Waste heat recovery safety system based on metal fiber surface combustion technology CEB

Abstract

The invention discloses a CEB waste heat recovery safety system and method based on the metal fiber surface combustion technology, the system comprises a CEB direct combustion device, a combined air inducing device, a waste heat recovery unit and a control unit, the combined air inducing device is arranged at the rear end of a smoke outlet of the CEB direct combustion device, and an air inducing channel and an emergency discharge channel are arranged in the combined air inducing device in parallel; the control unit monitors system pressure parameters in real time, controls the air inducing channel to be opened under the normal working condition, and introduces high-temperature flue gas into the waste heat recovery unit for heat energy recovery. When it is monitored that the pressure exceeds a safety threshold value, the combined air inducing device is immediately controlled to be switched to an emergency relief channel, smoke is directly exhausted into the atmosphere, and rapid pressure relief is achieved. By means of a double-channel switching mechanism of the combined air inducing device, the adaptability problem of CEB direct combustion equipment and a waste heat recovery system under the fluctuating load is effectively solved, and the safety of the CEB direct combustion equipment and the waste heat recovery system is improved. The device has efficient waste heat recovery and intrinsic safety protection capabilities, and is suitable for storage and transportation tank areas, loading platforms and other scenes where waste gas loads fluctuate severely.

Description

Technical Field

[0001] This invention relates to the field of industrial waste gas treatment and waste heat utilization technology, specifically a CEB waste heat recovery safety system based on metal fiber surface combustion technology. Background Technology

[0002] In industries such as petroleum, chemical, and storage and transportation, a large amount of unstable waste gas is generated in storage and transportation tank areas and loading processes. This type of waste gas has a complex composition and large concentration fluctuations, containing a large amount of volatile organic compounds. Direct discharge will cause serious environmental pollution. In particular, the waste gas from the loading and unloading of tank cars on railways and highways has a strong instantaneous emission and a pulse-like characteristic with alternating peaks and valleys in flow and concentration, which places extremely high demands on the instantaneous response and stable operation capabilities of the treatment equipment.

[0003] Currently, the CEB (Clean Emission Burner) direct combustion equipment, which uses metal fiber surface combustion technology, is one of the mainstream devices for treating this type of waste gas. This technology utilizes a metal fiber burner made of alloys such as FeCrAl, whose surface forms countless micron-level channels, allowing the premixed gas of waste gas and air to undergo flameless combustion on the fiber surface. It features uniform combustion, short flame, and low pollutant generation. Through premixed combustion, it can achieve a VOCs removal rate of ≥99.99% and ultra-low emissions of pollutants such as nitrogen oxides and carbon monoxide, meeting stringent environmental protection standards.

[0004] However, CEB direct-fired equipment typically operates at temperatures between 1000℃ and 1200℃, and the resulting flue gas contains a large amount of recoverable heat energy. From the perspective of energy cascade utilization and energy conservation and emission reduction, recovering this waste heat has significant economic and environmental benefits. However, in existing technologies, if a conventional waste heat recovery system is directly installed at the back end of the CEB, the following serious challenges are likely to be encountered:

[0005] (1) The incineration load of the storage and transportation tank area and the loading exhaust gas changes at any time, which causes the flue gas flow and temperature of the CEB direct combustion equipment to flue frequently. Conventional waste heat recovery systems are usually designed for steady-state or slowly changing conditions. Their induced draft device has a slow dynamic response speed and cannot quickly adapt to the sudden load change at the front end of the CEB. This can easily cause the pressure of the CEB premixing chamber and combustion chamber to be unstable, which can damage the flow field and flame stability of the premixed gas.

[0006] (2) Pressure fluctuations, especially when the pressure in the premixing chamber is higher than the supply pressure of the mixed gas, can easily cause backfire and even lead to flash explosion accidents, seriously threatening the safety of equipment and personnel.

[0007] Therefore, pressure instability is a key technical bottleneck that limits the safe coupling of CEB equipment and downstream waste heat recovery system;

[0008] (3) The high temperature resistance of the inlet flue, heat exchange elements and matching valves of conventional waste heat recovery systems is insufficient. They are usually designed for flue gas below 800℃ and cannot withstand the high temperature flue gas above 1200℃ discharged from CEB for a long time. This can easily lead to problems such as high temperature oxidation of materials, creep deformation, and embrittlement failure of sealing materials. The long-term reliability is poor and there is a risk of high temperature flue gas leakage.

