Method and system for synergistically regulating low-oil and high-quality tar in coking plant circulating ammonia water

Abstract

This invention discloses a method and system for synergistic regulation of low oil content and high-quality tar in circulating ammonia water of coking plants, belonging to the field of coal chemical tar ammonia water separation and purification technology. The system includes a gas-liquid separation device, a tar ammonia water separation device, a reagent quantitative dosing device, a tar residue draining device, and a control system. The gas-liquid separation device includes a gas-liquid separator, a horizontal tube primary cooler, an upper condensate circulation tank, and a lower condensate circulation tank. The tar ammonia water separation device includes a mechanized tar ammonia water separation tank, a first-stage circulating ammonia water tank, and a second-stage circulating ammonia water tank. The reagent quantitative dosing device includes a multi-point synergistic demulsifier dosing device and a flocculant dosing device. The tar residue draining device includes a liquefaction tank, a grinding pump, a centrifuge, and a slag hopper. The control system includes a hysteresis-stretching interface meter, an automatic regulating valve, and a PLC controller. This invention breaks through the traditional single-improvement mode, forming a systematic solution; it can significantly reduce the oil content of circulating ammonia water and improve tar quality.

Description

Technical Field

[0001] This invention belongs to the field of tar-ammonia water separation and purification technology in the coal chemical coking production process, and relates to a method and system for synergistic regulation of low oil content and high tar in circulating ammonia water in the blast condensation process of coking plants. Background Technology

[0002] In the coking process, high-temperature raw coal gas is condensed by blast furnace to form a mixture containing tar, ammonia water, and tar residue, which then enters a mechanized tar-ammonia water separator (commonly known as a "tar boat") for three-phase separation. This stage is a critical point for coke oven gas purification and by-product recovery, directly affecting tar quality, the cleanliness of circulating ammonia water, and the operational safety of subsequent equipment. However, existing processes suffer from the following common technical bottlenecks: 1. Low precision in oil-water interface control: Oil discharge from the tar boat and tar separator relies on manual experience, resulting in large fluctuations in liquid level (up to 1.0–2.3 m), leading to severe water entrainment in the tar or overflow into the circulating ammonia water system, causing excessive oil content in the circulating ammonia water (exceeding 1000 mg / L), affecting the coke oven spray cooling effect and the heat exchange efficiency of the primary cooler. 2. Separation efficiency is limited by tank structure: Traditional circulating ammonia tanks often use a parallel arrangement of one tar tanker corresponding to one circulating ammonia pipe. The residence time in a single tank is short, and oil droplets are discharged with the water flow before they can fully coalesce and settle. Furthermore, there is a lack of staged settling design, making it easy for suspended solids to back-mix, affecting water quality stability. 3. Difficulty in breaking down emulsified tar: Due to high temperature, high shear, and the presence of surfactants, tar and ammonia form a stable emulsion. Conventional settling is insufficient for demulsification, resulting in a high tar water content (>5%), affecting tar sales prices and deep processing utilization. 4. Lack of systematic reagent application: Demulsifiers are usually only added at the front end of the tar dehydrator, failing to cover the source of emulsification (such as condensate from the primary cooler). This leads to low reagent utilization and unstable demulsification effect. 5. Crude treatment of tar residue: Tar residue is a high-viscosity paste with an oil content as high as 30-40%. Traditionally, it is manually collected and then piled up in the open or simply dried, resulting in VOC emissions, soil pollution, and resource waste.

[0003] The current improvement measures mainly focus on the following aspects: (1) Liquid level monitoring and automatic oil discharge: Some patents disclose the technology of using radar liquid level gauges to monitor the interface of tar tankers, but its accuracy is poor and the control logic is mostly a switch-type control of "high alarm to start valve, low alarm to stop valve", without involving PID closed-loop regulation algorithm, which cannot achieve precise and stable liquid level control; and the control range is wide (such as 1.0-1.8m), and there is still a risk of oil spill or water entrainment. (2) Tank structure improvement: Existing technologies generally adopt the expansion or addition of stirring devices to improve the separation effect, but there is no design to change the parallel connection of circulating ammonia tanks to series connection to achieve staged sedimentation, and there is a lack of systematic optimization of residence time distribution and sedimentation dynamics. (3) Demulsifier application: Existing patents mention adding demulsifiers before the tar dehydrator, but the addition point is single and does not cover the emulsification source such as the condensate of the primary cooler and the inlet of the circulating ammonia pump, which makes it difficult to fundamentally inhibit emulsification formation; there is also no multi-point synergistic dosing strategy and flow linkage control mechanism. (4) Tar residue treatment: Most enterprises still use manual slag removal and drying, failing to achieve full-process automation integration of liquefaction-crushing-centrifugation-drying, and failing to clarify the resource utilization path of the product (such as its use in coal briquettes). The above-mentioned improvement measures (such as liquid level monitoring, local chemical addition, etc.) are all single-link optimizations, lacking process reconstruction and multi-objective collaborative control mechanisms for the entire blower condenser system, and cannot fundamentally solve the contradiction between high oil content in circulating ammonia water and poor tar quality.

[0004] Therefore, there is an urgent need for a systematic solution that integrates structural innovation, intelligent control, chemical engineering and resource recycling to achieve green, efficient and intelligent operation of the blast condensation process in coking plants. Summary of the Invention

[0005] To address the long-standing systemic problems in the blast condensation process of coking plants, such as "high oil content in circulating ammonia water, unstable tar quality, crude oil-water interface control, severe tar emulsification, and difficult tar residue treatment," this invention aims to provide a method and system for the synergistic regulation of low oil content and high-quality tar in circulating ammonia water in coking plants. Specifically, it involves a method and system that achieves the simultaneous production of low oil content in circulating ammonia water and high-quality tar through structural reconstruction, intelligent control, synergistic chemical demulsification, and solid waste resource utilization.

