DE102011119386A1 - Method for starting and stopping a gasification plant - Google Patents

Abstract

A method for starting up a gasification plant comprising a gasification reactor (1) with a reaction chamber (4) for the autothermal and / or allothermal gasification of carbonaceous fuel to Nutzgasen should reduce the release of environmentally harmful gases to a minimum and can be automated. For this purpose, the method comprises the method steps: filling the reaction chamber (4) with carbonaceous fuel; - initiation of a combustion process; Maintaining the combustion process by adjusting a stoichiometric or superstoichiometric air to fuel ratio in the reaction chamber (4); and - initiation of a gasification process by adjusting a sub-stoichiometric air-fuel ratio in the reaction chamber (4) after reaching a predetermined desired operating temperature.

Description

The invention relates to methods for starting and stopping a gasification plant comprising a gasification reactor with a reaction chamber for the autothermal and / or allothermal gasification of carbonaceous fuel to Nutzgasen.

Technical background

Gasification plants and gasification reactors are used to obtain useful gas from solid, carbonaceous fuel, with which, for example, an internal combustion engine can be operated to generate electricity. Such a gasification reactor with a method of operating it is, for example, not yet published German patent application 10 2011 117 141 The disclosure of which is expressly incorporated herein by reference.

In addition to the gasification reactor, such a gasification plant usually has a filter for cleaning the recovered Nutzgases and an internal combustion engine for generating mechanical energy from the Nutzgas. The useful gas is thus passed directly from the reaction chamber of the gasification reactor via the filter in the internal combustion engine.

The gasification reactor operates during operation with a substoichiometric air to fuel ratio, i. H. with less air than needed to completely burn the fuel. A complete combustion is not desirable here, but still combustible gas should be obtained. This also creates environmentally harmful gases that must not penetrate into the atmosphere.

During operation of the gasification plant this is not a problem, since the resulting gases are typically filtered directly and then fed into the internal combustion engine, where a complete combustion to non-toxic, inert gases takes place. The problem, however, is the formation of such gases when starting and stopping the gasification plant.

So far, a gasification reactor is typically started up in the substoichiometric state up to the operating temperature of all components. During the start-up phase, an operation of the internal combustion engine is not yet possible, so that large amounts of gas are released, which on the one hand does not comply with the legal requirements and on the other leads to great odor nuisance. In the prior art, therefore, torches are used which burn the gas produced by the reactor. However, this is expensive and expensive, since it must be ensured that too low gas concentrations can be safely burned even for self-firing. This would require a support fire in the torch.

Also in the Abfahrphase the amount of gas obtained can fall below the amount necessary for the operation of the engine, so that a further operation of the engine is no longer possible and the gas leaks, with the disadvantages described above. This is particularly critical in an emergency operating situation, z. B. in case of failure of the engine.

Task and solution

The invention is therefore based on the object to provide methods for starting and stopping a gasification plant, which reduce the release of polluting gases to a minimum and can be automated. This object is achieved in each case by the combination of features of claims 1, 6, 7 and 9 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 a gasification plant comprising a gasification reactor with a reaction chamber for the autothermal and / or allothermal gasification of carbonaceous fuel to Nutzgasen, and optionally a gas outlet of the reaction chamber downstream engine.

In the reaction chamber, the carbonaceous fuel is in normal operation. 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 in normal operation predominantly in the reaction chamber. The gasification reactor according to the invention can also be designed completely as a reaction chamber.

• – Befüllen der Reaktionskammer mit kohlenstoffhaltigem Brennmaterial;
• – Einleitung eines Verbrennungsprozesses;
• – Erhaltung des Verbrennungsprozesses durch Einstellen eines stöchiometrischen oder überstöchiometrischen Luft-zu-Brennmaterial-Verhältnisses in der Reaktionskammer; und
• – Einleitung eines Vergasungsprozesses durch Einstellen eines unterstöchiometrischen Luft-Brennmaterial-Verhältnisses in der Reaktionskammer nach Erreichen einer vorgegebenen Betriebssolltemperatur.

As an essential feature of the invention, the method for starting up the gasification plant according to claim 1 comprises the following method steps:

• - filling the reaction chamber with carbonaceous fuel;
• - initiation of a combustion process;
• Maintaining the combustion process by adjusting a stoichiometric or superstoichiometric air to fuel ratio in the reaction chamber; and
• - Initiation of a gasification process by adjusting a substoichiometric air-fuel ratio in the reaction chamber after reaching a predetermined operating temperature.

