RU2335118C2 - Method of using solar energy - Google Patents

Abstract

FIELD: agriculture.

SUBSTANCE: invention relates to forest management. The method involves burning woody materials in the access of oxygen producing heat and carbon dioxide containing gas mixture. Then carbon dioxide is extracted out of the mixture and dry ice is obtained. The dry ice is delivered to forest area, regasified, distributed over the area by mixing with air till excessive average daily concentration of carbon dioxide reaches 0.005% to 0.2% by volume. Further carbon dioxide is absorbed in the photosynthesis process by the trees which are burnt later.

EFFECT: removing carbon dioxide from the atmosphere and providing for fast forest growth.

1 tbl, 3 ex

Description

The present invention relates to the fields of energy and ecology and, in particular, to methods of forestry, as well as to methods of chemical and biological treatment of exhaust gases from pollution by industrial carbon dioxide emissions.

Using wood as a renewable fuel is known as the most affordable way to use solar energy. At the same time, when burning all types of fossil fuels, carbon dioxide is released, which is one of the main air pollutants, the fight against which is announced by the Kyoto Protocol. At the same time, the forest is a natural and large-scale absorber of carbon dioxide. By developing this natural cycle of the carbon cycle, energy and environmental crises can be avoided.

The Known Method of growing woody plants according to the patent of the Russian Federation No. 2017402 (class. IPC A01G 23/00), according to which the forest is growing due to regular maintenance.

There is also known a Method of increasing forest productivity according to patent No. 2054242, according to which trees of main use are selected and grown in the forest.

There is also known a Method of biological protection of the environment from ecotoxicants according to patent No. 2092031, in which the forest is used to absorb toxic gases.

There is also known a Method of creating protective plantings around industrial enterprises according to patent No. 2197079, according to which trees are planted next to them to absorb harmful emissions from enterprises with the creation of terraces and irrigation systems.

Known System for air purification from carbon dioxide according to the patent of the Russian Federation No. 2097115 (class IPC B01D 53/62), according to which carbon dioxide (UG) is absorbed in the adsorbent adsorbent layer, and then regenerated.

There is also known a device for extracting carbon dioxide from gas mixtures according to patent No. 2207185, in which carbon dioxide is extracted from the mixtures by cooling and washing with absorption of carbon dioxide by an agent circulating in a closed cycle through the absorber.

There is also known a Method for the disposal of flue gases according to patent No. 2185323, in which flue gases are cooled, and the gas is extracted from the mixture by wet filtration.

Methods are also known for condensing HC into liquid and dry ice.

The Known Method for producing carbon dioxide ice by ed. St. USSR No. 1703617, in which the freezing of a part of liquid carbon dioxide is carried out by supercooling it during sublimation and removal of the gaseous phase.

There is also known a method of producing dry ice by ed. St. USSR No. 1112202 (class IPC СВВ 31/22), according to which UG are compressed, cooled, liquefied and throttled to the pressure of formation of dry ice.

The latter method is adopted as a prototype of the proposed method. The described method does not solve the problem of removing hydrocarbons with obtaining solar energy.

According to the proposed method, wood materials, like any hydrocarbon fuel, are burned with oxygen to produce heat and a mixture of gases containing carbon dioxide (UH), the latter is isolated from the mixture and condensed into liquid or dry ice.

In contrast to the known method, the condensate obtained is delivered to the forest area, regasified, distributed over the area of the zone and mixed with air until an excess average daily concentration of HC from 0.05% to 0.02% by volume is obtained for its absorption as a result of photosynthesis by trees, which subsequently burned.

Useful effects of the proposed method are the use of wood materials as a renewable carrier of solar energy, the removal of emitted hydrocarbons from the atmosphere and the accelerated growth of forests to restore and enrich the natural habitat. As a result of the proposed cycle of using wood, the amount of carbon dioxide in the atmosphere will decrease significantly, since when burning wood, most of the energy is released due to the combustion of hydrogen during a circular carbon revolution.

Moreover, due to the prevalence of forests on Earth, the delivery of carbon dioxide from the place of its allocation to the place of removal in most countries is not difficult. In the future, forests can be grown near objects generating UG. In this case, the delivery of hydrocarbons to the forest can be carried out not only by mobile transport, but also by a pipeline in the form of a mixture of dusty dry ice with air. The gas condensate is delivered to the forest, the dimensions of which are calculated for a specific industrial facility, equating its gas emission capacity for gas absorption in the entire zone of the forest. Thus, the zone of removal of hydrocarbons occupies a certain territory. In areas where in winter the forests freeze and stop the absorption of hydrocarbons, open dry ice stores with simple thermal insulation can be set up at this time.