[0009] To address the aforementioned safety and compatibility challenges, the industry urgently needs an innovative core device that can ensure the stable introduction of high-temperature flue gas into the waste heat recovery system and respond instantly to sudden changes in operating conditions, thereby ensuring the safe operation of the CEB itself.

[0010] In summary, developing a CEB waste heat recovery safety system that can adapt to load fluctuations and has both high-temperature tolerance and rapid emergency protection functions has become an urgent technical problem to be solved. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of the prior art and provide a CEB waste heat recovery safety system based on metal fiber surface combustion technology. This system aims to solve the problems of poor compatibility, unstable pressure and high safety risks between CEB direct combustion devices and waste heat recovery systems when dealing with fluctuating waste gas.

[0012] To achieve the above objectives, the present invention adopts the following technical solution:

[0013] A CEB waste heat recovery safety system based on metal fiber surface combustion technology mainly includes a CEB direct combustion device, a waste heat recovery unit, a combined induced draft device, and a control unit.

[0014] The CEB direct combustion device is used to efficiently treat volatile organic waste gas using a premixed combustion method.

[0015] The waste heat recovery unit includes a steam generator, a steam drum, a feedwater preheater, and an induced draft fan connected in sequence through a flue. The outlet of the induced draft fan is connected to a chimney to recover the heat energy in the high-temperature flue gas and convert it into steam or hot water.

[0016] The combined induced draft device is the core safety component of this system. It is installed in the flue between the flue gas outlet of the CEB direct combustion unit and the steam generator of the waste heat recovery unit. The device has parallel induced draft channels and emergency relief channels inside. The induced draft channels are connected to the flue leading to the steam generator for waste heat recovery under normal operating conditions. The emergency relief channels have an outlet that leads directly to the atmosphere for rapid pressure relief in emergency conditions.

[0017] The control unit is connected to the CEB direct combustion device, the combined induced draft device and the waste heat recovery unit by signal, and is used to monitor the operating parameters of the system in real time, and control the combined induced draft device to switch between the induced draft channel and the emergency relief channel based on the monitored parameters, so as to balance heat recovery and system safety.

[0018] As a preferred embodiment of the present invention, the emergency relief channel of the combined induced draft device is equipped with a rapid opening and closing mechanism, and the control unit is configured to: when the system pressure is detected to exceed a first preset threshold, immediately control the mechanism to open the emergency relief channel to achieve millisecond-level rapid pressure relief.

[0019] Furthermore, the exhaust duct is equipped with a damper adjustment mechanism. The control unit can dynamically adjust the opening of the damper according to the real-time operating load of the CEB direct combustion device to stabilize the flue gas flow and buffer pressure fluctuations.

[0020] Preferably, the combined exhaust fan is made of a high-temperature resistant alloy to ensure its long-term stable operation in the high-temperature flue gas above 1200°C discharged from the CEB direct combustion device.

[0021] An improvement of the present invention is that the control unit is also configured with a multi-level safety protection strategy. When the system pressure is detected to exceed a higher second preset threshold, the control unit will trigger the emergency shutdown procedure of the CEB direct combustion device, thereby providing a deeper level of safety protection.

[0022] The system of the present invention may further include an oil and gas pretreatment unit, the outlet of which is connected to the inlet of the CEB direct combustion device, for pretreatment of high-concentration exhaust gas to reduce the load on the main combustion device.

[0023] Accordingly, the present invention also discloses a waste heat recovery safety control method based on the above system, the method mainly comprising:

[0024] S1. Real-time monitoring of pressure parameters in key components of the CEB direct-fired unit;

[0025] S2. Under normal operating conditions, control the combined induced draft device to open the induced draft channel for waste heat recovery;

[0026] S3. When the pressure parameter is detected to exceed the preset safety threshold, the combined induced draft device is controlled to open the emergency relief channel, so that the flue gas is directly discharged into the atmosphere, thereby ensuring system safety.

