DE3144266A1 - "METHOD FOR PRODUCING SYNTHESIS GAS" - Google Patents

Description

Dr. Gerhard Schupfner patent attorney

3U42B6

Karlstrasse 5

2110 Buchholz / Nordheide

November 06, 1981

T-030 81 DE S / KB D 76,569-F (RK)

TEXACO DEVELOPMENT CORPORATION

2000 WESTCHESTER AVENUE WHITE PLAINS, N.Y. 10650

UNITED STATES.

Process for the production of synthesis gas

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Dr. Gerhard Schupfner »Texaco Development Corp. Patent attorney T-03Ü 81 DE

D 76,569-F (RK)

Process for the production of synthesis gas

The invention relates to a method of manufacture of carbon monoxide and hydrogen, d. H. Synthesis gas, from carbonaceous solid fuels through partial oxidation with an oxygen-containing gas and to remove the ashes produced in the process. In particular, the invention relates to the gasification of carbonaceous solid fuels at overpressure in a non-catalytic flow reactor, with a slurry of solid fuel and water in the liquid phase of a reaction zone, which is kept at an autogenous temperature in the range of approx. 982-1760 C. is supplied and is reacted there with oxygen.

The production of carbon monoxide and hydrogen or synthesis gas through non-catalytic conversion of carbonaceous solid fuels with air, oxygen-rich air or relatively pure oxygen is disclosed in U.S. Patent 3,544,291 specified. The partial oxidation of solid fuels such as coal or petroleum coke is a very economical process for generating large quantities of synthesis gas. In the flow gas generator or partial oxidation reactor Solid fuel with an oxygen-containing gas in one closed, compact, coreless reaction zone

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an autogenous temperature in the range of approx. 982-1760 ⁰ C, preferably 1093-1537 ⁰ C, implemented.

Usually used in the gasification of fuels such as Coal or coke the finely divided fuel of a partial oxidation. subjected to the generation of a product gas, the carbon monoxide and hydrogen as well as small amounts of carbon dioxide and methane and, if used, sulfur contains, contains hydrogen sulphide and carbonyl sulphide. However, because not enough oxygen is introduced into the gasification zone to remove the carbon contained in the fuel to burn completely, d. H. about the total carbon content of the fuel to convert into carbon dioxide, some of the solid fuel passes through the gasification zone without to be converted into a carbon oxide. Further, if the feed to the gasification zone contains ash, contains the product gas also has ash particles.

Usually it is desirable to have these particulate matter out the product gas. If z. B. the inherent heat of the gas can be recovered through indirect heat exchange it may be advisable to remove the solid particles from the gas before it is introduced into a heat exchanger is to prevent the particles from collecting on the walls or heat transfer surfaces of the heat exchanger and a resultant impairment of fluid flow as well as to avoid heat transfer. at

In one such process, the hot particles are impinged on the water surface in a quench zone brought so that they are quenched and wetted, causing them to be separated from the gas stream and into the water be convicted. In another method, if the product gas is used for hydrogen generation, the gas is used is usually quenched by introducing it into a sub-surface quenching zone with the solid particles retained in the water and the substantially particle-free water-saturated gas then undergoes catalytic conversion subject. A combination of these methods is given in U.S. Patent 3,998,609. To an accumulation of solids and / or avoiding contamination in the quenching water is either a periodic or a continuous one Part of this water is withdrawn and used to maintain a constant liquid level in the quenching zone replaced by water, which is preferably sewage water, that is fed from a settling zone to which the amount of water withdrawn is recycled.

If the gas generator is operated at increased pressure, the solid particles must be removed from the system, oY. ^ E that the pressure is released, and this can be done by introducing the particles into a lock hopper and discharging them from the system. Since the lock

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funnel is regulated by shut-off devices, the inlet has of the lock funnel in comparison with the gas generator normally has a relatively small diameter, so that immediately above the lock funnel there is a section with a downwardly decreasing cross-sectional area is.

From material balances it can now and then be seen that, relative to the amount fed to the gas generator and the amount of gas generated, an amount of solid particles that is too small is withdrawn through the lock funnel. If this condition lasts for some time, it will be necessary to Shut down the system and remove the blockage, usually on the narrowed section of the facility occurs above the upper lock funnel shut-off device.

