Heat preservation and application of heating pipe in flue gas denitrification system
The flue gas denitrification system of a thermal power plant is an important environmental treatment facility in the power generation system The stability of the denitrification system has a great impact on the protection of the atmospheric environment in the adjacent area. The urea hydrolysis ammonia production system includes a urea dissolution tank, a urea solution pump, a urea solution storage tank, a feed pump, a hydrolyser, an ammonia buffer tank, and other equipment. The urea solution in the hydrolyser is hydrolyzed to ammonia, carbon dioxide, and water vapor under specified conditions such as temperature, pressure, and residence time, and after pressure adjustment is transported to the ammonia buffer tank. However, during the operation of the ultra-pure system, the operation of the denitrification system was unstable, ammonia gas carried water seriously, and the reaction efficiency of the denitrification catalyst was low, causing resistance to environmental management.
Take as an example a thermal power plant in Anyang, Henan Province. After analysis, the main reasons for the unstable operation of the station denitrification system, the low efficiency of the ammonia gas water reaction, and the low efficiency of the denitrification catalyst reaction are: the original device product gas pipeline is long, the pipeline is poor heat insulation and heating effect, which causes the product gas temperature to drop excessively, In addition, the volume of the product gas is very high. And the temperature of the product gas below the dew temperature Hidden danger of the mixed ammonia-air gas pipeline corrosion After the ammonia mixer with air in the SCR zone, the water contact in the pipeline with the ash carried by the secondary air will cause an accumulation that will affect the denitrification efficiency of the flue gases and lead to instability of the emission of nitrogen oxides in the flue gases.
When analyzing causes, the main cause of pipeline blockage and poor denitrification effect is poor heat preservation and pipeline heating effect. Thus, the conversion goal can only be achieved by selecting the best heat preservation method and heating method to further improve the heat preservation and heating effect of the pipeline. In recent years, there are three main methods for heating a steam forecastle, heating pipes with a steam jacket and electric heating in the transportation of gaseous products of a urea and ammonia hydrolysis plant.
After many comparisons, the energy company finally opted for our composite heating and sampling pipe.
After the plant reformed the thermal insulation and heating of the product gas pipeline of the urea hydrolysis ammonia production system, it completely eliminated the hidden danger of condensate blockage caused by the long pipeline and poor thermal insulation and heating effect, improved the stability of the denitrification system operation, and reduced nitrogen oxide emissions in flue gases.
Electric heating cable is a heating method that uses insulation resistance or resistance heating wire to create a temperature after power supply. It can automatically adjust the output temperature and reasonably maintain the process temperature requirements to keep warm, raise the temperature and protect the heating equipment from freezing. The insulation and antifreeze effect of the container is very good.
Transport of heavy oil through the pipeline over long distances and long-term retention in the pipeline will result in a drop in temperature due to heat dissipation and increased viscosity, which will cause the pipeline to be blocked by freezing or condensation-related accidents. Electric heating is widely used as effective insulation of pipelines and anti-freeze protection.
According to the statistics of the Hydrometeorological Center, the average daily minimum temperature at the location of the CNPC tank farm is 5 ° C, and the average daily maximum temperature is 14 ° C. Since the freezing point of the PX is about 15 °C, the supply pipeline needs heat preservation and heating. The oil depot has been in operation for many years without a stable source of steam, therefore, this project is considering the use of electric heating technology.
Long-distance crude oil pipelines with a high paraffin content with freezing temperatures above 50 °C. According to the requirements of the production plan of the plant, the volume of oil transportation through the pipeline is 150 thousand rubles. Tons per year, maximum-200 thousand. Tons per year.. According to the thermodynamic analysis of the pipeline, the initial supply temperature of the pipeline is 80 ° C (TN), and the temperature of the end entering the tank is 60 ° C (Tu). Since the transportation temperature needs to be adjusted according to the time of year, it sometimes needs to be transported by heat.
In petrochemical engineering, trunk infusion pipelines are the lifeblood of the factories. The temperature in the northern region is too low in winter and the pipeline needs to be insulated to compensate for the heat loss due to the low temperature in winter to ensure the normal operation of the pipeline.
The toughness of the asphalt is greatly affected by the temperature. When the temperature decreases, the toughness of the asphalt increases, and the drop in resistance of the asphalt during pipeline transportation increases; when the temperature falls below the freezing point, the asphalt solidifies, causing the pipeline to clog and the conveyor belt to come to trouble. Therefore, electric heating and heat preservation during the transportation of asphalt are very important.
To solve many problems in the "three high levels" crude oil extraction process, the thermal energy generated by the electric heating is used to heat the crude oil in the oil pipe throughout the process to improve the fluidity of the crude oil. Effectively solve various technical problems encountered in the operation of high-condensation, high-viscosity and high-paraffin crude oil, and achieve the goal of improving the productivity and efficiency of oil wells.