Method and device for removing impurities in mixed gas

Abstract

The invention provides a method and a device for removing impurities in mixed gas. The invention relates to the field of mixed gas purification. The method comprises the following steps: introducing mixed coal gas into a remover solution to contact with cleaning foam formed under the action of the remover solution so as to wash the mixed coal gas to obtain primarily washed mixed coal gas; and carrying out heat exchange on the primarily washed mixed gas under the condition that the primarily washed mixed gas is not in direct contact with the refrigerant medium, so that the temperature difference of the temperature reduction of the primarily washed mixed gas is more than 3 DEG C to obtain condensed mixed liquid and rewashed mixed gas. And dehydrating the re-washed mixed gas to obtain clean mixed gas. The water separated by the method is large in specific surface area and high in adsorption and combination capacity, and is combined with the emulsion component of the residual remover and mixed with substances in the coal gas to form a condensed mixed solution. The method for removing the impurities in the mixed coal gas is simple, few impurities exist in the clean mixed coal gas, the water content is low, and the probability that coal gas facilities are blocked can be further reduced.

Description

Technical Field

[0001] The invention relates to the field of mixed coal gas purification, and in particular to a method for removing impurities in mixed coal gas and an impurity removal device. Background Art

[0002] When blast furnace gas is produced, it contains impurities such as gasified substances and solid dust. After dry dust removal, the dust content is effectively controlled, generally reaching 10-20 mg / m 3 However, salt substances such as chlorides in coal gas cannot be removed.

[0003] Coke oven gas undergoes a series of wet and dry purification processes, but still contains impurities such as tar, dust, naphthalene, ammonia, hydrogen sulfide, benzene, hydrogen cyanide, sulfur dioxide, nitrogen oxides, etc. Therefore, when the two gases are mixed, a mixed gas with very complex impurities is formed, causing frequent blockages in gas facilities.

[0004] In some existing mixed gas impurity removal methods, the mixed gas is passed through a cleaning agent for cleaning, then washed with water, and then dehydrated to obtain a clean mixed gas. However, in subsequent operation, the clean mixed gas produced in this way has not significantly improved the problem of gas facility blockage. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for removing impurities from mixed coal gas and an impurity removal device to solve the technical problem that the blockage problem of coal gas facilities has not been significantly improved.

[0006] To achieve the above object, the present invention provides a method for removing impurities in mixed coal gas, comprising the following steps:

[0007] The mixed coal gas is passed into the remover solution and contacted with the cleaning foam formed by the remover solution, thereby washing to obtain the primary washed mixed coal gas. The solvent of the remover solution is water.

[0008] The primary washed mixed coal gas is subjected to heat exchange without direct contact with a refrigerant medium so that the temperature of the primary washed mixed coal gas decreases by a temperature difference of more than 3° C., thereby obtaining a condensed mixed liquid and a secondary washed mixed coal gas.

[0009] The rewashed mixed coal gas is dehydrated to obtain a clean mixed coal gas.

[0010] According to an embodiment of the present application, the temperature of the primary-wash mixed coal gas is 30°C-35°C, and the temperature of the secondary-wash mixed coal gas is 27°C-32°C.

[0011] According to an embodiment of the present application, the heat exchange of the pre-washed mixed coal gas causes the temperature of the pre-washed mixed coal gas to drop by a temperature difference of 3°C-8°C.

[0012] According to an embodiment of the present application, the pre-washed mixed coal gas is heat exchanged under the condition of being thermally isolated from the outside.

[0013] The rewashed mixed coal gas is dehydrated under heat-insulated conditions from the outside.

[0014] According to an embodiment of the present application, the cold medium is chilled water, and the temperature of the chilled water is 8-10°C.

[0015] The present application also provides a device for removing impurities from mixed coal gas, comprising:

[0016] The first washing chamber contains a remover solution at the bottom. The first washing chamber has an air inlet pipe, a remover solution circulation pipeline, a spray head and a discharge pipeline. The end of the air inlet pipe is immersed in a solution area formed by the remover solution. The spray head and the discharge pipeline are both located above the solution area. The remover solution circulation pipeline is connected between the spray head and the solution area.

