GAS TURBINE COGENERATION ACTIVITIES NEW POWER PLANTS FOR URALKALI S FACILITIES

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1 GAS TURBINE COGENERATION ACTIVITIES NEW POWER PLANTS FOR URALKALI S FACILITIES Abstract Alexander Gushchin, Siemens Russia Ian Amos, Product Strategy Manager, SGT-400, Siemens Industrial Turbomachinery Ltd, UK Guy Osborne, Sales Manager, Siemens Industrial Turbomachinery Ltd, UK Siemens Industrial Turbomachinery Ltd. is supplying four SGT-400 Gas Turbine generating packages rated at 12.9MWe each, to Uralkali JSC of Russia for installation at two potassium mines in Berezniki City. The SGT-400 engines are the key components for two cogeneration plants which are located in one of the main industrial centers of the Ural region. Each cogeneration plant will comprise two generating sets in order to provide efficient and reliable production of power and steam for use in the mines and for the manufacturing process. Cogeneration, the combined production of electrical power and heat, has been a well established technology for many decades. There are a number of factors which make the installation of a cogeneration facility attractive. These include significant cost savings relative to the separate supply of electricity and heat, and improved security of power supply. The evaluation carried out by Uralkali JSC looked at a number of alternative options for the prime mover, including reciprocating gas engines, and took into consideration life cycle costs, flexibility of operation, maintenance philosophies and regulatory requirements for the control of emissions. Gas turbines have the ability to burn a variety of fuels and the technology in the Siemens product range includes options for dual fuel operation, with automatic uninterrupted changeover from gas to liquid fuel and back again, whilst under load. Control of emissions resulting from the burning of fossil fuels is becoming increasingly important to comply with legislation and for protection of the environment. Low Emissions combustor technology minimises the generation of NOx and CO, whilst reduction of CO 2 is inherent in cogeneration schemes, with typical overall thermal energy efficiencies in excess of 80%. Gas turbine cogeneration solutions are suited for a wide range of industry segments requiring heat and power. Typical applications would be for the pulp and paper industries, and also the ceramics, food and beverage, chemical and pharmaceuticals industries. Cogeneration plants can also be used as an efficient means of supplying power and heat for local district heating schemes. The first two SGT-400 units were delivered to Uralkali JSC in January 2006 and the remaining two are scheduled for March These are the first SGT-400 gas turbines to be

2 supplied to the Russian Federation, although to date Siemens have supplied over 100 industrial gas turbines to existing customers in the Russian market, including Gazprom, Surgutneftegas, Rosneft, Lukoil, Sakhalin Energy and the Caspian Pipeline Consortium. New Power Plants for Uralkali JSC Uralkali JSC, a leading global supplier of potassium fertilizer, is proceeding with the construction of its power station installations at two potassium mines in Berezniki City, located in the Ural region of the Russian Federation. The power stations, rated at 25MW, will be constructed at Uralkali's Mining Divisions 1 and 4 and will each be equipped with two SGT-400 gas turbines. The gas turbines are fired on natural gas and are coupled to waste heat recovery units in the turbine exhaust to raise process steam. The power stations expand the capacity of the existing power grid and engineering infrastructure at the Uralkali sites. At a rating of 12.9MWe each, the Siemens' SGT-400 gas turbine closely meets Uralkali's requirements. The steam generated in the waste heat recovery units will be used in the production of potassium chloride. Construction at the sites started in 2005, managed by the general contractors UralVNIIPIEnergoprom, based in the city of Yekaterinburg. The power stations will start producing electricity in the summer of 2006, with an estimated project pay-back time of 6 or 7 years. In the second stage of the electro-generation development, it is planned to construct additional power stations to supply electricity to Uralkali's Mining Divisions 2 and 3. Energy costs represent 12 percent of Uralkali s total cost of production. The new power stations will enable Uralkali to supply 85 percent of its required electrical power and 100 percent of its thermal requirement. The savings made by generating their own electricity and using the waste heat for the production of steam will be very significant. The innovation will result in a major reduction in production costs and help Uralkali maintain their competitive edge in the potassium fertilizer market. The case for cogeneration. Industrial power users often have a requirement for energy in the form of both electricity and heat and have been able to choose between different technical solutions to satisfy this need. The emergence of large central electrical generation capacity in the developed countries, in the middle of the last century, with a good transmission infrastructure, led to a common practice of buying electricity from the generating companies. The heat demand is then met by burning fossil fuel locally. An alternative and well established technology has been to satisfy the energy requirements using cogeneration at the location of the demand. Cogeneration is the combined production of electrical power and heat from a single fuel source and has been used over many decades. The choice of energy supply is dependant on a large number of variables but will essentially be based on a consideration of the costs of energy and the security of supply.

