JP2003020486A - Coal gasification equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent condensation of inorganic compounds at the heat recovery unit and the char recovery unit of coal gasification equipment. SOLUTION: This coal gasification equipment is equipped with a coal gasification furnace, the heat recovery unit, the char recovery unit and a feeder line. The heat recovery unit recovers heat in generated gas generated in the coal gasification furnace. The char recovery unit recovers char contained in the generated gas exhausted from the heat recovery unit and returns recovered char to the coal gasification furnace. The feeder line feeds a second inorganic compound for converting a first inorganic compound contained in the generated gas and condensed at least at either one temperature of the heat recovery unit or the char recovery unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for gasification of coal, and more particularly to a technology for product gas containing an inorganic compound having high condensability.

[0002]

2. Description of the Related Art In recent years, it has been attempted to use a gas produced by gasifying coal or heavy oil residue as a chemical raw material, a fuel for power generation, or a gas for a fuel cell. In gasification, fuels such as low-quality coal, biomass and petroleum coke are being diversified. In particular, IGCC, which is an integrated coal gasification combined cycle power plant that uses coal residue as fuel, is an IPP business that sells electricity to electric power companies with power generation facilities. Became.

In the integrated coal gasification combined cycle power generation, a national project for commercial machines is underway, but in order to respond to the increasing environmental assessment, exhaust gas of organic and inorganic substances generated in the gasification furnace, Attention is paid to the drainage.

In the gasification of petroleum coke as a raw material due to the diversification of fuel, an inorganic compound is added to prevent the ash of petroleum coke from adhering to the gasification furnace wall ( JP-A-8-143875). In addition, there is also a problem of inorganic compounds exhibiting condensability in the subsequent equipment of the gasification furnace, and particularly in char recycling of coal gasification combined cycle power generation, sufficient measures against condensable inorganic compounds have not been taken.

Coal gasification is the production of flammable gas by supplying raw material coal together with an oxidizing agent to a gasification furnace under high temperature and high pressure. The produced gas is used as a fuel gas for a gas turbine or the like after the heat is recovered in the heat recovery section. The unburned char contained in the product gas discharged from the heat recovery unit is recovered by the heat recovery unit and the cyclone and the char recovery unit in the subsequent flow. The char after recovery is recycled to improve the efficiency of coal gasification, and is supplied into the furnace from the char burner in the lower stage of the gasification section of the gasification furnace. The ash is discharged as molten slag from the bottom of the gasification furnace to the outside of the furnace.

[0006]

However, when coal is gasified, inorganic compounds such as sodium and potassium may be generated. These inorganic compounds may be discharged together with the generated gas and may be condensed in the heat recovery unit or the char recovery unit. That is, these inorganic compounds have lower melting points than the pure compounds due to their composition. For example, when sodium and potassium are equimolar carbonates, the melting point is lowered to about 600 ° C. When these inorganic compounds become liquid or solid in the heat recovery section, they adhere to the heat transfer tube and promote the adhesion of char to the heat transfer tube, resulting in deterioration of heat transfer performance. Moreover, these inorganic compounds adhering to the heat transfer tube are returned to the gasification furnace together with the char recovered in the heat recovery section, and become gas again to flow into the heat recovery section. Also, when a filter is used in the char recovery unit, if inorganic compounds such as sodium and potassium are condensed in the filter, corrosion is promoted depending on the material of the filter, leading to an increase in the filter differential pressure, which hinders continuous operation. Come here.

An object of the present invention is to prevent the inorganic compound from condensing in the heat recovery section or the char recovery section.

[0008]

In order to solve the above-mentioned problems, a coal gasifier according to the present invention comprises a coal gasification furnace and heat for recovering heat in the product gas produced in the coal gasification furnace. A recovery unit, a char recovery unit that recovers char contained in the produced gas discharged from the heat recovery unit and returns the char to the coal gasification furnace, and at least the heat recovery unit and the char recovery unit included in the produced gas. And a supply unit that supplies a second inorganic compound that converts a first inorganic compound that exhibits a condensable property at one temperature into a nonvolatile inorganic compound.

With such a structure, the second inorganic compound contained in the generated gas and having a condensable property at the temperature of at least one of the heat recovery part and the char recovery part is changed to a non-volatile inorganic compound. By supplying the inorganic compound from the supply means, the first inorganic compound can be discharged as slag from the lower part of the gasification section of the gasification furnace.

The first inorganic compound is at least one of a sodium compound and a potassium compound, and the second inorganic compound is at least one of alumina and silica-alumina. In this way, since the first inorganic compound, the sodium compound or the potassium compound, is an alkaline compound, it reacts with alumina, which is an amphoteric oxide, or silica alumina, which is a mixture of an amphoteric oxide and an acidic compound. A non-volatile inorganic compound that can be discharged as slag in a gasification furnace can be obtained, which is preferable.

