Polyamine boiler water treatment agent and preparation method thereof

Abstract

The invention relates to the technical field of water treatment, in particular to a polyamine boiler water treatment agent and a preparation method thereof. The preparation method comprises the following steps: firstly, dissolving N-oleyl-1, 3-propylene diamine in cyclohexylamine, and then adding water to obtain the polyamine boiler water treatment agent. The agent provided by the invention takes the film-forming amine (N-oleyl-1, 3-propylene diamine) and the neutralizing amine (cyclohexylamine) as main components, is simple to prepare and harmless to the environment, can effectively relieve metal corrosion of a boiler steam-water system, and is an efficient and environment-friendly boiler water treatment agent suitable for middle and high pressure boilers.

Description

Technical Field

[0001] The invention relates to the technical field of water treatment, and in particular to a polyamine boiler water treatment agent and a preparation method thereof. Background Art

[0002] When metals in boiler steam-water systems come into contact with water and steam at higher temperatures, chemical and electrochemical reactions will occur, destroying the metals and causing metal corrosion. This is a common phenomenon in boiler steam-water systems, which can easily cause accidents such as failure of the heating surface, and have a significant impact on the operation of the entire boiler system. Water is the basic condition for ensuring the normal use of the boiler, and its quality directly affects the operating efficiency and safety of the boiler. After pretreatment of the boiler feed water, suspended matter, colloids, and most salts in the water are removed, but since the boiler does not have a deoxygenation system or the deoxygenation is not thorough, oxygen is still contained in the water. In addition, the carbonates contained in the water decompose to produce gases such as carbon dioxide, which can easily cause corrosion of boiler equipment. Dissolved oxygen corrosion and carbon dioxide corrosion are the main causes of corrosion in boiler steam-water systems.

[0003] In the boiler water treatment system, it is difficult to remove all the oxygen in the water using a thermal deaerator alone, and the residual oxygen gradually concentrates and causes corrosion. Therefore, chemical deoxygenation must be used at the same time as thermal deoxygenation, that is, adding deoxygenators to the water to reduce dissolved oxygen corrosion. Carbon dioxide causes corrosion of boiler steam and water system equipment mainly because carbon dioxide causes the pH of the water to drop, causing acid corrosion. Usually, neutralizers, namely neutralizing amines, are added to the water to control the pH of the feed water to reduce carbon dioxide corrosion. Adding traditional water treatment agents such as ammonia, hydrazine, and trisodium phosphate to boiler water can effectively reduce the corrosion of boiler steam and water system equipment, but these substances have certain disadvantages due to their own nature limitations, and there are also many problems when added to boiler water as water treatment agents.

[0004] Ammonia water has a pungent odor, is greatly affected by temperature, and has poor stability. It has a large distribution coefficient between the steam and liquid phases, which makes the pH of the condensed water low when the steam just condenses, resulting in initial condensation corrosion of equipment such as steam turbines. When copper alloy materials are present in the equipment, ammonia and copper ions will form a stable copper-ammonia complex, which accelerates the corrosion of copper alloy materials. Hydrazine is an extremely toxic and carcinogenic substance. Its reaction with dissolved oxygen in water is greatly affected by water temperature, pH value, etc. It cannot react completely with oxygen, resulting in residues in the steam. Sodium phosphate cannot form an effective passivation film on the inner wall of the boiler under high temperature and high pressure, and it is easy to form phosphate iron scale with iron ions in the boiler water, causing scaling of the water-cooled wall. In addition, phosphate has limited ability to adjust the pH of boiler water. When the boiler increases the load, phosphate is prone to "hiding", resulting in excessive or insufficient addition of sodium phosphate. As the country's requirements for phosphorus emissions become more and more stringent, the use of phosphate agents is further restricted. Therefore, it is necessary to develop new, efficient and environmentally friendly boiler water treatment agents. Summary of the invention

[0005] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a polyamine boiler water treatment agent and a preparation method thereof.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0007] On the one hand, a method for preparing a polyamine boiler water treatment agent is provided, which comprises the following steps:

[0008] Firstly, N-oleyl-1,3-propylene diamine is dissolved in cyclohexylamine, and then water is added to obtain a polyamine boiler water treatment agent.

