Sulfur Recovery Off-Gas Scrubbing via Pressure Gradient
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Solution Overview
Problem
The existing sulfur recovery processes incur significant operating costs due to the need for compression of sulfur-containing off-gas to high pressures, and increased capital costs from designing parts as pressure vessels to handle higher throughputs, making sulfur recovery economically inefficient.
Innovation Solution
The hydrogenated off-gas is scrubbed independently at a lower pressure using scrubbing agent from the sour gas scrubbing operation, establishing a pressure gradient to transport the off-gas without compression, and the scrubbing agent loaded with sulfur components is reintroduced into the regeneration part, allowing selective removal of sulfur components and reducing the need for elevated operating pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sulfur-containing off-gas is compressed to high pressure for reintroduction into the sour gas scrubbing apparatus, then the sulfur recovery process can maintain high operating pressure, but the operating costs increase significantly due to compression requirements
Solution Approach 1:
The process is divided into two independent scrubbing operations: the original sour gas scrubbing at high pressure and a new off-gas scrubbing at low pressure. This segmentation allows the off-gas to be treated separately without requiring compression to match the high pressure of the main scrubbing system, thereby eliminating compression energy costs while maintaining sulfur recovery effectiveness.
Solution Approach 2:
A low-pressure scrubbing column acts as an intermediary system between the sulfur recovery system and the sour gas scrubbing apparatus. This intermediary operates at low pressure to scrub the off-gas, producing a sulfur-containing scrubbing agent that is then fed to the regeneration part, avoiding the need to compress the off-gas directly into the high-pressure system.
2Productivity
If the sour gas scrubbing plant parts are designed for higher throughput at elevated pressure, then the off-gas can be reintroduced at high pressure, but the capital costs increase due to pressure vessel design requirements
Solution Approach 1:
The scrubbing system is segmented into a high-pressure sour gas scrubbing section and a low-pressure off-gas scrubbing section. The off-gas scrubbing column operates at low pressure (0.2-5 bar(a)), eliminating the need for expensive pressure vessel design and certification, thereby reducing capital costs while maintaining adequate processing throughput for the off-gas stream.
Solution Approach 2:
Instead of designing expensive pressure-resistant scrubbing equipment for the off-gas stream, the invention uses a simple low-pressure scrubbing column that can be constructed from less expensive materials and designs, significantly reducing capital investment while achieving the same sulfur removal function.
3Use of energy by moving object
If the off-gas is scrubbed independently at low pressure, then compression costs are eliminated, but additional plant parts must be provided
Solution Approach 1:
The low-pressure scrubbing column uses scrubbing agent that is circulated from the existing sour gas scrubbing system. The scrubbing agent serves multiple functions: it scrubs the off-gas in the new column and is then regenerated in the existing regeneration part. This multi-functionality approach minimizes the need for completely separate systems while achieving energy savings.
Solution Approach 2:
The off-gas scrubbing operation is merged with the existing sour gas scrubbing system by using the same scrubbing agent circulation and regeneration infrastructure. The only additional equipment needed is the low-pressure scrubbing column itself, while the pump and regeneration systems are shared, thereby reducing overall system complexity.
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 reduces operational costs by eliminating the need for gas compression and allows for more economical sulfur recovery by maintaining lower operating pressures in additional plant parts, while maintaining effective sulfur component removal and carbon dioxide disposal.
Implementation Method 1
scrubbing agent removed from the scrubbing agent circuit of the sour gas scrubbing operation is used to scrub out sulfur components
Implementation Method 2
it is possible to establish a pressure gradient between the off-gas source and the off-gas scrubbing operation which is sufficient to carry the off-gas from the sulfur recovery system to the off-gas scrubbing operation without compressing it
Implementation Method 3
Hydrogenation of the off-gas should, in this connection, be understood to mean that the sulfur dioxide comprised in the off-gas is hydrogenated to form hydrogen sulfide
Data Source
AI summary
The invention relates to a process and apparatus for recovering sulfur (9). In a sour gas scrubbing apparatus (S) comprises a scrubbing part (SP) and a regeneration part (RP), wherein sulfur components and carbon dioxide are selectively removed from a crude synthesis gas (2) with the aid of a circulating scrubbing agent (3). A sulfur-containing gas fraction (8) produced during the regeneration of loaded scrubbing agent is supplied to a sulfur recovery system (SR) in which an off-gas (10) comprising carbon dioxide and also sulfur components is formed. The off-gas is hydrogenated (H) and subsequently subjected to a gas scrubbing operation (Z). The hydrogenated off-gas (12) is scrubbed, independently of the crude synthesis gas (2), and scrubbing agent (13) removed from the scrubbing agent circuit of the sour gas scrubbing apparatus (S) is used to scrub out sulfur components from the hydrogenated off-gas (12).