WO2013060457A1

WO2013060457A1 - Method for the automatic removal of an excess of carbon in a gasification reactor

Info

Publication number: WO2013060457A1
Application number: PCT/EP2012/004458
Authority: WO
Inventors: Martin ZUCKERMAIER; Thomas Tschaftary
Original assignee: Ligento green power GmbH
Priority date: 2011-10-28
Filing date: 2012-10-25
Publication date: 2013-05-02
Also published as: DE102011117141A1; EP2771438A1

Abstract

A method for the automatic removal of an excess of carbon in a gasification reactor (1) having a reaction chamber (4) for the autothermal and/or allothermal gasification of carbon-containing fuel to form useful gases should make it possible to realize particularly high efficiency and particularly high operational reliability while placing lower demands on the fuel used during operation of a gasification reactor. For this purpose, in the event of a predefined value characteristic of the amount of excess carbon in the reaction chamber (4) being exceeded, the composition, amount, pressure, speed, temperature and/or specific outlet pulse of a gasification agent metered into the reaction chamber (4) are changed such that a combustion of the excess of carbon is intensified.

Description

description

Method for the automatic removal of excess carbon in a gasification reactor

The invention relates to a method for the automatic removal of a carbon excess in a gasification reactor with a reaction chamber for the autothermal and / or allothermal gasification of carbonaceous fuel to Nutzgasen.

definitions

In the present invention, a reactor is generally understood to mean a part of a plant in which chemical reactions of one or more starting materials to one or more products are carried out. Therefore, in this invention, under a gasification reactor, a container is understood to be a part of an installation in which carbonaceous fuel material is converted into useful gases, ie gasified.

In the present invention, a useful gas is understood as meaning a substance or a substance mixture which is suitable both itself as fuel for internal combustion engines and also as raw material for further chemical production processes.

In the present invention, a carbonaceous fuel material is understood to mean such a material whose carbon contained in the form of an exothermic reaction oxidizes to carbon dioxide (CO ₂ ) in air, that is to say it can be burned. In this sense, the carbonaceous fuel includes, in particular, biomass, fossil fuels, and synthetic-organic materials, especially carbon-containing plastics. In the present invention, biomass is generally understood to mean any carbonaceous substance derived directly or indirectly from physiological processes of living organisms,

CONFIRMATION COPY especially from plant photosynthesis, is not deprived of the natural carbon cycle and can be exothermally converted by organisms to CO2. Examples of biomass are fermentation residues, wood, leaves, hay, straw, paper, cardboard, compost, faeces and sewage sludge.

In the present invention, fossil fuels are understood to mean those forms of biomass which are located in a geological depression and are thus removed from the natural carbon cycle. Examples of fossil fuels are asphalt, tar, bitumen, peat, lignite, hard coal and graphite.

A carbonaceous fuel material may also be understood to mean a mixture of different carbonaceous fuel materials, for example biomass, synthetic-organic materials and especially plastics. Another example of a carbonaceous fuel is therefore household waste as a mixture of such fuels. Thus, the shape of the carbonaceous fuel is independent of its shape, another example is wood in the form of logs, wood chips of varying size, sawdust or in the form of pellets.

Technical background

The pyrolysis as a purely thermal decomposition of biomass, hard coal and lignite runs predominantly endothermic depending on the oxygen content and the binding of the oxygen. Within the fuel, the pyrolysis may also be exothermic. In particular, in the pyrolysis of hard coal or brown coal arise in addition to carbon monoxide (CO), hydrogen (H ₂ ) and methane (CH ₄ ), for example, still volatile hydrocarbons. Plastics, which consist for example only of carbon and hydrogen, pyrolyzed under exclusion of air exclusively to lower hydrocarbons. Carbon monoxide (CO), hydrogen (H ₂ ) and methane (CH ₄ ) and volatile hydrocarbons are flammable, are ideally suited as fuels for internal combustion engines, are important starting materials for many chemical manufacturing processes and are thus valuable. full useful gases. Methane (CH ₄ ) and pure carbon, for example in the form of mineral graphite or synthetic coke, are not or no longer pyrolysable.

