METHODS FOR SPLITTING MIXED HYDROCARBON STREAMS

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/081,687, entitled “Methods For Splitting Mixed Hydrocarbon Streams,” filed on Nov. 19, 2014, which is incorporated herein by reference in its entirety as if fully set forth below.

FIELD OF THE INVENTION

This invention relates to mixed hydrocarbon streams, particularly liquid gasoline streams extracted from natural gasoline wells, and to methods of splitting those streams into defined product streams, including an overhead pentane stream with defined ratios of n-pentane to isopentane, and a bottoms stream comprising heavier hydrocarbons.

BACKGROUND OF THE INVENTION

Hydraulic finking has tapped into enormous volumes of energy reserves in North America, but it has also resulted in the production of large volumes of NGLs and lesser value streams that have limited industrial utility and market applications. The production of liquid gasoline, for example, has increased dramatically as natural gas is extracted from hydraulic fracking wells.

Liquid extracted from natural gas deposits (natural gas liquids or NGLs) typically consists of several hydrocarbon components of differing value and industrial utility. Common NGL products are ethane (C₂H₆), propane (C₃H₈), butanes (iC₄H₁₀ and nC₄H₁₀) and natural gasoline (C₅₊). Natural gasoline, sometimes known as condensate or naphtha, refers to the pentanes and heavier components in a natural gas stream, and usually is primarily made up of straight and branched chain paraffins. Natural gasoline is most commonly used as refinery feedstock, although it can also be used as a petrochemical feedstock.

One potential use for NGLs is as a hydrocarbon feedstock for the production of refinery-grade gasoline, and numerous publications have proposed using the components of NGLs in this manner. For example, several publications, including U.S. Pat. Nos. 6,679,302, 7,631,671 and 8,192,510 to Mattingly and Vanderbur, have described the use of butane to expand refinery grade gasoline downstream of the refinery. Butane is especially useful in these blending operations because of its consistent physical contribution to volatility and octane in a blended gasoline pool.

U.S. Pat. Nos. 7,456,328 and 7,741,525 teach methods for blending propane into an ethane containing stream to increase the vapor pressure of the ethane, thereby allowing for production of an “on-spec” propane product stream while at the same time maximizing the value of the ethane stream.

The mixed pentanes derived from NGL and natural gasoline streams have found less market applications and industrial utility than their lighter counterparts due in large part to the variability in pentane's hydrocarbon content, and uncertainty about how much impact this inconsistency will have on the volatility and octane of a hydrocarbon stream with which the pentanes are mixed. This is especially true for pentane streams that contain large amounts of n-pentane, which has a neat octane value of only 65, and whose effect on fuel octane is variable and uncertain. The following table summarizes relevant physical properties associated with pentane when blended into gasoline:

				Neat	Blending
	Boiling			Octane	Octane
	Pt		TV/L =	(R +	(R +
	(° F.)	RVP	20	M/2)	M/2)

n-butane	31	55	negative	92	92
n-pentane	97	16	87	65	>65
neopentane	49	20	50	83	>83
isopentane	82	35	1	91	91

As can be seen, the addition of n-pentane to a gasoline stream, or the addition of mixed pentanes that include n-pentane, could be expected to significantly and negatively impact the octane value of the gasoline stream, given the low blending octane value of n-pentane.

SUMMARY OF THE INVENTION

Methods for splitting low-value natural gasoline streams have now been developed that produce pentane streams with defined n-pentane and isopentane ratios. As long as the ratio of n-pentane to isopentane is controlled in the splitting operation, these pentane streams, which have previously been considered low value by-products of natural gasoline, can be added to refined gasoline without negatively impacting the octane value of the gasoline, thereby greatly increasing the value of the pentanes. It has been experimentally found that these mixed pentanes can be added to gasoline in proportions as high as 15 or even 20% (i.e. 15 or 20 parts pentanes to 85 or 80 parts gasoline).

The methods partly depend on the discovery that isopentane can effectively offset the low blending octane value of n-pentane when defined isopentane:n-pentane ratios are observed in the production of the mixed pentane stream. The methods also depend on the discovery that the natural gasoline streams from fracking operations lend themselves to these operations, such that mixed pentanes meeting defined isopentane:n-pentane ratios can be split from the natural gasoline using a suitably designed depentanizer.

Therefore, in a first embodiment the invention provides a method of making mixed pentanes comprising: (a) providing a natural gasoline stream comprising: (i) 0 wt % methane or ethane or propane; (ii) from 0 to 5.0 wt % butane; (iii) from 5 to 80 wt % isopentane; (iv) from 5 to 80 wt % normal pentane; and (v) from 10 to 90 wt % of hydrocarbons consisting of 6 or more carbon atoms (C₆₊ hydrocarbons); (b) splitting said natural gasoline stream into a bottom stream and an enriched overhead pentane stream comprising: (i) greater than 95 wt % of said butane in said natural gasoline stream; (ii) greater than 95 wt % of said isopentane in said natural gasoline stream; (iii) greater than 95 wt % of said normal pentane in said natural gasoline stream; and (iv) from 0 to 20 wt % of said C₆₊ hydrocarbons in said natural gasoline stream; and (c) recovering said enriched overhead pentane stream.

