A sodium dichloroisocyanurate production wastewater treatment device

Abstract

The utility model belongs to production wastewater treatment technical field discloses a kind of sodium dichloroisocyanurate production wastewater treatment devices, including mother liquor storage tank and dilute hydrochloric acid storage tank, further including mixer, dechlorination tank, vacuum circulating pump, first vacuum circulating tower and dechlorination wastewater storage tank, the liquid inlet of mixer is connected with the outlet of mother liquor storage tank and dilute hydrochloric acid storage tank respectively, the liquid outlet of mixer is connected with the top liquid inlet of dechlorination tank, the bottom liquid outlet of dechlorination tank is connected with the side liquid inlet of first vacuum circulating tower by vacuum circulating pump, the bottom liquid outlet of first vacuum circulating tower is connected with the top liquid inlet of dechlorination tank, and the top gas outlet of dechlorination tank and first vacuum circulating tower is connected with chlorine negative pressure pipeline.The present application first uses dilute hydrochloric acid to acidify mother liquor, and adopts vacuum dechlorination to recover chlorine gas, so that subsequent sodium hydroxide neutralization treatment can realize the recovery of cyanuric acid, greatly reduces the processing cost, and has good popularization value.

Description

Technical Field

[0001] This utility model belongs to the field of industrial wastewater treatment technology, specifically relating to a device for treating wastewater from sodium dichloroisocyanurate production. Background Technology

[0002] Sodium dichloroisocyanurate (C3O3N3Cl2Na, abbreviated as DCCNa) is an oxidizing disinfectant, commercially known as Dichloroisocyanurate. When produced using the chlorination process, chlorine gas and calcium salt slurry are used as the main raw materials. A countercurrent chlorination reaction produces dichloroisocyanuric acid, which is then neutralized with sodium hydroxide to obtain sodium dichloroisocyanurate. The calcium salt slurry is a suspension formed by the chemical reaction of calcium powder, cyanuric acid, and water in a certain proportion. To obtain high-purity solid dichloroisocyanuric acid, the suspension after the chlorination reaction needs to be centrifuged and dehydrated. However, the mother liquor produced by centrifugation contains a large amount of chlorine gas, a certain concentration of dichloroisocyanuric acid, and some unreacted cyanuric acid. This mother liquor is acidic, making direct wastewater treatment difficult. The conventional method for treating the mother liquor is to directly add a large amount of reducing agent (sodium sulfite, sodium hydroxide) to reduce it to neutral (containing monosodium cyanurate, sodium sulfate, and sodium chloride). This method is costly and results in the inability to recover the cyanuric acid from the mother liquor, leading to resource waste. Summary of the Invention

[0003] This invention addresses the technical problems of high treatment costs and inability to recover cyanuric acid in sodium dichloroisocyanurate production wastewater by providing a sodium dichloroisocyanurate production wastewater treatment device. The device first acidifies the centrifuged dehydration mother liquor with dilute hydrochloric acid, then uses vacuum dechlorination to recover chlorine gas. This allows for the recovery of cyanuric acid with only sodium hydroxide neutralization, resulting in low-concentration cyanuric acid wastewater, significantly reducing treatment costs and possessing good potential for widespread application.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A wastewater treatment device for sodium dichloroisocyanurate production includes a mother liquor storage tank and a dilute hydrochloric acid storage tank, as well as a mixer, a dechlorination tank, a vacuum circulation pump, a first vacuum circulation tower, and a dechlorination wastewater storage tank. The liquid inlet of the mixer is connected to the outlets of the mother liquor storage tank and the dilute hydrochloric acid storage tank, respectively. The liquid outlet of the mixer is connected to the top liquid inlet of the dechlorination tank. The bottom liquid outlet of the dechlorination tank is connected to the side liquid inlet of the first vacuum circulation tower via the vacuum circulation pump. The bottom liquid outlet of the first vacuum circulation tower is connected to the top liquid inlet of the dechlorination tank. The top gas outlets of the dechlorination tank and the first vacuum circulation tower are connected to a chlorine negative pressure pipeline. The side overflow outlet of the dechlorination tank is connected to the top liquid inlet of the dechlorination wastewater storage tank.

[0005] Furthermore, the first vacuum circulation tower is equipped with multiple liquid distributors, and the side liquid inlet of the first vacuum circulation tower is connected to each liquid distributor.

