AU2006201144A1

AU2006201144A1 - Method and device for producing synthesis gases by partial oxidation of slurries made from fuels containing ash with partial quenching and waste heat recovery

Info

Publication number: AU2006201144A1
Application number: AU2006201144A
Authority: AU
Inventors: Torsten Bergt; Friedemann Mehlhose; Manfred Schingnitz
Original assignee: Future Energy GmbH
Current assignee: Future Energy GmbH
Priority date: 2005-09-07
Filing date: 2006-03-20
Publication date: 2007-03-22
Also published as: CA2537787A1; ZA200607265B; US20070051043A1; DE102005042640A1; DE202005021662U1; CN1928028A

Description

AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicants: Future Energy GmbH, and Dr. Manfred Schingnitz Invention Title: METHOD AND DEVICE FOR PRODUCING SYNTHESIS GASES BY PARTIAL OXIDATION OF SLURRIES MADE FROM FUELS CONTAINING ASH WITH PARTIAL QUENCHING AND WASTE HEAT

RECOVERY

The following statement is a full description of this invention, including the best method of performing it known to Us: -2- Method and device for producing synthesis gases by partial oxidation of slurries made from fuels containing ash with partial quenching and waste heat recovery Technical Field The present invention relates to a gasification method and a device for implementing the method.

Background The autothermic flue stream gasification of solid, liquid, and gaseous fuels has been known in the technology of gas production for years. The ratio of fuel to gasification medium containing oxygen is chosen so that higher carbon compounds are completely cracked for reasons of synthesis gas quality into synthesis gas components such as CO and H 2 and the inorganic components are discharged as molten slag; see J.

Carl, P. Fritz, NOELL-KONVERSIONSVERFAHREN, EF-Verlag fir Energie- und Umwelttechnik GmbH, 1996, p. 33 and p. 73.

According to various systems used in industry, gasification gas and molten slags can be discharged together from the reaction chamber of the gasification device, as shown in DE 197 131 Al. Either systems with refractory linings or cooled systems are used for the inner confinement S:P59910 -3of the reaction chamber structure of the gasification system; see DE 4446 803 Al.

EP 0677 567 B1l and WO 96/17904 show a method in which the gasification chamber is confined by a refractory lining.

This has the drawback that the refractory masonry is loosened by the liquid slag formed during gasification, which leads to rapid wear and high repair costs. This wear process increases with increasing ash content. Thus such gasification systems have a limited service life before replacing the lining. Also, the gasification temperature and the ash content of the fuel are limited. Feeding in the fuel as a coal-water slurry causes considerable losses of efficiency see C. Higman and M. van der Burgt, "Gasification", Verlag ELSEVIER, USA, 2003 which can be prevented or reduced by using oil as a carrier medium or by preheating the coal-water slurry. A quenching or cooling system is also described, with which the hot gasification gas and the liquid slag are carried off together through a conduit that begins at the bottom of the reaction chamber, and are fed into a water bath. This joint discharge of gasification gas and slag can lead to plugging of the conduit and thus to limitation of availability.

DE 3534015 Al shows a method in which the gasification media, powdered coal and oxidizing medium containing oxygen, S:P59910 are introduced into the reaction chamber through multiple burners in such a way that the flames are mutually deflected.

The gasification gas loaded with powdered dust flows upward and the slag flows downward into a slag-cooling system. As a rule, there is a device above the gasification chamber for indirect cooling utilizing the waste heat. However, because of entrained liquid slag particles there is the danger of deposition and coating of heat exchanger surfaces, which hinders heat transfer and may lead to plugging of the pipe system and/or erosion. The danger of plugging is counteracted by cooling the hot crude gas with a circulated cooling gas.

Ch. Higman and M. van der Burgt in "Gasification", page 124, Verlag Elsevier 2003, describe a method in which the hot gasification gas leaves the gasifier together with the liquid slag and directly enters a waste heat boiler positioned perpendicularly below it, in which the crude gas and the slag are cooled with utilization of the waste heat to produce steam. The slag is collected in a water bath, while the cooled crude gas leaves the waste heat boiler from the side.

