General Electric Co. is launching a mobile device aimed at helping natural gas drillers recycle water used in a controversial gas drilling process known as hydraulic fracturing. The truck-sized, transportable device would cut down on both the amount of fresh water used and wastewater currently trucked long distances for disposal. The company’s mobile evaporator would allow natural gas producers to reuse some of the millions of gallons of water used to extract natural gas from dense shale deposits deep underground through the so-called “fracking” process. Water is mixed with chemicals and sand and pumped at high pressure thousands of feet...