DE3112975A1 - Process for the continuous generation of fuel gas, and shaft furnace for carrying out the process - Google Patents

Abstract

For the continuous generation of fuel gas from organic material, in particular from organic wastes, the wastes are filled into a shaft furnace through which they migrate by gravity as a dumped layer. In the shaft furnace, the wastes are dried, degassed and gasified with addition of a gasifying agent, an incandescent bed being formed. In order to be able to crack tarry and oily constituents, formed during the gasification, to give volatile compounds, the gasifying agent is introduced above the incandescent bed as a function of the temperature of the latter and passed, together with gases being evolved in the dumped layer, in the direction of flow of the material over the dumped bed through a discharge slot provided for the discharge of the material from the incandescent bed. In this process, the throughput of the material through the discharge slot is controlled in such a way that the material remains above the slot until it has been gasified.

Description

Process for the continuous generation of fuel gas

and shaft furnace for carrying out the method The invention relates refers to a process for the continuous production of fuel gas from organic Material, especially from organic waste in a shaft furnace, which the waste wander through as a layer of bulk material under the action of gravity, whereby they dry, degassed and gasified with the addition of a gasifying agent flowing over a bed of embers as well as a shaft furnace to carry out the process.

The production of fuel gas from wood, coal or coke is known. The fuel gas becomes like a shaft furnace due to incomplete combustion of the goods Executed generator formed in which air, oxygen and / or as gasification agents Steam is introduced. The generated generator gas has combustible gas components essentially carbon monoxide and hydrogen and a small amount of methane on. The remaining gas components of the generator gas are nitrogen and carbon diuxide. The gas generation process is endothermic.

The aim is to generate gas from the generator at the highest possible temperatures to achieve high levels of carbon monoxide and hydrogen at continuous discharge of material from the generator, it is known, the gasification agent to be introduced into the shaft furnace from below. The generated generator gas is at the head removed from the shaft furnace, and must be de-tarred before use as fuel gas.

The object of the invention is to provide a process for continuous production of generator gas in which the organic material is largely degassed and tarry and oily components are cracked into volatile compounds. The gasification process should also be used when processing materials with different Structure and different gasification behavior by controlling a temperature in the ember bed, which leads to the desired gas composition, can be quickly regulated.

This task is performed in a method of the type mentioned at the beginning solved by the measures specified in claim 1. After that, the gasifying agent directly into the bulk material layer above that produced in the shaft furnace Ember bed initiated depending on the temperature in the ember bed. It will be the Amount of gasification agent or its composition, in particular its oxygen, Water vapor or carbon dioxide content, controlled by the reaction temperature in the ember bed. The maximum temperature in the ember bed is preferably at a temperature in the temperature range set between 900 and 1000 ° C. All gases that are in the bulk material layer develop when they are heated, flow through the bulk material layer in Direction of flow of the goods and are over the bed of embers and one for the discharge of the goods are discharged from the discharge gap provided for the ember bed. Above the discharge gap the property is held until it is gassed. It is thus achieved on the one hand that the fuel gas formed flows off directly from the reaction zone at a high temperature, and on the other hand that the organic material is very largely gasified. That generated Fuel gas contains only small amounts of oils or expensive ones. It is beneficial to have a Part of the sensible heat of the fuel gas for preheating the bulk material layer in the regenerative To use heat exchange.

The material to be vasified is preferred after being fed into the shaft furnace Preheated up to approx. 2000C before the gasifying agent is introduced into the bulk material layer is, claim 3. The water vapor produced during heating is with the gasification agent and the gases generated in the bulk material layer via the Ember bed led. The gasification agent is used before entering the bulk material layer expedient as a coolant for a discharge in the shaft furnace, claim 4. The gasification agent is at the same time preheated in a desirable manner.

When gasifying fine-grained material, for example when gasifying from sawdust or rice husks, it has proven to be advantageous for the formation of the bed of embers proven to add at least 10 wt.% Coarse material, claim 5. As a result of different Forms piece size of the goods to be processed an ember bed area consisting of the coarser parts emerges at the discharge gap, which looks like a sieve and only small enough pieces of material that are largely gasified are promoted into the ash tray.

