Underground coal gasification synthesis gas purification device

Abstract

The invention discloses an underground coal gasification synthesis gas purification device which comprises a pretreatment unit, and the pretreatment unit comprises a cyclone separator and a bag-type dust collector and is used for removing solid particles in synthesis gas; the desulfurization unit is used for treating sulfides in a combined manner of alkaline solution absorption and zinc oxide desulfurizer removal; the decarbonization unit is used for separating carbon dioxide by adopting pressure swing adsorption; the deoxidation unit is used for removing oxygen through catalytic combustion reaction under the action of a catalyst; a fine purification unit; the fine purification unit comprises a molecular sieve, and the molecular sieve is used for adsorbing impurities. Through cooperative work of the pretreatment unit, the desulfurization unit, the decarbonization unit, the deoxidation unit and the fine purification unit, various impurities in the synthesis gas can be comprehensively and efficiently removed, the quality of the synthesis gas is remarkably improved, and strict requirements of different chemical production on raw material gas are met.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of energy chemical equipment, and particularly relates to an underground coal gasification synthesis gas purification device. BACKGROUND

[0002] Underground coal gasification technology is an advanced technology for directly converting underground coal into combustible gas, and has broad application prospects in the energy field. However, the synthesis gas generated by underground coal gasification contains solid particles, sulfides, carbon dioxide, oxygen and trace impurities and the like. The presence of these impurities seriously affects the quality of the synthesis gas and subsequent application:

[0003] Solid particles can wear out subsequent equipment, reduce the service life of the equipment and increase the equipment maintenance cost;

[0004] Sulfides not only cause corrosion to the equipment, but also affect the activity of the catalyst in the chemical production process and reduce the product quality;

[0005] Carbon dioxide reduces the calorific value of the synthesis gas and affects the use efficiency of the synthesis gas;

[0006] The presence of oxygen can cause safety hazards in subsequent chemical reactions, and trace impurities can also interfere with the chemical properties of the synthesis gas.

[0007] At present, the existing synthesis gas purification device has the following problems: the purification process is single, and it is difficult to effectively remove multiple impurities at the same time; the efficiency of part of the purification methods is low, and it is difficult to meet the production demand of high-quality synthesis gas; the degree of automation of the device is low, and the operating parameters are difficult to accurately control, resulting in unstable purification effect. Therefore, it is urgent to develop an efficient, stable and highly automated underground coal gasification synthesis gas purification device. SUMMARY

[0008] Therefore, the technical problem to be solved by the present application is unstable purification effect.

[0009] The above technical problems are solved by the following technical solutions: the present application provides an underground coal gasification synthesis gas purification device, which comprises a pretreatment unit, the pretreatment unit comprises a cyclone separator and a bag-type dust collector to remove solid particles in the synthesis gas;

[0010] A desulfurization unit, the desulfurization unit removes sulfides by a combination of alkali solution absorption and zinc oxide desulfurization agent;

[0011] A decarbonization unit, the decarbonization unit separates carbon dioxide by pressure swing adsorption;

[0012] A deoxygenation unit, the deoxygenation unit removes oxygen by catalytic combustion reaction under the action of a catalyst;

[0013] The fine purification unit comprises a molecular sieve for adsorbing impurities.

[0014] In a preferred embodiment of the underground coal gasification synthetic gas purification device, the separation efficiency of the cyclone separator in the pretreatment unit is not less than 85%, and the filtering accuracy of the bag-type dust collector is 0.1 μm.

[0015] In a preferred embodiment of the underground coal gasification synthetic gas purification device, the alkaline solution in the desulfurization unit is one of a sodium carbonate solution and a sodium hydroxide solution, the hydrogen sulfide content in the synthetic gas after wet desulfurization is less than or equal to 50 ppm, and the hydrogen sulfide content after dry desulfurization is less than or equal to 1 ppm.

[0016] In a preferred embodiment of the underground coal gasification synthetic gas purification device, the adsorption pressure range of the pressure swing adsorption technology in the decarburization unit is 1.5-3 MPa, and the desorption pressure range is 0.1-0.3 MPa.

[0017] In a preferred embodiment of the underground coal gasification synthetic gas purification device, the catalyst in the deoxidization unit is one of a platinum-based catalyst and a palladium-based catalyst, and the temperature of the catalytic combustion reaction is controlled in the range of 200-400 ℃.

[0018] In a preferred embodiment of the underground coal gasification synthetic gas purification device, the molecular sieve in the fine purification unit is used for adsorbing water and carbon dioxide in the synthetic gas.

