CN109939560B - Method and device for treating sulfur-containing flue gas - Google Patents

Method and device for treating sulfur-containing flue gas Download PDF

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CN109939560B
CN109939560B CN201711391749.3A CN201711391749A CN109939560B CN 109939560 B CN109939560 B CN 109939560B CN 201711391749 A CN201711391749 A CN 201711391749A CN 109939560 B CN109939560 B CN 109939560B
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flue gas
microalgae
gas
desulfurization
filtrate
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CN109939560A (en
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赵磊
师文静
刘忠生
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Sinopec Dalian Petrochemical Research Institute Co ltd
China Petroleum and Chemical Corp
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China Petroleum and Chemical Corp
Sinopec Dalian Research Institute of Petroleum and Petrochemicals
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Abstract

The invention relates to a method and a device for treating sulfur-containing flue gas, wherein the flue gas is introduced into a desulfurization reactor, and olefin waste lye is used as an absorbent to obtain the desulfurization flue gas and desulfurization waste liquor; causticizing and regenerating the desulfurization waste liquid to obtain a precipitate, and calcining at high temperature to obtain high-concentration SO2Reacting with the desulfurized flue gas to prepare sulfur; introducing the generated gas into a photobioreactor for microalgae culture, and collecting exhaust gas; carrying out solid-liquid separation on the culture system, and respectively harvesting microalgae cells and filtrate; adding sodium peroxide into the filtrate, and introducing exhaust gas into the filtrate for reaction to obtain purified gas; and performing denitrification treatment on the filtrate after the oxidation treatment. The invention combines olefin waste alkali liquid treatment and microalgae culture to treat SO-containing substances2、CO2、NOXThe flue gas realizes the high-efficiency treatment of the flue gas, and has the advantages of good removal effect, low treatment cost, economy, environmental protection and the like.

Description

Method and device for treating sulfur-containing flue gas
Technical Field
The invention belongs to the technical field of flue gas treatment, and particularly relates to a method and a device for treating sulfur-containing flue gas.
Background
Nitrogen oxides (NOx) having N2O、NO、NO2、N2O3、N2O4And N2O5And the like, and can cause various hazards, such as photochemical smog generated by Volatile Organic Compounds (VOC) in the atmosphere, strong stimulation to eyes and throat, headache, respiratory diseases and the like, and serious patients can causeCausing death. The NOx emission amount of China continuously exceeds 2000 ten thousand tons for years, and although the NOx emission amount has continuously reduced trend since 2012, the pollution condition is still serious. SO of China since 20032The total discharge amount is always high, and the SO in China is still high in 20142The total discharge amount is 1974.4 ten thousand tons. 9/12/2014, United release about printing<Coal-electricity energy-saving emission-reducing upgrade and transformation action plan (2014-2020)>Notification of (correction energy [ 2014)]2093), the ultra-clean emission of the flue gas of the coal burning boiler is required, namely, the smoke dust and SO2And NOx emission concentration index respectively reaches 10mg/Nm3、35mg/Nm3And 50mg/Nm3
The existing flue gas denitration technology mainly comprises the following steps: SCR (selective catalytic reduction) and SNCR (selective non-catalytic reduction) for gas phase reaction, liquid absorption, solid adsorption, high-energy electron activation oxidation (EBA electron beam irradiation and PPCP pulsed corona plasma), and the like. Among various flue gas denitration treatment technologies, a liquid absorption method has low denitration efficiency; the adsorption method has high denitration efficiency, but has small adsorption quantity, frequent regeneration and not wide application; the high-energy electronic activation oxidation method can realize desulfurization and denitrification at the same time, but has high energy consumption and short service life; the SNCR method has a high escape rate of ammonia, and causes a safety problem. Compared with other technologies, the SCR technology has the advantages of high denitration efficiency, mature technology and the like, and is the most applied technology in the flue gas denitration engineering at home and abroad at present. The SCR method is to use NH at the reaction temperature of 200 ℃ and 400 DEG C3Catalytic reduction of NOx to N as a reducing agent2Oxygen in the exhaust gas rarely participates in the reaction, and the heat release is small. However, the technology has high requirements on the catalyst, and the development of the high-performance catalyst is a research hotspot.
