System for removing sulfate radicals in saline water for chlor-alkali industry and operation method of system

Abstract

The invention belongs to the field of chemical equipment, and particularly relates to a system for removing sulfate radicals in saline water for the chlor-alkali industry and an operation method thereof.The system comprises a clarifying barrel, a downcomer is arranged on the upper portion in the clarifying barrel, the upper portion of the downcomer is communicated with an outlet of a baffling pipe, and an inlet of the baffling pipe is communicated with a barium chloride pipe and a saline water pipe; a liquid outlet pipe is arranged at the upper end of the side wall of the clarification barrel, one end of the liquid outlet pipe is communicated with the interior of the clarification barrel, the other end of the liquid outlet pipe is communicated with a water distribution barrel arranged outside the clarification barrel, the baffle pipe comprises a pipe body, multiple groups of baffle plates are arranged on two sides in the pipe body in a staggered manner, and a discharge port is formed in the bottom of the clarification barrel; the system provided by the invention can be used for effectively separating sediments and clarified liquor in the system, so that the service life of the inorganic ceramic membrane can be prolonged while the content of sulfate radicals in the chlor-alkali industrial brine is reduced, thereby providing reliable and effective guarantee for the chlor-alkali production process.

Description

Technical Field

[0001] The present invention belongs to the field of chemical equipment, and in particular relates to a system for removing sulfate from brine used in the chlor-alkali industry and an operating method thereof. Background Art

[0002] In chlor-alkali systems, brine carries a certain amount of sulfate. This is due in part to the introduction of raw salt, and also to the oxidation of sodium sulfite, added to remove free chlorine during the dechlorination and brine refining processes. Excessive sulfate concentrations in the brine can adversely affect the production process and product quality, so it is crucial to ensure that the sulfate concentration in the brine does not exceed a set value.

[0003] Sulfate ions are usually removed by absorbing barium chloride to form barium sulfate precipitates. However, due to the strong adhesion of barium sulfate, during the production process, barium sulfate precipitates will adhere to and accumulate on the membrane tube walls of the inorganic ceramic membrane filtration equipment, causing the inorganic ceramic membrane filtration pores to gradually become clogged, the operating pressure to increase, the brine output to decrease, and the membrane tubes to be difficult to clean and easily damaged.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention proposes a system for removing sulfate from brine used in the chlor-alkali industry and an operating method thereof. The system proposed by the present invention can effectively separate the precipitate from the clarified liquid, thereby reducing the sulfate content in the chlor-alkali industrial brine and extending the life of the inorganic ceramic membrane, thereby providing reliable and effective protection for the chlor-alkali production process.

[0006] To achieve the above object, the present invention adopts the following technical solutions: The present invention proposes a system for removing sulfate ions from brine for the chlor-alkali industry, comprising a clarification barrel, wherein a downcomer is provided at the upper inner portion of the clarification barrel, the upper portion of the downcomer is connected to the outlet of a baffle pipe, the inlet of the baffle pipe is connected to a barium chloride pipe and a brine pipe, a liquid outlet pipe is provided at the upper end of a side wall of the clarification barrel, one end of the liquid outlet pipe is connected to the interior of the clarification barrel, and the other end is connected to a water distribution barrel arranged outside the clarification barrel, the baffle pipe comprises a tube body, a plurality of groups of baffles are staggeredly provided on both sides of the tube body, and a discharge port is provided at the bottom of the clarification barrel.

[0007] Specifically, a collecting chamber is further provided in the upper part of the clarification barrel, and the collecting chamber is located outside the downcomer. The collecting chamber is communicated with one end of the liquid inlet pipe, and the other end of the liquid inlet pipe is sealed with the inner wall of the clarification barrel. A plurality of small holes are arranged at intervals on the wall of the liquid inlet pipe, and the end of the liquid outlet pipe located inside the clarification barrel is communicated with the interior of the collecting chamber.

