Thermal power plant tail end wastewater evaporative crystallization and solidification system

Abstract

The utility model discloses a thermal power plant tail end wastewater evaporative crystallization curing system which comprises an evaporative concentration decrement unit, a medicament neutralization unit and a drying curing unit, the evaporation concentration decrement unit comprises a first induced draft fan and a concentration tower, and the medicament neutralization unit comprises a modulation box and a solid-liquid separation box; and the drying and curing unit comprises a drying bed and a second induced draft fan. The drying bed comprises a base, an air distribution seat, a vibration fluidization bin, an upper seat and a water distribution pipe.

Description

Technical Field

[0001] The utility model relates to the technical field of environmental protection equipment, in particular to an evaporation, crystallization and solidification system for wastewater at the end of a thermal power plant. Background Art

[0002] The wastewater at the end of the thermal power plant has high salt and chloride ion content, making it difficult to reuse. Taking the applicant as an example, the wastewater at the end of the plant is mainly chemical regeneration wastewater (2.6m 3 / h), fine treatment of recycled wastewater (1.3m 3 / h) and desulfurization wastewater treatment system effluent (11.1m 3 / h), a total of 15m 3 / h. At present, the effluent from the desulfurization wastewater treatment system is treated by a three-tank process. The treated water is sprayed in the coal yard of Unit 7; the chemical regeneration and fine treatment regeneration wastewater is used as floor flushing water for the plant. Due to the high salt and chloride ion content in the terminal wastewater, the use of coal yard spraying will increase the salt and chloride ion content of the coal. Long-term operation may endanger the normal operation of equipment related to the coal transportation system, and a large amount of chloride ions will still return to the boiler system, which will also cause adverse effects. With the further stringent requirements of future environmental protection policies and regulations, the 15m 3 / hThe terminal wastewater must achieve zero discharge.

[0003] At present, zero discharge of high-salt wastewater at the end is generally achieved through concentration reduction and crystallization solidification. Common crystallization solidification processes include evaporation crystallization technology, main flue evaporation technology, etc. Among them, evaporation crystallization (MVR) is suitable for solutions with higher concentrations or materials with higher viscosity, is highly sensitive to materials that are prone to scaling, and has a large footprint and certain environmental risks. Main flue evaporation is suitable for solutions with higher concentrations or materials with higher viscosity, is not suitable for materials that are prone to scaling, and has average processing capacity. Utility Model Content

[0004] The utility model aims to provide a wastewater evaporation, crystallization and solidification system at the end of a thermal power plant to solve the problems existing in the prior art.

[0005] In order to achieve the above-mentioned purpose, the technical solution of the utility model provides a system for evaporation, crystallization and solidification of wastewater at the end of a thermal power plant, comprising an evaporation, concentration and reduction unit, a reagent neutralization unit and a drying and solidification unit; the evaporation, concentration and reduction unit comprises a first induced draft fan and a concentrating tower, and the reagent neutralization unit comprises a modulation box and a solid-liquid separation box; the drying and solidification unit comprises a drying bed and a second induced draft fan; the air inlet end of the first induced draft fan is connected to the flue in front of the desulfurization tower, the air outlet end is connected to the concentrating tower, the air outlet of the concentrating tower is connected to the desulfurization tower, the liquid outlet is connected to the modulation box, the liquid outlet of the modulation box is connected to the solid-liquid separation box, the liquid outlet of the solid-liquid separation box is connected to the drying bed, the air inlet end of the second induced draft fan is connected to the air preheater, the air outlet end is connected to the drying bed, and the air outlet of the drying bed is connected to the electrostatic precipitator.

[0006] Preferably, the drying bed includes a base, an air distribution seat, a vibrating fluidizing bin, an upper seat, and a water distribution pipe; the air distribution seat is arranged at the lower part of the vibrating fluidizing bin and is connected to the second induced draft fan; the vibrating fluidizing bin is a tubular structure, with isolation screens arranged at the upper and lower parts, inert particles arranged inside, and at least one polarization motor arranged on the outside, and the lower part of the vibrating fluidizing bin is connected to the base through a number of springs; the upper seat is arranged at the upper part of the vibrating fluidizing bin, and an air outlet is arranged on the top; the water distribution pipe passes through the upper seat and enters the interior of the upper seat.

