DIARY-U.S. refinery operations-Motiva Port Arthur, Texas alky unit ops normal after work

July 21 (Reuters) - The following is a list of refinery incidents reported in the United States on July 20: * Motiva's Port Arthur, Texas alky unit ops normal after work -sources * Total's Port Arthur, Texas refinery naphtha hydrotreater restarts: sources * Total Port Arthur refinery restarts reformer -sources * Valero Three Rivers, Texas refinery reports flaring on July 19