In the heat (pump) station of the oil pipeline, the influence of the exhaust and soot blowing of the heating furnace on the environment is becoming more and more serious, which causes the heating furnace to fail to blow the ash on time, so that the ash accumulation in the heating furnace increases, the efficiency decreases, the fuel oil consumption increases, and the furnace tube corrodes. Serious, the furnace life is reduced, the safety of use is reduced. In view of the above problems, through the analysis of the current situation of the heating furnaces of each oil heat (pump) station, the flue gas dedusting system is used to purify and filter the harmful medium of the flue gas to achieve the purpose of purifying the flue gas.

1 Introduction

Hot oil delivery pipelines are widely used to heat crude oil in a fuel heating furnace. In order to keep the furnace stable and efficient, soot blowing is an effective measure. The soot blown used in the heating furnace is used to remove the ash from the convection chamber tube, and the blown ash is discharged from the furnace chimney. The heavier particles are scattered in the station area and the farmland, and the lighter flue gas components are mixed into the atmosphere, resulting in The pollution of the station area and the surrounding environment has become a prominent environmental pollution problem in the process of crude oil transportation, and it is also one of the few disturbance problems of crude oil transportation stations.

2. The necessity of system setting

2.1 Meet the requirements of environmental protection for furnace flue gas emissions

When the furnace is in normal operation, the dust emitted is very small, not exceeding 250mg/m3, and the Ringermann blackness is less than level 1, which has little impact on the surrounding environment and can meet the requirements of environmental protection regulations. However, during the soot blowing operation of the heating furnace, the fluctuation of the concentration of the soot in the heating furnace is large, the average concentration of the soot can reach 2500 mg/m3, and the Ringermann blackness is about 3, which has a great impact on the environment, far exceeding the Environmental regulations. As one of the local atmospheric pollution sources, heating stations of various oil stations have always been the focus of local environmental protection departments. With the increase of the government's environmental protection policies, the contradictions have become increasingly intensified. The stations in the oil transportation stations often receive the penalty orders from the environmental protection departments, so that the stations cannot perform the soot blowing operations according to the normal soot blowing time.

By adding a flue gas dedusting system, high-efficiency dust removal can be carried out during the soot blowing operation period of the furnace, and the dust purification efficiency can be as high as 99%, effectively reducing the emission of soot and meeting the requirements of environmental protection for the flue gas emission of the heating furnace.

2.2 can effectively reduce the corrosion of soot to the furnace tube and improve the operation safety of the furnace

Due to the influence of the local environmental protection department on the rectification of the soot blowing operation of the heating furnace and the interference of the local people on the soot blowing operation of the heating furnace, the soot blowing operation of each station cannot be completed in time and according to the operation regulations, so that the furnace tube is accumulated. There are more and more ash, and the ash contains more corrosive components, which inevitably cause corrosive damage to the furnace tube. Furnace tube corrosion not only greatly reduces the service life of the furnace, but also brings the safety hazard of the furnace operation. Long-term operation may cause the furnace safety accident, and increase the safety maintenance cost and cleaning cost during operation. By adding a flue gas dedusting system, the soot emission from the soot blowing operation of the heating furnace meets the national and local requirements, so that the soot blowing operation can be carried out normally, which can effectively reduce the corrosion of the furnace tube by the soot, increase the service life of the heating furnace, and improve the heating. The safety of the furnace operation.

2.3 can improve the heating efficiency of the furnace and reduce the fuel consumption

The actual operation shows that due to the long-term failure to carry out the soot blowing operation as required, a large amount of soot is accumulated on the furnace tube, which reduces the heat transfer efficiency and greatly affects the heating efficiency of the heating furnace. Mainly reflected in the two aspects of significantly increased exhaust gas temperature and fuel oil consumption.

Under normal circumstances, the exhaust temperature of the heating furnace is between 160 ° C and 180 ° C. However, due to the soot of the furnace tube, the exhaust gas temperature is often higher than 200 ° C, even up to 300 ° C.

Due to the accumulation of soot in the furnace tube, the heat transfer efficiency of the furnace tube is reduced, and the fuel oil consumption is bound to increase under the premise of meeting the heating temperature requirement. The practice results show that the fuel oil consumption before the furnace tube cleaning is significantly more than after the cleaning. By adding a flue gas dedusting system, the soot blowing operation can be carried out normally, which can effectively reduce the accumulated dust on the furnace tube, improve the heat transfer efficiency of the furnace tube, and reduce the fuel oil consumption.

3. System principle

According to the number and type of heating furnaces installed in the station, the dust removal system with different treatment capacity is designed and designed, and a set of flue gas dust removal treatment facilities is shared with all the heating furnaces at the same station, and the corresponding processing equipment is carried out according to the maximum furnace type. Normally processing the flue gas of a furnace, if encountering multiple furnaces running at the same time, it can be carried out by staggering the soot blowing time period of the furnace, and simultaneously switching the flue valves to separately treat the dusty flue gas during soot blowing. Reduce dust emissions. The dust removal system adopts an automatic control system, which can automatically complete soot blowing and dust removal according to the soot blowing command.

Working principle of flue gas dedusting system: cyclone dust removal + bag dust collector integrated process. Its main equipment includes: cyclone dust collector, bag filter, fan, silo pump and ash silo.

The process is as follows:

Before starting the soot blowing system, first turn on the fan, flue valve and fill air valve. When the heating furnace reaches the normal combustion condition when the fan is guided, the soot blowing command is issued to carry out the soot blowing operation. The dusty flue gas first enters the cyclone dust collector for large particles. The collection and treatment of the soot, the flue gas containing the fine particles enters the bag filter, and the clean flue gas filtered through the bag is discharged into the atmosphere by the fan. After the end of the soot blowing, the dust removal treatment system is turned off for a delay, the corresponding valve is switched, and the heating furnace is used for normal combustion operation.

The dust collected by the dust removal system is collected in the ash bin at the lower part of the cyclone and the bag filter. The dust is regularly sent to the silo pump from the cyclone discharge of the cyclone and the bag filter by the dust control command issued by the control computer, and the pneumatic conveying method is adopted. It is sent to the ash warehouse and is regularly shipped by the contract unit.

4. Analysis of fuel consumption before and after the flue gas dedusting system

According to experience, if the temperature of the exhaust gas of the heating furnace is increased by 12 ° C to 15 ° C, the efficiency of the heating furnace will be reduced by 1%, and the fuel oil consumption will increase by more than 1% of the original consumption. Taking the 8000kW, 5000kW and 2500kW direct heating furnaces commonly used in actual operation as an example, the fuel consumption before and after the exhaust gas temperature rise is compared.

Taking the operating parameters as the working condition before the soot blowing in the heating furnace, the design parameters are approximated to the working condition after the soot blowing in the heating furnace. The fuel consumption per ton of fuel oil is 3,500 yuan, then the above three heating furnaces will save fuel after soot blowing. The cost is about 217 yuan / h, 95 yuan / h and 53 yuan / h, the energy saving effect is obvious.

5. Analysis conclusion

From the test results, the controllability and operational reliability of the system are good, which basically meets the requirements of the enterprise, and meets the various economic and technical indicators proposed by the design. By adding a flue gas dedusting system, it effectively reduces the generation of soot blowing in the heating furnace. The dust removal efficiency can reach more than 95%. It improves the service life and safety of the furnace, and reduces the corrosive damage caused by fuel consumption and soot accumulation on the furnace tube. Therefore, the flue gas dedusting system is suitable for application and promotion in a fuel heating furnace of a heat transfer pipeline station.

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