A device and process for treating acid-containing wastewater from an acidulated oil production process

Abstract

The application discloses an acid-containing wastewater treatment device and process for acidified oil production process, and belongs to the field of wastewater treatment. The device comprises a wastewater vaporization system, a gas-phase deacidification system, a gas-phase catalytic oxidation system and a cooling and discharging system, and is composed of a heating kettle, a wastewater circulating pump and a graphite reboiler to form a corrosion-resistant wastewater vaporization system, so that organic light components and water in the acid-containing wastewater in the acidified oil production process are efficiently separated. The alkali liquor is used for gas-phase deacidification of the organic light component-containing acid wastewater vapor to effectively prevent corrosion of subsequent equipment. The device adopts a two-stage waste heat recovery mode to utilize high-temperature steam to preheat and vaporize the organic light component-containing wastewater steam and the acid-containing wastewater in the acidified oil production process, so that the energy consumption is effectively reduced, and the obtained steam condensate water reaches the first-level standard of comprehensive discharge. In addition, the acid-containing concentrated liquid generated by the wastewater vaporization system is used for acidification to prepare acidified oil. The device has the advantages of high separation efficiency, low operation cost, energy saving and environmental protection and the like.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to an apparatus and process for treating acidic wastewater from the production of acidified oil. Background Technology

[0002] Acidified oil, a key raw material in the industrial production of fatty acids, oleic acid, and biodiesel, is primarily obtained through the acidification of soapstock. However, the production of acidified oil generates a large amount of highly acidic wastewater characterized by high salt content, high chemical oxygen demand (COD), high phosphorus content, high ammonia nitrogen content, high color, and poor biodegradability. It has been reported that producing one ton of finished acidified oil generates two tons of acidic wastewater. Treating this wastewater is extremely difficult, and conventional wastewater treatment methods are insufficient to meet national discharge standards. Therefore, the effective treatment of acidic wastewater from acidified oil production has become an essential requirement for sustainable development.

[0003] Chinese invention patent CN 221692952 U proposes an acidified oil wastewater treatment device, which removes suspended solids from acidified oil wastewater by setting a fixed column, buffer block, oil filter box, oil filter hole, reset spring and extension rod in the treatment box.

[0004] Chinese invention patent CN 214192687 U proposes a wastewater treatment device for the production of acidified oil, which achieves full neutralization and deacidification of the wastewater generated from the production of acidified oil in the treatment tank through a lime milk dosing module with controllable quality.

[0005] Chinese invention patent CN 218403828 U proposes a device for removing high-concentration sulfate from acidified oil wastewater. By setting an overflow buffer plate inside the shell, the inner cavity of the shell is divided into a preliminary neutralization reaction chamber and a deep neutralization reaction chamber. The acidified oil wastewater fully contacts and reacts with the neutralizing agent and undergoes precipitation and separation to achieve the removal of high-concentration sulfate.

[0006] The aforementioned patents have all achieved the treatment of a single discharge index of acidic wastewater from the acidified oil production process, but they have not yet achieved the efficient treatment of multiple discharge indexes together. Furthermore, the method of directly adding alkaline reagents to the wastewater to neutralize and remove acid consumes a large amount of reagents. Summary of the Invention

[0007] To address the aforementioned technical problems in the existing technology, the present invention provides an apparatus for treating acidic wastewater from the acidification oil production process.

[0008] The technical solution adopted in this invention is as follows:

[0009] An apparatus for treating acidic wastewater from an acidified oil production process, comprising:

[0010] The wastewater vaporization system includes a heating kettle, a wastewater circulation pump, and a graphite reboiler connected by a closed-loop pipeline. Acidic wastewater from the acidification oil production process at the bottom of the heating kettle is pumped out by the wastewater circulation pump, heated and vaporized through the cold channel of the graphite reboiler, and then sent to the top of the heating kettle. Acidic wastewater vapor containing light organic components discharged from the gas outlet at the top of the heating kettle is sent to the gas phase deacidification system.

[0011] The gas phase deacidification system uses alkaline solution to absorb and treat acidic wastewater vapor containing light organic components. After deacidification, the wastewater vapor containing light organic components is sent to the gas phase catalytic oxidation system.

