System and method for deeply recycling urban reclaimed water into industrial water of thermal power plant
Technical Field
The invention belongs to the technical field of water treatment, and particularly relates to a system and a method for deeply recycling urban reclaimed water into industrial water of a thermal power plant.
Background
In recent years, with the progress of national industrialization and urbanization, the electricity consumption in the country is continuously increased. At present, the main power generation mode in China is thermal power generation, and the thermal power generation accounts for more than 70% of the total power generation capacity in China. The mode of generating electricity by using energy contained in combustible materials and the like is generally called thermal power generation, and according to the power generation mode, thermal power generation is divided into coal-fired steam turbine power generation and oil-fired steam turbine power generation. Thermal power plant sites are required to consume large amounts of water resources to maintain normal production demands. The water resource distribution in south and north of China is differentiated, the water resource in south is rich, industrial water of a thermal power plant is mostly collected from surface water such as rivers and lakes, but because the daily water intake is large, huge burden is still brought to the natural environment; water resources in northern areas are short, and the thermal power plants constructed in northern water-deficient areas mostly introduce reclaimed water treated by municipal sewage treatment plants on the spot to be used as industrial water sources.
Most industrial water of a thermal power plant is used for a circulating water system, the requirement of the part of water on water quality is relatively low, the reclaimed water discharged after the standard extraction of a sewage treatment plant in the existing reclaimed water reuse technology can be directly used for water supplement of a cooling tower and the like through conventional treatment, but most of the supplemented water of a boiler steam-water system with extremely strict requirement on water quality is still taken from surface water, underground water or desalted water obtained after seawater desalination, so that the water taking cost is high, and the maintenance cost of equipment with complicated treatment process is also quite high.
An aeration biological fluidization pool (ABFT for short) sewage treatment technology is a new sewage treatment technology for removing ammonia nitrogen by a biochemical method in recent years, and an ABFT reactor is actually a double-bioreactor integrating the advantages of the traditional activated sludge method and a biofilm method. In each stage of ABFT reactor, the degradation effect of the target pollutants is improved by culturing different strains with special effects and advantages; the highest biomass of the growing carrier can reach 10 g/L-18 g/L, the combination of the survived microorganisms and the carrier adopts a bond-valence combined immobilization technology, so the combination force is firm, the microorganisms are not easy to fall off and run off, and the high-load biomass ensures the high efficiency and stability of the ABFT reactor in removing pollutants. Ultraviolet light with the wavelength of less than 200nm emitted by a high-energy ultraviolet lamp is utilized for ultraviolet sterilization and disinfection, water can be subjected to photodecomposition to generate hydroxyl radicals with extremely high energy, the hydroxyl radicals can react with organic compounds, and TOC of the effluent can be controlled at a very low level by removing the organic compounds through ultraviolet light irradiation.
Electrodialysis is a mature technology in the membrane separation process and is widely applied to brackish water desalination, and the newly developed charged membrane has higher selectivity, lower membrane resistance, better chemical stability and higher mechanical strength, so that the electrodialysis technology can be applied to the reduction work of the desulfurization wastewater of the power plant with poor water quality.
Nanofiltration (NF) separation is a green water treatment technology, can replace the traditional sewage treatment method with high cost and complex process in some aspects, and can intercept organic matters with molecular weight more than 100 and multivalent ions through the specific properties of the nanofiltration membrane, and only allows small-molecular organic matters and monovalent ions to permeate.
In order to make the industrial water system of the power plant have good environmental benefit and economic benefit and meet the national policies of water saving and environmental protection, a more green and economic water taking mode is needed to meet the requirements of industrial production.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provides a system and a method for deeply recycling urban reclaimed water into industrial water of a thermal power plant.
