Waste heat boiler refers to a boiler that heats water to a certain temperature by using waste heat in waste gas, waste or waste liquid in various industrial processes and the heat generated by the combustion of combustible substances. Oil-fired boilers, gas-fired boilers , and coal-fired boilers with waste heat recovery and utilization of smoke boxes and flues are also called waste heat boilers. Waste heat boilers can produce hot water or steam for use in other sections through waste heat recovery .
working principle
Fuel, gas, and coal are burned to generate high-temperature flue gas to release heat. The high-temperature flue gas first enters the furnace, then enters the waste heat recovery device of the front smoke box, then enters the pyrotechnic pipe, and finally enters the waste heat recovery device in the flue of the rear smoke box. The flue gas becomes low-temperature flue gas and is discharged into the atmosphere through the chimney. Because the waste heat boiler greatly improves the utilization rate of the heat released by fuel combustion, this kind of boiler is very energy-saving.
Classification
Waste heat boilers are divided into fuel-fired waste heat boilers, gas-fired waste heat boilers, coal-fired waste heat boilers and foreign media waste heat boilers according to fuel. According to the use, it is divided into waste heat hot water boiler , waste heat steam boiler, waste heat organic heat carrier boiler, etc. Features
The high-temperature flue gas released by burning coal is transported to the inlet of the waste heat boiler through the flue, and then flows through the heater, evaporator and economizer, and finally is discharged into the atmosphere through the chimney. The heat released from the drop in temperature from the high temperature to the exhaust temperature is used to turn the water into steam. The boiler feed water first enters the economizer, and the water absorbs heat in the economizer and heats up to a temperature slightly lower than the saturation temperature under the pressure of the steam drum and enters the drum. After the water entering the drum is mixed with the saturated water in the drum, it enters the evaporator along the downpipe below the drum to absorb heat and start producing steam. Usually only a part of the water turns into steam, so the steam-water mixture flows in the evaporator. . The steam-water mixture leaves the evaporator and enters the upper drum and is separated by the steam-water separation equipment. The water falls into the water space in the drum and enters the descending pipe to continue to absorb heat and generate steam, while the steam enters the superheater from the upper part of the drum to absorb heat to turn saturated steam into superheated steam. . According to the three stages of the steam production process, there are three heating surfaces, namely the economizer, the evaporator and the superheater. If superheated steam is not required, only saturated steam is required, and the superheater may not be installed. When there is reheated steam, a reheater can be added.
Drum introduction
The drum is provided with pipe bases for pickling, thermal measurement, water level gauge, water supply, dosing, continuous sewage discharge, emergency water discharge, safety valve, air valve, etc., as well as manhole devices. There are two spring safety valves on the drum ; two water level gauges, which are quartz tube type two-color water level gauges, are safe and reliable , easy to observe and indicate correct. Sleeve-type sockets are used in the inlet pipe holes of the boiler drum and other pipe holes that may have a large temperature difference to prevent cracks due to thermal fatigue near the pipe holes. The internal device of the drum is provided with a separation device for separation of steam and water, as well as connecting pipes for boiler feed water and dosing. The drum is equipped with two supports, one is a fixed support and the other is a movable support.
flue
It consists of distribution header, lower header, tube group and upper header. The boiler feed water is led out from the drum and into the distribution header. In order to prevent the temperature deviation of each part of the header, the inlet water of the distribution header and the lower header is introduced by the dispersing downpipe, and the water enters the lower header and is dispersed into 132 φ42×4 The pitch circle composed of seamless steel pipe and 6mm thick flat steel is a circular flue heating surface with a diameter of 2400mm, and then a soda-water mixture is generated into the upper header, and introduced into the drum by the riser.