[0006] Furthermore, pipe sights are installed on the pipe between the bottom liquid outlet of the first vacuum circulation tower and the top liquid inlet of the dechlorination tank, and on the pipe between the side overflow outlet of the dechlorination tank and the top liquid inlet of the dechlorination wastewater storage tank.

[0007] Furthermore, two dechlorination tanks, one vacuum circulation pump, and one first vacuum circulation tower are provided, one for use and one for standby, and each dechlorination tank is equipped with a stirrer.

[0008] Furthermore, the device of this utility model also includes a second vacuum circulation tower. The bottom liquid outlet of the dechlorination wastewater storage tank is connected to the side inlet of the second vacuum circulation tower through a wastewater pump. The bottom liquid outlet of the second vacuum circulation tower is connected to the top liquid inlet of the dechlorination wastewater storage tank. The top gas outlet of the second vacuum circulation tower is connected to a chlorine negative pressure pipeline.

[0009] Furthermore, the second vacuum circulation tower is equipped with multiple liquid distributors, and the side liquid inlet of the second vacuum circulation tower is connected to each liquid distributor.

[0010] Furthermore, a pipe sight is installed on the pipe between the bottom liquid outlet of the second vacuum circulation tower and the top liquid inlet of the dechlorination wastewater storage tank.

[0011] Compared with the prior art, the beneficial effects of this utility model are as follows: This invention addresses the production wastewater from sodium dichloroisocyanurate. First, the mother liquor is acidified by centrifugation and dehydration with dilute hydrochloric acid. The dilute hydrochloric acid and dichloroisocyanuric acid in the mother liquor react fully to generate cyanuric acid and chlorine gas. Vacuum dechlorination is then used to allow a large amount of chlorine gas to be recycled through a negative pressure chlorine gas pipeline. This allows for the recovery of cyanuric acid through subsequent neutralization with sodium hydroxide, resulting in low-concentration cyanuric acid wastewater. This approach ensures that the mother liquor meets treatment standards while avoiding waste of raw materials (cyanuric acid) in the mother liquor, achieving environmentally friendly production, significantly reducing treatment costs, and possessing significant potential for widespread application. Attached Figure Description

[0012] Figure 1 This is a schematic diagram of the wastewater treatment device for sodium dichloroisocyanurate production according to this utility model.

[0013] The following labels are used in the attached diagram: 1 is the mother liquor storage tank, 2 is the dilute hydrochloric acid storage tank, 3 is the mixer, 4 is the dechlorination tank, 5 is the first vacuum circulation tower, 6 is the chlorine negative pressure pipeline, 7 is the pipeline sight glass, 8 is the vacuum circulation pump, 9 is the dechlorination wastewater storage tank, 10 is the second vacuum circulation tower, and 11 is the wastewater pump. Detailed Implementation

[0014] The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of protection of the present invention.

[0015] like Figure 1 As shown, this utility model discloses a wastewater treatment device for sodium dichloroisocyanurate production, including a mother liquor storage tank 1 and a dilute hydrochloric acid storage tank 2, as well as a mixer 3, a dechlorination tank 4, a vacuum circulation pump 8, a first vacuum circulation tower 5, and a dechlorination wastewater storage tank 9. The liquid inlet of the mixer 3 is connected to the outlets of the mother liquor storage tank 1 and the dilute hydrochloric acid storage tank 2, respectively. The liquid outlet of the mixer 3 is connected to the top liquid inlet of the dechlorination tank 4. The bottom liquid outlet of the dechlorination tank 4 is connected to the side liquid inlet of the first vacuum circulation tower 5 through the vacuum circulation pump 8. The bottom liquid outlet of the first vacuum circulation tower 5 is connected to the top liquid inlet of the dechlorination tank 4. The top gas outlets of the dechlorination tank 4 and the first vacuum circulation tower 5 are connected to a chlorine negative pressure pipeline 6. The side overflow outlet of the dechlorination tank 4 is connected to the top liquid inlet of the dechlorination wastewater storage tank 9.

[0016] like Figure 1 As shown, the first vacuum circulation tower 5 is equipped with four liquid distributors. The side liquid inlet of the first vacuum circulation tower 5 is connected to each liquid distributor. The liquid distributors increase the residence time of the liquid in the first vacuum circulation tower 5, which is beneficial for the overflow of chlorine gas from the liquid. The overflowed chlorine gas is recovered and reused through the chlorine gas negative pressure pipeline 6. Furthermore, a flow meter can be installed at the outlet of the vacuum circulation pump 8 to ensure that the liquid enters the first vacuum circulation tower 5 evenly.

