Operations

Methanol

Overview

The Coogee Methanol plant in Laverton Victoria is a joint venture between Coogee Chemicals and Mogal Marine Pty Ltd and is operated by Coogee Energy Pty Ltd, a wholly owned subsidiary of Coogee Chemicals. It is the only methanol plant in Australia, and supplies approximately 80% of Australia’s methanol requirements.

The plant is based on the Leading Concept Methanol process, which was developed by Johnson Matthey Catalysts in the UK. This plant was originally constructed by BHP Petroleum to research and develop offshore methanol production.

Methanol Process

  • Methanol Process Description

    The Leading Concept Methanol process in use at the Coogee Methanol Plant has various advantages compared to the conventional methanol processes. Some of those advantages are that it is efficient and compact and substantially reduces waste through the internal recycling of process effluents.

    Natural gas feedstock is delivered to the plant via a pipeline from the main Melbourne-to-Geelong trunkline carrying Bass Strait gas. The gas is first compressed and then purified by removing sulphur compounds. The purified natural gas is saturated with heated and recycled process waste water. The mixed natural gas and water vapour then goes to the gas heated reformer to be partially converted to synthesis gas, a mixture of carbon dioxide, carbon monoxide and hydrogen. This partially converted gas is then completely converted to synthesis gas by reaction with oxygen in the secondary reformer.

    The synthesis gas is then converted to crude methanol in the catalytic synthesis converter. The crude methanol is purified to standard quality specifications by removing water and organic impurities through distillation. The water and organic impurities are recycled.

  • Process Description

    The Coogee Energy plant is designed to produce 164 tonnes per day of methanol from about 5 TJ/day of Bass Strait natural gas.

    Typical Bass Strait gas composition:

    COMPONENT Mol%
    Methane 90.7
    Ethane 5.9
    Propane 0.6
    Butane 0.1
    Nitrogen 0.9
    Carbon Dioxide 1.8

    The plant consists of four main process steps: feed gas preparation, synthesis gas generation, methanol synthesis and distillation supported by utilities and offsite units.

  • Feedgas Preparation

    Natural gas is compressed to about 45 bar and sulphur removed by hydrodesulphurisation in the purifier. The desulphurising gas is cooled and flows to the saturator where it is contacted with hot water over a bed of packing. The saturated gas leaving the vessel contains about 92% of the steam required for reforming. Saturator make up is 90% process condensate and the balance refining column bottoms water. Prior to leaving the saturator the gas stream is contacted with recycled fusel oil where waste products from methanol synthesis are stripped off. A blowdown stream is required to control dissolved solids. Additional steam generated in the boiler is made up to the gas stream to achieve 3.0:1 steam to carbon ratio for reforming.

    The total feedstream is then heated in the gas heated reformer pre-heater. Both the pre-heater and boiler are fired with a mixture of synthesis loop purge gas and natural gas.

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Synthesis Gas Generation

  • Reactions

    There are three main chemical reactions which occur in this process step:

    Steam reforming - CH4 + H2O = CO + 3H2
    Shift reaction - CO + H2O = CO2 + H2
    Combustion - 2H2 + O2 = 2H2O

    The net effect of these reactions is the production of a synthesis gas stream which is composed of carbon monoxide (CO), carbon dioxide (CO2) and hydrogen (H2).

    These reactions are carried out over catalysts.

  • Description

    Preheated gas flows from the pre-heater to the tube side of the advanced gas heated reformer (AGHR). The feedstock is heated from the feed temperature of 425° C as it passes down through the catalyst and the reforming reactions start. The AGHR contains 19 reforming tubes which contain the reforming catalyst.

    Hot reformed gas exits the bottom of the reforming tubes and flows to the tube side exit of the AGHR at about 700°C. The heat required for the endothermic reforming reaction is derived from cooling the secondary reformer effluent in the shell side of the AGHR. About one quarter of the methane is reformed in the AGHR.

    The partly reformed gas flows from the AGHR to the combustor/secondary reformer where the bulk of the reforming takes place. The heat required for the endothermic reforming in both the AGHR and secondary reformer is provided by partially burning the AGHR effluent with pure oxygen in the combustor located integrally at the top of the secondary reformer. Oxygen is injected into the gas via a specially designed gun. About 0.50 tonne of oxygen per tonne of methanol is required.

    The oxygen is completely consumed and the resulting hot gas stream passes over the secondary reforming catalyst. Reforming reactions continue and the gas leaves the secondary reformer at up to 1000°C with less than 0.5% methane slip. The secondary effluent passes to the AGHR shell and thence through the heat recovery train to provide heat for the saturator circuit and distillation re-boilers. The process condensate which condenses out of the reformed gas is recycled back to the saturator. After heat recovery the reformed gas is finally cooled and then compressed to about 70 barg in the synthesis gas compressor to be fed as synthesis gas to the synthesis loop.

    Bass Strait natural gas contains about 91 mol% of methane, 6 mol% of ethane with the balance being predominantly propane, nitrogen and carbon dioxide. On an offshore facility with less sophisticated gas separation facilities there may be higher levels of higher hydrocarbons such as components but the oxygen consumption would increase.