The common flue gas desulfurization methods mainly comprise a dry method and a wet method, and compared with the dry method, the wet method desulfurization method has the advantages of small equipment, simple operation, high desulfurization efficiency and wide application, such as a sodium method, a magnesium method, an ammonia method, a calcium method and the like, wherein the sodium method and the calcium method are the most. Wet desulfurization can be divided into a discarding method and a recycling method according to whether the product is useful, the recycling method used at present is a limestone-gypsum method, but the added value of the by-product gypsum is low and is over-demand, and meanwhile, the limestone-gypsum method is easy to cause scaling and blockage of equipment or pipelines, the operation of a desulfurization device is complicated, and the field sanitary condition is poor. Although the sulfur resource in the flue gas can be recovered by ammonia desulfurization, the product ammonium sulfate can harden the soil, which is rarely used alone, and heavy metal ions in the flue gas also completely enter the ammonium sulfate product, so that the secondary pollution is caused to the soil, and the health of human is further harmed. The sodium method flue gas desulfurization is a abandoning method, but is frequently adopted in areas with higher requirements on environmental protection indexes due to high absorption efficiency and high absorption rate. The concentration of sodium sulfite in the flue gas desulfurization wastewater by the sodium method is usually about 7.5-20%, and in order to ensure that the desulfurization wastewater can meet the emission requirement, when a flue gas desulfurization device is built, a flue gas desulfurization wastewater oxidation treatment device must be built at the same time. Because the oxidation rate of sodium sulfite is slow, 5-8h is usually needed, and the investment, the occupied land and the operation cost are high. In addition, the wastewater discharged by the sodium-method flue gas desulfurization device has high salt content, and the discharge of the salt-containing wastewater is forbidden in many places, so that the double targets of realizing zero emission of the desulfurization wastewater and standard discharge of the desulfurization purified flue gas become a problem of special concern.
Chinese patent CN107349785A relates to a multifunctional flue gas treatment system, which comprises an SCR denitration unit, a flue gas-air heat exchange unit, a bag-type dust removal unit, a desulfurization tower, a heating unit and a smoke discharge unit, which are connected in sequence by pipes. And a wet and electric demisting unit is arranged between the desulfurizing tower and the heating unit, and is used for removing fog drops in the flue gas treated by the desulfurizing tower and discharging the treated flue gas into the heating unit, and the flue gas is discharged into the smoke discharging unit after heat exchange with hot air output from the flue gas-air heat exchange unit in the heating unit. The desulfurizing tower is also communicated with a wastewater treatment unit, and the wastewater treatment unit is used for receiving the wastewater discharged by the desulfurizing tower and treating the wastewater. The invention can effectively remove sulfur dioxide and nitrogen oxide in the flue gas, and can also effectively utilize waste heat and treat waste water. But has the defects of long processing flow, complex processing process, high processing energy consumption and the like.
Chinese patent CN105381699A relates to a method and a device for desulfurization and denitrification by combining hydrogen peroxide oxidation and an amino wet method, and firstly, a sulfite solution with reducibility is obtained by efficiently removing sulfur dioxide by using an amino solution. Secondly, nitrogen monoxide in the desulfurization gas is efficiently oxidized by using high-activity free radicals obtained by decomposing hydrogen peroxide on the surface of the catalyst. And finally, mixing and reacting the sulfite solution and the nitrogen oxide, thereby achieving the aim of efficiently absorbing the nitrogen oxide. The invention establishes a desulfurization and denitrification mode for efficiently removing the flue gas product in a liquid phase and recycling the product. But still has the defects of long processing flow, complex processing process, high processing energy consumption and the like.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a method and a device for treating sulfur-containing flue gas. The invention combines olefin waste alkali liquid treatment and microalgae culture to treat SO-containing substances2、CO2、NOXThe flue gas realizes the high-efficiency treatment of the flue gas, does not need to use a catalyst and a large amount of absorbent, and has the advantages of good removal effect, low treatment cost, economy, environmental protection and the like.
The invention provides a method for treating sulfur-containing flue gas, which comprises the following steps:
(1) introducing the flue gas into a desulfurization reactor, and taking olefin waste alkali liquor as an absorbent to obtain desulfurization waste liquid and desulfurization flue gas;
(2) causticizing and regenerating the desulfurization waste liquid to obtain a precipitate, and calcining at high temperature to obtain high-concentration SO2Reacting with the desulfurized flue gas obtained in the step (1) to prepare sulfur;
(3) introducing the gas generated in the step (2) into a photobioreactor for microalgae culture, and collecting exhaust gas, wherein the microalgae is tolerant to NOx;
(4) carrying out solid-liquid separation on the culture system in the step (3), and respectively harvesting microalgae cells and filtrate;
(5) adding sodium peroxide into the filtrate obtained in the step (4), and introducing the exhaust gas obtained in the step (4) into the filtrate for reaction to obtain purified gas;
(6) and (5) performing denitrification treatment on the filtrate after treatment in the step (5).
In the invention, the sulfur-containing flue gas in the step (1) contains NOx and SO2、CO2Of flue gas, NOx being mainly NO and/or NO2For example, the flue gas can be any one or a mixture of a plurality of flue gases from coal-fired flue gas, burning tail gas of a sulfur recovery device, catalytic cracking regeneration tail gas and the like.
