The landfill gas collected in the landfill site will be removed from the H2S and H2O in the landfill gas by the landfill gas pretreatment system, and then pressurized to 0.5MPa · G by the landfill gas compressor. Then, the O2 in the landfill gas will be removed by catalytic deoxidation. Then, the landfill gas will be purified to vehicle compressed natural gas by the pressure swing adsorption process, and then pressurized to 20MPa · G by the odorization and CNG compressor, and directly charged into the CNG transport tube bundle through the gas column.

3.1 预处理系统

3.1 Pretreatment system

预处理系统是垃圾填埋场填埋气利用工程中的一个重要环节，该系统不仅用于实现对填埋气的增压、稳压、温度调节、除杂质、脱水、脱硫、除臭和安全保护等处理功能，同时还是垃圾填埋场气体收集系统与提纯系统之间的燃气输送桥梁。

The pre-treatment system is an important link in the utilization engineering of landfill gas in landfills. It is not only used to achieve the functions of pressurization, pressure stabilization, temperature regulation, impurity removal, dehydration, desulfurization, deodorization, and safety protection of landfill gas, but also serves as a gas transmission bridge between the landfill gas collection system and the purification system.

垃圾填埋气（LFG）由罗茨风机抽采进入预处理系统。预处理系统设置降温除水除尘装置。系统入口设置初级过滤器以过滤LFG中的大颗粒杂志及部分液态水；设置一台换热器将原料气温度降至20℃以内，使原气体中的饱和水份以游离态析出，后经气液分离器有效去除，分离器除水率达97%以上；风机后端设置一水冷换热器用于调节预处理系统出口温度；预处理系统出口设置精密过滤器，以保证气体中固体杂志有效去除。脱硫采用干式脱硫工艺，脱硫剂采用固体氧化铁，同时为了提高脱硫剂的利用效率，本工程粗脱硫部分设计两台脱硫塔，两塔之间可以并联也可以串联操作。除臭系统采用双塔吸附，一塔再生的工艺，以保证系统能够连续运行。

Landfill gas (LFG) is extracted by Roots blower and enters the pre-treatment system. The pre-treatment system is equipped with a cooling, water removal, and dust removal device. The system inlet is equipped with a primary filter to filter large particulate matter and some liquid water in LFG; Set up a heat exchanger to reduce the temperature of the raw material to within 20 ℃, allowing the saturated water in the original gas to precipitate in a free state. After that, it is effectively removed by a gas-liquid separator, with a water removal rate of over 97% in the separator; A water-cooled heat exchanger is installed at the rear end of the fan to regulate the outlet temperature of the pre-treatment system; A precision filter is installed at the outlet of the pre-treatment system to ensure the effective removal of solid magazine in the gas. The desulfurization adopts a dry desulfurization process, and the desulfurization agent uses solid iron oxide. In order to improve the utilization efficiency of the desulfurization agent, two desulfurization towers are designed for the coarse desulfurization part of this project, which can be operated in parallel or in series. The deodorization system adopts a dual tower adsorption and one tower regeneration process to ensure continuous operation of the system.

3.2螺杆压缩

3.2 Screw compression

为了实现变压吸附提纯装置的佳分离效果，原料气必须被压缩到适合PSA工作的工艺压力。压缩机采用整体橇装式喷油螺杆压缩机，工艺气压力和流量稳定，同时出口气路设置冷却设备以调节气体温度。原料气压缩机采用喷油螺杆压缩机，设计出口压力0.6MPa，排气量2250Nm3/h，出口温度40℃。

In order to achieve optimal separation efficiency of the pressure swing adsorption purification device, the feed gas must be compressed to a process pressure suitable for PSA operation. The compressor adopts an integral skid mounted oil injection screw compressor, with stable process gas pressure and flow rate. At the same time, cooling equipment is installed in the outlet gas circuit to regulate gas temperature. The raw material gas compressor adopts an oil injection screw compressor, with a designed outlet pressure of 0.6MPa, a displacement of 2250Nm3/h, and an outlet temperature of 40 ℃.

3.3催化脱氧系统

3.3 Catalytic deoxygenation system

催化脱氧是在催化剂的作用下使填埋气中的O2和CH4、H2或者甲醇（乙醇）等气体反应脱除。本工程原料气为垃圾填埋气，在催化脱氧过程中不需要引入外源物质，直接利用气体中的甲烷进行催化燃烧，减少配套工程。

Catalytic deoxidation is the reaction between O2 and gases such as CH4, H2, or methanol (ethanol) in landfill gas under the action of a catalyst. The raw gas for this project is landfill gas. During the catalytic deoxidation process, no external substances need to be introduced, and methane in the gas is directly used for catalytic combustion, reducing the need for supporting projects.

具体脱氧工艺为：原料气经压缩、出脱硫塔后进入脱氧前余热回收系统，可实现原料气预热以达到精脱硫工作温度及脱氧催化剂起活温度，同时降低脱氧后气体温度，有效利用反应热源，降低装置能耗，同时增加装置安全性；脱氧催化剂采用设备厂家自主研发的低温高效金属催化剂，催化剂起活温度在300℃以内，同时根据反应温度配比进气量，维持催化燃烧反应在较低温度内，既能保证O2有效燃烧脱除，又能保证装置在安全稳定工况下运行；终经余热回收系统后气体温度仍较高，根据项目气候温度情况，采用风冷水及水冷双重方式保证气体温度，既能为气体降温，又能有效利用自然环境降低装置能耗。

The specific deoxidation process is as follows: the raw gas is compressed and discharged from the desulfurization tower before entering the pre deoxidation waste heat recovery system, which can achieve preheating of the raw gas to reach the working temperature of fine desulfurization and the activation temperature of the deoxidation catalyst. At the same time, the temperature of the deoxidation gas is reduced, the reaction heat source is effectively utilized, the energy consumption of the installation is reduced, and the safety of the device is increased; The deoxygenation catalyst adopts a low-temperature and high-efficiency metal catalyst independently developed by the equipment manufacturer, with the catalyst activation temperature within 300 ℃. At the same time, according to the reaction temperature ratio of the intake air, the catalytic combustion reaction is maintained at a lower temperature, which can not only ensure the effective combustion and removal of O2, but also ensure the installation operates under safe and stable working conditions; After passing through the waste heat recovery system, the gas temperature is still relatively high. Based on the climate and temperature situation of the project, a dual method of wind, cold water, and water cooling is adopted to ensure the gas temperature, which can not only cool the gas but also effectively utilize the natural environment to reduce energy consumption of the device.