[0017] The second washing chamber is connected to the discharge pipeline of the first washing chamber, and a heat exchange mechanism is provided in the second washing chamber. The heat exchange mechanism has a refrigerant medium, which is used to condense the primary washing mixed coal gas discharged from the discharge pipeline so that the temperature difference of the primary washing mixed coal gas drops by more than 3°C, and obtain a condensed mixed liquid and a secondary washing mixed coal gas.

[0018] The dehydration chamber is communicated with the second washing chamber, and the dehydration chamber has a dehydration mechanism for dehydrating the re-washed mixed coal gas.

[0019] According to an embodiment of the present application, the heat exchange mechanism includes a coil, the cold medium in the coil is chilled water, and the temperature of the chilled water is 8-10°C.

[0020] According to an embodiment of the present application, the second washing chamber has a heat insulation layer.

[0021] The dehydration chamber is provided with a heat insulation layer.

[0022] According to an embodiment of the present application, the bottom of the second washing chamber further has a mixed liquid discharge pipe for discharging the condensed mixed liquid.

[0023] According to an embodiment of the present application, a gas water seal mechanism is further included, and the mixed liquid discharge pipeline is connected to the gas water seal mechanism.

[0024] The above-mentioned method for removing impurities from the mixed coal gas is to wash the mixed coal gas in a remover solution to obtain a pre-washed mixed coal gas. During the condensation process of the pre-washed mixed coal gas, a large amount of water is precipitated because the water content of the saturated gas decreases as the temperature decreases. At the same time, the precipitated water will combine with the residual remover components and the substances in the mixed coal gas to form a condensed mixed liquid due to its large specific surface area and strong adsorption and binding ability. This process is equivalent to a second-stage washing of the pre-washed mixed coal gas to obtain a re-washed mixed coal gas. The re-washed mixed coal gas is further dehydrated to obtain a clean mixed coal gas. The above-mentioned method for removing impurities from the mixed coal gas is simple, the clean mixed coal gas has fewer impurities and a high degree of cleanliness, and can further reduce the probability of blockage of gas facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0026] Figure 1 It is a schematic structural diagram of a device for removing impurities from mixed coal gas according to one embodiment of the present application.

[0027] The realization of the purpose, functional features and advantages of the present invention will be further explained in conjunction with the implementation methods and with reference to the accompanying drawings.

[0028] 100, first washing chamber; 200, second washing chamber; 300, dehydration chamber; 400, heat exchange mechanism; 500, gas water seal mechanism; 140, discharge pipeline; 210, mixed liquid discharge pipeline. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be noted that all directional indications (such as up, down, etc.) in the embodiments of the present invention are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0031] In addition, in the present invention, the descriptions such as "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features.

[0032] Furthermore, the technical solutions between the various embodiments of the present invention may be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in the field. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0033] To achieve the above object, the present invention provides a method for removing impurities in mixed coal gas, comprising the following steps:

[0034] S100: The mixed coal gas is passed into the remover solution and contacted with the cleaning foam formed by the remover solution, thereby washing and obtaining the primary washing mixed coal gas.

[0035] See also Figure 1 This step is performed in a relatively closed environment, such as a relatively closed container, which may be a washing tower, or a separate closed space of a washing tower, such as the first washing chamber 100 .

[0036] The remover solution is contained in a closed environment. The mixed coal gas is passed into the remover solution, such as by inserting the air inlet pipe 110 into the remover solution, thereby passing into the remover solution. Because the remover solution is easy to generate cleaning foam. The remover solution can generate cleaning foam in many ways.

[0037] Exemplarily, the remover solution is stirred, such as adding a stirring mechanism in a closed environment, so that it forms cleaning foam. Exemplarily, the remover solution is blown to form cleaning foam. Another exemplary method is to spray the remover solution, such as extracting part of the remover solution through a pipeline and spraying it from top to bottom to form cleaning foam.

[0038] The cleaning foam may be located in the remover solution or outside the remover solution, such as partially filling or completely filling the closed environment. The mixed gas flows upward, escapes from the remover solution and contacts the cleaning foam of the remover solution, or in other words, contacts the cleaning foam in the remover solution.

[0039] In some embodiments, the solvent of the remover solution is water. In terms of mass percentage, the remover solution includes: 4%-7% sodium bicarbonate, 18%-22% sodium metasilicate, 1%-5% sodium dodecyl sulfate and 0.5%-2% dodecylphenol polyoxyethylene ether.

