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
  • C02F11/083—Wet air oxidation using deep well reactors
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/72—Treatment of water, waste water, or sewage by oxidation
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/02—Treatment of water, waste water, or sewage by heating
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/72—Treatment of water, waste water, or sewage by oxidation
  • C02F1/727—Treatment of water, waste water, or sewage by oxidation using pure oxygen or oxygen rich gas
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2301/00—General aspects of water treatment
  • C02F2301/06—Pressure conditions
  • C02F2301/066—Overpressure, high pressure

Definitions

• the present invention relates to an apparatus for performing deep well wet oxidation treatment of waste and other combustible materials in an aqueous stream such as organic solvents, municipal sludge, toxic or contaminated products and the like.
• aqueous stream such as organic solvents, municipal sludge, toxic or contaminated products and the like.
• Various wet oxidation treatment processes are disclosed in the prior art.
• the temperature of combustible material dissolved and/or suspended in water in the presence of oxygen is increased to produce a wet oxidation reaction wherein complex organic materials are converted into water, carbon dioxide, dilute organic acids and a small amount of sterile, inert ash.
• the combustion reaction is exothermic and can be carried out in a reaction apparatus having a continuous heat exchanger such that the heat evolved by the combustion reaction can be used to heat an influent waste stream to the desired temperature.
• the prior art has also proposed utilizing wet oxidation processes of this type in a continuous vertical heat exchange column which may be supported in a subterranean well (i.e. deep well* 1 ) .
• the chemical reaction occurs within a vertical reaction vessel that generally extends downwardly into the ground to a depth of from 600 - 2000 m, usually 1200 m.
• the fluid to be treated is pumped into an influent tube or pipe, i.e. the Mown comer*' with other reactants for the chemical reaction.
• a fluid head creates pressure and heat is added which facilitates the reaction.
• the temperature and pressure are greatest in the lower regions of the pipe where the reaction occurs.
• the fluid continues its continuous flow upwardly through an annulus, i.e. the up co er' , where the effluent may be processed further.
• wet oxidation of the fluid waste stream occurs in the aqueous phase when sufficient oxygen, heat and pressure are present in the system.
• the wet oxidation reaction is an exothermic reaction which is capable of autogenic operation after the lower portion or reaction zone of the vertical pipes are preheated to the appropriate temperature for oxidation of the waste stream.
• the efficiency of this system is also seen in the fact that the pumps injecting the fluid waste stream theoretically only need to be large enough to overcome the wall friction and any differential head between the influent and effluent pipes.
• the vertical pipes are designed to provide sufficient residence time of the fluid waste stream in the reaction zone to complete the oxidation reactions.
• Scale build-up on the walls of the vertical tubes also reduces the efficiency of the counterflow heat exchange between the influent and the effluent through the walls of the pipes separating the two flows.
• scale accumulations on the wall of the pipe adjacent the heat exchange medium reduces the efficiency of preheating the reaction zone.
• the present invention provides an apparatus for performing a deep well wet oxidation treatment of a fluid waste stream, the apparatus at least comprising:
• first pipe for feeding the fluid waste stream into the reaction vessel, the first pipe being suspended in said reaction vessel and thereby defining a down going flow through the first pipe and an up going flow through a passage defined by the first pipe and the reaction vessel;
• the deep well reaction vessel will have a depth between 600 - 2000 m below ground surface, more usually a depth of about 1200 m.
• the fluid waste stream may be any fluid (usually aqueous) waste stream containing organic compounds, municipal sludge, etc.
• the oxidant may be any oxidant suitable for performing a wet oxidation.
• the oxidant will be an oxygen containing fluid such as air, in particular oxygen rich gas, more preferably substantially pure oxygen gas.
• oxygen containing fluid such as air, in particular oxygen rich gas, more preferably substantially pure oxygen gas.
• reaction zone the exact position of the reaction zone may vary with the circumstances, the position of the feeding of the oxidant to the reaction zone may also vary.
• the oxidant will be fed just upstream of the reaction zone, thereby avoiding that the oxidant already reacts with the fluid waste stream under pressure and temperature conditions that are not suitable for efficient wet oxidation.
• the selected temperature and pressure may depend on the fluid waste stream to be treated in order to obtain an objected COD (Chemical Oxygen Demand) reduction of the fluid waste stream.
• COD Chemical Oxygen Demand
• the layout of the reaction vessel and the heat transfer ratios define the depth at which the oxidant will be injected and the total depth of the reaction vessel.
• the suitable conditions of temperature and pressure are created in the reaction vessel to define a reaction zone wherein wet oxidation can take place.
