View source for Amine Charge Pumps(P-1102A/B)

Inside the process pump building, the cooled flow from the lean amine cooler is drawn into the suction of the online Charge pump.

<u>'''Note:'''</u> 
The amine process has two charge pumps:
*one charge pump is normally in service
*the standby charge pump is available to provide the process when the primary pump is not available. The standby charge pump is then valved to serve the process; the pump is not operated to simultaneously supply lean amine with the other pump.


=Purpose and Operation=

Each charge pump is a 3 stage centrifugal pump driven by a back pressure steam turbine. The purpose of the online charge pump is to supply high pressure amine to the A and B Amine contactors so that both contactors can sweeten raw gas (figure 7). The pump increases amine pressure as required by the high pressure raw gas sweetening conditions in the Contactors.

The charge pump pressurizes the lean amine flow as follows:
*the lean amine arrives at a pressure of approximately 75 psig since the lean amine was partially pressurized by the Booster Pump but has lost some pressure while flowing through the lean amine cooler/piping
*the charge pump discharges the amine at a pressure of approximately 1371 psig, which is above the gas pressure so it can push into the contactors.

[[File:ChargePumps.png|center|frame|Lean Amine High Pressure Charge Pumps]]


=Local Valving=

The two charge pumps are arranged east to west as follows:


===Charge Pump’s Valving===

At the charge pump:
*lean amine flows through the pump’s open manual suction block valve
*the flow is then drawn into the pump and discharged past the pump’s minimum flow control valve, this valve ensures that minimum flow through the pump is always maintained. The minimum flow control valve discharges back to the amine surge tank
*deadhead prevention role—when the pump’s discharge flowpath is closed or restricted, the valve’s bypass passage diverts amine via a recirculation flowline to the amine surge tank. The pump recirculates at a minimum flow-rate to prevent deadhead damage. Because of the deadhead protection role of the minimum flow control valve, the recirculation flowline must not be inadvertently isolated. During a pump switch the Area Operator must ensure that the recirculation valve is open to the amine surge tank.
*after the minimum flow control valve, the lean amine flow passes through the pump’s normally open manual discharge block valve and continues downstream to branch into the separate flows that supply the A and B Contactors (see Figure 7).

The charge pump is also equipped with manual drain/bleed valving.

=Shaft Bearing Lubrication and Seals=

===Bearing Lubrication===

Each charge pump is equipped with sleeve type inboard and outboard bearings. Each bearing receives lubrication oil from the steam turbine’s lube oil system (figure 8).

===Pump Shaft Seals===

The charge pumps has two seal monitoring system (figure 8), that is a contained reservoir system complete with level and pressure transmitter connected to the pump bearing housing.
*The level transmitters, connected to the DCS, have configured alarms inboard bearing (LAH-2153) and outboard bearing (LAH-2613)
*The pressure transmitter, connected to the DCS, have configured alarms inboard bearing (PAH-2152) and outboard bearing (PAH-2612)

Seepage of the bearing shell will increase the level and pressure in the reservoir therefore triggering an alarm. A total seal failure, results in an immediate increase in reservoir pressure and level, and an immediate shutdown, inboard bearing (PAHH-2152) and outboard bearing (PAHH-2612) causing a shutdown.

[[File:CPLubeandSeals.png|center|frame|Charge Pump Lubrication Flows and Seals]]


=Steam Turbine Driver=

===Operation===

Both charge pumps are driven by individual single-stage steam turbines. Each turbine has:
*a governor valve that modulates the steam flow through the turbine in response to the turbine’s governor. The turbine maintains speed by matching the setpoint entered to automatically control the speed by adjusting the governor valve.
*an overspeed trip valve which is triggered to close in case of steam turbine overspeed
*the following bearing/seal configuration:
:-an outboard journal bearing and thrust bearing
:-an inboard journal bearing
:-carbon ring seals at the turbine shaft at either end of the casing which tie into a backpressure control valve (PCV-2509) and then flows into a condenser (HT-1117A) . The condenser is a small shell and tube condenser that uses glycol as the cooling medium to condense the Gland steam (refer to common equipment module). After if flows through the condenser it flows through a small condensing pot and into the LP condensate header.
*manual casing drains and steam chest drains to drain condensate during prestart turbine warm up
*free-flowing leak-off lines to drain condensate/passing steam from turbine components continuously during turbine operation

