JP2772156B2 - Fuel additive for high temperature oxidation and high temperature corrosion prevention - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel additive for preventing high-temperature oxidation and high-temperature corrosion of a combustor or a moving / static blade contacting a combustion gas of a gas turbine.

[0002]

2. Description of the Related Art The temperature of a gas at the inlet of a recent industrial gas turbine of high efficiency represented by a combined cycle plant has risen significantly to 1300 ° C. or more. The heat-resistant alloys used in gas turbines have been vigorously researched and developed, and the allowable service temperature thereof has been increasing year by year. For this reason, thin air cooling blades are used in actual gas turbines.

On the other hand, the fuels used are LNG, by-product gas, and heavy oil. Recently, studies have been made to utilize coal by liquefaction or gasification. Therefore, it is necessary to prevent high-temperature oxidation and high-temperature corrosion of air cooling blades. For the purpose, coating of alloys such as NiCoCrAlY and CoCrAlY is performed by low-pressure plasma spraying method (Shoji Nakamori, "Corrosion protection")
1989 Proceedings).

Further, in order to reduce the surface temperature of the air cooling blade,
TBC (Thermal Barrier Coating Thermal Barrier Coating)
The application of is also being studied.

[0005] Further, when burning heavy oil containing a large amount of S, Na, V, etc., a Na-VO compound (eg, 5N) which has a low melting point and causes accelerated oxidative corrosion (vanadium attack).
_{a 2 O · V 2 O 4} · 11V 2 O 5, mp 535 ℃) fuel additive mainly composed of MgO or Mg (OH) ₂ in order to prevent the formation of sometimes used.

[0006]

In a high temperature gas turbine, the moving and stationary blades that come into direct contact with the combustion gas increase in oxidation rate and corrosion rate as the gas temperature increases.
Even when the above-mentioned corrosion-resistant coating is performed, a situation has appeared in which a very small amount of corrosive components such as S, NaK, and Cl are introduced into the fuel or combustion air to cause significant corrosion damage.

Further, the use of TBC has a drawback that the ceramic coating layer is easily peeled off, and there are many problems for practical use.

[0008] Mg-based additives also prevent the formation of Na-V-O-based compounds.
There is no effect of preventing high-temperature corrosion caused by formation of Na ₂ SO ₄ and K ₂ SO ₄ by Na, K, Cl and the like.

The present invention has been made in view of the above-mentioned state of the art, and aims to provide a fuel additive for preventing high-temperature oxidation and high-temperature corrosion, which is free from the problems as in the prior art.

[0010]

According to the present invention, there is provided (1) a method comprising mixing a mixture of Al ₂ O ₃ , MgO, CaO and Fe ₂ O ₃ with yttria-stabilized zirconia, yttria partially-stabilized zirconia, CeO ₂ and HfO ₂ . A fuel additive for preventing high-temperature oxidation and high-temperature corrosion, which is obtained by adding and mixing one or more components selected from the group consisting of:

(2) Al (OH) ₃ , Mg (OH) ₂ ,
A mixture of Ca (OH) ₂ and Fe ₂ O ₃ is mixed with yttria-stabilized zirconia, yttria partially stabilized zirconia, CeO ₂ and HfO _2.
A fuel additive for preventing high-temperature oxidation and high-temperature corrosion, comprising a mixture of at least two or more kinds of components.

(3) Al (R-COO) ₃ , Mg (R-
COO) ₂ , Ca (R—COO) ₂ (where R is a chain hydrocarbon residue) and a mixture of Fe ₂ O ₃ , a mixture of yttria-stabilized zirconia, yttria partially-stabilized zirconia, CeO ₂ and HfO ₂ A fuel additive for preventing high-temperature oxidation and high-temperature corrosion, which is obtained by adding and mixing one or more components selected from the group consisting of: It is.

[0013] The fuel additive of the present invention is Al_TwoO_Three, Mg
O, CaO and Fe_TwoO_ThreeOr Al (OH)_Three, Mg
(OH)_Two, Ca (OH)_TwoAnd Fe_TwoO_ThreeOr Al
(R-COO)_Three, Mg (R-COO)_Two, Ca (R-
COO)_Two(However, R is a chain hydrocarbon residue) and Fe_Two
O_ThreeInto a mixture of yttria-stabilized zirconia (hereinafter, referred to as
YSZ), yttria partially stabilized zirconia (hereinafter referred to as YSZ)
Below, PSZ), CeO _TwoAnd HfO_TwoAdd and mix
After that, use a surfactant for oily components such as light oil or water.
Obtained by dispersing using

Al ₂ O ₃ , MgO, CaO and Fe ₂ O
A mixture of ₃ and YSZ, PSZ, when the proportion of one or more components selected from the group consisting of CeO ₂ and HfO ₂ representatively taken up and explained, the former: the latter is 90 to 97 wt%: 10-3 %, Preferably in the former mixture, Al ₂ O ₃ , MgO, CaO and Fe ₂ O ₃
Of Al ₂ O ₃ : 40 to 50% by weight, MgO: 10
-25% by weight, CaO: 20-35% by weight, Fe
₂ O ₃ : The range of 2 to 5% by weight is preferred.

