DE19807988A1 - Removal of volatiles from solid fuels including all types of coal, and organic wastes - Google Patents

Abstract

The fuel is part-gasified in a reactor at 350 deg C-800 deg C under a pressure of 1-100 bar; producing coke, gas and steam. The fuel is preferably moved mechanically or pneumatically, mixing it into in a coking bed, cloud or conveyed stream at the operational temperature. Oxygen is added as air, air/steam mixture and/or as carbon dioxide, in quantities sufficient to maintain the operational temperature. Simultaneously, coke and gas/steam mixture are extracted from the reactor. Preferred Features: The temperature gradient in the gasification region is kept below 500 deg C by cyclic addition of oxygen over a large area, by the proportion of steam and carbon dioxide in oxygen or air supplied and by the intensity of mechanical and/or pneumatic mixing of the entrained fuel and coke. Before mixing-in the fuel, it is charged with liquid and/or gaseous wastes and/or pollutants.

Description

The invention relates to a method for separating volatile constituents from solid fuels such as all kinds of coal, renewable raw materials, especially wood, but also from garbage and other organic waste Constituents, such as these in municipalities, in trade and in industry Production.

The invention can be used for material-energy recovery of these fuels, for the disposal and recycling of garbage and waste Help of large central and small decentralized plants, but also for activation of coal, before its energetic recycling.

The prior art has an extremely large number of Methods and devices for material-energetic utilization of solid fossil and renewable raw materials and fuels as well as waste and Waste. A description and classification of the prior art processes Technology contains

• - Jüntgen "Coal gasification basics and technical application", Thiemig- Paperbacks - Volume 94, published by Karl Thiemig, Munich
• - M. Born and R. Berghoff, "Gasification process for the disposal of Waste ", Springer-VDI-Verlag GmbH, Dusseldorf 1998.

In Chapter 3 of the last-mentioned publication, the known processes are arranged and defined by B. Meyer according to process engineering features under the terms "degassing / pyrolysis / thermolysis", "gasification" and "combustion". According to this, the methods of the prior art are characterized as follows:

• - "Degassing / Pyrolysis / Thermolysis", separation of the volatile components with the exclusion of air at temperatures from 300 to 1,100 ° C and pressures of 1  up to 10 bar, by thermal decomposition of the fuels in coke, gas and Vapors, with the supply of process heat from the outside with the help of indirect Heat transfer or direct heat supply with the help of gaseous or solid heat carriers
• - "Gasification", thermal decomposition of the fuels in autothermal operation guidance by partial oxidation with part of the oxygen required for the complete combustion of the organic parts of the fuels required and / or other oxidizing gasifying agents, such as water vapor and carbon dioxide, in allothermal operation, in ash or slag, the can still contain carbon, gasification crude gas, which leads to fuel, city and Syngas can be processed and vapors, especially coal water materials, at temperatures from 800 to 1,600 ° C and pressures from 1 to 100 bar.
• - "combustion", complete conversion of the chemical enthalpy of the Fuels in physical enthalpy of the combustion gases complete oxidation of the organic components of the fuel with Oxygen mixtures, especially with air, at temperatures from 800 to 2,000 ° C and pressures from 1 to 20 bar.

In the prior art, the volatile constituents are eliminated the degassing, pyrolysis and thermolysis processes Available because of the supply of the necessary process heat from the outside have a high apperative effort.

The aim of the invention is to reduce the equipment required wandes in the separation of volatile constituents from solid fuels by thermally decomposing the fuels into coke, gas and vapors as they do in the prior art by "degassing / pyrolysis / thermolysis" process is achieved.  

The object of the invention, with the solution of which the object is achieved, is the supply of process heat required from the outside in the prior art to avoid.

In the course of our own experimental investigations, it was found that the fuels relevant to the invention with oxygen, in the form of air or in Mixture, preferably with steam and carbon dioxide at ambient and increased pressure is stable exothermic even at significantly lower temperatures react as required in the gasification process of the prior art. Building on this, the volatile inventory is proposed according to the invention parts of the fuels through partial gasification in the low temperature range from 350 to 800 ° C and under pressures of 1 to 100 bar in reactors and the Thermally decompose fuels in this way into coke, gas and vapors, whereby the fuels preferably in a mechanically or pneumatically moved Coke bed, a coke feed stream or a coke flight cloud are mixed in, which essentially consist of the coke of the fuel and so on a lot of oxygen, in the form of air and / or in a mixture with water vapor and / or Carbon dioxide is supplied that the temperature of the coke to the predetermined Area corresponds, on the one hand, with simultaneous separate removal of coke and gas / steam mixture on the other hand from the reactors.

