Efficient power generation method for heat recovery coke oven adopting power coal

Abstract

The invention relates to an efficient power generation method for a heat recovery coke oven adopting power coal, which comprises the following steps: 1) taking the power coal as a coal charge, tamping and forming the coal charge into a coal cake, and forming grooves in the surface of the coal cake and / or forming holes in the coal cake; (2) increasing the air supply amount of the carbonization chamber, so that the coal gas generated after dry distillation is completely combusted, and meanwhile, the raw material coal and dry distillation coke in the carbonization chamber are combusted; finally, only residual ash and part of residual carbon in the coke oven are subjected to heat recovery; and 4) controlling the temperature of the discharged high-temperature flue gas to be between 1250 DEG C and 1350 DEG C, and introducing the high-temperature flue gas into the waste heat boiler to generate high-pressure steam for driving a steam turbine generator unit to generate electricity. According to the invention, sufficient combustion of the dry distillation product of the coal as fired and the fixed fuel is realized, and the purposes that the heat recovery coke oven adopts the power coal to generate electricity and the generating capacity is greatly increased are achieved.

Description

Technical Field

[0001] This invention relates to the field of heat recovery coke oven power generation technology, and in particular to a high-efficiency power generation method using thermal coal heat recovery coke oven. Background Technology

[0002] Heat recovery coke ovens (HRCOs) are core equipment in the coking industry for achieving cascaded energy utilization. Traditional processes primarily focus on coking, using high-quality coking coal with a volatile matter content of around 25%. Coke is produced through dry distillation and coking, while the high-temperature flue gas generated during coking is recovered as a byproduct to drive a waste heat boiler for power generation—a process known as "coke-electricity cogeneration." In this production model, the core function of the HRCO is focused on coke production. Flue gas generation is significantly affected by fluctuations in the coking cycle and coal loading. Furthermore, a large amount of coking coal energy is used to form fixed carbon in coke, resulting in low waste heat recovery efficiency, low power generation per ton of coke, and an overall energy utilization rate typically below 50%.

[0003] Thermal coal and coking coal are two distinctly different types of coal. Coking coal is primarily used in coke ovens for high-temperature dry distillation to produce metallurgical coke. Coking coal must possess good coking properties; that is, when heated to a certain temperature (approximately 950–1050°C) in the absence of air, it softens and melts, forming a gel-like substance, which then reforms and bonds together to form hard, porous, and high-strength coke. Thermal coal, on the other hand, is mainly used for direct combustion to generate power or heat, and typically lacks or has very weak coking properties. When heated, it does not soften and melt to form a gel-like substance; instead, it directly pulverizes or breaks apart, unable to bind into lumps.

[0004] Currently, some coking plants in China own coal mines, which produce not only coking coal but also thermal coal. Thermal coal is characterized by high volatile matter (28%–38%) and high calorific value (20–25 MJ / kg), and its market price is only 1 / 2 to 1 / 3 that of coking coal. Therefore, when building new heat recovery coke ovens, considering the use of thermal coal for power generation will help improve energy efficiency and reduce production costs.

[0005] On the other hand, with the increasing demand in the electricity market, coking enterprises urgently need to improve the power generation capacity of heat recovery coke ovens. However, the current heat recovery coke oven power generation technology has the following problems: 1. Low fuel utilization efficiency: The traditional production mode relies on coking coal, which has high fuel costs and energy distribution is centered on coke production. Waste heat from flue gas is only a by-product and cannot be maximized to be converted into electricity; 2. The power generation potential is not fully released: There is no combustion and waste heat recovery system for thermal coal, which means that thermal coal cannot be efficiently converted into electricity in traditional coke ovens, limiting the increase in power generation.

