An apparatus for recovering sodium bromide from carbazole alkylation waste alkaline solution

Abstract

This utility model relates to a device for recovering sodium bromide from carbazole alkylation waste alkaline solution, comprising a crystallizer, a separator, and a connecting pipe. The crystallizer is vertically arranged, with a first inlet at the top and a discharge outlet at the bottom. An internal thermometer and temperature control mechanism are installed, with the thermometer's measuring point near the discharge outlet. The separator includes a second inlet, a filter cake outlet, and a filtrate outlet. A vibrating screen with a pore size of 50-100 μm is installed between the second inlet and the filter cake outlet, and a ceramic membrane filter with a particle size >1 μm is installed between the filter cake outlet and the filtrate outlet. The connecting pipe connects the discharge outlet and the second inlet, and is equipped with an electrically controlled valve that controls its opening and closing based on the signal measured by the thermometer. This device can precisely control the temperature inside the crystallizer, thereby rapidly crystallizing sodium bromide, which is then separated by the separator, increasing the separation speed of sodium bromide.

Description

Technical Field

[0001] This utility model relates to the field of waste liquid treatment technology, and in particular to a device for recovering sodium bromide from carbazole alkylation waste alkaline solution. Background Technology

[0002] The waste alkaline solution produced after the carbazole alkylation reaction typically contains high concentrations of sodium bromide (NaBr), unreacted organic matter (such as carbazole derivatives), byproducts, and strongly alkaline substances (such as NaOH). Direct discharge of this type of waste liquid not only wastes bromine resources but also causes serious harm to the ecological environment due to its high salt content, high alkalinity, and organic pollutants. A crystallization separation process is usually used to separate the sodium bromide and waste alkaline water for recycling.

[0003] Cooling crystallization technology is one of the core processes for solute separation and purification in the chemical, pharmaceutical, food, and environmental protection fields. Its principle is to control the cooling rate and temperature gradient of the solution to induce the solute to precipitate in crystal form, thereby achieving efficient recovery of the target product or removal of impurities. Existing cooling crystallization equipment typically employs indirect heat exchange (such as jacket cooling or coil cooling) or direct cooling (such as refrigerant injection) to cool the solution, and is classified into batch, continuous, or semi-continuous operation modes according to process requirements.

[0004] Existing cooling crystallization equipment mainly includes internal circulation cooling crystallizers and external circulation cooling crystallizers. Internal circulation cooling crystallizers have a small heat exchange area and limited heat exchange capacity. Their surfaces are easily covered by crystals, and scaling reduces heat transfer efficiency. Furthermore, they require manual cleaning after shutdown, resulting in high maintenance costs. While external circulation cooling crystallizers have a large heat transfer coefficient and variable heat exchange area, they require the selection of a suitable circulation pump to prevent wear and breakage of suspended crystals. Additionally, external heat exchangers are more prone to scaling, which affects their performance.

[0005] Chinese patent CN215538560U discloses a high-efficiency cooling crystallization vessel, comprising a vessel body, a jacket, a rotating drum, a drive mechanism, a stirrer, a cooling cylinder, and a cooling coil. The jacket is used to heat the liquid inside the vessel, while the cooling cylinder remains stationary within the rotating drum. The cooling coil cools the interior of the cooling cylinder. The drive mechanism drives the rotating drum and the stirrer to rotate, thereby stirring the liquid in the outer cavity of the vessel. The stirrer has a bottom mounting plate at the bottom and a cylinder wall scraper on the side, which can reduce scaling on the cylinder wall, but increases energy consumption.

[0006] Therefore, it is necessary to improve the equipment structure to solve the above problems. Utility Model Content

[0007] The main objective of this invention is to provide a device for recovering sodium bromide from carbazole alkylation waste alkaline solution, which can precisely control the temperature inside the crystallization tank, thereby enabling rapid crystallization of sodium bromide, followed by separation by a separator, thus improving the separation speed of sodium bromide.

