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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 extrusion ; 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.
改造前保暖存在的问题电厂12MW 次高温次高压机组主蒸汽管道，原预设保暖材料是硬质成型微孔硅酸钙，在运行中因为机组启、停时管道萌生热位移，交变挤压；管道的微小震荡；长时期高温运用等端由，导致硅酸钙碎裂粉化，形成众多裂隙，保暖材料的热严密封闭性能减退，蒸汽管道热量容易向外发出。
By GB4272 - 92 " equipment and pipe 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 been exceeded. Therefore, the energy saving work became urgent need to solve , while 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 a main steam pipe insulation energy saving.
按GB4272 － 92《设施及管道保暖技术通则》，在设施或管道外外表采找保人温处理办法后，其保暖层外外表温度务必小于50℃的规定，外外表温度已经超过标准。因为这个，节能降耗办公变成需求解决的燃眉之急，同时管道的保暖节能改造既然技术的需求，是公司管理的关紧内部实质意义，也是节能降耗的关紧路径，因为这个电厂于2005 年对1#、2# 机组主蒸汽管道施行了保暖节能改造。
Insulation material selection
保温材料的选择
Insulation performance comparison 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 .
Overall economic efficiency products
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 .
Insulation material selection
Through the above comparison , the main steam pipe insulation material made of composite fiber and composite silicate paste silicate insulation materials .
Transformation of the construction technology solutions and process requirements ( a ) Remove the boiler main steam outlet from the tank to the high pressure turbine set within the range of the original pipe insulation , pipe surface cleaned of dust and rust .
Using compound silicate insulation material paste directly in the piping, valves, coated surface , based on a thickness of 20mm insulation .
The basis of the main steam pipe insulation layer 3 with a fine wire bundle fiber composite silicate layer , the thickness of each 25mm, it wrong seam paste and paste composite silicate insulation material applied insulation gap , ensure the thermal insulation sealing performance. In the first topical 1,2,3 layer composite silicate fiberboard whole bundle of fine wire , tighten to prevent the insulation layer sliding dislocation. External insulation material using a composite silicate paste for sealing coating thickness of 20mm , a thickness of 95mm of the main insulating layer.
In the main steam pipe main insulation layer , and with the fine wire bundle fiber composite silicate layer , a thickness of 25mm, it wrong seam paste , and the paste composite silicate insulation material applied insulation gap and ensure the sealing of insulation performance. In the first four layers of fine wire mesh composite silicate fiberboard topical whole bundle , tighten , to prevent the insulation layer sliding dislocation. External insulation material using a composite silicate paste for sealing coating thickness of 10mm , a thickness of 35mm the reinforcing insulation layer .
Main steam pipe insulation layer insulation layer based (20mm), the primary insulation layer (95mm) and strengthen the insulation layer (35mm), a total thickness of 150mm.
Outermost protective layer of material with metal 0.8mm aluminum skin packets , adjacent lap of not less than 40mm, and leave in place free expansion margin. Installation should be close to the insulation layer , circumferential joints , longitudinal seams and horizontal joints must take on under a downstream direction . Elbow aluminum skin of an additional outer arc of a width of 50mm aluminum skin vertical connection , so that the hoop elbow aluminum skin , can be connected into a vertical solid overall , no disjunction .
After construction of the insulation layer shall cover equipment nameplate , instrumentation. Name of the device , the medium flows logo, color in a timely manner of the restoration .
After transformation, the effectiveness and economic analysis
Before and after the transformation temperature monitoring points compared to the outer surface of the elbow as a monitoring point , its transformation before and after the point of the elbow to monitor the temperature of the outer surface temperature . After the implementation of energy-saving insulation , the outer surface temperature in full compliance with GB4272 - 92 standards required of the original over-temperature points have been eliminated , the average temperature dropped 22 ℃, insulation effect has been significantly improved.
Heat loss compared before and after reconstruction
Heat loss is usually heat flux q (W/m2) indicates . Heat loss and heat dissipation area of the product , that is, the area of heat dissipation , so heat loss inside the cooling area represents the region of the insulation condition, the indicator device for testing thermal insulation effect of the main indicators 1 . Before transformation heat loss : 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 : α transformation of the former is 10.92W / (m2.k); q before the transformation is 327.6W/m2.
As can be seen , before the transformation of heat loss has exceeded the standard value.
After transformation, the 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 .
After transformation, the 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.
Conclusion
By 1 #, 2 # unit main steam pipe insulation energy saving , the average outer surface temperature from 55 ℃ down to 33 ℃, its energy efficiency and environmental performance has greatly improved , reducing the unit's heat loss and thermal pollution of the environment .
You can run an annual amount of standard coal saved 184t, saving coal capital of about 180,000 yuan , while reducing smoke and sulfur emissions , and achieved good economic and social benefits , complex silicates other thermal insulation materials worth pipe insulation to promote the use of energy saving transformation .
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