Unit 5Basic Chemicals
基本化学品
We can divide the various sectors of the chemical industry into these two types: the higher-volume sector and low-volume sector. In the high-volume sector, individual chemicals are typically produced on the tens to hundreds of thousands of tonnes per annum scale. As a result, the plants used are dedicated to the single product, operate in a continuous manner and are highly automated, including computer control. Sectors categorized as high-volume are sulphuric acid, phosphorus-containing compounds, nitrogen-containing compounds, chlor-alkali and related compounds, plus petrochemicals and commodity polymers such as polythene. With the exception of the latter, they are key intermediates, or base chemicals, which are feedstocks for the production of a wide range of other chemicals, many of which are also required in large quantities.
我们可以将化学工业的不同部分分成两种类型：高产量部分和低产量部分。在高产量部分各自的化学制品通常以每年几万到几十万的规模来生产。结果，工厂只出产唯一的产品，操作以连续的方式被高度自动化，包括电脑控制。归类于高产量的部分有硫酸，含磷化合物，含氮化合物，还有碱的制备和有关化合物，还有石油和农用地聚合物像聚乙烯。除后者之外，其它的都是重要的媒合物或是基础化学品，它们更是其它一系列化学产物生产的原料，它们当中的许多被大量的需求。
In contrast, low-volume sectors are largely involved in fine-chemicals manufacture, and individual products are produced only on the tens of tonnes to possibly a few thousand tonnes scale. However, they have a very high value per unit weight, in contrast to high-volume products. Fine chemicals are usually produced in plants operating in a batch manner and the plants may be multiproduct ones. Thus, low-volume sectors are agrochemicals, dyestuffs, pharmaceuticals, and speciality polymers such as PEEK.
对比来看，低产物部分主要包括精细化学品的生产，并且个别产品仅仅以几百到几千的规模生产。然而，它们每单位产量饿价值与高产量产品比较要高的多。精细化学品通常在工厂以批量生产的方式生产，并且工厂是联产的。因此，低产量的部分由农业化学品，染料，药品和特殊的聚合物像聚醚醚酸。
基础化学品在化学工业中得不到支持，它们不那么引人注意（如药品），有时候利润不很高。其利润来自于经济盛衰时难以预测的周期。
这些基本化学品不被公众注意到和直接使用，因此其重要性常得不到理解。即使在化学工业中，其重要性也得不到足够的重视。然而，如果没有这些基本化学品，其他工业就不复存在。 基本化学品处于原料（及那些从地下通过采矿、开采或用泵抽出来的物质）和最终产品的中间位置。
基本化学品的一个显著的特征就是它们的生产规模，每一种（基本化学品）的生产规模都相当大。图2-1表示在1993 年美国市场上的25 中化学品。（为了使我们了解化学品的分类与生产量有关。）通常，基本化学品生产于那些年产量上万吨的工厂。年产量10 万吨的工厂每小时要生产1.25 吨。基本化学品的另一显著重要的特征是其价格。大多数价格相当便宜。
基本化学品工业所作的工作（或任务）是找到经济的途径将原来转变为有用的中间体。生产厂家要对它们的产品收取较高的价格几乎没有余地，因此，那些最低费用生产产品的厂家可
能获得的利润最高。这就意味着，厂家就必须不断准备寻求新的，更经济的生产和转变原料的方法。许多基本化学品为石油精炼的产物，而部分基本化学品工业----硫、氮、磷和氯碱工业是把除C 和H、S 外的元素转变为化学品。总之，这些产品和石化工业的基本产物两者结合起来可生产无数重要的化学物质，这些重要的化学物质可作为其余化学工业的原料。
基本化学工业现在面临着其历史上中最大的挑战之一，该工业中的产品消费部门---农业以停止增长。同时大大减小了对肥料的需求。西方的农场主生产了大多的食物，政府减小了对农业部门的津贴，结果导致了更少的土地用于耕种和所需的肥料减少。过量肥料的流失而引起的环境的关注也减少了对肥料的需求。诸如含氯化合物之类的产品，已收到了来自环境学家的压力。根据《关于消耗臭氧层物质的蒙特利尔白皮书》，一些产品将受到禁止。而其它的物质，可以受得住环境学家的压力。基本化学品工业再也不会 依靠在需求量方面的长期增长。
为了实现更好的规模经济和某一特殊产品更好的市场地位，厂家相互交换工厂（车间），该工业注重不断合并联合。这使从事某一工业的人员减少，使该工业达到更好的供需平衡和更好的利润。基本化学品工业正逐渐转向为其他化学工业服务，而越来越小地为农业服务。
基本化学品受到的压力是许多大规模过程引起的（觉察得到的）较大的环境污染。尽管许多大厂家的生产效率较高，但是该工业要实现最好的环境标准还有很长的路要走。增加重复利用的驱动力和理想化的无排放的工厂，是影响接下来十年该工业发展的主要因素。
技术的进步不会停止，我们将日益重视无污染的工厂和过程。厂家将在效率上展开竞争。那些能以最低的成本生产最高质量产品的厂家将繁荣昌盛。这需要厂家在技术改进方面保持投资。基本化学品的合成有用的中间体的新颖方法将不断被人们发现。在基本化学品工业中，仍然还有许多工作有待去做。
