ExxonMobil Upstream Research Company v Shell Internationale Research Maatschappij B.V
[2016] APO 27
•11 May 2016
IP AUSTRALIA
AUSTRALIAN PATENT OFFICE
ExxonMobil Upstream Research Company v Shell Internationale Research Maatschappij B.V.
[2016] APO 27
Patent Application: 2012261477
Title:Process for removing contaminants from natural gas
Patent Applicant: Shell Internationale Research Maatschappij B.V.
Opponent: ExxonMobil Upstream Research Company
Delegate: Dr S.D. Barker
Decision Date: 11 May 2016
Hearing Date: 6 April 2016, in Canberra
Catchwords: PATENTS – opposition to the grant of a patent – earlier decision in relation to parent application – novelty decided in line with earlier decision – new evidence in relation to inventive step – lack of inventive step in light of Engdahl because it would be a matter of routine to adopt a single process using the method as described and exemplified – opposition succeeds – costs awarded
Representation: Counsel for the applicant: Katrina Howard SC
Patent attorney for the applicant: Andrew Lee
Counsel for the opponent: Guy Provan
Patent attorney for the opponent: Richard Baddeley
IP AUSTRALIA
AUSTRALIAN PATENT OFFICE
Patent Application: 2012261477
Title:Process for removing contaminants from natural gas
Patent Applicant: Shell Internationale Research Maatschappij B.V.
Date of Decision: 11 May 2016
DECISION
Claims 1, 3, 22, 23, 24, 28, 29, 31 lack inventive step in light of the Engdahl patent.
I allow the applicant two months to propose amendments to overcome this deficiency.
I award costs according to Schedule 8 against Shell Internationale Research Maatschappij B.V.
REASONS FOR DECISION
Patent application number 2012261477 (the present application) was filed on 4 December 2012 as a divisional application from 2004209623 (the parent application), which claims priority from AU 2003900534 (the basic application) filed on 7 February 2003. The applicant is Shell Internationale Research Maatschappij B.V. (the applicant).
The present application was examined and accepted by the Commissioner, and subsequently opposed under section 59 of the Patents Act 1990 (the Act) by ExxonMobil Upstream Research Company (the opponent). A hearing was held on 6 April 2016 in Canberra to decide the opposition. I subsequently allowed the parties further time after the hearing to address a specific matter (discussed below under the heading of Inventive step).
The parent application
The parent application was the subject of an opposition by the opponent. That opposition was heard and a decision issued on 23 August 2012 (the earlier decision).[1] The delegate found that the opposition succeeded on the ground of fair basis, and was not successful on the grounds of novelty and inventive step.
[1] ExxonMobil Upstream Research Company v Shell Internationale Research Maatschappij B.V. [2012] APO 92.
Claim 1 of the parent application as considered by the delegate was worded identically to claim 1 of the present application.
The earlier decision addressed many of the same issues as in the present opposition. This raises a question of the extent to which the earlier decision is relevant to the present opposition. I recently considered the question of whether an estoppel (either issue estoppel or Anshun estoppel) could apply to opposition proceedings.[2] I concluded that estoppel does not apply, but that the findings of fact made in an earlier decision can be taken into account and weighed along with material that is in evidence:
"However, evidence has been filed by the parties as part of the evidence procedures laid down in the Regulations. That material is properly in evidence and is available to me to consider. However, the weight to give to that evidence, and how to weigh that against the findings of fact that have been made in the Federal Court decision, is a matter for me to decide. I consider that I should start with the findings of fact made in the Federal Court decision, and then ask whether there is any evidence that contradicts those findings of fact. Where there is contradictory evidence I will need to decide how much weight to give to each. Further, to the extent that the present opposition raises a ground not considered in the Federal Court decision (that is, lack of inventive step), the evidence filed in the present opposition will assume greater significance."[3]
[2] SNF (Australia) Pty Ltd v Ciba Specialty Chemicals Water Treatments Limited [2016] APO 8.
[3] [2016] APO 8 at [52].
The parties agreed that I should adopt the same approach in the present matter. I will start with the findings of fact made by the delegate in the earlier decision. Where there is evidence available to me that contradicts those findings of fact, I will decide how much weight to give to each. However, where the present opposition raises issues not considered in the earlier decision, the evidence filed in the present opposition will assume greater significance.
The opposition
The statement of grounds and particulars identified three grounds of opposition: novelty, inventive step, fair basis. At the hearing, all grounds were pressed.
In addition, the opponent submitted that the present applicant is not entitled to claim priority from the parent application, or the basic application. The correct determination of the priority date is not a ground of opposition, but is an essential step in the determination of the grounds of novelty and inventive step. I will discuss it briefly at a later point in the decision.
The parties relied upon evidence by several declarants. Evidence in support consists of declarations by Costa Tsesmelis and Jaime H. Valencia. Evidence in answer consists of declarations by Craig Francis Dugan and Andrew W Lee. The Lee declaration is a vehicle to annex copies of declarations that were previously filed as evidence in the opposition to the parent application (those declarations are recited in the earlier decision). Evidence in reply consists of a declaration by P. Scott Northrop. I will refer to the relevant parts of the evidence where appropriate. However, as will become apparent, the evidence as a whole is of little assistance.
The specification
The specification relates to the processing of natural gas to remove contaminants. The specification ends with three Figures and 31 claims. Claim 1 is the only independent claim. Claim 25 is not dependent on any claim, and is an omnibus claim that refers to Figures 1 and 2. The full set of claims appears at the end of this decision.
What is the invention as described
The principles of construction of specifications are well established. A succinct summary is provided by Middleton J in Eli Lilly and Company Limited v Apotex Pty Ltd:[4]
"It is well settled that the Court should, from the outset, approach the task of patent construction with a generous measure of common sense. The Court must place itself in the position of a person skilled in the relevant art, being the subject matter of the patent. From this perspective, the patent is to be read as a whole, in the context of the specification and in light of the prevailing common general knowledge and state of the relevant art at the priority date."
[4] [2013] FCA 214, 100 IPR 451 at [139].
The background to the invention
The invention relates to the treatment of natural gas so as to remove water (i.e. dehydration) and to remove acids (particularly carbon dioxide and hydrogen sulphide). Acids are generally understood to be sour species, so the removal of acids is a process of sweetening the gas.
The specification commences with a broad statement:
"The present invention relates to a process for removing contaminants, for example hydrogen sulphide or carbon dioxide when the contaminant is a sour species from a natural gas feed stream including water and sour species.
The present invention also relates particularly, though not exclusively, to a process and apparatus for sequentially dehydrating and sweetening the natural gas feed stream."
