The Experts below are selected from a list of 3624 Experts worldwide ranked by ideXlab platform
Tatsuo Hirano - One of the best experts on this subject based on the ideXlab platform.
-
solvent de ashing from heavy product of brown coal liquefaction using coal derived naphtha
Fuel Processing Technology, 1999Co-Authors: Osamu Okuma, Tatsuo Hirano, Noriyuki Okuyama, Kaoru MasudaAbstract:The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. In this process, the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation, which is named CLB (coal liquid bottom), is treated in a solvent at high temperature (200–290°C) and high pressure (5 MPa) to remove the ash and heavy preasphaltenes (solvent de-ashing). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent. After dissolving the CLB into the solvent, insoluble solid particles which consist of the ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated Slurry. The de-ashing efficiency (recovery of the heavy product and rate of ash removal) depends on the operating conditions and the properties of CLB and solvent, because they affect the extract yield from CLB, the settling velocity and concentration of the ash in the settler. This paper describes the stable operating conditions of the de-ashing plant using a coal-derived naphtha produced in the primary hydrogenation by discussing the effects of such parameters on the de-ashing efficiency. The de-ashing experiments with batch and continuous systems using the naphtha were carried out to determine the extract yield from CLB (eCLB), the settling velocity of the ash boundary (VNP) and the maximum ash content (ZNP) in underflow of the settler under the de-ashing conditions. According to the results of these experiments, the equations expressing eCLB, VNP and ZNP are introduced by using the de-ashing conditions, the naphtha density and the properties of CLB expressed by analytical results of ash content and solvent extraction. The stable operating conditions of a continuous de-ashing system using coal-derived naphtha can be fixed by determining the upward velocity of solution in the settler, and the flow rates of ash in underflow and Feed Slurry based on the predictions of these equations.
-
solvent de ashing from heavy product of brown coal liquefaction using toluene 2 concentration and separation of ash with a continuous de ashing system
Fuel Processing Technology, 1998Co-Authors: Osamu Okuma, Kaoru Masuda, Noriyuki Okuyama, Tatsuo HiranoAbstract:The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. The BCL process has a solvent de-ashing step to remove the ash and heavy preasphaltenes from the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation and named CLB (coal liquid bottom). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent (DAS). After dissolving the CLB into the solvent (CLB/solvent ratio, 1/8–1/4, w/w) under high temperature (200–290°C) and high pressure (4–5 MPa), insoluble solid particles which consist of ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated Slurry. The ash-concentrated Slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashed heavy product is recovered from the solution by eliminating the solvent and is further hydrogenated in secondary hydrogenation. The authors have reported on the solubility of CLB in toluene and the settling velocity (V) of the boundary of ash content in the settler under de-ashing conditions. This paper discusses the effects of de-ashing conditions on ash concentration in the settler bottom and the operating conditions of a continuous de-ashing system. The ash content in underflow (CUF, kg/kg or wt.%) at the settler bottom was found to increase with temperature and to decrease with the rate (flux) of downward flow (underflow). The maximum CUF, Z, is expressed by the equation: Z=BCLB(FL/0.35)−0.32(T/523)4.26, where BCLB, FL and T are the characteristic parameters of organic CLB (kg/kg or wt.%), flux of underflow in the settler (kg/m2 s) and temperature (K), respectively. BCLB is also expressed by using the analytical results of organic insolubles in the CLB under de-ashing conditions. Finally, stable operating conditions of a continuous de-ashing system are confirmed to be determined as the following qualifications: |Vu| WSA/CUF and Z>CUF, where |Vu|, |V|, WSA and WUF are the upward velocity of the solution in the settler (mm/s), settling velocity of the ash boundary (mm/s) in the settler, flow rate of ash in the Feed Slurry (kg/h) and flow rate of underflow (kg/h), respectively. Under these qualified conditions, the 50 t/d pilot plant constructed in Australia was operated under stable conditions for 3700 h using toluene as a DAS.
