JP3929005B2 - Combustion apparatus and combustion method - Google Patents

Description

ここで（１）式は４２０℃以下の温度で特に起きやい。
【００１４】
（２）式は４５０℃以下の温度で特に起きやすい。
（３）式は５５０℃以下の温度で特に起きやすい。
すなわち、これらの炭酸ガス吸収材を燃焼部２に添加することによって、燃焼反応が進行している高温・高圧水中から炭酸ガスを吸収・除去することが出来き、結果的に燃焼反応を促進する事ができる。この超臨界水と燃料が反応ている液体から直接炭酸ガスを除去する事燃焼反応が促進される事は発明者らが新たに発見した事実であり、本発明に至ることができた。こうして反応が促進される事によって、排出される炭酸ガスの総量を、燃焼時に随時炭酸ガスを除去しない場合と比べて大幅に低減する事が出きる。
【００１５】
これらの材料は、30％以上50％以下の気孔率を有する多孔質体とすることが好ましく、その多孔質体の形態としては、直径10mm以上50mm以下のディスク状のもの、あるいは一辺の長さが10mm以上50mm以下の立方体に近い形態が挙げられる。除去部５では分離部３で回収した固形物の中から先述した炭酸ガス吸収材のみを回収するために、ＳｉＯ２，Ａｌ２Ｏ３などの燃焼に伴う灰の成分を除去する。ここでは、前記炭酸ガス吸収材と灰の成分の比重差を利用しても良いし、形態の差を利用して分離してもよい。望ましくはあらかじめ前記炭酸ガス吸収材を、ディスク状の形態の場合は直径20mm以上50mm以下の大きさに成形し、また、立方体の形態の場合は一辺の長さが20mm以上50mm以下の大きさに成形しておくと、元々微粉状で供給される石炭の燃焼生成物との形態の違いを明確に得ることが出来、例えば前記20mmより小さい開口を有するステンレスの穴明き板の上を流動させるだけで容易に灰の成分だけを除去することが出来る。
【００１６】
再生部６は、前記炭酸ガス吸収材を加熱して炭酸ガスを放出させ、再度利用できるように再生させる。一気圧の純ガスとして炭酸ガスを回収することを想定すると、加熱温度としては、500 ℃以上900 ℃以下が望ましく、特に好ましくは700 ℃以上820 ℃以下である。
【００１７】
以上の構成によれば、炭酸ガスとの反応によって炭酸リチウムを生成する化合物が燃焼部に添加されていることにより、燃焼排出ガス中から炭酸ガスを効率よく除去することが可能となり、環境中への炭酸ガス放出を大幅に削減することができる。
【００１８】
またさらに、前記反応装置内部で炭酸ガスが直ちに除去されることにより、前記反応装置内部での炭酸ガスの蓄積を防ぐことが出来、結果として燃焼反応そのものの進行を促進することが可能となる。
【００１９】
【実施例】
（実施例１〜３）
図１に示す構成の燃焼装置を作成した。混合部１での給炭量を毎時２７０Ｋｇとし、燃焼部２の温度・圧力条件は550 ℃、230 気圧に設定し、表１に示す時間だけ燃料を保持する間欠燃焼とした。保持時間を１分、３分、８分と変えて夫々を実施例１〜３とした。ここで、この温度条件を維持するために燃焼部２の周囲を流通させた冷却水７の流量から蒸気ドラムに提供した熱量を算出し、各実施例の熱出力として表１に示した。添加部４では、気孔率42％、直径25mm、厚さ10mmのディスク状に成形したリチウムジルコネートを炭酸ガスの吸収材として毎時３．２トン添加した。除去部５ではステンレスメッシュによって吸収材と灰分を分離し、分離された灰分については熱重量分析により未反応の燃料成分を定量し表１に併記した。
【００２０】
【表１】

【００２１】
再生部６では、分離回収した前記炭酸ガス吸収材を810 ℃に昇温し、１気圧の純炭酸ガスとして回収した。分離部３の排気中の炭酸ガス量と再生部６で回収された炭酸ガス量を定量して同じく表１に併記した。
【００２２】
（比較例１〜３）
図２に示す構成の燃焼装置を作成した。以下の装置の説明は、図1 と同一部分は同一番号を付しその詳細を省略した。
【００２３】
この図２の燃焼装置は、図１で示した燃焼装置とは炭酸ガス吸収材を燃焼部に添加しない構造になっている点が異なる。この燃焼装置を使用して実施例１〜３と同一の保持時間を設定した例を比較例１〜３とした。
【００２４】
即ち、混合部１での給炭量を毎時２７０Ｋｇとし、燃焼部２の温度・圧力条件は550 ℃、230 気圧に設定し、表１に示す時間だけ燃料を保持する間欠燃焼とした。ここで、この温度条件を維持するために燃焼部２の周囲を流通させた冷却水７の流量から蒸気ドラムに提供した熱量を算出し、実施例の熱出力として表１に示した。分離部３では戻り水と灰分を分離し、分離された灰分については熱重量分析により未反応の燃料成分を定量し表１に併記した。分離部３の排気中の炭酸ガス量を定量して同じく表１に併記した。
【００２５】
（比較例４）