[0012] The gas-phase catalytic oxidation system includes an MVR Roots compressor, a heat recovery heat exchanger, an electromagnetic heater, and a fixed-bed catalytic oxidation tower. Wastewater vapor containing light organic components after deacidification is compressed and pumped out by the MVR Roots compressor. The outlet of the MVR Roots compressor is connected by pipelines through the cold channel of the heat recovery heat exchanger, the electromagnetic heater, the fixed-bed catalytic oxidation tower, and the hot channel of the heat recovery heat exchanger. Air is also introduced into the inlet pipeline of the electromagnetic heater.

[0013] Steam from the outlet of the heat recovery heat exchanger flows through the heat channel of the graphite reboiler, and steam and steam condensate discharged from the heat channel of the graphite reboiler enter the cooling discharge system.

[0014] Furthermore, the heating vessel is equipped with a jacket for introducing a heat source, and the jacket is equipped with a steam inlet and a steam outlet; the wastewater circulation pump outlet pipeline is equipped with an acid-containing concentrate outlet.

[0015] Furthermore, the gas phase deacidification system includes a deacidification tower, an alkali tank, and an alkali circulation pump. The deacidification tower is filled with packing material, and the air inlet at the bottom of the deacidification tower is connected to the air outlet at the top of the heating vessel.

[0016] The alkali solution in the alkali tank is transported to the top of the deacidification tower by the alkali solution circulation pump to deacidify the rising acidic wastewater vapor containing light organic components. After deacidification, the alkali solution is returned to the alkali tank to form a cycle.

[0017] Furthermore, the cooling exhaust system includes a water storage tank, a condenser, and a Roots blower connected in sequence by pipelines. After steam and steam condensate enter the cooling exhaust system, the steam condensate is discharged into the water storage tank, and the uncondensed steam passes through the water storage tank and enters the condenser for condensation. The resulting condensate is discharged into the water storage tank, and the remaining non-condensable air is drawn out and discharged by the Roots blower.

[0018] A process for treating acidic wastewater from the production of acidified oil includes the following steps:

[0019] 1) Acidic wastewater from the acidification oil production process enters the wastewater vaporization system. It is separated by heating and vaporization in a heating kettle and heating and vaporization in a graphite reboiler to form acidic wastewater vapor containing light organic components, which then enters the gas phase deacidification system. The acidic concentrate obtained by vaporization and concentration is discharged through the acidic concentrate outlet on the side line of the wastewater circulation pump outlet pipeline and reused in the subsequent acidification process to prepare acidified oil.

[0020] 2) In the gas phase deacidification system, alkaline solution is used to spray and absorb the acidic wastewater vapor containing organic light components from step 1) in a deacidification tower equipped with packing. The wastewater vapor containing organic light components after gas phase deacidification enters the gas phase catalytic oxidation system.

[0021] 3) Wastewater vapor containing light organic components entering the gas phase catalytic oxidation system is compressed and pumped to the cold channel of the heat recovery heat exchanger by the MVR Roots compressor. After being heated by heat exchange, it is mixed with the introduced air and heated by the electromagnetic heater. Then it enters the fixed bed catalytic oxidation tower for catalytic oxidation reaction. The resulting high-temperature steam first enters the hot channel of the heat recovery heat exchanger and is cooled by heat exchange. Then it is used as the heat source of the graphite reboiler and cooled by heat exchange before entering the cooling and discharge system.

[0022] 4) The steam entering the cooling and exhaust system is condensed, and the resulting condensate is stored, while the remaining non-condensable air is vented.

[0023] Furthermore, the absolute pressure inside the heating vessel and graphite reboiler is 70-100 kPa.

[0024] Furthermore, in step 3), the temperature of the wastewater vapor containing light organic components at the outlet of the MVR Roots compressor is 90-120 ℃, the temperature after heat exchange and heating in the cold channel of the heat recovery heat exchanger is 200-250 ℃, and the heating temperature of the electromagnetic heater is 250-300 ℃.

[0025] Further, in step 3), the reaction temperature inside the fixed-bed catalytic oxidation tower is 250-300 ℃, and the catalyst filled inside is an iron-based catalyst or a combination of an iron-based catalyst and a platinum-based catalyst. The iron-based catalyst uses red mud as a support and Fe2O3 as the active component, with a Fe2O3 loading of 35-40%. The platinum-based catalyst uses cordierite as a support and Pt as the active component, with a loading of 0.05-0.2%.

