Equipment and method for continuously treating sodium nitrite passivation wastewater

Abstract

The invention relates to the technical field of waste liquid treatment, and discloses equipment for continuously treating sodium nitrite passivation wastewater, the equipment comprises a premixing unit, a main reaction unit and a pH online detection unit, the premixing unit is provided with a sulfamic acid feeding port and is communicated with a wastewater feeding pipeline, and the main reaction unit is communicated with the wastewater feeding pipeline; a feeding regulating valve and a feeding flow meter are mounted on the wastewater feeding pipeline; the main reaction unit comprises a reactor communicated with the premixing unit so as to reduce the total nitrogen content in the wastewater; the reactor is communicated with the premixing unit through a return pipe; and the pH online detection unit is used for performing pH online detection on the wastewater in the wastewater discharge pipeline so as to adjust the flow of the sodium nitrite passivation wastewater entering the reactor. The device has the advantages that the feeding amount can be controlled, the sodium nitrite passivation wastewater can be continuously treated, and the treatment effect is good.

Description

Technical Field

[0001] The invention relates to the technical field of waste liquid treatment, and in particular to a device and a method for continuously treating sodium nitrite passivation waste water. Background Art

[0002] In order to ensure long-term stable operation and product quality of equipment during the construction of new facilities in the petrochemical, steel and other industries or when they are shut down for major overhauls, chemical cleaning will be carried out on equipment and pipelines before they are put into use to remove surface dirt formed during installation or operation. Chemical cleaning mainly includes acid cleaning, passivation and other steps. The wastewater produced has the characteristics of concentrated discharge time and high pollutant concentration. In particular, the sodium nitrite passivation wastewater has a total nitrogen concentration of up to 1000-6000 mg / L. If it is discharged directly without proper pretreatment, it will cause serious impact on the biochemical system of the downstream sewage treatment plant, and then lead to environmental incidents. Traditional chemical cleaning operations are generally not equipped with dedicated wastewater pretreatment equipment. The conventional practice is to use the following: Figure 2 In the cleaning tank shown, the aminosulfonic acid raw material and other reagents are directly added into the cleaning tank, and the wastewater is sent out after simple pH control. This method requires intermittent operation, and it is difficult to accurately control the amount of reagent added, and the treatment effect is difficult to guarantee. It is not suitable for continuous pretreatment of large amounts of passivation wastewater. Therefore, it is necessary to develop a device with a high degree of automation, simple operation, and continuous treatment of sodium nitrite passivation wastewater. Summary of the invention

[0003] The purpose of the present invention is to overcome the current situation in the prior art that traditional chemical cleaning operations require intermittent operation, it is difficult to accurately control the amount of reagent added, the treatment effect is difficult to guarantee, and it is not suitable for continuous pretreatment of large amounts of passivation wastewater. An apparatus and method for continuously treating sodium nitrite passivation wastewater are provided, which have the advantages of being able to control the feed amount, continuously treating sodium nitrite passivation wastewater, and having a good treatment effect.

[0004] In order to achieve the above object, the present invention provides a device for continuously treating sodium nitrite passivation wastewater, the device comprising:

[0005] A premixing unit is provided with a sulfamic acid feeding port and is connected to a wastewater feeding pipeline, wherein a feeding regulating valve and a feeding flow meter are installed on the wastewater feeding pipeline, and is used to premix the sulfamic acid raw material and the sodium nitrite passivation wastewater to obtain a premixed material;

[0006] A main reaction unit, comprising a reactor connected to the premixing unit, for reacting the sodium nitrite passivated wastewater in the premixed material with the aminosulfonic acid raw material to reduce the total nitrogen content in the wastewater;

[0007] The reactor is provided with a wastewater discharge pipeline, and the wastewater discharge pipeline is connected to the premixing unit through a reflux pipe;

[0008] The pH online detection unit is used to perform pH online detection on the wastewater in the wastewater discharge pipeline to adjust the flow rate of the sodium nitrite passivated wastewater entering the premixing unit.

[0009] Another aspect of the present invention provides a method for continuously treating sodium nitrite passivation wastewater, the method using the equipment of the present invention, comprising the following steps:

[0010] 1) feeding sodium nitrite passivation wastewater with a pH of 9-11 through a wastewater feeding pipeline, and feeding sulfamic acid raw material through a sulfamic acid raw material feeding port, so that the sulfamic acid raw material and the sodium nitrite passivation wastewater are premixed in a premixing unit to obtain a premixed material;

[0011] 2) feeding the premixed material obtained in step 1) into the main reaction unit, allowing the sodium nitrite in the premixed material to react with aminosulfonic acid in the reactor to reduce the total nitrogen content in the wastewater, and the pH of the wastewater obtained by the reaction is 1.5-3;

[0012] 3) The pH of the wastewater in the wastewater discharge pipeline is detected online by a pH online detection unit to adjust the flow rate of the sodium nitrite passivated wastewater entering the premixing unit.

[0013] Through the above technical scheme, the present invention can continuously treat sodium nitrite passivation wastewater, achieve effective removal of total nitrogen, effectively reduce the wastewater treatment cycle and labor costs, and at the same time reduce the load pressure of subsequent sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of an apparatus for continuously treating sodium nitrite passivation wastewater according to one embodiment of the present invention;

[0015] Figure 2 It is a schematic diagram of equipment for treating sodium nitrite passivation wastewater in the prior art.

