Alkali residue treatment system and process thereof

Abstract

The invention discloses an alkaline residue treatment system which comprises an alkaline residue storage tank (1), a wet oxidation reactor (2) connected with the alkaline residue storage tank (1), a waste oil storage tank (3), a compressed air buffer tank (4) connected with the wet oxidation reactor (2), a washing tower (5), a deodorized alkali liquor heat exchanger (6) connected with the washing tower (5), and a deodorized waste alkali liquor storage tank (7) connected with the deodorized alkali liquor heat exchanger (6), the pipeline mixer (8) is connected with the deodorized waste alkali liquor storage tank (7); and the concentrated sulfuric acid storage tank (9) and the neutralization tank (10) are connected with the pipeline mixer (8). According to the alkaline residue treatment system and the process thereof, the treatment effect of waste alkaline residues can be effectively improved, and emission meets the environmental protection requirement.

Description

Technical Field

[0001] The invention relates to the technical field of alkali slag treatment, and in particular to an alkali slag treatment system and a process thereof. Background Art

[0002] Although the flow rate of ethylene alkali slag and liquefied gas alkali slag wastewater is small, due to the high concentration of organic matter, high sulfide content and high alkalinity, it may have an impact on the subsequent biochemical treatment and affect the wastewater treatment effect of the power plant. In particular, if the sulfide content is high and the neutralization measures are not appropriate, it may cause hydrogen sulfide gas to overflow, bring safety risks and affect the surrounding environment. In addition, a large number of oligomers in the alkali slag of this project form butter, which is easy to agglomerate when entering the sewage treatment system, affecting sewage production. Based on the principles of low investment, simple operation and reliable and sufficient raw material sources, a point source control plan is adopted to reduce the sulfide (S 2－ ) content to meet the sewage inlet requirements of the downstream sewage treatment plant.

[0003] There are five main industrial alkali slag treatment processes: sulfuric acid acidification, incineration, dilution treatment, wet oxidation, and alkali slag treatment using catalytic cracking regeneration flue gas neutralization and advanced oxidation combined process. In the process of adding acid to adjust the pH value, sulfuric acid acidification cannot avoid gas pollution such as HS and VOC, which poses a great environmental and safety hazard. Toxic and harmful gases such as SO generated by the incineration method will pollute the surrounding atmospheric environment: at the same time, since fuel oil or gas is required for combustion, the cost of treatment is extremely high. Since the concentration of pollutants in alkali slag wastewater is hundreds of times the influent index of general sewage treatment plants, the dilution treatment method requires the sewage treatment plant to be much larger in scale, and additional wastewater treatment facilities need to be added, resulting in excessive investment costs and a large area; if the dilution multiple is limited, the sewage treatment plant will be overloaded due to the excessive influent index of the sewage treatment plant, which directly leads to unstable operation. Wet oxidation has a good effect on alkali slag wastewater, but its operating conditions are harsh (WAO) and the process requires high temperature and high pressure. It is deodorized by moderate wet air oxidation (WAO). In the WAO unit, inorganic and organic sulfides in the waste alkali liquor are oxidized into thiosulfate, sulfite and phosphate, thereby achieving the purpose of deodorization and reducing the amount of acid used in the subsequent acidification process. The method of treating alkali residue wastewater using catalytic cracking regeneration flue gas is to blend the alkali liquor or alkali residue produced by gasoline refining with the alkali liquor or alkali residue produced by liquefied gas refining, and introduce catalytic cracking regeneration flue gas into the blended waste alkali liquor or alkali residue for neutralization reaction to reduce the pH value. The regeneration flue gas of the fluidized catalytic cracking unit mainly includes acid gases CO, SO and NOx, and the acid gas neutralizes the NaOH, sodium phenol, sodium cyclopentaneate and sodium sulfide in the waste alkali liquor or alkali residue and converts them into sodium carbonate and phenol, cyclopentane acid and hydrogen sulfide; so as to further separate the oil and phenol, cyclopentane acid, sulfide and the like in the waste alkali liquor or alkali residue. The treatment steps include multi-stage sedimentation, advanced oxidation, flocculation, and filter press processes to further extract crude phenol, cyclohexane acid, etc.; the treated water is discharged in a managed manner to an existing sewage treatment plant for comprehensive treatment.