[0008] Specifically, the collection chamber is an annular cavity, which is sleeved on the upper part of the downcomer. A plurality of liquid inlet pipes are arranged circumferentially between the annular cavity and the clarification barrel. One end of the liquid inlet pipe is connected to the side wall of the annular cavity, and the other end is connected to the inner wall of the clarification barrel.

[0009] Specifically, the top of the clarification barrel is provided with an upper cover matching its mouth, the downpipe passes through the upper cover up and down and is fixedly connected to the upper cover, and the upper cover is also provided with a first manhole.

[0010] Specifically, the bottom of the clarification tank is a conical bottom, a second manhole is provided on the wall of the conical bottom, and the conical angle of the conical bottom is 60° to 90°.

[0011] Specifically, a cleaning pipe is spirally arranged from bottom to top on the inner wall of the conical bottom, and a plurality of through holes are evenly arranged on the lower side of the cleaning pipe. The inlet end of the cleaning pipe passes through the clarification barrel and is connected to the clean water tank and the air compressor respectively, and the inlet end passes through the clarification barrel and is connected to the collection tank. The inner wall of the clarification barrel is coated with a glass flake anti-corrosion layer.

[0012] Specifically, a plurality of groups of baffles are arranged at intervals in the baffle trough, and a skylight is correspondingly opened on the tube body at the upper end of each group of baffles.

[0013] Specifically, reinforcing ribs are provided at intervals along the circumferential direction between the lower end of the downcomer and the clarification barrel, one end of the reinforcing ribs is connected to the inner wall of the clarification barrel, and the other end is connected to the side wall of the downcomer.

[0014] Specifically, the outer diameter of the outlet end of the deflector is smaller than the inner diameter of the downcomer, and the length of the downcomer inside the clarification tank is 1 / 3 to 1 / 2 of the inner height of the clarification tank.

[0015] The present invention also provides an operating method for a system for removing sulfate radicals from brine used in the chlor-alkali industry. The barium chloride solution and brine enter a baffle tube through a barium chloride tube and a brine tube, respectively. The barium chloride solution and brine entering the baffle tube are mixed and then enter a clarification tank through a downcomer for reaction. The barium sulfate precipitate generated by the barium chloride solution and sulfate radicals in the brine settles at the bottom of the clarification tube. The clarified liquid in the upper part of the clarification tube enters a collection chamber through a small hole. The clarified liquid in the collection chamber flows into a water distribution tank through a liquid outlet pipe.

[0016] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects: (1) The present invention allows the barium chloride solution and the brine to be fully mixed through a deflection tube and then enter the clarification barrel for reaction. The barium sulfate precipitate generated by the barium chloride solution and the sulfate radical in the brine settles at the bottom of the clarification barrel. The precipitate is regularly cleaned through the discharge port at the bottom of the clarification barrel. The upper clarified liquid in the clarification barrel flows into the water distribution barrel through the liquid outlet pipe. The present invention can not only remove the sulfate radical in the brine, but also effectively separate the barium sulfate precipitate from the clarified liquid, avoid clogging of the inorganic ceramic membrane, and extend the life of the inorganic ceramic membrane, thereby providing reliable and effective protection for the production of chlor-alkali.

[0017] (2) The barium chloride solution and brine of the present invention first enter the baffle tube before entering the clarification tank. The barium chloride solution and brine form irregular motion in the baffle tube and generate strong vortex near the baffle, thereby promoting uniform mixing of the barium chloride solution and brine, ensuring sufficient reaction between the barium ions in the barium chloride solution and the sulfate ions in the brine.

