NO780801L - PREPARATION OF PUREED SYNTHESIS GAS AND CARBON MONOXIDE - Google Patents

Abstract

Preparation of purified synthesis gas and carbon monoxide.

Description

The present invention relates to a partial oxidation process in which synthesis gas is simultaneously produced with a regulated molar ratio Hp/CO and either a CO-rich gas or essentially pure CO. Methanol can be produced from the synthesis gas and can then be reacted with the CO-rich gas or with essentially

just pure CO for the production of acetic acid.

Synthesis gas can be produced by partial oxidation of fossil fuels with a gas containing free oxygen, possibly in the presence of a temperature moderator. The waste gas stream from the gas generator is cooled (to below the temperature at which the gas composition approaches equilibrium), e.g. by direct introduction into water in a quench drum as described in US patent no. 2,896,927. In this method for gas cooling, the sensible heat in the waste gas flow is used. to produce steam in the product gas.

Alternatively, the waste gas stream from the gas generator can be cooled in a synthesis gas cooler as shown in US patent no. 3,920,717 - In this method for gas cooling, the waste gas stream is not saturated with water. In US patent no. 3,929-^29, in order to produce an oil-carbon dispersion and a separate water-carbon dispersion, which are simultaneously fed to a gas generator for the production of fuel gas, a portion of the waste gas stream is cooled in a synthesis gas cooler and then washed with oil; and another stream is quenched in water. Non-catalytic thermal shift using

is tested to adjust the /CO molar ratio in a single stream of the synthesis gas in US Patent No. 3,920,717-

In the present method, the waste gas stream directly from a free-flowing non-packed non-catalytic partial oxidation synthesis gas generator may have a ω/CO molar ratio in the range 0.5-1.9 and may contain entrained particulate solids, i.e. axis and core bonsot. A proportion of the ash, if present, can first be removed as slag. The gas stream is then cooled by indirect heat exchange in a gas cooler and the boiler feed water is thereby converted into steam. Remaining entrained solids, i.e. particulate carbon, are then removed. The soot-free gas stream is dehumidified, and then part of the soot-free and dehumidified gas stream is supplied to a first gas cleaning zone. The rest of the soot-free and dehumidified gas flow, if there is any left, is led past

.the first gas cleaning zone. In the first gas cleaning zone, depending on the composition of the gas stream, F2S, COS and at least some CO2 are removed in a conventional manner. This can happen

in one or two steps. Gas, which has been treated in the first gas purification step, is supplied to a second gas purification step or a separation zone where, using normal procedures, a product stream of CO-rich gas and a separate stream of h^-rich gas and possibly CH^-rich gas are separated. For example, at least a part of the gas is passed from the first gas cleaning zone and which does not contain E^ S and COS

and where at least part of the CO2 is removed, to the second gas cleaning zone. The rest of the gas treated in the first gas cleaning zone,

if anything is left, it is led past the second gas cleaning zone. The product stream of purified synthesis gas with a regulated ^/CO molar ratio, i.e. in the range 2-12, is produced by mixing together at least part of the l^-rich gas from the second gas purification zone with at least one, i.e. either one or both of the following:

(a) gas treated in the first gas cleaning zone which was passed past the second gas cleaning zone; and (b) soot-free dehumidified gas stream which is passed past the first gas cleaning zone.

For example: In an embodiment where the soot-free and dehumidified synthesis gas stream is substantially free of P^S and COS, h^-rich gas may be mixed with at least a proportion of at least one of the following: (o) soot-free and dehumidified gas which is passed past the first gas cleaning zone; (b) soot-free and dehumidified gas with at least a proportion of the C02 removed from the first gas cleaning zone and which is passed past the second gas cleaning zone.

In another embodiment where the soot-free and dehumidified gas contains H^S and COS, H^-rich gas may be mixed with at least a proportion of at least one of the following:

(a) desulfurized gas from the first stage of the first gas cleaning zone; (b) desulphurised gas in which at least a proportion of CC^ is removed from the second stage in the first gas cleaning zone and which is passed past the • second zone.

The catalytic water-gas shift reaction step is not a necessary step according to the invention. Optionally, thermal non-catalytic shift can be used to increase the molar ratio E^/CO in the raw waste gas stream from the gas generator.

In another embodiment, methanol synthesis gas is produced with a molar ratio E^/CO within the range of 2-4 by the above-mentioned method and is then catalytically converted into a stream of raw methanol. Pure methanol is obtained by purifying this stream. A proportion of the pure methanol can be used as a solvent absorbent to remove acid gases from the raw synthesis gas in the first gas cleaning zone. Optionally, at least a portion of the pure methanol can be catalytically reacted with at least a portion of the product stream of substantially pure carbon monoxide to obtain a stream of crude acetic acid which can then be purified to produce glacial acetic acid and, as a by-product, oxygen-containing substances. By-product oxygen-containing substances can be returned to the reaction zone in the gas generator.

The invention will be further explained with reference to the accompanying drawings. Fig. IA schematically shows a preferred embodiment of the method for the simultaneous production of a product stream of pure and purified synthesis gas with a molar ratio E^/CO in the range 2-12 and a separate product stream of CO-rich gas and preferably essentially pure CO. Fig. 1B, as shown to the right of the line A-A, schematically shows another embodiment of the method in which pure methanol is produced from a product stream of methanol synthesis gas produced by the above-mentioned method. Optionally, at least part of said pure methanol can be reacted with at least part of the essentially pure carbon monoxide stream to obtain acetic acid.

In the first stage of the process, • raw synthesis gas, essentially comprising hydrogen and carbon monoxide and with a molar ratio of Hp°S CO in the range 0.5-1.9, is produced by partial oxidation of a hydrocarbon-containing fuel with essentially pure oxygen, optionally in the presence of a temperature moderator in the reaction zone in a non-packed free-flowing non-catalytic partial oxidation gas generator. The weight ratio between steam and fuel in the reaction zone is in the range 0.1-5

and at most 0.2-0.7- The atomic ratio between free oxygen and carbon in the fuel (the O/C ratio) is in the range 0.6-1.6 and preferably 0.8-1.4. The reaction zone is in the range of 1-10 seconds and preferably 2-6 seconds.

The raw synthesis gas exits the reaction zone at a temperature within the range 704-1650°C, e.g. 1093-1538°C, and at a pressure within the range 1-250 atmospheres, e.g. 40-150 atmospheres.

The composition of the raw synthesis gas exiting the gas generator is approximately as follows in mol%: H260-29; CO 30-60; C022-25; H 2 O 2-20; CH^0-25; H 2 S 0-2; COS 0-0.1; N? 0-1 and Ar 0-0.5-There may also be present particulate carbon within the range 0-20% by weight (basic carbon content in original raw material) and ash in an amount of 0-60% by weight of the original hydrocarbon fuel .

The synthesis gas generator comprises a vertical cylindrical steel pressure vessel lined with refractory material, as shown in US Patent No. 2,809-104. A typical quench drum is also shown in the said patent. A burner as shown in US patent no. 2,928,460 can be used for supplying feed streams to the reaction zone.

A wide range of combustible carbonaceous organic substances can be reacted in the gas generator with a gas containing free oxygen, possibly in the presence of a temperature-moderating gas, to produce synthesis gas.

The term hydrocarbon-containing fuel, as used herein to describe various suitable raw materials, is intended to include gaseous, liquid and solid hydrocarbons, carbonaceous substances and mixtures thereof. Thus, essentially any combustible carbonaceous organic material or slurries thereof may be included within the definition of the term "hydrocarbonaceous". For example, there are (1) pumpable slurries of solid carbonaceous fuels, such as coal, particulate carbon, petroleum coke, concentrated sewage sludge, and mixtures thereof, in a vaporizable liquid carrier, such as water, liquid hydrocarbon fuels, and mixtures thereof; (2) gas-solid suspensions, such as finely divided solid carbonaceous fuels, dispersed in either a temperature-moderating gas or a gaseous hydrocarbon; and

(3) gas-liquid-solid dispersions, such as atomized liquid hydrocarbon fuel or water and particulate carbon, dispersed in a temperature moderating gas. The hydrocarbon-containing fuel can have a sulfur content in the range 0-10% by weight and an ash content in the range 0-60% by weight. By definition, expression means

a "substantially sulfur-free hydrocarbon fuel", as used herein, means a hydrocarbon fuel as described above which, when subjected to & n non-catalytic partial oxidation process, yields a crude synthesis gas in the above manner, containing less than 5 ppm H^S and COS.