The dimensions of the pieces of the coarse material are selected so that the Good transport in the shaft is not disturbed.

The fuel gas taken from the bed of embers is still over a layer of ash c3eLüllrt at the bottom of the slaughter furnace, where a post-reaction with the remaining carbon takes place.

The features of a shaft furnace for carrying out the invention Process are given in claim 7. The shaft furnace is being gasified Material penetrated under the action of gravity.

The material is heated as it is transported through the shaft furnace. It A bed of embers is formed in the lower area of the shaft furnace, in which a gasification agent is initiated. starting from iliervc n, the trained according to the invention has Shaft furnace has a feed for a gasification agent, which is in the bulk material layer opens above the Glubbett. The flow rate for gasifying agent in the feed is controlled by one depending on the reaction temperature in the ember bed Adjustable regulator. The embers are fed by a conically shaped discharge device supported, which is arranged centrally in the shaft on the ash discharge of the shaft furnace. The discharge device is rotatably mounted and cooled to prevent material overheating to avoid. A discharge gap is created at the lower edge of the discharge device formed, the gap width depending on the forming in the bed of embers Lumpiness of the (; utes and is measured by the required throughput. The gap width is determined so that the residence time of the material to be gasified in the ember bed is sufficient is to largely gasify the material before it is discharged from the bed of embers. The conical shape of the discharge device supports the uniform transport of material to the discharge gap. The product discharge can be regulated by turning the discharge device.

To the intnaiime of the kiln produced in the shaft furnace; ases is at the ash discharge Connect a fuel gas line to the shaft furnace. That in the bulk material layer The gas formed is thus directly from the bed of embers formed in the shaft furnace taken. The fuel gas contains only a small amount of oil and tar. It overflows the fuel gas line preferably in a recuperative heat exchanger, the preheating of the material to be gasified in the shaft furnace is used.

In order to cool the discharge device, preference is given to the in the bulk material layer inflowing gasification agent used, claim 9. Appropriately runs the The gasifying agent is supplied through the discharge device and opens centrally in the shaft, claim 10. A largely homogeneous reaction zone in the shaft furnace to generate the fuel gas is in connection with the central supply of the Gasification means according to claim 11 thereby achieved that the discharge gap as an annular gap between the lower edge of the discharge device and Shaft furnace wall is formed. The gasification agent flows through the reaction zone of the shaft furnace then from i below to outside i The discharge of the largely gasified Material through the conical discharge device is determined by the angle of inclination of the conical surface influenced. The angle of inclination between the base of the discharge device and the conical surface should not exceed 30 degrees and is preferably 20 degrees. To promote the Gutaustrags are according to claim 13 on the conical surface facing the ember bed Guide ribs attached. When the discharge device is rotated, the material is in the Ember bed led from the guide ribs to the discharge gap.

On the discharge device, there are also one or more to the bottom of the Shaft furnace-reaching blades attached when the discharge device is rotated Ashes that collect at the bottom of the shaft furnace are forced to be conveyed to the ash discharge. The burning gas flowing out of the bed of embers draws in over the afterglowing ash Post-reaction with the remaining carbon from Another useful training of the Schaciitofens is specified in claim 15 Thereafter, the bulk material layer above the mouth of the feed for the gasification agent at such a height, that the flow resistance of the bulk material layer o1> outside the Feed is greater than the flow resistance in the feed for the gasification agent.

This is particularly advantageous when used as a gasification agent in the bulk material layer by generating a negative pressure at the mouth of the feed Air is introduced. The higher flow resistance in the bulk material layer above the mouth prevented.

then also in the event that the shaft furnace for the task of too gasifying material is open to the atmosphere, the ingress of secondary air via the bulk material layer into the reaction zone. To regulate the amount of gasifying agent, which is to be introduced into the bulk material layer has the feed for the gasification agent a flow regulator controlled in operative connection with the temperature in the ember bed on, claim 16.

Around the shaft furnace for materials of various structures and with To be able to use different gasification behavior is the discharge device preferably arranged interchangeably in the shaft furnace. Depending on the material to be gasified In this way, discharge devices specially adapted to the material properties can also be used insert.

