Thread Content
In 2007, the ethylene production units of Sinopec Group Corporation (hereinafter referred to as Sinopec), in accordance with the unified directives from the headquarters, faced rising raw material costs and increasing fluctuations in product prices. They adhered to a market-oriented approach with the goal of improving overall efficiency, focused on ensuring safe production, strengthening refined management, optimizing production organization, and carrying out technical innovations. They also implemented various measures aimed at saving energy and reducing consumption, as well as ensuring long-term operational stability. By doing so, they managed to increase the operational rate, utilization rate, and reliability of their facilities, exceeding their annual targets and making significant contributions to improving Sinopec’s overall production and operational standards. 1 Performance of key indicators in 2007 1.1 Ethylene production capacity As of the end of 2007, Sinopec had 11 ethylene production facilities (including Sinopec Shanghai Petrochemical and Yangzi Petrochemical), with a total of 12 ethylene plants. The overall ethylene production capacity was 6,295 kt/year; no new production capacity was added during that year. This represented 63% of China’s total ethylene production capacity of 9,985 kt/year (according to statistics from the National Ethylene Industry Association). 1.2 Ethylene production: In 2007, Sinopec produced 6,693.9 kt of ethylene in total (including the capacity of Sinopec’s Caihua and Yangzi Petrochemical plants), an increase of 363.0 kt compared to the previous year, representing a growth rate of 5.7%. This amount accounted for 65% of China’s total ethylene production of 10,277.8 kt (according to statistics from the National Ethylene Industry Association). Yanshan Ethylene underwent a major overhaul between March and April, during which the system was thoroughly serviced; in December, the leak in the small cold box was fixed through a temporary shutdown taken advantage of the reduced production volume. In light of the significant changes in the structure and quality of the cracking feedstock following the refinery renovation, the production plan was optimized, resulting in 748.5 kt of ethylene produced throughout the year, a decrease of 71.5 kt compared to the previous year. Despite the challenges posed by outdated equipment and an increasing number of equipment issues, Shanghai No. 1 Ethylene Plant managed to operate steadily throughout the year, with only one shutdown in October due to a burst in the seawater pipeline. It produced 158.4 kt of ethylene, a decrease of 9.7 kt compared to the previous year ； Shanghai No. 2 Ethylene plant underwent major repairs in July and August; it produced 711.0 kt of ethylene throughout the year, a decrease of 81.2 kt compared to the previous year. Qilu Ethylene made great efforts to overcome various adverse factors, resolving issues such as high shaft vibration in the intermediate-pressure cylinder of the small-line pyrolysis gas compressor, liquid flooding in the high- and low-pressure depropanization towers, and poor injection of dilution steam into the pyrolysis furnace. Through careful production management and the thorough exploitation of the plant’s potential, it produced 846.8 kt of ethylene throughout the year, an increase of 8.0 kt compared to the previous year; production levels reached record highs for three consecutive years. Overcoming difficulties such as numerous issues with the auxiliary boiler equipment, operational pressures, and an increase in pressure differences in the gasoline fractionation tower of the Yangzi Ethylene plant, the facility managed to operate at a high load level throughout the year. A total of 801.1 kt of ethylene was produced, representing an increase of 46.1 kt compared to the previous year; thus, ethylene production exceeded the 800-kt mark once again, following the achievement in 2004. On the one hand, Maoming Ethylene overcame various challenges such as frequent problems with the cracking gas compressors in the old production line, numerous issues with the downstream equipment, and difficulties in maintaining an optimal balance of ethylene production. On the other hand, it strengthened the commissioning and adjustment processes after the new line went into operation, resolving a series of problems including high viscosity of the quench oil, excessive CO2 levels at the top of the alkaline scrubber tower, and leaks in the cold boxes. Together, the two production lines generated 962.6 kt of ethylene throughout the year, representing an increase of 440.4 kt compared to the previous year. Guangzhou Ethylene completed its cross-year maintenance in mid-January; after the plant was restarted, it operated steadily, producing 210.7 kt of ethylene throughout the year, an increase of 15.0 kt compared to the previous year. Tianjin Ethylene underwent scheduled maintenance in February and March, addressing issues such as high