CN106675657A - Method for regulating and controlling flowing temperature of high-melting-point coal ash - Google Patents

Abstract

A method for controlling the flow temperature of coal ash with high melting point. The ash melting point is measured for coals with coal ash lower than 25% and Al ₂ O ₃ content in the ash lower than 40%. For the coal type with ash FT>1400℃, one or more types of coals are used to blend coal with the coal type according to different qualities, so that the coal ash A/B of the mixed coal is less than 4.3, and then the mixed coal is ashed to measure the mixed coal. Coal ash FT, if the mixed coal ash FT meets the ideal operating temperature of the gasifier, it can be used directly; if the mixed coal ash FT does not meet the ideal operating temperature of the gasifier, the coal ash can be further regulated by adding additives. This method not only broadens the adaptability of the high melting point coal ash to the entrained bed gasification process, but also reduces the additive amount while ensuring the calorific value of the mixed coal.

Description

A method of regulating the flow temperature of coal ash with high melting point

technical field

The invention belongs to the field of coal entrained bed gasification, and in particular relates to a method for regulating the flow temperature of coal ash with high melting point.

Background technique

As we all know, China's energy structure is poor in oil, low in gas, and relatively rich in coal, so that China's coal-dominated pattern will not change for a long time. Compared with oil and natural gas, coal is a highly polluting energy source. For this reason, the future development of coal must follow a high-tech, low-pollution road. Among them, coal gasification is the "leader" and foundation for the clean utilization of coal. Entrained bed gasification technology has become the main development direction in the future due to its advantages of large production capacity and high conversion rate. The requirements for ash content of entrained bed gasifiers are generally between 5% and 25%, and the operating temperature is generally 1400-1600°C. Gasifiers with different furnace types and operating modes have different requirements on the flow temperature (FT) of coal ash. There are certain differences in requirements, but the process of liquid slag discharge requires FT to be at least lower than 1400°C, and the coal types with coal ash FT greater than 1400°C in my country account for about 57% of the total, so there is an urgent need for melting of high melting point coal ash Features are improved. When the entrained bed gasifier operates at 1400-1600°C, coal ash with a low FT has enhanced fluidity after melting, and has obvious erosion and penetration effects on refractory bricks, resulting in a greatly reduced service life of refractory bricks. Studies have shown that the operating temperature of the gasifier is 50-100°C higher than the coal ash FT, which is ideal. Therefore, based on the composition of the coal ash itself, it is possible to find the enrichment area of the coal ash FT through different "key components". important practical significance.

The current research shows that the melting temperature of the coal ash is higher when there are more acid components in the coal ash, and when the Al ₂ O ₃ content in the coal ash is higher than 40%, it is difficult to control its FT below 1400°C; When there are more alkaline components in the coal ash, the melting temperature of the coal ash is lower. At this stage, the common methods to improve the melting characteristics of coal ash are coal blending or the use of alkaline inorganic salt additives. With the method of coal blending, it is difficult to determine the ideal coal blending ratio at one time due to the ash content of different coal types and the difference in the content of each component in the ash. The use of alkaline inorganic salt additives will lead to a direct increase in the ash content of the coal ash. Under the same operating conditions, for every 1% increase in the ash content of the coal ash, the oxygen consumption will increase by 0.7%-0.8%, and the coal consumption will increase by 1.3%-1.5% %.

Patent CN 101580751A discloses an additive for reducing the fusion temperature of coal ash. The main content is: 30-60 parts of SiO ₂ , CaO, Fe ₂ O ₃ , MgO in different proportions and a certain amount of Al ₂ O ₃ , Na ₂ O, K ₂ O are added on this basis to prepare composite additives. However, it does not specify the suitable coal type and dosage range of this additive; for the regulation of different coal types, the blending components and dosage of the additive are different, which makes the preparation of the additive more cumbersome.

