Deep oil removal treatment process and device for acidic water

Abstract

The invention discloses an acidic water deoiling treatment process and device in the field of petrochemical engineering. The device comprises an acidic water pressure pump, an acidic water preheater, an acidic water dealkylation tower, a condenser and a liquid separation tank, the device is characterized in that the acidic water pressure pump, the acidic water preheater and the acidic water dealkylation tower are sequentially connected through acidic water pipelines, and the acidic water dealkylation tower is sequentially connected with the condenser and the liquid separation tank through the tower top. The method can improve the purity of the by-product acidic gas in the purification section of the downstream acidic water stripping device and reduce the hydrocarbon content in the acidic gas; meanwhile, most oil-gas resources are recovered.

Description

Technical Field

[0001] The invention relates to the technical field of acidic water treatment, in particular to an acidic water deoiling pretreatment process and a device. Technical Background

[0002] The sulfur-containing acidic water in the petrochemical and coal chemical industries generally contains more than 1000 mg / l of oil, and its state can be roughly divided into volatile oil, floating oil, dispersed oil, emulsified oil and dissolved oil. Acidic water pretreatment generally removes volatile oil (light hydrocarbons) by depressurizing and degassing, removes floating oil by atmospheric pressure sedimentation, and removes dispersed oil by mechanical coalescence filtration. Usually, emulsified oil and dissolved oil cannot be removed from acidic water after pretreatment, and only volatile oil, floating oil and part of dispersed oil can be removed. The oil content in acidic water is still as high as 100-200 mg / l or more. The oil content in acidic water will affect the quality of by-products in the purification section of the downstream acidic water stripping device, making the hydrocarbon content of the by-product acid gas too high and unable to be used as a raw material for the sulfur recovery device; the by-product ammonia gas is seriously loaded with hydrocarbons, and it is impossible to produce by-product liquid ammonia or ammonia water.

[0003] Chinese patent CN111689599A discloses an acidic water deoiling pretreatment process, which includes firstly removing oil from oily wastewater through a tank-in-tank, then reducing SS suspended solids above 1 micron in acidic water through a self-cleaning microfilter, then further removing oil content through a Zhenjing oil-water separator, and finally removing dissolved oil in acidic water through a hollow membrane filter. The oil content of the inlet water of the above-mentioned tank-in-tank is ≤15000mg / l, and the oil content of the treated wastewater is ≤150mg / l through hydrocyclone separation, floating oil collection and oil discharge; the oil content of the inlet water of the Zhenjing oil-water separator should be controlled at ≤300mg / l, and the filter element made of graphene-based oleophilic and hydrophobic materials is used to effectively treat emulsified oil and dissolved oil, and the oil content of the treated wastewater is ≤20-50mg / l; the hollow membrane filter uses a hollow membrane component to block and aggregate dissolved oil in acidic water, and the total oil content of the treated oily wastewater is ≤20mg / l. This process can better solve the oil content requirement of the inlet water for acidic water stripping, but there is secondary sewage discharge during the treatment process, and consumables such as filter rods, filter elements and hollow membrane components need to be replaced. Summary of the invention

[0004] The present invention aims at the problems existing in the prior art and provides a deep oil removal treatment process and device for acidic water.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] The present invention provides an acidic water deep oil removal treatment process, comprising the following steps:

[0007] 1) The pretreated acidic water is pressurized by an acidic water booster pump;

[0008] 2) The acidic water after the pressure increase in step 1) is heated by an acidic water preheater;

[0009] 3) the acidic water heated in step 2) enters the acidic water dehydrogenation tower for stripping to remove the oil in the acidic water;

[0010] 4) The oil-containing water vapor at the top of the acid water dehydrogenation tower is condensed by a condenser, and then separated into water phase, oil phase and light hydrocarbon non-condensable gas by a separator. The water phase is used as the top reflux liquid of the acid water dehydrogenation tower, and the oil phase is used as the light oil by-product; the light hydrocarbon non-condensable gas is sent to the flare system;

[0011] 5) The deoiled acidic water discharged from the bottom of the acidic water dehydrogenation tower is heat exchanged in the acidic water preheater and sent to the purification section of the acidic water stripping device;

[0012] 6) Use low-pressure steam to provide a heat source for step 3).

[0013] The invention provides a deep oil removal treatment process for acidic water, which is further characterized in that the total oil content of the deoiled acidic water discharged from the bottom of the acidic water dehydrogenation tower is less than 10 mg / l.

[0014] The invention provides a deep oil removal process for acidic water, which is further characterized in that: the low-pressure steam in step 6) indirectly provides a heat source for step 3) through a reboiler.

