Hydrocracking and Hydrotreating

7 Synthoil Process and Product Analysis

Downloaded by UNIV OF CALIFORNIA SAN DIEGO on November 22, 2015 | http://pubs.acs.org Publication Date: June 1, 1975 | doi: 10.1021/bk-1975-0020.ch007

HEINZ W. STERNBERG, RAPHAEL RAYMOND, and SAYEED AKHTAR Energy Research and Development Administration, Pittsburgh Energy Research Center, 4800 Forbes Ave., Pittsburgh, Penn. 15213

Many power generating stations i n the United States burn im ported fuel oils, instead of coal, to meet environmental protec tion regulations. Large quantities of fuel oils are imported annually at considerable strain to the nation's balance of pay ment, a strain that could be removed by burning environmentally acceptable coal-derived fuels prepared from internal resources. Towards this end, the Energy Research and Development Administra tion is developing a process known as the SYNTHOIL process to convert coal to a low-sulfur, low-ash utility fuel. In the process, coal is liquefied and hydrodesulfurized catalytically in a turbulent-flow, packed-bed reactor (1-3). The gross liquid product on centrifugation yields a nonpolluting fuel oil suitable for power generation. The results of a study of the chemical composition and viscosity of the product oils obtained at differ ent operating conditions are presented in this paper. The inter relationship of chemical composition and viscosity i s of special interest in view of the importance of the latter in centrifugation of the gross liquid products and in pipeline transportation of the product oil. Plant and Operating Conditions The flowsheet of a 1/2-ton (slurry) per day SYNTHOIL bench scale plant, currently i n operation at the Energy Research and Development Administration laboratory in Bruceton, Pennsylvania, is shown i n figure 1. The v e r t i c a l l y placed reactor is made of two interconnected stainless steel tubings of 1.1-inch ID χ 14.5-ft long each. The upper end of the f i r s t section i s connected to the lower end of the second section with a 5/16-inch ID empty tubing. Thus, the plant may be operated with one or both sections of the reactor packed with catalyst while the fluids flow upwards through each. Hydrogen and a slurry of 35 to 45 percent coal i n recycle o i l are introduced concurrently in a 3-inch ID χ 11-ft long preheater packed with 3/4-inch χ 3/4-inch ceramic pellets which 111 In Hydrocracking and Hydrotreating; Ward, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1975.


112

HYDROCRACKING AND HYDROTREATING

proirote heat t r a n s f e r . The heated feed stream enters the r e a c t o r at the lower end of the f i r s t s e c t i o n and the product stream e x i t s at the upper end of the second s e c t i o n . The l i q u i d s and unreacted s o l i d s are separated from the gases and c e n t r i f u g e d to o b t a i n the product o i l . The gases, a f t e r scrubbing out H2S and NH3, are r e c y c l e d without d e p r e s s u r i z a t i o n . The flow of E2 through both the preheater and the r e a c t o r i s i n t u r b u l e n t regime. The o p e r a t i n g c o n d i t i o n s f o r the three runs FB-38, FB-39, and FB-40, the r e s u l t s from which are discussed i n t h i s paper, are given i n t a b l e I . The l e n g t h of the 1 . 1 - i n c h ID r e a c t o r was 29 f t i n run FB-38 and 14.5 f t i n FB-39 and FB-40. Runs FB-38 and FB-39 were both conducted at 4,000 p s i but the r e a c t o r temperature was 4 1 5 ° C i n FB-38 and 4 5 0 ° C i n FB-39. Run FB-40 was conducted at 2,000 p s i and 4 5 0 ° C . TABLE I . -

Run numbers and operating

conditions FB-39

FB-40

29

14.5

14.5

11

5.5

5.5

4,000

4,000

2,000

415

450

450

Feed r a t e o f (35 c o a l + 65 r e c y c l e oil) slurry, lb/hr

25

25

25

Time on stream, h r

30

380

360

Run No.

