Oily sludge pyrolysis water treatment method

Abstract

The invention discloses an oily sludge pyrolysis water treatment method, and relates to the technical field of wastewater treatment. The treatment method disclosed by the invention comprises the following steps: S1, treating the oily sludge pyrolysis water to obtain ultrafiltration produced water which does not contain suspended solids and emulsified oil; s2, carrying out catalytic oxidation treatment on the ultrafiltration produced water obtained in the step S1 to obtain oxidized effluent; S3, carrying out evaporation treatment on the oxidized effluent obtained in the step S2 to remove salt so as to obtain desalted effluent; the reaction temperature of catalytic oxidation treatment in the step S2 is 250-280 DEG C, the reaction pressure is 7.0-8.0 MPa, the air speed is 1-2 h <-1 >, the reverse osmosis pressure in the step S4 is larger than or equal to 1.0 MPa, toxic substances and refractory substances can be efficiently removed by controlling the reaction conditions of the catalytic oxidation treatment, and the treatment effect is good. And reverse osmosis treatment is combined for further advanced treatment of pyrolysis water, so that pollution factors such as COD, ammonia nitrogen and salt can be further intercepted, and the quality of produced water can reach emission and even reuse standards.

Description

Technical Field

[0001] The invention relates to the technical field of wastewater treatment, and more specifically to a method for treating oily sludge by pyrolysis water. Background Art

[0002] Oily sludge is mostly a large amount of waste sludge generated during oil extraction and production and processing. This sludge has a complex composition and contains a large amount of aged crude oil, wax, asphaltene, colloid, suspended solids, salts, etc. It also includes a large amount of water treatment agents such as coagulants, corrosion inhibitors, scale inhibitors, and bactericides added during the production process. At present, the common methods for treating oily sludge in China are: pyrolysis, incineration, extraction, thermal washing, etc. The working principle of pyrolysis mainly involves heating organic solid waste to a high temperature in an oxygen-free or low-oxygen environment to decompose it into gas, liquid and solid products. By controlling the reaction conditions such as temperature and oxygen, the pyrolysis furnace allows the organic solid waste to decompose rapidly at high temperature, thereby achieving waste reduction, harmlessness and resource utilization. The combustion chamber of the pyrolysis furnace has a high temperature, complete combustion, a long residence time, and the combustion flue gas emissions are in the dioxin synthesis zone for a very short time, which is less likely to produce dioxins than incineration technology. Pyrolysis produces pyrolysis water. The pyrolysis water of oily sludge generally contains more oil, high COD, high salt content, and some toxic substances. The traditional physical and chemical, biochemical and other treatment processes cannot achieve the required treatment effect. A process technology suitable for treating pyrolysis water of oily sludge is urgently needed.

[0003] The prior art discloses a treatment system and method for pyrolysis water containing oil sludge, and the treatment method comprises the following steps: S1. Oil-water separation: the pyrolysis water containing oil sludge is subjected to oil-water separation treatment; S2. Conditioning and separation: the water phase after the oil-water separation treatment in S1 is subjected to demulsification treatment with a demulsifier, flocculation treatment with a flocculant, and solid-liquid separation treatment to obtain a slag phase and a water phase; S3. Ultrafiltration membrane treatment: the water phase obtained after the above S2 treatment is subjected to ultrafiltration membrane treatment; the concentrated liquid after the S3 ultrafiltration membrane treatment is returned to S2 for conditioning and separation treatment; S4. Nanofiltration membrane treatment : The aqueous phase obtained after the above S3 treatment is treated by nanofiltration membrane; S5. Disc tube reverse osmosis membrane treatment: The aqueous phase obtained after the above S4 treatment is treated by disc tube reverse osmosis membrane; S6. Evaporation and crystallization treatment: The concentrated solution after S4. nanofiltration membrane treatment and the concentrated solution after S5. disc tube reverse osmosis membrane treatment are evaporated and crystallized; The aqueous phases after S4. nanofiltration membrane treatment and S5. disc tube reverse osmosis membrane treatment are returned to S3 ultrafiltration membrane treatment; S7. Pyrolysis treatment: The slag phase after S6 evaporation and crystallization and the slag phase after S2 conditioning and separation are pyrolyzed. This prior art provides a process for treating pyrolysis water containing oil sludge, but the pyrolysis water with COD of 5000-15000 mg / L and ammonia nitrogen value of 100-1000 mg / L still has a COD value of 110-120 after being treated by this process. On the one hand, it is not suitable for treating pyrolysis water containing oil sludge with higher concentration, and on the other hand, the COD removal effect needs to be further improved. Summary of the invention

