Dense-thin separation ultra-low emission desulfurization system

Abstract

The utility model relates to a thick-thin separation ultra-low emission desulfurization system which comprises a thick tower, a thin tower, a thick liquid circulating pool and a thick liquid circulating pump which are communicated with one another, concentration towers and dilution towers with the corresponding number are correspondingly arranged, one concentration tower corresponds to one dilution tower, a plurality of concentration towers and a plurality of dilution towers are parallel, discharged liquid of all dilution towers enters the same concentrated liquid circulating pool, and concentrated liquid of all concentration towers also enters the same concentrated liquid circulating pool. Gypsum slurry is uniformly discharged from the concentrated liquid circulating pool by a gypsum discharge pump to a public gypsum dehydration system for dehydration; according to the utility model, SO2 in boiler flue gas is eluted by connecting the thick tower and the light tower in series, a plurality of boilers share one thick liquid circulating pool, and a thick-thin separation state of high concentration and low PH value of thick tower slurry and low concentration and high PH value of light tower slurry is kept during operation, so that desulfurization is efficiently graded from the source, the generation concentration of particulate matters in the desulfurization tower is reduced, and the desulfurization efficiency is improved. The method has the advantages of high desulfurization efficiency, low desulfurization agent consumption and the like.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the field of boiler flue gas desulfurization technology, especially relates to a thick and thin separation ultra-low emission desulfurization system. BACKGROUND

[0002] In order to meet the increasingly stringent environmental requirements, the industry begins to develop and apply more efficient desulfurization technology.

[0003] The patent application file with the publication number CN204469527U discloses a series connection double-tower wet desulfurization device, which comprises a raw flue gas channel, a purification flue and a spray tower. The inside of the spray tower is provided with a spray layer to spray the absorbent contained in the bottom of the spray tower. Among them, the spray tower is two, one of which is communicated with the raw flue gas channel, the flue gas outlet of which is communicated with the flue gas inlet of the other spray tower, and the flue gas outlet of the other spray tower is communicated with the purification flue. After the flue gas passes through the first spray tower, it enters the other spray tower for desulfurization. The flue gas can stay in the double spray tower for a longer time, which prolongs the contact reaction time of sulfur dioxide and the absorbent, thereby improving the desulfurization efficiency. The single spray tower considers the desulfurization efficiency in the process design, which can slightly reduce the total desulfurization efficiency, and can reduce the spray density and the circulating amount of the circulating pump for pumping the absorbent, thereby reducing the energy consumption. Therefore, the above-mentioned series connection double-tower wet desulfurization device can effectively reduce the energy consumption, but the slurry is not separated into thick (low PH value of 4.5-5.4, high concentration of density 1.2-1.3 t / m3) and thin (high PH value of 6.5-7.0, low concentration of density 1.05-1.15 t / m3), and the gypsum slurry is not concentrated by the thick tower and collected in a pool body for centralized removal, thereby producing the following problems:

[0004] 1. When multiple boiler desulfurization systems are running at the same time, it is impossible to realize simultaneous and non-differential desulfurization of multiple desulfurization towers.

[0005] 2. During the operation process, the SO2 and particulate matter at the outlet of the desulfurization tower cannot be stably reached to the ultra-low emission standard for a long time.

[0006] 3. During the operation process of the desulfurization tower, the PH value of the slurry is high, the calcium sulfite is not fully oxidized, the gypsum quality is poor, the dehydration is difficult, and the material balance in the tower is difficult to control.

[0007] 4. During the operation process of the ultra-low emission, the consumption of the desulfurizer is 3 times that of the non-ultra-low emission condition (SO2≤200 mg / m 3 ).

[0008] 5. If the desulfurizer desulfurization reaction shielding area occurs in the single tower, the desulfurization slurry supply must be stopped, and even the boiler must be stopped, which affects the operation of the boiler and the environmental protection standard emission. SUMMARY

[0009] In order to overcome the above prior art, the utility model discloses a purpose at providing a kind of thick and thin separation ultra-low emission desulfurization system, by thick tower and dilute tower grade desulfurization tower series connection to the SO2 in boiler flue gas is washed and is removed, comprehensively slurry concentration separation, slurry PH value separation two kinds of technology, from source, make desulfurization high-efficiency classification, and reduce the concentration of particulate matter in desulfurization tower, improve the desulfurization efficiency, reduce desulfurizer consumption, make the SO2 of desulfurization tower export, particulate matter long-term stable standard.

