Abstract: Direct steam injection (DSI) heating techniques can use a heater to heat a process stream in bitumen froth treatment. The DSI heater can include a diffuser with multiple side-by-side rows of outlets perpendicular to a longitudinal axis of the diffuser, and a piston plug that moves axially within the diffuser to selectively cover rows of outlets to vary steam injection. The piston plug has first and second annular seals and is moved between different axial positions in a stepwise fashion such that when one or more rows of outlets are completely covered, the first annular seal is located in between adjacent rows and the second annular seal abuts against the diffuser to inhibit passage of steam so as to prevent cavitation. The DSI heater can include various other features, such as particular seal unit constructions and diffuser outlet configurations.

Abstract: Direct steam injection (DSI) heating techniques can use a heater to heat a process stream in bitumen froth treatment. The DSI heater can include a diffuser with multiple side-by-side rows of outlets perpendicular to a longitudinal axis of the diffuser, and a piston plug that moves axially within the diffuser to selectively cover rows of outlets to vary steam injection. The piston plug has first and second annular seals and is moved between different axial positions in a stepwise fashion such that when one or more rows of outlets are completely covered, the first annular seal is located in between adjacent rows and the second annular seal abuts against the diffuser to inhibit passage of steam so as to prevent cavitation. The DSI heater can include various other features, such as particular seal unit constructions and diffuser outlet configurations.

Abstract: Direct steam injection (DSI) heating techniques can use a heater to heat a process stream in bitumen froth treatment. The DSI heater can include a diffuser with multiple side-by-side rows of outlets perpendicular to a longitudinal axis of the diffuser, and a piston plug that moves axially within the diffuser to selectively cover rows of outlets to vary steam injection. The piston plug has first and second annular seals and is moved between different axial positions in a stepwise fashion such that when one or more rows of outlets are completely covered, the first annular seal is located in between adjacent rows and the second annular seal abuts against the diffuser to inhibit passage of steam so as to prevent cavitation. The DSI heater can include various other features, such as particular seal unit constructions and diffuser outlet configurations.

Abstract: Direct steam injection (DSI) heating techniques can use a heater to heat a process stream in bitumen froth treatment. The DSI heater can include a diffuser with multiple side-by-side rows of outlets perpendicular to a longitudinal axis of the diffuser, and a piston plug that moves axially within the diffuser to selectively cover rows of outlets to vary steam injection. The piston plug has first and second annular seals and is moved between different axial positions in a stepwise fashion such that when one or more rows of outlets are completely covered, the first annular seal is located in between adjacent rows and the second annular seal abuts against the diffuser to inhibit passage of steam so as to prevent cavitation. The DSI heater can include various other features, such as particular seal unit constructions and diffuser outlet configurations.