WO2015127836A1

WO2015127836A1 - Superheated steam boiler of horizontal circulating fluidized bed

Info

Publication number: WO2015127836A1
Application number: PCT/CN2015/070971
Authority: WO
Inventors: 康建斌; 胡峰; 李俊臣; 王谦; 胡彦霞; 徐进廷; 张哲�
Original assignee: 北京热华能源科技有限公司
Priority date: 2014-02-28
Filing date: 2015-01-19
Publication date: 2015-09-03
Also published as: CN103836612B; CN103836612A; TWI617773B; TW201533392A

Abstract

A superheated steam boiler of a horizontal circulating fluidized bed, comprising a primary combustion chamber, a secondary combustion chamber (14), a burnout chamber (15), a separator (17) and a tail flue (19), the primary combustion chamber and the secondary combustion chamber (14) are respectively provided with a high temperature radiation superheater (6) and a low temperature convection superheater (30) therein; a spray type desuperheater (4) is arranged between the two-stage superheaters; a bundle of tubes of the low temperature convection superheater (30) is obliquely arranged stepped towards the gas flow direction, thus facilitating material circulation and reducing ash accumulation. The steam boiler is an efficient superheated steam production device with clean combustion, a compact structure and a long service life.

Description

Horizontal circulating fluidized bed superheated steam boiler

Technical field

The invention relates to a circulating fluidized bed combustion device, in particular to a horizontal circulating fluidized bed steam boiler for producing superheated steam, which belongs to the combustion of inferior coal, solid waste, urban and industrial sludge, biomass and other inferior fuels. And steam generating equipment, especially suitable for steam utilization systems such as industrial heating and small power generation for burning inferior fuels.

Background technique

At present, boilers that use low-grade fuels such as inferior coal, solid waste, sludge, biomass, etc. to produce hot water and steam mainly include chain furnaces, water-cooled vibrating grate boilers, and circulating fluidized bed boilers, depending on the fuel. Different furnace types are selected for different characteristics, and different furnace types have their own characteristics. Hot water boilers are mainly used for urban heating, and steam boilers are mainly used for industrial heating and steam power generation.

Circulating fluidized bed boiler is a highly efficient and clean boiler technology developed in recent years. It has wide fuel adaptability and can be burned with high quality coal, inferior coal, solid waste, biomass and other fuels. Because of its high combustion efficiency, it can simultaneously carry out pollution control operations such as desulfurization and denitrification in the furnace, and has the advantages of low NOx and SOx emissions. Therefore, it has been rapidly developed in the power market and is developing in the direction of large-scale, 600MWe circulating flow. The chemical bed boiler has been put into commercial operation. In the power industry, the use of fuels such as inferior coal, solid waste, and biomass is likely to cause power generation downtime accidents. Therefore, the direct combustion applications of these fuels are limited, and they are actually adapted to higher quality fuels. On the contrary, in the fields of industrial boilers and self-contained small power plants, fuels such as inferior coal, solid waste, biomass, etc. are low due to the small amount of evaporation of the boiler, flexible operation, convenient maintenance, and the use of the parent system for the steam system. It is increasingly favored. Traditional vertical and single-stage circulating fluidized bed boilers have the disadvantages of high furnace height and large boiler island volume, which require high requirements for plant construction. At the same time, the supporting steel frame of the boiler island and the steel consumption of the boiler island body are relatively large, which makes the project cost and initial investment higher. In view of the defects of the vertical circulating fluidized bed boiler in the field of industrial boilers, the Chinese patent document CN200510126362.6 discloses a horizontal circulating fluidized bed combustion apparatus and a cyclic combustion method thereof, which adopts an external vertical cyclone separator and adopts a conventional The furnace of the vertical boiler is divided into three parts: the main combustion chamber, the auxiliary combustion chamber and the burnout chamber, thereby effectively reducing the height of the furnace. Chinese patent document CN201010110352.4 discloses a multi-process circulating fluidized bed boiler comprising a main combustion chamber, a secondary combustion chamber and a burnout chamber, and a blanking passage is left between the bottom surface of the burnout chamber and the bottom surface of the secondary combustion chamber. A loose hood is arranged on the bottom of the burnout chamber to ensure smooth separation and transportation of materials. However, these types of boilers are often used to produce hot water or saturated steam, and thus cannot be applied to industrial heating or steam power generation systems that require higher levels of temperature and pressure.

Summary of the invention

In view of the deficiencies and shortcomings of the prior art, the present invention provides a horizontal circulating fluidized bed superheated steam boiler, which has a compact structure and fluidized combustion on the one hand, and high-quality superheated steam with high temperature and high pressure on the other hand.