The aim of the invention
The specification acknowledges that it is "common practice for the natural gas to be subjected to a dehydration process prior to the liquefaction."[5] Methods of removing acidic components are also "known in the art, such processes typically include adsorption using solid adsorption processes or absorption using amine processes, molecular sieves, etc."[6] However, the known processes of dehydration and sweetening "are extremely complex and expensive."[7]
[5] AU 2012261477 at page 1.
[6] AU 2012261477 at page 2.
[7] AU 2012261477 at page 2.
The aim of the invention is stated to be:
"an alternative process for removing contaminants from a natural gas feed stream including water and sour species."[8]
[8] AU 2012261477 at page 2.
It seems to me that the alternative process should be one that is not as complex or expensive as the prior art.
The nature of the invention
The broadest statement of the invention appears on page 2 of the specification:
"In accordance with the present invention, there is provided a process for removing contaminants from a natural gas feed stream including water and sour species, which process comprises the steps of dehydrating the natural gas feed stream in a first vessel; removing from the first vessel a stream of dehydrated gas; cooling by means of expansion the dehydrated gas in a second vessel to a second operating temperature at which solids of the sour species are formed; and removing from the second vessel a stream of dehydrated sweetened gas."
The invention is further described by reference to three hand drawn figures. Figure 2 is shown here:
The important features of this drawing are the two large vessels towards the middle. Dehydration takes place in vessel 12 (the large vessel to the left). Sweetening takes place in vessel 14 (the large vessel to the right). Cooling takes place through expansion by Joule-Thompson valve 48. The dried, sweetened gas exits through outlet 62 and liquid containing sour species is withdrawn through outlet 52.
In its simplest form, the invention involves the steps of dehydration and sweetening, wherein the sweetening is achieved by cooling by expansion. It is not necessary to dwell on the finer details at this time.
Construction of claim 1
The correct approach to the construction of claims was discussed by Bennett J in H Lundbeck A/S v Alphapharm Pty Ltd:[9]
"the words in a claim should be read through the eyes of the skilled addressee in the context in which they appear … while the claims define the monopoly claimed in the words of the patentee's choosing, the specification should be read as a whole … it is not permissible to read into a claim an additional integer or limitation to vary or qualify the claim by reference to the body of the specification … terms in the claim which are unclear may be defined or clarified by reference to the body of the specification"
[9] [2009] FCAFC 70, 81 IPR 228 at [118] – [120].
Turning to the claims of the present application, claim 1 is the independent claim. It reads:
A process for removing contaminants from a natural gas feed stream including water and sour species, which process comprises the steps of dehydrating the natural gas feed stream in a first vessel; removing from the first vessel a stream of dehydrated gas; cooling by means of expansion the dehydrated gas in a second vessel to a second operating temperature at which solids of the sour species are formed; and removing from the second vessel a stream of dehydrated sweetened gas.
This claim contains several terms that warrant consideration. Those terms are "process", "operating temperature", "vessel", and "cooling by means of expansion".
The claim is directed to a "process". In the earlier decision the delegate said at paragraph [53]:
"Claim 1 is to a 'process', i.e. a single process, that sequentially achieves dehydration with CO2/H2S removal using two vessels".
I agree that the process is characterised by the two steps of dehydration and removal of sour species in different vessels.
The term "operating temperature" is defined in the specification as follows:
"The term 'operating temperature' is used to refer to a temperature below the solid/liquid transition temperature for the contaminant at a given pressure of operation of the first or second vessel."[10]
[10] AU 2012261477 at page 2.
I consider that this is dictionary definition that applies to this term in the claim.
The term "vessel" was considered in the earlier decision. The delegate decided that the term means "a container used as a structural envelope"[11]. I accept that the same meaning should apply to the present specification.
[11] [2012] APO 92 at [51].
Finally, I turn to the term "cooling by means of expansion". It is the dehydrated gas that is cooled, so this cooling step takes place after the dehydration step (and excludes any cooling that may be part of the dehydration process). The aim of the cooling is to achieve the second operating temperature. But is expansion the sole means of cooling used to achieve the second operating temperature, or is it possible that there is a subsequent cooling after the expansion?
The relevant words of the claim are:
"cooling by means of expansion … to a second operating temperature at which solids of the sour species are formed"
Thus the cooling is "to" the second operating temperature. This means that the cooling by expansion itself leads to the second temperature. It is not necessary for the gas to be further cooled in order to achieve the temperature at which sour species solidify.
Construction of claim 25
Claim 25 is an omnibus claim that reads:
A process for removing contaminants from a natural gas feed stream including water and sour species comprising the steps, substantially as hereinbefore described with reference to the examples and figures 1 and 2.
Claim 25 was not discussed in the earlier decision. The claim is directed to a process of removing water and sour species from a natural gas feed stream. The features of the process are "as hereinbefore described", which is clearly a reference to the body of the description. The process as described has already been discussed, and it is broadly the same as that in claim 1. Thus I consider that the features of claim 25 are dehydration in a first vessel following by sweetening in a second vessel by means of cooling by expansion to a second operating temperature.
These features are limited by reference to the examples and figures 1 and 2. Figure 1 shows an arrangement for dehydration. Figure 2 is reproduced above, and shows an arrangement for both dehydration and sweetening. These figures are further discussed in the text on pages 2 to 8. There are no examples as such in the specification, but I take the reference in the claims to "examples" to be the text explaining the figures. I note that the arrangement in the figures involves the use of flash tanks, and heat exchangers. The explanatory text discloses an explanation of the way the process operates that is not apparent from the figures alone.
Without considering the fine details of claim 25 (some of which will considered later), it is sufficient to say that claim 25 is a narrow claim that falls within the scope of claim 1.
The person skilled in the art
It is well established that many of the issues in an opposition are answered by reference to the person skilled in the art:
"He is the person to whom the patent is addressed and who must construe it. He is the person whose knowledge will determine whether a patent is novel. He is the person who will judge whether a patent is obvious."[12]
[12] Root Quality Pty Ltd v Root Control Technologies Pty Ltd [2000] FCA 980 at [70].
However, they are an artificial construct that is used as a tool of analysis, and there is a danger in trying to identify them as an actual person or persons:
"The notional person is not an avatar for expert witnesses whose testimony is accepted by the court. It is a pale shadow of a real person – a tool of analysis which guides the court in determining, by reference to expert and other evidence, whether an invention as claimed does not involve an inventive step."[13]
[13] AstraZeneca AB v Apotex Pty Ltd [2015] HCA 30 at [23].
Our understanding of the person skilled in the art is based on evidence from persons with knowledge of the art as to the things that they know and do, and what they understand to be commonly known and done. The weighing and evaluating of this evidence to decide the characteristics of the person skilled in the art is part of the normal work of a delegate of the Commissioner.
In the present case there is evidence by a number of people with experience in chemical engineering, particularly the processing of natural gas. The parties variously submit that their declarants should be given greater weight than those of the other party. I do not think that a blanket decision can be made as to which declarant is to be preferred. Rather, to the extent that there is any disagreement between the declarants I will weigh their evidence on the relevant matters.
