US20110290371A1

US20110290371A1 - Miniaturized Plant for Producing Gas Mixtures

Info

Publication number: US20110290371A1
Application number: US13/119,037
Authority: US
Inventors: Jean-Paul Barbier; Steffen Richter; Hervé Durand; Hans Hiller; Joachim Barbe
Original assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2008-09-16
Filing date: 2009-09-01
Publication date: 2011-12-01
Also published as: FR2936038A1; JP2012503147A; CN102159869A; FR2936038B1; CA2735845A1; EP2324276A1; AU2009294494A1; WO2010031940A1; WO2010031940A8; ZA201101592B

Abstract

The invention relates to a plant for filling gas cylinders with pure gases and/or mixtures of pure gases or special gases, said plant including: a device for selecting gas and/or for making mixtures of gases to be fed into a gas cylinder; apparatuses for analyzing the composition of said mixtures or said pure gases; characterized in that the following measures are implemented: the plant is integrally contained in a transportable container having a ground surface lower than 45 m², said ground surface preferably being between 34 m²and 40 m²; the devices contained in said container are attached to the walls of the container and can be connected to gas sources outside the container; the arrangement thus obtained enables the users to access said devices and apparatuses from the inside of said container and to fill the cylinders inside said container.

Description

The present invention relates to plants for filling cylinders with pure industrial gases or mixtures of pure gases or of special gases.
The gases involved in such filling operations are, for example:

- those taken from the air (N₂, Ar, O₂), helium, hydrogen and mixtures thereof in concentrations typically at the percent level with other gases, when the cylinders are filled in “batches” (several cylinders at a time).
- carbon dioxide or nitrous oxide, the cylinders of which are filled by weighing, one cylinder at a time.

The mixtures of special gases are mixtures of compressed or liquefied gases in cylinders, which mixtures are notably characterized by the following aspects:

- great accuracy regarding the concentration of the constituents;
- a great many constituents, sometimes several tens of constituents, such as, for example, the hydrocarbon mixtures used in refinery and the petrochemical industry;
- the difficulty in maintaining the stability of the concentration of the constituents when these are reactive toward the walls of the cylinder especially if their concentration is low.

These are therefore mixtures which are very accurate in terms of the compositions and/or which contain very low contents of compositions, these contents being at the ppm level.
These characteristics entail complex production equipment in order, notably:

- to clear and passivate the inside of the cylinders that are to be filled, so as to obtain concentrations of constituents that are reactive toward the walls of the cylinders which remain stable over time;
- to produce mixtures with a high degree of accuracy regarding the concentration of the constituents;
- to control the composition of the mixtures.

Incorporating such equipment into a production plant requires specialist design studies and suitable buildings (for example buildings with controlled temperature). The lead times involved in the design phase and the cost of appropriate buildings are great. In particular, the costs are too high if the market is too small or sometimes difficult to justify because of a risky economic environment and a little-known market or an unstable economic climate.
Moreover, it has been found that the sophistication of plants is evolving rapidly. The industrial world is increasingly switching over from so-called heavy industry to units producing consumer products and goods. This is leading first to a change in the size of plants and second to a call for increasingly sophisticated very different production machinery originating from highly varied geographic locations.
Whether a plant is to be big or small, simple or complex, the approach followed when building such a plant has remained conventionally the same. “Turnkey” solutions are very often employed. These have the advantage to industry of forcing the supplier or suppliers to comply with a preset technical and financial objective and thus guarantee industry (the end user customer) results. In consequence, the production of a plant as a “turnkey” solution is organized as follows:
First of all, the production machinery is built at various existing plants, for example in already-developed countries.
These various machines are sent over land or by sea to the final site.
These machines are set up in a traditional or prefabricated building that has already been erected on the final site.
The machines are set up and connected together (fluid, electricity, pipe work, etc.) inside the building on the final site.
The machines are tested on the final site prior to start-up.
This conventional method involving distant turnkey industrial units, for example situated in developing countries, does have a good number of uncontrollable factors associated with it. All that is needed is for the ordered equipment to arrive when the erection of the building on the final site has been delayed and there is a risk that this equipment will remain in crates for several months or even more. This leads to degradation of the machinery and requires expensive reconditioning.
Problems arise just as frequently if the machines are not all delivered within the agreed deadline. A missing element in the middle of the line can prevent a plant or a part of a plant from being started up in its entirety.
With this conventional turnkey plant solution, several partners generally share in the project at various stages and at locations which are geographically remote from one another. The production plant appoints equipment specialists to supervise the setting-up, start-up and final acceptance phases. The design and production engineering concern appoints specialist engineers for the detailed design, set-up drawings and testing. This results in numerous communication problems. This is particularly the case when the industrial end user or a local company has adopted responsibility for erecting the building and installing the equipment.
By transferring the plants around it is possible to reduce the production costs and more effectively amortise the investments for new industrial entities. However, the current situation is essentially restricted to providing the option of transporting the various machines, respective internal receptacles of the type used generally for goods that can be moved around by sea or by road (using trucks). That does not reduce the times and costs below certain limits because the machines have to be loaded into the receptacles and removed therefrom and then the production line has to be reassembled.
One technical problem addressed by the present invention is therefore that of providing a plant for the industrial production of mixtures of pure gases or of special gases, which plant can be dismantled, transported and reassembled simply and quickly.
As will be seen in greater detail in what follows, the plant proposed by the invention is notable in that, in order to achieve such flexibility:

- the plant is a “miniature” plant such as can be contained in a container of very small size and nonetheless, given the gases being handled, it needs to offer first-rate temperature, accuracy and safety conditions,
- the plant is operational: in other words, the operators need to be able to enter it, work in it, move around in it and perform handling operations, doing all of this inside the plant and in a space which is nonetheless restricted in order to limit the movements of the cylinders,
- for that, the essential equipment that makes up the plant is secured to a wall of the container, so as to allow the operators to be able to move around inside the plant while carrying out all the necessary operations, including the moving-around of the cylinders,
- the plant preferably comprises a ventilation system which on the one hand provides control over the temperature inside the container, this being so as to allow work to take place inside the container irrespective of the temperature outside but also so as to allow accurate mixtures to be created by measuring the pressure-temperature of the components of the mixtures, and the ventilation system also allowing any accidental leaks of toxic and/or flammable gases to be diluted in the internal atmosphere of the container so that there are no damaging consequences.

Included among the essential equipment that makes up the plant and that is secured to a wall of the container there are, in particular, items of apparatus for the vacuum drying of the cylinders prior to first filling, for removing residual gases from the cylinders before they are refilled, for producing mixtures, for purifying gases, and analyzers, etc.
It may be noted that the prior art contains documents such as documents EP-366 559 and WO 2006/123373 which describe containers that can be transported by sea or by land and contain machinery intended to be used in a plant; said containers, once combined with one another in an arrangement that is to be defined, form a true plant.
Thus, by way of illustration, WO 2006/123373 relates to an arrangement of containers containing apparatus needed for the intended production method (it is aimed first and foremost at the manufacture of insulating panels even though it cites other possible applications such as the “packaging of liquid products”, without anywhere describing the special case of the production of gaseous mixtures and its filling into cylinders. However, and above all, it does not describe a plant that the operators can enter, and in which they can move around, produce a product, move the cylinders around in a miniaturized space because quite clearly the author anticipates the presence of empty containers “adjacent” to the plant allowing operators access to “the production plant” and quite logically the walls of these containers are then open and in communication. It can therefore be clearly seen from the above that WO 2006/123373 is concerned with a quite different type of plant and quite logically WO 2006/123373 is not facing the same set of problems and therefore is not in any way proposing a solution that technically addresses the problems now presented.
One subject of the present invention is therefore a plant for filling cylinders with gas using pure gases and/or mixtures of pure gases or of special gases, comprising:

- equipment for selecting gases and/or for producing mixtures of gases intended to be introduced into a gas cylinder,
- apparatus for analyzing the composition of said mixtures or of said pure gases;
  characterized by the use of the following measures:
- the plant is wholly contained in a transportable container, the footprint of which is less than 45 m2, and preferably the footprint ranges between 34 m²and 40 m²;
- the equipment and apparatus contained in said container is attached to the walls of the container and able to be connected to gas sources situated outside the container;
  the arrangement thus produced allowing the personnel using it to access this equipment and apparatus from inside said container and proceed with said filling of the cylinders inside said container.