[0017] like Figure 1 As shown, pipe sights 7 are installed on the pipe between the bottom liquid outlet of the first vacuum circulation tower 5 and the top liquid inlet of the dechlorination tank 4, and on the pipe between the side overflow outlet of the dechlorination tank 4 and the top liquid inlet of the dechlorination wastewater storage tank 9, so as to facilitate observation of the liquid movement in each device.

[0018] To increase the processing capacity of the unit or to ensure uninterrupted production during maintenance, two dechlorination tanks 4, two vacuum circulation pumps 8, and two first vacuum circulation towers 5 are installed. Each dechlorination tank 4 is equipped with an agitator. The dechlorination tank 4 is divided into dechlorination tank A and dechlorination tank B. The first vacuum circulation pump 8 is divided into first vacuum circulation pump A and first vacuum circulation pump B. The first vacuum circulation tower 5 is divided into first vacuum circulation tower A and first vacuum circulation tower B. Dechlorination tank A, first vacuum circulation pump A, and first vacuum circulation tower A form one group, while dechlorination tank B, first vacuum circulation pump B, and first vacuum circulation tower B form another group. One group of equipment is in use and the other is on standby.

[0019] This utility model device also includes a second vacuum circulation tower 10. The bottom liquid outlet of the dechlorination wastewater storage tank 9 is connected to the side inlet of the second vacuum circulation tower 10 via a wastewater pump 11. The bottom liquid outlet of the second vacuum circulation tower 10 is connected to the top liquid inlet of the dechlorination wastewater storage tank 9. The top gas outlet of the second vacuum circulation tower 10 is connected to the chlorine negative pressure pipeline 6. In addition, to increase the processing capacity and further dechlorination effect, three dechlorination wastewater storage tanks 9 can be set. The three dechlorination wastewater storage tanks 9 are connected in series via overflow ports. The first two dechlorination wastewater storage tanks 9 are connected to the side inlet of the second vacuum circulation tower 10 via the wastewater pump 11. The bottom liquid outlet of the second vacuum circulation tower 10 is connected to the top liquid inlet of the first two dechlorination wastewater storage tanks 9. The bottom liquid outlet of the last dechlorination wastewater storage tank 9 is connected to the neutralization process.

[0020] like Figure 1 As shown, the second vacuum circulation tower 10 is equipped with four liquid distributors. The side liquid inlet of the second vacuum circulation tower 10 is connected to each liquid distributor. The liquid distributor can increase the residence time of the liquid in the second vacuum circulation tower 10, which is conducive to the overflow of chlorine gas in the liquid. The overflowed chlorine gas is recovered and reused through the chlorine gas negative pressure pipeline 6.

[0021] like Figure 1 As shown, a pipe sight is installed on the pipe between the bottom liquid outlet of the second vacuum circulation tower 10 and the top liquid inlet of the dechlorination wastewater storage tank 9 to facilitate observation of the liquid movement in each device.

[0022] In actual operation, a vacuum gauge is installed on the gas outlet pipe at the top of the dechlorination tank 4, and a pressure gauge is installed on the liquid outlet of the vacuum circulation pump 8. Before liquid is introduced into the dechlorination tank 4, the negative pressure system connected to the chlorine negative pressure pipe 6 must be turned on, and the stirrer inside the dechlorination tank 4 must be turned on. The dechlorination tank 4 and the first vacuum circulation tower 5 are kept under negative pressure through the chlorine negative pressure pipe 6. When the vacuum gauge detection system reaches the set index, the mother liquor in the mother liquor storage tank 1 and the dilute hydrochloric acid in the dilute hydrochloric acid storage tank 2 simultaneously enter the mixer 3. The liquid outlet pipe of the mixer 3 is directly connected to the bottom of the dechlorination tank 4. The dilute hydrochloric acid and dichloroisocyanuric acid in the mother liquor react fully to generate cyanuric acid and chlorine gas. A small amount of chlorine gas overflows and enters the chlorine negative pressure pipe. The liquid level in the dechlorination tank 4 is observed to overflow from the side overflow port through the pipe sight glass 7. The vacuum circulation pump 8 is then turned on to pump the liquid in the dechlorination tank 4 into the first vacuum circulation tower 5. A large amount of overflowing chlorine gas in the first vacuum circulation tower 5 enters the chlorine negative pressure pipe 6 for recycling. The dechlorinated liquid at the bottom of the first vacuum circulation tower 5 enters the dechlorination tank 4. As the liquid level in the dechlorination tank 4 rises, the dechlorinated liquid flows into the dechlorination wastewater storage tank 9 through the side overflow port of the dechlorination tank 4. This cycle can greatly reduce the dechlorination time and reduce chlorine consumption. In addition, the wastewater in the dechlorination wastewater storage tank 9 also contains a small amount of chlorine. Connecting to the second vacuum circulation tower 10 can further dechlorinate the wastewater, greatly reducing the residual chlorine content in the cyanuric acid-containing wastewater coming out of the dechlorination wastewater storage tank 9. In the subsequent neutralization process, hydrogen peroxide is first used to reduce the residual free chlorine, and then sodium hydroxide is used to neutralize the cyanuric acid in the wastewater into sodium cyanurate, which enters the sedimentation tank. In the sedimentation tank, due to the low solubility of cyanuric acid and sodium cyanurate in water, they precipitate out, allowing the cyanuric acid to be recovered. At the same time, a low concentration of cyanuric acid wastewater is formed, reducing the difficulty of wastewater treatment and reducing the use of reducing agent sodium sulfite, thus reducing the cost of wastewater treatment.

