Method for selecting coal quality of coal for coal water slurry gasification

Abstract

The invention belongs to the technical field of coal water slurry gasification, and relates to a coal quality selection method for coal for coal water slurry gasification, which comprises the following steps: S1, acquiring coal quality analysis data of different coal types: internal water, ash content, alkali-acid ratio, silica-alumina ratio and flowing temperature of each coal type; s2, constructing a relationship between the coal quality analysis data of each coal type and the mixed coal internal water, the mixed coal ash content, the mixed coal ash melting point, the mixed coal alkali-acid ratio and the mixed coal silica-alumina ratio of the mixed coal; S3, substituting the coal quality analysis data in the step S1 into the formula in the step S2 respectively, and calculating the mass part ratio of different coal types according to the target requirements of the mixed coal fed into the gasification furnace on water in the mixed coal, the mixed coal ash content, the mixed coal ash melting point, the mixed coal alkali-acid ratio and the mixed coal silica-alumina ratio. The mixing ratio of different coal types is accurately controlled, so that the gasification efficiency is improved, and the production stability is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of water-coal slurry gasification and relates to a method for selecting coal quality for water-coal slurry gasification. Background Art

[0002] The water-coal slurry gasification process has the advantages of easy control of feed and high single-furnace output. This technology can effectively guarantee my country's energy conversion and clean production, and is the basic process technology for producing raw materials such as methanol and ethylene glycol. Water-coal slurry gasification uses high-pressure pure oxygen (purity above 99.6%) and water-coal slurry with a concentration of about 58% (wt) as raw materials, adopts an entrained bed reactor, and sprays into the gasifier through four process burners on the same horizontal plane. Partial oxidation reaction is carried out under pressurized non-catalytic conditions to generate raw water gas with CO and H2 as effective components.

[0003] The operation of water-coal slurry gasification equipment basically relies on coal. In recent years, due to the state's control over energy, the supply of coal is in short supply, and a "coal shortage" phenomenon has occurred. This has caused many water-coal slurry gasification equipment to use coal quality that deviates from the designed coal quality and is unstable. The slurry formation of the ground water-coal slurry is poor, and the concentration and viscosity indicators are abnormal. The adjustment of additives cannot meet the coal slurry quality requirements, and the gasifier wall temperature is abnormal, the gasifier slag is sticky, the furnace temperature fluctuates slightly, the slag is abnormal (lump slag appears), the water system contains slag, the pH value of the ash water drops seriously, the flash system pipeline equipment leaks, and the equipment operation cycle is short, which brings great difficulties to the process operation and affects the safe and stable operation of the system.

[0004] In order to adapt to the continuous changes in the coal market, the raw materials of the gasifier are generally a combination of different types of coal and blending. For example, when different types of coal are mixed and blended, the proportion of different types of coal is difficult to control due to the different coal qualities, which seriously affects the combustion effect of the coal, reduces the gasification efficiency, and deteriorates the production stability. Summary of the invention

[0005] In order to solve the technical problem in the above background technology that the mixing ratio of different coal types is difficult to control, which seriously affects the combustion effect of coal, reduces gasification efficiency and deteriorates production stability, the present invention provides a method for selecting coal quality for water-coal slurry gasification.

[0006] The present invention accurately controls the blending ratio of different coal types according to the coal quality, thereby improving the gasification efficiency and ensuring production stability.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A method for selecting coal quality for water-coal slurry gasification comprises the following steps:

[0009] S1. Obtain coal quality analysis data for different types of coal

[0010] The coal quality analysis data of different types of coal include: internal water, ash content, alkali-acid ratio, silicon-aluminum ratio and flow temperature; the alkali-acid ratio is the ratio of the content of alkaline components to the content of acidic components; the silicon-aluminum ratio is the ratio of the content of silicon components to the content of aluminum components;

[0011] S2. Construct the relationship between the coal quality analysis data of different types of coal and the water content of mixed coal, mixed coal ash content, mixed coal ash melting point, mixed coal alkali-acid ratio and mixed coal silicon-aluminum ratio of mixed coal, as follows:

[0012] Water in mixed coal:

[0013] Mixed coal ash content:

[0014] Mixed coal ash melting point:

[0015] Alkali-acid ratio of mixed coal:

[0016] Silicon-aluminum ratio of mixed coal:

[0017] Wherein: n is the number of coal types; N1, N2, N3..., Nn are the mass parts of each coal type, M1, M2, M3..., Mn are the internal water content of each coal type; Ad1, Ad2, Ad3..., Adn are the ash content of each coal type; T1, T2, T3..., Tn are the flow temperature of each coal type; are the alkali-acid ratios of each type of coal; are the silicon-aluminum ratio of each type of coal; B1, B2, B3, ..., Bn are the total content of alkaline components in each type of coal; A1, A2, A3, ..., An are the total content of acidic components in each type of coal; S1, S2, S3, ..., Sn are the silicon content in each type of coal; Al1, Al2, Al3, ..., Aln are the aluminum content in each type of coal;

