Double-valve control system and method applied to supercritical carbon dioxide turbine

Abstract

The invention discloses a double-valve control system and method applied to a supercritical carbon dioxide turbine, and aims to reduce the preheating time of dry gas seal intake and a dry gas seal shell, reduce the influence of airflow in the turbine on a rotor when the turbine is started at a low speed, and maintain the stability of axial force of the rotor during emergency shutdown. The upstream end of the dry gas seal gas inlet chamber is connected with a dry gas seal gas inlet valve, the carbon ring emptying pipeline is communicated with the cooling gas chamber, the turbine emptying pipeline is communicated with the exhaust cavity, the downstream end of the carbon ring emptying pipeline is connected with a carbon ring protection valve, the downstream end of the turbine emptying pipeline is connected with a turbine emptying valve, and the turbine emptying pipeline is communicated with the turbine emptying valve. The upstream end of the air inlet cavity is connected with a regulating valve, and the downstream end of the exhaust cavity is connected with a shut-off valve.

Description

technical field [0001] The invention relates to the technical field of supercritical carbon dioxide turbines, in particular to a dual-valve control system and method applied to supercritical carbon dioxide turbines. Background technique [0002] The cycle power generation system using supercritical carbon dioxide as the medium has high efficiency, can replace the traditional power generation cycle system, and the system is small in size. Its pressure is high, and traditional seals such as sparse teeth can no longer meet the requirements of use; in order to better seal the unit and improve the efficiency of the unit, the dry gas seal is generally selected as the sealing component for the supercritical carbon dioxide turbine seal. [0003] The supercritical carbon dioxide turbine medium is supercritical carbon dioxide. In this state, the density of carbon dioxide is high, close to liquid, but its fluidity is similar to that of gas, and its chemical properties are stable and ch...

AI Technical Summary

Problems solved by technology

Carbon dioxide will form liquid or even solid under low temperature and high pressure. If the temperature and pressure are not well controlled, it will damage the dry gas seal. After the temperature rises to a safe value, the cranking can be started and the turbine can be turned; however, during the temperature preheating process, the preheating pressure of the dry gas seal should not be too high at the beginning (low temperature, high pressure seal gas will form a liquid or solid), the damping of the sealing gas passing through the turbine unit is large, so the flow rate of the dry gas seal is very small at first, and the temperature of the dry gas sealing gas will be further reduced under the influence of valves, carbon ring seals and other components, so that Firstly, it will take a long time for the dry gas to seal the air intake and the shell to warm up, which will bring different degrees of losses to the enterprise; when the turbine is cranked, due to the low speed of the turbine, the formation of oil film on the rotor and bearing is still unstable , and when the speed is low, the bearing capacity of the thrust bearing is also low. In order to minimize the influence of the air flow on the rotor, it is necessary to ensure the stability of the air flow inside the turbine; when the turbine is shut down in an emergency, the inlet and outlet valves of the turbine are closed instantly. The positive flow of the turbine airflow is prevented. Since the carbon ring seal gap is small and the damping is large, it takes a certain amount of time to establish a pressure balance before and after the carbon ring seal. The dry gas seal gas is always introduced, and the pressure difference before and after the carbon ring seal will be instantaneous. increase, the rotor is likely to generate a large axial force at this time, resulting in axial movement of the rotor and damage to the unit

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