AU2013214549A1

AU2013214549A1 - Apparatus and process for gasification of solid hydrocarbonaceous fuels in dust form in an entrained flow

Info

Publication number: AU2013214549A1
Application number: AU2013214549A
Authority: AU
Inventors: Guido LANGENKAMP; Domenico Pavone; Steffen Schirrmeister; Reinald Schulze Eckel; Dobrin Toporov
Original assignee: ThyssenKrupp Industrial Solutions AG
Current assignee: ThyssenKrupp Industrial Solutions AG
Priority date: 2012-02-03
Filing date: 2013-01-23
Publication date: 2014-08-14
Also published as: CU20140098A7; UA112998C2; IN2014DN06997A; CN104220565B; BR112014019007A8; TW201343896A; EP2809751B1; CU24153B1; PL2809751T3; BR112014019007A2; RU2014134102A; WO2013113478A1; CN104220565A; EP2809751A1; KR20140123557A; CL2014002011A1; DE102012001986A1

Abstract

A gasification reactor for gasification of solid hydrocarbonaceous fuels in dust form in an entrained flow, comprising a first reaction space disposed at the top of the reactor, in the upper region of which is disposed a feed apparatus for feedstocks, the side walls of which are equipped with pipes having internal cooling in the form of a membrane wall or pipe coils, on which liquid slag can run off freely without the surface of this slag solidifying in the process, and on the underside of which is provided an orifice for slag running off and synthesis gas exiting, with connection at the bottom of the orifice to a second space in which the crude gas is kept dry and cooled by radiative cooling, and an apparatus for production of a water mist is provided, the second space is connected at the bottom to a third space in which feed devices for water are provided, the third space is connected at the bottom to an accommodating device for a water bath which also has a removal apparatus for a water-slag mixture, and a removal apparatus for crude gas from the reactor provided at the bottom or side of the third space has an axially symmetric extension space which forms the transition from the first to the second space, and the lower edge of which is arranged at the same height or above the height at which the free-falling water mist emerges.

Description

1 Contrivance and process for the entrained-flow gasification of powdery solid carbonaceous fuels [0001] The invention relates to a process and a contrivance for the entrained-flow gasifica tion of powdery solid carbonaceous fuels. [0002] In the commercial-scale plants for entrained-flow gasification that have been con structed hitherto, systems including waste heat utilisation were implemented in the case of both the Shell Coal Gasification Process (SCGP) and the Pressurised Entrained Flow Process (PRENFLO), as these involve advantages in efficiency in the Integrated Gasification and Com bined Cycle (IGCC) without separation of carbon dioxide. Here, the sensible heat of the crude gas generated in the gasifier is converted into steam via heat exchanging surfaces, the steam then being transformed by a steam turbine into electric power. [0003] In power plant processes including the separation of carbon dioxide, Carbon Cap ture and Storage, IGCC--CCS, and the employment of a coal gasification for the production of various chemical products as, for example Coal to Liquid (CTL), Fischer--Tropsch (FT), metha nol, ammonia, the carbon monoxide is converted partially or completely in the process chain in order to generate the respectively required ratio of carbon monoxide to hydrogen in the syngas. For this purpose, the crude gas is enriched with steam at a ratio of 1 to 1.2 up to 1 to 1.4. In the case of systems including waste heat utilisation, the steam which is produced with a high de mand for equipment is subsequently admixed again to the crude gas after minor energy utilisa tion in the steam turbine. [0004] The increase of the steam content in the crude gas can also be achieved with a considerably reduced demand for equipment by direct quenching of the crude gas stream with water. In this process variant, the 1200 to 1500 0 C hot crude gas is quenched with water di rectly at the exit of the gasification chamber and, at the same time, cooled. All heat exchanging surfaces including the related accessories as steam drum and recycle pumps, for example, are not required in contrast to the process variant including waste heat utilisation by steam genera tion. [0005] The direct feed of water to the process gas stream, however, also entails techno logical problems. Quenching the crude gas stream with water may, in fact, cause material fa tigue problems. This is because the material is subjected to enormous stress whenever individ ual water droplets fall onto metal, cooling and quenching it immediately. It is therefore abso lutely necessary to avoid that droplets be entrained onto hot surfaces and components. [0006] The systems including waste heat utilisation provide for dry separation of the fine ash portion entrained with the crude gas stream on the cold side by means of a ceramic high temperature filter at approx. 300 0 C. If direct quenching in the hot section of the gasification is carried out, there is tendentiously always the risk of deposits and incrustations of slag and dust 2 portions of the hot gas stream when liquid slag components and ash get in touch with cooled surfaces and get spontaneously cold and solid. Such incrustations involve a further risk as they will grow in an uncontrolled manner, change the flow conditions uncontrollably and may sepa rate as undefined lumps in an incalculable manner. They will then clog up the slag discharge devices or disturb and destroy other components of the contrivance. [0007] Prior art also discloses a technology that widely takes into account the occurrence of problems of such kind. WO 2009/036985 Al thus describes a gasification reactor and a process for entrained-flow gasification, in which the reactor is subdivided into three chambers through which the syngas produced flows one by one. In the first chamber, liquid slag is obtained which drops off a slag drop-off edge at the gas exit of the first chamber in concurrent with the down ward syngas flow and drops into a water bath at the end of the second chamber. In the second chamber, which is separated from the first chamber by a free-falling water curtain, the syngas is cooled, while the water curtain heats up but scarcely vaporises. In the third chamber, the syn gas is quenched by injected water, thus increasing the water content of the syngas. When the syngas reaches the third chamber, it has cooled down to such an extent that it is free of parti cles tending to incrustation. [0008] WO 2009/036985 Al teaches that the water curtain may be generated by a ramp shaped as a funnel. WO 2011/107228 A2 describes another contrivance which serves to im plement a water curtain in such a gasification reactor consisting of three chambers; in the latter case, however, improved possibilities are provided to adjust the amount of water and the fall velocity and form of fall of the water curtain. In both cases, however, the hot gas stream itself and turbulent flow conditions may cause that parts of the water curtain swirl upwards and may enter the first chamber. This would lead to problems at the slag drop-off edge and on the equipment items in the first chamber. [0009] In order to reduce eddies, WO 2009/118082 A2 teaches to use eddy-reducing or eliminating wall surfaces running over only part of the cross section of the connection channel. Although measures of this kind are suited to reduce the amount of fly ash and to break gas ed dies the rotation axis of which runs in parallel to the reactor axis, they do not slow down the gas flow, nor do they prevent gas eddies the rotation axis of which runs crosswise to the reactor axis. In addition, they do not prevent the water curtain from lifting nor droplets from being en trained. [0010] The aim of the invention is therefore to provide an improved constructional solution which counteracts such problems in an effective way. The solution is firstly intended to achieve that the flowing-off ash forms streaks and that further slag guiding channels are provided to en sure optimum slag discharge. Secondly, a separation of the free jet from the rear space is in tended to avoid water swirls in the hot section in order to prevent intensified material fatigue by temperature cycling stress and incrustations.