Patent CN 105542901A discloses a method for reducing the fusion temperature of coal ash. The main content is: adding one or more of CaO, MgO, Fe ₂ O ₃ , or adding salts capable of decomposing at least one of CaO, MgO, Fe ₂ O ₃ . This patent only uses additives to reduce the melting temperature of coal ash, but directly increases the ash content of coal, which in turn reduces the calorific value and indirectly increases the energy consumption of coal gasification.

Patent CN105199811A discloses a flux for lowering the melting temperature of coal ash. The main content is: in three kinds of coal ash with FT higher than 1500°C, by adding different qualities of alkaline flux (limestone, calcite, mica) to Reduced soot ft. This patent is only researched on the basis of three kinds of coal ash with high melting point, and its representativeness is slightly insufficient. Moreover, when adjusting the FT of coal ash, it is carried out by adding ore-based flux. While reducing the FT of coal ash, it is also The ash content is increased and the calorific value of coal is reduced.

Contents of the invention

In order to overcome the problems existing in the prior art, the invention provides a method for regulating and controlling the flow temperature of coal ash with high melting point, which reduces energy consumption, is simple and convenient, and ensures the calorific value of mixed coal.

To achieve the above object, the present invention adopts the following technical solutions,

A method for controlling the flow temperature of coal ash with high melting point. The ash melting point is measured for coals with coal ash lower than 25% and Al ₂ O ₃ content in the ash lower than 40%. For the coal type with ash FT>1400℃, one or more types of coals are used to blend coal with the coal type according to different qualities, so that the coal ash A/B of the mixed coal is less than 4.3, and then the mixed coal is ashed to measure the mixed coal. Coal ash FT, if the mixed coal ash FT meets the ideal operating temperature of the gasifier, it can be used directly; where A/B is the acid-base ratio of coal ash, and A/B=(SiO ₂ +Al ₂ O ₃ +TiO ₂ )/(CaO+Fe ₂ O ₃ +MgO);

If the mixed coal ash FT does not meet the ideal operating temperature of the gasifier, it can be divided into the following three situations, and the coal ash should be further adjusted:

1) When 1.0≦A/B<3.0, add acidic additives or basic additives to further control the FT of coal ash, so that 0.30≦Al ₂ O ₃ /(CaO+Fe ₂ O ₃ )<0.85, this When FT=1215±55℃; or make 0.85≦Al ₂ O ₃ /(CaO+Fe ₂ O ₃ )<1.50, then FT=1335±40℃;

2) When 3.0≦A/B<4.3, add alkaline additives so that 1.00≦SiO ₂ /Al ₂ O ₃ <2.30, then FT=1350±60℃, or make 2.30≦SiO ₂ /Al ₂ O ₃ <3.20, at this time FT＝1255±35℃;

3) When 3.0≦A/B<4.3, and 1.00≦SiO ₂ /Al ₂ O ₃ <3.20, if FT>1400℃, add alkaline additives so that 3.0≦A/B<3.5, at this time coal Ash FT meets the requirement of FT<1400℃ for liquid slagging process.

A further improvement of the present invention is that the acidic additive is one or more of SiO ₂ , Al ₂ O ₃ or kaolin.

A further improvement of the present invention lies in that the alkaline additive is one or more of CaO, Fe ₂ O ₃ , and MgO, or one or more of calcium carbonate, iron carbonate, and magnesium carbonate.

Compared with the prior art, the present invention has the beneficial effects of:

(1) The present invention aims at coal types with FT>1400°C caused when there are many acidic components in the coal ash, that is, when the coal ash A/B>4.3, which highlights the pertinence of the present invention.

(2) The present invention adopts the method of coal preparation-coal blending or coal preparation-coal blending-addition of additives to regulate the FT of high melting point coal ash. The coal type used for entrained bed gasification reduces the amount of additives added and ensures the calorific value of the mixed coal, so the present invention has strong applicability.

