CN107326366B

CN107326366B - Application of corrosion inhibitor to improvement of aluminum-carbon steel galvanic corrosion of air-cooled circulating water system

Info

Publication number: CN107326366B
Application number: CN201710509755.8A
Authority: CN
Inventors: 许丽华; 赵长江; 付福军; 李敬业; 李韬弘; 秦立新; 银国文; 王小俊
Original assignee: Shenzhen Ener Chemistry Industrial Co ltd; Inner Mongolia Jingning Thermal Power Co ltd
Current assignee: Shenzhen Ener Chemistry Industrial Co ltd; Inner Mongolia Jingning Thermal Power Co ltd
Priority date: 2017-06-28
Filing date: 2017-06-28
Publication date: 2020-09-08
Anticipated expiration: 2037-06-28
Also published as: CN107326366A

Abstract

The invention discloses a pure aluminum-carbon steel galvanic corrosion inhibitor and a preparation method thereof, belonging to the technical field of galvanic corrosion inhibitors and comprising the following components: 20.0 to 100.0 weight portions of the component A; 0-60 parts of component B; the balance of desalted water; the component A comprises one or more of hydrazine hydrate and hydroxylamine; the component B contains one or more of L-ascorbic acid and sulfite, and the component A and the component B are compounded and then added into a circulating water system where the pure aluminum-carbon steel is positioned, so that the galvanic corrosion rate of the pure aluminum-carbon steel in the system can be effectively reduced.

Description

Application of corrosion inhibitor to improvement of aluminum-carbon steel galvanic corrosion of air-cooled circulating water system

Technical Field

The invention relates to the technical field of galvanic corrosion inhibitors, in particular to an aluminum-carbon steel galvanic corrosion inhibitor and a preparation method thereof.

Background

The indirect air cooling system of the supercritical generator set with the surface type condenser and the vertically arranged air cooling radiators is characterized in that steam turbine exhaust steam and exhaust steam of a steam feed pump enter the surface type condenser to be condensed by circulating water, the circulating water is pressurized by a circulating water pump after being heated and then enters a natural ventilation indirect air cooling tower to be cooled by air, and the cooled circulating water returns to the surface type condenser to form closed circulation.

Circulating water enters an air cooling tower after being boosted by a circulating water pump, and the diameter of 1 water inlet main pipe is DN 2400. And water cooled in the tower is returned to a condenser of a main plant for heat exchange through 1 DN2400 circulating water return pipe, and the heated water is returned to a circulating water pump to complete closed circulation.

The flow of the circulating water in the air cooling tower is as follows: air cooling tower circulating water main pipe → tower underground water inlet circular pipe → sector branch pipe → cooling triangle bottom water inlet main pipe → cooling triangle (pipe bundle) → cooling triangle bottom return water main pipe → sector branch pipe → tower underground water return circular pipe → cooling tower circulating water main pipe.

And a telescopic carbon steel expansion joint DN200 is arranged between the water inlet and outlet branch pipe at the bottom of the cooling triangle and the cooling triangle (pipe bundle).

The water inlet and outlet branch pipes and the expansion joint at the bottom of the cooling triangle are made of carbon steel materials and are electrically communicated with the whole circulating water pipeline system. The carbon steel expansion joint is detachably connected with a 1050A pure aluminum cooling triangle (pipe bundle) through a carbon steel half flange. Carbon steel and 1050A pure aluminum are dissimilar metals and, in the case of electrical connections, galvanic corrosion can occur. And the 1050A pure aluminum cooling triangle (tube bundle), the carbon steel huff flange and the expansion joint are connected with the same grounding grid, and the 1050A pure aluminum cooling triangle (tube bundle) and the huff flange form electric communication through the public grounding grid. Both of these electrical connections can lead to galvanic corrosion. Actual operating data prove that: it is the galvanic corrosion of the carbon steel-1050A pure aluminum that the circulating water system undergoes sudden increase of circulating water pH in a very short time after first water filling, and then large-area corrosion of 1050A pure aluminum radiators is initiated.

The cathodic protection is a common electrochemical corrosion prevention method for a metal structure of a condenser of a circulating water system of a power plant, and the metal potential is reduced by externally adding current or connecting sacrificial metal to obtain protection. Because 1050A pure aluminum heat dissipation triangle area of indirect air cooling circulating water system is huge and the structure is complicated, it is unrealistic to implement cathodic protection.

