Combined type grading heat exchanger

Abstract

The utility model provides a combined type grading heat exchanger which comprises a flue gas inlet pipe, a first-stage heat exchanger, an electric dust removal device, a second-stage heat exchanger, a heat exchanger communicating pipe and a flue gas outlet pipe, the flue gas inlet pipe and the flue gas outlet pipe are respectively connected with two ends of the electric dust removal device, the first-stage heat exchanger is arranged on the flue gas inlet pipe, and the second-stage heat exchanger is arranged on the heat exchanger communicating pipe. The secondary heat exchanger is arranged on the flue gas outlet pipe, the primary heat exchanger comprises a heat exchange pipe sleeve, a first water inlet and a first water outlet, the heat exchange pipe sleeve is arranged on the periphery of the flue gas inlet pipe, and the first water inlet and the first water outlet are formed in the heat exchange pipe sleeve; the secondary heat exchanger comprises a snakelike heat exchange pipe, a second water inlet and a second water outlet, and the snakelike heat exchange pipe is arranged in the flue gas outlet pipe. The utility model aims to solve the problem that the existing heat exchanger for coal-fired flue gas is difficult to consider energy conservation and safety at the same time.

Description

Technical Field

[0001] The utility model belongs to the technical field of power plant equipment, and specifically relates to a combined graded heat exchanger. Background Art

[0002] The boiler ultra-clean emission system is usually equipped with a heat exchanger before the electrostatic precipitator. By absorbing the exhaust heat from the air preheater outlet, the inlet flue gas temperature of the electrostatic precipitator is reduced to 90°C, and the circulating water temperature is increased from 70°C to above 100°C. The reheater at the chimney inlet heats the flue gas at the absorption tower outlet, so that the chimney exhaust flue gas temperature is increased to 70-80°C, achieving the chimney whitening effect. Since the heat exchanger has been operating near the acid dew point for a long time, due to uneven flow field distribution, low-temperature corrosion, high-ash flue gas wear and other reasons, the heat exchanger leaks seriously, and a large number of heat exchangers are facing failure transformation. Common transformation ideas include H-type fin tube heat exchangers, integral spiral fin tube heat exchangers, vacuum heat pipe heat exchangers and other solutions. Each solution has its own advantages and disadvantages, and it is often difficult to balance energy saving and safety. Utility Model Content

[0003] In view of the above-mentioned technical problems, the utility model provides a combined graded heat exchanger to solve the problem that the existing heat exchangers for coal-fired flue gas are difficult to balance energy saving and safety. The combined graded heat exchanger can better ensure the operation of the electrostatic precipitator and improve energy utilization.

[0004] The utility model discloses a combined graded heat exchanger, comprising a flue gas inlet pipe, a primary heat exchanger, an electrostatic precipitator, a secondary heat exchanger, a heat exchanger connecting pipe and a flue gas outlet pipe, wherein the flue gas inlet pipe and the flue gas outlet pipe are respectively connected to two ends of the electrostatic precipitator, the primary heat exchanger is arranged on the flue gas inlet pipe, and the secondary heat exchanger is arranged on the flue gas outlet pipe. The primary heat exchanger comprises a heat exchange tube sleeve, a first water inlet and a first water outlet, the heat exchange tube sleeve is arranged on the outer periphery of the flue gas inlet pipe, the heat exchange tube sleeve is provided with the first water inlet and the first water outlet, the secondary heat exchanger comprises a serpentine heat exchange tube, a second water inlet and a second water outlet, the serpentine heat exchange tube is built in the flue gas outlet pipe, the two ends of the serpentine heat exchange tube respectively extend out of the flue gas outlet pipe to form the second water inlet and the second water outlet, and the heat exchanger connecting pipe is respectively connected to the second water outlet and the first water inlet.

[0005] Furthermore, there are multiple flue gas inlet pipes, multiple electrostatic precipitators and multiple flue gas outlet pipes, and the multiple flue gas inlet pipes, multiple electrostatic precipitators and multiple flue gas outlet pipes are arranged in one-to-one correspondence.

[0006] Furthermore, the combined graded heat exchanger further comprises a water inlet pipe and a water outlet pipe, wherein the water inlet pipe is connected to the second water inlet, and the water outlet pipe is connected to the first water outlet.

[0007] When the combined graded heat exchanger is performing the cooling and dust removal operation of the coal-fired flue gas, the first-stage heat exchanger performs preliminary cooling of the coal-fired flue gas, and the coal-fired flue gas after preliminary cooling enters the electrostatic precipitator for dust removal. The coal-fired flue gas after dust removal is cooled for a second time by the second-stage heat exchanger, and two-stage heat exchange is realized by connecting the heat exchanger connecting pipe. Through the first-stage heat exchanger, the inlet flue gas temperature of the electrostatic precipitator can be reduced to 100-110°C, and through the second-stage heat exchanger, the outlet flue gas temperature of the electrostatic precipitator can be reduced to 85-90°C. The first-stage heat exchanger usually adopts a heat exchanger sleeve to ensure that when the system leaks, the heat exchanger and the electrostatic precipitator will not be blocked by dust, the load exceeds the limit, etc. The first-stage heat exchanger only needs to control the designed outlet flue gas temperature at 100-110°C to avoid the excessive design of the heat exchange area causing the original steel structure to exceed the load limit, and reduce the difficulty of project implementation. The secondary heat exchanger uses serpentine heat exchange tubes to achieve better cooling effect. The secondary heat exchanger is designed in the low ash environment at the outlet of the electrostatic precipitator, and the risk of ash blockage and equipment overload in the event of leakage is extremely low. Through graded design, the advantages of different types of heat exchanger technologies can be organically combined to achieve better energy saving and safety improvement effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0009] Figure 1 It is a structural schematic diagram of a combined staged heat exchanger. DETAILED DESCRIPTION

[0010] The utility model discloses a combined grading heat exchanger, which can better ensure the operation of an electric dust removal device and improve energy utilization rate.