[0004] Application number CN 202110797562.3 discloses a system and method for treating petrochemical alkali slag, which belongs to the technical field of petrochemical alkali slag treatment, and solves the technical problems that the existing petrochemical alkali slag treatment methods are complicated, the energy consumption is roughly poor in economy and the environmental protection is poor. The treatment system includes a sintering flue gas acidification unit, a desulfurization ash calcification unit and a sintering machine detoxification unit connected in sequence; the sintering flue gas acidification unit is connected to the sintering flue gas main pipeline, and the sintering flue gas acidification unit is also connected to the sintering flue gas treatment system; the petrochemical alkali slag is passed into the sintering flue gas acidification unit for acidification treatment; the desulfurization ash calcification unit is used to perform a calcification reaction on the acidified waste liquid; the calcification product is separated into solid and liquid, the solid precipitate is sent to the lime kiln, and the alkali slag liquid is sent to the sintering machine detoxification unit; the sintering machine detoxification unit is used to perform high-temperature detoxification on the residual neutral oil and organic acidic substances in the alkali slag liquid. Summary of the invention

[0005] The present invention aims to overcome the technical problem that the sulfuric acid acidification method in the prior art cannot effectively remove pollutants in alkali slag wastewater and has environmental and safety hazards, and provides an alkali slag treatment system and process thereof, which can effectively improve the treatment effect of waste alkali slag and the discharge meets environmental protection requirements.

[0006] The present invention provides an alkali residue treatment system, comprising an alkali residue storage tank, a wet oxidation reactor and a waste oil storage tank connected to the alkali residue storage tank, a compressed air buffer tank and a washing tower connected to the wet oxidation reactor, a deodorized alkali liquid heat exchanger connected to the washing tower, a deodorized waste alkali liquid storage tank connected to the deodorized alkali liquid heat exchanger, a pipeline mixer connected to the deodorized waste alkali liquid storage tank, and a concentrated sulfuric acid storage tank and a neutralization tank connected to the pipeline mixer;

[0007] The wet oxidation reactor is connected to the steam network, the waste oil storage tank is connected to the waste oil recovery station, and the neutralization tank is connected to the sewage treatment station;

[0008] A feed pump is provided between the alkali residue storage tank and the wet oxidation reactor, a waste alkali liquid circulation pump is provided between the washing tower and the deodorized alkali liquid heat exchanger, a liquid level regulating valve is provided between the deodorized alkali liquid heat exchanger and the deodorized waste alkali liquid storage tank, a waste oil pump is provided between the waste oil storage tank and the waste oil recovery station, an air compressor is provided on the compressed air buffer tank, a neutralization pump is provided between the deodorized waste alkali liquid storage tank and the pipeline mixer, a concentrated sulfuric acid pump is provided between the concentrated sulfuric acid storage tank and the pipeline mixer, and a delivery pump is provided between the neutralization tank and the sewage treatment station.

[0009] The alkali slag treatment system described in the present invention is, as a preferred embodiment, a wet oxidation reactor comprising an inner cylinder, an outer cylinder arranged outside the inner cylinder, a feed port arranged at the upper part of the outer cylinder, an air inlet and a steam inlet arranged at the lower part of the inner cylinder, an air distributor connected to the air inlet, a steam distributor connected to the steam inlet and a discharge port arranged above the inner cylinder.

[0010] The alkali residue treatment system described in the present invention is preferably configured such that the feed pump, the waste alkali solution circulation pump, the neutralization pump, the concentrated sulfuric acid pump and the delivery pump are all in two groups, one for standby and the other for use.

[0011] In the alkaline slag treatment system described in the present invention, as a preferred embodiment, there are two sets of air compressors, one for backup and the other for use.

[0012] The method for using the alkali slag treatment system of the present invention comprises the following steps:

[0013] S1, sedimentation separation: transport the alkali residue to be treated to the alkali residue storage tank for static sedimentation to separate the butter and waste alkali residue;

[0014] S2, wet oxidation reaction: the waste alkali residue is introduced from the feed port into the space between the inner cylinder and the outer cylinder of the wet oxidation reactor, and is preheated while flowing downward, and the sulfide is oxidized by the dissolved oxygen in the internal reflux; the air is pressurized by the air compressor and enters the inner cylinder through the compressed air buffer tank, the air inlet, and the air distributor to mix with the waste alkali residue; the steam enters the inner cylinder through the steam inlet and the steam distributor to mix with the waste alkali residue and heat the waste alkali residue; the waste alkali residue reacts and flows upward in the inner cylinder under the heating effect of steam and the lifting effect of air, and is discharged from the discharge port;

