JP3287243B2 - Oxygen scavenger - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deoxidizer, and more particularly to a deoxidizer capable of efficiently removing dissolved oxygen in water, and particularly effective for preventing corrosion of a boiler system by removing dissolved oxygen in boiler feed water. Related to various oxygen absorbers.

[0002]

2. Description of the Related Art Dissolved oxygen contained in boiler feedwater is:
This constitutes a cause of corrosion of the boiler main body, a heat exchanger, an economizer, a steam condensing pipe, etc. disposed in a stage preceding the boiler main body. Therefore, in order to prevent the corrosion of these boiler systems, it is necessary to remove the dissolved oxygen in the boiler feed water by performing a deoxygenation treatment on the boiler feed water used.

[0003] Therefore, chemical treatment and physical treatment have been conventionally performed as deoxygenation treatment. For example, as a chemical treatment, a method of adding hydrazine (N ₂ H ₄ ) and sodium sulfite (Na ₂ SO ₃ ) to a boiler feedwater as a deoxidizer has been widely adopted.

[0004]

However, in the above-mentioned chemical treatment, the method using hydrazine or sodium sulfite as an oxygen scavenger has the following problems.
First, hydrazine is regarded as a problem in terms of safety for the human body. Further, in the case of sodium sulfite, the following problem occurs because the reaction rate with oxygen is too high.

That is, prior to the addition to the boiler feed water,
When dissolving sodium sulfite in water in the dissolution tank,
The sodium sulfite reacts with the dissolved oxygen to cause a decrease in the concentration thereof, resulting in an insufficient injection amount, which ultimately promotes the corrosion of the boiler system. Furthermore, since sulfuric acid ions are newly generated in the boiler feedwater treated with sodium sulfite, corrosion and scale adhesion are likely to occur in the boiler system.

Therefore, the method using hydrazine or sodium sulfite as the oxygen scavenger is not necessarily industrially advantageous. The present invention solves the above-described problems in the conventional oxygen absorber used when performing deoxidation of boiler feedwater by chemical treatment, for example, and can efficiently remove dissolved oxygen in boiler feedwater, and can provide high safety. The purpose of the present invention is to provide a new oxygen scavenger having a property.

[0007]

In order to achieve the above-mentioned object, in the present invention, a compound having an N-substituted amino group is provided.
An oxygen scavenger characterized by comprising a heterocyclic compound as an active ingredient is provided .

[0008]

[0009]

[0010]

[0011]

[0012]

[0013]

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION The oxygen scavenger of the present invention is preferably one containing the following heterocyclic compound as an active ingredient. That is,

[0015]

[0016]

[0017]

Embedded image

These heterocyclic compounds may be used alone or in combination of two or more. Further, the oxygen scavenger of the present invention has an NN bond in the ring.
(Hereinafter, referred to as heterocyclic compound A)
U), the following equation:

Embedded image (Where a and b are each an integer of 0 to 5,
And an integer satisfying the relationship 2 ≦ a + b ≦ 5 )
(Hereinafter, referred to as heterocyclic compound B)
U), the following equation:

Embedded image (Wherein R ₁ , R ₂ , R ₃ , and R ₄ are different even if they are the same.
May be hydrogen or lower alkyl having 1 to 8 carbon atoms
Represents any group or aryl group, X is hydrogen,
Amino group, alkylamino group having 1 to 8 carbon atoms or diamino
Alkylamino group or lower alkyl having 1 to 8 carbon atoms
Double represented by represents any one group or aryl Le group)
A cyclic compound (hereinafter, referred to as a heterocyclic compound C),
Azodicarbonamide (NH ₂ CON = NCON
One or two or more of selected from the group consisting of H ₂₎
The compound can be used in combination with an oxygen absorber as an active ingredient.
good. In this case, the heterocyclic compound A is the following heterocyclic compound
The compounds are preferred. That is,

Embedded image And, as the heterocyclic compound B,
It can be a preferred example.

Embedded image Further, as the heterocyclic compound C, the following compounds are preferable.
This can be a case in point.

Embedded image

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

The amount of each of the active ingredients listed above is not particularly limited since it is appropriately determined according to the amount of dissolved oxygen in the target water. 0.001 to 1000 mg, preferably 1 to 30
Desirably, it is 0 mg.

[0027]

EXAMPLES Examples 1 to 11 The effects of the oxygen scavenger of the present invention were confirmed as follows. Softened water saturated with oxygen in the air at room temperature was supplied to a 5-liter steam generation test autoclave and operated under the following conditions to generate steam.

Temperature: 185 ° C., pressure: 1 MPa, evaporation amount:
12 liters / hr, blow rate: 10% The generated steam was completely condensed, and the concentration of dissolved oxygen in the obtained condensed water was measured using a dissolved oxygen meter. This value is used as data of Comparative Example 1. Next, a deoxidizer was added to the feed water to generate steam under the same conditions, and the concentration of dissolved oxygen in the condensed water of the steam was measured. Then, the difference from the data of Comparative Example 1 was calculated as the removal amount, and the removal amount was compared with that of Comparative Example 1.
Was calculated as the removal rate (%).

As for the addition of the oxygen scavenger to the feed water, the heterocyclic compound shown in Table 1 was dissolved in the softened water to prepare an aqueous solution having a predetermined concentration, and the aqueous solution was added to the feed water by a constant-rate pump. The concentration of the heterocyclic compound in the feed and feed water was adjusted as shown in Table 1. Table 1 shows the above results.

[0030]

[0031]

[0032]

[Table 1]

[0033]

[0034]

[0035]

[0036]

[0037]

[0038]

[0039]

[0040]

As apparent from the above description, <br/> oxygen scavenger of the present invention can be in the water dissolved oxygen efficiently removed. In particular, when used as a deoxidizer for boiler feedwater, corrosion of the boiler body and steam condensing system piping due to dissolved oxygen can be prevented, and its industrial value is extremely large.

[0041]

────────────────────────────────────────────────── ─── Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C02F 1/58, 1/72 C23F 11/14 C07D 239/54 C07D 213/73 F22D 11/00 JICST file ( JOIS) CA (STN)

Claims (1)

(57) [Claims] 1. An oxygen scavenger comprising a heterocyclic compound having an N-substituted amino group as an active ingredient.