EP2719747B1

EP2719747B1 - Gasification method of coal-bearing raw materials, char and coal

Info

Publication number: EP2719747B1
Application number: EP13461551.7A
Authority: EP
Inventors: Piotr Sarre
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-10-12
Filing date: 2013-10-07
Publication date: 2018-11-28
Anticipated expiration: 2033-10-07
Also published as: EP2719747A1; PL224212B1; PL401192A1

Description

The object of the invention is the gasification method of coal-bearing raw materials, char and coal, as well as the arrangement of the equipment conducting for this process for industrial synthesis gas (syngas) production.
Various gasification methods of coal-bearing raw materials and coal leading to the production of gaseous fuels with a high hydrogen and carbon monoxide content are known, as are the devices and systems for the implementation of these methods. An example is Polish Patent No. 205483 , where the method involves waste gasification at a temperature of 150-350°C, with air inflow to the reactor at flow rate of 200-400 m³/hr and an increase of air flow to 400-680 m³/hr at the end of gasification process to incinerate the gasification residue at a temperature of 550-850°C, and the injection of steam into the reactor at a pressure of 0.1-0.2 MPa to produce generator gas.
Patent application No. PL.381200 presents the method of energy production through waste gasification in which the waste, for instance, municipal solid waste is dumped into a shaft melting gasifier, dried counter-currently, gasified with the simultaneous melting of solid waste, after which liquid waste is removed and dust-laden crude gas is discharged from above, the water is cleaned and cooled and finally taken through the separation and electrostatic distribution zone. Then, the resulting gas is fed into a burner, or generally taken to generate energy. The method is distinguished by the fact that hot raw gases discharged from the melting gasifier are taken to the hot gas and steam generator in which hot gas is mixed with steam and this mixture passes through a dual-rotor turbine driving the electrical generator, whereby the initial reaction takes place at the same time. The pre-cleaned mixture of hot gas and steam is fed into the precipitation device in which, using water supplemented with the reactive agent suspension and repeatedly using expansion and compression combined with foaming, this mixture is cooled and pre-cleaned whilst the fluid is collected.
The pre-cleaned gas is taken to the gas filter in which the gas foams with the reactive agent, the foam is removed and, finally, the cleaned gases are brought to further energetic use, for example, for combustion in an engine. The invention also encompasses a device for the production of energy from waste gasification.
Invention No. PL.161778 deals with the method and device for the gasification of solid fuels, especially fine-grained or dusty fuels, with the gasifying reactor equipped with gasifying burners, a device for separating volatile dust from crude gas, a volatile dust tank and a device for returning volatile dust to the gasifying reactor. The gasifying burners are equipped with a primary oxygen supply channel, which is coaxial with respect to the burner axis and which surrounds the annular fuel supply channel and an annular secondary oxygen supply channel which surrounds this channel. Volatile dust separated from raw gas is introduced into the axis of at least one stream of fuel/reactive medium, positioned with its assistance, in the primary reaction zone of the gasifying reactor and is melted in it. The ratio of the mass of primary to secondary oxygen ranges between 1:1 and 1:4, favourably between 1:1 and 1:3.
