JPS5884020A - Pressure variation for separation of gas mixture due to adsorption - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved pressure swing process for the continuous separation of gaseous mixtures by adsorption, which process can advantageously be used to enrich air with oxygen.

If the component to be removed from the crude product gas is present in a relatively high concentration, e.g. more than 1 volume, or it is insufficiently adsorbed by the adsorbent and as a result a large adsorption device for thermal regeneration is required. and when a large regeneration amount is required, a method using pressure swing adsorption (PC) is used. Separation by adsorption is generally carried out at pressures higher than the desorption of the adsorbed components after the adsorption step. The desorption process is most often assisted by washing the adsorbent with a portion of the product gas, for example during recovery of nitrogen from combustion gases or during gas drying. When the air is enriched with oxygen by adsorption, this washing is carried out at 1 part (absolute) for an adsorption pressure of 2 to 4 bar (absolute), and the product gas is separated (German Publication No. 1.259.844).
or part of the pressure release gas (German Publication Specification 2.5sa
964).

Molecular sieve zeolites used as adsorbents adsorb not only nitrogen but also oxygen and argon from the air.
Enriching the air with oxygen occupies a place of particular importance compared to other PC injection methods. It is therefore not possible to adsorb only nitrogen and obtain all the oxygen present in the crude product air. Since argon is adsorbed at the same slow rate as oxygen, the method of enriching air with oxygen has a residual content of argon and nitrogen of 5%.
Gives only 5% oxygen product. In the hitherto known methods, these high oxygen concentrations can only be achieved if the amount of nitrogen on the molecular sieve zeolite is kept as low as possible in the adsorption outlet zone at the end of the adsorption stage, or if this zone is filled with oxygen. It will be done.

This means that during the performance of the deposition step a valuable high percentage of oxygen is lost in the adsorption outlet zone and therefore the recovery rate for oxygen (which is proportional to the amount of oxygen in the air added to the process) is This means that the amount of oxygen) and the yield of the PC system are considerably reduced.

This applies when the adsorption is carried out under a pressure of 1 bar (absolute) and the molecular sieve is pumped away countercurrently to the adsorption using a vacuum pump. [German Publication Specification 1.26 to 724 and 1,
81suo04]. When the desorption is carried out under reduced pressure in order to enrich the air with oxygen, the desorption of nitrogen is improved by the cleaning effect of the eluate in the adsorption outlet area. The method of oxygen enrichment is considerably improved by filling the adsorber with oxygen product after depressurization to the adsorption pressure, since this gas pushes the amount of nitrogen from the adsorption outlet section into the bulk area. [German Announcement VIIM 5-1, 544.152]. Attempts have also been made to improve the cleaning effect by adding a portion of the product stream into the molecular sieve bed that needs to be desorbed [German Published Specification 2].
．． This did not result in any substantial improvement in the efficiency of the process since it involved a loss of some of the valuable product gas. The experimental results obtained in Example 1 below show that the production of 1100N"7'Ox (concentration 90%) requires an amount of molecular sieves of about 5m" per adsorber. This means that 1 of the product gas
When dividing 0% as cleaning gas, it means providing an individual amount of cleaning gas of only [LO33Nm'' per m'' of zeolite, which from experiments is far too small to produce a cleaning effect. It has been known.

The present invention provides a method for the separation of gas mixtures which eliminates these drawbacks of vacuum cleaning with a proportion of product gas and substantially improves the efficiency of the separation method by pure vacuum membrane deposition (cleaning 6 - no gas). This is a book about.

The percentage recovery of the product obtained is thereby increased, thereby improving the specific output of the vacuum pump (oxygen produced in kvh/N m") and the usage of adsorbent and crude product gas. We have found a way to reduce this.

The present invention uses at least five adsorbent beds which may be filled at the adsorbent inlet with one end containing the crude product, e.g. air, and the purified or separated product, e.g. oxygen-enriched air. , is removed at the adsorber outlet, the desorption of the nine adsorbed components is carried out at a pressure below 1 bar (absolute), and from the adsorber when it has completed its adsorption step, i.e. product release. The resulting cleaning gas is used for improved desorption, removing adsorption from the mosquito-filled adsorber in the same flow direction and simultaneously using the Ka adsorption device with subsequent connection to the crude product. The adsorption pressure can be maintained at the same adsorption pressure, or the adsorption pressure can be lowered to less than 1 pearl by closing the adsorption inlet end while the cleaning gas is being released, and this cleaning gas can be absorbed into the adsorbent (the substance to be desorbed). ) through a bed countercurrently to the direction of adsorption at a pressure of less than 1 bar (absolute).