The system for deeply recycling the urban reclaimed water into the industrial water of the thermal power plant comprises the following steps: the system comprises an ABFT biochemical treatment tank, an intermediate water tank, a muddy water well, an accelerated clarification tank, a clean water well, a circulating water system, a cooling tower, a boiled cold water pump, an industrial miscellaneous water pipeline, an ultraviolet disinfection tank, a filter A, an ultrafiltration system, a reverse osmosis system, a cation-anion mixed bed, a desalting water tank, a boiler steam-water system, water treatment regeneration equipment, a hydrogen station, a chemical laboratory, a fine treatment regeneration wastewater tank, a stripping rectification denitrification device, a chemical regeneration wastewater tank, a filter B, a nanofiltration device, a power plant desulfurization wastewater tank, an electrodialysis system and a drying tower;
the water inlet pipeline of the ABFT biochemical treatment tank is connected with a water outlet pipeline of a sewage treatment plant, the water outlet pipeline of the ABFT biochemical treatment tank is connected with a water inlet pipeline of an intermediate water tank, the water outlet pipeline of the intermediate water tank is connected with a water inlet pipeline of a muddy water well, the water outlet pipeline of the muddy water well is connected with a water inlet pipeline of an accelerated clarification tank, and the water outlet pipeline of the accelerated clarification tank is connected with a water inlet pipeline of a clean water well; the water outlet pipeline of the clean water well is divided into two paths, wherein one path of water outlet pipeline is connected with a water inlet pipeline of the circulating water system, and the other path of water outlet pipeline is connected with a water inlet pipeline of the ultraviolet disinfection pool; the water outlet pipeline of the circulating water system is divided into three paths and is respectively connected with a water inlet pipeline of the cooling tower, a boiled cold water pump pipeline and an industrial miscellaneous water pipeline; the water outlet pipeline of the ultraviolet disinfection tank is connected with the water inlet pipeline of the filter A, the water outlet pipeline of the filter A is connected with the water inlet pipeline of the ultrafiltration system, and the water outlet pipeline of the ultrafiltration system is connected with the water inlet pipeline of the reverse osmosis system; the water outlet pipeline of the reverse osmosis system is divided into two paths and is respectively connected with the water inlet pipeline of the yin-yang mixed bed and the water inlet pipeline of the ABFT biochemical treatment pool; the water outlet pipeline of the yin-yang mixed bed is divided into two paths to be respectively connected with the water inlet pipeline of the chemical regeneration waste water tank and the water inlet pipeline of the demineralized water tank;
the water outlet pipeline of the demineralized water tank is divided into four paths and is respectively connected with a water inlet pipeline of a chemical laboratory, a water inlet pipeline of a hydrogen station, a water inlet pipeline of water treatment regeneration equipment and a water inlet pipeline of a boiler steam-water system; the water outlet pipeline of the boiler steam-water system is connected with the water inlet pipeline of the wastewater treatment and regeneration tank, the water outlet pipeline of the wastewater treatment and regeneration tank is connected with the water inlet pipeline of the denitrification device by steam stripping rectification, and the water outlet pipeline of the denitrification device is connected with the water inlet pipeline; the water outlet pipeline of the chemical regeneration waste water tank is connected with the water inlet pipeline of the filter B, and the water outlet pipeline of the filter B is connected with the water inlet pipeline of the nanofiltration device; the water outlet pipeline of the nanofiltration device is connected with the water inlet pipeline of the drying tower;
an outlet pipeline of the power plant desulfurization wastewater pool is connected with an inlet pipeline of the electrodialysis system, and an outlet pipeline of the electrodialysis system is connected with a water inlet pipeline of the drying tower.
Preferably, the inside of the ABFT biochemical treatment tank is divided into a decarbonization area, a high-speed nitrification area, a medium-speed nitrification area and a low-speed nitrification area; wastewater in the ABFT biochemical treatment tank firstly passes through the decarbonization zone, then passes through the high-speed nitrification zone, then enters the medium-speed nitrification zone, and finally flows through the low-speed nitrification zone.
Preferably, the biochemical treatment tank is also provided with an air blower.
Preferably, the middle water tank is connected with the muddy water well through a centrifugal pump, and the muddy water well is also provided with a matched coagulant dosing device.