By such a process, the gasification reactor is not started in the gasification operation, d. H. with a stoichiometric air-to-fuel ratio, but rather in superstoichiometric operation, where the fuel is completely burned and so no harmful gases escape. In addition, a faster heating of the reactor is achieved.

If a predetermined desired operating temperature is reached, in which the gasification reactor is ready for operation, a substoichiometric air-to-fuel ratio is set by appropriate adjustment of supplied air and fuel quantity and thus switched to the regular gasification operation, is generated in the useful gas.

Advantageously, the maintenance of a stoichiometric or superstoichiometric air to fuel ratio in the reaction chamber during reactor warm-up is controlled by controlling the amount of carbonaceous fuel feed. In particular, the amount of fuel supplied should be so small that there is always an excess of air.

Advantageously, the oxygen content of the exhaust gas exiting the gas outlet device of the reaction chamber is used as a controlled variable. If this decreases, less fuel is supplied or the supply is stopped; if the oxygen content is too high, more fuel is supplied.

In a further advantageous embodiment of the method, the carbonaceous fuel is supplied asymmetrically to the reaction chamber. As a result, a portion of the reaction chamber remains unfilled, leaving enough room for the passage of air. This improves the aeration of the reaction chamber and promotes combustion in the over-stoichiometric air-to-fuel ratio.

Advantageously, exhaust gas of the reaction chamber exiting from the gas outlet device is cooled by means of a heat exchanger. As a result, the efficiency of the system is improved. The heated flow medium from the heat exchanger can also be used for preheating other components of the gasification plant.

An essential feature of the invention is in the method for starting the gasification plant according to claim 6, a gas outlet device of the reaction chamber downstream engine after initiation of a gasification process by means of an asynchronous generator, in particular with a soft starter and / or inverter is started.

Since time immemorial, one has problems with the start of the internal combustion engine in wood gasification plants. Normally starters are used for this purpose. Due to the possibly not yet optimal gas quality at the beginning and the fact that the internal combustion engine only has to suck the gas out of the reactor, and it is virtually produced in the process, the light-off is difficult and reliably automated.

To solve this problem, the invention proposes an asynchronous generator with soft starter and / or inverter. For this purpose, the internal combustion engine is driven instead of the starter via the asynchronous generator, which now works as a motor and is powered by the power grid. The soft starter now ensures that the asynchronous generator can be accelerated slowly. The use of a soft starter for an asynchronous generator is also advantageous, since from a certain size these machines can no longer start directly from the mains. A converter makes it possible to operate the asynchronous generator independently of the speed on the power grid.

In contrast to the starter, which accelerates the internal combustion engine only to approx. 200 rpm, the soft start can reduce the internal combustion engine to 1500 rpm, i. H. Speed up synchronous speed. In contrast to the starter, which can only accelerate the engine for a few seconds, the internal combustion engine can be operated permanently by the asynchronous generator functioning as a motor. The resulting induced draft in the intake tract of the engine now allows the upstream gas generating plant to produce rapidly combustible gas after the corresponding valves have been opened.

As combustible gas arrives at the internal combustion engine, the combustion now taking place in the engine helps the asynchronous generator functioning as a motor to maintain the speed of 1500 rpm. Finally, the internal combustion engine via the fuel gas supplied to it is able to deliver more torque on its shaft than would be necessary to cover its friction losses, so that no power from the power supply via the functioning as a motor asynchronous generator is more needed. The internal combustion engine begins to drive the asynchronous generator and thus energy into the Supply power. Thus, the internal combustion engine has arrived in its normal operating condition. The asynchronous motor now operates in generator mode.

• – Beenden der Zufuhr von kohlenstoffhaltigem Brennmaterial zur Reaktionskammer (4);
• – Trennen der Gaszufuhr von der Gasaustrittseinrichtung (6) zum Verbrennungsmotor sobald die Leistung des Verbrennungsmotors unter einen vorgegebenen Grenzwert sinkt; und
• – Abstellen des Verbrennungsmotors.

As an essential feature of the invention, the process for driving off the gasification plant according to claim 7 comprises the following process steps:

• Terminating the supply of carbonaceous fuel to the reaction chamber ( 4 );
• Separating the gas supply from the gas outlet device ( 6 ) to the internal combustion engine as soon as the power of the internal combustion engine falls below a predetermined limit; and
• - Shut down the internal combustion engine.

