Coal blending method for adjusting adaptability of raw material coal of gasification furnace by utilizing ash of gasification furnace

Abstract

According to the coal blending method for adjusting the adaptability of the raw material coal of the gasification furnace by utilizing the ash of the gasification furnace, provided by the invention, the raw material coal which cannot be used as coal for gasification of the entrained-flow bed can be blended with the ash of the gasification furnace to obtain blended coal which can be used as coal for gasification of the entrained-flow bed. The method comprises the following steps: mixing gasification furnace ash into the gasification furnace feed coal so that the coal ash characteristics of the obtained mixed coal meet the following requirements: 1.0 lt, 1.0 lt, 1.0 lt, 1.0 lt, 1.0 lt, 1.0 lt, 1.0 lt, 1.0 lt and 1.0 lt; w (SiO2 + Al2O3) / W (CaO + Fe2O3 + MgO) lt; 5.0, 0.70 lt, 5.0, 0.70 lt; w (CaO) / W (Fe2O3) lt; 2.20 DEG C, and the coal ash flowing temperature of the blended coal is 1100-1450 DEG C; the raw material coal of the gasification furnace is the raw material coal which does not meet the requirements of coal for gasification of the entrained-flow bed.

Description

Technical Field

[0001] The invention relates to the technical field of coal gasification, and in particular to a coal blending method for adjusting the adaptability of raw coal of a gasifier by utilizing gasifier ash. Background Art

[0002] Coal quality is crucial to the long-term stable operation of an entrained flow gasifier. Usually, each entrained flow gasification technology can only adapt to a specific type of coal, which places higher requirements on the quality of coal entering the gasifier, thereby increasing the cost of coal for gasification. However, due to the instability of market coal sources (market supply shortages, changes in coal seam quality, coal mine depletion, etc.), the phenomenon of mismatch between gasification coal and gasifiers often exists, and due to cost issues, the gasification process often uses higher-priced coal types mixed with cheaper coal types to form entrained flow gasification coal to ensure the matching of coal and furnace. For gasification coal, the key issue that affects whether the coal can be used in a gasifier is its coal ash characteristics, because the quality of the coal ash characteristics directly affects whether the gasifier can discharge slag smoothly, thereby affecting the stability of the gasifier operation. For coal types that cannot guarantee smooth slag discharge, it is generally necessary to adjust through coal blending. In addition, coal gasification ash accounts for a large proportion of coal chemical solid waste. Gasification ash is divided into fine ash and coarse ash. Generally speaking, coarse ash has a lower carbon content (less than 5%), while fine ash has a higher residual carbon content (up to 60%). Generally speaking, alkaline oxides tend to be present in fine ash, while acidic oxides tend to be present in coarse ash. The utilization of gasification ash is also a topic of great concern.

[0003] At present, the method for adjusting the characteristics of the coal ash entering the furnace is mainly solved by coal blending, and the related methods are as follows:

[0004] Chinese patent CN201510965171.2 discloses a coal blending method for gasifier coal, including the steps of blending at least two kinds of coal to obtain coal for gasifier, wherein the flow temperature of the coal ash of at least two kinds of coal used for blending is greater than 1300°C, and the R value of the ash content of the coal for gasifier is obtained by detection and calculation; the amount of the at least two kinds of coal used for blending is such that the R value of the ash content of the obtained coal for gasifier is 150-220. The shortcomings of this coal blending method are: its purpose is limited to solving the coal with high ash melting point, that is, it requires that the flow temperature of the coal ash of at least two kinds of coal is greater than 1300°C, the coal types for blending are relatively single, and the cost of coal blending is relatively high.

[0005] Chinese patent CN201210193133.6 discloses a coal blending method suitable for Shell pulverized coal pressurized gasification, which is to mix coal with an ash content higher than 21.08% with petroleum coke, and the amount of coal and petroleum coke required is that the ash content of the mixture after uniform mixing is lower than 21.08%. The disadvantage of this coal blending method is that it is mainly aimed at Shell pulverized coal pressurized gasification technology, and has specific requirements for gasification raw materials, namely coal with an ash content higher than 21.08% and petroleum coke, which is not universal.

[0006] Chinese patent CN201010137851.2 discloses a coal blending method suitable for Texaco water-coal slurry pressurized gasification coal, using high ash melting temperature coal (i.e. coal ash melting temperature>1500℃) and low ash melting temperature coal that is difficult to slurry (i.e. coal ash melting temperature<1300℃) as raw materials for coal blending, wherein the blending ratio of high ash melting temperature coal is 10-60%, and the blending ratio of low ash melting temperature coal that is difficult to slurry is 40-90%, and the coal is evenly blended to meet the requirements of Texaco water-coal slurry gasification. The disadvantage of this coal blending method is that the coal blending method is mainly aimed at Texaco water-coal slurry pressurized gasification technology, and puts forward specific requirements for gasification raw materials, i.e. coal with coal ash melting temperature>1500℃ and coal ash melting temperature<1300℃ as raw materials, and the coal quality requirements for blending are relatively high, and the coal blending cost is also high.