-
solvent de ashing from heavy product of brown coal liquefaction using toluene 1 solubility of heavy products and settling velocity of ash
Fuel Processing Technology, 1997Co-Authors: Osamu Okuma, Kaoru Masuda, Noriyuki Okuyama, Tatsuo HiranoAbstract:The Brown Coal Liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. In the BCL process, the heavy product (vacuum residue) derived from the coal in the primary hydrogenation, which is named CLB (coal liquid bottom, boiling point > 420°C), is treated in a solvent (CLB/solvent ratio, 18–14, wt./wt.) under high temperature (200–290°C) and high pressure (4–5 MPa) to remove the ash and heavy preasphaltenes. This solvent de-ashing process uses toluene or coal-derived naphtha as a de-ashing solvent. After dissolving the CLB into the solvent, insoluble solid particles which consist of the ash and heavy preasphaltenes are settled in a settler by gravity and separated from the solution as an ash-concentrated Slurry. The ash-concentrated Slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashing solvent is recovered from both the overflow and underflow by distillation, and reused in the de-ashing process. The de-ashed heavy product recovered from the solution by eliminating the solvent is further hydrogenated in the secondary hydrogenation. This paper discusses the solubility of the CLB into toluene and settling velocity of the ash under the de-ashing conditions. The extraction experiments made clear that toluene dissolved ∼ 60 wt.% of preasphaltenes (benzene insoluble-pyridine solubles) in the CLB under the following conditions, temperature 100–300°C and CLB/toluene ratio (wt./wt.) of 13 or less. This solubility of CLB (ϵCLB) under the de-ashing conditions is expressed as ϵCLB = CBS + 0.6CBIorg, where CBS and CBIorg are the contents of benzene solubles and organic benzene insolubles, respectively, and organic CLB (ash-free CLB) = CBS + CBIorg. The de-ashing experiments confirmed that the insolubles including ash formed a boundary of concentration during the settling period, and the de-ashing efficiency was represented by the settling velocity of the boundary (V), V is expressed as V = ACLB(CSA/2.5)−0.91(T/573)9.5. Where, ACLB, CSAand T are parameters expressing the properties of organic CLB, ash content in the Feed Slurry (wt.%) and temperature (K), respectively. The ACLB is also expressed by using the analytical results of the organic insolubles in the CLB under the de-ashing conditions. The ash content of the de-ashed heavy product recovered from the upper zone of the boundary is less than 3000 ppm, which is low enough to Feed as a mixture with two times of the middle distillate to the secondary hydrogenation over NiMo catalyst with fixed bed reactors.
Osamu Okuma - One of the best experts on this subject based on the ideXlab platform.
-
solvent de ashing from heavy product of brown coal liquefaction using coal derived naphtha
Fuel Processing Technology, 1999Co-Authors: Osamu Okuma, Tatsuo Hirano, Noriyuki Okuyama, Kaoru MasudaAbstract:The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. In this process, the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation, which is named CLB (coal liquid bottom), is treated in a solvent at high temperature (200–290°C) and high pressure (5 MPa) to remove the ash and heavy preasphaltenes (solvent de-ashing). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent. After dissolving the CLB into the solvent, insoluble solid particles which consist of the ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated Slurry. The de-ashing efficiency (recovery of the heavy product and rate of ash removal) depends on the operating conditions and the properties of CLB and solvent, because they affect the extract yield from CLB, the settling velocity and concentration of the ash in the settler. This paper describes the stable operating conditions of the de-ashing plant using a coal-derived naphtha produced in the primary hydrogenation by discussing the effects of such parameters on the de-ashing efficiency. The de-ashing experiments with batch and continuous systems using the naphtha were carried out to determine the extract yield from CLB (eCLB), the settling velocity of the ash boundary (VNP) and the maximum ash content (ZNP) in underflow of the settler under the de-ashing conditions. According to the results of these experiments, the equations expressing eCLB, VNP and ZNP are introduced by using the de-ashing conditions, the naphtha density and the properties of CLB expressed by analytical results of ash content and solvent extraction. The stable operating conditions of a continuous de-ashing system using coal-derived naphtha can be fixed by determining the upward velocity of solution in the settler, and the flow rates of ash in underflow and Feed Slurry based on the predictions of these equations.
