Coal-to-methanol ash water treatment system and optimization method

Abstract

The invention discloses a coal-to-methanol ash water treatment system and an optimization method. The coal-to-methanol ash water treatment system comprises a first water heater, a second water heater, a first flash evaporator, a third water heater and a vacuum flash evaporation device; an inlet of the first water heater is connected with a chilling chamber of the gasification furnace; an inlet of the second water heater is connected with a washing tower of a gasification section; an inlet of the first flash evaporator is connected with an air outlet of the first water heater and an air outlet of the second water heater; an inlet of the third water heater is connected with a liquid outlet of the first water heater and a liquid outlet of the second water heater; and the vacuum flash evaporation device is used for further treating liquid at the bottom of the third water heater. According to the method, the salt in the high-concentration brine can be recycled and converted into a product for resource recycling, so that the problem of hazardous waste treatment of crystalline solids in related technologies is solved, the treatment efficiency is improved, and the treatment cost is reduced.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a coal-to-methanol ash water treatment system and its optimization method. Background Technology

[0002] The methanol production process generates a large amount of wastewater. This wastewater contains high levels of ammonia nitrogen compounds and fly ash, which are harmful to both humans and equipment, making it unsuitable for direct reuse and prohibiting arbitrary discharge. It must be collected centrally and sent to a wastewater treatment plant for treatment to meet standards before it can be discharged or reused. The wastewater from coal-to-methanol production has a complex composition and high pollutant content; it is a type of industrial wastewater characterized by high organic matter content, high salinity, and high hardness.

[0003] High-salinity wastewater generally refers to wastewater with a total salt content of not less than 1% by mass. Related technologies mainly involve a series of processes combining pretreatment, concentration, and crystallization techniques. Through concentration, evaporation, and crystallization, water resources are reused and solid salt products are obtained. However, transferring pollution from water to crystalline mixed salts results in complex and unusable mixed crystalline salts. As byproducts of wastewater treatment, they can only be stockpiled, landfilled, or treated as hazardous waste, wasting valuable substances and failing to achieve resource utilization. Crystalline solids are crystalline mixed salts composed of sodium chloride, sodium sulfate, sodium nitrate, heavy metals, and some organic matter. They are highly soluble in water, posing a high risk of secondary pollution through leaching. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a coal-to-methanol ash water treatment system that can achieve differentiated crystallization of high-salt wastewater and improve resource recycling and reuse.

[0006] An optimization method is proposed in the embodiments of the present invention.

[0007] The coal-to-methanol ash water treatment system of this invention includes:

[0008] The first water heater has its inlet connected to the quench chamber of the gasifier so that the ash water discharged from the quench chamber is fed into the first water heater.

[0009] The second water heater has its inlet connected to the scrubbing tower of the gasification section so that the grey water discharged from the scrubbing tower is fed into the second water heater.

[0010] The first flash evaporator has its inlet connected to the gas outlet of the first water heater and the gas outlet of the second water heater, so that the steam in the first water heater and the second water heater is fed into the first flash evaporator for flash separation.

[0011] The third water heater has its inlet connected to the outlets of the first and second water heaters, so that the bottom liquid in the first and second water heaters is transported into the third water heater.

[0012] A vacuum flash evaporation device includes a vacuum flash evaporator, a vacuum flash separator, a vacuum pump, and a vacuum pump separator. The inlet of the vacuum flash evaporator is connected to the third water heater to deliver the bottom liquid of the third water heater into the vacuum flash evaporator. The outlet of the vacuum flash evaporator is connected to the inlet of the vacuum flash separator. The outlet of the vacuum flash separator is connected to the vacuum pump. Part of the condensate discharged by the vacuum pump mixes with the steam discharged from the outlet of the vacuum flash separator and is then delivered into the vacuum pump separator. Another part of the condensate discharged by the vacuum pump is delivered to a deoxygenated water tank. The outlet of the vacuum pump separator is connected to the inlet of the vacuum flash separator so that the bottom liquid of the vacuum pump separator flows back into the vacuum flash separator.

[0013] The coal-to-methanol ash water treatment system of this invention can recover salt from high-concentration brine and convert it into products for resource recycling and reuse. This solves the problem of treating crystalline solids as hazardous waste in related technologies, improves treatment efficiency, and reduces treatment costs.

[0014] In some embodiments, the inlet end of the first flash evaporator is connected to a first mixer and a heater. The steam discharged from the outlet of the first water heater and the outlet of the second water heater enters the heater after passing through the first mixer, so as to exchange heat with the feed water of the washing tower before entering the first flash evaporator.

