Solid-solid heat exchange device startup protection device and use method thereof and heat exchange device

Abstract

The present invention discloses a solid-solid heat exchange device startup protection device, including a protection device heating pipe, a superheated steam inlet pipe, a mixing header, an evaporation heating surface pipe outlet and an evaporation heating surface pipe inlet; the protection device heating pipe is arranged in the mixing header, one end of the protection device heating pipe is connected to the superheated steam inlet pipe outside the mixing header, and the protection device heating pipe is provided with at least one small hole for discharging steam; the mixing header is provided with an evaporation heating surface pipe outlet and an evaporation heating surface pipe inlet, the evaporation heating surface pipe outlet is arranged above the mixing header, and the evaporation heating surface pipe inlet is arranged below the mixing header. The device has a simple structure, reliable performance, no pipe burst, greatly reduced cost, reduced energy consumption, and reduced mechanical failure points. The present invention also provides a method for using the solid-solid heat exchange device startup protection device, before starting, high-temperature steam is introduced from the side to establish a heat exchanger water circulation. The method is simple, feasible, safe and reliable.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchange equipment, and in particular to a device for protecting a heat exchange device when the heat exchange device is started and the heat exchange device. Background Art

[0002] At present, the cooling process for high-temperature solid block and granular materials (such as high-temperature sintered ore and pelletized ore, hereinafter referred to as "high-temperature materials") in China mainly adopts belt air coolers, ring air coolers or vertical air coolers for cooling.

[0003] The dusty hot flue gas used to cool the high-temperature materials then enters the waste heat boiler to produce hot water or low-parameter steam. The heat recovery system is complex, the air leakage rate is high, the sensible heat recovery efficiency of the high-temperature materials is low, and the operation and maintenance costs are high.

[0004] In view of the above situation, a vertical solid heat exchange waste heat recovery device is now used to recover heat by allowing the high-temperature material to pass through the superheater, evaporator and economizer arranged from top to bottom in sequence to solve the above problems existing in the high-temperature material waste heat recovery system in the prior art.

[0005] The vertical solid heat exchange waste heat recovery device is an important part of the entire smelting process, and the safety, continuity and stability of its operation are crucial. Due to the solid-solid heat exchange of high-temperature materials: high material temperature, high heat flux density, high thermal conductivity and other characteristics, it is easy to cause the heating surface of the superheater that exchanges heat with it to be suddenly heated, the metal wall temperature of the local heating surface to overheat, the heating surface to be damaged, and the overall operation of the boiler to be affected.

[0006] Reference Figure 1 In order to improve the above problem, a solution of adding an evaporator before the superheater 2 is shown. The added evaporator is the primary evaporator 1, and the original evaporator is the secondary evaporator 4. The primary evaporator 1 and the secondary evaporator 4 are respectively provided with a primary evaporator outlet header 1b and a secondary evaporator outlet header 4a, which are respectively connected to the steam drum 5 through pipelines, and the liquid water in the steam drum 5 is respectively transported to the primary evaporator 1 and the secondary evaporator 4 through pipelines.

[0007] The inlet end of the economizer comes from the water supply operation console, and the outlet end is connected to the steam drum, and enters the primary evaporator 1 and the secondary evaporator 4 through the downcomer. The steam-water mixture generated after heating by the primary evaporator 1 and the secondary evaporator 4 enters the steam drum 5, and the saturated steam separated in the steam drum 5 enters the superheater 2 through the pipeline. The steam heated by the superheater 2 enters the steam network or steam turbine for power generation.

[0008] In this way, by adding a first-stage evaporator 1 in the area of ​​higher temperature field, steam can be generated as quickly as possible to protect the superheater 2; at the same time, the superheater 2 is arranged in the area of ​​lower temperature field, which can also well protect the superheater 2.

[0009] This existing conventional water circulation flow mode does not cause any problem for conventional boilers, but the water circulation is slow to establish and cannot be well adapted to waste heat recovery boilers in the specific environment of solid-solid heat exchange of high-temperature materials.

