Tianli Magnet Technology

1.1 definition

The current "Control Standards for Pollutants from Domestic Waste Incineration" stipulates that the start-up process of the domestic waste incinerator starts from the input of domestic waste until the rated incineration capacity is reached; the shutdown process of the domestic waste incinerator starts from the stop of the input of domestic waste until the remaining Domestic garbage is completely burned.

1.2 Current Reference Judgment Method

The current judgment basis for the start-up and shutdown status corresponding to the pollutant emission automatic monitoring data of domestic waste incineration power plants, mainly refer to the "Technical Specification for Continuous Monitoring of Fixed Pollution Source Flue Gas (SO2, NOx, Particulate Matter) Emissions", that is, through domestic waste The flue gas at the end of the incinerator flue gas purification facility online monitors oxygen, flow rate, flue temperature and other data for auxiliary judgment.

1.2.1 Determination of oxygen content

Judging from the online monitoring oxygen content data of the flue gas at the end of the domestic waste incinerator flue gas purification facility: the oxygen content gradually rises from the normal operating value (<19%) of the domestic waste incinerator, and when the value is >19%, it is judged to be shutdown Status: The oxygen content gradually decreases from the stop operating value (>19%) of the domestic waste incinerator, and when the value is <19%, it is judged to be the state of starting the furnace.

1.2.2 Flow rate determination

According to the data of on-line monitoring of the flue gas flow rate at the end of the flue gas purification facility of the domestic waste incinerator: the flow rate gradually decreases from the normal operating value of the domestic waste incinerator (>2m/s), and when the value is <2m/s, it is judged as the shutdown state ; The flow rate gradually rises from the stop operating value (<2m/s) of the domestic waste incinerator, and when the value is >2m/s, it is judged as the starting state.

1.2.3 Determination of smoke temperature

Judging from the online monitoring temperature data of flue gas at the end of the flue gas purification facility of the domestic waste incinerator: the flue gas temperature gradually decreases from the normal operating value of the domestic waste incinerator (>40℃), and when the value is <40℃, it is judged as the shutdown state; The flue gas temperature gradually rises from the stop operating value (<40°C) of the domestic waste incinerator, and when the value is >40°C, it is judged to be the state of starting the furnace.

1.2.4 Manual judgment

According to the actual operating experience of the operating personnel of the domestic waste incineration power plant, the status of the start and stop of the domestic waste incinerator is manually determined.

(1) The flue gas purification facility belongs to the auxiliary process facility of the domestic waste incinerator, and the online flue gas monitoring data at the end of the flue gas purification facility only reflects the flue gas emission status. Only the oxygen, flow rate, temperature and other data of the flue gas online monitoring at the end of the flue gas purification facility cannot accurately reflect the start and stop status of the domestic waste incinerator.

(2) The start-up and shutdown of the domestic waste incinerator belong to an operating process. The current reference judgment method has not yet clearly defined the start and end points of the start-up and shutdown process, and only indicates the switching point of the operating state.

(3) At the initial stage when the domestic waste incinerator is switched to the stop state, affected by the residual heat in the flue gas pipeline, the flue gas online monitoring temperature at the end of the flue gas purification facility is easily maintained at >40℃, especially when the summer environmental temperature in southern my country is high .

(4) The flue gas from the domestic waste incinerator is lifted and discharged through the chimney, and the chimney is naturally drawn. When the domestic waste incinerator is switched to the stop state, the flue gas online monitoring flow rate data at the end of the flue gas purification facility is susceptible to the natural pull of the chimney.

(5) The "Control Standards for Pollutants from Domestic Waste Incineration" stipulates that during the start-up and shutdown of domestic waste incineration plants, pollutants will be discharged stably within 4 hours, which cannot be accurately defined for the time being.

(6) There are errors in manual judgment. There are differences in the personal experience and cognition level of the operating personnel of the domestic waste incineration plants, and there is a deviation in the process of starting and stopping the furnace, and there is a risk of environmental protection responsibility in manual judgment.

3.1 Calculated temperature of domestic waste incineration furnace

The "Control Standards for Pollutants from Domestic Waste Incineration" stipulates that during the start-up process of the domestic waste incinerator, the calculated furnace temperature (850℃, 2s) must be charged at >850℃; during the shutdown process of the domestic waste incinerator, the furnace must be burned out The calculated temperature (850°C, 2s) must also be >850°C. It can be seen that during the start-up and shutdown of the domestic waste incinerator, the calculated furnace temperature (850°C, 2s) is one of the important criteria for determination.

In the actual operation process of a domestic waste incineration power plant, the calculated furnace temperature (850℃, 2s) change curve is an important basis for judging the operating state (see Figure 1).

"Notice on the installation of automatic pollutant emission monitoring equipment and networking related matters in domestic waste incinerators" stipulates that if the domestic waste incinerator has no furnace calculation temperature (850℃, 2s), the domestic waste incinerator connected to the national environmental protection monitoring platform can be used The arithmetic mean value of the three furnace temperature values in the middle and upper part of the furnace is replaced.

3.2 The feed door switch of the domestic waste incinerator

According to the actual operation of the domestic waste incinerator, the starting point for the start-up process of the domestic waste incinerator is to put domestic waste into the domestic waste incinerator, which can be judged by the first opening signal of the feed door of the domestic waste incinerator.

