JP3481824B2 - Carbon dioxide recovery method for thermal power generation system - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal power generation system including a plurality of thermal power plants for generating electric power using a fuel containing hydrocarbon as a main component, and in particular, to a thermal power generation system comprising the plurality of thermal power plants. carbonate in a thermal power system adapted for carbon dioxide discharged from the thermal power plant during operation can be collected at low cost
It relates to a gas recovery method . 2. Description of the Related Art In a thermal power plant that generates electric power using a fuel mainly containing hydrocarbons such as coal, oil and natural gas, carbon dioxide gas is discharged as a by-product during operation. Increasing carbon dioxide in the global environment is not preferable because it leads to global warming. Therefore, it is desired to recover carbon dioxide from exhaust gas. As means for separating and recovering carbon dioxide from exhaust gas of a thermal power plant, a separation method using a cellulose acetate membrane, a chemical absorption method using an alkanolamine-based solvent, and the like are known. However, in any of the methods, if most of the carbon dioxide gas discharged from the thermal power plant is to be recovered, the energy consumed for separating the carbon dioxide gas becomes too large, and as a result, the power generation efficiency is reduced. Greatly reduce. For this reason, the fact is that widespread use is hindered. SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and can reduce the amount of energy consumed for carbon dioxide gas separation. It is an object of the present invention to provide a method for recovering carbon dioxide in a thermal power generation system capable of separating and recovering carbon dioxide . [0006] In order to achieve the above object, the present invention generates electric power using a fuel containing hydrocarbon as a main component and separates and recovers carbon dioxide gas generated during operation. carbon dioxide recovered in a thermal power system to have a plurality of thermal power plant including the carbon dioxide gas recovery mechanism
The method is characterized in that the amount of carbon dioxide recovered by the carbon dioxide recovery mechanism of each thermal power plant is in the range of 5 % to 15 % of the amount of carbon dioxide generated during operation. It is preferable that the carbon dioxide gas recovery mechanism uses lithium zirconia as an absorbent. The present invention
The thermal power generation system according to one aspect includes the following elements. That is, as shown in FIG. 1, a plurality of thermal power plants 1 that convert energy derived from coal, oil, or natural gas into electric power are connected to each other by a transmission line 2 or the like to supply electric power to a load. Has adopted. [0009] Each thermal power plant 1 is provided with some carbon dioxide recovery mechanism for separating and recovering carbon dioxide generated during power generation. Thermal power plant 1
In FIG. 2, as shown in FIG. 2, a fuel gas generator 3 for converting a raw material into a fuel gas is provided, and the fuel gas generated by this device is sent to a combustor 4. The carbon dioxide gas recovery mechanism 5 is provided between the fuel gas generator 3 and the combustor 4. Depending on the carbon dioxide recovery mechanism, it may be installed on the downstream side of the combustor 4. As the carbon dioxide gas recovery mechanism 5, for example, a mechanism in which lithiated zirconia which reacts with carbon dioxide to generate a carbonate is arranged so as to be in contact with a fuel gas containing carbon dioxide or an exhaust gas is used. it can. Lithiated zirconia, which is a carbon dioxide gas absorbing material, absorbs carbon dioxide gas according to the equation (1) and releases carbon dioxide gas according to the equation (2). Li ₂ ZrO ₃ + CO ₂ → ZrO ₂ + Li ₂ CO ₃ + heat generation (1) ZrO ₂ + Li ₂ CO ₃ → Li ₂ ZrO ₃ + CO ₂ + endotherm (2) Here, the reaction of the formula (1) is 550 ° C. The reaction of formula (2) is particularly likely to occur at the following temperature, and the reaction of formula (2) is particularly likely to occur at a temperature of 650 ° C. or higher. Lithium zirconia, which is a carbon dioxide absorbent, has, for example, the following form. That is, there are Li ₂ ZrO ₃ particles or Li ₄ ZrO ₄ particles having a particle size of about 0.4 to 1.0 μm, which are mixed with an organic binder and then degreased to form a porous body. As shown in FIG. 3, the container for storing the lithium zirconia preferably functions as a carbon dioxide gas absorbing cylinder. That is, it contains the lithiated zirconia 6 therein and has gas inlets 7a, 7b and gas outlets 8a, 8b, so that the passage of the gas for absorbing the carbon dioxide gas and the passage of the gas for recovering the carbon dioxide gas are performed. It has a structure that can be switched. It should be noted that the number of gas inlets and outlets is not limited as long as the same operation is possible, and the gas inlet and outlet can be implemented by operating a valve or the like. A thermal power generation system according to one aspect includes a plurality of thermal power plants having a carbon dioxide gas recovery mechanism for generating electric power using a fuel containing hydrocarbons as a main component and separating and recovering carbon dioxide gas generated during operation. The amount of carbon dioxide recovered by the carbon dioxide recovery mechanism of each thermal power plant is averaged to a range of 3% to 10% of the amount of carbon dioxide generated during operation of each thermal power plant. I have. Therefore, for example, as shown in FIG.
