A comparative study on the energy efficiency levels of major energy-consuming products in the chemical industry at home and abroad

Thread Content

I. Energy consumption in China’s chemical industry In 2007, the petroleum and chemical industry consumed 375 million tons of standard coal in terms of energy use, accounting for 15.2% of the country’s total energy consumption. Among them, the chemical industry consumed 250 million tons of standard coal, accounting for 10.1% of the country’s total energy consumption. 　　Synthetic ammonia, caustic soda, calcium carbide, and yellow phosphorus are key energy-intensive products in the chemical industry, accounting for over 43% of the industry’s energy consumption. In 2007, the energy consumption for synthetic ammonia was 75 million tons of standard coal, accounting for 30% ； The energy consumption for caustic soda is 12 million tons of standard coal, accounting for 4.8% ； The energy consumption for calcium carbide is 1,800 tons of standard coal, accounting for 7.2% ； Yellow phosphorus consumes 0.035 billion tons of standard coal, accounting for 1.4%. 　　II. Comparison of energy consumption levels for major energy-intensive products in the chemical industry at home and abroad In 2007, the overall energy consumption per unit of these key energy-intensive products in the chemical industry decreased to varying degrees. Among them, the standard coal consumption per ton of synthetic ammonia was 1,421.68 kg, a decrease of 4.1% compared with the previous year. The comprehensive energy consumption for caustic soda was 501.78 kg of standard coal, representing a 2.78% decrease compared to the previous year ； Among them, for the 30% produced by the ion-exchange membrane process, the standard coal consumption per ton of alkali was 386.37 kg, a decrease of 0.54% compared to the previous year ； The standard coal consumption per ton of alkali produced by the 30% diaphragm method is 768.38 kg, a decrease of 2.7% compared to the previous year. The standard coal consumption per ton of calcium carbide was 1,107.26 kg, a decrease of 2.96% compared to the previous year. Overall, the energy consumption levels of these four major energy-intensive products in China’s chemical industry – synthetic ammonia, caustic soda, calcium carbide, and yellow phosphorus – are still somewhat behind those of advanced countries abroad, although this gap is gradually narrowing. 　　In recent years, the criteria for calculating energy consumption in China have changed. To facilitate comparisons between domestic and international figures, we selected data from 2005, whose calculation criteria are relatively similar, for comparative analysis. Compared with advanced foreign levels, the energy consumption of several major energy-intensive products in our country is higher: the energy consumption per unit of synthetic ammonia is on average 14%-23% higher, that of caustic soda is 8%-18% higher, that of calcium carbide is 15%-21% higher, and that of yellow phosphorus is 6% higher. The order of the magnitude of the gaps is: synthetic ammonia, calcium carbide, caustic soda, and yellow phosphorus. In our country as well, some products have achieved energy consumption levels that are equal to or close to international advanced levels thanks to improvements in raw materials or production processes. Examples include synthetic ammonia produced by large-scale ammonia plants that use natural gas as a raw material, caustic soda manufactured via the ion-exchange membrane process, large-scale closed-circuit calcium carbide production facilities, and large-scale yellow phosphorus production. 　　A comparison of the energy consumption levels of the main energy-intensive products in the chemical industry at home and abroad is shown in Tables 1 and 2. 　　Appendix 1: Energy consumption per unit of several high-energy-consuming products in the domestic and international chemical industries in 2005
Product, Domestic average level, Statistical method abroad, Advanced technologies used abroad, Advanced level of that country

Comprehensive energy consumption for ammonia synthesis (natural gas), kgce/t: 1392; Kellogg Company, USA – 1000. Abroad: Process design value; Domestically: Also includes allocation from auxiliary and associated processes. Rational use of energy at different levels, pressurized conversion of feed gas, advanced purification technologies, reduced synthesis pressure, new catalysts.

Comprehensive energy consumption for ammonia synthesis (coal), kgce/t: 1847; Texaco Technology, USA (design by Ube in Japan) – 1613. Abroad: Process design value; Domestically: Also includes allocation from auxiliary and associated processes. Advanced coal gasification technologies, advanced purification technologies, reduced synthesis pressure, new catalysts.

