DE3123356A1 - Process and apparatus for taking off liquid slag - Google Patents

Abstract

The invention relates to a process and an apparatus for taking off liquid slag in the gasification of fuels in the form of dust or pieces. The object of the invention is the gasification of fuels in the form of dust or pieces with oxygen or a gasifying agent containing free oxygen in a reactor such that an undisturbed slag run-off is provided, if required together with the hot crude gas, in a cooling and granulation part of the slag outlet orifice at the lower end of the reaction space for the course of the gasification reactions at temperatures above the melting point of the ash/slag. According to the invention, the slag outlet orifice is provided with a heated moulded brick made of electrically conducting material and the moulded brick is heated by means of energy supplied by an induction coil.

Description

Title of the invention

Method and device for the extraction of liquid slag of the invention The invention relates to a method and a device for triggering liquid slag, around which with certain technologies of the gasification of dusty or lumpy fuels with oxygen or air in the liquid state To be able to safely discharge slag from the process.

Such gasification processes are used in the production of heating gases, Synthesis gases, reducing gas or town gas or

Mixed components of town gas.

Characteristic of the known technical solutions In the technology of the Gas generation is the gasification of dusty or lumpy fuels with a Mixture of oxygen and water vapor or air as a flame reaction in the flight cloud or known in the fixed bed. In the gasification of pulverulent fuels and in modern ones Process of gasification of lump fuels, the implementation takes place in such Temperatures that the mineral constituents of coal as molten slag attack. Especially when the gasification takes place under increased pressure the difficult technical task of designing the gasification reactor in such a way that that the slag flow is controlled and the slag is safely discharged from the system can be. Technical solutions are customary in which they are still inside the reactor the molten slag is granulated in water and cooled and is discharged from the pressure system as granules suspended in water. For the The operational reliability of such reactors is the design of the liquid slag outlet from the hot part of the reactor, the reaction space in the narrower sense, into the cooling and granulating part are decisive.

In the GDR exclusion patent 119 266 is a reactor for gasification described by coal dust under pressure, the reaction space of which consists of a water-loaded, The pipe wall construction is protected by a layer of refractory rammed earth.

There is one for the discharge of the liquid slag into the granulating part central opening provided in the bottom of the reaction chamber, the contours of which by the appropriately designed pipe wall construction with rammed earth coating will. The bottom of the reaction space is in the direction of the slag discharge opening weakly inclined. The opening is provided with a sharp slag drip edge.

It is a basically similar solution for a little above the Atmospheric pressure running gasification plant known where the upper edge of the central Schlackeab run opening is elevated like a dam, so that the slag on the ground of the reaction space is controlled and overflows over the dam (Ullmann's Encyclogadie der technical chemistry, 3rd edition, volume 10, page 416, 1958). It is further known liquid slag and hot gas together via a bottom opening with a drip edge to be transferred to a cooling room, see e.g. B. Meunier, Gasification of Solid Fuels ..., Weinheim / Bergstrasse, 1962, page 453.

Finally, DT-OS 2 325 204 describes a reactor for gasification of coal dust under pressure, where hot gas and liquid slag share be withdrawn downwards through a central opening in the bottom of the reaction chamber, a slag bath at the bottom of the reaction space through a dam around the central opening is maintained.

Operating experience in such systems shows a high level of susceptibility against the solidification of slag in the outlet opening depending on certain technological conditions, especially during start-up and shutdown, resulting in malfunctions and hazards. Therefore an attempt was made through special employment z. B. the pulverized coal burner or by additional gas-operated heating burners to overheat the slag strongly in the vicinity of the drain. The consequences are increased Gasification agent requirement, high additional fuel requirement and thus a worsened one Gasification efficiency as well as heavy wear of the reactor lining in the lower area.

When using gas burners are extensive, complicated technological Equipments necessary to purify, compress-and-clean part of the production gas to be fed back to the reactor.