A series of drawbacks detract from the advantage of waste heat recovery by this system. To be mentioned here in particular is the formation of deposits on the heat exchanger tubes, which lead to hindrance of heat transfer and to corrosion and erosion, and thus to lack of availability.

S:P59910 CN 200 4200 200 7.1 describes a "Solid Pulverized Fuel Gasifier", in which the powdered coal is fed in pneumatically and gasification gas and liquefied slag are introduced into a water bath through a central pipe for further cooling. This central discharge in the central pipe mentioned is susceptible to plugging that interferes with the overall operation, and reduces the availability of the entire system.

Summary of the Invention In a first aspect, the present invention provides a method for the gasification of fuels such as bituminous coals and cokes such as bituminous, lignite, biomass, and petroleum coke in the flue stream with an oxidizing medium containing free oxygen, by partial oxidation at pressures between atmospheric pressure and 100 bar and at temperatures between 1,200 and 1,900 degrees, consisting of the process steps of slurry preparation and infeed, gasification by partial oxidation in a reactor with cooled reactor chamber contour, partial quenching, crude gas scrubbing and partial condensation, wherein the crude gas scrubbing and partial condensation can be replaced by dry mechanical dust removal operating above the condensation point, wherein: S:P59910 a pulverized fuel with a grain size 200 gm, preferably 100 lim, is slurried with water with added surfactant in a special system, to obtain a fuel-in-water slurry with a solids concentration of 40-70 and is brought to the gasification pressure of 100 bar by pumping, for which the slurry can be preheated to temperatures up to 400 OC, the slurry fed to the reactor through a supply pipe together with an oxidizing medium containing free oxygen is subjected to partial oxidation in the reaction chamber, whose contour is confined by a cooling shield, with the ash of the fuel being melted and transferred through the discharge device to the quenching chamber of the quenching cooler along with the hot gasification gas, the partial quenching takes place with cooling of the crude gas to temperatures between 700 and 1,100 °C, the partially quenched crude gas is cooled in a waste heat boiler to temperatures between 150 and 400 OC with generation of steam, the cooled crude gas is then subjected to a crude gas scrubber and partial condensation, or to dry mechanical S:P59910 -7dust separation by centrifugal force or filtration, to separate entrained dust, the cooled crude gas freed of dust is then sent to further treatment steps such as crude gas conversion or desulfurization.

To achieve long operating times, the pressurized jacket of the gasification reactor has to be protected reliably against the action of crude gas and against the high gasification temperatures of 1200 1900 0 C. This is done by confining the reaction or gasification chamber with a cooled tubular shield that is hung in the pressurized jacket. The annular gap between tubular shield and pressurized jacket is flushed.

The fuel as a slurry is brought to the gasification pressure by pump transport and is fed to the head of the reactor through burners. One or more fuels or varieties of coal can be gasified at the same time. The crude gas leaves the gasification chamber together with the liquefied slag at the bottom of the reactor and is then partially cooled to 700 OC to 1100 OC by injecting water, and is freed of entrained fines after recovering the waste heat. The scrubbed crude gas is then fed to further treatment steps.

S:P59910 -8- In one embodiment the method consists of the process steps of slurry preparation, fuel infeed, gasification reaction, partial quenching, gas scrubbing, and partial condensation, wherein gas scrubbing and partial condensation can be replaced by mechanical dust separation, to produce gases containing CO and H 2 by partial oxidation of powdered fuels containing ash with a gasification medium containing free oxygen, at high temperatures and elevated pressure.

