Future Changes in Extreme High Temperature over China at 1.5℃-5℃ Global Warming Based on CMIP6 Simulations

Extreme high temperature(EHT)events are among the most impact-related consequences related to climate change,especially for China,a nation with a large population that is vulnerable to the climate warming.Based on the latest Coupled Model Intercomparison Project Phase 6(CMIP6),this study assesses future EHT changes across China at five specific global warming thresholds(1.5℃-5℃).The results indicate that global mean temperature will increase by 1.5℃/2℃ before 2030/2050 relative to pre-industrial levels(1861-1900)under three future scenarios(SSP1-2.6,SSP2-4.5,and SSP5-8.5),and warming will occur faster under SSP5-8.5 compared to SSP1-2.6 and SSP2-4.5.Under SSP5-8.5,global warming will eventually exceed 5℃ by 2100,while under SSP1-2.6,it will stabilize around 2℃ after 2050.In China,most of the areas where warming exceeds global average levels will be located in Tibet and northern China(Northwest China,North China and Northeast China),covering 50%-70%of the country.Furthermore,about 0.19-0.44 billion people(accounting for 16%-41%of the national population)will experience warming above the global average.Compared to present-day(1995-2014),the warmest day(TXx)will increase most notably in northern China,while the number of warm days(TX90p)and warm spell duration indicator(WSDI)will increase most profoundly in southern China.For example,relative to the present-day,TXx will increase by 1℃-5℃ in northern China,and TX90p(WSDI)will increase by 25-150(10-80)days in southern China at 1.5℃-5℃ global warming.Compared to 2℃-5℃,limiting global warming to 1.5℃ will help avoid about 36%-87%of the EHT increases in China.

Plastic Flow Modeling of Ti-5 Al-2 Sn-2 Zr-4 Mo-4 Cr Alloy at Elevated Temperatures and High Strain Rates

The true stress-sWain relationships of Ti-5A1-2Sn-2Zr-4Mo-4Cr（TC17） alloy with a wide range of strain rates were investigated by tmiaxial quasi-static and dynamic compression tests, respectively. Quasi- static compression tests were carried out with Instron 8874 test machine, while dynamic compression tests were performed with the split Hopkinson pressure bar （SHPB） which was installed with heating device and synchro- assembly system. The dynamic mechanical behaviors tests of TC17 were carded out from room temperature to 800 ℃ at intervals of 200 ℃ and at high sWain rates （5 500-1 9200 s-l）. The stress-strain curves considering temperature-sWain rate coupling actions were obtained. The Johnson-Cook constitutive model was developed through data fitting of the stress-sWain curves. The material constants in the developed constitutive model can be determined using isothermal and adiabatic stress-strain curves at different strain rates. The Johnson-Cook constitutive model provided satisfied prediction of the plastic flow stress for TC17 alloy.

Rheological Properties of Waxy Crude at a Low Temperature in the Presence of Pour Point Depressants

Pour point depressants （PPD） are used to improve the theology of waxy crude. The affect of various factors on the theological properties, and the thermal characteristics of waxy crude treated by PPD have been investigated. The conclusions are as follows： PPD can reduce the pour point and abnormal point of waxy crude, broaden the temperature range of Newtonian fluid of waxy crude, and lower greatly the viscosity of non-Newtonian fluid of waxy crude. The influence of reheating and high-rate shear on the effect of PPD mainly depends on their temperature. When the reheating temperature is more than the abnormal point of crude by 10℃, the reheating process has little effect on the modification effect of PPD. However, when the reheating temperature is below the abnormal point of crude, the reheating process will reduce the modification effect of PPD. When temperature is above the abnormal point of crude, the high-rate shear has little effect on the modification effect of PPD. At a temperature range where a lot of wax is precipitating, high-rate shear will greatly reduce the modification effect of PPD.