[0015] In some embodiments, a second mixer and a condenser are provided between the outlet of the vacuum flash evaporator and the inlet of the vacuum flash separator. The steam discharged from the outlet of the vacuum flash evaporator is condensed by the second mixer and the condenser in sequence before entering the vacuum flash separator.

[0016] In some embodiments, the outlet of the vacuum flash separator is connected to a compressor and a third mixer, and the vacuum pump is connected to the third mixer. The steam discharged from the outlet of the vacuum flash separator is mixed with part of the condensate discharged from the vacuum pump in the third mixer after passing through the compressor and then transported into the vacuum pump separator.

[0017] In some embodiments, the outlet end of the vacuum pump is connected to a distributor, which is used to deliver the condensate discharged by the vacuum pump to the deoxygenation water tank and the vacuum pump separator respectively according to a preset ratio, and a drive pump is provided between the distributor and the vacuum pump separator.

[0018] In some embodiments, the inlet of the vacuum flash evaporator is connected to the slag pool to transport the slag water in the slag pool into the vacuum flash evaporator;

[0019] And / or, a cooler is provided between the liquid outlet of the vacuum pump separator and the liquid inlet of the vacuum flash separator.

[0020] The optimization method of this invention is used to optimize the coal-to-methanol ash water treatment system described in any of the above embodiments, the optimization method comprising:

[0021] A mathematical model was constructed using Aspen Plus software based on the aforementioned coal-to-methanol ash water treatment system.

[0022] Given the runtime information, run the mathematical model and obtain a simulation results report;

[0023] The actual operating conditions are retrieved and compared with the simulation results report. The previous step is repeated to obtain the final operating information of the mathematical model.

[0024] Adjust at least some of the operating parameters of the mathematical model to obtain the target result report;

[0025] Determine whether the target result meets the requirements;

[0026] If so, the actual operating parameters of the coal-to-methanol ash water treatment system shall be adjusted based on the target result report.

[0027] In some embodiments, the step of constructing a mathematical model using Aspen Plus software includes:

[0028] Based on the composition of substances flowing into the first and second water heaters, the RKSOAVE property method used by the Aspen Plus software is determined.

[0029] Based on the physical properties and process requirements of each device in the coal-to-methanol ash water treatment system, select the corresponding unit operation module in the AspenPlus software.

[0030] Based on the characteristics of heat flow, material flow and power flow in the coal-to-methanol ash water treatment system, the corresponding thermodynamic model and property database are selected in the Aspen Plus software.

[0031] In some embodiments, in the final operating information, the unit operation module used by the first water heater, second water heater, third water heater, first flash evaporator, vacuum flash evaporator, vacuum flash separator and vacuum pump separator in the coal-to-methanol ash water treatment system is Flash2, and the unit operation module used by the diverter in the coal-to-methanol ash water treatment system is FSplit.

[0032] In the mathematical model constructed using Aspen Plus software, the operating temperature of the first water heater is 180.04 degrees Celsius and the operating pressure is 1 MPa; the operating temperature of the second water heater is 180.1 degrees Celsius and the operating pressure is 1 MPa; the operating temperature of the third water heater is 126.08 degrees Celsius and the operating pressure is 0.23 MPa; the operating temperature of the first flash evaporator is 170.1 degrees Celsius and the operating pressure is 0.86 MPa; the operating temperature of the vacuum flash evaporator is 64.27 degrees Celsius and the operating pressure is 0.02 MPa; the operating temperature of the vacuum flash separator is 39.3 degrees Celsius and the operating pressure is 0.2 MPa; the operating temperature of the vacuum pump separator is 39.3 degrees Celsius and the operating pressure is 0.2 MPa; and the flow splitting ratio from the distributor to the vacuum pump separator is 0.67.

[0033] In some embodiments, the unit operation modules used for the heater, condenser, and cooler in the coal-to-methanol ash water treatment system are all Heater; the unit operation modules used for the vacuum pump and drive pump in the coal-to-methanol ash water treatment system are all Pump; the unit operation modules used for the compressor in the coal-to-methanol ash water treatment system are all Compr; and the unit operation modules used for the first mixer, second mixer, and third mixer in the coal-to-methanol ash water treatment system are all Mixer.

[0034] In the mathematical model constructed using Aspen Plus software, the heater operates at a temperature of 171.29 degrees Celsius and an operating pressure of 0.86 MPa; the condenser operates at a temperature of 39.29 degrees Celsius and an operating pressure of 0.018 MPa; the cooler operates at a temperature of 39.3 degrees Celsius and an operating pressure of 0.018 MPa; the vacuum pump and drive pump both have an outlet pressure of 0.1 MPa; the compressor is of type Isentropic; the compressor's outlet pressure is 0.1 MPa; and the pressure drops of the first mixer, the second mixer, and the third mixer are all 0. Attached Figure Description

[0035] Figure 1 This is a flowchart of the coal-to-methanol ash water treatment system according to an embodiment of the present invention.