[0006] This invention is the first to integrate four major modules: "Dynamic steady-state control method of oil-water interface based on PID algorithm + innovative series-sequential settling structure of circulating ammonia tank + multi-point collaborative demulsification system covering emulsification source and treatment end + integrated process of tar residue centrifugal deoiling and briquetting raw material conversion", forming a complete technical closed loop, which is suitable for the intelligent upgrading of coke oven gas purification systems in industries such as metallurgy and chemical industry.

[0007] This invention provides a synergistic control system for low oil content and high tar in circulating ammonia water of a coking plant, including a gas-liquid separation device, a tar-ammonia water separation device, a reagent quantitative dosing device, a tar residue draining device, and a PLC control system. The gas-liquid separation device includes a gas-liquid separator, a horizontal tube primary cooler, an upper condensate circulation tank, and a lower condensate circulation tank. One end of the gas-liquid separator is connected to the coke oven, and the other end is connected to the horizontal tube primary cooler. The condensate separated by the gas-liquid separator enters the tar-ammonia-water separation device. The lower condensate circulation tank is connected to the lower circulation pump, forming a circulation loop with the lower section of the horizontal tube primary cooler. The upper condensate circulation tank is connected to the upper circulation pump, forming a circulation loop with the upper section of the horizontal tube primary cooler. Excess condensate enters the tar-ammonia-water separation device. The horizontal tube primary cooler is connected to an electrostatic precipitator and a blower, and the separated coal gas is sent to the ammonium sulfate process. The tar-ammonia water separation device includes a mechanized tar-ammonia water separation tank, a first-stage circulating ammonia water tank, and a second-stage circulating ammonia water tank, forming a staged series sedimentation structure. The second-stage circulating ammonia water tank is connected to a circulating ammonia water pump, which pumps the treated ammonia water into the coke oven for recycling. The mechanized tar-ammonia water separation tank separates tar, ammonia water, and tar residue. Its ammonia water outlet is connected to the first-stage circulating ammonia water tank, its tar outlet is connected to the tar separation tank, and its tar residue outlet is connected to a tar residue draining device. The quantitative dosing device includes a multi-point synergistic demulsifier dosing device and a flocculant dosing device. The demulsifier dosing device is a five-stage demulsifier dosing network covering the source of emulsion formation and the treatment path. Specifically, the dosing points are located at: Point A: the inlet of the circulating ammonia pump, where demulsifier is added to pre-treat the main circulating flow; Point B: the inlet of the condensate pump in the lower section of the horizontal tube primary cooler, where the high-temperature condensate is treated; Point C: the inlet of the condensate pump in the upper section of the horizontal tube primary cooler, where the low-temperature condensate is treated; Point D: the front end of the mechanized tar-ammonia water separator, where enhanced demulsification is achieved; Point E: the top of two first-stage circulating ammonia water tanks (tanks #1 and #2 are connected in series to form a first-secondary system, and tanks #3 and #4 are connected in series to form a first-secondary system) for final demulsification; the flocculant dosing point is located at the front end of the mechanized tar-ammonia water separator. The tar residue draining device includes a liquefaction tank, a grinding pump, a centrifuge, and a slag hopper connected in sequence. The liquefaction tank is connected to a mechanized tar-ammonia water separation tank, and the tar residue enters the liquefaction tank. The tar residue is liquefied with oil in the liquefaction tank, crushed by the grinding pump, separated by the centrifuge, and dried into granules in the slag hopper, which are then sent to the briquetting workshop.

[0008] Control system: includes a hysteresis extensor interface instrument, an automatic regulating valve, a PLC controller, an electrical control panel, and an operating system terminal computer. The hysteresis extensor interface instrument is installed in the mechanized tar-ammonia water separation tank to display the interface position (liquid level) of tar and ammonia water in real time. The liquid level is controlled by adjusting the opening of the automatic regulating valve according to the liquid level change, with a control accuracy of ±2mm.

[0009] Furthermore, the tar-ammonia water separation device is a staged series sedimentation structure of circulating ammonia water tanks, including four circulating ammonia water tanks, which are correspondingly arranged with four mechanized tar-ammonia water separation tanks. This is one of the innovations of the present invention. Specifically, the four mechanized tar-ammonia water separation tanks are arranged in parallel, and the four circulating ammonia water tanks are respectively designated as 1#, 2#, 3#, and 4# circulating ammonia water tanks. Among them, the series-connected 1# and 2# circulating ammonia water tanks are connected in parallel with the series-connected 3# and 4# circulating ammonia water tanks. That is, the series-connected 1# and 2# circulating ammonia water tanks form the first stage and the second stage of circulating ammonia water tanks, respectively, and the series-connected 3# and 4# circulating ammonia water tanks form the second stage of circulating ammonia water tanks. The circulating ammonia tanks are connected in series to form another set of first-stage and second-stage circulating ammonia tanks. The mechanized tar-ammonia separation tank is connected to the first-stage and second-stage circulating ammonia tanks connected in series to achieve staged sedimentation. The operation mode is as follows: the first-stage circulating ammonia tank serves as the main sedimentation zone, undertaking most of the functions of oil droplet separation and suspended solids sedimentation; the second-stage circulating ammonia tank serves as a buffer and pressure stabilization zone to ensure stable effluent water quality. Oil discharge valves are installed at the bottom of both the first-stage and second-stage circulating ammonia tanks. The oil and slag discharge valves are opened according to the sediment thickness or a timed program to prevent sediment back-mixing from affecting the separation efficiency.

[0010] Furthermore, the second-stage circulating ammonia tank mainly discharges ammonia water, and an oil drain valve is installed at the bottom (to discharge the small amount of tar that settles to the bottom of the tank). The second-stage circulating ammonia water tank is connected to a circulating ammonia water pump, and an oil removal filter is installed on the outlet pipe of the circulating ammonia water pump. Most of the filtered ammonia water is sent to the coke oven for circulating spraying, and the excess ammonia water is sent to the ammonium sulfate ammonia stripping system through the surplus ammonia water tank.

