CN101042261B - Method and device for converting solar energy into fuel chemical energy - Google Patents

Abstract

It relates to a method and device of changing solar energy to chemical energy. It accumulates the solar energy and changing it to heat energy ranging from 150deg.C-300deg.C, providing reaction heat for the liquid fuels, allowing the middle and low level solar energy changing and stored into high level chemical energy, with the liquid being carbinol or dimethyl ether synthetic fuel, with the catabolite being hydrogen and monoxide formed gas. It can be used for multi purposes, providing fine synthetic fuel and material for customers.

Description

Method and device for converting solar energy into fuel chemical energy

technical field

The invention relates to the technical field of solar energy and chemical energy, and relates to a new method and device for converting solar energy into fuel chemical energy.

Background technique

Energy is the fundamental guarantee for human development and survival. With the development of economy and population growth, the consumption of energy is increasing day by day. The massive exploitation of fossil energy will make it face exhaustion. At the same time, the discharge of a large number of pollutants will seriously It has seriously polluted the environment, deteriorated the living conditions of human beings, and threatened the sustainable development in the future. Searching for new, renewable and clean energy has aroused widespread concern in the scientific and technological circles around the world. With its unique "infinity" of reserves, universality of existence, and cleanness of development and utilization, solar energy will surely occupy an important place in the future energy structure. However, the discontinuity and low energy flow density of solar energy restrict its own development. Therefore, finding new energy utilization methods, especially the complementary utilization of fossil energy and solar energy, has become the focus of science and technology circles in various countries. At the same time, liquid clean synthetic fuels such as methanol and dimethyl ether have gradually been widely used and become the most promising alternative to conventional energy in the future. mainstream energy. As a "universal intermediate" in the chemical industry, methanol can be synthesized from energy sources such as coal, natural gas, and biomass. It is the only simple chemical that can be synthesized on a large scale by coal gasification and natural gas reforming except synthetic ammonia. Methanol and dimethyl ether, as important clean synthetic fuels, have combustion characteristics similar to oil and are easy to carry and transport. They will be more and more widely used in energy and power, and efficient utilization of methanol and dimethyl ether fuels will be carried out. Research is imperative. Combustion in the general sense is the use of boilers or stoves to directly oxidize and exothermic reaction of methanol and oxygen—that is, direct combustion, which is currently the main way to utilize methanol and dimethyl ether fuels.

When solar energy is used, it usually needs to be converted into other forms of energy. At present, the most widely used conversion method is photothermal conversion. The collection of solar energy generally adopts various concentrators, from low-temperature collectors such as flat plate and vacuum tube to high-temperature collectors such as trough, dish, and tower, to upgrade solar energy to a higher grade for utilization. Generally, the higher the collector temperature, the higher the corresponding cost and the lower the efficiency. To solve the problem of energy discontinuity, heat storage can be used, but how to reduce the volume of the heat storage device is always a difficult problem, and there is inevitable heat loss, so the application is limited. Therefore, the way of comprehensive and complementary use of solar energy and conventional energy has also received greater attention. The current general practice is to complement the functions of solar energy and fuel (including electricity) on their own independent basis, that is, when the solar energy does not reach the required temperature or when there is no solar energy available (cloudy days, nights), it is supplied by fuel. This type of simple Physically complementary systems are widely used in solar heating, cooling, and solar thermal power generation systems. This complementary system is only a simple superposition of solar energy and fossil fuels, or is limited to the cascade utilization of physical energy, and cannot fundamentally improve the utilization efficiency of solar energy. At present, solar thermochemistry and its reaction devices are mainly based on high-temperature heat collection. For example, the system used for natural gas reforming requires a heat collection temperature above 800°C, which greatly increases the conversion cost of solar energy to chemical energy.

Contents of the invention

The purpose of the present invention is to provide a method for converting solar energy into fuel chemical energy. In this method, solar energy directly provides heat for endothermic chemical reactions without heat medium. The system flow is simple, and the cost of using heat medium can be reduced. At the same time, heat loss caused by heat medium storage and transfer can be avoided.

