CN214360799U - Desulfurization waste lye zero discharge combined treatment process unit - Google Patents
Desulfurization waste lye zero discharge combined treatment process unit Download PDFInfo
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Abstract
The utility model discloses a zero-discharge combined treatment process device for desulfurization waste lye; the device is mainly formed by sequentially connecting a pretreatment system, a concentration system, an incineration system and a crystallization system; the pretreatment system is provided with a reaction device and a separation unit, the separation unit mainly comprises a solid settling unit and/or a filtering unit, and the waste alkali liquor and the desulfurization wastewater are reacted by the reaction device and then separated into supernatant and solid precipitate by the separation unit; the concentration system is used for concentrating the supernatant to obtain a concentrated solution; the incineration system mainly comprises an incinerator, a quenching device, a waste heat recovery device and a post-treatment device, wherein the incinerator, the quenching device, the waste heat recovery device and the post-treatment device are sequentially connected; the incinerator is also connected with a crystallization system through a quenching device; the crystallization system is used for evaporating and crystallizing the salt solution from the quenching device to obtain crystallized salt and discharging the crystallized salt; the crystallization system is also connected with a waste heat recovery device through a pipeline.
Description
Technical Field
The utility model relates to a desulfurization waste water and waste lye zero release combined treatment process units belongs to waste water, organic waste liquid zero release environmental protection technical field.
Background
The power supply structure of China is mainly based on thermal power, a large amount of burning of fossil fuels such as coal of a thermal power plant causes serious environmental problems, and the emission of sulfur dioxide can not only directly cause harm to the ecological environment, but also is an important precursor formed by acid rain, dust haze and the like. At present, limestone-gypsum wet desulfurization process is mostly used for flue gas desulfurization of thermal power plants, but desulfurization waste water generated by the wet desulfurization process contains a large amount of suspended matters, inorganic salts, gypsum particles, fluorides, heavy metals and the like (typical water quality is shown in table 1), and the desulfurization waste water must be recycled or treated under the environment-friendly high-pressure situation. The zero-emission treatment of the desulfurization wastewater is also a hot spot of wastewater treatment research and application in recent years. The conventional zero-discharge process of the desulfurization wastewater at present comprises three sections of pretreatment, membrane concentration and evaporative crystallization. The pretreatment comprises adding drugs to adjust pH, removing calcium and magnesium hardness ions, fluoride ions and heavy metal ions, and removing suspended particles; the membrane concentration comprises the steps of concentrating the wastewater by utilizing membrane technologies such as ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, electrodialysis and the like, so that the wastewater treatment capacity of an evaporation crystallization section is reduced, and the equipment investment and the operation energy consumption are reduced; the evaporative crystallization comprises the step of further concentrating the wastewater by utilizing technologies such as multi-effect evaporative crystallization, MVR evaporative crystallization and the like until crystal salt is separated out. More than 95% of water resources can be recycled in the membrane concentration section and the evaporation crystallization section, and the crystallized salt can be used as a snow-melting agent, so that zero discharge of desulfurization wastewater is realized.
TABLE 1 typical Water quality composition of desulfurized waste Water
In the petrochemical production process, NaOH solution is often used to absorb hydrogen sulfide, alkaline-washed oil products and cracked gas, and waste alkali liquor containing a large amount of pollutants, typically ethylene waste alkali liquor and oil refining waste alkali liquor, is generated. The COD content of the wastewater is high and can reach tens of thousands mg/L, and the wastewater is difficult to biodegrade. Contains inorganic and organic sulfides such as sulfide and mercaptan, and makes the waste liquid have strong and unpleasant odor. The waste liquid contains a large amount of inorganic substances such as sodium carbonate, sodium hydroxide, sodium sulfide and the like, and organic substances such as petroleum, sodium phenolate, sodium naphthenate and the like, and has high alkalinity and pH value of more than 12 (the typical water quality is shown in Table 2). Although the yield of the waste lye is gradually reduced by the technical improvement of oil refining and chemical enterprises, the treatment difficulty is increasingly greater. At present, the conventional treatment mode of the waste alkali liquor is to discharge the waste alkali liquor after the sulfide is removed by a wet oxidation method to reduce COD (chemical oxygen demand), and then the waste alkali liquor is subjected to biochemical sewage treatment and reaches the standard, but the removal efficiency of the waste alkali liquor subjected to wet oxidation treatment to the COD is still very limited, and the high-COD saline water causes serious impact and damage to a sewage biochemical system, so that the normal operation of a sewage treatment plant and the discharge of the total wastewater reaching the standard are influenced. In addition, the high heat value of the water content of the waste alkali liquor is low, so that the incineration method is high in treatment cost and is generally not recommended. However, by high temperature incineration, sulfides can be oxidized to sulfur dioxide, and organic matter can be oxidized to CO2And H2O, high burning-out rate of organic matters and good removing effect. The waste alkali liquor is treated by adopting an incineration method, the operation is simple, and the emission requirement reaching the standard can be met.
