Improved production method of ammonia from urea
A technology of urea and urea aqueous solution, which is applied in organic chemical methods, chemical instruments and methods, preparation/separation of ammonia, etc., and can solve problems such as increased energy consumption of reactors
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example 1
[0085] In Example 1, a 40% feed solution was fed into the reactor or a 40% feed solution was generated in the reactor by feeding urea, concentrated urea and a separate stream of water or steam. (Anhydrous urea is typically granulated and coated with formaldehyde.) A heater is provided to heat the solution in the reactor. Heat input is adjusted to maintain the pressure in the reactor at a set pressure setpoint. Initially, set the pressure set point to start at a value above 30 psia. When heating the reactor to generate 30 psia gas, according to Figure 7 The data shown in set the pressure set point at a pressure corresponding to the reactor temperature. This can be achieved by various methods, such as look-up tables or by fitting Figure 7 Equation calculations for the data in . The desired solubility level, such as 30%, is initially selected for the method. This will provide a large excess of water to the urea and give the solution in the reactor a low salt evolution temp...
example 2
[0092] Example 2 is similar to Example 1 with the exception of figure 1 The temperature demand relationship in and Figure 7 and 8 Find the temperature-pressure relationship for constant water equilibrium in the reactor shown in the ammonia demand-load curve for pressure in this case. Note that using the procedures described in this patent, similar curves and relationships for other feed concentrations can be found or determined by one skilled in the art from the reactor solution concentration at various pressures and temperatures operating at a fixed feed concentration The value determines the relationship used to set the pressure set point as a function of temperature and ammonia production rate. In practice, the operating pressure set point for each fixed load can be manually adjusted and the reactor solution concentration measured. Densitometry can be used to obtain a measure of the concentration of a solution. In this example, the pressure set point is set by substitu...
example 3
[0094] Several users of the current technology use a nominal 70% urea solution obtained prior to granulation or granulation process at the time of urea manufacture. Typically 70% is diluted to 40% to 50% feed concentration. In this Example 3, 70% of the feed was fed to the reactor. Initially the reactor was filled with water such that an initial filling with a 70% solution would result in an initial solution in the reactor showing 40% urea. The product vent gas will be equivalent to a composition of 70% of the feed. In this example the reactor pressure was adjusted such that the water balance in the reactor was maintained at a concentration 40% below the feed concentration. The advantage of this method is that the heat of evaporating water is significantly reduced. In this case, heat consumption was reduced from 4526 Btu / lb ammonia produced to 2193 Btu / lb ammonia. The disadvantage is that with 40% feed solution the 30.5 Compared with the salting-out temperature of 70% fe...
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