CN114562877A

CN114562877A - High-temperature molten salt furnace with two-stage burners

Info

Publication number: CN114562877A
Application number: CN202210113591.8A
Authority: CN
Inventors: 周昊; 谢碧达; 马伟伟; 朱义凡
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2022-01-30
Filing date: 2022-01-30
Publication date: 2022-05-31
Anticipated expiration: 2042-01-30
Also published as: CN114562877B

Abstract

The invention discloses a high-temperature molten salt furnace with two stages of burners, which comprises a furnace body, and an outer coil, an inner coil, a primary burner and a secondary burner which are arranged in the furnace body; the outer coil and the inner coil are filled with molten salt, the first-stage burner is positioned in the center of the base, and the second-stage burners are positioned in the range of 1/4 on the upper part of the furnace body and are not less than two and are uniformly and symmetrically arranged along the radial direction; the secondary combustor is of a sleeve structure and comprises a main spray hole facing the inside of the inner coil, and an interlayer spray hole and a suction hole which are arranged between the outer coil and the inner coil. Through the introduction of second grade combustor to and intermediate layer orifice and suction hole, can realize the abundant burning of high temperature flue gas, when improving combustion efficiency, reducible high temperature nitrogen oxide generates, because the regulatory action of second grade combustor for molten salt temperature is controllable in the molten salt coil pipe, avoids appearing local high temperature, thereby realizes that molten salt furnace export molten salt temperature is above 590 ℃.

Description

High-temperature molten salt furnace with two-stage combustor

Technical Field

The invention belongs to the field of high-temperature molten salt furnaces, and particularly relates to a high-temperature molten salt furnace with two stages of combustors.

Background

At present, the temperature of molten salt at the outlet of a molten salt furnace is generally about 400 ℃, and the temperature of the molten salt at the outlet of more than 590 ℃ is difficult to realize. The temperature of the molten salt at the outlet is not high, on one hand, the unreasonable pipe arrangement efficiency of the molten salt furnace is not high; on the other hand, because the existing high-efficiency molten salt furnace generally adopts a long-flow design, but the radiation area range of the furnace is small, the convection area range is large, so that the tail-section smoke output is insufficient, and the molten salt temperature cannot be continuously increased.

In order to realize a high-temperature molten salt furnace, the following more representative molten salt furnace design scheme is presented at present.

(1) The Chinese patent with publication number CN 209726798U discloses a design form of a molten salt furnace with an integral cylindrical structure, which can realize outlet molten salt temperature of 550 ℃, and adopts a cylindrical integral structure, and comprises an inner-ring radiation coil pipe, an outer-ring convection coil pipe and a top coil pipe.

(2) The Chinese patent with publication number CN 203148032U discloses a high-efficiency coal-fired powder molten salt furnace, which is characterized in that a radiation furnace body with a radiation hearth and a convection furnace body with a convection hearth are connected through a convection flue.

Among the above-mentioned prior art, each has certain advantage and disadvantage to improving molten salt furnace outlet fused salt temperature, in above-mentioned (1), through the arrangement of radiation coil and convection coil, its advantage lies in, can make full use of behind the radiation heat transfer flue gas continue to convection coil heat transfer, improve the whole temperature of molten salt furnace, nevertheless from the practical perspective, under the normal condition, the molten salt furnace radiation area is less than the convection area, so inner circle radiation coil upper half radiation intensity begins to weaken, inner and outer coil pipe clamp layer convection current district flue gas and convection zone outer layer are exerted oneself and are further weakened, can't reach the purpose of continuing to promote the fused salt temperature. (2) In the middle, radiation zone and convection current district separation simplify the molten salt furnace structure, but connect the radiation convection furnace body through the convection current flue, reduced molten salt furnace efficiency, simultaneously because do not optimize combustion system and flue gas system, the pulverized coal burning produces higher concentration NOx, causes the atmosphere pollution.