In an embodiment of the present invention the gasification method for the gasification of solid fuels containing ash with an oxidizing medium containing oxygen, in a gasification chamber designed as a flue stream reactor, at pressures between atmospheric pressure and 100 bar, in which the reaction chamber contour is confined by a cooling system, with the pressure in the cooling system being chosen to be higher than the pressure in the reaction chamber, may have the following features: The fuel, e.g. bituminous coal, bituminous coke and lignite coke, as well as biomass coke and/or petroleum coke and/or their mixtures, can be pulverized to a grain size of 500 gm, preferably 200 gm, and can be mixed to make a fuelin-water or fuel-in-oil suspension, a so-called slurry, by S:P59910 adding liquids such as water or oil. Stable solids concentrations of up to 70 wt.% can be achieved when using water as the carrier medium with added surfactants. These are brought to the desired gasification pressure of up to a maximum of 100 bar by means of suitable pumps, and may be then fed for the gasification reaction through suitable burners that can be attached at the head of the gasification reactor. The fuel concentration in the slurry and the amount of flowing slurry can be monitored, measured, and regulated by measurement devices, control devices, and monitors. An oxidizing medium containing free oxygen can be fed to the burner at the same time, and the fuel can then be converted into crude synthesis gas by partial oxidation. The gasification takes place at temperatures between 1,200 oC and 1,900 oC at pressures up to 100 bar. The reactor can be equipped with a cooling shield that consists of water-cooled pipes welded gas-tight.

The hot crude synthesis gas may leave the gasification chamber together with the liquid slag formed from the fuel ash, and arrive at a chamber perpendicularly under it, in which partial quenching can occur by injecting water or by feeding in a cold gas, whereby it is cooled to temperatures between 700 oC and 1,100 oC. At this temperature, the entrained liquid slag may have been cooled to the extent that S:P59910 it can no longer adhere to the metallic surfaces. The crude gas cooled to temperatures of 700 OC and 1,100 OC then arrives at a waste heat boiler together with the likewise cooled solid slag, to utilize the sensible heat for steam production. This preceding partial quenching or partial cooling may prevent or reduce the risk of slag caking on the waste heat cooling pipes. The water or recycled gas condensate needed for the partial quenching can be fed in through nozzles that are located directly on the jacket. The cooled slag can be collected in a water bath located at the bottom of the waste heat boiler. The crude gas, cooled to 200 OC 300 OC, can leave the waste heat boiler at the side and reach a crude gas scrubber, which can be a Venturi scrubber.

The entrained dust can then be removed down to a grain size of about 20 Mm. This degree of purity may still be inadequate for carrying out subsequent catalytic processes, for example crude gas conversion. It also has to be considered that salt mists can also be entrained in the crude gas, which may have detached from the powdered fuel during gasification and may be carried off with the crude gas. To remove both the fines gm and the salt mists, the scrubbed crude gas can be fed to a condensation step in which the crude gas can be chilled indirectly to about 5 OC-to 10 OC. Water can then be condensed from the crude gas saturated with water vapor, which may absorb the described fine dust and salt particles.

S:P59910 11 The condensed water containing the dust and salt particles can then be separated in a following separator. The crude gas purified in this way can then be fed directly, for example, to a crude gas converter or desulfurization system.

Instead of the scrubbing and condensation steps, a mechanical dust separator can be provided that operates at 200 °C to 300 for which centrifugal separators or filter systems can be used.

It would be advantageous if at least some embodiments of the present invention provided a possibility that takes into account the different ash contents of fuels and has high availability, with reliable operation.

Brief Description of the Drawings Notwithstanding any other forms which may fall within its scope, preferred forms of the invention will now be described, by way of example only, with reference to the accompanying drawings.

