You are looking for wood pellet burners boilers
.
Below you will find the wood pellet burners boilers information you need. I would like to share my experiences and findings with you.
 |
 16 24 30 kW Central Heating Wood Pellet Boiler AUTO  US $6,155.29
|
16 24 30 kW Central Heating Wood Pellet Boiler AUTO US $6,774.69
|
16 24 30 kW Central Heating Wood Pellet Boiler AUTO US $7,665.08
|
 6x 12 Length Simpson Duratech Galvanized Liner 9403GA US $47.99
|
 6x 6 Length Simpson Duratech Galvanized Liner 9402GA US $32.99
|
 6x 36 Length Simpson Duratech Stainless Liner 9406 US $115.99
|
| The Best Prices on the Internet |
Enhanced Power and Heat Generation From Biomass and Municipal Waste
Introduction Generally, the electricity production from a waste-burning plant is quite low, due to the fact that it is tricky to burn waste. Waste is a fuel with a “wide composition” that includes not only substances that require extensive exhaust gas cleanup but also corrosive elements that restrict the temperatures of the steam tubes in the boiler. Thus the steam cycle will be quite small from a thermodynamic point of view with low inlet conditions (typical temperature of 210°C) on the back pressure steam turbine. By adding a gas turbine to the system, using the gas turbine exhaust steam generator as a superheater for the low temperature steam from the waste boiler, an effective combined cycle power plant with a larger steam cycle is generated. With this solution, the overall transformation of the fuel energy to electricity and heat for district heating will be very good. The fuel for the gas turbine will, of course, be dependent on availability. Normally, natural gas is preferable from the point of view of both economic and environmental considerations. The fuels Municipal waste consists largely of recycled material, (gas, metals, newspapers, plastic bottles and cans etc) but there is a residue consisting of food leftovers, scrap paper, polyethylene etc. that has to be taken care of. Most of the waste is renewable biomass. Burning it in incineration plants, as an alternative to simple disposal, is becoming very common, especially for large and middle size towns, but even in smaller communities with district heating systems. The combustion technology and exhaust gas treatment have improved to make the rather difficult combustion of municipal waste environmentally possible even in small plants. The municipal energy system often includes the use of some biomass, in special boilers or added to the waste. Biomass in the form of wood chips or pellets has become a common fuel for municipal heating in a places, but so far not for electricity production. From the combustion point of view, biomass and municipal waste are fairly similar in heating value. Both fuels have corrosive elements of similar and different kinds, which prevent high surface temperatures in the boiler. The municipal waste contains some polyethylene, metals etc. that will produce chlorides, ammonia and metal vapors and salts. The wet compounds could prevent good combustion with dioxin as a result. The biomass in the form of wood chips also produces ammonia and alkali metal vapors and salts but has a more even composition and less moisture. The plants Waste incineration or biomass plants are normally just boilers for heat production. The use of the district heating system as a heat sink for electricity production will increase with increasing cost of electricity and with the expansion of CO2 trading. In the plants for electricity production, steam turbine systems have been included. However, due to the corrosiveness of the combustion gases, the steam temperature has to be low, in order to avoid excessively high surface temperatures on the boiler tubes. The plants are often built up in stages following the population development and the expansion of the district heating system. The stage to include electricity production is frequently late in the process, which means that the steam cycle will not always be optimal but adjusted to fit the existing plant as well as possible. The conclusion is that the electricity production with steam turbines has a rather low alpha ratio (= electricity/heat ratio) at around 0.2.The combined cycle a way to substantially boost the electric power and heat production from a waste incineration or biomass plant is to include a combined cycle. The low value steam from the incineration plant is then superheated in the waste heat recovery boiler of the gas turbine. The steam quality is then improved to suit a rather large back pressure steam turbine with heat condenser. With such a cycle the performance figures are very much improved with an alpha ratio of 0.52 and a total efficiency of around 90%. The gas turbine fuel The fuel for the gas turbine could be the conventional ones, natural gas or diesel oil. Preferably industrial waste gases (refinery gas, coke oven gas etc) or, in the future, biomass-based fuels could be used. In Sweden, one plant is fired with diesel oil and another with liquid propane, gasified on site. Plant description In a two incineration plants have been retrofitted with combined cycles as described