CN106196009A - Fly ash and recycling method thereof - Google Patents

Abstract

The invention discloses a treatment method for recovering and reusing the fly ash of a coal-fired boiler. The fly ash of a coal-fired boiler is one of the main reasons for the heat loss of the boiler for mechanical wind power sowing coal. The fly ash of different periods is tested for testing. The average low calorific value of the fly ash as received is about 2500 kcal, and the fly ash has a combustible content of 38%. In order to reuse this part of the combustibles, the fly ash is collected and dried and mixed into coal for co-firing In order to improve the intensity of boiler suspension combustion, test different proportions of fly ash to find out the best proportion of fly ash blending. The method can effectively improve boiler combustion, reduce pollution, have significant effects on energy saving and consumption reduction, and is easy to implement and has very good applicable value.

Description

A kind of fly ash and its recycling method

technical field

The invention belongs to the technical field of industrial boilers, and in particular relates to a fly ash and a recovery and reuse method thereof.

Background technique

Based on the current boiler combustion mode, due to the transformation of the coal feeding system, the combustion method of the boiler is no longer a simple ram type coal feeding combustion, but a semi-suspension combustion, which requires that the particle size in the coal should be evenly distributed, and the pulverized coal and The proportion of particle size coal is relatively moderate. However, the current coal is difficult to be fully suitable for boiler combustion, which requires adjustment with pulverized coal. In addition, because the boiler fly ash is the main cause of the heat loss of the incomplete combustion of the boiler solid for the mechanical wind coal throwing. The fly ash of different periods was tested for testing. The test results showed that the average low calorific value of the fly ash as received was around 2500 kcal, which was consistent with the carbon content of the fly ash being 38%. The high carbon content of the fly ash increases the heat loss of the boiler, affects the flame height and the length of the fire bed in the vigorous combustion area, and is the direct cause of the low temperature in the furnace center.

Considering the existence of the above problems, it is necessary to study a way to optimize and perfect.

Contents of the invention

Aiming at the deficiencies of the prior art, the present invention provides a treatment method for reclaiming and reusing the fly ash of the cut cigarette block. By adding a suitable proportion of fly ash, the intensity of suspension combustion in the furnace is improved, and the unused fly ash in the fly ash is The burnt carbon is reused.

In order to solve the problems referred to above, the technology and method adopted in the present invention are as follows:

A fly ash that is added to coal combustion at a rate of 6%.

Further, the fly ash is unburned or incompletely burned fly ash.

Another technical problem to be solved by the present invention is to provide a method for recycling fly ash, comprising the following steps:

1) Desulfurization and dust removal treatment is carried out on the flue gas after combustion in the boiler to obtain the ash-water mixture for subsequent use;

2) Carry out slag removal treatment on the ash after combustion in the boiler to obtain the ash-water mixture and fly ash suspended on the water surface, for subsequent use;

3) Put the gray-water mixture in step 1) and step 2) into a high-level sedimentation tank together to obtain the gray-water mixture and fly ash suspended on the water surface for subsequent use;

4) Put the ash-water mixture obtained in step 3) into the slag yard, and wait for the ash-water to separate naturally to obtain fly ash for subsequent use;

5) Airing the fly ash in step 2), step 3) and step 4) until the moisture content in the fly ash is ≤8%;

6) Add the fly ash in step 5 into the boiler according to the ratio of 6%, and carry out mixed combustion.

Further, in step 5), the water content of the air-dried fly ash is tested, and the fly ash with a water content > 8% is air-dried again.

Further, the fly ash is unburned or incompletely burned fly ash.

Experimental steps:

1. Dry the fly ash floating on the water surface and deposited in the high-level sedimentation tank and the fly ash floating in the slag removal tank;

2. Sampling and testing the low calorific value of fly ash to select fly ash suitable for combustion;

3. According to the test results, according to the characteristics of the coal used, calculate the feasible theoretical ratio;

4. Put into the test according to the theoretical ratio;

5. Track the combustion conditions and collect corresponding cinder samples for laboratory analysis;

6. Statistically compare and analyze the coal consumption of the same steam production, and get the best fly ash addition ratio.

The beneficial effect of the invention is that the recovery and reuse of fly ash has remarkable effects in improving boiler combustion, reducing pollution, saving energy and reducing consumption, and is easy to implement and has very good application value.

Description of drawings

Fig. 1 is the flow chart of a kind of fly ash of the present invention and its recycling method;

Figure 2 is a curve diagram of boiler furnace temperature change.

detailed description

The present invention will be further described in detail below in conjunction with the embodiments and accompanying drawings, but they are not intended to limit the technical solution of the present invention. Any transformation made based on the teaching of the present invention falls within the protection scope of the present invention.