[0010] In order to realize the above-mentioned purpose, the technical scheme adopted by the utility model is:

[0011] A kind of thick and thin separation ultra-low emission desulfurization system, including the intercommunication of thick tower 1, dilute tower 2, thick liquid circulating pool 3 and thick liquid circulating pump 4;

[0012] The thick tower 1 is used to remove SO2 in boiler flue gas in the first stage;

[0013] The dilute tower 2 is used to remove SO2 in the flue gas exported by thick tower 1 in the second stage;

[0014] The thick liquid circulating pool 3 is used to store thick liquid discharged after being used by thick tower 1 to remove SO2 in boiler flue gas in the first stage, and dilute liquid discharged after being used by dilute tower 2 to remove SO2 in the flue gas exported by thick tower 1 in the second stage;Meanwhile, according to the PH value of the thick liquid and the dilute liquid mixed after being used in thick liquid circulating pool 3, new desulfurization lime slurry is added as needed, fully mixed, to form mixed desulfurization slurry, i.e. "desulfurization thick liquid";

[0015] The thick liquid circulating pump 4 is used to circulate and deliver the desulfurization thick liquid in thick liquid circulating pool 3 to thick tower 1.

[0016] The thick tower 1 and dilute tower 2 are arranged as multiple groups, each group comprising one thick tower 1 and one dilute tower 2;All thick towers 1 are in communication with thick liquid circulating pool 3, and all dilute towers 2 are in communication with the same thick liquid circulating pool 3, and the thick tower gypsum discharge pump 7 is externally connected to the dehydration system through the thick liquid circulating pool 3.

[0017] A first flue gas inlet 1-1 is formed in the middle and lower part of one side of the thick tower 1, and a first liquid inlet 1-3 is formed in the top of the thick tower 1, the boiler flue gas enters the thick tower 1 through the first flue gas inlet 1-1, and the thick liquid flowing out of the thick liquid circulating pool 3 flows into the thick tower 1 through the first liquid inlet 1-3 to contact, and SO2 in the boiler flue gas is removed in the first stage, a first flue gas outlet 1-2 is formed in the other side of the thick tower 1, the flue gas exported by the thick tower 1 enters the dilute tower 2 through the first flue gas outlet 1-2, and a first liquid outlet 1-4 is formed in the bottom of the thick tower 1, and the first liquid outlet 1-4 is in communication with the thick liquid circulating pool 3;

[0018] The one side of the dilute tower 2 is provided with a second flue gas inlet 2-1 communicated with the first flue gas outlet 1-2 of the concentration tower 1, the flue gas outputted by the concentration tower 1 enters the dilute tower 2 through the second flue gas inlet 2-1, and the dilute tower 2 carries out second-stage removal of SO2 in the flue gas; the other side of the dilute tower 2 is provided with a third liquid inlet 2-3 at the upper portion, the other side of the dilute tower 2 is provided with a slurry circulating outlet 2-6 at the lower portion, the slurry circulating outlet 2-6 is communicated with the third liquid inlet 2-3 of the dilute tower 2 through a dilute tower circulating pump 9, the bottom of the dilute tower 2 is provided with a second liquid outlet 2-2, and the second liquid outlet 2-2 is communicated with the concentration liquid circulating pool 3;

[0019] The concentration liquid circulating pool 3 is provided with a third liquid outlet 3-3 at the lower portion of one side, the third liquid outlet 3-3 is communicated with a first liquid inlet 1-3 provided at the top of the concentration tower 1 through a concentration liquid circulating pump 4; the concentration liquid circulating pool 3 is provided with a fourth liquid inlet 3-1 at the middle upper portion of the pool edge height direction of the side where the concentration tower 1 is located, the fourth liquid inlet 3-1 is communicated with a first liquid outlet 1-4 provided at the bottom of the concentration tower 1 through a concentration tower slurry discharge valve 6; the concentration liquid circulating pool 3 is provided with a fifth liquid inlet 3-2 at the middle upper portion of the pool edge height direction of the side where the dilute tower 2 is located, and the fifth liquid inlet 3-2 is communicated with a second liquid outlet 2-2 provided at the bottom of the dilute tower 2 through a dilute tower liquid discharge pump 5.

[0020] The inside of the concentration tower 1 is provided with 1-2 layers of concentration tower desulfurization slurry spraying layers 1-5 at the upper portion, and the concentration tower desulfurization slurry spraying layers 1-5 are not higher than the first liquid inlet 1-3.

[0021] The bottom of the one side of the dilute tower 2 is externally connected with a dilute tower slurry oxidation fan 10 through a dilute liquid oxidation air pipe 2-7; the other side of the dilute tower 2 is also provided with a fresh slurry inlet 2-8 at the bottom, and the fresh slurry inlet 2-8 is externally connected with a lime slurry pump 8.

[0022] The inside of the dilute tower 2 is respectively provided with 3-4 layers of dilute tower desulfurization slurry spraying layers 2-4 and 1-3 layers of ridge type high-efficiency mist eliminators 2-5 at the upper portion, the ridge type high-efficiency mist eliminators 2-5 are located at the upper portion of the dilute tower desulfurization slurry spraying layers 2-4, the distance between the ridge type high-efficiency mist eliminator 2-5 located at the bottom layer and the dilute tower desulfurization slurry spraying layer 2-4 located at the top layer is 1.5-2.0 m, and the dilute tower desulfurization slurry spraying layers 2-4 are not higher than the third liquid inlet 2-3.