shaft vibration in the cracking gas compressor and fouling and blockage of the trays in the condensate stripping tower. Throughout the year, 225.5 kg of ethylene was produced, a decrease of 6.1 kt compared to the previous year. Zhongyuan Ethylene took effective measures to increase the use of light hydrocarbons; the plant underwent a short shutdown for maintenance at the beginning of July, and produced 211.5 kt of ethylene throughout the year, a decrease of 3.0 kt compared to the previous year. Affected by the production cuts at downstream PVC plants, the ethylene plant at Dongfang Ethylene operated at 80%-90% capacity after April; overall, 160.1 kt of ethylene was produced that year, a decrease of 8.2 kt compared to the previous year. Sinopec Ethylene made efforts to address the issues associated with short operation cycles and frequent switching of the cracking furnaces, as well as the negative effects resulting from long-term operation of the plant. It produced 1,002.9 kt of ethylene throughout the year, an increase of 25.0 kt compared to the previous year; this made it the first plant in China to achieve an annual ethylene production volume of over one million tons. Moreover, since the plant was first put into operation in March 2005, it has not required any maintenance to date. Yangba Ethylene actively addressed the challenges posed by frequent instrument failures in the pyrolysis gas compressors, and resolved issues such as methane pipeline leaks. Since its first operation in May 2005, it has not required any maintenance, producing 654.8 kt of ethylene throughout the year, which represents an increase of 8.2 kt compared to the previous year. 1.3 Ethylene and diolefin yields: In 2007, Sinopec’s ethylene yield was 30.78% (excluding Sinopec Caojing and Yangzi Petrochemical), an increase of 0.23 percentage points compared to the previous year. Looking at individual plants, the highest ethylene yield was achieved by Zhongyuan Ethylene at 34.66%, followed by Guangzhou Ethylene at 34.12% ； The lowest is Shanghai No. 1 ethylene at 29.62%, followed by Shanghai No. 2 ethylene at 29.97% ； Except for Shanghai Ethylene No. 2, the ethylene yield of the other 9 units all increased on a year-on-year basis; the greatest increase was seen in Guangzhou Ethylene, with an increase of 2.62 percentage points ； The ethylene yield of the 4 plants in Guangzhou, Tianjin, Zhongyuan, and Qilu all reached record-high levels. In 2007, Sinopec’s diolefin yield was 45.43% (excluding Sinopec Caozhou and Yangzi Petrochemical), an increase of 0.35 percentage points compared to the previous year, reaching the highest level on record. Looking at individual units, the highest yield of dienes was achieved by Guangzhou Ethylene at 49.28%, followed by Tianjin Ethylene at 48.57% ； The lowest is Shanghai No. 2 Ethylene at 43.53%, followed by Qilu Ethylene at 44.72% ； Except for Shanghai Ethylene Units 1 and 2, the yield of diolefins in the remaining 8 units all increased on a year-on-year basis; the greatest increase was observed in Guangzhou Ethylene, with an increase of 3.28 percentage points ； The diolefin yields of the 3 units in Guangzhou, Tianjin, and Zhongyuan all reached record-high levels. 1.4 Energy consumption per ton of ethylene produced: In 2007, the energy consumption per ton of ethylene produced at Sinopec’s plants (expressed in terms of standard oil) was 670.61 kg/t (excluding the SPC and Yangzi Petrochemical plants), representing a decrease of 5.94 units compared to the previous year, and this marked the lowest level ever recorded. Looking at individual units, the lowest energy consumption (in standard oil terms) is recorded by Tianjin Ethylene at 614.01 kg/t, followed by Maoming Ethylene at 622.92 kg/t ； The highest value was for Shanghai Ethylene No. 1 at 840.50 kg/t, followed by Shanghai Ethylene No. 2 at 739.67 kg/t. Except for Shanghai No. 2 and Qilu Ethylene, the ethylene energy consumption of the remaining 8 plants all decreased to varying degrees; the largest reductions were observed in Maoming, Yanshan, and Guangzhou Ethylene, with decreases of 33.02, 24.76, and 18.96 units respectively ； The ethylene energy consumption of the five units in Yanshan, Yangtze, Guangzhou, Tianjin, and Dongfang all reached record lows. 1.5 Plant loss rate: In 2007, the loss rate for ethylene plants in Sinopec was 0.58% (excluding Sinopec Caiyang and Yangzi Petrochemical), a decrease of 0.09 percentage points compared to the previous year. Looking at individual plants, the lowest loss rate is 0.37% for Maoming Ethylene, followed by Yangzi Ethylene at 0.38% ； The highest is Dongfang Ethylene at 1.59%, followed by Shanghai No. 2 Ethylene at 1.15% ； Except for Shanghai Unit 1 and Unit 2 as well as Zhongyuan Ethylene, the loss rates of the remaining 7 units all decreased on a year-on-year basis; the largest drops were observed in Dongfang, Maoming, and Yanshan, with decreases of 2.15, 0.40, and 0.15 percentage points respectively ； The loss rates of the 5 units in Yanshan, Yangtze, Guangzhou, Tianjin, and Dongfang all reached their best levels on record. 