[0036] Figure 2This is a flowchart of the optimization method according to an embodiment of the present invention.

[0037] Figure label:

[0038] 11. First water heater; 12. Second water heater; 13. Third water heater; 14. First flash evaporator;

[0039] 21. Vacuum flash evaporator; 22. Vacuum flash separator; 23. Vacuum pump; 24. Vacuum pump separator; 25. Drive pump;

[0040] 31. First mixer; 32. Heater;

[0041] 41. Second mixer; 42. Condenser;

[0042] 51. Compressor; 52. Third mixer;

[0043] 61. Diverter;

[0044] 71. Cooler. Detailed Implementation

[0045] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0046] See Figure 1 The coal-to-methanol ash water treatment system of this invention includes a first water heater 11, a second water heater 12, a first flash evaporator 14, a third water heater 13, and a vacuum flash evaporation device.

[0047] The inlet of the first water heater 11 is connected to the quench chamber of the gasifier so that the ash water discharged from the quench chamber is fed into the first water heater 11. The inlet of the second water heater 12 is connected to the scrubbing tower of the gasification section so that the ash water discharged from the scrubbing tower is fed into the second water heater 12. The inlet of the first flash evaporator 14 is connected to the gas outlet of the first water heater 11 and the gas outlet of the second water heater 12 so that the steam from the first water heater 11 and the second water heater 12 is fed into the first flash evaporator 14 for flash separation.

[0048] In this embodiment, the grey water discharged from the quench chamber and the grey water discharged from the scrubbing tower are flash-evaporated by the first water heater 11 and the second water heater 12, respectively, and flash gases are obtained. After being cooled and mixed, the flash gas enters the first flash evaporator 14 for flash separation again, thereby realizing the first stage of grey water treatment.

[0049] In this embodiment, the first water heater 11, the second water heater 12, and the first flash evaporator 14 all operate in a high-temperature environment, with operating temperatures above 150 degrees Celsius. The operating temperatures of the first water heater 11 and the second water heater 12 reach between 175 and 185 degrees Celsius. The operating temperature of the first flash evaporator 14 is between 165 and 175 degrees Celsius.

[0050] For example, the operating temperature of the first water heater 11 is 180.04 degrees Celsius, and the operating temperature of the second water heater 12 is 180.1 degrees Celsius.

[0051] During operation, the ash water discharged from the quench chamber flows into the first water heater 11 after pressure reduction, and the ash water discharged from the washing tower flows into the second water heater 12 after pressure reduction. The pressure in the first water heater 11 and the second water heater 12 is controlled at approximately 0.9 to 1.1 MPa, for example, the pressure in the first water heater 11 and the second water heater 12 is 1 MPa. The pressure in the first flash evaporator 14 is controlled at approximately 0.8 to 0.9 MPa, for example, the pressure in the first flash evaporator 14 is controlled at 0.86 MPa.

[0052] In this embodiment, the inlet of the third water heater 13 is connected to the outlet of the first water heater 11 and the outlet of the second water heater 12, so that the bottom liquid in the first water heater 11 and the second water heater 12 is transported into the third water heater 13.

[0053] The third water heater 13 is a low-temperature water heater with an operating temperature between 110 degrees Celsius and 130 degrees Celsius. For example, the operating temperature of the third water heater 13 is 126.08 degrees Celsius. The operating pressure of the third water heater 13 is controlled between 0.2MPa and 0.25MPa. For example, the operating pressure of the third water heater 13 is 0.23MPa.

[0054] The third water heater 13 uses a relatively low temperature environment to process the liquid discharged from the first water heater 11 and the second water heater 12. During this process, the liquid level at the bottom of the first and second water heaters 11 can be adjusted to allow liquid to enter the third water heater 13. The liquid and fine sludge at the bottom of the third water heater 13 can then enter the subsequent vacuum flash evaporation device based on the liquid level adjustment, thereby ensuring the stability of the system.

[0055] The first water heater 11, the second water heater 12, and the third water heater 13 in this embodiment of the invention can all be equipped with a flash evaporation device.

[0056] The vacuum flash evaporation device in this embodiment can not only treat the liquid and fine slag discharged from the third water heater 13, but also treat the fine slag water in the slag pool in the plant area.

