JP2003083689A - Rotary regenerative heat-exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotary regenerative heat-exchanger provided with members, such as heat-transfer element, in which heat resistance is enhanced, and simplification in production processes and effect on environment can be improved, without degradation of excellent corrosion-resistance of conventional enamel. SOLUTION: This heat exchanger is constituted of a rotation center-shaft 1, a rotor 2, a partition 3, a basket, a heat-transfer element in the basket, and a seal in the radial direction, extending axially along the edge of the partition 3. In the heat exchanger, any one of the heat-transfer elements, the basket, the partition 3, and the axially extending seal is covered with an enamel comprising 50-60 wt.% of SiO2 +ZrO2 +TiO2 , 10-20 wt.% of Al2 O3 +B2 O3 , 10-15 wt.% of Na2 O+K2 O+Li2 O, 10-15 wt.% of CaO+BaO+SrO, and 1.5-5.0 wt.% of FeO+ CoO+NiO+CuO.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a rotary regeneration heat exchange device.

[0002]

2. Description of the Related Art Generally, as shown in FIGS. 1 to 4, a rotary regeneration type heat exchange device has a rotation center axis 1, a rotor 2 rotating around the rotation center axis 1, and a radius inside the rotor 2. A plurality of partitions 3 extending in the direction, a basket 4 housed between the partitions 3, a heat transfer element 5 loaded in the basket 4, and a plurality of radial directions extending along the axial edge of the partition 3. It is composed of a seal 6 and a housing 7 which houses the rotor 2 and has an inlet duct 7a and an outlet duct 7b for introducing a heating fluid and a fluid to be heated into the rotor 7, rotating the rotor 2 and connecting the heat transfer element 5 to the rotor 7. The heat exchange between the heating fluid and the fluid to be heated is performed via the above. Reference numeral 8 denotes a sector plate which separates the heating fluid (high temperature fluid) side and the heated fluid (low temperature fluid) side.

When the heating fluid is an exhaust gas obtained by burning a fuel containing sulfur during the operation of the rotary regeneration heat exchanger, sulfuric acid is condensed in the low temperature portion of the rotor 2 shown in FIG. Therefore, so-called low temperature corrosion occurs. Also, when the fuel is natural gas, water condensation occurs in the low temperature part,
The condensed water has a low pH containing chloride ions and sulfate ions.
Since it is water, so-called water corrosion occurs. Due to these low temperature corrosion and water corrosion, there are problems in that the heat transfer element 5 is particularly worn, the thermal efficiency is lowered, and the pressure loss is increased due to corrosion products. As a material for the heat transfer element 5 used in the low temperature part, the conventional corrosion resistant steel
An enamel-coated steel having about 0 times the corrosion resistance was used.

However, due to the diversification of the operation of recent power plants, an operation pattern of occasionally stopping the operation is introduced. In addition to the low temperature corrosion during the continuous operation as described above, the heat transfer element and Corrosion often occurred in each member (basket, partition, radial seal, etc.).

Corrosion during shutdown is caused by water, and is often due to dew point condensation of atmospheric moisture in the rotary regeneration heat exchanger and moisture absorption of adhering dust during operation. The increase in the number of washings also has an effect. As described above, since the enamel-coated steel is used in the low temperature part of the heat transfer element 5 of the conventional rotary regeneration heat exchanger, corrosion during stoppage does not cause a problem including washing, but Medium temperature and high temperature parts where low temperature corrosion due to exhaust gas does not occur (Fig. 2
In (see), since metal materials including corrosion resistant steel are used, rust occurs in the middle temperature part and the high temperature part during the stop. In particular,
The rust generated on the heat transfer element becomes strong floating rust by drying and heating, narrowing the fluid flow path, and the pressure loss rises abnormally at the next startup more than the loss of material.
There was a great danger.

