Methanol Technology

7/21/2019 Methanol Technology

1/8

Methanol Technology


2/8

Methanol Process Technology

With some 40 years experience in the methanol business Davy ProcessTechnology is the worlds leading provider of methanol technologies. Morethan 30 plants using these technologies have been built in 16 countriesaccounting for more than 40% of the worlds methanol capacity. DavyProcess Technologys reforming experience and its range of synthesis gastechnologies are key strengths, as is its wide experience with the coremethanol technology from Johnson Matthey Catalysts (previously part of ICI).Since 1985 Davy Process Technology has been responsible for the processdevelopment of approximately 75% of the plants using this technology.

The technology can produce AA grade methanol for chemical applications oralternative grades for olefin production, fuel use or power generation. Wehave licensed technologies for plants with single stream capacities up to 2.4million tonnes per year (6700 tonnes per day) using the Davy ProcessTechnology reactor technology in conjunction with Johnson Mattheys worldrenowned methanol synthesis catalysts and process technology. Designshave also been developed for larger plants for a range of feedstocks.

The Process Options

We offer a wide range of process technologies that can be applied to methanol production. Synthesis gas can be generated by

steam reforming (conventional steam methane reformer or Compact Reformer) or by oxygen reforming (gas heated reforming,combined reforming or auto thermal reforming). Steam or gas cooled reactors are available for methanol synthesis and one,two or three column distillation is used for the production of purified product.

The breadth of technology solutions available to us allows us to custom design a flow sheet to reflect any particular projectsituation, be it large or small, onshore or offshore, for chemical, fuel power generation or MTO use.

Reforming Options Methanol Synthesis OptionsSteam Methane Reforming Each and every methanol loopCompact Reforming is custom designed to provide the optimal

Auto Thermal Reforming (ATR) energy and capital solution for a givenCombined Reforming production capacity and raw gas composition.Gas Heated Reforming

Davy Process Technology supplies technology designs for a wide range of feedstock sources (gas, coal, petroleum coke, etc.)and the type of design matches each clients particular requirements. We custom design every flowsheet from feedstock toproduct specifications to optimise energy and meet capital constraints. This brochure illustrates a range of features of ourmethanol technology and we recommend direct contact with our specialists to determine the solution to match specificrequirements.

M5000 Reformer Trinidad

CRG Pre-Reforming

Reforming

Compression Distillation

MethanolSynthesisLoop

Shift/Sour Shift

Clean UpGasifiedSource

Feed GasClean Up


3/8

Catalyst

Feed gas

Product gas

WaterWater

ProductGas

Inert fill

ProductGas

Steam andwater outlet

Catalyst

Methanol Synthesis

Davy Process Technology together with Johnson Matthey Catalysts is a leadingprovider of methanol technology which is delivered via world class reactor concepts.Here, we describe some of the features of our designs:

Tube Cooled Converter

The tube cooled converter is a simple reactor which uses the feed gas to control thetemperature in the catalyst bed. Fresh feed gas enters at the bottom of the reactor andis preheated as it flows upwards through tubes in the catalyst bed. The heated feedgas leaves the top of the tubes and flows down through the catalyst bed where thereaction takes place.

The heat of reaction is removed by counter-current exchange with feed gas resulting ina temperature profile that approximates to the maximum rate curve. Operated in thismanner the reactor achieves good catalyst utilisation. The internals are relativelysimple having to be designed only for the differential pressure. Tube thicknesses arekept to a minimum and there are no tube sheet construction problems. With thecatalyst on the shell side of the reactor a low cost reactor with an efficient catalystvolume is achieved. As with all axial flow reactors, there is a limit to bed depth due topressure drop constraints. This together with maximum diameters set bymanufacturing or shipping limits means that the maximum capacity possible from asingle reactor is about 2,500 TPD. Above this capacity multiple reactors arerequired.

Radial Flow Steam Raising Converter

This steam raising converter is a radial flow reactor with catalyst contained on theshell side and steam in the tubes. Fresh feed gas enters at the bottom of the reactorthrough a central perforated-wall distributor pipe. The gas then flows radially outthrough the catalyst bed from the inside to out. Water from a steam drum enters atthe bottom of the vessel, and flows upwards through the tubes where it is partiallyvaporised, removing the heat generated by the reaction before returning to the steamdrum. The reaction temperature is controlled by varying the steam pressure insidetubes embedded in the catalyst bed. This arrangement gives an excellenttemperature profile through the catalyst bed minimising the catalyst required.

