| The high viscousity petroleum with high freezing point contributes 80% of the total oil production in China. In Jiangsu Oilfield, this kind of oil is transported by a Three-pipe Heat-tracing Oil/Gas Gathering and Transferring System to reduce its viscosity. Only 20% of the heat energy is effectively absorbed by well liquid in the tree-like heat supply network operated under high flow rate, high temperature and small temperature difference, which leads to significant hot water supply mismatch and energy loss. The energy consumption for the heat supply in the tree-like network is more than 50% of the total in the oilfield. Therefore there exists great energy saving potential in the three-pipe heat-tracing oil/gas gathering and transferring network.The features of the heat supply network are sparsely distributed heat demand spots, big difference for hot water flow among the branches, very small water flow needed by specific ones, and large excess pressure in some branches. There were only two regulating means, i.e. frequency variation pump and the cutoff valve in the network in original arrangement. Moreover, most of the cutoff valves were opened less than 10%. It was difficult to realize the reasonable heat distribution according to demands under this condition.Based on the real condition in the oilfield, we improve the regulating means by developing of novel throttle elements and applying the self-supported flow regulating valves in the network. A remarkable energy saving effect has been achieved. The control scheme combines the integrated quality (temperature) regulation and local quantity (water flow rate) regulation. The self-control method, proportion control method and friction coefficient method are incorporated into the quantity control scheme. The throttle elements and the self-supported flow regulating valves are newly introduced into the regulating system. Based on the resistance coefficient method, the novel throttle elements are developed from the throttling orifice plate in order to achieve hydraulic balance for branch pipes under the rated flow in the metering station. Compared with the throttling orifice plate, the throttle element, made from metal pipe with small diameter, overcomes the shortcomings of specical manufacturing requirement and unstable resistance in operation, and can be replaced and maintained easily. The pressure drop through the elements varies linearly with the length of the tube, and is proportional to the square of flow rate with constant geometrical parameters. The elements with the same value ofΔP/G2 have the same regulation characteristics even for the different diameter and length and can be interchanged. On the basis of hydraulic balance in the metering station, the self-supported flow regulating valve is introduced as an integrated control method to realize the proportional control. It can control the flow rate to a set value with its pressure drop in the range of 0.05 to 0.6MPa and increases the stability of the heating network. The test results in the oilfield show that the energy saving of 13.8% is achieved each year on average after reconstruction and the capital payback lifetime is less than 4 months. Considering the large error for calorimeter from flow rate and temperatures gauging of supply water and back water individually, the anti-explosion calorimeter with high precision is developed. Additionally, the problems of thermal insulation and overheating of integrated instruments is solved too.
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