[0019] In a preferred embodiment of the underground coal gasification synthetic gas purification device, a gas buffer tank is arranged downstream of the pretreatment unit, and the buffer tank is used for stabilizing the synthetic gas flow and providing a stable gas source for the subsequent purification units.

[0020] In a preferred embodiment of the underground coal gasification synthetic gas purification device, a gas cooler is arranged between the desulfurization unit and the decarburization unit, between the decarburization unit and the deoxidization unit, and between the deoxidization unit and the fine purification unit, and is used for adjusting the temperature of the synthetic gas to a working temperature suitable for the corresponding unit.

[0021] In a preferred embodiment of the underground coal gasification synthetic gas purification device, a control system is further included, and the control system can monitor the operating parameters of each unit and automatically adjust the operating state of each unit device according to preset values.

[0022] In a preferred embodiment of the underground coal gasification synthetic gas purification device, the operating parameters include gas flow, pressure, temperature and impurity content, and the control system adopts a monitoring module composed of a PLC controller and an upper computer.

[0023] The present application has the beneficial effect that through the synergistic work of the pretreatment unit, desulfurization unit, decarburization unit, deoxidation unit and fine purification unit, various impurities in the synthesis gas can be comprehensively and efficiently removed, the quality of the synthesis gas is significantly improved, and the strict requirements of different chemical production on raw gas are met. BRIEF DESCRIPTION OF DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below only relate to some embodiments of the present application, but not limit the present application. Among them:

[0025] Figure 1 The constructional drawing of the underground coal gasification synthesis gas purification device is shown; DETAILED DESCRIPTION

[0026] In order to make the skilled in the art better understand the present application, the present application will be further described in detail below in combination with specific embodiments and drawings.

[0027] The terms used in the present application are those general terms currently widely used in the art in consideration of the functions about the present application, but these terms can be changed according to the intention of the person skilled in the art, precedents or new technologies in the art. In addition, specific terms can be selected by the applicant, and in this case, the detailed meaning thereof will be described in the detailed description of the present application. Therefore, the terms used in the specification should not be understood as mere names, but based on the meaning of the terms and the overall description of the present application.

[0028] REFERENCE Figure 1 The present embodiment provides an underground coal gasification synthesis gas purification device, which comprises a pretreatment unit 100, a desulfurization unit 200, a decarburization unit 300, a deoxidation unit 400 and a fine purification unit 500 connected in sequence along the synthesis gas treatment process and working synergistically;

[0029] The pretreatment unit 100 comprises a cyclone separator 101 and a bag filter 102 connected in sequence, wherein the cyclone separator 101 separates the solid particles in the synthesis gas from the gas by centrifugal force to preliminarily remove the solid particles with larger particle size, and the bag filter 102 further filters the synthesis gas treated by the cyclone separator 101 by the filter medium to trap the solid particles with small particle size, and the two work synergistically to remove the solid particles in the synthesis gas to avoid abrasion of the subsequent equipment caused by solid impurities;

[0030] The desulfurization unit 200 includes a wet desulfurization assembly and a dry desulfurization assembly. The wet desulfurization assembly chemically reacts with hydrogen sulfide in the synthesis gas by using an alkaline solution to absorb and preliminarily remove sulfides. The dry desulfurization assembly chemically adsorbs residual sulfides by using a zinc oxide desulfurizer to deeply remove sulfides. The two assemblies work together to reduce the content of sulfides in the synthesis gas, prevent corrosion of equipment by sulfides, and affect the activity of catalysts in subsequent production.

[0031] The decarbonization unit 300 uses a pressure swing adsorption assembly. The adsorbent selectively adsorbs carbon dioxide in the synthesis gas under specific pressure conditions, and then desorbs the adsorbed carbon dioxide by changing the pressure, so as to separate carbon dioxide from other components in the synthesis gas and improve the heat value of the synthesis gas.

[0032] The deoxidization unit 400 includes a catalytic reaction chamber. Under the action of the catalyst in the catalytic reaction chamber, oxygen in the synthesis gas reacts with hydrogen or carbon monoxide to generate water or carbon dioxide, so as to remove oxygen in the synthesis gas and eliminate safety hazards in subsequent chemical production.

[0033] The fine purification unit 500 includes a molecular sieve. The molecular sieve adsorbs trace impurities in the synthesis gas by molecular sieve separation and adsorption, so as to further improve the purity of the synthesis gas and meet the needs of subsequent high-quality chemical production.

