Novel method for performing zero-discharge treatment on wet desulphurization wastewater by utilizing cyclone separator of circulating fluidized bed boiler

Abstract

According to the novel method for performing zero-emission treatment on the wet desulfurization wastewater by using the cyclone separator of the circulating fluidized bed boiler, the circulating fluidized bed boiler, the cyclone separator of the circulating fluidized bed boiler, a material returning dipleg, a double-fluid spray gun, a wastewater tank, a wastewater conveying pump A and a wastewater conveying pump B are adopted. On the basis of overcoming the defects in the prior art, a novel desulfurization wastewater zero-discharge treatment route is provided by utilizing the cyclone separator of the circulating fluidized bed boiler, and the method has the characteristics of high cooperative treatment efficiency, simple and reliable system, low investment cost, low energy consumption and cost, stable treatment effect, high process adaptability and capability of treating waste with waste; the low-cost zero-emission treatment of the desulfurization wastewater is efficiently realized, and the reliability and the safety of the treatment system are greatly improved.

Description

Technical Field

[0001] The present invention relates to a novel method for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator, and more particularly to a novel method for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator, comprising a circulating fluidized bed boiler, a circulating fluidized bed boiler cyclone separator, a return leg, a dual-fluid spray gun, a wastewater tank, a wastewater delivery pump A, and a wastewater delivery pump B. The present invention relates to the field of zero-discharge desulfurization wastewater, and is applicable to a system for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator. Background Art

[0002] Thermal power plants typically use a limestone-gypsum wet flue gas desulfurization system, which generates wastewater. Desulfurization wastewater is one of the most difficult wastewaters to treat in thermal power plants. As high in salt, chloride, and heavy metals, it is difficult to recycle. Desulfurization wastewater not only causes clogging and corrosion in reuse and treatment facilities, but also causes long-term pollution to surface water, soil, and groundwater.

[0003] The goal of zero-discharge desulfurization wastewater treatment is to eliminate water and soil pollution from high-salt, highly pollutant wastewater, and to prevent the release of harmful substances such as heavy metals that harm the ecology and human health. Its significance lies in fulfilling environmental regulations, promoting green transformation in industries like thermal power, achieving water recycling, contributing to the "dual carbon" goals, and promoting sustainable development.

[0004] Zero-discharge technology for desulfurization wastewater requires a multi-stage treatment process chain. The mainstream technical approach can be summarized as "pretreatment + concentration reduction + terminal solidification." The pretreatment goal is to remove suspended solids (SS), hardness ions (Ca²⁺, Mg²⁺), heavy metals, and organic matter to prevent scaling and contamination in subsequent systems. Currently, mainstream processes include traditional three-tank processes and integrated treatment processes.

[0005] The concentration and reduction process can reduce wastewater volume by 70-90%, significantly lowering the cost of final curing. Based on the process principle, it can be divided into two categories: membrane and thermal methods.

[0006] End curing is the final step in achieving zero emissions, and its core technologies include evaporation crystallization and flue gas evaporation.

[0007] Flue gas evaporation technology includes low-temperature drying of the main flue and high-temperature solidification technology of the bypass flue. Currently, these technology combinations are used in various domestic power plants, but the investment and operating costs are generally high.

[0008] The current zero-discharge technology for desulfurization wastewater has the following shortcomings and problems that need to be improved: high treatment costs, high energy consumption in processes such as evaporation and crystallization, and high equipment investment and operation and maintenance costs; the system is prone to scaling and clogging, and the high salt and high hardness components in the wastewater cause serious wear and corrosion of pipes and equipment, affecting the stability of the treatment system operation; the by-products (such as salt) are of insufficient purity, making resource utilization difficult and potentially causing secondary disposal problems.

[0009] The current technical difficulties faced by zero-emission desulfurization wastewater technology are: pretreatment is difficult, and suspended solids, heavy metals and complex organic matter in the wastewater need to be efficiently removed, otherwise it will affect the subsequent process; the concentration efficiency of high-salt and high-concentration water is low; the crystallized salt separation and purification technology is immature and difficult to meet industrial-grade standards, which restricts the resource utilization process.

