问题 问答题 简答题

蒸汽中杂质对机炉设备的安全经济运行有何影响?

答案

参考答案:

杂质沉积在过热器管壁上,会使传热能力降低,轻则使蒸汽吸热减少,排烟温度增高,锅炉效率降低,重则使管壁温度超过金属允许的极限温度而使管理子烧坏、如果沉积在蒸汽管道的阀门处,可能引起阀门动作失灵以及阀门漏沉,如果沉积在汽轮机的通流部分,则使蒸汽的通流截面减少,叶片粗造度增加,甚至改变叶片型线,而使汽轮机的阻力损失增加,出力和效率降低,另外还将引起汽轮机振动造成事故。

判断题
单项选择题

At the tail end of the 19th century, Friedrich Nietzsche suggested that natural history— which he saw as a war against fear and superstition-ought to be narrated "in such a way that everyone who hears it is irresistibly inspired to strive after spiritual and bodily health and vigour," and he grumbled that artists had yet to discover the right language to do this. "None the less," Nietzsche admitted, "the English have taken admirable steps in the direction of that ideal... the reason is that they [natural history books] are written by their most distinguished scholars—whole, complete and fulfilling natures. "
The English language tradition of nature writing and narrating natural history is gloriously rich, and although it may not make any bold claims to improving health and wellbeing, it does a good job—for readers and the subjects of the writing. Where the insights of field naturalists meet the legacy of poets such as Clare, Wordsworth, Hughes and Heaney, there emerges a language as vivid as any cultural achievement.
That this language is still alive and kicking and read every day in a newspaper is astounding. So to hold a century’s worth of country diaries is, for an interloper like me, both an inspiring and humbling experience. But is this the best way of representing nature, or is it a cultural default Will the next century of writers want to shake loose from this tradition What happens next
Over the years, nature writers and country diarists have developed an increasingly sophisticated ecological literacy of the world around them through the naming of things and an understanding of the relationships between them. They find ways of linking simple observations to bigger issues by remaining in the present, the particular. For writers of my generation, a nostalgia for lost wildlife and habitats and the business of bearing witness to a war of attrition in the countryside colours what we’re about. The anxieties of future generations may not be the same.
Articulating the "wild" as a qualitative character of nature and context for the more quantitative notion of biodiversity will, I believe, become a more dynamic cultural project. The re-wilding of lands and seas, coupled with a re-wilding of experience and language, offers fertile ground for writers. A response to the anxieties springing from climate change, and a general fear of nature answering our continued environmental injustices with violence, will need a reassessment of our feelings for the nature we like—cultural landscapes, continuity, native species-as well as the nature we don’t like—rising seas, droughts, "invasive" species.
Whether future writers take their sensibilities for a walk and, like a pack of wayward dogs unleashed, let them loose in hills and woods to sniff out some fugitive truth hiding in the undergrowth, or choose to honestly recount the this-is-where-I-am, this-is-what-I-see approach, they will be hitched to the values implicit in the language they use. They should challenge these. Perhaps they will see our natural history as a contributor to the commodification of nature and the obsessive managerialism of our times. Perhaps they will see our romanticism as a blanket thrown over the traumatised victim of the countryside. But maybe they will follow threads we found in the writings of others and find their own way to wonder.

It can be concluded that the tone of the passage is basically ______.

A.assertive and radical

B.explicit and straightforward

C.neutral and impartial

D.implicit and explorative