[0007] It can be seen that the existing coal blending methods are mostly targeted at specific coal types, with low applicability and high coal blending costs. Therefore, it is necessary to find a coal blending method for gasifier coal with strong universality and low cost to solve the long-standing coal-furnace matching problem. Summary of the invention

[0008] The present invention provides a coal blending method for adjusting the adaptability of raw coal of a gasifier by using gasifier ash and a blended coal obtained by the coal blending method, and also provides the use of the gasifier ash. By adopting the method of the present invention, raw coal that cannot be used as coal for entrained flow gasification can be blended and prepared with the gasifier ash to obtain blended coal that can be used as coal for entrained flow gasification, which can improve the adaptability of raw coal that does not meet the requirements of coal for entrained flow gasification, solve the "coal-furnace" matching problem; at the same time, the gasifier ash can be turned into treasure.

[0009] To achieve the purpose, the present invention provides the following technical solutions:

[0010] On the one hand, the present invention provides a coal blending method for adjusting the adaptability of raw coal of a gasifier by using gasifier ash, the method comprising:

[0011] By blending the ash slag of the gasifier into the raw coal of the gasifier so that the ash characteristics of the blended coal obtained meet the following requirements: 1.0 < W(SiO2 + Al2O3) / W(CaO + Fe2O3 + MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the ash flow temperature of the blended coal is 1100 - 1450 °C;

[0012] The W(SiO2 + Al2O3) is the sum of the mass percentages of SiO2 and Al2O3 in the ash of the blended coal, the W(CaO + Fe2O3 + MgO) is the sum of the mass percentages of CaO, Fe2O3 and MgO in the ash of the blended coal, and the W(CaO) and W(Fe2O3) are the mass percentages of CaO and Fe2O3 in the ash of the blended coal respectively;

[0013] The raw coal of the gasifier refers to the raw coal that does not meet the requirements for the coal used in the entrained flow gasifier.

[0014] In the present invention, by blending the ash slag of the gasifier into the raw coal that does not meet the requirements for the coal used in the entrained flow gasifier, so that its ash characteristics simultaneously meet 1.0 < W(SiO2 + Al2O3) / W(CaO + Fe2O3 + MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20 and the flow temperature is 1100 - 1450 °C. On the one hand, it is beneficial to obtain a wider operating temperature range of the gasifier, which is beneficial to further broaden the operation window on the basis of the original operating temperature range of the raw coal in the gasifier, and improve the operation flexibility and safety; on the other hand, it can improve the adaptability of these raw coals that cannot be directly used in the entrained flow gasifier, so that they can be used as the coal for the entrained flow gasifier, that is, the blended coal can be applicable to at least one kind of entrained flow gasifier, such as applicable to the water coal slurry gasifier and / or the dry pulverized coal gasifier. For the specific blending amount of the ash slag of the gasifier, it is subject to enabling the raw coal to meet the above ash characteristic requirements after the above blending.

[0015] In some embodiments, the ash characteristics of the raw coal used do not simultaneously satisfy 1.0 < W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO) < 5.0 and 0.70 < W(CaO) / W(Fe2O3) < 2.20. For such raw coal, the blending method of this invention is used to blend the ash slag of the gasifier, so that the ash characteristics of the obtained blended coal simultaneously satisfy 1.0 < W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flowing temperature is 1100-1450°C, which can significantly improve the coal quality characteristics of such raw coal and can further significantly broaden its gasification operation window. In some embodiments, the ash characteristics of the raw coal that does not meet the requirements for coal used in entrained flow gasification simultaneously satisfy 1.0 < W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20. Using the blending method of this invention to blend the ash slag of the gasifier, so that the ash characteristics of the obtained blended coal simultaneously satisfy 1.0 < W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flowing temperature is 1100-1450°C, can also further significantly improve the coal quality characteristics of such raw coal and can further significantly broaden its original gasification operation window.

[0016] Preferably, by blending the ash slag of the gasifier into the raw coal of the gasifier, the ash characteristics of the obtained blended coal further satisfy the following requirements: the ash content is 6-20 wt%. By adjusting the blending amount of the ash slag of the gasifier, the blended coal that meets the above ash content requirements can be obtained. Controlling the ash content of the blended coal after blending the ash slag of the gasifier within this preferred range, on the one hand, it will not cause a large amount of slag discharge in the entrained flow gasifier with liquid slag discharge due to too high ash content, nor will it cause too much ash to absorb more heat to achieve liquid slag discharge, resulting in a reduction in gasification performance; on the other hand, it will not cause the inability to form a slag film or slag layer on the inner wall of the gasifier due to too low ash content, resulting in rapid damage to the inner wall of the gasifier.

[0017] Preferably, by blending the gasifier ash into the gasifier raw coal, the ash characteristics of the blended coal also meet the following requirements: the Fe2O3 content in the ash is ≤18wt%, preferably 8-18wt%. By adjusting the amount of gasifier ash added, a blended coal that meets the above-mentioned iron oxide content requirements can be obtained. The iron oxide content in the ash of the blended coal is controlled within the above-mentioned range, and the raw coal will not be easily reduced to elemental iron in a reducing atmosphere due to the excessively high Fe2O3 content of the raw coal, causing liquid slag crystallization and slag blockage. Specifically, the blended coal is used in an entrained flow gasifier, and the entrained flow gasifier is a water-coal slurry gasifier or a dry coal powder gasifier; preferably, the water-coal slurry gasifier is a hot fireplace.

