Pyrolysis reactor materials and methods
In one aspect, the invention includes a reactor apparatus for pyrolyzing a hydrocarbon feedstock, the apparatus including: a reactor component comprising a refractory material in oxide form, the refractory material having a melting point of at least 2060° C. and which remains in oxide form when exposed to a gas having an oxygen partial pressure of 10 −15 bar, a carbon partial pressure above the carbon partial pressure of the zirconium carbide and zirconium oxide phase transition at the same temperature, and at temperatures below the temperature of the zirconium triple point at the oxygen partial pressure of 10 −15 bar; and ii) when exposed to a gas having an oxygen partial pressure of 10 −15 bar and at temperatures above the zirconium triple point at the oxygen partial pressure of 10 −15 bar. In some embodiments, the reactor comprises a regenerative pyrolysis reactor apparatus and in other embodiments it includes a reverse flow regenerative reactor apparatus. In other aspects, this invention includes a method for pyrolyzing a hydrocarbon feedstock using a pyrolysis reactor system comprising the step of providing in a heated region of a pyrolysis reactor system for pyrolyzing a hydrocarbon feedstock, apparatus comprising the above refractory material.
1. A method for pyrolyzing a hydrocarbon feedstock using a pyrolysis reactor system comprising the steps of:
(A) heating a region of the pyrolysis reactor system, the region including at least one refractory material in oxide form, and the region being heated by flowing at least one reactant in a first direction through the reactor system and reacting the at least one reactant within the reactor system;
wherein the refractory material has a melting point of no less than 2060° C.;
wherein the refractory material remains in oxide form during at least one of the following two scenarios:
i) when the refractory material is exposed to both (a) a first temperature in the presence of a gas having an oxygen partial pressure of 10 −15 bar and a carbon partial pressure above that exhibited by zirconium carbide at the zirconium carbide's phase transition to zirconium oxide at the first temperature, and (b) a second temperature in the presence of a gas having an oxygen partial pressure of 10 −15 , the second temperature being below that of zirconium's triple point; and
ii) when exposed to a temperature in the presence of a gas having an oxygen partial pressure of 10 −15 bar, the temperature being above that of zirconium's triple point; and
wherein the refractory material includes
(i) at least 20 wt. % of a first grain mode based upon the total weight of the refractory material, the first grain mode comprising yttria and having a D50 grain size in the range of from 5 to 2000 μm; and
(ii) at least 1 wt. % of a second grain mode based upon the total weight of the refractory material, the second grain mode comprising yttria and having a D50 grain size in the range of from 0.01 μm up to not greater than one-fourth the D50 grain size of the first grain mode;
(B) introducing a hydrocarbon feedstock into the heated region; and
(C) pyrolyzing the hydrocarbon feedstock using heat from the heated region.
2. The method of claim 1 , wherein the refractory material remains in oxide form when exposed to a gas having a carbon partial pressure of 10 −11 bar, an oxygen partial pressure of 10 −15 bar, at a temperature of 2050° C.
3. The method of claim 1 , wherein,
during step (A) the heated region is heated to a temperature of no less than 1200° C.
4. The method of claim 1 , wherein the refractory material remains in the oxide form when exposed to a gas having a carbon partial pressure of 10 −10 bar, an oxygen partial pressure of 10 −15 bar, and at a temperature over the full range of from 1800° C. to 2100° C.
5. The method of claim 1 , wherein the refractory material comprises 80 wt.% yttria based upon the total weight of the refractory material.
6. The method of claim 1 , wherein the refractory material comprises 90 wt.% yttria based upon the total weight of the refractory material.