r 232 MS5001 Technical Description

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Nuovo Pignone GE Power System - Oil & Gas

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MS5001 GAS TURBINE Technical Description

NP/GE PROPRIETARY INFORMATION

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INTRODUCTION NUOVO PIGNONE is a GENERAL ELECTRIC Company located in Florence (ItalyE U) founded in 1842 and producing gas turbines since early ‘60. NUOVO PIGNONE manufactures a complete line of gas turbine for all major services. They are installed in natural gas plants, gas compression stations, oil booster stations, petrochemical plants, power generation and cogeneration plants all over the world. The MS5000 heavy duty gas turbine is available both in single-shaft and two-shaft versions. The MS5001 (single-shaft version - generator drive) is a compact and reliable prime mover, designed for long life and ease of maintenance. It consists of a 17 stage, high efficiency, axial-flow compressor coupled to a two stage turbine and a combustion system with 10 chambers, able to burn a wide range of fuels, from liquid distillates to all gaseous fuels, including low BTU gas and residuals. It has also a fuel mix burning capability. The design electric output is 26,300 kW base load and 27,830 kW peak load with an heat rate of 12,650 kJ/kWh at ISO conditions (15°C, 60% Relative Humidity, at Sea Level) with 88,9 mm H2O inlet loss and 63,5 mm H2O exhaust loss. It is a very suitable unit for combined cycle and cogeneration plants which can achieve very high fuel utilization indexes allowing considerable fuel savings. The gas turbine package consists of two compartments, one housing the auxiliaries and the other one the gas turbine engine. Both gas turbine and auxiliaries are mounted on a common integral base-plate and have a common ventilation system. The accessory compartment contains the mechanical auxiliaries, both mechanically (via a multi-shafts accessory gear) and electrically driven, the lube oil system, the fuel systems and the gas turbine starting means. The turbine compartment is partially separated from the accessory compartment by the combustion air inlet plenum.

MS5001 GAS TURBINE ENGINE Axial Compressor The MS 5001 gas turbine has a 17 stage axial-flow compressor with two position inlet guide vanes (Custom 450 material). The compressor is constructed of individual rebadded discs (AISI 403) held with through bolts.


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The IGV (inlet guide vanes) and the first two stages of rotor blades and stator vanes are Custom 450 uncoated. From 3 to 7 stages the blades and vanes are AISI 403 GECC1 coated for corrosion protection while the other blades and vanes (8-17 stages) are AISI 403 uncoated. The rotor blades have dovetailed bases of a wide angle design which fit into the matching dovetail openings in the wheels. The stator vanes also have dovetailshaped bases that fit into dovetail shaped openings in two piece, semi-circular ring. Looking keys prevent the rotating of the blade rings The compressor rotor is dynamically balanced before assembling to the pre-balanced turbine rotor components. The whole rotor assembly is then dynamically balanced. Bleed air can be extracted from the 4th and the 10th rotor stages to: - cool the turbine parts subject to high operating temperatures - seal all the turbine bearings - provide atomizing air for liquid fuel (if any) - provide an operating air supply for control valves

Combustion System The MS5001 machine incorporates a reverse flow combustion system consisting of 10 combustion chambers assembly with relevant fuel nozzles, 2 spark plugs and 4 flame detectors. The combustion chambers are arranged concentrically around the axial flow compressor and are bolted to the compressor discharge section bulkhead. Air for combustion is supplied directly from the axial-flow compressor to the combustion chambers. Fuel is fed into the chambers through fuel nozzles that extend into each chamber's liner cap. Combustion of the fuel and air mixture is initiated by retracting electrode type spark plugs. The chambers without spark plugs are fired with flame from the fired chambers through interconnecting crossfire tubes. Cap and liner are Hastelloy X material (nickel based super alloy) while the external shell is carbon steel. The 4 flame detectors are installed in the combustion system to actuate the alarm in case a flame failure occurs. High pressure air coming from the axial compressor is directed around the transition pieces. This encounter affords an heat exchange, cooling the transition pieces and preheating the combustion air. Transition pieces (Hastelloy X material) take the hot gas to the first stage nozzle. The combustion chamber system for MS5001 gas turbine is available in both standard and DLN (Dry Low NOx) versions.

Standard system The standard configuration consists of 10 reverse flow conventional diffusion combustion chambers.


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The fuel is injected by each nozzle with several injection points in order to obtain an optimum distribution of the flame. A dual fuel configuration is available as option. Water or steam injection can be used for NOx emission reduction or, in case of steam injection, for power augmentation.

DLN system (Option) The thermal NOx are generated in the liner in which the temperature is higher than 1800°C. The NOx generation is tightly linked to the temperature and any slight temperature drop involves a significant decrease of the NOx without affecting the combustion efficiency. The DLN (Dry Low NOx) system is based on ‘premix’ combustion chambers which burn ‘lean premixed mixture’ of fuel and air in order to obtain lower firing temperature and therefore lower NOx emissions. Indeed the role of premixing is to obtain an homogenous mixture with an equivalent ratio of 0.7 (1 is the staechiometric ratio). In the conventional mode of combustion with a diffusion flame, fuel is injected into a turbolent mass of burning air and there are regions of wide range of equivalent ratios. The high equivalent ratio regions will lead to high combustion temperature generating high NOx level. It uses staged multi-nozzle combustors with relevant DLN valves. These valves regulate the distribution of fuel delivered to the different nozzles. During normal loading and unloading the system will progress through different stages of operation from diffusion up to the premix steady stage (full load). Outer Combustion Case Assembly

