System for preparing liquid ammonia from coke oven gas
By optimizing the coke oven gas to liquid ammonia system, adopting a combined reciprocating compressor and pure oxygen conversion, and eliminating some equipment, the problems of excessive equipment, blockage, and corrosion in the traditional system have been solved, achieving efficient and low-cost coke oven gas to liquid ammonia production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-07
- Publication Date
- 2026-04-14
AI Technical Summary
The existing coke oven gas to liquid ammonia system has a large number of compressors, resulting in a long process, high investment and operating costs, and problems such as equipment blockage, corrosion and high energy consumption.
The coke oven gas to liquid ammonia system is adopted, which includes a fiber bed dust removal unit, a gas holder unit, a screw compressor unit, a TSA pre-purification unit and a combined reciprocating compressor unit connected in series. Synthetic ammonia is produced by hydrogen extraction through PSA and external nitrogen addition. The MDEA decarbonization and methanation units are eliminated, and the centrifugal compressor is replaced by a combined reciprocating compressor. The system is converted to pure oxygen, reducing the number and scale of equipment.
It achieves a shorter process, higher single-pass conversion rate, and lower energy consumption, reducing equipment investment and operating costs, avoiding equipment corrosion and blockage problems, and improving the utilization rate of coke oven gas.
Smart Images
Figure CN224118961U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of coke oven gas to ammonia technology, specifically relating to a coke oven gas to liquid ammonia system. Background Technology
[0002] After tar removal via a fiber bed, coke oven gas enters a gas holder for buffering and pressure equalization, where the pressure is approximately 4 kPaG. A Roots blower is used to initially pressurize it to 50 kPaG. It then enters a temperature-switched adsorption (TSA) unit to remove small amounts of tar and naphthalene impurities. Next, a centrifugal compressor further pressurizes it to 2.5 MPaG before it enters a fine desulfurization unit. After removing hydrogen sulfide to 0.1 ppm, to increase the hydrogen content in the coke oven gas, methane and a small amount of heavy hydrocarbons undergo oxygen-enriched conversion, ultimately transforming them into H2 and CO2. The residual gases generated during this process are then... The remaining CO is converted into CO2 through a conversion device, and the CO2 is removed to 20ppm through the MDEA decarbonization device. To ensure that the CO+CO2 in the feed gas for ammonia synthesis is ≤5ppm, a methanation purification device is set up to remove trace amounts of CO and avoid its poisoning effect on the ammonia synthesis catalyst. The feed gas after methanation is mainly hydrogen and nitrogen. The hydrogen-nitrogen ratio is adjusted to 3:1 by introducing nitrogen into the pipeline network and sent to the synthesis gas compression unit. After being pressurized to 15MPaG by a centrifugal compressor, it enters the ammonia synthesis tower. The produced liquid ammonia is stored in a liquid ammonia storage tank.
[0003] The existing temperature-switched adsorption (TSA) unit has two stages. After the first stage removes a large amount of tar and naphthalene, it needs to be pressurized again by a centrifugal compressor to ensure more thorough removal of tar and naphthalene in the second stage under higher pressure. The atmospheric pressure TSA pretreatment process requires large equipment volume, a large amount of adsorbent, and has high system resistance, resulting in poor removal efficiency. If the first stage of the TSA unit is ineffective or malfunctions, naphthalene crystallization and blockage will occur in the compressor flow channel and cooler pipes. Tar from the coke oven gas will also adhere to the impeller, causing dynamic imbalance, reduced volumetric efficiency, and other problems, directly leading to surge and shutdown of the centrifugal compressor. The existing unit has a total of four compressors: one Roots blower and three centrifugal compressors. Centrifugal compressors are expensive, have long maintenance cycles, and affect production continuity. Furthermore, the large number of centrifugal compressors in this unit results in a large plant area, increasing civil engineering costs and making the configuration uneconomical. Existing catalytic oxidation uses oxygen-enriched conversion, resulting in a significant amount of inert gas. This leads to large-scale catalytic oxidation equipment and associated air separation units, resulting in high overall investment. Existing MDEA decarbonization units use MDEA solutions that degrade and corrode pipelines and equipment. Furthermore, the amine system experiences foaming due to contaminants and high gas velocities during operation. Existing methanation units require high-temperature operation (250-350℃), resulting in high energy consumption. Methanation catalysts are expensive, and the reaction requires strict control of impurities such as chlorine, sulfur, and phosphorus to prevent catalyst poisoning. Existing ammonia synthesis systems contain methane off-gas from the previous unit (methanation), which is an inert component, leading to large ammonia synthesis unit size and low single-pass conversion rates of effective components. Summary of the Invention
[0004] To address the aforementioned problems, the purpose of this utility model is to provide a coke oven gas to liquid ammonia system, which solves the problem of long process and high investment and operating costs caused by the large number and variety of compressors in the traditional process.