As shown in FIG. 1, these methods are preferably performed in a suitably designed depentanizer distillation column in which the higher volatility pentanes are withdrawn from the top of the tower and the lower volatility heavier hydrocarbons are withdrawn from the bottom of the tower. In a particularly preferred embodiment, the mixed pentanes produced by the methods of the present invention are suitable for mixing into a refined gasoline stream meeting applicable ASTM specifications.

A second principal embodiment relates to the enriched pentane produced by the methods of the present invention. Thus, in another embodiment the invention provides an enriched pentane stream suitable for mixing into a refined gasoline stream meeting ASTM D4814-13b made by the process of the first principal embodiment or any subembodiment thereof.

In yet another principal embodiment the invention provides an enriched pentane stream suitable for mixing into a refined gasoline stream meeting ASTM D4814-13b comprising: a) 0 wt % methane or ethane or propane; b) from 0.01 to 5 wt % butane; c) from 30 to 70 wt % isopentane; d) from 30 to 70 wt % normal pentane; and e) from (0.01 to 5 wt % hydrocarbons having 6 or more carbons.

Additional advantages of the invention are set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.

DESCRIPTION OF THE FIGURES

FIG. 1 depicts a representative system of the present invention for splitting a natural gasoline stream into a mixed pentane stream that contains isopentane and n-pentane at designated ratios.

DETAILED DESCRIPTION

Definitions and Use of Terms

“ASTM” refers to the American Society for Testing and Materials. Unless otherwise indicated, when reference is made to an ASTM standard herein, it is made in reference to the ASTM standard in effect on Oct. 1, 2012, and the ASTM standard is incorporated herein by reference.

“Butane” refers to isobutane and n-butane and mixtures thereof, but preferably refers to n-butane.

“Certified gasoline” is fuel meeting the standards of ASTM Standard Specification Number D 4814-01a (“ASTM 4814”), and should be distinguished from in-process gasoline streams at a refinery that have not been released from the refinery and have not been certified. The specifications for different types of gasoline set forth in ASTM 4814 vary based on a number of parameters affecting volatility and combustion such as weather, season, geographic location and altitude. For this reason, gasoline types produced in accordance with ASTM 4814 are broken down into volatility categories AA, A, B, C, D and E, and vapor lock protection categories 1, 2, 3, 4, 5, and 6, each category having a set of specifications. Certified gasoline also includes a gasoline certified to meet ASTM 4814 upon the addition of a designated quantity of ethanol.

“Hydrocarbon” refers to any linear, branched, or cyclic molecule, aliphatic or aromatic, saturated or unsaturated, composed primarily of hydrogen and carbon.

The enriched pentane stream of the present invention will comprise “mixed pentanes,” referring to a stream or pool of pentanes that contains n-pentane in addition to isopentane. The stream or pool might also contain neopentane, although this compound is quite rare in natural supplies. The pentanes preferably make up at least 10%, 30%, 50%, 70%, 90% or 95% of the enriched pentane stream. The pentanes can be present in an ratio that satisfies the performance requirements of this invention, but preferably contain front 20% of 30% up to 100% isopentane, with the balance being n-pentane. In any of the various embodiments and subembodiments discussed herein, the mixed pentanes can be characterized by a minimum ratio of isopentane to n-pentane of 1:5, 2:5, 3:5, 4:5, 5:5, 10:5, or greater, an isopentane to n-pentane ratio of from 30:70 to 95:5, from 30:70 to 60:40, or an isopentane to n-pentane ratio of from 40:60 to 50:50.

Ratios, quantities and rates of liquid flows expressed herein, unless otherwise specified, are expressed in terms of volume, and are preferably measured at room temperature (25° C.) and atmospheric pressure.

When the singular forms “a,” “an” and “the” or like terms are used herein, they will be understood to include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a hydrocarbon” includes mixtures of two or more such hydrocarbons, and the like. The word “or” or like terms as used herein means any one member of a particular list and also includes any combination of members of that list.

Throughout the description and claims of this specification, the word “comprise” and variations of the word, such as “comprising” and “comprises,” means “including but not limited to,” and is not intended to exclude, for example, other additives, components, integers or steps.

When ranges are given by specifying the lower end of a range separately from the upper end of the range, it will be understood that the range can be defined by selectively combining any one of the lower end variables with any one (If the upper end variables that is mathematically possible.