Electric energy consumption for liquid caustic soda production (diaphragm process), kgce/t: 2678*; Western Chemical Company, USA – 2459. Abroad: Measured value; Domestically: Statistical value. Improved membrane performance and electrolyzers.

Comprehensive energy consumption for caustic soda production (ion exchange membrane process), kgce/t: 1067; Asahi Kasei Corporation, Japan – 980. Abroad: Measured value; Domestically: Statistical value. Improved membrane performance and electrolyzers.

Comprehensive energy consumption for caustic soda production (diaphragm process), kgce/t: 1478; Hooker Company, USA – 1250. Domestically: Also includes allocation from auxiliary and associated processes. Improved membrane performance and electrolyzers.

Comprehensive energy consumption for calcium carbide production, kgce/t: 2185; Companies from the US, Germany, and Japan – 1800. Domestically: Also includes allocation from auxiliary and associated processes. Closed calcium carbide furnaces, hollow electrodes, recovery of heat from furnace gases, automation.

Comprehensive energy consumption for yellow phosphorus production, kgce/t: 7400; Companies from the US, Germany, and Japan – 7000. Abroad: Measured value; Domestically: Statistical value. High level of automation and efficient utilization of resources.

Note: 1. *The electric energy consumption value for the diaphragm process represents the ideal value obtained by converting the domestic statistical figure to match the same current density as abroad (2150 A/M2). 　　2.1 kWh = 0.404 kgce. Appendix 2: Comparison of energy consumption per unit of several high-energy-consuming products in the domestic and international chemical industries. Comprehensive energy consumption (kgce/t): Domestic average (1), Internationally advanced level (2); Percentage difference = (1)/(2)%. Synthetic ammonia (natural gas, large-scale): 1233, 1000 (minimum 930); +23.3%. Synthetic ammonia (coal): 1847, 1613; +14.5%. Caustic soda (diaphragm process): 1478, 1250; +18.2%. Caustic soda (ion exchange membrane process): 1067, 980; +8.8%. Calcium carbide: 2185, (1215) *; 1800, (940) *; +21.3%. Yellow phosphorus: 7400, (3400) *; 7000, (3200) *; +5.7%. Note: 1 kWh = 0.404 kgce; for calcium carbide and yellow phosphorus, the value in parentheses is calculated using 1 kWh = 0.1229 kgce.

III. Analysis of the reasons behind the differences in energy consumption levels of major energy-consuming products in the domestic and international chemical industries