Referring to shown in Fig. 1, a kind of fly ash recycling method comprises the following steps:

1) Desulfurization and dust removal treatment is carried out on the flue gas after combustion in the boiler to obtain the ash-water mixture for subsequent use;

2) Carry out slag removal treatment on the ash after combustion in the boiler to obtain the ash-water mixture and fly ash suspended on the water surface, for subsequent use;

3) Put the gray-water mixture in step 1) and step 2) into a high-level sedimentation tank together to obtain the gray-water mixture and fly ash suspended on the water surface for subsequent use;

4) Put the ash-water mixture obtained in step 3) into the slag yard, and wait for the ash-water to separate naturally to obtain fly ash for subsequent use;

5) Airing the fly ash in step 2), step 3) and step 4) until the moisture content in the fly ash is ≤8%;

6) Add the fly ash in step 5 into the boiler according to the ratio of 6%, and carry out mixed combustion.

In step 5), the water content of the air-dried fly ash is tested, and the fly ash with a water content > 8% is air-dried again.

The fly ash is unburned or incompletely burned fly ash.

The addition of 6% fly ash in coal combustion is based on a series of tests. The process and conclusions of the tests are as follows:

Before the test, the fly ash was spread out and exposed to the sun, and the test was carried out after sampling and analysis of the moisture content of the fly ash below 8%. The data before the test were based on the data analyzed by the technical supervision department, and the data after the test were based on the coal transportation electronic scale and steam flow meter The measurement shall prevail. In order to reduce the error, the fly ash and coal are prepared by the precise measurement method of pulling coal and fly ash to the weighing room for weighing.

During data collection, in order to characterize the impact of fly ash on boiler operation, the furnace temperature was collected for tracking and comparison, because this parameter is a reflection of the normal operation of the boiler and is also the main parameter to characterize the thermal efficiency of the boiler. The furnace temperature directly determines the The steam-to-coal ratio, steam-to-electricity ratio, and steam production of boiler-related operating parameters are high and low; in addition, during the test, the coal is the same batch to eliminate the influence of different coal on the test, and the production load is basically the same, and the data sampling interval Shorter and comparable.

In order to theoretically calculate and analyze the coal ash-mixed samples after adding fly ash, the coal samples, fly ash samples, and coal ash mixed samples of different proportions were randomly sampled for laboratory analysis, and the following table was obtained:

It can be seen from the table that after mixing different proportions of fly ash, the detection index of the coal ash sample does not change much, which is suitable for boiler combustion. On the basis of the same operating mode, the addition test was carried out from the proportion of 3%, and then 4%, 5%, 6% and 7% of fly ash were added to carry out the combustion test. From the perspective of the overall macroscopic situation, the addition of different The proportion of fly ash has a favorable effect on combustion, which not only ensures production, but also saves energy. After adding different proportions of fly ash, the temperature of the furnace is higher than that without adding fly ash under the same conditions, and the temperature difference between the front and back arches becomes smaller, and it moves in a direction that is conducive to combustion. The reduction of the front arch temperature and the increase of the rear arch temperature prove that the added fly ash improves the suspension combustion of the boiler, increases the flame length, and its combustion effect is remarkable. Track and observe the boiler furnace temperature under different loads with different fly ash mixing ratios, and finally draw the furnace temperature change curve, as shown in Figure 2. According to the furnace temperature, the optimal ratio of fly ash is finally determined to be 6 %.

The beneficial effect of the invention is that the recovery and reuse of fly ash has remarkable effects in improving boiler combustion, reducing pollution, saving energy and reducing consumption, and is easy to implement and has very good application value.

The above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto, and any change or replacement that is not thought of through creative work should be covered within the scope of protection of the present invention. Therefore, The protection scope of the present invention should be determined by the protection scope defined in the claims.

Claims (5)

1. A kind of fly ash, it is characterized in that: add in the burning coal according to the ratio of 6%. 2. The fly ash according to claim 1, characterized in that: the fly ash is unburned or incompletely burned fly ash. 3. A method for recovering and reusing fly ash, comprising the following steps: 1) Desulfurization and dust removal treatment is carried out on the flue gas after combustion in the boiler to obtain the ash-water mixture for subsequent use; 2) Carry out slag removal treatment on the ash after combustion in the boiler to obtain the ash-water mixture and fly ash suspended on the water surface, for subsequent use; 3) Put the gray-water mixture in step 1) and step 2) into a high-level sedimentation tank together to obtain the gray-water mixture and fly ash suspended on the water surface for subsequent use; 4) Put the ash-water mixture obtained in step 3) into the slag yard, and wait for the ash-water to separate naturally to obtain fly ash for subsequent use; 5) Airing the fly ash in step 2), step 3) and step 4) until the moisture content in the fly ash is ≤8%; 6) Add the fly ash in step 5 into the boiler according to the ratio of 6%, and carry out mixed combustion. 4. The processing method of fly ash recovery and reuse as claimed in claim 3, characterized in that: in step 5), the moisture content of the fly ash after drying treatment is detected, and the fly ash with a water content > 8% is Carry out drying treatment again. 5. The method for recovering and reusing fly ash according to claim 3 or 4, characterized in that: the fly ash is unburned or incompletely burned fly ash.