No title

Chemistry and Technology of Fuels and Oils, Vol. 43, No. 1, 2007

CURRENT PROBLEMS

RUSSIAN ENVIRONMENTALLY CLEAN DIESEL FUELS OF EUROPEAN QUALITY V. G. Rassadin, O. V. Durov, G. G. Vasil’ev, N. G. Gavrilov,

UDC 665.753

O. Yu. Shlygin, and N. M. Likhterova

The results of screening tests of foreign catalysts from Criterion, Haldor Topsoe, and Akzo Nobel for production of EN–590 (Euro–2, Euro–3) diesel fuels are examined. The effectiveness of revamping the LCh–24/2000 unit for processing these fuels using the Akzo Nobel catalyst package was demonstrated. The physicochemical characteristics of the diesel fuel with additives that satisfies the requirements of GOST R 52368-2005 for fuel with a residual sulfur content of less than 50 ppm are reported. The high price of crude oil all over the world allowed diversifying the processing schemes for domestic oil refineries (OR) at the beginning of 2000 to increase the competitiveness of their products on world markets. The tendency to produce petroleum products of European quality at Russian OR became irreversible after the advent of the law on “Technical Regulation” (June 26, 2003). Revamping and retooling of motor fuel production units are now being conducted at almost all Russian OR [1–10]. The leading oil companies have perfected technologies for production of high–quality motor fuels in two directions. TNC and Angara Oil Company have primarily attempted to fully utilize domestic developments in the area of technology, catalysts, and equipment in developing a strategy for retooling and revamping existing fuel production plants. LUKOIL has taken into account world experience, including purchase of licenses for the most promising technologies, equipment, and catalysts from the leading firms in the USA and Western Europe. Guarantees of the reliability of operation and high quality of the equipment and catalysts allowed organizing production of export products of European quality at OR in record times, which expanded the amount of investments for further development of their refineries combined with the high crude oil prices. ____________________________________________________________________________________________________ LUKOIL OJSC-Nizhegorodnefteorgsintez. Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 1, pp. 3 – 9, January – February, 2007. 0009-3092/07/4301–0001 © 2007 Springer Science+Business Media, Inc.

1

Table 1

Hydrogenation product obtained on catalyst 448 T@ with beads with diameter of, mm GKD-300

837

828

829

828

829

830

832

10200 83

9700 97

100

600

170

500

1300

540

70,1

74,2

76

79,4

77,4

74

0,93 22,9

1,06 22

1,4 21,6

1,23 21,1

1,08 23,2

0,8 27,5

1,02 32,5

53

55

50

54

54

54

52

0,26 aromatic (including thiophene derivatives) 32,5 Cetane number 51

424 T@

839

TK-554

GM-85 Co

Density at 20°C, kg/m3 Content total sulfur, ppm nitrogen, ppm hydrocarbons, wt. % unsaturated

GKD-300

Indexes

TK-554, 424 T@, 448 T@, GM-85 Co

Feedstock for certification of catalysts

1.3

2.5

The strategy for developing production of high–quality diesel fuels created at LUKOIL includes four stages: • hydrorefining of straight–run diesel cuts on high–efficiency foreign catalysts that allow obtaining products with a residual sulfur content of less than 350 (version I) and less than 50 (version II) ppm in existing hydrorefining units; • combining hydrorefining and hydroisomerization of straight–run diesel cuts with a residual total sulfur content of less than 10 ppm and less than 11% polycyclic aromatic hydrocarbons in newly constructed hydrotreating units based on licenses from the leading foreign firms in this sector; • combining desulfurizing, denitration, and hydrodearomatization of catalytic gasoils, coking, visbreaking in complexes for exhaustive refining of crude oil using catalysts and technologies from the leading foreign companies; • hydrocracking of vacuum straight–run and secondary gasoils with a mandatory system for removal of high–molecular–weight polycyclic aromatic hydrocarbons [11]. Within the framework of this strategy, LUKOIL is the developer of national standards for production of EN–228 automotive gasolines (GOST R 51866–2002), domestic Jet A–1 fuel (GOST R 52050–2003), and EN–590 diesel fuel (GOST R 52368–2005). Development of national standards for motor fuels of European quality corresponds to the requirements of the law on “Technical Regulation” and is totally harmonized with the text of the draft special technical regulation “Requirements for Gasolines, Diesel Fuel, and Individual Fuel–Lubricant Materials.” The latter has been approved and will become a Federal law in 12 months after the date of official publication. LUKOIL is thus successively implementing diversification of oil refinery technology in view of world trends. According to the strategy developed, the first stage of diversification of diesel fuel production technology is being implemented at LUKOIL–Nizhnegorodnefteorgsintez Co. User demand in internal and external markets for 2

