A skid-mounted low-concentration gas flameless oxidation power generation system and method

Abstract

This application discloses a skid-mounted low-concentration methane flameless oxidation power generation system and method, relating to the field of efficient utilization technology of coal mine methane. The system includes a methane treatment module, a superheater, a power generation module, a flue gas purification module, and a waste steam treatment module, all of which are skid-mounted. The methane treatment module performs flameless oxidation on low-concentration methane to obtain high-temperature flue gas, which is then exchanged with low-temperature water to obtain low-temperature flue gas and saturated steam. The superheater heats the saturated steam to obtain superheated steam. The power generation module generates electricity based on the superheated steam, producing waste steam and electrical energy. The flue gas purification module purifies the low-temperature flue gas to obtain exhaust-ready flue gas. The waste steam treatment module treats the waste steam to obtain low-temperature water, which is then transported to the methane treatment module. This application solves the problems of poor utilization rate, environmental pollution, high project investment, and high operating costs associated with traditional methane flameless oxidation power generation.

Description

Technical Field

[0001] This application relates to the field of efficient utilization technology of coal mine gas, and in particular to a skid-mounted low-concentration gas flameless oxidation power generation system and method. Background Technology

[0002] To address coal mine safety issues, gas drainage is typically used to reduce methane concentration to below 1%, ensuring a safe level. However, during gas drainage, the limited variety of methods leads to significant air contamination and inconsistent drainage volumes. This results in a majority of the drained gas having a concentration below 30%, with low-concentration methane (below 8%) accounting for over 70% of the total. This low-concentration methane, falling within the explosive range, is difficult to stably combust using conventional methods and must be released into the atmosphere.

[0003] The main component of methane is gas, which has a greenhouse effect equivalent to 24.6 times that of CO2 and a destructive capacity to the ozone layer equivalent to 7 times that of CO2. Every year, a large amount of low-concentration methane is released but cannot be efficiently utilized, which not only causes a serious waste of limited non-renewable resources, but also exacerbates air pollution and the greenhouse effect. With the continuous progress of methane flameless oxidation power generation technology, thermal storage flameless oxidation power generation technology has gradually matured and been applied. Based on the technology of improving thermal storage capacity, low-concentration methane extracted from coal mines with a concentration of less than 8% can be mixed with exhaust methane or air to a concentration of 1.0%-1.2% for oxidation power generation, realizing the utilization of low-concentration methane. However, methane flameless oxidation power generation has the following problems: (1) poor utilization rate and pollution to the environment; (2) large investment: compared with general coalbed methane (gas) power generation projects, the investment is larger and the construction period is longer; (3) high operating cost: the daily maintenance is large, requiring professional technicians and equipment, which increases the cost of manpower and materials. At the same time, the wear and replacement of equipment will also bring certain cost pressure. Summary of the Invention

[0004] The purpose of this application is to provide a skid-mounted low-concentration gas flameless oxidation power generation system and method, which can solve the problems of poor utilization rate, environmental pollution, large project investment and high operating cost of traditional gas flameless oxidation power generation.

[0005] To achieve the above objectives, this application provides the following solution:

[0006] In a first aspect, this application provides a skid-mounted low-concentration gas flameless oxidation power generation system, comprising: a gas treatment module, a superheater, a power generation module, a flue gas purification module, and a waste steam treatment module, wherein the gas treatment module, the superheater, the power generation module, the flue gas purification module, and the waste steam treatment module all adopt a skid-mounted structure;

[0007] The gas treatment module is used to perform flameless oxidation of low-concentration gas to obtain high-temperature flue gas, and to exchange heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam; the temperature of the high-temperature flue gas is greater than the temperature of the low-temperature water, and the temperature of the high-temperature flue gas is greater than the temperature of the low-temperature flue gas.

[0008] The superheater is used to heat the saturated steam to obtain superheated steam;

[0009] The power generation module is used to generate electricity based on the superheated steam, obtaining exhaust steam and electrical energy;

[0010] The flue gas purification module is used to purify the low-temperature flue gas to obtain exhaustable flue gas;

[0011] The exhaust steam treatment module is used to process the exhaust steam to obtain low-temperature water, and then transport the low-temperature water to the gas treatment module.

[0012] Optionally, the number of gas treatment modules configured is determined based on the intake volume and concentration of low-concentration gas. Where n1 is the number of gas treatment modules configured. To round up, V is the intake volume of low-concentration methane, and C is the concentration of low-concentration methane.

[0013] The number of operating gas treatment modules is determined based on the intake volume and concentration of low-concentration gas. Where n2 is the number of gas treatment modules in operation;

[0014] One superheater corresponds to two gas treatment modules. The superheater is used to heat the saturated steam obtained by the two gas treatment modules corresponding to the superheater to obtain superheated steam.

[0015] Optionally, the gas treatment module includes: a gas pretreatment unit, a gas flameless oxidation device, and a waste heat boiler;

[0016] The gas pretreatment unit is used to pretreat low-concentration gas to obtain pretreated gas;

[0017] The gas flameless oxidation device is used to perform flameless oxidation on the pretreated gas to obtain high-temperature flue gas;

[0018] The waste heat boiler is used to exchange heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam, and to receive low-temperature water delivered by the waste steam treatment module.

[0019] Optionally, the gas pretreatment unit includes: a redundant safety control subunit, a multi-stage dehydration subunit, and a dynamic pressurization and regulation subunit connected in sequence;

[0020] The redundant safety control subunit includes: a first controller, a methane concentration sensor, and a pneumatic shut-off valve. The methane concentration sensor is installed at the air inlet of the multi-stage dehydration subunit, and the pneumatic shut-off valve is installed on the air inlet pipe of the multi-stage dehydration subunit. The methane concentration sensor is used to detect the methane concentration in low-concentration gas. The first controller is used to control the pneumatic shut-off valve to close when the methane concentration is greater than the upper limit of the methane concentration for a duration greater than the upper limit of the duration, so as to prevent low-concentration gas from entering the multi-stage dehydration subunit.

