WO2018091069A1 - Process and plant for the treatment of carbonaceous slurry - Google Patents
Process and plant for the treatment of carbonaceous slurry Download PDFInfo
- Publication number
- WO2018091069A1 WO2018091069A1 PCT/EP2016/077687 EP2016077687W WO2018091069A1 WO 2018091069 A1 WO2018091069 A1 WO 2018091069A1 EP 2016077687 W EP2016077687 W EP 2016077687W WO 2018091069 A1 WO2018091069 A1 WO 2018091069A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- gas
- vapor
- mixture
- water
- oxygen
- Prior art date
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F11/00—Treatment of sludge; Devices therefor
- C02F11/06—Treatment of sludge; Devices therefor by oxidation
- C02F11/08—Wet air oxidation
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2103/00—Nature of the water, waste water, sewage or sludge to be treated
- C02F2103/16—Nature of the water, waste water, sewage or sludge to be treated from metallurgical processes, i.e. from the production, refining or treatment of metals, e.g. galvanic wastes
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/02—Temperature
-
- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F2209/00—Controlling or monitoring parameters in water treatment
- C02F2209/03—Pressure
Definitions
- the present invention relates to a process and a plant for the treatment of car- bonaceous slurry in general, produced by an upstream alumina production process in particular, comprising the steps of injecting a gas containing oxygen into said slurry at temperatures of 150 °C to 350 °C and pressures above the associated boiling points resulting in a vapor-/gas- mixture, mainly comprising water, oxygen, nitrogen and hydrogen, determining the volume fraction of water vapor in said vapor-/gas- mixture and stopping the injection of gas comprising oxygen, preferably oxygen enriched gas or pure oxygen, in case the volume fraction of water vapor is below 0.84 in said vapor-/gas- mixture.
- carbonaceous molecules are flamelessly combusted (i.e. oxidized) at elevated temperature and pressures by an oxidant, e.g. oxygen, contained in as air or as pure oxygen, which is commonly referred to as wet oxidation and is described in US 2,665,249.
- an oxidant e.g. oxygen
- oxygen contained in as air or as pure oxygen
- wet oxidation which is commonly referred to as wet oxidation and is described in US 2,665,249.
- the oxygen is no longer in the gas phase when acting as an oxidant. It dissolves into the liquid first and the oxidized.
- the oxygen is supplied in substoichiometric and below solubility. The aim is to avoid excess O 2 in the off-gas to be oxidized matter.
- wet oxidation is a rather energy and cost efficient process to produce a basically clean liquor phase.
- Modern understanding of the wet oxidation process chemistry is that the bi- radical oxygen starts a radical reaction by reaction with water and/or the carbonaceous molecules.
- a common problem of wet oxidation is the increased generation of hydrogen as a by-product via recombination of a hydrogen atom and water molecules forming elemental hydrogen- and OH-radicals. Even in the produced small amounts of hydrogen may form an explosive mixture with any oxygen that may be present in the gas phase, wherein the mixture is easily ignited at the elevated temperatures and pressures required for the wet oxidation process.
- Arnswald Removal of organic carbon from Bayer liquor by wet oxidation in tube digesters", Light Metals 1991 , pages 23 to 27
- a gas mixture containing the species water vapor, hydrogen and oxygen is not explosive, as long as the water vapor content in a mixture of water vapor, hydrogen and oxygen exceeds a volume fraction of 0.84.
- a dead time between the extraction of the to be analyzed gas and the detection of an explosive hydrogen/ oxygen mixture of up to 90 seconds is to be expected, since the vapor-/gas- mixture is to be extracted and refined before the oxygen content is analyzed by analyzers downstream of the process.
- the present invention provides a process for the treatment of carbonaceous slurry, as for instance produced by an upstream alumina production process.
- a gas comprising oxygen preferably an oxygen rich gas with an oxygen content of > 20 vol.-%
- a vapor-/gas- mixture at least comprising water, and hydrogen is obtained. This is due to the decomposition of the carbonaceous molecules resulting in the formation of water and hydrogen via a side reaction.
