CN107828928A - A kind of hot air duct - Google Patents

Abstract

The invention relates to a hot air pipeline, which includes a steel shell, and a spraying pipe is attached to the inner side of the steel shell. There is a heat insulating layer inside the spraying pipe, and the feature is that the heat insulating layer has an outer heat insulating layer and a middle heat insulating layer. With the inner high-temperature working layer and fiber blanket, the outer heat insulation layer of staggered joints is built on the inner side of the spraying pipe, and the outer heat insulation layer is low-iron lightweight brick; the middle heat insulation layer of staggered joints is built on the outer insulation Inside the heat layer, the middle heat insulation layer is low-iron mullite lightweight brick; the high-temperature working layer with staggered joints is built on the inside of the middle heat insulation layer, and the inner high-temperature working layer is low-creep andalusite brick. The fiber blanket is a high-alumina fiber with a high temperature resistance of 1200°C, and it is placed in the direction of 120˚‑130˚ on the upper part of the outer heat insulation layer. In the longitudinal direction of the outer insulation layer, the middle insulation layer and the high-temperature working layer, 8±2mm expansion joints are set at a distance of 3000±500mm, and the expansion joints are filled with high-temperature high-alumina fibers. When the air temperature of the hot air duct is greater than 1300°C, the body temperature of the steel shell is lower than 100°C.

Description

a hot air duct

technical field

The invention relates to a hot air pipeline.

Background technique

The refractory heat insulation problem of the hot blast duct system is a sign of the energy efficiency of the blast furnace production. European style, Japanese style and domestic improved technology are generally adopted at home and abroad. In the process of ironmaking, more than 30% of the energy is converted by the hot blast stove. Efficiently transferring heat energy to the blast furnace is the key use of the hot blast piping system. Due to the large change rate of reburning line and high thermal conductivity of the heat-insulating refractory material in the existing hot-blast pipeline, the heat dissipation value is high. At present, the average shell temperature of the hot-blast pipeline system of 22 blast furnaces above 4000 cubic meters in China is 170- 180°C, the loss of heat energy is very large, which does not meet the national requirements for green and low-carbon cleanliness. At the same time, due to a series of problems such as damage to the corrugated compensator, red-hot failure of the tube shell, and equipment damage caused by high shell temperature, the efficiency and service life of the hot blast stove are often reduced. Improving the thermal insulation efficiency of refractory materials in the hot air pipeline system is the core of the efficient and safe operation of the hot air pipeline.

Contents of the invention

In order to overcome the above-mentioned shortcomings of the existing hot air duct, the present invention provides a hot air duct with high heat transfer efficiency when the air temperature is greater than 1300°C, and the temperature of the outer steel shell is lower than 100°C.

Technical idea of the present invention

In the metallurgical industry, the hot air pipeline with a wind temperature greater than 1300°C is called an ultra-high temperature hot air pipeline, and the heat energy loss is very large. The present invention mainly reduces the heat energy loss of this hot air pipeline.

Under the premise of meeting the design principles of blast furnace high-temperature hot-blast piping system, the lining structure of hot-blast piping is very important. The refractory materials lining the pipes require low thermal conductivity, high temperature resistance, and low refiring line change rate in order to achieve the purpose of long service life, energy saving and environmental protection of hot air pipes. How to further reduce the surface temperature of the outer shell and reduce the temperature drop of hot blast is a difficult problem in the design of modern blast furnace hot blast piping.

Under the premise of meeting the high temperature working performance of 1300 ℃, the heat insulation efficiency of the refractory material of the hot air pipeline system is improved. Specifically, it refers to the application of low thermal conductivity, low iron mullite, high temperature and non-expansion double-layer ultra-thick heat insulation ring technology in the hot air pipeline system, that is, the double-layer structure of low-iron mullite lightweight bricks is used in the hot air pipeline system. The thickness reaches 300 mm.