[0016] Description of Reference Numerals

[0017] 1 first feed pipeline; 2 second feed pipeline; 5 stirring device; 6 passivation wastewater distribution device; 7 dissolver; 8 transmission pipe; 9 transmission pump; 10 mixer; 12 reactor; 13 wastewater discharge pipeline; 14 discharge lifting pump; 15 reflux pipe; 16 online pH meter; 71 aminosulfonic acid raw material feeding port; 91 control valve; 141 discharge valve; 142 reflux valve. DETAILED DESCRIPTION

[0018] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] In the present invention, unless otherwise specified, directional words such as "up, down, left, right" used generally refer to up, down, left, right shown in the reference drawings; "inside and outside" refer to the inside and outside relative to the outline of each component itself, and directional words such as "up, down, top and bottom" used generally refer to the directions shown in the drawings or to the vertical, perpendicular or gravity direction, and are used to describe the relative positional relationships of the components.

[0021] like Figure 1 As shown, the present invention discloses a device for continuously treating sodium nitrite passivation wastewater, comprising:

[0022] A premixing unit is provided with a sulfamic acid feeding port 71 and is connected to a wastewater feeding pipeline, on which a feeding regulating valve and a feeding flow meter are installed, for premixing the sulfamic acid raw material and the sodium nitrite passivation wastewater to obtain a premixed material;

[0023] The main reaction unit includes a reactor 12 connected to the premixing unit, which is used to react the sodium nitrite passivation wastewater in the premixed material with the aminosulfonic acid raw material to reduce the total nitrogen content in the wastewater;

[0024] The reactor 12 is provided with a wastewater discharge pipeline 13, and the wastewater discharge pipeline 13 is connected to the premixing unit through a reflux pipe 15;

[0025] The pH online detection unit is used to perform pH online detection on the wastewater in the wastewater discharge pipeline 13 to adjust the flow rate of the sodium nitrite passivation wastewater entering the premixing unit.

[0026] Based on the existing problems in the pretreatment of sodium nitrite passivation wastewater, the present invention discloses a set of equipment for continuously treating sodium nitrite passivation wastewater based on pH control. On the basis of the traditional chemical cleaning base station, a dissolving drug facility and a control system are added, which can continuously treat sodium nitrite passivation wastewater, effectively remove total nitrogen, effectively reduce the wastewater treatment cycle and labor costs, and reduce the load pressure of subsequent sewage treatment. It is connected with the system to be cleaned through the wastewater feed pipeline, which can speed up the cleaning progress of the system to be cleaned, and has the characteristics of green environmental protection.

[0027] In order to facilitate the overall transportation operation and occupy a small area, in some embodiments of the present invention, the equipment for continuously treating sodium nitrite passivation wastewater of the present invention is designed as an integrated equipment, for example, the skid-mounted type in the prior art is used to combine the premixing unit, the main reaction unit and the pH online detection unit together.

[0028] In some embodiments of the present invention, Figure 1 As shown, the wastewater feed pipeline includes a first feed pipeline 1 and a second feed pipeline 2, the first feed pipeline 1 is equipped with a 1# regulating valve 1 and a first flowmeter 3, and the second feed pipeline 2 is equipped with a 2# regulating valve and a second flowmeter 4; in order to enhance the mixing effect and improve the wastewater treatment effect, in the present invention, the premixing unit includes a dissolver 7 and a mixer 10; the dissolver 7 is connected to the second feed pipeline 2 and a sulfamic acid raw material feeding port 71 is provided at the top, which is used to mix the sulfamic acid raw material with the sodium nitrite passivation wastewater to obtain a first mixture. It can be understood that the sulfamic acid raw material can be a solid raw material, and the sodium nitrite passivation wastewater is used to dissolve the solid raw material.

[0029] The mixer 10 is connected to the first feed pipeline 1 and the material outlet of the dissolver 7, and is used for performing a second mixing of the first mixture and the sodium nitrite passivation wastewater to obtain a premixed material.

[0030] In some embodiments of the present invention, Figure 1 As shown, the dissolver 7 is equipped with a stirring device 5 and a passivation wastewater distribution device 6 for distributing sodium nitrite passivation wastewater.

[0031] In some embodiments of the present invention, the aminosulfonic acid raw material is a solid raw material fed from the aminosulfonic acid raw material feeding port 71 opened at the top of the dissolver 7, and the passivation wastewater distribution device 6 is installed at the bottom of the dissolver 7 and is connected to the second feed pipeline 2 for distributing sodium nitrite passivation wastewater. The passivation wastewater distribution device 6 is configured as a liquid distributor.

[0032] In some embodiments of the present invention, based on the above disclosure, the present invention sets the mixer 10 as a pipeline mixer, and the pipeline mixer is connected to the material outlet of the dissolver 7 through the transmission pipe 8. In this way, the passivation wastewater distribution device 6, the stirring device 5, and the pipeline mixer are provided with three-stage mixing means to ensure that the aminosulfonic acid raw material and the sodium nitrite passivation wastewater are mixed evenly. The sodium nitrite passivation wastewater to be treated is distributed into the dissolver 7 through the passivation wastewater distribution device 6 at the bottom, and the solid aminosulfonic acid raw material is added from the top. The dissolver is provided with a stirrer to ensure sufficient dissolution, and the dissolver 7 is provided with a pipeline mixer after the material discharging point.

[0033] In the present invention, there is no special requirement for the liquid distributor, stirrer and pipeline mixer. The liquid distributor, stirrer and pipeline mixer commonly used in waste liquid treatment can be used in the present invention, and the present invention will not elaborate on this.

