An integrated desulfurization wastewater concentration and drying tower system

Abstract

The invention discloses an integrated desulfurization wastewater concentration and drying tower system, comprising a desulfurization wastewater concentration and drying integrated tower, a boiler flue gas inlet pipe, an air preheater, a flue gas distributor, an electrostatic precipitator, an outlet flue, a desulfurization wastewater pipe, a desulfurization wastewater pretreatment water tank, an ash conveying pipe and a desulfurization wastewater concentrated liquid buffer tank; the desulfurization wastewater concentration and drying integrated tower is provided with a tower top demister, a desulfurization wastewater concentration spray layer, a pre-concentration cooling chamber and a central tube from top to bottom, wherein the central tube is provided with a flue gas distributor, a circular rising chamber is formed between the central tube and the inner wall of the desulfurization wastewater concentration and drying integrated tower, and the circular rising chamber is connected with the pre-concentration cooling chamber; the central tube is provided with a desulfurization wastewater concentration nozzle and a desulfurization wastewater concentrated liquid atomizing nozzle from top to bottom, and the system has a simple structure, low investment cost and good economy.

Description

Technical Field

[0001] The invention belongs to the technical field of pollutant control and relates to an integrated desulfurization wastewater concentration and drying tower system. Background Art

[0002] SO2 is one of the most important pollutants in my country's air pollutants and the main cause of acid rain. The SO2 emitted from flue gas from coal-fired power plants is the main source of pollutants in the atmosphere. The ultra-low emission standard for flue gas from thermal power plants has put forward higher requirements for coal-fired power plants, which is equivalent to further improving the requirements for the stability and reliability of the operation of flue gas desulfurization systems in power plants.

[0003] At present, more than 90% of flue gas desulfurization in coal-fired power plants adopts limestone-gypsum wet desulfurization process, and the wastewater of coal-fired power plants mainly comes from desulfurization absorption towers. The wastewater of desulfurization absorption towers is composed of wastewater generated by boiler feed water treatment system, high salt water generated by circulating water system and cooling water system, wastewater generated by desulfurization system itself and other system wastewater. Therefore, the wastewater of desulfurization system collects most of the wastewater of thermal power plants and is the terminal wastewater of coal-fired power plants, with the worst water quality. In order to maintain the quality of the slurry system of the desulfurization system, ensure the stable operation of the desulfurization system and the quality of gypsum, a certain amount of wastewater must be discharged from the desulfurization system. These discharged desulfurization wastewaters often contain many impurities, such as sulfates, heavy metals, suspended solids, and heavy metals such as Pb, Cd, Cr, Ni, Hg, etc., which are listed as the first category of pollutants in the "Comprehensive Sewage Discharge Standard". The discharged wastewater must meet the standards and be discharged with a license. Moreover, the heavy metal ions contained in desulfurization wastewater are quite toxic. It is difficult for them to be self-purified or biodegraded when discharged into the natural environment. They will be enriched in natural water bodies and cause harm to organisms in the water bodies when reaching a certain amount.

[0004] For the zero-discharge process of desulfurization wastewater, the current coal-fired power plants usually use the wastewater concentration reduction + evaporation drying route. Among the processes that have been implemented for zero-discharge of wastewater, the one that can achieve relatively stable operation is wastewater thermal concentration + evaporation drying, but there are problems such as extracting the flue gas from the inlet of the air preheater and the inlet of the desulfurization system separately, which makes the flue gas system complicated, the construction of the thermal concentration tower and the evaporation drying tower requires a large area and equipment investment, and the large amount of flue gas extracted from the inlet of the air preheater affects the overall economic efficiency of the unit. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned shortcomings of the prior art and provide an integrated desulfurization wastewater concentration and drying tower system, which has a simple structure, low investment cost and good economy.