3 In simple cycle operation, the heat contained in the exhaust gases of the gas turbine is lost to atmosphere, and with typical industrial turbine exhaust temperatures of about 500ºC, this limits the efficiency of the plant to about 35%. This would usually make the generation of electrical power on its own uneconomic, assuming there was an available grid connection. Factory Fuel Cool Exhaust Gas Water Returned to CHP Plant Steam Supply to factory process In the case of a gas turbine cogeneration system, the exhaust heat is recovered in a heat recovery system (or it can be used for direct drying in some applications). In the majority of installations, the heat recovery system will be a steam generator, raising either saturated or superheated steam for factory process or heating. The exhaust gases from the stack are now much lower than for the simple cycle case (140ºC) and overall thermal efficiencies are increased to more than 80%, making the economics of operation much more attractive. ~ Gas Turbine Generating Set The ratio of heat to power will vary considerably from industry to industry and even within the same industry segment. In many cases the required heat will exceed the amount that can be recovered in the exhaust waste heat recovery unit. Additional steam can be raised by adding supplementary firing to the system, burning more fuel in the turbine exhaust before the gas enters the boiler. Typical values for unfired and fired steam raising capabilities of industrial gas turbines are shown below, along with further detail for SGT-400. Steam Raising Capabilities for Gas Turbine Cogeneration Plant Steam (tonnes/hr) [12 bar, saturated] Steam (12 bar, 200) SGT-100 unfired fired SGT-300 SGT-400 SGT-500 SGT SGT-700 Power (MWe) Fired steam raising Unfired steam raising SGT-800 Steam values are indicative only. Actual values depend on site configuration.

4 Energy Cost Savings The main motivation for end users of this technology is to secure savings in energy costs. If the energy costs and operating profile of the factory or utility are identified, the potential savings can be calculated. Savings of more than 30% have been demonstrated, but local electricity tariffs and fossil fuel prices can vary significantly, as well as any grid connection charges. The example below shows how an estimate of the annual fuel savings can be calculated easily. The numbers are based on a real case. Site Requirements : 15,000 kwe electrical 32,041 KW thermal External supply Power (kw) Hours run 15,000 electric import 8,760 35,601 boiler gas fuel 8,760 (32,041/0.9) Assumptions Gas Turbine Power 12,861 kwe Gas Turbine Heat Rate 36,991 kw Gas Turbine Exhaust Heat 18,401 kw Gas price /kwh Electricity price /kwh GT running hrs 8,400 hrs/yr Boiler efficiency 90% Gas Turbine Cogeneration Solution Cost ( ) Power (kw) Hours Cost ( ) run 6,044,400 4,375,476 GT not running 15,000 electric import 32,041 thermal GT running 2,140 electric import (15,000-12,861) 36,991 gas turbine fuel 15,155 boiler fuel (32,041-18,401)/ ,400 8,400 8, , , ,896 4,359,463 1,786,112 10,419,876 7,400,685 Annual Savings 3,019,191

5 Security of Supply Many industrial processes operate continuously, and unscheduled interruptions to either electrical supply or steam can cause a complete shutdown of the plant and an expensive loss of production. An unreliable grid connection can be an important factor in deciding to install a cogeneration system. Normal philosophy would be to operate the gas turbine cogeneration plant in parallel with the grid, if available, with the turbine capable of operating in island mode without interruption to site power in the event of a grid failure. Cogeneration cycle variations There are a number of variations to the standard gas turbine cogeneration cycle. These include; Auxiliary Firing. When steam is required continuously for a process, auxiliary firing of the boiler will enable steam to be produced independently of the gas turbine by having an additional air intake at the entry to the boiler. When the gas turbine is shut down, the auxiliary burners continue to operate in order to maintain the steam supply. Trigeneration Trigeneration is the simultaneous production of Power, Heat and Cooling from a single fuel source. The steam from the waste heat recovery boiler is used for process (or heating) and a proportion is passed through an absorption chiller. This chiller cools a circulating chilling circuit which is used for air conditioning in the facility. The amount of heat and cooling generated can be varied according to facility needs. Combined Cycle with extraction for CHP The Combined Cycle is used for Power and Heat generation. It incorporates a gas turbine and steam turbine generating set. Process steam is extracted from the steam turbine casing and diverted to process via a control valve. Steam flow is varied according to the process needs. As more steam is diverted to the process, the output of the steam turbine power generator is reduced. Gas Turbine Direct Drying The exhaust gases from a gas turbine are directed into a drying cell or kiln. The purity of the hot exhaust gas is such that contamination of product is not a concern. This method eliminates the need for gas-fired or electrically heated kilns and is a very efficient method of generating power and simultaneously drying. Alternative schemes using auxiliary firing and air-to-air heat exchangers for indirect drying are also used. More detailed description of these can be found in A Guide to Cogeneration, (see references). Gas turbine cogeneration is also used in district heating applications, with additional efficiency gains made by using low grade waste heat for the production of hot water. An SGT-400 installed in Germany during 2005 has demonstrated an overall thermal efficiency in excess of 87%.