Object of the Invention 4 The object of the invention is a method and a Device for safe and continuous operation of gasification plants of fuels with liquid cinder vent to develop clogging through To avoid slag additions and to ensure a steady drainage of slag. In order to operational reliability and availability are increased. At the same time the wear should be the liner and burner are lowered.

Statement of the essence of the invention The object of the invention is Gasification of dusty or lumpy fuels with oxygen or a free one Oxygen-containing gasification agent in a reactor such that at the bottom End of the reaction space for the gasification reaction to take place at temperatures Above the melting point of the ash / slag, an undisturbed slag drainage, if necessary together with the hot raw gas in a cooling and granulating part of the slag discharge opening is guaranteed.

According to the invention the object is achieved in that the The reaction chamber is closed off at the bottom and is preferably centrally arranged in the form of a ring Slag drainage opening with a heatable form stiff from electrically conductive material is provided. Mixtures are used as electrically conductive material made of carbon, ceramic materials, SiC, Si3N4, SiON2 and others. in varying proportions used.

By means of a suitable energy supply by means of an induction coil the shaped stone is heated, for which the following technical solution was chosen: After Figure 1, a device is arranged in the lower part of a gasification reactor, the one made of a form stiffness representing the slag drainage opening, one in insulating concrete embedded water-cooled induction coil and a metallic water box, on the inner surface of which shielding plates made of copper are applied.

Surprisingly, it has been found that to ensure a continuous Slag discharge a certain ratio between the supplied electrical Energy and the sensible energy (heat) of the escaping production gas and the slack must be guaranteed. This ratio is in the range of 1:10 up to 1: 200, preferably between 1: 100 to 1: 200, with relationships to the chemico-physical Properties of the slag exist. If this ratio is not reached, then comes it solidifies and thus overgrows until the slag drainage opening is clogged; if the ratio is exceeded, the slag film runs off too quickly, it can overheating and thermal destruction of the shaped stone.

It was also found that to ensure a continuous Slag drainage is only suitable for a limited frequency range of the induction current which is between 500 and 10,000 Hz, preferably between 2,400 and 8,000 Hz. It turned out that in the proposed frequency range the electrically conductive, liquid slag layer is also inductively heated.

Another arrangement according to Figure 2, which the principle of integration the necessary equipment for inductive heating of the slag outlet opening shows a gasification reactor consists of a slag outlet opening, one these surrounding Induction coil, a implementation of the electrical Feed into the pressure chamber, a battery of capacitors, the medium frequency generator and the two pressure measuring points.

The circuit arrangement according to FIG. 3 shows the two Pressure measuring points, two shut-off valves, the differential pressure transmitter, the power supply, the control amplifier and the excitation winding. Those shown in Figures 1, 2 and 3 Devices take effect during the operation of the reactor as follows: In the work area of the reactor enters through the outlet opening and thus through the formite Mixture of produced gas and liquid slag. The shaped stone made from electric conductive material is present, during operation of the reactor by the induction coil, which, together with the capacitor group, forms the load circuit for the medium frequency generator forms, warms. The electrical connection of the water-cooled induction coil Copper is carried out through the electrical feed through to the pressure chamber into the pressurized reactor.

With the help of the two pressure receivers, the differential pressure transmitter a value is determined that controls an amplifier, its output signal accordingly the level of the existing differential pressure, the excitation of the medium frequency generator influenced.

The control mechanism of the variant shown in Figure 3 works in such a way that when the differential pressure at the transmitter increases, thus reducing the cross-section in the shaped brick of the slag outlet opening due to the growth of slag parts is signaled, the excitation for the medium frequency generator is increased and thus the shaped block is supplied with more energy via the induction coil. This takes place a temperature increase in the shaped brick, the slag that has been attached begins to melt and the cross-section for the exit of gas and Schlabke is enlarged again. As a result of the reduction in cross-section at the transmitter Differential pressure becomes the excitation for the medium frequency generator weakened and thus the energy input into the form rigidity is reduced.