2 Main tasks and achievements in 2007 2.1 Raw material optimization To fully leverage the advantages of integrated upstream, midstream, and downstream operations and to improve resource utilization efficiency as well as overall profitability, Sinopec’s headquarters organized a special competition in the second half of 2007 aimed at increasing the yield of \"dienes\". Each ethylene producer ensured the implementation of goals, organizational structures, systems, and relevant measures; as a result, the yield of diolefins in the second half of the year was 0.34 percentage points higher than the average level for January to May, achieving good results. The Yanshan branch in Beijing completed the reform of its refinery with a capacity of 10,000 kt/a in June. The ethylene plant stopped using HGO in July, resulting in significant improvements in the structure and quality of the feedstock used for cracking. Efforts were also made to ensure the stable operation of the unit that recovers ethylene from catalytic dry gas. By making full use of the propane available in the refinery, two additional gas furnaces were put into operation at the same time. In the second half of the year, the yield of dienes reached 45.42%, an increase of 1.38 percentage points compared to the first half of the year. On the one hand, Shanghai Petrochemical makes full use of the excess capacity for LPG production from ethylene cracking unit No. 2, by tapping into internal sources of light hydrocarbons used in refining; 14.4 kt of such light hydrocarbons were utilized in the fourth quarter ； On the other hand, the cracking performance of naphtha and hydrocracking tail oil is ensured by adjusting the naphtha fraction cut point and feeding paraffin-based VGO into medium-pressure hydrocracking, among other methods. In the second half of the year, the quality of the naphtha produced by the Qilu branch improved, with the average alkane content increasing by 1.4 percentage points. The quality of naphtha purchased from external suppliers was even better than that of the naphtha produced internally. Meanwhile, the \"separate storage and processing\" measures were further refined; by working in collaboration with research institutions, evaluations of the properties of the cracking feedstock were carried out, and the outlet temperature of the cracking furnaces was adjusted promptly to maintain an optimal level of cracking depth. Yangzi Petrochemical purchases some paraffin-based crude oil to improve the quality of its own naphtha production ； By adjusting the output profiles of the two hydrocracking units, the components of the hydrocracking tail oil were further optimized ； Using propane and liquefied gas from refineries and aromatic plants as cracking feedstocks adds another means for optimizing raw materials. The Maoming branch has done a lot of work in optimizing raw materials: first, it has increased the proportion of sand-light and paraffin-based crude oils purchased, which are suitable as raw materials for pyrolysis ； Secondly, the dry point of the domestically produced naphtha was appropriately reduced, improving the quality of the naphtha ； Third, efforts have been made to develop light hydrocarbon resources; not only has the amount of light hydrocarbons produced internally by the refinery been increased from 11 kt per month to 15 kt, but it has also become possible to receive light hydrocarbon resources from other refineries in the region by improving the facilities for receiving such hydrocarbons ； Fourth, strictly control the yield of hydrocracking tail oil to ensure its quality ； Fifth, strict quality control is applied to purchased raw materials entering the factory, with continuous efforts to improve the quality of naphtha supplied to each other ； Sixth, a plan for the \"separate storage and division\" of pyrolysis feedstocks was implemented starting in August. Through these measures, the annual diolefin yield reached 45.79%, ranking first among the 5 large integrated refining and chemical companies. After the Guangzhou branch completed the expansion and renovation of its refinery with a capacity of 12,000 kt/a by the end of 2006, the quality of the feedstock used for cracking improved significantly in 2007; there was an increase in the use of tail oil, C5 compounds, and light naphtha. As a result of these improvements, it became possible to use light naphtha for cracking in two separate reactors. In 2007, the yield of dienes reached 49.28%, representing a significant increase of 3.28 percentage points compared to the previous year. The Tianjin branch optimized the types of crude oil processed and adjusted the cut ranges for light and heavy naphtha, enabling the normal alkane content in light naphtha to reach over 35%; at the same time, it increased the supply of propane from the refinery for use as raw material in ethylene cracking ； Testing the simultaneous use of hydrocracking