7th INTERNATIONAL COLLOQUIUM ON EUCALYPTUS PULP Vitória, Espírito Santo, Brazil COMBINED HEAT & POWER A SOLUTION TO THE ENERGY CRISIS IN BRAZIL
BRAZIL’S ELECTRICITY GENERATION ACTUAL SCENARIO I Brazil has the third largest electricity sector in the Americas, behind the United States and Canada. The electricity generation capability of the country by 14/05/2015 distributes as follows (source ANEEL): INSTALLED TYPE QUANTITY % POWER (KW) Hydropower Plants (>30MW) - UHE 201 84.778.838 62,22% Thermoelectric Plants - UTE 2.408 38.482.762 28,24% Wind Power Plants - EOL 266 5.862.249 4,30% Hydropower Plants (1-30MW) - PCH 477 4.797.722 3,52% Hydropower Plants (<3 MW) - CGH 496 326.443 0,24% Nuclear Power Plants - UTN 2 1.990.000 1,46% PV Plants - UFV 317 15.179 0,01% TOTAL 4.167 136.253.193
BRAZIL’S ELECTRICITY GENERATION ACTUAL SCENARIO II Currently Brazil faces a crisis of power generation capacity mainly caused for two reasons: The investment in electricity infrastructure in Brazil in recent years has not been aligned with the growth of the electricity demand in the country. Brazil’s electricity generation is primarily based on large hydropower plants. After some of the drier rain sessions in years the level of reservoirs is alarmingly low. This crisis is producing strong increases in electricity prices during 2015 as well as problems of electricity supply for both the industry and the services sector. Because of this Brazil has an urgent need to increase the electricity generation capacity in the system. Also the industries need to find a way to reduce the costs of their electricity consumption and guarantee their power supply
SUSTAINABLE ELECTRICITY GENERATION DEVELOPMENT A sustainable development the electric generation sector, that is to say, the expansion of electricity generation capability in the more efficient and environmental friendly way, is a key component of energy policy in Brazil. A sustainable development may be achieve by promoting technologies, which enhances some of the following features: RENEWABLE RESOURCES HIGH EFFICIENCY ENERGY CONVERSION DISTRIBUTED GENERATION LOW ENVIRONMENTAL IMPACT
ALTERNATIVES FOR SUSTAINABLE ELECTRICITY GENERATION DEVELOPMENT We will introduce two alternatives for the sustainable development of electricity generation that have great potential of growth in Brazil that may be of interest to the Wood and Pulp and paper industry. BIOMASS FUELED POWER PLANTS. BIOMASS AND GAS FUELED COMBINED HEAT AND POWER (CHP) PLANTS.
CHP DEFINITION COGENERATION or COMBINED HEAT AND POWER (CHP): Is the simultaneous generation of electric power and useful heat (steam, hot/cold water … ) from the same fuel source. The process of transforming the energy from any source into electricity is never loss-free. In thermo electrical generation, 50% or more of primary energy is lost, most of it transformed to heat that is usually wasted. Combined Heat & Power (CHP) is a technique used to obtain both electricity and useful heat from a single energy source. This is accomplished by using the heat generated inevitably in the electrical generation process to satisfy a local demand of thermal energy (hot/cold water, steam, hot air … ) instead of wasting it. With CHP Wasted Heat is turned into Useful Heat.
CHP BENEFITS INCREASE THE ENERGY EFFICIENCY and therefore produces significant savings in primary energy. The fuel consumption is lower when used to produce both electricity and heat simultaneously (CHP) than when is used to produce them separately (Conventional Generation) REDUCTION OF EMISSIONS of greenhouse gases, particularly CO2, Kyoto Protocol friendly Technology. Due to the fact that CHP is DISTRIBUTED GENERATION, it leads to lower transport and transformation losses in the network, and less electrical infrastructure requirements
CHP VS CONVENTIONAL GENERATION I Conventional Thermal Hot water/steam Boiler Power Plant with gas burner WASTE HEAT 10 – 15 % WASTE HEAT 50 – 65 % ELECTRICITY USEFUL HEAT FUEL 100% FUEL 100% 35- 50% 85 - 90%
CHP VS CONVENTIONAL GENERATION Ii GAS ENGINE CHP PLANT WASTE HEAT 10 – 20 % ELECTRICITY 40- 45 % FUEL 100% USEFUL HEAT 40- 45% OVERALL EFFICENCY (ELECTRIC AND THERMAL) 80 – 90 %
CHP BASIC PROCESS DIAGRAM GAS USEFUL HEAT Exhaus t High Temperature 400º ENGINE WASTE HEAT Refrigeration Circuit 90º 45º 40º 80º Low Temperature Refrigeration Circuit ELECTRICITY
BIOMAS FUELED POWER PLANTS The term BIOMASS refers to any biological material derived from living or recently living organisms. It most often refers to plants or plant- derived materials which are specifically called lignocellulosic biomass. As an energy source the biomass is a very interesting alternative to fossil fuels (natural gas, fuel, oil ...) since it is a RENEWABLE FUEL MANAGEABLE CHEAP AUTOCHTHONOUS ENVIRONMENTAL FRIENDLY IT IS ALSO POSSIBLE TO USE BIOMASS AS FUEL OF A CHP PLANT.
