Binary Pump Flow Stability via Alternating Pressure Control
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Solution Overview
Problem
In binary pumps used in liquid chromatographs, overlapping constant pressure control sections between two liquid delivery pumps lead to impaired liquid delivery stability and accuracy, particularly due to thermal effect pulsations, which are difficult to compensate for without disrupting continuous flow.
Innovation Solution
A binary pump configuration with two independently driven liquid delivery pumps, each comprising a primary and secondary plunger pump, includes pressure sensors and an operation controller that manages suction, pre-pressurizing, and standby processes to avoid overlap of primary discharge processes, ensuring continuous flow and accurate pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If constant pressure control is performed by both liquid delivery pumps simultaneously, then pressure stability is maintained, but thermal effect pulsations occur and liquid delivery accuracy deteriorates
Solution Approach 1:
The patent implements periodic action by alternating the constant pressure control operation between the first and second liquid delivery pumps. The control unit determines which pump should perform constant pressure control based on the operational states of both pumps, ensuring that only one pump performs this function at a time. This periodic alternation prevents overlapping control sections that cause thermal effect pulsations while maintaining overall pressure stability through coordinated operation of both pumps.
2Reliability
If the standby process is extended to avoid overlap of discharge processes, then liquid delivery stability improves, but system response time increases
Solution Approach 1:
The patent applies dynamics by making the standby process duration adjustable rather than fixed. The control unit dynamically determines the standby process duration based on the specific operational states of the first and second liquid delivery pumps. When pumps are in different operational phases, the standby time is optimized to prevent overlap; when both are in similar phases, the standby time is extended to ensure stability. This dynamic adjustment balances liquid delivery stability with system response time.
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 configuration effectively avoids overlap of constant pressure control sections, enhancing the stability and accuracy of liquid delivery, thereby improving the reproducibility of mobile phase composition and reducing thermal effect pulsations.
Implementation Method 1
a primary plunger pump and a secondary plunger pump fluidly connected in series downstream of the primary plunger pump
Implementation Method 2
measuring a pressure in the pump chamber during the pre-pressurizing process and comparing the measured value with a measured value of the system pressure
Implementation Method 3
The mobile phase is at room temperature in the suction process, but has a temperature increased by being adiabatically compressed in the pre-pressurizing process
Implementation Method 4
is cooled by exchanging heat with surrounding members such as a pump head and a pipe in a subsequent discharge process
Implementation Method 5
Such a periodic temperature change of the mobile phase appears as a periodic variation of a liquid delivery flow rate through thermal expansion
Data Source
AI summary
A binary pump in which an operation controller causes each of two liquid delivery pumps to execute, while a secondary discharge process is executed, a suction process, a first pre-pressurizing process, and a standby process. The operation controller causes each of the two liquid delivery pumps to execute a second pre-pressurizing process before proceeding from the secondary discharge process to the primary discharge process. Furthermore, the operation controller causes, as long as continuous liquid delivery by each of the two liquid delivery pumps is not interrupted, at least one of the two liquid delivery pumps to execute avoidance operation of interrupting the standby process and proceeding to the second pre-pressurizing process by using the operation state of each of the two liquid delivery pumps, so as to avoid overlap of execution time zones of the primary discharge processes of the two liquid delivery pumps.