[0018] S3. Substitute the coal quality analysis data of different types of coal obtained in step S1 into the formula of step S2 respectively, and calculate N1:N2:N3:...:Nn according to the target requirements of the mixed coal entering the gasifier for the water content in the mixed coal, the ash content in the mixed coal, the melting point of the mixed coal, the alkali-acid ratio in the mixed coal and the silicon-aluminum ratio in the mixed coal.

[0019] It is further defined that in step S1, the alkaline components refer to: SiO2 and Al2O3; the acidic components refer to: Fe2O3, CaO, MgO, K2O and Na2O; the silicon component is measured as SiO2, and the aluminum component is measured as Al2O3.

[0020] It is further defined that in step S3, the target requirements for the mixed coal entering the gasifier with respect to the water content in the mixed coal, the ash content in the mixed coal, the melting point of the ash in the mixed coal, the alkali-acid ratio of the mixed coal and the silicon-aluminum ratio of the mixed coal are: the water content in the mixed coal is less than 8%, the ash content in the mixed coal is less than 10%, the ash melting point of the mixed coal is less than 1300°C, the silicon-aluminum ratio of the mixed coal is 2 to 3, and the alkali-acid ratio of the mixed coal is 0.3 to 0.8.

[0021] It is further defined that in step S1, different types of coal must also meet the following indicators: particle size ≤ 10 mm, residual carbon content in slag not higher than 1.5 wt%, volatile matter 25 wt% to 35 wt% and fixed carbon 45 wt% to 60 wt%.

[0022] It is further defined that in step S3, the slurry properties of the mixed coal fed into the gasifier meet the following requirements: coal slurry particle size ≤ 200 mesh, accounting for ≥ 50%, coal slurry concentration 60%, viscosity 500-1000mpa.s, and coal slurry water separation rate ≤ 4%.

[0023] It is further defined that in step S3, the viscosity-temperature characteristics of the coal ash of the mixed coal fed into the gasifier satisfy: the viscosity of the coal slurry is 3 to 25 Pa.s.

[0024] It is further defined that in step S3, the operating temperature of the mixed coal fed into the gasifier is 1100°C to 1400°C.

[0025] The beneficial effects of the technical solution of the present invention are:

[0026] 1. The present invention studies the blending ratio under different coal combinations to reduce the impact of coal quality changes on water-coal slurry gasification, provides an effective method for selecting coal quality, and improves gasification efficiency and production stability.

[0027] 2. The selection method provided by the present invention carries out mixed combustion according to different proportions, strictly controls the quality of coal entering the gasification furnace, meets the requirements of coal quality data indicators, optimizes the slurry formation of water-coal slurry, improves the stability and fluidity of water-coal slurry, realizes large-scale and stable production of water-coal slurry gasification process industry, and improves production operation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The viscosity-temperature characteristic curve of coal ash slag when the mass ratio of mixed coal is 1:1:1;

[0029] Figure 2 The viscosity-temperature characteristic curve of coal ash slag when the mass ratio of mixed coal is 3:5:2;

[0030] Figure 3 This is the viscosity-temperature characteristic curve of fly ash slag when the mass ratio of mixed coal is 4:4:2. DETAILED DESCRIPTION

[0031] The technical solution protected by the present invention is now described in detail in conjunction with the embodiments. However, it is obvious that the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. Based on the described embodiments of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present application.

[0032] The present invention provides a method for selecting coal quality for water-coal slurry gasification, which specifically comprises the following steps:

[0033] S1. Obtain coal quality analysis data for different types of coal

[0034] The coal quality analysis data of different coal types include: internal water, ash content, alkali-acid ratio, silicon-aluminum ratio and flow temperature of each coal type.

[0035] The alkali-acid ratio is the ratio of the content of the alkaline component to the content of the acidic component; the silicon-aluminum ratio is the ratio of the content of the silicon component to the content of the aluminum component.

[0036] Moisture is divided into external moisture (external water) and internal moisture (internal water). External water is the moisture attached to the surface of coal particles; internal water (Minh) is the moisture adsorbed in the pores inside the coal particles. Internal moisture needs to be at a temperature above 100°C for a certain period of time to evaporate.

[0037] Ash (Ad) refers to the residue left after the complete combustion of coal. It does not directly participate in the gasification reaction, but consumes the reaction heat generated by the coal in the oxidation reaction to be used for the heating, melting, and conversion of the ash.

