发电机氢气纯度湿度不合格及发电机进油分析及防范

发电机进油以及氢气纯度、湿度不合格给大型发电机的安全稳定可靠运行带来潜在的危害.针对大型汽轮发电机运行中存在的氢气纯度和氢气湿度不合格、发电机内进油的原因、危害,重点阐述了如何防范发电机进油、提高氢气纯度、降低氢气湿度的措施.     

660 MW氢冷发电机氢气纯度下降的原因分析及处理

发电机氢气纯度是保证冷却效果和通风效率的一个重要指标。针对湖南某厂#2发电机氢气纯度下降过快的问题,通过对影响氢气纯度下降的各种因素的分析,确定了氢气纯度下降的原因,并在检修中彻底予以解决,氢气纯度下降的速率得到有效控制,使发电机补氢量稳定在优良范围内。     

炼厂氢气资源优化浅谈

随着炼厂氢气耗量的不断增加,需要选用低廉的制氢原料,采用合理的制氢工艺技术,满足炼厂氢气需求.比较变压吸附、膜分离、深冷分离三种氢气提纯分离技术,对加氢等装置尾气中低浓度氢进行回收利用,能够合理利用氢气资源,有效降低生产成本.某炼厂选用焦化干气制氢后,与轻油制氢相比,原料成本下降,氢气纯度提高.根据各用氢装置的用氢压力、用氢量进行匹配,采用从高压到低压的一次通过式流程,只设置一台新氢压缩机,氢气逐级利用.不仅提高了氧气资源利用率,而且有效降低了炼厂综合能耗.采用PRISM膜分离器,从高达10MPa压力的冷高压分离器排放尾气中回收提纯氧气,回收提纯的氢气再回到新氢压缩机的三级人口升压后循环使用.废氧进行胺液脱H2S处理后,采用PSA技术进行废氢回收利用,PSA副产品解吸气升压后作为制氢装置的原料,节约了生产成本.     

降低氢纯度提高PSA氢气回收率的可行性探讨

变压吸附(PSA)作为一种有效的气体分离与净化技术,具有工艺装置操作灵活、自动化程度高等优点,但通过变压吸附的方式回收氢气会存在一定的氢气损失,其损失主要在吸附剂的再生阶段。降低氢纯度提高PSA氢气回收率通过延长吸附时间来实现,延长吸附时间则单位时间内再生次数减少,再生过程损失的氢气减少,氢气回收率提高,但存在杂质穿透吸附剂中分子筛层的风险,对活性炭层影响较小。根据用氢装置对氢气纯度和杂质情况的要求,在不追求氢气高纯度的情况下,通过降低氢纯度提高氢气回收率在一定程度上可以实现,理论上吸附剂损失低于多回收氢气产生的经济效益。通过降低氢气纯度的方式提高氢气回收率的优化思路可分为两类,一是兼顾吸附剂分子筛层寿命,控制进入吸附剂的杂质量,如充分利用氢气跨线、增加原料气预处理或增加原料脱CO2设施等方式;二是牺牲部分分子筛层寿命,不再恢复高纯氢的产出,此方法存在吸附剂失去活性的风险,需要综合权衡。     

加氢型炼厂富氢尾气回收氢气技术

近年来,面对原油质量越来越差、对其相应产品的质量要求越来越高的双重压力,加氢工艺在炼厂中得到越来越广泛的应用,氢气耗量大大增加。氢气的高价格导致炼厂的生产成本大大增加,因而通过回收炼厂富氢尾气中的氢气,能够大大增加炼厂经济效益。以某加氢型炼厂为例,分析了该炼厂多股富氢气体的流量、压力及各组分含量,该炼厂具有较大的回收氢气潜力,对比了变压吸附分离技术、膜分离技术、深冷分离技术和膜分离与吸附分离耦合技术的优劣,结合炼厂实际情况,决定新建膜分离装置并与该炼厂现有PSA装置耦合使用,来提纯该炼厂富氢尾气中氢气。既提高了氢气回收率,又提高了氢气纯度。项目实施后,每年可回收氢气约20kt,增加炼厂效益约2亿元,同时可以为炼厂带来提高燃料气热值,提高加热炉效率等附加收益。     

600MW氢冷发电机氢气纯度下降的原因分析及处理

针对某电厂2号发电机氢气纯度异常下降的问题,对影响氢气纯度的各种因素进行了全面地分析,找出了氢气纯度异常下降的真正原因,彻底地予以解决.     