The term liquid hydrocarbon, as used herein

to describe suitable liquid feedstocks, is intended to include various substances, such as liquefied petroleum, liquefied natural gas, petroleum distillates and residues, gasoline, naphtha, kerosene, crude petroleum, asphalt, gas oil, residue oil, tar sands oil and shale oil, coal-derived oil, aromatic hydrocarbons

(such as benzene, toluene and xylene fractions), coal tar, cycle gas oil from fluid catalytic cracking processes, furfural extract of coker gas oil and mixtures thereof.

Gaseous hydrocarbon fuel, as used herein to describe suitable gaseous feedstocks, includes methane, ethane, propane, butane and other unsaturated light hydrocarbon gases, pentane, natural gas, water gas, coke oven gas, refinery gas, acetylene tail gas, ethylene off gas, synthesis gas and mixtures thereof . Solid, gaseous and liquid raw materials can be mixed

des and are used simultaneously, and these may include paraffinic, olefinic, acetylenic, naphthenic and aromatic compounds in any ratio.

Also included within the definition of the term carbonaceous fuel are oxygenated hydrocarbon-containing organic substances: including carbohydrates, cellulosic materials, aldehydes, organic acids, alcohols, ketones, oxygenated fuel oil, waste fluids and by-products of chemical processes containing oxygenated hydrocarbon-containing organic substances and mixtures thereof.

The hydrocarbon-containing raw material can be present at room temperature or it can be preheated to a temperature of up to 315-650°C, but preferably below the cracking temperature. The hydrocarbon-containing raw material can be supplied to the gas generator burner in liquid phase or in vaporized mixture with the temperature moderator.

The need for a temperature moderator to regulate the temperature in the reaction zone generally depends on the carbon/hydrogen ratio in the raw material and the oxygen content in the oxidant stream. A temperature moderator may not be necessary with certain gaseous hydrocarbon fuels, however one is generally used with liquid carbon fuels and with essentially pure oxygen. Steam can be added as a preferred temperature moderator in admixture with either one or both reactant streams. Alternatively, the temperature moderator can be supplied to the reaction zone in the gas generator by means of separate pipelines in the burner. Other suitable temperature moderators may include CC^ and a proportion of cooled and recycled synthesis gas separated downstream in the process.

The expression free oxygen-containing gas as used herein essentially means pure oxygen, i.e. over 95 mol-% oxygen (with the rest usually consisting of N2 and noble gases). Free oxygen-containing gas can be supplied by means of the partial oxidation burner at a temperature within the range of ambient temperature to 980°C.

A continuous stream of hot waste gas at substantially the same temperature and pressure as in the reaction zone emerges from the axial discharge opening in the gas generator and is cooled in a gas cooler. However, for hydrocarbon-containing fuels that have a high ash content such as coal, a solids separation zone is preferably introduced between the discharge opening in the gas generator and the gas cooler to remove the larger entrained solid particles". This solids separation zone may comprise a slag chamber, a cyclone separator, an electrostatic precipitator or combinations of such elements for removing at least a portion of the solids present, eg particulate carbon, ash, metallic constituents, shale, slag, refractories and mixtures thereof which may be entrained in the hot waste gas stream or which may flow from the gas generator, i.e. slag,

ash and pieces of refractory material. Thus, if present, a proportion of the larger solid particles can be separated from the waste gas stream and recovered with very little, if any, temperature or pressure drop in the process gas stream. A typical slag chamber that can be used is shown in the drawing or in fig. 1 in the drawings in US Patent No. 3,528,930. All coarse solid particles with a size above approx. 12 ym, is preferably removed at this point by gravity or cyclone separation, or another

physical cleaning process. If particulate carbon black is entrained in the waste gas stream, a small amount can be removed together with the coarser particles. However, most of the soot and finer entrained solids are removed later by washing the process gas stream with water. In the preferred embodiment, the water-gas shift reaction step is not required to increase the H 2 /CO mole ratio. This eliminates costly water-gas shift catalysis. Possibly can

in a separate embodiment non-catalytic thermal shift, as described in US Patent No. 3-723,345, is used.

In such a case, the flow of hot waste gas from the gas generator is led to a separate refractory-lined free-flowing reaction chamber where some of the entrained solids are removed and adjustment of the mole ratio H2/CO is effected. Preferably, the process gas stream has a temperature in the range 870-1927°C as it is produced in the gas generator and is at the same pressure as in the gas generator, e.g. 15-200 atmospheres, preferably 60-150 atmospheres. A chamber, such as shown in US Patent No. 3-565-588, can be used. For example, the spherical chambers 37 as shown in the drawing are unpackaged and free of catalyst or other obstructions to gas flow through the chamber. A proportion of the solids that can be entrained in the process can fall out and be removed through an outlet arranged at the bottom of the spherical chamber and which leads to a suitable bin.

A stream of supplementary H20, i.e. steam produced later in the process, is simultaneously fed to the spherical chamber at a temperature in the range 260-850°C and a pressure just above that in the gas generator. On a dry basis, approx. 0.1-2.5 mol supplementary H20 to the spherical chamber per moles of waste synthesis gas from the gas generator whereby the gases are mixed. Alternatively, supplemental HpO can be supplied to the separate non-catalytic unimpeded thermal shift conversion zone in admixture with waste synthesis gas from the gas generator. In non-catalytic thermal direct water-gas shift reaction at a temperature of at least 815°C and preferably 926-1538°C, supplementary H20 reacts with a proportion of the carbon monoxide in the waste synthesis gas stream from the generator, so that additional H2 and C02 are formed. The H 2 and C 0 2 i waste gas flow of gases from the gas generator can be increased at this stage to a value of about 0.8-6, e.g. 2.0-4.0. The aforementioned high-temperature, adiabatic, non-catalytic, thermal, direct water-gas shift reaction can begin e.g. in the insulated spherical chamber.' The shift reaction can continue in an insulated line which connects the side outlet of the spherical chamber with the intake arranged at the bottom of a gas cooler. Thus, the waste gas stream of synthesis gas can be thermally shifted without a catalyst in the transfer between steps in the process. The residence time in the water-gas shift transformation zone is in the range of 0.1-5 sec. Preferably, the conditions of pressure and temperature at which the non-catalytic thermal direct water-gas shift reaction occurs are substantially the same as those present in the synthesis gas generator, minus normal pipeline losses and minus cooling due to sensible heat in supplementary H^O and any heating due to the heat of reaction.

The process gas flow is then passed through a separate gas cooler arranged in the production line in indirect heat exchange with water. The flow of synthesis gas is cooled to a temperature within the range 554-400°C. Saturated steam as a by-product can thereby be produced at a pressure above the pressure for the synthesis gas for use elsewhere in the process. Essentially the entire steam requirement in the system can thus be met. For example, the previously mentioned steam can be used as working fluid in an expansion turbine for power generation. The steam turbine can be used to drive air and oxygen compressors in a normal air separation unit, the recycle gas compressor in the methanol synthesis loop which will be described in more detail later, or the feed gas compressor if this is available.

Preferably, part of the steam is supplied to the gas generator as at least a part of the temperature moderator and to the thermal shift reactor as reactant. It can also be used to provide heat in a boiler in a methanol or DME distillation column.

The flow of synthesis gas from the waste heat boiler can be passed through a gas cleaning zone where any remaining entrained solid particles are removed.

If there are essentially no entrained particulate substances in the process gas flow, as is the case with certain gaseous raw materials, both gas cleaning zones can be bypassed or eliminated. The amount of solid particles, i.e. from the group of particulate carbon, ash and mixtures thereof, which can be entrained in the synthesis gas, depends on the type of hydrocarbon-containing fuel and the atomic ratio between 0 and C in the reaction zone. When the generator fuel contains metals, i.e. nickel and vanadium compounds, a small amount of entrained particulate carbon, approx. 1-2 weight-5? (basis weight of C in hydrocarbon-containing feedstock)-increase the lifetime of the refractory lining in the gas generator.

