CN204841409U - High -efficient gradual change is compound desulfurizing tower in grades - Google Patents

Abstract

The utility model discloses a high-efficiency gradient graded composite desulfurization tower, which comprises a tower body. The tower body includes an oxidation crystallization section, a rough desulfurization and dust removal section, a fine desulfurization and dust removal section and a horizontal demisting section from bottom to top; the oxidation crystallization section It includes a pulp tank, a separation mechanism arranged in the pulp tank and dividing the pulp tank into upper and lower areas; the rough desulfurization and dust removal section includes a gas distribution plate and a multi-layer spray layer arranged above the flue gas inlet, and the spray The layer is connected to the slurry tank; the fine desulfurization and dust removal section includes a tube type demister, a flushing layer, a thin film liquid-holding layer, and a liquid-holding layer circulation tank, and the pH value of the slurry in the liquid-holding layer circulation tank is greater than that of the slurry in the slurry tank pH value. The utility model is used for processing medium-high sulfur coal and high-sulfur coal flue gas, has extremely high desulfurization efficiency and dust removal performance, and the desulfurization efficiency exceeds 99%.

Description

High-efficiency graded compound desulfurization tower

technical field

The utility model relates to a desulfurization tower, in particular to a high-efficiency gradient graded composite desulfurization tower.

Background technique

In recent years, my country's coal-fired power plants have generally adopted medium and low-sulfur coals with high prices, low sulfur content, low ash content, and high calorific value in order to respond to the national environmental protection limit pressure, which is suitable for medium and low-sulfur coal. (Sar<1.5%) ultra-low emission technology has been successfully put into operation. However, so far, there have been no successful cases of ultra-low emission technology suitable for medium-high and high-sulfur coal (Sar>1.5%) put into operation.

However, in my country's coal resources, about 30% of the coal has a sulfur content of more than 2%, especially in some coal mines in Southwest China, where the sulfur content is as high as 10%. Coal with a sulfur content of more than 2%; at the same time, with the increasing use of high-quality coal, coal-fired power plants in my country will have to face the situation that low-sulfur coal is decreasing and fuel costs are rising, and they are forced to use medium-high and high-sulfur coal ; In addition, the national and local governments have stepped up efforts to control the concentration of pollutants emitted by thermal power plants, and proposed a series of strict emission standards in history. These strict standards also require high-performance desulfurization technology with deep desulfurization and efficient dust removal.

Coal-fired flue gas contains a large amount of SO ₂ , soot, and a small amount of HCl, HF, SO ₃ , heavy metals and other pollutants. At present, wet flue gas desulfurization devices are most used in flue gas desulfurization. Limestone-gypsum wet method is the most widely used. The main function of the limestone-gypsum desulfurization tower is to remove SO ₂ , and it also has the auxiliary function of removing soot and other pollutants. Generally, the desulfurization efficiency requirement of wet desulfurization is 90% to 95%. In China, there are successful operation cases with a desulfurization efficiency of 98%, but there is no precedent for the use of wet desulfurization devices that use high-sulfur coal units that can meet the emission requirements of gas-fired units. However, foreign wet desulfurization devices do not have such high-performance desulfurization requirements because the total amount of coal-fired units is not large (compared with domestic ones).

For medium-high-sulfur coal and high-sulfur coal, the desulfurization efficiency must exceed 99%, and even higher desulfurization efficiency is required to reduce the SO ₂ content in the flue gas at the outlet of the desulfurization device to below 35 mg/Nm ³ . Therefore, developing a new type of desulfurization tower, improving the deep desulfurization performance of the desulfurization tower, making the SO ₂ in the exhaust flue gas less than 35mg/Nm ³ , and even achieving ultra-low SO ₂ emission of less than 20mg/Nm ³ is a solution to medium-high sulfur coal, The important task of high-sulfur coal flue gas treatment has a positive effect on solving the haze problem and improving air quality.