3 [0011] The invention achieves this aim by means of an axially symmetrical extension sec tion at the exit of the chamber where the gasification reaction takes place. The axially symmetri cal extension section serves as a guide for the exiting main gas jet stream and prevents that the gas jet stream has an injector effect. The contrivance especially relates to a gasification reactor for the entrained-flow gasification of powdery solid carbonaceous fuels, * with a first reaction chamber arranged at the top of the reactor, the upper section of which is equipped with a feed device for feedstock, the side walls of which are provided with tubes with internal cooling as membrane wall or tube coils, which allow free down-run of liquid slag without the surface of the slag solidifying, and the bottom of which is provided with an open ing for exiting slag and exiting syngas, * with a second chamber being connected to the the bottom of the opening, where the crude gas is kept dry and cooled by radiant cooling, and a device being provided for generating a water curtain, * the bottom of the second chamber being connected to a third chamber, which is equipped with feed devices for water, * a holding device for a water bath being connected to the bottom of the third chamber, the device also being provided with a discharge device for a water/slag mixture, * and a discharge device for crude gas from the reactor being provided at the bottom or side of the third chamber, characterised by an axially symmetrical extension section, * which forms the transition from the first to the second chamber, * and the bottom edge of which is arranged at the same level or above the level of the outlet of the free-falling water curtain. [0012] An embodiment of the invention provides for an edge-to-edge arrangement of the top edge of the axially symmetrical extension section and the bottom of the reaction chamber. [0013] Another embodiment of the invention provides for the axially symmetrical extension section being designed as a diffuser, with the bottom edge being provided as a drop-off edge for slag. The diffuser is designed to feature an angular aperture of 1 to 15 degrees, preferably 5 to 8 degrees. [0014] A further embodiment of the invention provides for an extension of the cooling sys tem of the reaction chamber side walls, which are provided with internally cooled tubes with internal cooling as membrane wall or tube coils, to the external walls of the axially symmetrical extension section. These may be studded and stamped on the side towards the gas stream. A 4 further design variant comprises internally cooled tubes which are coated against high temperature corrosion on the gas side. [0015] The diffuser according to the invention must not be confused with a shielding device as shown in Fig. 3 of WO 2009/036985 Al; the shielding devices shown there serve to protect the pressure vessel from excessive radiation heat and are also used in the variant with tubular partition. The tubular partition is not meant to shield the pressure vessel but to separate and guide the flow of the exiting gas jet stream and is therefore of correspondingly different design. [0016] The invention also relates to the process for the entrained-flow gasification of pow dery solid carbonaceous fuels using an axially symmetrical extension section as described above, the invention being characterised in that the gas stream, which features a high velocity at the exit of the reaction chamber, is slowed down. In addition, the exiting gas stream is shielded off from the rear space and can thus no longer develop its injector effect. This slow down of the stream, which is achieved by homogenising the flow distribution in combination with enlarging the cross section, results in the reduction of the differential pressure between the top and the bottom of the water lamella. In this way, the tendency of the gas jet stream to lift and partly swirl the water curtain is significantly reduced. Another effect is that no gas eddies can form above the water curtain, by which droplets could be entrained to hot components of the reaction chamber. [0017] The invention is illustrated below in more detail by means four drawings. Of these Fig. 1 shows a reactor according to WO 2009/036985 Al with an additional gas diffuser. Fig. 2 shows the transition section from the reaction chamber to the second chamber including the gas diffuser and a water ramp for generating a water curtain. Fig. 3 shows the transition section from the reaction chamber to the second chamber including the gas diffuser and an alternative device for generating a water curtain. Fig. 4 shows the transition section from the reaction chamber to the second chamber including an alternative axially symmetrical extension section. [0018] At the upper end, Fig. 1 shows the reaction chamber of gasifier 1 with burners 2. The approx. 1500 OC hot crude gas, which contains liquid slag droplets and ash particles, leaves the reaction chamber of gasifier 1 through the exit from reaction chamber 3, with the crude gas normally featuring a swirl to the effect that major part of the liquid slag deposits on the cooled walls of the reaction chamber and runs down as liquid in the wall area of the exit. The hot crude gas is slowed down in gas diffuser 4 and homogenised across the cross section. [0019] It impinges on water curtain 5 which acts as a cooling surface and quickly cools down the hot crude gas. This cooling procedure makes the liquid slag droplets solidify and 5 keeps them from incrusting on the walls. The water curtain is generated on water ramp 6. The size of the amount of water for the water curtain is selected such that the water curtain does not get so hot to start boiling and evaporating. In this way, the crude gas still stays almost com pletely dry in this cooling zone which forms the second chamber 8. Gas diffuser 4 prevents the gas stream from lifting water curtain 5 and droplets from reaching shield 7 or drop-off edge 10. Drop-off edge 10 of gas diffuser 4 is arranged just above water curtain outlet 9. [0020] In the following third chamber 11 the crude gas which is still hot is quenched with water from nozzles. Third chamber 11 is subdivided by partition wall 12 and extended in annular space 15; the cooled-down slag particles from the quenched crude gas and the solidified slag droplets from drop-off edge 10 drop into water bath 13 and are discharged at slag discharge 14. The saturated syngas leaves the gasification reactor through syngas outlet 16. [0021] Fig. 2 shows the transition section, which is equipped with the gas diffuser, in a sec tional view. Fig. 3 shows the same sectional view, in which the water ramp has been replaced by a nozzle torus according to WO 2011/107228 A2. [0022] Fig. 4 shows the same sectional view, in which an alternative axially symmetrical extension section is used. This embodiment provides for an enclosure 18, the bottom edge of which is at the same level as the opening of free jet stream 19 of the syngas.