[0007] Preferably, the upper portion of the air distribution seat is a truncated cone-shaped cavity which is narrow at the bottom and wide at the top; an ash collecting pipe is provided at the lower portion, and an openable and closable valve is provided at the lower portion of the ash collecting pipe.

[0008] Preferably, the upper seat is also provided with a return air duct, and the air outlet and the electrostatic precipitator connecting duct and the return air duct are provided with valves.

[0009] Preferably, the water distribution pipe is connected to a water distributor, and the water distributor includes a central water pipe, a plurality of annular spray pipes, and radial connecting pipes. The upper part of the central water pipe is connected to the water distribution pipe, and after passing through the isolation screen at the top of the vibrating fluidizing bin, it is connected to a plurality of annular spray pipes through the radial connecting pipes. The lower part of the central water pipe is sealed.

[0010] Preferably, there are two annular spray pipes, which are respectively arranged below the upper isolation screen and in the lower middle part of the vibrating fluidizing bin. The cross-section of the annular spray pipe located below the isolation screen is semi-elliptical or semi-circular, and the cross-section of the annular spray pipe located in the lower middle part of the vibrating fluidizing bin is circular or elliptical.

[0011] Preferably, the vibrating fluidizing bin is provided with an inner wall convex inwardly at the center.

[0012] The utility model provides a flue gas waste heat evaporation drying and solidification technology, which mainly adopts the process route of low-temperature flue gas waste heat concentration and high-temperature hot secondary air drying, can evaporate solutions with high concentrations, has good water quality adaptability, and the system has high reliability and small footprint, and can be installed near the desulfurization tower. Through the connection mode and structural improvement of the drying bed, the crystallized product can be directly introduced into the ESP device for boiler flue gas treatment for treatment, which improves the intensiveness of the system, and the drying efficiency of the equipment can be improved by optimizing and improving the vibration fluidized bin and water distribution structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall solution of the utility model.

[0014] Figure 2 It is a schematic diagram of a drying bed of the utility model.

[0015] Figure 3It is a cutaway schematic diagram of a drying bed of the utility model.

[0016] Figure 4 It is a schematic diagram of a drying bed according to another embodiment of the utility model.

[0017] Figure 5 It is a schematic cross-sectional view of the water distributor area of ​​another embodiment of the utility model.

[0018] Figure 6 It is a schematic cross-sectional view of a vibrating fluidized bed in another embodiment of the utility model. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0020] As attached Figure 1 As shown, a system for evaporating, crystallizing and solidifying wastewater at the end of a thermal power plant according to the utility model comprises an evaporation, concentration and reduction unit 1, a reagent neutralization unit 2 and a drying and solidification unit 3.

[0021] The evaporation concentration reduction unit 1 includes a first induced draft fan 11 and a concentration tower 12 ; the reagent neutralization unit 2 includes a modulation box 21 and a solid-liquid separation box 22 ; and the drying and solidification unit 3 includes a drying bed 31 and a second induced draft fan 32 .

[0022] The high-salt wastewater at the end is sent to the concentration tower 12; the first induced draft fan 11 introduces the low-temperature flue gas (90-130°C) before the desulfurization tower into the concentration tower 12 as a heat source, and the wastewater is concentrated at a high rate of more than 10 times in the concentration spray tower. The evaporated wet flue gas returns to the desulfurization tower, realizing the utilization of clean water; the wastewater is greatly reduced after concentration and enters the modulation box 21 of the reagent neutralization unit 2. The concentrated slurry is weakly acidic and high in chlorine. Hydrated lime is added as a reagent in the modulation box 21 to adjust the pH value of the concentrated slurry to neutral / weakly alkaline. After solid-liquid separation in the solid-liquid separation box 22, some sludge and clear liquid are generated. The main components of the sludge are gypsum, fly ash, etc., which can be mixed with coal for mixed combustion, dehydrated by a plate and frame machine and added to gypsum or transported out. A small amount of clear liquid containing high chloride ions enters the drying bed 31 of the subsequent drying and solidification unit 3.

[0023] The drying and curing unit 3 extracts hot secondary air at about 300° C. from the air preheater of the boiler as a drying medium through the second induced draft fan 32, and enters the drying bed 31 for drying after being pressurized by the hot air fan.