[0021] The multi-stage dewatering subunit includes: a coarse dewatering device, a fine dewatering device, and a self-cleaning filter connected in sequence;

[0022] The dynamic booster regulation subunit includes: a second controller, a dual-channel Roots booster, a pressure sensor, and an anti-surge return valve. The pressure sensor is installed at the outlet of the dual-channel Roots booster, and the anti-surge return valve is installed on a connecting pipe, which is used to connect the inlet and outlet of the dual-channel Roots booster. The pressure sensor is used to detect the pressure of the air at the outlet. The second controller is used to control the speed of the dual-channel Roots booster and the opening and closing of the anti-surge return valve based on the pressure. When the anti-surge return valve is opened, a portion of the air at the outlet of the dual-channel Roots booster flows back to the inlet of the dual-channel Roots booster.

[0023] Optionally, the methane concentration sensor includes: a laser methane sensor, an infrared sensor, and a catalytic combustion sensor;

[0024] The laser methane sensor is used to detect the methane concentration in low-concentration methane gas to obtain a first methane concentration.

[0025] The infrared sensor is used to detect the methane concentration in low-concentration methane gas to obtain a second methane concentration.

[0026] The catalytic combustion sensor is used to detect the methane concentration in low-concentration methane to obtain the third methane concentration.

[0027] The first controller is used to determine whether the absolute value of the difference between the first methane concentration and the third methane concentration is less than a preset difference, and obtain a first determination result. If the first determination result is yes, the first methane concentration is used as the methane concentration detected by the methane concentration sensor. If the first determination result is no, the controller determines whether the absolute value of the difference between the second methane concentration and the third methane concentration is less than a preset difference, and obtains a second determination result. If the second determination result is yes, the second methane concentration is used as the methane concentration detected by the methane concentration sensor.

[0028] Optionally, the gas flameless oxidation device includes: a third controller, an oxidation chamber, an outer insulation layer, and auxiliary heating components;

[0029] The outer insulation layer encloses the oxidation chamber, and molten salt is filled between the outer insulation layer and the oxidation chamber;

[0030] The third controller is used to control the auxiliary heating component to turn on when the concentration of gas after pretreatment is less than a preset concentration, thereby raising the temperature of the oxidation chamber to a preset temperature; wherein the auxiliary heating component adopts fuel-assisted heating or electric-assisted heating.

[0031] Optionally, the heating surface in the flue gas inlet section of the waste heat boiler is made of bare tube, and the heating surface in the flue gas outlet section of the waste heat boiler is made of corrugated tube or finned tube.

[0032] Optionally, when the number of gas treatment modules is less than or equal to 3, the power generation module adopts a power generation device based on Rankine cycle low-temperature waste heat power generation or a power generation device based on screw expander power generation; when the number of gas treatment modules is greater than or equal to 4, the power generation module adopts a power generation device based on steam turbine power generation.

[0033] Optionally, the exhaust steam treatment module includes: a condensation unit and a water treatment unit;

[0034] The condensation unit is used to condense the exhaust steam to obtain condensate.

[0035] The water treatment unit is used to treat the condensate to obtain low-temperature water, and then transport the low-temperature water to the gas treatment module.

[0036] Secondly, this application provides a skid-mounted method for low-concentration gas flameless oxidation power generation, which operates based on the aforementioned skid-mounted low-concentration gas flameless oxidation power generation system, including:

[0037] The gas treatment module performs flameless oxidation on low-concentration gas to obtain high-temperature flue gas, and then exchanges heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam; the temperature of the high-temperature flue gas is higher than the temperature of the low-temperature water, and the temperature of the high-temperature flue gas is higher than the temperature of the low-temperature flue gas.

[0038] The superheater heats the saturated steam to obtain superheated steam;

[0039] The power generation module generates electricity based on the superheated steam, obtaining exhaust steam and electrical energy;

[0040] The flue gas purification module purifies the low-temperature flue gas to obtain exhaust-ready flue gas.

[0041] The exhaust steam treatment module processes the exhaust steam to obtain low-temperature water, and then transports the low-temperature water to the gas treatment module.

[0042] According to the specific embodiments provided in this application, this application has the following technical effects:

[0043] This application provides a skid-mounted low-concentration gas flameless oxidation power generation system and method. The gas treatment module performs flameless oxidation on low-concentration gas to obtain high-temperature flue gas, and exchanges heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam. The superheater heats the saturated steam to obtain superheated steam. The power generation module generates electricity based on the superheated steam to obtain exhaust steam and electrical energy. The flue gas purification module purifies the low-temperature flue gas to obtain exhaustable flue gas. The exhaust steam treatment module treats the exhaust steam to obtain low-temperature water, and then transports the low-temperature water to the gas treatment module. This application, by incorporating a waste steam treatment module, can reprocess the waste steam obtained after power generation into low-temperature water, which is then fed into a gas treatment module for recycling, thereby improving utilization efficiency. Furthermore, by incorporating a flue gas purification module, the low-temperature flue gas can be treated into usable flue gas before being released, avoiding environmental pollution and making it more environmentally friendly. Moreover, by adopting a skid-mounted structure for the gas treatment module, superheater, power generation module, flue gas purification module, and waste steam treatment module, flexible arrangement and easy transportation to a coal mine for installation are possible. Compared to traditional flameless gas oxidation power generation schemes where each module is integrated into a single unit, this approach eliminates the need for relocation to a specific coal mine. Constructing individual modules reduces investment and shortens the construction period. Furthermore, since each module uses a skid-mounted structure, they are independent and can be partially repaired. Compared to traditional gas-fired flameless oxidation power generation where modules are integrated into a single unit requiring overall shutdown for maintenance, each module can be repaired independently without affecting operation. This reduces maintenance workload and allows for the replacement of only faulty modules, eliminating the need to replace the entire system, thus lowering operating costs. This addresses the problems of poor utilization, environmental pollution, high investment, and high operating costs associated with traditional gas-fired flameless oxidation power generation. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a schematic diagram of a skid-mounted low-concentration gas flameless oxidation power generation system provided in Embodiment 1 of this application.