[0006] Therefore, the key to overcoming existing technological bottlenecks and significantly increasing the power generation of heat recovery coke ovens is to transform them from a "coke-electricity cogeneration" mode to a "power generation-oriented" high-efficiency power generation mode by switching fuel types and optimizing coal-fired and waste heat recovery systems. Summary of the Invention

[0007] This invention addresses the problems of traditional heat recovery coke ovens, such as reliance on coking coal, low power generation, and unstable flue gas parameters. It provides a method for high-efficiency power generation using thermal coal in a heat recovery coke oven. Thermal coal, processed with a special forming process, is used as the feed material for the heat recovery coke oven. By changing the thermal regime of the heat recovery coke oven, the dry distillation products of the feed material and the fixed fuel are fully combusted, thereby achieving the goal of using thermal coal to generate electricity in the heat recovery coke oven and significantly increasing power generation.

[0008] To achieve the above objectives, the present invention employs the following technical solution:

[0009] A method for high-efficiency power generation using a heat recovery coke oven equipped with a waste heat recovery system and a steam turbine generator set; the method includes the following processes:

[0010] 1) The heat recovery coke oven uses thermal coal as the feed material. The feed material is compacted into coal cakes. During the compaction process, grooves are formed on the surface of the coal cake and / or holes are formed in the coal cake to increase the contact area between the coal cake and air during combustion.

[0011] 2) The heat recovery coke oven is ignited and burned to heat and dry distill the coal fed into the oven; during this process, the air supply to the carbonization chamber is increased so that the coal gas produced after dry distillation is completely burned, and the raw coal and dry distilled coke in the carbonization chamber are burned at the same time; finally, only ash and some residual carbon remain in the heat recovery coke oven.

[0012] 4) The temperature of the high-temperature flue gas discharged from the heat recovery coke oven is kept stable between 1250 and 1350℃; the high-temperature flue gas is introduced into the waste heat boiler to generate high-pressure steam, which is used to drive the steam turbine generator set to generate electricity.

[0013] The volatile matter content of the thermal coal is 28% to 38%, and the calorific value is 20 to 25 MJ / kg. The thermal coal is pretreated by crushing and drying before being fed into the furnace.

[0014] The thermal coal undergoes crushing and drying pretreatment.

[0015] The holes formed in the coal cake are either through holes or closed holes.

[0016] The sealed cavity is filled with filler material, which is made of PVC or PE.

[0017] The increase in air supply to the carbonization chamber includes one or more of the following methods: increasing the diameter of the air distribution holes at the furnace top / flue, and increasing the number of air distribution holes at the furnace top / furnace door / fire passage.

[0018] A process hole is provided on the furnace door of the carbonization chamber. The operating rod is inserted into the furnace through the process hole to break the ash shell on top of the solid fuel and turn the solid fuel pile over so that the solid fuel can be fully burned.

[0019] The oxygen content in the air supplied to the carbonization chamber is 25% to 30% by volume.

[0020] The high-temperature flue gas discharged from the heat recovery coke oven enters the waste heat boiler through the flue gas equalization device.

[0021] The waste heat boiler is a high-efficiency waste heat boiler with membrane water-cooled walls and a superheater.

[0022] The system is equipped with a PLC+DCS-based control system to collect system process parameters in real time, including furnace temperature, flue gas flow rate, flue gas composition, steam pressure, steam temperature and power generation load. The system dynamically adjusts the air supply in the carbonization chamber and the opening of the turbine inlet valve through a PID algorithm to control the power generation fluctuation within ±5%.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] (1) Fuel substitution and process adaptation were achieved: The creative proposal to use thermal coal as the core fuel of heat recovery coke oven to replace traditional coking coal was put forward. Through fuel pretreatment and adaptable feeding method, the problem of incomplete combustion of large-volume tamped coal cake in coke oven was solved. All combustible volatiles and most fixed carbon of thermal coal were efficiently converted into high-temperature flue gas, and the fuel energy utilization rate was increased to more than 90%.

[0025] (2) Achieved oxygen-enriched combustion and temperature control: In response to the combustion requirements of power coal, an oxygen-enriched combustion system was set up. By increasing the oxygen concentration of the air entering the furnace (25%~30%) and optimizing the air intake structure, a stable oxidizing combustion atmosphere was constructed, and the temperature uniformity in the furnace was improved by more than 30%, effectively avoiding the problem of low combustion efficiency caused by the reducing atmosphere in traditional coking.