[0023] The dilute tower circulating pump 9 is set to be multiple according to the initial concentration of flue gas SO2.

[0024] The concentration liquid circulating pool 3 is also provided with a concentration tower gypsum discharge outlet 3-4, the concentration tower gypsum discharge outlet 3-4 is externally connected with a dehydration system through a concentration tower gypsum discharge pump 7, and the concentration liquid circulating pool 3 is externally connected with a concentration tower slurry oxidation fan 11 through a concentration liquid oxidation air pipe 3-5.

[0025] The concentration tower 1 and the dilution tower 2 are arranged in multiple groups, each group comprising one concentration tower 1 and one dilution tower 2; the first liquid outlets 1-4 of all the concentration towers 1 are communicated with the fourth liquid inlets 3-1 of the concentrated liquid circulating pool 3, and the first liquid inlets 1-3 of all the concentration towers 1 are communicated with the third liquid outlets 3-3 of the concentrated liquid circulating pool 3; the second liquid outlets 2-2 of all the dilution towers 2 are communicated with the fifth liquid inlets 3-2 of the same concentrated liquid circulating pool 3, and the concentrated liquid circulating pool 3 is connected with a dewatering system through a concentrated gypsum discharge pump 7.

[0026] Compared with the prior art, the utility model has the advantages that:

[0027] 1. The desulfurized slurry is discharged without difference: all the desulfurization towers of multiple boilers can share one set of dewatering system, all the dilution towers 2 can discharge liquid to the concentrated liquid circulating pool 3 at the same time, all the concentration towers 1 are circulated outside the tower, the slurry of the concentration tower is discharged to the concentrated liquid circulating pool 3 at the same time, and then is sent to the pre-desulfurization concentration tower 1 through the concentrated liquid circulating pump 4 for desulfurization circulation, and the gypsum is discharged from the concentrated liquid circulating pool 3 to the dewatering system for dewatering; the multiple desulfurization towers of the whole plant can simultaneously discharge gypsum without difference.

[0028] 2. The emission of flue gas SO2 and particulate matter is long-term stable and reaches the standard: the hot flue gas and the circulating slurry of the concentration tower 1 are countercurrently contacted, part of SO2 is washed and removed, and the water in the slurry is evaporated to concentrate the liquid. After the water vapor in the flue gas after pre-desulfurization of the concentration tower 1 reaches the saturated state, the flue gas enters the dilution tower 2 with high PH value (6.5-7.0) and low slurry density for further fine desulfurization, and after SO2 reaches the ultra-low emission standard, the flue gas is defogged by the roof ridge type high-efficiency defogger 2-5 at the top of the dilution tower to reduce the liquid drop content in the flue gas to 25mg / m 3 The flue gas is discharged into the chimney, and the SO2 and particulate matter in the flue gas can long-term stably reach the ultra-low or ultra-clean emission index.

[0029] 3. The problem of difficult control of material balance of the desulfurization tower is solved: after concentration and dilution, the dilution tower 2 can reliably maintain the high PH value and low slurry density required for ultra-low emission, the concentration tower 1 can concentrate and fully reuse the discharge liquid of the dilution tower, and the problems of high density in the tower, insufficient reaction of the desulfurization agent, difficulty in dewatering of gypsum, and out-of-control material balance in the traditional single-tower desulfurization process are avoided.

[0030] 4. The problem of excessive consumption of desulfurization agent is solved: the discharge liquid of the dilution tower after fine desulfurization has high PH value (6.5-7.0) and contains a large amount of unreacted desulfurization agent (including shielded desulfurization agent), which is continuously circulated and reused in the concentration tower 1, and is unshielded in the concentrated liquid with low PH value (4.5-5.4), so that the desulfurization agent is fully utilized, and the consumption of the desulfurization agent is greatly reduced.

[0031] 5. Solve the problem of the influence of the desulfurization reaction shielding area on the boiler operation and environmental protection emissions: In the previous single-tower desulfurization process, if the desulfurizer desulfurization reaction shielding area occurs inside the single tower, the solution adopted is to stop the desulfurization slurry supply, even stop the boiler, add fresh slurry, and reduce the slurry PH value in the single tower to 4.5, at which time the SO2 emission value will decrease significantly. The scheme of the present application can discharge the slurry in the tower to the thick liquid circulating pool 3, and will not affect the control of the shutdown and desulfurization emission, and realize the long-term stable standard of SO2 and particulate matter at the outlet of the desulfurization tower.

[0032] In summary, the present application washes and elutes SO2 in the boiler flue gas through the two-stage desulfurization tower of the thick tower 1 and the thin tower 2 in series, and the technology of one thick liquid circulating pool 3 shared by multiple boilers, in operation, the thick tower slurry is kept at high concentration and low PH value, and the thin tower slurry is kept at low concentration and high PH value, the thick and thin separation state, which makes the desulfurization efficient grading from the source, and reduces the concentration of particulate matter in the desulfurization tower, has the advantages of high desulfurization efficiency, low desulfurizer consumption, long-term stable standard of SO2 and particulate matter emission indicators at the outlet of the desulfurization tower, and simultaneous desulfurization of multiple boilers without difference. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a system structure schematic diagram of the present application.