[0046] Figure 2 This is a schematic flowchart of a skid-mounted low-concentration gas flameless oxidation power generation method provided in Embodiment 2 of this application. Detailed Implementation

[0047] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0048] Example 1

[0049] Gas, as a high-quality energy source, has a calorific value of approximately 35,000 kJ / Nm³. 3 Coalbed methane (CBM) is comparable to conventional natural gas and can be used as fuel and chemical feedstock. However, because oxygen is a flammable additive, its introduction increases the explosion hazard of CBM, posing significant challenges to its processing and transportation. Currently, the types, proportions, utilization rates, and main utilization methods of extracted CBM are as follows: high-concentration CBM (>30%) accounts for approximately 6%, with a utilization rate exceeding 90%. Low-concentration CBM accounts for approximately 94%, but its utilization rate is below 35%. Due to the extremely low concentration of CBM in low-concentration CBM, its utilization is difficult. Its main utilization methods are regenerative thermal oxidation and co-combustion of high-concentration CBM for power generation. These methods also have relatively low utilization rates, resulting in most low-concentration CBM being directly released into the atmosphere, causing enormous resource waste and significant environmental damage.

[0050] To address the problems of poor utilization rate, environmental pollution, high investment and operating costs associated with traditional gas-fired flameless oxidation power generation systems, this embodiment provides a skid-mounted low-concentration gas-fired flameless oxidation power generation system, such as... Figure 1As shown, the system includes a gas treatment module, a superheater, a power generation module, a flue gas purification module, and a waste steam treatment module. All of these modules adopt a skid-mounted structure. A skid-mounted structure integrates functional components onto a single base, facilitating overall installation and relocation. It offers advantages such as mobility, small size, minimal footprint, and ease of relocation. In this embodiment, the gas treatment module, superheater, power generation module, flue gas purification module, and waste steam treatment module are installed on the base, making them independent of each other and enabling independent installation, relocation, and maintenance.

[0051] The gas treatment module is used to perform flameless oxidation on low-concentration gas (concentration <8%) to obtain high-temperature flue gas, and then exchange heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam. The temperature of the high-temperature flue gas is higher than that of the low-temperature water, and the temperature of the high-temperature flue gas is higher than that of the low-temperature flue gas.

[0052] A superheater is used to heat saturated steam to obtain superheated steam.

[0053] The power generation module is used to generate electricity based on superheated steam, producing exhaust steam (low-grade steam with a certain pressure and temperature that is discharged after superheated steam has done work) and electrical energy.

[0054] The flue gas purification module is used to purify low-temperature flue gas to obtain exhaust-ready flue gas.

[0055] The exhaust steam treatment module is used to process exhaust steam to obtain low-temperature water, and then transport the low-temperature water to the gas treatment module.

[0056] The following is a detailed description of each module in this embodiment:

[0057] (I) Gas Treatment Module

[0058] This embodiment designs the configuration quantity (i.e., the number of gas treatment modules to be constructed) and the operating quantity (i.e., the number of gas treatment modules to be operated simultaneously) of the gas treatment modules based on the product of the gas intake volume V and the concentration C of the low-concentration gas. The configuration quantity refers to how many gas treatment modules need to be configured for the low-concentration gas generated in the current coal mine, and the operating quantity refers to how many gas treatment modules need to be turned on for the low-concentration gas that needs to be treated at the current time. The operating quantity is less than the configuration quantity. By setting the configuration quantity and operating quantity of the gas treatment modules, the power of the flameless gas oxidation device in the gas treatment module can be matched with the low-concentration gas.

[0059] The number of gas treatment modules configured is determined based on the intake volume and concentration of low-concentration gas. Where n1 is the number of gas treatment modules configured. To round up, V represents the intake volume of low-concentration methane, and C represents the concentration of low-concentration methane. For example, when 10×V×C≤4500, one methane treatment module is configured; when 4500<10×V×C≤9000, two methane treatment modules are configured.

[0060] To improve efficiency, when the number of gas treatment modules is one, it is recommended to use methods such as direct steam supply, absorption heating / cooling, vacuum phase change direct heating units, and absorption heat pumps to utilize the heat from the high-temperature flue gas generated by the flameless gas oxidation device in the gas treatment module. Direct steam supply refers to directly heating water with the heat from the high-temperature flue gas generated by the flameless gas oxidation device through a heat exchanger to generate steam for industrial production or domestic use. Direct absorption heating / cooling refers to using the heat from the high-temperature flue gas generated by the flameless gas oxidation device as a driving heat source to drive an absorption cooling or heating cycle. Direct vacuum phase change direct heating units refer to directly heating a working medium with the heat from the high-temperature flue gas generated by the flameless gas oxidation device in a vacuum environment, causing it to undergo a phase change, thereby achieving efficient heat transfer and utilization. Direct absorption heat pumps refer to using the heat from the high-temperature flue gas generated by the flameless gas oxidation device as a driving energy source, pumping the heat from a low-temperature heat source to a high-temperature heat user through an absorption cycle, thereby achieving upgraded heat utilization.

[0061] Based on the intake volume V and concentration C of the low-concentration methane, the methane treatment modules can operate independently (i.e., only one methane treatment module is in operation) or in combination (i.e., at least two methane treatment modules are in operation). The number of operating methane treatment modules is determined based on the intake volume and concentration of the low-concentration methane. Where n2 is the number of gas treatment modules in operation.

[0062] This embodiment of a gas treatment module consists of a gas pretreatment unit, a gas flameless oxidation device, and a waste heat boiler. The gas pretreatment unit is used to improve gas quality and increase power generation efficiency.

[0063] In this embodiment, the gas treatment module includes a gas pretreatment unit, a gas flameless oxidation device, and a waste heat boiler. The gas pretreatment unit is used to pretreat low-concentration gas to obtain pretreated gas. The gas flameless oxidation device is used to perform flameless oxidation on the pretreated gas to obtain high-temperature flue gas. The waste heat boiler is used to exchange heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam, and to receive low-temperature water delivered by the waste steam treatment module.