Another object of the present invention is to provide an energy conversion device for realizing the above method, which is a parabolic trough solar absorber developed for the first time that is different from the high-temperature heat collection thermochemical process and a substitute liquid fuel decomposition catalyst The integrated integrated device of reaction equipment, with this as the core, together with auxiliary systems such as feed and product separation, constitutes a solar thermochemical conversion device.

Another object of the present invention is to provide an energy conversion device that can realize the complementarity of solar energy and conventional energy, and use solar energy to convert liquid fuel into high calorific value clean gas synthetic fuel, which can realize the conversion of fuel chemical energy including methanol or dimethyl ether. Cascade utilization and grade upgrading and chemical storage of low-grade solar thermal energy to high-grade fuel chemical energy.

In order to achieve the above object, the technical solution of the present invention is to provide a method for converting solar energy into fuel chemical energy, using a solar heat collection/reaction integrated system to directly collect and irradiate solar energy on the absorber/reactor, and convert solar energy Convert to heat energy at 150°C-300°C, supply heat for the decomposition reaction of liquid fuel in the reactor, convert and store medium and low temperature solar energy into high-grade decomposition product chemical energy, and release high-grade heat energy through combustion of the decomposition product;

Among them, the liquid fuel is methanol or dimethyl ether synthetic liquid fuel; the decomposition product is synthesis gas mainly composed of hydrogen and carbon monoxide.

In the method, the decomposition products produced by the decomposition reaction of the liquid fuel first enter the condenser to cool and lower the temperature to condense the unreacted substances, and then the gas-liquid mixture enters the separator to realize gas-liquid separation, and the synthesis gas of hydrogen and carbon monoxide The output is for use or storage, and the unreacted materials are returned to the mixer, and then pumped to the cooling evaporator for recycling through raw materials.

A device used in the method includes a raw material tank, a parabolic trough solar concentration device, a cooling evaporator, a condensation cooler, a separator, a mixer, a raw material pump and pipelines, wherein the parabolic trough solar concentration The device is a linear concentrating device, the cooling evaporator and the condensing cooler are partitioned heat exchange equipment, and the components are connected by sealed pipes according to the industry's routine; it also includes an absorption/reactor, the absorption/reactor is a long tubular Equipment, matching the length of the parabolic trough solar concentrator, placed at the focal line of the parabolic trough solar concentrator, with enhanced selective absorption coating for high solar absorption, low emissivity and low reflectivity The surface and jacket are high-transmittance glass sleeves that reduce convection and heat conduction losses; the long tubular equipment is filled with the catalyst required for the reaction; the inlet of the absorption/reactor is sealed by pipes and connected to the cooling evaporator, and the outlet is sealed by pipes and connected to condensing cooling device.

Said device, said cooling evaporator, its external heat source is a heat source of 80-120°C. The cooling evaporator uses a lower temperature heat source to preheat the raw material, which can save energy, but it can be replaced by a solar collector for the purpose of simplifying the equipment.

In the device, the heat source is a parabolic trough solar concentrator, a vacuum tube or flat plate solar collector, an external boiler, or the waste heat of the reaction product of the device.

In the device, the waste heat of the reaction product of the device is to absorb/utilize the heat recovery of the superheated mixed gas of the reaction product at the outlet of the reactor, and pass the superheated mixed gas of the reaction product into the heating pipe of the cooling evaporator as a raw material for preheating Part of the heat source, the insufficient part is supplemented by an external heat source at 80-120°C, and the mixed reaction product that has cooled down after exothermicity is passed into a condensing cooler for further condensation treatment.

In the device, the catalyst is a solid metal oxide catalyst.

In the device, the long tubular equipment is a copper tube; the coating surface is an aluminum-containing cermet film; the glass sleeve is a high borosilicate glass tube.

