Coal blending and coal blending method for entrained flow coal gasification

Abstract

The present application relates to the technical field of coal gasification, in particular to a coal blending for entrained-flow bed coal gasification and a coal blending method, the coal blending is obtained by blending at least two base coals, and the ash content of the coal blending satisfies: 5wt% < A d <20wt%, and a < 18wt%, 1

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coal gasification, in particular to coal blending and a coal blending method for entrained-flow-bed coal gasification. BACKGROUND

[0002] Coal gasification refers to a process in which solid fuels such as coal or coke, semi-coke, etc. are reacted with a gasifying agent under high-temperature normal pressure or pressurized conditions to be converted into gaseous products and a small amount of residual slag. An entrained-flow-bed gasification furnace is one of the industrial furnaces used in coal gasification technology. Coal quality is crucial to the long-period stable operation of the entrained-flow-bed gasification furnace, and in general, each type of entrained-flow-bed gasification technology needs to solve its coal adaptability through coal blending. Therefore, coal adaptability is the key to ensuring the long-period stable operation of the gasification furnace, and coal blending is an important means to solve this problem.

[0003] CN105542820A discloses a coal blending method for a gasification furnace, which comprises the step of blending at least two types of coal to obtain gasification furnace coal, the flow temperature of the ash of the at least two types of coal used for blending is greater than 1300℃, and the R value of the ash of the obtained gasification furnace coal is calculated by detection; the amount of the at least two types of coal used for blending is such that the R value of the ash of the obtained gasification furnace coal is 150-220; the purpose of this method is limited to solving coal with a high ash fusion point, i.e. the flow temperature of the ash of the at least two types of coal is required to be greater than 1300℃, and the coal types used for blending are relatively single, and the coal blending method is not universal.

[0004] CN102676226A 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, so that the ash content of the mixture is lower than 21.08%, and the mixed coal can increase the effective gas amount per ton of standard coal in Shell pulverized coal gasification; however, this method is mainly aimed at Shell pulverized coal pressurized gasification technology, and specific requirements are proposed for the gasification raw materials, i.e. coal with an ash content higher than 21.08% and petroleum coke, and it is not universal.

[0005] CN101845330A discloses a coal blending method suitable for Texaco coal water slurry pressurized gasification, which is to blend raw materials with an ash fusion temperature >1500℃ and an ash fusion temperature <1300℃ to uniformly blend into Texaco coal water slurry gasification coal; this coal blending method is mainly aimed at Texaco coal water slurry pressurized gasification technology, and specific requirements are proposed for the gasification raw materials, and it is not universal.

[0006] In summary, most of the existing coal blending methods are only developed for a certain specific gasification technology, and the coal blending process is not subject to specific coal blending rules, and it is impossible to determine whether it is reliable, and it is not universal. SUMMARY

[0007] The purpose of the present invention is to overcome the problem that the existing coal blending method in the prior art is only targeted at a certain gasification technology and is not universal, and to provide coal blending and coal blending method for entrained flow coal gasification.

[0008] In order to achieve the above object, the first aspect of the present invention provides a coal blend for entrained flow coal gasification, wherein the coal blend is obtained by blending at least two base coals, and the ash content of the coal blend satisfies: 5wt% d <20wt%, and a<18wt%, 1

[0009] Among them, a is the weight content of Fe2O3 in the ash of the blended coal; b is the weight content of SiO2 in the ash of the blended coal; c is the weight content of Al2O3 in the ash of the blended coal; d is the weight content of CaO in the ash of the blended coal.

[0010] A second aspect of the present invention provides a method for coal blending, wherein the method comprises:

[0011] S1. Setting the ratio of at least two base coals, and performing linear summation calculation on the property parameters of at least two base coals under the same reference conditions to obtain the property parameters of the blended coal;

[0012] S2. Determine whether the property parameters of the coal blending meet the constraint conditions;

[0013] S3. When the coal blending satisfies the constraint conditions, conduct coal blending economic analysis to optimize the ratio of the two base coals;

[0014] The constraints include: the ash content of the coal blending meets the following requirements: 5wt% d <20wt%, and a<18wt%, 1

[0015] a is the weight content of Fe2O3 in the ash of the blended coal; b is the weight content of SiO2 in the ash of the blended coal; c is the weight content of Al2O3 in the ash of the blended coal; d is the weight content of CaO in the ash of the blended coal.