As described for the booster pumps, the steam turbine operates in a backpressure configuration where the turbine uses 570# steam and exhausts 70# steam. Steam flows from the 570# steam header (see Module 3— Utilities) to supply the charge pump’s steam turbine:
*steam flows from the 570# header through a manual steam header isolation valve
*the steam then flows through the turbine’s 570# inlet block valve to the turbine
The steam flowpath through the turbine is as follows:
*the steam flows through the governor valve
*the steam enters the turbine through an overspeed trip valve,
*the steam then flows through the turbine; steam expansion drives the pump

Steam discharged from the turbine flows to the 70# steam system:
*the steam discharges from the turbine and flows past a Pressure Relief Valve (PRV-2171) equipped draw-off. The PRV is set to open to atmosphere at 85 psig to relieve overpressure
*after the PRV-equipped draw-off, the steam flows through the turbine’s 12” outlet block valve and flows into the LP steam header

===Drain and Leak-off Lines===

Draining condensate from a steam turbine that forms during prestart warming is an operating precaution; no water must be in the turbine during operation because water impact against the high speed blades can result in destructive turbine failure.

Each steam turbine is equipped with casing drains and steam chest drains. The casing/ steam chest drain lines are equipped with manual drain valves to vent steam to atmosphere and drain condensate to the sewer via a collection header while warming up the turbine. After warmup, the drains valves can be closed, but ensure that the steam trap-equipped drain lines are not isolated.

Leak-off lines drain condensate/passing steam from turbine components continuously during turbine operation to ensure that pressure does not build up on the non-steam side. The steam turbine has leak-off lines from the casing which continuously flows to the LP header.

===Lubrication System===

The pressure lubrication system that supplies lube oil (figure 8) to the steam turbine bearings is configured as follows:
*oil is stored in a reservoir tank. The oil reservoir is equipped with:
:-a sight glass to monitor oil level in the tank
:-an oil filler cap
*a shaft-driven oil pump draws oil from the turbine’s oil reservoir tank.
*Or an Aux oil pump for turbine startups
*the cooled oil then passes through an oil filter. The oil filter has a local indication to determine if the filter should be removed from service and switched to standby.
*the cooled oil then passes a drawoff equipped with a Pressure Relief Valve (PRV-2171). At 10 psig, the PRV relieves overpressure oil back to the oil reservoir.
*the filtered oil passes through an oil cooler. The oil cooler is a shell-tube heat exchanger uses a tubeside glycol coolant to cool shellside oil.
*after the PSV drawoff, the oil branches to supply:
:-the turbine’s inboard/outboard bearings
:-the low oil pressure trip device known as the oil plunger

After providing turbine bearing lubrication, the oil returns to the oil reservoir to be recirculated.

The pressure lubrication system has the following instrumentation:
*A temperature control Valve (TCV-2169) that controls the flow of oil to maintain the proper temperature
*temperature transmitter (TIT-2167) that display the temperature downstream of the oil cooler locally and on the DCS
*a pressure indicator (P-1115A) that shows the oil supply pressure discharging from the Shaft driven pump
*a pressure indicator (P-1116A) that shows the oil supply pressure discharging from the Aux oil pump
*a differential pressure indicator across the oil filters (PDI-2166)


=Flow and Speed Control=

To sufficiently meet the gas sweetening requirements in the contactors, 1391 USGPM of lean amine is discharged from the online amine charge pump.

The steam driven amine charge pump has the following features:
*A woodward peak 150 governor controls the speed of the turbine. The turbine maintains a speed matching the setpoint entered locally in the peak 150 governor control system, by automatically controlling the governing speed control valve (FV-2521)
*an overspeed trip valve (SV-2518), which is triggered to close in case of steam turbine overspeed

A secondary overspeed trip sensor is also installed and will activate a trip if the primary mechanical trip fails to activate a shutdown.

