Artist Kenneth Noland, the Washington Color Painter who moved away from Washington 20 years ago, yesterday returned to acknowledge an old debt.

Noland came to town to express his deep affection for--and, though he did not push it, to encourage contributions to--the Phillips Collection, the widely loved museum whose extraordinary paintings helped him find his way to his innovative art.

"I've spent many hours of many days in this . . ."--he fumbled for the word--". . . in this home," he said. "It is a home, a home of art. You can be with art in the Phillips as in no other place I know. It was very important to me, and to my fellow artists. We used it as a meeting place . . ." Noland paused again. He looked up at his audience, and at the old abstractions by Augustus Vincent Tack hanging on the walls of the museum's music room. "These were the only Tacks we were privileged to see," he said. "We talked about them a lot." Noland spoke as well about other Phillips pictures that had moved him long ago--the Averys, the Doves, "that beautiful little Ryder."

"There are so many things that I could say, but I get embarrassed," said the now-famous painter. "Welcome to a wonderful place."

Laughlin Phillips and erudite, amusing Joseph Alsop also addressed the 80 guests attending "Behind the Scenes at the Phillips Collection," a day-long party of a sort held to help raise funds for the world's first museum of modern art, which Laughlin's father, Duncan, opened to the public in his home on 21st Street NW more than 60 years ago.

The Phillips surely is the most intimate and charming of Washington's art museums. It may also be the most influential. Washington Color Painting, as Noland's presence there yesterday suggested, might never have developed if the late Duncan Phillips, a man in love with color, had not chosen to display his daring modern paintings, his Cezannes and his Tacks, his Bonnards and his Klees, here among the grids, chevrons and circles of Pierre L'Enfant's city plan.

Though Duncan Phillips at his death in 1966 left his family's museum a $3 million endowment, the Phillips now needs cash. Its wiring is old, its heating system antique, and many of its 2,500 pictures are in need of restoration. In 1979, Laughlin Phillips, now the museum's director, organized a fund drive whose aim it is to raise at least $5 million. Yesterday he said he is half way to his goal.

The art fans, collectors and potential benefactors at yesterday's soft-sell party were given lunch and lectures, tours of the collection--and a bit of news.

The Phillips, they were told, is organizing exhibitions devoted to the art of two of Duncan Phillips' favorite painters. A Morris Graves show will open there next year. The museum, in cooperation with the Centre Pompidou in Paris, also is arranging a retrospective of the art of Pierre Bonnard (1867-1947). It will open in Paris in 1984, before coming here.

Two paintings that the guests were shown made clear the depth of Kenneth Noland's debt to Duncan Phillips' eye. One, a playful picture filled with wavy lines, Xs, dots and dashes, is a painting called "Young Moe," which Paul Klee completed in 1938. The other, "In the Garden," a 30-year-old Noland, seems a version of the Klee done in happy shades of red.

They also looked at "April," a little 1960 Noland whose concentric bands of color call to mind the "targets" that would later earn him fame.

In introducing Joseph Alsop, Laughlin Phillips said the former columnist "is in some respects as much of a Washington institution as is this collection."

Alsop, who observed that collecting had developed independently in Greece, Rome, China, the Islamic world, Italy--and nowhere else--touched on subjects as diverse as the flea collection of a British Baron Rothschild, the Ark of the Covenant, the Raphael forgery by Andrea del Sarto, and the use of boiled billy goats for the softening of gems.

When collector David Lloyd Kreeger asked him to discuss the fake Vermeers painted by Han Van Meegeren, Alsop instead spoke about a forger he knows, "a gifted, jolly Chinaman, now perhaps 82.

"There is not one single museum with a Chinese collection that doesn't have a specimen of his work," said Alsop. "He also has a superb chef. And I believe he has just acquired a new concubine."