Zero-discharge recycling process for petroleum cracking catalyst production sewage

Abstract

The invention relates to the technical field of sewage treatment, in particular to a petroleum cracking catalyst production sewage zero-discharge recycling process which comprises the steps that petroleum cracking catalyst production sewage is subjected to sewage treatment to obtain recycled water and sludge, the sludge is filtered through a plate and frame filter, and sewage treatment comprises sewage pretreatment, reverse osmosis treatment and MVR evaporator treatment in sequence; the reuse water is divided into two parts, one part enters a production water system to be reused, and the other part enters a fire fighting water system to be reused; the sewage pretreatment comprises flocculation treatment and silicon removal treatment, and the precipitated supernatant after flocculation is reused as dosing production water in the silicon removal treatment. According to the invention, zero discharge of sewage and comprehensive recycling of reuse water are realized, consumption of production water is reduced, resources are saved, and economic benefits are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of sewage treatment, and in particular to a zero-discharge reuse process for wastewater produced by petroleum cracking catalysts. Background Art

[0002] With the growing demand for water resources, the use of produced water has become particularly important. In the manufacturing of petroleum cracking catalysts, produced water is widely used for cooling, washing and process. The use of produced water also faces some challenges and problems. The cost of produced water is relatively high, requiring a lot of capital and technical support. Secondly, some by-products and wastes may be generated in the process of produced water, which need to be properly handled to avoid pollution to the environment. The sustainability and long-term stability of produced water are also issues that need to be considered. In order to solve these problems, it is necessary to further strengthen technological research and development and innovation to improve the efficiency and quality of produced water.

[0003] The 156t / h sewage treatment device of the raw material and power department was originally designed to produce two streams of recycled water, one of which is the secondary RO (reverse osmosis) water produced by gel and microspheres, with a total maximum volume of 83.96m 3 / h, one stream is distilled water produced by condensation after MVR evaporation and heat exchange of gel and microspheres, with a total maximum of 55.12m 3 / h, so the maximum amount of recycled water produced by a 156t / h sewage treatment plant is 139.08m 3 / h. The original design of the recycled water delivery process is divided into two routes: one route is sent to the raw water tank of the desalted water station as the water inlet of the desalted water unit, and the other route is sent to the sewage treatment device discharge pool if the desalted water cannot be fully reused.

[0004] Its technical defect is that the recycled water is directly sent to the raw water tank of the desalted water station and used as the inlet water for the desalted water. However, in the actual operation process, due to the small actual water consumption of the desalted water, it is impossible to effectively balance the flow of this recycled water, resulting in a large amount of high-quality water being discharged into the external discharge pool, causing a waste of resources. In addition, the ammonia nitrogen component contained in the recycled water requires the desalted water station to frequently regenerate the yin and yang beds during use, increasing maintenance costs. Finally, since the water supply of the water plant is affected by seasonal changes, especially in dry and rainy weather conditions, the inventory of the water plant will be significantly insufficient, resulting in a reduction in water delivery or even a cessation of water supply, which has a serious impact on the normal production of the device. Summary of the invention

[0005] In view of the technical problem of wasteful discharge of recycled water obtained from sewage treatment, the present invention provides a zero-discharge and reuse process for petroleum cracking catalyst production wastewater, which achieves zero discharge of sewage and comprehensive recycling of recycled water, reduces production water consumption and saves resources.

[0006] The invention provides a zero-discharge reuse process for wastewater produced by a petroleum cracking catalyst, comprising: obtaining reuse water and sludge by treating wastewater produced by a petroleum cracking catalyst, filtering the sludge by a plate and frame filter, and sequentially performing wastewater pretreatment, adsorption treatment, reverse osmosis treatment, and MVR evaporator treatment. The reuse water is divided into two parts, one of which enters a production water system for reuse, and the other enters a fire water system for reuse; the wastewater pretreatment comprises flocculation treatment and silicon removal treatment, and the supernatant of the precipitated water after flocculation is reused as doped production water in the silicon removal treatment.

[0007] Furthermore, the reverse osmosis treatment adopts a two-stage reverse osmosis system, and the recycled water entering the production water system for reuse comes from the secondary reverse osmosis water produced by the two-stage reverse osmosis system. The conductivity of the secondary reverse osmosis water produced is <10μs / cm, and the secondary reverse osmosis water produced is temporarily stored in a recycled water tank.

[0008] Furthermore, the recycled water stored in the recycled water tank is passed into the pump cooling device of the MVR evaporator as cooling water for reuse, and the outlet water of the cooling device is returned to the recycled water tank.

