Process gas preheating system with flue gas denitration and heat recovery functions

Abstract

The utility model relates to a process gas preheating system with flue gas denitration and heat recovery functions. The process gas preheating system comprises a regeneration preheating device, a process gas preheater, a denitration reactor, a combustion-supporting gas preheater and a tail gas emission device which are sequentially connected along the flow direction of flue gas, part of flue gas exhausted by the process gas preheater is recycled to the regeneration preheating device through a flue gas circulating device; the combustion-supporting gas preheater is connected with the regeneration preheating device, and the combustion-supporting gas preheater is used for providing combustion-supporting gas for the regeneration preheating device. According to the utility model, heat recovery and cyclic utilization of flue gas are realized while process gas is preheated, and the device has the characteristics of energy conservation and environmental protection.

Description

Technical Field

[0001] The utility model relates to the technical field of process gas preheating, in particular to a process gas preheating system including flue gas denitration and heat recovery. Background Art

[0002] The process gas preheating system is a system used to heat the gas in the industrial process. It heats the gas entering the process to the required temperature in advance to improve process efficiency and energy utilization. The process gas preheating system usually consists of a heater, a control system, pipelines and valves, heat exchange equipment, and a safety system. By preheating the process gas, the system can reduce energy consumption, save production costs, and improve the efficiency of the process. At present, process gas preheating technology has been widely used in various industrial fields, such as chemical industry, manufacturing industry, and energy production.

[0003] After preheating the process gas, if the high-temperature heat of the recovered heat medium is not recovered or recovered incompletely, it will increase energy consumption and be detrimental to sustainable development. At the same time, the heat medium also needs to be post-treated such as denitrification. Direct discharge into the atmosphere will cause serious environmental pollution.

[0004] For example, CN 102778035A discloses an explosive gas heating process and equipment, which is mainly composed of a heat storage heating furnace, a mixing chamber, pipes, valves, fans, heat exchangers, etc. The system is equipped with 2 to 4 heating furnaces, each of which works alternately for heat storage and heating. During the heat storage period, the coal gas is burned to heat the heat storage body in the heating furnace. During the heating period, a part of the explosive gas flows through the heat storage body and is heated by the heat storage body. The hot explosive gas is discharged from the furnace and enters the mixing chamber, and is mixed with another part of the explosive gas in the mixing chamber to mix out hot explosive gas that meets the requirements of the next step. However, the equipment only discloses the heating of the explosive gas, and does not utilize the heat of heat exchange, resulting in high energy consumption.

[0005] CN 205208599U discloses a flue gas waste heat recovery system of an oxygen-enriched combustion boiler and an oxygen-enriched combustion boiler, wherein the flue gas waste heat recovery system comprises a primary flue gas circulation system, wherein the primary flue gas circulation system comprises a heat recovery device, a flue gas condenser and a primary flue gas reheater connected in sequence through a flue, wherein the high-temperature flue gas discharged from the boiler enters the heat recovery device and undergoes heat exchange, wherein the flue gas after heat exchange is condensed through a flue gas condenser, wherein at least a portion of the condensed flue gas is heated through a primary flue gas reheater, and the heated flue gas is returned to the boiler; wherein the heat recovery device and the primary flue gas reheater are connected through a first circulation pipeline to form a first heat circulation system, wherein a heat exchange medium is introduced into the first circulation pipeline. Although the flue gas waste heat is recovered in the system, the heat exchange temperature difference can reach up to 100°C or more, thereby increasing the entropy increment of the heat energy transfer process and resulting in an increase in the loss of high-temperature flue gas.

[0006] Therefore, in view of the shortcomings of the prior art, there is an urgent need to provide a process gas preheating system that can recover the heat of the flue gas after preheating the process gas and discharge it after denitrification. Utility Model Content

[0007] The utility model aims to provide a process gas preheating system including flue gas denitrification and heat recovery, which realizes heat recovery and recycling of flue gas while preheating the process gas, and has the characteristics of energy saving and environmental protection.

[0008] In order to achieve the purpose of this utility model, the utility model adopts the following technical solutions:

[0009] The utility model provides a process gas preheating system containing flue gas denitration and heat recovery, the process gas preheating system comprising a regeneration preheating device, a process gas preheater, a denitration reactor, a combustion-supporting gas preheater and an exhaust gas emission device which are sequentially connected along the flow direction of the flue gas; part of the flue gas discharged by the process gas preheater is recycled to the regeneration preheating device through a flue gas circulation device; the combustion-supporting gas preheater is connected to the regeneration preheating device, and the combustion-supporting gas preheater is used to provide combustion-supporting gas for the regeneration preheating device.