(3) The present invention not only takes the adjustment of A/B as the main control means, but also divides the A/B of different ranges according to the effect of the acid and alkali components of coal ash at high temperature, and finds out the value of A/B in 1.0≦A/ When B<3.0, the dominant factor affecting coal ash FT is Al ₂ O ₃ /(CaO+Fe ₂ O ₃ ), when 3.0≦A/B<4.3, the dominant factor affecting coal ash FT is SiO ₂ /Al ₂ O _3. Furthermore, the variable temperature range of the mixed coal ash FT is controlled at FT±60°C, and the "enrichment" of the coal ash FT is realized under a simple control process, so the present invention is easy to operate.

Furthermore, the additives used in the present invention are not only cheap and have a wide range of raw materials, but also simple and easy to operate.

Description of drawings

Fig. 1 is a process flow chart of the present invention for regulating and controlling coal ash FT.

Figure 2 shows the effect of coal ash A/B on coal ash FT.

Fig. 3 shows the effect of Al ₂ O ₃ /(CaO+Fe ₂ O ₃ ) on FT when 1.0≦A/B<3.0.

Figure 4 shows the effect of SiO ₂ /Al ₂ O ₃ on FT when 3.0≦A/B<4.3.

detailed description

The present invention will be described in detail below in conjunction with the accompanying drawings.

The ideal operating temperature of the gasifier of the present invention is a temperature 50-100°C higher than the flow temperature of coal ash.

The present invention comprises the following steps, and the specific process is referring to Fig. 1:

(1) Carry out industrial analysis to coal, and ashing treatment, carry out ash analysis and A/B analysis, determine whether the ash content is higher than ₂₅ %, whether the _Al2O3 content in the ash is higher than 40%;

(2) For coal types with coal ash lower than 25% and Al ₂ O ₃ content in ash lower than 40%, the ash melting point is measured. For coal types with coal ash FT>1400°C caused by A/B>4.3, That is, relational formula 3. The research results are shown in Figure 2. Using one or more types of coals that are significantly different from their coal ash acid and alkaline components, according to the relationship between A/B and FT in relational formula 1-2, take Blend coal with different mass ratios, adjust the FT of the coal ash, then ash the mixed coal, measure the FT of the mixed coal ash, and use it directly if the FT of the mixed coal ash after coal blending meets the ideal operating temperature of the gasifier .

Relational formula 1: 1.0≦A/B<3.0, 1160<FT<1375℃;

Relational formula 2: 3.0≦A/B<4.3, 1220<FT<1410℃;

Relational formula 3: A/B≧4.3, FT>1400℃

In the formula, A/B is the acid-base ratio of coal ash, A/B=(SiO ₂ +Al ₂ O ₃ +TiO ₂ )/(CaO+Fe ₂ O ₃ +MgO), that is, SiO ₂ , Al ₂ O ₃ and The ratio of the total mass percent of _TiO2 to the total mass percent of CaO, _Fe2O3 and MgO _;

(3) If the FT of the mixed coal ash after coal blending still does not meet the ideal operating temperature of the gasifier, the key factors affecting the melting temperature of the coal ash are used as the basis for regulation, and the method of adding additives is used for further regulation. Regulating additives are divided into acidic additives and basic additives; acidic additives are one or more of SiO ₂ and Al ₂ O ₃ , or minerals rich in SiO ₂ and Al ₂ O ₃ , such as kaolin, etc.; Alkaline additives are one or more of CaO, Fe ₂ O ₃ , MgO, or minerals that can decompose oxides such as CaO, Fe ₂ O ₃ , and MgO at high temperatures, such as: calcium carbonate, iron carbonate, Magnesium carbonate, etc.

(4) When 1.0<A/B<4.3, the method of dividing A/B and cooperating with the key factors affecting the melting temperature of coal ash is used for research. The study found that when 1.0<A/B<3.0, the coal ash FT has a great correlation with the mass ratio of Al ₂ O ₃ /(CaO+Fe ₂ O ₃ ). The research results are shown in Figure 3; when 3.0<A/B When B<4.3, the coal ash FT has a greater correlation with the mass ratio of SiO ₂ /Al ₂ O ₃ , and the research results are shown in Figure 4.