Disclosure of Invention

In order to solve the problem of low temperature of fused salt at the outlet of a fused salt furnace, improve the combustion efficiency of the fused salt furnace and reduce the technical problem of NOx emission generated by combustion, the invention provides a high-temperature fused salt furnace with two stages of combustors, and the specific technical scheme is as follows:

a high temperature molten salt furnace having two stages of burners, the high temperature molten salt furnace comprising:

the burner comprises a top cover, a furnace body, a base, a secondary burner bracket, an outer coil, an inner coil, a primary burner, a secondary burner, a fuel replenishing pipe and an air distribution pipe;

the top cover, the furnace body and the base are sequentially and fixedly connected from top to bottom, and a combustion space is formed inside the top cover, the furnace body and the base; the secondary burner bracket is fixed on the furnace body;

the outer coil pipe and the inner coil pipe are both positioned in the furnace body, the upper end and the lower end of the outer coil pipe are respectively contacted with the top cover and the base, the inner coil pipe is positioned in the outer coil pipe, the lower end of the inner coil pipe is fixedly connected with the base, and a gap is reserved between the upper end of the inner coil pipe and the top cover; the outer coil pipe and the inner coil pipe are filled with molten salt;

the primary combustor is positioned in the center of the base;

the two secondary burners are positioned in the 1/4 range at the upper part of the furnace body, and are not less than two, and are uniformly and symmetrically arranged along the radial direction; one end of the secondary combustor is supported by the secondary combustor bracket;

The secondary combustor is of a sleeve structure and comprises three layers of an outer sleeve, a middle sleeve and an inner sleeve, the outer sleeve is positioned at one end, close to the inner coil, of the secondary combustor, the length of the outer sleeve is shorter than that of the middle sleeve and the length of the inner sleeve, and the outer sleeve is used for fixing the secondary combustor between gaps of the inner coil; the inner sleeve sequentially comprises a connecting section of a distribution pipe, a reducing pipe section, a constant section pipe section, a widening pipe section and a stable combustion pipe section along the radial direction of the furnace body inwards; the secondary combustor comprises a main spray hole facing the interior of the inner coil, and an interlayer spray hole and a suction hole which are positioned between the outer coil and the inner coil; the interlayer spray holes are through holes penetrating through the three layers of sleeves, and the suction holes are through holes penetrating through the middle sleeve and the inner sleeve; the suction holes are positioned in the equal-section pipe section;

the fuel replenishing pipe is inserted into the inner sleeve, and the air distribution pipe is communicated with the inner sleeve of the secondary combustor.

Further, the fuel replenishing pipe extends into the tail end of the constant-section pipe section of the inner sleeve; the air distribution pipe is connected with the tapered pipe section of the inner sleeve.

Furthermore, the number of the secondary burners is 4, and the secondary burners are uniformly distributed on the same cross section of the furnace body.

Further, the middle sleeve of the secondary combustor can move along the axial direction and rotate in the circumferential direction, the opening degree of the suction hole is controlled through the axial movement, and the opening degree of the interlayer spray hole is adjusted through the circumferential rotation.

Further, still the symmetry has seted up exhanst gas outlet on the furnace body, interior coil pipe entry and outer coil pipe entry are all passed the top cap sets up outwards, outer coil pipe export and interior coil pipe export are all passed the base sets up outwards.

Furthermore, the top cover and the furnace body are wrapped with heat insulation materials, so that the temperature loss is reduced.

The invention has the following beneficial effects:

(1) the high-temperature molten salt furnace adopts a two-stage combustion mode, the problem that the rear-section smoke output of the existing molten salt furnace is insufficient is solved, the waste heat of the primary combustor is efficiently utilized by introducing the secondary combustor to heat the fuel, meanwhile, the high-temperature smoke is mixed with air and the fuel and is sprayed into the primary radiation area and the secondary radiation area through the coil pipe gap to be fully combusted, and the mixed high-temperature smoke is sprayed into the coil pipe interlayer to be uniformly distributed in the interlayer along with the high-temperature smoke from top to bottom so as to be stably combusted.

(2) The secondary burner used in the invention can participate in the combustion of the primary radiation area and the secondary radiation area of the coil pipe interlayer at the same time through multi-point arrangement and special types.

(3) The interlayer spray holes of the secondary combustor are arranged between the inner coil pipe and the outer coil pipe of the molten salt furnace, the temperature of molten salt in the molten salt coil pipe is controllable due to the adjusting effect of the secondary combustor, and local high temperature is avoided, so that the temperature of molten salt at the outlet of the molten salt furnace is above 590 ℃, and meanwhile, air classification is formed due to the arrangement of the two-stage combustor at different standard layers, and the production of nitrogen oxides is further reduced.