[0034] In order to achieve continuous treatment of sodium nitrite passivation wastewater and ensure uniform mixing of aminosulfonic acid raw material and sodium nitrite passivation wastewater, in some embodiments of the present invention, the wastewater discharge pipeline 13 is connected to the mixer 10 or the like through the reflux pipe 15. Figure 1 As shown, a transmission pump 9 and a control valve 91 are installed on the transmission pipe 8 in sequence, and the reflux pipe 15 is connected to the transmission pipe 8 between the mixer 10 and the control valve 91. It can be understood that the first feed pipeline 1 can also be connected to the transmission pipe 8 between the mixer 10 and the control valve 91, so that the reflux water and the incoming wastewater are fully mixed to avoid short-circuiting.

[0035] It should be noted that, in conventional wastewater pretreatment, a handheld pH meter is used at the pipeline drain to adjust the dosage of aminosulfonic acid raw material, which has problems such as large amount of operation and poor representativeness. In some embodiments of the present invention, the pH online detection unit is configured as an online pH meter 16 installed on the wastewater discharge pipeline 13. Along the flow direction of the wastewater in the wastewater discharge pipeline 13, the reflux pipe 15 is located downstream of the online pH meter 16 and a reflux valve 142 is installed on the reflux pipe 15. The present invention can realize real-time monitoring of wastewater quality with simple operation.

[0036] In some embodiments of the present invention, a discharge lift pump 14 and a discharge valve 141 are installed on the wastewater discharge pipeline 13, and an online pH meter and a reflux pipe 15 are installed between the discharge lift pump 14 and the discharge valve 141 in sequence, so that the reflux pipe 15 connects the discharge of the discharge lift pump 14 and the feed of the pipeline mixer.

[0037] The invention discloses a method for continuously treating sodium nitrite passivation wastewater, which adopts the device for continuously treating sodium nitrite passivation wastewater of the invention and comprises the following steps:

[0038] 1) feeding sodium nitrite passivation wastewater through a wastewater feeding pipeline, wherein the sodium nitrite passivation wastewater needs to satisfy a pH of 9-11, and the pH of the sodium nitrite passivation wastewater can be adjusted by an inorganic acid (such as hydrochloric acid and / or sulfuric acid). It is understood that when the pH of the sodium nitrite passivation wastewater is originally within this range, the pH does not need to be adjusted; feeding the sulfamic acid raw material through the sulfamic acid raw material feeding port 71, so that the sulfamic acid raw material and the sodium nitrite passivation wastewater are premixed in a premixing unit to obtain a premixed material;

[0039] 2) passing the premixed material obtained in step 1) into the main reaction unit, so that the sodium nitrite in the premixed material reacts with aminosulfonic acid in the reactor 12 to reduce the total nitrogen content in the wastewater, and the pH of the wastewater obtained by the reaction is 1.5-3;

[0040] 3) The pH of the wastewater in the wastewater discharge pipeline 13 is detected online through a pH online detection unit to adjust the flow rate of the sodium nitrite passivation wastewater entering the premixing unit.

[0041] In some embodiments of the present invention, the premixing in step 1) comprises:

[0042] First mixing: the sulfamic acid raw material fed from the sulfamic acid raw material feeding port 71 and the sodium nitrite passivation wastewater fed from the second feeding pipeline 2 are stirred in the dissolver 7 for first mixing to obtain a first mixture;

[0043] Second mixing: the first mixture and the sodium nitrite passivation wastewater fed from the first feed pipeline 1 are mixed in a mixer for a second time to obtain a premixed material.

[0044] In some embodiments of the present invention, in the first mixing, the aminosulfonic acid raw material includes aminosulfonic acid raw material solid and / or a solution containing aminosulfonic acid raw material, preferably the solution containing aminosulfonic acid raw material is obtained by dissolving aminosulfonic acid raw material solid by sodium nitrite passivation wastewater, and the flow rate of introducing aminosulfonic acid raw material solution is 1-5t / h. Wherein, sodium nitrite passivation wastewater is fed into the dissolver 7 through the second feed pipeline 2, dispersed into the dissolver 7 through the liquid distributor, and stirred and mixed with the aminosulfonic acid raw material by the stirrer. The present invention has no special requirements for stirring parameters, which can be adjusted according to actual working conditions, and no further description is given.

[0045] In some embodiments of the present invention, in the first mixing, sodium nitrite passivation wastewater is first fed into the dissolver 7 through the second feed pipeline 2, and then aminosulfonic acid raw material is added to the passivation wastewater through the aminosulfonic acid raw material feeding port 71 for reaction.

[0046] In some embodiments of the present invention, the sodium nitrite passivation wastewater fed through the wastewater feed pipeline in step 1) has a pH of 9-10. Within this range, it is more conducive to the aminosulfonic acid raw material to react preferentially with sodium nitrite, the sodium nitrite removal effect is better, and the amount of sodium hydroxide added can be reduced, thereby reducing the cost of the reagent.

[0047] In the present invention, theoretically, when the mass concentration of sulfamic acid in the reactor 12 is 1.4%, sulfamic acid and sodium nitrite can react almost completely to generate nitrogen. Therefore, the mass concentration of sulfamic acid in the dissolver 7 affects the flow rate of the first feed pipeline 1. In some embodiments of the present invention, the mass concentration of sulfamic acid in the first mixture obtained by the first mixing is 10-25%, preferably 10-20%.

