CN105862048A - Chemical cleaning method - Google Patents
Chemical cleaning method Download PDFInfo
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- CN105862048A CN105862048A CN201510028791.3A CN201510028791A CN105862048A CN 105862048 A CN105862048 A CN 105862048A CN 201510028791 A CN201510028791 A CN 201510028791A CN 105862048 A CN105862048 A CN 105862048A
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- acid
- cleaning method
- citric acid
- chemical cleaning
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Abstract
The invention relates to a chemical cleaning method. The method comprises following steps: in predetermined time intervals, adding citric acid and a corrosion inhibitor with different acid mass fractions, performing circular cleaning for the predetermined time length; adding a desalinized water solution containing a deoxygenation agent for topemptying acid waste liquid according to a predetermined flow velocity; and adding a sodium nitrite solution for topemptying the acid waste liquid and performing passivation treatment. The chemical cleaning method has good cleaning effect, is capable of preventing rust returning phenomenon on the surface of active metal as well as saving a cleaning solution, and is more environmentally friendly and economic.
Description
Technical field
The present invention relates to pipeline flush field, particularly relate to a kind of combination PIG clean chemical cleaning method.
Background technology
Along with technology development and the needs of industry, the technology application of physical cleaning engineering is more and more.Wherein, a kind of technology that PIG takes out stains with physical means when cleaning, it is mainly used in inner surface of pipeline rust cleaning, scale removal, is dehydrated, is dried and applies, is prevention and the good technique removing pipeline scale.The elastomer of the shape such as bullet that the PIG special polyurethane material of employing is made, when using PIG to clean, under the promotion of pressure medium, PIG runs in pipe, make PIG and inner surface of pipeline squeezed tight, under the effect of frictional force by pipeline in fouling, deposit remove.Though the large-scale fouling in the removable pipeline of PIG cleaning method, but cannot thoroughly remove for the oxide layer that the granular deposit in pipeline, particularly pipe surface are fine and close.So, need a kind of chemical cleaning method badly to combine PIG physical cleaning method, thus reach more preferable cleaning performance.
Summary of the invention
It is an object of the invention to provide a kind of chemical cleaning method, its cleaning performance is good, prevents active metal surface from returning rust, saves cleanout fluid, more environmentally-friendly economy.
For achieving the above object, the chemical cleaning method of the present invention, comprise the following steps:
In predetermined time interval, add citric acid and the corrosion inhibiter of different acid mass fraction, and carry out wash cycles scheduled duration；
The desalination solution containing oxygen scavenger is added with top row acid waste liquid with predetermined flow velocity；And
Add sodium nitrite solution and with top row acid waste liquid and carry out Passivation Treatment.
Compared with prior art, the chemical cleaning method of the present invention uses citric acid to divide gradient to put into so that save washing liquid in acid cleaning process, and cleaning performance is obvious；And pass through the inhibitory action of Secondary floated rust and follow-up Passivation Treatment, make active metal surface avoid returning the time of the fouling of getting rusty becoming rusty and slowing down pipeline.
It is preferred that the citric acid adding different sour mass fractions in predetermined time interval includes:
The citric acid that acid mass fraction is 3.0%～2.5% is added when acid cleaning process starts；
After acid cleaning process starts first adds the citric acid that acid mass fraction is 2.5%～2.0% for three hours；
After acid cleaning process starts second adds the citric acid that acid mass fraction is 2.0%～1.5% for three hours；
After acid cleaning process starts the 3rd adds the citric acid that acid mass fraction is 1.5%～1.0% for three hours；
Last hour before acid cleaning process terminates adds the citric acid that acid mass fraction is 1.0%～0.5%.
It is preferred that also include after adding citric acid: addition ammonia the pH value regulating acid solution are 3～4.
It is preferred that also include total iron concentration that timing detects in solution in acid cleaning process.
It is preferred that also include stopping wash cycles, static soak scheduled duration in acid cleaning process.
It is preferred that the pH value of described desalination solution is 8.5～10, the addition flow velocity of described desalination solution is 8L/min～12L/min.
It is preferred that the pH value of described sodium nitrite solution is 9.5～11.
It is preferred that during sodium nitrite solution top row acid waste liquid, also include that timing detects the sour mass fraction at pipeline outlet and total iron concentration.
It is preferred that with sodium nitrite solution top row acid waste liquid time a length of 8～12 hours, described passivation time a length of 20～30 hours.
It is preferred that temperature when carrying out pickling with citric acid controls at 70～100 DEG C.