[0009] Furthermore, the recycled water entering the fire water system comes from the distilled water condensed after the MVR evaporator processes the MVR evaporation.

[0010] Furthermore, the additives used in the desiliconization treatment include sodium carbonate, magnesium and lime.

[0011] Furthermore, a sewage treatment device is used to treat sewage. The sewage treatment device is provided with a water pipe gallery, and the water inlet of the water pipe gallery is connected to the production water system through a cross-line pipeline.

[0012] Furthermore, a ball valve and a check valve are provided on the cross-line pipeline, and a pressure gauge is provided in the water pipe gallery. The pressure gauge is electrically connected to the control system, and the control system is electrically connected to the ball valve.

[0013] Furthermore, the sewage treatment device is provided with a circulating water station, and the circulating water station is replenished with domestic water.

[0014] Furthermore, the wastewater produced by the wastewater pretreatment is reused as cloth washing water for the plate and frame filter.

[0015] The beneficial effects of the present invention are as follows: the present invention is applied to the wastewater treatment process of petroleum catalytic cracking materials. By improving the existing pipelines, process flow, etc., the recycled water obtained after the treatment of the wastewater produced by the petroleum cracking catalyst can be introduced into the production water system and the fire water system for reuse, and at the same time, the supernatant after flocculation and precipitation is reused as the dosing production water in the pretreatment, thereby achieving zero discharge of wastewater and comprehensive recycling of recycled water, reducing production water consumption, saving resources, and having economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 It is a process flow chart of a specific implementation mode of the present invention. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0019] Example 1 Combination Figure 1 The present invention provides a method for treating wastewater produced by petroleum cracking catalysts, including: treating wastewater produced by petroleum cracking catalysts by using a wastewater treatment device, wherein the wastewater treatment process includes sequentially performing wastewater pretreatment (flocculation and silicon removal treatment), reverse osmosis treatment (secondary reverse osmosis system) and MVR evaporator treatment, and obtaining recycled water and sludge after treatment, wherein the sludge is filtered by a plate and frame filter. The purpose of the present invention is to achieve the purpose of achieving zero wastewater discharge and comprehensive recycling of recycled water by modifying the pipeline and process of the wastewater treatment device.

[0020] The present invention provides a zero-discharge recycling process for wastewater produced by petroleum cracking catalysts, which specifically comprises: (1) Change the recycled water from sewage treatment from entering the desalination station to entering the production water system and fire water system In the original design, the recycled water was directly sent to the raw water tank of the desalted water station and used as the inlet water for the desalted water. However, in actual operation, due to the small actual water consumption of the desalted water, it is impossible to effectively balance the flow of this recycled water, resulting in a large amount of high-quality water being discharged into the external discharge pool, causing a waste of resources. In addition, the ammonia nitrogen component contained in the recycled water requires the desalted water station to frequently regenerate the cation and cation beds during use, increasing maintenance costs. Finally, since the water supply of the water plant is affected by seasonal changes, especially in dry and rainy weather conditions, the water plant's inventory will be significantly insufficient, resulting in a reduction in water delivery or even a cessation of water supply, which has a serious impact on normal production.

[0021] The present invention changes the recycled water obtained from the sewage treatment device into the production water and fire water system, which has the effect of more effectively utilizing the recycled water resources, reducing the waste of high-quality water, and reducing the maintenance cost of the desalted water station. In addition, by introducing the recycled water into the production water and fire water system, it can also alleviate the water supply pressure of the water plant to a certain extent and improve production stability and reliability.

[0022] (2) Separate the recycled water from the sewage treatment plant according to its quality The recycled water after sewage treatment in the sewage treatment plant consists of two parts, one is the secondary reverse osmosis (RO) produced water from the secondary reverse osmosis system, and the other is the distilled water condensed after MVR evaporation in the MVR evaporator treatment. The conductivity of the secondary reverse osmosis (RO) produced water is low (<10μs / cm), while the conductivity of the distilled water is high and contains ammonia nitrogen. According to the characteristics of these two parts of recycled water, the recycled water process is optimized. Specifically, a new 80 cubic meter distilled water tank is built specifically for storing distilled water, and radar, regulating valves, flow meters and other instrument control measures are added to optimize to ensure stable water quality. Subsequently, the optimized recycled water is sent to the fire water system (molecular sieve, microsphere utility device) for use through pump 1307A. The secondary reverse osmosis (RO) produced water enters the recycled water tank and is pumped to the production water tank through 1307B for subsequent production water use.