TABLE 2 typical Water quality composition of ethylene spent lye
| Index (I) | Unit of | Numerical value |
| pH | 12-14 | |
| NaOH | ％ | 1-3 |
| Na2S | ％ | 1-4 |
| Na2CO3 | ％ | 6-10 |
| NaRS | ％ | 0-0.2 |
| Cyanide compounds | ％ | 0-0.05 |
| Dissolved hydrocarbons | ％ | 0.1-0.3 |
| COD | mg/L | 10000-50000 |
| Oil | mg/L | ＞500 |
Considering that oil refining and chemical industries are energy-consuming households and mostly own self-contained power plants, a part of desulfurization wastewater can be generated by adopting a wet-type flue gas desulfurization process treatment according to the national flue gas purification treatment policy of the power plants. The waste alkali liquor is a kind of waste water produced by oil refining and chemical industry. With the stricter environmental protection policy, the desulfurization wastewater and the waste alkali liquor are treated and discharged after reaching standards. If the two waste waters are treated separately, the investment in equipment and the operating cost are both high. The two-step wastewater discharge and water quality characteristics are combined, the combined treatment has obvious economical efficiency and advantages, and the equipment investment and the operation and maintenance cost are greatly reduced. In combination with the analysis of the advantages and the disadvantages of the existing desulfurization wastewater and waste alkali liquor treatment process, the problem to be mainly solved by the combined treatment process is that heavy metal ions and hardness ions in the desulfurization wastewater are removed; removing sulfides and organic matters in the waste alkali liquor; the energy consumption of the process is reduced and optimized; and (4) effectively recycling resources.
SUMMERY OF THE UTILITY MODEL
Aiming at the defects of the prior art, the utility model aims at providing a zero discharge combined treatment process device for desulfurization wastewater and waste lye. The utility model relates to a desulfurization waste water is the waste water that adopts wet-type desulfurization process to produce to the flue gas, especially the waste water that the lime stone-gypsum flue gas desulfurization process that the power plant generally used produced. The waste alkali liquor refers to waste water containing a large amount of pollutants generated by absorbing hydrogen sulfide, alkaline-washed oil products and cracked gas by sodium hydroxide alkali liquor in the production process of the oil refining industry and the chemical industry, in particular to waste alkali liquor of an ethylene device. The desulfurization wastewater treatment focuses on the removal of heavy metal ions and calcium-magnesium hardness ions, and the waste alkali liquor treatment focuses on the removal of sulfides and organic matters. Desulfurization waste water and waste lye all belong to the high waste water that contains salt, and this practical combined treatment process units finally realizes that the zero liquid of two strands of waste water is outer to be arranged, and waste gas discharge to reach standard, and water and salt are retrieved and are recycled.
The utility model provides a technical scheme that its technical problem adopted is:
a zero-discharge combined treatment process device for desulfurization wastewater and waste lye mainly comprises a pretreatment system, a concentration system, an incineration system and a crystallization system; the pretreatment system, the concentration system, the incineration system and the crystallization system are connected in sequence;
the pretreatment system is provided with a reaction device and a separation unit, the separation unit mainly comprises a solid settling unit and/or a filtering unit, and the waste alkali liquor and the desulfurization wastewater are reacted by the reaction device and then separated into supernatant and solid precipitate by the separation unit;
the concentration system is used for concentrating the supernatant to obtain a concentrated solution;
the incineration system mainly comprises an incinerator, a quenching device, a waste heat recovery device and a post-treatment device, wherein the incinerator, the quenching device, the waste heat recovery device and the post-treatment device are sequentially connected; the incinerator is also connected with a crystallization system through a quenching device;
the crystallization system is used for evaporating and crystallizing the salt solution from the quenching device to obtain crystallized salt and discharging the crystallized salt; the crystallization system is also connected with a waste heat recovery device through a pipeline.
Desulfurization waste water mainly produces in the lime stone-gypsum wet flue gas desulfurization technology of power plant's commonly used, waste water becomes acid, pH is between 4-6, and suspended solid content is at 5000mg/L ~ 20000mg/L, and the salt content is at 2% -6%, contains a large amount of calcium magnesium ion, and hardness is at 5000mg/L-10000mg/L, and anion mainly contains chloride ion and sulfate radical ion, contains the more heavy metal ion of kind in addition, like arsenic, mercury, lead, nickel, zinc etc.. The waste alkali liquor is generated in oil refining and petrochemical industries, such as ethylene waste alkali liquor, the waste water of the waste alkali liquor is alkaline, the pH value is 12-14, the water content is 60-90%, the salt content is 8-12%, the waste alkali liquor is mainly sodium carbonate, wherein the mass ratio of sodium hydroxide is 1-3%, the mass ratio of sulfide is 0.5-2.5%, the content of sodium hydroxide is more than 500mg/L, the COD is 10000mg/L-50000mg/L, and the BOD/COD is less than 0.3, and in addition, the waste alkali liquor also contains organic matters such as hydrocarbons, organic acids and the like.
As the preferred technical scheme of this application, pipeline connection buffer tank and oil-separating jar before the reaction unit, waste lye gets into the oil-separating jar again and gets rid of the butter after the buffer tank homogeneity, then gets into reaction unit and desulfurization waste water reaction, realizes the desorption of acid-base neutralization, sulfur ion, hardness ion and heavy metal ion.
As the preferable technical scheme of the application, the solid settling unit is a settling tank, the wastewater treated by the reaction device is introduced into the settling tank, and a flocculent precipitate is formed after a coagulant and a flocculating agent are added; the rear part of the sedimentation tank is connected with a concentration tank and a medium filter in parallel, and the rear part of the concentration tank is connected with a filter press; the floc precipitate is further concentrated by a concentration tank and then discharged by a filter press; and the clear liquid at the upper part of the sedimentation tank enters a medium filter for filtration and then enters a concentration system for treatment.
