CN103195528A - Method and device for generating power through low-temperature waste gas waste in industrial furnace production technology - Google Patents

Abstract

The invention discloses a method and device for power generation of low-temperature waste gas waste heat in the production process of an industrial kiln. The cooling device in the existing process is replaced by the heat extraction equipment of the generator set, or the heat extraction equipment is directly placed at the exhaust gas outlet of the industrial kiln. The expansion machine is driven by the circulation loop formed by the expander, heat release equipment, high-pressure working fluid pump and heat extraction equipment to drive the low-temperature thermal double-cycle generator to generate power and extract the low-grade waste heat from the exhaust gas of industrial kilns, which is beneficial to the exhaust gas. While cooling down, the absorbed heat is sent to the generator set to be converted into electrical energy, and the waste gas after power generation is returned to the original process system or discharged into the atmosphere. In order to effectively improve the utilization rate of low-grade industrial kiln exhaust waste heat, reduce enterprise operating costs, and reduce thermal pollution to the environment.

Description

Method and device for power generation with low-temperature waste gas waste heat in industrial kiln production process

technical field

The present invention relates to a waste gas waste heat recovery power generation method and its device, in particular to a method for cooling the waste heat gas discharged in the production process of an industrial kiln, and using the waste heat discharged in the cooling process to generate electricity to achieve waste heat recovery and utilization Methods and Apparatus.

Background technique

Energy is the material basis of the national economy and the driving force behind economic development, and the efficient use of energy is an important guarantee for sustainable economic development. The recovery and utilization of industrial waste heat has become an increasingly important role in energy conservation and emission reduction. At present, high-temperature and medium-temperature exhaust gas waste heat recovery and power generation technologies have been widely promoted, but for low-temperature waste heat, heat exchange is currently the main method, and a large number of Low-grade waste heat is directly discharged in the form of waste heat.

Industrial kiln is a vital thermal equipment for smelting, roasting, sintering, melting, heating, etc. of materials or workpieces in ceramics, metallurgy, building materials, petrochemical and other industries, and it is also an important source of energy consumption and environmental thermal pollution. The calorific value of the waste gas exhausted by industrial kilns accounts for more than 20% of the total energy consumption of the kiln, but the waste heat utilization rate of the waste gas is only 4-5%, and the energy saving potential is huge. Solving the energy saving problem of industrial kiln equipment is very important for the above industries and The sustainable development of our country's national economy has a significant role in promoting.

Usually, the ways to utilize flue gas waste heat mainly include: 1. Install a preheater to preheat combustion-supporting air and fuel with flue gas; 2. Install a waste heat boiler to generate hot water or steam for production or domestic use; 3. Use the flue gas as a heat source for a low temperature furnace or to preheat a cold workpiece or charge. The most effective and widely used method for recovering flue gas waste heat is the heat exchanger, and the exhaust gas discharge temperature after the initial utilization of the waste heat is below 200°C.

With the rapid development of my country's economy, my country's industrial demand for power resources is increasing. If the waste heat in the exhaust gas of the kiln is converted into electric energy for the enterprise's own use, it will achieve a win-win situation for the economic and environmental benefits of the enterprise.

Contents of the invention

The purpose of the present invention is to provide a method and device for power generation with low-temperature waste gas waste heat in the production process of industrial kilns. The low-temperature thermal double-cycle power generation technology is applied to the waste heat of exhausted waste gas after the initial utilization of industrial kilns, so as to reduce waste heat discharge and improve energy efficiency.

In the existing industrial kiln production process, the exhaust gas after preliminary utilization is either directly emptied, or emptied after material recovery and exhaust gas purification, so that the heat is finally discharged into the atmosphere, resulting in waste and heat pollution.

The low-temperature waste gas waste heat power generation method of the industrial kiln production process of the present invention is to replace the cooling device in the existing process with the heat extraction equipment of the low-temperature thermal double-cycle generator set, or directly place the heat extraction equipment at the exhaust gas outlet of the industrial kiln to extract industrial The kiln evacuates the low-grade waste heat in the waste gas. While cooling the waste gas, it sends the absorbed heat to the generator set to convert it into electrical energy. After power generation, the waste gas is returned to the original process system or discharged into the atmosphere. In this way, the utilization rate of low-grade industrial kiln exhaust waste heat is effectively improved, the operating cost of the enterprise is reduced, and the heat pollution to the environment is reduced.

The low-temperature waste gas and waste heat power generation device of the industrial kiln production process of the present invention includes a preliminary utilization device for industrial kiln waste gas, a heat extraction device, and a material recovery or flue gas purification device connected in sequence through an exhaust gas pipeline, and a power generation device is connected to the heat extraction device. unit. Wherein, the generator set is composed of a low-temperature thermal double-cycle generator, an expander, heat release equipment and a high-pressure working medium pump, and a circulation loop for the flow of power generation medium is formed between the expander, heat release equipment and heat extraction equipment, and A high-pressure working medium pump that drives the flow of the power generation medium is arranged on the circulation loop, and a low-temperature thermal double-cycle generator is connected to the expander, which is driven by the expander to generate power. A cooling water circuit is also provided on the exothermic equipment.

The working process of the low-temperature waste gas waste heat power generation device of the industrial kiln production process of the present invention is: the waste gas produced by the industrial kiln passes through the waste gas preliminary utilization device, enters the heat extraction equipment, and exchanges heat with the power generation medium in it, and the power generation medium becomes a high-pressure gaseous state Entering the expander, the expander expands and does work to drive the generator to run to generate electricity. After power generation, the low-pressure gas-liquid two-phase power generation medium enters the heat release equipment, exchanges heat with cooling water, and becomes liquid, and then pumps it into the heat extraction equipment through high-pressure working fluid to continue to absorb the heat of the exhaust gas, and at the same time the cooling water will take it away After the heat is released, it can be recycled. After heat exchange with the power generation medium, the exhaust gas enters the material recovery or flue gas purification device, and is emptied after treatment.