Priority date
The opponent's argument that the present application is not entitled to priority from the parent application (and thus also from the basic application) is based on changes to the text of the specification between the parent and the present application. For instance, in the parent application it was essential that dehydration was by means of formation of hydrates.[14] That limitation is not present in the present application. Consequently, the present application is broader in scope than the parent application. In this situation it is normal to treat the present application as if it were a separate claim to each form of the invention (dehydration by formation of hydrates, and dehydration by other means) as envisaged by section 43. Different priority dates can be accorded to different forms of the invention. Since the actual priority date of any claim is not material in the present case I have not undertaken a detailed consideration. It is likely that different priority dates apply to different forms of the invention.
[14] [2012] APO 92 at [48].
Novelty
It is a requirement of subsection 18(1) of the Act that the invention, so far as claimed in any claim, is novel. Subsection 7(1) states that an invention is taken to be novel unless it is not novel in the light of the prior art:
For the purposes of this Act, an invention is to be taken to be novel when compared with the prior art base unless it is not novel in the light of any one of the following kinds of information, each of which must be considered separately:
(a)prior art information (other than that mentioned in paragraph (c)) made publicly available in a single document or through doing a single act;
(b)prior art information (other than that mentioned in paragraph (c)) made publicly available in 2 or more related documents, or through doing 2 or more related acts, if the relationship between the documents or acts is such that a person skilled in the relevant art would treat them as a single source of that information;
(c)prior art information contained in a single specification of the kind mentioned in subparagraph (b)(ii) of the definition of prior art base in Schedule 1.
A citation is part of the prior art base for the purposes of novelty if it was published before the priority date of the claim.
It is well established that the general test for lack of novelty is the reverse infringement test. The classic formulation of this test is that given by Aickin J in Meyers Taylor Pty Ltd v Vicarr Industries Ltd:[15]
"The basic test for anticipation or want of novelty is the same as that for infringement and generally one can properly ask oneself whether the alleged anticipation would, if the patent were valid, constitute an infringement"
[15] [1977] HCA 19 at [20], 137 CLR 228 at 235.
This test is satisfied if the alleged anticipation discloses all the essential features of the invention as claimed (see Nicaro Holdings Pty Ltd v Martin Engineering Co[16]).
[16] (1990) 91 ALR 513 at 517.
The opponent relied on two citations to allege lack of novelty: US 4,533,372 (Valencia) and US 5,819,555 (Engdahl).
US 4,533,372 (Valencia)
Valencia was published on 6 August 1985. Consequently it is part of the prior art base.
Valencia was considered by the delegate in the earlier decision (referred to as D1 in that matter). The delegate found that the disclosure of Valencia was:
"D1 describes what is referred to as a controlled freeze zone, CFZ™, process in which the feedstream is treated in at least one distillation zone and a controlled freezing zone. The freezing zone produces carbon dioxide slush which is melted and fed into a distillation section"[17]
and
"D1 relies on solid formation through contact with liquid spray from nozzles … This feature is different to opposed claim 1, where cooling of the gas is by means of expansion to a second operating temperature at which solids of the sour species are formed."[18]
[17] [2012] APO 92 at [79].
[18] [2012] APO 92 at [83].
This led the delegate to conclude that:
"The invention of claim 1 is distinguished over the disclosure of D1 in both the manner in which solids are formed, and in that the claim is directed to a sequential process for dehydrating and sweetening natural gas, which is not the object of D1."[19]
[19] [2012] APO 92 at [88].
The delegate also found that the manner in which solids are formed in the second vessel is different to the invention as claimed.[20] I have no compelling evidence that would lead me to revisit the conclusion of the delegate in the earlier decision. I find that claim 1 of the present application (and the appended claims) and claim 25 have not been shown to lack novelty in light of Valencia.
[20] [2012] APO 92 at [83].
US 5,819,555 (Engdahl)
Engdahl was published on 13 October 1998. Consequently it is part of the prior art base.
Engdahl was considered by the delegate in the earlier decision (referred to as D2 in that matter). The delegate found that the disclosure of Engdahl was:
"D2 discloses a process to remove carbon dioxide from a natural gas feed by cooling the contaminant gas to form a solid. However, in this citation as with D1, the process starts at the point where dried feed gas is fed into the system … D2 does not disclose a single process for removing contaminants including water and sour species where sequential dehydration and sweetening is carried out in two separate vessels, the first step providing feed for the second step."[21]
[21] [2012] APO 92 at [93].
The delegate focussed mainly on whether the process was a single process, concluding it was not. I have reviewed the evidence and can find nothing significant on this point, so there is no reason to come to a conclusion different to that of the delegate. I find that claim 1 of the present application (and the appended claims) and claim 25 have not been shown to lack novelty in light of Engdahl.
Inventive step
It is a requirement of subsection 18(1) of the Act that the invention, so far as claimed in any claim, involves an inventive step. Subsection 7(2) states that an invention is taken to involve an inventive step unless it would have been obvious to a person skilled in the art in the light of the common general knowledge, considered alone or together with the prior art:
For the purposes of this Act, an invention is to be taken to involve an inventive step when compared with the prior art base unless the invention would have been obvious to a person skilled in the relevant art in the light of the common general knowledge as it existed in the patent area before the priority date of the relevant claim, whether that knowledge is considered separately or together with the information mentioned in subsection (3).
Subsection (3) prescribes the information that may be considered as:
The information for the purposes of subsection (2) is:
(a)any single piece of prior art information; or
(b)a combination of any 2 or more pieces of prior art information;
being information that the skilled person mentioned in subsection (2) could, before the priority date of the relevant claim, be reasonably expected to have ascertained, understood, regarded as relevant and, in the case of information mentioned in paragraph (b), combined as mentioned in that paragraph.
Once the common general knowledge and relevant information has been identified, the test for whether an invention is obvious is to ask whether it would have been a matter of routine to proceed to the claimed invention. In Wellcome Foundation Ltd v V.R. Laboratories (Aust.) Pty Ltd[22] Aickin J stated:
"The test is whether the hypothetical addressee faced with the same problem would have taken as a matter of routine whatever steps might have led from the prior art to the invention, whether they be the steps of the inventor or not."
[22] [1981] HCA 12 at [45], 148 CLR 262 at 286.
The High Court in Aktiebolaget Hassle v Alphapharm Pty Ltd (Hassle)[23] approved this approach. Matters of routine are to be distinguished from other courses of action:
"The tracing of a course of action which was complex and detailed, as well as laborious, with a good deal of trial and error, with dead ends and the retracing of steps is not the taking of routine steps to which the hypothetical formulator was taken as a matter of course."[24]
[23] [2002] HCA 59, 212 CLR 411.
[24] [2002] HCA 59 at [58].
