A compound desulfurizer for biogas complex iron wet desulfurization and a desulfurization method thereof

Abstract

The application discloses a kind of for marsh gas complex iron wet desulfurization, by ethylenediamine tetraacetic acid disodium, N-hydroxyethyl ethylenediamine triacid trisodium, ferric sulfate and 7 water ferrous sulfate composition. The desulfurization method using above-mentioned compound desulfurizer is, into desulfurization liquid regenerator, then by poor liquid pump, and desulfurization liquid is pumped to desulfurization sprayer and is sprayed, and marsh gas is inputted from marsh gas input pipe into desulfurization spray tower, and is outputted from marsh gas output pipe after being sprayed and desulfurized by desulfurization liquid, and the desulfurization liquid that is sprayed is pumped into regenerative sprayer by rich liquid pump, and is oxidized and regenerated with the air that is sprayed by aeration disc in desulfurization liquid regenerator, and the waste gas generated in desulfurization liquid regenerator is discharged after being purified by waste gas purification equipment, and the desulfurization liquid containing precipitated impurities in the bottom of desulfurization liquid regenerator is pumped into plate-and-frame filter press by pressure filtration pump and is filtered, and the filtered desulfurization liquid reenters desulfurization liquid regenerator.The application can improve the deficiency of prior art, and reduce ferrous sulfide precipitation.

Description

Technical Field

[0001] This invention relates to the field of biogas desulfurization technology, and in particular to a compound desulfurizing agent for wet desulfurization of biogas with complexed iron and its desulfurization method. Background Technology

[0002] Industrial and agricultural production processes generate large amounts of wastewater. While this wastewater undergoes anaerobic fermentation and purification, it also produces significant amounts of biogas. This results in the emission of large quantities of methane, a greenhouse gas that poses a significant threat to the atmospheric environment. Hydrogen sulfide in biogas is toxic and harmful; its release into the air pollutes the environment and endangers human and animal health. Many methods exist for removing hydrogen sulfide from biogas, among which the complexing iron method has been widely used in recent years. Compared to other desulfurization technologies, the complexing iron method offers advantages such as abundant and inexpensive iron resources, a high working sulfur capacity in the desulfurization liquid (significantly reducing liquid circulation volume and saving energy), and other benefits. However, after a period of use, a black precipitate of ferrous sulfide forms at the bottom of the desulfurization tower. This is mainly because under strongly alkaline conditions, the chelation concentration of iron ions in the complexing agent is low, weakening its shielding ability against iron ions, especially ferrous ions. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a compound desulfurizing agent and desulfurization method for wet desulfurization of biogas complexed iron, which can overcome the shortcomings of the prior art, reduce the precipitation of ferrous sulfide, and extend the continuous operation time of the equipment.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows.

[0005] A compound desulfurizing agent for wet desulfurization of biogas complexed iron is composed of disodium ethylenediaminetetraacetate, trisodium N-hydroxyethylethylenediaminetriacetate, ferric sulfate, and ferrous sulfate heptahydrate.

[0006] Preferably, the molar ratio of disodium ethylenediaminetetraacetate, trisodium N-hydroxyethylethylenediaminetriacetate, ferric sulfate, and ferrous sulfate heptahydrate is 3:2:6:2.