[0010] This invention, while overcoming the shortcomings of existing technologies, utilizes a circulating fluidized bed boiler cyclone separator to propose a novel zero-discharge treatment route for desulfurization wastewater. This route features high synergistic treatment efficiency, a simple and reliable system, low investment costs, low energy consumption and costs, stable treatment results, strong process adaptability, and the ability to "treat waste with waste." This allows for efficient, low-cost, zero-discharge treatment of desulfurization wastewater, significantly improving the reliability and safety of the treatment system. The core innovations and technical advantages of this invention are primarily reflected in:

[0011] (1) High efficiency of collaborative treatment: Relying on the high temperature environment (usually 800℃-950℃) of the circulating fluidized bed boiler cyclone separator, the desulfurization wastewater can be directly sprayed into the inlet area of ​​the circulating fluidized bed boiler cyclone separator, and the waste heat of the flue gas can be used to achieve rapid evaporation of water. At the same time, the salt, heavy metals, etc. in the wastewater are solidified at high temperature, eliminating the need for separate evaporation equipment and simplifying the process.

[0012] (2) Low energy consumption and cost: No additional large amount of heat source is required. The waste heat of flue gas from the cyclone separator of the circulating fluidized bed boiler can be directly utilized to reduce the energy consumption and equipment investment of the traditional evaporation crystallization process. It is suitable for system integration with the existing circulating fluidized bed boiler.

[0013] (3) Stable treatment effect: The strong turbulence and separation effect of the circulating fluidized bed boiler cyclone separator can promote the full mixing of wastewater droplets and high-temperature flue gas, ensuring complete evaporation of water. At the same time, solid particles are effectively captured to avoid secondary pollution.

[0014] (4) Strong process adaptability: good compatibility with the original desulfurization system, low difficulty in transformation, and easy for industrial application.

[0015] (5) It can achieve “waste treatment with waste”: some components in the desulfurization wastewater (such as calcium components) can be returned to the circulating fluidized bed boiler through the return leg, further participating in the desulfurization reaction in the circulating fluidized bed boiler, further improving the desulfurization efficiency, and achieving “waste treatment with waste”. SUMMARY

[0016] The purpose of the present application is to provide a new method for zero-emission treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator, which adopts a new method for zero-emission treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator composed of a circulating fluidized bed boiler, a circulating fluidized bed boiler cyclone separator, a return material leg, a double-fluid spray gun, a wastewater tank, a wastewater delivery pump A and a wastewater delivery pump B. The present application overcomes the shortcomings of the prior art and proposes a new zero-emission treatment route for desulfurization wastewater using a circulating fluidized bed boiler cyclone separator, which has the characteristics of high synergistic treatment efficiency, simple and reliable system, low investment cost, low energy consumption and cost, stable treatment effect, strong process adaptability and realization of "waste treatment with waste", efficiently realizes low-cost zero-emission treatment of desulfurization wastewater, and greatly improves the reliability and safety of the treatment system.

[0017] To achieve the above purpose, the present application provides a wastewater tank. The desulfurization wastewater generated by the limestone-gypsum wet process is pretreated by a conventional triple tank or an integrated pretreatment device to remove part of the suspended solids and heavy metals, and the high-chlorine and high-salt wastewater formed after treatment is introduced into the wastewater tank. The wastewater tank is made of carbon steel lined with glass flakes, glass fiber reinforced plastic or polyethylene according to the actual needs of the project.

[0018] To achieve the above purpose, the present application provides a wastewater tank. The desulfurization wastewater generated by the limestone-gypsum wet process is pretreated by a conventional triple tank or an integrated pretreatment device to remove part of the suspended solids and heavy metals, and the high-chlorine and high-salt wastewater formed after treatment is introduced into the wastewater tank. The wastewater tank is made of carbon steel lined with glass flakes, glass fiber reinforced plastic or polyethylene according to the actual needs of the project.