The limestone-gypsum desulfurization tower generally adopts the form of a single spray tower and is arranged in a countercurrent manner. The flue gas enters the absorption tower from the upper part of the slurry tank through the inlet of the absorption tower, passes through the spray layer and demister in turn, and is discharged through the chimney. The slurry is ejected from multiple nozzles in each spray layer, moves downward, and has physical and chemical effects in countercurrent contact with the flue gas to wash and remove sulfur dioxide in the flue gas. Dust is captured by inertial collision, interception, diffusion, condensation and gravity settlement. The slurry absorbs sulfur oxides SO ₂ , soot and other pollutants from the flue gas, and then falls into the slurry tank in the lower section of the desulfurization tower, where it is forced to oxidize and crystallize.

There are two main reasons why the desulfurization efficiency of conventional limestone-gypsum desulfurization devices is limited: 1) Limited by conditions such as gypsum oxidation and crystallization, limestone dissolution and consumption control, the pH value of the absorption slurry is usually between 5.2 and 5.8 , which limits the activity of the absorbent; 2) limited by the single tower, the total flow rate of the absorbing slurry cannot be too large, otherwise it will cause the liquid overload in the tower, resulting in a sharp increase in the flue pressure drop, making it impossible to operate.

In order to solve the above problems, the series tower technology has been applied to a certain extent. The series absorption tower is to connect two absorption towers in series through the flue. The flue gas from the induced draft fan of the boiler first enters the first-stage absorption tower, and part of the SO2 in the flue gas is removed after being washed by the first _- stage absorption tower. The desulfurization efficiency is generally 30-80%, and the pH of the slurry is controlled at 4.5-5.3 , The main function of this level of absorption is to ensure excellent calcium sulfite oxidation effect and sufficient gypsum crystallization time. Especially for high-sulfur coal, the oxidation air coefficient can be greatly reduced, thereby greatly reducing the power consumption of the oxidation fan, and at the same time can greatly improve the quality of gypsum and increase the dehydration rate of gypsum. The flue gas enters the second-stage absorption tower after coming out of the first-stage absorption tower. The second-stage absorption tower is the main desulfurization and washing process. Since there is no need to consider the problem of oxidation crystallization, the pH can be controlled at a very high level, reaching 5.8~ 6.4, which makes full use of the efficient removal of SO ₂ by the absorbent, and reduces the SO ₂ content in the flue gas at the outlet of the desulfurization tower to a smaller range.

Although the tandem tower technology has achieved the ultra-high desulfurization efficiency of medium-high sulfur coal and high-sulfur coal to a certain extent, and solved the problem of their emission standards, the tandem tower technology also has many disadvantages: 1) The initial investment of the project is high; 2) due to the setting The two-stage absorption tower occupies a large area. For the transformation of existing devices, a large number of projects cannot be implemented; 3) There are relatively many equipment, high failure rate of equipment, heavy maintenance workload, and high operating costs.

Utility model content

The purpose of the utility model is to provide a high-efficiency gradient graded composite desulfurization tower, which is used for processing medium-high sulfur coal and high-sulfur coal flue gas, has extremely high desulfurization efficiency and dust removal performance, and the desulfurization efficiency exceeds 99%.

The technical scheme that the utility model solves its technical problem adopts is:

Provide a high-efficiency gradient graded composite desulfurization tower, the desulfurization tower includes a tower body, the middle part of the tower body is provided with a flue gas inlet, the top of the tower body is provided with a flue gas outlet, and the tower body includes oxidation gas from bottom to top. Crystallization section, coarse desulfurization and dust removal section, fine desulfurization and dust removal section and horizontal demisting section; among them,

The oxidation crystallization section includes a slurry tank arranged at the bottom of the tower body, and a separation mechanism horizontally arranged in the slurry tank and dividing the slurry tank into upper and lower areas. The air distribution pipe is provided with a plurality of agitators in the lower crystallization area;

