ABSTRACT

This is a report of the experience got from the visit to Industry – Notore Chemical Industries, Onne, PortHarcourt. It narrowed down on the electrical Actuator used in their Gas Turbine for the generation of power. Notore Power, a wholly owned subsidiary of Notore Chemical Industries, is an indigenous Independent Power Producer (IPP). Incorporated in August 2007, Notore Power was initially established to generate power for its parent company and maximize the full earning potential of the Notore Group. Notore Power now has the mandate to benefit from the recent power sector reform in Nigeria which has given privately owned power generating companies license to generate, distribute and supply power; a profitable advantage that hitherto belonged to Power Holding Company of Nigeria(PHCN).

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CHAPTER ONEINTRODUCTION Notore Power generates and supplies electricity directly to Notore Chemical Industries and has recently signed a Power Purchase Agreement (PPA) to provide power to high capacity users in the Onne Oil & Gas Free Zone (OGFZ). There are also ongoing plans to sign a PPA with PHCN with a view to supplying power to the National Grid. Notore Power currently has an installed capacity of 50MW. Having successfully obtained a generation license for its operations, plans are currently in place to export power to the Oil and Gas Free Zone in Onne. Although business transactions similar to the Onne Oil & Gas Free Trade Zone and Notore Power agreement are taking place in several industrial zones across Nigeria, we recognize that PHCN remains the largest producer of power in the country. With the chronic lack of power in Nigeria as our motivation, Notore Power has identified a good opportunity to become one of the country’s largest power generating companies. We are well positioned to achieve our vision based on our solid gas infrastructure, secure access to gas, abundance of land, technical expertise and proximity to the national grid. Step by step it is etching its footprint into Nigeria’s re-emerging power sector.

COMPANY PROFILE

Notore Chemical Industries Limited (Notore) is an agro-allied and chemical company owned by a consortium of private and foreign institutional investors. We are championing the African Green Revolution by supporting local food production on the continent thereby creating economic wealth.

In our bid to assist Nigeria achieve her food security goal, we provide a package of the best agricultural products and practices to farmers. This package includes the supply of premium fertilisers, appropriate education on best practices for farming and proper deployment of these resources for optimum results.

Notore was established in August 2005 after the acquisition of the liquidated assets of National Fertiliser Company of Nigeria (NAFCON) by the Bureau of Public Enterprises (BPE). In 2008, we began an extensive rehabilitation of the

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fertiliser plant located in Onne, Rivers State. Upon completion of the project, we commenced production of ammonia and urea in January and July 2009 respectively.

Currently, the Notore fertiliser plant is the only urea fertiliser plant in Sub-Saharan Africa thus making Notore perfectly positioned to become Africa’s major fertiliser supplier. By making fertiliser more available to farmers, Notore is helping to reduce hunger and increase food security on the continent. With the coming of Notore, the African Green Revolution has truly begun.

COMPANY HISTORY

1981: National Fertiliser Company of Nigeria (NAFCON) is incorporated as a joint venture between Federal Government of Nigeria (FGN) (70%) and Kellogg Brown and Root (KBR)(30%)

1987: Plant commences the production of fertiliser and is subsequently officially commissioned with a design capacity of 1,500 MT/d of urea

1996: NAFCON goes into decline

1999: NAFCON is shut down following key equipment failure

2005: A group of investors acquire the assets of an abandoned Government 500,000 MT Urea Plant for $152M USD in an asset purchase transaction as part of Bureau of Public Enterprises (BPE) privatization of hitherto public enterprises

2006: Notore signed Gas Supply Contract for 20 years with Nigerian Gas Company (NGC)

2007: Notore raises a record $222M USD facility from a syndicate of Nigerian Banks

2008: Dredging of the private jetty is completed and the first Ship arrives at the Notore Jetty

2009: Production of ammonia commences in JanuaryProduction of urea commences in JulyNotore and Taraba sign MOU for the establishment of a Rice Mill.Notore and Cross River sign MOU for the establishment of a Rice Mill

LEADERSHIP

BOARD

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HEADS OF DEPARTMENT

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CHAPTER TWO

HISTORICAL BACKGROUND

Most power plants use natural gas, oil or nuclear reactor to creat steam. The steam run through a huge and very carefully designed multistage turbine to spin an output shaft that drive the plant’s generator. The world is the developing in a fast pace that turbines are now designed for power generation, pressure generators, floating vessels, train, ship etc. Gas Turbine is the cheapest and easy to maintain among all types ion Nigeria.

