In recent years, the development of long distance pipeline is rapid, the main reason is low cost, only equal to one third of the railway transportation; The second is buried in the ground, not easy to destroy; Third, the pipeline construction speed is fast, the investment saves. As a result, the demand for valves in long - distance pipelines has increased in recent years. The maximum unit capacity of power generation equipment: biaxial thermal power unit l300,000 kW, single-axle thermal power unit 1.2 million kW, and the maximum nuclear power unit 1.3 million kW. The largest plate gate valve with the complete set of equipment has a diameter of 1620mm and 2000mm. Maximum butterfly valve size 9750mm; The maximum ball valve size is 3050mm, excluding the weight of the drive device valve reaches 184 tons; Maximum water gate valve size 2750mm, pressure up to 9MPa.
The economic effects of the upsizing of equipment can be summarized as: first, to improve production efficiency; second, to reduce investment in infrastructure; third, to reduce consumption of raw materials. Investment per tonne of production capacity is reduced by 50 per cent, compared with 1 million tonnes of annual processing capacity. A 6 MMT/yR refinery costs only 69% as compared to two 3 MMT/yR refineries, consumes 53% steel, occupies 54% of the floor space, costs 75%, and increases labor productivity to 170%. As the automation level of complete sets of equipment is getting higher and higher, the main production process of foreign petrochemical enterprises has realized direct digital control, and some have realized computer hierarchical control. Chemical enterprises, such as synthetic ammonia ethylene, urea, synthetic fiber, synthetic rubber and synthetic plastics, generally realize circuit detection and alarm, and some enterprises have realized partial automatic control.
At present, overseas large generator sets of more than 200,000 kW are generally developed to computer control. Nuclear power stations are generally controlled by computers; Many countries use computer to control the long-distance transmission pipeline system, and it is equipped with microwave communication system. The total control room only needs two or three watchmen, who can monitor the working condition of the whole line through TV. With the improvement of all kinds of complete sets of equipment, technological process and performance, the series varieties of foreign valves are still increasing, and many new varieties of valves have appeared in recent years. Such as: emergency cut-off valve, quick switch valve, fire dampers, anti-static type valve, and the temperature and pressure-releasing valve butterfly check valve, relief valve, vacuum jacketed valve, water cooled or air cooled valve, safety valve, safety valve, and other new valve, in one of the common valve ball valve, butterfly valve, and varieties of flat gate valve is one of the fastest growing in 20 years.