[0057] The vacuum flash evaporation device includes a vacuum flash evaporator 21, a vacuum flash separator 22, a vacuum pump 23, and a vacuum pump separator 24. The inlet of the vacuum flash evaporator 21 is connected to the third water heater 13 to transport the liquid at the bottom of the third water heater 13 into the vacuum flash evaporator 21. The inlet of the vacuum flash evaporator 21 is also connected to the sludge tank to transport the sludge water in the sludge tank into the vacuum flash evaporator 21 for treatment.

[0058] The outlet of vacuum flash evaporator 21 is connected to the inlet of vacuum flash separator 22. The flash vapor discharged from vacuum flash evaporator 21 is condensed and enters vacuum flash separator 22, while the liquid at the bottom of vacuum flash evaporator 21 is discharged. The outlet of vacuum flash separator 22 is connected to vacuum pump 23, which pumps the liquid at the bottom of vacuum flash separator 22 and mixes part of the condensate pumped by vacuum pump 23 with the vapor discharged from the outlet of vacuum flash separator 22 before conveying it into vacuum pump separator 24 for further separation. Another portion of the condensate discharged by vacuum pump 23 is conveyed to deoxygenation water tank.

[0059] The non-condensable gas at the outlet of the vacuum pump separator 24 can be discharged into the atmosphere. The liquid outlet of the vacuum pump separator 24 is connected to the inlet of the vacuum flash separator 22 so that the liquid at the bottom of the vacuum pump separator 24 flows back into the vacuum flash separator 22. Thus, the liquid separated by the vacuum pump separator 24 is condensed and returned to the vacuum flash separator 22 to achieve circulation.

[0060] In this embodiment, a distributor 61 is connected to the outlet end of the vacuum pump 23. The distributor 61 is used to deliver the condensate discharged by the vacuum pump 23 to the deoxygenation water tank and the vacuum pump separator 24 respectively according to a preset ratio. For example, the flow rate to the vacuum pump separator 24 accounts for 0.67 of the total flow rate. A drive pump 25 is provided between the distributor 61 and the vacuum pump separator 24. The drive pump 25 can adjust the liquid pressure flowing to the vacuum pump separator 24.

[0061] The operating temperature of the vacuum flash evaporator 21 can be from 55 degrees Celsius to 70 degrees Celsius; for example, the operating temperature inside the vacuum flash evaporator 21 is 64.27 degrees Celsius. The operating temperature of the vacuum flash separator 22 can be from 35 degrees Celsius to 45 degrees Celsius; for example, the operating temperature inside the vacuum flash separator 22 is 39.3 degrees Celsius. The operating temperature of the vacuum pump separator 24 can be from 35 degrees Celsius to 45 degrees Celsius; for example, the operating temperature of the vacuum pump separator 24 is 39.3 degrees Celsius.

[0062] In this embodiment, the vacuum flash evaporator 21 and vacuum flash separator 22 operate in a vacuum environment, with the operating pressure controlled below 0.05 MPa. For example, the operating pressure of the vacuum flash evaporator 21 and vacuum flash separator 22 is 0.02 MPa. The operating pressure of the vacuum pump separator 24 can be from 0.1 to 0.3 MPa, for example, the operating pressure of the vacuum pump separator 24 is 0.2 MPa.

[0063] The coal-to-methanol ash water treatment system of this invention, through multi-stage separation and treatment, can recover salt from high-concentration brine and convert it into products for resource recycling and reuse. This solves the problem of treating crystalline solids as hazardous waste in related technologies, improves treatment efficiency, reduces treatment costs, and enables the recycling of ash water, achieving zero wastewater discharge. It also avoids secondary pollution caused by treated waste.

[0064] In some embodiments, the inlet end of the first flash evaporator 14 is connected to a first mixer 31 and a heater 32. Steam discharged from the outlets of the first water heater 11 and the second water heater 12 enters the heater 32 after passing through the first mixer 31, where it exchanges heat with the feed water of the scrubbing tower before entering the first flash evaporator 14. In this embodiment, the first mixer 31 can be used to mix the flash steam from the first heater 32 and the flash steam from the second heater 32. Heat exchange can occur within the heater 32 with the feed water flowing into the scrubbing tower. After being cooled by the heat exchange, the flash steam flows into the first flash evaporator 14, thereby ensuring the stability of the fluid properties entering the first flash evaporator 14 and guaranteeing the normal and stable operation of the first heater 32.

[0065] In some embodiments, a second mixer 41 and a condenser 42 are provided between the outlet of the vacuum flash evaporator 21 and the inlet of the vacuum flash separator 22. The steam discharged from the outlet of the vacuum flash evaporator 21 is condensed sequentially by the second mixer 41 and the condenser 42 before entering the vacuum flash separator 22. In this embodiment, the flash steam discharged from the vacuum flash evaporator 21 can be mixed with other materials by the second mixer 41, and then condensed by the condenser 42 before entering the vacuum flash separator 22 for gas-liquid separation. This adjusts the characteristics of the fluid entering the vacuum flash separator 22, ensuring the normal and stable operation of the vacuum flash separator 22.