[0005] To achieve the above objectives, the technical solution adopted by this utility model includes:
[0006] A coke oven gas to liquid ammonia system includes a fiber bed dust removal unit, a gas holder unit, a screw compressor unit, a TSA pre-purification unit, and a combined reciprocating compressor unit connected in series. The combined reciprocating compressor unit includes two gas paths. The outlet of the first gas path of the combined reciprocating compressor unit is connected in series with a fine desulfurization unit, a pure oxygen conversion unit, a shift converter unit, and a PSA hydrogen extraction unit. The outlet of the PSA hydrogen extraction unit is connected to the inlet of the second gas path of the combined reciprocating compressor unit. The system also includes an external nitrogen supply pipeline connected to the inlet of the second gas path of the combined reciprocating compressor unit. The outlet of the second gas path of the combined reciprocating compressor unit is connected in series with an ammonia synthesis unit.
[0007] Preferably, the outlet of the PSA hydrogen extraction unit is also connected to another outlet of the TSA pre-purification unit.
[0008] Preferably, the screw compression unit includes two screw compressors connected in parallel.
[0009] Preferably, the outlet pressure of the screw compressor is 0.5 MPaG.
[0010] Preferably, the TSA pre-purification unit includes three sets of adsorption devices connected in series.
[0011] Preferably, the combined reciprocating compression unit is a single combined reciprocating compressor.
[0012] Preferably, the outlet pressure of the first stage gas path of the combined reciprocating compressor is 2.8 MPaG, and the outlet pressure of the second stage gas path of the combined reciprocating compressor is 15 MPaG.
[0013] Preferably, the volume ratio of hydrogen to nitrogen gas input at the second gas path inlet of the combined reciprocating compression unit is 3:1.
[0014] Preferably, the ammonia synthesis unit includes an ammonia synthesis device and an ammonia refrigeration device connected together.
[0015] Preferably, the outlet of the ammonia synthesis unit is connected in series with the liquid ammonia spherical tank unit and the loading and unloading station unit.
[0016] Compared with the prior art, the advantages of this utility model are:
[0017] (1) The coke oven gas to liquid ammonia system of this utility model, through the reasonable setting of component structure and the overall design of the system, has a shorter process, higher single-pass conversion rate and lower energy consumption under the same scale of synthetic ammonia unit, and a simplified number of compressors, resulting in lower investment and operating costs.
[0018] (2) The coke oven gas to liquid ammonia system of this utility model, through the reasonable setting of component structure, adopts PSA hydrogen extraction and external nitrogen to produce synthetic ammonia, eliminating the MDEA decarbonization device and methanation device, effectively avoiding the problems of easy degradation of MDEA solution, equipment corrosion and replacement, reducing operating costs and reducing the consumption of public works (water, electricity, gas, steam, etc.); at the same time, the high-purity hydrogen extracted by pressure swing adsorption (PSA) is mixed with external high-purity nitrogen to produce synthetic ammonia, avoiding the participation of inert gas (CH4) in the reaction, reducing the size of equipment, and improving the single-pass conversion rate of the reaction, achieving the same output of synthetic ammonia with lower compressor cycle energy consumption, shorter time, and lower equipment investment.
[0019] (3) The coke oven gas to liquid ammonia system of this utility model, through the reasonable setting of component structure, changes the traditional oxygen-enriched conversion to pure oxygen conversion, which greatly reduces the scale of the external air separation unit, while the conversion rate is high, which is conducive to strengthening production, low fuel gas consumption, high coke oven gas utilization rate, and low investment.
[0020] (4) The coke oven gas to liquid ammonia system of this utility model combines the secondary compression of coke oven gas with the compression of hydrogen and nitrogen gas by reasonably setting the component structure and adopting a combined reciprocating compressor, which eliminates the need for a centrifugal compressor and reduces equipment investment while achieving the same pressurization effect. Attached Figure Description
[0021] The accompanying drawings are provided to further illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings:
[0022] Figure 1 This is a schematic diagram of the process flow of the coke oven gas to liquid ammonia system of this utility model. Detailed Implementation
[0023] This utility model is not limited to the specific embodiments described below. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of this utility model. Unless otherwise specified, all components and devices in this utility model are based on components and devices known in the prior art.
[0024] Example
[0025] This embodiment discloses a coke oven gas to liquid ammonia system, comprising a fiber bed dust removal unit, a gas holder unit, a screw compressor unit, a TSA pre-purification unit, and a combined reciprocating compressor unit connected in series. The combined reciprocating compressor unit includes two gas paths. The outlet of the first gas path of the combined reciprocating compressor unit is connected in series with a fine desulfurization unit, a pure oxygen conversion unit, a shift converter unit, and a PSA hydrogen extraction unit. The outlet of the PSA hydrogen extraction unit is connected to the inlet of the second gas path of the combined reciprocating compressor unit. The system also includes an external nitrogen supply pipeline connected to the inlet of the second gas path of the combined reciprocating compressor unit. The outlet of the second gas path of the combined reciprocating compressor unit is connected in series with an ammonia synthesis unit.