高温再热器SA-213TP347H钢管裂纹原因分析

基于一个典型的超临界锅炉再热器出口管道在长期运行过程中出现裂纹的案例,对其采用的SA-213TP347H钢管材料进行宏观检查、成分分析及显微结构检查,揭示了裂纹产生的根本原因。分析结果表明,裂纹的形成与材料在高温、高压环境下经历的力学疲劳及环境诱导腐蚀有关。根据分析结果,提出了材料的合理选用和设备维护建议,以期提高设备可靠性和安全性。

DG2025/25.4-Ⅱ6型锅炉高温再热器区域结焦问题分析及建议

某电厂2号锅炉在高温过热器和高温再热器区域发生严重结焦,致使高温再热器超温,最终导致停炉。通过针对性试验研究,找出了结焦的主要原因,并提出了解决结焦问题的对策。对策实施后,高温过热器和高温再热器区域不再结焦,有效提升了锅炉机组运行的安全性、经济性、稳定性。

B610CF-L2与JFE-HITEN610U2L钢焊接裂纹敏感性对比研究

B610CF-L2与JFE-HI TEN610U2L同属ReL≥490 MPa低温、低焊接冷裂纹敏感性高强钢。在同等条件下,对这两种钢的焊接冷裂纹和再热裂纹敏感性进行试验,结果表明:其冷裂纹敏感性均较低,但具有一定的再热裂纹敏感性,且前者的再热裂纹敏感性比后者稍低。从而为今后低温球罐的建造提供借鉴。

丙烯酸十八酯-丙烯酰十八胺对原油流变性的影响

研究了丙烯酸十八酯 -丙烯酰十八胺共聚物对中原 WC98- 2井原油流变性的影响 ,探讨了降凝剂的筛选、不加剂和加剂原油的全黏温曲线的测定、重复加热和高速剪切对加剂效果的影响和降凝剂的改性效果的时效性 .试验表明 :降凝剂使原油的凝点和反常点降低 ,原油的牛顿流体温度范围变宽 ,并且使非牛顿流体温度下的黏度减小 ,但是 ,牛顿流体温度范围内的黏度基本没有变化 ;重复加热的温度高于原油的反常点 1 0 0℃以上时 ,重复加热对降凝剂的改性效果没有显著影响 .但是 ,重复加热温度低于原油的反常点 ,重复加热显著恶化降凝剂的改性效果 ;在原油的反常点以上 ,高速剪切对降凝剂的改性效果无明显的影响 .在原油析蜡高峰区温度范围内高速剪切 。

高温再热器SA-213TP321H钢悬吊管开裂失效分析

针对某循环流化床锅炉高温再热器SA-213TP321H钢悬吊管弯头开裂问题,采用宏观观察、化学成分测试、金相检验、硬度检测、扫描电镜与能谱等对其开裂原因进行了分析。结果表明悬吊管弯头的硬度偏高,显微组织存在明显的滑移线,且开裂处晶界存在腐蚀。这表明悬吊管未进行有效的固溶处理,碳化物在晶界析出弱化了晶界,在悬吊弯管拉应力以及残余应力、蒸汽应力等共同作用下,导致弯头出现晶间应力腐蚀开裂。

电厂高温再热器SA-213 TP347H钢管开裂原因分析

通过宏观形貌观察、化学成分检测、力学性能检测、显微组织检测、扫描电镜能谱分析等方法,对电厂SA-213 TP347H高温再热器钢管弯头处开裂原因进行分析,确定发生开裂的原因是弯头与直管段过渡区域的局部加热控制不当,导致钢管表层显微组织完全老化所致。该组织缺陷是因钢管在制造、安装过程中的热校造成的。为保证锅炉的安全运行,应尽量避免热校操作,如必须进行热校,应控制热校的温度和时间,避免钢管的组织和性能发生变化。

Dynamic simulation on effect of flame arrangement on thermal process of regenerative reheating furnace

By analyzing the characteristics of combustion and billet heating process, a 3-D transient computer fluid dynamic simulation system based on commercial software CFX4.3 and some self-programmed codes were developed to simulate the thermal process in a continuous heating furnace using high temperature air combustion technology. The effects of different switching modes on injection entrancement of multi burners, combustion and billet heating process in furnace were analyzed numerically, and the computational results were compared with on-site measurement, which verified the practicability of this numerical simulation system. The results indicate that the flow pattern and distribution of temperature in regenerative reheating furnace with partial same-side-switching combustion mode are favorable to satisfy the high quality requirements of reheating, in which the terminal heating temperature of billets is more than 1 460 K and the temperature difference between two nodes is not more than 10 K. But since the surface average temperature of billets apart fi＇om heating zone is only about 1 350 K and continued heating is needed in soaking zone, the design and operation of current state are still needed to be optimized to improve the temperature schedule of billet heating. The distribution of velocity and temperature in regenerative reheating furnace with same-side-switching combustion mode cannot satisfy the even and fast heating process. The terminal heating temperature of billets is lower than that of the former case by 30 K. The distribution of flow and temperature can be improved by using cross-switching combustion mode, whose terminal temperature of billets is about 1 470 K with small temperature difference within 10 K.

