The present invention relates to a jet gasifϊer which is meant for gasifying fragmented solids of proper chemical composition, e.g. coal or, in particular, biomass, and the method of controlling its operation.

Gasification consists of two principal processes: the process of pyrolysis (degassing), which results in the transformation of the solid being gasified into pyrolitic gases and carbonization product; and the process of actual gasification where the coal in the carbonization product reacts with the volatile gasification agent, usually atmospheric oxygen or steam, which in the case of the former agent results in the production of carbon monoxide and in the case of the latter agent - carbon monoxide and hydrogen and in some conditions methane (when the pressure of the process is high) and, in all cases, to the production of solid mineral components from the carbonization product. What is also required for gasification of a selected substance is initiation heat, since the above-mentioned processes take place at temperatures in the range of several hundred degrees Celsius.

There are numerous types of gasifiers. Three of them are described below. The first type, which is the most traditional and is used for gasification wood, is one where the reaction chamber where pyrolysis and then the actual gasification take place and the biomass combustion chamber form one integral component. In such gasifiers, the heat required for the process is generated during the partial burning of the wood being gasified. The construction of such gasifiers is similar to regular grate furnaces, with the exception that air and possibly steam (when steam is the gasifying agent) is supplied to their enlarged combustion chamber through specially located connection ports. Such gasifiers also have proper outlet connection ports to remove the gas mix produced inside. Wood is put into such gasifiers from the top, often through a lock, so as to better control the quantity of air supplied into the reaction chamber. As wood moves gravitationally down the reaction chamber, it becomes hotter, it degasses and becomes partly gasified. A part of the wood, mostly in the form of carbonization product, falls down and reaches the actual combustion chamber and burns on a grate, thus providing heat for the upper layers of wood. The process can be controlled through regulation of the quantity of air and gasification agent supplied through the aforementioned connection ports. The combustible gas that is collected from the gasifier is very polluted and must be treated in a filtration and separation system. Moreover, the burned wood is transformed into ash which is collected underneath the grate.

The second type of existing gasifiers is one where the reaction chamber is closed and heat is supplied to the chamber using the membrane method, i.e. by heating up its walls, e.g. with gas burners supplied with some of the combustible gas produced in the gasification process.

The third type of gasifiers, which was invented fairly recently, is gasifiers for gasification of various substances which use a liquid metal reactor (LMR). The reactor consists of a ceramic container with melted metal inside. The temperature of the metal is maintained by induction currents or by gas burners. In such gasifiers, the reaction chamber is the space between the surface of the melted metal and the dome (usually a ceramic one) that covers the top of the container. The material to be gasified is fed into the reaction chamber from the top through a charging lock in the dome. Steam or sprayed water is fed into the chamber through a proper connection port. Another connection port is used for removing the gas mix produced in the chamber. The solid mineral components produced in the gasification process float on the surface of the melted metal and are removed from the container from time to time through a tapping point.

The construction of a gasifier which is the subject of this description is based on a new solution, which is different than the three described above, and which is described in the patent aplication no. P-385941 of 25 August 2008 titled "A jet gasifier and a method of controlling its operation." The difference between the gasifier described in the aforementioned application and the one presented herein consists in that in the first one the end products of gasification produced in the reaction chamber (namely the mix of hot gases and mineral particles) are collected from the chamber and are cooled by a water-driven jet pump and in the second one they are cooled in a cooler where cooling is performed, in particular, with water in the form of a water mist. Thus, the second solution uses much less water and the water does not need to be returned to be recirculated and cooled; consequently, this solution uses only a separation system, as opposed to a separation and cooling system. Some assumptions have been made in the description which follows and in drawings no. 1 - 5 which the description refers to. These assumptions must be taken into consideration in order to properly assess the information contained therein. The description is not a strictly technical description, which means that it does not include such elements as the location of pressure and temperature meters and sensors and the location of some valves, e.g. safety valves, which follows general engineering principles. Also, drawings no. 1-5 and the description do not mention valves that are typically an integral part of components used in the gasifier, such as a steam generator. Also, the description does not include the detailed construction of the separation system as there are numerous commercially available solutions for separating a mix of gases, water, and solid particles. The more detailed version of the separation system which is described is just one of the most simple versions possible.

