How to improve 5000t/d new dry cement production line to reduce nitrogen and oxygen compounds

Date: 2019-09-03 Views:

With the increasingly strict environmental protection situation, the emission limits of nitrogen and oxygen compounds are also more stringent.Increasing technological innovation and introducing new technologies will be the only way out for environmental protection and cost reduction in cement industry.Below, the application experience of low nitrogen burner in 5000t/d new dry cement production line is Shared with you.
 

1. Application background


A cement co., LTD. (hereinafter referred to as "company") 5000 t/d NSP cement production line use Φ 5.0 x 68 m rotary kiln, RF5/5000 preheater with decomposition furnace system.After completion, there has been a problem of high energy consumption in similar kilns, and the online monitoring system shows that the emission value of nitrogen and oxygen compounds is high, which cannot meet the current standard requirements.Therefore, we conducted thermal calibration and analysis of the system, and the results showed that the burner configured by the system had a series of problems, such as high primary air volume and large pipe diameter, which required necessary technical transformation, and decided to replace the new low-nitrogen coal saving burner.
 

2. Principle of action


At present, the domestic production of low-nitrogen coal burner is mainly through the control of the primary air into the kiln, the traditional burner "large thrust" wind characteristics changed to "relatively high momentum" principle.That is to say, the use of "high wind speed, low air volume" to inhibit the formation of nitrogen oxides.
 

3. Transformation process

 

We chose the most suitable low-nitrogen burner, and djgx-530b was selected as the model of kiln burner.Djgx-5000t /d is selected as the burner model of the decomposition furnace.Specific technical parameters of kiln head and burner of decomposition furnace are modified as follows:


(1) kiln head coal feeding fan: the flow is changed from 76m3/min to 45m3/min;The pressure was changed from 68.6kpa to 49kpa;The power is changed from 132kw to 55kw.

(2) kiln head net fan: flow rate changed from 161m3/min to 70m3/min;The pressure was changed from 29.4kpa to 49kpa;Power 110kw unchanged.

(3) the kiln head will send coal pipeline by ф ф 194 mm 273 mm instead, on the premise of meet the stable delivery to ensure higher pulverized coal injection rate.

(4) coal feeding fan at the end of kiln: the flow rate is changed from 114m cubed /min to 70m cubed /min;The pressure was changed from 68.6kpa to 45kpa;The power is changed from 185kw to 75kw.

(5) to coal pipe preheater: main line to ф ф 377 mm 273 mm;In charge of the way by to ф ф 299 mm to 203 mm.

(6) the original decomposition furnace single tube coal injection into a swirl burner, to ensure the rapid diffusion of pulverized coal, uniform mixing, improve the combustion efficiency.

cement production line

4. Application adjustment


After the transformation we carried out industrial tests.Due to the high moisture content of Mongolian coal used before, the average moisture content of pulverized coal is about 6%.In this way, the preheating time of pulverized coal ignition is long, and the heat absorption of steam vaporization has a great influence on the heat intensity of calcining.Therefore, the net wind accounts for 5.1% of the total kiln wind, the coal wind accounts for 2.9%, and the total primary wind is 8%.After the increase of the net wind speed, the hot flue gas backflow can be formed, the fire temperature can be increased, and the preheating time can be shortened effectively.
 

5. Application effect


Through the above modification and adjustment, the kiln system runs stably and its quality is qualified.Clinker granulation are uniform compact, good color, no yellow core material.Before and after the transformation, the output of kiln platform increased by 5t/h year on year, which is equivalent to about 40,000 tons of clinker produced by a single line every year, achieving a net profit of about 3.2 million yuan.Clinker coal consumption decreased by 2.5kg/t year on year, equivalent to 4,365 tons of coal saved every year. If the coal price is calculated at 600 yuan/ton, the annual capital saving is 2.62 million yuan.The comprehensive power consumption of clinker decreased by 2.1 degrees/ton year on year, saving about 830,000 yuan per year.It can be seen that the three comprehensive production lines of clinker with a daily output of 5,000 tons can save 6.65 million yuan per year, and the energy saving and economic benefits are very significant.At the same time, after the use of low nitrogen saving coal burner, the nitrogen oxide emission value decreases to about 318mg/m3, and the sales effect is also very obvious, which can reduce the thermal NO2 emission by more than 20%.
 

6. Application conclusion


It can be seen that the application of low nitrogen coal saving burner in new dry cement production line is successful, which is a new starting point for cement enterprises to reduce cost and increase efficiency.It has achieved a win-win situation of social and economic benefits and is in line with the relevant industrial policies of national energy conservation and emission reduction.However, it is necessary to make technical adjustment according to the actual conditions of the enterprise, such as process configuration, quality and characteristics of pulverized coal, so as to achieve the expected effect.

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