AU620129B2

AU620129B2 - Process and device for the purification of raw gas from solids gasification reactors

Info

Publication number: AU620129B2
Application number: AU40030/89A
Authority: AU
Inventors: Rolf Buchenau; Rainer Dr Durrfeld; Hartmut Dr. Hederer; Harald Dr Hoffmann; Bernard Shleper; Dieter Victor
Original assignee: Hoechst AG
Current assignee: Ruhrkohl Ol und Gas GmbH; Hoechst AG
Priority date: 1988-08-16
Filing date: 1989-08-16
Publication date: 1992-02-13
Anticipated expiration: 2009-08-16
Also published as: DE58905238D1; ATE92949T1; AU4003089A; EP0358923B1; ES2045296T3; ZA896204B; DE3827702A1; DE3827702C2; EP0358923A1; JPH0291192A

Abstract

In a process and apparatus for purifying raw gas from solids gasification, containing granular and dusty solids particles, a solution is to be found, by means of which solids particles of any size are largely removed from the raw gas before entry to downstream cooling devices. This is achieved when the raw gas is passed in a first purification stage from the gasification zone in a straight line in the direction of a gas-holding space, whereby the granular solids particles are precipitated at the bottom of the gas-holding space and then, in a second purification stage, the partially purified raw gas is laterally deflected from the gas-holding space and undergoes a change to a velocity reduced by a factor of at least 3 and, after a further gas deflection, is passed substantially in the vertical direction through a solids filter, where the dusty solids particles are removed from the raw gas. <IMAGE>

Description

1 V w 0 Our Ref: 288951 AUSTRALIA 62 Q?0 2gomlo Patents Act

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COMPLETE SPECIFICATION

(ORIGINAL)

Application Number: Lodged: Complete Specification Lodged: Accepted: Published: *,Priority: *Related Art: Applicants: HWrEC'r\S1iEELLV c( Ru-A0oW,~a~xflM&c .Uhda GmbH -f Grigdr_ I hrmutr.

t-n-Federa-l-Repab1+ic-of -Germany.; *426--Bt-t-r-op---Fed-r-a4-Repu3li-e-eaf--Ger-many; ?\uHV\YAt&L Ou um &XAS &Mbvi OVi L18Azr-c ab.S 4&5 e)CAAW ~e~Uku~ AjL -jMrrjjjn1urn EetwrunaeLm ~-1----00-K-o-l-n-80-r-eda-.-Repu-i-e--of-Ge-r-ma-ny 0 Address for Service: ARTHUR S. CAVE CO.

Patent Trade Mark Attornerys Level 10, 10 Barrack Street SYDNEY NSW 2000 Complete specification for the invention entitled Process and device for the purification of raw gas from solids gasification reactors The following statement is a full description of this invention, including the best method of performing it known to me.-- 1ii i 3 4W/gs COMMONWEALTH OF AUSTRALIA j FEE: $150.00 j 3024W/gs

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056 Ov/MS 2 PROCESS AND DEVICE FOR THE PURIFICATION OF RAW GAS FROM SOLIDS GASIFICATION REACTORS The invention relates to a process and a device for the purification of raw gas from solids gasification units, said gas containing coarse and fine particles. Gasification of solids is mainly understood to mean gasification of hard coal or lignite. The coal may be fed to the reactor as coal dust or coal slurry, at the same time admixing an oxidizing so** agent such as air or oxygen-rich air. The hot raw gas may o be passed through the coal bed or be withdrawn o counter-currently from the reactor. The invention is not S*o related to the purification of raw gas flowing through the o* coal bed but pertains to the gas withdrawn freely from the o reactor.

It is recommended that, in the case of freely withdrawn gas, the slurry portion of the feedstock be solidified by known means since solidified particles can be easily removed °.00o from the gas stream.

.v .o The raw gas generated in the above mentioned gasification unit contains a certain portion of solids and Smust therefore be subjected to purification in order to a0j remove the residual solids prior to any further treatment of Sthe raw gas, for example cooling. This requirement could so 0 far not be fulfilled at all or only indadequately.

j o e DE-PS 32 23 702 describes a process for generating t synthesis gas, coal dust and oxidizing agent being fed to the reactor. The coarse particles collect in and are withdrawn from the lower part of the reactor, the synthesis gas and flue ash dust) being ducted to a heat exchanger which simultaneously serves as flue ash separator. The different gas stream velocities and the long gas pipe route to the cyclone downstream of the heat exchanger will inevitably cause dust deposits, mainly in the heat exchanger. Hence, the heat exchanger efficiency is substantially reduced or the exchanger has to be cleaned at frequent intervals.

EP-PS 0 077 851 describes a gas cooler system for cooling the products from a coal gasification reactor. This pv LC A"i i

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SMEETON

3028F/MS i, 056'Ov/MS 2a new configuration brings about the precipitation of the fine-grained ash on the tubes of the convection-type gas cooler which must have at least one rising pass for the gas to be cooled. However, special cleaning equipment such as soot blowers have to be installed in order to clean the exchanger surfaces of the cooler.