[0019] To achieve the above purpose, the present application provides a wastewater tank. The desulfurization wastewater generated by the limestone-gypsum wet process is pretreated by a conventional triple tank or an integrated pretreatment device to remove part of the suspended solids and heavy metals, and the high-chlorine and high-salt wastewater formed after treatment is introduced into the wastewater tank. The wastewater tank is made of carbon steel lined with glass flakes, glass fiber reinforced plastic or polyethylene according to the actual needs of the project.

[0020] In the present invention, tiny droplets atomized by a dual-fluid spray gun enter the circulating fluidized bed boiler cyclone separator along with the high-temperature flue gas. Relying on the high-temperature environment of the flue gas of the circulating fluidized bed boiler (usually 800℃-950℃), the waste heat of the flue gas is used to achieve rapid evaporation of water. At the same time, the salt, heavy metals, calcium components and the like in the wastewater are solidified at high temperature. The solidified particles are mixed into the fly ash, and are efficiently separated and captured by the circulating fluidized bed boiler cyclone separator. They enter the circulating fluidized bed boiler through the return leg, and the evaporated water vapor is mixed into the flue gas and discharged out of the system, thereby achieving zero discharge of desulfurization wastewater.

[0021] In the present invention, due to the strong turbulence and separation effect of the circulating fluidized bed boiler cyclone separator, the wastewater droplets are greatly mixed with the high-temperature flue gas, ensuring the complete evaporation of water. At the same time, solid particles are efficiently separated and captured, avoiding secondary pollution.

[0022] In the present invention, some components in the wastewater (such as calcium components) can be returned to the circulating fluidized bed boiler through the return leg, further participating in the desulfurization reaction in the circulating fluidized bed boiler, further improving the desulfurization efficiency, and realizing "waste treatment with waste".

[0023] On the basis of overcoming the shortcomings of the existing technology, the present invention utilizes the circulating fluidized bed boiler cyclone separator to innovatively propose a new type of zero-emission treatment route for desulfurization wastewater, which has the characteristics of high collaborative treatment efficiency, simple and reliable system, low investment cost, low energy consumption and cost, stable treatment effect, strong process adaptability, and the ability to achieve "waste treatment with waste". It can efficiently achieve low-cost zero-emission treatment of desulfurization wastewater and greatly improve the reliability and safety of the treatment system.

[0024] The core innovation and technical advantages of the patent of this invention are mainly reflected in.

[0025] (1) High efficiency of collaborative treatment: Relying on the high temperature environment (usually 800℃-950℃) of the circulating fluidized bed boiler cyclone separator, the desulfurization wastewater can be directly sprayed into the inlet area of ​​the circulating fluidized bed boiler cyclone separator, and the waste heat of the flue gas can be used to achieve rapid evaporation of water. At the same time, the salt, heavy metals, etc. in the wastewater are solidified at high temperature, eliminating the need for separate evaporation equipment and simplifying the process.

[0026] (2) Low energy consumption and cost: No additional large amount of heat source is required, and the waste heat of boiler flue gas is directly utilized to reduce the energy consumption and equipment investment of traditional evaporation crystallization process, which is suitable for system integration with existing circulating fluidized bed boilers.

[0027] (3) Stable treatment effect: The strong turbulence and separation effect of the cyclone separator can promote the full mixing of wastewater droplets and high-temperature flue gas, ensuring complete evaporation of water. At the same time, solid particles are effectively captured to avoid secondary pollution.

[0028] (4) Strong process adaptability: good compatibility with the original desulfurization system, low difficulty in transformation, and easy for industrial application.

[0029] (5) It can achieve “waste treatment with waste”: some components in the desulfurization wastewater (such as calcium components) can return to the furnace through the return leg, further participate in the desulfurization reaction in the furnace, further improve the desulfurization efficiency, and achieve “waste treatment with waste”.

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention will be described in further detail below with reference to the accompanying drawings.

