RU2571766C1 - Gas scrubbing method and device - Google Patents

Abstract

FIELD: oil and gas industry.

SUBSTANCE: mixture of gas and liquid is passed through a centrifugal separator. From the separator the scrubbed gas is output separately from washing liquid and liquid is returned to the vat section for circulation purpose. Gas is supplied to direct-flow centrifugal scrubber elements placed at direct-flow centrifugal plate. At that gas is warped thus creating vacuum zone in near-axial zone of the element. Liquid is supplied from vat section due to difference in pressure under the section of centrifugal separation and at the axis of centrifugal scrubber element. Liquid is supplied through vertical washing liquid feed tubes, which one end is fixed in near-axial zone of direct-flow centrifugal scrubber elements while the other end is lowered to liquid in the vat section.

EFFECT: developed effective method and device of gas scrubbing with liquid supplied without pump thus reducing energy consumption costs and quantity of washing liquid.

3 cl, 2 dwg

Description

The group of inventions relates to the gas, gas processing, oil, chemical industries and can be used in processes and apparatus for separating liquids and separating solids from a gas stream, for example, in schemes for preparing gas for transport, at field facilities during the period of falling pressure, connecting booster compressor stations (DKS), in schemes for taking gas from underground storage facilities (UGS), etc.

A known method of drying gas (copyright certificate No. 965486 from 11.0601981, IPC ⁵ B01D 53/26), including primary gas separation, contacting the gas with an absorbent and stripping moisture from a saturated absorbent and its subsequent condensation.

In the contactor installed in the bottom part of the absorber, water stripped from the glycol regenerator is used to wash the salts, followed by gas separation from the washing liquid.

The disadvantages of this method of drying gas are:

- the presence of a constantly operating high-pressure pump for supplying liquid (flushing water) to the high pressure contactor;

- the need for constant withdrawal and disposal of the spent solution of washing liquid;

- increased energy costs for the implementation of the process.

A device for carrying out the washing process is known: Scrubber - droplet eliminator (RF patent No. 2379092 dated 12.12.2007, B01D 45/12), including a housing with anticorrosive lining, inlet and outlet gas pipes, as well as an emulsifier, droplet eliminator, made in the form of an annular grating and radially spaced blades and conical bottom, and the supply of hot air.

The ends of the droplet eliminator blades are biased towards the flow twist.

The disadvantage of this device is:

- the need for a constant supply of fluid to the scapular ring dust collector;

- the need for constant removal of flushing fluid and its disposal;

- the presence of an emulsifier;

- the presence of an emulsifier drive;

- increased energy costs.

A known method and device for wet cleaning of gases (RF patent No. 2121866 from 12.22.1993, IPC ⁶ B01D 47/06) (prototypes), irrigated in the pipeline with washing liquid, in which the resulting gas-liquid mixture is passed through a cyclone separator and purified from the separator gas is removed separately from the flushing fluid. A device for wet cleaning of gases, containing a gas supply channel having at least one nozzle device for supplying a washing liquid in communication with a cyclone separator, from which the purified gas and, separately from it, a washing liquid containing impurities are discharged.

In this method, the preliminary washing of the gas in the accelerating channel is carried out in several stages, and then the gas-liquid mixture is fed to the washing in a centrifugal separator. This method increases the washing efficiency by using several successively installed washing sections.

The disadvantage of this method and device is:

- increased hydraulic resistance to gas due to the passage of gas through the accelerating channel;

- increased hydraulic resistance to gas leads to increased energy costs.

The technical result of the group of inventions is to create an effective method and device without pumping gas washing with liquid.

A single technical result in the implementation of the group of inventions on the subject - the method is achieved by the fact that in the method of wet cleaning of gases with a washing liquid, the resulting gas-liquid mixture is passed through a centrifugal separator and the purified gas is removed from the separator separately from the washing liquid, while the liquid is supplied to the axial part a centrifugal separator from its bottom part due to the energy from the pressure drop formed by the centrifugal separator, and after contact of the liquid with gas it is returned to the bottom part to the compass It is an indication that the height of the column of fluid supply to the centrifugal separator is less than the column of its hydraulic resistance.