UNIT 6
Historically the bulk chemical industry was built on chlor-alkali and related processes．The segment is normally taken to include the production of chlorine gas，caustic soda(sodium hydroxide)，soda．ash(derivatives of sodium carbonate in various forms)and，for convenience，lime-based products．
从历史上来讲，大规模的化学工业都是建立在氯碱及其相关工业上的，通常这部分都包括氯气，氢氧化钠，纯碱，（各种不同形式的碳酸钠）的生产。简而言之，这些都是含石灰的产品. Soda—ash and sodium hydroxide have competed with each other as the major source of alkali ever since viable processes were discovered for both．The peculiar economics of electrolytic processes mean that you have to make chlorine and caustic soda together in a fixed ratio whatever the relative demand for the two totally different types of product，and this causes swings in the price of caustic soda which can render soda—ash more or 1ess favorable as an alkali．
纯碱和氢氧化钠作为碱的重要原料从可行性工业开发出来就一直竞争。电解工业的特殊经济性意味着无论对这两种不同产品的相对需求如何,你都必须以一定的比例同时生产氯气和烧碱.这就引起了烧碱的价格浮动。这样会使纯碱作为碱或多或少受到欢迎。
Both chlorine/caustic soda and soda—ash production are dependent on cheap readily available supplies of raw materials．Chlorine caustic soda requires a ready supply of cheap brine and electricity, soda-ash requires brine，limestone and lots of energy．Soda-ash plants are only profitable if their raw do not have to be transported far. The availability of such supplies is a major tractor in the location of many of the chemical industry‘s great complexes. 氯气和纯碱的生产依赖于原料的价格低，易于获得，纯碱需要海水，石灰石和大量的能量，如果原料离工厂不是很远，是能获利的。许多化工联合企业在选择厂址的复杂问题中，都把原料易于供应作为重要因素。
1.Lime-Based Products主要原料是
One of the key raw materials is lime．Limestone consists mostly of calcium carbonate (CacCO3) laid down over geological time bt various marine organisms. High-quality lime stones are often good enough to be used directly as carbonate in further reactions. Limestone usually mined in vast open-cast quarries, many of which will also carry out some processing of the materials.
主要成分是碳酸钙的石灰石.他是由各种海洋生物经过地质时代变迁形成的.高质量的石灰石通常可以用来作为碳酸钙进一步的反应.石灰石通常在露天的采石场开采.许多采石场也对这些原料进行加工。
The two key products derived form limestone are quicklime (CaO) and slaked lime Ca (OH)2 . Quicklime is manufactured by the thermal decomposition (1200 ~ 1500C) of limestone according to the equations: CaCO3→CaO+CO2
从石灰石衍生出的两种重要产物是生石灰和熟石灰，生石灰是通过在1200到1500摄氏度的温度下热分解石灰石 得到的，是根据下面的这个反应；
Typically limestone is crushed and fed into the higher end of a sloping rotating kiln where the decomposition takes place and quicklime is recovered from the end．Most frequently, however, the quick time is not isolated for further reactions，rather, other compounds arc fed in with the lime to give final products at the tow end of the kiln. For example, alum in a iron ore and sand can be fed in to give Portland cement. Soda-ash manufacture often adds coke
to the limestone which buns to give extra carbon dioxide needed for soda-ash manufacture. Slaked lime which is more convenient to handle than quicklime-is manufactured by reacting quicklime with water.