Preferably, a treatment digestion module is further arranged in the boiler steam-water system.
The working method of the system for deeply recycling the urban reclaimed water into the industrial water of the thermal power plant specifically comprises the following steps:
step 1, delivering effluent of a sewage treatment plant into an ABFT biochemical treatment tank in a power plant through a lifting water pump and a pipeline system, and performing biochemical treatment through a decarbonization area, a high-speed nitrification area, a medium-speed nitrification area and a low-speed nitrification area of the ABFT biochemical treatment tank; the water outlet of the ABFT biochemical treatment tank is lifted to a muddy water well by a centrifugal pump through an intermediate water tank, a coagulant dosing device matched with the muddy water well is utilized to add a medicament, the water outlet of the muddy water well automatically flows into a mechanical accelerated clarification tank for sedimentation treatment, and clear water after sedimentation treatment flows into a clear water well;
step 2, recycling one path of outlet water of the clean water well to a circulating water system, wherein the circulating water system mainly supplies water for the cooling tower, and the outlet water of the path simultaneously supplies a boiled cold water pump and industrial miscellaneous water; the other path of effluent of the clean water well firstly carries out advanced treatment on water quality, then is used for supplementing water to a boiler steam-water system, enters an ultraviolet disinfection tank, is subjected to ultraviolet disinfection to remove bacteria and organic matters in water and reduce TOC, then is filtered by a filter A, is pressurized by a pressure pump and then enters an ultrafiltration system to remove macromolecular particles in water, then is pressurized again to enter a reverse osmosis system, so that the desalination rate of the effluent reaches more than 98 percent, reverse osmosis concentrated water generated in the reverse osmosis system is transported back to an ABFT biochemical treatment tank for treatment, and other produced water of the reverse osmosis system is lifted by a centrifugal pump and then enters a cation-anion mixed bed (sequentially enters an cation bed, an anion bed and a mixed bed) for further desalination, so that the final produced water quality reaches the desalination water standard specified in GB/T12145 plus 2016; the effluent of the anion-cation mixed bed enters a desalting water tank and a chemical regeneration wastewater tank;
step 3, the desalting water tank is mainly used for supplying water for a steam-water system of the boiler, and simultaneously supplies water for water treatment regeneration equipment, a hydrogen station and a chemical laboratory; the fine treatment regeneration wastewater obtained by the boiler steam-water system through the treatment of the digestion module flows into a fine treatment regeneration wastewater tank, and the fine treatment regeneration wastewater contains a large amount of NH3-N; after denitrogenation of the refined treatment regenerated wastewater in the refined treatment regenerated wastewater tank by a stripping rectification denitrogenation device, the refined treatment regenerated wastewater is combined with the chemical regenerated wastewater after insoluble substances in the chemical regenerated wastewater tank are filtered by a filter B, and then the chemical regenerated wastewater is pressurized by a pressure pump and enters a nanofiltration device for classification;
and 4, concentrating and reducing the desulfurization wastewater in the power plant desulfurization wastewater pool through an electrodialysis system, combining the desulfurization wastewater with the effluent of the nanofiltration device, introducing the mixture into a drying tower, evaporating the tail end wastewater in the drying tower through a bypass flue evaporation technology, and collecting and transporting residual ash and slag together.
Preferably, in step 1, when the ABFT biochemical treatment tank is subjected to biochemical treatment: oxygen required by the biochemical process is fed into a decarbonization area, a high-speed nitrification area, a medium-speed nitrification area and a low-speed nitrification area in the biochemical treatment tank by adopting a proper blower, various pollution factors in the sewage are degraded under the action of microorganisms and nitrifying bacteria in the sewage, and particularly, ammonia nitrogen in the sewage is effectively removed through nitrification.
Preferably, in the step 1, the effluent of the sewage treatment plant is conveyed to an ABFT biochemical treatment tank in the power plant through a lifting water pump and a pipeline system.
