A system includes a waste heat recovery heat exchanger configured to heat a heating fluid stream by exchange with a heat source in a crude oil associated gas processing plant; and a Kalina cycle energy conversion system including a first group of heat exchangers to heat a first portion of a working fluid by exchange with the heated heating fluid stream and a second group of heat exchangers to heat a second portion of the working fluid. The second group of heat exchangers includes a first heat exchanger to heat the second portion of the working fluid by exchange with a liquid stream of the working fluid; and a second heat exchanger to heat the second portion of the working fluid by exchange with the heated heating fluid stream. The energy conversion system includes a separator to receive the heated first and second portions of the working fluid and to output a vapor stream of the working fluid and the liquid stream of the working fluid; a first turbine and a generator to generate power by expansion of the vapor stream; and a second turbine to generate power from the liquid stream.