[0010] The above improved structure or such technical enlightenment appears in the following patents:

[0011] 1. High-temperature solid heat recovery waste heat boiler and waste heat recovery method, authorization announcement number CN 104048284A, authorization announcement date 2014.09.17;

[0012] 2. Waste heat boiler with protective evaporator, authorization announcement number CN 206648007 U, authorization announcement date 2017.11.17;

[0013] 3. A waste heat boiler flue gas denitrification device, authorization announcement number CN 209549128 U, authorization announcement date 2019.10.29.

[0014] Unfortunately, the above improved structure still has some shortcomings. Taking a certain type of solid-solid heat exchange high-temperature waste heat recovery boiler adopting the improved structure as an example, the following problems are prone to occur:

[0015] (1) The boiler starts up slowly, and the water circulation on the working medium side of the boiler is not easy to establish. The enthalpy of saturated water at normal pressure is 417 kj / kg, the enthalpy of saturated steam is 2676 kj / kg, and the latent heat of vaporization is 2259 kj / kg. That is, to turn water into steam, a large amount of heat needs to be absorbed. According to the heat transfer coefficient of 55W / M2℃, it takes about 10 minutes to generate steam, and then the water circulation is slowly established. There is no problem for conventional boilers, but the water circulation is slow to establish, and it cannot adapt well to the waste heat boiler in the specific environment of high-temperature material solid-solid heat exchange.

[0016] (2) Before the water circulation is established, the medium in the evaporator heat exchange tube is in a static state. Since the outside of the evaporator heat exchange tube is solid-solid heat exchange, the heat flux density is very large. For the evaporation heating surface of the evaporator heat exchange tube, its heat load is greater than 6*10^6W / m2, so film boiling occurs, resulting in an increase in the temperature of the evaporation heating surface tube wall and a tube burst accident. For the superheater heating surface, since the water circulation is not established, there is no steam circulation cooling in the superheater heat exchange surface tube, the heat flux density outside the tube is large, and there is no medium cooling it in the tube, which can easily cause the tube wall temperature to rise to more than 650℃. It is difficult for us to find heat exchange surface tubes that can adapt to this temperature. Even if we can find it, it will be very expensive.

[0017] (3) To overcome problems (1) and (2), a hot water circulation pump is used to force circulation, which increases power consumption. At the same time, when the equipment fails, it will cause water circulation to stagnate, thus causing a pipe burst accident. Summary of the invention

[0018] The present invention aims to provide a solid-solid heat exchange device startup protection device and a method for using the same, and a heat exchange device, and is used to solve the technical problem that when the existing solid-solid heat exchange high-temperature waste heat recovery boiler processes high-temperature materials:

[0019] (1) Slow water circulation establishment leads to slow startup;

[0020] (2) Pipe burst accidents are more likely to occur, and the material has high requirements for heat resistance. It is difficult to find suitable materials or the cost is very high;

[0021] (3) The use of hot water circulation pumps for forced circulation increases power consumption. At the same time, equipment failure will cause water circulation stagnation, thus causing pipe burst accidents.

[0022] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0023] Provided is a solid-solid heat exchange device startup protection device, comprising a protection device heating pipe, a superheated steam introduction pipe, a mixing header, an evaporation heating surface pipe outlet and an evaporation heating surface pipe inlet;

[0024] The protection device heating tube is arranged in the mixing header, one end of the protection device heating tube is connected to the superheated steam inlet pipe outside the mixing header, and at least one small hole for discharging steam is arranged on the protection device heating tube; the mixing header is provided with an evaporation heating surface tube outlet and an evaporation heating surface tube inlet, the evaporation heating surface tube outlet is arranged above the mixing header, and the evaporation heating surface tube inlet is arranged below the mixing header.

[0025] Furthermore, there are a plurality of small holes, which are evenly and densely distributed on the heating tube of the protection device.