[0018] (3) The present invention provides a downcomer and a collecting chamber at the upper part of the clarification barrel. The collecting chamber is located outside the downcomer and is connected to the interior of the clarification barrel through a small hole on the liquid inlet pipe and is connected to the water distribution barrel through a liquid outlet pipe. When the liquid in the deflector pipe enters the clarification barrel through the downcomer, it will not disturb the clarified liquid outside the downcomer, ensuring that the liquid entering the collecting chamber is clarified liquid. The clarified liquid in the upper part of the clarification barrel enters the collecting chamber through the small hole on the liquid inlet pipe. On the one hand, it can filter out larger impurities, and on the other hand, it can make the clarified liquid in the upper part of the clarification barrel flow more calmly, without disturbing the turbid liquid in the lower part of the clarification barrel and affecting the effect of solid-liquid separation.

[0019] (4) The present invention has a cleaning pipe spirally arranged from bottom to top on the inner wall of the conical bottom of the clarification barrel. A plurality of through holes are evenly arranged on the lower side of the cleaning pipe. The through holes are arranged on the lower side of the cleaning pipe to prevent clogging by sediments. The inlet end of the cleaning pipe passes through the clarification barrel and is connected to the clean water tank and the air compressor respectively. Clean water or compressed air can be regularly filled into the cleaning pipe for blowing and cleaning to avoid a large amount of sediment adhering to the wall of the conical bottom. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are incorporated in and constitute a part of this specification and, together with the description, serve to explain the principles of the invention.

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0022] Figure 1 Schematic diagram of the overall structure of the system for removing sulfate from brine of the present invention; Figure 2 Schematic diagram of the structure of the baffle tube of the present invention; Figure numerals: 1, clarification barrel; 101, discharge port; 102, conical bottom; 103, second manhole; 2, downcomer; 3, reinforcing rib; 4, support base; 5, collection chamber; 6, liquid outlet pipe; 7, liquid inlet pipe; 8, upper cover; 801, first manhole; 9, deflector; 901, pipe body; 902, deflector; 10, brine pipe; 11, barium chloride pipe; 12, water distribution barrel. DETAILED DESCRIPTION

[0023] Exemplary embodiments will be described in detail herein, examples of which are illustrated in the accompanying drawings. In the following description, when referring to the drawings, identical numerals in different figures represent identical or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments are not intended to represent all possible embodiments consistent with the present invention. Rather, they are merely examples of arrangements consistent with certain aspects of the present invention as detailed in the appended claims.

[0024] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. Example

[0025] A portion of the brine exiting the ion-exchange membrane electrolyzer flows back into the electrolyzer to prevent electrochemical corrosion of the anolyte inlet manifold. The remaining brine is adjusted to a pH of 1.0-1.5 with hydrochloric acid before entering the dechlorination tower for vacuum dechlorination. The chlorine gas removed is then fed into the chlorine manifold. The brine exiting the dechlorination tower is adjusted to a pH of 9-11 with NaOH, and then NaSO is added to remove free chlorine. The brine from which free chlorine has been removed requires sulfate removal.

[0026] refer to Figure 1 and Figure 2 This embodiment provides a system for removing sulfate from brine for the chlor-alkali industry, comprising a clarification barrel 1, wherein a downcomer 2 is provided at the upper inner portion of the clarification barrel 1, wherein the upper portion of the downcomer 2 is connected to the outlet of a baffle 9, and the inlet of the baffle 9 is connected to a barium chloride tube 11 and a brine tube 10. A liquid outlet pipe 6 is provided at the upper end of the side wall of the clarification barrel 1, wherein one end of the liquid outlet pipe 6 is connected to the interior of the clarification barrel 1, and the other end is connected to a water distribution barrel 12 provided outside the clarification barrel 1. The baffle 9 includes a tube body 901, wherein a plurality of baffles 902 are staggeredly provided on both sides of the tube body 901, and the baffles 902 are preferably semicircular. A discharge port 101 is provided at the bottom of the clarification barrel 1.