Further, if a detecting means for detecting the first inorganic compound contained in the produced gas is provided, and the second inorganic compound is supplied when the first inorganic compound is detected by the detecting means. Since the second inorganic compound is supplied when the first inorganic compound is detected, the supply amount of the second inorganic compound can be reduced, which is preferable.

If the coal gasifier comprises a coal gasifier, and a supply means for supplying at least one of alumina and silica-alumina to the coal gasifier, the coal gasifier is a coal gasifier. It is preferable that the condensable inorganic compound contained in the generated gas generated can be converted into a non-volatile inorganic compound and discharged as slag in the gasification furnace.

If the supply means is a supply means provided in the lower burner of the gasification furnace, the nonvolatile inorganic compound having a high melting point can be obtained by supplying from the lower burner at a temperature higher than that of the upper burner. Is preferable because it can be discharged as slag.

If the supply means is a supply means provided in the line of the char burner from the char recovery section to the char burner of the gasification furnace, the first inorganic compound is
Since it is collected together with the char, by supplying the second inorganic compound to the line of the char burner, it becomes a non-volatile inorganic compound in the gasification furnace and can be discharged as slag.

The supply amount of the second inorganic compound is
The molar ratio of the first inorganic compound to the first inorganic compound is 100 times or more.

Further, if the detection means is provided on the downstream side of the product gas flowing out from the char recovery unit, since it is the product gas after the char recovery, it hardly contains char and the first inorganic compound Can be easily detected.

The second inorganic compound is supplied when the detecting means detects the amount of the first inorganic compound equal to or more than a predetermined value.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a coal gasifier to which the present invention is applied will be described below with reference to FIG. FIG. 1 is a block diagram showing a conceptual configuration of an embodiment of a coal gasification apparatus to which the present invention is applied. As shown in FIG. 1, the coal gasifier of the present embodiment has a gasification furnace 1 for converting coal into a combustible gas under high temperature and high pressure together with an oxidizer. The gasification furnace 1 includes an upper burner 3, a lower burner 5, and a char burner 7. The high-temperature generated gas generated in the gasification furnace 1 is sent to the heat recovery unit 11 equipped with a heat transfer tube that generates steam, and heat is recovered there. The heat-recovered product gas is sent to the cyclone 13, where the coarse-grained char contained in the gas is recovered. The generated gas from the cyclone 13 is sent to a char recovery unit 15 formed using a filter that recovers fine-grained char, and the char contained in the gas is recovered. Heat recovery unit 1
The char recovered by 1, the cyclone 13 and the char recovery unit 15 is sent to the char burner 7 of the gasification furnace 1 through the line 19 of the char burner. The produced gas from which the char is recovered by the char recovery unit 15 is sent to the water washing unit 21, where hydrogen chloride and ammonia contained in the produced gas and other trace elements are removed. Next, the produced gas is sent to the COS conversion section 23, where the carbonyl sulfide (COS) contained in the produced gas is converted into hydrogen sulfide (H ₂ S). The produced gas is sent from the COS conversion unit 23 to the wet gas purifier 25, where hydrogen sulfide is concentrated and separated to produce hydrogen-free product gas, and hydrogen sulfide is concentrated to a high concentration C.
It is divided into a regeneration gas containing O ₂ . The produced gas containing no hydrogen sulfide is sent to the gas turbine 45 and used as fuel. The regenerated gas is mixed with fuel 27 such as LPG, LNG, or light oil and air 29, and is sent to a H ₂ S combustor 31 where H ₂ S is burned and combustion gas containing sulfur trioxide (SO ₃ ). Become. This combustion gas is sent to the heat exchanger 33 and heat-exchanged, and the temperature becomes 300 ° C. or higher. The heat-exchanged combustion gas is sent to the packed tower 35, where dilute sulfuric acid is sprayed and cooled to 60 to 80 ° C. to be a gas to be treated. The gas to be processed is sent to the demister 37 of the gas-liquid separator, and the sulfuric acid mist contained in the gas is removed. The to-be-processed gas from which the sulfuric acid mist is removed is sent to the desulfurization device 39, where it is desulfurized by the limestone gypsum method and recovered as gypsum 41 to be rendered harmless. The detoxified gas is the chimney 43
Is discharged to the atmosphere. The produced gas sent to the turbine 45 as fuel is recovered in heat by the exhaust heat recovery unit 47 after combustion and is exhausted from the chimney 43 to the atmosphere.

