Field of the Invention

This invention relates to a process for heating and gasifying a carbonaceous fuel, wherein the granular or lumpy fuel is arranged in a shaft reactor as stationary fixed bed which rests on a bed of inert material which in turn is held by a gas- permeable tray, and wherein feed gases are introduced into the shaft reactor and exothermally converted to a process gas, wherein the process gas is heated and wherein the process gas flows through the reactor from top to bottom. Useful carbonaceous fuels above all include coals of different qualities, which also can be used in mixtures among each other. However, suitable biomass also can be considered as carbonaceous fuel.

The invention likewise relates to a plant for carrying out the process.

Prior art

Such processes and plants are known. These are gasification reactors for producing synthesis gases containing carbon oxide and hydrogen, but also pilot plants which serve to examine carbonaceous solid fuels, such as coal, for their suitability and their behaviors as feed material in a coal gasification process, such as for example the Fixed Bed Dry Bottom Process, as it is described in Ullmann's Encyclopedia of Industrial Chemistry, 6th Edition, Vol. 15, Gas Production. In operation of such pilot plants defined gas mixtures of 0 ₂ , CO, C0 ₂ , H ₂ 0, CH ₄ , H ₂ , N ₂ etc. are required, which at high temperature (typically 700 - 1800 °C) and also at high pressure (typically 1 - 100 bar, absolute) are passed into reaction spaces. The classical ways for providing such gas mixtures either are cold premixing and subsequent heating by means of a heating system or heating separately by means of a heating system depending on the type of gas and subsequent mixing of the gases. The high temperatures and pressures employed require very expensive and hence costly configurations of the heating systems used.

Description of the Invention

It therefore is the object of the invention to provide a process and a plant which is capable of producing process gas with a certain composition and with a certain temperature and a certain pressure with less technical expenditure and of passing this gas through a fixed bed of fuel.

This object was solved by a process according to the features of claim 1 and by a plant according to the features of claim 7. Preferred aspects of the invention are described in claims 2 to 6 and 8.

According to the invention, heating of the process gas is effected by using the partial oxidation process, which is described e.g. in Ullmann's Encyclopedia of Industrial Chemistry, 6th Edition, Vol. 15, Gas Production, Chapter 3.2. In this process, a gas consisting of hydrocarbons with known composition is mixed with oxygen and steam, ignited and converted to carbon oxide and hydrogen. This conversion is effected exothermally, so that the gases involved in the conversion reactions are heated. By adjusting the quantity ratios of the starting gases, a process gas with a certain composition and temperature is produced in this way. The quantity ratios are chosen such that the gas mixture obtained is ignitable and the partial oxidation can be effected. An advantageous aspect of the invention consists in that the feed gases are 0 ₂ , C0 ₂ , H ₂ 0, hydrocarbon, H ₂ and/or N ₂ . By using the partial oxidation process, a process gas can be produced with these gases, as it is required for testing coal by simulating the process conditions of a fixed-bed pressure gasification process.

Another advantageous aspect of the invention consists in that the feed gases are added at at least two different points along the longitudinal axis of the shaft reactor. The final adjustment of the composition and the temperature of the process gas is effected in that the residual gas quantities are added to the gas mixture heated by partial oxidation at a second point in the reactor.

Another advantageous aspect of the invention consists in that the first point of the addition of gas into the shaft reactor is located at the highest point of the reactor and the second point is located at a distance below the first one, which numerically corresponds to at least twice the diameter of the reactor, wherein the diameter of the reactor is 100 to 200 mm and wherein the diameter of the reactor is substantially constant over the entire height of the reactor. In this way, it is ensured that the gases added at the second point do not influence the partial oxidation.

Another advantageous aspect of the invention consists in that the inert material is granules of Al ₂ 0 ₃ . Such granules satisfy the process requirements with regard to permeability for the process gas stream, temperature resistance and costs. Another advantageous aspect of the invention consists in that the process gas is passed through a catalyst bed arranged above the fixed bed, before it flows through the fixed bed. In this way, the composition of the process gas is rendered more uniform, the chemical conversions taking place in the gas are accelerated, and hence the composition of the gas is brought closer to the theoretically calculated and intended composition, which corresponds to the thermodynamic equilibrium. The invention also comprises a shaft reactor for carrying out the process according to any of the preceding claims, comprising a reactor vessel, a gas- permeable tray arranged in the reactor vessel, a bed of inert material arranged on the gas-permeable tray, a fixed bed of granular or lumpy fuels arranged on the bed of inert material, inlets for introducing the feed gases, at least one region within the reactor vessel for exothermally converting the feed gases to the process gas, at least one outlet for discharging the process gas leaving the coal bed, wherein the inlets for introducing the feed gases are arranged at at least two different points along the longitudinal axis of the shaft reactor.

Another advantageous aspect of the invention consists in that the shaft reactor, at least in the region of the coal bed, is equipped with a jacket heater. In this way, heat losses via the reactor wall to the environment can be avoided.

Exemplary embodiment

Further features, advantages and possible applications of the invention can also be taken from the following description of the drawings and the exemplary embodiment. All features described and/or illustrated form the subject-matter of the invention per se or in any combination, independent of their inclusion in the claims or their back-reference.

The only

Fig. 1 schematically shows a reactor according to the invention for testing coal.

With reference to the drawing, Fig. 1 , the invention will now be explained in detail. A bed 2 of inert material, such as Al ₂ 0 ₃ , is held by a gas-permeable tray 3. On the bed 2 a further bed 4 is located, which consists of a coal to be tested with regard to its gasification properties and is meant to correspond to the fixed bed of an industrial-scale reactor. Into the head 1a of the reactor 1 , the gas streams 5, oxygen 6, steam 7, carbon dioxide 8, and hydrocarbon are charged, which are heated by partial oxidation. For igniting the partial oxidation, an ignition source not shown in Fig. 1 , e.g. an ignition flame, an electric igniter or an ignition catalyst are installed in the reactor head 1a.

To ensure the ignitability of the gas mixture produced in the reactor head 1a, a part of the gas quantities which are required for producing the gas composition desired for testing the coal can be charged into the reactor through gas inlets 6a, 7a and 8a, which are located below the combustion zone 1 b of the partial oxidation. The process gas 9 thus produced flows through the bed 4 of the coal and the bed 2 of the inert material and leaves the reactor 1 at the bottom as product gas 10. The beds are heated by direct heat exchange with the process gases.

In the region of the coal bed 4, the reactor is equipped with a heating jacket 11. The same allows to additionally supply energy to the reactor for heating beside heating by the process gas.

List of Reference Numerals

1 reactor

1 a reactor head

1 b combustion space of the partial oxidation

2 bed of inert material

3 gas-permeable tray

4 bed of coal

5 oxygen

6 steam

6a second introduction of steam

7 carbon dioxide

7a second introduction of carbon dioxide

8 hydrocarbon

8a second introduction of hydrocarbon

9 process gas

10 product gas

1 1 heating jacket

12 distance between the first and the second point of addition of the feed gases

13 diameter of the reactor