The invention is explained below using an exemplary embodiment explained in more detail, which is shown schematically in the drawing.

The drawing shows a Schaclitofen 1, the organic to be gasified Material, especially organic waste, via a funnel-shaped material feed 2 can be supplied. A screw conveyor 3 transports the material to the goods entrance 4 of the shaft furnace. In the interior of the shaft furnace, a Bulk material layer 5 is formed.

In the shaft furnace, the material moves under the action of gravity downward. It is in the upper area of the shaft furnace in a preheating zone A of a recuperative heat exchanger 6 heated. In the exemplary embodiment, the heat exchanger 6 in the simplest way by a double-walled, the upper shaft furnace part delimiting Tube formed, the cavity of which is generated by fuel gas as a heating medium in the shaft furnace is flowed through in countercurrent to the direction of flow of the material in the shaft furnace. In the preheating zone A, the material to be gasified is in heat exchange with the fuel gas dried and heated up to approx. 2000C.

In the shaft furnace 1 is a rotatably mounted discharge device from below 7 introduced, which is a bed of embers formed in the lower region of the bulk material layer 5 8 supports. The discharge device 7 is arranged centrally in the shaft and tapered koijsch towards the bulk material layer 5. There is a discharge gap at the lower edge of the cone 9 provided as an annular gap between the cone edge and the shaft furnace wall 1o, the gap width depending on the lumpiness of the goods forming in the ember bed 8 as well is determined by the required throughput. For the gasification of fine material, for example von Reisschaien has a gap between the cone wheel and the shaft furnace wall from about 3 to 5 mm as aLs proved to be favorable. When gasifying fine-grained material at least 10% by weight of coarse material was added. The size of the coarse material is selected so that that bridges in the shaft are avoided. in the ember bed 8 is due to the different piece sizes of the material a sieve-like structure is formed, so that only sufficiently small material particles, which are largely degassed, through the discharge gap 9 are discharged.

Centrally through the discharge device 7 is a feed 11 for Gasification agent performed above the ember bed 8 in the bulk material layer 5 opens. The gasifying agent flowing through the discharge device 7 acts as a Coolant and prevents overheating of the material. At the same time it warms up Gasifying agent before entering the bulk material layer. A cover 12 am The end of the feed line 11 prevents bulk material from entering the feed line. Discharge device 7 and feed 11 form a unit. Via feeder 11 the gasification agent is in a zone designated 1: 3 in the drawing The bulk material layer is in this zone after heat exchange with the fuel gas a temperature of about 2000C. The gasification agent flows together with the water vapor formed during the drying of the material to be gasified as well as with the other gases formed in the bulk material layer in the direction of flow of the goods in a reaction zone B through the bulk material layer and with the formation of fuel gas through the ember bed A fuel gas line discharging the fuel gas 14 is connected to the ash discharge 15 of the shaft furnace. The fuel gas is in the exemplary embodiment deducted from the bed of embers by an induced draft (not shown in the drawing). It flows through the heat exchanger 6 and is there, giving off heat, all of the layers cooled down.

The maximum temperature in the ember bed 8 is preferably at one temperature set in the temperature range between 900 and 1000 ° C. One in the bulk material layer Introduced temperature sensor 16 measures a reference temperature in the shaft furnace above of the ember bed 8, which changes analogously with the reaction temperature in the ember bed. The temperature sensor 16 is in operative connection with a flow controller 17, the is used in the embodiment in the feed 11 for the gasification agent. However, the flow of the gasification fraction in the feed 11 can also be changed in other ways Regulate manner, for example by changing the suction pressure in the fuel gas line 14 or in combination with flow regulator 17 and adjustment of the negative pressure on the Ash discharge 15. If the desired temperature in the ember bed is exceeded, the supply of gasifying agent is throttled; if the temperature drops, the supply is reduced increased by air or oxygen. The temperature of the ember bed can also be changed by the composition of the gasifying agent regulate. With dosed addition of air, oxygen, water vapor or carbon dioxide is a safe one and as a result of the direct supply of the gasification agent into the bulk material layer Above the bed of embers, there is also a rapidly reacting control of the gasification process achieved.

