Method for resource utilization of petroleum refining stripping purification water sewage

Abstract

The present application relates to sewage treatment technical field, disclose a kind of oil refining stripping purification water sewage resource utilization method, the method comprises the following steps: refinery sulfur-containing ammonia-containing acidic water is divided into high phenolic acidic water and low phenolic acidic water according to the concentration of volatile phenol contained;The high phenolic acidic water is treated by first stripping, and high phenolic stripping purification water is obtained;The low phenolic acidic water is treated by second stripping, and low phenolic stripping purification water is obtained;The high phenolic stripping purification water and low phenolic stripping purification water are respectively reused.The present application adopts high phenolic stripping purification water and low phenolic stripping purification water stripping purification water source head quality collection and double-tower device quality processing, realizes the quality direct reuse mode of high water high use low water low use, system improves the stripping purification water sewage resource utilization efficiency of refinery, realizes the maximum utilization of refinery stripping purification water sewage resource.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for the resource utilization of wastewater from petroleum refining stripping purification. Background Technology

[0002] When refining sulfur-containing crude oil, processes such as atmospheric and vacuum distillation, catalytic cracking, delayed coking, and hydrorefining all discharge large amounts of acidic water (sulfur- and ammonia-containing wastewater). Acidic water accounts for the largest proportion of total refinery process wastewater discharge, reaching over 60% of the total. Most Chinese refineries use stripping to treat acidic water. Hydrogen sulfide and ammonia in the wastewater are removed and recovered through stripping, and the recovered hydrogen sulfide is used to recover sulfur through a sulfur recovery unit. Compared to the untreated acidic water, the stripped purified water has significantly reduced sulfur and nitrogen content and possesses advantages such as low hardness and low salinity, making it feasible for cascade utilization and reuse processes to achieve water conservation and emission reduction. However, because the stripped purified water contains pollutants such as phenols, sulfides, and ammonia nitrogen, it is still considered refining wastewater.

[0003] Stripping purification water is the largest point source wastewater discharged during the petroleum refining process, with a unit discharge volume of approximately 0.2 m³. 3 / t crude oil. Stripping wastewater requires close attention due to its large volume, and the green enterprise evaluation standards specifically include a water efficiency performance indicator for the reuse rate of sulfur-containing wastewater. Therefore, a special project on wastewater resource utilization must be carried out to ensure compliance. The reuse rate of sulfur-containing wastewater depends on the amount of stripping wastewater reused in the oil refining process. Stripping wastewater that is directly discharged into the wastewater treatment plant without being reused contributes nothing to the water efficiency performance of the sulfur-containing wastewater reuse rate. Therefore, the efficiency of wastewater resource utilization from stripping wastewater depends entirely on the amount of stripping wastewater reused in the oil refining process.

[0004] Currently, the only way to utilize stripping water in refinery projects both domestically and internationally is through direct reuse, primarily for feedwater in electrostatic precipitation (ESP) processes. However, due to the upper limit on water consumption in ESP, the reuse rate of stripping water is usually difficult to exceed 50%. To address increasingly stringent water quota restrictions and the need to improve the reuse rate of sulfur-containing wastewater, the question of whether catalytic cracking flue gas desulfurization units, which have significant process water demands in refineries, can utilize stripping water to replace fresh water and achieve water conservation and emission reduction is gradually gaining attention in the industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem of low recycling rate of stripping purified water in existing technologies and to provide a method for the resource utilization of stripping purified water wastewater in petroleum refining. This invention collects stripping purified water separately from the source based on the difference in volatile phenol concentration. Based on the dual stripping towers in the refinery equipment, a whole-plant stripping purified water wastewater resource utilization system is constructed to achieve separate collection, parallel treatment by the dual stripping units, and direct reuse of the separated water. This can optimize and improve the wastewater resource utilization rate of stripping purified water in the whole plant, reduce the risk of scaling and blockage in process pipelines and equipment, and ensure the long-term stable operation of the process equipment.

[0006] To achieve the above objectives, the present invention provides a method for the resource utilization of wastewater from petroleum refining stripping purification, the method comprising the following steps:

[0007] The sulfur-containing and amino acid-containing water from oil refineries is classified into high-phenolic acidic water and low-phenolic acidic water according to the concentration of volatile phenols it contains.

[0008] The high-phenolic acidic water is subjected to a first stripping treatment to obtain high-phenolic stripped purified water;

[0009] The low-phenolic acidic water is subjected to a second stripping treatment to obtain low-phenolic stripped purified water.

[0010] The high-phenol stripping purified water and the low-phenol stripping purified water are reused respectively.

