JPH0148238B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Object of the Invention) Industrial Application Field This invention relates to a refractory heat insulating lining material for heating furnaces used in petroleum refining, petrochemical, and other general chemical plants. Specifically, the object of the present invention is to provide a lining material that is a ceramic fiber refractory heat insulating material provided inside a heating furnace and has sufficient corrosion resistance even against low-quality fuel oil containing a large amount of corrosive components.

Conventional technology Ceramic fiber fireproof insulation materials have many superior properties compared to conventionally used castables (fireproof insulation concrete), such as heat insulation, heat resistance, acid resistance, sound insulation, and light weight. However, it has been widely used in recent years due to its relatively low cost.

The composition of ceramic fibers varies depending on their heat resistance (nominal maximum operating temperature); in the case of heating furnaces used in the fields of oil refining, petrochemistry, and general chemistry, those used on the hot side have a heat resistance of 1260°C to 1260°C. ₁₄₀₀ °C is often used _, and _its main composition is generally about the following: , heat resistance tends to increase as the Al ₂ O ₃ content increases.

Commercially available ceramic fiber molded products include blankets, boards, and wet felts, but blankets are the most widely used because they can be freely changed in shape and are inexpensive.

Problems to be Solved by the Invention However, an unexpected problem occurred in that the blanket-shaped ceramic fiber attached to the heating furnace deteriorated, was damaged, and fell off. This is particularly noticeable when using low-grade fuel such as C heavy oil.

As we investigate the problem, we find that it is contained in the fuel.
It has now been discovered that a mixture of V ₂ O ₅ and Na ₂ SO ₄ is responsible. V ₂ O ₅ − contained in fuel
The amount of Na ₂ SO ₄ varies greatly depending on the origin of the oil;
Even C heavy oil has a content of about 30 to 50 ppm,
Some contain as much as 1200ppm.

The V ₂ O ₅ −Na ₂ SO ₄ in this fuel oil is carried by the combustion gas, adheres to the surface of the ceramic fiber lining material as ash, melts even at low temperatures, and reacts with the ceramic fiber to form the lining material. This is thought to be corroding, and this has been experimentally proven.

The influence of this V ₂ O ₅ -Na ₂ SO ₄ ash varies depending on its composition ratio, but it is constantly supplied by the combustion gas, and over time it accumulates on the heat-receiving surface of the ceramic fiber lining, increasing its concentration. and promotes erosion.

Therefore, when fuel containing a large amount of V ₂ O ₅ -Na ₂ SO ₄ ash is used, corrosion of the ceramic fiber lining of the heating furnace becomes a serious problem.

(Structure of the Invention) Means for Solving the Problems The present invention provides a method for corrosion prevention treatment of ceramic fiber insulation lining materials that solves this problem.

That is, in the present invention, a suspension of alumina or silica is applied to the heat-receiving surface of a heat-insulating lining material made of a ceramic fiber molded product containing 45 to 65% by weight of alumina and 35 to 55% by weight of silica. The suspension is impregnated so that the suspension is 6 mm or more, and the density of the suspension-impregnated part after drying is 0.25 g/cm ³ or more.

The impregnation process of alumina or silica suspension is
This can be done by dipping, coating, spraying, etc. onto the ceramic fiber fireproof heat insulating lining material.

The suspension of alumina or silica used here is made by mixing fine powder of alumina or silica in water for 10 to 20 minutes.
It is preferable to contain about % by weight. This is because if the concentration is too high, the fine powder will not penetrate into the interior and will only adhere to the surface, resulting in peeling.

In addition, the impregnation treatment can be carried out by attaching the ceramic fiber refractory heat insulating lining material to the hot side of the heating furnace and then spraying or coating the alumina or silica suspension. It is also possible to impregnate the above-mentioned suspension in advance and then attach it to the heating furnace. The thickness of the impregnated part should be 6 mm or more, and the density after drying should be 0.25 g/cm ³ or more. The original density of ceramic fiber blanket is 0.16
g/ ^cm3 or less, but the density can be increased by repeating the impregnation and drying of the above suspension, or by temporarily compressing the blanket during the drying process after impregnation.
0.25g/ ^cm3 or more.

Effect By performing such treatment, V ₂ O ₅ −
Even when using fuel containing a large amount of Na ₂ SO ₄ ,
The corrosion resistance of a heat insulating lining material made of a ceramic fiber molded product can be improved.

Test method V ₂ O ₅ was applied on a test piece (20 mm x 30 mm x 25 mm thick) of ceramic fiber insulation lining material.
-Na ₂ SO ₄ (2 types, component ratio 9:1 and 5:5)
Sprinkle 0.1g of powder at 700℃, 830℃, and 930℃
A method was used in which the samples were heated at each temperature for 48 hours.