1) When 1.0≦A/B<3.0, add acidic additives or basic additives to further control the FT of coal ash, so that 0.30≦Al ₂ O ₃ /(CaO+Fe ₂ O ₃ )<0.85, this When FT=1215±55℃; or make 0.85≦Al ₂ O ₃ /(CaO+Fe ₂ O ₃ )<1.50, then FT=1335±40℃;

2) When 3.0≦A/B<4.3, add alkaline additives so that 1.00≦SiO ₂ /Al ₂ O ₃ <2.30, then FT=1350±60℃, or make 2.30≦SiO ₂ /Al ₂ O ₃ <3.20, at this time FT＝1255±35℃;

3) When 3.0≦A/B<4.3, and 1.00≦SiO ₂ /Al ₂ O ₃ <3.20, if FT>1400℃, add alkaline additives so that 3.0≦A/B<3.5, at this time coal Ash FT meets the requirement of FT<1400℃ for liquid slagging process.

See the following formula for details:

I:

II:

III: Under the condition of II-①, if FT>1400°C, add an alkaline additive to control the coal ash A/B at 3.0≦A/B<3.5. The present invention will be described in detail through specific implementation cases below.

Example 1

(1) Select typical high melting point Jincheng anthracite (JC) and low melting point Xiangyang coal (XY) for industrial analysis and analysis of various components in coal ash to analyze whether the ash content is higher than 25%, Al ₂ O ₃ content Is it higher than 40%. According to industrial analysis, the ash content of the _two coals is less than 25%, and the _Al2O3 content is less than 40%.

(2) Calculate the A/B of different proportions according to the ash analysis results, and the results are shown in Table 1.

Table 1 Analysis of the mixed coal ash of Xiangyang coal and Jincheng anthracite

project SiO ₂ A1 ₂ O _{3 Fe2O3 _} CaO MgO TiO ₂ A/B JC 47.00 33.55 7.99 5.16 1.60 0.85 5.52 10%XY 45.75 31.04 8.85 7.00 1.71 0.84 4.42 20%XY 44.43 30.45 9.76 8.94 1.82 0.83 3.69 30%XY 43.05 28.79 10.7 10.97 1.94 0.82 3.08 40%XY 41.60 27.04 11.71 13.1 2.01 0.81 2.59 50%XY 40.08 25.2 12.75 15.35 2.20 0.81 2.18 X Y 31.06 14.32 18.95 28.62 2.98 0.74 0.91

Note: 10%, 20%, 30%, 40%, and 50% in 10%XY, 20%XY, 30%XY, 40%XY, and 50%XY all represent the mass percentage of XY added.

(3) Guided by the temperature range corresponding to A/B in the above relationship 1-3, according to the mass percentage, add different masses of XY to JC respectively to prepare a mixed coal sample, and the particle size of the coal sample is controlled below 0.1mm .

Mixed coals were ashed at 815°C, ash samples with different coal sample ratios were taken out, ash cones were prepared respectively, and the ash cones were placed in a weak reducing atmosphere, using an intelligent ash melting point tester to measure the corresponding coal ash Melting characteristic temperature: deformation temperature (DT), softening temperature (ST), hemispherical temperature (HT) and flow temperature (FT). See Table 2 for FT of mixed coal ash.

Table 2 Analysis of coal ash FT and corresponding parameters in different proportions

(4) It can be known from Table 1 and Table 2 that the A/B of JC and 10% XY are both greater than 4.3 and the measured FT is greater than 1400°C. This experimental result verifies the feasibility of relational formula 3; the mass percentage of XY coal in the mixed coal For example, when it is 20% and 30%, the coal ash A/B is between 3.0≦A/B<4.3, and the measured FT is 1404°C and 1360°C, both in the range of 1220-1410°C. The experimental results The feasibility of relational formula 2 is also verified; when the proportion of XY coal in the mixed coal is 40% and 50%, the coal ash A/B is between 1.0≦A/B<3.0, and the measured FT is 1368°C, 1330°C, both in the range of 1160-1375°C, the experimental results also verified the feasibility of relational formula 1. If the mixed coal ash FT meets the process requirements after coal blending, it can be used directly; if the mixed coal ash FT after coal blending does not meet the process requirements, it can be regulated again by adding additives.

