WO2019237869A1

WO2019237869A1 - Multi-process coupled power generation system combusting fossil fuel and oxygen-rich combustion waste

Info

Publication number: WO2019237869A1
Application number: PCT/CN2019/086649
Authority: WO
Inventors: 闫凯; 韩彩凤
Original assignee: 上海锅炉厂有限公司
Priority date: 2018-06-15
Filing date: 2019-05-13
Publication date: 2019-12-19
Also published as: CN109028093A

Abstract

A multi-process coupled power generation system combusting fossil fuel and oxygen-rich combustion waste, comprising a fire coal boiler (B1), and further comprising an oxygen-rich combustion waste incinerator (A1); waste to be treated (AF1) and filtrate (AF2) are conveyed to the oxygen-rich combustion waste incinerator (A1), the temperature of high-temperature flue gas generated by the oxygen-rich combustion waste incinerator (A1) is lowered to T1 after passing through a bypass economizer (S11), the flue gas having a temperature of T1 is conveyed to a dioxin suppression device after sequentially passing through an evaporator (S23) and a superheater (S24), the temperature of the flue gas out of the dioxin suppression device is lowered to T2 after passing through a secondary economizer (S22), and the flue gas having a temperature of T2 is divided into two paths of flue gas, one path of the flue gas being conveyed, by means of a high-temperature fan (A3), to the hearth of the fire coal boiler (B1), and the other path of the flue gas entering, after being boosted by a recirculation fan (A4), the hearth of the oxygen-rich combustion waste incinerator (A1) through a primary air passage (A6) and a secondary air passage (A7) respectively. Said system has little influence on the combustion process of the fire coal boiler (B1), both greatly reducing the requirement for a method of introducing into the hearth of the fire coal boiler (B1), and reducing the degree of damage to a water cooling wall.

Description

Multi-process coupled power generation system using fossil fuel and oxygen-enriched garbage

Technical field

The invention relates to a boiler system, in particular to a multi-process coupled power generation system for burning fossil fuel and oxygen-enriched waste.

Background technique

With the development of the economy, the people's material living standards have been greatly improved. With the generation of a large amount of garbage, the garbage has caused serious pollution to the atmosphere, soil, and water sources, which has caused great harm to our living environment. It is urgent to solve the problem of garbage. . Statistics show that China's municipal solid waste removal volume has exceeded 215 million tons in 2016.

In accordance with the principles of "recycling, reducing and harmlessness" put forward by China for waste treatment and the characteristics of China's waste, in recent years, waste incineration technology has gradually become a new trend in China's waste treatment. However, the dioxins, chlorides, sulfur dioxide, nitrogen oxides and other pollutants produced by waste incineration need to be separately equipped with a complex flue gas purification system in the waste incineration power plant for processing, with large investment, high energy consumption, low purification efficiency, and traditional The efficiency of waste incineration generating units is only 18-25%.

For this reason, in recent years, some scholars have proposed to couple large coal-fired boilers with waste incinerators to solve the disadvantages of high waste incinerator pollutant treatment costs and low power generation efficiency. Among them, the flue gas side coupling introduces the tail gas generated by the waste incinerator into the coal-fired boiler, which saves the investment of the waste incinerator flue gas purification system equipment; the steam side coupling introduces the main steam generated by the waste incinerator into the thermal system of the coal-fired unit , The low-level garbage incinerator heat transfer part to high-energy coal-fired boilers to generate electricity, to achieve efficient use of waste heat.

However, in practical engineering design, there are two problems with this coupling idea: first, on the flue gas side, due to the characteristics of waste incineration, the flue gas generated by the waste incinerator is usually larger in volume and is also subject to a booster fan. Due to the limitation of working temperature, the temperature for introducing large-scale power generation boilers is also low, usually not higher than 450 ° C. These large amounts of low-temperature flue gas will have a serious impact on the hearth combustion boilers of large-scale power generation boilers, especially at low and medium loads. It is very likely that the fire extinguishing phenomenon of the furnace of large power generation boilers will endanger the safe operation of the boiler, which will greatly limit the capacity of the coupled waste incinerator. Second, on the steam side, how to properly and safely couple the heating surfaces of the two boilers still lacks effective ideas and methods.