In the present invention, the desulfurization reactor in step (1) is a reactor conventionally used in the art, and may be, for example, a desulfurization absorption tower. The olefin waste alkali liquor mainly comprises ethylene waste alkali liquor, propylene waste alkali liquor and the like, wherein a large amount of free alkali, sodium sulfide, sodium carbonate, organic matters and the like are contained, and the olefin waste alkali liquor can be derived from waste alkali liquor generated in the process of preparing propylene by propane dehydrogenation and preparing ethylene by ethane dehydrogenation in the petrochemical industry. In the absorption process, the pH value of the absorption liquid is controlled to be 4.5-7, preferably 5-6.5. The generated desulfurized flue gas mainly contains H2S、CO2NOx, VOCs, and the like, SO2The removal rate is more than 95 percent.
In the invention, lime is used for causticizing regeneration in the step (2), and the lime can be at least one of hydrated lime, quicklime, limestone and the like, and the hydrated lime is preferred. The precipitate obtained is mainly CaSO3Calcining at high temperature to obtain CaO and high-concentration SO2CaO can be recycled to the causticizing regeneration process. High concentration of SO2And H in the desulfurized flue gas of the step (1)2S, reacting to prepare sulfur. The regenerated alkali liquor can be used for sewage regulation of a sewage treatment plant.
In the invention, the microalgae in the step (3) is cultured according to NOx and CO in the flue gas2The content of CO in each stage of photobioreactor can be controlled by arranging a plurality of stages of photobioreactors2The content is less than 45v%, preferably 5v% to 35 v%; NOx content below 0.1v%, preferably below 0.06 v%; the ventilation amount is 0.1 to 1.0 vvm.
In the invention, the microalgae culture medium and the microalgae seed liquid are inoculated into the photobioreactor in the step (3), and the microalgae culture medium adopts a liquid culture medium for culturing microalgae, such as BG11, SE, BBM and the like which are well known in the field. The microalgae culture medium and the microalgae seed liquid are prepared by the conventional method in the field, and the inoculation amount of the microalgae seed liquid is 1-50%, preferably 5-30% of the volume of the culture medium.
In the invention, the microalgae tolerant to NOx in the step (3) is any one of the microalgae capable of tolerating NOx disclosed, preferably, the microalgae is fibrophyta (A)Ankistrodesmus sp.) SS-B7, which is preserved in China general microbiological culture Collection center of China Committee for culture Collection of microorganisms (CGMCC 7478) 4.15.2013 at the preservation address of China academy of sciences microbial research institute No. 3, North Cheng West Lu No. 1 Hospital, Chaoyang, Beijing. This strain has been published in CN 105713836a and submitted for preservation and proof of survival. The volume ratio of the inoculated fibrophyta SS-B7 seed liquid to the microalgae culture medium is 1: 20-1: 5.
Further, a proper amount of chlorella (Chlorella) is added at the same timeChlorella sp.) SF-B1, the genus Chlorella (A)Chlorella sp.) SF-B1 has been deposited in the general microbiological center of China Committee for culture Collection of microorganisms (CGMCC) No. 11005 at 7/6/2015 with the collection address of the institute for microbiology, China academy of sciences No. 3, Siro 1, North Cheng, the sunward area, Beijing. When chlorella SF-B1 is inoculated, the volume ratio of chlorella SS-B7 to chlorella SF-B1 seed liquid is 1:1-50: 1.
In the invention, the preparation method of the seed liquid of the fibroalgae SS-B7 and the chlorella SF-B1 comprises the following steps: adjusting the pH value of a microalgae culture medium to 6-9, carrying out shaking culture at the temperature of 20-30 ℃, the illumination period of 24 hours, the light-dark time ratio of 14: 10-10: 14 and the illumination intensity of 2000-10000 Lux until the microalgae culture medium reaches the logarithmic phase.
In the invention, the microalgae culture conditions in the step (3) are as follows: the temperature is 10-35 ℃, the illumination period is 24 hours, the light-dark time ratio is 10: 14-14: 10, the pH value is 6-9, the illumination intensity is 2000-20000 Lux, and the culture is carried out until the growth stabilization period is finished.
In the invention, the solid-liquid separation in the step (4) adopts the modes of centrifugation, filtration and the like to respectively harvest microalgae cells and filtrate, and the dry weight of the cells and the oil content are measured, wherein the dry weight of the cells can reach more than 10g/L, and the oil content can reach more than 40 percent of the dry weight of the cells.