[0038] In step S1 of the present invention, it is also necessary to limit the strength, slag carbon residue, volatile matter and fixed carbon of each type of coal.

[0039] Volatile matter is the sum of gaseous and liquid products produced by the decomposition of coal samples by heating. Coal with high volatile content is easy to ignite and burn during the gasification process, which is beneficial to the gasification of coal and the improvement of carbon conversion rate. However, coal with too high volatile content is easy to spontaneously combust, which brings inconvenience to the storage of coal.

[0040] Fixed carbon is the main combustible component in coal. The higher its content, the higher the calorific value of coal. Coal with high fixed carbon content can increase the yield of effective synthesis gas during gasification.

[0041] Preferably, different types of coal also need to meet the following indicators: particle size ≤ 10 mm, residual carbon content in slag not higher than 1.5 wt%, volatile matter 25 wt% to 35 wt% and fixed carbon 45 wt% to 60 wt%.

[0042] S2. Construct the relationship between the coal quality analysis data of different types of coal and the water content of mixed coal, mixed coal ash content, mixed coal ash melting point, mixed coal alkali-acid ratio and mixed coal silicon-aluminum ratio of mixed coal, as follows:

[0043] Water in mixed coal:

[0044] Mixed coal ash content:

[0045] Mixed coal ash melting point:

[0046] Alkali-acid ratio of mixed coal:

[0047] Silicon-aluminum ratio of mixed coal:

[0048] Wherein: n is the number of coal types; N1, N2, N3..., Nn are the mass parts of each coal type, M1, M2, M3..., Mn are the internal water content of each coal type; Ad1, Ad2, Ad3..., Adn are the ash content of each coal type; T1, T2, T3..., Tn are the flow temperature of each coal type; are the alkali-acid ratios of each type of coal; are the silicon-aluminum ratios of each type of coal; B1, B2, B3..., Bn are the total content of alkaline components in each type of coal; A1, A2, A3..., An are the total content of acidic components in each type of coal; S1, S2, S3,..., Sn are the silicon content in each type of coal; Al1, Al2, Al3,..., Aln are the aluminum content in each type of coal.

[0049] S3. Substitute the coal quality analysis data of different types of coal obtained in step S1 into the formula of step S2 respectively, and calculate N1:N2:N3:...:Nn according to the target requirements of the mixed coal entering the gasifier for the water content in the mixed coal, the ash content in the mixed coal, the melting point of the mixed coal, the alkali-acid ratio in the mixed coal and the silicon-aluminum ratio in the mixed coal.

[0050] Preferably, according to the technical indicators of the mixed coal entering the gasifier, the target requirements for water content in the mixed coal, ash content in the mixed coal, melting point of the mixed coal ash, alkali-acid ratio of the mixed coal and silicon-aluminum ratio of the mixed coal are: water content in the mixed coal <8%, ash content in the mixed coal <10%, ash melting point of the mixed coal <1300°C, silicon-aluminum ratio of the mixed coal is 2-3, and alkali-acid ratio of the mixed coal is 0.3-0.8.

[0051] In the present invention, the coal ash composition refers to the various chemical elements and compounds contained in the coal ash after the coal is burned or pyrolyzed. Acidic (A) ash includes SiO2, Al2O3, etc., and alkaline (B) ash includes Fe2O3, CaO, MgO, K2O and Na2O. A high acidic ash content in the coal ash will increase the ash melting point, while a high alkaline ash content will reduce the ash melting point. In order to stabilize a more reasonable ash melting point, the alkali-acid ratio (Si / Al) of the coal ash composition is controlled to be 0.3-0.8 to ensure the safe and stable operation of the equipment and efficient energy utilization.

[0052] Ash melting point (T): refers to the temperature at which coal ash begins to deform, soften, melt and flow when heated under certain conditions. Usually, deformation temperature (DT), softening temperature (ST), hemisphere temperature (HT) and flow temperature (FT) are used. In this embodiment, the gasifier operating temperature index is generally higher than the ash fusibility flow temperature (FT), so that the ash slag forms liquid flow slag. The ash melting point (flow temperature FT) is controlled to be less than 1300°C.

[0053] Silicon-aluminum ratio (Si / Al) is the ratio of the content of silicon to aluminum in a substance. A high silicon-aluminum ratio increases the softening temperature of the coal ash, and the flow temperature will also increase. The viscosity of the melt is large and the fluidity is poor. It is necessary to operate at a higher temperature to ensure that the coal ash has good fluidity and slag removal performance. At the same operating temperature, if the silicon-aluminum ratio is higher than 3, the fluidity of the gasifier ash slag is reduced, and the slag is easy to form block slag. The silicon-aluminum ratio should be controlled between 2 and 3.