[0034] As an optional embodiment, the cyclone separator 101 operates based on the principle of centrifugal force. When the synthesis gas enters the inside of the cyclone separator 101 from the inlet, it forms a high-speed rotating gas flow along a specific path. During the rotation process, the solid particles in the synthesis gas are significantly larger in density than the gas molecules, and thus are subjected to a centrifugal force significantly greater than that of the gas molecules, so as to be thrown to the inner wall of the separator. These solid particles separated to the inner wall gradually settle to the bottom of the separator under the joint action of gravity and the pushing force of the gas flow, and are finally collected and discharged through the ash discharge structure, while the preliminarily purified gas flows upward along the central channel to complete the preliminary separation process. The separation efficiency of the cyclone separator 101 for solid particles is not less than 85%, which can effectively remove relatively large solid impurities in the synthesis gas and greatly reduce the processing load of subsequent filtration equipment.

[0035] The bag filter 102 is arranged behind the cyclone separator 101, and is used for deep filtration of the preliminarily separated synthesis gas. The core filtering component of the bag filter is a filter bag, and the filtering medium on the surface of the filter bag has a precise pore structure. When the synthesis gas flows through the filter bag, the gas can smoothly pass through the pores of the filtering medium, while the residual small solid particles are trapped on the surface or in the pores of the filtering medium, thereby achieving efficient capture of the small particles. The filtering precision of the bag filter 102 reaches 0.1 μm, and even solid particles with extremely small particle sizes can be effectively intercepted, so as to ensure that the content of solid particles in the synthesis gas processed by the pretreatment unit 100 is greatly reduced.

[0036] As an optional embodiment, the desulfurization unit 200 is a core link for removing sulfides in the synthesis gas. Through the progressive process of wet desulfurization and dry desulfurization, efficient and deep removal of sulfides is achieved, thereby avoiding the corrosion of sulfides on the subsequent equipment and the adverse effects of sulfides on the activity of catalysts in chemical production.

[0037] In the wet desulfurization stage, sodium carbonate solution or sodium hydroxide solution is selected as the alkaline absorbent. Both of the two solutions have suitable alkalinity, and can fully neutralize hydrogen sulfide in the synthesis gas. When the synthesis gas enters the wet desulfurization assembly, it will form sufficient gas-liquid contact with the sprayed or flowing alkaline solution. As an acidic gas, hydrogen sulfide will react with active components such as sodium ions and hydroxide ions in the solution to form sulfide salts that are soluble in water. These soluble salts enter the subsequent separation system with the solution and are concentrated for treatment, thereby removing most of the hydrogen sulfide in the synthesis gas, reducing the hydrogen sulfide content to below 50 ppm after wet desulfurization. This process quickly reduces the concentration of sulfides by means of efficient mass transfer between the gas and liquid phases.

[0038] The dry desulfurization stage is arranged immediately after the wet desulfurization stage. The zinc oxide desulfurizer filled in the dry desulfurization stage has strong chemical adsorption and reaction activity. After the wet desulfurization, the residual trace amount of hydrogen sulfide in the synthesis gas enters the dry desulfurization assembly, and reacts with the zinc oxide desulfurizer to generate chemically stable zinc sulfide solid. Since the zinc sulfide is insoluble in gas and is not easy to decompose, it is firmly fixed inside the desulfurizer, thereby achieving deep removal of residual sulfides and reducing the hydrogen sulfide content in the final synthesis gas to below 1 ppm.

[0039] As an optional embodiment, the adsorption pressure range of the pressure swing adsorption technology in the decarburization unit 300 is 1.5-3 MPa, and the desorption pressure range is 0.1-0.3 MPa. The decarburization unit 300 is a link for separating carbon dioxide in the synthesis gas and improving the heat value of the synthesis gas. The core technology is the pressure swing adsorption technology, which realizes efficient separation of carbon dioxide and other effective components in the synthesis gas by regulating the system pressure and using the selective adsorption characteristics of the adsorbent for carbon dioxide.

[0040] In the adsorption stage, the system pressure is controlled in a certain range. Under this pressure condition, the adsorption capacity of the adsorbent for carbon dioxide is significantly enhanced, when the synthesis gas flows through the adsorption area of the decarbonization unit 300, the carbon dioxide molecules are preferentially captured and firmly adsorbed by the active sites on the surface of the adsorbent, and other combustible components in the synthesis gas can pass through the adsorption area smoothly because of the weak affinity with the adsorbent, thereby realizing the preliminary separation of carbon dioxide. The adsorption pressure range is 1.5-3 MPa. The selection of this pressure range can not only ensure the desorption of carbon dioxide to restore the adsorption capacity of the adsorbent for recycling, but also maximize the loss of effective components in the synthesis gas.

