Methanol raw material calcium carbide furnace gas cyanide-containing wastewater treatment equipment and process
By designing equipment and processes for treating cyanide-containing wastewater from calcium carbide furnace gas, methanol feedstock is produced. Ferrous salts are used to generate flocs, which are then separated by precipitation. Combined with dual pH adjustment and reflux pipe design, the problem of catalyst deactivation caused by cyanide in calcium carbide furnace tail gas is solved, achieving efficient wastewater treatment and resource utilization.
Patent Information
- Application Number
- CN202511949283.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-02-24
AI Technical Summary
The exhaust gas from the calcium carbide furnace contains highly toxic cyanide, which causes catalyst deactivation and damage to the preparation equipment. Existing technologies cannot effectively treat cyanide in wastewater, affecting the normal production of methanol preparation units.
A treatment device and process for cyanide-containing wastewater from methanol feedstock calcium carbide furnace gas is adopted, including an inlet tank, a pH adjustment tank, a cyanide removal reaction tank, a flocculation tank, a sedimentation tank, a second pH adjustment tank, and a sludge hopper. Flocculation is generated through ferrous salt reaction and then separated by sedimentation. Combined with dual pH adjustment and reflux pipe design, the wastewater is neutralized.
It effectively reduces the cyanide content in wastewater, improves wastewater utilization, reduces resource waste, and ensures the stable operation of the preparation equipment.
Smart Images
Figure CN121554147A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of calcium carbide furnace gas wastewater treatment technology, and in particular to a treatment device and process for cyanide-containing wastewater from methanol feedstock calcium carbide furnace gas. Background Technology
[0002] The core principle of the calcium carbide furnace tail gas to methanol process is to convert the high-concentration CO in the tail gas into a mixture of hydrogen and carbon monoxide through a catalytic reaction. Methanol is then synthesized from the hydrogen and carbon dioxide under high temperature and pressure. Due to the high temperature and high carbon monoxide concentration inside the calcium carbide furnace, the tail gas contains highly toxic cyanide formed from carbon, hydrogen, and nitrogen. Cyanide easily enters the methanol production process and combines with the active sites of copper-based catalysts to form stable complexes, leading to catalyst deactivation. Furthermore, cyanide readily forms soluble complexes with metals, inducing stress corrosion cracking and damaging the production equipment. The specific cyanide content in the wastewater is as follows: Table 1. Laboratory Analysis Indicators of Calcium Carbide Furnace Gas Wastewater (Emergency Pool)
[0003] Table 2. Water quality test results of wastewater from calcium carbide furnace gas
[0004] As shown in the table above, the cyanide content in the wastewater from the calcium carbide furnace remains higher than the safe value of 10 mg / L under different ammonia nitrogen concentrations and pH values. Therefore, the calcium carbide furnace tail gas needs to be treated to remove cyanide before methanol production.
[0005] The tail gas from the calcium carbide furnace is purified through pretreatment and conversion processes and used as feed gas for the methanol synthesis unit. During normal production, it generates 15 m³ of wastewater per hour. Wastewater from different sources is mixed and temporarily stored in an emergency pool. Due to excessively high cyanide levels in the wastewater, it can cause sludge poisoning in the AO tank biological system of the wastewater treatment unit. Currently, it cannot be recovered and reused through biological treatment, and the untreated wastewater affects the normal production of the calcium carbide furnace gas unit. Summary of the Invention
[0006] One object of the present invention is to provide a treatment device for cyanide-containing wastewater from methanol feedstock calcium carbide furnace gas to effectively solve the problems mentioned in the background art.
[0007] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is as follows: A methanol feedstock calcium carbide furnace gas cyanide-containing wastewater treatment device includes: an inlet tank, a first pH adjustment tank, a cyanide removal reaction tank, a flocculation tank, a sedimentation tank, a second pH adjustment tank, an outlet tank, and a sludge hopper; The inlet of the first pH adjustment tank is connected to the outlet of the inlet tank. The first pH adjustment tank, the cyanide removal reaction tank and the flocculation tank are connected in series. The inlet of the sedimentation tank is connected to the outlet of the flocculation tank. The inlet of the second pH adjustment tank is connected to the outlet of the sedimentation tank. The sludge hopper is detachably connected to the bottom of the sedimentation tank.