Drawings

FIG. 1 is a schematic view showing an external structure of a high temperature molten salt furnace having two stages of burners according to the present invention;

FIG. 2 is a schematic view of a 1/4 cut-away view of the high temperature molten salt furnace of the present invention having a two-stage burner;

FIG. 3 is a top view of a burner arrangement;

FIG. 4 is a schematic view of a two-stage combustor burner configuration;

FIG. 5 is a partial cross-sectional view of a two-stage combustor burner configuration.

In the figure, a top cover 1, a furnace body 2, a base 3, a secondary combustor support 4, a primary combustor 5, an outer coil 6, an inner coil 7, a secondary combustor 8, a fuel replenishing pipe 9, an air distribution pipe 10, a primary radiation zone 11, a secondary radiation zone 12, a flue gas convection zone 13, a flue gas outlet 2-1 and an outer coil inlet 6-1, 6-2 parts of an outer coil outlet, 7-1 parts of an inner coil inlet, 7-2 parts of an inner coil outlet, 8-1 parts of an outer sleeve, 8-2 parts of a middle sleeve, 8-3 parts of an inner sleeve, 8-4 parts of interlayer spray holes, 8-5 parts of a suction hole, 8-6 parts of a main spray hole, 8-3-1 parts of a connecting section of a distribution pipe, 8-3-2 parts of a reducing pipe section, 8-3-3 parts of a pipe section with an equal section, 8-3-4 parts of a widening pipe section and 8-3-5 parts of a stable combustion pipe section.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and preferred embodiments, and the objects and effects of the present invention will become more apparent, it being understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

As shown in fig. 1 and 2, the high-temperature molten salt furnace with two-stage burners of the present invention includes a top cover 1, a furnace body 2, a base 3, a secondary burner support 4, an outer coil 6, an inner coil 7, a primary burner 5, a secondary burner 8, a fuel replenishing pipe 9, and a distributing pipe 10.

Wherein, from top to bottom, top cap 1, furnace body 2, base 3 link firmly in proper order, and the combustion space is constituteed to the inside of three. The furnace body 2 is also symmetrically provided with a flue gas outlet 2-1. The secondary burner mount 4 surrounds and is fixed to the furnace body 2. Outer coil pipe 6, interior coil pipe 7 all are located in

furnace body

2, and 6 upper ends of outer coil pipe link firmly with top cap 1, leave the clearance between lower extreme and base 3, interior coil pipe 7 is located inside the outer coil pipe 6, its lower extreme with base 3 links firmly, the upper end with leave the clearance between the top cap 1. The inner coil inlet 7-1 and the outer coil inlet 6-1 penetrate through the top cover 1 and are arranged outwards, and the outer coil outlet 6-2 and the inner coil outlet 7-2 penetrate through the base 3 and are arranged outwards. The outer coil 6 and the inner coil 7 are filled with molten salt.

The primary burner 5 is positioned at the center of the base 3, and the secondary burners 8 are positioned in the range of 1/4 at the upper part of the furnace body 2, and not less than two, 4 in the embodiment, are uniformly and symmetrically arranged along the radial direction, as shown in figure 3. The outer end of the secondary burner 8 is fixed on the secondary burner support 4.

As shown in fig. 3, the high-temperature molten salt furnace with two-stage burners of the present invention is divided into a first-stage radiation zone 11, a second-stage radiation zone 12, and a flue gas convection zone 13 according to the area division. Wherein, the first-stage radiation area 11 is positioned at the inner side of the inner coil 7 in the furnace body, and the first-stage combustor 5 burns to generate heat and exchanges heat with the inner coil 7 in a radiation manner. The secondary radiation zone 12 is located in the interlayer region between the inner coil 7 and the outer coil 6 in the furnace body, namely the secondary combustor 8 generates heat through combustion in the radiation heat exchange region between the interlayer of the inner coil and the outer coil. The flue gas convection zone 13 is the outer side of the outer coil 6 in the furnace body, and the high-temperature flue gas generated by the primary and secondary radiation zones and the convection heat exchange zone of the outer coil. Wherein, the primary combustor 5 is used for providing primary radiation area heat supply and high-temperature flue gas supply; the secondary combustor 8 is used for providing heat supplement for the primary radiation area, and the primary combustor is used for generating high-temperature flue gas to preheat natural gas, adjusting the air-fuel ratio and optimizing combustion.