一般情况下, 石灰石经过粉碎进入一个高点的最终倾斜的回转窑发生分解, 在那里最终被转化成石灰石. 多数情况下, 生石灰不被分离发生进一步反应. 因此其他的化合物和石灰石一起加进低的反应窑来生成最终产物. 例如,铝土,铁矿,和沙子能够被加进去生产硅酸盐水泥. 纯碱的生产通常要在石灰石中加入焦炭, 进行燃烧来生产纯碱所需要的额外的二氧化碳。熟石灰要比生石灰处理起来更方便, 他是由生石灰加水反应得来的。
About 40％of the output of the lime industry goes into steel-making, where it is used to react with the refractory silica present in iron ore to give a fluid slag which floats to the surface and is easily separated from the liquid metal．Smaller, but still significant, amounts are used in chemical manufacture, pollution control and water treatment. The most important chemical derived from lime is soda—ash.
大约40%的石灰石工业生产的产品用来炼钢。在炼钢过程中她用来和铁矿中耐火的二氧化硅发生反应得到矿渣。这些矿渣漂浮在表面并且很容易和液态金属分离。较少量但很重要的用来化工生产污染控制和水处理来至于石灰的最重要的化学品是纯碱。
2．Soda-Ash
The Solvay process．The process，which was perfected by Ernest Solvay in l 865，is based on the precipitation of NaHCO3 when an anamoniated solution of salt is carbonated with CO2 from a coke-fired lime kiln. The NaHCO3 is filtered, dried, and calcined to Na2CO3. The filtered ammonium chloride process liquoris made alkaline with slaked lime and the ammonia is distilled out for recycle to the front end of the peocess. The resultant calcium chloride is a waste or by—product stream.
索尔维工艺，该工艺发现于1965 年由ES 优化：工艺是以当含氮的盐溶液经来自于石灰窑中焦炭燃烧产物CO2 碳酸盐反应时，NaHCO3 沉淀析出为基础。NaHCO3 经过滤、干燥、煅烧生成CaCO3。过滤后NH4Cl溶液和熟石灰反应后（溶液体呈碱性）。蒸馏出NH3 在该过程中循环利用，生成物CaCl2 是废弃物或副产物。
For a simple basic product the Solvay process appears exceedingly complicated．The basic principle of the reaction is to take salt(NaCl)and calcium carbonate(CaCO3)as inputs and to produce calcium chloride and sodium carbonate as outputs．However，the reactions occurring between input and output are not remotely obvious and involve the use of ammonia and calcium hydroxide as intermediate compounds.
对于某一简单的基本产物来说,索尔维法看起来十分复杂。该反应的基本原理是,以NaCl2 和CaCO3为原料生成产物CaCl2 和Na2CO3.然而发生于原料和产物之间的反应并不明显,需要利用NH3 和Ca(OH)2作为中间化合物。
The essential principle is that，by carefully controlling the concentration of the components (especially…salt)，sodium bicarbonate can be precipitated from solutions containing calt, carbon dioxide and ammonia．The key to making the process work is controlling the strength of the solutions and the rates of crystallization.
该过程的基本原理为:利用准确的控制组分（尤其是NH3 和NaCl）的浓度,NaHCO3 能够从含NaCl、CO2 和NH的溶液里沉淀析出。该过程的关键是控制溶液的酸碱强度和结晶的速度.
The essential steps of the process are as follows．Ammonia is absorbed in an anlmonia absorber into brine which has previously been purified to reduce the amount of calcium and magnesium ions(which…plpe-work). The solution (nominally...hydroxide) is then passed down a tower where it absorbs carbon dioxide (passing …tower) to form ammonium carbonate at first and later ammonium bicarbonate．By the next stage of the plant sodium chloride and
相关推荐：
loading