The Figures show: Figure 1 shows a block diagram of one embodiment the technology S:P59910 -12- Figure 2 shows an embodiment of a gasification reactor with partial quenching and perpendicularly arranged waste heat boiler Figure 3 shows an embodiment of a gasification reactor with partial quenching and adjacent waste heat boiler Detailed Description of Embodiments of the Invention Referring to the drawings 320 tons/hour of bituminous coal with a composition of C 71.5 wt.% H 4.2 wt.% O 9.1 wt.% N 0.7 wt.% S 1.5 wt.% Cl 0.03 wt.%, an ash content of 11.5 and a moisture content of 7.8 is to be gasified at a pressure of 40 bar. The calorific value of the coal is 25,600 kJ/kg. The gasification takes place at 1,450 OC. 245,000 m 3 (standard)/h of oxygen is needed for the gasification. The coal is first fed to a state-of-the-art grinder in which it is pulverized to a grain S:P59910 -13size range between 0 and 200 im, and is then mixed in a special system 1 according to Fig. 1 with water with added surfactants to make a stable coal dust in water suspension, the so-called slurry. The solids concentration in this slurry is 63 and the amount of slurry is 485 tons/hour. The slurry is brought to the desired gasification pressure of 100 bar by means of a pump suitable for pumping solid-liquid suspensions, and is fed to the burner of the gasification reactor 2 of Fig. 1 through the supply line 1.1, with the amount being monitored, measured, and regulated. To conserve oxygen, the slurry can be preheated up to 400 depending on the gasification pressure, prior to being fed into the gasification reactor 2.

Figs. 2 and 3 show the gasification reactor. The slurry flowing to the gasification reactor through the feed line 1.1 at 465 tons/hour is subjected to partial oxidation at 1450 °C along with the 245,000 m 3 (standard)/hour of oxygen flowing to the gasification chamber 2.3 through the line 2.1, with 565,000 m 3 (standard)/hour of crude gas being formed with the following composition:

H

2 18.5 vol.% CO 70.5 vol.% C0 2 6.1 vol.% S:P59910 -14-

N

2 2.3 vol.%

NH

3 0.003 vol.% HCN 0.002 vol.%

H

2 S 0.5 vol.% COS 0.07 vol.%.

The gasification chamber 2.3 is confined by a cooling shield 2.4 that consists of a water-cooled tube system welded gas-tight. The crude gas together with the liquid slag flows through the outlet opening 2.5 into the chamber 3.1 for partial quenching/partial cooling of the crude gas to temperatures of 700 OC 1,100 OC. At this temperature, along with the crude gas, the slag is also cooled to such an extent that it cannot be deposited in the pipes 4.1 of the waste heat boiler that follows according to Fig. 1. The steam generated in the waste heat boiler 4 is utilized in the process to preheat the oxidizing medium containing oxygen or as a gasification moderator to preheat the slurry. The slag is collected in a water bath 4.2 located at the bottom of the waste heat boiler and is discharged through 4.3. The crude gas leaves the waste heat boiler through 4.4 and arrives at the crude gas scrubber 5 according to Fig. 1. The waste heat boiler 4, however, can be located according to Fig. 3 directly beneath the gasification reactor 2 and the partial quencher 3, but also, as shown in Fig. 4, beside it. In this S:P59910 case, there is a slag discharge 4.3 beneath the partial quencher 3 and also one below the waste heat boiler 4.6. The crude gas leaving the waste heat boiler 4 through the outlet 4.4 then arrives at the crude gas scrubber 5 according to Fig.

1, which is an adjustable Venturi scrubber to which is fed about 100 m 3 /h of wash water. The wash water is freed of absorbed solids in the usual way and is fed again to the Venturi scrubber. The wash water can be preheated in order to wet the crude gas further at the same time as the washing. To remove fines 20 gm in size and salt mists not separated in the Venturi scrubber, the water-washed crude gas is subjected to partial condensation 6 according to Fig. 1, with the crude gas being chilled indirectly to about 5-100C. The finest dust and salt particles are taken up by the water vapor condensing during the chilling and thus removed from the crude gas. The crude gas cleansed of solids then has the following composition:

H

2 13.4 vol.% CO 51.4 vol.%

CO

2 4.5 vol.%

N

2 1.5 vol.%

NH

3 0.0022 vol.% HCN 0.0012 vol.%

H

2 S 0.36 vol.% S:P59910 -16- COS 0.05 vol.%

H

2 0 37.30 vol.% The purified, wet crude gas amounts to 775,000 m 3 (standard)/hour. It can be directly sent to a crude gas converter or to other treatment steps.

