Method for the continuous thermal hydrolysis of sludge with a high dryness value

A plant for continuously thermally hydrolyzing sludge comprising:

• a. means for conveying sludge to be treated;
• b. a dynamic mixer having a rotor configured to rotate 1500-4000 rpm;
• c. said dynamic mixer configured to receive the sludge and to de-structure the sludge and produce a homogeneous de-structured sludge;
• d. a heat exchanger located downstream from the dynamic mixer and comprising an inlet configured to receive said homogeneous de-structured sludge from the dynamic mixer and an outlet for discharging heated homogeneous de-structured sludge;
• e. a thermal hydrolysis reactor located downstream of said heat exchanger and including an inlet for receiving the heated homogeneous de-structured sludge produced by the heat exchanger;
• f. means for recirculating said hydrolyzed sludge to a hydrolyzed sludge inlet associated with the heat exchanger such that the heat exchanger is a sludge-to-sludge heat exchanger that effectively cools the thermally hydrolyzed sludge;
• and
• g. a dynamic injector-mixer located downstream of said heat exchanger, and wherein said dynamic injector-mixer is configured to receive the homogeneous de-structured sludge produced by said heat exchanger;
• and wherein said dynamic injector-mixer further comprises a steam inlet for receiving steam and an outlet for discharging a homogenous mixture of heated de-structured sludge.

A method for continuous thermal hydrolysis of dehydrated sludge containing organic matter, the method comprising:

• a. subjecting the dehydrated sludge having a dry solids content exceeding 20% (wt.) to a sludge de-structuring process and mechanically de-structuring the sludge and reducing the viscosity of the sludge and in the process forming a fluidized homogeneous de-structured sludge;
• b. wherein mechanically de-structuring the sludge comprises:
• i. directing the sludge into a dynamic mixer comprising a chamber having a rotor;
• ii. injecting steam into the dynamic mixer and driving the rotor at a speed of 1500-4000 rpm;
• c. directing the homogenized de-structured sludge from the dynamic mixer into and through a sludge-to-sludge heat exchanger and heating the homogenized de-structured sludge;
• d. directing the heated homogenized de-structured sludge from the heat exchanger to a thermal hydrolysis reactor and thermally hydrolyzing the sludge;
• and
• e. directing the thermally hydrolyzed sludge back to and through the sludge-to-sludge heat exchanger where the thermally hydrolyzed sludge heats the homogenized de-structured sludge produced by the dynamic mixer.