1000MW机组发电机密封油管道安装位置对氢气泄漏的影响分析

介绍了对某1 000MW电厂发电机氢气泄漏严重问题的检查情况,通过对发电机密封油及氢气系统的研究,发现了由于密封油系统油氢差压阀的两根信号取样管(氢汽压力和密封油压力信号取样管)的安装位置问题而导致取样管内油静压无法合理消除和补偿情况,导致了发电机氢气泄漏量大,并提出了改进措施。     

炼化企业氢气平衡与优化

炼化企业氢气平衡与优化是一个涉及工艺优化、能源管理、环保等方面的综合问题,旨在提高氢气的利用效率,增加效益。为了提高氢气系统管理水平,确保炼化企业临氢装置运行平稳,以某炼油厂为研究对象,对全厂氢源、氢阱现状进行分析,根据氢源压力不同,分2.0MPa和3.0MPa两级向氢阱供应氢气;对正常生产工况和应急工况的氢气平衡控制方式进行总结,提出了氢气系统压力过剩、不足或氢气中断应急处置原则和恢复方案;按氢气纯度对装置的影响,增加了高纯度氢气供硫黄回收装置、某企业2条流程,确保两套装置稳定运行;分析1号加氢装置柴油密度与氢气纯度关系,讨论优化措施;同时根据产氢成本高低,对降低制氢装置负荷、提高连续重整装置负荷、多产廉价氢气进行探讨;根据制氢装置负荷情况,优化氢气压缩机运行模式,6个月增加效益约50.7万元。     

富氢气体中回收氢气技术

加氢裂化装置副产的富氢气体,氢气纯度为85.41％.原设计改入制气装置作为原料补充,但实际生产过程中,由于富氢气体中硫含量在20～500μL/L之间大幅波动,易造成制氢脱硫反应床层穿透,使转化催化剂发生硫中毒;富氢气体中氢气含量较高,易造成制氢加氢催化剂发生反硫化反应,使加氢催化剂失活.因此将这部分气体改入燃料气系统.结合长庆石化公司生产实际,利用现有生产负荷较低的PSA装置和溶剂再生装置,将加氢裂化富氢气体和重整装置的富氢气体混和后,再经脱轻烃、脱硫预处理,预处理后的富氢气体改进PSA装置提纯出99％(体积分数)的氢气,作为加氢裂化装置的补充氢源.氢气资源得到充分利用,既节约了制氢装置天然气用量,又提高了公司管网燃料气热值,还回收了部分液化气组分和硫磺,降低了环境污染,年实现经济效益600万元.     

660 MW发电机漏氢原因分析与处理对策

鸳鸯湖电厂1号发电机为QFSN6602型汽轮发电机,采用水氢氢冷却方式,正常运行时发电机内氢压高于定子冷却水压力;当定子线棒存在裂纹并发生泄露时,将会导致定子冷却水含氢量急剧升高,从而使定子冷却水进入发电机造成发电机烧损.定子冷却水箱安装氢气泄露检测仪,在线检测定子冷却水箱内氢气含量,当氢气浓度达2%时就会报警.讨论了发电机定子冷却水箱内检测仪报警后的原因分析及处理,为同类机组类似故障处理提供参考.     

Hydrogen networks synthesis considering separation performance of purifiers

In hydrogen networks, purifiers are quite often used to reduce operating costs. They should be properly integrated with the whole network in order to maximize the benefit. In this paper, a graphical method is proposed for targeting the minimum fresh resource consumption of hydrogen networks considering separation performance of purifiers. The material balance of the whole hydrogen network shows that the extent of fresh hydrogen reduction is subject to the maximum hydrogen surplus. Based on such observation, the mass transfer triangle is developed to describe the hydrogen transformation from maximum hydrogen surplus to fresh hydrogen. With both the purity and the flow rate of purification streams optimized, the minimum fresh hydrogen consumption can be determined through the proposed graphical method. Two cases are studied to illustrate the proposed methodology.     