The coarse desulfurization and dust removal section includes a gas distribution plate arranged above the flue gas inlet, and a multi-layer spray layer arranged above the gas distribution plate, and the spray layer is connected to the crystallization area of the slurry pool;

The fine desulfurization and dust removal section includes a tube type mist eliminator, a flushing layer arranged above the tube type mist eliminator, a thin film liquid-holding layer disposed above the flushing layer, and a The liquid-holding layer circulation tank, the thin-film liquid-holding layer includes a liquid collector, an S-type gas-liquid mass transfer mechanism and a liquid distributor arranged sequentially from bottom to top, and the liquid collector is connected to the inlet of the liquid-holding layer circulation tank, The outlet of the liquid-holding layer circulation tank is connected to a liquid distributor through a liquid-holding layer circulation pump, and the pH value of the slurry in the liquid-holding layer circulation tank is greater than that in the slurry tank.

According to the above technical solution, the separation mechanism is a perforated plate or a plurality of row pipes placed side by side.

According to the above technical solution, a gas-liquid mass transfer synergistic ring is arranged on the inner wall of the tower below each spray layer, and the vertical section of the gas-liquid mass transfer synergistic ring is triangular.

According to the above technical solution, the height of the gas-liquid mass transfer synergistic ring is 300-2000 mm.

According to the above technical solution, the nozzles on the spray layer are single-headed nozzles or double-headed atomizing nozzles.

According to the above technical solution, the slurry tank is equipped with gypsum slurry, and the pH value of the gypsum slurry is 5.2-5.8.

According to the above technical solution, the liquid-holding layer circulation tank is filled with limestone slurry, and the pH value of the limestone slurry is 5.8-6.4.

According to the above technical solution, the S-shaped gas-liquid mass transfer mechanism is formed by arranging a plurality of elongated plates with transverse S-shaped cross-sections side by side, and the S-shaped ends between adjacent plates are interlaced and arranged at intervals. The intervals form the airflow lanes.

According to the above technical solution, trapezoidal, rectangular or triangular air outlets are provided on the lower edge of the S-shaped end of the plate body.

According to the above technical solution, the horizontal defogging section includes 1-4 levels of horizontal flue demisters, and the demisters are provided with independent water washing and water recovery units.

The utility model has the following beneficial effects: the desulfurization tower adopts the gradient graded compound desulfurization technology, has extremely high desulfurization efficiency and dust removal performance, the desulfurization efficiency reaches more than 99%, and the dust removal efficiency reaches more than 90%, which is suitable for processing medium and high sulfur coal. , High-sulfur coal flue gas, especially the treatment of high-sulfur coal flue gas. At the same time, because the desulfurization tower is a single tower, it is especially suitable for the transformation of existing desulfurization devices with narrow areas and limited land occupation.

Description of drawings

The utility model will be further described below in conjunction with accompanying drawing and embodiment, in the accompanying drawing:

Fig. 1 is the structural representation of the utility model;

Fig. 2 is the structural representation of S-type gas-liquid mass transfer mechanism in the utility model;

Fig. 3 is the structural representation of liquid distributor in the utility model;

Fig. 4 is the structural representation of liquid collector in the utility model;

Fig. 5 is a schematic structural view of the gas-liquid mass transfer synergistic ring in the utility model;

Fig. 6 is the structural representation of the gas distribution plate in the utility model;

Fig. 7 is a schematic structural view of an embodiment of the separation mechanism in the utility model;

Fig. 8 is a structural schematic diagram of another embodiment of the separation mechanism in the present invention.

In the figure: 1-flue gas inlet, 2-gas distribution plate, 3-spray layer, 4-gas-liquid mass transfer synergistic ring, 5-pipe demister, 6-washing layer, 7-liquid collector, 8-S-type gas-liquid mass transfer mechanism, 801-plate body, 9-liquid distributor, 10-horizontal flue demister, 11-flue gas outlet, 12-liquid holding layer circulation tank, 13-liquid holding layer circulation Pump, 14-stirrer, 15-oxidation air distribution pipe, 16-separation mechanism, 1601-perforated plate, 1602-pipe, 17-tower body.