[0032] Figure 1 It is a schematic diagram of the process flow of the patent of this invention.

[0033] In the figure: 1. Wastewater tank, 2. Wastewater transfer pump A, 3. Wastewater transfer pump B, 4. Circulating fluidized bed boiler, 5. Two-fluid spray gun, 6. Circulating fluidized bed boiler cyclone separator, 7. Return leg. DETAILED DESCRIPTION

[0034] The present invention provides a wastewater tank and arranges wastewater transfer pumps A and B in a one-in-one standby mode. Wastewater transfer pumps A and B are separately connected to the wastewater tank. Multiple dual-fluid spray guns are installed on the flue inlet of a circulating fluidized bed boiler cyclone separator, 2 to 3 meters from the cyclone separator inlet, at equal intervals from top to bottom along the flue cross-section. The number and spacing of the spray guns are designed and determined based on the flue gas volume of the circulating fluidized bed boiler and the cross-sectional area of ​​the cyclone separator inlet flue. The multiple dual-fluid spray guns are separately connected to wastewater transfer pumps A and B.

[0035] When the method of the present invention is in working state, the desulfurization wastewater generated by the limestone-gypsum wet process passes through a conventional triple box or integrated pretreatment to remove some suspended matter and heavy metals, and the high-chloride and salt-containing wastewater formed after treatment enters the wastewater tank.

[0036] When the method of the present invention is in operation, in a one-standby-one-use mode, the wastewater delivery pump A or the wastewater delivery pump B delivers wastewater from the wastewater tank to a plurality of dual-fluid spray guns provided at the inlet flue of the cyclone separator of the circulating fluidized bed boiler.

[0037] When the method of the present invention is in operation, multiple dual-fluid spray guns, connected to wastewater delivery pumps A and B, use compressed air to atomize wastewater into tiny droplets, which are then sprayed at high speed into the circulating fluidized bed boiler cyclone separator. The droplets atomized by the dual-fluid spray guns have a particle size range of 10-90 μm.

[0038] When the method of the present invention is in working state, tiny droplets atomized by the dual-fluid spray gun enter the circulating fluidized bed boiler cyclone separator along with the high-temperature flue gas. Relying on the high-temperature environment of the flue gas of the circulating fluidized bed boiler (usually 800℃-950℃), the waste heat of the flue gas is used to realize rapid evaporation of water. At the same time, the salt, heavy metals, calcium components and the like in the wastewater are solidified at high temperature. The solidified particles are mixed into the fly ash, and are efficiently separated and captured by the circulating fluidized bed boiler cyclone separator. They enter the circulating fluidized bed boiler through the return leg, and the evaporated water vapor is mixed into the flue gas and discharged out of the system, thereby realizing zero emission of desulfurization wastewater.

[0039] When the method of the present invention is in operation, the strong turbulence and separation effect of the circulating fluidized bed boiler cyclone separator greatly promotes the full mixing of wastewater droplets and high-temperature flue gas, ensuring the complete evaporation of water. At the same time, solid particles are efficiently separated and captured, avoiding secondary pollution.

[0040] When the method of the present invention is in working state, the calcium components in the wastewater are returned to the circulating fluidized bed boiler through the return leg, further participating in the desulfurization reaction in the circulating fluidized bed boiler, further improving the desulfurization efficiency and realizing "waste treatment with waste".

[0041] When the method of the present invention is in working state, it has the characteristics of high collaborative processing efficiency, simple and reliable system, low investment cost, low energy consumption and cost, stable treatment effect, strong process adaptability, and the ability to achieve "waste treatment with waste". It can efficiently achieve low-cost zero-emission treatment of desulfurization wastewater and greatly improve the reliability and safety of the treatment system.

[0042] The above is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any changes or modifications made by any technician in this field within the scope of the present invention should be included in the patent scope of the present invention.