[0011] Furthermore, each drug dispensing point is equipped with a high-precision metering pump and flow meter, and the dosage is adjusted proportionally according to the corresponding fluid flow rate to create a gradient demulsification effect.

[0012] The tar residue draining device is a fully automatic tar residue draining and resource recovery system. The tar residue draining device is built at the rear end of the slag discharge port of the mechanized tar ammonia water separation tank, including: tar residue liquefaction unit, grinding pump, centrifuge and dry particle conveying device. The tar residue liquefaction unit is a liquefaction tank, which reduces viscosity by adding hot tar. High-efficiency grinding pump: crushes lumpy tar residue to below 3mm; Vertical screw centrifuge: achieves solid-liquid separation, and the separated tar is returned to the tar system; The drying particle conveying device is a slag hopper box, which directly conveys the deoiled tar residue particles (oil content ≤15%) to the coal briquetting workshop for coal blending.

[0013] The PLC control system is a centralized monitoring and intelligent optimization system for the entire process. All sensors, actuators, pumps and valves are connected to the central PLC control system (Siemens S7-400 from Germany) to achieve: real-time monitoring of liquid level and flow rate; fault alarm and interlock protection; and historical data storage and trend analysis.

[0014] This invention, for the first time, constructs a four-in-one technical system integrating "structural optimization, intelligent control, reagent synergy, and slag recycling," breaking through the bottlenecks of traditional processes. It provides a method for the synergistic regulation of low oil content and high-quality tar in circulating ammonia water of coking plants, including the following: (1) Introduce high-precision level gauges and automatic regulating valves into mechanized tar-ammonia water separation tanks and tar separators, and combine PLC control and PID algorithm to achieve precise interlocking control of liquid level and stabilize oil-water interface; (2) The four parallel circulating ammonia tanks were modified into a series structure to enhance the oil phase separation and suspended solids settling effect, and an oil and slag discharge device was added to the bottom of each circulating ammonia tank. (3) A demulsifier and flocculant quantitative addition system is set at the water inlet of the tar ammonia water separation tank to promote the demulsification and aggregation of emulsified tar and the sedimentation of solid suspended matter; The demulsifier is SP-169 or CN71700; the flocculant is polyacrylamide CPAM-80. (4) Implement demulsifier synergistic injection at multiple key points to comprehensively improve tar demulsification efficiency; The aforementioned key locations refer to the inlet position of the circulating ammonia pump, the inlet position of the condensate circulation pump in the upper section of the primary cooler, or the inlet position of the condensate circulation pump in the lower section of the primary cooler. (5) Construct a fully automatic tar residue draining device to liquefy, grind and centrifuge the viscous tar residue to achieve hazardous waste reduction and resource recycling; (6) Full-process automated control and reagent synergistic dosing strategy to improve system operation stability and tar quality consistency.

[0015] Furthermore, the PLC controller embeds a PID algorithm. The PID algorithm is a framework algorithm; its internal parameters—proportional parameter P, integral parameter I, and derivative parameter D—are calibrated based on field control parameters and then rationally adjusted according to the actual field process. In this invention, the PID algorithm is a precise steady-state control method for the oil-water interface based on PID closed-loop control. Operators in the central control room set the interface value of the mechanized tar-ammonia-water separation tank according to process requirements. The control computer sends the signal to the central processing unit (CPU) of the PLC control system. The CPU outputs a coarse adjustment control signal based on the PID algorithm, and the signal is then sent to the control panel. The control panel converts a small current signal into a large current signal, which is then output to the tar-ammonia outlet regulating valve to adjust the liquid level. The hysteresis extensibility interface instrument detects the interface value of tar-ammonia in real time. This interface value signal is transmitted to the central processing unit (CPU) of the PLC control system. The CPU then outputs a fine-tuning signal based on the PID algorithm. The adjustment is repeated cyclically until the actual interface value of tar-ammonia is within ±2mm of the target value. One control cycle is in the millisecond range, so the interface value of tar-ammonia can be adjusted to a reasonable value relatively quickly. Since tar and ammonia have similar densities, conventional level gauges cannot accurately measure the tar-ammonia interface in mechanized tar-ammonia separation tanks and tar separators. Therefore, a magnetic hysteresis-strictive level transmitter (based on the hysteresis effect and electromagnetic induction, with a measurement accuracy of ±0.5mm) is selected to acquire the tar-ammonia interface position signal in real time. This is integrated into a PLC control system, with target level ranges set at 1.15–1.20m (mechanized tar-ammonia separation tank) and 2.00–2.15m (tar separator). A PID control algorithm dynamically outputs adjustment signals to the electric regulating valve, enabling automatic oil discharge and forming a closed-loop control circuit. This keeps level fluctuations within ±0.05m, preventing tar overflow or insufficient oil discharge.

[0016] Furthermore, the horizontal tube primary cooler is connected to the electrostatic precipitator and the blower, and the separated coal gas is sent to the ammonium sulfate process; The tar residue is liquefied with oil in a liquefaction tank, crushed by a grinding pump, separated by a centrifuge, and dried into granules in a slag hopper before being sent to the briquetting workshop.

[0017] The mechanized tar-ammonia water separation tank separates tar, ammonia water and tar residue. Its ammonia water outlet is connected to the first-stage circulating ammonia water tank, its tar outlet is connected to the tar separation tank, and its tar residue outlet is connected to the tar residue draining device. The tar residue is liquefied with oil in the liquefaction tank, crushed by the grinding pump, separated by the centrifuge, and dried into granules in the slag hopper box, which are then sent to the briquetting workshop.