However, at present, some domestic waste incineration power plants often use domestic waste to physically seal the downcoming section of the feed inlet of the domestic waste incinerator during the drying stage. This is to prevent the front end of the furnace from being burned by heat, and on the other hand, to prevent the leakage of cold air in the furnace due to the inadequate closing of the feed door, which affects the furnace heating efficiency. Before the current operation mode of the domestic waste incineration power plants in the drying stage is adjusted, the signal for the first opening of the feed door of the domestic waste incinerator cannot be used as the basis for determining the starting point of the start-up process of the domestic waste incinerator.

During the shutdown process of the domestic waste incinerator, the termination point is that the domestic waste incinerator stops inputting domestic waste, which can be judged by the closing signal of the feed door of the domestic waste incinerator.

3.3 Actions of domestic waste incineration grate

According to the existing typical domestic waste incinerator type, the grate in the furnace is divided into a drying section, a burning section, and a burnout section (see Figure 2). After the domestic waste enters the grate of the furnace drying section from the feed inlet, the start-up process of incineration of domestic waste begins. The grate of the drying section must be activated to promote the incineration of domestic waste evenly. However, some domestic waste incineration power plants will try to start the grate at the oven stage to verify whether the grate can operate normally.

3.4 Boiler main steam valve switch

During the actual operation of the domestic waste incineration power plant, the domestic waste incinerator completes the start-up process. After the operation reaches a stable state, the main steam valve of the boiler opens to supply steam to the steam turbine side to promote the operation of the steam turbine and generator set to generate electricity.

At present, most domestic waste incineration power plants are equipped with steam turbines and generator sets. In the actual operation process, the putting into operation of the steam turbine and the generator set has become one of the important signs of the normal and stable operation of the domestic waste incineration plant.

3.5 Start and stop of auxiliary combustion system of domestic waste incinerator

The auxiliary combustion system of the domestic waste incinerator is one of the important equipment to assist the stable incineration of domestic waste in the furnace during the start-up and shutdown of the domestic waste incinerator. The auxiliary combustion raw materials are mainly zero diesel or natural gas.

According to the actual operating experience of more than 10 domestic waste incineration power plants, in the start-up process of domestic waste incinerators, in order to ensure that the calculated furnace temperature (850°C, 2s) ≥850°C, the auxiliary combustion system must be activated from the time the domestic waste is put into life. After the garbage combustion is stable, stop the auxiliary combustion system. During the shutdown process of the domestic waste incinerator, in order to ensure that the calculated temperature of the furnace (850℃, 2s)≥850℃, the auxiliary combustion system must be started from the stop of the domestic waste input. After the remaining domestic waste in the furnace is completely burned, the auxiliary combustion system must be stopped. .

4 Judgment suggestions

Based on the above analysis of key factors in the start-up and shutdown of the domestic waste incinerator and the existing problems in the judgment basis of each domestic waste incineration power plant, combined with the actual operation of each domestic waste incineration power plant, the recommended judgment basis is as follows.

4.1 Judgment basis for the start-up process

(1) When the domestic waste incinerator meets the following conditions at the same time, it is judged as the starting point of the start-up process:

① The calculated temperature (850℃, 2s) of the furnace chamber of the domestic waste incinerator is >850℃ for the first time.

② On-line monitoring of the flue gas at the end of the flue gas purification facility is normal, and the oxygen content value is <19%.

③ The inlet door of the domestic waste incinerator is opened for the first time.

④ After the domestic waste incinerator is shut down, the grate in the drying section of the furnace moves for the first time.

(2) When the domestic waste incinerator meets the following conditions at the same time, it is judged as the end of the start-up process:

① The auxiliary combustion system in the furnace of the domestic waste incinerator stops operating.

② The calculated temperature of the furnace chamber of the domestic waste incinerator (850℃, 2s) or the arithmetic average of the three furnace temperatures in the middle and upper part of the furnace of the domestic waste incinerator networked with the national environmental protection monitoring platform> 850℃ and lasts for 10 minutes.

③ On-line monitoring of the flue gas at the end of the flue gas purification facility is normal, and the oxygen content is >19%.

④ The main steam door of the boiler is opened, and the steam turbine and generator set are started.

4.2 Judgment basis for shutdown process

(1) When the domestic waste incinerator meets the following conditions at the same time, it is judged as the starting point of the shutdown process:

① The auxiliary combustion system in the furnace of the domestic waste incinerator is activated.

② The feed door of the domestic waste incinerator is closed.

(2) When the domestic waste incinerator meets the following conditions at the same time, it is judged as the end of the shutdown process:

① The auxiliary combustion system in the furnace of the domestic waste incinerator stops operating.

② The calculated temperature of the furnace chamber of the domestic waste incinerator (850°C, 2s) or the arithmetic average of the three furnace temperatures in the middle and upper part of the chamber of the domestic waste incinerator connected to the national environmental protection monitoring platform <850°C.

③ On-line monitoring of the flue gas at the end of the flue gas purification facility is normal, and the oxygen content is >19%.

5 Conclusion

In the future, as domestic waste incineration becomes the mainstream industrialization technology for domestic waste treatment in my country, public attention continues to increase, and related environmental protection supervision work is bound to become increasingly severe. As an environmental protection enterprise, domestic waste incineration power plants must keep up with the pace of the times, strictly follow the requirements of automatic pollutant discharge monitoring data networking, standardize operation procedures, improve standardized operation levels, and fulfill the main responsibility of the company's environmental protection.