This paper reviews the overall situation of SINOPEC’s ethylene business in 2019, briefly summarizes the ethylene business from the aspects of environmental protection, feedstock optimization, energy saving and consumption reduction, technology research, long-term operation and maintenance, and puts forward the objectives and important tasks in 2020.

This paper summarizes the development of PetroChina's ethylene business in 2019, including the ethylene production, ethylene yield, yields of ethylene and propylene, processing loss ratio and energy consumption of its subordinate petrochemical enterprises, as well as feedstock optimization, long-term operation, maintenance, technical modification and technical measures. The focus of work concerning long-term optimum operation of ethylene plant in 2020 is put forward.

 Based on the development of process technology and catalytic technology for the synthesis of ethylene oxide from ethylene, the technical progress in the synthesis of ethylene oxide from ethylene is reviewed. Ethylene oxide is widely used in chemical, medical, military, washing, printing, dyeing and other fields. The existing synthesis technology is the direct oxidation of ethylene, and silver is commonly used as the catalyst. The developing trend is to optimize the existing process, improve the performance of silver catalyst and study the side reaction inhibitors.

This paper introduces the overhaul of the No.2 Ethylene Plant of PetroChina Jilin Petrochemical Company in 2018. Starting from process management, the Company actively optimized the work program, solved the key and difficult problems, shut down the plant for propylene recovery, and took some measures such as adopting high efficiency cleaning agent and speeding up high pressure seal of the system, which achieved good effect.

-added pipelines during the shutdown. These methods not only improved the economic efficiency, but also greatly reduced the workload of subsequent stages. On the other hand, through continuous practice and exploration, a set of characteristic disposal methods were formed in the aspects of equipment steaming, which effectively decreased the VOC emissions.

Quench system is the core component of ethylene plant. Its operation directly affects the long-term and stable production of ethylene plant. It is necessary to strictly control the process operation indexes of quench oil, quench water and dilution steam generation systems in order to ensure the long-term safe and stable operation of ethylene plant and improve the market competitiveness and economic benefits of the plant.

Plate-fin heat exchanger, as the core equipment in the cryogenic separation process of ethylene plant, can realize heat exchange between multi-strand materials. Therefore, it has large volume, complex structure and long purchasing cycle, and is mainly imported from abroad. Once this equipment leaks, the manufacturer will be unable to supply a new one in a short period of time, and the production plant will have to be shut down for a long time. Localized large plate-fin heat exchanger applied in the cryogenic section of ethylene plant has the same performance as the imported equipment, and it has the advantages of short purchasing cycle, quick after-sale service and remarkable saving of funds, showing ideal service effect.

 This paper introduces the methanol cleaning of cold box during the overhaul of the 1.0 Mt/a ethylene plant at SINOPEC SABIC Tianjin Petrochemical Co., Ltd. in 2016. By summarizing the principle of NO_X causing danger, the development of methanol cleaning scheme, the treatment of process system and the quality control of cleaning, some corresponding measures are formulated against the problems emerged in the cleaning, thus ensuring the smooth completion of the methanol cleaning of cold box.

The high viscosity of quench oil is one of the important factors affecting the long-term stable operation of ethylene plant, and increases the energy consumption of ethylene plant. On-line viscosity measurement has always been a difficulty in the design and production of ethylene plant. The main reasons are the high temperature of on-line measurement and the low on-line viscosity. The temperature and methods for laboratory sampling measurement are usually different from those of on-line viscosity measurement methods, leading to errors in the selection of on-line measuring instruments and the inability to compare the measured data directly. Therefore, on-line viscosity measurement has attracted more and more attention. Through a measurement case, this paper analyzes the relationship between on-line viscosity and laboratory viscosity of quench oil, and accordingly puts forward some solutions to on-line viscosity measurement.

New chemical cleaning method for quench system is introduced against the traditional cleaning method. From the perspectives of cleaning time, cleaning effect, waste water and oil generation and cleaning method, the traditional cleaning method and two chemical cleaning methods are compared and analyzed. The experience in chemical cleaning process evaluation, precautions, acceptance criteria and other aspects are summarized, and the shutdown time and economic loss of ethylene plant that can be reduced by chemical cleaning are calculated.

The old ethylene plant of PetroChina Dushanzi Petrochemical Company adopts the technology of Lummus (USA). It was designed and constructed by SNAM (UK) with a design capacity of 140 kt/a. In the transformation in 2002, it was expanded from 5 cracking furnaces to 7 cracking furnaces, and its capacity reached 220 kt/a. In 2017, the adjusted nitrogen oxide content in the flue gas of cracking furnace could meet the national standard (< 180 mg/m3), but fluctuated around 170 mg/m3, resulting in low operating flexibility of cracking furnace, so the demand of high load production could not be met. In order to reduce the nitrogen oxide content in the flue gas of cracking furnace and improve the operating flexibility of cracking furnace, the burners of the seven cracking furnaces in the old ethylene plant in Dushanzi were revamped for low nitrogen content. After the transformation, the nitrogen oxide content is required to be less than 100 mg/m³ as stipulated in the new national standard.

The long-standing problem of the great fluctuation in outlet temperature of the quench cooler A (L-101A) in the No.1 cracking furnace easily led to the coking during the secondary reaction of cracking gas and affected the subsequent system. The cooling medium of the quench cooler was replaced, the original process water was changed to purified water, and the actual data before and after the transformation was compared and analyzed. The outlet temperature of the quench cooler was stabilized by optimizing the cooling medium, and the decoking cycle of the quench cooler A (L-101A) in the No. 1 cracking furnace was prolonged.

This paper introduces the heat transfer principle of the radiation and convection chambers of cracking furnace, analyzes the changes in temperature distribution in the radiation chamber after using low-oxygen burners, and presents the adjustment method for optimizing the combustion heat transfer in radiation chamber of furnace. Through the analysis of the current exhaust flue gas and thermal efficiency detection methods, a method for inspecting the operation of furnace by detecting the carbon monoxide content in exhaust flue gas.

The polymer content of styrene product of the 27 kt/a pyrolysis gasoline extraction unit at SINOPEC Zhenhai Refining and Chemical Company has fluctuated greatly since its start-up in this operation cycle, and the effect of measures such as optimizing process parameters and solidifying on-site operation was limited. Finally, the problem of high polymer content of styrene product was effectively solved by trying out new polymerization inhibitor and optimizing injection position, the product quality grade was improved, the tar production was reduced, and both the environmental benefit and economic benefit were achieved.