DE1751077A1 - Process for the recovery of fuel vapors - Google Patents

Description

Pittsburgh "Fann., V.St.A.

(US 632 626 - prio 04/21/67 US 655 97 -? Prio 8.6.6) Dkt. 24-OER- 5400

Hamburg, March 27, 1968 Process for the recovery of fuel vapors

The invention relates to the use of a collection and recovery device for fuel vapors from fuel «· systems.

The release of vapors from the fuel system of automobiles is a noble of growing concern to the fuel and auto industries. The increasing air pollution has led to the fact that one has dealt with the removal of the gasoline & npfe escaping from the fuel tank and the float chamber of the carburetor, as was done, for example, in U.S. Patent J5 093 124. In the USA there are already proposals for regulations to prevent the release of gasoline fumes into the atmosphere, as these contribute significantly to air pollution (proposals from the Motor Vehicle Pollution Control Board of California and the government in the Federal Register).

In the aforementioned US patent, the use of an adsorbent, e.g. activated carbon, for the volatile gasoline components

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filled can in such a

suggest "which when the engine is stopped " toi Ct land catches and holds the petrol bowls given to the carburetor and then with the engine running again ar.-jifct and the

Motor feeds where they are burned. Adsorption will

achieved by taking the air out of the engine, or partially diii-ü ·.

the adsorbent is guided.

Based on a publication by Esbo Research and Engineering; Company ("An Adsorption-Regeneration Approach to the Problem of Evaporative Control", lecture to the Society of Automotive Engineers, Detroit, Michigan, on January 1, 1907), such a gasoline vapor adsorption system consists essentially of one of the adsorbents for gasoline vapors containing liner, 2) a pressure equalization valve and 3) elnsai external drive regulating valve. The box captures the KohlenwasserstoffdKnpfe on, - length before they can escape into the atmosphere and keeps sis se long determined to get back to the motor £ h £ egeb nv; -The may pressure equalization valve serves evd "r to keep the Dosierkräfte in the carburetor exactly on the original set Ulveau and simultaneously closing all openings to the outside, co 2α £? 3 gasoline vapors from the Schificanerkaismer of the evaporator only dt? VJr ₀ - to the adsorptive box remains open. Likewise, vapors escaping from the fuel tank are directed to the Adsorptionsbüch3e. The expulsion regulating valve enables the coals to be expelled «

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Hydrogen from the can and the supply of a stream of air laden with hydrocarbons sur Sinströmlsitursg ■ to »engine * This process only takes place under certain conditions with the engine running.

Such a collection system substantially reduces the release of burnt hydrocarbons to the atmosphere. The regulations proposed in the USA for the prevention of the release of gasoline bottles into the atmosphere provide for a limitation of the hydrocarbon losses from the carburetor to 2 g per cooling and from the fuel cafe to 6 g per day , while the losses under normal conditions ays des; Carburetor 10 g per cooling and from the Tenk 30 g per day With the Esso petrol vapor collection system, the losses from the petrol tank to 0 g per day and from the dsm carburettor to 0.9 to 1.4 g _X 1e cooling were reduced in three with motor vehicles '-uilnäsrt

will. |

In the system described in ÜSA-Patentschrift 3 093 1c'Ä , the noises released by the SchyrinsaerkatKner of the carburettor and the Bisnaintank when the engine is stopped are released again in an adsorption tube surrounding the exhaust pipe by heating the can. According to US Pat. No. 3,221,724, an adsorbent which is regenerated at a low temperature is used in such a benzine vapor on a trap system.

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When the engine is not running, the The carburetor float chamber and the fuel tank Discharge lines fed to the adsorbent and from äiei. ^ recorded and saved · When the engine is started, the air drawn in through the air inlet and the carburetor and around the adsorbent bed and bringing it to its reaction temperature, thereby removing the stored fuel vapors driven out and fed into the combustion chamber of the engine «where they are burned.

The ratio of air to fuel in the engine is appropriate in the range of 12-16ti. So far, however, there has been no way found around the can of the can with activated charcoal or the like to desorb absorbed hydrocarbons in such a way that at the beginning of the desorption process an air-fuel oemisoh with an excessively high fuel content does not get into the Kinströrsleitung to the combustion chamber. So far, ic * ner a mixture with so. high fuel content, that the engine runs irregularly and poorly, i.e. stalls and stumbles, and the carbon monoxide content is increased. This is based on the rapid hydrocarbon release during the first 10 Minutes of desorption.