However, carbon-containing fuels can be converted to useful gases with gasifiers, for example carbon with a deficiency of O ₂ to CO, then carbon with water (H ₂ O) to CO and H ₂ , then CH ₄ with O ₂ to CO. However, the gasification reactions of carbonaceous fuel with H ₂ O are endothermic. As a natural gasification agent is used in particular air, which may also be enriched with H ₂ O, for example as an aerosol or vapor. In the present invention, therefore, a gasification agent is understood to mean a pure substance or substance mixture whose addition to the carbonaceous fuel material increases the conversion into useful gases.

The gasification of carbonaceous fuel to Nutzgas is predominantly economical only if the fuel is not only readily available or cheap, but the gasification in their energy balance depends solely on the energy content of the fuel. This relates in particular to the use of the useful gas as actual fuel for internal combustion engines, for example for the operation of a gas engine or a gas turbine. The gasification of carbonaceous fuel to Nutzgas then requires a total exothermic running overall process, the energetic itself as long as enough fuel is available. In addition, the heat released can also be used, for example, for heating residential buildings, as is the case with combined heat and power in combined heat and power plants (CHP). In a CHP, an internal combustion engine is in turn coupled to a generator, which then finally converts mechanical energy into electrical energy.

The combustion of carbonaceous fuel with O ₂ to CO, however, is so weakly exothermic that the energy released is not sufficient to sustain simultaneously ongoing pyrolysis and / or gasification reactions with H ₂ O permanently. The energy required for the entire gasification process must therefore be replaced by the highly exothermic combustion reaction of carbon monoxide. fuel with O ₂ to C0 _{2 are} applied. The highest possible efficiency in terms of Nutzgas- and heat yield of such an autothermal gasification is achieved at an optimum, in which the extent of combustion to CO ₂ just sufficient to provide the necessary energy contribution for pyrolysis and gasification reactions. This optimum in terms of incomplete combustion depends on the composition and nature of the fuel, the supply or optimal metering of the gasification agent, the nature and isolation of the gasification reactor and thus summarized by the entire reaction. Here, the change in the fuel during the entire gasification process is also taken into account or not negligible.

In the classic fixed bed gasification reactor, wood is a carbonaceous fuel, like a normal grate on a grid. As a countercurrent process, air is sucked through the grate and the burning wood as a gasifying agent. The upper layers of wood burn only partially and pyrolyze at the same time to Nutzgas, which is sucked off at the upper end of the furnace. Air and natural gas move countercurrently in the opposite direction to the slowly sinking wood. The resulting useful gas has a relatively low temperature of about 100 ° C and contains due to the ongoing drying and pyrolysis of the wood correspondingly much water vapor and organic constituents, which condense on further cooling to an acidic wood tar.

In the co-current method for wood gasification, air is fed as a gasifying agent directly above the grid directly into the hot gasification reaction zone of the fixed-bed gasification reactor and sucked under the grate. The internal reactor gas and the useful gas and air move in the same direction in the area of the grid, ie in direct current. The temperature of the reactor internal gas or useful gas is much higher here than in the countercurrent process. The useful gas as end product from the reactor internal gas contains significantly less wood tar, wherein the wood tar produced in the DC process has a basic pH.

The wood tar produced as a surplus of carbon in countercurrent and DC wood gasification processes is not suitable for internal combustion engines, but damages them due to its adhesive properties. Also in the gasification of other carbonaceous fuels, similar high-viscosity residues occur, which are generally referred to as condensate in the present invention. The resulting condensate not only reduces the efficiency with respect to material utilization balance of the gasification reactor, but must be removed from the useful gas by a gas scrubber. This additionally reduces the energy balance of the entire system and additionally requires washing liquid, for example water. Since the condensate is not only corrosive due to its pH, but also toxic and difficult to biodegrade, this results in a disposal problem. In US 2010/0107494 A1, a fixed-bed gasifier for biomass with a successive fuel supply is proposed, which although promises a higher efficiency in terms of fuel sales balance, but does not eliminate the formation of condensate or the resulting condensate can not continue to use in the gasification process.

