Biomass gasification system

Abstract

The invention provides a biomass gasification system, which belongs to the field of biomass gasification and comprises a drying reactor, a pyrolysis reactor, a gasification reactor and a mixer, the drying reactor, the pyrolysis reactor and the gasification reactor are communicated in sequence, and an outlet of the mixer is communicated with an inlet of the gasification reactor; an inlet of the heat exchanger assembly is communicated with an outlet of the gasification reactor, and an outlet of the heat exchanger assembly is respectively communicated with an inlet of the drying reactor and an inlet of the mixer; biomass to be gasified is sequentially subjected to drying of the drying reactor, pyrolysis of the pyrolysis reactor and gasification treatment of the gasification reactor, solid is converted into gasified gas, the gasified gas enters the heat exchanger assembly to heat nitrogen and water in the heat exchanger assembly, and the heated nitrogen enters the drying reactor to be used for drying the biomass to be gasified. The heated water becomes water vapor, the water vapor enters the mixer to be mixed with air to form a gasifying agent, and the gasifying agent enters the gasification reactor to participate in gasification reaction. The gasification system can improve the utilization rate of energy in the gasification process.

Description

Technical Field

[0001] The invention belongs to the field of biomass gasification, and in particular relates to a biomass gasification system. Background Art

[0002] Biomass gasification is the process of converting solid biomass into gas fuel through multiple thermochemical reactions such as pyrolysis, oxidation, reduction and transformation. By simulating the biomass gasification process, relevant data such as material conversion rate and gas yield can be obtained without experimental operation, providing strong support for the improvement and optimization of gasification processes in industry.

[0003] At present, the biomass gasification system is mainly composed of a drying reactor, a pyrolysis reactor, a mixer, a gasification reactor and a combustion reactor. It should be understood that after the biomass is pyrolyzed and gasified, the generated gasification gas contains a large amount of heat, but in the existing gasification system, this heat is not fully utilized but wasted.

[0004] Therefore, how to improve the energy utilization rate of the gasification system becomes a problem to be solved. Summary of the invention

[0005] In order to solve the problem of low energy utilization rate of the existing gasification system, the present invention provides a biomass gasification system.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A biomass gasification system comprises a drying reactor, a pyrolysis reactor and a gasification reactor which are connected in sequence, and

[0008] a mixer, the outlet of which is in communication with the inlet of the gasification reactor;

[0009] a heat exchanger assembly, the inlet of which is in communication with the outlet of the gasification reactor, and the outlet of which is in communication with the inlet of the drying reactor and the inlet of the mixer respectively;

[0010] The biomass to be gasified is successively dried in a drying reactor, pyrolyzed in a pyrolysis reactor, and gasified in a gasification reactor, and is converted from a solid into a gasified gas. The gasified gas enters the heat exchanger assembly to heat the nitrogen and water in the heat exchanger assembly. The heated nitrogen enters the drying reactor to dry the biomass to be gasified. The heated water becomes water vapor. The water vapor enters the mixer and mixes with air to form a gasifying agent. The gasifying agent enters the gasification reactor to participate in the gasification reaction.

[0011] Preferably, the heat exchanger assembly comprises a first heat exchanger and a second heat exchanger:

[0012] The inlet of the first heat exchanger is communicated with the outlet of the gasification reactor, and the outlet of the first heat exchanger is communicated with the drying reactor;

[0013] The inlet of the second heat exchanger is in communication with the outlet of the first heat exchanger;

[0014] The gasified gas enters the first heat exchanger from the outlet of the gasification reactor to heat nitrogen, and enters the second heat exchanger to heat water to obtain water vapor.

[0015] Preferably, the heat exchanger assembly comprises a first heat exchanger and a second heat exchanger:

[0016] The inlet of the first heat exchanger is communicated with the outlet of the gasification reactor, and the outlet of the first heat exchanger is communicated with the drying reactor;

[0017] The inlet of the second heat exchanger is in communication with the outlet of the first heat exchanger;

[0018] The gasified gas enters the first heat exchanger from the outlet of the gasification reactor to heat nitrogen, and enters the second heat exchanger to heat water to obtain water vapor.

[0019] Preferably, it also includes:

[0020] The combustion reactor has an inlet connected to the outlet of the second heat exchanger and is used for burning the gasification gas.

[0021] Preferably, it also includes:

[0022] a condenser, the inlet of which is connected to the outlet of the second heat exchanger, the condenser being used to cool water vapor carried in the vaporized gas;

[0023] The first separator has an inlet connected to the outlet of the condenser and an outlet connected to the inlet of the combustion reactor. The first separator is used to separate the cooled water vapor.

[0024] Preferably, it also includes:

[0025] The inlet of the second separator is communicated with the outlet of the gasification reactor, and the outlet of the second separator is communicated with the inlet of the first heat exchanger. The second separator is used to separate ash from the gasification gas.

[0026] Preferably, it also includes:

[0027] The inlet of the third separator is connected to the outlet of the drying reactor, and the outlet is connected to the inlet of the pyrolysis reactor. The third separator is used to separate nitrogen and moisture carried in the biomass to be gasified.