[0004] The purpose of the present invention is to overcome the defects and shortcomings of the existing treatment methods of oily sludge pyrolysis water, which are unable to treat oily sludge pyrolysis water with higher COD and ammonia nitrogen concentrations and have limited treatment effects, and to provide a method for treating oily sludge pyrolysis water, which treats the pyrolysis water that is difficult to treat through a specific process strip, ultimately achieving the purpose of harmlessness, and can reuse the pyrolysis water in the front-end production to achieve resource utilization.

[0005] The above-mentioned purpose of the present invention is achieved through the following technical solutions:

[0006] A method for treating oily sludge pyrolysis water comprises the following steps:

[0007] S1. Treat the pyrolysis water of oily sludge to obtain ultrafiltration water without suspended matter and emulsified oil;

[0008] S2. Catalytically oxidize the ultrafiltration water obtained in S1 to obtain oxidized water:

[0009] S3. The oxidation effluent of S2 is evaporated to remove salt to obtain desalted effluent;

[0010] S4. The desalinated water from S3 is discharged or reused after reverse osmosis treatment.

[0011] The reaction temperature of the catalytic oxidation treatment in S2 is 250-280°C, the reaction pressure is 7.0-8.0 MPa, and the space velocity is 1-2 h -1 ,

[0012] The reverse osmosis pressure in S4 is ≥1.0MPa.

[0013] Among them, it should be noted that:

[0014] The oily sludge pyrolysis water treatment method of the present invention first undergoes step S1 treatment to obtain ultrafiltration water product free of suspended matter and emulsified oil, thereby ensuring the stability of the water quality of the subsequent process inlet water. The oil content is very low and will not affect the operation of the subsequent wet catalytic oxidation reactor, so the operation stability is very guaranteed.

[0015] The ultrafiltration water enters the wet catalytic oxidation reactor to completely degrade most of the organic matter; the wet catalytic oxidation effluent is evaporated to remove salt, and the water then enters the reverse osmosis system for deep treatment, so that the effluent quality can meet the discharge and reuse standards.

[0016] In the treatment method of the present invention, catalytic oxidation treatment is the main step for degrading the COD of the pyrolysis water of oily sludge. This step can be carried out in a wet catalytic oxidation reactor. The organic matter in the wastewater can be degraded to a great extent in the reactor, and the effluent COD is low, which can keep the crystallized salt of the subsequent MVR relatively clean and is conducive to the recovery of salt components. In order to ensure the realization of the above effects, the present invention needs to control the reaction temperature of the wet catalytic oxidation reactor at 250-280°C, the pressure at 7.0-8.0MPa, and the air velocity at 1-2h -1 .

[0017] The catalyst loaded in the catalytic oxidation treatment reactor of the present invention may be a commonly used catalyst in the art, for example, a transition metal oxide catalyst, for example, metal oxides such as Cu, Mn, and Zn are all effective catalysts.

[0018] Preferably, the catalyst used in the catalytic reactor of the present invention is Al 2 O 3 A carrier on which a CuO catalyst is loaded.

[0019] The overall reaction temperature of the wet catalytic oxidation of the present invention is 250-280°C, and the pressure is 7.0-8.0MPa, which can effectively ensure that the COD removal rate is 95% or above. Too low temperature and pressure will lead to a decrease in the COD removal rate. The wet catalytic oxidation reactor is provided with a heating device, and the temperature is controlled by the heating device.

[0020] The present invention also requires that the reverse osmosis pressure be controlled to be no less than 1.0 MPa. When the reverse osmosis pressure is lower than 1.0 MPa, the removal rates of conductivity, COD and ammonia nitrogen will be significantly reduced, and the overall treatment effect cannot be guaranteed.

[0021] Reverse osmosis treatment is a further in-depth treatment of pyrolysis water. Wide-channel anti-pollution reverse osmosis can be used. In the treatment method of the present invention, it is preferred to control the operating pressure at 1.5-2.0Mpa to further intercept COD, ammonia nitrogen, salt and other pollution factors, and the produced water quality is good, which can meet the discharge or even reuse standards. At the same time, the present invention preferably operates under the above reverse osmosis pressure to achieve the best balance between treatment effect and production capacity.