One approach to the gasification of carbonaceous solid fuels is to use fluidized bed gasification reactors in which the fuel is converted into useful gases in an incomplete fluidized bed furnace. In this case, no condensate is generated, since this is also converted to Nutzgasen. However, gasification in fluidized bed gasification reactors is limited to solid fuels having a particle size of less than 40 mm with a water content of at least 25% by weight, the particles having to be suspended by a fluid fluid that constantly swirls, for example air. To maintain the fluidized bed, therefore, an external fluid supply with a high flow rate is necessary, which corresponds to an externally supplied work. Furthermore, fluidized-bed gasification reactors can not be operated autothermally, but only allothermally, ie with the supply of external heat energy. The total intake of these two types of energy is deduct the degree of the plant. This gasification technology is only economical for power plants in the power range of 1, 5 to 3 MW, whereby the overall efficiency is only about 30%.

A special form of the fluidized-bed gasification reactor is the Winkler generator, in which the fluidized bed can be maintained even better in the entire reactor space by means of ring loops arranged in series around the reactor body. Advantages of the Winkler generator are a homogeneous temperature distribution and better mixing of the particles compared to other fluidized bed gasification reactors. However, the Winkler reactor is only suitable for the gasification of coal, especially lignite, limited to the smallest possible particle size.

A significant improvement of the fluidized bed gasification reactor is provided by the entrained flow gasification reactor in which the carbonaceous

Fuel is introduced as dust, slurry or paste as a burner in the gasification room. Here, the gasification processes take place in a cloud of dust. This form of supply requires a corresponding pretreatment of the fuel, especially in biomass as a fuel to be introduced via a pneumatic system in the carburetor and gasified there in a very short time. Even such systems can be operated only with supply of work and heat energy. Here, the supply of heat energy by a continuous ignition with a Zündfackel.

The Koppers-Trotzek reactor as a special form of entrained flow gasification reactor is particularly suitable for the gasification of finely ground coal to useful gas. The coal dust is fed in at high speed, so that only a single ignition is needed and the gasification process can otherwise be performed autothermally. However, operation of the Koppers-Trotzek reactor still requires the supply of work to maintain the flow of air. Both in the various embodiments of the fluidized bed gasification reactor and those of the entrained flow gasification reactor, the gasification processes can not be maintained solely by the supply of fuel. In all versions of these reactor types, the overall efficiency is limited to a maximum of 30 to 40% by the necessary supply of work to maintain the vortex or flight flow. According to the prior art fixed-bed gasification reactors with cocurrent or countercurrent principle, fluidized bed and entrained flow gasification reactors are limited to the specific nature of the carbonaceous fuel material, in principle, a pretreatment of the respective carbonaceous fuel material is required. Necessary pretreatments of the fuel material also considerably limit the cost-effectiveness of gasification plants, in particular CHP plants. Although in fixed-bed gasification reactors compared to the fluidized bed and entrained-flow gasification reactors the supply of external work is limited only to that of the carbonaceous fuel and the gasifier, maintaining optimal conditions for the pyrolysis as well as gasification reactions is generally more difficult. In fixed bed gasification reactors with a DC or countercurrent principle, the definition of a given fuel quality and piece size, for example, to so-called G50 wood chips, particularly disadvantageous. Deviations from this, especially in terms of piece quality, water content and dust content, cause varying pressure and temperature conditions. Such deviations then require, for example, an excessive supply of air as a gasification agent. This leads to a strong dilution of the Nutzgas by atmospheric nitrogen and water vapor and an increased formation of entrained condensate. Quality and yield of the useful gas are then reduced so much that a costly gas scrubbing must be carried out prior to its utilization. Increased formation of condensate not only significantly lowers the overall efficiency of the plant, but also leads to blockages in the reactor, which can lead to complete failure of the entire plant. In addition, the purification of fixed bed gasification reactors of condensate is very expensive. Task and solution

The invention is therefore based on the object to provide a method which allows a particularly high efficiency and very high operational stability with lower demands on the fuel used in the operation of a gasification reactor. This object is achieved by the feature combination of claim 1 in an inventive manner. The dependent claims include in part advantageous and in part self-inventive developments of the invention.

