodium phenolate salt to a sodium phenolate salt intermediate tank at the lower part of the washing tower;

(2) decomposing phenolic sodium salt by a pipeline type flue gas and waste gas tower of a coal tar mixed phenolic fraction tower, and forming a crude phenolic oil layer and a waste water layer containing phenol, sodium hydroxide, sodium carbonate and sodium bicarbonate after passing through a condensation cooling tank and an oil-water separator; separating the crude phenol oil layer, and separating into phenol, cresol, xylenol, trimethylphenol and naphthol in a multi-side line rectifying tower;

(3) separating water layer containing phenol, sodium hydroxide, sodium carbonate and sodium bicarbonate, adding lime water with mass percent concentration of 15-55%, and adding at a speed of 0.3-1.0 ton/h to react sodium carbonate solution therein to form saturated calcium carbonate, and precipitating calcium bicarbonate out of a condensation cooling tank to a calcium carbonate recovery tank; the intersecting layer of a small amount of the impure phenol and water is used as wastewater to be separated and recycled, the wastewater containing a small amount of the impure phenol in the intersecting layer is separated again according to the insolubility of oil and water, and the residual sodium hydroxide aqueous solution can be recycled; so that the sodium hydroxide with the mass percentage concentration of 80.0-87.5 percent can be recycled (the reaction formula is NaCO3+ CaO + H2O → NaOH + CaCO 3);

(4) the recovered waste water containing a small amount of the impure phenol is placed in a reaction tank, and also contains low phenol with the mass percentage concentration of 0.01-5.0mg/L, sodium carbonate with the mass percentage concentration of 0.10-7.50% and sodium bicarbonate with the mass percentage concentration of 0.10-5.00%, a low-temperature plasma reactor is adopted to generate a magnetic field by exciting discharge, hydrogen peroxide plasma is generated, a small amount of the impure phenol in the waste water is removed, the sodium carbonate in the water is oxidized and hydrogenated step by step to form sodium percarbonate and sodium bicarbonate, the sodium carbonate is reduced to form the sodium carbonate under the action of 0.2-2.0% recycled sodium hydroxide, and the high-purity sodium carbonate is prepared by evaporation, drying and dehydration.

The evaporation drying process adopts a blade type evaporation drying tank of Centantedandelin-free drying equipment limited company. The high-purity sodium carbonate (Na 2CO 3) product with the purity of 97.0 percent is prepared by enrichment, drying and dehydration.