Short answers, pulled from the story.
James Beaumont Neilson invented the hot blast system at Wilsontown Ironworks in Scotland during 1828. He secured a patent for this method on the 1st of January 1828 with partners including Charles Macintosh.
Neilson cut fuel consumption from 8.06 tons of coal down to 5.16 tons per ton of produced iron by raising the temperature of incoming air. This discovery formed the basis for a new system of preheating blast that significantly reduced costs.
Dr Frederick W Gessenhainer produced a small quantity of anthracite iron by this method at Valley Furnace near Pottsville Pennsylvania in 1836. He filed for a US patent on the 5th of February 1836 regarding hot blast and anthracite before his death in 1838.
In south Staffordshire alone 42 of 80 furnaces adopted hot blast usage by 1843. By 1840 only 58 ironmasters had taken out licenses for the process generating royalty income totaling £30,000 per year.
The Cowper stove is a regenerative heat exchanger that preheats incoming blast air with waste heat from flue gas for modern blast furnaces. The Siemens Martin open hearth furnace also applied this same principle for making steel.