[0026] Furthermore, the catalyst filled inside the fixed-bed catalytic oxidation tower is a combination of iron-based catalyst and platinum-based catalyst. The iron-based catalyst and platinum-based catalyst have the same particle size range, and the volume ratio of iron-based catalyst to platinum-based catalyst is 1:0.5-2, preferably 1:0.8-1.2.

[0027] Furthermore, in step 3), the temperature of the steam after heat exchange and cooling through the heat recovery heat exchanger is 110-150℃.

[0028] The beneficial effects of this invention are as follows:

[0029] 1. A corrosion-resistant wastewater vaporization system consisting of a heated kettle and a graphite reboiler is used to efficiently separate organic light components and water from acidic wastewater in the acidification oil production process. The concentrated acidic liquid obtained through vaporization is reused in the acidification process to prepare acidified oil. The graphite reboiler is designed to achieve the required wastewater evaporation rate, recover the latent heat in the steam, and facilitate the production of the concentrated acidic liquid.

[0030] 2. A gas-phase deacidification system consisting of a deacidification tower, an alkali tank, and an alkali circulation pump is used to perform gas-phase deacidification on acidic wastewater vapor containing organic light components, which effectively prevents corrosion of subsequent equipment, reduces equipment costs, ensures stable operation, and significantly reduces the consumption of alkaline reagents.

[0031] 3. Low-temperature catalytic oxidation technology is adopted to effectively reduce the chemical oxygen demand (COD), phosphorus content and ammonia nitrogen content of acidic wastewater in the acidification oil production process. The low-temperature reaction conditions and iron-based catalysts significantly reduce treatment costs.

[0032] 4. A two-stage waste heat recovery method is adopted to recover the high-temperature steam waste heat generated by catalytic oxidation, which is used to preheat the steam containing organic light components and the acidic wastewater in the gasification and acidification process, effectively reducing energy consumption. The steam condensate obtained is reused, which significantly reduces the amount of fresh water used.

[0033] 5. By using a combination of iron-based and platinum-based catalysts, the COD, phosphorus, and ammonia nitrogen content of the mixed wastewater consisting of acidic wastewater and biogas slurry in the acidified oil production process can be effectively reduced. Attached Figure Description

[0034] Figure 1 This is a diagram of the acid wastewater treatment device for the acidified oil production process of the present invention;

[0035] Figure 1 In the middle: 1-Roots induced draft fan, 2-Condenser, 3-Water storage tank, 4-Graphite reboiler, 5-Wastewater circulation pump, 6-Deacidification tower, 7-Alkali tank, 8-Alkali circulation pump, 9-Heating kettle, 10-MVR Roots compressor, 11-Fixed bed catalytic oxidation tower, 12-Heat recovery heat exchanger, 13-Electromagnetic heater; a-Condensate outlet, b-Condensate inlet, c-Recovered condensate outlet, d-Acid concentrate outlet, e-Wastewater inlet, f-Steam inlet, g-Steam outlet, h-Air inlet. Detailed Implementation

[0036] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0037] Example: Control Figure 1

[0038] A device for treating acidic wastewater from an acidification oil production process includes a Roots blower 1, a condenser 2, a water storage tank 3, a graphite reboiler 4, a wastewater circulation pump 5, a deacidification tower 6, an alkali tank 7, an alkali circulation pump 8, a heating kettle 9, an MVR Roots compressor 10, a fixed-bed catalytic oxidation tower 11, a heat recovery heat exchanger 12, and an electromagnetic heater 13; condensate outlet a, condensate inlet b, recovered condensate outlet c, acidic concentrate outlet d, wastewater inlet e, steam inlet f, steam outlet g, and air inlet h.

[0039] Heating kettle 9, wastewater circulation pump 5, and graphite reboiler 4 are connected in a closed loop via pipelines to form a wastewater vaporization system. Acidic wastewater from the acidification oil production process in the bottom of heating kettle 9 is pumped out by wastewater circulation pump 5, heated and vaporized through the cold channel of graphite reboiler 4, and then sent to the top of heating kettle 9. Acidic wastewater vapor containing light organic components discharged from the top outlet of heating kettle 9 is sent to the bottom of deacidification tower 6 of the gas phase deacidification system.

