What are the typical temperature and pressure levels of liquid ammonia fed into the system?
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What are the typical temperature and pressure levels of liquid ammonia fed into the system? What effects do excessively high or low temperatures have on ammonia pumps (reciprocating pumps)? What impact does it have on the system? (CO2 stripping process) This post was last edited by Durian on 2009-2-4 19:58]
Whether it is an aqueous solution or CO2 stripping, the liquid ammonia fed into the system generally has similar temperature and pressure. The temperature should be maintained between 10 and 20°C; if it is too high, vaporization occurs easily, which may even result in the liquid ammonia pump failing to operate ； Too low, resulting in a loss of cooling capacity (and ultimately a loss in electricity consumption); it’s unnecessary. The pressure should be kept between 2.0 and 2.2 MPa; if it is too high, and the ammonia is transported using pumps, this will lead to increased electricity consumption as well as higher safety risks ； Too low a value can lead to the vaporization of liquid ammonia, and may even result in an inability to measure the liquid ammonia properly.
Generally, the pressure of liquid ammonia in the inlet zone is around 2.2 MPa, with a minimum of not less than 2.0 MPa. The temperature is generally around 25 degrees, and it should not drop below 20 degrees.
A liquid will vaporize at a certain pressure and temperature; this pressure is known as the saturated vapor pressure of the liquid at that temperature, while that temperature is referred to as the saturation temperature for that pressure. The liquid ammonia will vaporize when the pressure of liquid ammonia at the inlet of the ammonia pump is lower than the saturated vapor pressure at that temperature (or in other words, when the temperature of the liquid ammonia is higher than the saturation temperature corresponding to that pressure). The vaporization of liquid ammonia causes the ammonia pump’s speed to increase sharply, resulting in a decrease in flow rate or even no flow at all. Therefore, the temperature controlled during operation is generally 10°C lower than the saturation temperature. For example, when the pressure of liquid ammonia is 2.0 MPa, its saturation temperature is around 50°C, while the actual control temperature should be below 40°C. The temperature of liquid ammonia should not change drastically, nor should it be too low; it is generally maintained above 0°C to prevent leakage caused by overcooling of the packing and the “O”-rings in the check valve gland. Therefore, the pressure and temperature of the liquid ammonia at the pump inlet must be well controlled; generally, a pressure of 2.0–2.5 MPa and a temperature of 9–40°C are appropriate
The pressure in the aqueous solution full-circulation liquid ammonia buffer tank is 1.75 MPa, while in the CO2 stripping method, where there is no medium-pressure liquid ammonia absorption tank, the pressure ranges from 2.0 to 2.2 MPa (under the condition that the ammonia removal absorption valve of the buffer tank does not leak). The liquid ammonia at the inlet of the ammonia pump vaporizes, causing the high-pressure system to overpressurize due to a low N/C ratio.
The temperature of the liquid ammonia entering the system is generally around 20 degrees Celsius, with a pressure of around 1.85 MPa; however, depending on the process used, there can be variations in the temperature and pressure of the liquid ammonia entering the system.
As mentioned above, the temperature is generally kept around 20 degrees, with the pressure ranging from 20 to 23 kilograms. However, the liquid ammonia we receive needs to have its temperature maintained constant using circulating water in a heat exchanger. Generally, the temperature of ammonia stored in tanks is around 0 degrees Celsius. Through heat exchange with circulating water, this water is then used as cooling fluid for the four large pumps (plunger type) located in the pump room, thereby ensuring normal oil pressure. This method is particularly effective in summer, achieving a two-fold benefit. Last edited by lxq700918 on 2009-2-5 23:18.]
The normal temperature range is 5 to 40°; temperatures too high will cause vaporization, resulting in the ammonia pump being unable to deliver sufficient flow, while temperatures too low will increase energy consumption. The pressure is generally a little over 2.0 MPa.
I would like to ask about the saturated vapor pressure of liquid ammonia at various temperatures