[0006] To achieve the above-mentioned purpose, the integrated desulfurization wastewater concentration and drying tower system of the present invention comprises a desulfurization wastewater concentration and drying integrated tower, a boiler flue gas inlet pipe, an air preheater, a flue gas distributor, an electrostatic precipitator, an outlet flue, a desulfurization wastewater pipeline, a desulfurization wastewater pretreatment water tank, an ash conveying pipeline and a desulfurization wastewater concentrate buffer tank;

[0007] The desulfurization wastewater concentration and drying integrated tower is provided with a tower top demister, a desulfurization wastewater concentration spray layer, a pre-concentration cooling chamber and a central tube from top to bottom, wherein a flue gas distributor is provided in the central tube, and a circular rising chamber is formed between the central tube and the inner wall of the desulfurization wastewater concentration and drying integrated tower, and the circular rising chamber is connected to the pre-concentration cooling chamber; the desulfurization wastewater concentration nozzle and the desulfurization wastewater concentrated liquid atomizing nozzle are provided in the central tube from top to bottom;

[0008] The outlet of the boiler flue gas inlet pipe is divided into two routes, one of which is connected to the inlet of the air preheater, and the other is connected to the flue gas inlet of the flue gas distributor. The outlet of the air preheater is connected to the inlet of the electrostatic precipitator. The outlet of the electrostatic precipitator is divided into two routes, one of which is connected to the outlet flue, and the other is connected to the flue gas inlet of the flue gas distributor. The top outlet of the desulfurization wastewater concentration and drying integrated tower is divided into two routes, one of which is connected to the outlet flue, and the other is connected to the inlet of the electrostatic precipitator;

[0009] The desulfurization wastewater pipeline is connected to the inlet of the desulfurization wastewater pretreatment water tank, and the outlet of the desulfurization wastewater pretreatment water tank is connected to the inlet of the desulfurization wastewater concentration spray layer;

[0010] A dry crystal ash hopper and a desulfurization wastewater concentrated liquid hopper are arranged at the bottom of the desulfurization wastewater concentrating and drying integrated tower, wherein the dry crystal ash hopper is connected to the ash conveying pipeline, the desulfurization wastewater concentrated liquid hopper is connected to the desulfurization wastewater concentrated liquid buffer tank, and the outlet of the desulfurization wastewater concentrated liquid buffer tank is connected to the desulfurization wastewater concentrated liquid atomizing nozzle and the desulfurization wastewater concentrating nozzle.

[0011] The annular rising chamber is connected with the pre-concentration cooling chamber through an oblique Z-shaped channel.

[0012] An electric shut-off door is installed on the inlet cone section of the dry crystal ash hopper, and the electric shut-off door is connected to the air compressor tank.

[0013] The outlet of the boiler flue gas inlet pipe is connected to the flue gas inlet of the flue gas distributor via a hot flue gas regulating valve.

[0014] The outlet of the electrostatic precipitator is connected to the flue gas inlet of the flue gas distributor through a low-temperature flue gas regulating valve and an exhaust blower.

[0015] The top outlet of the desulfurization wastewater concentration and drying integrated tower is divided into two routes, one of which is connected to the outlet flue through the concentrated flue gas discharge baffle, and the other is connected to the inlet of the electrostatic precipitator through the drying crystallization flue gas discharge baffle;

[0016] The outlet of the desulfurization wastewater pretreatment water tank is connected to the inlet of the desulfurization wastewater concentration spray layer through the clarified desulfurization wastewater delivery pump, the desulfurization wastewater buffer tank, the desulfurization wastewater concentration delivery pump in sequence;

[0017] The outlet of the desulfurization wastewater concentrate buffer tank is divided into two paths after passing through the desulfurization wastewater concentrate delivery pump, one of which is connected to the desulfurization wastewater concentrate atomizing nozzle through the wastewater concentration regulating valve, and the other is connected to the desulfurization wastewater concentration nozzle through the wastewater drying regulating valve.

[0018] An induced draft fan is provided on the outlet flue.

