The present invention provides for a backpack having a pack bag and a modular pack frame. Actual NOx emissions produced by the engine are filtered using a variable NOx time constant in turn correlated to the reductantNOx storage capacity of the reducing catalyst at its current temperature to account for changes in the SCR system attributed to NOx transient emissions. The CO gas-containing gas is subjected to an exothermic reaction in a shift reactor 26 to form H2 and CO2, and the anode gas containing H2 is supplied to an anode 7 of MCFC 2. The detection device detects a portion in which the hue is substantially equal to that of its surrounding portion while brightness is different from that of its surrounding portion as a stain. The process recycles both the water already used in a previous dyeing cycle and all added products that have not been absorbed by the textile substrate, as well as the rest of the disperse dyes that had not been depleted in the previous dyeing cycles.