Al ₂ O ₃ , MgO, CaO and Fe ₂ O
Instead of ₃ , Al (OH) ₃ , Mg (OH) ₂ , Ca
_{(OH) 2, Fe 2 O} 3 or _{Al (R-COO) 3,} M
_{g (R-COO) 2,} Ca (R-COO) 2, Fe 2 O
_{Also when 3} is used, it is preferable that each of them is in the above range in terms of oxide.

[0016]

The mixture of Al ₂ O ₃ , MgO, CaO and Fe ₂ O ₃ is mixed with YSZ, PSZ, CeO ₂ and HfO ₂
The mixture obtained by adding and mixing one or more components selected from the group consisting of
It collides with the stationary blade and adheres together with Na ₂ SO ₄ in the combustion gas.

Al ₂ O ₃ , MgO, CaO, Fe ₂ O ₃
Melting points of 2050 ° C., 2800 ° C., and 2600 ° C., respectively.
℃, 1550 ℃, gas turbine blades are 90
Since it is cooled to 0 ° C. or less, it solidifies, prevents contact between the combustion gas and the blade surface, exhibits the same effect as TBC, and can reduce the temperature of the blade surface by 50 to 100 ° C. (As a result, the corrosion rate depending on the exposure temperature is greatly reduced.)

[0018] By proceeding corrosion of blade material by deposits in Na ₂ SO ₄ are usually the following (1) to (3) reactions such as formulas (hot sulfurization reaction), the majority of the deposits Al ₂ O
_{3, MgO, CaO, Fe 2} O 3, YSZ, PSZ, C
Since it is an oxide such as eO ₂ or HfO ₂ , Na ₂ SO
₄ prevents direct contact with the wing material, preventing the progress of corrosion. _{Na 2 SO 4 + 3M → Na} 2 O + 3MO + S (1) M + S → MS (2) Na 2 SO 4 + 3MS → Na 2 O + 3MO + 4S (3) ( however, M represents Fe, a metal such as Ni.)

When Na ₂ SO ₄ in the deposit is locally in contact with the wing material and S is generated according to the formula (1), or when sulfur compounds in the combustion gas such as SOx enter the deposit and the S partial pressure is increased. Is higher, Y ₂ O ₃ and CeO in YSZ and PSZ
₂ , HfO ₂ reacts with S as in the following formula, and prevents S from reacting directly with the wing material. Y ₂ O ₃ +1/2 (S) +2/3 (Cr) → Y ₂ O ₂ S _0.5 + 1/3 (Cr ₂ O ₃ ) (4) CeO ₂ +1/2 (S) + 2 / 3 (Cr) → CeOS _0.5 + 1/3 (Cr ₂ O ₃ ) (5) HfO ₂ + 1/2 (S) + 2/3 (Cr) → HfOS _0.5 + 1/3 (Cr ₂ O ₃ ) ( 6)

[0020] Even when the deposit layer adhered to the blade surface is peeled off due to a temperature change or other causes, a new additive component contained in the combustion gas adheres and repairs the deposit layer.

As described above, the basic mixture is composed of Al ₂ O ₃ , MgO,
The operation of CaO and Fe ₂ O ₃ has been described, but the basic mixture is Al (OH) ₃ , Mg (O
_{H) 2, Ca (OH)} 2, Fe 2 O 3 or Al (R-C
OO) ₃ , Mg (R-COO) ₂ , Ca (R-COO)
_{In the case of 2} and Fe ₂ O ₃ , hydroxides and organic compounds in the mixture become oxides at high temperatures, so that their actions are the same.

[0022]

【Example】

(Example 1) Al ₂ O ₃ : 40%, MgO: 25%, Ca
_{O: 20%, Fe 2 O} 3: 5%, YSZ: After miniaturized to a particle size of about 1μ in 10% mixture grinder using a non-ionic surface active agent is dispersed into kerosene additive and did.
(The weight ratio of the mixture / kerosene was 35/65.) Using this additive, a combustion corrosion test was performed with an air-cooled test piece under the conditions shown in Table 1. The test method was performed as follows.