Table 2

Feedstock for testing KF–757 catalyst

Hydrogenation product on KF–757 catalyst

IBP 10 % 50 %

111 183 277

164 242 313

90 %

358 404

368 412

15289

10**

Indexes Distillation, °C

EP Content*, ppm total sulfur methylthiophenes C2–C4 thiophenes

49

Not detected

2524

same

benzothiophenes C1–C5 benzothiophenes

340

same

8088

same

4287 972

217

43.5

44.5

C1–C5 dibenzothiophenes nitrogen Cetane index Notes.

* Determined by atomic–emission analysis

** Determined by XFA

the products manufactured by the company is being evaluated to determine the niche in sales markets to 2014. In conducting the market analysis, the following hypotheses were advanced concerning the development of internal and external markets: • the increase in the real earnings of the population will be up to 6% a year; • the passenger car fleet will increase by 40% by 2010; • production of passenger cars will increase to 2–2.5 million units by 2010 and imports will crease to 400,000 units; • the increase in demand for motor fuels in Russia will be determined by the growth rate of the Russian GDP, slightly exceeding it; • exports of gasoline to Europe will be limited except perhaps for a small amount of high–octane gasoline to Baltic countries; • the demand for diesel fuel for internal and external markets will increase. According to market studies, potential annual sales volumes for the basic petroleum products for LUKOIL–Nizhegorodnefteorgsintez by 2014 are projected at, in millions of tons: 2.8–2.9 for gasoline; 1–1.5 for jet fuel; 4–5 for diesel fuel; 2.5–3 for boiler fuel. Based on an analysis of sales markets and the status of the available production capacities for hydrorefining of middle–distillate fuel cuts at the company, the LCh–24/2000 unit with output of 2 million tons/year in feedstock started up in 1993 was selected for revamping. The unit includes the following blocks: reactor, hydrogen product stabilization; treatment of circulating hydrogen–containing gas (CHCG) and hydrocarbon gas to remove hydrogen sulfide, ammonia, and water with a solution of monoethanolamine (MEA); regeneration of MEA. Before beginning revamping, a bid for selecting the catalyst for hydrotreating of diesel cuts to obtain EN–590 fuel was conducted between the licensing companies Criterion, Haldor Topsoe, Axens, and Akzo Nobel.

3

Sulfur content, ppm

Sulfur content, ppm

Temperature,°C

Temperature,°C

Fig. 1. Sulfur content in hydrogenation product as a function of the temperature in the reactor for catalysts: a) TK–554; b) 424T@; c) 448 T@ with granules 1.3 mm (curve 1) and 2.5 mm in diameter (curve 2); d) GKD–300 (curve 1) and GM–85 Co (curve 2); e) STARS series KF–757. The

