Power generation system and power generation method

Abstract

The present application relates to the field of power generation, and discloses a power generation system and a power generation method. The system comprises: a gasification unit configured to receive a carbonaceous feedstock stream and generate a syngas stream; a reaction unit in fluid communication with the gasification unit, configured to receive at least part of the syngas stream for an exothermic reaction to increase the temperature and hydrogen content of the syngas stream, and obtain a syngas stream with increased hydrogen content; a syngas stream storage unit in fluid communication with the gasification unit, configured to receive at least part of the syngas stream for storage; and a power generation unit in fluid communication with the reaction unit, configured to generate power using hydrogen in the syngas stream with increased hydrogen content. The present application can realize flexible peak shaving of an IGCC system.

Description

Technical Field

[0001] This invention relates to the field of power generation, and more specifically to a power generation system and a power generation method. Background Technology

[0002] Current thermal power technologies include conventional coal-fired power generation and Integrated Gasification Combined Cycle (IGCC) power generation. Conventional coal-fired power units typically reduce carbon emissions through post-combustion carbon capture, with chemical absorption being the mainstream technology. The advantage of this approach is that it achieves low carbon emissions without requiring significant modifications to existing coal-fired units. However, conventional coal-fired units can only achieve peak-shaving capacity of up to 15% of rated load, have insufficient rapid start-up and shutdown capabilities, and poor flexibility. IGCC integrates coal gasification and gas turbine combined cycle power generation technologies, representing a highly efficient and clean advanced coal-fired power technology. It offers advantages in efficiency and environmental protection (CO2, dust, NOx). x SO x While IGCC power plants offer significant advantages in terms of energy efficiency and water conservation, their response speed remains a bottleneck for flexible peak shaving. Existing IGCC power plants have a minimum operating load of 70% for their air separation and gasification furnace systems, and the long cold start time of the air separation unit makes them unsuitable for flexible peak shaving. Gas turbines offer rapid start-up and shutdown with high flexibility, but their operation is limited by syngas flow rate; significant fluctuations in flow not only affect the turbine's output power but also damage its lifespan. Steam turbines, similar to conventional coal-fired units, suffer from low flexibility due to their high structural rigidity and long start-up time. Therefore, improving the units within the IGCC system to enhance its flexibility is a pressing issue.

[0003] Existing high-efficiency, low-carbon IGCC systems (such as CN118620660A) only conceive of how to integrate carbon capture units with IGCC power generation systems, without considering which carbon capture technology can minimize system energy loss, nor innovate on the flexibility of carbon capture power generation systems.

[0004] Existing air energy storage solutions (such as CN206144670U) involve installing large-capacity liquid oxygen and liquid nitrogen storage tanks within the air separation system, along with dedicated oxygen and nitrogen heaters. Utilizing the energy storage capacity of the IGCC air separation system, it achieves rapid peak shaving for the IGCC power plant by directly reducing and increasing the plant's power consumption. While this technology improves the flexibility of the air separation system, it cannot specifically address the flexibility issue of the gasifier. Oxygen and nitrogen can be stored during low-load demand, but if the amount of gas entering the gasifier is insufficient, the gasifier temperature will be inadequate, hindering the effective production of syngas. This will also alter the hydrocarbon ratio, affecting the output power of the subsequent gas turbine and the efficiency of the waste heat boiler. Therefore, flexible peak shaving for the entire IGCC system is not achieved. Summary of the Invention

[0005] The purpose of this invention is to overcome the problem that existing IGCC systems cannot achieve flexible peak shaving, and to provide a power generation system and method that can achieve flexible peak shaving in IGCC systems.

[0006] This invention provides a system comprising:

[0007] A gasification unit configured to receive a carbonaceous feedstock stream and generate a synthesis gas stream;

[0008] A reaction unit in fluid communication with the gasification unit is configured to receive at least a portion of the syngas flow for an exothermic reaction to increase the temperature and hydrogen content of the syngas flow, thereby obtaining a syngas flow with increased hydrogen content.

[0009] A synthesis gas storage unit in fluid communication with the gasification unit is configured to receive at least a portion of the synthesis gas for storage.

[0010] A power generation unit, which is in fluid communication with the reaction unit, is configured to generate electricity using hydrogen in a synthesis gas stream with increased hydrogen content.

[0011] A second aspect of the present invention provides a method comprising the following steps:

[0012] S1. Introduce a carbonaceous feedstock stream into the gasification unit to generate a synthesis gas stream;

[0013] S2. Based on the power generation load, the syngas is fed into the reaction unit for an exothermic reaction to obtain a syngas stream with increased hydrogen content, and / or, the syngas is fed into the syngas stream storage unit to store the syngas stream.

[0014] S3. The power generation unit generates electricity using the synthetic gas stream with increased hydrogen content.

[0015] During their research, the inventors of this invention discovered that the fundamental reason why IGCC systems cannot achieve flexible peak shaving lies in their sluggish system response: load change signals from the power grid need to be transmitted and adjusted sequentially across multiple stages, including air separation for oxygen production, coal feeding into the gasifier, syngas flow, and gas turbine combustion. This lengthy process chain (air separation → gasification → purification → gas turbine power generation → waste heat boiler → steam turbine power generation) results in slow load fluctuations. Furthermore, the load variation capacity of air separation and gasification is poor, only reaching a minimum of 70-80%. This inherent response delay limits the application of IGCC in scenarios requiring rapid peak shaving. To address this problem, this invention stores a portion of the syngas, thereby circumventing the low flexibility of the air separation unit and gasifier system. Syngas can be stored for backup during off-peak periods and released to boost load during peak periods, thus achieving flexible peak shaving for power generation.

[0016] Furthermore, adsorption-based carbon capture technologies in IGCC systems are generally divided into pressure swing adsorption (PSA) and temperature swing adsorption (TSA). PSA fully utilizes the high-pressure characteristics of the gas for adsorption, followed by depressurization and desorption, effectively utilizing the kinetic energy of the gas with low energy consumption. However, current industrial applications commonly use ambient temperature PSA, which still requires lowering the gas temperature to below 40 degrees Celsius, followed by reheating after adsorption, resulting in insufficient energy utilization. Temperature swing adsorption requires temperature changes for CO2 adsorption and desorption, leading to relatively high energy loss for the high-temperature, high-pressure gas characteristics in the system. To address this issue, the preferred embodiment of this invention utilizes the medium-temperature, high-pressure characteristics of syngas, employing medium-temperature PSA to perform CO2 adsorption and depressurization desorption without changing the gas temperature, thus achieving CO2 capture and fully utilizing the energy of the syngas. This avoids the high energy consumption and significant energy loss problems of traditional carbon capture technologies. Therefore, this invention achieves low carbon emissions and flexible peak shaving in IGCC systems.

[0017] In a preferred embodiment, the present invention stores a portion of the syngas exiting the gasification unit, performs water-gas shift conversion and then decarbonizes the remaining syngas, and then uses the converted hydrogen to generate electricity in a hydrogen-rich gas turbine, followed by a combined cycle of steam turbine power generation. This method effectively solves the mutual constraint between decarbonization and pure hydrogen storage, ensuring both syngas storage and compliance with carbon emission standards. Attached Figure Description

[0018] Figure 1 This is a flowchart illustrating a specific embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures

[0020] Detailed Implementation

[0021] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] The description of exemplary embodiments is intended to be read in conjunction with the accompanying drawings, which are considered an integral part of the entire written description. In this specification, related terms such as “down,” “up,” “horizontal,” “vertical,” “above,” “below,” “upward,” “downward,” “top,” and “bottom,” and their derivatives (e.g., “horizontally,” “downward,” “upward,” etc.) should be interpreted as referring to directions as described subsequently or as shown in the drawings discussed. These related terms are for ease of description and do not require the device to be constructed or operated in a particular orientation. Unless otherwise expressly stated, terms relating to connection, linkage, etc., such as “connection” and “interconnection,” refer to a relationship in which structures are directly or indirectly fixed or connected to each other through intermediate structures, and to movable or rigid connections or relationships.

[0023] For the purposes described below, it should be understood that alternative variations and implementations may be taken of the embodiments described below. It should also be understood that the specific products, compositions, and / or methods described herein are exemplary and should not be considered limiting.

[0024] In this invention, when a value is expressed as an approximation using the antecedent “about,” it should be understood that a particular value forms another embodiment. As used herein, “about X” (where X is a numerical value) preferably refers to ±10% of the referenced value, including endpoint values. For example, the phrase “about 8” preferably refers to a value in the range of 7.2 to 8.8 (inclusive of endpoint values ​​7.2 and 8.8). When present, all ranges are inclusive and composable. For example, when listing a range of “1 to 5,” the listed range should be interpreted as including ranges “1 to 4,” “1 to 3,” “1-2 and 4-5,” “1-3 and 5,” “2-5,” etc.

[0025] Unless otherwise explicitly stated, the terms “substantially” and “substantially the same” as used herein shall be understood to cover parameters that fluctuate within a suitable range, such as ±10% or ±15% fluctuation of the parameter. In some implementations, the fluctuation range is within ±10%.

[0026] As used herein, when an element or component is described as forming a “connection,” “link,” “connection,” or “contact” with another element or component, that element or component may be directly connected to, directly linked to, or directly contact the particular element or component, or may be connected, linked to, or contacted with the particular element or component through an intermediate element or component. When an element or component is described as “directly connected,” “directly linked,” “directly connected,” or “directly contacting” another element, there is no intermediate element or component.

[0027] As used herein, the terms “fluidly connected to” or “fluidly coupled” or “fluidly connected” as used herein will be understood as a component being connected to a pipe or line and configured to allow gas or liquid to flow through the component.

[0028] The terms “ambient temperature” and “room temperature” used in this article will be understood as the temperature under ambient conditions, such as a room temperature of 20-22°C.

[0029] This invention provides a system, such as Figure 1 As shown, it includes:

[0030] Gasification unit 2, the gasification unit being configured to receive a carbonaceous feedstock stream and generate a synthesis gas stream;

[0031] A reaction unit in fluid communication with the gasification unit is configured to receive at least a portion of the syngas flow for an exothermic reaction to increase the temperature and hydrogen content of the syngas flow, thereby obtaining a syngas flow with increased hydrogen content.

[0032] A synthesis gas storage unit in fluid communication with the gasification unit is configured to receive at least a portion of the synthesis gas for storage.

[0033] A power generation unit, which is in fluid communication with the reaction unit, is configured to generate electricity using hydrogen in a synthesis gas stream with increased hydrogen content.

[0034] This invention does not impose any particular limitation on the specific arrangement of the gasification unit, as long as it can produce a synthesis gas stream from carbonaceous raw materials. Preferably, the gasification unit includes a gasifier.

[0035] According to a preferred embodiment of the present invention, the gasification unit is provided with a carbonaceous feedstock receiving port.

[0036] According to one specific embodiment of the present invention, the gasification unit is fluidly connected to the carbonaceous raw material supply unit.

[0037] The carbonaceous raw materials described in this invention include, but are not limited to, coal, natural gas, and biomass.

[0038] In order to produce a synthesis gas stream from carbonaceous raw materials, the gasifier is also equipped with a steam inlet and an oxygen inlet.

[0039] The present invention does not particularly limit the source of oxygen. Preferably, the system further includes an air separation unit 1 in fluid communication with the gasification unit, the air separation unit being configured to separate air into oxygen and nitrogen to provide the oxygen required by the gasification unit.

[0040] Preferably, the system further includes a liquid oxygen storage tank 12 in fluid communication with the air separation unit, the liquid oxygen storage tank being configured to receive oxygen from the air separation unit and supply it to the gasification unit when needed.

[0041] According to a preferred embodiment of the present invention, the air separation unit is equipped with an adjustable-speed air compressor and a distillation column. The air compressor provides cooling air to the distillation column. Inside the distillation column, the air is separated into liquid nitrogen and liquid oxygen (a portion of which can be stored in a dedicated liquid nitrogen storage tank and a liquid oxygen storage tank, respectively). The air flows through a cold box that recovers cold energy for heat exchange, and then is heated and vaporized by an oxygen heater to finally produce high-pressure oxygen that is delivered to the gasification furnace for use.

[0042] In this invention, the gasifier load can be adjusted according to the power generation load regulation requirements. Because the load regulation capability of the cryogenic air separation unit is relatively low, if the gasifier load is low, excess oxygen can be stored in a liquid oxygen storage tank and used in the gasifier when the load is high.

[0043] In this invention, oxygen, water vapor and carbonaceous raw materials (such as pulverized coal) undergo a gasification reaction in a gasifier to produce crude coal gas containing CO, H2, CO2, H2O, H2S and dust, etc., and ash is discharged from the bottom of the gasifier.

[0044] Preferably, the system of the present invention is further provided with a purification unit that flows in fluid with the gasification unit, the purification unit being configured to receive the effluent stream (e.g., crude coal gas) from the gasification unit and purify it.

[0045] This invention does not impose any particular limitation on the specific configuration of the purification unit, and it can be configured according to conventional methods in the art. Preferably, the purification unit includes a syngas cooler 13, a dust removal unit 14, and a desulfurization unit 15 connected in series. Specifically, the crude coal gas enters the purification unit after being cooled by cooling water, and the steam generated by the cooling water can be sent to a steam turbine for power generation. In the purification unit, the crude coal gas is first sprayed and washed in a dust removal unit (e.g., a spray tower) to remove dust, and then washed before entering a desulfurization unit (e.g., a desulfurization tower) to remove sulfuric acid-containing gases such as H2S. The removed H2S is then oxidized to produce sulfur, which can be sold separately.

[0046] According to a preferred embodiment of the present invention, a syngas compressor 6 is provided between the gasification unit and the syngas storage unit, which is configured to compress at least a portion of the syngas and then store it in the syngas storage unit.

[0047] The present invention does not impose any particular limitations on the synthetic gas flow compressor, and the compressor can be selected according to the specific process conditions. For example, it can be a large industrial wide-load compressor, preferably a twin-cylinder gear speed-increasing centrifugal compressor or an axial flow compressor.

[0048] According to the present invention, the syngas is preferably purified and divided into two streams. One stream is connected to a syngas compressor, which compresses a portion of the syngas into a storage tank for storage (diverted according to the power generation load). The other stream is connected to a reaction unit, where the syngas undergoes an exothermic reaction to obtain a syngas stream with increased hydrogen content. The syngas stream with increased hydrogen content is then used to generate electricity in a power generation unit.

[0049] According to the present invention, preferably, the syngas storage unit includes a syngas storage tank 4. The present invention does not impose any particular limitation on the syngas storage tank, and it can be selected according to specific process conditions. Preferably, the syngas storage tank is selected from at least one of horizontal cylindrical tanks, vertical cylindrical tanks, and spherical tanks.

[0050] According to the present invention, preferably, the system further includes a heat storage unit 7, which is configured to collect heat from the system and transfer the collected heat to units within the system that require heating. This preferred embodiment is more conducive to energy conservation.

[0051] Preferably, the heat storage unit is configured to collect heat generated by the syngas compressor and / or heat released by the reaction unit. The syngas compressor outlet gas temperature is high, allowing for efficient utilization of sensible heat. The reaction process (preferably water-gas shift reaction) is exothermic, and the heat in the reactor can be recovered and reused.

[0052] Preferably, the heat storage unit is configured to collect heat generated during the washing process of the dust removal unit. The saturated water vapor after dust removal and washing has significant latent heat utilization value.

[0053] The present invention does not impose any particular limitation on the heat storage unit, and it can be any kind of heat storage device commonly used in the art, such as a heat storage tank.

[0054] The aforementioned syngas storage refers to the process of compressing purified syngas to high pressure using a motor-driven or steam-driven compressor, and then storing it in a syngas storage tank. This compression process generates a significant amount of heat, which is stored in a thermal storage tank. During the syngas release phase, the syngas is heated using the heat stored in the thermal storage tank or steam, and then an expander drives a generator to produce electricity. This process not only completes the storage of syngas but also enables energy storage using syngas, achieving both flexible peak-shaving for the IGCC power generation system and efficient energy utilization.

[0055] According to the present invention, preferably, the system further includes a waste heat recovery unit 8 and a steam turbine 9 in fluid communication with the power generation unit; the waste heat recovery unit is configured to receive exhaust gas from the power generation unit to recover waste heat and generate steam; the steam turbine is configured to receive steam from the waste heat recovery unit to generate electricity. The specific configuration of the waste heat recovery unit (e.g., a waste heat boiler) and the steam turbine can be found in conventional techniques in the art, and the present invention does not impose any particular limitations on them.

[0056] Preferably, the waste heat recovery unit is configured to communicate with the heat storage unit to transfer at least a portion of the heat collected by the heat storage unit to the waste heat recovery unit. The heat collected by the heat storage unit can be selectively sent to a waste heat boiler to improve the efficiency of the waste heat boiler.

[0057] According to a preferred embodiment of the present invention, a carbon dioxide pressure swing adsorption unit 10 is provided between the reaction unit and the power generation unit. The carbon dioxide pressure swing adsorption unit is configured to change the adsorption of carbon dioxide in a syngas stream with increased hydrogen content to obtain a syngas stream with reduced carbon dioxide content. The captured CO2 can be compressed, liquefied, and stored by a CO2 compressor 16, and then transported.

[0058] Preferably, the carbon dioxide pressure swing adsorption unit is configured to perform carbon dioxide pressure swing adsorption under mesophilic conditions. More preferably, the mesophilic conditions are conditions within the temperature range of 100-350℃. By utilizing the mesophilic and high-pressure characteristics of syngas, a mesophilic pressure swing adsorbent is used to perform CO2 adsorption and depressurization desorption without changing the gas temperature, thereby achieving CO2 capture. This fully utilizes the energy of the syngas and avoids the problems of high energy consumption and large energy loss in traditional carbon capture technologies.

[0059] Preferably, the carbon dioxide pressure swing adsorption unit includes a group of multiple towers controlled by time sequence, which simultaneously perform adsorption, pressure equalization, desorption and reverse release operations, thereby rotating each single tower to perform different steps in turn.

[0060] Preferably, the carbon dioxide pressure swing adsorption (PSA) unit is configured to communicate with the thermal storage unit to transfer at least a portion of the heat collected by the thermal storage unit to the PSA unit. The heat collected by the thermal storage unit can be introduced into the desorption tower within the PSA unit to increase the desorption rate, promote desorption and regeneration, and reduce energy consumption. The injection of heat into the adsorption tower can be achieved through an internal heat exchanger within the desorption tower, via heat exchange through the flow of the thermal storage medium.

[0061] According to the present invention, preferably, the system further includes an expander 11 in fluid communication with the synthetic gas storage unit, the expander being configured to receive synthetic gas released from the synthetic gas storage unit for power generation.

[0062] Preferably, the outlet of the expander is in fluid communication with the inlet of the reaction unit so as to send the syngas generated by the expander to the reaction unit.

[0063] Preferably, the expander is configured to communicate with the thermal storage unit to transfer at least a portion of the heat collected by the thermal storage unit to the expander to heat the syngas used for power generation by the expander. The heat transferred from the thermal storage unit can be used to heat the syngas released from the syngas gas storage unit, causing it to expand and perform work.

[0064] According to the present invention, preferably, the reaction unit is a water-gas shift reaction unit 3. In this preferred embodiment, CO in the synthesis gas can be converted into CO2, H2O into H2, and then CO2 is removed by a carbon dioxide pressure swing adsorption unit, while H2 enters the power generation unit to generate electricity.

[0065] The present invention does not particularly limit the power generation unit, and it can be any type of power generation unit conventional in the art. For example, it can be a gas turbine 5. H2 enters the gas turbine combustion chamber for combustion and power generation.

[0066] It should be noted that, in the system provided by the present invention, in a preferred embodiment, the maximum load capacity of the air separation unit, the gasification system, and the gas turbine is designed to be within 120% of their rated power.

[0067] A second aspect of the present invention provides a method comprising the following steps:

[0068] S1. Introduce a carbonaceous feedstock stream into the gasification unit to generate a synthesis gas stream;

[0069] S2. Based on the power generation load, the syngas is fed into the reaction unit for an exothermic reaction to obtain a syngas stream with increased hydrogen content, and / or, the syngas is fed into the syngas stream storage unit to store the syngas stream.

[0070] S3. The power generation unit generates electricity using the synthetic gas stream with increased hydrogen content.

[0071] According to a preferred embodiment of the present invention, the method is performed in the above-described system.

[0072] According to the present invention, preferably, the amount of syngas undergoing the exothermic reaction and being stored is adjusted according to the power generation load to meet the power load requirements.

[0073] Preferably, when there is no demand for electricity, the air separation unit and gasification unit in the power generation system operate at minimum load, and all the generated syngas flows into the syngas storage unit for storage. At this time, other units (reaction unit, carbon dioxide adsorption unit, power generation unit, waste heat recovery unit, steam turbine) are preferably shut down.

[0074] This invention does not impose a specific limit on the minimum load value, which can be selected based on the specific conditions of the air separation unit and the gasification unit in the generator set. Preferably, when there is no electricity demand, the air separation unit and the gasification unit in the power generation system maintain 70-80% load operation. Currently, the minimum load for domestic IGCC air separation units is approximately 80%, and for gasification units, it is approximately 75%. The minimum load described in this invention can be changed with technological updates to the air separation unit and the gasification unit.

[0075] According to the present invention, preferably, when the electricity demand is less than 80% of the rated load capacity of the power generation system, a portion of the syngas is fed into the reaction unit for an exothermic reaction according to the electricity demand. The resulting syngas gas with increased hydrogen content is used for power generation, and the amount of syngas used is sufficient to meet the electricity load. The remaining syngas is fed into the syngas gas storage unit.

[0076] Preferably, when IGCC low-load power generation and peak shaving are required, the air separation unit and gasification unit operate at low load. According to the required power generation load, a portion of the syngas is purified, steam-water conversion and carbon dioxide adsorption unit and then enters the power generation unit for combustion and power generation. The exhaust gas from the gas turbine is sent to the waste heat boiler to recover the waste heat of the exhaust gas and generate steam, which is sent to the steam turbine for power generation. If there is any syngas remaining, another portion of the syngas is purified and then stored in the storage tank.

[0077] According to the present invention, preferably, when the electricity demand is greater than or equal to 80% and less than or equal to 120% of the rated load capacity of the power generation system, the air separation unit and gasification unit in the power generation system maintain the minimum load, preferably 70-80%, to generate electricity from the syngas with increased hydrogen content, and to generate electricity using the syngas released from at least a portion of the syngas storage unit to meet the electricity demand.

[0078] According to the present invention, preferably, when the IGCC requires high-load or full-load operation, the air separation unit and gasification unit initially maintain low-load operation. The newly generated syngas is mixed with the partially released syngas in the syngas gas storage unit after passing through the purification unit, and then enters the reaction unit, the carbon dioxide adsorption unit, and finally the power generation unit for power generation. The exhaust gas from the gas turbine is sent to the waste heat boiler to recover the waste heat from the exhaust gas and generate steam, which is then sent to the steam turbine for power generation. The captured CO2 is compressed and liquefied before storage or transportation.

[0079] Preferably, when the syngas stored in the syngas storage unit is about to be exhausted, preferably less than 10% by volume, the load of the air separation unit and the gasification unit is increased according to the power demand, preferably operating at full load (or overload).

[0080] According to the method of the present invention, preferably, the load capacity of the air separation unit and the gasification unit is adjusted according to the maximum load of the power generation unit, and more preferably, the variable load capacity of the air separation unit is designed to be 80%-120%.

[0081] According to the present invention, preferably, the method includes collecting heat from the system using a heat storage unit and transferring the collected heat to a unit within the system that requires heating; more preferably, the heat from the system includes heat generated by storing compressed synthesis gas streams and / or heat released by the reaction unit.

[0082] According to the present invention, preferably, the heat from the system also includes the heat generated during the washing process of the dust removal unit.

[0083] According to the present invention, preferably, the method includes generating electricity using the syngas released by the syngas storage unit through an expander; more preferably, the method further includes sending the syngas generated by the expander to a reaction unit.

[0084] According to the present invention, preferably, the reaction unit is a water vapor shift reaction unit.

[0085] According to the present invention, preferably, the method further includes subjecting the synthesis gas stream with increased hydrogen content to pressure swing adsorption of carbon dioxide to obtain a synthesis gas stream with reduced carbon dioxide content, and using the synthesis gas stream with reduced carbon dioxide content for power generation.

[0086] According to the present invention, preferably, the carbon dioxide pressure swing adsorption is carried out under mesophilic conditions, wherein the mesophilic conditions are conditions with a temperature range of 100-350°C.

[0087] This invention does not impose any particular limitation on the pressure setting during the carbon dioxide pressure swing adsorption process. Those skilled in the art can make adaptive selections based on the selected adsorbent and complete the adsorption and desorption of carbon dioxide according to the principle of high-pressure adsorption and low-pressure desorption.

[0088] According to the present invention, preferably, the method further includes using an air separation unit to separate air to obtain oxygen and nitrogen, and providing the oxygen to a vaporization unit; more preferably, the method includes storing the oxygen from the air separation unit in a liquid oxygen storage tank and providing it to the vaporization unit when needed.

[0089] It should be noted that the specific operations and preferred methods of each step in the method provided by this invention can be understood by referring to the system described in the first aspect. Further details of this invention will not be repeated here.

[0090] The present invention will be described in detail below through embodiments.

[0091] Example 1

[0092] An example is described for an IGCC unit with an annual power generation load of 250MW.

[0093] The system uses a cryogenic air separation distillation unit to produce nitrogen and oxygen. The oxygen is sent to a gasifier, which is a Huaneng two-stage dry pulverized coal pressurized gasifier, operating at 1400... o Dry pulverized coal is gasified at high temperature (C) and high pressure (30 bar) to produce syngas, which mainly consists of carbon monoxide and hydrogen. The effective syngas yield is approximately 110,000 Nm³. 3 / h. The crude syngas is cooled down using a cooling spray, at which point the temperature of the crude syngas drops to 300. o C, pressure 28 bar. The high-pressure steam generated during the spraying process is sent to a steam turbine for power generation. Further spraying and cooling of the syngas is used for dust removal and washing, while a heat storage medium is used to recover waste heat from the dust removal process. At this point, the temperature of the crude syngas drops to 150°C. o C, pressure 27 bar. After heat exchange optimization, the synthesis gas temperature dropped to 40°C. o C, and then the hydrogen sulfide in the synthesis gas is oxidized to remove sulfur, while the pressure remains unchanged.

[0094] Syngas is distributed according to the power demand of the grid through a flow distribution valve. A portion of the syngas is compressed under high pressure using a centrifugal compressor and pumped to a syngas storage tank. When syngas needs to be released, it generates electricity via a turbine expander. The syngas, cooled by expansion, is reheated by a thermal storage system. The released syngas then enters a water-gas shift unit. In this embodiment, the IGCC zero-load shutdown peak-shaving time is set to 10:00-14:00 daily for 4 hours, requiring the storage of approximately 400,000 Nm³ of syngas. 3 / h. Syngas storage tank conditions are set at 100 bar, 40 o C, at this storage pressure, the required tank volume is approximately 4400 m³. 3 The volume of a single storage tank is designed to be 160m³. 3 Multiple horizontal high-pressure storage tanks are connected in series to store syngas.

[0095] Another stream of syngas directly enters the steam shift unit to convert CO into CO2 and H2. The outlet gas temperature of the steam shift unit is approximately 300°C. o At temperature C, pressure approximately 27 bar, the main components are CO2 and H2. The shifted gas is introduced into an adsorption unit consisting of eight towers connected in series. The adsorbent is an alkaline earth metal carbonate, capable of withstanding temperatures up to 300°C. o C. Medium temperature. The decarbonized hydrogen-rich fuel gas is fed into an E-class hydrogen-rich gas turbine for combustion and power generation. The resulting exhaust gas is used to generate steam through a waste heat boiler, which then drives a steam turbine to generate electricity, achieving a low-carbon integrated combined cycle of coal gasification.

[0096] Peak shaving process: The air separation and gasification systems operate at 100% full load. Syngas directly enters the water-gas shift converter, pressure swing adsorption (PSA), and gas turbine power generation units sequentially. After 9:00 AM daily, the load of the air separation and gasification systems is adjusted to 80% at a rate of 0.33% / min. After 10:00 AM daily, the PSA, PSA, and gas turbine power generation units are shut down sequentially, and the syngas produced by gasification is stored in a high-pressure syngas storage tank. After 2:00 PM, the electricity demand is at 100% rated load of the generator sets. The air separation and gasification systems continue to operate at 80% load. The produced syngas mixes with a portion of the syngas released from the storage tank and sequentially enters the PSA, PSA, and gas turbine power generation units. After 6:00 PM, the capacity of the air separation and gasification furnaces is increased to 100% full load. By 7:00 PM, there is no gas left in the syngas storage tank, and the entire system operates at 100% full load, thus completing the peak shaving task.

[0097] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for generating electricity, characterized in that, The method includes the following steps: S1. Introduce a carbonaceous feedstock stream into the gasification unit to generate a synthesis gas stream; S2. Based on the power generation load, the syngas is fed into the reaction unit for an exothermic reaction to obtain a syngas stream with increased hydrogen content, and / or, the syngas is fed into the syngas stream storage unit to store the syngas stream. S3. The power generation unit generates electricity using the synthetic gas stream with increased hydrogen content; The amount of syngas used for exothermic reactions and storage is adjusted according to the power generation load to meet the power load requirements. When there is no demand for electricity, the air separation unit and gasification unit in the power generation system operate at the minimum load, and all the syngas produced flows into the syngas storage unit for storage. When the electricity demand is less than 80% of the rated load capacity of the power generation system, a portion of the syngas is fed into the reaction unit for an exothermic reaction according to the electricity demand. The resulting syngas gas with increased hydrogen content is used for power generation. The amount of syngas used is sufficient to meet the electricity load. The remaining syngas is fed into the syngas gas storage unit. When the electricity demand is greater than or equal to 80% and less than or equal to 120% of the rated load capacity of the power generation system, the air separation unit and gasification unit in the power generation system maintain a load of 70-80% to generate electricity from the syngas with increased hydrogen content, and also utilize the syngas released from at least part of the syngas storage unit to generate electricity to meet the electricity demand.

2. The method according to claim 1, wherein, When the syngas stored in the syngas storage unit is less than 10% by volume, the load of the air separation unit and the gasification unit will be increased according to the power demand.

3. The method according to claim 1, wherein, The method involves using a thermal storage unit to collect heat from the system and transferring the collected heat to units within the system that require heating.

4. The method according to claim 3, wherein, The heat from the system includes the heat generated during the storage of the compressed synthesis gas stream and / or the heat released by the reaction unit.

5. The method according to claim 1, wherein, The method includes generating electricity using the syngas released from the syngas storage unit via an expander; The method also includes sending the fuel gas generated by the expander to the reaction unit.

6. The method according to claim 1, wherein, The reaction unit is a water-vapor shift reaction unit.

7. The method according to claim 1, wherein, The method also includes subjecting a synthesis gas stream with increased hydrogen content to pressure swing adsorption (PSA) to obtain a synthesis gas stream with reduced carbon dioxide content, and then using the synthesis gas stream with reduced carbon dioxide content for power generation.

8. The method according to claim 7, wherein, The carbon dioxide pressure swing adsorption is carried out under mesophilic conditions, which are conditions with a temperature range of 100-350℃.

9. The method according to claim 1, wherein, The method also includes using an air separation unit to separate air into oxygen and nitrogen, and supplying the oxygen to a gasification unit.

10. The method according to claim 9, wherein, The method involves storing oxygen from the air separation unit in a liquid oxygen tank and supplying it to the gasification unit when needed.

11. The method according to claim 1, wherein, When there is no demand for electricity, the air separation unit and gasification unit in the power generation system operate at 70-80% load, and all the generated syngas flows into the syngas storage unit for storage.

12. The method according to any one of claims 1-11, wherein, The method is performed in a system comprising: A gasification unit configured to receive a carbonaceous feedstock stream and generate a synthesis gas stream; A reaction unit in fluid communication with the gasification unit is configured to receive at least a portion of the syngas flow for an exothermic reaction to increase the temperature and hydrogen content of the syngas flow, thereby obtaining a syngas flow with increased hydrogen content. A synthesis gas storage unit in fluid communication with the gasification unit is configured to receive at least a portion of the synthesis gas for storage. A power generation unit, which is in fluid communication with the reaction unit, is configured to generate electricity using hydrogen in a synthesis gas stream with increased hydrogen content.

13. The method according to claim 12, wherein, A syngas compressor is provided between the gasification unit and the syngas storage unit, which is configured to compress at least a portion of the syngas and then store it in the syngas storage unit.

14. The method according to claim 13, wherein, The system also includes a heat storage unit configured to collect heat from the system and transfer the collected heat to units within the system that require heating.

15. The method according to claim 14, wherein, The system also includes a waste heat recovery unit and a steam turbine in fluid communication with the power generation unit; the waste heat recovery unit is configured to receive exhaust gas from the power generation unit to recover waste heat and generate steam; the steam turbine is configured to receive steam from the waste heat recovery unit to generate electricity.

16. The method according to claim 15, wherein, The waste heat recovery unit is configured to communicate with the heat storage unit to transfer at least a portion of the heat collected by the heat storage unit to the waste heat recovery unit.

17. The method of claim 14, wherein, A carbon dioxide pressure swing adsorption unit is provided between the reaction unit and the power generation unit. The carbon dioxide pressure swing adsorption unit is configured to change the adsorption of carbon dioxide in the synthesis gas stream with increased hydrogen content to obtain a synthesis gas stream with reduced carbon dioxide content.

18. The method according to claim 17, wherein, The carbon dioxide pressure swing adsorption unit is configured to perform carbon dioxide pressure swing adsorption under mesotemperature conditions, wherein the mesotemperature conditions are conditions with a temperature range of 100-350°C.

19. The method according to claim 17, wherein, The carbon dioxide pressure swing adsorption unit is configured to communicate with the thermal storage unit to transfer at least a portion of the heat collected by the thermal storage unit to the carbon dioxide pressure swing adsorption unit.

20. The method according to claim 12, wherein, The system also includes an expander in fluid communication with the synthesis gas storage unit, the expander being configured to receive the synthesis gas released by the synthesis gas storage unit for power generation; The outlet of the expander is in fluid communication with the inlet of the reaction unit so as to send the syngas generated by the expander to the reaction unit.

21. The method according to claim 12, wherein, The system also includes an air separation unit in fluid communication with the vaporization unit, the air separation unit being configured to separate air into oxygen and nitrogen to provide the oxygen required by the vaporization unit.

22. The method according to claim 13, wherein, The system also includes a liquid oxygen storage tank in fluid communication with the air separation unit, the liquid oxygen storage tank being configured to receive oxygen from the air separation unit and supply it to the vaporization unit when needed.

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