Obviously, for the mixed coal with XY coal ratio of 20%, the FT of the mixed coal ash is 1404℃>1400℃, which exceeds the upper limit requirement, but only exceeds 4℃, so the method of adding alkaline additives is used for fine-tuning. Auxiliaries are divided into acidic auxiliaries (SiO ₂ , Al ₂ O ₃ or kaolin and other minerals containing more SiO ₂ and Al ₂ O ₃ ) and basic auxiliaries (CaO, Fe ₂ O ₃ , MgO or CaO can be decomposed , Fe ₂ O ₃ , easily decomposable salts of such substances as MgO), the specific control operation is as follows:

I:

II:

III: If under the conditions of II-①, FT>1400℃, add alkaline additives so that 3.0≦A/B<3.5

Add 1.0% to 5.0% CaO of the mass of the ash base (20% XY) using the relational formula III, and adjust the A/B of the mixed coal ash to the range of 3.0≦A/B<3.5, so that FT<1400°C. Taking the addition of 2.0% CaO as ash base as an example, its A/B drops to 3.36, and the measured coal ash FT=1382°C, reaching the expected goal.

Example 2

(1) Select typical high-melting-point Jincheng anthracite (JC) and Shenhua coal direct liquefaction residue (DCLR) for industrial analysis and analysis of various components in coal ash to analyze whether the ash content is higher than 25%, Al ₂ O ₃ Whether the content is higher than 40%. The ash content of both samples was less than 25% by industrial analysis.

(2) Calculate the A/B of different proportions according to the ash analysis results, and the results are shown in Table 3.

Table 3 Analysis of mixed coal ash of Shenhua coal direct liquefaction residue and Jincheng anthracite

project SiO ₂ A1 ₂ O _{3 Fe2O3 _} CaO MgO TiO ₂ A/B JC 47.00 33.55 7.99 5.16 1.60 0.85 5.52 10%DCLR 44.86 31.54 9.47 6.00 1.55 0.95 4.55 20%DCLR 42.64 29.45 11.00 6.87 1.49 1.05 3.78 30%DCLR 40.33 27.27 12.60 7.77 1.43 1.16 3.15 40%DCLR 37.93 25.02 14.25 8.71 1.37 1.27 2.64 50%DCLR 35.44 22.67 15.98 9.69 1.31 1.39 2.21 DCLR 21.30 9.37 25.74 15.23 0.95 2.05 0.78

Note: 10%, 20%, 30%, 40%, and 50% in 10%DCLR, 20%DCLR, 30%DCLR, 40%DCLR, and 50%DCLR all represent the mass percentage of DCLR added.

(3) Guided by the temperature range corresponding to A/B in the above relationship 1-3, according to the mass percentage, add different masses of DCLR to JC respectively to prepare mixed coal samples, and the particle size of the coal samples is controlled below 0.1mm .

Mixed coals were ashed at 815°C, ash samples with different coal sample ratios were taken out, ash cones were prepared respectively, and the ash cones were placed in a weak reducing atmosphere, using an intelligent ash melting point tester to measure the corresponding coal ash Melting characteristic temperature: deformation temperature (DT), softening temperature (ST), hemispherical temperature (HT) and flow temperature (FT). See Table 4 for FT of mixed coal ash.

Table 4 Analysis of coal ash FT and corresponding parameters in different proportions

(4) It can be seen from Table 3 and Table 4 that the A/B of JC and 10% DCLR are both greater than 4.3 and the measured FT is greater than 1400°C. This experimental result verifies the feasibility of relational formula 3; the mass ratio of DCLR in the mixed coal is At 20% and 30%, the coal ash A/B is between 3.0≦A/B<4.3, and the measured FT is 1408°C and 1384°C respectively, both in the range of 1220-1410°C. This test result also verifies The feasibility of relational formula 2 is confirmed; when the DCLR ratio in the coal blend is 40% and 50%, the coal ash A/B is between 1.0≦A/B<3.0, and the measured FT is 1372°C and 1332°C, respectively. Both are in the range of 1160-1375°C, and the experimental results also verify the feasibility of relation 1. If the mixed coal ash FT meets the process requirements after coal blending, it can be used directly; if the mixed coal ash FT after coal blending does not meet the process requirements, it can be regulated again by adding additives.

