Enterprise technological transformation

Our company is originally a small coal-based alkali producer. Indeed, improving energy efficiency is key to a company’s survival; I wonder whether the existence of an ammonia vaporization system is reasonable and feasible.

1. The water used in water ring vacuum pumps has been replaced with large-cycle water (alkaline), which is collected and supplied uniformly; this not only reduces the waste of tap water but also eliminates the problem of scaling in the pump chambers. Thousands of tons of water are used for festivals each year. (Technological upgrade in 2003) 2. The steam condensate from the entire plant is collected in one large tank; after natural cooling, it is added back to the circulating water. Thousands of tons of water are used for festivals each year. (Technological upgrade in 2006) 3. Currently, efforts are being made to utilize the heat from steam condensate for hot water circulation. (Planned for implementation in 2008) 4. The cooling capacity of the liquid nitrogen air-cooled evaporator is used to cool and recycle the vented solvent gas. (Planed for implementation in 2008) Hehe, it’s a bit far removed from coal chemical industry. . .

Generally, smaller plants with low production volumes, as well as those with high amounts of low-temperature heat, use absorption and heating regeneration along with circulating water cooling. Larger plants, on the other hand, employ centrifugal compressors for compression followed by cooling water to facilitate condensation during regeneration.

Our company replaced the piston pumps commonly used in urea production with centrifugal pumps, and the results were very good. Expanded steam is used for system insulation, and the steam jet pump is replaced by a water jet pump; this reduces both the amount of steam required and the impact of its fluctuations on evaporation, while also minimizing environmental pollution. The condensate from the system is hydrolyzed and the resulting wastewater is reused, and lithium bromide technology is employed to cool semi-water gas. :lol Last edited by yunanshu on 2008-3-2 10:59 ]

Our facility produces urea using natural gas as raw material. Recently, we have had to invest around 30 million yuan each year in technical upgrades. The plant was built in 1993, and it still functions as if it were a new installation; its operational efficiency is quite good, with the capacity to handle loads of over 110%, which is much better than what I saw at Zai Chuanhua. Back then, at Zai Chuanhua, there was an ammonia smell even 500 meters away from the entrance to the plant area. It seems that technical upgrades are indeed essential to ensure the stable operation of the equipment. A key guarantee for reducing costs.

Since the first-stage furnace previously used thick-walled conversion tubes, a small amount of nickel catalyst was required; as a result, increasing the load became a bottleneck for the entire system. Therefore, our factory switched to thin-walled conversion tubes, which allows for the use of more catalyst and improves heat transfer, thereby reducing the amount of fuel gas needed in the first-stage furnace. The renovation of the first-stage furnace cost over 40 million. Another issue is the level of carbon monoxide produced at lower levels; a 1% reduction in carbon monoxide in the raw gas results in the production of several dozen tons more ammonia, and the economic benefit from this is considerable. A higher conversion rate leads to better utilization of the feed gas, which in turn reduces hydrogen consumption during methanation as well as the amount of inert gases generated. This reduces the amount of inert gases in the ammonia synthesis process, increases the partial pressures of hydrogen and nitrogen, thereby facilitating ammonia production and reducing the volume of gas that needs to be recycled, thus saving energy spent on compression. And it reduces the amount of off-gas, thereby minimizing ammonia loss. Our factory has added two small step-down transformers, which can be connected in series or in parallel. The increase in minor low variants cost over 10 million. It’s been developing well so far. Furthermore, in summer the volume of air is insufficient, so air coolers have been added to pre-cool the air, thereby increasing the volume of air entering the compressor. I wonder which factory your brother works at?

1. Capacity expansion and upgrades to reduce marginal costs: Plants that use natural gas as a raw material are gradually undergoing capacity expansion upgrades, such as Yuntianhua, Lutianhua, and Daqing Fertilizer Plant. 2. Energy-saving upgrades to reduce energy consumption per unit of product: Efforts are first made at the process level; for example, as mentioned earlier, this involves adding small low-voltage transformers, replacing HK-40 conversion tubes with HP-50 types, and installing hydrogen separators to recover hydrogen from vent gases； Secondly, start with starting and stopping the process, such as releasing gases and recovering liquids ； Technical improvements in actual production reduce startup time ； 　　 Another aspect is the actual technical upgrades aimed at recovering the thermal energy from exhaust gases; for example, the waste heat from the flue gases in certain furnace sections can be recovered through a hierarchical utilization approach, taking into account the overall heat needs of the entire plant. In large-scale ammonia synthesis plants, the exhaust gas temperature is above 150 degrees, resulting in enormous amounts of energy being lost. The recovery of dust from urea granulation towers not only offers economic benefits but also meets environmental protection requirements. It is an energy-saving and emission-reduction project for which loans can be approved. Those with knowledge of this technology are welcome to share their views, especially those who are aware of successful modifications implemented abroad. Additionally, reducing the warming time of the synthesis tower is also a significant technical improvement.

