Method and system for producing syngas from combustible materials - Patents.com

Abstract

A method for producing gas from a combustible material is provided. The method includes the steps of filling the combustible material into a containment structure and sealing it within the containment structure. An oxidizer is supplied to the sealed containment structure at a controlled flow rate and rate of controlled movement such that the combustible material is partially converted, thereby leaving a thermally affected layer of the combustible material after an injection point has passed the material. At least a portion of the combustible material is converted to molten slag and / or char that accumulates as a bottom thermally affected layer and subsequently cools and solidifies. The method is characterized in that it further includes the steps of draining the solid slag and / or char in the bottom thermally affected layer from the lower material remaining in the containment structure to remove the solid slag and / or char from the containment structure.

Description

[Technical field]

[0001] This document claims priority to Australian Provisional Application No. 2022900268, filed February 9, 2022, the entire contents of which are incorporated herein by reference.

[0002] FIELD OF THEINVENTION The present invention relates to a method for producing gas from combustible materials such as biomass and solid waste, and in particular, an apparatus and method for batch gasification of combustible materials is disclosed. [Background technology]

[0003] Gasification is a process in which gas is produced from a carbonaceous feedstock by partial oxidation. The product gas is typically called "syngas" or "syngas" and can be used as a feedstock for a variety of applications including power generation, hydrogen production, synthetic fuels production and chemicals production. It is well known that gasification occurs in a reducing atmosphere at high temperatures, typically in the range of about 700-1500 degrees Celsius.

[0004] The main challenges of biomass and waste gasification include high capital and operating costs, operational difficulties caused by variable feedstock characteristics and high tar levels in the syngas. Due to the small volume and distributed nature of biomass and waste sources, most biomass and waste gasifiers have small capacity (in the range of a few to tens of MWt) compared to coal or petroleum coke gasifiers (in the range of hundreds to thousands of MWt), resulting in poor economies of scale. Biomass and waste, especially when obtained from waste sources, can be highly variable in moisture content, energy content, density, size and shape. The variable characteristics of biomass and waste can reduce the performance and availability of the gasifier.

[0005] Almost all solid combustible materials contain components that are inert in the combustion process; these components are called inorganic, and more commonly, ash, because these components form ash when the material is burned in a conventional fire. Solid ash is formed at temperatures below the ash fusion temperature. At much higher temperatures, the ash can melt, forming a slag that can be melted (if kept hot enough) or, more commonly, cooled and solidified into an inert rock.

[0006] Gasifiers are commercially available and come in a wide range of types, including updraft, downdraft, crossdraft, fluidized bed, entrained flow and plasma. Peak temperatures range from about 700 degrees Celsius to well over 1500 degrees Celsius depending on the design. Each of the different types of gasifiers has different characteristics with respect to cost, capacity, efficiency, gas quality, load following capability and feedstock compatibility. In particular, almost all existing gasifier designs utilize large vertical reaction vessels, require a steady supply of treated feedstock to the gasifier to maintain constant gas production, and require the continuous removal of inert material in the feedstock in the form of solid ash or molten slag. -

[0007] Updraft gasifiers that process biomass generally use a rotating grate and a screw or auger to continuously remove waste ash as a dry solid. An example can be found in EP 2589870. A drawback of this technology is that the ash must be prevented from melting and forming agglomerates or slag that plug the grate and auger. Slag formation is a common problem, especially in the gasification of feedstocks that produce ash with low fusion temperatures. Slag formation can cause blockages and damage the ash removal system. This can only be achieved by processing feedstocks that have a relatively high ash fusion temperature, and by ensuring that the peak temperature in the reaction zone is kept very low by using a moderator in the oxidizer. Unfortunately, these requirements preclude the use of most solid waste feedstocks, such as municipal solid waste (MSW).

[0008] High temperature gasifiers exist for treating residual wastes such as municipal solid waste, and have peak temperatures of about 1200-1600 degrees Celsius. However, these gasifiers generally contain a separate hearth or vitrification reactor where the ash is heated above its melting temperature to form a molten bath of slag in a separate zone or reactor, which is removed as a very hot molten liquid. Temperatures in excess of 1500 degrees Celsius are required to keep the slag in a molten state. U.S. Patent No. 9,074,152 (Nielsen et al.) describes a gasifier with slag melting in the bottom zone of the reactor and a plasma torch in the upper zone to maintain syngas temperatures of 1200-1500 degrees Celsius. The disadvantages of this design are that very expensive and thick refractory and insulating layers are required to contain the molten slag, and additional energy in the form of combustion or plasma generation or electrical heating is required to maintain the temperature and keep the slag in a molten state. High temperature gasifiers are therefore prohibitively expensive, and the refractories are prone to failure. As a result, they are not economical for treating biomass and municipal waste in most countries and generally only find a viable niche market in treating hazardous or medical waste.

[0009] Another by-product formed during gasification is char, a solid material formed during the initial stages of heating and pyrolysis of carbonaceous materials at temperatures of about 400-700 degrees Celsius. Depending on the gasifier design, char conversion to syngas can occur at low or high temperatures, but few gasifier designs achieve complete (i.e., 100%) char conversion in one go. Removing slag, ash and or char from the gasification process can be difficult.

[0010] An additional challenge in gasifier design is that gasifiers are operated by limiting the oxygen required for complete combustion, primarily to produce low calorific or low Btu (British Thermal Unit) gas. Thus, the gasifier should be sealable when in use. The openings of the gasifier, including the feed system, need to be sealable, openable, and resealable. Maintaining a hermetically sealable structure during feeding and removal of solid waste is important to allow the gasifier to operate continuously or be reusable for several cycles. This requirement is challenging due to the high operating temperatures and the need to simultaneously process feedstock and ashes of various shapes and sizes, with the potential for significant wear and tear. Complex feeding systems using lock hoppers or screw feeders are commonly used to charge new feedstock, but they are prone to leaks, wear and seizure.

[0011] Most continuous ash removal systems use a rotatable grate to collect and discharge solid ash, and / or a water bath to maintain a gas seal and cool the ash before discharge. WO 2006061738 (Stadler et al.) describes a grate system for removing ash from a fixed-bed coal gasifier. EP 1687391 (Schilder) shows one example of a spray ring for wetting the char and / or slag in a water bath. Such systems can be very complex, subject to wear and corrosion, generate wastewater, and are susceptible to steam explosions.

[0012] The difficulty of reliably sealing the gasification reactor vessel during operation means that most biomass and waste gasifier designs operate near atmospheric pressure. Although some pressurized gasifier designs exist, they are generally limited to processing homogenous solids in the form of pulverized coal or biomass, delivered to the reactor vessel as a uniform particle suspension in an injection fluid, or mixed with water to form a pumpable slurry.

[0013] Biomass and waste feedstocks often contain high moisture content, which reduces gasification efficiency and produces wastewater after the syngas is cooled. Pre-drying of the feedstock is often performed using a separate drying unit, such as a rotary kiln dryer, prior to gasification. However, this requires additional handling of the feedstock, increasing costs and reducing process reliability.

[0014] Thus, there is a need for improved methods and systems for producing syngas from carbonaceous and combustible materials, particularly for mixed waste feedstocks and feedstocks containing relatively large amounts of inerts and contaminants.The present invention aims to ameliorate the problems of methods known in the art, or at least to provide a useful alternative. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] European Patent Application Publication No. 2589870 [Patent Document 2] U.S. Patent No. 9,074,152 [Patent Document 3] International Publication No. 2006061738 [Patent Document 4] European Patent No. 1687391 Summary of the Invention

[0016] In a first aspect, there is provided a method for producing gas from a combustible material, comprising the steps of: (a) filling a containment structure with a combustible material; (b) substantially sealing the containment structure; (c) supplying an oxidizer into the sealed containment structure via an oxidizer injection point to ignite the combustible material; (d) moving the oxidant injection point from one end of the containment structure to the other; (e) controlling the flow rate of the oxidizer and the rate of movement of the oxidizer injection point such that the combustible material is partially converted, thereby leaving a thermally affected layer of combustible material within the sealed containment structure after the injection point has passed through the material; (f) cooling and purging the sealed containment structure; (g) opening the sealed containment structure and filling with new combustible material above the top thermally affected layer remaining after completion of steps (c) through (e); Including, In the method wherein during step (e) at least a portion of the combustible material is converted to molten slag and / or char which accumulates as a lowermost thermally affected layer and subsequently cools and solidifies, the method further comprising the steps of: draining the solid slag and / or char in the lowermost thermally affected layer from the lower material remaining in the containment structure to remove the solid slag and / or char from the containment structure; (h) repeating steps (a) to (g); A method is provided, further comprising:

[0017] In conventional processes, the entire containment structure must be emptied at the end of a gasification cycle to remove the ash and / or slag. The containment structure is then recharged with fresh combustible material for a new gasification cycle. In the present invention, the ash in the form of slag is removed from the bottom thermally affected layer while remaining within the containment structure.

[0018] A surprising result discovered when operating the moving injection concept of step (e) was that inorganic (ash) material in the feedstock could be melted by the intense localized high temperature reaction zone and form slag. As the gasification zone moved away from the molten slag, it cooled and solidified to form a brittle mass. This observation, together with the present disclosure of a method to discharge slag and char at the end of the gasification cycle where the contents are cooled in a mechanical solids removal system, results in a unique gasifier design not previously known. A key feature of this design is that with the moving injection concept, biomass and waste materials can be processed at a high enough temperature to melt the ash into slag and form this non-hazardous material as in other high temperature gasifiers, but with the advantage that the slag can be easily removed at ambient temperature, avoiding the myriad complications and thermal inefficiencies of discharging slag when in molten form.

[0019] In an embodiment, the present invention provides a gasifier that operates to allow ash in the waste to form a molten solid, which is a slag, that is left in the reactor to cool and is discharged as a dry, cooled solid.

[0020] In one embodiment, the step of evacuating the slag in the lowermost thermally affected layer is performed by at least one ram.

[0021] In one embodiment, the present invention provides a gasifier that operates to allow the feedstock to be partially converted to char (which necessarily also contains ash from the feedstock) without forming slag. The solid char is discharged by at least one ram into the lowermost thermally affected bed.

[0022] In one embodiment, the present invention provides a gasifier that operates to allow ash in the feedstock to form slag and a portion of the feedstock to be partially converted to char. The solid slag and char are discharged by at least one ram into a lowermost thermally affected bed.