The energy conversion method of the present invention has the following three characteristics:

① Integration of heat collection temperature and reaction temperature of the solar concentrating device: the temperature level that the solar concentrating device can provide is consistent with the temperature required for the decomposition reaction, realizing temperature matching, grade coordination, and reasonable utilization of medium and low temperature solar energy;

②Integration of solar absorber and reactor equipment: The integrated equipment placed on the focal spot of the solar concentrating device is both a solar absorber and a reactor, and the concentrated sunlight with high energy flux density directly irradiates the absorber/reactor , to directly provide heat for endothermic chemical reactions without heat medium;

③Integration of structural features of the reaction absorber: The pipe diameter width of the absorber/reactor and the focal line width of the light concentrating device are coordinated and matched, which not only helps to reduce heat loss and improve heat collection efficiency, but also facilitates the decomposition reaction and realizes heat transfer and reaction coupling.

The device of the present invention has the following three advantages:

1) The design of the device uses an integrated method, which realizes the coordination and matching of the solar heat collection temperature and the catalytic decomposition temperature of liquid fuels such as methanol and dimethyl ether, which reduces the cost of the solar heat collector and reduces the availability of the heat utilization process of the entire system. energy loss, which is better than the thermochemical method using high-temperature solar collectors; the absorber is integrated with the reactor; the solar absorber and reactor in the system are integrated, which reduces the equipment and avoids the resulting Heat transfer and transport heat loss; the integration of absorption/reactor structural features not only helps to reduce heat loss and improve heat collection efficiency, but also facilitates the decomposition reaction, realizes the coupling of heat transfer and reaction, and obtains a good solar energy conversion effect .

2) Energy conversion and utilization: After decomposition, the fuel chemical energy of methanol and dimethyl ether is converted into fuel chemical energy of _H2 and CO, and solar thermal energy is also converted into chemical energy of _H2 and CO. The effect of the system on the level of the first law of thermodynamics is to increase the calorific value of methanol and dimethyl ether fuels, and the increased part is equal to the solar thermal energy absorbed by the decomposition reaction; the effect on the level of the second law of thermodynamics is reflected in the grade of solar thermal energy Ascension, through fuel decomposition reactions such as methanol and dimethyl ether, the low-grade solar thermal energy is upgraded to high-grade _H2 and CO chemical energy, which increases the working ability of solar thermal energy. The overall effect is to reduce the loss of fuel chemical energy to thermal energy conversion process in the traditional combustion process, and improve energy utilization efficiency.

3) It has greater advantages for the following users: users who need gas fuel but do not have gas access conditions (such as around cities, areas that cannot be covered by natural gas pipeline networks, areas where terrain conditions such as mountains and islands are not conducive to gas supply); solar radiation Good lighting resources (most areas of my country, especially the western region); methanol and dimethyl ether fuel consumption has a certain scale (distributed energy stations, methanol, dimethyl ether heating or power, power generation systems), methanol, dimethyl ether Users who use methyl ether as raw material to prepare synthesis gas.

The invention can be used for various purposes, such as heat supply, refrigeration, fuel-solar combined power generation, combined cooling, heating and power supply in which solar energy and fuel are complementary, and gas production, etc., and uses solar energy to provide users with high-quality syngas fuel or raw materials.

Description of drawings

Fig. 1 is the working principle diagram of method or device of the present invention;

Fig. 2 is the schematic diagram of energy grade conversion of the present invention;

Fig. 3 is a schematic diagram of the device structure and flow chart of the present invention.

Detailed ways

A method for converting solar energy into fuel chemical energy provided by the present invention, as shown in Figure 1, wherein the sunlight with high energy flux density collected by the heat collector is irradiated on the absorber/reactor, directly for the decomposition reaction of the fuel Provide heat to obtain the decomposition product synthesis gas; thus the solar thermal energy is converted and stored in the chemical energy of the decomposition product, the grade of low-temperature solar energy is improved, and converted into high-grade synthesis gas chemical energy, which is further used as fuel.

In the above process, the energy grade conversion is shown in Figure 2: in the figure, the abscissa is the process enthalpy change, and the ordinate is the energy grade A, which is defined as the ratio of the process available energy change to the enthalpy change. Therefore, it can be seen that the area surrounded by abcda in the figure is the direct combustion-loss of methanol, the area surrounded by efgde in the figure is the combustion-loss of decomposition products, and the area surrounded by cgnmc in the figure represents the income generated by the improvement of solar thermal energy grade in the new mechanism. The fuel decomposition process can be understood in the figure as the calorific value |ab|, the grade is about A ₁ =1.02; the heat absorbed by methanol (solar heat energy) is |mn|, the grade is about A ₂ =0.44; the calorific value of the decomposition product fuel is |ef |, the grade is about A ₃ =0.95.