[0019] The present invention has the following beneficial effects:

[0020] The integrated desulfurization wastewater concentration and drying tower system of the present invention adopts an integrated design in specific operation, wherein the desulfurization wastewater concentration and drying integrated tower is provided with a tower top demister, a desulfurization wastewater concentration spray layer, a pre-concentration cooling chamber and a central tube from top to bottom, wherein a flue gas distributor is provided in the central tube, and a circular rising chamber is formed between the central tube and the inside of the desulfurization wastewater concentration and drying integrated tower, and the circular rising chamber is connected to the pre-concentration cooling chamber; the desulfurization wastewater concentration nozzle and the desulfurization wastewater concentrated liquid atomization nozzle are provided in the central tube from top to bottom, and the desulfurization wastewater concentration and drying integrated tower is used to realize the wastewater thermal concentration and evaporation drying process, which has a small equipment footprint compared with the existing process, saves construction investment, has good economic efficiency, and has a simple structure, which improves the stability of the operation of the desulfurization wastewater zero discharge system. It should be noted that the pre-concentration cooling chamber uses the flue gas with a higher temperature after drying and crystallization to further pre-concentrate the desulfurization wastewater, reduce the energy consumption of the desulfurization wastewater zero discharge system, and protect the safe operation of equipment such as the demister. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of the present invention.

[0022] Among them, 1 is an air preheater, 2 is an electrostatic precipitator, 3 is an induced draft fan, 4 is a hot flue gas regulating valve, 5 is a low-temperature flue gas regulating valve, 6 is an exhaust blower, 7 is an air compressor tank, 8 is a drying tower ash delivery valve, 9 is a concentrated liquid delivery valve, 10 is an electric shut-off door, 11 is a desulfurization wastewater concentration and drying integrated tower, 12 is a circular riser, 13 is a desulfurization wastewater concentrated liquid atomizing nozzle, 14 is a desulfurization wastewater concentration nozzle, 15 is a flue gas distributor, 16 is a pre-concentration Cooling chamber, 17 is the desulfurization wastewater concentration spray layer, 18 is the tower top demister, 19 is the drying crystallization flue gas emission baffle, 20 is the concentrated flue gas emission baffle, 21 is the wastewater concentration regulating valve, 22 is the wastewater drying regulating valve, 23 is the desulfurization wastewater concentrate buffer tank, 24 is the desulfurization wastewater concentrate delivery pump, 25 is the desulfurization wastewater concentration delivery pump, 26 is the desulfurization wastewater buffer tank, 27 is the clarified desulfurization wastewater delivery pump, and 28 is the desulfurization wastewater pretreatment water tank. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0024] refer to Figure 1The integrated desulfurization wastewater concentration and drying tower system of the present invention comprises a desulfurization wastewater concentration and drying integrated tower 11, a boiler flue gas inlet pipe, an air preheater 1, a flue gas distributor 15, an electrostatic precipitator 2, an outlet flue, a desulfurization wastewater pipeline, a desulfurization wastewater pretreatment water tank 28, an ash conveying pipeline and a desulfurization wastewater concentrate buffer tank 23; the desulfurization wastewater concentration and drying integrated tower 11 is provided with a tower top demister 18, a desulfurization wastewater concentration spray layer 17, a pre-concentration desulfurization tank 28, a pre-concentration desulfurization tank 29 ... Greenhouse 16 and central tube, wherein a flue gas distributor 15 is arranged in the central tube, a circular rising chamber 12 is formed between the central tube and the inner wall of the desulfurization wastewater concentration and drying integrated tower 11, and the circular rising chamber 12 is connected to the pre-concentration and cooling chamber 16; desulfurization wastewater concentration nozzles 14 and desulfurization wastewater concentrate atomization nozzles 13 are arranged in sequence from top to bottom in the central tube; the outlet of the boiler flue gas inlet pipe is divided into two paths, one of which is connected to the inlet of the air preheater 1, and the other is connected to the flue gas inlet of the flue gas distributor 15, the outlet of the air preheater 1 is connected to the inlet of the electrostatic precipitator 2, the outlet of the electrostatic precipitator 2 is divided into two paths, one of which is connected to the outlet flue, and the other is connected to the flue gas inlet of the flue gas distributor 15, the top outlet of the desulfurization wastewater concentration and drying integrated tower 11 is divided into two paths, one of which is connected to the outlet flue, and the other is connected to the inlet of the electrostatic precipitator 2; the desulfurization wastewater pipeline is connected to the inlet of the desulfurization wastewater pretreatment water tank 28 The outlet of the desulfurization wastewater pretreatment water tank 28 is connected with the inlet of the desulfurization wastewater concentration spray layer 17; a dry crystal ash hopper and a desulfurization wastewater concentrated liquid hopper are arranged at the bottom of the desulfurization wastewater concentration and drying integrated tower 11, wherein the dry crystal ash hopper is connected with the ash conveying pipeline, the desulfurization wastewater concentrated liquid hopper is connected with the desulfurization wastewater concentrated liquid buffer tank 23, and the outlet of the desulfurization wastewater concentrated liquid buffer tank 23 is connected with the desulfurization wastewater concentrated liquid atomizing nozzle 13 and the desulfurization wastewater concentrating nozzle 14.