Moreover, the plant according to the invention may adopt one or more of the following features:

- the plant comprises two parts,
  - i) a first part comprising:
- equipment for producing mixtures of pure gases or of special gases intended to be introduced into a gas cylinder,
- apparatus for analyzing the composition of said mixtures of special gases or pure gases,
  - j) the other part (3) comprising:
- at least one emptying means for emptying out residual gases contained in the cylinders that are to be filled,
- at least one means of cleaning and/or of passivating the cylinders that are to be filled,
- at least one means for homogenizing the produced mixtures.
  - In substance, the plant may then be made up of a single container containing the two parts in question or alternatively of two containers placed end to end, and communicating, there being one container for each of the two parts involved.
- the two parts are separated from one another by a movable wall.
- said first part further comprises a means of controlling the interior temperature.
- the equipment for producing mixtures comprises at least one mixer associated with at least one analyzer.
  - the equipment for producing mixtures comprises:
    - a weighing apparatus and/or manometric apparatus each able to measure accurately the quantities of gas to be introduced into the cylinder,
    - a means of connection between the cylinder that is to be filled and gas sources situated, preferably, outside the container.
  - the equipment for producing mixtures comprises at least one line set able to produce any type of compressed or liquid gas mixtures.
  - the weighing apparatus situated in the container is positioned on a support independent of the container and the base of which is situated below the container floor level.
  - the plant comprises at least one apparatus for analyzing the composition of the mixture, chosen from:
    - at least one gas chromatograph intended to separate the various constituents of a mixture;
    - at least one thermal conductivity detector (TCD) or flame ionization detector (FID);
    - at least one oxygen analyzer;
    - at least one moisture analyzer;
    - at least one infrared spectrometer for determining the concentration of certain compounds in a mixture.

As will have been understood from reading about the sizings preferred by the invention, preference is given to ISO containers and it will be recalled that:

- a 20-foot ISO container measures 6 m×2.4 m=14.4 m²
- a 40-foot ISO container measures 12 m×2.4 m=28.8 m²

According to preferred implementations of the invention, the plant comprises a single 40-foot ISO container or, alternatively, 2 ISO containers:

- one 20-foot ISO container for the internal preparation of the cylinders, and
- a 40-foot ISO container for producing and analyzing the mixtures.

As was mentioned earlier on in the present description, the plant preferably comprises a ventilation system which on the one hand provides control over the temperature inside the container, this being so as to allow work to take place inside the container irrespective of the temperature outside but also so as to allow accurate mixtures to be created by measuring the pressure-temperature of the components of the mixtures, and the ventilation system also allowing any accidental leaks of toxic and/or flammable gases to be diluted in the internal atmosphere of the container so that there are no damaging consequences.
It will have been understood that this system is especially well justified for the handling of flammable gases (such as H₂. . . . ) or toxic gases (such as CO, H₂S, NO₂. . . ). Further, the objective of its presence is therefore to avoid the build-up of such gases inside the container.
Such a build-up could of course result only from an accidental leak because, as will have been appreciated, in such plants that handle toxic and/or flammable gases, every step is also taken to limit such risks (vents that vent to the outside, filters, collective valves, use of high-pressure equipment, use of corrosion-resistant materials, etc., which measures are well known to those skilled in the art).
Depending on the gases handled it is possible of course to conceive of numerous configurations and positioning of the extraction points, particularly whether these are in a low position and/or in a high position in order to collect gases that are heavier and also those that are lighter than air.
Detection of the presence of a toxic or flammable gas, for example by detectors located inside the vents that discharge to the outside of the container, will lead to chosen actions including: an increase in the air renewal flow rate, visible or audible alarms, the cutting-off of the electrical power supplied to most of the container equipment with the exception of the forced ventilation equipment and emergency lighting, etc.
According to one of the embodiments of the invention, the plant comprises two parts:

- i) a first part housing the equipment for producing the mixtures and the apparatus for analyzing the composition of the mixtures, and
- j) a second part that can be termed the “cylinder preparation” part housing the equipment for emptying out the residual gases contained in the cylinders that are to be filled, means for cleaning and/or passivating the bottles that are to be filled, means for homogenizing the produced mixtures,
  and the plant also comprises a ventilation system comprising:
- in the “cylinder preparation” 2nd part, two independent forced ventilation blowers, one for ventilating the entirety of this 2nd part, the other ventilation blower situated specifically above the location of the cylinders which are in the emptying phase;
- and in the “mixture production” 1st part, two independent forced ventilation blowers, one to ventilate the entirety of this 1st part and the other ventilation blower situated specifically above each station at which a cylinder is in the process of being filled or analyzed.