In the invention, the stepsAnd (5) adding a certain amount of sodium peroxide into the filtrate, specifically determining according to the content of residual NOx in the exhaust gas, and converting the sodium peroxide into nitrite, wherein the preferable adding amount is 1-30 g/L. In the obtained purified gas, CO2The removal rate reaches more than 65 percent, and the NOx removal rate reaches more than 80 percent.
In the invention, the filtrate obtained in the step (5) is mainly nitrite and nitrate, denitrifying bacteria are inoculated for denitrification treatment, and the concentration of the inoculated sludge is 2000-10000 mg/L. The removal rate of the total nitrogen in the effluent reaches over 90 percent.
The invention also provides a treatment device for the flue gas-containing treatment method, which comprises a desulfurization system, a causticization regeneration system, a calcination system, a sulfur recovery system, a photo-biological reaction system, a solid-liquid separation system, an oxidation system and a denitrification system, wherein the desulfurization system mainly comprises a desulfurization absorption tower and is used for removing SO by contacting olefin waste alkali liquor and sulfur-containing flue gas2And obtaining desulfurized waste liquid and desulfurized flue gas; the causticization regeneration system is used for causticization regeneration of the desulfurization waste liquid to obtain CaSO3Precipitate and regenerated alkali liquor; calcination System for converting CaSO3Calcining the precipitate to high concentration SO2And CaO; sulfur recovery system for high concentration SO2Reacting with the desulfurized flue gas to prepare sulfur; the photobioreactor system mainly comprises a plurality of stages of photobioreactors, microalgae culture is carried out by using the introduced sulfur recovery tail gas, and exhaust gas is collected; the solid-liquid separation system is used for carrying out solid-liquid separation on the microalgae culture system, and harvesting microalgae cells to obtain filtrate; the oxidation system is used for adding sodium peroxide into the filtrate and introducing exhaust gas to obtain purified gas; and the denitrification system is used for carrying out denitrification treatment on the filtrate obtained by oxidation.
Compared with the prior art, the invention has the following advantages:
(1) the method couples the olefin waste alkali liquid treatment with the microalgae culture process to treat the SO-containing substances2、CO2、NOXThe flue gas realizes the high-efficiency treatment of the flue gas, does not need to use a catalyst and a large amount of absorbent, and has the advantages of good removal effect, low treatment cost, economy, environmental protection and the like.
(2) The olefin waste alkali liquor is used as a desulphurization absorbent, so that the desulphurization can be carried out efficiently, the useful substances in the waste alkali liquor and the smoke can be recovered and reused, the waste is treated by waste, and the environmental protection benefit and the economic benefit are obviously improved.
(3) By tolerant NOXThe microalgae of (1) can be used for treating flue gas, and CO which is generated by acidification of flue gas and waste alkali liquor and can tolerate high concentration2And generate O2Make NO presentXFormation of NO in water3 -And NO2 -And then converted to N in the course of denitrification2The above processes act synergistically to achieve CO2And NOXThe removal is efficient.
(4) Tolerance to NO with Cellulosia SS-B7XGood performance and high carbon fixation efficiency, and can obtain high-yield algae cells. Adopts chlorella (A) and (B)Chlorella sp.)SF-B1,NOXThe removal effect is better, and the dosage of sodium peroxide is reduced.
(5) The invention can treat SO-containing gas in an environment-friendly and economical way2、NOX、CO2The smoke can also obtain the microalgae cells with high oil content, and the economic benefit and the environmental protection benefit are obviously improved.
Drawings
FIG. 1 is a schematic flow diagram of the flue gas treatment of the present invention;
wherein, 1-desulfurization system, 2-causticization regeneration system, 3-CaSO3A calcination system, a 4-sulfur recovery system, a 5-photo-biological reaction system, a 6-solid-liquid separation system, a 7-oxidation system and a 8-denitrification system;
101-flue gas, 102-desulfurized flue gas, 103-sulfur recovery tail gas, 104-exhaust gas, 105-purified gas and 106-nitrogen gas; 201-olefin waste alkali liquor, 202-desulfurization waste liquid, 203-regenerated alkali liquor; 301-lime, 302-CaSO3Precipitate, 303-quicklime; 401-SO2402-sulphur; 501-microalgae cells, 502-filtrate; 601-sodium peroxide.
Detailed Description
The present invention will be described in further detail by way of examples. The embodiments are implemented on the premise of the technical scheme of the invention, and detailed implementation modes and specific operation processes are given, but the protection scope of the invention is not limited by the following embodiments. In the present invention, v% is a volume fraction.
The experimental procedures in the following examples are, unless otherwise specified, conventional in the art. The experimental materials used in the following examples were purchased from a conventional biochemical reagent store unless otherwise specified.