[0018] The reagent quantitative dosing system is a multi-point synergistic demulsifier dosing system. The demulsifier is a hydroxyl-based, water-in-oil, coal tar demulsifier, which can be SP-169 or CN71700. The dosage of the demulsifier at each dosing point is as follows: - Point A: Inlet of the circulating ammonia pump, add demulsifier to pretreat the main circulating flow; dosage is 160~180ppm. - Point B: Inlet of the condensate pump in the lower section of the horizontal tube primary cooler, used to treat the condensate in the high-temperature section; dosage is 60~80ppm. - Point C: Inlet of the condensate pump in the upper section of the horizontal tube primary cooler, used to treat the condensate in the low-temperature section; dosage is 60~80ppm. - Point D: The inlet of the mechanized tar-ammonia-water separation tank to achieve enhanced demulsification; the dosage is 20~40ppm; - Point E: Two primary circulating ammonia tanks are filled to the top to achieve final demulsification; the dosage is 10~30ppm.

[0019] The flocculant addition point is located at the front end of the mechanized tar-ammonia water separation tank, and the flocculant is cationic PAM.

[0020] A flocculant injection unit is installed next to the circulating ammonia water inlet pipe of the mechanized tar-ammonia water separation tank. The flocculant is added simultaneously with the demulsifier to promote the aggregation of fine tar particles and suspended solids into large flocs, accelerate sedimentation, and improve separation efficiency.

[0021] The beneficial effects of this invention are: (1) This invention proposes for the first time an integrated architecture of “precise interface control + series graded settling + multi-point collaborative demulsification + slag resource utilization”, breaking through the traditional single improvement mode and forming a systematic solution; (2) Set up a graded series sedimentation structure for circulating ammonia water tank to improve the oil-water separation efficiency and suspended solids removal capacity of circulating ammonia water in the system. Reduce the oil level of the mechanized tar ammonia water separator and the series tank design to extend the effective residence time by more than 30%. Combined with multi-point demulsification and flocculation, the oil content of circulating ammonia water is reduced from 1200 mg / L to below 300 mg / L. (3) A quantitative dosing system for demulsifier and flocculant is set at the inlet of the tar ammonia water separation tank to enhance the chemical demulsification kinetics of emulsified tar; reduce operating costs and environmental risks: reduce reagent waste by more than 15%, extend equipment maintenance cycle, and avoid VOCs and soil pollution caused by open-air stockpiling of tar residue; (4) Construct a fully automatic tar residue draining device to liquefy, grind and centrifuge the viscous tar residue to achieve fully automatic deoiling and resource recycling of tar residue; realize closed-loop utilization of tar residue resources: the oil content of tar residue is reduced from 40% to below 15%, and thousands of tons of tar can be recovered annually, reducing hazardous waste emissions; (5) This invention significantly reduces the oil content of circulating ammonia water (≤300 mg / L) and improves the quality of tar (moisture content ≤3.0%). The tar moisture content is reduced from 5.5% to below 3.0%, meeting the GB / T 24207-2009 Grade 1 tar standard and increasing its sales value. (6) By setting up a PLC control system, high-precision dynamic and stable control of the oil-water interface of the mechanized tar-ammonia water separation tank and tar separator was realized; a fully automated operation system was constructed to improve system safety and maintainability; high-precision dynamic and stable control of the oil-water interface was realized: the liquid level fluctuation was reduced from ±0.4m to ±0.05m by using a PID closed-loop algorithm, which significantly reduced the risk of tar overflow and water entrainment.

[0022] (7) This invention promotes the intelligent transformation of the coking industry: realizes full-process automated operation, reduces manual intervention, and improves the level of inherent safety; it not only solves common problems in the industry, but also provides a new model of efficient separation and resource recycling of coking by-products that can be replicated and promoted, with significant technological advancement and industrial application prospects. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the co-regulation system for low oil content and high tar in circulating ammonia water of a coking plant according to the present invention.

[0024] Figure 2 This is a schematic diagram of a tar-ammonia-water separation device.

[0025] In the diagram: 1 is a gas-liquid separator, 2 is a mechanized tar-ammonia water separation tank, 3 is a first-stage circulating ammonia water tank, 4 is a second-stage circulating ammonia water tank, 5 is a circulating ammonia water pump, 6 is a lower-stage condensate circulation tank, 7 is a lower-stage circulation pump, 8 is a horizontal tube primary cooler, 9 is an upper-stage condensate circulation tank, 10 is an upper-stage circulation pump, 11 is a liquefaction tank, 12 is a grinding pump, 13 is a centrifuge, 14 is a slag hopper, 15 is a ceramic membrane filter, 16 is a residual ammonia water tank, 17 is a super centrifuge, 18 is a tar storage tank, 19 is an electrostatic precipitator for tar, 20 is a blower, 21 is a tar separation tank, 22 is a hysteresis extensibility interface meter, 23 is an automatic regulating valve, 24 is an oil drain valve, and 25 is an oil removal filter. Detailed Implementation

