Method for preparing porous sludge fuel

The invention discloses a method for preparing porous sludge fuel. The method comprises the following steps: conveying and flattening sludge; gradually upgrading and extruding; performing high-pressure extrusion forming; pressure maintaining and pore forming; the porous sludge fuel is prepared in a pure mechanical extrusion mode, a mechanical extrusion slow pressurization mode is matched, an extrusion section adopts a rigid interface, it is guaranteed that all positions of the sludge can be subjected to uniform extrusion pressure after the sludge is separated from a plastic interval, and water in the sludge is gradually stripped; meanwhile, high-pressure extrusion is carried out in combination with relatively high pressure to further remove moisture, and the moisture of the sludge is removed under the dual action of gravity and pressure by virtue of vertical extrusion and high-pressure holding extrusion means, so that pores are formed in a sludge cake, and the sludge has relatively high mass transfer and heat