foreign

catalysts

TK–554

(Haldor

To p s o e ) ,

424T@,

448

T@

(Criterion),

and STARS series KF–757 (Akzo Nobel) in comparison to the domestic catalysts GM–85 Co (VNIIOS NK [All–Russian Scientific–Research Institute of Organic Synthesis Oil Co.]) and GKD–300 (VNII NP [ All–Russian Scientific–Research Institute of the Petroleum Industry]). The tests were conducted at pressure of 3 MPa, feedstock space velocity of 4 h –1 , CHCG to sulfur ratio of 250 nm 3/m 3. The domestic catalyst GKD–300 was tested in more severe conditions: pressure of 4 MPa, feedstock space velocity of 3 h –1 . To obtain hydrogenation products with a residual sulfur content of less than 50 ppm, the feedstock space velocity did not exceed 2–2.5 h –1 . The physicochemical properties of the feedstock used in certification of the catalysts are reported in Tables 1 and 2. In testing KF–757 catalyst on a wide middle–distillate cut that included heavy naphtha cuts (IBP–10%), kerosene and diesel cuts with a high (404°C) end point by atomic emission analysis, we were able to follow the degree of removal of thiophene derivatives of different molecular weight. 4

Content, wt. %

TK–554 424T@ 448 T@ 448 T@ GM–85 Co GKD–300 1.3 2.5 Fig. 2. Coke (1) and sulfur (2) content on catalysts after testing at 380°C. The dependences of the total sulfur content in the hydrogenation products on the temperature in the reactor were established during the experiments (Fig. 1). The residual sulfur content in the hydrogenates was determined by x–ray fluorescence analysis (XFA). The data obtained show that KF–757 catalyst exhibits the highest activity in reactions of hydrogenolysis of sulfur compounds. The physicochemical properties of the hydrogenation products with a minimum content of sulfur compounds obtained in testing the catalysts are reported in Tables 1 and 2. The coke and sulfur content was determined after completion of the experiments at a temperature of 380 on the domestic catalysts and Criterion and Haldor Topsoe catalysts. As the data show (Fig. 2), the domestic catalysts have a high tendency to form coke deposits while GM–85 Co catalyst is also characterized by a low degree of sulfiding. As a result of testing the catalysts and generalizing the licensing company data, preference was given to Akzo Nobel. This company’s catalyst package was purchased and loaded in 2003: KG–55, KF–542, KF–841, KF–757. The characteristics of these catalysts are reported in Table 3. The total volume loaded was 77 m 3. The loading diagram is shown in Fig. 3. Before loading the catalyst system, partial revamping of reactor R–201 and individual units in the installation was conducted to increase its efficiency: • a new DUPLEX distribution tray from Akzo Nobel was installed in the reactor; • the heat–exchange conditions were improved in the lower part of tower K–205 in the MEA regeneration block to reduce the concentration of hydrogen sulfide in CHCG; • defects in feeding MEA to tower K–205 were identified and eliminated; • discharge of treated diesel fuel into the PLC system; • the vapor cooling conditions in stabilization tower K–201 were improved and the possibility of fuel entering the circulating water supply system was eliminated; • the efficiency of operation of furnace P–201 was increased; • a separate line was installed for taking environmentally clean diesel fuel (less than 350 and less than 50 ppm sulfur) off the unit. Installation of new lines for taking stable hydrogenation product off the unit was caused by the high dissolving power of the hydrogenation product with respect to deposits in the pipelines that previously transported hydrogenation products with a higher content of sulfur compounds and resins. These data were obtained as a result of many years of domestic experience in production of thermostable RT and T–6 jet fuels. KF–757 catalyst was delivered in oxide form and impregnated with a special composition that fixes the position of the active sites on the support. In this respect, sulfiding was allowed only by the feedstock. Sulfiding 5