[0011] Preferably, the concentration of volatile phenols in the high-phenolic acidic water is greater than 10 mg / L; the concentration of volatile phenols in the low-phenolic acidic water is not greater than 10 mg / L.

[0012] Preferably, the high-phenolic acidic water originates from sulfur-containing and amino acid-containing water generated by at least one of the following refining process units: atmospheric and vacuum distillation unit, catalytic cracking unit, catalytic reforming unit, and solvent regeneration unit.

[0013] Preferably, the low-phenolic acidic water originates from sulfur-containing and amino acid-containing water produced by at least one hydrorefining process unit in an oil refinery;

[0014] Preferably, the hydrogenation unit includes a residue oil hydrogenation unit, a diesel oil hydrogenation unit, and a wax oil hydrogenation unit.

[0015] Preferably, the high-phenol stripping purified water is directly reused in at least one of the following refining processes: atmospheric and vacuum distillation unit, catalytic cracking unit, catalytic reforming unit, and solvent regeneration unit.

[0016] Preferably, if the amount of high-phenol stripping purified water is insufficient, low-phenol stripping purified water, fresh water, or demineralized water may be used to supplement it, with low-phenol stripping purified water being the preferred choice.

[0017] Preferably, the high-phenol stripping purified water and / or low-phenol stripping purified water used for the atmospheric and vacuum desalination injection are monitored to ensure that the water quality has a pH value of 6.5-8.5, suspended solids of no more than 5 mg / L, and total hardness as CaCO3 of no more than 140 mg / L.

[0018] Preferably, the low-phenol stripping purified water is directly recycled to at least one of the following refining process units: a non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas, a residue hydrotreating unit, a diesel hydrotreating unit, and a wax oil hydrotreating unit.

[0019] Preferably, the non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas uses low-phenol stripping purified water as the makeup water for the scrubbing circulating liquid.

[0020] Preferably, the water quality of the low-phenol stripping purified water used in the non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas is monitored to ensure that the concentration of volatile phenols in the low-phenol stripping purified water does not exceed 10 mg / L, the concentration of TOC does not exceed 10 mg / L, and the concentration of oil does not exceed 1 mg / L.

[0021] Preferably, if the amount of the low-phenol stripping purified water is insufficient, low-hardness fresh water is used to supplement it.

[0022] Preferably, the hydrogen sulfide content of the high-phenol stripping purified water is ≤20mg / L, and the ammonia nitrogen content (calculated as N) is ≤50mg / L.

[0023] Preferably, the hydrogen sulfide content of the low-phenol stripping purified water is ≤20mg / L, and the ammonia nitrogen content (calculated as N) is ≤50mg / L.

[0024] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0025] (1) This invention utilizes the difference in volatile phenol concentration in sulfur-containing and amino acid-containing water generated by the process equipment of the oil refinery, and matches the water quality control index requirements for volatile phenol organic pollution in the process equipment that uses stripped purified water as production water. It adopts separate collection of high-phenol stripped purified water and low-phenol stripped purified water at the source and separate treatment in a dual-tower unit, realizing the separate direct reuse of stripped purified water with high water content and low water content. This enhances the overall reuse efficiency of stripped purified water, which has a dominant volume of wastewater in the refinery, and can optimize and improve the wastewater resource utilization rate of stripped purified water in the whole plant. It can also make full use of the low hardness of stripped purified water, reduce the risk of scaling and blockage in process pipelines and equipment, ensure the long-term stable operation of the process equipment, and maximize the utilization of wastewater resources of stripped purified water in the refinery.

[0026] (2) The method for resource utilization of stripping water wastewater in petroleum refining enterprises proposed in this invention follows the principle of reasonable matching of water quality and quantity between "water source" and "water trap" in wastewater resource utilization. Based on the different concentrations of volatile phenols in sulfur-containing and amino acid-containing water generated by refinery process units and the different requirements of process units using stripping water as production water for the control indicators of volatile phenol organic pollution in production water, the entire process of the generation source and reuse terminal of stripping water in petroleum refining enterprises is systematically optimized. The method adopts the technical approach of separate collection of high-phenol stripping water and low-phenol stripping water at the source, parallel operation of dual stripping units, and direct reuse of separate stripping water, so that the lower-phenol stripping water with better water quality can be reused for water quality improvement. For hydrogen production processes such as non-regenerative wet scrubbing desulfurization units for catalytic cracking flue gas, residue hydrogenation, diesel hydrogenation, and wax oil hydrogenation, which require higher standards, high-phenol stripping purified water is preferentially reused in processes with relatively lower water quality requirements, such as electrostatic desalination, atmospheric and vacuum distillation, and catalytic cracking. When the reuse of high-phenol stripping purified water still does not meet the water volume requirements of the process units, low-phenol stripping purified water with better water quality is reused in process units with lower water quality requirements. This further improves the overall resource utilization efficiency of stripping purified water. The entire system of stripping purified water generation and resource utilization in the refinery is systematically optimized from the source, intermediate treatment and terminal reuse, so as to maximize the resource utilization of stripping purified water in the entire refinery and achieve water conservation, emission reduction and green development.