The discharge device 7 has conical elements 18, which in the exemplary embodiment against the base of the cone is indicated by reference numeral 19 in the drawing Have an angle of inclination of 20 degrees.

It has been found in the gassing of fine material that in one such inclination of the conical surfaces of the goods transport and discharge of the goods the ember bed without undesirable compaction of the material and at all points of the discharge gap occurs evenly. On the conical surfaces 18 guide ribs 20 are attached, the When the discharge cone rotates, convey the material in the ember bed to the discharge gap 9. In the exemplary embodiment, the discharge device is operated step-by-step by means of a drive 21 emotional. The discharge device is arranged to be exchangeable.

The gasified material falls through the discharge gap 9 an ash bed 22, which is located on the floor of the shaft furnace below the discharge device 7 trains. The fuel gas flowing out of the bed is used for the post-reaction of the Remaining carbon passed over the ash bed 22 and flows to the ash discharge 15. Shovels 23 attached to the discharge device 7, which lead to the bottom of the shaft furnace are sufficient, also transport when turning the discharge unit 7 forced ash to ash discharge 15.

In the case of a shaft furnace, which, except for the material feed, has a screw conveyor is designed in the same way as the shaft furnace described above, was used for To simplify the material supply, the shaft is left open at the top. But with that no secondary air in through the open shaft through the bulk material layer the reaction zone could penetrate, the height of the bulk material layer in the shaft furnace dimensioned so that the flow resistance of the bulk material layer above the mouth the feed for gasification agent was greater than the flow resistance in the Feed. The inlet was open to the atmosphere. Was used as a gasification agent air is sucked into the bulk material layer of the shaft furnace.

In a shaft furnace of the type described above with a diameter Reiss ehXen of 26o mm and a shaft height of 1 m were mixed with coarser ones Wood particles gassed. The wood particles had a maximum size of about 10 mm on. About 20% by weight of wood particles was added to the rice husks. As a minimum 10% by weight have proven to be favorable Good in the preheating zone B in the heat exchange with generated generator gas up to about 200 0c heated. Air was introduced into the bulk material layer as a gasification agent.

The reaction zone B in the bulk material layer was about 350 mm long. The highest temperature in the bed of embers was 900 to 1000 ° C. The discharge device became gradually with a cycle time of about 2 minutes turned, with about 2 to 3 revolutions taking place in one hour. With a throughput of 12 Up to 15 kg of material to be gasified per hour could be 3o to 40 m³ per hour of fuel gas be generated.

Another shaft furnace with a diameter of 400 mm and a height of 1.5 m was used for the gasification of sawdust, which is also mixed with pieces of wood in the shaft furnace was introduced. The wooden parts had different sizes up to the size of Logs 150 mm long. The reaction zone of this shaft furnace was 450 mm long, the maximum temperature in the bed of embers was 900 to 1000 ° C. The discharge device also made one full revolution 1 to 2 times per hour the end. The cycle time was about 4 minutes. With a throughput of 30 to 40 kg gasifying material per hour, about 100 m³ per hour of fuel gas were generated.

On average, the fuel gas obtained in the shaft furnaces had the following Composition on: 2 vol.% CH4, 15 vol.% H2, 25 vol.% CO, 5 vol. O C0, 53 vol. N2.

The calorific value of the fuel gas was in the range between 5000 and 6000 kJ / m³.

The gasification process can be optimally adjusted by controlling the supply of gasifying agent and regulating the discharge of material. The cone shape and gap width of the discharge device as well as the reaction zone are specified for different materials. fits. In one and the same shaft furnace, materials with a wide variety of structures and different gasification behavior can be added to generate fuel gas by simply exchanging the discharge device.