Described fuel is methanol or dimethyl ether liquid;

The decomposition products are synthesis gas with _H2 and CO as main components.

The present invention provides an energy conversion device for realizing the above method, please refer to FIG. 1 for the working principle diagram of the device. The device of the present invention uses medium and low temperature solar energy at 150°C to 300°C to provide heat energy for the endothermic decomposition reaction of raw material methanol or dimethyl ether, and produces synthesis gas whose main components are hydrogen (H ₂ ) and carbon monoxide (CO). The chemical energy converted into syngas increases the calorific value of the fuel, improves the grade of solar energy, and increases the working ability of solar energy.

As shown in Figure 3, the device of the present invention mainly includes:

Parabolic trough solar concentrating device 5: select the parabolic trough solar concentrating device 5 that adopts the line focusing method, the concentration ratio is about 60-150, and the heat collection temperature can reach 200°C-400°C. The reaction temperature range is 150°C The decomposition reaction of liquid fuel between ℃ and 300℃ provides heat to realize the integration of heat collection temperature and reaction temperature of the solar concentrating device;

Absorption/reactor 6: It is a tubular device placed at the focal line of the parabolic trough solar concentration device 5, which is both a solar absorber and a thermochemical reactor. As an absorber, it has an enhanced selective absorption coating surface with high absorptivity, low emissivity and low reflectivity for sunlight, and a glass sleeve with high transmittance to reduce convection and heat conduction losses; as The reactor is filled with the catalyst required for the reaction; the absorption/reactor 6 is connected to the cooling evaporator 4 and the condensation cooler 7 .

The cooling evaporator 4 is a partitioned heat exchange device, which is respectively connected to the absorption/reactor 6 and the raw material pump 3 to receive the raw material from the mixer 2, where the raw material is preheated, evaporated, and superheated to become a gaseous reactant; cooling The heat source of the evaporator 4 can be any heat source higher than 80°C, such as the above-mentioned various concentrating solar devices or vacuum tube solar collectors, and other external heat sources;

The condensing cooler 7 is a partition-type heat exchange device, connected to the absorption/reactor 6 and the separator 8, and condenses the decomposition products from the absorption/reactor 6.

Separator 8 is a gas-liquid separation device. The mixture cooled down in the condensing cooler 7 is subjected to gas-liquid separation, and the condensing cooler 7 and the mixer 2 are connected respectively. The reaction product of the gas phase is used as a product, and the liquid phase components are returned to mixer 2.

The mixer 2 receives and mixes the fresh raw material from the raw material tank 1 and the unreacted matter separated by the separator 8, and the raw material pump 3 connected to it provides raw material for the absorption/reactor 6.

The flow process of the device of the present invention is: after the raw material in the raw material tank 1 is sent to the cooling evaporator 4 through the mixer 2 and the raw material pump 3 for preheating, evaporation, and superheating, the raw material gas formed enters the absorption/reactor 6, and after the absorption/reactor 6 Reactor 6 absorbs solar heat energy at 150°C to 300°C, and at the same time, undergoes endothermic decomposition reaction under the action of a catalyst. After the reaction produces hydrogen (H ₂ ) and carbon monoxide (CO) synthesis gas, it first enters the cooling evaporator 4 for cooling Lower the temperature to condense the unreacted substances, then the gas-liquid mixture enters the separator 8 to realize gas-liquid separation, the synthesis gas of hydrogen (H ₂ ) and carbon monoxide (CO) is output for use or storage, the unreacted substances are returned to the mixer 2, and then passed through The raw material pump 3 is sent to the cooling evaporator 4 for recycling.

In the device of the present invention, the concentrating device 5 is various parabolic trough solar linear concentrating devices.

In the device of the present invention, the condensing cooler 7 is connected with circulating cooling water.