The opponent pressed lack of inventive step in the light of the common general knowledge, or three documents:
·the Engdahl patent
·the Valencia patent
·R.C. Haut et al "Development and application of the Controlled-Freeze-Zone process" SPE Production Engineering (August 1989) 265 – 271 (the Haut article)
The problem
In the earlier decision the delegate said the problem was:
"the complexity and expense associated with prior art means of removing contaminants whether these contaminants are water, sour species or both".[25]
[25] [2012] APO 92 at [109].
While there have been some amendments to the specification of the present application, I consider that this is still a fair statement of the problem – an alternative means to remove contaminants from natural gas.
The common general knowledge
Common general knowledge is the background knowledge and experience available to all those working in the relevant art:
"The notion of common general knowledge itself involves the use of that which is known or used by those in the relevant trade. It forms the background knowledge and experience which is available to all in the trade in considering the making of new products, or the making of improvements in old, and it must be treated as being used by an individual as a general body of knowledge."[26]
[26] Minnesota Mining & Manufacturing Co v Beiersdorf (Australia) Ltd [1980] HCA 9 at [115]; (1980) 144 CLR 253 at 292.
It is not enough that information is recorded in a document, even one that is widely circulated. It is only part of the common general knowledge when it is generally known and accepted:
"information does not constitute common general knowledge merely because it might be found, for example, in a journal, even if widely read by persons in the art … Reference in this regard is made to the words of Luxmoore J in British Acoustic Films (1936) 53 RPC 221 at 250, cited by Lehane J in Aktiebolaget Hässle v Alphapharm Pty Ltd (1999) 44 IPR 593; [1999] FCA 628 at 605 [39]:
In my judgment it is not sufficient to prove common general knowledge that a particular disclosure is made in an article, or series of articles, in a scientific journal, no matter how wide the circulation of that journal may be, in the absence of any evidence that the disclosure is accepted generally by those who are engaged in the art to which the disclosure relates. A piece of particular knowledge as disclosed in a scientific paper does not become common general knowledge merely because it is widely read, and still less because it is widely circulated. Such a piece of knowledge only becomes general knowledge when it is generally known and accepted without question by the bulk of those who are engaged in the particular art; in other words, when it becomes part of their common stock of knowledge relating to the art."[27]
[27] Ranbaxy v AstraZeneca [2013] FCA 368; (2013) 101 IPR 11 at [217].
In the earlier decision, the delegate found that the following matters were common general knowledge:
"There is no dispute as to the following matters being common general knowledge before the priority date (from applicant's submissions):
(a) CFZ process for removing CO2 from natural gas (Dugan 3.6 – 3.9)
(b) LTX process used to achieve hydrocarbon dew point control (Dugan 3.6, 3.12 – 3.13)
(c) Ryan-Holmes process to remove acid gases such as CO2 using adsorption (Dugan 3.6, 3.10 – 3.11)
(d) dehydration of a natural gas feed stream by various processes (Dugan 3.3 – 3.5)"[28]
[28] [2012] APO 92 at [111].
The parties accepted that this was a correct conclusion, and I agree that the same conclusion applies in the present opposition.
Obviousness in light of the common general knowledge
In the earlier decision the delegate considered this question. She concluded:
"I find that the combination of integers as set out in claim 1 is non-obvious over what has been declared to be common general knowledge. The dependent claims define further additions that provide for the efficiency gains of a process engineering system and are therefore also considered to be non-obvious."[29]
[29] [2012] APO 92 at [123].
I have no evidence before me that would lead to a different conclusion. The same conclusion logically applies to claim 25.
Ascertained
In the earlier decision, the ground of lack of inventive step was considered only in relation to the common general knowledge, and not in relation to any published documents:
"The opponent based its case on obviousness on section 7(2) only – common general knowledge alone."[30]
[30] [2012] APO 92 at [102].
However, I note that the delegate stated that the Engdahl patent would not have been ascertained (for the purposes of section 7(3)):
"Therefore the Engdahl patent does not pass the 7(3) hurdle which requires that the information be ascertained."[31]
[31] [2012] APO 92 at [105].
At the hearing I asked the parties whether they had any views as to why the delegate would have commented on a point that was not relevant to the decision. I was informed that the written submissions provided before the hearing indicated that the opponent would rely on the Engdahl patent as a citation, but that this was not pressed at the hearing. The delegate was presumably responding to a matter that was apparent from the totality of the information before her. I accept that this is a reasonable explanation.
The issue for me is what weight to give to the finding that Engdahl would not have been ascertained. The delegate came to her conclusion after finding that the Engdahl patent was not part of the common general knowledge,[32] and noting the following statement of Mr Dugan:
"it is my view that the patents set out in this section are not indicative of what I or I believe other persons in my field would have commonly referred to or would have known in Australia prior to 7 February 2003."[33]
[32] [2012] APO 92 at [103].
[33] [2012] APO 92 at [104].
This comment by Mr Dugan appears more directed to the issue of whether or not Engdahl is part of the common general knowledge. In relation to whether patents such as Engdahl would have been ascertained, there is other evidence available to me:
"I was aware of Engdahl before the priority date and I would have thought that Shell would also have been familiar, as I was, with worldwide art relevant to the international natural gas processing industry in which they were actively seeking patents."[34]
[34] Northrop at [4.3].
This shows that Dr Northrop was aware of the Engdahl patent, and further he seems to suggest that those working in the art have a wider awareness than that suggested by Mr Dugan. It is fair to say that Dr Northrop would have ascertained Engdahl, and I think it is a fair inference that others working in the art would also have ascertained Engdahl. It is unclear whether Dr Northrop would also have ascertained Valencia and Haut, but for the purposes of this decision I will treat them as within the type of documents that would reasonably have been ascertained.
Engdahl
The delegate found in the earlier decision that the process in the Engdahl patent did not involve a single process. In other words, the dehydration step was a separate process to the removal of the sour species. This was sufficient to dispose of the ground of novelty.
The declarants Valencia and Tsesmelis do not comment on the Engdahl patent, so they are of no assistance. Dr Northrop discusses the Engdahl patent, but he does not analyse the patent in detail. In the absence of comments from the declarants I have considered the Engdahl patent directly.
I will look first at whether it would have been a matter of routine to alter a process in which there are two processes (dehydration and sweetening) carried out back-to-back and instead carry out a single process in which two steps are carried out back-to-back. The distinction between the two arrangements is a fine point, and one that the declarants do not seem to address. I conclude that it is a distinction that is not appreciated by persons skilled in the art, and consequently it would be a matter of routine to use either arrangement.
Looking now at the nature of the step of removing the sour species, it is apparent that Engdahl discloses an arrangement in which the stream entering the vessel is cooled by expansion:
"The stream is expanded through valve 100 into the solids formation zone 101 where solids are formed in the presence of liquid. The formation zone provides contact surface area between liquid, vapour, and solids and provides cooling for the formation of these solids."[35]
[35] US 5,819,555 at col 5.
