Projection Inc., an audiovisual and computer equipment rental company, has named Thomas Mitchem manager of its Washington office. Mitchem, who has been a meeting planner with an association in Detroit, replaces Jim Karson, who has been appointed director of customer services for national accounts.

Towers, Perrin, Forster & Crosby, an international management consulting firm, has named Alan H. Dugan manager of its Washington office. Dugan, a vice president, most recently was manager of the firm's Minneapolis office. He succeeds John W. Fisher, who will retire in January.

Washington architect Douglas E. Deremer has been named regional vice president of the design division at Interspace Inc., a local design and architectural firm. Deremer, whose Washington design projects have included the award-winning Riggs Library at Georgetown University and Bell Atlantic's regional headquarters in Arlington, formerly was principal-in-charge of the Washington office of EPR Inc., a national interior design firm. He will share management responsibilities with Interspace's office manager, George C. Tooop Jr.

Touche Ross & Co., one of the "big eight" accounting firms, has named John T. Connor, the director of its Washington Service Center, to play a major role in the firm's management as associate managing partner under Edward A. Kangas, who recently was named managing partner. Connor, who will remain director of the government liaison office, will have additional responsibility for eight Touche Ross offices in the Washington area and the Midwest.

The Weihe Partnership announced three appointments: Mark Bellonby has been named a partner; Marc Nathanson has been named director of architectural coordination, and Jeffrey A. Morris has been appointed an associate.