A reference herein to a prior art document is not an admission that the document forms part of the common general knowledge in the art in Australia.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.

S:P59910 -17- List of reference symbols used 1 i.i 2 2.1 2.2 2.3 2.4 2.5 3 3.1 3.2 3.3 4 4.1 4.2 4.3 4.4 4.5 4.6 6 Slurry preparation and infeed Slurry line Reactor Line for oxygen Burner Gasification chamber Cooling Shield Outlet opening Quenching cooler Quenching chamber Nozzles in 3 Transfer line from 3 to 4 Waste heat boiler Cooling pipes in the waste heat boiler 4 Water bath with slag in 4 Slag discharge from 4 Opening from 4 to the crude gas scrubber Water bath with slag 4 Slag discharge from 4 Crude gas scrubber Partial condenser S:P59910

Claims

1. Method for the gasification of fuels such as bituminous coals and cokes such as bituminous, lignite, biomass, and petroleum coke in the flue stream with an oxidizing medium containing free oxygen, by partial oxidation at pressures between atmospheric pressure and 100 bar and at temperatures between 1,200 and 1,900 degrees, consisting of the process steps of slurry preparation and infeed, gasification by partial oxidation in a reactor with cooled reactor chamber contour, partial quenching, crude gas scrubbing and partial condensation, wherein the crude gas scrubbing and partial condensation can be replaced by dry mechanical dust removal operating above the condensation point, wherein: a pulverized fuel with a grain size 200 gm, preferably 100 gm, is slurried with water with added surfactant in a special system, to obtain a fuel-in- water slurry with a solids concentration of 40-70 wt.%, and is brought to the gasification pressure of 100 bar by pumping, for which the slurry can be preheated to temperatures up to 400 OC, S:P5991 0 -19- the slurry fed to the reactor 2 through a supply pipe together with an oxidizing medium containing free oxygen is subjected to partial oxidation in the reaction chamber, whose contour is confined by a cooling shield, with the ash of the fuel being melted and transferred through the discharge device to the quenching chamber of the quenching cooler along with the hot gasification gas, the partial quenching takes place with cooling of the crude gas to temperatures between 700 and 1,100 OC, the partially quenched crude gas is cooled in a waste heat boiler to temperatures between 150 and 400 OC with generation of steam, the cooled crude gas is then subjected to a crude gas scrubber and partial condensation, or to dry mechanical dust separation by centrifugal force or filtration, to separate entrained dust, the cooled crude gas freed of dust is then sent to further treatment steps such as crude gas conversion or desulfurization. S:P59910

2. Method pursuant to Claim 1, characterized in that the crude gas scrubber is a single- or multiple-stage Venturi scrubber.

3. Method pursuant to Claims 1 and 2, characterized in that the Venturi scrubber is supplied with fresh water or recycled condensates that result from the cooling of the gas.

4. Method pursuant to Claims 1 to 3, characterized in that the waste heat boiler is operated at temperatures of 700 to 1,100 °C. Method pursuant to Claims 1 to 4, characterized in that the crude gas scrubbing takes place at temperatures of 150 to 300 °C.

6. Method pursuant to Claims 1 to 5, characterized in that the Venturi scrubbers are supplied with circulated water or recycled condensate.

7. Method pursuant to Claims 1 to 6, characterized in that the fuel is supplied to the reactor as a fuel-in- water slurry. S:P59910 -21-

8. Method pursuant to Claims 1 to 7, characterized in that the fuels are supplied to the gasification reactor through one or more burners.

9. Method pursuant to Claims 1 to 8, characterized in that the granulated slag is discharged through one or more outlets from the quenching chamber. Method pursuant to Claims 1 to 9, characterized in that the partially quenched crude gas leaves the quenching chamber through one or more gas outlets.