The invention will be explained using the following exemplary embodiment: In one Test facility for gasifying pulverulent fuels turns coal dust into a Amount of 80 - 120 kg / h corresponding to an amount of energy of 1.6. 106 - 2.4. 106 kJ / h introduced into the reaction chamber of a reactor via appropriate burners.

A cooling tube shield is used to provide thermal protection for the pressure-bearing envelope with applied ramming mass. At the bottom of the reactor there is a slag drainage opening, through the liquid slag and gasification gas via an electrically heated shaped block 2 get into the cooling and granulating section. Gas and slag are after exit from the slag drain hole through injected it is quenched water, which emerges the slag settles in the water bath and is drawn off through an opening. The gas is discharged via a raw gas outlet nozzle. The amount of raw gas produced is 300 m3 per hour, that with a temperature of 1,400 - 1,700 OC over the shaped stone 2 leaves the reaction chamber. The sensible energy (heat) of the raw gas lies between 6.7. 105 - 7.2. 105 kJ / h. To secure the slag drainage, an electrical Line for heating the shaped stone from 1 - 25 KW corresponding to an amount of energy from 3.6. 103 - 90. 103 kJ / h installed, the ratio between electrical Energy and the sensible energy (heat) of the gas produced in the test operation was to achieve favorable, continuous operating conditions at 1: 100 to 1: 200. It was possible through a differential pressure-controlled regulation similar to figure 3 to supply the electrical energy irregularly or periodically due to the process. It turned out that according to the test conditions, the frequency of the electric current had to be set to 8,000 Hz.

List of the reference symbols used 1 - slag discharge opening 2 - molded brick 3 - insulating concrete 4 - water-cooled induction coil 5 - metallic Water tank 6 - shielding plate 7 - gasification reactor 8 - implementation of the electrical Feed into the pressure chamber 9 - capacitor bank 10 - medium frequency generator 11 - pressure measuring point 12 - pressure measuring point 13 - shut-off valve 14 - shut-off valve 15 - Differential pressure transmitter 16 - Power supply 17 - Control amplifier 18 - Excitation winding

Claims (6)

Invention claims 1. A method for gasifying dusty or Lumpy fuels under pressure, preferably under pressures between 5 and 50 bar by partial oxidation with oxygen or with a containing free oxygen Gasification agents at gasification temperatures above the melting point of the fuel ash are, preferably 50 - 200 OC and liquid slag discharge with subsequent Cooling and granulation, with the slag discharge alone or together with the hot gasification gas can take place, characterized in that the at the bottom of the Reaction chamber arranged slag discharge opening through an electrical, medium-frequency Electricity is inductively heated, the ratio between the supplied electrical Energy and the sensible energy (heat) of production gas and slag between 1:10 to 1: 200, preferably 1: 100 to 1: 200. 2. The method according to item 1, characterized in that the frequency of the induction current between 500 and 10,000 Hz, preferably between 2,400 and 8,000 Hz. 3. The method according to items 1 and 2, characterized in that the frequency of the induction current is chosen so that the electrically conductive slag layer is also inductively heated. 4. The method according to item 1 to 3, characterized in that the heating of the shaped block is made time-limited or periodically. 5. The method according to item 1 to 4, characterized in that at the same time Exit of slag and production gas of the slag deposit in the slag discharge opening through a differential pressure measurement with measuring points before and after the slag outlet is measured and the ratio of the supply of electrical energy and the sensible energy (heat) of the production gas is regulated so that the slag content melts. 6. Device for carrying out the method according to points 1 to 5, characterized in that the downwardly closing off the reaction space, preferably centrally arranged ring-shaped slag drainage opening (1) with a heated shaped block (2) is made of electrically conductive material and the device part for energy input from a water-cooled induction coil embedded in insulating concrete (3) (4) with metallic water tank (5) attached to the shielding plates (6) made of copper are, exists.