Changing the valve opening degree when the flow volume change is gentle, and stable. When the opening degree percentage from 0% to 100% (stroke), changing the flow percentage increased from 0% to 100%. Conversely, a decrease of nearly 100mm, the whole trip can be easy to adjust. The curve can be seen from Figure 5 the percentage of the valve opening degree and flow check points rate approximated as a linear relationship, so easy to adjust, and the valve to achieve a low flow rate under the high differential pressure. P inlet = 9.4MPa valve inlet port P = 3.2MPa, measured valve (from the valve 30cm) noise 70dB (ordinary regulating valve noise above 84dB), indicating that this labyrinth flow control valve has a good application prospects and enormous economic benefits.
Heavy oil thermal recovery steam injection on the basic requirements of the flow control valve
Note the typical flow of the steam pipe network steam distribution and metering a fixed heavy oil thermal recovery into steam flooding. The three critical issues of the steam injection process in heavy oil development is steam distribution, metering and regulation. Reasonable regulation of the steam to achieve scientific and steam injection, to improve the thermal recovery of oil and gas than oil recovery, so as to get the economic benefits. Heavy oil thermal recovery with a single well steam stimulation and steam drive in two stages. In the whole process of the thermal recovery of the entire block, except initially only single well steam stimulation, a single well stimulation and steam drive simultaneously. Steam Distribution Station To drive well to the stimulation wells and the foreign devils injection allocation. Karamay Oilfield in Xinjiang thermal recovery site, the high pressure of stimulation wells (5 ~ 10MPa), large (6 to 10t / h) flow of steam injection, the steam drive Kat steam injection pressure is low (2 to 5 MPa) steam injection flow (1.5 ~ 5t / h). This means that the distributor to the pressure difference between steam injection wells of different sizes, the related 3MPa or more must be between the distributor and steam injection wells to increase the flow resistance of links to absorb the remaining pressure. Obviously, used herein, the flow regulating valve should be in a small flow rate having a larger buck function, while having a small voltage drop in the large flow. This is the heavy oil thermal recovery steam process the special requirements of the regulating valve. Pursuing a dream, good weaver of dreams
2, the existing steam flow regulating valve and the high differential pressure flow regulating valve a problem
Thermal recovery process, in order to buck, the use of control valve to work with a minimum degree of opening of the valve the steam velocity is high, adjustable, and difficult to achieve the predetermined flow rate value. Combined with a distributor corresponding multi-port steam injection wells, adjust well in traffic will affect other wells flow, which in turn increases the difficulty of the flow regulator. Shengli Oilfield, developed in cooperation with the Xi'an High Pressure Valve Factory JT65Y250V high-pressure steam to adjust the cut-off valve resistance parts for piston-hole regulation structure. Run the test site thermal recovery breathe draw traffic percentage with the percentage of the opening degree curve in Figure 1. Opening degree from 0% to 10%, the flow percentage of more than 60%, the adjustment sensitivity is too large, valve handwheel a movable, excessive either steam flow, or too small to be seen from the curve. In the opening degree of 10% or more to adjust the sensitivity is too low, no regulatory function within the range of 40% to 100% open. Therefore difficult to effectively adjust the steam flow within the scope of the full behave. The valve opening is small, the fluid within the valve reaches the critical flow rate, along with the introduction of the serious problems of vibration and erosion.
Xi'an Jiaotong University researchers designed GYY high differential pressure regulating valve, high pressure drop and flow characteristics improvement, but the critical flow rate is too high makes erosion, vibration, noise, and other more serious problems had to use high-strength, The wear-resistant material. In this way, not only to improve the cost of the valve, and flow with itinerary changes still the regulation characteristics has not improved. In addition, the critical flow is generally require greater than 2 of inlet pressure and backpressure, which limits its eagle. Example, some of the thermal recovery steam injection well requires a pressure of 8 ~ 12MPa or higher, while the outlet of the boiler a maximum pressure of 18MPa is impossible to form the critical flow. In field applications, such pneumatic control valve can not be effectively achieved depends primarily on the last one of the passage area of the high temperature and pressure under a wide range of flow rate adjusting and pressure drop to adjust its flow regulator. This regulation is not fundamentally different from ordinary valves, electric control valve opening degree is still difficult to guarantee the expected traffic. A common financial characteristics of the existing pressure differential flow regulating valve is a high differential pressure will inevitably lead to the high velocity, high velocity brings vibration, erosion, noise, and other serious problems. How to solve these problems is an important research topic that was placed in front of the scientific and technical personnel.
3 new high differential pressure labyrinth steam flow control valve developed
Abroad in regulating valve made some valuable design ideas and methods. Figure 3 is an American design variable flow resistance and a regulator valve spool. Is different from the ordinary valves that its flow area and throttle valve progression, resistance coefficient decreases as the stroke becomes larger, i.e. the flow area of the variable drag coefficient varies inversely with the stroke change. Thus, the spool has a natural bias voltage drop can be corrected in many process control systems, to achieve a small flow large pressure drop or a small pressure drop, of the large flow broad inherent accommodative amplitude. In addition, the use of multi-stage pressure drop, tortuous flow channel to reduce the flow rate and with a low-noise inventory. The actual fluid by the number of the flow channel and the valve opening degree proportional. I.e., the beginning of the valve stroke, only one flow channel is exposed when the opening degree is close to 100%, the maximum number of the flow channel is exposed, the spool in the Figure, the blacked out portion is the actual flow channel. But the introduction of some other problems, such as cutting pieces using the the vertical elbow Shun Shun connection (or the inverse of an inverse connection that forward right angle elbow) to limit the flow resistance coefficient; poor sealing, severe leakage, process complex, high processing costs, and thus this valve does not appear on the domestic market in the United States.
In summary, the heavy oil thermal recovery steam injection process needs a high differential pressure regulating valve, in addition to adapt to the high-temperature, high-pressure two-phase flow of soda media, will encounter a high pressure differential, wide adjustment range, vibration, red eclipse and other special problems. Hereby Petroleum Administration Production Technology Research Institute and the Institute of Nuclear Technology Design and Research Institute to carry out joint research guiding ideology as much as possible to increase the drag coefficient of the valve, high pressure low flow, and fundamentally ease erosion and noise inherent flow of good regulation performance and a wide amplitude of accommodation.
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