The numbered parts of the apparatus are shown in Figure 2 of the specification, reproduced here:
The language of the above quoted passage is capable of including the possibility that carbon dioxide solidifies after it enters the solids formation zone because (i) it has been cooled by expansion to the temperature at which it solidifies, or (ii) it is further cooled by the liquid to a temperature at which it solidifies. After the hearing I wrote to the parties to advise them that it seemed that the first interpretation was correct, but I allowed them further time to comment because this point was not raised at the hearing and was not addressed in the written submissions. The applicant responded stating that the temperature is unclear:
"Engdahl is unclear as to what the temperature of the feedstream is when the feedstream enters the solids formation zone. See also Dugan's first declaration in the previous opposition at paragraph 4.8, which states that the skilled person would consider that the separation process described in Engdahl would be unlikely to work."
The opponent stated that the temperature is unknown, but that the gas is cooled to a temperature at which solids form:
"Engdahl temperature of the feed stream on entering the solids formation zone is unknown but might be between -76°C and -95.56°C based on a review of Engdahl's Example … Expansion of the dried gas feed stream through the valve into the solids formation zone has the consequence of cooling the gas feed stream to the temperature at which CO2 solids form (assuming pressure is also conducive to CO2 solids formation)."
Taking account of these comments and the contents of the document, for the reasons that follow I am satisfied that the first interpretation is correct.
Firstly, the solids formation zone 101 commences at the expansion valve 100. While this does not suggest that solids form immediately upon exit from the expansion valve, it is a clear indication that once the gas has expanded to the pressure of the vessel solids can form. This is a clear disclosure that solids formation starts after expansion by the expansion valve, which must mean that the expanded gas is at a temperature at which solidification can occur.
Looking at the Example given in the specification, the carbon dioxide content of the feedstream is 5%, the separation vessel is at a pressure of 400 psia, and the feedstream enters the vessel at a temperature of -140 degrees F. By reference to Figure 1 in the specification, shown below, it is stated that the gas in the vessel will contain a maximum of about 1.1% carbon dioxide.[36]
[36] US 5,819,555 at col 7.
The remaining carbon dioxide solidifies, and falls to the bottom of the vessel along with a liquid hydrocarbon:
"Solid particles containing carbon dioxide and hydrocarbon liquids are collected in removal zone 105."[37]
[37] US 5,819,555 at col 7.
It seems clear that the gas (containing 5% carbon dioxide) is cooled to a temperature (-140 degrees F) at which carbon dioxide will solidify (so that a maximum of 1.1% remains in the gas). Solidification is in fact observed.
Consequently, all that is necessary is to apply the process in the Engdahl patent as it is described. No change is necessary. I believe it would be a matter of routine to operate the process exemplified in the Engdahl patent in the way in which it is described. I conclude that claim 1 lacks inventive step.
Turning to the appended claims, it is necessary to consider each claim in turn.
Claim 2: The dehydration is carried out by cooling to a temperature at which hydrates form (a first operating temperature). The Engdahl patent makes no reference to dehydration by formation of hydrates. The opponent's written submissions state that dehydration by formation of hydrates is one of the most common dehydration techniques. In this regard I note the evidence of Dr Valencia at [4.7]:
"It was well known as of February 2003 to cool a gas stream to induce the formation of hydrates and thereby reduce the water content of the gas stream."[38]
[38] Valencia at [4.7].
Dr Valencia gives further explanation of the process at [4.8]. I accept that formation of hydrates was a known process in 2003. The critical question is whether it would it have been a matter of routine to use this known process in the circumstances of the process described in the Engdahl patent? The evidence falls short of showing that this combination of features would have been arrived at as a matter of routine. I conclude that it has not been shown that claim 2 lacks inventive step.
Claim 3: Claim 3 is appended to claim 1 or claim 2. It specifies that expansion at the second vessel is achieved by a Joule-Thompson valve. A Joule-Thompson valve is explained by Mr Dugan in his declaration dated 8 May 2012:
"A J/T valve induces a pressure drop in the gas which in turn causes the gas to cool."
The valve 100 in the Engdahl patent is not stated to be a Joule-Thompson valve. However, it is stated that the "feedstream is expanded through valve 100 into solids formation zone 101".[39] It seems clear that valve 100 is a Joule-Thompson valve, so it would have been a matter of routine to use the valve as described. I conclude that claim 3, so far as it is appended to claim 1, lacks inventive step.
[39] US 5,819,555 at col 7.
Claim 4: Claim 4 is appended to claim 2 or 3. It specifies that the gas introduced into the dehydration vessel is cooled to below the first operating temperature. This necessarily introduces the feature of formation of hydrates, which I found was not a matter of routine. Thus it has not been shown the claim 4 lacks inventive step.
Claim 5: Claim 5 is appended to claims 1 to 3. It specifies that the gas entering the second vessel has been cooled to below the second operating temperature. It is uncertain whether the Engdahl patent discloses cooling to the second temperature, or to a temperature below this. There is no evidence it would be a matter of routine to do this. Thus it has not been shown that claim 5 lacks inventive step.
Claim 6: Claim 6 is appended to claim 2 or 3. It specifies that the gas introduced to the first vessel is at a temperature below the first operating temperature and the gas introduced to the second vessel is at a temperature below the second operating temperature. I have already found that it has not been shown that a temperature below the second operating temperature was a matter of routine. Thus it has not been shown that claim 6 lacks an inventive step.
Claim 7: Claim 7 is appended to claim 1. It specifies that a flash tank is used between the first vessel and the second vessel. Such an arrangement is not mentioned in the Engdahl patent. There is no evidence it would be a matter of routine to do this. Thus it has not been shown that claim 7 lacks inventive step.
Claims 8 to 11: These claims are dependent on claim 7, so it follows that the same conclusion applies to them.
Claim 12: Claim 12 is appended to claim 1. It specifies that a flash tank is used between the first vessel and the second vessel (with many other details). I have found that it has not been shown that the use of a flash tank was a matter of routine. Thus it has not been shown that claim 12 lacks inventive step.
Claim 13: Claim 13 is appended to claims 11 or 12, so it follows that the same conclusion applies to it.
Claim 14: Claim 14 is appended to claims 11 to 13, so it follows that the same conclusion applies to it.
Claim 15: Claim 15 is appended to claim 14, so it follows that the same conclusion applies to it.
Claim 16: Claim 16 is appended to claims 1 – 6. It specifies that a stream of liquid is introduced to the second vessel at a temperature below the second operating temperature. Such an arrangement is not demonstrated in the Engdahl patent. The opponent submitted that this is common in the CFZ process. However, this does not establish that it would have a matter of routine to incorporate it into the process in the Engdahl patent. Thus it has not been shown that claim 16 lacks inventive step.
