A flue gas desulfurization system

Abstract

The present invention relates to the technical field of flue gas desulfurization, and discloses a flue gas desulfurization system, including a tower body, a liquid storage chamber for storing limestone solution is provided at the bottom of the tower body, a flue gas inlet is provided at the side wall of the tower body, a first spray layer and a second spray layer are provided inside the tower body, an exhaust port is provided at the top of the tower body, and the first spray layer and the second spray layer are located between the flue gas inlet and the exhaust port, the first spray layer is used to spray calcium hydroxide solution, the second spray layer is connected to the liquid storage chamber, and the side wall of the liquid storage chamber is connected to an oxidation fan and a gypsum discharge assembly. The present invention arranges the first spray layer and the second spray layer inside the tower body, and the first spray layer is used to spray calcium hydroxide solution, and the second spray layer is connected to the liquid storage chamber, so that there is no emission of carbon dioxide in the entire desulfurization process, thereby achieving low carbon emissions in the absorption process and improving the flue gas treatment result.

Description

Technical Field

[0001] The invention relates to the technical field of flue gas desulfurization, and in particular to a flue gas desulfurization system. Background Art

[0002] The existing flue gas desulfurization projects of thermal power groups usually adopt the limestone-gypsum wet flue gas desulfurization process, and the desulfurization efficiency guarantee value of the designed desulfurization device is greater than 93%. One furnace and one tower system is adopted. The FGD device adopts wet forced oxidation and limestone-gypsum recovery process. However, the slurry used to remove SO2 is collected in the absorber slurry pool, and the absorber slurry pool is divided into an oxidation zone and a crystallization zone. In the upper oxidation zone, oxidizing air is blown in through a distribution system to generate gypsum in the slurry with a pH value of 4.5 to 5.5; in the crystallization zone, the gypsum seeds gradually increase and form larger crystals that are easy to dehydrate. New limestone slurry is also added to this area. The overall chemical reaction formula is: CaCO3+SO2+1 / 2O2+2H2O→CaSO4·2H2O+CO2. It can be seen from the chemical reaction process that CO2 will be generated in the process of removing SO2, which increases greenhouse gas emissions and the exhaust gas treatment results are not good. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a flue gas desulfurization system to avoid the generation of carbon dioxide during the desulfurization process and improve the flue gas treatment results.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A flue gas desulfurization system comprises a tower body, wherein a liquid storage chamber for storing a limestone solution is provided at the bottom of the tower body, a flue gas inlet is provided on the side wall of the tower body, a first spray layer and a second spray layer are provided inside the tower body, an exhaust port is provided on the top of the tower body, and the first spray layer and the second spray layer are located between the flue gas inlet and the exhaust port, the first spray layer is used for spraying a calcium hydroxide solution, the second spray layer is communicated with the liquid storage chamber, and an oxidation fan and a gypsum discharge assembly are connected to the side wall of the liquid storage chamber.

[0006] Preferably, the content of the calcium hydroxide solution is 18% to 25% of the total desulfurizing agent content, wherein the total desulfurizing agent content is the sum of the content of the calcium hydroxide solution and the content of the limestone solution.

[0007] Preferably, the first spray layer is located above the second spray layer, and the number of the first spray layer is one or two.

[0008] Preferably, a flushing layer is provided inside the tower body above the first spraying layer, the flushing layer is connected to flushing water via a flushing pipe, and a first electric valve is provided on the flushing pipe.

[0009] Preferably, a tray is provided inside the tower body, and the tray is located between the smoke inlet and the second spray layer.

[0010] Preferably, the first spray layer is connected to the calcium hydroxide solution through a first spray pipe.

[0011] Preferably, the second spray layer is connected to the liquid storage chamber through a second spray pipe, and the second spray pipe is provided with a circulation pump and a second electric valve.

[0012] Preferably, the gypsum discharge assembly comprises a discharge pipe, the discharge pipe is provided with a gypsum discharge pump, and the inlet and outlet of the gypsum discharge pump are both provided with a third electric valve.