[0064] The following is a detailed introduction to the gas pretreatment unit, the flameless gas oxidation device, and the waste heat boiler:

[0065] (1) Gas pretreatment unit

[0066] The gas pretreatment unit in this embodiment integrates redundant safety control, multi-stage dehydration, and dynamic pressurization regulation functions to solve problems such as safety hazards, incomplete dehydration, and unstable pressurization in the utilization of low-concentration gas. Specifically, the gas pretreatment unit in this embodiment includes: a redundant safety control subunit, a multi-stage dehydration subunit, and a dynamic pressurization regulation subunit connected in sequence.

[0067] The redundant safety control subunit in this embodiment has a rapid shut-off function. Specifically, it is equipped with a pneumatic shut-off valve (action time ≤ 0.5s). When the methane concentration in low-concentration gas exceeds 10% for a long time (e.g., duration > 5min), the pneumatic shut-off valve is controlled to close and cut off the gas intake.

[0068] In this embodiment, the redundant safety control subunit includes a first controller, a methane concentration sensor, and a pneumatic shut-off valve. The methane concentration sensor is installed at the air inlet of the multi-stage dehydration subunit, and the pneumatic shut-off valve is installed on the air inlet pipe of the multi-stage dehydration subunit. The methane concentration sensor is used to detect the methane concentration in low-concentration gas. The first controller is used to control the pneumatic shut-off valve to close when the methane concentration is greater than the upper limit of the methane concentration (e.g., 10%) for a duration greater than the upper limit of the duration (e.g., 5 minutes), so as to prevent low-concentration gas from entering the multi-stage dehydration subunit.

[0069] In this embodiment, the methane concentration sensor employs a three-stage concentration monitoring system, specifically consisting of a laser methane sensor (response time < 1s), an infrared sensor, and a catalytic combustion sensor. The methane concentration detected by the catalytic combustion sensor is used as a standard to calibrate the methane concentrations detected by the laser and infrared sensors. If the positive or negative deviation between the methane concentrations detected by the laser and catalytic combustion sensors is less than 5%, the methane concentration detected by the laser sensor is used as the final output methane concentration. Subsequently, the first controller uses this final output methane concentration to control the pneumatic shut-off valve. Otherwise, the laser methane sensor is considered damaged. Similarly, if the positive or negative deviation between the methane concentrations detected by the infrared and catalytic combustion sensors is less than 5%, the methane concentration detected by the infrared sensor is used as the final output methane concentration. Subsequently, the first controller uses this final output methane concentration to control the pneumatic shut-off valve. Otherwise, the infrared sensor is also considered damaged. In this case, both the laser and infrared sensors are damaged simultaneously, requiring system shutdown for maintenance.

[0070] In this embodiment, the methane concentration sensor includes a laser methane sensor, an infrared sensor, and a catalytic combustion sensor. The laser methane sensor detects the methane concentration in low-concentration methane gas to obtain a first methane concentration. The infrared sensor detects the methane concentration in low-concentration methane gas to obtain a second methane concentration. The catalytic combustion sensor detects the methane concentration in low-concentration methane gas to obtain a third methane concentration. The first controller determines whether the absolute value of the difference between the first and third methane concentrations is less than a preset difference (e.g., 5%) to obtain a first determination result. If the first determination result is yes, the first methane concentration is used as the methane concentration detected by the methane concentration sensor. If the first determination result is no, the controller determines whether the absolute value of the difference between the second and third methane concentrations is less than a preset difference (e.g., 5%) to obtain a second determination result. If the second determination result is yes, the second methane concentration is used as the methane concentration detected by the methane concentration sensor. If the second determination result is no, it is considered that both the laser methane sensor and the infrared sensor are damaged and require shutdown maintenance.

[0071] The redundant safety control subunit in this embodiment also has a nitrogen injection function. When the methane concentration detected by the methane concentration sensor is greater than the upper limit of the methane concentration for a longer period of time, after controlling the pneumatic shut-off valve to close, high-pressure nitrogen (purity ≥99.999%) can be injected into the air intake pipe instantly to dilute the low-concentration gas and reduce the methane concentration in the low-concentration gas to a safe concentration, which is the concentration less than the upper limit of the methane concentration.

[0072] The multi-stage dehydration subunit in this embodiment includes coarse dehydration, fine dehydration, and a self-cleaning filter.

[0073] In this embodiment, the multi-stage dehydration subunit includes a coarse dehydration device, a fine dehydration device, and a self-cleaning filter connected in sequence. The main purpose of the coarse dehydration device is to remove most of the liquid water and some of the gaseous water from low-concentration methane, reducing the humidity of the methane. For example, coarse dehydration can be performed using cyclone separators and condensation methods. The fine dehydration device further reduces the moisture content in low-concentration methane based on the coarse dehydration device, achieving a higher degree of dryness. For example, fine dehydration can be performed using absorption dehydration and desiccant dehydration. The self-cleaning filter is used to remove impurities from low-concentration methane, such as dust, tar, and acids, to protect downstream equipment from contamination and blockage, while ensuring the cleanliness of the methane. For example, the self-cleaning filter mainly consists of a filter screen, a backwashing device, and a differential pressure controller. When methane passes through the filter screen, impurities are intercepted. As impurities accumulate, the pressure difference across the filter screen gradually increases. When the pressure difference reaches a set value, the differential pressure controller sends a signal to activate the backwashing device to clean the filter screen, flushing away and discharging the intercepted impurities, thus restoring the filter screen's filtration performance.

[0074] The dynamic booster regulation subunit of this embodiment includes a dual-channel Roots booster, a pressure closed-loop control function for controlling the speed of the dual-channel Roots booster, and an anti-surge function based on an anti-surge return valve to prevent surge in the dual-channel Roots booster. The dual-channel Roots booster operates in parallel with two Roots blowers to boost gas pressure. The pressure closed-loop control function monitors the outlet pressure in real time by installing a pressure sensor at the outlet of the dual-channel Roots booster and transmits the detected outlet pressure to the controller. The controller adjusts the pressure based on the set outlet pressure and the detected outlet pressure via P. ID (Proportional-Integral-Derivative) control automatically adjusts the speed of the dual-channel Roots booster, thereby achieving precise control of the outlet pressure. This ensures stable gas pressure during transportation and utilization, avoiding equipment failures and safety hazards caused by pressure fluctuations. The anti-surge function opens the anti-surge return valve when gas flow or pressure fluctuations may cause surge in the dual-channel Roots booster. This returns a portion of the gas from the outlet to the inlet, increasing the intake volume and preventing surge.