Next, the features of the present invention will be described.
As described in the problem to be solved by the present invention, in the coal gasifier, when inorganic compounds such as sodium and potassium are generated during gasification of coal, these are discharged together with the generated gas to recover the heat recovery unit 11 and the char. It may be condensed in the part 15. The condensed inorganic compound adheres to the heat transfer tube of the heat recovery unit 11 and also promotes the adhesion of char to cause a decrease in heat transfer performance. In addition, when inorganic compounds such as sodium and potassium are condensed in the char recovery unit 15, corrosion is promoted depending on the material of the filter, which causes an increase in the filter differential pressure, which hinders continuous operation. Moreover, these inorganic compounds are recovered together with the char, become a gas in the gasification furnace 1, and flow into the heat recovery section 11 and the char recovery section 15 again.

In order to solve this problem, the present invention is characterized in that alumina is supplied from the alumina supply means 9 through the lower burner 5. That is, the coal supplied from the upper burner 3 and the lower burner 5 of the gasification furnace 1 becomes a combustible product gas containing carbon monoxide, hydrogen and the like under high temperature and high pressure together with the oxidizing agent. When inorganic compounds such as sodium and potassium are present in the produced gas, these inorganic compounds have a melting point lower than that of a pure compound due to their composition. For example, sodium,
If potassium is an equimolar carbonate, the melting point drops to about 600 ° C. Therefore, these inorganic compounds may become liquid and solid in the heat recovery part 11. When the liquid inorganic compound adheres to the heat transfer tube,
This promotes the adhesion of char to the heat transfer tube, resulting in a decrease in heat transfer performance. Further, even if these inorganic compounds are recovered together with the char, they are returned to the gasification furnace 1 to be gas again and circulated to the heat recovery section 11. In addition, when inorganic compounds such as sodium and potassium are condensed on the filter of the char recovery unit, the pressure difference of the filter is increased, which hinders continuous operation.

Therefore, when alumina supplying means 9 is provided in the lower burner 5 and alumina is supplied, inorganic compounds such as sodium and potassium are converted into non-volatile inorganic compounds.
This can prevent condensation in the heat recovery unit 11 and the char recovery unit 15. On the other hand, the converted inorganic compound is
It is melted in the gasification furnace 1 and can be discharged as slag from the lower part of the gasification furnace 1.

Although alumina is added in the above example, the present invention is not limited to this, and silica alumina or the like may be used. That is, since inorganic compounds such as sodium and potassium generated in the gasification furnace 1 are alkaline compounds, they react with alumina, which is an amphoteric oxide, or silica alumina, which is a mixture of an amphoteric oxide and an acidic compound, resulting in gasification. This is because it becomes a non-volatile inorganic compound that can be discharged in the furnace 1. For example, when the inorganic compound generated in the gasification furnace 1 is sodium oxide (Na ₂ O) as shown in the following formula (1), alumina (A
This is because by supplying l ₂ O ₃ ), sodium aluminate (NaAlO ₂ ) which is a nonvolatile inorganic compound is formed. Na ₂ O + Al ₂ O ₃ → 2NaAlO ₂ (1) Here, the amount of alumina or silica-alumina to be supplied needs to be, for example, equal to or more than 100 times the molar amount of the inorganic compound of sodium. However, alumina or silica-alumina may be supplied when the heat recovery performance of the heat transfer tube tends to decrease.

On the other hand, when inorganic compounds such as sodium and potassium are concentrated, the vapor pressure of these inorganic compounds rises, and the concentration of the condensable inorganic compounds contained in the produced gas passing through the filter of the char recovery unit 15 increases. To do. Therefore, by detecting the concentration of the inorganic compound in the generated gas discharged from the char recovery unit 15, the char recovery unit 15 can be detected.
It is possible to detect the condensation of the inorganic compound in the filter. Therefore, a detection unit 17 is provided in the middle of the flow path of the generated gas from the char recovery unit 15 to the water washing unit 21 to detect the amount of the inorganic compound in the gas by extracting a part of the generated gas. For the detection unit 17, for example, a light scattering type dust monitor or the like is used. That is, when this generated gas is introduced to the detection unit 17 at the atmospheric temperature, the condensable inorganic compound becomes mist or solid, and can be detected. Alumina or silica-alumina can be supplied when the mist or solid exceeds a predetermined set value. The alumina supply means 9 provided in the lower burner 5 of the gasification furnace 1 includes a detector 17
It is connected with a signal line to control the supply.