[0048] On the basis of the above disclosure, the present invention provides a method for adjusting the treatment effect of sodium nitrite passivation wastewater by controlling the amount of aminosulfonic acid added. Compared with the traditional method of adjusting the treatment effect of sodium nitrite passivation wastewater by controlling the amount of aminosulfonic acid added, the treatment idea of ​​the present invention is "maintaining the amount of aminosulfonic acid added unchanged, controlling the pollutant load of sodium nitrite to meet the treatment effect", and setting a flow meter to guide the adjustment of the amount of sodium nitrite passivation wastewater, simplifying the operation while also meeting the requirements of refined operation. In some embodiments of the present invention, the flow rate of the first feed line 1: the flow rate of the second feed line 2 is 5-17:1. In this way, the flow rate of the second feed line 2 and the amount of aminosulfonic acid added are kept as stable as possible, and are not adjusted. Instead, the flow rate of the first feed line 1 is mainly adjusted to achieve the adjustment of the total amount of sodium nitrite passivation wastewater, and finally achieve the basic balance of the reaction.

[0049] In some embodiments of the present invention, the sodium nitrite content in the sodium nitrite passivation wastewater is 1000-3000 mg / L. The sodium nitrite passivation wastewater of the present invention is obtained after alkali washing, acid washing, rinsing and then passivation treatment, and except for sodium nitrite, other impurities can be ignored.

[0050] In some embodiments of the present invention, the passivation conditions for obtaining sodium nitrite passivation wastewater are: 1wt%-3wt% sodium nitrite passivator, temperature of 50-60°C, time of 6-12h, for example, 1wt% sodium nitrite can be used to passivate system pipelines (such as system pipelines or product tanks in petrochemical, steel and other industry devices), and after the passivation is completed, the wastewater is pretreated by the equipment for continuously treating sodium nitrite passivation wastewater of the present invention.

[0051] In some embodiments of the present invention, the pH of the premix is ​​adjusted to 9-11, preferably 9-10.

[0052] In some embodiments of the present invention, in step 2), the reaction conditions include: temperature 40-60°C, normal pressure, reflux ratio 1-2, reaction time 20-40min, preferably 20-30min. It is understood that the aminosulfonic acid raw material is easily soluble in water and the skid-mounted equipment of the present invention is convenient for transportation and generally has a small volume, for example, 1-2m 3 In addition, the pipeline distance between the dissolver 7 and the reactor 12 is also very short, so the contact time before entering the reactor 12 is very short, which has little impact on this solution and will not be described in detail in the present invention.

[0053] In some embodiments of the present invention, the residence time of the main reaction unit can be 20-40 min, preferably 20-30 min, by adjusting the flow rate of the first feed pipeline 1 and / or the reflux rate of the reflux pipe 15. At the same time, the reflux also serves to fully contact the aminosulfonic acid raw material and sodium nitrite to accelerate the reaction. When the amount of wastewater is large, increasing the reflux ratio can increase the residence time without increasing the volume of the reactor, and at the same time can fully mix to ensure the stability of the pH of the discharged wastewater.

[0054] The inventor of the present invention found in the research process that the residence time of the reaction is less than 20min, the reaction occurs incompletely, the sodium nitrite treatment effect is poor, the residence time of the reaction is greater than 40min, the manpower, material and financial resources invested are large, and there is no economy and efficiency. According to the present invention, the reaction residence time can be determined by adjusting the flow and reflux ratio of the first feed line 1. Preferably, the flow (first feed line flow+second feed line flow) of the sodium nitrite passivation wastewater introduced into the equipment of the present invention is 30-90t / h. In the present invention, the reflux ratio is the ratio of the weight of the wastewater entering the reflux pipe 15 to the total weight of the sodium nitrite passivation wastewater introduced into the water.

[0055] In some embodiments of the present invention, the pH of the wastewater obtained by the reaction in step 2) is 2-3. In order to ensure the stability of the total nitrogen removal effect, the dosage of the aminosulfonic acid raw material needs to be strictly controlled. However, during industrial operation, the amount of wastewater is large, the components are complex, and there is no precise control of the dosage of the aminosulfonic acid raw material on site. The pH is used as the basis for controlling the dosage of the aminosulfonic acid raw material for convenient operation on site to improve the treatment efficiency. The inventors of the present invention have found that when the pH of the wastewater is 2-3, the content of total nitrogen in the wastewater is <500mg / L, which meets the water quality requirements of the industrial sewage treatment plant, but if the pH continues to decrease, it may cause excessive addition of aminosulfonic acid, so that the total nitrogen concentration in the wastewater increases and affects the treatment effect. Therefore, keeping the wastewater pH 2-3 can facilitate operation, reduce pollutant concentration fluctuations, and reduce treatment costs.

[0056] Taking into account the corrosion problem of the external pipeline caused by wastewater discharge and the limited acid-base adjustment capacity of the downstream sewage treatment plant, in some embodiments of the present invention, the pH of the wastewater obtained by the reaction in step 2) is adjusted to 6-9 with an inorganic base (such as 20wt% sodium hydroxide aqueous solution) before discharge.

[0057] Regarding the regulation of step 3), specifically, in the present invention, the flow rate ratio of the first feed pipe and the second feed pipe is 5-17, and the reflux ratio of the reaction in the reactor is controlled to be 1-2; when pH>3 (indicating that the amount of aminosulfonic acid raw material added is small, that is, the amount of sodium nitrite wastewater is large), the flow rate of the first feed line 1 should be reduced at this time, that is, the flow rate of the first feed line and the flow rate of the second feed line should be controlled small, and the reflux ratio of the reaction in the corresponding reactor increases. At the same time, in order to maintain the stability of the liquid level in the reactor and reduce the amount of unqualified sewage, the corresponding external discharge volume is also reduced synchronously. Similarly, when pH<1.5 (indicating that the amount of aminosulfonic acid raw material added is excessive, that is, the amount of sodium nitrite wastewater is small), the flow rate of the first feed line 1 should be increased at this time, and at the same time, under the premise of ensuring that the liquid level does not overflow, the flow rate of the reflux pipe 15 should be increased, the external discharge volume (the amount of unqualified sewage) should be reduced, and the reflux ratio of the reaction in the reactor should be maintained as much as possible. 1-2.