- the prior art utilizes oxygen sensors for determination of the oxygen content in the vapor-/gas- mixture
- the present invention proposes the determination of the volume fraction of water in said vapor-/gas- mixture.
- the volume fraction of water is below 0.84. preferably 0,9
- the injection of gas comprising oxygen is immediately stopped, which prevents further formation of an explosive oxygen/ hydrogen mixture.
- the molar fraction of water in the vapor-/gas- mixture is determined as follows:
- the pressure of the mixture of water vapor and non-condensables (NC) such as hydrogen and oxygen measured at any process point of the process represents the absolute pressure of that mixture, consisting of the sum of the partial pressures of water vapor and non-condensables. Measuring the absolute pressure and the temperature at a given process point allows to determine the following:
- the temperature measured at a given process point is the temperature corresponding to the partial pressure of the saturated steam in the water vapor/non- condensable mixture at that process point.
- the corresponding saturation pressure Ps can be calculated.
- the volume fraction of a compound is defined as the amount of said compound in a given volume divided by the total amount of all constituents in the corresponding mixture.
- Figure 1 shows the respective detection of an explosive vapor-/gas-mixture by temperature-/pressure-measurement.
- the water content in the upstream process steps will be above the critical limit of 0.84, preferably 0.9, for the vol- ume fraction of water in the vapor-/gas- mixture.
- the water con- tent in the vapor-/gas- mixture deviates from the water content in the upstream process steps, in which wet oxidation occurs. Therefore, the continuous and instant determination of the volume fraction of water in the vapor-/gas- mixture allows a reduction of the dead time between formation and detection of an ex- plosive oxygen/ hydrogen mixture.
- the temperature and pressure of the vapor-/gas- mixture are used to determine the volume fraction of water at the particular point of measurement. Said determination is based on the fact, that in each point of the wet oxidation process a water saturated gas phase is obtained. In other words a dynamic equilibrium between condensed (liquid) water and water vapor is observed. For a pure (100 vol.-% water) phase this equilibrium is described by the water vapor pressure saturation- curve.
- the water saturated gas phase in a wet oxidation process also contains non-condensable gases such as hydrogen and oxygen.
- the equilibrium between condensed and vaporous water is "distorted", such that the temperature of a saturated water mixture is no longer correlated to the absolute pressure, but to the partial pressure of the water, which then allows to quantify volume fraction or molar fraction of water.
- the presence of the non- condensable gases results in a temperature measured, which is lower than if compared to the temperature to be expected for a pure water phase.
- temperature and pressure sensors are used in accordance with the invention. Since these sensors are required for the control of the wet oxidation process parameters, no additional sensors may be necessary. Further, tempera- ture and pressure sensors are very robust and require little maintenance, the overall process costs are reduced.
- the molar fraction of water is 0.84 to 1 .0, preferably 0.9 to 1 .0
- the molar fraction of oxygen is 0 to 0.16
- the molar fraction of hydrogen is 0 to 0.16 and wherein the sum of the molar fractions of all constituents of the vapor- /gas- mixture is 1 .
- the molar fraction of water is determined by the procedure described above.
- Figure 2 shows temperature differences measured at a given system pressure with water vapor fraction of 0,84 in the water-vapor mixture.
- the temperature and the pressure of the vapor-/gas- mixture is measured after separation of a major part of water, e.g. via condensation in a condenser vapor-/gas- mixture.
- the con- densation of water may be stopped same as the introduction of oxygen containing gas in cases the determined water vapor fraction is too low.
- the stopped condensation increases the water content downstream of the condenser and thus further prevents the formation of an explosive hydrogen / oxygen mixture downstream of the condenser.
- a chemically inert gas e.g. nitrogen
- a chemically inert gas is added to the vapor-/gas- mixture removed from the at least one flash tank. This may be done directly after the flash tank. However, it is particularly preferred to provide an inlet downstream of the separation of water, since a formation of an explo- sive mixture is promoted by water separation.
- the addition of a chemically inert gas further provides a procedure, which very rapidly, i.e. within less than 30 seconds, can adjust the hydrogen/ oxygen mixture to non-explosive conditions.