L e r s e i t e

Claims (17)

Claims 1. A method for the continuous generation of fuel gas from organic material, in particular from organic waste in a shaft furnace, which the waste travels through as a layer of bulk material under the action of gravity, where they are dried, degassed and with the addition of a flowing over a bed of embers Gasifying agents are gassed, that is to say the gasification agent above the ember bed depending on the ember bed temperature introduced and with gases developing in the bulk material layer in the direction of flow of the blood over the Glutbe @@ uncl (luz one for the discharge of the hat from the Ember bed provided discharge gap is performed, with the material above the gap is held until it is gassed. 2. The method according to claim 1, characterized in that the Fuel gas flowing out of the discharge gap in recuperative heat exchange for preheating serves to light the bulk material. 3. The method according to claim 1 or 2, characterized in that that the gasification agent is introduced into the bulk material layer in a zone, at which the material to be gasified has a temperature of about 2ovo0 C. 4. The method according to claim 1, 2 or 3, characterized in that the gasification agent before entering the bulk material layer as a coolant a discharge device flows through in the shaft furnace. 5. The method according to any one of the preceding claims, characterized in, that the bulk material layer in the case of gasification of fine-grained material is at least lo% by weight of coarse material is admitted. 6. The method according to any one of the preceding claims, characterized in, that the fuel gas flowing out of the bed of embers is discharged from the bed of embers Ash layer is led to the ash application. 7. Scllaciltofen for the continuous generation of fuel gas from organic Material, in particular from organic waste, with arranged at the head of the shaft furnace Material feed and a bulk material layer in the shaft, which is made up of organic material is traversed under the action of gravity, and with a device for Release of heat for drying and degassing the material in the bulk material layer and a connection for introducing gasification agent into one in the bulk material layer formed ember bed, characterized in that in the bulk material layer (5) A feed (11) for gasifying agent opens out above the ember bed (8) whose Flow rate from a regulator controlled as a function of the temperature in the bed of embers (17) is adjustable that the ember bed (8) from one on the ash discharge of the shaft furnace centrally arranged in the shaft, conical discharge device (7) supported is, which is cooled and rotatably mounted that at the lower edge of the discharge device a discharge gap (9) is provided with a gap width that depends on developing lumpiness of the goods in the ember bed is measured, and that at the ash discharge a generated fuel gas discharging fuel gas line (14) is connected. 8. Shaft furnace according to claim 7, characterized in that the fuel gas line (14) connected to a recuperative heat exchanger (6) which heats the bulk material layer is. 9. shaft furnace according to claim 7 or 8, characterized in that the feed (11) is connected to cooling lines for the discharge device (7). lo. Shaft furnace according to claim 9, characterized in that the feed (11) for the gasification agent passed through the discharge device (7) and opens centrally in the bulk material layer (5) in the shaft furnace (1). 11. Shaft furnace according to one of claims 7 to lo, characterized in that that at the bottom of the conical discharge device (7) an annular gap (9) is formed between the cone edge and the shaft furnace wall (10). 12. Shaft furnace according to one of claims 7 to 11, characterized in that that the conical discharge device (7) has a conical surface (18) with a Angle of inclination of 30 degrees, preferably with an angle of inclination (19) of 20 degrees having. 13. Shaft furnace according to one of claims 7 to 12, characterized in that that on the rotatable discharge device (7) on the ember bed (8) facing Conical surface (18) the gasified material in the ember bed to the discharge gap (9) conveying guide ribs (20) are attached. 14. ScilacluLofen according to Ci one of the Ans) rücfle 7 to 13, characterized in that that on the rotatable discharge device (7) reaching to the bottom of the shaft socket (1) Shovels (23) for discharging a forming at the bottom of the shaft furnace (1) Ash bed (22) are attached. 15. Shaft furnace according to one of claims 7 to 14, characterized in that that the bulk material layer (5) above the mouth of the feed (11) for the gasification agent has such a height that the flow resistance in the bulk material layer (5) above the mouth of the feed (11) for the gasification agent is greater than the flow resistance in the feed (11) for the gasification middle. 16. Shaft furnace according to one of claims 7 to 15, characterized in that that in the feed (11) for the gasification agent in operative connection with the Temperature in the ember bed t controlled flow controller (17) is used. 17. Shaft furnace according to one of claims 7 to 16, characterized in that that the discharge device (7) is arranged interchangeably in the shaft furnace (1).