The specific method is:

Through the analysis of the heat insulation and refractory materials used in major domestic blast furnaces, the indicators of low-iron mullite and low-creep lightweight bricks are extremely good. The change rate of the refiring line is 1600℃×2h, -0.2%, and the high temperature resistance is good. Especially at 1600 ℃, the volume does not expand, which is the main consideration to solve the problem. The corresponding low-iron mullite low-creep lightweight brick has a very good thermal insulation rate, which is ultra-low thermal conductivity, low refiring Lightweight brick with linear change rate, the refired line change rate is 1400℃×2h, -0.66%, and has good high temperature resistance. The characteristics of these two materials, especially at 1400℃-1600℃, that the volume does not expand is the solution to the problem The main considerations, directly become the core material of the hot blast piping system of the low-carbon super-large blast furnace.

Through repeated analysis of physical and chemical indicators and repeated thermal calculations, the hot air duct of the present invention is proposed, which adopts low thermal conductivity, low iron mullite, high temperature, non-expansion, double-layer ultra-thick heat insulation ring technology. Among them, the low-iron mullite low-graining line change rate lightweight brick is used, and the high-temperature performance is close to the low-creep andalusite brick of the pipeline working layer. The working condition is to meet the high temperature of 988°C in the working area. Good low thermal conductivity of lightweight bricks. According to the refractory material configuration and temperature field analysis of the blast furnace hot blast furnace hot blast pipeline, the temperature of the working hot surface near the inner side of the pipeline is reduced from 489°C to 188°C, which greatly reduces the shell temperature of the hot blast pipeline system and achieves the goal of energy saving.

The hot air pipeline of the present invention comprises a steel shell, a spraying pipe and a heat insulating layer, the spraying pipe is close to the inner side of the steel shell, and the heat insulating layer is on the inner side of the spraying pipe, and is characterized in that: the heat insulating layer has an outer heat insulating layer, a middle Heat insulation layer, inner high-temperature working layer and fiber blanket; the outer heat insulation layer of staggered seams is built on the inner side of the spraying pipe, and the outer heat insulation layer is low-iron lightweight brick; the middle heat insulation layer of staggered seams is built Built on the inner side of the outer heat insulation layer, the middle heat insulation layer is low-iron mullite lightweight brick; the inner high-temperature working layer of staggered joints is built on the inner side of the middle heat insulation layer, and the inner high-temperature working layer is low-creep andalusite brick;

The fiber blanket is a high-alumina fiber with a high temperature resistance of 1200°C, which is in the direction of 110˚-130˚ on the upper part of the outer heat insulation layer;

The circumference of the outer heat insulation layer, the middle heat insulation layer and the inner high-temperature working layer are staggered seams;

In the longitudinal section, the outer heat insulation layer, the middle heat insulation layer and the inner high temperature working layer are phased and staggered;

The outer heat insulation layer, the middle heat insulation layer and the whole circle of the high-temperature working layer are separated longitudinally by 3000±500mm in the longitudinal direction of each brick, and there are respectively 8±2mm first expansion joints, second expansion joints and third expansion joints, The first expansion joint, the second expansion joint and the third expansion joint are stuffed with high-temperature high-alumina fibers; the outside of the second expansion joint of the middle heat insulation layer and the third expansion joint of the inner high-temperature working layer are made of corresponding outer layer bricks Press down; the distance between the first expansion joint of the outer heat insulation layer and the second expansion joint of the middle heat insulation layer is greater than 250 mm, and the distance between the third expansion joint of the inner high temperature working layer and the second expansion joint of the middle heat insulation layer The spacing between them is greater than 250 mm.

In detail, the refiring line change rate of the low-iron lightweight bricks constituting the outer heat insulation layer is 1400°C×2h, -0.66%, volume density/(g/cm ³ ) 0.64, thermal conductivity (350°C) [W/(m·K)] 0.20;

The refiring line change rate of the low-iron mullite lightweight brick constituting the middle insulation layer (3) is 1600×2h-0.2%, the bulk density/(g/cm3) is 0.98, and the thermal conductivity (350°C) [W/(m·K)] 0.308;

The refiring line change rate of the low-creep andalusite brick (10) constituting the inner high-temperature working layer (4) is 1500°C×2h, 0-+0.2%, and the creep rate is 1500°C×3h<0.2% heat conduction Coefficient (350°C) 2.07, thermal shock stability > 3 hours at 1100°C.