The guy upstairs is right; for processes that produce synthetic ammonia using natural gas as a raw material, many methods have indeed been developed to recover heat from the flue gases. For example, our factory has modified the last few sets of coils, using coils with fins to increase heat retention. Although the temperature of the exhaust gases at the end of the flue is still over 150 degrees, there’s nothing that can be done about it. Since the natural gas fuel isn’t desulfurized, it’s necessary to recover heat from the flue gases above their dew point, otherwise the coils will be corroded by the sulfur present in the gases. Regarding the issue of recovering dust from the top of the urea granulation tower, the annual losses resulting from this are indeed very concerning. Below are the basic methods used for renovation by Sichuan Meifeng Chemical Industry. This post was last edited by yunanshu on 2008-3-2 11:02]

From 2003 to 2005, Sichuan Meifeng invested a total of 160 million yuan in research and development. It succeeded in developing and applying a number of internationally advanced chemical production control technologies. In the traditional natural ventilation high-tower granulation process, it adopted unique techniques such as air-cushion fluidized beds and dust atomization recovery at the top of the tower. Six invention patents were developed, including a method for granulating large particles of urea. The dust washing and recovery technology for urea granulation towers, developed independently by this company, was recognized by the China Nitrogen Fertilizer Industry Association as a key technology supporting circular economy in China.

Generally, the designed dew point temperature is 98 degrees, with a designed sulfur content of 30 PPM (organic), and a total sulfur content of 300 PPM. However, the natural gas arriving at the plant in the southwest region actually has a sulfur content of only a few dozen PPM; therefore, it is acceptable to reduce the flue gas temperature from 150 degrees to 120 degrees. The issue is that there is an excess of low-temperature heat sources, and it is only by making comprehensive use of the heat generated throughout the plant that economic benefits can be achieved through recycling. Is the dust atomization and recovery process at Meifeng carried out using water for atomization and washing? Could you introduce what process a pneumatic cushion fluidized bed is? 　　

　　Cut costs by making the most of existing resources. Creating new projects is time-consuming and labor-intensive; tapping into potential and turning waste into treasure is indeed a good approach. In fact, for large-scale chemical plants, if you examine every aspect in detail, there are really many things that can be done. Technical improvement work is a tedious yet practical task; I hope more people will get involved, discuss together, and learn from one another. 　　

Our company is an ammonia production enterprise that uses catalysts; this year, our top priorities are to set up new catalyst production lines and waste heat boilers, as well as to achieve zero wastewater discharge across the entire plant.

1. Replace vacuum extraction using urea vapor with water-based extraction. 2. Switch from electrically driven equipment to steam-driven equipment (suitable for cogeneration). 3. Frequency conversion control and chopper control can significantly reduce power consumption. 4. Decarbonized turbine pumps and copper washing differential pressure pumps offer significant energy-saving effects

1. Use a new type of steam trap to reduce steam losses, while simultaneously reusing condensate water for use as an absorbent for hydrogen chloride gas and as water for boiler deaerators. 2. By using high-efficiency, energy-saving pumps in place of traditional pumps, it seems possible to save a considerable amount of money over the course of a year. 3. Utilize waste heat for cooling or heating, complementing each other.

Enterprise technological upgrades are in line with **policies; they meet the requirements for energy conservation, environmental protection, and emission reduction, and help enhance the competitiveness of enterprises.

The synthesis of ammonia is exothermic; cooling circulating water is required to remove the heat, which is then reused after being cooled. The water temperature can reach over 90 degrees, and hot-water lithium bromide absorption chillers can be used to utilize this heat; through energy conversion, cold water at around 7 degrees can be produced for use in processes such as the cooling of semi-water gas. It can also replace energy-intensive cooling equipment such as centrifuges and cooling systems, thereby truly enabling the recovery and utilization of waste heat. You might consider the products from Yantai Ebara; they have good quality and a solid reputation.