Condensate return pumps are used to move water from the main condenser hotwell through several intermediate components (such as the condenser gland steam system and the ejector air removal system) back into the boiler feedwater system.  Seemingly a relatively simple and straightforward application, condensate return pumps must in fact be carefully specified to consider factors such as wide variations in turn down and very low NPSH requirements, and the need to integrate with the hotwell level control system. MVT offers a line of custom designed condensate pump systems in duplex, triplex, and quadruplex configurations to meet these requirements. We work closely with a few select pump suppliers to design a system that will work automatically to maintain proper level in the hotwell under varying load conditions.  These are ‘plug & play’ packages that include isolation valves, non-return valves, vibration isolators, by-pass control valves (when needed), manifolds, and instrumentation for a complete, engineered solution.  Options include control panels with logics, motor starters, and level control instrumentation for remote monitoring and control.

Key features and benefits of our condensate pump systems for the plant are:

• Full range of capacities available for any main condenser requirement.
• Careful matching of pump performance with level control requirements.
• Compliance with typical industry standards such as ASME, ANSI, PED, CRN, etc.
• Innovative package designs, with ‘single point’ customer connections for all process and utility requirements.
• Control system integration with hotwell level controller.
• Typical Power Industry quality component suppliers, with ASME code qualified welding throughout.
• Comprehensive field service and support program.
• Industry leading 3 year warranty.

The term ‘Hybrid’ can mean several different design concepts when applied to air removal systems.  In recent years, particularly when used in association with cogeneration and solar thermal plants, it refers to using liquid ring vacuum pumps for hogging duty, and steam jet ejectors for holding duty.  The opposite is also done, although much less frequently.  This approach is used to obtain the best advantages of both; using pumps for hogging when start-up steam is often not available, and using ejectors for holding to avoid potential cavitation concerns with partial load – low absolute pressure operation with pumps.  While they service the same condenser, they are independent systems, with only one system operating at a time as required.

A true hybrid air removal system consists of a first stage ejector, an intercondenser, and a liquid ring vacuum pump (typically two stage) on the same skid.  The pump does hogging duty, and operates as the final stage of the system during holding operation.  The ejector serves as a booster for the pump, increasing the inlet pressure so that the pump will never operate at or near cavitation conditions.

This design takes advantage of the operating characteristics of both components in a compact, cost efficient package.   Key advantages of this concept are low steam usage, modest parasitic pump power requirements (compared to vacuum pump exhausters), the ability to use closed cycle cooling water for the pump(s), and fully automatic operation consistent with the demands of today’s power plants.

MVT Hybrid Exhausters offer the plant a venting system to cover a very wide range of condenser performance requirements, in an efficient, cost effective package.

Key features and benefits of our hybrid systems are:

• Full range of capacities available for any main condenser requirement.
• Comprehensive F.A.T. (factory testing) to insure proper operation at the plant.
• Compliance with typical industry standards such as HEI, ASME, ANSI, PED, CRN, etc.
• Innovative package designs, with ‘single point’ customer connections for all process and utility requirements.
• Typical Power Industry quality component suppliers, with ASME code qualified welding throughout.
• Comprehensive field service and support program.
• Industry leading 3 year warranty.

Power plants that use natural water sources for cooling often require the main condenser water boxes to be primed to reduce circ water pump horsepower, and to remove air that comes out of solution as the water heats up going through the tubes, tending to accumulate in the top of the water boxes with negative consequences to condenser performance.

A typical waterbox priming system consists of two liquid ring vacuum pumps mounted on a vacuum control tank which serves to modulate cycling of the pumps during continuous air removal duty.  Both pumps are sized to prime the condenser tubeside and lift circ water to the top of the waterboxes before the circ water pumps are started.  Once initial prime is obtained, the system automatically goes into ‘normal’ service, where vacuum in the control tank is maintained by alternating pump operation as air is removed from the top of the waterboxes.  Priming valves mounted on the top of each waterbox release air while preventing circ water from getting into the priming system. MVT offers a complete line of tank mounted duplex waterbox priming systems designed for typical modern combined cycle condenser installations.

