Slurry valves and slurry pipelines appeared and developed simultaneously in China. A slurry valve is an important part of slurry pipeline system. And its investment is the highest, accounting for about one fifth of the total investment of pipeline engineering. At present, the commonly used slurry valves mainly include ball valves, plug valves, gate valves, knife gate valves and so on. The slurry valve is optimized and improved on the basis of the general valve structure. Compared with other general valves, the slurry valve has more severe service conditions, mainly used in high temperature, high pressure, strong corrosion, strong abrasion and other environmental conditions. The slurry valve needs high quality wear resistant materials, strict sealing structure, special anti clogging design and powerful actuators. Therefore, the slurry valve structure is derived from the traditional valve, and its quality and cost are higher than those of the general valve.
Knife gate valve
Knife gate valves have the advantages of simple structure, small volume, simple operation and maintenance, and low cost. It is widely used in slurry pipeline at low temperature and low pressure. The maximum nominal diameter of domestic slurry knife gate valve is DN 1600 and the maximum nominal pressure is 4.0Mpa. It has main disadvantages of short service life (generally 1 to 10 years), easy leakages, high failure rates and high maintenance costs.
Knife gate valves have the advantages of simple structure, small volume, simple operation and maintenance, and low cost. It is widely used in slurry pipeline at low temperature and low pressure. The maximum nominal diameter of domestic slurry knife gate valve is DN 1600 and the maximum nominal pressure is 4.0Mpa. It has main disadvantages of short service life (generally 1 to 10 years), easy leakages, high failure rates and high maintenance costs.
Ball valve
Ball valve is evolved from the plug valve. The ball is rotated 90 ° around the axis of the valve stem to open and close the valve. The slurry ball valve has main advantages of long service life, compact structure, high pressure resistance, strong wear resistance and corrosion resistance, small fluid resistance, quick switch, good sealing performance and wide application ranges. The slurry ball valve has main disadvantages of complex structure, large volume, high costs, being easy to lock valves when it is opened and closed in slurry. With the development of new wear resistant materials and spraying technology, the service life of slurry ball valve can be doubled by spraying stellite alloys (STL), nickel base alloys, chromium carbide (Cr3C2), tungsten carbide (WC) and other wear resistant coatings. The slurry ball valve with full bores, high pressure, large diameters, two-way sealing and long service life has gradually replaced other types of valves and becomes the preferred valve for long-distance high-pressure slurry pipelines. There are many ball valve manufacturers in China, with the maximum nominal pressure of 42MPa and the maximum nominal diameter of DN3000. The maximum diameter of ball valve which has been put into use in domestic slurry pipeline is DN600 and the maximum working pressure is 25MPa, which have reached the international equivalent product level. However, there are still gaps in the processing accuracy, materials and structure design between domestic high pressure wear resistant valves and foreign advanced technology. For both oil and gas pipelines and slurry pipelines, ball valves at key positions are still mainly imported products.
Ball valve is evolved from the plug valve. The ball is rotated 90 ° around the axis of the valve stem to open and close the valve. The slurry ball valve has main advantages of long service life, compact structure, high pressure resistance, strong wear resistance and corrosion resistance, small fluid resistance, quick switch, good sealing performance and wide application ranges. The slurry ball valve has main disadvantages of complex structure, large volume, high costs, being easy to lock valves when it is opened and closed in slurry. With the development of new wear resistant materials and spraying technology, the service life of slurry ball valve can be doubled by spraying stellite alloys (STL), nickel base alloys, chromium carbide (Cr3C2), tungsten carbide (WC) and other wear resistant coatings. The slurry ball valve with full bores, high pressure, large diameters, two-way sealing and long service life has gradually replaced other types of valves and becomes the preferred valve for long-distance high-pressure slurry pipelines. There are many ball valve manufacturers in China, with the maximum nominal pressure of 42MPa and the maximum nominal diameter of DN3000. The maximum diameter of ball valve which has been put into use in domestic slurry pipeline is DN600 and the maximum working pressure is 25MPa, which have reached the international equivalent product level. However, there are still gaps in the processing accuracy, materials and structure design between domestic high pressure wear resistant valves and foreign advanced technology. For both oil and gas pipelines and slurry pipelines, ball valves at key positions are still mainly imported products.