Any suitable device can be used to clean entrained solid particles from the process gas stream. For example, the gas stream leaving the "gas cooler" may be contacted with a scrubbing liquid such as water or liquid hydrocarbon in one or more stages in a gas scrubbing zone, as described

in US Patent No. 3,544,291. The solids that are dispersed in the washing liquid from the gas cleaning zone can be returned to the gas generator as at least part of the fuel. Thus, if the gas stream is washed with water, the dispersion of particulate carbon and water that is formed can be concentrated or separated in the usual way to obtain clarified water. This water can be returned to an orifice, nozzle or venturi washer in the gas cleaning zone. The carbon concentration can be carried out in any suitable way, e.g. by filtration, centrifugation, gravity settling or by commonly known liquid hydrocarbon extraction, as described in US patent no. 2,992,906.

The gas stream from the cleaning zone is cooled to below the dew point

by indirect, i.e. non-contact heat exchange, and then supplied to a "knockout" or separation vessel in which essentially all water is removed to obtain a clean, i.e. soot-free and dehumidified gas stream.

When the HgS and COS content in the soot-free dehumidifying gas stream is less than approx. 5 ppm, the gas stream does not need to be desulphurised. In such a case, the first gas cleaning zone is only used to remove at least a part, i.e. approx. 10-100 volume-% of the C02 present. 10-90% by volume of the clean dehumidified gas from the partial oxidation gas generator is supplied to the first gas cleaning zone. The rest of the soot-free dehumidified gas stream, if at all, is passed past the first cleaning zone. The CO 2 -rich gas stream removed in the first gas cleaning zone may comprise, by weight, the following: C0240-100;

<H>25-25; CO 10-40 and CH^0-5-

When a share, e.g. 10-90 volume-?, of the soot-free dehumidified synthesis gas is led past the first gas cleaning zone, at least a proportion, i.e. 10-100 volume-% of the gas flow from the first gas cleaning zone with at least a proportion of the C02 removed, is led to a second gas cleaning zone. The rest of the gas flow from the first gas cleaning zone, if at all, is led past the second gas cleaning zone. When no soot-free dehumidified synthesis gas is passed past the first gas cleaning zone, a proportion, 10-90% by volume, of the gas flow from the first gas cleaning zone is led to the second gas cleaning zone and the rest, about 90-10 volume- is led past the second gas cleaning zone zone. In this embodiment, there is thus always at least one gas stream which is led past the first, second or both gas cleaning zones and which can be mixed with the H^-rich gas stream produced in

the second gas cleaning zone to give the product, synthesis gas.

A CO-rich product gas stream and an E^-rich gas stream are separated

in said second gas cleaning or separation zone. The composition of the CO-rich gas stream produced in the second gas cleaning zone is approx. as follows in mol%: CO 61-99; N 2 0-1; C020-15; E^ 2-8; CH^0-1 and Ar 0-0.5- Preferably, by further purification, essentially pure carbon monoxide (90-99.5 mol-%) CO can be produced. The H^-rich gas stream which is produced in the second purification zone can comprise, in mol%: H298-60; CO 0-5; C020-5; CH^

0-5; Ar 0-4 and N20-20.

From approx. 20-100% by volume and preferably all H2-rich gas stream can be included as one of the constituents of the product gas. The rest of the H2~rich gas stream can be used for other purposes.

When the soot-free and dehumidified process gas stream so to speak does not contain H2S and COS, the product gas stream of purified synthesis gas is made by mixing at least one part, 10-100% by volume, of said H2-rich gas stream, with at least one part, about 10- 100% by volume of at least one of the following gas streams: (a) soot-free dehumidified gas passed past the first gas cleaning zone; (b) soot-free dehumidified gas with at least one proportion of C02 removed and which leaves the first gas cleaning zone and is led past the second gas cleaning zone. Mixtures of (a) and (b) may comprise 10-90 volume-? of (a) and the remainder (b).

In another embodiment and where more than 5 ppm of acid gases, i.e. H2S, COS and C02, are present in the soot-free dehumidified gas stream,

all this gas is supplied to a first gas cleaning zone which comprises a first stage for desulphurisation of the process gas streams and a second stage for removing at least one proportion of C02. At least one share.

i.e. 10-100% by volume of a desulphurised gas stream from the first stage is supplied to the second stage where at least one proportion of CC^ is removed. The remainder of the desulphurised gas stream is led past the aforementioned second stage and the second gas cleaning zone. One or more liquid solvent absorbents can be used in the two stages to absorb acid gas units. The loaded liquid solvent absorbents are then removed from the absorption tower and regenerated by heating, stripping, or flash evaporation or a combination thereof to obtain a purified liquid solvent absorbent which is then returned to the conventional gas absorption tower. The acid gases are recovered during the regeneration of the solvent absorbent and can be fed to a Claus unit for the production of sulphur. Where a proportion of the desulphurised gas from the first stage is led past the second, i.e. the CC^ absorption stage in the first gas cleaning zone and the second gas cleaning zone, at least one proportion, 10-100 volume, of the desulphurised gas stream leaving the second stage in the first 'gas cleaning zone, supplied to a second gas cleaning zone where I^-rich gas stream and a CO-rich product gas stream are separated. The rest of the gas flow that leaves the second stage in the first gas cleaning zone is, if applicable, led past said second gas cleaning zone. When, alternatively, all desulphurised gas flow from the first stage is supplied to the second stage in the first gas cleaning zone, then a proportion, 10-90% by volume of the desulphurised gas with at least one proportion CC^ removed from the first gas cleaning zone, is supplied to the second' gas cleaning zone. The rest, 90-10% by volume of the gas stream leaving the second stage in the first gas cleaning zone, is led past the second gas cleaning zone. In this embodiment, there is thus always at least one gas stream that is led past the second gas cleaning zone which can be mixed with E^~rich gas to obtain purified synthesis gas product. As mentioned earlier, the H^-rich gas is produced in the second gas cleaning zone together with a CO-rich product stream.

The product stream of purified synthesis gas and with a regulated molar ratio E^/CO is produced in this embodiment in the following way. At least one proportion, 10-100% by volume, of the H^-rich gas from the second gas cleaning zone is mixed with at least one proportion, 10-100% by volume, of at least one, i.e. either one or both of the following gas streams: ( a) desulfurized gas stream from the first stage which is passed past the C02_ removal stage in the first gas cleaning zone; (b) desulphurised gas stream with at least one proportion, 10-100 volume-% of the C02 removed, and which leaves the second stage in said first gas cleaning zone and is led past said second gas cleaning zone. Mixtures of (a) and (b) may comprise 10-90% by volume of (a) and the remainder (b).

Alternatively, a liquid solvent absorbent can be used which absorbs all H₂S and COS and at least one proportion of CO₂ in a single-stage absorption tower which constitutes the first gas cleaning zone. In such cases, all clean soot-free dehumidified gas flow is fed to the first gas cleaning zone and a proportion of 10-90% by volume of the desulphurised gas with at least one proportion, 10-100% by volume of C02 removed from the first gas cleaning zone, supplied to the second gas cleaning zone while the rest of this gas stream is led past the second gas cleaning zone. A CO-rich product gas stream and an H^-rich gas stream are separated in the second gas cleaning zone. The clean synthesis gas product stream is produced by mixing together at least one proportion, 10-100% by volume, of said H~2-rich gas stream and at least one proportion, 10-100% by volume of the desulphurised gas with at least one proportion, 10-100 volume % of the C02 removed, and which is passed past the second gas cleaning zone.

Any suitable conventional process may be used to clean the gas stream in the first gas cleaning zone. Typical gas cleaning processes may include freezing and physical or chemical absorption with a solvent1, such as methanol, N-methyl-pyrrolidione, triethanolamine, propylene carbonate or alternatively with hot potassium carbonate.

Advantageously, when methanol is used as solvent, a proportion of the product methanol is used as refreshment in the gas cleaning zone. When washing the synthesis gas with methanol at 0°C and 10 atmospheres, 100 volumes of C02 are absorbed per volume of methanol. This concentration is increased to 270 vol/vol at -30°C. At a high partial pressure for C02, e.g. 17.5 kg/cm 2 , methanol has a very high absorption power. Likewise, cold methanol is an excellent selective solvent for separating H"2S and COS from

C02>For example, the gas stream can be washed with .cold methanol and

the total content of sulphur, H2S + COS, can be reduced to less than 0.1 ppm. By selective absorption of H2S and COS, a very high sulfur concentration is achieved in the exhaust gas, which contributes to economical sulfur recovery.