[0026] Its function is as follows: Coke oven gas enters the fiber bed dust removal unit to remove most of the tar dust and other impurities. After entering the gas holder unit for buffering and pressure equalization, it enters the screw compressor unit for pressurization. Then, it enters the TSA pre-purification unit to adsorb and purify impurities such as benzene, naphthalene, and tar. The initial pressurization in the screw compressor unit, combined with the TSA pre-purification unit, achieves one-step removal of tar to meet the qualified index. After entering the first stage of the combined reciprocating compression unit for pressurization, it enters the fine desulfurization unit for desulfurization with additives to ensure that the total sulfur is controlled below 0.1 ppm. The resulting purified gas is CH4, which enters the pure oxygen conversion unit to decompose CH4 into H2, CO, and CO2. Then, it enters the shift unit to convert CO in the raw gas into CO2 and H2 through a shift reaction. Then, it passes through the PSA hydrogen extraction unit to obtain hydrogen with a purity of 99.99% in one step. The resulting hydrogen and nitrogen from the external nitrogen supply pipeline enter the second stage of the combined reciprocating compression unit for pressurization in a specific ratio, and then enter the ammonia synthesis unit to generate liquid ammonia.
[0027] This method utilizes PSA (Pressure Swing Adsorption) for hydrogen extraction and external nitrogen supplementation to produce synthetic ammonia, eliminating the need for MDEA decarbonization and methanation units. This effectively avoids problems such as easy degradation of MDEA solution, equipment corrosion, and replacement, reducing operating costs and utilities (water, electricity, gas, steam, etc.). Furthermore, the production of synthetic ammonia by mixing high-purity hydrogen extracted through PSA with externally supplied high-purity nitrogen avoids the participation of inert gases (CH4) in the reaction, reducing equipment size and increasing the single-pass conversion rate. For the same yield of synthetic ammonia, the compressor cycle consumes less energy, takes less time, and requires less equipment investment. Through overall system design, this application's system, with a shorter process flow, higher single-pass conversion rate, lower energy consumption, and a reduced number of compressors, results in lower investment and operating costs for a synthetic ammonia plant of the same scale.
[0028] Specifically, the outlet of the PSA hydrogen extraction unit is also connected to another outlet of the TSA pre-purification unit;
[0029] Its function is as follows: depending on the actual process, the hydrogen output from the PSA hydrogen extraction unit can also be used to backflush and desorb the impurities adsorbed by the TSA pre-purification unit. The desorbed gas is generally used for combustion in the furnace.
[0030] The fiber bed dust removal unit disclosed in this embodiment is preferably configured such that the tar + dust content at the demister outlet is <5mg / Nm³. 3 (Imported tar + dust less than 20mg / Nm) 3 Dust and mist removal devices or dust and mist removal devices with a tar + dust removal rate greater than 80% (the tar + dust at the demister inlet is higher than 20 mg / Nm³) 3 The preferred gas holder unit is a 15,000 m³ capacity unit capable of storing settling, buffering, and stabilizing gas. 3Spiral wet gas holder; the pure oxygen conversion unit is preferably a pure oxygen self-heating Φ2000, H=18000 conversion furnace with a reaction temperature of about 960℃. This application changes the traditional oxygen-enriched conversion to pure oxygen conversion, which greatly reduces the scale of the external air separation unit. At the same time, the conversion rate is high, which is conducive to strengthening production, low fuel gas consumption, high coke oven gas utilization rate, and low investment.
[0031] The fine desulfurization unit in this embodiment is preferably existing equipment, including iron-molybdenum hydrogenation catalysis, nickel-molybdenum hydrogenation catalysis, and zinc oxide adsorbent desulfurization. The iron-molybdenum hydrogenation catalyst converts most of the organic sulfur, the nickel-molybdenum hydrogenation catalyst converts the remaining organic sulfur, and zinc oxide performs the final desulfurization, ensuring that the total sulfur is controlled below 0.1 ppm. Simultaneously, a pure oxygen conversion unit is added after the fine desulfurization unit to convert methane into hydrogen, transforming impurities into effective components.
[0032] The conversion unit in this embodiment includes at least a conversion furnace and a humidifier, which converts CO in the raw gas into CO2 and H2 through a conversion reaction.