A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled to a downstream turbine, and a combustion chamber in-between.

Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section. There, the high velocity and volume of the gas flow is directed through a nozzle over the turbine's blades, spinning the turbine which powers the compressor and, for some turbines, drives their mechanical output. The energy given up to the turbine comes from the reduction in the temperature and pressure of the exhaust gas.

Energy can be extracted in the form of shaft power, compressed air or thrust or any combination of these and used to power aircraft, trains, ships, generators, or even tanks.

PRINCIPLE OF OPERATION OF A TURBINE

Gasses passing through an ideal a gas turbine undergo three thermodynamic processes. These are isentropic compression, isobaric (constant pressure) combustion and isentropic expansion. Together these make up the Brayton cycle.

In a practical gas turbine, gasses are first accelerated in either a centrifugal or radial compressor. These gasses are then slowed using a diverging nozzle known as a diffuser, these process increase the pressure and temperature of the flow. In an ideal system this is isentropic. However, in practice energy is lost to heat, due to friction and turbulence. Gasses then pass from the diffuser to a combustion chamber, or similar device, where heat is added. In an ideal

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system this occurs at constant pressure (isobaric heat addition). As there is no change in pressure the specific volume of the gasses increases. In practical situations this process is usually accompanied by a slight loss in pressure, due to friction. Finally, this larger volume of gasses is expanded and accelerated by nozzle guide vanes before energy is extracted by a turbine. In an ideal system these are gasses expanded isentropicly and leave the turbine at their original pressure. In practice this process is not isentropic as energy is once again lost to friction and turbulence.

Fig1 A typical power Generation Turbine

If the device has been designed to power to a shaft as with an industrial generator or a turboprop, the exit pressure will be as close to the entry pressure as possible. In practice it is necessary that some pressure remains at the outlet in order to fully expel the exhaust gasses. In the case of a jet engine only enough pressure and energy is extracted from the flow to drive the compressor and other components. The remaining high pressure gasses are accelerated to provide a jet that can, for example, be used to propel an aircraft.

Fig2 Brayton cycle

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As with all cyclic heat engines, higher combustion temperatures can allow for greater efficiencies. However, temperatures are limited by ability of the steel, nickel, ceramic, or other materials that make up the engine to withstand high temperatures and stresses. To combat this many turbines feature complex blade cooling systems.

As a general rule, the smaller the engine the higher the rotation rate of the shaft(s) needs to be to maintain tip speed. Blade tip speed determines the maximum pressure ratios that can be obtained by the turbine and the compressor. This in turn limits the maximum power and efficiency that can be obtained by the engine. In order for tip speed to remain constant, if the diameter of a rotor is reduced by half, the rotational speed must double. For example large Jet engines operate around 10,000 rpm, while micro turbines spin as fast as 500,000 rpm.

Mechanically, gas turbines can be considerably less complex than internal combustion piston engines. Simple turbines might have one moving part: the shaft/compressor/turbine/alternative-rotor assembly (see image above), not counting the fuel system. However, the required precision manufacturing for components and temperature resistant alloys necessary for high efficiency often make the construction of a simple turbine more complicated than piston engines.

More sophisticated turbines (such as those found in modern jet engines) may have multiple shafts (spools), hundreds of turbine blades, movable stator blades, and a vast system of complex piping, combustors and heat exchangers.