[0022] The tubular ultrafiltration membrane uses the effluent from the flotation tank as the inlet water, which is mainly used to ensure that the suspended solids and oil content in the effluent are maintained at a very low concentration, thereby ensuring the stable operation of the subsequent wet catalytic oxidation. In a specific embodiment, in order to maintain the treatment effect of the subsequent catalytic oxidation, preferably, the COD value of the ultrafiltration water in S1 is 19000-28000, and the oil content is ≤11%.

[0023] In a specific embodiment, in order to ensure better treatment effects in subsequent steps, preferably, the COD value of the oxidized water in S2 is 900-1600, and the ammonia nitrogen value is 2000-3000 mg / L.

[0024] In a specific embodiment, preferably, the COD value of the desalted water in S3 is 200-500, and the ammonia nitrogen value is 250-400 mg / L.

[0025] In a specific embodiment, preferably, the evaporation treatment in S3 adopts steam mechanical recompression technology MVR evaporation, the evaporation temperature is 80 to 90° C., and the pressure is -80 to -95 KPa.

[0026] Evaporation treatment can be used to separate salt components in wastewater through MVR reactor. The MVR evaporator adopts forced circulation mode. The negative pressure in the system is between -80 and -95 kpa, and the evaporation temperature is between 80 and 90 ° C. This can make the MVR water quality better. The COD value of desalinated water is 200 to 500, and the ammonia nitrogen value is 250 to 400 mg / L. At the same time, the salt components can be recovered by crystallization.

[0027] In another specific embodiment, the ultrafiltration water produced by the present invention that does not contain suspended matter and emulsified oil can be carried out by any conventional method in the art that can achieve this effect. Preferably, in step S1 of the present invention, the pyrolysis water is first allowed to enter the oil separator to remove the floating oil in the water and recover it, and then enter the flotation tank to further remove suspended matter and oil by adding drugs to break the emulsion and flotation. The water effluent from the flotation tank enters the tubular ultrafiltration membrane for further pretreatment, and the ultrafiltration effluent basically does not contain suspended matter and emulsified oil. The three processes of oil separation + flotation + tubular ultrafiltration membrane with oil removal function are complementary and combined. After three pretreatments, the stability of the water quality of the subsequent process inlet is guaranteed, the oil content is very low, and it will not affect the operation of the subsequent wet catalytic oxidation reactor, and the operation stability is very guaranteed.

[0028] In a specific embodiment, preferably, the operating membrane surface flow rate of the ultrafiltration membrane treatment in S1 is 3 to 5 m / s, and the operating pressure is 0.2 to 0.4 MPa.

[0029] In a specific embodiment, preferably, the ultrafiltration membrane treatment in S1 uses an ultrafiltration membrane with a pore size of 30 nm. The tubular ultrafiltration membrane filtration can be made of PVDF material.

[0030] In a specific embodiment, in order to fully recover the floating oil in the pyrolysis water, preferably, the oil separation treatment in S1 adopts a horizontal flow oil separator with a residence time of 1.5 to 2 hours and a horizontal flow rate of the wastewater of 2 to 5 m / s.

[0031] In the flotation treatment, most of the suspended matter and some of the residual oil are removed by adding coagulants, demulsifiers, etc. and then through the flotation effect of fine bubbles in the flotation tank. In a specific embodiment, in order to achieve a better removal effect of suspended matter and floating oil, preferably, the residence time of the dissolved air release zone of the flotation treatment in S1 is 8 to 10 minutes, the residence time of the separation zone is 30 to 40 minutes, the descending flow rate in the separation zone is 1 to 1.2 mm / s, and the dissolved air-water reflux ratio is 30% to 50%.

[0032] In the present invention, the reflux ratio of the flotation machine refers to the water output after the flotation machine has been treated to remove oil and suspended matter, a certain proportion of which returns to the water inlet end of the flotation machine for circulation, and is first pressurized and dissolved in gas by a pressurized gas dissolving tank before returning to the front end, and then released by dissolved gas to generate micron-sized bubbles after returning to the front end of the flotation machine. These bubbles are used to bring the suspended matter and suspended matter in the water to the surface of the page for separation. Without this part of the reflux water, the bubbles required for flotation cannot be generated.