[0027] The beneficial effects of this invention are as follows:

[0028] (1) By integrating a combined induced draft device with a fast opening and closing mechanism, instantaneous response and release are achieved when the pressure is abnormal, thus fundamentally eliminating the risk of backfire and flash explosion.

[0029] (2) By linking the control unit with the damper adjustment mechanism, the system can automatically adapt to the load fluctuation of the exhaust gas at the front end, maintain the internal pressure of the CEB direct combustion device, and solve the coupling problem with the waste heat recovery system.

[0030] (3) Under the premise of ensuring safety, high-quality flue gas waste heat is efficiently recovered, resulting in high overall energy utilization efficiency, while ensuring ultra-low emissions of pollutants.

[0031] (4) The core components are made of high-temperature resistant materials and designed to ensure the long-term service life and reliability of the system under harsh working conditions.

[0032] In summary, the CEB waste heat recovery safety system provided by this invention, by introducing a combined induced draft device with dual-channel switching function and its intelligent control strategy, effectively fills the gap in existing technologies that struggle to balance efficient waste heat recovery and inherent system safety when dealing with highly fluctuating waste gases. This solution significantly improves the stability, safety, and energy utilization efficiency of the coupled operation of the CEB direct combustion device and the waste heat recovery system, providing a practical new technology path for the field of industrial waste gas treatment. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the CEB waste heat recovery safety system based on metal fiber surface combustion technology as described in this invention.

[0034] Figure 2 This is the workflow diagram of this system;

[0035] In the diagram, 1. CEB direct-fired unit; 2. Combined induced draft unit; 3. Steam generator; 4. Steam drum; 5. Feedwater preheater; 6. Induced draft fan; 7. Chimney. Detailed Implementation

[0036] To enhance understanding of the present invention, the invention will be further described in detail below with reference to embodiments and accompanying drawings. These embodiments are only for explaining the invention and do not constitute a limitation on the scope of protection of the invention.

[0037] CEB direct combustion unit 1; combined induced draft unit 2; steam generator 3; steam drum 4; feedwater preheater 5; induced draft fan 6; chimney 7.

[0038] refer to Figure 1 The present invention provides a CEB waste heat recovery safety system based on metal fiber surface combustion technology, which mainly consists of a CEB direct combustion device 1, a combined induced draft device 2, a waste heat recovery unit and a control unit.

[0039] The waste heat recovery unit includes a steam generator 3, a steam drum 4, a feedwater preheater 5, an induced draft fan 6, and a chimney 7, which are connected in sequence through a flue.

[0040] The CEB direct combustion device 1 is the core of the waste gas treatment system. It adopts a premixed combustion method, and the core component is a metal fiber burner. The burner is preferably woven from iron-chromium-aluminum (FeCrAl) alloy fibers to form a three-dimensional mesh structure with a large number of micron-level channels. After the waste gas and air are fully mixed in the premixing chamber of the device, they are transported to the surface of the metal fiber burner for flameless combustion. The combustion temperature is stably maintained in the high temperature range of 1000℃~1200℃. At this temperature, VOCs in the waste gas are completely decomposed, achieving a removal rate of up to 99.99% or more, and ensuring that the emission concentrations of nitrogen oxides (NOx) and carbon monoxide (CO) are extremely low.

[0041] The combined induced draft device 2 is the core of safety and key innovation of this system. It is directly installed above the flue gas outlet of the CEB direct combustion device 1 and is made of high temperature resistant alloy (such as 310S stainless steel). It can withstand high temperature flue gas above 1200℃ for a long time. The device has two parallel channels: an induced draft channel and an emergency discharge channel.

[0042] The induced draft duct is connected to the inlet of the downstream steam generator 3 through the flue, and a damper adjustment mechanism is installed inside to precisely control the flow rate of flue gas leading to the waste heat recovery unit.

[0043] The emergency venting channel is set up independently, with its outlet directly connected to the atmosphere. It is equipped with a rapid opening and closing mechanism, which is required to have a full opening time of no more than 2 seconds to ensure instantaneous depressurization in emergency situations.

[0044] In addition, for ease of maintenance, the outside of the combined ventilation system 2 is usually equipped with a maintenance platform with a load-bearing capacity of not less than 500 kg / m² and a guardrail with a height of not less than 1.2 meters.

