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PANORAMA 3 In many cases, a single-stage HPRT is used to capture the process stream energy and drive a multistage pump. 4 Typical HPRT test setup in a closed loop. Electric Power Supply Electric Power Grid Electrical Power Measurement Pump discharge pressure Pl Throttle valve Turbine inlet pressure can be between 140% and 200% of the nominal speed, depending on the specific speed and the rated conditions. This condition should be taken into account for generator operation and in the selection of the trip device that operates at transient conditions. If the HPRT is used to drive a generator, it may be prudent to use a gear reducer and drive the generator at four- or sixpole (1500 RPM or 1000 RPM at 50 Hz power frequency, 1800 RPM or 1200 RPM at 60Hz power frequency) speeds but mechanically design the generator rotor for two-pole speed (3000 RPM at 50 Hz, 3600 RPM at 60Hz). Motor Pl Pl Electrical Power Measurement Booster Pump Turbine Generator P Pump suction pressure Suction valve Turbine outlet pressure 28 | Sulzer Technical Review 1/2011 Vacuum Pump Flow meter (Venturi or magnetic) Suppression Tank Flow Fluid temperature Air pressure supply Vent Fill Drain Back pressure valve Hydropower turbines have flow control devices, such as wicket gates, which help to avoid high pressure surge during transient conditions. In process HPRT applications, the turbine bypass is always slightly open and is quickly adjusted to maintain inlet vessel level control when the turbine inlet valve trips. Operating with two-phase flow Care must be taken when starting up an HPRT. When an HPRT is driving a generator, it is normally spun-up to near operating speed, and then as the speed nears synchronous speed, the generator is switched to the power grid, which provides a load. Without load, the HPRT may quickly overspeed. Process control is important when applying HPRTs. If the pressure in the exhaust vessel is lowered by 20%, head across the turbine increases, and it will generate 20% more power than at the rated flow and head. For that reason, it is often prudent to oversize the HPRTs, shaft torque capacity to take into account various system upsets in pressure control. Processes have to be started before the HPRT can be brought on stream. Often, there will be a full-size pump with motor driver to get the process started and a parallel HPRT clutch motor pump that is used during normal operation 5 6. For processes with entrained gas or vapor (natural gas treating, fertilizer plants, hydrotreaters, etc.), a small volume percent of gas at the high-pressure side will turn into a measurable volume at the low-pressure side. This gas volume at the outlet may influence the size of the HPRT. The high gas volume in the exhaust may not be an issue if the shaft is robust, the runner is made of cavitation-resistant materials, and the wear parts are hardened to reduce contact damage. However, gas bubbles in the seal chamber will surely do damage to the mechanical seals. Dual seals within Plan 53 or 54 are therefore recommended for process HPRTs to assure that the mechanical seals operate in a controlled, liquid state. Application in hydrocarbon processing A large Brazilian oil company is using pumps as turbines instead of throttle valves and is thus recovering energy. In one case, liquid charged with gas must be expanded in a scrubbing tower. Sulzer worked with oil company engineers to understand the multiphase flow. That knowledge was then used to design the HPRT’s runner and rotor. The experience of Sulzer Pumps in designing such HPRTs helped to find a solution for these challenging conditions. Between the inlet and outlet of a turbine, the pressure drops in very short time. Gas dissolved in the fluid at high pressure diffuses out of the liquid causing gas bubbles to form, resulting in twophase flow. The required pressure reduction is from 74.8 bar (1080 psi) to 14.8bar (210psi). A five-stage HPRT with one dummy stage was chosen, so that a further stage may be fitted for smaller flow rates in the future 7. The continuous power of 258 kW recovered from the expansion assists the 870-kW motor driving the pressure increasing pump. A pump running as a turbine is difficult 5 HPRT equipment layout: Driving the generator at reduced speed can save it on overspeed caused by a sudden power loss. Pump HPRT Gear reducer Motor Clutch Generator HPRT
6 Some HPRT trains are so long that the baseplate is split at one coupling to facilitate shipping, lifting, and installation. Setup: HT-MSD – clutch – motor (missing) – MSD pump. to regulate. Depending upon the pressure drop and application, an HPRT flow rate may be established amounting to 80%–90% of the effective throughput. The remaining 10%–20% of the flow is expanded via a bypass valve and is used to control the vessel level supplying the HPRT. During plant startup, the turbine cannot perform work and may actually 8 Gas plant: MSD pump – motor – clutch – HST turbine. consume energy. If the motor must be used for startup, an overrunning clutch prevents the motor from having to put additional energy into the turbine during this phase. Once the hydraulic energy at the inlet to the HPRT is sufficient, the turbine runs up to the motor speed. The overrunning clutch now ensures that the HPRT cannot run faster and supplies its hydraulic energy to the drive train. Amine contactor Startup pump Level controller Sour gas Startup motor Sweet gas stream Pump Motor Bypass Lean amine stream 7 A gas-scrubbing HPRT application can recover more than 2 MW. Clutch Short payback times In many industrial processes, hydraulic power recovery turbines (HPRTs 8 ) can provide substantial savings with a short payback period. It is not uncommon to find that over 1.5MW can be re - covered. Careful attention to process conditions and HPRT controls assures reliable, useful operation for years of service. HPRT PANORAMA Stripper Ron Adams Sulzer Pumps 800 Koomey Road Brookshire, TX 77423 USA Phone +1 281 934 6029 ron.adams@sulzer.com John Parker Sulzer Pumps 800 Koomey Road Brookshire, TX 77423 USA Phone +1 281 934 6011 johns.parker@sulzer.com Sulzer Technical Review 1/2011 | 29
Page 1 and 2: 1/2011 Proven quality Innovation th
Page 3 and 4: Testing and quality Panorama 4 News
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Page 7 and 8: year, the test setup needs to be st
Page 9 and 10: ment as a function of suction press
Page 11 and 12: teristics such as apparent density,
Page 13 and 14: Nevertheless, a global approach is
Page 15 and 16: Acceleration (g) 40 30 20 10 0 -10
Page 17 and 18: SULZER ANALOGY Testing poisons In t
Page 19 and 20: A product development process at Su
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Page 25 and 26: SULZER INNOVATION The ideal solutio
Page 27: approximately to that of the pump,
Page 31 and 32: distribution remains constant. On t
Page 33 and 34: SULZER WORLD Welcome to Sulzer Pump
Page 35 and 36: anches serve niche markets and, the

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