The invention combines the low-temperature thermal double-cycle generator set with the waste heat system of industrial kiln waste gas, and recovers the waste heat in the waste gas after preliminary utilization to generate electricity. The lowest temperature after power generation can reach 50°C, and the energy saving effect is remarkable. At the same time, the waste heat power generation process of the present invention does not affect the normal operation of the original process, has dual functions, and achieves the purpose of energy saving and emission reduction.

Description of drawings

Fig. 1 is a schematic structural diagram of a low-temperature waste gas waste heat power generation device for an industrial kiln production process of the present invention.

In the figure: 1-exhaust gas, 2-industrial kiln exhaust gas preliminary utilization device, 4-cooling water inlet, 5-cooling water outlet, 6-material recovery or flue gas purification device, 7-exhaust gas evacuation channel, 8-heat extraction Equipment, 9-generator set, 10-low temperature thermal double cycle generator, 11-expander, 12-high pressure working medium pump, 13-exothermic equipment.

Detailed ways

The device and method of the present invention will be further described below in conjunction with the accompanying drawings.

As shown in Figure 1, the low-temperature waste gas waste heat power generation device for industrial kiln production process includes a preliminary utilization device 2 for industrial kiln waste gas, heat extraction equipment, and a material recovery or flue gas purification device 6 connected sequentially through waste gas pipelines. The thermal equipment 8 is connected with a generator set 9 . The generator set 8 is composed of a low-temperature thermal double-cycle generator 10, an expander 11, a heat release device 13 and a high-pressure working medium pump 12, wherein the expander 11, the heat release device 13, the high-pressure working medium pump 12 and the heat extraction device 8 are jointly formed The circulation circuit for the flow of power generation medium, the output end of the heat extraction device 8 is connected to the input end of the expander 11, the output end of the expander 11 is connected to the input end of the heat release device 13, and the output end of the heat release device 13 is connected to the high pressure working medium pump After 12, connect to the input end of the heating device 8. The low-temperature thermal double-cycle generator 10 is connected to the expander 11, driven by the expander 11 to generate power. A cooling water inlet 4 and a cooling water outlet 5 are connected to the heat releasing device 13 to form a cooling water circuit for cooling the power generation medium.

The waste gas 1 produced by the industrial kiln passes through the initial utilization device 2 of the waste gas of the industrial kiln, and then enters the heat extraction device 8, where it exchanges heat with the power generation medium, and the power generation medium becomes a high-pressure gaseous state and enters the expander 11, so that the expander 11 expands and performs work Drive the low-temperature thermal double-cycle generator 10 to run to generate electric energy. After power generation, the low-pressure gas-liquid two-phase power generation medium enters the heat release equipment 13, exchanges heat with the cooling water, and becomes liquid, and then sends the liquid power generation medium into the heat extraction equipment 8 through the high-pressure working medium pump 12, and continues to absorb waste gas At the same time, the cooling water releases the heat taken away and then recycles it. The waste gas 1 after heat exchange and cooling with the power generation medium enters the material recovery or flue gas purification device 6 , and is emptied through the waste gas discharge channel 7 after being treated.

Taking a building material factory as an example, in its production process, the temperature inside the kiln is 1300°C, the exhaust gas from the kiln is cooled to 180°C after passing through the waste heat boiler, and the emission volume is 90,000 m3/h. The original process uses cooling and cooling, and after cooling and flue gas purification, it is discharged into the air, and the waste heat resources are not used.

After adopting the technological method of the present invention, the heat extraction equipment is used to replace the original cooling device, and waste heat power generation is carried out on the premise of ensuring the purification of the flue gas, and the temperature of the flue gas drops to 50° C. after power generation.

The enthalpy values of air at 180°C and 50°C are 455.39kJ/kg and 323.63kJ/kg respectively, the heat Q absorbed by the heat extraction equipment is 2531kW, and its power generation P is 127kW.

If the daily operation time is 24 hours and the annual operation time is 330 days, the annual power generation can reach 1002280kWh, saving 350 tons of standard coal per year and reducing carbon dioxide emissions by 764 tons per year. If the electricity price is calculated according to 0.8 yuan/kWh, it can save electricity costs of 800,000 yuan/year for enterprises, which has obvious environmental and economic benefits.

Claims (3)

1. The low-temperature waste gas waste heat power generation method of the industrial kiln production process is to replace the cooling device in the existing process with the heat extraction equipment of the low-temperature thermal double-cycle generator set, or directly place the heat extraction equipment at the exhaust gas outlet of the industrial kiln to extract industrial The kiln evacuates the low-grade waste heat in the waste gas. While cooling the waste gas, it sends the absorbed heat to the generator set to convert it into electrical energy. After power generation, the waste gas is returned to the original process system or discharged into the atmosphere. 2. Low-temperature exhaust gas waste heat power generation device for industrial kiln production process, including the initial utilization device for industrial kiln exhaust gas, heat extraction equipment, and material recovery or flue gas purification device connected in sequence through the exhaust gas pipeline, and the heat extraction equipment is connected with power generation A unit, wherein the generator set is composed of a low-temperature thermal double-cycle generator, an expander, heat release equipment and a high-pressure working medium pump, and a circulation loop for the flow of power generation medium is formed between the expander, heat release equipment and heat extraction equipment , and a high-pressure working medium pump driving the flow of the power generation medium is set on the circulation loop, and the low-temperature thermal double-cycle generator is connected to the expander, which is driven by the expander to generate power. 3. The power generating device according to claim 2, characterized in that a cooling water circuit is provided on the heat releasing equipment.

Images