METHOD FOR AUTOMATICALLY MAINTAINING THE TEMPERATURE REGIME OF TECHNOLOGICAL PROCESSES OF LOW-TEMPERATURE GAS SEPARATION INSTALLATION BY TURBO EXPANDING UNIT IN THE CONDITIONS OF NORTH OF RUSSIAN FEDERATION

摘要

FIELD: gas industry. ;SUBSTANCE: invention relates to the field of production and preparation of gas and gas condensate for long-distance transport, in particular to the automatic maintenance of the temperature regime of the technological processes of the low-temperature gas separation installation during the period when the cooling of the extracted gas is carried out by turbo expander units (TEU) in the conditions of the North of the Russian Federation. The method includes preliminary purification of the extracted gas-liquid mixture from mechanical impurities, separation of a mixture of unstable gas condensate (UGC) and an aqueous solution of an inhibitor (ASI) in a separator of the first reduction stage. The partially purified extracted mixture is directed from the output of the separator of the first stage of reduction through the flow control valve (CV) of the extracted gas-condensate mixture and divided into two streams, which are fed for pre-cooling to the input of the first sections of recuperative heat exchangers hereinafter referred to as “gas-gas” “gas-condensate” HE. Both streams, after leaving the first sections of the HE, are combined and fed to the input of the TEU turbine equipped with a rotor speed sensor. Then the cooled extracted gas-liquid mixture is fed into a low-temperature gas separator equipped with a temperature sensor, in which it is finally divided into dried cold gas and a mixture of UGC and ASI. The cold dried gas coming out of the low-temperature separator is divided into two streams. One of them is fed to the input of the second section of the “gas-gas” HE, and the second to the bypass of this section, equipped with a gas flow CV, which changes the flow ratio of these cooled gas flows. Then these gas flows are combined and fed to the input of the TEU compressor. A mixture of UGC and ASI from the lower part of the low-temperature separator is fed to the entrance of the second section of the “gas-condensate” HE and then to the working fluid, from which the separated UGC is sent to the MCP, ASI for regeneration, and the flow of the separated gas, weathering gas from the working fluid is transported for disposal or compressed and fed to the main gas pipeline (MGP). Automatic temperature maintenance in a low-temperature separator is carried out using proportional-integral-differentiating regulators (PID regulators). To obtain the set temperature T in a low-temperature separator, the automated process control system supplies a single value of its setpoint signal to the SP input of the PID controllers that control the operation mode of “gas-gas” or “gas-condensate” HE and the PID controller that determines the setpoint of the required speed of rotation of the TEU rotor, which is required to be maintained. At the same time, the automated process control system sends a signal of the actual temperature T value from the temperature sensor in the low-temperature separator to the PV feedback input of the same PID controllers. The automated control system also sets the order of switching on/off these three PID controllers. The PID controller, which generates the signal of the setpoint of the rotation speed of the TEU rotor, feeds it from its CV output to the input of the SP task of the PID controller, which directly controls the rotation speed of the TEU rotor. ;EFFECT: invention provides the maximum use of the refrigeration produced at the installation for automatic maintenance of the temperature regime in a low-temperature separator in compliance with technological norms and restrictions provided for by its technological regulations. ;5 cl, 2 dwg