Natural Gas Reducing & Metering Stations
The aim of a pressure reducing skid is to regulate the natural gas outlet pressure to a setting value. One typical solution consists mainly of two reducing lines (2×100% capacity) with two regulators each: one main regulator and the other is used as a monitor/slam shut valve. Both regulators are “top entry type” in order to guarantee simple equipment maintenance. The active regulator normally assures pressure reduction to the setting value. In the event of an accidental increase of outlet pressure, the second monitor regulator will take over as a control valve.
During normal operation, one line is working while the other line is in stand-by. The stand-by line only starts to work in case of failure of the monitor and main regulator. In the event outlet pressure exceeds an acceptable value a slam shut device protects the equipment downstream of the pressure regulators from over-pressure.
To minimize accidental intervention of the slam-shut device, a spring-loaded pressure relief valve is installed and designed to release relatively small quantities of gas only.
Natural Gas Odorization Stations
Pietro Fiorentini odorant injection systems can manage different types of odorant, such as TBM and THT, and guarantee a constant odorization ratio at every gas flow rate. Depending on system requirements, injection may occur either by means of solenoid valves or by a volumetric pump.
In the case of solenoid-driven systems, a connection with the high-pressure section of the plant delivers the required pressure to inject the odorant into the gas line. Regulation of odorant quantity is obtained with micrometric valves and opening time of the solenoid valve.
All systems are provided with a dedicated control unit to manage process parameters, acquire the signals from the metering equipment in the plant, and adjust the amount of odorant injected based on gas flow.
In pump systems, the pump delivers the required pressure to inject the odorant into the gas line. The minimum quantity of odorant injected can be set by tuning the stroke of the pump.
The odorant storage tank can be used also as backup system in case of system failure. Part of the gas is sent through the storage tank and, by lapping the surface of odorant, the gas takes away a quantity of odorant into the main stream.