Localization of winding shorts using fuzzified neural networks

Shorted turns in field winding of large turbogenerators are difficult to detect and localize. We propose a technique whereby shorts are detected and localized using an artificial neural network with a fuzzified output. The method is based on injecting two simultaneous and identical waveform signals at both ends of the field winding. Selected features of the received signals are used to train the neural network. Once trained, the neural network can detect and localize short turns in the field winding. The proposed method is verified by a field test on 60 MVA turbogenerator. The results show that the proposed method is quite accurate and efficient     

氦质谱技术在大型机组泄漏检测中的应用

应用氦质谱技术解决实际问题的几例典型例子,阐述了氨质谱技术在汽轮发电机组中的胜任及其中的一系列应用技巧。本文认为,利用氦质谱技术测量精度高的优势,结合科学的诊断方法,解决大型机组的诸多泄漏问题,是氦质谱技术应用的新领域。     

A continually online trained neurocontroller for excitation andturbine control of a turbogenerator

The increasing complexity of the modern power grid highlights the need for advanced modeling and control techniques for effective control of turbogenerators. This paper presents the design of a continually online trained (COT) artificial neural network (ANN) based controller for a turbogenerator connected to an infinite bus through a transmission line. Two COT ANNs are used for the implementation; one ANN, the neuroidentifier, to identify the complex nonlinear dynamics of the power system and the other ANN, the neurocontroller, to control the turbogenerator. The neurocontroller replaces the conventional automatic voltage regulator (AVR) and turbine governor. Simulation and practical implementation results are presented to show that COT neurocontrollers can control turbogenerators under steady state as well as transient conditions     

发电机氢气冷却器铜管泄漏检修的新工艺探讨

通过三种氢气冷却器检修方案的比较及经济技术的分析，说明新型检修方案可提高检修效率、检修质量，降低戍本，对企业有较好的经济效益，对氢冷器堵漏具有普遍的应用意义。     

Methylcyclohexane production under fluctuating hydrogen flow rate conditions

Energy storage using liquid organic hydrogen carrier (LOHC) is a long-term method to store renewable energy with high hydrogen energy density. This study investigated a simple and low-cost system to produce methylcyclohexane (MCH) from toluene and hydrogen using fluctuating electric power, and developed its control method. In the current system, hydrogen generated by an alkaline water electrolyzer was directly supplied to hydrogenation reactors, where hydrogen purification equipment such as PSA and TSA is not installed to decrease costs. Hydrogen buffer tanks and compressors are not equipped. In order to enable MCH production using fluctuating electricity, a feed-forward toluene supply control method was developed and introduced to the system. The electrolyzer was operated under triangular waves and power generation patterns of photovoltaic cells and produced hydrogen with fluctuating flow rates up to 7.5 Nm³/h. Consequently, relatively high purity of MCH (more than 90% of MCH mole fraction) was successfully produced. Therefore, the simplified system has enough potential to produce MCH using fluctuating renewable electricity.     

Optimization of VPSA-EHP/C process for high-pressure hydrogen recovery from Coke Oven Gas using CO selective adsorbent

The production of hydrogen through conventional pathways and recovery from by-products typically utilize pressure swing adsorption (PSA) technology as final purification step. Dual-layered PSA columns packed with conventional activated carbon and molecular sieve 5A material exhibit relatively low selectivity for O₂, N₂ and CO in particular. Therefore, eliminating CO (and other poisons) using conventional PSA to acceptable concentrations for EHP/C is only achievable with lower recovery rates. To improve recovery rates, there is a need for a highly efficient purification process that is highly selective for these hydrogen contaminants without compromising the product quality. Here we report an optimization study where vacuum PSA (VPSA) and electrochemical hydrogen purification and compression (EHP/C) technology is utilized for purification and compression of hydrogen from Coke Oven Gas (COG). The VPSA columns were packed with activated carbon and CuCl(7.0)-activated carbon to selectively retain poisonous CO₂ and CO, respectively. The optimal operating conditions were determined with surrogate models produced via non-linear regression of known sample input-output data points, by varying the adsorbent layering ratio (0.30–0.84), adsorption pressure (0.38–0.78 MPa), purge to feed ratio (P/F-ratio) (1–10%), adsorption step time (100–1500 s) and the EHP/C stack current per cell (37–52 A) in the original models. The two-bed VPSA system obtained 90.5% recovery and retained CO and CO₂ below their thresholds at 0.84 layering ratio, 0.78 MPa adsorption pressure, 840s adsorption time and 5.3% P/F-ratio, at the expense of H₂ purity (77.1%) by breakthrough of CH₄, N₂ and O₂. Hydrogen purity was upgraded to >99.999% by EHP/C, which recovered 90.0% of hydrogen and simultaneously compressed to 20 MPa, which required 3.2 kWh/kg H₂. The overall VPSA-EHP/C recovery rate in this configuration was 81.5%. By utilizing the EHP/C retentate gas as VPSA purge gas, overall VPSA-EHP/C recovery rates may reach 87.3% and consume less energy due to a decrease in adsorption pressure. We show that adsorption columns designed to function as poisonous component eliminator are an effective strategy to pre-condition hydrogen synthesis gases prior to further processing with EHP/C. Although the EHP/C was exposed to significant concentrations of methane, nitrogen and oxygen by their advancement through VPSA, the performance was only slightly affected. The VPSA-EHP/C method is applicable to a wide range of hydrogen gas mixtures that require further purification and compression. Traditional PSA for purification from primary and by-product (COG, annealing, chlor-alkali and flat/float glass manufacturing) hydrogen sources can be changed to a VPSA-EHP/C systems for hydrogen purification and simultaneous compression.     