[0075] In this embodiment, the dynamic booster regulation subunit includes: a second controller, a dual-channel Roots booster, a pressure sensor, and an anti-surge return valve. The pressure sensor is installed at the outlet of the dual-channel Roots booster, and the anti-surge return valve is installed on the connecting pipe, which is used to connect the inlet and outlet of the dual-channel Roots booster. The pressure sensor is used to detect the pressure of the air at the outlet. The second controller is used to control the speed of the dual-channel Roots booster based on the pressure (specifically, calculating the difference between the pressure and the preset pressure target value, and performing PID control based on the difference) and the opening and closing of the anti-surge return valve (specifically, controlling the anti-surge return valve to open when the pressure change value is greater than the preset change value). When the anti-surge return valve is opened, part of the air at the outlet of the dual-channel Roots booster flows back to the inlet of the dual-channel Roots booster.

[0076] In this embodiment, dehydration can be performed first and then pressure regulation can be applied. In this case, the multi-stage dehydration subunit is placed before the dynamic pressure regulation subunit. Alternatively, pressure regulation can be performed first and then dehydration can be applied. In this case, the dynamic pressure regulation subunit is placed before the multi-stage dehydration subunit.

[0077] (2) Gas-fired flameless oxidation unit

[0078] The flameless gas oxidation device in this embodiment has a power of 3000-4000kW, with a 10% power redundancy, and can operate stably when the concentration of low-concentration gas is in the range of 1%-8%. The corresponding gas intake provided by the gas treatment module is 5000-30000 Nm³. 3 / h, which can adapt to changes in the intake volume and concentration of gas after pretreatment.

[0079] The gas-fired flameless oxidation device can employ direct current jet flameless oxidation, swirling jet flameless oxidation, or porous media regenerative oxidation. Molten salt is filled between the oxidation chamber and the external insulation layer to enhance the device's heat storage capacity. Furthermore, the device features a built-in closed-loop controlled ignition system and auxiliary heating system to ensure a safe and stable oxidation reaction. The closed-loop control of the ignition system involves monitoring combustion through devices such as detonation sensors, transmitting combustion status signals to the control unit. The control unit then adjusts parameters such as ignition advance angle and ignition energy in real time based on the received signals, ensuring that the ignition timing and energy are always optimal. This guarantees stable ignition and maintains good combustion efficiency. The auxiliary heating system is activated in the early stages of the oxidation reaction or when the gas concentration is low, as the heat generated by the gas oxidation process itself may be insufficient to maintain the required reaction temperature. In such cases, the auxiliary heating system inputs additional heat into the gas-fired flameless oxidation device, allowing the reaction system to quickly reach or maintain a suitable reaction temperature, ensuring the smooth progress of the oxidation reaction.

[0080] The auxiliary heating system operates as follows: When the concentration of pretreated gas is less than 4.5%, the temperature of the oxidation chamber needs to be increased to 800℃ via the auxiliary heating system. The auxiliary heating system can employ at least one of fuel-assisted or electric auxiliary heating. Fuel-assisted heating refers to burner heating, where the fuel can be gasoline, diesel, methanol, natural gas, etc. The fuel is ignited through the ignition system to raise the temperature of the oxidation chamber. When the temperature of the oxidation chamber reaches 800℃, the ignition system of the flameless gas oxidation device is activated, and pretreated gas is then introduced into the oxidation chamber. The gas is ignited for flameless oxidation. When the concentration of pretreated gas is greater than or equal to 4.5%, it needs to be purged by a dual-channel Roots booster. When methane cannot be detected, the ignition system of the gas flameless oxidation device is turned on, and the pretreated gas is introduced into the oxidation chamber and ignited. The flow rate and pressure of the pretreated gas are gradually changed to increase the high-temperature flue gas reflux ratio, so that the gas flameless oxidation device is in a flameless oxidation state for flameless oxidation. In particular, the concentration of pretreated gas when it can be directly ignited is 4.5% to 5.0%.

[0081] In this embodiment, the gas flameless oxidation device includes: a third controller, an oxidation chamber, an outer insulation layer, and an auxiliary heating component. The outer insulation layer covers the oxidation chamber, and molten salt is filled between the outer insulation layer and the oxidation chamber. The third controller is used to control the auxiliary heating component to turn on when the concentration of gas after pretreatment is less than a preset concentration (which can be 4.5%), thereby raising the temperature of the oxidation chamber to a preset temperature (which can be 800°C). The auxiliary heating component adopts fuel-assisted heating or electric-assisted heating.

[0082] (3) Waste heat boiler

[0083] Waste heat boilers can be saturated steam boilers with a rated evaporation capacity of 4-5 tons. The heating surfaces of a waste heat boiler refer to the surfaces of components that can absorb waste heat and generate steam or hot water. In waste heat boilers, the heating surfaces near the high-temperature flue gas inlet section use bare tubes, while the heating surfaces near the low-temperature flue gas outlet section use corrugated tubes or finned tubes, which can enhance the heat transfer effect. For users with heating needs, the heat source can be directly the saturated steam generated by the waste heat boiler.

[0084] In this embodiment, the heating surface of the waste heat boiler at the flue gas inlet section is made of bare tube, and the heating surface of the waste heat boiler at the flue gas outlet section is made of corrugated tube or finned tube.

[0085] (II) Superheater

[0086] In this embodiment, saturated steam generation and superheated steam generation are handled by two separate modules. Specifically, saturated steam is generated through a waste heat boiler, and superheated steam is generated through a superheater. This approach offers greater flexibility and reduces costs because if only the waste heat boiler were used to generate superheated steam, its structure would be more complex and its cost higher. The heat required by the superheater can be provided by the high-temperature flue gas generated by the gas treatment module.