LIGNOCELLULOSIC BIOMASS TO ELECTRICITY HEAT Rankine Cycle: Water Steam Cycle ORC Thermal process: Combustion ELECTRICITY Chemical process: Gasification LIGNOCELLULOSIC Otto Cycle: Engines Bryton Cycle: Turbine BIOMASS SYNGAS
ELECTRICITY GENERATION BASED ON BIOMASS GASIFICATION GASIFICATION is a complex thermochemical process that occurs in a low oxygen atmosphere in which a carbonaceous substrate, through a series of reactions that occur at a certain temperature in the presence of a “gasification agent” (air, oxygen … ) is transformed into a combustible gas of low calorific value. The resulting gas mixture is called syngas (from synthesis gas or synthetic gas) or producer gas and is itself a fuel. The advantage of gasification is that using the syngas is potentially more efficient than direct combustion of the original fuel because it can be combusted at higher temperatures. If the syngas is passed through a process of cleaning and filtering (removing tar and other condensates) it can even be used in gas engines to produce electricity with high efficiency.
BIOMASS GASIFICATION BASIC PROCESS DIAGRAM BAG FILTER BIOMASS Raw gas filtered HEAT ECHANGER / BIOMASS CHILLER GASIFIER Solid particles, ahses … Tars, oil … SYNGAS Raw gas AIR
BIOMASS GASIFICATION STAGES During the gasification process, hundreds of chemical reactions take place but the overall process can described in four stages: The biomass dehydration or DRYING PROCESS. Typically, the resulting steam is mixed into the gas flow and may be involved with subsequent chemical reactions. In the PYROLYSIS volatiles are released and char is produced. The process is dependent on the properties of the biomass carbonaceous material. The COMBUSTION process occurs as the volatile products and some of the char reacts with oxygen to primarily form carbon dioxide and small amounts of carbon monoxide, providing the necessary heat for the subsequent gasification reactions. The GASIFICATION process occurs as the char reacts with steam to produce carbon monoxide and hydrogen. high efficiency.
BIOMASS GASIFIERS TYPES These are the most typical configurations for SMALL-MEDIUM SIZED PLANTS. Counter-current fixed bed or updraft gasifier. Co-current fixed bed or downdraft. Fluidized bed (at atmospheric pressure or pressurized): Gasification occurs on a fluidized bed of inert material, typically sand.
A CHP PLANT BASED ON BIOMAS GASIFICATION PROJECT - ST2 BARCELONA (SPAIN) As part of the Parc de l’Alba (Cerdanyola) DH&C network project based on CHP, following the construction of the 16 MW CHP plan based on gas engines (ST4), it is planned to construct a 2MW CHP Plant based on woodchips gasification (ST2).
A CHP PLANT BASED ON BIOMAS GASIFICATION PROJECT - ST2 BARCELONA (SPAIN)
ELECTRICITY GENERATION BASED ON BIOMASS COMBUSTION It is possible to produce electricity with biomass in more conventional way in a RANKINE CYCLE BASED POWER PLANT. The biomass can be burned in a watertube boiler to produce high pressure steam (>400º) to be expanded in a steam turbine that will produce electricity. The expanded steam need to be condensed and the cycle starts again. Of course, it is a very mature and well proven technology but has the inconvenient that in order to achieve good efficiency levels very large plant sizes are required. A very interesting alternative FOR SMALLER SIZES OF PLANT, which is more suitable for to the quantities of biomass typically managed industrially with a more moderate logistics, is the ORGANIC RANKINE CYCLE (ORC). ORC is just the Rankine cycle applied to a silicon oil fluid instead of water; this fluid has the appropriate thermodynamic characteristics that allow high cycle efficiencies with lower temperature heat input.
ORC MODULE The complete Rankine cycle is carried away in the ORC Module. ORC MODULE EVAPORATOR HIGH TEMPERATURE ELECTRICITY OUT HEAT IN SILICON TURBINE OIL CYCL E PUMP CONDENSER ELECTRICITY IN LOW TEMPERATURE HEAT OUT
ORC BASED POWER PLANT BASIC PROCESS DIAGRAM WASTE HEAT WASTE HEAT 150º Flue gases Condenser ORC MODULE Refrigeration BIOMASS Circuit 50º BOILER Thermail Oil Circuit 40º 310º 250º ELECTRICITY BIOMASS
Recommend
More recommend