[0026] The present invention also provides a method for using a solid-solid heat exchanger device startup protection device, wherein the solid-solid heat exchanger device startup protection device, before the heat exchanger device using the solid-solid heat exchanger device startup protection device is started, introduces high-temperature steam from the side, and enters the mixing header through the superheated steam introduction pipe and the protection device heating pipe; after the high-temperature steam enters the protection device heating pipe, it is sprayed into the mixing header through the small hole, mixed with the water in the mixing header, and releases heat to heat the water in the mixing header, generate steam, and establish a heat exchanger water circulation through the steam; then, after the high-temperature material contacts the heat exchanger and can continue the water circulation of the heat exchanger through the high-temperature material, the introduction of the high-temperature steam is stopped.

[0027] The present invention also provides a heat exchange device, comprising the above-mentioned solid-solid heat exchange device startup protection device; the evaporating heating surface tube outlet is connected to the heat exchange device inlet.

[0028] The present invention also provides another heat exchange device, including the solid-solid heat exchange device startup protection device, a primary evaporator and a secondary evaporator; the inlet of the primary evaporator is connected to the evaporation heating surface tube outlet of the solid-solid heat exchange device startup protection device, and the outlet of the secondary evaporator is connected to the evaporation heating surface tube inlet of the solid-solid heat exchange device startup protection device.

[0029] The present invention also provides another heat exchange device, including the solid-solid heat exchange device startup protection device, a primary evaporator and a secondary evaporator; the mixing header of the solid-solid heat exchange device startup protection device replaces the primary evaporator outlet header of the primary evaporator and the secondary evaporator outlet header of the secondary evaporator; each heating tube inlet of the primary evaporator is connected to the evaporation heating surface tube outlet; each heating tube outlet of the secondary evaporator is connected to the evaporation heating surface tube inlet.

[0030] The beneficial effects of the present invention are:

[0031] The solid-solid heat exchanger startup protection device has a simple structure and reliable performance. It can more effectively establish water circulation before the heat exchanger is started, thereby protecting the heat exchanger from tube burst. At the same time, it can also greatly reduce the temperature of the superheater, and ordinary carbon steel pipe manufacturing materials can be used, which greatly reduces the cost. It also saves the high-temperature circulation pump, reduces investment, reduces energy consumption, and reduces mechanical failure points.

[0032] The heat exchange device using the solid-solid heat exchange device startup protection device can be suitable for heat exchange in a specific environment of solid-solid heat exchange of high-temperature materials, and there is no longer a problem of pipe bursting.

[0033] When the heat exchanger is used for cooling sintered ore and pelletized ore and for waste heat recovery boilers, the heat exchanger works stably and no longer bursts when processing high-temperature materials. At the same time, the superheater temperature is greatly reduced, and ordinary carbon steel pipes can be used as manufacturing materials, which greatly reduces costs. It also saves high-temperature circulation pumps, reduces investment, reduces energy consumption, and reduces mechanical failure points.

[0034] The method for cooling sintered ore and pelletized ore and recovering waste heat by using the cooling and waste heat recovery boiler is simple, feasible, safe and reliable. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a partial structural diagram of an existing solid-solid heat exchange high-temperature waste heat recovery boiler, which only shows the primary evaporator 1, the primary evaporator outlet header 1b, the superheater 2, the secondary evaporator 4, the secondary evaporator outlet header 4a, the steam drum 5 and the hot water circulation pump 6 related to the present invention ；

[0036] Figure 2 It is a structural schematic diagram of a start-up protection device for a solid-solid heat exchange device;

[0037] Figure 3 is a structural schematic diagram of a heat exchange device, which adopts the solid-solid heat exchange device startup protection device;

[0038] Figure 4 It is a waste heat recovery boiler for cooling sintered ore and pelletized ore, and is a solid-solid heat exchange high-temperature waste heat recovery boiler. The waste heat recovery boiler uses the heat exchange device as the primary evaporator 1 and the secondary evaporator 4; the contents not related to the present invention are omitted in the figure;

[0039] The components include a primary evaporator (1), a primary evaporator outlet header (1b), a superheater (2), a start-up protection device (3), a protection device heating pipe (3a), a superheated steam inlet pipe (3b), a mixing header (3c), an evaporation heating surface pipe outlet (3e), an evaporation heating surface pipe inlet (3f), a secondary evaporator (4), a secondary evaporator outlet header (4a), a steam drum (5), and a hot water circulation pump (6). DETAILED DESCRIPTION

[0040] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. Examples of the embodiments are shown in the accompanying drawings, and the embodiments described with reference to the accompanying drawings are only exemplary and are only used to explain the present invention, rather than limiting the present invention.