The invention is defined in terms of three principal embodiments. When an embodiment or subembodiment other than the principal embodiment is discussed herein, it will be understood that the embodiment or subembodiment can be applied to farther limit any three of the principal embodiments.

Discussion

As mentioned above, the invention is based on the discovery that isopentane overcomes the negative effects of n-pentane on blend octane values when the two pentanes are present in defined ratios, the discovery that natural gasoline streams coming onto the market are suitable for producing such mixed pentanes, and the development of processes for splitting mixed pentanes from the natural gasoline stream to ensure that the mixed pentanes withdrawn from the top of the depentanizer properly balance the ratio of isopentane and n-pentane.

In a first principal embodiment the invention provides a method of making pentanes suitable for mixing into a refined gasoline stream meeting applicable ASTM specifications comprising: a) providing a natural gasoline stream comprising: i) 0 wt % methane or ethane or propane; ii) from 0, 0.01, or 0.1 wt % to 5.0, 1.5, or 0.5 wt % butane; iii) from 5, 10 or 15 to 80, 50 or 35 wt % isopentane; iv) from 5, 10 or 15 to 80, 50 or 35 wt % normal pentane; and v) from 10, 20 or 30 to 90, 80 or 70 wt % hydrocarbons consisting of 6 or more carbon atoms (C₆₊ hydrocarbons); b) splitting said natural gasoline stream into a bottom stream and an enriched overhead pentane stream comprising: i) greater than 95, 98, or 99.5 wt % of said butane in said natural gasoline stream; ii) greater than 95, 97, or 9 wt % of said isopentane in said natural gasoline stream; iii) greater than 95, 97 or 98 wt % of said normal pentane in said natural gasoline stream; and iv) from 0, 0.01, or 0.1 wt % to 20, 5, or 2 wt % of said C₆₊ hydrocarbons in said natural gasoline stream; and c) recovering said enriched overhead pentane stream.

The methods of the present invention can be performed according to traditional distillation techniques described in the prior art including Henry Z. Kister, Chemical engineering: Distillation design McGraw-Hill 1992 (1^st Edition). In a preferred embodiment the method comprises splitting said natural gasoline stream into an enriched overhead pentane stream in a distillation column comprising from 15 to 70 trays having a tray efficiency of greater than 80%. Particular methods for performing the methods are described in the examples and FIG. 1 hereto.

In a particular subembodiment of the methods of this invention, (a) the natural gasoline stream comprises (i) from 0.01 to 1.5 wt % butane; from 10 to 50 wt % isopentane; (iii) from 10 to 50 wt % normal pentane; and (iv) from 20 to 80 wt % C₆₊ hydrocarbons; (b) said enriched overhead pentane flow comprises (i) greater than 98 wt % of said butane in said natural gasoline stream; (greater than 97 wt % of said isopentane in said natural gasoline stream; (iii) greater than 97 wt % of said normal pentane in said natural gasoline stream; and (iv) from 0.1 to 5 wt % of said C₆₊ hydrocarbons in said natural gasoline stream.

In another particular subembodiment of the methods of the invention: (a) said natural gasoline comprises (i) from 0 to 0.5 wt % butane, (ii) from 15 to 35 wt % isopentane: (iii) from 15 to 35 wt % normal pentane; and (iv) from 30 to 70 wt % C₆₊ hydrocarbons; and (b) said enriched isopentane flow comprises (i) greater than 99.5 wt % of said butane in said natural gasoline stream; (ii) greater than 98 wt % of said isopentane in said natural gasoline stream; (iii) greater than 98 wt % of said normal pentane in said natural gasoline stream; and (iii) from 0.01 to 2 wt of said C₆₊ hydrocarbons in said natural gasoline stream.

Another subembodiment depends on the control of olefinic and aromatic compounds in the input stream, and in this subembodiment the natural gasoline stream comprises less than 5 or 2 wt % of olefinic and aromatic compounds.

Yet another subembodiment relates to the use of the method to control sulfur compounds in the final product. In this subembodiment, (a) said liquid gasoline stream comprises from 5, 10 or 15 to 50, 40 or 30 ppm sulfur compounds; (b) said enriched overhead pentane stream comprises less than 60, 40, or 20 of said sulfur compounds in said liquid gasoline stream; and (c) said enriched overhead pentane stream comprises greater than 1 or 2 and less than 30 or 10 ppm sulfur compounds. Exemplary sulfur containing compounds include hydrogen sulfide (H₂S), carbonyl sulfide (COS), methyl mercaptan (MeSH), ethyl mercaptan (EtSH), carbon disulfide (CS₂), isopropyl mercaptan (iC3SH), and isobutyl mercaptan (iC₄SH).

