Salt mud pretreatment system suitable for flue gas desulfurization process

Abstract

The utility model discloses a salty mud pretreatment system suitable for a flue gas desulfurization process, and belongs to the technical field of flue gas desulfurization of alkali-making salty mud. The device comprises a process water tank and a dissolving tank, the dissolving tank is provided with a salty mud feed port and a salty mud discharge port, the salty mud feed port is provided with a blanking groove I, one side of the blanking groove I is provided with a feeding mechanism I, and the feeding mechanism I is connected with the process water tank; the other side of the blanking groove I is communicated with the dissolving tank; a filter screen I, a stirrer I and a stirrer II are arranged in the dissolving tank, the dissolving tank is divided into a feeding area and a discharging area by the filter screen I, the salty mud feeding port and the stirrer I are both located in the feeding area, the salty mud discharging port and the stirrer II are both located in the discharging area, the discharging area is connected with a salty mud output pipe, and a conveying pump is arranged on the salty mud output pipe. The method has the advantages that the pretreatment process is simple, the uniformity and no caking of the pretreated salty mud are guaranteed, the subsequent treatment efficiency and quality of SO2 in flue gas are improved, the utilization rate of the salty mud is improved, and finally, the purposes of energy conservation and emission reduction are achieved.

Description

Technical Field

[0001] The utility model relates to a pretreatment system for making alkali from salt mud, in particular to a salt mud pretreatment system applicable to the flue gas desulfurization process, belonging to the technical field of making alkali from salt mud for flue gas desulfurization. Background Technique

[0002] In the process of making alkali, saturated brine is generally used as the main raw material, and electrolysis is adopted to prepare caustic soda (sodium hydroxide). The mud discharged in this process is called "salt mud", and its main components are CaCO 3 (content about 90%), NaCl (content about 7%), Mg(OH) 2 (content about 2%), BaSO 4 and mud and sand. At present, most of the salt mud is directly dumped, piled up or buried, etc., without being thoroughly treated, which harms the environment; some adopt the comprehensive utilization method, that is, using salt mud as raw material to prepare building materials such as cement and artificial stone. However, due to various factors such as the increasing requirements for energy conservation and emission reduction, the restrictions in the building materials market and the limited annual treatment capacity, the harmless treatment and utilization of salt mud have become a huge challenge faced by the development of this industry.

[0003] In view of the fact that the main component of salt mud is CaCO 3 , its composition is the same as that of the desulfurizer - limestone powder involved in the wet flue gas desulfurization process of coal-fired flue gas. Therefore, salt mud can be used as the desulfurizer in the wet flue gas desulfurization process of coal-fired flue gas (such as: CN1830525, CN101632896, CN103230739A, CN114873890A, etc.) to solve the problem of difficult solid waste treatment of salt mud. Among them, after the SO 2 in the coal-fired flue gas is absorbed by the salt mud, the concentration of SO 2 decreases, and the flue gas in the chimney meets the emission requirements and is discharged into the atmosphere; gypsum mud is formed in the desulfurization tower, and then the gypsum mud is recycled and treated to obtain gypsum. The reaction formulas involved in the formation of gypsum mud include:

[0004] CaCO 3 +SO 2 +H 2 O →CaSO 3 ·H 2 O +CO 2 ;

[0005] CaSO 3 ·H 2 O + SO 2 + H 2 O→Ca(HSO 3 ) 2 +H 2 O

[0006] Ca(HSO 3 ) 2 +1 / 2O 2 +2H 2 O→CaSO 4 ·2H 2 O+SO 2 +H 2 O;

[0007] CaSO 3 ·H 2 O +1 / 2O 2 +2H 2 O→CaSO 4 ·2H 2 O +H 2 O;

[0008] At present, due to the deficiencies of the salt sludge itself (such as non-uniformity, caking, etc.), the efficiency of treating SO 2 in coal-fired flue gas by salt sludge is low, and problems such as poor absorption of SO 2 occur. SUMMARY OF THE INVENTION

[0009] In order to solve the problems of low efficiency and poor quality in treating SO 2 in coal-fired flue gas by existing salt sludge, a salt sludge pretreatment system applicable to the flue gas desulfurization process is proposed. Among them, by setting up a dissolution tank, it is ensured that the salt sludge after pretreatment is homogeneous and non-caking, thereby improving the treatment efficiency and quality of SO 2 in the subsequent flue gas. At the same time, the utilization rate of salt sludge is improved, and finally, the purpose of energy conservation and emission reduction is achieved.

