中国化工行业的展望

Perspective Chemical Engineering in China: Past, Present and Future Yong Jin and Yi Cheng Dept. of Chemical Engineering, Tsinghua University, Beijing 100084, P.R. China DOI 10.1002/aic.12570 Published online February 3, 2011 in Wiley Online Library (wileyonlinelibrary.com). Keywords: chemical engineering, chemical industry, education, clean coal conversion, low-carbon technology Introduction The modern chemical industry experienced its genesis in the 19th century, and rapid development in the 20th, thereby achieving significant impact on the progress of human civili- zation. The Solvay process in 1870s marked a milestone in the deployment of continuous processes with integrated plant-wide considerations, while the commercialization of the ammonia synthesis process in the 1920s marked the first science-based landmark process in the modern chemical industry. Subsequent milestones were made possible by the successful application of techniques such as fluidized cata- lytic cracking in the refining industry, solvent extraction in the nuclear fuels industry, precision separation in the produc- tion of heavy water, submerged culture of microorganisms in the mass production of penicillin, etc., which all occurred in the 1940s. At the end of 1960s, the integration of chemical process systems engineering methodologies and computer control techniques established the foundation for the large- scale modern chemical enterprise. Advances in conceptual/ biological design, operation and control of prokaryotic and mammalian biochemical processes, and synthesis techniques for new materials such as ultra-pure semiconductor materials and nanomaterials in the 1990s, have been at the core of an exploding high-tech chemical industry we have witnessed in the last 30 years. Along with the global development in chemical engineer- ing, the Chinese chemical industry also experienced major changes in the past century. As a large country with 1.3 bil- lion people, the huge demand for basic and specialty chemi- cals led to broad market prospects, and, therefore, facilitated the fast development of the chemical industry, and promoted the advancement of education, research and development in chemical engineering. It must be acknowledged, however, that there is a funda- mental difference in the rate and the modes of overall devel- opment in chemical engineering between China and the devel- oped countries. As one of the backbone industries that sup- ported the rapid growth of Chinese economy, the chemical industry in China and its related education and research activ- ities, for historical reasons underwent fast development only in the past 30 years, compared to a century-long progress in the developed countries. At present, China has excellent opportunities for closing the gap with the rest of the world, but also faces immense sustainability challenges in terms of energy, resources, and the environment. At the same time, industrial development requires a large supply of highly edu- cated chemical engineers and enhanced capabilities in research and development. The objective of this Perspective is to provide a brief account of the historical development, pres- ent challenges, and future trends in the Chinese chemical industry and the discipline of chemical engineering. Beginnings of the Chinese Chemical Industry Until the 1980s, the chemical industry in China was still in its infancy. In light of the basic demand of feeding up to 20% of the world’s population (1.3 billion) using only 7% of the world’s arable land, the chemical industry, naturally, focused its attention in the production of chemicals (fertil- izers, pesticides, herbicides) to support rapid expansion of Chinese agriculture. However, while chemical fertilizers should have ensured the required increase in the crop yield per unit area, especially in the Loess Plateaus, China’s main farmlands, limited by the low levels of engineering and tech- nological foundations underpinning the chemical industry, and the inadequate levels of engineering education at the time, the amount of produced fertilizers did not meet the demand, their production caused heavy pollution and involved a wasteful utilization of resources. Simultaneously, the chemical industries involved in manu- facturing acids (e.g., H2SO4, HCl, HNO3), and alkalis (e.g., NaOH, Na2CO3) increased their capacity in order to meet the basic requirements of the paper, glass, and nonferrous metal industries, among others. In order to balance the large Correspondence concerning this article should be addressed to Y. Jin at jiny@ tsinghua.edu.cn. VVC 2011 American Institute of Chemical Engineers 552 AIChE JournalMarch 2011 Vol. 57, No. 3 amount of byproduct chlorine (Cl2) from a caustic soda industry, based on the salt electrolysis processes, the PVC industry was thereafter established. It must be noted that the ammonia synthesis and PVC industries both adopted proc- esses starting from coal as the major feedstock. Rapidly