- the amount of inert gas such as nitrogen is adjusted such that in case in the vapor-/gas- mixture in case a molar fraction of water of less than 0.84 is determined. This further prevents the existence of an explosive hydrogen/ oxygen mixture is prevented.
- the object of the present invention is further solved by a plant for the treatment of carbonaceous slurry according to the features of plant claim 7.
- such a plant in particular downstream of an alumina production process, comprises at least one flash tank with at least one inlet for introduction of -with respect to its content on carbonaceous matter- untreated and/or partial- ly treated slurry provided via a supply tube.
- a gas supply tube is provided for introduction of a gas comprising oxygen to said slurry upstream of the flash tank to allow for the necessary residence time for the dissolution of the oxygen into said slurry and its reaction with the carbonaceous matter.
- the gas supply tube comprises a valve for regulation of the oxygen amount introduced into the process.
- the flash tank has a gas-/vapor- outlet tube for discharging the vapor-/gas-mixture from at least one flash tank.
- the plant also comprises at least one temperature sensor for measuring the temperature of said vapor-/gas- mixture, and one pressure sensor for measuring the pressure of said vapor- /gas- mixture, and a control and computation unit for determining the volume fraction of water.
- the valve of the gas supply tube is closed in case the molar fraction of water vapor is below 0.84 in the vapor-/gas- mixture in order to avoid the formation of an explosive mixture.
- the plant comprises at least one condenser vapor- /gas- mixture.
- One or more condenser(s) connected in series or parallel may be provided downstream of the last flash tank in order to remove water from the combined vapor-/gas- mixture streams of each flash tank.
- Such a plant layout reduces the overall construction costs, since only one or few condenser(s) are required.
- one condenser has to be provided for each flash tank. Thereby, the construction costs for the corresponding plant are higher, but the conditions (like temperature and pressure) of the wet oxidation process for each flash tank can be regulated independently.
- the temperature sensor and the pres- sure sensor is (are) located downstream to the condenser.
- the gas supply tube emerges with the slurry supply tube such, that the gas comprising oxygen is introduced into the slurry upstream of the flash tank. Consequently, the reaction time between the oxygen and the carbonaceous is granted to be completed before entering the flash tank without an increase of the retention time of the slurry inside the flash tanks. In other words, a sort of pretreatment of the slurry before being introduced into the flash tank is achieved.
- the gas outlet tube in particular directly, guides the vapor-/gas- mixture to a condenser in which water is separated from the vapor-/gas- mixture.
- Fig. 1 shows a detection scheme for explosive vapor-/gas-mixtures
- Fig. 2 shows a ratio between pressure and temperature in a system according to the invention
- Fig. 3 shows schematically a plant for the treatment of carbonaceous slurry according to the present invention
- carbonaceous slurry is introduced via supply tube 1 and conduit 2 into a flash tank 10. Inside the flash tank 10, the slurry is distributed via spraying unit 1 1 such that gas / liquid or slurry separation is enhanced.
- a gas containing oxygen or technically pure oxygen (> 95 vol.-%) is introduced into the plant and flash tank 10 via gas supply tube 3 and conduit 2.
- the amount of oxygen added is regulated by regulation valve 4.
- Said valve 4 is controlled by control unit 5.
- the oxygen is directly introduced into the slurry and upstream of the flash tank 10, which increases the reaction time between oxygen and the carbonaceous materials without increasing of the retention time of the slurry in the flash tank 10.
- the generated vapor-/gas- mixture is removed and either subsequently combined with the vapor-/gas- mixture from flash tank 10 in conduit 20, or, a separate vapor-/gas- mixture removal conduit for each flash tank is provided, which increases the flexibility of the process, since each flash tank may be controlled completely independently.
- the vapor-/gas- mixture from all flash tanks are guided into at least one condenser 30, preferably however into separate and designated condensers as shown in Fig. 3.
- each flash tank may be guided into the subsequent flash tank (as shown in Fig. 3) or each removal conduit for the remaining slurry may be combined into one discharge conduit for discharging the remaining slurry.