[0026] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments. Example 1

[0027] like Figures 1-2 As shown, a coking plant circulating ammonia water low oil content and high tar synergistic control system includes a gas-liquid separation device, a tar-ammonia water separation device, a reagent quantitative dosing device, a tar residue draining device, and a PLC control system. The gas-liquid separation device includes a gas-liquid separator 1, a horizontal tube primary cooler 8, an upper condensate circulation tank 9, and a lower condensate circulation tank 6. One end of the gas-liquid separator 1 is connected to the coke oven, and the other end is connected to the horizontal tube primary cooler 8. The condensate separated by the gas-liquid separator 1 enters the tar-ammonia-water separation device. The lower condensate circulation tank 6 is connected to the lower circulation pump 7, forming a circulation loop with the lower section of the horizontal tube primary cooler. The upper condensate circulation tank 9 is connected to the upper circulation pump 10, forming a circulation loop with the upper section of the horizontal tube primary cooler. Excess condensate enters the tar-ammonia-water separation device. The horizontal tube primary cooler 8 is connected to the electrostatic precipitator 19 and the blower 20, which directs the separated coal gas to the ammonium sulfate process. The tar-ammonia water separation device includes a mechanized tar-ammonia water separation tank 2, a first-stage circulating ammonia water tank 3, and a second-stage circulating ammonia water tank 4, forming a staged series sedimentation structure. The second-stage circulating ammonia water tank 4 is connected to a circulating ammonia water pump 5, which pumps the treated ammonia water into the coke oven for recycling. The mechanized tar-ammonia water separation tank 2 separates tar, ammonia water, and tar residue. Its ammonia water outlet is connected to the first-stage circulating ammonia water tank 3, its tar outlet is connected to the tar separation tank 21, and its tar residue outlet is connected to the tar residue draining device. The quantitative dosing device includes a multi-point synergistic demulsifier dosing device and a flocculant dosing device. The demulsifier dosing device is a five-stage demulsifier dosing network covering the source of emulsion formation and the treatment path. Specifically, the dosing points are located at: Point A: the inlet of the circulating ammonia pump, where demulsifier is added to pre-treat the main circulating flow; Point B: the inlet of the condensate pump in the lower section of the horizontal tube primary cooler, where the high-temperature condensate is treated; Point C: the inlet of the condensate pump in the upper section of the horizontal tube primary cooler, where the low-temperature condensate is treated; Point D: the front end of the mechanized tar-ammonia water separator, where enhanced demulsification is achieved; Point E: the top of two first-stage circulating ammonia water tanks (tanks #1 and #2 are connected in series to form a first-secondary system, and tanks #3 and #4 are connected in series to form a first-secondary system) for final demulsification; the flocculant dosing point is located at the front end of the mechanized tar-ammonia water separator. Figure 1 The image shows five dosing points: A, B, C, D, and E.

[0028] The tar residue draining device includes a liquefaction tank 11, a grinding pump 12, a centrifuge 13, and a slag hopper 14 connected in sequence. The liquefaction tank 11 is connected to a mechanized tar-ammonia water separation tank 2, and the tar residue enters the liquefaction tank 11. The tar residue is liquefied with oil in the liquefaction tank 11, crushed by the grinding pump 12, separated by the centrifuge 13, and dried into granules in the slag hopper 14, which are then sent to the briquetting workshop.

[0029] Control system: includes hysteresis extensor interface instrument 22, automatic regulating valve 23, Siemens PLC logic controller, electrical control panel, and operating system terminal computer. The hysteresis extensor interface instrument 22 is installed in the mechanized tar-ammonia water separation tank 2. Its purpose is to display the interface position (liquid level) of tar and ammonia water in real time. The liquid level will be controlled by adjusting the opening of the automatic regulating valve according to the liquid level change, with a control accuracy of ±2mm.

[0030] Furthermore, the tar-ammonia water separation device is a staged series sedimentation structure with circulating ammonia water tanks, such as... Figure 2 As shown, the invention includes four circulating ammonia tanks, corresponding to four mechanized tar-ammonia separation tanks 2. This is one of the innovative aspects of the invention. Specifically, the four mechanized tar-ammonia separation tanks 2 are connected in parallel, and the four circulating ammonia tanks are designated as 1#, 2#, 3#, and 4#. Tanks 1# and 2#, connected in series, are connected in parallel with tanks 3# and 4#, respectively. That is, tanks 1# and 2# are connected in series to form the first-stage circulating ammonia tank 3 and the second-stage circulating ammonia tank 4, while tanks 3# and 4# are connected in series to form... Another set of first-stage and second-stage circulating ammonia tanks, and mechanized tar-ammonia water separation tank 2 are connected in series to the first-stage and second-stage circulating ammonia tanks respectively to achieve staged sedimentation; operation mode: the first-stage circulating ammonia tank serves as the main sedimentation zone, undertaking most of the functions of oil droplet separation and suspended solids sedimentation; the second-stage circulating ammonia tank serves as a buffer and pressure stabilization zone to ensure stable effluent water quality; oil drain valves are installed at the bottom of both the first-stage and second-stage circulating ammonia tanks, which are opened to drain oil and slag according to the thickness of the sediment or a timed program to prevent sediment back-mixing from affecting the separation efficiency.

[0031] Furthermore, the second-stage circulating ammonia tank 4 mainly discharges ammonia water, and an oil drain valve 24 is installed at the bottom (to discharge a small amount of tar that settles to the bottom of the tank). The second-stage circulating ammonia tank 4 is connected to the circulating ammonia pump 5, and an oil removal filter 25 is installed on the outlet pipe of the circulating ammonia pump 5. Most of the filtered ammonia water is sent to the coke oven for circulating spraying, and the excess ammonia water is sent to the ammonium sulfate ammonia stripping system through the ceramic membrane filter 15 and the remaining ammonia water tank 16.

[0032] Furthermore, each drug dispensing point is equipped with a high-precision metering pump and flow meter, and the dosage is adjusted proportionally according to the corresponding fluid flow rate to create a gradient demulsification effect.

[0033] The tar residue draining device is a fully automatic tar residue draining and resource recovery system. The tar residue draining device is constructed at the rear end of the slag discharge port of the mechanized tar ammonia water separation tank 2, and includes: tar residue liquefaction unit, grinding pump, centrifuge and dry particle conveying device. The tar residue liquefaction unit is a liquefaction tank, which reduces viscosity by adding hot tar. High-efficiency grinding pump: crushes lumpy tar residue to below 3mm; Vertical screw centrifuge: achieves solid-liquid separation, and the separated tar is returned to the tar system; The drying particle conveying device is a slag hopper box, which directly conveys the deoiled tar residue particles (oil content ≤15%) to the coal briquetting workshop for coal blending.