[0034] Among them, 1, thick tower; 1-1, first flue gas inlet; 1-2, first flue gas outlet; 1-3, first liquid inlet; 1-4, first liquid outlet; 1-5, thick tower desulfurization slurry spraying layer; 2, thin tower; 2-1, second flue gas inlet; 2-2, second liquid outlet; 2-3, third liquid inlet; 2-4, thin tower desulfurization slurry spraying layer; 2-5, ridge type high efficiency mist eliminator; 2-6, slurry circulating outlet; 2-7, thin liquid oxidation air pipe; 2-8, fresh slurry inlet; 3, thick liquid circulating pool; 3-1, fourth liquid inlet; 3-2, fifth liquid inlet; 3-3, third liquid outlet; 3-4, thick tower gypsum outlet; 3-5, thick liquid oxidation air pipe; 4, thick liquid circulating pump; 5, thin tower liquid pump; 6, thick tower slurry discharge valve; 7, thick tower gypsum discharge pump; 8, lime slurry pump; 9, thin tower circulating pump; 10, thin tower slurry oxidation air blower; 11, thick tower slurry oxidation air blower. DETAILED DESCRIPTION

[0035] The technical scheme adopted by the present application will be further described below in combination with the drawings and specific embodiments.

[0036] As shown in Figure 1 A thick and thin separation ultra-low emission desulfurization system, comprising a thick tower 1, a thin tower 2, a thick liquid circulating pool 3 and a thick liquid circulating pump 4 which are in communication with each other;

[0037] The concentration tower 1 is used for first-stage removal of SO2 in the boiler flue gas, and the removal rate is about 60%, and part of the particulate matters in the boiler flue gas is washed out.

[0038] The first flue gas inlet 1-1 is arranged in the middle and lower part of one side of the concentration tower 1, the first liquid inlet 1-3 is arranged at the top of the concentration tower 1, the boiler flue gas enters the concentration tower 1 through the first flue gas inlet 1-1, and the thick liquid flowing out of the thick liquid circulating pool 3 enters the concentration tower 1 through the first liquid inlet 1-3 to be contacted, so that the SO2 in the boiler flue gas is removed in the first stage, the first flue gas outlet 1-2 is arranged at the other side of the concentration tower 1, the flue gas output by the concentration tower 1 enters the dilution tower 2 through the first flue gas outlet 1-2, and the first liquid outlet 1-4 is arranged at the bottom of the concentration tower 1 and is communicated with the thick liquid circulating pool 3.

[0039] The concentration tower 1 is used for first-stage removal of SO2 in the boiler flue gas, and the removal rate is about 60%, and part of the particulate matters in the boiler flue gas is washed out.

[0040] The dilution tower 2 is used for second-stage removal of SO2 in the flue gas output by the concentration tower 1.

[0041] The dilution tower 2 is arranged after the concentration tower 1, and the flue gas discharged from the concentration tower 1 is subjected to desulfurization and dust removal again, the removal rate of SO2 and particulate matters in the flue gas from the concentration tower 1 can reach more than 98%, and the ultrafine particulate matters in the flue gas and the secondary dust generated in the desulfurization process can be washed out, so that the flue gas reaches the ultra-clean emission index, that is, less than 5mg / m 3 .

[0042] The second flue gas inlet 2-1 is arranged at one side of the dilution tower 2 and is communicated with the first flue gas outlet 1-2 of the concentration tower 1, the flue gas output by the concentration tower 1 enters the dilution tower 2 through the second flue gas inlet 2-1, the dilution tower 2 removes SO2 in the flue gas in the second stage, the third liquid inlet 2-3 is arranged at the other side and upper part of the dilution tower 2, the slurry circulating outlet 2-6 is arranged at the other side and lower part of the dilution tower 2, the slurry circulating outlet 2-6 is communicated with the third liquid inlet 2-3 of the dilution tower 2 through the dilution tower circulating pump 9, the second liquid outlet 2-2 is arranged at the bottom of the dilution tower 2 and is communicated with the thick liquid circulating pool 3.

[0043] The dilution tower circulating pump 9 draws the slurry from the bottom of the dilution tower 2 and sprays the slurry into the dilution tower desulfurization slurry spraying layer 2-4 at the top of the dilution tower 2 through the third liquid inlet 2-3 and the slurry circulating outlet 2-6, and the dilution tower slurry oxidation fan 10 draws air from the atmosphere and blows the air into the bottom of the dilution tower 2 through the dilution liquid oxidation air pipe 2-7.

[0044] The dilution tower circulating pump 9 can be set to be multiple according to the initial concentration of SO2 in the flue gas.

