The title problem has comprehensively been summarized and evaluated

pointing out that the "W"shaped flame boilers are roughly suitable for lean coals with V daf =10%-15%

which are comparatively difficult to catch up fire and burn-up

among them coals of medium flammability can still use conventional combustion method; It is necessary to avoid mixed burning of coal sorts with quite different behavier

in the case of no choice but to blend some coal sorts

attention must be paid specially to the design and commission debugging of the combustion system and it’s related equipments; It is considered that the research of different combustion techniques for low volatile coals must be strengthened at present

paying attention to the perfection of "W"shaped flame boilers

the research of combustion technology for mixed burning different coal sorts

as well as boilers with liquid ash disposal and low No x emmision

so as to meet the varied requirements of burning low volatile coals.