3.4变压吸附提纯系统

3.4 Pressure swing adsorption purification system

变压吸附法（PSA）是在加压条件下，使CO2吸附在活性炭、分子筛、硅胶等吸附剂表明，以实现气体分离脱除CO2。其工艺原理是利用吸附剂对不同组分气体吸附力的不同，选择性吸附混合气体中的某些组分，使之与其他气体组分得以分离。

Pressure swing adsorption (PSA) is a method of adsorbing CO2 onto adsorbents such as activated carbon, molecular sieve, and silica gel under pressurized conditions to achieve gas separation and removal of CO2. The process principle is to selectively adsorb certain components of the mixed gas by utilizing the different adsorption forces of adsorbents on different gas components, so as to separate them from other gas components.

本研究设计六个吸附塔，内装专用吸附剂，可有效保证产气中甲烷纯度在90%以上，甲烷回收率大于92%。装置经过吸附、均压降压、顺放、均压升压、产品气升压过程后，吸附塔便完成了一个完整的“吸附—再生”循环，又为下一次吸附做好了准备。

This study designs six adsorption towers with dedicated adsorbents inside, which can effectively ensure that the methane purity in the gas production is above 90% and the methane recovery rate is greater than 92%. After the device undergoes the processes of adsorption, equalizing pressure reduction, clockwise release, equalizing pressure increase, and product gas increase, the adsorption tower completes a complete "adsorption regeneration" cycle, and is ready for the next adsorption.

3.5CNG压缩

3.5CNG compression

CNG压缩机组采用一体化集成式压缩机橇采用高效节能型压缩机组，四缸五级压缩，水平往复活塞式结构，机组整体橇装，水冷自动带隔音房型机组，机组采用高压填料密封、无油润滑结构设计和无平衡段设计，强制少油润滑运行。机组为四曲拐两两互成90°，使得机组平衡性较好。同时橇内还配置进气缓冲罐、回收装置（集油罐）、储气瓶组和充气柱（预留）。

The CNG compressor unit adopts an integrated compressor sled, which is an efficient and energy-saving compressor unit with four cylinders and five stages of compression, and a horizontal reciprocating plug structure. The unit is installed as a whole on a sled, with a water-cooled automatic soundproof room type unit. The unit adopts a high-pressure packing seal, oil-free lubrication structure design, and a balanced section design, and is forced to operate with less oil lubrication. The unit has four cranks arranged in pairs at a 90 ° angle to ensure good balance. At the same time, the sled is also equipped with an intake buffer tank, a recovery device (oil collection tank), an air storage bottle group, and an inflation column (reserved).

四、实际应用

4、 Practical application

丰台循环经济产业园垃圾填埋场项目每小时可产生填埋气约为4000Nm3，原采用9个火炬进行燃烧的方式来处理填埋场产生的填埋气。这样的处理方式不仅没有真正达到减少环境污染的目的，还造成严重的资源浪费。填埋气燃烧时会排放出粉尘、二氧化硫、氮氧化物等有害气体，这些气体溶于水会形成酸雨和雾霾，对当地环境造成污染。

The Fengtai Circular Economy Industrial Park Garbage Landfill Project can generate approximately 4000Nm3 of landfill gas per hour. Originally, 9 torches were used for combustion to treat the landfill gas generated by the landfill. This treatment method not only fails to truly achieve the goal of reducing environmental pollution, but also causes serious resource waste. When landfill gas is burned, harmful gases such as dust, sulfur dioxide, and nitrogen oxides are emitted. These gases dissolve in water and form acid rain and haze, causing pollution to the local environment.

为了达到资源的综合利用，北京华泰润达节能科技有限公司将丰台区循环经济产业园垃圾填埋气进行提纯制车用天然气，将收集来的垃圾填埋气经预处理（脱硫、脱水、除尘）系统、螺杆压缩、催化脱氧系统、PSA系统及CNG压缩系统等进行处理。该项目每年处理垃圾填埋气为3504万m3，可产生生物天然气1900万m3，每年可节约21024吨标煤，每年可减少CO2排放量约为70万吨。将垃圾填埋气提纯制取天然气，这样不仅能减少有害气体排放，还可以将废气资源化，产生更大的经济效益。

In order to achieve comprehensive utilization of resources, Beijing Huatai Runda Energy Conservation Technology Co., Ltd. will purify the landfill gas from the Fengtai District Circular Economy Industrial Park to produce natural gas for vehicles. The collected landfill gas will be processed through pre-treatment (desulfurization, dehydration, dust removal) systems, screw compression, catalytic deoxygenation systems, PSA systems, and CNG compression systems. This project processes 35.04 million cubic meters of landfill gas annually and can generate 19 million cubic meters of biological natural gas. It can save 21024 tons of standard coal per year and reduce CO2 emissions by approximately 700000 tons per year. Purifying landfill gas to produce natural gas can not only reduce harmful gas emissions, but also resource waste gas and generate greater economic benefits.