CN104150552A - Distillation drying tower for treating desulfurized waste water in thermal power plant - Google Patents

Abstract

The invention relates to an evaporation and drying tower for treating desulfurization wastewater in a thermal power plant. An imaginary circle is circumscribed in the cylinder body of the drying tower. The center of the imaginary circle is located on the center line of the cylinder body of the evaporation tower. The inner wall of the cylinder body of the evaporation tower is located above the entrance flue. There is a circle of air nozzles, the outlet centerlines of the multiple atomizing nozzles in the circle of atomizing nozzles are circumscribed in an imaginary circle, and the outlet centerlines of the multiple air nozzles in the circle of air nozzles point to the imaginary circle obliquely. The device can effectively treat wastewater with high salt content, has a simple structure, can increase the humidity of the flue gas at the inlet of the electrostatic precipitator, improve the efficiency of the electrostatic precipitator, realize zero discharge of wastewater in the true sense, and reduce air pollution caused by dust particles.

Description

An evaporation and drying tower for treating desulfurization wastewater in thermal power plants

technical field

The invention relates to the field of waste water treatment, in particular to the field of desulfurization waste water from thermal power plants and the field of waste water with high salinity that is difficult to treat in other industries, and in particular to an evaporation tower for treating desulfurization waste water from thermal power plants.

Background technique

The shortage of water resources and the environmental pollution of discharged wastewater have become a worldwide problem. Thermal power plants, as large water users, are very important to save water and reduce discharged wastewater in terms of economy and environmental protection. Therefore, the research and development of devices suitable for the production of thermal power plants and domestic sewage treatment and reuse, reducing the investment and operating costs of sewage treatment, and achieving the goal of zero discharge of wastewater have very important practical significance for my country's national economic and social development and environmental protection.

At present, 90% or more of the country's thermal power generation units use wet desulfurization technology, as well as desulfurization treatment in the iron and steel industry, resulting in a large amount of desulfurization wastewater. The wet desulfurization wastewater is high-concentration suspended solids, high chloride, high-salt, high-concentration heavy metal wastewater, which is extremely polluting to the environment and difficult to treat. It is also the biggest difficulty for power plants to achieve zero discharge of wastewater. Domestic treatment of desulfurization wastewater is mainly to give priority to reuse after treatment, and if there is no condition for reuse, it will be discharged after treatment to meet the standard. Since the desulfurization wastewater is still high-chloride, high-salt and contains trace heavy metal wastewater after preliminary treatment, its reuse range is very limited.

At present, traditional chemical treatment methods of neutralization, precipitation, flocculation, concentration and clarification are often used for desulfurization wastewater in thermal power plants. However, the cost of chemical treatment is high, and chemicals need to be added continuously, which is labor-intensive and cannot be recycled. Another chemical treatment method is required. Chloride ions in the wastewater cannot be removed. If the waste liquid evaporation tower is used to treat desulfurization wastewater, the above problems do not exist.

Contents of the invention

Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide a low-cost, simple structure and increase the humidity of the flue gas at the inlet of the electrostatic precipitator, which can realize the true zero discharge of desulfurization wastewater in thermal power plants. Desulfurization of thermal power plants The waste water is evaporated to dryness tower.

In order to achieve the above object, the present invention adopts the following technical scheme: an evaporation tower for treating desulfurization wastewater in a thermal power plant, comprising an evaporation tower cylinder body, the top of the evaporation tower cylinder body has a flue gas outlet, and the flue gas outlet shown in The upper part is connected with an outlet flue, and the bottom of the outlet flue is located on the upper part of the evaporation tower body, and the bottom of the outlet flue is provided with a mechanical filter;

The bottom of the cylinder body of the evaporation tower is provided with a scraper slag remover for discharging the large particles deposited at the bottom of the tower;

The cylinder body of the evaporation tower has a flue gas inlet, and the flue gas inlet shown is connected with an inlet flue. The center line of the inlet flue is circumscribed with an imaginary circle in the cylinder body of the evaporation tower, and the center of the imaginary circle Located on the centerline of the evaporation tower cylinder, its radius is 0.2-0.8 times the radius of the evaporation tower cylinder, and the imaginary circle is set horizontally;

The inner wall of the evaporation tower cylinder body is provided with at least one circle of atomizing nozzles along the height direction, and each circle of atomization nozzles includes a plurality of atomization nozzles, and the plurality of atomization nozzles in each circle of atomization nozzles are arranged along the evaporation tower cylinder body. The inner wall of the inner wall is arranged circumferentially, and the circle of atomizing nozzles closest to the bottom of the evaporation tower is located above the inlet flue, and the outlet centerlines of the multiple atomizing nozzles in the circle of atomizing nozzles are circumscribed on the imaginary round;

The inner wall of the evaporation tower cylinder is also provided with a circle of air nozzles in the circumferential direction. The circle of air nozzles is located below the inlet flue and includes a plurality of air nozzles. The outlet centerlines of the plurality of air nozzles point to the The boundary line of the imaginary circle .