Preferably, the sedimentation tank is a high-efficiency sedimentation tank, and is integrated by a coagulation tank, a flocculation tank, a sedimentation tank and sludge concentration, so that the structure is compact.
Preferably, the reaction device is a reaction tank.
More preferably, the pretreatment system comprises a buffer tank, an oil separation tank, a reaction tank, a high-efficiency sedimentation tank, a sludge concentration tank and a filter press which are sequentially connected through a pipeline; the high-efficiency sedimentation tank is also connected with a medium filter pipeline. The method comprises the steps of homogenizing waste alkali liquor in a buffer tank, then feeding the waste alkali liquor into an oil separation tank, removing and recovering butter, mixing the waste alkali liquor with desulfurization wastewater in a reaction tank, combining sulfide and sodium carbonate in the waste alkali liquor with heavy metal ions, calcium ions, magnesium ions and other hardness ions in the desulfurization wastewater to produce precipitates, mixing the waste alkali liquor with the desulfurization wastewater to perform acid-base neutralization reaction, then adding a coagulant and a flocculant into the system, rapidly forming flocculent precipitates by suspended particles, reaction precipitates and colloids in the wastewater under the action of stirring, forming sludge concentrated solution under the action of a high-efficiency sedimentation tank and a sludge concentration tank, dehydrating by a filter press to obtain sludge cakes, transporting the sludge cakes outwards, removing suspended matters from supernatant in the high-efficiency sedimentation tank by a medium filter, and feeding the supernatant into a concentration system.
After the waste alkali liquor is treated by an oil separation tank, the oil content is reduced from more than 500mg/L to less than 5 mg/L; after the desulfurization wastewater is mixed and reacted with the waste alkali liquor, the pH value of effluent is 8-10, heavy metal ions are basically removed, the calcium and magnesium hardness content is not more than 5mg/L, and the removal rate of COD reaches 20-40%; the content of suspended matters in the effluent of the medium filter is not more than 5 mg/L; the water content of the mud cake after compression treatment by the filter press is less than 20 percent, and the mud cake is used as solid waste for outward transportation.
As a preferred technical scheme of the application, the post-treatment device mainly comprises a dust remover, an alkaline washing tower and a chimney, and the dust remover, the alkaline washing tower and the chimney are connected in sequence.
As a preferred technical solution of the present application, the concentration system is an evaporator system, preferably, the evaporator system is a low-temperature evaporator system; more preferably, the cryogenic evaporator system is selected from any one of a multi-effect evaporator, a MVR evaporator, a gas-liquid direct contact evaporator. The cryogenic evaporators of the present application are generally used at temperatures not exceeding 85 ℃. The salt content of the inlet wastewater of the concentration system is 3-10%, the salt content of the outlet wastewater is 20-25%, sodium carbonate and sodium chloride are taken as main materials, and the total ratio is more than 85%.
As the preferable technical scheme of the application, the evaporator system is provided with a secondary steam outlet, and a demister is arranged on the secondary steam outlet to prevent entrainment. And (4) condensing the secondary steam to obtain recovered water with the COD content not more than 200mg/L, and further treating the recovered water by a sewage treatment unit to reach the standard and then discharging.
As the preferred technical scheme of this application, be equipped with atomizing device in the burning furnace, the high concentration that comes out through the concentration system contains salt organic waste water and spouts into the burning furnace through atomizing device.
Preferably, the atomization devices are symmetrically distributed in the incinerator, and low-pressure air, steam or machinery is adopted to atomize the waste liquid.
As a preferred technical scheme of the application, the quenching device is a quenching tank.
As the preferable technical scheme of the application, the waste heat recovery device is a waste heat boiler.
As a preferred technical scheme of the application, the incinerator is externally connected with an auxiliary fuel pipeline and a combustion air pipeline.
As a preferable technical scheme of the application, a waste water outlet pipeline of the alkaline washing tower is connected with a reaction device of a pretreatment system.
The high-concentration salt-containing organic waste liquid is input into an incinerator through an atomization device, and auxiliary fuel and combustion-supporting air are simultaneously input into the incinerator; the waste liquid atomization devices are symmetrically distributed in the incinerator, high-temperature oxidation reaction is carried out in the incinerator, and organic matters in the waste liquid can be oxidized, decomposed and removed; the flue gas outlet of the incinerator is introduced into a quenching tank through a pipeline, high-temperature flue gas is in direct contact heat exchange with spray water and water in the quenching tank in sequence, the temperature is reduced to be below the melting point of inorganic salt, and the inorganic salt enters the quenching tank to form a salt solution with the water; after being quenched and cooled, the flue gas enters a waste heat boiler, and the produced steam is used as a heat supply source; the temperature of the flue gas at the outlet of the waste heat boiler is further reduced, the flue gas enters a dust remover to remove inorganic salt particles and ash content carried in the flue gas, sulfur dioxide, residual ash content and inorganic salt particles in the flue gas are removed through an alkaline washing tower, and finally the flue gas is discharged through a chimney after reaching the standard; and introducing the wastewater discharged by the alkaline tower into a reaction tank of the pretreatment system through a pipeline.
