1 working principle and process of ammonia synthesis Pure and proportionate hydrogen and nitrogen are chemically synthesized into ammonia. The reaction equation: N2+3H2=2NH3+ heat is reversible due to the reaction process. In order to keep the reaction in the direction of ammonia production, according to the law of chemical equilibrium transfer, it is necessary to increase the pressure of the reaction process. The higher the pressure, the more complete the reaction. . However, excessive pressure will make the equipment manufacturing and operation difficult. At present, the world's synthetic ammonia production is mainly based on the medium pressure method, that is, the synthetic pressure is in the range of 200 to 300 atmospheres. Such high pressure is the work in the process. Nitrogen-hydrogen hybrid compressors are provided. In the process of ammonia production, the flow, transportation, purification and synthesis of gas are completed under the normal operation of the compressor, and it is the heart equipment of the ammonia system. Here is a brief introduction to the most common solid ammonia-based synthetic ammonia production process. Solid raw materials mainly refer to anthracite coal, coke and carbonized briquettes. Energy Research and Utilization In the first phase of 2000, a certain size of anthracite coal or coke, in the gas generator, first alternately into the air and steam to make a semi-water gas, and then through the process of cooling, washing, dust removal, etc., into the nitrogen-hydrogen compression The machine is compressed to a certain pressure to be sent to the desulfurization section, and the hydrogen sulfide in the gas is removed, and then sent to the conversion section, so that the carbon monoxide and steam in the water gas are converted into carbon dioxide and hydrogen under the action of the coal, and then removed by the decarburization section. carbon dioxide. The decarburized gas is returned to the nitrogen-hydrogen compressor, compressed to about 13 MPa, and sent to the copper washing section to remove residual carbon monoxide and carbon dioxide from the gas. The copper-washed gas is returned to the compressor, compressed to a synthesis pressure of 32 MPa, and sent to a synthesis tower. Under the action of coal, nitrogen and hydrogen are synthesized into ammonia. Nitrogen and hydrogen, which are not synthesized as ammonia, are pressurized by means of a recycle compressor to compensate for the pressure loss caused by the synthesis process, and then enter the synthesis tower to continue the synthesis. The whole process of producing ammonia is completed by seven processes of gasification, desulfurization, compression, transformation, carbonization, copper washing and synthesis under the action of nitrogen and hydrogen compressors. 2 compressor power, efficiency and its influencing factors The compressor is a power-consuming machine. The piston reciprocates or rotates in the cylinder to reduce the volume of the gas and increase the pressure to meet the production needs. Therefore it must be powered by the drive machinery (motor) to work. When the compressor is equipped with a driver, the power level, in addition to the power required to meet the compressor duty cycle (referred to as the indicated power) In addition, the various losses of the power transfer process should also be considered. Measuring the power of the compressor and analyzing the factors affecting the power is to provide a basis for the correct selection of the driver, evaluate the performance of the compressor, and explore ways to reduce losses and improve efficiency. 2.1 Estimation of the indicated power of the compressor The indicated power of the compressor means that in the cylinder of the compressor, the work consumed in one actual cycle is called the indicated work. The indicated work consumed per unit time is called the indicated power. The compressor of the multi-stage multi-cylinder volume should be The indicated power of one cylinder volume is added, which is the indicated power of the compressor. In the actual test, in order to facilitate the calculation, the actual work of each cylinder can be simplified: the actual exhaust process pressure loss is a certain value, and the actual cycle is carried out according to the adiabatic process. 2.1.1 Compressor The exhaust volume at each level refers to the gas volume value when the gas discharged from each stage of the compressor is converted to the state of the primary suction port (pressure, temperature, humidity and compressibility coefficient) per unit time. 2.1.2 The adiabatic index of the mixed gas is related to the nature and temperature of the gas. The adiabatic index of each gas can be taken from Table 1. 2.1.3 The actual compression ratio i is the ratio of the actual exhaust pressure and the suction pressure of the compressor's i-th cylinder taking into account the pressure loss. 2.2 Measurement of Compressor Efficiency The ratio of the theoretical cycle power of the compressor (the sum of the indicated powers at all levels) to the actual power consumption is called the compressor efficiency. It is an indicator used to measure the economics of a compressor. In the specific calculation, the sum of the indicated powers of the compressors at each stage can be divided by the input power of the compressor crankshaft end. 3 measured examples Our Dandan Fertilizer Plant is a small and medium-sized fertilizer plant with an annual output of nearly 80kt of synthetic ammonia. There are 8 models of nitrogen and hydrogen compressors of the same type in the whole plant. The following uses the 4# compressor of the plant as an example to illustrate the calculation method of compressor efficiency. The test cycle lasted for 72 hours and the production was stable. Compressor model: L33DD17/320 nameplate record: first-stage air intake 17m 3 /min first-stage suction state 0.12MPa seven-stage discharge pressure 32.1MPa compressor stage 7-level matching motor model: JSQ320/12 rated power: 320kW rated Voltage: 380V rated current: 590A measured input power: 324kW measured motor actual efficiency: 93.8% 3.1 Gas composition and adiabatic index of each level Calculate the gas composition content of each level to take the hourly test average (factory timed test). The percentage of gas composition is shown in Table 2. 3.2 Compression ratio of each stage is calculated. Compressor compressors are measured at various levels. 3.3 Exhaust gas levels are measured during the test period. The production is stable. The compressors are mixed with half-water gas. According to the whole system gas balance table. The flow value is divided by the number of operating units, the amount of imported raw materials in the third-grade, and the amount of refined gas in the seven-stage imported, which are measured by the same method. 3.4 Compressor levels indicate power and efficiency
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