With a radial flow design the vessel tan to tan height can be increased to maximisethe capacity of the reactor without increasing the reactor diameter or the looppressure drop. Such a concept permits designs for the highest capacity of methanol

production in a single reactor to be achieved with capacities up to 3,500 TPDpossible. This makes the reactor particularly suited to large capacity plants or forlocations where shipping restrictions limit the diameter of the reactor.

Ax ial Flow Catalyst in Tubes

The axial flow catalyst in tube reactor is another form of steam raising converter.As for the radial reactor, the reaction temperature is controlled by varying thesteam pressure. This arrangement gives a good temperature profile through thecatalyst bed minimising the catalyst required and gives efficient heat recovery tosteam. The reactor does however require a thick tube sheets that limits themaximum capacity of the reactor to around 1500 TPD and requires a large numberof tubes to accommodate the catalyst. This tends to make this reactor choice acostly one.

As part of the development of this type of reactor, Davy Process Technologyconstructed both mathematical and physical models and the results over a rangeof conditions were calibrated against real plant tests. Computational FluidDynamics (CFD) is the design tool of choice for a radial-flow converter and aquarter-scale model of a segment of the reactor was built so that the CFD resultscould be compared with water-flow trials. The results were in close comparisonand provided criteria to proceed with sizing of plant designs. Davy ProcessTechnology now uses these proven simulation programmes for new plant designs.


4/8

Synthesis Loop Configuration

Particularly for large plants there is an incentive to increase the conversion in the loop and reduce the loop circulation rate. Thisis exemplified in a Series Synthesis Arrangement as shown below. Our Methanol Technology incorporates a number offlowsheet improvements which give further benefits of larger single stream capacities, lower capital cost, reduced energyconsumption and, longer on-stream periods. The key improvements to the flowsheet can include Catalytic Rich Gas (CRG) pre-reforming technology combined with the Davy Process Technology Steam Raising Reactor in the methanol synthesis loop.These combined features are considered when the feed gas has a significant CO 2content to reduce the size of the radiant box,recover more energy thereby increasing efficiency, reduce the size of the steam system, provide more efficient methanol

synthesis and to reduce the methanol loop operating pressure

Davy Process Technology has no preconceived ideas about the design of large methanol plants. We work with each client toarrive at the optimum solution. We have an entirely original approach to the design of synthesis loops.Particularly for largeplants there is an incentive to increase conversion in the loop and reduce circulation rate. We offer three types of converter:Gas/Tube Cooled, Quench and Steam Raising. These may be used singly or in series and combined with any of our reformertechniques. These reactor options are shown below.

Steam Raising Loop Gas/Tube Cooled Loop Quench Loop

Any of these loop flowsheets may be combined with any of the reforming described elswhere. Moreover it is possible to designcombined reformers with series converters with each unit sized to give the whole flowsheet optimum performance.Consequently, there are many permutations of arrangements and every case is judged on client preferred economics in order todevelop the best process configuration that will deliver the chosen quality of methanol product to market with maximum profit. Asimple Steam Reformer and Gas/Tube Cooled Converter Loop is shown in the flowsheet below.

Steam Reforming w ith Tube Cooled Methanol Converter

Innovative Large Scale Designs

The following example provides an illustration of two approaches to one application. A Gas Heated Reformer was combinedwith a Gas/Tube Cooled converter with high conversion at a low temperature and a Water Cooled Converter using saturatorwater as the cooling fluid so that the heat recovered goes back into generating process steam. The second approach is a novelarrangement comprising a radial flow Steam Reformer with an axial Steam Raising Converter. Compared to a conventionallarge capacity synthesis loop, this design operates with 30% lower recycle while achieving very high conversion and requiringlow catalyst volumes.

For large scale designs it is appropriate to have two methanol converters in series. A gas heated reformer may be combinedwith a gas/tube converter followed by a water cooled converter using saturator water as the cooling fluid. The major part of thereaction is carried out in a conventional gas/tube cooled converter, but to get the best possible conversion it is necessary toreach equilibrium at a lower temperature. This is done in a steam raising converter using saturator water as the cooling fluid sothat the heat recovered goes back into generating process steam, equivalent to raising steam at 50 bar on a GHR + ATR plant.This arrangement allows methanol content to be as high as 10% with low recycle gas flow rate so that axial flow reactors cancontinue to be used up to 6,000 TPD or higher.