Thrust bearings and journal bearings are a critical part of design. Traditionally, they have been hydrodynamic oil bearings, or oil-cooled ball bearings. These bearings are being surpassed by foil bearings, which have been successfully used in micro turbines and auxiliary power units.

Advantages of gas turbine engines

Very high power-to-weight ratio, compared to reciprocating engines; Smaller than most reciprocating engines of the same power rating. Moves in one direction only, with far less vibration than a reciprocating

engine. Fewer moving parts than reciprocating engines. Low operating pressures. High operation speeds.

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Low lubricating oil cost and consumption. Can run on a wide variety of fuels.

Disadvantages of gas turbine engines

Cost Less efficient than reciprocating engines at idle Longer startup than reciprocating engines Less responsive to changes in power demand compared to reciprocating

engines

The Gas Turbine driven Generator set is designed to accept a wide range of generator for maximum flexibility. It is a fully operational package equipped with all accessories necessary for normal operation when connected to a customer’s facility

The MARS100 turbine generator set has an ISO duty output of 10695KWe, heat rate of 11090kJ/KWe and an exhaust flow of 149930kg/hr and exhaust temperature of 485C

The GT is prime mover and a package power plant. It is an engine that operates under a series of thermodynamic process to produce an output power that can be used to drive an alternator to generate electricity.

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CHAPTER THREE

HOW DOES A GAS TURBINE WORK

The turbine is divided into seven auxillary systems, which are:

1. Start system.2. Lube oil system.3. Electrical control system.4. Gear system.5. Fuel system.6. Turbine system.7. Generator system.

THE START SYSTEM

The turbine uses a pneumatic start system that provide torque to initiate rotation and assist engine to a self-sustaining speed. A pneumaticactuator or compressed air engine is a type of motor which does mechanical work by expanding compressed air. Pneumatic motors generally convert the compressed air to mechanical work through either linear or rotary motion. Linear motion can come from either a diaphragm or piston actuator, while rotary motion is supplied by either a vane type air motor or piston air motor.

Pneumatic motors have existed in many forms over the past two centuries, ranging in size from hand held turbines to engines of up to several hundred horsepower. Some types rely on pistons and cylinders, others use turbines. Many compressed air engines improve their performance by heating the incoming air, or the engine itself. Pneumatic motors have found widespread success in the hand-held tool industry[1] and continual attempts are being made to expand their use to the transportation industry. However, pneumatic motors must overcome inefficiencies before being seen as a viable option in the transportation industry.

The reason for using pneumatics, or any other type of energy transmission on a machine, is to perform work. The accomplishment of work requires the application of kinetic energy to a resisting object resulting in the object moving through a distance. In a pneumatic system, energy is stored in a potential state

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under the form of compressed air. Working energy (kinetic energy and pressure) results in a pneumatic system when the compressed air is allowed to expand. For example, a tank is charged to 100 PSIA with compressed air. When the valve at the tank outlet is opened, the air inside the tank expands until the pressure inside the tank equals the atmospheric pressure. Air expansion takes the form of airflow.To perform any applicable amount of work then, a device is needed which can supply an air tank with a sufficient amount of air at a desired pressure. This device is positive displacement compressor.

At this time the start system uses twin turbine rotors to generate the necessary starying torque to transmit it to the engine through a common overrunning clutch in the accessary gear train. The starter helps the engine to gain speed of 900rpm(60% of the needed speed. When the engine speed is above theis speed (say 66%), air or gas is shutoff to the starter motor and they cease to rotate. The overrrunig clutch then disengages and allows engine to accelerate on its own.