<u>'''Note:'''</u> The specific lean amine flow setpoints for raw gas sweetening and off gas sweetening are determined by the CRO. In general, more lean amine is required under the following conditions:
*H2S concentrations have increased
*a higher sour gas flowrate must be sweetened
*the amine strength has declined


=Instrumentation, Alarms and Shutdowns=

The charge pump has the following instrumentation, alarms, and shutdowns:
*on the lean amine feed line to the A and B Contactors, orifice flowmeters (FE-2162) and Flow transmitters (FIT-2161) on the lean amine outlet:
:-provide onscreen flow indication in the control room
:-Control the flow of the minimum flow control valve (FY-2161) which ensures there is always flow through the charge pumps
*the suction line to the pump has a pressure transmitter that:
:-provides onscreen suction pressure indication at DCS
:-triggers a Train shutdown to protect against cavitation/dry running if the pressure drops to 60 psi
*local control panel that displays pump speed and flow
*pressure gauges provide local indication of the pump’s suction and discharge pressures
*shaft speed indicator with indication on DCS

The charge pump’s steam turbine has the following instrumentation, alarms, and shutdowns:
*a flowmeter on the 570# steam supply line to the turbine provides onscreen flow indication at DCS
*an overspeed trip
*local oil pressure and oil filter differential pressure indication
*local inlet and outlet oil temperature indication

The Standby and Charge Pumps have similar instrumentation, alarms, and shutdown as described above for the Charge Pump.

=Specialty Lines and Valve=

The two Charge Pumps are equipped with a Minimum Flow control valve. The valve ensures that there is always a minimum flow maintained through pump at all times. The controlled flow of amine is diverted back to the Amine Surge Tank.


=Operations Monitoring=

===Monitoring Pumps===

At the online Charge pump, the Area Operator:
*checks local pump pressure gauges to ensure:
:-the pump suction pressure is 76 psig. The specific pressure varies greatly as pump flow is increased or decreased but the pressure should remain steady. Pressure fluctuations are an indication that the governor may need tuning or repair
:-the pump discharge pressure is 1291 psig (i.e. train pressure)
*checks the pump for unusual operating noise, excessive vibration, and abnormal operating temperature
*checks that oil is visible in the pump oil cups and tops up as required
*ensures cooling medium is circulating to the pump’s bearing housings
*checks the pump seal flush system and seals to ensure seal problems are identified early
*checks for excessive oil from bearing housing


===Monitoring Steam Turbines===

At the steam turbine driving the online Charge pump, the Area Operator:
*ensures that the reset levers are properly latched for the overspeed trip valve
*ensures that the low oil pressure trip device swing lever is in the down position
*checks turbine lube oil system:
:-confirms lube oil pressures (approx 40 – 60 psig at the lube oil pump outlet and 10 – 15 psig at the bearings
:-checks level in oil reservoir and tops up oil as required
:-confirms that the oil leaving the bearing housings is 120 – 140°F
:-drains lube oil reservoirs to check for accumulated water (as described previously)
*checks turbine for abnormal vibration


===Standby Pump Configuration===

The steam turbine-driven standby charge pump is not normally in service; the pump is offline as a standby. The Area Operator checks the standby status of the standby charge pump and its steam turbine as follows:
*the steam turbine is kept cold when not in use; it is FNNPF practice not to leave the steam turbine on hot standby and valves checked to ensure that amine is not passing through the standby pump.


===Responding to a Charge Pump Trip===

If the online Charge Pump serving (or its drivers) trip, Train 1 is rapidly impacted. An urgent response and close cooperation between the CRO and Area Operator are required to minimize escalating impacts to the FNNPF, upstream producers, and downstream Spectra Energy Gas Transmission line operations.

If the Charge pump (or its drivers) trip, the CRO begins a wide-ranging assessment to minimize the impact on the FNNPF and ensure prompt restoration of Charge amine flow. During this time, the 
Area Operator must be ready to respond to prompt CRO requests regarding. This may include locally investigating the tripped charge pump (and its drivers) to determine if prompt restart is possible or placing the standby charge pump online.

<u>'''Note:'''</u> startup of a charge pump is an integrated, sequenced task directed by the CRO to minimize train startup delays. FNNPF operating procedures describe the coordinated role of the CRO and Area Operator in starting a charge pump and its drivers.