[0008] Preferably, the sedimentation tank is internally equipped with a telescopic rod, a sliding rod, and a casing; The telescopic rod is installed on the top of the inner wall of the sedimentation tank, and the sliding rod is fixedly connected to the bottom of the telescopic end of the telescopic rod; The slide bar is movably connected to the inner wall of the sedimentation tank, and the sleeve is fixedly connected to the slide bar.
[0009] Preferably, the sedimentation tank is further provided with a first pusher plate, a second pusher plate, and a connecting block; The first push plate is movably connected to the bottom of the inner wall of the sedimentation tank. A cavity is opened on the side of the top of the first push plate. The second push plate is movably connected in the cavity. The width of the second push plate is the same as that of the first push plate and both are the same as the width of the inner wall of the sedimentation tank. The connecting block is fixedly connected to the top of the second push plate, and the connecting block is movably connected to the slide rod.
[0010] Preferably, the interior of the housing is provided with a roller, a closed roll material, and a limiting slider; The spool is rotatably connected inside the housing, the closed roll is wound up outside the spool, and the closed roll is located above the second push plate in the unfolded state; The outer end of the closed roll extends to the outside of the housing. Multiple limiting sliders are fixedly connected at equal intervals to the side of the closed roll. The limiting sliders are movably connected to the sliding rods. The housing is provided with a spiral track with the same number of turns as the closed roll and movably connected to the limiting sliders.
[0011] Preferably, both the first pH adjustment tank and the second pH adjustment tank are equipped with pH meters for real-time monitoring of the pH value of the wastewater.
[0012] Preferably, the cyanide removal reaction tank, the flocculation tank, and the second pH adjustment tank are all equipped with a stirrer.
[0013] Preferably, a return pipe is provided between the first pH adjustment tank and the output end of the mud hopper.
[0014] Another objective of this invention is to provide a process for treating cyanide-containing wastewater from methanol feedstock calcium carbide furnace gas to effectively solve the problems mentioned in the background art.
[0015] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is as follows: A process for treating cyanide-containing wastewater from methanol feedstock calcium carbide furnace gas includes the following steps: S1: Cyanide-containing wastewater enters the inlet tank for temporary storage, and is then transported to the first pH adjustment tank through pipeline; S2: Add 0.08-0.2 kg / ton of alkaline solution to the first pH adjustment tank to adjust the pH of the cyanide-containing wastewater to the specified value, and then transport it to the cyanide removal reaction tank; S3: Add 2.8-4 kg / ton of ferrous salt to the cyanide removal reaction tank and stir thoroughly to allow it to react fully with the cyanide-containing wastewater to form cyanide-containing reactants and cyanide removal wastewater. Then, transport the reactants and cyanide removal wastewater together to the flocculation tank. S4: Add 0.002 kg / ton of PAM agent to the flocculation tank and stir thoroughly to allow it to react fully with the reactants to form flocs. The flocs and wastewater in the flocculation tank are then transported to the sedimentation tank together. S5: Wastewater and flocs in the sedimentation tank are allowed to settle. The flocs and sludge in the wastewater settle to the bottom and are pushed into the sludge hopper by the first and second push plates. The wastewater above is transported to the second pH adjustment tank. S6: Add alkaline solution to the second pH adjustment tank and stir thoroughly. Adjust the acidic wastewater after adding ferrous salt to neutral and then transport it to the effluent tank to obtain neutral cyanide removal wastewater.
[0016] The beneficial effects of this invention are: 1. This invention reduces the cyanide content in wastewater by adding ferrous salt to the cyanide removal reaction tank to react with cyanide in the wastewater to generate flocs, and then separating the flocs from the water by precipitation. The dual pH adjustment design can adjust both acidic and alkaline wastewater to neutral. The pH value of alkaline wastewater can be adjusted by recirculating acidic wastewater, eliminating the need to add additional acid, reducing consumption, and improving wastewater utilization.
[0017] 2. This invention separates the upper layer of water and the lower layer of sludge that have completed sedimentation in the sedimentation tank by using a sealing roll material. The sealing position can be flexibly adjusted according to the sludge sedimentation height, which can prevent excessive water from being discharged with the sludge and prevent water and sludge from mixing during the sludge discharge process, thereby improving wastewater utilization and reducing waste. Attached Figure Description
[0018] Figure 1 This is a schematic diagram of the equipment and process for treating cyanide-containing wastewater from the calcium carbide furnace gas used as methanol feedstock. Figure 2 This is a schematic diagram of the internal structure of the sedimentation tank in the methanol feedstock calcium carbide furnace gas cyanide wastewater treatment equipment and process. Figure 3 This is a schematic diagram of the internal structure of the casing of the methanol feedstock calcium carbide furnace gas cyanide wastewater treatment equipment and process. Figure 4 This is a schematic diagram of the pusher plate structure of the methanol feedstock calcium carbide furnace gas cyanide-containing wastewater treatment equipment and process.