[0027] In this embodiment, the barium chloride solution and the brine from which free chlorine has been removed (hereinafter referred to as brine) enter the baffle tube 9 through the barium chloride tube 11 and the brine tube 10, respectively. The barium chloride solution and the brine in the baffle tube 9 are fully mixed during the flow process and finally enter the clarification tank 1 for reaction. In the clarification tank 1, the barium chloride solution and the sulfate radicals in the brine form a barium sulfate precipitate that settles at the bottom of the clarification tank 1. The clarified liquid in the upper portion of the clarification tank 1 can flow into the water distribution tank 12 for standby use through the liquid outlet pipe 6. The precipitate at the bottom of the clarification tank 1 can be cleaned through the discharge port 101 at the bottom of the clarification tank 1. In this embodiment, while removing the sulfate radicals in the brine, the barium sulfate precipitate can also be effectively separated from the clarified liquid.

[0028] In the above embodiment, in order to further promote the rapid and sufficient reaction of barium ions in the barium chloride solution with sulfate ions in the brine, the deflector tube 9 can be set to have an outer diameter at the outlet end smaller than the inner diameter of the downcomer 2, so that there is a gap between the deflector tube 9 and the downcomer 2, and the upper end of the downcomer 2 is open and connected to the atmosphere. The length of the downcomer 2 located inside the clarification barrel 1 is 1 / 3 to 1 / 2 of the internal height of the clarification barrel 1, preferably 1 / 3 in this embodiment. The outlet end of the deflector tube 9 is preferably located in the upper part of the downcomer 2. The presence of the downcomer 2 can prevent the liquid in the deflector tube 9 from disturbing the clarified liquid outside the downcomer 2 when entering the clarification barrel 1, and does not affect the collection of the clarified liquid. The upper end of the downcomer 2 is open, and the liquid in the deflector tube 9 falls due to the impact of the height difference, which is more conducive to fusion and reaction.

[0029] When collecting the clarified liquid, in order to prevent the flow of the upper clarified liquid from disturbing the turbid liquid in the lower part of the clarification barrel 1, in the above embodiment, a collection chamber 5 may be further provided in the upper part of the clarification barrel 1. The collection chamber 5 is located above the exterior of the downcomer 2. The collection chamber 5 is communicated with one end of a liquid inlet pipe 7, the other end of which is sealed with the inner wall of the clarification barrel 1. A plurality of small holes are provided at intervals on the wall of the liquid inlet pipe 7, the size of which can be determined according to design requirements. The end of the liquid outlet pipe 6 located inside the clarification barrel 1 is communicated with the interior of the collection chamber 5. The clarified liquid in the upper part of the clarification barrel 1 seeps into the collection chamber 5 through the small holes on the liquid inlet pipe 7. This can filter out larger impurities on the one hand, and on the other hand, can make the flow of the clarified liquid in the upper part of the clarification barrel 1 relatively calm, without disturbing the turbid liquid in the lower part of the clarification barrel 1 and affecting the effect of solid-liquid separation. The collecting chamber 5 is preferably configured as an annular cavity, which is sleeved on the upper part of the downcomer 2. Multiple liquid inlet pipes 7 can be provided, and the number can be determined according to design requirements. Multiple liquid inlet pipes 7 are arranged circumferentially between the annular cavity and the clarification barrel 1. One end of the liquid inlet pipe 7 is connected to the side wall of the annular cavity, and the other end is connected to the inner wall of the clarification barrel 1. The provision of multiple liquid inlet pipes 7 can, on the one hand, enable the upper clarified liquid in the clarification barrel 1 to evenly enter the collecting chamber 5, thereby ensuring the discharge efficiency of the clarified liquid, and on the other hand, strengthen the internal structure of the clarification barrel 1.

[0030] In order to better separate the precipitate from the clarified liquid, the bottom of the clarifying barrel 1 in the above embodiment can be a conical bottom 102 with a conical angle of 60°-90°, preferably 60°.