11. Method pursuant to Claims 1 to 10, characterized in that one or more varieties of coal are gasified at the same time.

12. Method pursuant to Claims 1 to 11, characterized in that the amount of slurry in the supply pipe is measured, monitored, and regulated.

13. Device for implementing a method pursuant to Claims 1 to 12, characterized by: a system for producing and feeding slurry, a gasification reactor with cooled reaction chamber S:P59910 22 contour, a quenching cooler for the partial quenching of the crude gas, a waste heat boiler, a crude gas scrubber, and a partial condenser, wherein the crude gas scrubber and partial condenser can be replaced or supplemented by a device for dry dust separation, positioned in succession, wherein a reactor for the gasification of supplied powdered fuel with an oxidizing medium containing free oxygen, consisting of the supply pipe for the slurried fuel and a line for the oxidizing medium, which is fed by burners into the reaction chamber, which consists of a cooling shield consisting of water-cooled pipes welded gas-tight and an outlet device into a quenching cooler, a quenching cooler with no internals, in which nozzles are arranged in one or more nozzle rings through which is sprayed the water necessary for partial quenching, with the nozzles being integrally incorporated in an inner jacket, a waste heat boiler following the quenching cooler, S:P59910 -23- are followed by equipment for purifying the gas.

14. Device pursuant to Claim 13, characterized in that the reaction chamber of the quenching cooler 3 is connected directly to the waste heat boiler, in which the sensible heat of the crude gas is utilized through tubes to produce steam, and there are discharge openings in the bottom of this for the crude gas and for slag withdrawal with a water bath. Device pursuant to Claims 13 and 14, characterized in that there are a crude gas scrubber and a partial condensation system following the crude gas scrubber for purification.

16. Device pursuant to Claim 15, characterized in that a single- or multiple-stage Venturi scrubber is used as the crude gas scrubber.

17. Device pursuant to Claims 13 and 14, characterized in that there is a mechanical dry dust separator for gas purification. S:P59910 -24-

18. Device pursuant to one of the claims 13 to 17, characterized in that other gas treatment stages such as a crude gas converter or a desulfurization system are connected in line after the water scrubber and partial condenser or the mechanical dry dust separator.

19. Device for implementing a method pursuant to Claims 1 to 12, characterized by a system for producing and feeding slurry, a gasification reactor with cooled reaction chamber contour, a quenching cooler for the partial cooling of the crude gas, a waste heat boiler, a crude gas scrubber, and a partial condenser, wherein the crude gas scrubber and the partial condenser can be replaced or supplemented by a device for dry dust separation, which are connected in series, a reactor for the gasification of supplied fuel dust with an oxidizing medium containing free oxygen, consisting of the supply pipe for the slurried fuel and a line for the oxidizing medium which are fed by burners into the reaction chamber, which consists of a cooling shield consisting of water-cooled pipes welded gas-tight and a discharge device into a quenching cooler, S:P59910 a quenching cooler from which the partially cooled crude gas flows through the transfer line to the waste heat boiler, a waste heat boiler that is equipped with boiler tubes and utilizes the sensible heat of the crude gas to produce steam, a crude gas scrubber, and a partial condensation system following the crude gas scrubber, which can be replaced by a mechanical filtration dust separator.

20. Device pursuant to Claim 19, characterized in that there are water baths and in both the quencher and the waste heat boiler, in which the cooled slag is collected.

21. Device pursuant to Claims 19 and 20, characterized in that there are devices for discharging slag on both the quencher and the waste heat boiler. S:P59910 -26-

22. A method for the gasification of fuels substantially as herein described with reference to the accompanying drawings and example. Dated this 20th day of March 2006 FUTURE ENERGY GMBH and SCHINGNITZ, DR MANFRED By Their Patent Attorneys GRIFFITH HACK S:P59910