[0041] When the adsorbent reaches adsorption saturation, the system enters the desorption stage, at which time the pressure is adjusted to another certain range. Under this pressure condition, the interaction between the adsorbent and carbon dioxide is weakened, and the adsorbed carbon dioxide molecules are desorbed from the surface of the adsorbent into the desorption gas stream and are collected and treated. The desorption pressure range is 0.1-0.3 MPa. The selection of this pressure range can not only ensure the desorption of carbon dioxide to restore the adsorption capacity of the adsorbent for recycling, but also maximize the loss of effective components in the synthesis gas.

[0042] As an optional embodiment, the deoxygenation unit 400 is a key link for eliminating potential safety risks of oxygen in the synthesis gas purification process, and realizes efficient removal of oxygen through catalytic combustion reaction, thereby providing guarantee for safe and stable operation of subsequent chemical production.

[0043] The unit uses platinum-based catalyst or palladium-based catalyst as the core catalytic component of the reaction. Platinum-based catalyst and palladium-based catalyst can significantly reduce the activation energy of the oxidation reaction of oxygen and the reducing components hydrogen and carbon monoxide in synthesis gas due to their excellent catalytic activity and selectivity, thereby ensuring efficient reaction under controllable conditions. The surface of such noble metal catalysts has abundant active sites that can specifically adsorb oxygen molecules and hydrogen, carbon monoxide and other reducing gas molecules, thereby accelerating the oxidation reaction by optimizing the reaction path. Even in the case of low oxygen concentration in synthesis gas, sufficient conversion of oxygen can still be achieved.

[0044] The temperature of the catalytic combustion reaction is strictly controlled in the range of 200-400℃. This temperature interval is set based on the comprehensive consideration of reaction characteristics and catalyst performance: when the temperature is lower than 200℃, the catalyst activity is difficult to fully exert, the reaction rate of oxygen and reducing gas is slow, and the oxygen in the synthesis gas cannot be completely removed, which may cause residual oxygen to enter the subsequent process; when the temperature is higher than 400℃, not only the platinum-based or palladium-based catalyst may be deactivated due to thermal sintering, shortening its service life, but also the over-oxidation of effective components in the synthesis gas or other unintended side reactions may occur, causing the loss of raw gas. Within the 200-400℃ interval, the catalyst can maintain the best active state, promoting the reaction of oxygen and hydrogen to generate water and the reaction of oxygen and carbon monoxide to generate carbon dioxide, both of which are harmless substances and will not adversely affect the subsequent production, thereby achieving efficient and complete removal of oxygen.

[0045] As an optional embodiment, the fine purification unit 500 is the terminal processing link of the synthesis gas purification process, and through the adsorption of the molecular sieve, it deeply removes the trace amount of water and carbon dioxide remaining after the pretreatment, desulfurization, decarburization, and deoxidation units, and further improves the purity of the synthesis gas.

[0046] As an optional embodiment, the device further includes a gas buffer tank 800, which is arranged downstream of the pretreatment unit 100, connected to the outlet of the pretreatment unit 100 at one end, and connected to the inlet of the desulfurization unit 200 at the other end, serving as a key connecting component between the pretreatment unit 100 and the subsequent purification units.

[0047] The gas buffer tank 800 forms a closed space with a certain volume inside, which can accommodate the synthesis gas after the removal of solid particulate matter by the pretreatment unit 100. Since the flow of synthesis gas generated by underground coal gasification may be unstable due to fluctuations in gas production conditions when entering the purification system, such fluctuations may interfere with the gas-liquid contact, adsorption reaction, and other processes in the subsequent desulfurization, decarburization, and other units, for example, the contact efficiency of the alkaline solution with the synthesis gas in the desulfurization unit 200 is reduced, or the pressure stability of the pressure swing adsorption in the decarburization unit 300 is affected, thereby reducing the purification effect.

[0048] As an optional embodiment, in the purification process of synthesis gas, the desulfurization unit 200, the decarburization unit 300, the deoxidation unit 400, and the fine purification unit 500 all have specific requirements for the inlet gas temperature, and too high or too low temperature will affect the purification efficiency and stability of each unit. Therefore, the device is provided with a gas cooler 700 between the desulfurization unit 200 and the decarburization unit 300, between the decarburization unit 300 and the deoxidation unit 400, and between the deoxidation unit 400 and the fine purification unit 500, as a key equipment for temperature regulation between each unit.

