About compound silicate insulation materials in the steam pipe insulation application

Summary of the power plant main steam pipe outer surface temperature exceeded the phenomenon to analyze technical solutions proposed renovation and construction process requirements, introduce composite silicate insulation materials in the steam pipes in the successful application of energy-saving.

Keywords steam pipe insulation energy saving environmental applications

First, the transformation of the former thermal power plant problems in high-temperature high-pressure units 12MW second main steam pipe, the original design of rigid insulation material is molded porous calcium silicate, in the operation of the units start and stop the pipeline thermal displacement, alternating squeeze pressure pipeline slight vibration, long-term use of high temperature and other reasons, resulting in fragmentation of calcium silicate powder, the formation of many cracks, insulation materials, heat sealing performance, easy steam pipe heat radiated. Meanwhile insulation voids collapse, especially in the horizontal pipe and vertical pipe sections handover elbow out of line, the insulation effect is not ideal, the average temperature of the outer surface 55 ℃, the local temperature up to above 150 ℃, heat losses.

By GB4272 - 92 << equipment and piping insulation technology General >>, the outer surface of the equipment or piping insulation measures taken after the temperature of the outer surface of the insulation layer must be less than 50 ℃ provisions, the outer surface temperature has exceeded a result, energy consumption work as a need to address the most urgent task, and pipe insulation energy-saving needs of both technologies is an important part of enterprise management is also an important way of saving energy, so plant in 2005 for 1 #, 2 # unit were the main steam pipe insulation energy saving.

Second, the choice of insulation materials

(A performance comparison of thermal insulation material forming porous calcium silicate products with hard texture, thermal shock resistance, plasticity poor, easily broken powder, bulk density is higher, many kinds of material specifications, materials management workload and other shortcomings.

Compound silicate fiber and composite silicate cream products with soft, low density, thermal conductivity, excellent thermal stability and thermal shock resistance, excellent tensile strength, non-corrosive pollution, simple construction, plasticity, long life, thermal expansion is small, there will be no outsourcing metal crack, bump, etc., which are particularly good insulation effect.

(Two product overall economic

Compound silicate fiber and composite silicate insulation material in paste under the same conditions, the use of a thickness of rigid molded three-fifths of porous calcium silicate insulation materials, pipe outer protective layer allows a corresponding reduction in the amount of 18% , corresponding to 20% reduction in heat loss, whether it is a one-time investment, or an annual cost of heat loss, etc., are the use of composite silicate compound silicate gypsum fibreboard and insulation materials for the most economical, and has a good overall economic efficiency .

(Three) the choice of insulation material

Through the above comparison, the main steam pipe insulation material made of composite fiber and composite silicate paste silicate insulation materials.

Third, the transformation of the construction technology solutions and process requirements (one removed from the boiler main steam outlet header tank to the high pressure turbine within the scope of the original pipe insulation, pipe surface cleaned of dust and rust.

(B using compound silicate insulation material paste directly on the pipe, valve surface for painting, based on a thickness of 20mm insulation.

(Third in the main steam pipe insulation layer on the basis of a thin wire fiber bundle layer 3 complex silicates, each having a thickness of 25mm, it wrong seam paste, and the paste composite silicate insulation material applied insulation gap, ensure heat sealing performance in the first layer of composite silicate fiberboard 1,2,3 topical whole bundle of fine wire, tighten to prevent the insulation layer sliding dislocation. outer silicate paste using a composite insulation material thickness of 20mm sealed smear , a thickness of 95mm the primary insulation layer.

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(Iv main insulation of the main steam pipe layer, a thin layer of composite silicate fiber bundle wire thickness of 25mm, it wrong seam paste, and the paste composite silicate insulation material applied insulation gap and ensure the insulation sealing performance in the fourth layer composite silicate fiber bundle external overall fine wire mesh, tighten, the insulation layer to prevent sliding dislocation. outer paste composite silicate insulation material used for the sealing coating thickness of 10mm, a thickness of 35mm enhanced insulation.

(V main steam pipe insulation layer insulation layer based (20mm), the primary insulation layer (95mm) and strengthen the insulation layer (35mm, total thickness is 150mm.

(Six outermost protective layer of metallic material packets with 0.8mm aluminum skin adjacent lap of not less than 40mm, and leave in place the free expansion margin. Installation should be close to the insulation layer, circumferential seams longitudinal seams and horizontal joints must take on under a downstream direction. elbow aluminum skin of the outer arc an additional a width of 50mm aluminum skin vertical connection, so that the hoop elbow aluminum skin, portrait can be connected a solid whole, no disjunction.

(Seven after construction of the insulation layer shall cover equipment nameplate, instrumentation, etc. The name of the device, the medium flow identification, color code in a timely manner of the restoration.

Fourth, after the transformation effects and economic analysis

(A before and after reconstruction of the outer surface temperature monitoring points compared to elbow as a monitoring point, its transformation before and after the point of the elbow to monitor the temperature of the outer surface temperature. Implementation of energy-saving insulation, the outer surface temperature in full compliance with GB4272 - 92 required standards, the original over-temperature points have been eliminated, the average temperature dropped 22 ℃, insulation effect has been significantly improved.

(Two heat loss compared before and after reconstruction

Heat loss is usually heat flux q (W/m2 expressed. Heat loss and heat dissipation area of ​​the product, that is, the area of ​​heat dissipation, so heat loss within the cooling area represents the region of the insulation condition, the indicator is to test thermal equipment The main indicators of a thermal effect. transformation of the former heat loss: the main steam temperature of 550 ℃, the average temperature of the outer surface of the front T w = 55 ℃, 25 ℃ ambient temperature according to the same calculation: @ transformed before 10.92W / (m2.k , q transformation of the former is 327.6W/m2.

As can be seen, before the transformation of heat loss has exceeded the standard value.

(2) After the transformation heat loss:

The average temperature of the outer surface after T w = 33 ℃, 25 ℃ ambient temperature according to the same calculation: α transformation of 9.82W / (m2.k, q after transformation 78.56W/m2.

It can be seen that after transformation, reducing heat loss than the standard value.

(Three after the transformation of economic analysis

Comparative analysis of heat transfer unit calculation, where the main steam pipe insulation, the outer surface of the heat transfer area A = 900m2.

Reduce heat loss Δq = q-q before the transformation after transformation = 249.04W/m2, lower rate q% = 76%, reduce the heat flux loss ΔΦ = A Δq = 224136 W.

After transformation within 1h reduce heat dissipation, namely energy Q = ΔΦ × h = 806889.6kJ, with annual operating unit 6000h, boiler thermal efficiency η = 90% calculated, you can run an annual savings of standard coal quantity B b = QbQη × h = 183540kg , coal price at 1,000 yuan / t per year savings: 183.54 × 1000 = 183540 yuan, has achieved remarkable economic benefits.

IV Conclusion

(A through 1 #, 2 # unit main steam pipe insulation energy saving, the average surface temperature from 55 ℃ outside dropped to 33 ℃, its energy efficiency, environmental performance has greatly improved, reducing the unit's cooling heat loss and environmental pollution.

(Two years to run a standard coal saved amount 184t, saving coal capital of about 180,000 yuan, while reducing smoke and sulfur emissions, and achieved good economic and social benefits, composite silicate insulation materials worth Other heat pipe insulation promote the use of energy-saving transformation.

References:

[1] Ministry of Water Resources Electric Power Planning and Design Institute, power plants and heating equipment and piping insulation and painting design requirements, (SDGJ59-841984

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