[0045] The waste heat recovery unit is responsible for recovering the heat energy from the high-temperature flue gas. The high-temperature flue gas from the combined induced draft device 2 first enters the steam generator 3, where it exchanges heat with the heat exchange tube bundle inside the generator. The deoxygenated water flowing inside the tube bundle is heated and vaporized, forming a steam-water mixture. The steam-water mixture enters the steam drum 4 through the riser pipe. The steam drum 4 is equipped with steam-water separation devices such as corrugated plates and steam equalization orifice plates, which can effectively separate water and steam, ensuring that the water content of the produced steam is not higher than 0.5%. The separated saturated steam can be supplied externally, while the steam drum... Water returns to the steam generator 3 through the downcomer, forming a natural circulation. The flue gas exiting the steam generator 3 has been cooled but still retains residual heat. It then enters the feedwater preheater 5 to preheat the deoxygenated water that will soon enter the steam drum 4, thereby further improving the overall thermal efficiency of the system. Finally, the fully cooled flue gas is discharged into the atmosphere by the induced draft fan 6 through the chimney 7. The induced draft fan 6 preferably adopts a variable frequency explosion-proof design, and its impeller is made of 304 stainless steel. It can automatically adjust the speed according to the system resistance to ensure the stability of the flue gas flow.

[0046] The control unit, as the core control system of the system, typically adopts a DCS (Distributed Control System) or a high-performance PLC (Programmable Logic Controller). It collects pressure and temperature data of the premixing chamber and combustion chamber of the CEB direct combustion unit 1 in real time through high-precision pressure and temperature sensors, as well as parameters at various points in the flue. Based on this real-time data, the control unit dynamically adjusts the opening degree of the damper adjustment mechanism in the combined induced draft device 2 and the rotation speed of the induced draft fan 6 in the waste heat recovery unit through a built-in PID control algorithm to maintain the stability of system pressure and flow.

[0047] The emergency protection unit is responsible for the system's safety interlock, and it is set with at least two levels of pressure protection thresholds:

[0048] (1) When the pressure in the premixing chamber or combustion chamber exceeds the first preset threshold, the control unit immediately triggers the emergency protection, instructs the combined induced draft device 2 to close the induced draft channel and fully open the emergency relief channel, so that the high temperature flue gas is directly discharged to the atmosphere, thereby achieving rapid pressure relief.

[0049] (2) If the pressure continues to rise for any reason and exceeds the second preset threshold, the control unit will start the emergency shutdown procedure, immediately close the exhaust gas inlet valve and burner of the CEB direct combustion device 1, keep the emergency relief channel open, and trigger the audible and visual alarm to notify the operator to intervene.

[0050] Optionally, the system front end can also integrate an oil and gas pretreatment unit, which may include devices such as condensers, absorption towers or adsorption tanks, to pretreat high-concentration waste gas, reduce its oil and gas concentration, thereby reducing the treatment load of CEB direct combustion unit 1 and recovering some valuable oil products.

[0051] Implementation example:

[0052] Taking a petrochemical storage and transportation tank area waste gas treatment and energy recovery project as an example, the tank area generates organic waste gas with drastic fluctuations in concentration and flow rate during the loading and unloading of oil products.

[0053] This project uses a system of the present invention with a rated heat capacity of 2MW for processing. In the system configuration, the first and second pressure preset thresholds of the control unit are set to 1.5kPa and 2.0kPa, respectively.

[0054] After the system is put into operation, under normal circumstances, the exhaust gas from the tank area is introduced into the CEB direct combustion unit 1 for stable combustion. The high-temperature flue gas enters the subsequent steam generator 3 and feedwater preheater 5 smoothly through the induced draft channel of the combined induced draft device 2, which is in the open state, and continuously produces 0.8MPa saturated steam for production use. The system pressure is stable at about 1.0kPa, and the waste heat recovery efficiency is maintained at more than 87%.