Wherein, the incinerator adopts vertical top burning side feeding, low pressure air, steam or machinery is adopted to atomize the waste liquid, the burning temperature is controlled at 1000-1100 ℃, and the retention time is not less than 2 s. The lining of the incinerator is provided with a wear-resistant and fire-resistant layer and a heat-insulating and fire-resistant heat-insulating layer, so that the falling of the fire-resistant lining caused by molten salt corrosion is prevented. After the high-temperature flue gas is sprayed with water and quenched, the temperature of the high-temperature flue gas is reduced to be below 750 ℃, and the temperature of the flue gas at the outlet of the waste heat boiler is below 200 ℃. The waste heat boiler is preferably a single-drum natural circulating water pipe boiler, and dust in the flue gas is deposited and discharged from an ash bucket at the lower part of the boiler. The dust collector can be a cloth bag type, an electrostatic type or a Venturi type, and the Venturi type is preferred. And a demister is arranged at the outlet of the alkaline washing tower, and water carried in the flue gas is further separated and then discharged into the atmosphere through a chimney.
As the preferred technical scheme of this application, the crystallization system is equipped with the recovery water pipeline, and the recovery water pipeline inserts the quench tank, and the recovery water that obtains after the secondary steam condensation that the crystallization system produced recycles as the spray water of flue gas quench technology. The heating source for the crystallization system is steam generated by the waste heat boiler, and secondary steam generated by the crystallization system is condensed to obtain recovered water which is used as spray water for a flue gas quenching process for recycling. The crystallization system can adopt multiple-effect evaporation crystallization and MVR evaporation crystallization forms to obtain crystallized miscellaneous salt for recycling, or further adopts a quality-divided crystallization process to respectively recover sodium chloride salt and sodium carbonate salt, thereby realizing resource recycling of the salt.
A zero-discharge combined treatment method for desulfurization waste water and waste alkali liquor comprises the steps of mixing and reacting the waste alkali liquor and the desulfurization waste water, precipitating, filtering and removing impurities, further concentrating salt-containing organic waste water by utilizing low-temperature evaporation to approach a salt precipitation point by utilizing clear liquid after the impurities are removed, and then entering an incineration system; high-temperature oxidation reaction is carried out on the high-concentration salt-containing organic waste liquid in an incinerator, and organic matter components are decomposed and removed completely; the generated high-temperature flue gas is discharged from a chimney after being subjected to rapid cooling treatment, waste heat recovery, dust removal and alkali washing treatment in sequence to reach the standard; and (4) enabling the salt solution generated after quenching treatment to enter a crystallization system for treatment to obtain crystallized salt for recovery. The utility model discloses a jointly handle desulfurization waste water and waste lye, finally realize the zero release of desulfurization waste water and waste lye and deal with.
According to the preferable technical scheme, the waste alkali liquor is firstly subjected to buffer homogenization to remove butter and then is mixed with the desulfurization wastewater, sulfides and sodium carbonate in the waste alkali liquor are combined with heavy metal ions, calcium ions, magnesium ions and other hardness ions in the desulfurization wastewater to generate precipitates, and the waste alkali liquor and the desulfurization wastewater are mixed to perform acid-base neutralization reaction; adding coagulant and flocculant into the system, and quickly forming flocculent precipitate from suspended particles, reaction precipitate and colloid in the wastewater; concentrating the flocculent precipitate to form a sludge concentrated solution, and performing filter pressing dehydration to obtain a mud cake for outward transportation; the supernatant is filtered to further remove suspended matters and then concentrated.
As the preferable technical scheme of the application, the concentration system adopts a low-temperature evaporation method, and can use but not limited to multiple-effect evaporation, MVR evaporation, gas-liquid direct contact evaporation and other forms; a forced circulation mode is adopted, the operating temperature is controlled to be below 85 ℃, and a scale inhibitor and a defoaming agent are required to be added into the system, so that the corrosion and scaling phenomena of equipment and pipelines are avoided; a demister is arranged at a secondary steam outlet of the evaporator to prevent entrainment; after secondary steam is condensed, the COD content of the recovered water is not more than 200mg/L, and the wastewater is further treated by a wastewater treatment unit and discharged after reaching the standard; the salt content of the inlet wastewater of the concentration system is 8-10%, the salt content of the outlet wastewater is 20-25%, sodium carbonate and sodium chloride are taken as main materials, and the total proportion is more than 85%.
As the preferable technical scheme of the application, the concentrated high-concentration salt-containing organic waste liquid is input into an incinerator, and auxiliary fuel and combustion-supporting air are simultaneously input into the incinerator; high-temperature oxidation reaction occurs in the furnace, and organic matters in the waste liquid can be oxidized, decomposed and removed; the high-temperature flue gas in the incinerator is sequentially in direct contact heat exchange with spray water and water in a quenching tank, the temperature is reduced to be below the melting point of inorganic salt, and the inorganic salt and the water form a salt solution; after flue gas is quenched and cooled, waste heat is recovered, and produced steam is used as a heat supply source. The temperature of the outlet flue gas is further reduced, inorganic salt particles and ash content carried in the flue gas are removed, then sulfur dioxide, residual ash content and inorganic salt particles in the flue gas are removed, and finally the flue gas is discharged after reaching the standard; and (4) treating the wastewater discharged by the alkaline tower again.
Wherein, the waste liquid is atomized by low-pressure air, steam or machinery in the incinerator, the incineration temperature is controlled at 1000-1100 ℃, and the retention time is not less than 2 s; after the high-temperature flue gas is sprayed with water and quenched, the temperature of the high-temperature flue gas is reduced to be below 750 ℃, and the temperature of the outlet flue gas is below 200 ℃ after the waste heat is recovered.