The flue gas treatment device of the invention is shown in figure 1 and comprises a desulfurization system 1, a causticization regeneration system 2 and CaSO3A calcining system 3, a sulfur recovery system 4, a photo-biological reaction system 5, a solid-liquid separation system 6, an oxidation system 7 and a denitrification system 8, wherein the desulfurization system 1 mainly comprises a desulfurization absorption tower, and flue gas 101 is introduced into the tower to contact with olefin waste lye 201 to remove SO2And obtaining desulfurized flue gas 102 and desulfurized waste liquid 202; lime 301 is added into the causticization regeneration system 2 to causticize and regenerate the desulfurization waste liquid 202 to obtain CaSO3Precipitate 302 and regeneration lye 203; mixing CaSO3The precipitate is calcined in a calcination system 3 to a high concentration of SO2 401 and quicklime 303; high concentration of SO2Reacting with the desulfurized flue gas in a sulfur recovery system 4 to prepare sulfur 402; the sulfur recovery tail gas 103 generated by the sulfur recovery system enters the photo-biological reaction system 5 for microalgae culture, and the exhaust gas 104 is collected; separating the microalgae culture system in a solid-liquid separation system 6 to obtain microalgae cells 501 and a filtrate 502; adding sodium peroxide 601 into the filtrate 501 in the oxidation system 7, and introducing exhaust gas 104 for reaction to obtain purified gas 105; the filtrate obtained by oxidation is subjected to denitrification treatment in a denitrification system 8.
The removal rate of the invention is (gas content-vent gas content)/gas content.
The culture of the microalgae adopts BG11 culture medium, and the formula is shown in tables 1 and 2.
TABLE 1 BG11 culture Medium
Figure DEST_PATH_IMAGE002
Table 2 composition of a5+ Co solution in table 1
Figure DEST_PATH_IMAGE004
Preparing BG11 liquid culture medium according to tables 1 and 2, adjusting pH to 8.0, inoculating fibroalgae SS-B7 and chlorella SF-B1 into microalgae culture medium, culturing in a constant temperature light shaking table at 25 deg.C with light period of 24h, light-dark time ratio of 14:10 and light intensity of 5000Lux at 120rpm, and performing shaking culture to logarithmic phase to obtain fibroalgae SS-B7 and chlorella SF-B1 seed solution.
The denitrification sludge used in the embodiment of the invention is taken from a denitrification treatment tank of a certain sewage treatment plant, and the removal rate of the total nitrogen in the effluent reaches more than 90 percent. The total nitrogen concentration of the effluent is detected by GB 11894-89 'determination of water quality-total nitrogen-alkaline potassium persulfate digestion ultraviolet spectrophotometry'.
The flue gas adopted by the invention contains NOx and SO2、CO2Of flue gas, NOx being mainly NO and/or NO2. The content of pollutants in the flue gas is detected by a flue gas analyzer.
Example 1
Waste lye produced by an ethylene plant of a certain enterprise, wherein the COD is 58000mg/L and the sodium sulfide concentration is 2.9wt% (S)2-: 12200 mg/L), a sodium carbonate concentration of 2.0wt% (20500 mg/L), and a sodium hydroxide concentration of 1.6 wt%.
The smoke generated by a certain enterprise mainly comprises the following components: CO 2214% by volume, and 0.06% by volume of NOx (wherein NO accounts for 90%), SO2The content was 0.04 v%.
Introducing the flue gas into a desulfurization absorption tower, taking ethylene waste alkali liquor as an absorbent, circularly absorbing in the desulfurization tower, controlling the pH of absorption liquid to be 5-6, discharging part of desulfurization absorption liquid when the pH is lower than 5, starting to supplement the waste alkali liquor, and stopping supplementing when the pH reaches 6 to obtain the desulfurization flue gas. The discharged desulfurization absorption liquid mainly contains sodium bisulfite, slaked lime is added to causticize and regenerate the desulfurization waste liquid to obtain CaSO3Calcining the precipitate at high temperature to obtain high-concentration SO2And quicklime, which is recycled to the causticizing regeneration process. High concentration of SO2And (2) desulfurizing the flue gasMiddle H2S reaction of SO2And H2The molar ratio of S is 1:2, and SO is added under the action of aluminum-based catalyst2And H2S reaction to obtain sulfur. In the tail gas obtained from the sulfur recovery system, CO2The content was 16v%, and the NOx content was about 0.05 v%.
And introducing the sulfur recovery tail gas into a photobioreactor for microalgae culture, wherein the ventilation volume is 0.5 vvm. Adding 6L of microalgae culture medium and 1.0L of prepared fibroalgae SS-B7 seed solution into a photobioreactor, culturing at 25 deg.C and illumination period of 5000Lux for 24 hr, and adjusting light-dark time ratio to 14: 10. In the collected exhaust gas, CO2The removal rate was 70%, and the NOx removal rate was 36%.