[0066] In some embodiments, the outlet of the vacuum flash separator 22 is connected to a compressor 51 and a third mixer 52. A vacuum pump 23 is connected to the third mixer 52. The vapor discharged from the outlet of the vacuum flash separator 22 is mixed with a portion of the condensate discharged from the vacuum pump 23 in the third mixer 52 after passing through the compressor 51, and then transported into the vacuum pump separator 24. The compressor 51 can compress the vapor discharged from the vacuum flash separator 22, and mix it with a portion of the condensate discharged from the vacuum pump 23 driven by the drive pump 25 in the third mixer 52 before transporting it into the vacuum pump separator 24. This regulates the fluid characteristics entering the vacuum pump separator 24, ensuring the normal and stable operation of the vacuum flash separator 22, thereby achieving gas-liquid separation.

[0067] A cooler 71 is provided between the liquid outlet of the vacuum pump separator 24 and the liquid inlet of the vacuum flash separator 22. The liquid at the bottom of the vacuum pump separator 24 is cooled and then flows back into the vacuum flash separator 22.

[0068] In this embodiment, the vacuum flash evaporator 21, vacuum flash separator 22, and vacuum pump separator 24 perform gas-liquid separation based on their own characteristics throughout the process to ensure the treatment effect of ash water and separate solid components such as ash residue and non-condensable gas.

[0069] This embodiment can treat greywater in multiple stages, so that corresponding recyclable resources and waste can be obtained at different stages, realizing fractional crystallization and resource recycling.

[0070] See Figure 2 The optimization method of this invention is used to optimize the coal-to-methanol ash water treatment system of any of the above-mentioned embodiments. The optimization method includes:

[0071] S101. Based on the coal-to-methanol ash water treatment system, a mathematical model was constructed using Aspen Plus software.

[0072] Based on the design process flow diagram, select unit operation modules to represent the equipment or devices in the actual plant. Connect the selected operation modules with heat flow, material flow and power flow, and finally determine and check the integrity of the process.

[0073] S102. Given the running information, run the mathematical model and obtain the simulation result report.

[0074] The operational information for a given process flow includes the type of simulation operation, the limits of temperature and pressure throughout the process, the basic units of measurement, and the final report format.

[0075] The components, given per-unit streams, and parameters of the established unit modules are generally categorized as: conventional inert solids, conventional components, and unconventional solids. To improve the basic conditions for process simulation, specified information for each per-unit stream must be provided before simulation, such as stream composition, operating pressure, and temperature. The operating parameters of each unit module include its own temperature, pressure, connected stream phase, and heat exchange.

[0076] In steps S101 and S102, different physical property methods will produce different simulation results. Therefore, a suitable physical property method can obtain accurate simulation results.

[0077] The steps involve constructing a mathematical model using Aspen Plus software, including determining the RKSOAVE property method employed by Aspen Plus software based on the composition of substances flowing into the first water heater 11 and the second water heater 12. In the greywater treatment system of this embodiment, the main substances are CO, H2, CO2, N2, and H2O, which are mostly nonpolar or weakly polar systems. Therefore, the RKSOAVE property method is selected for simulation.

[0078] Based on the physical properties and process requirements of each device in the coal-to-methanol ash water treatment system, select the corresponding unit operation module in the Aspen Plus software.

[0079] Based on the characteristics of heat flow, material flow, and power flow in the coal-to-methanol ash water treatment system, the corresponding thermodynamic model and property database are selected in the Aspen Plus software.

[0080] Aspen Plus software offers a variety of unit operation modules (such as Heater, Mixer, RadFrac, etc.) for simulating different process equipment. For example: Heater: used to simulate heater 32 or cooler 71; Mixer: used to simulate a mixer; RadFrac: used to simulate a distillation column. The selection of these modules is based on the physical functions and process requirements of the actual equipment.

[0081] When using the same model, different equipment will require different parameter settings. For example, for a Heater, inlet and outlet temperatures, pressures, and heat loads need to be set. For RadFrac, the number of trays, reflux ratio, and feed location need to be set. The parameter settings are based on the actual process conditions and equipment design data.

[0082] Grey water treatment systems involve complex multiphase flows and chemical reactions, requiring careful selection of modules and parameter settings. For example, when using the Flash module to simulate a flash evaporation process, the flash pressure and temperature must be accurately set.

[0083] Based on the characteristics of heat flow, material flow, and power flow, appropriate module combinations should be selected to optimize energy utilization and material separation. Ash water treatment units involve high-solids-content or high-viscosity materials, requiring the selection of suitable modules and the setting of reasonable parameters.

