Proposal for Urea

1Urea plant design proposal through Snamprogetti process

Proposal for Urea (Snamprogetti process) plant design

By

Adil Amin

PG-E10-08

XYZ design firm

Institute of Chemical Engineering and Technology, University of the Punjab

Professor Dr.Mahmood Saleem

Assigned: January 17, 2014

Due: January 24, 2014

Submitted: January 24, 2014

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Table of contents

Executive summary……………………………………………………………. 4

Proposal basis……………………………………………………………………..7

Proposed technology…………………………………………………………..9

Major equipment data sheet………………………………………………17

Technical and economic assessment…………………………………..20

Qualification and experience of project

Higher personnel ……………………………………………………………...21

Project schedule………………………………………………………………..22-23

Conclusion………………………………………………………………………… 23

Contact details…………………………………………………………………..24


1. Executive summary

This proposal is in the response of the invitations from Institute of chemical engineering and technology for the design and installation of urea plant with energy efficient process. We XYZ firm are willing to do this great project. XYZ firm is well established and recognized firm. We provide excellent work.

XYZ firm has proposed urea plant design using snamprogetti process. Snamprogetti process is well known modern technology, which is meeting modern day demands. Snamprogetti process is energy efficient and gives good quality urea production with very minimum energy wastage. Almost many of the world’s urea production companies have switched to or have installed expansion plants after inspiring with this technology. Fauji Fertilizer, Goth machhi, Industry is presently running on this technology. This company is the best urea producing company of the Pakistan.

Snamprogetti process for urea production is by reacting

liquid ammonia & gaseous carbon dioxide, which was first introduced in

Germany in 1922. The two reactants react in urea reactor under high

temperature & pressure. The reaction proceeds in two steps, 1st step is

formation of an intermediate product ammonium-carbamate. In 2nd

step it dehydrates to form urea & water.

2NH3 + CO2 NH2COONH4 H = - 37.6 KCal


NH2COONH4 NH2CONH2 + H2O H = + 6.3 KCal.

(Urea)

First reaction is highly exothermic, fast & immediately goes to

completion. The second reaction is endothermic & is only partially

complete. The unconverted ammonium carbamate is then decomposed

back into ammonia & carbon-dioxide & totally recycled back to urea

reactor. The design efficiency of most urea reactors is between 60 to

65%. Block diagram of the process is given below.

The detailed description of the process, total production, cost of

production and project scheduling detail is present in this proposal.XYZ

firm provides assurance of the project completion on the given time

scale.


2. Proposal basis

2.1. Statement of proposal

Our firm XYZ has proposed urea production according to snamprogetti process for your new plant. The purpose of choosing (Snamprogetti process) plant design is to make use of new efficient technology, which improves urea quality, and reduce production cost.

2.2. Feed Stocks

The required feedstocks for the urea production are Carbon dioxide and Liquid Ammonia. The feedstocks, which your company ABC is producing, are meeting our design requirement. This is very good sign. For you convenience the feedstock’s specifications along with the required utilities mentioned below.

Ammonia (Liquid)

Battery Limit Conditions:

Pressure :24 kg/cm2(g)

Temperature :29˚C

Ammonia : 99.8 %wt mm.

Oil : 5 ppm max.

Water : 0.2 %wt max

Carbon Dioxide (Gas)

Battery Limit Conditions:


Pressure : 0.2 kg/cm2 (g) mm.

Temperature : 60˚C

CO2 : 99.7 % vol.

Water : Saturated

H 2+ N2+ CH4 : 0.23 %vol.

UTILITIES

Steam

Power

Cooling Water

Instrument Air/ Utility Air

Inert Gas (Nitrogen)

2.3. Product specifications by the proposed process (Snamprogetti)

This product specification chart is currently followed in a well known urea producing company ‘’Fauji fertilizer company at Goth Machhi’’.


This company is also using the same proposed Snamprogetti process for producing urea at minimum cost as compared to other processes.

2.4. Why Snamprogetti process is better than Stamicarbon process

This above comparison concluded that proposed snamprogetti is far better than stamicarbon process in term of energy efficiency, production cost and product quality.


3. Proposed Technology

3.1. Process description

Description of Snamprogetti Urea Process

Main stages of the process are:

a) CO2 compression b) Urea synthesis and high pressure recoveryc) Medium pressure recoveryd) Low pressure recovery e) Urea solution concentration f) Prilling g) Waste water treatment

a) CO2 Compression

Urea synthesis takes place at 154 ATA and 175oC. CO2 is available at 0.3 Ata at battery limit, therefore the CO2 gas available from ammonia plant has to be compressed to a synthesis pressure for feeding into the urea reactor.