above. In one of the plants the gas turbine has been closed down and sold off for two reasons: ? The municipality did not expand as expected ? The fuel cost went up more than expected. At the start of the project, propane was a surplus product from the Norwegian oil and gas fields, but has later become quite expensive. The combustion system and the fuels The gas turbine is equipped with a conventional combustor and 18 fuel injectors for dual fuel operation. The present fuel is good diesel oil with high ash melting point (>900°C) to minimize risk of corrosion of the gas turbine hot parts. The diesel oil is mixed with water in the fuel injectors at a w/f ratio of 0.8 to reduce NOx from around 210 ppmv to 40 ppmv. The addition of water with the fuel increases the turbine output by around 1 MWe, but also the stack losses by 3.7 MW. Natural gas will become available at the plant within a few years, which will not only reduce the cost for the gas turbine fuel, but also provide more operating hours and longer times between overhauls. The present conventional combustor and dual fuel injectors of the SGT-600 can be used with natural gas, but they can also be directly exchanged to a Dry Low Emissions (DLE) combustion system, suitable for natural gas and mixtures of natural gas and biogas. With the DLE burners, the water injection can be deleted and the stack losses reduced. The total efficiency will be increased to around 93%. The NOx level at the gas turbine exhaust will come down from 40 ppm to 25 ppm. At the site there is a biogas plant producing gas by fermentation of waste from farming. The gas is used mainly as fuel for busses, cars and trains. In the future, this type of gas could be mixed with the natural gas to fuel the gas turbine. The steam turbine The admission data of the low pressure steam turbine are 1.5 MPa/430°C. During operation, the turbine is coupled directly to the same generator as the gas turbine, that is, at 3000 rpm, Producing 25 MWe electric power. The steam turbine has a “district heating exhaust” which means that the steam flow is divided in two parts, condensing at somewhat different pressure levels in order to achieve the highest heat recovery. The Waste Heat Recovery Unit (WHRU) The gas turbine exhaust gases are ducted to an unfired boiler equipped with a superheater, boiler and economizer. Some steam is raised in the WHRU, but the main flow is the saturated steam from the incineration boiler. The economizer is used to preheat the condensate. The stack temperature for the oil-fired gas turbine is limited to 135°C to prevent SO3 condensation and corrosion. For a natural gas fired unit, the exhaust temperature could be lowered to 85°C, reducing the stack losses. The superheater is divided in two parts in order to position an ammonia-based Selective Catalytic Reactor (SCR) for NOx reduction at a suitable temperature level. The combination of this SCR and the water injection in the gas turbine combustor means that the NOx emission level is very low, around 5-7 ppmv at 15% O2 on diesel oil. For a gas-fired unit with DLE burners in combination with the SCR, NOx-levels as low as 3 ppmv at 15% O2 would be achieved. Heat production only The plant can be operated for heat production only. All the steam from the boiler is then directly condensed to produce district heating water with an incoming temperature of 50°C and an outgoing temperature of 90 to 115°C, depending on the time of the year. The total heat production from the direct condenser and the economizers in the incineration boiler is around 87MW, which translates into a fuel utilization of 93%. Operation with the combined cycle The steam from the incineration boiler is then going to the WHRU of the gas turbine for superheating before expansion in the steam turbine. There are two modes of gas turbine operation due to a difference in production tax on electricity produced in a “district heating” mode or in a “power generation” mode. The power generation mode ( = gas turbine at full load) is only profitable when electricity prices are high, so even in wintertime the plant has most often been operated in the district heating mode ( = 60-70% gas turbine power), producing as much district heating as at the “heat production only” mode. Conclusions ? Waste incineration and biomass-fired plants will be used in the future for electricity production. ? The retrofitting of steam turbines to the plants is not very effective due to the low steam data. The power to heat ratio will be low, around 0.2. ? A way to substantially improve the electricity production is to retrofit with a combined cycle fired with current conditions on diesel oil or natural gas but in the future on biogas. A power to heat ratio of >0.5 can be reached. An optimized plant could reach a power to heat ratio of =0.6 and a total efficiency of 93%. ? In the future the fuel to the gas turbine could be gasified biomass, which would make such a plant fit the strategy to operate mainly on renewable energy.
About the Author
Assistant professor in lord venkateswara engineering college.I am doing phd in sathyabama university, Tamil Nadu,India.
Posted in 
Tags: 