The site of regasification of HC can be in the center or anywhere inside or outside the removal zone. Gas regasification can be carried out in a heat exchanger with any heat carrier. In this case, the regasification energy allows you to raise the gas pressure and use it to distribute and mix the gas with air.

To distribute gas over the area of the removal zone, a system of pipes, for example, diverging from the center of the zone, can be used. To mix UG with air, the pipes can have metering holes located along the length of the pipes.

The difference of the proposed method is also the intensification of the process of absorption of hydrocarbons by plants due to the excess of the normal concentration of hydrocarbons in the air. Instead of the normal content of UH in air of 0.03%, it is proposed to mix UH in an excessive ratio with air from 0.05% to 0.02% by volume.

The results of many experiments on the study of gas exchange over a long period of time are known, during which a close relationship was observed between the absorption of hydrocarbons and the increase in dry biomass.

The results of studies of the daily course of growth, photosynthesis in winter wheat are also presented (Shevelukha, Kovalev, 1973).

The intensity of photosynthesis of various plant species largely depends on a large number of external factors, among which the most important are: light (intensity and spectral composition), temperature, concentration of CO ₂ and O ₂ water regime, mineral nutrition, as well as internal characteristics - age , chlorophyll content, etc. Quantitative and qualitative characteristics of the photosynthetic productivity of C ₃ and C ₄ plants are given in the table.

Indicator Sizes C ₃ plants With ₄ plants Source Primary Fixation Products CO ₂ - FGK Apple to-that Also Optimal temperature for photosynthesis ° C 20-25 30-40 Raghawendra, 1978; Bykov, 1980; Berry et al. 1987 Network photosynthesis saturation Klk 20-40 60-90 Raghawendra, 1978; Rubin 1979; Bykov, 1980 СО ₂ - compensation item % > 0.005 <0.005 Rubin et al. 1977; Raghawendra, 1978 Optimal concentration of CO ₂ in the air % 0.007-0.10 0.03-0.04 Also Inhibition of O ₂ photosynthesis intensity Significant Not measured Sodium 1984; Edwards et al. 1986 The maximum intensity of photosynthesis Mg (CO ₂ ) dm ^-2 · h ^-1 25-40 50-90 Salep, 1977; Sodium, 1984 Transpiration coefficient g N ₂ About g dry. Mass days ^-1 400-500 200-400 Bykov, 1980 Maximum daily biomass increments C / ha day 1,5-3 8-9 Ustenko, 1978

Calculation of the energy efficiency of photosynthesis shows that the absorption of 1 CO ₂ molecule during photosynthesis requires about 8-10 quanta of PAR, or an average of 500 kcal of energy, and the absorption of 1 gram molecule of CO ₂ uses 112 kcal, which is 22.4% absorbed energy. Plants spend 20-30% of the stored energy on breathing. Thus, the efficiency of absorbed PAR for field plants is 16–8% (Nichiporovich, 1978).

The content of CO ₂ in the air is one of the most important factors determining the intensity of photosynthesis. Its concentration under natural conditions is very small (0.03%, or about 300 mg / l), and each variation in the content of CO _{2 is} reflected in the amount of photosynthesis. As can be seen from the table, in C ₄ plants carbonation occurs at lower concentrations (0.04%) than in C ₃ (0.1%).

Currently, in vivo, the CO ₂ content is often the main factor limiting the intensity of photosynthesis. At the University of Antwerp's Faculty of Biology (Nijes et al., 1988), the effect of atmospheric CO ₂ concentration on gas exchange, the growth and productivity of pasture ryegrass in closed greenhouses at CO ₂ 367 and 620 cm ³ / m ^{3 was} studied. Crops grown at a high concentration of CO ₂ accumulated an average of 43% more dry matter compared to a lower carbon dioxide content (367 cm ³ / m ³ ).

In the laboratory of the radiographic service of France, the reaction of wheat to an increase in the CO ₂ content at different seeding densities was studied (Cloux et al., 1987). Wheat plants were grown under controlled conditions at a concentration of CO ₂ 330 and 660 cm ³ / m ³ . The ratio of the dry weight of plants at a high concentration of CO ₂ to the dry weight in the control was 15.50 days later, 1.50. The relative increase in phytomass increased during the first 13 days.

Florida Agricultural Research Specialists (Allen el et., 1987) studied the effects of carbon dioxide concentrations on photosynthesis, biomass growth, and soybean yield using field cameras. It was noted that with an increase in the CO ₂ content in the air from 315 to 630 μl / L, the increase in photosynthesis was 53%, plant biomass - 43%, and grain yield - 32%.