Summary of the Invention

The purpose of the present invention is to greatly increase the capacity of the coupled waste incinerator while greatly reducing the investment in the flue gas purification system of the waste incineration boiler.

In order to achieve the above object, the technical solution of the present invention is to provide a multi-process coupled power generation system for burning fossil fuel and oxygen-enriched waste, including a coal-fired boiler, which is characterized in that it also includes an oxygen-enriched waste incinerator. The treated waste and filtrate are sent to an oxygen-enriched waste incinerator. The high-temperature flue gas generated by the oxygen-enriched waste incinerator is cooled to T1 after passing through the economizer. The T1 flue gas then passes through the evaporator and superheated in order. After being sent to the dioxin suppression device, the flue gas exiting the dioxin suppression device is cooled to T2 after passing through the secondary economizer. The flue gas with temperature T2 is divided into two paths, one is sent to the combustion engine through a high-temperature fan. In the hearth of the coal boiler, the other way is increased by the recirculation fan to enter the hearth of the oxygen-enriched waste incinerator through the primary air channel and the secondary air channel, respectively.

Preferably, the dioxin suppression device includes a CaO device and a cyclone separator.

Preferably, a primary economizer is provided on the primary air passage, and the primary economizer cools the flue gas having a temperature of T2 to T3.

Preferably, the working fluid is introduced from the economizer outlet of the coal-fired boiler and divided into two paths, one of which passes through the first economizer, the second economizer, the evaporator, and the superheater in order. The large-screen superheater of the coal-fired boiler is introduced later; the other way still maintains the state of liquid water after being heat-exchanged by the bypass economizer, and is introduced to the heating surface entrance of the hearth of the coal-fired boiler.

Preferably, the temperature of the high-temperature flue gas is not lower than 850 ° C, the T2 is not higher than 450 ° C, and the T3 is not lower than 200 ° C.

Preferably, it further comprises an air separation device, and high-purity oxygen separated after air is input into the air separation device passes into the primary air channel and the secondary air channel, respectively.

Preferably, the high-purity oxygen concentration entering the primary air passage and the secondary air passage is controlled between 25-30%.

Preferably, the flue gas having a temperature of T2 is introduced into the hearth of the coal-fired boiler from the cold ash hopper area of the coal-fired boiler through a coupled flue gas connection pipe.

Because the boiler coupling system provided by the present invention adopts an oxygen-enriched combustion method for treating garbage, the volume of coupled flue gas after the pressure of the high-temperature fan is increased is only the volume of flue gas generated by air combustion under the condition of burning the same amount of garbage and the same flue gas temperature About 20%. Such a small amount of flue gas not only has a small impact on the combustion process of the fossil fuel boiler, but also greatly reduces the requirements for the introduction of the furnace mode (the number of openings and the size of the openings on the water-cooled wall) of the fossil fuel boiler. At the same time, the damage to the water-cooled wall is reduced.

Due to the use of oxygen-enriched combustion to treat garbage, the following two aspects are conducive to the suppression of dioxins in the oxygen-enriched garbage incinerator:

(1) The total oxygen concentration in the primary and secondary air entering the furnace of the oxygen-enriched waste incinerator is between 25 and 30%, and the temperature of the flue gas at the outlet of the furnace of the oxygen-enriched waste incinerator can be easily obtained ( Usually this temperature can be controlled above 1000 ℃);

(2) The amount of flue gas at the outlet of the oxygen-enriched waste incinerator is about 60% to 70% of that during air combustion. Under the current cross-section size of the flue of the air-burned waste incinerator, the residence time of high-temperature flue gas can be increased by 50 At the same time, the dioxin concentration in the smoke can be reduced by more than 50%.

