Unit1
(1) Chemical Engineering化学工程
Chemical engineering is defined as “…the application of the principles of the physical sciences, together with the principles of economics and human relations, to fields that pertain directly to processes and process equipment in which matter is treated to effect a change in state, energy content, or composition …”. 化学工程的定义是：将自然科学原理与经济规律和人际关系一起应用到与工艺或工艺设备直接相关的领域，在这些领域中物料的状态、能量或组成发生变化。
This very vague[veig] definition is intentionally broad and indefinite as to the extent of the field. It is probably as satisfactory a definition as any practicing chemical engineer would give. It should be noted that considerable emphasis is placed on the process and process equipment. The work of many chemical engineers would better be called process engineering. 这种极不明确的定义故意夸大或模糊了此领域的范围。可能任何一个有经验的化学工程师都能给出一个令人满意的定义。需要指出的是，强调的重点应放在工艺或工艺设备上。因此，许多化学工程师的工作最好称为过程工程。
The process may be any collection of steps involving changes in chemical composition or involving certain physical changes in material being prepared, processed, separated, or purified. （这种过程可能是任何步骤的组合，这些步骤包括要制备的、分离的或提纯的物料的化学组成变化或一定的物理变化。）
The work of many chemical engineers involves choosing the appropriate steps in the appropriate order to formulate a process for accomplishing a chemical manufacturing operation, a separation, or a purification.（许多化学工程师的工作包括选择合适的步骤，这些步骤按适当的顺序描述完成一个化学生产操作、分离或提纯的过程。）
Since each of the steps constituting a process is subject to variations, the process engineer must also specify the exact conditions under which each step is to be carried out.（由于组成一个过程的每一步骤都含有变化影响，因此，工艺工程师还必需确定完成每一个步骤的准确条件。）
As the process evolves and equipment must be designed, the work of the chemical engineer merges with that of the mechanical and civil engineer.由于需要改进工艺并设计设备，化学工程师的工作就与机械工程师和土木工程师的工作紧密结合在一起。
The transfer of primary responsibility from the process engineer to the mechanical[mik] engineer can take place satisfactorily at various stages of the design, so it is impossible to define a fixed extent to which the responsibility should be called that of a chemical engineer or a stage at which the mechanical engineer should take over responsibility for equipment.由工艺工程师到机械工程师主要职能的转变，可以在设计的任何阶段很自然地发生，所以很难找出一个特定领域说它是化学工程师的职责，或者找出一个阶段完全由机械工程师负责设备。
At the time the definition quoted above was presented, the physical sciences referred to were primarily chemistry and some classical[klesikEl] physics. As the understanding of mathematical models of chemical processes advances, the treatment of the chemistry and physics of the process is expressed in considerably more mathematical form. 上面引用的定义提出时，所说的自然科学主要是指化学和经典物理学。随着人们对数学模型和化学过程理解的不断深入，化学和物理过程的处理则多倾向于数学形式。
Increasing use of thermodynamics, fluid dynamics, and mathematical techniques such as probability and statistics, matrix manipulation, and complex variables is characteristic of modern chemical engineering practice. 热力学、流体力学和概率与统计、矩阵变换、复变函数等数学技术的日益广泛应用，是现代化学工程实践的特点。
In most processes being carried out on a large scale, however, the chemistry has been previously worked out, and the physical changes incident to separation and purification of the reaction mixtures demand considerably more study than does the chemical reaction. 在大规模进行的许多生产过程中，虽然化学过程早已完成，但与反应混合物处理和提纯有关的物理变化需要比化学反应进行更深入的研究。
Frequent application of the principles of physics and of physical chemistry is required in the processing steps that produce physical changes, such as vaporization, condensation, or crystallization. 在蒸发、冷凝、结晶这些能引起物理变化的过程中，常用到物理和物理化学原理。
As a process evolves into a plant and the work merges with that of mechanical designers, the science of mechanics becomes increasingly important. 随着某一工艺的工业化和工作与机械设计人员的日益结合，机械科学变得非常重要。
The chemical engineer who specialize in equipment must have thorough and extensive grounding in mechanics of materials. 设备专业的化学工程师必须在物料的机械性能上受过透彻、广泛的训练。
All of an engineer’s work must be quantitative, and mathematics is therefore a fundamental tool of the engineer. 所有工程师的工作必须是定量的，因此，数学是他们的基本工具。
Unfortunately, our understanding of mathematics is largely restricted to the domain of linear mathematics, and, equally unfortunately, chemical molecules seldom behaved in accordance with linear mathematical rules.但遗憾的是，人们对数学的理解在很大程度上局限于线性代数的领域，然而，化学分子的行为很少符合线性代数的规律。
Energy and material balance calculations, which are fundamental to any process study, can usually be expressed with confidence and precision in terms of linear mathematics, as long as we omit atomic and nuclear processes from our considerations.能量和物料衡算，是研究任何过程的基础。当忽略原子和原子核之间的作用时，它们可以根据线性代数用置信度和精确度来表示。
In the economic study to determine the most profitable operating conditions-and in accounting for the sales receipts and distribution of income to profits and costs, including replacement of the plant-mathematical calculations are universal. 在确定最适宜操作条件的经济评价中，在解释销售收入和收入在效益和支出的分配（包括更换新设备）中，数学计算的应用十分普遍。
The existence or contemplation of a process implies that a material is to be produced for which customers will pay. It must be delivered in a quantity, of a quality, and at a price which are acceptable to the customer . 一个工艺过程的存在和规划都意味着必须生产某种顾客可以接受的产品，该产品在交货时必须符合一定的数量的质量，且价格也可以被顾客所接受。Simultaneously, it must pay for materials, labor, and equipment used in the manufacture and return a profit over and above all cost. 同时，还必须付出原料、劳动力和设备制造的费用，并且在除去所有费用后还要获得利润。
Many materials produced by the chemical industry are planned and plants built before the real market potential has been developed.化学工业生产的许多产品都是有计划的，工厂在真正的市场潜力形成以前已经建成。
For a completely new product, some estimate of the size of the market must be made, and the plant should be scaled in proportion. 对一个全新产品而言，必须对市场前景做充分估计，工厂的规模要适当。
The human-relations aspect of engineering practice is not usually emphasized in undergraduate training because of the great quantity of techniques the student must learn. 因为学生们需要学习大量技术信息和技术，因此，大学期间很少强调工程实践中的人际关系问题。
That this may be a fallacious course is implied by the fact that failures of young engineers because of personnel problems are at least five times as frequent as failures because of inadequate technical training. 许多年轻的工程师，由于自身原因，缺乏足够的技术训练，在工作中就会频繁出错。这上事实说明，这种课程安排是不合理的。
All engineers must realize that the industry in which they are working requires team effort of all personnel. 所有工程师都应该意识到他们所从事的工作需要所有人共同努力。
Valuable information can be obtained form operators of limited educational background who have observed similar processes.