[0024] Among them, the desulfurization tower, air preheater and electrostatic precipitator are existing boiler exhaust treatment devices and are not protected by this application.

[0025] As attached Figure 2 , 3 As shown, the drying bed 31 includes a base 311 , an air distribution seat 312 , a vibrating fluidization bin 313 , an upper seat 314 , and a water distribution pipe 315 .

[0026] The air distribution seat 312 is arranged at the lower part of the vibrating fluidization chamber 313, and the hot air pressurized by the second induced draft fan 32 flows in through the air distribution seat 311. The upper part of the air distribution seat 312 is a truncated cone-shaped cavity that is narrow at the bottom and wide at the top.

[0027] The vibrating fluidizing bin 313 is a tubular structure, with isolation screens 3131 arranged at the upper and lower parts, inert particles arranged inside, and at least one polarization motor 3132 arranged outside, two in the figure. The lower part of the vibrating fluidizing bin 313 is connected to the base 311 through a plurality of springs k.

[0028] The upper seat 314 is disposed on the upper part of the vibrating fluidization bin 313 and is provided with an air outlet 3141 on the upper part. The water distribution pipe 315 passes through the upper seat 314 and enters the interior of the upper seat 314 and is provided with a water outlet on the upper part of the vibrating fluidization bin 313 .

[0029] The water distribution pipe 315 and the air distribution seat 312 are connected to the liquid outlet of the solid-liquid separation box 22 and the air outlet of the second induced draft fan 32 through a hose.

[0030] First, the slurry is sprayed on the surface of the inert particles in the vibrating fluidized bin 313 through the water distribution pipe 315. The polarization motor 3132 is activated while the water is being distributed, which can improve the uniformity of the coating. The inert particles can be conventionally selected in the field. Then, the hot air pressurized by the second induced draft fan 32 enters the drying bed 31. Under the action of wind force and the polarization motor, the inert carrier particles are in a fluidized state and exchange heat and mass with the high-temperature hot air. After the dried slurry is ground by collision between the inert particles, it falls off the surface of the inert carrier and is carried away from the drying bed by the gas. It flows into the electrostatic precipitator (ESP) through the outlet 3141 of the upper seat 314 to capture dust.

[0031] As attached Figure 4As shown, further, the upper seat 314 is also provided with a return air duct 3142, and the air outlet 3141 and the electrostatic precipitator (ESP) connecting pipe and the return air duct 3142 are provided with valves. During the treatment process, the air outlet 3141 and the electrostatic precipitator (ESP) connecting pipe can be closed first to reduce the water vapor entering the electrostatic precipitator (ESP) in the early stage of the treatment, and the return air duct 3142 is opened. The other end of the return air duct 3142 is connected to the lower part of the vibrating fluidization bin 313. After running for a period of time, the return air duct 3142 can be closed again. The valve provided on the return air duct 3142 is provided at the connection point between the return air duct 3142 and the vibrating fluidization bin 313 to prevent inert particles from entering. The return air duct 3142 is arranged at the top of the upper seat 314, and the area connected to the upper seat 314 is provided with an ascending section, and then the pipe is bent downward to be connected to the lower part of the vibrating fluidization bin 313, and the valve is provided on the ascending section.

[0032] Furthermore, a dust collecting pipe 3121 is provided at the lower part of the air distribution seat 312, and an openable and closable valve is provided at the lower part of the dust collecting pipe 3121 for opening and discharging dust when needed.

[0033] As attached Figure 5 As shown, in order to improve the water distribution effect, the water distribution pipe 315 is connected to the water distributor 3151, and the water distributor 3151 includes a central water pipe b1, a plurality of annular spray pipes b2, and a radial connecting pipe b3. The upper part of the central water pipe b1 is connected to the water distribution pipe 315, and after passing through the isolation screen 3131 at the upper part of the vibrating fluidization bin 313, it is connected to the plurality of annular spray pipes b2 through the radial connecting pipe b3. The accompanying drawings include two annular spray pipes b2, which are respectively arranged below the isolation screen 3131 at the upper part and in the middle and lower part of the vibrating fluidization bin 313, and the lower part of the central water pipe b1 is sealed.