Hose

STARS series KF-757-3Q

same

KF-841-2E

Leak-proof

same

KF-542-5R

STARS series KF-757-1.5E

Hose

Loading method

KG-55

Catalyst

Volume loaded in reactor, m3 1.02

64.13

8.16

2.04

1.53

CoO/ MoO3

CoO/MoO3 on Al2O3

Ni/Mo on Al2O3

MoO3/NiO/CoO on Al2O3

SiO2/Al2O3

Chemical composition

in laboratory determination 750

780

780

670

880

668

694

686

596

—

in hose loading

Bulk density, kg/m3

772

803

803

—

—

in leak-proof loading

Table 3

647

795

686

637

647

real

6 Ring

19.2 × 9.5

6×3

2.6 × 5.1

1.4 × 3.5

Quadrilobe

same

Cylinder

Segmented ring

2.1×4.5

Granule shape

Granule size, mm

same

Protective layer to trap particulate contaminants and pollution, slowing increase in pressure drop Hydrogenation of unsaturated compounds, trapping of particulate contaminants (has a high volume of free space), improving feedstock stream distribution Exhaustive denitration and hydrogenation, trapping of metals, improving feedstock stream distribution Exhaustive hydrotreating of middle distillates to 50 ppm sulfur content

Application

15

15

10

5

–

Required sulfur content, %

was conducted according to the company’s recommendations for straight–run diesel cut with a 0.9 wt. % sulfur content. After sulfiding of the catalyst and entry of the unit into normal operation, a fixed run in two regimes that ensured production of diesel fuel with a residual sulfur content of less than 350 ppm (version I) and less than 50 ppm (version II) was conducted. The results of the two versions of runs (Table 4) correspond to Akzo Nobel recommendations primarily with respect to the sulfur content. In charging feedstock at 310 m 3/h, the sulfur content in the product was on

Layer number

Catalyst brand

Layer height, mm

Layer volume, m3

Beads with diameter of, mm 1

16 – 20

690

–

2

10

50

–

3 4

6 KF-757-3Q

90 100

– 1.02

5

KF-757-1.5E

6250

64.13

6

KF-841-2E

795

8.16

7

KF-542-5R

200

2.04

8

KG-55

150

1.53

8325

76.88

Total

Fig. 3. Diagram of loading Akzo Nobel catalyst in reactor 201 (internal diameter of 3616 mm, height of 11.192 mm, volume of 114.9 m3). 7

average 310 ppm, and the mean weighted temperature in the catalyst bed was 334°C, which is 16°C lower than the temperature predicted by the company. At feedstock input of 230 m 3/hk (guaranteed input of 210 m3/h), the residual sulfur content was 31 ppm and the weighted mean temperature in the catalyst bed was 10° lower than expected. D u r i n g t h e r u n , i t was not possible to maintain the concentration of hydrogen in the CHCG at 80 vol. % (contract data) due to the low hydrogen content (76 vol. % on average) in the fresh HCG entering the unit. It was only 69 vol. %, which decreased the partial hydrogen pressure at the reactor inlet from 2.4 (initial data) to 1.9 MPa. This negatively affected the work of the catalyst system and increased the rate of coke formation on the catalyst. D u r i n g t h e c o n t r o l r u n i n l o a d i n g f e e d s t o c k a t 3 1 0 m 3/ h , t h e p r e s s u r e d r o p i n t h e r e a c t o r was 0.31 MPa, i.e., slightly higher than predicted (0.24 MPa), which was due to the following causes: increasing the total volume of actually charged catalyst from 70 to 77 m 3 ; a low hydrogen content (69–70 vol. %) in the circulating gas, which increased the viscosity of the gas and the CHCT flow velocity to 86–96,000 nm 3/h (according to calculated data, 75,000 nm3/h at an 80 vol. % concentration of hydrogen). All of these factors caused a significant increase in the pressure loss in the catalyst bed and an increase in the pressure differential. After completion of the fixed run, HCG began to be fed from the reforming unit Recovery Place block to the LCh–24/2000 unit with continuous regeneration of the catalyst. The concentration of hydrogen in the HCG from this unit was 90–91 vol. %, which allowed reducing consumption of hydrogen and blowing off HCG. Table 4