After 8 days of culture, microalgae cells and filtrate were harvested by centrifugation. And (4) measuring the dry weight and the oil content of the cells. And (3) carrying out vacuum freeze drying at the temperature of-60 ℃ to constant weight, measuring the dry weight of the algae powder, calculating the biomass yield, and measuring the total lipid content by adopting a normal hexane-ethyl acetate method. After detection, the dry cell weight can reach 11.2g/L, and the oil content is 41.7% of the dry cell weight.
And adding sodium peroxide into the filtrate with the addition of 6.5g/L, and introducing the collected exhaust gas into the filtrate for treatment to obtain purified gas. Purifying the gas of CO2The removal rate was 75%, and the NOx removal rate was 80%. The filtrate after reaction is connected with the denitrification sludge, the sludge concentration is 5000mg/L, and the total nitrogen removal rate in the effluent reaches more than 90 percent.
Example 2
Waste lye produced by an ethylene plant of an enterprise, wherein the COD is 33000mg/L and the sodium sulfide concentration is 2.1wt% (S)2-: 8831 mg/L), a sodium carbonate concentration of 1.1wt% (11275 mg/L), and a sodium hydroxide concentration of 1.2 wt%.
The smoke generated by a certain enterprise mainly comprises the following components: CO 2210% by volume, 0.04% by volume NOx, SO2The content was 0.03 v%.
Introducing the flue gas into a desulfurization absorption tower, taking ethylene waste alkali liquor as an absorbent, circularly absorbing in the desulfurization tower, controlling the pH of absorption liquid to be 5.5-6.5, discharging part of desulfurization absorption liquid when the pH is lower than 5.5, starting to supplement the ethylene waste alkali liquor, and when the pH reaches to the value of 5.5And when 6.5 hours, stopping replenishing to obtain the desulfurized flue gas. The discharged desulfurization absorption liquid mainly contains sodium bisulfite, slaked lime is added to causticize and regenerate the desulfurization waste liquid to obtain CaSO3Calcining the precipitate at high temperature to obtain high-concentration SO2And quicklime, which is recycled to the causticizing regeneration process. High concentration of SO2And step (1) desulfurizing H in flue gas2S reaction of SO2And H2The molar ratio of S is 1:2, and SO is added under the action of aluminum-based catalyst2And H2S reaction to obtain sulfur. In the tail gas obtained from the sulfur recovery system, CO2The content was 11v%, and the NOx content was 0.03 v%.
And introducing the sulfur recovery tail gas into a photobioreactor for microalgae culture, wherein the ventilation volume is 0.5 vvm. Adding 6L of microalgae culture medium and 0.9L of prepared fibroalgae SS-B7 seed solution into a photobioreactor, culturing at 25 deg.C and illumination period of 5000Lux for 24 hr, and adjusting light-dark time ratio to 14: 10. In the collected exhaust gas, CO2The removal rate was 75%, and the NOx removal rate was 40%.
After 7 days of culture, microalgae cells and filtrate were harvested by centrifugation. And (4) measuring the dry weight and the oil content of the cells. And (3) carrying out vacuum freeze drying at the temperature of-60 ℃ to constant weight, measuring the dry weight of the algae powder, calculating the biomass yield, and measuring the total lipid content by adopting a normal hexane-ethyl acetate method. After detection, the dry cell weight can reach 11.3g/L, and the oil content is 43.1 percent of the dry cell weight.
And adding sodium peroxide into the filtrate in an amount of 3.2g/L, and introducing the collected exhaust gas into the filtrate for treatment to obtain purified gas. Purifying the gas of CO2The removal rate was 80%, and the NOx removal rate was 85%. The filtrate after reaction is connected with the denitrification sludge, the sludge concentration is 5000mg/L, and the total nitrogen removal rate in the effluent reaches more than 90 percent.
Example 3
The waste alkali liquor produced in the olefin production by propane dehydrogenation of a certain enterprise contains 6.83wt% of sodium sulfide, 4.85wt% of sodium hydrosulfide, 117300mg/L of COD and has a pH value of 13.5.
The smoke generated by a certain enterprise mainly comprises the following components: CO 2220% by volume, 0.05% by volume NOx, SO2The content was 0.02 v%.
