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AMR Process Methanol Recovery Unit

AMR Process Inc. designs & supplies methanol recovery and methanol regeneration systems. The AMR Process Inc. methanol recovery & methanol regeneration unit removes methanol from the water phase. The AMR Process Inc. methanol recovery & methanol regeneration unit consists of separation and high efficiency distillation. Steam stripping can additionally be utilized where product water quality is a  factor in design. With its high volatility the methanol recovery & methanol regeneration unit generally requires relatively low utility requirements, which are usually already available on site. A basic modular approach to the AMR Process Inc. methanol recovery & methanol regeneration unit can be customized to suit particular constraints of utility availability, height & plot limits.

The increasing cost of methanol, transportation, storage, environmental concerns & hazards associated with the handling of methanol, makes the AMR Process Inc. MeOH recovery & MeOH regeneration unit an attractive proposition. Methanol cost generally follows the sales price of gas. With the gas price being stable at a high price, methanol cost has become a primary factor in production costs and the use of the AMR Process Inc. MeOH recovery & MeOH regeneration units provides a significant contribution in cost recovery.

Hydrates

Methanol is commonly used as a hydrate inhibitor. A hydrate is a physical combination of water & other small molecules to produce a solid which has an "ice like" appearance. Hydrates can form in wet natural gas which can plug pipes, valves, flow lines, process equipment & safety systems. Hydrates will form when the wet natural gas undergoes a temperature drop below its "hydrate point". This commonly occurs during pressure reduction such as control valves, orifices and well heads.

The solution is to remove the water by dehydration or inject an hydrate inhibitor, such as ethylene glycol (EG), triethylene glycol (TEG) or methanol injection. Glycol injection requires high injection rates and provides a minimal depression in hydrate point. It is also viscous at low temperatures. Methanol injection hydrate inhibitor can achieve high dew point suppression and is the most effective hydrate inhibitor.

Estimates on the minimum hydrate inhibitor concentration in the free water phase can be obtained using the following equation:

            d = K_H (I) / (100 MW_I - (MW_I) (I) )                     

d = depression of the water dew point or the gas hydrate freezing point, °F

I = weight % hydrate inhibitor in the liquid phase

K_H = 4,000 for glycol, K_H = 2,335 for methanol 

MW_I = 62 for ethylene glycol (EG), MW_I = 150 for triethylene glycol (TEG), MW_I = 32 for methanol

The amount of hydrate inhibitor to be injected not only must be sufficient to prevent freezing of the inhibitor water phase, but also must be sufficient to provide for the vapor phase and the solubility in any liquid hydrocarbon. The vapor pressure of methanol is high enough that significant quantities will vaporize. Total injection rates of methanol may be about three times that needed to maintain water concentration. No allowance need be made for glycol vaporization.

The hydrate inhibitor that remains in the water phase is normally collected in the inlet separator and carried through to the skim tank/water treatment. AMR Process Inc. methanol recovery & methanol regeneration unit removes the hydrate inhibitor from this water phase providing a high purity methanol product and minimal left in the water.

Methanol Properties

For its MSDS sheets please click on tab:

Typical Methanol Recovery Performance

The AMR Process Inc. methanol recovery unit performance guarantee provides the following methanol purities:

• Feed                    5-50% wt
• Product              > 92% wt
• Waste water      < 2,000 ppm (wt)

Designs can be customized to provide alternative performance guarantees where required.

Additional process equipment, as modular "additions", can also provide the following design factors:

• Pure water product
• Sour service

Methanol Recovery Unit Operating Profit

A simple calculation can provide the operator with an estimate on the operating profit of AMR Process Inc. recovery unit.

• Measure the quantity of water taken from inlet separator / water treatment unit that contains the methanol.

• Analyze the quantity of methanol in the water (notes this varies according to ambient temperatures). We have found this quantity to average in the 10-12% volume range.

• Electrical costs required for pumps/air coolers we have found to be approximately 0.5 kWh per m3/d of water processed.

• Heating costs required for reboiler heating we have found to be approximately 30 kWh per m3/d of water processed.

• Methanol recovery savings can be calculated using CAN$450 per metric tonne (CAN$0.57 / liter)

Example:

• Process 70 m3/d water with 11% average methanol content

• Electrical costs = 0.5 x 70 = 35 kWh @ $0.07/kWh = $59 /day ⁽²⁾

• Heating costs = 70 x 30 = 2,100 kWh @ $0.016/kWh = $806 /day ^(1,2)

• Methanol recovery savings = 7.7 m3/d @ $570/m3 = $4,389 /day ⁽²⁾

• Operating profit = $3,524 /day = $1,228,260 /year

(1)    Some of the utility costs could be reduced according to heat utilities on site. For example utilizing molecular sieve regeneration gas or excess steam as a partial heat source for the methanol recovery unit.

(2)    Current utility and methanol prices should be checked & substituted where necessary.

Studies by AMR Process for large operating companies in Canada, have shown that the AMR Process methanol recovery unit provides extensive operating profits, which pays back the capital costs of the methanol recovery unit in a relatively short period of time, and provides additional extensive operational savings to the user.

AMR Process Inc. would be pleased to  perform a preliminary analysis for the user of operating & capital costs, provide project recovery time lines and economic savings estimates, utilizing the AMR Process Inc. methanol recovery and methanol regeneration unit.