• a fluid waste stream is fed into the first pipe (the Mown comer'' ) being suspended in the deep well reaction vessel thereby defining a down going flow through the first pipe.
• the wet oxidation reaction of the fluid waste stream takes place in the selected reaction zone by adding an oxidant such as gaseous oxygen to the fluid waste stream.
• the oxidation reaction is exothermic, and the heat evolved by the reaction can be used to heat the influent fluid waste stream or can be collected for other use.
• organic materials are, amongst others, converted into water, carbon dioxide, dilute organic acids and ash.
• the reacted effluent waste stream is further transported in an up going flow through a passage (the up comer' ) defined by the first pipe and the reaction vessel. Finally the effluent may be further processed.
• the outlet of the oxidant feeding means is placed nearby the reaction zone.
• the oxidant already reacts with the fluid waste stream under pressure and temperature conditions that are not suitable for efficient wet oxidation.
• the outlet of the oxidant feeding means is placed just upstream of the reaction zone.
• the oxidant feeding means comprise a second pipe, which second pipe extends at least partially along the first pipe.
• the second pipe extends along the first pipe in a substantially concentric manner, preferably over a range from the inlet of the first pipe to nearby the outlet of the second pipe.
• the first pipe is at least partially thermally isolated.
• a heated down going stream through the first pipe loses heat before reaching the selected reaction zone.
• the first pipe is thermally isolated substantially over a range from the inlet of the first pipe to nearby the outlet of the oxidant feeding means .
• the first pipe can be thermally isolated by feeding an isolating fluid, preferably gaseous nitrogen, through the second pipe.
• an isolating fluid preferably gaseous nitrogen
• the inner diameter of the first pipe is substantially constant, at least over a range from the inlet of the first pipe to the reaction zone, preferably also including the reaction zone.
• the scale in the first pipe can be easily removed by mechanical means, while the risk that components are damaged is minimized, in particular when no further feeding means or sensors are suspended in the first pipe.
• the heat exchanger may be provided at any suitable position.
• the heat exchanger is preferably positioned outside of and also substantially parallel to the reaction vessel, in the subterranean hole.
• the first pipe can be cleaned without affecting the heat exchanger.
• the heat exchanger comprises a third pipe and a fourth pipe, the fourth pipe at least partially concentrically extending along the third pipe, wherein the heat exchanger can be thermally controlled by flowing an isolating fluid such as nitrogen gas (or 'any other suitable fluid) between the third and fourth pipe.
• an isolating fluid such as nitrogen gas (or 'any other suitable fluid) between the third and fourth pipe.
• the present invention relates to a method for performing a deep well wet oxidation treatment of a fluid waste stream, the method comprising the steps of: - flowing a fluid waste stream in a down going flow to a selected depth below the ground surface in a reaction vessel suspended in a subterranean hole to form a hydrostatic column of fluid exerting a selected pressure for performing a wet oxidation reaction in a selected reaction zone in the reaction vessel; - providing a selected temperature to the fluid waste stream suitable for performing a wet oxidation reaction in the selected reaction zone;
• the person skilled in the art will know how to select the conditions of temperature and pressure in the selected reaction zone at the selected depth.
• the controlling of the temperature in the reaction vessel before, during and after the wet oxidation may be obtained in any suitable manner, e.g. using a heat exchanger.
• the exact position of such a heat exchanger is not crucial as long as the objected effect is achieved.
• the fluid waste stream is flown through a first pipe being suspended in the reaction vessel.
• the first pipe and reaction vessel define a down going flow through the first pipe and an up going flow through a passage (e.g. annulus) defined by the first pipe and the reaction vessel.
• the oxidant is flown through a second pipe, the second pipe extending along the first pipe in a substantially concentric manner.
• the selected pressure in the reaction zone may be any pressure suitable for performing a wet oxidation reaction in the reaction zone. However, usually the selected pressure in the reaction zone is between 10 - 100, preferably 25 - 85, most preferably 40 - 60 bar. It has been shown that herewith an efficient wet oxidation may take place in the reaction zone.
• the selected temperature in the reaction zone may be any pressure suitable for performing a wet oxidation reaction in the reaction zone.
• the selected temperature in the reaction zone is between 180 - 340°C, preferably 250 - 300°C, most preferably 270 - 280°C.
• the fluid waste stream is only fed in the reaction vessel after the reaction zone has obtained a suitable temperature allowing efficient wet oxidation to take place. If an unheated waste stream is fed in the down comer, this may result in an ineffective oxidation. Furthermore, plugging of the down comer may occur. Therefore, preferably the selected temperature in the reaction zone is obtained by flowing a heated heating fluid through the down comer. This heating fluid may be any suitable fluid for heating up the selected reaction zone. Preferably, water is used as the heating fluid. After the reaction zone has reached the desired temperature, the fluid waste stream is fed.