[0015] The acid water deep oil removal treatment process provided by the present invention removes the oil content in the acid water by preheating and stripping, thereby ensuring that the acid gas and ammonia gas generated by the acid water stripping device are qualified.

[0016] The invention provides an acidic water deep oil removal treatment process, which is further characterized in that the preheating temperature range of the acidic water after heating in step 2) is 60-110°C.

[0017] The invention discloses an acidic water deep oil removal treatment process, which is further characterized in that: the operating temperature range of the acidic water dehydrogenation tower top is 90-120°C, the operating pressure range is normal pressure-0.2MPaG; the operating temperature range of the condenser outlet is 40-80°C.

[0018] The present invention also provides an acidic water deep oil removal treatment device for carrying out the above-mentioned acidic water deep oil removal treatment process, specifically:

[0019] A deep oil removal treatment device for acidic water mainly comprises an acidic water pressure pump, an acidic water preheater, an acidic water dehydrogenation tower, a condenser and a liquid separator; the characteristic is that the acidic water pressure pump, the acidic water preheater and the acidic water dehydrogenation tower are connected in sequence through an acidic water pipeline, the acidic water dehydrogenation tower is connected to the condenser and the liquid separator from the top of the tower through an oil-containing water vapor pipeline, and the acidic water dehydrogenation tower is connected to the acidic water preheater from the bottom of the tower through a deoiled acidic water pipeline.

[0020] The invention discloses an acidic water deep oil removal treatment device, which is further characterized in that low-pressure steam is used to directly provide a heat source for the acidic water dehydrogenation tower kettle.

[0021] The invention provides an acidic water deep oil removal treatment device, which is further characterized in that it also includes a reboiler, and low-pressure steam indirectly provides a heat source for the acidic water dehydrogenation tower kettle through the reboiler.

[0022] By adopting the above technology, compared with the prior art, the beneficial effects of the present invention are as follows: improving the purity of the by-product acid gas in the purification section of the downstream acid water stripping device, reducing the hydrocarbon content in the acid gas; and recovering most of the oil and gas resources at the same time.

[0023] The present invention removes the oil content in the acidic water by setting an acidic water dehydrogenation tower. The acidic water after sedimentation and deoiling is heat exchanged with the acidic water at the bottom of the acidic water dehydrogenation tower by a preheater and enters the upper part of the acidic water dehydrogenation tower. After steam stripping in the tower, the gas phase at the top of the tower is condensed and separated, the water phase is refluxed, the oil phase is collected separately, and the non-condensable gas is sent to the flare system. The acidic water after deoiling at the bottom of the tower is heat exchanged and sent to the purification section of the acidic water stripping device to recover qualified acid gas and ammonia.

[0024] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the scope of application of the present invention is not limited thereto. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a schematic diagram of a process flow of deep oil removal treatment of acidic water according to the present invention.

[0026] Figure 2 The figure is a schematic diagram of the process flow of the present invention containing a reboiler.

[0027] The figures shown therein are marked as follows: 1-acid water booster pump; 2-acid water preheater; 3-acid water dehydrogenation tower; 4-condenser; 5-separator; 6-reboiler; 101-oil-containing acid water; 102-deoiled acid water; 103-oil-containing water vapor; 104-reflux liquid; 105-light oil by-product; 106-light hydrocarbon non-condensable gas; 107-reboiler feed; 108-reboiler return tower steam; 109-low-pressure steam; 110-low-pressure condensate. DETAILED DESCRIPTION

[0028] The following is combined with Figure 1 and attached Figure 2 The present invention is further described.

[0029] As attached Figure 1As shown, the pretreated oil-containing acidic water 101 is pressurized by the acidic water booster pump 1, and heat-exchanged by the acidic water preheater 2, so that the temperature of the oil-containing acidic water is raised from room temperature to 60-110°C, and the heated oil-containing acidic water enters the upper part of the acidic water dehydrogenation tower 3. The oil-containing acidic water is subjected to mass transfer and heat transfer exchange through multiple layers of trays or fillers in the acidic water dehydrogenation tower 3, and the oil-containing water vapor 103 at 90-120°C is discharged from the top of the acidic water dehydrogenation tower 3, condensed to 40-80°C by the condenser 4, and enters the liquid separator 5 for three-phase separation, the water phase is used as the top reflux liquid 104 of the acidic water dehydrogenation tower, the oil phase is used as the light oil byproduct 105 to the light dirty oil system, and the gas phase is the light hydrocarbon non-condensable gas discharged to the low-pressure flare system. The deoiled acidic water 102 is discharged from the bottom of the acidic water dehydrogenation tower 3, and is sent to the purification section of the acidic water stripping device after heat exchange in the acidic water preheater 2. The heat source of the sour water dehydrogenation tower 3 is directly provided by the low-pressure steam 109 .

