Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/18—Absorbing units; Liquid distributors therefor
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/1487—Removing organic compounds

Definitions

• the present invention relates to a method for treatment of hydrocarbon gases which are to be absorbed, and where these gases are pressurised to increase the efficiency of the absorption.
• VOC gases Hydrocarbon gases are often called VOC gases, where VOC means volatile organic compounds.
• the source for such hydrocarbon gases is crude oil which contains a mixture of compounds, from the volatile hydrocarbons to the heavier volatile hydrocarbons (depending on the length of the carbon chain) .
• the highly volatile compounds will evaporate and form a gas phase. It is common to feed such evaporated hydrocarbons through a circuit in which the gases are compressed and are absorbed in a hydrocarbon liquid which is then returned to the crude oil.
• the method according to the invention is in particular associated with processes of absorption in which the absorption, i.e. a condensation, takes place in an absorption column, but the invention shall not be limited to this.
• the absorption medium is often the medium which the gas originally comes from, whereupon the gas is then regenerated/recycled.
• a liquid ring compressor is a mechanical pump, which uses a liquid as a piston to compress the gas.
• Such liquid ring compressors come in several models, for example such as shown in the figures 1A and IB.
• the liquid ring compressor in figure IB comprises a closed housing or cover 10 with inlet 12 and outlet 14, and which limits a chamber 16, in which a movable part is fitted, a balanced rotor 18.
• the rotor comprises a number of vanes 20 evenly distributed around the rotor circumference, with a rotor chamber 19 being formed between each vane.
• the rotor 18 is the only movable part, and all the functions of a mechanical piston are provided by a liquid piston 22 which creates a ring form when the rotor rotates.
• the rotor which is driven by a diesel motor, electro-motor or the like, transfers power to the liquid and keep this in motion.
• the liquid will follow the inner side of the rotor housing 10 and form a ring with approximately constant thickness.
• the rotor 18 being positioned off-centre in relation to the compressor housing, the liquid will fill and empty each rotor chamber one time for each rotation. Therefore, one achieves a piston effect and gas that is conducted into the housing through the inlet 26 is compressed and conducted out through the outlet 28 as gas with higher pressure.
• a double-acting compressor is shown in figure IB.
• the compressor housing 30 has an oval shape such that where the housing is smallest, diametrically opposite compressor chambers are formed.
• the two opposite compression chambers balance side-forces on the rotor.
• water is normally used to supply the compressor housing and forms the liquid ring in the housing.
• One of these concerns bringing another (foreign) medium or material into the system.
• much of the liquid in the liquid ring follows the pressurised gas to the absorption column itself, and the water must be separated in its own separator.
• One part of the liquid is cooled and is re-circulated afresh through the liquid ring compressor.
• the method according to the invention is characterised in that the liquid ring used in the liquid ring compressor comprises the absorption medium.
• the specially preferred embodiments of the method are described in the dependent claims 2-5.
• the device is characterised in that the liquid ring comprises the absorption medium.
• the absorption starts in the compressor. Improved efficiency is achieved through associated pipes and installation of an absorption column. None of the components in the gas or liquid will change chemical composition according to the present invention.
• the present method for compression will be considerably simpler than corresponding methods with other liquids or compressor types. In other words, the main object is completely different to GB 1,408,124.
• the device and method are applied in the processing of combustible VOC gases. Tanks that contain variable amounts of combustible liquids emit VOC gases, which are collected and are conducted into the system.
• the absorption medium can be the same liquid which the gas comes from, or a corresponding liquid.
• the former case relates to occasions when the absorption liquid is conducted back to the same tank, which continuously emits the VOC gases.
• the latter case relates to occasions when the absorption liquid is not fed back to such a VOC emitting tank, but is handled separately in another installation.
• the absorption medium itself as a liquid ring By using the absorption medium itself as a liquid ring, one achieves a number of advantages.
• the liquid in the liquid ring compressor is a part of the absorption medium which is to be mixed with the gas from the absorption column. It is therefore not necessary to separate the liquid from the gas after compression. This leads to a considerable simplification in the process and saving in equipment.
• the object of this process is to absorb as much as possible of the gas in the absorption medium.
• a good infusion of the gas already in the liquid ring compressor is an advantage as a further infusion of the absorption medium will take place in the absorption column.
• the separation of the gas and liquid after compression is unnecessary. Nor will a chemical reaction or conversion occur after the compression.
• the invented method and device can be used in most absorption processes.
• the savings and advantages are many:
• a robust compressor type i.e. a liquid ring compressor which is not sensitive to what is sucked in, i.e. that the compressor accepts gas, liquid and to some extent small solid particles.
• Exhaust gases such as combustible hydrocarbons (VOC gases) are conducted into the system by way of the pipe 10 and directly in through pipe 60 to the liquid ring compressor 20, which includes a liquid ring of the same material as the absorption medium in the absorption column 40.
• VOC gases combustible hydrocarbons
• the absorption medium is conducted through pipe 1 and pump 2 to pipe 3, whereupon it is split into two streams, 4 and 5.
• Pipe 4 supplies the absorption medium to the liquid ring compressor.
• the stream is split in two where pipe 6 supplies liquid continuously to the liquid ring, and pipe 7 sprays absorption medium into the gas for cooling and start of the absorption process.
• the pressured gas which brings with it liquid from the liquid ring, is diverted from the liquid ring compressor 20 through pipe 62 and further into the absorption column 40, where the pressurised gas rises up through a layer of absorption medium supplied through pipe 5.
• the VOC depleted gas is led further out from the top of the column 40 through pipe 42 and to air 44.
• the absorption medium enriched with gas is led out through pipe 41.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Analytical Chemistry (AREA)
• General Chemical & Material Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Gas Separation By Absorption (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=19912032

Family Applications (1)

Country Status (2)

Cited By (7)

Citations (4)

• 2001
  • 2001-01-19 NO NO20010345A patent/NO20010345L/no unknown
• 2002
  • 2002-01-21 WO PCT/NO2002/000027 patent/WO2002062452A1/en not_active Application Discontinuation

Patent Citations (4)

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