1. Resource conditions
The most prominent characteristic of China’s energy resources is an abundance of coal, a shortage of oil, and limited natural gas reserves. China’s proven coal reserves account for about 12.6% of the world’s total, and at the current rate of extraction, these reserves will last for approximately 100 years. However, proven reserves of crude oil account for only 1.4% of the world’s total, while those of natural gas account for 1.2%; both are scarce resources. At present, the composition of energy production in our country is roughly as follows: coal accounting for about 75%, crude oil about 13%, and natural gas 3%-4%. From the perspective of energy supply and demand, China’s dependence on imports for crude oil consumption is increasing year by year, rising from 42.4% in 2005 to nearly 50% in 2008, resulting in increasingly prominent supply-demand imbalances and market risks. As a clean energy source, natural gas is produced in a stable manner; however, as demand rises for its use in household applications, power generation, and petrochemical industries, the imbalance between supply and demand is becoming increasingly severe. This situation determines that the final energy consumption structure of our country’s industrial sector (including the chemical industry) will rely excessively on coal resources. For example, both the composition of the raw material routes used in ammonia synthesis production in our country and the rapid development of the calcium carbide industry are closely tied to the unique resource conditions in our country. During the use of coal resources, there are problems of severe pollution and low energy utilization efficiency, which inevitably have a significant impact on the energy consumption of products. 　　Currently, the proportion of domestic and international energy consumption (expressed in terms of standard coal) is as follows: in China, about 70% comes from coal, while abroad it is less than 30%. In China, oil and natural gas account for less than 30%, whereas abroad this figure is above 60%. The proportion of other forms of energy is relatively similar in both regions. 　　2. Raw material route The raw material route in the chemical industry has a significant impact on the energy consumption of products. In this regard, there are significant differences between domestic and international situations. For example, in the ammonia synthesis industry, over 70% of ammonia produced in China is manufactured using coke as a raw material, while 20% uses natural gas. Worldwide, however, 80–90% of ammonia is produced from natural gas; in the United States, this figure even reaches 98%. Since coal-based ammonia synthesis requires 60% more energy per unit of output compared to natural gas-based methods, this results in China’s energy consumption per unit of ammonia produced being significantly higher than the international average. 　　3. Enterprise scale 　In the chemical industry, the main energy-intensive products are bulk commodities; in developed countries, enterprises are generally large in scale, which facilitates the rational use of energy and improves the efficiency of equipment utilization. In our country, there are many small and medium-sized enterprises, with an average production scale that is relatively small, which is a significant difference compared to developed countries. For example, the average annual production capacity per ammonia synthesis plant in China is less than 100,000 tons, while it is generally 300,000 tons per plant abroad ； The average annual production capacity per calcium carbide plant in China is less than 50,000 tons, while it is 220,000 tons in Japan, 170,000 tons in the United States, and 200,000 tons in Germany. This disparity in enterprise size is an important reason for the relatively high energy consumption of major energy-intensive products in the domestic chemical industry. For example, the average energy consumption per unit of product in large ammonia synthesis plants is 1,490 kilograms of standard coal per ton, while the average for medium-sized plants is 1,792 kilograms of standard coal per ton; the average for small plants is 1,811 kilograms of standard coal per ton. The average comprehensive electricity consumption of small and medium-sized calcium carbide manufacturers in China is around 3650 kWh per ton, while that of large-scale closed-type electric furnace manufacturers is about 3200 kWh per ton, which is roughly on par with foreign levels. 　　4. Equipment Level The design, material quality, manufacturing standards, and operational control of equipment used in chemical production processes as well as general-purpose equipment have a decisive impact on the energy consumption of products. For example, in China, the equipment and processes used for ammonia synthesis have seen a coexistence of outdated and advanced methods over different periods; the overall level of equipment is low, which results in high energy consumption. In contrast, developed foreign companies integrate various production units into a single system to make efficient use of energy, employing a hierarchical approach to energy utilization (heat and power integration) and reusing energy sources to maximize the efficiency of energy use, thereby reducing energy consumption per ton of ammonia to the lowest possible level. Another example is the production of caustic soda by the diaphragm method: in China, various technical systems coexist, including those developed independently, those based on imported technologies that have been localized, as well as those utilizing advanced foreign technologies. Some of these systems are advanced while others are outdated, which results in a low overall energy efficiency level. In contrast, abroad, the focus is mainly on expanding the anodes and using modified diaphragm processes and equipment, leading to a higher overall energy efficiency level. 　　5. Policy factors 　**Policy guidance is an important force in improving the energy efficiency of products.** In recent years, although **several policies and measures to encourage energy conservation have been introduced, certain results have been achieved. However, some policies still need further improvement and implementation, such as incentive and restraint measures in areas like investment, finance, and taxation, the establishment of mandatory energy efficiency standards for high-energy-consuming products, and market entry and exit mechanisms that complement project development. At the same time, further coordination is also needed between the central and local governments regarding the sharing of benefits and costs. These unfavorable conditions pose obstacles to accelerating the adoption of advanced energy-saving technologies. 　　