Data from fixed run according to version Indexes

I

II

programmed

real

programmed

real

1.6 (max) 30

79

Table 2

cso, wt. %

ηef at ε = 9 sec-1, Pa⋅sec

σ0, Pa

r

43.5

0.24

1.87

0.991

46

0.43

3.51

0.997

48

0.86

5.14

0.998

49

1.42

10.91

0.997

50

2.19

15.79

0.996

According to another method, brown coal or peat is first dried and then a suspension fuel is made from it. Different methods are used to reduce the natural moisture content of brown coals. One of several methods widely used in heat and power engineering is to dry the coal at a low temperature (100-160°C) in an atmosphere of waste stack gases with simultaneous grinding to obtain a dispersion for powder combustion. The residual moisture content of the product obtained is 10-20% (“cake”) [40, 41]. There are technologies for more exhaustive treatment of brown coal, for example, Hot Water Drying (HWD) [42] and its analogs [43-46]. Exhaustive drying is conducted in closed vessels in conditions of high temperatures (240-400°C) and pressures of the liberated gases. In addition to elimination of water, carboxyl groups decompose with liberation of carbon dioxide from the structure of the coal and resinous substances and oils. These components are strongly retained on the surface of the coal in micropores and make it hydrophobic. After such treatment, brown coal becomes similar to bituminous coals in the character of the surface and heat value and suitable for manufacturing suspension fuel. The essence of our method of obtaining WOCS from brown coal [28, 47, 48] consists of increasing the degree of surface hydrophoby by blocking some of the oxygen-containing surface groups in application of liquid hydrocarbons (diesel fuel, GOST 1667–68) to the surface of the solid hydrocarbons and subsequent addition of an aqueous solution of a chemical additive – sodium sulfohumate. The mixture is mixed with a mechanical stirrer in the intensively turbulent mode (rotation rate of 1500 min -1). Brown coal (“cake”) from the Aleksandriisk deposit (Ukraine) prepared for powder combustion at Aleksandriisk TEPP-3 was used for fabricating the suspensions. Addition of petroleum hydrocarbons to the fuel composition increases its heat value. This method also allows increasing the degree of hydrophoby of brown coal powder as a result of addition of oil phase and attaining the surface hydrophilic-hydrophobic balance required for formation of coagulation structures in the suspensions. Optimizing their composition, i.e., searching for the ratios of components at which the physicochemical ratios of components best satisfy the process requirements, is an important stage in preparation of industrial suspensions. Production of WOCS includes determination of the region of optimum concentrations of the chemical additive, oil, and solid phases. In addition, a search is conducted for the granulometric composition of the disperse phase at which the best rheological parameters of the suspensions are attained. The regions of optimum concentrations of each component were determined as a result of studying the rheological properties of WOCS in subsequent variation of the concentration of each of the three components [28]. The rheological characteristics of brown-coal WOCS as a function of the concentration c so of solid phase at the optimum concentrations of the suspension found (9% oil phase, 0.275% sodium sulfohumate) and the optimum granulometric composition of the solid phase: maximum average particle size of 80 mm, are reported in Table 2. The effectiveness of the plasticizing effect of chemical additives in suspension fuels was evaluated based on the ability of the SF to ensure viscoplastic flow of the suspension [26]. The values of correlation coefficient