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The present invention is now based on the object improved method for desorbing hydrocarbons * Steam from the adsorption canister of a gasoline vapor on f & ngsy stones to propose in which the carburettor fed to combustion Gas-air mixture is not overburdened with fuel and no air pollutants such as hydrocarbon gases can escape through the exhaust pipe. -

According to the invention, this object is achieved in that the of the adsorbents, e.g. activated carbon, in the can of one Systems such as those in U.S. Patents 3,092,124 and 3,221 or the brochure of the Esso "Evaporative Loss Control Device" described or similar devices expels adsorbed oase at different speeds.

The expulsion speed can either be infinitely variable, e.g. by using a mechanical or electrical | trisohen control device, or it can be changed in stages. For example, the change in speed in 2, 3, 4, 5 or more stages (one stepless Change in speed basically consists of an infinite number of stages). PUr most of today's Motor vehicle types, the expulsion speed is expediently set so that they are from the initial speed to

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subsequent speed is at least doubled, ie if the initial discharge wind speed is, for example, 0.003 ar / min, the following oeso speed should be at least 0.06 nr / min; expediently the following expulsion speed is 5-, 5- or ΙΟ-eel as great as the initial one. In general, the expulsion occurs initially at the lowest speed and then at higher speeds for the air being blown through.

The expulsion speed is regulated so that the ratio ▼ on fuel to air if possible always in the range of 12-16: 1 lies.

If the driving speed is not stepless but stepwise is changed, the change takes place from one speed on the other hand, preferably when the ratio of air to fuel is between 15: 1 and 16: 1.

In the following examples, activated carbon "Pittsburgh Type BPX" with a particle size of 1.65 rom to 0.42 mm (12 40 mesh US standard sieve) was used as the adsorbent, but other activated carbon such as "Pittsburgh Type BPL", "Pittsburgh Type PCB" and "Nuchar" with particle sizes of 1.65 mm to 0.60 mm (12 × 30 mesh), "Pittsburgh Type SGL" and

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"Baraeby-Cheney" has particle sizes from 2.40 ram to 0.60 mm (8 χ JO mesh), "Darco" with a particle size of 1.65 ram to 0.84 mm (12 χ 20 mesh) and the like and other adsorbents, e.g., molecular sieves can be used. However, activated carbons are preferred as adsorbents.

Since the capacity of the different types of activated carbon and other adsorbents is different, the pattern of the expulsion speeds depends depends on the particular adsorbent used. This scheme can be used for any adsorbent however, easy to set up by saturating the adsorbent with the appropriate hydrocarbon gas or gas mixture and then the rate of desorption at various rates of the air flow blown through the adsorbent canister is observed.

The speed of the air flow can also be regulated in this way will ensure that the desired desorption is achieved in a desired period of time, e.g., in 5, 10, 15 or 20 minutes. Here are of course higher overall speeds of the air flow for expelling in a time span of 5 minutes than for Expulsion of the same amount required in 20 minutes. Work with average driving times of up to 20 minutes Gasoline vapor collection systems are known to be in an experimental tent of 6 years without any noticeable change in performance

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the activated carbon. The total run through the air stream can Adsorptionsbüchse min between 0.028 nr / or the total air supply to the engine can be varied.

The invention will be explained in more detail below with reference to the accompanying drawings

Pig. 1 - the gasoline vapor according to the invention on the collecting system in a schematic Depiction;

Pig. 2 - a curve of the oas expulsion in a cumulative representation? Pig. 3 - a graph of gas expulsion in a step-by-step representation.

The gasoline collection system shown in FIG. 1 comprises a can 2 containing activated carbon, a pressure equalizing valve 4 and an expulsion regulating valve 6. In addition, a carburetor 8, an engine 10, a gasoline tank 12 and an air filter 14 are shown in connection therewith.

When the system is blown out, the hydrocarbon vapors are driven in the direction indicated by the arrows, ie the hydrocarbons desorbed by the activated carbon in the bushing are gradually desorbed and pass through the expulsion regulating valve into the engine, where they are burned. Gasoline from the fuel tank flows past the can and arrives

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also through the expulsion regulating valve into the inflow line to the engine. Petrol from the carburetor passes through the pressure equalization valve into the engine bypass to the engine, Von Outside, air is drawn through the canister at a regulated but varied speed and on its way to the expulsion regulating valve mixed with the hydrocarbons.

When the cooling engine is switched off, for example , gasoline vapors generated in the λ fuel tank are driven into the adsorption sleeve, but cannot get into the engine feed line through the expulsion valve. In the same way, gasoline vapors from the carburetor are driven through the pressure equalization valve into the can, but are prevented from entering the engine feed line.