The object of the invention is to provide a method for producing a substantially particle-free carbon monoxide and hydrogen-containing gas under positive pressure, with the removal of ash and unreacted solid fuel particles from a gasification system for ash-containing fuels is to be improved.

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In the process of the present invention for producing substantially particulate-free synthesis gas an ash-containing fuel is subjected to partial oxidation under excess pressure to generate a stream of synthesis gas from carbon monoxide and hydrogen, the hot one Contains particles of ash and unreacted fuel, causing the hot particles to come into contact are cooled with water in a quench zone, the particles for settling through the quench zone in a water-filled settling zone and a quenched one Particulate-containing water flow is maintained from the quench zone into the settling zone.

The feedstock for the specified process is any ash containing carbonaceous fuel such as coal, subbituminous coal, lignite, coke, biomass and the like. Usually this fuel is solid, it can but also fuels that are liquid at higher temperatures, e.g. B. coal liquefaction residues can be used. To be considered as containing ash, the Fuel have an ash content of at least approx. 1% by weight. When using at higher temperature melts, it can be preheated and introduced as a liquid into the dxO gasification zone. When the fuel however, it should be solid even at higher temperatures are ground to a particle size of less than 6.35 mm, preferably to a particle size such that

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at least 95 % pass through a sieve with a mesh size of 1. Al mm. The fuel is then injected into the gasification zone, in which it is subjected to partial oxidation with a gas such as air, oxygen-rich air or essentially pure oxygen, ie oxygen with a purity of at least about 95 % . The solid fuel can be introduced into the partial oxidation zone as a slurry in a liquid such as water or oil or as a suspension in a gaseous or vaporous medium such as water vapor, carbon dioxide or mixtures thereof. Water or steam can also be introduced into the gasification or partial oxidation zone as a temperature moderator if the fuel feed is a liquid or a slurry of solids in oil or another combustible liquid.

In the gas generation zone, the fuel is subjected to partial oxidation at an autogenously maintained temperature between approx. 982 and 1760 ° C., preferably between approx. 1093 and 1537 ^° C. The pressure in the gas generation zone can be in the range between approx. 3.7 and 208 bar, preferably between approx. 5 and 173 bar. The oxygen is introduced into the gasification zone with an oxygen / carbon atomic ratio between about 0.7 and 1.6, preferably between 0.8 and 1.2. If the fuel is solid and is introduced into the gasification zone as a slurry in water, the slurry should be less than approx.

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Contain 50% by weight of water, as it has a higher water content adversely affects the thermal efficiency of the reaction.

In a process for recovering heat from by The partial oxidation of synthesis gas produced by ash-containing fuel is down the gas from the gas generator by means of a radiation cooling zone together with the ash particles carried along and other existing unreacted Fuel particles out. Then the gas is deflected from its original path through the radiant cooling zone and - according to a preferred embodiment - more or less ι led up to a convection cooling zone, where it goes up in indirect heat exchange with a coolant, e.g. B. water is performed. The solid particles move on their path and arrive with water in a quenching zone at the lower end of the radiation cooling zone in contact where they are wetted and settle in the water. Then the solid particles descend through the upper shut-off device of a lock funnel, which can also be viewed as a settling zone, where it is collected will. Since the upper shut-off element of the lock funnel is mostly kept in the open position, the lock funnel is filled with water. The upper shut-off device of the lock funnel is used to remove the solid particles periodically closed, and a shut-off device arranged at the lower end of the lock funnel is opened,

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so that the water and particulate matter out of the system can be deducted. Then the lower shut-off device of the lock funnel, the lock funnel, is closed is filled with water, pressurized and the upper shut-off valve opened, so that more ash or Slag can settle and is collected in the lock funnel. Alternatively and preferably, the lock funnel, to prevent corrosion, kept filled with water while the accumulated solids are drained off. this takes place by introducing water, preferably at the top of the lock funnel, while the upper shut-off element between the lock funnel and the quenching chamber is closed by a separate inlet with the the same throughput with which the contents of the lock funnel are drawn off through the opened lower shut-off device. In this way, the lock funnel is always filled with water and no air can enter the lock funnel.

