How to effectively reduce the low NOx produced during oilfield steam boiler combustion?
Background technology
As the main production position at the present stage of oilfield production, heavy oil thermal recovery plays a key role in the stable supply of crude oil in China. Steam injection boiler, the key equipment of heavy oil thermal recovery, is not only an important guarantee for heavy oil production.
With the continuous strengthening of environmental requirements, protecting water resources and controlling air pollution have become the key points restricting heavy oil production. How to achieve environmental protection and provide energy for heavy oil production has become the key research direction of heavy oil production technology. It is very important and urgent to study the steam injection boiler with low flue gas emission.
From 2013 to 2014, the technical testing center conducted a flue gas index test on 16 steam injection boilers in use, including 6 sets of crude oil, 8 sets of fuel oil (residue), and 2 sets of natural gas. From the test results, the flue gas discharged by burning natural gas can basically meet the standard, while others can not meet the standard.
According to the formation mechanism of nitrogen oxides, nitrogen compounds in the flue gas are mainly divided into thermal type, fuel type and fast type NOx, of which the generation amount of fast type NOx is very small and can be ignored. Thermal NOx means that when the furnace temperature is above 1350 ℃, nitrogen in the air is oxidized to generate NOx at high temperatures.
When the temperature is high enough, thermal NOx can reach 20%. Fuel type NOx refers to the NOx generated by the organic nitrides in the fuel during combustion, and its amount mainly depends on the mixing ratio of air and fuel. Fuel type NOx accounts for about 75% ~ 90% of the total NOx generation.
SanJack company provides a low NOx steam injection boiler combustion device aiming at the above defects in the prior art.
The technical scheme comprises a boiler, a burner, a primary air inlet pipe, an emulsifier, a water inlet pipe, a fuel pipe, a secondary air inlet pipe, a fixed frame, a gas transmission pipe, a flue gas return pipe, an automatic regulating valve and a low-carbon flue gas output pipe. The outside of the boiler is connected with the burner, the outside of the burner is connected with the primary air inlet pipe, and the bottom of the burner is connected with the emulsifier, The emulsifier is connected with the water inlet pipe and the fuel pipe, the burner is connected with the gas chamber inside the boiler, the top outlet of the boiler is provided with a low-carbon flue gas output pipe, the low-carbon flue gas output pipe is provided with a flue gas control valve, the automatic regulating valve and the flue gas control valve are connected with a PLC controller, a flue gas return pipe is arranged between the boiler and the burner, and the secondary air inlet pipe and the flue gas return pipe are provided with an automatic flue gas regulating valve, The outside of the boiler is connected with a secondary air inlet pipe, and the secondary air inlet pipe is connected with a gas chamber through a gas transmission pipe.
The gas transmission pipe is fixed on the shell of the boiler through a fixing frame, and the horizontal included angle a between the gas transmission pipe and the boiler is 90-150 degrees.
The automatic flue gas regulating valve comprises a valve body, an air inlet, an air outlet, a valve seat, a valve core, a valve rod, a bellows, a spring, a valve cavity and an adjusting block. The two ends of the valve body are provided with an air inlet and an air outlet, the lower part of the valve body is provided with a valve cavity, and the middle of the valve body is provided with a valve seat.
The valve core is fixed on the valve seat, the lower part of the valve core is connected with the valve rod, the valve rod is arranged inside the valve cavity, and the valve rod is connected with a bellows The outside of the bellows is provided with a spring, the upper part of the spring is provided with an adjusting block, the adjusting block is matched with the inner side of the valve cavity, and a back pressure channel is arranged between the valve cavity and the air outlet.
The beneficial effects of this unit are: the emulsifier can emulsify the fuel oil, the emulsified fuel oil produces a “micro explosion” effect in the combustion process, can improve the combustion process, the vaporization and heat absorption of water in the emulsified fuel reduces the working medium temperature and the maximum combustion temperature, significantly reduces the thermal cracking reaction of the fuel oil and inhibits the formation of soot. According to the measured flame temperature, the PLC controller, The automatic air regulating valve in the secondary air duct is automatically adjusted to control the input of secondary air, which can effectively improve the combustion in the second half of the flame, ensure the complete combustion of fuel and ensure the combustion efficiency under the condition of less NOx generation.
2.burner
3.primary air inlet pipe
4.emulsifier
5.water inlet pipe
6.fuel oil pipe
7.secondary air inlet pipe
8.fixed frame
9.gas transmission pipe
- flue gas return pipe
- automatic control valve
12.low carbon flue gas output pipe
- flue gas control valve
14.PLC controller