Characteristics and accumulation mechanisms of the Dongfang 13-1 high temperature and overpressured gas field in the Yinggehai Basin, the South China Sea

The Dongfang 13-1 is located in the diapiric structure belt of the Yinggehai Basin. The formation pressure of its main gas res- ervoir in the Miocene Huangliu Formation is up to 54.6 MPa （pressure coefficient=l.91） and the temperature is as high as 143°C （geothermal gradient 4.36°C/100 m）, indicating that it is a typical high-temperature and overpressured gas reservoir. The natural gas is interpreted to be coal-type gas derived from the Miocene mature source rocks containing type Ⅱ2-Ⅲ kero- gens as evidenced by high dryness index of up to 0.98 and heavy carbon isotopes, i.e., the δ13C2 ranging from -30.76%o to -37.52%o and δ13C2 ranging from -25.02%o to -25.62%o. The high temperature and overpressured Miocene petroleum system is related mainly to diapir in the Yinggehai Basin and contains more pore water in the overpressured reservoirs due to under- compaction process. The experimental and calculated results show that the solubility of natural gas in formation water is as high as 10.5 m3/m3 under the temperature and pressure conditions of the Sanya Formation, indicating that at least part of the gas may migrate in the form of water-soluble phase. Meanwhile, the abundant gas source in the Basin makes it possible for the rapid saturation of natural gas in formation water and exsolution of soluble gas. Therefore, the main elements controlling formation of the Dongfang 13-1 gas pool include that （1） the diapir activities and accompanying changes in temperature and pressure accelerate the water-soluble gas exsolution and release a lot of free gas; （2） submarine fan fine sandstone in the Huangliu Formation provides good gas-water segregation and accumulation space; and （3） the overlying overpressured mud rocks act as effective caps. The accumulation mechanism reveals that the high temperatural and high pressure structure belt near the diapir structures has a good potential for large and medium-sized gas field exploration.

高温再热器SA-213TP347H钢管裂纹原因分析

通过结构分析、断口检查、硬度测试、抗拉试验、显微组织观察及能谱分析,对电厂高温再热器SA-213TP347H钢管进行裂纹原因分析。结果表明:高温再热器在运行中容易晃动,裂纹处于管夹挤压的凹坑;裂纹处管材的拉伸性能、硬度均符合ASME A213/A213M对SA-213TP347H钢的要求;显微组织为奥氏体和沿晶界分布的含Cr碳化物,裂纹是沿晶裂纹,由管外壁向管内扩展;裂纹处腐蚀产物均含有O、S等非金属元素。分析表明:产生裂纹的原因是由于管夹挤压管道,同时管道结构易晃动,增加了挤压变形处的应力,促进了含Cr碳化物沿晶界析出,形成贫Cr区而导致晶界弱化,并在腐蚀性介质的作用下,导致晶间应力腐蚀开裂。

Preparation of Y_(1-x)Ho_xBa_2Cu_3O_(7-δ) Superconductive Thin Films

Y_(1-x)Ho_xBa_2Cu_3O_(7-δ)(0<x<1) sinsle crystal thin films oriented with the caxis perpendicular to the sur-face were grown by DC magnetron sputtering technique. Target was pieced together with half of YBa_2Cu_3O_(7-δ)(YBCO) and half of HoBa_2Cu_3O_(7-δ)(HBCO) superconducting materials. As the distance between HBCO targetmaterial and substrate is varied , the Ho content in material is changed respectively. When the content of Ho is0. 7 (atom ratio) , the T_c>83K.

热轧轧制温度对高温Hi-B取向硅钢磁性能的影响

通过对比分析不同热轧轧制温度下的板坯高温加热Hi-B硅钢热轧板和常化板的金相组织、第二相夹杂物和表面氧化层,并结合最终产品磁性能,研究了热轧轧制温度对于板坯高温加热Hi-B硅钢磁性能的影响,对相关机理进行了分析。

基于特征优选和机器学习组合模型的锅炉受热面壁温预测

为及时有效预测锅炉壁温的变化趋势,以某火电厂600 MW的1号机组高温再热器为例,提出一种融合特征筛选和极端梯度树(Extreme gradient boosting,XGboost)组合自适应增强算法(Adaptive boosting,Adaboost)模型。首先,利用灰色关联分析法和随机森林特征重要度分析法分别计算锅炉大量的历史运行数据与高再壁温之间的线性和非线性关联度,然后进行综合特征排序。在特征优选的基础上,利用建立的XGboost-Adaboost组合模型进行锅炉高再壁温的预测。结合真实运行数据的实验结果表明,该预测模型的平均相对误差和均方根误差分别为0.18%和1.34℃,预测的精度高于几种相关类型高再壁温的预测方法。

