What do you suggest to remove glue and carpet remnants from a concrete porch? The old carpet was loose in some areas and also very worn, it had been down for about 15 years. We pulled the carpet up, but was left with the glue and remnants of carpet. I have been told to use denatured alcohol or muric acid. We tried a pressure washer, but it would take days and gallons of water. If you have had this problem and found a solution, I would appreciate your comments.
After I remove the glue, I would like suggestions as to what type of tile to use on the porch

If it's a small area a good old fashion scraper with elbow grease you can get a pole scraper there's many types for a large area you can rent a buffer/floor sander you would still need to scrape it down some but the sander will get it to the ready point.

Scraper yes but not a sander , it will just plug up I, ediately. After scraping what you can try using a commercial adhesive remover like Sentinel 626 - Carpet and Sheet Vinyl Adhesive Remover (http://www.installerstore.com/catalog/Sentinel-626-Carpet-and-Sheet-Vinyl-Adhesive-Remover-p-1792.html)

Well if you are outside, a pressure washer ( the right size and type) will take the top layer of concrete off if you wanted to.

3000 to 4000 PSI with heated water to about 280 egree and 4 to 5 gallon a minute. I would use a turbo nozzle

It would be clean as fast as you could wash it over normally.

A citrus based cleaner will help get rid of any sticky residue