FB-38

Length of the 1 . 1 - i n c h ID reactor, ft Charge weight of C o - M o / S i 0 2 - A l 0 catalyst, lb 2

3

Plant pressure, psig Reactor temperature,

0

C

The a n a l y s i s of the c o a l used i n these runs i s given i n table II. The c o a l contained 5.5 percent s u l f u r and 16.5 percent ash. The p y r i t i c s u l f u r i n c o a l was 3.08 percent and the organic s u l f u r 1.95 p e r c e n t . Product A n a l y s i s The l i q u i d products were c o l l e c t e d i n 4-hour batches, c e n t r i fuged, sampled, and analyzed f o r asphaltene, o i l , elementary composition (C, H , N , S ) , a s h , s p e c i f i c g r a v i t y , and v i s c o s i t y . In runs FB-38 and FB-40, the asphaltene content i n c r e a s e d w i t h time. In run FB-39, on the other hand, the asphaltene content decreased during the f i r s t 120 hours from 18 percent to 7 p e r c e n t , remained around 7 percent f o r about 60 h o u r s , and

In Hydrocracking and Hydrotreating; Ward, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1975.

STERNBERG

E T


TABLE I I . -

A L .

Synthoil Process

Analysis

o f feed c o a l ,

Proximate a n a l y s i s , wt Moisture Ash V o l a t i l e matter F i x e d carbon U l t i m a t e a n a l y s i s , wt Hydrogen Carbon Nitrogen Oxygen Sulfur Ash Forms o f s u l f u r , wt Sulfate Pyritic

as

received

pet 4.2 · 36.2 43.1

1

6

5

pet 6

4.8 · I · 11.3 · ·

0

7

2

1

5

5

6

5

pet

Organic C a l o r i f i c value, Btu/lb Rank:

1

7

°-^ 3.08 ·

·

1.95 11,020

hvBb

A b l e n d from Kentucky seams #9, 11, 12, and 13 which mined t o g e t h e r . Ohio County, Western Kentucky.


are


114

HYDROCRACKING AND HYDROTREATING

during the l a s t 200 hours i n c r e a s e d from 7 percent to 25 p e r c e n t . The analyses o f some of the samples c o l l e c t e d from runs FB-38, FB-39, and FB-40 are l i s t e d i n t a b l e s I I I , IV, and V . I n s p e c t i o n of the data shows that the v i s c o s i t y o f the product o i l i n c r e a s e s w i t h asphaltene content. To l e a r n more about the nature o f asphaltenes and t h e i r e f f e c t on v i s c o s i t y , we f r a c t i o n ated samples of product o i l from runs FB-38 and FB-40 according to the scheme shown i n f i g u r e 2. U l t i m a t e analyses and molecular weights o f the v a r i o u s f r a c t i o n s a r e shown i n t a b l e s V I , V I I , and V I I I . In a d d i t i o n to heavy o i l and asphaltene, these t a b l e s a l s o l i s t p y r i d i n e s o l s and p y r i d i n e i n s o l s . These two f r a c t i o n s are always lumped together as "benzene i n s o l s " , but we separated the benzene i n s o l s (toluene i n s o l s i n our case) i n t o a p y r i d i n e s o l u b l e and a p y r i d i n e i n s o l u b l e f r a c t i o n . I t i s a common p r a c t i c e to measure the e f f i c i e n c y of a c o a l l i q u e f a c t i o n process by the percent coal-to-benzene s o l s conversion on a m o i s t u r e and a s h - f r e e b a s i s , the assumption being that the benzene i n s o l u b l e m a t e r i a l i s unreacted c o a l and, by i m p l i c a t i o n , that i t i s not s o l u b l e i n the product o i l and does not c o n t r i b u t e to i t s v i s c o s i t y . These assumptions are m i s l e a d i n g . Tables V I , V I I , and V I I I show that i n a l l cases more than 50 percent of the toluene i n s o l s are p y r i d i n e s o l u b l e and therefore cannot be considered unreacted c o a l . I t i s only the p y r i d i n e i n s o l s that may be unreacted c o a l , carbon, or ash. Moreover, removal of the toluene i n s o l s r e s u l t s i n a considerable decrease i n the v i s c o s i t y o f the product o i l . F o r example, the v i s c o s i t y of a product o i l (FB-40, batch 88) dropped from 1,433 to 907 a f t e r removal o f 8.1 percent toluene i n s o l s . I t i s reasonable to assume that o f the 8.1 percent toluene i n s o l s removed, o n l y the 4.8 percent p y r i d i n e s o l s are r e s p o n s i b l e f o r t h i s decrease i n viscosity. A f u r t h e r and much l a r g e r decrease i n v i s c o s i t y occurred when the asphaltenes, r e p r e s e n t i n g 40.2 percent o f the sample, were removed. The v i s c o s i t y then dropped from 907 to 16, as shown i n f i g u r e 3. TABLE I I I . -