[0010] The utility model provides a process gas preheating system with flue gas denitrification and heat recovery, which adopts a regenerative preheating device and a process gas preheater to form a process gas preheating system. By recycling part of the flue gas discharged from the process gas preheater back to the regenerative preheating device, the heat utilization rate can be improved and the NO in the flue gas can be reduced. x The remaining flue gas is then sent to the denitration reactor, and the heat of the denitrated flue gas is utilized in the combustion-supporting gas preheater. The combustion-supporting gas is heated and sent to the regeneration preheating device to be burned together with the fuel gas, so that the process gas that needs to be preheated can be heated in the process gas preheater. The process gas preheating system can realize the heat recovery and recycling of the flue gas while preheating the process gas, and has the characteristics of energy saving and environmental protection.

[0011] Preferably, the regeneration preheating device is provided with a fuel gas inlet.

[0012] Preferably, the regeneration preheating device comprises a horizontal regeneration preheating furnace.

[0013] The horizontal regeneration preheating furnace mainly includes a forced ventilation burner, a fuel gas feeding system, an ignition system and an ultraviolet fire detection.

[0014] Preferably, the inner cavity of the process gas preheater is provided with a shell layer and a tube layer, the shell layer is used for circulating the flue gas, and the tube layer is used for circulating the process gas.

[0015] Preferably, the temperature of the circulating flue gas is ≤800°C, for example, it may be 800°C, 780°C, 750°C, 730°C or 700°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0016] Preferably, the temperature of the circulating process gas is ≤542°C, for example, it can be 542°C, 540°C, 535°C, 530°C or 520°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0017] Preferably, the shell is provided with a spoiler.

[0018] The provision of the spoiler can improve the heat exchange efficiency of the process gas preheater.

[0019] Preferably, the shell layer and the tube layer are each independently provided with a thermal insulation layer.

[0020] The shell layer and the pipe layer are both made of 304H with an outer insulation layer.

[0021] It should be noted that the utility model does not specifically limit the thickness structural characteristics of the insulation layer. The function of the insulation layer in the utility model is to provide insulation for the shell layer and the tube layer. Therefore, it can be understood that other insulation layers that can achieve such functions can be used in the utility model, and technical personnel in this field can adaptively adjust the thickness of the insulation layer according to the usage scenario and application conditions.

[0022] Preferably, the process gas preheater is provided with a process gas outlet and a flue gas outlet.

[0023] Preferably, the top end and the bottom end of the process gas preheater are independently provided with a preheated air inlet and a preheated air outlet respectively.

[0024] Preferably, the flue gas circulation device comprises a flue gas circulation fan.

[0025] Preferably, the combustion-aiding gas preheater is connected to a combustion-aiding gas blower.

[0026] Preferably, the combustion-supporting gas comprises air.

[0027] Preferably, the exhaust gas emission device comprises a chimney.

[0028] Exemplarily, the operation process of the process gas preheating system provided by the utility model is as follows:

[0029] The fuel gas and the combustion-supporting gas from the self-fuel gas preheater are burned in the regeneration preheating device to generate high-temperature flue gas. The high-temperature flue gas enters the process gas preheater and exchanges heat with the process gas. The process gas is discharged from the process gas outlet after the temperature is increased. Part of the flue gas after heat exchange is recycled to the regeneration preheating device through the flue gas circulation device, and part of it enters the denitrification reactor for denitrification treatment. It is then sent to the combustion-supporting gas preheater for heat exchange with the combustion-supporting gas from the self-fuel gas fan. The flue gas after heat exchange enters the exhaust gas emission device and is discharged into the atmosphere. After the combustion-supporting gas is heated, it is sent to the regeneration preheating device to form a cycle.

