Overcoming the challenge of clogged cooler in Lu’an Zhengyuan Carbon Dioxide Compression Unit 2#

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Overcoming the Problem of Clogging in the Cooler of Lu’an Zhengyuan Carbon Dioxide Compression Unit No. 2 / Author/Source: Lu’an Zhengyuan Group / Date: 2022-05-20 / Clicks: 15. Heat exchange and cooling equipment plays a crucial role in chemical production processes; poor heat exchange performance directly affects the stability of these processes, and in severe cases it can lead to overheating and overpressure, creating safety risks for production. The third-stage cooler of Unit 2 in the carbon dioxide compression section of the Baipo Zhengyuan urea plant is a jacketed cooler. Due to dirt buildup inside the jacket, the cooling water could not flow properly, which caused the temperatures in the four-in/four-out sections and the balance vessel of Unit 2 to rise significantly above normal levels, thereby having an adverse impact on production. As a result, the urea plant made up its mind to overcome this challenge. To improve equipment maintenance management, the urea production workshop makes full use of maintenance opportunities to carry out acid cleaning and high-pressure water flushing of the heat exchange equipment in order to enhance its efficiency. It also keeps a record of the degree of scaling and the cleaning status of each heat exchange unit, and formulates corrective measures promptly to address any issues identified. The three-stage cooler of Unit 2 is composed of two sets of parallel water-jacketed coolers. During the pickling process, it was found that one set had severe scaling and was blocked, so the outer layer of the jacket was cut away to remove the scale completely, followed by re-welding. Measures were also taken at the source to improve the water quality. Utilize the major maintenance to clean the circulating pool, upgrade the packing in the cooling tower, and communicate with the manufacturer to improve the chemical dosing formula for the circulating pool as well as adjust the amount of reagents used. In addition, the urea production plant is committed to innovation by installing drain pipes on the water inlet lines of each cooler, allowing for backwashing using return water at any time; all these measures contribute to improving the heat exchange efficiency to varying degrees. To fundamentally solve the problem of frequent blockages in the third-stage cooler of Unit 2. The urea production plant has made repeated improvements and conducted numerous experiments, maintaining an unwavering determination to overcome difficulties. The four-stage coolers of CO2 compression units 0#, 3#, and 4# are also jacketed coolers; however, they have never experienced as severe blockages as unit 2#. Unlike unit 2#, a straight pipe is installed at each end of each row of jackets, allowing the cooling water to flow directly into the next stage of the jacketing without passing through elbows, which **reduces the likelihood of blockages at the elbow areas. With this reference, the workshop management decided to take a bold approach and modify the cooler of Unit 2#. After four days of continuous effort, the cooler was finally modified, and it has performed well since being put into use. The temperature at the four inlet points dropped from 76.1°C to 34.5°C, the temperature at the four outlet points fell from 169°C to 130°C, and the temperature of the equilibrator decreased from 56°C to 26.5°C – all of these values are within the normal range. This not only eliminated potential safety hazards but also improved the operational efficiency of the process, effectively solving the problem of frequent clogging in the third-stage cooler of Unit 2.