Drawings
FIG. 1 is a flow chart of the zero discharge combined treatment process device for desulfurization wastewater and waste lye of the utility model.
Detailed Description
The present invention will be described in further detail with reference to examples. The reagents or instruments used are not indicated by manufacturers, and are regarded as conventional products which can be purchased in the market.
Example 1
A zero-discharge combined treatment process device for desulfurization wastewater and waste lye mainly comprises a pretreatment system, a concentration system, an incineration system and a crystallization system; the pretreatment system, the concentration system, the incineration system and the crystallization system are connected in sequence;
the pretreatment system is provided with a reaction device and a separation unit, the separation unit mainly comprises a solid settling unit and/or a filtering unit, and the waste alkali liquor and the desulfurization wastewater are reacted by the reaction device and then separated into supernatant and solid precipitate by the separation unit;
the concentration system is used for concentrating the supernatant to obtain a concentrated solution;
the incineration system mainly comprises an incinerator, a quenching device, a waste heat recovery device and a post-treatment device, wherein the incinerator, the quenching device, the waste heat recovery device and the post-treatment device are sequentially connected; the incinerator is also connected with a crystallization system through a quenching device;
the crystallization system is used for evaporating and crystallizing the salt solution from the quenching device to obtain crystallized salt and discharging the crystallized salt; the crystallization system is also connected with a waste heat recovery device through a pipeline.
A zero-discharge combined treatment method for desulfurization waste water and waste alkali liquor is characterized in that the waste alkali liquor and the desulfurization waste water are mixed and reacted, then are precipitated and filtered to remove impurities, clear liquid after the impurities are removed enters a concentration system, and salt-containing organic waste water is further concentrated to approach a salting-out point by low-temperature evaporation and then enters an incineration system; carrying out high-temperature oxidation reaction on the high-concentration salt-containing organic waste liquid in an incinerator, decomposing and removing organic matter components completely, and discharging generated high-temperature flue gas through a chimney after carrying out rapid cooling treatment, waste heat recovery, dust removal and alkali washing treatment on the generated high-temperature flue gas to reach the standard; and (4) enabling the salt solution generated after quenching treatment to enter a crystallization system for treatment to obtain crystallized salt for recovery.
Example 2
A zero-discharge combined treatment process device for desulfurization wastewater and waste lye mainly comprises a pretreatment system, a concentration system, an incineration system and a crystallization system; the pretreatment system, the concentration system, the incineration system and the crystallization system are connected in sequence;
the pretreatment system is provided with a reaction device and a separation unit, a pipeline in front of the reaction device is connected with a buffer tank and an oil separation tank, waste alkali liquor is homogenized by the buffer tank, then enters the oil separation tank to remove butter, and then enters the reaction device to react with desulfurization wastewater, so that acid-base neutralization is realized; the separation unit mainly comprises a solid settling unit and a filtering unit, and supernatant and solid precipitate are separated from waste liquid after reaction of the reaction device through the separation unit; the solid settling unit is a settling tank, waste liquid treated by the reaction device is introduced into the settling tank, and a coagulant and a flocculating agent are added to form floc precipitates; the rear part of the sedimentation tank is connected with a concentration tank and a medium filter in parallel, and the rear part of the concentration tank is connected with a filter press; the floc precipitate is further concentrated by a concentration tank and then discharged by a filter press; clear liquid at the upper part of the sedimentation tank enters a medium filter for filtration and then enters a concentration system for treatment; wherein the reaction device is a reaction tank;
the concentration system is used for concentrating the supernatant from the pretreatment system to obtain a concentrated solution; the concentration system is an evaporator system, and the evaporator system is selected from any one of a multi-effect evaporator, an MVR evaporator and a gas-liquid direct evaporator; the evaporator system is provided with a secondary steam outlet, and the secondary steam outlet is provided with a demister to prevent entrainment and avoid the excessive COD of secondary steam condensate.
The incineration system mainly comprises an incinerator, a quenching device, a waste heat recovery device and a post-treatment device, wherein the incinerator, the quenching device, the waste heat recovery device and the post-treatment device are sequentially connected, the post-treatment device mainly comprises a dust remover, an alkaline tower and a chimney, and the dust remover, the alkaline tower and the chimney are sequentially connected; an atomization device is arranged in the incinerator, and the high-concentration salt-containing organic wastewater from the concentration system is sprayed into the incinerator through the atomization device; the incinerator is externally connected with an auxiliary fuel pipeline and a combustion-supporting air pipeline; the incinerator is also connected with a crystallization system through a quenching device, wherein the quenching device is a quenching tank.
The crystallization system is used for evaporating and crystallizing the salt solution from the quenching tank to obtain crystallized salt and discharging the crystallized salt; the crystallization system pipeline is connected with a waste heat recovery device; the crystallization system is provided with a recovery water pipeline, the recovery water pipeline is connected to the quenching tank, and the recovery water obtained after condensation of secondary steam generated by the crystallization system is recycled as spraying water for the flue gas quenching process.