[0016] Through the above technical solution, the present invention constrains the property parameters of the coal blend within a specific range, so that the coal blend can be used in an entrained flow gasifier, which has significant practical significance for ensuring the stable, efficient and economical operation of the entrained flow gasifier.

[0017] The coal blending method provided by the present invention has no special restrictions on the type of base coal and can be used to determine whether the blended coal obtained by blending multiple types of coal meets the requirements of an entrained flow gasifier, and has universal applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] ​​​​Figure 1 is a flow chart of a coal blending method according to one embodiment of the present invention;

[0019] Figure 2 1 is an operating status diagram of the coal blend in the gasifier according to Example 1 of the present invention; wherein, a is the temperature change curve of the gasifier; b is the change curve of the crude synthesis gas output in the gasifier; c is the change curve of the effective synthesis gas content in the gasifier; d is the change curve of the coal slurry flow rate; and e is the production curve of the effective gas in the gasifier. DETAILED DESCRIPTION

[0020] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0021] As mentioned above, the first aspect of the present invention provides a blended coal for entrained flow coal gasification, wherein the blended coal is obtained by blending at least two base coals, and the ash content of the blended coal satisfies: 5wt% d <20wt%, and a<18wt%, 1 d is the dry basis ash of the blended coal, a is the weight content of Fe2O3 in the ash of the blended coal; b is the weight content of SiO2 in the ash of the blended coal; c is the weight content of Al2O3 in the ash of the blended coal; d is the weight content of CaO in the ash of the blended coal.

[0022] The inventors of the present invention have discovered that when the ash content of the blended coal meets the above requirements, the blended coal can be used as coal for entrained flow gasification. The method of the present invention is applicable to raw coal of any type, and has no specific requirements on the flow temperature, melting temperature, ash content, etc. of the coal.

[0023] In order to make the gasifier operate efficiently and stably, under preferred conditions, the ash melting point of the blended coal also meets the following conditions: the flow temperature FT of the ash of the blended coal is less than 1400°C, preferably, the flow temperature FT of the ash of the blended coal is less than 1300°C.

[0024] The inventors of the present invention also found that the flow temperature requirements of the ash of the blended coal in the water-coal slurry gasification process and the dry coal powder gasification process are different. For the water-coal slurry gasification process, the flow temperature of the ash of the blended coal needs to be less than 1300°C; but for the dry coal powder gasification process, the flow temperature of the ash of the blended coal only needs to be less than 1400°C.

[0025] ​​According to the present invention, under preferred conditions, the ash melting point of the coal blend also meets the following conditions: the difference between the flow temperature FT and the deformation temperature DT of the coal blend is not less than 50°C, for example, it can be 50°C, 60°C, 70°C, or 80°C; preferably, the difference between the flow temperature FT and the deformation temperature DT of the coal blend is 100-200°C.

[0026] The "ash melting point" of ash is well known to those skilled in the art. It is not a specific temperature point value, but a temperature range. It refers to the temperature characteristics of ash when it softens, melts, and flows under high temperature conditions. It is an important indicator of coal for power generation and gasification, including deformation temperature, softening temperature, hemisphere temperature and flow temperature.

[0027] According to the present invention, under preferred conditions, T 2.5 -T 25 ≥50℃, where T 25 T is the temperature value corresponding to the viscosity of the ash in the molten state of the coal is 25Pa·s; 2.5 The temperature value corresponding to the viscosity of the ash of the blended coal in the molten state is 2.5 Pa·s; preferably, T 2.5 With T 25 The difference is 100-200℃.

[0028] In the present invention, the blended coal is obtained by combining at least two base coals, that is, there are at least two base coals, and it can also be three, four or more. The number of base coals can be adjusted accordingly according to actual needs, and the present invention does not make any special limitations.