図３に示す構成の燃焼装置を作成した。混合部１での給炭量を毎時２７０Ｋｇとし、燃焼部２の温度・圧力条件は550 ℃、230 気圧に設定し、表１に示す時間だけ燃料を保持する間欠燃焼とした。ここで、この温度条件を維持するために燃焼部２の周囲を流通させた冷却水７の流量から蒸気ドラムに提供した熱量を算出し、実施例の熱出力として表１に示した。分離部３では戻り水と灰分を分離し、分離された灰分については熱重量分析により未反応の燃料成分を定量し表１に併記した。アルカノールアミンをもちいる炭酸ガス回収部８を分離部３の排気系に接続して、排気中の炭酸ガスを選択吸収し大気中に放出される炭酸ガス量と回収部８で回収される炭酸ガスを定量して同じく表１に併記した。
【００２６】
表１に示すように実施例１〜３の燃焼装置は、比較例１〜４の燃焼装置に比べ、燃料の燃焼部２における滞在時間に相当する燃焼部２における保持時間が短い条件でも未反応の燃料成分が大幅に低減され、燃焼反応の確実な進行が確保され発熱を最大限に回収できることが判る。また、同時に大気中に排出される炭酸ガスの量も大幅に抑制されている事も分かる。
【００２７】
【発明の効果】
以上詳述したように、本発明によれば炭酸ガス蓄積を防いで超臨界水と燃料との燃焼反応を促進する事によって、炭酸ガスの総排出を抑制することができる。
【図面の簡単な説明】
【図１】本発明の実施例１〜３に用いた燃焼装置のブロック図
【図２】本発明の比較例１〜３に用いた燃焼装置のブロック図
【図３】本発明の比較例４に用いた燃焼装置のブロック図
【符号の説明】
１…混合部
２…燃焼部
３…分解部
４…添加部
５…除去部
６…再生部
７…冷却水[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a combustion apparatus and a combustion method that uses a heat of a fuel such as coal / heavy oil that contains a relatively large amount of substances that can become air pollutants with high efficiency and without releasing the pollutants.
[0002]
[Prior art]
Plants that generate electricity by generating steam from the heat generated by reacting high-pressure and high-pressure water at 200 atmospheres and 400 ° C or higher with coal and other fuels are being studied as an application technology of so-called supercritical water. . These plants have great expectations in that, despite the impurities contained in the fuel, the oxidation reaction can be carried out without releasing harmful substances such as sulfides into the atmosphere and the reaction heat can be extracted. Collecting. However, for carbon dioxide emissions, which are the main cause of global warming, there is no way to separate and recover, and since the reaction vessel is sealed at high pressure and the oxidation reaction proceeds, the reaction vessel proceeds. There is a problem that carbon dioxide accumulates inside and inhibits the reaction.
[0003]
[Problems to be solved by the invention]
The conventional combustion apparatus has a problem that carbon dioxide accumulates in the reaction vessel and inhibits the reaction because the reaction vessel is sealed at a high pressure and the vessel is sequentially sealed to advance the oxidation reaction. Furthermore, there is a problem that the amount of carbon dioxide gas, which is a main cause of global warming, is large.