In physical absorption processes, most of the C02

which is absorbed in the solvent, is released by simple heating.

The rest can be removed by stripping. This can be done best with nitrogen. Nitrogen may be available as an inexpensive by-product when a conventional air separation unit is used to produce substantially pure oxygen (95 mol% Op or greater) for use as free oxygen gas in the synthesis gas generator. Optionally, a proportion of C02 that is separated in the first gas cleaning zone can be returned to the gas generator. The calculated solvent is then returned to the absorption column for reuse. If necessary, a final purification can be done by passing the gas stream through iron oxide, zinc oxide or activated carbon to remove residual traces of H2S or organic sulphur. In the same way, H2S- and COS-containing solvent can be regenerated by sudden heating or stripping with nitrogen or alternatively by heating and refluxing under reduced pressure without the use of inert gas. H2S and COS can then be converted to sulfur by a suitable process. For example, the Clåus process can be used for the production of elemental sulfur from H2S, as described in Kirk-Othmer, Encyclopedia of Chemical Technology, second edition, vol. 19, John Wiley, 1969, page 352. Excess SO2 can be removed and disposed of by chemical bonding with lime or by suitable commercial extraction processes.

In an alternative gas cleaning process that uses self-cooling, from 30-95% of carbon dioxide can be removed from the synthesis gas stream together with essentially all H2S in the first gas cleaning zone. Here, reference should be made to US patent no. 3,614,872, in which a gas of the changed synthesis gas is separated into an enriched hydrogen stream and an enriched carbon dioxide stream by countercurrent cooling with an outgoing stream of liquid CO^ which is expanded and evaporated to

provide low temperature.

The partially purified synthesis gas stream leaves the first gas purification zone at a temperature within the range of -62-121°C and at a pressure within the range of 10-450 atmospheres (preferably substantially equal to the pressure in the reaction zone of the synthesis gas generator minus normal conduction loss). The composition of this partially purified gas stream of synthesis gas is in mol% approximately as follows: H270-30; CO 30-60; C020-15; H 2 O 0-2; CH^O-2; Scar 0-2; N20-15; H2S 0 and COS 0.

The aforementioned streams of partially purified synthesis gas can be divided into two streams depending on the amount and composition of carbon monoxide-rich gas that is desired, and the desired composition of the product stream of synthesis gas. The division can be determined in advance by substance equilibria. Thus, from 10-100% by volume, e.g. 10-90% by volume of the flow of clean and partially purified "synthesis gas" leaving the first gas purification zone is led to a second gas purification zone.

The second gas cleaning or separation zone may comprise any suitable process for separating a CO-rich gas, an H^-rich gas stream and optionally a CH^-rich gas stream. Creep cooling or physical absorption with a liquid solvent, e.g. copper ammonium acetate or copper aluminum chloride, liquid nitrogen and liquid methane can be used.

A system for recovering CO from the gas stream by physical absorption in cold copper liquid in a CO absorption column will be described in more detail. By applying heat and releasing the pressure on the copper liquid in a copper liquid regeneration column, relatively pure copper monoxide is obtained. The reaction is shown in equation I:

In the second gas cleaning zone, at least one part of the waste gas flow from the first cleaning zone can thus be brought into contact with a conventionally packed column or a bowl-type column with a countercurrent flow of e.g. copper(I) acetate dissolved in a water-ammonia solution. The temperature is preferably kept within the range 0-37°C, and the pressure is preferably within the range 50-600 atmospheres. Preferably, the pressure in the CO separation zone is essentially the same as in the gas generator minus the usual pressure loss in pipelines and equipment. By keeping the pressure in the gas generator high enough, it is possible to avoid connecting a gas compressor between the acid gas absorption column in the first gas purification zone and the CO absorption column in the second gas purification zone. Advantageously, the product stream of purified synthesis gas can be released at a pressure that is around that present in the partial oxidation gas generator minus normal losses in intermediate pipelines and equipment.

A typical analysis on a weight % basis of the copper liquid solution may include the following: CU + 10; Cu + + 2.2; CO^(carbonate) 13j9; HCO^(bicarbonate) 1.3 and NH^ 16.5. The acid radical in the aqueous solution can be either carbonate, formate or acetate.

Regeneration of the copper liquid and release of CC^-rich gas stream takes place in a copper liquid regenerator. The pressure difference between washer and regenerator is approx. 68-204 atmospheres, e.g. 109 atmospheres. By reducing the pressure and supplying heat and a free oxygen-containing gas, e.g. air, pure oxygen or mixtures thereof, the direction of equation I can be reversed and carbonate and bicarbonate ions regenerated. The usual temperature range in the regenerator is approx. 76-82°C. Newly added ammonia and e.g. acetic acid can be added to the copper liquor in the regenerator to maintain the correct solution chemistry. Optionally, acetic acid can be produced afterwards in an embodiment of the present process. In a separation process, the partially cleaned synthesis gas stream from the first gas cleaning zone is brought into contact with liquid methane or a sulfur-free liquefied CH^-rich gas comprising at least 85% by volume CH^, such as liquid natural gas,

in a separation column. The bottom streams from the column can then be fed to the partial oxidation gas generator as part of the feedstock.

In one embodiment of the invention, a pure methanol synthesis gas is produced with a molar ratio U^/CO in the range 2-4

by the previously described process steps. In normal catalytic steps, the synthesis gas can be converted to methanol.

The exothermic equilibrium reaction of carbon oxides and hydrogen to produce methanol, as shown in equations II and III below, is favored at low temperatures and high pressure. However, high temperatures may be necessary with certain catalysts to achieve commercially usable reaction rates.

Conventional high-pressure methanol processes work at temperatures in the range 342-400°C at pressures in the range 250-350 atmospheres and with zinc oxide/chromium oxide catalysts.

Conventional low and medium pressure methanol processes

works at temperatures in the range 204-350°C, e.g. 225-270°C,

and at a pressure in the range 40-250 atm. such as e.g. 40-150 atm., and with catalysts consisting mainly of copper oxide with a smaller amount of zinc oxide and a chromium or aluminum oxide. The proportions of these three oxides are 30-60%, 20-40? respectively 5-20%. The duration and thermal stability of the catalyst can be improved by adding manganese or vanadium. Methanol catalysts can be prepared by alkaline precipitation from saline/petrous acid solution followed by drying, calcination and pelletisation. Space speeds can range from 10,000-40,000/hour. The contact time is less than 1 sec. This degree of methanol formation is from approx. 0.3_2 kg/l catalyst/hour.

Optionally, gaseous raw material for the methanol converter may contain 2-12 mol-% C02. Furthermore, the molar ratio H2/(2CO+3C02)

in the feed gas flow to the methanol converter lie in the range 1.01-1.05 - The presence of some C02 reduces the costs for the previous gas purification steps. Furthermore, the greater molar specific heat for C02i compared to CO and the lower heat of reaction for C02en provide more uniform temperature control in the methanol reactor. The presence of CO 2 appears to be beneficial in order to suppress the formation of dimethyl ether. Optionally, C02 obtained from said first gas cleaning zone can be mixed with the methanol synthesis gas to adjust the mole percentage of C02 present.

Each mole of fresh methanol synthesis gas can be mixed with 0-10

mol ick-converted return gas from the methanol converter, i.e.

3-8 mol returned gas per moles of fresh methanol synthesis gas. A steam turbine driven circulating compressor can be used to compress and recycle a mixture comprising the fresh methanol synthesis gas and the recycled gas. The working fluid for the turbine, e.g. steam, can be obtained from the main synthesis gas cooler after the gas generator.

The feed gas mixture to the methanol converter is preferably preheated by indirect heat exchange with the gaseous effluent from the methanol converter at a temperature in the range 260-427°C

and at a pressure within the range 20-450 atm., preferably at the pressure in the synthesis gas generator minus normal pressure loss in the intermediate pipelines and equipment.