长时高温时效对T23水冷壁焊接接头CGHAZ微观组织的影响

通过高温时效方法分析了焊后未热处理T23水冷壁管焊接接头粗晶热影响区(coarse grained heat affected zone,CGHAZ)在服役过程中形成再热裂纹的微观机理,揭示了工程中未热处理T23水冷壁接头在机组启机后,短期运行容易发生开裂泄漏的内在原因.采用材料表征手段对未时效和高温时效处理后的水冷壁焊接接头CGHAZ硬度、微观组织、析出物物相等进行系统分析.结果表明,在530℃时效100 h后,CGHAZ硬度出现由晶内弥散强化导致的二次硬化现象,随着时效(运行)时间增加,CGHAZ硬度逐渐降低,但时效1000 h后,CGHAZ硬度仍有319 HV高于标准要求;在600℃温度下,随着时效时间的增加,CGHAZ硬度随之降低,组织回复、再结晶、马氏体板条宽化、位错密度降低、C元素及合金元素从基体析出等因素导致的CGHAZ硬度降低作用高于MX碳化物在晶内弥散析出导致的硬度升高,M_(23)C_(6)型碳(氮)化物在晶界、亚晶界逐渐析出和长大.

基于再热器再循环冷却技术的高压供汽方案探讨

在火电机组深度调峰成为常态化运行的前提下,对机组工业供汽的改造提出了更高的挑战。针对660 MW超临界机组高压供汽改造需求,提出以再热器再循环冷却技术为核心的3种供汽方案,并通过变工况热力计算分析方案的可行性及经济性。计算结果表明:30%及以上额定发电负荷在满足单机200 t/h、6.0 MPa、480℃供汽需求时,3种方案均可保证再热器在不超温的工况下安全运行,大幅提高机组宽负荷高压供汽能力;为了避免再热器出口流速超速,还需中调门配合参调运行,通过提高再热蒸汽压力以降低再热蒸汽流速;随着负荷的降低,满足额定供汽流量下的再热器再循环流量就会增加,方案1和方案3全工况下再循环流量相差不大,而方案2的高低负荷下再循环流量的比值可达5倍以上;3种供汽改造方案,方案2最节能,方案3次之,3种方案每年可分别产生3951、4445、4178万元的经济效益,但在实施过程中,对方案的选取要综合考虑投资成本、运行维护量及节能收益等因素。

超高温超高压一次中间再热干熄焦锅炉及发电工艺模拟分析

建立超高温超高压一次中间再热干熄焦锅炉及发电系统工艺流程的模型,应用Aspen HYSYS软件对某工程进行模拟计算,并对计算结果与设计工况对比,验证模型正确性。分析不同影响因素对系统性能的影响,为系统设计和运行提供指导,为提高能源利用率和系统优化提出建议。

某300 MW亚临界锅炉高温再热器泄漏原因分析

高温再热器是亚临界锅炉中的一个重要组件,其主要作用是将排出锅炉的高温高压蒸汽再热至合适的温度,以提高锅炉的热效率。然而,在实际运行中,高温再热器泄漏问题时常出现,给锅炉正常运行和安全运行带来了一定的影响。对某300 MW亚临界锅炉高温再热器泄漏原因进行分析,通过对电厂所送管样的宏观形貌检查、几何尺寸测量、化学成分分析、金相分析、硬度试验和拉伸试验,结果表明,该300 MW亚临界锅炉高温再热器泄漏原因是长期超温导致管子力学性能劣化和微观组织老化、损伤所致的。

锅炉高温再热器长时服役TP310HCbN钢管失效分析

针对某660 MW超超临界机组服役4.6万h后的锅炉高温再热器,通过金相检测、扫描电镜、拉伸试验和冲击试验等方法对泄漏的TP310HCbN钢管的组织形貌和力学性能进行研究。结果表明:长时高温服役使TP310HCbN钢管的金相组织老化至3~4级,晶界析出大量碳化物,管材严重脆化,导致其韧性储备不足,受外力撞击后外壁表面形成大量微裂纹,随着服役时间的延长,管样裂纹逐渐扩展并最终导致爆管泄漏。