[0006]

Corrosion resistance of the heat transfer element 5 in the middle and high temperature parts can be ensured by using the enamel coated steel, but the conventional corrosion resistant enamel coated steel has a limit of heat resistance, The application was at most up to a member located in the middle of the middle temperature part of the heat exchange device (a little less than 300 ° C.), and the high temperature side of the middle temperature part and the high temperature part (that is, 300 ° C. or higher) were deteriorated by long-term use. This is because the amplitude of the temperature change with respect to the material due to heat exchange causes microcracks in the enamel layer to start deterioration, but this is not a problem from the viewpoint of high-temperature oxidization, but it does not cause condensed moisture or corrosive In the case of environment, the base material is attacked to promote the progress of deterioration. Further, in the middle temperature part, the low temperature side is often a low temperature corrosion region, and in particular, the enamel of the middle temperature part needs heat resistance on the high temperature side and corrosion resistance equivalent to that used on the low temperature part on the low temperature side. Further, in the case of a special enamel firing, the productivity is lowered and the cost becomes high, so that an enamel material capable of maintaining the quality by the conventional firing method is required.

The present invention has been made in order to meet the above-mentioned conventional requirements, and the purpose thereof is to significantly improve heat resistance without impairing the excellent corrosion resistance of conventional enamel. It is an object of the present invention to provide a rotary regeneration heat exchange device equipped with a member such as a heat transfer element capable of greatly simplifying the production process and significantly improving the influence on the environment.

[0008]

SUMMARY OF THE INVENTION A rotary regeneration heat exchange apparatus according to the present invention comprises a rotation center axis, a rotor rotating about the rotation center axis, and a plurality of partitions extending in the radial direction of the rotor. A basket housed between the partitions, a heat transfer element loaded in the basket, a plurality of radial seals extending along an axial edge of the partition, the rotor containing the heating fluid and the heated fluid. A rotary regenerative heat exchange, which comprises a housing having an inlet duct and an outlet duct for guiding a fluid, rotates the rotor, and exchanges heat between a heating fluid and a heated fluid via the heat transfer element. In the device, at least one of the heat transfer element, the basket, the partition, and the radial seal is coated with an enamel, and the weight of the chemical composition of the enamel is increased. _Ratio, SiO 2 + _ZrO 2 + Ti
O ₂ is 50 to 60%, Al ₂ O ₃ + B ₂ O ₃ is 10 to 2
0%, Na ₂ O + K ₂ O + Li ₂ O 10 to 15%, C
aO + BaO + SrO 10 to 15%, FeO + CoO
+ NiO + CuO is characterized by being composed of 1.5 to 5.0%. Further, in the above apparatus, the temperature at which the compressive stress formed in the enamel coating changes into a tensile stress by heating is 350 ° C. or higher.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. As described above, since the corrosion resistance is sufficiently ensured in the conventional enamel-coated steel, in the present invention, the chemical composition of the enamel (also referred to as frit component) is adjusted to improve the heat resistance without impairing the corrosion resistance. went. Table 1 shows a comparison between the conventional enamel and the enamel of the present invention.

[0010]

[Table 1]

The above-mentioned SiO ₂ + ZrO ₂ + TiO ₂ is a main component of enamel, is a component which improves chemical durability and imparts heat resistance. SiO ₂ + ZrO ₂ + Ti
Of O ₂ , SiO ₂ is 85 to 95% and ZrO ₂ is 0 to
5%, TiO ₂ is 0 to 10%. SiO ₂ + ZrO
_{When 2} + TiO ₂ is 50% or less, the chemical durability is poor, and when it is 60% or more, it becomes insoluble and becomes difficult to be fired.

The Al ₂ O ₃ + B ₂ O ₃ is a component that affects the corrosion resistance and the easy solubility of the enamel. Al ₂ O ₃
Of _{+ B 2 O 3, Al 2} O 3 is _0~5%, B 2 _{O 3} is 95 to 100%. Al ₂ O ₃ + B ₂ O ₃ is 10%
When it is below, the enamel becomes poorly soluble and becomes difficult to be fired, and when it is at least 20%, the corrosion resistance becomes poor.

The Na ₂ O + K ₂ O + Li ₂ O is a component that affects the corrosion resistance, the easy solubility and the thermal expansion coefficient of the enamel. Of Na ₂ O + K ₂ O + Li ₂ O, Na
₂ O is 80 to 90%, K ₂ O is 0 to 5%, Li ₂ O is 1
It is 0 to 20%. Na ₂ O + K ₂ O + Li ₂ O is 10
% Or less, the enamel becomes poorly soluble and difficult to fire,
If it is 15% or more, the coefficient of thermal expansion becomes large, and the compressive stress formed in the enamel coating is made small to lower the heat resistance. Also, the corrosion resistance is reduced.