[0034] The PLC control system is a centralized monitoring and intelligent optimization system for the entire process. All sensors, actuators, pumps and valves are connected to the central PLC control system (Siemens S7-400 from Germany) to achieve: real-time monitoring of liquid level and flow rate; fault alarm and interlock protection; and historical data storage and trend analysis.

[0035] This invention, for the first time, constructs a four-in-one technical system integrating "structural optimization, intelligent control, reagent synergy, and slag recycling," breaking through the bottlenecks of traditional processes. It provides a method for the synergistic regulation of low oil content and high-quality tar in circulating ammonia water of coking plants, including the following: (1) Introduce high-precision level gauges and automatic regulating valves into mechanized tar-ammonia water separation tanks and tar separators, and combine PLC control and PID algorithm to achieve precise interlocking control of liquid level and stabilize oil-water interface; (2) The four parallel circulating ammonia tanks were modified into a series structure to enhance the oil phase separation and suspended solids settling effect, and an oil and slag discharge device was added to the bottom of each circulating ammonia tank. (3) A demulsifier and flocculant quantitative addition system is set at the water inlet of the tar ammonia water separation tank to promote the demulsification and aggregation of emulsified tar and the sedimentation of solid suspended matter; The demulsifier is SP-169 or CN71700; the flocculant is polyacrylamide CPAM-80. (4) Implement demulsifier synergistic injection at multiple key points to comprehensively improve tar demulsification efficiency; (5) Construct a fully automatic tar residue draining device to liquefy, grind and centrifuge the viscous tar residue to achieve hazardous waste reduction and resource recycling; (6) Full-process automated control and reagent synergistic dosing strategy to improve system operation stability and tar quality consistency.

[0036] Furthermore, the PLC controller has an embedded PID algorithm. The PID algorithm is a framework algorithm, and its internal parameters, proportional parameter P, integral parameter I, and derivative parameter D, are calibrated based on the field control parameters and then rationally adjusted according to the actual field process.

[0037] In this invention, the PID algorithm is a precise steady-state control method for the oil-water interface based on PID closed-loop control. Operators in the central control room set the interface value of the mechanized tar-ammonia water separation tank according to process requirements. The control computer sends the signal to the CPU of the PLC control system. The CPU outputs a coarse adjustment control signal based on the PID algorithm, which is then sent to the control panel. The control panel converts the small current signal into a large current signal, which is then output to the tar-ammonia water outlet regulating valve to adjust the liquid level. A hysteresis-extension interface meter detects the tar-ammonia water interface value in real time. This interface value signal is transmitted to the CPU of the PLC control system, which again outputs a fine adjustment signal based on the PID algorithm. This cycle is repeated until the actual tar-ammonia water interface value is within ±2mm of the target value. One control cycle is in the millisecond range, thus the tar-ammonia water interface value can be adjusted to a reasonable value relatively quickly. Since tar and ammonia have similar densities, conventional level gauges cannot accurately measure the tar-ammonia interface in mechanized tar-ammonia separation tanks and tar separators. Therefore, a magnetic hysteresis-strictive level transmitter (based on the hysteresis effect and electromagnetic induction, with a measurement accuracy of ±0.5mm) is selected to acquire the tar-ammonia interface position signal in real time. This is integrated into a PLC control system, with target level ranges set at 1.15–1.20m (mechanized tar-ammonia separation tank) and 2.00–2.15m (tar separator). A PID control algorithm dynamically outputs adjustment signals to the electric regulating valve, enabling automatic oil discharge and forming a closed-loop control circuit. This keeps level fluctuations within ±0.05m, preventing tar overflow or insufficient oil discharge.

[0038] Furthermore, the horizontal tube primary cooler is connected to the electrostatic precipitator and the blower, and the separated coal gas is sent to the ammonium sulfate process; The tar residue is liquefied with oil in a liquefaction tank, crushed by a grinding pump, separated by a centrifuge, and dried into granules in a slag hopper before being sent to the briquetting workshop.

[0039] The mechanized tar-ammonia water separation tank separates tar, ammonia water and tar residue. Its ammonia water outlet is connected to the first-stage circulating ammonia water tank, its tar outlet is connected to the tar separation tank, and its tar residue outlet is connected to the tar residue draining device. The tar residue is liquefied with oil in the liquefaction tank, crushed by the grinding pump, separated by the centrifuge, and dried into granules in the slag hopper box, which are then sent to the briquetting workshop.

[0040] The drug quantitative dosing system is a multi-point synergistic demulsifier dosing system. The demulsifier is a hydroxyl, water-in-oil, coal tar demulsifier, which can be SP-169 or CN71700.

[0041] The flocculant addition point is located at the front end of the mechanized tar-ammonia water separation tank, and the flocculant is cationic PAM.

[0042] A flocculant injection unit is installed next to the circulating ammonia water inlet pipe of the mechanized tar-ammonia water separation tank. The flocculant is added simultaneously with the demulsifier to promote the aggregation of fine tar particles and suspended solids into large flocs, accelerate sedimentation, and improve separation efficiency.

[0043] The specific modification process in this embodiment is as follows: 1. Equipment modification: - The original four parallel circulating ammonia tanks (Φ7m×4.2m) were changed to be connected in series in pairs and then in parallel. - Add a DN80 oil drain valve to the bottom of the first and second stage circulating ammonia tanks in each group; - Mechanized tar-ammonia-water separation tank and tar separator with hysteresis telescopic interface analyzer and electric regulating valve (Fisher Easy-Flow). - Construct a new demulsifier dosing station, equipped with five metering pumps (corresponding to points A, B, C, and E respectively), and a mechanized tar-ammonia-water separation tank front-end dosing system (point D). - A new tar residue processing workshop will be built, equipped with liquefaction tanks, crushers, vertical centrifuges (processing capacity 10t / h), slag hoppers, and control systems.