[0025] The annular rising chamber 12 is connected to the pre-concentration and lowering chamber 16 through an oblique Z-shaped passage.

[0026] An electric shut-off door 10 is installed on the inlet cone section of the dry crystal ash hopper, and the electric shut-off door 10 is connected to the air compressor tank 7.

[0027] The outlet of the boiler flue gas inlet pipe is connected to the flue gas inlet of the flue gas distributor 15 via the hot flue gas regulating valve 4 .

[0028] The outlet of the electrostatic precipitator 2 is connected to the flue gas inlet of the flue gas distributor 15 through the low-temperature flue gas regulating valve 5 and the exhaust blower 6.

[0029] The top outlet of the desulfurization wastewater concentration and drying integrated tower 11 is divided into two routes, one of which is connected to the outlet flue through the concentrated flue gas discharge baffle 20, and the other is connected to the inlet of the electrostatic precipitator 2 through the drying crystallization flue gas discharge baffle 19;

[0030] The outlet of the desulfurization wastewater pretreatment water tank 28 is connected to the inlet of the desulfurization wastewater concentration spray layer 17 through the clarified desulfurization wastewater delivery pump 27, the desulfurization wastewater buffer tank 26, and the desulfurization wastewater concentration delivery pump 25 in sequence;

[0031] The outlet of the desulfurization wastewater concentrate buffer tank 23 is divided into two paths after passing through the desulfurization wastewater concentrate delivery pump 24, one of which is connected to the desulfurization wastewater concentrate atomizing nozzle 13 through the wastewater concentration regulating valve 21, and the other is connected to the desulfurization wastewater concentration nozzle 14 through the wastewater drying regulating valve 22.

[0032] An induced draft fan 3 is provided on the outlet flue.

[0033] The specific implementation process of the present invention is:

[0034] In the desulfurization wastewater concentration stage, the exhaust blower 6 extracts the flue gas from the outlet of the electrostatic precipitator 2 and sends it to the flue gas distributor 15. After being distributed by the flue gas distributor 15, the low-temperature flue gas flows downward along the central tube together with the desulfurization wastewater concentrate atomized by the desulfurization wastewater concentration nozzle 14. During the flow process, part of the water evaporated from the desulfurization wastewater concentrate is concentrated, so that the flue gas temperature is reduced. After the flue gas temperature is reduced, it rises through the annular rising chamber 12 outside the central tube together with the evaporated water of the desulfurization wastewater. Then, the desulfurized wastewater enters the pre-concentration cooling chamber 16 through the oblique Z-shaped channel, and finally the desulfurized wastewater from the desulfurized wastewater buffer tank 26 is further cooled by the desulfurized wastewater concentration spray layer 17, and then is defogged by the tower top demister 18 and discharged into the outlet flue. The concentrated desulfurized wastewater enters the desulfurized wastewater concentrated liquid hopper, and then is sent to the desulfurized wastewater concentrated liquid buffer tank 23 through the concentrated liquid delivery valve 9, and the desulfurized wastewater concentrated liquid is further concentrated; the desulfurized wastewater enters the desulfurized wastewater pre-concentration cooling chamber 16, and finally, the desulfurized wastewater ... concentrated by the desulfurized wastewater concentration spray layer 17, and then the desulfurized wastewater is further concentrated by the desulfurized wastewater concentration spray layer 17. The large suspended solids in the desulfurization wastewater are initially precipitated in the treatment water tank 28, and the precipitated sludge is discharged into the gypsum dehydration system for treatment. The desulfurization wastewater after initial precipitation is pumped into the desulfurization wastewater buffer tank 26 by the clarified desulfurization wastewater delivery pump 27, and then sent to the desulfurization wastewater concentration spray layer 17 by the desulfurization wastewater concentration delivery pump 25. The flow rate of the wastewater in the desulfurization wastewater concentration spray layer 17 is adjusted according to the flue gas temperature to control the pre-concentration ratio. The pre-concentrated wastewater enters the desulfurization wastewater concentration In the liquid buffer tank 23, the concentrated desulfurized wastewater in the desulfurized wastewater concentrated liquid buffer tank 23 is pumped into the desulfurized wastewater concentration nozzle 14 for atomization through the desulfurized wastewater concentrated liquid delivery pump 24, and then concentrated with the flue gas evaporated water evenly distributed by the flue gas distributor 15. The concentrated wastewater flow rate and concentration ratio are adjusted according to the extracted flue gas temperature and flue gas volume. The concentrated desulfurized wastewater falls into the desulfurized wastewater concentrated liquid buffer tank 23 and finally enters the cycle until the desulfurized wastewater is concentrated to the set ratio.