[0045] The bottom of one side of the dilute tower 2 is externally connected with a dilute tower slurry oxidizing fan 10 through a dilute liquid oxidizing air pipe 2-7; the bottom of the other side of the dilute tower 2 is also provided with a fresh slurry inlet 2-8, and the fresh slurry inlet 2-8 is externally connected with a lime slurry pump 8.

[0046] The upper part of the inside of the dilute tower 2 is respectively provided with 3-4 layers of dilute tower desulfurization slurry spraying layers 2-4 and 1-3 layers of ridge type high efficiency mist eliminators 2-5, the ridge type high efficiency mist eliminators 2-5 are located at the upper part of the dilute tower desulfurization slurry spraying layers 2-4, and the distance between the ridge type high efficiency mist eliminator 2-5 located at the bottom layer and the dilute tower desulfurization slurry spraying layer 2-4 located at the uppermost layer is 1.5-2.0 m; the dilute tower desulfurization slurry spraying layer 2-4 is not higher than the third liquid inlet 2-3.

[0047] The concentrated liquid circulating pool 3 is used for storing the concentrated liquid discharged after the concentrated tower 1 is used to remove SO2 in the boiler flue gas in the first stage and the dilute liquid discharged after the dilute tower 2 is used to remove SO2 in the flue gas output by the concentrated tower 1 in the second stage; meanwhile, according to the PH value of the mixed concentrated liquid and dilute liquid after use in the concentrated liquid circulating pool 3, new desulfurization lime slurry is added as needed, fully mixed, and mixed desulfurization slurry, i.e. "desulfurization concentrated liquid" is formed.

[0048] The lower part of one side of the concentrated liquid circulating pool 3 is provided with a third liquid outlet 3-3, the third liquid outlet 3-3 is connected with the first liquid inlet 1-3 provided at the top of the concentrated tower 1 through a concentrated liquid circulating pump 4; the middle upper part of the pool edge height direction of the concentrated liquid circulating pool 3 at the position where the concentrated tower 1 is located is provided with a fourth liquid inlet 3-1, the fourth liquid inlet 3-1 is connected with the first liquid outlet 1-4 provided at the bottom of the concentrated tower 1 through a concentrated tower slurry discharge valve 6; the middle upper part of the pool edge height direction of the concentrated liquid circulating pool 3 at the position where the dilute tower 2 is located is provided with a fifth liquid inlet 3-2, and the fifth liquid inlet 3-2 is connected with the second liquid outlet 2-2 provided at the bottom of the dilute tower 2 through a dilute tower liquid discharge pump 5.

[0049] The concentrated tower gypsum discharge outlet 3-4 is further provided on the concentrated liquid circulating pool 3, the concentrated tower gypsum discharge outlet 3-4 is externally connected with a dewatering system through a concentrated tower gypsum discharge pump 7, and the concentrated liquid circulating pool 3 is externally connected with a concentrated tower slurry oxidizing fan 11 through a concentrated liquid oxidizing air pipe 3-5; the concentrated tower slurry oxidizing fan 11 extracts air from the atmosphere and blows the air into the concentrated liquid circulating pool 3 through the concentrated liquid oxidizing air pipe 3-5.

[0050] The concentrated liquid circulating pool 3 is used for storing the desulfurization waste liquid discharged from the desulfurization tower 2 after use, also called "light liquid", and supplementing part of fresh desulfurization lime slurry to the concentrated liquid circulating pool 3 as needed, and after the light liquid is fully mixed with the fresh desulfurization lime slurry, the mixed desulfurization slurry in the concentrated liquid circulating pool 3 is transported to the concentrated tower 1 by the concentrated liquid circulating pump 4, and the concentrated liquid used by the concentrated tower 1 is returned to the concentrated liquid circulating pool 3 again through the first liquid outlet 1-4 at the bottom of the concentrated tower 1 and the fourth liquid inlet 3-1 of the concentrated liquid circulating pool 3, and the use is repeated in this way, and no waste liquid is discharged.

[0051] The concentrated liquid circulating pump 4 is used for circulating and transporting the desulfurization concentrated liquid in the concentrated liquid circulating pool 3 to the concentrated tower 1.

[0052] The concentrated tower 1 and the desulfurization tower 2 are arranged in multiple groups, each group comprising one concentrated tower 1 and one desulfurization tower 2; the first liquid outlets 1-4 of all the concentrated towers 1 are communicated with the fourth liquid inlets 3-1 of the concentrated liquid circulating pool 3, and the first liquid inlets 1-3 of all the concentrated towers 1 are communicated with the third liquid outlets 3-3 of the concentrated liquid circulating pool 3; the second liquid outlets 2-2 of all the desulfurization towers 2 are communicated with the fifth liquid inlets 3-2 of the same concentrated liquid circulating pool 3, and the desulfurization slurry is discharged from the concentrated tower 1 to the dewatering system through the concentrated liquid circulating pool 3 and the gypsum slurry discharge pump 7.