[0027] (3) This invention fully utilizes the existing facilities of two stripping towers conventionally configured in large-scale refineries, eliminating the need for additional investment in stripping purification water treatment and reuse projects. It only requires the separate collection of high-phenol and low-phenol stripping purification water during system construction and operation, with parallel operation of the dual stripping units and direct reuse of the separated water, thus optimizing the overall plant's wastewater resource utilization rate. The entire system operation requires only one conventional unit operation: the acidic water stripping process. The process flow is concise, operation control is simple and reliable, the required dosage of chemicals is low, and it does not cause secondary pollution to the stripping purification water. This reduces the refinery's unit fresh water consumption for crude oil and wastewater discharge, alleviates the hydraulic and pollution loads on wastewater treatment facilities, and provides strong technical support for reducing the cost of feedwater treatment and wastewater reuse in petroleum refining enterprises and improving their water performance compliance rate. This invention can also guide refineries with only a single stripping tower to design and construct a second stripping tower. Furthermore, during the construction and operation of the system, it enables the separate collection of high-phenol stripping purified water and low-phenol stripping purified water. With the parallel operation of the dual stripping units and direct reuse of the separated water, the wastewater resource utilization rate of the entire plant's stripping purified water can be significantly improved. Attached Figure Description

[0028] Figure 1 A process flow diagram of refinery stripping purification water treatment provided in one embodiment of the present invention. Detailed Implementation

[0029] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0030] Through field trials conducted in petroleum refining enterprises to directly reuse stripping purified water in flue gas desulfurization (FGD) units, it was discovered that all trials using high-phenolic water stripping purified water for FGD unit reuse could not guarantee the normal operation of the FGD process. Only by using low-phenolic acidic water stripping purified water for FGD unit reuse could stripping purified water replace fresh water and achieve long-term stable operation of the process. Therefore, the inventors unexpectedly discovered that matching the phenol concentration of the stripping purified water to the different refining and chemical processes' water requirements could improve the resource utilization efficiency of stripping purified water wastewater.

[0031] This invention provides a method for the resource utilization of wastewater from petroleum refining stripping purification, the method comprising the following steps:

[0032] The sulfur-containing and amino acid-containing water from oil refineries is classified into high-phenolic acidic water and low-phenolic acidic water according to the concentration of volatile phenols it contains.

[0033] The high-phenolic acidic water is subjected to a first stripping treatment to obtain high-phenolic stripped purified water;

[0034] The low-phenol acidic water is subjected to a second stripping treatment to obtain low-phenol stripped purified water.

[0035] The high-phenol stripping purified water and the low-phenol stripping purified water are reused respectively.

[0036] This invention utilizes the varying concentrations of volatile phenols in sulfur- and amino acid-containing water generated by oil refinery processes, and the differing control requirements for volatile phenol organic pollution in production water using stripping purified water. It optimizes the entire process of stripping purified water generation and reuse in oil refining enterprises by employing a technology that separates high-phenol and low-phenol stripping purified water at the source, operates dual stripping processes in parallel, and directly reuses the separated water. This achieves a separate, direct reuse method for high-water, high-use, and low-water, significantly improving the resource utilization efficiency of stripping purified water in oil refineries. It enhances the overall reuse efficiency of stripping purified water, which constitutes a dominant volume of refinery wastewater, optimizing the overall resource utilization rate of stripping purified water throughout the plant. Furthermore, it fully leverages the low hardness of stripping purified water, reducing the risk of scaling and blockage in process pipelines and equipment, and ensuring the long-term stable operation of the process units.