As an optimization, the rotation direction of the fine liquid droplets sprayed from the atomizing nozzle is opposite to the rotation direction of the flue gas sprayed from the inlet flue.

As an optimization, the inner wall of the evaporation tower cylinder is provided with multiple rings of atomizing nozzles along the height direction, and the distance between two adjacent rings of atomizing nozzles is equal.

As an optimization, the distance between two adjacent atomizing nozzles in each circle of atomizing nozzles is equal.

The present invention is used as the pre-flue gas treatment technology of the desulfurization tower, where the hot flue gas is humidified and cooled, which can replace the water spray cooling treatment at the entrance of the desulfurization absorption tower, and increase the humidity of the flue gas, which is conducive to improving the dust removal effect of the electrostatic precipitator. Compared with the prior art, the present invention also has the following advantages:

1. The present invention utilizes a flue with a height difference between the outlet of the air preheater of the thermal power plant and the inlet of the electrostatic precipitator, and the evaporation tower device is arranged in the middle, and the heat of the flue gas entering the waste water evaporation tower and the introduction of high-temperature air are used to desulfurize The waste water is treated by atomization and evaporation. The micron-sized fine solid particles, various ions and heavy metal elements in the waste water are dried and crystallized and mixed with dust in the flue gas. The large particles settle at the bottom of the tower and are discharged by the bottom scraper slag remover. Small particles enter the electrostatic precipitator with the flue gas and are captured by the electrodes, and are discharged together with the ash, and the waste water steam is discharged with the flue gas, which not only can realize the true zero discharge of desulfurization waste water, but also reduce the emission of dust particles in thermal power plants, which is in line with the reality of environmental protection requirements, and can save processing costs.

2. The desulfurization wastewater evaporation and drying tower provided by the present invention can conveniently solve the current desulfurization wastewater treatment problems, and the process method is simple, and the investment and operation costs are low. After being put into market operation, it can replace various existing desulfurization wastewater treatment equipment in thermal power plants use. It will greatly reduce the cost of desulfurization wastewater treatment and equipment maintenance costs, and it will be popularized and used in desulfurization wastewater such as coal-fired thermal power generation units, with a huge market prospect.

3. Utilizing the heat of flue gas and hot air and the atomization effect of the atomizing nozzle can accelerate the rapid evaporation of waste water, and ensure that the temperature of the flue gas in the waste water evaporation tower is always kept above the acid dew point temperature of the flue gas, and can improve the efficiency of the flue gas. The humidity of the gas entering the electrostatic precipitator improves the dust removal effect of the electrostatic precipitator.

Description of drawings

Fig. 1 is a schematic structural view of an evaporation tower for treating desulfurization wastewater from a thermal power plant in Example 1.

Fig. 2 is a cross-sectional view at Fig. 1A-A.

Fig. 3 is a cross-sectional view at Fig. 1B-B.

Fig. 4 is a schematic structural view of the desulfurization wastewater evaporation tower structure in Example 2.

In the attached drawings: 1—Exit flue; 2—Mechanical filter; 3—Evaporation tower cylinder; 4—Atomizing nozzle;

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment 1: Treatment of thermal power plant desulfurization wastewater evaporation tower, as shown in Figure 1, including outlet flue 1, mechanical filter 2, evaporation tower cylinder 3, atomizing nozzle 4, tuyere 5, scraper slag removal Machine 6, inlet flue 7, the waste water evaporation tower utilizes the effect of the evaporation tower, and desulfurization wastewater or other waste water with high salt content that is difficult to recycle is first atomized through the atomizing nozzle, and then evaporated in the evaporation tower Curing treatment.

There is a flue gas outlet on the top of the evaporation tower body 3, the flue gas outlet shown is connected with an outlet flue 1, the bottom of the outlet flue 1 is located at the upper part of the evaporation tower body 3, and the bottom of the outlet flue 1 A mechanical filter 2 is arranged on the top, and the mechanical filter 2 can be types such as shutters, filter screens or cloth bags. The bottom of the evaporation tower barrel 3 is provided with a scraper slag remover 6 for discharging the large particles deposited at the bottom of the tower.

There is a flue gas inlet on the cylinder body 3 of the evaporation tower, and an inlet flue 7 is connected to the flue gas inlet shown. The center line of the inlet flue 7 is circumscribed with an imaginary circle in the cylinder body 3 of the evaporation tower. The center of the circle is located on the center line of the evaporation tower cylinder body 3, and its radius is 0.2-0.8 times of the radius of the evaporation tower cylinder body 3, and the imaginary circle is arranged horizontally, that is, the imaginary circle and the evaporation tower cylinder body 3 The cross-section of is parallel, and for the convenience of description, the imaginary circle is set as the reference imaginary circle.