[0019] Explanation of reference numerals in the attached drawings: 1. Inlet tank; 2. First pH adjustment tank; 3. Cyanide removal reaction tank; 4. Flocculation tank; 5. Sedimentation tank; 51. Telescopic rod; 52. Sliding rod; 53. Shell; 531. Roller; 532. Sealing roll material; 533. Limiting slider; 54. First push plate; 55. Second push plate; 56. Connecting block; 6. Second pH adjustment tank; 7. Outlet tank; 8. Sludge hopper. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.
[0021] In the description of this application, it should be noted that the terms "inner" and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.
[0022] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "setup" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.
[0023] This application designs a device and process for treating cyanide-containing wastewater from methanol feedstock calcium carbide furnace gas, as shown in the attached document. Figure 1-4 As shown, the equipment includes: inlet tank 1, first pH adjustment tank 2, cyanide removal reaction tank 3, flocculation tank 4, sedimentation tank 5, second pH adjustment tank 6, outlet tank 7, and sludge hopper 8. The inlet of the first pH adjustment tank 2 is connected to the outlet of the inlet tank 1. The first pH adjustment tank 2, the cyanide removal reaction tank 3 and the flocculation tank 4 are connected in series. The inlet of the sedimentation tank 5 is connected to the outlet of the flocculation tank 4. The inlet of the second pH adjustment tank 6 is connected to the outlet of the sedimentation tank 5. The sludge hopper 8 is detachably connected to the bottom of the sedimentation tank 5. The bottom of the sedimentation tank 5 has an outlet that communicates with the sludge hopper 8 for discharging sludge. The sludge hopper 8 is used to collect flocs produced by the cyanide removal reaction and sludge in the sewage.
[0024] Furthermore, the sedimentation tank 5 is internally equipped with a telescopic rod 51, a sliding rod 52, and a casing 53; The telescopic rod 51 is installed on the top of the inner wall of the sedimentation tank 5, and the sliding rod 52 is fixedly connected to the bottom of the telescopic end of the telescopic rod 51. A sensor is installed at the bottom of the sliding rod 52 to detect the sedimentation height of the sludge. The slide bar 52 is movably connected to the inner wall of the sedimentation tank 5, and the casing 53 is fixedly connected to the slide bar 52.
[0025] Furthermore, the sedimentation tank 5 is also equipped with a first push plate 54, a second push plate 55, and a connecting block 56. The first push plate 54 is movably connected to the bottom of the inner wall of the sedimentation tank 5. A cavity is opened on the side of the top of the first push plate 54. The second push plate 55 is movably connected in the cavity. The second push plate 55 and the first push plate 54 have the same width and are both the same as the width of the inner wall of the sedimentation tank 5. The sludge below the sedimentation tank 5 can be completely pushed to the outlet to avoid leakage. The connecting block 56 is fixedly connected to the top of the second push plate 55. The connecting block 56 is movably connected to the slide rod 52. The connecting block 56 and the slide rod 52 form a prior art slide rail structure, which is used to drive the first push plate 54 and the second push plate 55 to move.
[0026] Furthermore, the interior of the housing 53 is provided with a roller 531, a closed roll material 532, and a limiting slider 533; The spool 531 is rotatably connected to the inside of the housing 53. The spool 531 is driven by a motor. The closed roll material 532 is wound up outside the spool 531. In the unfolded state, the closed roll material 532 is located above the second push plate 55. The outer end of the closed roll material 532 extends to the outside of the housing 53. Multiple limiting sliders 533 are fixedly connected at equal intervals to the side of the closed roll material 532. The limiting sliders 533 are movably connected to the sliding rod 52. The housing 53 is provided with a spiral track inside, which has the same number of turns as the closed roll material 532 and is movably connected to the limiting sliders 533. This track is used to limit the closed roll material 532 and keep it in a flat state.