Example 1 A ceramic fiber blanket with a heat resistance of 1260°C ( _Al2O3 : 47% by weight, _SiO2 : 52% by weight, density: 0.13g/ ^cm3 ) contains 20 _% alumina fine powder (colloidal alumina). The suspension is impregnated with a thickness of 10 mm and compressed so that the density of the suspension-impregnated part after drying is 0.3.
The above test was conducted using test pieces that were adjusted to have a concentration of g/cm ³ . Even after 48 hours, a slag layer with a thickness of 0.5 to 1 mm was formed on the surface of the test piece, which was only slightly corroded. Heating _temperature and _V2O5
-No obvious difference was observed depending on the component ratio of Na ₂ SO ₄ . Further, this condition showed almost no change even after 240 hours had passed.

Example 2 A ceramic fiber blanket with a heat resistance of 1400°C ( _Al2O3 : 60% by weight, _SiO2 : 39% by weight, density: 0.13g/ ^cm3 ) contains 20 _% alumina fine powder (colloidal alumina). The suspension is impregnated with a thickness of 7 mm and compressed so that the density of the suspension-impregnated part after drying is 0.25.
The above test was conducted using a test piece that was adjusted to have a concentration of g/cm ³ . Even after 48 hours, a slag layer with a thickness of 0.5 to 1 mm was formed on the surface of the test piece, which was only slightly corroded. Also, heating temperature and
No particular difference was observed depending on the component ratio of V ₂ O ₅ −Na ₂ SO ₄ .

Example 3 A ceramic fiber blanket with a heat resistance of 1260°C ( _Al2O3 : 47% by weight, _SiO2 : 52% _by weight, density: 0.13g/ ^cm3 ) contains 10% alumina fine powder (colloidal alumina). The suspension is impregnated with a thickness of 25 mm and compressed so that the density of the suspension-impregnated part after drying is 0.35.
The above test was conducted using test pieces that were adjusted to have a concentration of g/cm ³ . Even after 48 hours, the surface of the test piece was only slightly eroded, and a slag layer with a thickness of 0.3 to 0.8 mm had formed. Also heating temperature and
No particular difference was observed depending on the component ratio of V ₂ O ₅ −Na ₂ SO ₄ .

Example 4 A suspension containing 20% silica fine powder in a ceramic fiber blanket ( _Al2O3 : 47% by weight, _SiO2 : 52% _by weight, density: 0.13g/ ^cm3 ) with a heat resistance of 1260°C. The above test was conducted using a test piece that was impregnated with 10 mm thick and compressed so that the density of the suspension-impregnated part after drying was 0.3 g/cm ³ .
Even after 48 hours, a slag layer with a thickness of 0.5 to 1 mm was formed on the surface of the test piece, which was only slightly corroded. No obvious differences were observed depending on the heating temperature or the component ratio of V ₂ O ₅ -Na ₂ SO ₄ . Further, this condition showed almost no change even after 240 hours had passed.

Comparative Example 1 A ceramic fiber blanket (Al ₂ O ₃ : 47% by weight, SiO ₂ : 52% by weight, density: 0.13 g/cm ³ ) having a heat resistance of 1260° C. was used as a test piece to conduct the above test. After 48 hours, severe erosion was observed on the surface of the test piece, and the center had sunk by 4 to 5 mm. heating temperature and
No particular difference was observed depending on the component ratio of V ₂ O ₅ −Na ₂ SO ₄ .

Comparative Example 2 A ceramic fiber blanket (Al ₂ O ₃ : 60% by weight, SiO ₂ : 39% by weight, density: 0.13 g/cm ³ ) having a heat resistance of 1400° C. was used as a test piece to conduct the above test. After 48 hours, severe erosion was observed on the surface of the test piece, and the center had sunk by 3 to 4 mm. heating temperature and
No particular difference was observed depending on the component ratio of V ₂ O ₅ −Na ₂ SO ₄ .

Comparative Example 3 A ceramic fiber blanket with a heat resistance of 1260°C ( _Al2O3 : 47% by weight, _SiO2 : 52% _by weight, density: 0.13g/ ^cm3 ) contains 20% alumina fine powder (colloidal alumina). The above test was conducted using a test piece impregnated with a suspension of 3 mm in thickness so that the density of the suspension-impregnated part after drying was 0.2 g/cm ³ . After 48 hours, severe corrosion was observed on the surface of the test piece, and the center part was
It had caved in by 3mm. Heating temperature and V ₂ O ₅ −
No particular difference was observed depending on the component ratio of Na ₂ SO ₄ .

(Effects of the Invention) As is clear from the above examples, by carrying out the corrosion prevention treatment method of the present invention, the fireproof and heat insulating lining material made of ceramic fiber molded product used in the heating furnace is contained in the fuel oil. There is
Corrosion caused by V ₂ O ₅ −Na ₂ SO ₄ can be effectively prevented.

Claims (1)

[Claims] 1. A suspension of alumina or silica is applied to the heat-receiving surface of a heat-insulating lining material made of a ceramic fiber molded product containing 45 to 65% by weight of alumina and 35 to 55% by weight of silica. A method for preventing corrosion of a heat insulating lining material, which comprises impregnating it to a thickness of 6 mm or more, and making the density of the suspension-impregnated part after drying 0.25 g/cm ³ or more. 2. Claim 1, wherein the ceramic fiber molded product is a ceramic fiber blanket.
The method described in section.