The invention is based on the idea that a particularly high degree of efficiency as well as a particularly high operational stability would be achievable if an automatic removal of carbon excesses, which could lead to clogging of the reactor, would be possible. The invention is based on a gasification reactor with a reaction chamber for the gasification of carbonaceous fuel by the addition of gasification agents to Nutzgasen based. In the reaction chamber is the carbonaceous fuel. In the case of solid fuel materials, a continuous supply can take place via a reservoir connected to the reaction chamber. The conversion to the Nutzgasen as the sum of all individual pyrolysis and gasification reactions therefore takes place predominantly in the reaction chamber. The gasification reactor can also be designed completely as a reaction chamber.

An essential feature of the invention according to claim in the exceeding of a predetermined, characteristic of the amount of excess carbon in the reaction chamber composition, amount, pressure, velocity, temperature and / or specific exit pulse of the reaction chamber added gasification agent such that combustion of Carbon excess is increased. In other words, the gasification reactor is not operated in a certain operating state like all known reactors, but upon detection of excessive carbon excess in the reaction chamber, the reaction conditions in the chamber are changed such that this carbon excess degraded, ie burned. The reactor thus switches from a gasification to a carbon combustion mode.

Advantageously, the change in the fall below a second predetermined, characteristic of the amount of carbon excess in the reaction chamber value is reversed. That is, as soon as it is detected that a sufficient amount of excess carbon is burned and the carbon amount has no more critical value, is switched back to the "normal" operating state of the reactor, thereby ensuring that the operating state for the combustion of excess carbon, temporarily a lower Efficiency, as the normal operating state designed for optimum gasification, is maintained only for a minimal time, but just long enough to sufficiently ensure removal of carbon.

The determination of excessive carbon surplus in the reactor is made on the basis of a value characteristic of the amount of carbon surplus. Here, a variety of values can be used. However, it is particularly advantageous if in each case a predetermined pressure difference across a gas-permeable retention device between the reaction chamber and an ash box of the gasification reactor is used as such a value. Namely, a carbon excess will preferentially deposit on such a retainer. As a result of the adhesive properties of the excess carbon, the gas permeability of the retaining device is reduced, and the useful gas produced in the reaction chamber can thus escape more poorly. This increases the pressure difference across the retaining device, which is relatively easy to detect with corresponding pressure sensor. This is a simple yet reliable measure of the amount of excess carbon in the reaction chamber. The main accumulation of excess carbon in the retention device described allows a further optimization of the method. In an advantageous embodiment, the composition, amount, pressure, velocity, temperature and / or specific exit pulse of one of the reaction chambers in the region of a gas-permeable retention device between the reaction chamber and the or an ash box the gasification reactor added added gasifying agent. Thus, in particular in the area of increased accumulations of carbon surplus, the operating parameters are changed in such a way that the carbon is gasified here. This also makes it possible to maintain the gasification reaction under normal operating conditions in other areas where the accumulation of carbon is less high.

In a particularly simple manner, the combustion of carbon can be achieved by advantageously increasing the amount of added gasification agent. A larger amount of oxygen allows the oxidation of the carbon.

In a further advantageous embodiment, the water vapor content in the gasification agent is reduced. This reduces the energy-consuming reduction reaction, increases the temperature and thus promotes combustion of carbon.

The features of the method described so far can be realized via predetermined operating parameters with regard to the addition of gasification agent, etc. Thus, e.g. set two sets of operating parameters, one for the gasification and one for the carbon combustion operation, between which then, if necessary, according to the described method is redesigned.

In a particularly advantageous embodiment, however, the method is embedded in a higher-level control, wherein the reaction chamber thereby (preferably has multiple) control inputs and composition, amount, pressure, speed, temperature and / or specific exit pulse of the gasification agent are variably controlled by a number of determined in the reaction chamber controlled variables. In the case of several control inputs, the gasification agent added via the respective control input is advantageously at least partially controlled independently of the respective other control inputs. Consequently, during operation of the gasification reactor, several, ideally every position within the reaction chamber are accessible through these control inputs. Each individual control input thus defines a reaction zone, all reaction zones thereby forming the reaction space which completely fills the reaction chamber.

