Production of Ethanol by Gavin Chen

1. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 1 of 15

Production of Ethanol with Corn
Using Dry Milling Method

Section Page Number
Block Flow Diagram pg 2
Process Flow Diagram pg 3
Biological Pathway & Chemical Reactions pg 5
Mass and Energy Balance pg 6
Sizing a CSTR Fermenter pg 8
Piping and Instrumentation Diagram pg 9
Characterization of Streams pg 10
Hazard and Operability Study pg 11
Capital Expenditure pg 12
Operation Expenditure pg 13
Reference pg 15

Dec. 20
th
2016
By Gavin Chen

2. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 2 of 15
Block Flow Diagram

The Dry Mill Process will happen in 4 basic steps
The first process is the preprocessing process. In this step, the dry corn feedstock would be
mashed into smaller particle sizes. Then the dry corn feedstock would be treated with fresh water
for hydrolysis process.
The second process is the liquefaction and the saccharification process. The hydrolyzed corn
feedstock would be treated with hot steam through jet cooker. In the liquefaction step, the
enzyme, Alpha Amylase, is added to perform saccharification for converting corn into glucose
slurry.
The third process is the fermentation process. The purpose of fermentation is to convert glucose
slurry to alcohol slurry. Gluco Amylase and yeast are required for this process. The residence
time of the glucose slurry should be between 50 to 60 hours, and it is determined to be 60 hours
for maximum conversion.
The forth process is the purification process. The alcohol slurry would be transferred to a
distillation column. The desired ethanol would be vaporized to the overhead of the column.
Then, the ethanol-water azeotrope would be further purify. The co-product, DDGS, would be
dried and put to a storage.

3. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 3 of 15
Process Flow Diagram

This process begins by breaking the dry corn feedstock from the storage tank (TK-110) into
smaller particle sizes through the Hammer Mill (V-410). Then the dry corn would be mixed with
fresh water(TK-120) to perform hydrolysis in the cyclone (TK-130).
The second step involves liquefaction and saccharification. The corn slurry from cyclone (TK-
130) would be transferred and heated through a steam jet cooker (E-210). This process
approximately takes about 30 to 40 minutes and the slurry is heated to 70 degrees C. Then, the
corn slurry is transferred to the liquefaction reactor (R-510) in order to convert corn slurry to
glucose slurry. The required enzyme, Alpha Amylase, would be added from the tank (TK-140).
The liquefaction process performs at the temperature between 85 to 95 degrees C. After the
liquefaction process, the glucose slurry would be discharged into a knock-out drum (E-220) for
the mash cooling process. When the temperature of the glucose slurry drops to 32 degrees C, the
glucose slurry would be ready for the fermentation process.
In the fermentation process (R-520), the entire process takes 60 hours for converting glucose
slurry to alcohol slurry with the maximum yield.
After the fermentation process, the next stage is the purification process. The alcohol slurry
would be transferred to the distillation column (T-310). The desired ethanol-water azeotrope
would be separated out in the overhead of the column through vaporization. The desired pure
ethanol product would be stored in the tank (TK-160). The remaining slurry would be discharged
from the bottom of the column. The ethanol-water azeotrope would be purified again through

4. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 4 of 15
molecular sieves (T-320&T-330) for extracting out the majority of the water component. The
remaining slurry would be transferred to the knock-out drum (V-430) through the centrifuge (V-
420). After the slurry gets dried, the DDGS would be stored in the cyclone (TK-170).

5. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 5 of 15
Biological Pathway
This report discusses the Dry Milling Method to produce Ethanol.
The process begins by adding process water to the milled corn grains, adjusting the pH to about
6, and adding a thermostable Alpha Amylase. The following step is starch liquefaction. After the
dry corn feedstock gets converted into glucose slurry by using thermal and pressure energy, the
glucose slurry gets transferred into the reactor for fermentation. While fermenting, the yeast,
Saccharomyces Cerevisiae, is added for ethanol production. The main reaction in the
fermentation stage is given as
�
6�
12�
6+2�??????+2??????�� →2�
2�
5��+2��
2+2??????��+2�
2�
������� →2 ��ℎ����+2 ������ �??????��??????��+������

The theoretical yield is 0.511 � ethanol produced per gram glucose consumed. According to our
references and the adjustments due to the current market, the conversion factor of kg ethanol
produced per kg dry corn consumed is 0.3104. Our basis of corn feedstock is 1,000,000 metric
tons of corn feedstock which contains 85% dry corn and 15% moisture.
The following report discusses the process design of ethanol production starting with 1,000,000
metric tons of feedstock per hour as the initial mass flow rate to begin with.

6. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 6 of 15
Mass and Energy Balance

The theoretical yield of ethanol from starch:
(�
6�
10�
5)
�+�
2�→�
6�
12�
6→2�
2�
5��+2��
2
Assumptions:
�����ℎ(��)= 0.6 �������(��)
90% ethanol yield
??????����=0.0008(������� ������)
??????��ℎ� ??????������ = 0.0001(��� ����)
�
??????���� = 172 �/���
Basis:
1,000,000
����??????� ���
����
���� ��������� �??????�ℎ 15% ��??????�����
1,000,000
����??????� ���
����

1.10231 ���
����??????� ���

2000 ��
���

����
330 ���

���
24 ℎ�
=280,000
��
ℎ�
���� ���������
280,000
��
ℎ�
����∗(0.85)=240,000
��
ℎ�
��� ����
240,000
��
ℎ�
��� ���� (0.617)=150,000
��
ℎ�
�����ℎ=68,000
��
ℎ
�����ℎ
=380
����
ℎ
�����ℎ
Based on the stoichiometry:
380
����
ℎ
�����ℎ + 380
����
ℎ
??????����→380 ????????????
����
ℎ
�������
→2(380
����
ℎ
��ℎ����)+2(380
����
ℎ
��
2)

7. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 7 of 15
Amount of water used in fermentation:
380
����
ℎ
�����=6,900
��
ℎ
�����=15,000
��
ℎ
�����=30 ��� �����
Theoretical yield of glucose:
380 ����
�������
ℎ�
= 69,000
��
ℎ�
�������=150,000
��
ℎ�
�������
Theoretical yield of ethanol and CO2:
2(380
����
ℎ
��ℎ����)=760
����
ℎ�
��ℎ����=35,000
��
ℎ
��ℎ����=77,000
��
ℎ�
��ℎ����
=195 ��� ��ℎ����
2(380
����
ℎ�
��
2)=760
����
ℎ�
��
2=34,000
��
ℎ�
��
2=74,000
��
ℎ�
��
2
Alpha Amylase Calculation:
0.0001(280,000
��
ℎ�
��� ����)=28
��
ℎ�
??????��ℎ� ??????������
Yeast Calculation:
0.0008(28
��
ℎ�
??????��ℎ� �������+150,000
��
ℎ�
�������+15,000
��
ℎ�
�����)=140
��
ℎ�
�����

Theoretical Yield of Ethanol:
0.90(77,000
��
ℎ�
)=69,000
��
ℎ�
��ℎ����=180 ��� ��ℎ����
Amount of water outlet:
15,000
��
ℎ�
�����−(0.90∗15,000
��
ℎ�
�����)=1,500
��
ℎ�
�����=3 ��� �����
Amount of glucose outlet:
150,000
��
ℎ�
�������−(0.90∗150,000
��
ℎ�
�������)=15,000
��
ℎ�
�������
Total amount of beer slurry:
69,000
�� ��ℎ����
ℎ�
+15,000
�� �����
ℎ�
+150,000
�� �������
ℎ�
+28
�� ���ℎ� �������
ℎ�
+140
�� �����
ℎ�
≈230,000
��
ℎ�
���� ������

8. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 8 of 15
Sizing a CSTR Fermenter
Calculations of Alcohol Slurry out of Fermenter
150,000
�� �������
ℎ�

��
2.205
=68,000
�� �������
ℎ�

�
3
1540 �� �������
= 44
�
3
ℎ�
�������
1,500
�� ??????����
ℎ�

��
2.205
=680
�� ??????����
ℎ�

�
3
1000 �� �������
=0.68
�
3
ℎ�
�����
69,000
�� ��ℎ����
ℎ�

��
2.205
=32,000
�� ��ℎ����
ℎ�

�
3
789 �� ��ℎ����
=40
�
3
ℎ�
��ℎ����
Total Mass of Beer
68,000
�� �������
ℎ�
+ 680
�� ??????����
ℎ�
+ 32,000
�� ��ℎ����
ℎ�
= 100,000
�� ���� �����??????
ℎ�

Total Volumetric Flow Rate
4
�
3
ℎ�
�������+ 0.68
�
3
ℎ�
�����+ 40
�
3
ℎ�
������� = 45
�
3
ℎ�
���� ������
Density of Beer Slurry
100,000
�� ���� ������
ℎ�

ℎ�
45 �
3
=2254
��
�
3
���� ������
GPM Flow Rate of Beer Slurry
100,000
�� ���� �����??????
ℎ�

�
3
2254 �� ���� �����??????
264
���
�??????�

ℎ�
60 �??????�
= 197 gpm beer slurry
Total Capacity needed for 60 hours Residence Time
197
������ ����?????? �����??????
�??????�
60
�??????�
ℎ�
60 ℎ� ���??????����� �??????�� = 707,843 gallons of beer
slurry_out
707,843 gallons
# �� ���� ����������
15,000 �������
~ 47 ���� ����������

9. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 9 of 15
Piping and Instrumentation Diagram

This is the P&ID of R-520 Fermenter. Overall, there are 4 loops for monitoring this fermenter.

In Loop 1, we are detecting the flow rate of glucose slurry going in.

In Loop 2, we are detecting the temperature of steam stream going into the jacket in order to
control the flow of steam and to adjust the flow of condensate.

In Loop 3, we are detecting the pressure of the CO2 gas product coming out from the fermenter.

In Loop 4, we are detecting the leveling control in order to adjust the flow of the product stream
going out from the fermenter.

For the inlet and the outlet streams, 7” Schedule 40 Stainless Steel pipes are used for transferring
the glucose slurry and the alcohol slurry.

For the gas product stream, 4” Schedule 40 Stainless Steel pipe is used.

For the steam streams, 4” Schedule 40 Stainless Steel pipes are used for the incoming steam and
and the outgoing condensate.

10. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 10 of 15
Characterization of Streams


These testing methods have been taken from ASTM method. ASTM standards are used world
wide to improve product quality, enhance safety.
D887 (11.02) is a practice used for sampling water-formed deposits.
E1758 (11.06) is test method for determination of carbohydrates in biomass by HPLC.
D3048 (15.04) is test method for enzymes assay
E346 (15.05) is test method for analysis of ethanol

11. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 11 of 15
Hazard and Operability Study

If reactor temperature is too high, set parameters. Fouled or failed exchanger tubes. Fire
situation. Defective control valve. Internal Fires. Heating fluid/medium leaking. Faulty
instrumentation and control.
If higher pressure inside reactor happens, Surge problems for pump stop/starting or valve turning
on/off. Relief valve isolated. Thermal overpressure. Boiling. Worst case, explosion.
If reaching high level in reactor, reactor outlet blocked or isolated. Inflow greater than outflow.
Faulty level measurement. Pressure surges for sudden change in the velocity of the fluids; caused
by pump starting/stopping or valve opening/closing.
If power outage happens, lightning, high winds, ice storms. Accidents at power plants and
transmission lines.

12. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 12 of 15
Capital Expenditure

13. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 13 of 15
Operation Expenditure

In the Operation Expenditure, we are estimating the overall costs of the entire operation of our
Dry Milling Ethanol plant.
The basis of the feedstock is 280,000
�� ��?????? ����
ℎ�
. As the kg-ethanol-to-kg-corn conversion factor
given in the textbook, Biofuels Engineering Process Technology by C. Drapcho, N. Nhuan, and
T. Walker, being applied, the annual production of ethanol is estimated to be 90,000,000
������� ��ℎ����
??????���
. According to the price of ethanol from Nasdaq.com, one gallon of ethanol is sold
for $1.80 USD. As result, the estimated annual revenue comes out to be around $162 million
USD.
The operating cost of steam is the major component in our budget. It takes 8 million dollars for
having 330,000 lb/hr steam in supporting each of the 47 fermenters we have and 1 reactor for
liquification over a year. The price of steam varies from
$2 ���
1000 �� �����
to
$3 ���
1000 �� �����
.
Unit cost of enzymes is respectively high comparing to others. The costs of enzymes include the
cost of Alpha Amylase in liquefaction, and the cost Glu Amylase in fermentation.
The cost of maintenance is 5% of the CapEx.
For the labor distribution, we plan to have 42 operators alternating 3 shifts a day. 14 engineers
doing safety check, 14 engineers doing maintenance, and 7 operating manager.
Due to the annual revenue, $162 millions USD, the operating cost, $155 millions USD, and the
capital cost, $17 millions, can be balanced off as a result of having positive $8 million USD.
The profit in 1
st
is estimated to be $7 millions USD.

14. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 14 of 15
Operation Expenditure-Calculation
BASIS 240,000
�� ��?????? ����
ℎ�

Annual Ethanol Production
240,000
�� ��?????? ����
ℎ�

��
2.205 ��

0.3104 �� ��ℎ����
�� ��?????? ����

�
3
789��

264.1 ���
�
3

24 ℎ�
��??????

330 ��??????
??????���

= 90,000,000
������ ��ℎ����
??????���

Revenue from Ethanol
90,000,000
��� ��ℎ����
??????���

$ 1.80 ���
������ ��ℎ����
=$162,000,000 ���
Annual Amount of Steam
90,000,000
��� ��ℎ����
??????���

48,000 ��� �����
��� ��ℎ����

�????????????
33479 ���

34.5 ��
�????????????
= 4,500,000,000
�� �����
??????���

Annual Cost of Steam
4,500,000,000
�� �����
����

$3���
1000 �� �����
=$14,000,000 ���
Annual Amount of Corn Feedstock
280,000
�� ���� ���������
ℎ�

24
��??????

330 ��??????
??????���
=2,200,000,000
�� ���� ���������
??????���

Annual Cost of Corn Feedstock
2,200,000,000
�� ���� ���������
����

$0.057 ���
�� ���� ���������
=$126,000,000 ���

15. CHE 199 BIOFUELS FINAL PROJECT Gavin Chen


Production of Ethanol Page 15 of 15
Reference
Alexander, R.J. 1994. Corn Dry Milling: Processes, Products, and Applications. Pages 351 –
371 in: Corn Chemistry and Technology. Watson, S.A. and Ramstad, P.E. eds. American
Association of Cereal Chemist, St. Paul, MN

BBI International, 2003. “The Ethanol Plant Development Handbook,” Edition Four.

Jennifer Lyons and Charles W. White, III. "Process Equipment Cost Estimation Final Report.",
vol. U.S. Department of Energy National Energy Technology Laboratory, no. January 2002,
2002. Thys T. Dale and Wallace E. Tyner. "Economic and Technical Analysis of Ethanol Dry
Milling: Model user’s Manual." Agricultural Economics Department ,Purdue University, no.
Staff Paper # 06-05, 2006.

Jason R. Kwiatkowski ∗, Andrew J. McAloon, Frank Taylor, David B. Johnston. “Modeling the
process and costs of fuel ethanol production
by the corn dry-grind process.” , U.S. Department of Agriculture, Agricultural Research Service,
Eastern Regional Research Center,
600 East Mermaid Lane, Wyndmoor, PA 19038-8598, USA
Received 10 February 2005; accepted 25 August 2005

Musgrove, D., Dale, M.C. 2004. Feasibility Study for an Integrated Grain/Cellulose Ethanol
Plant in Arizona. Report to: USDA, Washington DC, (USDA 02-025-086019322).
Peters, M.S., Timmerhaus, K.D., and West, R.E. 2003. Plant Design and Economics for
Chemical Engineers. McGraw-Hill, New York, NY.

Robert Wooley, Mark Ruth, John Sheehan, and Kelly Ibsen, Henry Majdeski and Adrian Galvez.
"Lignocellulosic Biomass to Ethanol Process Design and Economics Utilizing Co-Current Dilute
Acid Prehydrolysis and Enzymatic Hydrolysis Current and Futuristic Scenario." Technical
Report, no. NREL/TP-580-26157, 1999.

Thys T. Dale and Wallace E. Tyner. "Economic and Technical Analysis of Ethanol Dry Milling:
Model user’s Manual." Agricultural Economics Department ,Purdue University, no. Staff Paper
# 06-05, 2006.