[0040] The heating vessel 9 is equipped with a jacket for introducing a heat source, and the jacket has a steam inlet f and a steam outlet g; the wastewater circulation pump 5 has an acid-containing concentrate outlet d on its outlet pipe. The upper part of the heating vessel 9 has a wastewater inlet e.

[0041] The deacidification tower 6, alkali tank 7, and alkali circulation pump 8 are connected by pipelines to form a loop, constituting a gas-phase deacidification system. The deacidification tower 6 is filled with packing material, and the air inlet at the bottom of the deacidification tower 6 is connected to the air outlet at the top of the heating vessel 9. The alkali solution in the alkali tank 7 is transported to the top of the deacidification tower 6 by the alkali circulation pump 8 to deacidify the rising acidic wastewater vapor containing organic light components. After deacidification, the alkali solution is returned to the alkali tank 7, forming an alkali circulation loop.

[0042] The MVR Roots compressor 10, heat recovery heat exchanger 12, electromagnetic heater 13, and fixed-bed catalytic oxidation tower 11 are connected by pipelines to form a gas-phase catalytic oxidation system. Wastewater vapor containing light organic components discharged from the top of the deacidification tower 6 is compressed and pumped by the MVR Roots compressor 10. The outlet of the MVR Roots compressor 10 is connected by pipelines sequentially through the cold channel of the heat recovery heat exchanger 12, the electromagnetic heater 13, the fixed-bed catalytic oxidation tower 11, and the hot channel of the heat recovery heat exchanger 12. An air inlet h is also provided on the inlet pipe of the electromagnetic heater 13 for introducing air.

[0043] Steam from the hot channel outlet of heat recovery heat exchanger 12 flows through the hot channel of graphite reboiler 4 to heat the acidic wastewater from the acidification oil production process flowing through the cold channel of graphite reboiler 4. Steam and steam condensate discharged from the hot channel of graphite reboiler 4 enter the cooling discharge system.

[0044] The water storage tank 3, condenser 2, and Roots induced draft fan 1 are connected by pipelines to form a cooling and exhaust system. Steam and steam condensate enter the cooling and exhaust system; the steam condensate is discharged into the water storage tank 3, while uncondensed steam passes through the water storage tank 3 and enters the condenser 2 for condensation. The resulting condensate is discharged into the water storage tank 3, and the remaining non-condensable air is drawn out and discharged by the Roots induced draft fan 1. The condenser 2 adopts a heat exchanger structure, which has a condensate outlet a and a condensate inlet b.

[0045] The wastewater vaporization system, gas phase deacidification system, gas phase catalytic oxidation system, and cooling discharge system are connected by pipelines.

[0046] When the device of the present invention is running, the process flow is as follows:

[0047] Acidic wastewater from the acidification oil production process enters the heating vessel 9 of the wastewater vaporization system through wastewater inlet e. Heated by both the heating vessel 9 (with an internal absolute pressure of 70-100 kPa) and the graphite reboiler 4, it vaporizes and separates into acidic wastewater vapor containing light organic components, which then enters the gas-phase deacidification system. In the gas-phase deacidification system, the alkali solution in the alkali tank 7 is pumped by the alkali circulation pump 8 to the deacidification tower 6 filled with ceramic packing. The alkali solution is evenly distributed by the liquid distributor at the top of the deacidification tower 6, performing gas-phase deacidification on the acidic wastewater vapor containing light organic components. After deacidification, the alkali solution flows back into the alkali tank 7 for recycling. The deacidified wastewater vapor containing light organic components then enters the gas-phase catalytic oxidation system. The MVR Roots compressor 10 provides power to heat the wastewater vapor containing light organic components through the cold channel of the heat recovery heat exchanger 12, then preheats it in the electromagnetic heater 13 at 250-300 ℃, and finally enters the fixed-bed catalytic oxidation tower 11 containing the catalyst at 250-300 ℃. The catalytic oxidation reaction is carried out at ℃, and the high-temperature steam obtained is cooled by heat exchange through the hot channel of the heat recovery heat exchanger 12. The discharged steam enters the hot channel of the graphite reboiler 4 in the wastewater vaporization system, heating and vaporizing the wastewater in the cold channel of the graphite reboiler 4. The concentrated acidic wastewater is discharged through the acidic concentrate outlet d. The steam and steam condensate discharged from the hot channel of the graphite reboiler 4 enter the cooling discharge system. The steam condensate is discharged into the water storage tank 3, and the steam enters the condenser 2 through the water storage tank 3 for condensation. The resulting condensate is discharged into the water storage tank 3, and the remaining non-condensable air is drawn out and discharged by the Roots induced draft fan 1.