[0027] After the wastewater and cyanide-removed flocs enter the sedimentation tank 5, the sludge settles and the water floats to the surface through sedimentation. After sedimentation, the telescopic rod 51 drives the slide rod 52 to descend, and the slide rod 52 drives the connecting block 56 and the second push plate 55 to descend until the sensor on the slide rod 52 detects contact with the sludge. Therefore, the actual height of the push plate can be adjusted according to the different amounts of sedimented wastewater. Subsequently, the sealing roll 532 is driven to unfold by the roller 531, and is limited by the sliding block 533 sliding along the slide rod 52 until the sealing roll 532 covers the inner wall of the sedimentation tank 5, thereby separating the water layer from the sludge, preventing excessive water from being discharged with the sludge, and preventing water and sludge from mixing during the sludge discharge process, thereby improving wastewater utilization and reducing waste. Then, the connecting block 56 drives the second push plate 55 and the first push plate 54 to move, pushing the sludge under the sealing roll 532 toward the outlet, thereby completing the sludge cleaning.
[0028] Furthermore, both the first pH adjustment tank 2 and the second pH adjustment tank 6 are equipped with pH meters to monitor the pH value of the wastewater in real time.
[0029] Furthermore, agitators are installed inside the cyanide removal reaction tank 3, the flocculation tank 4, and the second pH adjustment tank 6 to ensure that the wastewater reacts fully with the additives.
[0030] Furthermore, the process for treating cyanide-containing wastewater from the methanol feedstock calcium carbide furnace gas includes the following steps: S1: Cyanide-containing wastewater enters the inlet tank 1 for temporary storage, and is then transported to the first pH adjustment tank 2 through a pipeline; S2: Add 0.08-0.2 kg / ton of alkaline solution to the first pH adjustment tank 2 to adjust the pH of the cyanide-containing wastewater to 8, and then transport it to the cyanide removal reaction tank 3; S3: Add 2.8-4 kg / ton of ferrous salt to the cyanide removal reaction tank 3 and stir thoroughly to allow it to react fully with the cyanide-containing wastewater to form cyanide-containing reactants and cyanide-removing wastewater. The reactants and cyanide-removing wastewater are then transported together to the flocculation tank 4. The principle of this reaction is as follows: 6CN - +3Fe 2+ →Fe2[Fe(CN)6]↓; S4: Add 0.002 kg / ton of PAM agent to flocculation tank 4 and stir thoroughly to allow it to react fully with the reactants to form flocs. The flocs and wastewater in flocculation tank 4 are then transported to sedimentation tank 5. S5: Wastewater and flocs in sedimentation tank 5 are allowed to settle. The flocs and sludge in the wastewater settle to the bottom and are pushed into sludge hopper 8 by the first push plate 54 and the second push plate 55. The wastewater above is transported to the inside of the second pH adjustment tank 6. S6: Add alkaline solution to the second pH adjustment tank 6 and stir thoroughly. Adjust the acidic wastewater after adding ferrous salt to neutral and then transport it to the effluent tank 7 to obtain neutral cyanide removal wastewater.
[0031] Furthermore, a return pipe is installed between the output end of the first pH adjustment tank 2 and the sludge hopper 8. The return pipe is used to return the acidic wastewater mixed with the flocs containing the reagents in the sludge to the first pH adjustment tank. When the wastewater is alkaline, the pH value can be adjusted directly using the return water without adding acid separately. This makes full use of the wastewater with pH changes during production to reduce the salt content in the wastewater and allows for the recovery of wastewater and reagents in the sludge.
[0032] The cyanide content of the wastewater after cyanide removal treatment is as follows:
[0033] As shown in the table above, the cyanide removal rate of the methanol feedstock calcium carbide furnace gas cyanide wastewater treatment process can stably reach more than 97%. The maximum cyanide removal rate and the lowest effluent turbidity are achieved when the reflux ratio is >0.35. Therefore, the wastewater reflux through the reflux pipe can maximize the removal of cyanide in the wastewater.
[0034] The above embodiments are only some embodiments of the present invention, and not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.
Claims
1. A device for treating cyanide-containing wastewater from methanol feedstock calcium carbide furnace gas, characterized in that: include: Inlet tank (1), first pH adjustment tank (2), cyanide removal reaction tank (3), flocculation tank (4), sedimentation tank (5), second pH adjustment tank (6), outlet tank (7), sludge hopper (8); The inlet of the first pH adjustment tank (2) is connected to the outlet of the inlet tank (1). The first pH adjustment tank (2), the cyanide removal reaction tank (3) and the flocculation tank (4) are connected in series. The inlet of the sedimentation tank (5) is connected to the outlet of the flocculation tank (4). The inlet of the second pH adjustment tank (6) is connected to the outlet of the sedimentation tank (5). The sludge hopper (8) is detachably connected to the bottom of the sedimentation tank (5).