The secondary combustor 8 is of a sleeve structure and comprises an outer sleeve 8-1, a middle sleeve 8-2 and an inner sleeve 8-3. The outer sleeve 8-1 is shorter than the middle sleeve 8-2 and the inner sleeve 8-3 in length and is located at one end of the secondary burner 8 close to the inner coil 7 for fixing the secondary burner 8 between the gaps of the inner coil 7. The inner sleeve 8-3 sequentially comprises an air distribution pipe connecting section 8-3-1, a reducing pipe section 8-3-2, an equal section pipe section 8-3-3, a widening pipe section 8-3-4 and a stable combustion pipe section 8-3-5 along the radial direction of the furnace body inwards, and is used for providing pressure difference to suck smoke and providing a mixing space.

The secondary combustor 8 comprises a main spray hole 8-6 facing the interior of the inner coil pipe 7, and an interlayer spray hole 8-4 and a suction hole 8-5 which are positioned between the outer coil pipe 6 and the inner coil pipe 7; and the interlayer spray hole 8-4 is positioned at the position of the secondary combustor 8 with a three-layer sleeve structure and is a through hole penetrating through the three-layer sleeve, the suction hole 8-5 is positioned at the position of only the middle sleeve 8-2 and the inner sleeve 8-3 and is a through hole penetrating through the middle sleeve 8-2 and the inner sleeve 8-3, and one end of the suction hole 8-5 close to the inner side is positioned at the equal-section pipe section 8-3-3 of the inner sleeve.

The air distribution pipe 10 is connected with a tapered pipe section 8-3-2 of an inner sleeve 8-3 of the secondary combustor and used for adjusting air distribution of the secondary combustor; the fuel replenishing pipe 9 is arranged in the middle of an inner sleeve 8-3 of the secondary combustor and extends into the tail section of the equal-section pipe section 8-3-3 to replenish fuel of the secondary combustor.

As shown in FIG. 5, the middle sleeve 8-2 of the secondary combustor 8 can move along the axial direction and rotate along the circumferential direction, and the opening degree of the suction hole 8-5 can be controlled through the axial movement, so that the smoke suction control is realized. The opening of the interlayer spray holes 8-4 is adjusted through circumferential rotation, so that the combustion of the secondary radiation zone 12 is controlled.

The working principle of the high-temperature molten salt furnace with the two-stage combustor is as follows:

the primary combustor 5 burns in the primary radiation area 11 to generate high-temperature flue gas, the high-temperature flue gas passes through the upper end of the primary radiation area 11 and is secondarily combusted by the secondary combustor 8, the high-temperature flue gas is blocked by the top cover 1 to enter the secondary radiation area 12, and the high-temperature flue gas is sucked by the suction holes 8-2-2 of the secondary combustor 8 and enters the equal-section pipe sections 8-3-3 of the secondary combustor 8.

In the secondary combustor 8, air is fed through the air distribution pipe 10, compressed and accelerated through the tapered pipe section 8-3-2, and differential pressure is generated by the uniform-section pipe section 8-3-3. A fuel supply pipe 9, centrally arranged to the inner sleeve 8-3 of the secondary burner 8, injects fuel, such as natural gas, into the end of the constant section pipe section 8-3-3.

The fuel is heated by high-temperature smoke which is sucked into the equal-section pipe section 8-3-3 through the suction hole 8-5 and is fully mixed with air, the mixture reaches the tail end of the gradually-widening pipe section 8-3-4, and the mixture is completely mixed and enters the stable-combustion pipe section 8-3-5. At the moment, the flue gas is divided into two parts, one part is sprayed into a secondary radiation area 12 between the inner coil 7 and the outer coil 6 through interlayer spray holes 8-4 of the secondary burner plate for combustion, and the other part is sprayed into the upper section of a primary radiation area 11 on the inner side of the inner coil 7 through main spray holes 8-6 of the secondary burner plate for combustion. Finally, the converged flue gas is circulated and then is discharged out of the furnace body 2 through the flue gas convection zone 13 and the flue gas outlet 2-1.

It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of the present invention, and is not intended to limit the invention, and although the invention has been described in detail with reference to the foregoing examples, it will be apparent to those skilled in the art that various changes in the form and details of the embodiments may be made and equivalents may be substituted for elements thereof. All modifications, equivalents and the like which come within the spirit and principle of the invention are intended to be included within the scope of the invention.