[0013] Preferably, a plurality of discharge pipes are provided at the discharge end of the discharge pipe, and a fourth electric valve is provided on the discharge pipe.

[0014] Preferably, a plurality of air inlet branch pipes are evenly distributed on the side wall of the liquid storage chamber, and the plurality of air inlet branch pipes are connected to the oxidation fan through an air inlet main pipe.

[0015] Compared with the prior art, a flue gas desulfurization system according to an embodiment of the present invention has the following beneficial effects: by arranging a first spray layer and a second spray layer inside the tower body, and the first spray layer is used to spray the calcium hydroxide solution, and the second spray layer is connected to the liquid storage chamber, so that the calcium hydroxide solution replaces part of the limestone slurry for desulfurization during the desulfurization process, and there is no emission of carbon dioxide in the whole process, thereby achieving low carbon emission in the absorption process and improving the flue gas treatment result. The present invention has a simple structure, good use effect, and is easy to promote and use. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the flue gas desulfurization system of the present invention.

[0017] Among them: 1-tower body, 2-liquid storage chamber, 3-smoke inlet, 4-exhaust port, 5-first spray layer, 6-second spray layer, 7-oxidation fan, 8-flushing layer, 9-flushing pipe, 10-first electric valve, 11-tray, 12-first spray pipe, 13-second spray pipe, 14-circulation pump, 15-second electric valve, 16-discharge pipe, 17-gypsum discharge pump, 18-third electric valve, 19-discharge pipe, 20-fourth electric valve, 21-air inlet branch pipe, 22-air inlet main pipe, 23-stirring device. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0019] like Figure 1 As shown, a flue gas desulfurization system of a preferred embodiment of the present invention comprises a tower body 1, a liquid storage chamber 2 for storing limestone solution is provided at the bottom of the tower body 1, a flue gas inlet 3 is provided on the side wall of the tower body 1, a first spray layer 5 and a second spray layer 6 are provided inside the tower body 1, and an exhaust port 4 is provided on the top of the tower body 1 for discharging clean flue gas after desulfurization. The first spray layer 5 and the second spray layer 6 are located between the flue gas inlet 3 and the exhaust port 4, the first spray layer 5 is used to spray calcium hydroxide solution, the second spray layer 6 is connected to the liquid storage chamber 2, and the side wall of the liquid storage chamber 2 is connected to an oxidation fan 7 and a gypsum discharge assembly, and the oxidation fan 7 is used to transport oxygen for oxidation of chemical reactions in the entire desulfurization process.

[0020] The flue gas desulfurization system based on the above technical features is provided with a first spray layer 5 and a second spray layer 6 inside the tower body 1, and the first spray layer 5 is used to spray the calcium hydroxide solution, and the second spray layer 6 is connected to the liquid storage chamber 2, so that the calcium hydroxide solution replaces part of the limestone slurry for desulfurization during the desulfurization process, and there is no emission of carbon dioxide in the whole process, thereby achieving low carbon emission in the absorption process and improving the flue gas treatment result. The present invention has a simple structure, good use effect, and is easy to promote and use.

[0021] The calcium hydroxide solution used in the present invention mainly comprises ultrafine Ca(OH)2, with a calcium base as a substrate, part of alkaline metals and carbonate ions as auxiliary materials, and a variety of functional components activated and modified to achieve strong alkaline properties, efficiently absorb sulfur dioxide, and have the ability to capture metal ions.

[0022] Its main indicators are:

[0023] Appearance: milky white liquid

[0024] Acid insoluble matter ≤ 0.3%;

[0025] pH ≥13.

[0026] The chemical reaction that occurs in the absorption process of the present invention is as follows:

[0027] Ca(OH)2+SO2=CaSO3·12H2O+12H2O

[0028] Neutralization process:

[0029] CaSO3·12H2O+SO2+12H2O=Ca(HSO3)2

[0030] Ca(HSO3)2+Ca(OH)2=2CaSO3·H2O

[0031] Oxidation process:

[0032] 2CaSO3·H2O+O2=2CaSO4·2H2O.