[0007] A desulfurization method for the above-mentioned compound desulfurizing agent for wet desulfurization of biogas complexed iron includes the following steps: The compound desulfurizing agent was mixed with water to prepare a desulfurization solution. The iron ion chelation concentration of the desulfurization solution was 0.1197 mol / L, and the pH value was 8.5. A desulfurization system is set up, including a desulfurization spray tower. The bottom of the desulfurization spray tower is connected to a biogas input pipe, and the top of the desulfurization spray tower is connected to a biogas output pipe. A desulfurization sprayer is fixed inside the desulfurization spray tower and is connected to the output end of a lean liquid pump. The bottom of the desulfurization spray tower is connected to the input end of a rich liquid pump, and the output end of the rich liquid pump is connected to a regeneration sprayer. The regeneration sprayer is fixed inside the desulfurization liquid regeneration tower, and the bottom of the desulfurization liquid regeneration tower is connected to the input end of the lean liquid pump. An aeration disc is installed below the regeneration sprayer and is connected to a Roots aerator. The bottom of the desulfurization liquid regeneration tower is connected to the input end of a filter press pump, and the output end of the filter press pump is connected to a plate and frame filter press. The filtrate discharge end of the plate and frame filter press is connected to the desulfurization liquid regeneration tower through a filtrate return pump. The top of the desulfurization liquid regeneration tower is connected to an exhaust gas purification device through an exhaust gas induced draft fan. The desulfurization liquid is injected into the desulfurization liquid regeneration tower, and then pumped to the desulfurization sprayer for spraying through the lean liquid pump. Biogas is input into the desulfurization sprayer from the biogas inlet pipe, and after being desulfurized by the desulfurization liquid spray, it is output from the biogas outlet pipe. The sprayed desulfurization liquid is pumped into the regeneration sprayer through the rich liquid pump, and undergoes oxidation and regeneration with the air sprayed from the aeration disc in the desulfurization liquid regeneration tower. The waste gas generated in the desulfurization liquid regeneration tower is purified by the waste gas purification equipment before being discharged. The desulfurization liquid containing sediment impurities at the bottom of the desulfurization liquid regeneration tower is pumped into the plate and frame filter press for filtration through the filter press pump. The filtered desulfurization liquid re-enters the desulfurization liquid regeneration tower.

[0008] Preferably, the desulfurization spray tower is provided with a slag remover shell at the bottom, the surface of the slag remover shell is provided with a through groove, an impeller is shaft-connected inside the slag remover shell, an elastic plate is connected to the bottom edge of the impeller, the elastic plate is in sliding contact with the bottom surface of the desulfurization spray tower, and the biogas input pipe is located inside the slag remover shell.

[0009] Preferably, the impeller surface is provided with a guide groove, which pushes the desulfurization liquid downward when the impeller rotates; the contact part between the elastic sheet and the impeller is provided with a number of first through holes.

[0010] Preferably, the surface of the elastic sheet is provided with a plurality of second through holes, and a guide plate is provided at the bottom of the second through holes.

[0011] The beneficial effects of adopting the above technical solution are as follows: the desulfurizing agent of the present invention has a high iron ion chelation concentration and a large sulfur capacity. Its use in the desulfurization system of the present invention can significantly improve desulfurization efficiency and effectively reduce the formation of sediment at the bottom of the desulfurization spray tower. Simultaneously, by improving the structure of the desulfurization spray tower and utilizing biogas to drive the impeller, the elastic plates continuously clean the bottom of the desulfurization spray tower, preventing the accumulation of sediment at the bottom of the desulfurization spray tower and allowing sediment impurities to quickly enter the desulfurization liquid regeneration tower through the rich liquid pump. Attached Figure Description

[0012] Figure 1This is a structural diagram of a desulfurization system in a specific embodiment of the present invention.

[0013] Figure 2 This is a structural diagram of a slag remover in a specific embodiment of the present invention. Implementation

[0014] One specific embodiment of the present invention provides a compound desulfurizing agent for wet desulfurization of biogas complexed iron, which is composed of disodium ethylenediaminetetraacetate, trisodium N-hydroxyethylethylenediaminetriacetate, ferric sulfate, and ferrous sulfate heptahydrate. The molar ratio of disodium ethylenediaminetetraacetate, trisodium N-hydroxyethylethylenediaminetriacetate, ferric sulfate, and ferrous sulfate heptahydrate is 3:2:6:2.

