A system and method for co-production of char and steam from periodic pyrolysis of shaped biomass

Abstract

The application discloses a system for co-production of carbon and steam by periodic pyrolysis of shaped biomass, wherein a biomass pretreatment unit is connected with a group periodic pyrolysis unit of shaped biomass, a biomass pyrolysis volatile energy recovery unit, the group periodic pyrolysis unit of shaped biomass is connected with a biomass pyrolysis volatile delivery system, the biomass pyrolysis volatile delivery system is connected with the biomass pyrolysis volatile energy recovery unit and a waste heat boiler, the biomass pyrolysis volatile energy recovery unit and the waste heat boiler are connected with a tail gas purification unit, a biomass shaped fuel delivery unit is connected with the biomass pretreatment unit and the group periodic pyrolysis unit of shaped biomass, and the waste heat boiler is further connected with a steam user unit. The application also provides a method for co-production of carbon and steam by periodic pyrolysis of shaped biomass. The application realizes efficient, large-scale, economic and environmentally-friendly co-production of biomass carbon and steam.

Description

Technical Field

[0001] This invention belongs to the field of high-value utilization technology and equipment for biomass resource and energy, and particularly relates to a system and method for the periodic pyrolysis of biomass to produce char and steam. Background Technology

[0002] Biomass is an important renewable energy source, and its efficient and clean utilization is crucial for achieving the "dual carbon" goal (carbon reduction, carbon emission reduction, and carbon sequestration). Pyrolysis is one of the main technological pathways for biomass conversion and utilization, converting biomass into various products such as biochar, bio-oil, and pyrolysis gas. However, the current application of biomass pyrolysis technology faces several challenges. First, in terms of technical routes, biomass pyrolysis processes are divided into two distinct routes: one primarily for producing fuel oil and fuel gas, and the other primarily for producing biochar. The process for producing fuel oil and fuel gas involves controlling the pyrolysis reaction at relatively high temperatures. Its drawbacks include the complex composition of the resulting fuel oil, making it difficult to convert and utilize at high value, and the potential environmental hazards posed by the waste liquid generated during the fuel oil conversion and upgrading process, thus limiting its industrial-scale application. In contrast, the process for producing biochar through biomass pyrolysis, by controlling the temperature of the pyrolysis reaction and achieving staged pyrolysis, improves the yield of high-value biochar, enabling the full industrial and practical application of biochar. Secondly, in terms of techno-economic efficiency, the pyrolysis volatiles produced by biochar preparation processes have a certain calorific value and energy. However, the energy from the pyrolysis volatiles in traditional biochar preparation methods is not fully recovered and utilized, resulting in energy waste and poor energy consumption and techno-economic efficiency. Furthermore, in terms of equipment and scale-up, traditional biochar preparation units typically operate in a single-unit, intermittent manner. The small scale of biomass processing in a single pyrolysis unit leads to low production efficiency, limited processing capacity, and difficulties in expanding production. Summary of the Invention

[0003] To overcome the shortcomings of existing technologies, this invention provides a system and method for the co-production of biomass charcoal and steam through periodic pyrolysis. This system achieves efficient, large-scale, economical, and environmentally friendly co-production of biomass charcoal and steam through grouped periodic pyrolysis, volatile matter diversion, and energy cascade utilization.

[0004] The technical solution adopted by this invention to solve its technical problem is: A system for the periodic pyrolysis of briquetted biomass to co-produce char and steam includes a biomass pretreatment unit, a biomass briquetted fuel conveying unit, a grouped briquetted biomass periodic pyrolysis unit, a biomass pyrolysis volatile matter conveying system, a biomass pyrolysis volatile matter energy recovery unit, a waste heat boiler, a tail gas purification unit, and a steam user unit. The biomass pretreatment unit is connected to the grouped briquetted biomass periodic pyrolysis unit and the biomass pyrolysis volatile matter energy recovery unit. The grouped briquetted biomass periodic pyrolysis unit is connected to the biomass pyrolysis volatile matter conveying system. The biomass pyrolysis volatile matter conveying system is connected to the biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler. The biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler are connected to the tail gas purification unit. The biomass briquetted fuel conveying unit is connected to the biomass pretreatment unit and the grouped briquetted biomass periodic pyrolysis unit. The waste heat boiler is also connected to the steam user unit.

[0005] The material pretreatment unit is used to crush, screen, dry and shape biomass raw materials, including a biomass crushing device, a screening device, a conveying device, a wet material silo, a drying device, a biomass powder separator, a dry material silo, a biomass fuel shaping and shaped fuel assembly device connected in sequence.

[0006] The group-type molten biomass periodic pyrolysis unit utilizes multiple sets of collaboratively operating biomass pyrolysis reactors to thermally decompose molten biomass into biomass char. It sequentially generates low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas containing energy-rich volatiles according to a certain cycle. The unit includes multiple molten biomass periodic pyrolysis reactors, where the molten biomass undergoes an oxygen-deficient pyrolysis chemical reaction under controlled air flow and pyrolysis temperature conditions. Each biomass pyrolysis reactor periodically generates low-temperature pyrolysis combustible volatiles, primarily composed of H2, CO, CH4, water vapor, and tar organic matter, and high-temperature pyrolysis flue gas volatiles, primarily composed of CO2 and N2, ultimately forming char with carbon as the main component.

[0007] The biomass pyrolysis volatile matter conveying system is used to convey low-temperature pyrolysis fuel gas generated from the pyrolysis of shaped biomass, tar generated from the cooling of low-temperature pyrolysis fuel gas, and high-temperature pyrolysis flue gas. It includes low-temperature pyrolysis fuel gas conveying pipelines and valves, high-temperature pyrolysis flue gas conveying pipelines and valves, pyrolysis fuel gas tar pools, as well as tar pipelines, tar pumps, circulating water pipelines, and circulating water pumps.

[0008] The biomass pyrolysis volatile matter energy recovery unit is used to receive a portion of the biomass pyrolysis volatile matter and use the recovered volatile matter energy to perform drying pretreatment on the biomass powder, including a high-temperature combustion chamber and an air passage.

[0009] The waste heat boiler unit is used to receive a portion of the biomass pyrolysis volatiles and convert the recovered volatile energy into high-temperature steam, including a boiler furnace and an air inlet.

[0010] The exhaust gas purification unit is used to remove pollutants such as sulfur and dust from the exhaust gas of the waste heat boiler and biomass pretreatment unit, and includes a desulfurization device, a dust removal device, an induced draft fan and a chimney.

[0011] The biomass briquette fuel conveying unit is used to place briquette biomass in the pyrolysis unit and to remove and place biomass char from the pyrolysis unit when pyrolysis is completed. It includes biomass profile containers, biomass char containers, and container hoisting equipment.

[0012] The steam user unit includes a heat exchanger for exchanging heat between steam and a cryogenic medium.

[0013] The steam user unit is used to utilize the steam generated by the waste heat boiler for production or domestic purposes.

[0014] Furthermore, in the biomass powder drying device of the biomass pretreatment unit, the wet biomass powder with high moisture content comes into contact with the high-temperature flue gas from the biomass pyrolysis volatile matter energy recovery unit. After the moisture in the wet biomass powder evaporates and enters the flue gas, dry biomass is produced. The water vapor content of the high-temperature flue gas increases and the temperature decreases.

[0015] In the grouped biomass periodic pyrolysis unit, the reaction cycles of each biomass periodic pyrolysis device alternate, and the reaction stage of the biomass in each pyrolysis device can be flexibly adjusted. All pyrolysis devices in the grouped biomass periodic pyrolysis unit can operate simultaneously, or only some devices can operate.

[0016] In the biomass pyrolysis volatile matter conveying system, the low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas of each biomass periodic pyrolysis unit enter separate conveying channels and are connected through these channels. During operation, each biomass periodic pyrolysis unit is connected to the low-temperature pyrolysis fuel gas channel and the high-temperature pyrolysis flue gas channel. Both the low-temperature pyrolysis fuel gas channel and the high-temperature pyrolysis flue gas channel are equipped with valves to control the gas delivery to the energy recovery unit and the waste heat boiler unit. The low-temperature pyrolysis fuel gas channel uses gravitational potential difference and circulating water to transport the tar and condensate generated from the cooling of the pyrolysis fuel gas in the channel to the pyrolysis fuel gas tar pool.

[0017] The biomass pyrolysis volatile matter energy recovery unit utilizes one or more of the following: low-temperature biomass pyrolysis fuel gas, biomass pyrolysis fuel gas tar, high-temperature flue gas generated from the combustion of other supplementary fuels in the high-temperature combustion chamber, or high-temperature biomass pyrolysis flue gas, to dry the wet biomass in the biomass powder drying device of the biomass pretreatment unit.

[0018] The waste heat boiler unit uses one or more of the following: biomass low-temperature pyrolysis fuel gas, high-temperature flue gas generated from the combustion of other supplementary fuels, or biomass high-temperature pyrolysis flue gas, to heat water and generate high-temperature, high-pressure steam.

[0019] The exhaust gas purification unit performs desulfurization and dust removal purification treatments on the flue gas from the waste heat boiler unit and the exhaust gas from the biomass pretreatment unit, respectively.

[0020] The biomass briquette fuel conveying unit can accurately place biomass briquette containers into each biomass periodic pyrolysis unit or remove biomass char containers from the biomass periodic pyrolysis unit and place them at the storage location.

[0021] A method for producing charcoal and steam through periodic pyrolysis of biomass, comprising the following steps: 1) In the biomass pretreatment unit, after the biomass raw materials are crushed, screened, transported and stored, they enter the drying device. The high-temperature flue gas provided by the biomass pyrolysis volatile matter energy recovery unit is used to dry the wet biomass powder to produce dry biomass powder, which is then processed into biomass briquettes fuel by the molding device. 2) Biomass briquettes are fed into the grouped briquetted biomass periodic pyrolysis unit through the biomass briquette fuel conveying unit. In the pyrolysis reactor, an oxygen-deficient thermal decomposition chemical reaction occurs, periodically generating low-temperature pyrolysis combustible volatiles mainly composed of H2, CO, CH4, a small amount of water vapor and tar organic matter, and non-combustible high-temperature pyrolysis flue gas volatiles mainly composed of CO2 and N2, and finally forming biomass char mainly composed of carbon elements. 3) Low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas are transported to the biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler unit respectively through the biomass pyrolysis volatile matter conveying system. Among them, a portion of the low-temperature pyrolysis fuel gas and the tar produced by its cooling, as well as the high-temperature pyrolysis flue gas, enter the biomass pyrolysis volatile matter energy recovery unit. In the high-temperature combustion chamber, a large amount of high-temperature flue gas is generated through combustion. The flue gas is then passed into the biomass powder drying device of the biomass pretreatment unit to dry the wet biomass powder. Another portion of the low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas enter the waste heat boiler unit, where they are combusted and water is heated to generate high-temperature and high-pressure steam. The conveyance of low-temperature pyrolysis fuel gas, high-temperature pyrolysis flue gas, and pyrolysis fuel gas tar to the biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler unit is flexibly controlled through the low-temperature pyrolysis gas channel and valves, the high-temperature pyrolysis flue gas channel and valves, and the tar pipeline and tar pump. 4) The high-temperature and high-pressure steam generated by the waste heat boiler unit is transported to the steam user unit, where heat is exchanged through a heat exchanger and supplied to the user in the form of hot water or steam. After releasing heat, the high-temperature and high-pressure steam becomes condensate and is transported back to the waste heat boiler through a condensate pump. 5) The exhaust gas generated by the biomass pretreatment unit and the waste heat boiler unit enters the exhaust gas purification unit, and after desulfurization and dust removal purification treatment, it is discharged through the chimney.

[0022] The beneficial effects of this invention are mainly reflected in: 1. By controlling the periodic pyrolysis process, stable production of high-quality biochar has been achieved. The method of this invention precisely controls the reaction temperature and air flow rate of each pyrolysis unit, causing it to sequentially undergo a low-temperature pyrolysis stage (300-500℃, air equivalence ratio 0.05-0.15) and a high-temperature pyrolysis stage (800-900℃, air equivalence ratio 0.20-0.25). These process conditions effectively avoid over-combustion, ensuring that the final product, biochar, has high fixed carbon content, high calorific value, and high mechanical strength, significantly enhancing the product's economic value and market competitiveness. 2. By fully recovering and recycling the energy from the volatile matter in biomass pyrolysis, the economic efficiency of the technology is significantly improved. This invention's system, through the control of pipelines and valves, recovers and comprehensively utilizes the energy contained in the low-temperature pyrolysis fuel gas, high-temperature pyrolysis flue gas, and by-product tar generated during the pyrolysis process. This significantly improves the overall energy efficiency of the system, achieving a self-sufficient energy supply cycle within the system. It eliminates the need to rely on expensive external fuels, resulting in low operating costs and high economic benefits. 3. Large-scale, continuous, and flexible production is achieved through grouped pyrolysis units and modular collaborative operation. This invention employs multiple periodic pyrolysis units operating in parallel, and uses system scheduling to alternate the reaction cycles of the pyrolysis units, overcoming the bottlenecks of discontinuous production, small scale, and poor flexibility of traditional single-unit equipment. The system described in this invention can adjust the biomass processing capacity by changing the number of operating units, easily achieving large-scale production; the periodic alternation of the pyrolysis units ensures the continuity of product output; and the system can flexibly adjust the operating load according to raw material or market demand, providing operational flexibility. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the overall system for the periodic pyrolysis of biomass to produce char and steam.

[0024] The attached figures are labeled as follows: A(a), biomass pretreatment unit, including: A1(a1), biomass crushing and screening device; A2(a2), biomass conveying device and wet silo; A3(a3), biomass powder drying device; A4(a4), first-stage biomass powder cyclone separator; A5(a5), drying tail gas riser; A6(a6), second-stage biomass powder cyclone separator; A7(a7), biomass fuel molding device; A8(a8), biomass briquetted fuel assembly device; B(b), biomass briquetted fuel conveying unit; C(c), grouped briquetted biomass periodic pyrolysis unit, including: C1-C8 (c1-c8) briquetted biomass periodic pyrolysis device; DF(df), biomass pyrolysis volatile matter conveying system, including: D(d), D'(d'), D1-D8 (d1-d8), low-temperature pyrolysis fuel gas conveying channel; D f1 -D f6 (d f1 -d f6 ), Low-temperature pyrolysis gas channel valve; E(e), E'(e'), E1-E8(e1-e8), High-temperature pyrolysis flue gas conveying channel; E f1 -E f6 (e f1 -e f6 F0, high-temperature pyrolysis flue gas passage valve; F1 (f1), pyrolysis fuel gas tar pool; F2 (f2), tar pool output circulating water pump; F3 (f3), pyrolysis fuel gas tar pool tar input pipeline; F4 (f4), tar pump; F5 (f5), tar pipeline; G (g), biomass pyrolysis volatile matter energy recovery unit, including: G1 (g1), air inlet; G2 (g2), high-temperature combustion chamber; H (h), waste heat boiler, including: H1 (h1), waste heat boiler air inlet; H2 (h2), boiler furnace; I (i), tail gas purification unit, including: I1 (i1), I3 (i3), desulfurization device; I2 (i2), I4 (i4), dust removal device; I5 (i5), induced draft fan; I6 (i6), chimney; J (j), steam user, including multiple steam user units J1, J2, J3, J4 (j1, j2, j3, j4). Detailed Implementation

[0025] The present invention will now be further described with reference to the accompanying drawings.

[0026] Reference Figure 1A system for the periodic pyrolysis of briquetted biomass to co-produce charcoal and steam includes a biomass pretreatment unit, a biomass briquetted fuel conveying unit, a grouped briquetted biomass periodic pyrolysis unit, a biomass pyrolysis volatile matter conveying system, a biomass pyrolysis volatile matter energy recovery unit, a waste heat boiler, a tail gas purification unit, and a steam user unit. The biomass pretreatment unit is connected to the grouped briquetted biomass periodic pyrolysis unit and the biomass pyrolysis volatile matter energy recovery unit. The grouped briquetted biomass periodic pyrolysis unit is connected to the biomass pyrolysis volatile matter conveying system. The biomass pyrolysis volatile matter conveying system is connected to the biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler. The biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler are connected to the tail gas purification unit. The biomass briquetted fuel conveying unit is connected to the biomass pretreatment unit and the grouped briquetted biomass periodic pyrolysis unit. The waste heat boiler is also connected to the steam user unit.

[0027] In this embodiment, two systems operate in parallel and share a pyrolysis fuel gas tar pool F0. The system includes a biomass pretreatment unit A (a), a biomass briquetted fuel conveying unit B (b), a grouped briquetted biomass periodic pyrolysis unit C (c), a biomass pyrolysis volatile matter conveying system DF (df), a biomass pyrolysis volatile matter energy recovery unit G (g), a waste heat boiler unit H (h), a tail gas purification unit I (i), and a steam user unit J (j).

[0028] The biomass pretreatment unit A(a) includes, in sequence, a biomass crushing and screening device A1(a1), a biomass conveying device and a wet silo A2(a2), a biomass powder drying device A3(a3), a first-stage biomass powder cyclone separator A4(a4), a drying exhaust gas riser A5(a5), a second-stage biomass powder cyclone separator A6(a6), a biomass fuel molding device A7(a7), and a biomass briquette fuel assembly device A8(a8). In the biomass powder drying device A3(a3), the high-moisture-content wet biomass powder comes into direct contact with the high-temperature flue gas from the biomass pyrolysis volatile matter energy recovery unit G(g) for efficient heat exchange, evaporating the moisture and obtaining dry biomass powder. In the drying exhaust gas riser A5(a5), the drying exhaust gas, after being processed by the first-stage biomass powder cyclone separator A4(a4), is lifted and conveyed to the second-stage biomass powder cyclone separator A6(a6) to improve gas-solid separation efficiency.

[0029] The grouped biomass cyclic pyrolysis unit C(c) comprises multiple independently controllable biomass pyrolysis devices arranged in parallel (e.g., C1-C8, c1-c8). By precisely controlling the air supply and reaction temperature of each pyrolysis device, thermal decomposition chemical reactions occur under oxygen-deficient conditions. Within a complete cycle, each pyrolysis device sequentially produces low-temperature pyrolysis fuel gas, primarily composed of H2, CO, CH4, and tar organic matter, and high-temperature pyrolysis flue gas, primarily composed of CO2, ultimately yielding biomass char with a high fixed carbon content. Furthermore, the operation of each biomass pyrolysis device can be planned and organized according to changes in biomass feedstock supply or end-product demand, allowing multiple pyrolysis devices to operate simultaneously or partially, and enabling the reaction stages of each device to be staggered, achieving continuous and alternating operation of different pyrolysis reaction stages (low-temperature and high-temperature pyrolysis stages) at the system level.

[0030] The biomass pyrolysis volatile matter conveying system DF(df) includes independent low-temperature pyrolysis fuel gas conveying pipelines (D1-D8, d1-d8) and valves (D... f1 -D f6 , d f1 -d f6 ), and high-temperature pyrolysis flue gas conveying pipelines (E1-E8, e1-e8) and valves (E f1 -E f6 , e f1 -e f6 The system uses valve assemblies to precisely guide the volatiles of different qualities generated by each pyrolysis unit to the biomass pyrolysis volatile matter energy recovery unit G(g) or the waste heat boiler unit H(h), achieving precise energy allocation for either unit. The system also includes a tar tank F0 and a supporting tar recovery and circulation system (F1-F5) (f1-f5) for collecting and processing the tar formed by the cooling and condensation of low-temperature pyrolysis fuel gas.

[0031] The biomass pyrolysis volatile matter energy recovery unit G(g) is equipped with an air inlet (G1, g1) and a high-temperature combustion chamber (G2, g2). This unit receives low-temperature pyrolysis fuel gas, high-temperature pyrolysis flue gas, and fuel gas pyrolysis tar from the conveying system. Other supplementary fuels can also be used to generate more high-temperature flue gas through combustion in the high-temperature combustion chamber. The high-temperature flue gas is directly used in the biomass powder drying device A3(a3) of the biomass pretreatment unit A(a) to provide high-temperature heat for drying the wet biomass powder.

[0032] The waste heat boiler unit H(h) is equipped with an air inlet (H1, h1) and a boiler furnace (H2, h2). This unit receives heat from high-temperature pyrolysis flue gas from the conveying system and heats the water in the waste heat boiler by burning low-temperature pyrolysis fuel gas, generating high-temperature and high-pressure steam.

[0033] The exhaust gas purification unit I(i) includes a desulfurization device (I1, I3) (i1, i3), a dust removal device (I2, I4) (i2, i4), an induced draft fan I5 (i5), and a chimney I6 (i6). This unit purifies the exhaust gas emitted from the biomass pretreatment unit A(a) and the waste heat boiler unit H(h) to ensure that pollutants are discharged in compliance with standards.

[0034] The biomass briquette fuel conveying unit B(b) includes a biomass profile container, a biomass charcoal container, and hoisting equipment, which realizes automated loading of briquette biomass and automated handling of finished charcoal, thereby improving the transportation efficiency of biomass profiles and charcoal.

[0035] The steam user unit J(j) is used to receive and utilize the high-temperature, high-pressure steam generated by the waste heat boiler unit H(h). This unit includes a heat exchanger for exchanging heat between steam and a low-temperature medium. Through this heat exchanger, the thermal energy contained in the steam is supplied to the user in the form of hot water or steam. After releasing heat, the high-temperature, high-pressure steam condenses into water, which is then pumped back to the waste heat boiler unit for recycling.

[0036] Furthermore, the grouped biomass periodic pyrolysis unit C(c) achieves orderly output of pyrolysis volatiles at the system level through the alternating and periodic operation of multiple pyrolysis devices (C1-C8) (c1-c8). Specifically, through system scheduling, the chemical reactions of multiple pyrolysis devices alternate in sequence according to stages such as low-temperature pyrolysis to generate fuel gas, high-temperature pyrolysis to generate flue gas and charcoal, effectively avoiding interruptions in the production process and the output of pyrolysis volatiles; through the pipelines and valves set in the biomass pyrolysis volatiles conveying system DF(df), the low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas with different calorific values ​​and compositions are controlled to enter the biomass pyrolysis volatiles energy recovery unit G(g) and the waste heat boiler H(h) respectively, providing a guarantee for efficient energy recovery and utilization. A method for the periodic pyrolysis of shaped biomass to co-produce charcoal and steam, the method comprising the following steps: 1) In the biomass pretreatment unit A(a), the biomass raw material is first crushed and screened by the crushing and screening device A1(a1) to obtain wet biomass powder that meets the particle size requirements; then, the wet biomass powder is transported and temporarily stored in the wet silo A2(a2); next, the wet biomass powder is sent to the biomass powder drying device A3(a3), where it undergoes direct contact high-efficiency heat exchange with the high-temperature flue gas from the biomass pyrolysis volatile matter energy recovery unit G(g), and the moisture in the wet biomass powder is rapidly evaporated, thereby obtaining dry biomass powder. Finally, after releasing heat, the high-temperature flue gas experiences a decrease in temperature and an increase in humidity, becoming drying exhaust gas. This gas then passes sequentially through the first-stage biomass powder cyclone separator A4 (a4), the drying exhaust gas riser A5 (a5), and the second-stage biomass powder cyclone separator A6 (a6) for gas-solid separation. Finally, the dry biomass powder enters the biomass fuel molding device A7 (a7) and the biomass fuel molding assembly device A8 (a8), where it is densified and assembled into shaped biomass fuel with regular forms, providing qualified raw materials for subsequent periodic pyrolysis units. 2) Biomass briquettes are distributed via biomass briquette transfer unit B(b) to the individual units (C1-C8, c1-c8) of the grouped biomass briquetting periodic pyrolysis unit C(c). Through system regulation, multiple pyrolysis units operate in a periodic, alternating, and coordinated manner. Each pyrolysis unit sequentially undergoes two precisely controlled stages: first, a low-temperature pyrolysis stage (300-500℃, air equivalence ratio 0.05-0.15) generates low-temperature pyrolysis fuel gas primarily composed of H2, CO, CH4, and tar organic matter; then, a high-temperature pyrolysis stage (800-900℃, air equivalence ratio 0.20-0.25) generates high-temperature pyrolysis flue gas primarily composed of CO2 and N2, ultimately forming high-quality biomass char. By interleaving and connecting the reaction cycles of multiple units, the system achieves continuous output of two types of fuels with different calorific values ​​and volatile matter compositions. 3) The low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas are collected via independent conveying pipelines D1-D8 (d1-d8) and E1-E8 (e1-e8) into the low-temperature pyrolysis fuel gas conveying channel D (d) and the high-temperature pyrolysis flue gas conveying channel E (e), respectively, and controlled by the corresponding valves D. f1 -D f6 (d) f1 -d f6 E f1 -E f6 (e) f1 -e f6The gas is diverted and transported to the biomass pyrolysis volatile matter energy recovery unit G(g) and the waste heat boiler H(h). Simultaneously, the pyrolysis fuel gas tar generated during the cooling and condensation process is transported to the tar pool F0 via the low-temperature pyrolysis fuel gas transport channel D(d). The collected tar is then transported to the high-temperature combustion chamber of the biomass pyrolysis volatile matter energy recovery unit G(g), where it can be used as supplementary fuel for combustion, further realizing the recovery of biomass pyrolysis volatile matter energy. 4) The high-temperature, high-pressure saturated steam generated by the waste heat boiler unit H(h) is transported to the steam user unit J(j). In this unit, the steam is supplied to the user in the form of hot water or steam through a heat exchanger that exchanges heat between steam and a low-temperature medium. After the heat exchange is completed, the steam condenses into condensate, which is pumped back to the waste heat boiler unit H(h) for recycling, forming a closed working fluid cycle.

[0037] 5) The drying exhaust gas discharged from the biomass powder drying device A3 (a3) ​​of the biomass pretreatment unit A (a) and the combustion exhaust gas generated by the waste heat boiler unit H (h) enter the exhaust gas purification unit I (i) respectively. In unit I (i), the two exhaust gases are purified by passing through the desulfurization device (I1, I3) (i1,i3) and the dust removal device (I2, I4) (i2,i4) in sequence to remove pollutants such as sulfur dioxide and dust. The purified and qualified gas is discharged into the atmosphere through the chimney I6 (i6) under the action of the induced draft fan I5 (i5).

[0038] The working process of this embodiment is as follows: Biomass raw material (bamboo chips) first enters the biomass pretreatment unit A (a), and is crushed into powder with a particle size ≤10mm by the crushing and screening device A1 (a1). Then, it is sent to the wet material silo A2 (a2) for temporary storage by the conveying device. The moisture content of the bamboo chip powder in the wet material silo is about 25-45%. Subsequently, the wet bamboo chip powder is transported to the biomass powder drying device A3 (a3). During this process, the high-temperature flue gas (temperature about 600-700℃) from the biomass pyrolysis volatile matter energy recovery unit G (g) directly contacts the wet powder for heat exchange. The moisture in the wet powder evaporates rapidly, and finally dry bamboo chip powder with a moisture content ≤15% is obtained. The drying exhaust gas, carrying moisture and a small amount of fine powder, passes through the first-stage biomass powder cyclone separator A4 (a4) to capture coarse biomass powder particles with a diameter ≥200μm. Then, it is lifted by the drying exhaust gas riser A5 (a5) to the second-stage biomass powder cyclone separator A6 (a6) to further capture fine particles with a diameter ≥50μm. The biomass powder recovered after the two-stage separation is returned to the molding process for reuse, while the purified drying exhaust gas enters the exhaust gas purification unit I (i) for further treatment. The dried bamboo shavings powder is conveyed to the biomass fuel molding device A7 (a7) via a transport system. Under pressure of 15-20MPa and temperature of 120-150℃, it is extruded into square-section rod-shaped fuel with a side length of approximately 60mm and a length of approximately 300mm. Finally, it is placed into a biomass profile container via the biomass fuel molding assembly device A8 (a8), completing the biomass pretreatment process.

[0039] Biomass briquettes are fed into 16 pyrolysis units (C1-C8) of the grouped biomass briquette fuel transfer unit B(b) via container hoisting equipment. In actual production, the pyrolysis units operate periodically and alternately, utilizing the energy from the pyrolysis volatiles by transporting fuel from nearby locations. The operation mode of the pyrolysis unit includes: a single pyrolysis unit operates periodically. During operation, the reaction temperature is precisely controlled at 300-500℃ and the air equivalence ratio is 0.05-0.15 during the low-temperature pyrolysis stage. The biomass briquettes undergo low-temperature pyrolysis, generating low-temperature pyrolysis fuel gas with H2, CO, CH4 and tar organic matter as the main components. After the low-temperature pyrolysis is completed, the system switches to the high-temperature pyrolysis stage, controlling the temperature at 800-900℃ and the air equivalence ratio at 0.20-0.25. The remaining organic matter in the biomass briquettes undergoes deep thermal decomposition, and the carbon structure of the briquettes is densified, generating high-temperature pyrolysis flue gas mainly composed of CO2 and N2. After the high-temperature pyrolysis stage is completed, high-quality biomass char with a fixed carbon content ≥85%, a high calorific value ≥28MJ / kg, and a compressive strength ≥15MPa is obtained. The char containers generated after pyrolysis are taken out and stored using the hoisting equipment of the biomass briquette fuel transfer unit B(b). After the briquettes are removed from the container, the biomass briquettes are loaded into the pyrolysis unit using hoisting equipment, and the next production cycle begins.

[0040] Multiple pyrolysis units operate in a staggered, grouped manner, ensuring that different units are in the low-temperature and high-temperature pyrolysis stages respectively, achieving a continuous supply of pyrolysis volatiles. Each group of units outputs biomass pyrolysis volatiles and energy to the waste heat boiler H(h) or the biomass pyrolysis volatile energy recovery unit G(g) according to proximity, ensuring short-distance transport of volatiles to reduce heat loss during transport. In this embodiment, pyrolysis units C1-C4 (c1-c4) are arranged in groups around the waste heat boiler unit H(h), and pyrolysis units C5-C8 (c5-c8) are arranged in groups around the biomass pyrolysis volatile energy recovery unit G(g). For each group of pyrolysis units, each unit can be in a different operating stage. For example, pyrolysis units C1-C4 (c1-c4) can be in the low-temperature pyrolysis stage and the high-temperature pyrolysis stage respectively, and alternately supply low-temperature pyrolysis volatiles and high-temperature pyrolysis volatiles to the waste heat boiler H (h). Pyrolysis units C1-C4 (c1-c4) can all operate simultaneously, or only some (more than 2 units) can be in operation as needed. Pyrolysis units C5-C8 (c5-c8) can be in the low-temperature pyrolysis stage and the high-temperature pyrolysis stage respectively, and alternately supply low-temperature pyrolysis volatiles and high-temperature pyrolysis volatiles to the biomass pyrolysis volatiles energy recovery unit G (g). Pyrolysis units C5-C8 (c5-c8) can all operate simultaneously, or only some (more than 2 units) can be in operation as needed.

[0041] In the grouped biomass periodic pyrolysis unit C(c), the biomass pyrolysis volatiles generated by the pyrolysis unit are directionally transported and guided through the biomass pyrolysis volatiles conveying system DF(df), which includes pipelines, valves, and tar treatment facilities. The low-temperature pyrolysis fuel gas generated by the pyrolysis unit is transported through conveying pipelines D1-D8 (d1-d8), D(d), and D'(d'), and passes through pipeline valve D... f1 -D f6 (d f1 -d f6 ) Controlling the flow direction. For example, in actual operation, when pyrolysis units C1 and C2 (c1, c2) are in the low-temperature pyrolysis stage and C3 and C4 (c3, c4) are in the high-temperature pyrolysis stage, the low-temperature pyrolysis fuel gas generated by C1 and C2 (c1, c2) enters pipe D (d) through pipes D1 and D2 (d1, d2) respectively, and valve D f1 (d) f1 Open valve D f2 D f3 (d) f2 d f3 The valve E is closed, thus transporting the low-temperature pyrolysis fuel gas generated by C1 and C2 (c1, c2) to the waste heat boiler H (h); the high-temperature pyrolysis flue gas generated by C3 and C4 (c3, c4) enters pipeline E (e) through pipelines E3 and E4 (e3, e4) respectively, and valve E f1 E f2 (e) f1 e f2 Open valve E f3 (e) f3 The valve D is closed, thus transporting the high-temperature pyrolysis flue gas to the waste heat boiler H (h). Simultaneously, when pyrolysis units C5 and C6 (c5, c6) are in the low-temperature pyrolysis stage and C7 and C8 (c7, c8) are in the high-temperature pyrolysis stage, the low-temperature pyrolysis fuel gas generated by C5 and C6 (c5, c6) enters pipelines D and D' (d, d') respectively through pipelines D5 and D6 (d5, d6), closing valve D. f3 D f4 D f6 (d) f3 d f4 d f6 All valves are closed, thus transporting the low-temperature pyrolysis fuel gas generated by C5 and C6 (c5, c6) to the energy recovery unit G (g); the high-temperature pyrolysis flue gas generated by C7 and C8 (c7, c8) enters pipelines E and E' (e, e') respectively through pipelines E7 and E8 (e7, e8), and valve E is closed. f3 E f5 E f6 (e) f3 e f5 ef6 Open valve E f4 (e) f4 This process transports the high-temperature pyrolysis flue gas generated by C7 and C8 (c7, c8) to the energy recovery unit G (g). During the transport of the low-temperature pyrolysis fuel gas, the fuel gas temperature decreases due to natural cooling. The high molecular weight tar-like volatiles and water vapor in the fuel gas condense from the gaseous state to the liquid state. The liquid tar and water flow in the sloping pipe D (d) from the waste heat boiler H (h) side (which has a higher pipe height) to the pyrolysis fuel gas tar pool F0 side (which has a lower pipe height) based on the principle of gravity. F0 contains a mixture of liquid water and tar, with the denser liquid water at the bottom and the less dense tar at the top. The lower part of F0 is equipped with a pipe connected to the inlet of the circulating water pump F1 (f1) of the tar pool output. Under the action of F1 (f1), the water in the lower part of F0 is transported to pipe D (d) through the circulating water pipe F2 (f2) of the tar pool output. In pipe D (d), the circulating water accelerates the flow of condensate and condensed tar, and enters the pyrolysis fuel gas tar pool F0 through the tar input pipe F3 (f3) of the pyrolysis fuel gas tar pool. The tar in F0 has a high calorific value and can play a role in storing biomass energy. When the energy demand of the system energy recovery unit G (g) increases, the tar stored in the upper part of the tar pool is transported through the tar pipe F5 (f5) to the tar burner of the biomass pyrolysis volatile matter energy recovery unit G (g) by the tar pump F4 (f4) for combustion as supplementary fuel.

[0042] The biomass pyrolysis volatile matter energy recovery unit G(g) receives low-temperature pyrolysis fuel gas, high-temperature pyrolysis flue gas, and tar transported from the tar pool from C5-C8 (c5-c8). A small amount of other fuels can be added to the combustion of the fuels as needed for drying wet biomass. The fuels are fully mixed and burned in the high-temperature combustion chamber with the air introduced through the air inlet G1 (g1) to generate high-temperature flue gas at 600-700°C. This high-temperature flue gas is directly introduced into the biomass powder drying device A3 (a3) ​​to provide a heat source for drying the wet biomass powder. After heat exchange, the flue gas temperature drops to 120-150°C. It then passes through the first-stage biomass powder cyclone separator A4 (a4), the drying tail gas riser A5 (a5), and the second-stage biomass powder cyclone separator A6 (a6) to achieve coarse biomass powder separation, further cooling and temperature reduction, and fine biomass powder separation. Finally, it enters the tail gas purification unit I(i) for purification treatment. Waste heat boiler unit H(h) receives low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas from C1-C4 (c1-c4). It uses the heat released by the combustion of fuel gas in the furnace and the heat from the high-temperature pyrolysis flue gas to heat the water in the boiler into high-temperature and high-pressure steam (temperature 200-350℃, pressure 0.2-1.2MPa). The steam is transported to steam user unit J(j) through pipelines. In the heat exchanger, it exchanges heat with the low-temperature medium at the user end to meet the heat demand in the form of hot water or steam. The condensate after heat exchange is pumped back to waste heat boiler unit H(h) for recycling.

[0043] The exhaust gas purification unit I(i) purifies two exhaust gases from the biomass pretreatment unit A(a) and the waste heat boiler H(h): the exhaust gas from the waste heat boiler H(h) first enters the semi-dry desulfurization unit I1(i1) to remove SO2, with a desulfurization efficiency ≥95%, and then passes through the bag filter I2(i2) to remove particulate matter, with a dust removal efficiency ≥99.5%; the exhaust gas from the pretreatment unit A(a) passes through the semi-dry desulfurization unit I3(i3) and the bag filter I4(i4) for desulfurization and dust removal purification. After the two sets of purified exhaust gases are combined, they are discharged into the atmosphere through the chimney I6(i6) driven by the induced draft fan I5(i5).

[0044] This embodiment presents a system and method for the periodic pyrolysis of shaped biomass to co-produce char and steam, which has advantages such as large-scale biomass utilization, high energy efficiency, economic and environmental protection, and co-production of high-value biomass char and steam.

[0045] The embodiments described in this specification are merely examples of implementations of the inventive concept and are for illustrative purposes only. The scope of protection of this invention should not be considered limited to the specific forms described in these embodiments; rather, it extends to equivalent technical means conceived by those skilled in the art based on the inventive concept.

Claims

1. A system for the periodic pyrolysis of shaped biomass to co-produce charcoal and steam, characterized in that, The system includes a biomass pretreatment unit, a biomass briquette fuel conveying unit, a grouped briquette biomass periodic pyrolysis unit, a biomass pyrolysis volatile matter conveying system, a biomass pyrolysis volatile matter energy recovery unit, a waste heat boiler, a tail gas purification unit, and a steam user unit. The biomass pretreatment unit is connected to the grouped briquette biomass periodic pyrolysis unit and the biomass pyrolysis volatile matter energy recovery unit. The grouped briquette biomass periodic pyrolysis unit is connected to the biomass pyrolysis volatile matter conveying system. The biomass pyrolysis volatile matter conveying system is connected to the biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler. The biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler are connected to the tail gas purification unit. The biomass briquette fuel conveying unit is connected to the biomass pretreatment unit and the grouped briquette biomass periodic pyrolysis unit. The waste heat boiler is also connected to the steam user unit.

2. The system for the periodic pyrolysis and co-production of charcoal and steam from shaped biomass as described in claim 1, characterized in that, The material pretreatment unit is used to crush, screen, dry and shape biomass raw materials, including a biomass crushing device, a screening device, a conveying device, a wet material silo, a drying device, a biomass powder separator, a dry material silo, a biomass fuel shaping and shaped fuel assembly device connected in sequence. The group-type molten biomass periodic pyrolysis unit utilizes multiple sets of collaboratively working biomass pyrolysis reactors to thermally decompose molten biomass into biomass char. It sequentially generates low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas containing energy-rich volatiles according to a certain cycle. The unit includes multiple molten biomass periodic pyrolysis reactors, where the molten biomass undergoes an oxygen-deficient pyrolysis chemical reaction under controlled air flow and pyrolysis temperature conditions. Each biomass pyrolysis reactor periodically generates low-temperature pyrolysis combustible volatiles, primarily composed of H2, CO, CH4, water vapor, and tar organic matter, and non-combustible high-temperature pyrolysis flue gas volatiles, primarily composed of CO2 and N2, ultimately forming char with carbon as the main component. The biomass pyrolysis volatile matter conveying system is used to convey low-temperature pyrolysis fuel gas generated from the pyrolysis of shaped biomass, tar generated from the cooling of low-temperature pyrolysis fuel gas, and high-temperature pyrolysis flue gas. It includes low-temperature pyrolysis fuel gas conveying pipelines and valves, high-temperature pyrolysis flue gas conveying pipelines and valves, pyrolysis fuel gas tar pools, as well as tar pipelines, tar pumps, circulating water pipelines, and circulating water pumps.

3. The system for the periodic pyrolysis and co-production of charcoal and steam from shaped biomass as described in claim 2, characterized in that, The biomass pyrolysis volatile matter energy recovery unit is used to receive a portion of the biomass pyrolysis volatile matter and use the recovered volatile matter energy to perform drying pretreatment on the biomass powder, including a high-temperature combustion chamber and an air passage. The waste heat boiler unit is used to receive a portion of the biomass pyrolysis volatiles and convert the recovered volatile energy into high-temperature steam, including a boiler furnace and an air inlet; The exhaust gas purification unit is used to remove pollutants such as sulfur and dust from the exhaust gas of the waste heat boiler and biomass pretreatment unit, including a desulfurization device, a dust removal device, an induced draft fan and a chimney. The biomass briquette fuel conveying unit is used to place briquette biomass into the pyrolysis unit and to remove and place biomass char from the pyrolysis unit when pyrolysis is completed, including biomass profile container, biomass char container, and container hoisting equipment; The steam user unit is used for production or domestic use of steam generated by the waste heat boiler, and includes a heat exchanger for exchanging heat between steam and a low-temperature medium.

4. The system for the periodic pyrolysis and co-production of charcoal and steam from shaped biomass as described in claim 2, characterized in that, In the biomass powder drying device of the biomass pretreatment unit, wet biomass powder with high moisture content comes into contact with high-temperature flue gas from the biomass pyrolysis volatile matter energy recovery unit. After the moisture in the wet biomass powder evaporates and enters the flue gas, dry biomass is produced. The water vapor content of the high-temperature flue gas increases and the temperature decreases. In the grouped biomass periodic pyrolysis unit, the reaction cycles of each biomass periodic pyrolysis device alternate, and the reaction stage of the biomass in each pyrolysis device can be flexibly adjusted. All pyrolysis devices in the grouped biomass periodic pyrolysis unit can operate simultaneously, or only some devices can operate. In the biomass pyrolysis volatile matter conveying system, the low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas of each biomass periodic pyrolysis unit enter separate conveying channels and are connected through these channels. During operation, each biomass periodic pyrolysis unit is connected to the low-temperature pyrolysis fuel gas channel and the high-temperature pyrolysis flue gas channel. Both the low-temperature pyrolysis fuel gas channel and the high-temperature pyrolysis flue gas channel are equipped with valves to control the gas delivery to the energy recovery unit and the waste heat boiler unit. The low-temperature pyrolysis fuel gas channel uses gravitational potential difference and circulating water to transport the tar and condensate generated from the cooling of the pyrolysis fuel gas in the channel to the pyrolysis fuel gas tar pool.

5. A system for the periodic pyrolysis and co-production of charcoal and steam from shaped biomass as described in claim 3, characterized in that, The biomass pyrolysis volatile matter energy recovery unit uses one or more of the following: low-temperature biomass pyrolysis fuel gas, biomass pyrolysis fuel gas tar, high-temperature flue gas generated from the combustion of other supplementary fuels in the high-temperature combustion chamber, or high-temperature biomass pyrolysis flue gas, to dry the wet biomass in the biomass powder drying device in the biomass pretreatment unit. The waste heat boiler unit uses one or more of the following: biomass low-temperature pyrolysis fuel gas, high-temperature flue gas generated from the combustion of other supplementary fuels, or biomass high-temperature pyrolysis flue gas, to heat water and generate high-temperature, high-pressure steam. The exhaust gas purification unit performs desulfurization and dust removal purification treatments on the flue gas from the waste heat boiler unit and the exhaust gas from the biomass pretreatment unit, respectively.

6. The system for the periodic pyrolysis and co-production of charcoal and steam from shaped biomass as described in claim 3, characterized in that, The biomass briquette fuel conveying unit can accurately place biomass briquette containers into each biomass periodic pyrolysis unit or remove biomass char containers from the biomass periodic pyrolysis unit and place them at the storage location.

7. A method for a system for the periodic pyrolysis and co-production of charcoal and steam from biomass as described in claim 1, characterized in that, The method includes the following steps: 1) In the biomass pretreatment unit, after the biomass raw materials are crushed, screened, transported and stored, they enter the drying device. The high-temperature flue gas provided by the biomass pyrolysis volatile matter energy recovery unit is used to dry the wet biomass powder to produce dry biomass powder, which is then processed into biomass briquettes fuel by the molding device. 2) Biomass briquettes are fed into the grouped briquetted biomass periodic pyrolysis unit through the biomass briquette fuel conveying unit. In the pyrolysis reactor, an oxygen-deficient thermal decomposition chemical reaction occurs, periodically generating low-temperature pyrolysis combustible volatiles mainly composed of H2, CO, CH4, a small amount of water vapor and tar organic matter, and non-combustible high-temperature pyrolysis flue gas volatiles mainly composed of CO2 and N2, and finally forming biomass char mainly composed of carbon elements. 3) Low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas are transported to the biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler unit respectively through the biomass pyrolysis volatile matter conveying system. Among them, a portion of the low-temperature pyrolysis fuel gas and the tar produced by its cooling, as well as the high-temperature pyrolysis flue gas, enter the biomass pyrolysis volatile matter energy recovery unit. In the high-temperature combustion chamber, a large amount of high-temperature flue gas is generated through combustion. The flue gas is then passed into the biomass powder drying device of the biomass pretreatment unit to dry the wet biomass powder. Another portion of the low-temperature pyrolysis fuel gas and high-temperature pyrolysis flue gas enter the waste heat boiler unit, where they are combusted and water is heated to generate high-temperature and high-pressure steam. The conveyance of low-temperature pyrolysis fuel gas, high-temperature pyrolysis flue gas, and pyrolysis fuel gas tar to the biomass pyrolysis volatile matter energy recovery unit and the waste heat boiler unit is flexibly controlled through the low-temperature pyrolysis gas channel and valves, the high-temperature pyrolysis flue gas channel and valves, and the tar pipeline and tar pump. 4) The high-temperature and high-pressure steam generated by the waste heat boiler unit is transported to the steam user unit, where heat is exchanged through a heat exchanger and supplied to the user in the form of hot water or steam. After releasing heat, the high-temperature and high-pressure steam becomes condensate and is transported back to the waste heat boiler through a condensate pump. 5) The exhaust gas generated by the biomass pretreatment unit and the waste heat boiler unit enters the exhaust gas purification unit, and after desulfurization and dust removal purification treatment, it is discharged through the chimney.

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