Batch No.

Analyses o f c e n t r i f u g e d l i q u i d product samples taken d u r i n g run FB-38

Vis Sp g r , c o s i t y , SSF at 60°F/ 60°F 180° F

OBI

1

Analyses5, Wt pet As phal C O i l Ash tenes

H

Ν

S

9.2

0.8

0.36

1

1.061

39.4

2.6

21.2

75.3

0.9

87.4

4

1.064

44.3

2.2

22.8

73.8

1.2

86.6

9.1

0.8

0.42

7

1.079

85.6

2.8

24.3

70.9

2.0

85.9

8.9

0.8

0.56

Organic benzene

insolubles


7.

STERNBERG

TABLE IV.-

E T

A L .

Synthoil Process

115

Analyses o f c e n t r i f u g e d l i q u i d product samples taken from run FB-39 Analyses, wt pet

S


Batch No.

1

P gr, V i s 60°F/ c o s i t y 60°F SSF

OBI

Asphaltenes

1

O i l Ash

_C

_H_

_N_

_S

1

1.082

21.5 a t 180° F

2.4

18.0

79.1

0.50 88.8

8.5

0.8

0.30

31

1.023

29.1 a t 77° F

0.4

7.2

92.3

0.01 88.7

9.5

0.6

0.17

49

1.034

67.2 a t 77° F

0.9

11.4

87.6

0.10 88.1

9.3

0.8

0.14

91

1.094

32.5 a t 180° F

1.6

25.4

71.9

1.06 86.5

8.4

1.2

0.51

Organic benzene i n s o l u b l e s

TABLE V.-

Batch No.

Analyses o f c e n t r i f u g e d l i q u i d product samples taken d u r i n g run FB-40

VisSp g r , c o s i t y , 60°F/ SSF a t 60°F 180° F OBI

1

Analyses, wt pet Asphaltenes O i l Ash

_C

_H__

_N_

_S

1

1.060

13.5

1.1

17.3

81.4

0.2

88.5

8.6

1.0

0.22

43

1.130

56.2

4.6

29.4

64.3

1.7

86.5

7.5

1.5

0.55

90

1.146

75.7

5.7

28.9

62.5

2.9

85.3

7.3

1.6

0.71

Organic benzene i n s o l u b l e s


116

HYDROCRACKING AND HYDROTREATING Reactor Recycle oi

Flare stack


COAL-

»H S,NH 2

Scrubber Furnaces-^

Gas meter

Centrifuge

Oil

—

Whole product

H 0 9

Light oil Cake

-Or

Recycle gas N E T P R O D U C T OIL

compressor

Figure 1. Synthoil pilot plantflowsheet

Centrifugea liquid product

Toluene

Toluene insolubles

Toluene solubles

Pyridine

Pentane

Pyridine

Pyridine

Pentane

Pentane

insolubles

solubles

insolubles (asphaltenes)

solubles (oil)

Figure 2. Fractionation scheme for centrifugea liquid product (CLP)


3 l

H 0 2

In Hydrocracking and Hydrotreating; Ward, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1975. 81.97