The method of gasification of carbon-based materials known from the description of patent PL.164016 is characterized by the fact that carbon-based material, in a form of a stationary bed filling the corona reactor is subjected to the action of non-equilibrium plasma at atmospheric pressure and room temperature, whereby plasma is generated by a pulsed corona discharge, while CO₂ flows through the carbon-based material cocurrently or counter-currently with respect to flowing electrolyte solution in the cooler. The device has a corona reactor filled with carbon-based material, containing an axially located corona electrode, while the outer part of the cooler is an external cylindrical electrode. The corona electrode is connected to a device supplying power.
The method of continuous gasification of liquid hydrocarbons from the low temperature carbonization process in the carbonization gas stream before their condensation, using the mixture of oxygen and steam, which is known from the description of patent No. PL.167505 , is characterized by the fact that the gasification process is conducted outside the low temperature carbonization device in the carbonization gas stream in a laminar flow occurring in the intergranular spaces of the packing in the counter-current shaft reactor. The volatile liquid hydrocarbons contained in this stream are subjected to the pyrolysis process and then these pyrolysis products are gasified in the hydrothermic gasification reaction zone situated upstream, under which a gasifying agent is introduced. The invention also includes the gasification reactor for liquid hydrocarbons.
The method of pyrolysis and gasification of organic matter or organic matter mixtures is known from the description of patent PL.194523 . Organic substances are introduced into the reactor for drying and pyrolysis, where they are brought into contact with fluidized bed material in the fluidized combustion bed or in which they come into contact with the material from the fluidized bed via the fluidized combustion bed reactor wall, resulting in drying and pyrolysis. The solid residue containing carbon, possibly with some steam, pyrolytic gases and fluidized bed material, are fed back to the fluidized combustion bed, in which the carbon residue of organic substances is ashed, the fluidized bed material is heated and re-introduced into the pyrolytic reactor. Steam from drying and pyrolytic gases are then treated with condensing substances in the reaction zone situated further, so that a gaseous product with a high calorific value is obtained. Drying and pyrolysis are conducted in at least one pyrolytic reactor. The fluidized combustion bed, in which the pyrolysis residue is incinerated, acts as a stationary fluidized bed. Pyrolytic gases are introduced into the intermediate heat exchanger. Waste gases from combustion, possibly containing material from the fluidized bed, are brought into contact with the intermediate heat exchanger, so that their heat is used in the reaction of the pyrolytic gases with the solidifying agent.
The method of pyrolysis and gasification of waste materials, particularly specific and/or hazardous waste materials, including the gasification and melting stage, the stage of processing of the mixture of gases obtained and the vitrification stage, is known from the description of patent No. PL.191219 . These stages include the following processes: processed material is gasified at a temperature of between 1300 and 1500°C in a period of between 3 and 15 seconds and melts in a period of between 5 and 30 minutes, in the total absence of air, yielding a mixture of combustible, non-combustible and inert gases in at least two, sequentially conducted stages of gasification. A constant temperature is maintained by applying at least one thermal lance in each of the gasification stages. The mixture of combustible and non-combustible gases obtained in such a way is cleaned and undergoes energy recovery treatment. Then, the inert gases or a part of the inorganic and mineral substances are obtained in a vitrified state. The reactor is divided into two sections:

one (or more) primary gasification chamber (chambers)
secondary gasification and melting chamber.

The primary gasification chamber consists of a vertical cylinder with an opening or outlet in the middle of the said cylinder cover for charging with waste. A place for introducing the thermal lance is always located in the upper part of the cylinder, but with a tangential clutch. The lower part of the cylinder is tapered like a truncated cone, so as to connect the cylinder with the pipe connecting it to the secondary gasification and melting chamber. The volume and length of the cylinder and pipeline specify the length of time in which waste remains in contact with the hot gases produced by the thermal lance and the surface of the fireproof coating which is kept at the anticipated operating temperature (1300-1500°C). The gas flow produced in the primary gasification chamber creates a descending flow, which tangentially enters the secondary gasification and melting chamber, together with waste introduced for gasification and melting.
Likewise, the secondary gasification and melting chamber consists of a vertical cylinder situated at a lower level with respect to the primary chamber. The lower part of this cylinder constitutes a base or basin for melting the mineral waste residue. The fireproof coating of the said base is oriented so as to obtain an inclination or slope of between 5 and 30%, with the best slope being 20%, between the highest point (gas inlet region from the previous chamber) and the lowest, diametrically opposite point (melted ash discharge region). The length and slope of this track set the duration and melting of the gasification residue, respectively. A second thermal lance is located on the cylinder wall of the secondary gasification and melting chamber, always near the base, having the task of maintaining the operating temperature in accordance with the set condition (1300-1500°C). Therefore, in addition to melting, gasification is conducted to the end and, since this happens in two successive stages, it features very high efficiency levels.
WO 2012/055012 A1 shows a reforming zone which is mostly homogeneous and a heterogeneous fluidized bed reaction zone. In the homogeneous reaction zone hydrocarbons (CH4, "residual gas") is mixed with oxygen. The stream does also contain gaseous tar and small amounts of char and is therefore not 100% homogeneous but nevertheless the characteristics of this stream are more in line with a homogeneous stream than that of a heterogeneous stream, as it presents a gaseous fuel / oxygen mixture with small particles entrained in the flow that do not alter the reactivity of said stream.
A number of other inventions regarding the gasification process, which are conducted using air, oxygen, steam or their mixtures, are also known. The most common processes are those conducted in counter-current shaft reactors or fluidized bed reactors, as well as using air gasifying burners. A fundamental issue of gasification is the minimization of the tar content in the final gas, the most complete possible carbon conversion and the least possible concentration of inert components in the gas. The existing methods either have a high concentration of tar in the gas or a high level of inert components in the gas produced.
The method of achieving the gasification of coal-bearing raw materials, char and coal involves conducting it in the co-current system using a favourably turbulent gas flow. The method according to the invention is implemented in a series of alternating homogeneous and heterogeneous reaction zones with a mixture of steam, hydrocarbon vapours and/or combustible gases, with the oxygen or oxygen with steam injection into the homogeneous reaction zone, which increases the temperature of the homogeneous zone to no higher than 1000°C, whereby fine-grained coal and coal-bearing raw material being the feed, best below 2 mm, is mechanically distributed throughout the heterogeneous reaction zone to ensure the continuous development of the contact surface dissipated in a form of solid-phase curtains with carbon dioxide and steam. The gas temperature between successive heterogeneous reaction zones is raised to no higher than 1000°C via an oxygen or oxygen with steam injection and adjusted for each homogeneous reaction zone. An amount of hydrocarbon and/or combustible gas vapours is added to the steam and oxygen mixture supplied to the first homogeneous reactor, which enables the temperature of all gases in this reactor to be raised to over at least 700°C, preferably up to 1000°C. At the transition from the homogeneous to the heterogeneous zone, the gas obtains a favourably progressive rotational motion. The solid-phase is dumped continuously from the shelves of the heterogeneous reactors, so that the dumping takes place from at least one shelf, but preferably from three shelves simultaneously. The layout of the devices containing co-current homogeneous and heterogeneous reactors is set up in a number of pairs of homogeneous and heterogeneous reactors starting with the homogeneous reactor, whereby the solid phase and gases are moved between heterogeneous reactors along separate paths. Such handling of the process enables the receipt of virtually tar-free synthesis gas, the expected conversion of carbon contained in the feed and the use of lower gasification temperatures, which decidedly restricts the carbon reduction of sulphates to sulphur dioxide and reduces the vapour pressure of any possible heavy metals.

Example 1:

5 kg/h of coal with 40% ash content originating from the municipal solid waste carbonization installation, of an average granularity of 1.1 mm, was introduced into the co-current multistage laboratory reactor set (fig. 3). The coal was pre-heated to a temperature of 450°C. Steam of an amount of 5.6 kg/h, mixed with 0.56 kg/h of propane, all at a temperature of 250°C, was simultaneously introduced into the cascade of reactors. Oxygen of 93% was added to the gas mixture before its introduction into the first stage of the reactor, raising its temperature to 1000°C. In the next homogeneous reactors of the cascade, the gas temperature was increased to 870°C via an oxygen injection. After the fifth heterogeneous reactor and the cooling of the gas to 30°C, approximately 9.4 Nm³/h of gas was obtained of the composition: CO₂ 16.9%, CO 40.6%, H₂ 35.5%, CH ₄ 2% and N₂ 5%, with 95% coal conversion.

Example 2:

5 kg/h of coal with 40% ash content originating from the municipal solid waste carbonization installation, of an average granularity of 1.1 mm, was introduced into the co-current multistage laboratory reactor set. The coal was pre-heated to a temperature of 450°C. 5.6 kg/h of steam, mixed with 0.56 kg/h of propane, all at a temperature of 250°C was simultaneously introduced into the cascade of reactors. Oxygen of 93% was added to the gas mixture before its introduction into the first stage of the reactor, raising its temperature to 1000°C. In subsequent homogeneous reactors of the cascade, the gas temperature was increased to 950°C via an oxygen injection. After the fourth heterogeneous reactor and the cooling of the gas to 30°C, approximately 10.3 Nm³/h of gas was obtained of the composition: CO₂ 11.7%, CO 42.8%, H₂ 39.5%, CH₄ 1% and N₂ 5%, with 97% coal conversion.
The external energy needed to cover the energy deficiency of the reaction between carbon and carbon dioxide, and steam with carbon, is supplied in doses by the physical heat of the gas emitted in the reaction of oxygen with the combustible components of the gas in volumes preceding gas contact with the solid phase containing elemental carbon. In this procedure, it is advantageous to initially introduce specific quantities of hydrocarbons and/or combustible gases into the steam fed to the gasification and to raise the temperature to the technologically set temperature via an oxygen injection. Such action is more effective than shell heating of steam. According to this principle, the array of devices in which gasification is conducted according to the invention, starts with the chamber which is the homogeneous reactor, in which gases for the gasification process are autothermally heated.
The example of implementation of the invention is presented in the diagram, where fig. 1 shows the schematic diagram of the gasification system, fig. 2 presents an example of the horizontal projection of the layout of the shelves for the gasification reactor section with four rows of shelves situated every 90°, fig. 3 shows the axonometric view of the arrangement of the shelves in the heterogeneous reactor, while fig. 4 presents coal with 40% ash content, taken from a municipal waste carbonization installation of an average granulation of 1.1 mm.
This is a typical co-current homogeneous reactor 1, in which oxygen is supplied by the multiple nozzle system, while the chamber design provides an advantageously progressive gas rotation when passing into heterogeneous reactor 2.
Next, advantageously rotating hot gas, heated in this way to a temperature of at least 970 K, is directed to the next reaction chamber, where it comes into contact and reacts with the solid phase. The heterogeneous system reaction chamber represents a rotational pipe device 3, favourably inclined in the direction of the movement of the solid phase and the gas, in which the intensity of contact of the phases is increased by the curtain-spreading of the fragmented solid phase in the system of shelves 4 attached helically to the reactor walls (figs. 2 and 3). It is important for the dumping of the solid phase from the shelves to be continuous and that it takes place from at least one shelf, preferably from three shelves simultaneously.
Reactions take place in the heterogeneous co-current reactor between carbon and carbon dioxide producing carbon monoxide and between steam with carbon producing carbon monoxide and hydrogen. These reactions run because of the physical heat taken from the gas, the temperature of which declines in the direction of the movement of the phases. The solid and the gas phases are separated at the end of the heterogeneous reactor. The gas is fed to the next chamber of the homogeneous reactor, where it is heated to the technologically set temperature via the injection of a subsequent portion of oxygen and it again receives an advantageously rotational progressive motion. The heated gas is fed to the next heterogeneous reactor, to which the solid phase from the previous heterogeneous reactor is added by different path to that of the gas, without coming into contact with oxygen. The sequence of successive gasification reactors, alternately between homogeneous and heterogeneous, ends with the heterogeneous reactor. The number of devices and their individual lengths are calculated as a function of the average temperature of the process that is planned for technological reasons and the required degree of carbon conversion of over 95%.

Claims

Method of gasification of char, coal and coal-bearing raw materials, involving conducting it in a co-current system with an advantageously turbulent gas flow, characteristic that it is implemented in a row of alternating homogeneous 1 and heterogeneous 2 reaction zones, with a mixture of steam, hydrocarbon vapours and/or combustible gases, with an oxygen or oxygen with steam injection into the homogeneous reaction zones, which increases the temperature in the homogeneous zone to no more than 1000°C, whereby fine-grained, preferably below 2 mm, coal or coal-bearing material as the feed, is distributed mechanically throughout the heterogeneous reaction zone to ensure the continuous development of the contact surface distributed in the form of curtains of solid phase with carbon dioxide and steam, while the gas temperature between successive heterogeneous reaction zones is raised to no more than 1000°C via the oxygen or oxygen with steam injection, adjusted for each homogeneous reaction zone.
Method according to claim 1, characteristic that an amount of hydrocarbon vapour and/or combustible gases is added to tye mixture of steam and oxygen supplied to the first homogeneous reactor, which enables the temperature of all gases to increase in this reactor to at least over 700°C, preferably up to 1000°C.
Method according to claim 1, characteristic that, at the transition from the homogeneous to the heterogeneous zone, the gas is given an advantageously rotational progressive motion.
Method according to claim 1, characteristic that the solid-phase is dumped continuously from the shelves of the heterogeneous reactors, so that the dumping takes place from at least one shelf 4, but preferably from three shelves simultaneously.