By such a method it is guaranteed that all useful gases generated in the reaction chamber actually get into the internal combustion engine, so that they are burned and do not escape into the environment.

Advantageously, a predetermined minimum rotational speed of the internal combustion engine is obtained by means of an asynchronous generator until the internal combustion engine is switched off. As a result, further gas can be removed from the system by sucking in the internal combustion engine even if the gas quantity is no longer sufficient for operating the internal combustion engine.

• – Erkennen eines Notbetriebszustandes;
• – Beenden der Zufuhr von kohlenstoffhaltigem Brennmaterial zur Reaktionskammer; und
• – Luftdichtes Verschließen der Reaktionskammer.

As an essential feature of the invention, the process for emergency shutdown of the gasification plant according to claim 1 comprises the following process steps:

• - detecting an emergency operating state;
• Terminating the supply of carbonaceous fuel to the reaction chamber; and
• - Airtight closing of the reaction chamber.

The emergency shutdown is z. B. necessary if the gasification system is off the grid, the engine is no longer running or in a safety incident such. B. a power failure. These are examples of an emergency mode.

In the event of a power outage, compressed air failure or other serious failure in which the gas can no longer be burned in the engine, the gas is virtually frozen by the airtight closure provided in the process. The fuel supply and the air supply are stopped and the system is completed so that only a still resulting from outgassing pressure is discharged through a chimney. Since no more air can penetrate into the system, no exhaust gas can escape to the fireplace, unless there is gas in the system. However, as temperatures in the reactor rapidly subside, this is only the case for a very short period of time. There is no dangerous release of gas, no odor nuisance occurs. The system cools down and can then be rinsed.

Advantageously, the reaction chamber is charged with an inert gas. This is advantageously carried out with the other components of the gasification plant. This significantly reduces the risk of uncontrolled combustion in the system or explosion. Inert gases can be used in particular CO ₂ .

In an advantageous embodiment, a gasification reactor is operated with the mentioned method.

The advantages achieved by the invention are, in particular, that gas leaks of useful gas are safely minimized by the proposed method for transient operating conditions of the gasification plant. The system is safely started and stopped.

The invention will be explained in more detail with reference to a drawing. Show it:

1 a gasification reactor with ring pipes,

2 a gasification reactor with central igelartiger supply, and

3 a schematic representation of a gasification plant.

Identical parts are always provided with the same reference numerals.

The embodiment in 1 refers to a gasification reactor 1 , which is designed in particular for the gasification of solid carbonaceous fuel. This is the gasification reactor 1 designed as a fixed bed reactor according to the DC principle.

The gasification reactor 1 has a permeable intermediate floor 2 on top of the gasification reactor 1 in an upper reservoir 3 and in a lower reaction chamber 4 divided. Another permeable intermediate floor 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 provides a fate of the fuel in the reaction chamber 4 for sure. At the ash box 6 is a gas outlet 8th appropriate. About the reservoir 3 becomes carbonaceous, solid Fuel of the reaction chamber 4 supplied, the useful gas is via the gas outlet 8th dissipated. After filling reservoir 3 and reaction chamber 4 with the carbonaceous, solid fuel, the gasification reactor is ignited once in the lower reaction zones and then started by supplying air.

The side wall 9 the reaction chamber 4 of the gasification reactor 1 is with a variety of control inputs 10 interspersed in the manner that in the operation of the gasification reactor each position within the reaction chamber 4 through the control inputs 10 is accessible. The control inputs 10 are horizontal over the reaction chamber circulating ring lines 11 combined into two-dimensional but independent reaction zones. Through the respective independent ring lines 11 is then via the via jetty connections 12 summarized control entries 10 Controlled the addition of gasification agent or the return of the reactor internal gas with respect to composition, temperature and pressure and thus amount. 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 false floor 2 is given through an opening with a diameter smaller than that of the reservoir 3 and the reaction chamber 4 but larger than the opening of the false floor 5 is. The reactor with its reservoir 3 , the reaction chamber 4 and with his ash box 6 are cylindrical, the openings of the shelves 2 and 5 circular. This embodiment 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 is the gasification reactor 1 designed to withstand deflagration of both the gasification products and the fuel.