[0084] Based on actual process conditions, select appropriate property analysis methods and thermodynamic models to ensure the accuracy of calculation results. Ash water treatment units involve complex property calculations (such as high-solids-content streams), requiring the selection of suitable property analysis methods and models. For example, use NRTL or UNIQUAC models to calculate liquid phase activity coefficients, or use SRK or PR equations to calculate gas phase fugacity. In ash water treatment using Aspen Plus, the selection of equipment models and parameter settings are crucial.

[0085] This embodiment can accurately simulate heat flow, material flow, and work flow by reasonably selecting modules (such as Heater, Mixer, RadFrac, etc.) and setting parameters, thereby handling complex multiphase flow and high solids content material flow.

[0086] S103. Retrieve the actual operating conditions and simulation results report for comparison, and repeat the previous step to obtain the final operating information of the mathematical model.

[0087] In this embodiment, the unit operation module used by the first water heater 11, the second water heater 12, the third water heater 13, the first flash evaporator 14, the vacuum flash evaporator 21, the vacuum flash separator 22, and the vacuum pump separator 24 in the coal-to-methanol ash water treatment system is Flash2, and the unit operation module used by the diverter 61 in the coal-to-methanol ash water treatment system is FSplit.

[0088] In the mathematical model constructed using Aspen Plus software, the operating temperature of the first water heater 11 is 180.04 degrees Celsius and the operating pressure is 1 MPa; the operating temperature of the second water heater 12 is 180.1 degrees Celsius and the operating pressure is 1 MPa; the operating temperature of the third water heater 13 is 126.08 degrees Celsius and the operating pressure is 0.23 MPa; the operating temperature of the first flash evaporator 14 is 170.1 degrees Celsius and the operating pressure is 0.86 MPa; the operating temperature of the vacuum flash evaporator 21 is 64.27 degrees Celsius and the operating pressure is 0.02 MPa; the operating temperature of the vacuum flash separator 22 is 39.3 degrees Celsius and the operating pressure is 0.2 MPa; the operating temperature of the vacuum pump separator 24 is 39.3 degrees Celsius and the operating pressure is 0.2 MPa; and the flow splitting ratio from the distributor 61 to the vacuum pump separator 24 is 0.67.

[0089] The unit operation modules used in the heater 32, condenser 42, and cooler 71 of the coal-to-methanol ash water treatment system are all Heater; the unit operation modules used in the vacuum pump 23 and drive pump 25 of the coal-to-methanol ash water treatment system are all Pump; the unit operation module used in the compressor 51 of the coal-to-methanol ash water treatment system is Compr; and the unit operation modules used in the first mixer 31, second mixer 41, and third mixer 52 of the coal-to-methanol ash water treatment system are all Mixer.

[0090] In the mathematical model constructed using Aspen Plus software, the operating temperature of heater 32 is 171.29 degrees Celsius and the operating pressure is 0.86 MPa; the operating temperature of condenser 42 is 39.29 degrees Celsius and the operating pressure is 0.018 MPa; the operating temperature of cooler 71 is 39.3 degrees Celsius and the operating pressure is 0.018 MPa; the outlet pressure of vacuum pump 23 and drive pump 25 is 0.1 MPa; compressor 51 is of type Isentropic and the outlet pressure of compressor 51 is 0.1 MPa; and the pressure drop of the first mixer 31, the second mixer 41, and the third mixer 52 is 0.

[0091] S104. Adjust at least some of the operating parameters of the mathematical model to obtain the target result report.

[0092] S105. Determine whether the target result meets the requirements.

[0093] S106. If so, adjust the actual operating parameters of the coal-to-methanol ash water treatment system based on the target result report.

[0094] Example 1: When optimizing the pH control of ash water treatment, the pH value of the ash water is controlled by adjusting the amount of alkaline substances (such as NaOH or lime) added to the ash water treatment, usually between 7 and 9, to ensure that the precipitation reaction proceeds fully and to prevent equipment corrosion.

[0095] Simulation results show that: low pH (e.g., pH < 7) may lead to incomplete precipitation, high suspended solids concentration, and increased load on subsequent filtration or centrifugation. High pH (e.g., pH > 9) may lead to excessive precipitation, generating excessive solid waste and increasing chemical consumption. At the optimal pH (e.g., pH = 8), precipitation is most effective, suspended solids concentration is lowest, and solid waste generation is moderate.

[0096] Therefore, by using simulation results, the amount of alkaline substance added can be adjusted to control the pH value of the greywater within the optimal range (e.g., pH=8). Optimization can reduce chemical consumption, lower solid waste treatment costs, and improve greywater treatment efficiency.