Detailed description of the invention
Below in conjunction with embodiment, the chemical cleaning method of the present invention is described further, but is not so limited the present invention.
The chemical cleaning method of the present invention is applicable to combine with pipeline PIG physical cleaning method, it is not limited to this, its fouling being equally applicable to any metallic conduit is cleaned, and has cleaning performance good, saves the benefit of cleanout fluid.
First embodiment of the present invention comprises the following steps:
The first, acid pickling step: add citric acid and the corrosion inhibiter of different acid mass fraction in predetermined time interval, and carry out wash cycles scheduled duration；
The second, Secondary floated rust suppression processes: add the desalination solution containing oxygen scavenger with top row acid waste liquid with predetermined flow velocity；And
3rd, Passivation Treatment: add sodium nitrite solution and with top row acid waste liquid and carry out Passivation Treatment.
In acid pickling step, the present invention uses citric acid to be main Acidwash solution, and citric acid is complexing cleaning, becomes the quantity of slag few, less to austenite stainless steel corrosion.In the control of citric acid, the present embodiment uses the mode of gradient dosing, adds the citric acid of different acid mass fraction in different time intervals at entrance, to reach optimal cleaning performance, and saves the use of citric acid.Specifically, experiment proves that, the gradient of the citric acid of the present invention adds and the preferred embodiment of making time is as follows:
The citric acid that acid mass fraction is 3.0%～2.5% is added when acid cleaning process starts；
After acid cleaning process starts first adds the citric acid that acid mass fraction is 2.5%～2.0% for three hours；
After acid cleaning process starts second adds the citric acid that acid mass fraction is 2.0%～1.5% for three hours；
After acid cleaning process starts the 3rd adds the citric acid that acid mass fraction is 1.5%～1.0% for three hours；
Last hour before acid cleaning process terminates adds the citric acid that acid mass fraction is 1.0%～0.5%.
As a more preferably embodiment, the Fructus Citri Limoniae acid cleaning process of the present embodiment is 10 hours, and sour mass fraction and the making time of the citric acid every time put into show such as table 1 below:
Table 1
| Citric acid mass fraction (%) | Making time interval (h) |
| 3.0 | At the beginning of cleaning |
| 2.5 | 3.0 |
| 1.5 | 3.0 |
| 1.0 | 3.0 |
| 0.5 | 1.0 |
The gradient of the mass fraction of classifying rationally citric acid of the present invention adds and joining day interval, and to ensure the phase after pickling, the sour mass fraction of pipe end is slightly above the sour mass fraction of porch, thus preferably cleans whole pipeline, saves pickle.
It is preferred that also include total iron concentration that timing detects in solution in acid cleaning process.Specifically, total iron concentration is detected respectively at entrance and at pipe end.All put at entrance due to citric acid solution each time, so the total iron concentration at entrance is minimum.In one embodiment, at the beginning of cleaning, at entrance, total iron concentration of detection is 3752mg/L, along with being gradually added into of citric acid, when detecting that the total iron concentration at entrance is 240mg/L, the metal surface rust deposite of porch eliminates substantially, continue to clean, when total iron concentration pipeline exit being detected is dropped to 2352mg/L by 3752mg/L, show that higher concentration iron is got rid of in pipeline.For making pickle and rust deposite be fully contacted reaction, the present embodiment also includes that stopping circulating pump cleaning, and closes outlet drain valve, static soak 6 hours.
As a preferred embodiment, while adding citric acid, add Lan-826 corrosion inhibiter, and add ammonia thus regulate pH value 3～4, preferably 3.5.
As a preferred embodiment, in process of making up a prescription before being carried out and acid cleaning process, need strict temperature control at 70～100 DEG C.Such as, carrying out making up a prescription of citric acid and water under 70 DEG C of environment, cleanout fluid flows out through over cleaning pump, is 95 DEG C through the temperature of over-heat-exchanger.Under this temperature environment, the cleaning performance of citric acid is optimal, and the rust dissolved will not separate out from cleanout fluid and be deposited on equipment and pipeline inwall.
In the process of the Secondary floated rust of second step, this desalination solution contains oxygen scavenger, and pH value controls 8.5～10, and preferably 9, the addition flow velocity of desalination solution is 8L/min～12L/min, and this top row process is about 1 hour.Use the step of alkalescence desalted water top row pickle, the active metal surface Secondary floated rust after overpickling can be avoided.
