Ditto the Spirax Sarco reference: Up until very recently, you used to be able to download the entire spirax sarco book in pdf. It is still available on the website in html, and can be ordered in book form. A very useful, practical guide.
The often cited, big "Steam:its generation and use" book from babcock and wilcox is very detailed on the equipment side and dials down to process requirements for specific applications.