[0034] The cross section of the annular spray pipe b2 is circular, elliptical, semi-elliptical, or semi-circular. In the attached figure, the cross section of the annular spray pipe b2 located below the isolation screen 3131 is semi-elliptical or semi-circular, and the cross section of the annular spray pipe b2 located in the middle and lower part of the vibrating fluidized bin 313 is circular or elliptical. The main purpose is to reduce the risk of inert particles breaking after collision with them.

[0035] In order to improve the collision effect of the inert particles, the vibrating fluidized chamber 313 is provided with an inner wall n that bulges inwards, the center of the inner wall bulges inwards, and its cross section is parabolic or arc-shaped, which can increase the probability of mutual collision of the inert particles in the fluidized state. That is, a necking section is provided in the center of the vibrating fluidized chamber 313, and the radius of the area with the smallest inner diameter of the necking section is 50%-80% of the inner diameter of the upper and lower parts of the vibrating fluidized chamber 313.

[0036] It should be noted that, unless otherwise clearly specified and limited, the terms such as "install", "connect", "connect", "fix", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be understood according to specific circumstances.

Claims

1. A system for evaporation, crystallization and solidification of wastewater at the end of a thermal power plant, comprising an evaporation, concentration and reduction unit, a reagent neutralization unit and a drying and solidification unit; the evaporation, concentration and reduction unit comprises a first induced draft fan and a concentration tower, the reagent neutralization unit comprises a modulation box and a solid-liquid separation box; the drying and solidification unit comprises a drying bed and a second induced draft fan; the air inlet end of the first induced draft fan is connected to the flue in front of the desulfurization tower, the air outlet end is connected to the concentration tower, the air outlet of the concentration tower is connected to the desulfurization tower, the liquid outlet is connected to the modulation box, the liquid outlet of the modulation box is connected to the solid-liquid separation box, the liquid outlet of the solid-liquid separation box is connected to the drying bed, the air inlet end of the second induced draft fan is connected to the air preheater, the air outlet end is connected to the drying bed, and the air outlet of the drying bed is connected to the electrostatic precipitator, characterized in that The drying bed includes a base, an air distribution seat, a vibrating fluidizing bin, an upper seat, and a water distribution pipe; the air distribution seat is arranged at the lower part of the vibrating fluidizing bin and is connected to the second induced draft fan; the vibrating fluidizing bin is a tubular structure, with isolation screens arranged at the upper and lower parts, inert particles arranged inside, and at least one polarization motor arranged outside, and the lower part of the vibrating fluidizing bin is connected to the base through a number of springs; the upper seat is arranged at the upper part of the vibrating fluidizing bin, and an air outlet is arranged on the top; the water distribution pipe passes through the upper seat and enters the interior of the upper seat; the vibrating fluidizing bin is provided with an inner wall with a central inward protrusion.

2. According to claim 1, a thermal power plant terminal wastewater evaporation crystallization solidification system is characterized in that: The upper part of the air distribution seat is a truncated cone-shaped cavity which is narrow at the bottom and wide at the top; the lower part is provided with an ash collecting pipe, and the lower part of the ash collecting pipe is provided with an openable and closable valve.

3. According to claim 1, a thermal power plant terminal wastewater evaporation crystallization solidification system is characterized in that: The upper seat is also provided with a return air duct, and a valve is provided on the air outlet and the electrostatic precipitator connecting duct and the return air duct.

4. According to claim 1, a thermal power plant terminal wastewater evaporation crystallization solidification system is characterized in that: The water distribution pipe is connected to the water distributor, and the water distributor includes a central water pipe, a plurality of annular spray pipes, and radial connecting pipes. The upper part of the central water pipe is connected to the water distribution pipe, and after passing through the isolation screen at the top of the vibrating fluidizing bin, it is connected to the plurality of annular spray pipes through the radial connecting pipes. The lower part of the central water pipe is sealed.

5. A thermal power plant terminal wastewater evaporation crystallization solidification system according to claim 4, characterized in that: There are two annular spray pipes, which are respectively arranged below the upper isolation screen and in the lower middle part of the vibrating fluidizing bin. The cross-section of the annular spray pipe located below the isolation screen is semi-elliptical or semi-circular, and the cross-section of the annular spray pipe located in the lower middle part of the vibrating fluidizing bin is circular or elliptical.

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