[0010] In order to achieve the above technical objectives, the following technical solutions are proposed:

[0011] A salt sludge pretreatment system applicable to the flue gas desulfurization process includes a process water tank and a square dissolution tank. The dissolution tank is provided with a salt sludge feed inlet and a salt sludge slurry discharge outlet. A feeding chute Ⅰ is provided at the salt sludge feed inlet. On one side of the feeding chute Ⅰ, there is a feeding mechanism Ⅰ connected to the process water tank. The feeding mechanism Ⅰ is connected to the process water tank through a process water delivery pipe. On the other side of the feeding chute Ⅰ, it is communicated with the dissolution tank through the salt sludge feed inlet. A filter screen Ⅰ, a stirrer Ⅰ and a stirrer Ⅱ are arranged in the dissolution tank. The filter screen Ⅰ divides the dissolution tank into a feed zone and a discharge zone. The salt sludge feed inlet and the stirrer Ⅰ are both located in the feed zone, and the salt sludge slurry discharge outlet and the stirrer Ⅱ are both located in the discharge zone. The discharge zone is connected with a salt sludge slurry output pipe, and a delivery pump is provided on the salt sludge slurry output pipe.

[0012] Further, there are two stirrers Ⅰ and two stirrers Ⅱ, and the stirrers Ⅰ and stirrers Ⅱ are evenly distributed in the dissolution tank.

[0013] Furthermore, a desulfurizer feeding port is provided on the dissolution tank, and the desulfurizer feeding port is located in the feeding area.

[0014] Furthermore, the dissolution tank is connected to the white mud bin through the desulfurizer feeding port.

[0015] Furthermore, a second blanking chute is provided on the front side of the working station of the desulfurizer feeding port, and a second feeding mechanism connected to the process water tank is provided on one side of the second blanking chute; a second filter screen is provided between the second blanking chute and the desulfurizer feeding port.

[0016] Furthermore, the first feeding mechanism and / or the second feeding mechanism are also connected to the dehydration device in the gypsum mud recovery and treatment system through a filtrate recovery pipe, and the gypsum mud recovery and treatment system is connected to the desulfurization tower.

[0017] Furthermore, the slurry output pipe is connected to the process water delivery pipe and / or the filtrate recovery pipe through a backwashing pipe. When the transfer pump stops pumping the salt slurry, the salt slurry output pipe is backwashed with process water to prevent the salt slurry from depositing in the salt slurry output pipe and affecting the smoothness of the next transfer process.

[0018] Furthermore, the salt mud pretreatment system further includes a salt mud bin and a salt slurry temporary storage tank. The salt mud bin is arranged on the front side of the working station of the dissolution tank, and the salt slurry temporary storage tank is arranged on the rear side of the working station of the dissolution tank. A continuous path for temporarily storing the homogenized salt mud is formed among the salt mud bin, the dissolution tank, and the salt slurry temporary storage tank. Among them, the salt mud bin is used for collecting and temporarily storing the salt mud discharged from the self-made alkali production line, and the salt slurry temporary storage tank is used for temporarily storing the homogenized salt slurry discharged from the dissolution tank, which can better connect the dissolution tank and the desulfurization tower and ensure the stability, orderliness, and controllability of the salt mud desulfurization process.

[0019] Furthermore, the salt slurry temporary storage tank is connected to a limestone powder bin.

[0020] In this technical solution, the number of transfer pumps, as well as the number, connection relationship, and specific layout of each pipeline, can be specifically set according to actual needs.

[0021] The relationships of "upper", "inner", "rear side of the working station", "front side of the working station", and "side" involved in this technical solution are defined according to the actual use status, which are conventional terms in this technical field and also conventional terms for those skilled in the art during actual use.

[0022] Adopting this technical solution brings the following beneficial technical effects:

[0023] 1) By arranging the dissolution tank, process water tank, etc., the present utility model ensures that the salt mud after pretreatment is homogeneous and free of lumps, thereby improving the treatment efficiency and quality of SO in the subsequent flue gas. 2 At the same time, the utilization rate of the salt mud is improved, and finally, the purpose of energy conservation and emission reduction is achieved.