• the oxidant is added to the reaction zone after the selected temperature and pressure have been obtained in the reaction zone. This results in an efficient wet oxidation in the reaction zone.
• Figure 1 a schematic cross-sectional view of the apparatus according to the present invention.
• Figures 2 - 5 schematic cross-sectional views of different phases in the wet oxidation of a fluid waste stream using the apparatus according to Fig. 1.
• FIG. 1 shows a schematic cross-sectional view of the apparatus according to the present invention for performing a deep well oxidation treatment of a fluid waste stream such as sewage sludge.
• the apparatus 1 comprises a deep well reaction vessel 2 (length: 1208 m; internal diameter 34,6 cm), which vessel 2 is suspended in a subterranean hole 3 (length: 1250 m; internal diameter: 55,9 cm) in the ground 19.
• the vessel 2 may e.g. be made from stainless steel.
• the subterranean hole is 3 filled with a heat transfer fluid (HTF) 16.
• the HTF 16 may be any suitable fluid medium, such as non-corrosive oils or demineralized water.
• the reaction vessel 2 is - in the shown embodiment through the HTF 16 (internal diameter: 10,2 cm) - in heat exchanging contact with a heat exchanger 4.
• the heat exchanger 4 is positioned outside the reaction vessel 2, but in the subterranean hole 3.
• the heat exchanger 4 extends substantially parallel to the reaction vessel 2.
• the heat exchanger 4 is in the shown embodiment in the form of an open ended pipe 17 which can be thermally controlled by a surrounding concentric pipe 18. Between the pipe 17 and the pipe 18 of the heat exchanger 4 an isolating fluid such as nitrogen gas may flow.
• the apparatus 1 further comprises a first pipe 5 (the Mown comer'; length: 1187 m; internal diameter: 18 cm) for feeding the fluid waste stream into the reaction vessel 2.
• the first pipe 5 is suspended in the reaction vessel 2. Together, the reaction vessel 2 and the first pipe 5 define during use a down going flow through the first pipe 5 and an up going flow through the annulus 6 defined by the first pipe 5 and reaction vessel 2.
• the down going and up going flowing flows are indicated with arrows .
• the apparatus 1 comprise oxidant feeding means 7 for feeding e.g. an oxidant rich gas into the first pipe 5.
• the oxidant feeding means are embodied in a second pipe that extends in a substantially concentric manner along the first pipe 5.
• the outlet 8 of the second pipe 7 is comprised in the wall of the first pipe 5.
• the outlet 8 of the second pipe 7 is placed nearby that part of the reaction vessel 2 forming in use the wet oxidation reaction zone 9.
• Figures 2 - 5 show schematic cross-sectional views of different phases in the wet oxidation of a fluid waste stream using the apparatus according to Fig. 1.
• a heated heating fluid 10 such as water is fed through the first pipe 5 in order to obtain a selected temperature in the reaction zone 9 of the reaction vessel 2.
• the selected temperature in the reaction zone 9 is between 180 - 340°C, preferably 250 - 310°C, most preferably 270 - 280°C.
• the first pipe 5 may be thermally isolated by feeding an isolating fluid 11 such as nitrogen gas through the second pipe I , in order to reduce heat loss of the heating fluid 10.
• an isolating fluid 11 such as nitrogen gas
• first pipe 5 is isolated at least over a range from the inlet 12 of the first pipe 5 to the outlet 8 of the second pipe 7.
• a fluid waste stream 13 (see Fig. 3) is fed through the same first pipe 5 thereby replacing the heating fluid 10.
• the suitable temperature may e.g. be determined by temperature sensors 20.
• the feeding of the isolating fluid 11 through the second pipe 7 is stopped. Instead an oxidant 14 such as gaseous oxygen is fed through the second pipe 7.
• the oxidant 14 enters the first pipe 5 nearby, but preferably just upstream of, the reaction zone 9.
• the fluid waste stream 13 reaches the reaction zone 9 and the wet oxidation of the fluid waste stream 13 begins.
• the temperature of the reaction zone 9 may rise.
• the temperature of the reaction zone 9 may be controlled by removing heat from the fluid 13 in the reaction zone 9 if the fluid 13 in the reaction zone 9 is above a selected temperature. Instead, heat may be added if the temperature of the fluid 14 is below a selected temperature. This may for example be done using the heat exchanger 4 and HTF 16.
• the at least partially reacted fluid waste stream 13 is transported further, through annulus 6, back up to the ground surface 15 (see Fig. 5) .
• the stream 13 may then further be processed.

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• Life Sciences & Earth Sciences (AREA)
• Hydrology & Water Resources (AREA)
• Engineering & Computer Science (AREA)
• Environmental & Geological Engineering (AREA)
• Water Supply & Treatment (AREA)
• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Treatment Of Water By Oxidation Or Reduction (AREA)

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• 2003
  • 2003-03-20 WO PCT/NL2003/000209 patent/WO2004083128A1/en not_active Ceased
  • 2003-03-20 AU AU2003304008A patent/AU2003304008A1/en not_active Abandoned
  • 2003-03-20 EP EP03816379A patent/EP1646588A1/de not_active Withdrawn

Non-Patent Citations (1)

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