[0031] A cleaning pipe can also be arranged on the inner wall of the conical bottom 102 from bottom to top in a spiral manner, the lower side of the cleaning pipe is uniformly provided with a plurality of through holes, the water jet angle of the through holes can be determined according to design requirements, the diameter of the through holes is preferably 6 mm, the inlet end of the cleaning pipe penetrates out of the clarifying barrel 1 and is in communication with the clean water tank and the air compressor respectively, the inlet end penetrates out of the clarifying barrel 1 and is in communication with the collection pool, the conical bottom 102 can be blown and cleaned by periodically filling clean water or compressed air in the cleaning pipe, so as to prevent the precipitate from adhering to the wall of the conical bottom 102. In order to prevent the inner wall of the clarifying barrel 1 from being corroded, a glass flake anticorrosive layer can be coated on the inner wall of the clarifying barrel 1. When coating the anticorrosive layer, more anticorrosive layer can be coated at the connection between the cleaning pipe and the inner wall of the clarifying barrel 1, so as to fill the dead angle at the connection between the cleaning pipe and the inner wall of the clarifying barrel 1, and prevent the precipitate from being stuck in the dead angle and being unable to be cleaned.

[0032] In the above embodiment, a plurality of groups of baffle plates 902 are arranged in the baffle tank at intervals, a skylight is formed in the pipe body 901 at the upper end of each group of baffle plates 902, which facilitates the machining of the straight-flow pipe, facilitates the arrangement of the baffle plates 902 inside the pipe body 901, and facilitates the observation of the flow of the liquid in the baffle plates 902.

[0033] In order to ensure the structural strength of the entire clarifying barrel 1, a plurality of reinforcing ribs 3 are arranged at intervals in the circumferential direction between the lower end of the downcomer 2 and the clarifying barrel 1, one end of the reinforcing rib 3 is connected with the inner wall of the clarifying barrel 1, and the other end is connected with the side wall of the downcomer 2. In order to further improve the reinforcing effect, a plurality of annular reinforcing ribs 3 with different diameters can also be arranged between the lower end of the downcomer 2 and the clarifying barrel 1, the annular reinforcing rib 3 is sleeved on the outside of the downcomer 2 and is fixedly connected with the reinforcing rib 3.

[0034] In the above embodiment, the clarifying barrel 1 is provided with an upper cover 8 matched with the mouth portion thereof at the top end, the downcomer 2 penetrates through the upper cover 8 and is fixedly connected therewith, a first manhole 801 is further arranged on the upper cover 8 for facilitating the observation of the inside of the clarifying barrel 1, and a second manhole 103 is arranged on the wall of the conical bottom 102 of the clarifying barrel 1.

[0035] In order to lift the clarifying barrel 1, support seats 4 can be correspondingly arranged on the two sides of the clarifying barrel 1, and the clarifying barrel 1 can be lifted on the support by the support seats 4.

[0036] In the above embodiment, the flow rate of the liquid in each pipeline can be determined according to design requirements.

[0037] The foregoing description is intended only to provide specific embodiments of the present invention, which will enable those skilled in the art to understand and implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention.

[0038] It should be understood that the present invention is not limited to the above description and that various modifications and changes may be made without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A system for removing sulfate from brine in the chlor-alkali industry, characterized in that: The invention comprises a clarification barrel (1), wherein a downcomer (2) is provided at the upper inner portion of the clarification barrel (1), wherein the upper portion of the downcomer (2) is communicated with the outlet of a baffle pipe (9), and the inlet of the baffle pipe (9) is communicated with a barium chloride pipe (11) and a brine pipe (10), and a liquid outlet pipe (6) is provided at the upper end of the side wall of the clarification barrel (1), wherein one end of the liquid outlet pipe (6) is communicated with the interior of the clarification barrel (1), and the other end is communicated with a water distribution barrel (12) provided outside the clarification barrel (1), and the baffle pipe (9) comprises a tube body (901), wherein a plurality of baffle plates (902) are staggeredly provided on both sides of the interior of the tube body (901), and a discharge port (101) is provided at the bottom of the clarification barrel (1).