Another subject of the invention is a method of preparing a mixture of special gases in a cylinder implementing a plant as defined hereinabove connected to at least two sources of special gases external to the plant.
According to one of the embodiments of the method of the invention, the cylinder that is to be filled is connected to just one gas source at a time.
According to one of the embodiments of the method of the invention, it comprises the steps:

- of preparing the cylinder that is to be filled;
- of filling said cylinder by connecting it to a source of gas, using a weighing apparatus and/or manometric apparatus each able to measure accurately the quantities of gas to be introduced into said cylinder;
- of analyzing the composition of the content of the cylinder thus filled.

The container used may be an ISO container that can be transported, for example, by land and by sea. Thus it is possible to standardize the manufacture of the complete plant at a factory in order to optimize production costs, and to withdraw the container/plant if necessary and transport it to a more suitable location in order to recoup the investment.
Contrary to the prior art documents cited hereinabove, the equipment contained in the container is attached to the walls of the container. Specifically, the components such as, for example, the production equipment or the analysis apparatus is fixed to the walls of the container containing the plant according to the invention. As already explained hereinabove, on the one hand such an arrangement allows the users to access this equipment from inside the container while at the same time allowing this equipment to be connected together and, on the other hand, to gas sources situated outside the container, using piping attached to the walls of the container. This affords a certain space saving and therefore allows the plant to be better miniaturized, but also ensures better stability of measurements thanks to the securing of the apparatus.
By way of illustration, the plant may be placed inside an ISO container measuring 12 meters long, 3 meters wide and high, or alternatively two ISO containers measuring 6 meters long positioned end to end.
It should be noted that, according to the prior art, both in terms of the filling of pure gases and of the filling of mixtures of pure or special gases, the quantity of gas to be filled and the quantities of raw materials needed mean that a large-sized building housing the filling plant has always hitherto been considered.

Other specifics and advantages will become apparent from reading the following description which is given with reference to the figures in which:

FIG. 1 is a diagram of one example of how a plant according to the invention is organized;

FIG. 2 is a diagram of equipment for producing mixtures of special gases included in a plant according to the invention.