We provide custom designed systems for larger condensers and unusual installation requirements.  Each system is complete with automatic controls for local and/or remote operation.  We also provide priming valves (suitable for seawater service) and all required accessories.  Options are available for air cooling where a convenient source of cooling water is not available and complete control systems with motor starters for remote installation locations.

Key features and benefits of MVT waterbox priming systems are:

• Full range of capacities available for any main condenser priming requirement.
• Comprehensive F.A.T. (factory testing) to insure proper operation at the plant.
• Compliance with typical industry standards such as ASME, ANSI, PED, CRN, etc.
• Innovative package designs, with single point customer connections for all process and utility requirements.
• Comprehensive instrumentation suite for DCS monitoring of system performance.
• Rugged designs with material suitable for raw water and seawater service.
• Typical Power Industry quality component suppliers, with ASME code qualified welding throughout.
• Comprehensive field service and support program.
• Industry leading 3 year warranty.

Using liquid ring vacuum pumps for condenser air removal is not just another application when it comes to pump sizing and system design.  Requirements such as frequent start/stop operation, wide ranging inlet conditions and cooling water temperatures, frequent low absolute pressure operation with cavitation potential, and very high reliability and low maintenance needs impose demands on the pump system design that few in the ‘liquid ring world’ appreciate.

MVT liquid ring exhausters are designed for the real world of today’s power plant requirements.

Two independent 100% capacity two stage pump systems are typical, with both operating in hogging mode to evacuate the condenser to the point where the steam turbine is started, then under the control of the DCS one pump shuts down and the other automatically goes into holding mode for continuous air removal duty.   Control of the hydraulics around the pump is key to proper holding operation, so that the pump provides the required dry air capacity without cavitation at any point on the condenser thermal curve.

Today’s power plants are designed to be highly automated, with reduced operations and maintenance staff’s compared to historical norms.  MVT exhausters are designed for this environment with DCS remote control standard, and a comprehensive suite of instrumentation to provide critical operating data to the DCS.  This information is readily available for use by MVT engineers to assist the operators with system diagnostics and troubleshooting in real time.   Immediate help is a phone call away!

Every MVT exhauster provides the plant with these features and benefits: 

• Full range of capacities available for any main condenser requirement.
• Comprehensive F.A.T. (factory testing) to insure proper operation at the plant.
• Compliance with typical industry standards such as HEI, ASME, ANSI, PED, CRN , etc.
• Innovative package designs, with single point customer connections for all process and utility requirements.
• Typical Power Industry quality component suppliers, with ASME code qualified welding throughout.
• Comprehensive field service and support program.
• Industry leading 3 year warranty.

Steam ejectors have been the mainstay of condenser air removal service for many years.  The design of ejector systems during the 60’s and 70’s were based on the needs of the base load thermal plants built during that era, which operated 24/7 around a very narrow range of performance, with only seasonal variations in cooling water temperatures impacting the range of expected performance.

Today’s combined cycle, cogeneration, and solar thermal plants impose a very demanding range of performance parameters on the ejector system to match the highly variable operation requirements of these plants, with daily start/stop cycles and partial steam turbine loads, in addition to normal seasonal changes. MVT ejector air removal systems are designed to meet these requirements, with wide range dry air performance at the design capacity criteria for the plant, insuring that the system will have full HEI® venting capacity at all points on the condenser thermal curve, with consideration for wide ranging condensate flows and temperatures.  This design philosophy is especially important for the venting requirements of Air Cooled main condensers.

At MVT, we thoroughly understand the design and operating requirements of ejector systems for this demanding application.  In addition to the typical requirements for wet surface condensers, ACC’s impose even wider operating ranges on the venting system.  The system must designed for both wide range two stage and single stage performance.

• Full range of capacities available for any main condenser requirement.
• Compliance with typical industry standards such as HEI, ASME, ANSI, PED, CRN , etc.
• Manual and fully automatic operation (pneumatic or motorized), with control logics locally integrated or DCS remote control.
• Innovative package designs, with single point customer connections for all process and utility requirements.
• Typical Power Industry quality component suppliers, with ASME code qualified welding throughout.
• Comprehensive field service and support program.
• Industry leading 3 year warranty.