A boiler auxiliary heating system for accommodating new energy electric energy

Abstract

The utility model discloses a kind of for the boiler auxiliary heating system of new energy power consumption, belong to electric heating equipment technical field, including coal-fired boiler system, the coal-fired boiler system includes economizer and steam drum communicated by feedwater pipe, economizer is equipped with parallel secondary water electric heating unit between steam drum, the secondary water electric heating unit includes heat conducting oil heat exchanger and heat conducting oil heater communicated by oil circuit, the heat conducting oil heater is used to heat and drive heat conducting oil and circulate flow between heat conducting oil heat exchanger and heat conducting oil heater, the water outlet of economizer is equipped with three-way switch valve, and the three-way switch valve is used to connect feedwater pipe or heat conducting oil heat exchanger. The utility model adds secondary water electric heating unit and secondary wind power heating unit in coal-fired boiler system, which helps to consume abandoned electricity and reduce coal combustion.

Description

Technical Field

[0001] This utility model belongs to the field of electric heating equipment technology, and specifically relates to a boiler auxiliary heating system for absorbing new energy power. Background Technology

[0002] In northern my country, wind and solar power resources are abundant, but the transmission capacity of load centers (eastern coastal areas) is limited. For example, in 2016, only 26% of wind and solar power was transmitted through ultra-high voltage lines. Although this figure rose to 36% in 2017, the total amount transmitted was still less than 8% of the wind and solar power generated in the "Three Norths" region.

[0003] The volatility and randomness of wind and solar power make it difficult to maintain a stable balance between power grid supply and demand, resulting in frequent instances of wind and solar power curtailment across the country. To facilitate the integration of renewable energy generation, the government is striving to build a new power system from multiple perspectives, including grid, power source, load, and energy storage. In general, the integration of new energy sources depends on the cooperation of other flexible power generation resources.

[0004] Among existing flexibility resources, upgrading coal-fired power units through equipment modifications is currently the most economical and reasonable approach. Looking at existing coal-fired power unit flexibility upgrade targets, the peak-shaving target for pure condensing units is generally 30% ECR, with a small number targeting 20% ​​ECR. Most regions across the country have already carried out flexibility upgrades for coal-fired power units. Further absorption of renewable energy generation depends on further lowering the peak-shaving target for pure condensing units, or the deployment of units with rapid start-up and shutdown capabilities.

[0005] Based on this, we propose a boiler auxiliary heating system for absorbing new energy power. Utility Model Content

[0006] The purpose of this utility model is to provide an auxiliary heating boiler system for absorbing electrical energy. By upgrading the original coal-fired boiler system, it enables it to absorb abandoned electricity and at the same time helps to reduce coal consumption.

[0007] An auxiliary heating boiler system for absorbing electrical energy includes a coal-fired boiler system. The coal-fired boiler system includes an economizer and a steam drum connected by a feedwater pipe. A secondary water-electric heating unit is provided between the economizer and the steam drum, connected in parallel with the feedwater pipe. The secondary water-electric heating unit includes a thermal oil heat exchanger and a thermal oil heater connected by an oil circuit. The thermal oil heater is used to heat and drive the thermal oil to circulate between the thermal oil heat exchanger and the thermal oil heater. The outlet of the economizer is provided with a three-way switching valve, which is used to connect the feedwater pipe or the thermal oil heat exchanger.

[0008] The thermal oil heater is powered on to heat the thermal oil and pumps the thermal oil into the thermal oil heat exchanger. The thermal oil heats the water supplied by the economizer in a secondary manner through the thermal oil heat exchanger. The thermal oil circulates between the thermal oil heat exchanger and the thermal oil heater.

[0009] Furthermore, the economizer is connected in sequence to the selective catalytic reduction reactor and the air preheater through the flue gas pipeline. The air preheater is connected to the secondary air box of the boiler burner through the air supply pipeline. A secondary air electric heating unit is set between the air preheater and the secondary air box of the burner. The secondary air electric heating unit includes a heating air box, and the heating air box is equipped with multiple rows of high-temperature electric heating tubes.