[0054] According to the above requirements, the parameters of each type of coal are substituted into the five formulas, and the mass ratio is calculated. Then, different types of coal are blended according to the mass ratio, so that the slurryability, ash viscosity-temperature characteristics, operating temperature and ash fusibility and flow temperature of the mixed coal entering the gasifier meet the following indicators.

[0055] Slurryability refers to the ease with which coal can be made into water-coal slurry under specific conditions and the quality of the resulting water-coal slurry. Good coal slurryability means that the coal has high slurry concentration, low viscosity, good fluidity, and good stability in both dynamic and static states.

[0056] The viscosity-temperature characteristics of coal ash refer to the viscosity change characteristics of coal ash at different temperatures. If the viscosity is too high, it will cause difficulty in fluid flow, affect the slag discharge performance of the gasifier, and may even cause blockage; if the viscosity is too low, it may cause excessive erosion of the furnace wall refractory material and shorten the equipment life.

[0057] Preferably, the slurry properties of the mixed coal fed into the gasifier meet the following requirements: coal slurry particle size ≤ 200 mesh, accounting for ≥ 50%, coal slurry concentration 60%, viscosity 500-1000mpa.s, and coal slurry water separation rate ≤ 4%.

[0058] Preferably, the viscosity-temperature characteristics of the coal ash of the mixed coal fed into the gasifier satisfy the following requirements: the viscosity of the coal slurry is 3-25 Pa.s.

[0059] Preferably, the operating temperature of the mixed coal fed into the gasifier is 1100°C to 1400°C.

[0060] In the present invention, the water content of the mixed coal is less than 8%, the ash content is less than 10%, the ash melting point is less than 1300°C, the coal ash silicon-aluminum ratio is controlled at 2-3, and the alkali-acid ratio is controlled at 0.3-0.8. When each index reaches the target requirements, the mixed coal quality has good slurrying property, can also improve the viscosity-temperature characteristics of the coal ash, and the operating temperature and ash fusibility flow temperature meet the requirements of the gasifier, thereby improving the stability of the gasifier.

[0061] The above method of the present invention is described in detail below with reference to specific embodiments.

[0062] Example 1

[0063] This embodiment takes the mixed selection of three types of coal as an example to illustrate the method for selecting coal quality for water-coal slurry gasification, which specifically includes the following steps:

[0064] S1. Obtain coal quality analysis data for different types of coal

[0065] The coal quality analysis data of different coal types include: internal water, ash content, alkali-acid ratio, silicon-aluminum ratio and flow temperature of each coal type.

[0066] In this embodiment, the three coals are recorded as coal type 1, coal type 2 and coal type 3 respectively, and the coal quality analysis data can be found in Table 1 and Table 2.

[0067] Table 1 Coal composition analysis of each coal type

[0068] Element Design coal Coal Type 1 Coal Type 2 Coal Type 3 Internal water M (Wt%) ＜8 7.39 2.64 7.6 Gray Ad (Wt%) ＜10 6.07 12.68 5.15 V(Wt%) 29.9 30.76 33.04 33.18 Solid FC (Wt%) 53.99 55.79 49.35 54.08

[0069] According to the mixed coal selection standards, the volatile matter and fixed carbon of the three types of coal meet the index requirements for coal entering the gasifier.

[0070] Table 2 Analysis of coal ash composition for each type of coal

[0071]

[0072] In the table: alkali-acid ratio refers to: the ratio of the content of alkaline components to the content of acidic components in coal ash; specifically, the alkaline components refer to: SiO2 and Al2O3; the acidic components refer to: Fe2O3, CaO, MgO, K2O and Na2O.

[0073] Note: All the numbers in Table 2 are in mass fractions.

[0074] The silicon-aluminum ratio refers to the ratio of the silicon content to the aluminum content in coal ash; the silicon component is calculated as SiO2 and the aluminum component is calculated as Al2O3.

[0075] Ash fusibility analysis was conducted on the three types of coal, see Table 3.

