Have you checked the Library of Congress for books written about the Orphanage or books in which the Orphanage is mentioned prior to its burning? Someone at the Library of Congress might be able to help you think of ways to look for information pertaining to this orphanage.

Also, I would try the National Archives in Washington D.C.
You would be amazed at the number of archives in which information is stored.

I did not know where my father came from. But the Old Civil and Military Records archives had a copy of his permit to sail in American waters which led to much needed information.