The invention has the beneficial effects that:
the invention provides a system for deeply recycling urban reclaimed water into industrial water of a thermal power plant, which creatively introduces reclaimed water discharged from a sewage treatment plant into a plant area for treatment, then uses one part of the treated reclaimed water for a circulating water system, and uses the other part of the treated reclaimed water for water supplement of a boiler steam-water system after continuous advanced treatment, and simultaneously, wastewater generated in the operation process of the system is concentrated and reduced and then is evaporated to dryness in a drying tower so as to achieve no wastewater discharge.
The industrial water of the thermal power plant is all taken from the reclaimed water source treated by the sewage treatment plant, and zero water taking from the ground surface is realized. The ABFT process is applied to reclaimed water treatment, so that the effluent meets the water demand of a circulating water system in a plant area, and the effluent can meet the water supplementing and water quality requirements of a steam-water system of a boiler after advanced treatment.
The invention applies the ultraviolet disinfection and sterilization technology to the water treatment process of the thermal power plant for the first time, replaces the traditional chemical dosing method, effectively avoids the introduction of toxic substances and the damage of residual chlorine to the subsequent membrane component, reduces the environmental pollution and saves the cost at the same time.
The tail end wastewater including chemical regeneration wastewater, fine treatment regeneration wastewater and concentrated and reduced desulfurization wastewater generated in the operation process is concentrated and then uniformly sent to a bypass flue drying system to be evaporated to dryness, and the residual ash containing substances such as salt and the like is concentrated and sold out, so that the problem of treating the wastewater is effectively solved by using the waste heat of the flue gas.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Description of reference numerals: the system comprises a sewage treatment plant 1, an ABFT biochemical treatment tank 2, a middle water tank 3, a muddy water well 4, an accelerated clarification tank 5, a clean water well 6, a circulating water system 7, a cooling tower 71, a boiled water pump pipeline 72, an industrial miscellaneous water pipeline 73, an ultraviolet disinfection tank 8, a filter A9, an ultrafiltration system 10, a reverse osmosis system 11, a mixed anion-cation bed 12, a demineralized water tank 13, a boiler steam-water system 131, a water treatment regeneration device 132, a hydrogen station 133, a chemical laboratory 134, a fine treatment regeneration wastewater tank 14, a stripping rectification denitrification device 15, a chemical regeneration wastewater tank 16, a filter B17, a nanofiltration device 18, a power plant desulfurization wastewater tank 19, an electrodialysis system 20 and a drying tower 21.
Detailed Description
The present invention will be further described with reference to the following examples. The following examples are set forth merely to aid in the understanding of the invention. It should be noted that, for a person skilled in the art, several modifications can be made to the invention without departing from the principle of the invention, and these modifications and modifications also fall within the protection scope of the claims of the present invention.
Example 1:
as shown in fig. 1, a system for deep reuse of urban reclaimed water as industrial water of a thermal power plant comprises: an ABFT biochemical treatment tank 2, a middle water tank 3, a muddy water well 4, an accelerated clarification tank 5, a clean water well 6, a circulating water system 7, a cooling tower 71, a boiled cold water pump 72, an industrial miscellaneous water pipeline 73, an ultraviolet disinfection tank 8, a filter A9, an ultrafiltration system 10, a reverse osmosis system 11, a mixed anion-cation bed 12, a demineralized water tank 13, a boiler steam-water system 131, water treatment regeneration equipment 132, a hydrogen station 133, a chemical laboratory 134, a fine treatment regeneration wastewater tank 14, a stripping rectification denitrification device 15, a chemical regeneration wastewater tank 16, a filter B17, a nanofiltration device 18, a power plant desulfurization wastewater tank 19, an electrodialysis system 20 and a drying tower 21;