[0030] Compared with the prior art, the utility model has the following beneficial effects:

[0031] The utility model provides a process gas preheating system with flue gas denitrification and heat recovery, which adopts a regenerative preheating device and a process gas preheater to form a process gas preheating system. By recycling part of the flue gas discharged from the process gas preheater back to the regenerative preheating device, the heat utilization rate can be improved and the NO in the flue gas can be reduced. x The remaining flue gas is then sent to the denitration reactor, and the heat of the denitrated flue gas is utilized in the combustion-supporting gas preheater. The combustion-supporting gas is heated and sent to the regeneration preheating device to be burned together with the fuel gas, so that the process gas that needs to be preheated can be heated in the process gas preheater. The process gas preheating system can realize the heat recovery and recycling of the flue gas while preheating the process gas, and has the characteristics of energy saving and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the structure of a process gas preheating system including flue gas denitration and heat recovery provided in Example 1 of the utility model;

[0033] Among them: 1. Horizontal regeneration preheating furnace; 2. Process gas preheater; 3. Denitrification reactor; 4. Auxiliary gas preheater; 5. Chimney; 6. Flue gas circulation fan; 7. Auxiliary gas fan. DETAILED DESCRIPTION

[0034] The technical solution of the present invention is further described below by specific implementation methods. Those skilled in the art should understand that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0035] Example 1

[0036] This embodiment provides a process gas preheating system including flue gas denitrification and heat recovery, such as Figure 1As shown, the process gas preheating system comprises a horizontal regenerative preheating furnace 1, a process gas preheater 2, a denitration reactor 3, a combustion-supporting gas preheater 4 and a chimney 5 which are sequentially connected along the flue gas flow direction; part of the flue gas discharged from the process gas preheater 2 is recycled to the horizontal regenerative preheating furnace 1 through a flue gas circulation fan 6; the combustion-supporting gas preheater 4 is connected to the horizontal regenerative preheating furnace 1, and the combustion-supporting gas preheater 4 is used to provide combustion-supporting gas for the horizontal regenerative preheating furnace 1, and the combustion-supporting gas preheater 4 is connected to a combustion-supporting gas fan 7;

[0037] The horizontal regeneration preheating furnace 1 is provided with a fuel gas inlet;

[0038] The inner cavity of the process gas preheater 2 is provided with a shell layer and a tube layer, the shell layer is used for circulating flue gas, and the tube layer is used for circulating process gas; the shell layer is provided with a spoiler; the shell layer and the tube layer are independently provided with insulation layers; the process gas preheater 2 is provided with a process gas outlet and a flue gas outlet; the top and bottom ends of the process gas preheater 2 are independently provided with a preheated air inlet and a preheated air outlet.

[0039] When applying the process gas preheating system:

[0040] The fuel gas and the air from the auxiliary gas preheater 4 are burned in the horizontal regenerative preheating furnace 1 to generate high-temperature flue gas, which enters the process gas preheater 2 to exchange heat with the process gas. The process gas is heated and discharged from the process gas outlet. After the flue gas after heat exchange is discharged from the flue gas outlet, part of it is recycled to the horizontal regenerative preheating furnace 1 through the flue gas circulation fan 6, and part of it enters the denitrification reactor 3 for denitrification treatment, and then is sent to the auxiliary gas preheater 4 to exchange heat with the air from the auxiliary gas fan 7. The flue gas after heat exchange enters the chimney 5 and is discharged into the atmosphere. After the air is heated, it is sent to the horizontal regenerative preheating furnace 1 to form a cycle.

[0041] The process gas preheating system can realize heat recovery and recycling of flue gas while preheating the process gas, and can finally be discharged into the atmosphere after denitrification, thus having the characteristics of energy saving and environmental protection.

[0042] Example 2

[0043] This embodiment provides a process gas preheating system including flue gas denitrification and heat recovery. The difference from Embodiment 1 is that the shell layer is not provided with a spoiler, and the rest is the same as Embodiment 1.

[0044] Since the shell is not provided with a spoiler, the heat exchange efficiency in the process gas preheater is reduced. The process gas preheating system can achieve preheating of the process gas, but it takes a long time.

[0045] Comparative Example 1

[0046] This comparative example provides a process gas preheating system with flue gas denitration and heat recovery, the process gas preheating system comprising a horizontal regenerative preheating furnace 1, a process gas preheater 2, a denitration reactor 3, a combustion-supporting gas preheater 4 and a chimney 5 which are sequentially connected along the flue gas flow direction; the combustion-supporting gas preheater 4 is connected to the horizontal regenerative preheating furnace 1, the combustion-supporting gas preheater 4 is used to provide combustion-supporting gas for the horizontal regenerative preheating furnace 1, and the combustion-supporting gas preheater 4 is connected to a combustion-supporting gas blower 7;

[0047] The horizontal regeneration preheating furnace 1 is provided with a fuel gas inlet;

[0048] The inner cavity of the process gas preheater 2 is provided with a shell layer and a tube layer, the shell layer is used for circulating flue gas, and the tube layer is used for circulating process gas; the shell layer is provided with a spoiler; the shell layer and the tube layer are independently provided with insulation layers; the process gas preheater 2 is provided with a process gas outlet and a flue gas outlet; the top and bottom ends of the process gas preheater 2 are independently provided with a preheated air inlet and a preheated air outlet.