The test results when alumina or the like is actually supplied will be described below. (Test 1) When charcoal and an oxidizer were supplied from the upper and lower burners and char recycling was performed, the heat transfer characteristics of the heat recovery part were as low as 18 W / m ² K. Therefore, the amount of sodium and potassium inorganic compounds concentrated in the gasifier is 50
When double-molar alumina was supplied from the lower burner and soot blowing was carried out, and when the characteristics of the heat recovery part were statically determined and evaluated, the external heat transfer coefficient was as high as 30 W / m ² K. (Test 2) In Test 1 described above, when the amount of alumina to be supplied was less than equimolar to the inorganic compounds of sodium and potassium, it was ineffective, but when the amount was changed from equimolar to 100 times, the heat transfer coefficient outside the tube was improved. did. There was no change in improvement when the amount exceeded 100 times. (Test 3) In the above Test 1, when zeolite was added as silica alumina instead of alumina, the external heat transfer coefficient increased to 32 W / m ² K. (Test 4) In Test 1 above, when corundum was used instead of alumina, the external heat transfer coefficient was 31 W /
It was as high as m ² K. (Test 5) When charcoal and an oxidizing agent were supplied from the upper and lower burners and char recycling was carried out, inorganic compounds such as sodium and potassium were concentrated on the filter used in the char recovery unit. At this time, the value on the dust monitor increased.
When the inorganic compounds such as sodium and potassium in the ash component deposited on the char become 15% or more, the char recovery unit outlet temperature 4
At 00 ° C, the filter had alkali corrosion. This value can be set as a set value for supplying alumina or silica-alumina.

As described above, by supplying alumina, silica alumina, etc. from the lower burner 5, the inorganic compounds such as sodium and potassium generated in the gasification furnace 1 are converted into non-volatile inorganic compounds, and the gasification furnace 1 Since it can be discharged as slag, the heat recovery section 11 and the char recovery section 15 can be prevented from condensing.

In this embodiment, the lower burner 5 is provided with the alumina supply means 9, but the present invention is not limited to this. An alumina supply unit may be provided so that an inorganic compound such as sodium or potassium is converted into a nonvolatile inorganic compound by the supplied alumina and can be melted and discharged as slag. For example, as shown in FIG. 2, the alumina supplying means may be provided in the line 19 of the char burner. Alumina is supplied to the line 19 of the char burner in order to convert inorganic compounds such as sodium and potassium recovered with char into non-volatile inorganic compounds. Since the char burner is arranged at the lower position of the gasification furnace, it is at a high temperature like the lower burner. Therefore, the inorganic compounds of sodium and potassium are converted into non-volatile inorganic compounds by alumina, melted and discharged from the gasification furnace 1 as slag, so that they are not condensed in the heat recovery unit 11 or the char recovery unit 15. Further, the char burner 7 may be provided with the alumina supply means 9. In these cases too,
Silica alumina may be supplied instead of alumina.

[0027]

As described above, according to the present invention,
It is possible to prevent the inorganic compound from condensing in the heat recovery unit or the char recovery unit.

[Brief description of drawings]

FIG. 1 is a block diagram showing a conceptual configuration of an embodiment to which the present invention is applied.

FIG. 2 is a block diagram showing a conceptual configuration of a modified example of the embodiment to which the present invention is applied.

[Explanation of symbols]

1 gasification furnace 3 Upper burner 5 Lower burner 7 Char Burner 9 Alumina supply means 11 Heat recovery section 13 cyclone 15 Char collection department 17 Detector 19 lines

Continued front page    (72) Inventor Kunikatsu Yoshida             Babcock Hitachi 3-36 Takaracho, Kure City, Hiroshima Prefecture             Kure Institute Co., Ltd. (72) Inventor Eiji Yamaguchi             Babcock Hitachi 6-9 Takaracho, Kure City, Hiroshima Prefecture             Kure Office Co., Ltd.

Claims (4)

[Claims] 1. A coal gasification furnace, a heat recovery unit for recovering heat in the generated gas generated in the coal gasification furnace, and a char contained in the generated gas discharged from the heat recovery unit. A char recovery unit for returning to the coal gasification furnace, and a first inorganic compound contained in the produced gas and exhibiting condensability at a temperature of at least one of the heat recovery unit and the char recovery unit are converted into a nonvolatile inorganic compound. A coal gasifier comprising a supply means for supplying a second inorganic compound. 2. The coal gasifier according to claim 1, wherein the first inorganic compound is at least one of a sodium compound and a potassium compound, and the second inorganic compound is at least one of alumina and silica-alumina. 3. The detection device according to claim 1 or 2, further comprising a detection unit that detects the first inorganic compound contained in the generated gas, and the detection unit detects the first inorganic compound when the first inorganic compound is detected. A coal gasifier characterized in that the inorganic compound 2 is supplied. 4. A coal gasifier comprising a coal gasification furnace and a supply means for supplying at least one of alumina and silica-alumina to the coal gasification furnace.