In order to prevent a blockage above the upper shut-off element of the lock funnel, according to one embodiment the invention circulated water from outside the lock funnel to the quenching zone, so that a water flow containing entrained particles descends through the upper shut-off device of the lock funnel flows. This is achieved by drawing water from or near the top of the lock hopper and

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returned either directly or indirectly to the quenching zone. When a modification of the shut-off devices and the piping is carried out, that for the withdrawal of water, which is returned to the quenching zone, The opening used must be the same opening used for introducing water during the emptying cycle of the Lock funnel is used. Is advantageous the outlet for the withdrawn water from the downward flowing water stream containing quenched particles, separated by a baffle so that only a minimum of particles is returned to the quenching zone. To this A continuous stream of water flows downwards from the quenching zone to the settling zone and supports the transfer the solids from the quenching zone into the settling zone or the lock funnel, so that no blockage arises. However, this current is interrupted when the lock hopper cycle for the discharge of the accumulated Solid particles begin.

The water throughput from the quenching zone into the settling zone or the lock funnel is not critical, it should however, higher than the throughput of the upwardly directed water flow displaced by the downwardly directed particles will be, if no circulation were foreseen. In practice the downdraft flow rate should be at least 0.55 m / min, preferably at least 0.91 m / min.

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Since both the inlet and the outlet of the lock funnel can be regulated by shut-off devices, the Connection between the outlet of the quenching zone and the inlet to the lock funnel a section with steady decreasing cross-sectional area. To prevent larger ash or slag particles from this section or block the shut-off device, it is advantageous to provide a grinder above the narrowed section.

After the synthesis gas has left the convection room, it can be used in any suitable manner, e.g. B. for the synthesis of organic compounds, the water. Material production or as fuel.

The radiation cooling zone was explained as a downflow zone and the convection cooling zone as an ascending flow zone, it however, by modifying the device, it is possible to pass the gas through each section of the system in either of the two To let directions flow.

Another heat recovery process provides that the oxygen-containing gas and fuel in the gas generator or the partial oxidation zone can be introduced at its upper end and passed "downwards" through the gas generator. A quench zone containing water is provided at the bottom of the gas generator; before the hot product gas however reaches the quench zone, it becomes more or less

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deflected upwards into a radiation cooling zone, while the solid particles continue to move into the shut-off water move where they are wetted and through the water located there into a lock funnel or a settling zone get where they settle. The diverted gas is then, in one case, up through a radiant cooling zone and then down through a convection zone, or in another case down through a radiant cooling zone and passed upwards through a convection cooling zone or either upwards or downwards through both cooling zones.

About the movement of the solid particles out of the target zone To accelerate into the settling zone, water is in turn circulated from the settling zone to the quenching zone, so that a steady downward flow from the quenching zone through the upper lock funnel shut-off device to the settling zone results.

Water circulating outside the settling zone can enter the quenching zone above the surface of the water inside it Water introduced and sprayed on the water surface, so that floating particles are wetted and som * t sink; the water can also be introduced below the surface of the quenching water and directed upwards to the surface of the water to reduce the turbulence in the quenching

zone to be strengthened, or directed downwards, so that the strength of the water flow to the lock funnel increases and reducing the risk of slag or ash particles bridging the narrow inlet section in form the lock hopper, which would block the flow of solids into the lock hopper; it is also possible to use a combination of these three water flows. When the circulating water is below the Surface of the quenching water introduced in an upward direction a flotation effect is created by which the high carbon particles are separated from the denser ones high ash particles are separated; advantageously the quenching then takes place near the surface of the quench water to remove water with a higher proportion of high carbon particles.

According to a further embodiment of the invention Water is not circulated from the lock funnel to the quenching zone, but is instead drawn from the lock funnel withdrawn and combined with the quench blow-off and transferred to a settling tank in which the solid particles settle out of the water, which then as additional quenching water either returned to the quenching zone or for the preparation of further feed slurry is used. To compensate for the increased flow of water to the sedimentation tank, the flow of additional quenching water is used in the quenching zone according to the amount of water withdrawn from the lock funnel. To this

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Way, a stream of water from the quenching zone passes through Maintain the upper shut-off device of the lock funnel in the lock funnel.