- condenser 30 it is preferred to provide a condenser for each flash tank of the inventive plant.
- water from the vapor-/gas- mixture is condensed and thus separated from non-condensable substances.
- the non-condensable substances are mainly hydrogen and oxygen, but may also include nitrogen, carbon dioxide, carbon monoxide, methane or other by-products exhibiting a very low boiling point, e.g. below - 50 °C.
- a condensate comprising water as main constituent is removed via conduit 33.
- the water removed from condenser 30 of the inventive plant is basically free of any contamination, in particular carbonaceous material, and may be used in an upstream process, as for instance as suspension medium in an upstream Bayer-process for producing aluminum. Consequently, the inventive plant may be included in a joint system thus reducing the amount of fresh water required.
- the water may be discharged into the environment as basically pure water, in particular after further after treatment, e.g. removal of inorganic substances.
- the remaining vapor /gas mixture from the last flash tank is subjected to condensers 30 to 30x (or to the condenser assigned to each respective flash tank).
- the remaining slurry is basically free of carbonaceous matter.
- the carbonaceous matter is reduced by typically 50 to 90 % depending on process temperature, residence time and oxygen addition.
- the treated remaining slurry is removed via conduit 32 from the process.
- valves 35 to 35x and control units 36 to 36x assigned to valves 35 to 35x the amount of condensate removed from the process is regulated.
- the non-condensable constituents of the vapor-/gas- mixture are removed from the condensers 30 to 30x via conduits 37 to 37x.
- a temperature sensors 40 to 40x and a pressure sensors 41 to 41 x determine the temperature and pressure of the non-condensable constituents left after removal of the major part of water in condensers 30 to 30x. Due to the removal of water inside condensers 30 to 30x, the most critical (i.e. least) volume fraction of water is present together with hydrogen and oxygen in conduits 37 to 37x.
- the oxygen supply via conduits 3 and 2 is stopped by closing valve 4 and the formation of an explosive mixture upstream of the condenser is prevented in the first place. Further, the condensation of water in the condensers 30 to 30x may be stopped in case of an explosive mixture of hydrogen and oxygen is about to be formed downstream of the condenser.
- Example 1 The invention and the reduction of the dead time is further illustrated by means of a following example: Example 1
Abstract
Description
Claims
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
UAU201905606U UA139450U (en) | 2016-11-15 | 2016-11-15 | Process and plant for the treatment of carbonaceous slurry |
BR112019009727-9A BR112019009727B1 (en) | 2016-11-15 | 2016-11-15 | Process and plant for the treatment of carbonaceous sludge |
DE212016000295.3U DE212016000295U1 (en) | 2016-11-15 | 2016-11-15 | Plant for the treatment of a carbonaceous slurry |
PCT/EP2016/077687 WO2018091069A1 (en) | 2016-11-15 | 2016-11-15 | Process and plant for the treatment of carbonaceous slurry |
BR212019009727U BR212019009727U2 (en) | 2016-11-15 | 2016-11-15 | process and plant for the treatment of carbonaceous mud |
AU2016430162A AU2016430162B2 (en) | 2016-11-15 | 2016-11-15 | Process and plant for the treatment of carbonaceous slurry |
TR2019/07180U TR201907180U5 (en) | 2016-11-15 | 2016-11-15 | A process and apparatus for processing carbonaceous slurry. |
CN201690001838.5U CN210367384U (en) | 2016-11-15 | 2016-11-15 | Apparatus for treating carbonaceous slurry |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/EP2016/077687 WO2018091069A1 (en) | 2016-11-15 | 2016-11-15 | Process and plant for the treatment of carbonaceous slurry |