[0044] 2. Control system: - All instruments are connected to the Siemens S7-400 PLC control system, and the configuration screen is displayed in the central control room; - Liquid level control settings: 1.15-1.2m for mechanized tar-ammonia water separation tank, 2.0-2.15m for tar separator; - PID parameter tuning: proportional gain Kp = 0.65, integral time Ti = 8s; - The slag discharge cycle is set to continuous slag discharge, with automatic interlocking start and stop based on the liquid level in the liquefied tank. When the liquid level reaches 750mm, the transfer pump, grinding pump, centrifuge, and other equipment will automatically start to drain the tar residue, and will stop when the liquid level drops by 100mm.

[0045] 3. Selection and dosage of reagents: - Demulsifier: The dosage of demulsifier at each injection point is as follows: - Point A: CN71700, inlet of circulating ammonia pump, add demulsifier to pretreat the main circulation flow; dosage is 170ppm. - Point B: CN71700, inlet of the condensate pump in the lower section of the horizontal tube primary cooler, for treating condensate in the high-temperature section; dosage is 70ppm. - Point C: CN71700, inlet of the condensate pump in the upper section of the horizontal tube primary cooler, for treating the low-temperature condensate; dosage is 70ppm. - Point D: CN71700, the front end of the mechanized tar-ammonia-water separator inlet, to achieve enhanced demulsification; dosage is 30ppm; - Point E: CN71700, two primary circulating ammonia tanks are installed at the top to achieve final demulsification, with a dosage of 20ppm.

[0046] - Flocculant: Cationic polyacrylamide CPAM-80, dosage concentration: 10 ppm.

[0047] 4. Operational Results (Statistics after 6 Months of Continuous Operation): - Average oil content in circulating ammonia water: 280 mg / L (originally 500-1200 mg / L); - Average moisture content of tar: 2.8% (originally 5.2%); - Oil content of tar residue: 14.5%; - Recovers approximately 3,000 tons of tar annually, saving 15% on reagent costs; - No tar spillage occurred, and the system is operating stably.

[0048] After the implementation of the method of this invention, the oil content of the circulating ammonia water is stably controlled at ≤300 mg / L, the moisture content of the tar is reduced to ≤3.0%, the oil content of the tar residue is reduced from 30%–40% to ≤15%, more than 3,000 tons of tar can be recovered annually, the system operation stability is significantly improved, and it has significant economic, environmental and promotional value.

Claims

1. A synergistic control system for low oil content and high tar content in circulating ammonia water of a coking plant, characterized in that, It includes a gas-liquid separation device, a tar-ammonia-water separation device, a reagent quantitative dosing device, a tar residue draining device, and a control system; The gas-liquid separation device includes a gas-liquid separator, a horizontal tube primary cooler, an upper condensate circulation tank, and a lower condensate circulation tank. One end of the gas-liquid separator is connected to the coke oven, and the other end is connected to the horizontal tube primary cooler. The condensate separated by the gas-liquid separator enters the tar-ammonia-water separation device. The lower condensate circulation tank is connected to the lower circulation pump, forming a circulation loop with the lower section of the horizontal tube primary cooler. The upper condensate circulation tank is connected to the upper circulation pump, forming a circulation loop with the upper section of the horizontal tube primary cooler. Excess condensate enters the tar-ammonia-water separation device. The tar-ammonia water separation device includes a mechanized tar-ammonia water separation tank, a first-stage circulating ammonia water tank, and a second-stage circulating ammonia water tank, forming a staged series sedimentation structure. The second-stage circulating ammonia water tank is connected to a circulating ammonia water pump, which pumps the treated ammonia water into the coke oven for recycling. The mechanized tar-ammonia water separation tank separates tar, ammonia water, and tar residue. Its ammonia water outlet is connected to the first-stage circulating ammonia water tank, its tar outlet is connected to the tar separation tank, and its tar residue outlet is connected to a tar residue draining device. The quantitative dosing device for the agent includes a multi-point synergistic demulsifier dosing device and a flocculant dosing device. The demulsifier dosing device is a five-level demulsifier dosing network covering the source of emulsion formation and the treatment path. The tar residue draining device includes a liquefaction tank, a grinding pump, a centrifuge, and a slag hopper connected in sequence. The liquefaction tank is connected to a mechanized tar-ammonia water separation tank, and the tar residue enters the liquefaction tank. The tar residue is liquefied with oil in the liquefaction tank, crushed by the grinding pump, separated by the centrifuge, and dried into granules in the slag hopper, which are then sent to the briquetting workshop. Control system: includes a hysteresis extensor interface instrument, an automatic regulating valve, a PLC controller, an electrical control panel, and an operating system terminal computer. The hysteresis extensor interface instrument is installed in the mechanized tar-ammonia water separation tank. Its purpose is to display the interface position of tar and ammonia water in real time. The liquid level is controlled by adjusting the opening of the automatic regulating valve according to the liquid level change, with a control accuracy of ±2mm.

2. The coking plant circulating ammonia water low oil content and high tar synergistic control system according to claim 1, characterized in that, The tar-ammonia water separation device is a staged series sedimentation structure with circulating ammonia water tanks, including four circulating ammonia water tanks, which are correspondingly set with four mechanized tar-ammonia water separation tanks. The four mechanized tar-ammonia water separation tanks are set in parallel. The four circulating ammonia water tanks are designated as 1#, 2#, 3#, and 4#. Circulating ammonia water tanks 1# and 2# are connected in series to form the first and second stage circulating ammonia water tanks, respectively. Circulating ammonia water tanks 3# and 4# are connected in series to form another set of first and second stage circulating ammonia water tanks. The mechanized tar-ammonia water separation tanks are connected to the first and second stage circulating ammonia water tanks connected in series, respectively, to achieve staged sedimentation. Operating mode: The first stage circulating ammonia water tank serves as the main sedimentation zone, undertaking most of the oil droplet separation and suspended solids sedimentation functions; the second stage circulating ammonia water tank serves as a buffer and pressure stabilization zone, ensuring stable effluent water quality; oil drain valves are installed at the bottom of both the first and second stage circulating ammonia water tanks, which are opened according to the sediment thickness or a timed program to discharge oil and slag, preventing sediment back-mixing and affecting separation efficiency.