tail oil in two pyrolysis units was successful; the viscosity of the quench oil remained within acceptable levels, and the daily yield of dienes increased by approximately 1 percentage point compared to when hydrocracking tail oil was used in a single unit. Zhongyuan Petrochemical took measures to increase the use of light hydrocarbon resources; in 2007, light hydrocarbons accounted for 14.5% of the raw materials used, and the ethylene yield reached 34.66%, an increase of 0.80 percentage points compared to the previous year. On the one hand, Dongfang Petrochemical strictly controls the average alkane content in naphtha to be above 70%, and implements a \"separate storage\" strategy based on the density of the naphtha and its alkane content ； On the other hand, by making full use of the domestically produced C5 by-products, n-pentane and isopentane remaining after the extraction of cyclopentane were reused as feedstock for cracking, thereby increasing the yield of dienes. 2.2 Operational Optimization Based on the actual application of advanced control technologies in Yangzi and Qilu ethylene plants, Sinopec’s headquarters worked with various companies to promote the use of these technologies, and a plan for the first phase of implementation was established. This phase focuses on load control for cracking furnaces and control of COT deviations, as well as distillation control in the ethylene and propylene distillation towers. At present, Shanghai Plant 2 has completed the development and debugging of advanced control systems for 4 SL-Ⅱ type cracking units and 3 GK-Ⅵ type cracking units. The development of advanced control systems for the ethylene distillation tower and the propylene distillation tower has been finished, and they are currently in the stage of on-site debugging ； The advanced control systems for the ethylene distillation tower and propylene distillation tower at Guangzhou Ethylene have been put into operation and are currently in the evaluation phase. Taking advantage of the shutdown for maintenance in April, Yanshan Ethylene completed the installation of all models for the butane APC system. All APC controllers are now in use, and the fluctuations in the key control parameters have been reduced, essentially meeting the design objectives; as a result, the economic efficiency of the plant’s operation has improved ； In conjunction with the operation of the APC system, it is necessary to carefully monitor and analyze the quality of raw materials, use the SPYRO software to optimize operating conditions, and adjust the COT according to different oil types and the operating status of the cracking furnace, in order to maximize the yield of dienes. At the end of October, Qilu Ethylene organized an online speed increase for the pyrolysis gas compressor; the compressor’s rotation speed was increased by 200 r/min, and the inlet pressure decreased by 15 kPa under the same load. Yangzi Ethylene makes full use of the advantages of its two production lines. By leveraging the high selectivity and large output per furnace of the new line’s cracking furnaces, it allocates the operating load between the old and new lines in an efficient manner, resulting in the four furnaces on the new line being in operation for 118 more days compared to the previous year ； On the other hand, technical efforts were made to address this issue; in March, the configuration of the cracking gas compressors on both the new and old lines was changed from inlet series connection to outlet series connection. As a result, the suction pressure of the cracking gas compressors on both lines decreased by 10 kPa, which in turn reduced the pressure at the exit of the cracking furnace and created favorable conditions for increasing the yield of ethylene. Maoming Ethylene implemented advanced control on 3 new cracking units that met the requirements, which simplified operations; the COT deviation for each unit was reduced from 3°C to 1°C, while the overall COT fluctuation dropped from 3–4°C to within 2°C ； In August, sampling and calibration were carried out on the pyrolysis depth of all pyrolyzers, and the propylene/ethylene ratio was adjusted based on the results of raw material evaluation, in order to maximize the yield of dienes as much as possible ； After eliminating the leakage points in the cold box of the new ethylene line and the triple-effect refrigerant cooler, the refrigerant composition was adjusted and stabilized, keeping the ethylene loss at the top of the demethanization tower within normal limits. Under the overall material balance conditions at Tianjin Ethylene, through analysis and optimization, an optimal raw material ratio for the 6 cracking units when operating at full capacity was determined, enabling a daily ethylene production volume of 660 tons. 2.3 Energy conservation and emission reduction: Under the unified organization of Sinopec’s headquarters, energy-saving upgrades to air preheaters for the cracking furnaces in certain units were