A single technical result in the implementation of the group of inventions on the object - the device is achieved by the fact that in the device for wet cleaning of gases, containing a gas supply channel in communication with a centrifugal separator, from which the purified gas is removed and the washing liquid is removed separately, while the contaminated liquid is removed into the bottom part of the separator for recirculation - feeding into a centrifugal separator.

Liquid supply without a pump, having a pressure equal to the gas pressure directly from the bottom part to the axial part of the centrifugal separator due to the energy from the pressure drop formed by the centrifugal separator, made it possible to exclude the pump for constant supply of flushing liquid from low pressure to the pressure in the separator, which significantly reduced energy consumption of the washing process.

The supply of fluid to the axial part of the centrifugal separator with its return after contact to the bottom part allowed to reduce the amount of washing liquid, because it is used until it is completely saturated with impurities due to recirculation.

By changing the hydraulic resistance of the centrifugal separator, for example, the number of centrifugal separation elements, it is possible to change the height of the column of fluid supply to the centrifugal separator.

The removal of contaminated flushing fluid into the bottom part of the separator for recirculation - feeding into a centrifugal separator made it possible to exclude the pump for constant supply of fluid to the centrifugal separator.

The authors are not aware of gas separation methods and devices for their implementation, in which gas flushing without pumps would be carried out in a similar way.

In FIG. 1 is a diagram illustrating a gas flushing method; FIG. 2 - device for wet gas purification.

The object is a gas flushing method according to the scheme shown in FIG. 1, consists of the following technological sections:

I - section collection of separated impurities;

II - section for collecting washing liquid;

III - section centrifugal washing (mass transfer) and separation;

IV - section for the separation of gas from the flushing fluid.

A gas or gas-liquid stream G ₀ with mechanical impurities (Fig. 1) is sent under the centrifugal washing and separation section III, from where flows g are fed to the direct-flow centrifugal scrubber elements (PCCE) 7 for contact with the washing liquid supplied by flows I _i due to the difference pressures under the centrifugal separation section and on the axis of the PCCE, through the supply pipes of washing fluid 8 to the PCSC from the washing fluid collection section II. The pressure drop is formed from the gas resistance in the centrifugal flushing section III and from the decrease in pressure on the axis of the PCCE due to centrifugal forces from swirling gas flows. Liquid impurities after contact with the gas by discharge channels 10 flows currents I _f in the section collecting the washing liquid, wherein the heavy phase, including mechanical impurities settle and flow into the section gathering the separated impurities I, and the washing liquid streams I _i recycled (fed ) in the supply pipe of the washing fluid 8 in PCCE. The liquid flows from the PCCE are returned to the centrifugal washing plate 6, and the gas flows from the elements by the flows g ₀ are fed to the separation section from the washing liquid IV, from which the purified gas flows by the g ₁ flows into the outlet pipe of the purified gas 3, from where it is taken off by the flow G, and the separated washing liquid flows 1 _p returns to the centrifugal washing section III on the centrifugal washing plate 6.

When the level of the washing liquid drops to the bottom of the tubes for supplying the washing liquid 8 to the PCCE, they are replenished through the nozzle of filling the bottom part of the separator with washing liquid 4.

The impurities separated from the gas are discharged through the flushing fluid sampling pipe with impurities 5.

An example of the method

Gas consumption, nm ³ / h - (105000 ÷ 1150000);

Pressure, MPa - (0.35 ÷ 0.55);

Temperature, ° C - 8;

The flow rate of flushing fluid per working volume of gas, t / h - (3.0 ÷ 7.8);

The amount of mechanical impurities, kg / h - (2.31 ÷ 2.53);

Pressure drop across the flushing section, Pa - (1780 ÷ 3300).