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

In a preferred embodiment of the present utility model, as shown in Figures 1-8, a high-efficiency gradient graded composite desulfurization tower includes a tower body 17, and a flue gas inlet 1 is provided in the middle of the tower body 17. The top of the body 17 is provided with a flue gas outlet 11, and the tower body 17 includes an oxidation crystallization section, a rough desulfurization and dust removal section, a fine desulfurization and dust removal section, and a horizontal demisting section from bottom to top; wherein,

The oxidation and crystallization section includes a slurry tank arranged at the bottom of the tower body 17, and a separation mechanism 16 arranged horizontally in the slurry tank and dividing the slurry tank into upper and lower areas. A plurality of oxidation air distribution pipes 15 are arranged in the upper oxidation zone. , a plurality of stirrers 14 are arranged in the lower crystallization zone;

The coarse desulfurization and dust removal section includes a gas distribution plate 2 arranged above the flue gas inlet 1, a multi-layer spray layer 3 arranged above the gas distribution plate 2, and the spray layer 3 is connected to the crystallization area of the slurry tank;

The fine desulfurization and dust removal section includes a tube type mist eliminator 5, a flushing layer 6 arranged above the tubular type mist eliminator 5, a thin-film liquid-holding layer arranged above the flushing layer 6, and a liquid-holding layer circulation connected to the thin-film liquid-holding layer The tank 12, the thin-film liquid-holding layer includes a liquid collector 7, an S-type gas-liquid mass transfer mechanism 8, and a liquid distributor 9 arranged sequentially from bottom to top. The liquid collector 7 is connected to the inlet of the liquid-holding layer circulation tank 12, and the liquid-holding layer The outlet of the layer circulation tank 12 is connected to the liquid distributor 9 through the liquid-holding layer circulation pump 13, and the pH value of the slurry in the liquid-holding layer circulation tank 12 is greater than the pH value of the slurry in the slurry tank.

In a preferred embodiment of the present utility model, as shown in FIG. 7 and FIG. 8 , the separation mechanism 16 is a perforated plate 1601 or a plurality of row pipes 1602 placed side by side.

In a preferred embodiment of the present utility model, as shown in Fig. 1 and Fig. 5, a gas-liquid mass transfer synergistic ring 4 is arranged on the inner wall of the tower body 17 below each spray layer 3, and the gas-liquid mass transfer synergistic ring The vertical section of 4 is triangular, wherein the height of gas-liquid mass transfer synergistic ring 4 is 300-2000mm.

In a preferred embodiment of the present invention, as shown in FIG. 1 , the nozzles on the spray layer 3 are single-headed nozzles or double-headed atomizing nozzles.

In a preferred embodiment of the present invention, as shown in Figure 1, the slurry tank is filled with gypsum slurry, and the pH value of the gypsum slurry is 5.2-5.8.

In a preferred embodiment of the present invention, as shown in FIG. 1 , the liquid-holding layer circulation tank 12 is filled with limestone slurry, and the pH value of the limestone slurry is 5.8-6.4.

In a preferred embodiment of the present utility model, as shown in Fig. 1 and Fig. 2, the S-type gas-liquid mass transfer mechanism 8 is formed by arranging a plurality of elongated plates 801 with transverse S-shaped cross-sections, adjacent to each other. The S-shaped ends of the plate bodies 801 are interlaced and arranged at intervals, and the intervals form the airflow channels. In order to evenly distribute the smoke and improve the adaptability to gas load fluctuations, trapezoidal, rectangular or triangular air outlets are provided on the lower edge of the end of the plate body 801S.

In a preferred embodiment of the present utility model, as shown in Fig. 1, the horizontal demisting section includes 1 to 4 levels of horizontal flue demisters 10, and the demisters are provided with independent water washing and water recovery units.