[0097] Example 2: When optimizing the temperature of ash water treatment, the temperature of the ash water entering the treatment system is adjusted to optimize the sedimentation reaction rate and solid separation efficiency.

[0098] According to simulation results: At low temperatures (e.g., 20℃): the precipitation reaction rate is slow, which may lead to longer processing time. At high temperatures (e.g., 60℃): the precipitation reaction rate is faster, but may increase energy consumption and the risk of equipment corrosion. At the optimal temperature (e.g., 40℃): the reaction rate is moderate, energy consumption is low, and processing efficiency is high.

[0099] Based on the simulation results, the operating conditions of the ash water preheater were adjusted to control the temperature within the optimal range (e.g., 40℃). Optimization improves processing efficiency, reduces energy consumption, and lowers equipment maintenance costs.

[0100] Example 3 optimizes the amount of flocculant added, which is used to adjust the amount of flocculant (such as polyacrylamide) added to improve the flocculation effect of suspended solids and increase the solid-liquid separation efficiency.

[0101] Based on simulation results: Low addition levels result in poor flocculation and low suspended solids removal rate. High addition levels improve flocculation but may lead to flocculant waste and increased costs. The optimal addition level achieves the highest suspended solids removal rate with a moderate flocculant dosage.

[0102] Based on the simulation results, the amount of flocculant added can be optimized to maximize suspended solids removal efficiency while controlling costs. Optimization reduces flocculant consumption and lowers operating costs.

[0103] Example 4: Optimization of ash water circulation rate to control the ash water circulation rate (i.e., the proportion of ash water reused after treatment), reduce fresh water consumption, and avoid the accumulation of impurities in the circulating ash water.

[0104] Based on simulation results: A low circulation rate leads to high fresh water consumption and increased operating costs. A high circulation rate may cause impurities to accumulate, affecting system stability. The optimal circulation rate maximizes the greywater reuse ratio while ensuring system stability.

[0105] Based on the simulation results, the greywater circulation rate can be adjusted to balance fresh water consumption and system stability. Optimization can reduce water consumption and wastewater discharge.

[0106] This embodiment uses Aspen Plus to simulate and adjust key parameters of the greywater treatment system (such as pH, temperature, flocculant dosage, and circulation rate), which can optimize process performance, reduce operating costs, and provide guidance for modifications in practical applications. The simulation results can help engineers develop more efficient and economical operating strategies while reducing trial-and-error costs.

[0107] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to 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 invention.

[0108] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0109] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0110] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0111] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A coal-to-methanol ash water treatment system, characterized in that, include: The first water heater has its inlet connected to the quench chamber of the gasifier so that the ash water discharged from the quench chamber is fed into the first water heater. The second water heater has its inlet connected to the scrubbing tower of the gasification section so that the grey water discharged from the scrubbing tower is fed into the second water heater. The first flash evaporator has its inlet connected to the gas outlet of the first water heater and the gas outlet of the second water heater, so that the steam in the first water heater and the second water heater is fed into the first flash evaporator for flash separation. The third water heater has its inlet connected to the outlets of the first and second water heaters, so that the bottom liquid in the first and second water heaters is transported into the third water heater. A vacuum flash evaporation device includes a vacuum flash evaporator, a vacuum flash separator, a vacuum pump, and a vacuum pump separator. The inlet of the vacuum flash evaporator is connected to the third water heater to deliver the bottom liquid of the third water heater into the vacuum flash evaporator. The outlet of the vacuum flash evaporator is connected to the inlet of the vacuum flash separator. The outlet of the vacuum flash separator is connected to the vacuum pump. Part of the condensate discharged by the vacuum pump mixes with the steam discharged from the outlet of the vacuum flash separator and is then delivered into the vacuum pump separator. Another part of the condensate discharged by the vacuum pump is delivered to a deoxygenated water tank. The outlet of the vacuum pump separator is connected to the inlet of the vacuum flash separator so that the bottom liquid of the vacuum pump separator flows back into the vacuum flash separator.

2. The coal-to-methanol ash water treatment system according to claim 1, characterized in that, The inlet end of the first flash evaporator is connected to a first mixer and a heater. The steam discharged from the outlet of the first water heater and the outlet of the second water heater enters the heater after passing through the first mixer, so as to exchange heat with the feed water of the washing tower before entering the first flash evaporator.

3. The coal-to-methanol ash water treatment system according to claim 1, characterized in that, A second mixer and a condenser are provided between the outlet of the vacuum flash evaporator and the inlet of the vacuum flash separator. The steam discharged from the outlet of the vacuum flash evaporator is condensed by the second mixer and the condenser in sequence before entering the vacuum flash separator.