Introducing the flue gas into a desulfurization absorption tower, taking propylene waste alkali liquor as an absorbent, circularly absorbing in the desulfurization tower, controlling the pH of absorption liquid to be 5-6, discharging part of desulfurization absorption liquid when the pH is lower than 5, starting to supplement the propylene waste alkali liquor, and stopping supplementing when the pH reaches 6 to obtain the desulfurization flue gas. The discharged desulfurization absorption liquid mainly contains sodium bisulfite, slaked lime is added to causticize and regenerate the desulfurization waste liquid to obtain CaSO3Calcining the precipitate at high temperature to obtain high-concentration SO2And quicklime, which is recycled to the causticizing regeneration process. High concentration of SO2And step (1) desulfurizing H in flue gas2S reaction of SO2And H2The molar ratio of S is 1:2, and SO is added under the action of aluminum-based catalyst2And H2S reaction to obtain sulfur. In the tail gas obtained from the sulfur recovery system, CO2The content was 22v%, and the NOx content was 0.04 v%.
And introducing the sulfur recovery tail gas into a photobioreactor for microalgae culture, wherein the ventilation volume is 0.3 vvm. Adding 6L of microalgae culture medium and 1.2L of prepared fibroalgae SS-B7 seed solution into a photobioreactor, culturing at 25 deg.C and illumination intensity of 5000Lux for 24 hr, and adjusting light-dark time ratio to 14: 10. In the collected exhaust gas, CO2The removal rate was 63% and the NOx removal rate was 39%.
After 8 days of culture, microalgae cells and filtrate were harvested by centrifugation. And (4) measuring the dry weight and the oil content of the cells. And (3) carrying out vacuum freeze drying at the temperature of-60 ℃ to constant weight, measuring the dry weight of the algae powder, calculating the biomass yield, and measuring the total lipid content by adopting a normal hexane-ethyl acetate method. After detection, the dry cell weight can reach 10.5g/L, and the oil content is 41.4% of the dry cell weight.
And adding sodium peroxide into the filtrate in an amount of 3.1g/L, and introducing the collected exhaust gas into the filtrate for treatment to obtain purified gas. Purifying the gas of CO2The removal rate was 68% and the NOx removal rate was 80%. The filtrate after reaction is connected with the denitrification sludge, the sludge concentration is 5000mg/L, and the total nitrogen removal rate in the effluent reaches more than 90 percent.
Example 4
By mixing with fruitThe same culture procedure and culture conditions as in example 1 were used, except that: chlorella SF-B1 is added while culturing microalgae, the inoculation amount is unchanged, and the volume ratio of the Chlorella SF-B1 seed liquid to the Chlorella SS-B7 seed liquid is 1: 1. CO in the collected exhaust gas2The removal rate was 75%, and the NOx removal rate was 70%. The addition amount of sodium peroxide is reduced by nearly half, and CO in the obtained purified gas2The removal rate was 85% and the NOx removal rate was 90%. The total nitrogen removal rate in the treated effluent reaches over 90 percent.
Example 5
The same culture procedure and culture conditions as in example 1 were used, except that: chlorella SF-B1 is added while culturing microalgae, the inoculation amount is unchanged, and the volume ratio of the Chlorella SF-B1 seed liquid to the Chlorella SS-B7 seed liquid is 1: 5. CO in the collected exhaust gas2The removal rate was 75%, and the NOx removal rate was 60%. The addition amount of sodium peroxide is reduced by about one third, and CO in the obtained purified gas2The removal rate was 82% and the NO removal rate was 86%. The total nitrogen removal rate in the treated effluent reaches over 90 percent.
Comparative example 1
The same culture procedure and culture conditions as in example 1 were used, except that: controlling the pH value of the absorption liquid to be 3-4. Because the pH value is too low, the normal operation of a sulfur recovery system is influenced, and excessive SO exists in the sulfur recovery tail gas2Or H2And S, further influencing the normal operation of microalgae culture.
Comparative example 2
The same culture procedure and culture conditions as in example 1 were used, except that: no sodium peroxide was added. The removal rate of NOx in the purified gas was about 40%.
Comparative example 3
The same culture procedure and culture conditions as in example 1 were used, except that: the Chlorella vulgaris FY1# described in CN102311921A is used, because NO is not tolerantXTherefore, after a period of growth, a large number of the plants die, and subsequent processes cannot be performed.
In summary, the method couples the olefin waste lye treatment with the microalgae culture process to treat the SO-containing wastewater2、CO2、NOXThe smoke and the solids ofThe method has the advantages of high-efficiency treatment of the flue gas, no need of using a catalyst and a large amount of absorbent, good removal effect, low treatment cost, economy, environmental protection and the like. The olefin waste alkali liquor is used as a desulphurization absorbent, so that the desulphurization can be carried out efficiently, and useful substances in the waste alkali liquor and the smoke can be recovered and reused to treat wastes with processes of wastes against one another. Meanwhile, the microalgae grease can be obtained, and the economic benefit and the environmental benefit are obviously improved.