[0023] The embodiments described above are merely preferred embodiments of this utility model and are only used to explain this utility model. They are not intended to limit the scope of implementation of this utility model. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of this utility model should be included within the scope of the patent application of this utility model.

Claims

1. A wastewater treatment device for sodium dichloroisocyanurate production, comprising a mother liquor storage tank (1) and a dilute hydrochloric acid storage tank (2), characterized in that, It also includes a mixer (3), a dechlorination tank (4), a vacuum circulation pump (8), a first vacuum circulation tower (5), and a dechlorination wastewater storage tank (9). The liquid inlet of the mixer (3) is connected to the outlet of the mother liquor storage tank (1) and the dilute hydrochloric acid storage tank (2), respectively. The liquid outlet of the mixer (3) is connected to the top liquid inlet of the dechlorination tank (4). The bottom liquid outlet of the dechlorination tank (4) is connected to the side liquid inlet of the first vacuum circulation tower (5) through the vacuum circulation pump (8). The bottom liquid outlet of the first vacuum circulation tower (5) is connected to the top liquid inlet of the dechlorination tank (4). The top gas outlets of the dechlorination tank (4) and the first vacuum circulation tower (5) are connected to the chlorine negative pressure pipeline (6). The side overflow outlet of the dechlorination tank (4) is connected to the top liquid inlet of the dechlorination wastewater storage tank (9).

2. The sodium dichloroisocyanurate production wastewater treatment device according to claim 1, characterized in that, The first vacuum circulation tower (5) is equipped with multiple liquid distributors, and the side liquid inlet of the first vacuum circulation tower (5) is connected to each liquid distributor.

3. The sodium dichloroisocyanurate production wastewater treatment device according to claim 1, characterized in that, Pipe sights (7) are installed on the pipe between the bottom liquid outlet of the first vacuum circulation tower (5) and the top liquid inlet of the dechlorination tank (4), and on the pipe between the side overflow outlet of the dechlorination tank (4) and the top liquid inlet of the dechlorination wastewater storage tank (9).

4. The wastewater treatment device for sodium dichloroisocyanurate production according to claim 1, characterized in that, Two dechlorination tanks (4), two vacuum circulation pumps (8), and two first vacuum circulation towers (5) are provided, and each dechlorination tank (4) is equipped with a stirrer.

5. The wastewater treatment device for sodium dichloroisocyanurate production according to claim 1, characterized in that, It also includes a second vacuum circulation tower (10), the bottom liquid outlet of the dechlorination wastewater storage tank (9) is connected to the side inlet of the second vacuum circulation tower (10) through a wastewater pump (11), the bottom liquid outlet of the second vacuum circulation tower (10) is connected to the top liquid inlet of the dechlorination wastewater storage tank (9), and the top gas outlet of the second vacuum circulation tower (10) is connected to the chlorine negative pressure pipeline (6).

6. The sodium dichloroisocyanurate production wastewater treatment device according to claim 5, characterized in that, The second vacuum circulation tower (10) is equipped with multiple liquid distributors, and the side liquid inlet of the second vacuum circulation tower (10) is connected to each liquid distributor.

7. The sodium dichloroisocyanurate production wastewater treatment device according to claim 5, characterized in that, A pipe sight is installed on the pipe between the bottom liquid outlet of the second vacuum circulation tower (10) and the top liquid inlet of the dechlorination wastewater storage tank (9).

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