Training programme on Energy Efficient technologies for climate change mitigation in Southeast Asia. Cogeneration

Transcription

1 Training programme on Energy Efficient technologies for climate change mitigation in Southeast Asia Cogeneration

2 Session Agenda: Cogeneration Introduction Types of steam turbine cogeneration system Types of gas turbine cogeneration system Cogeneration classification Performance evaluation Energy efficiency opportunities Case Studies

3 Introduction What s a Cogeneration/CHP System? The sequel generation of multiple forms of useful energy in one integrated system Defined by its prime movers that is the equipment driving the system Prime movers include reciprocating engines, combustion or gas turbines, steam turbines, microturbines, and fuel cells 3

4 Introduction Efficiency Advantage of CHP Conventional Generation (58% Overall Efficiency) 36 Units (Losses) 60 = 40% Uni ts Combined Heat & Power (85% Overall Efficiency) 40 = 85% 34 Uni ts 6 Units (Losses) 10 Units (Losses) 4

5 Introduction Benefits of Cogeneration (CHP): Increased efficiency of energy conversion and use Lower emissions, especially CO2 Some waste materials such as refinery gases, process or agricultural waste can be used Large cost savings Opportunity to decentralize the electricity generation, particularly for natural gas systems One of the most important vehicles for promoting liberalization in energy markets 5

6 Type of Cogeneration System Steam Turbine Cogeneration System Widely used in CHP applications This is the oldest prime mover technology with capacities from 50 kw to hundreds of MWs for large plants The thermodynamic cycle is the Rankin cycle that uses a boiler Most common are backpressure and extraction condensing types, choice depends on quantities of power and heat, quality of heat and economic factors 6

7 Type of Cogeneration System Back Pressure Steam Turbine Steam exits the turbine at a higher pressure that the atmospheric Boiler HP Steam Turbine Advantages: -Simple configuration -Low capital cost -Low need of cooling water -High total efficiency Fuel Condensate Process LP Steam Disadvantages: -Larger steam turbine -Electrical load and output can not be matched Figure: Back pressure steam turbine

8 Type of Cogeneration System Extraction Condensing Steam Turbine Steam obtained by extraction from a intermediate stage Remaining steam is exhausted Relatively high capital cost, lower total efficiency Control of electrical power independent of thermal load HP Steam Boiler Turbine Fuel LP Steam Condensate Process Condenser Figure: Extraction condensing steam turbine 8

9 Type of Cogeneration System Gas Turbine Cogeneration System Operates on the thermodynamic Brayton cycle by using the excess power produced that is not consumed by the compressor Natural gas is the most common fuel and the typical range varies from a fraction of 1MW to 100 MW Thanks to rapid developments it has gained technology progress, cost reductions and greater environmental performance 9

10 Gas Turbine Cogeneration Systems Open Cycle Gas Turbine Cogeneration Systems Open Brayton (Joule) cycle: compressor derives atmospheric air at increased pressure to the combustor Old/small units: 15:1 New/large units: 30:1 Fuel Combustor Exhaust Gases HRSG Condensate from Process Steam to Process Exhaust gas at C High pressure steam produced that can also drive a steam turbine G Generator Compressor Turbine Air Figure: Open cycle gas turbine cogeneration

11 Cogeneration Classification Topping Cycle The supplied fuel first produces power followed by thermal energy Thermal energy is a byproduct used for process heat or other This is the most popular method of cogeneration 11

12 Cogeneration Classification Bottoming Cycle Primary fuel produces high temperature thermal energy The rejected heat is used to generate power through a recovery boiler and turbine generator Suitable for manufacturing processes and used in cement, steel, ceramic, gas and petrochemical industries 12

13 Performance evaluation Performance Terms & Definitions Overall Plant Heat Rate (kcal/kwh): Ms x ( hs hw) Power Output ( kw) Ms = Mass Flow Rate of Steam (kg/hr) hs = Enthalpy of Steam (kcal/kg) hw = Enthalpy of Feed Water (kcal/kg) Overall Plant Fuel Rate (kg/kwh) Fuel Consumption * ( kg/ Power Output ( kw) hr) 13

14 Energy Efficiency Opportunities Steam Turbine Cogeneration System a) Condenser vacuum Most important factor as small deviations can result in significant efficiency changes Reasons for changes include differences in cooling water inlet temperature and flow, fouled condenser tubes or air leaks b) Steam temperature and pressure Variations can be due to errors in plant design c) Part load operation and starting & stopping Operations of certain loads for certain periods have major influences on thermal efficiency 14