[0076] Table 3 Ash fusibility analysis of each coal type

[0077] Coal water slurry gasification Coal Type 1 Coal Type 2 Coal Type 3 Deformation temperature DT℃ 1150 1150 1120 1123 Softening temperature ST℃ 1180 1170 1150 1142 Hemisphere temperature HT℃ 1220 1180 1160 1151 Flow temperature FT℃ 1250 1260 1170 1161

[0078] S2. Construct the relationship between the coal quality analysis data of different types of coal and the water content of mixed coal, mixed coal ash content, mixed coal ash melting point, mixed coal alkali-acid ratio and mixed coal silicon-aluminum ratio of mixed coal, as follows:

[0079] Water in mixed coal:

[0080] Mixed coal ash content:

[0081] Mixed coal ash melting point:

[0082] Alkali-acid ratio of mixed coal:

[0083] Silicon-aluminum ratio of mixed coal:

[0084] Where: n is the number of coal types; N1, N2, N3..., Nn are the mass parts of each coal type, M1, M2, M3..., Mn are the internal water content of each coal type; Ad1, Ad2, Ad3..., Adn are the ash content of each coal type; T1, T2, T3..., Tn are the flow temperatures of each coal type; are the alkali-acid ratios of each type of coal; are the silicon-aluminum ratios of each type of coal; B1, B2, B3..., Bn are the total content of alkaline components in each type of coal; A1, A2, A3..., An are the total content of acidic components in each type of coal; S1, S2, S3,..., Sn are the silicon content in each type of coal; Al1, Al2, Al3,..., Aln are the aluminum content in each type of coal.

[0085] S3. Substitute the coal quality analysis data of different coal types obtained in step S1 into the above relationship, and calculate the mass ratio of coal type 1: coal type 2: coal type 3 according to the coal requirement of the gasifier.

[0086] According to the coal requirements of the gasifier, the water content of the mixed coal is set to be less than 8%, the ash content is less than 10%, the ash melting point is less than 1300°C, the coal ash silicon-aluminum ratio is controlled at 2-3, and the alkali-acid ratio is 0.3-0.8.

[0087] Substituting the data in Table 1 and Table 2 into five equations:

[0088] Water in mixed coal:

[0089] Mixed coal ash content:

[0090] Mixed coal ash melting point:

[0091] Alkali-acid ratio of mixed coal:

[0092] Silicon-aluminum ratio of mixed coal:

[0093]

[0094] Taking the above five equations into consideration, the mass ratio of coal type 1: coal type 2: coal type 3 is finally determined to be (3~4): (3~5): (2~3).

[0095] In this embodiment, three types of coal are blended according to the mass ratio range calculated above, and the performance of the blended coal meets the requirements for coal used in water-coal slurry gasification.

[0096] The rationality of the mass ratio of the three types of coal determined by the above selection method of the present invention is further verified.

[0097] 1. For the three types of coal, select the following three mass proportions.

[0098] The first type of mixed coal: the mass ratio of coal quality 1: coal quality 2: coal quality 3 is 1:1:1.

[0099] The second type of mixed coal: the mass ratio of coal quality 1: coal quality 2: coal quality 3 is 3:5:2.

[0100] The third type of mixed coal: the mass ratio of coal quality 1: coal quality 2: coal quality 3 is 4:4:2.

[0101] 3. Analysis of technical objectives of coal blending

[0102] (1) According to the above mass ratio, the data in Table 1 are substituted into the calculation formula of water content in mixed coal, and the water content in mixed coal of the three mixed coals is calculated respectively.

[0103] Water in mixed coal:

[0104] Water content of the first mixed coal = (1×7.39+1×2.64+1×7.6) / (1+1+1) = 5.88 wt%

[0105] Water content of the second mixed coal = (3×7.39+5×2.64+2×7.6) / (3+5+2) = 5.057wt%

[0106] The water content of the third mixed coal = (4×7.39+4×2.64+2×7.6) / (4+4+2) = 5.532wt%

[0107] (2) According to the above mass ratio, the data in Table 1 are substituted into the calculation formula of the mixed coal ash content, and the mixed coal ash content of the three mixed coals is calculated respectively.

[0108]

[0109] Ash content of the first mixed coal = (1×6.07+1×12.68+1×5.15) / (1+1+1) = 7.97 wt%

[0110] Ash content of the second mixed coal = (3×6.07+5×12.68+2×5.15) / (3+5+2) = 9.19 wt%

[0111] Ash content of the third mixed coal = (4×6.07+4×12.68+2×5.15) / (4+4+2) = 8.53wt%

[0112] (3) According to the above mass ratio, the data of flow temperature FT in Table 3 are substituted into the calculation formula of the mixed coal ash melting point, and the mixed coal ash melting points of the three mixed coals are calculated respectively.

[0113] Mixed coal ash melting point: The melting point of the mixed ash of the first mixed coal = (1×1260+1×1170+1×1161) / (1+1+1) = 1197°C The melting point of the mixed ash of the second mixed coal = (3×1260+5×1170+2×1161) / (3+5+2) = 1195.2°C The melting point of the mixed ash of the third mixed coal = (4×1260+4×1170+2×1161) / (4+4+2) = 1204.2°C

[0114] (4) According to the above mass ratio, the data in Table 1 are substituted into the calculation formula of the alkali-acid ratio of the mixed coal, and the acid-alkali ratios of the three mixed coals are calculated respectively.