[0058] The method provided by the present invention is a method for continuously treating sodium nitrite passivation wastewater suitable for industrial application, which is obviously different from the intermittent treatment currently only applied in laboratories. Preferably, the total introduction flow rate of the sodium nitrite passivation wastewater is 30-90 t / h, and the total introduction flow rate of the solution containing aminosulfonic acid raw material is 1-5 t / h.

[0059] The effects of the present invention will be described below by way of examples, but the present invention is not limited thereto.

[0060] The following examples are Figure 1 Shown by Figure 1 The equipment for continuous treatment of sodium nitrite passivation wastewater is shown for pretreatment, and the equipment is integrated in the form of a skid-mounted module in the prior art, such as Figure 1 As shown, the equipment for continuously treating sodium nitrite passivation wastewater of the present invention comprises a dissolver 7, a pipeline mixer (mixer 10) and a reactor 12 which are sequentially connected along the material flow direction, wherein the top opening of the dissolver 7 is formed as a sulfamic acid raw material feeding port 71, a stirrer and a liquid distributor are installed in the dissolver, and the liquid distributor is installed at the bottom of the dissolver 7 and is connected to the second feed pipeline 2; the dissolver 7 is connected to the reactor through a transmission pipe 8, and a transmission pump 9, a control valve 91 and a mixer 10 are sequentially installed along the material flow direction. On the transmission pipe 8, the second feed line 2 is connected to the transmission pipe 8 between the mixer 10 and the control valve 91, the first feed line 1 is equipped with a 1# regulating valve 1 and a first flow meter 3, and the second feed line 2 is equipped with a 2# regulating valve and a second flow meter 4; the reactor 12 is connected to the wastewater discharge line 13, and the wastewater discharge line 13 is sequentially equipped with a discharge lift pump 14, an online pH meter 16 and a discharge valve 141, and the reflux pipe 15 is equipped with a reflux valve 142 and the two ends are respectively connected to the feed of the mixer 10 and the discharge of the reactor. The dissolver volume in the following embodiments is the same, all 2m 3 .

[0061] The method comprises: feeding sodium nitrite passivation wastewater into a dissolver 7 through a second feeding pipeline 2, feeding aminosulfonic acid raw material through an aminosulfonic acid raw material feeding port 71, and feeding sodium nitrite passivation wastewater into a pipeline mixer through a first feeding pipeline 1.

[0062] In the following examples and comparative examples, the total nitrogen parameter was measured by online digestion gas phase molecular absorption spectroscopy, and the pH was measured by glass electrode method. On this basis, the total nitrogen removal rate was calculated by the following formula.

[0063] Total nitrogen removal rate (%) = [(initial total nitrogen concentration - total nitrogen concentration after treatment) / initial total nitrogen concentration] × 100%.

[0064] Example 1

[0065] The ultra-high pressure steam pipeline of the ethylene cracking unit was passivated and cleaned using a 1wt% sodium nitrite solution at 60°C for 12 hours, generating about 180m3 of sodium nitrite passivation wastewater. 3 , with a total nitrogen concentration of 1745 mg / L and a pH of 10.78.

[0066] pass Figure 1 The equipment for continuous treatment of sodium nitrite passivation wastewater is shown for pretreatment:

[0067] The sulfamic acid raw material fed into the dissolver 7 is solid sulfamic acid, the sodium nitrite passivation wastewater feed flow rate of the second feed pipeline 2 is 5 t / h, and the first mixture containing sulfamic acid with a mass concentration of 20% is dissolved;

[0068] The first mixture is passed into a pipeline mixer, and sodium nitrite passivation wastewater is fed into the pipeline mixer through a first feed pipeline 1, with a feed flow rate of 70 t / h, to form a premixed material in the pipeline mixer.

[0069] The pH of the wastewater obtained by the reaction in the reactor is 1.5-3, wherein the reaction temperature is 40-60° C., the reaction pressure is normal pressure, the reflux ratio is 1, and the reaction time is 24 minutes.

[0070] The wastewater in the wastewater discharge pipeline 13 is discharged after adjusting the pH to 6-9 with a 20 wt % sodium hydroxide aqueous solution.

[0071] During the treatment process, when the online pH meter detects that the pH is greater than 3, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 is adjusted to 65 t / h, the reflux rate is still maintained at 75 t / h, and the discharge rate of the discharge lift pump 14 is simultaneously adjusted to 70 t / h to maintain the stability of the reactor liquid level. The online pH meter reading is observed. If the pH is still greater than 3, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 and the amount of discharged wastewater are further reduced until the pH is 1.5-3;

[0072] During the treatment process, when the online pH meter detects that the pH is less than 1.5, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 is adjusted to 75t / h, the reflux rate is adjusted to 80t / h, and the discharge volume of the discharge lift pump 14 is simultaneously adjusted to 80t / h to maintain the stability of the cleaning tank liquid level. Observe the reading of the online pH meter. If the pH is still less than 1.5, continue to increase the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 and the amount of discharged wastewater until the pH is 1.5-3.

[0073] The results are shown in Table 1:

[0074] Table 1:

[0075]

[0076] After treatment, the total nitrogen removal rate was 84.0%-95.7%.

