March 21 (Reuters) - Tengizchevroil (TCO), Kazakhstan's liquefied petroleum gas (LPG) producer and exporter, plans to raise propane and butane export through Russian port Taman in 2018 to 450,000 tonnes from 240,000 tonnes in 2017, traders said. TCO's shipments of LPG through Taman port will grow in March to about 40,000 tonnes from 27,000 tonnes in February, traders said. "TCO's LPG export through Taman port will go up to 40,000 from 20,000 tonnes per month (on average in 2017