[0055] In a sudden emergency, multiple tank trucks simultaneously carried out rapid loading operations, causing a surge in the instantaneous influx of exhaust gas. The pressure inside the CEB direct combustion unit 1 rapidly climbed to 1.6 kPa, exceeding the first preset threshold. The control unit responded immediately, issuing a command within milliseconds to drive the combined induced draft fan 2 to quickly switch states within 1.5 seconds, closing the induced draft duct and fully opening the emergency venting channel. This allowed the suddenly increased high-temperature flue gas to be directly introduced into the atmosphere, thereby quickly suppressing the pressure rise and effectively avoiding the risk of backfire caused by pressure fluctuations and the impact on the downstream waste heat recovery equipment.

[0056] Once the system pressure returns to a safe range, the control unit automatically executes the status recovery procedure, closes the emergency relief channel and reopens the exhaust channel, and the system seamlessly switches back to normal waste heat recovery mode.

[0057] This application example fully demonstrates that the system of the present invention can reliably ensure equipment safety and achieve continuous and efficient energy recovery when dealing with extreme fluctuating loads.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A CEB waste heat recovery safety system based on metal fiber surface combustion technology, characterized in that, include: CEB direct combustion unit, waste heat recovery unit, combined induced draft unit and control unit; The CEB direct combustion device uses a premixed combustion method to treat waste gas. The waste heat recovery unit includes a steam generator, a steam drum, a feedwater preheater, and an induced draft fan connected in sequence through a flue, with the outlet of the induced draft fan connected to a chimney. The combined induced draft device is installed on the flue between the flue gas outlet of the CEB direct combustion device and the steam generator of the waste heat recovery unit. The combined induced draft device is equipped with parallel induced draft channels and emergency venting channels; the induced draft channels are connected to the flue leading to the steam generator; the emergency venting channels are equipped with an outlet that leads directly to the atmosphere. The control unit is connected to the CEB direct combustion unit, the combined induced draft unit and the waste heat recovery unit by signal. It monitors the system operating parameters and controls the combined induced draft unit to switch between the induced draft channel and the emergency relief channel based on the operating parameters.

2. The CEB waste heat recovery safety system according to claim 1, characterized in that, The emergency relief channel of the combined ventilation device is equipped with a quick-opening and closing mechanism. The control unit is configured to control the quick-opening and closing mechanism to open the emergency relief channel when the system pressure is detected to exceed a first preset threshold.

3. The CEB waste heat recovery safety system according to claim 1, characterized in that, The air intake duct is equipped with a damper adjustment mechanism. The control unit is signal-connected to the damper adjustment mechanism and adjusts the opening of the damper according to the operating load of the CEB direct combustion device.

4. The CEB waste heat recovery safety system according to claim 1, characterized in that, The combined exhaust fan is made of high-temperature resistant alloy.

5. The CEB waste heat recovery safety system according to claim 1, characterized in that, The CEB direct combustion device includes a metal fiber burner, which is made of woven iron-chromium-aluminum alloy fibers.

6. The CEB waste heat recovery safety system according to claim 1, characterized in that, The steam drum is equipped with a steam-water separation device.

7. The CEB waste heat recovery safety system according to claim 1, characterized in that, The control unit includes an industrial automation control system, such as a DCS or PLC; the control unit acquires the system operating parameters through pressure sensors and temperature sensors installed on the premixing chamber and combustion chamber of the CEB direct combustion device.

8. The CEB waste heat recovery safety system according to claim 2, characterized in that, The control unit is also configured to trigger the emergency shutdown procedure of the CEB direct combustion device when the system pressure is detected to exceed a second preset threshold higher than the first preset threshold.

9. The CEB waste heat recovery safety system according to claim 1, characterized in that, It also includes an oil and gas pretreatment unit, the outlet of which is connected to the inlet of the CEB direct combustion device to pretreat the exhaust gas entering the CEB direct combustion device.

10. A method for safe control of waste heat recovery using the system described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Real-time monitoring of pressure parameters in the premixing chamber and combustion chamber of the CEB direct combustion unit; S2. Under normal operating conditions, control the combined induced draft device to open the induced draft channel and close the emergency relief channel to introduce high-temperature flue gas into the waste heat recovery unit; S3. When the pressure parameter is detected to exceed the preset safety threshold, the combined induced draft device is controlled to open the emergency relief channel, so that the flue gas is directly discharged into the atmosphere.

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