[0048] Example 1: According to as follows Figure 1 The apparatus shown is used for the treatment of acidic wastewater from the acidification oil production process.

[0049] Acidic wastewater containing organic light components (parameters shown in Table 1) from the production process of acidified oil with a salt content of 15 wt% is vaporized and separated under the combined heating action of a heating kettle 9 with an absolute pressure of 70 kPa and a graphite reboiler 4. The resulting 90°C acidic wastewater vapor containing organic light components (parameters shown in Table 2) enters the deacidification tower 6 for gas-phase deacidification. The alkaline solution used for gas-phase deacidification is a 1 wt% NaOH aqueous solution. The alkaline solution parameters after 1 hour of gas-phase deacidification are shown in Table 3. The wastewater vapor containing organic light components after gas-phase deacidification (parameters shown in Table 4) is powered by an MVR Roots compressor 10 and passes through the cold channel of a heat recovery heat exchanger 12. It is then mixed with 4% of the volume of air containing organic light components in the air and enters an electromagnetic heater 13 for preheating to 270°C. It then enters a fixed-bed catalytic oxidation tower 11 containing an iron-based catalyst with Fe2O3 as the active component (the support is red mud, the Fe2O3 loading is 37.77 wt%, and the catalyst particle size range is 5-8 mesh). The oxidation process is carried out at a rate of 4000 h. -1 Volumetric hourly space velocity (VHSV) passes through the catalyst bed for catalytic oxidation at 270 °C. The resulting 270 °C high-temperature steam is then passed through the hot channel of heat recovery heat exchanger 12 for heat exchange. This preheats the 100 °C (100 kPa MVR Roots compressor outlet absolute pressure raises the temperature of the organic light component wastewater steam to 100 °C) in the cold channel of heat recovery heat exchanger 12 to 240 °C. The 130 °C steam exiting the hot channel of heat recovery heat exchanger 12 enters the hot channel of graphite reboiler 4 in the wastewater vaporization system, vaporizing the acidic wastewater from the acidification oil production process in the cold channel of graphite reboiler 4 into 90 °C organic light component wastewater steam. Acidic concentrate is continuously collected from the side line of the outlet pipeline of wastewater circulation pump 5 (parameters are shown in Table 5). Steam and steam condensate (parameters shown in Table 6) discharged from the hot channel of graphite reboiler 4 enter water storage tank 3. Steam enters condenser 2 through water storage tank 3 for condensation, and the resulting condensate is discharged into water storage tank 3. The remaining non-condensable air is drawn out and discharged by Roots induced draft fan 1.

[0050] After treatment, the chemical oxygen demand (COD) of the acidic wastewater from the acidification oil production process can be reduced from the initial 68250 mg / L to below 50 mg / L, with a removal rate of over 99.9%, meeting the first-class standard for integrated industrial wastewater discharge; the phosphorus content of the acidic wastewater from the acidification oil production process can be reduced from the initial 6850 mg / L to below 0.1 mg / L, with a removal rate of over 99.9%, meeting the first-class standard for integrated industrial wastewater discharge; and the ammonia nitrogen content of the acidic wastewater from the acidification oil production process can be reduced from the initial 1266 mg / L to below 15 mg / L, with a removal rate of over 98.8%, meeting the first-class standard for integrated industrial wastewater discharge.

[0051] The high-temperature steam condensate obtained during the treatment process can be reused, significantly reducing the amount of fresh water used. The acid-containing concentrate obtained during the treatment process can be reused in the acidification process to prepare acidified oil. The alkaline solution that has been circulated for a long time during the treatment process can be treated using the device of this invention when the gas phase deacidification system is stopped, and can be treated according to the method described in Example 2.

[0052] Table 1. Parameters of acidic wastewater from the acidified oil production process

[0053] .

[0054] Table 2. Steam parameters of acidic wastewater containing light organic components

[0055] .

[0056] Table 3. Parameters of alkaline solution after gas-phase deacidification

[0057] .