wherein the water inlet pipeline of the ABFT biochemical treatment tank 2 is connected with the water outlet pipeline of the sewage treatment plant 1, the water outlet pipeline of the ABFT biochemical treatment tank 2 is connected with the water inlet pipeline of the intermediate water tank 3, the water outlet pipeline of the intermediate water tank 3 is connected with the water inlet pipeline of the muddy water well 4, the water outlet pipeline of the muddy water well 4 is connected with the water inlet pipeline of the accelerated clarification tank 5, and the water outlet pipeline of the accelerated clarification tank 5 is connected with the water inlet pipeline of the clear water well 6; the water outlet pipeline of the clean water well 6 is divided into two paths, wherein one path of water outlet pipeline is connected with the water inlet pipeline of the circulating water system 7, and the other path of water outlet pipeline is connected with the water inlet pipeline of the ultraviolet disinfection tank 8; the water outlet pipeline of the circulating water system 7 is divided into three paths and is respectively connected with the water inlet pipeline of the cooling tower 71, the boiled cold water pump pipeline 72 and the industrial miscellaneous water pipeline 73; the water outlet pipeline of the ultraviolet disinfection tank 8 is connected with the water inlet pipeline of the filter A9, the water outlet pipeline of the filter A9 is connected with the water inlet pipeline of the ultrafiltration system 10, and the water outlet pipeline of the ultrafiltration system 10 is connected with the water inlet pipeline of the reverse osmosis system 11; the water outlet pipeline of the reverse osmosis system 11 is divided into two paths and is respectively connected with the water inlet pipeline of the yin-yang mixed bed 12 and the water inlet pipeline of the ABFT biochemical treatment pool 2; the water outlet pipeline of the anion-cation mixed bed 12 is divided into two paths to be respectively connected with the water inlet pipeline of the chemical regeneration wastewater tank 16 and the water inlet pipeline of the demineralized water tank 13; the inside of the ABFT biochemical treatment tank 2 is divided into a decarbonization area, a high-speed nitrification area, a medium-speed nitrification area and a low-speed nitrification area; the biochemical treatment tank 2 is also internally provided with an air blower; the middle water tank 3 is connected with a muddy water well 4 through a centrifugal pump, and the muddy water well 4 is also provided with a matched coagulant adding device;
the water outlet pipeline of the demineralized water tank 13 is divided into four paths to be respectively connected with a water inlet pipeline of a chemical laboratory 134, a water inlet pipeline of a hydrogen station 133, a water inlet pipeline of water treatment regeneration equipment 132 and a water inlet pipeline of a boiler steam-water system 131; the water outlet pipeline of the boiler steam-water system 131 is connected with the water inlet pipeline of the refined treatment and regeneration wastewater tank 14, the water outlet pipeline of the refined treatment and regeneration wastewater tank 14 is connected with the water inlet pipeline of the stripping rectification denitrification device 15, and the water outlet pipeline of the denitrification device 15 is connected with the water inlet pipeline of the water outlet pipeline 18; the water outlet pipeline of the chemical regeneration wastewater tank 16 is connected with the water inlet pipeline of the filter B17, and the water outlet pipeline of the filter B17 is connected with the water inlet pipeline of the nanofiltration device 18; the water outlet pipeline of the nanofiltration device 18 is connected with the water inlet pipeline of the drying tower 21; the boiler steam-water system 131 is also provided with a treatment digestion module;
an outlet pipeline of the power plant desulfurization wastewater tank 19 is connected with an inlet pipeline of an electrodialysis system 20, and an outlet pipeline of the electrodialysis system 20 is connected with a water inlet pipeline of a drying tower 21.
Example 2:
the ABFT process has the advantages of high removal rate, short biochemical reaction time and NH resistance in the comprehensive utilization engineering of advanced treatment of urban reclaimed water3strong-N load hydraulic impact capability, low operation cost and the like, and the effluent stability is superior to various index requirements of reclaimed water reuse.