Using an air-cooled test piece by a combustion type corrosion test apparatus, a corrosion test was conducted in an environment simulating heavy oil combustion gas. The gas temperature in the test section was set at 1200 ° C as a target, and the metal temperature of each test piece was 830 ° C.
Was adjusted. The test time was 300 hours including two start-ups and stoppages (every 100 hours). S which is a corrosive component,
Na and V are SO ₂ gas, 0.5% NaVO ₃ aqueous solution,
A 0.5% VOSO ₄ aqueous solution was used to inject S = 0.5% and Na = 1 ppm corresponding to the amount of fuel kerosene from the tip of the burner. Further, the additive according to the present invention was added at a ratio of 1/100000 to kerosene using fuel as a fuel.
The results are shown in Table 1 below.

Example 2 Al ₂ O ₃ : 50%, MgO: 1
0%, CaO: 30%, Fe 2 O 3: 5%, PSZ: 5
% Mixture was prepared in the same manner as in Example 1, and the same corrosion test was performed. The results are shown in Table 1.

(Example 3) Al ₂ O ₃ : 40%, MgO: 2
0%, CaO: 30%, Fe 2 O 3: 5%, CeO 2:
A 5% mixture was prepared in the same manner as in Example 1 and subjected to the same corrosion test. The results are shown in Table 1.

Further, in place of Al ₂ O ₃ , MgO, CaO and Fe ₂ O ₃ , respective hydroxides such as Al
(OH) ₃ , Mg (OH) ₂ , Ca (OH) ₂ and Fe
₂ O ₃ , organic compound such as Al (R—COO) ₃ , M
_{g (R-COO) 2,} Ca (R-COO) 2 and Fe ₂
Using O ₃ , the converted value of oxide is Al ₂ O ₃ : 40 to 5
0% by weight, MgO: 10 to 25% by weight, CaO: 20 to
Even as an additive that satisfies 30% by weight and Fe ₂ O ₃ : 2 to 5% by weight, these hydroxides and organic compounds are changed into respective oxides by combustion, so the oxides of the above examples were used. It has the same effect as in the case.

As a result of the above embodiment, the following effects were obtained. (1) Reduction of corrosion amount Table 1 shows a corrosion test using the additive according to the present invention and a test of no additive injection and a test of injection of a commercially available magnesium-based additive (main component: 35% MgO) performed for comparison. Although the results are shown, the amount of corrosion tends to increase with the commercially available additive as compared with the case without the additive, whereas in the present invention, the corrosion weight loss can be reduced to 1/10 or less.

[Table 1] Note 1) Test material: IN738LC (Ni-8.3Co-1)
6Cr-2.5W-3.4Al-3.4Ti-1.7T
a-1.7Mo-0.1C) Note 2) Corrosion weight loss and maximum erosion depth are 10 without additive.
The relative values were set to 0.

(2) Attachment of additive components In the present invention, 0.5-0.5
While a light brown deposit of about 1.0 mm was attached, most of the white deposits were dropped off with commercial additives,
It was confirmed that the adhesion of the deposit according to the present invention was excellent. In addition, black to black-green deposits were attached without additives, indicating that the deposits were molten during the test.

(3) Absorbing effect of S by the attached matter The attached matter attached to the test piece is separately collected into an upper layer (gas side) and a lower layer (test piece side), and a chemical analysis is performed. The distribution was examined with an X-ray microanalyzer. From the results of chemical analysis of the deposit, the deposit of the present invention was 1-2% S (as SO ₃ ) in both the upper and lower layers, whereas the deposit with the commercial additive was 0.5% S in the upper layer.
(As SO ₃ ), the lower layer 5% S (as SO ₃ ) and the lower layer had concentrated S content.

Further, from the results of elemental analysis of the cross section, it was confirmed that the S component penetrated into the alloy and a corrosion reaction occurred with the commercially available additive as in the case without the additive. On the other hand, in the present invention, although the formation of oxide is recognized on the alloy surface layer, the S component is not detected, and the S component is absorbed by the additive attached to the present invention, thereby preventing the S component from reaching the alloy. It was confirmed that.

(4) Decrease in test piece surface temperature As described above, a deposit of 0.5 to 1.0 mm adheres to the test piece surface, and when the heat insulating effect is calculated, the test piece surface temperature shows no deposit. Lower by 50 to 100 ° C. Since the corrosion rate at a high temperature usually increases exponentially with an increase in temperature, this decrease in the specimen surface temperature has a great effect on reducing the corrosion rate.

