مهندس بترول1 METHANOL INJECTION SYSTEM
1.1 Normal Operations
The methanol injection pumps have been designed to operate on all the strings upstream each wellhead wing valve (WV) in order to avoid hydrate formation during start up condition when the gas pressure expands from the static pressure to the operating pressure after nitrogen purging operation (estimated 5 bar g).
Moreover, the hydrate formation can occur in the sealine to A/Q PI during the winter season, on the basis of the minimum sea water temperature of 17°C and an hydrate formation temperature of 18,9°C @ 112 barg. Consequently, the methanol injection has been foreseen into the sealine inlet.
In normal operation only methanol injection in to sealine is operative.
Warning 1: During normal operation, all manual valves installed on discharge lines of PSV and pump heads MUST be kept in open position, and consequently is the operating personnel full responsibility to check their position. If, for system components maintenance requirements, it is necessary to intervene on one of the above mentioned valves, this operation can be done ONLY after the total system shutdown.
Since methanol is a toxic and flammable liquid during maintenance operation (planned or extraordinary) the operators shall be equipped with personnel safety devices.
Warning 2: During maintenance, operation of the unit the operator shall dilute the methanol with water up to 3% of methanol in order to make it not hazardous. The filling of the water in the storage tank will be performed by line 3”-CM-001-A1-EP.
While operating, the pump works at a pressure between 114 and 266 barg and a temperature of 30°C.
On the suction pipe, a calibration pot measures and controls the pump flow rate.
The Local Control Panel EUB-000-3-1 detects if the pump is correctly running, injecting methanol at the expected Pressure and Temperature and with a predicted flow rate for each pumping head of 30l/h.
The maximum injection pressure at well head is 266 barg: the Pressure Safety Valves automatically relieve pressure in excess, according to the set value, in each pump string.