[0008] This utility model achieves the above-mentioned objective through the following technical solution: a device for recovering sodium bromide from carbazole alkylation waste alkaline solution, comprising a crystallizer, a separator, and a connecting pipe; The crystallization tank is vertically arranged, with a first feed inlet at the top and a discharge outlet at the bottom. It is equipped with a thermometer and a temperature control mechanism inside, with the thermometer's measuring point close to the discharge outlet. The separator includes a second feed inlet, a filter cake outlet, and a filtrate outlet. A vibrating screen with a pore size of 50-100 μm is provided between the second feed inlet and the filter cake outlet, and a ceramic membrane filter with a particle size of >1 μm is provided between the filter cake outlet and the filtrate outlet. The connecting pipe connects the outlet and the second inlet. An electrically controlled valve is provided on the connecting pipe, and the electrically controlled valve controls the switch according to the signal measured by the thermometer.

[0009] Specifically, the temperature control mechanism includes a jacket disposed on the side wall of the crystallization tank, with water entering at the upper part and exiting at the lower part.

[0010] Furthermore, the temperature control mechanism also includes a cooling coil located inside the crystallization tank. The inlet and outlet of the cooling coil are both located at the top of the crystallization tank. The thermometer is surrounded by the cooling coil, and the flow rate of the internal circulating cooling water through the cooling coil is controlled according to the temperature signal collected by the thermometer.

[0011] Furthermore, the cooling coil is a double spiral coil.

[0012] Specifically, the outer wall of the crystallization tank is provided with at least one pair of lifting lugs.

[0013] Specifically, the separator is arranged horizontally, with the second feed inlet located on one side of the separator, the filtrate outlet located on the opposite side of the second feed inlet, and the filter cake outlet located at the bottom of the separator.

[0014] Furthermore, the lower part of the separator is provided with a pair of fixed supports, and the filter cake outlet is located between the two fixed supports.

[0015] The beneficial effects of this utility model's technical solution are: This equipment can precisely control the temperature inside the crystallizer, thereby enabling sodium bromide to crystallize rapidly, and then separate it through a separator, thus increasing the separation speed of sodium bromide. Attached Figure Description

[0016] Figure 1 This is a simplified piping diagram of an apparatus for recovering sodium bromide from carbazole alkylation waste alkaline solution, as illustrated in this example. Figure 2 This is a cross-sectional view of the crystallization tank; Figure 3 This is a cross-sectional view of the separator.

[0017] The numbers in the diagram represent: 1-Crystallization tank, 11-First feed inlet, 12-Discharge outlet, 13-Thermometer, 14-Jacket, 15-Cooling coil, 16-Lifting lug bracket; 2-Separator, 21-Second feed inlet, 22-Filter cake outlet, 23-Filtrate outlet, 24-Vibrating screen, 25-Ceramic membrane filter, 26-Fixed bracket; 3-Connecting pipe, 31-Electrically controlled valve. Detailed Implementation

[0018] The present invention will be further described in detail below with reference to specific embodiments.

[0019] Example: like Figure 1 As shown, the present invention discloses a device for recovering sodium bromide from carbazole alkylation waste alkaline solution, comprising a crystallization tank 1, a separator 2, and a connecting pipe 3.

[0020] The entire device utilizes sodium bromide crystallization at a specific temperature. Crystallization tank 1 controls the temperature of the waste liquid to a state where sodium bromide precipitates while other components do not. Connecting pipe 3 transports the waste liquid containing sodium bromide crystals to separator 2, where the separator retains the sodium bromide crystals, while the remaining waste liquid is sent to other equipment for further processing.