[0077] Example 2

[0078] A 1wt% sodium nitrite solution was used to passivate and clean the aromatics extraction unit C-201 / D-201. The passivation was carried out at 60°C for 12 hours to obtain 79m3 of sodium nitrite passivation wastewater. 3 , total nitrogen concentration was 1565 mg / L, and pH was 10.81.

[0079] pass Figure 1 The equipment for continuous treatment of sodium nitrite passivation wastewater is shown for pretreatment:

[0080] The sulfamic acid raw material fed into the dissolver 7 is a solid sulfamic acid raw material, and the sodium nitrite passivation wastewater feed flow rate of the second feed pipeline 2 is 3 t / h, and the first mixture containing sulfamic acid with a mass concentration of 20% is dissolved;

[0081] The first mixture is introduced into a pipeline mixer, and sodium nitrite passivation wastewater is fed into the pipeline mixer through a first feed pipeline 1, with a feed flow rate of 42 t / h, to form a premixed material aminosulfonic acid raw material in the pipeline mixer.

[0082] The pH of the wastewater obtained by the reaction in the reactor is 2-3, wherein the reaction temperature is 40-60° C., the reaction pressure is normal pressure, the reflux ratio is 1, and the reaction time is 40 min.

[0083] The wastewater in the wastewater discharge pipeline 13 is discharged after adjusting the pH to 6-9 with a 20 wt % sodium hydroxide aqueous solution.

[0084] During the treatment process, when the online pH meter detects that the pH is greater than 3, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 is adjusted to 37 t / h, the reflux volume is still maintained at 45 t / h, and the discharge volume of the discharge lift pump 14 is simultaneously adjusted to 40 t / h to maintain the stability of the cleaning tank liquid level. The online pH meter reading is observed. If the pH is still greater than 3, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 and the amount of discharged wastewater are further reduced until the pH is 2-3; or

[0085] During the treatment process, when the online pH meter detects that the pH is less than 2, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 is adjusted to 47t / h, the reflux rate is adjusted to 50t / h, and the discharge volume of the discharge lift pump 14 is adjusted to 50t / h to maintain the stability of the cleaning tank liquid level. Observe the reading of the online pH meter. If the pH is still less than 2, continue to increase the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 and the amount of discharged wastewater until the pH is 2-3.

[0086] The results are shown in Table 2:

[0087] Table 2:

[0088]

[0089] After treatment, the total nitrogen removal rate was 93.3%-95.0%.

[0090] Example 3

[0091] 1wt% sodium nitrite solution was used to passivate and clean the cracking gasoline hydrogenation unit C-120. The passivation was carried out at 60℃ for 12 hours to obtain 224m3 of sodium nitrite passivation wastewater. 3 , total nitrogen concentration was 2210 mg / L, and pH was 9.96.

[0092] pass Figure 1 The equipment for continuous treatment of sodium nitrite passivation wastewater is shown for pretreatment:

[0093] The sulfamic acid raw material fed into the dissolver 7 is a solid sulfamic acid raw material, the sodium nitrite passivation wastewater feed flow rate of the second feed pipeline 2 is 5 t / h, and the first mixture containing sulfamic acid with a mass concentration of 25% is dissolved;

[0094] The first mixture is passed into a pipeline mixer, and sodium nitrite passivation wastewater is fed into the pipeline mixer through a first feed pipeline 1, with a feed flow rate of 85 t / h, to form a premixed material aminosulfonic acid raw material in the pipeline mixer.

[0095] The pH of the wastewater obtained by the reaction in the reactor is 1.5-3, wherein the reaction temperature is 40-60° C., the reaction pressure is normal pressure, the reflux ratio is 1, and the reaction time is 20 min.

[0096] The wastewater in the wastewater discharge pipeline 13 is discharged after adjusting the pH to 6-9 with a 20 wt % sodium hydroxide aqueous solution.

[0097] During the treatment process, when the online pH meter detects that the pH is greater than 3, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 is adjusted to 80 t / h, the reflux rate is still maintained at 90 t / h, and the discharge rate of the discharge lift pump 14 is simultaneously adjusted to 85 t / h to maintain the stability of the cleaning tank liquid level. The online pH meter reading is observed. If the pH is still greater than 3, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 and the amount of discharged wastewater are further reduced until the pH is 1.5-3;

[0098] During the treatment process, when the online pH meter detects that the pH is less than 1.5, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 is adjusted to 75t / h, the reflux rate is adjusted to 95t / h, and the discharge volume of the discharge lift pump 14 is simultaneously adjusted to 95t / h to maintain the stability of the cleaning tank liquid level. Observe the reading of the online pH meter. If the pH is still less than 1.5, continue to increase the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 and the amount of discharged wastewater until the pH is 1.5-3.

[0099] The results are shown in Table 3:

[0100] Table 3:

[0101]

[0102] After treatment, the total nitrogen removal rate was 82.1%-89.5%.

[0103] Example 4

[0104] Different from Example 1, the first feed pipeline 1 is not provided, and the cleaned wastewater portion is fed through the second feed pipeline 2, and the remaining portion directly enters the equipment for continuously treating sodium nitrite passivation wastewater of the present invention from the top of the reactor 12.

[0105] 1wt% sodium nitrite solution was used to passivate and clean the EO spherical tank of the EOEG device. The passivation was carried out at 60℃ for 12 hours to obtain 55m3 of sodium nitrite passivation wastewater. 3 , total nitrogen concentration 1500 mg / L, pH 10.72.

