As the West-East Gas Pipeline project of the Century Project, the main pipeline has a long distance, large temperature changes along the line, high transmission pressure, and a wide range of users. How to ensure the long-term, safe, and stable operation of the pipeline is of great significance. The goal is based on the fact that the interior of the pipeline should be clean and dry to ensure that no gas hydrates are formed anywhere in the pipeline system.
Pipeline drying method is not the same At present, there are mainly three kinds of construction methods applied to pipe drying, namely desiccant drying method, vacuum drying method and dry air drying method. Among them, the desiccant drying method generally uses methanol, ethylene glycol or triethylene glycol as a desiccant. The desiccant and water can be mutually soluble in any proportion, the vapor pressure of the water in the formed solution is greatly reduced, so as to achieve the purpose of drying. The desiccant remaining in the pipeline is also a hydrate inhibitor and can inhibit the formation of hydrates. In the actual application process, since the price of ethylene glycol or triethylene glycol is relatively high, methanol is generally used as a desiccant. The vacuum drying method is a method in which a vacuum pump is used under controlled conditions to remove free water in the tube by reducing the pressure in the tube. The principle is to create a vacuum pressure corresponding to the temperature inside the tube, so that the moisture attached to the inner wall of the tube boils and vaporizes.
At present, dry air drying method is widely used in our country. There are two methods of dry air drying: the first is the direct application of dry air to purge the pipeline; the second is the use of ball-passing methods to dry the pipeline. From the aspect of drying efficiency and effect, the former is inferior to the latter; in terms of application scope, the latter is applicable to the diameter pipeline, while the former is applicable to all pipelines, including reducing pipelines.
The dry air purging and drying method is to blow dry air into the pipeline at low pressure, and the low dew point air has the ability to absorb moisture to achieve the purpose of drying the pipeline. In an ideal situation, the water in the pipeline is adsorbed by low dew point dry air and is blown out of the pipeline by the dry air behind. In practice, however, it is impossible for dry air to completely blow wet air that has absorbed moisture out of the pipe. Although the drying efficiency of this drying method is not high, it is not possible to pass the pig to the reducing pipeline. If dry air is used for the pipeline drying, this construction method can only be applied.
The dry air ball drying method is to place one or more foam pigs in advance in the pipeline, and the low dew point dry air is used to push the pigs to advance in the pipelines, and the dry air and wetness are achieved through the isolation of the pigs. Air replacement process. This drying method is suitable for the drying of pipelines with long-distance through-diameter pipelines. It is also the main dry construction method in the drying of trunk pipelines in the West-East Gas Pipeline.
In the past two years, vacuum vacuum drying technology has been gradually applied in China. Its development prospects are as described by the owners of the Zhujiang-Zhongshan Natural Gas Pipeline (Zhonghai Guangdong Natural Gas Co., Ltd.) and the supervisor (Beijing Xingyou Supervision Company) that adopted this new technology for the first time in China: “Whether it is a dew point or a drying effect. Vacuum drying has advantages over dry air drying, which has a longer application time in China. In the future pipeline construction, this technology will be popularized and applied."
Unlimited pipeline drying prospects Pipeline drying currently has a large market. The pipelines under construction and to be built in China must be dried. At present, any high-standard pipeline abroad, whether it is a pressure test or a hydrostatic test, must be dried. Therefore, for a specialized pipeline construction team, the process technology of pipeline drying must be mastered. Relevant experts also said on many occasions that due to the large number of pipeline drying methods, European companies mostly use vacuum drying; the United States, Canada, etc. adopt the dry air method. Because these methods are undifferentiated, in the project bidding, it is often determined according to the preferences of the owners and what technology to take. In order to better enter the international market, we should make beneficial attempts on these drying methods.
The China National Petroleum Pipeline Bureau, the main force in the construction of domestic pipelines, has already made pipeline pre-production, including pipeline drying, a key development. In order to complete the task of desiccating the West-East Gas Pipeline on schedule, the Pipeline IV Company has introduced several large-displacement air compressors and drying devices from abroad, forming the construction capacity of three units, which has become a domestic drying field. The strongest professional company. The pipeline drying construction project of 800 kilometers in the east section of the West-East Gas Pipeline completed by the company has been recognized and appreciated by the owners with excellent results of acceptance rate of 100%. Wang Xin, the deputy manager of the company's pressure sweeping branch office, said that in fact, the pipeline drying technology is not used in foreign countries for a long time. The technology is not very mature. It comes from a foreign company that also participates in the dry gas construction tasks of the West-East Gas Pipeline. Look, they only have certain drying procedures, and they have not formed normative and mature construction technologies. With respect to the effect and duration of pipeline drying, domestic drying technology has reached an international advanced level.
On the basis of mastering the dry air drying technology, the Pipeline IV pre-commissioning management center has entered the unique vacuum drying market in China, and adopted vacuum drying technology in Libya's pipeline construction and received good results. On December 12 last year, the vacuum drying technology was first applied to the Zhujiang-Zhongshan Natural Gas Pipeline Project in China, further fulfilling the goal of the technology of "contending for domestic and moving toward the world".