[0033] The screw compression unit disclosed in this embodiment includes two screw compressors connected in parallel. The preferred screw compressor model is one capable of reducing the naphthalene content in the tar to 1 mg / Nm³. 3 The following adsorption towers all use a screw compressor outlet pressure of 0.5 MPaG. The screw compressor is water-spray sealed, which can accept impurities such as tar and naphthalene in the raw gas. By using a screw compressor to replace the Roots blower for the initial pressurization of coke oven gas, one of the two stages of temperature-switched adsorption (TSA) in the original process can be eliminated. Instead, a single stage of temperature-switched adsorption (TSA) can be performed directly at a higher pressure (0.5 MPaG) to remove tar, naphthalene, and benzene to the qualified level in one step.
[0034] The TSA pre-purification unit disclosed in this embodiment includes three sets of adsorption devices connected in series, which are existing devices.
[0035] The combined reciprocating compression unit disclosed in this embodiment is a single combined reciprocating compressor, preferably a six-row, five-stage electrically driven compressor. The outlet pressure of the first stage gas path of the combined reciprocating compressor is 2.8 MPaG, and the outlet pressure of the second stage gas path is 15 MPaG. This application combines the secondary compression of coke oven gas with the compression of hydrogen and nitrogen gas using a combined reciprocating compressor, eliminating the need for a centrifugal compressor and reducing equipment investment while achieving the same pressurization effect.
[0036] The volume ratio of hydrogen to nitrogen gas input to the second gas path inlet of the combined reciprocating compression unit disclosed in this embodiment is 3:1.
[0037] The ammonia synthesis unit disclosed in this embodiment includes a connected ammonia synthesis device and an ammonia refrigeration unit. Both the ammonia synthesis device and the ammonia refrigeration unit are existing equipment. First, the gas enters the second gas inlet of the above-mentioned combined reciprocating compressor and is compressed to 15.0 MPaG. Then, it enters the ammonia synthesis device. Under the action of a catalyst, the hydrogen-nitrogen mixture generates ammonia (NH3). The ammonia is liquefied into liquid ammonia (NH3) by the cooling capacity of the ammonia refrigeration unit and transported to the liquid ammonia spherical tank unit for storage. Finally, it is loaded onto trucks at the loading and unloading station unit for transport of liquid ammonia.
[0038] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.
[0039] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.
[0040] Furthermore, the various implementation methods disclosed in this solution can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content invented by this disclosure.
Claims
1. A coke oven gas to liquid ammonia system, characterized in that, It includes a fiber bed dust removal unit, a gas holder unit, a screw compressor unit, a TSA pre-purification unit, and a combined reciprocating compressor unit connected in series. The combined reciprocating compression unit includes two gas paths. The outlet of the first gas path of the combined reciprocating compression unit is connected in series with the fine desulfurization unit, the pure oxygen conversion unit, the conversion unit and the PSA hydrogen extraction unit. The outlet of the PSA hydrogen extraction unit is connected to the inlet of the second gas path of the combined reciprocating compression unit. It also includes an external nitrogen supply pipeline connected to the inlet of the second gas path of the combined reciprocating compression unit. The second gas path outlet of the combined reciprocating compression unit is connected in series with the ammonia synthesis unit.
2. The coke oven gas to liquid ammonia system as described in claim 1, characterized in that, The outlet of the PSA hydrogen extraction unit is also connected to another outlet of the TSA pre-purification unit.
3. The coke oven gas to liquid ammonia system as described in claim 1 or 2, characterized in that, The screw compression unit includes two screw compressors connected in parallel.
4. The coke oven gas to liquid ammonia system as described in claim 3, characterized in that, The outlet pressure of the screw compressor is 0.5 MPaG.
5. The coke oven gas to liquid ammonia system as described in claim 1 or 2, characterized in that, The TSA pre-purification unit includes three sets of adsorption devices connected in series.
6. The coke oven gas to liquid ammonia system as described in claim 1 or 2, characterized in that, The combined reciprocating compression unit is a single combined reciprocating compressor.
7. The coke oven gas to liquid ammonia system as described in claim 6, characterized in that, The outlet pressure of the first stage gas path of the combined reciprocating compressor is 2.8 MPaG, and the outlet pressure of the second stage gas path of the combined reciprocating compressor is 15 MPaG.
8. The coke oven gas to liquid ammonia system as described in claim 1 or 2, characterized in that, The volume ratio of hydrogen to nitrogen gas input at the second gas path inlet of the combined reciprocating compression unit is 3:
1.
9. The coke oven gas to liquid ammonia system as described in claim 1 or 2, characterized in that, The ammonia synthesis unit includes a connected ammonia synthesis device and an ammonia refrigeration unit.
10. The coke oven gas to liquid ammonia system as described in claim 1 or 2, characterized in that, The outlet of the ammonia synthesis unit is connected in series with the liquid ammonia spherical tank unit and the loading and unloading station unit.