[0106] The aminosulfonic acid raw material is fed into the dissolver 7, wherein the aminosulfonic acid raw material is in solid form, the sodium nitrite passivation wastewater feed flow rate of the second feed pipeline 2 is 4 t / h, and the first mixture containing the aminosulfonic acid mass concentration of 10% is dissolved, and the dissolver effluent is further mixed by the pipeline mixer and enters the reactor. The water inlet amount at the top of the reactor 12 is about 26 t / h, and the wastewater pH value obtained by the reaction in the reactor is 2-3, wherein the reaction temperature is 40-60°C, the reaction pressure is normal pressure, the reflux ratio is 1, and the reaction time is 60 min.

[0107] The wastewater in the wastewater discharge pipeline 13 is discharged after adjusting the pH to 6-9 with a 20 wt % sodium hydroxide aqueous solution.

[0108] During the treatment process, when the online pH meter detects that the pH is greater than 3, the amount of aminosulfonic acid raw material is increased;

[0109] During the treatment process, when the online pH meter detects that the pH is less than 2, the amount of aminosulfonic acid raw material added is reduced.

[0110] The results are shown in Table 4:

[0111]

[0112] After the treatment, the total nitrogen removal rate was 85.9%-92.4%. However, when the pH fluctuates, the amount of aminosulfonic acid raw material added needs to be adjusted, and the operation is more difficult to control than in Examples 1-3. At the same time, since part of the sodium nitrite passivation wastewater is added from the top of the reactor, there is a risk of uneven mixing. It is necessary to control the treatment amount and increase the reaction residence time to ensure the treatment effect, which prolongs the operation time and increases the workload (for example, in Example 2, 79m 3 Wastewater treatment: about 1.7h; Example 4, treatment of 55m 3 Wastewater takes about 1.8 hours, and the time cost increases).

[0113] Example 5

[0114] Different from Example 1, the mass concentration of aminosulfonic acid in the first mixture is controlled to be 4%, the flow rate of the first feed pipeline 1 is 30 t / h, and the flow rate of the second feed pipeline 2 is 10 t / h (the flow ratio of the first feed pipeline 1 to the second feed pipeline 2 is 3:1).

[0115] The condensate system of the aromatics extraction unit was passivated and cleaned using a 1wt% sodium nitrite solution at 60°C for 12 hours to obtain 50m3 of sodium nitrite passivation wastewater. 3 , total nitrogen concentration is 1857 mg / L, pH is 10.17. Figure 1The equipment for continuous treatment of sodium nitrite passivation wastewater is shown for pretreatment, and the mass concentration of aminosulfonic acid in the first mixture is initially controlled to be about 4%, the flow rate of the first feed line 1 is 30 t / h, and the flow rate of the second feed line 2 is 10 t / h. The pH of the wastewater obtained by the reaction in the reactor is 1.5-3, wherein the reaction temperature is 40-60°C, the reaction pressure is normal pressure, the reflux ratio is 1, and the reaction time is 45 min.

[0116] During the initial treatment process, it was detected that the pH of the wastewater was greater than 3. According to the control idea, the amount of sodium nitrite passivation wastewater in the first feed pipeline 1 needs to be reduced. However, considering that the equipment is equipped with a passivation wastewater distribution device 6, a stirring device 5, and a pipeline mixer, the three-stage mixing means can ensure that the aminosulfonic acid raw material and the sodium nitrite passivation wastewater are mixed evenly, and the flow rate of the second feed pipeline 2 is 10t / h, which will cause the dissolver 7 to have a high risk of bubbling (the dissolver volume in the embodiment is the same, both are 2m 3 ), so we tried to adjust the amount of aminosulfonic acid added and the flow rate of the second feed line 2 to increase the mass concentration of aminosulfonic acid in the first mixture to about 10% and adjust the flow rate of the second feed line 2 to 4 t / h.

[0117] The wastewater in the wastewater discharge pipeline 13 is discharged after adjusting the pH to 6-9 with a 20 wt % sodium hydroxide aqueous solution.

[0118] The results are shown in Table 5:

[0119]

[0120]

[0121] After treatment, the total nitrogen removal rate was 82.5%-84.9%.

[0122] Comparative Example 1

[0123] The condensate system of the cracked gasoline hydrogenation unit was passivated and cleaned using a 1wt% sodium nitrite solution at 60°C for 12 hours to obtain 98m3 of sodium nitrite passivation wastewater. 3 , total nitrogen concentration was 1857 mg / L, and pH was 9.99.

[0124] pass Figure 2 The equipment for treating sodium nitrite passivation wastewater in the prior art shown is pre-treated:

[0125] The aminosulfonic acid raw material is directly added to the cleaning tank, wherein the aminosulfonic acid raw material is in solid form, and the feeding amount of the cleaning tank is 45t / h. The aminosulfonic acid raw material and the passivation wastewater are mixed evenly by reflux through the lifting pump, and the amount of aminosulfonic acid raw material added is adjusted by the reading of a handheld pH meter at the drainage point of the external discharge pipeline, and the total nitrogen concentration is measured by sampling during the process. The wastewater obtained by the reaction is adjusted to pH 6-9 with a 20wt% sodium hydroxide aqueous solution before being discharged.

[0126] The pH of the wastewater obtained by the reaction in the cleaning tank is 2-3, wherein the reaction temperature is 40-60°C, the reaction pressure is normal pressure, the reflux ratio is 1, and the reaction time is 40 minutes.

