Case Study: Acetic Acid Recovery from Aqueous Fermentation Broth

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Case Study:Acetic Acid Recovery from

Aqueous Fermentation Broth

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Case Study: Modular System to Recover Acetic Acid from Aqueous Fermentation Broth Stream

KMPS’ engineering team designed a modular acetic acid recovery and purification system as a critical component of a greenfield biomass to renewable chemicals plant. Liquid-liquid extraction, distillation and stripping were the three essential mass transfer processes used in the system. Prior to detailed engineering, the extraction process was tested at KMPS’ Pilot Plant to confirm the conceptual design and allow for an acetic acid recovery and purity Process Performance Guarantee. CLIENT: A Private Biorefining Company

INDUSTRY: Renewable Energy

http://modularprocess.com/pilot-plant-testing/



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Key Engineering Features

Modular design allowed for the customer to concentrate on the balance of the greenfield project’s engineering, infrastructure and on-site construction activities, without interruption.

A Process Performance Guarantee for the system was established through a liquid-liquid extraction pilot test.

The selected solvent for the extraction was one produced on site in a separate process, and the system was designed such that solvent losses were minimized.

The system was designed to accommodate a broad range of acetic acid feed concentrations.

A complete control system was provided that afforded robust control of the process and included alarms and interlocks for safe operation.

KARR® Column



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Core Challenges

Processing of an Aqueous Fermentation Broth:bio-derived aqueous streams have a tendency to emulsify with solvents in liquid-liquid extraction columns. The customer had observed the aqueous feed forming an emulsion with solvents during their laboratory testing, and were extremely concerned that this could impact the commercialization of the process.

Multiple feed compositions and turndown requirements were evaluated during development of the Process Performance Guarantee.

Materials of construction - concentrated acids posed significant corrosion and safety concerns.

Layout – accessibility of equipment and instrumentation for maintenance in a compact area.

Installation – ensure that the installation of the modules and extraction column internals did not disrupt the other engineering and operating activities taking place at the site.

An azeotrope refers to when a mixture boils at constant temperature without a change in composition. In this case, the azeotrope did not need to be exceeded so conventional distillation could be used. However, because of the converging nature of the vapor-liquid equilibrium curve or “pinch,” activity coefficients needed to be carefully selected so that an accurate number of required theoretical stages was predicted and the equipment could be designed properly.Installation of KARR® plate stack at plant site



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Typical Biomass to Renewable Chemicals Fermentation Process Block Flow Schematic

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Fermentation

Additional Dist.Product(s) Purification

Distillation (Solvent Recovery)

Broth TreatmentFiltration

CentrifugeCell Disruption

Liquid-Liquid ExtractionSolvent Stripping

Recycle Solvent

Spent Broth Recycle

Solvent

Extract



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Recovery of Acetic Acid from FermentationBroth Using a Low Boiling Solvent

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Fermentation Broth

Acetic Acid

Extraction

Raffinate

Stripping

Solvent Recovery

Raffinate

RecycledSolvent

Extract

RecoveredAcetic AcidWaste Water



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The Solution

KMPS was awarded this project due to a successful pilot test which proved that KMPS’ extraction technology could process the feed material and meet the customer’s recovery specifications. The pilot test was performed using a KARR® Column – a KMPS proprietary liquid-liquid extraction technology - and enabled KMPS to provide the customer with a Process Performance Guarantee based on provided production rates. KARR® columns, due to the reciprocating action of the plate stack (internals), are best suited for systems that have the potential to emulsify. KMPS’ vast experience in solvent recovery mass transfer processes gave the customer additional confidence in the conceptual design that was proposed. Once the pilot test was complete, KMPS developed a simulation to model the complete process. Vapor-liquid equilibrium (VLE) data for the solvent recovery area was based on past project experience and liquid-liquid equilibrium data (LLE) was selected based on the analysis of pilot test runs. The simulation served as the basis of design for all the major process equipment.