[0040] In this step, the above substances are dissolved in water to obtain a remover solution. Sodium metasilicate has strong emulsifying ability, good surface activity and certain saponification ability, and has a good grease removal effect. When used in combination with other surfactants, it becomes an excellent wetting agent among alkaline compounds. It has a large viscosity. Sodium metasilicate is hydrolyzed in water to generate silicic acid, which is suspended in the liquid in a micellar structure and has strong adsorption. In order to improve the cleaning ability, it is often used in conjunction with other surfactants to improve the cleaning effect. This solvated micelle can suspend and disperse solid dirt particles in the gas and emulsify oil in the gas. Usually, the amount of sodium metasilicate in the industrial remover solution is relatively high, and the general addition amount is 18% to 22%, but excessive addition will have an impact on the environment. The applicable concentration in this case is about 20%.

[0041] Sodium metasilicate and sodium carbonate are not miscible. Sodium carbonate is highly alkaline and can easily cause sodium metasilicate to precipitate. Therefore, sodium carbonate cannot be used. In addition, sodium bicarbonate reacts more strongly with the acidic substances in the mixed gas than sodium carbonate, which will accelerate the removal of the acidic substances in the gas. Sodium bicarbonate is a washing component and has a good effect in washing gas. Since the acidic substances in the mixed gas are generally mg / m 3 The CO2 generated by the reaction with the acidic substances in the mixed gas has no effect on the percentage concentration level of the main components of the mixed gas, and will not affect the calorific value. Sodium bicarbonate is weakly alkaline and will not form precipitation with sodium metasilicate. The concentration of sodium bicarbonate selected in this case is 6% (because the solubility of sodium bicarbonate in 0℃ water is 7%).

[0042] Sodium dodecyl sulfate, also known as K12, is a very common anionic surfactant with excellent detergency, rich cleaning foam, emulsification, wettability, good biodegradability, and easy biochemical treatment in wastewater treatment. The usual applicable concentration is 1%-5%. In this case, the concentration of sodium dodecyl sulfate is 5% to enhance the cleaning foam and detergency.

[0043] Dodecylphenol polyoxyethylene ether, also known as OP-10, is a very common nonionic surfactant with excellent emulsification, washing, dispersing, penetrating and wetting effects. The molecule has two groups, hydrophilic and lipophilic. It has a good solubilizing effect on non-polar compounds in coal gas and organic compounds containing polar groups. It is acid-resistant, alkali-resistant and hard water-resistant. OP-10 has good biodegradability. Usually anionic surfactants are used in combination with nonionic surfactants to improve their efficacy. OP-10 is usually used in a concentration of 0.5%-2%. In this case, the concentration of OP-10 is 2% to enhance the emulsification and decontamination capabilities.

[0044] The impurity remover solution in the mixed coal gas includes a strong decontamination ability and a highly surface active substance, and is easy to generate rich foam. The cleaning foam increases the contact time between the mixed coal gas and the remover solution, thereby enhancing the removal effect of impurities and simplifying the difficulty of subsequent removal work such as water washing or (and) condensation water washing.

[0045] The cleaning foam increases the contact time between the mixed coal gas and the remover solution. During the contact process, the cleaning foam reacts with the mixed coal gas, which is called washing. This washing is the first-level washing. The remover solution washing removes salts, tar, dust, naphthalene, ammonia, hydrogen sulfide, benzene, hydrogen cyanide, sulfur dioxide, and nitrogen oxides in the mixed coal gas to obtain the primary washed mixed coal gas.