The thickness of the high temperature fiber is 15±2mm.

The outer heat insulation layer and the middle heat insulation layer are all built with low-iron mullite lightweight mud, and the inner high-temperature working layer is built with low-creep andalusite mud; the outer heat insulation layer, the middle heat insulation layer and the inner high temperature The working layers are filled with low-iron mullite light mud.

In order to improve the firmness of the hot air pipeline, the top of the inner high-temperature working layer is a special-shaped pipe closing brick, and there is a middle special-shaped brick in the middle. The two first special-shaped bricks with one side bent and the other side protruding in the middle are closely attached, and the second special-shaped bricks with 6-10 pieces on each side are the second special-shaped bricks with one side concave in the middle and the other side protruding in the middle, the outermost What the outside of the second special-shaped brick is close to is the third special-shaped brick that one side is concave in the middle and the other side is flat.

In the above-mentioned hot air duct, the longitudinal direction of each brick in the outer heat insulation layer, the middle heat insulation layer and the circumference of the high-temperature working layer is 3000±260mm apart, and there are respectively 8±2mm first expansion joints, The second expansion joint and the third expansion joint. Easy to operate.

Beneficial effects of the present invention

Adopting the hot blast pipeline of the present invention has obvious energy-saving effect compared with the existing hot blast pipeline, stable structure, low shell temperature, can slow down intergranular corrosion, and prolong the service life of the pipeline; the surface temperature of the outer steel shell of the hot blast pipeline is compared with the existing The hot air duct drops from 166°C to 97°C, with a temperature difference of about 69°C. Production practice has proved that the low thermal conductivity, low iron mullite high temperature non-expansion double-layer ultra-thick heat insulation ring technology is first applied in the hot air pipeline system, which not only reduces the temperature of the pipeline shell, but also greatly reduces the radiant heat around the pipeline. When people are near the pipeline, the heat they feel is much higher than the calculated value of the ambient temperature rise caused by convection. Therefore, it has a good environmental effect. At the same time, the noise is reduced by 5 decibels.

Due to the application of low thermal conductivity, low iron mullite, high temperature, non-expansion, double-layer ultra-thick heat insulation ring technology, the loss of air temperature is small, and the air supply time of the hot blast stove is extended by 3-5 minutes, and the life of the hot blast stove is relatively extended by 5%. , extended from the design furnace life of 25 years to 26.25 years. There has been no maintenance for many years of trial operation, which reduces maintenance costs, and the temperature is around 97°C. The blast furnace hot blast pipe runs well, and no maintenance is required within the design age of the hot blast stove. Since the maintenance cost is almost zero, the estimated economic benefit of saving 600,000 maintenance fees per year is very good. At the same time, because there is no failure, it lays a solid foundation for the smooth operation of the blast furnace.

Because the temperature difference before and after use is about 69°C. According to the calculation of thermodynamics and the comparison of empirical values, the coke ratio for blast furnace ironmaking is reduced by 3-4 kg/ton of iron, which saves 9897.867 tons of coke per year compared with blast furnaces, and the annual energy saved is worth 16.826373 million yuan. At the same time, 36,292 tons of carbon emissions were reduced.

Description of drawings

Figure 1 is a transverse sectional view of the hot air duct.

Fig. 2 is a partially expanded top view of the inner working layer.

Fig. 3 is a partial sectional view along line A-A in Fig. 1 .

In the above figure:

1. Spraying pipe, 2. Outer insulation layer, 3. Middle insulation layer, 3.1. Low iron mullite lightweight brick, 4. Inner high temperature working layer, 5. Fiber blanket, 6. Middle special-shaped brick, 7. The first special-shaped brick, 8. The second special-shaped brick, 9. The third special-shaped brick, 10.

Low creep andalusite brick, 11. Low iron lightweight brick, 12. Steel shell, 13.1. First expansion joint, 13.2. Second expansion joint, 13.3. Third expansion joint, 14. Expansion joint covering brick.