In one broad form the present invention is a two-stage process for the purification of raw gas generated in a solids gasification unit and containing coarses and fine particles, *900 characterised in that the raw gas flows from the gasification section directly into a gas impact chamber of v the first stage, the coarse fraction of the particles S falling into an ash collecting chamber at the bottom of the r Sft gas impact chamber, and further characterized in that the raw gas stream leaving the impact chamber is diverted radially, the flow velocity being reduced by at least a factor three, and deflected upwards in order to enter the second stage in which the gas passes a solids bed filter required to separate the fine portion of the dust particles.

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S-3 i -3- The invention provides for a two-stage process for the purification of raw gas gener- ',L ated in a solids gasification unit and containing coarse and fine particles, said process being characterized in that the raw gas flows from the gasification section directly into gas impact chamber of the first stage, the coarse fraction of the particles falling int o the ash collecting chamber at the bottom of chamber and characterized in that the raw gas stream leaving impact chamber is reversed radially, thereby reducing the flow velocity by factor 3, and deflected upwards in order to enter the second stage in which the gas passes a solids bed filter required to separate the fines from the dust particles.

According to an embodiment of the invention, this process is implemented by means C' of a device characterized in that the lower section of the gasification reactor has a .C gas outlet adjacent to the peripheral gas inlet chamber arranged above the solids bed filter. The major advantage of the invention is that this process permits the removal of coarse and fine particles from the raw gas in two successive stages without inter- 1 i mediate gas pipe sections or additional vessels which are susceptible to trouble.

Moreover, the major velocity reduction due to reversion and deflection of the gas stream permits a uniform gas flow through the filter. According to the invention the I surface area for the raw gas from which the coarse fraction has already been re- moved but which still contains dust, is at least 3 x larger than the cross-sectional area of the gas outlet pipe of the gasification reactor, thus improving the gas flow further.

0e 0 o0o0 The example indicated below serves to describe the invention: Gas volume to be purified: 7 040 ma/h Composition: CO -42% H CO 11%

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2 0- other gas fractions 2% dust content 46.7 g/m 3 at NTP coarse fraction thereof approx. 85 fine fraction thereof approx. 15 Gas temperature: 500 700 °C Filter bed material: sand grain size 0.5 3 mm bed temperature 500 to 700 °C ZVAP07001280689 1 l i

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-4- Filter spectrum 90 to 99 The drawings indicated below serve to illustrate the invention: Fig. 1: Fig. 2: Typical process flow sheet Device with solids bed filter Figure 1 shows a section of gasification reactor 1 which may be of any type, the raw gas leaving the reactor via conical outlet 2 at the reactor bottom. Gas impact chamber 3 is located below said outlet and serves to reverse the gas stream radially which then flows upwards and enters filter inlet chamber 4. The coarse fraction of solids contained in the gas is not entrained because of the reversion, but falls into r ash collecting chamber 5 at the bottom of the gas impact chamber and is withdrawn periodically via outlet 6. The gas containing dust particles of 0 to 20mm0 .Lm leaves chamber 4, passes through fixed-bed filter 7 and collects in outlet chamber 8. It is then ducted via outlet 9 to a downstream heat recovery unit. The temperature of the purified gas is still above 5000C.

C r C C t cC c C C Ci C According to Fig. 2, heat exchanger 10 is incorporated into the lower section of gasification reactor 1 in order to cool the gas to 500 7000C. The raw gas passes through the heat exchanger, leaving no significant deposits of dust particles. Ash collecting chamber 5 may also be filled with water. Fixed-bed filter 7 is preferably designed as a ring consisting of a multitude of sectors filled individually with filter material via inlets 11. When a dust layer has formed on the filter surface, the top layer of the filter is evacuated by means of return gas injected via nozzles 12 and falls into ash collecting chamber 5. The purified gas from filter 7 is withdrawn via -eader 13. The filters are filled with fresh sand from sand bin 14 via inlet 11 as shown in Figure 2.

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Claims

1. A two-stage process for the purification of raw gas generated in a solids gasification unit and containing coarse and fine particles, characterized in that the raw gas flows from the gasification section directly into a gas impact chamber of the first stage, the coarse fraction of the particles falling into an ash collecting chamber at the bottom of the co gas impact chamber, I 0e00 and further characterized in that the raw gas stream a a leaving the impact chamber is diverted radially, the flow velocity being reduced by at least a factor of three, and *oeoo deflected upwards in order to enter the second stage in o o which the gas passes a solids bed filter required to separate the fine portion of the dust particles.

2. A process according to claim 1, characterized in that the solids bed filter is filled with sand. 0 0 0009 o0 o

3. A process according to claim 1 or 2, characterized in o~oo that the process in the second purification stage take place at 500°C. 000000 o

4. A device for the purification of raw gas generated in a '00 9 solids gasification unit and containing coarse and fine particles, said device comprising a gasification reactor with a vertical cooling section and with a raw gas outlet and collecting chamber in the lower part, characterized in that a peripheral filter chamber is adjacent to the raw gas outlet and above a solids bed filter.

A process according to claim 1 and substantially as j herein described with reference to any one of the s accompanying drawings. i -O O56,Ov/MS 6

6. A device according to claim 4 and substantially as herein described with reference to any one of the accompanying drawings.

7. A two-stage process for purification of raw gas substantially as herein described and with reference to the example. o r. *bP 0 *r 0 DATED this 26th day of November, 1991. HOESCH AG RUHRKOHLE GMBH By Their Patent Attorneys DAVIES COLLISON CAVE S coo, o 9 00 S S oa *i O C o 0 S i i_ B