In another subembodiment, (a) said liquid gasoline stream comprises from 10 to 30 ppm sulfur compounds; and (h) said enriched pentane stream comprises greater than 1 and less than 10 ppm sulfur compounds. In still another subembodiment a) said liquid gasoline stream comprises from 15 to 40 ppm sulfur containing compounds; and (c) said enriched pentane stream comprises greater than 1 and less than 10 ppm sulfur compounds. In either embodiment, the enriched overhead pentane stream preferably comprises less than 40, 50 or 60% of the sulfur compounds in the natural gasoline stream.

Another principal embodiment relates to the pentane stream produced by any of the foregoing embodiments. Therefore, the invention also provides an enriched pentane stream suitable for mixing into a refined gasoline stream meeting ASTM D4814-13b made by the process of any of the foregoing embodiments or subembodiments.

Another principal embodiment relates to the novelty of the pentane stream produced the foregoing embodiments. In this embodiment the invention provides an enriched pentane stream suitable for mixing into a refined gasoline stream meeting ASTM D4814-13b comprising: a) 0 wt % methane or ethane or propane; b) from 0.01 to 5 wt % butane; c) from 30 to 70 wt % isopentane; d) from 30 to 70 wt % normal pentane; and e) from 0.01 to 5 wt % hydrocarbons having 6 or more carbons. In one subembodiment the enriched pentane stream comprises greater than 1 or 2 ppm and less than 10 or 30 ppm sulfur containing compounds. In another subembodiment the enriched pentane stream comprises greater than 1 ppm and less than 10 ppm sulfur containing compounds.

EXAMPLES

The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how the methods claimed herein are made and evaluated, and are intended to be purely exemplary of the invention and are not intended to limit the scope of what the inventor regards as his invention. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.) but some errors and deviations should be accounted for.

Example 1

Case Study of Depentanizer Tower Performance at Various Conditions

A simulation study was undertaken to evaluate the impact of various operating parameters on the performance of a depentanizing tower, and the ability of the depentanizing tower to produce mixed pentanes meeting the specifications described in the instant specification. The results are presented in Tables 1.a and 1.b.

TABLE 1.a
Case Study of Sunoco Tower Depentanizer Performance at Various Conditions

									Case 8
									(Note 3)
									Soluble
		Case 1						Case 7	H2O,
		Original	Case 2	Case 3	Case 4	Case 5		(Note 2)	2 vol %
		0.2 vol %	0.1 vol %	Soluble	Soluble	Soluble	Case 6	Soluble	Butane
		H2O,	H2O,	H2O,	H2O,	H2O,	Soluble	H2O,	(Increase
		2 vol %	2 vol %	2 vol %	1 vol %	0.5 vol %	H2O, 0%	2 vol %	reboiler
Title		Butane	Butane	Butane	Butane	Butane	Butane	Butane	duty)
Property	Units	Value	Value	New Base	Value	Value	Value	Value	Value

TOWER
PERFORMANCE
C5 Recovery	vol %	97.0%	97.0%	97.0%	97.0%	97.0%	97.0%	97.0%	99.7%
C5 Purity	vol %	96.0%	96.0%	96.0%	96.0%	96.0%	96.0%	96.0%	96.0%
Free water from	lb/hr	577	278	22	22	22	22	22	22
Overhead Drum
Feed/Btms Exchanger	MM Btu/hr	5.16	5.16	5.16	5.16	5.16	5.16	5.16	5.16
Duty
Reboiler Duty	MM Btu/hr	45.2	45.2	45.2	36.7	35.5	34.6	48.4	60
FEED
Temp of Feed	Deg F.	100	100	100	100	100	100	60	100
RVP of Feed	psia	13.6	13.6	13.6	13.1	12.9	12.6	12.6	13.6
TVP of Feed	psia	14.1	14.1	14.1	13.6	13.3	13.0	6.2	14.1
TVP of Feed @ 60 F.
Water in Feed	vol %	0.200%	0.102%	0.015%	0.015%	0.015%	0.015%	0.015%	0.015%
Free water in Feed	lb/hr	555	256	0	0	0	0	0
Total water in Feed	lb/hr	600	300	44	44	44	45	44	44
nC4 in Feed	vol %	2.0%	1.0%	2.0%	1.0%	0.5%	0.0%	2.0%	2.0%
C5 PRODUCT
Temp of C5 Product	Deg F.	100	100	100	100	100	100	100	100
nC4 in C5 Product	vol %	3.53	3.53	3.53	1.77	0.88	0.00	3.53	3.44
RVP of C5 Product	paia	19.4	19.4	19.4	18.6	18.2	17.9	19.4	19.1
TVP of C5 Product	psia	20.3	20.3	20.3	19.4	18.9	18.4	20.3	20.2
Cases 3 through 5
have only soluble
water in the feed.
TVP of C5 Product as
a function of
temperature for the
case of 2 lv % nC4 in
the feed (Note 1).
Temperature	Deg F.	90	100	120	130
Pressure	psia	16.8	20.3	31.3	33.9
Note 1:
The RVP of the CS product is not a function of temperature since it represents the vapor pressure at a given temperature of 100 F.
Note 2:
Temperature of Feed = 100 F. except for Case 7 where it is 60 F.
Note 3:
Reboiler duty for Case 8 is set at 60 MM Btu/hr which improves the % recovery of the C5s.