[0015] S3, alkali residue washing: the mixture of air and waste alkali liquid discharged from the discharge port enters the lower part of the washing tower for gas-liquid separation, and the liquid is transferred from the bottom of the washing tower to the deodorizing alkali residue heat exchanger, cooled to 40°C by circulating cooling water, and pressurized by the waste alkali liquid circulating pump. A part of it flows back to the middle and upper part of the washing tower through the flow meter and flow regulating valve, and the other part enters the deodorizing waste alkali liquid storage tank through the liquid level regulating valve; the gas phase mixture moves to the upper part of the washing tower and contacts with the refluxed cold alkali liquid, wherein the water vapor and volatile organic matter are condensed and cooled and then return to the bottom of the washing tower, and the tail gas is further condensed to 40°C and discharged from the top of the washing tower;

[0016] S4, neutralization: the alkali liquid in the deodorized waste alkali liquid storage tank is transferred to the pipeline mixer through the neutralization pump, and at the same time, 98% concentrated sulfuric acid is transferred from the concentrated sulfuric acid storage tank to the pipeline mixer through the concentrated sulfuric acid pump to mix with the alkali liquid, and then transferred to the neutralization tank, and the pH in the neutralization tank is 6-9; the neutralized waste alkali liquid is transferred to the sewage treatment station by the delivery pump.

[0017] The method for using the alkali residue treatment system of the present invention, as a preferred embodiment, further comprises the following steps:

[0018] S5. Butter treatment: The butter separated from the alkali residue storage tank is discharged into the waste oil storage tank, and after further dehydration, it is transported to the waste oil recovery station by the waste oil pump.

[0019] The present invention has the following advantages:

[0020] (1) The wet oxidation reactor uses oxygen in the air to oxidize the sulfide in the waste alkali liquid into thiosulfate, sulfite or sulfate at a certain temperature and pressure, remove the odor in the waste alkali liquid, partially oxidize organic matter such as phenol, and improve the biodegradability of the waste alkali liquid;

[0021] (2) All process liquid vents in this system are connected to the process liquid vent main pipeline, and are treated uniformly after recovery and are not discharged into the factory sewage system; the concentrations of hydrogen sulfide and non-methane total hydrocarbons in the exhaust gas are lower than the limit values ​​of China's national standards GB14554-93 "Emission Standards for Odor Pollutants" and GB16297-1996 "Comprehensive Emission Standards for Air Pollutants", which meet environmental protection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a composition diagram of an alkali slag treatment system;

[0023] Figure 2 It is a composition diagram of a wet oxidation reactor of an alkali slag treatment system;

[0024] Figure 3 The present invention is a flow chart of a method for using an alkali slag treatment system.

[0025] Reference numerals:

[0026] 1. Alkali residue storage tank; 2. Wet oxidation reactor; 21. Inner cylinder; 22. Outer cylinder; 23. Feed inlet; 24. Air inlet; 25. Steam inlet; 26. Air distributor; 27. Steam distributor; 28. Discharge port; 3. Waste oil storage tank; 4. Compressed air buffer tank; 5. Scrubber; 6. Deodorized alkali liquid heat exchanger; 7. Deodorized waste alkali liquid storage tank; 8. Pipeline mixer; 9. Concentrated sulfuric acid storage tank; 10. Neutralization tank; 11. Feed pump; 12. Waste alkali liquid circulation pump; 13. Liquid level regulating valve; 14. Sewage oil pump; 15. Air compressor; 16. Neutralization pump; 17. Concentrated sulfuric acid pump; 18. Delivery pump. DETAILED DESCRIPTION

[0027] Example 1

[0028] like Figure 1 As shown, a alkali residue treatment system includes an alkali residue storage tank 1, a wet oxidation reactor 2 connected to the alkali residue storage tank 1, a waste oil storage tank 3, a compressed air buffer tank 4 connected to the wet oxidation reactor 2, a washing tower 5, a deodorized alkali liquid heat exchanger 6 connected to the washing tower 5, a deodorized waste alkali liquid storage tank 7 connected to the deodorized alkali liquid heat exchanger 6, a pipeline mixer 8 connected to the deodorized waste alkali liquid storage tank 7, and a concentrated sulfuric acid storage tank 9 and a neutralization tank 10 connected to the pipeline mixer 8;

[0029] like Figure 2 As shown, the wet oxidation reactor 2 includes an inner cylinder 21, an outer cylinder 22 arranged outside the inner cylinder 21, a material inlet 23 arranged at the upper part of the outer cylinder 22, an air inlet 24 and a steam inlet 25 arranged at the lower part of the inner cylinder 21, an air distributor 26 connected to the air inlet 24, a steam distributor 27 connected to the steam inlet 25, and a material outlet 28 arranged above the inner cylinder 21;

[0030] The wet oxidation reactor 2 is connected to the steam network, the waste oil storage tank 3 is connected to the waste oil recovery station, and the neutralization tank 10 is connected to the sewage treatment station;