Detailed ways

The specific implementation of the present invention will be described in detail below in conjunction with the examples and accompanying drawings, but the specific implementation of the present invention is not limited to the following examples.

Example

The hot air duct is a common component in the steel industry. For the convenience of description, a 9m long hot air duct is used as an example to illustrate. The structure of the hot air duct of this embodiment is shown in FIG. 1 . The hot air duct has a steel shell 12 with a length of 9 m, and the spraying pipe 1 (model CN-130G) inside the steel shell 12 has a diameter of Φ3120 mm and a thickness of 60 mm. In the spraying pipe 1, there is an outer heat insulation layer 2 with staggered joints, the thickness of the outer heat insulation layer 2 is 150mm, and the masonry mud in the outer heat insulation layer 2 is low-iron mullite light mud. In the outer heat insulation layer 2, there is a middle heat insulation layer 3 built by staggered joints, and the thickness of the middle heat insulation layer 3 is 150mm (300mm refers to the thickness of 2 layers of heat insulation bricks). The inner high-temperature working layer 4 is arranged in the middle insulation layer 3 by means of staggered seam and biting masonry, as shown in Fig. 2, and the thickness of the inner high-temperature working layer 4 is 200mm. The inner diameter of the inner high temperature working layer 4 is Φ1960mm.

There is a fiber blanket 5 (a high-alumina fiber with a high temperature resistance of 1200°C) in the direction of 120°-122° on the upper part of the outer heat insulation layer 2, and the thickness of the fiber blanket 5 reaches 15 mm. Meet radial expansion requirements.

Between the outer heat insulation layer 2 and the middle heat insulation layer 3, and between the middle heat insulation layer 3 and the inner high temperature working layer 4 are also staggered joints, see Fig. 3 .

On the inner side of the sprayed layer 1, there is a 9m-long outer heat insulation layer 2 built with low-iron mullite light mud staggered joints, at a distance of 3000±20mm from one end of the steel shell 12 (this distance is one brick short, it The length of both sides, so half is 3000 ± 20mm, and the other half is longer than 3000 ± 20mm half section brick such as half 125mm of the brick length of 250mm, is 3125 ± 20mm. In the present embodiment, 3000 ± 20mm place, also refers to simultaneously 3125±20mm, 6000±20mm, also refers to 6125±20mm; the expansion joints at 3125±20mm and 6125±20mm are the same as those at 3000±20mm and 6000±20mm, and will not be described separately. In this embodiment, other similar distances, and so on), and at a distance of 6000±20mm from one end of the steel shell 12, leave an 8mm axial first expansion joint 13.1, and fill and compact the first expansion joint 13.1 High-temperature high-alumina fiber; the thickness of the outer heat insulation layer 2 is 150mm, and the outer heat insulation layer 2 is made of low-iron lightweight bricks. cm ³ ) 0.64, thermal conductivity (350°C) [W/(m K)] 0.20;

On the inner side of the outer heat insulation layer 2, there is a 9m-long intermediate heat insulation layer 3 built with low-iron mullite light mud staggered joints, at a distance of 3260±20mm and 6260±20mm from one end of the steel shell 12 (the second expansion joint 13.2 The distance from the first expansion joint 13.1 is greater than 250mm), leave an 8mm axial second expansion joint 13.2, and fill the second expansion joint 13.2 with compacted high-temperature high-alumina fibers, see the black thick line in Figure 3 ; The thickness of the middle insulation layer 3 is 150mm, the middle insulation layer 3 is made of low-iron mullite lightweight bricks, the change rate of the refiring line is 1600×2h -0.2%, and the volume density/(g/cm3) is 0.98 , thermal conductivity (350°C) [W/(m K)] 0.308;