The effluent stream from the methanol reactor can have the following main composition in mol%: CH^OH 5-15; CO 8-25; H240-80;

C023-12; H2O 0.5-15 and (CH^O 0.05-0.6. Smaller amounts of other alcohols, aldehydes and ketones may be present.

Further cooling of the waste gas stream in air and water coolers can be effected to condense crude methanol and water. This condensate flows to a separation zone where non-condensed non-reacted gases, i.e. H 2 , CO 2 , CH 2 , N 2 and Ar are separated, e.g. by flash evaporation and is returned to the gas compressor, with the exception of a flushing flow. The crude methanol is purified by fractional distillation. Impurities including low-boiling compounds, mainly dimethyl ether and higher alcohols, can be drawn off from the distillation zone and possibly disposed of as off-gas flow or used when returning to the gas generator as part of the raw material. Dissé waste streams contain bound oxygen and thus reduce the free oxygen demand■necessary for a given level of soot production. A proportion of the product methanol can be supplied to one or both gas cleaning zones in the first and second sections as a supplementary solvent absorbent.

In the following embodiment of the present invention, methanol synthesis gas is first produced with a molar ratio of H2

and CO within the range 2-4 by the previously described method, simultaneously with the CO-rich gas stream (or preferably essentially pure carbon monoxide). Crude methanol is then produced in the previously described manner, and this is purified. Although impure methanol and CO-rich gas stream can be reacted to produce crude acetic acid, it is preferred to react purified methanol with substantially pure carbon monoxide to increase the reaction rate, and to improve selectivity.

Theoretically, one mole of carbon monoxide/mol of methanol is necessary to produce one mole of acetic acid, as shown in the following equation IV. The reaction is slightly exothermic and in practice excess carbon monoxide is required, namely approx. 22%.

Catalysts are commercially available for carbonylation reactions to produce acetic acid at high or low pressure, either as a liquid or vapor phase reaction.

High pressure carbonylation reactions for the preparation of

raw acetic acid can occur at temperatures within the range 170-320°C, e.g. 200-250°C and at a pressure within the range 15-700 atm., e.g. 150-315 atm.

Suitable commercially available high temperature carbonylation catalysts for the production of acetic acid often comprise two main compounds. A compound is a carbonyl-forming metal of the iron group, i.e. iron, cobalt or nickel in the form of a salt, e.g. acetate. The second compound is a halogen, e.g. iodine, bromine or chlorine as free halogen or as a halogen compound. For example, Col or a mixture of cobalt acetate with an iodine compound are suitable catalysts. A contact time of approx. 2-3 min, may be necessary to achieve 50-65% conversion of methanol by vapor phase reaction at high pressure. Liquid phase reaction at approx. l80°C and 258 atm. may take 3 hours, to achieve 51% con version. Water is used as a solvent or diluent and it increases the methanol conversion while simultaneously suppressing the production of methyl acetate. For example, approx. 30-40% by weight of water be present in the reaction zone.

Carbonylation reactions for the production of crude acetic acid by reacting methanol and carbon monoxide-rich gas or preferably essentially pure CO can take place at a temperature within the range 150-200°C and a pressure within the range 34-680 atm. when it comes to the liquid phase. For a 50% conversion of methanol, the reaction time is 40-200 min. A temperature in the range of 200-300°C

and a pressure within the range 1-10 atm. can be used for the vapor phase reaction.

Suitable commercially available low temperature carbonylation catalysts for the production of acetic acid include the following combinations of ingredients: (1) noble metal catalysts, (2) catalyst promoters, and (3) dispersants or carriers. Noble metal active catalysts can be chosen from the groups rhodium, palladium, platinum, iridium, osmium or ruthenium in the form of an oxide, an organometallic compound, a salt or a coordination compound, consisting of one of the aforementioned noble metals, CO,

a halide, such as a chloride, bromide or iodide, and a suitable amine, organophosfin, organoarsine or organostibine ligand. The catalyst promoter can consist of a halogen or a halogen compound. The dispersant in a liquid phase process is a solvent for the metal catalyst compound, e.g. a mixture of acetic acid and water. In vapor phase processes, the same noble metal compounds and promoters as mentioned above are dispersed on a support, e.g. alumina, activated carbon, silicon oxide or others.

For example, a typical low-pressure catalyst for liquid--2-4

phase process include 10 to 10 mol/l chlorocarbonyl-bis-triphenol--4

phosphine rhodium and 10 to 2 mol/l methyl iodide dissolved in a mixture of acetic acid and water. The ratio between halogen atoms in the promoter and noble metal atoms in the catalyst is preferably within the range 3_300.

In the low-pressure process for the production of glacial acetic acid by liquid-phase carbonylation, at least one portion<v>of the crude methanol previously produced is mixed in a reactor tank with recovered returned unreacted methanol, catalyst, catalyst promoter, acetic acid solvent for the catalyst, methyl acetate and water . The mixture is then pumped to a carbonylation reactor together with essentially pure carbon monoxide whereby the carbonylation reaction takes place at a temperature of e.g. 200°C and at a pressure of approx. 35 atm. The gaseous product is cooled and sent to

a separation zone in which unreacted gases and condensate are separated. The non-condensed gases can be washed with fresh methanol to recover entrained methanol, butyl acetate and methyl iodide for return to the reactor tank. Optionally, the remaining exhaust gas can be fed back to the gas generator or to the water-gas shift converter or vented. The liquid product from the reactor and the condensate is sent to a separation zone, e.g. distillation zone, where at a pressure of 1-3 atm. the low-boiling components, such as methanol, methyl acetate and methyl iodide, are separated and returned to the reactor tank together with recovered rhodium compound catalyst dissolved in acetic acid, and with water that can be recovered by azeotropic dehydration of acetic acid. Glacial acetic acid is also separated together with a bottom stream comprising propionic acid and heavy fractions.

Preferably, the bottom effluent stream of propionic acid and

heavy fractions as well as exhaust gases that are not flushed out are returned to the gas generator as part of the raw material. In this way, the surroundings are not polluted. Preferably, the pressure in the acetic acid synthesis zone is the same as in the partial oxidation gas generator minus usual ■ pressure loss in intermediate lines and equipment.

A more complete understanding of the invention is obtained by reference to the accompanying schematic drawings. A preferred embodiment of the method according to the invention is shown by the part of the drawing, fig. IA, which is to the left of the line A-A. Another embodiment is shown in fig. IB to the right of the line A-A. The drawings are not intended to limit the continuous process shown to the particular apparatus and substances described.

With reference to fig. IA, the unpacked, free-flowing, non-catalytic, partial oxidation synthesis gas generator 1, as described earlier, has a refractory lining 2 and a ring burner 3 arranged in the upper intake 4 along the vertical axis. The feed streams are supplied to the reaction zone 5 of the gas generator by means of the burner 3- They include an oxygen stream moving through the pipeline 6 and the central pipeline 7 in the burner, a stream of steam coming through pipelines

8 and 9 and a stream of hydrocarbon-containing fuel coming through pipelines 10 and 9. The latter two streams are mixed together

in the pipeline 9, and the mixture is then passed through the annular opening 4 in the burner 3.

The effluent stream of raw synthesis gas leaves the reaction zone

and moves through the outlet opening 15 and. directly to a spherically shaped insulated chamber 16. A part of the entrained solids can fall out of the gas flow and move through the bottom outlet 17 to the slag pot 18 via the upper inlet 19. The solids that collect in the slag pot 18 are periodically removed through the bottom outlet 20, pipeline 21, the valve 22 and the pipeline 23, or by means of a closable bin system which is not shown. When the process gas stream contains few or no entrained solids, as is the case with gaseous and certain liquid fuels, the slag pot 18 can be omitted. Optionally, the steam in pipeline 2h can be led through the intake 25 and injected into the flow of synthesis gas in the chamber 16. In this way, the mole ratio H^/CO in the process gas flow can be increased by thermal non-catalytic water-gas shift reaction.