[0037] The present invention provides a method for the differentiated resource utilization of stripping water in oil refineries. This method addresses the sulfur- and amino acid-containing water discharged from the source of stripping water—the acidic water—based on its varying concentrations of volatile phenols. The water is collected separately and sent to two stripping units for treatment. Then, based on the water quality requirements of the stripping water for process injection or production makeup water in the oil refinery, the stripping water is directly reused, maximizing the overall resource utilization rate of the plant's stripping water. This invention fully utilizes the existing facilities of two conventionally configured stripping towers in large refineries, eliminating the need for additional investment in stripping water treatment and reuse projects. The system only requires differentiated collection of high-phenol and low-phenol stripping water during construction and operation, with parallel operation of the two stripping units and direct reuse of the differentiated water, thus optimizing the overall resource utilization rate of the plant's stripping water. The entire system requires only one conventional unit operation: the acidic water stripping process. The process flow is concise, operation and control are simple and reliable, and the required reagent dosage is low, without causing secondary pollution to the stripping purified water. This reduces the refinery's unit fresh water consumption for crude oil and wastewater discharge, alleviating the hydraulic and pollution loads on wastewater treatment facilities. It provides strong technical support for reducing refinery feedwater treatment and wastewater reuse costs and improving refinery water performance compliance rates. This invention can also guide refineries with only a single stripping tower in designing and constructing a second stripping tower. Furthermore, by implementing separate collection of high-phenol and low-phenol stripping purified water during system construction and operation, and allowing the parallel operation of the two stripping units with direct separate reuse, the overall wastewater resource utilization rate of the plant's stripping purified water can be significantly improved.

[0038] Research has revealed that the sulfur-containing and amino acid-containing water of this invention mainly originates from the acidic water produced by process units such as atmospheric and vacuum distillation, catalytic cracking, catalytic reforming, solvent regeneration, residue hydrotreating, diesel hydrotreating, and wax oil hydrotreating in oil refineries. Among these, the sulfur-containing and amino acid-containing water produced by atmospheric and vacuum distillation, catalytic cracking, catalytic reforming, and solvent regeneration units has a high concentration of volatile phenols, while the sulfur-containing and amino acid-containing water produced by hydrogenation units such as residue hydrotreating, diesel hydrotreating, and wax oil hydrotreating units has a low concentration of volatile phenols.

[0039] In some embodiments of the present invention, the concentration of volatile phenols in the high-phenolic acidic water is greater than 10 mg / L; the concentration of volatile phenols in the low-phenolic acidic water is not greater than 10 mg / L.

[0040] Through extensive research, the inventors discovered that acidic water stripping units generally cannot remove volatile phenols. Furthermore, the volatile phenol concentration in the stripping purified water reused by catalytic cracking desulfurization units, major water users in refineries, cannot exceed 10 mg / L; otherwise, the desulfurization unit will foam and malfunction. However, reusing stripping purified water with a volatile phenol concentration below 10 mg / L not only allows the unit to operate normally and reduces wastewater discharge, but also, due to the low salt and low hardness characteristics of the stripping purified water, significantly reduces scaling. Compared to using fresh water with higher hardness, the unit can operate stably for extended periods. Therefore, acidic water was categorized into high-phenol and low-phenol types at the source, and a separate collection method was adopted. Using a 10 mg / L threshold to classify the volatile phenol concentration in acidic water maximizes the reuse rate of stripping purified water.

[0041] The proposed method for the resource utilization of stripping and purification wastewater in petroleum refining enterprises follows the principle of reasonable matching of water quality and quantity between "water source" and "water trap" in wastewater resource utilization. Based on the different concentrations of volatile phenols in sulfur-containing and amino acid-containing water generated by refinery process units and the different control requirements for volatile phenol organic pollution in production water of process units using stripping and purification water as production water, the method uses a volatile phenol concentration of 10 mg / L in acidic water as the dividing point between high-phenol acidic water and low-phenol acidic water, and optimizes the entire process from the source of stripping and purification water generation to the end of reuse in petroleum refining enterprises.

[0042] This invention collects stripped water from the source based on differences in volatile phenol concentration. Using a dual stripping tower in a refinery as a foundation, it constructs a plant-wide stripped water wastewater resource utilization system. This system employs a method of separate collection, parallel treatment, and direct reuse of stripped water. Utilizing existing dual stripping units, it builds a plant-wide stripped water treatment and reuse system. The system matches the differences in volatile phenol concentrations in sulfur- and amino acid-containing water generated by refinery processes with the water quality control requirements for volatile phenol organic pollution in production water used by processes employing stripped water. This system optimizes and improves the resource utilization efficiency of stripped water, achieving water conservation and emission reduction in the refinery.

[0043] In some embodiments of the present invention, the high-phenolic acidic water originates from sulfur-containing and amino acid-containing water generated by at least one of the following refining process units: atmospheric and vacuum distillation unit, catalytic cracking unit, catalytic reforming unit, and solvent regeneration unit.

[0044] In some embodiments of the present invention, the low-phenolic acidic water is derived from sulfur-containing and amino acid-containing water produced by at least one hydrorefining process unit in an oil refinery.

[0045] The hydrogenation devices in this invention include, but are not limited to, residue oil hydrogenation devices, diesel oil hydrogenation devices, and wax oil hydrogenation devices.

