The ornamental design for a portable firepit with propane burner, as shown and described.
FIG. 1 is a front view of a portable fire pit with propane burner;
FIG. 2 is a right side view thereof,
FIG. 3 is a left side view thereof;
FIG. 4 is a top view thereof;
FIG. 5 is a bottom view thereof;
FIG. 6 is an isometric view thereof,
FIG. 7 is front view in a condition of use; and,
FIG. 8 is a detailed view of FIG. 1.
Unclaimed cut through art and cut through text shown in FIGS. 1-3, and 6-7 are drawn in dashed lines. An unclaimed gas burner shown in FIGS. 4 and 6 is drawn in dash dot lines. An unclaimed cut through line shown in FIGS. 4, 5, and 6 is drawn in dashed lines. Unclaimed exterior perimeter latches shown in FIGS. 1-7 are drawn in dashed lines. An unclaimed propane tank and line shown in FIG. 7 are drawn in dashed lines. The dashed lines and dash dot lines shown in FIGS. 1-7 are for purposes of illustrating environmental structure associated with the claimed design in condition of use, and which forms no part of the claimed design.