[0087] Two gas treatment modules are configured with one superheater. In this embodiment, one superheater corresponds to two gas treatment modules. The superheater is used to heat the saturated steam obtained by the two gas treatment modules corresponding to the superheater to obtain superheated steam.

[0088] (III) Power Generation Module

[0089] The power generation module in this embodiment can adopt Rankine cycle low-temperature waste heat power generation technology, screw expander power generation technology, or steam turbine power generation technology. When the number of gas treatment modules n1 ≤ 3, Rankine cycle low-temperature waste heat power generation technology or screw expander power generation technology can be adopted. When the number of gas treatment modules n1 ≥ 4, steam turbine power generation technology can be adopted.

[0090] In this embodiment, when the number of gas treatment modules is less than or equal to 3, the power generation module adopts a power generation device based on Rankine cycle low-temperature waste heat power generation or a power generation device based on screw expander power generation; when the number of gas treatment modules is greater than or equal to 4, the power generation module adopts a power generation device based on steam turbine power generation.

[0091] (iv) Flue gas purification module

[0092] The flue gas purification module is used to purify low-temperature flue gas, remove harmful substances from the low-temperature flue gas, and obtain exhaustable flue gas that meets emission standards.

[0093] (V) Exhaust Steam Treatment Module

[0094] The exhaust steam treatment module in this embodiment includes a condensation unit and a water treatment unit. The condensation unit is used to condense the exhaust steam into condensate, and the water treatment unit is used to treat the condensate, adjust the water quality of the condensate, and remove impurities, pollutants or harmful substances from the water.

[0095] In this embodiment, the exhaust steam treatment module includes a condensation unit and a water treatment unit. The condensation unit is used to condense the exhaust steam to obtain condensate, and the water treatment unit is used to treat the water quality of the condensate to obtain low-temperature water, and then transport the low-temperature water to the gas treatment module, specifically to the waste heat boiler in the gas treatment module.

[0096] The low-concentration methane flameless oxidation power generation system of this embodiment includes a methane pretreatment unit, a methane flameless oxidation device, a waste heat boiler, a flue gas purification module, a superheater, a power generation module, a condensation unit, and a water treatment unit. It can achieve energy conservation and emission reduction in coal mines. Its working process is as follows: low-concentration methane undergoes pretreatment in the methane pretreatment unit to meet the intake requirements of the methane flameless oxidation device. The pretreated methane then enters the methane flameless oxidation device for flameless oxidation, resulting in high-temperature flue gas. The high-temperature flue gas generated after flameless oxidation enters the waste heat boiler, where it exchanges heat with low-temperature water. The resulting low-temperature flue gas then passes through the flue gas purification unit. The purification module performs purification treatment to meet the emission standards of the corresponding region (i.e., the region where the low-concentration gas flameless oxidation power generation system of this embodiment is located). The resulting exhaust gas is then discharged. The low-temperature water in the waste heat boiler absorbs heat and vaporizes to produce saturated steam. The saturated steam enters the superheater and is further heated to become superheated steam. The superheated steam that meets the power generation requirements is sent to the power generation module to generate electricity. The exhaust steam obtained after the superheated steam does work is condensed by the condensation unit. The resulting condensate is sent to the water treatment unit. After the water treatment unit treats the water to meet the standards, the resulting low-temperature water is sent back to the waste heat boiler for repeated circulation.

[0097] Among them, the gas inlet requirements for the gas flameless oxidation unit can be: gas inlet volume > 5000 Nm³ 3 / h, concentration >1%, moisture content ≤40g / Nm 3 Impurity particle size ≤ 8μm, impurity content ≤ 50mg / Nm 3 The pressure is 3–20 kPa, and the pressure change rate is ≤1 kPa / min.

[0098] The emission standards for flue gas can be the emission standards of the corresponding region or the national standards. Generally, the standard for this region is: NOx ≤ 80 mg / m³. 3 The key control areas are those with NOx ≤ 100 mg / m³. 3 SO2 ≤ 50 mg / m³ 3 Particulate matter ≤10mg / m³ 3 .

[0099] The water quality indicators and standards for water treatment units are as follows: For medium-pressure boilers, hardness: the hardness of the feedwater should not exceed 3 μmol / L; conductivity: the conductivity of the feedwater should not exceed 5 μS / cm; phosphate content: the phosphate content of the feedwater is generally controlled between 5 and 15 mg / L; silica content: the silica content of the feedwater should not exceed 2 mg / L; pH value: the pH value of the feedwater should be controlled between 8.5 and 9.5, as excessively high or low pH values ​​will have adverse effects on boiler equipment; dissolved oxygen concentration: the dissolved oxygen concentration should be within a reasonable range to prevent corrosion of boiler equipment.

[0100] The core of this embodiment is modular design, skid-mounted combination, and multi-module integration. Each module adopts a skid-mounted structure, which is easy to transport and install, convenient to arrange, and can be disassembled and transported at any time. It is especially suitable for areas with complex terrain and has low investment costs. Furthermore, through matching and dynamic control (setting the configuration and operation of the gas treatment modules), the gas treatment modules can be matched with the gas intake volume.