6 Cogeneration Evaluation Early in 2004 Uralkali commenced their evaluation of the various different technical schemes available that would enable them to eventually make theirthe equipment selection. Initially all options were considered, including conventional power plant using steam-raising boilers and steam turbine driven generators, and cogeneration plants driven by both reciprocating gas engines and gas turbines. The steam turbine design was discounted at an early stage as not meeting the project s full requirements due to lower overall efficiency and need for high pressure, high quality steam. Whilst the latest gas engines are very efficient at generating electricity, they have several drawbacks. These include only being able to produce small amounts of steam without additional firing,using the low temperature exhaust gases through a waste heat boiler; They are generally unable to operate using more than one type of fuel, the unit is very heavy and is therefore more difficult to transport, and it requires a large foundation due to the reciprocating design using a large crankshaft and pistons. It also requires frequent changes of lubricating oil. Gas engines also have a more intensive maintenance regime when compared to gas turbines, again due to the number of moving parts and the wear between components within the engine. Once the selection of the prime mover had been narrowed down to gas turbines, Uralkali investigated several options including both domestic and Western manufacturers. Within the size range considered there are two basic designs of gas turbine, aeroderivative and industrial. The aeroderivative gas turbine is very closely based on units originally designed for use on aircraft but additionally has a separate power turbine to drive the generator. The aeroderivative unit is manufactured from materials designed to save weight and is usually more expensive. Aeroderivatives can be more efficient than the industrial design in simple cycle but the low exhaust temperature gives lower steam raising capability and lower overall thermal efficiency. Its biggest downfall when compared against the industrial design is the more rigorous maintenance schedule resulting in reduced availability. The industrial design of gas turbine has a life expectancy of at least two hundred thousand operating hours that equates to twenty-five years, provided that the OEM maintenance recommendations are followed. This is possible due to the more heavy duty design of the main casings, blades and combustion systems and the lower stresses and temperatures within the engine core. However, the latest generation of industrial gas turbines now have impressive efficiency figures coupled with very low exhaust emissions when using low emissions combustions technology. The Siemens SGT-400 offers high electrical efficiency along with good steam-raising capability due to the high temperatures and low mass flow of the exhaust gases. The generator package is supplied in two parts, one containing the engine core along with all its auxiliary systems and the other comprising the AC generator and reduction gearbox. This allows transportation by road or rail in a fully assembled and tested state. Note: the SGT-400 meets the Russian rail authorities requirements for rail bridge and tunnel access. Industrial gas turbines generally require one scheduled inspection each year that equates to approximately eight thousand five hundred operating hours. This inspection varies annually, depending on the total number of hours operated by the engine core, the operating environment and the number of start cycles. In the case of the SGT-400, the core engine requires a major overhaul after six years or forty-eight thousand operating hours. One of the advantages over other gas turbine manufacturers is the ability, if necessary, to carry out most maintenance work at site with the engine still installed on the package. Due to the casing