[0041] The directions and positional relationships indicated by the terms "front", "rear", "left", "right", etc. described in the present invention are based on the directions and positional relationships shown in the accompanying drawings and are only for the convenience and simplification of description. They do not indicate or imply a specific orientation that the device or original referred to must have, nor can they be understood as limitations on the present invention.

[0042] Example 1 - Solid-solid heat exchange device startup protection device

[0043] like Figure 2 As shown, the solid-solid heat exchange device startup protection device includes a protection device heating pipe 3a, a superheated steam introduction pipe 3b, a mixing header 3c, an evaporation heating surface pipe outlet 3e and an evaporation heating surface pipe inlet 3f;

[0044] The protection device heating pipe 3a is arranged in the mixing header 3c, one end of the protection device heating pipe 3a is connected to the superheated steam introduction pipe 3b outside the mixing header 3c, and a plurality of small holes for discharging steam are evenly distributed on the protection device heating pipe 3a.

[0045] It is understandable that, as a reasonable extension, the small holes do not have to be arranged evenly and / or densely. The purpose of arranging the small holes evenly and densely is to heat the water in the mixing header 3c as efficiently as possible, so that it can generate more steam as quickly as possible.

[0046] The mixing header 3c is provided with an evaporation heating surface tube outlet 3e and an evaporation heating surface tube inlet 3f. The evaporation heating surface tube outlet 3e is provided above the mixing header 3c, and the evaporation heating surface tube inlet 3f is provided below the mixing header 3c.

[0047] In this embodiment, the evaporation heating surface pipe outlet 3e is used to connect to the inlet of the primary evaporator 1. The evaporation heating surface pipe inlet 3f is used to connect to the outlet of the secondary evaporator 4. In Embodiment 2, the heat exchange device using this will be described in detail.

[0048] After the heat exchange device is provided with the solid-solid heat exchange device startup protection device, the heat exchange device and the superheater serving as the evaporator can be well protected when the waste heat recovery boiler is started.

[0049] The solid-solid heat exchange device startup protection device is implemented as follows: a stream of steam is drawn from the side and enters the solid-solid heat exchange device startup protection device to heat the existing evaporator water to generate steam, thereby accelerating the establishment of water circulation. In this way, the evaporator and superheater will be well protected in the initial startup stage.

[0050] Specific working principle: At the initial start-up, high-temperature steam is introduced from the side and enters the mixing header 3c through the superheated steam introduction pipe 3b and the protection device heating pipe 3a. After the high-temperature steam enters the protection device heating pipe 3a, it is sprayed into the mixing header through the small hole, mixed with the water in the mixing header, and releases heat to heat the water in the mixing header to generate steam.

[0051] Because the solid-solid heat exchange device startup protection device will be set on the circulation loop of the heat exchange device as the primary evaporator 1 and the secondary evaporator 4 in actual application, the steam enters the primary evaporator 1 from the evaporation heating surface pipe outlet 3e, and forms a self-heating cycle due to the density difference between water and steam. At the same time, the steam enters the steam drum 5 for separation and then enters the superheater 3, thus forming a complete cycle. After that, the high-temperature material enters the waste heat recovery boiler. Then, after the high-temperature material contacts the heat exchange device and can continue the water circulation of the heat exchange device through the high-temperature material, the high-temperature steam is stopped.

[0052] Since a complete water cycle has been established at the beginning of the waste heat recovery boiler startup, all heating surfaces can be well cooled, and after adding high-temperature materials, all heating surfaces can operate normally, thus playing a good protective role.