Since the control inputs are at least partially controlled independently of one another, in each reaction zone of the reaction space, the addition of gasification agent with respect to its composition, speed, temperature, pressure and amount as well as with respect to the specific exit pulse is variable over time.

In terms of design, this can be realized in that the side walls of the reaction chamber are interspersed with a multiplicity of such control inputs or that a holder with a plurality of recessed control inputs projects into the reaction chamber. Depending on the predominant nature of the carbonaceous fuel in conjunction with the geometry of the reaction chamber, especially if the diameter of the reaction chamber is greater than the height, the combination of both constructive ways for the arrangement of the control inputs proves to be advantageous, whereby the accessibility of the entire reaction space is guaranteed.

Throughout the gasification process, the nature of the fuel material changes. In particular, in the gasification of solid, carbonaceous fuel materials in a DC fixed-bed gasification reactor constructed according to the invention, a gas phase decreasing from the lower to the upper part of the reaction chamber is formed in the course of the gasification process. 8 kohlungsgradient off. Therefore, in the progressing gasification process in the lower reaction zones for gasification of the resulting pure carbon increased water vapor is supplied together with the hot reactor internal gas. In this case, C0 ₂ can be regarded as a gasification agent itself from 600 ° C itself, since then its equilibrium reaction with carbon according to Boudouard to 23% on the side of CO. In summary, therefore, the gasification agents comprise at least one of the components O ₂ or H ₂ O, wherein the gasification agent CO ₂ is generated during the gasification process itself.

Since the gasification process of solid, carbonaceous fuel materials in accordance with the invention carried out DC fixed bed gasification reactors is determined by a predominantly vertically extending reaction gradient, a structural simplification is possible. This constructive simplification is that the control inputs are thus combined horizontally into two-dimensional, but independent, reaction zones by being connected horizontally by ring lines, which in turn circulate the gasification reactor or the reaction chamber. Here, in turn, in each planar reaction zone of the reaction chamber, the addition of gasification agent or the return of the reactor internal gas with respect to composition, temperature and pressure and thus quantity variable over time.

The regulation described now makes it possible not to achieve the combustion of carbon by setting predetermined combustion parameters, but by prescribing one or more setpoint values for the respective control variables. As a result, the higher-level control is maintained and the operation can be optimally maintained even in the combustion operating state.

In an advantageous embodiment of the setpoint temperature is changed as a controlled variable. Such a change is answered by the regulation accordingly with an increase in the amount of combustion agent and the reduction of the water vapor content, since these measures increase the temperature. The embedding of the method described in a higher-level control also allows in a particularly simple manner, the maintenance of the gasification in areas of the reaction chamber with lower carbon deposits. Advantageously, to a control input, which is located outside the range of gas-permeable retention device between the reaction chamber and the ash box of the gasification reactor, the target value of the temperature is reduced as a controlled variable. As a result, the gasification is continued here, while in the region of the retaining device, the carbon combustion takes place.

In a further advantageous embodiment of the method upon detection of the carbon excess, i. when the predetermined value is exceeded, the amount of fuel supplied to the reaction chamber is reduced. As a result, the fuel content is temporarily reduced in the reaction chamber, since the gasification initially continues. This promotes easier combustion of carbon.

In summary, the inventive method allows optimal and accelerated removal of carbon excesses in the reaction chamber by the controlled and the course adapted switching to a combustion-promoting operating state.

The controlled combustion of carbon by temporally and locally individually metered addition of gasification agents in the gasification reactor on which the invention is based replaces the extremely energy-conserving maintenance of the fluidized bed required for the Winkler generator for optimal and condensate-free gasification of the fuels.