The CaO + BaO + SrO is the Na
_{2 O + K 2 O + Li} 2 O and is a component which acts similarly _to a slow work than _{Na 2 O + K 2 O +} Li 2 O. Of CaO + BaO + SrO, CaO is 90-9
5%, BaO is 0 to 10%, and SrO is 0 to 5%.
When CaO + BaO + SrO is 10% or less, the easy solubility is insufficient and it becomes difficult to fire, and when it is 15% or more, the corrosion resistance decreases.

The above FeO + CoO + NiO + CuO is
It is a component that ensures the adhesion of enamel. FeO + Co
Of O + NiO + CuO, FeO is 0 to 20%, Co
O is 10 to 90%, NiO is 10 to 90%, and CuO is 0.
~ 50%. If FeO + CoO + NiO + CuO is 1.5% or less, the adhesiveness cannot be secured, and if it is 5% or more, a metal component is deposited on the enamel surface and corrosion resistance is deteriorated.

In this embodiment, in order to improve the heat resistance, the coefficient of thermal expansion is reduced so that the compressive stress in the enamel layer remains at a higher temperature. for that reason,
The content of the alkaline component (Na ₂ O + K ₂ O + Li ₂ O) was reduced from about 25% of the conventional content to about 10% or more. Since it was found that the firing temperature rises due to the reduction of the alkaline component, the alkaline earth component (CaO + BaO + Sr
O) was increased from about 5% of the conventional composition to about 10% to suppress the increase of the firing temperature which affects the productivity. Further, as the heat resistance was improved, it was feared that the adhesiveness, which is one of the important factors as the enamel-coated steel, would be lowered. Therefore, the amount of metal oxide (FeO + CoO + NiO + CuO) was increased to secure the adhesiveness.

As described above, the adjusted frit is formed, and its thermal expansion characteristics and the strain-free point (the stress in the enamel layer formed by the difference in thermal expansion between the base metal and the enamel layer becomes zero). The results of measuring the temperature are shown in Table 2. Table 2
As is clear from the above, the enamel of this example showed a remarkable effect in the coefficient of thermal expansion and the strain-free point as compared with the conventional enamel.

[0018]

[Table 2]

Next, this frit was put into a ball mill at the weight ratio shown in Table 3, crushed to obtain a glaze, and the degreased steel sheet was glazed and baked at 810 to 850 ° C. for 3.5 minutes. Then, a test piece was prepared, and the following performances were compared with the conventional enamel-coated steel.

[0020]

[Table 3]

Corrosion resistance (sulfuric acid resistance) test [Test material: 100 m
m × 100 mm, film thickness of about 200 μm, corrosion loss due to sample number (n) = 3 under each condition 1) 50% H ₂ SO ₄ , 70 ° C. (dew point condensation vapor-liquid equilibrium point)
120 hours 2) 1% H ₂ SO ₄ , boiling 2 hours 3) 30% H ₂ SO ₄ , boiling 18 hours 4) 50% H ₂ SO ₄ , boiling 18 hours

[0022]

[Table 4]

Regarding sulfuric acid resistance, there was no difference between the conventional enamel and the enamel of the present invention, and it was confirmed that the enamel has excellent corrosion resistance as compared with sulfuric acid corrosion resistant steel.

Heat resistance test [Material: 100 mm x 100 m
m, film thickness of about 200 μm, number of samples at each temperature (n) =
3] In an electric furnace, a temperature amplitude of ± 10 ° C. (a temperature amplitude of an element accompanying the rotation of the rotary regeneration heat exchange device) was given in a cycle of 1 minute (a rotary regeneration heat exchange device of 0.5 rpm) and a center temperature of 250. ~ 370 ° C was carried out in 10 ° C steps. 1) In the conventional enamel, fine cracks were observed at 290 ° C or higher at about 3,000 hours. 2) The enamel of the present invention has a temperature of 350 ° C. or higher and about 3,000.
Minute cracks were observed over time. When conventional enamel was exposed to a temperature of slightly less than 300 ° C. for 3,000 hours (temperature amplitude ± 10 ° C.), fine cracks were observed on the surface of the enamel, whereas in the enamel of the present invention, at 350 ° C. or higher under the same conditions. For the first time, minute cracks were observed on the surface of the enamel, and the heat resistance was clearly improved. This also shows that the temperature at which the enamel changes from tension to compression is sufficiently higher than that of conventional enamel in the deformation test of the enamel plate due to the difference in thermal expansion in the one-sided enamel firing described in the next section.