[0115]

[0116] The alkali-acid ratio of the first mixed coal is B / A = (1×0.43+1×0.49+1×0.45) / (1+1+1) = 0.457

[0117] The alkali-acid ratio of the second mixed coal is B / A = (3×0.43+5×0.49+2×0.45) / (3+5+2) = 0.464

[0118] The alkali-acid ratio of the third mixed coal is B / A = (4×0.43+4×0.49+2×0.45) / (4+4+2) = 0.458

[0119] (5) According to the above mass ratio, the data in Table 1 are substituted into the calculation formula of the silicon-aluminum ratio of the mixed coal, and the silicon-aluminum ratios of the three mixed coals are calculated respectively.

[0120]

[0121] The first mixed coal has a silicon-aluminum ratio Si / Al = (1×2.18+1×3.07+1×3.08) / (1+1+1) = 2.78

[0122] The silicon-aluminum ratio of the second mixed coal is Si / Al = (3×2.18+5×3.07+2×3.08) / (1+1+1) = 2.81

[0123] The silicon-aluminum ratio of the third mixed coal is Si / Al = (4×2.18+4×3.07+2×3.08) / (1+1+1) = 2.72

[0124] The five indicators of the mixed coal formed by mixing the different mass ratios calculated above: water content in the mixed coal, ash content, ash melting point, ash silicon-aluminum ratio and alkali-acid ratio are compared with the coal requirements of the gasifier.

[0125] The coal requirements for the gasifier are: water content in the mixed coal is less than 8%, ash content in the mixed coal is less than 10%, melting point of the mixed coal ash is less than 1300℃, silicon-aluminum ratio of the mixed coal is 2-3, and alkali-acid ratio of the mixed coal is 0.3-0.8.

[0126] It can be seen that the water content of the three mixed coals formed by mixing three different mass parts is 5.88wt%, 5.257wt% and 5.532wt%; the ash content of the mixed coal is 7.97wt%, 9.19wt% and 8.53wt%; the alkali-acid ratio of the mixed coal is 0.457, 0.464 and 0.458, and the silicon-aluminum ratio of the mixed coal is 2.78, 2.81 and 2.72 respectively; it can be seen that the water content of the mixed coal is less than 8%, the ash content of the mixed coal is less than 10%, the silicon-aluminum ratio of the mixed coal is within 2-3, and the alkali-acid ratio of the mixed coal is within 0.3-0.8. After the three mixed coals are mixed, the melting point of the mixed coal ash is less than 1300℃. It can be seen that the performance of the mixed coal formed by mixing the three types of coal according to the above mass ratio meets the requirements of coal for gasification furnace.

[0127] 4. Actual performance analysis of mixed coal

[0128] The three types of coal are mixed according to the three mass proportions of the three types of coal mentioned above, and then mixed coal is obtained. Various indicators of the mixed coal are tested to judge whether the performance of the mixed coal meets the coal quality requirements for the gasification furnace; at the same time, the actual test value is compared with the calculated value obtained by the above formula.

[0129] (1) Pulping analysis data

[0130] The slurry analysis was carried out on three mixed coal ratios that met the ash content requirements, according to the particle size distribution requirements of coal slurry produced by the coal mill.

[0131] Table 4 Coal slurry particle size distribution requirements

[0132] Mesh >16 mesh 40～80 80～200 200～325 <325 Coal slurry particle size ratio % 3.32 12.08 25.66 6.64 45.36

[0133] Through the above analysis, after coal is mixed according to the mass ratio calculated by the present invention, the gradation of the water-coal slurry meets the requirements.

[0134] (2) Coal slurry fluidity

[0135] Coal slurry fluidity quantitative test: the time required for 100 ml of coal slurry to flow out of the funnel. Fluidity classification (visual inspection): Grade A is a thin fluid, which flows continuously and smoothly without interruption; Grade B is a thick fluid, which flows relatively continuously and the fluid surface is not smooth; Grade C can only flow well with the help of external force; Grade D is muddy and cannot flow.

[0136] Table 5 Coal slurry fluidity analysis results

[0137]

[0138] It can be seen from the data table that the fluidity of the coal slurry ground from the three types of mixed coal is Class B or above, which meets the slurry formation requirements of the coal slurry.

[0139] (3) Fusibility and ash testing of mixed coal

[0140] The internal water content, ash content, ash solubility and ash content of three mixed coals with different mass fractions were tested and analyzed.