[0053] A plurality of boilers share one set of desulfurization system, and in one set of desulfurization system, a corresponding number of concentrated towers 1 and desulfurization towers 2 can be arranged according to the number of boilers, one concentrated tower 1 corresponds to one desulfurization tower 2, the plurality of concentrated towers 1 are in parallel relationship, the plurality of desulfurization towers 2 are also in parallel relationship, and there is no mutual connection, all the desulfurization liquid of the desulfurization towers enters the same concentrated liquid circulating pool 3, and all the concentrated liquid of the concentrated towers also enters the same concentrated liquid circulating pool 3, and the gypsum slurry is discharged from the concentrated liquid circulating pool 3 to the common gypsum dewatering system for dewatering by the gypsum slurry discharge pump 7.

[0054] The concentrated tower 1 and the desulfurization tower 2 can realize that SO2 and particulate matters in flue gas of various boilers are stably and long-termly up to the national ultra-low or ultra-clean emission standard.

[0055] The desulfurization tower 2 can be made into a smoke tower integrated structure with a chimney, or can be made into a separate form.

[0056] The working principle of the utility model is as follows:

[0057] The boiler flue gas enters the concentration tower 1 through the first flue gas inlet 1-1 and the desulfurization slurry spraying layer 1-5, and is in countercurrent contact with the desulfurization concentrated solution which enters the first liquid inlet 1-3 of the concentration tower 1 through the third liquid outlet 3-3 and the concentration solution circulating pump 4, so that the SO2 in the boiler flue gas is removed in the first stage, the SO2 content of the flue gas is reduced, the water vapor is saturated, and the desulfurizer in the concentrated solution which is not fully reacted is reused, and the concentrated solution is concentrated and enters the concentration solution circulating pool 3 through the fourth liquid inlet 3-1, and is oxidized by the concentration tower slurry oxidizing fan 11; the PH value of the concentrated solution in the concentration solution circulating pool 3 is controlled at 4.5-5.4, and the density of the concentrated solution is controlled at 1.3t / m 3 When the density exceeds the standard, the concentration tower gypsum discharge pump 7 discharges the concentrated solution in the concentration solution circulating pool 3 to the dehydration system for dehydration, and the concentrated solution of the concentration tower 1 enters the fourth liquid inlet 3-1 of the concentration solution circulating pool 3 through the first liquid outlet 1-4 and the concentration tower slurry discharge valve 6, and is reused.

[0058] The flue gas after the first stage SO2 removal is discharged from the first flue gas outlet 1-2 of the concentration tower 1, enters the dilution tower 2 through the second flue gas inlet 2-1, and is in countercurrent contact with the dilute solution which is sprayed from the dilute solution spraying layer 2-4 of the dilution tower 2 through the third liquid inlet 2-3 of the dilution tower 2 and the dilution tower circulating pump 9 at the bottom of the dilution tower 2, so that the SO2 is removed in the second stage, and after most of the liquid droplets carried by the flue gas are removed by the ridge type high efficiency mist eliminator 2-5 at the top of the dilution tower, the flue gas enters the chimney and is discharged into the atmosphere; the dilute solution absorbs SO2 in the flue gas to produce CaSO3, and the dilution tower slurry oxidation fan 10 draws air through the dilute solution oxidation air pipe 2-7 to blow the dilution tower slurry to oxidize CaSO3 in the dilution tower slurry into gypsum (CaSO3·2H2O); the PH value of the circulating slurry at the bottom of the dilution tower 2 is controlled at 6.5-7.0, and the density of the circulating slurry is controlled at 1.15t / m 3 When the density exceeds the standard, the concentration tower gypsum discharge pump 7 discharges the concentrated solution in the concentration solution circulating pool 3 to the dehydration system for dehydration, and the concentrated solution of the concentration tower 1 enters the fourth liquid inlet 3-1 of the concentration solution circulating pool 3 through the first liquid outlet 1-4 and the concentration tower slurry discharge valve 6, and is reused. 3 When the density exceeds the standard, the concentration tower gypsum discharge pump 7 discharges the concentrated solution in the concentration solution circulating pool 3 to the dehydration system for dehydration, and the concentrated solution of the concentration tower 1 enters the fourth liquid inlet 3-1 of the concentration solution circulating pool 3 through the first liquid outlet 1-4 and the concentration tower slurry discharge valve 6, and is reused.

[0059] The concentration solution circulating pool 3 adds new desulfurization lime slurry according to the PH value of the mixed concentrated solution and dilute solution, mixes thoroughly to form mixed desulfurization slurry, that is, "desulfurization concentrated solution", and enters the concentration tower 1 again to remove SO2 in the boiler flue gas in the first stage.

