Patent Application
20130252115
The present invention relates to a hydrocarbon gasification combined generation system including coal or biomass.
An integrated gasification combined cycle (IGCC) means generation in which coal is converted into a synthesis gas, main constituents of which are hydrogen (H2) and carbon monoxide (CO), and then electricity is generated using the synthesis gas.
The largest advantage of using an IGCC is that generation can be performed using a coal resource that is widely spread worldwide and has rich deposits. In addition, the IGCC has high thermal efficiency and thus can reduce the generation quantities of carbon dioxide (CO2), sulfur oxides, nitrogen oxides, and dust per unit generation electric power quantity and has been evaluated as technology having very excellent environmental performance. In addition, the IGCC has been spotlighted as technology of future generation that can be applied to carbon dioxide (CO2) separation storage technology, hydrogen production technology, and a system associated with fuel cells.
In this way, the IGCC has advantages in relation to efficiency and environmental pollution in comparison with thermal power generation using coal according to the related art and can be combined with various fields. However, the IGCC according to the related art has the following problems.
First, in the IGCC according to the related art, coal is gasified by radiant heat of a high temperature furnace in a gasification process of coal, and thus preheating of 1,300° C. to 1,500° C. is required to operate a gasifier. Thus, much time and high cost for preheating the gasifier are required.
Also, since the IGCC according to the related art requires a high pressure of more than 25 atmospheric pressure for gasification, it is very difficult to miniaturize the gasifier and it is also difficult to control the gasifier.
Also, an oxygen generation facility cost required for pure oxygen gasification is 15% of the entire construction cost, and thus high cost for an oxygen generation facility is required.
The present invention is directed to providing a generation system in which, in a generation system for an integrated gasification combined cycle (IGCC), a synthesis gas is produced using a plasma gasifier so that, even when low-quality coal having a high ash content is used, generation can be performed and a 1 atmospheric pressure process is adopted to produce electric power at a low cost.
More preferably, the present invention is directed to providing coal gasification having a high ratio of H2/CO composition using pure steam plasma.
One aspect of the present invention provides a generation system including: a plasma gasifier that combusts pulverized coal or biomass using plasma so as to generate a synthesis gas including hydrogen (H2) and carbon monoxide (CO); an impurity removing device that removes an impurity included in the generated synthesis gas; a gas storage tank in which the synthesis gas, an impurity of which has been removed by the impurity removing device, is stored; and a gas engine that combusts the synthesis gas stored in the gas storage tank so as to produce electricity.
Another aspect of the present invention provides a generation system including: a plasma gasifier that combusts pulverized coal or biomass using plasma so as to generate a synthesis gas including hydrogen (H2) and carbon monoxide (CO); an impurity removing device that removes an impurity included in the generated synthesis gas; a gas storage tank in which the synthesis gas, an impurity of which has been removed by the impurity removing device, is stored; and a solid oxide fuel cell (SOFC) that produces electricity using the synthesis gas stored in the gas storage tank.
According to exemplary embodiments of the present invention, even when low-quality coal having high ash constituents (ash constituents of more than 45%) is used, a synthesis gas can be produced using a gasifier using plasma so that the usage range of coal for generation can be increased.
In addition, according to exemplary embodiments of the present invention, since the synthesis gas is produced in a 1 atmospheric pressure environment, a generation facility can be miniaturized, and the generation facility can be constructed at a low cost. Since a 1 atmospheric pressure process is used, generation can be performed using not a gas turbine but a gas engine or a solid oxide fuel cell (SOFC).
In addition, according to the present invention, even when not coal but biomass is used, gasification can be performed so that the present invention is advantageous in technology and device aspects in comparison with a generation method according to the related art.
Hereinafter, exemplary embodiments of the present invention will be described in detail. However, the present invention is not limited to the exemplary embodiments disclosed below, but can be implemented in various forms.
In the description of the present invention, if it is determined that a detailed description of a known technology related to the invention may unnecessarily obscure the subject matter of the invention, the detailed description will be omitted. In addition, the following terms are terms that are defined in consideration of functions in the present invention and may vary according to user's and operator's intentions or practices. Thus, their definitions should be based on contents throughout the present specification.
A technical spirit of the present invention is determined by the claims, and the following embodiments are just a means of efficiently describing the technical spirit of the present invention to one of ordinary skill in the art.
As illustrated in
The plasma gasifier 102 is a device that generates a synthesis gas including hydrogen (H2) and carbon monoxide (CO) from pulverized coal or biomass using plasma. A detailed configuration of the plasma gasifier 102 will be described below.