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Methanol Synthesis

  • Reactions

    There are two main chemical reactions which occur in this process step:

    CO + 2H2 = CH3OH
    CO2 +3H2 = CH3OH + H2O

    The net effect of these reactions is the production of a crude methanol stream which is about 80% methanol and 20% water.

    These reactions are also carried out over a catalyst.

  • Description

    The synthesis gas joins the synthesis loop recycle gas from the circulator to pass through the loop interchanger and be fed to the methanol converter at about 130° C. The converter is a tubular cooled converter design where the gas is preheated to reaction temperatures inside the tubes as it flows up through the hot catalyst bed. This type of converter maximises catalyst efficiency as it enables a temperature profile to be maintained inside the converter that is close to the maximum reaction rate curve. The hot reacted gas leaves the converter and provides heat to the saturator water circuit and the loop interchanger before finally being cooled. Crude methanol is separated from the uncondensed gases in the loop catch pot and the gases recirculated back to the converter via the circulator.

  • Distillation

    Crude methanol from the loop catch pot is filtered to remove traces of wax, let down in pressure and fed to the product purification section. This section consists of a topping column and a refining column. Unlike most methanol distillation columns these columns are packed with structured packing. Re-boiler duty is provided by reformed gas. The product methanol specification is for a water content of less that 0.10 wt %. The water bottoms from the refining column have a specification of less than 100 ppm of methanol and are recycled back to the saturator. Other synthesis by-products such as higher alcohols are collected as fusel oil and recycled back the saturator.

  • Utilities and Offsites

    An air compressor, demineralisation plant, cooling water system, flare, firewater system, crude and refined methanol tanks provide the supporting utilities and offsite facilities. All rotating equipment is motor driven and the power demand of the plant is about 2.2 MW.

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Safety Features

A comprehensive safety management system has been implemented to provide best practice procedures for maintaining the highest performance of operating safety and occupational health. All employees are trained through a competency based system and implementation is audited regularly.

The plant has modern safety features typically used including instrumentation with alarms, trips and interlocks. These are used to minimise the occurrence of hazardous incidents or warn of their possibility. Plant equipment is protected from overpressure by pressure safety valves which relieve to a clean burning smokeless flare stack.

In the event of a gas leak, the plant has flammable and toxic gas detectors to provide early warning so the plant can be safely shut down. Equipment is routinely monitored and checked to detect minor leaks.

Product methanol is stored in two 2000 tonne tanks which have fixed external roofs and floating internal roofs with nitrogen above them to act as an inert buffer. This design minimises any risks of fire in the tanks and also minimises fugitive vapour emissions.

The plant is equipped with fire water pumps, a deluge system and fire detection equipment.

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Floating Methanol – Proposed Future Development

  • Building a Floating Methanol Plant

    Australia has large undeveloped reserves of natural gas that are remote from major areas of consumption. By converting the gas to methanol, an easily transportable liquid, the economic and environmental benefits of natural gas will be more readily available.

    The purpose of the plant is to test the methanol conversion technology known as Leading Concept Methanol (LCM) for offshore use. Such an application would be on board a floating production facility called a Methanol Floating Production, Storage and Offloading Vessel (MFPSO).

    The key criteria for an MFPSO are:

    • Safety and operability
    • Reliability
    • Compact design
    • Weight compatible with vessel design
    • Insensitivity to motion effects
    • Minimised effluents
    • Minimised utility requirements
    • Low manpower requirements
    • Integration with FSPO hydrocarbon production

    Methanol technology based on conventional steam reforming is inappropriate for an MFPSO because of the size and safety implications of the fired reformer. A number of other aspects associated with conventional plants have to be addressed. These include the amount of water required in the process (all water requirements have to be generated from sea water) and the effect of motion on the very large distillation columns.

    Years of research and development have eliminated any technical hurdle envisaged in preventing the LCM technology from being used for the first MFPSO.

    Coogee Chemicals and Mogal Marine (in conjunction with Mitsubishi Corporation) own the intellectual property for an MFPSO and are actively pursuing opportunities for the commercial application of this technology to offshore stranded gas fields.

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Buying Methanol

The bulk of methanol produced at the Coogee Methanol Plant is sold to local formaldehyde producers via dedicated methanol pipelines.

Coogee Energy also supplies methanol to a range of smaller, more specialised methanol users and retailers from its road tanker loading facility in Laverton and its offsite storage in Botany, NSW and its Brisbane Tank Terminal.

The plant produces methanol that meets the British Standard (BS506) Part 1 methanol specification.

The plant has an NATA accredited laboratory capable of testing aspects of methanol quality in accordance with BS506 specification.

All road tankers picking up methanol from the plant must meet specified equipment/safety requirements.

If you would like more information about purchasing methanol please email your enquiry to ceadmin@coogeeenergy.com.au

Methanol MSDS

Download the Methanol MSDS here.

Environment Improvement Plan

Download the 2003 Environment Improvement Plan here.

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