carried out in 2007. By the end of 2007, a total of 60 pyrolysis furnaces had been upgraded and put into operation. Depending on the medium used, the air temperature rise ranges from 50 to 100°C, resulting in a 1.5%-3.0% reduction in the total fuel consumption of the pyrolysis furnace. Through carrying out heating furnace competition activities, Yanshan Ethylene has currently managed to keep the thermal efficiency of its cracking furnaces at around 93%, which is close to the design value ； Drawing on the experience of Qilu Ethylene, a specific \"Ethylene and Propylene Recovery Plan\" was developed prior to the major maintenance; this plan enabled the recovery of 177 tons of ethylene and 260 tons of propylene without affecting the progress of the plant shutdown and emptying process ； A trap management ledger was established to enhance the monitoring and management of traps, ensuring that damaged traps are addressed or replaced promptly. Maoming Ethylene has extended the operating cycle of its cracking furnaces by updating the material used for the furnace tubes and by carefully planning the coking schedule for these furnaces; as a result, the older cracking furnaces are now in a \"cold standby\" state, saving approximately 230 tons of fuel gas per month ； The insulation materials in the furnaces of 8 pyrolysis units were replaced one by one, reducing the heat loss from those furnaces. To address the issue of burning off excess fuel gas, Dongfang Ethylene decided to recover the flare gas for use in coal gas blending projects. On December, the joint commissioning of a project to use flare gas in two 75t/h fluidized bed boilers was successful; 1700 m3/h of excess flare gas (under standard conditions) from the ethylene plant was recovered, effectively reducing material losses in the plant. Taking advantage of the shutdown caused by a pipe rupture in the seawater pipeline on October 18, Shanghai No. 1 Ethylene carried out repairs on the leaking E-314 and E-329 heat exchangers. After starting operation, the daily propylene production increased from 210 t before the issue was resolved to around 230 t, reducing propylene losses by about 20 t per day. Zhongyuan Ethylene focused its efforts on replacing nearly 2,000 traps in the facilities, implemented a condensate reuse program, cleared the condensate pipelines, and increased condensate recovery, thereby fundamentally reducing leaks at the site. 2.4 Technical Solutions: In the ethylene recovery unit of the Yanshan Ethylene plant, the overhead gas from the demethanization tower in the pre-distillation section contains about 40% ethylene. Due to concerns regarding the potential risks posed by trace amounts of NOx, this overhead gas has been discharged into the fuel system, resulting in losses of ethylene. By collaborating with research institutions to develop methods for NOx analysis, it was confirmed that the risk associated with NOx was within acceptable levels. Starting in July, this non-condensable gas was introduced into the facility, allowing for the recovery of approximately 1,500 tons of ethylene per year; this experience also provides a reference for the widespread adoption of dry gas recovery technologies in refineries. Through the implementation of contracted management for the cracking furnaces, Qilu Ethylene has increased the average annual operating cycle of these furnaces by about 10 days compared to 2006, achieving significant progress in this area ； Efforts were made to improve the processing capacity of the high and low pressure depropanization towers as well as the quality of the butane products. Inspections revealed that the low pressure depropanization tower had issues such as liquid flooding in its upper section and the detachment of 3 trays in its lower part; after adding an additional feed line, the quality rate of the butane products increased significantly. In response to the issue of excessive CO2 levels in its ethylene products over a period of time, Zhongyuan Ethylene established a task force to address this problem. By analyzing the causes and adjusting the operating procedures, the quality of the ethylene product was maintained. Furthermore, through strict control of the operation of the DA-151/152 towers and the optimization of related systems, it was possible to reduce the amount of alkali used from 1200 kg/h to 500–600 kg/h, while still ensuring that the acidic components at the top of the alkaline scrubbing tower did not exceed acceptable levels. In response to the problems that arose after the new production line at Maoming Ethylene came online, targeted technical efforts were undertaken, and significant results were achieved through the joint efforts of all relevant parties. In June, a performance assessment was conducted on the separation system, and in August, a performance assessment was carried out on the two SL-I type pyrolyzers. The key performance indicators met the target values; going forward, efforts will continue to address any remaining issues. 