The insulation design between dissimilar metals is often the key point of the corrosion prevention design in the galvanic corrosion control technology and is emphasized, and in practical application, insulation measures are generally adopted between the corrosion-resistant metal with higher potential, such as titanium alloy, copper alloy and the like, and the steel component. For indirect air-cooling circulating water systems, the successful precedent of insulation design is not seen in complex corrosion structures in which carbon steel serves as a cathode in galvanic corrosion and also serves as an anode in a circulating water integral corrosion system.

The corrosion inhibitor is a simple, effective and feasible method for controlling the corrosion of the system. However, no special corrosion inhibitor for controlling galvanic corrosion exists at home and abroad at present, and other corrosion inhibitors are used for replacing the special corrosion inhibitor, so that the effect of controlling galvanic corrosion is not ideal. Particularly for supercritical indirect air-cooling circulating water systems, the corrosion inhibitor must also be capable of effectively controlling local corrosion and uniform corrosion of carbon steel, stainless steel and 1050A pure aluminum at the same time.

Galvanic corrosion refers to the phenomenon that when dissimilar metals are in contact with each other in the same medium, galvanic current flows due to unequal corrosion potentials, so that the dissolution rate of the metal with a lower potential is increased, and the dissolution rate of the metal with a higher potential is decreased.

The potential difference of dissimilar metals in corrosive medium is the necessary condition and driving force of galvanic corrosion, when different metal materials are contacted with each other in corrosive medium, a group of corrosion cells (corrosion couple) is formed, the metal with higher open-circuit potential is the cathode, the metal with lower open-circuit potential is the anode, the corrosion rate of the anode metal is increased, and the corrosion rate of the cathode metal is reduced.

When the potential difference of the dissimilar metals in the corrosive medium is more than 0.25V, the galvanic corrosion is more severe.

Disclosure of Invention

In order to overcome the defect that the effect of the existing corrosion inhibitor for controlling galvanic corrosion is not ideal, the invention provides the aluminum-carbon steel galvanic corrosion inhibitor and the preparation method thereof, which can control pure aluminum-carbon steel galvanic corrosion of a circulating water system of a supercritical indirect air cooling unit and can also control uniform corrosion rates of carbon steel, stainless steel and pure aluminum in circulating water.

The technical scheme adopted by the invention for solving the technical problems is as follows:

an aluminum-carbon steel galvanic corrosion inhibitor comprising:

20.0 to 100.0 weight portions of the component A;

0-60 parts of component B;

the balance of desalted water;

the component A comprises one or two of hydrazine hydrate and hydroxylamine;

the component B comprises one or more of L-ascorbic acid and sulfite.

Furthermore, the oxygen-removing regulator also comprises a proper amount of gas oxygen-removing regulator.

Further, the gas deoxygenation regulator is SO₂。

Further, the component A comprises the following components by taking the total weight as the reference:

20-60 parts of 80% hydrazine hydrate;

0-2.0 parts by weight of 50% hydroxylamine solution AR;

the balance of desalted water.

Further, the component B comprises the following components by taking the total weight as the reference:

further, the oxygen scavenging catalyst is cobalt sulfate or other soluble salt of one or more cobalt.

In order to solve the above technical problems, the present invention further provides a technical solution as follows:

a preparation method of any one of the aluminum-carbon steel galvanic corrosion inhibitors comprises the following steps:

selecting the components of the component A and weighing the components in parts by weight;

selecting the components of the component B and weighing the components in parts by weight;

determining the weight parts of the component A, the component B and the desalted water, and then mixing and uniformly stirring to form a mixed solution.

Further, the method also comprises the following steps:

after the mixed solution is added into the circulating water in which the aluminum-carbon steel couple is positioned, a proper amount of deoxidization catalyst is directly added into the circulating water.

Further, the method also comprises the following steps:

when the pH of the circulating water is greater than 8.8, injecting a gas deoxygenation regulator into the circulating water until the pH value of the circulating water is monitored to be reduced back to the range of 8.2-8.5.

Further, the control concentration of the corrosion inhibitor in the circulating water is as follows:

hydrazine: 10 mu g/L-40 mu g/L N₂H₄；

Ascorbic acid: 0-50 mu g/L C₆H₈O₆。

The invention provides an aluminum-carbon steel galvanic corrosion inhibitor and a preparation method thereof, wherein the circulating water of an aluminum-carbon steel galvanic couple is subjected to reductive treatment by a reducing agent mixture compounded by a component A and a component B, the electrochemical state of a carbon steel, stainless steel and pure aluminum corrosion system is adjusted, and the purpose of reducing the corrosion rate of anode metal pure aluminum with lower potential is achieved by reducing the concentration of oxygen of a depolarizer participating in the cathode corrosion process and increasing the cathode polarization capacity of a corrosion electrode.