[0053] Similarly, take a certain type of solid-solid heat exchange high-temperature waste heat recovery boiler described in the background technology as an example. Due to the establishment of the cycle, the evaporator's evaporation heating surface will be well cooled due to the flow of the medium in the tube, and the heat load of the evaporator's evaporation heating surface will also be greatly reduced, about 3*10^5W / m2, which will not cause the generation of film boiling, thereby well protecting the evaporator's evaporation heating surface tube; for the superheater 2 heating surface, even if there is a large heat flux density outside the tube, due to the flow of steam in the superheater tube, the heating surface of the tube is well cooled, and its metal wall temperature is greatly reduced to below 400°C. In this way, we can use ordinary carbon steel pipes to meet the use requirements, and the material and cost are greatly reduced.

[0054] We can use natural circulation to meet the requirements of high-temperature solid particle solid-solid heat exchange waste heat recovery device. In this way, we can save the high-temperature circulation pump. Not only can we reduce investment and energy consumption, but also reduce mechanical failure points.

[0055] Example 2 - Heat exchange device

[0056] The present invention also provides a heat exchange device, including a primary evaporator 1 and a secondary evaporator 4, and adopts the solid-solid heat exchange device startup protection device as described in Example 1, the inlet of the primary evaporator 1 is connected to the evaporation heating surface tube outlet 3e of the solid-solid heat exchange device startup protection device, and the outlet of the secondary evaporator 4 is connected to the evaporation heating surface tube inlet 3f of the solid-solid heat exchange device startup protection device.

[0057] like Figure 3 As shown, an example of a heat exchange device using a solid-solid heat exchange device to start the protection device is described in detail.

[0058] In this example, the mixing manifold 3c of the solid-solid heat exchange device startup protection device replaces the first-stage evaporator outlet manifold 1b of the first-stage evaporator 1 and the second-stage evaporator outlet manifold 4a of the second-stage evaporator 4, and each heating tube inlet of the first-stage evaporator 1 is connected to the evaporation heating surface tube outlet 3e; each heating tube outlet of the second-stage evaporator 4 is connected to the evaporation heating surface tube inlet 3f.

[0059] During the circulation, the water in the drum 5 first enters the secondary evaporator 4, and then enters the mixing header 3c after passing through the solid-solid heat exchange device and the start-up protection device.

[0060] It is reasonable to speculate that as a solid-solid heat exchange device startup protection device, more applications are: the solid-solid heat exchange device startup protection device can be applied separately to a certain stage of the evaporator, instead of connecting two stages of evaporators at the same time, but the two stages of evaporators are connected in series.

[0061] The working principle and beneficial effects of the heat exchange device, including the working principle and beneficial effects of the solid-solid heat exchange device startup protection device, have been explained in Example 1 and will not be repeated here.

[0062] In order to better understand the application of the solid-solid heat exchange device startup protection device and the heat exchange device, the present invention will also explain a cooling and waste heat recovery boiler for sintered ore and pelletized ore.

[0063] like Figure 4 As shown, the cooling and waste heat recovery boiler for sintered ore and pelletized ore is a solid-solid heat exchange high-temperature waste heat recovery boiler. The cooling and waste heat recovery boiler for sintered ore and pelletized ore adopts the heat exchange device described in Example 2 as the primary evaporator 1 and the secondary evaporator 4.

[0064] A superheater 2 is provided between the primary evaporator 1 and the secondary evaporator 4, and an economizer is provided below the secondary evaporator 4. The inlet of the superheater 2 is connected to the outlet at the top of the drum 5, and the inlet of the superheater 2 is connected to the steam pipe network. The inlet of the economizer is connected to the bottom of the drum 5, and the outlet of the economizer is connected to the upper part of the drum 5.

[0065] The present invention also provides a method for cooling and recovering waste heat of sintered ore and pelletized ore, using the cooling and waste heat boiler of sintered ore and pelletized ore, and the specific steps are as follows:

[0066] Step 1: At the initial start-up, high-temperature steam is introduced from the side and enters the mixing header 3c through the superheated steam introduction pipe 3b and the protection device heating pipe 3a. After the high-temperature steam enters the protection device heating pipe 3a, it is sprayed into the mixing header through the small hole, mixed with the water in the mixing header, and releases heat to heat the water in the mixing header to generate steam;

