CN105001914A - Coking fly ash-doped coal co-gasification method - Google Patents

Abstract

A method for co-gasification of coking dedusting ash mixed with coal belongs to the technical field of coal gasification, and the steps are as follows: 1) respectively subjecting the coal sample and coking dedusting ash to ash content, volatile matter, ash chemical composition, ash melting temperature and _CO2 gasification reaction 2) According to the ash content, volatile matter, ash chemical composition, ash melting temperature and CO ₂ gasification reactivity index R _0.5 of the coal sample and coking dust, mix the coal sample and coking dust in proportion to obtain a mixed coal sample ; 3) Send the mixed coal sample into the gasifier for gasification. The co-gasification of coal gasification with coking dust removal ash can not only increase the output of effective gas, but also significantly reduce the cost of raw materials, thereby improving the economic benefits of coal gasification enterprises. The company solved the problem that a large amount of coking dust could not be handled.

Description

Co-gasification method of coking dust removal ash mixed with coal

technical field

The invention belongs to the technical field of coal gasification, and in particular relates to a co-gasification method of coking dust and dust mixed with coal.

Background technique

Coking plants will produce a large amount of dust removal ash in the traditional coal charging and coke pushing process, especially in recent years, with the application of CDQ technology, the output of dust removal ash in coking plants is increasing day by day. According to statistics, the output of coking dust removal ash Accounting for about 4% of the total output of coke, the accumulation of a large amount of dust not only causes waste of resources, but also pollutes the environment. The test and analysis show that coking dust has the characteristics of high fixed carbon content, low volatile matter and high content of alkaline components. Therefore, most existing enterprises mix coking dust back into coking, or replace part of anthracite with dust as a The blast furnace in the metallurgical industry injects fuel, which not only realizes the recycling of dust and reduces environmental pressure, but also reduces the production and processing costs of coking and metallurgical industries, which has certain economic benefits.

However, in the actual production process, in order to ensure continuous and stable production, the proportion of coking dust ash mixed with coking coal should not exceed 20% of the coal sample used for coking. The proportion is less (≤5%), which makes the large amount of coking dust generated in coking plants unable to be completely reused, and the coking dust generated in some coking plants accumulates in the factory area, and the granular dust generated seriously affects the health of workers. Therefore, it is a problem that technicians have been considering to find a new way to utilize the coking dedusting ash.

Contents of the invention

The primary purpose of the present invention is to provide a co-gasification method of coking dust removal ash mixed with coal which is convenient to use and can effectively ensure continuous production.

In order to achieve the above object, the present invention adopts the following technical solutions: a method for co-gasification of coking dust removal ash mixed with coal, the steps are as follows:

S1) Determination of ash content, volatile matter, ash chemical composition, ash melting temperature and _CO gasification reactivity of the coal sample and coking dedusting ash respectively;

S2) According to the ash content, volatile matter, ash chemical composition, ash melting temperature and CO ₂ gasification reactivity index R _0.5 of the coal sample and coking dedusting ash measured in step S1), mix the coal sample and coking dedusting ash in proportion to obtain Mixed coal samples, control the ash content of the mixed coal samples to 18%-20%, the volatile matter to 6%-8%, the ratio of the mass content of acidic oxides to basic oxides in the ash to be 4.8-5.2, and the ash flow temperature 1340-1380℃, CO ₂ gasification reactivity index R _0.5 is (6.5-6.8)*10 ^-3 ; reactivity index R _0.5 =0.5/t _0.5 is an important parameter for thermogravimetric analysis of coal char reactivity, where t _0.5 refers to the time when the carbon conversion reaches 50% at the same heating rate. At the same heating rate, the larger R _0.5 , the better the reactivity.

S3) Send the mixed coal sample into the gasifier for gasification.

The beneficial effects of adopting the above-mentioned technical solutions are: in view of the problem that 57% of my country’s coal reserves with high ash melting point coal are difficult to be directly used for entrained bed gasification, most enterprises purchase low ash melting point coal, or fluxes combined with these high The ash melting point is matched with coal to reduce the melting temperature of coal ash. In comparison, the present invention mixes coal with coking dust removal ash for co-gasification, which can not only solve the problems of narrow utilization range of coking dust removal ash and environmental pollution, but also the raw materials are easy to obtain and the price is low. The most important thing is that it can effectively improve the ash melting temperature and viscosity-temperature characteristics of high ash melting point coal, so that high ash melting point coal can be safely and stably put into the gasifier for gasification. Specifically, it has been verified by experiments that, compared with the mixed gasification of two types of coal with high and low coal ash melting points, co-gasification using coking dust removal ash mixed with coal can not only increase the output of effective gas, but also significantly reduce the cost of raw materials, which can effectively Improve the economic benefits of coal gasification enterprises. At the same time, reusing the coking dust generated by coking enterprises also solves the problem that a large amount of coking dust cannot be processed for coking enterprises, and improves their economic income.