[0018] In some implementations, when the entrained flow gasifier used is a water-coal slurry gasifier, the ash fluidity temperature of the blended coal obtained by the blending is 1100-1350°C.

[0019] By using the above-mentioned coal blending method of the present invention, by blending the gasifier ash into the gasifier raw coal, a blended coal having the following coal ash characteristics can be obtained:

[0020] T 25 <1300℃,T 2.5 >1300℃, and T 2.5 -T 25 ≥50℃(e.g. ≥100℃, ≥150℃,

[0021] ≥200℃), the blended coal meeting this requirement can be well applied to water-coal slurry gasifier;

[0022] Or, T 25 <1400℃,T 2.5 >1400℃, and T 2.5 -T 25 ≥50℃ (e.g. ≥100℃, ≥150℃, ≥200℃), the blended coal meeting this requirement can be well applied to the dry pulverized coal gasifier;

[0023] Wherein T 25 is the temperature corresponding to the viscosity of 25 Pa·s after the coal ash mixed with coal forms liquid slag, T 2.5 It is the temperature corresponding to the viscosity of 2.5 Pa·s after the coal ash of the blended coal forms liquid slag. By using the coal blending method of the present invention, the raw coal is blended and prepared using the gasification furnace ash and slag to obtain the blended coal with the above characteristics.

[0024] The present invention proposes a coal blending method for raw coal that cannot meet the coal requirements for entrained flow gasification by using gasifier ash. Specifically, the raw coal that does not meet the coal requirements for entrained flow gasification targeted by the present invention refers to raw coal having at least one of the following characteristics a)-f):

[0025] a) The flow temperature of fly ash is lower than 1100℃;

[0026] b) Raw coal with a ash flow temperature higher than 1350°C for entrained-flow coal-water slurry gasification, or raw coal with a ash flow temperature higher than 1450°C for entrained-flow dry coal gasification;

[0027] c) Fe2O3 content in the coal ash is higher than 18wt%;

[0028] d) ash content is less than 6wt%;

[0029] e)T 25 ≥1400℃;

[0030] f)T 2.5 -T 25 <50℃;

[0031] Among them, the T 25 is the temperature at which the viscosity of the coal ash of the raw coal is 25 Pa·s after forming liquid slag, T 2.5 It is the temperature corresponding to when the viscosity of the coal ash of the raw coal is 2.5 Pa·s after forming liquid slag.

[0032] The ash melting point (including deformation temperature DT, softening temperature ST, hemispherical temperature HT, and flow temperature FT) is related to the chemical composition of the raw coal. If the ash melting point of the raw coal is too low (lower than 1100°C), it is easy to not hang slag during the actual gasification process, and it is impossible to form a slag film or slag layer on the inner wall of the gasifier, thereby causing rapid damage to the inner wall of the gasifier. If the ash melting point of the raw coal is too high (for water-coal slurry gasification, it means higher than 1350°C, for dry coal powder gasification, it means higher than 1450°C), more coal and oxygen are needed to increase the temperature of the gasifier in order to ensure that the ash is liquid and the liquid slag is discharged smoothly. Therefore, the raw coal with the above characteristics a) and b) is difficult to be directly used in the gasifier.

[0033] The Fe2O3 content of the raw coal is relatively high (higher than 18wt%). If such raw coal is directly used in the gasifier, it is easily reduced to elemental iron in a reducing atmosphere, causing the liquid slag to crystallize, thereby causing the viscosity of the liquid slag to rise suddenly and rapidly, causing slag blockage. Therefore, there are obstacles for the raw coal with the above characteristics c) to be used as coal for the gasifier.

[0034] If the ash content of the raw coal is too low (less than 6 wt%), it is impossible to form a slag film or slag layer on the inner wall during the actual gasification process, which will cause rapid damage to the inner wall of the gasifier. Therefore, it is also difficult to directly feed the raw coal with the above-mentioned characteristic d) into the gasifier.

[0035] In the art, the ash of the raw coal 25 ≥1400 °C, and it is generally considered that it is difficult to be used as coal for entrained flow gasification. And T 2.5 -T 25 <50 °C. Because it has a narrow operating temperature range of the gasifier, it leads to great operation difficulty, causes inconvenience in the operation of the gasifier and brings greater safety risks, so it is also difficult to be directly applicable to the gasifier.

[0036] In some embodiments, the raw coal that does not meet the requirements of coal for entrained flow coal water slurry gasification used in the coal blending method of the present invention has the following ash characteristics: the flowing temperature is lower than 1100 °C (characteristic a)), and the oxide composition satisfies 1.0 < W(SiO2 + Al2O3) / W(CaO + Fe2O3 + MgO) < 5.0 and 0.70 < W(CaO) / W(Fe2O3) < 2.20. In some embodiments, the raw coal that does not meet the requirements of coal for entrained flow gasification used in the coal blending method of the present invention has the following ash characteristics: the oxide composition does not simultaneously satisfy 1.0 < W(SiO2 + Al2O3) / W(CaO + Fe2O3 + MgO) < 5.0 and 0.70 < W(CaO) / W(Fe2O3) < 2.20, and at the same time has any one or more of the foregoing characteristics a)-f). By using the coal blending method of the present invention to blend the gasifier ash slag into these raw coals, the blended coal obtained can simultaneously meet the requirements of the ash characteristics of the blended coal mentioned above, and a blended coal with significantly improved coal quality characteristics can be obtained, which can be made suitable for use as coal for entrained flow gasification.

