Process of producing nitric oxide

摘要

In obtaining nitric oxide from gaseous mixtures comprising nitrogen and oxygen by high-temperature heating followed by quenching, the rapid cooling, preferably within 0.1 second, is effected by forcing the highly heated reaction a bed of the above described refractory bodies, which have a mean volume less than that of a sphere of two inches diameter, and accordingly present to the reaction mixture at least 22 square feet of surface area for each cubic foot of volume of the bed. Preferably, the reaction mixture passes serially through a preheating zone, a reaction zone and a chilling zone, the preheating and chilling zones each consisting of a bed of the above described refractory bodies, and the direction of the gases through the system being periodically reversed. The refractory bodies are preferably chaotically assembled and may consist of one of the compounds Al2O3, Cr2O3, ZrO2, ZrO2, SiO2, CaO, MgO, MgO.Al2 O3 (spinel) &c. As shown, a blower 1 forces atmospheric air through a valve 2 and inlet 3 into chamber 4 and from thence through a layer of the refractory bodies 6, the upper layers of which are heated by a prior operation to at least 3400 DEG F., say 4170 DEG F., a reaction space 7, 8, 9 and a layer of the refractory bodies 10, a portion of which has a temperature of say below 300 DEG F., preferably atmospheric temperature, the gas containing nitric oxide leaving chamber 12 via exit 13, valve 2 and pipe 14 to the recovery system. Sufficient fuel oil, natural gas or manufactured gas is introduced into the space 7 through a port 17 to maintain a reaction temperature of, say 4160-4900 DEG F. At chosen intervals valve 2 is rotated through 90 degrees the direction of the gases through the system being thereby reversed. During the reverse flow, the fuel oil &c. is caused to enter the space 9 through a port 19. Operation in a similar apparatus on a smaller scale employing temperatures of 3600-4000 DEG F. is also described. Instead of being empty, the spaces 7, 8, 9 may be filled with relatively large lumps of refractory material.