%, But the cost of separation per unit amount of carbon dioxide gas is greatly reduced as compared with a thermal power generation system configured so that carbon dioxide gas is not separated and recovered at other thermal power plants 9 at all. be able to. [0015] Figure 5 theoretical separation energy is shown requires the carbon dioxide concentration attempts collector capturing carbon dioxide at various recovery from 10% of the mixed gas. As can be seen from this figure, when the concentration is 10%, the separation energy is particularly small in the region where the recovery is 10% or less. Therefore, if the same amount of carbon dioxide is to be recovered, the thermal power generation system according to the first aspect of the present invention is more effective than the system shown in FIG. wherein the range of recovery that towards the system to be current capturing and averaging is more efficient as it is clear. However, theoretical energy necessary to carbon dioxide capturing current is, property is advantageous in the low dose yields are not typical ones, for example, FIG. 5
As an example in the case of concentration of 90% in a tendency to be advantageous to capturing current conversely at a high recovery rate in excess of 60% rather in this case. In the present invention, electric power is generated using a fuel containing hydrocarbon as a main component, and 5% or more and 15% or less of the amount of carbon dioxide gas generated during operation is separated and recovered. Thermal power generation by multiple thermal power plants with carbon dioxide recovery mechanism
Power system, more preferably 6
More than 00 tons of carbon dioxide is removed from the exhaust gas. [0021] [0022] separation mechanism of carbon dioxide in the present invention may be any method as long as it can conveniently carried out,
For example, a method using the above-described lithiated zirconia, which can directly absorb carbon dioxide from a high-temperature gas of about 400 ° C. to 550 ° C., is effective. If the ratio of the amount of carbon dioxide gas recovered by the separation / recovery mechanism to the amount of carbon dioxide gas generated in each thermal power plant is defined as the recovery rate, the recovery rate in each thermal power plant is 5%. If it is less than 1, the effect of suppressing carbon dioxide emission as a whole of the power generation system is not sufficient for the increase in energy consumption, and if the recovery rate exceeds 15%, the carbon dioxide gas separation mechanism becomes complicated and sophisticated, and the equipment involved in the separation is increased. Costs and operating costs increase sharply. Embodiments of the present invention will be described below. First, four types of thermal power plants A to D shown in Table 1 were set as elements constituting the thermal power generation system.