[0033] The oily sludge pyrolysis water treatment method of the present invention is suitable for treating various oily sludge pyrolysis waters, and can be particularly applied to treating oily sludge pyrolysis waters with high COD and high ammonia nitrogen that are difficult to treat, for example, it can be applied to treating oily sludge pyrolysis waters with COD values ​​of 30,000 to 50,000 and ammonia nitrogen values ​​of 2,000 to 3,000 mg / L.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The pretreatment stage of the oily sludge pyrolysis water treatment method of the present invention adopts a complementary combination of three processes with oil removal functions, namely oil separation + flotation + tubular ultrafiltration membrane, to ensure that the oil content of the water in the subsequent stages is very low, and the stability of the subsequent catalytic oxidation reaction is ensured. By controlling the reaction conditions of the catalytic oxidation treatment, toxic substances and difficult-to-degrade substances can be efficiently removed. Combined with reverse osmosis treatment for further deep treatment of the pyrolysis water, COD, ammonia nitrogen, salt and other pollution factors can be further intercepted, and the produced water quality is better.

[0036] The treatment method of the present invention is suitable for treating high COD, high ammonia nitrogen oil-containing sludge pyrolysis water, and has good treatment effect. The effluent COD value is below 100 mg / L, and the ammonia nitrogen value is below 20 mg / L, which can meet the discharge and even reuse standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a process flow chart for the treatment process. DETAILED DESCRIPTION

[0038] The present invention is further described below in conjunction with specific embodiments, but the embodiments do not limit the present invention in any form. Unless otherwise specified, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0039] Example 1

[0040] A method for treating oily sludge by pyrolysis water, the process flow is as follows Figure 1 As shown, the following steps are included:

[0041] S1. First, let the pyrolysis water enter the oil separator to remove the floating oil in the water and recover it.

[0042] Then it enters the flotation tank to further remove suspended matter and oil by adding medicine to break the emulsion and flotation.

[0043] The effluent from the flotation tank enters the tubular ultrafiltration membrane for further pretreatment. The ultrafiltration effluent basically does not contain suspended matter and emulsified oil. After three pretreatments, the stability of the influent water quality of the subsequent processes is guaranteed.

[0044] The grease trap adopts a horizontal flow grease trap, the sewage retention time in the grease trap is 1.5h, and the horizontal flow rate of the wastewater is 3m / s.

[0045] Coagulants and demulsifiers are added to the flotation tank. Most of the suspended solids and some residual oil are removed through the flotation of fine bubbles in the flotation tank. The residence time in the dissolved air release zone of the flotation tank is 9 minutes, the residence time in the separation zone is 35 minutes, the falling flow rate in the separation zone is 1.2 mm / s, and the dissolved air-water reflux ratio is 50%.

[0046] The tubular ultrafiltration membrane uses the effluent from the flotation tank as the inlet water, which is mainly used to ensure that the suspended solids and oil content in the effluent are maintained at a very low concentration, thereby ensuring the stable operation of the subsequent wet catalytic oxidation. The tubular ultrafiltration membrane uses PVDF material and 30nm pore size ultrafiltration membrane, with an operating membrane surface flow rate of 3m / s and an operating pressure of 0.3Mpa;

[0047] S2. The ultrafiltration water obtained in S1 is subjected to catalytic oxidation treatment to obtain oxidized water. The reaction temperature of the wet catalytic oxidation reactor is 270°C, the pressure is 7.5MPa, and the space velocity is 2h -1 :

[0048] S3. The oxidation effluent of S2 is evaporated to remove salt to obtain desalted effluent. The salt components can be recovered by crystallization. The MVR evaporator adopts a forced circulation mode, the negative pressure in the system is -85kpa, and the evaporation temperature is 85℃;

[0049] S4. The desalinated water from S3 is discharged or reused after reverse osmosis treatment. The reverse osmosis system is a deep treatment unit that can further intercept pollution factors such as COD, ammonia nitrogen, and salt. The reverse osmosis unit adopts wide-channel anti-pollution reverse osmosis with an operating pressure of 1.8Mpa.

[0050] The treatment effect of the treatment process of Example 1 on pyrolysis water is shown in Table 1 below:

[0051] Table 1:

[0052]

[0053] Example 2

[0054] A method for treating oily sludge by pyrolysis water, the process flow is as follows Figure 1 As shown, the following steps are included:

[0055] S1. First, let the pyrolysis water enter the oil separator to remove the floating oil in the water and recover it.

[0056] Then it enters the flotation tank to further remove suspended matter and oil by adding medicine to break the emulsion and flotation.