[0023] In a second aspect, a method for producing syngas from a combustible material comprises the steps of: filling a containment structure with a combustible material, the containment structure having a first side and a second side disposed along either side of an elongated axis; substantially sealing the containment structure; Optionally, heating the combustible material with a heating gas to pre-dry the combustible material; providing an oxidizer to the sealed containment structure; igniting a combustible material in the presence of an oxidizer; moving one or more oxidant injection points for injecting oxidant from one end to the other along an elongated axis of the containment structure, thereby partially converting the combustible material to syngas and leaving a series of thermally affected layers containing residual combustible material, char and slag; stopping oxidant injection and purging the containment structure with a purge gas; circulating a cooling gas through the cooling loop to cool the contents of the containment structure; removing one or more of the thermally affected layers containing residual combustible material, char and slag from other thermally affected layers below remaining within the containment structure using at least one ram operable to eject the residual combustible material, char and slag from the containment structure by moving from a first side of the containment structure toward an openable / closable opening in a second side of the containment structure; A method is provided, comprising:

[0024] Statements made with respect to the first aspect are applicable to statements made with respect to the second aspect, and vice versa, unless the context clearly indicates otherwise.

[0025] The present disclosure generally relates to gasification of combustible materials. By "combustible material" it is meant any material, or any combination of materials, capable of producing gas. The combustible material may be a carbonaceous material. In suitable embodiments, the combustible material may include a biomass material. The biomass material may be derived from a renewable energy source, such as, but not limited to, plant-derived or animal-derived materials. Non-limiting examples of plant-derived biomass materials include grasses (such as, but not limited to, sugarcane, switchgrass, and miscanthus), tree species (such as, but not limited to, Cyprus, oil palm, eucalyptus, blue gum, poplar, willow, and pine), hemp, grains such as wheat, legumes such as sorghum, corn husks, pongamia, wood pellets, lumber and timber waste, and horticultural waste. The plant-derived biomass material may be derived from an agricultural source. The plant-derived biomass material may include paper and cardboard. Plant-derived biomass materials can include fruits and vegetables.

[0026] Non-limiting examples of animal-derived biomass materials include sewage sludge and biosolids from wastewater treatment plants, and manure from animals of all kinds, including cows, sheep, pigs, chickens, and the like.

[0027] The combustible materials may include, but are not limited to, fossil fuels, such as coal, or combustible materials derived from fossil fuels, such as plastics. It is contemplated that the combustible materials may include or be derived from municipal waste, which may include combinations of combustible materials, such as, but not limited to, biomass and plastic materials. In exemplary embodiments contemplated combustible materials including combinations of multiple combustible materials, each combustible material may be in approximately equal proportions, or the proportion of one combustible material may exceed the proportion of another combustible material.

[0028] The combustible material may include food waste, agricultural waste, food waste, construction and demolition waste, municipal solid waste (MSW), biosolids, or mixtures thereof. By way of example only, the combustible material may be derived from municipal waste, which may include approximately 70% by weight biomass material, with some of the remainder being plastic material. The combustible material may include unprocessed, irregular, and / or oversized material. The combustible material may include at least 80% biomass material and 20% ash.

[0029] For all aspects, the terms "gas", "syngas" and "synthetic gas" are used interchangeably to refer to the gas produced according to the methods of the present disclosure. The gas produced from the gasification process is therefore particularly suitable for use in the generation of power and electricity. In embodiments, the produced syngas can be cleaned using conventional techniques and directed to a flare, combusted in an engine to produce electricity, or further processed to produce high purity hydrogen. This process results in the production of syngas, the formation of a thermally affected layer in the combustible material, and the formation of slag, ash and char. The ash can be fully or partially converted to slag.

[0030] The containment structure, sometimes referred to as a gasifier or reactor, is suitably configured to receive combustible material for the gasification process. The containment structure may be in the form of a receptacle, chamber, cell, pit or vessel. The containment structure according to any one of the disclosed methods or systems may be rectangular in shape when viewed from above, although other shapes are contemplated. In one embodiment, the containment structure has a horizontal axis that is longer than either the width or height of the containment structure.

[0031] Each containment structure may be constructed of carbon steel. The table below shows the indicated dimensions and production capacities of three possible reactor embodiments: a pilot reactor, a containerized reactor, and a large stick-built reactor. Reactor volumes may vary significantly, starting from just a few cubic meters to thousands of cubic meters. Similarly, syngas production flows may vary from tens of cubic meters per hour (Nm3 / hr) to tens and possibly hundreds of thousands of Nm3 / hr. [Table 1]

[0032] The walls can be insulated with many types of common insulating materials and lined with steel or refractory. The lining can be low alumina firebrick and calcium silicate insulation board. This design allows the sidewalls to self-insulate using primarily the feedstock, thereby limiting sidewall temperatures and preventing slag formation and overheating. The bulk of the containment structure is expected to experience temperatures of approximately 100-200 degrees Celsius, but the gasification front is expected to reach approximately 1500 degrees Celsius when operating with pure oxygen as the oxidizer. At a commercial scale, the containment structure can be constructed using modules based on standard shipping container dimensions. In one embodiment, the containment structure is constructed from two or more 40-foot tall cube containers stacked vertically.

[0033] The containment structures can be used to gasify a variety of waste feedstocks into synthetic gas (syngas). The design capacity of each gasifier can vary anywhere from 0.5 tonnes per day (tpd) to 1000 tpd of feedstock. If the process is scaled up, up to 500 or 1000 (or more) tons of waste per day could be processed.

[0034] To fill the containment structure, the lid is opened and the flammable material is filled manually or using any suitable type of mobile or stationary material handling plant. Suitable means for filling include, but are not limited to, excavators, material handlers, front-end loaders, cranes, telehandlers, forklifts, conveyors or rails. The flammable material can be handled directly or using bins. Optionally, the containment structure is purged with air prior to filling.

[0035] Once the combustible material is loaded into the containment structure, the lid can be closed and sealed. The seal is important because the gasifier operates by limiting the oxygen needed for complete combustion, so it is important that oxygen from the outside air cannot enter the containment structure during the gasification process. The seal can be any means that allows for an internal pressure of up to about 1, 2 or 3 kPag. The seal can be a liquid seal. The liquid seal provides a liquid barrier between the interior of the containment structure and the surrounding atmosphere. During operation, the reactor operates near atmospheric pressure. The reactor lid can be closed into a water seal trough located inside the containment structure that can provide an airtight seal. The liquid seal prevents gas from escaping the structure or air from entering the structure.

[0036] In one embodiment, after the containment structure is sealed and before gasification is initiated, there may be a step of heating the combustible material with a heated gas to remove moisture from the combustible material. Heating the combustible material with a heated gas to pre-dry the combustible material is optional. However, in a preferred embodiment, the method includes the step of heating the combustible material with a heated gas to pre-dry the combustible material.

[0037] The heating step may be performed with air if the presence of air at the heating temperature does not pose a risk of initiating combustion or smoldering reactions in the feedstock. If there is a risk, an inert heating gas such as nitrogen or carbon dioxide may be used. Nitrogen is selected by default as it can be easily produced by a nitrogen generator. Prior to heating, in one embodiment, the air in the containment structure may be purged to atmosphere via a safety vent using an inert gas such as nitrogen.

[0038] The combustible material feedstock can then be dried in situ using heated gas in a closed loop circuit. The heated gas may be delivered at a temperature in the range of about 75 degrees Celsius to about 150 degrees Celsius. In this circuit, the heated gas can be heated and then passed through a bed of combustible material feedstock. In a preferred embodiment, the heated gas is injected into the bottom of the containment structure and removed from the top above the level of the feedstock. In one embodiment, the heated gas is injected on the way up to the containment structure, while in another embodiment, the heated gas is injected from one side of the containment structure and collected on the other side of the containment structure. The moisture-laden gas exiting the reactor can be cooled to condense the moisture picked up from the feedstock while passing through the containment structure. With the moisture removed, the gas can be reheated and recirculated using heaters and blowers.

[0039] If the combustible material loaded into the containment structure has a low moisture content, drying may not be required. The low moisture content material may be refuse-derived fuel (RDF). The RDF may be roughly about half paper-based material and about half plastic material with a heating value of about 30 MJ / kg (i.e., intermediate between biomass at 20 MJ / kg and plastic at 40 MJ / kg).

[0040] MSW, on the other hand, generally has a moisture content of 25-30% by weight due to the presence of food waste with high moisture content, and MSW is typically contained within plastic bags. An advantage of the disclosed closed-loop drying system is that it can serve a dual purpose: heating the plastic bags to a high enough temperature that they soften and open to expose the contents, and thereby allow for effective drying of the entire contents of the MSW feedstock. This dual function relies on the use of an inert heating gas at a sufficiently high temperature, about 150 degrees Celsius or higher. Thus, the incorporated closed-loop drying system eliminates the need for several pre-processing steps that are usually performed by dedicated equipment, such as opening plastic bags, shredding the feedstock, and drying the feedstock.

[0041] Before starting the gasification step, the reactor must be purged of oxygen using an inert gas such as nitrogen or carbon dioxide. If the heating step was done with air, a separate purge step is required. If the heating step was done with nitrogen or carbon dioxide, the reactor is already purged of oxygen. The oxygen level in the reactor is checked by measuring the composition of the purge gas leaving the reactor or the composition of the recycle gas.

[0042] The oxidant delivered to the containment structure during the gasification process may be fed into the sealed containment structure by one or more injectors or lances, each injector configured to include a plurality of oxidant outlets each positioned to carry a flow of oxidant.

[0043] The oxidant injection members may be positioned along at least a portion of the base of the containment structure. Alternatively, the oxidant injection members are inserted into a bed of combustible material within the containment structure. In one embodiment, the oxidant injection members are solid retracting pipes or lances that inject oxidant from an end, optionally at a location along the pipe. The pipe or lance may be retracted through the containment structure during gasification operations to provide a moving heat front.

[0044] In larger containment structures, multiple injection members or lances may be used simultaneously. The lances may be arranged in a vertically and horizontally spaced pattern to evenly spread the oxidant outlets to cover most of the cross-sectional area of ​​the bed formed by the feedstock. In large containment structures, there may be from 1 to 50 lances.

[0045] Prior to start-up of the gasification operation, the lance or lances are typically placed in a "fully retracted" position, with the oxidant outlet nozzle located at the far end away from the syngas outlet pipe. This is the position where the gasification operation was stopped in the previous batch cycle. Prior to the start-up procedure, the lance is moved to a "fully inserted" position. The lance is forced into the reactor using a hydraulic ram, roller or rack-and-pinion system located outside and at one end of the reactor. In the fully inserted position, the lance tip, where the oxidant outlet nozzle is located, is close to the syngas outlet pipe, but far enough away from the syngas outlet pipe to ensure that there is enough feedstock between the lance tip and the outlet pipe for the start-up procedure.