Drawings

FIG. 1 is a schematic diagram showing the simulation of the working principle of the corrosion inhibitor of the present invention;

FIG. 2 is a graph of corrosion potential of 1050A pure aluminum in pure water versus hydrazine concentration;

FIG. 3 is a graph showing the relationship between the corrosion potential of 1050A pure aluminum and the hydrazine concentration in simulated circulating water;

FIG. 4 is a graph of corrosion potential versus hydrazine concentration for carbon steel under pure water conditions;

FIG. 5 shows pH vs. SO₂、HSO₃ ^-And SO₃ ^2-Influence graphs of three morphological distributions;

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The invention provides an aluminum-carbon steel galvanic corrosion inhibitor, which comprises: 20.0 to 100.0 weight portions of the component A, 0 to 60 weight portions of the component B and the balance of desalted water; the component A comprises one or more of hydrazine hydrate and hydroxylamine; the component B comprises one or more of L-ascorbic acid and sulfite. Wherein the component A comprises the following components in parts by weight: 20-60 parts by weight of 80% hydrazine hydrate; 0-2.0 parts by weight of 50% hydroxylamine solution (AR) and the balance of demineralized water. The component B comprises the following components in parts by weight: 0-25 parts by weight of L-ascorbic acid (GR), 0-5.0 parts by weight of ammonium bisulfite; 0-0.5 parts by weight of an oxygen-scavenging catalyst; and the balance of demineralized water. If desired, a suitable amount of a gas oxygen-scavenging modifier, e.g. SO₂. The gas deoxidization regulator is only used for the working condition that the circulating water has sudden pH rise accident, and SO is added₂The control standard of (2) is to control the pH value of the circulating water to be in the range of 8.2-8.5.

Preferably, the component a is selected from 80% of hydrazine hydrate as a main agent and 50% of hydroxylamine as an auxiliary agent, and the content of the hydrazine hydrate is preferably 20-60 wt%, and more preferably 31.25 wt%, based on the total weight of the component a. The content of hydroxylamine is preferably 0.05 to 2.0% by weight, more preferably 0.10% by weight.

For example, 1000g of component A is prepared, (hydrazine content: 160 g/kgN)₂H₄) The components are as follows:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

In addition, the method is characterized in that: calculating the content of hydrazine:

the hydrazine reacts with water to form weak alkaline, and the reaction equation is as follows:

N₂H₄+H₂O→N₂H₅ ⁺+OH^-formation of a monovalent hydrazine ion N₂H₅ ⁺， (10)

First order ionization constant of 1.0 × 10^-6(298K)；

N₂H₄+2H₂O→N₂H₆ ²⁺+20H^-' formation of N + divalent hydrazine ion₂H₆ ²⁺， (11)

Second order ionization constant of 9.0 × 10^-16(298K)。

Preferably, the component B comprises L-ascorbic acid as a main agent, ammonium bisulfite as an auxiliary agent, an oxygen removal catalyst and an aqueous solution. The content of the L-ascorbic acid is preferably 1 to 10% by weight, more preferably 8.0% by weight, based on the total weight of the component B. The content of ammonium bisulfite is preferably 0 to 5.0 wt.%, more preferably 1.0 wt.%. The oxygen scavenging catalyst is a cobalt salt, preferably cobalt sulfate, preferably in an amount of 0 to 0.5 wt.%, more preferably 0.1 wt.%. The content of the desalted water is preferably 60 to 98% by weight, more preferably 91% by weight.

For example, the preparation of component B1000 g: (L-ascorbic acid content: 80g/kg C)₆H₈O₆) The components are as follows:

l-ascorbic acid GR (99.7%) 80.0g (8%);

ammonium bisulfite 10.0g (1%);

910.0g (91%) of demineralized water.

The molecular structure of L-ascorbic acid is shown below:

it has been found that the contact of a metal with a low electrode potential with a metal with a high electrode potential only accelerates the corrosion itself, rather than causing the root cause of corrosion, and galvanic corrosion cannot be defined as "corrosion of a metal due to contact with a metal with a high electrode potential". The root cause for the galvanic corrosion (contact corrosion) process to occur is still due to the presence of the cathodic depolarizer in the solution. The potential difference only determines whether galvanic corrosion can occur and the direction of the corrosion current, and the degree of galvanic corrosion depends on the polarization capability of each metal in the corrosion medium.