(5) Adhesion of attached matter
As a result of examining the ratio of ₂ O ₃ / MgO / CaO,
The result as shown in FIG. 1 was obtained. FIG. 1 shows (MgO + Ca
O) / Al ₂ O ₃ ratio = 0 (that is, Al ₂ O ₃ : 10
MgO / CaO, (MgO + CaO) / Al ₂ O ₃
The peeling degree at the time of the ratio is shown by the corresponding area.

FIG. 1 shows that the MgO / CaO ratio is 0.7-1.
The degree of peeling is small at about 4, while (MgO + CaO) / A
l ₂ O ₃ ratio is found to be less peeling degree of about 0.5 to 1.5. This indicates that the ratio of Al ₂ O ₃ : MgO: CaO is preferably about 2: 1: 1.

On the other hand, the content of Fe ₂ O ₃ is adhesion increases with increase in the content as shown in FIG. 2, approximately allowable at about 2% (extreme adhesion in degrees peeling 20% or more It was confirmed that the adhesion was gradually increased up to 5% and almost saturated with 5% Fe ₂ O ₃ . From this, the addition ratio of Fe ₂ O ₃ is 2 to 5% by weight.
Is preferable. The data in Figure 2 Fe ₂ O
₍₃ ) The area of adhering matter peeling after burning test of 0% content additive is 1
It is a chart showing the relative values as 00.

(6) FIG. 3 shows YSZ, PSZ and Ce.
The relationship between the added amount of O ₂ and HfO ₂ and the extent to which S reaches the alloy is shown. In any case, the added amount of 3% or less indicates that the S in the gas may reach the alloy in a short time. I was On the other hand, at 10% or more, no reaction between the S component and the alloy was observed. Therefore, the mixing ratio of YSZ, PSZ, CeO _2, HfO _2, or the like is 3 to 10% by weight. FIG. 3 shows the relative positions of detected S atoms, where S atoms are detected by EPMA and the total thickness of the attached matter is 100. (Error 5-10%)

[0036]

According to the fuel additive of the present invention, an additive capable of preventing oxidation and corrosion at high temperatures is provided, and its industrial effect is remarkable.

[Brief description of the drawings]

FIG. 1 shows the additive of the present invention (MgO + CaO) / Al ₂ O
₃ is a chart showing the relationship between the ratio ₃ and the MgO / CaO ratio and the degree of peeling.

FIG. 2 is a table showing the relationship between the Fe ₂ O ₃ content of the additive of the present invention and the degree of peeling.

FIG. 3 YSZ, PSZ, CeO ₂ , H of additives of the present invention
4 is a chart showing the relationship between the amount of fO ₂ added and the degree of penetration of S into deposits (and alloys).

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification code FI C10L 10/04 C10L 10/04 (72) Inventor Haruo Otsuka 2-1-1 Shinhama, Arai-cho, Takasago-shi, Hyogo Prefecture Mitsubishi Heavy Industries, Ltd. Takasago In-house (56) References JP-A-62-227096 (JP, A) JP-B-26-6084 (JP, B1) JP-B-47-8452 (JP, B1) (58) Fields investigated (Int. . ^6, DB name) C10L 1 / 12,1 / 18,1 / 30,10 / 04

Claims (3)

(57) [Claims] 1. An Al ₂ O ₃ , MgO, CaO and Fe ₂
A mixture of O ₃ , yttria-stabilized zirconia,
Yttria partially stabilized zirconia, CeO ₂ and HfO
_{2. A} fuel additive for preventing high-temperature oxidation and high-temperature corrosion, wherein one or more components selected from the group consisting of ₂ are added and mixed. 2. Al (OH)_Three, Mg (OH)_Two, Ca
(OH)_TwoAnd Fe _TwoO_ThreeA mixture of
A stabilized zirconia, yttria partially stabilized zirconia
A, CeO_TwoAnd HfO_TwoOne selected from the group consisting of
High temperature acid characterized by adding and mixing the above components
Additive for high temperature corrosion prevention. 3. Al (R-COO) ₃ , Mg (R-COO)
O) ₂ , Ca (R—COO) ₂ (where R: chain hydrocarbon residue) and Fe ₂ O ₃ are mixed with yttria-stabilized zirconia, yttria partially stabilized zirconia,
A fuel additive for preventing high-temperature oxidation and high-temperature corrosion, wherein one or more components selected from the group consisting of CeO ₂ and HfO ₂ are added and mixed.