TABLE 1.b
Case 1	Case 2	Case 3	Case 4	Case 5	Case 6

577	278	22	22	22	22	Water from
						Ovhd Drum
45,564,222	45,409,652	45,186,302	36,676,087	35,527,629	34,626,371	Reboiler Duty
13.6	13.6	13.6	13.1	12.9	12.6	RVP of Feed
14.1	14.1	14.1	13.6	13.3	13.0	TVP of Feed
600.0	300.3	44.3	44.7	44.9	45.1	Water in Feed
0.0020439	0.001023	0.000151105	0.000152455	0.000153138	1.54E−04	vol frac water
						in feed
100	100	100	100	100	1.00E+02	Temp of C5
						Product
19.4	19.4	19.4	18.6	18.2	17.9	RVP of C5
						Product
20.1	20.3	20.3	19.4	18.9	18.4	TVP of C5
						Product
0.0353	0.0353	0.0353	0.0177	0.0088	0.0000	vol fr nC4 in C5
						Product
0.020	0.020	0.0199	0.009948431	0.004974212	0.00E+00	vol frac nC4 in
						Feed

Example 2

Simulation of Depentanizer and Associated Streams Under Optimized Conditions

The pentane splitting operation depicted in FIG. 1 was simulated using a set of assumed operating conditions to determine the overall properties of the process streams, including the natural gasoline input to the depentanizer, the mixed pentane stream withdrawn from the top of the depentanizer, and the heavy hydrocarbon stream withdrawn from the bottom of the depentanizer. The properties and content of the various streams depicted in FIG. 1 are given in Tables 2.a and 2.b.

TABLE 2.a
Properties of Streams 1-9

	1	2	3	4		6	7
Stream Number	Natural	Preheated	Tower	Tower	5	PURITY	Liquid	8	9
	Gasoline to	Natural	Overhead	Overhead	Tower	C5s to	to	Reboiler	Tower
Stream Description	Fractionator	Gasoline	Vapor	Liquid	Reflux	Storage	Reboiler	Boilup	Bottoms