The remaining working conditions of the gasoline vapor collection system are the same as that in the above publication

the system described by Esso Research and Engineering Company. ^

The following examples serve to further illustrate the invention. Unless otherwise noted, all quantities are based on weight.

example 1

6.995 g of activated carbon ^w BPX ^w at 25 ° C. with 1.924 g were placed in a tube

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Saturated butane vapor · From a previous experiment it was known that at an air flow velocity of 150 ml / min. 300 mg are desorbed in the first minute. Bs was expected that this amount by reducing the air flow velocity to 25 ml / min could be decreased to about 50 mg. However was found «that the expulsion took place faster than expected · So, with a consequence of the air flow, wind speeds were made from

25 ml air / min in the 1st to 3rd minute,

50 ml air / min in the 4th to 6th minute, 75 ml air / min in the 7th to 9th minute, 100 ml air / min in the 10th to 12th minute and 150 ml air / min in the 13th minute · To I5. minute

at a temperature of 25 ⁰ C the following amounts of hydrocarbons are desorbed from the activated carbon *

Table 1

Qesamtdesorptlon tent Desorption per minute Cumulative desorption min «Β mg 1 182 182 2 82 264 3 313 4th 68 381 5 60 441 6th 40 481 ϊ 524
562 9 32 59 * 10 37 631 11 30th 661 12th 699 13th 28 14th 31 758 15th 27 785

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A second experiment was carried out to show the influence of a change in the driving speed. Here warden 6.995 g of activated carbon "BPX * with 1.878 g Bufca" at 25 ⁰ C saturated Desorption was started at a Luftstroriigeschwindigkeit of 15 ml / min at 25 ⁰ C and the speed then changed as follows.:

Table 2

Air flow Time, min Desorption ever Cumulative ßchviindigkelt Minute, mg Desorption, 15 ml / min 1 105 105 η 2 68 173 11 3 45 218 η 4th 27 255 η
30 ml / min I. S. 285
J-28 η 7th 35 363 η 8th 29 392 120 ml / min 9 83 475 η 10 56 531 R. 11 46 577 150 ml / min 12th 49 626 η 3-3 41 667 η 14th 31 698 η 15th 32 730

In this process, therefore, during the desorption essentially two peaks observed * this course is a desorption with only one climax ahead-s η.

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Example 3

6.995 g of activated carbon "BFX" were mixed with 1.865 g of butane at 25 ° C saturates. The expulsion took place at 25 ° C with two air flow rates of 15 ml / mln in the first 8 minutes and 150 ml / min for the next 7 minutes. The results were as follows;

Desorption time Table 3 Cumulative desorption min Desorption per minute mg 1 mg 98 I. 2 98 160 ι T ²
42 204 5 28 232 6th 28 26p ι 23 283 9 21st 304 10 16 320 11 114 434 12th 70 504 13th 58 562 14th 44 606 15th 36 642 29 671 30th 701

example 4th

The adsorption can of a gasoline vapor collection system in a car, which contained 9I0 g of activated carbon ^M BPX " , was saturated with volatile hydrocarbon (butane). The car was driven at a speed of 50 km per hour and an air supply of 0.425 nr / min, ie 0.397 nr / min through the carburetor and 0.028 rar / min through the adsorption bushing of the gasoline vapor collection system down. the hydrocarbons votrden at 25 ⁰ C in the following amounts desorbierti

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1 75 Ί

Table 4

Tent, min

1 2

Desorption per minute, 40.9

9 10 11-15 16-20

3.4 2.4

2.5 1.7 1

(Average)

.7 () 1.2 (average)

0.425 " air at 25 ⁰ C corresponds to a weight of 475 8 air" The 0.397 w air drawn through the carburetor evaporated 27.7 g fuel per minute at an air / fuel ratio of 16: 1. The results obtained when driving the car with only this desorption rate are summarized in the following table:

Table 5

Tent, min fuel fuel total relationship from the ver from the ad fuel Air: propulsion gas, g sorption S. material can, g 1 27.7 40.9 * 68.6 6.9 2 27.7 13.3 41.0 11.6 3 27.7 8.8 36.5 13.0 4th 27.7 6.7 34.4 13.8 5 27.7 5.6
4.5 33.3 14.3 6th 27.7 3.3 32.2 14.8 7th 27.7 3.4 31.0 15.3 8th 27.7 2.4 31.1 15.3 9 27.7 2.5 * 30.1 15.8 10 27.7-. 1.7! 30.2 15.7s 11-15 27.73 1.2 * 29.4 * 16-20 27.7 * 28.9 * 16.5 * ^ Average

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After complete desorption of the fuel from the adsorption sleeve, the ratio of air to fuel was 17.2: 1.