The invention is achieved by the following technical solutions:

A horizontal circulating fluidized bed superheated steam boiler comprising a main combustion chamber consisting of a dense phase zone of a main combustion chamber and a dilute phase zone of a main combustion chamber, a secondary combustion chamber, a burnout chamber, a drum, a soda water outlet pipe, and a saturation a steam take-off pipe, a separator and a tail flue, a wind deflecting plate is arranged in a lower part of the main combustion chamber, a first water-cooling wall partition wall is arranged between the main combustion chamber and the auxiliary combustion chamber, and a section between the auxiliary combustion chamber and the burn-out chamber is provided The second water cold wall partition has a V-shaped ash hopper at the bottom of the auxiliary combustion chamber and the burnout chamber; the separator is connected to the burnout chamber through the connecting passage, and the separator can be arranged one or two according to the size of the boiler; The channel is connected to the returning device; the returning device is respectively connected with the returning port and the bottom of the V-shaped ash hopper; the low temperature economizer, the high temperature economizer and the air preheater, the low temperature economizer and the high temperature province are arranged in the tail flue The coalers are connected in series. The horizontal circulating fluidized bed superheated steam boiler arranges a multi-screen high-temperature radiation superheater in a dilute phase region of a main combustion chamber, and a low-temperature convection superheater in a secondary combustion chamber; the low-temperature convection superheater passes through a saturated steam extraction pipe and The drum is connected; the high temperature radiation superheater is connected to the low temperature convection superheater through the steam communication pipe; the water spray desuperheater is arranged on the steam communication pipe; the high temperature radiation superheater of each screen is composed of the inlet header box, the outlet header box and the superheater tube; The low temperature convection superheater consists of an upper header, a lower header and a serpentine tube.

The technical feature of the present invention is further that: the distance S1 between the tube screens in the multi-screen high-temperature radiation superheater is 0.6-2.0 m; the distance S1 is 0.6-2.0 m; the pitch between the superheater tubes S2 and the tube The ratio of the diameter D1 is 1.25 to 1.50. The upper part of the low-temperature convection superheater is arranged in a stepped manner, and is inclined downward from the first water-cooling wall partition wall 8 toward the second water-cooling wall partition wall 28; the transverse pitch S3 between the serpentine tubes is 60 ～ 150mm, longitudinal pitch S4 is 50 ~ 120mm.

Compared with the prior art, the invention has the following advantages and outstanding effects: 1 Compared with the conventional horizontal circulating fluidized bed boiler, high temperature and high pressure steam can be produced. Thanks to the water spray desuperheater, the superheater outlet steam temperature can be precisely controlled. 2 The high temperature radiant superheater in the main combustion chamber and the low temperature convection superheater in the sub-combustion chamber are arranged in series, making full use of the opposite characteristics of the radiant superheater and the convective superheater outlet steam temperature with load change, the steam temperature regulation characteristics are good, and it is easy to control temperature. 3 convection superheaters with horizontal and stepped arrangement in the combustion chamber fully adapt to the gas-solid flow outside the pipe, which is beneficial to the balance of material circulation and heat transfer. The invention is based on a conventional horizontal circulating fluidized bed boiler, and a unique superheater system is arranged. The invention not only inherits the fuel adaptability of the horizontal circulating fluidized bed boiler, but also has the advantages of high fuel adaptability, desulfurization and denitration in the furnace, and high temperature and high pressure steam in the "pot" aspect. The invention is particularly suitable for applications requiring high quality steam utilization.

DRAWINGS

1 is a schematic view showing the structure principle of a horizontal circulating fluidized bed superheated steam boiler provided by the present invention.

Figure 2 is a schematic diagram of a boiler steam water system.

3a and 3b are schematic views of a stepped arrangement of a low temperature convection superheater tube bundle.

Figure 4 is a schematic diagram of a high temperature radiation superheater tube screen.

Figure 5 is a top plan view of a horizontal circulating fluidized bed superheated steam boiler in which a separator is disposed.

Figure 6 is a top plan view of a horizontal circulating fluidized bed superheated steam boiler in which two separators are arranged.

In the figure: 1-winding plate; 2-main combustion chamber dense phase zone; 3-fuel feeding device; 4-spray water desuperheater; 5-steam communication pipe; 6-high temperature radiation superheater; 7-main combustion Room dilute phase zone; 8 - first water wall partition; 9 - down pipe; 10 - soda Outlet tube; 11-superheated steam outlet; 12-saturated steam outlet pipe; 13-drum; 14-sub-combustion chamber; 15-burning chamber; 16-connecting passage; 17-separator; 18-horizontal flue; -tail flue; 20-high temperature economizer; 21-low temperature economizer; 22-air preheater; 23-flue gas outlet; 24-return port; 25-returner; 26-V-shaped hopper ;27-return channel;28-second water wall partition;29-back wall water wall; 30-low temperature convection superheater; 31-water spray desuperheating valve; 32-decreasing water pipe; 33-uplink box ; 34 - serpentine tube; 35 - lower header; 36 - inlet header; 37 - outlet header; 38 - superheater tube.

detailed description

The specific embodiments and working processes of the present invention are further described below in conjunction with the accompanying drawings.

