Field of Technology

Gasification Technical Problem

Technical problem to be solved by present invention is possibility of separation of synthesis gas and flue gases in two separate chambers of thermal treatment system of fuel on slanted grate.

State of the Art

The process of burning solid fuel, particularly biomass and waste comprises of the following phases, namely: heating, drying, pyrolysis, gasification and complete combustion. Fuel on arrival in the chamber starts to warm and dry, then begins the process of decomposition (pyrolysis), gasification and combustion.

In the process of gasification it is desirable to produce synthesis gas with the highest or sufficiently high energy value in order to utilize the gas.

Known solutions are built so that the fuel is gasified and burned in single chamber. In this chamber the synthesis gas is mixed with the flue gases of combustion as it reduces the energy value. Another variant is that the flue gases are kept in vertical gasification chamber. Disadvantages of these processes are:

Separate gasification chamber

- Poor mixing of fuel at a fixed grate

- Poor adjustment of fuel type

- A lot of unburned particles

Description of New Invention

Device and method for gasification of solid fuel, in particular coal solves above described technical problem using movable grate (1) positioned inside a chamber. Under said grate (1) air is controllably injected into one or more zones (2). Above the grate (1) there is a combustion chamber split into two or more parts (3.1 and 3.2) with a partition (1 1) made of fireproof lining. The position of said partition (1 1) may change according to type of fuel. Into those two parts of the chamber the air may be injected in one or more zones (4). The fuel is additionally warmed up and gasified by passing hot flue gases through the fuel, or by injection of steam (5). In such a way no additional oxygen is introduced into the fuel so synthetic fuel of higher energy value is produced.

This process features separate gasification and combustion on same moving grate (1) which runs through both parts of combustion chamber, part for gasification and part for combustion. The grate can also be manufactured as a cascade (6). In such a way two- or multi stage grate can be produced separated by a cascade enabling more intensive mixing of the fuel resulting in higher decomposition and faster combustion of larger fuel particles.

Fuel inlet (7) is positioned higher allowing larger amount of fuel into the first part of the chamber (3.1) thus generating larger amounts of synthesis gas. The device is designed to allow exit of synthetics gas through the exhaust outlet (8) and further use of it or mixing with other final incineration flue gases in the final combustion chamber (10). Into the final combustion chamber the air (oxygen) is blown (9), which simultaneously swirls flue gases and provides good mixing for complete combustion. Advantages:

Gasification in moving grate using air or 02

Gasification in moving grate with steam injection

- Extraction and use of synthesis gas

Separate exit of synthesis gas - higher energy value of gas

- Better control of the combustion / gasification

Lower NOx levels due to low temperatures

One or more zones to blow air under the grate.

- Above the grate there are two separate chambers - separate gasification and

combustion in moving grate

One or more zones to blow the air above the grate

Potential use of single- or multistage moving grate

- The possibility of blowing recirculated flue gas

In addition to already described there are more embodiments:

- intensive gasification by leading hot gases through the fuel (Figure 2)

- synthesis gas is lead separately to the gas devices, flue gases are lead into the boiler (Figure 1)

- allowing a combination of both systems (Figure 3)

Below the invention is described using figures whereas the figures form part of this patent application and represent:

Figure 1 presents the system in which the synthesis gas is lead separately to the gas devices, flue gases are lead into the boiler, showing: moving grate (1), air injection (2), part of chamber for production of synthesis gas (3.1), part of chamber for combustion (3.2), zones for air injection (4), steam (5), opening for fuel (7), opening for exit of synthesis gas(8), chamber partition (11), opening for exit of flue gases (12).

Figure 2 presents the system in which the hot gases are used for intensive gasification, showing moving grate (1), air injection (2), part of chamber for production of synthesis gas (3.1), part of chamber for combustion (3.2), zones for air injection (4), steam (5), opening for fuel (7), opening for exit of synthesis gas(8), chamber partition (1 1).

Figure 3 presents the combination for production of synthesis gas and combustion, showing: moving grate (1), air injection (2), part of chamber for production of synthesis gas (3.1), part of chamber for combustion (3.2), zones for air injection (4), steam (5), cascade (6), opening for fuel (7), opening for exit of synthesis gas(8), opening for injection of air or oxygen (9), final combustion chamber (10), chamber partition (1 1), opening for exit of flue gases (12), the synthesis gas valve (13), flue gas valve (14), valve for entry into final combustion chamber (10).

In all three embodiments there is a single combustion chamber separated into gasification part and/or production of synthesis gas (3.1) and part for combustion (3.2) with chamber partition (11).

In first embodiment (fig.l) the fuel is entering through the opening for fuel (7) and migrates along the moving grate (1) first through part of the chamber for production of synthesis gas (3.1) and then through part of the chamber for combustion (3.2). Into the chamber the air (2) is injected under moving grate (1) and then optionally steam (5) or air (4) in additional zones is injected. The synthetic gas exits from the moving grate (1) through opening for exit of synthesis gas (8) while the hot flue gases exit from the moving grate (1) through opening for exit of flue gases (12).

In the second embodiment (fig. 2) the fuel is entering through the opening for fuel (7) and migrates along the moving grate (1) first through part of the chamber for production of synthesis gas (3.1) and then through part of the chamber for combustion (3.2). Into the chamber the air (2) is injected under moving grate (1) and then optionally steam (5) or air (4) in additional zones is injected. The hot flue gases travel in the opposite direction to the moving grate (1) toward part of the chamber for production of synthesis gas (3.1). Through this process the gasification becomes more intensive. The mixture of synthesis gas and flue gases are then lead through the opening for exit of synthetic gas in further processing. In the third embodiment (fig. 3) the fuel is entering through the opening for fuel (7) and migrates along the moving grate (1) first through part of the chamber for production of synthesis gas (3.1) and then through part of the chamber for combustion (3.2). Into the chamber the air (2) is injected under moving grate (1) and then optionally steam (5) or air (4) in additional zones is injected. The moving grate (1) has additional cascade (6) enabling further mixing of fuel for better efficiency and better control of both processes - there can be also plurality of cascades. By using the valves one can choose between different processes. At open valve for flue gas (14) and open valve of opening for exit of synthesis gas (8) one arrives at the first embodiment. At closed valve for flue gas (14) and open valve of opening for exit of synthesis gas (8) one arrives at the second embodiment. At close valve for flue gas (14) and close valve of opening for exit of synthesis gas (13) and open valve for entry into the final combustion chamber (15) one arrives at the second embodiment upgraded with final combustion chamber (10). In this chamber air or oxygen through openings (9) are injected, and temperature of flue gases increased.