[0010] After the high-temperature electric heating tube is powered on, it reheats the air flowing out of the air preheater, thereby increasing the temperature of the air introduced into the secondary air box of the boiler burner.

[0011] Furthermore, it also includes a power control system, which is electrically connected to the secondary water-electric heating unit and the secondary air-electric heating unit respectively. The power control system is used to regulate the heating power of the secondary water-electric heating unit and the secondary air-electric heating unit respectively, so as to ensure the safe operation of the secondary water-electric heating unit and the secondary air-electric heating unit.

[0012] Furthermore, the air preheater is a rotary air preheater, which includes a primary air compartment, a secondary air compartment, and a flue gas passage. The secondary air compartment is connected to the heating air box, and the flue gas passage is connected to the economizer.

[0013] Furthermore, the high-temperature electric heating tube is a silicon carbide high-temperature electric heating tube.

[0014] Furthermore, the heat transfer oil heat exchanger is a tubular heat exchanger.

[0015] Furthermore, the heat-conducting oil heater has multiple sets of nickel-chromium alloy electric heating tubes built in.

[0016] The present invention has the following beneficial effects.

[0017] 1. This utility model adds a secondary water and electricity heating unit to the original coal-fired boiler system to reheat the water supplied from the economizer to the steam drum, thereby increasing the enthalpy of the water before it enters the steam drum and increasing the proportion of heat absorbed by the boiler feedwater through evaporation. This helps to prevent the boiler's high-temperature heating surface from overheating under low load and reduces the amount of desuperheating water used.

[0018] 2. Adding a secondary air-powered heating unit to a coal-fired boiler system can significantly improve the boiler's stable combustion capability and pulverized coal combustion rate by reheating the air supplied from the air preheater to the secondary air box of the boiler burner when the load is reduced during peak shaving. This is beneficial for improving the unit's economy and safety.

[0019] 3. The power control system separately regulates the heating power of the secondary water and electricity heating unit and the secondary wind power heating unit to ensure the safe operation of the equipment. It helps to reduce the amount of coal fed into the boiler while keeping the output of the coal-fired boiler unchanged, which can both absorb the abandoned electricity and benefit the environment. Attached Figure Description

[0020] Figure 1 This is a connection diagram of a boiler auxiliary heating system for absorbing new energy power, as described in this utility model.

[0021] Figure 2 This is a schematic diagram of the connection structure of the secondary water and electricity heating unit in this utility model.

[0022] Figure 3 This is a schematic diagram of the connection structure of the secondary wind power heating unit in this utility model.

[0023] In the diagram: 10. Steam drum; 20. Economizer; 21. Feedwater pipe; 30. Secondary water and electric heating unit; 31. Thermal oil heat exchanger; 32. Thermal oil heater; 33. Three-way switching valve; 40. Selective catalytic reduction reactor; 50. Air preheater; 51. Flue gas passage; 52. Primary air compartment; 53. Secondary air compartment; 60. Secondary air electric heating unit; 61. Heating air box; 62. High-temperature electric heating tube; 70. Power control system; 80. Boiler burner secondary air box. Detailed Implementation