[0046] The lance is preferably located in the bottom third of the reactor and after several batch cycles of operation the feedstock has been thermally affected to form small, highly permeable char particles. Therefore, forcing the lance into the fully inserted position using a hydraulic ram or other methods is not difficult and is very reliable.

[0047] During normal operation, the lance is retracted by a hydraulic ram or other suitable method at prescribed time intervals, which may be fixed or may be varied by the process control system based on the oxidant injection rate and other factors.

[0048] In principle, when multiple lances are utilized, they may be retracted independently or as a group. In a preferred embodiment, the lances are retracted as a group to limit the complexity of the mechanism used to push and pull the lances. In another preferred embodiment, the lances are formed into several groups and the lances of each group are retracted together using a single retraction mechanism.

[0049] In one embodiment, the oxidant for gasification is primarily pure oxygen supplied from an air separation unit. The design can allow for oxidant mixtures of air, enriched air or steam with oxygen, air or enriched air. The oxidant composition and flow rate can be controlled via flow injection valves. The reactor operates in a batch process, so there are several different stages in its operation.

[0050] In one embodiment, the method further includes controlling the flow rate of the oxidizer and the rate of movement of the oxidizer injection point such that the combustible material is partially converted, thereby leaving an unconverted, thermally affected layer of the combustible material within the sealed containment structure after the injection point has passed through the material. This moving oxidizer injection concept is the subject of Applicant's previous publication, WO2017205943, filed on June 5, 2017, entitled "PRODUCTION OF A GAS AND METHODS THEREFOR," the contents of which are incorporated herein by reference in their entirety. Any conflict between the disclosure of WO2017205943 and this disclosure should be resolved by returning to this document as the controlling document.

[0051] Following gasification, it is desirable to cool the contents of the feedstock within the containment structure so that the feedstock does not spontaneously ignite upon contact with air (during the removal step). It is also desirable to purge all syngas from the containment structure to ensure that as many of these components are recovered as products as possible and to prevent (or reduce) direct release to the atmosphere that would occur if the purge step were not performed. An inert gas, such as nitrogen or carbon dioxide, can be used to cool and purge the contents of the containment structure.

[0052] The cooling and purging steps are carried out in one reactor, but the resulting gas, a partially diluted syngas, can now be operated as a gasifier and mixed with product gas from a parallel reactor producing a steady stream of syngas.

[0053] The rate of injection of the inert gas during the cooling and purging steps can be controlled so that the inert content (nitrogen or carbon dioxide concentration) of the syngas resulting from the mixing of the two reactors is below a limit typically set by the specifications required by downstream users of the syngas. For example, when using gas engines, the downstream syngas shall meet a minimum heating value. For example, in the case of the production of hydrogen by separation from syngas in a pressure swing adsorption unit, there is a maximum nitrogen content above which the purity requirements of the hydrogen cannot be met by the pressure swing adsorption (PSA) unit.

[0054] The cooling and purging steps were carried out under the following conditions in the bed: Syngas component concentrations less than 1%, and A bed temperature below the autoignition or smoldering temperature of the feedstock when exposed to air The objective of the present invention may be to achieve the following:

[0055] The cooling and purging step can use the same equipment as the heating step, where no heaters are used, but rather a chiller is used to cool the resulting dilute gas to a low temperature near or below ambient temperature. In one embodiment, the cooling step can be accomplished by recycling the cold syngas to the containment structure, and then an inert gas can be used to purge the syngas from the containment structure.

[0056] After the inert gas cooling and purging steps are complete, an air purge can be initiated in preparation for venting the reactor to the atmosphere.

[0057] During gasification, the combustible materials are subjected to high temperatures which (in addition to forming gas) result in melting of the ash to form slag, and the slag agglomerates and solidifies within the thermally affected layer.

[0058] The solid agglomerates formed may include one or more of ash, slag, and char. Typically, slag forms agglomerates and large particles, and char forms fine particles. The solid material may include slag pieces having dimensions on the order of 1, 5, 15, 30, 50, 80 cm or more. The slag in the containment structure melts and separates during processing and after gasification, forming a bottom layer in the containment structure. As it cools, the slag tends to form brittle agglomerates, while the char is a fine powder. The slag agglomerates tend to crumble easily just by handling them and during their removal from the reactor.

[0059] After removing the slag-containing layer, the solidified slag can be separated from the residual combustible material and / or char or biochar. Since the agglomerated slag pieces are much larger than the other particles, separation can be performed by a sorting device. The residual combustible material and / or biochar can be returned to the process together with new combustible material.

[0060] By returning the biochar to the reactor, the process can achieve substantially complete carbon conversion of the feedstock. Depending on the quality of the biochar and market conditions, the biochar can also be used for other purposes. For agricultural feedstocks that are not contaminated with molecules such as heavy metals, the biochar can be returned to the field and used to sequester carbon. For MSW and other contaminated feedstocks, the biochar can be safely sequestered within the asphalt.

[0061] In embodiments, the system has the flexibility to fully convert or partially convert carbon and produce biochar. In particular, an operator can process contaminated feedstock one day for full carbon conversion into syngas product and produce slag as a by-product, and the next day process agricultural residues and produce biochar as a by-product. This provides great flexibility as the operator can choose which feedstock to process based on market conditions.

[0062] This operational flexibility is made possible by the disclosure herein of a novel combination of a moving injection system for the oxidant outlet, which produces slag at high temperatures that solidify to form agglomerates, and a hydraulic ram that allows for removal of the bottom thermally affected layer in the containment structure. It is noted that existing gasifier designs do not allow for this operational flexibility because they are designed to produce either solidified ash or molten slag, and therefore are unable to process a wide range of feedstocks on any given day, nor produce a wide range of co-products (slag and / or biochar) on any given day.

[0063] In either case, in embodiments, it is desirable for the process to result in zero waste to landfills.

[0064] Periodically, the method includes opening the containment structure to recharge with new combustible material. The new material is added on top of any material already in the containment structure. In one embodiment, the material being charged to the containment structure may be compressed either before or after being charged to increase its bulk density and therefore the total mass of material that may be charged to the containment structure. Any known means of compressing biomass and waste materials may be used. After the new combustible material has been added to the containment structure, the containment structure is sealed and the gasification process step sequence is repeated.

[0065] It should be understood that the gasification process may be repeatable by the addition of new combustible material without the step of removing the bottom thermally affected layer. When the slag and char have accumulated to an extent that requires or is desirable for removal, drainage of the bottom layer may be performed.

[0066] Slag is formed during the gasification process in amounts based on the ash content of the feedstock. High local temperatures during gasification melt the ash, which upon cooling forms a slag layer near the bottom of the bed.

[0067] Conventional processes required manual removal of ash or slag by completely emptying the contents of the gasifier. The present process allows for a different means for removing slag and / or char, which has resulted in a significant redesign of the containment structure and the process of its operation. The means for removing slag and / or char is a mechanical removal system that operates after the gasification process and is capable of selectively removing the slag-containing layer near the bottom of the gasifier. When operating the present system, significant time savings and operational benefits can be achieved, which represents a commercial advantage for the operator.

[0068] It should be apparent to one skilled in the art that during normal operation, the bottom layer in the containment structure consists primarily of slag and / or char. However, depending on the operating conditions, the bottom layer solids may also contain, or may only contain, partially converted feedstock, slag, ash, and char. In commissioning operations, unused, unreacted feedstock may be removed from the containment structure. If the containment structure is operating only as a dryer, dry feedstock may be removed from the containment structure using a mechanical solids removal system.

[0069] The mechanical solids removal system includes one or more rams associated with a containment structure. The containment structure may have a top surface, side walls, and a bottom surface on which a lid is disposed. The, or each ram, may be disposed adjacent to a bottom surface of the containment structure. The, or each ram, may be movable within the containment structure to shift, move, extrude, transport, or eject material from a bottom layer of the containment structure. The, or each ram, is configured to move forward into the bed of material and move rearward into a housing. The housing may form part of the containment structure, must be airtight, or may be external to the containment structure.

[0070] The ram may have a top surface, an optional bottom surface, and a ram front surface. The top surface of the ram is preferably the support surface because the ram must move through the material and is retracted as the layer is discharged. As the ram moves forward, material that is not discharged from the containment structure rests on the support surface. As the ram is retracted, thermally affected material, including combustible material, leaves the support surface and falls under gravity to the bottom of the containment structure.

[0071] Each of the rams can be located on a first side of the containment structure. There can be one or more openings on the first side of the containment structure that allow the rams to pass into the containment structure. Optionally, when the rams are not in use, the openings on the first side of the containment structure can be sealed, for example, by a retractable door. The door can be openable to allow the rams to enter the containment structure. The door on the first side of the containment structure can be operated using electronic circuitry. When the rams are not in use, it may be desirable to seal the opening on the first side of the container to protect the ram front from the gasification process. Alternatively, the ram front itself can be a seal for the opening on the first side of the containment structure, with the ram front aligning flush with the opening and forming part of the containment structure wall.

[0072] On the opposite, second side of the containment structure, there may be one or more openings through which the solids are discharged. The or each ram may transmit a force to the bottom layer of solids, which are ploughed towards the openings on the second side where they are discharged. There may be one long opening, or there may be multiple smaller openings. Each opening may be associated with a ram. In some embodiments, if there are multiple openings, the walls provided between each opening may be shaped like a wedge. The wedge may extend inside the containment structure and may function to direct the solids to the openings and / or to break up larger pieces of solids, such as slag, that impact the wedge face.

[0073] To assist with the discharge of the solid waste, the or each opening in the second side of the containment structure may be associated with a passageway or chute that conveys the solid waste by gravity to a bin, conveyor or other collection means. The passageway or chute associated with the opening in the second side of the containment structure may have a cover over the top of the opening to prevent or reduce the possibility of the discharged solid waste being dispersed into the atmosphere as it is discharged.

[0074] Each opening on the second side of the containment structure must have a door. The door must be openable and closable. In the closed state, the door must provide a seal so that the gasification process can also proceed. Providing a door and a cover over the chute / chute can be difficult because there are multiple components all located in the same space. The interior area of ​​the containment structure is best kept as small and tight as possible during gasification, so it is undesirable for the door to be at the end of the chute passage. Therefore, preferably the door is aligned with the second side of the containment structure so that it is flush with the wall of the containment structure when closed. In one embodiment, there is a hinged door that extends from the chute when opened, but can move upward and into the chute when the door is closed for gasification. The door can be of a complementary shape to the interior of the chute. The door can have a trough that allows for a liquid seal around the outer edge of the door when it swings inside the chute. The inward facing surface of the door can be insulated and or coated with a refractory, ceramic or steel liner to protect the door from exposure to the high temperatures of gasification.

[0075] Preferably, the ram front is a flat area that can exert a force against the bottom layer of solids, pushing them in the direction of the ram's movement. The, or each ram, can be operated manually. The, or each ram, can be operated automatically. The, or each ram, can be hydraulically operated. The, or each ram, can be attached to one or more hydraulically operated piston rods. The ram front can be pushed by a piston. The ram front can be pulled by a piston, which in principle has the effect of pulling the solids towards an opening in the second side of the containment structure. This can be done, but it will be understood that the piston is located within the containment structure, which may not be desirable. Each ram can have an operating pressure of up to about 200-300 bar. Each ram can deliver a force of up to about 100 kN per cylinder. This may be increased by a factor of 5-10 in very large reactors. The force delivered by the ram needs to be sufficient to penetrate the solid material and move the underlying layer of solid material under the influence of the ram movement. When subjected to gasification, combustible material can become a heavy mass within the containment structure, and movement of one of the bottom layers requires a large force. Furthermore, the force exerted by the rams needs to be sufficient to allow the rams to be retracted once discharge has occurred. In the preferred embodiment, two pistons are used to move each ram.

[0076] The amount of slag and / or char discharged depends on the area of ​​the ram front. The larger the ram front, the more solids will be discharged. Similarly, the wider the opening on the second side of the containment structure, the more solids can be discharged. The height of the ram front is an important consideration in the design of a mechanical solids removal system. A smaller height requires less hydraulic force to move the ram, but may require multiple strokes of the piston and ram to discharge the desired amount of solid material after each gasification step. On the other hand, a larger height requires more hydraulic force to move the ram and fewer strokes of the piston and ram to discharge the desired amount of solid material.

[0077] In one embodiment, the height of the ram front, measured from the bottom of the containment structure to the top of the ram, is selected or optimized to expel about 5% to 10%, more preferably about 10%, of the material in the containment structure with each stroke of the piston. In one embodiment, the height of the ram front is at least equal to the height of the slag mass formed after gasification. In one embodiment, the height of the ram front is at least 25, 40 or 60 mm.

[0078] It will be apparent that where multiple lances are arranged vertically and the feedstock is a high ash material, the piston and ram may require multiple strokes to completely remove all of the slag produced during the gasification cycle.

[0079] The ram front face can be a flat plate. The ram front face can have a shape that aids in the evacuation of waste materials. In one embodiment, the ram front face can be a plow shape, with two plates meeting at a central point. The ram front face can have a surface pattern or contours that aid in collecting small particles by friction or capturing larger particles and carrying them with the ram front face as it traverses the containment structure during operation.

[0080] There may be one ram that travels from a first side of the containment structure to a second side of the containment structure. If the containment structure is elongated with a pair of longitudinal sides and two short sides, the first side and the second side may be a pair of longitudinal sides. It may be advantageous to arrange the ram so that it can move from one of the longitudinal sides to the other, since the path the ram must travel is relatively short. However, there is an advantage if the ram can be operated between a pair of short sides, since necessarily fewer, or even only one, ram is required to eject the solid material. However, if the ram travels from one of the short sides to the other of the short sides, the path the ram must advance and retreat is long, which may create operational problems.

[0081] There may be multiple rams, each ram alongside one another. In one embodiment, the number of rams in each containment structure is 1-10, more preferably 2-6, and optimally 3-4.

[0082] It should also be understood that if multiple rams are used, they may be operated together as a single unit, or may be operated independently in sequence.

[0083] The dimensions of the reactor will affect the size of each ram. In a pilot reactor, each ram may be at least about 0.5, 0.8 or 1 m across the width of the ram front. If the ram is about 1 m wide and the containment structure side is about 6 m, there could be six rams along the bottom of the containment structure. However, it should be understood that mechanically, the necessary spacing between each ram is required to allow mechanical movement of each ram and provide space for whatever sealing method is used to ensure that the containment structure remains sealed from the outside atmosphere during operation. Preferably, the rams are as close together as possible when placed side by side to avoid any area on the containment structure floor not being coverable by the passage of the rams from one side to the other. Thus, in one embodiment of a pilot reactor, four rams may be used. In one embodiment of a container type reactor, four rams may be used, each with a ram width of about 2.5 to 4 m. In another embodiment of a stick construction reactor, six rams may be used, each with a ram width of about 3 m.

[0084] In one embodiment, at least about 80, 85, 90, 95 or 99% of the bottom floor surface of the containment structure can be covered by the ram movement.

[0085] All of the rams can move from the first side of the containment structure to the second side of the containment structure. Alternatively, some of the rams move from the first side of the containment structure to the second side of the containment structure and other some of the rams move from the second side of the containment structure to the first side of the containment structure. Optionally, the rams alternate direction of movement along the length of the containment structure. An advantage of alternating passes of the rams may be that solid waste not captured or moved by one ram may be collected by its adjacent ram traveling in the opposite direction.

[0086] It should be understood that rams functionally equivalent to those described may also be used. For example, instead of a ram having a ram front that moves in and out of the containment structure, the floor of the containment structure may be a movable shelf. The shelf may have a wall along one side that acts as the ram front. When the ram front is actuated to move forward, the entire bottom of the bottom layer moves out from under the other layers of thermally affected material. As the shelf extends from the containment structure, a mechanism may be provided for scraping solids from the shelf before the system is retracted.

[0087] In an embodiment, the ram can inject gas into the containment structure when stationary, moving, or in any position. The gas can be air, carbon dioxide, nitrogen, or syngas. The gas can be used for heating, cooling, or purging. The ram can be used to inject gas at different positions depending on the ram position to distribute the gas throughout the containment structure.

[0088] In one embodiment, the ram includes one or more openings for injecting heating gas, purging gas and / or cooling gas into the containment structure. In one embodiment, the ram includes one or more gas injectors for injecting cooling and purging gas, whereby the ram is used to cool and purge the sealed containment structure. Additionally, the one or more gas injectors of the ram can be used in any heating step to heat the combustible material, thereby drying the combustible material prior to conversion.

[0089] In one embodiment, if there are openings for injection, heating, cooling or purge gas, the openings may be located at the front of the ram. When not in use, the front of the ram may be recessed against the inner wall of the containment structure to reduce the front temperature during gasification operations.

[0090] In an alternative embodiment, there are one or more gas injectors in the containment structure for cooling and purging and / or heating, but these are not located on or in each ram, but instead are separate from the rams. The gas injectors may be located on the floor of the containment structure below the rams. The gas injectors operating as injectors for cooling, heating and / or purging gas have multiple exit holes through which the heating, cooling or purging gas is distributed over the length of the injector. Furthermore, the exit holes are sized to ensure an even distribution of gas flow into the containment structure.

[0091] In one embodiment, the outlet may be located on the side or bottom of the gas injector to prevent solids in the bottom layer of the bed from entering the gas injector through the outlet when heating, cooling or purge gas is not being injected. Additionally, in one embodiment, a cover may be placed over the gas injector to prevent solid material, particularly char particles, fines and condensed tars, from building up within the gas injector and blocking the flow of heating, cooling or purge gas to the containment structure.

[0092] If the gas injection device is located in or on the containment structure floor, it must be properly designed and made of materials that can withstand high temperatures and abrasion from solid materials when pushed by an adjacent ram.

[0093] When the reactor operates in a batch process, there are several stages of operation: "Charge", "Heating and purging", "Gasification (or production)", "Cooling and purging", "Purge with air", and "Removal". An exemplary embodiment of the process will now be described.

[0094] Filling stage During the filling stage, the containment structure is filled with combustible material to form a bed of feedstock. Prior to filling, the containment structure is purged with air. Filling can be accomplished by using a material handler with a grapple attachment, which is used to grab a bulk of combustible material from a storage pile near the containment structure, lift it over the opening created by the lid, and then discharge it into the containment structure. Alternatively, the combustible material may be filled using a conveyor, crane or bin, or any other means.

[0095] Heating and purging phase With the reactor lid closed and sealed, the reactor is ready for the heating stage, the purpose of which is to heat and dry the feedstock to reduce its moisture content. An inert gas is optionally used to heat and dry the feedstock, as well as to purge oxygen from the containment structure. In some circumstances, air may be used as the heating gas. In this case, an inert gas such as nitrogen is subsequently used to purge all oxygen from the containment structure. In a preferred embodiment, an inert gas is used, heated and circulated in a closed loop system to dry the feedstock.

[0096] Gasification (production) stage Once the bed is dried and purged of oxygen, it is ready to begin producing syngas. The oxidant injection lance is moved from a "fully retracted" position to a "fully inserted" position in preparation for ignition. Ignition of the bed in the reactor can be initiated via a heater in the oxidant injection member or lance. In one embodiment, pure nitrogen is flowed through the oxidant injection lance while the heater is on, and once the required ignition temperature is reached, the nitrogen flow is replaced with the required oxidant, be it pure oxygen, air, enriched air with or without steam impregnation, and gasified by slowly increasing its flow rate. As gasification of the bed progresses near the tip of the lance, the injection lance is semi-continuously retracted to allow gasification of the feed from one end of the containment structure to the other.

[0097] The pressure in the containment structure during operation can be controlled via a pressure control loop that modulates the speed of the syngas blower. The operator can select which reactor is in production mode using a selector block on the control panel. This defines which pressure transmitter is used in the pressure control loop. Individual safety vents can be connected to each containment structure reactor. The vents can have a water seal height of 30 mm (or more) above the vent pipe dip leg providing overpressure protection to the reactor.

[0098] During extended operation, the series of parallel containment reactors can be rotated continuously through operating stages to allow for continuous production of syngas. The raw syngas exiting the production side of the containment reactor can be passed through gas clean-up equipment to process the syngas to reach specifications suitable for use in downstream applications such as electricity production by gas engines, or hydrogen purification or separation, or synthesis of new chemicals or fuels such as methanol, synthetic methane or sustainable aviation fuel using catalytic reactors.

[0099] In one embodiment, the syngas leaving the containment structure is at a temperature between 200 and 500 degrees Celsius. The temperature of the syngas depends on the oxidant used, the composition of the feedstock, the size of the containment structure, and other factors. The temperature of the syngas can be as low as 65 degrees Celsius or as high as 650 degrees Celsius.

[0100] Techniques for purifying syngas at moderate temperatures are well known and one skilled in the art can easily select an appropriate technique. If the syngas temperature is much higher than 80 degrees Celsius, it can be cooled by a liquid quench system, which is simple to implement and robust. The gas purification equipment can consist of a wet electrostatic precipitator (ESP), a syngas blower, a syngas cooler, a sulfur removal bed, and an activated carbon bed. The ESP can remove heavy tar droplets and particulates from the syngas stream, which can be condensed and returned to the reactor for conversion to syngas. The syngas blower can control the pressure in the production reactor by drawing the syngas through the ESP. This can compress the gas slightly, nominally to 2 kPag, to generate the pressure required to flow the gas through the syngas cooler and adsorbent bed and make it positive for use in subsequent downstream applications. The syngas cooler further reduces the temperature of the syngas to near ambient conditions and collects any additional condensate that forms due to this temperature change. Activated carbon beds can remove impurities such as heavy metals and halide compounds, hydrogen chloride (HCl), chlorine (Cl2), fluoride (F), etc. Sulfur removal beds preferentially remove sulfur compounds such as H2S.

[0101] It is well known to those skilled in the art that different syngas cleaning methods are selected depending on the concentration of contaminants in the syngas and the required purity of the syngas for the selected downstream application. Different syngas cleaning methods are also selected based on the scale of processing. Some methods work well at low temperatures and atmospheric pressure, while other methods work well at high temperatures and / or pressures. In general, a syngas cleaning method for syngas derived from waste feedstocks must be able to process light and heavy tars, sulfur, chlorine, heavy metals, volatile organics, and dioxins / furans.

[0102] Cooling and Purging Phase Once gasification is complete, the feedstock is cooled and the syngas is purged by circulating an inert gas such as nitrogen. The syngas from the cooling and purging stage of one reactor can be mixed with the product syngas from another reactor that is now operating to produce syngas by gasification. The degree of cooling will normally continue until the material remaining in the containment structure reaches a temperature at which it will not begin to burn or smolder after exposure to air at ambient temperature.

[0103] Air purge stage Once the contents of the containment structure have cooled sufficiently, air may be injected into the reactor and purged through the vent and / or closed loop gas circuit until trace elements such as carbon monoxide are below threshold concentrations, typically 1% by volume or less.

[0104] Removal stage If solids removal is desired at this point, once the containment structure has been purged with air, it may be opened and the waste removal system activated. The opening in the second side of the containment structure is opened. The rams are then each activated to move the bottom layer of solid material to be discharged.

[0105] Multiple containment reactors can be operated in parallel. Each can be designed to operate with another process as a continuous process. One or more reactors are in gasification (production) mode converting feedstock material to syngas, while other reactors are progressing through a step sequence of loading, heating and purging, cooling and purging, purging with air, and unloading in preparation for being placed in gasification (production) mode after they reach the heating and purging stage.

[0106] Thus, in a third aspect, there is provided a system for gasifying a combustible material to produce gas, comprising: a plurality of sealable containment structures, each having a first side and a second side disposed along either side of an elongate axis, each containment structure configured to operate the method of the first or second aspect of the invention; each containment structure capable of being filled with a combustible material during a filling stage to provide a filled containment structure; each dry containment structure configured to produce syngas by gasification during a production stage; each containment structure configured to have solid material removed therefrom during a removal step; Equipped with A system is provided in which multiple sealable containment structures are simultaneously operable such that at any given time a first containment structure is in a production stage while at least a second containment structure is completing a production stage, such that syngas can be produced continuously from the multiple sealable containment structures.

[0107] Optionally, other steps that may be included are: Each filled containment structure may be purged and dried during a heating and purging step to provide a dry feedstock within the containment structure prior to producing syngas; After the manufacturing step, each containment structure may be purged and cooled during a cooling and purging step. Includes.

[0108] Each reactor can have an injection side and a production side. On the injection side, an injection lance can be installed that is connected to an oxidant injection skid via a flexible hose connection. This flexible connection allows for intermittent or continuous retraction of the oxidant injection lance as the gasification reaction progresses, allowing for moving injection horizontal gasification (MIHG). This retraction moves the gasification zone backward to access new material. A hydraulic system with a controller can be used to set the retraction distance and frequency. The retraction displacement can be measured and recorded for information.

[0109] On the production side of the reactor, a raw syngas pipe connects the reactor to gas clean-up equipment.

[0110] The syngas production rate from the MIHG containment reactor depends on the oxidant injection rate, the oxidant composition and the feed composition, however, by connecting the production flow rate signal to an oxidant flow ratio controller, the oxidant rate can be adjusted to maintain a set production rate of syngas.

[0111] The quality of the syngas can be monitored using an online analyzer. A sample point can be placed on the common raw syngas line at the containment structure reactor outlet upstream of the gas cleanup unit. The online analyzer can be equipped with an automatic gas conditioning bubbler and filter to condition the syngas before feeding it to the online analyzer. This analyzer can measure the composition of CO, H2, CO2, O2 and CH4 in real time. The output of this analyzer can be fed to a controller for trending and control action. The oxygen concentration at the gasification reactor discharge is an important safety parameter to avoid the formation of flammable mixtures in the system.

[0112] The temperature profile throughout the containment structure can be monitored by thermocouples. The thermocouples may be located within the walls of the containment structure or may be movable and insertable into the feed bed. In one embodiment, there may be as many as 18 thermocouples spaced throughout the length of the MIHG reactor structure. There may be three sets of three thermocouples per reactor side, located at the top, middle and bottom of the reactor. These provide temperatures related to the roof, sidewalls and bottom at three intervals along the length of the containment structure. Thermocouples on the oxidizer lances can also be used to confirm ignition and monitor oxidizer injection. Thermocouples on the syngas outlet pipes can be used to confirm the temperature of the syngas, which is important to keep above a minimum to prevent heavy tars from condensing and forming blockages in the pipes.

[0113] Embodiments of the present invention will now be described with reference to the accompanying drawings, which are not drawn to scale and are merely exemplary. [Brief description of the drawings]

[0114] [Figure 1] FIG. 1 is a process flow diagram illustrating steps in a process according to one embodiment. [Diagram 2] FIG. 2 illustrates a side view of a containment structure according to one embodiment. [Diagram 3] FIG. 3 is a side view of the structure of FIG. 2. [Figure 4] FIG. 1 is a perspective view of one embodiment. [Diagram 5] FIG. 3 is a top view of the containment structure of FIG. 2. [Figure 6] FIG. 2 is a schematic side view of one embodiment. [Figure 7] FIG. 13 is a schematic side view of an alternative embodiment. [Figure 8] FIG. 3 is a schematic diagram of temperatures in the embodiment of FIG. 2 during manufacture. [Figure 9] FIG. 1 is a process flow diagram according to one embodiment. [Figure 10] FIG. 1 shows an operational diagram of an embodiment with two gasifiers operating in parallel. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0115] The present disclosure includes a batch method for gasifying a material by injecting air or oxygen into a limited volume of a carbonaceous material, which may be biomass, and collecting the product gas. According to an exemplary embodiment with reference to Figures 1-10, the method includes loading a containment structure 110 with a carbonaceous material, such as biomass or a combustible material 18, which may include collecting and storing. In addition to biomass, the feedstock may be any applicable material or mixture thereof, as previously described in this disclosure.

[0116] With reference to Figure 1, the main stages of operation of the containment structure are shown, which include the following sequence: 1. Fill the feedstock 2. Heat and purge the containment structure with inert gas 3. Gasify the feedstock using a mobile injection system to continuously produce syngas 4. Cool and purge the containment structure 5. Purge the containment structure with air 6. Use a ram to remove the slag and / or char

[0117] In an industrial environment, the sequence of operations is repeated many times to convert a desired amount of feedstock into syngas as well as slag and char. Continuous syngas production is possible when two or more containment structures operate as a system.

[0118] 2-9 for an example of a system 100 including a containment structure 110 configured to produce gas from combustible material 18. The combustible material 18 may be loaded into the containment structure 110 as received or may be processed by chipping, grinding or compacting to increase the bulk density and homogeneity of the feedstock. The combustible material 18 may include unprocessed, irregular and / or oversized material. It will be understood that the combustible material 18 may include other components such as water or small amounts of other particulate material. By-product liquids 134 separated from the syngas may also be recycled and mixed with the combustible material 18 prior to gasification.

[0119] The containment structure 110 may be an elongated rectangular container. The containment structure may have a pair of short sides 10, 10' and longitudinal sides 12, 12'. The longitudinal sides are so named because they extend along the longitudinal axis of the containment structure 110. The containment structure 110 also has a base or bottom or floor 14. The containment structure 110 is typically placed on a solid surface, such as the ground. The containment structure 110 may be fabricated from common engineering materials, including steel, concrete, and refractory. There may be one or more legs 16 to elevate the containment structure 110 off the ground, if desired.

[0120] The dimensions of the containment structure 110 depend on the volume required. Larger containment structures provide longer operating times, but the capital costs will be higher than smaller structures. A typical storage volume of the containment structure 110 may be in the range of about 100 m3 to about 10,000 m3. A typical operating time may be in the range of about 1 day to about 1 week, but is not limited to this. Typical dimensions of a commercially sized containment structure may be in the range of about 2 meters to about 10 meters width, about 2 meters to about 20 meters height or depth, and about 6 meters to about 40 meters length.

[0121] The system 100 includes an oxidant supply mechanism 20 in the form of an injection member 20 configured to supply or inject oxidant into the containment structure 110. Suitably, the oxidant is supplied into the sealed containment structure 110 such that it sequentially contacts the combustible material 18 at multiple points. The injection member 20 may be a duct, conduit, pipe, tube, channel, or the like. The injection member 20 may be in the form of an injection lance 20 having an injection end or tip 24. The injection lance 20 is preferably inserted into the combustible material 18 and aligned along the axis of the containment structure 110. The oxidant is supplied into the sealed containment structure 110 such that it sequentially contacts the combustible material 18 at multiple points. Depending on the width and height of the containment structure 110, multiple injection lances 20 may be used to improve distribution of the oxidant. Typical oxidant injection rates for commercial applications may be in the range of about 100 to about 30,000 Nm3 / hr depending on the dimensions of the containment structure 110 and the desired gas production rate.

[0122] At least one production pipe 22 may be installed at the end of the gasifier opposite the injection end. The production pipe 22 may be vertical or inclined and shall be designed to handle the hot product gas from the gasifier, typically at temperatures in the range of about 100°C to about 700°C. The production pipe may be made of carbon or alloy steel with welded joints. The base of the production pipe 22 may be perforated to avoid blockages. If necessary, the product gas may be cooled by injecting water or other fluids directly into the gas or by circulating cooling water through the double-walled production pipe. Direct injection of water is simpler and less costly than indirect cooling, but this increases the moisture content of the gas, resulting in additional condensate production when the gas is cooled in subsequent gas cleaning equipment such as the ESP. Wastewater produced from gas cooling and cleaning may be a substitute for fresh water depending on the wastewater characteristics. Depending on the dimensions of the containment structure 110, multiple production pipes may be required.

[0123] Other equipment may be installed within the containment structure, including an ignition device, cooling / quench water pipes, and monitoring devices such as thermocouples. In a preferred embodiment, the ignition device is integrated into the tip of the lance 20.

[0124] At least a portion of the top of the containment structure 110 should be open during the filling or refilling phase and should be completely sealed from the atmosphere during the gasification phase. The top cover 34 can be in the form of a movable cover plate 34 of hinged, sliding or loose design, can be made of non-combustible material such as steel, concrete or refractory, and can be used to seal the top of the containment structure 110. In addition to sealing the containment structure 110 from the atmosphere, the cover 34 is also used to reduce heat loss and therefore must have insulating properties. The cover plate 34 is typically exposed to the high temperature syngas inside the containment structure and requires suitable materials such as high temperature rated cement or refractory or stainless steel. When in the closed position, a portion of the cover 34 extends into a liquid 38, such as water, contained within the trough 36. In one embodiment, the sealing liquid 38 is water, which may be contaminated with light and heavy tars condensing from the syngas over time and / or may be partially replenished with bits of feedstock that may accidentally flow in during filling. Experience with the water seal 38 indicates that contamination with liquids or solids is not an operational concern and the trough 36 can be easily cleaned of any debris or contaminated liquids.

[0125] Once the containment structure 110 is evenly refilled with combustible material 18, the top of the containment structure 110 may be closed and all openings sealed from the atmosphere. With the reactor lid 34 closed and sealed, the reactor 110 is ready for the heating and purging phase. An inert gas is optionally used to heat and dry the feedstock, as well as to purge oxygen from the containment structure 110. The combustible material may be preheated and predried prior to gasification using product gases, or waste heat from downstream processes such as power generation, or any other dedicated heat source. This can be accomplished by contacting the combustible material with hot syngas, combustion exhaust gases or preheated air or inert gas to evaporate excess moisture. The heating / drying medium may be introduced into the material through the oxidizer injection pipes 20, through an outlet in the ram 168, or through other outlets that distribute the heated gas into the containment structure and are installed specifically for this purpose. In a preferred embodiment, the heated gas is fed into the containment structure through one or more gas injectors 35 located on or in the floor 14 of the structure. During the heating and purging stage, the inert gas has its pressure moderately increased by blower 182 and is heated by heater 184, which in a preferred embodiment utilizes waste heat from downstream user 132. The moist heated gas is collected and sent to cooler 170 where the water is condensed, and to separator 172, where water 174 is separated from the heated gas and re-enters the closed circuit for reuse. The amount of moisture removed from the feed during the heating and purging stage can be easily calculated by reading the level of condensate removed in the separator.

[0126] Once heating and purging is complete and start-up of the gasification operation is desired, the injection lance 20 can be fully inserted into the bed of feedstock 18 using a hydraulic mechanism or other method. To start up the gasification, an ignition sequence can be performed by first establishing a flow of inert gas from the injection pipe 20 to the production pipe 22, and then igniting the combustible material 18 near the exit of the injection pipe 20 using any suitable means as further described herein. Initial ignition of the combustible material 18 can be achieved by a variety of means including the introduction of hot coal, injection of gaseous or liquid fuels including, but not limited to, methane, LPG or fuel oil, etc., use of pyrophoric substances including, but not limited to, silane or triethyleneborane gas, etc., or electrical resistance heating. An ignition source can be inserted through the injection pipe or production pipe, or via a separate ignition pipe. The combustible material 18 may also be ignited by using a burner with an extension handle prior to closing the final cover plate. Once ignited, the process is self-sustaining and does not require an additional ignition energy source. However, if the combustion zone becomes extinguished, reignition may be required using methods similar to the initial ignition.

[0127] In a preferred embodiment, the lance tip 24 contains an electric heating element that is used to heat the inert gas that passes from the injection member 20 through the oxidant outlet at the tip, into the bed of feedstock 18, and then into the syngas outlet pipe 22. Once the zone around the lance tip 24 has been heated by the inert gas above the autoignition temperature of the feedstock, the inert gas can be slowly replaced with an oxidant, such as pure oxygen, by manipulating the flow control valve. This initiates the combustion and gasification reaction in the vicinity of the lance tip 24.

[0128] An injection lance 20 is used to supply or deliver oxidant 21, which can be air, oxygen, or a mixture thereof. Air or oxygen may be supplied by any suitable means, such as an air blower or compressor and oxygen production or enrichment by membrane, vacuum / pressure swing adsorption, or cryogenic air separation. The oxidant may be preheated to improve gasification efficiency using waste heat from the raw syngas or downstream sources. Water or steam may also be injected with the oxidant as a gasification reagent or for cooling purposes.

[0129] The injection lance 20 is preferably made of carbon or alloy steel. Suitable designs for the injection lance 20 include coiled tubing, flexible tubing, or joint pipes using flanges, threaded couplings, or clamps, as used in oil and gas applications, to provide a means to retract or shorten the injection lance and thus relocate the injection point in the gasifier. Methods for retracting the injection point include shortening the injection lance by removing the joint, intentionally breaking the joint by heat or mechanical means, burning through the injection lance using a burner inserted in the injection lance, or by winding it onto coiled or flexible tubing. Due to the low operating pressures, the size of the injection lance may be too large for coiled tubing, and therefore a preferred design may use jointed or flexible tubing. Reusing the injection lance 20 reduces operating costs, so retracting the pipe by mechanical means and removing the joint to shorten the pipe are preferred. In a preferred embodiment, a continuous section of tubing or pipe may be used for the injection lance. A nozzle or lance tip 24 may be attached to the end of the injection lance 20 to increase or disperse the velocity of the oxidant exiting the pipe, promoting more efficient mixing and gasification. In a preferred embodiment, the lance tip 24 may include multiple oxidant outlets. In another preferred embodiment, the distance the injection member 20 is retracted during each retraction sequence is set equal to the distance between adjacent oxidant outlets on the lance tip. This ensures that gasification zones formed from two or more adjacent positions of the injection member overlap, helping to ensure that the gasification process is not quenched during the movement of the injection member. In another embodiment, the injection member is retracted very slowly, so that the gasification zone created by the oxidant outlet nozzle has time to naturally adjust its position as the injection member moves.

[0130] Alternative injection lance 20 designs include a fixed or retracting pipe containing a series of holes or nozzles that create multiple simultaneous injection points along its length. If the nozzles are located along the entire length of the injection lance, the gasification process can proceed evenly along the length of the gasifier and no injection point retraction is required. A fixed injection lance does not require joints and may be fully welded. This design also has the benefit of creating an extended high temperature zone along the length of the gasifier resulting in greater destruction of tars. Syngas produced at an injection point near the gasifier inlet flows toward the production pipe and is reheated as it passes through other injection points located downstream. This design can also be used to create an injection point near the gasifier outlet to increase the syngas temperature and promote thermal destruction of tars.

[0131] In one embodiment, a specific placement of the oxidant outlet nozzle is made at the lance tip 24 and along the length of the oxidant injection member 20. In one embodiment, this placement is made to simultaneously increase the conversion of the feedstock 18 to syngas and minimize the amount of tars in the syngas.

[0132] In one embodiment, but not necessarily a preferred embodiment, the injection lance 20 is placed inside a perforated liner pipe (not shown) to prevent friction against the injection lance during retraction due to the weight of the biomass on the pipe and to maintain a flow path to the production pipe. The perforated liner may be made of carbon or alloy steel and may have perforations in various patterns and various hole shapes and sizes. Typically, the perforations are staggered to provide equal open area in the range of 30% to 80%. The perforated liner may extend to the end of the injection lance or may extend to the base of the production pipe and may be connected to the base of the production pipe. The perforated liner may include a solid section to seal overlying biomass from the injection lance at a desired location and to create a seal at the point where the perforated liner exits the containment structure 110. A dynamic seal is also required between the injection lance 20 and the liner near the entrance to the containment structure 110 to prevent oxygen ingress and syngas leakage through the annulus during retraction.

[0133] Direct injection of water into the gas can be accomplished by a quench pipe (not shown) that conveys water to the base of the production pipe and injects the water through spray nozzles either upstream of the production pipe or inside the inlet of the production pipe. The spray nozzles are sized to produce a fine enough spray of water to rapidly vaporize and cool the gas to the desired temperature within a certain distance. In one embodiment, a hydrocarbon or other fluid is used in place of water in the quench pipe.

[0134] A typical gasification step involves one or more injection members 20 being fully inserted into the combustible material, which may be biomass 18. The biomass is ignited using the methods described above to form one or more gasification zones. These gasification zones are then moved backward through the bed of biomass 18 from the syngas production outlet end to the injection end by moving or retracting the injection members 20. When each injection member 20 reaches the injection side or fully retracted position and further retraction while gasification continues is no longer feasible, the oxidant injection flow is stopped and the process transitions to a cooling and purging phase.

[0135] During the cooling and purging phase, an inert gas 180 at ambient temperature is injected into the bed of feedstock in the containment structure 110' with its pressure moderately increased by a blower 182 and with the heater 184 not operating or bypassed. The cold inert gas is distributed within the containment structure. In one embodiment, the inert gas is passed through a ram 146 acting like a plenum via a pipe extending from a housing (not shown) and then injected into the containment structure via an outlet 168 at the ram front face 152. In another embodiment, the inert gas is injected through a dedicated gas injection member 35 located in or on the floor 14 of the containment structure. During the initial stages of cooling and purging, the syngas remaining from the gasification stage is purged from the containment structure through the production pipes 22. In a preferred embodiment, this syngas is mixed with the syngas currently being produced by another containment structure 110. Once the syngas from the containment structure 110' has been removed, the cooling and purging step may continue by the gas exiting the reactor into a cooler 170 and then purging to the atmosphere via a vent. In one embodiment, the purge gas is substantially entirely an inert gas and is vented directly to the atmosphere via a vent (not shown) connected to the containment structure.

[0136] After the cooling and purging with inert gas is completed, the containment structure can be purged with air using the same equipment. In one embodiment, air 181 is moderately increased in pressure by blower 181 and injected into the containment structure via any of the means used for inert gas. At this stage, heater 184 is not operated or air flow bypasses heater 184. Once the containment structure 110 has been purged with air, mechanical solids removal system door 162 can be moved from a closed position to an open position to expose an opening for discharging solids. Hydraulic piston rod 166 operating in hydraulic cylinder 155 can then be actuated to push the bottom solid layer of material in floor 18 from the bottom of containment structure 110 using ram 146. This bottom layer of solid material is then discharged through opening 156 via chute 160 and may fall to the ground or, more typically, is collected in a bin or conveyor located below the discharge point of containment structure 110.

[0137] During the gasification process, solid agglomerates of material such as char 141, ash 142 and or slag 143 may be formed in amounts based on the inorganic content of the feedstock 18. High local temperatures during gasification melt this ash and upon cooling form a slag layer 143 at the bottom of the containment structure as seen in Figures 6 and 8. The solids removal system includes one or more rams 146 associated with the containment structure 110. The containment structure 110 may have a top surface on which the lid 34 is disposed, side walls 10, 10' and 12, 12', and a bottom surface 14. The or each ram 146 may be positioned adjacent the bottom surface 14 of the containment structure 110. The or each ram 146 may be movable within the containment structure 110 to shift, move, extrude, transport or eject solid waste from the bottom surface 14 of the containment structure 110. Each ram 146 is housed within a housing structure 147 outside of the containment structure 110.

[0138] The ram may have an upper surface 148, a bottom surface 150, and a ram front surface 152. The upper surface 148 of the ram 146 is preferably a support surface because the ram 146 must move through the combusted material 18 into the containment structure 110 and then retracted once the solid waste 142 has been discharged. As the ram 146 moves forward, material 18 that is not discharged from the containment structure 110 rests on the support surface 148. As the ram 146 is retracted, the thermally affected material, including combustible material, leaves the support surface 146 and falls under gravity to the bottom 14 of the containment structure 110.

[0139] Each of the rams 146 may be disposed on a first side X of the containment structure 110. There may be one or more openings 154 in the first side of the containment structure 110 to allow the rams 146 to pass into the containment structure 110. Optionally, when the rams 146 are not in use, the ram front faces 146 themselves may be part of a seal for the openings 154 in the first side X of the containment structure 110, with the ram front faces 152 aligned flush with the openings 154 and forming part of the containment structure wall 110 (see FIG. 6 ). In this embodiment, an appropriate sealing system (not shown) must also be installed to ensure that the containment structure remains airtight.

[0140] On the opposite side Y of the containment structure, i.e., the second side Y from which the solid materials 141, 142, 143 are discharged, there may be one or more openings 156. The or each ram 146 may transmit a force to the solid materials 141, 142, 143, which are ploughed towards the openings 156 on the second side Y where they are discharged. In some embodiments, when there are multiple openings 156, the walls provided between each opening may be shaped like a wedge 158. The wedge 158 may extend inside the containment structure 110 and may function to guide the solid materials towards the openings 156 and or to break up larger pieces of solid material in the form of ash 142 or more typically slag 143 that impact the wedge surface 158.

[0141] To aid in the discharge of the solid materials 141, 142, 143, the or each opening 156 in the second side Y of the containment structure 110 may be associated with a passageway or chute 160 that conveys the solid materials by gravity to a bin or other collection means. The passageway or chute 160 associated with the opening 156 in the second side Y of the containment structure 110 may have a cover 160 covering the top of the opening to prevent or reduce the possibility of the discharged solid waste 141, 142, 143 dispersing into the atmosphere as it is discharged. This is particularly important with respect to char 141, which may consist of fine and particulate matter.

[0142] Each opening 156 on the second side Y of the containment structure 110 has a door 162. In one embodiment, there is a hinged door 162 that extends from the chute 160 when open, but can move upward and into the chute 160 when the door 162 is closed for gasification. The door 162 can be shaped complementary to the interior of the chute 160. The door 160 can have a trough shape 164 that allows a liquid seal 164 to form around the outer edge of the door 162 and the inside of the containment structure as it swings inwardly into the chute 160 (see FIG. 7 ).

[0143] Preferably, the ram front face 152 is a flat area that can exert a force against the solid waste materials 141, 142, 143 to urge them in the direction of movement of the ram 146 towards the opening 156. The, or each, ram can be attached to one or more hydraulically actuated piston rods 166. The ram front face 152 can be pushed by the piston rods 166.

[0144] The amount of thermally affected combustible material discharged as solid material on each stroke of the piston depends on the area of ​​the ram front face 152. The larger the ram front face, the more solid waste is discharged. The ram front face 152 can be a flat plate. The ram front face can have a shape that aids in the discharge of waste. In one embodiment, the ram front face can be a plow shape, with two plates meeting at a central point. The ram front face can have a surface pattern or contours that aid in collecting small particles by friction or capturing larger particles and carrying them with the ram front face as it traverses the containment structure during operation.

[0145] There may be one ram 146 that travels from a first side X of the storage structure 110 to a second side Y of the storage structure 110. If the storage structure is elongated with a pair of longitudinal sides 12, 12' and two short sides 10, 10', then the first side X and second side Y may be a pair of longitudinal sides 12, 12'. Because the path that the ram must travel is relatively short, it may be advantageous to position the ram movably from one of the longitudinal sides to the other.

[0146] There may be multiple rams 146, each ram alongside one another. For example, four rams 146 are shown in Figures 2 and 5. Some spacing is needed between each of the rams 146 to allow for their mechanical movement and to allow for any deviations in motion. Preferably, the rams 146, when placed alongside one another, are as close together as possible to avoid any area on the containment structure floor 14 not being coverable by the passage of the rams 146 from one side to the other.

[0147] 6 and 7, a series of cross-sectional schematic diagrams of the containment structure in a preferred embodiment of the hydraulic cylinder 155, hydraulic piston rod 166 and ram 146, collectively referred to as the hydraulic ram, are shown. FIG. 6 shows a schematic diagram of the solid material door 162. The door can be shaped to align with the chute 160 and form a liquid seal 164 between the opening for the door 162 in the containment structure 110. The door 162 can be opened by rotation about a pivot point as shown. In the fully open position, the door 162 can rest in an upside-down position outside the chute 160, thereby creating a large opening for solids to exit the containment structure 110. The shape of the door 162 and the nature of the liquid seal 164 allow the liquid within the seal to be removed and replaced before or after opening the door.

[0148] 7 and 9, the process steps required in a closed loop drying system are shown. An inert gas 180, such as nitrogen, or air 181 is brought to pressure by a blower 182 and passed through a heater 184 to raise its temperature from near ambient to 150 degrees Celsius. In one embodiment, the heater 184 is a heat exchanger that heats the inert gas 180 or air 181 using waste heat from downstream users 132 located elsewhere in the process, such as extraction of waste heat from a gas engine or syngas boiler. The high humidity gas is collected towards the top of the containment structure and passed through a cooler 170 to condense the moisture, which is split into water 174 and gas in a separator 172, the water 174 being collected and the gas being reused in the blower 182.

[0149] In an embodiment, as seen in FIG. 7, the ram 146 can inject gas into the containment structure 110 when stationary, moving, or in any position. The gas can be air, nitrogen, carbon dioxide, or syngas. The gas can be used for heating, cooling, or purging. The ram 146 can be used to inject gas at different positions depending on the ram position to distribute the gas throughout the containment structure 110. In one embodiment, the ram 146 includes one or more openings 168 for injecting heating gas, purging gas, and / or cooling gas into the containment structure 110. There can be one or more openings 168. As shown in FIG. 7, the openings can be provided in the ram front face 152. The gas may be distributed to the ram 146 in many different ways. In one embodiment, the gas is injected into the space formed by the housing 147 and the hydraulic piston rod 166 and transferred to the openings 168 via conduits in the ram 146. In another embodiment (not shown), the gas passes through a fixed pipe in the housing 147 and enters a plenum that is formed inside the ram 146 as it moves. The length of the fixed pipe is selected to allow gas to be discharged into the ram 146 when the hydraulic piston rod 166 is in both the retracted and extended positions.

[0150] The inert gas or air outlet holes 168 can be designed so that the gas is distributed evenly across them, and the outlet holes 168 themselves may be oriented to face downwards from the ram front face 152. This protects the outlet holes from solid debris or other material that may have entered the ram and interfered if the outlet holes were oriented in another way, for example directly through the outlet holes to the front face 152 of the ram. The hot inert gas or air heats the feedstock 18 and releases moisture, which is carried out of the reactor through an appropriately sized duct located above the top level of the feedstock. This high humidity gas is sent to a cooler 170 where it is condensed and then sent to a separator 172 where it is separated from the gas as liquid (water) 174. The gas is then sent back to the blower and the cycle repeats. Obviously, to form a closed loop, all components of this heating or cooling system need to be airtight and there are seals everywhere with the outside atmosphere.

[0151] Referring now to FIG. 8, a schematic cross-sectional view of the containment structure during the gasification stage operation is shown. Oxidant is injected through the injector 20 and exits the lance tip 24 into the bed of solid material, forming a high temperature gasification zone around the injector. In the immediate vicinity of the lance tip 24, the reaction of the oxidant with the char 141 formed in the thermally affected layer from the previous gasification run forms a high temperature zone of over 1200 degrees Celsius. This zone is high enough to melt the inorganic material in the char 141 and form slag agglomerates 143 in Zone C. If the peak temperature is lower, ash 142 may form in Zone C. Outside of the peak temperature zone, there is a lower temperature zone as shown. In the zone of temperatures above 800 degrees Celsius, carbon dioxide and steam react with the char 141 to form the primary products of syngas, i.e., carbon monoxide and hydrogen, by well-known gasification reactions. Further into the biomass 18, there is a low temperature zone. At temperatures above about 400 degrees Celsius, most biomass and waste materials pyrolyze to release volatile molecules that form tars, hydrocarbon molecules containing 1-100 carbon atoms each, and carbon monoxide, carbon dioxide, hydrogen, and steam, forming char 141 in zone B. At lower temperatures, the biomass 18 dries and may shrink and change shape in the presence of moderate temperatures. Thus, thermally affected layers in turn are created by zones of elevated temperature emanating from the vicinity of the lance tip 24. There is no exact description or definition or shape of each layer, but observations generally show that the layers are horizontally oriented with the greatest change in the vertical direction. The more highly affected layers are generally located toward the bottom of the containment structure, while the less thermally affected layers are at the top of the containment structure. The gas produced from all temperature zones, collectively known as syngas, travels through the thermally affected material to the syngas production pipe 22. These thermally affected zones also extend laterally, with the less affected thermal layers closer to the walls of the containment structure.

[0152] As the oxygen injection member 20 is retracted, the high temperature zone is gradually moved through the biomass 18, producing thermally affected layers, in particular char 141 and slag 143. As can be seen from the schematic, slag 143 forms in zone C, adjacent to the oxidant injection member, and is one of the lowest thermally affected layers. While char 141 forms in zone B, above zone B, the biomass 18 experiences temperatures below about 400 degrees Celsius and is therefore moderately affected by thermal treatment, such as torrefaction, mild pyrolysis and water evaporation. It is clear that the nature of the changes due to thermal treatment in the various zones shown in the schematic of FIG. 8 depends heavily on the composition of the feedstock. If the feedstock consists mainly of plastics, the thermal decomposition will be more intense at lower temperatures than if the feedstock is mainly biomass.

[0153] During the unloading stage, the bottom layer of slag 143 and char 141 are discharged from the containment structure 110 by ram 146. Referring to FIG. 9, the slag and char 144 may be collected as a mixture in a bin or conveyor and then separated in a separator 190 to form slag 141 and char 143. The char 143 may be recycled to the gasifier 110' during its loading stage. The separator 190 may be a screen or a series of screens, or any other device capable of separating small char particles from larger slag pieces, or light char particles from dense slag pieces. In an embodiment, the char 143 may be stored and used for other purposes. For example, it may be returned to the soil to sequester carbon, or to be used as a base material for fertilizer, or may be recycled in combination with asphalt for reuse in road construction and carbon sequestration. In addition to returning the char 143 to the gasifier 110' to produce more syngas, it is clear that there are many potential uses for the char 143.

[0154] Continuing to refer to FIG. 9, the product gas may be directed to the vent 126 first during ignition due to the oxygen in the gas and the potential for a potentially explosive gas mixture. Once positive ignition is confirmed and the oxygen content in the product gas is below a safe limit, the gas may be sent to a flare 128 and the oxidant injection rate may be increased to the normal design rate for gasification. Once the syngas quality is acceptable, the raw syngas 131 may be sent to downstream gas cleanup 130 to produce clean syngas 133 for end users 132. The tar-water 134 residue from the gas cleanup process 130 may be recycled to the gasifier 110 during gasification operations. The appropriate injection rate depends on the size of the containment structure 110, the required gas production rate, and the kinetic limitations of the gasification process, including heat and mass transfer limitations and the reactivity of the biomass. In one embodiment, the tar-water 134 and char 143 may be mixed with a portion of the feedstock 18 to form a slurry mixture that is charged to the gasifier 110' as a solid. This embodiment has the advantage that no dedicated injection lines, control valves, and flow measurement devices are required to control the fluid recycle of the tar-water 134.

[0155] Typically, the highest temperatures occur near the injection point, which can be seen in the schematic diagram of FIG. 8. This is due to the combustion of biomass 18 and syngas around the injection point in Zone A. The heat generated from the exothermic reactions causes the drying and pyrolysis of the combustible material 18 around and downstream of the combustion zone, which is turned into char, and the char is converted to syngas by gas-solid reactions including reactions with H2, CO2, and H2O. Gas-phase reactions also occur, including water-gas shift and methanation reactions. The syngas naturally cools as it flows toward the production pipe 22, but further cooling of the gas may be required due to material limitations in the production piping and downstream equipment. The hot product gas is typically composed of a mixture of N2, H2, CO, CO2, CH4, H2O, tar, and other minor constituents.

[0156] During normal gasification operation, the raw syngas 131 is directed to gas cleanup equipment 130 and downstream users 132. The operating pressure of the gasifier 110 and the pressure of the product gas are close to atmospheric to avoid gas leakage and air ingress into the containment structure 110. If the fuel 18 around the injection point 24 is consumed, the gasification efficiency decreases and the quality of the product gas decreases. To avoid this and maintain high syngas quality, the injection point 24 can be periodically or continuously retreated to consume new combustible material 18. The flow rate and composition of the syngas product gas can be controlled by varying the oxidant injection rate, composition and injection location. In one embodiment, at least 30% to no more than 80% of the carbon in the feedstock is converted to syngas in each gasification cycle. In a preferred embodiment, more than 50% of the carbon in the feedstock is converted to syngas in each gasification cycle. If the gasifier 110 needs to be shut down, the oxidant injection can be stopped and the excess product gas can be released. The method of the present disclosure can include stopping the oxidant injection to quench the gasification reaction. If necessary, water can be injected to quench and cool the gasifier after oxidant injection is stopped.

[0157] The hot raw syngas can be cooled and cleaned according to typical industrial practices for biomass-derived syngas. Due to the long residence time and low velocity in the gasifier, the production of heavy tars and fines can be significantly lower than other biomass gasifiers, especially fixed-bed and fluidized-bed gasifiers operating at low to moderate temperatures. This reduces the cost and complexity of the gas cleaning process.

[0158] Once the injection member 20 has been retracted to its fully retracted position and the combustible material 18 has been partially consumed, the containment structure 110 is cooled and purged with inert gas. In industrial facilities, the syngas produced during purging is first mixed with the raw syngas from the operating gasifier 110'. Once the syngas is highly diluted and mainly inert gas, it can be sent to a vent or flare. Purging with air can oxidize any harmful flammable gases and liquids, but care must be taken to ensure that explosive mixtures are not formed. Once the atmosphere in the containment structure 110 is safe, the top of the containment structure 110 is opened to allow for the reinstallation of equipment and re-stocking of combustible material 18 in the form of biomass material.

[0159] FIG. 10 shows an operational schematic of two gasifiers or containment structures, called reactor 1 and reactor 2, over a time period represented by ten separate time segments. Focusing first on reactor 1, in time segment 1 the reactor is filled with feedstock. In time segment 2 a heating and purging phase is performed to dry the feedstock, remove moisture, and purge the containment structure to remove any oxygen present. Once the purging procedure is completed, ignition can be initiated to lead to the gasification operation phase (five steps) that extends from time segment 3 to time segment 7. Once gasification has stopped, a cooling and purging phase is performed in segment 8, and purging with air is completed in time segment 9. Finally, in time segment 10, an unloading phase involves opening the solids removal door and using a ram to eject solid material, mainly in the form of slag and char, from the reactor. The operation phase is then repeated from time segment 11 onwards. For reactor 1, syngas production occurs from time segment 3 to time segment 7. Focusing now on the operational steps of Reactor 2, it can be seen that the exact same operational steps are carried out in the same sequence, but offset in time by five time segments. This is configured so that as Reactor 1 comes to the end of its gasification step, Reactor 2 begins its gasification step, thereby ensuring that syngas production remains steady and continuous for the gas cleanup equipment and downstream users.

[0160] The above examples are merely examples of operational stages for two reactors, and it will be understood that the same principles may be applied to two or more gasifiers operating as a system. The actual time required for each operational stage will vary based on a number of factors. Thus, the number of time segments required for each stage may vary significantly. However, when considering two reactors, it is important that the gasification operation time be at least equal to or greater than the cumulative time required for loading, heating and purging, cooling and purging, purging with air, and unloading.

[0161] Where a prior art publication is referred to herein, it should be understood that such reference does not constitute an acknowledgement that the publication forms part of the common general knowledge in the art in Australia or any other country.

[0162] In the following claims and the foregoing description of the invention, unless the context requires otherwise by express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" are used in their inclusive sense, i.e., to specify the presence of stated features but not to exclude the presence or addition of further features in various embodiments of the invention.

[0163] Any promises made herein should be understood to relate to some embodiments of the invention and are not intended to be promises made with respect to the invention as a whole. If there are any promises that are deemed to apply to all embodiments of the invention, the applicant / patent owner reserves the right to subsequently delete them from the specification and will not rely on these promises for the grant or subsequent grant of a patent in any country.

Claims

1. 1. A method for producing gas from a combustible material, comprising the steps of: (a) filling a containment structure with the flammable material, the containment structure having a first side and a second side disposed along either side of an elongated axis; (b) substantially sealing the containment structure; and (c) supplying an oxidizer into the sealed containment structure via an oxidizer injection point to ignite the combustible material; (d) moving the oxidant injection point from one end of the containment structure to the other; (e) controlling the flow rate of oxidizer and the rate of movement of the oxidizer injection point such that the combustible material is partially converted, thereby leaving a thermally affected layer of combustible material within the sealed containment structure after the injection point has passed through the material; (f) cooling and purging the sealed containment structure; (g) opening the sealed containment structure and filling with new combustible material above the top thermally affected layer remaining after completion of steps (c) through (e); Including, In the method wherein during step (e) at least a portion of said combustible material is converted to molten slag and / or char which accumulates as the lowermost thermally affected layer and subsequently cools and solidifies, further comprising the steps of: draining solid slag and / or char in the lowermost thermally affected layer from lower material remaining in the containment structure to remove the solid slag and / or char from the containment structure; (h) repeating steps (a) to (g); The method of claim 1, further comprising:

2. 2. The method of claim 1, wherein the discharging step is performed by one or more rams operable to discharge solid slag or char by moving from the first side of the containment structure toward an openable / closable opening in the second side of the containment structure.

3. 3. The method of claim 1 or 2, wherein after step (b) and before step (c), there is a step of heating the combustible material with a heated gas to pre-dry the combustible material.

4. 4. The method of claim 2, or claim 3 when dependent on claim 2, wherein at least one of the one or more rams includes one or more openings for injecting the heating gas, purge gas and / or cooling gas, if present, into the containment structure.

5. The method of claim 4 , wherein the ram includes a front ram surface, a top surface and a bottom surface, and the one or more openings are disposed in the front ram surface.

6. 6. The method of any one of claims 1 to 5, wherein the combustible material is partially converted to char without forming slag.

7. The method of any one of claims 1 to 5, wherein the combustible material is converted into slag and char.

8. The following steps: collecting solid slag and / or char removed from the containment structure; Separating the solid slag from the char; adding the separated char together with the new combustible material recharged in step (g); 8. The method of claim 7, comprising:

9. A method according to any preceding claim, wherein there are two or more rams positioned along the elongate axis of the containment structure.

10. 10. The method of any one of claims 1 to 9, wherein there are two or more openable / closable openings in the second side of the containment structure, each opening being closeable by a trough door comprising a water seal.

11. The method according to any one of claims 1 to 10, wherein the combustible material is municipal waste.

12. The method according to any one of claims 1 to 11, wherein the heating gas, the cooling gas and / or the purge gas is nitrogen.

13. 13. The method of any one of claims 1 to 12, wherein the step of moving the oxidant injection point from one end of the structure to the other comprises retracting an injection member along an elongate axis of the containment structure.

14. 1. A containment structure for use as a gasifier having a bottom, a first side, and a second side disposed along either side of an elongated axis, comprising: To be filled with flammable materials, So that it can be sealed when filled with flammable materials. When sealed, the container is heated with a heating gas to pre-dry the combustible material. Operated during the production stage according to step (e) of claim 1, such that during step (e) at least a portion of the combustible material is converted into molten slag and / or char which accumulates as the lowermost thermally affected layer and subsequently cools and solidifies, one or more rams are movable from the first side of the containment structure to the second side of the containment structure; and One or more openable / closable openings in the second side of the containment structure for discharging solid slag and / or char from lower material remaining within the containment structure. A configured storage structure.

15. Char recovered from the containment structure of claim 14.

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