[0060] The 2-4 desulfurizing slurry spraying layers in the lean tower are arranged in 2-4 layers in the lean tower according to the sulfur content in the flue gas, the slurry sprayed from the nozzles is in umbrella-shaped atomized state, can effectively contact with the flue gas, and the atomized desulfurizing slurry film formed by the 2-4 desulfurizing slurry spraying layers in the lean tower can ensure that 100% of the flue gas passing through the lean tower 2 contacts with the desulfurizing slurry, so that high-efficiency desulfurization and dust removal effects are achieved. The lean tower slurry oxidizing fan 10 blows high-pressure air to the bottom of the slurry in the lean tower 2, so that the desulfurizing slurry in the lean tower 2 is subjected to oxidation reaction, (CaSO3·2H2O) is generated, the gypsum is quickly removed, and the density in the lean tower is controlled to be less than or equal to 1.15 t / m3.

[0061] The rich tower 1 and the lean tower 2 are connected through a flue, the flue gas from the boiler passes through the bag-type dust collector, is subjected to pre-desulfurization in the rich tower 1, then enters the lean tower 2 for fine desulfurization, and is discharged to the atmosphere through the chimney after the fine desulfurization.

[0062] A rich tower 1 is arranged at the outlet of each boiler induced draft fan, 1 layer of rich tower desulfurizing slurry spraying layer 1-5 is arranged in the rich tower 1, a first liquid outlet 1-4 is arranged at the bottom, and the desulfurizing slurry is circulated by the rich liquid circulating pump 4, so that the flue gas is subjected to countercurrent elution pre-desulfurization, and then is discharged into the rich liquid circulating pool 3 from the bottom of the tower.

[0063] The main chemical reactions occurring in the rich tower 1 are as follows:

[0064] Desulfurization process:

[0065] SO2+H2O→HSO3 - +H +

[0066] Ca(OH)2+2HSO3 - +2H + →Ca(HSO3)2+2H2O

[0067] CaSO3·1 / 2H2O+SO2+1 / 2H2O→Ca(HSO3)2

[0068] Oxidation process:

[0069] 2CaSO3·1 / 2H2O+O2+3H2O→2CaSO4·2H2O

[0070] Ca(HSO3)2+O2+2H2O→CaSO4·2H2O+H2SO4

[0071] The pH value of the rich tower is relatively low (4.5-5.4), in such an environment, the concentrations of H + and HSO3 - are much greater than that of SO3 2- , and HSO3 - is more easily oxidized to SO4 2- .

[0072] The thick liquid circulating pool 3 is provided with a thick liquid oxidation air pipe 3-5, the thick liquid is oxidized, after the gypsum is crystallized and precipitated, the thick liquid is sent to a dehydration system by a thick tower gypsum discharge pump 7 for dehydration, and the filtrate returns to the thick liquid circulating pool 3 for recycling.

[0073] A plurality of industrial boilers share one set of dehydration and pulping system and one discharge port, and the thick and thin separation ultra-low emission desulfurization system comprises a front slurry concentration pre-desulfurization thick tower 1, a matched thick liquid circulating pool 3, a thin tower 2 provided with a high-efficiency demister, a common gypsum dehydration system and a slurry preparation system.

[0074] The thick and thin separation ultra-low emission desulfurization system is suitable for efficient removal of SO2 and ultra-fine particulate matters in various flue gases, and the system process idea, process equipment composition and related parameters covered by the utility model belong to the protection range of the utility model.

Claims

1. A concentrated-desalination separation ultra-low emission desulfurization system, characterized in that, It includes an interconnected concentration tower (1), a dilute tower (2), a concentrate circulation tank (3), and a concentrate circulation pump (4); The concentration tower (1) is used for the first-stage removal of SO2 from boiler flue gas; The desalination tower (2) is used for the second-stage removal of SO2 from the flue gas output from the concentration tower (1); The concentrated liquid circulation tank (3) is used to store the concentrated liquid discharged after the concentrated tower (1) removes SO2 from the boiler flue gas in the first stage, and the desalinated liquid discharged after the desalinated tower (2) removes SO2 from the flue gas output by the concentrated tower (1) in the second stage; at the same time, according to the pH value of the concentrated liquid and desalinated liquid after mixing in the concentrated liquid circulation tank (3), new desulfurization lime slurry is added as needed and fully mixed to form a mixed desulfurization slurry, namely "desulfurization concentrated liquid"; The concentrate circulation pump (4) is used to circulate and transport the mixed slurry in the concentrate circulation tank (3) to the concentrate tower (1).

2. The ultra-low emission desulfurization system for concentration-desalination separation according to claim 1, characterized in that, The concentration tower (1) and distillation tower (2) are configured in multiple groups, each group including one concentration tower (1) and one distillation tower (2); All concentration towers (1) are connected to the concentration circulation tank (3), and all dilute towers (2) are connected to the same concentration circulation tank (3). The gypsum discharge pump (7) of the concentration towers is connected to the external dehydration system through the concentration circulation tank (3).