[0049] The gas cooler 700 precisely regulates the temperature of the synthesis gas by heat exchange principle. When the synthesis gas flows out of the upstream unit, the temperature may deviate from the suitable working range of the downstream unit due to chemical reactions within the unit or factors such as gas flow compression. At this time, the synthesis gas flows through the gas cooler 700, and the temperature is adjusted to the optimal interval required by the downstream unit through heat exchange with the cooling medium.

[0050] As an optional embodiment, the device further comprises a control system 600 capable of monitoring the operating parameters of each unit and automatically adjusting the operating state of each unit equipment according to the preset value. The control system 600 collects the key operating parameters of the synthesis gas at each link in real time through various types of sensing components distributed on the pretreatment unit 100, desulfurization unit 200, decarburization unit 300, deoxidation unit 400, fine purification unit 500 and auxiliary equipment. These parameters include the flow, pressure and temperature of the synthesis gas, as well as the impurity content at the outlet of each unit.

[0051] As an optional embodiment, the operating parameters monitored by the control system 600 specifically include the gas flow, pressure and temperature of the synthesis gas in each purification unit, as well as the impurity content in the synthesis gas after being treated by each unit. These parameters reflect the operating state and purification effect of each unit.

[0052] The control system 600 adopts a monitoring module composed of a PLC controller 601 and an upper computer 602. Among them, the PLC controller 601 serves as the control core, responsible for receiving real-time parameter signals collected by various sensors, performing operation processing according to the preset control logic and process threshold, and sending adjustment instructions to the execution equipment of each unit to realize automatic control of the equipment operating state.

[0053] Finally, it should be pointed out that the above detailed description of the method and device is only an embodiment, and those skilled in the art can modify the embodiment in different ways without departing from the scope of the present application.

Claims

1. An underground coal gasification syngas purification device, characterized in that: include, The pretreatment unit (100) includes a cyclone separator (101) and a bag filter (102) which can remove solid particulate matter from the syngas. A desulfurization unit (200) treats sulfides by a combination of alkaline solution absorption and zinc oxide desulfurizing agent removal; A decarbonization unit (300) employs pressure swing adsorption to separate carbon dioxide; A deoxygenation unit (400) removes oxygen through a catalytic combustion reaction under the action of a catalyst; Fine purification unit (500); the fine purification unit (500) includes a molecular sieve for adsorbing impurities.

2. The underground coal gasification syngas purification device according to claim 1, characterized in that: In the pretreatment unit (100), the separation efficiency of the cyclone separator (101) is not less than 85%, and the filtration accuracy of the bag filter (102) is 0.1μm.

3. The underground coal gasification syngas purification device according to claim 1, characterized in that: In the desulfurization unit (200), the alkaline solution is either sodium carbonate solution or sodium hydroxide solution. After wet desulfurization, the hydrogen sulfide content in the synthesis gas is ≤50ppm, and after dry desulfurization, the hydrogen sulfide content is ≤1ppm.

4. The underground coal gasification syngas purification device according to claim 1, characterized in that: The adsorption pressure range of the pressure swing adsorption technology in the decarbonization unit (300) is 1.5-3 MPa, and the desorption pressure range is 0.1-0.3 MPa.

5. The underground coal gasification syngas purification device according to claim 1, characterized in that: In the deoxygenation unit (400), the catalyst is either a platinum-based catalyst or a palladium-based catalyst, and the temperature of the catalytic combustion reaction is controlled at 200-400℃.

6. The underground coal gasification syngas purification device according to claim 1, characterized in that: In the fine purification unit (500), molecular sieves are used to adsorb water and carbon dioxide from the syngas.

7. The underground coal gasification syngas purification device according to claim 1, characterized in that: It also includes a gas buffer tank (800) located downstream of the pretreatment unit (100), the buffer tank (800) being used to stabilize the syngas flow rate and provide a stable gas source for the subsequent purification unit.

8. The underground coal gasification syngas purification device according to claim 1, characterized in that: Gas coolers (700) are provided between the desulfurization unit (200) and the decarbonization unit (300), between the decarbonization unit (300) and the deoxygenation unit (400), and between the deoxygenation unit (400) and the fine purification unit (500) to adjust the temperature of the syngas to a working temperature suitable for the corresponding unit.

9. The underground coal gasification syngas purification device according to claim 1, characterized in that: It also includes a control system (600), which can monitor the operating parameters of each unit and automatically adjust the operating status of each unit device according to preset values.

10. The underground coal gasification syngas purification device according to claim 9, characterized in that: The operating parameters include gas flow rate, pressure, temperature and impurity content. The control system (600) adopts a monitoring module consisting of a PLC controller (601) and a host computer (602).

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