The method according to the invention is preferably used for enriching air with oxygen. It is useful for the separation of gases and vapors whose components differ in their ability to be adsorbed, for example co! from Nl or CH4! Alternatively, it is suitable for the removal of CO, or the removal of Nl, Co or CH4 from at.

We have found a method that differs from methods previously used in terms of its improved efficiency and reduced operating costs. The structural features of the method according to the invention will now be described with reference to the accompanying drawings.
mp, 8er, Ila IX 4.6! Volume (19
73) is a diagrammatic representation of the conventional method as described on page 7, and FIG. 2 is a flowchart of the method according to the invention.

Referring further to the drawing 4I, in FIG.
12) is placed in the bulge of the adsorber.

The adsorbent bed has a storage layer, for example a silica gel, for pre-drying the gases coming at its lower end, and contains a 011 adhesive for the separation of the gas streams on top of this layer. The valve (14) for the release of the gas contained in the adsorption section and the ninth O valve (1s) for recharging the adsorber to the adsorption pressure are located at the upper end of the adsorption section. The filling of the adsorber can be regulated by a valve (15) to provide a constant increase in pressure, i.e. a constant supply of charging gas.

one! - The device of FIG. 2 differs from that of FIG. 1 in that it has an additional valve (25) and restrictor (26). The dimensional proportions of the valve are approximately indicated in the drawing. The additional valve (25) is relatively small due to the low velocity of the cleaning gas flow. The size of the cleaning gas flow can be restricted by a restrictor (26).

An essential feature of the process according to the invention is that the desorption of the adsorbent carrying adsorbent substances is carried out at a pressure of less than 1 bar (absolute) and that a separate cleaning gas stream is used. .

This cleaning gas is not part of the product gas, but is obtained from the adsorber in which its adsorption, i.e. the release of the product, has already been completed.

To obtain this gas, K keeps the adsorber removed from the adsorption stage in association with the crude gas, and removes the gas stream from the adsorption outlet at the adsorption pressure, at a low pressure in a countercurrent manner to the adsorption. It passes through the adsorption bed where it is to be desorbed.

-10- In another s41 of the method 5 according to the invention, the adsorber which has completed the adsorption stage is closed with a crude gas inlet and the gas from this adsorber is transferred countercurrently to the adsorption direction to a pressure of less than 1 par. A paper cleaning gas is obtained by passing it through an adsorption device where it is to be desorbed.

The following examples illustrate in detail the various steps of the process, and the values obtained collectively for the amount of product gas demonstrate the important effects and advantages of the cleaning process according to the invention. Ru.

Example 1 A pressure swing adsorber as shown in FIG. 1 was used. The total height of the bed in the adsorber is 2,500 cm. Each adsorber has a particle size of 25-! It contains 5-5 silica gel at the bottom which is surrounded by 5-5 molecular sieve zeolite.

Using an oil-operated rotary vacuum pump ff) with a nominal capacity of 25 m"/lli, the element-enriched air was removed from the mold applicators, B and C, and it was heated to a pressure of 1.1 to 5 bar. (Absolute pressure) K for pressurizing, compressor (R)
was provided.

A continuous process involving continuous removal of gas by Compressor (R) K was obtained using these five adsorbers.

92 steps 1: 0-60 seconds ambient air flows into adsorber A through blower (G), pipe L12 and valve 11m at a constant pressure of about 1 bar (absolute). Mourning. Oxygen-enriched air was filtered off as product at blower R through valve 14A and pipe L13. Valve 12A113A was closed. At the same time, part of the oxygen-enriched air flowed from pipe L15 through flow control valve 15, pipe L14 and valve 15B into adsorber B, whose opening valves 1411.11B and 12B were closed. Adsorber Be1, previously desorbed and depressurized
1 vote - Refilled with enriched air. Pipe L14 and valve 13 to prevent a pressure drop in adsorber A due to rapid removal of product (filling gas) through pipe L13, for example.
Constant rate of product flow into adsorber B by 11 (N-7
Valve 15 was adjusted to ensure that (expressed in hours).