The gasification reactor 1 according to 2 also has an upper reservoir 3 and a permeable false floor 2 on. The reaction chamber 4 is fed by hedgehog-shaped nozzle entrances 13 , The nozzle entrances 13 form in the embodiment according to 2 the control inputs 10 of the gasification reactor 1 , Incidentally, the gasification reactor corresponds 1 according to 2 in its construction to that in 1 ,

The gasification reactor in this embodiment is designed for a CHP, so for the heat and power. A schematic, simplified representation of such a gasification plant 20 shows 3 ,

In the gasification plant 20 is the gasification reactor 1 at the gas outlet 8th a filter 22 downstream, in which the gas is cleaned. The filter 22 will be over a valve 24 Filter air supplied. The purified gas is discharged from the filter and can either be a chimney 26 via a valve 28 or an internal combustion engine 30 over another valve 32 be supplied. Depending on the operating state, the valves become 28 . 32 closed or opened, as will be described below. The shaft of the internal combustion engine 30 is with an asynchronous generator 34 connected, which has a soft starter.

With the illustrated gasification plant 20 can now be ensured by appropriate procedures in transient operating conditions that no harmful gas enters the environment and a particularly high operational safety is guaranteed.

The start of the gasification plant 1 is triggered in the system control by user selection. Thereafter, the process controller performs a self-test of all components. If this self-test is successfully completed, then the gasification plant 1 rinsed to remove any existing gas residues. For this purpose, the - not shown - Kamingebläse put into operation and the gas path to the fireplace 26 switched over, ie the valve 32 closed and the valve 28 open.

Subsequently, the gasification reactor 1 filled with fuel up to a suitably selected filling level and ignited manually or automatically via an ignition device. The gasification reactor 1 and the downstream filter 22 warm up. The air required for the superstoichiometric combustion passes through an air opening provided for this purpose in the upper area in the gasification reactor 1 ,

Subsequently, a lambda control takes over the automatic supply of fuel, so that the gasification reactor is always kept in the superstoichiometric range (that is, excess air). In this condition, the system works in principle as a furnace. The resulting heat is used by the furnace exhaust gas is cooled by - not shown - heat exchanger and the thus heated water is used for heating.

The operating condition described above is referred to as superstoichiometric operation or furnace operation. So that this operating state can be optimally driven, the fuel is introduced asymmetrically into the gasification reactor, thus always part of the restraint device 7 are free for the passage of air. The air is supplied from above. At the same time, the level of the reactor becomes so regulated that there is always excess air. For this purpose, the oxygen content in the exhaust gas is measured. If this decreases, less fuel is supplied or the supply is stopped; if the oxygen content is too high, more fuel is supplied.

For the further starting process, the filter 22 brought to operating temperature by means of furnace operation of the gasification reactor. The operating temperature is thus achieved without generating harmful or toxic gases.

When these operations are completed, the plant control switches from furnace operation to gasification operation. After switching, the fuel supply is increased by the plant control until sub-stoichiometric conditions prevail in the reactor, ie. H. the fuel is no longer completely burned. The gasification begins.

If this is the case, the internal combustion engine can 30 automatically via the soft start on the asynchronous generator 34 started and the gas path from the fireplace 26 on the internal combustion engine 30 be switched, ie valve 32 opens, valve 28 closed. By using an inverter, the asynchronous generator can 34 also be fed with lower speeds from the public grid. Through continuous increase in performance of the combustion engine 30 the asynchronous generator arrives 34 from motor to generator operation.

After the internal combustion engine 30 is now in operation, the power is automatically increased and activated by the control various control circuits. Are all control loops active and the power of the internal combustion engine? 30 sufficiently high, so goes the gasification plant 20 in the fully automatic CHP operation over.

To shut down the gasification plant 20 , the Z. B. is necessary for performing scheduled maintenance, the following steps are provided: The Abfahrvorgang begins with the selection of the Abfahrroutine in the process control. Thereupon, the control of the fuel supply from the container in the fuel input of the gasification reactor 1 stopped, all feeder facilities such. B. conveyors and the fuel input are emptied. Subsequently, the filter air supply to the valve 24 closed and the - not shown - tube cooler activated to 100%. In addition, the power of the CHP is continuously reduced.

When the gasification reactor 1 not enough wood gas for the internal combustion engine 30 this falls into reverse load, ie it is from the now acting as an engine asynchronous generator 34 driven. If this is the case, the gas path through the process control from the internal combustion engine 30 on the fireplace 26 switched, ie valve 32 closed and valve 28 open. The internal combustion engine 30 is then turned off. The remaining waste gas of the gasification reactor 1 escapes through the fireplace 26 and the system cools down.

If the CHP is disconnected from the mains, the engine is no longer running or in the event of a safety fault, such as a As a power failure, a quick emergency shutdown is necessary, which reliably prevents an inadmissible gas leakage.