In the device of the present invention, a chemical metering pump is connected downstream of the raw material tank 1, and the raw material tank 1 communicates with the mixer 2 through the chemical metering pump (not shown in the figure).

The device of the present invention also includes the recovery utilization of the superheated mixed gas of the reaction product at the outlet of the absorption/reactor 6, that is, the superheated mixed gas of the product is passed into the cooling evaporator 4 as a part of the heat source for the preheating of the raw material, and the insufficient part is made of any temperature higher than 80 ° C. The external heat source is supplemented, and the mixed product that cools down after exothermicity is passed into the condensing cooler 7 for further condensation.

Please combine with Fig. 3, the solar energy decomposition substitute liquid fuel device is made up of solar concentrating device 5, integrated absorption/reactor 6 and other auxiliary equipment.

The liquid methanol or dimethyl ether raw material in the raw material tank 1 is fed into the mixer 2 through the pipeline 9, and then through the pipeline 10, and is sent to the cooling evaporator 4 through the pipeline 11 by the raw material pump 3 at a flow rate of 500-10000ml/h. After preheating, evaporation, and overheating, the superheated raw material gas enters the absorption/reactor 6 through the pipeline 12; A decomposition reaction occurs in the absorption/reactor 6 to generate a mixed product containing H ₂ , CO, unreacted raw materials and a small amount of by-products. The mixed product first enters the cooling evaporator 4 through the pipeline 13 to preheat the raw material, and the supplementary heat source enters through the pipeline 18. Pipeline 19 exits, at the same time the temperature of the mixed product itself drops, partially condenses, and then enters the condensing cooler 7 through the pipeline 14, and enters the separator 8 through the pipeline 15 after being cooled to below 25°C, and the main components _H2 and CO are gases with good properties The synthetic fuel is discharged from the pipeline 17 and sent to the downstream for direct utilization or storage. The unreacted raw material and a small amount of liquid by-products come out from the separator 8, and return to the mixer 2 through the pipeline 16, and continue to use after being mixed with the fresh raw material from the raw material tank 1 entering the 2 through the pipeline 9. The cooling medium of the condensing cooler 7 enters through the pipeline 20 and exits from the pipeline 21 to cool the reaction product, and the cooling medium can be recycled.

Various equipments in the device of the present invention are known technologies, such as:

The solar concentrating device 5 adopted in the present invention can be various parabolic trough concentrating devices.

The cooling evaporator 4 or condensing cooler 7 of the present invention can be various partition wall heat exchangers.

The catalyst used in the present invention may be a known catalyst used in the decomposition reaction of methanol or dimethyl ether, such as a solid metal oxide catalyst.

Since the focus of the present invention is to convert solar energy into chemical energy of fuel products through solar thermochemical processes, the above-mentioned specific equipment belonging to the known technology will not be described in detail.

The following examples can illustrate the effect of the present invention:

A parabolic trough solar concentrating device 5 with a concentration ratio of 70 and a maximum output heat power of 4kW is used, and a long copper tube with an outer diameter of 35 mm is used as the absorber/reactor 6, and the outer surface of the copper tube is coated with an absorptivity of 0.9 , an aluminum-containing cermet film with an emissivity of 0.085, and a high borosilicate glass tube with a jacket diameter of 56 mm; the raw material is liquid industrial methanol with a concentration of 99.9% at normal temperature and pressure, and the catalyst is Cu/ZnO/Al ₂ O ₃ series solid metal oxide catalyst.

The liquid phase product separated from the lower end of the separator 8 is mainly unreacted raw materials and a small amount of liquid by-products, and the gas phase product separated from the upper end of the separator 8 is more than 90% H2 _and CO, plus a small amount of combustible raw materials and Synthesis gas composed of carbon dioxide (CO ₂ ).

The pipeline flow parameters of this embodiment are shown in Table 1.

In this embodiment, when the solar radiation is 700 W/m ² and the liquid methanol feed rate is 5 liters/hour, the methanol conversion rate reaches 80%, and the solar heat utilization efficiency reaches 77%.