Davy Process Technology has developed a new synthesis loop technology that is also suitable for large scale designs. In thisapproach, a conventional steam reformer is combined with two identical reactors in series. These may be twin radial flow steam-raising converters, axial steam-raising converters or gas/tube cooled converters. Compared to a conventional methanolsynthesis loop, this new design operates with an approximately 30% lower recycle ratio while achieving very high conversionwith low catalyst volumes.

Syngas Syngas SyngasProduct Product Product

Steam

Air

Fuel

Steam

Product

BFW

GasFeed


5/8

Distillation

Davy Process Technology offers a range of designs of methanol distillation systems. Depending on the destined market andappropriate specification, two or three column flowsheets may be chosen. The figure below shows the three column systemused for the recent M5000 plant in Trinidad.

The 5000 MTPD plant flowsheet designed by Davy Process Technology and operated in Trinidad uses a single topping columnbut the larger refining columns are split into two because a single 5000 MTPD column is too big to ship to most sites around theworld. The design of internals including trays and gas and liquid distributors is achieved using detailed hydraulic modelling inorder to ensure that accurate flow distribution is maintained under changing process conditions. When we look to the future, it islikely that methanol will continue to be an internationally traded commodity chemical and also have outlets as a fuel componentand a captive intermediate. Consequently, not all methanol plants will be making AA-grade methanol and for a lowerspecification product, a totally single-stream 5000 MTPD distillation train becomes feasible and further advantages of theeconomics of scale become realisable.

Reforming and Gas Feed Treatment

Davy Process Technology in conjunction with Johnson Matthey Catalystsprovides processes to utilise a wide range of hydrocarbon sources inmethanol synthesis. We have designs for extensive ranges of methanerich gases that may include carbon dioxide, nitrogen and heavierhydrocarbons. We also provide designs for gases generated from coal,shale oil, refinery petrocoke and sub-surface coal gasification. We treat,condition or purify these gases so they are suitable for one of ourextensive range of reforming technologies, including:

- Steam Reforming- Compact Reforming- Auto Thermal Reforming- Combined Reforming- Gas Heated Reforming

We also work closely with different gasification technologies and have,with Johnson Matthey Catalysts, flowsheet designs and catalysts toprocess and condition gases that need shift, impurity removal and CO2removal. We illustrate our expertise in the following associated

brochures: Carbon Conversion TechnologiesGas Conditioning and PurificationSynthesis Gas TechnologyCompact Reformer & GTL Technologies


6/8

Synthesis Gas Compression

The Davy Process Technology flowsheet incorporates aturbine in the second stage of the synthesis gascompressor. Even with a turbine limit (for high-speedduty) of 70MW further improvements have been made toenable the flowsheet to deliver in excess of 6500 MPTDof methanol. These include permutations of thefollowing options:

reduction of the discharge (loop) pressure

housing the circulator in a separate casing

adding carbon oxides

Reducing the loop pressure is more than counter-balanced by improvements in synthesis reactor designand reduced rate of circulation from enhanced catalystperformance with higher specific conversion efficiency.

Reliability and Cost Effectiveness

Davy Process Technologys tried and tested steam reforming route tomethanol will continue to be used for many applications provided the limits

of design and performance continue to be extended. In this way, newplants inherit reliability gained over many design cycles but have singlestream capacity of double the limit that seemed possible only ten yearsago. Designs for such large plants use equipment normally employed inthe utility industries such as power generating stations. As piping andvalves become larger, wall thickness increases and weight rises so thatthey need their own support structures. Each scale-up developmentdemands extension of specifications in terms of materials of construction,fabrication tolerances and novel systems for installation and increasingthe scale of operation imposes tighter limits on reliability and ease ofmaintenance.

Davy Process Technology ensures that all these requirements aremanaged within projects that in scale and value are major infrastructurecontracts. The new designs of very large methanol plants are so reliablethat they increase plant availability and as cost effectiveness is directly

related to plant availability this is the motivation to improve processtechnology.

Further economic improvements will derive from integrating reforming,methanol synthesis and conversion to olefins. These developments mustbe coupled with detailed design of all the component parts so that provenreliability is built in. Davy Process Technology has the reputation forsupplying the most commercially attractive methanol process technologyand is actively working to extend both size range and process flexibility.We are determined to stay in the vanguard of these developments and willcontinue to work with the major plant operators to deliver the most cost

effective process solutions.