When the utility model is in use, the pulp tank at the bottom is divided into an oxidation zone and a crystallization zone by a separation mechanism, and an oxidation air distribution pipe is set in the oxidation zone to ensure efficient oxidation of calcium sulfite in the pulp tank, and the oxidation air distribution tube adopts Alloy materials or non-metallic materials; and the relatively independent crystallization area can make the crystal particles of gypsum grow larger, which is not only beneficial to the operation of the subsequent dehydration system, but also ensures the effect of demisting and improves the efficiency of desulfurization and dust removal; in addition, the crystallization area An agitator or other turbulent stirring mechanism can be set inside to prevent gypsum from depositing and scaling.

The utility model adopts the gradual graded compound desulfurization technology, adopts different absorbents in different positions of the desulfurization tower, and the pH value of the slurry increases gradually from bottom to top, especially in the fine desulfurization and dust removal section, limestone slurry is used as the absorbent, and the pH can be controlled At a very high level, reaching 5.8-6.4, making full use of its high activity, the liquid-holding layer circulation tank provides limestone slurry with a higher pH value to the thin-film liquid-holding layer. The absorbent used in the spray layer is limestone-gypsum mixed slurry, and the content of limestone in the mixed solution gradually increases from bottom to top, so the pH value of the mixed slurry also increases from bottom to top.

When working, the flue gas enters the tower through the flue gas inlet, first diffuses along the gas distribution plate (the gas distribution plate is a porous plate) under the obstruction of the gas distribution plate, so that the flue gas and The flow rate of the flue gas with a smaller flow rate is remixed to achieve the effect of flow redistribution, so that the flue gas after passing through the gas distribution plate is evenly distributed on the cross-section of the tower body, which plays the role of uniform flue gas distribution and can solve the problem of flue gas deviation. problem, improve the efficiency of desulfurization and dust removal; then carry out coarse desulfurization and dust removal under the action of the spray layer. The inner side of the tower wall under the first spray layer is provided with a gas-liquid mass transfer synergistic ring. The nozzles on the spray layer are single-head nozzles or double-head atomizing nozzles. If a double-head atomizing nozzle is used, the two outlets will spray out The spray direction can be the same or opposite.

The fine desulfurization and dust removal section intercepts a large amount of gypsum slurry through the tube demister, and then through the S-type gas-liquid mass transfer mechanism, which can further improve the mass transfer effect, so that the whole tower has extremely high desulfurization efficiency and dust removal performance. The desulfurization efficiency can be over 99%. The SO ₂ content at the inlet of the desulfurization tower is 6500 mg/Nm ³ , and the SO ₂ content at the outlet of the desulfurization tower can be reduced to below 35 mg/Nm ³ . When the SO ₂ content at the inlet of the desulfurization tower is 5000 mg/Nm ³ , _The SO2 content at the outlet of the desulfurization tower can be reduced to less than 20mg/ ^Nm3 , which realizes the deep desulfurization of the desulfurization tower. In addition, the nozzle of the flushing layer faces upwards to wash the lower part of the liquid-holding layer of the film to prevent fouling of the lower part of the liquid-holding layer of the film . At the same time, the gas containing SO ₂ and soot enters the limestone film slurry layer through the S-type gas-liquid mass transfer mechanism (the height of the limestone slurry liquid film _on the liquid-holding layer of the film is 20-150 mm), and a large number of bubbles are aroused to form a foam layer. The foam layer is absorbed by the slurry, while the smoke is constantly disturbed by the foam under the action of inertia and diffusion, and constantly changes direction, increasing the contact probability of the smoke and liquid, and the smoke is purified. The dust removal effect of the bubble dust collector is higher than that of the spray tower dust collector, especially the performance of removing fine dust of PM2.5 and below is very high, which is much higher than the dust removal efficiency of the spray layer. Therefore, the dust removal efficiency of the utility model is increased from 50% of the ordinary desulfurization tower to more than 90%, and the dust content at the outlet of the desulfurization tower can be reduced to below 5mg/Nm ³ .