100. Claim 17: Claim 17 is appended to claims 2 – 4. It specifies that a stream of liquid is introduced into both the first and second vessels. As noted in relation to claim 16, it has not been shown that this would be a matter of routine. Thus it has not been shown that claim 17 lacks inventive step.
101. Claims 18 and 19: Claims 18 and 19 are appended to claims 16 or 17, so it follows that the same conclusion applies to them.
102. Claim 20: Claim 20 is appended to claim 17 or 19, so it follows that the same conclusion applies to it.
103. Claim 21: Claim 21 is appended to claim 20, so it follows that the same conclusion applies to it.
104. Claim 22: Claim 22 is appended to claims 1 to 6 or 16 to 21. In so far as it is appended to claims 1 and 3, this claim needs to be further considered. It specifies that the sour species in the second vessel are heated to obtain a liquid containing sour species. The Engdahl patent discloses heating the liquid in the lower portion of the vessel to a temperature above the melting point of carbon dioxide:
"The temperature of the lower part of zone 105 is maintained at about -65 degrees F. which is warmer than the melting point of the carbon dioxide solids. Heat for maintaining the temperature is provided by one or more of heat exchanger 106."[40]
[40] US 5,819,555 at col 7 – 8.
105. I consider it would be a matter of routine to operate the vessel in the way described in the Example. I conclude that claim 22, so far as appended to claim 1 or 3, lacks inventive step.
106. Claim 23: Claim 23 is appended to claim 22. It specifies that the heating is achieved by adding the sour species to a warm liquid. In the Engdahl patent the liquid is warmed by the heat exchanger, so the solidified carbon dioxide falls into warm liquid. I consider that it would be a matter of routine to operate the vessel in the way described in the Example. I conclude that claim 23 lacks inventive step.
107. Claim 24: Claim 24 is appended to claim 23. It specifies that the liquid is natural gas liquid. The liquid in the Engdahl patent is natural gas liquid, since the process uses natural gas. I consider that it would be a matter of routine to operate the vessel in the way described in the Example. I conclude that claim 24 lacks inventive step.
108. Claim 25: Claim 25 is an omnibus claim. The features of claim 25 are quite specific, and include features that I have already found have not been shown to be a matter of routine. For instance, the dehydration step involves the formation of hydrates:
"In the embodiment of Figure 1, the water dew point of the gas exiting the first vessel 12, however, is lower than its equilibrium dew point due to the formation of hydrates."[41]
[41] AU 2012261477 at page 3.
109. In my discussion of claim 2 I stated that it has not been shown that it would have been a matter of routine to dehydrate by forming hydrates. It follows that it has not been shown that claim 25 lacks inventive step.
110. Claim 26: Claim 26 is appended to claims 2, 17 or 19 to 20. As none of these claims lack inventive step, it follows that the same conclusion applies to this claim.
111. Claim 27: Claim 27 is appended to claims 2, 17, 19 to 20 or 26. As none of these claims lack inventive step, it follows that the same conclusion applies to this claim.
112. Claim 28: Claim 28 is appended to claims 1 to 6, 16 to 24, 26 or 27. Insofar as it is appended to claims 1, 3, 22, 23 and 24 this claim needs to be further considered. It specifies that the gas removed from the second vessel is further treated by expansion and passage through heat exchangers. The Example does not mention processing steps after removal from the vessel. Dr Valencia stated that such an arrangement:
"reflects standard energy integration practiced by a competent engineer who wishes to reduce external costly heating and cooling utilities whenever there are process streams that can provide such heating and cooling. Such practice also reflects the common concern in natural gas plants, now and before the priority date, that cooling of a process stream not occur to an extent that hazard or poor operability would be caused by presence of solids."[42]
[42] Valencia at [6.18].
and
"Cooling of a stream such as the dehydrated gas stream from the first vessel is a usual heat exchange operation following the dehydration step"[43]
[43] Valencia at [6.19].
113. These statements show that such arrangements are not just known, but are normal in the art. It is a safe conclusion that what is normal in the art in relation to heat exchangers would be a matter of routine. I conclude that claim 28 lacks inventive step.
114. Claim 29: Claim 29 is appended to claim 28. It specifies that the gas removed from the second vessel, after being cooled by expansion, is passed to a heat exchanger to effect cooling of the gas removed from the first vessel. In the quote from Dr Valencia above it was noted that this is a "usual heat exchanger operation".[44] It follows that this specific heat exchanger arrangement is also a matter of routine, and claim 29 lacks inventive step.
[44] Valencia at [6.19].
115. Claim 30: Claim 30 is appended to claims 16 to 23, 26 or 27. Insofar as it is appended to claims 22 and 23 this claim needs to be further considered. It specifies that the gas removed from the second vessel is further treated by expansion and passage through heat exchangers. As noted, this feature is not a matter of routine. Thus it has not been shown that claim 30 lacks inventive step.
116. Claim 31: Claim 31 is appended to any of claims 1 to 30. Insofar as it is appended to claims 1, 22, 23, 24, 28 and 29 this claim needs to be further considered. The claim is directed to the gas produced by the process. There is no doubt it would have been a matter of routine to produce a dehydrated and sweetened gas by operating the process of the Engdahl patent. I conclude that claim 31 lacks inventive step.
117. Claims 1, 3, 22, 23, 24, 28, 29, 31 lack inventive step in light of the Engdahl patent.
Valencia
118. The delegate found in the earlier decision that the Valencia patent did not involve a single process. In other words, the dehydration step was a separate process to the removal of the sour species.[45] The delegate further found that the cooling in the second vessel was by means of contact with liquid spray:
[45] [2012] APO 92 at [82].
"Furthermore, the process of D1 relies on solid formation through contact of vapour with liquid spray from nozzles (D1, col. 6, lines 18 – 20). This feature is different to opposed claim 1, where cooling of the gas is by means of expansion to a second operating temperature at which solids of the sour species are formed."[46]
[46] [2012] APO 92 at [83].
119. The absence of both a single process and cooling by means of expansion alone was sufficient for the delegate to dispose of the ground of lack of novelty.[47] As I discussed above in relation to the Engdahl patent, it would be a matter of routine to adopt a single process. However, it is not clear that it would have been a matter of routine to alter the manner of solidification of the carbon dioxide.
[47] [2012] APO 92 at [88].
120. The delegate made some useful observations in the earlier decision. The delegate considered there was not a lack of inventive step in the light of what was known in the common general knowledge about the CFZ process. The delegate stated:
"Starting from this process would the person skilled in the art be directly led as a matter of course to eliminate the distillation zone that produces the freezing zone vapour feed and convert the process to one where simple expansion would provide for freezing of the sour species? Would the person skilled in the art then add a first vessel into the process to dehydrate the gas?"[48]
[48] [2012] APO 92 at [113].