[0037] Specifically, in the present invention, the gasifier ash slag is selected from at least one of gasification fine slag and gasification coarse slag, and preferably includes at least gasification fine slag.

[0038] As is well known in the art, gasification coarse slag refers to the solid residue collected after the coal ash is discharged from the slag discharge port of the gasifier in liquid form at high temperature and cooled, while gasification fine slag refers to the solid residue collected after the fly ash and unreacted carbon carried by the synthesis gas are washed and purified by the synthesis gas. Among them, in general, alkaline oxides tend to exist in the gasification fine slag, and acidic oxides tend to exist in the gasification coarse slag. In some embodiments, the ash content of the gasification fine slag used is, for example, 20-80%, and the ash composition mainly includes, for example, 20-40% SiO2, 10-30% Al2O3, 10-25% Fe2O3, 10-20% CaO and <3% MgO, etc.; the ash content of the gasification coarse slag used is, for example, 80-99.9%, and the ash composition mainly includes, for example, 30-50% SiO2, 10-30% Al2O3, 5-15% Fe2O3, 5-20% CaO and <3% MgO, etc. The above composition of the gasification fine slag and the gasification coarse slag is taken as an example.

[0039] The inventors have discovered that by adding gasification fine slag and / or gasification coarse slag to raw coal that does not meet the requirements for coal used in an entrained flow gasifier, the ash characteristic requirements of the aforementioned blended coal can be met and the resulting blended coal can be used as coal for entrained flow gasification, that is, it can be suitable for at least one type of entrained flow gasifier.

[0040] The inventors have found that for raw coal with the above-mentioned characteristic f), the coal blending method of the present invention can be used to broaden the gasifier operating temperature range (i.e., gasifier operating window) by blending the raw coal with gasifier ash and meeting the above-mentioned coal ash characteristic requirements for blended coal, thereby improving the operating flexibility and the safety of gasifier operation. The inventors have also found that even if the raw coal does not have the above-mentioned characteristic f), the coal blending method of the present invention can significantly broaden the T range originally possessed by the raw coal. 2.5 -T 25 The temperature difference widens the operating temperature range of the gasifier, improving the operating flexibility and safety of the gasifier.

[0041] Preferably, when performing the blending, the gasification fine slag is first blended into the raw coal of the gasifier, and when the blended coal obtained after blending cannot meet the requirements of the coal ash characteristics of the blended coal, the gasification coarse slag is blended into the raw coal of the gasifier. When performing the blending, the specific amounts of the gasification fine slag and the gasification coarse slag are based on the requirement that the blended coal can meet the coal ash characteristics required to be met by the blended coal.

[0042] Preferably, when the ash flow temperature of the raw coal of the gasifier is higher than 1350 °C, at least one kind of gasifier ash slag satisfying W(CaO) / W(Fe2O3) > 1.0 is used for the blending; wherein, W(CaO) and W(Fe2O3) are the mass percentages of CaO and Fe2O3 in the ash composition of the gasifier ash slag respectively. For example, when using gasification fine slag and gasification coarse slag simultaneously for blending and proportioning the raw coal of the gasifier, if the ash flow temperature of the raw coal of the gasifier is higher than 1350 °C, at least one of the used gasification fine slag and gasification coarse slag needs to satisfy W(CaO) / W(Fe2O3) > 1.0. The inventors of the present invention have found that adopting this preferred method is beneficial to reducing the ash melting point of the blended coal after blending, and helps to obtain a blended coal satisfying an ash flow temperature of 1100 - 1450 °C.

[0043] Furthermore, by using the coal blending method of the present invention, the raw coal unsuitable for entrained flow gasification is blended and proportioned with gasifier ash slag (gasification fine slag and / or gasification coarse slag) to make it simultaneously satisfy the aforesaid ash characteristics requirements of the blended coal, that is, simultaneously satisfy 1.0 < W(SiO2 + Al2O3) / W(CaO + Fe2O3 + MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flow temperature is 1100 - 1450 °C. Preferably, it also simultaneously satisfies an ash content of 6 - 20 wt%, and more preferably also simultaneously satisfies that the Fe2O3 content in the coal ash is ≤ 18 wt%; the obtained blended coal will have significantly improved coal quality characteristics suitable for entrained flow gasifiers compared with the raw coal, and can be suitable for use as coal for entrained flow gasification.

[0044] The present invention also provides a blended coal for an entrained flow gasifier, which is obtained by blending using the coal blending method described above.