-
solvent de ashing from heavy product of brown coal liquefaction using toluene 2 concentration and separation of ash with a continuous de ashing system
Fuel Processing Technology, 1998Co-Authors: Osamu Okuma, Kaoru Masuda, Noriyuki Okuyama, Tatsuo HiranoAbstract:The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. The BCL process has a solvent de-ashing step to remove the ash and heavy preasphaltenes from the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation and named CLB (coal liquid bottom). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent (DAS). After dissolving the CLB into the solvent (CLB/solvent ratio, 1/8–1/4, w/w) under high temperature (200–290°C) and high pressure (4–5 MPa), insoluble solid particles which consist of ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated Slurry. The ash-concentrated Slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashed heavy product is recovered from the solution by eliminating the solvent and is further hydrogenated in secondary hydrogenation. The authors have reported on the solubility of CLB in toluene and the settling velocity (V) of the boundary of ash content in the settler under de-ashing conditions. This paper discusses the effects of de-ashing conditions on ash concentration in the settler bottom and the operating conditions of a continuous de-ashing system. The ash content in underflow (CUF, kg/kg or wt.%) at the settler bottom was found to increase with temperature and to decrease with the rate (flux) of downward flow (underflow). The maximum CUF, Z, is expressed by the equation: Z=BCLB(FL/0.35)−0.32(T/523)4.26, where BCLB, FL and T are the characteristic parameters of organic CLB (kg/kg or wt.%), flux of underflow in the settler (kg/m2 s) and temperature (K), respectively. BCLB is also expressed by using the analytical results of organic insolubles in the CLB under de-ashing conditions. Finally, stable operating conditions of a continuous de-ashing system are confirmed to be determined as the following qualifications: |Vu| WSA/CUF and Z>CUF, where |Vu|, |V|, WSA and WUF are the upward velocity of the solution in the settler (mm/s), settling velocity of the ash boundary (mm/s) in the settler, flow rate of ash in the Feed Slurry (kg/h) and flow rate of underflow (kg/h), respectively. Under these qualified conditions, the 50 t/d pilot plant constructed in Australia was operated under stable conditions for 3700 h using toluene as a DAS.
-
solvent de ashing from heavy product of brown coal liquefaction using toluene 1 solubility of heavy products and settling velocity of ash
Fuel Processing Technology, 1997Co-Authors: Osamu Okuma, Kaoru Masuda, Noriyuki Okuyama, Tatsuo HiranoAbstract:The Brown Coal Liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. In the BCL process, the heavy product (vacuum residue) derived from the coal in the primary hydrogenation, which is named CLB (coal liquid bottom, boiling point > 420°C), is treated in a solvent (CLB/solvent ratio, 18–14, wt./wt.) under high temperature (200–290°C) and high pressure (4–5 MPa) to remove the ash and heavy preasphaltenes. This solvent de-ashing process uses toluene or coal-derived naphtha as a de-ashing solvent. After dissolving the CLB into the solvent, insoluble solid particles which consist of the ash and heavy preasphaltenes are settled in a settler by gravity and separated from the solution as an ash-concentrated Slurry. The ash-concentrated Slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashing solvent is recovered from both the overflow and underflow by distillation, and reused in the de-ashing process. The de-ashed heavy product recovered from the solution by eliminating the solvent is further hydrogenated in the secondary hydrogenation. This paper discusses the solubility of the CLB into toluene and settling velocity of the ash under the de-ashing conditions. The extraction experiments made clear that toluene dissolved ∼ 60 wt.% of preasphaltenes (benzene insoluble-pyridine solubles) in the CLB under the following conditions, temperature 100–300°C and CLB/toluene ratio (wt./wt.) of 13 or less. This solubility of CLB (ϵCLB) under the de-ashing conditions is expressed as ϵCLB = CBS + 0.6CBIorg, where CBS and CBIorg are the contents of benzene solubles and organic benzene insolubles, respectively, and organic CLB (ash-free CLB) = CBS + CBIorg. The de-ashing experiments confirmed that the insolubles including ash formed a boundary of concentration during the settling period, and the de-ashing efficiency was represented by the settling velocity of the boundary (V), V is expressed as V = ACLB(CSA/2.5)−0.91(T/573)9.5. Where, ACLB, CSAand T are parameters expressing the properties of organic CLB, ash content in the Feed Slurry (wt.%) and temperature (K), respectively. The ACLB is also expressed by using the analytical results of the organic insolubles in the CLB under the de-ashing conditions. The ash content of the de-ashed heavy product recovered from the upper zone of the boundary is less than 3000 ppm, which is low enough to Feed as a mixture with two times of the middle distillate to the secondary hydrogenation over NiMo catalyst with fixed bed reactors.
Kaoru Masuda - One of the best experts on this subject based on the ideXlab platform.