[0067] Step 2: Steam enters the primary evaporator 1 from the evaporation heating surface pipe outlet 3e, and forms an autothermal cycle due to the density difference between water and steam. At the same time, after the steam enters the steam drum 5 for separation, it enters the superheater 3, thus forming a complete cycle. After that, the high-temperature material enters the waste heat recovery boiler;

[0068] Step 3: After the high-temperature material contacts the heat exchange device and the water circulation of the heat exchange device can continue through the high-temperature material, stop introducing the high-temperature steam;

[0069] Step 4: After the high-temperature material passes through the heat exchange device and the superheater, it continues to be discharged downward through the economizer and the feeding device, completing the cooling of the sintered ore and the pelletized ore and the waste heat recovery.

[0070] The working principle and beneficial effects of the waste heat recovery boiler, including the working principle and beneficial effects of the solid-solid heat exchange device startup protection device therein, have been explained in Example 1 and will not be repeated again.

[0071] The specification and drawings of the present invention are considered to be illustrative rather than restrictive. On the basis of the present invention, those skilled in the art can make some substitutions and modifications to some of the technical features in accordance with the disclosed technical content without creative labor, all of which are within the protection scope of the present invention.

Claims

1. A solid-solid heat exchange device startup protection device, characterized in that: It comprises a protective device heating pipe (3a), a superheated steam introduction pipe (3b), a mixing header (3c), an evaporation heating surface pipe outlet (3e) and an evaporation heating surface pipe inlet (3f); The protection device heating pipe (3a) is arranged in the mixing header (3c), one end of the protection device heating pipe (3a) is connected to the superheated steam introduction pipe (3b) outside the mixing header (3c), and at least one small hole for discharging steam is arranged on the protection device heating pipe (3a); the mixing header (3c) is provided with an evaporation heating surface pipe outlet (3e) and an evaporation heating surface pipe inlet (3f), the evaporation heating surface pipe outlet (3e) is arranged above the mixing header (3c), and the evaporation heating surface pipe inlet (3f) is arranged below the mixing header (3c); there are a plurality of small holes, which are evenly and densely distributed on the protection device heating pipe (3a).

2. A method for using a startup protection device for a solid-solid heat exchange device, characterized in that: According to the solid-solid heat exchange device startup protection device as claimed in claim 1, before the heat exchange device using the solid-solid heat exchange device startup protection device is started, high-temperature steam is introduced from the side and enters the mixing header (3c) through the superheated steam introduction pipe (3b) and the protection device heating pipe (3a); after the high-temperature steam enters the protection device heating pipe (3a), it is sprayed into the mixing header through the small hole, mixed with the water in the mixing header, and releases heat to heat the water in the mixing header to generate steam, and the heat exchange device water circulation is established by the steam; then, after the high-temperature material contacts the heat exchange device and can continue the water circulation of the heat exchange device through the high-temperature material, the introduction of high-temperature steam is stopped.

3. A heat exchange device, characterized in that: It comprises the solid-solid heat exchange device startup protection device as claimed in claim 1; the evaporating heating surface tube outlet (3e) is connected to the inlet of the heat exchange device.

4. A heat exchange device, characterized in that: The invention comprises the solid-solid heat exchange device startup protection device as claimed in claim 1, a primary evaporator (1) and a secondary evaporator (4); the inlet of the primary evaporator (1) is connected to the evaporation heating surface tube outlet (3e) of the solid-solid heat exchange device startup protection device, and the outlet of the secondary evaporator (4) is connected to the evaporation heating surface tube inlet (3f) of the solid-solid heat exchange device startup protection device.

5. A heat exchange device, characterized in that: The invention comprises the solid-solid heat exchange device startup protection device as claimed in claim 1, a primary evaporator (1) and a secondary evaporator (4); the mixing header (3c) of the solid-solid heat exchange device startup protection device replaces the primary evaporator outlet header (1b) of the primary evaporator (1) and the secondary evaporator outlet header (4a) of the secondary evaporator (4); the heating tube inlets of the primary evaporator (1) are connected to the evaporation heating surface tube outlet (3e); the heating tube outlets of the secondary evaporator (4) are connected to the evaporation heating surface tube inlet (3f).

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