During the adsorption stage in adsorber A and during the filling stage in adsorber B, adsorber C is depressurized by a vacuum pump using valve 120 and pipes 1 and 11, i.e., the valve of adsorber C 1
1C, 13C and 14C are closed. After a 60 second desorption time or one pump draw time, the mercury pressure needle placed between valve 12C and adsorber C showed a final pressure of 200 pars.

Step 2: 60-120 seconds While closing valves 11A, 15A and 14A, the adsorber was evacuated to a final pressure of 6zoo<libar by vacuum 13-pump using valve 12A and pipe L11. Adsorber BK air is charged using blower (G), pipe L12 and valve 11B, and product gas is charged to adsorber B.
was removed by a compressor (R) using valve 14B and pipe IIS. Valves 12B and 13B were closed.

Fill the adsorber CK11 with enriched air using pipe L15, flow rate control valve 15, pipe L14 and valve 15C,
As a result, the pressure in the adsorber C was increased from 200% to approximately 1%.
The adsorption pressure of the pearl was increased. At the same time, adsorber CO valves 11C, 112C and 14C were closed.

Stage 5: 120-180 seconds oxygen-enriched air is supplied to the adsorber 5 from pipe L13 to valve 15.
, using pipe L14 and valve 15m, so as to increase the pressure in the adsorber from its minimum desorption pressure (200 mbar) to an adsorption pressure of 1 bar, and on the other hand valve 11A.
, 12A and 14mu 14- were closed.

Adsorber B was depressurized to a final pressure of 200 liters by vacuum pump (V) using pipe L11 and valve 12B, while valves 11B, 13B and 14]i were closed.

Supply air enriched with adsorbent CKal elements, i.e. the same air is transferred to the adsorber CK using the blower (G), pipe L12 and valve 11C, and the product gas is transferred to the compressor (IL) and the product gas to the compressor (IL). 14C and pipe L13, and one-way valves 12C and 15C were closed.

After a 180 second cycle, the process repeats itself, ie adsorber M is adsorbing, ToL member B is filling, and adsorber C is depressurized.

After the start of the experiment (within 15 to 1 hour), a product stream with a constant degree of reactivity was obtained from the Empressor (R).9
To measure product rates at 0 gI and 80-gI oxygen content, the method was run at various product rates by adjusting the blower (G) to a bypass setting (not shown in Figure 1). Adjusted. At an oxygen concentration of 90-, 10
An oxygen product rate of 1675 Nm''7 hours was obtained based on 0-oxygen.

At an oxygen lateral change of 80-, the oxygen product based on 100 noxia is [1? ONm" It was 7 o'clock.

Example 2 FIG. 2 is a flowchart of the ninth method according to the invention for enriching draft air with oxygen by PCA technique using three adsorbers. Desorption was performed by evacuation of the adsorbent bed in countercurrent to adsorption, and at the end of desorption a second portion of the product was removed as a wash gas from the adsorber after product release was complete. . This cleaning gas was passed through the bed for desorption and adsorption in a countercurrent manner.

During this desorption step, the adsorber from which the second portion of the product was taken was kept at its previous adsorption pressure with the air inlet end held open by a valve. In the experiment of Example 1, the amount of the above cleaning gas was t? @Nw17 o'clock, that is, 1 adsorption cycle fi911Nt. The dimensions of the adsorber, adsorbent oil change, adsorption pressure, quantity and type, and dimensions of the vacuum pump were the same as in Example 1. Using the following program as a test, use the blower (G), the pipe L2ffi and the valve 21m at a fixed pressure of 1 par (absolute pressure) to the adsorber for 92 steps 1: 0-20 seconds per side. Added mourning. Oxygen-enriched air is transferred from the adsorber to valve 2.
4 and exited using a pipe LflS and was removed as product through a compressor (tR). Adsorber B is regenerated wI1. The final phase of the phase is reached, i.e. the adsorber B is depressurized by the pump (v) K using valve 22B and pipe L21, and the vacuum is reduced to 11311 [enriched air by valve 25C1 restrictor 26, It was transferred from adsorber C to adsorber 3 using pipe L24 and valve 25B. During this time, valve 21C remains open, ie, adsorber C is maintained at adsorption pressure and filled with air from the vacuum cleaner and blower (G). Valve 26 used in the experiment was a simple restrictor valve, but valve 2
K can also be designed so that 6 is adjusted to the 9th point to ensure a constant flow rate.