In VIUA, the effect of various concentrations of CO ₂ in the air (350 and 700 μl / l) on the intensity of photosynthesis, growth, development and productivity of various varieties of wheat and barley under temperature conditions (day / night) was studied in the phytotron - 20/14, 23/17 , 28/23 ° С and radiant flux power of 130 W / m ² (Pukhalskaya, 1997). The possibility of increasing grain productivity with a doubling of carbon dioxide content was shown — wheat, on average, by experiments by 43% and barley by 54%.

There is a relationship between factors. As in the case of other life processes, the general principle of limitation is manifested - the speed of the process is determined by the factor that is at a minimum. Thus, when the CO ₂ content in the air is 0.02%, the light saturation of photosynthesis occurs even at an illumination of 8 klx, and with an increase in the concentration of carbon dioxide, the point of light saturation also increases (Obraztsov, 1981).

It was found that an increase in the concentration of CO ₂ leads to a proportional increase in the intensity of photosynthesis and, as a consequence, an increase in respiration.

The influence of UG on forest growth was studied by American scientists at the Carnegie Institution of Washington. They found that an increase in nitrogen condensation in the soil in combination with more humid air, an increase in temperature and concentration of HC caused an increase in plant growth by 44%.

(Source: The Straits Times)

Scientists from Duke University under the direction of William Schlesinger (William Schlesinger) monitored the growth of adult trees in the Duke Forest. It turned out that the trees in the “atmosphere of 2050,” that is, at double the concentration of hydrocarbons, bound 27% more carbon than the trees in the control plots.

(Source: Based on New Scientist.)

Over the past six years, Norby and his colleagues at the Oak Ridge National Laboratory have investigated the effects of rising levels of carbon dioxide on a forest strip of trees a few miles away. The experiment consisted of continuous artificial injection of tons of carbon dioxide into the forest belt, which increased the concentration of carbon dioxide in the environment of trees by about 370 times compared to the usual level. The effects of this exposure have been studied for several years. The results showed that young trees and other green plants respond favorably to increasing atmospheric carbon dioxide concentrations. At the same time, it was not taken into account that, with the growth of CO ₂ , the growth of tree roots also significantly increased.

However, the long life of trees and their large sizes are the reason that forests are difficult to saturated with carbon dioxide.

Forest plants, unlike field plants, have significantly different growth conditions. The luminous flux incident on the fields is not used efficiently enough, since a significant part of it is absorbed by the earth, reflected from it and from plants, and the plants themselves have a limited foliage surface. At the same time, an increase in daily air temperature and a decrease in humidity negatively affect photosynthesis. In the forest, the use of luminous flux is more complete. The multi-tiered arrangement of foliage on trees provides a reduction in energy loss, good dispersion of the light flux, a significantly larger surface of the foliage, stable maintenance of normal temperature and high humidity in the forest. However, with active photosynthesis in the forest volume, the concentration of HC in the air decreases, which significantly slows down the process of gas absorption. This is confirmed by the above experiments. The growth of trees with an increase in the concentration of HC even without taking into account the growth of root systems amounts to volumes that far exceed the natural growth of the forest. Thus, one should expect significantly higher levels of PAR use in the forest, up to 60% and more. In addition, observing in natural conditions a significant difference in the growth rate of some tree species, it can be expected that individual species, such as poplar and aspen, are able to absorb UG more intensively.

Thus, it can be expected that the productivity of forest species with enhanced carbon dioxide supply will increase with increasing concentration of hydrocarbons. Under these conditions, to absorb the GHG emissions of a large TPP at about 200 t / h, a limited gas removal zone with an area of several square kilometers will be required. This is quite acceptable to achieve the goal - the removal of hydrocarbons in the equipped area of the forest.