[0057] The effluent from the flotation tank enters the tubular ultrafiltration membrane for further pretreatment. The ultrafiltration effluent basically does not contain suspended matter and emulsified oil. After three pretreatments, the stability of the influent water quality of the subsequent processes is guaranteed.

[0058] The grease trap adopts a horizontal flow grease trap, the sewage retention time in the grease trap is 1.5h, and the horizontal flow rate of the wastewater is 3m / s.

[0059] Coagulants and demulsifiers are added to the flotation tank. Most of the suspended solids and some residual oil are removed through the flotation of fine bubbles in the flotation tank. The residence time in the dissolved air release zone of the flotation tank is 9 minutes, the residence time in the separation zone is 35 minutes, the falling flow rate in the separation zone is 1.2 mm / s, and the dissolved air-water reflux ratio is 50%.

[0060] The tubular ultrafiltration membrane uses the effluent from the flotation tank as the inlet water, which is mainly used to ensure that the suspended solids and oil content in the effluent are maintained at a very low concentration, thereby ensuring the stable operation of the subsequent wet catalytic oxidation. The tubular ultrafiltration membrane uses PVDF material and 30nm pore size ultrafiltration membrane, with an operating membrane surface flow rate of 3m / s and an operating pressure of 0.3Mpa;

[0061] S2. The ultrafiltration water obtained in S1 is subjected to catalytic oxidation treatment to obtain oxidized water. The reaction temperature of the wet catalytic oxidation reactor is 268°C, the pressure is 8.0 MPa, and the space velocity is 1.8 h -1 :

[0062] S3. The oxidation effluent of S2 is evaporated to remove salt to obtain desalted effluent. The salt components can be recovered by crystallization. The MVR evaporator adopts a forced circulation mode, the negative pressure in the system is -88kpa, and the evaporation temperature is 83℃;

[0063] S4. The desalinated water from S3 is discharged or reused after reverse osmosis treatment. The reverse osmosis system is a deep treatment unit that can further intercept pollution factors such as COD, ammonia nitrogen, and salt. The reverse osmosis unit adopts wide-channel anti-pollution reverse osmosis with an operating pressure of 2.0Mpa.

[0064] The treatment effect of the treatment process of Example 2 on pyrolysis water is shown in Table 2 below:

[0065] Table 2:

[0066]

[0067] Example 3

[0068] A method for treating oily sludge by pyrolysis water, the process flow is as follows Figure 1 As shown, the following steps are included:

[0069] S1. First, let the pyrolysis water enter the oil separator to remove the floating oil in the water and recover it.

[0070] Then it enters the flotation tank to further remove suspended matter and oil by adding medicine to break the emulsion and flotation.

[0071] The effluent from the flotation tank enters the tubular ultrafiltration membrane for further pretreatment. The ultrafiltration effluent basically does not contain suspended matter and emulsified oil. After three pretreatments, the stability of the influent water quality of the subsequent processes is guaranteed.

[0072] The grease trap adopts a horizontal flow grease trap, the sewage retention time in the grease trap is 1.5h, and the horizontal flow rate of the wastewater is 3m / s.

[0073] Coagulants and demulsifiers are added to the flotation tank. Most of the suspended solids and some residual oil are removed through the flotation of fine bubbles in the flotation tank. The residence time in the dissolved air release zone of the flotation tank is 9 minutes, the residence time in the separation zone is 35 minutes, the falling flow rate in the separation zone is 1.2 mm / s, and the dissolved air-water reflux ratio is 50%.

[0074] The tubular ultrafiltration membrane uses the effluent from the flotation tank as the inlet water, which is mainly used to ensure that the suspended solids and oil content in the effluent are maintained at a very low concentration, thereby ensuring the stable operation of the subsequent wet catalytic oxidation. The tubular ultrafiltration membrane uses PVDF material and 30nm pore size ultrafiltration membrane, with an operating membrane surface flow rate of 3m / s and an operating pressure of 0.3Mpa;

[0075] S2. The ultrafiltration water obtained in S1 is subjected to catalytic oxidation treatment to obtain oxidized water. The reaction temperature of the wet catalytic oxidation reactor is 277°C, the pressure is 7.8MPa, and the space velocity is 1.6h -1 :

[0076] S3. The oxidation effluent of S2 is evaporated to remove salt to obtain desalted effluent. The salt components can be recovered by crystallization. The MVR evaporator adopts a forced circulation mode, the negative pressure in the system is -90kpa, and the evaporation temperature is 89℃;

[0077] S4. The desalinated water from S3 is discharged or reused after reverse osmosis treatment. The reverse osmosis system is a deep treatment unit that can further intercept pollution factors such as COD, ammonia nitrogen, and salt. The reverse osmosis unit adopts wide-channel anti-pollution reverse osmosis with an operating pressure of 1.6Mpa.