The flow of synthesis gas is led through the outlet 26 in the chamber 16, the insulated pipeline 27 and then through the inlet 29 in the gas cooler 30 where it is cooled by indirect heat exchange with a flow of boiler feed water from pipeline 31• The boiler feed water passes through the inlet 32 and exits as steam through outlet 33 and pipeline 34. The cooled synthesis gas exits through outlet 35, pipelines 36,37, valve 38, pipeline 39 and is brought into contact with water from pipeline 40 in a suitable scrubber, e.g.

a venturi washer 4l. Remaining entrained solids, e.g. particulate carbon and ash, is then washed out of the crude

synthesis gas and moves with the water through pipeline 42 to the separation vessel 43. A mixture of solid particles and water is removed through pipeline 44 near the bottom of the vessel by 43 and is carried to a separator not shown where clarified water is separated and returned to pipelines 40 and 45. Further gas washing can e.g. is achieved by passing the flow of synthesis gas through a water spray 46 before it leaves the container 43 through pipeline 47. If no backwash is required, all or part of the process gas flow in pipeline 46 can be bypassed through pipeline 48, valve 49 and pipeline 50 .

The synthesis gas in pipeline 51 is cooled to below the dew point in the heat exchanger/52 by indirect heat exchange with cold water that enters through pipeline 53 and leaves it at pipeline 54. The cooled stream is led through pipeline 55 to the separation vessel 56 where condensed water is removed at the bottom by means of pipeline 57, and the gas stream exits through pipeline 58 at the top.

In the embodiment of the process in which the soot-free dehumidified syngas stream in pipeline 58 contains less than 5 ppm H2S and COS, valve 59 is closed, valves 60 and 61 are open, and valve 62 can be opened or closed to allow at least a portion of the gas into pipeline 58 to move to the CO^ absorption section 63 in the first gas cleaning zone 64 by means of the pipeline 65, the valve 60, the pipelines 66,67, the valve 61 and the pipeline 68. Optionally, a part of the soot-free dehumidifying gas is passed in the pipeline 58 past the first gas cleaning zone 64 and other gas cleaning zone 85

by means of pipeline 69, valve 62, pipelines 70,71, valve 72 and pipelines 73,74 and 91- Optionally, part of the soot-free dehumidifying gas flow in pipeline 70 can be removed from the system through pipeline 75, valve 76 and pipeline 77.

Pure liquid solvent absorbent enters the C02 ~ absorption zone 63 through pipeline 78 and is led down the column over a trough or packing and thereby comes into direct contact with the gas streams going up the column. Rich solvent absorbent exits section 63 saturated with C02 through conduit 79

and goes to a non-shown regeneration zone. The synthesis gas stream, which is essentially free of C02 or contains a regulated amount, exits the section 63 through the pipeline 80.

The partially purified synthesis gas stream exits the first

gas cleaning zone via the pipeline 80 and can then be split into two flows 8l and 82. At least one part of the flow of synthesis gas in the pipeline 80 is passed through pipeline 8l, the valve 83, the pipeline 84 and is then subjected to further treatment in a second gas cleaning zone 85. eventual remainder of the gas flow, 0-90 volume-%, e.g. from pipeline 74. Optionally, a share, e.g. 0-50% by volume of the partially purified synthesis gas in pipeline 87 is removed from the system through pipeline 92, valve 93 and pipeline 94.

At least one part and preferably all of the CO-rich gas or essentially pure carbon monoxide product that exits the second gas cleaning zone through pipelines 85 and 86 can be used in organic syntheses. The rest can be removed through pipeline 97, valve 98 and pipeline 99.

and pipeline 103 - In pipeline 104, at least one part of the H^-rich gas stream from pipeline 103 is mixed with all the flow of synthesis gas from pipeline 91. Thus, a purified synthesis gas product stream is produced with an increased and regulated j-^/CO mole ratio in pipeline 104 by mixing together at least one part of the H^-rich gas from pipeline 103 with at least one part of one or both of the following streams:

(a) soot-free dehumidified synthesis gas that has passed first and second gas cleaning zones 64 and 85 in pipeline 91 via pipelines 69,70,71,73,74 and 91; (b) soot-free dehumidified synthesis gas with at least one proportion of COp removed from pipeline 80 which has passed the second gas cleaning zone 85 by means of pipelines 82,87,88,90 and 91.

Any remaining Hg-rich gas from pipeline 100 can be led away through pipeline 105, valve 106 and pipeline 107 - The synthesis gas product stream in pipeline 104 has a mole ratio between Hp and CO within the range 2-12. At least a part and. preferably all of this gas flow can be passed through pipeline 108 for use in organic syntheses. Any remaining portion of the synthesis gas product stream from pipeline 104 can be passed through pipeline 109, valve 110 and pipeline 111 for other use, or returned to the gas generator either alone or mixed with other returned streams.

In another embodiment in which the soot-free dehumidified gas stream in conduit 58 contains more than 5 ppm, a desulfurization section 120 is added to the bottom of the first gas cleaning zone 64. In this case and with valves 61 and 62 closed and valves 59 and 60 open, all soot-free dehumidified synthesis gas in pipeline 58 is led to the first gas cleaning zone 64, and none of this gas flow is led around the first gas cleaning zone via pipeline 69, valve 62, pipeline 70, etc. Thus, the soot-free dehumidified gas in pipeline 58 is led through pipeline 65, the valve 60, conduits 66 and 121, valve 59, and conduit 122 to the first stage, i.e., the lower desulphurization section 120 containing troughs or packings where it is passed up through the absorption column in direct contact with a stream of liquid solvent absorbent, which flows down through the column . Clean solvent absorbent in line 123 enters section 120, absorbs HpS and COS from the synthesis gas and exits as an enriched liquid solvent absorbent via line 124. It then moves to a regenerator, not shown, to again obtain a clean liquid solvent absorbent absorbent which is returned to section 120 via pipeline 123. Desulphurised synthesis gas exits through pipeline 125 and can optionally be split into two streams. At least one part of the desulfurized synthesis gas can be passed through pipeline 126, valve 127 and pipeline 128 to an upper section 63 in the first gas cleaning zone, where at least one part of the CO2 in the gas stream is removed in the previously described manner. Any remaining part of the desulphurised gas stream in pipeline 125 is led through pipeline 129, valve 130 and pipelines 131, 132, 74 and 91. Optionally, a part of this desulphurised gas stream is removed from the system through pipeline 133, valve 134 and pipeline 135 -

A desulphurised synthesis gas stream in which at least one part of the COp has been removed leaves the first gas cleaning zone through pipeline 80. At least one part of this stream is led to the second gas cleaning zone via pipeline 8l, valve 83 and pipeline 84. Any remainder of the gas stream 80 is led past the second gas cleaning zone via pipeline 82, valve 86, pipelines 87 and 88, valve 89

and the pipelines 90 and 91- Possibly a part of this can bypass

led stream is led away through pipeline 92. A CO-rich gas or essentially pure CO product is removed through pipeline 95 in the second gas cleaning zone, and a Hp-rich gas stream is removed through pipelines 100 and 101, valve 102 and pipeline 103. A product stream of purified synthesis gas with a regulated and increased mole ratio between Hp and CO within the range 2-12 is produced by mixing in pipeline 104 at least one part of the Hp-rich gas stream, which is produced in the second gas purification zone in the pipeline 103, with at least one part of one or both of the following: (a) desulfurized synthesis gas produced in the first stage 120 in the first gas cleaning zone 64 and which passes the second stage 63 and the second gas cleaning zone 85 via the pipelines 125,129, the valve 130 and pipelines 131,132,74 and 91; (b) desulphurised synthesis gas in which at least one part of COp has been removed and which is produced in the second stage 63 in the first gas cleaning zone 64 and which passes the second gas cleaning zone 85 via the pipelines 80 and 82, the valve 86, the pipelines 87 and' 88, the valve 89 and pipelines 90 and 91.