[0045] The present invention also provides a new use of gasifier ash slag, that is, using gasifier ash slag to blend the raw coal of the gasifier to obtain a blended coal suitable for entrained flow gasification, and the raw coal of the gasifier refers to the raw coal that does not meet the requirements of coal for entrained flow gasification; preferably, the gasifier ash slag is used to blend the raw coal of the gasifier by the coal blending method described above to obtain the blended coal suitable for entrained flow gasification. That is, the adaptability of the raw coal of the gasifier is adjusted by using gasifier ash slag, and the coal quality characteristics of the raw coal of the gasifier are improved. Specific descriptions of the gasifier ash slag and the coal blending method are all referred to the previous description and will not be repeated here.

[0046] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0047] 1) The coal blending method of the present invention utilizes gasifier ash (gasification fine slag and / or gasification coarse slag) to blend raw coal that does not meet the requirements for coal used in an entrained flow gasifier, so that it meets the coal ash characteristic requirements mentioned in the present invention. The raw coal that does not meet the use requirements can be used as coal for entrained flow gasification, which not only solves the "coal-furnace" matching problem, but also allows the cheap raw coal to be used as coal for entrained flow gasification, thereby reducing the cost of coal entering the furnace.

[0048] 2) The coal blending method of the present invention can fully utilize the surplus value of the gasifier ash, solve the environmental hazard problem caused by the gasifier ash, and fully recover the carbon in the ash, which belongs to the recycling of solid waste and turns waste into treasure.

[0049] 3) The coal blending method of the present invention does not need to prepare multiple raw coals to obtain coal suitable for the fluidized flow gasifier. Compared with the scheme of using two or more types of coal for coal blending in the prior art, the blended coal (i.e., coal for fluidized flow gasification) obtained by the coal blending method of the present invention has a lower carbon content and a significant carbon reduction effect.

[0050] 4) The present invention proposes a new use of gasifier ash (gasification fine slag and / or gasification coarse slag), and also provides a new method for blending coal for fluidized bed gasification. The gasifier ash can be used to improve the coal quality characteristics of raw coal that does not meet the requirements of fluidized bed gasification coal, so that it can be used as fluidized bed gasification coal after being blended with gasifier ash. DETAILED DESCRIPTION

[0051] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs. Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used.

[0053] The percentages used in the embodiments of the present invention are all by mass unless otherwise specified.

[0054] In the following embodiments, the flow temperature FT of the coal ash is measured by an ash melting point instrument according to GB / T 219-2008 (Determination of Fusibility of Coal Ash); the temperature T corresponding to the viscosity of 25 Pa·s after the coal ash forms liquid slag is 25 And the temperature T corresponding to the viscosity of 2.5 Pa·s after the coal ash forms liquid slag 2.5The test results are obtained by the power industry standard DL / T660-2007 (test method for high temperature viscosity characteristics of ash). The ash content is tested by GB / T 212-2008 (industrial analysis method of coal), the ash composition of coal samples before and after blending is tested by GB / T 1574-2007 (coal ash composition analysis method), and the ash composition of gasification fine slag and gasification coarse slag is tested by GB / T 1574-2007 (coal ash composition analysis method).

[0055] In the following embodiments, if the raw coal involved has any one or more of the following characteristics a)-f), it is considered to be a type of coal that does not meet the requirements for coal for entrained flow gasification:

[0056] a) The flow temperature FT of the fly ash is lower than 1100℃;

[0057] b) Raw coal with a ash flow temperature FT higher than 1350°C for entrained-flow coal-water slurry gasification, or raw coal with a ash flow temperature higher than 1450°C for entrained-flow dry coal gasification;

[0058] c) Fe2O3 content in the coal ash is higher than 18wt%;

[0059] d) ash content is less than 6wt%;

[0060] e)T 25 ≥1400℃;

[0061] f)T 2.5 -T 25 <50℃.

[0062] The following examples involve a total of 4 types of coal (i.e., raw coal) that do not meet the requirements for entrained flow gasification coal, and also involve gasification coarse slag and gasification fine slag samples from a gasifier. The analysis results of each sample are shown in Tables 1 and 2 (oxides of elements such as Sr, Zn, Mn, and Ba are not included).

[0063] Table 1 Analysis results of coal sample ash content, flow temperature FT and ash composition

[0064]

[0065] Table 2 Ash content and ash composition analysis results of gasification fine slag and coarse slag of a gasifier

[0066]

[0067] Example 1

[0068] The 1# coal was mixed with gasification fine slag and gasification coarse slag in a mass ratio of 85:5:10. The coal ash characteristics before and after mixing are shown in Table 3 below:

[0069] Table 3

[0070]

[0071]

[0072] As can be seen from Table 1 and Table 3, for Coal Type 1 before blending, the ash flow temperature FT is relatively low (<1100 °C), and its gasification performance is low, making it unsuitable as a coal type for entrained flow gasification and not meeting the national standard GB / T 29722-2013 (Technical Conditions for Raw Coal for Entrained Flow Gasification). This coal type can neither meet the requirements for coal used in water slurry entrained flow gasification (for a hot hearth, the required flow temperature FT ≥ 1100 - 1350 °C) nor the requirements for coal used in dry pulverized coal entrained flow gasification (the required flow temperature FT ≥ 1100 - 1450 °C).