[0024] Example 1

[0025] In a coal-fired boiler system, the inlet of the economizer 20 is connected to an external water supply pipeline, and its outlet is connected to the steam drum 10 via a feedwater pipe 21. The economizer 20 is a heat exchange device arranged in the flue gas duct at the tail end of the boiler, using the heat from the flue gas to heat the boiler feedwater. This embodiment provides a boiler auxiliary heating system for absorbing new energy electrical energy. A secondary water and electricity heating unit 30 is installed between the economizer 20 and the steam drum 10. The secondary water and electricity heating unit 30 is used to heat the water supply flowing from the economizer 20 to the steam drum 10. The secondary water and electricity heating unit 30 includes a thermal oil heat exchanger 31 and a thermal oil heater 32. The thermal oil heat exchanger 31 is a tubular heat exchanger connected in parallel with the water supply pipe 21. A three-way switching valve 33 is provided between the liquid inlet of the thermal oil heat exchanger 31 and the water outlet of the water supply pipe 21, used to switch the connection between the economizer 20 and the water supply pipe 21, or between the economizer 20 and the thermal oil heat exchanger 31. A valve body is provided at the liquid outlet of the water supply pipe 21 and the thermal oil heat exchanger 31 respectively. The thermal oil heater 32 is connected to the thermal oil heat exchanger 31 through an oil circuit. The thermal oil circulates between the thermal oil heater 32 and the thermal oil heat exchanger 31. The thermal oil heater 32 has multiple sets of nickel-chromium alloy electric heating tube arrays built in rows or staggered rows. After external power supply, the electric heating tubes heat the thermal oil, and the built-in circulation pump drives the thermal oil to circulate. The secondary water-electric heating unit 30 is electrically connected to the power control system 70. The power control system 70 is used to adjust the electric heating power of the thermal oil heater 32 to ensure that the water entering the boiler drum 10 retains sufficient sub-enthalpy according to safety requirements and saturation. The power control system 70 includes a power distribution module for distributing heating power according to the grid-connected electricity price signal (the electricity ancillary service market or electricity spot trading price indirectly reflects the consumption of new energy power generation); a temperature feedback module connected to temperature sensors installed at the inlet and outlet of the thermal oil heat exchanger 31 and the outlet temperature sensor of the economizer 20; and a safety protection module for setting over-temperature alarm thresholds.

[0026] This embodiment enables the following: when external factors cause the curtailment of renewable energy, the coal-fired power unit generates peak-shaving demand. The curtailed power will be indirectly introduced into the boiler auxiliary heating system by increasing the plant power consumption rate. After secondary heating by the economizer 20 and the thermal oil heat exchanger 31, the external water supply flows into the steam drum 10. The power control system 70 controls and adjusts the thermal oil heater 32. After being heated in the thermal oil heater 32, the thermal oil flows into the thermal oil heat exchanger 31 and exchanges heat with the water supply in the thermal oil heat exchanger 31. The curtailed power is used for the coal-fired boiler system, which increases the enthalpy of the water supply before entering the steam drum 10 and increases the proportion of heat absorbed by the boiler feedwater through evaporation. This helps prevent the boiler's high-temperature heating surface from overheating under low load, reduces the amount of desuperheating water used, and helps reduce the amount of coal consumed.

[0027] Example 2

[0028] Example 2 is a further improvement based on Example 1.

[0029] In a coal-fired boiler system, flue gas flows through economizer 20 into selective catalytic reduction (SCR) reactor 40 for denitrification. The denitrified flue gas then enters air preheater 50, where it exchanges heat with the cold air entering the boiler. Air preheater 50 is connected to boiler burner secondary air box 80, used to deliver preheated air to boiler burner secondary air box 80. This embodiment provides a boiler auxiliary heating system for absorbing new energy electricity, including a secondary air electric heating unit 60 disposed between boiler burner secondary air box 80 and air preheater 50. The secondary air electric heating unit 60 is used to secondary heat the air discharged from the preheater. The secondary air electric heating unit 60 includes a heating air box 61, one end of which is connected to air preheater 50, and the other end is connected to boiler burner secondary air box 80. Heating air box 61 is equipped with multiple rows of high-temperature electric heating tubes 62. The secondary air electric heating unit 60 is electrically connected to power control system 70, which controls and adjusts the heating power of the high-temperature electric heating tubes 62 to ensure safe system operation.

[0030] The high-temperature electric heating tube 62 is a silicon carbide high-temperature electric heating tube 62, which is arranged in a straight line or staggered line.