[0004]
The present invention has been made to solve the above-described conventional problems. Carbon dioxide is directly recovered from high-temperature and high-pressure water at 200 atm and 400 ° C. or more to prevent accumulation of carbon dioxide in the combustion section. An object of the present invention is to provide a highly efficient combustion apparatus that suppresses the discharge of carbon dioxide gas.
[0005]
Combustion apparatus of the present invention, produced in a combustion apparatus having a combustion unit for generating heat and carbon dioxide are reacted by storing supercritical water and fuel to the combustion portion, the metal carbonate by reaction between the carbon dioxide It is characterized by comprising a chemical absorbing material.
[0006]
It said metal carbonate is lithium carbonate, said supercritical water, or 200 atm can be a 400 ° C. or higher.
[0007]
Furthermore, the regeneration part which removes a carbon dioxide gas from the said chemical absorber, and the addition part which returns the reproduced | regenerated chemical absorber to the said combustion part can be provided.
[0008]
As the chemical absorbent, a lithium compound mainly composed of a metal oxide selected from iron, nickel, and zirconia can be used .
[0009]
In the combustion method of the present invention, a reaction heat and carbon dioxide gas are formed from a mixture of supercritical water and fuel in the combustion section, and the carbon dioxide gas is reacted with a chemical absorbent in the combustion section to form a metal carbonate. And a process.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the combustion apparatus according to the present invention will be described in detail.
For example, as shown in FIG. 1, the combustion apparatus of the present invention is a mixing unit 1 for mixing fuel 18 and water 11, and a combustion for maintaining a mixture of fuel and supercritical water at a high temperature and high pressure of 400 ° C. or higher and 200 atm or higher. Part 2, separation part 3 that separates water after combustion and combustion product 13 is a central component, carbon dioxide absorbent addition part 4 and removal part 5 are added to the periphery thereof, and carbon dioxide absorption is further removed A material regeneration unit 6 and a transport mechanism for returning the regenerated absorbent material to the addition unit 4 are provided. Here, the supercritical water is water that exceeds the critical point of water while being maintained in a high temperature and high pressure environment of, for example, 200 atm and 400 ° C. or higher.
[0011]
Here, the mixing unit 1 may have any form as long as it mixes finely pulverized coal or heavy oil with water and air. The combustion section 2 is a container that holds a mixture of fuel and water at a high temperature and high pressure of 400 ° C. or higher and 200 atm or higher. For example, a booster pump is provided on the inlet side, and a pressure reducing valve is provided on the outlet side. A mechanism like this is required. On the outer surface of the container, heat medium channels 71 and 72 such as water are installed to remove heat generation and convert the heat into steam, for example, for power generation. The separation unit 3 is a so-called air-water separator, and separates the solid matter 13 and nitrogen 10 from the depressurized and cooled water, and refluxes the water 11 to the mixing unit 1. At this time, heat may be exchanged with the high-temperature water discharged from the combustion unit 2 to effectively use the heat. Here, 14 is an absorbent material, 15 is carbon dioxide, and 16 and 17 are high-pressure air.
[0012]
In the addition section 4 of the carbon dioxide absorbent, a substance that generates lithium carbonate and selectively absorbs carbon dioxide under the temperature and pressure conditions of the combustion apparatus is added together with, for example, high-pressure air. The carbon dioxide absorbing material may be any material as long as it can selectively absorb carbon dioxide. Specifically, the following method is recommended. That is, a method in which a lithium compound mainly composed of an oxide selected from iron, nickel, and zirconia is used as a chemical absorbent, wherein the lithium compound absorbs carbon dioxide according to the formulas (1) to (3) and vice versa. Carbon dioxide is released by the reaction. This is described as Equation 1.
[0013]
[Expression 1]

Here, the expression (1) is particularly easy to occur at a temperature of 420 ° C. or lower.
[0014]
The formula (2) is particularly likely to occur at a temperature of 450 ° C. or lower.
Equation (3) is particularly likely to occur at temperatures of 550 ° C. or lower.