Products

The predominant chemical used for methanol is as the raw material for acetic acid and formaldehyde production, an importantcomponent in the manufacture of urea formaldehyde resins for the construction industry. It is also used as a solvent, a fuel andin power generation. It is also seen as a future intermediate in the production of olefins (MTO). Technologies are also availablefor the conversion of methanol to dimethyl ether (DME) which can be used as a fuel either in a gas turbine or a power station.


7/8

Methanol Production Offshore

Davy Process Technology is working with a group of clients who are interested in taking methanol technology offshore toaccess new gas sources. For such cl ients we can offer a variety of solutions:-

All the major technical and safety issues have been addressed and satisfactory solutions have been found for catalystloading/unloading in a ship environment. Equipment optimisation has been completed with innovative integration into acommercial flow sheet capable of producing 2,500 tonnes/day of methanol. If a project has gas and offshore operation is anoption, then the first consideration is the type of structure. There are two basic types that are appropriate: a fixed system such

as a CGS (Concrete Gravity Structure) and an FPSO (Floating Production, Storage and Offloading).

Fixed Platform

A CGS becomes in effect an artificial island. The structure can beconstructed in a yard and then floated to the location where it is to be sited.This can be done with the process equipment in place which enablesconstruction to take place in a low construction cost location. Once at theproduction location the GCS is ballasted to sink it into place. This type ofstructure therefore requires relatively shallow water near to the gas wellhead.

An example of a project that is following this approach is the MethanolAustralia project that is planned to be located on the Tassie Shoal. For thistype of structure the topside weight is not a major issue as it is supportedfrom the sea bed. There is also no limit to the plot space available and therefore no particular limit to the size of plant that can

be built on this type of structure. Additional plot is expensive and so technologies that minimise plot space are still desirable.On the CGS, the process unit will be deck mounted with the utilities below deck and the storage of methanol within the CGS.

As the GCS is fixed to the sea bed, vessel motion is not an issue and therefore any of the synthesis gas technologies presentedabove could be used on this type of structure.

Floating Production

A FPSO is in effect a boat with all that is necessary to produce the oil, gas andmethanol contained on it. The vessel will have a mooring system to hold it inplace, gas processing, methanol production, utilities, product storage andaccommodation for the crew and operators. The process plant and utilities willbe installed on the topside with storage below deck. This vessel is readilymovable and therefore is suited to use on fields with limited lives. In additionMFPSOs can beneficial where there is perceived country risk and the operatorwants to have the ability to move its plant assets to alternative locations. TheMFPSO is a boat and therefore space and weight are substantially more

important than for a CGS. In addition the vessel will be subject to motion andthis needs to be carefully considered when selecting the process technology.

In general it is expected that the MFPSO option will have a higher cost than the CGS and therefore if the water depth and fieldlife is sufficiently long we would expect a fixed platform to be the first choice. Vessel motion, weight and space are the keyconsiderations for MFPSO plants. Most methanol plants involve the use of a steam reformer be it in a conventional orcombined reforming process. Steam reformers are large and heavy items and the refractory systems and unrestrained tubesystems mean that they are not suitable for the movement that can be experienced on a FPSO. The very large fired heaternecessary for autothermal reforming is also not suited to such movement. This leaves two technologies that can be adapted foruse on a FPSO: Compact Reforming and Gas Heated Reforming. These technologies also have the benefit of saving bothspace and weight. As mentioned earlier the compact reformer can accommodate gas with high levels of CO2 without the needfor CO2 removal and is therefore particularly suited to processing of high CO2 gas on a FPSO.

Floating Distillation

An operator who is considering an offshore project will also have to consider

if the project should refine the methanol on the FPSO. If the methanol is to beused only for MTO applications it may not be necessary to perform anydistillation. If the entire production is going to pass through a single terminal,the methanol could be refined at the terminal before being distributed tocustomers. These options would reduce the size and weight of the topsidesrequired, however it would require the additional weight of the water in thecrude to be shipped in the product. This may add to the shipping weightdepending on the production technology used. The operator may wish to beable to transport material directly from the FPSO to their customers and inthis case offshore refining will be needed.


8/8

Documents

Methanol Technology