Retractable Spark Plug Combustion Air

Fuel Gas Duel Fuel Nozzle Assembly

Cooling Air

Primary Fuel Nozzle and Combustion Cover Assembly

Venturi Assembly

Flow Sleeve

Combustion Liner Assembly

Wrapper

Flow Sleeve Dilution Air Transition Piece Assembly

Combustion Zone

Liquid Fuel Oil

Cap & Centerbody Assembly Premix Chamber

Cooling Air

Atomizing Air

1st Stage

Secondary Fuel Nozzle Assembly

XFire

2nd Stage

Pilot Cup Sub Pilot

Flow Combustion Case Cover

Crossfire Tube Connection Slot-Cooled Liner Assembly

Transition Piece Transition Piece Transition Piece Compressor Discharge Air

Single Nozzle Combustor


Case, Combustion Outer

Compressor Discharge Casing

Dry Low NOx Combustion System

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Water Injection (Option) The water injection in the liner is made to reduce the temperature in the primary zone. The injection rate (water to fuel ratio) is a function of the requested reduction of the NOx emission level. The water injection affects the gas turbine performances as follows: - Increase in output, - Decrease of the efficiency (increase of the heat rate). The water injection device is associated to each fuel nozzle assembly. On the outer face of the combustion chamber cover, connecting device is arranged to connect each nozzle to the water manifold.

Steam Injection (Option) Also in this case, the injection rate (steam to fuel ratio) is a function of the requested reduction of the NOx emission level. The steam injection affects the gas turbine performances as follows: - Increase in output, - Increase of the efficiency (decrease of the heat rate). The steam injection device is associated to each fuel nozzle assembly. On the outer face of the combustion chamber cover, connecting device is arranged to connect each nozzle to the steam manifold. Unlike injection for NOx reduction, in case of steam injection for power augmentation the steam is injected into the compressor discharge casing.

Turbine The turbine section is provided with a two-stage impulse turbine rotor. The first-stage, or high pressure wheel and the second-stage, or low pressure wheel, are bolted together to make up a single unit. These components, with associated air seal and deflectors, are contained within the turbine shell. Compressor fourth-stage extraction air is piped to cool the shell and then discharged at the aft end of the shell to cool the aft surface of the second stage turbine wheel. The first-stage nozzle assembly (FSX 414 material uncoated) consists of airfoil-shaped partitions between an inner and outer sidewall. The nozzle assembly is divided into segments, with the segments fixed in a retaining ring assembly sustained in the turbine shell by a clamping ring. The nozzle ring and partitions are cooled to reduce metal temperature by compressor discharge air which is bled from the combustion chamber transition space.


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The second-stage nozzle (FSX 414 material uncoated) and diaphragm assembly is located between the first and second-stage turbine wheels. It is supported by a clamping arrangement in the turbine shell. The assembly has airfoil-shaped partitions between the inner and outer sidewall which direct the gas flow into the second-stage turbine buckets. The buckets are designed with long shanks to isolate the turbine wheel rim from the hot gas path. Precision cast buckets are used for each turbine stage with the second stage incorporating an integral tip shroud. First stage buckets are GTD111 with GT29+ coating, second stage buckets are U500. Compressor discharge and extraction air are used to cool the turbine wheels.

Bearings The gas turbine unit has two main bearings, one located in the inlet casing and the other located in the exhaust frame, both support the compressor/turbine rotor. The N. 1 bearing assembly actually contains three bearings; loaded thrust (active), unloaded thrust (non active), and journal. The N. 2 bearing assembly contains only a journal bearing. The bearing assembly consists of oil seal system, an oil ring and the surrounding housing. The main turbine bearings are pressure-lubricated by the lube oil supplied from the lube oil header. The drain oil returns through passages in the bearing housing, then into the drain line to the oil tank. The oil seals control the oil flow along the shaft. The seals consist of labyrinth packing of teeth assembled at the extremities of the bearing assemblies.

Support Frame The forward end of the gas turbine is supported by a flexible plate that is welded to the base and bolted and doweled to the air inlet casing. A rigid leg type support, close-fitted on a support trunnion, is provided on each side of the turbine shell. The supports permit lateral and axial movement due to the thermal expansion.

Gas Turbine Casing The compressor casing encloses the compressor portion of the rotor and is divided into four sections: inlet, forward and aft made of grey cast iron, discharge made of ductile iron. All of these sections are split horizontally to facilitate servicing. The inlet section contains the inlet guide vanes system and the N.1 bearing assembly. Bearing casing is connected to external casing by struts. The loads are then transferred to the baseplate by the anterior mount.


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The turbine casing contains the two stages turbine and the transition piece. It is horizontally splitted. The exhaust casing contains an inner casing which is externally cooled by air coming from the compressor 4th stage. It also supports the rear bearing casing by struts.

Baseplate The unit is mounted on a structural steel baseplate made of two longitudinal H beams connected by other H-beams and sheet plates. The mineral oil tank, which contains the lube oil for gas turbine and driven units, is fabricated as an integral part of the base at its forward end. The mineral oil tank is therefore made of carbon steel with special internal coating. The following components are located on the baseplate: - Load coupling - Starting system - Fuel system - Oil system - Accessory gear with relevant coupling - Inlet plenum - Exhaust diffuser


r 232 MS5001 Technical Description

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