Overall, the method provides a stable and completely autothermal operation of the gasification reactor according to the invention with a high overall efficiency, in particular as a subsystem of a CHP. Finally, the method according to the invention is particularly advantageous over all embodiments of vortex and entrained flow gasification reactors in that each type and form of carbonaceous fuel material can be used in any state of aggregation for gasification. For example, a DC fixed bed reactor designed according to the invention may additionally have a gas feed device in the reaction chamber. Also, plastic waste and household waste as an example of extremely inhomogeneous mixtures of carbonaceous fuel materials can be gasified with a high overall efficiency in a DC fixed bed reactor according to the invention. Much finer-grained wood chips may also be used instead of the traditionally used coarse-grained chips, since the blockage of the reactor caused by the use of the cheaper fine-grained fuel can be eliminated by the described method.

The invention will be explained in more detail with reference to two embodiments with reference to the drawing figures. Show it:

1 is a gasification reactor with loops,

2 shows a gasification reactor with central hedgehog-type supply line,

Fig. 3 is a schematic representation of the control and control variables in the case of involvement in a scheme with their mutual influence and

4 is a schematic representation of the different operating states for gasification and carbon combustion.

Identical parts are always provided with the same reference numerals.

The embodiment in Fig. 1 relates to a gasification reactor 1, which is designed in particular for the gasification of solid carbonaceous fuel. For this purpose, the gasification reactor 1 is designed as a fixed bed reactor according to the DC principle. The gasification reactor according to FIG. 1 is suitable for carrying out the process according to the invention. The gasification reactor 1 has a permeable intermediate bottom 2, which divides the gasification reactor 1 into an upper reservoir 3 and into a lower reaction chamber 4. Another permeable intermediate bottom 5 separates the reaction chamber 4 from the ash box 6 as the lowest subspace of the entire gasification reactor 1 from. A gas-permeable retention device 7 in the form of a grate between the reaction chamber 4 and the ash box 6 ensures that the fuel remains in the reaction chamber 4. At the ash box 6, a gas outlet 8 is attached. Via the reservoir 3, the carbonaceous, solid fuel is fed to the reaction chamber 4, the useful gas is discharged via the gas outlet 8. After filling reservoir 3 and reaction chamber 4 with the carbonaceous, solid fuel material, the gasification reactor in the lower reaction zones is ignited once and then started up by supplying air.

The side wall 9 of the reaction chamber 4 of the gasification reactor 1 is interspersed with a plurality of control inputs 10 in such a way that in the operation of the gasification reactor each position within the reaction chamber 4 is accessible through the control inputs 10. The control inputs 10 are horizontally over the reaction chamber circulating ring lines 11 to flat, but summarized independent reaction zones. By the respective independent ring lines 11 the addition of gasification agent or the return of the reactor internal gas with respect to composition, temperature and pressure and thus quantity is then controlled via the combined via web connections 12 control inputs 10. The control is individual for each area reaction zone.

The reservoir 3 of the gasification reactor 1 has a larger diameter and a larger volume than the reaction chamber 4, wherein the permeability of the intermediate bottom 2 is given by an opening with a diameter which is smaller than that of the reservoir 3 and the reaction chamber 4, but greater than the opening of the intermediate bottom 5 is. The reactor with its reservoir 3, the reaction chamber 4 and its ash box 6 are cylindrical, the openings of the shelves 2 and 5 are circular. This outg

is Design of the gasification reactor 1 allows its embedding in a fully enclosing insulation, whereby the reactor efficiency is further increased. Regarding the stability in its construction, the gasification reactor 1 is designed to withstand deflagration of the gasification products as well as the fuel.

The gasification reactor 1 according to FIG. 2 likewise has an upper reservoir 3 and a permeable intermediate bottom 2. The reaction chamber 4 is charged by nozzle-shaped nozzle entrances 13. In the exemplary embodiment according to FIG. 2, the nozzle inlets 13 form the control inputs 10 of the gasification reactor 1. Otherwise, the gasification reactor 1 according to FIG. 2 corresponds in its construction to that in FIG. 1.