3. A concentrated-desalination ultra-low emission desulfurization system according to claim 1 or 2, characterized in that, The concentration tower (1) has a first flue gas inlet (1-1) in the middle and lower part of one side, and a first liquid inlet (1-3) in the top of the concentration tower (1). The boiler flue gas enters the concentration tower (1) through the first flue gas inlet (1-1) and comes into contact with the concentrated liquid flowing out of the concentrated liquid circulation pool (3) through the first liquid inlet (1-3) to remove SO2 from the boiler flue gas in the first stage. The concentration tower (1) has a first flue gas outlet (1-2) in the other side, and the flue gas output from the concentration tower (1) enters the desalination tower (2) through the first flue gas outlet (1-2). The concentration tower (1) has a first liquid outlet (1-4) in the bottom, and the first liquid outlet (1-4) is connected to the concentrated liquid circulation pool (3). The distillation tower (2) has a second flue gas inlet (2-1) on one side that is connected to the first flue gas outlet (1-2) of the concentration tower (1). The flue gas output from the concentration tower (1) enters the distillation tower (2) through the second flue gas inlet (2-1). The distillation tower (2) removes SO2 from the flue gas in the second stage. The distillation tower (2) has a third liquid inlet (2-3) at the upper part of the other side and a slurry circulation outlet (2-6) at the lower part of the other side. The slurry circulation outlet (2-6) is connected to the third liquid inlet (2-3) of the distillation tower (2) through the distillation tower circulation pump (9). The distillation tower (2) has a second liquid outlet (2-2) at the bottom and is connected to the concentration circulation tank (3). The concentrated liquid circulation tank (3) has a third outlet (3-3) on the lower part of one side. The third outlet (3-3) is connected to the first inlet (1-3) at the top of the concentrated tower (1) through the concentrated liquid circulation pump (4). The concentrated liquid circulation tank (3) has a fourth inlet (3-1) at the middle and upper part of the pool side along the height direction on the side where the concentrated tower (1) is located. The fourth inlet (3-1) is connected to the first outlet (1-4) at the bottom of the concentrated tower (1) through the concentrated tower slurry discharge valve (6). The concentrated liquid circulation tank (3) has a fifth inlet (3-2) at the middle and upper part of the pool side along the height direction on the side where the dilute tower (2) is located. The fifth inlet (3-2) is connected to the second outlet (2-2) at the bottom of the dilute tower (2) through the dilute tower discharge pump (5).

4. The ultra-low emission desulfurization system for concentration-desalination separation according to claim 3, characterized in that, The upper part of the concentrator (1) is provided with 1 to 2 layers of concentrator desulfurization slurry spray layer (1-5), and the concentrator desulfurization slurry spray layer (1-5) is not higher than the first liquid inlet (1-3).

5. The ultra-low emission desulfurization system for concentration-desalination separation according to claim 3, characterized in that, The bottom of one side of the distillation tower (2) is connected to the distillation tower slurry oxidation fan (10) through the distillation slurry oxidation air pipe (2-7); the bottom of the other side of the distillation tower (2) is also provided with a fresh slurry inlet (2-8), and the fresh slurry inlet (2-8) is connected to a lime slurry pump (8).

6. The ultra-low emission desulfurization system for concentration-desalination separation according to claim 3, characterized in that, The upper part of the interior of the desulfurization tower (2) is provided with 3 to 4 layers of desulfurization slurry spraying layer (2-4) and 1 to 3 layers of ridge-type high-efficiency demisters (2-5). The ridge-type high-efficiency demisters (2-5) are located above the desulfurization slurry spraying layer (2-4). The distance between the bottom ridge-type high-efficiency demister (2-5) and the top desulfurization slurry spraying layer (2-4) is 1.5 to 2.0 m. The desulfurization slurry spraying layer (2-4) is not higher than the third liquid inlet (2-3).

7. The ultra-low emission desulfurization system for concentration-desalination separation according to claim 3, characterized in that, The distillation tower circulating pump (9) is configured in multiple ways according to the initial SO2 concentration in the flue gas.

8. The ultra-low emission desulfurization system for concentration-desalination separation according to claim 3, characterized in that, The concentrated liquid circulation tank (3) is also provided with a concentrated tower gypsum outlet (3-4). The concentrated tower gypsum outlet (3-4) is connected to the dewatering system through the concentrated tower gypsum discharge pump (7). The concentrated liquid circulation tank (3) is connected to the concentrated tower slurry oxidation blower (11) through the concentrated liquid oxidation air pipe (3-5).

9. The ultra-low emission desulfurization system for concentration-desalination separation according to claim 3, characterized in that, The first outlet (1-4) of all the concentration towers (1) is connected to the fourth inlet (3-1) of the concentration circulation tank (3), and the first inlet (1-3) of all the concentration towers (1) is connected to the third outlet (3-3) of the concentration circulation tank (3); the second outlet (2-2) of all the dilute towers (2) is connected to the fifth inlet (3-2) of the same concentration circulation tank (3), and the gypsum discharge pump (7) of the concentration towers is connected to the external dehydration system through the concentration circulation tank (3).

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