[0046] In this invention, the sources of high-phenolic acidic water and low-phenolic acidic water can be adjusted according to the actual conditions of each refinery. Acidic water with a volatile phenol concentration greater than 10 mg / L is used as high-phenolic acidic water and undergoes the first stripping treatment; acidic water with a volatile phenol concentration not greater than 10 mg / L is used as low-phenolic acidic water and undergoes the second stripping treatment, and then is reused separately according to the conditions of each refinery.

[0047] This invention classifies sulfur- and amino acid-containing water from oil refineries into two types based on the varying concentrations of phenol contamination: high-phenol acidic water and low-phenol acidic water. Two independent acidic water collection networks are constructed for each type, and these networks are then fed to two separate stripping and purification units. The two units process the high-phenol acidic water and low-phenol acidic water respectively, producing high-phenol stripped purified water and low-phenol stripped purified water. The high-phenol stripped purified water and low-phenol stripped purified water then enter separate high-phenol stripped purified water reuse networks and low-phenol stripped purified water reuse networks, respectively. The high-phenol stripping purified water reuse network sends the high-phenol stripping purified water to process units such as atmospheric and vacuum distillation, catalytic cracking, catalytic reforming, and solvent regeneration, where the high-phenol stripping purified water can be directly reused. The low-phenol stripping purified water reuse network sends the low-phenol stripping purified water to process units such as catalytic cracking flue gas non-regenerative wet scrubbing desulfurization, residue oil hydrotreating, diesel oil hydrotreating, and wax oil hydrotreating, where the low-phenol stripping purified water can be directly reused. The two acid water collection networks do not have different technical requirements due to the different concentrations of volatile phenols in the acid water requiring stripping treatment. It is necessary to ensure that the high-phenol acid water collection network and the low-phenol acid water collection network are physically isolated, collecting high-phenol acid water and low-phenol acid water separately, and ensuring that the two collection networks operate independently. The two stripping purified water reuse networks are used to collect and transport stripping purified water produced by the two stripping units that meets the control requirements for hydrogen sulfide and ammonia nitrogen. There are no special technical requirements due to the different concentrations of volatile phenols in the stripping purified water. It is necessary to ensure that the high-phenol stripping purified water reuse network and the low-phenol stripping purified water reuse network are physically isolated and operate independently.

[0048] The stripping purification device used does not have different technical requirements due to the different concentrations of volatile phenols in the acidic water that needs to be stripped, nor does it have the technical requirements for removing volatile phenols in the stripping process. It only needs to meet the control requirements for hydrogen sulfide and ammonia nitrogen in the stripped purified water (hydrogen sulfide ≤20mg / L, ammonia nitrogen (as N) ≤50mg / L).

[0049] In some embodiments of the present invention, the high-phenol stripping purified water is directly reused in at least one of the following refining process units: atmospheric and vacuum distillation unit, catalytic cracking unit, catalytic reforming unit, and solvent regeneration unit.

[0050] The water injected into the atmospheric and vacuum distillation unit's electro-desalination process is prioritized for direct reuse of high-phenol stripping purified water. By extracting volatile phenols from crude oil, the overall phenol pollution emissions of the plant can be reduced.

[0051] In some embodiments of the present invention, when the amount of high-phenol stripping purified water is insufficient, low-phenol stripping purified water, fresh water, or demineralized water is used to supplement it, preferably low-phenol stripping purified water.

[0052] In this invention, when the amount of high-phenol stripping purified water is insufficient, low-phenol stripping purified water is preferred, and fresh water or demineralized water is avoided as much as possible.

[0053] In some embodiments of the present invention, the high-phenol stripping purified water and / or low-phenol stripping purified water used for the atmospheric and vacuum desalination injection are monitored to ensure that the pH value of the water is 6.5-8.5, the suspended solids do not exceed 5 mg / L, and the total hardness as CaCO3 does not exceed 140 mg / L.

[0054] In some embodiments of the present invention, the low-phenol stripping purified water is directly reused in at least one of the following refining process units: a non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas, a residue hydrotreating unit, a diesel hydrotreating unit, and a wax oil hydrotreating unit.

[0055] In some embodiments of the present invention, the non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas uses low-phenol stripping purified water as the makeup water for the scrubbing circulating liquid.

[0056] In some embodiments of the present invention, the water quality of the low-phenol stripping purified water used in the non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas is monitored to ensure that the concentration of volatile phenols, the concentration of TOC, and the concentration of oil in the low-phenol stripping purified water do not exceed 10 mg / L, 10 mg / L, and 1 mg / L, respectively.

