YYQ(W) fuel gas thermal oil boiler is a high-tech energy-saving and environmentally friendly product developed by our company. The boiler body adopts the spiral close-packed coil structure, and the double-layer or multi-layer spiral close-packed coils form the heating surface. The inner-ring coil is the combustion radiation heat exchange surface, and the gap between the inner-ring coil and the middle-ring coil or the outer-ring coil constitutes the hot flue gas heat exchange surface. The dense arrangement of the multi-layer coils and the shell form a flue gas three-return structure, the space heat exchange intensity is optimized, the convection heat exchange is strengthened, and the heating surface is sufficient to ensure the output and thermal efficiency of the boiler. The large furnace design not only ensures the full combustion of the fuel but also meets the environmental protection and low nitrogen emission requirements.