Precipitated kraft lignin from black liquor was converted into green diesel in three steps. A mild Ni‐catalyzed transfer hydrogenation/hydrogenolysis using 2‐propanol generated a lignin residue in which the ethers, carbonyls, and olefins were reduced. An organocatalyzed esterification of the lignin residue with an in situ prepared tall oil fatty acid anhydride gave an esterified lignin residue that was soluble in light gas oil. The esterified lignin residue was coprocessed with light gas oil in a continous hydrotreater to produce a green diesel. This approach will enable the development of new techniques to process commercial lignin in existing oil refinery infrastructures to standardized transportation fuels in the future.
A new controller for throttle and spark advance to control the engine speed at idle under unknown time varying disturbances is proposed in this paper. By using measurements of the engine speed the disturbance estimator is designed to reconstruct a disturbance torque. The controller is formulated so that the throttle is used as much as possible as a main tool to produce a torque and spark advance is used to compensate intake to torque production delay. The stability of the system is proved via Lyapunov function method. [S0022-0434(00)01304-6]
By extracting lignin, pulp production can be increased without heavy investments in a new recovery boiler, the typical bottleneck of a pulp mill. The extraction is performed by using 0.20 and 0.15 weight equivalents of CO 2 and H 2 SO 4 respectively. Herein, we describe lignin esterification with fatty acids using benign reagents to generate a lignin ester mixable with gas oils. The esterification is accomplished by activating the fatty acid and lignin with acetic anhydride which can be regenerated from the acetic acid recycled in this reaction. The resulting mass balance ratio is fatty acid/lignin/acetic acid (2 : 1 : 0.1). This lignin ester can be hydroprocessed to generate hydrocarbons in gasoline, aviation, and diesel range. A 300-hour continuous production of fuel was accomplished. By recirculating reagents from both the esterification step and applying a water gas shift reaction on off-gases from the hydroprocessing, a favorable overall mass balance is realized.
A new controller for throttle and spark advance to control the engine speed at idle under unknown tame warying disturbances is proposed in this paper. By using measurements of the engine speed the disturbance estimator is designed to reconstruct a disturbance torque. The controller is formulated so that the throttle is used as much as possible as a main tool to produce a torque and spark advance is used to compensate intake to torque production delay. The stability of the system is proved via Lyapunov method.
The performance of air charge estimation algorithms in spark ignition automotive engines can be enhanced using advanced estimation techniques available in the controls literature. This paper illustrates two approaches of this kind that can improve the cylinder flow estimation for gasoline engines without external exhaust gas recirculation (EGR). The first approach is based on an input observer, while the second approach relies on an adaptive estimator. Assuming that the cylinder flow is nominally estimated via a speed-density calculation, and that the uncertainty is additive to the volumetric efficiency, the straightforward application of an input observer provides an easy to implement algorithm that corrects the nominal air flow estimate. The experimental results that we report in the paper point to a sufficiently good transient behaviour of the estimator. The signal quality may deteriorate, however, for extremely fast transients. This motivates the development of an adaptive estimator that relies mostly on the feedforward speed-density calculation during transients, while during engine operation close to steady-state conditions, it relies mostly on the adaptation. In our derivation of the adaptive estimator, the uncertainty is modelled as an unknown parameter multiplying the intake manifold temperature. We use the tracking error between the measured and modelled intake manifold pressure together with an appropriately defined prediction error estimate to develop an adaptation algorithm with improved identifiability and convergence rate. A robustness enhancement, via a s-modification with the s-factor depending on the prediction error estimate, ensures that in transients the parameter estimate converges to a pre-determined a priori value. In close to steady-state conditions, the s-modification is rendered inactive and the evolution of the parameter estimate is determined by both tracking error and prediction error estimate. Further enhancements are made by incorporating a functional dependence of the a priori value on the engine operating conditions such as the intake manifold pressure. The coefficients of this function can be learned during engine operation from the values to which the parameter estimate converges in close to steady-state conditions. This feedforward learning functionality improves transient estimation accuracy and reduces the convergence time of the parameter estimate.
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