DE3822874C2 - - Google Patents

Description

The invention relates to a method for producing a Corrosion-resistant protection on fin walls and superheaters pipes in hot gases containing sulfur, temperatures of over 400 ° C are used in incineration plants are.

On fin walls, especially of large combustion plants, for example in thermal power plants, waste incineration plants or the like occur depending on the used liquid, gaseous or solid fuel in the turbu Lenzzone the flame or the fireball strong corrosion appearances.

The emergence of this corrosion attack is on the oxidizing or reducing flame and on the ver different oxides of elements in the flame gases such. B. attributed SO ₂ or CO. To date, the pipes or parts of the fin wall have been cut out at the highly corroded areas and replaced with new parts. When using plasma and wire spraying, such an exchange could be avoided in part or in limited cases. However, these coatings showed unsatisfactorily short service lives or signs of detachment when using an adhesive layer.

Particular difficulties arise due to the size of the other spray systems and those that occur during spraying Noise level that requires working with hearing protection makes. Also the spray to be observed in these processes Distances for applying a constant layer are important Difficult to keep working in boiler systems.

Against the use of autogenous flame spray known per se Brenner had considerable concerns in the professional world, why such devices in the field in question have not been applied.

In view of these circumstances, the inventor has the task posed, the procedure mentioned at the beginning with avoidance to improve the detected defects as well as a corrosion solid protection for fin walls and superheater pipes in sulfurous hot gases by means of good and permanent to set materials.

In the method according to the invention, a Protective layer - preferably from 0.2 to 1.5 mm thick Metal powder atomized from the melt flow with an auto gene flame spray burner with a gas flow rate between about 1000 to 3000 NL / h - advantageously 1500 up to 2500 NL / h - applied for the fuel gas, whereby the Metal powder used the following composition having:

Cr 15% to 35%,
Mn 0.05 to 3%,
Mo 0.05% to 5.0%,
C 0.1% to 3.0%,
Si 0.1 to 3%,
Al 2% to 15% with the rest Fe.

Preferred areas are

Cr 20% to 30%,
Mn 0.1% to 2%,
Mo 0.1% to 4%,
C 0.1% to 2.9%,
Si 0.5% to 2%,
Al 3% to 10%,
Rest of Fe.

For further features, reference is made to the subclaims taken.

The layer has a uniform structure and is without Sprayed on the primer. Due to the homogeneity and the Composition is good in corrosion resistance sulfurous hot gases with a sulfur content of more than 0.2% up to 5%.

The Erfin is used in the description below a preferred embodiment and based on the Drawing explained; this shows in

Figure 1 shows a steep tube boiler in cross section.

Fig. 2 is a schematic representation of the steep tube boiler.

A steep tube boiler 10 for coal firing has a combustion chamber 14 with a burner 15 and a plurality of water tubes 16 on the boiler walls 17 above a deasher 12 . With 18 bulkhead superheater below a Kes seltrommel 20 are designated, with 22 touch superheaters and with 24 feed water preheaters 24 - in which the feed water is preheated with a fuel saving and a reduction in thermal stresses in the boiler with the exhaust gases of the boiler system - are on the right flank of the Fig. 1 arranged air preheater 26 . In those superheaters 18, 22 , saturated steam is brought to a higher temperature, ie superheated, without increasing the pressure.

Fig. 2 shows typical stress zones for corrosion (index k) and erosion (index a). Corrosion is mainly found on the burner 15 _k , on the boiler wall 17 _k and on the bulkhead superheaters 18 _k , the erosion phenomena, however, below the combustion chamber 14 at 13 _a , on the boiler wall at 17 _a , on the soot blower 19 _{a of} the bulkhead superheater 18 , to the first in the flow direction x contact superheaters 22 _a and at the preheater 24 _a. There are also erosions at an upper access opening 30 _a .

The temperatures in the corrosion and oxidation-loaded furnace are approximately between 1000 ° and 1200 ° C (zone A) , in zone B at approximately 700 ° C and in the preheater 24, 26 at approximately 400 ° C (zone C) .

The powdery materials used according to the invention are on the way of Thermal spraying applied to fin walls and superheater tubes that are on surfaces temperatures of far more than 400 ° C are used.

Claims (6)

1. A method for producing a corrosion-resistant protection on fin walls and superheater tubes in sulfur-containing hot gases, which are used in combustion plants at surface temperatures of over 400 ° C, characterized in that a metal powder atomized from the melt flow is applied with an autogenous flame spray gun to form a protective layer is at a gas flow rate between about 1000 to 3000 NL / h for the fuel gas, the metal powder having the following composition: Cr 15.0% to 35.0%,
Mn 0.05% to 3%,
Mo 0.05% to 5%,
C 0.1% to 3%,
Si 0.1% to 3%,
Al 2.0% to 15%,
Rest of Fe. 2. The method according to claim 1, characterized by the use of a metal powder of the following composition: Cr 20.0% to 30.0%,
Mn 0.1% to 2%,
Mo 0.1% to 4%,
C 0.1% to 2.9%,
Si 0.5% to 2%,
Al 3% to 10%,
Rest of Fe. 3. The method according to claim 1 or 2, characterized in that a metal powder with a surface area of more than 200 cm ² / g and / or an aspherical grain shape is used. 4. The method according to any one of claims 1 to 3, characterized in that an autogenous flame spray burner with 1500 to 2500 NL / h is used. 5. The method according to any one of claims 1 to 4, characterized records that a powder amount of 3 to 10 kg / h, preferably 4th up to 8 kg / h. 6. The method according to at least one of claims 1 to 5, characterized characterized in that the layer to a thickness of 0.2 to 1.5 mm is applied.