The impurity removing device 104 removes an impurity included in the synthesis gas generated by the plasma gasifier 102. The impurity removing device 104 may include a dust removing unit 110 and a sulfur compound removing unit 112, as illustrated in
The gas storage tank 106 is a space in which the synthesis gas, an impurity of which, such as dust or sulfur compounds, has been removed by the impurity removing device 104, is stored. The synthesis gas with a predetermined quantity may be stored in advance in the gas storage tank 106 so as to be used in an initial operation of the generation system 100 illustrated in
The gas engine 108 produces electricity by combusting the synthesis gas stored in the gas storage tank 106. An integrated gasification combined cycle (IGCC) according to the related art is configured to produce electricity using a gas turbine; however, the current embodiment of the present invention is configured to produce a synthesis gas using an 1 atmospheric pressure process and thus is configured to produce electricity by driving the gas engine 108 (not the gas turbine) using the synthesis gas. In this way, when the synthesis gas is produced using the plasma gasifier 102 and the gas engine 108 is driven using the synthesis gas, gas production and electric power production are performed under a 1 atmospheric pressure so that miniaturization can be realized in comparison with the IGCC according to the related art.
An operation of the generation system 100 using the plasma gasifier having the above configuration according to the first exemplary embodiment of the present invention in an energy aspect will now be described below.
First, when general mass constituent ratios of carbon and combustible hydrocarbon included in coal (pulverized coal) that is a raw material are
C:H2:O2=70%:7%:23%,
if the mass constituent ratios are converted into molar ratios,
C:H2:O2=5.83:3.5:1.44,
if the molar ratio of carbon is converted into 1,
C:H2:O2=1:0.6:0.25.
Meanwhile, enthalpy, H, which is required for decomposition of hydrocarbon in which oxygen and hydrogen are contained, is defined by the following equation: H=40 kJ. In this case, hydrocarbon is assumed as compounds, such as polymer hydrocarbon and methanol.
A reaction between carbon and hydrocarbon included in coal inside a plasma torch in the plasma gasifier 102 is as follows:
C+(¼)O2+(0.6)H2+(½)H2O→CO+(1.1)H2
In this case, enthalpy change is defined by the following equation: ΔH=10.4 kJ.
Meanwhile, a combustion reaction inside the gas engine 108 is
CO+(1.1)H2+(1.05)O2→CO2+(1.1)H2O,
and enthalpy change in this combustion reaction is defined by the following equation: ΔH=−549 kJ.
If an electric power production efficiency of the gas engine 108 is about 32%, electric power production quantity per 1 mole of carbon is defined by the following equation: 549 kJ×0.32=175.7 kJ. In this case, required electric energy is defined by the following equation: 40+10.4=50.4 kJ. Thus, pure electric power production quantity is defined by the following equation: 175.7−50.4=125.3 kJ.
Meanwhile, the generation system 100 using the plasma gasifier according to the first exemplary embodiment of the present invention may further include the plasma gasifier 102, heat exchangers 114, 116, and 118 that convert the synthesis gas produced by the plasma gasifier 102 or heat generated from the gas engine 108 into steam, and a steam turbine 120 that produces electricity using the steam generated by the heat exchangers 114, 116, and 118. In this way, heat generated in the generation system 100 is converted into electricity using the steam turbine 120 so that efficiency of the generation system 100 can be improved.
As illustrated in
Among them, the plasma gasifier 102, the impurity removing device 104, and the gas storage tank 106 illustrated with the same reference numerals as those of
In the present embodiment, unlike the first embodiment, electric power is produced using the SOFC 202. The SOFC 202 is a device that converts chemical energy into electric energy using a hydrocarbon fuel, has a very high energy conversion efficiency, has high stability, and is easy to handle, because it uses a solid. In the IGCC according to the related art, a process is performed under a high pressure and thus the usage of an SOFC is not possible. However, in the present embodiment, like in the above-described first embodiment, since a process is performed under a 1 atmospheric pressure, generation using the SOFC 202 can be performed.
Meanwhile, the generation system 200 using the plasma gasifier according to the second exemplary embodiment of the present invention may further include the plasma gasifier 102, heat exchangers 114 and 116 that convert heat generated from a synthesis gas produced by the plasma gasifier 102 into steam, and a steam turbine 120 that produces electricity using the steam generated by the heat exchangers 114 and 116, like in the first embodiment. In this way, heat generated in the generation system 200 is converted into electricity using the steam turbine 120 so that efficiency of the generation system 100 can be improved.
Also, even in the present embodiment, like in the first embodiment, at an initial stage, the SOFC 202 is driven using the synthesis gas stored in the gas storage tank 106 to produce initial electric power, and the plasma gasifier 102 is driven using the produced electric power so that the entire system can operate.