2.6

2.2

Pyridine solubles

Pyridine insolubles

In c e n t i s t o k e s

85.44

23.5

Asphaltenes

89.01

71.7

C

Oil

Fraction

2.03

0.91

0.77

1.12

6.78 5.69

0.18

0.43

9.69

Ultimate a n a l y s i s , Ν S H

71.9

2.68

0.36

0.01

wt pet Ash

0.95 0.83

6.72

1.30

H/C

5.53

0.68

0

671

289

Mol wt

A n a l y s i s of c e n t r i f u g e d l i q u i d product (CLP) from run FB-38, batch 7 ( 4 1 5 ° C, 4,000 p s i ) . V i s c o s i t y of CLP; 85.6 SSF at 1 8 0 ° F

Pet of Total product

TABLE V I . -

1

53 at 100° F

Viscosity


In Hydrocracking and Hydrotreating; Ward, J., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1975. C 88.52

89.03 86.80

75.2

22.3

1.8

0.7

Oil

Asphaltenes

Pyridine solubles

Pyridine Insolubles

1

In centistokes

Fraction

Pet of total product

4.75

6.13

8.89

2.63

2.10

0.83

0.46

0.27

0.23

28.5

2.29

0.0

0.0

U l t i m a t e a n a l y s i s , v t pet H Ν S Ash

459

0.82

2.47 3.07

227

Mol wt

1.20

H/C

1.53

0

A n a l y s i s of c e n t r i f u p e d l i q u i d product (CLP) from run FB-40, batch 7 (450° C, 2,000 p s i ) . V i s c o s i t y of CLP: 58.9 c e n t i s t o k e s at 140° F, 14.3 SSF at 180°

TABLE VII.F

1

e

11.8 140

at F

V i s cosity


ο

°


3.3

Pyridine insolubles

In c e n t i s t o k e s

4.39

73.06

4.8

Pyridine solubles

1

6.27

87.33

40.2

Asphaltenes

8.49

0.0

0.62 1.41 14.28

2.14 2.32

65.5

0.0

0.42

1.10

4.54

3.64

2.42

Ultimate a n a l y s i s , wt pet H Ν 0 S Ash

87.57

C

51.7

total product

Oil

Fraction

___

0.72

0.86

1.16

H/C

417

225

Mol wt

1

16.5 at 140° F

V i s cosity

A n a l y s i s o f c e n t r i f u g e d l i q u i d product (CLP) from run FB-40, batch 88 (450° C, 2,000 p s i T T V i s c o s i t y o f CLP; 1,433 c e n t i s t o k e s a t 140° F, 97.6 SSF a t 180° F

TABLE V I I I . -


3

2. *a

si

>-

CO ο 40 CO

CO 200

>

H

3

to >

100

3

çP . 16

20

L_

_L_ 10

22

24

26 I 15

28

30

32

_JL_ - J 20

ASPHALTENES .percent

Figure 4. Viscosity of CLP vs. asphaltene content


122

HYDROCRACKING AND HYDROTREATTNG

Literature Cited 1.


2.

3.

Akhtar, Sayeed, Lacey, James J., Weintraub, Murray, Reznik, Alan Α., and Yavorsky, Paul M. The SYNTHOIL Process--Material Balance and Thermal Efficiency. Presented at the 67th Annual AIChE Meeting, December 1-5, 1974, Washington, D.C. Akhtar, Sayeed, Mazzocco, Nestor J., Weintraub, Murray, and Yavorsky, Paul M. SYNTHOIL Process for Converting Coal to Nonpolluting Fuel Oil. Presented at the 4th Synthetic Fuels from Coal Conference of the Oklahoma State University, Stillwater, Oklahoma, May 6-7, 1974. Yavorsky, Paul Μ., Akhtar, Sayeed, and Friedman, Sam. Process Developments: Fixed-Bed Catalysis of Coal to Fuel O i l . AIChE Symposium Series, v. 70, No. 137, pp. 101-105, 1974.


Hydrocracking and Hydrotreating

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