[0024] 2) In the present utility model, a salt sludge feed inlet, a process water inlet, and a salt mud slurry discharge outlet are provided on the dissolution tank to ensure the orderly entry of materials and solvents into the dissolution tank. After dissolution and homogenization, they are then discharged out of the dissolution tank in an orderly manner. A filter screen I, a stirrer I, and a stirrer II are provided in the dissolution tank. Moreover, through the effective arrangement of the filter screen I, the stirrer I, and the stirrer II, it is ensured that the salt sludge dissolves quickly and is in a homogeneous state, without caking or settling to the bottom, etc., which is convenient for subsequent use in the desulfurization tower and provides an effective prerequisite guarantee for the treatment process of SO 2 in the flue gas. Description of the Drawings

[0025] Figure 1 is a schematic diagram of the working principle related to the present utility model;

[0026] Figure 2 is a physical diagram of the salt sludge (lumpy salt sludge) related to the present utility model;

[0027] Figure 3 is a physical diagram of the salt mud slurry (homogeneous salt sludge, flowing state) related to the present utility model;

[0028] In the figure, 1. process water tank, 2. dissolution tank, 21. salt sludge feed inlet, 22. filter screen I, 23. stirrer I, 24. stirrer II, 25. feeding area, 26. discharging area, 3. process water delivery pipe, 4. salt mud slurry output pipe, 5. delivery pump, 6. white mud bin, 7. salt sludge bin, 8. salt mud slurry temporary storage tank, 9. filtrate recovery pipe, 10. backwashing pipe, 11. feeding chute I, 12. feeding mechanism I, 13. feeding chute II, 14. feeding mechanism II, 15. dehydration device, 16. filter screen II. Detailed Embodiments

[0029] The technical solutions in the embodiments of the present utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present utility model.

[0030] Embodiment 1

[0031] This embodiment proposes a salt sludge pretreatment system applicable to the flue gas desulfurization process, such as Figure 1As shown, it includes a process water tank 1 and a square dissolution tank 2, the dissolution tank 2 is provided with a salt mud feed port 21 and a salt mud slurry discharge port, the salt mud feed port 21 is provided with a feed chute Ⅰ11, and one side of the feed chute Ⅰ11 is provided with a feeding mechanism Ⅰ12 connected to the process water tank 1 (specifically, it can be a fire monitor, that is, the salt mud is flushed into the dissolution tank 2 by the process water), and the feeding mechanism Ⅰ12 is connected to the process water tank 1 through a process water delivery pipe 3; the feed chute Ⅰ1 The other side is connected with the dissolving tank 2 through the salt mud feed port 21; the dissolving tank 2 is provided with a filter screen Ⅰ 22, a stirrer Ⅰ 23 and a stirrer Ⅱ 24; the filter screen Ⅰ 22 divides the dissolving tank 2 into a feed area 25 and a discharge area 26; the salt mud feed port 21 and the stirrer Ⅰ 23 are both located in the feed area 25; the salt mud discharge port and the stirrer Ⅱ 24 are both located in the discharge area 26; the discharge area 26 is connected with a salt mud output pipe 4, and a delivery pump 5 is provided on the salt mud output pipe 4.

[0032] Among them, according to actual needs, the dissolution tank 2 can also be a circular dissolution tank 2, as long as it is ensured that under the action of the agitator, the dissolution tank 2 has no dead corners, that is, the salt slurry is in a flowing state (not a static state), does not agglomerate, and does not sink to the bottom.

[0033] The pore size of the filter screen Ⅰ22 is 10*10mm. The setting of the filter screen Ⅰ22 not only realizes the filtering effect on the salt mud, but also partitions the dissolution tank 2, ensuring that the salt mud finally enters the salt mud output pipe 4 in a homogeneous state and then is discharged.

[0034] Example 2

[0035] On the basis of Example 1, this example further limits the number and arrangement of agitators I 23 and II 24 in the dissolving tank 2 to further illustrate the technical solution.

[0036] There are two agitators I23 and two agitators II24, and the agitators I23 and II24 are evenly distributed in the dissolution tank 2. "Evenly distributed" specifically means that the four agitators are distributed on the same horizontal plane, and the four agitators are respectively located at the four corners of the rectangle. This setting ensures that the salt mud is subjected to uniform stirring force and keeps it in a dynamic flow state to prevent it from sinking to the bottom and agglomerating due to stillness. Finally, the salt mud enters the desulfurization tower in a homogeneous state, ensuring the treatment efficiency and quality of SO2 in the flue gas; at the same time, it facilitates the stable and effective transportation of the salt mud.