[0046] The more specific principle is as follows: the remover solution itself is liquid, and during use, it comes into contact with coal gas to react or wash impurities in the coal gas. Due to the action of the surfactant sodium metasilicate in the remover solution and the solid dust in the mixed coal gas, the dust suspends and disperses the solid dirt particles in the foam, and the solid dust in the mixed coal gas is removed and enters the remover solution, and enters the wastewater by replacing the remover solution. In addition, the organic matter in the mixed coal gas, including tar substances, tea, benzene, etc., reacts with the surfactant of the remover solution. The surfactant molecules have hydrophilic groups and lipophilic groups, so the oil-in-water and water-in-oil forms are formed in the remover solution, and also enter the wastewater by replacing the remover solution. In addition, the sodium bicarbonate and sodium metasilicate in the remover solution are alkaline. Sodium bicarbonate is a washing component. It fully contacts and reacts with the acidic substances in the mixed gas, such as hydrogen sulfide, hydrogen cyanide, sulfur dioxide, nitrogen oxides, etc., as well as salts and ammonia substances under the action of the cleaning foam. In addition, sodium metasilicate is hydrolyzed in water to generate silicic acid suspended in the liquid in a micelle structure, which has strong adsorption, so the effect of washing the gas is good. Therefore, it also has a good desulfurization and denitrification effect.

[0047] S200: subjecting the primary washed mixed coal gas to heat exchange without direct contact with a refrigerant medium so that the temperature of the primary washed mixed coal gas decreases by a temperature difference of more than 3° C., thereby obtaining a condensed mixed liquid and a secondary washed mixed coal gas.

[0048] In this step, the initially washed mixed coal gas is discharged, such as through the exhaust pipe 140 of the first washing chamber 100, to another relatively closed environment, which can also be a relatively closed container, specifically a washing tower, or a separate enclosed space of the washing tower, such as the second washing chamber 200.

[0049] The pre-washed mixed coal gas is heat exchanged without direct contact with the refrigerant, such as the refrigerant in the heat exchange mechanism 400. The pre-washed mixed coal gas passes through the heat exchange mechanism 400 and is heat exchanged across the heat exchange mechanism 400. The refrigerant includes various types, such as water, air, cooling oil, etc., which are not specifically limited.

[0050] The temperature of the refrigerant medium is lower than the temperature of the primary wash mixed gas, and thus the temperature of the primary wash mixed gas decreases during the heat exchange process.

[0051] The primary washed mixed coal gas is a gas saturated with water. On the one hand, the mixed coal gas itself inevitably contains water, which is basically saturated with water. On the other hand, during the washing process with the remover solution, the primary washed mixed coal gas will also carry some water. Therefore, the water in the primary washed mixed coal gas is saturated.

[0052] When the temperature of the primary wash mixed coal gas decreases, the saturated gas water content of the primary wash mixed coal gas will decrease accordingly. At this time, the water in the primary wash mixed coal gas is in an oversaturated state, and water will precipitate out of it.

[0053] Part of the precipitated water is saturated water, which is supersaturated water that precipitates when the temperature cools down. The amount of this water can be calculated by looking up the table; the other part is the water entrained in the mixed gas after the initial washing, which will also precipitate after cooling.

[0054] Therefore, when the temperature of the primary washed mixed coal gas drops by more than 3°C, such as 3°C, 5°C, 7°C or 10°C or more, relatively more water will be precipitated.

[0055] For example, by using a refrigerant medium, such as chilled water (temperature 8-10°C) delivered from a refrigeration station to cool the gas, for example, from 35°C to 32°C, refer to Table 1, according to 1 standard atmospheric pressure 1.01*10 6 Pa (the relative pressure of gas transmission is 18KPa, i.e. 1.8*10 4 Pa, absolute pressure is 1.028*10 6 Pa, so we calculate it based on 1 standard atmospheric pressure), and the hourly gas flow rate is 10000m 3 / hourly calculation.

[0056] Table 1 Saturated gas water content at various temperatures under standard atmospheric pressure

[0057]

[0058] Calculation based on the analogy of gas to air: 6.014 grams of water will be released per kilogram of air, and the gas flow rate per hour is 10,000 m 3 / hour, 11210 kg mass at 1 standard atmospheric pressure, gas flow rate 10000m 3 67.4 kg / hour of water will be released per hour.

[0059] As the water is cooled and precipitated, when it first begins to precipitate, the water mist particles during condensation are small and have a large specific surface area. It has a strong adsorption capacity for the components in the coal gas, and will combine the remover solution emulsion components carried by the initial washing mixed coal gas and the residual impurities in the initial washing mixed coal gas (such as tar, salt substances, and some organic matter). Then the water mist particles quickly turn into water droplets and separate from the coal gas to form a condensed mixed liquid. The coal gas after the water droplets are separated is the re-washed mixed coal gas. This step is equivalent to a second-level washing of the initial washing mixed coal gas.