[0015] Reference Figure 1-2 A desulfurization method using a compound desulfurizing agent for wet desulfurization of biogas complexed iron includes the following steps: The compound desulfurizing agent was mixed with water to prepare a desulfurization solution. The iron ion chelation concentration of the desulfurization solution was 0.1197 mol / L, and the pH value was 8.5. A desulfurization system is installed, comprising a desulfurization spray tower 1, a biogas inlet pipe 2 connected to the bottom of the desulfurization spray tower 1, a biogas outlet pipe 3 connected to the top of the desulfurization spray tower 1, a desulfurization sprayer 4 fixed inside the desulfurization spray tower 1, the desulfurization sprayer 4 connected to the output end of a lean liquor pump 5, the bottom of the desulfurization spray tower 1 connected to the inlet end of a rich liquor pump 6, the output end of the rich liquor pump 6 connected to a regeneration sprayer 7, and the regeneration sprayer 7 fixed inside a desulfurization liquor regeneration tower 8 for desulfurization liquor regeneration. The bottom of the tower 8 is connected to the input end of the lean liquid pump 5. An aeration disc 9 is installed below the regeneration sprayer 7. The aeration disc 9 is connected to the Roots aerator 10. The bottom of the desulfurization liquid regeneration tower 8 is connected to the input end of the filter press pump 11. The output end of the filter press pump 11 is connected to the plate and frame filter press 12. The filtrate discharge end of the plate and frame filter press 12 is connected to the desulfurization liquid regeneration tower 8 through the filtrate return pump 13. The top of the desulfurization liquid regeneration tower 8 is connected to the waste gas purification equipment 15 through the waste gas induced draft fan 14. The desulfurization liquid is injected into the desulfurization liquid regeneration tower 8, and then pumped to the desulfurization sprayer 4 for spraying through the lean liquid pump 5. Biogas is input into the desulfurization sprayer 1 through the biogas input pipe 2, and after desulfurization by the desulfurization liquid spray, it is output from the biogas output pipe 3. The sprayed desulfurization liquid is pumped into the regeneration sprayer 7 through the rich liquid pump 6, and oxidized and regenerated with the air sprayed from the aeration disc 9 in the desulfurization liquid regeneration tower 8. The waste gas generated in the desulfurization liquid regeneration tower 8 is purified by the waste gas purification equipment 15 and then discharged. The desulfurization liquid containing sediment impurities at the bottom of the desulfurization liquid regeneration tower 8 is pumped into the plate and frame filter press 12 for filtration through the filter press pump 11. The filtered desulfurization liquid re-enters the desulfurization liquid regeneration tower 8.

[0016] A slag remover shell 16 is installed at the bottom of the desulfurization spray tower 1. A through groove 17 is provided on the surface of the slag remover shell 16. An impeller 18 is shaft-connected inside the slag remover shell 16. An elastic plate 19 is connected to the bottom edge of the impeller 18, and the elastic plate 19 slides in contact with the bottom surface of the desulfurization spray tower 1. The biogas inlet pipe 2 is located inside the slag remover shell 16. A guide groove 19 is provided on the surface of the impeller 18. When the impeller 18 rotates, the guide groove 19 pushes the desulfurization liquid downwards. Several first through holes 20 are provided at the contact point between the elastic plate 19 and the impeller 18. Several second through holes 21 are provided on the surface of the elastic plate 19, and a guide plate 22 is provided at the bottom of the second through hole 21. Biogas is injected into the slag remover shell 16 through the biogas inlet pipe 2. The biogas drives the impeller 18 to rotate, causing the elastic plate 19 to continuously clean the bottom of the desulfurization spray tower 1. As the desulfurization liquid flows downward, it flows between the through holes, causing the elastic sheet 19 to vibrate, thereby further improving the cleaning effect on the bottom of the desulfurization spray tower 1.

[0017] A torsion spring 23 is installed in the first through hole 20. A threaded hole 24 is provided on the impeller 18, and a screw 25 is internally threaded into the threaded hole 24. One end of the torsion spring 23 is connected to the screw 25, and the other end is connected to the elastic plate 19. When the elastic plate 19 cannot resonate, the tension of the torsion spring 23 on the elastic plate 19 can be changed by adjusting the screw 25, thereby changing the resonant frequency of the elastic plate 19 and increasing the vibration energy of the elastic plate 19.