[0037] In addition, when salt mud is added, due to the block shape of salt mud (such as Figure 2 As shown in the figure), four agitators can be turned on to work simultaneously. At this time, the agitators are mainly used to break up, dissolve and homogenize the salt mud; after a period of time, the two agitators on the diagonal line can be turned off. At this time, the agitators are mainly used to maintain the dissolved salt mud in a homogenous state (as shown in the figure). Figure 3as shown in the figure), to prevent the salt mud from settling to the bottom, etc. The control of this working process reduces energy consumption and improves the service life of the agitator on the premise of ensuring the stable and effective preparation process of the salt mud.

[0038] Among them, the motor power of the two agitators Ⅰ23 is 15KW, and the motor power of the two agitators Ⅱ24 is 11KW; in addition, the rotation speed of the agitator can be set according to actual needs, such as: 85.88r / min.

[0039] Example 3

[0040] On the basis of Examples 1-2, in this example, when the salt mud cannot meet the requirements, other desulfurizing agents (such as white mud from paper mills, which mainly contains calcium carbonate) are replenished into the dissolution tank 2 through the desulfurizing agent feeding port on the dissolution tank 2 to ensure the smooth progress of the desulfurization process.

[0041] Specifically: There is also a desulfurizing agent feeding port on the dissolution tank 2. The desulfurizing agent feeding port is located in the feeding area 25. The dissolution tank 2 is connected to the white mud bin 6 through the desulfurizing agent feeding port. There is a feeding chute Ⅱ13 on the front side of the working position of the desulfurizing agent feeding port. One side of the feeding chute Ⅱ13 is provided with a feeding mechanism Ⅱ14 connected to the process water tank 1 (specifically, it can be a fire monitor, that is, powered by process water to flush the white mud into the dissolution tank 2). Since there are many impurities in the white mud, a filter screen Ⅱ16 is provided between the feeding chute Ⅱ13 and the desulfurizing agent feeding port. After removing some impurities, it then enters the dissolution tank 2.

[0042] According to the space limitation of the plant, the salt mud feeding port 21 and the desulfurizing agent feeding port can be set as the same feeding port, and the feeding chute Ⅰ11 is arranged above the feeding chute Ⅱ13, that is, both the feeding chute Ⅰ11 and the feeding chute Ⅱ13 converge to the feeding port. In addition, the white mud can also be directly fed into the feeding chute Ⅱ13 through a white mud transport vehicle and flushed into the dissolution tank 2 by process water or filtrate. During this process, the filter screen Ⅱ16 filters the impurities in the white mud to ensure that the white mud entering the dissolution tank 2 is clean, thereby ensuring the stable subsequent transportation and desulfurization efficiency of the white mud slurry.

[0043] Example 4

[0044] On the basis of Examples 1-3, this example further limits the layout of the dissolution tank 2 to further illustrate this technical solution.

[0045] The salt sludge pretreatment system further includes a salt sludge bin 7 and a salt mud slurry temporary storage tank 8. The salt sludge bin 7 is arranged on the front side of the working station of the dissolving tank 2, and the salt mud slurry temporary storage tank 8 is arranged on the rear side of the working station of the dissolving tank 2. A continuous passage for temporarily storing the homogenized salt sludge is formed among the salt sludge bin 7, the dissolving tank 2, and the salt mud slurry temporary storage tank 8. Among them, the salt sludge bin 7 is used for collecting and temporarily storing the salt sludge discharged from the self-made alkali production line, and the salt mud slurry temporary storage tank 8 is used for temporarily storing the homogenized salt mud slurry discharged from the dissolving tank 2, which can better connect the dissolving tank 2 with the desulfurization tower and ensure the stability, orderliness, and controllability of the salt sludge desulfurization process.

[0046] The salt mud slurry temporary storage tank 8 is connected to a limestone powder bin. In the case where the salt sludge and other desulfurizing agents cannot be supplied in time, the limestone powder in the limestone powder bin is used to urgently prepare the slurry to ensure the smooth progress of the desulfurization process.

[0047] In addition, the salt sludge can also be directly fed into the feeding chute I 11 through a salt sludge transport vehicle and flushed into the dissolving tank 2 by process water or filtrate.

[0048] Example 5

[0049] On the basis of Examples 1-4, in order to achieve the purposes of saving water resources, energy conservation, and emission reduction, this example further defines:

[0050] The feeding mechanism I 12 and / or the feeding mechanism II 14 are also connected to the dehydration device 15 in the gypsum mud recovery and treatment system through a filtrate recovery pipe 9, and the gypsum mud recovery and treatment system is connected to the desulfurization tower.