[0078] The treatment effect of the treatment process of Example 3 on pyrolysis water is shown in Table 3 below:

[0079] Table 3:

[0080]

[0081] Comparative Example 1

[0082] A method for treating oily sludge pyrolysis water comprises the following steps:

[0083] S1. First, let the pyrolysis water enter the oil separator to remove the floating oil in the water and recover it.

[0084] Then it enters the flotation tank to further remove suspended matter and oil by adding medicine to break the emulsion and flotation.

[0085] The effluent from the flotation tank enters the tubular ultrafiltration membrane for further pretreatment. The ultrafiltration effluent basically does not contain suspended matter and emulsified oil. After three pretreatments, the stability of the influent water quality of the subsequent processes is guaranteed.

[0086] The grease trap adopts a horizontal flow grease trap, the sewage retention time in the grease trap is 1.5h, and the horizontal flow rate of the wastewater is 3m / s.

[0087] Coagulants and demulsifiers are added to the flotation tank. Most of the suspended solids and some residual oil are removed through the flotation of fine bubbles in the flotation tank. The residence time in the dissolved air release zone of the flotation tank is 9 minutes, the residence time in the separation zone is 35 minutes, the falling flow rate in the separation zone is 1.2 mm / s, and the dissolved air-water reflux ratio is 50%.

[0088] The tubular ultrafiltration membrane uses the effluent from the flotation tank as the inlet water, which is mainly used to ensure that the suspended solids and oil content in the effluent are maintained at a very low concentration, thereby ensuring the stable operation of the subsequent wet catalytic oxidation. The tubular ultrafiltration membrane uses PVDF material and 30nm pore size ultrafiltration membrane, with an operating membrane surface flow rate of 3m / s and an operating pressure of 0.3Mpa;

[0089] S2. The ultrafiltration water obtained in S1 is subjected to catalytic oxidation treatment to obtain oxidized water. The reaction temperature of the wet catalytic oxidation reactor is 185°C, the pressure is 3.0 MPa, and the space velocity is 3.5 h -1 :

[0090] S3. The oxidation effluent of S2 is evaporated to remove salt to obtain desalted effluent. The salt components can be recovered by crystallization. The MVR evaporator adopts a forced circulation mode, the negative pressure in the system is -65kpa, and the evaporation temperature is 97℃;

[0091] S4. The desalinated water from S3 is discharged or reused after reverse osmosis treatment. The reverse osmosis system is a deep treatment unit that can further intercept pollution factors such as COD, ammonia nitrogen, and salt. The reverse osmosis unit adopts wide-channel anti-pollution reverse osmosis with an operating pressure of 0.5Mpa.

[0092] The operating data are shown in Table 4.

[0093]

[0094] The above effluent quality cannot meet the standards for taking over and reuse.

[0095] Comparative Example 2

[0096] A method for treating oily sludge pyrolysis water comprises the following steps:

[0097] S1. First, let the pyrolysis water enter the oil separator to remove the floating oil in the water and recover it.

[0098] Then it enters the flotation tank to further remove suspended matter and oil by adding medicine to break the emulsion and flotation.

[0099] The effluent from the flotation tank enters the tubular ultrafiltration membrane for further pretreatment. The ultrafiltration effluent basically does not contain suspended matter and emulsified oil. After three pretreatments, the stability of the influent water quality of the subsequent processes is guaranteed.

[0100] The grease trap adopts a horizontal flow grease trap, the sewage retention time in the grease trap is 1.5h, and the horizontal flow rate of the wastewater is 3m / s.

[0101] Coagulants and demulsifiers are added to the flotation tank. Most of the suspended solids and some residual oil are removed through the flotation of fine bubbles in the flotation tank. The residence time in the dissolved air release zone of the flotation tank is 9 minutes, the residence time in the separation zone is 35 minutes, the falling flow rate in the separation zone is 1.2 mm / s, and the dissolved air-water reflux ratio is 50%.