Moreover, when analyzing drawings no. 1-5, one must assume that the proportions of dimensions of elements shown therein are not technically significant, but are of qualitative importance only. The drawings do not show a control system which is electrically connected with each of the components as this would make the drawing too intricate and would add any more value than the information concerning the control system that can be found in the description. For the same reason, the drawings do not show the thermal and electric insulation of the spiral steam superheater (SS) as well as the insulation of other components, i.e. the jet pump, the reaction chamber, and the hydraulic connections between the individual components of the gasifier. Moreover, in the description, the solid substance to be gasified is simply called "mass."

According to the present invention, the important characteristic of the construction of the jet gasifier (fig. 1) consists in that it includes among others the dry steam generator (SG) supplied from the outside, a steam superheater (SS), an injector jet pump (IJP), a system for feeding the ground mass to be gasified (MFS), a reaction chamber (RC), a cooler (CO) a separation system (SEP), a combustible gas container (CGC), valves, to include safety valves, and various meters and sensors, in particular temperature and pressure meters and sensors, and an electronic control system, and that these components are connected hydraulically is such a way that the steam outlet from the dry steam generator (SG) is connected, preferably through an electrically controlled pressure reducing valve (PRV), with the inlet of the steam superheater (SS), and its outlet is connected with the supply nozzle (nozzle propeller) of the injector jet pump (IJP), and its inlet port is connected through an electronically-controlled stop valve (SV) with the ground mass outlet in its feeding system (MFS), while the outlet port of the injector jet pump (IJP) is connected, preferably with a flange packing (P), with the inlet of the reaction chamber (RC), which has the shape, preferably, of a spiral coil, in particular of a vertical cylinder, as shown on drawings no. 1-5, whose upper opening constitutes the chamber's inlet and the lower opening - its outlet, and the outlet of the chamber (RC) is connected, preferably with a flange packing (P), with the inlet of the cooler (CO), and the outlet of the cooler (CO) is connected with the inlet port of the separation system (SEP), while the outlet of the purified cooled mix of combustible gases from the system (SEP) is connected through a check valve (CV) with the combustible gas container (CGC), and the electronically controlled valves located in the aforementioned components and the electronic meters and sensors, in particular pressure and temperature meters and sensors, are electrically connected with the electronic control system, and, moreover, the hydraulic connections between the individual components of the gasifier and the reaction chamber (RC), and the housing of the jet pump (IJP) are lined with a layer of thermal insulation, and the components that are exposed to high temperatures are made from high-tempreature creep resistant materials, preferably from superalloys, and, moreover that the sections of the components through which flows the stream of steam and gases produced in the process are correlated with the working pressure of the steam generator (SG) and with the working pressure of the check valve (CV) that they assure a jet-type gasification process, i.e. a continuous process.

Another important characteristic of the construction of the jet gasifier (fig. 2) consists in that its steam superheater (SS) consists of a heater (H) which is a pipe, preferably spiral-shaped, made from a high-temperature creep resistant material that conducts electricity, preferably a superalloy, and one end opening of the pipe is hydraulically connected with the steam outlet of the dry steam generator (SG) while the other is hydraulically connected with the supply nozzle (nozzle propeller) of the injector jet pump (IJP), and these connections, preferably flange-type, comprise a sealing and insulating part (SI) which insulates both connected components electrically; moreover, an electric current source (ECS) is connected to the end parts of the aforementioned pipe and is controlled by the gasifiers's control system and the whole heater pipe is thermally and electrically insulated on the outside, and, moreover, the pipe has temperature and pressure meters and safety valves which are also electrically connected to the electronic control system, while a properly selected superalloy of which the heater (H) pipe is made allows for heating up the steam coming from the generator (SG) and flowing through the steam superheater (SS) to a temperature ts, in particular higher than 1000 ⁰ C.

Another important characteristic of the construction of the jet gasifϊer (fig 2) consists in that the heater (H) pipe in the steam superheater (SS) is divided into several electrically-insulated sections, of which each is supplied with electric power separately, in particular with currents of different intensity.

Another important characteristic of the construction of the jet gasifier (fig. 2) consists in that the heater (H) pipe in the steam superheater (SS) has different wall thicknesses in different sections which leads to different quantities of heat being emitted in the different sections.