[0031] The air preheater 50 is a rotary air preheater 50, which includes a primary air compartment 52, a secondary air compartment 53, and a flue gas passage 51. The secondary air compartment 53 is connected to the secondary air electric heating unit 60, and the flue gas passage 51 is connected to the economizer 20. This embodiment enables the introduction of this auxiliary heating system to address the peak-shaving demand of coal-fired power units when external factors cause renewable energy curtailment. The curtailed power is introduced by increasing the plant's power consumption rate. External air flows sequentially through the air preheater 50, the secondary air electric heating unit 60, and the boiler burner secondary air box 80. The air preheater 50 provides primary heating to the external air, and the secondary air electric heating unit 60 provides secondary heating.

[0032] When the unit participates in peak shaving, the load decreases and the boiler's stable combustion capacity declines. However, after the secondary hot air is heated twice by electric heating, the boiler's stable combustion capacity and pulverized coal combustion rate will be significantly improved, which will help improve the unit's economy and safety.

[0033] Working principle:

[0034] When the power grid issues a deep adjustment order or the spot market electricity price falls below a certain economic threshold, resulting in power curtailment, the power will be indirectly introduced into the coal-fired boiler system by increasing the plant's power consumption rate. Water will be supplied to the steam drum 10 through the secondary hydroelectric heating unit 30 heating the economizer 20. At the same time, air will be supplied to the secondary air box 80 of the boiler burner through the secondary air electric heating unit 60 heating the air preheater 50. This allows electrical energy to enter the boiler thermal system in the form of heat, reducing the amount of coal fed into the boiler while maintaining the output of the coal-fired boiler. The consumed electricity is produced by new energy sources, thus being equivalent to consuming green electricity (through price mechanism transmission), achieving the goal of carbon reduction for the unit. Furthermore, the effective utilization of curtailed electricity contributes to a significant increase in the absorption of new energy sources on a macro level.

[0035] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A boiler auxiliary heating system for accommodating new energy electric energy, comprising a coal-fired boiler system, the coal-fired boiler system comprising an economizer and a steam drum communicated by a feedwater pipe, characterized in that, A secondary water and electric heating unit is provided between the economizer and the steam drum, connected in parallel with the feedwater pipe. The secondary water and electric heating unit includes a heat transfer oil heat exchanger and a heat transfer oil heater connected by an oil circuit. The heat transfer oil heater is used to heat and drive the heat transfer oil to circulate between the heat transfer oil heat exchanger and the heat transfer oil heater. A three-way switching valve is provided at the outlet of the economizer. The three-way switching valve is used to connect the feedwater pipe or the heat transfer oil heat exchanger.

2. The boiler auxiliary heating system as described in claim 1, characterized in that, The economizer is connected in sequence to the selective catalytic reduction reactor and the air preheater through the flue gas pipeline. The air preheater is connected to the secondary air box of the boiler burner through the air supply pipeline. A secondary air electric heating unit is set between the air preheater and the secondary air box of the burner. The secondary air electric heating unit includes a heating air box, and the heating air box is equipped with multiple rows of high-temperature electric heating tubes.

3. The boiler auxiliary heating system as described in claim 2, characterized in that, It also includes a power control system, which is electrically connected to the secondary water heating unit and the secondary air heating unit respectively. The power control system is used to adjust the heating power of the secondary water heating unit and the secondary air heating unit respectively.

4. The boiler auxiliary heating system as described in claim 2, characterized in that, The air preheater is a rotary air preheater, which includes a primary air compartment, a secondary air compartment, and a flue gas passage. The secondary air compartment is connected to the heating air box, and the flue gas passage is connected to the economizer.

5. The boiler auxiliary heating system as described in claim 2, characterized in that, The high-temperature electric heating tube is a silicon carbide high-temperature electric heating tube.

6. The boiler auxiliary heating system as described in claim 1, characterized in that, The heat exchanger is a tubular heat exchanger.

7. The boiler auxiliary heating system as described in claim 1, characterized in that, The heat-conducting oil heater has multiple sets of nickel-chromium alloy electric heating tubes built in.

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