121. The delegate focussed on the second question:
"As there is no evidence provided by the opponent to support that the person skilled in the art would modify the CFZ™ process to arrive at the two vessel process of the current application, the CFZ™ process does not render claim 1 obvious."[49]
[49] [2012] APO 92 at [114].
122. It is clear that the delegate made no finding of fact in relation to the first question of whether it would have been a matter of routine to alter the means for solidifying the carbon dioxide. Consequently the earlier decision is of no assistance on this point and it is open to me to consider any evidence that is before me.
123. The evidence of Dugan and Northop seems to dwell on whether it would have been counter-intuitive to use a process that involved formation of solids. As Northrop notes, the Engdahl patent itself discloses the formation of carbon dioxide solids.[50] I can find no evidence that suggests that any of the declarants considered the question of whether it would have been a matter of routine to alter the CFZ vessel to make it operate in a different way. I think this is understandable. The CFZ vessel is a complex piece of equipment that had been found to be able to achieve impressive results. It seems to me that it would truly be counter-intuitive to contemplate modifying the vessel so that it could no longer achieve these advantages. Thus the declarants do not even consider the question.
[50] Northrop at [3.14].
124. I am satisfied that the opponent has not shown that it would be a matter of routine to modify the CFZ vessel in the Valencia patent so that the inlet stream is cooled by expansion to a temperature at which the carbon dioxide solidifies. It has not been shown that any claims lack inventive step in light of the Valencia patent.
Haut
125. The Haut document was not considered by the delegate in the earlier decision. As a consequence I will consider it for myself.
126. The content of Haut can be understood by considering the Summary provided at the start of the document:
"The controlled-freeze-zone (CFZ) process is a cryogenic distillation technique for separating CO2 and heavier compounds from methane (C1). This paper describes how the process controls the freezing and melting of CO2 in a specifically designed section of an otherwise conventional tower. In addition to describing the process, this paper compares the CFZ process to other gas-treating processes, discusses pilot-plant operational results, and gives examples of potential CFZ applications. The CFZ process is a simple, cost-effective method to process gas streams containing CO2 using proven facilities, equipment and control philosophies and has been demonstrated through the operation of a large-scale pilot plant."[51]
[51] Haut at p 265.
127. In relation to the critical question of whether the stream that enters the vessel is at a temperature at which solids of the sour species are formed, the document is clear on its face:
"Operation of a CFZ column would occur in the vapor/solid and vapor/liquid regions. Vapor in the lower section of the column becomes leaner in CO2 and colder while rising through the liquid of each stage. The vapor eventually reaches a phase region where, upon further cooling, a liquid mixture of C1 and CO2 cannot exist. Rather, a solid, pure CO2 phase will form in equilibrium with a C1/CO2 vapor. Further cooling will continue to form pure, solid CO2 from the vapor."[52]
[52] Haut at p 265.
128. Consequently, the key question is the same as in relation to the other citations: would it have been a matter of routine to alter the operation of the CFZ vessel. As stated above, the answer is NO. It has not been shown that any claims lack inventive step in light of the Haut document.
Conclusion on inventive step
129. Claims 1, 3, 22, 23, 24, 28, 29, 31 lack inventive step in light of the Engdahl patent.
Fair basis
130. It is a requirement of subsection 40(3) of the Act that the claims must be fairly based on the matter described in the specification:
The claim or claims must be clear and succinct and fairly based on the matter described in the specification.
131. The High Court in Lockwood Security Products Pty Ltd v Doric Products Pty Ltd[53] approved the words of Gummow J in Rehm Pty Ltd v Websters Security Systems (International) Pty Ltd:[54]
[53] [2004] HCA 58 at [69]; 217 CLR 274 at 300.
[54] (1988) 81 ALR 79 at 95.
"the question is whether there is a real and reasonably clear disclosure in the body of the specification of what is then claimed, so that the alleged invention as claimed is broadly, that is to say in a general sense, described in the body of the specification"
132. The opponent submitted that the claims 1, 3-24 and 26-31 are not fairly based as they do not contain a requirement that the dehydration is conducted by formation of hydrates. The reason why formation of hydrates is an essential feature is as follows:
- the formation of hydrates was found to be an essential feature of the parent application
- the present application differs from the parent application in that some of the references to hydrate formation have been removed
- the present specification still discusses hydrate formation as part of the prior art, but recognising that formation of hydrates is usually prevented
- the present specification discloses prior art dehydration by absorption or adsorption and notes that these processes are complex and expensive
- it would be inconsistent to view the invention as including things that were the problem with the prior art (i.e. dehydration by adsorption or absorption)
133. The specification no longer contains the following statement that concerned the delegate in the earlier decision:
"An essential feature of the process of the present invention is that on purpose hydrates are formed in order to remove water."[55]
[55] [2012] APO 92 at [35].
134. Instead, the text now makes it clear that hydrate formation is only one aspect of the invention. For instance:
"In the embodiment of Figure 1, the first operating temperature and the pressure in the first vessel 12 are maintained at a level whereby hydrates are formed (again it should be noted that according to the present invention, dehydration of teh (sic) feed stream is not limited to hydrate formation)."[56]
[56] AU 2012261477 at page 4.
135. I consider that the specification that I am considering contains a real and reasonably clear disclosure of a process that includes dehydration by formation of hydrates or otherwise. The fact some of these dehydration processes are complex and expensive does not alter the fact that an overall process of dehydration and sweetening including such processes is disclosed. It has not been shown that there is a lack of fair basis.
Conclusion
136. Claims 1, 3, 22, 23, 24, 28, 29, 31 lack inventive step in light of the Engdahl patent.
137. This deficiency can be overcome by amendment. Consequently I allow the applicant two months to propose amendment to overcome this ground of opposition. These amendments should take account of the fact that the application will not be able to proceed to grant if any of the claims are identical to claims of the parent application.[57]
[57] Section 64(2).
Costs
138. The parties submitted that costs should follow the event. I have found that the opposition succeeds on the ground of lack of inventive step. I see no reason that costs should not follow that outcome. Costs will be awarded against the applicant.
Dr S.D. Barker
Delegate of the Commissioner of PatentsANNEX Claims of the patent application
1. A process for removing contaminants from a natural gas feed stream including water and sour species, which process comprises the steps of dehydrating the natural gas feed stream in a first vessel; removing from the first vessel a stream of dehydrated gas; cooling by means of expansion the dehydrated gas in a second vessel to a second operating temperature at which solids of the sour species are formed; and removing from the second vessel a stream of dehydrated sweetened gas.
2. The process according to claim 1, wherein dehydrating the natural gas feed stream includes cooling the natural gas feed stream to a first operating temperature at which hydrates are formed.
