【摘要】：中國的燃煤電廠在提供電能的同時消耗了大量的煤炭資源,電站鍋爐作為電廠的主要設備之一,其效率會影響電廠整體的經(jīng)濟性,降低鍋爐熱損失能有效地提高鍋爐效率,而排煙熱損失占鍋爐熱損失的比重最大,因此通過余熱回收系統(tǒng)來回收煙氣余熱是重要的節(jié)能措施。以國內(nèi)某680MW超臨界機組為例,針對低溫省煤器與回熱系統(tǒng)不同的集成方式,建立了串聯(lián)、單級并聯(lián)、跨級并聯(lián)以及串并聯(lián)混合6種集成方案,并得到了最優(yōu)的集成方案;基于FLUENT軟件研究了氟塑料光管低溫省煤器的流動換熱特性,并分析了管束排列方式、管間節(jié)距以及管排數(shù)對流動換熱特性的影響,得到了不同情況下的傳熱和阻力特性,并將模擬值與準則式中的經(jīng)驗計算值進行比較,驗證了模擬的正確性;根據(jù)最優(yōu)的集成方案,在數(shù)值模擬的基礎上,對低溫省煤器從結(jié)構(gòu)型式、管內(nèi)外介質(zhì)的流速、總傳熱系數(shù)以及壓降損失等方面進行了設計,并且進行了經(jīng)濟性分析。結(jié)果表明,當?shù)蜏厥∶浩骺缂壊⒙?lián)于6號低壓加熱器和7號低壓加熱器之間,在進出口水溫分別為53.37℃和120.50℃,進出口煙溫分別為143℃和85℃時,煤耗率降低值最大,節(jié)能效果最好。增設低溫省煤器后,汽輪機抽汽量減少,供電煤耗降低,綜合煤耗率降低了3.942g/(kW·h),回收了煙氣余熱量57.09MW,熱耗率降低了102.27kJ/(kW·h),機組熱經(jīng)濟性相對提高了1.36%,機組年節(jié)約煤量9650噸,年節(jié)煤收益為482.5萬元。
[Abstract]:Coal-fired power plants in China consume a large amount of coal resources while providing electricity. As one of the main equipment in power plants, the efficiency of coal-fired power plants will affect the overall economy of power plants, and reduce the boiler heat loss can effectively improve the efficiency of the boiler. The heat loss of exhaust gas accounts for the largest proportion of boiler heat loss, so it is an important energy saving measure to recover flue gas waste heat through waste heat recovery system. Taking a 680MW supercritical unit as an example, six kinds of integration schemes of series, single stage parallel, cross stage parallel and series-parallel connection are established for different integration modes of low temperature economizer and regenerative system, and the optimal integration scheme is obtained. Based on FLUENT software, the flow heat transfer characteristics of low temperature economizer for fluoroplastic smooth tube are studied, and the effects of tube bundle arrangement, pipe pitch and tube arrangement on flow heat transfer characteristics are analyzed, and the heat transfer and resistance characteristics under different conditions are obtained. The correctness of the simulation is verified by comparing the simulated value with the empirical calculation value in the criterion formula, and according to the optimal integration scheme, on the basis of numerical simulation, the structure type, the velocity of medium inside and outside the tube of the cryogenic economizer, the flow rate of the medium inside and outside the tube are analyzed. The total heat transfer coefficient and pressure drop loss are designed, and the economic analysis is carried out. The results show that when the cross stage of the cryogenic economizer is parallel between the No. 6 low-pressure heater and the No. 7 low-pressure heater, when the inlet and outlet water temperatures are 53.37 鈩，

本文編號：2237398