[0051] In practical applications, first, the filtrate discharged from the dehydration device 15 in the gypsum mud recovery and treatment system is used. In this way, the makeup water volume can be reduced, that is, the water balance of the flue gas desulfurization system can be maintained; in the case of insufficient filtrate, process water will be used.

[0052] Example 6

[0053] Due to the particularity of the salt mud slurry, such as easy caking, easy agglomeration, easy sedimentation, etc., on the basis of Example 6, in order to better connect the external transportation of the salt sludge after dissolution and homogenization in different batches, this example further defines:

[0054] The salt mud slurry output pipe 4 is connected to the process water delivery pipe 3 and / or the filtrate recovery pipe 9 through a backwashing pipe 10. When the delivery pump 5 stops pumping the salt mud slurry, the salt mud slurry output pipe 4 is backwashed with process water and / or the filtrate discharged from the dehydration device 15 to prevent the salt mud slurry from depositing in the salt mud slurry output pipe 4 and affecting the smoothness of the next transportation process.

Claims

1. Salt mud pretreatment system suitable for flue gas desulfurization process, characterized by: The invention comprises a process water tank (1) and a square dissolution tank (2), wherein the dissolution tank (2) is provided with a salt mud feed port (21) and a salt mud slurry discharge port, a feed chute I (11) is provided at the salt mud feed port (21), a feeding mechanism I (12) connected to the process water tank (1) is provided on one side of the feed chute I (11), and the feeding mechanism I (12) is connected to the process water tank (1) through a process water delivery pipe (3); the other side of the feed chute I (11) is connected to the dissolution tank (2) through the salt mud feed port (21); A filter screen I (22), an agitator I (23) and an agitator II (24) are provided in the dissolving tank (2). The filter screen I (22) divides the dissolving tank (2) into a feed zone (25) and a discharge zone (26). The salt mud feed port (21) and the agitator I (23) are both located in the feed zone (25). The salt mud discharge port and the agitator II (24) are both located in the discharge zone (26). The discharge zone (26) is connected to a salt mud output pipe (4). A delivery pump (5) is provided on the salt mud output pipe (4).

2. The salt mud pretreatment system suitable for flue gas desulfurization process according to claim 1 is characterized in that: There are two agitators I (23) and two agitators II (24), and the agitators I (23) and the agitators II (24) are evenly distributed in the dissolution tank (2).

3. The salt mud pretreatment system suitable for flue gas desulfurization process according to claim 1 is characterized in that: The dissolution tank (2) is also provided with a desulfurizing agent feeding port, and the desulfurizing agent feeding port is located in the feeding area (25).

4. The salt mud pretreatment system suitable for flue gas desulfurization process according to claim 3 is characterized in that: The dissolution tank (2) is connected to the white mud bin (6) via a desulfurizing agent feeding port.

5. The salt mud pretreatment system suitable for flue gas desulfurization process according to claim 4 is characterized in that: A feed trough II (13) is provided at the front side of the station of the desulfurizing agent feeding port, and a feeding mechanism II (14) connected to the process water tank (1) is provided on one side of the feed trough II (13); a filter screen II (16) is provided between the feed trough II (13) and the desulfurizing agent feeding port.

6. The salt mud pretreatment system suitable for flue gas desulfurization process according to claim 5 is characterized in that: The feeding mechanism I (12) and / or the feeding mechanism II (14) are also connected to a dehydration device (15) in a gypsum mud recovery and treatment system via a filtrate recovery pipe (9), and the gypsum mud recovery and treatment system is connected to a desulfurization tower.

7. The salt mud pretreatment system suitable for flue gas desulfurization process according to claim 6 is characterized in that: The salt slurry output pipe (4) is connected to the process water delivery pipe (3) and / or the filtrate recovery pipe (9) via a backwash pipe (10).

8. The salt mud pretreatment system suitable for flue gas desulfurization process according to claim 1 is characterized in that: The salt mud pretreatment system further comprises a salt mud bin (7) and a salt mud temporary storage box (8), wherein the salt mud bin (7) is arranged at the front side of the workstation of the dissolution tank (2), and the salt mud temporary storage box (8) is arranged at the rear side of the workstation of the dissolution tank (2), and a continuous passage for temporary storage of the salt mud after homogenization is formed between the salt mud bin (7), the dissolution tank (2) and the salt mud temporary storage box (8).

9. The salt mud pretreatment system suitable for flue gas desulfurization process according to claim 8 is characterized in that: The salt slurry temporary storage box (8) is connected to a limestone powder bin.

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