The inner wall of the evaporation tower cylinder body 3 is provided with at least one circle of atomizing nozzles along the height direction, and each circle of atomization nozzles includes a plurality of atomization nozzles 4, and the plurality of atomization nozzles 4 in each circle of atomization nozzles are arranged along the evaporation tower cylinder. The inner wall of the body 3 is arranged circumferentially, and the circle of atomizing nozzles closest to the bottom of the evaporation tower cylinder body 3 is located above the inlet flue 7, and a plurality of atomizing nozzles 4 in the circle of atomizing nozzles are outside the center line of the nozzle outlet. cut to the imaginary circle.

As an optimization, the inner wall of the evaporation tower body 3 can be provided with multiple circles of atomizing nozzles along the height direction, the spacing between two adjacent circles of atomizing nozzles is equal, and the distance between two adjacent atomizing nozzles 4 in each circle of atomizing nozzles equal. Among the multiple circles of atomizing nozzles, the outlet centerlines of the multiple atomizing nozzles 4 in the circle closest to the bottom of the evaporation tower body 3 are circumscribed on the reference imaginary circle. The atomizing nozzles in each circle are arranged in a downstream or intersecting manner, and the center line of the outlet of multiple atomizing nozzles in each circle can circumscribe an imaginary circle clockwise or counterclockwise, and the center of the imaginary circle in each circle They are all located on the center line of the evaporation tower body 3, and the radii of all imaginary circles and reference imaginary circles are equal, and the distance between two adjacent imaginary circles is equal to the distance between two adjacent circles of atomizing nozzles.

A circle of air nozzles 5 is also provided on the inner wall of the evaporation tower body 3 in the circumferential direction. A circle of air nozzles 5 is located below the inlet flue 7 and includes a plurality of air nozzles 5. The outlet centerlines of the plurality of air nozzles 5 are inclined to the reference The boundary line of the imaginary circle.

The direction of rotation of the fine liquid droplets ejected from the atomizing nozzle 4 is opposite to the direction of rotation of the flue gas ejected from the inlet flue 7 . Specifically, when the centerlines of the nozzle outlets of a plurality of atomizing nozzles 4 in the atomizing nozzles 4 circumscribe an imaginary circle counterclockwise (when there are multiple circles of atomizing nozzles, the centerlines of the outlets of the atomizing nozzles in each circle are counterclockwise circumscribe the corresponding imaginary circle), the center line of the inlet flue 7 is circumscribed clockwise to the corresponding imaginary circle, so that the rotation direction of the fine liquid droplets sprayed from the atomizing nozzle 4 is the same as that of the sprayed from the inlet flue 7 The rotation direction of the flue gas is opposite, which strengthens the mixing of the flue gas and fine liquid droplets (the waste water becomes fine liquid droplets after atomization) and enhances the heat exchange. In addition, due to the suction of the outlet flue of the evaporation tower cylinder, the air flow is forced to rise, and as a result, a rotating upward airflow is formed in the evaporation tower cylinder. The inlet flue can also be arranged in a clockwise circle or branched into a plurality of branches.

Waste water evaporation tower provided by the present invention can comprise the steps during use:

1) Waste water and compressed air are sprayed into the evaporation tower cylinder body 3 through the atomizing nozzle 4 according to a certain ratio. Specifically, a waste water pipe A1 and a compressed air pipe A2 can be set. The waste water pipe A1 and the compressed air pipe A2 communicated with the atomizing nozzle;

2) After the waste water enters the atomizing nozzle 4, it is atomized into fine droplets in the evaporation tower, and the fine droplets are mixed with flue gas and hot air in the evaporation tower and heated to the saturation temperature until it is evaporated to dryness; compression The pressure ratio of the air and waste water entering the atomizing nozzle 4 is 0.25-0.6, and the particle size of the fine droplets atomized by the atomizing nozzle 4 is 0-200 μm, and the velocity is 50-100 m/s.

3) High-temperature flue gas enters the evaporation tower cylinder 3 through the inlet flue 7 and fully mixes with the sprayed atomized wastewater.

4) Hot air is sprayed into the evaporation tower cylinder body 3 through the air nozzle 5 to strengthen the disturbance of the air flow in the evaporation tower cylinder body, strengthen the heat exchange between waste water and flue gas, accelerate the evaporation of fine droplets, and reduce the evaporation time, which can Further control the reduction range of the flue gas temperature in the evaporation tower to ensure that the temperature of the flue gas in the evaporation tower is above the acid dew point temperature of the flue gas, so as to prevent the liquid from accumulating at the bottom, causing corrosion of the evaporation tower body and ash adhesion Together.