[0030] As attached Figure 2 As shown, the pretreated oil-containing acidic water 101 is pressurized by the acidic water booster pump 1, and heat-exchanged by the acidic water preheater 2, so that the temperature of the oil-containing acidic water is raised from room temperature to 60-110°C, and the heated oil-containing acidic water enters the upper part of the acidic water dehydrogenation tower 3. The oil-containing acidic water is subjected to mass transfer and heat transfer exchange through multiple layers of trays or fillers in the acidic water dehydrogenation tower 3, and the oil-containing water vapor 103 at 90-120°C is discharged from the top of the acidic water dehydrogenation tower 3, condensed to 40-80°C by the condenser 4, and enters the liquid separator 5 for three-phase separation, the water phase is used as the top reflux liquid 104 of the acidic water dehydrogenation tower, the oil phase is used as the light oil byproduct 105 to the light dirty oil system, and the gas phase is the light hydrocarbon non-condensable gas discharged to the low-pressure flare system. The deoiled acidic water 102 is discharged from the bottom of the acidic water dehydrogenation tower 3, and is sent to the purification section of the acidic water stripping device after heat exchange in the acidic water preheater 2. The heat source of the sour water dehydrogenation tower 3 is provided by the reboiler 6 through the circulating evaporation of the reboiler feed 107 to form the reboiler return tower steam 108; the heat source of the reboiler 6 is provided by the low-pressure steam 109 condensed into low-pressure condensate 110.

[0031] Benefits of the present invention: The deep oil removal process for acidic water provided by the present invention ensures that the total oil content in the deoiled acidic water is less than 10 mg / l through preheating, stripping and other processes, and ensures that the acid gas and ammonia generated by the acidic water stripping device are qualified.

[0032] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A deep deoiling process for acidic water, comprising the following steps: 1) The pretreated acidic water is pressurized by an acidic water booster pump; 2) The acidic water after the pressure increase in step 1) is heated by an acidic water preheater; 3) the acidic water heated in step 2) enters the acidic water dehydrogenation tower for stripping to remove the oil in the acidic water; 4) The oil-containing water vapor at the top of the acid water dehydrogenation tower is condensed by a condenser, and then separated into water phase, oil phase and light hydrocarbon non-condensable gas by a separator. The water phase is used as the top reflux liquid of the acid water dehydrogenation tower, and the oil phase is used as the light oil by-product; the light hydrocarbon non-condensable gas is sent to the flare system; 5) The deoiled acidic water discharged from the bottom of the acidic water dehydrogenation tower is heat exchanged in the acidic water preheater and sent to the purification section of the acidic water stripping device; 6) Use low-pressure steam to provide a heat source for step 3).

2. The acidic water deep oil removal treatment process according to claim 1, characterized in that: In step 6), the low-pressure steam passes through a reboiler to indirectly provide a heat source for step 3).

3. The acidic water deep oil removal treatment process according to claim 1, characterized in that: The total oil content of the deoiled acidic water discharged from the bottom of the acidic water dehydrogenation tower is less than 10 mg / l.

4. The acidic water deep oil removal treatment process according to claim 1, characterized in that: The preheating temperature of the acidic water after heating in step 2) is in the range of 60 to 110°C.

5. The acidic water deep oil removal treatment process according to claim 1, characterized in that: The operating temperature range of the acidic water dehydrogenation tower top is 90-120° C., and the operating pressure range is normal pressure to 0.2 MPaG.

6. The acidic water deep oil removal treatment process according to claim 1, characterized in that: The operating temperature range of the condenser outlet is 40-80°C.

7. An acidic water deep oil removal treatment device, mainly comprising an acidic water pressure pump, an acidic water preheater, an acidic water dehydrogenation tower, a condenser and a liquid separator; characterized in that: The acid water booster pump, acid water preheater and acid water dehydrogenation tower are connected in sequence through an acid water pipeline. The acid water dehydrogenation tower is connected to the condenser and the liquid separator from the top through an oil-containing water vapor pipeline. The acid water dehydrogenation tower is connected to the acid water preheater from the bottom through a deoiled acid water pipeline.

8. The acidic water deep oil removal treatment device according to claim 7, characterized in that: Low-pressure steam is used to directly provide heat source for the bottom of the acid water dehydrogenation tower.

9. The acidic water deep oil removal treatment device according to claim 7, characterized in that: The invention also comprises a reboiler, through which low-pressure steam indirectly provides a heat source for the bottom of the acid water dehydrogenation tower.

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