Example 3
Waste alkali liquid generated in the petrochemical production process and desulfurization wastewater discharged in a factory firstly enter a pretreatment unit, the specific treatment process is flexibly selected according to the quality of inlet water, and the pretreatment unit can be provided with equipment and devices such as a buffer tank, an oil separation tank, a reaction tank, a high-efficiency sedimentation tank, a medium filter, a sludge concentration tank, a filter press and the like. The waste alkali liquor firstly enters a buffer tank for homogenization, so that the impact load caused by unstable water quality of inlet water is reduced. And then pumping the waste alkali liquor into an oil separation tank, removing and recovering butter through air floatation, standing and other modes, and reducing the problems of scaling or atomizer blockage caused by polymer generation of a burner in a subsequent incineration system. And stirring and mixing the deoiled waste alkali liquor and the desulfurized wastewater in a reaction tank to realize acid-base neutralization, wherein the pH of the finally mixed wastewater is 8-10. Sulfide, sodium hydroxide and sodium carbonate in the waste alkali liquor react with heavy metal ions and calcium and magnesium hardness ions in the desulfurization waste water to form precipitates. The sulfide in the waste alkali liquor and the heavy metal ions and calcium and magnesium hardness ions in the desulfurization waste water are effectively removed. The reactions involved are as follows:
H++OH-→H2O
Mg2++OH-→Mg(OH)2↓
Ca2++CO3 2-→CaCO3↓
Mx+(heavy Metal ion) + Sy-(sulfide) → MySx(precipitate) ↓
The desulfurization wastewater and the waste alkali liquor both contain more suspended particles, additional precipitate is generated after mixing in a reaction tank, the wastewater after the mixing reaction is pumped into a high-efficiency sedimentation tank, a coagulant and a flocculant are added to accelerate the coagulation and flocculation of the suspended particles, the precipitate, colloidal substances and the like into larger floc precipitate, the floc precipitate is further concentrated by a sludge concentration tank, and finally, a mud cake with the water content of less than 20 percent is formed after the dehydration by a filter press and is transported outside as solid waste. And the supernatant effluent of the high-efficiency sedimentation tank enters a medium filter, and suspended matters are further removed and then pumped into a concentration system. Adding system coagulant of inorganic polymer such as polyaluminium chloride (PAC) or polyferric chloride (PFC) at a dosage of 10-30 mg/L; the coagulant aid is Polyacrylamide (PAM), and the dosage is 1mg/L-5 mg/L. Part of coagulant and coagulant aid can also be added into the system in advance by configuring a pipeline mixer before entering the high-efficiency sedimentation tank. The high-efficiency sedimentation tank is of a conventional type, and is integrated by a coagulation tank, a flocculation tank, a sedimentation tank and sludge concentration, so that the structure is compact. The medium filter can be made of high-quality porous materials such as quartz sand, ceramic plates, activated carbon and the like, and one or more materials are selected to be stacked as a filtering layer.
After the desulfurization wastewater and the waste alkali liquid are treated by the pretreatment system, the pH value of the mixed wastewater is 8-10, the oil content is reduced to be below 5mg/L, the removal rate of COD reaches 20-40%, heavy metal ions are basically removed completely, the calcium and magnesium hardness content is not more than 5mg/L, the content of suspended matters in effluent of a medium filter is not more than 5mg/L, and the salt content of the wastewater is 8-10%.
Mixed wastewater at the outlet of the pretreatment system enters a concentration system for further evaporation and concentration, so that the water content in the wastewater is reduced, the amount of the wastewater entering an incineration system is reduced, and the energy consumption of the incineration system is reduced. The concentration system mainly utilizes a low-temperature evaporation method, and can select forms such as multi-effect evaporation, MVR evaporation, direct gas-liquid contact evaporation and the like. Because the COD content of the wastewater is higher, in order to avoid foaming, equipment pipeline corrosion and scaling phenomena caused by organic matter enrichment in the concentration process, a forced circulation mode is adopted, the maximum operation temperature is controlled below 85 ℃, and a scale inhibitor and a defoaming agent are added into the system. The secondary steam outlet that the evaporation concentration equipment produced sets up the defroster, prevents that the entrainment from smuggleing secretly, leads to secondary steam condensate COD to exceed standard. Because the organic matter content of the waste water is high, even if the operation temperature is controlled to be low, a small amount of organic matter with low boiling point is discharged along with the secondary steam, so that the secondary steam condensate cannot be directly reused as reclaimed water. The COD of the secondary steam condensate is not more than 200mg/L, and the wastewater is discharged after the wastewater is further treated by the wastewater treatment unit to reach the standard. The salt content of the waste water at the outlet of the concentration system is 20-25%, sodium carbonate and sodium chloride are used as main materials, and the total ratio is more than 85%.