Deformation of the enamel plate due to the difference in thermal expansion during single-sided enamel firing [Test material: 50 mm × 10 mm, film thickness about 200 μm] 1) Conventional enamel changes from tension to compression at about 250 ° C. . 2) The enamel of the present invention changes from tension to compression at about 390 ° C.

Thermal shock test [Sample material: 100 mm × 100
mm, film thickness about 200 μm, number of samples at each temperature (n)
= 3] In an electric furnace, heat to water temperature + test temperature for 10 minutes or more, and put into water all at once. The test temperature is 300 to 500 ° C in increments of 50 ° C. Each temperature was repeated 10 times. 1) With conventional enamel, it was observed that the surface became rough and the gloss decreased at 400 ° C or higher. 2) With the enamel of the present invention, it was observed that the surface of the enamel was rough and the gloss was decreased at 400 ° C or higher.

The enamel of the present invention has no difference in pinhole, adhesion (PEI method), chipping and thermal shock resistance from the conventional enamel, or is equal to or more than that of the conventional enamel, and it is recognized that knuckles and copper heads are generated. Moreover, it was not necessary to raise the firing temperature of the enamel.

[0028]

1) According to the present invention, the corrosion-resistant heat-resistant enamel coated steel capable of significantly improving the heat resistance without impairing the excellent corrosion resistance of the conventional enamel is used in the rotary regeneration heat exchanger at low temperature. It is now possible to apply enamel-coated steel that has only heat resistance and corrosion-resistant enamel-coated steel to the entire temperature range of each member such as heat transfer element, basket, partition, radial seal, etc. . 2) In the productivity of each member such as the heat transfer element of the rotary regeneration type heat exchange device of the present invention, the pickling and neutralization treatment steps of the base material, which were indispensable in the conventional enamel-coated steel, are not required. Since the treatment process can be performed without pickling, the process simplification and environmental impact have been greatly improved.

[Brief description of drawings]

FIG. 1 is an overall view of a rotary regeneration heat exchange device.

FIG. 2 is an explanatory diagram of a rotor of the device.

FIG. 3 is an explanatory view of a basket of the device.

FIG. 4 is an explanatory view of a heat transfer element of the device.

[Explanation of symbols]

1 rotation center axis 2 rotor 3 partitions 4 baskets 5 Heat transfer element 6 radial seal 7 housing 7a Entrance duct 7b Exit duct 8 sector plates

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tadashi Noguchi             2-3-4 Nakamachi, Minatojima, Chuo-ku, Kobe             Rust Power Co., Ltd. (72) Inventor Rihei Hamada             2-1-2 Oyodokita, Kita-ku, Osaka             Hello Co., Ltd. (72) Inventor Fumio Tokunaga             2-3 Nitta-Asahicho, Daito City Japan Industrial Stock Association             In-house

Claims (2)

[Claims] 1. A center of rotation, a rotor rotating about the center of rotation, a plurality of partitions extending in the radial direction of the rotor, and a basket accommodated between the partitions.
A heat transfer element loaded in the basket, a plurality of radial seals extending along an axial edge of the partition, and an inlet duct and an outlet duct for accommodating the rotor and guiding a heating fluid and a heated fluid thereto. A rotary regeneration heat exchange device configured to rotate the rotor and perform heat exchange between a heating fluid and a fluid to be heated via the heat transfer element. , At least one of the partition and the radial seal is covered with enamel, and the weight ratio of the chemical composition of the enamel is SiO ₂ + ZrO ₂
+ TiO ₂ is 50 to 60%, Al ₂ O ₃ + B ₂ O ₃ is 1
_{0~20%, Na 2 O + K} 2 O + Li 2 O is 10 to 15
%, CaO + BaO + SrO 10 to 15%, FeO +
CoO + NiO + CuO consists of 1.5-5.0%, The rotation regeneration type heat exchange apparatus characterized by the above-mentioned. 2. The rotary regenerative heat exchange device according to claim 1, wherein the temperature at which the compressive stress formed in the enamel coating changes into a tensile stress by heating is 350 ° C. or higher.