Taking the problem of 1050A pure aluminum-carbon steel galvanic corrosion as an example, oxygen in the circulating water is the only cathode depolarizer for 1050A pure aluminum-carbon steel galvanic corrosion, and the technical route of 1050A pure aluminum-carbon steel galvanic corrosion inhibitor reagent is to enhance cathode polarization or increase the activation energy of oxygen reduction reaction. Preventing oxygen molecules from participating in the reduction reaction for accepting electrons if the oxygen in the circulating water is completely removed, the metal will not corrode.

The corrosion inhibitor is prepared according to the formula, the corrosion inhibitor is added into a 1050A pure aluminum/pure water corrosion system, and the control concentration of the corrosion inhibitor in circulating water is as follows:

component a (hydrazine): 10 mu g/L-40 mu g/LN₂H₄Preferably 16. mu.g/LN₂H₄

Component B (L-ascorbic acid): 0-80 mu g/L C₆H₈O₆，

Preferably: pH > 8.5, 40. mu.g/L C₆H₈O₆；

pH≤8.5，0μg/L C₆H₈O₆。

Other auxiliary components are added into the circulating water according to the proportion of the formula of the component A and the formula of the component B, and no additional metering control is needed.

After the corrosion inhibitor is added into a 1050A pure aluminum/pure water corrosion system, an oxidation reaction capable of losing electrons is spontaneously provided: (1) a(2) And (3), (15) and (16), i.e. coupling new anodic currents (i) in the corrosion system_aN2H4、i_aC6H806、i_aNH2OHAnd

) (FIG. 1), these new anodic currents introduced into the corrosion system and the original anodic corrosion current in the 1050A pure aluminum/pure water corrosion system, i.e., the corrosion current of aluminum (i)⁰ _aAl) Coupling to form a new corrosion electrochemical system. The electron gain of the oxygen molecule of the cathode depolarizer is the only cathode current (i) coupled in the 1050A pure aluminum/pure water corrosion system_c02)。

Oxidation reaction of hydrazine aqueous solution:

N₂H₄+40H^--4e^-＝N₂+4H₂O -1.15V SHE (1)

N₂H₅ ⁺-50H^--4e^-＝N₂+5H₂O -0.23V SHE (2)

oxidation of ascorbic acid:

oxidation reaction of sulfite: SO (SO)₄ ^2-+H₂O+2e^-═SO₃ ^2-+2OH^-(15)

Oxidation reaction of hydroxylamine: n is a radical of₂+4H₂O+2e^-＝2NH₂OH+2OH^-(16)

According to the theory of corrosion electrochemistry about polarization and mixed potential, under the stable state of mixed potential, the total faradaic admittance of the electrode surface reaction is the sum of the faradaic admittances of the respective electrode reactions, namely the sum of all coupled anodic reaction currents on the surface of the corrosion electrode is equal to the sum of all coupled cathodic reaction currents. Therefore, if a new anodic reaction current is introduced in the anodic reaction in equilibrium with the limiting diffusion current of the cathodic oxygen uptake reaction, the original unique anodic reaction current-the anodic reaction (corrosion) current of aluminum (i.e., corrosion rate) in the system can be reduced or suppressed.

According to the mixed potential theory:

mixed potential equation before treatment:

mixed potential equation after treatment:

obviously: hydrazine, ascorbic acid, hydroxylamine and Sulfite (SO) were added to 1050A pure aluminum/pure water etch system₃ ^2-) After the reducing agent treatment, the corrosion rate of 1050A pure aluminum is reduced.

i_cO2Limiting diffusion current i ═ oxygen_d：

In the formula: n oxidation reduction reaction gain and loss electron number, and the cathode reaction under the condition of neutral and alkaline pure water is as follows: o is₂+2H₂O+4e^-＝4OH^-N is 4; f, a Faraday constant of 96500 coulombs/mol; d: the diffusion coefficient of oxygen in water; c, the concentration of dissolved oxygen; : the thickness of the diffusion layer.