[0021] like Figure 2 As shown, the crystallization tank 1 is vertically arranged. The upper part of the crystallization tank 1 has a first feed inlet 11, and the bottom has a discharge outlet 12. Inside, there is a thermometer 13 and a temperature control mechanism. The temperature measuring point of the thermometer 13 is close to the discharge outlet 12. The temperature control mechanism includes a jacket 14 located on the side wall of the crystallization tank 1, with water entering at the top and exiting at the bottom. The temperature control mechanism also includes a cooling coil 15 located inside the crystallization tank 1. The inlet and outlet of the cooling coil 15 are both located at the top of the crystallization tank 1. The thermometer 13 is surrounded by the cooling coil 15, and the flow rate of the internal circulating cooling water through the cooling coil 15 is controlled according to the temperature signal collected by the thermometer 13. The cooling coil 15 is a double-spiral coil. At least one pair of lifting lugs 16 are provided on the outer wall of the crystallization tank 1.

[0022] The waste liquid enters the crystallizer 1 through the first inlet 11 and is temperature-controlled by the temperature control mechanism to keep its temperature close to the crystallization temperature of sodium bromide. The jacket 14 is used to control the temperature of the waste liquid near the side wall of the crystallizer 1 to be slightly higher than this crystallization temperature, preventing sodium bromide from agglomerating on the side wall. Therefore, the external circulating cooling water through the jacket 14 only needs to maintain a specific temperature and flow rate. The cooling water in the jacket 14 flows from top to bottom, resulting in low flow resistance. The cooling coil 15 is designed to allow the sodium bromide inside the waste liquid to form small crystals, which can then be filtered out by the separator 2. Compared to a single spiral coil, a double spiral coil has a larger specific surface area, accelerating heat exchange and allowing the waste liquid to cool quickly to a reasonable range that meets crystallization requirements. The waste liquid's exit from the outlet 12 depends primarily on whether the internal temperature has reached a reasonable level; therefore, placing the temperature measuring point within the area surrounded by the cooling coil 15 is appropriate. If the temperature detected by thermometer 13 is higher than the reasonable range, the flow rate of the internal circulating cooling water needs to be increased; if the temperature detected by thermometer 13 is lower than the reasonable range, the flow rate of the internal circulating cooling water needs to be decreased. The lifting lug bracket 16 allows the crystallizer 1 to be suspended and installed at a position relatively high relative to the separator 2.

[0023] like Figure 3 As shown, the separator 2 includes a second feed inlet 21, a filter cake outlet 22, and a filtrate outlet 23. A vibrating screen 24 with a pore size of 50-100 μm is provided between the second feed inlet 21 and the filter cake outlet 22, and a ceramic membrane filter 25 with a particle size >1 μm is provided between the filter cake outlet 22 and the filtrate outlet 23. The separator 2 is horizontally arranged, with the second feed inlet 21 located on one side of the separator 2, the filtrate outlet 23 located on the opposite side of the second feed inlet 21, and the filter cake outlet 22 located at the bottom of the separator 2. A pair of fixed supports 26 are provided at the bottom of the separator 2, and the filter cake outlet 22 is located between the two fixed supports 26.

[0024] The cooled waste liquid needs to pass sequentially through the second inlet 21, the filter cake outlet 22, and the filtrate outlet 23. The vibrating screen 24 traps large particles of impurities, allowing sodium bromide crystals and soluble waste liquid to pass through. The ceramic membrane filter 25 traps sodium bromide crystals, allowing soluble waste liquid to pass through. For the horizontally positioned separator 2, the sodium bromide crystals form a filter cake and fall into the filter cake outlet 22 below, making it less likely to clog the channel and allowing the separator 2 to maintain a relatively high filtration efficiency. The fixed bracket 26 is used to horizontally fix the separator 2 while also providing space below the filter cake outlet 22 for installing pipes.

[0025] like Figure 1 As shown, the connecting pipe 3 connects the discharge port 12 and the second inlet 21. The connecting pipe 3 is equipped with an electric control valve 31, which controls the switch according to the signal measured by the thermometer 13.

[0026] Because filtration is only meaningful when sodium bromide crystallizes, the solenoid valve 31 will not open until the temperature of the waste liquid at the outlet 12, as measured by thermometer 13, reaches a reasonable range.