[0026] (3) The combustion process was optimized: In the high-temperature environment of the carbonization chamber, by optimizing the airflow direction in the furnace, the contact opportunities between the airflow and the coal cake surface were increased. While the oxygen and coal gas in the furnace reacted with the fixed carbon, the waste gas and excess heat after combustion were used to react with the fixed carbon, thereby strengthening the consumption of fixed carbon and increasing the total amount of heat energy converted by the coke oven.

[0027] (4) Achieved uniform flue gas flow and efficient heat exchange: A flue gas flow equalization device was added to eliminate the phenomenon of flue gas flow deviation. Combined with the enhanced heat exchange structure of the high-efficiency waste heat boiler, the high-temperature flue gas waste heat recovery efficiency was increased from the traditional 70% to more than 85%, and the power generation per unit of power coal reached 380-420 kWh / t, which is much higher than the power generation per ton of coke of traditional heat recovery coke oven (80-120 kWh / t).

[0028] (5) Achieved intelligent control of the whole process: Established a full-parameter intelligent control system covering combustion, heat exchange and power generation, dynamically adapted to the combustion characteristics of thermal coal and the power generation load demand, ensured stable operation of the system under different working conditions, and controlled the power generation fluctuation within ±5%. Attached Figure Description

[0029] Figure 1 This is a schematic diagram illustrating the principle of a high-efficiency coke oven power generation method using thermal coal heat recovery as described in this invention.

[0030] In the diagram: 1. Carbonization chamber; 2. Upper air inlet; 3. Lateral air inlet; 4. Lower air inlet; 5. Coal cake; 6. Groove; 7. Hole; 8. Packing material. Detailed Implementation

[0031] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings:

[0032] like Figure 1 As shown, the present invention discloses a method for high-efficiency power generation using a heat recovery coke oven equipped with a waste heat recovery system and a steam turbine generator set. The method for high-efficiency power generation using a heat recovery coke oven includes the following processes:

[0033] 1) The heat recovery coke oven uses thermal coal as the feed material. The feed material is compacted into coal cake 5. During the compaction process, grooves 6 are formed on the surface of the coal cake 5 and / or holes 7 are formed in the coal cake 5 to increase the contact area between the coal cake and air during combustion.

[0034] 2) The heat recovery coke oven is ignited and burned to heat and dry distill the coal fed into the oven; during this process, the air supply to the carbonization chamber 1 is increased so that the coal gas produced after dry distillation is completely burned, and the raw coal and dry distilled coke in the carbonization chamber 1 are burned at the same time; finally, only ash and some residual carbon remain in the heat recovery coke oven.

[0035] 4) The temperature of the high-temperature flue gas discharged from the heat recovery coke oven is kept stable between 1250 and 1350℃; the high-temperature flue gas is introduced into the waste heat boiler to generate high-pressure steam, which is used to drive the steam turbine generator set to generate electricity.

[0036] The volatile matter content of the thermal coal is 28% to 38%, and the calorific value is 20 to 25 MJ / kg. The thermal coal is pretreated by crushing and drying before being fed into the furnace.

[0037] The thermal coal undergoes crushing and drying pretreatment.

[0038] The holes 7 formed in the coal cake 5 are either through holes or closed holes.

[0039] The sealed cavity is provided with filler 8, which is made of PVC or PE material.

[0040] The increase in air supply to carbonization chamber 1 includes one or more of the following methods: increasing the diameter of the air distribution holes at the furnace top / flue, increasing the number of air distribution holes at the furnace top / furnace door / fire passage (e.g.) Figure 1 The upper air inlet 2, the side air inlet 3, and the lower air inlet 4 are located in the middle.

[0041] A process hole is provided on the furnace door of the carbonization chamber. The operating rod is inserted into the furnace through the process hole to break the top ash shell of the solid fuel (raw coal and dry distillation coke) and turn the solid fuel pile over so that the solid fuel can be fully burned.