Incoming water in a sewage treatment plant 1 is directly introduced into an ABFT biochemical treatment tank 2 for denitrification, the effluent sequentially passes through an intermediate water tank 3, a muddy water well 4 and an accelerated clarification tank 5 and finally reaches a clear water well 6, and chemicals such as a flocculating agent, a coagulant aid and the like are added between the muddy water well 4 and the accelerated clarification tank 5. The water from clean water well 6 is supplied to the circulating water system 7 of power plant, and the water source is sent to cooling tower 71, boiled water pump pipeline 72 and industrial water pipeline 73. The residual effluent of the clean water well 6 is used for supplying a chemical water production process, firstly, ultraviolet disinfection is carried out in an ultraviolet disinfection tank 8, and then the residual effluent enters a desalting water tank 13 after passing through a filter A9, an Ultrafiltration (UF) system 10, a Reverse Osmosis (RO) system 11 and a yin-yang mixed bed 12 in sequence; the water source of the desalted water tank 13 goes to a boiler steam-water system 131, a water treatment equipment regeneration 132, a hydrogen station 133 and a chemical laboratory 134, and the reverse osmosis RO concentrated water is transported back to the ABFT biochemical treatment tank 2 for treatment.
The refined treatment regeneration wastewater generated in the boiler steam-water system 131 is stored in a refined treatment regeneration wastewater tank 14, the chemical regeneration wastewater generated in the chemical water production process is stored in a chemical regeneration wastewater tank 16, the refined treatment regeneration wastewater subjected to denitrification by the stripping rectification method in a stripping rectification method denitrification device 15 is combined with the chemical regeneration wastewater subjected to insoluble matter filtration by a filter B17, and the combined wastewater is pressurized by a pressure pump and then enters a nanofiltration device 18 for classification. The desulfurization wastewater in the power plant desulfurization wastewater pool 19 is concentrated and reduced by the electrodialysis system 20, then is combined with the outlet water of the nanofiltration system, and enters the drying tower 21, the tail end wastewater is evaporated in the drying tower 21 by a bypass flue evaporation technology, and the residual ash is collected and transported outside.
The urban reclaimed water deep recycling system is successfully put into production and applied to a certain thermal power plant in the south, and the water taking condition of the thermal power plant in the south after adopting the system (reclaimed water deep recycling system) for taking urban reclaimed water as industrial water of the thermal power plant is shown in the following table 1:
TABLE 1 situation of water taken after the system for recycling reclaimed water in deep level of example 1 is adopted in certain thermal power plant in south China
The plant has an agreement with a local sewage treatment plant, and the total water intake is 2128.7 t/h.
Municipal sewage which is discharged after reaching the standard is directly introduced into a plant area and enters an ABFT water purification system, the system adopts a novel biological carrier synthesized by NC-5ppi type high polymer materials and nitrobacteria-II high-efficiency broad-spectrum dominant nitrifying bacteria, and the combination has the advantages of strong adaptability, large load capacity, capability of purifying and maintaining dominant flora and the like. PAC is added at the position of a pipeline mixer of the middle water tank connected with the muddy water well, and PAM is added at the position of the muddy water well for coagulation. The ultrafiltration membrane module adopts the type of Asahi chemical synthesis UNA-620A, and the reverse osmosis membrane module adopts the type of Dow BW30 FR-400/34. Effluent water quality index: NH (NH)3The average concentration of N is 0.35mg/L and is lower than 1mg/L of the water quality requirement of a power plant; the average concentration of CODcr is 19.6mg/L, which is lower than 60mg/L required by the water quality of a power plant. The ABFT first-stage engineering treatment capacity is 1060.4t/h, and the second-stage treatment capacity is 1068.3 t/h. The amount of water supplemented to the cooling tower in the circulating cooling water system is 1175t/h, the amount of water supplemented to the boiled water system is 418t/h, and the amount of water used for industrial service water is 323.3 t/h. The water quantity of the demineralized water tank for supplementing the water to the steam water of the boiler is 190.5t/h, and the water quantity of the demineralized water tank for finely processing the regeneration water is 5 t/h. The total amount of the chemical regeneration wastewater and the fine treatment regeneration wastewater is 14.5 t/h. The total amount of the tail end wastewater treated by the flue evaporation technology is 7.5 t/h.