[0102] The tubular ultrafiltration membrane uses the effluent from the flotation tank as the inlet water, which is mainly used to ensure that the suspended solids and oil content in the effluent are maintained at a very low concentration, thereby ensuring the stable operation of the subsequent wet catalytic oxidation. The tubular ultrafiltration membrane uses PVDF material and 30nm pore size ultrafiltration membrane, with an operating membrane surface flow rate of 3m / s and an operating pressure of 0.3Mpa;

[0103] S2. The ultrafiltration water obtained in S1 is subjected to catalytic oxidation treatment to obtain oxidized water. The reaction temperature of the wet catalytic oxidation reactor is 215°C, the pressure is 4.5MPa, and the space velocity is 2.8h -1 :

[0104] S3. The oxidation effluent of S2 is evaporated to remove salt to obtain desalted effluent. The salt components can be recovered by crystallization. The MVR evaporator adopts a forced circulation mode, the negative pressure in the system is -70kpa, and the evaporation temperature is 95℃;

[0105] S4. The desalinated water from S3 is discharged or reused after reverse osmosis treatment. The reverse osmosis system is a deep treatment unit that can further intercept pollution factors such as COD, ammonia nitrogen, and salt. The reverse osmosis unit adopts wide-channel anti-pollution reverse osmosis with an operating pressure of 0.4Mpa.

[0106] The operating data is shown in Table 5.

[0107] Table 5.

[0108]

[0109] The above effluent quality cannot meet the standards for taking over and reuse.

[0110] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for treating oily sludge by pyrolysis water, characterized in that: The steps include: S1. Treat the pyrolysis water of oily sludge to obtain ultrafiltration water without suspended matter and emulsified oil; S2. Catalytically oxidize the ultrafiltration water obtained in S1 to obtain oxidized water: S3. The oxidation effluent of S2 is evaporated to remove salt to obtain desalted effluent; S4. The desalinated water from S3 is discharged or reused after reverse osmosis treatment. The reaction temperature of the catalytic oxidation treatment in S2 is 250-280°C, the reaction pressure is 7.0-8.0 MPa, and the space velocity is 1-2 h -1 , The reverse osmosis pressure in S4 is ≥1.0MPa.

2. The method for treating oily sludge by pyrolysis water according to claim 1, characterized in that: The reverse osmosis pressure in S4 is 1.5-2.0 MPa.

3. The method for treating oily sludge by pyrolysis water according to claim 1, characterized in that: The COD value of the ultrafiltration water produced in S1 is 19000-28000, and the oil content is ≤11%.

4. The method for treating oily sludge by pyrolysis water according to claim 1, characterized in that: The COD value of the oxidized water in S2 is 900-1600, and the ammonia nitrogen value is 2000-3000 mg / L.

5. The method for treating oily sludge by pyrolysis water according to claim 1, characterized in that: The COD value of the desalted water in S3 is 200-500, and the ammonia nitrogen value is 250-400 mg / L.

6. The method for treating oily sludge by pyrolysis water according to claim 1, characterized in that: The evaporation process in S3 adopts steam mechanical recompression technology for evaporation, with an evaporation temperature of 80 to 90°C and a pressure of -80 to -95KPa.

7. The method for treating oily sludge by pyrolysis water according to claim 1, characterized in that: In S1, the floating oil in the pyrolysis water of the oily sludge is separated by oil separation treatment, and then the suspended matter and oil are removed by demulsification and flotation treatment. The effluent is further treated with an ultrafiltration membrane to obtain ultrafiltration water.

8. The method for treating oily sludge by pyrolysis water according to claim 7, characterized in that: The operating membrane surface flow rate of the ultrafiltration membrane treatment in S1 is 3 to 5 m / s, and the operating pressure is 0.2 to 0.4 MPa.

9. The method for treating oily sludge by pyrolysis water according to claim 7, characterized in that: The residence time of dissolved gas release zone in S1 flotation treatment is 8-10 min, the residence time of separation zone is 30-40 min, the descending velocity of separation zone is 1-1.2 mm / s, and the dissolved gas-water reflux ratio is 30%-50%.

10. The method for treating oily sludge by pyrolysis water according to any one of claims 1 to 9, characterized in that: The COD value of the oily sludge pyrolysis water is 30,000 to 50,000, and the ammonia nitrogen value is 2,000 to 3,000 mg / L.

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