CNIM entered the biomass market in 1989 with the acquisition of Babcock Entreprise, an internationally-recognized provider with hundreds of customer references. Since then, CNIM has built numerous power plants that use biomass, either to generate electricity, steam or both in co-generation. As a manufacturer of equipment and a contractor operating on an international scale, CNIM provides turnkey biomass power plants. In a fully-integrated approach, the Group designs the essential equipment for the plant using its own proprietary techniques, orders and monitors the work carried out by its industrial partners or sub-contractors, and commissions the plant when installation is complete. CNIM’s advanced expertise and production resources are there to supports its clients throughout the lifecycle of the plant. The Group has developed a range of its own technologies, which are constantly evolving and which comply with the strictest regulations in terms of performance and respect for the environment.
CNIM carries out the design and installation of the following aspects of a new plant:
- energy recovery
- flue gas treatment and treatment of residues (using LAB processes)
The most widely used system for the combustion of biomass is a rotating grate spreader-stoker. Ideal for all types of biomass, the rotograte process can also be used with other fuels, so that it can adapt to seasonal variations in biomass production. Sugar cane bagasse is one example of that seasonality, with the addition of other fuels enabling the plant to provide year-round electrical power.
The biomass is loaded into feeders in carefully calibrated quantities before being pneumatically injected onto the rotating grate. The material is evenly distributed across the grate in order to achieve complete combustion – most of which occurs in suspension, thereby making it possible to significantly vary the loading. When another combustible is used, a separate set of feeders will mechanically inject the extra material onto the grate – with the combustion time optimized according to the granularity of the combustible.
The high pressure drop ensures that combustion air is evenly distributed, ensuring optimal combustion with a reduced amount of excess oxygen.
- The rotating grate spreader-stoker is a proven technology that is both simple and robust. It also leaves little unburned material in the ash.
- Production of CO and NOx is low.
- Overall thermal performance and plant availability are both high.
CNIM can also provide other combustion systems, according to the type of combustible anticipated and its characteristics (mixture of coal and biomass, contaminated biomass etc). These systems include fluidized bed combustion, injection grates and Ignifluid™.
With its proven expertise in the thermal energy and combustion processes, CNIM is able to supply turnkey. As a contractor, CNIM is able to intervene at every stage of a project – from design, manufacture and installation of the equipment.
A boiler for each type of energy recovery
Choosing the type of boiler and its various features depends upon how the energy recovered from biomass is to be used. Recovery can take the form of heat – to provide central heating for households, or steam for industrial use. For solely heat applications, the solution would be a saturated or super-heated boiler, or alternatively a hot-water boiler. The energy can also be transformed into electricity that can be delivered externally in its entirety, or with a small amount of the electricity generated being retained for use by the plant itself. In this case, a boiler producing super-heated steam would provide the greatest amount of energy.
From boiler design and manufacture to installation
From its design studios and workshops at La Seyne-Sur-Mer and Casablanca, Morocco, CNIM designs and manufactures its own elements for a range of different types of waste incineration boilers:
- vertical, horizontal
- floor-standing, suspended
- super-heated or saturated steam
- super-heated water
- convective or radiative superheaters
The Group’s installation teams will deploy the boiler within the biomass co-generation plant itself and then perform testing of steam production before the final consignment to the client. The energy performance of the installed unit is fully guaranteed.
The energy transformed into electricity is delivered externally – except for a small amount of the power generated being retained for use by the plant itself. The particular type and characteristics of the thermal cycle all depend on the use for which the recovered energy is destined. With co-generation, it can also be recovered to provide central heating for households, or steam for industrial use.
Treatment of flue gases by LAB
For energy recovery from biomass, the CNIM subsidiary LAB designs and installs a range of treatment facilities for flue gases:
- removal of nitrogen oxide (DeNOx), whether by catalytic treatment or not
- all types of residue removal, enabling ash to be re-injected into the boiler – thereby reducing the amount of unburned material from the combustion process.
The levels of solid and gas emissions from the plant are well below those permitted by the strictest regulations currently in force.
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