3. The coking plant circulating ammonia water low oil content and high tar synergistic control system according to claim 2, characterized in that, The demulsifier injection points are located at: Point A: inlet of the circulating ammonia pump, where demulsifier is added to pre-treat the main circulating flow; Point B: inlet of the condensate pump in the lower section of the horizontal tube primary cooler, where high-temperature condensate is treated; Point C: inlet of the condensate pump in the upper section of the horizontal tube primary cooler, where low-temperature condensate is treated; Point D: front end of the mechanized tar-ammonia water separator inlet, to achieve enhanced demulsification; Point E: top of the two first-stage circulating ammonia water tanks, to achieve final demulsification. The flocculant injection point is located at the front end of the mechanized tar-ammonia water separator. Each injection point is equipped with a high-precision metering pump and flow meter, and the dosage is adjusted proportionally according to the corresponding fluid flow rate to form a gradient demulsification effect.

4. The coking plant circulating ammonia water low oil content and high tar synergistic control system according to claim 2, characterized in that, The second-stage circulating ammonia tank discharges ammonia water, and an oil drain valve is installed at the bottom. The second-stage circulating ammonia tank is connected to the circulating ammonia pump, and an oil removal filter is installed on the outlet pipe of the circulating ammonia pump. Most of the filtered ammonia water is sent to the coke oven for circulating spraying, and the excess ammonia water is sent to the ammonium sulfate stripping system through the surplus ammonia water tank.

5. The coking plant circulating ammonia water low oil content and high tar synergistic control system according to claim 1, characterized in that, The horizontal tube primary cooler is connected to the electrostatic precipitator and the blower, and the separated coal gas is sent to the ammonium sulfate process.

6. The coking plant circulating ammonia water low oil content and high tar synergistic control system according to claim 1, characterized in that, The control system is a full-process PLC centralized monitoring and intelligent optimization system. All sensors, actuators, pumps and valves are connected to the central PLC control system to achieve: real-time monitoring of liquid level and flow rate; fault alarm and interlock protection; and historical data storage and trend analysis.

7. A method for synergistically controlling low oil content and high tar content in circulating ammonia water of a coking plant, comprising the synergistic control system for low oil content and high tar content in circulating ammonia water of a coking plant as described in any one of claims 1 to 6, characterized in that, Includes the following: (1) Introduce high-precision level gauges and automatic regulating valves into mechanized tar-ammonia water separation tanks and tar separators, and combine PLC control and PID algorithm to achieve precise interlocking control of liquid level and stabilize oil-water interface; (2) The four parallel circulating ammonia tanks were modified into a series structure to enhance the oil phase separation and suspended solids settling effect, and an oil and slag discharge device was added to the bottom of each circulating ammonia tank. (3) A demulsifier and flocculant quantitative addition system is set at the water inlet of the tar ammonia water separation tank to promote the demulsification and aggregation of emulsified tar and the sedimentation of solid suspended matter; (4) Implement demulsifier co-application at multiple key points to comprehensively improve tar demulsification efficiency; key points refer to the inlet position of the circulating ammonia pump, the inlet position of the condensate circulating pump in the upper section of the primary cooler, or the inlet position of the condensate circulating pump in the lower section of the primary cooler. (5) Construct a fully automatic tar residue draining device to liquefy, grind and centrifuge the viscous tar residue to achieve hazardous waste reduction and resource recycling; (6) Full-process automated control and reagent synergistic dosing strategy to improve system operation stability and tar quality consistency.

8. The method for synergistic regulation of low oil content and high tar content in circulating ammonia water of a coking plant according to claim 7, characterized in that, The demulsifier is SP-169 or CN71700; the flocculant is polyacrylamide CPAM-80.

9. The method for synergistic regulation of low oil content and high tar in circulating ammonia water of a coking plant according to claim 8, characterized in that, The demulsifier is a hydroxyl-based, water-in-oil, coal tar demulsifier, selected from SP-169 or CN71700; the dosage of the demulsifier at each injection point is as follows: Point A: Inlet of the circulating ammonia water pump, dosage is 160~180ppm; Point B: Inlet of the condensate pump in the lower section of the horizontal tube primary cooler, dosage is 60~80ppm; Point C: Inlet of the condensate pump in the upper section of the horizontal tube primary cooler, dosage is 60~80ppm; Point D: Front end of the water inlet of the mechanized tar ammonia water separator, dosage is 20~40ppm; Point E: Top of the two first-stage circulating ammonia water tanks, dosage is 10~30ppm. The flocculant addition point is located at the front end of the mechanized tar-ammonia water separation tank, and the flocculant is cationic PAM. A flocculant injection unit is set up next to the circulating ammonia water inlet pipe of the mechanized tar-ammonia water separation tank, and is added synchronously with the demulsifier to promote the aggregation of fine tar particles and suspended matter into large flocs, accelerate sedimentation, and improve separation efficiency.

10. The method for synergistic regulation of low oil content and high tar in circulating ammonia water of a coking plant according to claim 7, characterized in that, The mechanized tar-ammonia water separation tank separates tar, ammonia water and tar residue. Its ammonia water outlet is connected to the first-stage circulating ammonia water tank, its tar outlet is connected to the tar separation tank, and its tar residue outlet is connected to the tar residue draining device. The tar residue is liquefied with oil in the liquefaction tank, crushed by the grinding pump, separated by the centrifuge, and dried into granules in the slag hopper box, which are then sent to the briquetting workshop.

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