[0029] Figure 1 is a flow chart of a coal blending method according to one embodiment of the present invention, as shown in FIG. Figure 1 As shown, the second aspect of the present invention provides a method for coal blending, the method comprising:

[0030] S1. Setting the ratio of at least two base coals, and performing linear summation calculation on the property parameters of at least two base coals under the same reference conditions to obtain the property parameters of the blended coal;

[0031] S2. Determine whether the property parameters of the coal blending meet the constraint conditions;

[0032] S3. When the coal blending satisfies the constraint conditions, conduct coal blending economic analysis to optimize the ratio of the two base coals;

[0033] The constraints include: the ash content of the coal blending meets the following requirements: 5wt% d <20wt%, and a<18wt%, 1 d ​​a is the weight content of Fe2O3 in the ash of the coal blend; b is the weight content of SiO2 in the ash of the coal blend; c is the weight content of Al2O3 in the ash of the coal blend; and d is the weight content of CaO in the ash of the coal blend.

[0034] The property parameters under the same reference condition refer to property parameters obtained under the same test method, and in the present application, the property parameters are the flow temperature FT of the ash of the coal blend, the deformation temperature DT of the ash of the coal blend, and the temperature value T 25 and T 2.5 is the temperature value corresponding to the viscosity of 2.5 Pa·s of the ash of the coal blend in a molten state. 2.5

[0035] According to the present application, under the preferred conditions, the constraint condition further comprises: the flow temperature FT of the ash of the coal blend is less than 1400℃, preferably less than 1300℃.

[0036] According to the present application, under the preferred conditions, the constraint condition further comprises: the difference between the flow temperature FT and the deformation temperature DT of the coal blend is not less than 50℃, for example, it can be 50℃, 60℃, 70℃, 80℃, 100℃, 150℃ or 200℃, preferably 100-200℃.

[0037] According to the present application, under the preferred conditions, the constraint condition further comprises: T 2.5 -T 25 ≥ 50℃; wherein T 25 is the temperature value corresponding to the viscosity of 25 Pa·s of the ash of the coal blend in a molten state; and T 2.5 is the temperature value corresponding to the viscosity of 2.5 Pa·s of the ash of the coal blend in a molten state.

[0038] According to the present application, under the preferred conditions, the economic analysis of the coal blend comprises: adjusting the proportion of each base coal according to the price and transportation cost of each base coal under the condition of meeting the constraint condition.

[0039] The method for blending coal provided by the present application can determine whether the coal blend is suitable for the entrained-flow gasification furnace according to the constraint condition, and adjust the proportion of the coal type base coal through the economic analysis of the coal blend, so as to reduce the cost of the coal for gasification, which has a significant practical significance for ensuring the stable, efficient and economic operation of the entrained-flow gasification furnace.

[0040] The present application will be described in detail below through examples.

[0041] In the following examples, the flow temperature FT and the deformation temperature DT of the ash are obtained by ash melting point tester; the temperature value T​25 And the temperature value T corresponding to the viscosity of the ash of the blended coal in the molten state is 2.5Pa·s 2.5 The test was carried out according to the electric power industry standard DL / T660-2007 (test method for high temperature viscosity characteristics of ash).

[0042] In the following examples, the types of base coals and their industrial and elemental analyses are shown in Table 1.

[0043] The following examples adopt Figure 1 Coal blending is carried out using the coal blending method shown.

[0044] Table 1

[0045]

[0046] Example 1

[0047] S1. According to the property parameters of the two base coals (coal sample 1 and coal sample 2) in Table 1, the weight content of coal sample 1 is set to 50wt% and the weight content of coal sample 2 is set to 50wt%, that is, the two base coals are mixed in a ratio of 1:1 to obtain coal blend 1, and the property parameters of the two base coals are linearly added to obtain the property parameters of coal blend 1, as shown in Table 2;

[0048] Table 2

[0049]

[0050]

[0051] S2. Determine whether the property parameters of coal blend 1 meet the constraint conditions;

[0052] After calculation, the dry basis ash content of coal blend 1 is A d =9.63wt% (<20wt%), a=15.69wt% (<18wt%), 1

[0053] a is the weight content of Fe2O3 in the ash of coal blend 1; b is the weight content of SiO2 in the ash of coal blend 1; c is the weight content of Al2O3 in the ash of coal blend 1; d is the weight content of CaO in the ash of coal blend 1;

[0054] The ash flow temperature after coal blending was measured by an ash melting point instrument to be FT = 1178°C and the deformation temperature DT = 1091°C, which met the requirements of FT < 1300°C (water-coal slurry gasification) and FT < 1400°C (dry coal powder gasification) and FT-DT = 87°C > 50°C, and was judged to meet the conditions;

[0055] ​Test results of ash viscosity-temperature characteristics of coal blend 1: T 2.5 =1297.7℃, T 25 =1164.7℃, T 2.5 -T 25 =133℃≥50℃, the judgment also meets the conditions;

[0056] It was determined that the property parameters of the coal blend 1 obtained under this blending ratio all met the gasification constraints and were suitable for use in entrained flow gasification.