On the inner side of the middle insulation layer 3, there is a 9m-long inner high-temperature working layer 4 built with low-creep andalusite brick mud staggered joints. ±20mm and 6260±20mm), leave 8mm axial third expansion joint 13.3 (the distance between the second expansion joint 13.2 and the third expansion joint 13.3 is greater than 250mm), fill the third expansion joint 13.3 Compact the high-temperature high-alumina fiber, see the thick black line in Figure 2; the thickness of the high-temperature working layer 4 is 200mm, the inner diameter of the high-temperature working layer 4 is Φ1960mm, the material is low-creep red column brick, and the change rate of the reburning line is 1500℃×2h, 0-+0.2%, creep rate 1500℃×3h<0.2%, thermal conductivity (350℃) 2.07, thermal shock stability 1100℃>3 hours; there is a brick in the outer insulation layer 2 (from The location is called the expansion joint cover brick 14. The mesh line in the figure indicates that it is the brick that presses the second expansion joint 13.2) Pressing the second expansion joint 13.2 of the middle insulation layer 3 from the outside, the middle insulation layer 3 has a low creep The red column capping brick presses the third expansion joint 13.3 of the inner high temperature working layer 4 from the outside, see Fig. 3, the first expansion joint 13.1 among the figure also can be arranged on the right side of the second expansion joint 13.2.

And make the outer heat insulation layer 2, the middle heat insulation layer 3 and the inner high temperature working layer 4 be staggered joint masonry, in the axial section, it is a staggered joint masonry form, see Figure 3. The brick joints of the outer heat insulation layer 2, the middle heat insulation layer 3 and the inner high temperature working layer 4 are not on the same diameter line. And it is not on the same cross-section of the pipeline, which meets the requirements of axial absorption expansion; avoids the safety hazard of hot air stringing out.

In this embodiment, the outer heat insulation layer 2 is low-iron lightweight brick 11 with ultra-low thermal conductivity, the model is D14-1, and the main technical parameters are re-firing line change rate 1400°C×2h, -0.66%, volume density/ (g/cm ³ ) 0.64, thermal conductivity (350°C) [W/(m·K)] 0.20. The outer ring low-iron lightweight brick 11 is fully built; the middle insulation layer 3 is low-iron mullite lightweight brick 3.1, model D16-1, the main technical parameters change rate of refiring line is 1600*2h-0.2%, volume Density/(g/cm3) 0.98, thermal conductivity (350°C) [W/(m K)] 0.308; inner high temperature working layer 4 is mainly low creep andalusite brick 10, model is CP150 (including CP150-1, 2, 3 This is the number adopted due to the change of the external size of the brick, and the material is uniform) Main technical parameters Refractoriness > 1790 degrees, change rate of refiring line 1500℃×2h, 0-+0.2%, creep Rate 1500℃×3h<0.2% Thermal conductivity (350℃) 2.07, thermal shock stability 1100℃>3 hours.

In the inner high-temperature working layer 4, there is a middle special-shaped pipe closing brick 6 in the middle of the top of the inner working layer low-creep andalusite brick. 6 The model of the two first special-shaped bricks 7 attached to both sides is CP150-4; the second special-shaped brick 8 is close to the first special-shaped brick 7, and the eight second special-shaped bricks 8 on each side are stacked together (with andalusite mud in between), the model of the second special-shaped brick 8 is CP150-3, the outside of the eighth second special-shaped brick 8 is the third special-shaped brick 9, and the model of the third special-shaped brick 9 is CP150-2.

Claims (4)

1. a kind of hot air duct, it includes box hat（12）, spray pipe（1）With thermal insulation layer, spray pipe（1）It is close to box hat（12）It is interior Side, thermal insulation layer is in spray pipe（1）Inner side, it is characterized in that：

Described thermal insulation layer has outer thermal insulation layer（2）, intermediate thermal insulating layer（3）With interior hot operation layer（4）And tapetum fibrosum (5)；The fissure of displacement Sting the outer thermal insulation layer of block（2）Build by laying bricks or stones in spray pipe（1）Inner side, outer thermal insulation layer（2）It is low iron light-weight brick；The fissure of displacement stings the centre of block Thermal insulation layer（3）Build by laying bricks or stones in outer thermal insulation layer（2）Inner side, intermediate thermal insulating layer（3）It is low iron light mullite brick；The fissure of displacement stings the interior height of block Warm working lining（4）Build by laying bricks or stones in intermediate thermal insulating layer（3）Inner side, interior hot operation layer（4）It is low creep andalusite brick；