FIG. 1 depicts a plant 1 according to the invention for producing mixtures of special gases, comprising two parts 2 and 3. The two parts are separated by a movable wall 20. For example, the movable wall 20 is a sliding door. FIG. 1 illustrates the case of an embodiment in a single container divided into two parts connected by a movable wall, but it is equally possible according to the invention to conceive of an embodiment in which the two parts consist of two ISO containers joined together.
The first “mixture production” part 2 has an interior temperature controlled by a temperature control means. For example, such a means is a heating or an air conditioning system.
Said part 2 houses the equipment 4 used for producing the mixtures and the apparatus used for analyzing the composition of the mixtures here situated in zone 5.
One example of equipment 4 for producing said mixtures is depicted in FIG. 2.
Accurate measurement, for example using manometry, of the quantities of gases to be mixed is preferably carried out using equipment and cylinders for filling in a temperature-controlled space. This controlled temperature aspect is an essential feature in obtaining appreciable reliability and accuracy on an industrial scale. Temperature control is needed for the production of accurate mixtures using a barometric method.
The “cylinder preparation” part 3 comprises at least one means 6 of emptying out the residual gases contained in the cylinders that are to be filled, at least a means 8 of cleaning and/or passivating the cylinders that are to be filled, and at least one means 9 of homogenizing the produced mixtures. The plant 1 is wholly contained in a transportable container 10 the footprint of which measures less than 45 m², the footprint preferably ranging between 34 m²and 40 m². The height of the container 10 is, for example, between 2.5 meters and 3.5 meters, and the height is preferably 3 meters.
In practice, personnel enter the container via a door 11 and proceed with filling the cylinders 7 situated initially in the part 3 and intended for the preparation (cleaning, passivation, emptying) of the cylinders 7. Said filling of the mixtures is performed in part 2, the temperature of which is controlled, using the mixture production equipment 4.
The cylinder 7 intended to be filled with a mixture of special gases is first of all prepared, if necessary, for example by cleaning using the cleaning and/or passivating means 8, and/or by emptying out the residual gases from the cylinder if this cylinder has already been used, using an emptying means 6.
If it has already been used, said cylinder will therefore probably be contaminated with residual gases. The passivation means 8 is, for example, an oven into which the cylinder 7 is introduced for a few hours. Once the cylinder 7 is ready, the user takes possession of it then rolls or alternatively carries it to the temperature-controlled part 2 of the plant. The user can then proceed with filling the mixture of special gases into the cylinder 7 thus prepared. When several cylinders are ready, the user can transport several at a time in order to optimize his work time and productivity and stow said cylinders at a dedicated location 11.
The mixture production equipment 4 is depicted schematically in FIG. 2. The cylinders intended to be filled are each connected to one and the same filling line set 12 by connection means 14. This filling line set 12 is connected to a control panel 13, for example a CLP. This filling line set 12 is connected to automatic valves 22 which are connected to measurement instruments, for example to the weight measurement formulated by the weighing system 17 so that when the weight of gas to be introduced into the cylinder is reached, the valve closes automatically.
The filling line set 12 is also connected to a network 15 of sources of special gases which is located outside the container 10 in which the plant according to the invention is located, as depicted in FIG. 1. According to one of the embodiments of the invention which is of special benefit in terms of safety, when a cylinder is in the process of being filled, this cylinder is connected to just one single gas source at a time. This is because it is preferable, in order to avoid an explosion, for a source of flammable gas not to be connected at the same time as a source of oxidizing gas to said cylinder while it is in the process of being filled. The fact that the filling line set 12 is able to fill the cylinders with any family of mixtures may entail a cleaning of said line set 12, particularly a cleaning of the connection volume. Such a line set 12 may be a single line set according to one embodiment of the invention. The same line set 12 is able to fill the cylinders with mixtures such as, for example, mixtures of flammable gases/inert gases, oxidizing gases/inert gases, oxidants/fuels. A safety system (not depicted) that prevents the production of mixtures of incompatible gases in the equipment may also be added to the container 10.
The quantities of special gases that make up the mixture are measured and checked using measurement and checking means such as a manometer 16 and a weighing system 17. Depending on the degree of accuracy desired for the production of the desired mixture, the equipment 4 comprises either a manometer 16 and a weighing system 17, or just one of these two. Said mixture producing equipment 4 is situated in the temperature-controlled part 2 of the container 10 and so the stable temperature allows the pressure to be measured reliably.
In order to avoid measurements being perturbed for example as a result of vibrations on the floor of the container 10, the weighing system 17 here is arranged on a support 18 independent of said container 10. The base of the support 18 is situated below the container 10 floor level. For example, this base of the support 18 of the system 17 rests on a chassis welded to the container 10 independently of the chassis carrying the floor of the container 10, so as to limit as far as possible any vibrations incurred by, for example, people or bottles moving around.
Once the mixture has been created, it is analyzed using analysis apparatus situated in zone 5 of the container 10. The analysis apparatus is, for example:

- gas chromatographs intended to separate the various constituents in a mixture. The concentration of the constituents in the mixtures is measured by means of detectors which vary according to the type of constituent and the concentration thereof. The detectors most commonly used are thermal conductivity detectors (TCD) or flame ionization detectors (FID) in the case of hydrocarbon compounds;
- oxygen analyzers;
- moisture analyzers;
- infrared spectrometers for determining the concentration of certain compounds in a mixture.