6. Other factors Operational load factor: In some ammonia synthesis plants, insufficient supply of raw materials such as natural gas and coal leads to a decrease in operational load, causing the operation to deviate from the optimal range specified in the equipment design. This results in increased energy consumption by the plants, and consequently an increase in energy consumption per unit of product produced. Ammonia synthesis plants that use natural gas as a raw material are greatly affected by this factor. Raw material quality factors: The raw materials supplied by some ammonia synthesis plants are of poor quality, unstable, and have a high ash content, which leads to a decline in the quality of the gas produced and an increase in energy consumption. In some calcium carbide plants, the fixed carbon content of the raw material coal is below the required level, and the calcium content of the limestone does not meet the specified standards; these factors all lead to increased energy consumption in the production process. 　　Statistical method factor: For the statistics on energy consumption of chemical products, foreign data usually refer to the values determined during process design, while domestic statistics include the share associated with auxiliary and supporting processes. In other words, there is a difference in the scope of these statistics; the domestic scope is broader than that used abroad, which is why the energy consumption values for domestic products are higher. 　　IV. Measures and Recommendations to Improve Energy Efficiency in the Chemical Industry (I) Difficulties and Problems in Improving the Energy Efficiency of High-Energy-Consuming Chemical Products 1. Lack of mandatory policy measures to improve the energy efficiency of this industry To enhance the energy efficiency of this industry, it is necessary to control the \"increment\", that is, to strictly restrict the initiation of projects with low energy efficiency ； On the other hand, there is the transformation of existing assets, that is, increasing efforts to improve the energy efficiency of current low-efficiency equipment (systems). Mandatory measures are required in both of these areas to ensure effective implementation. However, such means are currently lacking. Regarding the former, the lack of effective enforcement measures has resulted in limited success in raising the starting point for the energy efficiency level of new projects. Regarding the latter, the lack of a basis for mandating the phasing out of energy-intensive and inefficient equipment, coupled with insufficient investment by industry companies in energy-saving upgrades, has resulted in the existing energy-intensive and inefficient production processes and equipment not being fundamentally restricted or eliminated. In short, the lack of mandatory measures to improve the energy efficiency of this industry is one of the biggest challenges in efforts to save energy in energy-intensive chemical sectors. Whether this issue can be resolved promptly will directly determine whether energy-saving efforts can be carried out effectively. 　　2. Insufficient efforts have been made in the development and promotion of energy-saving and emission-reduction technologies. Advancing energy conservation and emission reduction efforts requires technical support. Over the years, companies have invested heavily in expanding their scale, but insufficiently in research and development of technologies for energy conservation and emission reduction. Even though some companies have developed effective energy-saving and emission-reduction technologies, for their own interests, some are reluctant to share them with the industry. Therefore, how to accelerate the development of energy-saving and emission-reduction technologies, as well as select and integrate such technologies across the industry, is an urgent issue that needs to be addressed. Furthermore, for industries that already possess mature sets of energy-saving and emission-reduction technologies, **the efforts to promote these technologies and provide specific support are insufficient. 　　3. Inadequate energy conservation management structures in enterprises At present, although the industry attaches great importance to energy conservation efforts, the lack of appropriate organizational structures and personnel means that many enterprises do not have dedicated energy conservation management teams, or such teams are not equipped to meet the demands of enhanced energy conservation initiatives. A considerable number of key energy-consuming enterprises lack full-time staff responsible for energy conservation, which results in energy consumption and conservation practices remaining largely informal. As a result, energy conservation policies cannot be effectively implemented within these enterprises. People describe energy-saving efforts as: “Important in theory, less important in practice, and ignored when things get busy.” This situation must be reversed as soon as possible; there can be no talk of energy conservation without dedicated staff for it. 　　4. The implementation of energy-saving measures in enterprises lacks financial and policy support. At present, with high energy prices, large energy consumers in the industry are highly motivated to adopt energy-saving practices. However, for various reasons, on the one hand, companies do not have sufficient funds to support energy-saving efforts, such as the development and application of energy-saving technologies ； On the other hand, some energy-saving projects in enterprises lack policy support, which prevents them from being implemented or prevents them from functioning effectively once completed. 　　5. The basic work related to energy statistics and energy conservation management is seriously lagging behind. 　　