[0073] In this embodiment, by blending Coal Type 1 with gasification fine slag and gasification coarse slag in a ratio of 85:5:10, the ash characteristics of the resulting blended coal simultaneously meet the following requirements: 1.0 < W(SiO2 + Al2O3) / W(CaO + Fe2O3 + MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flow temperature is 1100 - 1350 °C, and the ash content is 6 - 20 wt%. As can be seen from Table 3, the ash flow temperature of the blended coal obtained after blending is increased to 1223 °C, fully meeting the flow temperature suitable for water slurry gasification. In addition, the temperature difference between T 2.5 -T 25 also increases from the original 104 °C to 212 °C, and the gasification operation window is significantly widened. This shows that the coal quality characteristics are significantly improved after blending.

[0074] Example 2

[0075] Blend Coal Type 2 with gasification fine slag and gasification coarse slag in a mass ratio of 90:5:5. The ash characteristics before and after blending are shown in Table 4 below:

[0076] Table 4

[0077] Coal ash characteristics Before blending After blending <![CDATA[W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO)]]> 2.88 2.72 <![CDATA[W(CaO) / W(Fe2O3)]]> 2.24 2.02 Ash / wt% (dry basis) 11.18 16.33 <![CDATA[W(Fe2O3) / wt%]]> 6.54 7.38 Flow temperature FT / ℃ 1390 1310 <![CDATA[Temperature T corresponding to a viscosity of 25 Pa·s 25 / ℃]]> 1475 1373 <![CDATA[Temperature T corresponding to a viscosity of 2.5 Pa·s 2.5 / ℃]]> 1583 1575 <![CDATA[T 2.5 -T 25 / ℃]]> 108 202

[0078] As can be seen from Table 1 and Table 4, for Coal Type 2 before blending, the ash flow temperature FT is higher than 1350 °C. According to the national standard GB / T 29722-2013 (Technical Conditions for Raw Coal for Entrained Flow Gasification), this coal type cannot meet the condition of the flow temperature for the hot hearth in water slurry entrained flow gasification (the requirement is ≥ 1100 - 1350 °C), and this coal type is not suitable for coal used in water slurry gasification; also, because the temperature corresponding to T 25 of this coal type is as high as 1475 °C, it is also not suitable for the requirements of coal used in dry pulverized coal entrained flow gasification (the requirement is T 25 <1400 °C).

[0079] In this embodiment, after mixing the No. 2 coal type with gasification fine slag and gasification coarse slag in a ratio of 90:5:5, the ash characteristics of the obtained blended coal simultaneously meet the following requirements: 1.0 < W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flow temperature is 1100 - 1450 °C, and the ash content is 6 - 20 wt%. As can be seen from Table 4, the ash flow temperature of the blended coal obtained after blending is reduced to 1310 °C, and T 25 is reduced from 1475 °C to 1373 °C, fully meeting the requirements of dry pulverized coal gasification. In addition, after blending, the T 2.5 -T 25 temperature difference is also increased from the original 108 °C to 202 °C, and the gasification operation window is also significantly widened. This shows that the coal quality characteristics are significantly improved after blending.

[0080] Example 3

[0081] The No. 3 coal type is mixed with gasification fine slag and gasification coarse slag in a mass ratio of 90:5:5. The ash characteristics before and after blending are shown in Table 5 below:

[0082] Table 5

[0083] Coal ash characteristics Before blending After blending <![CDATA[W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO)]]> 1.69 1.70 <![CDATA[W(CaO) / W(Fe2O3)]]> 2.20 2.05 Ash / wt% (dry basis) 5.86 11.55 <![CDATA[W(Fe2O3) / wt%]]> 9.31 9.87 Flow temperature FT / ℃ 1140 1163 <![CDATA[Temperature T corresponding to a viscosity of 25 Pa·s 25 / ℃]]> 1380 1309 <![CDATA[Temperature T corresponding to a viscosity of 2.5 Pa·s 2.5 / ℃]]> 1514 1515 <![CDATA[T 2.5 -T 25 / ℃]]> 134 206

[0084] Combined with Table 1 and Table 5, it can be seen that the ash content of the No. 3 coal type before blending is relatively low (less than 6 wt%), which is not conducive to slagging on the inner wall of the gasifier and cannot protect the furnace lining, so it is not suitable as coal for entrained flow gasification. In this embodiment, after mixing the No. 3 coal type with gasification fine slag and gasification coarse slag in a ratio of 90:5:5, the ash characteristics of the obtained blended coal simultaneously meet the following requirements: 1.0 < W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flow temperature is 1100 - 1450 °C, and the ash content is 6 - 20 wt%. As can be seen from Table 5, the ash content of the blended coal obtained after blending is increased to 11.55%, and the flow temperature is also increased to 1163 °C. The flow temperature is increased within the allowable flow temperature range, which is conducive to improving the gasification efficiency. In addition, after blending, the T 2.5 -T 25 temperature difference is also increased from the original 134 °C to 206 °C, and the gasification operation window is also widened. This shows that the coal quality characteristics are significantly improved after blending. The blended coal obtained after blending can be used as coal for a dry pulverized coal gasifier.