Plug valve
The principle of slurry plug valve is similar to that of ball valve, which is mainly divided into four types, namely the regular type, short type, venturi type and full bore type. The plug of plug valve is cylindrical or conical, and the flow passage is generally trapezoidal. Therefore, compared with the same type of ball valves, the sealing surface of plug valve is much larger than that of the ball valve. Moreover, the slurry pipeline can be used as a wear resistant regulating valve with simple structure and low costs. The main disadvantages of plug valves are that the torque is too large, and the operation is not flexible. It needs to be sealed with grease, and the nominal size is small (generally not more than DN600). There are a large number of plug valve enterprises in China, but the manufacturing scale is small. The products are mainly small sized plug valves, which are generally used for long-distance pipeline. The wear resistant plug valve with large sizes and high pressure in slurry pipeline is mainly imported. Since the function of plug valves is equivalent to that of ball valves, and the cost is lower than that of ball valves. Plug valves still have a wide application space in slurry pipelines.
Prospect of slurry valve
Slurry pipeline experts at home and abroad agree that long-distance pipelines will develop in the direction of larger diameters, higher pressure, higher steel grades, more media and more intelligent in the future.
The transformation and improvement of structure, materials and finishing levels of domestic slurry valves from general valves to slurry special valves should be strengthened. Efforts should be made to improve the research and development level of slurry valve equipment with large sizes, high pound grades, strong wear resistance and corrosion resistance, good sealing performance and high degree of automation, especially for ball valve, and improve the intelligent level and reliability of valve actuator. In addition, special equipment for slurry pipeline systems such as inlet and exhaust valves, safety valves, regulating valves, orifice plate and bursting disc still have many technical gaps and deficiencies in China. It is necessary to encourage domestic enterprises to independently develop, produce and improve the quality and performance of existing products.
Future
Since the development of slurry pipeline technology in China, the software strength and hardware conditions have been steadily improved. R & D, manufacturing and application level of main equipment and materials such as pumps, pipes and valves have been improved rapidly. The core technology and key equipment of long-distance pipeline transportation systems have gradually owned independent intellectual property rights. Although there are still some gaps in processing accuracy, materials and structural design of some high-pressure and large flow domestic pipeline transportation equipment compared with foreign advanced technology level, with the construction and implementation of Shenwei coal transportation pipeline project independently designed and built in China, the long-distance slurry pipeline made in China is just around the corner. China's slurry pipelines will strive to achieve the grand goal of digital, safe and green pipeline.
Slurry pipeline experts at home and abroad agree that long-distance pipelines will develop in the direction of larger diameters, higher pressure, higher steel grades, more media and more intelligent in the future.
The transformation and improvement of structure, materials and finishing levels of domestic slurry valves from general valves to slurry special valves should be strengthened. Efforts should be made to improve the research and development level of slurry valve equipment with large sizes, high pound grades, strong wear resistance and corrosion resistance, good sealing performance and high degree of automation, especially for ball valve, and improve the intelligent level and reliability of valve actuator. In addition, special equipment for slurry pipeline systems such as inlet and exhaust valves, safety valves, regulating valves, orifice plate and bursting disc still have many technical gaps and deficiencies in China. It is necessary to encourage domestic enterprises to independently develop, produce and improve the quality and performance of existing products.
Future
Since the development of slurry pipeline technology in China, the software strength and hardware conditions have been steadily improved. R & D, manufacturing and application level of main equipment and materials such as pumps, pipes and valves have been improved rapidly. The core technology and key equipment of long-distance pipeline transportation systems have gradually owned independent intellectual property rights. Although there are still some gaps in processing accuracy, materials and structural design of some high-pressure and large flow domestic pipeline transportation equipment compared with foreign advanced technology level, with the construction and implementation of Shenwei coal transportation pipeline project independently designed and built in China, the long-distance slurry pipeline made in China is just around the corner. China's slurry pipelines will strive to achieve the grand goal of digital, safe and green pipeline.
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