In another embodiment shown in fig. IB, pure methanol is produced by catalytic conversion of at least one portion of pure and purified product stream of methanol synthesis gas from pipeline 108. The process steps are shown to higher for the line A-A in the drawings. The process gas stream from pipeline 108 is passed through valve 200 and pipeline 201 to a steam turbo compressor-circulator 202 together with unconverted return gas from pipeline 203. Compressed gases in pipeline 204 are then preheated in heat exchanger 205 by indirect heat exchange with hot impure metal vapor emerging from the catalytic methanol reactor 206 via pipeline 207. The preheated methanol synthesis gas stream in pipeline 208 is passed through the methanol reactor 206 where the reaction between Hp and carbon oxides takes place to produce crude methanol. After partial cooling in the heat exchanger 205, the methanol reaction products are led through pipeline 209 to the separation zone. 210, where the unreacted gases are separated from the crude methanol. The unreacted gases are passed through pipelines 215 and 203 to the return compressor 202, except for purge gas which is passed through pipeline 216, valve 217 and pipeline 218. The crude ethanol in pipeline 219 is fed to the purification zone 220 in which impurities are removed, e.g. by distillation. Dimethyl ether can be removed through pipeline 221, mixed alcohols through pipeline 222 and water through pipeline 223- Pure methanol can be withdrawn through pipelines 224 and 225, valve 226 and pipeline 227. Optionally, by-products, oxygen-containing organic compounds,

from pipelines 221, 222 and 218 is returned to the gas generator as part of the fuel and to reduce the need for free oxygen for a given level of soot production.

In yet another embodiment of the invention, a crude stream of acetic acid is produced by a low-pressure liquid-phase catalytic carbonylation reaction between pure methanol and substantially "pure" carbon monoxide, which has previously been produced. In this case, at least one part of the pure methanol in pipeline 224 led through pipeline 240, valve 24l and pipeline 242 to the reactor tank 243 and mixed with a mixture of returned substances from pipeline 244. Return stream 244 comprises a mixture of methanol, methyl acetate and methyl iodide from lines 245 and 246 and a rhodium catalyst, i.e. Rh(CO)[P(CgH^)^]pCl dissolved in a mixture of acetic acid and water from pipeline 247.

By means of the pump 248, the reactant mixture is pumped in

the tank 243 through the pipelines 249 and 250 to a vertical carbonylation reactor 251. At the same time, at least one part of the essentially pure CO gas stream in pipeline 96 is led to the carbonylation reactor 251 via the valve 255, the pipeline 256, a possible steam turbo compressor 257 and the pipeline 258 In the reactor 251, methanol and CO react and form acetic acid. A gas stream is carried out overhead through pre-pipe 259, cooled in heat exchanger 260 and carried through pipe 261 to separator 262. Non-condensed gases in pipe 263 are washed with fresh methanol in a tower not shown to recover entrained methanol, methyl acetate and methyl iodide for return to the reactor tank 24 3. Remaining waste gas from the scrubber can be returned to the gas generator or vented.

The liquid product from the reactor in pipeline 264 and the condensate from pipeline 265 are passed through pipeline 270

to the separation zone 271 - For example during distillation, low-boiling components comprising a mixture of methanol, methyl acetate and methyl iodide can be separated, and these exit via pipeline 245; water is removed through conduit 272; recovered rhodium compound catalyst dissolved in acetic acid is removed through pipe-

ning 2^7; and impure acetic acid is removed through pipeline 273 and fed to the separation zone 274. Glacial acetic acid is recovered as a distillate from pipeline 275. Propionic acid and heavier components exit through pipeline 276 and can be returned to the gas generator as part of the fuel.

Example

The following example illustrates an embodiment of the method according to the invention for the simultaneous and continuous production of a stream of methanol synthesis gas and a stream of substantially pure. carbon monoxide. The example is not limiting for the scope of the invention. Reference is made to the drawing.

The feedstock for a non-catalytic free-flowing partial oxidation gas generator comprises 20.99 million standard feet^

per day of natural gas and 13.94 million standard ft^/day of essentially pure oxygen (99 mol-% Op). The composition of the natural gas is as follows: CH^87.62; CpHg 7.96; C 2 H 2 0.61; COp 1.25 and Np 2.56. No HpO is supplied to the gas generator.

65.01 million standard ft^/day of raw synthesis gas leaves the reaction zone of the gas generator at a temperature of 1430°C and at a pressure of 64.72 atm. The amount in million standard feet -x/day (MMSCF/day) and the composition-in mole-% of synthesis crude gas leaving the reaction zone at reference numeral 15 in the drawing is shown in column 1 of the table that follows. Because no solids are entrained in the gas flow from the gas generator, the slag pot 18 and the carbon washing zone comprising 41 and 43 in FIG. IA is omitted. Furthermore, no water-gas exchange is necessary in the present method to increase the mole ratio between Hp and CO.

The amount and composition of the dehumidified gas stream leaving the gas-liquid separator 56 via pipeline 58 is shown in column 2 of the table. The gas flow in pipeline 58 is then separated into two flows. A flow in pipeline 69 is led past the first gas cleaning zone 64. The other flow in pipeline 65 is led to the first gas cleaning zone. The quantity and composition of the gas streams 69 and 65 are shown in columns 3 and 4 of the table.

Essentially all COp is separated in the first gas cleaning zone. The amount and composition of the COp residual gas that is recovered in

a solvent regenerator not shown, is reproduced in column 5 of the table.

The purified synthesis gas stream leaving the first gas purification zone through conduit 80 is shown in column 6 of the table. This entire gas stream is supplied to a second gas cleaning zone, where

it is divided into a CO-rich product gas stream in pipeline 96 and a Hp-rich gas stream in pipeline 100. Amounts and compositions of these gas streams are shown in columns 7 and 8 of the table.

The product gas for the methanol synthesis is then produced by mixing in pipeline 104 all the soot-free dehumidified gas stream that passes the first gas cleaning zone via pipeline 69, valve 62, pipelines 70 and 71, valve 72 and pipelines 73,74 and 91 with all Hp- rich gas from pipelines 100 and 101, valve 102 and pipeline 103- Quantity and composition for this methanol synthesis product gas stream in pipeline 108 is shown in column 9 of the table. This is the suitable gas composition for mixing with unconverted return gas from a catalytic methanol converter to obtain a feed gas for conversion to crude methanol. Crude methanol can be produced by distillation and reacted in a catalytic carbonylation reactor with at least one portion of the stream of substantially pure carbon monoxide from stream 96 to obtain crude acetic acid in the manner described above in connection with the drawing's fig. IB. Glacial vinegar can then be produced by purification.

The method according to the invention is described generally and via examples with reference to hydrocarbon-containing fuel, synthesis gas and Hp-rich gas of special composition, but only for clarification and illustration. It will be clear to the person skilled in the art that variations and modifications can be made without

go beyond the scope of the invention.

Claims (20)