Currently, the methods for tracking energy consumption in this industry are quite inadequate. Some were established over a decade ago and are no longer suitable for the current needs of the industry ； For some, there are no standards at all, and it is necessary to research and establish them immediately. The formulation or revision of energy-saving design specifications and energy efficiency standards for high-energy-consuming products is also significantly lagging behind or lacks essential elements, making it difficult to provide effective support for controlling the energy efficiency of new industrial production capacity. Existing statistical data hardly reflect the actual situation of the industry, and much hard work is still required to establish and improve the statistical, standard, and regulatory systems for energy conservation and emission reduction. Furthermore, the workforce responsible for statistics and management related to energy conservation and emission reduction is very weak, and many enterprises do not have dedicated energy managers ； At the same time, since the chemical industry operates on a continuous production basis, it is not possible for companies to conduct monthly and quarterly statistics; even the energy consumption over half a year is estimated. Therefore, it is quite difficult to carry out monthly and quarterly tracking analysis and research. 　　(II) Recommendations for relevant measures 1. Strengthen the market access system and enhance the guidance provided by industrial policies. During the 11th Five-Year Plan period, due to the economic development of the industry and the need to upgrade existing outdated production facilities, there will be varying degrees of expansion in new production capacity ； Establishing a market access system helps to control the scale of new production capacity in the chemical industry and to enforce strict energy efficiency standards. It is an effective way to promote technological progress in this sector, as well as an important guarantee for achieving energy conservation and emission reduction goals. However, at present, only a few industries such as chlor-alkali and calcium carbide have established market access systems, while market access systems for most energy-intensive products have not yet been put in place. Therefore, it is necessary to establish an industry market access system as soon as possible and strengthen policy guidance for industrial development. 　　2. It is recommended to **formulate policies for phasing out outdated production capacity and establish a mechanism for such phasing out. At present, industries such as calcium carbide and yellow phosphorus are developing too rapidly, resulting in excessive production capacity; some of these enterprises have high energy consumption levels and low levels of comprehensive utilization. According to industrial policies, they should be phased out, but the lack of an appropriate mechanism makes it quite difficult for local authorities to shut down these enterprises. Adjusting the structure and phasing out outdated production capacity are important means of achieving energy-saving goals in the industry, but eliminating such outdated capacity involves various factors such as the local economy and employment; **without an appropriate exit mechanism, it is very difficult to do so. Therefore, it is recommended to **introduce policies for phasing out outdated production capacity as soon as possible**. 　　3. Increase the promotion of key practical energy-saving and emission-reduction technologies. 　　The upgrading of technical equipment plays a decisive role in further reducing energy consumption. Certain technologies that are crucial for promoting energy savings and reduction in this industry, although they have already seen some demonstration-based industrial applications in the country, have not been widely adopted enough; greater efforts should be made to promote their use in the future. 　　4. Strengthen the control of factors affecting energy consumption, such as production operation load, operations, and raw material quality. 　　The energy efficiency benchmarking initiative currently being carried out across the country is a good approach. It can help enterprises strengthen energy management, assisting them in improving energy efficiency across various aspects such as raw material quality, operational control, and rational planning. 　　5. Strengthen in-depth research on international comparisons of product energy consumption. 　　The industrial sector accounts for nearly 70% of China’s total final energy consumption, making it a key focus for energy conservation efforts. International comparison of product energy consumption is an important aspect in formulating energy-saving policies and plans. It is recommended that the relevant authorities assign a soft science project to conduct in-depth systematic research and quantitative analysis. 　　6. Industry associations should play an important role in carrying out benchmarking activities. 　　**At the State Council’s meeting on energy conservation and emission reduction, the Prime Minister called for the implementation of benchmarking activities; **the National Development and Reform Commission also formulated an Implementation Plan for Benchmarking the Energy Efficiency Levels of Key Energy-Consuming Enterprises**. We believe that associations should play an important role in carrying out energy efficiency benchmarking activities in key energy-consuming industries. 　　The association can establish benchmark indicator systems and statistical criteria, as well as determine the principles for selecting benchmark values and for enterprises to submit basic data ； Establish a data platform for benchmarking energy efficiency levels, to collect information on advanced process technologies, equipment capacity, and energy efficiency standards both domestically and internationally, as well as on best practices for energy savings, by industry ； Recommend or select benchmarks or model companies for comparative activities ； Provide consulting services to the energy conservation authorities in various provinces (regions, municipalities), and offer guidance and information support for enterprises carrying out benchmarking activities ； Establish energy efficiency standards for industry-related products, and carry out activities to certify energy-saving labels. 　　Energy conservation is now regarded as a \"fifth energy source\" as important as coal, oil, natural gas, and electricity. The path the chemical industry must follow is to pursue energy savings and reduced consumption to the fullest extent possible.