[0023] (3) Change the produced water of the sewage treatment plant with desiliconization and dosing reagents to sodium sulfate wastewater after flocculation treatment The original design of the sewage treatment device for silicon removal used sodium carbonate, magnesium agent, and lime solids, which were configured to a concentration of 5% and transported to the dosing position by a screw pump. Through operation in recent years, it was found that the amount of sewage powder agents used was large and the production water was used to configure the agents. For example, to configure 1 ton of sodium carbonate according to 5% carbonate solution, 20 tons of production water were required. The added production water needed to go through the entire sewage treatment process, increasing the treatment cost of the sewage treatment device. Therefore, after analysis and experimental verification, the solvent of sodium carbonate, magnesium agent, and lime solid agents was changed from production water to the supernatant effluent containing sodium sulfate from the second flocculation precipitation gel clarification tank. This optimization not only reduced the amount of production water but also reduced the sewage treatment cost.

[0024] (4) Change the washing water of the plate and frame filter from production water to sewage after sewage pretreatment In the original design of the sewage treatment device, the cloth washing water of the plate and frame filter for gel, molecular sieve and microsphere is production water, and the wastewater after washing will enter the sewage pretreatment system for secondary treatment. In order to further improve production efficiency and reduce sewage treatment costs, a detailed analysis of the turbidity of sewage after gel and microsphere pretreatment was carried out, and a cleaning test was conducted. The test results show that it is completely feasible to use pretreated sewage to clean the filter cloth. Therefore, the cloth washing water of each plate and frame filter in sewage pretreatment is changed to sewage pretreated by each system. In this way, the wastewater after washing can directly enter the respective pretreatment sump for reprocessing, which not only reduces the amount of production water, but also significantly reduces the cost of sewage treatment. This optimization measure not only ensures the smooth progress of production, but also achieves the goals of efficient utilization of resources and environmental protection and energy saving.

[0025] (5) Change the cooling water of 13 pumps in the MVR evaporator unit from production water to recycled water The original design of the MVR evaporator unit of the sewage treatment plant was that the cooling water inlet of the 13 pumps was the production water return water entering the external discharge pool. After operation observation, the production water consumption was large and the external sewage was large. First, the MVR pump cooling water return water was optimized, and the return water was improved in step (2) to the recycling water tank. This optimization can greatly reduce the external sewage discharge volume, but the production water volume of the sewage treatment plant is still large. The water in the recycling water tank is pumped to the 13 pumps of the MVR evaporator unit for cooling water. At the same time, the return water is reintroduced into the recycling water tank to form a complete circulation system. This optimization measure not only greatly reduces the production water consumption of the sewage treatment plant, but also improves the utilization efficiency of water resources.

[0026] (6) Optimize the recycled water delivery pump The control process of the original design of the recycled water delivery pump could not realize the automatic start and stop function, and the operator had to manually start and stop the pump on site according to the liquid level. Each shift, the operator had to go back and forth 8-10 times to start and stop the pump. This repetitive physical labor was not only inefficient, but in view of this, the automatic control process of pump 1 was optimized to achieve start and stop in the manual state of DCS, and to automatically start and stop water delivery based on the liquid level of the recycled water tank, thereby improving work efficiency and reducing the labor burden of operators.

[0027] (7) The replenishment water for the circulating water station is changed from supply water to domestic water.

[0028] The sewage treatment device is equipped with a circulating water station. The original water replenishment design of the circulating water station uses the delivered water for replenishment. However, in subsequent practice, the recycled water is introduced into the delivered water station. Since the recycled water contains ammonia nitrogen components, the water quality analysis results of the circulating water show that the ammonia nitrogen content exceeds the standard. The present invention adjusts the water replenishment method of the circulating water station and directly uses the domestic water provided by the water plant as the production water source, thereby effectively solving the problem of excessive ammonia nitrogen.

[0029] (8) Replace the wastewater treatment plant’s production water system with recycled water In addition to the above-mentioned optimized production water process, the sewage treatment device still uses production water for the configuration of PAM, polyferric sulfate, reducing agent, scale inhibitor, bactericide and other agents. Secondly, pretreatment and MVR circulating cooling water tower also use production water. Finally, chemical cleaning of the membrane system, MVR system cleaning, water foam dust removal and water replenishment are still using production water. Therefore, there is still room for further reduction of production water in the sewage treatment device. Considering that the whole plant is using recycled water and the sewage treatment device itself does not use recycled water, the production water system of the sewage treatment device is optimized based on the use of recycled water as a substitute. First, the production water and recycled water are connected in series with a cross-line at the water inlet of the sewage treatment device corridor. The cross-line pipeline is equipped with a ball valve and a check valve. The water corridor is equipped with an online pressure gauge. The online pressure gauge is electrically connected to the control system. The control system is electrically connected to the ball valve. The water replenishment is opened and closed according to the pressure of the online pressure gauge (the water replenishment valve is closed when the pressure is greater than 0.4Mpa, and the water replenishment is opened when the pressure is less than 0.3Mpa).