[0085] Example 4

[0086] Mix the No. 4 coal with gasification fine slag and gasification coarse slag in a mass ratio of 85:5:10. The ash characteristics before and after mixing are shown in Table 6 below:

[0087] Table 6

[0088] Coal ash characteristics Before blending After blending <![CDATA[W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO)]]> 0.98 1.10 <![CDATA[W(CaO) / W(Fe2O3)]]> 1.23 1.23 Ash / wt% (dry basis) 8.95 18.59 <![CDATA[W(Fe2O3) / wt%]]> 18.30 17.5 Flow temperature FT / ℃ 1100 1198 <![CDATA[Temperature T corresponding to a viscosity of 25 Pa·s 25 / ℃]]> 1237 1290 <![CDATA[Temperature T corresponding to a viscosity of 2.5 Pa·s 2.5 / ℃]]> 1289 1456 <![CDATA[T 2.5 -T 25 / ℃]]> 52 166

[0089] Combined with Table 1 and Table 6, it can be seen that the content of Fe2O3 in the No. 4 coal before blending is relatively high (higher than 18 wt%), and it is easily reduced to elemental iron in a reducing atmosphere, causing the crystallization of liquid slag, thus instantaneously causing a sudden rapid increase in the viscosity of liquid slag and resulting in slag blockage. Therefore, it is not suitable as a coal type for entrained flow gasification; and its T 2.5 -T 25 Although it is greater than 50 °C, its gasifier operation window is relatively narrow.

[0090] In this embodiment, after mixing the No. 4 coal with gasification fine slag and gasification coarse slag in a ratio of 85:5:10, the ash characteristics of the obtained blended coal simultaneously meet the following characteristics: 1.0 < W(SiO2 + Al2O3) / W(CaO + Fe2O3 + MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flow temperature is 1100 - 1450 °C, the ash content is 6 - 20 wt%, and the Fe2O3 content ≤ 18 wt%. It can be seen from Table 6 that the Fe2O3 content of the ash of the blended coal obtained after blending is reduced to 17.5%, and the flow temperature is also increased from 1100 °C to 1198 °C, which is beneficial to improving the gasification efficiency. In addition, the T 2.5 -T 25 value is also increased from the original 52 °C to 166 °C, and the gasification operation window is significantly widened, significantly improving the operation flexibility and safety of the gasifier. This shows that the coal quality characteristics are significantly improved after blending. The blended coal obtained after blending can be used as coal for a water coal slurry gasifier.

[0091] Comparative Example 1

[0092] Mix the No. 4 coal with gasification fine slag and gasification coarse slag in a mass ratio of 95:5:0. The ash characteristics before and after mixing are shown in Table 7 below:

[0093] Table 7

[0094] Coal ash characteristics Before blending After blending <![CDATA[W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO)]]> 0.98 0.99 <![CDATA[W(CaO) / W(Fe2O3)]]> 1.23 1.21 Ash / wt% (dry basis) 8.95 10.06 <![CDATA[Fe2O3 content in ash / wt%]]> 18.30 18.42 Flow temperature FT / ℃ 1100 1080 <![CDATA[Temperature T corresponding to a viscosity of 25 Pa·s 25 / ℃]]> 1237 1216 <![CDATA[Temperature T corresponding to a viscosity of 2.5 Pa·s 2.5 / ℃]]> 1289 1252 <![CDATA[T 2.5 -T 25 / ℃]]> 52 36

[0095] As can be seen from Comparative Example 1, after blending the No. 4 coal with gasification fine slag and gasification coarse slag, the coal ash of the obtained blended coal did not simultaneously satisfy the following characteristics: 1.0 < W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flow temperature was 1100-1450 °C, the ash content was 6-20 wt%, and the Fe2O3 content ≤ 18 wt%. The finally obtained blended coal was difficult to meet the coal requirements for entrained flow gasification, specifically manifested as follows: the flow temperature did not increase, but instead further decreased to 1080 °C, and the Fe2O3 content in the coal ash also increased slightly and was higher than 18 wt%. In addition, the temperature difference T 2.5 -T 25 also changed from the original 52 °C to 36 °C, and the gasification operation window was not widened but narrowed.

[0096] In summary, by using the coal blending method of the present invention, the adaptability of raw coal that does not meet the requirements of coal for entrained flow gasification can be adjusted by using gasification fine slag and / or gasification coarse slag. After blending with gasification fine slag and / or gasification coarse slag, the coal ash characteristics of the blended coal simultaneously satisfy 1.0 < W(SiO2+Al2O3) / W(CaO+Fe2O3+MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the flow temperature is 1100-1450 °C (for water coal slurry gasifiers, control the flow temperature to 1100-1350 °C). More preferably, it simultaneously satisfies that the ash content is 6-20 wt%, and further preferably simultaneously satisfies that the Fe2O3 content ≤ 18 wt%, which can significantly improve the coal quality characteristics of the raw coal and enable it to be used as coal for entrained flow gasification.

[0097] Unless otherwise specified, the terms used in the present invention have the meanings commonly understood by those skilled in the art.

