Green low-carbon biomass coupling fused salt energy storage methanol preparation system

Abstract

The invention provides a green low-carbon biomass coupling fused salt energy storage methanol preparation system, and belongs to the field of methanol preparation systems. The problem that methanol purge gas is released and residual biomass gas is generated and needs to be treated in the process of preparing methanol through biomass gasification is solved. One part of new energy electricity is used for electrolyzing water, the other part of new energy electricity serves as abandoned electricity to enter a fused salt electric heater, hydrogen generated by electrolyzing water enters a catalytic synthesis tower, oxygen is used for biomass gasification, generated carbon monoxide, hydrogen and carbon dioxide enter the catalytic synthesis tower, and methanol is synthesized in the catalytic synthesis tower. Biomass, redundant biomass gas and formaldehyde purge gas enter the high-temperature and high-pressure biomass fluidized bed boiler, then superheated steam generated by the high-temperature and high-pressure biomass fluidized bed boiler and part of steam serve as a catalytic temperature heat source for methanol production, the remaining steam enters the power generation system to be used for power generation, and stable power supply of the whole system is guaranteed. And the generated high-temperature and high-pressure steam is used for power generation to improve the unit efficiency.

Description

Technical Field

[0001] The present invention belongs to the field of methanol preparation systems, and in particular relates to a green low-carbon biomass coupled molten salt energy storage methanol production system. Background Art

[0002] At present, the scale of new energy is increasing day by day, but new energy is volatile and unstable. In many methanol-producing power plants, the mainstream route is oxygen-enriched biomass gasification and electrolysis of water using electricity from new energy sources. The oxygen from electrolysis enters the oxygen-enriched biomass gasifier, biomass is gasified, and an entrained flow bed is used to gasify biomass. The electricity from new energy sources is used to electrolyze water to produce hydrogen and oxygen. The oxygen enters the entrained flow bed to gasify the biomass entrained flow bed. After purification and other treatments, carbon monoxide, hydrogen and carbon dioxide are finally produced, which are then combined with the hydrogen produced by electrolysis, and finally methanol is synthesized under the action of a catalyst at about 300°C.

[0003] The existing technology has the following problems: the process of biomass gasification to methanol releases methanol relaxation gas and produces residual biomass gas, which needs to be treated. At the same time, this process also requires a temperature of about 300°C to maintain the activity of the catalyst during the startup phase, and a heat source is required to heat the catalyst to a specified temperature. At the same time, the electricity from new energy sources is used to electrolyze water. The large amount of electricity from new energy sources wastes resources, and the entire system is costly and economical. Summary of the invention

[0004] In view of this, in order to solve the problem of releasing methanol purge gas and generating excess biomass gas during biomass gasification to produce methanol, which needs to be dealt with, the present invention proposes a green and low-carbon biomass coupled molten salt energy storage methanol production system.

[0005] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a green and low-carbon biomass coupled molten salt energy storage methanol production system, comprising two high-temperature and high-pressure biomass fluidized bed boilers, a molten salt system and two steam generator systems. In the methanol production process, the methanol relaxation gas generated and the excess biomass gas produced by biomass gasification to produce methanol are merged into the main pipe and sent to the two high-temperature and high-pressure biomass fluidized bed boilers together. The molten salt heat storage system comprises a low-temperature molten salt tank, a molten salt electric heater and a high-temperature molten salt tank connected in sequence, and the abandoned electricity of new energy electricity enters the molten salt electric heater. The steam generator system comprises a superheater, an evaporator-starter and a preheater. The high-temperature molten salt tank is connected to the superheater of one of the steam generator systems, and the low-temperature molten salt tank is connected to the preheater of the above-mentioned steam generator system. The two high-temperature and high-pressure biomass fluidized bed boilers and the two steam generator systems are connected to the power generation system, and are also connected to the catalytic synthesis tower.

[0006] Furthermore, two high-temperature and high-pressure biomass fluidized bed boilers produce steam with parameters of 9.8MPa / 540℃ for consuming biomass energy.

[0007] Furthermore, the low-temperature desalted water is heated by two steam generator systems and becomes 9.8MPa / 540℃ superheated steam, which is then combined with the steam generated by the high-temperature and high-pressure biomass fluidized bed boiler and flows into the main pipe to enter the catalytic synthesis tower, providing a stable steam heat source for the methanol system startup phase.

[0008] Furthermore, part of the steam produced by the two steam generator systems is used as a catalytic temperature heat source for producing methanol, and the other part is used to generate electricity, ensuring a stable power supply for the entire system.

[0009] Furthermore, the molten salt electric heater uses the electricity from abandoned wind and solar power to heat the 290℃ low-temperature molten salt into 565℃ high-temperature molten salt for storage.

[0010] Furthermore, high-temperature molten salt is extracted from the high-temperature molten salt storage tank, and the low-temperature molten salt after heat exchange in the superheater, evaporator, and preheater enters the low-temperature molten salt storage tank.

[0011] Furthermore, when the molten salt system is started, the pure storage mode is turned on, the molten salt electric heater is turned on for preheating, and then the low-temperature molten salt is pumped into the molten salt electric heater for heating through the low-temperature molten salt tank, and then enters the high-temperature molten salt tank for storage. When the molten salt heat storage exceeds the capacity of the two steam generator systems in the heat release stage, redundant reserves are stored.

[0012] Furthermore, when a biomass boiler is running at full load, running a steam generator system can meet the total amount of superheated steam in the system outlet section. In the system, the biomass boiler and the steam generator system serve as backup for each other and can operate continuously and stably.

[0013] Furthermore, when one biomass boiler is operated at 70% load, two steam generator systems are operated at reduced load to meet the total amount of superheated steam at the system outlet section. In the system, one biomass boiler is kept as a standby and can operate continuously and stably.

[0014] Furthermore, when the two biomass boilers are completely stopped, the two steam generator systems are operated at full load to meet the total amount of superheated steam at the system outlet section, but the steam generator systems need to operate intermittently.

[0015] Compared with the prior art, the green low-carbon biomass coupled molten salt energy storage methanol production system described in the present invention has the following beneficial effects:

[0016] (1) The present invention utilizes a biomass boiler to consume biomass and achieve zero carbon emissions. The methanol off-gas generated in the methanol production process and the excess biomass gas produced by biomass gasification to produce methanol are processed through a biomass boiler, which can reduce the waste gas disposal costs and reduce the use of biomass.

[0017] (2) In addition to the electricity used for water electrolysis, the surplus electricity from new energy sources can be used to heat molten salt using electric heaters and stored in the form of heat, so that the electricity can be effectively utilized. At the same time, during the heat release stage of the hot molten salt, it can also provide a stable steam heat source for the methanol system startup phase to ensure catalyst activity.

[0018] (3) When the methanol system is operating normally, the heat released by the methanol reaction can be used to heat the low-temperature desalted water. In addition, when there is a lot of electricity, it can also replace part of the biomass boiler load. The steam generated by the biomass boiler and the molten salt heat release can be used as backup to ensure the efficient, safe and stable operation of the methanol production system, laying the foundation for promoting large-scale methanol production. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0020] Figure 1 A schematic diagram of the green low-carbon biomass coupled molten salt energy storage methanol production system of the present invention; DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0022] See also Figure 1 This embodiment describes a green and low-carbon biomass coupled molten salt energy storage methanol production system, including two high-temperature and high-pressure biomass fluidized bed boilers, a molten salt system and two steam generator systems. In the methanol production process, the methanol relaxation gas produced and the excess biomass gas produced by biomass gasification to produce methanol are combined into a main pipe and sent together into two high-temperature and high-pressure biomass fluidized bed boilers. The molten salt heat storage system includes a low-temperature molten salt tank, a molten salt electric heater and a high-temperature molten salt tank connected in sequence. The abandoned electricity of new energy electricity enters the molten salt electric heater. The steam generator system includes a superheater, an evaporator-starter and a preheater. The high-temperature molten salt tank is connected to the superheater of one of the steam generator systems, and the low-temperature molten salt tank is connected to the preheater of the above-mentioned steam generator system. The two high-temperature and high-pressure biomass fluidized bed boilers and the two steam generator systems are connected to the power generation system, and are also connected to the catalytic synthesis tower.

[0023] Part of the new energy electricity is used for water electrolysis, and part of it is used as abandoned electricity to enter the molten salt electric heater. The hydrogen produced by water electrolysis enters the catalytic synthesis tower, and the oxygen is used for biomass gasification. The carbon monoxide, hydrogen and carbon dioxide produced enter the catalytic synthesis tower, and methanol is synthesized in the catalytic synthesis tower. The biomass, excess biomass gas and formaldehyde release gas enter the high-temperature and high-pressure biomass fluidized bed boiler, and then the superheated steam generated by the high-temperature and high-pressure biomass fluidized bed is used as a catalytic temperature heat source for the production of methanol. The remaining steam enters the power generation system for power generation, ensuring the stable power supply of the entire system. The high-temperature and high-pressure steam produced is used for power generation to improve the efficiency of the unit.

[0024] The present invention constructs two high-temperature and high-pressure biomass fluidized bed boilers, and the steam parameters generated are 9.8MPa / 540℃, which are used to consume biomass energy. Two steam generator systems are set up to heat the low-temperature desalted water to superheated steam of 9.8MPa / 540℃, and the steam generated by the high-temperature and high-pressure biomass fluidized bed boiler is merged into the main pipe.

[0025] Low temperature desalted water is water from the deaerator in the high temperature and high pressure biomass fluidized bed boiler.

[0026] The above-mentioned low-temperature desalted water is heated by the feed water heater, preheater, evaporator-steam drum and superheater to become 9.8MPa / 540℃ superheated steam. The temperature of the low-temperature desalted water must be higher than the melting point of the molten salt plus 20℃ to ensure that the molten salt will not solidify during heat exchange with the molten salt, affecting the safety of the use of the molten salt.

[0027] In the methanol production process, methanol relaxation gas (CO, H2, etc.) and excess biomass gas from biomass gasification to produce methanol will be generated, which can be combined into a main pipe and sent into a high-temperature and high-pressure biomass fluidized bed boiler together.

[0028] The molten salt electric heater uses electricity from abandoned wind and solar power to heat 290℃ low-temperature molten salt into 565℃ high-temperature molten salt, store it, and release heat using the high-temperature molten salt storage tank.

[0029] In the system, it is necessary to ensure that the two steam generator systems and the two high-temperature and high-pressure biomass circulating fluidized bed boilers produce the same steam.

[0030] The molten salt system includes a molten salt electric heater, a high-temperature molten salt storage tank and a low-temperature molten salt storage tank. The steam generator system includes a preheater, an evaporator-steam drum and a superheater. The high-temperature molten salt is extracted from the high-temperature molten salt storage tank, and the low-temperature molten salt enters the low-temperature molten salt storage tank after heat exchange in the superheater, evaporator and preheater.

[0031] When the molten salt system is started, the pure storage mode is turned on, the molten salt electric heater is turned on for preheating, and the low-temperature molten salt is then pumped into the molten salt electric heater for heating through the low-temperature molten salt tank, and then into the high-temperature molten salt tank for storage. When the molten salt heat storage exceeds the capacity of the two steam generator systems in the heat release stage, redundant storage is performed.

[0032] The heat released by the reaction catalyst of the methanol production system in normal operation is used to heat the low-temperature desalted water at 150-170°C, and then the steam from the power generation system of the biomass circulating fluidized bed unit is used to heat the low-temperature desalted water to 270°C.

[0033] It is necessary to ensure that the power of the molten salt electric heater is equal to the amount of steam generated by the heat release system, and the electric power of the power supply section of the electric heater can ensure the safe and stable operation of the system.

[0034] Each group of molten salt electric heaters uses a safe and stable 10MW electromagnetic molten salt electric heater, and the power fluctuation range of the electromagnetic molten salt electric heater is 2 to 10MW. Different voltage levels such as 6 / 10kV are designed according to the on-site power supply conditions, with high efficiency (>97%), and the appropriate number of electromagnetic molten salt heaters is selected according to the remaining wind and solar power abandonment.

[0035] The minimum operating load of the steam generator system is set to 30%. In order to realize the backup of the biomass boiler and the steam generator system, the load range of the biomass boiler must be 70%-100% in the entire system to ensure the safe and reliable operation of the biomass unit coupled with the molten salt heat storage system.

[0036] In order to ensure the continuous and stable operation of the system, the storage and release mode is adopted.

[0037] When a biomass boiler is running at full load, one steam generator system can be operated to meet the total amount of superheated steam at the outlet of the system. In the system, the biomass boiler and the steam generator system serve as backup for each other and can operate continuously and stably.

[0038] When one biomass boiler is operated at a reduced load of 70%, two steam generator systems can be operated at a reduced load to meet the total amount of superheated steam at the system outlet. In the system, one biomass boiler is kept as a standby and can operate continuously and stably.

[0039] When the two biomass boilers are completely stopped, the two steam generator systems can be operated at full load to meet the total amount of superheated steam in the system outlet section, but the steam generator systems need to operate intermittently.

[0040] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A green low-carbon biomass coupled molten salt energy storage methanol production system, characterized by: It includes two high-temperature and high-pressure biomass fluidized bed boilers, a molten salt system and two steam generator systems. In the methanol production process, the methanol relaxation gas and the excess biomass gas produced by biomass gasification to produce methanol are combined into a main pipe and sent to the two high-temperature and high-pressure biomass fluidized bed boilers together. The molten salt heat storage system includes a low-temperature molten salt tank, a molten salt electric heater and a high-temperature molten salt tank connected in sequence. The abandoned electricity of new energy electricity enters the molten salt electric heater. The steam generator system includes a superheater, an evaporator-starter and a preheater. The high-temperature molten salt tank is connected to the superheater of one of the steam generator systems, and the low-temperature molten salt tank is connected to the preheater of the above-mentioned steam generator system. The two high-temperature and high-pressure biomass fluidized bed boilers and the two steam generator systems are connected to the power generation system and are also connected to the catalytic synthesis tower.

2. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 1 is characterized by: The high-temperature and high-pressure biomass fluidized bed boiler produces steam with parameters of 9.8MPa / 540℃, which is used to consume biomass energy.

3. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 2 is characterized by: The low-temperature desalted water in the deaerator of the high-temperature and high-pressure biomass fluidized bed boiler is heated by the feed water heater, preheater, evaporator-steam drum and superheater to become superheated steam with steam parameters of 9.8MPa / 540℃, which is then merged into the main pipe together with the steam generated by the high-temperature and high-pressure biomass fluidized bed boiler.

4. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 1 is characterized by: The molten salt electric heater uses the electricity from abandoned wind and solar power to heat 290℃ low-temperature molten salt into 565℃ high-temperature molten salt for storage.

5. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 1 is characterized by: High-temperature molten salt is extracted from the high-temperature molten salt storage tank, and the low-temperature molten salt after heat exchange in the superheater, evaporator and preheater enters the low-temperature molten salt storage tank.

6. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 1 is characterized by: The steam generated by the two steam generator systems is used partly as a catalytic temperature heat source for producing methanol, and the other part is used to generate electricity to ensure stable power supply for the entire system.

7. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 1 is characterized by: When the molten salt system is started, the pure storage mode is turned on, the molten salt electric heater is turned on for preheating, and the low-temperature molten salt is then pumped into the molten salt electric heater for heating through the low-temperature molten salt tank's low-temperature molten salt pump, and then into the high-temperature molten salt tank for storage. When the molten salt heat storage exceeds the capacity of the two steam generator systems in the heat release stage, redundant reserves are stored.

8. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 1 is characterized by: When one biomass boiler is running at full load, running one steam generator system can meet the total amount of superheated steam at the system outlet. In the system, the biomass boiler and steam generator system serve as backup for each other and can operate continuously and stably.

9. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 1 is characterized by: When one biomass boiler is operated at 70% load, two steam generator systems are operated at reduced load to meet the total amount of superheated steam at the system outlet section. In the system, one biomass boiler is kept as a standby and can operate continuously and stably.

10. The green low-carbon biomass coupled molten salt energy storage methanol production system according to claim 1, characterized in that: When the two biomass boilers are completely stopped, the two steam generator systems are operated at full load to meet the total amount of superheated steam in the system outlet section, but the steam generator systems need to operate intermittently.

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