2.5 Technical Upgrades and Improvements: During its major overhaul, Yanshan Ethylene replaced the furnace tubes of the BA-110/111 gas furnaces with new tubes equipped with twist plates; it also addressed issues such as the poor weldability of the furnace tubes, broken outlet lugs, and short operational cycles ； Through technical upgrades, an additional propylene recovery tower, DA-1406, was added. After it came online in August, the propylene content in the liquefied gas product dropped from 19% to less than 2%, resulting in an increase of about 30 tons of propylene produced per day. Taking advantage of the shutdown for maintenance in July, Shanghai No. 2 Ethylene upgraded 7 SRT-III type furnaces, increasing the capacity of 3 of these furnaces from 45 kt/a to 60 kt/a. For the remaining 4 boilers, only the convection section was replaced and the corresponding piping was adjusted, with an addition of an ultra-high pressure steam superheating section ； Taking advantage of the opportunity to replace the furnace tubes in the BA-2102 cracking furnace, twisted tube inserts were installed. Taking the opportunity of replacing the furnace tubes in its BA-101 cracking furnace, Qilu Ethylene carried out appropriate modifications to the furnace: the diameter of the tubes in the radiation section was increased, twist plates were installed, the design of the bottom elbows was improved, and all the top suspension springs were replaced to minimize tube bending. After the modification, the time required to feed oil and shut down the pyrolyzer was significantly reduced, from 2 hours to 0.5 hours, simultaneously addressing the issue of short operation cycles for this furnace. From the perspective of regional optimization and maximizing overall corporate efficiency, Guangzhou Ethylene carried out adaptive modifications to the hydrocracking tail oil treatment unit, enabling Unit B to process cracking tail oil; this helps to extract some naphtha for local supply to Maoming Ethylene. In June, Tianjin Ethylene replaced the furnace tubes in conjunction with the BA-104 cracking furnace and added twist plates to them. After coming online, the upward trend in the surface temperature of the furnace tubes slowed down significantly compared to before; the first operating cycle lasted 115 days, which is nearly double the previous duration ； Twist plates were also installed during the replacement of the furnace tubes in the BA-106 pyrolyzer in October, and good results were achieved after it was put into operation. In March, Zhongyuan Ethylene carried out an expansion upgrade of the BA-102 cracking furnace, increasing its capacity from 35 kt/a to 50 kt/a; twist plates were also installed on the furnace tubes, which played an important role in enabling the plant to operate at high loads. In April, an online technical upgrade was carried out on the propylene refrigeration system, with the new heat exchanger EA-501CN put into use. The outlet pressure of the propylene refrigeration compressor dropped from 1.8 MPa to 1.47 MPa, and the plant’s operating load increased by nearly 10%, effectively eliminating the \"bottleneck\" that restricted high-load operation of the plant during the summer. To address the issue of the extremely high pressure of steam generated by the cracking furnace, which deviated significantly from the design parameters and affected turbine efficiency, Dongfang Ethylene commissioned a design firm to carry out experimental modifications on Cracking Furnace No. 5. On December 5, on-site construction began, and the system was put into operation on the 28th of the same month. The temperature of the ultra-high pressure steam reached the designed level of 515°C; in addition, twist plates were installed on the furnace tubes as part of the tube replacement process. In addition, Dongfang Ethylene has also completed the variable-frequency transformation of the fans for 5 cracking units and put them into operation. 2.6 Long-term operation and maintenance: While continuing to pursue the goal of maintenance every four years, maintenance plans for various units are arranged in a coordinated manner based on the overall situation of Sinopec and the actual conditions of each enterprise; some units undergo opportunistic maintenance or short-term shutdowns to address defects. Since its expansion and renovation were completed and it came online in October 2004, Qilu Ethylene had been in operation for 38 months by the end of 2007. In 2007, to address the issue of excessive vibration in the intermediate-pressure cylinder of the pyrolysis gas compressor, measures such as adding polymerization inhibitors and scale removers to the oil used for cleaning were taken; as a result, shaft vibration was reduced from a maximum of 38 μm to 20 μm, ensuring the long-term operation of the unit. Yanshan Ethylene underwent scheduled shutdown for major maintenance on March 25; this operation cycle followed the \"every four years\" maintenance schedule (44 months of operation), and it resumed