[0018] In the description of this invention, it should be understood that the terms "longitudinal", "lateral", "up", "down", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0019] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A desulfurization method using a compound desulfurizing agent for wet desulfurization of biogas complexed iron, wherein the compound desulfurizing agent for wet desulfurization of biogas complexed iron is composed of disodium ethylenediaminetetraacetate, trisodium N-hydroxyethylethylenediaminetriacetate, ferric sulfate, and ferrous sulfate heptahydrate, wherein the molar ratio of disodium ethylenediaminetetraacetate, trisodium N-hydroxyethylethylenediaminetriacetate, ferric sulfate, and ferrous sulfate heptahydrate is 3:2:6:2; Its features Includes the following steps: The compound desulfurizing agent was mixed with water to prepare a desulfurization solution. The iron ion chelation concentration of the desulfurization solution was 0.1197 mol / L, and the pH value was 8.

5. A desulfurization system is set up, which includes a desulfurization spray tower (1). The bottom of the desulfurization spray tower (1) is connected to a biogas input pipe (2), and the top of the desulfurization spray tower (1) is connected to a biogas output pipe (3). A desulfurization sprayer (4) is fixed inside the desulfurization spray tower (1). The desulfurization sprayer (4) is connected to the output end of a lean liquid pump (5). The bottom of the desulfurization spray tower (1) is connected to the input end of a rich liquid pump (6). The output end of the rich liquid pump (6) is connected to a regeneration sprayer (7). The regeneration sprayer (7) is fixed inside a desulfurization liquid regeneration tower (8). (8) The bottom is connected to the input end of the lean liquid pump (5). An aeration disc (9) is installed below the regeneration sprayer (7). The aeration disc (9) is connected to the Roots aerator (10). The bottom of the desulfurization liquid regeneration tower (8) is connected to the input end of the filter press pump (11). The output end of the filter press pump (11) is connected to the plate and frame filter press (12). The filtrate discharge end of the plate and frame filter press (12) is connected to the desulfurization liquid regeneration tower (8) through the filtrate return pump (13). The top of the desulfurization liquid regeneration tower (8) is connected to the waste gas purification equipment (15) through the waste gas induced draft fan (14). The desulfurization liquid is injected into the desulfurization liquid regeneration tower (8), and then pumped to the desulfurization sprayer (4) for spraying by the lean liquid pump (5). Biogas is input into the desulfurization sprayer (1) through the biogas input pipe (2). After desulfurization by the desulfurization liquid spray, it is output from the biogas output pipe (3). The desulfurization liquid after spraying is pumped into the regeneration sprayer (7) through the rich liquid pump (6). In the desulfurization liquid regeneration tower (8), it is oxidized and regenerated with the air sprayed from the aeration plate (9). The waste gas generated in the desulfurization liquid regeneration tower (8) is purified by the waste gas purification equipment (15) and then discharged. The desulfurization liquid containing sediment impurities at the bottom of the desulfurization liquid regeneration tower (8) is pumped into the plate and frame filter press (12) for filtration by the filter press pump (11). The filtered desulfurization liquid re-enters the desulfurization liquid regeneration tower (8). The desulfurization spray tower (1) is equipped with a slag remover shell (16) at the bottom. A through groove (17) is provided on the surface of the slag remover shell (16). An impeller (18) is shaft-connected inside the slag remover shell (16). An elastic plate is connected to the bottom edge of the impeller (18). The elastic plate slides in contact with the bottom surface of the desulfurization spray tower (1). The biogas input pipe (2) is located inside the slag remover shell (16). A guide groove (19) is provided on the surface of the impeller (18). When the impeller (18) rotates, the guide groove (19) directs the desulfurization liquid towards the desulfurization process. The elastic plate is pushed downward; a number of first through holes (20) are provided at the contact part between the elastic plate and the impeller (18); a number of second through holes (21) are provided on the surface of the elastic plate, and a guide plate (22) is provided at the bottom of the second through hole (21); a torsion spring (23) is installed in the first through hole (20), a threaded hole (24) is provided on the impeller (18), and a screw (25) is connected to the threaded hole (24) internally. One end of the torsion spring (23) is connected to the screw (25), and the other end is connected to the elastic plate.

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