[0009] Furthermore, the treatment temperature is 30-40°C.

[0010] Furthermore, the concentration of N-oleyl-1,3-propylene diamine is 10-15 g / L.

[0011] Furthermore, the mass ratio of N-oleyl-1,3-propylenediamine / cyclohexylamine is 1:(1-2.5).

[0012] On the other hand, a polyamine boiler water treatment agent prepared by the above method is provided.

[0013] The beneficial effects of the present invention are:

[0014] The agent of the present invention has film-forming amine (N-oleyl-1,3-propylene diamine) and neutralizing amine (cyclohexylamine) as main components, is simple to prepare, is harmless to the environment, can effectively reduce metal corrosion in boiler steam-water systems, and is a highly efficient and environmentally friendly boiler water treatment agent suitable for medium and high pressure boilers. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The polyamine boiler water treatment agents prepared in the examples have N-oleyl-1,3-propylene diamine concentrations of 10 g / L and 15 g / L respectively (experimental temperature 30°C, N-oleyl-1,3-propylene diamine / cyclohexylamine mass ratio of 1:2);

[0016] Figure 2 The polyamine boiler water treatment agent prepared in the example has a mass ratio of N-oleyl-1,3-propylene diamine / cyclohexylamine of 1:1, 1:2 and 1:2.5 respectively (experimental temperature 30°C, N-oleyl-1,3-propylene diamine concentration 10g / L);

[0017] Figure 3 The polyamine boiler water treatment agent prepared in the example at the experimental temperatures of 30°C and 40°C (N-oleyl-1,3-propylene diamine concentration of 10 g / L, N-oleyl-1,3-propylene diamine / cyclohexylamine mass ratio of 1:2);

[0018] Figure 4 This is the macroscopic morphology of the boiler carbon steel after corrosion cleaning in the pure water medium (left) and the medium containing polyamine reagent (right) in the test example (the dissolved oxygen concentration of pure water is 8300μg / L, and the test temperature is 150℃). DETAILED DESCRIPTION

[0019] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0020] The present invention uses film-forming amine (N-oleyl-1,3-propylene diamine) and neutralizing amine (cyclohexylamine) as main components to prepare a polyamine boiler water treatment agent. The preparation of the agent is related to factors such as the order of adding reagents, the concentration of the film-forming amine, the concentration of the neutralizing amine, and the experimental temperature. When water is added to N-oleyl-1,3-propylene diamine, floccules are formed, while when cyclohexylamine is added to N-oleyl-1,3-propylene diamine, it can be completely dissolved in the cyclohexylamine, and when water is added, a uniform emulsion is formed.

[0021] Example 1

[0022] First, N-oleyl-1,3-propylene diamine is dissolved in cyclohexylamine, and then water is added to obtain a polyamine boiler water treatment agent. In this embodiment, the experimental temperature is 30°C, the mass ratio of N-oleyl-1,3-propylene diamine / cyclohexylamine is 1:2, and the concentration of N-oleyl-1,3-propylene diamine is 10g / L.

[0023] Example 2

[0024] First, N-oleyl-1,3-propylene diamine is dissolved in cyclohexylamine, and then water is added to obtain a polyamine boiler water treatment agent. In this embodiment, the experimental temperature is 30°C, the mass ratio of N-oleyl-1,3-propylene diamine / cyclohexylamine is 1:2, and the concentration of N-oleyl-1,3-propylene diamine is 15g / L.

[0025] Example 3

[0026] First, N-oleyl-1,3-propylene diamine is dissolved in cyclohexylamine, and then water is added to obtain a polyamine boiler water treatment agent. In this embodiment, the experimental temperature is 30°C, the mass ratio of N-oleyl-1,3-propylene diamine / cyclohexylamine is 1:1, and the concentration of N-oleyl-1,3-propylene diamine is 10g / L.