Overall Properties
Pressure, psig	200	45	30	30	30	30	40	40	40
Temperature, ° F.	97	162	155	100	105	105	241	254	254
Std. Vol Flow (V),	—	—	32.6	—	—	—	—	34.3	—
MMSCFD
Std. Vol Flow (L),	19,959	19,959	—	27,682	16,446	11,237	40,912	—	8,722
barrel/day
Mass Flow, lb/hr	193,635	193,635	254,370	254,370	150,776	103,021	415,923	325,882	90,041
Mole Flow,	2,460	2,460	3,581	3,581	2,109	1,441	4,758	3,770	987
lbmole/hr
Vapor Weight	0.00	0.00	1.00	0.00	0.00	0.00	0.00	1.00	0.00
Fraction
Vapor Mole	0.00	0.00	1.00	0.00	0.00	0.00	0.00	1.00	0.00
Fraction
Enthalpy Flow,	−185.2	−178.2	−221.3	−264.8	−154.6	−105.6	−323.7	−212.3	−67.4
MMBtu/hr
Composition, liq.
vol %
H2O	0.20	0.20	0.16	0.16	0.01	0.01	0.00	0.00	0.00
N-Butane	1.99	1.99	3.53	3.53	3.53	3.53	0.00	0.00	0.00
4O	0.03	0.03	0.05	0.05	0.05	0.05	0.00	0.00	0.00
N-Pentane	28.36	28.36	48.60	48.60	48.67	48.67	4.55	5.16	2.31
Isopentane	25.58	25.58	45.33	45.33	45.39	45.39	0.30	0.33	0.16
Cyclopentane	1.67	1.67	1.93	1.93	1.93	1.93	2.31	2.57	1.33
5O	0.06	0.06	0.11	0.11	0.11	0.11	0.01	0.01	0.00
Hexane	9.51	9.51	0.00	0.00	0.00	0.00	24.07	24.68	21.81
Benzene	1.13	1.13	0.00	0.00	0.00	0.00	2.99	3.10	2.58
22 Methylbutane	0.41	0.41	0.15	0.15	0.15	0.15	1.20	1.32	0.75
23 Methylbutane	0.90	0.90	0.02	0.02	0.02	0.02	2.76	2.95	2.04
2 Methylpentane	6.25	6.25	0.09	0.09	0.09	0.09	19.16	20.50	14.22
3 Methylpentane	3.24	3.24	0.01	0.01	0.01	0.01	9.43	9.98	7.41
Methylcyclopentane	3.26	3.26	0.00	0.00	0.00	0.00	8.07	8.22	7.48
Cyclohexane	2.60	2.60	0.00	0.00	0.00	0.00	5.60	5.51	5.96
6O	0.06	0.06	0.00	0.00	0.00	0.00	0.18	0.19	0.14
C7+	14.74	14.74	0.00	0.00	0.00	0.00	19.37	15.47	33.80
Vapor Phase
Properties
Mole Flow,	—	—	3,581	—	0	—	—	3,770	—
lbmole/hr
Mass Flow, lb/hr	—	—	254,370	—	0	—	—	325,882	—
Actual Volumetric	—	—	8,015	—	0	—	—	7,884	—
Flow, ACFM
Density, lb/ft3	—	—	0.5289	—	0.5630	—	—	0.6889	—
Viscosity, cP	—	—	0.0078	—	0.0073	—	—	0.0085	—
Heat Capacity,	—	—	0.46	—	0.43	—	—	0.49	—
Btu/lb-F.
Thermal	—	—	0.01	—	0.01	—	—	0.01	—
Conductivity,
Btu/hr-ft-F.
Molecular Weight	—	—	71.03	—	68.06	—	—	86.43	—
Liquid Phase
Properties
Mole Flow,	2,460	2,460	—	3,581	2,109	1,441	4,758	—	987
lbmole/hr
Mass Flow, lb/hr	193,635	193,635	—	254,370	150,776	103,021	415,923	—	90,041
Actual Volumetric	596	635	—	837	499	341	1,390	—	298
Flow, USGPM
Std. Vol. Flow,	19,853	19,853	—	27,600	16,384	11,195	40,666	—	8,669
barrel/day
Density, lb/ft3	40.48	38.03	—	37.91	37.69	37.69	37.32	—	37.64
Viscosity, cP	0.2580	0.1861	—	0.1955	0.1898	0.1898	0.1601	—	0.1622
Heat Capacity,	0.5375	0.5852	—	0.5647	0.5675	0.5675	0.6150	—	0.6180
Btu/lb-F.
Thermal	0.0615	0.0554	—	0.0577	0.0571	0.0571	0.0522	—	0.0523
Conductivity,
Btu/hr-ft-F.
Molecular Weight	78.72	78.72	—	71.03	71.51	71.51	87.42	—	91.19
Blend Properties
Viscosity: cSt	0.40	0.31	—	0.32	0.31	0.31	0.27	—	0.27
Std Density: kg/m3	668	668	—	631	631	631	701	—	712
RVP @ 100° F.:	90	90	—	133	133	133	38	—	31
kPa (absolute)
JPG RVP						19
ESTIMATE PSIA
TVP @ 100° F.: kPa	97	97	—	140	140	140	38	—	31
(absolute)
Olefins: vol %	0.50	0.50	—	0.17	0.17	0.17	0.49	—	0.93
Benzene: vol %	1.13	1.13	—	0.00	0.00	0.00	2.99	—	2.58
BTEX: vol %	2.08	2.08	—	0.00	0.00	0.00	4.12	—	4.76
H2S: PPMws	0.0	0.0	—	0.0	0.0	0.0	0.0	—	0.0
C1-C3 Mercaptans:	3	3	—	3	3	3	6	—	4
PPMws
Total Sulfur:	10	10	—	4	4	4	22	—	17
PPMws

TABLE 2.b
Properties of Stream 10-34

								33	34
								CWS to	CWR from
Stream Number	10	11	20	21	22	31	32	Light	Light
	Cool Tower	Light Naphtha	MPS to	Exhaust	Conden-	CWS to	CWR from	Naphtha	Naphtha
Stream Description	Bottoms	to Storage	Reboiler	Steam	sate	Condenser	Condenser	Cooler	Cooler