As a further preferred solution: the ash flow temperature of the coal sample in the step S1 is 1500-1600°C, and the flow temperature of the coking dust removal ash is between 1300-1330°C. The flow temperature of dedusting ash is relatively low. In order to ensure the continuous and stable operation of the coal gasifier, it is preferable to use coal samples with ash flow temperature between 1500-1600°C and coking dedusting ash for co-gasification.

The specific scheme is that the coking dedusting ash and the coal sample in the step S1 are all ground to a particle size below 0.2mm before measuring the ash content, volatile matter, ash chemical composition, ash melting temperature and _CO gasification reactivity. Experiments have proved that the coking dust and coal samples are first ground to a particle size below 0.2mm, so that the measured data such as ash content, volatile matter, and ash chemical composition can better determine the mixing ratio of coking dust and coal samples Provide evidence.

Preferably, the mass ratio of the coking dedusting ash to the coal sample in the mixed coal sample in step S2 is (14-18):100. A number of coal samples with high ash melting point were collected from different mining areas in the Lianghuai area, and each coal sample was made into a coal sample for analysis according to the national standard. Considering the characteristics of the coal ash of these coal samples, it is preferable to use the above ratio to mix the coking and dust removal ash. Co-gasification of coal blending not only makes full use of coking dust and dust, reduces the processing pressure of coking enterprises, but also effectively ensures the safe, stable and continuous operation of coal gasification production. Specifically, through analysis and calculation, it is known that the mixed coal sample obtained by mixing the above proportions has high synthesis gas composition and effective gas flow rate, and the specific oxygen consumption and specific coal consumption are reduced, so it can bring huge economic benefits to the enterprise.

Description of drawings

Figure 1 is the _CO2 gasification reactivity curve of mixed coal samples;

Figure 2 is the coal ash viscosity-temperature characteristic curve of the mixed coal sample.

The shaded area is the area of viscosity 2.5-25pa.s. It is generally required that the viscosity value of coal ash at 1300-1450°C be controlled between 2.5-25Pa·s, further illustrating that the sample viscosity of the coal sample 1+14% dust removal ash in the embodiment of the present invention is relatively low when the viscosity is 25Pa·s ,Better results.

Detailed ways

The technical solution disclosed by the present invention will be further described through the following examples, but the present invention is not limited to the following examples.

Example

1) Collect coal samples and coking dedusting ash (hereinafter referred to as dedusting ash), and grind them separately until the particle size is below 0.2mm.

2) Measure the ash content, volatile matter, ash chemical composition, ash melting temperature, and _CO2 gasification reactivity of the ground coal sample and dedusted ash respectively. The specific measurement results are shown in Table 1-4, wherein coal sample 1 is the sample coal sample, coal sample 2 is the control coal sample;

3) According to the ash content, volatile matter, ash chemical composition, ash melting temperature and _CO2 gasification reactivity determination of the coal sample and dedusting ash measured in Table 1-4, dedusting ash and coal sample according to (14-18): The mass ratio of 100 is mixed to obtain a mixed coal sample, so that the ash content of the mixed coal sample is 18%-20%, the volatile content is 6%-8%, and the ratio of acid oxide to basic oxide content in the ash is 4.8-5.2 , Ash flow temperature is 1340-1380℃, CO ₂ gasification reactivity index R _0.5 is (6.5-6.8)*10 ^-3 , at the same time, (5-12):100 and 20:100 for dust removal ash and coal sample The mixed coal sample obtained by mixing the mass ratio has also been measured as a comparative example, compared with the disclosed embodiments of the present invention;

4) Send the mixed coal sample obtained by blending the dedusted ash into the gasifier for gasification.

Table 1 Industrial analysis results of coal samples and dust

Among them, A _ad - ash content, V _ad - volatile matter.

Table 2 Industrial analysis results of coal samples and dust

Table 3 Ash melting temperature of coal sample, dedusted ash, and mixed coal sample blended with dedusted ash

Among them: "coal sample + 5% dedusting ash" refers to the addition of 5% dedusting ash in the coal sample, and so on.

Table 4 _CO2 gasification reactivity index R _0.5 of coal sample and dedusted ash

It can be seen from Table 3 that the flow temperature of selected coal sample 1 is greater than 1500 °C, which belongs to high ash melting temperature coal, while the melting temperature of dedusting ash is relatively low. Specifically, when the mass addition of dedusting ash is 10%, the ash flow temperature of coal sample 1 drops by 90°C, and when the mass addition of dedusting ash is 14%, the ash flow temperature of coal sample 1 has dropped below 1400°C, while Continue to increase the mass addition of dedusting ash, although the four coal ash melting characteristic temperatures of coal sample 1 show a downward trend, but the decline is not obvious.