[0035] In the stage of evaporation and crystallization of desulfurized wastewater, the hot flue gas regulating valve 4 is used to adjust the hot flue gas volume of the flue gas with higher inlet temperature of the air preheater 1. In the hot flue gas distributor 15, the hot flue gas is distributed by the flue gas distributor 15 and flows downward along the central tube together with the concentrated desulfurized wastewater atomized by the desulfurized wastewater concentrate atomizing nozzle 13. During the flow, the concentrated desulfurized wastewater is evaporated by the flue gas to become gray flue gas, which is also reduced. The flue gas with higher temperature and the evaporated water in the desulfurized wastewater concentrate rise together through the annular rising chamber 12 outside the central tube, and enter the pre-concentration cooling chamber 1 through the oblique Z-shaped channel at the upper part of the annular rising chamber 12. 6. The flue gas with higher temperature contacts with the clarified desulfurized wastewater from the desulfurized wastewater buffer tank 26 which has been atomized by the desulfurized wastewater concentration spray layer 17 to further cool down, and then is discharged after the mist droplets in the flue gas are removed by the tower top demister 18, and then is discharged into the electrostatic precipitator 2 through the drying and crystallization flue gas discharge baffle 19. The wastewater flow in the desulfurized wastewater concentration spray layer 17 is adjusted according to the flue gas temperature to control the pre-concentration ratio, and the desulfurized wastewater pre-concentrated at the top enters the desulfurized wastewater concentrated liquid buffer tank 23; the ash after the desulfurized wastewater concentrate is evaporated and crystallized falls into the crystallization ash hopper controlled by the electric shut-off door 10, and is finally sent to the ash storage through the drying tower ash conveying valve 8.

[0036] According to the characteristic of intermittent operation of desulfurization wastewater discharge, the present invention combines a wastewater concentration tower and a drying crystallization tower into one. The integrated desulfurization wastewater concentration and drying tower respectively operates alternately as a desulfurization wastewater concentration tower and a concentrated liquid drying tower. When the wastewater is concentrated, the heat source entering the integrated desulfurization wastewater concentration and drying tower uses the flue gas with a relatively low outlet temperature of an electrostatic precipitator 2. When the concentrated liquid is dried, the heat source entering the integrated desulfurization wastewater concentration and drying tower uses the hot flue gas at the inlet of an air preheater 1. The desulfurization wastewater concentration tower and the wastewater concentrated liquid drying tower are combined into one, which saves equipment floor space and reduces construction investment.