Another important characteristic of the construction of the jet gasifier (fig. 3) consists in that its feeding system (MFS), i.e. the system for feeding ground mass to be gasified, consists of a funnel-shaped ground mass container (MC), preferably with a vibrator, and the bottom round-shaped opening of the funnel is located exactly over the inlet of the chamber of a screw driven by an electric motor (EM) and is hydraulically connected with this inlet, while the outlet of the screw chamber is located exactly over the inlet port of the injector jet pipe (IJP) and is hydraulically connected with the port through an electrically-controlled stop valve (SV), and the rotating screw collects through the open valve (SV) the ground mass from the container (MC) and moves it towards the suction port of the injector jet pipe (IJP) through which, and through the suction nozzle of the injector jet pipe (IJP), it is sucked in by a stream of steam from the supply nozzle (nozzle propeller) of the injector jet pipe (IJP), whereas the operation of the stop valve (SV) and the operation and rotation of the motor (EM) are controlled by the electronic control system of the gasifier.

Another important characteristic of the construction of the jet gasifier (fig. 4) constists in that its cooler (CO) is made from a metal pipe (MP), preferably in the shape of a spiral, in whose walls are installed valves (SNV) supplied from the outside with water with nozzles that spray water inside the pipe in the form of water mist.

Another important characteristic of the construction of the jet gasifier (fig. 5) consists in that its separation system (SEP) consists of a cyclone (C), a set of dedusting filters (SDF), preferably bag filters, and a container (CON) for waste mixture of water and mineral particles, and that these elements are hydraulically connected with each other and with the remaining part of the gasifier in such a way that the outlet of the cooled and moisturized mix of gases and mineral particles from the cooler (CO) is connected, preferably using a collar packing (P) with the inlet of the cyclone (C), and the outlet of the mix of gases, free from water and mineral particles, from the cyclone is connected with the set of dedusting filters (SDF), preferably bag filters, and the outlet of the dedusted mix of gases from the set of dedusting filters is connected through a check valve (CV) with the combustible gas container (CGC), and the part of the cyclone (C) where the mix of water and mineral particles collects is connected through a drain valve (DV) with a container (CON).

Another important characteristic of the construction of the jet gasifier (fig. 5) consists in that its separation system (SEP) comprises a gas mix dryer.

Another important characteristic of the construction of the jet gasifier (fig. 5) consists in that its separation system (SEP) comprises a module for washing carbon dioxide out of the mix of gases.

Another important characteristic of the construction of the jet gasifier (fig. 5) consists in that its separation system (SEP) comprises a module for removing from the mix of gases such unwanted gases as, in particular, chloride, hydrogen sulfide, or sulfur dioxide.

Another important characteristic of the construction of the jet gasifier (fig. 6) consists in that an injector jet pump (IJP) consists of an inlet pipe (IP) with a constant cross-section, where one end is hydraulically connected with the steam outlet of the steam superheater (SS) and the other end - with the inlet of the reaction chamber (RC), and that the middle section of the pipe (IP) is hydraulically connected with the end of the pipe (P _MFS ) whose other end is hydraulically connected with the outlet of the mass feeding system (MFS), and that the pipes (IP and P _MFS ) are thermally insulated.

Another important characteristic of the construction of the jet gasifier (fig. 7) consists in that a reaction chamber (RC) consists of the proper reaction chamber (PRC) in the shape of a pipe made from a heat resistant or, preferably, high temperature creep- resistant material, which also conducts electricity and has a high heat conductivity, in particular a superalloy, and that the ends of the pipe are connected, through a proper switch, with a power source (PS), and that the chamber (PRC) has thermal and electrical insulation (I) on the outside and that these components, namely the chamber (PRC) and its insulation (I) are set in the body (B), in particular a metal one, which assures that they are rigid and their construction remains stable.