15 Energy Efficiency Opportunities Gas Turbine Cogeneration System a) Gas temperature and pressure Gas temperature and conditions at the gas turbine inlet may inhibit efficiency b) Part load operation and starting & stopping Operations of certain loads for certain periods have major influences on thermal efficiency When the plant comes on and off line affect thermal efficiency due to energy losses c) Other Other factors include changes in temperatures, high mass flows and pressure changes 15

16 CASE STUDY 1

17 EXISTING CONDITION Steam Generation - 60 Tons/hr at 10kg/cm² Fuel Oil Fired Boilers Evaporation Ratio - 1:14 Fuel Oil Cost - US $ 500/Ton G. C. V. of Fuel Oil - 10,200 KCal/kg Enthalpy of Steam KCal/kg Electricity Consumption - 12,000 KWh/hr Electricity Cost - US $ 0.10/KWh Plant Operating hrs per year - 350x24 = 8400 hrs Work out cost economies of Co-generation scheme as per following details:- Installation of Fluidized bed Rice Husk Fired Boiler Steam Generation - 60 Tons/hr. at 40 Bar, 380 C, Super heat Enthalpy of steam kcal/kg G. C. V. of Rice Husk kcal/kg Cost of Rice Husk - US $ 30/Ton Evaporation Ratio

18 COST OF ENERGY CONSUMED Cost of Thermal Energy Fuel Oil Consumption = 60/14 = 4.28 Tons/hr Annual Fuel Oil Consumption = 4.28x8400 = Tons/hr Cost of Fuel Oil = 35952x500 = or 18 US Million $ Cost of Electrical Energy Electricity Consumption = 12,000 kwh/hr Annual Electricity consumption = 12,000 x 8400 = Million kwh Cost of Electricity = x 0.1 = Million US $ Total Cost of Energy = = Million US $

19 COST ECONOMICS OF CO-GENERATION SCHEME 60T/hr 40Bar, 380 C, H=755 kcal/kg 60T/hr 10Bar, H=660 kcal/kg Calculate Power Generation if turbine & alternator Losses are around 10% Heat Balance across extraction Turbine= 60,000( ) = 5,700 x 10³ kcal/hr Net Heat available for power Generation = 5,700 x 10³ x 0.9 kcal/hr = 5130 x 10³kCal/hr (We know 860kcal = 1kWh ) = 5130 x 10³/860 = 5965kWh/hr or = 5965 x 8400 = 50.1Million kwh/yr

20 COST ECONOMICS COST OF RICE HUSK USED IN FLUIDIZED BED BOILER Steam Generation - 60T/hr at ; 380 C at 40 Bar Evaporation Ratio Cost of Rice Husk - US $ 30/Ton Rice Husk Consumption - 60/3.65 = tons/hr Annual Rice Husk Consumption x 8,400 = 1,38,096Tons/yr Cost of Rice Husk x 30 = US $ Million COST OF ELECTRICITY PURCHASED FROM GRID Total Power Consumption Power Generated through Co-generation = = 50.7 Million kwh Cost of Electricity = 50.7 x 0.1 = 5.07 Million US $ Total Monetary Savings = ( ) = Million US $

21 CASE STUDY 2

22 Case Study : Utilization of Solar Energy (steam, heat) for HVAC requirements An auto ancillary company in north India has an abundance of sun-light throughout the year The total building air-conditioning load of 110 TR The roof top area available for the utilization of solar energy was 700 sq m. which could lead to cooling of about 30 TR Achieved through 20 solar concentrators with a 30 TR Vapor Absorption Machine, VAM with a COP of 1.1

23 Product specifications The main component of the system is the 16 m2 Scheffler solar parabolic concentrator. It concentrates the sun light in to approx. 30 cm. where the high optical temperature around 500 Deg C is generated. This temperature is carried in by a circular receiver by means of heat exchange in between the water, which is circulating inside the receiver and the optical temperature to generate hot water of 140 degree centigrade. The solar parabolic concentrators are tracked automatically, but the focus is fixed at the point of receiver. PRODUCT FEATURES Dish Area - 16 sq.m Dish Rating - 5 kw/h. Fixed Focus design with PLC based control system for daily tracking. Dual Axis tracking system.

24 Schematic Diagram

25 Technical details

26 Cost Economics Sr. No Description Cost in USD 1 Price for 20 Nos Solar Concentrators Central Tracking system Storage tank and heat exchanger with valves and instrumentation Structure and supports for Solar Frame Double Effect VAM of 30 TR with first charge of Lithium Bromide Balance of Plant hot water pumps and piping, cooling tower, cooling water pumps and piping Solar Dish Erection and Commissioning Erection and commissioning of VAM and Balance of Plant Total

27 For further inquiries Contact