[0057] S3. Adjustment and optimization of coal blending ratio

[0058] Taking into account the fluctuations in coal prices and transportation costs, this example assumes that the price of coal sample 2 is 500 yuan / ton, the transportation distance is 500 kilometers, the price of coal sample 1 is 600 yuan / ton, the transportation distance is 1000 kilometers, and the transportation price is calculated at 0.35 yuan / ton·km. In addition, the coal blending ratio of coal sample 2 is α, and the coal blending ratio of coal sample 1 is β, β = 1-α. Then the cost price C per ton of blended coal is:

[0059] C=α×(500+0.35×500)+β×(600+1000×0.35)

[0060] Then C = 950 - 275 × α

[0061] The above formula shows that the higher the coal blending ratio of coal sample 2, the lower the cost per ton of coal. Therefore, the coal blending ratio was readjusted and analyzed and judged. The results are shown in Tables 3 and 4:

[0062] Table 3

[0063]

[0064] In Table 3, coal blend 2 is a coal blend composed of coal sample 2 and coal sample 1 at a weight ratio of 7:3; coal blend 3 is a coal blend composed of coal sample 2 and coal sample 1 at a weight ratio of 4:1.

[0065] Table 4

[0066]

[0067] In Table 4, coal blend 2 is a coal blend composed of coal sample 2 and coal sample 1 at a weight ratio of 7:3; coal blend 3 is a coal blend composed of coal sample 2 and coal sample 1 at a weight ratio of 4:1.

[0068] From the data in Table 3 and Table 4, we can judge that the T 2.5 -T 25 =44.4℃<50℃; does not meet the gasification constraint conditions and is not suitable for coal used in entrained flow gasification.

[0069] All property parameters of coal blend 2 meet the above constraints and are therefore suitable for use in entrained flow gasification.

[0070] From the above analysis, it can be concluded that coal blending 2 (when the weight ratio of coal sample 2 to coal sample 1 is 7:3) can meet the coal requirements for entrained flow gasification and can also reduce the cost of coal blending.

[0071] The results of the operation of coal blend 2 in the gasifier are as follows: Figure 2 As shown, from Figure 2 It can be seen that the temperature of the gasifier, the output of crude synthesis gas, the content of effective synthesis gas, the coal slurry flow rate and the output of effective gas are all in a stable state without large fluctuations; that is, coal blend 2 can operate stably in the gasifier for a long time, and the effective gas content is about 80%.

[0072] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for coal blending, characterized in that: The method comprises: S1. Setting the ratio of at least two base coals, and performing linear summation calculation on the property parameters of at least two base coals under the same reference conditions to obtain the property parameters of the blended coal; S2. Determine whether the property parameters of the coal blending meet the constraint conditions; S3. When the coal blending satisfies the constraint conditions, conduct coal blending economic analysis to optimize the ratio of the two base coals; Among them, the constraint condition is: the ash content of the coal blending meets: 5wt% d <20wt%, and a<18%, 1 2.5 -T 25 ≥50℃;​​ a is the weight content of Fe2O3 in the ash of the blended coal; b is the weight content of SiO2 in the ash of the blended coal; c is the weight content of Al2O3 in the ash of the blended coal; d is the weight content of CaO in the ash of the blended coal; T 25 The temperature corresponding to the viscosity of the ash in the molten state of the coal is 25 Pa·s; T 2.5 The temperature value corresponding to the viscosity of the ash in the molten state is 2.5 Pa·s.

2. The method according to claim 1, wherein The flow temperature FT of the ash of the blended coal is less than 1300°C.

3. The method according to claim 1 or 2, wherein: The coal blending economic analysis includes: adjusting the proportion of each base coal or changing the type of coal according to the price and transportation cost of each base coal when the constraint conditions are met.

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