In order to suppress the generation of dioxins in the hearth of the oxygen-enriched waste incinerator, increasing the oxygen concentration in the flue gas is achieved by increasing pure oxygen instead of air, which will greatly reduce the coupled flue gas introduced into the fossil fuel-fired boiler. Volume.

In an oxygen-enriched waste incinerator system, both the primary air and secondary air have higher temperatures and oxygen concentrations than when the air is burned, which is very beneficial to the ignition of the garbage, the preliminary combustion process and even the entire combustion process.

In the coupling system, feed water is introduced from a certain stage outlet upstream of the heating surface of the fossil fuel-fired boiler furnace, and only a part of the feed water becomes steam that is introduced into the superheater heating surface of the fossil fuel-fired boiler, and most of the feed water is still liquid water. After the form is heated, it is introduced into the heating surface inlet of the furnace of the fossil fuel-fired boiler. Such a heating surface setting can ensure the heat transfer of the tail heating surface as much as possible under the condition of coupling the oxygen-enriched waste refuse incinerator under the conditions of ensuring the hydrodynamic safety of the fossil fuel boiler. Whether the incinerator works and the fossil fuel-fired boiler can operate normally, which greatly increases the flexibility of the coupling system operation.

From the perspective of energy consumption, although the air separation device is added, the final temperature of the working fluid has been significantly improved due to the coupling of the steam side, and the improvement of the cycle efficiency is significantly greater than the energy consumption reduction caused by the addition of the air separation device. Overall, the system Thermal efficiency has also increased significantly.

From the perspective of investment, due to the coupling of the fossil fuel boiler and the oxygen-enriched waste incinerator on the flue gas side and the steam side, the existing flue gas purification system for the use of fossil fuel boilers was rationally used, which greatly saved The flue gas purification system required for air-burning waste incinerators, thereby greatly reducing investment costs.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a multi-process coupled power generation system using fossil fuels and oxygen-enriched wastes according to the present invention.

detailed description

To make the present invention more comprehensible, preferred embodiments are described in detail below with reference to the accompanying drawings.

As shown in FIG. 1, a series-coupled power generation system of coal-fired and oxygen-enriched waste disclosed in this embodiment includes an oxygen-enriched waste incinerator A1 and a coal-fired boiler B1.

The waste to be processed AF1 and its filtrate AF2 enter the grate of the oxygen-enriched waste incinerator A1 to participate in the combustion. The temperature of the high-temperature flue gas at the outlet of the A1 furnace of the oxygen-enriched waste incinerator A1 is 1050 ° C, and the temperature is reduced to 650 ° C after passing the bypass economizer S11. The 650 ° C flue gas passes through the evaporator S23 and the superheater S24 in sequence, and then passes through the CaO spraying device and the cyclone separator A2. The dioxin is removed from the flue gas by adding CaO to the CaO adding and spraying device and removing the ash by the cyclone A2. After the flue gas exits the cyclone separator A2, it passes the secondary economizer S22 and is cooled to 450 ° C. The 450 ° C flue gas is divided into two paths: one is introduced into the furnace of coal-fired boiler B1 from the cold ash area of coal-fired boiler B1 via the coupled flue gas connection pipe after the pressure is increased by high-temperature fan A3; the other is recirculated fan A4 After the pressure is increased, it is passed into the primary air channel A6 and the secondary air channel A7, respectively, and enters the oxygen-enriched waste incinerator A1 as the primary air and secondary air to participate in the combustion of the waste to be processed AF1 and its filtrate AF2. One of the primary air is introduced from the lower part of the grate of the oxygen-enriched waste incinerator A1, and the secondary air is introduced from a certain height of the upper part of the grate of the oxygen-enriched waste incinerator A1.

At the same time, the high-purity oxygen separated after the air enters the air separation device A5 also passes into the primary air passage A6 and the secondary air passage A7. High-purity oxygen is separately mixed as part of the primary air and secondary air before the primary air and secondary air enter the furnace of the oxygen-enriched waste incinerator A1. The total oxygen concentration in the primary and secondary air entering the furnace of the oxygen-enriched waste incinerator A1 was 27%.