[0101] This embodiment also includes a control module. The control module collects signals from each module, makes judgments based on target requirements, and issues instructions to ensure the low-concentration gas flameless oxidation power generation system maintains high efficiency. Specifically, the control module collects the concentration and intake volume of pretreated gas generated by the gas pretreatment unit, the temperature and flow rate of high-temperature flue gas generated by the gas flameless oxidation device, the temperature, pressure, and flow rate of saturated steam generated by the waste heat boiler, the temperature, pressure, and flow rate of superheated steam generated by the superheater, and the flue gas indicators (including nitrogen oxide content, sulfur oxide content, carbon monoxide content, and carbon dioxide content) of the exhaust gas generated by the flue gas purification module. The power generation of the module, the temperature of the generated exhaust steam, and the water quality indicators of the low-temperature water produced by the water treatment unit are all considered. When operating with the superheater, the temperature, pressure, and flow rate of the superheated steam generated by the superheater and the temperature, pressure, and flow rate of the saturated steam generated by the waste heat boiler are used as target parameters. Combustion conditions are adjusted by changing the parameters of the waste heat boiler. Specifically, if the temperature and pressure of the saturated steam or superheated steam are slightly higher than the rated parameters (i.e., the difference is less than the preset value), the exhaust loss can be increased by using a purge fan, thereby reducing the effective heat utilization. If the temperature and pressure of the saturated steam or superheated steam are significantly higher than the rated parameters (i.e., the difference is greater than the preset value), then... By controlling the valve opening of the intake pipe, the amount of pretreated gas entering the flameless gas oxidation unit is reduced, thereby lowering the thermal power of the unit. If the temperature and pressure of saturated steam or superheated steam are lower than the rated parameters, the amount of pretreated gas entering the unit is adjusted to increase combustion power, i.e., increase the thermal power of the unit, thus obtaining qualified steam quality. The amount of pretreated gas entering the unit is also adjusted based on the temperature and flow rate of the high-temperature flue gas generated by the unit. If the temperature is low or the flow rate is low, the valve opening of the intake pipe is increased to improve the efficiency of the gas entering the unit. The pre-treated gas intake volume is adjusted as follows: When the temperature or flow rate is high, the valve opening of the intake pipe is reduced to decrease the pre-treated gas intake volume into the gas flameless oxidation unit; the gas intake volume or circulating water volume of the gas flameless oxidation unit is finely adjusted according to the temperature, flow rate, and pressure of the saturated steam generated by the waste heat boiler; based on the pre-treated gas intake volume generated by the gas pre-treatment unit, the temperature of the high-temperature flue gas generated by the gas flameless oxidation unit, the temperature, pressure, and flow rate of the saturated steam generated by the waste heat boiler, the temperature of the low-temperature flue gas generated, the power generation of the power generation module, and the flue gas indicators of the exhaust gas generated by the flue gas purification module, with a 90m³... 3Using the target parameter of generating 200 kWh of electricity from pure gas, the optimal operating conditions were selected. Furthermore, by comparing the self-consumption under various operating conditions, the operating parameters used under the conditions of maximum power generation and minimum self-consumption were selected as the economic operating parameters. These economic operating parameters include the intake volume of pretreated gas from the gas pretreatment unit, the temperature of the high-temperature flue gas from the gas flameless oxidation device, the temperature, pressure, and flow rate of the saturated steam from the waste heat boiler, and the temperature of the generated low-temperature flue gas. Among these, the temperature, pressure, and flow rate of the saturated steam from the waste heat boiler are indicator parameters, while the remaining parameters are input parameters for adjustment. In actual operation control, these parameters are kept as consistent as possible to shorten the combustion optimization adjustment cycle. At this point, the control module has a self-learning function and can provide the optimal operating curve based on historical operating data, providing guidance for the actual operation of the low-concentration gas flameless oxidation power generation system.

[0102] This embodiment is a system that uses low-concentration methane generated during coal mining to generate electricity. It can fully realize the efficient on-site utilization of low-concentration methane, solve the problems of on-site methane consumption and winter heating in coal mines, and help coal production save energy and reduce carbon emissions. To address the low power generation efficiency of traditional flameless gas oxidation power generation, which involves mixing methane concentration to 1.2%, some heat is carried away by the air, resulting in low thermal efficiency and consequently low power generation efficiency. This embodiment uses low-concentration methane directly without mixing, thus improving power generation efficiency. Furthermore, to address the concentration fluctuation issue in traditional flameless gas oxidation power generation, which requires a relatively stable methane concentration, excessive fluctuations in methane concentration during actual operation can easily lead to protective shutdowns or a significant drop in power generation efficiency. In addition, the unstable concentration of methane extracted from underground mines can cause fluctuations in the methane concentration entering the flameless gas oxidation unit, affecting the stability of the oxidation reaction and power generation efficiency. This embodiment solves the concentration fluctuation problem by setting the number and operation of methane treatment modules and including a methane pretreatment unit, which provides a relatively stable methane and methane concentration to the flameless gas oxidation unit.

[0103] Example 2

[0104] This embodiment provides a skid-mounted, low-concentration methane flameless oxidation power generation method, which operates based on the skid-mounted, low-concentration methane flameless oxidation power generation system described in Embodiment 1. Figure 2 As shown, it includes:

[0105] S1: The gas treatment module performs flameless oxidation on low-concentration gas to obtain high-temperature flue gas, and exchanges heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam; the temperature of the high-temperature flue gas is greater than the temperature of the low-temperature water, and the temperature of the high-temperature flue gas is greater than the temperature of the low-temperature flue gas.

[0106] S2: The superheater heats the saturated steam to obtain superheated steam.

[0107] S3: The power generation module generates electricity based on the superheated steam, obtaining exhaust steam and electrical energy.

[0108] S4: The flue gas purification module purifies the low-temperature flue gas to obtain exhaustable flue gas.

[0109] S5: The exhaust steam treatment module processes the exhaust steam to obtain low-temperature water, and then transports the low-temperature water to the gas treatment module.

[0110] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0111] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A skid-mounted, low-concentration methane flameless oxidation power generation system, characterized in that, include: The gas treatment module, superheater, power generation module, flue gas purification module, and exhaust steam treatment module are all skid-mounted. The gas treatment module is used to perform flameless oxidation of low-concentration gas to obtain high-temperature flue gas, and to exchange heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam; the temperature of the high-temperature flue gas is greater than the temperature of the low-temperature water, and the temperature of the high-temperature flue gas is greater than the temperature of the low-temperature flue gas. The superheater is used to heat the saturated steam to obtain superheated steam; The power generation module is used to generate electricity based on the superheated steam, obtaining exhaust steam and electrical energy; The flue gas purification module is used to purify the low-temperature flue gas to obtain exhaustable flue gas; The exhaust steam treatment module is used to treat the exhaust steam to obtain low-temperature water, and then transport the low-temperature water to the gas treatment module. The number of gas treatment modules configured is determined based on the intake volume and concentration of low-concentration gas. ,in, The number of gas treatment modules configured. To round up, For low-concentration methane intake, The concentration of low-concentration methane; The number of operating gas treatment modules is determined based on the intake volume and concentration of low-concentration gas. ,in, This represents the number of gas processing modules in operation.