[0033] The entire process has no CO2 emissions, achieving low carbon emissions during the absorption process.

[0034] In this embodiment, the content of the calcium hydroxide solution is 18% to 25% of the total desulfurizer content, wherein the total desulfurizer content is the sum of the content of the calcium hydroxide solution and the content of the limestone solution, so as to keep the pH value of the absorber slurry stable at 5.3 to 5.7, and achieve the best desulfurization effect. In order to facilitate the control of the content of calcium hydroxide, the second spray layer 6 is connected to the liquid storage chamber 2 through the second spray pipe 13, and the second spray pipe 13 is provided with a circulation pump 14 and a second electric valve 15, and the second electric valve 15 can control the amount of limestone solution. The first spray layer 5 is connected to the calcium hydroxide solution through the first spray pipe 12. A regulating valve can be set on the first spray pipe 12 for easy control. Of course, since the calcium hydroxide solution is delivered separately, its mass fraction can also be controlled by directly controlling the delivery amount of calcium hydroxide.

[0035] The addition of the new desulfurization absorbent Ca(OH)2 produces the following technical features:

[0036] (1) The new desulfurization absorbent can greatly improve the desulfurization efficiency of the absorber, achieve near-zero SO2 emissions from the absorber, and help reduce the total SO2 emissions. Power plant tests show that at 600MW full load and design conditions, the desulfurization efficiency of the absorber reaches 99.86%. The net SO2 concentration of flue gas desulfurized with limestone slurry alone is 32mg / m 3 After adding the new synergist, it can be reduced to at least 22mg / m 3 .

[0037] (2) The new desulfurization absorbent has a fast reaction time for absorbing SO2. After use, it can enrich the means of regulating the outlet SO2 emission concentration and achieve operating condition optimization. Power plant tests show that the outlet SO2 concentration can be significantly reduced in about three minutes after the addition of the new desulfurization absorbent. This can reduce the time when the outlet SO2 concentration exceeds the standard during the load increase stage, when the sulfur content suddenly changes, and when the absorber slurry is "poisoned", thereby reducing the pressure on operating personnel.

[0038] (3) The new desulfurization absorbent absorbs SO2, which can effectively increase the maximum desulfurization output, expand the adaptability of the desulfurization system to high-sulfur coal, and facilitate coal procurement and save coal costs. Power plant tests show that when about 20% of the new enhancer is added at full load, the SO2 concentration in the original flue gas reaches 3300mg / m 3 When the SO2 concentration in the chimney can be controlled at 35mg / m 3Below, the ultra-low emission requirements are met. At this time, the SO2 concentration in the original flue gas is the design value of 2200mg / m 3 1.5 times of.

[0039] (4) The new desulfurization absorbent has a certain energy-saving effect after use. Compared with the original limestone slurry desulfurization, the addition of the new enhancer under the load of 600MW and 420MW in the power plant can reduce the operation of a slurry circulation pump, reduce the resistance of the desulfurization device, and significantly reduce the energy consumption of the induced draft fan, thus achieving an energy-saving effect.

[0040] (5) The addition of new desulfurization absorbent can reduce CO2 emissions. Taking full load and design conditions as an example, if 15% of new desulfurization absorbent is added, the CO2 emissions of two 600MW units in the power plant can be reduced by 12,289.2 tons in one year.

[0041] (6) The addition of new desulfurization absorbent has a significant improvement on the quality of gypsum.