It should be understood that those skilled in the art can make improvements or changes based on the above description, and all these improvements and changes should belong to the protection scope of the appended claims of the present utility model.

Claims (10)

1. A high-efficiency gradually-changed graded composite desulfurizing tower comprises a tower body (17), wherein a flue gas inlet (1) is formed in the middle of the tower body (17), and a flue gas outlet (11) is formed in the top of the tower body (17), and is characterized in that the tower body (17) comprises an oxidation crystallization section, a coarse desulfurization dust removal section, a fine desulfurization dust removal section and a horizontal demisting section from bottom to top; wherein,

the oxidation crystallization section comprises a slurry tank arranged at the bottom of a tower body (17) and a separating mechanism (16) which is horizontally arranged in the slurry tank and divides the slurry tank into an upper zone and a lower zone, a plurality of oxidation air distribution pipes (15) are arranged in the oxidation zone at the upper part, and a plurality of stirrers (14) are arranged in the crystallization zone at the lower part;

the coarse desulfurization dust removal section comprises a gas distribution plate (2) arranged above a flue gas inlet (1) and a plurality of spraying layers (3) arranged above the gas distribution plate (2), and the spraying layers (3) are connected with a crystallization area of a slurry tank;

the fine desulfurization dust removal section comprises a tubular demister (5), a flushing layer (6) arranged above the tubular demister (5), a membrane liquid holding layer arranged above the flushing layer (6), and a liquid holding layer circulating tank (12) connected with the membrane liquid holding layer, wherein the membrane liquid holding layer comprises a liquid collector (7), an S-shaped gas-liquid mass transfer mechanism (8) and a liquid distributor (9) which are sequentially arranged from bottom to top, the liquid collector (7) is connected with an inlet of the liquid holding layer circulating tank (12), an outlet of the liquid holding layer circulating tank (12) is connected with the liquid distributor (9) through a liquid holding layer circulating pump (13), and the pH value of slurry in the liquid holding layer circulating tank (12) is greater than that of the slurry in the slurry tank.

2. The desulfurization tower of claim 1, wherein the separation means (16) is a perforated plate or a plurality of rows of tubes placed side by side.

3. The desulfurization tower of claim 1, wherein a gas-liquid mass transfer efficiency-increasing ring (4) is arranged on the inner wall of the tower body (17) below each spray layer (3), and the vertical section of the gas-liquid mass transfer efficiency-increasing ring (4) is triangular.

4. The desulfurization tower of claim 3, wherein the height of the gas-liquid mass transfer synergistic ring (4) is 300-2000 mm.

5. The desulfurization tower of claim 1, wherein the spray nozzles of the spray layer (3) are single-head nozzles or double-head atomizing nozzles.

6. The desulfurization tower of claim 1, wherein the slurry tank contains gypsum slurry, and the gypsum slurry has a pH value of 5.2-5.8.

7. The desulfurization tower according to claim 1, wherein the liquid-holding layer circulation tank (12) contains a limestone slurry having a pH of 5.8 to 6.4.

8. The desulfurization tower of claim 1, wherein the S-shaped gas-liquid mass transfer mechanism (8) is formed by arranging a plurality of elongated plate bodies (801) with cross sections in a transverse S shape in parallel, and the S-shaped end parts of the adjacent plate bodies (801) are staggered and arranged at intervals, and the intervals form gas flow channels.

9. The desulfurization tower of claim 8, wherein the S-shaped end of the plate body (801) is provided with trapezoidal, rectangular or triangular gas outlet holes at the lower edge.

10. The desulfurization tower of claim 1, wherein said horizontal demisting stage comprises a 1-4 stage horizontal flue mist eliminator (10) provided with a separate water wash and water recovery unit.