Ammonia Synthesis Recycle Compressor for Partial-Load Pressure Control
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Solution Overview
Problem
Existing ammonia production methods face challenges in maintaining stable pressure within the synthesis circuit due to fluctuating hydrogen and nitrogen flow rates from renewable energy sources, leading to mechanical stress and potential shutdowns of the ammonia reactor.
Innovation Solution
The method involves independently adjusting the capacity of the recycle compressor to maintain the pressure in the ammonia reactor within a predetermined range, using a PID control loop to stabilize the reactor pressure, reducing mechanical stress and avoiding shutdowns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the make-up gas flow rate is reduced due to fluctuating renewable energy supply, then the ammonia production quantity decreases, but the pressure in the synthesis circuit drops excessively causing mechanical stress and potential shutdowns
Solution Approach 1:
The invention implements a feedback control system where the actual pressure in the synthesis circuit is continuously measured and compared with a reference pressure value. Based on this comparison, the controller adjusts the recycle gas flow rate dynamically to maintain pressure within acceptable ranges, enabling continuous operation even when make-up gas flow fluctuates
Solution Approach 2:
The invention introduces dynamic adaptability by allowing the recycle compressor's operating parameters to vary continuously based on real-time pressure conditions. This dynamic adjustment of recycle gas flow rate enables the system to adapt to fluctuating make-up gas supply without requiring rigid fixed-speed operation, thus maintaining stability under varying load conditions
2Productivity
If the recycle gas flow rate is increased to maintain pressure, then the ammonia synthesis gas passes through the reactor more frequently increasing yield, but the energy consumption increases
Solution Approach 1:
The feedback control system monitors pressure and adjusts recycle gas flow rate only to the extent necessary to maintain pressure within the reference range. This prevents excessive recycling that would unnecessarily increase energy consumption while still achieving the pressure stabilization needed for maintaining ammonia yield
Solution Approach 2:
The invention changes the operating parameters of the recycle compressor dynamically based on actual process conditions. Rather than operating at fixed high flow rates, the compressor parameters are adjusted to match the minimum necessary recycle flow for pressure maintenance, optimizing the balance between ammonia yield and energy consumption
3Reliability
If the ammonia reactor is shut down to avoid mechanical stress from pressure fluctuations, then the reliability improves, but the productivity decreases and frequent startups cause additional wear
Solution Approach 1:
The feedback control system continuously monitors pressure and applies corrective actions by adjusting recycle gas flow rate before pressure fluctuations reach levels that would cause mechanical stress or require shutdown. This proactive control maintains operational stability and enables continuous production without interrupting the ammonia reactor
Solution Approach 2:
The invention applies beforehand cushioning by using the recycle gas system to counteract pressure drops before they become severe enough to cause mechanical damage or force shutdown. The recycle gas acts as a buffer that compensates for fluctuations in make-up gas supply, protecting the reactor from harmful pressure variations and enabling continuous operation
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces pressure fluctuations by up to 95%, allowing the ammonia reactor to operate efficiently even at reduced load, minimizing mechanical stress and eliminating the need for costly design modifications.
Implementation Method 1
a second compressor (recycle compressor) to compress the recycle gas
Implementation Method 2
converted in an ammonia reactor to an ammonia-containing synthesis product
Implementation Method 3
The resulting synthesis reaction, N2 + 3H2 ↔ 2NH3, is exothermic and volume-decreasing
Implementation Method 4
cooled in a series of heat exchangers to condense the ammonia and separate it in a separator
Implementation Method 5
cooled in a series of heat exchangers to condense the ammonia
Data Source
Figure 1
AI summary
The invention relates to a method and a device for the synthesis of ammonia (8), in which a gas mixture (make-up gas) (1) comprising hydrogen and nitrogen, which is supplied at a time-varying flow rate, is provided after its compression in a first compressor (make-up gas compressor) (V1) to form an ammonia synthesis gas (3), which is compressed with the aid of a second compressor (recycle compressor) (V2) and subsequently converted in an ammonia reactor (R) to an ammonia-containing synthesis product (5), from which a recycle gas (2) comprising hydrogen and nitrogen is separated in order to be recycled to form the ammonia synthesis gas (3).What is characteristic here is that a recycle compressor (V2) is used, the delivery capacity of which can be adjusted independently of the delivery capacity of the make-up gas compressor (V1) and the mass flow of the recycle gas is controlled by changing the delivery capacity of the recycle compressor (V2) so that the pressure in the ammonia reactor (R) always lies within a predetermined value range.