The primary air passage A6 is provided with a primary economizer S21, and the primary economizer S21 controls the temperature of the primary air entering the oxygen-enriched waste incinerator A1 furnace at 200 ° C.

The working fluid is introduced from the economizer outlet of the coal-fired boiler B1 and divided into two paths, one of which passes through the first economizer S21, the second economizer S22, the evaporator S23, and the superheater S24. The superheater, the superheater S24 and the big screen superheater exit the steam temperature difference to control around 10 ℃; the other way after the bypass economizer S11 heat exchange still maintains the state of liquid water, and lead to the furnace of the coal-fired boiler B1 At the inlet of the heating surface, a part of the heating surface in the oxygen-enriched waste incinerator A1 can be used to heat the reheated steam of a fossil fuel-fired boiler.

An activated carbon adsorption device is installed between the desulfurization device and the dust removal device connected to the coal-fired boiler B1.

Claims

A multi-process coupled power generation system using fossil fuels and oxygen-enriched waste, including a coal-fired boiler (B1), which is also characterized by an oxygen-enriched waste incinerator (A1), waste to be processed (AF1), and filtrate. (AF2) is sent to the oxygen-enriched waste incinerator (A1), and the high-temperature flue gas produced by the oxygen-enriched waste incinerator (A1) is cooled to T1 after passing the bypass economizer (S11), and the smoke at temperature T1 After passing through the evaporator (S23) and the superheater (S24), the gas is sent to the dioxin suppression device. The flue gas from the dioxin suppression device is cooled to T2 after passing through the secondary economizer (S22). The flue gas for T2 is divided into two channels, one is sent to the hearth of the coal-fired boiler (B1) by the high-temperature fan (A3), and the other is passed through the primary air passage (A6) and the second after the pressure is increased by the recirculation fan (A4). The secondary air channel (A7) enters the hearth of the oxygen-enriched waste incinerator (A1).
The multi-process coupled power generation system for burning fossil fuel and oxygen-enriched waste according to claim 1, wherein the dioxin suppression device comprises a CaO device and a cyclone (A2).
The multi-process coupled power generation system for burning fossil fuel and oxygen-enriched waste according to claim 1, characterized in that a primary economizer (S21) is provided on the primary air passage (A6). The first-level economizer (S21) cools the flue gas with temperature T2 to T3.
The multi-process coupled power generation system for burning fossil fuel and oxygen-enriched waste according to claim 3, characterized in that the working medium is introduced from the economizer outlet of the coal-fired boiler (B1) and divided into two paths , All the way through the first-level economizer (S21), the second-level economizer (S22), the evaporator (S23) and the superheater (S24) in order to be introduced into the coal-fired boiler (B1) ) Large screen superheater; the other way still maintains the state of liquid water after heat exchange by the bypass economizer (S11), and leads to the entrance of the heating surface of the hearth of the coal-fired boiler (B1).
The multi-process coupled power generation system for burning fossil fuel and oxygen-enriched waste according to claim 3, wherein the temperature of the high-temperature flue gas is not lower than 850 ° C, and the T2 is not higher than 450 ° C. The T3 is not lower than 200 ° C.
The multi-process coupled power generation system for burning fossil fuel and oxygen-enriched garbage according to claim 1, further comprising an air separation device (A5), and the air separated after the air is input into the air separation device (A5). High-purity oxygen flows into the primary air passage (A6) and the secondary air passage (A7), respectively.
The multi-process coupled power generation system for burning fossil fuel and oxygen-enriched waste according to claim 6, characterized in that the height of the primary air passage (A6) and the secondary air passage (A7) is high. The purity oxygen concentration is controlled between 25-30%.
The multi-process coupled power generation system for burning fossil fuel and oxygen-enriched waste according to claim 1, characterized in that the flue gas at a temperature of T2 is obtained from the coal-fired boiler (B1) through a coupled flue gas connection pipe. The cold ash hopper area is introduced into the hearth of the coal-fired boiler (B1).