This invention relates to a three return travel half 
coal, oil and gas fuel smokelessness boiler. It includes boiler external cylinder, inner bag shell, multiple horizontal siphonal areas, water cold wall 
pipe, and combination furnace arch and fire grate. Its feature is that annular secondary air 
bellows and arched first air 
bellows are fixed under fire grate, the secondary air bellow is interconnected to vertical quadric air manifold set along furnace outer wall, semilunar horizontal air 
pipe is set under arched high temperature fume outlet at both sides of furnace. The combination furnace arch is consisted by yi form up furnace arch, inverse L form middle arch and concave down arch. The three arches are all formed by combination of horizontal cleet water cover and vertical cleet water cover and plugging cleet water cover connecting through fire bricks, and malpositioned in inner bag shell, three return travel 
flue is formed under up furnace arch. Both sides of up parts of inner bag shell shrink entad to form two segment special form 
barrel of vertical upright faces. Up part horizontal 
pipe is put up between two vertical upright faces. 
Bituminous coal smokelessness burning technique and inner furnace 
smoke prevention and 
dust control technique is formed by the boiler in this invention and air distribution burning technique and multifunction furnace arch structure. 
Coal cleanliness burning smokelessness boiler is formed by the combination of 
bituminous coal smokelessness burning technique and three return half 
coal process. Its heat efficiency is high when running longtime, energy saving effect is great, discharging of polluting matter is low, and the oil and gas fuel boiler is achieved.