[0049] When applying the process gas preheating system:

[0050] The fuel gas and the air from the auxiliary gas preheater 4 are burned in the horizontal regenerative preheating furnace 1 to generate high-temperature flue gas. The high-temperature flue gas enters the process gas preheater 2 to exchange heat with the process gas. The process gas is heated and discharged from the process gas outlet. After the flue gas after heat exchange is discharged from the flue gas outlet, it all enters the denitration reactor 3 for denitration treatment, and then is sent to the auxiliary gas preheater 4 to exchange heat with the air from the auxiliary gas fan 7. The flue gas after heat exchange enters the chimney 5 and is discharged into the atmosphere. After the air is heated, it is sent to the horizontal regenerative preheating furnace 1 to form a cycle.

[0051] The process gas preheating system can realize preheating of the process gas and also realize heat recovery of the flue gas, but cannot recycle the flue gas, thereby reducing the heat utilization rate.

[0052] Comparative Example 2

[0053] This comparative example provides a process gas preheating system including flue gas denitrification and heat recovery, which differs from Example 1 in that no combustion-supporting gas preheater 4 is provided, the denitrification reactor 3 is connected to the chimney 5, and the rest is the same as Example 1.

[0054] The process gas preheating system can realize preheating of the process gas, but cannot realize heat recovery of the flue gas, which significantly increases the energy consumption of the system.

[0055] In summary, the process gas preheating system with flue gas denitration and heat recovery provided by the utility model adopts a regenerative preheating device and a process gas preheater to form a process gas preheating system. By recycling part of the flue gas discharged from the process gas preheater back to the regenerative preheating device, the heat utilization rate can be improved and the NOx content in the flue gas can be reduced; then the remaining flue gas discharged is sent to the denitration reactor, and the heat of the obtained denitrified flue gas is utilized in the combustion-supporting gas preheater. The combustion-supporting gas is heated and sent to the regenerative preheating device to be burned together with the fuel gas, so that the process gas that needs to be preheated can be heated in the process gas preheater. The process gas preheating system realizes the preheating of the process gas while also realizing the heat recovery and recycling of the flue gas, and has the characteristics of energy saving and environmental protection.

[0056] The above description is only a specific implementation method of the present utility model, but the protection scope of the present utility model is not limited thereto. Technicians in the relevant technical field should understand that any changes or substitutions that can be easily thought of by technicians in the relevant technical field within the technical scope disclosed in the present utility model fall within the protection scope and disclosure scope of the present utility model.

Claims

1. A process gas preheating system with flue gas denitrification and heat recovery, characterized in that: The process gas preheating system comprises a regeneration preheating device, a process gas preheater, a denitration reactor, a combustion-supporting gas preheater and an exhaust gas emission device which are sequentially connected along the flow direction of the flue gas; part of the flue gas discharged from the process gas preheater is recycled to the regeneration preheating device through a flue gas circulation device; the combustion-supporting gas preheater is connected to the regeneration preheating device, and the combustion-supporting gas preheater is used to provide combustion-supporting gas for the regeneration preheating device.

2. The process gas preheating system according to claim 1, characterized in that: The regeneration preheating device is provided with a fuel gas inlet.

3. The process gas preheating system according to claim 1, characterized in that: The regeneration preheating device comprises a horizontal regeneration preheating furnace.

4. The process gas preheating system according to claim 1, characterized in that: The inner cavity of the process gas preheater is provided with a shell layer and a tube layer, the shell layer is used for circulating flue gas, and the tube layer is used for circulating process gas.

5. The process gas preheating system according to claim 4, characterized in that: The shell layer is provided with a spoiler.

6. The process gas preheating system according to claim 4, characterized in that: The shell layer and the tube layer are independently provided with insulation layers.

7. The process gas preheating system according to claim 4, characterized in that: The process gas preheater is provided with a process gas outlet and a flue gas outlet.

8. The process gas preheating system according to claim 1, characterized in that: The top end and the bottom end of the process gas preheater are independently provided with a preheated air inlet and a preheated air outlet.

9. The process gas preheating system according to claim 1, characterized in that: The flue gas circulation device comprises a flue gas circulation fan.

10. The process gas preheating system according to claim 1, characterized in that: The combustion-aiding gas preheater is connected to a combustion-aiding gas blower.

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