Exemplary of the effectiveness of the method according to the invention is a series of high pressure coal gasification attempts in which the gas generator was a No. 9 Kentucky coal. All experiments were carried out under essentially identical working conditions. The first attempt lasted 26.6 hours, after which a shutdown had to take place because the slag had formed a bridge above the upper shut-off device of the lock funnel. After the slag bridge had been removed, the gasification was resumed, but the renewed formation of a slag bridge meant that the second attempt had to be terminated after 18 hours. The third attempt lasted 20.5 hours, and the fourth attempt lasted almost 20 hours, after which a shutdown had to take place in each case for the same reason. Before the fifth attempt, a blow-off system was installed to remove water from the upper part of the lock funnel and feed it into the quench blow-off at a constant speed. The downward flow of water from the quenching zone through the upper shut-off element of the SuJnleus funnel into the same with a throughput of 1.28 m / min was successful in that the fifth attempt ran for 42.5 hours and was not terminated by blocking with slag, but for mechanical reasons had to become. To

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The system was started up and the error rectified ran with success for 66.8 hours without interruption, after which the experiment was terminated voluntarily. Then the system ran uninterrupted 112 hours.

From the above explanations it can be seen that it was necessary before the application of the invention, the plant after Switch off approx. 20-25 h operating time due to blockage. After installing a system through which water from the The quenching zone could flow through the upper shut-off device of the lock hopper and into the lock hopper, there was no more clogging or no more bridging due to slag in the system, and the system ran more than 200 hours continuously.

The invention was explained with reference to gasification plants in which the synthesis gas is in the quenching water is introduced below its surface, so that not only the solid particles of ash and unreacted Fuel but also the syngas itself can be quenched; however, the method is also advantageous Applicable in a gasification plant in which the water in the quenching zone is more or less calmed.

Claims (12)

Dr. Gerhard Schupfner Texaco Development Corp. Patent attorney T-030 81 DE D 76,569-F (RK) claims 1. A process for the production of synthesis gas substantially free of particulate matter, in which an ash-containing fuel is subjected to partial oxidation under excess pressure, with a synthesis gas stream generated from carbon monoxide and hydrogen, the hot particles of ash and unreacted Contains fuel, the hot particles are cooled by contacting them with water in a quenching zone and the quenched particles through the quench zone to settle in a water-filled settling zone to be brought, characterized in that a stream of water containing quenched particles from the quench zone to the settling zone 2. The method according to claim 1,
characterized, that the water flow is maintained by returning water from the settling to the quenching zone. 3. The method according to claim 2, characterized in that the circulating water in the quenching zone above the surface of the water it contains. 4. The method according to claim 2, characterized in that that the circulating water is introduced into the quenching zone below the surface of the water contained therein. 5. The method according to any one of the preceding claims, characterized in, that the gases leaving the partial oxidation zone and entrained particles flow through a radiation cooling zone before the particles reach the quench zone. 6. The method according to any one of claims 1 to 4-, characterized in that the gases are diverted to a radiation cooling zone, while the particles continue their orbit into the water of a quench zone. 7. The method according to claim 5, characterized in that the gas flow path is downward through the radiation cooling zone runs. ■ '.- ■ ^: '.!, ^; Γ- .. 3U4266 8. The method according to claim 6, characterized in that the gas flow path is upward through the radiation cooling zone runs. 9. The method according to any one of the preceding claims, characterized in, that the settling zone is kept filled with water while the particles are removed therefrom. 10. The method according to any one of the preceding claims, characterized in that water withdrawn from the settling zone with quenching zone blow-off water combined, the mixture settled and water recovered from the settling zone to System is returned. 11. The method according to claim 10, characterized in that that the settling water is returned to the quenching zone. 12. The method according to claim 10, characterized in that the settling water with the ash-containing feedstock in The partial oxidation zone is introduced.