FIG. 1 depicts the working principle of the corrosion inhibitor:

corrosion electrode reaction before treatment (addition of corrosion inhibitor) (left side of fig. 1):

and (3) anode reaction: al +4OH^—-3e^-＝H₂AlO₃+H₂O (8)

And (3) cathode reaction: o is₂+2H ₂0+4e^-＝4OH^-(9)

Corrosion electrode reaction after treatment (addition of corrosion inhibitor) (right side of fig. 1):

and (3) anode reaction:

Al+4OH^—-3e^-＝H₂AlO₃+H₂O (8)

N₂H₄+4OH^—-4e^-＝N₂+4H₂O (1)

N₂H₅ ⁺-5OH^--4e^-＝N₂+5H₂O (2)

SO₄ ^2-+H₂O+2e^-═SO₃ ^2-+2OH^-(15)

N₂+4H₂O+2e^-＝2NH₂OH+2OH^-(16)

and (3) cathode reaction: o is₂+2H ₂0+4e^-＝4OH^-(9)

FIG. 2 is a graph of corrosion potential of 1050A pure aluminum in pure water versus hydrazine concentration; the results of the study in the figure demonstrate that: after the hydrazine is added, the corrosion potential of pure aluminum in the system is shifted significantly to the negative.

FIG. 3 is a graph of corrosion potential of 1050A pure aluminum in a simulated circulating water medium containing aluminum and chloride ions as a function of hydrazine concentration, and it can be shown from the graph that: after hydrazine is added, the corrosion potential of 1050A pure aluminum obviously moves towards negative, and the phenomenon of negative corrosion potential movement indicates that: hydrazine is a cathode type corrosion inhibitor which mainly inhibits the cathode oxygen absorption reaction of an aluminum electrode to realize the corrosion inhibition effect on 1050A pure aluminum.

FIG. 4 is a plot of corrosion potential versus hydrazine concentration for carbon steel under pure water conditions; as can be seen from the data in fig. 4, the corrosion potential of the carbon steel system shifts significantly to the positive after hydrazine addition, and the results of the study demonstrate that: hydrazine is a typical anode type corrosion inhibitor which realizes the corrosion inhibition effect on carbon steel by inhibiting the anode reaction of a carbon steel electrode.

Further through electrochemical impedance studies, it was also found that: the corrosion of 1050A pure aluminum is typically controlled by an oxygen diffusion process, and the corrosion rate of 1050A pure aluminum can be reduced by reducing the concentration of oxygen in the circulating water as a cathode depolarizer according to equation (7). Therefore, a normal-temperature deoxidant is added into the formula of the corrosion inhibitor for compounding, so that the corrosion inhibition efficiency of the corrosion inhibitor can be improved.

The data actually measured demonstrate that: the corrosion inhibitor provided by the invention has a good function of controlling the galvanic corrosion of 1050A pure aluminum-carbon steel, and can reduce the uniform corrosion rate of carbon steel, stainless steel and 1050A pure aluminum.

Therefore, after the corrosion inhibitor of the invention is added into a 1050A pure aluminum/pure water corrosion system, the oxidation reactions (1), (2), (3), (15) and (16) of the corrosion inhibitors under alkaline conditions change the mixed potential and corrosion current of the corrosion system, reduce the corrosion speed and achieve the technical purpose of the invention.

In order to enhance the galvanic corrosion control effect of the corrosion inhibitor, the corrosion inhibitor adopts a gas deoxygenation regulator SO₂. Gas deoxidization regulator SO₂Should be placed at the inlet tube of the hydrazine dosing pump.

In demineralized water: SO (SO)₂、HSO₃ ^-、SO₃ ^2-The three forms maintain the following chemical equilibrium relationship

Gas deoxidization regulator SO₂Can enhance the reducibility of a circulating water corrosion system, and simultaneously generate a reaction product H⁺Can reduce the pH value of the circulating water and protect 1050A pure aluminum from forming a passivation film in the water. The "gas oxygen-scavenging regulator" is characterized in that: only when the circulating water is used for the accident condition of sudden pH rise, SO is added₂The control standard of (2) is to control the pH value to be in the range of 8.2-8.5.

During chemical oxygen removal, no matter how much SO is added₂Or HSO₃ ^-All need to be converted into SO₃ ^2-Can be in the form of₂The molecule completes the reaction process of oxygen removal:

2SO₃ ^2-+O₂＝2SO4^2-(14)

an electrochemical reaction equation in the oxygen removal process;

and (3) anode reaction: SO (SO)₄ ^2-+H₂O+2e═SO₃ ^2-+2OH^-(15)

And (3) cathode reaction: o is₂+2H ₂0+4e^-＝4OH^-(9)

Known as SO₃ ^2-And is also a strong reducing agent, and participates in the electrode reaction together with hydrazine and ascorbic acid according to equation (15), so that new anode current is introduced into the corrosion system, and the corrosion rate of 1050A pure aluminum is further reduced.