[0028] Preferably, it also includes:

[0029] The fourth separator has an inlet connected to the outlet of the pyrolysis reactor and an outlet connected to the inlet of the gasification reactor. The fourth separator is used to separate tar produced after pyrolysis of the biomass to be gasified.

[0030] The biomass gasification system provided by the present invention has the following beneficial effects:

[0031] By adding a heat exchanger assembly and passing the vaporized gas into the heat exchanger assembly, the nitrogen can be heated, thereby improving the drying efficiency; it can provide energy for water, heating the water to become water vapor as the main component of the gasifier; and the energy utilization rate of the gasification system can be improved from the above two aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiment of the present invention and its design scheme, the following briefly introduces the drawings required for this embodiment. The drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0033] Figure 1 A schematic diagram of the structure of an existing biomass gasification system provided in an embodiment of the present application;

[0034] Figure 2 A schematic structural diagram of an improved biomass gasification system provided in an embodiment of the present application;

[0035] Figure 3 A schematic diagram of a structure in which a first heat exchanger and a second heat exchanger are connected according to an embodiment of the present application;

[0036] Figure 4 A schematic diagram of another structure of a first heat exchanger and a second heat exchanger connected to each other provided in an embodiment of the present application;

[0037] Figure 5 A schematic structural diagram of another improved biomass gasification system provided in an embodiment of the present application;

[0038] Figure 6 A schematic diagram of a pyrolysis reaction process provided in an embodiment of the present application;

[0039] Figure 7 A schematic diagram of the change of CO content with temperature provided in an embodiment of the present application;

[0040] Figure 8 A schematic diagram of the change of H2 content with temperature provided in an embodiment of the present application;

[0041] Fig. 9 A schematic diagram of the variation of CH4 content with temperature provided in an embodiment of the present application;

[0042] Fig.10 Schematic diagram of the before and after comparison of various gas contents of the original device and the improved device at 650°C;

[0043] Fig.11 A schematic diagram of nitrogen and water changing with temperature provided in an embodiment of the present application. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the technical solution of the present invention and implement it, the present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the scope of protection of the present invention.

[0045] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the technical solutions of the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0046] In addition, the terms "first", "second", etc. are used for descriptive purposes only and are not to be understood as indicating or implying relative importance. In the description of the present invention, it should be noted that, unless otherwise clearly specified or limited, the terms "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances. In the description of the present invention, unless otherwise specified, "plurality" means two or more, which will not be described in detail here.

[0047] Before introducing the embodiments of the present invention, the relevant background of the present invention is first described.

[0048] Biomass gasification technology is a thermochemical treatment technology that has developed rapidly in recent years. It is the most effective, promising and valuable technology and application method for high-quality and efficient utilization of biomass energy. Biomass thermochemical hydrogen production is a thermochemical conversion technology that converts biomass into a synthesis gas composed of H2, CO and CH4. Gasification is a process in which solid or liquid fuels are converted into combustible gas products using a gasifying agent at high temperature to generate combustible gas, and solid biomass is converted into gas fuel through multiple thermochemical reactions such as pyrolysis, oxidation, reduction and transformation. Gasified coal gas mainly contains combustible gases CO, H2, CH4, CO2 and N2. Direct combustion of straw will cause pollution. Most of it is discarded and directly burned in the fields, which not only causes a huge waste of resources, but also produces gases such as H2S, NH3 and fly ash particles, which will also cause air pollution. Through gasification, it can be converted into usable coal gas, which can reduce pollution and utilize energy. From the perspective of clean energy, gasification will only produce a small amount of CO2 and water vapor, so gasification can be used as a clean energy and is also an indispensable energy technology for human energy reserves.

[0049] Next, the links and related substances involved in the biomass gasification process are introduced.

[0050] The biomass gasification process roughly consists of biomass pretreatment, pyrolysis and gasification processes.

[0051] Pretreatment: When biomass (such as straw) is used in the process, it needs to be pretreated because the straw is large in size, difficult to transport, and inconvenient to use.

[0052] Biomass gasification: It is composed of a series of chemical and physical reactions, which can be divided into thermal drying, thermal cracking, oxidation reaction and reduction reaction. The gasifier is the main equipment for biomass gasification reaction.

[0053] Gasifier: It is a necessary gas medium in the process of gasification. Gasifier is very important in the process of gasification. In gasification, compared with direct gasification and gasification with gasifier, the energy consumption required for gasification with gasifier will be lower and more energy-saving. Traditional coal combustion will produce a lot of pollutants, and a lot of pollutants will also be produced in the process of coal production. The use of gasifier will reduce the generation of these pollutants. Coal will produce a lot of pollutants if it is fully in contact with oxygen but not completely burned. Insufficient combustion will increase pollutants. In the process of oxygen and coal combustion, insufficient oxygen content will produce a lot of smoke, which will also produce pollutants. The sulfur element in coal reacts with oxygen to produce a lot of sulfides. Different combustion temperatures are different. High temperature will produce gas NO. Powder will also produce polluting ambient air with gas. If coal does not react completely, polluting gas will also be produced. By using gasifier, the gasifier performs chemical process on the gasified gas produced by gasification, and the polluted gas entering the atmosphere is controlled. The gasifier also produces very little polluting gas when it burns with coal. The wastewater from the reaction can also be recycled, which can also protect the environment.

[0054] Pyrolysis: Pyrolysis of biomass is the process of decomposing biomass macromolecules into small molecules through chemical reactions in the absence of oxygen, or in the absence of oxygen. Pyrolysis is a chemical reaction in a dry environment. The products of pyrolysis are solid, gaseous and liquid. Pyrolysis is a form of decomposition of a material in the absence of oxygen. Pyrolysis takes advantage of the unstable chemical properties of organic matter.

[0055] It should be understood that if the energy transfer of the model, the reaction process of the material, and the chemical reaction equation are known, a rough model (system) can be established and numerical simulation can be performed using the established model. This allows the simulation of gasification to be completed without experimental operation, which is more convenient than experiments and easier to optimize.

[0056] At present, the main simulation software used is Aspen Plus software, which simulates the gasification process of biomass through various reactors.

[0057] Figure 1 A schematic structural diagram of an existing biomass gasification system provided in an embodiment of the present application.

[0058] For example, Figure 1 As shown, the existing biomass gasification system includes a dryer a, a pyrolysis reactor b, a gasification reactor c, a mixer d and a combustion reactor e.

[0059] The pretreated biomass enters the dryer a from the entrance, and the dried biomass enters the pyrolysis reactor b for pyrolysis and decomposition into specific substances. The remaining raw materials are gasified into gasification gas through the gasification reactor c. During gasification, the gasifying agent in the mixer d enters the gasification reactor c, and then the generated coal gas component enters the combustion reactor e for combustion.

[0060] It should be understood that after the biomass is pyrolyzed and gasified, the generated gasification gas contains a large amount of heat, but in the existing gasification system, this heat is not fully utilized but is wasted.

[0061] In view of the above problems, the present invention provides a biomass gasification system.

[0062] Example 1

[0063] Figure 2 A schematic structural diagram of an improved biomass gasification system provided in an embodiment of the present application.

[0064] Exemplarily, the gasification system includes: a drying reactor 1 , a pyrolysis reactor 2 , a gasification reactor 3 , a mixer 4 and a heat exchanger assembly 5 .

[0065] Among them, the drying reactor 1 has a nitrogen inlet, a biomass inlet and an outlet. Optionally, the drying reactor 1 can be a DRY-RStoic reactor, which mainly simulates the drying process of biomass. Drying uses heat energy to gasify the moisture in the material and remove steam.

[0066] The pyrolysis reactor 2 has an inlet and an outlet, and its inlet is connected to the outlet of the drying reactor 1. Optionally, the pyrolysis reactor 2 can be a RYield reactor, which mainly simulates the pyrolysis process of biomass, that is, in an oxygen-deficient or low-oxygen environment, the biomass is heated at a temperature of 400-700°C to produce gas (mainly tar and light gas), liquid (tar) and solid (semi-coke or charcoal).

[0067] The gasification reactor 3 has an inlet and an outlet, and its inlet is connected to the outlet of the pyrolysis reactor 2. Optionally, the gasification reactor 3 can be an RBibbs reactor, which mainly simulates the gasification process of biomass, that is, the gas produced by pyrolysis and the remaining solid char react with oxygen, water vapor or carbon dioxide at a higher temperature (usually 700-1500°C) to generate more combustible gases, such as hydrogen (H2), carbon monoxide (CO) and methane (CH4).

[0068] The mixer 4 has an inlet and an outlet, and the outlet is connected to the inlet of the gasification reactor 3. Optionally, the mixer 4 can be a mixer reactor, which is mainly used to mix water vapor and air to generate gasification agent. The inlet includes a water vapor inlet and an air inlet.

[0069] The heat exchanger assembly 5 has an inlet and an outlet, wherein the inlet is connected to the outlet of the gasification reactor 3, and the outlet is respectively connected to the inlet of the drying reactor 1 and the inlet of the mixer 4. The heat exchanger assembly 5 also includes a nitrogen inlet and a water inlet.

[0070] The operation process of the present invention is introduced below: illustratively, biomass enters the drying reactor 1 through the inlet, nitrogen and water are passed into the heat exchanger assembly 5, the nitrogen heated by the heat exchanger assembly 5 enters the drying reactor 1 to dry the biomass, and then the biomass enters the pyrolysis reactor 2 for pyrolysis reaction to produce gas (mainly tar and light gas), liquid (tar) and solid (semi-coke or charcoal), the gas and solid enter the gasification reactor 3 for gasification reaction, the heat exchanger assembly 5 heats water to generate water vapor, and the mixer 4 mixes the water vapor and air to obtain a gasifying agent, and the gasifying agent enters the gasification reactor 3 to participate in the gasification reaction.

[0071] In the above embodiment, by adding a heat exchanger assembly, the gasified gas is passed into the heat exchanger assembly to heat the nitrogen, thereby improving the drying efficiency; it can provide energy for water, heat the water to become water vapor as the main component of the gasification agent; and the energy utilization rate of the gasification system is improved from the above two aspects.

[0072] Optionally, the heat exchanger assembly 5 includes a first heat exchanger 5-1-1 and a second heat exchanger 5-2. The first heat exchanger 5-1-1 and the second heat exchanger 5-2 can be connected in the following two ways.

[0073] Figure 3 A schematic diagram of the structure of the connection between a first heat exchanger and a second heat exchanger provided in an embodiment of the present application.

[0074] For example, Figure 3 As shown, the first heat exchanger 5-1-1 has a first inlet A1, a second inlet A2, a first outlet B1 and a second outlet B2. The first inlet A1 is a nitrogen inlet, the second inlet A2 is connected to the outlet of the gasification reactor 3, and the first outlet B1 is a nitrogen outlet, which is connected to the nitrogen inlet of the drying reactor 1. It should be understood that the first heat exchanger 5-1-1 can use the heat in the gas generated by gasification to heat the nitrogen.

[0075] The second heat exchanger 5-2 has a first inlet C1, a second inlet C2, a first outlet D1 and a second outlet D2. The first inlet C1 is a water inlet, the second inlet C2 is connected to the second outlet B2 of the first heat exchanger 5-1; the first outlet D1 is connected to the inlet of the mixer 4. It should be understood that the second heat exchanger 5-2 can use the heat in the gas generated by gasification to heat water into water vapor.

[0076] like Figure 3As shown, the gasification system further comprises a combustion reactor 6 having a coal gas inlet, which is connected to the second outlet D2 of the second heat exchanger 5-2. Optionally, the combustion reactor 6 can be a Burn reactor, which is mainly used to simulate the combustion process of coal gas.

[0077] Exemplarily, biomass enters the drying reactor 1 through the inlet, and nitrogen heated by the first heat exchanger 5-1-1 enters the drying reactor 1 to dry the biomass. Then the biomass enters the pyrolysis reactor 2 for pyrolysis reaction to produce gas (mainly tar and light gas), liquid (tar) and solid (semi-coke or charcoal). The gas and solid enter the gasification reactor 3 for gasification reaction. The second heat exchanger 5-2 heats water to generate water vapor, and the mixer 4 mixes the water vapor and air to obtain a gasifying agent. The gasifying agent enters the gasification reactor 3, participates in the gasification reaction, and generates combustible gas (such as hydrogen, carbon monoxide and methane). The combustible gas enters the combustion reactor 6 for combustion treatment.

[0078] Figure 4 A schematic diagram of another structure of the connection between a first heat exchanger and a second heat exchanger provided in an embodiment of the present application.

[0079] For example, Figure 4 As shown, the second inlet A2 of the first heat exchanger 5-1-1 is connected to the outlet of the gasification reactor 3, and the second outlet B2 of the first heat exchanger 5-1-1 is connected to the inlet of the combustion reactor 6; the second inlet C2 of the second heat exchanger 5-2 is connected to the outlet of the gasification reactor 3, and the second outlet D2 of the second heat exchanger 5-2 is connected to the inlet of the combustion reactor 6.

[0080] In the above embodiment, by adding a first heat exchanger and passing the vaporized gas into the first heat exchanger, the nitrogen can be heated, thereby improving the drying efficiency; by adding a second heat exchanger, energy can be provided for water, and the water can be heated to become water vapor as the main component of the gasification agent; the energy utilization rate of the gasification system is improved from the above two aspects.

[0081] Example 2

[0082] Figure 5 A schematic structural diagram of another improved biomass gasification system provided in an embodiment of the present application.

[0083] Exemplarily, the gasification system includes: a drying reactor 1, a pyrolysis reactor 2, a gasification reactor 3, a mixer 4, a first heat exchanger 5-1, a second heat exchanger 5-2, a combustion reactor 6, a condenser 7, a first separator 8, a second separator 9, a third separator 10 and a fourth separator 11.

[0084] The condenser 7 has a gas inlet and a gas outlet. The gas inlet is connected to the second outlet D2 of the second heat exchanger 5-2 for cooling water vapor carried in the gas.

[0085] The first separator 8 has an outlet and an inlet, wherein the inlet is connected to the gas outlet of the condenser 7, and the outlet is connected to the inlet of the combustion reactor 6. The first separator 8 is mainly used to separate the cooled water vapor.

[0086] It should be understood that the gasified gas includes a mixture of the main component of coal gas and water vapor. To separate the main component of the coal gas, the water vapor needs to be cooled into liquid water, and then the water in the coal gas is separated by a separator to obtain the main component of the coal gas.

[0087] The inlet of the second separator 9 is connected to the outlet of the gasification reactor 3, and the outlet of the second separator 9 is connected to the second inlet A of the first heat exchanger 5-1, which is mainly used to separate the ash in the gasification gas.

[0088] The inlet of the third separator 10 is connected to the outlet of the drying reactor 1 , and the outlet of the third separator 10 is connected to the inlet of the pyrolysis reactor 2 . The third separator 10 is used to separate nitrogen and moisture carried in the biomass to be gasified.

[0089] The inlet of the fourth separator 11 is connected to the outlet of the pyrolysis reactor 2 , and the outlet of the fourth separator 11 is connected to the inlet of the gasification reactor 3 , for separating tar from the pyrolysis product.

[0090] Optionally, the first separator 8, the second separator 9, the third separator 10 and the fourth separator 11 may be Sep separators.

[0091] Exemplarily, the pretreated biomass enters the drying reactor 1, and then the nitrogen and water are separated by the third separator 10. The remaining raw materials are pyrolyzed by the pyrolysis reactor 2 to generate gas, liquid and solid. The liquid is separated by the fourth separator 11. The gas and solid enter the gasification reactor 3 for gasification reaction to generate gasified gas. The main components of the gasified gas are CO, H2, CH4 and CO2. After passing through the first heat exchanger 5-1 and the second heat exchanger 5-2, the gasified gas enters the condenser 7, and the water vapor is cooled by the condenser 7 to obtain liquid water, and then the liquid water is separated by the first separator 8 to obtain dry gasified gas.

[0092] It should be understood that the above-mentioned biomass pyrolysis process and gasification process can be achieved by a gasifier, which is the main equipment for biomass gasification reaction. Since there are multiple key chemical reactions in the gasification process, the design and selection of the reactor is a key factor in whether the efficient conversion of biomass energy can be achieved.

[0093] Gasifiers can be divided into fixed bed gasifiers, fluidized bed gasifiers and gasified bed gasifiers. Fixed bed gasifiers are more convenient, so they can be used. Fixed bed gasifiers are further divided into updraft, downdraft, transverse suction and open-heart types. Updraft reaction structures are simple, so updraft gasifiers can be used. In an updraft fixed bed gasifier, fuel and gasifier flow in different directions. First, the gasifier is heated from the ash layer of the gasifier to fully react with the straw raw material. The carbon in the straw and the oxygen in the gasifier undergo oxidation reactions, and the reaction products are A large amount of carbon dioxide and a small amount of carbon monoxide are produced, and heat is released at the same time. The products of the oxidation reaction and the remaining gasifier go to the reduction layer with the air. The gaseous carbon dioxide produced by oxidation and the water vapor of the gasifier react with the carbon to produce carbon monoxide and hydrogen. Hydrogen and carbon monoxide are the main components of coal gas. The products of the reduction reaction and the heat rise to the thermal decomposition layer to heat the fuel, which is thermal decomposition. The products of the thermal decomposition layer, reduction layer and oxidation layer are coal gas. These gases are then dried and discharged from the coal gas outlet to produce product coal gas.

[0094] Next, we introduce the numerical simulation of the biomass gasification process using Aspen Plus to evaluate the waste heat reuse in the gasification process before and after the improvement of the gasification system.

[0095] Step 1: AspenPlus modeling process.

[0096] Specifically, the simulation devices (simulation systems) required for the model flow chart include models of reactors, mixers, separators and heat exchangers. Each model has different functions and the model environment also has different conditions. The main reactor modules used when building a model with AspenPlus include: RYield, RGIbbs and RStoic.

[0097] The reactor model in the process flow is used for different reaction conditions, such as temperature, pressure, flow rate, etc., when a chemical reaction occurs; the mixer is used to mix substances in the process flow or merge different streams; the separator is used to separate different substances in the reaction process, such as the separation of gaseous substances and solid substances, and the separation of substances in different phases; the heat exchanger model is used for heat transfer between two or more different fluids. The embodiment of the present application uses three reactor models, a separator model, a mixer model, and two heat exchanger models.

[0098] The reactors used are RStoic, RYield and RGIBBs. RStoic is suitable for drying straw. RYield is a yield reactor, and the functional decomposition is straw powder, which can be used to simulate the distribution of yield. RGibbs is used to burn straw, and the chemical reaction is calculated using the chemical composition of the raw materials by minimizing Gibbs free energy.

[0099] The mixer uses a Mixer logistics mixer, which mixes multiple logistics into one logistics. It is suitable for mixing tees, logistics mixing operations, adding hot streams and adding work streams.

[0100] The separator used is the Sep component separator, which is simulated using a specified flow rate or separation ratio separation combination.

[0101] The parameters that RStoic needs to input are pressure P, temperature T, equilibrium constant K, and reaction equation, which are used to calculate the nuclear reaction calorific value of specific reaction products.

[0102] The parameters that RYield needs to input are pressure P, temperature T and yield parameters, which are used to calculate the reaction ratio of known reaction products and chemical reactors with unknown reaction kinetic models, as well as to calculate the flow rates of various reaction products based on the chemical reaction equivalents set by the user.

[0103] The parameters that RGibbs needs to input are pressure P and temperature T, which are used to calculate single-phase chemical equilibrium, or to perform phase equilibrium and chemical equilibrium calculations on multiple components in parallel. The reaction calculation is performed using the minimum free energy of the system when the reaction is in equilibrium. For the case of multiple fluid phases, the equilibrium can be determined without a chemical reaction equation.

[0104] The parameters that Mixer needs to input are pressure P, temperature T, and flash convergence parameters, which are used to mix multiple logistics or work flows into one logistics.

[0105] The parameters that Sep needs to input are pressure P, split flow components, and substances acting on different phases.

[0106] During the experimental simulation, due to the existence of conditional errors, some conditions are assumed: for example, the gasifier operates stably, the pressure remains stable, all elements in the fuel are converted into gas, the ash does not react, the gasifier and fuel react completely, and the chemical reactions of the gasifier are chemically balanced. During the gasification process, the most important conditions are the temperature, pressure, air and steam consumption of the gasifier, the consumption rate of raw materials, the logistics rate, and the production rate. The structure of the gasifier remains consistent.

[0107] Figure 6 A schematic diagram of a pyrolysis reaction process provided in an embodiment of the present application.

[0108] For example, taking biomass as straw as an example, combined with Figure 4The specific steps are briefly introduced as follows: STRAW-IN is the drying of straw in RStoic, S1 is the heat in the coal gas transferred to RStoic through a heat exchanger to dry the straw, which is the utilization of waste heat from biomass. After the straw is dried, the solid straw and gas are separated by a separator Sep, and the gas is mainly water vapor and N2. The remaining straw is pyrolyzed by RYield, and then the pyrolysis gas and the remaining solid are separated by a separator Sep. The remaining solid is gasified by RBibbs. This step also requires gasification agents air and water vapor. S2 is water pyrolyzed into water vapor through a heat exchanger, and Mixer mixes water vapor and air as a gasification agent. After gasification, Sep is used to separate ash and coal gas, and the coal gas uses a heat exchanger to transfer heat to N2 for heating. After the coal gas passes through the first heat exchanger 5-1 and the second heat exchanger 5-2, it passes through a condenser 7, and the water in the coal gas is separated by the condenser 7, and then the required gasification product (GAS) can be obtained.

[0109] Step 2: Set parameters for the established model.

[0110] First, set the global characteristics. Specifically, straw and ash are mixtures with many components, but some of the C, S, CO, CO2, H2, N2, O2, etc. can be directly selected in AspenPlus. STRAW and ASH are straw and ash, which need to be defined manually, so the type of logistics is MIXCINC and the unit of measurement is US-1.

[0111] Secondly, input the components. Specifically, straw and ash are mixtures. Straw is the remaining part of crops after harvesting fruits. Different crops have different components. In the experimental simulation process, each component and element cannot be directly calculated in Aspen Plus software. It can only be a rough chemical reaction process. There are many complex chemical reactions in the entire gasification process. In the rough chemical reaction process, the components required are STRAW, O2, N2, H2O, H2, CO, CO2, CH4, NO and ASH, among which STRAW and ASH are mixtures.

[0112] Then, select the physical property method and physical property group. Specifically, the physical property method mainly consists of two factors: the scope of application of the physical property method and the properties of the substance to be determined, such as polarity and physical properties. The physical property group is mainly a collection of thermodynamic properties, transport properties and other physical properties, which can be used in physical property tables and physical property analysis.

[0113] The PR-BM equation is used for component selection. Since straw is a mixture, enthalpy and density can be calculated. Since straw is a mixture, Aspen Plus does not have parameters corresponding to straw, HCOALGEN is used to calculate the enthalpy value of straw and DCOALIGT is used to calculate the density of straw. Both STRAW and ASH use HCOAIGEN to calculate enthalpy for the enthalpy model and DCOALIGT for the density model.

[0114] To calculate density, RBibbs cannot be used to calculate straw directly, so we must first use RYield to decompose the straw into pure substances such as C, H2, O2, N2, S, H2O and Ash, and then use RBibbs to react. The calorific value of STRAW is 12552.54MJ / kg.

[0115] The physical property group is mainly about the collection of thermodynamic properties, transport properties and other physical properties.

[0116] MASSFLMX represents mass flow rate; HMX represents enthalpy; RHOMX represents density; CPMX represents specific heat at constant pressure; PCMX represents pressure; MUMX represents viscosity; KMX represents conductivity; SIGMAMX represents surface tension; MWMX represents molecular weight; these are the main physical properties.

[0117] Furthermore, logistics is specified. Specifically, the calorific value of straw is 12552.54 MJ / kg, and data analysis is performed on straw and gasifier: industrial analysis, sulfur analysis and elemental analysis can be performed on straw.

[0118] Different stream analyses can be viewed using component properties in AspenPlus software.

[0119] Table 1 is an example of the analysis results of industrial analysis and elemental analysis of straw.

[0120] Table 1

[0121]

[0122] Exemplarily, as shown in Table 1, element analysis: ash: 15.29%, carbon 40.67%, hydrogen 5.73%, nitrogen 0.8%, sulfur 0.01%, oxygen 32.3%, sulfur analysis: sulfate 0.01%.

[0123] The environment, pressure, temperature, flow rate, etc. are set for the logistics of each module. For example, the temperature of the straw is 25 degrees Celsius, the pressure is 0.101325MPa, and the flow rate is 2500kg / hr.

[0124] Unit module environment settings:

[0125] The pressure of RStoic is 1atm and the temperature is 600 degrees Celsius.

[0126] The pressure of RYiled is 1atm.

[0127] The pressure at RGibbs is 1 atm and the temperature is 838 degrees Celsius.

[0128] For the before and after experiments, the environment, temperature, pressure and flow rate are the same, only the calculation results are different.

[0129] Finally, the simulation results are analyzed.

[0130] Since the main components of coal gas are CO, H2, and CH4, the gas production can be compared by comparing the coal gas production of the two simulation systems. In the improved system, since the waste heat of the pyrolysis gas is used to heat N2 and H2O through the heat transferer, the temperature change of N2 and H2O in the improved model system during the process of passing through the heat transferer can be calculated, and the energy value transferred by the heat transferer to N2 and H2O can be calculated using the formula Q=CMΔT, so as to compare the energy before and after.

[0131] Specifically, we first set up a sensitivity analysis, and then perform a sensitivity analysis in the model analysis tool. We set CO, H2, and CH4 as acquisition variables, and the reactor temperature as the manipulated variable, and obtain the changes in CO, H2, and CH4 with temperature. In terms of energy calculation, we set the temperature changes of N2 and H2O gases as acquisition variables, and the reactor temperature as the manipulated variable, and obtain the changes in the temperature of N2 and H2O gases with the temperature of the reactor.

[0132] Secondly, combined Figures 7 to 9 Analyze the change of gas with temperature. Figure 7 A schematic diagram of the change of CO content with temperature provided in an embodiment of the present application, Figure 8 A schematic diagram of the change of H2 content with temperature provided in an embodiment of the present application, Fig. 9 A schematic diagram of the variation of CH4 content with temperature provided in an embodiment of the present application.

[0133] like Figure 7 As shown, the horizontal axis is temperature, which is set to 400°C, 450°C, 500°C, 550°C, 600°C, and 650°C respectively; the vertical axis is the mass of CO, the blue line represents the CO content of the original device (unadvanced gasification system), and the orange line represents the CO content of the improved device (improved gasification system). It can be seen that in the two gasification systems, the CO content increases with increasing temperature.

[0134] like Figure 8 As shown, in both gasification systems, the H2 content decreases with increasing temperature.

[0135] like Fig. 9 As shown, in both gasification systems, the H2 content decreases with increasing temperature.

[0136] Since the content of CO is much greater than that of gas H2 and CH4, the temperature setting is 650℃, at which the CO yield is the highest. At the same time, it can be seen that the gas output of the original device is higher than that of the improved device, but the higher part is small and can be ignored.

[0137] Fig.10 The figure is a schematic diagram of the before and after comparison of the gas contents of the original device and the improved device at 650°C. It can be seen that at 650°C, the CO content of the original device is slightly higher than that of the improved device, and the H2 content of the original device is basically the same as that of the improved device.

[0138] The gas yields for the original and improved plants were then calculated.

[0139] Gas yield Φ = gas output / straw raw material mass. Gas output is the sum of the masses of CO, H2, and CH4.

[0140] pass Figures 7 to 9 The efficiency of gasification can be determined by calculating the ratio of the output to the feed. The feed is the flow rate of straw, 2500kg / hr. The main components of coal gas are CO, H2 and CH4, so the output is the flow rate of CO, H2 and CH4. The ratio of the output to the feed at 650℃ is calculated. The higher the ratio, the higher the gasification efficiency.

[0141] At 650°C, the flow rates of CO, H2, and CH4 in the original device are M1 = 2143.33 kg / hr, M2 = 171.138 kg / hr, and M3 = 0.0391497 kg / hr, respectively.

[0142] M 原始装置＝ 2143.33+171.138+0.0391497=2314.5071497kg / hr.

[0143] Gas yield Φ 原始装置 =2314.5071497÷2500=92.5%.

[0144] At 650°C, the flow rates of CO, H2, and CH4 in the improved device are M4 = 2119.3 kg / hr, M5 = 169.633 kg / hr, and M6 = 0.0258803 kg / hr, respectively.

[0145] M 改进装置 =2119.3+169.633+0.0258803=2289.191803kg / hr,

[0146] Gas yield Φ 改进装置 =2289.191803÷2500=91.5%.

[0147] It can be seen that the gas conversion rate of the original device is slightly higher than that of the improved device, but the higher part is very small and they are basically the same.

[0148] Fig.11 A schematic diagram of nitrogen and water changing with temperature provided in an embodiment of the present application.

[0149] The improved device mainly provides heat through two heat transfer devices, which are also the main devices for biomass pyrolysis waste heat, and are used to heat N2 and H2O respectively to achieve the effect of biomass pyrolysis waste heat reuse. The temperature rise of N2 and H2O can be calculated respectively, and the energy can be calculated using Q=CMΔT, and the before and after can be compared through the energy aspect. Fig.11 As shown, the horizontal axis is set to temperature, and the vertical axis is set to the temperature change of N2 and H2O, and the temperatures are 400℃, 450℃, 500℃, 550℃, 600℃ and 650℃. It can be seen that the higher the temperature, the higher the temperature of N2 and H2O, so the temperature of 650℃ is selected.

[0150] At 650℃, the temperature of N2 is T N2 =285℃, the temperature of H2O is T H2O =272℃. The initial temperatures are 25℃ and 134℃ respectively. So ΔT N2 =260℃, ΔT H2O =138℃, by calculating Q N2 =6760KJ, Q H2O = 14352KJ. All this energy is used through the heat transfer device, so in terms of energy utilization, the improved device is more efficient than the original device.

[0151] In summary, Φ 原始装置 =92.5%,Φ 改进装置 =91.5%. The gas yield of the original device is higher than that of the improved device. However, since the gas yield of the original device is more than that of the improved device, it can be basically considered to be equal. However, in terms of energy utilization, the improved device can use the waste heat of biomass pyrolysis to heat N2 and H2O, Q N2 =6760KJ, Q H2O =14352KJ, so under the condition of unchanged gas yield, the gasification simulation device of the present invention can improve energy utilization.

[0152] It should be pointed out that the specific implementation methods described above can enable those skilled in the art to understand the invention more comprehensively, but do not limit the invention in any way. Therefore, although the invention has been described in detail in this specification and embodiments, those skilled in the art should understand that the invention can still be modified or replaced by equivalents; and all technical solutions and improvements that do not deviate from the spirit and scope of the invention are included in the protection scope of the patent for the invention. Any figure mark in the claims should not be regarded as limiting the claims involved. Any simple change or equivalent replacement of the technical solution that can be obviously obtained by any technician familiar with the field within the technical scope disclosed in the present invention belongs to the protection scope of the present invention.

Claims

1. A biomass gasification system, characterized in that: It comprises a drying reactor (1), a pyrolysis reactor (2) and a gasification reactor (3) which are connected in sequence, and A mixer (4), the outlet of which is connected to the inlet of the gasification reactor (3); a heat exchanger assembly (5), the inlet of which is connected to the outlet of the gasification reactor (3), and the outlet of which is respectively connected to the inlet of the drying reactor (1) and the inlet of the mixer (4); The biomass to be gasified is sequentially dried in a drying reactor (1), pyrolyzed in a pyrolysis reactor (2), and gasified in a gasification reactor (3), and is converted from a solid into a gasified gas. The gasified gas enters the heat exchanger assembly (5) to heat the nitrogen and water in the heat exchanger assembly (5). The heated nitrogen enters the drying reactor (1) to dry the biomass to be gasified. The heated water becomes water vapor. The water vapor enters the mixer (4) to mix with air to form a gasifying agent. The gasifying agent enters the gasification reactor (3) to participate in the gasification reaction.

2. The biomass gasification system according to claim 1, characterized in that: The heat exchanger assembly (5) comprises a first heat exchanger (5-1) and a second heat exchanger (5-2): The inlet of the first heat exchanger (5-1) is in communication with the outlet of the gasification reactor (3), and the outlet of the first heat exchanger (5-1) is in communication with the drying reactor (1); The inlet of the second heat exchanger (5-2) is connected to the outlet of the first heat exchanger (5-1); The gasified gas enters the first heat exchanger (5-1) from the outlet of the gasification reactor (3) to heat nitrogen, and enters the second heat exchanger (5-2) to heat water to obtain water vapor.

3. The biomass gasification system according to claim 1, characterized in that: The heat exchanger assembly (5) comprises a first heat exchanger (5-1) and a second heat exchanger (5-2): The inlet of the first heat exchanger (5-1) is in communication with the outlet of the gasification reactor (3), and the outlet of the first heat exchanger (5-1) is in communication with the drying reactor (1); The inlet of the second heat exchanger (5-2) is connected to the outlet of the first heat exchanger (5-1); The gasified gas enters the first heat exchanger (5-1) from the outlet of the gasification reactor (3) to heat nitrogen, and enters the second heat exchanger (5-2) to heat water to obtain water vapor.

4. The biomass gasification system according to claim 2, characterized in that: Also includes: A combustion reactor (6), the inlet of which is connected to the outlet of the second heat exchanger (5-2), is used for burning the gasification gas.

5. The biomass gasification system according to claim 4, characterized in that: Also includes: a condenser (7), the inlet of which is connected to the outlet of the second heat exchanger (5-2), and the condenser (7) is used to cool the water vapor carried in the gasified gas; A first separator (8), whose inlet is connected to the outlet of the condenser (7), and whose outlet is connected to the inlet of the combustion reactor (6), is used to separate the cooled water vapor.

6. The biomass gasification system according to claim 2, characterized in that: Also includes: The second separator (9) has an inlet connected to the outlet of the gasification reactor (3), and an outlet connected to the inlet of the first heat exchanger (5-1). The second separator (9) is used to separate ash from the gasification gas.

7. The system according to claim 1 or 2, characterized in that: Also includes: The third separator (10) has an inlet connected to the outlet of the drying reactor (1) and an outlet connected to the inlet of the pyrolysis reactor (2). The third separator (10) is used to separate nitrogen and moisture carried in the biomass to be gasified.

8. The system according to claim 1 or 2, characterized in that: Also includes: The fourth separator (11) has an inlet connected to the outlet of the pyrolysis reactor (2), and an outlet connected to the inlet of the gasification reactor (3). The fourth separator (11) is used to separate the tar produced after the pyrolysis of the biomass to be gasified.

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