Valve 22m, 23m, 25A, 211, 24B.

25B, 220.2SC, 24C and 25 are closed friends.

Stage 2: 2G - 60 seconds surrounding air to blower (G), pipe L22 and valve 21A
The oxygen-enriched air continued to flow through adsorber A and was discharged from adsorber A through valve 24 and pipe L2S, and it was removed as product by a combrella (R).

18- Oxygen-rich air from adsorber BK pipe L23 to valve 2
5. Pipe L24 and valve 2SB were filled to -1 adsorption pressure.

Adsorber C was depressurized by vacuum pump ff) K using valve 220 and pipe L21. Valves 22mm, 25mm% 25mm, 21B, 22B, 24B, 25B.

210.2! IC1240 and 25C are closed.

@1fts: 60-80 seconds! The stage is similar to stage low 20 seconds, ie adsorber C is depressurized. After the release of oxygen products is completed, the oxygen-enriched air is removed from the adsorbent, and this air is used as a cleaning gas in the adsorber C, while the adsorber C is operated by a vacuum pump (V) or depressurized. Mourning. Add air to the adsorbent (G) and give oxygen-enriched air as a product, which is 1 m 9- (
R) Removed from K.

Step 4: 80-120 seconds The process step was similar to Step 20-60 seconds, ie, the adsorber was depressurized by the vacuum pump (V) K. Adsorber B produced oxygen-enriched air using a blower (G) and a compressor (R).

Air enriched with OII element was charged from adsorber CK@adsorber B until it reached adsorption pressure.

Step 5: 120-140 seconds The process step is similar to step 0-20 seconds, cleaning the adsorber A with oxygen-enriched air from the adsorber where product release has been completed, and The pressure was reduced using a vacuum pump. Adsorber CK is charged with ambient air using a blower (G) at an adsorption pressure of 1 bar (absolute), and the oxygen-enriched air is discharged from adsorber B, which is compressed by compressor (R). removed as an object.

Step 6: 14G-180 seconds process step is similar to time cycle 20-60 seconds
That is, the adsorber M is filled with oxygen-enriched air from adsorber C up to the adsorption pressure. - Side air pro * - (G
) with adsorber CK pumping, while oxygen-enriched air was discharged from adsorber C and removed as product by compressor (R) K. Adsorber B is connected to vacuum pump (v
)K, please reduce the pressure.

If the oxygen #Ik degree is 90 sq., then Ik is based on 10 tl-oxygen (L 76 Nm” 7 o'clock oxygen product is obtained. Based on the nine oxygen product series 1 is 1.02 Nm'' at 7 o'clock.

Compared to the known method of Example 1, the product rate 1 can be increased by 114% when oxygen +111 is 90- and by 7- when 1IWA#1 is 80-9.

21 - Example 3 FIG. 2 is a flowchart of a method according to the present invention for oxygen enriching PC-based air using three adsorbers. Desorption was performed by vacuuming the adsorbent bed in a countercurrent manner to adsorption. At the end of the desorption, the oxygen-enriched air or cleaning gas is removed from the adsorber in which the adsorption stage, i.e. product release, has already been completed, in the same flow direction as the adsorption. This cleaning gas was passed through the adsorber to be desorbed using a vacuum pump in a self-flowing manner, but during this desorption stage, the adsorber from which the cleaning gas was removed suffered a pressure drop because the adsorption inlet end was closed. Ta.

In Example 3, this pressure ranges from 1 par (absolute) to 77
The pressure dropped to 0 mbar (absolute). The optimum removal rate of the cleaning gas, i.e. the optimum drop in pressure, has to be determined experimentally, since it depends on the properties of the adsorbent used and the properties of the vacuum pump. .

A process program similar to that of Example 2 was used in the experiment of Example 3. The adsorber dimensions, adsorbent temperature, adsorption pressure, pressure and mold, and vacuum pump dimensions were the same as in the experiment of Example 1.

Let us briefly explain the process steps of Example 3 with respect to the first two-cycle process.