That is, by adding these carbon dioxide absorbents to the combustion section 2, carbon dioxide can be absorbed and removed from the high-temperature / high-pressure water in which the combustion reaction is proceeding, and as a result, the combustion reaction is promoted. I can do things. The fact that the combustion reaction is promoted by removing carbon dioxide directly from the liquid in which the supercritical water and the fuel are reacted is a fact newly discovered by the inventors, and the present invention has been achieved. By promoting the reaction in this way, the total amount of carbon dioxide discharged can be greatly reduced as compared with the case where carbon dioxide is not removed at any time during combustion.
[0015]
These materials are preferably porous bodies having a porosity of 30% or more and 50% or less, and the form of the porous body is a disk-like one having a diameter of 10 mm or more and 50 mm or less, or the length of one side. Is a shape close to a cube of 10 mm or more and 50 mm or less. The removal unit 5 removes ash components accompanying combustion, such as SiO 2 and Al 2 O 3, in order to collect only the carbon dioxide absorbent described above from the solids collected by the separation unit 3. Here, the specific gravity difference between the carbon dioxide absorbent and the ash component may be used, or separation may be performed using the difference in form. Desirably, the carbon dioxide absorbing material is preliminarily formed into a size of 20 mm to 50 mm in the case of a disk shape, and the length of one side is set to a size of 20 mm to 50 mm in the case of a cube. If molded, the difference in form from the combustion product of coal originally supplied in fine powder form can be clearly obtained, for example, it flows on the stainless steel perforated plate having an opening smaller than 20 mm. Only the ash component can be easily removed.
[0016]
The regenerating unit 6 heats the carbon dioxide absorbing material to release carbon dioxide and regenerates it so that it can be used again. Assuming that carbon dioxide gas is recovered as a pure gas at one atmosphere, the heating temperature is preferably 500 ° C. or higher and 900 ° C. or lower, and particularly preferably 700 ° C. or higher and 820 ° C. or lower.
[0017]
According to the above configuration, the compound that generates lithium carbonate by the reaction with carbon dioxide gas is added to the combustion section, so that carbon dioxide gas can be efficiently removed from the combustion exhaust gas, and into the environment. Carbon dioxide emission can be significantly reduced.
[0018]
Furthermore, carbon dioxide gas is immediately removed inside the reaction apparatus, so that accumulation of carbon dioxide gas inside the reaction apparatus can be prevented, and as a result, the progress of the combustion reaction itself can be promoted.
[0019]
【Example】
(Examples 1-3)
A combustion apparatus having the configuration shown in FIG. 1 was prepared. The amount of coal supply in the mixing section 1 was set to 270 kg / hour, the temperature and pressure conditions of the combustion section 2 were set to 550 ° C. and 230 atm, and intermittent combustion was performed for holding fuel for the time shown in Table 1. The holding time was changed to 1 minute, 3 minutes, and 8 minutes, respectively, and Examples 1 to 3 were used. Here, in order to maintain this temperature condition, the amount of heat provided to the steam drum was calculated from the flow rate of the cooling water 7 circulated around the combustion section 2, and the heat output of each example is shown in Table 1. In the addition part 4, 3.2 tons of lithium zirconate formed into a disk shape having a porosity of 42%, a diameter of 25 mm, and a thickness of 10 mm was added as an absorbent of carbon dioxide gas per hour. In the removing section 5, the absorbent and the ash were separated by a stainless mesh, and the unreacted fuel components were quantified by thermogravimetric analysis for the separated ash and are also shown in Table 1.
[0020]
[Table 1]

[0021]
In the regeneration unit 6, the carbon dioxide gas absorbent separated and recovered was heated to 810 ° C. and recovered as pure carbon dioxide gas at 1 atm. The amount of carbon dioxide in the exhaust of the separation unit 3 and the amount of carbon dioxide recovered in the regeneration unit 6 were quantified and are also shown in Table 1.
[0022]
(Comparative Examples 1-3)
A combustion apparatus having the configuration shown in FIG. 2 was prepared. In the following description of the apparatus, the same parts as those in FIG.