Simulation of integrated novel PSA/EHP/C process for high-pressure hydrogen recovery from Coke Oven Gas

This paper introduces a novel Coke Oven Gas (COG) hydrogen purification/compression system based on the technologies of Pressure Swing Adsorption (PSA) and Electrochemical Hydrogen Purification and Compression (EHP/C). As the EHP/C tolerates O₂, N₂ and CH₄ impurities, PSA can be utilized solely for CO and CO₂ removal (other COG impurities were not considered in this work). A relaxation of PSA hydrogen purity could significantly enhance its recovery rate. In this study, the suitability of traditional hydrogen PSA as part of the hybrid PSA/EHP/C approach was investigated. Aspen Adsorption and Matlab were used to model the PSA and EHP/C systems, respectively. The effect of adsorption pressure, purge-to-feed-ratio (P/F-ratio) and adsorption time within cycle on PSA performance is reported. This study found that breakthrough of non-detrimental components is typically accompanied with poisonous CO. Hence, the CO removal with traditional H₂-PSA resulted into high purity product. In a two-bed PSA, 36.3% of hydrogen was recovered at 99.9988% purity and 0.18 ppm CO. Subsequently, as a result, the EHP/C purification capability was merely utilized, but polished this hydrogen to >99.999% purity. Simultaneously, hydrogen was isothermally compressed to 20 MPa, consuming a marginal 2.42 kWh/kg. Compared to mechanical compression, this is 31.6% more energy efficient. Recovering hydrogen from by-product COG was found to save 0.5 kg CO₂/kg H₂ compared to hydrogen produced from natural gas. Conventional hydrogen PSA, utilizing 70% Activated Carbon and 30% Molecular Sieve 5A, was found not to be effective to target the removal of CO specifically. To increase synergy between PSA and EHP/C, the PSA requires adequate design and operation using appropriate adsorbents and cycle steps to target elimination of CO. An increased EHP/C catalyst tolerance for CO also contributes to higher flexibility.     

Modeling study on a two-stage hydrogen purification process of pressure swing adsorption and carbon monoxide selective methanation for proton exchange membrane fuel cells

A two-stage hydrogen purification process based on pressure swing adsorption (PSA) and CO selective methanation (CO-SMET) is proposed to meet the stringent requirements of H₂-rich fuel for kW-scale skid-mounted or distributed proton exchange membrane fuel cell systems. The reforming gas is purified using dynamic adsorption model of PSA with activated carbon for initial purification and then kinetic model of CO-SMET with 50 wt% Ni/Al₂O₃ for CO deep removal. Sensitive analyses of the gas hourly space velocity, adsorption time and adsorption pressure etc. are studied. The results show that excellent H₂ purity and CO concentration below 1000 ppm for the initial target using the three-bed and four-bed PSA system at shorter adsorption time and higher pressure, and then CO concentration below 10 ppm with H₂ purity over 99.94% on CO-SMET. This work provides a small-scale and hydrogen-saving process for hydrogen purification can be achieved by the two-stage process.