FIG. 5 is the pH value vs. SO₂、HSO₃ ^-And SO₃ ^2-Influence diagrams of three morphological distributions. It can be seen that the pH of the circulating water is an important factor affecting the rate of oxidation of the sulfite. As can be seen from FIG. 5, SO₂、HSO₃ ^-And SO₃ ^2-The three reactants are in equilibrium with the pH value of the circulating water, SO₃ ^2-The conditions under which the concentration share is greatest are those under which the oxygen-scavenging reaction rate is highest. pH8.5 is the pH at which the sulfite has the best effect in removing oxygen.

Based on the above corrosion inhibitor formulation and preparation method, the following specific examples are presented.

Example one

This example prepares an Al-carbon steel galvanic corrosion inhibitor for use in a 350MW supercritical indirect air cooling circulating water system (water volume 7000 m)³)。

The adopted formula structure is as follows:

100.0% of component A;

0% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

the control of the dosing concentration is as follows: the hydrazine concentration is: 16 μ g/L N₂H₄(ii) a I.e. 16mg/m³N₂H₄；

L-ascorbic acid concentration: 0. mu.g/L C₆H₈O₆。

The calculated hydrazine dosage is 16 × 7000-112 g N₂H₄，

The formula of the component A comprises the following hydrazine content: 160g/kg N₂H₄；

The amount of the component A needs to be added is as follows:

the amount of the component B to be added is as follows: 0.

starting the unit commercial operation from 12/19/2015 to 27/4/2017, and stopping the unit, wherein the chemical supervision and inspection result is as follows: neither 1050A pure aluminum, 304 stainless steel corrosion indicator test piece nor 1050A pure aluminum-carbon steel couple has corrosion weight loss, and the average corrosion rate of the carbon steel corrosion indicator test piece is 0.015mm/a, which is superior to the standard of GB50050-2007 industrial circulating cooling water treatment design specification: 0.075 mm/a. When the corrosion test piece is observed under a metallographic microscope with the magnification of 1000 times, pitting corrosion and other corrosion conditions can not be observed.

Example two:

the aluminum-carbon steel galvanic corrosion inhibitor prepared in the implementation is used for the water volume of a 350MW supercritical indirect air cooling circulating water system of 7000m³(ton), the following formula structure is adopted:

55.6 percent of component A;

44.4% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

the preferred formula of component B is:

l-ascorbic acid GR (99.7%) 80.0g (8%);

ammonium bisulfite 10.0g (1%);

910.0g (91%) of demineralized water.

Operating system dosing (pH > 8.5)

Adding medicine to control the concentration: the hydrazine concentration is: 40 μ g/L N₂H₄(ii) a L-ascorbic acid concentration: 16 μ g/L C₆H₈O₆。

Calculating the hydrazine dosage of 40 × 7000 to 280g N₂H₄，

The formula of the component A has hydrazine content: 160g/kg N₂H₄；

The amount of the component A required to be added is as follows:

the dosage of the L-ascorbic acid is as follows: 16 × 7000 ═ 112g

The formula of the component B has the following ascorbic acid content: 80g/kg C₆H₈O₆

The amount of the component B required to be added is as follows:

250mL of the water sample of the embodiment is taken, a CS310 type electrochemical workstation is adopted to carry out potentiodynamic scanning polarization curve measurement, the scanning potential range is from-0.2V (relative open circuit) to +0.2V (relative open circuit), the scanning speed is 1mV/s, and the sampling speed is 2 Hz.

The method for accurately calculating the corrosion potential and the corrosion rate according to the Tafel curve is the most accurate method for measuring the corrosion rate internationally and generally at present. And calculating the Tafel slope of the cathode and the anode, the corrosion rate, the polarization resistance and other corrosion parameters by adopting a nonlinear three-parameter method.

And (3) measuring results: corrosion rate of 1050A pure aluminum in the above medium: 0.00011 mm/a; less than 0.05 mm/a.

Example three:

100.0% of component A;

0% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

The formula of the component A has hydrazine content: 160g/kg N₂H₄；

The operation system is set as follows: materials: 1050A pure aluminum; corrosion medium: demineralized water (ph7.2), hydrazine concentration: 40 ug/LN₂H₄(ii) a Ascorbic acid concentration: 0. mu.g/L C₆H₈O₆。

The method for accurately calculating the corrosion potential and the corrosion rate according to the Tafel curve is the most accurate method for measuring the corrosion rate internationally and generally at present. The curve adopts a nonlinear three-parameter method to calculate the Tafel slope of the cathode and the anode, the corrosion rate, the polarization resistance and other corrosion parameters.