The object device is a device for wet gas purification (Fig. 2) contains:

- building 1;

- pipe inlet of the gas mixture 2;

- outlet pipe of the purified gas 3;

- a nozzle for filling the bottom part of the separator with washing liquid 4;

- nozzle for selection of washing liquid with impurities 5;

- centrifugal flushing plate 6;

- direct-flow centrifugal scrubber element (PTsSE) 7;

- tubes for supplying washing liquid 8 to PCCE;

- separation section for collecting the washing liquid 9;

- drain channels 10.

The crude gas is fed into the separator housing 1 through the inlet of the gas-liquid mixture 2 and distributed along the annular passage, where, due to inertia and gravity, the primary gas is separated from large particles.

Next, the gas is fed to PCCE 7 located on a centrifugal washing plate 6 inside the annular passage, and the gas is washed from solids by a circulating liquid. In PTsSE 7, gas is twisted, creating a rarefaction zone in the axial zone of the element, which allows the liquid to be supplied from the bottom part of the separator, including and due to the pressure drop on the centrifugal flushing plate 6 to the low pressure zone of the PTsSE 7. The liquid is lifted through a vertical tube 8, one end of which is fixed in the near-axis zone of the TsPSE 7, and the other is lowered into the liquid of the bottom part of the apparatus body 1. The liquid is sent to PCCE 7 and discarded to its inner walls, where the washing liquid is mixed with mechanical impurities, and the gas stream is directed along the center axis. Mechanical impurities and a liquid with a part of the gas are taken to a centrifugal washing plate 6. The gas sampled with mechanical impurities and the liquid is combined with the purified gas coming from the central zone of the PCCE 7 and then sent to the separation section for collecting the washing liquid 9, from where the purified gas is discharged through the outlet pipe purified gas 3. The selected liquid with mechanical impurities from the centrifugal washing plate 6 is discharged through the drain channels 10 into the still bottom, where it is accumulated and periodically removed from a parator through a nozzle for selecting washing liquid with impurities 5. A nozzle for filling the bottom part of the separator with washing liquid 4 is used when filling and when it is necessary to replenish the device.

For example, water can be used as a washing liquid, and for the northern regions antifreeze - an aqueous solution of methanol or glycol, or Arctic hydrocarbon fuel.

Thus, the use of this invention will reduce the energy consumption of the washing process when supplying liquid without a pump due to the energy from the pressure difference formed by the centrifugal separator from low pressure to the pressure in the separator, and the liquid supply to the axial part of the centrifugal separator with its return after contact to the bottom part will reduce the amount of flushing fluid.

Claims (3)

1. A method of wet cleaning of gases with a washing liquid, in which the resulting gas-liquid mixture is passed through a centrifugal separator, the purified gas is removed from the separator separately from the washing liquid, and the liquid is returned to the bottom part for circulation, characterized in that the gas is supplied to direct-flow centrifugal scrubber elements located on a centrifugal direct-flow plate, while the gas is twisted, creating a rarefaction zone in the axial zone of the element, the liquid is supplied from the bottom part due to the pressure difference under the section centrifugal separation and on the axis of the centrifugal scrubber element. 2. The method of wet cleaning of gases with washing liquid according to claim 1, characterized in that the height of the column of fluid supply to the centrifugal separator is less than the column of its hydraulic resistance. 3. A device for wet gas purification, containing a gas supply channel in communication with a centrifugal separator, from which the purified gas is discharged and the washing liquid is diverted separately to the bottoms for recirculation, characterized in that it contains several centrifugal scrubbing elements located on the centrifugal washing plate vertical tubes for supplying washing liquid, one end of which is fixed in the axial zone of the direct-flow centrifugal scrubber elements, and the other is lowered into the bottoms liquid sti, and drain channels for draining the liquid from the centrifugal flushing plate into the bottom part.

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