Claims

1. A novel method for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator. The method is implemented by a novel system for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator. The novel system for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator comprises a circulating fluidized bed boiler, a circulating fluidized bed boiler cyclone separator, a return leg, a dual-fluid spray gun, a wastewater tank, a wastewater delivery pump A, and a wastewater delivery pump B. The method is characterized by: Wastewater transfer pump A and wastewater transfer pump B are both connected to the wastewater tank through pipelines. Wastewater transfer pump A and wastewater transfer pump B are also connected to multiple dual-fluid spray guns installed at the inlet flue of the circulating fluidized bed boiler cyclone separator through pipelines. The calcium components in the wastewater are returned to the circulating fluidized bed boiler through the return leg. Under operating conditions, relying on the high temperature environment, strong turbulence and separation effect of the flue gas of the circulating fluidized bed boiler, the circulating fluidized bed boiler is used to achieve "waste treatment with waste" and carry out zero-emission treatment of wet desulfurization wastewater. The specific implementation steps are as follows: (1) The desulfurization wastewater generated by the limestone-gypsum wet process passes through a conventional triple box or integrated pretreatment to remove some suspended solids and heavy metals. The high-chloride and salt-containing wastewater formed after treatment enters the wastewater tank; (2) According to the one-standby-one-use mode, the wastewater delivery pump A or the wastewater delivery pump B delivers the wastewater in the wastewater tank to a plurality of dual-fluid spray guns installed at the inlet flue of the cyclone separator of the circulating fluidized bed boiler; (3) Multiple dual-fluid spray guns connected to wastewater delivery pump A and wastewater delivery pump B respectively use compressed air to atomize the wastewater into tiny droplets and then spray them into the circulating fluidized bed boiler cyclone separator at high speed; (4) The tiny droplets atomized by the dual-fluid spray gun enter the circulating fluidized bed boiler cyclone separator along with the high-temperature flue gas. Relying on the high temperature environment of the circulating fluidized bed boiler flue gas (usually 800℃-950℃), the waste heat of the flue gas is used to achieve rapid evaporation of water. At the same time, the salt, heavy metals, calcium components in the wastewater are solidified at high temperature. The solidified particles are mixed with the fly ash and are efficiently separated and captured by the circulating fluidized bed boiler cyclone separator; (5) The calcium components in the wastewater are returned to the circulating fluidized bed boiler through the return leg, further participating in the desulfurization reaction in the circulating fluidized bed boiler, further improving the desulfurization efficiency and achieving "waste treatment with waste"; (6) The water vapor after evaporation of wastewater is mixed with the flue gas and discharged out of the system; (7) Zero emission treatment of wet flue gas desulfurization wastewater is completed.

2. The novel method for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator according to claim 1 is characterized in that: A plurality of dual-fluid spray guns are arranged on the inlet flue of the circulating fluidized bed boiler cyclone separator at a distance of 2 meters to 3 meters from the inlet of the cyclone separator and at equal intervals from top to bottom along the cross section of the flue.

3. The novel method for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator according to claim 1 is characterized in that: The particle size of tiny droplets atomized by the dual-fluid spray gun is in the range of 10-90μm. The tiny droplets enter the circulating fluidized bed boiler cyclone separator with the high-temperature flue gas. Relying on the high temperature environment of the circulating fluidized bed boiler flue gas (usually 800℃-950℃), the waste heat of the flue gas is used to achieve rapid evaporation of water. At the same time, the salt, heavy metals, calcium components in the wastewater are solidified under high temperature. The solidified particles are mixed into the fly ash, and are efficiently separated and captured by the circulating fluidized bed boiler cyclone separator, and enter the circulating fluidized bed boiler through the return leg. The evaporated water vapor is mixed into the flue gas and discharged out of the system, achieving zero discharge of desulfurization wastewater.

4. The novel method for zero-discharge treatment of wet desulfurization wastewater using a circulating fluidized bed boiler cyclone separator according to claim 1 is characterized in that: The calcium components in the wastewater are returned to the circulating fluidized bed boiler through the return leg, further participating in the desulfurization reaction in the circulating fluidized bed boiler, further improving the desulfurization efficiency and achieving "waste treatment with waste".

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