growing and expanding industrial experience and especially fast improving and diversifying professional edu- cation from the initial career stages, soon became corner- stones for the subsequent development of Chemical Engi- neering in China, which nevertheless lagged behind the world at that time. Fast Development of Chemical Engineering in the Past 30 Years Chemical and petrochemical industries Since the early 1980s, China began to import mature pe- trochemical process technologies from abroad. As a result, at this time, a number of integrated industrial complexes have been successfully established in China. In particular, the overall strength and competitiveness of the petrochemical industry have been significantly enhanced. The average an- nual rate of increase of product value at current prices, industrial added value and sales revenues are 21.25%, 18.28% and 21.50%, respectively, which are much higher than the rates of increase of GDP in China and the devel- oped countries during the same period. Today, China is the major manufacturer of chemical and petrochemical products in the world (see Table 1). The pro- duction volumes of several key chemical products are among the highest in the world, including the following: synthetic fibers, chemical fertilizers, soda, caustic soda, and PVC, in which the Chinese production is the highest in world; crude oil processing, ethylene, and synthetic resins, etc., where the Chinese levels of production hold the second position. The current production of petroleum refinery products, nitrogen fertilizers, phosphate fertilizers, soda, pesticides, and caustic Table 1. Production Volume for Major Chemical and Petro-chemical Products (3104t) AIChE Journal March 2011 Vol. 57, No. 3 Published on behalf of the AIChE DOI 10.1002/aic 553 soda has satisfied internal demand, while the production of inorganic salts, automobile tires, and others, and has exceeded domestic demand. In contrast, the production of ethylene, synthetic materials, chemical fiber materials, potas- sium fertilizers, and methanol does not satisfy domestic needs and is heavily supplemented by imports. Along with the expansion of gross production capacity in basic chemicals, technical indicators of capital efficiency, such as the plant capacity in the petrochemical industry, have been continuously improving. In 2008, 13 Chinese refineries had production capacity larger than 10 Mt/a, each, for a total production of 136 Mt/a; 42.6% of the total pro- duction in China. Plant capacity for ethylene production has increased to more than 450 kt/a, for each petrochemical plant. At the same time, several novel refining technologies were introduced for clean gasoline production with high- added value olefin byproducts. For example, a two-stage fluid catalytic cracking (FCC) technology, combining the functions of refining and propylene production, was devel- oped by researchers in the Chinese Petroleum University and has been successfully commercialized. The downer reactor, the so-called 21st century refining reactor technology, was first demonstrated in 2003, in Ji’nan refinery (SINOPEC) at a capacity of 150 kt/a. The essential idea in this technology is to utilize the favorable plug flow pattern and uniform flow structure in the downer reactor in order to achieve limited over-cracking and improved selectivity in a refining process. The corresponding research was carried out over a period of about 30 years in the Fluidization Laboratory of Tsinghua University (FLOTU).1–3 The demonstration unit implemented the flexible operation of a coupled riser and downer design by changing the feed positions and using high-severity operational conditions to intensify the cracking of petroleum cuts. Increased productivity, energy savings and emissions reduction have become the central goals of the petrochemi- cal industry and are driving science and technology develop- ment. In order to fulfill the national targets in China’s 11th five-year plan (2006–2010), the energy consumption quota in the petrochemical industry must decrease from 3.23 in 2005 to 2.58 in 2010, in terms of the standard coal consumption (i.e., the amount of heating value by different fuels equiva- lent to 7000 kCal/kg of standard coal) for power generation per 10 k RMB GDP. Obviously, major effort is required to meet this goal; a major driver for the advancement of the pe- trochemical industry and a visible measure in reducing CO2 emissions to address climate change. Limited resources have become a critical constraint to the current development of Chinese petrochemical industry. For example, in 2007 petroleum production in China was about 18.7 Mt, while the imported amount was about 16.3 Mt, and the apparent consumption was 34.6 Mt. Thus, the degree of external dependence was about 45%, and this figure has con- tinued to increase in the last three years. Coal chemical industry In 2006, coal supplied 70.2% of the energy consumed in China, with 23.5% coming from oil