1. Method for the simultaneous production of a product stream of purified synthesis gas and a product stream of CO-rich gas, characterized by the following steps: (1) reaction of a hydrocarbon-containing raw material with a free oxygen-containing gas, possibly in the presence of a temperature moderator, in the reaction zone of a free-flowing non-catalytic partial oxidation gas generator at a temperature within the range 704-871°C and at a pressure within the range 1-250 atm. to obtain a waste gas stream comprising H"2 , CO, HpO, COp and possibly at least one substance from the group HpS, COS, CH^ , N2 , Ar, and solid particles; (2) removal from said waste gas stream from step (1) of a proportion of said solid particles, if these are present, cooling of the gas stream by indirect heat exchange in a separate heat exchange zone, removal from the gas stream of remaining entrained solid particles present and dehumidification of the gas stream; (3) supplying at least one part of the clean dehumidified gas stream from (2) to a first gas cleaning zone and passing past said first gas cleaning zone of any remaining portion; removal from the gas stream in the first gas cleaning zone of HpS, COS and at least one proportion of CO^ present; (4) supply of partially purified gas from the first gas purification zone -in (3) to a second gas purification zone and passage past said second gas purification zone of at least one part of the possibly present residue and removal from said second gas purification zone of said product stream of CO- rich gas and a separate stream of Hp-rich gas; and (5) mixing at least one part of the Hp-rich gas from (4) with at least one part of at least one of the following:■ (a) gas treated in the first gas cleaning zone and passed to the second gas cleaning zone in (4); (b) soot-free dehumidified gas passed through the first gas cleaning zone in (3); for the production of said product stream of purified synthesis gas with regulated mole ratio Hp/CO. 2. Method according to claim 1, characterized in that the waste gas stream from the reaction zone in step (1) and synthesis gas from the first gas purification zone in step (3) have a mole ratio Hp/CO within the range 0.5-1'.93 and that the product stream of purified synthesis gas from step (5) has a mole ratio Hp/CO within the range 2-12. 3. Method according to claim 1 or claim 2, characterized in that from approx. 10-100 volume-? of the clean dehumidified gas flow from step (2) is supplied to the aforementioned first gas cleaning zone in step (3)- 4. Method according to any one of claims 1-3" characterized in that 10-90 volume-? of the synthesis gas from the first gas purification zone in step (3) is supplied to the second gas purification zone in step (4), and that the remaining proportion of said synthesis gas comprising 90-10 volume-? is passed past the second gas cleaning zone in step (4) and mixed with said gas in step (5) to obtain said stream of product gas. 5. Method according to any one of the preceding claims, characterized by the further step of introducing supplementary steam to the waste gas stream from (1) in an amount of approx. 01-2.5 mol of supplementary steam/mol of waste gas stream, and reaction in a separate free-flowing non-packed reaction zone, at a pressure substantially equal to that of the synthesis gas generator minus normal pressure loss in the pipelines and at a temperature of at least 8l5°C, of HpO and a proportion of CO in the waste gas stream from (1) to increase the mole ratio Hp/CO. 6. Method according to any one of the preceding claims, characterized in that a proportion of COp from the first gas cleaning zone is returned to the gas generator. 7. Method according to any one of the preceding claims, characterized in that the partially purified gas from the first gas purification zone is brought into contact with a sulphur-free liquefied CH^ -rich gas stream in a separation column in said second gas purification zone, and that the bottom stream from said separation column is fed to the partial oxidation gas generator in step (1) as at least part of the raw material. 8. Method according to any one of the preceding claims, characterized in that the product stream of purified synthesis gas is methanol synthesis gas with a Hp/CO molar ratio within the range 2-4. 9. Method according to any one of the preceding claims, characterized in that said product stream of CO-rich gas from step (4) is essentially clean. CO containing 90-99.5 mol-? Co.. 10. Method according to any one of the preceding claims, characterized by the further step of reacting at least one portion of said methanol synthesis gas in the presence of a methanol catalyst in a methanol synthesis zone at a temperature within the range 204-400°C and at a pressure within the range 40-350 atm. for obtaining crude methanol and purifying said crude methanol to obtain essentially pure methanol and, as a by-product, oxygen-containing organic substances. 11. ' Method according to claim 10, characterized in that at least one part of said by-product oxygen-containing organic substances is returned to the synthesis gas generator as a proportion of hydrocarbon-containing fuel. 12. Method according to claim 10 or 11, characterized in that at least one proportion of said essentially pure methanol is used in said first gas purification zone to absorb gaseous impurities from the gas streams. 13. Method according to any one of claims 10-12, where the CO-rich gas in step (4) is essentially pure CO, characterized by reacting at least one part of said essentially pure methanol with at least one part of said substantially pure carbon monoxide in the presence of a carbonylation catalyst in an acetic acid synthesis zone at a temperature within the range of 150-320°C and at a pressure within the range of 1-700 atm. for obtaining impure acetic acid, and by purifying said impure acetic acid to obtain substantially pure acetic acid and by-product oxygen-containing organic substances. 14. Method according to claim 13, characterized in that at least one part of said by-product oxygen-containing organic substances is returned to said synthesis gas generator as part of part of the carbonaceous fuel. 15- Method according to any one of claims 10-14, characterized in that the hydrocarbon-containing raw material in step (1) is reacted as mentioned above with essentially pure oxygen to obtain a waste gas stream comprising Hp, CO, HpO, COp and at least one more substance, from the group CH^, Np, Ar, particulate carbon and ash; and that the previously mentioned steps (3)-(5) include splitting up soot-free, dehumidified gas flow from said step (2) to a first and a second gas flow in which said first separated gas flow comprises 10-90 volume-? of the waste gas stream from (2), and said second separated gas stream comprises the remainder; purification of said first separated gas stream in a first gas purification zone and separation from this of at least one proportion of CO^ ; splitting the gas flow from the first gas cleaning zone into a third and fourth gas flow with said third gas flow comprising 10-100 volume-? of said gas flow obtained from <v> the first gas cleaning zone, and said fourth gas stream containing the remainder, if any, and supplying all of said third gas stream to a second gas cleaning zone, removing a stream of CO-rich gas and a stream of Hp-rich gas from said second gas cleaning zone; mixing of at least one part of said second gas stream, at least one part of said Hp-rich gas stream and at least one part of said fourth gas stream, if present, to obtain a stream of methane synthesis gas. 16. Method according to claim 15, characterized in that the molar ratio Hp/^CO + 3CO2 ) in said methanol synthesis gas lies within the approximate range 1.01-1.05- 17. Method according to claims 13 and 16, characterized in that at least one part of said pure acetic acid is returned to said second gas cleaning zone in order to cause CO separation from said third gas stream. 18. Method according to any one of claims 1-14, characterized in that the previously mentioned steps (3)-(5) comprise: (3) desulfurizing the gas stream from step (2) in the first stage of a two-stage first gas cleaning zone, supplying at least one portion of the sulfurized gas stream from the first stage to the second stage in said first gas cleaning zone and removing at least one proportion of C02 ; and passing past said second stage of the possible remainder of said desulfurized gas from the first stage in said first gas cleaning zone; (4) supply of at least one part of the gas stream from the second stage in said first gas cleaning zone to a second gas cleaning zone when there is a flow of desulphurised gas from the first stage which is passed by said second stage, or supply to said second gas cleaning zone of a proportion of the gas stream leaving the second stage in said first gas cleaning zone when there is no desulphurised gas stream passing said second stage; and passing past said second gas cleaning zone of the possible remainder of said gas stream leaving the second stage in said first gas cleaning zone; and removing from said second gas cleaning zone a product stream of CO-rich gas and a stream of Hp-rich gas; and (5) mixing at least one portion of the Hp-rich gas stream from (4) with at least one portion of at least one of the following: (a) desulfurized gas stream that has been passed to the second stage in the first gas cleaning zone in (3); (b) desulfurized gas stream with at least one proportion of CO^ removed which leaves the second stage of the first gas cleaning zone and which is passed to the second gas cleaning zone in (4); for producing said product stream of purified synthesis gas with a regulated mole ratio H2 /CO.- 19. Method according to any one of claims 1-14, characterized in that the previously mentioned steps (3)-(5) comprise: (3) desulfurization of the gas stream from step (2) and removal of at least one proportion of COp by direct contact with a liquid solvent absorbent in a first gas cleaning zone; (4) supplying a portion of the process gas stream from (3) to a second gas cleaning zone' and passing past the second gas cleaning zone the remainder of said desulphurized gas stream with at least one portion of CO^ removed from (3); removing from said second gas cleaning zone a product stream of CO-rich gas and a stream of Hp-rich gas; and (5) mixing to obtain said product stream of purified synthesis gas with a regulated molar ratio Hp/CO of at least one part of said Hp-rich gas stream with at least one part of remaining desulfurized gas with at least one part of COp removed which is passed to the second gas cleaning zone in stages (4). 20. Method according to any one of claims 1-14 in which an essentially sulphur-free hydrocarbon-containing raw material is used, characterized in that steps (3)-(5) comprise: (3) supply of at least one part of the dehumidified gas stream from (2) to a first gas cleaning zone and passing past said first gas cleaning zone with the possible remainder of said dehumidified gas from (2); and removal from the process gas stream in said first gas cleaning zone of at least one proportion of CO^ present; (4) supply of at least one part of the gas flow leaving the first gas cleaning zone to a second gas cleaning zone when there is a flow of soot-free dehumidified gas which is passed by said first gas cleaning zone, or supply of part of the gas flow leaving the first gas cleaning zone to the second gas cleaning zone when there is no flow of soot-free dehumidified gas passing through the first gas cleaning zone, and passing past the second gas cleaning zone any remainder of the gas stream leaving the first gas cleaning zone; and removing from said second gas cleaning zone a product stream of CO-rich gas and a stream of H^-rich gas; and (5) mixing at least one portion of the Hp-rich gas from (4) with at least one portion of at least one of the following: (a) dehumidified gas stream from (2) which is passed through the first gas cleaning zone in (3); (b) partially purified synthesis gas from the first gas purification zone with at least one proportion of CO^ removed and which is passed to the second gas purification zone in (3); and producing said product stream of purified synthesis gas with a regulated mole ratio Hp/CO.