routine maintenance
1. Observe the water level with the water level meter, and repair the damaged water level meter in time;
2. If the pressure gauge is damaged or the dial is unclear, replace it in time;
3. Valves that run, run, drip, and leak can be repaired or replaced in time;
4. The thermal insulation layer and the reinforced inner lining are intact.
5. Each shift should regularly check the flexibility and working conditions of the transmission device, and lubricate it in time to ensure its normal operation;
6. Check and maintain fans, water supply pipeline valves , water supply pumps, etc.;
7. Check that all connecting pipe flanges and other parts of the boiler system must be tightly closed without air leakage;
8. If the induced draft fan vibrates violently, it should be stopped for inspection. Generally, it is caused by the wear of the internal impeller and should be replaced;
9. Water should not accumulate on the ground and heating pipes at the bottom of the boiler header to prevent moisture from corroding the base;
10. Regularly check the shaft end seal of the three-way flapper valve, the operation of the main shaft and the electric device, and troubleshoot in time;
11. Regularly check whether the boiler steam pressure, water level, superheated steam output and temperature are normal;
12. Check all foundation anchor bolts for looseness. It must be tightened , otherwise it will cause vibration;
13. The water level gauge must be flushed once per shift;
14. The manual steam or water release test of the safety valve is performed at least once a week , and the automatic steam or water release test is performed at least once every three months ;
15. The pressure gauge should be flushed once a week during normal operation, and the water trap should be calibrated at least once every six months ; a red line indicating the working pressure should be drawn on the dial, and lead-sealed after calibration;
16. High and low water level alarms, low water level interlocking devices, overpressure, overtemperature alarms, and overpressure interlocking devices shall be tested at least once a month;
17. The equipment maintenance and safety accessories test and calibration should be recorded in detail, and the boiler operation management personnel should conduct random inspections on a regular basis.
Scope of application
Through research, we know that waste heat utilization affects a wide range of industries, and is making progress in various fields of thermal energy utilization. Due to the different fields, the methods are different. From the research, not only a new understanding of the utilization of waste heat, but also many new waste heat utilization methods have been discovered.
For example , there are three main methods for the utilization of engine waste heat , namely, thermoelectric power generation, exhaust gas turbine power generation and Flon turbine power generation. Thermoelectric power generation mainly uses thermoelectric power generation materials to generate electricity. However, due to the low energy conversion rate of thermoelectric materials , it is necessary to develop thermoelectric exchange materials with high conversion rates. The exhaust gas turbine power generation is to use the exhaust gas to drive the turbine to drive the generator to generate electricity. This power generation method has a certain , and further research is required.
For example, the waste heat utilization of air conditioners is closely related to family life because air conditioners are installed indoors. Traditional air conditioners generally discharge the heat absorbed indoors through the outdoor unit, which not only produces a lot of greenhouse gases, but also wastes a lot of heat energy. The following introduces a method for processing hot water using the waste heat of central air conditioners. The steps are as follows:
Install a water separator in the high temperature area of the condenser of the central air conditioner, and the water separator contains 50% -100% of the condenser tubes in the high temperature area and forms an independent and closed heat exchange area;
Therefore, the state advocates vigorous development of waste heat utilization, energy conservation and emission reduction, which plays a positive role in protecting energy and improving the quality of human living environment. In the design of waste heat boiler, how to reasonably divide the temperature section is the basis for rationally arranging the heating surface of the waste heat boiler and maximizing Under the condition of a given waste heat boiler inlet flue gas temperature, there are two requirements for the exhaust gas temperature, one is to limit the exhaust gas temperature, and the exhaust gas temperature is required to be within a reasonable range; the other is to not limit the exhaust gas temperature, It is required to maximize the use of waste heat.
development trend
In recent years, with the sharp rise in the price of various energy sources, people have begun to focus on the operating cost of boilers. In reality, the production of enterprises cannot be separated from steam boilers. Without a hot water boiler, the fuel cost of the boiler is a very large expenditure. In order to avoid the objective phenomenon of "buying a boiler, but not using a boiler" as much as possible, savvy boiler manufacturers have carried out a series of energy-saving renovations for boilers. The main content of the renovation is the waste heat recovery of boilers. Customers of waste heat boilers appreciate their equipment.
In fact, energy saving is one of the key factors for a country 's sustainable development. If we still adhere to the traditional way of energy utilization and cannot make effective recycling of resources, it will aggravate the deterioration of the entire resource environment of the society, and cause energy consumption. Dries up quickly. According to reliable information, China's industrial energy consumption occupies the largest share of the overall cost, while the effective utilization rate of energy is only about 30%, and the cost is much higher than that of developed countries in Europe. Therefore, considering the economic benefits, the promotion of energy-saving equipment It's an imperative move. The shortage of energy is a serious test facing the whole world at present. To seek development under such a big background, the development of new and new energy is one aspect, and the more important thing is to make great efforts to save energy. At present, the design and development of domestic waste heat energy-saving boilers have gradually matured. With the development of society, people will increasingly find that energy-saving equipment is an inevitable trend. The signboard of the energy-saving boiler is not only a major weight for business promotion, but also a major contribution to society and the environment.