6 List of reference numbers and designations: 1 Reaction chamber of gasifier 2 Burner 3 Exit from the reaction chamber 4 Axially symmetrical extension section 5 Water curtain 6 Water ramp 7 Shield 8 Second chamber 9 Water curtain outlet 10 Drop-off edge 11 Third chamber 12 Partition wall 13 Water bath 14 Slag discharge 15 Annular space 16 Syngas outlet 17 Nozzle torus 18 Enclosure 19 Free jet stream

Claims

1. Gasification reactor for the entrained-flow gasification of powdery solid carbonaceous fuels, * with a first reaction chamber arranged at the top of the reactor, the upper section of which is equipped with a feed device for feedstock, the side walls of which are pro vided with tubes with internal cooling as membrane wall or tube coils, which allow free down-run of liquid slag without the surface of the slag solidifying, and the bottom of which is provided with an opening for exiting slag and exiting syngas, * with a second chamber being connected to the bottom of the opening, where the crude gas is kept dry and cooled by radiant cooling, and a device being provided for generating a water curtain, * the bottom of the second chamber being connected to the bottom of the third cham ber, which is equipped with feed devices for water, * a holding device for a water bath being connected to the third chamber, the device also being provided with a discharge device for a water/slag mixture, * and a discharge device for crude gas from the reactor being provided at the bottom or side of the third chamber, characterised by an axially symmetrical extension section, * which forms the transition from the first to the second chamber, * and the bottom edge of which is arranged at the same level or above the level of the outlet of the free-falling water curtain.

2. Contrivance according to claim 1, characterised in that the upper edge of which is ar ranged edge-to-edge with the bottom of the reaction chamber.

3. Contrivance according to claim 2, characterised in that the axially symmetrical exten sion section is designed as a diffuser, with the bottom edge being provided as a drop-off edge for slag.

4. Contrivance according to claim 3, characterised in that the diffuser features an angular aperture of 1 to 15 degrees. 2

5. Contrivance according to claim 4, characterised in that the diffuser features an angular aperture of 5 to 8 degrees.

6. Contrivance according to one of claims 1 to 5, characterised in that the cooling system of the side walls of the reaction chamber, which are provided with internally cooled tubes with internal cooling as membrane wall or tube coils, is extended to the external walls of the axially symmetrical extension section.

7. Process for the entrained-flow gasification of powdery solid carbonaceous fuels using an axially asymmetrical extension section according to one of claims 1 to 6, characterised in that the gas stream, which features a high velocity at the exit of the reaction chamber, is slowed down before entering the second chamber, where the crude gas is kept dry and cooled by radiant cooling, and where a water curtain is generated.