-
solvent de ashing from heavy product of brown coal liquefaction using coal derived naphtha
Fuel Processing Technology, 1999Co-Authors: Osamu Okuma, Tatsuo Hirano, Noriyuki Okuyama, Kaoru MasudaAbstract:The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. In this process, the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation, which is named CLB (coal liquid bottom), is treated in a solvent at high temperature (200–290°C) and high pressure (5 MPa) to remove the ash and heavy preasphaltenes (solvent de-ashing). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent. After dissolving the CLB into the solvent, insoluble solid particles which consist of the ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated Slurry. The de-ashing efficiency (recovery of the heavy product and rate of ash removal) depends on the operating conditions and the properties of CLB and solvent, because they affect the extract yield from CLB, the settling velocity and concentration of the ash in the settler. This paper describes the stable operating conditions of the de-ashing plant using a coal-derived naphtha produced in the primary hydrogenation by discussing the effects of such parameters on the de-ashing efficiency. The de-ashing experiments with batch and continuous systems using the naphtha were carried out to determine the extract yield from CLB (eCLB), the settling velocity of the ash boundary (VNP) and the maximum ash content (ZNP) in underflow of the settler under the de-ashing conditions. According to the results of these experiments, the equations expressing eCLB, VNP and ZNP are introduced by using the de-ashing conditions, the naphtha density and the properties of CLB expressed by analytical results of ash content and solvent extraction. The stable operating conditions of a continuous de-ashing system using coal-derived naphtha can be fixed by determining the upward velocity of solution in the settler, and the flow rates of ash in underflow and Feed Slurry based on the predictions of these equations.
-
solvent de ashing from heavy product of brown coal liquefaction using toluene 2 concentration and separation of ash with a continuous de ashing system
Fuel Processing Technology, 1998Co-Authors: Osamu Okuma, Kaoru Masuda, Noriyuki Okuyama, Tatsuo HiranoAbstract:The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. The BCL process has a solvent de-ashing step to remove the ash and heavy preasphaltenes from the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation and named CLB (coal liquid bottom). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent (DAS). After dissolving the CLB into the solvent (CLB/solvent ratio, 1/8–1/4, w/w) under high temperature (200–290°C) and high pressure (4–5 MPa), insoluble solid particles which consist of ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated Slurry. The ash-concentrated Slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashed heavy product is recovered from the solution by eliminating the solvent and is further hydrogenated in secondary hydrogenation. The authors have reported on the solubility of CLB in toluene and the settling velocity (V) of the boundary of ash content in the settler under de-ashing conditions. This paper discusses the effects of de-ashing conditions on ash concentration in the settler bottom and the operating conditions of a continuous de-ashing system. The ash content in underflow (CUF, kg/kg or wt.%) at the settler bottom was found to increase with temperature and to decrease with the rate (flux) of downward flow (underflow). The maximum CUF, Z, is expressed by the equation: Z=BCLB(FL/0.35)−0.32(T/523)4.26, where BCLB, FL and T are the characteristic parameters of organic CLB (kg/kg or wt.%), flux of underflow in the settler (kg/m2 s) and temperature (K), respectively. BCLB is also expressed by using the analytical results of organic insolubles in the CLB under de-ashing conditions. Finally, stable operating conditions of a continuous de-ashing system are confirmed to be determined as the following qualifications: |Vu| WSA/CUF and Z>CUF, where |Vu|, |V|, WSA and WUF are the upward velocity of the solution in the settler (mm/s), settling velocity of the ash boundary (mm/s) in the settler, flow rate of ash in the Feed Slurry (kg/h) and flow rate of underflow (kg/h), respectively. Under these qualified conditions, the 50 t/d pilot plant constructed in Australia was operated under stable conditions for 3700 h using toluene as a DAS.