[0042] The oxygen content in the air supplied to the carbonization chamber is 25% to 30% by volume.

[0043] The high-temperature flue gas discharged from the heat recovery coke oven enters the waste heat boiler through the flue gas equalization device.

[0044] The waste heat boiler is a high-efficiency waste heat boiler with membrane water-cooled walls and a superheater.

[0045] The system is equipped with a PLC+DCS-based control system to collect system process parameters in real time, including furnace temperature, flue gas flow rate, flue gas composition, steam pressure, steam temperature and power generation load. The system dynamically adjusts the air supply in the carbonization chamber and the opening of the turbine inlet valve through a PID algorithm to control the power generation fluctuation within ±5%.

[0046] The present invention describes a high-efficiency power generation method using a heat recovery coke oven with thermal coal. Unlike the traditional heat recovery coke oven process used for coke production, this method uses unconventional raw material—thermal coal—as the feed material. The coal is heated and dry-distilled to produce coal gas, which is then completely combusted to release heat. At the same time, the operation of the heat recovery coke oven is adjusted to enhance the combustion of solid fuels. Furthermore, a waste heat recovery system is used to recover the heat from the high-temperature flue gas, ultimately increasing the power generation of the steam turbine power generation system.

[0047] The core of the efficient power generation method for coke ovens using thermal recovery of power coal described in this invention is to increase the amount of air entering the carbonization chamber to fully combust the coal gas produced by the dry distillation of raw coal, while simultaneously combusting the raw coal and dry distilled coke in the carbonization chamber.

[0048] This invention improves upon the traditional heat recovery coke oven structure. Based on the air introduction scheme designed for coke production in the original heat recovery coke oven, it increases the amount of air introduced from the upper, side and lower parts of the carbonization chamber by increasing the diameter of the air distribution holes at the top of the furnace and the flue, and increasing the number of air distribution holes at the top of the furnace, the furnace door and the fire passage, thereby ultimately achieving the purpose of enhanced combustion of solid fuel.

[0049] In traditional heat recovery coke ovens, the coal feed is compacted into rectangular coal cakes. In this invention, during the compaction process, grooves are formed on the surface of the coal cake using an extrusion molding die or an extrusion molding operation, or through-holes are formed in the coal cake, or cavities are formed in the coal cake using fillers, or any combination of two or more of the above three methods are used. The purpose is to ensure that the coal cake or coke cake is in full contact with air, so as to enhance combustion and increase heat conversion, thereby creating conditions for ultimately increasing power generation.

[0050] The present invention discloses a high-efficiency power generation method using a thermal coal heat recovery coke oven, which is based on a modified heat recovery coke oven system. The specific process is as follows:

[0051] 1. Fuel selection and pretreatment: Select thermal coal with high volatile content, but not suitable for coke production. After crushing and drying pretreatment, store it in the raw coal bunker.

[0052] 2. Coal loading: In the process of making coal cakes using a tamping machine, fillers or tamping molds are used to increase the contact area between the coal cake and air during combustion by forming holes or cavities inside the coal cake or grooves on the surface of the coal cake.

[0053] 3. Excessive air combustion control: Unlike traditional heat recovery coke ovens that require controlling coke cake burn-off and only burning the raw coal gas discharged during coal cake distillation, this invention requires increasing the air supply to ensure complete combustion of the raw coal gas produced by the dry distillation of power coal, while simultaneously burning the raw coal and dry distilled coke in the carbonization chamber. By enhancing the combustion of fixed carbon, the heat energy conversion of the coke oven is increased, and ultimately only ash and some residual carbon remain in the heat recovery coke oven.

[0054] To ensure the safe operation of the heat recovery coke oven and increase its thermal energy conversion efficiency, an appropriate amount of air beyond the theoretical combustion calculation should be introduced to stabilize the temperature of the exhaust gas from the heat recovery coke oven at 1250–1350℃ (target value 1300℃).