[0023]
The combustion apparatus of FIG. 2 differs from the combustion apparatus shown in FIG. 1 in that the carbon dioxide absorbent is not added to the combustion section. The example which set the same holding time as Examples 1-3 using this combustion apparatus was made into Comparative Examples 1-3.
[0024]
That is, the amount of coal supply in the mixing unit 1 was set to 270 kg / hour, the temperature and pressure conditions of the combustion unit 2 were set to 550 ° C. and 230 atm, and intermittent combustion was performed for holding fuel for the time shown in Table 1. Here, in order to maintain this temperature condition, the amount of heat provided to the steam drum was calculated from the flow rate of the cooling water 7 circulated around the combustion section 2, and is shown in Table 1 as the heat output of the example. In the separation unit 3, the return water and the ash were separated, and the unreacted fuel components were quantified by thermogravimetric analysis for the separated ash, and are also shown in Table 1. The amount of carbon dioxide in the exhaust gas of the separation unit 3 was quantified and is also shown in Table 1.
[0025]
(Comparative Example 4)
A combustion apparatus having the configuration shown in FIG. 3 was produced. The amount of coal supplied in the mixing section 1 was set to 270 kg / hour, the temperature and pressure conditions of the combustion section 2 were set to 550 ° C. and 230 atm, and intermittent combustion was carried out for holding fuel for the time shown in Table 1. Here, in order to maintain this temperature condition, the amount of heat provided to the steam drum was calculated from the flow rate of the cooling water 7 circulated around the combustion section 2, and is shown in Table 1 as the heat output of the example. In the separation unit 3, the return water and the ash were separated, and the unreacted fuel components were quantified by thermogravimetric analysis for the separated ash, and are also shown in Table 1. A carbon dioxide recovery unit 8 using alkanolamine is connected to the exhaust system of the separation unit 3 to selectively absorb the carbon dioxide in the exhaust and release it into the atmosphere and the carbon dioxide recovered in the recovery unit 8. Are also shown in Table 1.
[0026]
As shown in Table 1, the combustion devices of Examples 1 to 3 are unreacted even under conditions where the holding time in the combustion unit 2 corresponding to the residence time of the fuel in the combustion unit 2 is shorter than the combustion devices of Comparative Examples 1 to 4. It can be seen that the fuel component of the fuel is greatly reduced, the reliable progress of the combustion reaction is ensured, and the heat generation can be recovered to the maximum. At the same time, it can be seen that the amount of carbon dioxide discharged into the atmosphere is greatly reduced.
[0027]
【The invention's effect】
As described above in detail, according to the present invention, the total discharge of carbon dioxide can be suppressed by preventing carbon dioxide accumulation and promoting the combustion reaction between supercritical water and fuel.
[Brief description of the drawings]
FIG. 1 is a block diagram of a combustion apparatus used in Examples 1 to 3 of the present invention. FIG. 2 is a block diagram of a combustion apparatus used in Comparative Examples 1 to 3 of the present invention. Block diagram of the combustion system used for the above
DESCRIPTION OF SYMBOLS 1 ... Mixing part 2 ... Combustion part 3 ... Decomposition part 4 ... Addition part 5 ... Removal part 6 ... Regeneration part 7 ... Cooling water

Claims (5)

In a combustion apparatus having a combustion section that stores and reacts with supercritical water and fuel to generate heat and carbon dioxide, the combustion section includes a chemical absorbent that generates metal carbonate by reaction with the carbon dioxide. Combustion device characterized by that. 2. The combustion apparatus according to claim 1, wherein the metal carbonate is lithium carbonate, and the supercritical water is 200 atm or higher and 400 ° C. or higher.   The combustion apparatus according to claim 1, further comprising: a regeneration unit that removes carbon dioxide gas from the chemical absorbent, and an addition unit that returns the regenerated chemical absorbent to the combustion unit.   The combustion apparatus according to claim 1, wherein the chemical absorbent is a lithium compound mainly composed of an oxide of a metal selected from iron, nickel, and zirconia. Forming a reaction heat and carbon dioxide from a mixture of supercritical water and fuel in the combustion unit, by comprising a step of generating the carbon dioxide to the metal carbonates are reacted with the chemical absorbent in said firing unit A characteristic combustion method.

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