According to the present invention, the important characteristic of the control method of the jet gasifier (drawing No. 1-5) consists in that the dry steam generator (SG) produces from externally-supplied water a stream of dry steam with the temperature tsσ and pressure P _SG and that the stream is directed, preferably through a pressure reducing valve (PRV), to the steam superheater (SS) where the steam is heated up to selected high temperature tss, and from the superheater (SS), the stream of steam is lead to the supply nozzle (nozzle propeller) of the injector jet pump (IJP) where the speed of the stream is increased and its pressure is decreased below the pressure level in the mass feeding system (MFS), which is generally below 1 bar, which allows for sucking the ground mass with the stream through the inlet port of the injection jet pump (IJP) and through the open stop valve (SV) from the mass feeding system (MFS) and then for directing the stream of steam mixed with the sucked-in mass to the injector jet pipe (IJP) diffuser where the speed of the stream is decreased and its pressure is increased (but not to exceed the original value of P _SG ), and from the diffuser the stream of steam mixed with the sucked-in ground mass is directed to the reaction chamber (RC) while simultaneously starting to rapidly heat up the ground mass using the heat of the surrounding steam, which leads to a drop of the temperature of the steam and an increase of the temperature of the ground mass and, as the stream of stream with the ground mass moves through the chamber (RC), the pyrolysis process (degassing of the ground mass) starts and quickly reaches the temperature of an exothermic phase from which moment the deeper layers of the particles of the mass are heated up by the heat emitted in the process of the exothermic reactions initiated in the outer layers and the process is continued in increasingly high temperature, preferably above 800 ⁰ C, and the actual gasification process begins, which consists in a reaction between the coal contained in the carbonization product, i.e. the solid product of pyrolysis of the ground mass, and the steam, which produces mostly carbon monoxide and hydrogen, and the carbonization product is transformed into mineral substances, and as a result of these processes, from the outlet of the chamber (RC) a mix of hot gases, including a residual amount of steam and mineral substance particles, is supplied to the cooler (CO), where the mix is rapidly cooled off, preferably with water mist sprayed continuously through the nozzles of the valves (SNV), and once the mix is cooled, it is supplied to the separation system (SEP) where, using one of the known methods, water and particles of mineral substances are separated from it, as well as various unwanted gases and chemical substances, and the resulting mix of combustible gases is fed through a check valve (CV) to the combustible gas container (CGC), whereas the pressure difference in the pipelines which forces a jet nature of the process is obtained by correlating the flow cross-sections of the gasifier components with the pressure of the steam generated in the steam generator (SG), namely psc and the working pressure of the check valve (CV), and eventually it is regulated by the pressure reducing valve (PRV).

Advantages of the jet gasifier according to the said invention.

The jet gasifier has all the advantages of the jet gasifier described in the aforementioned patent application no. P-385941, as well as the following:

- The gasification products are cooled even faster because the water mist used for cooling absorbs heat faster than a "solid jet" of water in the jet pump, which lowers even more the possibility for producing complex carbon, hydrogen, and oxygen compounds in the course of cooling.

- Cooling of gasification product is performed with much less water, which leads to the fact that it is not necessary to separate particles of mineral substances from it and return it for recirculation and, instead water and the particles may be immediately mixed with gravel and build aggregate or blocks by adding cement.

