New Approach to Analysis of Selected Measurement and Monitoring Systems Solutions in Ship Technology

Abstract

This paper is dedicated to certain types of measurement in ship systems, analyzed based on selected case studies. In the introductory part, a simplified structure of a modern cargo ship as an object of measurement and control is presented. Next, the role of measurement in the ship's operation process is described and commented on, with focus on specifics of local and remote control, both manual and automatic. The key part of the paper is dedicated to a short overview of selected examples of measuring and monitoring systems. The basic criteria for the aforementioned selection are the vital role of the considered systems for safe and effective ship operation as well as documented innovative contribution of Gdynia Maritime University (GMU) in development of the state-of-the-art in the analysed area of measurement. Based on these criteria, the monitoring of operational parameters of main engine and temperature measurement in the ships hazardous areas have been chosen. The aforementioned measurement and monitoring systems are analysed, taking into account both innovation of technical solutions together with their ship technology environment conditions and related legal requirements. Finally, some concluding remarks are formulated.

Keywords: hazardous areas; main engine parameters; measurement; monitoring; ship environment; ship systems; temperature measurement.

Figure 1

Systems and subsystems of typical cargo ship. (Updated version based on [2]).

Figure 2

Scheme of ship to shore data transfer and online access to data with the use of web application.

Figure 3

Main engine specific fuel oil consumption (SFOC) trend with visible gradual deterioration of engine performance [14]. (Courtesy of Enamor Ltd.).

Figure 4

Combustion pressure monitoring of main engine [14]. (Courtesy of Enamor Ltd.).

Figure 5

Main engine (ME) layout with actual operation points for one-month ship operation provided by SeaPerformer system; the records below the main engine layout present momentary changes of RPM on the ME shaft in the above-defined period (Courtesy of Enamor Ltd.).

Figure 6

Photo-optical method for torque measurement, (a) concept of torque measurement, (b) relation between teeth of two rings and electrical signal for torsion angle φ = 0, (c) relation between teeth of two rings and electrical signal for torsion angle φ ≠ 0.

Figure 7

Propulsion control assistance system ETNP-10, where position of photo-optical detector is marked by ellipse, (a) two teeth rings installed on propeller shaft with photo-optical detector, (b) example of measurements, (c) actual engine load based on engine layout (Courtesy of Enamor Ltd.).

Figure 8

The temperature measurement of liquefied gas in tanks, CCR—Cargo Control Room, T_b, T_m—sensor in bottom and middle of tank to measure temperature of liquefied gas, T_u—upper sensor to measure temperature of vapors.

Figure 9

Functional diagram of temperature measurement line, where: R_s—resistance of Pt-100 sensor, R/I—transmitter-source of current 4–20 mA sink type, ZB—Zenner barrier as the associated apparatus, R_on—resistance of monitoring system, R_c—equivalent resistance of cables, U_ps—source of DC voltage, δ₁, δ₂, δ₃, δ₄ are relative errors.

Figure 10

Equivalent electrical diagram of the temperature measurement line, where: R_s—resistance of Pt-100 sensor, R/I—transmitter 4–20 mA, R_o—equivalent resistance of all resistances in the 4–20 mA current loop I, C_1,2,3,4—equivalent capacities of Pt-100 sensor and connecting cables, U_ps—source of DC voltage.

Figure 11

Small signal model of the temperature measurement line, where: G_T—conductivity of Pt-100 sensor, U/I—transmitter 4–20 mA, G_o—equivalent conductance of all resistances in the 4–20 mA current loop I_o, C_a,b,c—equivalent capacities of Pt-100 sensor and connecting cables, y_m—transadmittance of transmitter R/I.

Figure 12

Laboratory experimental circuit of temperature measurement line with the possibility of taking account capacities of the Pt-100 sensor and connecting cables, where: R/I—second-order inertial transmitter, mA—DC ammeter, U_ps—source of voltage, Ro—equivalent of all resistances in the 4–20 mA current loop, C_s1,2—equivalents of own capacities of Pt-100 sensor, C_n1,2—equivalents of own capacities of cables, K- switch.

Figure 13

Exemplary of screenshot for a transmitter with a span ΔT = T_max − T_min = 60 − (−30) = 90 °C at measured temperature T_o = 50 °C for equivalent load resistance R_o = 600 Ω.

Figure 14

Graphical illustration of influence of unexpected alternating current on a measurement error.