Step 1: Add air to the adsorbent for 0-20 seconds at an adsorption pressure of 1 par (absolute) using the blower (G), pipe L22 and valve 21A. Oxygen-enriched air left volume A using valve 24 and pipe L2S and was removed as product through compressor (R). Adsorber 3 has reached the final phase of its regeneration stage, i.e. adsorber B
2B and pipe L21 to vacuum pump ff) K and oxygen-enriched air was transferred from adsorber C to adsorber BK using valve 25C1 restrictor 26, pipe L24 and valve 23B. During this time, valve 21C is closed and the pressure in adsorber C drops from 1 bar (absolute) to, for example, 770 mbar (absolute).

The nine wash gases added into adsorber B did not result in a final pressure of 200 mbar at the end of the vacuum cycle as in Example 1, but the amount of wash gas resulted in a final pressure of 220-500 mbar. Valves 22A, 23m, 25m, 21B, 24B, 25B, 22C.

2SC, 24C and 25 are closed friends.

Step 2: 20-60 seconds per side air blower (G), pipe L22 and valve 21A
The oxygen-enriched air continued to flow through adsorber A through the adsorber A and was discharged from adsorber A through valve 24A and pipe L25, where it was removed as a papermaking product by compressor rR)K.

The adsorption unit 1111 is filled with oxygen-rich air up to the adsorption pressure, and the gas from the pipe L25 is adsorbed through the valve 25, pipe L24, and valve 258. 1) B11'1K is removed.

Adsorber C was depressurized by vacuum pump (V) K using valve 22c and pipe L21. Valve 22mm, 2mm, 25mm, 21B, 22B, 2411.25B.

21C, 25C, 24C and zscfi closed friends.

Stage 5: 60-80 seconds The process stage is similar to Stage 0-20 seconds, i.e. the adsorber C is empty. The inlet end of the vessel is closed (valve 21/22), and the oxygen-rich gas is depressurized in the same flow direction as adsorption, and it is adsorbed as cleaning gas. It flowed through vessel C. Adsorber Ba
Produce oxygen-rich air as a product.

Step 4: 1 IO - 120 seconds 25 One process step is similar to time 20 - 60 seconds,
That is, adsorber B distributed oxygen-enriched air, which was accepted as product by compressor (R).

The oxygen-enriched air from adsorber CK and adsorber B was filled with adsorptive pressure Kao. Adsorber A was depressurized using a vacuum pump.

Step 5: continue to depressurize the adsorber in the same way as the time cycle of 120-140 seconds 0-20 seconds, i.e. while closing the adsorption inlet end of adsorber B (valve 21B/22B), and oxygen-enriched gas was removed from adsorber B in the same flow direction as adsorption, and it flowed through the adsorber as a wash gas. Adsorber C produced oxygen-enriched air as a product.

Step 6: 140-180' second process step is similar to 20-60 second time cycle;
Thus, the adsorbed gSC produced oxygen-enriched air which was distributed as a product to the compressor (R) 26-. The absorber is filled with oxygen-enriched air from absorber C to the adsorption pressure. Adsorber B was depressurized by a vacuum pump (v).

In the experiment of Example 3, 187 was calculated based on 100919 elements.
The oxygen product rate at Nm”7 is compressor (R)
Mourning obtained at an oxygen concentration of 90%. When the oxygen concentration is 60- K, the oxygen product rate based on 100-oxygen is t02Nm''7 and 9.

Compared to the experiment from Example 1, the oxygen product rate could be increased by Ktj29 when the oxygen concentration was 90- and by 155 Is when the oxygen concentration was 801s.

Further &jL can be obtained in the 5 method according to the present invention by using 4 adsorbers. In systems using a 5-O adsorber, rounding KI! fills the adsorber to adsorption pressure. The time for adsorption is reduced by the final washing step, i.e. it is not equal to the adsorption time.

During the final cleaning period the blower (G) supplied air at a below average rate, while during the filling process it supplied air at an above average rate.

By providing four adsorbers, a constant distribution rate is obtained from the blower (G) and, as Example 4 shows, a higher oxygen production compared to, for example, the method of Example 5. The velocity of the object was obtained. However, the equipment cost for a four-adsorber system is significantly higher than that for a five-adsorber system. The four adsorber system has a relatively high specific oxygen product rate (Nwn”
For the four adsorber system, a relatively low pump energy consumption is possible for the same oxygen product rate t (Nm"7 h) due to oxygen/time x adsorber zeolite -) Overall equipment and operating costs have proven advantageous.