[0141] Table 6 Actual test values ​​of water content, ash content and coal ash solubility in mixed coal

[0142]

[0143] Table 7 Detection values ​​of coal ash of mixed coal

[0144]

[0145] From the test data of the three kinds of mixed coal in Table 6 and Table 7, it can be seen that the actual test values ​​of water in the mixed coal are 6.16wt%, 5.09wt%, and 5.85wt%, respectively, which meets the requirement that the water content of the mixed coal entering the gasifier is less than 8%. The actual test values ​​of the ash content of the mixed coal are 7.74wt%, 9.87wt%, and 8.8wt%, respectively, which meets the requirement that the ash content of the mixed coal entering the gasifier is less than 10%. The actual test values ​​of the ash melting point (FT) of the mixed coal are 1181℃, 1191℃, and 1199℃, respectively, which are higher than the operating temperature of 50-100℃ of ash fusibility flow temperature, and meet the requirement that the ash melting point of the mixed coal entering the gasifier is less than 1300℃. The actual test values ​​of the alkali-acid ratio of the mixed coal are 0.43, 0.37, and 0.59, respectively, which meets the alkali-acid ratio of the mixed coal entering the gasifier of 0.3-0.8. The actual detected values ​​of the silicon-aluminum ratio of the mixed coal are 2.18, 2.67, and 2.52 respectively, and the silicon-aluminum ratio of the mixed coal fed into the gasifier is controlled to be 2 to 3. The above results show that mixing different types of coal according to the mass ratio calculated by the present invention can meet the coal requirements of the gasifier.

[0146] At the same time, the actual detection values ​​of the above-mentioned mixed coal indicators (water content in mixed coal, mixed coal ash content, mixed coal ash melting point, mixed coal alkali-acid ratio and mixed coal silicon-aluminum ratio) are compared with the calculated values ​​calculated using the formula. The calculated values ​​corresponding to each indicator are not much different from the actual detection values. For example, the actual detection values ​​of the mixed coal ash content are 7.74wt%, 9.87wt%, and 8.8wt%, respectively, and the calculated values ​​of the mixed coal ash content are 7.97wt%, 9.19wt%, and 8.53wt%, respectively. The actual detection value of the mixed coal ash content and the calculated value of the mixed coal ash content are within the error range. This shows that the coal quality selection calculation formula provided by the present invention is reasonable and can be used in the selection of coal quality for gasifiers.

[0147] (4) Detection of viscosity-temperature characteristics of mixed coal

[0148] Table 8 Analysis of viscosity-temperature characteristics of mixed coal using three mixed coal ratios

[0149]

[0150] The viscosity-temperature characteristic curve of coal ash slag is as follows: Figure 1 to Figure 3 shown.

[0151] See also Figure 1 , Figure 2 and Figure 3 The optimal viscosity of the coal ash viscosity-temperature characteristics is 3-25Pa.s. Coal with a wide temperature range is conducive to gasification operation. The three mixed coals are blended in different proportions, coal 1: coal 2: coal 3 = 1:1:1, 3:5:2, 4:4:2. The mixed coal has good viscosity-temperature characteristics, a wide operating temperature range and low temperatures, respectively: 1185-1358℃ / 1183-1311℃ / 1175-1345℃, which can meet the design requirements of coal quality entering the gasifier.

[0152] In the present invention, the particle size requirement for the raw coal entering the gasifier is ≤10mm, and the proportion of raw coal with larger particle size is minimized. In this way, when the raw coal, coal grinding water, and additives of each type of coal enter the coal mill in proportion and are ground into qualified coal slurry, that is: the coal slurry particle size ≤200 mesh accounts for ≥50%; the coal slurry concentration is 60%, the viscosity is 500-1000mpa.s, and the coal slurry water separation rate is ≤4%. The coal slurry formed in this way has good fluidity and stability. It should be noted that the proportion of raw coal, coal grinding water, and additives adopts the proportion formed by conventional gasifier water-coal slurry. This mixing ratio is the prior art and is not limited here.

[0153] In the present invention, qualified water-coal slurry formed by raw coal of different types of coal is sprayed into the gasifier together with high-pressure oxygen from the air separation system, and a partial oxidation reaction is carried out in the combustion chamber of the gasifier to generate crude synthesis gas and slag. The crude synthesis gas is washed with quenching water and then discharged from the gasifier; the slag is cooled and solidified by quenching water, settles to the bottom of the washing and cooling chamber, and is crushed by a static slag breaker and then entrained by the circulating water of the lock bucket into the lock bucket and discharged into the slag pool regularly, and the residual carbon content of the slag is not higher than 1.5%. During the implementation process, when the coal blending ratio entering the gasifier changes, the melting point of the coal slurry ash also changes accordingly. At this time, it is also necessary to adjust the furnace temperature in time to ensure that the gasifier is discharged normally. The method for adjusting the furnace temperature is the conventional adjustment method of the existing gasifier, which is not specifically limited here; in addition, the gasifier is operated according to the pressure load operating conditions to ensure the oxygen flow rate and atomization effect, and to avoid the gasifier from deviating from the load operation as much as possible.