The control variables determined via the control inputs 10 of the gasification reactor together with the control variables influencing the gasification agent are shown in FIG. Control parameters that can be directly influenced by the control are here the total amount of gasification agent 20, the admission pressure 22 of the gasification agent at the nozzle or control inputs 10, 13, the respective distribution 24 of the gasification agent to the individual nozzle or control inputs 10, 13, that of a spatial distribution corresponds to the temperature 26 of the gasifying agent and the water vapor content 28 in the gasification agent.

As measured in the reactor 1 controlled variables are detected: the flow 30 of the generated Nutzgases, the differential pressure 32 on the lower shelf 5, the chemical Nutzgaszusammensetzung 34, the pressure 36 in the reaction chamber 4, the temperature 38 in the reaction chamber 4 at the respective control input 10 and the type of reactions occurring 40. The latter can typically not be measured directly but can only be determined as a derived controlled variable.

FIG. 3 now shows the respective relationships between control variables and control variables, as required in the method according to the invention when incorporated into a control: the volume flow 30 of the useful gas is influenced by the total amount of gasification agent 20, since an increased supply of gaseous gasification agent increases the volume flow through the entire reactor 1. Furthermore, it is influenced by the water vapor fraction 28 in the gasification agent, since introduced water vapor is hydrolytically split and thus causes an increase in the volume and thus the volume flow 30 of the exiting useful gas.

The differential pressure 32 across the retention device 7, which is permeable to gas, is essentially an indicator of increased deposition of carbon residues blocking the gas flow rate of the retention device 7. Carbon remains at lower temperatures when the carbon is not burned. This is particularly the case with a high water vapor content 28. Thus, the water vapor fraction 28 influences the differential pressure 32. If the distribution 24 of the supplied gasification agent is changed such that at control inputs 10 in the region of the retaining device 7 more gasification agent is introduced and the temperature increases here, Thus, the accumulated carbon is burned and the differential pressure 32 decreases. This will be explained in more detail below.

The gas composition of the useful gas 34 depends essentially on the proportion of the water vapor 28. A higher amount of water vapor leads to a higher proportion of hydrogen in the useful gas.

The pressure 36 in the reactor chamber 4 should not deviate too far from the ambient pressure. It is essentially influenced by the total quantity 20 of the gasification agent supplied, and also by the spatial distribution 24 of the gasification agent.

The temperatures 38 in the various regions of the reactor chamber 4 are influenced above all by the spatial distribution 24 of the gasification agent, but also by admission pressure 22 and temperature 24 of the gasification agent, as well as the water vapor fraction 28 in the gasification agent, as explained above. The type of chemical reactions occurring 40 is also, as already explained, essentially determined by the water vapor content 28 in the gasification agent, and also by the temperature of the introduced gasification agent.

The described control is active during the operation of the reactor 1. If required, a targeted combustion of carbon is now initiated when a too high differential pressure 32 is detected, a limit being specified for this purpose. The goal here is a temperature increase in the area of the retention device 7. This can be achieved either by specifying appropriate temperature setpoints with active control, or by direct control of the supplied gasification agent. The resulting temperature profile is shown in FIG. 4.

4 shows a characteristic of the two operating conditions temperature profile within the reaction chamber 4. In this case, the vertical axis of the reaction chamber is plotted on the abscissa, the upper area is left with the fuel supply to the left, while the right is the lower area with the retaining device 7. The lines 42 each indicate the location of the independently controllable control inputs 10, the line 44 marks the rough distinction in more (right) and less (left) areas affected by carbon surplus deposits.

Line 46 indicates the maximum temperature distribution to be maintained by the control and line 48 the minimum thereof to ensure smooth operation of the reactor 1. Within the limits 46 and 48, the temperature is now adapted to the two operating states.

Temperature line 50 shows the temperature distribution during normal operation. In the lower part of the temperature is the lowest, to ensure an optimal composition of the Nutzgases. In the upper area the temperature is comparatively high. In the lower area, but here it can be a Excess carbon come, which deposits on the restraint device 7. This is determined in the form of an increase in the pressure difference 32.