Hereinafter, the plasma gasifier used in the first embodiment and the second embodiment of the present invention will be described. The plasma gasifier 102 used in the first and second embodiments of the present invention includes at least one plasma generator 300 and a gasification reactor 800 in which the synthesis gas is generated by plasma generated by the plasma generator 300.
As illustrated in
The power unit 302 supplies electric power required to drive the plasma generator 300.
The electromagnetic wave oscillator 304 is connected to the power unit 302 and oscillates electromagnetic waves by receiving electric power from the power unit 302. An electromagnetic wave oscillator that oscillates electromagnetic waves having a frequency range of 902 to 928 MHz or 886 to 896 MHz is used in the present invention, and preferably, electromagnetic waves having a frequency of 915 MHz or 896 MHz are oscillated using the electromagnetic wave oscillator 304.
The circulatory system 306 is connected to the electromagnetic wave oscillator 304, outputs the electromagnetic waves oscillated by the electromagnetic wave oscillator 304 and simultaneously, dissipates electromagnetic wave energy that is reflected with impedance mismatch so as to protect the electromagnetic wave oscillator 304.
The tuner 308 induces impedance matching by adjusting intensities of incident waves and reflected waves of the electromagnetic waves output from the circulatory system 306 such that an electric field induced by the electromagnetic waves is the maximum in the discharge tube 312.
The waveguide 310 transmits the electromagnetic waves input from the tuner 308 to the discharge tube 312. In the present invention, the size of the waveguide 310 has a relation with the frequency of the electromagnetic waves oscillated by the electromagnetic wave oscillator 304. If the frequency of the electromagnetic waves oscillated by the electromagnetic wave oscillator 304 decreases, the wavelength of the electromagnetic waves increases. Thus, when electromagnetic waves having different frequencies are introduced into a waveguide having a predetermined size, electromagnetic waves having a lower frequency than a cutoff frequency of the waveguide are not introduced into the waveguide. That is, the waveguide serves as a kind of high pass filter. Thus, the size of the waveguide is determined depending on a used frequency.
The cutoff frequency of the waveguide is defined by the following equation 1:
where fc is a cutoff frequency, c is the velocity of light, a is a latitudinal size of a waveguide, b is a longitudinal size of the waveguide, and m and n are electromagnetic wave mode numbers in the waveguide.
In the present invention, a waveguide with the latitudinal size a of 25 cm*the longitudinal size b of 12.5 cm is used. Also, in the present invention, the electromagnetic waves are oscillated in a TE10 mode. Thus, in this case, m is 1, and n is 0. The cutoff frequency of the waveguide 310 according to the present invention is calculated by the following equation 2:
As described above, the electromagnetic wave oscillator 304 according to the present invention oscillates the electromagnetic waves having the frequency range of 902 to 928 MHz or 886 to 896 MHz. Thus, the frequency of the electromagnetic waves is higher than the cutoff frequency of the waveguide 310. Thus, the electromagnetic waves oscillated by the electromagnetic wave oscillator 304 are not cut off but are introduced into the waveguide 310.
Meanwhile, a cutoff wavelength at the waveguide 310 is defined by the following equation 3:
A wavelength λg of the waveguide 310 when an oscillation frequency at the electromagnetic wave oscillator 304 is 915 MHz is defined by the following equation 4:
Equation 4
λg=λ/[1−(fc/f)2]1/2=32.8/[1−(0.6/0.915)2]1/2=43.5 cm (4).
When the discharge tube 312 is inserted spaced apart from an end of the waveguide 310 by ¼ of the wavelength λg in the waveguide 310, a position in which the discharge tube 312 is inserted, is about 11 cm (≈43.5/4) from the end of the waveguide 310.
As illustrated in
The discharge tube 312 generates plasma from the electromagnetic waves supplied by the electromagnetic wave supply unit 322 and a mixture gas including steam and oxygen, and gasifies solid coal using the generated plasma so as to generate a synthesis gas. The synthesis gas is mainly composed of carbon monoxide (CO) and hydrogen (H2) and includes an impurity, such as sulfur compounds, in addition to CO and H2.
As described above, the mixture gas injected into the discharge tube 312 stabilizes the generated plasma and forms a swirl in the discharge tube 312 so as to protect inner walls of the discharge tube 312 from a high-temperature plasma flame. In general, it is very difficult to generate plasma using only pure steam in an atmospheric state, and even when plasma is generated, plasma may be easily extinguished. Thus, in the present invention, the mixture gas is composed by adding oxygen or air to pure steam that is a base so that plasma can be more stably generated in comparison with a case that pure steam is used.
