In recent years, some areas have realized the transition from coal-fired boilers to gas-fired boilers in the use of boilers. Industrial boilers or heating boilers in many cities have been replaced by gas-fired boilers with relatively energy-saving and environmental protection. At the national policy level, we also strongly support the "coal-to-gas" transformation of boilers. It can be said that, based on the advantages of gas boiler in environmental protection, energy saving and consumption reduction, it has been widely recognized in the process of popularization and use. In terms of volume, gas-fired boilers are much smaller than coal-fired boilers, and they can be used more efficiently in the process of boiler operation. In reality, gas-fired boilers have a wide range of applications and good market prospects. With the development of technology, the control system of gas-fired boiler is becoming more automatic and intelligent.
Key Points of Energy-saving Operation Control for Gas-fired Boilers
1. Accurate and scientific control of air
Under the standard state of air coefficient, the theoretical air volume of 1 cubic meter gas fuel, which is called the theoretical air volume of gas fuel, is expressed in v0. In the actual working process, according to the composition of gas fuel, we can calculate the air quantity V into the boiler, which is called the actual air quantity. The value expressed by V is larger than the theoretical air quantity from the practical experience. Among them, the part of air which is more than the theoretical air quantity is the excess air. So we can know that the actual air volume is the sum of theoretical air volume and excess air volume. The ratio of actual air volume to theoretical air volume is called excess air coefficient, which is expressed by alpha, i.e. alpha=v/v0. From the point of view of technical control, excess air coefficient alpha has a very important influence on combustion efficiency and actual operation of gas-fired boilers. Specifically, if the value of alpha is too small, the natural gas in the gas-fired boiler can not be fully burned, resulting in a part of the waste of natural gas.
2. Reasonable control of outlet water temperature of gas-fired boilers
During the actual operation of gas-fired boilers, the heating situation will change constantly. When the weather changes, the total heat demand in the heating zone of the boilers will change accordingly. In a day, the heat demand of day and night is also different, which requires gas-fired boilers to adjust the gas and air conveyance scientifically and reasonably according to the change of total heat demand at all times in order to ensure the operation efficiency of the boilers, not only to ensure the necessary heat demand supply, but also not to.
Waste gas resources. At present, there are many low nitrogen burners with electronic proportional control. For this kind of burner, the outlet water temperature is mainly controlled by single-loop PID. On this basis, according to the difference between the set value of outlet water temperature and the measured value of actual outlet water temperature, the fuel valve is adjusted to make it more reasonable gradually. The state of being. In this process, in order to achieve the best combustion effect, the oxygen content of flue gas can also be directly increased, thus ensuring sufficient oxygen in the air.
3. Reasonable control of oxygen content in flue gas
From the actual situation, when the boiler burns, reasonable control of oxygen content in flue gas can also reduce the waste of fuel to a certain extent. In technology, a control loop is added to the combustion control system. The main function of this control loop is to control the variable ratio of combustion flow and air flow. This control system is also called closed-loop control system of oxygen content in flue gas. By using this control system, the boiler can ensure the most economical combustion in the whole production process. From the actual situation at this stage, the more commonly used is the oxygen content in flue gas. Therefore, it can be said that in the process of boiler combustion, the reasonable control of oxygen content in flue gas can be further improved by adding control loops. This method is relatively simple and economical. The control of oxygen content in flue gas should be combined with the actual operation status of the ignited boiler. Under different operating conditions, the ratio of oxygen content in flue gas should be adjusted reasonably so as to meet the needs of boiler combustion and reduce energy consumption as far as possible.
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