[0058] Table 4. Vapor parameters of wastewater containing light organic components after gas-phase deacidification

[0059] .

[0060] Table 5. Parameters of Acid-Containing Concentrate

[0061] .

[0062] Table 6. Parameters of steam condensate after catalytic oxidation

[0063] .

[0064] Example 2: According to as follows Figure 1 The apparatus shown is used for treating mixed wastewater containing acid and biogas slurry from the acidification oil production process. Its operation steps are the same as in Example 1, except for the following two points:

[0065] 1. The acidic wastewater from the acidification oil production process entering through the wastewater inlet e of the heating kettle 9 is replaced with a mixed wastewater consisting of 20 wt% acidic wastewater from the acidification oil production process and 80 wt% biogas slurry;

[0066] 2. The gas phase deacidification system is stopped, and the remaining operating steps are the same as in Example 1.

[0067] By mixing acidic wastewater from the acidification oil production process with biogas slurry, the hydrogen ions in the acidic wastewater can remove soap from the biogas slurry, thus avoiding foam entrainment during wastewater vaporization.

[0068] The parameters of the mixed wastewater are shown in Table 7. The parameters of the wastewater vapor containing light components formed by the vaporization of the mixed wastewater are shown in Table 8. The parameters of the acid-containing concentrate of the mixed wastewater collected from the side of the outlet pipeline of wastewater circulation pump 5 are shown in Table 9 (the sulfuric acid in the acid wastewater cannot evaporate, so the pH of the concentrate decreases). The parameters of the steam condensate after the catalytic oxidation of the mixed wastewater containing light components are shown in Table 10.

[0069] After treatment, the chemical oxygen demand (COD) of the mixed wastewater decreased from the initial 20410 mg / L to below 50 mg / L, with a removal rate exceeding 99.9%, meeting the Class I standard for integrated industrial wastewater discharge. The phosphorus content of the mixed wastewater decreased from the initial 1256 mg / L to below 0.1 mg / L, with a removal rate exceeding 99.9%, also meeting the Class I standard for integrated industrial wastewater discharge. The ammonia nitrogen content of the mixed wastewater decreased from the initial 8298 mg / L to 1244 mg / L, with a removal rate of 85.0%, but still did not meet the discharge standards.

[0070] Table 7. Parameters of Mixed Wastewater

[0071] .

[0072] Table 8. Vapor parameters of mixed wastewater containing light organic components

[0073] .

[0074] Table 9. Parameters of Acid-Containing Concentrate from Mixed Wastewater

[0075] .

[0076] Table 10. Parameters of steam condensate after catalytic oxidation of mixed wastewater

[0077] .

[0078] Example 3: According to as follows Figure 1 The apparatus shown is used for the treatment of mixed wastewater containing acid and biogas slurry in the acidification oil production process. The operation steps are the same as in Example 2, except that the catalyst filling volume in the fixed bed catalytic oxidation tower 11 remains unchanged. The catalyst is composed of iron-based catalyst and platinum-based catalyst (the support is cordierite, and Pt is the active component with a loading of 0.1 wt%) in a volume ratio of 1:1. That is, 50 vol% of platinum-based catalyst is filled on top of 50 vol% iron-based catalyst. The particle size range of the platinum-based catalyst is also 5-8 mesh. Catalytic oxidation is carried out by combining iron-based catalyst and platinum-based catalyst. The remaining operation steps are the same as in Example 2.

[0079] The parameters of the mixed wastewater are shown in Table 7. The parameters of the wastewater vapor containing light organic components formed by the vaporization of the mixed wastewater are shown in Table 8. The parameters of the acid-containing concentrate obtained are shown in Table 9. The parameters of the steam condensate after the catalytic oxidation of the mixed wastewater containing light organic components are shown in Table 11.

[0080] After treatment, the chemical oxygen demand (COD) of the mixed wastewater can be reduced from the initial 20410 mg / L to below 50 mg / L, with a removal rate of over 99.9%, meeting the first-class standard for integrated industrial wastewater discharge; the phosphorus content of the mixed wastewater can be reduced from the initial 1256 mg / L to below 0.1 mg / L, with a removal rate of over 99.9%, meeting the first-class standard for integrated industrial wastewater discharge; and the ammonia nitrogen content of the mixed wastewater can be reduced from the initial 8298 mg / L to below 15 mg / L, with a removal rate of over 99.8%, meeting the first-class standard for integrated industrial wastewater discharge.