Example 1. A conventional coal-burning thermal power plant can be converted to the combustion of pulverized wood having calorific value of brown coal. Flue gases from a wood-burning thermal power plant with a flow rate of 1 million m ³ / h after cleaning from fly ash are cooled with water in a wet scrubber, and then with a refrigerant to the freezing point of water. After separation of the ice, the gas mixture is refrigerated in the heat exchanger with a refrigerant to the temperature of the transformation of HC into dry ice. Gas consumption is 216 t / h. A solid, dusty gas is separated from the gas mixture and fed by pneumatic transport to a thermally insulated container, and the cooled gas mixture is used in the regenerative cycle as a derivative of the refrigerant, heated by the oncoming gas stream and released into the atmosphere. The main refrigerant used is liquid air or nitrogen. Solid HC with a flow rate of about 216 t / h is delivered in containers to the equipped area of the nearest forest. The forest area is equipped with a regasifier and a network of pipes that distribute HC across the entire area of the zone. UG regasifier can be located in the center of the zone. In the regasifier UG is heated with a coolant to normal temperature and fed into the pipe network under a pressure of 3-5 kPa. As a heat carrier, products of fuel combustion or air are used. The air cooled in the regasifier is used in the refrigeration cycle for liquefying air. Pipes are laid from the center of the zone by rays and reduce their diameter in proportion to the distance from the center. In the pipes, metering holes are made along their length, through which the UG exits and mixes with air. Upon the expiration of HC in the atmosphere, air is ejected into the stream and the concentration of carbon dioxide decreases to 3-5%. Further mixing of hydrocarbons with air occurs due to convective, diffusion, turbulent and wind transport for the time before the start of daytime photosynthesis of hydrocarbons. By this time, the calculated concentration of HC in air exceeds the nominal concentration by 5.5 times and is about 0.3%. During the day, as the absorption of hydrocarbons, its concentration in air decreases to a nominal 0.05%. In winter, pulverized hydrocarbon is continuously fed to another part of the forest, where the whole hydrocarbon is accumulated in the tanks of a thermally insulated cold store. During the winter, they accumulate up to 1.1 million tons of hydrocarbon, which occupies a volume of up to 700 thousand m ³ . Such a cold store today has feasible dimensions of 130 × 130 × 50 m and the size of existing facilities - gas vessels with a capacity of more than 200 thousand m ³ for transportation of liquefied natural gas.

The average PAR value is taken to be 1 kW / m ² , or 1000 MW / km ² .

UG is supplied and distributed throughout the zone continuously throughout the day. Assuming an equal division of the day between night and day, at 12 o’clock, we determine the average daily excess concentration of HC as a 6.5-fold hourly consumption of HC supplied to the zone and equal to 60 kg / s in the case of arable land, or at a density of 1.73 kg / m ³ - 125 thousand m ³ / hour. The air volume in the zone at a tree height of 15 m is 15 million m ³ / km ² . Taking the photosynthesis efficiency of 17% and attributing it to the excess mass of hydrocarbons, we determine the energy of absorption of hydrocarbons as 280.8 kW / g and the absorption capacity of the forest, equal to 12.8 t / km ² · hour. The required area of the zone will be 16.8 km ² , and the average daily concentration of hydrocarbons in the zone will be 0.05%. Thus, a decrease in the concentration of HC in the absorption zone below 0.05% is unprofitable, since it increases the size of the zone and the cost of its equipment with pipes.

Example 2. The maximum conversion efficiency of light energy into biomass can be no more than 70%. Assuming for the conditions of Example 1 the efficiency of assimilation of hydrocarbons equal to 68%, we determine the energy of absorption of hydrocarbons as 70.2 kW / g and the absorption capacity of the forest as 51.2 t / km ² . In this case, the size of the absorption zone of hydrocarbons will be 4.2 km ² , and the average daily concentration of hydrocarbons in the zone will be 0.2%. A larger increase in the content of HC in the air is impractical, since the absorption of carbon dioxide will be limited due to a lack of light energy.

Example 3. The most likely for the forest average value in the indicated range of the absorption efficiency of hydrocarbons, that is 34%. Under the conditions of example 1, we determine the absorption energy of UG as 140.4 kW / g and the absorption capacity of the forest as 25.6 t / km ² . In this case, the size of the absorption zone of the gas will be 8.4 km ² , and the average daily concentration of gas in the zone will be 0.1%.

The above calculations show that, in practice, for the maximum emission of an industrial facility, the dimensions of the gas removal zones in all examples have a real value suitable for the necessary arrangement.

The proposed technical solution has a wide field of application, since the main sources of industrial GHG emissions are fuel-burning industrial enterprises: thermal power plants, metallurgical, chemical, cement and other plants that operate, as a rule, in continuous mode and use non-renewable energy sources. On the other hand, the absorption capacity of various trees has not yet been adequately studied, which allows us to rely on the presence and cultivation of more effective tree species, such as, for example, a pear, in the zones of HC removal. Finally, given the dual usefulness of the forest as a fuel source and as an absorber of the most common greenhouse gas, enterprises should cultivate forest areas to absorb HC in their immediate vicinity. In addition, in order to receive HC produced in winter, warehouses with dry ice reserves should be located next to enterprises and with other HC removal zones.

Claims (1)

A method of removing carbon dioxide from the atmosphere using solar energy stored in wood materials, in which the latter is burned with oxygen to produce heat and a mixture of gases containing carbon dioxide, the latter is isolated from the mixture and dry ice is obtained from it, characterized in that dry ice delivered to the forest area, regasified, distributed over the area of the zone and mixed with air to obtain an excess average daily carbon dioxide concentration of 0.05 to 0.2% by volume absorbed as a result of photosynthesis and trees, which are then burned.