[0057] In some embodiments of the present invention, if the amount of the low-phenol stripping purified water is insufficient, low-hardness fresh water is used to supplement it.

[0058] In this invention, the non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas, as well as hydrogen-containing units such as residue oil hydrogenation, diesel oil hydrogenation, and wax oil hydrogenation, can only directly reuse low-phenol stripping purified water. Under no circumstances is it permitted to directly reuse high-phenol stripping purified water. If the amount of low-phenol stripping purified water is insufficient, it should be supplemented with low-hardness fresh water.

[0059] This invention reuses lower-phenol stripping purified water, which has higher water quality requirements, in hydrogen production processes such as non-regenerative wet scrubbing desulfurization units for catalytic cracking flue gas, residue hydrogenation, diesel hydrogenation, and wax oil hydrogenation. Meanwhile, higher-phenol stripping purified water is preferentially reused in processes with relatively lower water quality requirements, such as electrostatic desalination, atmospheric and vacuum distillation, and catalytic cracking. When the reuse of higher-phenol stripping purified water still does not meet the water volume requirements of the process units, lower-phenol stripping purified water, which has higher water quality, is reused in processes with lower water quality requirements. This further improves the overall resource utilization efficiency of stripping purified water. The entire system of stripping purified water generation and resource utilization in the refinery is systematically optimized from the source, intermediate treatment, and final reuse, maximizing the resource utilization of stripping purified water throughout the refinery and achieving water conservation, emission reduction, and green development.

[0060] This invention does not impose any special restrictions on the first and second stripping processes. Conventional stripping methods and stripping towers can be used. It is only necessary to ensure that the stripped purified water produced by the stripping process meets the water quality control requirements for hydrogen sulfide and ammonia nitrogen (hydrogen sulfide ≤ 20 mg / L, ammonia nitrogen (as N) ≤ 50 mg / L).

[0061] In some embodiments of the present invention, the hydrogen sulfide contained in the high-phenol stripping purified water is ≤20mg / L, and the ammonia nitrogen contained in nitrogen is ≤50mg / L; the hydrogen sulfide contained in the low-phenol stripping purified water is ≤20mg / L, and the ammonia nitrogen contained in nitrogen is ≤50mg / L.

[0062] In a preferred embodiment of the present invention, the method specifically includes the following steps:

[0063] (1) Construct a high-phenolic acid water collection network and a low-phenolic stripping purified water reuse network connected to the first stripping purification unit; and construct a low-phenolic acid water collection network and a low-phenolic stripping purified water reuse network connected to the second stripping purification unit.

[0064] (2) The sulfur-containing and amino acid-containing water of the refinery is divided into high-phenol acid water and low-phenol acid water according to the concentration of volatile phenols contained therein; the high-phenol acid water and low-phenol acid water are respectively sent to the first stripping purification unit for high-phenol acid water stripping and the second stripping purification unit for low-phenol acid water stripping through two independent acid water collection pipelines.

[0065] (3) The high-phenolic acidic water collected by the high-phenolic acidic water collection network is subjected to the first stripping purification device for first stripping treatment to obtain high-phenolic stripped purified water, and then the high-phenolic stripped purified water is reused through the high-phenolic stripped purified water reuse network; the low-phenolic acidic water collected by the low-phenolic acidic water collection network is subjected to the second stripping purification device for second stripping treatment to obtain low-phenolic stripped purified water, and then the low-phenolic stripped purified water is reused through the low-phenolic stripped purified water reuse network.

[0066] The high-phenol stripping purified water reuse network can be connected to devices such as atmospheric and vacuum distillation units, catalytic cracking units, catalytic reforming units, and solvent regeneration units to realize the reuse of high-phenol stripping purified water. When the amount of high-phenol stripping purified water is insufficient, it can be supplemented with low-phenol stripping purified water, fresh water, or demineralized water, preferably low-phenol stripping purified water.

[0067] The low-phenol stripping purified water reuse network can be connected to devices such as catalytic cracking flue gas non-regenerative wet scrubbing desulfurization unit, residue oil hydrogenation unit, diesel oil hydrogenation unit, and wax oil hydrogenation unit to realize the reuse of low-phenol stripping purified water. When the amount of low-phenol stripping purified water is insufficient, low-hardness fresh water is used to supplement it.

[0068] In the method of the present invention, the concentration of volatile phenols in the sulfur-containing and amino acid-containing water of each unit of the refinery can be monitored to determine whether the water enters the high-phenol acid water collection network or the low-phenol acid water collection network. Each refinery can adjust the network according to its own actual situation.