[0154] The present invention takes the design standard of coal for gasifier as a benchmark, analyzes the quality of mixed coal, and adjusts the mass ratio (i.e., proportion) of coal entering the gasifier according to the coal quality analysis data and the design target of the coal quality entering the gasifier, so as to achieve the purpose of safe operation of the gasifier, improve the applicability of the coal quality entering the gasifier, and ensure the stable operation of the gasifier.

[0155] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for selecting coal quality for coal-water slurry gasification, characterized in that: The following steps are involved: S1. Obtain coal quality analysis data for different types of coal The coal quality analysis data of different types of coal include: internal water, ash content, alkali-acid ratio, silicon-aluminum ratio and flow temperature; the alkali-acid ratio is the ratio of the content of alkaline components to the content of acidic components; the silicon-aluminum ratio is the ratio of the content of silicon components to the content of aluminum components; S2. Construct the relationship between the coal quality analysis data of different types of coal and the water content of mixed coal, mixed coal ash content, mixed coal ash melting point, mixed coal alkali-acid ratio and mixed coal silicon-aluminum ratio of mixed coal, as follows: Water in mixed coal: Mixed coal ash content: Mixed coal ash melting point: Alkali-acid ratio of mixed coal: Silicon-aluminum ratio of mixed coal: Wherein: n is the number of coal types; N1, N2, N3..., Nn are the mass parts of each coal type, M1, M2, M3..., Mn are the internal water content of each coal type; Ad1, Ad2, Ad3..., Adn are the ash content of each coal type; T1, T2, T3..., Tn are the flow temperature of each coal type; are the alkali-acid ratio of each type of coal; are the silicon-aluminum ratio of each type of coal; B1, B2, B3, ..., Bn are the total content of alkaline components in each type of coal; A1, A2, A3, ..., An are the total content of acidic components in each type of coal; S1, S2, S3, ..., Sn are the silicon content in each type of coal; Al1, Al2, Al3, ..., Aln are the aluminum content in each type of coal; S3. Substitute the coal quality analysis data of different types of coal obtained in step S1 into the formula of step S2 respectively, and calculate N1:N2:N3:...:Nn according to the target requirements of the mixed coal entering the gasifier for the water content in the mixed coal, the ash content in the mixed coal, the melting point of the mixed coal, the alkali-acid ratio in the mixed coal and the silicon-aluminum ratio in the mixed coal.

2. The method for selecting coal quality for water-coal slurry gasification according to claim 1, characterized in that: In step S1, the alkaline components refer to: SiO2 and Al2O3; the acidic components refer to: Fe2O3, CaO, MgO, K2O and Na2O; the silicon component is measured in SiO2, and the aluminum component is measured in Al2O3.

3. The method for selecting coal quality for water-coal slurry gasification according to claim 1, characterized in that: In step S3, the target requirements of the mixed coal entering the gasifier for the water content in the mixed coal, the ash content in the mixed coal, the melting point of the ash in the mixed coal, the alkali-acid ratio of the mixed coal, and the silicon-aluminum ratio of the mixed coal are: the water content in the mixed coal is less than 8%, the ash content in the mixed coal is less than 10%, the ash melting point in the mixed coal is less than 1300°C, the silicon-aluminum ratio of the mixed coal is 2-3, and the alkali-acid ratio of the mixed coal is 0.3-0.

8.

4. The method for selecting coal quality for coal-water slurry gasification according to claim 1, characterized in that: In step S1, different types of coal must also meet the following indicators: particle size ≤ 10 mm, residual carbon content in slag not higher than 1.5 wt%, volatile matter 25 wt% to 35 wt% and fixed carbon 45 wt% to 60 wt%.

5. The method for selecting coal quality for water-coal slurry gasification according to claim 1, characterized in that: In step S3, the slurry properties of the mixed coal fed into the gasifier meet the following requirements: coal slurry particle size ≤ 200 mesh, accounting for ≥ 50%, coal slurry concentration 60%, viscosity 500-1000 mpa.s, and coal slurry water separation rate ≤ 4%.

6. The method for selecting coal quality for water-coal slurry gasification according to claim 4, characterized in that: In step S3, the viscosity-temperature characteristics of the coal ash of the mixed coal fed into the gasifier meet the following requirements: the viscosity of the coal slurry is 3-25 Pa.s.

7. The method for selecting coal quality for coal-water slurry gasification according to claim 4, characterized in that: In step S3, the operating temperature of the mixed coal fed into the gasifier is 1100°C to 1400°C.

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