1 is a schematic view showing the structure of a horizontal circulating fluidized bed superheated steam boiler provided by the present invention, which comprises a main combustion chamber consisting of a dense phase zone 2 of the main combustion chamber and a rare phase zone 7 of the main combustion chamber, and a secondary combustion. a chamber 14, a burnout chamber 15, a drum 13, a soda water outlet pipe 10, a saturated steam take-off pipe 12, a separator 17 and a tail flue 19, and a wind deflecting plate 1, a main combustion chamber and a sub-combustion are arranged in a lower portion of the main combustion chamber. There is a first water wall partition 8 between the chambers 14, a second water wall partition 28 between the sub-chamber 14 and the burnout chamber 15, and a V-shaped hopper 26 at the bottom of the sub-chamber 14 and the burn-out chamber 15. The separator 17 is connected to the burnout chamber 15 through the connecting passage 16, and one or two can be arranged; the lower portion of the separator 17 is connected to the return feeder 25 through the return passage 27; the return feeder 25 and the return port 24 and V, respectively The bottom of the ash hopper 26 is connected; a low temperature economizer 21, a high temperature economizer 20 and an air preheater 22 are arranged in the tail flue 19, and the low temperature economizer 21 and the high temperature economizer 22 are connected in series. A multi-screen high temperature radiant superheater 6 is disposed in the main combustion chamber lean phase zone 7, and a low temperature convection superheater 30 is disposed in the secondary combustion chamber 14. The low temperature convection superheater 30 is connected to the drum 13 through a saturated steam outlet pipe 12; the high temperature radiation superheater 6 is connected to the low temperature convection superheater 30 through a steam communication pipe 5; and the water spray desuperheater 4 is disposed on the steam communication pipe 5.

2 is a schematic view of a steam circulating water system of a horizontal circulating fluidized bed superheated steam boiler according to the present invention. The boiler feed water is sequentially introduced into the drum 13 through the low temperature economizer 21 and the high temperature economizer 20, and then distributed to the main combustion chamber by the downcomer 9. The sub-combustion chamber 14 and the water-cooling wall in the burn-out chamber 15. The boiler feed water absorbs heat in the water wall to form a steam-water mixture, and the steam-water mixture is led to the drum 13 by the steam-water outlet pipe 10. The steam-water mixture passes through the steam-water separation device inside the drum, and the hot water portion is further sent to the downcomer 9 to participate in the circulation, and the saturated steam portion is then led to the low-temperature convection superheater 30 by the saturated steam extracting pipe 12 to continue to absorb heat and reach overheating. State, forming superheated steam. The superheated steam is then led by the steam communication pipe 5 to the high temperature radiant superheater 6 to continue to absorb heat until the design parameters are reached, and the boiler is taken out from the superheated steam outlet 11. The superheater desuperheating water is taken from the boiler feed water, and is led to the water spray desuperheater 4 via the desuperheating water pipe 32. The superheated steam achieves the purpose of superheated steam cooling by mixing with the desuperheated water in the water spray desuperheater 4. A water spray desuperheating regulating valve 31 is disposed on the desuperheating water pipe 32, and the amount of desuperheating water entering the water sprinkler 4 is controlled by adjusting the opening degree of the water spray desuperheating regulating valve 31, thereby realizing temperature adjustment and control. .

3a and 3b are schematic diagrams of a stepped arrangement of a low temperature convection superheater tube bundle. The low temperature convection superheater 30 is composed of an upper header 33, a lower header 35 and a serpentine tube 34; the upper part of the low temperature convection superheater is arranged in a stepped manner, from The water-cooling wall partition wall 8 is arranged in a stepped downward direction toward the second water-cooling wall partition wall 28; the horizontal pitch S3 between the serpentine tubes 34 is 60-150 mm, and the longitudinal pitch S4 is 50-120 mm. The low temperature convection superheater welcomes the flow direction of the flue gas, and the step is inclined to facilitate the secondary combustion. The high concentration material in the chamber 14 near the burnout chamber 15 flows smoothly (the concentration of the material near the burnout chamber is high due to the centrifugal action of the particles flowing through the inverted U-shaped passage between the main combustion chamber and the burnout chamber).

4 is a schematic view of a high temperature radiant superheater tube panel, and each of the high temperature radiant superheaters 6 is composed of an inlet header 36, an outlet header 37 and a superheater tube 38. Each boiler can be arranged with multiple screens according to requirements. In this example, 3 screens are arranged, and the distance S1 between the tube screens is 0.6-2.0 m; the ratio of the pitch S2 of the superheater tubes 38 to the tube diameter D1 is 1.25 to 1.50. .