Subsequently, for preventing active metal from returning rust further, present invention additionally comprises and be passivated with pH value sodium nitrite solution between 9.5～11.Specifically, due to above-mentioned pickle outer row not yet, continue the most in this step with sodium nitrite solution top row pickle.As a preferred embodiment, during discharge pickle, also include that timing detects the sour mass fraction at pipeline outlet and total iron concentration, discharge can be stopped after reaching predetermined value.Such as, the continued emissions time of sodium nitrite solution is 8～12 hours, and 10 hours more preferably, now closes outlet drain valve, static soak 20～30 hours, as 24 hours are passivated, thus forms the protecting film of densification at inner-walls of duct.
In sum, the chemical cleaning method of the present invention uses citric acid to divide gradient to put into so that save washing liquid in acid cleaning process, and cleaning performance is obvious；And pass through the inhibitory action of Secondary floated rust and follow-up Passivation Treatment, make active metal surface avoid returning the time of the fouling of getting rusty becoming rusty and slowing down pipeline.
The above disclosed presently preferred embodiments of the present invention that is only, certainly can not limit the interest field of the present invention, the equivalent variations therefore made according to scope of the present invention patent with this, still belong to the scope that the present invention is contained.
Claims (10)
1. a chemical cleaning method, comprises the following steps:
In predetermined time interval, add citric acid and the corrosion inhibiter of different acid mass fraction, and carry out wash cycles scheduled duration；
The desalination solution containing oxygen scavenger is added with top row acid waste liquid with predetermined flow velocity；And
Add sodium nitrite solution and with top row acid waste liquid and carry out Passivation Treatment.
2. chemical cleaning method as claimed in claim 1, it is characterised in that: the citric acid adding different sour mass fractions in predetermined time interval includes:
The citric acid that acid mass fraction is 3.0%～2.5% is added when acid cleaning process starts；
After acid cleaning process starts first adds the citric acid that acid mass fraction is 2.5%～2.0% for three hours；
After acid cleaning process starts second adds the citric acid that acid mass fraction is 2.0%～1.5% for three hours；
After acid cleaning process starts the 3rd adds the citric acid that acid mass fraction is 1.5%～1.0% for three hours；
Last hour before acid cleaning process terminates adds the citric acid that acid mass fraction is 1.0%～0.5%.
3. chemical cleaning method as claimed in claim 1, it is characterised in that: also include after adding citric acid: addition ammonia the pH value regulating acid solution are 3～4.
4. chemical cleaning method as claimed in claim 1, it is characterised in that: in acid cleaning process, also include total iron concentration that timing detects in solution.
5. chemical cleaning method as claimed in claim 1, it is characterised in that: also include stopping wash cycles, static soak scheduled duration in acid cleaning process.
6. chemical cleaning method as claimed in claim 1, it is characterised in that: the pH value of described desalination solution is 8.5～10, and the addition flow velocity of described desalination solution is 8L/min～12L/min.
7. chemical cleaning method as claimed in claim 1, it is characterised in that: the pH value of described sodium nitrite solution is 9.5～11.
8. chemical cleaning method as claimed in claim 1, it is characterised in that: during sodium nitrite solution top row acid waste liquid, also include that timing detects the sour mass fraction at pipeline outlet and total iron concentration.
9. chemical cleaning method as claimed in claim 1, it is characterised in that: with sodium nitrite solution top row acid waste liquid time a length of 8～12 hours, during described passivation a length of 20～30 hours.
10. chemical cleaning method as claimed in claim 1, it is characterised in that: temperature when carrying out pickling with citric acid controls at 70～100 DEG C.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510028791.3A CN105862048A (en) | 2015-01-20 | 2015-01-20 | Chemical cleaning method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201510028791.3A CN105862048A (en) | 2015-01-20 | 2015-01-20 | Chemical cleaning method |
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|---|---|
| CN105862048A true CN105862048A (en) | 2016-08-17 |
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| CN201510028791.3A Pending CN105862048A (en) | 2015-01-20 | 2015-01-20 | Chemical cleaning method |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111826664A (en) * | 2020-06-02 | 2020-10-27 | 大晃机械（青岛）有限公司 | Metal cleaning liquid regeneration formula and regeneration method thereof |
-
2015
- 2015-01-20 CN CN201510028791.3A patent/CN105862048A/en active Pending
Non-Patent Citations (1)
| Title |
|---|
| 刘祥富: "PIG清洗和柠檬酸开路清洗的联合应用", 《清洗世界》 * |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111826664A (en) * | 2020-06-02 | 2020-10-27 | 大晃机械（青岛）有限公司 | Metal cleaning liquid regeneration formula and regeneration method thereof |
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Application publication date: 20160817 |