These are generally known coal-fired thermal power plants, and the method of recovering carbon dioxide, the amount of recovered carbon dioxide, and the recovery rate are as shown in Table 1. Here, the Celexol method is a method of physically absorbing carbon dioxide gas using dimethyl ether of polyethylene glycol, and requires a process of once cooling the gas to be introduced to around room temperature. It has a feature that can be catching collection in the recovery rate. Further, LZ method is a method of recovering carbon dioxide using lithium zirconia described above, it is possible to recover the direct carbon dioxide gas from the hot gas, includes a feature that can be implemented a simple capturing current at low cost I have. Table 1 also shows the calculated amount of carbon dioxide per weight of recovered carbon dioxide from the increase in power generation cost due to the addition of the amount of carbon dioxide recovered and the amount of carbon dioxide recovery equipment obtained from the above results. That is, a value obtained by dividing the increased fuel supply amount by the recovered carbon dioxide gas amount compared with the case where the same power generation amount is obtained by the plant A that does not perform carbon dioxide recovery at all is also written as the required fuel increase per recovered carbon dioxide gas amount. are doing. The five thermal power generation systems shown in Table 2 were configured by combining the thermal power plants shown in Table 1. [Table 1] [Table 2] Example 1 As shown in Table 2, a thermal power generation system composed of 11 thermal power plants C alone and having a total power generation of 4.59 million kW was configured. Example 2 As shown in Table 2, a thermal power generation system including a thermal power generation plant C1O group and a D1 group with a total power generation of 4.59 million kW was configured. Example 3 As shown in Table 2, a thermal power generation system composed of 18 thermal power plants and 4 D power plants and having a total power generation of 9.190 million kW was configured. COMPARATIVE EXAMPLE 1 As shown in Table 2, a thermal power generation system having a total power generation of 4.6 million kW composed of thermal power plants Al and B1 was constructed. Comparative Example 2 As shown in Table 2, a thermal power generation system having a total power generation capacity of 4,540,000 kW was constituted by nine thermal power plants A and two B2 power plants. As can be seen from Table 2, when the increase in required fuel per the amount of carbon dioxide recovered based on Plant A, which does not perform carbon dioxide recovery, is compared. In the thermal power generation systems according to the first to third embodiments, a recovery mechanism is provided, and the amount of carbon dioxide gas recovered by these is averaged in the range of 3% to 10% of the amount of carbon dioxide generated in each thermal power plant. However, the recovery cost is about 40% smaller than that of the comparative thermal power generation system. Therefore, in the thermal power generation systems of Examples 1 to 3, the average cost spent on carbon dioxide gas recovery can be significantly reduced as compared with the thermal power generation system of the comparative example. Further, as can be seen from the third embodiment, the above-mentioned effects become more remarkable as the thermal power generation system is increased in scale. As described above, according to the present invention,
It is possible to recover the carbon dioxide contained in the exhaust gas of the thermal power generation system with minimum energy and cost.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram of a thermal power generation system according to an embodiment of the present invention. FIG. 2 is a view of a place where a carbon dioxide gas recovery mechanism is installed in a thermal power plant constituting the system. FIG. 3 is a schematic diagram illustrating an example of a configuration of a carbon dioxide gas recovery mechanism. FIG. 4 is a conceptual diagram of a thermal power generation system serving as a comparative example. FIG. Diagram showing the relationship between the recovery rate and the energy required for it. [Description of References] 1. Thermal power plant 2. Transmission line 3. Fuel gas generator 4. Combustor 5. Carbon dioxide recovery mechanism 6. Lithium zirconia 7a , 7b ... entrance 8a, 8b ... exit

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshihiro Akasaka 1 Toshiba-cho, Komukai, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba R & D Center Co., Ltd. (72) Inventor Toshihiro Tomimatsu No. 1, Toshiba Research and Development Center Co., Ltd. (56) References JP-A-4-112634 (JP, A) JP-A-4-350303 (JP, A) JP-A-8-12314 (JP, A) JP JP-A 8-141357 (JP, A) JP-A 8-155262 (JP, A) JP-A 9-99214 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 53 / 62,53 / 14

Claims (1)

(57) [Claims 1] A plurality of carbon dioxide recovery mechanisms for generating electric power using a fuel containing hydrocarbons as a main component and for separating and recovering carbon dioxide generated during operation. carbon dioxide recovered in a thermal power system to have a thermal power plant
In the method, the amount of carbon dioxide recovered by the above-described carbon dioxide recovery mechanism of each thermal power plant is reduced by 5% of the amount of carbon dioxide generated during operation.
%. A method for recovering carbon dioxide in a thermal power generation system, wherein the range is not less than 15% and not more than 15%.