The compression is done in the four stage centrifugal compressor driven by Extraction steam turbine.

A four stage reciprocating compressor was added in 1993 to meet the additional requirement under debottlenecking.

b) Urea Synthesis and High Pressure Recovery


Urea is produced by synthesis from liquid ammonia and gaseous carbon dioxide. In urea reactor (57 % efficiency), R-101, liquid ammonia and carbon dioxide react to form ammonium carbamate, a portion of which dehydrates to form urea and water. The reactions are as follows:

2NH3 + CO2 NH2 COONH4 (ΔH = -100KJ/Mole)

NH2COONH4 NH2 CONH2 + H2O (ΔH = -100KJ/Mole)

Optimum temperature and pressure for synthesis are 188oC and155 Ata respectively. The first reaction occurs rapidly and is completed; the second reaction occurs slowly and determines the reactor volume.

The fraction of ammonium carbamate that dehydrates is determined by the ratio of the reactants, the operating temperature and the residence time in the reactor.

Optimum range of molar ratio of ammonia to carbon dioxide is 3.2-3.5 to 1 and molar ratio of water to carbon dioxide is 0.50-0.70 to 1.0.

The liquid ammonia coming directly from the battery limits is collected in the ammonia receiver, V-101. From where the ammonia is pumped to the high pressure section using ammonia booster pumps, P-105A/B and high pressure reciprocating ammonia feed pumps, P-101A/B/C.

High pressure liquid ammonia is used as driving fluid for the carbamate ejector EJ-101, which is used to transfer carbamate to the reactor coming from carbamate separator, MV-101.

From CO2 compressors K-101 & K-101A the carbon dioxide received at 156Ata and enters into urea reactor R-101. A small quantity of air is introduced in the suction of K-101 (in future it will be introduced in 1st stage discharge), in order to passivate the stainless steel surface of the equipments, thus protecting them from corrosion.

The reaction products leaving the reactor enters in falling film stripper, E-101. The mixture is heated as it flows down the falling film exchanger. The carbon dioxide content of the solution is reduced by the stripping action of the excessive ammonia as it boils out of the solution and as well as by mass transfer phenomenon. Heat for the decomposition of carbamate is supplied by saturated steam at 26Ata and 225°C.


The overhead gases from the stripper and recovered carbonate solution from the medium pressure section is routed to the carbamate condenser, E-105A/B where the total mixture, except for a few inerts, is condensed and recycled to the reactor by means of carbamate ejector, EJ-101.

Condensing the gases at high pressure and temperature permits the production of steam at 3.5 kg/cm2g in the shell side of carbamate condenser, E-105A/B.

The incondensable gases from the top of the carbamate separator MV-101 consist mainly of inert gas, with a small quantity of NH3 and CO2, are passed under pressure control to the MP decomposer holder, ME-102.

c) Medium Pressure Recovery Section

The solution, with a low residual CO2 content, leaving the bottom of the stripper, E-101 is expanded at 17Ata pressure and enters in MP decomposer, E-102A/B through MP Pre-decomposer E-102C.

MP decomposer is divided into two parts:

1. MP decomposer separator MV-102; where the released flash gases are removed before the solution enters the tube bundle of E-102A/B.

2. Decomposition section E-102A/B; where the residual carbamate is decomposed and the required heat is supplied by means of steam condensate at 20Ata and 215oC (in the upper part of E-102A shell) and saturated steam at 25Ata and 220oC (in lower part of E-102B shell).

The NH3 and CO2 rich gases leaving the MP decomposer top separator, MV-102 are sent to the shell side of vacuum Pre-concentrator, E-150 where they are partially absorbed in the aqueous carbonate solution coming from the LP section. The heat of absorption and condensation is used in evaporating water from urea solution flowing in the tube side.

The final condensation of the vapors takes place in MP Condenser, E-107 where the residual heat of absorption and condensation is removed by tempered water. The


mixed phase from E-107 flows to the MP absorber, C-101 where absorption of CO2

and rectification of ammonia takes place. Pure ammonia is used as a reflux which is drawn from the ammonia booster pump, P-105A/B.

The bottom solution from C-101 is recycled by High pressure carbamate solution pumps, P-102A/B to the high pressure section.

The ammonia vapors with inert gases coming out from the top of MP absorber, C-101 are partially condensed by cooling water in the ammonia condenser, E-110. From here the liquid and gaseous phases are sent to the ammonia receiver, V-101.