Looking ahead, with the rise of pipeline construction, the development of pipeline drying technology will have unlimited prospects.
Pipeline drying method is not the same At present, there are mainly three kinds of construction methods applied to pipe drying, namely desiccant drying method, vacuum drying method and dry air drying method. Among them, the desiccant drying method generally uses methanol, ethylene glycol or triethylene glycol as a desiccant. The desiccant and water can be mutually soluble in any proportion, the vapor pressure of the water in the formed solution is greatly reduced, so as to achieve the purpose of drying. The desiccant remaining in the pipeline is also a hydrate inhibitor and can inhibit the formation of hydrates. In the actual application process, since the price of ethylene glycol or triethylene glycol is relatively high, methanol is generally used as a desiccant. The vacuum drying method is a method in which a vacuum pump is used under controlled conditions to remove free water in the tube by reducing the pressure in the tube. The principle is to create a vacuum pressure corresponding to the temperature inside the tube, so that the moisture attached to the inner wall of the tube boils and vaporizes.
At present, dry air drying method is widely used in our country. There are two methods of dry air drying: the first is the direct application of dry air to purge the pipeline; the second is the use of ball-passing methods to dry the pipeline. From the aspect of drying efficiency and effect, the former is inferior to the latter; in terms of application scope, the latter is applicable to the diameter pipeline, while the former is applicable to all pipelines, including reducing pipelines.
The dry air purging and drying method is to blow dry air into the pipeline at low pressure, and the low dew point air has the ability to absorb moisture to achieve the purpose of drying the pipeline. In an ideal situation, the water in the pipeline is adsorbed by low dew point dry air and is blown out of the pipeline by the dry air behind. In practice, however, it is impossible for dry air to completely blow wet air that has absorbed moisture out of the pipe. Although the drying efficiency of this drying method is not high, it is not possible to pass the pig to the reducing pipeline. If dry air is used for the pipeline drying, this construction method can only be applied.
The dry air ball drying method is to place one or more foam pigs in advance in the pipeline, and the low dew point dry air is used to push the pigs to advance in the pipelines, and the dry air and wetness are achieved through the isolation of the pigs. Air replacement process. This drying method is suitable for the drying of pipelines with long-distance through-diameter pipelines. It is also the main dry construction method in the drying of trunk pipelines in the West-East Gas Pipeline.
In the past two years, vacuum vacuum drying technology has been gradually applied in China. Its development prospects are as described by the owners of the Zhujiang-Zhongshan Natural Gas Pipeline (Zhonghai Guangdong Natural Gas Co., Ltd.) and the supervisor (Beijing Xingyou Supervision Company) that adopted this new technology for the first time in China: “Whether it is a dew point or a drying effect. Vacuum drying has advantages over dry air drying, which has a longer application time in China. In the future pipeline construction, this technology will be popularized and applied."
Unlimited pipeline drying prospects Pipeline drying currently has a large market. The pipelines under construction and to be built in China must be dried. At present, any high-standard pipeline abroad, whether it is a pressure test or a hydrostatic test, must be dried. Therefore, for a specialized pipeline construction team, the process technology of pipeline drying must be mastered. Relevant experts also said on many occasions that due to the large number of pipeline drying methods, European companies mostly use vacuum drying; the United States, Canada, etc. adopt the dry air method. Because these methods are undifferentiated, in the project bidding, it is often determined according to the preferences of the owners and what technology to take. In order to better enter the international market, we should make beneficial attempts on these drying methods.
The China National Petroleum Pipeline Bureau, the main force in the construction of domestic pipelines, has already made pipeline pre-production, including pipeline drying, a key development. In order to complete the task of desiccating the West-East Gas Pipeline on schedule, the Pipeline IV Company has introduced several large-displacement air compressors and drying devices from abroad, forming the construction capacity of three units, which has become a domestic drying field. The strongest professional company. The pipeline drying construction project of 800 kilometers in the east section of the West-East Gas Pipeline completed by the company has been recognized and appreciated by the owners with excellent results of acceptance rate of 100%. Wang Xin, the deputy manager of the company's pressure sweeping branch office, said that in fact, the pipeline drying technology is not used in foreign countries for a long time. The technology is not very mature. It comes from a foreign company that also participates in the dry gas construction tasks of the West-East Gas Pipeline. Look, they only have certain drying procedures, and they have not formed normative and mature construction technologies. With respect to the effect and duration of pipeline drying, domestic drying technology has reached an international advanced level.
On the basis of mastering the dry air drying technology, the Pipeline IV pre-commissioning management center has entered the unique vacuum drying market in China, and adopted vacuum drying technology in Libya's pipeline construction and received good results. On December 12 last year, the vacuum drying technology was first applied to the Zhujiang-Zhongshan Natural Gas Pipeline Project in China, further fulfilling the goal of the technology of "contending for domestic and moving toward the world".
Looking ahead, with the rise of pipeline construction, the development of pipeline drying technology will have unlimited prospects.
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