At present, many countries in the world have produced vacuum degasser used in drilling industry. The vacuum degasser has become essential device in mud purification system. The development of vacuum degasser in America is early. Since 80’s America produced a shunt type vacuum degasser. After several times’ improvements, the structure was improving and perfect gradually. For instance, the volume of Swaco horizontal vacuum degasser is huge in order to increase the thin layer area. After that, the British produced a scroll vacuum degasser that has the advantages of simple structure, light weight and convenient installation. But its efficiency is low. So far development of vacuum degasser of America is still in a leading position in abroad, just like Brant screen of America is a leading screen.
On the foundation of introduction, digestion and absorption of foreign advanced design and manufacturing technique, the domestic development of vacuum degasser is quite fast. And then it gradually forms a serialized, large scale industry. At present, the development of vacuum degasser in China is still in the imitation stage. The equipment is relative heavy and anti corrosion ability is not enough; especially the extent of automation is low.
Although the development of vacuum degasser is fast, the development of its Derrick shaker is slow. The vacuum degasser in early age hasn’t control system design. Because of the underground mud density, gas content, viscosity and many other uncertain factors, the main motor and the vacuum pump is difficult to achieve the matching. Therefore drilling fluid often overflows the tank and the accident rate is high. Later, people invented a mechanical device that has control system to control the opening and closing of the gas channel valve. The accident rate obviously decreased. But the structure of the device is very large, so it will take up large space of vacuum degasser. Further more it is mainly used for horizontal vacuum degasser. The device often gets stuck or malfunctions due to inflexible rotation. While vertical vacuum degasser generally do not install the device because of limited space. The tank vacuum extent is only determined by workers observing readings of vacuum gauge.
Nowadays with the development of vacuum degasser, most of the vacuum degassers in the domestic adopt the manual control valve to adjust the vacuum extent. When the equipment starts, it needs personnel to adjust valve. The manual operation by people is not quantitative, which makes the adjusting time long. Once there is fault in adjusting, it will lead to too high vacuum extent, and then drilling fluids will inflow into the suction pipe, causing damage to the equipment. The drilling fluid performance parameter and the gas content are both different, so adjusting range is not the same, which brings much inconvenience to the operation. In view of the above questions, now we develop the automatic control valve. It can control the air input by using the liquid height in vacuum degasser, so that the vacuum extent can be controlled in the working range of vacuum degasser. The application of the valve realizes unattended operation and improves the automation extent of vacuum degasser.