production on April 23. During the maintenance period, in addition to carrying out routine overhauls, 21 measures aimed at ensuring long-term operation were implemented, effectively eliminating the \"bottlenecks\" that hindered such operation. The old and new ethylene plants in Shanghai were shut down for maintenance as scheduled on July 10 and 12 respectively. During this cycle, the old plant underwent a major repair every five years (after 60 months of operation; it had undergone a minor repair in 2004), while the new plant also had a repair every five years (after 63 months of operation). The old line resumed feeding on August 10, and the new line resumed feeding on August 20. The old Maoming ethylene plant was shut down for maintenance as scheduled on October 8, with focus being given to addressing the issue of high vibration in the turbine shaft of the cracking gas compressor; operations were resumed on the 20th ； On December 24, the new line was shut down for maintenance due to a leak in the cold box; during this time, issues such as blockage of the large valve for pyrolysis gas, insufficient capacity of the quench oil nozzles in the viscosity reduction tower, detachment of internal components in the alkali washing tower, and leaks in the three-way refrigerant cooler were addressed. The cold box was heated and dried, and operations were resumed on January 5, 2008. On February 26, Tianjin Ethylene took advantage of the interlock shutdown of the pyrolysis gas compressor to carry out routine maintenance on the plant, addressing issues such as scaling and blockage in the condensate stripping tower as well as high shaft vibration in the pyrolysis gas compressor; operations were resumed on March 6. Zhongyuan Ethylene carried out a short shutdown for maintenance from July 3 to 6, during which cooling water heat exchangers such as EA-130, EA-501A/B, and EA-502 were cleaned. This addressed the issue of insufficient capacity in the cooling equipment that affected high-load operation during the summer. Meanwhile, the cause of the high shaft vibration in the pyrolysis gas compressor over the past two years was identified and resolved. 2.7 Progress of new projects: Currently, Sinopec has 4 ethylene projects under construction, with a total ethylene production capacity of 3600 kt/a. The detailed design for Fujian’s 800kt/a ethylene project has been largely completed. The domestic dynamic and static equipment is now in the critical phase of manufacturing supervision, inspection, and acceleration of delivery. The steel structure of the cracking furnace has been installed, and large-scale units such as the propylene distillation tower, demethanization tower, and alkali scrubbing tower have been fully erected. The entire project is progressing as planned, with completion and commissioning expected in 2009. The foundation engineering design for Tianjin’s 1,000 kt/a ethylene project was completed in June 2007, and it passed the review in August; the key equipment, namely the pyrolysis gas compressor and cryogenic tanks, were made domestically. At present, the three types of machines, the cryogenic tank, and the main tower equipment have been ordered; the technical specifications for the internal components of the tower have also been finalized. On-site construction is progressing as planned, with completion and commissioning expected in 2009. The foundation engineering design for the Zhenhai 1,000 kt/a ethylene project was completed in August 2007, and it passed the review in September; the key equipment, namely the propylene refrigeration compressor and cryogenic tanks, were made domestically. At present, the three types of machines, the cryogenic tank, and the main tower equipment have been ordered; the technical specifications for the equipment inside the tower have also been finalized. On-site construction is progressing as planned, with completion and commissioning expected in 2010. The 800kt/a ethylene project in Wuhan was approved by the **National Development and Reform Commission in April 2007; construction began on December 18, with completion and operation expected by 2011. Once completed, Wuhan will become the first large-scale integrated refining and chemical production base in central China. 