[0027] The working principle of this equipment is as follows: Waste liquid enters crystallizer 1 through the first inlet 11. Under the monitoring of thermometer 13, the solenoid valve 31 is not opened initially. External circulating cooling water is circulated in jacket 14 to minimize crystal precipitation in the part of the waste liquid close to the side wall of crystallizer 1. At the same time, internal circulating cooling water is circulated in cooling coil 15. The internal circulating cooling water has a lower temperature, which lowers the temperature of the inner part of the waste liquid to below the crystallization temperature of sodium bromide. After the temperature detected by thermometer 13 reaches the standard, solenoid valve 31 is opened, and the crystallized waste liquid is introduced into the second inlet 21 of separator 2 through connecting pipe 3. Vibrating screen 24 will intercept large particles of impurities. Sodium bromide crystals can pass through vibrating screen 24 but cannot pass through ceramic membrane filter screen 25, thus forming a filter cake and being discharged from filter cake outlet 22. The remaining filtrate goes through filtrate outlet 23 to the next device for further processing.

[0028] This equipment can precisely control the temperature inside the crystallizer 1, thereby enabling sodium bromide to crystallize rapidly, and then separate through the separator 2, thus increasing the separation speed of sodium bromide.

[0029] The above descriptions are merely some embodiments of this utility model. For those skilled in the art, various modifications and improvements can be made without departing from the inventive concept of this utility model, and all such modifications and improvements fall within the protection scope of this utility model.

Claims

1. A device for recovering sodium bromide from carbazole alkylation waste alkaline solution, characterized in that: Includes crystallizer, separator, and connecting pipes; The crystallization tank is vertically arranged, with a first feed inlet at the top and a discharge outlet at the bottom. It is equipped with a thermometer and a temperature control mechanism inside, with the thermometer's measuring point close to the discharge outlet. The separator includes a second feed inlet, a filter cake outlet, and a filtrate outlet. A vibrating screen with a pore size of 50-100 μm is provided between the second feed inlet and the filter cake outlet, and a ceramic membrane filter with a particle size of >1 μm is provided between the filter cake outlet and the filtrate outlet. The connecting pipe connects the outlet and the second inlet. An electrically controlled valve is provided on the connecting pipe, and the electrically controlled valve controls the switch according to the signal measured by the thermometer.

2. The equipment for recovering sodium bromide from carbazole alkylation waste alkaline solution according to claim 1, characterized in that: The temperature control mechanism includes a jacket disposed on the side wall of the crystallization tank, with water entering at the upper part and exiting at the lower part.

3. The equipment for recovering sodium bromide from carbazole alkylation waste alkaline solution according to claim 2, characterized in that: The temperature control mechanism also includes a cooling coil located inside the crystallization tank. The inlet and outlet of the cooling coil are both located at the top of the crystallization tank. The thermometer is surrounded by the cooling coil, and the flow rate of the internal circulating cooling water through the cooling coil is controlled according to the temperature signal collected by the thermometer.

4. The equipment for recovering sodium bromide from carbazole alkylation waste alkaline solution according to claim 3, characterized in that: The cooling coil is a double spiral coil.

5. The equipment for recovering sodium bromide from carbazole alkylation waste alkaline solution according to claim 1, characterized in that: The outer wall of the crystallization tank is provided with at least one pair of lifting lugs.

6. The equipment for recovering sodium bromide from carbazole alkylation waste alkaline solution according to claim 1, characterized in that: The separator is horizontally arranged, with the second feed inlet located on one side of the separator, the filtrate outlet located on the opposite side of the second feed inlet, and the filter cake outlet located at the bottom of the separator.

7. The apparatus for recovering sodium bromide from carbazole alkylation waste alkaline solution according to claim 6, characterized in that: The lower part of the separator is provided with a pair of fixed supports, and the filter cake outlet is located between the two fixed supports.

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