[0081] Table 11. Parameters of steam condensate after catalytic oxidation of mixed wastewater

[0082] .

[0083] Example 4: According to as follows Figure 1 The apparatus shown performs a process of long-term circulating alkaline solution treatment. The operation steps are the same as in Example 2, except that the mixed wastewater containing acidic wastewater and biogas slurry in Example 2 is replaced with an equal mass of long-term circulating alkaline solution, which is the alkaline solution that has been recycled for 48 hours in Example 1.

[0084] The parameters of the alkaline solution after 48 hours of recycling in Example 1 are shown in Table 12, the parameters of the steam containing organic light components from the heated and evaporated wastewater are shown in Table 13, the parameters of the concentrated liquid collected from the side line of the outlet pipeline of wastewater circulation pump 5 are shown in Table 14, and the parameters of the steam condensate after catalytic oxidation are shown in Table 15.

[0085] After treatment, the chemical oxygen demand (COD) of the mixed wastewater, after long-term circulation of alkaline solution, decreased from the initial 22,850 mg / L to below 50 mg / L, with a removal rate exceeding 99.8%, meeting the Class I standard for integrated industrial wastewater discharge. The phosphorus content of the mixed wastewater decreased from the initial 3.67 mg / L to below 0.1 mg / L, with a removal rate exceeding 97.3%, also meeting the Class I standard for integrated industrial wastewater discharge. The ammonia nitrogen content of the mixed wastewater decreased from the initial 44.7 mg / L to below 15 mg / L, meeting the Class I standard for integrated industrial wastewater discharge.

[0086] Table 12. Parameters of Alkali Solution After Long-Term Circulation

[0087] .

[0088] Table 13. Steam parameters of wastewater containing organic light components

[0089] .

[0090] Table 14. Concentrate Parameters

[0091] .

[0092] Table 15. Parameters of steam condensate after catalytic oxidation

[0093] .

[0094] Example 5: 50 wt% of the catalytic oxidation steam condensate from Example 1 was added to soapstock, followed by 40 wt% of the acid-containing concentrate from Example 1 (hydrogen ion concentration of 3.75 mol / L). The mixture was stirred at 80 °C for 2 h, allowed to stand, and then separated to obtain the upper acidified oil with a yield of 40.24%.

[0095] According to this embodiment, the acid-containing concentrate obtained by vaporizing and concentrating the steam condensate after catalytic oxidation and the acidic wastewater from the acidified oil production process in Example 1 can be reused in the acidification process to prepare acidified oil.