2. The methanol feedstock calcium carbide furnace gas cyanide-containing wastewater treatment equipment according to claim 1, characterized in that: The sedimentation tank (5) is equipped with a telescopic rod (51), a sliding rod (52), and a casing (53). The telescopic rod (51) is installed on the top of the inner wall of the sedimentation tank (5), and the sliding rod (52) is fixedly connected to the bottom of the telescopic end of the telescopic rod (51); The slide bar (52) is movably connected to the inner wall of the sedimentation tank (5), and the casing (53) is fixedly connected to the slide bar (52).
3. The methanol feedstock calcium carbide furnace gas cyanide-containing wastewater treatment equipment according to claim 2, characterized in that: The sedimentation tank (5) is also equipped with a first push plate (54), a second push plate (55), and a connecting block (56). The first push plate (54) is movably connected to the bottom of the inner wall of the sedimentation tank (5). A cavity is opened on the side of the top of the first push plate (54). The second push plate (55) is movably connected in the cavity. The second push plate (55) has the same width as the first push plate (54) and both have the same width as the inner wall of the sedimentation tank (5). The connecting block (56) is fixedly connected to the top of the second push plate (55), and the connecting block (56) is movably connected to the slide rod (52).
4. The methanol feedstock calcium carbide furnace gas cyanide-containing wastewater treatment equipment according to claim 3, characterized in that: The casing (53) is provided with a roller (531), a closed roll material (532), and a limiting slider (533) inside. The spool (531) is rotatably connected to the inside of the housing (53), the closed roll (532) is wound up outside the spool (531), and the closed roll (532) is located above the second push plate (55) in the unfolded state; The outer end of the closed roll (532) extends to the outside of the shell (53). Multiple limiting sliders (533) are fixedly connected at equal intervals to the side of the closed roll (532). The limiting sliders (533) are movably connected to the slide rod (52). The shell (53) is provided with a spiral track inside, which has the same number of turns as the closed roll (532) and is movably connected to the limiting sliders (533).
5. The methanol feedstock calcium carbide furnace gas cyanide-containing wastewater treatment equipment according to claim 1, characterized in that: Both the first pH adjustment tank (2) and the second pH adjustment tank (6) are equipped with pH detectors to detect the pH value of the wastewater in real time.
6. The methanol feedstock calcium carbide furnace gas cyanide-containing wastewater treatment equipment according to claim 1, characterized in that: Agitators are installed inside the cyanide removal reaction tank (3), the flocculation tank (4), and the second pH adjustment tank (6).
7. The methanol feedstock calcium carbide furnace gas cyanide-containing wastewater treatment equipment according to claim 1, characterized in that: A return pipe is provided between the output end of the first pH adjustment tank (2) and the mud hopper (8).
8. The process for treating cyanide-containing wastewater from methanol feedstock calcium carbide furnace gas according to claim 4, characterized in that: Includes the following steps: S1: The cyanide-containing wastewater enters the inlet tank (1) for temporary storage, and is then transported to the first pH adjustment tank (2) through a pipeline. S2: Add 0.08-0.2 kg / ton of alkaline solution to the first pH adjustment tank (2) to adjust the pH of the cyanide-containing wastewater to 8, and then transport it to the cyanide removal reaction tank (3). S3: Add 2.8-4 kg / ton of ferrous salt to the cyanide removal reaction tank (3) and stir it thoroughly so that it reacts fully with the cyanide-containing wastewater to form cyanide-containing reactants and cyanide removal wastewater. Then, transport the reactants and cyanide removal wastewater together to the flocculation tank (4). S4: Add 0.002 kg / ton of PAM agent to the flocculation tank (4) and stir it thoroughly so that it reacts fully with the reactants to form flocs. The flocs and the wastewater in the flocculation tank (4) are transported to the sedimentation tank (5). S5: Wastewater and flocs in sedimentation tank (5) are allowed to settle. The flocs and sludge in the wastewater settle to the bottom and are pushed into the sludge hopper (8) by the first push plate (54) and the second push plate (55). The wastewater above is transported to the inside of the second pH adjustment tank (6). S6: Add alkaline solution to the second pH adjustment tank (6) and stir thoroughly. Adjust the acidic wastewater after adding ferrous salt to neutral and then transport it to the effluent tank (7) to obtain neutral cyanide removal wastewater.