If a specified limit value is exceeded, the system is switched to the freewheeling operating state. The resulting temperature distribution represents temperature line 52. In the upper region, the temperature is now lower, while in the lower region, i. at the restraint device 7 almost increases to the given by line 46 maximum. As a result, carbon is oxidized here. Once the retaining device 7 is again free of carbon, which is determined by falling below a predetermined limit value of the pressure difference 32, the temperature line 50 is switched back to the normal state.

The controlled switching to the freebearing operating state according to the method according to the invention, taking into account the control which takes into account the control variables recorded in the reactor 1, sets the control variables as required for optimized combustion of excess carbon. The gasification reactor 1, operated with a method under control of the variables described in this embodiment is designed for a CHP, so for the heat and power. Through thermal integration of all subsystem units of the entire system, combined heat and power generation achieves an overall efficiency of> 85%.

LIST OF REFERENCE NUMBERS

1 gasification reactor

2 intermediate floor

3 reservoir

4 reaction chamber

5 intermediate bottom

6 ash box

7 restraint device

8 gas outlet

9 side wall

10 control input

11 ring line

12 bridge connection

13 nozzle entrance

20 total gasification amount

22 form

24 distribution

26 temperature

28 water vapor content

30 volume flow

32 differential pressure

34 useful gas composition

36 pressure

38 temperature

40 reaction type

42 line

44 line

46 line

48 line

50 temperature line

52 temperature line

Claims

claims

1. A method for the automatic removal of an excess of carbon in a gasification reactor (1) with a reaction chamber (4) for the autothermal and / or allothermal gasification of carbonaceous fuel to useful gases,

characterized,

in that, when a predetermined value characteristic of the amount of carbon excess in the reaction chamber (4) is exceeded, the composition (28), amount (20), pressure (22), velocity, temperature (26) and / or specific exit pulse of one of the reaction chambers ( 4) added gasifying agent can be changed such that a combustion of the excess carbon is enhanced.

2. The method according to claim 1,

characterized by

that the change is reversed when a second predetermined value characteristic of the amount of carbon excess in the reaction chamber (4) is fallen short of.

3. The method according to claim 1 or 2,

characterized by

in that in each case a predetermined pressure difference (32) via a gas-permeable retention device (7) between the reaction chamber (4) and an ash box (6) of the gasification reactor (1) is used as characteristic value for the amount of carbon excess in the reaction chamber (4).

Method according to one of claims 1 to 3,

characterized by

that composition (28), amount (20), pressure (22), speed, temperature (26) and / or specific exit pulse of one of the reaction chamber (4) in the region of a gas-permeable retention device (7) between the reaction chamber (4) and the or an ash box (6) of the gasification reactor (1) added gasifying agent can be changed.

Method according to one of claims 1 to 4,

characterized by

that the amount (20) of the added gasifying agent is increased.

Method according to one of claims 1 to 5,

characterized by

a water vapor content (28) of the added gasification agent is lowered.

Method according to one of claims 1 to 6,

characterized by

the gasification agent is fed to the reaction chamber via control inputs (10) and the composition (28), quantity (20), pressure (22), velocity, temperature (26) and / or specific exit pulse of the gasification agent are variably determined by a number of in the reaction chamber ( 4) determined control variables (30, 32, 34, 36, 38, 40) are controlled, wherein when exceeding the predetermined value, the desired value of a controlled variable (30, 32, 34, 36, 38, 40) is changed.

Method according to claim 7,

characterized by

that the controlled variable (30, 32, 34, 36, 38, 40) is the temperature (38) and that the setpoint is increased.

Method according to claims 7 or 8, characterized by

that at a control input (10), which is arranged outside the region of the gas-permeable retention device (7) between the reaction chamber (4) and the ash box (6) of the gasification reactor (1), the desired value of the temperature (38) as controlled variable (30, 32, 34, 36, 38, 40) is lowered.

10. The method according to any one of claims 1 to 9,

characterized by

that when exceeding the predetermined value, the amount of the reaction chamber (4) supplied fuel is reduced.

Gasification reactor (1) with means for carrying out the method according to nem of claims 1 to 10.