It can be seen from Table 4 that the reactivity of coal sample 1 is higher than that of dust removal ash, and the reactivity of mixed coal samples is between the former two. The reactivity of the mixed coal sample shows a downward trend. Therefore, on the premise of ensuring that the ash fusion temperature of the mixed coal sample meets the requirements of entrained bed gasification, in order to prevent the decrease in the reactivity of the mixed coal sample from reducing the carbon conversion rate and effective gas production, the dust removal ash The ratio of blending should not be too high, preferably the mass addition amount of dedusting ash blended into coal sample 1 is within the range of 14%-18% in the present invention.

The CO ₂ gasification reactivity curve of the mixed coal samples mixed with different proportions of dedusting ash into coal sample 1 is shown in Figure 1.

Further, the coal sample 1 and the two mixed coal samples whose mass addition amount of dedusting ash were 12% and 14% were ashed, and the viscosity-temperature characteristics of the three ash samples were measured and compared, and the viscosity-temperature characteristics of the ash samples were measured. The curve is shown in Figure 2, from which it can be seen that the ash viscosity of coal sample 1 is relatively high; coal sample 1 is mixed with 12% dedusting ash The corresponding viscosity value of coal ash at 1450°C is greater than 25Pa·s; coal sample A mixed with 14% dedusting ash in coal sample 1 The viscosity-temperature curve of coal ash is relatively stable, and its corresponding viscosity value at 1415°C is less than 25Pa·s, which meets the requirements of an entrained bed gasifier. It can be seen that the use of the technical solution disclosed in the present invention for dust removal and ash blending with coal can ensure gasification. Safe and stable operation of the furnace.

In addition, under the same process conditions of gasification simulation calculation, the mixed coal sample A (mixed coal sample A is the mixed coal sample mixed with 14% dedusted ash in coal sample 1), and coal sample 1 mixed with 14% coal Compared with the gasification simulation results of mixed coal sample B composed of sample 2, the results are shown in Table 5:

Table 5 Gasification results of mixed coal samples

It can be seen from Table 5 that compared with mixed coal sample B, mixed coal sample A has higher syngas composition and effective gas flow rate, and lower specific oxygen consumption and specific coal consumption. Compared with co-gasification with high ash melting point coal, the use of dedusting ash blended with high ash melting point coal not only has high gasification benefits, but also has low price of dedusting ash. When used, it can effectively solve the problem of a large amount of coking dedusting ash accumulated in coking enterprises.

Claims (4)

1. coking dedusting ash mixes the method that coal gasifies altogether, it is characterized in that, its step comprises as follows:

S1) coal sample and coking dedusting ash are carried out ash content, volatile matter, grey chemical constitution, grey melt temperature and CO respectively ₂gasification activity measures;

S2) according to step S1) ash content of the coal sample that records and coking dedusting ash, volatile matter, grey chemical constitution, grey melt temperature and CO ₂gasification reaction sex index R _0.5coal sample and coking dedusting ash are mixed in proportion and obtain mixing coal sample, the ratio that the ash content quality controlling mixing coal sample is 18%-20%, volatile matter quality is acidic oxide and basic oxide mass content in 6%-8%, ash is 4.8-5.2, ash fluid point is 1340-1380 DEG C, CO ₂gasification reaction sex index R _0.5for (6.5-6.8) * 10 ^-3; Reactivity indexes R _0.5=0.5/t _0.5, wherein t _0.5refer to that efficiency of carbon conversion reaches the time of 50% under identical temperature rise rate;

S3) undertaken gasifying by mixing coal sample feeding vapourizing furnace.

2. mix according to a kind of coking dedusting ash of claim 1 method that coal gasifies altogether, it is characterized in that, step S1) in the ash fluid point of coal sample be 1500-1600 DEG C, the yield temperature of coking dedusting ash is between 1300-1330 DEG C.

3. mix according to a kind of coking dedusting ash of claim 1 method that coal gasifies altogether, it is characterized in that, step S1) in coking dedusting ash and coal sample at mensuration ash content, volatile matter, grey chemical constitution, grey melt temperature and CO ₂granularity is all milled at below 0.2mm before gasification activity.

4. mix according to a kind of coking dedusting ash of claim 1 method that coal gasifies altogether, it is characterized in that, step S2) mixing coal sample in the mass ratio of coking dedusting ash and coal sample be (14-18): 100.