[0030] The technical effects achieved by this embodiment in actual production are as follows: Since the process of the present invention was put into operation, the sewage treatment device of the raw material power department has shown a decreasing trend in the use of produced water year by year. From 2021 (March to October), 38,295.73 tons of produced water were used during the 7-month operation period, 36,930.45 tons of produced water were used during the 11-month operation period in 2022 (suspended in February), 8,642.26 tons of produced water were used in the full-year operation in 2023, and 1,071.00 tons of produced water were used during the first three months of 2024.

[0031] As the use of recycled water increases, the water supply of the water plant decreases accordingly, thus achieving effective recycling of water resources. Since the use of recycled water began to be recorded, the water-saving effect has gradually increased. During the 11-month operation in 2022 (stopped in February), 128,400 tons of recycled water were used, 225,200 tons of recycled water were used in the full year of 2023, and 111,400 tons of recycled water were used during the first three months of 2024. After calculation, these water-saving measures have cumulatively increased our efficiency by (128,400+225,200+111,400)×10,000×2.17=1,009,050 yuan.

[0032] Although the present invention has been described in detail with reference to the accompanying drawings and in combination with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, a person of ordinary skill in the art may make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions shall be within the scope of the present invention. Any person of ordinary skill in the art may easily think of changes or substitutions within the technical scope disclosed by the present invention, and these shall be within the scope of protection of the present invention.

Claims

1. A zero-discharge reuse process for wastewater produced by petroleum cracking catalysts, comprising: treating wastewater produced by petroleum cracking catalysts to obtain recycled water and sludge, wherein the sludge is filtered by a plate-and-frame filter, and the wastewater treatment comprises sequentially performing wastewater pretreatment, reverse osmosis treatment, and MVR evaporator treatment, wherein: The recycled water is divided into two parts, one part enters the production water system for reuse, and the other part enters the fire water system for reuse; the sewage pretreatment includes flocculation treatment and silicon removal treatment, and the supernatant after flocculation is reused as the dosing production water in the silicon removal treatment.

2. The zero-discharge reuse process for petroleum cracking catalyst production wastewater according to claim 1, characterized in that: The reverse osmosis treatment adopts a two-stage reverse osmosis system. The recycled water entering the production water system for reuse comes from the secondary reverse osmosis water produced by the secondary reverse osmosis system. The conductivity of the secondary reverse osmosis water produced is <10μs / cm, and the secondary reverse osmosis water is temporarily stored in the recycled water tank.

3. The zero-discharge reuse process for petroleum cracking catalyst production wastewater as claimed in claim 2, characterized in that: The recycled water stored in the recycled water tank is passed into the pump cooling device of the MVR evaporator as cooling water for reuse, and the outlet water of the cooling device is returned to the recycled water tank.

4. The process for zero-discharge reuse of wastewater produced by petroleum cracking catalyst according to claim 1, characterized in that: The recycled water entering the fire water system comes from the distilled water condensed after MVR evaporation in the MVR evaporator.

5. The process for zero-discharge reuse of wastewater produced by petroleum cracking catalyst according to claim 1, characterized in that: The additives used in the desiliconization treatment include sodium carbonate, magnesium and lime.

6. The process for zero-discharge reuse of wastewater produced by petroleum cracking catalyst according to claim 1, characterized in that: A sewage treatment device is used for sewage treatment. The sewage treatment device is provided with a water pipe gallery, and the water inlet of the water pipe gallery is connected to the production water system through a cross-line pipeline.

7. The process for zero-discharge reuse of wastewater produced by petroleum cracking catalyst according to claim 6, characterized in that: The cross-line pipeline is equipped with a ball valve and a check valve, and the water pipe gallery is equipped with a pressure gauge. The pressure gauge is electrically connected to the control system, and the control system is electrically connected to the ball valve.

8. The process for zero-discharge reuse of wastewater produced by petroleum cracking catalyst according to claim 7, characterized in that: The sewage treatment plant is equipped with a circulating water station, and the circulating water station is replenished with domestic water.

9. The process for zero-discharge reuse of wastewater produced by petroleum cracking catalyst according to claim 1, characterized in that: The wastewater generated by wastewater pretreatment is reused as cloth washing water for the plate and frame filter.

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