From ammonia receiver, V-101 the inert gases saturated with ammonia enter in the ammonia pre-heater for heating battery limit ammonia, and then sent to the MP falling film ammonia absorber, E-111 where ammonia is absorbed in cold steam condensate coming from the MP inerts washing tower C-103.The heat of absorption is removed by cooling water in the shell side. From the bottom of E-111 the ammonia solution is recycled to the medium pressure absorber, C-101 by means of the ammonia solution pumps, P-107A/B.

The upper part of the MP Inert washing tower, C-103 inert gases are submitted to a final washing by means of the cold steam condensate. Inerts sent to the blow down system under pressure control.

d) Low Pressure Recovery Section

The solution leaving the bottom of MP decomposer holder, ME-102 is expanded at 3.5 kg/cm2g pressure and enters in LP decomposer, E-103 which is divided into two parts:

1. LP decomposer separator MV-103, where the released flash gases are removed before the solution enters the tube bundle.

2. Decomposition section E-103, where the residual carbamate is decomposed and the required heat is supplied by mean of saturated steam at 4.5Ata and 147oC.

The gases leaving the top LP decomposer separator, MV-103 jointly with ammonical solution from the waste water treatment section are sent to the LP condenser, E-108 where the heat of absorption and condensation is removed by cooling water.


The liquid phase, with the remaining inert gases, is sent to the carbonate solution accumulator, V-103. From here by means of the MP carbonate solution pumps, P-103A/B, the carbonate solution is recycled back to MP section

The inert gases are washed in the LP inert washing tower C-104 with cold steam condensate and then sent to blow down system.

e) Urea Concentration Section

In order to prill urea, vacuum concentration section is provided to concentrate the urea solution up to 99.7% wt.

The solution leaving the bottom of LP decomposer holder, ME-103 is expanded at 0.45Ata and enters in the vacuum pre-concentrator, E-150 which is divided into two parts:

1. vacuum pre-concentrator separator, MV-150 where the released flash gases are removed before the solution enters the tube bundle:

2. Decomposition section E-150, where the last residual carbamate is decomposed.

The gases leaving the top of the pre-concentrator, MV-150 are routed to the vacuum unit where condensation takes place.

The urea solution collected at the bottom of the vacuum pre-concentrator holder ME-150 is sent to the 1st vacuum concentrator, E-114 by the urea solution pumps, P-150A/B. Operating pressure of E-114 is 0.45 Ata, and heat is supplied by steam at 4.5Ata and 147oC for evaporation of water.

The mixed phase coming out of E-114 enters in 1st vacuum separator, MV-106 where vapors are extracted by the vacuum system, while the solution concentrated up to about 95% wt. enters in 2nd vacuum concentrator, E-115. Operating pressure of E-115 is 0.045 Ata, and heat is supplied by steam at 6Ata and 160 oC for evaporation of water.

The mixed phase coming out of E-115 under temperature control enters the 2nd

vacuum separator MV-107 from where vapors are extracted by the vacuum system while the melted urea (99.7% wt) at temperature of about 140oC reaches the 2nd

vacuum separator holder, ME-107.


f) Prilling

The melted urea leaving the 2nd vacuum separator holder, ME-107 is sent to the prilling bucket, ME-109A/B by means of the melt urea pump, P-108A/B.

The urea coming out of the bucket in the form of drops falls along the prilling tower and encounters a cold air flow which causes its solidification.

The solid prills falling at the bottom of the prilling tower are sent to bagging section for shipment by means of urea conveyor belts.

g) Waste Water Recovery

The waste water collected from vacuum section is treated to hydrolyze urea into ammonia and CO2 and then recycle back recovered CO2 and ammonia to LP recovery section.

Waste water is fed into the column, C-102 after preheating with the outgoing waste water. Low-pressure steam is introduced in the column for stripping. Feed from the middle of the column is taken and sent to the hydrolyser, R-102 that operates at 36 Ata & 235oC. The hydrolyzed solution is taken back into the column.

Vapors from the hydrolyser are combined with the vapors from the column top and condensed in the condenser, E-117. The uncondensed gases / inert are vented while the solution from the condenser is collected in the accumulator and recycled to the LP recovery section by means of pump, P-115. Treated water sent to evaporation pond by means of pump, P-114.

Process flow diagram for the whole process has been attached in the proposal documents.

3.2. Reactor selection

The ‘’Plug flow reactor containing sieve trays’’ is selected for the urea production. Carbon dioxide and ammonia comes into the


reactor where they react to form urea. This type of reactor is selected because it gives maximum conversion of feed into urea solution.