Claims

1. An integrated desulfurization wastewater concentration and drying tower system, characterized in that: It comprises a desulfurization wastewater concentration and drying integrated tower (11), a boiler flue gas inlet pipe, an air preheater (1), a flue gas distributor (15), an electrostatic precipitator (2), an outlet flue, a desulfurization wastewater pipe, a desulfurization wastewater pretreatment water tank (28), an ash conveying pipe and a desulfurization wastewater concentrate buffer tank (23); A desulfurized wastewater concentration and drying integrated tower (11) is provided with a tower top demister (18), a desulfurized wastewater concentration spray layer (17), a pre-concentration cooling chamber (16) and a central tube from top to bottom, wherein a flue gas distributor (15) is provided in the central tube, and a circular rising chamber (12) is formed between the central tube and the inner wall of the desulfurized wastewater concentration and drying integrated tower (11), and the circular rising chamber (12) is connected to the pre-concentration cooling chamber (16); a desulfurized wastewater concentration nozzle (14) and a desulfurized wastewater concentrate atomizing nozzle (13) are provided in the central tube from top to bottom; The outlet of the boiler flue gas inlet pipe is divided into two paths, one of which is connected to the inlet of the air preheater (1), and the other is connected to the flue gas inlet of the flue gas distributor (15); the outlet of the air preheater (1) is connected to the inlet of the electrostatic precipitator (2); the outlet of the electrostatic precipitator (2) is divided into two paths, one of which is connected to the outlet flue, and the other is connected to the flue gas inlet of the flue gas distributor (15); the top outlet of the desulfurization wastewater concentration and drying integrated tower (11) is divided into two paths, one of which is connected to the outlet flue, and the other is connected to the inlet of the electrostatic precipitator (2); The desulfurization wastewater pipeline is connected to the inlet of the desulfurization wastewater pretreatment water tank (28), and the outlet of the desulfurization wastewater pretreatment water tank (28) is connected to the inlet of the desulfurization wastewater concentration spray layer (17); A drying crystal ash hopper and a desulfurized wastewater concentrated liquid hopper are provided at the bottom of the desulfurized wastewater concentrated drying tower (11), wherein the drying crystal ash hopper is connected to the ash conveying pipeline, the desulfurized wastewater concentrated liquid hopper is connected to the desulfurized wastewater concentrated liquid buffer tank (23), and the outlet of the desulfurized wastewater concentrated liquid buffer tank (23) is connected to the desulfurized wastewater concentrated liquid atomizing nozzle (13) and the desulfurized wastewater concentrated liquid nozzle (14); The annular ascending chamber (12) is connected to the pre-concentration and lowering chamber (16) through an oblique Z-shaped channel; An electric shutoff door (10) is installed on the inlet cone section of the dry crystal ash hopper, and the electric shutoff door (10) is connected to the air compressor tank (7).

2. The integrated desulfurization wastewater concentration and drying tower system according to claim 1 is characterized in that: The outlet of the boiler flue gas inlet pipe is connected to the flue gas inlet of the flue gas distributor (15) via a hot flue gas regulating valve (4).

3. The integrated desulfurization wastewater concentration and drying tower system according to claim 1 is characterized in that: The outlet of the electrostatic precipitator (2) is connected to the flue gas inlet of the flue gas distributor (15) via a low-temperature flue gas regulating valve (5) and an exhaust blower (6).

4. The integrated desulfurization wastewater concentration and drying tower system according to claim 1 is characterized in that: The top outlet of the desulfurized wastewater concentration and drying integrated tower (11) is divided into two paths, one of which is connected to the outlet flue through a concentrated flue gas discharge baffle (20), and the other is connected to the inlet of the electrostatic precipitator (2) through a dried crystallized flue gas discharge baffle (19).

5. The integrated desulfurization wastewater concentration and drying tower system according to claim 1 is characterized in that: The outlet of the desulfurization wastewater pretreatment water tank (28) is connected to the inlet of the desulfurization wastewater concentration spray layer (17) via the clarified desulfurization wastewater delivery pump (27), the desulfurization wastewater buffer tank (26), and the desulfurization wastewater concentration delivery pump (25) in sequence.

6. The integrated desulfurization wastewater concentration and drying tower system according to claim 1 is characterized in that: The outlet of the desulfurized wastewater concentrate buffer tank (23) is divided into two paths after passing through the desulfurized wastewater concentrate delivery pump (24), one of which is connected to the desulfurized wastewater concentrate atomizing nozzle (13) through the wastewater concentration regulating valve (21), and the other is connected to the desulfurized wastewater concentration nozzle (14) through the wastewater drying regulating valve (22).

7. The integrated desulfurization wastewater concentration and drying tower system according to claim 1 is characterized in that: An induced draft fan (3) is provided on the outlet flue.

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