2. The skid-mounted low-concentration gas flameless oxidation power generation system according to claim 1, characterized in that, One superheater corresponds to two gas treatment modules. The superheater is used to heat the saturated steam obtained by the two gas treatment modules corresponding to the superheater to obtain superheated steam.

3. The skid-mounted low-concentration gas flameless oxidation power generation system according to claim 1, characterized in that, The gas treatment module includes: a gas pretreatment unit, a gas flameless oxidation device, and a waste heat boiler; The gas pretreatment unit is used to pretreat low-concentration gas to obtain pretreated gas; The gas flameless oxidation device is used to perform flameless oxidation on the pretreated gas to obtain high-temperature flue gas; The waste heat boiler is used to exchange heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam, and to receive low-temperature water delivered by the waste steam treatment module.

4. The skid-mounted low-concentration gas flameless oxidation power generation system according to claim 3, characterized in that, The gas pretreatment unit includes: a redundant safety control subunit, a multi-stage dehydration subunit, and a dynamic pressurization and regulation subunit connected in sequence; The redundant safety control subunit includes: a first controller, a methane concentration sensor, and a pneumatic shut-off valve. The methane concentration sensor is installed at the air inlet of the multi-stage dehydration subunit, and the pneumatic shut-off valve is installed on the air inlet pipe of the multi-stage dehydration subunit. The methane concentration sensor is used to detect the methane concentration in low-concentration gas. The first controller is used to control the pneumatic shut-off valve to close when the methane concentration is greater than the upper limit of the methane concentration for a duration greater than the upper limit of the duration, so as to prevent low-concentration gas from entering the multi-stage dehydration subunit. The multi-stage dewatering subunit includes: a coarse dewatering device, a fine dewatering device, and a self-cleaning filter connected in sequence; The dynamic booster regulation subunit includes: a second controller, a dual-channel Roots booster, a pressure sensor, and an anti-surge return valve. The pressure sensor is installed at the outlet of the dual-channel Roots booster, and the anti-surge return valve is installed on a connecting pipe, which is used to connect the inlet and outlet of the dual-channel Roots booster. The pressure sensor is used to detect the pressure of the air at the outlet. The second controller is used to control the speed of the dual-channel Roots booster and the opening and closing of the anti-surge return valve based on the pressure. When the anti-surge return valve is opened, a portion of the air at the outlet of the dual-channel Roots booster flows back to the inlet of the dual-channel Roots booster.

5. The skid-mounted low-concentration gas flameless oxidation power generation system according to claim 4, characterized in that, The methane concentration sensor includes: a laser methane sensor, an infrared sensor, and a catalytic combustion sensor; The laser methane sensor is used to detect the methane concentration in low-concentration methane gas to obtain a first methane concentration. The infrared sensor is used to detect the methane concentration in low-concentration methane gas to obtain a second methane concentration. The catalytic combustion sensor is used to detect the methane concentration in low-concentration methane to obtain the third methane concentration. The first controller is used to determine whether the absolute value of the difference between the first methane concentration and the third methane concentration is less than a preset difference, and obtain a first determination result. If the first determination result is yes, the first methane concentration is used as the methane concentration detected by the methane concentration sensor. If the first determination result is no, the controller determines whether the absolute value of the difference between the second methane concentration and the third methane concentration is less than a preset difference, and obtains a second determination result. If the second determination result is yes, the second methane concentration is used as the methane concentration detected by the methane concentration sensor.

6. The skid-mounted low-concentration gas flameless oxidation power generation system according to claim 3, characterized in that, The gas-fired flameless oxidation device includes: a third controller, an oxidation chamber, an outer insulation layer, and auxiliary heating components; The outer insulation layer encloses the oxidation chamber, and molten salt is filled between the outer insulation layer and the oxidation chamber; The third controller is used to control the auxiliary heating component to turn on when the concentration of gas after pretreatment is less than a preset concentration, thereby raising the temperature of the oxidation chamber to a preset temperature; wherein the auxiliary heating component adopts fuel-assisted heating or electric-assisted heating.

7. The skid-mounted low-concentration gas flameless oxidation power generation system according to claim 3, characterized in that, The heating surface of the waste heat boiler at the flue gas inlet section is made of bare tube, while the heating surface of the waste heat boiler at the flue gas outlet section is made of corrugated tube or finned tube.

8. The skid-mounted low-concentration gas flameless oxidation power generation system according to claim 2, characterized in that, When the number of gas treatment modules is less than or equal to 3, the power generation module adopts a power generation device based on Rankine cycle low-temperature waste heat power generation or a power generation device based on screw expander power generation; when the number of gas treatment modules is greater than or equal to 4, the power generation module adopts a power generation device based on steam turbine power generation.

9. The skid-mounted low-concentration gas flameless oxidation power generation system according to claim 1, characterized in that, The exhaust steam treatment module includes: a condensation unit and a water treatment unit; The condensation unit is used to condense the exhaust steam to obtain condensate. The water treatment unit is used to treat the condensate to obtain low-temperature water, and then transport the low-temperature water to the gas treatment module.

10. A skid-mounted low-concentration gas flameless oxidation power generation method, operating based on the skid-mounted low-concentration gas flameless oxidation power generation system according to any one of claims 1-9, characterized in that, include: The gas treatment module performs flameless oxidation on low-concentration gas to obtain high-temperature flue gas, and then exchanges heat between the high-temperature flue gas and low-temperature water to obtain low-temperature flue gas and saturated steam; the temperature of the high-temperature flue gas is higher than the temperature of the low-temperature water, and the temperature of the high-temperature flue gas is higher than the temperature of the low-temperature flue gas. The superheater heats the saturated steam to obtain superheated steam; The power generation module generates electricity based on the superheated steam, obtaining exhaust steam and electrical energy; The flue gas purification module purifies the low-temperature flue gas to obtain exhaust-ready flue gas. The exhaust steam treatment module processes the exhaust steam to obtain low-temperature water, and then transports the low-temperature water to the gas treatment module.

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