According to the temperature gradients in the coke bed in the Flight cloud or set in the flow below 500 ° K, by large, if necessary cyclical entry of oxygen into the coke, through the proportion of water steam and carbon dioxide in oxygen or air and by the intensity of the mechanical and / or pneumatic mixing of the registered Fuel with the coke and the coke itself.

According to the invention, it is also the solid fuel, the garbage or the waste before partial gasification with liquid and / or gaseous waste and / or Loading pollutants.  

The economic and technical advantage of the invention is that avoiding the supply of process heat from the outside of the apparatus Effort for the separation of the volatile components from the fuels by thermal decomposition of the fuels into coke, gas and vapors drops almost 50%. This is an essential requirement for the further Implementation of new concepts for the material-energetic utilization of renewable raw materials and for the integration of more powerful coal gasification processes in combined cycle power plants and for waste recycling.  

The embodiment of the invention is described below with two examples become.

1st example

The technical task of this example is the separation of the volatile constituents from wood chips, which are to be used materially and energetically. The example is described with the aid of FIG. 1, which represents a suitable device for carrying out the method according to the invention.

The dry wood chips available for recycling are conveyed into the filling shaft 2 of a stationary cylindrical reactor 3 with a stuffing screw 1 , which seals the device from the environment in an airtight manner. In the reactor 3 there is a charcoal bed 4 at a temperature of 500 ° C., which fills approximately half of the cylinder volume of the reactor 3 and is circulated with turning elements 5 which are fastened on the shaft 6 . The setting of the turning elements 5 is such that the charcoal is partially transported in opposite directions. The shaft is moved at 1 to 30 revolutions per minute depending on the temperature profile in the charcoal bed 4 . At the same time, so much oxygen, in the example at 50 ° C water vapor-saturated air, is blown into the charcoal bed 4 via chambers 7 , which are formed by the reactor wall 8 and a gas-permeable sintered plate 9 , that the mean temperature of the charcoal bed is the predetermined reaction temperature of 500 ° C corresponds. The gas emerging from the charcoal bed, which contains the volatile constituents of the wood, including tar, is discharged from the reactor via the gas outlet 10 and the fully cooked charcoal via the height-adjustable weir 11 and the outlet nozzle 12 and for further use, e.g. B. supplied a gasification in which the tar-containing gas is burned medium in a first process stage to hot gasification, which reacts endothermic to tar-free fuel gas for gas turbines and engines in a second process stage with the charcoal.

2nd example

The technical task of this example is the separation of volatile components from fuel dust, which was made from gas flame coal. The task is solved according to the invention by mixing the fuel dust and 500 ° C hot fine coke, which was produced by the method according to the invention, via a pneumatic conveying device 1 and blown into a cyclone 2 with the aid of an air-water vapor mixture. The fuel dust and the fine coke react with the oxygen in the air and the water vapor in such a way that when the process is approximately isothermal at 500 ° C, the volatile constituents are expelled from the fuel dust and fine coke and dust and tar-containing gas are produced. The dust and tar-containing gas is via the outlet 3 , for. B. fed a high temperature gasification and gasified exothermic to 1,500 ° C hot gasifying agent, the tars being completely converted into gas. The fine coke from the cyclone flows into the collecting vessel 4 and from there via the lock 5 to the pneumatic conveying station 6 . Part of the hot fine coke is fed from the conveying station 6 to the conveying device 1 and thus driven in circles, while the excess portion of the fine coke is also removed pneumatically from the conveying station 6 and, for. B., a reactor is supplied by the gasification agent produced from the dust and tar-containing gas with the fine coke endothermic reaction to tar-free fuel gas, the z. B., can be used as a gas turbine fuel.

Claims (3)

1. A method for separating volatile constituents from solid fuels, such as all types of coal, waste and other organic waste by thermal decomposition of the fuels into their volatile constituents and coke, characterized in that the fuels in a partial gasification reactor at operating temperatures of 350 to 800 ° C and under pressures of 1 to 100 bar and thereby thermally broken down into coke, gas and vapors, preferably by mixing the fuels in a mechanically or pneumatically moved coke bed that is at operating temperature, a coke flight cloud or a coke feed stream, which essentially consist of the coke of the fuel and so much oxygen, in the form of air and / or in admixture with water vapor and / or carbon dioxide, that the temperature of the coke corresponds to the predetermined temperature range, with simultaneous separate removal of coke and gas -/There mpf mixture on the other hand from the reactor. 2. The method according to claim 1, characterized in that the temperature Gradients in the coke bed, the coke stream or the flight cloud below 500 ° K can be set by large, possibly cyclical addition of oxygen to coke, through the proportion of water vapor and carbon dioxide in oxygen or the air and by the intensity of the mechanical and / or pneumati mixing the registered fuel with the coke and Coke itself. 3. Process according to claims 1 and 2, characterized in that the Fuels before they are mixed with the coke with liquid and / or gaseous waste and / or pollutants loaded.