From the perspective of energy grade, this embodiment has more obvious advantages. The concept of energy grade is equal to the Carnot cycle efficiency for thermal energy. Under the above reaction conditions, the solar thermal energy at 260°C is transformed into the chemical energy of the decomposition product mixture gas through the methanol decomposition reaction, and the energy grade is increased from 0.443 to 0.923, which greatly increases its working ability, and at the same time enables the energy utilization system to be used in fuel combustion. Compared with the direct combustion process, the loss is reduced by 30.8%.

Table 1 pipeline process parameters of the embodiment of the present invention

Pipe number Medium in the pipeline Temperature (atmospheric pressure) 9 fresh ingredients, liquid 16°C 10 mixed ingredients, liquid 16°C 11 mixed ingredients, liquid 18°C 12 superheated raw material, gas 100℃ 13 reaction product mixture, gas 200～300℃ 14 Reaction product mixture, gas-liquid mixture 50℃ 15 Reaction product mixture, gas-liquid mixture 20℃ 16 Reaction products and unreacted substances, liquid 20℃ 17 Syngas, gas 20℃ 18 external heat source 120℃ 19 external heat source 80℃ 20 Circulating cooling water 17℃ twenty one Circulating cooling water 20℃

Claims (8)

1. A method for converting solar energy into fuel chemical energy, using a solar heat collection/reaction integrated system, characterized in that: The solar heat collection/reaction integrated system directly collects and irradiates solar energy on the absorber/reactor, converts solar energy into heat energy at 150°C-300°C, supplies heat for the decomposition reaction of liquid fuel in the reactor, and converts medium and low temperature solar energy , Stored as high-grade decomposition product chemical energy, and then release high-grade heat energy by burning the decomposition product; Among them, the liquid fuel is methanol or dimethyl ether synthetic liquid fuel; the decomposition product is synthesis gas mainly composed of hydrogen and carbon monoxide. 2. The method according to claim 1, characterized in that: the decomposition product produced by the decomposition reaction of the liquid fuel first enters the condenser to cool and lower the temperature to condense the unreacted matter, and then the gas-liquid mixture enters the separator to realize gas Liquid separation, hydrogen and carbon monoxide synthesis gas output for use or storage, unreacted materials are returned to the mixer, and then pumped to the cooling evaporator for recycling through raw materials. 3. A device used in a method as claimed in claim 1, comprising a raw material tank, a parabolic trough solar concentration device, a cooling evaporator, a condensing cooler, a separator, a mixer, a raw material pump and a pipeline, wherein, The parabolic trough solar concentrating device is a linear concentrating device, the cooling evaporator and the condensing cooler are partitioned heat exchange equipment, and the pipes of each component are sealed and connected; it is characterized in that it also includes an absorption/reactor, an absorption/reactor It is a long tubular device, matching the length of the parabolic trough solar concentrator, placed at the focal line of the parabolic trough solar concentrator, with a coated surface, and a glass sleeve; the long tubular device is filled with the required reaction The catalyst; the inlet of the absorption/reactor is connected to the cooling evaporator by a pipe seal, and the outlet is connected to the condensing cooler by a pipe seal. 4. The device according to claim 3, characterized in that the external heat source of the cooling evaporator is a heat source of 80-120°C. 5. The device according to claim 4, characterized in that: the heat source is a parabolic trough solar concentrator, a vacuum tube or flat panel solar collector, an external boiler, or the waste heat of the reaction product of the device. 6. The device as claimed in claim 5, characterized in that: the waste heat of the reaction product of the device is to absorb/recover the superheated gas mixture of the reaction product at the outlet of the reactor, and pass the superheated gas mixture of the reaction product into the cooling evaporation The heating pipe of the device is used as part of the heat source for raw material preheating, and the insufficient part is supplemented by an external heat source at 80-120 ° C. After exothermic cooling, the mixed reaction product is passed into the condensing cooler for further condensation treatment. 7. The device according to claim 3, wherein the catalyst is a solid metal oxide catalyst. 8. The device according to claim 3, characterized in that: the long tubular device is a copper tube; the coating surface is an aluminum-containing cermet film; and the glass sleeve is a high borosilicate glass tube.

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