The measurement result shows that the corrosion rate of 1050A pure aluminum in the medium is 6.4 × 10^-5mm/a; less than 0.05 mm/a.

The galvanic corrosion current is measured by adopting electrochemical noise, and the measurement result is as follows:

1050A pure aluminum-carbon steel galvanic corrosion current density in the above medium: 0.1. mu.A/cm²(ii) a Is superior to the A-grade standard of 0.3 muA/cm specified by the aviation standard HB5374²。

Example four:

the corrosion inhibitor has the following formula structure:

100.0% of component A;

0% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

The formula of the component A has hydrazine content: 160g/kg N₂H₄；

The hydrazine concentration is: 40 μ g/L N₂H₄(ii) a Ascorbic acid concentration: 0. mu.g/L C₆H₈O₆。

The operation system is set as follows: materials: 1050A pure aluminum; corrosion medium: simulated circulating water (artificially added 156 mug/LCl)^-) pH8.7, pure water + 40. mu.g/L Al³⁺+156μg/L Cl^-；

1050A pure aluminum has the corrosion rate of 10 × 10 in the medium^-5mm/a; less than 0.05 mm/a.

Carbon steel corrosion rate: 0.018mm/a, which is superior to the standard of GB50050-2007 industrial circulating cooling water treatment design specification: 0.075 mm/a.

1050A pure aluminum-carbon steel galvanic corrosion current density: 0.53. mu.A/cm²(ii) a Meets the B-level standard specified by the aviation standard HB 5374: 0.3. mu.A/cm²＜i_g＜1.0μA/cm²。

Example five:

100.0% of component A;

0% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

The formula of the component A has hydrazine content: 160g/kg N₂H₄；

The operation system is set as follows: materials: 1050A pure aluminum; corrosion medium: pure water, pH 7.1, hydrazine: 16 μ g/L (N)₂H₄) Ascorbic acid: 0

The measurement results are:

corrosion rate: 0.000023 mm/a. Less than 0.05 mm/a.

Example six:

100.0% of component A;

0% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

The formula of the component A has hydrazine content: 160g/kg N₂H₄

The system environment is set as follows: materials: 1050A pure aluminum; corrosion medium: pure water, pH 7.1, hydrazine: 40 μ g/L (N)₂H₄) Ascorbic acid: 0.

The measurement results are:

corrosion rate: 0.00014 mm/a. Less than 0.05 mm/a.

Example seven:

the formula structure of the corrosion inhibitor is as follows:

55.6 percent of component A;

44.4% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

the preferred formula of component B is:

l-ascorbic acid GR (99.7%) 80.0g (8%);

ammonium bisulfite 10.0g (1%);

910.0g (91%) of demineralized water.

7000m³Adding the dosage of circulating water:

adding medicine to control the concentration: the hydrazine concentration is: 40 μ g/L N₂H₄(ii) a L-ascorbic acid concentration：16μg/L C₆H₈O₆。

Calculating the hydrazine dosage of 40 × 7000 to 280g N₂H₄，

The formula of the component A has hydrazine content: 160g/kg N₂H₄；

The amount of the component A required to be added is as follows:

the dosage of the L-ascorbic acid is as follows: 16 × 7000 ═ 112g

The amount of the component B required to be added is as follows:

the system environment is set as follows: materials: 1050A pure aluminum

Corrosion medium: pure water, pH8.7 (aluminum: 40. mu.g/LAl)³⁺And chloride ion: 156. mu.g/LCl^-，

Hydrazine: 40 μ g/L N₂H₄Ascorbic acid: 16 μ g/L C₆H₈O₆)

The measurement results are:

corrosion rate: 0.00010 mm/a. Less than 0.05 mm/a.

Example eight:

in this embodiment, an aluminum-carbon steel galvanic corrosion inhibitor is prepared for use in the preparation of the corrosion inhibitorWater volume of 50MW supercritical indirect air cooling circulating water system is 7000m³(ton), the following formula structure is adopted: 100.0% of component A;

0% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

The formula of the component A has hydrazine content: 160g/kg N₂H₄；

The system environment is set as follows:

materials: 1050A pure aluminum; corrosion medium: pure water, pH8.7 (aluminum: 40. mu.g/L Al)³⁺And chloride ion: 156 μ g/L Cl^-,

Hydrazine: 16 μ g/L N₂H₄Ascorbic acid: 0

The measurement results are:

corrosion rate: 0.00029 mm/a. Less than 0.05 mm/a.