5) Fine particles in the flue gas collide and agglomerate with the residue after the waste water is evaporated to dryness, forming large particles, which are deposited on the bottom of the dry tower cylinder under the action of gravity and centrifugal force, and are set on the dry tower cylinder The scraper slag remover 6 at the bottom is discharged, and other small particles are filtered through the mechanical filter 2 at the bottom of the outlet flue 1 (also located at the top of the evaporation tower cylinder) with the flue gas, and then enter through the outlet flue 1 It is removed in the electrostatic precipitator.

Embodiment 2: In consideration of the actual situation of the arrangement of flues in industries such as iron and steel, papermaking and coal gasification, it can be considered to adopt the desulfurization wastewater evaporation tower structure shown in accompanying drawing 4, and the desulfurization wastewater evaporation tower structure is the same as that in embodiment 1. The only differences in the evaporation tower for treating desulfurization wastewater from thermal power plants are as follows:

1. The bottom of the outlet flue 1 extends all the way to the cylinder body 3 of the evaporation tower, specifically the part between the atomizing nozzle 4 and the air nozzle 5 in the cylinder body 3 of the evaporation tower. Under the action of gravity, the high-temperature flue gas entering the evaporation tower body 3 from the inlet flue 7 forces the airflow to descend, and because the bottom of the outlet flue 1 is located at the lower part of the evaporation tower body, under its draft and high temperature flue gas The gravitational effect of gas results in the formation of a rotating downdraft in the evaporation tower cylinder body 3.

2. The part between the top of the evaporation tower body 3 and the atomization nozzle 4 on the evaporation tower body 3 has a flue gas inlet, and the shown flue gas inlet is connected with an inlet flue 7 .

Finally, it is noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (4)

1. process heat-engine plant desulfurized waste water evaporate to dryness tower for one kind, it is characterized in that: comprise evaporate to dryness tower cylindrical shell (3), the top of described evaporate to dryness tower cylindrical shell (3) has exhanst gas outlet, shown in be communicated with exhaust pass (1) on exhanst gas outlet, the bottom of described exhaust pass (1) is positioned at the top of evaporate to dryness tower cylindrical shell (3), and the bottom of exhaust pass (1) is provided with mechanical filter (2);

The bottom of described evaporate to dryness tower cylindrical shell (3) is provided with the scraper slag removing machine (6) for the macrobead thing being deposited at the bottom of tower is discharged;

On described evaporate to dryness tower cylindrical shell (3), there is smoke inlet, shown in be communicated with gas approach (7) on smoke inlet, the interior imaginary circle of the medullary ray of this gas approach (7) and evaporate to dryness tower cylindrical shell (3) is circumscribed, the center of circle of described imaginary circle is positioned on the medullary ray of evaporate to dryness tower cylindrical shell (3), its radius is 0.2-0.8 times of evaporate to dryness tower cylindrical shell (3) radius, and, this imaginary circle arranged transversely;

The inwall of described evaporate to dryness tower cylindrical shell (3) is at least provided with a circle atomizing nozzle along short transverse, every circle atomizing nozzle comprises multiple atomizing nozzles (4), multiple atomizing nozzles (4) in every circle atomizing nozzle circumferentially arrange along the inwall of evaporate to dryness tower cylindrical shell (3), a circle atomizing nozzle nearest apart from evaporate to dryness tower cylindrical shell (3) bottom is positioned at the top of gas approach (7), and the center line of discharge of multiple atomizing nozzles (4) in this circle atomizing nozzle is cut in described imaginary circle outward;

The inwall of described evaporate to dryness tower cylindrical shell (3) is circumferentially also provided with a circle tuyere (5), a described circle tuyere (5) is positioned at the below of gas approach (7) and comprises multiple tuyeres (5), and described multiple tuyeres (5) center line of discharge tilts to point to the boundary line of described imaginary circle.

2. the heat-engine plant desulfurized waste water evaporate to dryness of processing according to claim 1 tower, is characterized in that: the sense of rotation of the fine drop of described atomizing nozzle (4) ejection is contrary with the sense of rotation of the flue gas from gas approach (7) ejection.

3. the heat-engine plant desulfurized waste water evaporate to dryness of processing according to claim 1 tower, is characterized in that: the inwall of described evaporate to dryness tower cylindrical shell (3) is provided with multi-turn atomizing nozzle along short transverse, and the spacing of two adjacent rings atomizing nozzle equates.

4. according to the heat-engine plant desulfurized waste water evaporate to dryness of the processing described in claim 1 or 3 tower, it is characterized in that: in every circle atomizing nozzle, the spacing of adjacent two atomizing nozzles (4) equates.