[0060] In this step, in addition to performing a second-stage washing on the primary washed mixed coal gas, thereby improving the cleanliness of the re-washed mixed coal gas, it also has the effect of reducing process costs.

[0061] Among them, the primary washed mixed gas is condensed to generate the secondary washed mixed gas, which is simple to operate and does not require additional water for washing, thus saving water resources and having low costs. Moreover, the condensed mixed liquid is produced by condensation, and its total amount as waste liquid is small, which is several times smaller than the waste liquid produced by washing with water. In this way, the wastewater treatment cost of the condensed mixed liquid is also greatly reduced, which is economical and environmentally friendly.

[0062] S300: Dehydrating the rewashed mixed coal gas to obtain a clean mixed coal gas.

[0063] In this step, the rewashed mixed gas is dehydrated, for example, by a folded plate dehydrator, to obtain a clean mixed gas, the water content of which is greatly reduced. The clean mixed gas can be used later, for example, by entering the radiant tube of the galvanizing line for combustion through a two-stage pressure regulation of the pipeline.

[0064] The above-mentioned method for removing impurities from the mixed coal gas is to wash the mixed coal gas with a remover solution to obtain a pre-washed mixed coal gas. During the condensation process of the pre-washed mixed coal gas, a large amount of water is precipitated because the water content of the saturated gas decreases as the temperature decreases. At the same time, the precipitated water will combine with the residual remover components (such as emulsion) and the substances in the mixed coal gas to form a condensed mixed liquid due to its large specific surface area and strong adsorption and binding ability. This process is equivalent to a second-stage washing of the pre-washed mixed coal gas to obtain a re-washed mixed coal gas. The re-washed mixed coal gas is further dehydrated to obtain a clean mixed coal gas. The above-mentioned method for removing impurities from the mixed coal gas is simple, the clean mixed coal gas has fewer impurities, high cleanliness, and reduced water content, which can further reduce the probability of blockage of gas facilities.

[0065] For example, after adopting the above-mentioned method for removing impurities from mixed gas, the filter screen of the nozzle of the gas facility is blocked once every two months instead of once every six months.

[0066] In some embodiments, the temperature of the primary-wash mixed coal gas is 30°C-35°C, and the temperature of the secondary-wash mixed coal gas is 27°C-32°C.

[0067] Under the above conditions, the clean mixed gas can have less impurities and higher cleanliness, which can further reduce the probability of blockage in gas facilities.

[0068] In some embodiments, the heat exchange of the pre-washed mixed coal gas causes the temperature of the pre-washed mixed coal gas to drop by a temperature difference of 3°C-8°C.

[0069] Under this condition, the impurity content in the clean mixed coal gas can be further reduced, the cleanliness can be improved, and the probability of blockage of the coal gas facilities can be reduced. The temperature difference range is appropriate. If the temperature difference range is too large, the cooling performance of the refrigerant medium is required to be high. If the temperature of the refrigerant medium is in a lower range, the cost will be higher. Or the initial washing mixed coal gas is required to stay for a long time during the heat exchange process, which reduces the production efficiency of the clean mixed coal gas.

[0070] In some embodiments, the pre-washed mixed coal gas is heat exchanged under heat-insulated conditions from the outside.

[0071] The rewashed mixed coal gas is dehydrated under heat-insulated conditions from the outside.

[0072] Under this condition, in step S200, the re-washed mixed coal gas is in a state of saturated gas water content after the temperature is lowered, wherein the water content is relatively low. In the dehydration step S300, since it is carried out under the condition of heat insulation from the outside. After the clean mixed coal gas leaves the equipment of this system, because there is no heat insulation effect, the temperature of the clean mixed coal gas therein will gradually increase due to the effect of the ambient temperature (such as the ambient temperature is high, greater than the temperature of the re-washed mixed coal gas).

[0073] The water content is low, so the water in the clean mixed gas is in an unsaturated dry state. Therefore, in the subsequent process of transporting the clean mixed gas to the gas-using equipment, it is not easy to condense water or the condensed water is less, which makes the combustion efficiency of the clean mixed gas high and reduces energy waste.