[0096] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A process for treating acidic wastewater from the production of acidified oil, characterized in that, The apparatus used includes, The wastewater vaporization system includes a heating kettle (9), a wastewater circulation pump (5), and a graphite reboiler (4) connected by a closed-loop pipeline. The acidic wastewater from the acidification oil production process in the bottom of the heating kettle (9) is pumped out by the wastewater circulation pump (5), heated and vaporized through the cold channel of the graphite reboiler (4), and then sent into the top of the heating kettle (9). The acidic wastewater vapor containing organic light components discharged from the top outlet of the heating kettle (9) is sent into the gas phase deacidification system. The gas phase deacidification system uses alkaline solution to absorb and treat acidic wastewater vapor containing light organic components. After deacidification, the wastewater vapor containing light organic components is sent to the gas phase catalytic oxidation system. The gas phase catalytic oxidation system includes an MVR Roots compressor (10), a heat recovery heat exchanger (12), an electromagnetic heater (13), and a fixed bed catalytic oxidation tower (11). After deacidification, the wastewater vapor containing light organic components is compressed and pumped by the MVR Roots compressor (10). The outlet of the MVR Roots compressor (10) is connected by pipelines through the cold channel of the heat recovery heat exchanger (12), the electromagnetic heater (13), the fixed bed catalytic oxidation tower (11), and the hot channel of the heat recovery heat exchanger (12). Air is also introduced into the inlet pipeline of the electromagnetic heater (13). Steam from the outlet of the heat recovery heat exchanger (12) flows through the heat channel of the graphite reboiler (4), and steam and steam condensate discharged from the heat channel of the graphite reboiler (4) enter the cooling discharge system. The heating vessel (9) is provided with a jacket for introducing a heat source, and a steam inlet (f) and a steam outlet (g) are provided on the jacket; the wastewater circulation pump (5) is provided with an acid-containing concentrate outlet (d) on its outlet pipe. The process includes the following steps: 1) Acidic wastewater from the acidification oil production process enters the wastewater vaporization system. It is separated by heating and vaporization in a heating kettle (9) and heating and vaporization in a graphite reboiler (4) to form acidic wastewater vapor containing light organic components. It then enters the gas phase deacidification system. The acidic concentrate obtained by vaporization and concentration is discharged through the acidic concentrate outlet (d) on the side of the outlet pipeline of the wastewater circulation pump (5) and reused in the subsequent acidification process to prepare acidified oil. 2) In the deacidification system, alkaline solution is used to spray and absorb the acidic wastewater vapor containing organic light components in step 1) in the deacidification tower (6) with packing. The wastewater vapor containing organic light components after deacidification enters the gas phase catalytic oxidation system. 3) Wastewater vapor containing light organic components entering the gas phase catalytic oxidation system is compressed and pumped to the cold channel of the heat recovery heat exchanger (12) by the MVR Roots compressor (10). After being heated by heat exchange, it is mixed with the incoming air and heated by the electromagnetic heater (13). Then it enters the fixed bed catalytic oxidation tower (11) for catalytic oxidation reaction. The resulting high-temperature steam first enters the hot channel of the heat recovery heat exchanger (12) and is cooled by heat exchange. Then it is used as the heat source of the graphite reboiler (4) and is cooled by heat exchange before entering the cooling and discharge system. 4) The steam entering the cooling and exhaust system is condensed, the resulting condensate is stored, and the remaining non-condensable air is vented. The absolute pressure inside the heating vessel (9) and the graphite reboiler (4) is 70-100 kPa; In step 3), the catalyst filled inside the fixed-bed catalytic oxidation tower (11) is a combination of iron-based catalyst and platinum-based catalyst; The iron-based catalyst uses red mud as a carrier and Fe2O3 as the active component, with a Fe2O3 loading of 35-40%. The platinum-based catalyst uses cordierite as a support and Pt as the active component, with a loading of 0.05-0.2%.

2. The process as described in claim 1, characterized in that, The gas phase deacidification system includes a deacidification tower (6), an alkali tank (7) and an alkali circulation pump (8). The deacidification tower (6) is filled with packing material, and the bottom air inlet of the deacidification tower (6) is connected to the top air outlet of the heating kettle (9). The alkali solution in the alkali tank (7) is transported to the top of the deacidification tower (6) by the alkali circulation pump (8) to deacidify the rising acidic wastewater vapor containing organic light components. After deacidification, the alkali solution is returned to the alkali tank (7) to form a cycle.

3. The process as described in claim 1, characterized in that, The cooling and exhaust system includes a water storage tank (3), a condenser (2), and a Roots blower (1) connected in sequence by pipelines. After steam and steam condensate enter the cooling and exhaust system, the steam condensate is discharged into the water storage tank (3). The uncondensed steam passes through the water storage tank (3) and enters the condenser (2) for condensation. The resulting condensate is discharged into the water storage tank (3). The remaining non-condensable air is drawn out and discharged by the Roots blower (1).

4. The process as described in claim 1, characterized in that, In step 3), the temperature of the wastewater vapor containing light organic components at the outlet of the MVR Roots compressor (10) is 90-120 ℃. After heat exchange and heating through the cold channel of the heat recovery heat exchanger (12), the temperature is 200-250 ℃. The heating temperature of the electromagnetic heater (13) is 250-300 ℃.

5. The process as described in claim 1, characterized in that, In step 3), the reaction temperature in the fixed-bed catalytic oxidation tower (11) is 250-300 ℃, and the volume ratio of iron-based catalyst to platinum-based catalyst is 1:0.5-2.

6. The process as described in claim 5, characterized in that, The volume ratio of iron-based catalyst to platinum-based catalyst is 1:0.8-1.

2.

7. The process as described in claim 1, characterized in that, In step 3), the temperature of the steam after heat exchange and cooling through the heat recovery heat exchanger (12) is 110-150℃.

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