COCR is a new process using fluidization technology to produce olefins from methanol and heavy olefins at a reaction temperature of about 570 ℃, a regeneration temperature of about 675 ℃ and an ethylene and propylene yield of over 35％. Relying on the mature fluidization process platform, COCR technology has high reliability. The coupling of exothermic and endothermic reactions of methanol and heavy olefin cracking can be achieved, and the heavy olefin resources can be comprehensively utilized. It has a wide application prospect.

In ethylene plant, dry flare gas needs to be superheated before it joins with wet flare gas. Several commonly used superheating methods are introduced in this paper, including natural heating, jacket heating and superheating via superheater. The design principles, technical characteristics and operation characteristics of these methods are discussed, and their advantages and disadvantages in preventing freeze blockage and reducing the consumption of low temperature materials are compared and analyzed. It is concluded that direct superheating via superheater has high safety and reliability and the lowest investment.

The closed cooling water system at Zhongtian Co-founder of Energy Co., Ltd. is one of the few super large closed circulation cooling water systems in Chinese chemical industry. The materials of the system include carbon steel, stainless steel and aluminum. Desalted water is used as makeup water, and the cooling water is highly corrosive. At the initial stage of unit startup, no agent was used in the closed circulation cooling water system, resulting in the corrosion of system and the increased total iron and turbidity. After using the automatic dosing system and water treatment agent of a company, the total iron, turbidity, corrosion rate and other water quality parameters of the system were well controlled.

This paper discusses the problems in the long-term operation of vapor dryer in the No. 1 ethylene plant at SINOPEC Maoming Company including the overhigh water content of outlet cracking gas and the high pressure difference. After taking some optimization measures such as extending the constant temperature time of regeneration of the dryer V-370A from 2~4 hours to 6 hours and shortening the regeneration time of the standby dryer V-370B, the smooth operation of the plant could be maintained for a certain period of time. By replacing the molecular sieves online, the problem of drying failure caused by molecular sieve pulverization could be completely solved. According to the degree of pulverization of molecular sieves in various parts of the bed, the causes of molecular sieve pulverization and the impact of pulverization on drying effect are analyzed, and corresponding improvement measures are put forward.

Tail gas distillation column is a key component of the cryogenic separation unit in front-end depropanization front-end hydrogenation process. It separates ethylene, ethane, methane and hydrogen for the purpose of reducing ethylene loss, improving ethylene yield, and reducing the cooling load of demethanizer, ethylene refrigeration compressor and propylene refrigeration compressor. Based on the operation analysis of the tail gas distillation column under high load, the factors influencing the operation of tail gas distillation column are discussed under the condition that the system equipment of tail gas distillation column and the cracking conditions remain unchanged. Through operation adjustment and technical transformation, the long-term, full-load and high-quality operation of the system under high load was achieved.

The pyrolysis gasoline hydrogenation unit of megaton ethylene plant at PetroChina Dushanzi Petrochemical Company was started up using high sulfur naphtha, and the sulfur content of products repeatedly exceeded the standards for a long time during the startup, greatly prolonging the startup time. The root causes of this problem were found by comparing and analyzing the system operation, catalyst performance and sulfur-containing materials in naphtha. Through the operation optimization of the revamped pyrolysis gasoline hydrogenation unit, the objectives of shortening startup time and reducing energy consumption were achieved.

Since the 1,000 kt/a ethylene plant at PetroChina Dushanzi Petrochemical Company was started up, frequent leakage has been found in the medium pressure condensate line in DS superheater. This paper uses chemical calculation to analyze the deviation of DS pressure, finds out that the fundamental reasons for the frequent leakage of medium pressure condensate line in DS superheater E-3014 were the gas-liquid two-phase flow and the large flow overload erosion, and puts forward some optimization suggestions and effective measures.

At present, ethylene plant is generally started up in the reverse sequence. Propylene refrigeration compressor and ethylene refrigeration compressor are started first, and then cracking gas compressor is started and nitrogen is introduced. Nitrogen is used as the medium and ethylene and propylene are used as the cold agent to precool the cryogenic systems such as cold box and demethanizer, and ethylene and propylene are introduced to achieve the total reflux operation of ethylene rectification column and propylene rectification column. After the precooling of cryogenic systems, natural gas is introduced into the cracking gas compressor to pre-start the separation system in advance, so as to get through the whole process from cracking gas compressor to cold box, demethanizer, deethanizer, high-pressure depropanizer and C₂ hydrogenation reactor.

This paper mainly introduces various advanced energy saving technologies for CBL cracking furnace, including energy saving technologies for radiation section, convection section and other equipment. The characteristics of energy saving technologies are analyzed, and the revamping effect is illustrated through examples. Practice has proved that CBL cracking furnace, which integrates various energy saving technologies, has advanced technology and remarkable energy saving effect.

In this paper, the causes of the corrosion of the fourth stage outlet heat exchanger of cracking gas compressor in the 1.0 Mt/a ethylene plant at PetroChina Dushanzi Petrochemical Company are analyzed. The reason is that the acid substances in gas condensate water corrode the carbon steel equipment. By taking some measures including adding corrosion inhibitor, the corrosion was eliminated and the operation cycle of the heat exchanger was prolonged.