and natural gas, and 6.3% from other sources. This is in sharp contrast with the energy consumption structure in the rest of the world: Coal, 28.4%; oil and natural gas, 59.5%; other sources, 12.1%. To match the chemical industry’s development with the struc- ture of energy production/consumption in China, coal-based chemistry has been one of the major directions in the devel- opment of chemical industry. A large-scale clean coal pro- ject has become the focus of development efforts, with sig- nificant technological breakthroughs anticipated in its major processes. In addition to the urea industry, the production of methanol based on coal conversion is increasing dramati- cally, e.g., about 11 Mt in 2007. Currently, the consumption of methanol involves the production of formaldehyde, acetic acid, methyl tert-butyl ether (MTBE), alcohol ether fuel, pesticides, methylamine, and others. The extended range of methanol products, such as polyoxymethylene (POM), poly(- methyl methacrylate) (PMMA), pentaerythritol, cellulose ac- etate, organosilicon, etc., are also undergoing rapid develop- ment. The new technologies in the coal chemical industry such as MTO (methanol to olefins), MTP (methanol to pro- pylene), MTA (methanol to aromatics), and coal to SNG (substitute natural gas), are being developed at pilot-plant scale units, which frequently rise to units of industrial-scale production. Moreover, the pilot use of methanol and di- methyl ether (DME) as alternative fuels aims to partially mitigate the urgent demand for oil and has been tried in sev- eral cities in China. Since coal is an abundant natural resource in China, it is expected that a coal-based chemical industry will continue to play a pivotal role in China’s eco- nomic development and offers bright prospects for the future. Up to this time, more than 95% of China’s energy resour- ces have been domestic. For exported products such as the coke, calcium carbide, ferrosilicon, ferroalloy, aluminum in- got, polycrystalline silicon and so on, the scales of produc- tion are very large, but the added value in these products is very low. Since the amount of energy per unit of product needed in the production of these materials is rather large, export of these materials implies a kind of embedded energy export from China. It is estimated that during the period from 1997– 2007 the total amounts of imported and exported energy in China were roughly balanced. However, due to the high rates of industrial development, China’s eco-environ- mental burden has been increasing at substantial rates by heavy pollution. Fine chemicals and materials manufacture Concurrently with the aforementioned developments in the petrochemical and coal-based chemical industry, the produc- tion of fine chemicals has been also advancing with high rates of growth. In 2006, the produced value of fine chemi- cals in China was about 500–550 billion RMB, with the total volume of production at about 30 Mt/a, not including phar- maceuticals and veterinary drugs (see Table 2). However, it should be noted that these fine chemicals are not high-end products of high added value, and were pro- duced through technologies of rather low-level scientific and engineering content. In addition, the R&D capabilities of the corresponding companies are rather weak in the area of fine chemicals and cannot meet the demands associated with mass production of fine chemicals in the future. This weak- ness creates excellent opportunities for the collaboration of 554 DOI 10.1002/aic Published on behalf of the AIChE March 2011 Vol. 57, No. 3 AIChE Journal the specialty chemicals Chinese companies with foreign countries (companies; chemical, technology developing, product formulators, etc.), in the form of direct investments from abroad and collaborations on the development of cer- tain technologies and products. A similar situation exists in the advanced materials sector of the industry. Innovations in clean energy and low-carbon techniques Pollution control is one of the biggest problems associated with the fast development of the Chinese chemical industry. Detailed guidelines have been issued by the Chinese govern- ment, according to which the SO2 emission and COD (Chemical Oxygen Demand) index should be reduced by 10% along with a stable and rapid growth of GDP in the next five years. Since the necessary flue gas desulfurization devices and the new sewage treatment plants, expected to support the targeted improvements, have already been con- structed to a large extent, the desired targets should be achieved. At the same time it is fairly broadly accepted that the most rational route to implementing pollution control would be through innovative production technologies that lead to zero-emission process designs, especially for the coal-based segment of the Chinese chemical industry. The ENN Group, a private enterprise in China, has estab- lished an advanced research center where it has been pursu- ing effective integration