THE EBS852, EBS862 PNUEMATIC ACTUATOR (Contrac)

Fig 3 the EBS852 ACTUATOR (Contrac)

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FUNCTIONALITYThe electronic units for the Contrac RHDE... and RSDE... series actuators are available in two sizes for rack mounting. Special parameters can be used to adapt the electronic units to the type of actuator concerned. The electronic units EBS852 (Contrac) are the interface between actuator / valves and fittings and process control system. The actuators / valves and fittings are positioned continuously, whatever the type of input signal (analog or digital). During continuous positioning the motor torque is varied steplessly until the actuator force and the restoring process forces are balanced. High positioning accuracy combined with excellent control quality and a long actuator life can even be achieved under varying load conditions and with short stroke times.

POWER CIRCUIT AND DESIGN OF EBS852 MODULE

In addition to the internal fuses, the EBS862 power electronic unit needs two other external fuses, which are delivered separately with the module.They ensure the safe operation of the EBS862 power electronic under the special starting conditions.The cable cross-section between the fuse and the electronic unit must be a minimum of 2.5 mm².

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Fig 4 electrical connection of the Actuator

CONNECTION ELEMENTS

Fig 5 electrical connection

1 Commissioning and service field (ISF)2 Signal3 Motor4 Mains5 Terminal6 Plug

CONTROL CIRCUIT AND DESIGN

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To prevent interference from electromagnetic fields, the signal and power cables in the connector housing must be routed and connected separately. A metal divider separates the two cable areas inside the connector. Attach the shielding as shown.The basic settings "Define end positions" and "Initial diagnosis" can be configured via the commissioning and service field (ISF). It can be used to adjust the actuator to the working area and set the direction without using a PC. The actuator can be further parametrized using agraphic user interface.The actuator or electronic unit is in a critical state (e.g., high temperature), which currently does not affect the actuator, electronic unit, process or persons. The actuator functions are available.Previous alarms are stored in the "Saved Alarms" area in the electronic unit. The graphic user interface use to output the stored alarms.The actuator or electronic unit is in a critical state, e.g., positioning time-out, which currently is impairing the actuator, electronic unit, process or persons. The actuator is switched off and the actuator functions are no longer available. Previous error messages are stored in the "Saved Errors" area in the electronic unit. Use the graphic user interface to output the stored errors. Error messages cannot be reset until the cause of the error has been eliminated.

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Fig5 Power Electronic Unit connection of EBS852 (Contrac)

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APPLICATIONS

The pneumatic actuator is used in the starting of a turbine. Its function Is very essential since the turbine cannot start without it. The actuator kinetic energy is converted into pressure energy, then into combustion chamber where fuel is injected into the pressurized air.

During the starting cycle, a torch protruding into the combustion chamber and fed by a separate fuel line, is ignited by spark plug. The torch in turn ignites the fuel air mixture entering the combustion chamber; continuous burning is maintained as long as there is an adequate flow of pressurized air fuel, the torch is later extinguished.

A fertilizer –lump forming machine is capable of heating and forming parts of various thicknesses. The parts must be held in their molded positions while the plastic is curing in its final form. The length of time needed to cure the plastic will vary depending on the thickness. This in turn will require a forming operation that has a variable time delay before the part is automatically released.The actuator can also be used in the industry’s Firewater Pump System

PROBLEMS FOR LOCAL MANUFACTURERS

The Module is not manufactured in Nigeria, therefore it has to be shipped. This fact pose a big challenge to the indigenous engineers as the maintenance cost is high. The parts are not readily available in Nigeria and the raw materials to build the parts are not gotten in the locally

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RECOMMENDATION

Good Knowledge of actuator will enhance the proper operation and maintenance of turbine

The materials for power electronic equipment can be explored in Nigeria, but the government has not yet looked into that. The Nation’s Power and Steel industry should be revived and funded by the government. This will enable indigenous engineers build and manufacture power electronics equipment locally and to Nigerian specification.

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REFERENCES

ABB Manual, “EBS852, EBS862 – Power Electronic Units for Cabinet installation of Control actuator – Operation Instruction

Notore Chemical Handbook

FireWater Pump Guide, Instrumentation Department, Notore Chemical Industry

Fluid Power Distributors Association - http://www.fpda.org/

Appendix

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