Abstract: The embodiments herein disclose a method and apparatus for mixing sludge retained in a digester. A jet nozzle assembly for mixing contents of a vessel is used. The jet nozzle assembly having a central outlet pipe terminating at a jet nozzle, a low pressure nozzle assembly disposed concentrically about the central outlet pipe, the low pressure low pressure nozzle having a plurality of openings disposed circumferentially about the low pressure nozzle assembly. The plurality of openings are an axial distance from the outlet jet nozzle.

Abstract: A storage tank includes a tank roof and a tank sidewall. At least one opening is located in in at least one of the tank roof or the tank sidewall. A pipe extends through the at least one opening, the pipe having a sleeve assembly positioned around the pipe. The sleeve assembly also extends through the opening. The sleeve assembly includes a sleeve, at least one layer of insulation, and an inner flange. The inner flange is located on a first end of the sleeve and is coupled to the pipe. The sleeve, in turn is coupled to the tank such that the inner flange is located within the storage tank. The at least one layer of insulation is positioned in an annulus between the pipe and the sleeve.

Abstract: The embodiments herein disclose a method and apparatus for mixing sludge retained in a digester. A jet nozzle assembly for mixing contents of a vessel is used. The jet nozzle assembly having a central outlet pipe terminating at a jet nozzle, a low pressure nozzle assembly disposed concentrically about the central outlet pipe, the low pressure low pressure nozzle having a plurality of openings disposed circumferentially about the low pressure nozzle assembly. The plurality of openings are an axial distance from the outlet jet nozzle.