[0069] This invention, based on the dual stripping towers of a refinery, constructs a plant-wide stripping purification water wastewater resource utilization system. It achieves separate collection, parallel treatment by the dual stripping units, and direct reuse of the separated wastewater, thereby optimizing and improving the overall wastewater resource utilization rate of the plant's stripping purification water. The entire stripping purification water resource utilization system requires no additional investment in stripping purification water treatment and reuse engineering. The process flow is simple, and operation and control are convenient and reliable. It can reduce the refinery's unit crude oil fresh water consumption and wastewater discharge, alleviate the hydraulic and pollution loads on wastewater treatment facilities, reduce refinery feedwater treatment and wastewater reuse costs, and improve the refinery's water performance compliance rate.

[0070] The technical solutions of the present invention will be clearly and completely described below through embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0071] Unless otherwise specified in the following examples and comparative examples, all conditions were performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available products.

[0072] A large oil refinery is equipped with two sets of sulfur- and amino acid-containing water stripping units. These units treat the sulfur- and amino acid-containing water generated from various process units across the plant, allowing some of the stripping water to be directly reused in the process units, thus achieving resource utilization of the stripping water wastewater. The stripping water that cannot be reused is discharged into a wastewater treatment plant. The overall stripping water reuse efficiency of the plant is less than 60%.

[0073] Example

[0074] Based on a systematic analysis of the entire process of stripping purified water generation and reuse, the method of this invention is used to optimize the aforementioned large-scale oil refinery in the prior art, such as... Figure 1 As shown, the specific steps are as follows:

[0075] (1) Through water quality analysis and testing, acidic water with a volatile phenol concentration of no more than 10 mg / L generated by hydrogen production processes such as residue oil hydrogenation, diesel oil hydrogenation, and wax oil hydrogenation is identified as low-phenol acidic water; acidic water with a volatile phenol concentration of more than 10 mg / L generated by other process units is identified as high-phenol acidic water.

[0076] (2) Low-phenolic acidic water generated by hydrogen production processes such as residue oil hydrogenation, diesel oil hydrogenation, and wax oil hydrogenation is specially collected by a low-phenolic acidic water collection pipeline network and sent to acidic water stripping tower I. After the first stripping treatment, the sulfide and ammonia nitrogen meet the standards (sulfide ≤20mg / L and ammonia nitrogen ≤50mg / L) to obtain low-phenolic stripped purified water.

[0077] (3) The low-phenol stripping purified water is directly recycled to various hydrogen production process units such as catalytic cracking flue gas desulfurization, residue oil hydrogenation, diesel oil hydrogenation, and wax oil hydrogenation, as well as the water seal of acid water stripping tower I.

[0078] (4) Process units such as atmospheric and vacuum distillation, catalytic cracking, and solvent regeneration (e.g.) Figure 1 The high-phenol acidic water produced (as shown) is collected by a special high-phenol acidic water collection pipeline network and sent to acidic water stripping tower II. After the second stripping treatment, the sulfide and ammonia nitrogen levels are ensured to meet the standards (sulfide ≤20mg / L and ammonia nitrogen ≤50mg / L), thus obtaining high-phenol stripped purified water.

[0079] (5) High-phenol stripping purified water can be directly reused in production processes such as desalination and catalytic cracking (e.g., Figure 1 (as shown) and the acidic water stripping tower II water seal, the high-phenol stripping purified water exceeding the amount used by each direct reuse process unit is discharged into the sewage treatment plant for treatment and then discharged in compliance with standards; among them, the high-phenol stripping purified water discharged into the sewage treatment plant is not included in the resource utilization of stripping purified water.

[0080] (6) The electro-desalination process can utilize crude oil extraction to recover volatile phenols from high-phenol stripping purification water. The removal rate of volatile phenols can reach more than 90%, thus reducing the volatile phenol pollution load entering the refinery wastewater treatment plant by 50 tons per year.

[0081] (7) When the volume of high-phenol stripping purified water cannot meet the water demand of processes such as atmospheric and vacuum distillation, catalytic cracking, and solvent regeneration, low-phenol stripping purified water can be reused in the processes that prioritize the use of high-phenol stripping purified water. This can save fresh water and improve the overall utilization rate of stripping purified water resources in the plant.

[0082] (8) Low-phenol stripping purified water exceeding the amount used in each direct reuse process unit is discharged into the sewage treatment plant for treatment and then discharged in compliance with standards. Low-phenol stripping purified water discharged into the sewage treatment plant is not included in the resource utilization of stripping purified water.

[0083] In the existing technology, the refinery did not consider the different concentrations of volatile phenols in the stripping purification water, did not collect acidic water separately, and adopted a mixed collection of acidic water produced by various process units. The operation of the two stripping units was evenly distributed according to the water volume, resulting in the phenol content of the produced water from the two acidic water stripping units being too high. Units with high requirements for production water quality, such as the non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas, could not directly reuse the stripping purification water. The overall stripping purification water reuse efficiency of the plant was less than 60%.