80

r in the equation of viscoplastic flow: σ = σ 0 + η efε, are reported in Table 2. The high values indicate the correspondence of the chemical additive used – sodium sulfohumate – to the effectiveness criterion. There are published examples of preparation of suspensions from soft brown coals previously treated by HWD or similar technologies that attain an approximately 60% concentration of combustible components in the system. The suspensions contain SF that improve their stability and fluidity [42-46]. Using the proposed method of obtaining a suspension and sodium sulfohumate as chemical additive, concentrations of solid phase (in terms of dry combustible mass) equal to 50 wt. % and rheological parameters that satisfy the requirements of the technology can be attained: η ef = 2.19 Pa⋅sec; σ = 15.8 Pa; sedimentation stability for more than 30 days; resistance to formation of aggregates. The total combustible hydrocarbon content – coal and oil phase – reaches 59%. One possible method of preparing three-phase colloidal fuels from brown coals can thus be to modify their hydrophilic and highly porous surface by incorporating an oil phase with addition of sodium sulfohumate (SF) as a regulator of the rheological properties of the suspension. A fuel system can be obtained with industrially acceptable physicochemical parameters and a concentration of combustible components of the same order as in using HWD and analogous technologies, but with much lower power consumption for exhaustive drying of wet brown coals. In conclusion, we note that the problem of preparing colloidal types of fuel is solved individually and often empirically in each concrete case. The properties of such fuels can be predicted and regulated only by knowing the mechanisms of physicochemical processes in heterogeneous systems. REFERENCES 1. A. L. Lapidus and A. Yu. Krylov, Coal and Natural Gas – Sources for Production of Man-made 2.

Liquid Fuel and Chemical Products [in Russian], Znanie, Moscow (1986). Yu. G. Frolov, Course in Colloid Chemistry. Surface Phenomena and Disperse Systems [in Russian],

3.

Khimiya, Moscow (1982). P. A. Rebinder, Surface Phenomena in Disperse Systems. Physicochemical Mechanics. Selected

4.

Works [in Russian], Khimiya, Moscow (1979). V. N. Deryagin, Usp. Khim., No. 4, 675-721 (1979).

5.

N. B. Ur’ev, Physicochemical Principles of the Technology of Disperse Systems and Materials [in Russian], Khimiya, Moscow (1988).

6. 7.

USA Patent No. 4560391. I. A. Tarkovskaya, Oxidized Coal [in Russian], Naukova Dumka, Kiev (1981).

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pp. 467-478. J. Dooher, R. Genberg, R. Lippman, et al., Mech. Eng., 98, No. 11, 36-41 (1976).

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L. Bartha, N. Nemes, N. Kriko, et al., Hung. J. Ind. Chem., 16, No. 4, 407-417 (1988). H. Terada, F. Koda, and T. Hishinuma, Inst. Chem. Eng. Symp. Ser., No. 95, 413-426 (1985).

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S. L. Khil’ko, E. V. Titov, A. F. Popov, et al., Khim. Promyshl. Ukr., No. 4 (33), 7-10 (1999). S. L. Khil’ko and E. V. Titov, Khim. Tverd. Topl., No. 1, 78-87 (2001).

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S. L. Khil’ko and E. V. Titov, Zh. Prikl. Khim., No. 8, 1383-1386 (2000). S. L. Khil’ko and E. V. Titov, Neft. Gaz. Promyshl. (Kiev), No. 2, 56-59 (2001).

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K. Fu, D. Guo, and L. Yang, in: Coal Utilization & Fuel Systems, 21 st Int. Technic. Conf., Marth, Clearwater (1996), p. 259.

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French Patent Application No. 2595711. S. L. Khil’ko and E. V. Titov, in: Vibrotechnology-2003 Scientific Works [in Russian], NPO BOTUM,

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Odessa (2003), pp. 89-90. US Patent No. 4780110.

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Japanese Patent Application No. 57-195797. Japanese Patent Application No. 54-68804.

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V. I. Ugursal and G. D. Mackay, Int. J. Energy Res., 15, 637-652 (1991). D. Böcker and H. Krensing, Braunkohle, 34, No. 1, 1-5 (1982).

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K. Hamerak, Techn. Heute, No. 7, 16-25 (1980). Andrew Gaved, World Coal, No. 2, 19-28 (1995).

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E. G. Gorlov, G. S. Golovin, and O. V. Zotova, Khim. Tverd. Topl., No. 6, 117-125 (1994). G. N. Delyagin, E. I. Rukin, and T. P. Gorskaya, Ibid., No. 4, 133-136 (1977).

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82