A method of preventing blockage of circulating bed material in a circulating fluidized bed reactor includes collecting a continuously flowing bed of solid particles in a gas lock in a return leg of a reactor, measuring gas lock bed pressure values within the bed of the particles, generating a gas lock bed height indication signal on the basis of measured gas lock bed pressure values. A definition stage includes defining and storing to a control system a range of normal gas lock bed height indication signals, formed in normal circulation flow conditions, as a function of the reactor load, and defining and storing to the digital control system a reactor load dependent alarm criterion. The method includes comparing a current gas lock bed height indication signal with the reactor load dependent alarm criterion, and decreasing the reactor load if the current indication signal fulfils the reactor load dependent alarm criterion.

A system includes a standpipe for receiving a flow of solids therethrough, the standpipe having at least one inlet configured to receive a gas for decreasing a solids-to-gas ratio of the flow, a sealpot having an inlet fluidly coupled to the standpipe and an outlet fluidly coupled to a riser, the sealpot being configured to fluidize the solids received from the standpipe and to transport the solids to the riser, and a drain device fluidly coupled to an outlet in the standpipe, the outlet being located upstream from the inlet of the sealpot. The drain device is configured to remove the excess gas from the flow of solids within the standpipe to increase the solids-to-gas ratio of the flow prior to the solids entering the sealpot.

An apparatus for controlling flow of a material includes an inlet for receiving the material from a source, and a seal mechanism connected to the inlet, the seal mechanism having a fluidizing bed configured to receive the material from the inlet, a first discharge passageway and a second discharge passageway. The fluidizing bed includes a first transport zone associated with the first discharge passageway and a second transport zone associated with the second discharge passageway, wherein the first and second transport zones are configured to receive transport gas from a transport gas source. The transport gas is controllable to selectively divert a flow of the material into the first discharge passageway and the second discharge passageway.

An apparatus for controlling flow of a material includes an inlet for receiving the material from a source, and a seal mechanism connected to the inlet, the seal mechanism having a fluidizing bed configured to receive the material from the inlet, a first discharge passageway and a second discharge passageway. The fluidizing bed includes a first transport zone associated with the first discharge passageway and a second transport zone associated with the second discharge passageway, wherein the first and second transport zones are configured to receive transport gas from a transport gas source. The transport gas is controllable to selectively divert a flow of the material into the first discharge passageway and the second discharge passageway.

A system includes a standpipe for receiving a flow of solids therethrough, the standpipe having at least one inlet configured to receive a gas for decreasing a solids-to-gas ratio of the flow, a sealpot having an inlet fluidly coupled to the standpipe and an outlet fluidly coupled to a riser, the sealpot being configured to fluidize the solids received from the standpipe and to transport the solids to the riser, and a drain device fluidly coupled to an outlet in the standpipe, the outlet being located upstream from the inlet of the sealpot. The drain device is configured to remove the excess gas from the flow of solids within the standpipe to increase the solids-to-gas ratio of the flow prior to the solids entering the sealpot.

A fluidized bed gasification system which comprises a fluidized bed gasification reactor having a bottom ash discharge outlet below the reactor, wherein an L-valve is used to control the rate of bottom ash discharge. The L-valve uses an aeration port located on distal side of the L-valve vertical pipe at a location that is above the center line of the horizontal pipe. Also provided are methods of controlling the bottom ash discharge as well the fluidized reaction bed height of the system.

A fluidized bed gasification system which comprises a fluidized bed gasification reactor having a bottom ash discharge outlet below the reactor, wherein an L-valve is used to control the rate of bottom ash discharge. The L-valve uses an aeration port located on distal side of the L-valve vertical pipe at a location that is above the center line of the horizontal pipe. Also provided are methods of controlling the bottom ash discharge as well the fluidized reaction bed height of the system.

A method of preventing blockage of circulating bed material in a circulating fluidized bed reactor includes collecting a continuously flowing bed of solid particles in a gas lock in a return leg of a reactor, measuring gas lock bed pressure values within the bed of the particles, generating a gas lock bed height indication signal on the basis of measured gas lock bed pressure values. A definition stage includes defining and storing to a control system a range of normal gas lock bed height indication signals, formed in normal circulation flow conditions, as a function of the reactor load, and defining and storing to the digital control system a reactor load dependent alarm criterion. The method includes comparing a current gas lock bed height indication signal with the reactor load dependent alarm criterion, and decreasing the reactor load if the current indication signal fulfils the reactor load dependent alarm criterion.