[0074] Moreover, the pipeline for conveying clean mixed gas is not easy to be corroded due to the precipitation of condensed water, which may cause the pipeline to be perforated and leak gas. It is also not easy for rust to form with the conveying of gas and cause the filter screen of the burner to be blocked.

[0075] Furthermore, it reduces the drainage load of the gas condensate drainers on the gas pipelines arranged along the way, improves the safety of gas facilities (gas condensate drainers sometimes carry gas when discharging condensate), and is more environmentally friendly (gas condensate drainers discharge a large amount of condensate, and treatment also requires costs).

[0076] In some embodiments, the cold medium is chilled water, and the temperature of the chilled water is 8-10° C. The chilled water comes from a refrigeration station, and the water temperature supplied from April to November is 8-10° C.

[0077] Chilled water is a product of the refrigeration station. Chilled water forms a closed loop with the second-stage washing in the refrigeration station to achieve an economical and efficient operation mode. The supply temperature of chilled water is 8-10℃, and the return temperature of chilled water is 10-12℃. The refrigeration station can cool the return water to 8-10℃ for water supply. During this period, there is no loss of chilled water. This is an energy-saving and environmentally friendly operation mode. In addition, the specific heat capacity of water is greater than that of gas. The use of chilled water can effectively reduce the temperature of the primary washing mixed gas.

[0078] The present application also provides a device for removing impurities from mixed coal gas, see Figure 1 ,include:

[0079] The first washing chamber 100 contains a remover solution at the bottom. The first washing chamber 100 has an air inlet pipe, a remover solution circulation pipeline, a spray head and a discharge pipeline 140. The end of the air inlet pipe is immersed in the solution area formed by the remover solution. The spray head and the discharge pipeline 140 are both located above the solution area. The remover solution circulation pipeline is connected between the spray head and the solution area.

[0080] The second washing chamber 200 is connected to the discharge pipeline 140 of the first washing chamber 100, and a heat exchange mechanism 400 is provided in the second washing chamber 200. The heat exchange mechanism 400 has a refrigerant medium therein, which is used to condense the primary washing mixed coal gas discharged from the discharge pipeline 140 so that the temperature difference of the primary washing mixed coal gas is reduced by more than 3°C, and obtain a condensed mixed liquid and a secondary washing mixed coal gas.

[0081] The dehydration chamber 300 is communicated with the second washing chamber 200, and the dehydration chamber 300 has a dehydration mechanism for dehydrating the re-washed mixed coal gas.

[0082] The above-mentioned device for removing impurities from mixed coal gas can implement the above-mentioned method for removing impurities from mixed coal gas, and therefore also has corresponding beneficial effects.

[0083] In some embodiments, a circulating pump is provided in the remover solution circulation pipeline, one end of which is located below the first washing chamber 100 to extract part of the remover solution therein, and the other end is connected to the shower head.

[0084] In some embodiments, see Figure 1 The impurity removal device is a tower structure, and the first washing chamber 100, the second washing chamber 200 and the dehydration chamber 300 are sequentially distributed from bottom to top. The design structure is compact and convenient for gas flow.

[0085] In some embodiments, the heat exchanger is arranged in parallel with more than 5 consecutive cooling stages. In this way, the cooling effect is enhanced; at the same time, the arrangement of more than 5 consecutive cooling stages in parallel slows down the gas flow rate, and the gas retention time is increased, which is beneficial to the gas condensation and subsequent dehydration.

[0086] In some embodiments, the heat exchange mechanism 400 includes a coil, the cold medium in the coil is chilled water, and the temperature of the chilled water is 8-10°C.

[0087] The coil has a long pipe and a thinner diameter, so the heat exchange efficiency is high. In addition, the thinner diameter makes it easier for water droplets to drip and separate from the gas.

[0088] In some embodiments, the second washing chamber 200 has a heat insulation layer. The dehydration chamber 300 is also provided with a heat insulation layer. This method has a simple structure and uses the ambient temperature to heat the clean mixed coal gas.

[0089] The water content is low, and the gas becomes unsaturated clean mixed gas. Therefore, in the subsequent process of transporting the clean mixed gas to the gas-using equipment, it is not easy to precipitate condensed water or the condensed water is less, so that the combustion efficiency of the clean mixed gas is high and energy waste is reduced during combustion.