-
solvent de ashing from heavy product of brown coal liquefaction using toluene 1 solubility of heavy products and settling velocity of ash
Fuel Processing Technology, 1997Co-Authors: Osamu Okuma, Kaoru Masuda, Noriyuki Okuyama, Tatsuo HiranoAbstract:The Brown Coal Liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. In the BCL process, the heavy product (vacuum residue) derived from the coal in the primary hydrogenation, which is named CLB (coal liquid bottom, boiling point > 420°C), is treated in a solvent (CLB/solvent ratio, 18–14, wt./wt.) under high temperature (200–290°C) and high pressure (4–5 MPa) to remove the ash and heavy preasphaltenes. This solvent de-ashing process uses toluene or coal-derived naphtha as a de-ashing solvent. After dissolving the CLB into the solvent, insoluble solid particles which consist of the ash and heavy preasphaltenes are settled in a settler by gravity and separated from the solution as an ash-concentrated Slurry. The ash-concentrated Slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashing solvent is recovered from both the overflow and underflow by distillation, and reused in the de-ashing process. The de-ashed heavy product recovered from the solution by eliminating the solvent is further hydrogenated in the secondary hydrogenation. This paper discusses the solubility of the CLB into toluene and settling velocity of the ash under the de-ashing conditions. The extraction experiments made clear that toluene dissolved ∼ 60 wt.% of preasphaltenes (benzene insoluble-pyridine solubles) in the CLB under the following conditions, temperature 100–300°C and CLB/toluene ratio (wt./wt.) of 13 or less. This solubility of CLB (ϵCLB) under the de-ashing conditions is expressed as ϵCLB = CBS + 0.6CBIorg, where CBS and CBIorg are the contents of benzene solubles and organic benzene insolubles, respectively, and organic CLB (ash-free CLB) = CBS + CBIorg. The de-ashing experiments confirmed that the insolubles including ash formed a boundary of concentration during the settling period, and the de-ashing efficiency was represented by the settling velocity of the boundary (V), V is expressed as V = ACLB(CSA/2.5)−0.91(T/573)9.5. Where, ACLB, CSAand T are parameters expressing the properties of organic CLB, ash content in the Feed Slurry (wt.%) and temperature (K), respectively. The ACLB is also expressed by using the analytical results of the organic insolubles in the CLB under the de-ashing conditions. The ash content of the de-ashed heavy product recovered from the upper zone of the boundary is less than 3000 ppm, which is low enough to Feed as a mixture with two times of the middle distillate to the secondary hydrogenation over NiMo catalyst with fixed bed reactors.
Noriyuki Okuyama - One of the best experts on this subject based on the ideXlab platform.
-
solvent de ashing from heavy product of brown coal liquefaction using coal derived naphtha
Fuel Processing Technology, 1999Co-Authors: Osamu Okuma, Tatsuo Hirano, Noriyuki Okuyama, Kaoru MasudaAbstract:The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. In this process, the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation, which is named CLB (coal liquid bottom), is treated in a solvent at high temperature (200–290°C) and high pressure (5 MPa) to remove the ash and heavy preasphaltenes (solvent de-ashing). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent. After dissolving the CLB into the solvent, insoluble solid particles which consist of the ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated Slurry. The de-ashing efficiency (recovery of the heavy product and rate of ash removal) depends on the operating conditions and the properties of CLB and solvent, because they affect the extract yield from CLB, the settling velocity and concentration of the ash in the settler. This paper describes the stable operating conditions of the de-ashing plant using a coal-derived naphtha produced in the primary hydrogenation by discussing the effects of such parameters on the de-ashing efficiency. The de-ashing experiments with batch and continuous systems using the naphtha were carried out to determine the extract yield from CLB (eCLB), the settling velocity of the ash boundary (VNP) and the maximum ash content (ZNP) in underflow of the settler under the de-ashing conditions. According to the results of these experiments, the equations expressing eCLB, VNP and ZNP are introduced by using the de-ashing conditions, the naphtha density and the properties of CLB expressed by analytical results of ash content and solvent extraction. The stable operating conditions of a continuous de-ashing system using coal-derived naphtha can be fixed by determining the upward velocity of solution in the settler, and the flow rates of ash in underflow and Feed Slurry based on the predictions of these equations.