[0127] The results are shown in Table 4:

[0128]

[0129] After the treatment, the total nitrogen removal rate was 59.8%-72.7%. At the same time, water samples were collected at the leaching point for chemical analysis. The problem of unrepresentative samples existed, and there was a deviation in guiding the dosage of aminosulfonic acid raw materials. The treatment effect was general.

[0130] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various specific technical features in any appropriate manner. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations. However, these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A device for continuously treating sodium nitrite passivation wastewater, characterized in that: The device comprises: A premixing unit is provided with a sulfamic acid feeding port (71) and is connected to a wastewater feeding pipeline, wherein a feeding regulating valve and a feeding flow meter are installed on the wastewater feeding pipeline, and are used to premix the sulfamic acid raw material and the sodium nitrite passivation wastewater to obtain a premixed material; A main reaction unit, comprising a reactor (12) connected to the premixing unit, for reacting the sodium nitrite passivated wastewater in the premixed material with the aminosulfonic acid raw material to reduce the total nitrogen content in the wastewater; The reactor (12) is provided with a wastewater discharge pipeline (13), and the wastewater discharge pipeline (13) is connected to the premixing unit through a reflux pipe (15); The pH online detection unit is used to perform online pH detection on the wastewater in the wastewater discharge pipeline (13) so as to adjust the flow rate of the sodium nitrite passivated wastewater entering the premixing unit according to the pH.

2. The equipment for continuously treating sodium nitrite passivation wastewater according to claim 1, characterized in that, The wastewater feed pipeline comprises a first feed pipeline (1) and a second feed pipeline (2); the premixing unit comprises a dissolver (7) and a mixer (10); The dissolver (7) is connected to the second feed pipeline (2) and the top opening is formed as the aminosulfonic acid raw material feeding port (71), which is used to perform a first mixing of the aminosulfonic acid raw material and the sodium nitrite passivation wastewater to obtain a first mixture; The mixer (10) is connected to the first feed pipeline (1) and the material outlet of the dissolver (7), and is used to perform a second mixing of the first mixture and the sodium nitrite passivation wastewater to obtain the premixed material; and / or The pH online detection unit is configured as an online pH meter (16) installed on the wastewater discharge pipeline (13), and along the flow direction of the wastewater in the wastewater discharge pipeline (13), the reflux pipe (15) is located downstream of the online pH meter (16).

3. The equipment for continuously treating sodium nitrite passivation wastewater according to claim 2, characterized in that, The dissolver (7) is provided with a stirring device (5) and a passivation wastewater distribution device (6), and the passivation wastewater distribution device (6) is used to distribute the sodium nitrite passivation wastewater; Preferably, the passivation wastewater distribution device (6) is installed at the bottom of the dissolver (7) and is connected to the second feed pipeline (2).

4. The equipment for continuously treating sodium nitrite passivation wastewater according to claim 2 or 3, characterized in that, The mixer (10) is connected to the material outlet of the dissolver (7) via a transmission pipe (8), and the mixer (10) is configured as a pipeline mixer installed on the transmission pipe (8); and / or The wastewater discharge pipeline (13) is connected to the mixer (10) via a reflux pipe (15).

5. A method for continuously treating sodium nitrite passivation wastewater, characterized in that: The method uses the device described in any one of claims 1 to 4, comprising the following steps: 1) feeding sodium nitrite passivation wastewater with a pH of 9-11 through a wastewater feeding pipeline, feeding sulfamic acid raw material through a sulfamic acid feeding port (71), so that the sulfamic acid raw material and the sodium nitrite passivation wastewater are premixed in a premixing unit to obtain a premixed material; 2) feeding the premixed material obtained in step 1) into the main reaction unit, allowing the sodium nitrite in the premixed material to react with aminosulfonic acid in the reactor (12) to reduce the total nitrogen content in the wastewater, and the pH of the wastewater obtained by the reaction is 1.5-3; 3) The pH of the wastewater in the wastewater discharge pipeline (13) is detected online by a pH online detection unit to adjust the flow rate of the sodium nitrite passivated wastewater entering the premixing unit.

6. The method according to claim 5, wherein: The premixing in step 1) comprises: First mixing: the aminosulfonic acid raw material and the sodium nitrite passivation wastewater fed from the second feed pipeline (2) are first mixed in a dissolver (7) to obtain a first mixture; Second mixing: The first mixture and the sodium nitrite passivation wastewater fed from the first feed pipeline (1) are mixed in a mixer for a second time to obtain a premixed material.

7. The method according to claim 6, wherein: The mass concentration of sulfamic acid in the first mixture is 10-25%, preferably 10-20%; and / or The ratio of the flow rate of the first feed line (1) to the flow rate of the second feed line (2) is 5-17:

1.

8. The method according to any one of claims 5 to 7, wherein: In step 2), the reaction conditions include: temperature 40-60°C, normal pressure, reflux ratio 1-2, reaction time 20-40min, preferably 20-30min; and / or In step 2), the pH of the wastewater obtained by the reaction is 2-3.

9. The method according to any one of claims 5 to 8, wherein: In step 3), when the online pH meter detects that the pH is greater than 3, the flow rate of the first feed pipe (1) is reduced until the online pH meter detects that the pH is 1.5-3; or In step 3), when the online pH meter detects that the pH is less than 1.5, the flow rate of the first feed pipe (1) is increased until it is 1.5-3.

10. The method according to any one of claims 5 to 9, wherein: The sodium nitrite content in the sodium nitrite passivation wastewater is 1000-3000 mg / L; and / or The passivation conditions for obtaining sodium nitrite passivation wastewater are: 1wt%-3wt% of sodium nitrite passivator, temperature of 50-60°C, and time of 6-12h.

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