[0090] In some embodiments, the bottom of the second washing chamber 200 further has a mixed liquid discharge pipe 210 for discharging the condensed mixed liquid.

[0091] The condensed mixed liquid is discharged into a pit for treatment. Referring to the above analysis, the total volume of the condensed mixed liquid is relatively small, which can reduce the treatment cost.

[0092] In some embodiments, a gas water seal mechanism 500 is further included, and the mixed liquid discharge pipeline 210 is in communication with the gas water seal mechanism 500 .

[0093] The gas water seal mechanism 500 is arranged on the mixed liquid discharge pipe 210, such as being arranged near a pit. The function of the gas water seal mechanism 500 is to seal and isolate the gas by using the liquid level of water to prevent the gas from leaking from the drainage.

[0094] The above technical solutions of the present invention are only preferred embodiments of the present invention, and the patent scope of the present invention is not limited thereto. All equivalent structural changes made by using the contents of the present invention specification and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A method for removing impurities from mixed coal gas, characterized in that: The following steps are involved: The mixed coal gas is passed into the remover solution and contacted with the cleaning foam formed by the remover solution, thereby washing and obtaining the primary washing mixed coal gas; The pre-washed mixed coal gas is subjected to heat exchange without direct contact with a refrigerant medium so that the temperature of the pre-washed mixed coal gas decreases by a temperature difference of more than 3° C., thereby obtaining a condensed mixed liquid and a re-washed mixed coal gas; The rewashed mixed coal gas is dehydrated to obtain a clean mixed coal gas.

2. The method for removing impurities from mixed coal gas according to claim 1, characterized in that: The temperature of the primary-wash mixed coal gas is 30°C-35°C, and the temperature of the secondary-wash mixed coal gas is 27°C-32°C.

3. The method for removing impurities in mixed coal gas according to claim 1, characterized in that: The heat exchange of the pre-washed mixed coal gas reduces the temperature of the pre-washed mixed coal gas by a temperature difference of 3°C-8°C.

4. The method for removing impurities in mixed coal gas according to claim 1, characterized in that: The pre-washed mixed coal gas is heat exchanged under the condition of heat insulation with the outside; The rewashed mixed coal gas is dehydrated under heat-insulated conditions from the outside.

5. The method for removing impurities from mixed coal gas according to claim 1, characterized in that: The cold medium is chilled water, and the temperature of the chilled water is 8-10°C.

6. A device for removing impurities from mixed coal gas, characterized in that: include: a first washing chamber containing a remover solution at the bottom; The first washing chamber has an air inlet pipe, a remover solution circulation pipe, a spray head and a discharge pipe; The end of the air inlet pipe is immersed in the solution area formed by the remover solution; the spray head and the discharge pipeline are both located above the solution area; the remover solution circulation pipeline is connected between the spray head and the solution area; The second washing chamber is connected to the discharge pipeline of the first washing chamber, and the second washing chamber is provided with a heat exchange mechanism; the heat exchange mechanism is provided with a refrigerant medium, which is used to condense the primary washing mixed coal gas discharged from the discharge pipeline so that the temperature difference of the primary washing mixed coal gas drops by more than 3°C, and obtain a condensed mixed liquid and a secondary washing mixed coal gas; The dehydration chamber is communicated with the second washing chamber, and the dehydration chamber has a dehydration mechanism for dehydrating the re-washed mixed coal gas.

7. The device for removing impurities from mixed coal gas according to claim 6, characterized in that: The heat exchange mechanism comprises a coil, the cold medium in the coil is chilled water, and the temperature of the chilled water is 8-10°C.

8. The device for removing impurities from mixed coal gas according to claim 6, characterized in that: The second washing chamber has a heat insulation layer; The dehydration chamber is provided with a heat insulation layer.

9. The device for removing impurities from mixed coal gas according to claim 6, characterized in that: The bottom of the second washing chamber also has a mixed liquid discharge pipeline for discharging condensed mixed liquid.

10. The device for removing impurities from mixed coal gas according to claim 9, characterized in that: It also includes a gas water seal mechanism, and the mixed liquid discharge pipeline is connected to the gas water seal mechanism.

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