7 design with horizontally split joints, even turbine blading and combustion system components can be changed at site. Uralkali also looked at the local service support capabilities of the various suppliers, as they appreciated the difficulties of exporting equipment to allow maintenance procedures. Even temporarily exporting components requires export licenses and often results in delays, especially when trying to re-import the item that may have been overhauled or modified and appears different to the item originally exported. Siemens now has a dedicated service office in Moscow that employs local Customer Support Managers to answer technical queries, arrange the supply of specialist engineers and spare parts and liaise between the end user and the main manufacturing centres in Europe. Siemens employ Russian nationals who have been factory trained to service our range of over one hundred units already operating locally and are now opening a new service centre in Krasnodar that will be used to store spare parts and specialist tooling plus be equipped to overhaul engine cores without the need to transport them outside of Russia. All of the above service-related issues were taken into account by Uralkali during the feasibility study. Fuel capabilities The Uralkali installation, like the vast majority of cogeneration applications, will use natural gas as fuel, although industrial gas turbines have a high degree of flexibility in respect of fuel type, and operation is possible on a range of gaseous and liquid fuels. The list of fuels which can be used is continuing to expand due to ongoing combustor development programmes. Increasingly, there is a wish to exploit opportunity fuels which are generally those fuels considered to be waste products. Gaseous Fuels Natural Gas Wellhead Gas Refinery Waste Gas Sewage Gas Landfill Gas Coke Oven Gas Coal Bed Methane Bio Gas Liquid Fuels Diesel Kerosene Ethanol Naphtha LPG However many of these alternative fuels may require additional treatment to remove constituents which could cause damage to the turbine. For example; Metals and acids cause corrosion in the gas turbine and should be removed to within acceptable limits. Tars and liquid slugs should be removed from gas fuels to within acceptable limits. Particulates can cause erosion of gas turbine components and should be removed to within acceptable limits. Dual fuel capability, which allows automatic uninterrupted changeover from gas to liquid fuel whilst under load and back again, is another feature providing additional security of supply. Environmental Considerations The trend of increasing legislation on the control of emissions from fossil fuel power plants is forecast to continue. This will put more emphasis on thermal efficiencies and also low

8 emissions combustor technologies. Gas turbine cogeneration schemes compare favourably with other technologies; Pollutant Effect Method of Control Carbon Dioxide Greenhouse gas Cycle Efficiency Carbon Poisonous DLE System Monoxide Sulphur Oxides Acid Rain Fuel Treatment Nitrogen Oxides Ozone Depletion DLE System Smog Hydrocarbons Poisonous Greenhouse gas DLE System Smoke Visible pollution DLE System CO2 emissions are minimised by using inherently efficient power and heat generation schemes such as Cogeneration, with over 80% thermal efficiency typically achieved. Industrial gas turbines have well proven low emissions combustion systems to limit the production of Nitrogen Oxides and Carbon Monoxide at levels well below that achieved for reciprocating units. Siemens Industrial Gas Turbine Experience in the Russian Federation The first two Siemens SGT-400 gas turbine generator packages for delivery to Uralkali were despatched from the factory in England in January 2006, with the remaining two being despatched in March These are the first SGT-400 gas turbine packages to be supplied into the Russian Federation although to date Siemens have supplied over one hundred industrial gas turbines to customers in the Russian market and Siemens are currently the leading Western supplier of gas turbines in the 4MW to 15MW range into the Russian Federation. Existing operators include the Caspian Pipeline Consortium, Gazprom, Krasnodar Heat and Power, Lukoil, Moscow City, Rosneft, Sakhalin Energy, Surgutneftegas, Togliatti Azot and Total. Whilst the majority of these units operate on either pipeline natural gas or diesel fuels, several use wellhead gas taken from the oil fields of Siberia. This wellhead gas would normally be flared to atmosphere and can contain contaminants including hydrogen sulphide (H 2 S), but by burning it in a gas turbine the power is effectively produced for free, at the same time as reducing emissions. It is important that all chosen suppliers can work comfortably with the local design institutes and EPC contractors as well as working to the latest GOST-R and ROSTECHNADZOR Certification standards to allow importation and also installation, commissioning and operation of equipment. Experience of supplying and installing equipment for operation in the harsh environments in Russia is also critical and Siemens have units operating at winter temperatures to below -57 O C using a variety of different heating designs to ensure the combustion and ventilation heating systems operate successfully. In the Uralkali project the excess energy produced by the lubricating oil coolers is used to provide heat for buildings, again increasing total the efficiency of the plant. Siemens have identified the Russian Federation as one of the key world markets for both power generation equipment and plants and will continue to invest heavily in the local infrastructure and support networks to allow our customers to operate their gas turbine based cogeneration systems to the highest levels of availability and reliability. There are enormous opportunities for cogeneration plants in Russia, both at new industrial sites and also at existing facilities due to expansion or replacement of old inefficient equipment.

9 REFERENCES A Guide to Cogeneration : The European Association for the Promotion of Cogeneration