[0042] In this embodiment, the first spray layer 5 is located above the second spray layer 6, and the number of the first spray layer 5 is one or two layers, and the specific number can be determined according to actual conditions. At the same time, a flushing layer 8 is provided inside the tower body 1 above the first spray layer 5, and the flushing layer 8 is connected to flushing water through a flushing pipe 9. The flushing pipe 9 is provided with a first electric valve 10, and the flushing of the system is controlled by the first electric valve 10. A tray 11 is also provided inside the tower body 1, and the tray 11 is located between the smoke inlet 3 and the second spray layer 6.

[0043] In this embodiment, the gypsum discharge assembly includes a discharge pipe 16, on which a gypsum discharge pump 17 is provided, and the inlet and outlet of the gypsum discharge pump 17 are both provided with a third electric valve 18 to discharge the gypsum. A plurality of discharge pipes 19 are provided at the discharge end of the discharge pipe 16, on which a fourth electric valve 20 is provided, and the plurality of discharge pipes 19 are all controlled by the fourth electric valve 20, so that each of the discharge pipes 19 can discharge the gypsum separately, or discharge the gypsum simultaneously, so as to facilitate the subsequent collection of the gypsum.

[0044] In this embodiment, the side wall of the liquid storage chamber 2 is evenly distributed with a plurality of air inlet branch pipes 21, and the plurality of air inlet branch pipes 21 are connected to the oxidation fan 7 through an air inlet main pipe 22. Since oxygen is required for oxidation during the entire desulfurization process, by evenly distributing a plurality of air inlet branch pipes 21 on the side wall of the liquid storage chamber 2, sufficient and uniform oxygen inside the liquid storage chamber 2 is ensured, thereby improving the desulfurization effect. At the same time, in order to further improve the desulfurization effect, a stirring device 23 is provided inside the liquid storage chamber 2.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A flue gas desulfurization system, characterized in that: It comprises a tower body, wherein a liquid storage cavity for storing limestone solution is provided at the bottom of the tower body, a smoke inlet is provided at the side wall of the tower body, a first spray layer and a second spray layer are provided inside the tower body, an exhaust port is provided at the top of the tower body, and the first spray layer and the second spray layer are located between the smoke inlet and the exhaust port, the first spray layer is used to spray calcium hydroxide solution, the second spray layer is communicated with the liquid storage cavity, and an oxidation fan and a gypsum discharge assembly are connected to the side wall of the liquid storage cavity; The first spray layer is connected to the calcium hydroxide solution through a first spray pipe, and a regulating valve is provided on the first spray pipe; The second spray layer is connected to the liquid storage chamber through a second spray pipe, and a circulation pump and a second electric valve are provided on the second spray pipe.

2. The flue gas desulfurization system according to claim 1, characterized in that: The content of the calcium hydroxide solution is 18% to 25% of the total desulfurizing agent content, wherein the total desulfurizing agent content is the sum of the content of the calcium hydroxide solution and the content of the limestone solution.

3. The flue gas desulfurization system according to claim 1, characterized in that: The first spray layer is located above the second spray layer, and the number of the first spray layer is one or two.

4. The flue gas desulfurization system according to claim 3, characterized in that: A flushing layer is provided inside the tower body above the first spraying layer. The flushing layer is connected to flushing water via a flushing pipe. A first electric valve is provided on the flushing pipe.

5. The flue gas desulfurization system according to claim 3, characterized in that: A tray is provided inside the tower body, and the tray is located between the smoke inlet and the second spray layer.

6. The flue gas desulfurization system according to claim 1, characterized in that: The gypsum discharge assembly comprises a discharge pipe, on which a gypsum discharge pump is arranged, and the inlet and outlet of the gypsum discharge pump are both provided with a third electric valve.

7. The flue gas desulfurization system according to claim 6, characterized in that: A plurality of discharge pipes are provided at the discharge end of the discharge pipe, and a fourth electric valve is provided on the discharge pipe.

8. The flue gas desulfurization system according to claim 1, characterized in that: A plurality of air inlet branch pipes are evenly distributed on the side wall of the liquid storage cavity, and the plurality of air inlet branch pipes are connected with the oxidation fan through an air inlet main pipe.

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