Claims

1. A high-temperature molten salt furnace with two-stage burners, comprising:

the device comprises a top cover (1), a furnace body (2), a base (3), a secondary combustor support (4), an outer coil (6), an inner coil (7), a primary combustor (5), a secondary combustor (8), a fuel replenishing pipe (9) and an air distribution pipe (10);

the top cover (1), the furnace body (2) and the base (3) are fixedly connected in sequence from top to bottom, and a combustion space is formed inside the top cover, the furnace body and the base; the secondary burner bracket (4) is fixed on the furnace body (2);

the outer coil (6) and the inner coil (7) are both positioned in the furnace body (2), the upper end and the lower end of the outer coil (6) are respectively contacted with the top cover (1) and the base (3), the inner coil (7) is positioned in the outer coil (6), the lower end of the inner coil is fixedly connected with the base (3), and a gap is reserved between the upper end of the inner coil and the top cover (1); the outer coil pipe (6) and the inner coil pipe (7) are filled with molten salt;

The primary combustor (5) is positioned in the center of the base (3);

the two secondary burners (8) are positioned in the 1/4 range at the upper part of the furnace body (2), and are not less than two, and are uniformly and symmetrically arranged along the radial direction; one end of the secondary combustor (8) is supported by the secondary combustor bracket (4);

the secondary combustor (8) is of a sleeve structure and comprises three layers of an outer sleeve (8-1), a middle sleeve (8-2) and an inner sleeve (8-3), wherein the outer sleeve (8-1) is positioned at one end, close to the inner coil (7), of the secondary combustor (8), and the length of the outer sleeve is shorter than that of the middle sleeve (8-2) and the inner sleeve (8-3) and is used for fixing the secondary combustor (8) between gaps of the inner coil (7); the inner sleeve (8-3) sequentially comprises an air distribution pipe connecting section (8-3-1), a reducing pipe section (8-3-2), a constant-section pipe section (8-3-3), a gradually widening pipe section (8-3-4) and a stable combustion pipe section (8-3-5) along the radial direction of the furnace body inwards; the secondary combustor (8) comprises a main spray hole (8-6) facing the interior of the inner coil (7), and an interlayer spray hole (8-4) and a suction hole (8-5) which are positioned between the outer coil (6) and the inner coil (7); the interlayer spray holes (8-4) are through holes penetrating through the three layers of sleeves, and the suction holes (8-5) are through holes penetrating through the middle sleeve (8-2) and the inner sleeve (8-3); and the suction holes (8-5) are positioned in the equal section pipe sections (8-3-4);

The fuel replenishing pipe (9) is inserted into the inner sleeve (8-3), and the air distribution pipe (10) is communicated with the inner sleeve (8-3) of the secondary combustor (8).

2. A high temperature molten salt furnace with two-stage burner according to claim 1, characterized in that the fuel replenishing pipe (9) extends into the end of the constant section pipe section (8-3-4) of the inner sleeve (8-3); the air distribution pipe (10) is connected with the tapered pipe section (8-3-5) of the inner sleeve (8-3).

3. A high temperature molten salt furnace with two stages of burners according to claim 1, wherein said two stages of burners (8) are 4 and are uniformly distributed on the same cross section of the furnace body.

4. A molten salt furnace having two stages of burners according to claim 1, wherein the middle sleeve (8-2) of the secondary burner (8) is axially movable and circumferentially rotatable, the opening degree of the suction hole (8-5) is controlled by the axial movement, and the opening degree of the sandwich nozzle hole (8-4) is adjusted by the circumferential rotation.

5. The high-temperature molten salt furnace with the two-stage combustor according to claim 1, wherein a flue gas outlet (2-1) is further symmetrically formed in the furnace body (2), the inner coil inlet (7-1) and the outer coil inlet (6-1) both penetrate through the top cover (1) and are arranged outwards, and the outer coil outlet (6-2) and the inner coil outlet (7-2) both penetrate through the base (3) and are arranged outwards.

6. The high-temperature molten salt furnace with the two-stage combustor according to claim 1, wherein the top cover (1) and the furnace body (2) are wrapped with heat insulation materials to reduce temperature loss.