A program similar to Example 1 was used for the experiments in Example 4. The adsorber dimensions, adsorbent temperature, adsorption pressure, quantity and type, and vacuum pump dimensions were the same as during the experiment of Example 1 and the light.

Example 4 Stage z: o-6o seconds The adsorber supplies oxygen-enriched air, i.e. the blower (G) supplies air into the adsorber A using pipe LS2 and valve 11, and Oxygen-enriched air is released through valve 54A.
The oxygen-enriched air is discharged from the adsorber using pipe L35 and removed as a product from the combiner.
6. Fill using pipe L54 and valve 3sB, so that the pressure in collector B rises from its lowest desorption pressure to an adsorption pressure of 1 part (absolute pressure), and pipe 11-8 is filled. Vacuum pump ff) K using L31 and valve 32B
Then, the cleaning air 29 is removed from the adsorber in a countercurrent manner to the adsorption. Since valves BID and S2D are closed, the pressure in the adsorber drops from e.g. 1 bar (absolute) to 770 mbar (absolute), and the cleaning gas from the adsorber is removed from valve 35D.
, pipe L55, restrictor 39 and valve 35C were used to enter adsorber C.

Valve 32A, 35, 35A, 51B, 32B.

34B, 35B,! 5IC133C, 54C, 31D,
32D, 33D, and 54D were closed.

Stage 2: 60-120 seconds Similar to the time cycle 0-60 seconds, adsorber B distributes oxygen-enriched air and a portion of this enriched air is transferred to adsorber C for 1 perl (absolute It was used to fill up to the pressure. Vacuum was applied to the adsorber and the wash gas was removed from the adsorber and added into the adsorber.

step! i: 120-180 seconds 50 - Similar to the time cycle of 0-60 seconds, adsorber C generates oxygen-enriched air and uses a portion of it to fill the adsorber up to the adsorption pressure. Good to use.

Vacuum was applied to the adsorber and the wash gas was removed from adsorber B and added into adsorber A.

Stage 4: Similar to the time cycle of 180-240 seconds 0-60 seconds, the adsorber dispenses oxygen-enriched air, and a portion of this O-enriched air fills the adsorber to adsorption pressure. Used for rounding. Adsorber B was evacuated and the wash gas was removed from adsorber C and added into adsorber B.

In the experiment of Example 4, when the oxygen mechanical change was 90%,
Based on 1,009,152 votes an oxygen product rate of 9 α9 S Nvl/hr was obtained from the compressor (R). 8
01! In the O1l concentration conversion, the oxygen product rate based on 100-oxygen is to s Nm''7 and 9. Thus, the method of Example 4, compared to Example 1,
58% product increase at % oxygen concentration and 80%
Mourning gave an increase of 1711% in oxygen concentration.

It will be recognized that the specification and examples are presented in an illustrative and not a restrictive sense, and that various modifications may be made without departing from the spirit and scope of the invention.

[Brief explanation of the drawing]

Claims (1)

[Claims] t Desorbing the adsorbed component (5) countercurrently to the direction of adsorption at a pressure of 1 bar or less using at least five adsorbent zones, and using an adsorbent that is good for desorption. At the first loading stage, i.e., when the release of the product has been completed, the adsorber is cleaned with a gas flow drawn in the adsorption direction, and at the same time the crude gas inlet of the K11 absorber is opened and the paper machine loading pressure is maintained. or a pressure swing adsorption process for purifying and separating gaseous mixtures, which consists in reducing the pressure in the adsorber below the adsorption pressure by closing the coarsening gas inlet. 2. Process according to claim 1, characterized in that 1.2. Claims characterized by a suction pressure of 1 to 4 bar (absolute) at a constant cleaning gas dispensing pressure of 11 to 4 bar (absolute) and an occlusal pressure of less than 1 bar (absolute); The method described in Section 2. 4. Adsorption pressure of 1 to 4 bar (absolute), initial cleaning gas distribution pressure of 1 to 4 bar (absolute) and below 1 bar (absolute)
6. A method according to any one of claims 1 to 5, characterized in that the final cleaning gas dispensing pressure is (absolute pressure). & Claims 1 to 3, wherein the gaseous mixture is air.
The method described in any of Section 4. & Claim 1 substantially as set forth in the specification with particular reference to the embodiments and/or the accompanying drawings.
The method described in section.