共查询到19条相似文献,搜索用时 109 毫秒
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结合热负荷延续图的负荷分配,分析了采用两种相同容量但采暖抽汽压力不同的供热机组的能量损失差别,以及在相同的进汽量条件下,要获得相同的供热量,两种汽轮机的发电功率的不同。在满足热网换热器传热端差要求的条件下,供给采暖热用户的抽凝机的抽汽压力或背压机组的排汽压力应尽可能降低,以利提高热电厂能源利用率和经济性。在制造和选择供热汽轮机时除了要考虑热化系数之外,还应注重抽汽或排汽压力与热负荷能级品位的匹配。 相似文献
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§12-1 调节基本原理与自整要求 背压式汽轮机以不同参数的蒸汽向热用户供热,是一种合理的供热方式,带抽汽的背压式汽轮机(简称“抽背机”)能满足这一要求。它分非调整抽汽式及调整抽汽式两种,这种机组在供电的同时可向热用户供应两种参数的热负荷。非调整抽汽式背压机的抽汽量根据用户需要手动调节,它一般为中、低压进汽参数。抽汽量的改变不仅影响汽轮机转速(单机)或电功率(并网),同时也直接影响到背压。高参数的抽背机,当抽汽量频繁变化时,机组 相似文献
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供热系列汽轮机包括单抽汽式(C)、双抽汽式(CC)、抽汽背压式(CB)和背压式(B)汽轮机。供热汽轮机的通流部分按调整抽汽压力分成在不同压力区间工作的几部分,每部分都由各自的调节级和压力级组所组成,各部分前的压力通过调节阀或迥转隔板来整定。因此抽汽式汽轮机的各通流部分都可被看作是一单独的汽轮机,可对其分别进行通流设计,然后根据需要组成不同类型的抽汽式汽轮机,从而形成完整的供热汽轮机系列。根据部颁标准,供热系列汽轮机的功率、转速、新汽参数和调整抽汽压力 相似文献
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自动底盖设备就其技术类型而言主要分为两种:一种在采用法兰密封技术的基础上增加液压元件,使之完成自动开关盖动作,以及施加、解除密封力,此技术进油方式仍为底部中心进料,以美国哈恩.克莱(Hahn&Clay)、福斯特惠勒(Foster Wheeler)公司产品为代表。另一种是2000年以后推出的采用阀门密封技术的自动底盖设备,此技术采用大口径平板闸阀完成塔底口自动开闭,进油采用侧进料方式,以Delta Valve公司、Z&J公司产品为代表。惠州炼油延迟焦化装置采用周期性除焦生产方式,生焦周期一般为18~24h,期间有换塔、小吹汽、大吹汽、小给水、大给水、放水、除焦、除焦塔试压、预热、切四通生焦等工序。该装置焦炭塔底卸盖系统采用4套德国Z&J公司双闸板闸阀式自动底盖机。结合装置应用实际,介绍此类底盖机的结构原理、控制系统与工作模式。运行实践表明,Z&J自动底盖机具有密封效果好,蒸汽耗量低,开关时间短,运行平稳的优点。 相似文献
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Kwon-Yeong Lee Moo Hwan Kim 《International Journal of Heat and Mass Transfer》2008,51(21-22):5333-5343
Experimental and analytical studies were performed to examine local condensation heat transfer coefficients in the presence of a noncondensable gas inside a vertical tube. The experimental data for pure steam and steam/nitrogen mixture bypass modes were compared to study the effects of noncondensable nitrogen gas on annular film condensation phenomena. The condenser tube had a relatively small inner diameter of 13 mm. The experimental results demonstrated that the local heat transfer coefficients increased as the inlet steam flow rate increased and the inlet nitrogen mass fraction decreased. The results obtained using steam/nitrogen mixtures with a low inlet nitrogen mass fraction were similar to those obtained using pure steam. Therefore, the effects of noncondensable gas on steam condensation were weak in the small-diameter condenser tube because of interfacial shear stress. A new correlation based on dimensionless shear stress and noncondensable gas mass fraction variables was developed to evaluate the condensation heat transfer coefficient inside a vertical tube with noncondensable gas, irrespective of the condenser tube diameter. A theoretical model using a heat and mass transfer analogy and simple models using four empirical correlations were developed and compared with the experimental data obtained under various experimental conditions. The predictions of the theoretical model and the simple model based on a new correlation were in good agreement with the experimental results. 相似文献
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为了提高能源利用效率,提高经济效益和环境效益,燃气一蒸汽联合循环热电联产系统已受到广泛的关注,目前国内大部分的联合循环机组均要求热电联供,为工业用汽或城市采暖提供蒸汽。本文介绍了东方汽轮机/三菱重工M701F4燃气轮机“二拖一”联合循环热电联供系统及其特点,分析了供热设计条件下该系统的热电负荷特性,供工程设计和电厂运行参考。 相似文献
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Characteristic curves and the promotion effect of ethanol addition on steam condensation heat transfer 总被引:1,自引:0,他引:1
Although most previous studies concerning the condensation of binary vapor mixtures report the condensation rates to be less than that for pure vapor, heat transfer enhancement can be realized by using additives to form a positive system (solutal Marangoni condensation). The objective of the present study was to clarify the effect of mixing ethanol into steam on condensation heat transfer. Precise measurements of the ethanol concentration in the vapor of water-ethanol mixtures were performed over a wide range of ethanol concentrations, and the condensation behavior was observed. The maximum heat transfer coefficients in the condensation characteristic curves were determined to be 0.12 and 0.18 MW/m2 K for vapor velocities of 0.4 and 1.5 m/s, respectively, and appeared at an ethanol vapor mass fraction of approximately 1%. The mixing was demonstrated to be extremely effective, particularly in the low-ethanol concentration range. The condensation heat transfer was enhanced approximately 2-8 times compared to pure steam. 相似文献
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在具有温度梯度的凝结表面上进行了水-酒精混合蒸气的Marangoni凝结的实验。研究了3种流速(V=2、4和6 m/s)对凝结表面上不同位置热流密度的影响。研究发现:流速对纯水蒸气和混合蒸气凝结时的表面温差和热流密度的影响是不同的。对纯水蒸气而言,流速增大后,表面温差和热流密度是增加的,并加剧了热流密度的分布不均(热流密度的相对差值在压力为31.2 kPa,流速2 m/s时为0.538,流速4 m/s时为0.6,流速6 m/s时为0.625)。对于混合蒸气,表面温差随流速的增加而减小,而热流密度增大很少(压力31.2 kPa,流速2 m/s时为0.186,4 m/s时为0.182,6m/s时为0.098)。 相似文献
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为了研究不可凝气体(non-condensable gases, NCG)对火电与光热发电机组上广泛使用的大扁管空冷凝汽器性能的影响,以工程机组凝汽器上普遍应用的通流面积220 mm×20 mm的大扁管为研究对象,针对汽轮机典型工况下的实际蒸汽流量,基于Lee相变方程、VOF方法以及组分扩散模型,对蒸汽与NCG混合气体管内两相流凝结换热进行数学建模与数值计算。结果表明:由于大扁管的狭窄通流几何结构与高蒸汽流量,NCG对管内蒸汽凝结的抑制效果要远低于预期;当入口空气质量分数按2%增加时,凝结管凝结换热系数仅下降2%左右,这与NCG导致低流量圆管凝结性能急剧下降的结论不同;空气正常泄漏不会导致空冷凝汽器性能下降而影响发电机组效率。 相似文献
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