R1R2R3

R4

E1 E2 E3E4

M1M2M3M4

B

A C

F

Ternary LLE phase diagram



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The Solution – Cont’d

KMPS supplied a process design package to the customer, and once approved moved onto detailed engineering and procurement. PFD’s & P&ID’s were developed and the modules were designed using 3D CAD software. Equipment was designed and purchased, and instruments were specified. A control system complete with a PLC, I/O modules, control panel and HMI was designed and programmed to the customer’s specifications. PLC was integrated into the overall plant DCS. A customer led HAZOP review was performed and then necessary alarms and safety interlocks were implemented into the control system.



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A key design feature in the recovery area made use of a vapor side draw to separate the recovered acetic acid from a less volatile acid in the bottom of the solvent recovery column, enabling the system to meet the customer’s product purity specification and minimize the required processing equipment. Also, to address potential corrosion concerns, KMPS suggested using Alloy 2205 stainless steel for equipment and piping where acetic and sulfuric acid were concentrated.

Prior to modular assembly, the customer participated in a “walk-through” of the module’s equipment layout and piping using a 3D model generated by CAD software. This allowed the customer to become more acclimated with the modules prior to installation, and allowed KMPS to ensure that all equipment and instrumentation were accessible.

While the modules were being assembled, KMPS provided the client with information to prepare the jobsite for delivery. KMPS supplied foundation loads, anchor bolt patterns, piping tie-in coordinates, and electrical drawings. Performing these site activities ahead of module delivery greatly streamlined and shortened the installation process. After the modules were delivered KMPS supervised the installation of the modules and the KARR® column plate stack and drive, and provided commissioning and startup support.



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The finalized design included the following:

(2) Process modules (Each approx. 11’6” x 14’ x 60’)

o (1) KARR® LLE column (22” ID x 51’ T/T)

o (1) Solvent recovery column(34“ ID x 43’ T/T)

o (1) Waste water stripper(8“ ID x 19‘ T/T)

o (4) Vesselso (7) Heat exchangers o (4) Mag drive centrifugal pumps



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Impact

KMPS designed, constructed and delivered an acetic acid recovery system critical to the success of the customer’s greenfield plant and overall process. The modules were delivered to the site 34 weeks after detailed engineering began.

KMPS’ solvent recovery experience, liquid-liquid extraction technology, and upfront pilot testing resulted in a modular system that was successfully started up and met all performance specifications.

Modular construction allowed KMPS to design and construct the system off site, allowing the customer to focus on up and downstream process engineering, infrastructure and other balance of plant activities while also reducing schedule, cost, and their overall man-power requirements.



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Why Modular from KMPS?

For this project, KMPS leveraged its Pilot Plant capabilities, proprietary extraction technology, and experience designing solvent recovery systems which resulted in a complete Modular Acetic Acid Recovery system that was supplied with a Process Performance Guarantee. Our modular fabrication approach to process systems has many advantages, the main points of which are highlighted below. To learn specifically how modular fabrication achieves these benefits, please visit our website: www.modularprocess.com

Shorter schedule / faster time to market

Lower cost / lump sum bid / single source

Minimal plant site interruption / improved safety

http://www.modularprocess.com/



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KMPS Products & Services

Customer Inquiry Data

Startup Assistance and Training

Process Development (In Collaboration with Client’s Engineers

and Scientists)

Material Balance, PFD’s, Unit Operation Selection, Process Simulation

Process DesignEquipment Design, P&ID’s, Equipment

General Arrangement

Detailed EngineeringEquipment, Piping, Structural,

Electrical, Instrumentation & Controls

ConstructionModular System

Specialists in Process Design and Construction of Modular Mass Transfer Systems for the Chemical Processing Industry.

Pilot Plant Testing(If Required)

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Case Study: Acetic Acid Recovery from Aqueous Fermentation Broth

Brendan Cross | Process Engineerwww.linkedin.com/in/brendancross

Brendan has over 10 years of experience on chemical separation processes, including: continuous and batch processes involving distillation, liquid-liquid extraction, stripping and absorption. Brendan has a BS in Chemical Engineering from Columbia University.

http://www.linkedin.com/in/brendancross