In the event of a power outage, compressed air failure, or other serious disruption that can no longer burn the gas in the engine, the gas will not go over the chimney 26 drained, but the gasification plant 20 "Frozen", ie the fuel supply and the air supply are stopped and the gasification plant 1 so hermetically sealed that only a still resulting from outgassing pressure through the chimney 28 is derived. In addition, the entire gasification plant 1 rendered inert with CO2. There is no more air in the gasification plant 1 can also penetrate, no exhaust gas to the fireplace 26 Escape, unless it arises gas in the gasification plant 1 , As the temperatures in the gasification reactor 1 however, it quickly fades for a very short period of time. The system cools down and can then be rinsed.

The described method ensures in every transient operating state that no dangerous release of gas can occur and no odor nuisance occurs.

LIST OF REFERENCE NUMBERS

1

gasification reactor

2

false floor

3

reservoir

4

reaction chamber

5

false floor

6

ash tray

7

Restraint

8th

gas outlet

9

Side wall

10

control input

11

loop

12

web connection

13

nozzle inlet

20

gasification plant

22

filter

24

Valve

26

fireplace

28

Valve

30

internal combustion engine

32

Valve

34

Induction

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102011117141 [0002]

Claims (11)

Process for starting up a gasification plant comprising a gasification reactor ( 1 ) with a reaction chamber ( 4 ) for the autothermal and / or allothermal gasification of carbonaceous fuel to Nutzgasen, characterized by the process steps: - filling the reaction chamber ( 4 ) with carbonaceous fuel; - initiation of a combustion process; Maintaining the combustion process by adjusting a stoichiometric or superstoichiometric air to fuel ratio in the reaction chamber ( 4 ); and - initiation of a gasification process by adjusting a sub-stoichiometric air-fuel ratio in the reaction chamber ( 4 ) after reaching a predetermined desired operating temperature. Method according to claim 1, characterized in that the maintenance of a stoichiometric or superstoichiometric air-to-fuel ratio in the reaction chamber ( 4 ) is controlled by controlling the supply amount of carbonaceous fuel. A method according to claim 2, characterized in that the oxygen content of the at a gas outlet device ( 6 ) exiting exhaust gas of the reaction chamber ( 4 ) is used as a controlled variable. Method according to one of claims 1 to 3, characterized in that the carbonaceous fuel is supplied asymmetrically to the reaction chamber. Method according to one of claims 1 to 4, characterized in that at the or a gas outlet device ( 6 ) exiting exhaust gas of the reaction chamber ( 4 ) is cooled by means of a heat exchanger. Process for starting up a gasification plant comprising a gasification reactor ( 1 ) with a reaction chamber ( 4 ) for the autothermal and / or allothermal gasification of carbonaceous fuel to Nutzgasen, characterized in that a gas outlet device ( 6 ) of the reaction chamber ( 4 ) downstream combustion engine after initiation of a gasification process by means of an asynchronous generator, in particular with a soft-starting device and / or inverter is started. Process for running a gasification plant comprising a gasification reactor ( 1 ) with a reaction chamber ( 4 ) for the autothermal and / or allothermal gasification of carbonaceous fuel to Nutzgasen, a gas outlet device ( 6 ) of the reaction chamber ( 4 ) downstream combustion engine, and characterized by the steps of: - terminating the supply of carbonaceous fuel to the reaction chamber ( 4 ); Separating the gas supply from the gas outlet device ( 6 ) to the internal combustion engine as soon as the power of the internal combustion engine falls below a predetermined limit; and - stopping the internal combustion engine. A method according to claim 7, characterized in that a predetermined minimum speed of the internal combustion engine is obtained by means of an asynchronous generator until stopping the internal combustion engine. Method for emergency shutdown of a gasification plant comprising a gasification reactor ( 1 ) with a reaction chamber ( 4 ) for the autothermal and / or allothermal gasification of carbonaceous fuel to Nutzgasen, a gas outlet device ( 6 ) of the reaction chamber ( 4 ) downstream combustion engine, and characterized by the method steps: - detecting an emergency operating condition; Terminating the supply of carbonaceous fuel to the reaction chamber ( 4 ); and - airtight closing of the reaction chamber ( 4 ). Process according to Claim 9, in which the reaction chamber ( 4 ) is charged with an inert gas. Gasification reactor ( 1 ) operated by the method according to any one of claims 1 to 10,

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