Modular flare stack and method of flaring waste gas

A modular flare stack for enclosed flame combustion of a combustible fluid, comprising:

• a gas feed pipe;
• and
• at least two burner elements configured to combust the combustible fluid,
• wherein said gas feed pipe comprises a gas pressure detector configured to measure pressure of waste or process gas,
• wherein each of the at least two burner elements is equipped with means for obtaining a fully premixed air-fuel mixture,
• wherein the each of the at least two burner elements comprises:
• a gas inlet,
• a gas permeable combustion surface,
• a mixing chamber, and
• a combustion chamber,
• wherein said gas inlet of the each of the at least two burner elements is adapted to receive the combustible fluid from said gas feed pipe,
• wherein the each of the at least two burner elements comprises a temperature detector configured to measure flue gas temperature,
• wherein the each of the at least two burner elements comprises an air-excess modulator for its respective mixing chamber,
• wherein said modular flare stack further comprises a controller configured to be responsive to said gas pressure detector, to be responsive to said temperature detectors, and to control said air-excess modulators, and
• wherein the each of the at least two burner elements further comprises a vertically movable insulated stack and the gas permeable combustion surface of the each of the at least two burner elements is replaceable for easy maintenance.