Reactor is equipped with 10 sieve trays in the upper part of the reactor. Sieve trays holes having diameter of 8mm are equally spaced on the trays surface. The function of trays is to prevent escape of gaseous CO2, which must react in the lower part of the reactor with ammonia and prevent internal recycling of reaction product as higher density products formed as reactants move upward in the reactor. The volume and holding time of reactor is designed to allow the carbamate conversion into urea and water.

3.3. Major Equipments

Equipment List:

Urea Reactor, R-101

HP Ammonia Pumps , P-101A/B/C

High Pressure Carbamate Solution Pumps, P-102A/B

Urea Stripper, E-101

Carbamate Condensers, E-105A/B

Carbamate Separator, MV-101

Carbamate Ejector, EJ-101

Medium Pressure Decomposer, E-102A/B

Medium pressure condenser , E-107

Medium pressure absorber , C-101

Overhead ammonia condenser , E-110

Ammonia Receiver , V-101

Ammonia booster pumps, P-105 A/B

Ammonia pre-heater, E-109

Medium pressure ammonia absorber, E-111

MP inert washing tower , C-103


LP decomposer , E-103

LP condenser , E-108

Carbonate solution vessel

LP ammonia absorber , E-112

Inert washing tower , C-104

Medium pressure carbonate solution pump P-103 A/B

Distillation tower feed pump , P-106 A/B

Ammonia solution recycle pumps , P-107 A/B

Prilling tower

Note :

Data sheets for main equipment are given on next pages. The data sheet detail about other equipments will be provided to you in basic engineering design report in our first meeting.

Urea Reactor, R-101


High pressure ammonia pumps P-101 A/B/C


Urea Stripper, E-101

Shell Side Tube Side

Fluid circulated Steam Urea solutionNo. of passes 1 1No. of tubes - 2574Tube sheet material - CS+Ti cladding

(Thickness=10mm)Ferrules material - CS+Ti cladding

(Thickness=3mm)No. of ferrules - 2574Packing type - Pall rings

Carbamate Condenser, E-105A/B


Ammonia receiving vessel


4. Technical and economic assessment

This is the cost of sales at FFC. FFC is using the same urea production process, which is proposed to you by us. You can have estimation of the raw material consumption. Highlighted column represents raw material consumption in 2012 and other represents its consumption in 2011.

4.1. Estimated work force requirements (number of operators/shift)


At least 10 operators per shift needed for smooth operation of the plant.

4.2. Total Production

2,610 tonnes/day

4.3. Estimated Cost of production (cost per bag)

Estimated production cost is B rupee per bag .Sales cost is 1700 rupee per bag at, FFC goth machhi, which is producing urea through same proposed process. Sales cost varies according to demand.

4.4. Cost of proposed project

Total project cost rupees

Project installation X rupees

Anticipated annual operation cost Y rupees

Anticipated maintenance cost Z rupees

5. Qualification and experience of project higher personnel

Member Experience

Adil amin B.Sc Chemical engineering

Mr.D Project designer and chief commissioning engineer

Mr.G Product consultant and project engineer

Other team members Well experienced (Have designed and

Installed many plant of this process)

6. Project Schedule


Proposed project designing, construction, Permissions, Installations and performance testing of the completed project are expected to be completed no later than January 31, 2015

Project stage Action required Time and duration

Proposal submitted for interim agreement

Detailed study of different proposals by I.C.E.T.

January ,2014

Execute interim agreement

February,2014

Proposal submitted with GMP for comprehensive agreements

March,2014

Funding and purchasing

Funding should be from investor ,donors and sponsors

April ,2014

Site preparation Facilities provided by investor

May-June 2014

Shipping Shipping, clearing and forwarding of equipment to site

July-august ,2014

Insurance XYZ firm will initially get insured

August , 2014

Fabrication Fabrication of non-shipped equipments

Sep-Oct,2014

Installation Safe installation November-January,2015

Running By the firm XYZ February,2015


Plant handover We will hand over the plant after providing operational training to the personnel’s of the Contractor

March,2015

Project completed By XYZ firm Mrach,2015

The required meetings during the project will be conducted either form you or from us. Any suggestions in the amendment of the schedule are welcome.

7. Conclusion

Urea production through proposed process is much more economical than other processes. It has told you already that Snamprogetti will be the best choice for producing urea as this is a proven technology and is currently applicable in almost all of the plants of the world. This technology ensures energy saving and improved quality of the product. We have passionate team, who love to work. Project will complete on time. Project will be designed according to the International standards. XYZ firm will be responsible for any fault in the equipment designed. We are hopeful to get a positive response from you. Thank you!

Contact details

XYZ firm

123 ABC road, Lahore


+923004149595 , [email protected]

Documents

Proposal for Urea