2. The system for removing sulfate from brine for the chlor-alkali industry according to claim 1, characterized in that: A collecting chamber (5) is further provided in the upper inner portion of the clarification barrel (1). The collecting chamber (5) is located outside the downcomer (2). The collecting chamber (5) is communicated with one end of a liquid inlet pipe (7). The other end of the liquid inlet pipe (7) is sealedly connected to the inner wall of the clarification barrel (1). A plurality of small holes are provided at intervals on the wall of the liquid inlet pipe (7). One end of the liquid outlet pipe (6) located inside the clarification barrel (1) is communicated with the interior of the collecting chamber (5).

3. The system for removing sulfate from brine for the chlor-alkali industry according to claim 2, characterized in that: The collecting chamber (5) is an annular cavity, which is sleeved on the upper part of the downcomer (2). A plurality of liquid inlet pipes (7) are arranged at intervals along the circumferential direction between the annular cavity and the clarification barrel (1). One end of the liquid inlet pipe (7) is connected to the side wall of the annular cavity, and the other end is connected to the inner wall of the clarification barrel (1).

4. The system for removing sulfate from brine for the chlor-alkali industry according to claim 1, characterized in that: The top of the clarification barrel (1) is provided with an upper cover (8) matching its mouth, the downpipe (2) passes through the upper cover (8) from top to bottom and is fixedly connected thereto, and the upper cover (8) is also provided with a first manhole (801).

5. The system for removing sulfate from brine for the chlor-alkali industry according to claim 1, characterized in that: The bottom of the clarification barrel (1) is a conical bottom (102), a second manhole (103) is provided on the wall of the conical bottom (102), and the conical angle of the conical bottom (102) is 60° to 90°.

6. The system for removing sulfate from brine for the chlor-alkali industry according to claim 5, characterized in that: A cleaning pipe is spirally arranged on the inner wall of the conical bottom (102) from bottom to top, and a plurality of through holes are evenly arranged on the lower side of the cleaning pipe. The inlet end of the cleaning pipe passes through the clarification barrel (1) and is connected to the clean water tank and the air compressor respectively. The inlet end passes through the clarification barrel (1) and is connected to the collection tank. The inner wall of the clarification barrel (1) is coated with a glass flake anti-corrosion layer.

7. The system for removing sulfate from brine for the chlor-alkali industry according to claim 1, characterized in that: Multiple groups of baffles (902) are arranged at intervals in the baffle tube (9), and a skylight is correspondingly provided on the tube body (901) at the upper end of each group of baffles (902).

8. The system for removing sulfate from brine for the chlor-alkali industry according to claim 1, characterized in that: Reinforcing ribs (3) are provided at intervals along the circumferential direction between the lower end of the downcomer (2) and the clarification barrel (1); one end of the reinforcing rib (3) is connected to the inner wall of the clarification barrel (1), and the other end is connected to the side wall of the downcomer (2).

9. The system for removing sulfate from brine for the chlor-alkali industry according to claim 1, characterized in that: The outer diameter of the outlet end of the deflector tube (9) is smaller than the inner diameter of the downcomer (2), and the length of the downcomer (2) inside the clarification barrel (1) is 1 / 3 to 1 / 2 of the inner height of the clarification barrel (1).

10. The method for operating the system for removing sulfate from brine used in the chlor-alkali industry according to claim 2, characterized in that: The barium chloride solution and the brine enter the baffle tube (9) through the barium chloride tube (11) and the brine tube (10) respectively. The barium chloride solution and the brine mixed in the baffle tube (9) enter the clarification tank (1) through the downcomer (2) to react. The barium sulfate precipitate generated by the barium chloride solution and the sulfate radical in the brine settles at the bottom of the clarification tube. The upper clarified liquid in the clarification tube enters the collection chamber (5) through the small hole. The clarified liquid in the collection chamber (5) flows into the water distribution tank (12) through the liquid outlet pipe (6).

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