Figures 5 and 6 show schematic views of the embodiment of a horizontal circulating fluidized bed superheated steam boiler with one and two separators, respectively. When the boiler evaporation is 3~10t/h, a separator should be arranged; when the boiler evaporation is 10~20t/h, it is better to arrange one or two separators according to the actual situation; when the boiler evaporation is greater than 20t/ When h, it is advisable to arrange two separators.

The working process of the present invention is as follows:

The fuel is fed from the fuel feeding device 3, and the air supporting the combustion is sent from the air distribution plate 1 through the air preheater 22, and the fuel is sequentially in the dense phase region of the main combustion chamber 2, the dilute phase region of the main combustion chamber 7, and the secondary combustion. The chamber 14 and the burnout chamber 15 are combusted, and the flue gas carrying the particulate matter generated by the combustion is separated by the separator 17, and the flue gas enters the tail flue 19 through the separator and the horizontal flue 18, and sequentially flows through the high-temperature economizer 20, The low temperature economizer 21 and the air preheater 22 exit the boiler via the flue gas outlet 23. When the particulate matter in the flue gas flows through the V-shaped ash hopper 16 between the secondary combustion chamber 14 and the burnout chamber 15, due to the inertial separation, some particulate materials are separated and deposited in the V-shaped ash hopper, without being separated. The particulate material continues to flow into the separator 17 as the flue gas continues to be further separated in the separator 17. The separated particulate material of the separator 17 flows into the returning device 25 along the return passage 27, merges with the particulate material flowing from the V-shaped ash hopper 26 into the returning device 25, and all the materials finally pass through the returning device 25 through the returning port. 24 is sent back to the dense phase zone 2 of the main combustion chamber to complete a material cycle. On the one hand, the particulate material circulation can circulate and burn unburned carbon particles to improve the combustion efficiency. On the other hand, the concentration of the particulate material in the main combustion chamber and the secondary combustion chamber can be increased, and the higher material concentration is beneficial to improve the arrangement in the main combustion chamber. And the heat transfer coefficient of the flue gas in the sub-combustion chamber superheater.

Claims

A horizontal circulating fluidized bed superheated steam boiler comprising a main combustion chamber (14) consisting of a dense phase zone (2) of a main combustion chamber and a dilute phase zone (7) of a main combustion chamber, and a burnout chamber (15), a drum (13), a steam-water outlet pipe (10), a saturated steam outlet pipe (12), a separator (17), and a tail flue (19), and a wind deflector is arranged at a lower portion of the main combustion chamber (1) a first water wall partition (8) is provided between the primary combustion chamber and the secondary combustion chamber (14), and a second water wall partition is provided between the secondary combustion chamber (14) and the burnout chamber (15) (28) a V-shaped ash hopper (26) is provided at the bottom of the secondary combustion chamber (14) and the burnout chamber (15); the separator (17) is connected to the burnout chamber (15) through the connection passage (16) The separator (17) is arranged one or two; the lower part of the separator (17) is connected to the return feeder (25) through the return passage (27); the return feeder (25) is respectively connected to the return port (24) and V The bottom of the ash hopper (26) is connected; the low temperature economizer (21), the high temperature economizer (20) and the air preheater (22), the low temperature economizer (21) and the tail flue (19) are arranged; The high-temperature economizer (22) is connected in series, and is characterized in that a multi-screen high-temperature radiation superheater (6) is arranged in the dilute phase region (7) of the main combustion chamber, and a low temperature is arranged in the sub-combustion chamber (14). a superheater (30); a low temperature convection superheater (30) connected to the drum (13) through a saturated steam outlet pipe (12); a high temperature radiant superheater (6) through a steam communication pipe (5) and a low temperature convection superheater ( 30) connected; a water spray desuperheater (4) is arranged on the steam communication pipe (5); each screen high temperature radiation superheater (6) is connected to the inlet header (36), the outlet header (37) and the superheater tube (38) The composition; the low temperature convection superheater (30) consists of an upper header (33), a lower header (35) and a serpentine tube (34).
A horizontal circulating fluidized bed superheated steam boiler according to claim 1, wherein: the distance S1 between the tube panels in the multi-screen high-temperature radiation superheater is 0.6 to 2.0 m; and the superheater tube (38) The ratio of the inter-tube pitch S2 to the tube diameter D1 is 1.25 to 1.50.
A horizontal circulating fluidized bed superheated steam boiler according to claim 1, wherein said upper portion of said low temperature convection superheater (30) is arranged in a stepped manner from said first water wall partition wall 8 The direction of the second water wall partition wall 28 is inclined downwardly in a stepwise manner; the transverse pitch S3 between the serpentine tubes (34) is 60-150 mm, and the longitudinal pitch S4 is 50-120 mm.