Tapetum fibrosum (5) is the high aluminum fiber of 1200 DEG C of high temperature resistant, is in outer thermal insulation layer（2）The direction of top 110-130；

Outer thermal insulation layer（2）, intermediate thermal insulating layer（3）With interior hot operation layer（4）Circumference be that the fissure of displacement stings block；

In longitudinal profile, outer thermal insulation layer（2）, intermediate thermal insulating layer（3）With interior hot operation layer（4）Between be mutually with staggeredly；

Outer thermal insulation layer（2）, intermediate thermal insulating layer（3）With hot operation layer（4）The circumference domain each brick longitudinal direction, be separated by 3000 ± 500mm, there is 8 ± 2mm the first dilatation joint respectively（13.1）, the second dilatation joint（13.2）With the 3rd dilatation joint（13.3）, the One dilatation joint（13.1）, the second dilatation joint（13.2）With the 3rd dilatation joint（13.3）In fill up high temperature high aluminum fiber；Middle spaced heat Layer（3）The second dilatation joint（13.2）With interior hot operation layer（4）The 3rd dilatation joint（13.3）Outside by corresponding outer Layer brick is pushed down；Outer thermal insulation layer（2）The first dilatation joint（13.1）With intermediate thermal insulating layer（3）The second dilatation joint（13.2）Between Spacing is more than 250 millimeters, interior hot operation layer（4）The 3rd dilatation joint（13.3）With intermediate thermal insulating layer（3）The second dilatation joint （13.2）Between spacing be more than 250 millimeters.

2. a kind of hot air duct according to claim 1, it is characterized in that：The outer thermal insulation layer of described composition（2）Low iron it is light The reheating linear change rate on reheating of matter brick is 1400 DEG C × 2h, -0.66%, bulk density/（g/cm³）0.64, thermal conductivity factor（350℃） ［ W/ (mK) ］ 0.20；

Described composition intermediate thermal insulating layer（3）The reheating linear change rate on reheating of low iron light mullite brick be 1600 × 2h-0.2%, Bulk density/（g/cm3）0.98, thermal conductivity factor（350℃）［ W/ (mK) ］ 0.308；

Hot operation layer in described composition（4）Low creep andalusite brick（10）Reheating linear change rate on reheating be 1500 DEG C × 2h, 0-+0.2%, 1500 DEG C × 3h of creep rate<0.2% thermal conductivity factor（350℃）2.07,1100 degree of thermal shock resistance>3 hours；

The high temperature fiber（5）Thickness be 15 ± 2 millimeters；

The outer thermal insulation layer（2）, intermediate thermal insulating layer（3）Built by laying bricks or stones by low iron mullite light mud, interior hot operation layer（4）Adopt Built by laying bricks or stones with low creep andalusite mud；Outer thermal insulation layer（2）, intermediate thermal insulating layer（3）With interior hot operation layer（4）Between by low iron not Carry out the filling of stone light mud.

3. according to a kind of any described hot air duct of claim 1 or 2, it is characterized in that：Described interior hot operation layer（4）'s Top is that special-shaped pipeline closes tweel block, and there is special shaped brick among block centre one（6）, middle special shaped brick（6）The middle part of side wide at the top and narrow at the bottom Bending；Middle special shaped brick（6）Be close to two pieces of both sides while in the middle part of bending another side protrusion the first special shaped brick（7）, it is close to One special shaped brick（7）Be protrusion in the middle part of recessed another side in the middle part of one side of every 6-10 pieces of side the second special shaped brick（8）, the of outermost Two special shaped bricks（8）What outside was close to is the 3rd special shaped brick that the recessed another side in middle part is flat on one side（9）.

4. according to a kind of any described hot air duct of claim 1 or 2, it is characterized in that：Described outer thermal insulation layer（2）, it is middle Thermal insulation layer（3）With hot operation layer（4）The circumference domain each brick longitudinal direction, be to be separated by 3000 ± 260mm, have 8 respectively ± 2mm the first dilatation joint（13.1）, the second dilatation joint（13.2）With the 3rd dilatation joint（13.3）.