[0031] A feed pump 11 is provided between the alkali residue storage tank 1 and the wet oxidation reactor 2, a waste alkali liquid circulation pump 12 is provided between the washing tower 5 and the deodorized alkali liquid heat exchanger 6, a liquid level regulating valve 13 is provided between the deodorized alkali liquid heat exchanger 6 and the deodorized waste alkali liquid storage tank 7, a waste oil pump 14 is provided between the waste oil storage tank 3 and the waste oil recovery station, an air compressor 15 is provided on the compressed air buffer tank 4, a neutralization pump 16 is provided between the deodorized waste alkali liquid storage tank 7 and the pipeline mixer 8, a concentrated sulfuric acid pump 17 is provided between the concentrated sulfuric acid storage tank 9 and the pipeline mixer 8, and a delivery pump 18 is provided between the neutralization tank 10 and the sewage treatment station.

[0032] The feed pump 11, the waste alkali liquid circulation pump 12, the neutralization pump 16, the concentrated sulfuric acid pump 17, the delivery pump 18, and the air compressor 15 are all in two sets, one for backup and the other for use.

[0033] During use of this embodiment, Figure 3 As shown, the following steps are included:

[0034] S1, sedimentation separation: transport the alkali residue to be treated to the alkali residue storage tank 1 for static sedimentation to separate the butter and the waste alkali residue;

[0035] S2, wet oxidation reaction: the waste alkali residue enters the inner cylinder 21 and the outer cylinder 22 of the wet oxidation reactor 2 from the feed port 23, and is preheated while flowing downward, and the sulfide is oxidized by the dissolved oxygen in the internal reflux; the air is pressurized by the air compressor 15 and enters the inner cylinder 21 through the compressed air buffer tank 4, the air inlet 24, and the air distributor 26 to mix with the waste alkali residue; the steam enters the inner cylinder 21 through the steam inlet 25 and the steam distributor 27 to mix with the waste alkali residue and heat the waste alkali residue; the waste alkali residue reacts and flows upward in the inner cylinder 21 under the heating effect of steam and the lifting effect of air, and is discharged from the discharge port 28;

[0036] S3, alkali residue washing: the mixture of air and waste alkali liquid discharged from the discharge port 28 enters the lower part of the washing tower 5 for gas-liquid separation, and the liquid is transferred from the bottom of the washing tower 5 to the deodorizing alkali residue heat exchanger 6, and is cooled to 40°C by circulating cooling water, and is pressurized by the waste alkali liquid circulating pump 12. A part of it flows back to the middle and upper part of the washing tower 5 through the flow meter and the flow regulating valve, and the other part enters the deodorizing waste alkali liquid storage tank 7 through the liquid level regulating valve 13; the gas phase mixture moves to the upper part of the washing tower 5 and contacts with the refluxed cold alkali liquid, wherein the water vapor and volatile organic matter are condensed and cooled and then return to the bottom of the washing tower 5, and the tail gas is further condensed to 40°C and discharged from the top of the washing tower 5;

[0037] S4, neutralization: the alkali liquid in the deodorized waste alkali liquid storage tank 7 is transferred to the pipeline mixer 8 by the neutralization pump 16, and at the same time, 98% concentrated sulfuric acid is transferred from the concentrated sulfuric acid storage tank 9 to the pipeline mixer 8 by the concentrated sulfuric acid pump 17 to mix with the alkali liquid, and then transferred to the neutralization tank 10, and the pH in the neutralization tank 10 is 6-9; the neutralized waste alkali liquid is transferred to the sewage treatment station by the delivery pump 18;

[0038] S5, butter processing: the butter separated from the alkali residue storage tank 1 is discharged into the waste oil storage tank 3, and after further dehydration, it is transferred to the waste oil recovery station by the waste oil pump 14.

[0039] The above description is only illustrative rather than restrictive of the present invention. Those skilled in the art will understand that any modification, change or equivalent that can be made without departing from the spirit and scope defined by the claims will fall within the protection scope of the present invention.