of novel technologies and engineer- ing methodologies and in 2009 was able to realize coal- based, clean energy, zero-emission production technology at the pilot plant scale. Figure 1 shows the flow chart with the highlighted technologies in ENN Group’s research center. It is anticipated that this integrated approach of low-carbon technologies will lead to the successful incorporation of solar Table 3. Production of New Materials Table 2. Production of Fine Chemicals (2006) AIChE Journal March 2011 Vol. 57, No. 3 Published on behalf of the AIChE DOI 10.1002/aic 555 energy, wind energy, and biotechnology with the coal chemi- cal industry, in order to provide an effective solution to the carbon dioxide emission problem. Furthermore, the under- ground processes based on steam-oxygen gasification, coal catalytic gasification and methanation technologies are directed toward the development of clean and low-carbon processes which convert dirty coal to clean and low-cost energy. Another series of innovative technologies are targeting the clean production of PVC resins. In 2009, the annual produc- tion of PVC in China was about 12 Mt and was mainly based on the conventional carbon calcium route, which uses mercury as the major component of the catalyst that converts acetylene and HCl to VCM (vinyl chloride monomer, CH2CHCl), and causes severe pollution to the environment in terms of waste gas, dust/residue, and effluents of water and mercury. Since the carbon calcium production method starts from the coal to coke process, the PVC industry is in fact one of the coal conversion industries with large volume of annual production. As the first step to make acetylene from coal, coal pyroly- sis to produce acetylene in thermal plasma reactor has been explored in China for the past 10 years. This is actually a well-known technology discovered4,5 and developed6,7 in the period 1960–80s, but not commercialized due to limited market demand in that period and the difficulties associated with continuous operation over long time periods of such high-severity process. In this process, pulverized coal is injected into hydrogen plasma of ultra-high temperatures and supersonic flow velocities of more than several hundred meters per second. The conversion of coal to the desired acetylene product takes place in milliseconds, with hydro- gen, ethylene, methane, and CO, as the primary byprod- ucts.8–10 The attractive features of this process are: it is coal- based, clean, one-step conversion technology, without direct emission of carbon dioxide, and without the need for water as feedstock.11 At present, a demonstration pilot plant with the plasma power input of 5-MW, including reaction, separa- tion and the common facilities, has been successfully built and run for industrial testing by the Xinjiang Tianye Group. It is well-known that acetylene was the major feedstock for the synthetic chemicals’ industry for many years. Technological breakthroughs on the coal pyrolysis process using plasma would result in the revitalization of the acety- lene industry, an attractive prospect considering the continu- ously increasing prices and comparative scarcity of oil resources. Following the clean production of acetylene, a mercury- free process to synthesize VCM is being explored in China with financial support from the government and PVC-pro- ducing companies. Two reasons drive the development of mercury-free production technologies: eliminate the adverse pollution effects from production process effluents containing mercury; eliminate reliance on mercury whose world-wide resources are being exhausted rapidly. It is expected that this novel process would be successfully commercialized within five to 10 years. Successful completion of the aforemen- tioned two novel process technologies would lead to the rewriting of production technology textbooks’ chapter on the production of PVC, a production process that started from coal. As a further extension to the PVC product chain, a novel gas–solid contacting process to make chlorinated PVC (CPVC) in a clean way has been under development, using cold plasma as the initiator of the chlorination process, which is quite distinct from the conventional aqueous-sus- pension method that produces significant amounts of unavoidable pollution. There are two important reasons for pursuing large-scale commercialization of chlorinated PVC. First, CPVC has many superior characteristics when com- pared to PVC, e.g., it is thermally more stable and superior as flame retardant, and as a result offers a product with higher net added value. Second, the production of CPVC uti- lizes excess chlorine gas from the chloro-alkali industrial production network and incorporates it into the solid-state CPVC resins; a net effect of great significance for the chlo- rine balance in China. Figure 2 shows the vision of a future production network for the clean PVC production with several technology innovations in the core processe