Overall Properties
Pressure, psig	40	40	150	10	10	50	50	50	50
Temperature, ° F.	116	100	450	239	239	90	95	90	105
Std. Vol Flow (V),	—	—	24.5	3.4	—	—	—	—	—
MMSCFD
Std. Vol Flow (L),	8,721	8,721	—	—	0	0	0	0	0
barrel/day
Mass Flow, lb/hr	90,027	90,027	48,609	6,669	41,940	146,345	146,345	2,903,938	2,903,938
Mole Flow,	987	987	2,698	370	2,328	8,123	8,123	161,195	161,195
lbmole/hr
Vapor Weight	0.00	0.00	1.00	1.00	0.00	0.00	0.00	0.00	0.00
Fraction
Vapor Mole	0.00	0.00	1.00	1.00	0.00	0.00	0.00	0.00	0.00
Fraction
Enthalpy Flow,	−74.4	−75.1	−272.3	−37.9	−278.4	−993.5	−992.8	−19713.8	−19670.4
Composition liq.
vol %
H2O	0.00	0.00	100.00	100.00	100.00	100.00	100.00	100.00	100.00
N-Butane	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
4O	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
N-Pentane	2.30	2.30	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Isopentane	0.16	0.16	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Cyclopentane	1.33	1.33	0.00	0.00	0.00	0.00	0.00	0.00	0.00
5O	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Hexane	21.81	21.81	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Benzene	2.58	2.58	0.00	0.00	0.00	0.00	0.00	0.00	0.00
22 Methylbutane	0.75	0.75	0.00	0.00	0.00	0.00	0.00	0.00	0.00
23 Methylbutane	2.04	2.04	0.00	0.00	0.00	0.00	0.00	0.00	0.00
2 Methylpentane	14.23	14.23	0.00	0.00	0.00	0.00	0.00	0.00	0.00
3 Methylpentane	7.41	7.41	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Methylcyclopentane	7.48	7.48	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Cyclohexane	5.96	5.96	0.00	0.00	0.00	0.00	0.00	0.00	0.00
6O	0.14	0.14	0.00	0.00	0.00	0.00	0.00	0.00	0.00
C7+	33.81	33.81	0.00	0.00	0.00	0.00	0.00	0.00	0.00
Vapor Phase
Properties
Mole Flow,	—	—	2,698	370	0	—	—	—	—
lbmole/hr
Mass Flow, lb/hr	—	—	48,609	6,669	0	—	—	—	—
Actual Volumetric	—	—	2,538	1,833	0	—	—	—	—
Flow, ACFM
Density, lb/ft3	—	—	0.3192	0.0606	0.0606	—	—	—	—
Viscosity, cP	—	—	0.0172	0.0126	0.0126	—	—	—	—
Heat Capacity,	—	—	0.56	0.50	0.50	—	—	—	—
Btu/lb-F.
Thermal	—	—	0.02	0.01	0.01	—	—	—	—
Conductivity,
Btu/hr-ft-F.
Molecular Weight	—	—	18.02	18.02	18.02	—	—	—	—
Liquid Phase
Properties
Mole Flow,	987	987	—	—	2,328	8,123	8,123	161,195	161,195
lbmole/hr
Mass Flow, lb/hr	90,027	90,027	—	—	41,940	146,345	146,345	2,903,938	2,903,938
Actual Volumetric	263	260	—	—	89	294	294	5,829	5,847
Flow, USGPM
Std. Vol. Flow,	8,667	8,667	—	—	2,875	10,031	10,031	199,051	199,051
barrel/day
Density, lb/ft3	42.60	43.12	—	—	59.08	62.11	62.05	62.11	61.93
Viscosity, cP	0.3199	0.3501	—	—	0.2401	0.7606	0.7185	0.7606	0.6446
HeatCapacity,	0.5194	0.5090	—	—	1.0122	0.9980	0.990	0.9980	0.9981
Btu/lb-F.
Thermal	0.0648	0.0662	—	—	0.3962	0.3590	0.3612	0.3590	0.3653
Conductivity
Btu/hr-ft-F.
Molecular Weight	91.20	91.20	—	—	18.02	18.02	18.02	18.02	18.02
Blend Properties
Viscosity: cSt	0.47	0.51	—	—	0.25	0.76	0.72	0.76	0.65
Std Density: kg/m3	712	712	—	—	1,000	1,000	1,000	1,000	1,000
RVP @ 100° F.:	31	31	—	—	7	7	7	7	7
kPa (absolute)
JPG RVP		4.;5
ESTIMATE PSIA
TVP @ 100° F.: kPa	31	31	—	—	7	7	7	7	7
(absolute)
Olefins: vol %	0.93	0.93	—	—	0.00	0.00	0.00	0.00	0.00
Benzene: vol %	2.58	2.58	—	—	0.00	0.00	0.00	0.00	0.00
BTEX: vol %	4.76	4.76	—	—	0.00	0.00	0.00	0.00	0.00
H2S: PPMws	0.0	0.0	—	—	0.0	0.0	0.0	0.0	0.0
C1-C3 Mercaptans:	4	4	—	—	0	0	0	0	0
PPMws
Total Sulfur:	17	17	—	—	0	0	0	0	0
PPMws

Example 3

Study to Determine the Effect of Mixed Pentanes on the Octane Value of a Refined Gasoline Stream

Unleaded regular and premium gasoline blends satisfying the performance characteristics of ASTM D4814-01a were blended with varying amounts of a mixed pentane stream containing 55% n-pentane and 45% iso-pentane (hereinafter referred to as “mC₅”), a 55:45 mixture of the butane and mC₅, a 80:20 mixture of the butane and mC₅, and the resulting blends measured for RVP and octane. The same blends were subsequently mixed with 10% ethanol and their RVP and octane values measured a second time. RVP and octane values of the starting gasoline and resulting blends are reported below in Tables 3.a-3.f.

