Optimising fuel flow in pulverised coal

Transcription

1 Optimising fuel flow in pulverised coal and biomass-fired boilers Dr Malgorzata (Maggie) Wiatros-Motyka 11 th ECCRIA 5-7 September 2016, Sheffield, UK

2 Why optimise fuel flow Improve plant efficiency Reduce emissions Reduce maintenance Lower operating costs Eliminate safety hazards Increase fuel flexibility

3 Opportunities for improvement OFA Verification: Temperature O 2, CO, NOx LOI Coal and air flow to individual burners Air/fuel ratio and fuel distribution Coal feed rate to mills and fuel fineness *Image: modified from Combustion Technologies/ AMC Power Secondary air Primary air

4 Optimisation starts in the mill *Image: Storm Technologies Inc.

5 Coal fineness measurement Fuel fineness requirement: 75% passing 74 µm and 0.1% retained on 294 µm Traditional manual sampling versus advanced techniques Important factors (sampling location, representative sample sampling all lines of each mill, analysis time)

6 Mill optimisation Keeping all elements in good condition Keeping the distance and balancing the load Setting the correct throat clearance Maintaining the classifier *Images: Storm Technologies Inc.

7 Air flow measurements All air flows (PA, SA, OFA) need to be measured and controlled Accurate measurements of combustion air streams are not easy Traditional versus advanced measurement New technologies range from advanced pitot tubes through electrostatic based systems to virtual and optical sensors Images: Verabar from Mid-West Instrument

8 Fuel flow measurement and control Fuel always takes the easiest route available Accurate, real-time measurements are an important prerequisite to optimal fuel distribution Traditional manual isokinetic sampling is still dominant in majority of power plants despite the fact that this type of measurement is the least accurate from currently avaible systems Images: top PROMECON s MECONTROL Coal, bottom Greenbank s PF Master

9 Fuel flow measurement Advanced flow measurement instruments are based on a number of techniques (electrostatic and cross correlation, microwave, laser, acoustic emission) When choosing appropriate technology many factors need to be taken into account Differences in applications for coal and biomass-fired (cofiring) boilers Images: top PROMECON s MECONTROL Coal, bottom Greenbank s PF Master

10 Fuel flow control Flow distribution and rope breaking devices when combined with control elements are able to break the rope and then control, balance and trim air/fuel ratio to desired distribution down each pipe leg Manufacturers offer customised products created with computational fluid dynamic models for existing PF distribution systems Can be controlled manually or remotely Images: top Greenbank s VARB, bottom Combustion Technologies NT Diffusing Valve

11 Verification of fuel flow optimisation Carbon in ash, O 2, CO (and other) measurements can be useful Carbon in ash, O 2, CO (and other) measurements can be useful tools leading to adjustment, control and air/fuel flow optimisation

12 Case studies - typical gains Improvements in efficiency Emission reduction Fuel cost savings Fuel flexibility Increased sale of fly ash Elimination i of safety hazards Improved performance of emission control equipment

13 Key Messages Fuel flow optimisation offers significant benefits for both coal and biomass-fired boilers New, advanced d technologies are more accurate than traditional ones and yield greater benefits When choosing appropriate technology many factors need to be taken into account Optimisation results depend highly on the pre-optimisation conditions and are very case specific If you cannot measure, you cannot control. If you cannot control, you cannot optimise (F. Turoni)

14 Thank you

15 The 8th international conference on clean coal technologies Cagliari, Sardinia, 8-12 May High efficiency plant Carbon capture Pollutant control Biomass cofiring Gasification and coal to X Lignite utilisation High-temperature materials Policy and financing Call for abstracts next week