Example 5

The same car as in Example 4 was used. The adsorption canister was filled with 910 g of activated carbon "BPX" and saturated with volatile hydrocarbon (butane). The car was driven again at a speed of 50 kra per hour. In the first 8 minutes, 0.422 sr / min of air was drawn in through the carburetor and 0.005 or / min through the adsorption canister, and in the next 7 minutes 0.425 ar / mln was drawn in through the carburetor and 0.028 or / min of air through the can The results obtained with these two different desorption speeds are shown in Table 6 below

- - ™ w fuel Table 6 Oesamt- relationship Tent, min from the ver fuel pulp Air f gas, g from the ad « S. fuel sorptlons- 29.6 büohse, £ 42.3 11.2 1 29.6 12.7 39.0 12.2 2 29.6
29.6 9.4 35.0
35.2 13.6
14.5 ι 29.6 5.4
3.6 55.2 14.5 5 29.6 3.6 52.6 14.6 6th 29.6 3.0 32.3 14.7 29.6 2.7 31.7 15.1 9 27.7 ² I ¹ 42.5 11.2 10 27.7 14.8 56.8 12.9 11
12th 27.7
27.7 9.1 55.5
55.4 13.5
14.2 13th 27.7 7.6 14.7 14th 27.7 4.6 51.4 15.2 15th 27.7 3.7 51.6 15.1 3.9

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After complete desorption of the fuel from the adsorption canister the ratio of air to fuel was X7.2 j I.

"Xn Pig, 2 shows the desorption of 6.995 g of activated carbon initially saturated with butane ^w BPX ⁿ cumulatively, with the desorbed amount of butane in mg on the ordinate and the desorption time in minutes on the abscissa the air tr gas velocity "0.028 m-vrain. On the two-speed curve, the air was drawn through for 8 minutes at 0.0028 nr / min and then for minutes at 0.0282 srVmin. In the last curve for 5 different speeds, the air was blown for 5 minutes at 0.045 rpm, then from the 4th to the 6th minute at 0.0095 rpm, then from the?. up to the 9th minute with 0.01 ^ 2 nr / miii, then vcn ck: 10th to the 12th minute with 0.0190 nr / min * 'and finally from the IJ. pulled through with 0.0285 trr / min up to the 15th minute *

In Figure 5 the desorption per minute for the same three runs is as in Pig. S shown; on the ordinate the amount of desorbed butane is plotted in rag and on the abscissa the desorpticnszoit is plotted in milligrams "

As from the. ¹ curves seen, in a: achieved -indigkeit · 'change of Austreibgessiwiiindigkeit a more uniform than in a lesorption-r · sawing Äusfcreic ;; eschv.

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Claims (8)

Pittsburgh Activated Carbon (US 632 026 - prio 21.4.6? Conpany US 655 973 - prio 8.6.67 Pittsburgh, Perm./V.St,A, Dkt. 24-OER - 5 * 00) Hamburg, 27. V & tz I968 patent claims 1. Process for recovering fuel vapors from a fuel system of an engine, in which the fuel vapors are adsorbed by an adsorbent, characterized in that the fuel vapors are desorbed-old expulsion air at different speeds and the expelled vapors are burned in the engine. 2. The method according to claim 1, characterized in that the speed of the expulsion air to at least twice the initial expulsion rate he " increases. 3. The method according to claim 1, characterized in that, the speed of the expulsion fan to at least five times the initial expulsion speed. 4. The method according to claim 1, characterized geiccnnzeiehnet that IU9 817/0 5 3 0 BATH ORIGINAL the speed of the expulsion air during the Austrcibvorgar.ges gradually and continuously increased. 5. The method according to claim 1, characterized in that »The speed of the expulsion air increased gradually and in a subsequent stage at least twice the speed of the initial speed the expulsion air applies. 6, method according to claim 5, characterized in that there are two different speeds of the expulsion air applies 7 · The method according to claim 6, characterized * that in the second stage the expulsion air with at least at five times the speed as in the first stage. 8. The method according to claim 5 "characterized" that one 2 bit 5 different speeds of the expulsion air turns. 9 · Process according to claims 1 bl3 8 ,, characterized in that that one uses activated charcoal as a means of absorption. 1 fj 'i 81 ^7/1 0 J 3 0 BAD ORIGINAL V