All RVP values reported in the following examples were measured according to ASTM D 5191. Octane is reported as (R+M)/2, where R equals the research octane number calculated according to ASTM D 2699, and M equals the motor octane number calculated according to ASTM D 2700. Butane used in all blends as n-butane.

TABLE 3.a
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

RVP	5.82	7.25	5.28	6.54
+4.5% mC5	6.64	—	6.05	—
+12% mC5	7.24	8.7	7.24	8.37
+15% mC5	7.82	—	7.31	—

TABLE 3.b
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

RVP	5.82	7.25	5.28	6.54
+3% 55/45	6.92	7.99	6.48	7.75
+8% 55/45	8.37	—	8.48	—
+11% 55/45	9.94	10.83	9.36	10.21

TABLE 3.c
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

RVP	5.82	7.25	5.28	6.54
+2% 80/20	6.61	—	6.44	—
+6% 80/20	8.43	9.7	8.48	9.07
+9% 80/20	9.91	—	9.47	—

TABLE 3.d
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH
Octane	83.2	87.0	91.2	93.1
+4.5% mC5	83.0	—	91.0	—
+12% mC5	83.0	86.6	91.0	93.2
+15% mC5	83.0	—	91.0	—

TABLE 3.e
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH
Octane	83.2	87.0	91.2	93.1
+3% 55/45	83.6	87.2	91.5	93.3
+8% 55/45	83.6	—	91.2	—
+11% 55/45	83.5	87.5	91.1	93.5

TABLE 3.f
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH
Octane	83.2	87.0	91.2	93.1
+2% 80/20	83.4	—	91.2	—
+6% 80/20	83.5	87.5	91.0	93.6
+9% 80/20	83.5	—	90.8

TABLE 3.g
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

RVP	11.12	12.89	11.2	11.98
+4% mC5	11.4	12.4	11.24	12.1
+7% mC5	11.37	12.63	11.5	12.2
+12% mC5	11.66	12.83	11.56	12.49

TABLE 3.h
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

RVP	11.12	12.89	11.2	11.98
+6% 55/45	12.3	13.87	12.46	13.16
+8% 55/45	13.05	14.21	13.47	14.14
+9% 55/45	13.34	14.68	13.71	14.27

TABLE 3.i
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

RVP	11.12	12.89	11.2	11.98
+9% 80/20	14.17	15.16	13.94	13.84
+12% 80/20	15.32	15.75	14.62	14.24
+13% 80/20	15.58	16.82	14.89	15.59

TABLE 3.j
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

Octane	84.1	87.4	92.3	94.4
+4% mC5	87.9	87.6	92.4	94.5
+7% mC5	87.8	87.3	92.4	94.4
+12% mC5	87.5	87.1	92.2	93.9

TABLE 3.k
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

Octane	84.1	87.4	92.3	94.4
+6% 55/45	84	87.6	92.5	94.5
+8% 55/45	84.1	87.5	92.3	94.1
+9% 55/45	84.2	87.5	92.2	94.1

TABLE 3.l
	CBOB	CBOB + EtOH	PBOB	PBOB + EtOH

Octane	84.1	87.4	92.3	94.4
+9% 80/20	84.3	87.6	92.4	94.4
+12% 80/20	84.2	87.6	92.4	94.3
+13% 80/20	84.3	87.6	92.5	94.1

Three notable findings emerge from the foregoing tables. The first emerges from Table 3.d, wherein it is seen that isopentane stabilizes the impact of n-pentane on the resulting blend, across the entire range of quantities tested. In site of a neat octane value of approximately 65 for n-pentane, the n-pentane added to the blend had very little impact on the octane of the resulting blend due to the presence of isopentane.

The second finding relates to the impact of the mixed hydrocarbons (C₄ and C₅) on octane as the amount of pentanes increases, when added to a hydrocarbon stream that is eventually mixed with ethanol. This can be seen most clearly from the data in Tables 3.e and 3.f. As a general rule, increasing the quantity of mixed hydrocarbons (C₄ and C₅) either decreased the final octane value slightly or had no effect on the final octane value of the mixture. However, when ethanol was added to the blend a reversal to the trend was observed, with the ethanol blended octane value increasing with the additional mixed hydrocarbons. Indeed, synergy is observed at various blending rates, and is observed sooner (from a pentane standpoint) when the pentane is mixed with larger proportions of butane.

The third finding relates to the consistency of the impact on octane as the ratio of butane and pentane components is varied. In fact, varying the ratio of butane to mixed pentanes had very little impact on the octane value of the resulting blend, demonstrating that RVP can be used as the controlling variable when a range of butane/pentane batches is added to the gasoline.

Throughout this application, various publications are referenced. The disclosures of these publications are hereby incorporated by reference in order to more fully describe the state of the art to which this invention pertains. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.