[0055] 4. Flue gas waste heat recovery: The high-temperature flue gas generated by the heat recovery coke oven enters the high-efficiency waste heat boiler, and through the heat exchange structure of membrane water-cooled wall + superheater, high-pressure steam is generated to drive the steam turbine generator set to generate electricity.

[0056] 5. Intelligent control and stable operation: Equipped with a PLC+DCS-based control system, it collects parameters such as furnace temperature, flue gas flow rate, flue gas composition, steam pressure, steam temperature, and power generation load in real time. Through PID algorithm, it dynamically adjusts the air supply and turbine inlet valve opening to ensure stable system operation.

[0057] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for high-efficiency power generation using a heat recovery coke oven equipped with a waste heat recovery system and a steam turbine generator set; characterized in that, The high-efficiency power generation method using heat recovery coke ovens includes the following processes: 1) The heat recovery coke oven uses thermal coal as the feed material. The feed material is compacted into coal cakes. During the compaction process, grooves are formed on the surface of the coal cake and / or holes are formed in the coal cake to increase the contact area between the coal cake and air during combustion. 2) The heat recovery coke oven is ignited and burned to heat and dry distill the coal fed into the oven; during this process, the air supply to the carbonization chamber is increased so that the coal gas produced after dry distillation is completely burned, and the raw coal and dry distilled coke in the carbonization chamber are burned at the same time; finally, only ash and some residual carbon remain in the heat recovery coke oven. 4) The temperature of the high-temperature flue gas discharged from the heat recovery coke oven is kept stable between 1250 and 1350℃; the high-temperature flue gas is introduced into the waste heat boiler to generate high-pressure steam, which is used to drive the steam turbine generator set to generate electricity.

2. The method for high-efficiency power generation from a coke oven using thermal coal heat recovery as described in claim 1, characterized in that, The volatile matter content of the thermal coal is 28% to 38%, and the calorific value is 20 to 25 MJ / kg. The thermal coal is pretreated by crushing and drying before being fed into the furnace.

3. The method for high-efficiency power generation from a coke oven using thermal coal heat recovery as described in claim 1, characterized in that, The holes formed in the coal cake are either through holes or closed holes.

4. The method for high-efficiency power generation from a coke oven using thermal coal heat recovery according to claim 3, characterized in that, The sealed cavity is filled with filler material, which is made of PVC or PE.

5. A method for high-efficiency power generation from a coke oven using thermal coal heat recovery as described in claim 1, characterized in that, The increase in air supply to the carbonization chamber includes one or more of the following methods: increasing the diameter of the air distribution holes at the furnace top / flue, and increasing the number of air distribution holes at the furnace top / furnace door / fire passage.

6. A method for high-efficiency power generation from a coke oven using thermal coal heat recovery, as described in claim 1 or 2, characterized in that... A process hole is provided on the furnace door of the carbonization chamber. The operating rod is inserted into the furnace through the process hole to break the ash shell on top of the solid fuel and turn the solid fuel pile over so that the solid fuel can be fully burned.

7. A method for high-efficiency power generation from a coke oven using thermal coal heat recovery as described in claim 1, characterized in that, The oxygen content in the air supplied to the carbonization chamber is 25% to 30% by volume.

8. A method for high-efficiency power generation from a coke oven using thermal coal heat recovery as described in claim 1, characterized in that, The high-temperature flue gas discharged from the heat recovery coke oven enters the waste heat boiler through the flue gas equalization device.

9. A method for high-efficiency power generation from a coke oven using thermal coal heat recovery as described in claim 1, characterized in that, The waste heat boiler is a high-efficiency waste heat boiler with membrane water-cooled walls and a superheater.

10. A method for high-efficiency power generation from a coke oven using thermal coal heat recovery as described in claim 1, characterized in that, The system is equipped with a PLC+DCS-based control system to collect system process parameters in real time, including furnace temperature, flue gas flow rate, flue gas composition, steam pressure, steam temperature and power generation load. The system dynamically adjusts the air supply in the carbonization chamber and the opening of the turbine inlet valve through a PID algorithm to control the power generation fluctuation within ±5%.

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