3 Key Measures for 2008: In 2008, it is necessary to continue to implement the scientific development concept, aim to enhance competitiveness, focus on improving economic efficiency, strengthen fundamental work and refined management, ensure the safe and stable operation of facilities, advance the construction of new projects as planned, and guarantee the completion of all production and operation tasks for the year. To achieve the goal of producing 6,800 kt/a of ethylene (including Sinopec and Yangzi Petrochemical), it is essential to focus on the following aspects: (1) Strengthening the ‘three basics’ to ensure safe production. Since there was no increase in ethylene production capacity in 2008, to meet the annual production target, it is necessary to further emphasize safe production and strive to improve the operation rate, utilization rate, and reliability of the plants. To address the increase in the number of unplanned shutdowns of the ethylene plant in 2007, it is necessary to focus on strengthening the special maintenance management of large-scale units; particular attention should be paid to the management of weak areas such as instrumentation and electrical systems. Efforts should be made to resolve the issues existing in the unit’s auxiliary systems and utility systems, so as to ensure the plant operates in a stable, continuous, efficient, and safe manner. (2) Leverage the group’s advantages to optimize pyrolysis feedstocks. First, it is necessary to fully tap internal potential; while ensuring the quality of refined oil products and meeting production targets, as much high-quality cracking feedstock as possible should be produced ； At the same time, in accordance with the principle of \"using alkenes where appropriate and aromatics where suitable,\" further efforts should be made to optimize the overall structure of chemical light oils, as well as to carry out regional optimization and \"separate storage and distribution.\" Second, optimize internal resources by making full use of resources such as light hydrocarbons and liquefied gas, and accelerate the progress of new projects for the utilization of catalytic dry gas. Third, building on the work done in 2007, continue to organize special competition activities aimed at improving the yield of \"dienes\". (3) Rely on technological progress to achieve energy conservation and emission reduction. Taking the improvement of the thermal efficiency of the pyrolysis furnace as a starting point, further standardize the operation management and precise control of such furnaces. Continue to promote the use of technologies such as air preheaters and tube twist devices in order to extend the operational life of the pyrolysis furnaces. Enterprises that meet the conditions should put their pyrolysis furnaces into \"cold standby\" mode. Accelerate the application of advanced control technologies to stabilize and optimize the operation of the pyrolysis furnace and separation and recovery systems, thereby achieving economical operation. Further strengthen the operation management of large-scale units to improve their operational efficiency. Strengthen the insulation of equipment and pipelines, as well as the maintenance of steam traps; ensure optimal operation of the steam system; and improve the economic efficiency and energy utilization efficiency of the utility systems. (4) Coordinate maintenance plans and implement technical improvement projects. In 2008, the old Yangzi Ethylene plant and the Zhongyuan Ethylene plant were scheduled for maintenance, with technical improvement projects such as the viscosity reduction of the quench oil at the Zhongyuan Ethylene plant being carried out simultaneously. For these two ethylene plants, it is necessary to carefully optimize the maintenance, shutdown, and startup plans as well as the network schedules; to increase the depth of maintenance efforts and ensure maintenance quality; to develop targeted measures to reduce material loss and consumption of utility resources. At the same time, it is important to organize proper training for employees regarding shutdown and startup procedures to ensure their smooth execution. (5) Deepen efforts to meet standards and improve the level of the facilities. By focusing on enhancing meticulous management, stepping up the oversight and evaluation of compliance efforts, and conducting monthly tracking analyses to address any issues promptly, it is possible to ensure \"stable performance on a monthly basis, which in turn supports annual goals.\" This approach helps to guarantee the safe, stable, and continuous operation of various installations, thereby pushing compliance efforts to a higher level. Organize various ethylene producers to carry out the performance evaluation of olefins for the year 2007; implement cost-reduction measures based on the gap analysis, in order to continuously enhance the competitiveness of their production facilities. (6) Ensure overall coordination to advance project construction. In 2008, the new ethylene project of Sinopec will enter a very critical phase; it is necessary to proceed with the project construction steadily, in accordance with the principle of \"acting cautiously while striving for progress,\" and taking into account the characteristics of each stage. According to the overall plan, the Fujian ethylene plant is to reach mechanical completion by the end of the year; the Tianjin ethylene plant is to complete its detailed design by the end of August, while the Zhenhai ethylene plant is to finish its detailed design by the end of October. The Wuhan ethylene plant is to complete the review of its process package by May, and its foundation design and related reviews are to be completed by the end of the year.