In addition, it is also possible to control a constituent ratio of the synthesis gas generated by controlling a mixture ratio of steam (H2O) and oxygen (O2) in the mixture gas.
The following reaction occurs in the discharge tube 312 by the plasma.
(1) Combustion by oxygen (oxidation reaction): C+O2→CO2
The present reaction is a heat dissipation reaction and occurs very fast. Through this reaction, heat required for gasification can be supplied.
(2) Gasification by oxygen (partial oxidation reaction): C+½O2→CO
The present reaction is also a heat dissipation reaction and occurs very fast.
(3) Gasification by carbon dioxide (CO2) (Boudouard reaction): C+CO2→2CO
The present reaction is a heat absorption reaction and is slower than the oxidation reaction.
(4) Gasification by steam: C+H2O→CO+H2
The present reaction is a heat absorption reaction and is slower than the oxidation reaction. This reaction is preferred at a high temperature and under a low pressure.
(5) Gasification by hydrogen: C+2H2→CH4
The present reaction is a heat dissipation reaction and is slower than the oxidation reaction. However, in case of a high pressure, exceptionally, the speed of this reaction increases.
(6) Water gas shift (WGS) reaction (Dussan reaction): CO+H2O→H2+CO2
The present reaction is slightly a heat absorption reaction and occurs fast. A ratio of CO to H2 of the synthesis gas is affected by the present reaction.
(7) Methane generation reaction: CO+3H2→CH4+H2O
The present reaction is a heat dissipation reaction and occurs very slowly.
Next, the gas supply unit 314 injects the mixture gas into the discharge tube 312 in the form of a swirl, and the coal supply unit 316 supplies solid coal (pulverized coal) to the plasma generated in the discharge tube 312. Detailed configurations of the gas supply unit 314 and the coal supply unit 316 will be described below.
The ignition unit 318 includes a pair of electrodes disposed in the discharge tube 312 and supplies initial electrons for generating plasma through the pair of electrodes.
The gas discharge unit 320 is provided at an upper end of the discharge tube 312 and discharges the synthesis gas generated by the plasma to the outside. The synthesis gas discharged by the gas discharge unit 320 is purified by the impurity removing unit 104, is stored in the gas storage tank 106, and then is supplied to the gas engine 108.
First, as illustrated in
The gas supply unit 314 is formed to surround the discharge tube 312 from a lower end of the discharge tube 312, and the coal supply unit 316 is formed to surround an upper end of the gas supply unit 314, i.e., a portion of the discharge tube 312 in which plasma is formed.
In
As illustrated in
The steam supply tube 600 and the oxygen supply tube 602 may be formed in the gas supply unit 314 in appropriate numbers as needed.
The steam supply tube 600 and the oxygen supply tube 602 are supplied to the discharge tube 312 so that the mixture gas of supplied steam and oxygen rotates along an inner circumferential surface of the discharge tube 312 in the form of a swirl. To this end, as illustrated in
As illustrated in
The coal supply tube 700 may be formed in the coal supply unit 316 in an appropriate number as needed, and like in the steam supply tube 600 and the oxygen supply tube 602, a predetermined number of coal supply tubes 700 may be arranged in the coal supply unit 316 around the discharge tube 312 at the same intervals.
In an embodiment of the present invention, the coal supply tube 700 may be supplied to the discharge tube 312 so that supplied powdery coal rotates along the inner circumferential surface of the discharge tube 312 in the form of a swirl. To this end, as illustrated in
In another embodiment of
Carbon dioxide (CO2) may be used as a carrier gas for supplying coal (pulverized coal) into the discharge tube 312. The synthesis gas generated in the plasma generator 300 according to the present invention includes a considerable amount of carbon dioxide (CO2) in addition to hydrogen (H2) and carbon monoxide (CO). Thus, when CO2 is separated from the synthesis gas and is reused as the carrier gas for transferring coal, coal can be efficiently transferred to plasma in the discharge tube 312 and simultaneously, environment pollution caused by emission of CO2 in the air can also be prevented. In addition, the mixture gas of oxygen and steam may be used as the carrier gas, like in the gas supply unit 314, and pure steam or oxygen may also be used as the carrier gas.
While the invention has been shown and described with reference to certain exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit.
Therefore, the claim scope of the present invention should not be limited to the exemplary embodiments disclosed, and should be defined by the appended claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2010-0121234 | Dec 2010 | KR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/KR2010/008633 | 12/3/2010 | WO | 00 | 5/31/2013 |