Example nine:

55.6 percent of component A;

44.4% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

the preferred formula of component B is:

l-ascorbic acid GR (99.7%) 80.0g (8%);

ammonium bisulfite 10.0g (1%);

910.0g (91%) of demineralized water.

7000m³Adding the dosage of circulating water:

Calculating the hydrazine dosage of 40 × 7000 to 280g N₂H₄，

The formula of the component A has hydrazine content: 160g/kg N₂H₄；

The amount of the component A required to be added is as follows:

the dosage of the L-ascorbic acid is as follows: 16 × 7000 ═ 112g

The amount of the component B required to be added is as follows:

system environment deviceThe method comprises the following steps: materials: 304 stainless steel; corrosion medium: pure water, pH8.7 (aluminum: 40. mu.g/L Al)³⁺And chloride ion: 156 μ g/L Cl^-Hydrazine: 16 μ g/L N₂H₄Ascorbic acid: 16 μ g/L C₆H₈O₆)

The measurement results are:

corrosion rate: 0.00054mm/a, which is superior to the standard requirement that the corrosion rate of the stainless steel is less than 0.005mm/a specified in GB50050-2007 design Specification for Industrial circulating Cooling Water treatment.

Example ten:

55.6 percent of component A;

44.4% of component B.

The preferred formula of component A is:

80% hydrazine hydrate 312.5g

(31.25％)；

50% hydroxylamine solution AR1.0g (0.1%);

686.5g of demineralized water (68.65%).

the preferred formula of component B is:

l-ascorbic acid GR (99.7%) 80.0g (8%);

ammonium bisulfite 10.0g (1%);

910.0g (91%) of demineralized water.

7000m³Adding the dosage of circulating water:

Calculating the hydrazine dosage of 40 × 7000 to 280g N₂H₄，

The formula of the component A has hydrazine content: 160g/kg N₂H₄；

The amount of the component A required to be added is as follows:

the dosage of the L-ascorbic acid is as follows: 16 × 7000 ═ 112g

The amount of the component B required to be added is as follows:

the system environment is set as follows:

materials: carbon steel; corrosion medium: pure water, pH8.7 (aluminum: 40. mu.g/L Al)³⁺And chloride ion: 156 μ g/L Cl^-Hydrazine: 40 μ g/L N₂H₄Ascorbic acid: 16 μ g/L C₆H₈O₆)

The measurement results are:

corrosion rate: 0.035mm/a, which is superior to the standard requirement that the corrosion rate of the carbon steel specified in GB50050-2007 design Specification for industrial circulating cooling water treatment is less than 0.075 mm/a.

The test result shows that: the corrosion rates of 1050A pure aluminum-carbon steel couple corrosion and 1050A pure aluminum and carbon steel in the tested corrosion medium reach the control range specified by the relevant standard.

The preferred embodiments of the present invention have been described above with reference to the accompanying drawings, and are not to be construed as limiting the scope of the invention. Those skilled in the art can implement the invention in various modifications, such as features from one embodiment can be used in another embodiment to yield yet a further embodiment, without departing from the scope and spirit of the invention. Any modification, equivalent replacement and improvement made within the technical idea of using the present invention should be within the scope of the right of the present invention.

Claims

1. The application of the corrosion inhibitor in improving the aluminum-carbon steel galvanic corrosion of the air-cooling circulating water system is characterized in that:

selecting 20.0-100.0 parts by weight of component A;

the component A comprises 20-60 wt% of 80% hydrazine hydrate, 0.05-2.0 wt% of 50% hydroxylamine solution AR, and the balance of demineralized water;

selecting 0-60 parts by weight of component B;

the component B comprises:

mixing and stirring uniformly to form the corrosion inhibitor, and adding the corrosion inhibitor into a circulating water system.

2. The use of the corrosion inhibitor according to claim 1 for improving aluminum-carbon steel galvanic corrosion in air-cooled circulating water systems, characterized in that an appropriate amount of a gas oxygen-removal modifier is also added to the circulating water system.

3. The use of the corrosion inhibitor according to claim 2 for improving aluminum-carbon steel galvanic corrosion of air-cooled circulating water systems, characterized in that: the gas deoxidization regulator is SO₂。

4. The use of the corrosion inhibitor according to claim 1 for improving aluminum-carbon steel galvanic corrosion of air-cooled circulating water systems, characterized in that:

the oxygen scavenging catalyst is cobalt sulfate or other soluble salt of one or more cobalt.

5. The use of the corrosion inhibitor according to claim 1 for improving galvanic corrosion of aluminum-carbon steel in air-cooled circulating water systems, further comprising: