Green low-carbon biomass coupling molten salt energy storage methanol system

Abstract

The present application provides a kind of green low-carbon biomass coupling molten salt energy storage system for preparing methanol, belongs to the field of methanol preparation system.The problem of methanol release gas and surplus biomass gas produced in the process of biomass gasification for preparing methanol needs to be treated is solved.New energy electricity is partly used for electrolysis of water, and partly as abandoned electricity into molten salt electric heater.Hydrogen produced by electrolysis of water enters catalytic synthesis tower, and oxygen is used for biomass gasification.Carbon monoxide, hydrogen and carbon dioxide produced enter catalytic synthesis tower, and methanol is synthesized in catalytic synthesis tower.Biomass, surplus biomass gas and formaldehyde release gas enter high-temperature high-pressure biomass fluidized bed boiler, and then superheated steam produced by high-temperature high-pressure biomass fluidized bed is used as a catalytic temperature heat source for producing methanol, and the remaining steam enters a power generation system for power generation to ensure stable power supply of the entire system.The high-temperature high-pressure steam produced for power generation can improve the unit efficiency.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of methanol preparation system, and particularly relates to a green low-carbon biomass coupling molten salt energy storage methanol preparation system. BACKGROUND

[0002] At present, the scale of new energy is increasing, but new energy has volatility and instability. Many methanol production power plants adopt the mainstream route of oxygen-enriched biomass gasification and new energy electricity for water electrolysis. Oxygen generated by electrolysis enters the oxygen-enriched biomass gasification furnace, biomass gasification is carried out in a gas flow bed, hydrogen and oxygen are generated by electrolyzing water using new energy electricity, oxygen enters the gas flow bed to make the biomass gas flow bed gasification, and finally methanol is synthesized under the action of a catalyst at about 300 DEG C after purification and other treatments.

[0003] However, the prior art has the following problems: methanol purge gas and residual biomass gas are released during the process of biomass gasification for methanol production, and need to be treated. At the same time, the process also needs to maintain the catalyst activity at about 300 DEG C during the start-up stage, and a heat source is needed to heat the catalyst to a specified temperature, and new energy electricity is used for water electrolysis. The new energy electricity is excessive, resources are wasted, the whole system has high cost and poor economy. SUMMARY

[0004] Therefore, the present application provides a green low-carbon biomass coupling molten salt energy storage methanol preparation system to solve the problem of methanol purge gas and residual biomass gas released during the process of biomass gasification for methanol production.

[0005] To achieve the above-mentioned purpose, the present application adopts the following technical scheme: a green low-carbon biomass coupling molten salt energy storage methanol preparation system, comprising two high-temperature high-pressure biomass fluidized bed boilers, a molten salt system and two sets of steam generator systems. In the methanol production process, methanol purge gas and excess biomass gas for methanol production by biomass gasification are combined into a mother pipe and sent into the two high-temperature high-pressure biomass fluidized bed boilers. 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. The abandoned electricity of new energy is input into the molten salt electric heater. The steam generator system comprises a superheater, an evaporator-heat preservation device and a preheater. The high-temperature molten salt tank is connected with the superheater of one set of the steam generator system, and the low-temperature molten salt tank is connected with the preheater of the steam generator system. The two high-temperature high-pressure biomass fluidized bed boilers and the two sets of steam generator systems are connected with a power generation system and also connected with a catalytic synthesis tower.

[0006] Furthermore, the two high-temperature high-pressure biomass fluidized bed boilers generate steam with a parameter of 9.8 MPa / 540 DEG C, which is used to consume biomass energy.

[0007] Further, the low-temperature desalted water is heated by two sets of steam generator systems, and becomes superheated steam of 9.8 MPa / 540 DEG C, which is mixed with steam generated by the high-temperature and high-pressure biomass fluidized bed boiler into a mother pipe to enter the catalytic synthesis tower, so as to provide a stable steam heat source for the start-up stage of the methanol system.

[0008] Further, the steam generated by the two sets of steam generator systems is used as a catalytic temperature heat source for producing methanol, and the other part is used for power generation, so as to ensure stable power supply of the whole system.

[0009] Further, the molten salt electric heater uses abandoned wind and light to heat 290 DEG C low-temperature molten salt into 565 DEG C high-temperature molten salt for storage.

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

[0011] Further, when the molten salt system starts, the pure storage mode is started, the molten salt electric heater is preheated, the low-temperature molten salt pump of the low-temperature molten salt tank is opened, the low-temperature molten salt enters the molten salt electric heater for heating, and then enters the high-temperature molten salt tank for storage, and when the molten salt storage exceeds the capacity of the two sets of steam generator systems in the heat release stage, redundant storage is carried out.

[0012] Further, when one biomass boiler is operated at full load, one set of steam generator system is operated, and the total amount of superheated steam at the outlet section of the system can be met, and in the system, the biomass boiler and the steam generator system are mutually reserved, and can be continuously and stably operated.

[0013] Further, when one biomass boiler is operated at 70% load, two sets of steam generator systems are operated at reduced load, and the total amount of superheated steam at the outlet section of the system can be met, and in the system, one biomass boiler is reserved, and can be continuously and stably operated.

[0014] Further, when two biomass boilers are completely stopped, two sets of steam generator systems are operated at full load, and the total amount of superheated steam at the outlet section of the system can be met, but the steam generator systems need to be operated intermittently.

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

[0016] (1) The biomass boiler is used to consume biomass in the present application, so that zero carbon emission is realized. The methanol purge gas generated in the methanol production process and the excess biomass gas in the biomass gasification methanol production process are treated by the biomass boiler, so that the waste gas disposal cost is reduced, and the use of biomass is reduced.

[0017] (2) The surplus electricity from the new energy source, besides the electricity used for water electrolysis, can be used to heat molten salt with an electric heater and stored in the form of heat. The electricity is effectively utilized. At the same time, during the exothermic phase of the hot molten salt, it can also provide a stable steam heat source for the start-up phase of the methanol system to ensure the activity of the catalyst.

[0018] (3) When the methanol system is running normally, the exothermic reaction of methanol can be used to heat the low-temperature demineralized water. In addition, when there is a lot of electricity, it can also replace part of the biomass boiler load, and the steam generated by the biomass boiler and the molten salt exothermic reaction can be used as backups for each other, ensuring the efficient, safe and stable operation of the methanol production system, and laying the foundation for promoting the large-scale production of methanol. Attached Figure Description

[0019] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0020] Figure 1 This is a schematic diagram of the green, low-carbon biomass coupled molten salt energy storage methanol production system described in this invention; Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0022] See Figure 1 This embodiment describes a green, low-carbon biomass-coupled molten salt energy storage system for methanol production. It includes two high-temperature, high-pressure biomass fluidized bed boilers, a molten salt system, and two steam generator systems. In the methanol production process, the methanol off-gas and excess biomass gas from biomass gasification are combined into a main pipe and fed into the two high-temperature, high-pressure biomass fluidized bed boilers. The molten salt energy storage system includes a low-temperature molten salt tank, a molten salt electric heater, and a high-temperature molten salt tank connected in sequence. Waste electricity from renewable energy sources enters the molten salt electric heater. The steam generator system includes a superheater, an evaporator-start-up protector, 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 aforementioned steam generator system. Both high-temperature, high-pressure biomass fluidized bed boilers and the two steam generator systems are connected to a power generation system and also to a catalytic synthesis tower.

[0023] New energy electricity is partly used for electrolysis of water, and partly as abandoned electricity into molten salt electric heater. Hydrogen produced by electrolysis of water enters catalytic synthesis tower, and oxygen is used for biomass gasification. Carbon monoxide, hydrogen and carbon dioxide produced by the biomass gasification enter the catalytic synthesis tower to synthesize methanol in the catalytic synthesis tower. Biomass, excess biomass gas and formaldehyde exhaust gas enter the high-temperature and high-pressure biomass fluidized bed boiler, and then the superheated steam produced by the high-temperature and high-pressure biomass fluidized bed is used as a catalytic temperature heat source for producing methanol, and the remaining steam enters the power generation system for power generation to ensure stable power supply of the whole system. The high-temperature and high-pressure steam for power generation can improve the unit efficiency.

[0024] The application constructs two high-temperature and high-pressure biomass fluidized bed boilers to produce steam with parameters of 9.8 MPa / 540 DEG C for absorbing biomass energy. Two sets of steam generator systems are arranged to heat low-temperature desalted water to superheated steam with parameters of 9.8 MPa / 540 DEG C, which is merged into a mother pipe together with steam produced by the high-temperature and high-pressure biomass fluidized bed boiler.

[0025] The low-temperature desalted water is water in the deaerator of the high-temperature and high-pressure biomass fluidized bed boiler.

[0026] The low-temperature desalted water is heated by a feedwater heater, a preheater, an evaporator-steam drum and a superheater to become superheated steam with parameters of 9.8 MPa / 540 DEG C. The temperature of the low-temperature desalted water must be higher than the melting point temperature of the molten salt plus 20 DEG C to ensure that the molten salt does not solidify when exchanging heat with the molten salt, thereby affecting the safety of the molten salt.

[0027] In the methanol production process, methanol purge gas (CO, H2, etc.) and excess biomass gas for producing methanol by biomass gasification can be merged into the mother pipe and sent into the high-temperature and high-pressure biomass fluidized bed boiler together.

[0028] The molten salt electric heater uses abandoned wind and light electricity to heat 290 DEG C low-temperature molten salt into 565 DEG C high-temperature molten salt, stores the high-temperature molten salt, and releases heat by using the high-temperature molten salt storage tank.

[0029] In the system, the steam produced by the two sets of steam generator systems and the two high-temperature and high-pressure biomass circulating fluidized bed boilers must be the same.

[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 after heat exchange by the superheater, the evaporator and the preheater enters the low-temperature molten salt storage tank.

[0031] When the molten salt system starts, the pure storage mode is opened, the molten salt electric heater is preheated, and then the low-temperature molten salt in the low-temperature molten salt tank is pumped into the molten salt electric heater for heating, and then into the high-temperature molten salt tank for storage. When the molten salt storage exceeds the capacity of the two sets of steam generator systems in the heat release stage, redundant storage is stored.

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

[0033] The power of the molten salt electric heater needs to be determined to be equal to the steam quantity generated by the heat release system, and the power of the power supply section of the electric heater can ensure the safe and stable operation of the system.

[0034] Each set of molten salt electric heater adopts a safe and stable 10MW electromagnetic molten salt electric heater, and the power fluctuation range of the electromagnetic molten salt electric heater is 2-10MW. According to the on-site power supply situation, different voltage levels of 6 / 10kV are designed, the efficiency is high (>97%), and the appropriate number of electromagnetic molten salt heaters is selected according to the remaining abandoned wind and light electricity.

[0035] The minimum operating load of the steam generator system is set to 30%, in order to realize the mutual backup of the biomass boiler and the steam generator system, therefore, in the whole system, the load range of the biomass boiler needs to be guaranteed to be 70%-100% load, which can guarantee 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 mode of storing while releasing is adopted.

[0037] When one biomass boiler operates at full load, one set of steam generator system can be operated, which can meet the total amount of superheated steam at the outlet section of the system, and in the system, the biomass boiler and the steam generator system are mutually backed up, and can be continuously and stably operated.

[0038] When one biomass boiler is operated at 70% load, two sets of steam generator systems can be operated at reduced load, which can meet the total amount of superheated steam at the outlet section of the system, and in the system, one biomass boiler is in standby, which can be continuously and stably operated.

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

[0040] The above disclosed embodiments of the present application are only used to help explain the present application. The embodiments do not describe all the details of the present application, and the present application is not limited to the specific embodiments described. According to the content of the present specification, many modifications and changes can be made. The present specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present application, so that those skilled in the art can well understand and utilize the present application.

Claims

1. A biomass-coupled molten salt energy storage system for methanol production, characterized in that: The system 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 off-gas and excess biomass gas from biomass gasification are combined into a main pipe and fed into the two high-temperature and high-pressure biomass fluidized bed boilers. The molten salt thermal storage system includes a low-temperature molten salt tank, a molten salt electric heater, and a high-temperature molten salt tank connected in sequence. Waste electricity from renewable energy sources enters the molten salt electric heater. The steam generator system includes a superheater, an evaporator-start-up protection device, 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 aforementioned steam generator system. Both 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 also to the catalytic synthesis tower. When the molten salt system is started, the storage mode is activated, 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 through the low-temperature molten salt tank for heating, and then enters the high-temperature molten salt tank for storage. When the heat storage of molten salt exceeds the capacity of the two steam generator systems in the heat release stage, redundant storage is performed.

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

3. The biomass-coupled molten salt energy storage methanol production system according to claim 2, characterized in that: The low-temperature demineralized water from the deaerator in the high-temperature and high-pressure biomass fluidized bed boiler is heated by the feedwater heater, preheater, evaporator-steam drum, and superheater, and then becomes superheated steam with steam parameters of 9.8MPa / 540℃. This superheated steam is then combined with the steam generated by the high-temperature and high-pressure biomass fluidized bed boiler and flows into the main pipe.

4. The biomass-coupled molten salt energy storage methanol production system according to claim 1, characterized in that: Molten salt electric heaters utilize surplus wind and solar power to heat molten salt at a low temperature of 290℃ to a high temperature of 565℃ for storage.

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

6. The biomass-coupled molten salt energy storage methanol production system according to claim 1, characterized in that: The steam generated by the two steam generator systems is used partly as a catalytic temperature heat source for methanol production and partly for power generation, ensuring a stable power supply for the entire system.

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

8. The biomass-coupled molten salt energy storage methanol production system according to claim 1, characterized in that: When one biomass boiler is reduced to 70% load, two steam generator systems operate at reduced load to meet the total amount of superheated steam at the system outlet. In the system, one biomass boiler is on standby and can operate continuously and stably.

9. The biomass-coupled molten salt energy storage methanol production system according to claim 1, characterized in that: When both biomass boilers are shut down, the two steam generator systems operate at full load to meet the total amount of superheated steam at the system outlet, but the steam generator systems need to operate intermittently.

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