Example of application

An example of application for a jet gasifier is a gasifier for gasification of straw. The general construction of the gasifier is shown on drawings no. 1. Additionally it consists of a steam superheater (SS) shown on drawing no. 2, a straw feeding system (MFS) shown of drawing no. 2, a cooler (CO) shown on drawing no. 4, and a separation system (SEP) shown on drawing no. 5. The dry steam generator (SG) is a standard dry steam generator where the heat needed for evaporation of water comes from combustion of wood or biomass briquettes. The generator produces slightly superheated dry steam with temperature ts _G > 100 ⁰ C, but not exceeding 200 ⁰ C, and pressure in the range of several bars. The spiral heater (H) pipe of the superheater (SS) is made from a high- temperature creep INCONEL superalloy which is suitable for use in temperatures up to 1200 ⁰ C. The ends of the pipe are connected to a low- voltage power source. The current flows through the pipe, which in turn heats up the steam flowing through it to the temperature tss in the range of 900-1000 ⁰ C. As indicated in the description, the spiral- shaped heater of the superheater is thermally and electrically insulated on the outside. Moreover, the sealing and insulating elements (SI) in flange connections insulate the heater (H) electrically from the steam generator (SG) and the injector jet pump (IJP). The stream of superheated steam coming from the superheater (SS) moves to the supply nozzle of the injector jet pump (IJP) where the pressure of the steam is lowered below one bar and the flow rate of the steam increases. This allows for the stream of steam to suck in the ground straw from the mass feeding system (MFS) through the inlet port of the injection jet pump (IJP) and through the open stop valve (SV). The injector jet pump (IJP) is also made from INCONEL superalloy. The straw feeding system (MFS) consists of a charging hopper closed on the top into which ground straw is fed from the top by a screw conveyor. The charging hopper is equipped with a vibrator which causes the straw to move down in a uniform fashion towards a round narrow outlet leading to the screw chamber. It should be noted that the finer the ground straw is, the less air is in the bottom part of the charging hopper and the less air is fed with the straw to the inlet port of the injector jet pump (IJP). The screw located in the chamber connected to the round outlet of the charging hopper is driven by an electric motor (EM) whose operation and rotational speed is controlled by the control system of the gasifier. By changing the rotational speed of the screw, one can increase or decrease the amount of straw fed into the injector jet pump (IJP). Between the inlet port of the injector jet pump (IJP) and the outlet of the screw chamber in the straw feeding system (MFS) there is a stop valve (SV) which is closed when the operation of the gasifier is completed or when, for some reason, the level of straw in the charging hopper drops below a permitted level. This eliminates the possibility of the injector jet pump (IJP) sucking in air only. The ground straw that is sucked-in by the inlet port of the injector jet pump (IJP) is mixed in the pump with a stream of hot steam and starts to heat up and travels, along with the stream of steam, to the diffuser of the injector jet pump where the pressure of the stream of steam increases above one bar, but does not exceed the original level. From the diffuser, the stream of steam mixed with straw particles flows to the reaction chamber (RC). The shape of the chamber resembles that of the spiral heater (H) in the superheater (SS) and the chamber is made from the same superalloy as the heater and is also thermally insulated on the outside. The length of the chamber (RC) depends on the estimated time of the processes of pyrolysis and gasification, at the assumed size of the stream of steam and the amount of straw fed to the chamber. This is why a spiral shape of the reaction chamber (RC) is better than a vertical cylindrical shape, as the former allows it to be significantly longer. In the front part of the reaction chamber the temperature of steam drops while the temperature of straw particles increases as straw heats up by absorbing the energy of the surrounding steam, but in the further part of the chamber this process is reversed. After the straw particles reach the temperature between 300 and 400 ⁰ C, the pyrolysis processes in them go into the exothermic phase, which means that heat is emitted, which raises the temperature of the partly degassed particles and heats up the gases surrounding the particles. As a result, the temperature of the process in the further part of the reaction chamber rises and proper gasification can take place in a temperature exceeding 800 ⁰ C. This high temperature eliminates ring hydrocarbons and other complex compounds of carbon, hydrogen, and oxygen, thus assuring high efficiency of the gasification process. Generally speaking, proper gasification consists in effecting a reaction of the product of carbonization of straw in the process of pyrolysis, or degassing, with steam. The carbonization process consists mostly of coal and small amounts of mineral compounds. The coal combines with steam to produce carbon monoxide and hydrogen. Thus, straw is gasified to produce small amounts of solid mineral substances. The stream of the mix of gasification products, which besides gases contains the aforementioned particles of mineral substances, is fed to the cooler (CO). In the cooler, the stream gets into the water mist and is instantaneously cooled, which limits the possibility that complex compounds of carbon, hydrogen, and oxygen form during the cooling process. From the cooler, the stream of the gasification products is fed into the separation system, namely the cyclone, where the mix of water and particles of mineral substances is separated. From the cyclone, the mix of gases flows to the set of dedusting filters (SDF), which are bag filters, which stop the dust that has not bee separated in the cyclone. After the gas is dedusted, it is beneficial to dry it up so as to eliminate any remaining steam from it. Such a purified mix of gases should contain only hydrogen, carbon monoxide, some carbon dioxide and a small amount of nitrogen (which sucked in with the ground straw). The mix, as a final product of gasification, is sent through a check valve (CV) to the combustible gas container (CGC). It must be remembered that in the course of gasification in the lower part of the cyclone (C) a mix of water and particles of mineral substances collects at all times. Some of the mix (never all of it) is drained from time to time through a drain valve (DV) into a container (CON). Since only a part of the mix is drained, gases in the cyclone cannot get out of the cyclone during draining. It must be remembered that for the above-mentioned process to be continuous, there must be a proper pressure difference in the system which forces the movement of first the stream of steam, then the stream of steam with particles of straw, and finally the moist mix of gasification products. This pressure difference is achieved by adequately correlating the working pressure of the steam generator (SG) and the working pressure of the check valve (CV), as well as the flow cross-sections of the different components of the gasifier; eventually, the pressure difference is adjusted with a pressure regulating valve (PRV).

The mix of combustible gases in the container (CGC) can be used as fuel for a gas power generator.