Publications (1)
Publication Number | Publication Date |
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WO2018091069A1 true WO2018091069A1 (en) | 2018-05-24 |
Family
ID=57391952
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/EP2016/077687 WO2018091069A1 (en) | 2016-11-15 | 2016-11-15 | Process and plant for the treatment of carbonaceous slurry |
Country Status (7)
Country | Link |
---|---|
CN (1) | CN210367384U (en) |
AU (1) | AU2016430162B2 (en) |
BR (2) | BR212019009727U2 (en) |
DE (1) | DE212016000295U1 (en) |
TR (1) | TR201907180U5 (en) |
UA (1) | UA139450U (en) |
WO (1) | WO2018091069A1 (en) |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2665249A (en) | 1950-03-27 | 1954-01-05 | Sterling Drug Inc | Waste disposal |
GB1537695A (en) * | 1975-06-04 | 1979-01-04 | Sterling Drug Inc | Process and apparatus for energy recovery from wet oxidation |
US4744908A (en) * | 1987-02-24 | 1988-05-17 | Vertech Treatment Systems, Inc. | Process for effecting chemical reactions |
US6423236B1 (en) * | 1999-01-07 | 2002-07-23 | Nippon Shokubai Co., Ltd. | Method for treating waste water |
EP1289893A1 (en) * | 2000-06-14 | 2003-03-12 | Voest-Alpine Industrieanlagenbau GmbH & Co. | Device and method for treating a refuse material containing hydrocarbons |
JP2008207136A (en) * | 2007-02-27 | 2008-09-11 | National Univ Corp Shizuoka Univ | Hydrothermal oxidative decomposition treatment apparatus and fertilizer manufacturing method |
-
2016
- 2016-11-15 WO PCT/EP2016/077687 patent/WO2018091069A1/en active Application Filing
- 2016-11-15 BR BR212019009727U patent/BR212019009727U2/en active IP Right Grant
- 2016-11-15 CN CN201690001838.5U patent/CN210367384U/en active Active
- 2016-11-15 BR BR112019009727-9A patent/BR112019009727B1/en active IP Right Grant
- 2016-11-15 TR TR2019/07180U patent/TR201907180U5/en unknown
- 2016-11-15 AU AU2016430162A patent/AU2016430162B2/en active Active
- 2016-11-15 UA UAU201905606U patent/UA139450U/en unknown
- 2016-11-15 DE DE212016000295.3U patent/DE212016000295U1/en active Active
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2665249A (en) | 1950-03-27 | 1954-01-05 | Sterling Drug Inc | Waste disposal |
GB1537695A (en) * | 1975-06-04 | 1979-01-04 | Sterling Drug Inc | Process and apparatus for energy recovery from wet oxidation |
US4744908A (en) * | 1987-02-24 | 1988-05-17 | Vertech Treatment Systems, Inc. | Process for effecting chemical reactions |
US6423236B1 (en) * | 1999-01-07 | 2002-07-23 | Nippon Shokubai Co., Ltd. | Method for treating waste water |
EP1289893A1 (en) * | 2000-06-14 | 2003-03-12 | Voest-Alpine Industrieanlagenbau GmbH & Co. | Device and method for treating a refuse material containing hydrocarbons |
JP2008207136A (en) * | 2007-02-27 | 2008-09-11 | National Univ Corp Shizuoka Univ | Hydrothermal oxidative decomposition treatment apparatus and fertilizer manufacturing method |
Non-Patent Citations (2)
Title |
---|
ARNSWALD: "Removal of organic carbon from Bayer liquor by wet oxidation in tube digesters", LIGHT METALS, 1991, pages 23 - 27 |
ARNSWALD: "Removal of organic carbon from Bayer liquor by wet oxidation in tube digesters", LIGHT METALS, 1991, pages 23 - 27, XP000366101 * |
Also Published As
Publication number | Publication date |
---|---|
UA139450U (en) | 2020-01-10 |
BR112019009727B1 (en) | 2022-03-29 |
TR201907180U5 (en) | 2019-06-21 |
AU2016430162B2 (en) | 2020-10-01 |
AU2016430162A1 (en) | 2019-06-06 |
CN210367384U (en) | 2020-04-21 |
BR112019009727A2 (en) | 2019-10-01 |
BR212019009727U2 (en) | 2019-10-01 |
DE212016000295U1 (en) | 2019-06-18 |
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