Claims

1. A caustic slag treatment system, characterized in that: The invention comprises an alkali residue storage tank (1), a wet oxidation reactor (2) and a waste oil storage tank (3) connected to the alkali residue storage tank (1), a compressed air buffer tank (4) and a washing tower (5) connected to the wet oxidation reactor (2), a deodorized alkali liquid heat exchanger (6) connected to the washing tower (5), a deodorized waste alkali liquid storage tank (7) connected to the deodorized alkali liquid heat exchanger (6), a pipeline mixer (8) connected to the deodorized waste alkali liquid storage tank (7), and a concentrated sulfuric acid storage tank (9) and a neutralization tank (10) connected to the pipeline mixer (8); The wet oxidation reactor (2) is connected to a steam network, the waste oil storage tank (3) is connected to a waste oil recovery station, and the neutralization tank (10) is connected to a sewage treatment station; A feed pump (11) is provided between the alkali residue storage tank (1) and the wet oxidation reactor (2); a waste alkali liquid circulation pump (12) is provided between the washing tower (5) and the deodorized alkali liquid heat exchanger (6); a liquid level regulating valve (13) is provided between the deodorized alkali liquid heat exchanger (6) and the deodorized waste alkali liquid storage tank (7); a waste oil pump (14) is provided between the waste oil storage tank (3) and the waste oil recovery station; an air compressor (15) is provided on the compressed air buffer tank (4); a neutralization pump (16) is provided between the deodorized waste alkali liquid storage tank (7) and the pipeline mixer (8); a concentrated sulfuric acid pump (17) is provided between the concentrated sulfuric acid storage tank (9) and the pipeline mixer (8); and a delivery pump (18) is provided between the neutralization tank (10) and the sewage treatment station.

2. A caustic slag treatment system according to claim 1, characterized in that: The wet oxidation reactor (2) comprises an inner cylinder (21), an outer cylinder (22) arranged outside the inner cylinder (21), a feed port (23) arranged at the upper part of the outer cylinder (22), an air inlet (24) and a steam inlet (25) arranged at the lower part of the inner cylinder (21), an air distributor (26) connected to the air inlet (24), a steam distributor (27) connected to the steam inlet (25), and a discharge port (28) arranged above the inner cylinder (21).

3. The alkali residue treatment system according to claim 1, characterized in that: The feed pump, the waste alkali solution circulation pump (12), the neutralization pump (16), the concentrated sulfuric acid pump (17), and the delivery pump (18) are all in two groups, one for standby and the other for use.

4. The alkali residue treatment system according to claim 1, characterized in that: The air compressors (15) are in two sets, one for standby and one for use.

5. The method for using the alkali residue treatment system according to claim 2, characterized in that: The following steps are involved: S1, sedimentation separation: transporting the alkali residue to be treated into the alkali residue storage tank (1) for static sedimentation to separate the butter and the waste alkali residue; S2, wet oxidation reaction: the waste alkali slag enters the inner cylinder (21) and the outer cylinder (22) of the wet oxidation reactor (2) from the feed port (23), is preheated while flowing downward, and the sulfide is oxidized by the dissolved oxygen in the internal reflux; air is pressurized by the air compressor (15) and enters the inner cylinder (21) through the compressed air buffer tank (4), the air inlet (24), and the air distributor (26) to mix with the waste alkali slag; steam enters the inner cylinder (21) through the steam inlet (25) and the steam distributor (27) to mix with the waste alkali slag and heat the waste alkali slag; the waste alkali slag reacts and flows upward in the inner cylinder (21) under the heating effect of steam and the lifting effect of air, and is discharged from the discharge port (28); S3, alkali residue washing: the mixture of air and waste alkali liquid discharged from the discharge port (28) enters the lower part of the washing tower (5) for gas-liquid separation, and the liquid is transferred from the bottom of the washing tower (5) to the deodorizing alkali residue heat exchanger (6), cooled to 40°C by circulating cooling water, and pressurized by the waste alkali liquid circulation pump (12). A part of it flows back to the middle and upper part of the washing tower (5) through a flow meter and a flow regulating valve, and the other part enters the deodorizing waste alkali liquid storage tank (7) through a liquid level regulating valve (13); the gas phase mixture moves to the upper part of the washing tower (5) and contacts with the refluxed cold alkali liquid, wherein the water vapor and volatile organic matter are condensed and cooled and then return to the bottom of the washing tower (5), and the tail gas is further condensed to 40°C and discharged from the top of the washing tower (5); S4, neutralization: the alkali liquid in the deodorized waste alkali liquid storage tank (7) is transferred to the pipeline mixer (8) through the neutralization pump (16), and at the same time, 98% concentrated sulfuric acid is transferred from the concentrated sulfuric acid storage tank (9) to the pipeline mixer (9) through the concentrated sulfuric acid pump (17) to mix with the alkali liquid, and then transferred to the neutralization tank (10), the pH in the neutralization tank (10) is 6 to 9; the neutralized waste alkali liquid is transferred to the sewage treatment station by the transfer pump (18).

6. The method for using the alkali residue treatment system according to claim 3, characterized in that: The following steps are also included: S5, butter processing: the butter separated from the alkali residue storage tank (1) is discharged into the waste oil storage tank (3), and after further dehydration, is transferred to the waste oil recovery station by the waste oil pump (14).

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