The temperature of the waste water at the outlet of the concentration system is 60-80 ℃, and the waste water enters the incineration system for purification treatment. Firstly, high-concentration salt-containing organic wastewater is sprayed into an incinerator through an atomization device, and the atomization device is symmetrically distributed in the incineratorIn the furnace, low pressure air, steam or machinery is used to atomize the waste liquid. And simultaneously, auxiliary fuel and combustion-supporting air are input into the furnace through a pipeline. Under the heat release of the combustion of the auxiliary fuel, the waste water is sprayed into the furnace to generate high-temperature oxidation reaction, the burning temperature is 1000-1100 ℃, the retention time is not less than 2s, the water is directly vaporized, and the organic matter is combusted to generate CO2And H2And O, residual harmful sulfide is burnt and converted into sulfur dioxide, and the inorganic salt forms a molten salt state at a temperature above the melting point. In order to prevent the refractory lining from falling off due to the corrosion of the fused salt to the hearth lining, the incinerator lining can be provided with a wear-resistant refractory corrosion-resistant layer and a heat-insulating refractory heat-insulating layer. The incinerator adopts vertical top-burning side feeding, a quenching tank is arranged below a flue gas outlet, the temperature of high-temperature flue gas is reduced to be below 750 ℃ after water spraying and quenching, and inorganic salt is converted into a solid particle state from a molten salt state and enters the quenching tank to form a salt solution with water. The flue gas temperature after quenching is about 700 ℃, in order to effectively utilize the heat energy of the flue gas, the flue gas enters a waste heat boiler to generate high-temperature high-pressure steam. The waste heat boiler is preferably a single-drum natural circulating water pipe boiler, and a small amount of dust in the flue gas is deposited and discharged from an ash bucket at the lower part of the boiler. The temperature of the flue gas at the outlet of the waste heat boiler is reduced to below 200 ℃, and the flue gas enters a dust remover to remove residual salt particles and dust in the flue gas. The dust collector can be a cloth bag type, an electrostatic type or a Venturi type, and the Venturi type is preferred. And removing sulfur dioxide in the flue gas through an alkaline tower, wherein a demister is arranged at the outlet of the alkaline tower, and water carried in the flue gas is further separated and then discharged into the atmosphere through a chimney. And pumping the wastewater discharged by the alkaline tower into a reaction tank of the pretreatment system through a pipeline.
The concentration of the salt solution obtained in the quenching tank of the incineration system is controlled to be 30-40%, and the main components are sodium carbonate and sodium chloride. The salt solution is pumped into a crystallization system for treatment, a heating source of the crystallization system is steam generated by a waste heat boiler, and secondary steam generated by the crystallization system is condensed to obtain recovered water which is recycled as spray water for a flue gas quenching process. The crystallization system can adopt multiple-effect evaporation crystallization and MVR evaporation crystallization forms to obtain crystallized miscellaneous salt for recycling. Or further adopting a quality-divided crystallization process to respectively recover sodium chloride and sodium carbonate, thereby realizing resource recycling of the salt.
Example 4
A chemical industry park has a strand of waste alkali liquor of an ethylene device, the water quantity is 1t/h, the water quality indexes are that the mass percentage of NaOH is 1.5 percent and Na2CO37 percent, 1 percent of sulfide, more than 13 pH, 1500mg/L-2000mg/L of BOD, 10000 mg/L-15000 mg/L of COD, 100mg/L-250mg/L of phenols and 500mg/L-800mg/L of free oil. In addition, a stream of desulfurized wastewater with the water amount of 10m exists3The water quality index is pH 4.5, TDS about 50000mg/L, COD about 200mg/L, SS about 10000mg/L, hardness about 8000mg/L, chloride ion about 30000mg/L, sulfate radical about 4000mg/L, and heavy metal ion about 50 mg/L.
The ethylene device alkali waste firstly enters a buffer tank, then is pumped into an oil separation tank by the buffer tank, compressed gas is introduced into the oil separation tank, the air flotation principle and the standing effect are utilized, the alkali waste liquid is layered, an upper butter layer is taken for recycling, the residual alkali waste liquid is pumped into a reaction tank, the other strand of desulfurization waste water is also pumped into the reaction tank, and the two strands of waste water react under the stirring effect, wherein the acid-base reaction and the precipitation reaction exist. The hardness ions such as calcium and magnesium and the like and the heavy metal ions in the desulfurization wastewater react with the sodium hydroxide, the sodium carbonate and the sulfide in the waste alkali liquor to generate CaCO3、Mg(OH)2And sulfide heavy metal precipitates and the like, the removal rate of hardness ions is high, and the heavy metal ions are basically removed. Pumping the suspension in the reaction tank into a high-efficiency sedimentation tank, adding a coagulant of polyaluminium chloride and a flocculant of polyacrylamide, accelerating the aggregation of suspended particles, sediments, colloids and other substances in the high-efficiency sedimentation tank into floccules, and depositing the floccules at the bottom. Further concentrating by a sludge concentration tank, and dehydrating by a filter press to obtain a sludge cake for outward transportation of solid wastes. And the clear liquid discharged from the upper layer of the high-efficiency sedimentation tank is pumped to low-temperature evaporation concentration equipment after suspended matters are removed by a medium filter. The pH value of the wastewater entering the low-temperature evaporation concentration equipment is about 9, the SS is about 5mg/L, the free oil is about 5mg/L, the COD is 800mg/L-1200mg/L, and the salt content is about 8%.
The low-temperature evaporation concentration system adopts a gas-liquid direct contact evaporation mode, waste liquid is preheated to 60-80 ℃ and then is sprayed into an evaporation chamber from top to bottom through a spraying system, circulating cold air flow is blown from bottom to top, so that the cold air is fully contacted with waste water, after the cold air and the waste water are subjected to heat exchange and temperature rise, 3-12% of water flowing downwards is absorbed to form moisture-containing air flow, water in the waste liquid is taken out, the moisture-containing air flow acts on a condensation chamber through a condenser, and water vapor is condensed into a water discharge system. Because the condensed water contains a small amount of COD, the condensed water is directly pumped to sewage treatment and is discharged after reaching the standard. The salt content of the waste water at the outlet of the low-temperature evaporation concentration equipment is controlled to be 20-25%, sodium carbonate and sodium chloride salt are mainly used, and the total ratio is about 90%.