[0027] Example 4

[0028] First, N-oleyl-1,3-propylene diamine is dissolved in cyclohexylamine, and then water is added to obtain a polyamine boiler water treatment agent. In this embodiment, the experimental temperature is 30°C, the mass ratio of N-oleyl-1,3-propylene diamine / cyclohexylamine is 1:2.5, and the concentration of N-oleyl-1,3-propylene diamine is 10g / L.

[0029] Example 5

[0030] First, N-oleyl-1,3-propylene diamine is dissolved in cyclohexylamine, and then water is added to obtain a polyamine boiler water treatment agent. In this embodiment, the experimental temperature is 40°C, the mass ratio of N-oleyl-1,3-propylene diamine / cyclohexylamine is 1:2, and the concentration of N-oleyl-1,3-propylene diamine is 10g / L.

[0031] The polyamine boiler water treatment agents prepared in Examples 1 to 5 are all uniform emulsions. After standing for 15 days, the emulsions did not stratify, indicating that the prepared polyamine boiler water treatment agents are stable in nature.

[0032] Test example

[0033] The polyamine boiler water treatment agent prepared in the embodiment of the present invention has film-forming amine (N-oleyl-1,3-propylene diamine) and neutralizing amine (cyclohexylamine) as main components, and is an environmentally friendly boiler water treatment agent. In the boiler steam-water system metal corrosion simulation experiment, when the concentration of the polyamine boiler water treatment agent (prepared in Example 1) in pure water is 4 mg / L, at 150°C and the pure water dissolved oxygen concentration is 10 μg / L, the corrosion inhibition rate of boiler carbon steel is 53.84%, at 350°C and the pure water dissolved oxygen concentration is 10 μg / L, the corrosion inhibition rate of boiler carbon steel is 29.96%, and at 150°C and the pure water dissolved oxygen concentration is 8300 μg / L, the corrosion inhibition rate of boiler carbon steel is 86.08%. This shows that the agent has a good inhibitory effect on the metal corrosion of the boiler steam-water system.

[0034] The main component of the agent of the present invention, film-forming amine, i.e., N-oleyl-1,3-propylene diamine, has poor solubility in water. Cyclohexylamine is used as a co-solvent to dissolve N-oleyl-1,3-propylene diamine, thereby preparing a polyamine boiler water treatment agent with N-oleyl-1,3-propylene diamine as a main component. Cyclohexylamine not only has the function of a co-solvent, but also can adjust the pH value as a neutralizing amine.

[0035] In summary, the present invention provides a polyamine boiler water treatment agent and a preparation method thereof. The agent has a film-forming amine (N-oleyl-1,3-propylene diamine) and a neutralizing amine (cyclohexylamine) as main components, forms a hydrophobic protective film on the metal surface, isolates corrosive substances such as oxygen and carbon dioxide from contacting the metal to reduce corrosion of boiler steam-water system equipment, and is an environmentally friendly boiler water treatment agent.

[0036] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0037] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a polyamine boiler water treatment agent, characterized in that: The following steps are involved: Firstly, N-oleyl-1,3-propylene diamine is dissolved in cyclohexylamine, and then water is added to obtain a polyamine boiler water treatment agent.

2. The method for preparing the polyamine boiler water treatment agent according to claim 1, characterized in that: The processing temperature is 30-40°C.

3. The method for preparing the polyamine boiler water treatment agent according to claim 1, characterized in that: The concentration of N-oleyl-1,3-propylene diamine is 10-15 g / L.

4. The method for preparing a polyamine boiler water treatment agent according to claim 1, characterized in that: The mass ratio of N-oleyl-1,3-propylenediamine / cyclohexylamine is 1:(1-2.5).

5. A polyamine boiler water treatment agent prepared by the method according to any one of claims 1 to 4.

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