4. The coal-to-methanol ash water treatment system according to claim 3, characterized in that, The outlet of the vacuum flash separator is connected to a compressor and a third mixer. The vacuum pump is connected to the third mixer. The steam discharged from the outlet of the vacuum flash separator passes through the compressor and is mixed with part of the condensate discharged by the vacuum pump in the third mixer and then transported into the vacuum pump separator.

5. The coal-to-methanol ash water treatment system according to claim 4, characterized in that, The outlet end of the vacuum pump is connected to a distributor, which is used to deliver the condensate discharged by the vacuum pump to the deoxygenation water tank and the vacuum pump separator respectively according to a preset ratio. A drive pump is provided between the distributor and the vacuum pump separator.

6. The coal-to-methanol ash water treatment system according to claim 1, characterized in that, The inlet of the vacuum flash evaporator is connected to the slag pool to transport the slag water in the slag pool into the vacuum flash evaporator. And / or, a cooler is provided between the liquid outlet of the vacuum pump separator and the liquid inlet of the vacuum flash separator.

7. An optimization method, characterized in that, An optimization method for the coal-to-methanol ash water treatment system as described in any one of claims 1 to 6, the optimization method comprising: A mathematical model was constructed using Aspen Plus software based on the aforementioned coal-to-methanol ash water treatment system. Given the runtime information, run the mathematical model and obtain a simulation results report; The actual operating conditions are retrieved and compared with the simulation results report. The previous step is repeated to obtain the final operating information of the mathematical model. Adjust at least some of the operating parameters of the mathematical model to obtain the target result report; Determine whether the target result meets the requirements; If so, the actual operating parameters of the coal-to-methanol ash water treatment system shall be adjusted based on the target result report.

8. The optimization method according to claim 7, characterized in that, The steps involve constructing a mathematical model using Aspen Plus software, including: Based on the composition of substances flowing into the first and second water heaters, the RKSOAVE property method used by the Aspen Plus software is determined. Based on the physical properties and process requirements of each device in the coal-to-methanol ash water treatment system, select the corresponding unit operation module in the Aspen Plus software. Based on the characteristics of heat flow, material flow and power flow in the coal-to-methanol ash water treatment system, the corresponding thermodynamic model and property database are selected in the Aspen Plus software.

9. The optimization method according to claim 8, characterized in that, In the final operating information, the unit operation module used by the first water heater, second water heater, third water heater, first flash evaporator, vacuum flash evaporator, vacuum flash separator and vacuum pump separator in the coal-to-methanol ash water treatment system is Flash2, and the unit operation module used by the diverter in the coal-to-methanol ash water treatment system is FSplit. In the mathematical model constructed using Aspen Plus software, the operating temperature of the first water heater is 180.04 degrees Celsius and the operating pressure is 1 MPa; the operating temperature of the second water heater is 180.1 degrees Celsius and the operating pressure is 1 MPa; the operating temperature of the third water heater is 126.08 degrees Celsius and the operating pressure is 0.23 MPa; the operating temperature of the first flash evaporator is 170.1 degrees Celsius and the operating pressure is 0.86 MPa; the operating temperature of the vacuum flash evaporator is 64.27 degrees Celsius and the operating pressure is 0.02 MPa; the operating temperature of the vacuum flash separator is 39.3 degrees Celsius and the operating pressure is 0.2 MPa; the operating temperature of the vacuum pump separator is 39.3 degrees Celsius and the operating pressure is 0.2 MPa; and the flow splitting ratio from the distributor to the vacuum pump separator is 0.

67.

10. The optimization method according to claim 9, characterized in that, The unit operation module used for the heater, condenser, and cooler in the coal-to-methanol ash water treatment system is Heater; the unit operation module used for the vacuum pump and drive pump in the coal-to-methanol ash water treatment system is Pump; the unit operation module used for the compressor in the coal-to-methanol ash water treatment system is Compr; and the unit operation module used for the first mixer, second mixer, and third mixer in the coal-to-methanol ash water treatment system is Mixer. In the mathematical model constructed using Aspen Plus software, the heater operates at a temperature of 171.29 degrees Celsius and an operating pressure of 0.86 MPa; the condenser operates at a temperature of 39.29 degrees Celsius and an operating pressure of 0.018 MPa; the cooler operates at a temperature of 39.3 degrees Celsius and an operating pressure of 0.018 MPa; the vacuum pump and drive pump both have an outlet pressure of 0.1 MPa; the compressor is of type Isentropic; the compressor's outlet pressure is 0.1 MPa; and the pressure drops of the first mixer, the second mixer, and the third mixer are all 0.

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