Claims (16)

1. The method for treating the sulfur-containing flue gas is characterized by comprising the following steps of:
(1) introducing the flue gas into a desulfurization reactor, and taking olefin waste alkali liquor as an absorbent to obtain desulfurized flue gas and desulfurized waste liquor; the olefin waste alkali liquor is mainly ethylene waste alkali liquor or propylene waste alkali liquor, and contains free alkali, sodium sulfide, sodium carbonate and organic matters;
(2) causticizing and regenerating the desulfurization waste liquid to obtain a precipitate, and calcining at high temperature to obtain high-concentration SO2Reacting with the desulfurized flue gas obtained in the step (1) to prepare sulfur;
(3) introducing the gas generated in the step (2) into a photobioreactor for microalgae culture, and collecting exhaust gas, wherein the microalgae is fibroalgae SS-B7 with the preservation number of CGMCC number 7478; inoculating fibrochlorella SS-B7, and adding chlorella SF-B1 with preservation number of CGMCC number 11005;
(4) carrying out solid-liquid separation on the culture system in the step (3), and respectively harvesting microalgae cells and filtrate;
(5) adding sodium peroxide into the filtrate obtained in the step (4), and introducing the exhaust gas obtained in the step (4) into the filtrate for reaction to obtain purified gas;
(6) and (5) performing denitrification treatment on the filtrate after treatment in the step (5).
2. The method of claim 1, wherein: the sulfur-containing flue gas in the step (1) contains NOx and SO2And CO2Of flue gas, NOx being mainly NO and/or NO2The catalyst is derived from any one or a mixture of a coal-fired flue gas, a sulfur recovery device incineration tail gas and a catalytic cracking regeneration tail gas.
3. The method of claim 1, wherein: and (1) controlling the pH value of the absorption liquid to be 4.5-7.
4. The method of claim 3, wherein: and (1) controlling the pH value of the absorption liquid to be 5-6.5.
5. The method of claim 1, wherein: lime is used for causticizing regeneration in the step (2), and the obtained precipitate is mainly CaSO3Calcining at high temperature to obtain CaO and high-concentration SO2And recycling CaO to the causticization regeneration process.
6. The method of claim 1, wherein: and (3) causticizing regeneration in the step (2) adopts at least one of slaked lime, quicklime and limestone.
7. The method of claim 1, wherein: step (3) culturing microalgae according to NOx and CO in flue gas2Content, setting multiple stages of photobioreactor, controlling CO in each stage of photobioreactor2The content is less than 45v%, the NOx content is less than 0.1v%, and the ventilation volume is 0.1-1.0 vvm.
8. The method of claim 7, wherein: controlling CO in each stage of photobioreactor2The content is 5-35 v%, and the NOx content is lower than 0.06 v%.
9. The method of claim 1, wherein: the microalgae culture medium in the step (3) adopts BG11, SE and BBM liquid culture medium for culturing microalgae; the inoculation amount of the microalgae seed liquid is 1-50% of the volume of the culture medium.
10. The method of claim 9, wherein: the inoculation amount of the microalgae seed liquid is 5-30% of the volume of the culture medium.
11. The method of claim 1, wherein: the inoculation volume ratio of the fibroalgae SS-B7 to the chlorella SF-B1 is 1:1-50: 1.
12. The method according to claim 1 or 11, characterized in that: the preparation method of the seed liquid of the fibrophyta SS-B7 and the chlorella SF-B1 comprises the following steps: adjusting the pH value of a microalgae culture medium to 6-9, carrying out shaking culture at the temperature of 20-30 ℃, the illumination period of 24 hours, the light-dark time ratio of 14: 10-10: 14 and the illumination intensity of 2000-10000 Lux until the microalgae culture medium reaches the logarithmic phase.
13. The method of claim 1, wherein: the microalgae culture conditions in the step (3) are as follows: the temperature is 10-35 ℃, the illumination period is 24 hours, the light-dark time ratio is 10: 14-14: 10, the pH value is 6-9, the illumination intensity is 2000-20000 Lux, and the culture is carried out until the growth stabilization period is finished.
14. The method of claim 1, wherein: the adding amount of the sodium peroxide in the step (5) is 1-30 g/L.
15. The method of claim 1, wherein: and (5) inoculating the filtrate obtained in the step (5) into denitrifying bacteria for denitrification treatment, wherein the concentration of the inoculated sludge is 2000-10000 mg/L.
16. A flue gas treatment plant for use in the method of any one of claims 1 to 15, comprising a desulfurization system, a causticization regeneration system, a calcination system, a sulfur recovery system, a photo-biological reaction system, a solid-liquid separation system, an oxidation system and a denitrification system.
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