It is good to note that the layout of the components in the plant according to the invention is such that the user moves around as little as possible. The cylinders do not therefore have to be moved very much. Further, the space between the production equipment 4 and the analysis apparatus is large enough that the user can move around but small enough for the plant to be miniaturized as far as possible thus limiting the movements of cylinders.
Moreover, such a plant requires only a very low number of personnel to run it. By comparison with real-size plants in existence at the present time, the number of individuals working on the plant 1 according to the invention is very small and the distance required for the transportation of cylinders during the mixture filling process is reduced to the minimum.
When analysis is complete, the cylinders filled with mixtures of special gases are transported to part 3 of the container 10 to what is known as a homogenizing means 9. Said means 9 is, for example, a cylinder roller.
It is possible that a mixture of gases at the end of the filling of a cylinder will not have a homogenous composition throughout the cylinder when, for example, the cylinder is filled in a vertical position and when the constituent introduced last is of a lower density than the previous constituents. One way of homogenizing the mixture is to place the cylinder in a horizontal position and to revolve it about its axis at a speed of several revolutions per minute for a minimum of ten minutes or so.
The means 6, 8 and 9 are automated.
When this operation is complete, the user takes the cylinder filled with the desired gas mixture out of the container 10 and sets it down at a storage site 19 whence a batch of cylinders will be transported to the customer. The storage site 19 is, for example, situated outside the container 10.
One embodiment of the plant 1 according to the invention may be restricted to the manufacture of just a few cylinders of mixtures per day, for example 8 cylinders per eight-hour working day or the equivalent of 2000 cylinders per year, considering mixtures containing three compounds on average. This type of plant is therefore capable of supplying a market corresponding to the needs of several refineries and/or petrochemical industries and/or car plants.
As has been stated, FIG. 1 illustrates the situation in which the plant comprises two parts:

- i) a first part 2 housing the equipment used to produce the mixtures and the apparatus used for analyzing the composition of the mixtures, and
- j) a second part 3 housing the equipment that could be termed “cylinder preparation” equipment notably including means of emptying out residual gases contained in the cylinders that are to be filled, means of cleaning and/or passivating the cylinders that are to be filled, means of homogenizing the mixtures produced,
  and according to one of the embodiments of the invention, the plant also comprises a ventilation system comprising:
- in the “cylinder preparation” part 3, two independent forced ventilation blowers, one for ventilating the entirety of this 2nd part 3, and the other ventilation blower situated specifically above the site of the cylinders in the emptying phase.

By way of illustration and to give a better feel for the invention, practical examples of flow rates are given here, with:

- for the ventilation of the entirety of the “cylinder preparation” part 3, an air flow rate in normal operation of 150 Nm³/h corresponding to 5 renewals per hour, and of 800 Nm³/h if a toxic or flammable leak is detected.
- for the ventilation above the cylinders being emptied, under normal operating conditions a ventilation flow rate of 100 Nm³/h for each cylinder is applied with, on the whole, 1200 Nm³/h if a toxic or flammable leak is detected.
- in the “mixture production” part 2, there are two independent forced ventilation blowers, one for ventilating the entirety of this 1st part 2, the other ventilation blower being situated specifically above each station at which a cylinder is in the filling or analysis phase.

- for the ventilation of the entirety of the “mixture production” part 2, an air flow rate in normal operation of 300 Nm³/h corresponding to 5 renewals per hour, and of 1200 Nm³/h if a toxic or flammable leak is detected.
- for the ventilation above the cylinders being emptied or analyzed, under normal operating conditions a ventilation flow rate of 100 Nm³/h for each cylinder is applied with, on the whole, 1600 Nm³/h if a toxic or flammable leak is detected.

The raw materials used for producing these mixtures, which may be flammable and/or toxic gases, are positioned in sources connected to the equipment 4, 13, 12 of the plant 1 from the outside. This saves space in the ISO container 10 and makes it easier to manage the risks of ignition and explosion in the event of leaks of flammable gas from the cylinders.
This plant 1 is capable of producing mixtures of special gases required by the key users: refineries, petrochemical plants, the automotive industry and research laboratories for example.
Said plant according to the invention can also advantageously be used as a plant for conducting tests on limited numbers of cylinders and if these tests prove conclusive, a decision may be made to install a larger sized plant in order to increase production.
By way of example, here are some non-exhaustive lists of mixtures of special gases that can be produced by the plant according to the invention.
Examples of Mixtures for Analysis Apparatus:


	5% or 10% of CH₄in argon
	2% or 5% of H₂in argon
	40% of H₂in helium
	10% of CO₂in argon
	5% of CO₂in oxygen
	5% of CO₂/5% or 10% of H₂in nitrogen
	10% of CO₂/10% of H₂in nitrogen
	40% or 45% of H₂in nitrogen

Examples of Mixtures for Measuring Atmospheric Pollution:


	Composition	Concentration

	NH₃in N ₂	15 ppm
	HCl in N ₂	10 to 45 ppm
	CO in N₂	45 to 9000 ppm
	H₂S in N₂	5 to 1000 ppm
	NO in N₂	8 to 1800 ppm
	C₃H₈in air	3 to 3000 ppm
	CO in air	9 to 15 ppm
	NO₂in air	9 to 450 ppm
	SO₂in air	28 to 500 ppm
	NO/NO_xin N₂	40 to 1000 ppm

Examples of Hydrocarbon Mixtures Used in Refinery and Petrochemical Plants:


	Mixtures of gaseous hydrocarbons (2 to 10 components)
	Mixtures of liquid hydrocarbons (2 to 10 components)

Claims

1-12. (canceled)

13. A plant for filling cylinders with gas using pure gases and/or mixtures of pure gases or of special gases, comprising:

a) equipment capable of selecting gases and/or of producing mixtures of gases intended to be introduced into a gas cylinder, and

b) an apparatus capable of analyzing the composition of said mixtures or of said pure gases;

wherein the plant is wholly contained in a transportable container, the footprint of which is less than 45 m²;

wherein the equipment and the apparatus are attached to a wall of the transportable container;

wherein the transportable container is configured to permit the equipment and the apparatus to be connected to gas sources situated outside the container; and

wherein the equipment and the apparatus are configured within the transportable container such that personnel are capable of accessing and operating the equipment and the apparatus from inside the transportable container to fill cylinders.

14. The plant of claim 13, comprising two parts:

i) a first part comprising:

equipment configured to produce mixtures of pure gases or of special gases, and

the apparatus capable of analyzing the composition of said mixtures of special gases or pure gases,

j) the second part comprising:

at least one emptying device adapted to empty out residual gases contained in cylinders that are to be filled,

at least one device adapted to clean and/or of passivate the cylinders that are to be filled,

at least one device capable of homogenizing the mixtures of pure gases or of special gases.

15. The plant of claim 14, wherein the two parts are separated from one another by a movable wall.

16. The plant of claim 14, wherein said first part further comprises an apparatus adapted to control the interior temperature.

17. The plant of claim 13, wherein the equipment configured to produce mixtures of pure gases or of special gases comprises at least one mixer associated with at least one analyzer.

18. The plant of claim 13, wherein the equipment configured to produce mixtures of pure gases or of special gases comprises:

a weighing apparatus and/or manometric apparatus each able to measure accurately the quantities of gas to be introduced into said cylinder, and

a fluid connection between the cylinder that is to be filled and gas sources situated outside the container.

19. The plant of claim 18, wherein the equipment configured to produce mixtures of pure gases or of special gases comprises at least one line set able to produce any type of compressed or liquid gas mixtures.

20. The plant of claim 18, wherein the weighing apparatus situated in the transportable container is positioned on a support which is independent of the container, the support having a base situated below the container floor level.

21. The plant of claim 13, wherein it comprises at least one apparatus capable of analyzing the composition of said mixtures or of said pure gases, chosen from:

at least one gas chromatograph;

a thermal conductivity detector (TCD);

a flame ionization detector (FID);

an oxygen analyzer;

a moisture analyzer; or

an infrared spectrometer.

22. The method of preparing a mixture of special gases in a cylinder implementing a plant as defined in claim 14 connected to at least two sources of special gases external to the plant comprising the steps:

preparing the cylinder that is to be filled;

using a weighing apparatus and/or manometric apparatus each able to measure accurately the quantities of gas to be introduced into said cylinder;

filling said cylinder by connecting it to a source of gas, and

analyzing the composition of the content of the cylinder thus filled.

23. The method of claim 22, wherein the cylinder that is to be filled is connected to just one gas source at a time.