And (3) pumping the concentrated waste liquid into an incinerator, inputting auxiliary fuel natural gas and combustion-supporting air through a pipeline, carrying out high-temperature oxidation reaction on the waste liquid in the incinerator, controlling the incineration temperature to be about 1100 ℃, keeping the time for 2s, completely decomposing organic matters in the waste water, and incinerating residual sulfides at high temperature to generate sulfur dioxide. The incinerator adopts vertical top-burning side feeding, the temperature of a high-temperature flue gas outlet is reduced to 700 ℃ after water spraying and quenching, inorganic salt in the flue gas is changed into solid from molten state, and the inorganic salt enters a quenching tank to form a salt solution with water. And (4) introducing the quenched flue gas into a waste heat boiler to obtain a byproduct of 0.8MPa steam. The waste heat boiler adopts a water pipe type, and the temperature of outlet flue gas is about 180 ℃. And then enters a bag-type dust collector to remove dust and inorganic salt particles in the smoke. Then enters an alkaline tower to remove sulfur dioxide in the flue gas, a demister is arranged at a flue gas outlet of the alkaline tower to remove moisture in the flue gas, and the flue gas is discharged out of a chimney after reaching the standard. The alkaline washing liquid is 10% NaOH solution, and the wastewater discharged by the alkaline washing tower is pumped into the reaction tank.
Pumping into an evaporative crystallization device when the concentration of the salt solution in the quenching tank reaches 35%, adopting a forced circulation MVR evaporative crystallizer, taking the byproduct of 0.8MPa steam of the waste heat boiler as a heating source, and crystallizing to obtain miscellaneous salts, wherein the main components are sodium carbonate and sodium chloride. And condensing secondary steam generated in the evaporation crystallization process and recycling the secondary steam as spray water of a quenching process.
The protection of the present invention is not limited to the above embodiments. Variations and advantages that may occur to those skilled in the art may be incorporated into the invention without departing from the spirit and scope of the inventive concept, and the scope of the appended claims is intended to be protected.
Claims (12)
1. A desulfurization waste lye zero discharge combined treatment process device is characterized by mainly comprising a pretreatment system, a concentration system, an incineration system and a crystallization system; the pretreatment system, the concentration system, the incineration system and the crystallization system are connected in sequence;
the pretreatment system is provided with a reaction device and a separation unit, the separation unit mainly comprises a solid settling unit and/or a filtering unit, and the waste alkali liquor and the desulfurization wastewater are reacted by the reaction device and then separated into supernatant and solid precipitate by the separation unit;
the concentration system is used for concentrating the supernatant to obtain a concentrated solution;
the incineration system mainly comprises an incinerator, a quenching device, a waste heat recovery device and a post-treatment device, wherein the incinerator, the quenching device, the waste heat recovery device and the post-treatment device are sequentially connected; the incinerator is also connected with a crystallization system through a quenching device;
the crystallization system is used for evaporating and crystallizing the salt solution from the quenching device to obtain crystallized salt and discharging the crystallized salt; the crystallization system is also connected with a waste heat recovery device through a pipeline.
2. The zero-discharge combined treatment process device for the desulfurization waste lye as claimed in claim 1, wherein the front pipeline of the reaction device is connected with a buffer tank and an oil-separating tank.
3. The zero-emission combined treatment process device for desulfurization waste alkali solution according to claim 1, characterized in that the solid settling unit is a settling tank; the back of the sedimentation tank is connected with a concentration tank and a medium filter in parallel, and the back of the concentration tank is connected with a filter press.
4. The zero-emission combined treatment process device for desulfurization waste alkali liquor as claimed in claim 2, wherein the solid settling unit is a settling tank; the back of the sedimentation tank is connected with a concentration tank and a medium filter in parallel, and the back of the concentration tank is connected with a filter press.
5. The zero-emission combined treatment process device for the desulfurization waste alkali liquor as claimed in any one of claims 1 to 4, wherein the post-treatment device mainly comprises a dust remover, an alkaline tower and a chimney, and the dust remover, the alkaline tower and the chimney are connected in sequence.
6. The zero-discharge combined treatment process device for desulfurization waste lye of claim 1, wherein the crystallization system is provided with a recovery water pipeline, and the recovery water pipeline is connected to the quenching tank.
7. The zero-emission combined treatment process device of desulfurization waste lye of claim 1, characterized in that the concentration system is an evaporator system.
8. The zero-emission combined treatment process device for desulfurization waste lye of claim 7, wherein the evaporator system is a low temperature evaporator system.
9. The zero-emission combined treatment process device of desulfurization waste lye of claim 8, wherein the low temperature evaporator system is selected from any one of a multi-effect evaporator, an MVR evaporator and a gas-liquid direct contact evaporator.
10. The zero-discharge combined treatment process device for the desulfurization waste lye of claim 7, wherein the evaporator system is provided with a secondary steam outlet, and the secondary steam outlet is provided with a demister.
11. The zero-emission combined treatment process device of desulfurization waste lye as claimed in claim 1, wherein an atomization device is provided in said incinerator.
12. The zero-emission combined treatment process device for the desulfurization waste alkali liquor as claimed in claim 1 or 11, wherein the incinerator is externally connected with an auxiliary fuel pipeline and a combustion air pipeline.
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