Centrifugal Pump Impeller Gaps for Food Fouling
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Solution Overview
Problem
Centrifugal pumps used to convey heat-sensitive liquid food products, such as whey protein concentrates and baby food, face significant issues with product fouling when directly heated by culinary steam, leading to short service life and operational inefficiencies due to deposit formation on pump walls.
Innovation Solution
The centrifugal pump design is modified by increasing the rear and front impeller gaps and incorporating scavenging flows to flush and cool critical areas, using a portion of the liquid's volume flow to inhibit fouling and enhance cooling, which involves enlarging the impeller gaps and adding scavenging bores to direct flows to the pump housing, and integrating coolant spaces for enhanced cooling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional centrifugal pump with narrow impeller gaps is used to convey heat-sensitive liquid food products, then hydraulic efficiency is improved, but product fouling increases and service life decreases
Solution Approach 1:
The impeller is segmented into multiple blades that create separate blade channels, allowing independent control of flow paths. This segmentation enables the creation of dedicated scavenging flow paths that can be optimized for cleaning without compromising the main hydraulic flow paths, thus resolving the contradiction between hydraulic efficiency and fouling prevention
Solution Approach 2:
The scavenging bores are positioned to create preliminary flushing action at critical locations (rear impeller gap, blade channels) before product fouling can significantly develop. This preliminary cleaning action prevents deposit buildup that would otherwise reduce service life, while the main impeller geometry remains optimized for hydraulic performance
2Reliability
If the impeller gaps are increased to reduce fouling, then service life is improved, but hydraulic efficiency deteriorates
Solution Approach 1:
The impeller design applies different gap widths at different locations: larger gaps at critical fouling-prone areas (rear impeller gap, blade channel exits) and optimized smaller gaps in the main flow paths. This local differentiation allows fouling prevention where needed while maintaining hydraulic efficiency in the primary flow paths
Solution Approach 2:
The invention uses hydraulic principles by creating scavenging flows that utilize the existing liquid food product being pumped. These scavenging flows are generated through pressure differentials created by the impeller rotation and scavenging bores, using the process fluid itself for cleaning without requiring additional systems, thus maintaining overall hydraulic efficiency
3Reliability
If cooling is applied to the pump housing to prevent fouling, then service life is improved, but device complexity increases
Solution Approach 1:
The cooling function is merged with the existing pump housing structure by integrating coolant channels directly into the housing components that contact the liquid food product. This combines the cooling system with the pump housing, reducing overall device complexity while providing effective cooling at critical locations to prevent fouling
Solution Approach 2:
The liquid food product being pumped serves a dual function: it is both the process fluid being conveyed and the cooling medium for the pump housing. The product absorbs heat from the housing walls through the thin wall structure, providing self-cooling without requiring external cooling systems, thus reducing device complexity while extending service life
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 design significantly extends the service life of the centrifugal pump by reducing fouling tendencies and maintaining hydraulic delivery capacity, ensuring continuous operation without clogging, even with intermittent insults, by effectively flushing and cooling critical areas.
Implementation Method 1
A volume flow is conveyed in the impeller which is increased by the sum of all quasi-recirculating scavenging volume flows
Implementation Method 2
the housing cover (8) is provided with a coolant space (8.1) on the housing cover side through which a coolant can flow
Implementation Method 3
cooling at least the borders on the pump housing side in the area of the housing cover (8)
Data Source
Figure 1
Figure 2~4
Figure 5~6
AI summary
The invention relates to a centrifugal pump (54) for conveying heat-sensitive fluid food products (P), such as whey protein concentrates, baby food, fluid baby food concentrates, nutritious drinks or cheesemaking milk, having the further characteristics of the general terms of claim 1. The object of the invention is to create a centrifugal pump, which reduces the tendency for product fouling in the conveying of heat-sensitive fluid food products, in particular in the conveying thereof out of an infuser container for directly heating the fluid food product with water vapour, and which thereby has a significantly extended service life in relation to a hydraulically optimised centrifugal pump according to the state of the art. This is achieved in that the rear and/or front impeller gap (s1, s2) is/are increased up to many times over, in relation to a respective related minimal rear and front impeller gap (s1*, s2*) that ensures the mechanical functionality of the centrifugal pump (54), via a reduction in the width of the impeller (100) in the region of the front and the rear impeller gap (s1, s2); and in that at least the housing cover (8) is provided with a coolant chamber (8.1, 10.1) through which a coolant can flow.