Obviously, for the blended coal with a DCLR ratio of 20%, the FT of the blended coal ash is 1408°C > 1400°C, which exceeds the upper limit requirement, but only exceeds 8°C, so it is fine-tuned by adding alkaline additives. Auxiliaries are divided into acidic auxiliaries (SiO ₂ , Al ₂ O ₃ or kaolin and other minerals containing more SiO ₂ and Al ₂ O ₃ ) and basic auxiliaries (CaO, Fe ₂ O ₃ , MgO or CaO can be decomposed , Fe ₂ O ₃ , easily decomposable salts of such substances as MgO), the specific control operation is as follows:

I:

II:

III: If under the conditions of II-①, FT>1400℃, add alkaline additives so that 3.0≦A/B<3.5

Add 1.6% to 5.1% CaO of the mass of the ash base (20% DCLR) using relational formula III, and then adjust the A/B of the mixed coal ash to the range of 3.0≦A/B<3.5, so that FT<1400°C. Taking the addition of 3.0% CaO as an example, the A/B drops to 3.27, and the measured coal ash FT = 1378°C, reaching the expected goal.

Claims (3)

1. it is a kind of regulate and control high-melting-point coal ash flowing temperature method, it is characterised in that：To coal ash less than Al in 25%, ash₂O₃Content Coal less than 40%, carries out ash fusion point measure, to because of A/B>The 4.3 coal ash FT for causing>1400 DEG C of coal, using a kind of or Various coals carry out coal blending with the coal according to different quality so that the coal ash A/B of Mixture Density Networks<4.3, ash then is carried out to Mixture Density Networks Change is processed, and determines blended coal ash FT, if blended coal ash FT meets the ideal operating temperatures of gasification furnace, is directly used；Wherein, formula Middle A/B is the soda acid ratio of coal ash, and A/B=(SiO₂+Al₂O₃+TiO₂)/(CaO+Fe₂O₃+MgO)；

If blended coal ash FT is unsatisfactory for the ideal operating temperatures of gasification furnace, it is divided into following 3 kinds of situations, coal ash is carried out further Regulation and control：

1) as 1.0≤A/B<When 3.0, add acid additive or add alkaline assistant further to regulate and control to coal ash FT so that 0.30≦Al₂O₃/(CaO+Fe₂O₃)<0.85, now FT=1215 ± 55 DEG C；Or cause 0.85≤Al₂O₃/(CaO+Fe₂O₃)< 1.50, now FT=1335 ± 40 DEG C；

2) as 3.0≤A/B<When 4.3, alkaline assistant is added so that 1.00≤SiO₂/Al₂O₃<2.30, now FT=1350 ± 60 DEG C, or cause 2.30≤SiO₂/Al₂O₃<3.20, now FT=1255 ± 35 DEG C；

3) as 3.0≤A/B<4.3, and 1.00≤SiO₂/Al₂O₃<When 3.20, if FT>1400 DEG C, then add alkaline assistant so that 3.0≦A/B<3.5, now coal ash FT meet slag tap technique to FT<1400 DEG C of requirement.

2. it is according to claim 1 regulation and control high-melting-point coal ash flowing temperature method, it is characterised in that：The acid additive It is SiO₂、Al₂O₃In one or more or kaolin.

3. it is according to claim 1 regulation and control high-melting-point coal ash flowing temperature method, it is characterised in that：The alkaline assistant It is CaO, Fe₂O₃, one or more in one or more of MgO or calcium carbonate, ferric carbonate, magnesium carbonate.