-
solvent de ashing from heavy product of brown coal liquefaction using toluene 2 concentration and separation of ash with a continuous de ashing system
Fuel Processing Technology, 1998Co-Authors: Osamu Okuma, Kaoru Masuda, Noriyuki Okuyama, Tatsuo HiranoAbstract:The brown coal liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. The BCL process has a solvent de-ashing step to remove the ash and heavy preasphaltenes from the heavy liquefaction product (vacuum residue) derived from the coal in primary hydrogenation and named CLB (coal liquid bottom). This solvent de-ashing step uses toluene or coal-derived naphtha as a de-ashing solvent (DAS). After dissolving the CLB into the solvent (CLB/solvent ratio, 1/8–1/4, w/w) under high temperature (200–290°C) and high pressure (4–5 MPa), insoluble solid particles which consist of ash and heavy preasphaltenes are settled by gravity and separated from the solution as an ash-concentrated Slurry. The ash-concentrated Slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashed heavy product is recovered from the solution by eliminating the solvent and is further hydrogenated in secondary hydrogenation. The authors have reported on the solubility of CLB in toluene and the settling velocity (V) of the boundary of ash content in the settler under de-ashing conditions. This paper discusses the effects of de-ashing conditions on ash concentration in the settler bottom and the operating conditions of a continuous de-ashing system. The ash content in underflow (CUF, kg/kg or wt.%) at the settler bottom was found to increase with temperature and to decrease with the rate (flux) of downward flow (underflow). The maximum CUF, Z, is expressed by the equation: Z=BCLB(FL/0.35)−0.32(T/523)4.26, where BCLB, FL and T are the characteristic parameters of organic CLB (kg/kg or wt.%), flux of underflow in the settler (kg/m2 s) and temperature (K), respectively. BCLB is also expressed by using the analytical results of organic insolubles in the CLB under de-ashing conditions. Finally, stable operating conditions of a continuous de-ashing system are confirmed to be determined as the following qualifications: |Vu| WSA/CUF and Z>CUF, where |Vu|, |V|, WSA and WUF are the upward velocity of the solution in the settler (mm/s), settling velocity of the ash boundary (mm/s) in the settler, flow rate of ash in the Feed Slurry (kg/h) and flow rate of underflow (kg/h), respectively. Under these qualified conditions, the 50 t/d pilot plant constructed in Australia was operated under stable conditions for 3700 h using toluene as a DAS.
-
solvent de ashing from heavy product of brown coal liquefaction using toluene 1 solubility of heavy products and settling velocity of ash
Fuel Processing Technology, 1997Co-Authors: Osamu Okuma, Kaoru Masuda, Noriyuki Okuyama, Tatsuo HiranoAbstract:The Brown Coal Liquefaction (BCL) process is a two-stage liquefaction (hydrogenation) process developed for Victorian brown coal in Australia. In the BCL process, the heavy product (vacuum residue) derived from the coal in the primary hydrogenation, which is named CLB (coal liquid bottom, boiling point > 420°C), is treated in a solvent (CLB/solvent ratio, 18–14, wt./wt.) under high temperature (200–290°C) and high pressure (4–5 MPa) to remove the ash and heavy preasphaltenes. This solvent de-ashing process uses toluene or coal-derived naphtha as a de-ashing solvent. After dissolving the CLB into the solvent, insoluble solid particles which consist of the ash and heavy preasphaltenes are settled in a settler by gravity and separated from the solution as an ash-concentrated Slurry. The ash-concentrated Slurry and the de-ashed solution are withdrawn from the settler as an underflow and overflow, respectively. The de-ashing solvent is recovered from both the overflow and underflow by distillation, and reused in the de-ashing process. The de-ashed heavy product recovered from the solution by eliminating the solvent is further hydrogenated in the secondary hydrogenation. This paper discusses the solubility of the CLB into toluene and settling velocity of the ash under the de-ashing conditions. The extraction experiments made clear that toluene dissolved ∼ 60 wt.% of preasphaltenes (benzene insoluble-pyridine solubles) in the CLB under the following conditions, temperature 100–300°C and CLB/toluene ratio (wt./wt.) of 13 or less. This solubility of CLB (ϵCLB) under the de-ashing conditions is expressed as ϵCLB = CBS + 0.6CBIorg, where CBS and CBIorg are the contents of benzene solubles and organic benzene insolubles, respectively, and organic CLB (ash-free CLB) = CBS + CBIorg. The de-ashing experiments confirmed that the insolubles including ash formed a boundary of concentration during the settling period, and the de-ashing efficiency was represented by the settling velocity of the boundary (V), V is expressed as V = ACLB(CSA/2.5)−0.91(T/573)9.5. Where, ACLB, CSAand T are parameters expressing the properties of organic CLB, ash content in the Feed Slurry (wt.%) and temperature (K), respectively. The ACLB is also expressed by using the analytical results of the organic insolubles in the CLB under the de-ashing conditions. The ash content of the de-ashed heavy product recovered from the upper zone of the boundary is less than 3000 ppm, which is low enough to Feed as a mixture with two times of the middle distillate to the secondary hydrogenation over NiMo catalyst with fixed bed reactors.