[0011] The following will be combined with the drawings in the utility model to clearly and completely describe the technical solution in the utility model. Obviously, what is described is only a part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the utility model.

[0012] See also Figure 1As shown, the utility model provides a combined graded heat exchanger, comprising a flue gas inlet pipe 1, a primary heat exchanger 2, an electrostatic precipitator 5, a secondary heat exchanger 7, a heat exchanger connecting pipe 4 and a flue gas outlet pipe 8, wherein the flue gas inlet pipe 1 and the flue gas outlet pipe 8 are respectively connected to the two ends of the electrostatic precipitator 5, the primary heat exchanger 2 is arranged on the flue gas inlet pipe 1, the secondary heat exchanger 7 is arranged on the flue gas outlet pipe 8, the primary heat exchanger 2 comprises a heat exchange pipe sleeve 3, a first water inlet and a first water outlet, and the The heat exchange tube sleeve 3 is arranged on the outer periphery of the flue gas inlet pipe 1, and the first water inlet and the first water outlet are arranged on the heat exchange tube sleeve 3. The secondary heat exchanger 7 includes a serpentine heat exchange tube 6, a second water inlet and a second water outlet. The serpentine heat exchange tube 6 is built in the flue gas outlet pipe 8, and the two ends of the serpentine heat exchange tube 6 respectively extend out of the flue gas outlet pipe 8 to form the second water inlet and the second water outlet. The heat exchanger connecting pipe 4 is respectively connected to the second water outlet and the first water inlet.

[0013] The flue gas inlet pipe 1, the electrostatic precipitator 5 and the flue gas outlet pipe 8 are all multiple, and the multiple flue gas inlet pipes 1, the multiple electrostatic precipitator 5 and the multiple flue gas outlet pipes 8 are arranged in a one-to-one correspondence.

[0014] The combined graded heat exchanger further includes a water inlet pipe and a water outlet pipe, wherein the water inlet pipe is connected to the second water inlet, and the water outlet pipe is connected to the first water outlet.

[0015] When the combined graded heat exchanger is performing the cooling and dust removal operation of the coal-fired flue gas, the primary heat exchanger 2 performs preliminary cooling of the coal-fired flue gas, and the coal-fired flue gas after the preliminary cooling enters the electrostatic precipitator 5 for dust removal. The coal-fired flue gas after dust removal is subjected to secondary cooling by the secondary heat exchanger 7, and the two-stage heat exchange is realized through the heat exchanger connecting pipe 4. Through the primary heat exchanger 2, the inlet flue gas temperature of the electrostatic precipitator 5 can be reduced to 100-110°C, and through the secondary heat exchanger 7, the outlet flue gas temperature of the electrostatic precipitator 5 can be reduced to 85-90°C. The primary heat exchanger 2 usually adopts a heat exchanger sleeve 3 to ensure that when the system leaks, the heat exchanger and the electrostatic precipitator 5 will not be blocked by ash, the load exceeds the limit, etc. The primary heat exchanger 2 only needs to control the designed outlet flue gas temperature at 100-110°C to avoid the excessive load of the original steel structure caused by the excessive design of the heat exchange area, and reduce the difficulty of project implementation. The secondary heat exchanger 7 uses a serpentine heat exchange tube 6 to achieve a better cooling effect. The secondary heat exchanger 7 is designed in a low-ash environment at the outlet of the electrostatic precipitator 5, and the risks of ash blockage and equipment overload in the event of leakage are extremely low. Through hierarchical design, the advantages of different types of heat exchanger technologies can be organically combined to achieve better energy saving and safety improvement effects.

[0016] The above contents are further detailed descriptions of the present invention in combination with specific preferred implementations, and the specific implementation of the present invention cannot be considered to be limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A combined staged heat exchanger, characterized in that: The invention comprises a flue gas inlet pipe, a primary heat exchanger, an electrostatic precipitator, a secondary heat exchanger, a heat exchanger connecting pipe and a flue gas outlet pipe, wherein the flue gas inlet pipe and the flue gas outlet pipe are respectively connected to two ends of the electrostatic precipitator, the primary heat exchanger is arranged on the flue gas inlet pipe, and the secondary heat exchanger is arranged on the flue gas outlet pipe, the primary heat exchanger comprises a heat exchange tube sleeve, a first water inlet and a first water outlet, the heat exchange tube sleeve is arranged on the outer periphery of the flue gas inlet pipe, the heat exchange tube sleeve is provided with the first water inlet and the first water outlet, the secondary heat exchanger comprises a serpentine heat exchange tube, a second water inlet and a second water outlet, the serpentine heat exchange tube is built in the flue gas outlet pipe, the two ends of the serpentine heat exchange tube respectively extend out of the flue gas outlet pipe to form the second water inlet and the second water outlet, and the heat exchanger connecting pipe is respectively connected to the second water outlet and the first water inlet.

2. A combined staged heat exchanger according to claim 1, characterized in that: There are multiple flue gas inlet pipes, multiple electrostatic precipitators and multiple flue gas outlet pipes, and the multiple flue gas inlet pipes, multiple electrostatic precipitators and multiple flue gas outlet pipes are arranged in a one-to-one correspondence.

3. A combined staged heat exchanger according to claim 1, characterized in that: The combined graded heat exchanger further includes a water inlet pipe and a water outlet pipe, wherein the water inlet pipe is connected to the second water inlet, and the water outlet pipe is connected to the first water outlet.

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