A pyrolysis reactor for processing municipal and domestic wastes comprising: a pyrolysis chamber, a loading mechanism (44, 46, 52, 54) that includes a waste accumulator and two gates (44, 46) coupled to the pyrolysis chamber via a feeding screw for loading the pyrolysis chamber with wastes without access of oxygen to the pyrolysis chamber, an unloading mechanism (44, 46,52,54) that includes a waste accumulator and gates (44, 46) coupled to the pyrolysis chamber for unloading the pyrolysis chamber from solid residual products of pyrolysis without access of oxygen to the pyrolysis chamber, the pyrolysis chamber comprising: an inlet device, an outlet device, and a three-lobe retort comprising an elongated horizontally arranged hollow body having two lower parallel and substantially cylindrical lobes (36a, 36b) and an upper syngas guiding chamber with vertical walls (36d, 36e); two waste-feeding screws (40,42) that have threads(40a, 42a) with outer surfaces and are located in said lobes, respectively, the two screws (40, 42) being tapered in shapes with a taper angle that decreases the diameters of the waste-feeding screws (40, 42) from said inlet device to said outlet device, and the waste-feeding screws (40, 42) having a gap between their outer surfaces, wherein the two waste-feeding screws (40, 42) converge towards each other from the inlet device to the outlet device with a convergence angle and the threads (40a, 42a) of the two waste-feeding screws (40, 42) overlapping each other without physical contact and leave a space between the helical surfaces of the threads (40a, 42a). a pyrolysis chamber, a loading mechanism (44, 46, 52, 54) that includes a waste accumulator and two gates (44, 46) coupled to the pyrolysis chamber via a feeding screw for loading the pyrolysis chamber with wastes without access of oxygen to the pyrolysis chamber, an unloading mechanism (44, 46,52,54) that includes a waste accumulator and gates (44, 46) coupled to the pyrolysis chamber for unloading the pyrolysis chamber from solid residual products of pyrolysis without access of oxygen to the pyrolysis chamber, the pyrolysis chamber comprising: an inlet device, an outlet device, and a three-lobe retort comprising an elongated horizontally arranged hollow body having two lower parallel and substantially cylindrical lobes (36a, 36b) and an upper syngas guiding chamber with vertical walls (36d, 36e); two waste-feeding screws (40,42) that have threads(40a, 42a) with outer surfaces and are located in said lobes, respectively, the two screws (40, 42) being tapered in shapes with a taper angle that decreases the diameters of the waste-feeding screws (40, 42) from said inlet device to said outlet device, and the waste-feeding screws (40, 42) having a gap between their outer surfaces, wherein the two waste-feeding screws (40, 42) converge towards each other from the inlet device to the outlet device with a convergence angle and the threads (40a, 42a) of the two waste-feeding screws (40, 42) overlapping each other without physical contact and leave a space between the helical surfaces of the threads (40a, 42a). an inlet device, an outlet device, and a three-lobe retort comprising an elongated horizontally arranged hollow body having two lower parallel and substantially cylindrical lobes (36a, 36b) and an upper syngas guiding chamber with vertical walls (36d, 36e); two waste-feeding screws (40,42) that have threads(40a, 42a) with outer surfaces and are located in said lobes, respectively, the two screws (40, 42) being tapered in shapes with a taper angle that decreases the diameters of the waste-feeding screws (40, 42) from said inlet device to said outlet device, and the waste-feeding screws (40, 42) having a gap between their outer surfaces, wherein the two waste-feeding screws (40, 42) converge towards each other from the inlet device to the outlet device with a convergence angle and the threads (40a, 42a) of the two waste-feeding screws (40, 42) overlapping each other without physical contact and leave a space between the helical surfaces of the threads (40a, 42a).