3. The process according to claim 1 or claim 2, wherein the means of expansion is a Joule-Thompson valve.
4. The process according to claim 2 or claim 3, wherein the step of cooling the natural gas feed stream in a first vessel to a first operating temperature comprises introducing the natural gas feed stream into the first vessel at a temperature that is 15 below the first operating temperature.
5. The process according to any one of claims 1 to 3, wherein the step of cooling the dehydrated gas in a second vessel to a second operating temperature comprises introducing the dehydrated gas into the second vessel at a temperature that is below the second operating temperature.
6. The process according to claim 2 or claim 3, wherein the step of cooling the natural gas feed stream in a first vessel to a first operating temperature comprises introducing the natural gas feed stream into the first vessel at a temperature that is below the first operating temperature, and wherein the step of cooling the dehydrated gas in a second vessel to a second operating temperature comprises introducing the dehydrated gas into the second vessel at a temperature that is below the second operating temperature.
7. The process according to claim 1, comprising: cooling the stream of dehydrated gas removed from the first vessel to form a two-phase mixture of dehydrated gas and condensate, passing the two-phase mixture of dehydrated gas and condensate into a flash tank, separating the condensate from the dehydrated gas in the flash tank, removing the dehydrated gas from which the condensate has been separated from the flash tank, and introducing the dehydrated gas from which the condensate has been separated into the second vessel.
8. The process according to claim 7, wherein the stream of dehydrated gas removed from the first vessel is cooled in a heat exchanger to form the two-phase mixture of dehydrated gas and condensate.
9. The process according to claim 7 or claim 8, wherein the stream of dehydrated gas removed from the first vessel is cooled to form the two-phase mixture of dehydrated gas and condensate at a temperature higher than -56°C.
10. The process according to any one of claims 7 to 9, further comprising:
removing a liquid stream of condensate from the flash tank.11. The process according to claim 10, further comprising: introducing at least part of the liquid stream of the condensate into the second vessel.
12. The process according to claim 1, comprising: cooling the stream of dehydrated gas removed from the first vessel to form a two-phase mixture of dehydrated gas and condensate, passing the two-phase mixture of dehydrated gas and condensate into a flash tank, separating the condensate from the dehydrated gas in the flash tank, removing a liquid stream of condensate from the flash tank, removing the dehydrated gas from which the condensate has been separated from the flash tank, and introducing the dehydrated gas from which the condensate has been separated into the second vessel, wherein the step of cooling the dehydrated gas from which the condensate has been separated in the second vessel to the second operating temperature further comprises introducing at least part of the liquid stream of the condensate removed from the flash tank into the second vessel at a temperature that is below the second operating temperature to form a slurry or mixture with the sour species.
13. The process according to claim ll or 12, wherein the concentration of C2 - C4 hydrocarbon components in the at least part of the stream of condensate removed from the flash tank and introduced into the second vessel is from about 0.5 to 1.5 per mol of C02 in the natural gas feed stream.
14. The process according to any one of claims 11 to 13, wherein the at least part of the stream of condensate removed from the flash tank is introduced into the second vessel through an inlet located above an inlet introducing the dehydrated gas from which the condensate has been separated.
15. The process according to claim 14, wherein the inlet introducing the at least part of the stream of condensate removed from the flash tank into the second vessel is a plurality of spray nozzles.
16. The process according to any one of claims 1-6, wherein the step of cooling the dehydrated gas in a second vessel to a second operating temperature further comprises introducing the dehydrated gas into the second vessel and introducing a stream of liquid into the second vessel at a temperature that is below the second operating temperature to form a slurry or mixture with the sour species.
17. The process according to any one of claims 2 to 4, wherein the step of cooling the natural gas feed stream in a first vessel to a first operating temperature comprises introducing the natural gas feed stream into the first vessel and introducing a stream of liquid into the first vessel at a temperature that is below the first operating temperature to form a slurry with the hydrates, and wherein the step of cooling the dehydrated gas in a second vessel to a second operating temperature further comprises introducing the dehydrated gas into the second vessel and introducing a stream of liquid into the second vessel at a temperature that is below the second operating temperature to form a slurry or mixture with the sour species.
18. The process according to claim 16 or claim 17, wherein the stream of liquid is a natural gas liquid.
19. The process according to claim 16 or 17, wherein the concentration of C2 - C4 hydrocarbon components in the stream of liquid introduced into the second vessel is from about 0.5 to 1.5 per mol of C02 in the natural gas feed stream 20. The process accordi11g to claim 17 or claim 19, wherein the stream of liquid is introduced into the second vessel through an inlet located above an inlet introducing the dehydrated gas.
21. The process according to claim 20, wherein the inlet introducing the stream of liquid into the second vessel is a plurality of spray nozzles.
22. The process according to any one of claims 1 to 6 or 16 to 21, further comprising the step of heating the sour species in the second vessel to a temperature that is above the second operating temperature to obtain a sour species-containing liquid.
23.The process according to claim 22, wherein heating the sour species in the second vessel comprises adding to the sour species a warm liquid.
24. The process according to claim 23, wherein the warm liquid is a natural gas liquid.
25. A process for removing contaminants from a natural gas feed stream including water and sour species comprising the steps, substantially as hereinbefore described with reference to the examples and figures 1 and 2.
26. The process according to any one of claims 2, 17 or 19 to 20, wherein the stream of dehydrated sweetened gas removed from the second vessel is at a temperature of not less than -85°C.
27. The process according to any one of claims 2, 17, 19 to 20 or 26, wherein the stream of dehydrated sweetened gas removed from the second vessel is at a pressure of between 20 and 50 bar.
28. The process according to any one of claims 1 to 6, 16 to 24, 26 or 27, wherein the stream of dehydrated sweetened gas removed from the second vessel is further cooled by means of expansion and passed to one or more heat exchangers to effect cooling of one or more other process streams, but the temperature to which the stream of dehydrated gas removed from the first vessel is cooled in any such heat exchanger is greater than the temperature at which solids of the sour species are formed.
29. The process according to claim 28, wherein the stream of dehydrated sweetened gas removed from the second vessel and further cooled by means of expansion is passed to a heat exchanger to effect cooling of the stream of dehydrated gas removed from the first vessel.
30. The process according to any one of claims 16 to 23, 26 or 27, wherein the stream of dehydrated sweetened gas removed from the second vessel is further cooled by means of expansion and passed to a first heat exchanger to effect cooling of the stream of liquid to be introduced into the second vessel, the stream of dehydrated sweetened gas is then passed to a second heat exchanger to effect cooling of the stream of dehydrated gas removed from the first vessel, but the temperature to which the stream of dehydrated gas removed from the first vessel is cooled in the second heat exchanger is greater than the temperature at which solids of the sour species are formed.
31. The dehydrated sweetened gas of the process of any one of claims 1 to 30.
1
14
0