[0098] The embodiments described in the present invention are for illustrative purposes only and are not intended to limit the protection scope of the present invention. Those skilled in the art can make various other substitutions, changes, and improvements within the scope of the present invention. Therefore, the present invention is not limited to the above embodiments.

Claims

1. A coal blending method for adjusting the adaptability of raw coal of a gasifier by using gasifier ash, characterized in that: The method includes: Mixing the ash residue of the gasifier into the raw coal of the gasifier so that the ash characteristics of the obtained blended coal meet the following requirements: 1.0 < W(SiO2 + Al2O3) / W(CaO + Fe2O3 + MgO) < 5.0, 0.70 < W(CaO) / W(Fe2O3) < 2.20, and the ash flow temperature of the blended coal is 1100 - 1450 °C; The W(SiO2 + Al2O3) is the sum of the mass percentages of SiO2 and Al2O3 in the ash of the blended coal, the W(CaO + Fe2O3 + MgO) is the sum of the mass percentages of CaO, Fe2O3, and MgO in the ash of the blended coal, and the W(CaO) and W(Fe2O3) are the mass percentages of CaO and Fe2O3 in the ash of the blended coal, respectively; The raw coal of the gasifier refers to the raw coal that does not meet the requirements for coal used in entrained flow gasification.

2. The coal blending method according to claim 1, characterized in that: By mixing the ash residue of the gasifier into the raw coal of the gasifier, the ash characteristics of the obtained blended coal also meet the following requirement: the ash content is 6 - 20 wt%.

3. The coal blending method according to claim 1 or 2, characterized in that: By mixing the ash residue of the gasifier into the raw coal of the gasifier, the ash characteristics of the obtained blended coal also meet the following requirement: the Fe2O3 content in the ash is ≤ 18 wt%, preferably 8 - 18 wt%.

4. The coal blending method according to any one of claims 1 to 3, characterized in that: The blended coal is used in an entrained flow gasifier, and the entrained flow gasifier is a water coal slurry gasifier or a dry pulverized coal gasifier; Preferably, the water coal slurry gasifier is a hot fireplace.

5. The coal blending method according to claim 4, characterized in that: When the entrained flow gasifier is a water coal slurry gasifier, the ash flow temperature of the blended coal obtained by the mixing is 1100 - 1350 °C.

6. The coal blending method according to any one of claims 1 - 3, wherein The blended coal also has the following coal ash characteristics: T 25 <1300℃,T 2.5 >1300℃, and T 2.5 -T 25 ≥50℃; Or, T 25 <1400℃,T 2.5 >1400℃, and T 2.5 -T 25 ≥50℃; Wherein T 25 is the temperature corresponding to the viscosity of 25 Pa·s after the coal ash mixed with coal forms liquid slag, T 2.5 It is the temperature corresponding to the viscosity of 2.5 Pa·s after the coal ash of the blended coal forms liquid slag.

7. The coal blending method according to any one of claims 1 to 3, characterized in that: The raw coal that does not meet the requirements for coal used in entrained flow gasification refers to the raw coal having at least one of the following characteristics: a) The ash flow temperature of the ash is lower than 1100 °C; b) The raw coal with an ash flow temperature higher than 1350 °C for entrained flow water coal slurry gasification or the raw coal with an ash flow temperature higher than 1450 °C for entrained flow dry pulverized coal gasification; c) The Fe2O3 content in the ash is higher than 18 wt%; d) The ash content is lower than 6 wt%; e)T 25 ≥1400℃; f)T 2.5 -T 25 <50℃; Among them, the T 25 is the temperature at which the viscosity of the coal ash of the raw coal is 25 Pa·s after forming liquid slag, T 2.5 It is the temperature corresponding to when the viscosity of the coal ash of the raw coal is 2.5 Pa·s after forming liquid slag.

8. The coal blending method according to any one of claims 1 to 3, characterized in that: The ash residue of the gasifier is selected from at least one of gasification fine slag and gasification coarse slag, and preferably includes at least gasification fine slag; Preferably, when performing the mixing, the gasification fine slag is preferentially mixed into the raw coal of the gasifier. When the blended coal obtained after mixing cannot meet the requirements for the ash characteristics of the blended coal, the gasification coarse slag is mixed into the raw coal of the gasifier; Preferably, when the ash flow temperature of the raw coal of the gasifier is higher than 1350 °C, at least one ash residue of the gasifier that satisfies W(CaO) / W(Fe2O3) > 1.0 is used for the mixing; wherein, W(CaO) and W(Fe2O3) are the mass percentages of CaO and Fe2O3 in the ash composition of the ash residue of the gasifier, respectively.

9. A blended coal for an entrained flow gasifier, characterized in that: Obtained by blending using the coal blending method according to any one of claims 1 - 8.

10. A use of gasifier ash, characterized in that: Using gasifier ash to mix with gasifier raw coal to obtain blended coal suitable for entrained flow gasification, wherein the gasifier raw coal refers to raw coal that does not meet the requirements for coal for entrained flow gasification; Preferably, the gasifier ash is blended with the gasifier raw coal using the coal blending method described in any one of claims 1 to 8 to obtain the blended coal suitable for entrained flow gasification.

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