With the development of foreign large-scale complete sets of technology, a series of new complete sets of equipment and single machine have appeared. The characteristics of the development of new complete sets of equipment related to valves are large-scale, high parameter, high-performance automation and complete set, which are suitable for the control mode of these complete sets of equipment. In the past 20 years, the control methods of foreign valves have also developed greatly. In addition to the general manual, mechanical, electric, pneumatic, hydraulic transmission, electro-hydraulic, pneumatic, automatic control valve varieties continue to increase, and there is a further development trend.
For example, oil refining equipment. The largest refineries are 36.4 million tons / year (Virgin Islands in the Caribbean Sea) and 30 million tons / year (Venezuela). At present, there are nearly 30 refineries with a capacity of more than 20 million tons / year; the processing capacity of the largest unit oil refining decompression unit reaches 24 million tons / year, the catalytic cracking unit reaches 8.24 million tons / year, and the hydrocracking unit reaches 3.2 million tons / year. With the large-scale installation, the valves are becoming larger and larger, and the control mode is also developing towards automation.
In recent years, the development of long-distance pipeline is very fast. The main reasons are: low cost, only 1 / 3 of railway transportation; 2. Buried underground, not easy to destroy; 3. Fast construction speed and low investment. Therefore, the demand of valves for long-distance pipeline has increased greatly in recent years. The maximum unit capacity of power generation equipment is 1.3 million KW for double shaft thermal motor unit, 1.2 million KW for single shaft thermal power unit and 1.3 million KW for nuclear power unit.
The maximum diameter of flat gate valve is 1620 mm and 2000 mm; the maximum diameter of butterfly valve is 9750 mm; the maximum diameter of ball valve is 3050 mm; the weight of valve without driving device is 184 tons; the maximum diameter of water gate valve is 2750 mm and the pressure is 9 MPa.
The economic effects of large-scale equipment can be summarized as follows: first, improving production efficiency; second, reducing infrastructure investment; third, reducing the consumption of raw materials and fuels. With an annual processing capacity of 5 million tons of oil refining equipment compared with 1 million tons, the investment in production capacity per ton of products is reduced by 50%. Compared with two 3 million T / a refineries, the investment of a 6 million T / a oil refinery is only 69% of the latter, the steel consumption is 53%, the floor area is 54%, the production cost is 75%, and the labor productivity is increased to 170%.
As the automation level of complete sets of equipment is higher and higher, the main production processes of foreign petrochemical enterprises have realized direct digital control, and some have also realized computer hierarchical control. Chemical enterprises such as synthetic ammonia ethylene, urea, synthetic fiber, synthetic rubber and synthetic plastics have generally realized patrol inspection and alarm, and some enterprises have realized partial automatic control.
At present, computer control is widely used in foreign large-scale generating units of more than 200000 kW; computer control is widely used in nuclear power plants; computer control is used in many countries for long-distance pipeline system, and microwave communication system is installed; only two or three persons on duty are needed in the general control room, and the working conditions of the whole line can be monitored through television.
With the improvement of various complete sets of equipment, process flow and performance, the series of valves abroad are still increasing, and many new types of valves have appeared in recent years. Such as: emergency shut-off valve, fast on-off valve, fire damper, anti-static valve, temperature and pressure reducing valve, butterfly check valve, pressure relief valve, vacuum jacketed valve, water-cooled or air-cooled valve, safety gate valve, safety stop valve and other new valves, among which ball valve, butterfly valve and flat gate valve are the fastest-growing valve varieties in the past 20 years.