The Ash Vessel System operates on the principle of Dense Phase Pneumatic Conveying, i.e. a high pressure, dense material air mixture at a low velocity moving through the conveying pipe in separate batches or plugs. The Ash Vessel comprises one piece body with a top inlet aperture and horizontal inlet and outlet aperture for conveying material. Mounted on the top inlet is a specially designed Macawber Beekay Dome Valve. It has a controlled air supply for conveying the material.

The Dome Valve is a pressure tight valve. It comprises of a cast iron body, a movable part spherical dome, support shafts and bearing, and integral inflatable synthetic rubber seal, a pneumatic cylinder actuator and an air limit switch to operate the inflatable seal. The air limit switch is arranged such that the dome must be closed before the seal can be inflated, the seal being deflated before the dome is opened. The inflatable seal is so arranged that it closes tightly on to the outside face of the dome thus providing an air tight seal into the valve body.

The basic operation of Ash Vessel is as follows:

The Dome valve is normally closed, when material transfer is required, the Dome valve opens and allows the material to be vessel filled in Dome valve closes through timer, and the pneumatic seal inflates against the Dome and at the same instant the vessel is pressurized by high pressure of air, material resistance causes a pressure build-up in the vessel which conveys the complete charge to the storage bunker or silo. When conveying is completed the pressure drops down to near atmospheric pressure and is sensed by the control system, the air supply to the vessel is stopped and the Dome valve opens to accept the next charge of material, on the command from level probe/timer.

The Ash vessel is used where material from number of hoppers is collected in different ash vessels and is conveyed through a single pipeline. All the ash vessels are connected in series have independent dome valve, but the conveying air is controlled by first vessel i.e. called Master Vessel. The other vessels are called Slave Vessels.