Pavel R Hrma - One of the best experts on this subject based on the ideXlab platform.
-
cold cap formation from a Slurry Feed during nuclear waste vitrification
Ceramics International, 2019Co-Authors: Miroslava Hujova, Pavel R Hrma, Jaroslav Klouzek, Derek A Cutforth, Seungmin Lee, Benjamin P Mccarthy, Albert A Kruger, Micah D Miller, Richard PokornyAbstract:Abstract The time-temperature history of waste Slurry Feed during melting strongly affects various kinetic processes, such as reaction or dissolution rates, and, consequently, the melting rate. To analyze the time-temperature history of the Feed in a cold-cap during nuclear waste vitrification, this work focuses on understanding how the main cold-cap body forms, how the aqueous Feed Slurry interacts with the cold-cap, and estimating the cold-cap heat conductivity. To simulate the conditions during cold-cap formation, samples were prepared by rapid water evaporation from Slurry Feed. After water evaporated from the sample, a fresh Slurry with tracer was poured onto the dry sample. X-ray fluorescence was then used to investigate the degree of penetration and/or mixing between the incoming Slurry and the original sample. We show that the Slurry does not interact or mix with the previously dry cold-cap crust, but that water-soluble components concentrate at the bottom of the boiling pools, where most of the water evaporates. Further, using the rate of water evaporation, the heat conductivity of the cold-cap was calculated from the measured temperature profile. The resulting conductivity is significantly higher than the values obtained in previous studies. We discuss the implications of the results for the cold-cap formation in the melter and for the development of the cold-cap mathematical model.
-
determination of heat conductivity of waste glass Feed and its applicability for modeling the batch to glass conversion
Journal of the American Ceramic Society, 2017Co-Authors: Miroslava Hujova, Richard Pokorny, Jaroslav Klouzek, Derek R Dixon, Derek A Cutforth, Seungmin Lee, Benjamin P Mccarthy, Michael J Schweiger, Albert A Kruger, Pavel R HrmaAbstract:The effective heat conductivity (λ) of reacting melter Feed affects the heat transfer and conversion process in the cold cap, the reacting Feed floating on molten glass. A heat conductivity meter was used to measure λ of samples of a cold cap retrieved from a laboratory-scale melter, loose dry powder Feed samples, and samples cut from fast-dried Slurry blocks. These blocks were formed to simulate the Feed conditions in the cold-cap by rapidly evaporating water from Feed Slurry poured onto a 200°C surface. Our study indicates that the effective heat conductivity of the Feed in the cold cap is significantly higher than that of loose dry powder Feed, which is a result of the Feed solidification during the water evaporation from the Feed Slurry. To assess the heat transfer at higher temperatures when Feed turns into foam, we developed a theoretical model that predicts the foam heat conductivity based on morphology data from in-situ X-ray computed tomography. The implications for the mathematical modeling of the cold cap are discussed. This article is protected by copyright. All rights reserved.
-
conversion of nuclear waste into nuclear waste glass experimental investigation and mathematical modeling
Procedia Materials Science, 2014Co-Authors: Pavel R HrmaAbstract:Abstract The melter Feed, Slurry, or calcine charged on the top of a pool of molten glass forms a floating layer of reacting material called the cold cap. Between the cold-cap top, which is covered with boiling Slurry, and its bottom, where bubbles separate it from molten glass, the temperature changes by up to 1000 K. The processes that occur over this temperature interval within the cold cap include liberation of gases, conduction and consumption of heat, dissolution of quartz particles, formation and dissolution of intermediate crystalline phases, and generation of foam and gas cavities. These processes have been investigated using thermal analyses, optical and electronic microscopies, x-ray diffraction, as well as other techniques. Properties of the reacting Feed, such as heat conductivity and density, were measured as functions of temperature. Investigating the structure of quenched cold caps produced in a laboratory-scale melter complemented the crucible studies. The cold cap consists of two main layers. The top layer contains solid particles dissolving in the glass-forming melt and open pores through which gases are escaping. The bottom layer contains bubbly melt or foam where bubbles coalesce into larger cavities that move sideways and release the gas to the atmosphere. The Feed-to-glass conversion became sufficiently understood for representing the cold-cap processes via mathematical models. These models, which comprise heat transfer, mass transfer, and reaction kinetics models, have been developed with the final goal to relate Feed parameters to the rate of glass melting.