[0084] By adopting the optimization measures in the embodiments, the refinery increased the recycling rate of stripping purified water to over 95% without additional engineering investment, and utilized a total of 1.45 million cubic meters of stripping purified water annually. 3 Therefore, it saves approximately 1.45 million tons of fresh water and demineralized water, and reduces wastewater generation by 1.45 million cubic meters. 3 This reduces volatile phenol emissions by 50 tons. Low-phenol stripping purified water is used directly as makeup water for the alkali solution in the catalytic cracking flue gas desulfurization unit, replacing fresh water and saving 55 cubic meters of water. 3 The method produces a continuous flow of fresh water per hour, and because the hardness of the low-phenol stripped water is less than one-tenth of the hardness of the local fresh water, scaling and clogging in the equipment and pipelines are significantly reduced. Therefore, the method of this invention realizes the resource utilization of stripped water, improves wastewater resource utilization efficiency, achieves water conservation and emission reduction, and promotes green development.

[0085] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for the resource utilization of wastewater from petroleum refining stripping purification, characterized in that, The method includes the following steps: The sulfur-containing and amino acid-containing water from oil refineries is classified into high-phenolic acidic water and low-phenolic acidic water according to the concentration of volatile phenols it contains. The high-phenolic acidic water is subjected to a first stripping treatment to obtain high-phenolic stripped purified water; The low-phenolic acidic water is subjected to a second stripping treatment to obtain low-phenolic stripped purified water. The high-phenol stripping purified water and the low-phenol stripping purified water are reused separately. The high-phenol stripping purified water is directly reused in at least one of the following refining processes: atmospheric and vacuum distillation unit, catalytic cracking unit, catalytic reforming unit, and solvent regeneration unit. The low-phenol stripping purified water is directly reused in at least one of the following refining processes: a non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas, a residue hydrotreating unit, a diesel hydrotreating unit, and a wax oil hydrotreating unit; the concentration of volatile phenols in the high-phenol acidic water is greater than 10 mg / L. The concentration of volatile phenols in the low-phenol acidic water is no greater than 10 mg / L.

2. The method according to claim 1, wherein, The high-phenolic acidic water originates from sulfur- and amino acid-containing water produced by at least one of the following refining process units: atmospheric and vacuum distillation unit, catalytic cracking unit, catalytic reforming unit, and solvent regeneration unit.

3. The method according to claim 1 or 2, wherein, The low-phenolic acidic water is derived from sulfur-containing and amino acid-containing water produced by at least one hydrorefining process unit in an oil refinery.

4. The method according to claim 3, wherein, The hydrogenation unit includes a residue oil hydrogenation unit, a diesel oil hydrogenation unit, and a wax oil hydrogenation unit.

5. The method according to claim 1, wherein, If the amount of high-phenol stripping purified water is insufficient, low-phenol stripping purified water, fresh water, or demineralized water can be used to supplement it.

6. The method according to claim 5, wherein, If the amount of high-phenol stripping purified water is insufficient, low-phenol stripping purified water shall be used to supplement it.

7. The method according to claim 1, wherein, The water quality of the high-phenol stripping purified water and / or low-phenol stripping purified water used for the electrostatic desalination injection of the atmospheric and vacuum distillation unit is monitored to ensure that the pH value of the water is 6.5-8.5, the suspended solids do not exceed 5 mg / L, and the total hardness as CaCO3 does not exceed 140 mg / L.

8. The method according to claim 1, wherein, The non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas uses low-phenol stripping purified water as the makeup water for the scrubbing circulating liquid.

9. The method according to claim 8, wherein, Water quality monitoring is conducted on the low-phenol stripping purified water used in the non-regenerative wet scrubbing desulfurization unit for catalytic cracking flue gas to ensure that the concentration of volatile phenols, TOC, and oil in the low-phenol stripping purified water does not exceed 10 mg / L, TOC does not exceed 10 mg / L, and oil concentration does not exceed 1 mg / L.

10. The method according to claim 1, wherein, If the amount of the low-phenol stripping purified water is insufficient, supplement it with fresh water of low hardness.

11. The method according to claim 1, wherein, The hydrogen sulfide content of the high-phenol stripping purified water is ≤20mg / L, and the ammonia nitrogen content (calculated as N) is ≤50mg / L; The low-phenol stripping purified water contains ≤20mg / L of hydrogen sulfide and ≤50mg / L of ammonia nitrogen (calculated as N).

Images