METHOD OF AT LEAST PARTLY CALCINING A RAW MATERIAL IN A PROCESS OF PRODUCING A CEMENTITIOUS MATERIAL
A method of at least partly calcining a raw material in a process of producing a cementitious material, includes providing a first calcination device that is heated by a plasma torch ejecting a plasma jet, introducing a flow of raw material into the first calcination device, at least partially calcining the raw material in the first calcination device, wherein a first flow of a CO 2 rich gas containing at least 60 vol.-% CO 2 is fed to the plasma torch as a carrier gas for generating the plasma jet, and wherein a second flow of a CO 2 rich gas containing at least 60 vol.-% CO 2 is mixed with the plasma jet in order to adjust the temperature and/or the shape of the plasma jet.
1 . A method of at least partly calcining a raw material in a process of producing a cementitious material, comprising:
providing a first calcination device that is heated by means of a plasma torch ejecting a plasma jet,
introducing a flow of raw material into the first calcination device,
at least partially calcining the raw material in the first calcination device,
wherein a first flow of a CO 2 rich gas containing at least 60 vol.-% CO 2 is fed to the plasma torch as a carrier gas for generating the plasma jet, and
wherein a second flow of a CO 2 rich gas containing at least 60 vol.-% CO 2 is mixed with the plasma jet in order to adjust the temperature and/or the shape of the plasma jet.
2 . The method according to claim 1 , wherein the flow of raw material is fed into the plasma jet in order to provide a direct heating of the raw material.
3 . The method according to claim 1 , wherein the flow of raw material is introduced into the calcination device by being entrained by the plasma jet.
4 . The method according to claim 1 , wherein the CO 2 rich gas of the first flow and/or of the second flow of CO 2 rich gas additionally contains H2O.
5 . The method according to claim 1 , wherein at least partly calcining the raw material comprises decarbonating a raw material that contains a metal carbonate, thereby releasing CO 2 rich exhaust gas, wherein said CO 2 rich exhaust gas is drawn off from the first calcination device and at least partly used for said first and/or second flow of the CO 2 rich gas.
6 . The method according to claim 1 , wherein the CO 2 rich gas of the first flow and/or of the second flow of CO 2 rich gas contains at least 80 vol.-% CO 2 .
7 . The method according to claim 1 , wherein a ratio of the a sum of the first flow and the second flow of the CO 2 rich gas to the electric power used to operate the plasma torch is adjusted to 0.25-5.0, expressed as kWh/Nm 3 .
8 . The method according to claim 1 , further comprising introducing the partly calcined raw material into a second calcination device and further calcining the material in order to obtain a cementitious material.
9 . The method according to claim 8 , wherein the first calcination device is a precalciner of a cement manufacturing plant and the second calcination device is rotary kiln of the cement manufacturing plant.
10 . The method according to claim 1 , wherein the flow of raw material is preheated before being introduced into the first calcination device.
11 . The method according to claim 10 , wherein a CO 2 rich exhaust gas is withdrawn from the first calcination device, and said CO 2 rich exhaust gas is used as said heat exchanging fluid to preheat the raw material.
12 . The method according to claim 5 , wherein the CO 2 rich exhaust gas is re-heated in a heat storage and/or generating device and introduced into the first calcination device.
13 . The method according to claim 12 , wherein the heat storage device is loaded with thermal energy by means of a heating device that is operated by electrical energy.
14 . The method according to claim 8 , wherein the cementitious material is introduced into a cooling device, in which the CO 2 rich exhaust gas is used to cool the cementitious material, while the CO 2 rich exhaust gas is re-heated and then introduced into the second calcination device.
15 . The method according to claim 8 , wherein the second calcination device is heated by electrical energy and/or by combusting a renewable fuel and/or by combusting hydrogen.
16 . The method according to claim 1 , wherein the raw material consists of or comprises natural cement raw meal components, clay, or waste materials.
17 . The method according to claim 5 , wherein the metal carbonate is CaCO 3 .
18 . The method according to claim 7 , wherein the ratio of the sum of the first flow and the second flow of the CO 2 rich gas to the electric power used to operate the plasma torch is from 1.0 to 3.0 expressed as kWh/Nm 3 .
19 . The method according to claim 8 , wherein the cementitious material is a cement clinker.
20 . The method according to claim 10 , wherein the preheating is carried out by bringing a heat exchanging fluid into a heat exchanging relationship with the raw material, while the heat exchanging fluid is cooled.